KR102151932B1 - Polyethylene-based resin composition and polyethylene-based film - Google Patents

Abstract

(Problem) According to the present invention, a polyethylene-based resin composition and a polyethylene-based film can be obtained that ensure sufficient transparency even under a heating environment for a long time and are resistant to friction.
(Solution means) Having a density of 0.920 to 0.950 g/cm 3, both the dynamic friction coefficient D and the static friction coefficient S are 0.30 or less, and the ratio D/S of the dynamic friction coefficient D to the static friction coefficient S is 1.0 or less. A polyethylene-based resin composition, characterized in that.

Description

Polyethylene resin composition, polyethylene-based film TECHNICAL FIELD [POLYETHYLENE-BASED RESIN COMPOSITION AND POLYETHYLENE-BASED FILM}

The present invention relates to a polyethylene-based resin composition and a polyethylene-based film exhibiting a low coefficient of friction.

Currently, polyethylene films are used in applications such as packaging substrates, agricultural films, and wire covering materials. The use of a polyethylene film exhibiting high strength extends to a wide variety of fields, and improvement and development of the film strength properties are still in progress at present.

In particular, in the agricultural film used for a long period of time, depending on the season or environment, operations such as winding up the film occur, and at that time, frictional breakage between the metal part of the hoisting machine and the film, or between films occurs. In particular, there is a high demand for a film that is resistant to breakage while maintaining the transparency of the plastic house required for collecting solar radiation.

As a means for preventing frictional breakage, it is effective to reduce the coefficient of friction of the film surface. As a film having a low coefficient of friction, a technique for reducing the coefficient of friction has been known conventionally with an additive called a lubricant. However, there is a problem in that the lubricant in the volume of these films is coagulated and solidified over time, brimming on the film surface, and differentiating. The differentiated lubricant acts as an external scattering agent and impairs the transparency of the plastic house. In addition, since the elastic modulus of the film is lowered, even if the sliding is good, a problem is caused by an external action accompanying deformation.

In addition, the method of imparting irregularities to the film surface with an anti-blocking agent is also effective as a means to prevent frictional breakage, but it is necessary to make irregularities of about several μm in order to exhibit the effect, and at the same time, as an external scattering body, vinyl It hinders the transparency of the house.

As a method without using additives, high-density polyethylene (HDPE) or ultra-high molecular weight polyethylene (UHMWPE), which exhibits low coefficient of friction characteristics, can be used as a single layer film, but in the case of HDPE, crystallinity is high and the stretching orientation at the time of film formation Accordingly, since the tear strength in a specific direction is low, the breakage easily propagates. In addition, since crystal phases having different refractive indexes and abnormalities are mixed, the transparency is also low. Moreover, in the case of UHMWPE, since it has a high molecular weight, there is a problem that the melt viscosity is high, the workability is remarkably poor when forming a film, and further, voids are generated. In this way, it was difficult to impart a slip property without impairing the mechanical strength such as transparency and tear strength.

For example, Patent Document 1 discloses a method of blending two types of polyethylene having different densities as a technique for preventing blocking at the time of winding about the surface protective film of an optical film.

In addition, Patent Document 2 discloses a method of providing irregularities as a method of reducing the frictional sound between bags of a packaging film.

In addition, Patent Document 3 discloses a technique for expressing sealing properties by adding a lubricant to a polyethylene sealant material.

Japanese Unexamined Patent Publication No. 2005-28619 Japanese Unexamined Patent Publication No. 2000-169598 Japanese Laid-Open Patent Publication No. 2016-49727

However, Patent Document 1 has a problem that, due to the property of a protective film, sufficient strength to maintain strength in a long-term use environment cannot be expressed.

In addition, Patent Document 2 has a problem that sufficient transparency is not obtained.

In addition, Patent Document 3 has a problem that transparency decreases due to long-term use due to surface segregation of the lubricating material component.

In addition, for example, in the case of processing a thin film having a thickness of 200 µm or less, it has been difficult to obtain a film having sufficient transparency and resistant to friction.

The present invention has been made in view of these points. Accordingly, it is an object of the present invention to provide a polyethylene-based resin composition and a polyethylene-based film that ensure sufficient transparency even under a long-term heating environment and are resistant to friction.

The present inventors have found that it is effective to reduce the coefficient of friction and to reduce the coefficient of dynamic friction relative to the coefficient of static friction as a method of improving the slip properties of a resin without using a lubricant or an anti-blocking agent. On the basis of this knowledge, the present invention has been reached.

That is, the present invention is as follows.

(1) It has a density of 0.920 to 0.950 g/cm 3, and both the dynamic friction coefficient D and the static friction coefficient S are 0.30 or less, and the ratio D/S of the dynamic friction coefficient D to the static friction coefficient S is 1.0 A polyethylene resin composition characterized by the following.

(2) The polyethylene-based resin composition according to (1), comprising a polyethylene component (A) and a polyethylene component (B) showing different tensile modulus of elasticity.

(3) The polyethylene-based resin composition according to (2), wherein the polyethylene component (A) contains linear low-density polyethylene, and the polyethylene component (B) contains ultra-high molecular weight polyethylene.

(4) The polyethylene-based resin according to (3), containing 50 to 99.9 mass% of the polyethylene component (A) and 0.1 to 50 mass% of the polyethylene component (B) relative to 100 mass% of the polyethylene resin composition. Composition.

(5) The polyethylene resin composition according to any one of (1) to (4), wherein a tensile modulus of elasticity measured in accordance with JIS K7127 is 0.35 GPa or more.

(6) The polyethylene-based resin composition according to any one of (1) to (5), wherein the internal haze in the 150 µm-thick film measured in accordance with JIS K7136 is 45 or less.

(7) A polyethylene-based film comprising a surface layer made of the polyethylene-based resin composition according to any one of (1) to (6).

(8) The polyethylene-based film according to (7), further comprising an adhesive layer laminated on the surface layer.

(9) The polyethylene film according to (7) or (8) for agricultural use.

Advantageous Effects of Invention According to the present invention, a polyethylene-based resin composition and a polyethylene-based film can be obtained which ensures sufficient transparency even under a heating environment for a long time and resists friction.

Hereinafter, an embodiment for carrying out the present invention (hereinafter, simply referred to as "this embodiment") will be described in detail. The embodiments described below are examples for explaining the present invention, and are not intended to limit the present invention to the following contents. The present invention can be implemented by appropriately deforming within the scope of the gist.

<Polyethylene resin composition>

The polyethylene resin composition of the present embodiment has a density of 0.920 to 0.950 g/cm 3, and both the dynamic friction coefficient D and the static friction coefficient S are 0.30 or less, and the ratio of the dynamic friction coefficient D to the static friction coefficient S D/S is 1.0 or less.

According to one aspect of the present embodiment, it is preferable that the polyethylene-based resin composition of the present embodiment contains a polyethylene component (A) and a polyethylene component (B) exhibiting different tensile modulus of elasticity in obtaining the frictional properties. .

Hereinafter, the resin composition of the aspect containing a polyethylene component (A) and a polyethylene component (B) is explained in full detail.

<Polyethylene component (A)>

As the polyethylene component (A) contained in the polyethylene resin composition of the present embodiment, polyethylene excellent in transparency and mechanical strength can be preferably used. As such polyethylene, a high pressure method low density polyethylene (LDPE) and a low pressure method low density polyethylene (LLDPE) are mentioned, for example. In addition, the polyethylene component (A) may be a single type or a combination of two or more types.

LDPE has better molding processability and transparency than other polyethylenes, and is flexible. However, since orientation is easily applied, tear strength, impact, and tensile strength are weak.

Although it does not specifically limit as LDPE, For example, as a commercial item, Suntec LD (manufactured by Asahi Chemical Co., Ltd.), UBE polyethylene (manufactured by Ube Maruzen Polyethylene Corporation), Petrosen (manufactured by Tosoh Corporation) and the like can be mentioned. Among these, Suntec LD is preferable. The density of LDPE is preferably 0.910 to 0.930 g/cm 3, and more preferably around 0.920 g/cm 3, from the viewpoint of achieving both transparency and rigidity.

LLDPE is more preferable from the viewpoint of transparency and mechanical strength.

LLDPE may be a homopolymer of ethylene, or a copolymer of ethylene and another α-olefin (ethylene-α-olefin copolymer). Moreover, you may use what added a modifying resin to these copolymers.

The density of LLDPE is preferably 0.880 to 0.945 g/cm 3, and more preferably 0.910 to 0.940 g/cm 3, from the viewpoint of achieving both transparency and rigidity.

The ethylene-α-olefin copolymer in the present disclosure is a random copolymer of ethylene and at least one α-olefin monomer selected from α-olefins having 3 to 18 carbon atoms. Examples of the α-olefin include propylene, butene-1, pentene-1, 4-methylpentene-1, hexene-1, octene-1, decene-1, and dodecene-1. Among these, hexene-1 is preferable.

The ethylene-?-olefin copolymer can be polymerized by a method such as living polymerization or chain polymerization.

The polymerization catalyst used in the production of the ethylene-?-olefin copolymer is not particularly limited, but a multisite catalyst, a single site catalyst, or the like can be mentioned. From the viewpoint of improving the slipperiness of the film surface, a single site system is preferable.

The ethylene content in the ethylene-α-olefin copolymer is preferably 40 to 95% by mass, more preferably 50 to 90% by mass, still more preferably 60 to 85% by mass, from the viewpoint of improving sealing properties and transparency. to be.

<Content of polyethylene component (A)>

The content of the polyethylene component (A) is preferably 50 to 99.9% by mass, more preferably 55 to 95% by mass, and still more preferably 60 to 90% by mass with respect to 100% by mass of the polyethylene resin composition. When the content of the polyethylene component (A) is 50 to 99.9% by mass, transparency can be improved.

<Tensile modulus of the polyethylene component (A)>

The tensile modulus of the polyethylene component (A) is preferably 0.1 to 0.45 GPa, more preferably 0.2 to 0.45 GPa.

In addition, in the present disclosure, the tensile modulus of the polyethylene component (A) is a value measured according to JIS K7127.

<Polyethylene component (B)>

The polyethylene component (B) contained in the polyethylene resin composition of the present embodiment refers to a polyethylene component exhibiting elastic modulus characteristics different from that of the polyethylene component (A).

By kneading the polyethylene component (B) with the polyethylene component (A) and dispersing it uniformly, the coefficient of dynamic friction of the polyethylene resin composition can be reduced.

As the polyethylene component (B), high-density polyethylene (HDPE) and ultra-high molecular weight polyethylene (UHMWPE) are mentioned, for example. By blending HDPE and UHMWPE, it is possible to obtain a polyethylene resin composition having a low coefficient of friction because there are few terminal branches that become adhesive points.

In addition, the polyethylene component (B) may be a single type, or a combination of two or more types. In particular, by blending UHMWPE into the polyethylene component (B), crystallization of other low molecular weight polyethylene can be suppressed, and internal haze can be reduced.

Further, by blending UHMWPE, the long molecular chains of UHMWPE are dispersed in the form of inserting the polyethylene component (A), and the resin composition exhibits a higher modulus of elasticity than a simple caustic average.

Although it does not specifically limit as HDPE, For example, as a commercial item, Suntec HD (made by Asahi Hwaseong Corporation), Novatech HD (made by Nippon Polyethylene Corporation), Hi-Jex (made by Prime Polymer Corporation), etc. are mentioned. Among these, Suntec HD is preferable. The density of HDPE is preferably from 0.950 to 0.980 g/cm 3, and more preferably from 0.960 to 0.970 g/cm 3.

Although it does not specifically limit as UHMWPE, The homopolymer of ethylene, or the copolymer of ethylene and another monomer is mentioned. Although it does not specifically limit as another monomer, For example, α-olefins, such as propylene, butene-1, hexene-1, and octene-1; Vinyl compounds, such as vinyl acetate; Acrylic acid, methacrylic acid, acrylic ester, methacrylic acid (Meth)acrylic compounds such as esters are mentioned. Among these, as a homopolymer of ethylene and a copolymer of ethylene and another ?-olefin, a copolymer containing 90 mol% or more of ethylene monomer units is preferable.

In particular, when UHMWPE having an intrinsic viscosity [η] of 5 dl/g or more and 40 dl/g or less is used, a molded article excellent in high strength, abrasion resistance, self-lubrication, hygiene, and chemical resistance, etc., can be obtained.

The intrinsic viscosity [η] of UHMWPE is preferably 5 dl/g or more, more preferably 8 dl/g or more, and still more preferably 15 dl/g or more. When the intrinsic viscosity [η] of UHMWPE is 5 dl/g or more, the abrasion resistance and sliding properties of the obtained molded article are further improved. Further, UHMWPE having an intrinsic viscosity of 5 dl/g or more tends not to disperse well under normal kneading conditions, but if it is a polyethylene resin composition of the present embodiment, it will contain UHMWPE with good dispersibility. On the other hand, when the intrinsic viscosity [η] of UHMWPE is less than 5 dl/g, the molecular weight of the entire resin contained in the polyethylene-based resin composition is too low, which deteriorates properties such as abrasion resistance and sliding properties, which are one of the original characteristics of UHMWPE. .

The intrinsic viscosity [η] of UHMWPE is preferably 40 dl/g or less, more preferably 30 dl/g or less, and still more preferably 25 dl/g or less. When the intrinsic viscosity of UHMWPE is 40 dl/g or less, the productivity in the production process of UHMWPE is further improved.

The intrinsic viscosity [η] of UHMWPE can be adjusted by adding hydrogen as a chain transfer agent in the polymerization system of UHMWPE or by changing the polymerization temperature. In addition, the intrinsic viscosity is a value measured in decalin (decahydronaphthalene) at 135°C according to ISO 1628-3.

Although it does not specifically limit as a catalyst used for manufacture of UHMWPE, Ziegler-Natta catalyst is preferable.

<Content of polyethylene component (B)>

The content of the polyethylene component (B) is preferably 0.1 to 50% by mass, more preferably 10 to 45% by mass, and still more preferably 20 to 40% by mass with respect to 100% by mass of the polyethylene-based resin composition. Haze can be lowered when the content of the polyethylene component (B) is 0.1 to 50 mass%.

<Tensile modulus of the polyethylene component (B)>

The tensile modulus of the polyethylene component (B) is preferably 0.3 to 0.8 GPa, more preferably 0.34 to 0.7 GPa.

In addition, in this disclosure, the tensile modulus of the polyethylene component (B) is a value measured according to JIS K7127.

<Other ingredients>

The polyethylene resin composition of the present embodiment requires, for example, stabilizers such as heat stabilizers and weathering agents, coloring agents such as pigments and dyes, crosslinking agents, crosslinking aids, antifogging agents, fillers such as organic and inorganic fillers, and other resins. You may add according to.

It is preferable that it is 0.01-20 mass %, and, as for content of the said additive, it is more preferable that it is 0.1-10 mass% with respect to 100 mass% of a polyethylene-type resin composition.

Hereinafter, the characteristics of the polyethylene resin composition of the present embodiment will be described.

<Density of polyethylene resin composition>

The density of the polyethylene-based resin composition is 0.920 to 0.950 g/cm 3, preferably 0.930 to 0.950 g/cm 3, and more preferably 0.940 to 0.950 g/cm 3. When the density of the polyethylene-based resin composition is 0.920 to 0.950 g/cm 3, a composition in which transparency and slipperiness are compatible can be obtained.

In addition, in the present disclosure, the density of the polyethylene resin composition is a value measured according to JIS K7112.

<Molecular weight of polyethylene resin composition>

In the polyethylene resin composition, from the viewpoint of scratch resistance, it is preferable that a component having a weight average molecular weight of 600,000 or more occupies an area of 5% or more of the total peak area of the polyethylene resin composition at the time of GPC (gel permeation chromatography) measurement, More preferably, it is 10% or more.

In addition, in the present disclosure, the weight average molecular weight of the polyethylene resin composition can be measured by high temperature GPC.

<Static friction coefficient S and dynamic friction coefficient D of polyethylene resin composition>

As a property of friction, the static friction coefficient S and the dynamic friction coefficient D are known.

The static friction coefficient S is a value relating to an adhesion phenomenon caused by intermolecular force and atomic force between substances, and is calculated by the maximum point that imparts a distortion that separates the bound energy.

On the other hand, the coefficient of dynamic friction D is also equivalent in that it is calculated by the maximum point that imparts a distortion that separates the bonded energy from adhesion due to intermolecular and atomic forces between substances. However, since there are always irregularities on the surface of a general real object, the dynamic friction coefficient D at which the contact area decreases is generally small.

However, in the case of a resin having viscoelastic properties such as polyethylene, due to the viscous properties of the resin, for a resin having a viscous property with a long relaxation time, the time to recover the distortion caused by deformation becomes longer, and the center of gravity of the body is always Since the negative load is applied in the opposite direction to the movement, the dynamic friction coefficient D increases.

From these findings, in order to reduce the static friction coefficient S, it is preferable to blend high-density polyethylene (HDPE) or ultra-high molecular weight polyethylene (UHMWPE) having a small number of adhesion points.

In addition, in order to suppress deformation due to viscosity and lower the dynamic friction coefficient D, it is preferable that the polyethylene layer containing two or more types of polyethylene has a high elastic modulus.

The dynamic friction coefficient D and the static friction coefficient S of the polyethylene-based resin composition of the present embodiment are both preferably 0.30 or less, preferably 0.25 or less, and more preferably 0.21 or less. If the coefficient of dynamic friction D and the coefficient of static friction S are 0.30 or less, one having high resistance to repeated frictional failure is obtained. Moreover, the dynamic friction coefficient D and the static friction coefficient S may be 0.08 or more, and it is preferable that they are 0.1 or more.

Moreover, the ratio D/S of the dynamic friction coefficient D to the static friction coefficient S is 1.0 or less, it is preferable that it is 0.95 or less, and it is more preferable that it is 0.9 or less. When D/S is 1.0 or less, one having high resistance to repeated frictional failure is obtained. Moreover, D/S may be 0.5 or more, and it is preferable that it is 0.6 or more.

In addition, in the present disclosure, the coefficient of dynamic friction D and the coefficient of static friction S of the polyethylene-based resin composition are values measured according to JIS K7125.

<Tensile modulus of the polyethylene resin composition>

It is preferable that it is 0.35 GPa or more, and, as for the tensile modulus of the polyethylene resin composition of this embodiment, it is more preferable that it is 0.4 GPa or more. When the tensile modulus of elasticity is 0.35 GPa or more, the distortion due to deformation is small, and the time for recovering the distortion can be shortened, and thus it is preferable that the jam causing the frictional breakage is less likely to occur.

In addition, in the present disclosure, the tensile modulus of the polyethylene resin composition is a value measured according to JIS K7127.

<Internal haze of polyethylene resin composition>

The internal haze of the polyethylene-based resin composition is preferably 45 or less, more preferably 35 or less, and still more preferably 30 or less in a 150 µm-thick film. When the internal haze is 45 or less, it is preferable because it can be preferably used as a transparent film.

In addition, in the present disclosure, the internal haze of the polyethylene-based resin composition is a value excluding haze derived from a surface structure such as irregularities, and is measured in accordance with JIS K7136.

<Production method of polyethylene resin composition>

The production method of the polyethylene-based resin composition of the present embodiment is not particularly limited, but when the polyethylene component (B) contains UHMWPE, the production method of the following example is preferable.

In addition, when the polyethylene component (B) does not contain UHMWPE, it can be kneaded using ordinary kneading conditions to prepare a polyethylene-based resin composition.

An example of the method for producing the polyethylene-based resin composition of the present embodiment in the case where the polyethylene component (B) contains UHMWPE is a component that does not contain UHMWPE in the polyethylene component (A) or the polyethylene component (B) (this In the specification, a part of the ``polyethylene component (B) not containing UHMWPE'' is sometimes simply referred to as) and the component containing UHMWPE in the polyethylene component (B) (in this specification, simply ``the UHMWPE polyethylene component ( B)'') is melt-kneaded to obtain a high-concentration dilution of the polyethylene-based resin composition, and the polyethylene-based resin composition high-concentration dilution and the polyethylene component (A) or polyethylene containing no UHMWPE A second melt-kneading step of melt-kneading a part of the component (B) to obtain a polyethylene-based resin composition intermediate, and a part of the polyethylene-based resin composition intermediate and the polyethylene component (A) or a polyethylene component (B) not containing UHMWPE It has a 3rd and subsequent melt-kneading process for melt-kneading to obtain a polyethylene-based resin composition.

Thus, a high-concentration dilution of the polyethylene component (A) or a portion of the polyethylene component (B) not containing UHMWPE and the UHMWPE polyethylene component (B) is made, and the same or different polyethylene component (A) or By further adding a part of the polyethylene component (B) not containing UHMWPE and performing melt-kneading multiple times, the resulting polyethylene-based resin composition can be controlled to have the above properties.

[1st melt-kneading process]

The first melt-kneading step is a step of melt-kneading a part of the polyethylene component (A) or the polyethylene component (B) not containing UHMWPE and the UHMWPE polyethylene component (B) to obtain a polyethylene-based resin composition high-concentration dilution.

As for the polyethylene component (A) or a part of the polyethylene component (B) not containing UHMWPE, and the UHMWPE polyethylene component (B), the same ones as described above can be used. Moreover, the polyethylene component (A) and the polyethylene component (B) may be used individually by 1 type, respectively, and may use 2 or more types together.

Although it does not specifically limit as a melt-kneading means, For example, known kneading means, such as a single screw extruder, a multi-screw extruder, such as a twin screw, and a Banbury mixer, are mentioned. According to the conventional way of thinking, as a means of melt-kneading, for example, a method of mechanically kneading by strengthening shear force by forming a kneading reinforcing part such as a dulmaeji, a pin, a kneading disk, and a reverse screw on the screw of an extruder is used. do. However, from the viewpoint of avoiding the cleavage of the molecular chains of UHMWPE in the polyethylene component (B) by excessively strengthening the shearing force, it is preferable to suppress the use of the screw forming these shearing force strengthening sites to the extent that it does not become excessive. From such a viewpoint, as the melt-kneading means, a full flight screw or a kneading means including a screw having a slight shear force strengthening portion is preferably used.

In the first melt-kneading step, it is preferable that UHMWPE in the polyethylene component (B) is stirred in a relatively high-viscosity atmosphere, whereby long-chain molecules that do not move easily are diffused. From the viewpoint of improving the driving force for diffusing the molecular chain of UHMWPE in the polyethylene component (B), the molecular weight of a part of the polyethylene component (A) to be used or the polyethylene component (B) not containing UHMWPE is preferably relatively low. . In addition, from the viewpoint of improving the driving force for diffusing the molecular chain of UHMWPE in the polyethylene component (B), the overall viscosity of the system in the first melt-kneading step is preferably high, and the temperature is preferably adjusted so that the viscosity increases. .

The melt mass flow rate (MFR) of a part of the polyethylene component (A) or the polyethylene component (B) not containing UHMWPE used in the first melt-kneading step is preferably 0.1 to 800 dg/min, more preferably It is 1 to 700 dg/min, more preferably 10 to 600 dg/min. When the MFR of a part of the polyethylene component (A) or the polyethylene component (B) not containing UHMWPE used in the first melt-kneading step is within the above range, the dispersibility of the UHMWPE polyethylene component (B) tends to be further improved. .

In addition, in this disclosure, the melt mass flow rate is a value measured at 200° C. and a load of 49 N in accordance with ISO 1133.

The amount of the UHMWPE polyethylene component (B) added in the first melt-kneading step is not particularly limited, but with respect to the total amount of the polyethylene component (B) and the polyethylene component (A) used in the first melt-kneading step, preferably It is 30 to 90 mass %, More preferably, it is 40 to 80 mass %, More preferably, it is 50 to 70 mass %. When the amount of the UHMWPE polyethylene component (B) added in the first melt-kneading step is 30% by mass or more, the overall viscosity of the system is higher, and the driving force for diffusing the molecular chain of UHMWPE is further improved, resulting in a difference in refractive index. The size of the lumps observed is smaller and the number tends to decrease. Moreover, when the addition amount of the UHMWPE polyethylene component (B) in the 1st melt-kneading process is 90 mass% or less, the load on a kneading apparatus tends to be further reduced.

The temperature in the first melt-kneading step is preferably 150 to 260°C, more preferably 160 to 250°C, and still more preferably 170 to 240°C. When the temperature in the first melt-kneading step is 150°C or higher, the ease of movement of the UHMWPE polyethylene component (B) can be improved, and the dispersion of the UHMWPE polyethylene component (B) tends to be promoted. In addition, when the temperature in the first melt-kneading step is 260°C or less, the overall viscosity of the system is increased to promote dispersion of the UHMWPE polyethylene component (B), and furthermore, the molecular weight due to thermal decomposition of the UHMWPE polyethylene component (B) There is a tendency that the decrease can be further suppressed and the decrease in the strength of the resulting molded article can be more suppressed.

The kneading time in the first melt-kneading step is also different depending on the kneading device to be used, but is preferably 0.5 to 20 minutes, more preferably 1 to 10 minutes, and still more preferably 2 to 8 minutes. When the kneading time in the first melt-kneading step is 0.5 minutes or more, the size of the mass observed due to the difference in refractive index tends to be smaller, and the number thereof tends to decrease. Further, since UHMWPE has a slow motion due to its large molecule, UHMWPE tends to be more dispersed when the kneading time in the first melt-kneading step is 0.5 minutes or more. Moreover, since the kneading time in the 1st melt-kneading process is 20 minutes or less, it is economically preferable. In addition, the 1st melt-kneading process may be performed once and may be kneaded multiple times.

[2nd melt-kneading process]

The second melt-kneading step is a step of melt-kneading a polyethylene-based resin composition high-concentration dilution and a part of the polyethylene component (A) or the polyethylene component (B) not containing UHMWPE to obtain a polyethylene-based resin composition intermediate. The 2nd melt-kneading process may be performed once or may be performed multiple times. Moreover, 2nd melt-kneading may be performed by the same apparatus as a 1st melt-kneading process, and may be performed by a different apparatus.

Although it does not specifically limit as a melt-kneading means, For example, it can make it the same as a 1st melt-kneading process.

The content of the UHMWPE polyethylene component (B) in the polyethylene-based resin composition intermediate obtained in the second melt-kneading process varies depending on the required physical properties of the target product, but is preferably 20 to 80 mass%, more preferably It is 30 to 70 mass%, More preferably, it is 40 to 60 mass%. When the content of the UHMWPE polyethylene component (B) in the polyethylene-based resin composition intermediate obtained in the second melt-kneading step is 20% by mass or more, the viscosity of the entire system is higher, and the driving force for diffusing the molecular chain of UHMWPE is further improved, As a result, the size of the lumps observed due to the difference in refractive index becomes smaller, and the number tends to decrease. In addition, when the amount of the UHMWPE polyethylene component (B) added in the second melt-kneading step is 80% by mass or less, the load on the kneading device is further reduced, and thus the discharge amount can be increased, and as a result, economically improved. There is a tendency.

Part of the polyethylene component (A) used in the second melt-kneading step or the polyethylene component (B) not containing UHMWPE is the polyethylene component (A) used in the first melt-kneading step or the polyethylene component (B) not containing UHMWPE ) May be the same as or different.

The MFR of a part of the polyethylene component (A) or the polyethylene component (B) not containing UHMWPE used in the second melt-kneading step is preferably 0.1 to 800 dg/min, more preferably 0.5 to 500 dg/min. And more preferably 1 to 200 dg/min. The viscosity of the entire system in the second melt-kneading process is further improved by having an MFR of 800 dg/min or less of the polyethylene component (A) used in the second melt-kneading process or the polyethylene component (B) not containing UHMWPE. As a result, there is a tendency that the dispersion of the resin in the highly concentrated dilution of the polyethylene resin composition can be further promoted.

In addition, the MFR of a part of the polyethylene component (A) used in the second melt-kneading step or the polyethylene component (B) not containing UHMWPE does not contain the polyethylene component (A) or UHMWPE used in the first melt-kneading step. It is preferred that the MFR of some of the non-polyethylene component (B) is equal to or lower than. Thereby, the viscosity of the system in the second melt-kneading step can be increased, and as a result, there is a tendency to obtain a small size or a small number of lumps observed due to the difference in refractive index. The MFR of the polyethylene component (A) used in the second melt-kneading process or the polyethylene component (B) not containing UHMWPE is a polyethylene component (A) used in the first melt-kneading process or polyethylene that does not contain UHMWPE. The MFR of a part of the component (B) is preferably 1 times or less, more preferably 0.5 times or less, and still more preferably 0.3 times or less. MFR of the polyethylene component (A) used in the second melt-kneading step or the polyethylene component (A) of the polyethylene component (B) not containing UHMWPE used in the first melt-kneading step or the polyethylene component not containing UHMWPE ( When it is 1 times or less of the MFR of a part of B), the viscosity of the whole system in the second melt-kneading step is more improved, and dispersion of the resin in the high-concentration dilution of the polyethylene-based resin composition tends to be further promoted.

The amount of the polyethylene-based resin composition high-concentration dilution used in the second melt-kneading step and a portion of the polyethylene component (A) or the polyethylene component (B) not containing UHMWPE is the UHMWPE polyethylene component ( It is also different depending on the content of B), and can be appropriately determined in consideration of the final concentration of the UHMWPE polyethylene component (B) from which physical properties of the target film are obtained, and fluidity required to produce the target film.

The temperature at the time of melt-kneading in the second melt-kneading step is preferably 150 to 250°C, more preferably 150 to 240°C, and still more preferably 150 to 230°C. When the temperature at the time of melt-kneading in the second melt-kneading step is 250°C or less, the overall viscosity of the system is improved and the dispersion of the polyethylene-based resin composition high-concentration dilution tends to be further improved. In addition, when the temperature at the time of melt-kneading in the second melt-kneading step is 250°C or less, it is possible to suppress a decrease in molecular weight due to thermal decomposition of UHMWPE in the UHMWPE polyethylene component (B), and the resulting film strength decreases. Tends to be more restrained. Moreover, when the temperature at the time of melt-kneading in the second melt-kneading step is 150°C or higher, the ease of movement of the UHMWPE polyethylene component (B) can be improved, and the dispersion of the UHMWPE polyethylene component (B) tends to be promoted.

[3rd melt-kneading process]

The third melt-kneading step is a step of melt-kneading a part of the polyethylene-based resin composition intermediate obtained in the second melt-kneading step and a polyethylene component (A) or a polyethylene component (B) not containing UHMWPE to obtain a polyethylene-based resin composition. to be.

The 3rd melt-kneading may be performed by the same apparatus as the 1st, 2nd melt-kneading process, and may be performed by a different apparatus. Although it does not specifically limit as a melt-kneading means, For example, it can make it the same as a 1st melt-kneading process.

Part of the polyethylene component (A) used in the third melt-kneading step or the polyethylene component (B) not containing UHMWPE is the polyethylene component (A) used in the first and second melt-kneading steps, or polyethylene containing no UHMWPE. It may be the same as or different from a part of the component (B). The MFR of a part of the polyethylene component (A) or the polyethylene component (B) not containing UHMWPE used in the third melt-kneading step can be appropriately selected according to the fluidity and strength required by the intended use.

The MFR of a part of the polyethylene component (A) or the polyethylene component (B) not containing UHMWPE used in the third melt-kneading step is preferably 0.1 to 800 dg/min, more preferably 0.5 to 500 dg/min. And more preferably 1 to 200 dg/min. The overall viscosity of the system in the third melt-kneading process is further improved by having an MFR of 800 dg/min or less of the polyethylene component (A) used in the third melt-kneading process or the polyethylene component (B) not containing UHMWPE. As a result, there is a tendency that dispersion of the polyethylene-based resin composition intermediate can be further promoted.

The amount of the polyethylene-based resin composition intermediate used in the third melt-kneading step and a portion of the polyethylene component (A) or the polyethylene component (B) not containing UHMWPE is the content of the UHMWPE polyethylene component (B) in the polyethylene-based resin composition intermediate. It is also different depending on the material, and can be appropriately determined in consideration of the final concentration of the UHMWPE polyethylene component (B) from which physical properties of the target film are obtained, the fluidity required to produce the target film, and the like.

The temperature at the time of melt-kneading in the third melt-kneading step is preferably 150 to 260°C, more preferably 160 to 250°C, and still more preferably 170 to 240°C. When the temperature at the time of melt-kneading in the third melt-kneading step is 260°C or less, the overall viscosity of the system is improved, and the dispersion of the polyethylene-based resin composition intermediate tends to be further improved. In addition, when the temperature at the time of melt-kneading in the third melt-kneading step is 260°C or less, a decrease in molecular weight due to thermal decomposition of UHMWPE in the UHMWPE polyethylene component (B) can be suppressed, and the resulting film strength decreases. Tends to be more restrained. In addition, when the temperature at the time of melt-kneading in the third melt-kneading step is 150°C or higher, the mobility of the UHMWPE polyethylene component (B) can be improved, and the dispersion of the UHMWPE polyethylene component (B) tends to be promoted.

In addition to this, it is also possible to form a fourth or subsequent melt-kneading step as necessary. The 4th and subsequent melt-kneading steps can be performed under the same operation and conditions as the third melt-kneading step.

The first melt-kneading step and the second and third or fourth melt-kneading steps may be performed as separate steps, or a device for performing the second and subsequent melt-kneading steps to the device for performing the first melt-kneading step The first melt-kneading step and the second and subsequent melt-kneading steps may be continuously performed by connecting the polyethylene component (A) or the polyethylene component (B) not containing UHMWPE during the kneading of a device for melt-kneading a high-concentration diluted product. You may perform the 1st melt-kneading process and the 2nd and subsequent melt-kneading process continuously by side-feeding a part of. In either case, it is preferable to melt-kneaded in consideration of temperature conditions and the like so that the above-described UHMWPE polyethylene component (B) and the polyethylene-based resin composition high-concentration dilution and the polyethylene-based resin composition intermediate are sufficiently dispersed in each step.

In performing the kneading, the effect of lowering the apparent melt viscosity is obtained by using a processing aid or the like. When the processing aid is not added, operation is performed at a specific temperature under the condition of the torque limit of the device, whereas when the processing aid is added, the resin pressure during extrusion is lowered. Becomes possible.

In particular, in the second kneading, for the purpose of accelerating the dispersion of the UHMWPE polyethylene component (B), it is preferable to knead at a low temperature as possible, and it is preferable to add these processing aids.

As the processing aid, a PVDF system (manufactured by 3M, Dynamar FX5920) or an acrylic modified PTFE system (manufactured by Mitsubishi Rayon, Metablen A3000) can be preferably used. At the time of use, it is preferable to add and use in the range of 0.01 to 1.0 mass% with respect to 100 mass% of the polyethylene-type resin composition before the 1st melt-kneading process.

<Polyethylene film>

The polyethylene resin composition of the present embodiment can be variously molded, such as a film or a sheet, by known molding methods such as extrusion molding and injection molding.

The polyethylene-based film molded from the polyethylene-based resin composition of the present embodiment may be a single layer or a part of a multilayer film. The thickness of the polyethylene-based film is preferably 10 to 200 µm, more preferably 50 to 180 µm, and still more preferably 90 to 160 µm.

The polyethylene-based film of the present embodiment may have a surface layer made of the polyethylene-based resin composition of the present embodiment described above, and may optionally further have an adhesive layer laminated on the surface layer on one side of the surface layer.

In addition, the adhesive layer in this disclosure is a layer for temporarily or semi-permanently bonding the present polyethylene-based film with another material.

The static friction coefficient S and dynamic friction coefficient D, density, tensile modulus, and internal haze of the polyethylene-based film of the present embodiment are the same as those of the polyethylene-based resin composition described above.

<Forming method of polyethylene film>

The polyethylene-based film of the present embodiment is obtained by extrusion molding the polyethylene-based resin composition obtained by the above. Although it does not specifically limit as an extrusion molding method, T-die molding, inflation molding, hot press molding, vacuum molding, etc. are mentioned. Among them, inflation molding is preferred. The processing temperature is preferably 150 to 250°C, more preferably 160 to 230°C, and still more preferably 170 to 220°C.

Moreover, the polyethylene-based film of this embodiment may perform a crosslinking reaction after film formation. By crosslinking reaction, a polyethylene layer having a higher molecular weight can be obtained, and a film having improved slip and wear properties can be obtained.

Example

Hereinafter, the present invention will be described in more detail by examples, but the present invention is not limited to the following examples.

<Materials used in Examples and Comparative Examples>

In the production of a polyethylene resin composition, the polyethylene used as the polyethylene component (A) is as follows.

LLDPE1: Prime Polymer, Evols (registered trademark) SP4020 (density: 0.937 g/cm3, tensile modulus: 0.45 GPa)

LLDPE2: Ubekosan, Umerit (registered trademark) 631J (density: 0.931 g/cm3, tensile modulus: 0.29 GPa)

LLDPE3: Ubekosan, Umerit (registered trademark) 2040FC (density: 0.919 g/cm3, tensile modulus: 0.21 GPa)

In production of a polyethylene resin composition, the polyethylene used as the polyethylene component (B) is as follows.

UHMWPE1: Sunfine (registered trademark) UH900 (Density: 0.940 g/cm3, Tensile Modulus: 0.34 GPa) manufactured by Asahi Hwaseong Corporation

HDPE1: manufactured by Asahi Hwaseong, Suntec (registered trademark) J300 (density: 0.961 g/cm 3, tensile modulus: 0.68 GPa)

HDPE2: manufactured by Asahi Hwaseong, Suntec (registered trademark) J240 (density: 0.966 g/cm3, tensile modulus: 0.7 GPa)

The processing aid used in the manufacture of the polyethylene resin composition is as follows.

Processing aid 1: Acrylic modified PTFE system (Mitsubishi Rayon Co., Ltd., Metablen A3000)

(1) Measurement of density

The density (g/cm 3) of the polyethylene resin composition was measured by the D method (density gradient pipe) according to JIS K7112. Table 1 shows the measurement results.

(2) Measurement of static friction coefficient S and dynamic friction coefficient D

The static friction coefficient S and the dynamic friction coefficient D of the polyethylene resin composition were measured according to JIS K7125 with a load of 500 g of SUS by Friction TESTER TR (manufactured by Toyo Seiki Corporation). Table 1 shows the measurement results.

(3) Measurement of tensile modulus

The tensile modulus (GPa) of the polyethylene-based resin composition was measured in accordance with JIS K7127 with an autograph AG-XPlus (manufactured by Shimadzu Corporation) with a distance between the chucks of 50 mm. Table 1 shows the measurement results.

(4) Measurement of internal haze

The internal haze of the polyethylene-based resin composition is dimethyl silicone oil (Toray Dow Corning, SH-200 (100 cs: mm 2 /s)) on the surface of a 150 µm-thick polyethylene-based film molded from the polyethylene-based resin composition. After application, it measured according to JIS K7136 by HAZE METER NDH-5000 (made by Nippon Denshoku Industries, Ltd.). Table 1 shows the measurement results.

(5) Friction failure test

The polyethylene-based film was subjected to a frictional failure test using a fastness tester (manufactured by Taiei Science Co., Ltd., RT-200). A friction ruler made of stainless steel (SUS304) having a rectangular shape with a contact surface of 14 mm×1 mm was used, and under a load of 190 g (13.3 N/cm 2) in weight, a 12 cm reciprocation was performed 100 times. After completion, it evaluated by the following criteria by visual observation.

○ (Good): There are marks on the surface, but the surface of the film is not cut off.

× (Defect): The surface is dug up and the friction scratches of irregularities are strong.

(6) Measurement of molecular weight

The weight average molecular weight of the polyethylene resin composition was measured under the following conditions using gel permeation chromatography (GPC).

-Sample adjustment: Eluent TCB (0.05% 4,4'-thiobis (containing 6-t-butyl-3-methylphenol) was added to the polyethylene resin composition), and the concentration was set to 300 ppm by mass, at 160°C for 30 minutes. After stopping still, it was shaken for 1 hour to dissolve the resin composition.

Equipment: PL-GPC220 manufactured by Agilent Corporation

Detector: RI

Column: TSKgel GMH _HR -H(20) HT (7.8 nnl. D × 30 cm) 2

Equipment temperature: 160 ℃ for the whole flow

Sample amount: 500 µl

In the obtained GPC elution curve, a baseline was drawn and the peak of the polyethylene-based resin composition was designated. Next, polystyrene (Easical PS-1, manufactured by Agilent) was used to create a molecular weight calibration curve, and the molecular weight of the polyethylene resin composition was determined. In the peak of the polyethylene-based resin composition, a component having a holding time of 22.35 minutes or less was used as a component having a molecular weight of 600,000 or more, and the ratio of the component having a molecular weight of 600,000 or more in the entire area of the peak was determined. Table 1 shows the results.

[Example 1]

After mixing 55.5 mass% of UHMWPE1 and 44.5 mass% of HDPE1, they were melt-kneaded with a Toshiba Machinery Co., Ltd. TEM-18ss twin screw extruder (L/D = 50). The kneading was carried out by adjusting the feeder so that the discharge amount was about 1 to 2 kg/Hr at temperature = 215°C and screw rotation speed = 200 rotations to obtain a polyethylene-based resin composition high-concentration dilution.

After mixing 66.7 mass% of the polyethylene resin composition high-concentration dilution obtained above and 33.3 mass% HDPE2, it put into the said twin screw extruder, and provided for 2nd melt-kneading. The kneading was carried out by adjusting the feeder so that the discharge amount was 1 to 2 kg/Hr at temperature = 210°C and screw rotation speed = 200 rotations to obtain pellets of the first intermediate of the polyethylene resin composition.

After mixing 81.1 mass% of the polyethylene resin composition 1st intermediate|middle obtained above and HDPE1 of 18.9 mass %, it put into the said twin screw extruder, and provided for 3rd melt-kneading. The kneading was carried out by adjusting the feeder so that the discharge amount was about 1 to 2 kg/Hr at temperature = 210°C and screw rotation speed = 200 rotations, thereby obtaining a second intermediate of a polyethylene resin composition.

After mixing 40 mass% of the polyethylene type resin composition 2nd intermediate|mold obtained above and 60 mass% of LLDPE1, it put into the said twin screw extruder, and it provided for 4th melt-kneading. The kneading was carried out by adjusting the feeder so that the discharge amount was about 3 to 5 kg/Hr at a temperature of 210°C and a screw rotation speed of 200 rotations to obtain pellets of a polyethylene resin composition.

This pellet was supplied to an extruder of a single-layer inflation molding machine, and a molten resin extruded 2.5 Kg/Hr from a 200° C. die was inflation-molded to obtain a polyolefin resin film having a thickness of 0.15 mm and a width of 30 cm.

About a part of the obtained polyethylene resin, the density was measured. Further, for the polyethylene-based film obtained by inflation molding, the dynamic friction coefficient D, the static friction coefficient S, the tensile modulus of elasticity, the measurement of the internal haze, and the friction failure test were performed by the above-described methods.

The composition of the obtained polyethylene resin composition and film, and the measurement result of each physical property are shown in Table 1.

[Example 2]

After mixing 55.5 mass% of UHMWPE1 and 44.5 mass% of LLDPE2, they were melt-kneaded with a Toshiba Machinery Co., Ltd. TEM-18ss twin screw extruder (L/D = 50). The kneading was carried out by adjusting the feeder so that the discharge amount was about 1 to 2 kg/Hr at temperature = 215°C and screw rotation speed = 200 rotations to obtain a polyethylene-based resin composition high-concentration dilution.

After mixing 66.7 mass% of the polyethylene resin composition high-concentration dilution obtained above and 33.3 mass% of LLDPE3, it put into the said twin screw extruder, and provided for 2nd melt-kneading. The kneading was carried out by adjusting the feeder so that the discharge amount was 1 to 2 kg/Hr at temperature = 210°C and screw rotation speed = 200 rotations to obtain a polyethylene resin composition first intermediate.

After mixing 81.1 mass% of the polyethylene resin composition 1st intermediate|middle obtained above and LLDPE2 of 18.9 mass %, it put into the said twin screw extruder, and provided for 3rd melt-kneading. The kneading was carried out by adjusting the feeder so that the discharge amount was about 1 to 2 kg/Hr at temperature = 210°C and screw rotation speed = 200 rotations to obtain a second polyethylene-based resin intermediate.

After mixing 40 mass% of the polyethylene type resin composition 2nd intermediate|mold obtained above and 60 mass% of LLDPE1, it put into the said twin screw extruder, and it provided for 4th melt-kneading. The kneading was carried out by adjusting the feeder so that the discharge amount was about 3 to 5 kg/Hr at a temperature of 210°C and a screw rotation speed of 200 rotations to obtain pellets of a polyethylene resin composition.

This pellet was supplied to an extruder of a single-layer inflation molding machine, and a molten resin extruded 2.5 Kg/Hr from a 200° C. die was inflation-molded to obtain a polyolefin resin film having a thickness of 0.15 mm and a width of 30 cm.

The composition of the obtained polyethylene resin composition and film, and the measurement result of each physical property are shown in Table 1.

[Example 3]

After mixing 50 mass% HDPE1 and 50 mass% HDPE2, it melt-kneaded with the Toshiba Machinery Co., Ltd. TEM-18ss twin screw extruder (L/D=50). The kneading was carried out by adjusting the feeder so that the discharge amount was about 3 to 5 kg/Hr at temperature = 205°C and screw rotation speed = 200 rotations to obtain a polyethylene-based resin composition intermediate.

After mixing 36 mass% of the polyethylene resin composition intermediate|middle obtained above and 64 mass% LLDPE1, it put into the said twin screw extruder, and it provided for 2nd melt-kneading. The kneading was carried out by adjusting the feeder so that the discharge amount was about 3 to 5 kg/Hr at a temperature of 210°C and a screw rotation speed of 200 rotations to obtain pellets of a polyethylene resin composition.

This pellet was supplied to an extruder of a single-layer inflation molding machine, and a molten resin extruded 2.5 Kg/Hr from a 200° C. die was inflation-molded to obtain a polyolefin resin film having a thickness of 0.15 mm and a width of 30 cm.

The composition of the obtained polyethylene resin composition and film, and the measurement result of each physical property are shown in Table 1.

[Example 4]

After mixing 50 mass% of the polyethylene resin composition 2nd intermediate|mold and 50 mass% LLDPE1 obtained by 3rd kneading of Example 1, it put into the said twin screw extruder, and it provided for 4th melt-kneading. The kneading was carried out by adjusting the feeder so that the discharge amount was about 1 to 2 kg/Hr at temperature = 210°C and screw rotation speed = 200 rotations to obtain pellets of a polyethylene-based resin composition.

This pellet was supplied to an extruder of a single-layer inflation molding machine, and a molten resin extruded 2.5 Kg/Hr from a 200° C. die was inflation-molded to obtain a polyolefin resin film having a thickness of 0.15 mm and a width of 30 cm.

The composition of the obtained polyethylene resin composition and film, and the measurement result of each physical property are shown in Table 1.

[Example 5]

After mixing 80 mass% of the polyethylene resin composition 2nd intermediate|mold and 20 mass% LLDPE1 obtained by 3rd kneading of Example 1, it put into the said twin screw extruder, and it provided for 4th melt-kneading. The kneading was carried out by adjusting the feeder so that the discharge amount was about 1 to 2 kg/Hr at a temperature of 210°C and a screw rotation speed of 200 rotations to obtain pellets of a polyethylene resin composition.

This pellet was supplied to an extruder of a single-layer inflation molding machine, and a molten resin extruded 1.5 Kg/Hr from a 200° C. die was inflation-molded to obtain a polyolefin resin film having a thickness of 0.15 mm and a width of 30 cm.

The composition of the obtained polyethylene resin composition and film, and the measurement result of each physical property are shown in Table 1.

[Example 6]

After mixing 80 mass% of the polyethylene resin composition 2nd intermediate|mold and 20 mass% LLDPE1 obtained by 3rd kneading of Example 2, it put into the said twin screw extruder, and it provided for 4th melt-kneading. The kneading was carried out by adjusting the feeder so that the discharge amount was about 1 to 2 kg/Hr at a temperature of 210°C and a screw rotation speed of 200 rotations to obtain pellets of a polyethylene resin composition.

This pellet was supplied to an extruder of a single-layer inflation molding machine, and a molten resin extruded 1.5 Kg/Hr from a 200° C. die was inflation-molded to obtain a polyolefin resin film having a thickness of 0.15 mm and a width of 30 cm.

The composition of the obtained polyethylene resin composition and film, and the measurement result of each physical property are shown in Table 1.

[Example 7]

After mixing 55.5 mass% of UHMWPE1 and 44.5 mass% of HDPE1, they were melt-kneaded with a Toshiba Machinery Co., Ltd. TEM-18ss twin screw extruder (L/D = 50). The kneading was carried out by adjusting the feeder so that the discharge amount was about 1 to 2 kg/Hr at temperature = 215°C and screw rotation speed = 200 rotations to obtain a polyethylene-based resin composition high-concentration dilution.

After mixing 66.4 mass% of the polyethylene resin composition high-concentration dilution obtained above, HDPE2 of 33.1 mass %, and processing aid 1 of 0.5 mass %, it put into the said twin screw extruder, and provided for 2nd melt-kneading. Kneading was carried out by adjusting the feeder so that the discharge amount was 1 to 2 kg/Hr at temperature = 180°C and screw rotation speed = 200 rotations, thereby obtaining pellets of the first intermediate of the polyethylene resin composition.

After mixing 81.1 mass% of the polyethylene resin composition 1st intermediate|middle obtained above and HDPE1 of 18.9 mass %, it put into the said twin screw extruder, and provided for 3rd melt-kneading. The kneading was carried out by adjusting the feeder so that the discharge amount was about 1 to 2 kg/Hr at temperature = 210°C and screw rotation speed = 200 rotations, thereby obtaining a second intermediate of a polyethylene resin composition.

After mixing 40.1 mass% of the polyethylene resin composition 2nd intermediate|middle obtained above and 59.9 mass% of LLDPE1, it put into the said twin screw extruder, and it provided for 4th melt-kneading. The kneading was carried out by adjusting the feeder so that the discharge amount was about 3 to 5 kg/Hr at a temperature of 210°C and a screw rotation speed of 200 rotations to obtain pellets of a polyethylene resin composition.

This pellet was supplied to an extruder of a single-layer inflation molding machine, and a molten resin extruded 2.5 Kg/Hr from a 200° C. die was inflation-molded to obtain a polyolefin resin film having a thickness of 0.15 mm and a width of 30 cm.

The composition of the obtained polyethylene resin composition and film, and the measurement result of each physical property are shown in Table 1.

[Comparative Examples 1 to 5]

Except having changed the composition of the polyethylene component (A) and the polyethylene component (B) as shown in Table 1, it produced similarly to an Example, and each physical property was measured. Table 1 shows the results.

The polyethylene-based film of the present invention can be widely used as an agricultural film for use in plastic houses and multi-films, a film for packaging such as food, a film for covering such as electric wires, and the like.

Claims (9)

It has a density of 0.920 to 0.950 g/cm 3, and both the dynamic friction coefficient D and the static friction coefficient S are 0.30 or less, and the ratio D/S of the dynamic friction coefficient D to the static friction coefficient S is 1.0 or less. As a polyethylene resin composition,
A polyethylene-based resin composition containing a polyethylene component (A) and a polyethylene component (B) showing different tensile modulus. delete The method of claim 1,
The polyethylene component (A) contains a linear low-density polyethylene, and the polyethylene component (B) contains an ultra-high molecular weight polyethylene. The method of claim 3,
A polyethylene-based resin composition containing 50 to 99.9 mass% of the polyethylene component (A) and 0.1 to 50 mass% of the polyethylene component (B) relative to 100 mass% of the polyethylene resin composition. The method of claim 1,
A polyethylene resin composition having a tensile modulus of 0.35 GPa or more measured in accordance with JIS K7127. The method of claim 1,
A polyethylene resin composition having an internal haze of 45 or less in a 150 µm-thick film measured according to JIS K7136. A polyethylene-based film comprising a surface layer made of the polyethylene-based resin composition according to any one of claims 1 and 3 to 6. The method of claim 7,
A polyethylene-based film further comprising an adhesive layer laminated on the surface layer. The method of claim 7,
Agricultural use, polyethylene film.