Ethylene polymer, method for producing ethylene polymer, and film

Abstract

To provide an ethylene-based polymer capable of obtaining a film in which thickness unevenness is reduced, a method of producing the ethylene-based polymer, and a film containing the ethylene-based polymer.SOLUTION: In the ethylene-based polymer according to the present invention, the following Expressions (1) and (2) are satisfied: 0.362≤ηL1256% / ηL10%≤0.466 (1) and 0.0282≤I52506% / I12506%≤0.0328 (2).SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to an ethylene-based polymer, a method for producing the ethylene-based polymer, and a film containing the ethylene-based polymer. [Background technology]

[0002] Conventionally, laminate films in which a base film and a film composed of an ethylene-based polymer are laminated by melt-extruding a resin composition containing an ethylene-based polymer onto the base film have been widely used as films for packaging foods, etc. Such films composed of an ethylene-based polymer are preferably used as a sealant layer when used on the surface of the laminate film and as an adhesive layer when used inside the laminate film, and therefore are required to be excellent in transparency and adhesive strength.

[0003] As an ethylene-based polymer material used in a laminate film, for example, Patent Document 1 discloses a polyethylene-based resin material for lamination, which is characterized by being obtained by modifying 100 parts by weight of a polyethylene-based resin composition consisting of 5 to 95% by weight of a polyethylene-based resin produced by high-pressure radical polymerization and 95 to 5% by weight of a polyethylene-based resin produced by high-pressure radical polymerization other than the polyethylene-based resin by blending 0.001 to 1.0 part by weight of a radical generator. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2010-144134 A Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, in order to improve the transparency and adhesive strength of a film made of an ethylene-based polymer, it is required to reduce the unevenness in thickness of the film and improve the flatness of the film. However, the film made of an ethylene-based polymer of Patent Document 1 has a problem in that it has a large unevenness in thickness.

[0006] The present invention has been made in view of the above problems, and an object of the present invention is to provide an ethylene-based polymer capable of producing a film having reduced thickness unevenness, a method for producing the ethylene-based polymer, and a film containing the ethylene-based polymer. [Means for solving the problem]

[0007] The ethylene polymer according to the present invention satisfies the following formulae (1) and (2). 0.362≦ηL 1256% / ηL 10% ≦0.466 (1) (In the formula, ηL 10% is the strain γ of an ethylene polymer measured by the LAOS method at 150°C and 0.05Hz. 0 = 10% represents the viscosity (Pa sec) at the fastest shear rate. ηL 1256% is the strain γ of an ethylene polymer measured by the LAOS method at 150°C and 0.05Hz. 0 = 1256% represents the viscosity (Pa sec) at the fastest shear rate.) 0.0282≦I5 2506% / I1 2506% ≦0.0328 (2) (In the formula, I1 2506% is the strain γ of an ethylene polymer measured by the LAOS method at 150°C and 0.05Hz. 0 = 2506%. I5 2506% is the strain γ of an ethylene polymer measured by the LAOS method at 150°C and 0.05Hz. 0This represents the intensity of the fifth harmonic wave obtained by Fourier transforming the response stress at =2506%.)

[0008] The method for producing an ethylene-based polymer according to the present invention is a method for producing the above-mentioned ethylene-based polymer, comprising: A (°C), and the molten mixture obtained in the step (A) is heated to a temperature T B (°C), and the molten mixture obtained in step (B) is heated to a temperature T C and step (C) of melt-kneading the mixture at a temperature of 20° C., and the mixture satisfies the following formula (11): T A <T B <T C (11)

[0009] The film according to the present invention contains the above-mentioned ethylene-based polymer. Effect of the Invention

[0010] According to the present invention, it is possible to provide an ethylene-based polymer capable of producing a film having reduced thickness unevenness, a method for producing the ethylene-based polymer, and a film containing the ethylene-based polymer. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described, however, the present invention is not limited to the following embodiment.

[0012] <Ethylene-based polymer> The ethylene polymer according to this embodiment satisfies the following formulas (1) and (2). 0.362≦ηL 1256% / ηL 10% ≦0.466 (1) (In the formula, ηL 10% is the strain γ of an ethylene polymer measured by the LAOS method at 150°C and 0.05Hz. 0= 10% represents the viscosity (Pa sec) at the fastest shear rate. ηL 1256% is the strain γ of an ethylene polymer measured by the LAOS method at 150°C and 0.05Hz. 0 = 1256% represents the viscosity (Pa sec) at the fastest shear rate.) 0.0282≦I5 2506% / I1 2506% ≦0.0328 (2) (In the formula, I1 2506% is the strain γ of an ethylene polymer measured by the LAOS method at 150°C and 0.05Hz. 0 = 2506%. I5 2506% is the strain γ of an ethylene polymer measured by the LAOS method at 150°C and 0.05Hz. 0 This represents the intensity of the fifth harmonic wave obtained by Fourier transforming the response stress at =2506%.)

[0013] Here, the LAOS (Large Amplitude Oscillatory Shear) method is a technique in which a large and fast shear strain is applied to a sample and the response stress is observed and analyzed.

[0014] ηL means viscosity, i.e., the response stress at the fastest deformation rate is divided by the deformation rate at that time when a sinusoidal shear strain (deformation) is applied to a sample and a Lissajous curve is created by plotting the deformation rate and the response stress. When this ηL is measured while changing the magnitude of the shear strain (deformation), it changes according to the structure of the ethylene-based polymer. Specifically, when the shear strain (deformation) is increased, the ethylene-based polymer is oriented in the shear direction (deformation direction), so ηL decreases. The degree of decrease in ηL varies depending on the ease of orientation of the ethylene-based polymer in the shear direction (deformation direction). If the ethylene-based polymer is difficult to orient in the shear direction (deformation direction), it means that the ethylene-based polymer is entangled and difficult to move, so ηL 1256% / ηL 10%is a parameter that reflects the amount of entangled branched structures.

[0015] ηL 10% The measurement of ηL is usually performed by applying 6 cycles of a sine wave shear strain of 0.05 Hz to the sample, and the average value of the last 3 cycles is taken as the measured value. 10% The measurement typically takes 120 seconds.

[0016] ηL 1256% The measurement of ηL is usually performed by applying 6 cycles of a sine wave shear strain of 0.05 Hz to the sample, and the average value of the last 3 cycles is taken as the measured value. 1256% The measurement typically takes 120 seconds.

[0017] Usually, ηL 10% The strain γ 0 The measurement of ηL is carried out while gradually increasing the strain γ 0 = 10% to 100% in 10 logarithmically spaced steps (i.e., γ 0 = 10%, 13%, 16%, 20%, 25%, 32%, 40%, 50%, 63%, 79%, 100%), and ηL are measured. Similarly, the strain γ 0 ηL is measured while increasing the logarithmic value from 100% to 1000% in 10 equally spaced steps. 0 = 1000% to 10000% in 10 equally spaced logarithmic steps, and ηL is measured. As described above, the time required for one ηL measurement is usually 120 seconds.

[0018] ηL 1256% / ηL 10% can be increased by increasing the amount of the radical initiator to more than 0.03 mass % in the production method of the ethylene polymer described later, and can be decreased by decreasing the amount of the radical initiator to less than 0.03 mass %.

[0019] The ratio of the intensity of the fifth harmonic wave to the intensity of the reference wave (I5 / I1) changes according to the structure of the ethylene polymer. Specifically, the greater the distribution (bias) of the entangled branched structures of the ethylene polymer, the greater the I5 / I1 tends to be. Therefore, I5 2506% / I1 2506% is considered to be a parameter that reflects the distribution (bias) of intertwined branched structures.

[0020] Strain γ 0 The response stress at γ = 2506% is usually measured by applying 6 cycles of a 0.05Hz sinusoidal shear strain to the sample and taking the average value of the last 3 cycles. 0 The time required to measure the response stress at =2506% is typically 120 seconds.

[0021] As above, the strain γ 0 The response stress at γ = 10% was measured first. 0 The response stress is measured while gradually increasing the strain γ 0 The response stress is measured while increasing the stress in 10 logarithmically equal steps: 10% to 100%, 100% to 1000%, and 1000% to 10000%. As mentioned above, the time required to measure one response stress is usually 120 seconds.

[0022] I5 2506% / I1 2506% is the temperature T C The value can be increased by increasing the temperature T C The value can be reduced by lowering the temperature to below 210°C.

[0023] From the viewpoint of further reducing unevenness in thickness of the film, the ethylene polymer according to this embodiment preferably satisfies the following formulae (1') and (2'), and more preferably satisfies the following formulae (1'') and (2''). 0.370≦ηL 1256% / ηL 10% ≦0.466 (1') 0.370≦ηL 1256% / ηL 10% ≦0.440 (1'') 0.0282≦I5 2506% / I1 2506% ≦0.0320 (2') 0.0300≦I5 2506% / I1 2506% ≦0.0320 (2'')

[0024] From the viewpoint of processing stability, the ethylene polymer according to this embodiment preferably has a melt flow rate (MFR) of 2 g / 10 min or more and 6 g / 10 min or less, more preferably 3 g / 10 min or more and 5 g / 10 min or less, measured at a temperature of 190° C. and a load of 2.16 kg. The MFR is measured by Method A specified in JIS K7210-1 at a temperature of 190° C. and a load of 2.16 kg.

[0025] From the viewpoint of processing stability, the ethylene polymer according to this embodiment preferably has a molecular weight distribution of 3 or more and 15 or less, more preferably 5 or more and 13 or less. The molecular weight distribution is the ratio (Mw / Mn) of the polystyrene-equivalent weight average molecular weight Mw to the polystyrene-equivalent number average molecular weight Mn, measured by gel permeation chromatography (GPC).

[0026] The GPC measurement was carried out under the following conditions, and the baseline on the chromatogram was defined and the peaks were assigned based on the description in ISO16014-1.

[0027] (Measurement conditions) Equipment: HLC-8121GPC / HT (Tosoh Corporation) GPC column: TOSOH TSKgelGMH6-HT 7.8mm ID x 300mm (Tosoh Corporation) x 3 Mobile phase: Orthodichlorobenzene (Wako Pure Chemical Industries, special grade) with 0.1 w / V BHT added Flow rate: 1mL / min Column oven temperature: 140°C Detection: Refractive index detector (RID) RID cell temperature: 140℃ Sample solution injection volume: 300 μL Sample solution concentration: 1mg / mL GPC column calibration standard material: Standard polystyrene manufactured by Tosoh Corporation was weighed out in the combinations shown in Table 1 below, and 5 mL of orthodichlorobenzene (same composition as the mobile phase) was added for each combination and dissolved at room temperature to prepare the solution.

[0028] [Table 1]

[0029] The ethylene polymer according to this embodiment preferably has a crosslinked structure from the viewpoint of further reducing unevenness in thickness of the film.

[0030] Moreover, the ethylene-based polymer according to the present embodiment is preferably a high-pressure low-density polyethylene from the viewpoint of further reducing unevenness in thickness of the film.

[0031] High-pressure low-density polyethylene is low-density polyethylene produced by high-pressure radical polymerization. In general, high-pressure low-density polyethylene is produced by continuously polymerizing ethylene monomers in a pressure-resistant polymerization reactor at 150 to 300°C under a pressure of 1000 to 2500 atm in the presence of oxygen or an organic peroxide as a polymerization initiator.

[0032] From the viewpoint of reducing the extrusion load during film formation, the MFR of the high-pressure low-density polyethylene is preferably 4 g / 10 min or more and 30 g / 10 min or less, more preferably 6 g / 10 min or more and 30 g / 10 min or less, and even more preferably 6 g / 10 min or more and 25 g / 10 min or less.

[0033] The density of high-pressure low-density polyethylene is 910 kg / m 3 More than 930kg / m 3 It is preferable that the sintering strength is 912 kg / m or less. 3 More than 925kg / m 3More preferably, it is 915 kg / m or less. 3 More than 920kg / m 3 It is more preferable that the density is not more than 100%. The density is measured according to the method specified in Method A of JIS K7112-1980 after annealing as described in JIS K6760-1995.

[0034] The molecular weight distribution of the high-pressure low-density polyethylene is preferably from 5.0 to 15.0, and more preferably from 7.0 to 10.0.

[0035] The melt flow rate ratio (MFRR) of the high-pressure low-density polyethylene is preferably 25 or more and less than 60, and more preferably 30 or more and 45 or less. Here, MFRR means the ratio of H-MFR to MFR. H-MFR is measured by Method A specified in JIS K7210-1 under conditions of a temperature of 190°C and a load of 21.60 kg.

[0036] The ethylene-based polymer according to the present embodiment may be an ethylene-vinyl acetate copolymer, which is a copolymer having monomer units based on ethylene and monomer units based on vinyl acetate.

[0037] The MFR of the ethylene-vinyl acetate copolymer is preferably 10 g / 10 min or more and 30 g / 10 min or less, and more preferably 15 g / 10 min or more and 25 g / 10 min or less.

[0038] The content of monomer units based on vinyl acetate contained in the ethylene-vinyl acetate copolymer is preferably 10% by mass or more and 30% by mass or less, and more preferably 15% by mass or more and 25% by mass or less, relative to 100% by mass of the ethylene-vinyl acetate copolymer.

[0039] The molecular weight distribution of the ethylene-vinyl acetate copolymer is preferably 3.0 or more and 7.0 or less, and more preferably 3.5 or more and 5.0 or less.

[0040] The MFRR of the ethylene-vinyl acetate copolymer is preferably 25 or more and less than 60, and more preferably 30 or more and 50 or less.

[0041] Examples of methods for producing ethylene-vinyl acetate copolymers include high-pressure radical polymerization, in which ethylene and vinyl acetate are copolymerized in the presence of a radical generator at 50 to 400 MPa and 100 to 300° C. in the presence or absence of a suitable solvent or chain transfer agent. By adjusting the polymerization conditions for the high-pressure radical polymerization, it is possible to control the MFR or molecular weight distribution of the ethylene-vinyl acetate copolymer, or the content of monomer units based on vinyl acetate in the ethylene-vinyl acetate copolymer.

[0042] The ethylene-based polymer according to this embodiment may contain a thermoplastic resin and a thermoplastic elastomer different from the high-pressure low-density polyethylene and the ethylene-vinyl acetate copolymer.

[0043] Examples of thermoplastic resins and thermoplastic elastomers different from the high-pressure low-density polyethylene and ethylene-vinyl acetate copolymer include linear low-density polyethylene, very low-density polyethylene, ethylene-α-olefin copolymer, ethylene-(meth)acrylic acid copolymer, metal salts of ethylene-(meth)acrylic acid copolymer, ethylene-methyl methacrylate copolymer, and ethylene-propylene copolymer rubber.

[0044] The content of the thermoplastic resin and thermoplastic elastomer different from the high-pressure low-density polyethylene and the ethylene-vinyl acetate copolymer is preferably 5 mass% or less, and more preferably 2 mass% or less, relative to 100 mass% of the total mass of the resin components contained in the ethylene-based polymer according to this embodiment.

[0045] The ethylene-based polymer according to the present embodiment may contain additives such as antioxidants, lubricants, antistatic agents, processability improvers, antiblocking agents, weather resistance stabilizers, release agents, flame retardants, metal soaps, waxes, mildew inhibitors, antibacterial agents, fillers, and foaming agents, as necessary.

[0046] Examples of the antioxidant include 2,6-di-t-butyl-p-cresol (BHT), tetrakis[methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]methane (manufactured by Ciba Specialty Chemicals, trade name: IRGANOX (registered trademark) 1010), and n-octadecyl-3-(4'-hydroxy-3,5'-di-t-butylphenyl)propionate (manufactured by Ciba Specialty Chemicals, trade name: IRGANOX (registered trademark) Examples of the antioxidant include phenol-based stabilizers such as bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite and tris(2,4-di-t-butylphenyl)phosphite, and phenol-phosphite bifunctional stabilizers such as 6-[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propoxy]-2,4,8,10-tetra-t-butyldibenzo[d,f][1,3,2]dioxaphosphepine (manufactured by Sumitomo Chemical Co., Ltd., product name: Sumilizer (registered trademark) GP). The content of the antioxidant is preferably 0.001% by mass or more and 1% by mass or less, and more preferably 0.01% by mass or more and 0.1% by mass or less, based on 100% by mass of the total mass of the ethylene polymer.

[0047] Examples of the lubricant include erucic acid amide, higher fatty acid amide, higher fatty acid ester, etc. The content of the lubricant is preferably 0.01% by mass or more and 1% by mass or less, and more preferably 0.05% by mass or more and 0.5% by mass or less, relative to 100% by mass of the total mass of the ethylene polymer.

[0048] Examples of the antistatic agent include glycerin esters, sorbitan acid esters, and polyethylene glycol esters of fatty acids having 8 to 22 carbon atoms. The content of the antistatic agent is preferably 0.01% by mass or more and 1% by mass or less, and more preferably 0.1% by mass or more and 0.5% by mass or less, relative to 100% by mass of the total mass of the ethylene-based polymer.

[0049] Examples of the processability improver include fatty acid metal salts such as calcium stearate. The content of the processability improver is preferably 0.01% by mass or more and 1% by mass or less, and more preferably 0.1% by mass or more and 0.5% by mass or less, relative to the total mass (100% by mass) of the ethylene-based polymer.

[0050] Examples of the anti-blocking agent include silica, diatomaceous earth, calcium carbonate, talc, etc. The content of the anti-blocking agent is preferably 0.1% by mass or more and 5% by mass or less, and more preferably 0.3% by mass or more and 3% by mass or less, relative to 100% by mass of the total mass of the ethylene-based polymer.

[0051] These additives may be added to the ethylene-based polymer, or a master batch in which the additives are added to the ethylene-based polymer may be mixed with the ethylene-based polymer. When two or more ethylene-based polymers are included, the additives may be added after the two or more ethylene-based polymers are blended in advance, or may be added to one ethylene-based polymer, or may be added to each ethylene-based polymer.

[0052] <Method of producing ethylene polymer> The method for producing an ethylene-based polymer according to the present embodiment is a method for producing the above-mentioned ethylene-based polymer, comprising heating a mixture containing an ethylene-based polymer and a radical initiator to a temperature T A (°C), and the molten mixture obtained in the step (A) is heated to a temperature T B (°C), and the molten mixture obtained in step (B) is heated to a temperature T C and step (C) of melt-kneading the mixture at a temperature of 20° C., and the mixture satisfies the following formula (11): T A <T B <T C (11)

[0053] Examples of the ethylene-based polymer contained in the mixture include various ethylene-based polymers such as the above-mentioned high-pressure low-density polyethylene, ethylene-vinyl acetate copolymer, linear low-density polyethylene, very low-density polyethylene, ethylene-α-olefin copolymer, ethylene-(meth)acrylic acid copolymer, metal salt of ethylene-(meth)acrylic acid copolymer, ethylene-methyl methacrylate copolymer, and ethylene-propylene copolymer rubber.

[0054] The radical initiator contained in the mixture is preferably a peroxide, and more preferably a cyclic organic peroxide represented by the following formula (I).

[0055] [ka]

[0056] Here, R 1 ~R 6 each independently represents an alkyl group having 1 to 12 carbon atoms, a phenyl group, or an alkyl-substituted phenyl group. 1 ~R 6 is preferably an alkyl group having 1 to 12 carbon atoms. 1 ~R 6 Of these, R 1 ~R 3 are alkyl groups having the same structure, and R 4 ~R 6 More preferably, R is an alkyl group having the same structure. 1 ~R 3 is a methyl group, and R 4 ~R 6 More preferably, is an ethyl group.

[0057] The radical initiator may be an organic peroxide other than the cyclic organic peroxide represented by formula (I). Examples of organic peroxides other than the cyclic organic peroxide represented by formula (I) include dicumyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-di-(t-butylperoxy)hexane, 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3, 1,3-bis(t-butylperoxyisopropyl)benzene, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, n-butyl-4,4-bis(t-butylperoxy)valerate, benzoyl peroxide, p-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, t-butyl peroxybenzoate, t-butylperoxyisopropyl carbonate, diacetyl peroxide, lauroyl peroxide, t-butylcumyl peroxide, etc. These may be used alone or in combination of two or more. Among these, 2,5-dimethyl-2,5-di-(t-butylperoxy)hexane is preferred from the viewpoint of ease of handling.

[0058] The amount of the radical initiator, relative to the total amount of the ethylene-based polymers contained in the mixture (100% by mass), is preferably 0.03% by mass or more, more preferably 0.04% by mass or more, and even more preferably 0.05% by mass or more from the viewpoint of strength of the molded body, and is preferably 0.5% by mass or less, more preferably 0.4% by mass or less, and even more preferably 0.3% by mass or less from the viewpoint of fluidity.

[0059] temperature T A The temperature T is preferably 95° C. or higher and 130° C. or lower, more preferably 100° C. or higher and 125° C. or lower, and even more preferably 105° C. or higher and 120° C. or lower. B is preferably a temperature at which the half-life of the radical initiator exceeds 1 minute, specifically, it is preferably 130° C. or higher and 180° C. or lower, more preferably 135° C. or higher and 175° C. or lower, and even more preferably 140° C. or higher and 170° C. or lower. Cis preferably a temperature at which the half-life of the radical initiator is 1 minute or less, and specifically, from the viewpoint of productivity, it is preferably 210°C or more and 320°C or less, more preferably 220°C or more and 310°C or less, and even more preferably 230°C or more and 300°C or less.

[0060] temperature T A The time for melt kneading at temperature T (° C.) is preferably 0.1 minutes or more, more preferably 0.5 minutes or more, from the viewpoint of uniform dispersion, and is preferably 30 minutes or less, more preferably 20 minutes or less, from the viewpoint of productivity. B The time for melt kneading at temperature T (° C.) is preferably 0.1 minutes or more, more preferably 0.5 minutes or more, from the viewpoint of uniform dispersion, and is preferably 30 minutes or less, more preferably 20 minutes or less, from the viewpoint of productivity. C The time for melt kneading at (°C) is usually a time that is equal to or longer than the half-life of the organic peroxide, and specifically, from the viewpoint of strength of the molded body, it is preferably equal to or longer than 0.1 minutes, and more preferably equal to or longer than 0.5 minutes, and from the viewpoint of fluidity, it is preferably equal to or shorter than 30 minutes, and more preferably equal to or shorter than 20 minutes.

[0061] The melt-kneaded product obtained in each step is preferably in the form of pellets.

[0062] As the melt-kneading device, known devices such as a single screw extruder, a twin screw extruder, an open type mixing roll, a non-open type Banbury mixer, a heat roll, a kneader, etc. can be used. In the melt-kneading, all the components to be kneaded may be melt-kneaded at once, or a part of the components may be kneaded, and then the unselected components may be added and melt-kneaded.

[0063] In the method for producing an ethylene-based polymer according to the present embodiment, the step (A) is a step of melt-kneading using a melt-kneading extruder (a), the step (B) is a step of melt-kneading using a melt-kneading extruder (b), and the step (C) is a step of melt-kneading using a melt-kneading extruder (c), and it is preferable that the melt-kneading extruder (a), the melt-kneading extruder (b), and the melt-kneading extruder (c) are different from each other. This configuration can improve the workability.

[0064] In addition, the same melt-kneading extruder may be used in any two of the steps (A), (B), and (C), or the same melt-kneading extruder may be used in all of the steps. When the same melt-kneading extruder is used, a plurality of steps can be carried out by changing the melt-kneading temperature in the melt-kneading extruder stepwise.

[0065] <Film> The film according to this embodiment contains the above-mentioned ethylene-based polymer.

[0066] The film according to the present embodiment is a multi-layer film having a base film and a film composed of the ethylene-based polymer. The base film may be a base film of one layer or two or more layers.

[0067] Examples of the substrate film include films made of polyamide resins such as nylon 6 and nylon 66, polyester resins such as polyethylene terephthalate and polybutylene terephthalate, cellophane, paper, paperboard, textiles, aluminum foil, oriented polypropylene, polyethylene, etc. The substrate film may have an anchor coat layer. Substrate films of two or more layers can be obtained by laminating each layer by dry lamination or extrusion lamination.

[0068] The method for producing the multilayer film includes melt extruding the resin composition containing the ethylene-based polymer onto a substrate film and extrusion laminating the same. By extrusion lamination, it is possible to produce a multilayer film without molding defects such as edge cuts and film cracks. Therefore, the film according to the present embodiment has excellent film formability. Edge cuts are a phenomenon in which a molten film made of an ethylene-based polymer breaks during extrusion lamination. Film cracks are a phenomenon in which a long hole occurs in a part of a molten film made of an ethylene-based polymer in the machine direction (MD), resulting in an unlaminated portion.

[0069] The film composed of the ethylene-based polymer in the multilayer film serves as a sealant layer when used on the surface of the multilayer film, and serves as an adhesive layer when used inside the film. In addition, when a resin composition containing an ethylene-based polymer is laminated on a base film by extrusion lamination, the resin composition may be applied onto an anchor coat layer of the base film.

[0070] The thickness of the film according to this embodiment is preferably 3 μm or more and 500 μm or less, and more preferably 5 μm or more and 300 μm or less.

[0071] The ethylene-based polymer, the method for producing the ethylene-based polymer, and the film according to the present embodiment are not limited to the above embodiment, and various modifications are possible without departing from the gist of the present invention. In addition, the configurations, methods, etc. of the embodiments other than the above may be arbitrarily adopted and combined, and the configurations, methods, etc. of one of the above embodiments may be applied to the configurations, methods, etc. of the other embodiments. EXAMPLES

[0072] The present invention will be described in more detail below using examples and comparative examples, but the present invention is not limited to the following examples.

[0073] <Melt flow rate (MFR, unit: g / 10 min)> The measurement was carried out according to the method specified in JIS K7210-1, under conditions of a temperature of 190°C and a load of 2.16 kg, using Method A.

[0074] <Example 1> 80 parts by mass of pulverized powder of an ethylene polymer (Flothane FG801NN, manufactured by Sumitomo Seika Chemicals Co., Ltd.) was immersed in 20 parts by mass of a radical initiator (Trigonox301, manufactured by Kayaku Nouryon Co., Ltd.) The immersed powder was melt-kneaded at 110°C for 1 minute using a melt-kneading extruder (a) (manufactured by Uniplastics Corporation) with a screw diameter of 30 mm to produce master batch pellets (hereinafter also referred to as MB pellets).

[0075] The MB pellets obtained above were added to 100 parts by mass of an ethylene polymer (Sumitomo Chemical Co., Ltd., Sumikathene CE4506) to a concentration of 5800 ppm, and melt-kneaded at 150°C for 1 minute using a melt-kneading extruder (b) (Tanabe Plastics Machine Co., Ltd.) with a screw diameter of 40 mm to obtain pellets. The obtained pellets were melt-kneaded at 240°C for 1 minute using another melt-kneading extruder (c) (Tanabe Plastics Machine Co., Ltd.) with a screw diameter of 40 mm to obtain pellets.

[0076] The pellets obtained above were left to stand at 150°C for 5 minutes (preheating step), pressed at 150°C and 5 MPa for 5 minutes (pressing step), and slowly cooled at 25°C for 5 minutes (slow cooling step) to obtain a pressed sheet with a thickness of 0.5 mm. A circular sheet with a diameter of 8 mm was punched out from the obtained pressed sheet to prepare a measurement sample. The obtained measurement sample was measured using a dynamic viscoelasticity measuring device (TA Instruments, ARES-G2) using the LAOS method.

[0077] The measurement sample was subjected to the following conditions: temperature 150℃, frequency 0.05Hz, strain γ 0 = Viscosity at the fastest shear rate at 10% ηL 10% and strain γ 0 = 1256% viscosity at the fastest shear rate ηL 1256% ηL 10%Measurement of and ηL 1256% The measurements were performed by applying 6 cycles of a sine wave shear strain of 0.05 Hz to the test specimen, and the average value of the last 3 cycles was taken as the measured value. 10% The strain γ 0 = 10%~100%, 100%~1000%, 1000%~10000% are each increased in 10 logarithmically equal steps, while ηL 1256% The ratio ηL 1256% / ηL 10% was 0.430, satisfying equation (1).

[0078] In addition, the strain γ of the measurement sample was measured at a temperature of 150°C and a frequency of 0.05Hz. 0 The intensity I1 of the reference wave obtained by Fourier transforming the response stress at =2506% (manufactured by TA Instruments, software name: TRIOS ver5.0.0) 2506% and the intensity of the fifth harmonic I5 2506% The measurement was done. I1 2506% Measurement and I5 2506% The measurements were performed by applying a 0.05Hz sine wave shear strain to the test specimen for six cycles, and the average value of the last three cycles was taken as the measured value. 0 The response stress at γ = 10% was measured first. 0 The response stress was measured while increasing the load by logarithmically dividing the load into 10 steps of 10% to 100%, 100% to 1000%, and 1000% to 10000%. The ratio of the load to the load, I5 2506% / I1 2506% was 0.0308, which satisfied formula (2). The results are shown in Table 2.

[0079] The pellets obtained above were extrusion laminated on a 12 μm thick PET substrate using a co-extrusion laminator (manufactured by Sumitomo Heavy Industries Modern Co., Ltd.) equipped with an 800 mm wide T-die at the tip of an extruder with a screw diameter of 65 mm under the conditions of an inner width of the T-die of 500 mm, an air gap of 140 mm, a laminate thickness of the ethylene polymer of 7 μm, a temperature directly below the T-die of 333 ° C., and a lamination speed of 150 m / min. The thickness of the ethylene polymer layer of the obtained laminate sample was measured in the width direction over a 200 mm width at the center of the sample using a tabletop offline thickness meter (manufactured by Yamabun Denki Co., Ltd., TOF-5R01). The standard deviation of the obtained measured values ​​was 0.67. The results are shown in Table 2.

[0080] <Example 2> MB pellets were prepared in the same manner as in Example 1. The MB pellets obtained above were added to 100 parts by mass of an ethylene polymer (Sumitomo Chemical Co., Ltd., Sumikathene CE4506) so as to give a concentration of 2900 ppm, and melt-kneaded at 150°C using a melt-kneading extruder (b) (Tanabe Plastics Machine Co., Ltd.) with a screw diameter of 40 mm to obtain pellets. The obtained pellets were melt-kneaded at 240°C using another melt-kneading extruder (c) (Tanabe Plastics Machine Co., Ltd.) with a screw diameter of 40 mm to obtain pellets.

[0081] Using the pellets obtained above, the ηL 1256% / ηL 10% The measured value was 0.383, which satisfied formula (1). 2506% / I1 2506% The result was 0.0313, which satisfied formula (2). The results are shown in Table 2.

[0082] Using the pellets obtained above, an extrusion laminate sample was prepared in the same manner as in Example 1, and the thickness of the ethylene polymer laminate layer in the central 200 mm width was measured across the width direction. The standard deviation of the obtained measurements was 0.83.

[0083] <Example 3> MB pellets were prepared in the same manner as in Example 1. The MB pellets obtained above were added to 100 parts by mass of an ethylene polymer (Sumitomo Chemical Co., Ltd., Sumikathene CE3049) so as to give a concentration of 500 ppm, and melt-kneaded at 150°C using a melt-kneading extruder (b) (Tanabe Plastics Machine Co., Ltd.) with a screw diameter of 40 mm to obtain pellets. The obtained pellets were melt-kneaded at 240°C using another melt-kneading extruder (c) (Tanabe Plastics Machine Co., Ltd.) with a screw diameter of 40 mm to obtain pellets.

[0084] Using the pellets obtained above, the ηL 1256% / ηL 10% The measured value was 0.463, which satisfied formula (1). 2506% / I1 2506% The result was 0.0284, which satisfied formula (2). The results are shown in Table 2.

[0085] Using the pellets obtained above, an extrusion laminate sample was prepared in the same manner as in Example 1, and the thickness of the ethylene polymer laminate layer in the central 200 mm width was measured across the width direction. The standard deviation of the obtained measurements was 0.53.

[0086] <Comparative Example 1> A dipped powder was prepared in the same manner as in Example 1. The dipped powder obtained above was added to 100 parts by mass of an ethylene polymer (Sumikathene CE4506, manufactured by Sumitomo Chemical Co., Ltd.) so as to have a concentration of 5800 ppm, and after pre-kneading, the mixture was melt-kneaded at 240°C using a melt-kneading extruder (c) (manufactured by Tanabe Plastics Machine Co., Ltd.) with a screw diameter of 40 mm to obtain pellets.

[0087] Using the pellets obtained above, the ηL 1256% / ηL 10% The measured value was 0.438, which satisfied formula (1). On the other hand, I5 2506% / I12506% The result was 0.0329, which did not satisfy formula (2). The results are shown in Table 2.

[0088] Using the pellets obtained above, an extrusion laminate sample was prepared in the same manner as in Example 1, and the thickness of the ethylene polymer layer in the central 200 mm width in the width direction was measured. The standard deviation of the obtained measurements was 1.05, and thickness unevenness occurred.

[0089] <Comparative Example 2> Using pellets of an ethylene polymer (Sumitomo Chemical Co., Ltd., Sumikathene L420), the ηL 1256% / ηL 10% The measured value was 0.361, which did not satisfy formula (1). 2506% / I1 2506% The result was 0.0329, which did not satisfy formula (2). The results are shown in Table 2.

[0090] Using the pellets, an extrusion laminate sample was prepared in the same manner as in Example 1, and the thickness of the ethylene polymer layer in the central 200 mm width in the width direction was measured. The standard deviation of the obtained measurements was 1.45, and thickness unevenness occurred.

[0091] [Table 2]

Claims

1. Satisfying the following formulas (1) and (2), It is a high-pressure low-density polyethylene. An ethylene polymer having a melt flow rate of 2 g / 10 min or more and 6 g / 10 min or less, measured under conditions of a temperature of 190° C. and a load of 2.16 kg. 0.362≦ηL １２５６％ / ηL １０％ ≦0.466 (1) (In the formula, ηL １０％ is the strain γ of an ethylene polymer measured by the LAOS method at 150 °C and 0.05 Hz. ０ = The viscosity (Pa·sec) at the fastest shear rate at 10%. ηL １２５６％ is the strain γ of an ethylene polymer measured by the LAOS method at 150 °C and 0.05 Hz. ０ = 1256% represents the viscosity (Pa sec) at the fastest shear rate. 0.0282≦I5 ２５０６％ / I1 ２５０６％ ≦0.0328 (2) (In the formula, I1 ２５０６％ is the strain γ of an ethylene polymer measured by the LAOS method at 150 °C and 0.05 Hz. ０ This represents the intensity of the reference wave obtained by Fourier transform of the response stress at 2506%. I5 ２５０６％ is the strain γ of an ethylene polymer measured by the LAOS method at 150 °C and 0.05 Hz. ０ (This represents the intensity of the fifth harmonic wave obtained by Fourier transform of the response stress at 2506%.)

2. The ethylene polymer according to claim 1, which satisfies the following formulas (1') and (2'): 0.370≦ηL １２５６％ / ηL １０％ ≦0.466 (1’) 0.0282≦I5 ２５０６％ / I1 ２５０６％ ≦0.0320 (2')

3. The ethylene polymer according to claim 1 or 2, which satisfies the following formulas (1″) and (2″): 0.370≦ηL １２５６％ / ηL １０％ ≦0.440 (1’’) 0.0300≦I5 ２５０６％ / I1 ２５０６％ ≦0.0320 (2'')

4. The ethylene polymer according to any one of claims 1 to 3, which has a crosslinked structure.

5. A method for producing the ethylene polymer according to any one of claims 1 to 4, comprising the steps of: The mixture containing the ethylene polymer and the radical initiator is heated to a temperature T Ａ (A) a step of melt-kneading at (°C); The melt-kneaded product obtained in the step (A) is heated to a temperature T Ｂ (B) a step of melt-kneading at (°C); The melt-kneaded product obtained in the step (B) is heated to a temperature T Ｃ (C) a step of melt-kneading at (°C); Including, A method for producing an ethylene-based polymer, which satisfies the following formula (11): T Ａ <T Ｂ <T Ｃ (11)

6. The step (A) is a step of melt-kneading using a melt-kneading extruder (a), The step (B) is a step of melt-kneading using a melt-kneading extruder (b), The step (C) is a step of melt-kneading using a melt-kneading extruder (c), The method for producing an ethylene-based polymer according to claim 5, wherein the melt-kneading extruder (a), the melt-kneading extruder (b) and the melt-kneading extruder (c) are different from each other.

7. 7. The method for producing an ethylene-based polymer according to claim 5 or 6, wherein the step (A) is a step of melt-kneading a mixture containing an ethylene-based polymer and a radical initiator with the ethylene-based polymer.

8. The method for producing an ethylene-based polymer according to any one of claims 5 to 7, wherein the radical initiator is a peroxide.

9. A film comprising the ethylene polymer according to any one of claims 1 to 4.

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