JP2006007529A - Laminated resin uniaxially stretched film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminated resin uniaxially stretched film excellent in tear strength in an MD direction and capable of controlling its surface anti-fogging properties. <P>SOLUTION: The laminated resin uniaxially stretched film has at least a resin layer (A) which is composed of 10-85 pts.wt. of an ethylene-4-12C α-olefin copolymer (i) obtained using a metallocene catalyst and with an MFR of 0.01-10 g/10 min and a density of 880-925 kg/m<SP>3</SP>, 10-85 pts.wt. of an etylene-4-12C α-olefin copolymer (ii) with an MFR of 1-100 g/10 min and a density of 926-960 kg/m<SP>3</SP>, high density polyethylene (iii) and/or 5-45 pts.wt. of at least one kind of high pressure low density polyethylene (iv) (wherein the sum total of (i), (ii), (iii) and (iv) is 100 pts.wt.) and a resin layer (B) comprising high density polyethylene with a density of 940-980 kg/m<SP>3</SP>. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a laminated resin uniaxially stretched film having excellent machine direction (MD) Elmendorf tear strength. More specifically, it is a laminated resin uniaxially stretched film having a layer made of an ethylene / α-olefin copolymer composition, which has excellent longitudinal Elmendorf tear strength and prevents exudation / bleeding of additives between layers. Relates to the film made.

A stretched film made of polyethylene or a resin composition containing polyethylene as a main component is excellent in transparency, strength characteristics, chemical resistance, and bag-making processability, and thus is used in various applications.
However, a stretched film using conventional polyethylene is low in strength in the stretching direction, so that it is easy to break the bag when the contents are put in. Therefore, the contents are damaged or the heat sealability is poor. There were insufficient points such as difficulty in processing as a bag product and poor appearance.

  In JP-A-8-134284, a polyethylene-based resin stretched film obtained by stretching a polyethylene obtained using a metallocene compound at least in a uniaxial direction has been reported, but the tear strength in the stretching direction (MD) is still noted. There is a need for improvement.

Furthermore, for example, in fruit and vegetable packaging bags, the contents may be fogged or fogged by a freezer during display, so it is necessary to prevent fogging of the film surface with an antifogging agent, but the antifogging agent contained on the inner surface is printed. The printability may be impaired due to the transition to the outer surface. Thus, there has been a demand for a film that prevents bleeding of the additive from layer to layer and has improved tear strength in the multilayer film.
JP-A-8-134284

  An object of the present invention is to provide a laminated resin uniaxially stretched film having a polyethylene resin layer, which is excellent in tearing strength in the machine direction (MD) and in which bleeding between layers of additives is prevented. And In particular, the object of the present invention is to control the antifogging property of the film surface layer such that one film surface is prevented from being fogged by moisture and the opposite surface is not antifogging.

The inventors of the present invention have reached the present invention as a result of intensive studies to solve the above problems and to obtain a stretched film having excellent longitudinal tear strength and anti-bleeding performance of additives.
That is, the present invention was completed by finding that the following laminated uniaxially stretched films have excellent tear strength and can prevent interlayer transition of additives.
(A) a resin layer comprising the following (i) (ii) and (iii) and / or (iv);
(I) a copolymer of ethylene having a melt flow rate of 0.01 to 10 g / 10 min and a density of 880 to 925 Kg / m 3 and an α-olefin having 4 to 12 carbon atoms, obtained using a metallocene catalyst; 10 to 85 parts by weight (ii) a copolymer of ethylene and an α-olefin having 4 to 12 carbon atoms having a melt flow rate of 1 to 100 g / 10 min and a density of 926 to 960 Kg / m 3; Part of at least one of the following (iii) and (iv); 5 to 45 parts by weight (iii) a high density polyethylene having a melt flow rate of 0.01 to 20 g / 10 min and a density of 940 to 970 Kg / m 3 ( iv) High pressure low density polyethylene having a density of 910 to 930 Kg / m 3 (however, the sum of (i), (ii), (iii) and (iv) is 100 parts by weight))
(B) a resin layer made of high density polyethylene having a density of 940 to 980 kg / m 3;
A laminated uniaxially stretched film having at least
The total thickness of the resin layer (A) is 25 to 95% with respect to the thickness of the entire film,
A uniaxially stretched film, wherein one of the outermost surface layers contains 0.05 to 5% by weight of an additive.

Among them, the innermost layer and the outermost layer are composed of the resin layer (A), the intermediate layer is composed of the resin layer (B), and either the innermost layer or the outermost layer includes an antifogging material. This is a preferred embodiment of the present invention.
In addition, (iii) and (iv) may be either one as long as the total amount is in the range of 5 to 45% by weight, but it is preferable that both are included.

The second aspect of the present invention is:
(A) a resin layer comprising the following (i) (ii) and (iii) and / or (iv);
(I) a copolymer of ethylene having a melt flow rate of 0.01 to 10 g / 10 min and a density of 880 to 925 Kg / m 3 and an α-olefin having 4 to 12 carbon atoms, obtained using a metallocene catalyst; 10 to 85 parts by weight (ii) a copolymer of ethylene and an α-olefin having 4 to 12 carbon atoms having a melt flow rate of 1 to 100 g / 10 min and a density of 926 to 960 Kg / m 3; Part of at least one of the following (iii) and (iv); 5 to 45 parts by weight (iii) a high density polyethylene having a melt flow rate of 0.01 to 20 g / 10 min and a density of 940 to 970 Kg / m 3 ( iv) High pressure low density polyethylene having a density of 910 to 930 Kg / m 3 (however, the sum of (i), (ii), (iii) and (iv) is 100 parts by weight))
(C) a propylene / α-olefin copolymer,
A laminated uniaxially stretched film having at least
The total thickness of the resin layer (A) is 25 to 95% with respect to the thickness of the entire film,
One of the outermost surface layers is a uniaxially stretched film characterized by containing 0.05 to 5% by weight of an additive.

The copolymer of propylene and α-olefin of the present invention is a random copolymer resin composed of propylene and an α-olefin having 2 to 12 carbon atoms other than propylene that does not lose crystallinity, or propylene and ethylene. And a ternary random copolymer resin of an α-olefin having 4 to 12 carbon atoms. The total amount of α-olefin monomers other than propylene is preferably 3% by weight or more and 10% by weight or less.
(Iii) and (iv) may be either one as long as the total amount is in the range of 5 to 45% by weight, but it is preferable that both are included.
Among them, a uniaxially stretched film in which the innermost layer and the outermost layer are made of the resin layer (A), the intermediate layer is made of the resin layer (C), and either the innermost layer or the outermost layer contains an antifogging material. This is a preferred embodiment of the present invention.

As the additive of the present invention, an antifogging material selected from the following is preferably used;
Ester / amide type nonionic surfactant mixture, alkyldiethanolamides, aliphatic alcohols, fatty acid esters.

According to the present invention, a resin laminated uniaxially stretched film having excellent longitudinal (MD) tear strength is provided, and a stretched film suitable as a packaging material is provided because of excellent impact resistance, heat sealability, and shrink pack properties. The
According to the present invention, one film surface is prevented from being fogged by moisture with an antifogging agent, and the other surface has no antifogging agent exudation, so that there is no problem in printing. Thus, there is provided a film in which oozing out is prevented and the physical properties of both surfaces are controlled.

The copolymer (i) of ethylene and α-olefin obtained using the metallocene catalyst of the present invention is obtained by copolymerizing ethylene and α-olefin having 4 to 12 carbon atoms using the metallocene catalyst. It is an ethylene / α-olefin copolymer.
Moreover, the copolymer (ii) of ethylene and α-olefin obtained using the metallocene catalyst or Ziegler-Natta catalyst of the present invention uses ethylene and carbon atoms of 4 to 12 using the metallocene catalyst or Ziegler-Natta catalyst. It is an ethylene / α-olefin copolymer obtained by copolymerizing the α-olefin.
The ethylene / α-olefin copolymer (i) and the ethylene / α-olefin copolymer (ii) may be obtained by copolymerizing the same α-olefin, and are copolymerized with different α-olefins. May be obtained.

  Examples of the α-olefin having 4 to 12 carbon atoms include butene-1, pentene-1, hexene-1, heptene-1, octene-1, nonene-1, decene-1, dodecene-1, 4-methyl. -Pentene-1,4-methyl-hexene-1, vinylcyclohexane, vinylcyclohexene, styrene, norbornene, butadiene, isoprene and the like can be mentioned, preferably hexene-1,4-methyl-pentene-1, and octene-1. . Moreover, said C4-C12 alpha olefin may be used independently and may use at least 2 type together.

  Examples of the ethylene / α-olefin copolymer (i) and the ethylene / α-olefin copolymer (ii) include an ethylene / butene-1 copolymer, an ethylene / 4-methyl-pentene-1 copolymer, An ethylene / hexene-1 copolymer, an ethylene / octene-1 copolymer, etc. are mentioned, preferably an ethylene / hexene-1 copolymer, ethylene / 4-methyl-pentene-1, and an ethylene / octene-1 copolymer. More preferred is an ethylene / hexene-1 copolymer.

The melt flow rate (MFR) of the ethylene / α-olefin copolymer (i) is 0.01 to 10 g / 10 min, preferably 0.2 to 5 g / 10 min, more preferably 0.3 to 1 g / 10 min. If the MFR of the ethylene / α-olefin copolymer (i) is less than 0.01 g / 10 minutes, the melt viscosity may become too high and the extrudability may deteriorate, and if it exceeds 10 g / 10 minutes, Mechanical strength may decrease.
The density of the ethylene / α-olefin copolymer (i) is 880 to 925 Kg / m ³ , preferably 900 to 920 Kg / m ³ , and more preferably 903 to 920 Kg / m ³ . The density of the ethylene · alpha-olefin copolymer (i) is of less than 880 kg / m ^3, if it exceeds 925 kg / m ^3, which may impact strength and tear balance is greatly reduced.

The melt flow rate (MFR) of the ethylene / α-olefin copolymer (ii) is 1 to 100 g / 10 minutes, preferably 2 to 80 g / 10 minutes, from the viewpoint of extrusion processability and mechanical strength. More preferably, it is 4-60 g / 10 minutes.
The density of the ethylene · alpha-olefin copolymer (ii), stretching from the viewpoints of impact strength and transparency are 926~960Kg / m ^3, it is desirable that preferably is 935~945Kg / m ^3.

  The melt flow rate (MFR) of the high-density polyethylene (iii) that may be used in the present invention is 0.1 to 60, preferably 0.1 to 20, more preferably from the viewpoint of extrusion processability and mechanical strength. Is 0.1 to 10, more preferably 0.5 to 5 g / 10 min, and particularly preferably 0.1 to 3 g / 10 min.

The melt flow rate (MFR) of the high-pressure method low-density polyethylene (iv) that may be used in the present invention is 0.1 to 10 g / 10 from the viewpoint of extrusion processability, mechanical strength, and transparency after retorting. It is preferably 0.1 to 8 g / 10 minutes, and more preferably 0.2 to 8 g / 10 minutes.
The density of the high-pressure low-density polyethylene (iv), from the viewpoint of maintaining the rigidity of the stretched film, 915~935Kg / m ^3, preferably 915~930Kg / m ^3, more preferably at 918~930Kg / m ³ It is desirable.

  Examples of the method for producing the ethylene / α-olefin copolymer (i) used in the present invention include known polymerization methods using a metallocene catalyst. Known polymerization methods include, for example, solution polymerization method, slurry polymerization method, high pressure ion polymerization method, gas phase polymerization method, etc., preferably gas phase polymerization method, solution polymerization method, high pressure ion polymerization method, and more preferably Is a gas phase polymerization method.

The metallocene catalyst is preferably a catalyst system including a transition metal compound having a group having a cyclopentadiene type anion skeleton. The transition metal compound having a group having a cyclopentadiene type anion skeleton is a so-called metallocene compound, for example, a general formula ML _a X _na (where M is a group 4 or lanthanide series of the periodic table of elements). L is a transition metal atom, L is a group having a cyclopentadiene-type anion skeleton or a group containing a heteroatom, and at least one is a group having a cyclopentadiene-type anion skeleton. X is a halogen atom, hydrogen or a hydrocarbon group having 1 to 20 carbon atoms, n is a valence of a transition metal atom, and a is an integer of 0 <a ≦ n. These may be used alone or in combination of at least two kinds.

  Further, the above metallocene catalysts include organoaluminum compounds such as triethylaluminum and triisobutylaluminum, alumoxane compounds such as methylalumoxane, and / or trityltetrakispentafluorophenylborate, N, N-dimethylanilinium tetrakispentafluoro. An ionic compound such as phenyl borate is used in combination.

Further, the metallocene-based catalyst described above includes the metallocene-based compound, an organoaluminum compound, an alumoxane compound, and / or an ionic compound, a particulate inorganic carrier such as SiO ₂ and Al ₂ O ₃ , polyethylene, polystyrene, and the like. It may be a catalyst supported or impregnated on a particulate organic polymer carrier.
Examples of the ethylene / α-olefin copolymer obtained by polymerization using the metallocene catalyst include ethylene / α-olefin copolymers described in JP-A-9-183816.

  Examples of the method for producing the ethylene / α-olefin copolymer (ii) used in the present invention include a known polymerization method using a known polymerization catalyst. Known polymerization catalysts include, for example, Ziegler-Natta catalysts, metallocene catalysts, and the like, preferably metallocene catalysts. As a known polymerization method, a polymerization method similar to the polymerization method used in the above-described method for producing the ethylene / α-olefin copolymer (i) can be mentioned.

  As a manufacturing method of the high density polyethylene (iii) used by this invention, the well-known polymerization method using a well-known polymerization catalyst is mentioned. Examples of the known polymerization catalyst include a Ziegler-Natta catalyst, and the known polymerization method includes polymerization similar to the polymerization method used in the above-described method for producing the ethylene / α-olefin copolymer (i). A method is mentioned.

  As a method for producing the high-pressure low-density polyethylene (iv) used in the present invention, generally, a tank reactor or a tube reactor is used, in the presence of a radical generator, a polymerization pressure of 140 to 300 MPa, a polymerization temperature of 200. Examples include a method of polymerizing ethylene under a condition of ˜300 ° C., and hydrocarbons such as hydrogen, methane and ethane are used as molecular weight regulators in order to adjust the melt flow rate.

  As a manufacturing method of the high density polyethylene (iii) used by this invention, the well-known polymerization method using well-known polymerization catalysts, such as a Ziegler-Natta catalyst, is mentioned. As a well-known polymerization method, the polymerization method similar to the polymerization method used with the manufacturing method of the above-mentioned ethylene-alpha-olefin copolymer (i) is mentioned.

The laminated resin uniaxially stretched film of the present invention comprises an ethylene / α-olefin copolymer (i), an ethylene / α-olefin copolymer (ii), and high-density polyethylene (iii) or high-pressure low-density polyethylene (iv). ) Is a laminated resin uniaxially stretched film having a resin layer (A) containing at least one of the above and a high-density polyethylene layer (B).
In the present invention, a propylene / α-olefin copolymer (C) layer may be used instead of the high-density polyethylene layer (B).
The proportion of each polymer in the resin layer (A) is as follows:
(I) The ethylene / α-olefin copolymer is 10 to 85 parts by weight, preferably 20 to 70 parts by weight, and more preferably 20 to 65 parts by weight.
(Ii) The ethylene / α-olefin copolymer is 10 to 85 parts by weight, preferably 15 to 60 parts by weight, and more preferably 20 to 60 parts by weight.
(Iii) and (iv) are 5-45 parts by weight in total, preferably 15-40 parts by weight. If the total amount is within the above range, it is not particularly limited individually.
(Iii) High density polyethylene is preferably 2 to 20 parts by weight, more preferably 5 to 17 parts by weight,
(Iv) The high-pressure low-density polyethylene is preferably 3 to 25 parts by weight, more preferably 10 to 23 parts by weight.

  The preferred melt flow rate (MFR) of the resin composition (A) of the present invention is 0.1 to 10 g / 10 min, preferably 0.2 to 4 g / 10 min, more preferably 0.3 to 3 g / 10 min. If the melt flow rate (MFR) is within this range, in the film formation by the inflation method, the extrudability of the resin is good and the bubbles are stable. Therefore, the film formation by the inflation method is used when producing the original film before the stretching process. Therefore, a more preferable resin composition is obtained.

The density of the resin composition (A) of the present invention is recommended to be 898 to 960 Kg / m ³ , preferably 900 to 950 Kg / m ³ , and more preferably 900 to 940 Kg / m ³ .

  Other production methods of the resin composition (A) in the present invention include, for example, ethylene / α-olefin copolymer (i), ethylene / α-olefin copolymer (ii), high-density polyethylene (iii) and Examples thereof include a method of dry blending or melt blending the high-density low-density polyethylene (iv). Various blenders such as Henschel mixer and tumbler mixer can be used for dry blending, and various mixers such as single-screw extruder, twin-screw extruder, Banbury mixer, and hot roll can be used for melt blending. it can.

  Moreover, as a manufacturing method of the resin composition (A) of this invention, the following desirable manufacturing methods are mentioned, for example.

1.1 After polymerization of ethylene / α-olefin copolymer (i), (ii) and high density polyethylene (iii) continuously using two polymerizers and divided into two or more reaction conditions, High pressure method A method of mixing low density polyethylene (iv).
2. A method in which each component is polymerized in a plurality of polymerization vessels by a multistage polymerization process to finally obtain the polyethylene-based resin composition of the present invention.
3. A method in which any two components of each component are produced by multistage polymerization, and then the remaining two components are mixed.

  In the present invention, high-density polyethylene (iii) is preferably high-density polyethylene having a plurality of DSC melting peaks. The phrase “having a plurality of DSC melting peaks” includes not only the case where two or more peaks are clearly seen in the DSC chart, but also the case where one peak is associated with a shoulder.

  As a resin layer other than the resin layer (A) constituting the resin laminated uniaxially stretched film of the present invention, at least one of them is a layer made of high-density polyethylene (B) or a propylene / α-olefin copolymer (C). is there.

(Method for producing high-density polyethylene (B))
The high-density polyethylene (B) used in the present invention can be obtained by the following production method.
As a method for producing the high-density polyethylene used in the present invention, a known polymerization catalyst and a polymerization method can be used. Examples of the known polymerization catalyst include a Ziegler-Natta catalyst, and the like. Examples thereof include a slurry polymerization method using a Ziegler-Natta catalyst.

(Producing method of propylene / α-olefin copolymer (C))
The propylene / α-olefin copolymer used in the (C) layer of the present invention can be obtained by the following production method. A copolymer of propylene and an α-olefin is a random copolymer resin composed of propylene and an α-olefin having 2 to 12 carbon atoms other than propylene that does not lose crystallinity, propylene, ethylene, and the number of carbon atoms. It is a ternary random copolymer resin with 4 to 12 α-olefin.
Examples of the α-olefin include ethylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene and the like. Preferably, ethylene and 1-butene are used. As the content of repeating units derived from monomers other than propylene, the total amount of monomers other than propylene is preferably 3% by weight or more and 10% by weight or less. If it is less than 3% by weight, the interlayer adhesive strength is lowered, which is not preferable. The content of the repeating unit derived from a monomer other than propylene is more preferably 3% by weight or more and 6% by weight or less.

  The melt flow rate (MFR) of the copolymer of propylene and α-olefin is preferably 1.0 to 10.0 g / 10 min. A method for producing a copolymer of propylene and an α-olefin is not particularly limited, and examples thereof include a gas phase polymerization method and a solvent polymerization method, and a gas phase polymerization method is particularly preferable. As the catalyst used for the polymerization, various known catalysts can be used. Preferably, the catalyst is obtained by using a multisite catalyst obtained by using a solid catalyst component containing a titanium atom, a magnesium atom and a halogen atom, or a metallocene complex. Single site catalyst.

In the resin laminated uniaxially stretched film of the present invention, the thickness of the resin layer (A) is 25 to 95% of the thickness of the entire film. More preferably, it is 30-90%, More preferably, it is 40-90%. If the thickness of (A) is less than 25% of the total, sufficient tear strength may not be obtained. In addition, when there are two or more resin composition layers (A), the total thickness should just be in the said range.
In the resin laminated uniaxially stretched film of the present invention, a uniaxially stretched film in which the thickness of the resin layer (B) or the resin layer (C) is 5 to 75% of the total thickness of the film is preferable. More preferably, it is 10-70%, More preferably, it is 10-60%.

If the thickness of (B) or (C) exceeds the above range, sufficient tear strength may not be obtained. Moreover, when the thickness of (B) or (C) is less than the said range, transfer of an additive may not be prevented.
The high-density polyethylene layer (B) or the propylene / α-olefin copolymer layer (C) has an effect of preventing diffusion of the additive in the thickness direction. Therefore, the (B) to (C) layers do not contain an additive, and when there are a plurality of (B) to (C) layers, at least one of the (B) to (C) layers does not contain an additive, is required.

As long as the resin laminated uniaxially stretched film of the present invention has a resin layer (A) and a high-density polyethylene resin layer (B), the number of laminated layers is not particularly limited, and has a layer made of another resin composition. May be.
When the number of layers is 2, it is inevitably only the resin layer (A) and the resin layer (B), and the resin layer (A) contains an additive. When the number of layers is 3 or more, a plurality of layers composed of the resin layer (A) and / or the resin layer (B) may be present, or layers other than (A) and (B) may be included. The surface layer containing the additive may be the resin layer (A) or another layer. As layer structure,
(A) layer [additive containing] / (B) layer [no additive] / (A) layer [no additive]
(A) layer [containing additive] / (B) layer [without additive] / other resin layer [without additive]
Other resin layer [containing additive] / (B) layer [without additive] / (A) layer [without additive]
(B) layer [additive containing] / (A) layer [no additive] / (B) layer [no additive] / (A) layer [no additive]
Etc. can be illustrated.

The layer structure of the resin laminated uniaxially stretched film of the present invention is not limited to these, and the type of resin and the structure of the layer can be appropriately selected according to the purpose.
The propylene / α-olefin copolymer layer (C) may have the same layer structure as the high-density polyethylene resin layer (B).

  Examples of the method for obtaining the resin laminated uniaxially stretched film of the present invention include a method of uniaxially stretching a laminated film having at least one resin layer (A). Examples of the method for producing the laminated film include known methods such as a co-extrusion method and an extrusion coating method (also referred to as an extrusion lamination method). For example, it can be obtained by coextrusion of the resin composition constituting the resin layer (A) of the present invention and the resin as another layer.

  Further, extrusion lamination is performed on a film made of a resin composition constituting the resin layer (A) obtained by a known film forming method such as an inflation film forming method, a T-die cast film forming method, a calendar forming method, or a press forming method. Alternatively, another resin can be laminated by a method such as dry lamination.

The resin laminated uniaxially stretched film of the present invention can be obtained by uniaxially stretching the obtained laminated film. As a stretching method, for example, a conventionally known method such as a method of stretching in the MD (longitudinal direction) through a heated roll and a roll rotating at a different speed from the roll can be applied.
The draw ratio is preferably 3 to 15 times, more preferably 4 to 10 times.

  The present invention provides a uniaxially stretched film having a machine direction (MD) Elmendorf tear strength that is remarkably improved by the presence of the resin layer (A) as at least one layer of a resin laminate.

  Other polymers, antioxidants, lubricants, antistatic agents, processability improvers, antiblocking agents, and the like may be added to each layer of the resin laminated uniaxially stretched film of the present invention as necessary. Other resins and additives may be used alone or in combination of at least two kinds.

  Other polymers may be added to the resin layer (A) as long as the object of the present invention is not impaired. Examples of the other polymers include polyolefin resins, which are added to improve rigidity and heat resistance. And a polypropylene-based thermoplastic elastomer added to improve impact strength. These other polymers may be added in a proportion of usually 1 to 30 parts by weight based on 100 parts by weight of the total of copolymer (A) and copolymer (ii).

  Examples of the antioxidant include 2,6-di-t-butyl-p-cresol (BHT), tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane. (Trade name: IRGANOX 1010, manufactured by Ciba Specialty Chemicals), n-octadecyl-3- (4′-hydroxy-3,5′-di-t-butylphenyl) propionate (trade names: IRGANOX 1076, Ciba Specialty) Chemicals) phenolic antioxidants, bis (2,4-di-t-butylphenyl) pentaerythritol diphosphite, tris (2,4-di-t-butylphenyl) phosphite, 2,4 , 8,10-Tetra-t-butyl-6- [3- (3-methyl-4-hydroxy-5-t-butylphenyl) And phosphite-based antioxidants such as propoxy] dibenzo [d, f] [1,3,2] dioxaphosphepine (trade name: Sumilizer GP, manufactured by Sumitomo Chemical Co., Ltd.).

  Examples of the lubricant include higher fatty acid amides and higher fatty acid esters. Examples of the antistatic agent include glycerin esters, sorbitan acid esters and polyethylene glycol esters of fatty acids having 8 to 22 carbon atoms. Examples of the processability improver include fatty acid metal salts such as calcium stearate, fluorine resins, and the like, and examples of the antiblocking agent include inorganic antiblocking agents and organic antiblocking agents, and inorganic blocking prevention. Examples of the agent include silica, calcium carbonate, and talc. Examples of the organic antiblocking agent include cross-linked polymethyl methacrylate, cross-linked poly (methyl methacrylate-styrene) copolymer, cross-linked silicone, and cross-linked. Examples thereof include polystyrene powder.

  Examples of the mixing method of other resins and additives added as necessary include, for example, resins and additives together with the resin composition of the present invention or other resins, a single screw extruder, a twin screw extruder, a Banbury. The method of melt-kneading using various mixers such as a mixer and a heat roll and then subjecting to film processing, the polyethylene resin composition of the present invention and other resins and additives are dried using various blenders such as a Henschel mixer and a tumbler mixer. After blending, a method of subjecting to film processing, or after dry blending with the polyethylene-based resin composition of the present invention using various blenders such as a Henschel mixer and a tumbler mixer with at least one masterbatch of other resins and additives. Examples include a method for film processing.

In the present invention, the following additives can be used;
[Antioxidant]
Examples of the stabilizer include 2,6-di-t-butyl-p-cresol (BHT), tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane ( Product name: IRGANOX 1010, manufactured by Ciba-Geigy Corporation), n-octadecyl-3- (4′-hydroxy-3,5′-di-t-butylphenyl) propionate (trade name: IRGANOX 1076, manufactured by Ciba-Geigy Corporation), etc. And phosphite stabilizers such as bis (2,4-di-t-butylphenyl) pentaerythritol diphosphite and tris (2,4-di-butylphenyl) phosphite.

[Antistatic agent]
Examples of the antistatic agent include alkyl diethanolamides, aliphatic alcohols, fatty acid esters and the like. Examples of fatty acid esters include glycerin fatty esters, such as diglycerin monostearate (DGMS), glycerin monostearate (GMS), glycerin monoheptadecylate, glycerin monopalmitate, glycerin monoester. Examples include myristylate, glycerol monolaurate, glycerol monocaprate, glycerol monopelargonate, etc., and glycerol difatty acid esters, glycerol difatty acid esters, and the like. Preferable are polyglycerol fatty acid monoesters such as diglycerol monostearate. For example, examples of alkyl diethanolamides include stearyl diethanolamide, laurin diethanolamide, and oleyl diethanolamide. Examples of aliphatic alcohols include stearyl alcohol.

[Ultraviolet absorber]
Examples of the weathering stabilizer include benzophenone series, benzotriazole series, benzoate series, cyanoacrylate series, organonickel compounds, HALS (Hindered Amine Light Stabilizer) and the like.
[Lubricant]
Examples of the lubricant include higher fatty acid amides and higher fatty acid esters.
[Processability improver]
Examples of the processability improver include fatty acid metal salts such as calcium stearate, fluorine resins, and the like.

As the additive of the present invention, an antifogging agent is preferably used. One anti-fogging agent is contained on the surface of one of the resin laminated uniaxially stretched films. A resin laminated uniaxially stretched film can be obtained.
Examples of the antifogging agent component of the present invention include an ester / amide type nonionic surfactant mixture (manufactured by Takemoto Yushi Co., Ltd .: MCS-622), but are not particularly limited. Examples of compounds that can be used include:
Examples of the surfactant component include alkyl diethanolamides, aliphatic alcohols, fatty acid esters and the like. Examples of fatty acid esters include glycerin fatty esters, such as diglycerin monostearate (DGMS), glycerin monostearate (GMS), glycerin monoheptadecylate, glycerin monopalmitate, glycerin monoester. Examples include myristylate, glycerol monolaurate, glycerol monocaprate, glycerol monopelargonate, and glycerol difatty acid esters and glycerol trifatty acid esters corresponding to these glycerol monofatty acid esters. Examples of alkyl diethanolamides include stearyl diethanolamide, laurin diethanolamide, and oleyl diethanolamide. Examples of aliphatic alcohols include stearyl alcohol.

  The resin laminate is a resin laminate uniaxially stretched film comprising an outermost layer, an innermost layer and an intermediate layer, and the resin laminate uniaxially stretched film having the resin layer (A) in which at least the innermost layer is blended with an antifogging agent is The preferred embodiment of the laminated stretched film having antifogging properties of the present invention.

Although the preferable specific example of the resin laminated | multilayer uniaxially stretched film which has the anti-fogging property of this invention is shown below, this invention is not limited to these.
Example 1
Outermost layer: Resin layer (A)
Intermediate layer: high density polyethylene or propylene / α-olefin copolymer Innermost layer: resin layer (A)
Example 2
Outermost layer: high density polyethylene or propylene / α-olefin copolymer Intermediate layer: resin layer (A)
Innermost layer: Resin layer (A)
In the above example, by adding an additive and a slip agent to the innermost resin layer (A), a resin laminated uniaxially stretched film having excellent tear strength in MD (longitudinal direction) and having antifogging properties Obtainable. Further, in these examples, it is possible to prevent the additive from moving to the outer surface (bleed) and to exhibit an excellent effect that only the innermost layer can exhibit antifogging properties.

  Such a resin laminated uniaxially stretched film having excellent tear strength in MD (longitudinal direction) and having antifogging properties can be suitably used as an antifogging film for applications such as a freshness-holding film.

EXAMPLES Next, although this invention is demonstrated in detail based on an Example and a comparative example, this invention is not limited at all by these Examples.
A three-layered resin laminated film was manufactured by an inflation film forming method.
The basic physical properties and film physical properties of the resin compositions used in Examples and Comparative Examples were measured according to the following methods.

[Basic physical properties of resin composition]
(1) Density (Unit: Kg / m ³ )
For the density, the strand obtained at the time of measuring the melt flow rate (MFR) at 190 ° C. under a load of 2.16 kg was treated at 120 ° C. for 2 hours, gradually cooled to room temperature over 1 hour, and then used with a density gradient tube. It was measured.
(2) Melt flow rate (MFR, unit: g / 10 minutes)
According to ASTM D1238-65T, measurement was performed under conditions of 190 ° C. and 2.16 kg load.
(3) Gross (Unit:%)
The measurement was performed according to the method defined in ASTM D1922.
(4) Elmendorf Tear Strength Elmendorf Tear Strength was measured using an Elmendorf Tear Tester manufactured by Toyo Seiki Seisakusho in accordance with ASTM D1922.
The case where the cut is put in the film take-off direction is MD (vertical direction), and the case where the cut is put at right angles to the take-off direction is TD (lateral direction).
(5) Tensile initial elastic modulus A dumbbell having a size corresponding to JIS K6718 is used as a punched test piece, and MD (longitudinal direction) is used when punching in parallel with the film drawing direction, and TD is used when punching perpendicular to the film drawing direction. (Lateral direction).
A test piece is set in an air chuck of an Instron type universal material testing machine, a tensile test is performed at a distance between chucks of 86 mm and a tensile speed of 200 mm / min, and an inclination with respect to a displacement of initial stress is defined as an initial tensile elastic modulus.

  The ethylene / α-olefin copolymer (i), ethylene / α-olefin copolymer (ii), high-density polyethylene (iii), and high-pressure method low-density polyethylene (iv) used in Examples and Comparative Examples are as follows. Indicated.

(I) Ethylene / α-olefin copolymer Ethylene-hexene-1 copolymer: MFR = 0.5 g / 10 min, density = 902 Kg / m ³
(Ii) Ethylene / α-olefin copolymer Ethylene-hexene-1 copolymer: MFR = 5 g / 10 min, density = 940 Kg / m ³
The ethylene / α-olefin copolymer (i) and the ethylene / α-olefin copolymer (ii) were produced by a gas phase polymerization method using a known metallocene catalyst.
(Iii) High density polyethylene HDPE: MFR = 0.11 g / 10 min, density = 950 Kg / m ³
It was produced by a slurry polymerization method using a Ziegler-Natta catalyst.
(Iv) High pressure method low density polyethylene LDPE (iv): MFR = 0.6 g / 10 min, density = 923 Kg / m ³
The high-pressure low-density polyethylene was produced by a radical polymerization method using a tubular reactor.

[Production of resin composition]
A dry blend of ethylene / α-olefin copolymer (i), ethylene / α-olefin copolymer (ii), high density polyethylene (iii) and high pressure low density polyethylene (iv) with the composition shown in Table 1 Subsequently, resin composition pellets were produced at a processing temperature of 190 ° C. and an extrusion rate of 50 kg / hr using a 46 mmφ twin-screw extruder manufactured by Ikekai Tekko Co., Ltd.
A resin layer (A) was formed using this resin composition.

(B) High-density polyethylene High-density polyethylene used was a slurry produced by a slurry polymerization process using a Ziegler-Natta catalyst.
Density = 950kg / m3, MFR = 1.1g / 10min

MCS-622 (manufactured by Takemoto Yushi Co., Ltd.) was used as the antifogging agent.
95% by weight and 5% by weight of the resin composition (A) were mixed with a biaxial kneader to prepare an antifogging agent master batch. This antifogging agent MB was added to the innermost layer by dry blending a predetermined amount (adjusted so that 15000 ppm was added as an antifogging agent) to the resin used for the innermost layer.

[Manufacture of resin laminated uniaxially stretched film]
Table 1 shows the structures of the multilayer films of Examples and Comparative Examples. In the table, PO represents the resin composition (A), and HDPE represents the high-density polyethylene (B). The manufacturing method of the multilayer film is as follows.
[Adjustment of stretch fabric]
Using a three-layer inflation molding machine with a lip opening of 3.5 mm (manufactured by Alpine Co., Ltd .: three 50 mmφ extruders), a 200 μm-thick original fabric is adjusted at a blow ratio of 2 and an extrusion rate of about 100 kg / hr. Each film was formed under the following conditions.

Comparative Example 1: Extrusion amount (resin temperature)
Outermost layer / intermediate layer / innermost layer = 33 [kg / h] (200 ℃) / 33 [kg / h] (200 ℃) / 33 [kg / h] (200 ℃)
Comparative Example 2: Extrusion amount (resin temperature)
Outermost layer / intermediate layer / innermost layer = 40 [kg / h] (200 ° C) / 40 [kg / h] (200 ° C) / 20 [kg / h] (200 ° C)
Comparative Example 3: Extrusion amount (resin temperature)
Outermost layer / intermediate layer / innermost layer = 33 [kg / h] (200 ℃) / 34 [kg / h] (200 ℃) / 33 [kg / h] (200 ℃)
Comparative Example 4: Extrusion amount (resin temperature)
Outermost layer / intermediate layer / innermost layer = 45 [kg / h] (200 ° C) / 10 [kg / h] (200 ° C) / 45 [kg / h] (200 ° C)
Example 1: Extrusion amount (resin temperature)
Outermost layer / intermediate layer / innermost layer = 45 [kg / h] (200 ° C) / 10 [kg / h] (200 ° C) / 45 [kg / h] (200 ° C)
Example 2: Amount of extrusion (resin temperature)
Outermost layer / intermediate layer / innermost layer = 25 [kg / h] (200 ℃) / 50 [kg / h] (200 ℃) / 25 [kg / h] (200 ℃)

[Production conditions for stretched film]
MD (longitudinal) is passed between the heated roll and a roll rotating at a speed different from the heated roll at the drawing temperature where the surface temperature (stretching temperature) is shown in the table of experimental examples. The film was stretched in the direction and the stretch ratio shown in Table 1 was carried out to obtain a stretched film. In addition, the obtained film is subjected to a 50 dyn corona treatment after the stretching step, and subjected to an aging treatment for 1 day in a thermostatic chamber at 30 ° C., and then the film physical properties are evaluated.

[Anti-fogging performance evaluation]
Cover the sample film in a beaker containing 20 ° C water and leave it in an atmosphere at 5 ° C for 1 hour.
Three-level evaluation (1: There is water droplets and is opaque 2: There are water droplets, but the inside can be confirmed softly 3: There are water droplets but is transparent)

Comparative Example 1: The anti-fogging property cannot be expressed and the Elmendorf tear strength is weak, which is not practical.
Comparative Example 2: Although the antifogging surface can be controlled, the Elmendorf tear strength is weak and impractical.
Comparative Example 3: Although the Elmendorf tear strength is high, the antifogging surface cannot be controlled, and when a printing layer or the like is provided on the outer surface, printability is hindered.
Comparative Example 4: Although the antifogging surface can be controlled, the Elmendorf tear strength is weak and impractical.
Example 1: The antifogging surface can be controlled, and the Elmendorf tear strength is strong and practical.
Example 2: The antifogging surface can be controlled, and the Elmendorf tear strength is strong and practical.

The present invention provides a uniaxially stretched film that has excellent tear strength in the MD direction and can control the transfer of additives between layers.
The resin-laminated uniaxially stretched film of the present invention provides a packaging material that is excellent in impact resistance, heat sealability, and shrink pack properties, and has excellent freshness retention, appearance, and cold resistance.
In addition, although the resin laminated uniaxially stretched film of the present invention has one surface having antifogging properties, the other surface has no bleeding of the antifogging agent, so that printability is not impaired and display of contents is not impaired.

Claims (4)

(A) a resin layer comprising the following (i) (ii) and (iii) and / or (iv);
(B) a resin layer made of high density polyethylene having a density of 940 to 980 kg / m ³ ;
A laminated uniaxially stretched film having at least
The total thickness of the resin layer (A) is 25 to 95% with respect to the thickness of the entire film,
There is at least one layer comprising the resin layer (B) and containing no additive,
One of the outermost layers contains 0.05 to 5 wt% additive,
A uniaxially stretched film characterized by that.
(I) A copolymer of ethylene having a melt flow rate of 0.01 to 10 g / 10 min and a density of 880 to 925 Kg / m ³ and an α-olefin having 4 to 12 carbon atoms, obtained using a metallocene catalyst 10 to 85 parts by weight (ii) a copolymer of ethylene and an α-olefin having 4 to 12 carbon atoms having a melt flow rate of 1 to 100 g / 10 min and a density of 926 to 960 Kg / m ³ ; 85 parts by weight At least one of the following (iii) and (iv); 5-45 parts by weight (iii) A melt flow rate of 0.01 to 20 g / 10 minutes and a density of 940 to 970 Kg / m ³ Density polyethylene (iv) High-pressure low-density polyethylene having a density of 910 to 930 Kg / m ³ (however, the sum of (i), (ii), (iii) and (iv) is 100 parts by weight). (A) a resin layer comprising the following (i) (ii) and (iii) and / or (iv);
(C) a resin layer comprising a propylene / α-olefin copolymer,
A laminated uniaxially stretched film having at least
The total thickness of the resin layer (A) is 25 to 95% with respect to the thickness of the entire film,
There is at least one layer comprising the resin layer (C) and containing no additive,
One of the outermost layers contains 0.05 to 5 wt% additive,
A uniaxially stretched film characterized by that.
(I) A copolymer of ethylene having a melt flow rate of 0.01 to 10 g / 10 min and a density of 880 to 925 Kg / m ³ and an α-olefin having 4 to 12 carbon atoms, obtained using a metallocene catalyst 10 to 85 parts by weight (ii) a copolymer of ethylene and an α-olefin having 4 to 12 carbon atoms having a melt flow rate of 1 to 100 g / 10 min and a density of 926 to 960 Kg / m ³ ; 85 parts by weight At least one of the following (iii) and (iv); 5-45 parts by weight (iii) A melt flow rate of 0.01 to 20 g / 10 minutes and a density of 940 to 970 Kg / m ³ Density polyethylene (iv) High-pressure low-density polyethylene having a density of 910 to 930 Kg / m ³ (however, the sum of (i), (ii), (iii) and (iv) is 100 parts by weight). The innermost layer and the outermost layer are made of a resin layer (A), the intermediate layer is made of a resin layer (B), and either the innermost layer or the outermost layer contains an additive. Axial stretched film. A packaging material comprising the resin laminated uniaxially stretched film according to any one of claims 1 to 3.