Polyethylene composition and molded article

Abstract

To provide a polyethylene composition having excellent high-speed thin-film forming properties and heat resistant pinhole property and having less thickness irregularity.SOLUTION: There is provided a polyethylene composition satisfying the following conditions (A) to (D).<Condition (A)> The MFR is 1.0 g / 10 min to 20.0 g / 10 min. <Condition (B)> The density is 925 to 970 kg / m3.<Condition (C)> When the heat of fusion by a temperature-heat flow curve obtained by the 1st scan of DSC measured within 24 hours after the prescribed pretreatment is defined as ΔHS1 and the heat of fusion by a temperature-heat flow curve obtained by the 2nd scan is defined as ΔHS2, ΔHS1 and ΔHS2 are 110 J / g to 240 J / g and the value of ΔHS1 / ΔHS2 is 1.000 to 1.100.<Condition (D)> When the heat of fusion by a temperature-heat flow curve obtained by the 1st scan of DSC measured within 24 hours after the prescribed pretreatment is defined as ΔHT1, the value of ΔHT1 is 110 J / g to 240 J / g and the value of ΔHS1 / ΔHT1 is 1.000 to 1.100.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a polyethylene composition and a molded article. [Background technology]

[0002] Polyethylene compositions are molded by various molding methods and used in a wide range of applications, and the properties required vary depending on the molding method and application. It is generally known that different polyethylenes are mixed to adjust the properties required.

[0003] For example, density 942 kg / m 3 High density polyethylene with a density of 930kg / m 3 By blending the following low-density polyethylenes, it is possible to obtain a polyethylene composition that combines the rigidity and heat resistance of high-density polyethylene with the flexibility and processing stability of low-density polyethylene (see, for example, Patent Document 1). Furthermore, blending high-density polyethylene with low-density polyethylene makes it possible to reduce defects in films known as fish eyes (hereinafter sometimes referred to as "FE"), and a technology has been disclosed in which these features are utilized in surface protection films for optical components and heat-resistant laminates (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 4931187 [Patent Document 2] Patent No. 6243195 Summary of the Invention [Problem to be solved by the invention]

[0005] The properties of a polyethylene composition can be controlled by adjusting the type and compositional ratio of polyethylene used as raw materials. However, when multiple required properties are required, the properties generally change in a trade-off relationship depending on the compositional ratio of the raw materials. For example, when the composition ratio of high-density polyethylene is set high in order to obtain heat resistance for surface protection film applications or heat-resistant laminate applications, problems arise such as the increase in the cooling rate during film formation, resulting in the formation of wrinkles and unevenness, deterioration in adhesion between layers of a multilayer film or between a laminate substrate and the polyethylene composition, and deterioration in processability. If the composition ratio of high-density polyethylene is set low in an attempt to solve the above-mentioned problems, the polyethylene composition will have insufficient heat resistance. In particular, when the polyethylene composition is used for a multilayer film or a heat-resistant laminate, the balance between adhesion to the substrate and heat resistance is important, and if either one is insufficient, pinholes will be generated during heating, which is a problem.

[0006] As described above, there is a problem that a polyethylene composition having an excellent balance of properties cannot be obtained simply by adjusting the composition ratio of polyethylene used as a raw material. Furthermore, the techniques disclosed in Patent Documents 1 and 2 have not verified the above-mentioned problems, and there is room for improvement.

[0007] Furthermore, in recent years, from the viewpoint of reducing the environmental load, importance has been placed on reducing the weight and volume of products using polyethylene. In particular, there is a demand for thinner films and improved yields for polyethylene compositions used for film and laminate applications. However, polyethylene compositions have problems such as a tendency for heat resistance and adhesiveness to decrease when they are made into thin films, and the films are prone to rupture. Therefore, there is a demand for polyethylene compositions that exhibit sufficient heat resistance even in thin films and are less susceptible to film rupture even during high-speed processing.

[0008] In view of the above-mentioned problems of the prior art, an object of the present invention is to provide a polyethylene composition which has excellent high-speed thin film formability, excellent heat pinhole resistance and little thickness unevenness. [Means for solving the problem]

[0009] Means for Solving the Problems of the Prior Art As a result of intensive research by the present inventors to solve the above-mentioned problems of the prior art, it was found that a polyethylene composition having the specific properties described below can solve the above-mentioned problems of the prior art, and thus the present invention was completed. That is, the present invention is as follows.

[0010] [1] Density is 942 kg / m 3 High density polyethylene (A) or higher and a density of 930 kg / m 3 A mixture of the following high-pressure low-density polyethylenes (B): the high-pressure low-density polyethylene (B) has a relaxation time Tγ of a high-mobility component γ of 100 ms or more and 200 ms or less when a free induction decay curve obtained by a Carr-Purcell-Meiboom-Gill (CPMG) method in pulse NMR measurement at 120°C is approximated as a three-component curve, A polyethylene composition satisfying the following <Condition (A)> to <Condition (D)>: <Condition (A)> The melt flow rate at 190°C and a load of 2.16 kg is 1.0 g / 10 min or more and 20.0 g / 10 min or less. <Condition (B)> Density is 925 kg / m 3 More than 970kg / m 3 The following is the result. <Condition (C)> After carrying out the pretreatment under the following [Pretreatment Conditions (S)], the heat of fusion calculated from the temperature-heat flow curve obtained by the first scan of differential scanning calorimetry (DSC) measured within 24 hours is ΔH S1 The heat of fusion calculated from the temperature-heat flow curve obtained by the second scan is ΔH S2 When The ΔH S1 and the ΔH S2 The value is 110 J / g or more and 240 J / g or less, ΔH S1 / ΔH S2 The value of is between 1.000 and 1.100. [Pretreatment conditions (S)] According to JIS K7210 Code D:1999, the wire is processed into a strand at 190°C under a load of 2.16 kg, annealed at 120°C for 1 hour, and then air-cooled in a standard atmosphere at a temperature of 21°C to 25°C for 1 hour. It is then annealed at 100°C for 1 hour, and then air-cooled in a standard atmosphere at a temperature of 21°C to 25°C for 1 hour. <Condition (D)> After carrying out the pretreatment under the following [Pretreatment Conditions (T)], the heat of fusion calculated from the temperature-heat flow curve obtained by the first scan of differential scanning calorimetry (DSC) measured within 24 hours is ΔH T1 When The ΔH T1 The value is 110 J / g or more and 240 J / g or less, The ΔH S1 The ratio of ΔH S1 / ΔH T1 The value of is between 1.000 and 1.100. [Pretreatment conditions (T)] According to JIS K7210 Code D:1999, the wire is processed into a strand at 190°C under a load of 2.16 kg, annealed at 100°C for 1 hour, and then air-cooled in a standard atmosphere at a temperature of 21°C to 25°C for 1 hour. [2] Density is 942 kg / m 3 The above high-density polyethylene (A), Density is 930 kg / m 3 A mixture of the following high-pressure low-density polyethylenes (B): When the high-pressure low-density polyethylene (B) is measured by pulse NMR at 120°C, a free induction decay curve obtained by the Carr-Purcell Meiboom-Gill (CPMG) method is approximated as a three-component curve, The abundance ratio Rγ of the high mobility component γ is 9% or more and 24% or less, and the relaxation time Tγ of the high mobility component γ is 100 ms or more and 200 ms or less. The polyethylene composition according to [1] above. [3] Density is 942 kg / m 3 The above high-density polyethylene (A), Density is 930 kg / m 3 A mixture of the following high-pressure low-density polyethylenes (B): When the high-density polyethylene (A) is subjected to pulse NMR measurement at 100°C, a free induction decay curve obtained by a solid echo (SE) method is approximated as a three-component curve, The abundance ratio Rα of the low motility component α is 55% or more and 85% or less, And the abundance ratio Rγ of the high motility component γ is 1% or more and 10% or less. The polyethylene composition according to [1] or [2] above. [4] A molded article of the polyethylene composition according to any one of [1] to [3] above. [5] The molded article according to [4] above, which is a film-like molded article. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a polyethylene composition which has excellent high-speed thin film-forming properties, excellent heat pinhole resistance, and little thickness unevenness. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the present invention (hereinafter referred to as "the present embodiment") will be described in detail. It should be noted that the following embodiment is an example for explaining the present invention, and is not intended to limit the present invention to the following content. The present invention can be implemented in various modifications within the scope of its gist.

[0013] [Polyethylene composition] The polyethylene composition of the present embodiment satisfies the following <Condition (A)> to <Condition (D)>. <Condition (A)> The melt flow rate at 190°C and a load of 2.16 kg is 1.0 g / 10 min or more and 20.0 g / 10 min or less. <Condition (B)> Density is 925 kg / m 3 More than 970kg / m 3The following is the result. <Condition (C)> After carrying out the pretreatment under the following [Pretreatment Conditions (S)], the heat of fusion calculated from the temperature-heat flow curve obtained by the first scan of differential scanning calorimetry (hereinafter sometimes referred to as DSC) measured within 24 hours is ΔH S1 The heat of fusion calculated from the temperature-heat flow curve obtained by the second scan is ΔH S2 When The ΔH S1 , the ΔH S2 The value is 110 J / g or more and 240 J / g or less, ΔH S1 / ΔH S2 The value of is between 1.000 and 1.100. [Pretreatment conditions (S)] According to JIS K7210 Code D:1999, the wire is processed into a strand at 190°C under a load of 2.16 kg, annealed at 120°C for 1 hour, and then air-cooled in a standard atmosphere at a temperature of 21°C to 25°C for 1 hour. It is then annealed at 100°C for 1 hour, and then air-cooled in a standard atmosphere at a temperature of 21°C to 25°C for 1 hour. The standard atmosphere is defined as an air atmosphere with a temperature of 21°C to 25°C, a humidity of 40% to 60%, and an atmospheric pressure of 86 kPa to 106 kPa. <Condition (D)> After carrying out the pretreatment under the following [Pretreatment Conditions (T)], the heat of fusion calculated from the temperature-heat flow curve obtained by the first scan of differential scanning calorimetry (DSC) measured within 24 hours is ΔH T1 When The ΔH T1 The value is 110 J / g or more and 240 J / g or less, The ΔH S1 The ratio of ΔH S1 / ΔH T1 The value of is between 1.000 and 1.100. [Pretreatment conditions (T)] According to JIS K7210 Code D:1999, the wire is processed into a strand at 190°C under a load of 2.16 kg, annealed at 100°C for 1 hour, and then air-cooled in a standard atmosphere at a temperature of 21°C to 25°C for 1 hour. The standard atmosphere is defined as an air atmosphere with a temperature of 21°C to 25°C, a humidity of 40% to 60%, and an atmospheric pressure of 86 kPa to 106 kPa.

[0014] By having the above-mentioned constitution, it is possible to obtain a polyethylene composition which has excellent high-speed thin film formability and heat pinhole resistance and which has little thickness unevenness.

[0015] The polyethylene composition of the present embodiment preferably further satisfies at least one of the following <Condition (E)> to <Condition (G)>.

[0016] <Condition (E)> Density is 942 kg / m 3 High density polyethylene (A) or higher and a density of 930 kg / m 3 The following low density polyethylene (B) is a mixture:

[0017] <Condition (F)> Density is 942 kg / m 3 High density polyethylene (A) or higher and a density of 930 kg / m 3 The low-density polyethylene (B) is a mixture of the following low-density polyethylenes, wherein when the low-density polyethylene (B) is measured by pulse NMR at 120°C and the free induction decay curve obtained by the Carr Purcell Meiboom Gill (hereinafter referred to as CPMG) method is approximated as a three-component curve, the abundance ratio Rγ of high-mobility component γ is 9% or more and 24% or less, and the relaxation time Tγ of the high-mobility component γ is 100 ms or more and 200 ms or less.

[0018] <Condition (G)> Density is 942 kg / m 3 High density polyethylene (A) or higher and a density of 930 kg / m 3The high-density polyethylene (A) is a mixture of the following low-density polyethylene (B), wherein, when the free induction decay curve obtained by the Solid Echo (hereinafter referred to as SE) method in pulse NMR measurement at 100°C is approximated as a three-component curve, the abundance ratio Rα of the low-mobility component α is 55% or more and 85% or less, and the abundance ratio Rγ of the high-mobility component γ is 1% or more and 10% or less.

[0019] By satisfying at least one of the above <conditions (E) to (G)>, a polyethylene composition can be obtained which is even more excellent in high-speed thin film formability and heat pinhole resistance and which has less thickness unevenness.

[0020] The polyethylene composition of the present embodiment preferably contains polyethylene selected from the group consisting of high-density polyethylene, high-pressure low-density polyethylene, linear low-density polyethylene, and other special ultra-low-density polyethylenes. Among these, the polyethylene composition of the present embodiment has a density of 942 kg / m 3 High density polyethylene with a density of 930 kg / m or more 3 It is preferable that the polyethylene contains a high-pressure low-density polyethylene having a molecular weight of 950 kg / m or less. 3 High density polyethylene and a density of 928 kg / m 3 It is preferable that the polyethylene composition contains the following high-pressure low-density polyethylene: Such a polyethylene composition tends to have fewer fish eyes (FE) and an excellent balance between heat resistance and processability.

[0021] The polyethylene contained in the polyethylene composition of the present embodiment may be a homopolymer of ethylene, or a copolymer of ethylene with an α-olefin, a cyclic olefin, a diene, or a derivative thereof, or may contain two or more types of (co)polymers.

[0022] The method for producing the polyethylene composition of the present embodiment is not particularly limited, but examples thereof include a method of melt-kneading a high-density polyethylene produced by a slurry method and a low-density polyethylene produced by a high-pressure method. The method for producing the polyethylene as a raw material is not particularly limited, and any of the commonly used methods such as a solution method, a high-pressure method, a high-pressure bulk method, a gas method, and a slurry method may be used.

[0023] (Melt flow rate (MFR) at 190°C and a load of 2.16 kg) As shown in the above <Condition (A)>, the polyethylene composition of the present embodiment has an MFR at 190°C under a load of 2.16 kg of 1.0 g / 10 min or more and 20.0 g / 10 min or less, preferably 2.0 g / 10 min or more and 18.0 g / 10 min or less, more preferably 3.0 g / 10 min or more and 15.0 g / 10 min or less, and even more preferably 3.0 g / 10 min or more and 10.0 g / 10 min or less. When the MFR is 1.0 g / 10 min or more, film tearing of the polyethylene composition of the present embodiment can be suppressed, and adhesion to a predetermined substrate tends to be improved. When the MFR is 20.0 g / 10 min or less, neck-in tends to be small. The MFR of the polyethylene composition can be controlled by adjusting the polymerization conditions for polyethylene, and can be controlled within the above-mentioned range by selecting the types of raw materials and adjusting the mixing ratio.

[0024] (density) As shown in the above <Condition (B)>, the polyethylene composition of the present embodiment has a density of 925 kg / m 3 More than 970kg / m 3 Preferably, it is 930 kg / m or less. 3 More than 968kg / m 3 More preferably, it is 932 kg / m or less. 3 More than 968kg / m 3 More preferably, it is 935 kg / m or less. 3 More than 965kg / m 3 The following is the result. Density is 930 kg / m 3 When the density is 970 kg / m or more, the heat resistance and stiffness of a film produced using the polyethylene composition of the present embodiment tend to be improved. 3When the amount is equal to or less than this, strand stability during pellet production tends to be improved, and film shaking during film formation tends to be reduced. The density of the polyethylene composition is measured in accordance with JIS K7112, and specifically, can be measured by the method described in the examples below. The density of the polyethylene composition can generally be controlled by adjusting the polymerization conditions, and can be controlled within the above-mentioned range by selecting the types of raw materials and adjusting the mixing ratio.

[0025] (The heat of fusion obtained by differential scanning calorimetry (DSC), ΔH S1 , ΔH S2 , ΔH S1 / ΔH S2 ) As shown in the above <Condition (C)>, the polyethylene composition of the present embodiment is subjected to the pretreatment under the following [Pretreatment Condition (S)], and then the heat of fusion calculated from the temperature-heat flow curve obtained by the first scan of differential scanning calorimetry (DSC) measured within 24 hours is ΔH S1 The heat of fusion calculated from the temperature-heat flow curve obtained by the second scan is ΔH S2 When the above ΔH S1 , and the ΔH S2 The value of is 110J / g or more and 240J / g or less, and ΔH S1 / ΔH S2 The value of is between 1.000 and 1.100. [Pretreatment conditions (S)] According to JIS K7210 Code D:1999, the wire is processed into a strand at 190°C under a load of 2.16 kg, annealed at 120°C for 1 hour, and then air-cooled in a standard atmosphere at a temperature of 21°C to 25°C for 1 hour. It is then annealed at 100°C for 1 hour, and then air-cooled in a standard atmosphere at a temperature of 21°C to 25°C for 1 hour.

[0026] ΔH S1 , and ΔH S2 The value of ΔH is preferably 120 J / g or more, more preferably 130 J / g or more. Also, it is preferably 230 J / g or less, more preferably 220 J / g or less. S1 , and ΔHS2 When the value of is within the above range, the polyethylene composition of the present embodiment tends to have excellent heat resistance and processability when laminated.

[0027] Also, ΔH S1 / ΔH S2 The value of ΔH is preferably 1.008 or more, more preferably 1.015 or more, and even more preferably 1.020 or more. It is also preferably 1.090 or less, more preferably 1.080 or less, even more preferably 1.070 or less, and even more preferably 1.055 or less. S1 / ΔH S2 When the value of is 1.000 or more, when the polyethylene composition of the present embodiment is laminated, the adhesiveness to the substrate improves, and further, breakage during thin film processing tends to be reduced. Also, ΔH S1 / ΔH S2 When the value is 1.100 or less, the heat resistance of the molded article tends to be improved. ΔH S1 / ΔH S2 When the value of is within the above range, the polyethylene composition of the present embodiment tends to have an excellent balance between the adhesion to a substrate and the heat resistance when laminated, and therefore the heat pinhole resistance tends to be improved. The pretreatment method and DSC measurement method applied to the measurement of the polyethylene composition of this embodiment can be carried out by the methods described in the Examples below.

[0028] The ΔH S1 is the heat of fusion calculated from the temperature-calorie curve obtained by the first scan of the DSC measured within 24 hours after carrying out the [pretreatment condition (S)]. The [pretreatment condition (S)] is an operation of annealing at 120°C, air-cooling, and then annealing at 100°C, followed by air-cooling, which can crystallize the high-density polyethylene component and the low-density polyethylene component contained in the polyethylene composition of the present embodiment. S1indicates "the heat of fusion of the high-density polyethylene component and the low-density polyethylene component contained in the polyethylene composition in a crystallized state."

[0029] The ΔH S2 is the heat of fusion calculated from the temperature-heat flow curve obtained by the second scan, and the ΔH S1 The heat of fusion is measured when a sample melted in the measurement is cooled at a constant rate to crystallize it and then melted again.

[0030] The polyethylene composition of the present embodiment has a ΔH S1 / ΔH S2 The value of is between 1.000 and 1.100, which is the ΔH S2 The value of ΔH S1 This shows that the value is smaller than the value of . This phenomenon can be explained as follows.

[0031] The ΔH S2 During the process of cooling a molten sample during measurement, the high-density polyethylene component contained in the polyethylene composition of the present embodiment has a higher melting point than the low-density polyethylene component, and therefore crystallization proceeds earlier than the low-density polyethylene component. Meanwhile, at this point, the low-density polyethylene component contained in the polyethylene composition of the present embodiment is in a molten state. Here, when the molecular mobility of the low-density polyethylene component is high, it is thought that the movement inhibits the crystallization of the high-density polyethylene component. Subsequently, the crystallization of the low-density polyethylene progresses, but at this point, the high-density polyethylene is in a crystallized state. Therefore, when the molecular mobility of the high-density polyethylene component is low, it is thought that the low-density polyethylene component can only crystallize in the intercrystalline spaces of the high-density polyethylene component.

[0032] As described above, when the molecular mobility of low-density polyethylene is high, the crystallization of the high-density polyethylene component is inhibited by the molecular motion of the low-density polyethylene in the molten state during the cooling process of the molten sample. As a result, the crystallinity of the polyethylene composition decreases, and ΔHS2 The value also tends to be lower. On the other hand, ΔH S1 The value of ΔH is the degree of crystallinity measured in a state in which the polyethylene composition has been crystallized by annealing, and is therefore not affected by the above-mentioned inhibition. S1 / ΔH S2 The value of ΔH indicates the magnitude of the effect of inhibiting crystallization due to the molecular mobility of each component contained in the polyethylene composition. S1 / ΔH S2 If the value is 1.000 or more, the ΔH S2 The value of ΔH S1 This indicates that the value is smaller than

[0033] Polyethylene compositions that are significantly affected by crystallization inhibition due to molecular motion tend to have improved adhesion to paper and good heat pinhole resistance in thin films due to crystallization inhibition during the cooling process of melt lamination onto paper. Furthermore, crystallization inhibition slows the cooling rate, which tends to reduce thickness unevenness. Furthermore, crystallization inhibition extends the stress relaxation time, which tends to stabilize film-forming processability and suppress breakage during high-speed film formation.

[0034] ΔH S1 , ΔH S2 , and ΔH S1 / ΔH S2 Examples of methods for controlling the value include a method in which the polymer structures of the high-density polyethylene and the low-density polyethylene contained in the polyethylene composition are precisely controlled, and the molecular mobility at each temperature is appropriately controlled, and then the polyethylene composition is produced using an appropriate composition ratio and mixing method.

[0035] The low-density polyethylene contained in the polyethylene composition of this embodiment preferably has a polymer structure that exhibits high molecular mobility in the temperature range in which the high-density polyethylene component crystallizes, and that is capable of inhibiting the crystallization of the high-density polyethylene. For example, low-density polyethylene in which the degree of polymerization of long-chain branched components is non-uniform tends to inhibit the crystallization of the high-density polyethylene due to more complex molecular motion. Furthermore, low-density polyethylene having a hyperbranched structure in which further long-chain branched structures are formed in addition to the long-chain branched structure tends to inhibit the crystallization of the high-density polyethylene due to more complex molecular motion. When the polyethylene composition of this embodiment contains such a low-density polyethylene, ΔH S1 / ΔH S2 The value of can be controlled within the above-mentioned range. Furthermore, the molecular mobility can be evaluated by pulse NMR, which will be described later.

[0036] Methods for producing the above-mentioned low-density polyethylene include, but are not limited to, methods of adjusting reaction conditions such as polymerization temperature, polymerization pressure, type of reaction initiator, presence or absence of a chain transfer agent, and mixing ratio of polymerized polymer and unreacted gas. For example, if the degree of polymerization at the start of polymerization is high and multiple reaction initiation points are provided in a polymerization reactor with a temperature difference between the most upstream and most downstream points, polymers with different degrees of polymerization are produced at each reaction initiation point, and these are incorporated as long-chain branched structures, resulting in low-density polyethylene with a non-uniform degree of polymerization of long-chain branched components. Specifically, if the temperature difference between the most upstream and most downstream addition points of the reaction initiator addition points in an autoclave reactor or a tubular reactor, relative to the direction of continuous polymerization progression, is 15°C or more and 40°C or less, and if the temperature of the most upstream addition point is 215°C or more and 280°C or less, low-density polyethylene with a non-uniform degree of polymerization of long-chain branched components tends to be produced in a stable state from the viewpoint of safety and disaster prevention. Furthermore, for example, when a large amount of polymer is present at the most upstream reaction initiation point, the probability that the reaction initiator will come into contact with the polymer increases, and long-chain branches tend to be more likely to be formed in an upstream stage in the polymerization reactor. When long-chain branches are formed upstream in the reactor, the reaction initiator comes into contact with the long-chain branched structures at subsequent reaction initiation points, resulting in the formation of low-density polyethylene having a hyperbranched structure in which long-chain branches are further formed on the long-chain branched structures. Specifically, at the reaction initiator addition point in an autoclave reactor or a tubular reactor, if the conversion rate at the most upstream addition point with respect to the direction of progression of continuous polymerization is 10% or more, low-density polyethylene having a hyperbranched structure tends to be formed.

[0037] The high-density polyethylene contained in the polyethylene composition of this embodiment preferably has a polymer structure that has low molecular mobility in the temperature range in which the low-density polyethylene component crystallizes and that can inhibit the crystallization of the low-density polyethylene. For example, components with high molecular weights or high-density polyethylene with little entanglement are not incorporated into crystals, and polymer chains that can move freely are unlikely to be generated, resulting in low molecular mobility and easily inhibiting the crystallization of the low-density polyethylene. By containing such high-density polyethylene, ΔH S1 / ΔH S2 The value of can be controlled within the above-mentioned range. Furthermore, the molecular mobility can be evaluated by pulse NMR, which will be described later.

[0038] The method for producing the above-mentioned high-density polyethylene is not particularly limited, but examples include methods of adjusting the type of polymerization catalyst, preparation method, polymerization temperature, polymerization pressure, and reaction conditions. For example, when preparing the polymerization catalyst, the catalyst concentration supported on the catalyst support is reduced and adjusted so that the support points are not crowded together, thereby increasing the distance between the starting points of polymer growth and tending to reduce entanglement at the time of polymer growth. Specifically, by adjusting the ratio of the molar concentration of titanium, which is the active site, to the molar concentration of magnesium atoms contained in the support in the reaction solution to 0.005 or more and 0.150 or less, the support points are not crowded together and the starting points of polymer growth are increased in distance, tending to produce high-density polyethylene with fewer entanglements and less free-moving polymer chains.

[0039] The polyethylene composition of the present embodiment is not particularly limited, and can be produced, for example, by melt-kneading high-density polyethylene and a high-pressure low-density polyethylene resin. Examples of melt-kneaders that can be used in the kneading process include single-screw extruders, twin-screw extruders, vent extruders, and tandem extruders. Melt-kneading using these extruders is particularly preferred because the polyethylene raw material is mixed uniformly at the molecular level in the molten state, i.e., mixed without decomposing the polymer chains, which tends to promote the phenomenon of inhibiting crystallization described above. To achieve molecular-level mixing in the molten state, it is effective to appropriately adjust the extrusion conditions, such as the extruder's screw rotation speed, screw configuration, and extrusion temperature. Specifically, setting the extrusion temperature to 230°C or higher and 300°C or lower is preferred because it prevents polymer chain decomposition and promotes active molecular motion, which tends to result in the low-density polyethylene and high-density polyethylene being mixed at the molecular level. Furthermore, the method for ensuring the productivity of the polyethylene composition while mixing the polyethylene raw material at the molecular level in these extruders is not particularly limited, but for example, it is effective to generate an appropriate amount of backflow (a phenomenon in which the resin flows backward without passing through a screen) at the outlet at the tip of the screw of the extruder. The degree of backflow depends on the extrusion rate (kg / h), the area through which the resin passes (cm 2), and resin pressure (MPa). Backflow is likely to occur when the extrusion rate is high and the area through which the resin passes is small, or when the resin pressure is high, and by creating a moderate backflow, dispersion tends to improve. Specifically, in a single-screw extruder, the ratio of the extrusion rate to the area through which the resin passes (extrusion rate (kg / h) / area through which the resin passes (cm 2 ) is preferably adjusted to 1.0 or more and 10.0 or less, and the resin pressure is adjusted to 5.0 MPa or more and 20.0 MPa or less, because this causes an appropriate backflow and promotes dispersion of the high-density polyethylene and the low-density polyethylene.

[0040] (The heat of fusion obtained by differential scanning calorimetry (DSC), ΔH T1 , ΔH S1 / ΔH T1 ) As shown in the above <Condition (D)>, the polyethylene composition of the present embodiment is subjected to the pretreatment described in the following [Pretreatment Condition (T)], and then the heat of fusion calculated from the temperature-heat flow curve obtained by the first scan of differential scanning calorimetry (DSC) measured within 24 hours thereafter is ΔH T1 When this is the case, ΔH T1 The value of ΔH is 110 J / g or more and 240 J / g or less, S1 The ratio of ΔH S1 / ΔH T1 The value of is between 1.000 and 1.100. [Pretreatment conditions (T)] According to JIS K7210 Code D:1999, the wire is processed into a strand at 190°C under a load of 2.16 kg, annealed at 100°C for 1 hour, and then air-cooled in a standard atmosphere at a temperature of 21°C to 25°C for 1 hour.

[0041] ΔH T1 is preferably 120 J / g or more, more preferably 130 J / g or more, and is preferably 230 J / g or less, more preferably 220 J / g or less, and even more preferably 200 J / g or less. ΔH T1 When the value of is within the above range, the heat resistance and processability when laminated tend to be excellent.

[0042] Also, ΔH S1 / ΔH T1 is preferably 1.008 or more, more preferably 1.015 or more, and is preferably 1.090 or less, more preferably 1.080 or less, even more preferably 1.060 or less, and even more preferably 1.050 or less. ΔH S1 / ΔH T1 If the value is 1.000 or more, the adhesiveness to the substrate improves during lamination processing, and furthermore, breakage and thickness unevenness during thin film processing tend to be reduced. S1 / ΔH T1 When the value is 1.100 or less, the heat resistance of the molded product tends to improve. S1 / ΔH T1 When the value of is within the above range, the balance between adhesion to the substrate and heat resistance when laminated tends to be excellent, and therefore the heat pinhole resistance tends to be improved.

[0043] The pretreatment method and DSC measurement method applied to the measurement of the polyethylene composition of the present embodiment are not particularly limited, and can be carried out, for example, by the methods described in the Examples.

[0044] ΔH T1 is the heat of fusion measured by DSC after carrying out [pretreatment condition T], which is an operation of carrying out annealing at 100°C and then air-cooling. This operation allows the high-density polyethylene component and the low-density polyethylene component contained in the polyethylene composition to be crystallized.

[0045] The polyethylene composition of the present embodiment has a ΔH S1 , ΔH T1 ΔH is the ratio of S1 / ΔH T1 The value of is between 1.000 and 1.100, which is the ΔH T1 The value of ΔH S1 This indicates that the value is smaller than the value of . The following can be considered as the reason for this phenomenon.

[0046] ΔH T1 The value of ΔH is the heat of fusion measured by performing annealing only at 100°C. At this time, the high-density polyethylene component and the low-density polyethylene component contained in the polyethylene composition are each crystallized. Here, if the molecular mobility of the high-density polyethylene component at 100°C is low, the crystallization of the high-density polyethylene component does not proceed sufficiently. On the other hand, ΔH S1 The value is the heat of fusion measured after annealing at 120°C, air cooling, and then annealing at 100°C. Therefore, it is thought that crystallization of high-density polyethylene proceeds at 120°C, where molecular motion is more active. That is, ΔH T1 The lower the molecular mobility of high density polyethylene at 100°C, the smaller the value of ΔH S1 The value of is the heat of fusion of each component in the crystallized state. S1 / ΔH T1 The value of ΔH is considered to indicate the degree of molecular mobility of the high-density polyethylene component contained in the polyethylene composition. S1 / ΔH T1 When the value of ΔH is 1.000 or more, the molecular mobility of the high-density polyethylene is low and ΔH T1 The value of ΔH S1 This indicates that the value is smaller than

[0047] Polyethylene compositions containing a high-density polyethylene component with low molecular mobility at 100°C tend to improve adhesion to paper and improve heat pinhole resistance in thin films by inhibiting crystallization of the low-density polyethylene component during the cooling process of melt lamination onto paper. Furthermore, inhibiting crystallization extends the stress relaxation time, which tends to stabilize film-forming processability and suppress breakage during high-speed film formation.

[0048] ΔH S1 / ΔH T1Examples of methods for controlling the value include a method in which the polymer structures of the high-density polyethylene and the low-density polyethylene contained in the polyethylene composition are precisely controlled, and the molecular mobility at each temperature is appropriately controlled, and then the polyethylene composition is produced using an appropriate composition ratio and mixing method.

[0049] The high-density polyethylene contained in the polyethylene composition of this embodiment preferably has a polymer structure that has low molecular mobility in the temperature range in which the low-density polyethylene component crystallizes and that can inhibit the crystallization of the low-density polyethylene. For example, components with high molecular weights or high-density polyethylene with little entanglement are not incorporated into crystals, and polymer chains that can move freely are unlikely to be generated, resulting in low molecular mobility and easily inhibiting the crystallization of the low-density polyethylene. By containing such high-density polyethylene, ΔH S1 / ΔH T1 The value of can be controlled within the above-mentioned range. Furthermore, the molecular mobility can be evaluated by pulse NMR, which will be described later.

[0050] Methods for producing such high-density polyethylene are not particularly limited, but include adjusting the type of polymerization catalyst, preparation method, polymerization temperature, polymerization pressure, and reaction conditions. For example, when preparing the polymerization catalyst, the catalyst concentration supported on the catalyst support is reduced and adjusted so that the support points are not crowded together, thereby increasing the distance between the starting points of polymer growth and tending to reduce entanglement at the time of polymer growth. Specifically, by adjusting the ratio of the molar concentration of titanium, which is the active site, to the molar concentration of magnesium atoms contained in the support in the reaction solution to 0.005 or more and 0.150 or less, the support points are not crowded together and the starting points of polymer growth are increased in distance, tending to produce high-density polyethylene with fewer entanglements and less free-moving polymer chains.

[0051] (Composition and composition ratio of polyethylene composition) From the viewpoint of reducing FE and achieving an excellent balance between heat resistance and processability, the polyethylene composition of the present embodiment has a density of 942 kg / m as shown in the above <Condition (E)>. 3 High density polyethylene (A) or higher and a density of 930 kg / m 3 The following low density polyethylenes (B) are preferred: The composition ratio is preferably 10% to 90% high-density polyethylene and 10% to 90% low-density polyethylene, more preferably 20% to 80% high-density polyethylene and 20% to 80% low-density polyethylene. The types of high density polyethylene and low density polyethylene are not particularly limited, and they may be one type of each or a multi-component system in which several types are mixed.

[0052] (Pulse NMR measurement of low-density polyethylene (B) at 120°C, relaxation time of high-mobility components, and proportion of high-mobility components) As shown in the above <Condition (E)>, the polyethylene composition of the present embodiment is a polyethylene composition having a density of 930 kg / m 3 When the free induction decay curve of the following low-density polyethylene (B) is measured by pulse NMR at 120°C using the Carr Purcell Meiboom Gill (hereinafter sometimes referred to as CPMG) method and approximated as a three-component curve, it is preferable that the relaxation time Tγ of the high mobility component γ is 100 ms or more and 200 ms or less, and the abundance ratio Rγ of the high mobility component γ is 9% or more and 24% or less. The abundance ratio Rγ of the high mobility component γ in the low density polyethylene (B) is more preferably 11% or more, and even more preferably 13% or more, and more preferably 22% or less, and even more preferably 20% or less. The relaxation time Tγ of the high mobility component γ in the low-density polyethylene (B) is more preferably 110 ms or more, and even more preferably 120 ms or more, and more preferably 190 ms or less, and even more preferably 180 ms or less.

[0053] In pulse NMR of the low-density polyethylene (B) contained in the polyethylene composition of the present embodiment at 120°C, when the free induction decay curve obtained by the CPMG method is approximated as a three-component curve, the high-mobility component γ is a component that can move freely without being constrained at 120°C. It is believed that low-density polyethylenes containing a large amount of such components tend to inhibit the crystallization of high-density polyethylene when it crystallizes from a molten state. Therefore, when the abundance ratio Rγ of the high-mobility component γ in the low-density polyethylene (B) is 9% or more, the crystallization of the high-density polyethylene (A) tends to be inhibited. This inhibits crystallization during the cooling process of melt lamination onto paper, which tends to improve adhesion to paper and improve heat pinhole resistance in thin films. Furthermore, the inhibition of crystallization extends the stress relaxation time, which stabilizes film-forming processability and tends to suppress breakage during high-speed film formation. It is preferable that the abundance ratio Rγ of the high mobility component γ in the low-density polyethylene (B) is 24% or less, since the strength and heat resistance of a film using the polyethylene composition of the present embodiment are improved.

[0054] The relaxation time Tγ of the highly mobile component γ is an index showing the degree of constraint of the molecular chain of the highly mobile component γ. The shorter the relaxation time in pulse NMR measurement, the more constrained the molecular chains are. A relaxation time Tγ of the highly mobile component γ of the low-density polyethylene (B) of 100 ms or more is preferred because the molecular mobility is high and the crystallization of the high-density polyethylene (A) can be sufficiently inhibited. A relaxation time Tγ of 200 ms or less is preferred because the melt tension increases due to the constrained molecular chains, improving the film formation stability.

[0055] In the polyethylene composition of the present embodiment, the proportion Rγ of high mobility components γ and the relaxation time Tγ at 120°C of the low-density polyethylene (B) can be controlled within the above-mentioned ranges by adjusting the polymerization conditions, such as the polymerization temperature, polymerization pressure, type of polymerization initiator, and type of chain transfer agent, and thereby controlling the amount of long-chain branches. Specifically, methods that do not use a chain transfer agent or methods that produce low-density polyethylene under forced stirring conditions tend to make it easier for radical polymerization initiation sites to occur, resulting in a large number of long-chain branches and a high proportion Rγ of high mobility components γ. More specifically, using an autoclave-type reactor, adjusting the polymerization pressure to within 120 to 200 MPa, and adjusting the average temperature of the polymerization reactor to within the range of 220 to 300°C is preferred, as this tends to activate the long-chain branch formation reaction.

[0056] Furthermore, for example, if the degree of polymerization at the start of polymerization is high and multiple reaction initiation points are provided in a polymerization reactor with a temperature difference between the most upstream and most downstream points, polymers with different degrees of polymerization will be produced at each reaction initiation point, and these will be incorporated as long-chain branched structures, tending to produce a low-density polyethylene (B) with a non-uniform degree of polymerization of the long-chain branched component γ. Such low-density polyethylene (B) exhibits complex molecular motion, and therefore tends to have an increased abundance ratio Rγ of the highly mobile component γ and an increased relaxation time Tγ. Specifically, if the temperature difference between the most upstream and most downstream addition points of the initiator addition points in an autoclave reactor or tubular reactor relative to the direction of continuous polymerization progression is 15°C or more and 40°C or less, and if the temperature of the most upstream addition point is 215°C or more and 280°C or less, a low-density polyethylene (B) with a non-uniform degree of polymerization of the long-chain branched component tends to be produced in a stable state from the viewpoint of safety and disaster prevention. Furthermore, for example, when a large amount of polymer is present at the most upstream reaction initiation point, a long-chain branching reaction occurs in the upstream stage of the polymerization reactor. If long-chain branches are formed upstream in the reactor, the reaction initiator comes into contact with the long-chain branched structures at subsequent reaction initiation points, resulting in the formation of a hyperbranched low-density polyethylene (B) in which further long-chain branched structures are formed on the long-chain branched structures. Specifically, in an autoclave reactor or tubular reactor, if the conversion rate at the most upstream initiator addition point relative to the direction of continuous polymerization is 10% or higher, a hyperbranched low-density polyethylene is formed. Such low-density polyethylene (B) exhibits complex molecular motion, and therefore tends to have an increased abundance ratio Rγ of the highly mobile component γ and a relaxation time Tγ.

[0057] Specifically, pulse NMR measurement applied to the measurement of the low-density polyethylene (B) contained in the polyethylene composition of the present embodiment is carried out by the following method. First, a sample tube filled with low-density polyethylene (B) up to a height of 1 cm from the bottom is placed in a Bruker TD-NMR apparatus (model: minispec mq20) set to an internal temperature of 30°C, and the sample tube is heated according to the heating conditions shown below. The temperatures shown in the following <Heating Conditions> are values ​​obtained by measuring the internal temperature of the sample with a thermocouple. <Temperature increase conditions> (1) Set the temperature to 30°C and let it stand for 5 minutes. (2) The temperature is increased to 120°C at a rate of 5°C / min. (3) After heating to 120°C, let stand for 25 minutes. After the temperature increase is completed by the above-mentioned procedure, the spin-spin relaxation time (T2, sometimes simply referred to as "relaxation time T" in this specification) of polyethylene is measured according to the <measurement conditions> shown below. <Measurement conditions> Magnetic field strength: 0.47T Measured nuclides: 1 H(20MHz) Measurement method: Carr Purcell Meiboom Gill method Number of times accumulated: 256 Repeat time: 3 seconds The free induction decay (FID) obtained by the above measurement is subjected to curve fitting using the analysis program TD-NMR-A manufactured by Bruker. For fitting, the function shown in the following <Equation 1> is used. <Expression 1> f(t)=Rαexp(-t / Tα)+Rβexp(-t / Tβ)+Rγexp(-t / Tγ) (However, Rα+Rβ+Rγ=100) t: variable (time elapsed since pulse irradiation) Tα: Relaxation time of the low-mobility component α (ms) Rα: Presence rate of low-motile component α (%) Tβ: Relaxation time of intermediate component β (ms) Rβ: Abundance ratio of intermediate component β (%) Tγ: Relaxation time of the high-mobility component γ (ms) Rγ: Percentage of the presence of highly mobile component γ (%)

[0058] Generally, in the case of a polymer in a rubbery state where the molecular chain movement is active, the free induction decay obtained by pulsed NMR measurement can be represented by an exponential function. Therefore, in this measurement as well, the obtained free induction decay can be fitted as the sum of three different components represented by an exponential function as shown in the above <Equation 1>. Also, the decay rate of the free induction decay 1 It is known that the higher the mobility of H, that is, the higher the mobility of the molecular chain, the slower it becomes. Since the relaxation times T in each exponential function are in the relationship of Tα < Tβ < Tγ, the component with the lowest mobility is α, the component with intermediate mobility is β, and the component with the highest mobility is γ. Furthermore, component α corresponds to the part where the molecular chains are strongly intertwined in polyethylene, component β corresponds to the part where the molecular chains are weakly intertwined, and component γ corresponds to the part where the molecular chains are not intertwined. The pulsed NMR measurement at 120°C in this embodiment can be more specifically measured by the method described in the examples.[[ID=第十三条]]

[0059] (Pulsed NMR measurement of high-density polyethylene (A) at 100°C, percentage of the presence of low-mobility component, percentage of the presence of high-mobility component) The polyethylene composition of this embodiment is, as shown in the above <Condition (G)>, the high-density polyethylene (A) with a density of 942 kg / m 3 or more contained in the polyethylene composition, when the free induction decay curve obtained by the Solid Echo (hereinafter sometimes referred to as SE) method in the pulsed NMR measurement at 100°C is approximated by three components, it is preferable that the percentage of the presence of the low-mobility component α, Rα, is 55% or more and 85% or less, and the percentage of the presence of the high-mobility component γ, Rγ, is 1% or more and 10% or less. The percentage of the presence of the low-mobility component α, Rα, in the high-density polyethylene (A) is more preferably 58% or more, and even more preferably 60% or more. Also, it is more preferably 83% or less, and even more preferably 80% or less. The abundance ratio Rγ of the high mobility component γ in the high density polyethylene (A) is more preferably 2% or more, and even more preferably 3% or more, and more preferably 9% or less, and even more preferably 8% or less.

[0060] In pulse NMR at 100°C of the high-density polyethylene (A) contained in the polyethylene composition of the present embodiment, when the free induction decay curve obtained by the SE method is approximated into three components, the low-mobility component α is a component that is constrained to crystals at 100°C, and the high-mobility component γ is a component that is not constrained and can move freely at 100°C. High-density polyethylene (A) containing a large amount of low-mobility component α and a small amount of high-mobility component γ tends to inhibit the crystallization of low-density polyethylene (B) due to its low molecular mobility. Therefore, when the proportion of low-mobility component α (Rα) in high-density polyethylene (A) is 55% or more and the proportion of high-mobility component γ (Rγ) is 10% or less, crystallization of low-density polyethylene (B) tends to be inhibited. This inhibits crystallization during the cooling process of melt lamination onto paper, which tends to improve adhesion to paper and improve heat pinhole resistance in thin films. Furthermore, the inhibition of crystallization extends the stress relaxation time, which stabilizes film formation processability and tends to suppress breakage and thickness unevenness during high-speed film formation. In the high-density polyethylene (A), when the abundance ratio Rα of the low-mobility component α is 85% or less and the abundance ratio Rγ of the high-mobility component γ is 1% or more, the compatibility between the low-density component and the high-density component is improved, which tends to suppress a decrease in strength and uneven appearance of the polyethylene composition of the present embodiment.

[0061] Methods for controlling the abundance ratio Rα of the low mobility component α and the abundance ratio Rγ of the high mobility component γ at 100°C in the high-density polyethylene (A) contained in the polyethylene composition of this embodiment within the above-mentioned numerical ranges are not particularly limited, and include adjusting the type of polymerization catalyst, the polymerization catalyst preparation method, the polymerization temperature, the polymerization pressure, and the reaction conditions. For example, when preparing the polymerization catalyst, reducing the amount of catalyst loaded per support particle and adjusting the loading points so that they are not crowded together results in the initiation points of polymer growth being spaced apart, which tends to reduce entanglement during polymer growth. Specifically, from the viewpoint of increasing and complicating the particle radius of the catalyst support, reducing the loading amount per support particle, and reducing entanglement during polymer growth, a preferred method is to simultaneously charge the raw materials, an organomagnesium compound, and a chlorinating agent during catalyst support synthesis and react them without stirring. Furthermore, in the step of supporting active sites on a support, by adjusting the ratio of the molar concentration of titanium (active sites) to the molar concentration of magnesium atoms contained in the support in the reaction solution (molar concentration of titanium / molar concentration of magnesium atoms) to 0.01 or more and 0.15 or less, the support sites are not densely packed and the distance between the starting points of polymer growth is increased, resulting in the production of a high-density polyethylene (A) with fewer entangled structures and less free-moving polymer chains. Since such high-density polyethylene (A) is less likely to produce free-moving polymer chains, the abundance ratio Rα of low-mobility components α tends to be high and the abundance ratio Rγ of high-mobility components γ tends to be low.

[0062] Specifically, pulse NMR measurement applied to the measurement of the high-density polyethylene (A) contained in the polyethylene composition of the present embodiment is carried out by the following method. First, a sample tube filled with high-density polyethylene (A) up to a height of 1 cm from the bottom is placed in a Bruker TD-NMR apparatus (model: minispec mq20) set to an internal temperature of 30°C, and the sample tube is heated according to the heating conditions shown below. The temperatures shown in the following <Heating Conditions> are values ​​obtained by measuring the internal temperature of the sample with a thermocouple. <Temperature increase conditions> (1) Set the temperature to 30°C and let it stand for 5 minutes. (2) The temperature is increased to 100°C at a rate of 5°C / min. (3) After heating to 100°C, let stand for 25 minutes. After the temperature increase is completed by the above-mentioned procedure, the spin-spin relaxation time (T2, sometimes simply referred to as "relaxation time T" in this specification) of polyethylene is measured according to the <measurement conditions> shown below. <Measurement conditions> Magnetic field strength: 0.47T Measured nuclides: 1 H(20MHz) Measurement method: Solid Echo method Number of times accumulated: 256 Repeat time: 3 seconds The free induction decay (FID) obtained by the above measurement is subjected to curve fitting using the analysis program TD-NMR-A manufactured by Bruker. For fitting, the function shown in the following <Equation 1> is used. <Expression 1> f(t)=Rαexp(-t / Tα)+Rβexp(-t / Tβ)+Rγexp(-t / Tγ) (However, Rα+Rβ+Rγ=100) t: variable (time elapsed since pulse irradiation) Tα: Relaxation time of the low-mobility component α (ms) Rα: Presence rate of low-motile component α (%) Tβ: Relaxation time of intermediate component β (ms) Rβ: Abundance ratio of intermediate component β (%) Tγ: Relaxation time of the high-mobility component γ (ms) Rγ: The proportion of highly mobile component γ (%)

[0063] Generally, for polymers in a rubbery state where molecular chain motion is active, the free induction decay obtained by pulsed NMR measurements can be expressed by an exponential function. Therefore, in this measurement, the free induction decay obtained can also be fitted as the sum of three different components expressed by exponential functions, as shown in the above <Equation 1>. The decay rate of free induction decay is1 It is known that the higher the mobility of H, that is, the higher the mobility of the molecular chain, the slower it becomes. Since the relaxation time T in each exponential function has the relationship of Tα < Tβ < Tγ, the component with the lowest mobility is designated as α, the component with intermediate mobility as β, and the component with the highest mobility as γ. Furthermore, component α corresponds to the part where the molecular chains are strongly intertwined in polyethylene, component β corresponds to the part where the molecular chains are weakly intertwined, and component γ corresponds to the part where the molecular chains are not intertwined. The pulse NMR measurement at 100 °C in this embodiment can be more specifically measured by the method described in the examples.

[0064] 〔Molded body〕 The molded body of this embodiment is a molded body of the polyethylene composition of this embodiment described above, and examples include a film-shaped molded body and a laminate. When the molded body of this embodiment has a multilayer structure, the polyethylene composition of this embodiment described above may be used in the outermost layer or the intermediate layer. Specific uses of the film include surface protection films for optical members and the like, and specific uses of the laminate include, for example, moisture-proof paper, release paper, and medical packaging materials.

[0065] 〔Method for producing polyethylene composition〕 The method for producing the polyethylene composition of this embodiment is not particularly limited, and examples include a method of containing high-density and low-density components by connecting a plurality of polymerization reactors, and a method of separately producing and mixing high-density and low-density components. In particular, a method of pre-mixing high-density polyethylene (A) and low-density polyethylene (B) produced by the high-pressure method and melt-kneading is preferred. <​​​​​​​​The method for pre-mixing the high-density polyethylene (A) and the low-density polyethylene (B) is not particularly limited, but examples include a method in which the high-density polyethylene (A) and the low-density polyethylene (B) are pre-pelletized, respectively, and the pellets are dry-blended.

[0067] Examples of melt kneaders that can be used in the kneading operation include single-screw extruders, twin-screw extruders, vent extruders, and tandem extruders. In particular, a method of melt kneading a high-density polyethylene (A) and a low-density polyethylene (B) that have been dry-blended in advance using a single-screw extruder or twin-screw extruder is preferred from the viewpoints of productivity and uniform dispersion. Furthermore, setting the extrusion temperature to 230°C or higher and 300°C or lower is preferred because it prevents decomposition of polymer chains and promotes active molecular motion, which tends to result in mixing of the low-density polyethylene (B) and the high-density polyethylene (A) at the molecular level.

[0068] Furthermore, methods for ensuring the productivity of the polyethylene composition while mixing the polyethylene raw materials at a molecular level in these extruders include a method in which the low-density polyethylene and the high-density polyethylene are mixed at a molecular level by generating an appropriate backflow (a phenomenon in which the resin flows backward without passing through a screen) at the outlet at the tip of the screw of the extruder. The degree of backflow depends on the extrusion rate (kg / h), the resin flow area (cm 2 ), and resin pressure (MPa). Backflow is likely to occur when the extrusion rate is high and the area through which the resin passes is small, or when the resin pressure is high, and by creating a moderate backflow, dispersion tends to improve. Specifically, in a single-screw extruder, the ratio of the extrusion rate to the area through which the resin passes (kg / h·cm 2 It is preferable to adjust the viscosity (V) to 2.0 or more and 10.0 or less and the resin pressure to 3.0 MPa or more and 20.0 MPa or less, because this causes a moderate backflow and promotes dispersion of the high-density polyethylene (A) and the low-density polyethylene (B). The resin passage area here is expressed as the product of the extruder cylinder diameter and the porosity of the screen mesh.

[0069] The high-density polyethylene (A) can be produced, for example, by a continuous slurry polymerization method. The catalyst used in the production is not particularly limited, and examples thereof include a metallocene catalyst, a Ziegler-Natta catalyst, and a Phillips catalyst.

[0070] The Ziegler-Natta catalyst used in the production of the high-density polyethylene (A) is not particularly limited, but an olefin polymerization catalyst produced by supporting an organomagnesium compound and a titanium compound on a support prepared by reacting an organomagnesium compound with a chlorinating agent is preferred.

[0071] The organomagnesium compound used in the catalyst carrier is shown in the form of an organomagnesium complex compound soluble in an inert hydrocarbon solvent, and includes all dihydrocarbylmagnesium compounds and complexes of these compounds with other metal compounds. The chlorinating agent used in the catalyst carrier is a silicon chloride compound having at least one Si-H bond.

[0072] The method for reacting the organomagnesium compound and the chlorinating agent in preparing the carrier is not particularly limited, and either a simultaneous addition method in which they are simultaneously introduced into a reactor and reacted, or a method in which one is first introduced into a reactor and then the other is introduced into the reactor, can be used. In particular, from the viewpoints of increasing and complicating the particle radius of the catalyst carrier, reducing the amount supported on one carrier particle, and reducing entanglement during polymer growth, a method in which the organomagnesium compound and the chlorinating agent are simultaneously charged and reacted without stirring is preferred.

[0073] The amount of titanium compound used to serve as the active site of the olefin polymerization catalyst is not particularly limited. However, from the viewpoint of reducing the amount loaded per support particle and reducing entanglement during polymer growth, in the step of loading the active sites onto the support, the ratio of the molar concentration of titanium serving as the active site to the molar concentration of magnesium atoms contained in the support in the reaction solution is preferably 0.01 or more and 0.15 or less, more preferably 0.02 or more and 0.14 or less.

[0074] In general, physical properties such as molecular weight and density of polyethylene can be controlled by adjusting the polymerization temperature, polymerization pressure, comonomer concentration, and hydrogen concentration in addition to the catalyst type.

[0075] The comonomer that can be used in the production method of the high-density polyethylene (A) of the present embodiment is not particularly limited, and examples thereof include compounds selected from the group consisting of propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, vinylcyclohexane, styrene, and derivatives thereof; cyclopentene, cyclohex ... Examples of the cyclic olefin include a cyclic olefin having 3 to 20 carbon atoms selected from the group consisting of cycloheptene, norbornene, 5-methyl-2-norbornene, tetracyclododecene, and 2-methyl-1,4,5,8-dimethano-1,2,3,4,4a,5,8,8a-octahydronaphthalene; and a linear, branched, or cyclic diene having 4 to 20 carbon atoms selected from the group consisting of 1,3-butadiene, 1,4-pentadiene, 1,5-hexadiene, 1,4-hexadiene, 1,7-octadiene, and cyclohexadiene. In particular, propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, and the like are preferred, and the density of the high-density polyethylene (A) can be adjusted by appropriately controlling the type and concentration of the comonomer.

[0076] The polymerization temperature in the production method of the high-density polyethylene (A) is preferably 30° C. or higher and 100° C. or lower. A polymerization temperature of 30° C. or higher enables industrially more efficient production, while a polymerization temperature of 100° C. or lower enables continuous and more stable operation.

[0077] The solvent used in the continuous slurry polymerization method can be an inert hydrocarbon medium, and the olefin itself can also be used as the solvent. Examples of the inert hydrocarbon medium include, but are not limited to, aliphatic hydrocarbons such as propane, butane, isobutane, pentane, isopentane, hexane, heptane, octane, decane, dodecane, and kerosene; alicyclic hydrocarbons such as cyclopentane, cyclohexane, and methylcyclopentane; aromatic hydrocarbons such as benzene, toluene, and xylene; halogenated hydrocarbons such as ethyl chloride, chlorobenzene, and dichloromethane; and mixtures thereof.

[0078] The polymerization pressure in the production method of the high-density polyethylene (A) is usually preferably from atmospheric pressure to 2 MPa, more preferably from 0.1 MPa to 1.5 MPa, and even more preferably from 0.1 MPa to 1.0 MPa.

[0079] The molecular weight of the high-density polyethylene (A) used in the polyethylene composition of the present embodiment can be adjusted by making hydrogen present in the polymerization system or by changing the polymerization temperature, as described in German Patent Application Publication No. 3127133. The molecular weight can be controlled within an appropriate range by adding hydrogen as a chain transfer agent to the polymerization system. The solvent separation method may be decantation, centrifugation, or filtration, but centrifugation is more preferred because it provides a good separation efficiency for the ethylene polymer and the solvent. The polymer powder is granulated into pellets using a single-screw extruder, twin-screw extruder, vent extruder, tandem extruder, etc. The type of extruder and the number of extrusions are not particularly limited, but kneading using a twin-screw extruder is preferred.

[0080] The low-density polyethylene (B) used in the polyethylene composition of the present embodiment can be obtained by radical polymerization of ethylene in, for example, an autoclave-type or tubular-type reactor, although this is not limited thereto. In particular, the method of polymerization in an autoclave type reactor is preferred because the reaction of forming long chain branches is promoted by forced stirring. The molecular weight, density, molecular weight distribution, and molecular structure of the resulting low-density polyethylene (B) are controlled by the polymerization temperature, polymerization pressure, type of peroxide, and the presence or absence of a chain transfer agent. Generally, setting the polymerization pressure high tends to increase the molecular weight, while setting the polymerization pressure low tends to decrease the molecular weight. Furthermore, adding a chain transfer agent can suppress the branching reaction, which tends to increase the density and decrease the molecular weight.

[0081] In the production method for the low-density polyethylene (B), when an autoclave-type reactor is used, the polymerization temperature and polymerization pressure may be set to a temperature of 200 to 300°C and a polymerization pressure of 100 to 250 MPa in the presence of peroxide, while when a tubular-type reactor is used, the polymerization reaction peak temperature may be set to a temperature of 180 to 400°C and a polymerization pressure of 100 to 400 MPa in the presence of peroxide. In particular, using an autoclave-type reactor, adjusting the polymerization pressure to within 120 to 200 MPa, and adjusting the average temperature of the polymerization reactor to within the range of 220 to 300°C is preferred, as this tends to activate the long-chain branch formation reaction.

[0082] Examples of peroxides used in the production method of the low-density polyethylene (B) include, but are not limited to, methyl ethyl ketone peroxide, peroxyketals (specifically, 1,1-bis(t-butylperoxy)3,3,5-trimethylcyclohexane, 1,1-bis(t-butylperoxy)cyclohexane, 2,2-bis(t-butylperoxy)octane, n-butyl 4,4-bis(t-butylperoxy)valerate, 2,2-bis(t-butylperoxy)butane, etc.), hydroperoxides (specifically, Specifically, these include t-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, p-menthane hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, etc.), dialkyl peroxides (specifically, di-t-butyl peroxide, dicumyl peroxide, bis(t-butylperoxyisopropyl)benzene, t-butylcumyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, 2,5-di methyldi(t-butylperoxy)hexane-3, etc.), diacyl peroxides (specifically, acetyl peroxide, isobutyryl peroxide, octanoyl peroxide, 3,5,5-trimethylhexanoyl peroxide, benzoyl peroxide, etc.), peroxydicarbonates (specifically, diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, di-n-propyl peroxydicarbonate, di-2-ethoxyethyl peroxydicarbonate, , dimethoxyisopropyl peroxydicarbonate, di(3-methyl-3-methoxybutyl peroxydicarbonate, diallyl peroxydicarbonate, etc.), peroxyesters (specifically, t-butyl peroxyacetate, t-butyl peroxyisobutyrate, t-butyl peroxypivalate, t-butyl peroxyoctate, t-butyl peroxyneodecanoate, cumyl peroxyneodecanoate, t-butyl peroxy-2-ethylhexanoate, t-butyl peroxy-3,5,6-trimethylhexanoate, t-butyl peroxylaurate, t-butyl peroxybenzoate, t-butyl peroxyisopropyl carbonate, cumyl peroxyoctoate, t-hexyl peroxyneodecanoate, t-hexyl peroxypivalate, t-butyl peroxyneohexanoate, t-hexyl peroxyneohexanoate, cumyl peroxyneohexanoate, etc.), acetylcyclohexylsulfonyl peroxide, t-butyl peroxyallyl carbonate, etc.

[0083] It is particularly preferable to select a highly reactive peroxide, for example, a peroxyester (specifically, t-butyl peroxyacetate, t-butyl peroxyisobutyrate, t-butyl peroxypivalate, t-butyl peroxyoctate, t-butyl peroxyneodecanoate, cumyl peroxyneodecanoate, t-butylperoxy-2-ethylhexanoate, t-butylperoxy-3,5,6-trimethylhexanoate, t-butyl peroxylaurate, t-butyl peroxybenzoate, t-butyl peroxyisopropyl carbonate, cumyl peroxyoctoate, t-hexyl peroxyneodecanoate, t-hexyl peroxypivalate, t-butyl peroxyneohexanoate, t-hexyl peroxyneohexanoate, cumyl peroxyneohexanoate, etc.), because this promotes the long-chain branch-forming reaction.

[0084] The method for adding the peroxide in the production method of the low-density polyethylene (B) is not particularly limited, but examples thereof include a method of adding the peroxide directly to a polymerization reactor, a method of adding the peroxide after mixing with ethylene gas, and a method of adding the peroxide after diluting it with an organic solvent. The addition point may be one point or a plurality of points in the direction of progression of continuous polymerization.

[0085] The temperature conditions at the point where the peroxide is added affect the long chain branching structure of the low density polyethylene (B). For example, when the temperature of the most upstream peroxide addition point relative to the direction of progression of continuous polymerization is low, a polymer with a low degree of polymerization tends to be produced upstream of the reactor, whereas when the temperature of the most upstream peroxide addition point is high, a polymer with a high degree of polymerization tends to be produced upstream of the reactor. Furthermore, for example, when the temperature of the most downstream peroxide addition point relative to the direction of progression of continuous polymerization is low, a polymer with a low degree of polymerization tends to be produced downstream of the reactor, whereas when the temperature of the most downstream peroxide addition point is high, a polymer with a high degree of polymerization tends to be produced downstream of the reactor. In this way, by controlling the temperature at the point where the peroxide is added, it is possible to produce polymers with different degrees of polymerization in the direction of progress of the continuous reaction. Therefore, by allowing the continuous polymerization to proceed under conditions where there is a difference in temperature between the most upstream and most downstream points where the peroxide is added, and by promoting the long-chain branching reaction, polymers with different degrees of polymerization are incorporated as long-chain branches, and a low-density polyethylene (B) with a non-uniform degree of polymerization of the long-chain branched components is produced. Such low-density polyethylene (B) exhibits complex molecular motion, and therefore tends to have an increased abundance ratio Rγ of the highly mobile component γ and an increased relaxation time Tγ. In particular, when the temperature difference between the most upstream peroxide addition point and the most downstream peroxide addition point in the direction of progression of continuous polymerization in an autoclave reactor or a tubular reactor is 15°C or more and 40°C or less, and when the temperature of the most upstream peroxide addition point is 215°C or more and 280°C or less, low-density polyethylene (B) having a non-uniform degree of polymerization of long-chain branched components tends to be produced in a stable state from the viewpoint of safety and disaster prevention, which is preferred.

[0086] The conversion rate in the production method of low-density polyethylene (B) is not particularly limited, but is generally 5% or more and 50% or less. The conversion rate varies depending on the shape of the polymerization reactor, the type of reaction initiator, and the temperature at the point where the reaction initiator is added. If the temperature at the point where the reaction initiator is added is high, if the molecular weight of the reaction initiator is low, or if the reaction is carried out under forced stirring, the initiation reaction and propagation reaction become more active, and the conversion rate tends to be higher.

[0087] The conversion rate can be calculated from the production rate of low-density polyethylene (B) relative to the flow rate of ethylene gas supplied to the polymerization reactor. The production rate of low-density polyethylene (B) is calculated from the mass of pellets produced per unit time or a heat balance equation. In particular, the calculation method using a heat balance equation makes it possible to calculate the conversion rate at each location inside the polymerization reactor. For example, the amount of ethylene gas consumed by the polymerization reaction, i.e., the amount of polymer produced, can be calculated from the temperature and flow rate of ethylene gas supplied to the reactor, the temperature of the reaction site, the specific enthalpy of ethylene gas, and the heat of polymerization reaction. Furthermore, the conversion rate at each point in the reactor affects the long-chain branching structure of the low-density polyethylene (B). For example, if the conversion rate is high at the most upstream reaction initiation point and a large amount of polymer is present, long-chain branches tend to be formed in large quantities in the upstream stages of the polymerization reactor. If long-chain branches are formed upstream in the reactor, the reaction initiator comes into contact with the long-chain branching structures at subsequent reaction initiation points, resulting in the formation of low-density polyethylene (B) having a hyperbranched structure in which further long-chain branches are formed on the long-chain branching structures. Specifically, a conversion rate of 10% or more at the most upstream reaction initiator addition point in the direction of continuous polymerization progression is preferred because it produces low-density polyethylene (B) having a hyperbranched structure.

[0088] The chain transfer agent is not particularly limited, but for example, a hydrocarbon compound such as propane, propylene, or butane can be used, and various physical properties can be adjusted by terminating the radicals of the growing polymer. In particular, polymerization without using a chain transfer agent is preferred because it produces a polymer with a higher degree of polymerization and many long-chain branches.

[0089] (additives) The polyethylene composition of the present embodiment, each of the raw material components, and the molded article may further contain additives such as an antioxidant, a light stabilizer, a slip agent, a filler, and an antistatic agent. [Example]

[0090] The present embodiment will be described in detail below with reference to specific examples and comparative examples, but the present invention is not limited to the following examples and comparative examples. The measurement and evaluation methods for each physical property and characteristic are described below.

[0091] [Methods for measuring physical properties] (Physical Property 1) Melt flow rate (MFR) at 190°C and a load of 2.16 kg The melt flow rates (g / 10 min) of the polyethylene compositions obtained in the Examples and Comparative Examples, and the high-density polyethylene (A) and low-density polyethylene (B) used as raw materials were measured according to JIS K7210 Code D:1999 (temperature = 190°C, load = 2.16 kg).

[0092] ((Property 2) Density) The density (kg / m) of each polyethylene composition obtained in the examples and comparative examples, and the high-density polyethylene (A) and low-density polyethylene (B) used as raw materials was measured by the density gradient tube method (23°C) according to JIS K7112:1999. 3 ) was measured.

[0093] (Physical Property 3) Heat of fusion ΔH S1 , ΔH S2 ) Each of the polyethylene compositions obtained in the examples and comparative examples was subjected to differential scanning calorimetry (DSC) using a PerkinElmer DSC-7 differential scanning calorimeter, and a DSC curve (temperature-heat flow curve) was obtained according to the following procedures and conditions. (1) As a pretreatment, in accordance with JIS K7210 Code D:1999, the wire was processed into a strand at 190°C under a load of 2.16 kg, annealed at 120°C for 1 hour, and then air-cooled for 1 hour in a standard atmosphere at a temperature of 21°C to 25°C. Subsequently, the wire was annealed at 100°C for 1 hour, and then air-cooled for 1 hour in a standard atmosphere at a temperature of 21°C to 25°C. Note that "standard atmosphere" refers to an air atmosphere with a temperature of 21°C to 25°C, a humidity of 40% to 60%, and an atmospheric pressure of 86kPa to 106kPa. (2) Approximately 5 mg of sample was packed into an aluminum pan and kept at 40°C for 1 minute. (3) The temperature was raised to 180°C at 10°C / min and held at 180°C for 5 minutes. (4) Next, the temperature was lowered from 180°C to 4°C at a rate of 10°C / min, and after the temperature drop was completed, the sample was held at this temperature for 5 minutes. (5) Next, the temperature was increased from 40°C to 180°C at a rate of 10°C / min. In the step (3) (1st scan), differential scanning calorimetry (DSC) is performed, and the area value obtained by integrating the observed DSC curve is converted into heat quantity, which is then divided by the sample mass to obtain the heat of fusion ΔH S1 It was decided. In the step (5) (2nd scan), differential scanning calorimetry (DSC) is performed, and the area value obtained by integrating the observed DSC curve is converted into heat quantity, which is then divided by the sample mass to obtain the heat of fusion ΔH S2 It was decided.

[0094] (Physical Property 4) Heat of fusion ΔH T1 ) Each of the polyethylene compositions obtained in the examples and comparative examples was subjected to differential scanning calorimetry (DSC) using a PerkinElmer DSC-7 differential scanning calorimeter, and a DSC curve (temperature-heat flow curve) was obtained according to the following procedures and conditions. (1) As a pretreatment, the wire was processed into a strand at 190°C under a load of 2.16 kg in accordance with JIS K7210 Code D:1999, annealed at 100°C for 1 hour, and then air-cooled for 1 hour in a standard atmosphere at a temperature of 21°C to 25°C. The standard atmosphere is defined as an air atmosphere with a temperature of 21°C to 25°C, a humidity of 40% to 60%, and an atmospheric pressure of 86 kPa to 106 kPa. (2) Approximately 5 mg of sample was packed into an aluminum pan and kept at 40°C for 1 minute. (3) The temperature was raised to 180°C at 10°C / min and held at 180°C for 5 minutes. (4) Next, the temperature was lowered from 180°C to 4°C at a rate of 10°C / min, and after the temperature drop was completed, the sample was held at this temperature for 5 minutes. (5) Next, the temperature was increased from 40°C to 180°C at a rate of 10°C / min. In the step (3) (1st scan), differential scanning calorimetry (DSC) is performed, and the area value obtained by integrating the observed DSC curve is converted into heat quantity, which is then divided by the sample mass to obtain the heat of fusion ΔH T1 It was decided.

[0095] ((Property 5) Pulse NMR measurement of low-density polyethylene (B) at 120°C, proportion of highly mobile component γ Rγ, relaxation time Tγ) Pulse NMR measurements of the low-density polyethylenes (B) obtained in the examples and comparative examples were carried out as follows. First, a sample tube filled with the sample up to a height of 1 cm from the bottom was placed in a Bruker TD-NMR apparatus (model: minispec mq20) set to an internal temperature of 30°C, and the sample tube was heated according to the heating conditions shown below. The temperatures shown in the following <Heating Conditions> are values ​​obtained by measuring the internal temperature of the sample with a thermocouple. <Temperature increase conditions> (1) Set the temperature to 30°C and let it stand for 5 minutes. (2) The temperature is increased to 120°C at a rate of 5°C / min. (3) After heating to 120°C, let stand for 25 minutes. After the temperature increase was completed by the above procedure, the spin-spin relaxation time (T2, sometimes simply referred to as "relaxation time" in this specification) of the sample was measured according to the <measurement conditions> shown below. <Measurement conditions> Magnetic field strength: 0.47T Measured nuclides: 1 H(20MHz) Measurement method: Carr Purcell Meiboom Gill method Number of times accumulated: 256 Repeat time: 3 seconds The free induction decay (FID) obtained by the above measurement was subjected to curve fitting using the analysis program TD-NMR-A manufactured by Bruker. For fitting, the function shown in the following <Equation 1> was used. <Expression 1> f(t)=Rαexp(-t / Tα)+Rβexp(-t / Tβ)+Rγexp(-t / Tγ) (However, Rα+Rβ+Rγ=100) t: variable (time elapsed since pulse irradiation) Tα: Relaxation time of the low-mobility component α (ms) Rα: Presence rate of low-motile component α (%) Tβ: Relaxation time of intermediate component β (ms) Rβ: Abundance ratio of intermediate component β (%) Tγ: Relaxation time of the high-mobility component γ (ms) Rγ: The proportion of highly mobile component γ (%) The abundance ratio Rγ of the highly mobile component γ and the relaxation time Tγ of the low-density polyethylene (B) obtained in the examples and comparative examples were calculated by curve fitting of the free induction decay.

[0096] (Physical Property 6) Pulse NMR measurement of high density polyethylene (A) at 100°C, the proportion of low mobility component α (Rα), the proportion of high mobility component γ (Rγ) Pulse NMR measurement of the high-density polyethylene (A) obtained in the examples and comparative examples was carried out as follows. First, a sample tube filled with the sample up to a height of 1 cm from the bottom was placed in a Bruker TD-NMR apparatus (model: minispec mq20) set to an internal temperature of 30°C, and the sample tube was heated according to the heating conditions shown below. The temperatures shown in the following <Heating Conditions> are values ​​obtained by measuring the internal temperature of the sample with a thermocouple. <Temperature increase conditions> (1) Set the temperature to 30°C and let it stand for 5 minutes. (2) The temperature is increased to 100°C at a rate of 5°C / min. (3) After heating to 100°C, let stand for 25 minutes. After the temperature increase was completed by the above procedure, the spin-spin relaxation time (T2, sometimes simply referred to as "relaxation time" in this specification) of the sample was measured according to the <measurement conditions> shown below. <Measurement conditions> Magnetic field strength: 0.47T Measured nuclides:1 H(20MHz) Measurement method: Solid Echo method Number of times accumulated: 256 Repeat time: 3 seconds The free induction decay (FID) obtained by the above measurement was subjected to curve fitting using the analysis program TD-NMR-A manufactured by Bruker. For fitting, the function shown in the following <Equation 1> was used. <Expression 1> f(t)=Rαexp(-t / Tα)+Rβexp(-t / Tβ)+Rγexp(-t / Tγ) (However, Rα+Rβ+Rγ=100) t: variable (time elapsed since pulse irradiation) Tα: Relaxation time of the low-mobility component α (ms) Rα: Presence rate of low-motile component α (%) Tβ: Relaxation time of intermediate component β (ms) Rβ: Abundance ratio of intermediate component β (%) Tγ: Relaxation time of the high-mobility component γ (ms) Rγ: The proportion of highly mobile component γ (%) The abundance ratio Rα of the low mobility component α and the abundance ratio Rγ of the high mobility component γ in the high density polyethylene (A) obtained in the Examples and Comparative Examples were calculated by curve fitting of the free induction decay.

[0097] [Evaluation method] (Evaluation 1: High-speed thin film deposition) Each polyethylene composition obtained in the examples and comparative examples was extruded using an extruder with a screw diameter of 65 mm and L / D=30 and a die adjusted to a width of 400 mm under the conditions of a temperature of 320°C, an extrusion rate of 60 kg / hour, an air gap of 13 cm, a take-up speed of 200 m / min, and a resin film thickness of 15 μm, to produce a resin film with a basis weight of 75 g / cm. 2 The kraft paper was extrusion laminated. The laminated body was randomly cut into 20 cm squares to form samples (A). In addition, using the same extruder and die, a resin was extruded at a temperature of 320°C, an extrusion rate of 30 kg / hour, an air gap of 13 cm, a take-up speed of 120 m / min, and a resin film thickness of 10 μm, with a basis weight of 75 g / cm 2 The laminated product was randomly cut into 20 cm square pieces to be used as samples (B). Samples (A) and (B) were visually observed to confirm whether the resin layer and the kraft paper were bonded together, and this was used as an index of thin film-forming properties. Both samples were judged to have passed if the resin layer and the kraft paper were bonded together, and samples in which peeling between the resin layer and the kraft paper was observed in at least one of the samples were judged to have failed. Furthermore, using the same extruder and die, the temperature was 320°C and the extrusion rate was 60 kg / hour, and while keeping the extrusion rate constant, the take-up processing speed was gradually increased. The take-up processing speed at which the film-like resin dropping from the die broke was taken as the breaking speed, which was used as an index of high-speed processability. The above two evaluation results were combined and the high-speed thin film formation property was evaluated according to the following criteria. <Evaluation criteria> ◎: Thin film formation is acceptable and the breaking speed is over 400 m / min ○: Thin film forming property is acceptable, and breaking speed is over 350m / min to 400m / min or less △: Thin film formation is acceptable, and the breaking speed is over 300m / min to 350m / min or less ×: Thin film formation is unacceptable, or the breaking speed is 300 m / min or less

[0098] (Evaluation 2: Heat-resistant pinholes) The samples (A) and (B) obtained in the above (Evaluation 1) were placed in an oven at 130° C., left to stand for 90 seconds, and then removed. The removed samples (A) and (B) were air-cooled for 1 hour in a standard atmosphere at a temperature of 21°C to 25°C, and the number of pinholes that occurred was visually observed and used as an index of heat pinhole resistance. For pinhole observation, a toluene solution of Sudan III was used as a staining solution, and an appropriate amount was applied to the resin layer side with a brush to make pinholes easier to see. The standard atmosphere is defined as an air atmosphere with a temperature of 21°C to 25°C, a humidity of 40% to 60%, and an atmospheric pressure of 86 kPa to 106 kPa. The evaluation results of samples (A) and (B) were combined and the high-speed thin film forming properties were evaluated according to the following criteria. <Evaluation criteria> ◎: Less than 2 samples for both (A) and (B) ○: More than 2 to 5 or less in at least one of samples (A) and (B) △: More than 5 to 10 in at least one of samples (A) and (B). ×: More than 10 samples in at least one of samples (A) and (B).

[0099] (Evaluation 3: Uneven thickness) Each of the polyethylene compositions obtained in the examples and comparative examples was molded using a T-die film forming machine (HM40N manufactured by Hokushin Sangyo Co., Ltd., screw diameter 40 mm, die width 300 mm) at a cylinder temperature of 200°C, a die temperature of 210°C, an extrusion rate of 5 kg / hour, an air gap of 10 cm, and a take-up speed of 20 m / min, and both ends were trimmed by 50 mm to obtain a film made of the polyethylene composition having a thickness of 15 μm. The obtained film was cut into 1 cm squares, and the film thickness was measured using a thickness meter. A total of 20 samples were measured, and the standard deviation of the thickness was calculated and evaluated as an index of thickness unevenness according to the following criteria. <Evaluation criteria> ◎: 0.5μm or less ○: More than 0.5μm ~ 1.0μm or less △: More than 1.0μm ~ 1.5μm or less ×: More than 1.5μm

[0100] [Preparation of Components Used in Examples and Comparative Examples] (Catalyst Preparation) <Preparation of Ziegler-Natta catalyst (a-1)> An 8L stainless steel autoclave was thoroughly purged with nitrogen and charged with 1,000mL of a 2mol / L hexane solution of hydroxytrichlorosilane. 112,550 mL of a hexane solution of an organomagnesium compound represented by (OC4H9)2 (corresponding to 2.68 mol of magnesium) was added, and the reaction was carried out at 65°C for 1 hour without stirring. After the reaction was completed, the supernatant was removed and the solid was washed four times with 1,800 mL of hexane to obtain a solid support. Analysis of this solid revealed that it contained 8.31 mmol of magnesium per gram of solid. To 1,970 mL of hexane slurry containing 110 g of the carrier, 110 mL of 0.1 mol / L titanium tetrachloride hexane solution and 1 mol / L AlMg5(C4H9) were added under stirring at a temperature of 10°C. 11 110 mL of a hexane solution of an organomagnesium compound represented by (OSiH)2 was added simultaneously over 1 hour. After the addition, the reaction was continued for 1 hour at 10°C. After the reaction was completed, 1100 mL of the supernatant was removed, and the mixture was washed twice with 1100 mL of hexane to prepare Ziegler catalyst (a-1).

[0101] <Preparation of Ziegler-Natta catalyst (a-2)> An 8L stainless steel autoclave was thoroughly purged with nitrogen and charged with 1,000mL of a 2mol / L hexane solution of hydroxytrichlorosilane. 11 2,550 mL of a hexane solution of an organomagnesium compound represented by (OC4H9)2 (corresponding to 2.68 mol of magnesium) was added, and the reaction was carried out at 65°C for 1 hour without stirring. After the reaction was completed, the supernatant was removed and the solid was washed four times with 1,800 mL of hexane to obtain a solid support. Analysis of this solid revealed that it contained 8.31 mmol of magnesium per gram of solid. To 1,970 mL of hexane slurry containing 110 g of the carrier, 110 mL of 0.5 mol / L titanium tetrachloride hexane solution and 1 mol / L AlMg5(C4H9) were added under stirring at a temperature of 10°C. 11110 mL of a hexane solution of an organomagnesium compound represented by (OSiH)2 was added simultaneously over 1 hour. After the addition, the reaction was continued for 1 hour at 10°C. After the reaction was completed, 1100 mL of the supernatant was removed, and the mixture was washed twice with 1100 mL of hexane to prepare Ziegler catalyst (a-2).

[0102] <Preparation of Ziegler-Natta catalyst (a-3)> An 8L stainless steel autoclave was thoroughly purged with nitrogen and charged with 1,000mL of a 2mol / L hexane solution of hydroxytrichlorosilane. 11 2,550 mL of a hexane solution of an organomagnesium compound represented by (OC4H9)2 (corresponding to 2.68 mol of magnesium) was added, and the reaction was carried out at 65°C for 1 hour without stirring. After the reaction was completed, the supernatant was removed and the solid was washed four times with 1,800 mL of hexane to obtain a solid support. Analysis of this solid revealed that it contained 8.31 mmol of magnesium per gram of solid. To 1,970 mL of hexane slurry containing 110 g of the carrier, 110 mL of 1 mol / L titanium tetrachloride hexane solution and 1 mol / L AlMg5(C4H9) were added under stirring at a temperature of 10°C. 11 110 mL of a hexane solution of an organomagnesium compound represented by (OSiH)2 was added simultaneously over 1 hour. After the addition, the reaction was continued for 1 hour at 10°C. After the reaction was completed, 1100 mL of the supernatant was removed, and the mixture was washed twice with 1100 mL of hexane to prepare Ziegler catalyst (a-3).

[0103] <Preparation of Ziegler-Natta catalyst (a-4)> An 8L stainless steel autoclave was thoroughly purged with nitrogen and charged with 1,000mL of a 2mol / L hexane solution of hydroxytrichlorosilane. 11 2,550 mL of a hexane solution of an organomagnesium compound represented by (OC4H9)2 (corresponding to 2.68 mol of magnesium) was added, and the reaction was carried out at 65°C for 1 hour without stirring. After the reaction was completed, the supernatant was removed and the solid was washed four times with 1,800 mL of hexane to obtain a solid support. Analysis of this solid revealed that it contained 8.31 mmol of magnesium per gram of solid. To 1,970 mL of hexane slurry containing 110 g of the carrier, 110 mL of hexane solution of 0.25 mol / L titanium tetrachloride and 1 mol / L AlMg5(C4H9) were added under stirring at a temperature of 10°C. 11 110 mL of a hexane solution of an organomagnesium compound represented by (OSiH)2 was added simultaneously over 1 hour. After the addition, the reaction was continued for 1 hour at 10°C. After the reaction was completed, 1100 mL of the supernatant was removed, and the mixture was washed twice with 1100 mL of hexane to prepare Ziegler catalyst (a-4).

[0104] <Preparation of Ziegler-Natta catalyst (a-5)> In the same manner as in Patent No. 6792957, a 200 mL stainless steel autoclave was filled with nitrogen and charged with AlMg6(C4H9) 12 40 mL of a hexane solution of an organomagnesium compound represented by the formula (OC3H7)3 (corresponding to a total of 37.8 mmol of aluminum and magnesium) was charged, and 40 mL of hexane containing 2.27 g (37.8 mmol) of methylhydrogenpolysiloxane was added dropwise over 30 minutes while stirring at 25°C. After the dropwise addition, the temperature was raised to 80°C, and the reaction was carried out with stirring for 3 hours to obtain an organomagnesium compound to be contacted with a titanium compound. 2400 mL of hexane was charged into an 8 L stainless steel autoclave that had been thoroughly purged with nitrogen, and the solution was stirred at -5°C while the organomagnesium compound of the formula AlMg6(C4H9) 12 1300 mL of a hexane solution of an organomagnesium compound represented by (OC3H7)3 (equivalent to 521 mmol of magnesium) and 1300 mL of a hexane solution of 0.5 mol / L titanium tetrachloride were added dropwise simultaneously over a period of 2 hours. After the addition, the mixture was further stirred and aged at 10°C for 1 hour, after which the supernatant was removed and the mixture was washed four times with 3000 mL of hexane to prepare Ziegler-Natta catalyst (a-5).

[0105] <Preparation of Ziegler-Natta catalyst (a-6)> An 8L stainless steel autoclave was thoroughly purged with nitrogen and charged with 1,000mL of a 2mol / L hexane solution of hydroxytrichlorosilane. The contents were stirred at 65°C and heated to 65°C. 11 2,550 mL of a hexane solution of an organomagnesium compound represented by (OC4H9)2 (corresponding to 2.68 mol of magnesium) was added dropwise over 4 hours, and the reaction was continued for another 1 hour at 65°C with stirring. After the reaction was completed, the supernatant was removed and the solid was washed four times with 1,800 mL of hexane to obtain a solid support. Analysis of this solid revealed that it contained 8.31 mmol of magnesium per gram of solid. To 1,970 mL of hexane slurry containing 110 g of the carrier, 110 mL of 1 mol / L titanium tetrachloride hexane solution and 1 mol / L AlMg5(C4H9) were added under stirring at a temperature of 10°C. 11 110 mL of a hexane solution of an organomagnesium compound represented by (OSiH)2 was added simultaneously over 1 hour. After the addition, the reaction was continued for 1 hour at 10°C. After the reaction was completed, 1100 mL of the supernatant was removed, and the mixture was washed twice with 1100 mL of hexane to prepare Ziegler catalyst (a-6).

[0106] <Preparation of Ziegler-Natta catalyst (a-7)> An 8L stainless steel autoclave was thoroughly purged with nitrogen and charged with 1,000mL of a 2mol / L hexane solution of hydroxytrichlorosilane. The contents were stirred at 65°C and heated to 65°C. 11 2,550 mL of a hexane solution of an organomagnesium compound represented by (OC4H9)2 (corresponding to 2.68 mol of magnesium) was added dropwise over 4 hours, and the reaction was continued for another 1 hour at 65°C with stirring. After the reaction was completed, the supernatant was removed and the solid was washed four times with 1,800 mL of hexane to obtain a solid support. Analysis of this solid revealed that it contained 8.31 mmol of magnesium per gram of solid. To 1,970 mL of hexane slurry containing 110 g of the carrier, 110 mL of 0.1 mol / L titanium tetrachloride hexane solution and 1 mol / L AlMg5(C4H9) were added under stirring at a temperature of 10°C. 11 110 mL of a hexane solution of an organomagnesium compound represented by (OSiH)2 was added simultaneously over 1 hour. After the addition, the reaction was continued for 1 hour at 10°C. After the reaction was completed, 1100 mL of the supernatant was removed, and the mixture was washed twice with 1100 mL of hexane to prepare Ziegler catalyst (a-7).

[0107] <Preparation of Metallocene Catalyst (b-1)> Similar to the method described in Japanese Patent No. 6912290, 40 g of catalyst carrier silica (average particle size 15 μm, compressive strength 3 MPa) dehydrated at 600°C was dispersed in 800 mL of hexane in a 1.8 L autoclave under a nitrogen atmosphere to obtain a slurry. The resulting slurry was maintained at 25°C, and 84 mL of a hexane solution of triethylaluminum (concentration 1 mol / L) was added while stirring. The mixture was then stirred for 2 hours to react the triethylaluminum with the surface hydroxyl groups of the silica, yielding a hexane slurry of component [a] in which the surface hydroxyl groups of the silica were capped with triethylaluminum. On the other hand, 200 mmol of [(Nt-butylamido)(tetramethyl-η5-cyclopentadienyl)dimethylsilane]titanium dimethyl (hereinafter referred to as "titanium complex") was dissolved in 1000 mL of Isopar E (registered trademark) (the trade name of a hydrocarbon mixture manufactured by Exxon Chemical Company (USA)), 20 mL of a 1 mol / L hexane solution of n-butylethylmagnesium was added, and further hexane was added to adjust the titanium complex concentration to 0.1 mol / L, thereby obtaining component [b]. Furthermore, 5.7 g of bis(hydrogenated tallow alkyl)methylammonium-tris(pentafluorophenyl)(4-hydroxyphenyl)borate (hereinafter referred to as "borate compound") was added and dissolved in 50 mL of toluene to obtain a 100 mmol / L toluene solution of the borate compound. 5 mL of a 1 mol / L hexane solution of diethylaluminum ethoxide was added to this toluene solution at room temperature, and further hexane was added to adjust the borate compound concentration in the solution to 70 mmol / L. The mixture was then stirred at room temperature for 1 hour to obtain a reaction mixture [c] containing the borate compound. The hexane slurry of the component [a] was heated to 45 to 50°C, and then the stirring speed was set to 600 rpm. 9.2 mL of the reaction mixture [c] and 6.4 mL of the component [b] were simultaneously added dropwise to the hexane slurry of the component [a] over 20 minutes, followed by stirring at 50°C for 1 hour, thereby allowing the catalytically active species to penetrate into the silica. The supernatant containing the unreacted borate compound and titanium complex from the resulting reaction mixture was then removed by decantation, thereby supporting the catalytically active species within the silica. After cooling to 10-15°C, 36.8 mL of the reaction mixture [c] and 25.6 mL of the component [b] were simultaneously added dropwise over 80 minutes, followed by stirring at 15-20°C for 3 hours, resulting in the reaction and precipitation of the titanium complex and borate, and the physical adsorption of the catalytically active species onto the silica surface. The supernatant containing the unreacted borate compound and titanium complex from the resulting reaction mixture was then removed by decantation, yielding a supported, constrained geometry metallocene catalyst (b-1) in which the catalytically active species was formed on and within the silica surface.

[0108] (High density polyethylene (A)) <Production of high density polyethylene (A-1)> Continuous polymerization was carried out in a 280L vessel-type polymerization reactor equipped with a stirrer under conditions of a polymerization temperature of 70°C, a polymerization pressure of 1 MPa, and an average residence time of 1.6 hours. Dehydrated n-hexane was used as the solvent at 40 L / h, and the Ziegler-Natta catalyst (a-1) was used at 4.0 g / h. Triisobutylaluminum was used as the liquid cocatalyst component at 24 mmol / h (calculated as Al atoms). Hydrogen was added to control molecular weight at a concentration of 40.2 mol% of the ethylene gas phase. Dehydrated n-hexane was introduced from the bottom of the polymerization reactor. Hydrogen was introduced from the catalyst introduction line, along with the catalyst, midway between the liquid surface and the bottom of the polymerization reactor to allow pre-exposure to the catalyst. Ethylene was introduced from the bottom of the polymerization reactor. The polymerization slurry in the polymerization reactor was introduced into a flash tank at a pressure of 0.08 MPa and a temperature of 75°C so that the level of the polymerization reactor was kept constant, and unreacted ethylene and hydrogen were separated. Next, the polymerization slurry was continuously sent to a centrifuge so as to keep the level of the polymerization reactor constant, and the polymer was separated from the other components such as the solvent, etc. At this time, the content of the solvent, etc. relative to the polymer was 45% by mass. The separated high density polyethylene powder was dried at 85°C with nitrogen blowing. Next, 300 ppm by mass of pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate] was added as an antioxidant to the obtained polyethylene powder, and the mixture was melt-kneaded at a set temperature of 200°C in a twin-screw extruder manufactured by The Japan Steel Works, Ltd. (screw diameter 44 mm, L / D=35, L: distance (m) from raw material inlet to discharge outlet, D: inner diameter (m) of extruder; the same applies hereinafter) to obtain pelletized high-density polyethylene (A-1).

[0109] <Production of High-Density Polyethylene (A-2)> High-density polyethylene (A-2) was obtained by the same procedure as in the production of high-density polyethylene (A-1), except that the Ziegler-Natta catalyst (a-2) was fed as the catalyst at a rate of 0.8 g / hour and 1-butene was fed so as to have a concentration of 0.29 mol % relative to the gas phase ethylene concentration.

[0110] <Production of High-Density Polyethylene (A-3)> High density polyethylene (A-3) was obtained by the same procedure as in the production of high density polyethylene (A-1), except that the Ziegler-Natta catalyst (a-3) was fed as the catalyst at a rate of 0.4 g / hour.

[0111] <Production of High-Density Polyethylene (A-4)> High-density polyethylene (A-4) was obtained by the same procedure as in the production of high-density polyethylene (A-1), except that the Ziegler-Natta catalyst (a-4) was supplied as a catalyst at a rate of 1.6 g / hour, hydrogen for molecular weight adjustment was supplied at 28.6 mol % based on the gas phase ethylene concentration, and 1-butene was supplied at 0.29 mol % based on the gas phase ethylene concentration.

[0112] <Production of High-Density Polyethylene (A-5)> With reference to the method of Example (A-2) of Japanese Patent No. 6792957, polymerization was carried out in the same manner as for the high-density polyethylene (A-1), except that Ziegler-Natta catalyst (a-5) was supplied at a rate of 0.3 g / hour, the polymerization temperature was 86°C, and the amount of hydrogen used to adjust the molecular weight was 28.6 mol% relative to the gas-phase ethylene concentration, to obtain high-density polyethylene resin (A-5).

[0113] <Production of High-Density Polyethylene (A-6)> High-density polyethylene (A-6) was obtained by the same procedure as in the production of high-density polyethylene (A-1), except that the Ziegler-Natta catalyst (a-6) was fed as the catalyst at a rate of 0.4 g / hour and hydrogen for molecular weight adjustment was fed so as to give a concentration of 54.3 mol % based on the gas phase ethylene concentration.

[0114] <Production of High-Density Polyethylene (A-7)> Using the method described in Example (A-4) of Japanese Patent No. 6912290 as a reference, continuous polymerization was carried out using a 340 L vessel-type polymerization reactor equipped with a stirrer under conditions of a polymerization temperature of 80°C, a polymerization pressure of 0.98 MPa, and an average residence time of 3.2 hours. Dehydrated normal hexane was fed as the solvent at 40 L / h, the above-mentioned metallocene catalyst (b-1) was fed as the catalyst at 1.4 mmol / h (Ti atom equivalent), and triisobutylaluminum was fed as the liquid cocatalyst component at 20 mol / h (Al atom equivalent). Ethylene was polymerized by feeding hydrogen for molecular weight control at a concentration of 0.47 mol% relative to the gas-phase ethylene concentration. Dehydrated normal hexane was fed from the bottom of the polymerization reactor, and hydrogen was fed from the catalyst introduction line midway between the liquid surface and the bottom of the polymerization reactor to allow pre-contact with the catalyst. Ethylene was fed from the bottom of the polymerization reactor. The polymerization slurry in the polymerization reactor was introduced into a flash tank at a pressure of 0.08 MPa and a temperature of 75°C so that the level of the polymerization reactor was kept constant, and unreacted ethylene and hydrogen were separated. Next, the polymerization slurry was continuously sent to a centrifuge so as to keep the level of the polymerization reactor constant, and the polymer was separated from the other components such as the solvent, etc. At this time, the content of the solvent relative to the polymer was 45%. The separated high-density polyethylene powder was dried at 85°C while blowing nitrogen, and then melt-kneaded at a set temperature of 200°C in a twin-screw extruder (screw diameter 44 mm, L / D = 35) manufactured by Nippon Steel Corporation, to obtain pelletized high-density polyethylene (A-7).

[0115] <Production of high density polyethylene (A-8)> High-density polyethylene (A-8) was obtained by the same procedure as in the production of high-density polyethylene (A-1), except that the Ziegler-Natta catalyst (a-7) was fed as the catalyst at a rate of 4.0 g / hour, hydrogen for molecular weight adjustment was fed at 28.6 mol % based on the gas phase ethylene concentration, and 1-butene was fed at 1.32 mol % based on the gas phase ethylene concentration.

[0116] Table 1 below shows the physical properties of the resulting high-density polyethylenes (A-1) to (A-8).

[0117] [Table 1]

[0118] (Low-density polyethylene (B)) <Production of low-density polyethylene (B-1)> Using ethylene gas as the raw material, a polymer was polymerized in an autoclave reactor equipped with a stirrer at an average polymerization temperature of 260°C, with the temperature of the most upstream initiator addition point set at 250°C and the temperature of the most downstream initiator addition point set at 270°C, under a polymerization pressure of 140 MPa and using t-butyl peroxyacetate as the initiator. The conversion at the most upstream reaction initiation point was 11%. Subsequently, the molten polymer was granulated using a single-screw extruder manufactured by Nippon Steel Corporation (screw diameter 100 mm, L / D = 24, L: distance from raw material inlet to outlet (m), D: inner diameter of polymerization reactor (m); the same applies hereinafter), to obtain pelletized low-density polyethylene (B-1).

[0119] <Production of low-density polyethylene (B-2)> Using ethylene gas as the raw material, a polymer was polymerized in an autoclave reactor equipped with a stirrer at an average polymerization temperature of 235°C, with the temperature of the most upstream initiator addition point set at 220°C and the temperature of the most downstream initiator addition point set at 250°C, a polymerization pressure of 150MPa, 1.0 mol% of the ethylene raw material changed to isobutane, and t-butyl peroxyacetate was used as the reaction initiator. The conversion at the most upstream reaction initiation point was 12%. Subsequently, the mixture was granulated in the same manner as in the production method for the low-density polyethylene (B-1) to obtain pelletized low-density polyethylene (B-2).

[0120] <Production of low-density polyethylene (B-3)> Using ethylene gas as the raw material, a polymer was polymerized in a tubular reactor at an average polymerization temperature of 295°C, with the temperature of the most upstream initiator addition point set at 280°C and the temperature of the most downstream initiator addition point set at 310°C, under a polymerization pressure of 190 MPa. 0.3 mol% of the ethylene raw material was replaced with propylene, and t-butylperoxy-2-ethylhexanoate was used as the reaction initiator. The conversion at the most upstream reaction initiation point was 5%. Subsequently, the mixture was granulated in the same manner as in the production method for the low-density polyethylene (B-1) to obtain a pellet-shaped low-density polyethylene (B-3).

[0121] <Production of low-density polyethylene (B-4)> Using ethylene gas as the raw material, a polymer was polymerized in an autoclave reactor equipped with a stirrer at an average polymerization temperature of 250°C, with the temperature at the most upstream initiator addition point set at 250°C and the temperature at the most downstream initiator addition point set at 250°C, a polymerization pressure of 160MPa, 1.5mol% of the ethylene raw material changed to isobutane, and t-butyl peroxyacetate was used as the reaction initiator. The conversion at the most upstream reaction initiation point was 15%. Subsequently, the mixture was granulated in the same manner as in the production method for the low-density polyethylene (B-1) to obtain pelletized low-density polyethylene (B-4).

[0122] <Production of low-density polyethylene (B-5)> Using ethylene gas as the raw material, a polymer was polymerized in an autoclave reactor equipped with a stirrer at an average polymerization temperature of 260°C, with the temperature of the most upstream initiator addition point set at 250°C and the temperature of the most downstream initiator addition point set at 270°C, at a polymerization pressure of 160MPa, with 1.5mol% of the ethylene raw material replaced with isobutane, and using t-butylperoxy-2-ethylhexanoate as the initiator. The conversion at the most upstream reaction initiation point was 9%. Subsequently, the mixture was granulated in the same manner as in the production method for the low-density polyethylene (B-1) to obtain a pellet-shaped low-density polyethylene (B-5).

[0123] <Production of low-density polyethylene (B-6)> Using ethylene gas as the raw material, a polymer was polymerized in an autoclave reactor equipped with a stirrer at an average polymerization temperature of 220°C, with the temperature at the most upstream initiator addition point set at 220°C and the temperature at the most downstream initiator addition point set at 220°C, a polymerization pressure of 130MPa, 1.5mol% of the ethylene raw material changed to isobutane, and t-butyl peroxyacetate was used as the reaction initiator. The conversion at the most upstream reaction initiation point was 15%. Subsequently, the mixture was granulated in the same manner as in the production method for the low-density polyethylene (B-1) to obtain pelletized low-density polyethylene (B-6).

[0124] <Production of low-density polyethylene (B-7)> Using ethylene gas as the raw material, a polymer was polymerized in an autoclave reactor equipped with a stirrer at an average polymerization temperature of 215°C, with the temperature of the most upstream initiator addition point set at 210°C and the temperature of the most downstream initiator addition point set at 220°C, under a polymerization pressure of 120 MPa and using t-butyl peroxyacetate as the initiator. The conversion at the most upstream reaction initiation point was 8%. Subsequently, the mixture was granulated in the same manner as in the production method for the low-density polyethylene (B-1) to obtain pelletized low-density polyethylene (B-7).

[0125] <Production of low-density polyethylene (B-8)> Using ethylene gas as the raw material, a polymer was polymerized in a tubular reactor at an average polymerization temperature of 225°C, with the temperature of the most upstream initiator addition point set at 210°C and the temperature of the most downstream initiator addition point set at 240°C, under a polymerization pressure of 210 MPa. 1.5 mol% of the ethylene raw material was replaced with propylene, and t-butylperoxy-2-ethylhexanoate was used as the reaction initiator. The conversion at the most upstream reaction initiation point was 5%. Subsequently, the mixture was granulated in the same manner as in the production method for the low-density polyethylene (B-1) to obtain a pellet-shaped low-density polyethylene (B-8).

[0126] <Production of low-density polyethylene (B-9)> Using ethylene gas as the raw material, a polymer was polymerized in an autoclave reactor equipped with a stirrer at an average polymerization temperature of 260°C, with the temperature of the most upstream initiator addition point set at 259°C and the temperature of the most downstream initiator addition point set at 260°C, under a polymerization pressure of 128 MPa and using t-butyl peroxyacetate as the initiator. The conversion rate at the most upstream reaction initiation point was 8%. Subsequently, the mixture was granulated in the same manner as in the production method for the low-density polyethylene (B-1) to obtain a pellet-shaped low-density polyethylene (B-9).

[0127] <Production of low-density polyethylene (B-10)> Using the method of Example (B-2) of Japanese Patent No. 6792957 as reference, ethylene gas was used as the raw material, and a polymer was polymerized in a tubular reactor at an average polymerization temperature of 300°C, with the temperature of the most upstream initiator addition point set at 300°C and the temperature of the most downstream initiator addition point set at 300°C, a polymerization pressure of 240 MPa, 0.3 mol% of the ethylene raw material replaced with propylene, and t-butyl peroxyacetate was used as the reaction initiator. The conversion at the most upstream reaction initiation point was 9%. Subsequently, the mixture was granulated in the same manner as in the production method for the low-density polyethylene (B-1) to obtain a pellet-shaped low-density polyethylene (B-10).

[0128] <Production of low-density polyethylene (B-11)> Using the method of Example (B-1) of Japanese Patent No. 6912290 as a reference, ethylene gas was used as the raw material in an autoclave reactor equipped with a stirrer. The average polymerization temperature was set to 258°C, the temperature at the most upstream initiator addition point was 256°C, and the temperature at the most downstream initiator addition point was 260°C. The polymerization pressure was 168 MPa, and 1.85 mol% of the ethylene raw material was changed to isobutane. As the reaction initiator, t-butyl peracetate and t-butyl peroctate were mixed in a 2:8 ratio and diluted with isododecane to make a mixture of 11% by mass. The conversion at the most upstream reaction initiation point was 9%. Subsequently, the mixture was granulated in the same manner as in the production method for the low-density polyethylene (B-1) to obtain a pellet-shaped low-density polyethylene (B-11).

[0129] Table 2 below shows the physical properties of the obtained low-density polyethylenes (B-1) to (B-11).

[0130] [Table 2]

[0131] (Polyethylene composition) Example 1: Preparation of Polyethylene Composition C-1 High-density polyethylene (A-1) and low-density polyethylene (B-1) were mixed at 50% by mass and 50% by mass, respectively, and mixed for 2 hours in a tumbler blender. The blended mixture was melt-kneaded and pelletized using a single-screw extruder (manufactured by Nippon Steel Corporation) (screw diameter 90 mm, cylinder diameter 100 mm, equipped with a screen mesh with a porosity of 28%, L / D = 24) at an extrusion rate of 160 kg / h and a set temperature of 200°C. The resin pressure at this time was 7.8 MPa.

[0132] Example 2: Preparation of Polyethylene Composition C-2 High-density polyethylene (A-1) and low-density polyethylene (B-1) were mixed at 25% by mass and 75% by mass, respectively, and mixed for 2 hours in a tumbler blender. The blended mixture was melt-kneaded and pelletized using a single-screw extruder (manufactured by Nippon Steel Corporation) (screw diameter 90 mm, cylinder diameter 100 mm, equipped with a screen mesh with a porosity of 28%, L / D = 24) at an extrusion rate of 160 kg / h and a set temperature of 200°C. The resin pressure at this time was 9.3 MPa.

[0133] Example 3: Production of Polyethylene Composition C-3 High-density polyethylene (A-1) and low-density polyethylene (B-1) were mixed at 70% by mass and 30% by mass, respectively, and mixed in a tumbler blender for 2 hours. The blended mixture was melt-kneaded and pelletized using a single-screw extruder (manufactured by Nippon Steel Corporation) (screw diameter 90 mm, cylinder diameter 100 mm, equipped with a screen mesh with a porosity of 28%, L / D = 24) at an extrusion rate of 40 kg / h and a set temperature of 200°C. The resin pressure at this time was 2.4 MPa.

[0134] Example 4: Production of Polyethylene Composition C-4 High-density polyethylene (A-2) and low-density polyethylene (B-2) were mixed at 30% by mass and 70% by mass, respectively, and mixed in a tumbler blender for 2 hours. The blended mixture was melt-kneaded and pelletized using a single-screw extruder (manufactured by Nippon Steel Corporation) (screw diameter 90 mm, cylinder diameter 100 mm, equipped with a screen mesh with a porosity of 28%, L / D = 24) at an extrusion rate of 160 kg / h and a set temperature of 200°C. The resin pressure at this time was 7.1 MPa.

[0135] Example 5: Production of Polyethylene Composition C-5 High-density polyethylene (A-3) and low-density polyethylene (B-3) were mixed at 50% by mass and 50% by mass, respectively, and mixed for 2 hours in a tumbler blender. The blended mixture was melt-kneaded and pelletized using a single-screw extruder (manufactured by Nippon Steel Corporation) (screw diameter 90 mm, cylinder diameter 100 mm, equipped with a screen mesh with a porosity of 28%, L / D = 24) at an extrusion rate of 160 kg / h and a set temperature of 200°C. The resin pressure at this time was 6.4 MPa.

[0136] Example 6: Production of Polyethylene Composition C-6 High-density polyethylene (A-4) and low-density polyethylene (B-4) were mixed at 60% by mass and 40% by mass, respectively, and mixed for 2 hours in a tumbler blender. The blended mixture was melt-kneaded and pelletized using a single-screw extruder (manufactured by Nippon Steel Corporation) (screw diameter 90 mm, cylinder diameter 100 mm, equipped with a screen mesh with a porosity of 28%, L / D = 24) at an extrusion rate of 160 kg / h and a set temperature of 200°C. The resin pressure at this time was 5.9 MPa.

[0137] Example 7: Production of Polyethylene Composition C-7 High-density polyethylene (A-2) and low-density polyethylene (B-5) were mixed at 45% by mass and 55% by mass, respectively, and mixed for 2 hours in a tumbler blender. The blended mixture was melt-kneaded and pelletized using a single-screw extruder (manufactured by Nippon Steel Corporation) (screw diameter 90 mm, cylinder diameter 100 mm, equipped with a screen mesh with a porosity of 28%, L / D = 24) at an extrusion rate of 160 kg / h and a set temperature of 200°C. The resin pressure at this time was 5.8 MPa.

[0138] Example 8: Production of Polyethylene Composition C-8 High-density polyethylene (A-3) and low-density polyethylene (B-5) were mixed at 40% by mass and 60% by mass, respectively, and mixed in a tumbler blender for 2 hours. The blended mixture was melt-kneaded and pelletized using a single-screw extruder (manufactured by Nippon Steel Corporation) (screw diameter 90 mm, cylinder diameter 100 mm, equipped with a screen mesh with a porosity of 28%, L / D = 24) at an extrusion rate of 160 kg / h and a set temperature of 200°C. The resin pressure at this time was 5.5 MPa.

[0139] Example 9: Production of Polyethylene Composition C-9 High-density polyethylene (A-3) and low-density polyethylene (B-2) were mixed at 65% by mass and 35% by mass, respectively, and mixed for 2 hours in a tumbler blender. The blended mixture was melt-kneaded and pelletized using a single-screw extruder (manufactured by Nippon Steel Corporation) (screw diameter 90 mm, cylinder diameter 100 mm, equipped with a screen mesh with a porosity of 55%, L / D = 24) at an extrusion rate of 80 kg / h and a set temperature of 200°C. The resin pressure at this time was 5.9 MPa.

[0140] Example 10: Production of Polyethylene Composition C-10 High-density polyethylene (A-4) and low-density polyethylene (B-6) were mixed at 70% by mass and 30% by mass, respectively, and mixed in a tumbler blender for 2 hours. The blended mixture was melt-kneaded and pelletized using a single-screw extruder (manufactured by Nippon Steel Corporation) (screw diameter 90 mm, cylinder diameter 100 mm, equipped with a screen mesh with a porosity of 28%, L / D = 24) at an extrusion rate of 160 kg / h and a set temperature of 200°C. The resin pressure at this time was 7.0 MPa.

[0141] Comparative Example 1: Production of Polyethylene Composition C-11 High-density polyethylene (A-1) and low-density polyethylene (B-1) were mixed at 10% by mass and 90% by mass, respectively, and mixed for 2 hours in a tumbler blender. The blended mixture was melt-kneaded and pelletized using a single-screw extruder (manufactured by Nippon Steel Corporation) (screw diameter 90 mm, cylinder diameter 100 mm, equipped with a screen mesh with a porosity of 28%, L / D = 24) at an extrusion rate of 160 kg / h and a set temperature of 200°C. The resin pressure at this time was 9.0 MPa.

[0142] Comparative Example 2: Production of Polyethylene Composition C-12 High-density polyethylene (A-1) and low-density polyethylene (B-1) were mixed at 90% by mass and 10% by mass, respectively, and mixed for 2 hours in a tumbler blender. The blended mixture was melt-kneaded and pelletized using a single-screw extruder (manufactured by Nippon Steel Corporation) (screw diameter 90 mm, cylinder diameter 100 mm, equipped with a screen mesh with a porosity of 28%, L / D = 24) at an extrusion rate of 160 kg / h and a set temperature of 200°C. The resin pressure at this time was 8.1 MPa.

[0143] Comparative Example 3: Production of Polyethylene Composition C-13 High-density polyethylene (A-3) and low-density polyethylene (B-4) were mixed at 40% by mass and 60% by mass, respectively, and mixed in a tumbler blender for 2 hours. The blended mixture was melt-kneaded and pelletized using a single-screw extruder (manufactured by Nippon Steel Corporation) (screw diameter 90 mm, cylinder diameter 100 mm, equipped with a screen mesh with a porosity of 28%, L / D = 24) at an extrusion rate of 160 kg / h and a set temperature of 200°C. The resin pressure at this time was 5.8 MPa.

[0144] Comparative Example 4: Production of Polyethylene Composition C-14 High-density polyethylene (A-2) and low-density polyethylene (B-7) were mixed at 60% by mass and 40% by mass, respectively, and mixed for 2 hours in a tumbler blender. The blended mixture was melt-kneaded and pelletized using a single-screw extruder (manufactured by Nippon Steel Corporation) (screw diameter 90 mm, cylinder diameter 100 mm, equipped with a screen mesh with a porosity of 28%, L / D = 24) at an extrusion rate of 160 kg / h and a set temperature of 200°C. The resin pressure at this time was 7.1 MPa.

[0145] Comparative Example 5: Production of Polyethylene Composition C-15 High-density polyethylene (A-3) and low-density polyethylene (B-6) were mixed at 50% by mass and 50% by mass, respectively, and mixed for 2 hours in a tumbler blender. The blended mixture was melt-kneaded and pelletized using a single-screw extruder (manufactured by Nippon Steel Corporation) (screw diameter 90 mm, cylinder diameter 100 mm, equipped with a screen mesh with a porosity of 28%, L / D = 24) at an extrusion rate of 160 kg / h and a set temperature of 200°C. The resin pressure at this time was 6.2 MPa.

[0146] Comparative Example 6: Production of Polyethylene Composition C-16 High-density polyethylene (A-6) and low-density polyethylene (B-5) were mixed at 50% by mass and 50% by mass, respectively, and mixed for 2 hours in a tumbler blender. The blended mixture was melt-kneaded and pelletized using a single-screw extruder (manufactured by Nippon Steel Corporation) (screw diameter 90 mm, cylinder diameter 100 mm, equipped with a screen mesh with a porosity of 28%, L / D = 24) at an extrusion rate of 40 kg / h and a set temperature of 200°C. The resin pressure at this time was 2.4 MPa.

[0147] Comparative Example 7: Production of Polyethylene Composition C-17 High-density polyethylene (A-4) and low-density polyethylene (B-8) were mixed at 60% by mass and 40% by mass, respectively, and mixed for 2 hours in a tumbler blender. The blended mixture was melt-kneaded and pelletized using a single-screw extruder (manufactured by Nippon Steel Corporation) (screw diameter 90 mm, cylinder diameter 100 mm, equipped with a screen mesh with a porosity of 55%, L / D = 24) at an extrusion rate of 80 kg / h and a set temperature of 200°C. The resin pressure at this time was 2.9 MPa.

[0148] Comparative Example 8: Production of Polyethylene Composition C-18 High-density polyethylene (A-7) and low-density polyethylene (B-11) were mixed at 50% by mass and 50% by mass, respectively, and mixed for 2 hours in a tumbler blender. The blended mixture was melt-kneaded and pelletized using a single-screw extruder (manufactured by Nippon Steel Corporation) (screw diameter 90 mm, cylinder diameter 100 mm, equipped with a screen mesh with a porosity of 55%, L / D = 24) at an extrusion rate of 80 kg / h and a set temperature of 200°C. The resin pressure at this time was 2.4 MPa.

[0149] Comparative Example 9: Production of Polyethylene Composition C-19 High-density polyethylene (A-6) and low-density polyethylene (B-9) were mixed at 50% by mass and 50% by mass, respectively, and mixed for 2 hours in a tumbler blender. The blended mixture was melt-kneaded and pelletized using a single-screw extruder (manufactured by Nippon Steel Corporation) (screw diameter 90 mm, cylinder diameter 100 mm, equipped with a screen mesh with a porosity of 55%, L / D = 24) at an extrusion rate of 80 kg / h and a set temperature of 200°C. The resin pressure at this time was 2.7 MPa.

[0150] Comparative Example 10: Production of Polyethylene Composition C-20 High-density polyethylene (A-5) and low-density polyethylene (B-10) were mixed at 50% by mass and 50% by mass, respectively, and mixed for 2 hours in a tumbler blender. The blended mixture was melt-kneaded and pelletized using a single-screw extruder (manufactured by Nippon Steel Corporation) (screw diameter 90 mm, cylinder diameter 100 mm, equipped with a screen mesh with a porosity of 55%, L / D = 24) at an extrusion rate of 80 kg / h and a set temperature of 200°C. The resin pressure at this time was 3.9 MPa.

[0151] Comparative Example 11: Production of Polyethylene Composition C-21 High-density polyethylene (A-8) and low-density polyethylene (B-11) were mixed at 20% by mass and 80% by mass, respectively, and mixed for 2 hours in a tumbler blender. The blended mixture was melt-kneaded and pelletized using a Nippon Steel Corporation single-screw extruder (screw diameter 90 mm, cylinder diameter 100 mm, equipped with a 55% porosity screen mesh, L / D = 24) at an extrusion rate of 80 kg / h and a set temperature of 200°C. The resin pressure at this time was 3.6 MPa.

[0152] Tables 3 and 4 show the physical properties and evaluation results of the obtained polyethylene compositions (C-1) to (C-21).

[0153] [Table 3]

[0154] [Table 4] [Industrial Applicability]

[0155] The polyethylene composition of the present invention has industrial applicability as a raw material for multilayer films and heat-resistant laminates, in which heat resistance is particularly important, such as protective films.

Claims

1. Density is 942 kg / m 3 and a high-density polyethylene (A) having a density of 930 kg / m 3 A mixture of the following high-pressure low-density polyethylenes (B): In pulse NMR measurement of the high-pressure low-density polyethylene (B) at 120°C, when a free induction decay curve obtained by the Carr Purcell Meiboom Gill (CPMG) method is approximated with three components, the relaxation time Tγ of the high-mobility component γ is 100 ms or more and 200 ms or less; A polyethylene composition satisfying the following <Condition (A)> to <Condition (D)>: <Condition (A)> Melt flow rate at 190°C and a load of 2.16 kg is 1.0 g / 10 min or more. 0 g / 10 min or less. <Condition (B)> Density is 925 kg / m 3 More than 970kg / m 3 The following is the result. <Condition (C)> After carrying out the pretreatment under the following [pretreatment conditions (S)], the heat of fusion calculated from the temperature-heat flow curve obtained by the first scan of differential scanning calorimetry (DSC) measured within 24 hours is expressed as ΔH S1 The heat of fusion calculated from the temperature-heat flow curve obtained by the second scan is ΔH S2 When The ΔH S1 and the ΔH S2 The value is 110 J / g or more and 240 J / g or less, ΔH S1 / ΔH S2 The value of is 1.000 or more and 1.100 or less. [Pretreatment conditions (S)] According to JIS K7210 Code D:1999, the wire is processed into a strand at 190°C under a load of 2.16 kg, annealed at 120°C for 1 hour, and then air-cooled for 1 hour in a standard atmosphere at a temperature of 21°C to 25°C. It is then annealed at 100°C for 1 hour, and then air-cooled for 1 hour in a standard atmosphere at a temperature of 21°C to 25°C. <Condition (D)> After carrying out the pretreatment under the following [pretreatment conditions (T)], the heat of fusion calculated from the temperature-heat flow curve obtained by the first scan of differential scanning calorimetry (DSC) measured within 24 hours is expressed as ΔH T1 When The ΔH T1 The value is 110 J / g or more and 240 J / g or less, The ΔH S1 ΔH is the ratio of S1 / ΔH T1 The value of is 1.000 or more and 1.100 or less. [Pretreatment conditions (T)] According to JIS K7210 Code D:1999, the wire is processed into a strand at 190°C under a load of 2.16 kg, annealed at 100°C for 1 hour, and then air-cooled in a standard atmosphere at a temperature of 21°C to 25°C for 1 hour.

2. Density is 942 kg / m 3 The above high-density polyethylene (A), Density is 930 kg / m 3 A mixture of the following high-pressure low-density polyethylenes (B): When the high-pressure low-density polyethylene (B) is subjected to pulse NMR measurement at 120°C using the Carr Purcell Meiboom Gill (CPMG) method, a three-component approximation of the free induction decay curve shows: The abundance ratio Rγ of the high mobility component γ is 9% or more and 24% or less, and the relaxation time Tγ of the high mobility component γ is 100 ms or more and 200 ms or less. The polyethylene composition of claim 1.

3. Density is 942 kg / m 3 The above high-density polyethylene (A), Density is 930 kg / m 3 A mixture of the following high-pressure low-density polyethylenes (B): When the high-density polyethylene (A) is subjected to pulse NMR measurement at 100°C using a solid echo (SE) method, a free induction decay curve thereof is approximated by three components, The abundance ratio Rα of the low motility component α is 55% or more and 85% or less, And the abundance ratio Rγ of the high mobility component γ is 1% or more and 10% or less. The polyethylene composition of claim 1.

4. A molded article of the polyethylene composition according to any one of claims 1 to 3.

5. The molded article according to claim 4, which is a film-like molded article.

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