Polyethylene resin compositions, films, and agricultural mulch films

Abstract

To provide a polyethylene resin composition that enables the continuous production of thin films while reducing environmental impact, and to provide a film and an agricultural mulch film.SOLUTION: A polyethylene resin composition according to the present invention comprises the following component (A) and component (B). Component (A): high-pressure low-density polyethylene derived from fossil fuels, fulfilling all of requirements (a1), (a2), and (a3): (a1) a melt mass flow rate (190°C, 2.16 kg) of 0.01-50 g / 10 min, (a2) a density of 900-935 kg / m3, and (a3) a molecular weight distribution (Mw / Mn) of 2-5, and component (B): high-pressure low-density polyethylene derived from biomass, fulfilling all of requirements (b1), (b2) and (b3): (b1) a melt mass flow rate (190°C, 2.16 kg) of 0.1-10 g / 10 min, (b2) a density of 900-935 kg / m3, and (b3) the ratio of MFR21.6 / MFR2.16 of 40 or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to polyethylene resin compositions, films, and agricultural mulch films. [Background technology]

[0002] In recent years, there has been a growing demand for the effective utilization of carbon resources from the perspective of reducing environmental impact. In the field of films, biomass-derived materials are attracting attention as part of the effective utilization of carbon resources. For example, Patent Document 1 describes a resin film made from a composition containing ethylene-α-olefin copolymer and biomass-derived low-density polyethylene as a film with excellent opening properties for packaging products. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-163631 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] For example, agricultural mulch films are required to be thin. However, when manufacturing resin films made from the above composition with a thin thickness, it is difficult to continuously form the film with the above composition, and the result is not entirely satisfactory.

[0005] This invention has been made in view of the above circumstances, and aims to provide a polyethylene resin composition, a film, and an agricultural mulch film that can be continuously manufactured into thin films while reducing environmental impact. [Means for solving the problem]

[0006] The polyethylene resin composition according to the present invention contains the following component (A) and component (B), with the total amount of component (A) and component (B) being 100% by mass, A polyethylene resin composition wherein the content of component (A) is 10 to 90% by mass, and the content of component (B) is 90 to 10% by mass. Component (A): Fossil fuel-derived high-pressure low-density polyethylene satisfying all of the following requirements (a1), (a2) and (a3) (a1): Melt mass flow rate (190°C, 2.16 kg) is 0.01 to 50 g / 10 min (a2): Density is 900 to 935 kg / m 3 (a3): Molecular weight distribution (Mw / Mn) is 2 to 5 Component (B): Biomass-derived high-pressure low-density polyethylene satisfying all of the following requirements (b1), (b2) and (b3) (b1): Melt mass flow rate (190°C, 2.16 kg) is 0.1 to 10 g / 10 min (b2): Density is 900 to 935 kg / m 3 (b3): MFRR is 40 or more (MFRR refers to melt mass flow rate at a temperature of 190°C and a load of 2.16 kg (MFR 2.16 ) versus the melt mass flow rate at a temperature of 190°C and a load of 21.6 kg (MFR 21.6 ) ratio (MFR 21.6 / MFR 2.16 ).)

[0007] The film according to the present invention has a layer made of the above-mentioned polyethylene resin composition.

[0008] The agricultural mulch film according to the present invention consists of the above-mentioned film. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a polyethylene resin composition, a film, and an agricultural mulch film that enable continuous film-forming of thin films while reducing environmental load. [Mode for Carrying Out the Invention]

[0010] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments.

[0011] The polyethylene resin composition according to the present embodiment contains, as component (A), a fossil fuel-derived high-pressure process low-density polyethylene, and as component (B), a biomass-derived high-pressure process low-density polyethylene.

[0012] <Component (A)> The fossil fuel-derived high-pressure process low-density polyethylene as component (A) is a polymer obtained by polymerizing a monomer containing ethylene derived from fossil fuels such as petroleum and natural gas.

[0013] The melt mass flow rate (MFR 2.16 ) of the fossil fuel-derived high-pressure process low-density polyethylene as component (A), measured under conditions of a temperature of 190°C and a load of 2.16 kg, is 0.01 to 50 g / 10 min. The aforementioned MFR 2.16 , from the viewpoint of stably forming a thin film, is preferably 0.05 g / 10 min or more, and more preferably 0.1 g / 10 min or more. Furthermore, the aforementioned MFR 2.16 , from the viewpoint of improving extrusion moldability, is preferably 10 g / 10 min or less, and more preferably 5 g / 10 min or less. In addition, the aforementioned MFR 2.16 is measured by the method specified in JIS K 7210-1-2014.

[0014] The density of the fossil fuel-derived high-pressure process low-density polyethylene as component (A) is 900 to 935 kg / m 3 . The aforementioned density, from the viewpoint of improving transparency and impact resistance, is preferably 930 kg / m 3 or less, and more preferably 925 kg / m 3 or less. Furthermore, the aforementioned density, from the viewpoint of improving rigidity, is preferably 905 kg / m 3 or more, and more preferably 910 kg / m 3This concludes the explanation. The density is measured using a sample that has undergone annealing as described in JIS K 6760-1995, in accordance with Method A (water displacement method) specified in JIS K 7112-1999.

[0015] The molecular weight distribution (Mw / Mn) of component (A), high-pressure low-density polyethylene derived from fossil fuels, is 2 to 5. From the viewpoint of enabling the continuous production of thin films, the molecular weight distribution (Mw / Mn) is preferably 2.5 or higher, and more preferably 3 or higher. Furthermore, from the viewpoint of further increasing the tensile strength, the molecular weight distribution (Mw / Mn) is preferably 4.5 or lower, and more preferably 4 or lower. Here, the molecular weight distribution (Mw / Mn) is the ratio of the weight-average molecular weight (Mw) of the resin composition to the number-average molecular weight (Mn) of high-pressure low-density polyethylene derived from fossil fuels. Mn and Mw are determined by gel permeation chromatography (GPC). GPC measurement is performed under the following conditions. The baseline on the chromatogram is defined based on the description in ISO 16014-1.

[0016] (Measurement conditions) Equipment: HLC-8321GPC / HT (manufactured by Tosoh Corporation) GPC columns: TOSOH TSKgelGMHHR-H(S)HT 7.8mm ID x 300mm (manufactured by Tosoh Corporation) 3 tubes Mobile phase: Orthodichlorobenzene (Wako Pure Chemical Industries, Ltd., special grade) with 0.1 w / V of BHT added. Flow rate: 1mL / min Column oven temperature: 140℃ Detection: Differential refractive index detector (RID) RID cell temperature: 140℃ Sample solution injection volume: 300 μL Sample solution concentration: 5 mg / mL GPC column calibration standards: Prepared by dissolving Tosoh standard polystyrene in 5 mL of orthodichlorobenzene (same composition as the mobile phase) at room temperature, according to the weights shown in Table 1.

[0017] [Table 1]

[0018] Component (A), fossil fuel-derived high-pressure low-density polyethylene, is an ethylene homopolymer produced by a high-pressure method in which raw materials containing ethylene derived from fossil fuels are supplied to a reactor and polymerized in the presence of a radical initiator.

[0019] In the high-pressure method, ethylene is polymerized under conditions of 1000 to 4000 atmospheres and 100 to 350°C, for example, using a multi-stage gas compressor. After that, residual monomers are separated and the mixture is cooled to obtain high-pressure low-density polyethylene.

[0020] Radical initiators include oxygen-based initiators such as organic peroxides, peroxyesters, dialkyl peroxides, or combinations thereof. Specific examples of radical initiators, though not limited to them, include t-butylperoxypivalate, di-t-butylperoxide (DTBP), t-butylperoxyacetate (TBPO), t-butylperoxy-2-ethylhexanoate, t-butylperoxyneodecanoate (PND), t-butylperoxyoctoate, and any two or more combinations thereof.

[0021] <Component B> Component (B), biomass-derived high-pressure low-density polyethylene, is a polymer obtained by polymerizing monomers containing ethylene derived from biomass such as plant residues and food waste. Biomass-derived ethylene can be obtained by known manufacturing methods. Since biomass-derived ethylene is used as the monomer raw material for the polymer, the polymerized high-pressure low-density polyethylene is biomass-derived. Note that the raw material monomer for polyethylene resin does not have to contain 100% by mass of biomass-derived ethylene. The monomer raw material for biomass-derived polyethylene resin may also contain monomers of ethylene derived from fossil fuels.

[0022] Examples of methods for producing biomass-derived ethylene include the method described in International Publication No. 2007 / 055361 or International Publication No. 2008 / 062709, which uses biomass-derived ethanol as a raw material; the method described in International Publication No. 2008 / 67627, which uses the residue of renewable natural raw materials as a raw material; the method described in International Publication No. 2009 / 070858, which uses ethanol produced by fermentation of sugars obtained by extraction and processing of biomass-derived raw materials; and the method described in International Publication No. 2016 / 184893 or International Publication No. 2016 / 184894, which produces ethylene by thermal cracking of bio-renewable supply materials.

[0023] The biomass content of component (B), biomass-derived high-pressure low-density polyethylene, is radiocarbon ( 14 This can be determined by measuring C). Atmospheric carbon dioxide contains, 14 Because it contains a certain percentage (105.5 pMC) of carbon, plants that take in carbon dioxide from the atmosphere to grow, such as corn, 14 It is also known that the carbon content is around 105.5 pMC. And in fossil fuels 14 It is also known that it contains almost no carbon. Therefore, the total carbon atoms in high-pressure low-density polyethylene are 14 By measuring the proportion of C, the biomass content of high-pressure low-density polyethylene can be calculated. 14 The C content is PE[ 14 When set to C, the biomass content of low-density polyethylene by high-pressure method PE bio This can be calculated as follows:

[0024] PE bio (%)=PE[ 14 C] / 105.5×100

[0025] Theoretically, if all ethylene and α-olefins derived from biomass are used as raw materials for high-pressure low-density polyethylene, the biomass content of the high-pressure low-density polyethylene will be 100%. Conversely, high-pressure low-density polyethylene produced solely from fossil fuel-derived raw materials will have a biomass content of 0%.

[0026] The biomass content of component (B), biomass-derived high-pressure low-density polyethylene, is preferably 5% or more, more preferably 10% or more, even more preferably 15% or more, and particularly preferably 20% or more.

[0027] The melt mass flow rate (MFR) of biomass-derived high-pressure low-density polyethylene, component (B), is measured under the conditions of a temperature of 190°C and a load of 2.16 kg. 2.16 The MFR is 0.1 to 10 g / 10 min. 2.16 From the viewpoint of enabling the continuous formation of thin films, the concentration is preferably 0.3 g / 10 min or more, and more preferably 0.5 g / 10 min or more. 2.16 From the viewpoint of improving impact resistance, the amount is preferably 7 g / 10 min or less, and more preferably 5 g / 10 min or less. 2.16 It is measured according to the method specified in JIS K 7210-1-2014.

[0028] The MFRR of component (B), biomass-derived high-pressure low-density polyethylene, is 40 or higher. The MFRR is calculated by melting the mass flow rate (MFR) at a temperature of 190°C and a load of 2.16 kg. 2.16 The melt mass flow rate (MFR) at a temperature of 190°C and a load of 21.6 kg for ) 21.6 ) ratio (MFR 21.6 / MFR 2.16 The MFRR is preferably 45 or higher, and more preferably 50 or higher, from the viewpoint of enabling the continuous production of thin films. Furthermore, from the viewpoint of improving impact resistance, it is preferably 120 or lower, and more preferably 100 or lower.

[0029] The density of component (B), biomass-derived high-pressure low-density polyethylene, is 900-935 kg / m³. 3 The density is preferably 930 kg / m³ from the viewpoint of improving impact resistance. 3 The following is more preferable: 925 kg / m 3 The following applies. Furthermore, from the viewpoint of increasing rigidity, the density is preferably 905 kg / m³. 3 The above is preferable, and more preferably 910 kg / m 3 This concludes the explanation. The density is measured using a sample that has undergone annealing as described in JIS K 6760-1995, in accordance with Method A (water displacement method) specified in JIS K 7112-1999.

[0030] Component (B), biomass-derived high-pressure low-density polyethylene, is an ethylene homopolymer produced by a high-pressure method in which biomass-derived ethylene-containing raw materials are supplied to a reactor and polymerized in the presence of a radical initiator.

[0031] In the high-pressure method, ethylene is polymerized under conditions of 1000 to 4000 atmospheres and 100 to 350°C, for example, using a multi-stage gas compressor. After that, residual monomers are separated and the mixture is cooled to obtain high-pressure low-density polyethylene.

[0032] Radical initiators include oxygen-based initiators such as organic peroxides, peroxyesters, dialkyl peroxides, or combinations thereof. Specific examples of radical initiators, though not limited to them, include t-butylperoxypivalate, di-t-butylperoxide (DTBP), t-butylperoxyacetate (TBPO), t-butylperoxy-2-ethylhexanoate, t-butylperoxyneodecanoate (PND), t-butylperoxyoctoate, and any two or more combinations thereof.

[0033] In this embodiment, the content of component (A) and component (B) in the polyethylene resin composition is such that, with the total amount of component (A) and component (B) being 100% by mass, the content of component (A) is 10 to 90% by mass and the content of component (B) is 90 to 10% by mass. If the content of component (A) is 90% by mass or less (and the content of component (B) is 10% by mass or more), the effect of reducing environmental burden is sufficient. Preferably, the content of component (A) is 30 to 70% by mass and the content of component (B) is 70 to 30% by mass.

[0034] The polyethylene resin composition according to this embodiment may contain other polymers, additives, etc., in addition to components (A) and (B). Examples of other polymers include high-density polyethylene, linear low-density polyethylene derived from fossil fuels, polypropylene resin, elastomers, etc. Examples of additives include antioxidants, anti-blocking agents, lubricants, antistatic agents, dispersants, processability improvers, pigments, weather stabilizers, ultraviolet absorbers, etc.

[0035] In one embodiment, the total amount of the polyethylene resin composition according to this embodiment is 100 parts by mass, and the sum of component (A) and component (B) is 50 parts by mass or more. Preferably, the sum of component (A) and component (B) is 70 parts by mass or more, and more preferably 80 parts by mass or more.

[0036] The polyethylene resin composition according to this embodiment is obtained by melt-kneading component (A), component (B), and other components as needed, using a known method. Known melt-kneading methods include, for example, mixing in a tumble mixer, Henschel mixer, etc., followed by further melt-kneading in a single-screw extruder, multi-screw extruder, etc., or melt-kneading in a kneader, Banbury mixer, etc.

[0037] [film] The film according to this embodiment is a film having a layer made of the polyethylene resin composition, and may be a single-layer film or a multilayer film. In the case of a multilayer film, layers other than the layer made of the polyethylene resin composition include layers made of polyolefin resins such as polyethylene resin and polypropylene resin, layers made of polyester resins such as polyethylene terephthalate and polybutylene terephthalate, layers made of polyamide resins such as nylon 6 and nylon 66, layers made of adhesives and adhesive resins, layers made of cellophane, paper, aluminum foil, etc.

[0038] The thickness of the film according to this embodiment is typically 1 to 100 μm, preferably 5 to 80 μm, and more preferably 10 to 50 μm. In the case of a multilayer film, the thickness of the layer made of the polyethylene resin composition is typically 30% or more of the total thickness of the multilayer film, and preferably 50% or more.

[0039] As a method for manufacturing the film according to this embodiment, known methods can be used, such as the inflation film molding method and the T die-cast film molding method. Furthermore, when producing a multilayer film, for example, the co-extrusion method, dry lamination method, wet lamination method, sand lamination method, hot melt lamination method, etc. can be used.

[0040] Furthermore, the film according to this embodiment may be a stretched film obtained by stretching an unstretched raw material obtained by pre-forming. Examples of stretching methods include uniaxial or biaxial stretching by roll stretching, tenter stretching, tubular stretching, etc.

[0041] The film according to this embodiment can be continuously produced as a thin film, making it suitable for use as agricultural mulch film and the like. It can also be used as packaging film for food and the like.

[0042] [Agricultural mulch film] The agricultural mulch film according to this embodiment consists of the film described above.

[0043] The agricultural mulch film according to this embodiment may be a single-layer film or a multi-layer film. Examples of multi-layer mulch films include those containing different types of pigments in each layer. Specifically, examples include those having a layer containing white pigment and a layer containing black pigment, or those having a layer containing silver pigment and a layer containing black pigment.

[0044] The agricultural mulch film according to this embodiment may be perforated or perforated as needed. Furthermore, the agricultural mulch film may be printed with information indicating planting locations, etc., as needed.

[0045] The polyethylene resin composition, film, and agricultural mulch film according to this embodiment are not limited to the above embodiment, and various modifications are possible without departing from the gist of the disclosure in this application. [Examples]

[0046] The present invention will be described in more detail below using examples and comparative examples, but the present invention is not limited to the following examples. The measured values ​​for each item in the examples and comparative examples were measured by the method described below.

[0047] (Physical property measurement method) [Meltmass flow rate (MFR, unit: g / 10 min) and MFRR] In accordance with JIS K 7210-1-2014, measurements were taken using Method A under the conditions of a temperature of 190°C and a load of 2.16 kg, and the value obtained was recorded as MFR. 2.16 Furthermore, measurements were taken under the conditions of a temperature of 190°C and a load of 21.6 kg, and the value was determined to be the MFR. 21.6 MFR 21.6 / MFR 2.16 The value was defined as MFRR.

[0048] [Density (d, unit: kg / m³)3 )] After performing the annealing treatment described in JIS K 6760-1995, measurements were taken according to Method A (water displacement method) described in JIS K 7112-1999.

[0049] [Molecular weight distribution (Mw / Mn)] Using the GPC method, the weight-average molecular weight (Mw) and number-average molecular weight (Mn) were measured under the following conditions, and the Mw / Mn ratio was determined. The baseline on the chromatogram was defined based on the description in ISO 16014-1. (Measurement conditions) Equipment: HLC-8321GPC / HT (manufactured by Tosoh Corporation) GPC columns: TOSOH TSKgelGMHHR-H(S)HT 7.8 ID x 300mm (manufactured by Tosoh Corporation) 3 tubes Mobile phase: Orthodichlorobenzene (Wako Pure Chemical Industries, Ltd., special grade) with 0.1 w / V of BHT added. Flow rate: 1mL / min Column oven temperature: 140℃ Detection: Differential refractive index detector (RID) RID cell temperature: 140℃ Sample solution injection volume: 300 μL Sample solution concentration: 5 mg / mL GPC column calibration standards: Prepared by dissolving Tosoh standard polystyrene in 5 mL of orthodichlorobenzene (same composition as the mobile phase) at room temperature, according to the weights shown in Table 2.

[0050] [Table 2]

[0051] [Continuous film formation capability] A polyethylene resin composition was supplied to an inflation film molding machine (manufactured by Placo Co., Ltd.) equipped with an extruder (screw diameter φ30 mm) and a die with a diameter of φ50 mm and a lip thickness of 2.0 mm. Single-layer films were formed under the following conditions. By changing the take-up speed, attempts were made to produce films with thicknesses of 30 μm, 20 μm, and 15 μm, respectively. A score of ○ was given if the film could be continuously formed for 10 m or more, and a score of × was given if it broke before reaching 10 m. In addition, if the film broke at a thickness of 20 μm, the evaluation at a thickness of 15 μm was not performed. ~Molding conditions~ • Die cylinder setting temperature: 150℃ • Extrusion conditions: 4.0-4.1 kg / hour • Blow-up ratio (BUR): 1.8 • Frost Rindistance (FLD): 155mm

[0052] (material) A-1: Fossil fuel-derived high-pressure low-density polyethylene, manufactured by Sumitomo Chemical Co., Ltd. Sumikasen (registered trademark) F200-0 (MFR 2.16 =2.2g / 10min, density=923kg / m 3 Molecular weight distribution Mw / Mn = 3.5, biomass content = 0%)

[0053] A-2: Fossil fuel-derived high-pressure low-density polyethylene, manufactured by Sumitomo Chemical Co., Ltd. Sumikasen (registered trademark) G201-F (MFR 2.16 =2.0g / 10min, density=919kg / m 3 Molecular weight distribution Mw / Mn = 10.2, biomass content = 0%)

[0054] B-1: Biomass-derived high-pressure low-density polyethylene, Braskem SEB853 (MFR 2.16 =2.7g / 10min, MFRR=55.8, density=923kg / m 3 Biomass content = 95%)

[0055] B-2: Biomass-derived high-pressure low-density polyethylene, Braskem SBC818 (MFR 2.16=8.3g / 10min, MFRR=35.4, density=918kg / m 3 Biomass content = 95%)

[0056] (Example 1) A composition obtained by mixing 50% by mass of material A-1 and 50% by mass of material B-1 was supplied to the aforementioned inflation film molding machine (manufactured by Placo Co., Ltd.) to attempt to produce films with thicknesses of 30 μm, 20 μm, and 15 μm, respectively. The results are shown in Table 3.

[0057] (Comparative Example 1) Film formation was attempted in the same manner as in Example 1, except that a composition obtained by mixing material A-1 (50% by mass) and material B-2 (50% by mass) was supplied to the extruder. The results are shown in Table 3.

[0058] (Comparative Example 2) Film formation was attempted in the same manner as in Example 1, except that a composition of material A-2 (50% by mass) and material B-1 (50% by mass) was supplied to the extruder. The results are shown in Table 3. Note that the film broke at a thickness of 20 μm, so evaluation at a thickness of 15 μm was not performed.

[0059] (Comparative Example 3) Film formation was attempted in the same manner as in Example 1, except that a composition of material A-2 (50% by mass) and material B-2 (50% by mass) was supplied to the extruder. The results are shown in Table 3. Note that the film broke at a thickness of 20 μm, so evaluation at a thickness of 15 μm was not performed.

[0060] [Table 3]

[0061] The results above demonstrate that the polyethylene resin composition of the present invention can be used to continuously produce thin films. Furthermore, because it uses biomass-derived high-pressure low-density polyethylene, carbon resources can be effectively utilized, and the environmental burden can be reduced.

Claims

1. The following components (A) and (B) are contained, and the total amount of components (A) and (B) is 100% by mass. The content of component (A) is 10 to 90% by mass, and the content of component (B) is 90 to 10% by mass. A polyethylene resin composition in which, with 100 parts by mass of the entire polyethylene resin composition, the sum of component (A) and component (B) is 70 parts by mass or more. Component (A): Fossil fuel-derived high-pressure low-density polyethylene that satisfies all of the following requirements (a1), (a2), and (a3). (a1): Meltmass flow rate (190°C, 2.16 kg) is 0.01 to 50 g / 10 min (a2): Density 900-935 kg / m³ ３ (a3): Molecular weight distribution (Mw / Mn) is 2-5 Component (B): Biomass-derived high-pressure low-density polyethylene that satisfies all of the following requirements (b1), (b2), and (b3). (b1): Meltmass flow rate (190°C, 2.16 kg) 0.1-10 g / 10 min (b2): Density of 900-935 kg / m³ ３ (b3): ​​MFRR is 40 or higher (MFRR is the melt mass flow rate (MFR) at a temperature of 190°C and a load of 2.16 kg) ２．１６ ) Melt mass flow rate (MFR) at a temperature of 190°C and a load of 21.6 kg ２１．６ ) ratio (MFR ２１．６ / MFR ２．１６ )

2. A film having a layer made of the polyethylene resin composition described in claim 1.

3. Agricultural mulch film comprising the film described in claim 2.

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