Polyethylene resin composition, film comprising the composition, laminated film and packaging film comprising the film

Abstract

To provide a polyethylene resin composition excellent in transparency, rigidity, blocking resistance, and molding processability.SOLUTION: The polyethylene-based resin composition contains a polyethylene-based resin satisfying specific conditions in addition to the following requirements (1) to (3). (1) MFR (190 °C, load 2. 16kg) is 1.0 to 10. 0g / 10 min. (2) The densities are 0. 910g / cm3 or more and less than 0. 930g / cm3. (3) The ratio of the melt flow rate (HLMFR) measured at a temperature of 190 °C. under a load of 21 6Kg to the melt flow rate (MFR) measured at a temperature of 190 °C. under a load of 2 16kg is 30 or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a polyethylene resin composition that has excellent molding processability and an excellent balance between mechanical properties and rigidity, as well as to a film made of the composition, a laminated film containing the film, and a packaging film containing the film.

[0002] In recent years, plastic films, sheets, injection molded products, pipes, extrusion molded products, blow molded products, etc. have come into widespread use in various industrial fields. Polyethylene films in particular are widely used for packaging purposes due to their low cost, light weight, moldability, rigidity, impact strength, transparency, chemical resistance, and recyclability.

[0003] In the production of polyethylene films, polyethylene resins are generally molded in a molten state. However, in the case of a single ethylene polymer, its melting properties are often insufficient, for example, in terms of fluidity or elongational viscosity, making it difficult to ensure sufficient moldability, and the resulting film often has insufficient solid properties such as transparency, rigidity, and blocking.

[0004] To address these issues, efforts have been made to improve melting characteristics and solid physical properties by blending high-pressure low-density polyethylene (HPLD), which has excellent moldability, or blending ethylene polymers with different molecular weights and densities (see Patent Documents 1 to 3). However, although these blends (ethylene resin compositions) provide moldability, they have the problem of lowering impact strength due to the blending of HPLD.

[0005] Furthermore, in light of the need to reduce the amount of raw resin used in recent container recycling trials and resource conservation efforts, there is an increasing demand for thinner molded articles. However, this requires improvements in both impact strength and rigidity (elastic modulus). A well-known method for improving impact strength is to reduce the density of ethylene polymers, but this is undesirable because it also reduces rigidity (softening). To achieve thinner walls, attempts have been made to combine two specific ethylene-α-olefin copolymers with different densities, or to use ternary blend compositions that incorporate specific HPLD to improve moldability and transparency (see Patent Document 4). While this method produces polyethylene resin compositions with a better balance of impact strength and rigidity and superior transparency than conventional methods, the reduction in impact strength associated with HPLD blends is unavoidable. Furthermore, blends of three ethylene polymers are considered to be less economical than conventional methods for providing a stable supply of consistent quality at an industrial level.

[0006] On the other hand, as a method for improving molding processability, attempts have been made to introduce long chain branched structures into ethylene polymers to increase melt viscosity. However, due to insufficient optimization of the long chain branched structures, a decrease in strength is still unavoidable, and the level of improvement is still insufficient (see Patent Documents 5 to 8).

[0007] Under these circumstances, there has been a demand for the development of a polyethylene resin composition which overcomes the problems associated with conventional ethylene-based resin compositions, has excellent moldability, and is capable of producing molded articles which are excellent in transparency, rigidity, and blocking resistance. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 7-149962 [Patent Document 2] Japanese Patent Application Publication No. 9-31260 [Patent Document 3] Japanese Patent Application Laid-Open No. 2006-312753 [Patent Document 4] Japanese Patent Application Laid-Open No. 2010-31270 [Patent Document 5] WO 97 / 10295 [Patent Document 6] Japanese Patent Application Laid-Open No. 2006-63325 [Patent Document 7] Japanese Patent Application Laid-Open No. 2006-124567 [Patent Document 8] Japanese Patent Application Laid-Open No. 2007-197722 Summary of the Invention [Problem to be solved by the invention]

[0009] In view of the above-mentioned problems of the prior art, an object of the present invention is to provide a polyethylene resin composition which is excellent in transparency, rigidity, blocking resistance, and moldability. [Means for solving the problem]

[0010] As a result of intensive research to solve the above problems, the present inventors discovered that it is possible to achieve a balance between impact resistance and rigidity by using a resin having a specific molecular weight distribution and melt tension, and thus completed the present invention.

[0011] That is, according to the present invention [1], there is provided a polyethylene resin composition containing a polyethylene resin that satisfies the following requirements (1) to (6). (1) The melt flow rate (MFR: 190°C, load 2.16 kg) is 1.0 to 10.0 g / 10 min. (2) Density is 0.910 g / cm 3 More than 0.930g / cm 3 is less than. (3) The ratio of the melt flow rate (HLMFR) measured at a temperature of 190°C and a load of 21.6 kg to the melt flow rate (MFR) measured at a temperature of 190°C and a load of 2.16 kg is 30 or less. (4) In a log-log plot of the extensional viscosity η(t) (unit: Pa·sec) measured at a temperature of 170°C and an extensional strain rate of 2 (unit: 1 / sec) versus the extensional time t (unit: sec), the strain hardening ratio (λmax(2.0)), defined as η;Max(t1) / η;Linear(t1), is 4.0–10.0, where η;Max(t1) is the maximum extensional viscosity after strain hardening and η;Linear(t) is the approximate straight line of the extensional viscosity before hardening. (5) In the plot of storage modulus (unit: MPa) measured at a temperature of 170°C versus angular frequency (unit: rad / s), the storage modulus (E 0.1 ) and storage modulus at an angular frequency of 100 rad / s (E 100 ) The slope of the line passing through these two points is 1100 or less. (6) The molecular weight distribution (Mw / Mn), which is the ratio of the number average molecular weight (Mn) to the weight average molecular weight (Mw) determined by GPC (Gel Permeation Chromatography), is 2.5 to 5.0.

[0012] Furthermore, according to the present invention [2], there is provided a polyethylene resin composition according to the present invention [1], in which the polyethylene resin further satisfies the requirements (7) and (8). Furthermore, according to the present invention [3], there is provided a polyethylene resin composition according to the present invention [1] or [2], wherein the polyethylene resin further satisfies the requirement (9). According to the present invention [4], there is provided a film obtained by using the polyethylene resin composition according to any one of the present inventions [1] to [3]. Furthermore, according to the present invention [5], a film can be obtained which is characterized in that the content of the antiblocking agent in the film according to the present invention [4] is 2000 ppm or less and the content of the slip agent is 300 ppm or less. Furthermore, according to the present invention [6], a multilayer film having at least one layer made of the film according to the present invention [4] or [5] can be obtained. Furthermore, according to the present invention [7], there is provided a packaging material having at least one layer of the film according to any one of the present inventions [4] to [6]. [Effects of the Invention]

[0013] A film and a multilayer film obtained using the polyethylene resin composition of the present invention have an excellent balance between impact resistance (dirt drop impact), tensile modulus and tear strength, and also have excellent transparency and moldability, and are therefore particularly suitable for use as sealant films for food packaging, standing pouches, BIBs, inner bags, agricultural films, etc. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a plot diagram of the extensional viscosity when an inflection point of the extensional viscosity is observed (a typical example of the ethylene polymer (A-1) in the Examples). [Figure 2] FIG. 2 is a plot diagram of the extensional viscosity when no inflection point of the extensional viscosity is observed (a typical example of the ethylene polymer (A-3) in the Examples). DETAILED DESCRIPTION OF THE INVENTION

[0015] The present invention relates to a polyethylene resin composition having excellent moldability, a film obtained using the same, and a multilayer film and packaging film each containing the same. The present invention will be described below item by item.

[0016] 1. Polyethylene resin composition The polyethylene resin composition in the present invention is a resin composition used as a raw material for a stretched polyethylene substrate film or a polyethylene sealant film, and means either a polyethylene resin alone or a mixture of such polyethylene resins, to which necessary additives may be added. Polymerization catalyst and polymerization method for polyethylene resin composition Polyethylene resins for constituting polyethylene resin compositions are produced using either petroleum-derived ethylene or biomass-derived ethylene, or both, as raw materials, with a conventionally known catalyst, such as a metal catalyst such as a Ziegler-Natta catalyst, a Phillips catalyst, or a metallocene catalyst. Generally, these catalysts are in the form of a complex composed of an organometallic compound supported on a carrier such as silica or a Mg compound. Polymerization methods include high-pressure, solution, slurry, and gas-phase polymerization. High-pressure polymerization uses a radical-generating source such as oxygen or peroxide, or a catalyst composed of a metal complex, as an initiator. Ethylene, comonomer, and initiator are introduced into a reactor under high-temperature and high-pressure conditions. Depending on the reactor's shape, this can be further divided into tubular and autoclave processes. Solution polymerization is carried out in a hydrocarbon solvent at a temperature above the polymer's melting point. Slurry polymerization uses a hydrocarbon solvent, such as hexane or isobutane, and the resulting polyethylene exists in the solvent as a slurry. Depending on the reactor's shape, this can be broadly divided into autoclave and loop-pipe processes. Gas-phase polymerization involves feeding ethylene, an α-olefin comonomer, and hydrogen as a chain transfer agent into the bottom of a vertical reactor, all in gaseous form, followed by the addition of a polymerization catalyst (from Polyethylene Technology Reader, edited by Kazuo Matsuura and Hisataka Mikami).

[0017] Polyethylene resins obtained by these production methods have a wide range of combinations of density, melt flow rate (MFR), and other resin physical properties to meet various conventionally known applications, but among them, the polyethylene resin composition of the present invention contains a polyethylene resin that satisfies the requirements (1) to (6) described below. Hereinafter, a polyethylene resin that satisfies the requirements (1) to (6) will also be referred to as the "polyethylene resin of the present invention," and a resin composition containing the polyethylene resin of the present invention will also be referred to as the "polyethylene resin composition of the present invention."

[0018] Requirement (1): MFR The melt flow rate (MFR) of the polyethylene resin of the present invention is 1.0 g / 10 min or more and 10 g / 10 min or less, preferably 1.0 g / 10 min or more and 5.0 g / 10 min or less, and more preferably 1.5 g / 10 min or more and 5.0 g / 10 min or less. When the MFR is within this range, the polyethylene resin composition has excellent moldability and a good balance between impact strength and rigidity. On the other hand, an MFR of less than 1.0 g / 10 min may be undesirable in terms of moldability, etc., while an MFR of more than 10 g / 10 min is undesirable because it is difficult to fully achieve the effects of improving impact strength and rigidity. In the present invention, the MFR of the polyethylene resin refers to the value measured at 190°C and a load of 21.18 N (2.16 kg) in accordance with JIS K7210, "Testing method for melt mass-flow rate (MFR) and melt volume-flow rate (MVR) of plastics - thermoplastic plastics."

[0019] Requirement (2): Density The density of the polyethylene resin of the present invention is 0.910 to 0.930 g / cm 3 and preferably 0.910 g / cm 3 More than 0.928g / cm 3 less than 0.915 to 0.925 g / cm 3 is. When the density is within this range, the polyethylene resin composition to be modified has an excellent effect of improving the balance between impact strength and rigidity. 3 If the density is less than 0.930 g / cm3, it may be undesirable in terms of rigidity. 3 If it is larger, the effect of improving the impact strength etc. will be insufficient, which is not preferable. In the present invention, the density of the polyethylene resin refers to a value measured by the following method.

[0020] The pellets were hot-pressed to prepare a 2 mm thick pressed sheet. The sheet was then placed in a 1000 ml beaker, filled with distilled water, covered with a watch glass, and heated in a mantle heater. After boiling for 60 minutes, the beaker was placed on a wooden stand and allowed to cool. The amount of boiling water after 60 minutes was 500 ml, and the time required for the water to cool to room temperature was adjusted to at least 60 minutes. The test sheet was immersed in the water at approximately the center, avoiding contact with the beaker or the water surface. The sheet was annealed at 23°C and 50% humidity for 16 to 24 hours. It was then punched out into 2 mm squares and measured at a test temperature of 23°C in accordance with JIS K7112, "Method for measuring density and specific gravity of plastics - non-foamed plastics."

[0021] Requirement (3): HLMFR / MFR Furthermore, it is important to select a polyethylene resin of the present invention having a ratio of HLMFR to MFR (HLMFR / MFR) of 30 or less, preferably 28 or less, and more preferably 26 or less. HLMFR / MFR is closely correlated with molecular weight distribution; when HLMFR / MFR is large, the molecular weight distribution becomes broad, and when HLMFR / MFR is small, the molecular weight distribution becomes narrow. If HLMFR / MFR exceeds 30, the balance between impact strength and rigidity may be undesirable.

[0022] Requirement (4): Strain hardening degree (λmax(2.0)) Furthermore, the polyethylene resin of the present invention has a maximum elongational viscosity after strain hardening of η(t) (unit: Pa·sec) measured at a temperature of 170°C and an elongational strain rate of 2 (unit: 1 / sec) in a double logarithmic plot of the elongational viscosity η(t) (unit: Pa·sec) versus the elongational time t (unit: sec). Max (t1), the approximate line of the elongational viscosity before curing is η Linear (t1), then η Max (t1) / η Linear The strain hardening (λmax(2.0)) defined by (t1) is 3.0 or more. This λmax(2.0) value indicates the degree of development of long chain branches introduced into the polyethylene resin. If λmax(2.0) is less than 3.0, the flowability and melt tension of the polyethylene resin composition and molded articles produced using the composition will be insufficient, resulting in poor molding processability.

[0023] In general, polyethylene is processed into industrial products by a molding method that involves passing through a molten state during film formation. In this process, the elongational flow properties, typified by the above-mentioned elongational viscosity and strain hardening, have a significant impact on the ease of formability. Specifically, polyethylene with a narrow molecular weight distribution and no long-chain branching has poor moldability due to low melt strength, while polyethylene with ultra-high molecular weight components or long-chain branching exhibits strain hardening during melt elongation, i.e., a rapid increase in elongational viscosity at high strains. Polyethylenes that exhibit this characteristic significantly exhibit excellent moldability. Polyethylene resins with such elongational flow properties have the advantages of preventing thickness variations and breakage during film molding and enabling high-speed molding, thereby improving the strength of molded products. However, excessive elongational flow properties can also cause problems, such as reduced impact strength of molded products due to strength anisotropy, presumably caused by molecular orientation during molding, and reduced transparency due to reduced surface smoothness, presumably caused by excessive melt elasticity. As described above, the inventors have conducted extensive studies on polyethylene resin compositions to improve the molding processability and overcome the disadvantages in the mechanical properties of molded articles that are caused by the extensional flow properties of polyethylene by modifying the long-chain branching structure, which is the main controlling factor in the extensional viscosity properties. As a result, it has been found that the use of a resin composition containing a polyethylene resin that satisfies the above-mentioned requirement (4) is excellent in contributing to the improvement of mechanical properties, particularly rigidity.

[0024] Regarding the method for measuring the strain hardening, any method can in principle obtain the same value as long as it can measure the uniaxial extensional viscosity, and details of the measurement method and measuring equipment are described in, for example, the publicly known document: Polymer 42 (2001) 8663. In measuring the polyethylene resin of the present invention, the following measurement methods and instruments are preferable.

[0025] Measurement method: Device: Anton Paar MCR302 Fixture: Anton Paar Sentmanat Extension Rheometer ·Measurement temperature: 170℃ Strain rate: 2 / sec Preparation of test specimen: A 1mm thick press sheet was prepared by pressing at a temperature of 180°C, and then cut to an appropriate size for measurement.

[0026] Calculation method: The extensional viscosity at 170°C and a strain rate of 2 / sec is plotted on a double logarithmic graph with time t (sec) on the horizontal axis and extensional viscosity η (Pa·sec) on the vertical axis. On the double logarithmic graph, the maximum extensional viscosity after strain hardening until the strain amount reaches 4.0 is defined as η Max (t1) (t1 is the time when the maximum elongational viscosity is shown), and the approximate line of the elongational viscosity before strain hardening is η Linear (t), then η Max (t1) / η Linear The value calculated as (t1) is the strain hardening (λ max The presence or absence of strain hardening is determined by whether or not there is an inflection point where the extensional viscosity changes from an upwardly convex curve to a downwardly convex curve with the passage of time. Figures 1 and 2 are typical plots of extensional viscosity. Figure 1 shows a case where an inflection point of extensional viscosity is observed, and η Max (t1), η Linear Figure 2 shows the case where the inflection point of the extensional viscosity is not observed.

[0027] Requirement (5): Storage modulus (E 0.1 ) Furthermore, in a plot of storage modulus (unit: MPa) vs. angular frequency (unit: rad / s) measured at a temperature of 170°C, the polyethylene resin of the present invention has a storage modulus (E 0.1) and storage modulus at an angular frequency of 100 rad / s (E 100 ) is characterized in that the slope of the line passing through these two points is 1100 or less.

[0028] The storage modulus corresponds to the elastic response of a sample when stress is measured by applying a sine wave of a specified frequency to the sample. The stress is separated into a component in phase with the applied strain, with a phase difference δ, and a component 90 degrees out of phase with the strain. The storage modulus E' is calculated from the maximum value of these components. These definitions are found, for example, in "Lectures on Rheology" (edited by the Japanese Society of Rheology, Polymer Publishing Association, 1992, pp. 36-37).

[0029] The storage modulus (E 0.1 ) and storage modulus at an angular frequency of 100 rad / s (E 100 The gradient of the line passing through these two points is 1100 or less, preferably 1050 or less, and more preferably 1000 or less. The storage modulus is correlated with the relaxation time of the molecule. If the molecular weight is small or there is no long chain branching, the relaxation time of the molecule will be short, and the storage modulus on the low frequency side will be small. On the other hand, if the molecular weight is large or there is long chain branching, the relaxation time of the molecule will be long, and the storage modulus on the low frequency side will be large. If the material does not have a component with a long relaxation time, the melt strength is low, and the moldability is poor. 0.1 and E 100 The gradient of the line passing through these two points becomes larger. When a component with a long relaxation time is included, the moldability is excellent, and E 0.1 and E 100 The slope of the line passing through these two points becomes smaller. On the other hand, if there are too many components with long relaxation times, the molded body may break. Intensive studies were conducted on polyethylene resin compositions to solve the problem by adjusting the molecular weight and the long chain branching structure, which are the main controlling factors for the storage modulus. As a result, it was found that the use of the resin composition contributes to an excellent improvement in moldability, as described above.

[0030] Measurement method: Equipment: Anton Paar MCR302 Fixture: Anton Paar 25mm parallel plate ·Measurement temperature: 170℃ Measurement mode: Frequency dispersion Frequency: 100~0.1rad / s Distortion: Set to 5-10% (automatic adjustment) Preparation of test specimen: A 1mm thick press sheet was prepared by pressing at a temperature of 180°C, and then cut to an appropriate size for measurement.

[0031] Requirement (6): Molecular weight distribution (Mw / Mn) Furthermore, the ratio Mw / Mn (hereinafter also referred to as Q value) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the polyethylene resin is 2.5 to 5.0. If the Q value is less than 2.5, the molding processability of the polyethylene resin composition may deteriorate. If the Q value exceeds 5.0, the balance between impact resistance and rigidity is impaired. In terms of the balance between impact resistance and rigidity, the upper limit of the Q value is preferably 4.5 or less, more preferably 4.0 or less. The lower limit of the Q value is preferably 2.7 or more, more preferably 2.9 or more.

[0032] Here, Mw / Mn refers to a value measured under the following conditions (hereinafter sometimes referred to as "method for measuring molecular weight distribution"): Mw / Mn is defined as the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) measured by gel permeation chromatography (GPC).

[0033] Apparatus: Waters GPC 150C type detector: MIRAN 1A infrared spectrophotometer (measurement wavelength: 3.42 μm) Column: Showa Denko AD806M / S (3 columns) [The column was calibrated using Tosoh monodisperse polystyrene (A500, A2500, F1, F2, F4, F10, F20, F40, and F288, each 0.5 mg / ml solution). The logarithm of the elution volume and molecular weight was approximated by a quadratic equation. The molecular weight of the sample was converted to polyethylene using the viscosity equation for polystyrene and polyethylene. The viscosity equation for polyethylene is α = 0.723, log K = -3.967, while that for polyethylene is α = -0.723, log K = -3.407.] Measurement temperature: 140℃ Injection amount: 0.2ml Concentration: 20mg / 10ml Solvent: orthodichlorobenzene Flow rate: 1.0ml / min

[0034] In one preferred embodiment of the polyethylene resin composition of the present invention, the polyethylene resin of the present invention further satisfies the following requirements (7) and (8).

[0035] Requirement (7) The ratio (HLMFR / MFR) of the melt flow rate at a temperature of 190°C and a load of 21.6 kg (HLMFR) to the melt flow rate (MFR) measured at a temperature of 190°C and a load of 2.16 kg is 17-25, preferably 18-24. As explained in requirement (3), HLMFR / MFR is a property that is strongly correlated with molecular weight distribution. Requirement (7) specifies a preferred range for HLMFR / MFR, with a HLMFR / MFR of 25 or less tending to provide a better balance between impact strength and rigidity. On the other hand, a HLMFR / MFR of less than 17 may result in poor molding processability.

[0036] Requirement (8) In the plot of storage modulus (unit: MPa) measured at a temperature of 170°C versus angular frequency (unit: rad / s), the storage modulus (E 0.1 ) and storage modulus at an angular frequency of 100 rad / s (E 100The gradient of the line passing through these two points is 800 to 1000, preferably 850 to 1000. Requirement (8) is E 0.1 and E 100 If the slope of the line is 1000 or less, the molding processability tends to be better. On the other hand, if the slope of the line is less than 800, the balance between impact strength and rigidity may be undesirable.

[0037] In one preferred embodiment of the polyethylene resin composition of the present invention, the polyethylene resin of the present invention further satisfies the following requirement (9).

[0038] Requirement (9) In a log-log plot of the extensional viscosity η(t) (unit: Pa·sec) measured at a temperature of 170°C and an extensional strain rate of 2 (unit: 1 / sec) versus the extension time t (unit: sec), the maximum extensional viscosity after strain hardening was defined as η Max (t1), the approximate line of the elongational viscosity before curing is η Linear (t1), then η Max (t1) / η Linear The strain hardening rate [λ max (2.0)] is 4.0 to 15.0. When λmax(2.0) is 4.0 or more, the polyethylene resin composition and the molded article produced therefrom have sufficient fluidity and melt tension, resulting in better molding processability. When λmax(2.0) is 15.0 or less, the polyethylene resin composition and the molded article can be prevented from decreasing in impact strength while maintaining good fluidity and melt tension. λmax (2.0) is preferably 4.0 to 13.0, more preferably 5.0 to 13.0, and even more preferably 6.0 to 12.0.

[0039] The polyethylene resin of the present invention is not particularly limited as long as it satisfies the above requirements (1) to (6) (preferably, further satisfies requirements (7) and (8), and more preferably, further satisfies requirement (9)). Usable polyethylene resins include ultra-low density polyethylene (ULDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), medium density polyethylene (MDPE), and high density polyethylene (HDPE). The polyethylene resin of the present invention also includes ethylene-α-olefin copolymers, and the α-olefin that can be used here is propylene, 1-butene, 1-hexene, 1-octene, 4-methyl-1-pentene, etc.

[0040] 2.Polyethylene film Polyethylene resin composition used A film composed of the polyethylene resin composition of the present invention contains at least one layer composed of the polyethylene resin composition of the present invention. That is, one embodiment of the present invention is a film obtained using the polyethylene resin composition of the present invention (hereinafter also referred to as "film of the present invention"). The film of the present invention is characterized in that it can be sealed by fusion bonding of the layer made of the polyethylene resin composition of the present invention. The polyethylene resin composition that can be used is not particularly limited as long as it contains a polyethylene resin that satisfies the above requirements (1) to (6) (preferably, further satisfies requirements (7) and (8), and more preferably, further satisfies requirement (9)). Examples of the polyethylene resin include ultra-low density polyethylene (ULDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), medium density polyethylene (MDPE), and high density polyethylene (HDPE).

[0041] Additives The polyethylene resin composition used in the film of the present invention may contain additives generally used in resin compositions, such as antioxidants, heat stabilizers, neutralizing agents, antiblocking agents, tackifiers, antistatic agents, slip agents, nucleating agents, foaming agents, crosslinking agents, biomass resources, and biodegradation accelerators, within limits that do not impair the functionality of the film. Furthermore, in the film of the present invention, the content of the antiblocking agent is preferably 4000 ppm or less and the content of the slip agent is preferably 600 ppm or less, and more preferably 2000 ppm or less and the content of the slip agent is 300 ppm or less.

[0042] The manufacturing method and manufacturing conditions of the film of the present invention The film of the present invention can be produced by known techniques, such as inflation molding, T-die molding, and calender molding, with inflation molding and T-die molding being preferred.

[0043] Film structure of the present invention The film of the present invention may have a single-layer structure or a multi-layer structure. In the case of a single-layer structure, the polyethylene resin composition of the present invention may be used alone, or the polyethylene resin composition of the present invention may be used in combination with other polyethylene resin compositions. In the case of a multi-layer structure, it is preferably formed by co-extrusion molding using the above-mentioned known techniques, and it is also preferable that the film have at least three layers.

[0044] 4.Laminate Multilayer film The film of the present invention may be a film formed by laminating, in addition to a film formed from the polyethylene resin composition of the present invention, a layer formed from at least one or more films formed from polyethylene resin compositions and obtained by inflation molding or T-die molding. That is, one embodiment of the present invention is a multilayer film having at least one layer made of the film of the present invention (hereinafter also referred to as "the multilayer film of the present invention"). Resins that can be used in the polyethylene resin composition used in layers other than the film composed of the polyethylene resin composition of the present invention include high-density polyethylene (HDPE), medium-density polyethylene (MDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and ultra-low-density polyethylene (ULDPE). Furthermore, lamination may be performed by further stretching a co-extruded film obtained by co-extrusion molding, or by bonding films together using an adhesive.

[0045] ·glue An adhesive can be used to laminate the multilayer film. The adhesive used contains at least one resin composition, but is not particularly limited. Examples of adhesives that can be used include epoxy, acrylic, and urethane types. Furthermore, the adhesive containing any of the above resin compositions is not particularly limited, but can be one-component, two-component, or hot melt type, as needed.

[0046] 5. Packaging film A multilayer film having at least one layer made of the polyethylene resin composition of the present invention can be particularly suitably used as a packaging material. That is, another aspect of the present invention is a packaging film having at least one layer of the film of the present invention (hereinafter also referred to as the "packaging film of the present invention"). The shape of the packaging material is not particularly limited and may be a packaging bag or a stand-up pouch, in which only the body, only the bottom, or both the body and bottom may be formed from the resin laminate.

[0047] ·Packaging bag The bag-shaped packaging material can be produced by folding the multilayer film in half, overlapping it so that the heat seal layer of the multilayer film is on the inside, and heat sealing the ends. Alternatively, a bag-shaped packaging material can be produced by overlapping two laminates with their heat-sealable layers facing each other, and then heat-sealing the ends of the laminate.

[0048] ·Applications The multilayer film of the present invention satisfies the melt tension required for molding and has an excellent balance between impact resistance and rigidity, and is therefore suitable for use as a material for food packaging sealant films, standing pouches, BIBs, inner bags, agricultural films, etc. [Example]

[0049] The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. The evaluation methods, analytical methods, materials, etc. used in the examples are as follows.

[0050] 1. Physical property measurement method (1) MFR Measurement was carried out in accordance with JIS K6922-2 at 190°C under a load of 2.16 kg. (2) Density Measurements were carried out in accordance with JIS K6922-1 and 2. (3)Molecular weight distribution The molecular weights (number average molecular weight (Mn), weight average molecular weight (Mw), and Z average molecular weight (Mz)) were measured by GPC, and the molecular weight distribution (ratio of weight average molecular weight (Mw) to number average molecular weight (Mn) (Mw / Mn)) was calculated. (4) Strain hardening degree [λ max (2.0)] The following equipment was used for the measurement by the method described in the present specification. Equipment: Anton Paar MCR302 Fixture: Anton Paar Sentmanat Extension Rheometer ·Measurement temperature: 170℃ Strain rate: 2 / sec Preparation of test specimen: A 0.5 mm thick press sheet was prepared by pressing at a temperature of 180°C, and then cut to an appropriate size for measurement. (5) Storage modulus (E 0.1 ) The following equipment was used for the measurement by the method described in the present specification. Equipment: Anton Paar MCR302 Fixture: Anton Paar 25mm parallel plate ·Measurement temperature: 170℃ Measurement mode: Temperature dependence Frequency: 1Hz Distortion: Set to 0.2% (automatic adjustment) Auto tension: Automatic static load (minimum load 25g) Heating rate: 5℃ / min Preparation of test specimen: A 1mm thick press sheet was prepared by pressing at a temperature of 180°C, and then cut to an appropriate size for measurement.

[0051] 2. Film evaluation method (1) Tensile modulus The tensile modulus was evaluated based on JIS K7127 using the following device. Equipment: Tensilon universal testing machine (manufactured by Orientec Co., Ltd.) ·Measurement environment: temperature 23℃, humidity 50% Test piece width: 10mm Pulling speed: 25mm / min Chuck distance: 100mm (2) Dirt drop impact (impact strength of a dirt drop) Measurement was carried out in accordance with JIS K 7124 1 A method. (3) Blocking test The blocking strength was evaluated in accordance with ASTM D1893 using the following device. Equipment: Tensilon tensile testing machine (manufactured by Orientec Co., Ltd.) ·Measurement environment: temperature 23℃, humidity 50% Test piece width: 20mm Contact area: 10cm 2 Test speed: 500mm / min Chuck distance: 100mm

[0052] 3.Resin used (1) Ethylene-α-olefin copolymer (A) A-1: Manufactured by Japan Polyethylene Co., Ltd., product name Harmolex, metallocene-based linear low-density polyethylene, grade name: NF465A, MFR = 2.0 g / 10 min, density = 0.919 g / cm 3 A-2: Manufactured by Japan Polyethylene Co., Ltd., trade name: Harmolex, metallocene-based linear low-density polyethylene, grade name: NF466A, MFR = 2.9 g / 10 min, density = 0.920 g / cm 3 A-3: Japan Polyethylene Co., Ltd., product name: Harmolex, metallocene-based linear low-density polyethylene, grade: NC564A, MFR = 3.5 g / 10 min, density = 0.918 g / cm 3 A-4: Japan Polyethylene Co., Ltd., product name: Harmolex, metallocene-based linear low-density polyethylene, grade: NF366A, MFR = 1.5 g / 10 min, density = 0.919 g / cm 3 (2) High-pressure radical low-density polyethylene (B) B-1: Novatec LD, manufactured by Japan Polyethylene Co., Ltd., low-density polyethylene, grade: LF240, MFR = 0.7 g / 10 min, density = 0.924 g / cm 3 B-2: Novatec LD, manufactured by Japan Polyethylene Co., Ltd., low-density polyethylene, grade LF441B, MFR = 2.0 g / 10 min, density = 0.924 g / cm 3 (3) Masterbatch C-1: Slip agent masterbatch manufactured by Japan Polyethylene Co., Ltd., Grade name: KMB05S, slip agent 5% by weight masterbatch C-2: Antiblocking agent masterbatch manufactured by Japan Polyethylene Corporation, Grade name: KMB16F, 16% by weight antiblocking agent masterbatch

[0053] 4. Single-layer blown film molding A single-layer inflation film was formed using the following molding equipment and conditions. Molding machine: Single layer inflation molding machine (manufactured by Placo Co., Ltd.) Extruder: 50mmφ Screw: LLDPE screw (compression ratio: 2.0, L / D: 24) Die diameter: 75mmφ Die lip width: 3mm or 1mm Processing temperature: C1 = 180°C, C2 to D2 = 190°C or C1 = 160°C, C2 to D2 = 170℃ Film thickness: 50 μm Extrusion rate: 20 kg / hr (thickness 50 μm) Take-up speed: 15 m / min (thickness 50 μm) BUR:2.0(236mm width)

[0054] [Table 1]

[0055] (Examples 1 to 3, Comparative Examples 1 to 4) Among the raw materials used above, the raw materials shown in Table 1 were used, and a film was obtained by inflation molding according to "4. Molding of monolayer inflation film." The inflation molding conditions are shown in Table 2. The obtained film was evaluated for dart drop impact strength (DDI), tensile modulus, and blocking test. The evaluation results are shown in Table 2 and Figures 1 and 2.

[0056] [Table 2]

[0057] (evaluation) The results shown in Table 2 reveal that Examples 1 to 3, which satisfy the requirements of the present invention, have improved moldability during inflation molding, and are excellent in the tensile modulus, dirt drop impact, and blocking of the monolayer film. [Industrial Applicability]

[0058] Packaging materials made from the polyethylene resin composition of the present invention can be suitably used as sealant films for food packaging, standing pouches, BIBs, inner bags, agricultural films, etc., and are therefore highly useful industrially.

Claims

1. A polyethylene resin composition containing a polyethylene resin that satisfies the following requirements (1) to (6): (1) The melt flow rate (MFR: 190°C, load 2.16 kg) is 1.0 to 10.0 g / 10 min. (2) Density is 0.910 g / cm ３ 0.930g / cm or more ３ is less than. (3) The ratio of the melt flow rate (HLMFR) measured at a temperature of 190°C under a load of 21.6 kg to the melt flow rate (MFR) measured at a temperature of 190°C under a load of 2.16 kg is 30 or less. (4) In a double logarithmic plot of the extensional viscosity η(t) (unit: Pa·sec) measured at a temperature of 170°C and an extensional strain rate of 2 (unit: 1 / sec) versus the extension time t (unit: sec), the maximum extensional viscosity after strain hardening is determined as η Ｍａｘ (t1), the approximate line of the extensional viscosity before curing is η Ｌｉｎｅａｒ (t1), then η Ｍａｘ (t1) / η Ｌｉｎｅａｒ The strain hardening degree [λ] defined by (t1) ｍａｘ (2.0)] is 3.0 or more. (5) In the plot of storage modulus (unit: MPa) measured at a temperature of 170°C and angular frequency (unit: rad / s), the storage modulus (E ０．１ ) and storage modulus at an angular frequency of 100 rad / s (E １００ ) The slope of the line passing through these two points is 1100 or less. (6) The molecular weight distribution (Mw / Mn), which is the ratio of the number average molecular weight (Mn) to the weight average molecular weight (Mw), determined by GPC (Gel Permeation Chromatography), is 2.5 to 5.

0.

2. 2. The polyethylene resin composition according to claim 1, wherein the polyethylene resin further satisfies the following requirements (7) and (8): (7) The ratio of the melt flow rate (HLMFR) measured at a temperature of 190°C and a load of 21.6 kg to the melt flow rate (MFR) measured at a temperature of 190°C and a load of 2.16 kg is 17 to 25. (8) In the plot of storage modulus (unit: MPa) measured at a temperature of 170°C and angular frequency (unit: rad / s), the storage modulus (E ０．１ ) and storage modulus at an angular frequency of 100 rad / s (E １００ ) The slope of the line passing through these two points is 800 to 1000.

3. The polyethylene resin composition according to claim 2, wherein the polyethylene resin further satisfies the following requirement (9): (9) In a double logarithmic plot of the extensional viscosity η(t) (unit: Pa·sec) measured at a temperature of 170°C and an extensional strain rate of 2 (unit: 1 / sec) versus the extension time t (unit: sec), the maximum extensional viscosity after strain hardening is determined as η Ｍａｘ (t1), the approximate line of the extensional viscosity before curing is η Ｌｉｎｅａｒ (t1), then η Ｍａｘ (t1) / η Ｌｉｎｅａｒ The strain hardening degree [λ] defined by (t1) ｍａｘ (2.0)] is 4.0 to 15.

0.

4. A film obtained by using the polyethylene resin composition according to any one of claims 1 to 3.

5. 5. The film of claim 4, wherein the content of an antiblocking agent is 2000 ppm or less and the content of a slip agent is 300 ppm or less.

6. A multilayer film having at least one layer comprising the film of claim 4.

7. A packaging film comprising at least one layer of the film according to claim 4.

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