JP6753345B2 - Polyethylene resin composition for telescopic rod net and its molded product - Google Patents

Description

The present invention relates to a polyethylene resin composition for a telescopic rod net and a molded product thereof. More specifically, the present invention is excellent in molding processability, particularly adhesive strength between material strands constituting the net, and a fused portion in a stretching step during net molding. The present invention relates to a polyethylene resin composition for a telescopic rod net capable of stable production with little peeling, and a molded product made of the same.

Conventionally, a telescopic rod net typified by a so-called "mandarin orange net" for containing fruits such as tangerines is required to have flexibility, elasticity, and breaking strength. In order to satisfy the performance, strong adhesive strength between the extruded material strands is indispensable when forming the telescopic rod net.
The telescopic rod net is a molten strand whose extruded material is thin, and when the strands come into contact with each other, a contact portion is formed to form a network structure. At that time, in order to form a strong network structure, it is preferable that the molten strands are in strong contact with each other. Further, in order to develop the elasticity of the telescopic rod net, the net undergoes strong stretching once in the net forming process, but if the material strength of the strand is low or the strength of the contact portion of the strand is weak, the net is formed. There is a problem that it breaks and a hole is opened in the middle of the process.

Patent Document 1 (Japanese Patent Laid-Open No. 7-30216) discloses a polyethylene resin composition for an extrusion net, which comprises 80 to 95 parts by weight of branched low-density polyethylene mixed with 20 to 5 parts by weight of linear low-density polyethylene. It is said that the strength and elasticity are superior to those of the conventional ethylene-vinyl acetate copolymer (EVA).
However, when branched low-density polyethylene is used as the main component, the melting point of the composition tends to be higher than that of EVA, so that the adhesion between the molten strands when forming the net structure becomes insufficient, and the contact portion is fused. The strength may be low. In addition, since the composition is harder than the one containing EVA, the feel of the product may be hard and the contents may be damaged.

Special Fair 7-30216 Gazette

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a polyethylene resin composition for a telescopic rod net having excellent molding processability and excellent flexibility, and a molded product thereof. In particular, the present invention provides a polyethylene resin composition for a telescopic rod net, which has excellent adhesive strength between material strands constituting a net, less peeling of a fused portion in a stretching process during net molding, and stable production, and a molded product made of the same. The task is to do.

As a result of intensive research to solve the above problems, the present inventors have made a specific polyethylene having a specific long-chain branched structure and an ethylene-vinyl acetate copolymer having a specific index in a predetermined ratio. It has been found that the mixed polyethylene resin composition solves the above-mentioned problems and exhibits good properties, and based on these findings, the present invention has been completed.

The polyethylene resin composition for a telescopic rod net of the present invention has 10 to 30% by mass of polyethylene (A) having the following properties (a1) to (a4) and ethylene-vinyl acetate having the following properties (b1) to (b2). It is characterized by containing 70 to 90% by mass of the copolymer (B) and having the following characteristics (I) to (V).
Characteristic (a1): The melt flow rate (MFR) measured at a temperature of 190 ° C. and a load of 2.16 kg is 0.1 to 1.5 g / 10 minutes.
Characteristic (a2): The density is 0.9000 to 0.930 g / cm ³ .
Characteristic (a3): Molecular weight of branch index (g') measured by a gel permeation chromatography (GPC) measuring device equipped with a differential refractometer, a viscosity detector and a light scattering detector as detectors, with a molecular weight of 100,000 to 1,000,000. The lowest value (gc) between them is 0.40 to 0.85.
Property (a4): Percentage of components whose molecular weight is equal to or greater than the weight average molecular weight among the components eluted at a temperature or lower at which the elution amount determined from the integrated elution curve measured by cross fractionation chromatography (CFC) is 50% by mass (W). ₂ ) and the sum of the proportions (W ₃ ) of the components whose molecular weight is less than the weight average molecular weight among the components eluted at a temperature higher than the temperature at which the elution amount obtained from the integrated elution curve is 50% by mass (W ₂ + W ₃ ). However, it is 40 to 80% by mass.
Characteristic (b1): MFR is 0.1 to 1.5 g / 10 minutes.
Property (b2): The vinyl acetate content is 5 to 20% by mass.
Characteristic (I): MFR is 0.1 to 1.5 g / 10 minutes.
Characteristic (II): The flexural modulus at 23 ° C. is 80 to 250 MPa.
Characteristic (III): The melting tension at 190 ° C. is 75 mN or more.
Characteristic (IV): The tensile impact strength at 23 ° C. is 300 KJ / m ² or more.
Characteristic (V): One of the melting point peaks measured by a differential scanning calorimeter (DSC) is 106 ° C. or lower.

The molded product of the present invention is characterized by being composed of the polyethylene resin composition for a telescopic rod net.

The polyethylene resin composition for a telescopic rod net of the present invention is excellent in molding processability and flexibility, and can provide a material particularly useful as a material for a telescopic rod net. In particular, the present invention provides a polyethylene resin composition for a telescopic rod net, which has excellent adhesive strength between material strands constituting a net, less peeling of a fused portion in a stretching process during net molding, and stable production, and a molded product made of the same. can do.

The polyethylene resin composition for a telescopic rod net of the present invention has 10 to 30% by mass of polyethylene (A) having the following properties (a1) to (a4) and ethylene-vinyl acetate having the following properties (b1) to (b2). It is characterized by containing 70 to 90% by mass of the copolymer (B) and having the following characteristics (I) to (V).
Characteristic (a1): The melt flow rate (MFR) measured at a temperature of 190 ° C. and a load of 2.16 kg is 0.1 to 1.5 g / 10 minutes.
Characteristic (a2): The density is 0.9000 to 0.930 g / cm ³ .
Characteristic (a3): Molecular weight of branch index (g') measured by a gel permeation chromatography (GPC) measuring device equipped with a differential refractometer, a viscosity detector and a light scattering detector as detectors, with a molecular weight of 100,000 to 1,000,000. The lowest value (gc) between them is 0.40 to 0.85.
Property (a4): Percentage of components whose molecular weight is equal to or greater than the weight average molecular weight among the components eluted at a temperature or lower at which the elution amount determined from the integrated elution curve measured by cross fractionation chromatography (CFC) is 50% by mass (W). ₂ ) and the sum of the proportions (W ₃ ) of the components whose molecular weight is less than the weight average molecular weight among the components eluted at a temperature higher than the temperature at which the elution amount obtained from the integrated elution curve is 50% by mass (W ₂ + W ₃ ). However, it is 40 to 80% by mass.
Characteristic (b1): MFR is 0.1 to 1.5 g / 10 minutes.
Property (b2): The vinyl acetate content is 5 to 20% by mass.
Characteristic (I): MFR is 0.1 to 1.5 g / 10 minutes.
Characteristic (II): The flexural modulus at 23 ° C. is 80 to 250 MPa.
Characteristic (III): The melting tension at 190 ° C. is 75 mN or more.
Characteristic (IV): The tensile impact strength at 23 ° C. is 300 KJ / m ² or more.
Characteristic (V): One of the melting point peaks measured by a differential scanning calorimeter (DSC) is 106 ° C. or lower.

Hereinafter, the polyethylene resin composition of the present invention and its uses will be described in detail for each item. Further, in the present specification, "~" indicating a numerical range is used to mean that the numerical values described before and after the numerical range are included as the lower limit value and the upper limit value.

1. Polyethylene (A)
The polyethylene (A) used in the present invention needs to satisfy the following properties (a1) to (a4).
Characteristic (a1): The melt flow rate (MFR) measured at a temperature of 190 ° C. and a load of 2.16 kg is 0.1 to 1.5 g / 10 minutes.
Characteristic (a2): The density is 0.9000 to 0.930 g / cm ³ .
Characteristic (a3): Molecular weight of branch index (g') measured by a gel permeation chromatography (GPC) measuring device equipped with a differential refractometer, a viscosity detector and a light scattering detector as detectors, with a molecular weight of 100,000 to 1,000,000. The lowest value (gc) between them is 0.40 to 0.85.
Property (a4): Percentage of components whose molecular weight is equal to or greater than the weight average molecular weight among the components eluted at a temperature or lower at which the elution amount determined from the integrated elution curve measured by cross fractionation chromatography (CFC) is 50% by mass (W). ₂ ) and the sum of the proportions (W ₃ ) of the components whose molecular weight is less than the weight average molecular weight among the components eluted at a temperature higher than the temperature at which the elution amount obtained from the integrated elution curve is 50% by mass (W ₂ + W ₃ ). However, it is 40 to 80% by mass.

1-1. Characteristic (a1) MFR
The MFR of polyethylene (A) is 0.1 to 1.5 g / 10 minutes, preferably 0.1 to 0.5 g / 10 minutes.
When the MFR is 0.1 g / 10 minutes or more, the molding processability of the polyethylene resin composition for the telescopic rod net, particularly the melt fluidity, is stable, and when the MFR is 1.5 g / 10 minutes or less, the impact strength of the molded product is good. It becomes.
In this specification, the MFR of the ethylene polymer and the polyethylene resin composition conforms to JIS K7210 "Test method for melt mass flow rate (MFR) and melt volume flow rate (MVR) of plastic-thermoplastic plastic". Then, it means the value when measured under the condition of 190 ° C. and 2.16 kg load.
The MFR of polyethylene (A) can be adjusted by changing the amount of chain transfer agent (hydrogen, etc.) coexisting during ethylene polymerization or by changing the polymerization temperature, and the amount of hydrogen is increased. Alternatively, it can be increased by increasing the polymerization temperature.

1-2. Density characteristics (a2) Density Polyethylene (A) is, 0.900 g / cm ³ or more 0.930 g / cm ³ or less, preferably 0.915~0.924g / cm ^3.
When the density is in this range, the balance between the rigidity and the impact resistance of the molded product is excellent. In addition, when the density is 0.900 g / cm ³ or more, the rigidity is improved, the stiffness of the product is suppressed from becoming low, and when a heavy object is put in, the weight cannot be supported and the product stretches and breaks. Can be suppressed. Further, when the density is 0.930 g / cm ³ or less, it is possible to prevent the product from becoming too stiff and to suppress damage to the contents.
In this specification, the density of polyethylene refers to a value measured by the following method.
The density can be adjusted, for example, by changing the amount of α-olefin copolymerized with ethylene, and can be reduced by increasing the amount of α-olefin.

The density can be measured by the following method. That is, polyethylene pellets are hot-pressed to prepare a press sheet having a thickness of 2 mm, the sheet is placed in a beaker having a capacity of 1000 ml, filled with distilled water, covered with a watch glass, and heated with a mantle heater. After boiling the distilled water for 60 minutes, place the beaker on a wooden table and let it cool. At this time, the boiling distilled water after boiling for 60 minutes is set to 500 ml, and the time until the room temperature is adjusted so as not to be 60 minutes or less. In addition, the test sheet is immersed in a substantially central portion of water so as not to come into contact with the beaker and the water surface. After annealing the sheet under the conditions of 23 ° C. and 50% humidity within 16 hours or more and 24 hours or less, the sheet is punched to a length and width of 2 mm, and at a test temperature of 23 ° C., JIS K7112 "Plastic-non-foamed plastic density" And the measurement method of specific gravity ”.

1-3. Characteristic (a3) gc
Polyethylene (A) has a molecular weight of 100,000 to 100 in branch index (g') measured by a gel permeation chromatography (GPC) measuring device equipped with a differential refractometer, a viscosity detector and a light scattering detector as detectors. The lowest value (gc) among 10,000 is 0.40 to 0.85, preferably 0.50 to 0.80, more preferably 0.50 to 0.77, and particularly preferably 0.51 to 0. 75. When the g _C value is 0.85 or less, the effect of improving the molding processability when blended with the polyolefin resin can be satisfactorily exhibited. When the g _C value is 0.40 or more, the molding processability of the polyolefin resin is lowered, but the impact strength is good, and the desired transparency tends to be obtained.
In the present invention, the g _C value of polyethylene (A) is an evaluation index of the amount of long chain branching using the molecular weight distribution curve and the branching index (g') calculated from the following GPC-VIS measurement.
The minimum value (gc) of the branching index g'with a molecular weight of 100,000 to 1,000,000 can be set in a predetermined range mainly by selecting a polymerization catalyst and polymerization conditions, and is preferably a specific value. By using a metallocene catalyst, it can be within a predetermined range.

The lowest value (gc) of the branching index g'with a molecular weight between 100,000 and 1,000,000 reflects that the polyethylene component (b) has a specific long-chain branched structure. Then, for example, a "catalyst containing a transition metal" capable of introducing a long-chain branch into an ethylene-based polymer is a metallocene-based catalyst in which a very small number of long-chain branches are introduced into a polyethylene molecular chain in a phillips-based catalyst or the like. But long-chain branching can be introduced. Since this long-chain branch is usually contained in a very small amount, it is difficult to quantitatively analyze the structure, but even one or less per 10,000 main chain carbons has a significant effect on the melt properties of polyethylene and therefore the moldability. As a mechanism for forming a long chain branch by these catalysts, examples reported by publicly known papers can be referred to. In the case of a Phillips-based catalyst, the long-chain branching formation mechanism is that polyethylene (macromer) having a terminal vinyl group is generated by chain transfer to ethylene, and then the macromonomer is a chromium-carbon bond of the growth chain at the neighboring active site. It is believed that polyethylene with long-chain branches is produced when a chain transfer reaction to ethylene occurs after reinsertion into ethylene, further insertion of ethylene, and continued growth reaction. Furthermore, regarding the method of controlling the amount of long-chain branching of the ethylene-based polymer by these catalysts, considering the mechanism that long-chain branching is generated by reinsertion of the macromonomer, the active points exist at close distances. If this is done, macromonomers generated at other active points can be easily inserted, and the amount of long-chain branching increases.
As a method for controlling the amount of long-chain branching, for example, the amount of long-chain branching of the ethylene-based polymer increases due to the presence of the active points of the catalyst at close distances, or a carrier having a small surface surface is used. By increasing the amount of active species atoms supported per unit surface surface by increasing the amount of active species atoms supported, the amount of long-chain branches of the ethylene-based polymer tends to increase, and the chromium catalyst In the case of, the amount of long-chain branching can be increased as the activation temperature is raised.

[Branch structure analysis by GPC-VIS]
As a GPC apparatus equipped with a differential refractometer (RI) and a viscosity detector (Viscometer), the Alliance GPCV2000 manufactured by Waters can be used. Further, as the light scattering detector, DAWN-E manufactured by Multi-angle Laser Light Scattering Detector (MALLS) Wyatt Technology can be used. The detectors are connected in the order of MALLS, RI, and Viscometer. The mobile phase solvent is 1,2,4-trichlorobenzene (antioxidant Irganox 1076 added at a concentration of 0.5 mg / mL). The flow rate is 1 mL / min. The column can be used by connecting two GMHHR-H (S) HTs manufactured by Tosoh Corporation. The temperature of the column, the sample injection part and each detector is 140 ° C. The sample concentration is 1 mg / mL. The injection volume (sample loop volume) is 0.2175 mL. The data processing software ASTRA (version 4.73.04) attached to MALLS was used to obtain the absolute molecular weight (M) obtained from MALLS, the squared radius of inertia (Rg), and the ultimate viscosity ([η]) obtained from Viscometer. , Perform the calculation with reference to the following documents.
References:
1. Developments in polimer cultivation, vol. 4. Essex: Applied Science; 1984. Chapter1.
2. Polymer, 45, 6495-6505 (2004)
3. Macromolecules, 33, 2424-2436 (2000)
4. Macromolecules, 33, 6945-6952 (2000)

[Calculation of branching index (g _C ), etc.]
The branching index (g') is calculated as a ratio (ηbranch / ηlin) between the ultimate viscosity (ηbranch) obtained by measuring a sample with the Viscometer and the ultimate viscosity (ηlin) obtained by separately measuring a linear polymer. To do.
When a long-chain branch is introduced into a polymer molecule, the radius of inertia is smaller than that of a linear polymer molecule of the same molecular weight. Since the ultimate viscosity decreases as the radius of inertia decreases, the ratio (ηbranch / ηlin) of the ultimate viscosity (ηbranch) of the branched polymer to the ultimate viscosity (ηlin) of the linear polymer having the same molecular weight decreases as the long-chain branching is introduced. It will become. Therefore, when the branching index (g'= ηbranch / ηlin) becomes a value smaller than 1, it means that a branch is introduced, and as the value becomes smaller, the introduced long-chain branch increases. Means that. In particular, in the present invention, as the absolute molecular weight obtained from MALLS, the lowest value of g'at a molecular weight of 100,000 to 1,000,000 is calculated as g _C. Here, as the linear polymer, linear polyethylene Standard Reference Material 1475a (National Institute of Standards & Technology) can be used.

1-4. Characteristics (a4) W ₂ + W ₃
Polyethylene (A) is an ethylene / α-olefin copolymer having a molecular weight among the components eluted at a temperature or lower at which the elution amount obtained from the integrated elution curve measured by cross fractionation chromatography (CFC) is 50% by mass or less. The molecular weight of the components eluted at a temperature higher than the temperature at which the elution amount obtained from the integral elution curve and the ratio of the components (W ₂ ) equal to or more than the weight average molecular weight of the above is 50% by mass is the common weight of the ethylene / α-olefin. The sum (W ₂ + W ₃ ) of the proportions of components (W ₃ ) less than the weight average molecular weight of the coalescence is 40 to 80% by mass, preferably 41 to 70% by mass, more preferably more than 43% by mass and 56% by mass. Less than, particularly preferably more than 45% by weight and less than 56% by weight.
When the W ₂ + W ₃ value is 40% by mass or more, the proportion of the low-density high-molecular-weight component that effectively improves the impact strength of the polyethylene resin increases, and the high that effectively acts to improve the rigidity of the polyethylene resin. The density low molecular weight component tends to increase.
On the other hand, when the W ₂ + W ₃ value is 80% by mass or less, the balance between the contents of the high-density low-molecular-weight component and the low-density high-molecular-weight component is excellent, and the effect of modifying the physical properties of the polyethylene resin is exhibited as expected. The dispersibility of the high-density low-molecular-weight component and the low-density high-molecular-weight component is improved, desired transparency is obtained, and gel generation tends to be suppressed.
The value of W ₂ + W ₃ can be set within a predetermined range mainly by selecting a polymerization catalyst and polymerization conditions, and preferably within a predetermined range by using a specific metallocene catalyst. Can be done.
The polymerization catalyst and polymerization conditions for controlling the value of W ₂ + W ₃ of polyethylene (A) are not particularly limited as long as a polymer corresponding to the range of the values can be produced, but the value of polyethylene (A) is not particularly limited. Examples of technologies suitable for production and satisfying economic efficiency at the industrial level include metallocene catalysts and post-metallocene catalysts, among which long-chain branched catalysts such as metallocene catalysts that generate macromers and metallocene catalysts that copolymerize macromers are used. A metallocene catalyst is preferred.

[CFC measurement conditions]
The cross fractionation chromatograph (CFC) comprises a temperature-increasing elution fractionation (TREF) section for crystalline fractionation and a gel permeation chromatography (GPC) section for molecular weight fractionation.
The analysis using this CFC is performed as follows.
First, a polymer sample of an ethylene / α-olefin copolymer was completely dissolved in orthodichlorobenzene (ODCB) containing 0.5 mg / mL dibutylhydroxytoluene (BHT) at 140 ° C., and then this solution was used as a sample of the apparatus. The polymer sample is crystallized by injecting it into a TREF column (a column filled with an inert glass bead carrier) kept at 140 ° C. through a loop and gradually cooling to a predetermined first elution temperature. After holding at a predetermined temperature for 30 minutes, the ODCB is passed through a TREF column, so that the eluted component is injected into the GPC section to separate the molecular weight, and an infrared detector (MIRAN 1A IR detector manufactured by FOXBORO) is used. A chromatogram can be obtained with a measurement wavelength of 3.42 μm). During that time, the temperature is raised to the next elution temperature in the TREF section, and after a chromatogram of the first elution temperature is obtained, the elution component at the second elution temperature is injected into the GPC section. Hereinafter, by repeating the same operation, a chromatogram of the elution component at each elution temperature can be obtained.

The CFC measurement conditions are as follows.
Equipment: CFC-T102L manufactured by Dia Instruments
GPC column: Showa Denko AD-806MS (3 connected in series)
Solvent: ODCB
Sample concentration: 3 mg / mL
Injection volume: 0.4 mL
Crystallization rate: 1 ° C / min Solvent flow rate: 1 mL / min GPC measurement time: 34 minutes Stable time after GPC measurement: 5 minutes Elution temperature: 0,5,10,15,20,25,30,35,40,45 , 49, 52, 55, 58, 61, 64, 67, 70, 73, 76, 79, 82, 85, 88, 91, 94, 97, 100, 102, 120, 140

[Data analysis]
From the chromatogram of the elution component at each elution temperature obtained by the measurement, the elution amount (proportional to the area of the chromatogram) standardized so that the total sum is 100% can be obtained.
In addition, an integrated elution curve for elution temperature is calculated. The differential elution curve is obtained by differentiating this integral elution curve with temperature.
In addition, the molecular weight distribution can be obtained from each chromatogram by the following procedure. The conversion from the retention volume to the molecular weight is performed using a calibration curve based on standard polystyrene prepared in advance. The standard polystyrenes used are all the following brands manufactured by Tosoh Corporation.
F380, F288, F128, F80, F40, F20, F10, F4, F1, A5000, A2500, A1000.
A calibration curve is created by injecting 0.4 mL of a solution dissolved in ODCB (containing 0.5 mg / mL BHT) so that each is 0.5 mg / mL.
For the calibration curve, a cubic expression obtained by approximation by the least square method is used.
For conversion to molecular weight, a general-purpose calibration curve is used with reference to "Size Exclusion Chromatography" (Kyoritsu Shuppan) by Sadao Mori. The following numerical values are used for the viscosity formula [η] = K × M ^α used at that time.
PS: K = 1.38 × 10 ^-4 , α = 0.7
PE: K = 3.92 × 10 ^-4 , α = 0.733
In the chromatogram at the first elution temperature, the peak due to BHT added to the solvent and the low molecular weight side of the elution component may overlap. In that case, a baseline is drawn to determine the section for obtaining the molecular weight distribution.
Further, as shown in Table 1 below, the weight average molecular weight of whole (overall) is obtained from the elution ratio (mass% in the table) and the weight average molecular weight (Mw in the table) at each elution temperature.

In addition, from the molecular weight distribution and elution amount at each elution temperature, the literature (S. Nakano, Y. Goto, "Development of automatic Cross Fractionation: Combination of Crystallizability Fractionation Fractionation Fractionation According to the method of .26, pp. 4217-4231 (1981)), a graph (contour diagram) showing the elution amount with respect to the elution temperature and the molecular weight as contour lines is obtained.
The following component amounts are obtained using the above contour diagram.
W ₁ : Percentage of components whose molecular weight is less than the weight average molecular weight of the ethylene / α-olefin copolymer among the components eluted at a temperature or lower at which the elution amount obtained from the integral elution curve is 50% by mass or less.
W ₂ : Percentage of components whose molecular weight is equal to or greater than the weight average molecular weight of the ethylene / α-olefin copolymer among the components eluted at a temperature or lower at which the elution amount determined from the integral elution curve is 50% by mass or less.
W ₃ : Percentage of components whose molecular weight is less than the weight average molecular weight of the ethylene / α-olefin copolymer among the components eluted at a temperature higher than the temperature at which the elution amount obtained from the integral elution curve is 50% by mass.
W ₄ : Percentage of components whose molecular weight is equal to or greater than the weight average molecular weight of the ethylene / α-olefin copolymer among the components eluted at a temperature higher than the temperature at which the elution amount obtained from the integral elution curve is 50% by mass.
In addition, W ₁ + W ₂ + W ₃ + W ₄ = 100.

1-5. Property (a5) Flexural modulus at 23 ° C. Polyethylene (A) preferably satisfies the property (a5) in addition to the above properties (a1) to (a4).
The flexural modulus of polyethylene (A) at 23 ° C. is preferably 80 MPa or more and 450 MPa or less, and more preferably 100 MPa or more and 350 MPa or less. When the flexural modulus is 80 MPa or more, the rigidity of the product is good, and it is possible to suppress breakage when a heavy product is put in. On the other hand, when the flexural modulus is 450 MPa or less, it is possible to prevent the product from becoming too stiff and to prevent damage to the contents.
Here, the flexural modulus at 23 ° C. is a value measured by JIS K7171 by cutting out a test piece having a thickness of 10 mm × 80 × 4 mmt from a 4 mm thick molded sheet prepared by compression molding in accordance with JIS K6922-2. ..

2. Ethylene-vinyl acetate copolymer (B)
The ethylene-vinyl acetate copolymer (B) needs to satisfy the following properties (b1) and (b2).
Characteristic (b1): Melt flow rate (MFR) at a temperature of 190 ° C. and a load of 2.16 kg is 0.1 to 1.5 g / 10 minutes.
Property (b2): The vinyl acetate content is 5% by mass or more and 20% by mass or less.

2-1. Characteristic (b1) MFR
The MFR of the ethylene-vinyl acetate copolymer (B) is 0.1 to 1.5 g / 10 minutes, preferably 0.1 to 1.0 g / 10 minutes.
When the MFR is 0.1 g / 10 minutes or more, the molding processability of the polyethylene resin composition for the telescopic rod net, particularly the melt fluidity, is stable, and when the MFR is 1.5 g / 10 minutes or less, the impact strength of the molded product is good. It becomes.
In this specification, the MFR of the ethylene polymer and the polyethylene resin composition conforms to JIS K7210 "Test method for melt mass flow rate (MFR) and melt volume flow rate (MVR) of plastic-thermoplastic plastic". Then, it means the value when measured under the condition of 190 ° C. and 2.16 kg load.
The adjustment of MFR can be increased by increasing the MFR of the base polyethylene.

2-2. Characteristics (b2) Vinyl Acetate Content The vinyl acetate content of the ethylene-vinyl acetate copolymer (B) is 5% by mass or more and 20% by mass or less, preferably 5% by mass or more and 15% by mass or less. If it is 5% by mass or more, the melting point becomes low, the fusion between the nets proceeds well, the fusion strength can be increased, the rigidity of the product becomes low, and it is possible to prevent the product from becoming too stiff. Further, when it is 15% by mass or less, EVA can be easily produced. The vinyl acetate content is a value measured in accordance with JIS K7192 "Plastic-Ethylene Vinyl Acetate Resin (EVAC) -Vinyl Acetate Content Measurement Method".

2-3. Property (b3) Flexural modulus at 23 ° C. The ethylene-vinyl acetate copolymer (B) preferably satisfies the property (b3) in addition to the above properties (b1) to (b2).
The ethylene-vinyl acetate copolymer (B) preferably has a flexural modulus of 50 MPa or more and 140 MPa or less at 23 ° C. When the flexural modulus is 50 MPa or more, the rigidity of the product is good, and it is possible to suppress breakage when a heavy product is put in. On the other hand, when the flexural modulus is 140 MPa or less, it is possible to prevent the product from becoming too stiff and to prevent damage to the contents.
Here, the flexural modulus at 23 ° C. is a value measured by the same method as that for polyethylene (A).

3. Composition of Polyethylene Resin Composition for Telescopic Rod Net The polyethylene resin composition for telescopic rod net of the present invention contains polyethylene (A) and an ethylene-vinyl acetate copolymer (B). In terms of product rigidity (product stiffness), the composition ratio of polyethylene (A) is 10% by mass or more and 30% by mass or less, and the composition ratio of ethylene-vinyl acetate copolymer (B) is 70% by mass. As mentioned above, it is 90% by mass or less. The composition ratio of polyethylene (A) is preferably 10% by mass or more and 25% by mass or less, and the composition ratio of ethylene-vinyl acetate copolymer (B) is 75% by mass or more and 90% by mass or less, more preferably polyethylene (A). It is desirable that the composition ratio of) is 10% by mass or more and 20% by mass or less, and the composition ratio of the ethylene-vinyl acetate copolymer (B) is 80% by mass or more and 90% by mass or less.

4. Characteristics of Polyethylene Resin Composition for Telescopic Rod Net The polyethylene resin composition for telescopic rod net of the present invention satisfies the following characteristics (I) to (V).
Characteristic (I): MFR is 0.1 to 1.5 g / 10 minutes.
Characteristic (II): The flexural modulus at 23 ° C. is 80 to 250 MPa.
Characteristic (III): The melting tension at 190 ° C. is 75 mN or more.
Characteristic (IV): The tensile impact strength at 23 ° C. is 300 KJ / m ² or more.
Characteristic (V): One of the melting point peaks measured by a differential scanning calorimeter (DSC) is 106 ° C. or lower.

4-1. Characteristic (I) MFR
The polyethylene resin composition for a telescopic rod net of the present invention has an MFR of 0.1 g / 10 minutes or more and 1.5 g / 10 minutes or less, preferably 0.2 g / 10 minutes or more and 0.9 g / 10 minutes or less. ..
When the MFR is in this range, the molding stability in each step during manufacturing is excellent. When the MFR is 0.1 g / 10 minutes or more, the extrusion load becomes small and the discharge of the extruder increases, and when the MFR is 1.5 g / 10 minutes or less, breakage in the drawing step can be suppressed.
The MFR refers to a value measured by the above-mentioned MFR measuring method.
The MFR can be adjusted, for example, by adjusting the blending ratio of polyethylene (A) and ethylene-vinyl acetate copolymer (B).

4-2. Characteristic (II) Flexural modulus at 23 ° C. The polyethylene resin composition for a telescopic rod net of the present invention has a flexural modulus at 23 ° C. of 80 MPa or more and 250 MPa or less, preferably 100 MPa or more and 200 MPa or less. When the flexural modulus is 80 MPa or more, the rigidity of the product is good, and it is possible to suppress breakage when a heavy product is put in. On the other hand, when the flexural modulus is 250 MPa or less, it is possible to prevent the product from becoming too stiff and to prevent damage to the contents.
Here, the flexural modulus at 23 ° C. is a value measured by JIS K7171 by cutting out a test piece having a thickness of 10 mm × 80 × 4 mmt from a 4 mm thick molded sheet prepared by compression molding in accordance with JIS K6922-2. ..
The flexural modulus can be adjusted by increasing or decreasing the density of polyethylene (A) or increasing or decreasing the amount of vinyl acetate of the ethylene-vinyl acetate copolymer (B). Further, for example, polyethylene ( This can be done by adjusting the blending ratio of A) and the ethylene-vinyl acetate copolymer (B).

4-3. Characteristics (III) Melt tension (MT) at 190 ° C.
The polyethylene resin composition for a telescopic rod net of the present invention has a melt tension at 190 ° C. of 75 mN or more, preferably 120 mN or more. When the melt tension is 75 mN or more, the adhesion of the strands in contact with each other becomes good at the time of manufacturing, and it is possible to prevent the adhesion point from coming off and a hole from being formed in the net. There is no particular upper limit, but it is usually 250 mN or less.
Here, as the melt tension, a capillograph 1B manufactured by Toyo Seiki Seisakusho Co., Ltd. is used to extrude the molten resin under the conditions of a temperature of 190 ° C., an orifice diameter of 2.095 mm, an orifice length of 8.0 mm, and an extrusion speed of 15 mm / min, and a winder. It is a load when wound at a speed of 3.8 m / min, and the unit is mN.
Further, the melt tension can be adjusted by lowering the MFR or adjusting the blending ratio of the polyethylene (A) and the ethylene-vinyl acetate copolymer (B).

4-4. Characteristics (IV) Tension Impact Strength at 23 ° C The polyethylene resin composition for a telescopic rod net of the present invention has a tensile impact strength at 23 ° C of 300 KJ / m ² or more, preferably 320 KJ / m ² or more, although no upper limit is provided. Usually, it is 1,000 KJ / m ² or less. When the tensile impact strength is 300 KJ / m ² or more, it is possible to suppress the occurrence of breakage in the stretching step.
Here, the tensile impact strength is a value measured by ISO 8256 by cutting out a test piece having a thickness of 10 mm × 80 × 4 mmt from a 4 mm thick molded sheet prepared by compression molding in accordance with JIS K6922-2.
The tensile impact strength can increase or decrease the MFR and density of polyethylene (A), and the amount of MFR and vinyl acetate of ethylene-vinyl acetate copolymer (B) can be increased or decreased. Further, for example, polyethylene (A) can be increased or decreased. ) And the ethylene-vinyl acetate copolymer (B) can be adjusted by adjusting the blending ratio.

4-5. Characteristics (V) Melting Point Peak The polyethylene resin composition for a telescopic rod net of the present invention has a melting point peak of at least 106 ° C. or lower. No particular lower limit is set, but it is usually 70 ° C. or higher. When the melting point peak is 106 ° C. or lower, the extruded strands can be satisfactorily adhered to each other.
The melting point peak is raised from 30 ° C. to 190 ° C. at a heating rate of 100 ° C./min by using a differential scanning calorimeter manufactured by PerkinElmer Co., Ltd., trade name "DSC8500", according to JIS K7121 (2010). Extrapolated peak from the thermogram measured when warmed, held at 190 ° C. for 5 minutes, cooled to 30 ° C. at a cooling rate of 10 ° C./min, and then raised to 200 ° C. at a heating rate of 10 ° C./min. The end point (° C) can be calculated and obtained as the melting point peak.

5. Method for manufacturing polyethylene resin composition for telescopic rod net 5-1. Production of Polyethylene (A) The type of polyethylene-based resin of polyethylene (A) used in the present invention is preferably an ethylene-based polymer, and is a homopolymer of ethylene and / or a combination of ethylene and α-olefin. It is preferably a polymer.
Polyethylene (A) can be copolymerized with ethylene or an α-olefin having 3 to 12 carbon atoms of ethylene, for example, propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene. It is obtained by copolymerization with etc. In addition, copolymerization with diene is also possible depending on the purpose. Examples of the diene compound used at this time include butadiene, 1,4-hexadiene, ethylidene norbornene, dicyclopentadiene and the like. The comonomer content in the polymerization of polyethylene (A) can be arbitrarily selected. For example, in the case of copolymerization of ethylene and α-olefin having 3 to 12 carbon atoms, ethylene / α The α-olefin content in the −olefin copolymer is 0 to 40 mol%, preferably 0 to 30 mol%.
The polyethylene (A) according to the present invention is preferably an ethylene-based polymer polymerized using a catalyst for olefin polymerization.
The raw material monomer, polymerization method, etc. of the ethylene-based polymer of polyethylene (A) according to the present invention are the same as those of the ethylene-based polymer of polyethylene (A) described above.

The ethylene-based polymer of polyethylene (A) in the present invention is carried out by a method of homopolymerizing ethylene or copolymerizing with the above-mentioned α-olefin using a catalyst for olefin polymerization.
Various types of catalysts for olefin polymerization are known today, and there are no restrictions as long as the above-mentioned ethylene-based polymer can be prepared within the range of the composition of the catalyst component and the device of polymerization conditions and post-treatment conditions. Although not, examples of techniques suitable for producing the above ethylene-based polymer and satisfying economic efficiency at the industrial level include (I) metallocene catalysts and (II) post-metallocene catalysts, among which (I) A metallocene catalyst is preferable, and a long-chain branched metallocene catalyst is more preferable.

(I) Metallocene catalyst As an example of a polymerization catalyst suitable for producing an ethylene-based polymer of polyethylene (A), a metallocene catalyst (for example, "with a metallocene catalyst" which is an olefin polymerization catalyst composed of a metallocene-based transition metal compound and a co-catalyst component Next-generation polymer industrialization technology (first and second volumes); published by Interresearch Co., Ltd. in 1994, etc.) is relatively inexpensive, highly active, excellent in polymerization process suitability, and has a molecular weight distribution and a copolymerization composition distribution. It is used because a narrow ethylene-based polymer can be obtained.
Details of those suitably used for producing an ethylene-based polymer of polyethylene (A) will be described later.

(II) Post-metallocene catalyst As an example of a polymerization catalyst suitable for producing an ethylene-based polymer of polyethylene (A), an olefin polymerization catalyst using a homogeneous metal complex (non-metallocene complex) other than the above-mentioned metallocene-based transition metal compound. Post-metallocene catalysts (for example, "Polyethylene Technology Reader; 2001 Industrial Research Association Co., Ltd.", "Living Polymerization by Uniform Transition Metal Catalyst; 1999 IPC Co., Ltd.", "Catalyst Utilization Dictionary;" (Issued by the 2004 Industrial Research Council, etc.)), but it is used because it is relatively inexpensive, has excellent activity, and an ethylene-based polymer having a narrow molecular weight distribution and copolymerization composition distribution can be obtained.

Among them, Japanese Patent Publication No. 10-513489, Japanese Patent Publication No. 2002-521538, Japanese Patent Publication No. 2000-516295, Japanese Patent Table 2000-514132, Periodic Tables, 1996, p5241, JACS, 1997, 119, p3830, JACS , 1999, 121, p5798, Organometallics, 1998, p3155, etc., a ligand having at least two N atoms binds to a transition metal of Group 3 to 11 of the periodic table through the two N atoms. A bisimide compound, an iminoamide compound, and a bisamide compound of a transition metal having a 4- to 8-membered ring chelate structure containing the transition metal thus formed are preferably used.

Further, a ligand having at least two O atoms or S atoms disclosed in JP-A-6-136048 or the like passes through the two O atoms or S atoms and is a transition metal of Group 3 to 11 of the periodic table. Bishydrocarbyloxy compounds and bishydrocarbylthio compounds of transition metals having a 4- to 8-membered ring chelate structure containing the transition metal formed by binding to, and JP-A-2000-514132, JP-A-2003-535107. A ligand having at least one N atom, S atom or P atom and a carboxyl group (COO) disclosed in Japanese Patent Application Laid-Open No. 2007-77395, etc. is the N atom, S atom or P atom and carboxyl. Iminocarboxylate compound, thiocarboxylate compound, phosphine carboxylate of transition metal having a 4- to 8-membered ring chelate structure containing the transition metal formed by binding to the transition metal of groups 3 to 11 of the periodic table through a group. Examples include those in which the compound is preferably used.

Further, a ligand having at least one P atom or N atom and a carbonyl group (CO) disclosed in Japanese Patent Publication No. 2004-517933, etc. passes through the P atom or N atom and a carbonyl group, and the periodic table No. 3 Β-keto-phosphine compound, β-keto-imide compound, β-keto-amide of a transition metal having a 4- to 8-membered ring chelate structure containing the transition metal formed by binding to the transition metal of groups -11. The compound and the ligand having at least one P atom or N atom and O atom disclosed in JP-A-64-14217, JP-A-2004-517933, etc. are the P atom or N atom. A transition metal γ-oxy-phosphine compound, γ-oxy-imide, having a 4- to 8-membered ring chelate structure containing the transition metal formed by binding to a transition metal of groups 3 to 11 of the periodic table through an O atom. Compounds, γ-oxy-amide compounds, JP-A-6-184214, JP-A-10-195090, JP-A-2002-521534, JP-A-2007-46032, JP-A-2007-7395, etc. By binding a ligand having at least one P atom and a sulfonic acid residue (SO ₃ ) to a transition metal of Group 3 to 11 of the periodic table through the P atom and the sulfonic acid residue. In the transition metal γ-sulfonato-phosphine compound having a 4- to 8-membered ring chelate structure containing the transition metal to be formed, JP-A-11-315109, Chemical Communications (2003), (18), 2272-2273, etc. The disclosed ligand having at least N atom and phenoxy group is formed by binding to the transition metal of Group 3 to 11 of the periodic table through the O atom of the N atom and the phenoxy group. Phenoxyimine compounds and phenoxyamine compounds of transition metals having a ~ 8-membered ring chelate structure are preferably used.

As these non-metallocene complex catalysts, those having a central metal of Group 4B of the periodic table, Ti, Zr, Hf, V, Cr, Fe, Co, Ni, and Pd, are more preferably used because they exhibit high activity. Metals of Ti, Zr, Hf, Fe, Ni, and Pd are more preferably used. However, some of these post-metallocene catalysts tend to contain a long-chain branched structure in the produced ethylene-based polymer, a short-chain branched structure centered on a methyl branch, and a widening molecular weight distribution. When used as the polyethylene (A) used in the present invention, it is necessary to pay particular attention to satisfying the above-mentioned properties (a1) to (a4).

Regarding the production of the ethylene-based polymer of polyethylene (A) used in the present invention, when polymerizing or copolymerizing ethylene, a liquid such as slurry polymerization, solution polymerization, bulk polymerization in a liquid monomer, or suspension polymerization Any method such as a phase polymerization method or a vapor phase polymerization method can be adopted. In the case of the slurry polymerization method, either a slurry polymerization method using a pipe loop type reactor or a slurry polymerization method using an autoclave type reactor can be used. The industrial polymerization process is described in detail in "Polyethylene Technology Reader", edited by Kazuo Matsuura and Naotaka Mikami, p. 148, 2001, Kogyo Chosakai. As the polymerization method, a slurry polymerization method or a gas phase polymerization method is preferable, and a gas phase polymerization method is more preferable.

The liquid phase polymerization method is usually carried out in a hydrocarbon solvent. As the hydrocarbon solvent, a single or a mixture of inert hydrocarbons such as propane, n-butane, isobutane, n-pentane, isopentane, hexane, heptane, octane, decane, cyclohexane, benzene, toluene and xylene or a liquid monomer is used. Be done. As the vapor phase polymerization method, a commonly known polymerization method such as a fluidized bed or a stirring bed can be adopted in the coexistence of an inert gas, and in some cases, a so-called condensin mode in which a medium for removing heat of polymerization coexists can also be adopted. ..

In the catalyst for olefin polymerization containing a transition metal suitable for the production of the ethylene-based polymer of polyethylene (A) in the present invention, which satisfies the economic efficiency at the industrial level, the (I) metallocene catalyst is more suitable than other catalysts. Since an ethylene-based polymer having a narrow molecular weight distribution and copolymerization composition distribution is produced, it is particularly suitable from the viewpoint of improving the mechanical properties and transparency of the polyethylene resin composition and the molded product.

As an example of a catalyst for olefin polymerization that produces a long-chain branched structure suitable as an ethylene-based polymer of polyethylene (A), a recently discovered crosslinked (cyclopentadienyl) (indenyl) ligand or the like is used. A method of using a complex having a compound as an essential catalyst component (invention of Japanese Patent Application No. 2010-268037, etc.), and as another example, a method of using a complex having a benzoindenyl ligand or the like as a catalyst component (Japanese Patent Laid-Open No. 2006). -2098, etc.), and as yet another example, a complex having a crosslinked bis (indenyl) ligand or a crosslinked bis (azulenyl) ligand or a crosslinked bis (cyclopentadienyl) ligand as a metallocene complex. Examples thereof include a method using a catalyst using a mixture of a borane compound or a borate compound, which is a compound that produces an organic aluminum oxy compound and a cationic metallocene compound.

An example of an olefin polymerization catalyst containing a complex having a crosslinked (cyclopentadienyl) (indenyl) ligand or the like that produces a long-chain branched structure suitable as an ethylene-based polymer of polyethylene (A) as an essential component is as follows. Is specifically exemplified as a catalyst for olefin polymerization composed of the catalyst component (a), the catalyst component (b) and the preferable catalyst component (c).
Catalyst component (a): metallocene compound represented by the general formulas (a-1-1) to (a-1-3) Catalyst component (b): a cationic metallocene compound that reacts with the metallocene compound of the catalyst component (a). Compound catalyst component (c): fine particle carrier

(I) Catalyst component (a)
The catalyst component (a) is preferably a metallocene compound represented by the following general formula (a-1-1).

[In formula (a-1-1), M represents any transition metal of Ti, Zr or Hf. Independently, X ¹ and X ² are a hydrogen atom, a halogen, a hydrocarbon group having 1 to 20 carbon atoms, a hydrocarbon group having 1 to 20 carbon atoms including oxygen or nitrogen, and a hydrocarbon having 1 to 20 carbon atoms. A group-substituted amino group or an alkoxy group having 1 to 20 carbon atoms is shown. Q ₁ and _{Q 2} shows a carbon atom, silicon atom or germanium atom. R ¹ each independently represents a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, four R ¹ together with Q ₁ and Q ₂ are bonded may form a ring .. m is 0 or 1, and when m is 0, Q ₁ is directly coupled to a conjugated 5-membered ring containing R ² and R ³ . R ² is a hydrogen atom, a halogen, a hydrocarbon group having 1 to 20 carbon atoms, a silicon-containing hydrocarbon group having 1 to 18 carbon atoms including silicon numbers 1 to 6, a halogen-containing hydrocarbon group having 1 to 20 carbon atoms, and the like. It shows a hydrocarbon group having 1 to 20 carbon atoms containing oxygen or a hydrocarbon group substituted silyl group having 1 to 20 carbon atoms, but even if a plurality of R ^2s are hydrocarbon groups or the like, they are bonded as shown in R ⁴ below. It does not form a ring with the carbon atom. R ³ represents a saturated or unsaturated divalent hydrocarbon group having 4 or 5 carbon atoms that forms a condensed ring with respect to the 5-membered ring to be bonded. R ⁴ is an atom or group that bonds to the carbon atom of R ³ , and independently has a hydrogen atom, a halogen, a hydrocarbon group having 1 to 20 carbon atoms, and 1 to 18 carbon atoms including 1 to 6 carbon atoms. The silicon-containing hydrocarbon group, the halogenated hydrocarbon group having 1 to 20 carbon atoms, or the hydrocarbon group substituted silyl group having 1 to 20 carbon atoms is shown. n represents an integer from 0 to 10, and when n is 2 or more, R ⁴ may form a ring together with the bonded carbon atom. R ⁵ is a hydrogen atom, a halogen, a hydrocarbon group, a silicon-containing hydrocarbon group having 1 to 18 carbon atoms containing silicon atoms from 1 to 6, a halogen-containing hydrocarbon group having 1 to 20 carbon atoms having 1 to 20 carbon atoms, It shows a hydrocarbon group having 1 to 20 carbon atoms containing oxygen or a hydrocarbon group substituted silyl group having 1 to 20 carbon atoms, but even if a plurality of R ^5s are hydrocarbon groups or the like, they are bonded like R ^4. It does not form a ring with a carbon atom.

The metallocene compound of the catalyst component (a) is preferably represented by the following general formula (a-1-2).

The metallocene compound of the catalyst component (a) is more preferably represented by the following general formula (a-1-3).

Particularly preferable metallocene compounds as the catalyst component (a) are shown below.
Dimethylsilylene (cyclopentadienyl) (indenyl) zirconium dichloride, isopropylidene (cyclopentadienyl) (indenyl) zirconium dichloride, dimethylsilylene (cyclopentadienyl) (3-methylindenyl) zirconium dichloride, dimethylsilylene (cyclo) Pentazienyl) (3-phenylindenyl) zirconium dichloride, dimethylsilylene (cyclopentadienyl) (4-phenylindenyl) zirconium dichloride, dimethylsilylene (cyclopentadienyl) (benzo [e] indenyl) zirconium dichloride, Isopropylidene (cyclopentadienyl) (3-methylindenyl) zirconium dichloride, dimethylsilylene (cyclopentadienyl) (3-t-butylindenyl) zirconium dichloride, isopropylidene (cyclopentadienyl) (3-t -Butylindenyl) zirconium dichloride, dimethylgelmilene (cyclopentadienyl) (indenyl) zirconium dichloride, cyclobutylidene (cyclopentadienyl) (3-t-butylindenyl) zirconium dichloride, dimethylsilylene (cyclopentadi Zirconium (indenyl) hafnium dichloride, dimethylsilylene (cyclopentadienyl) (3-methylindenyl) hafnium dichloride, dimethylsilylene (cyclopentadienyl) (3-t-butylindenyl) hafnium dichloride, dimethylsilylene (4) -T-butylcyclopentadienyl) (indenyl) zirconium dichloride, dimethylsilylene (4-t-butylcyclopentadienyl) (indenyl) zirconium dichloride, dimethylsilylene (4-t-butylcyclopentadienyl) (indenyl) Examples include zirconium dimethyl.

(II) Catalyst component (b)
Olefin polymerization exemplified as a catalyst for olefin polymerization containing a complex having a crosslinked (cyclopentadienyl) (indenyl) ligand or the like that produces a long-chain branched structure suitable as an ethylene-based polymer of polyethylene (A) as an essential component. In addition to the catalyst component (a), the catalyst for use contains a compound (catalyst component (b)) that reacts with the metallocene compound of the catalyst component (a) to form a cationic metallocene compound.

(III) Catalyst component (c)
Olefin polymerization exemplified as a catalyst for olefin polymerization containing a complex having a crosslinked (cyclopentadienyl) (indenyl) ligand or the like that produces a long-chain branched structure suitable as an ethylene-based polymer of polyethylene (A) as an essential component. The catalyst for use contains the catalyst component (b) in addition to the catalyst component (a), and preferably contains the catalyst component (c).

Examples of the fine particle carrier as the catalyst component (c) include an inorganic carrier, a particulate polymer carrier, or a mixture thereof. As the inorganic carrier, a metal, a metal oxide, a metal chloride, a metal carbonate, a carbonaceous substance, or a mixture thereof can be used.
Suitable metals that can be used for the inorganic carrier include, for example, iron, aluminum, nickel and the like.

5-2. Production of Ethylene-Vinyl Acetate Copolymer (B) As a method for producing the ethylene-vinyl acetate copolymer (B), any method is used as long as the ethylene-vinyl acetate copolymer (B) of the present invention can be obtained. For example, a method of blending ethylene-vinyl acetate copolymers (B) having different molecular weights and vinyl acetate unit contents, and copolymerizing ethylene and vinyl acetate using a radical initiator under high pressure and high temperature conditions. Examples thereof include a method using high-pressure radical polymerization. In the high-pressure radical polymerization method, the polymerization temperature and polymerization pressure are not only the growth rate, the stop rate or the chain transfer rate, but also the reactivity ratio between ethylene and vinyl acetate. affect. Therefore, the ethylene-vinyl acetate copolymer (B) having a composition distribution can be produced by changing the reactivity ratio by imparting a temperature distribution or a pressure distribution in the reactor. Further, when the monomer gas can be injected into the reactor at multiple points, it can be produced by changing the feed monomer gas composition.

5-3. Mixing of polyethylene (A) and ethylene-vinyl acetate copolymer (B) The polyethylene resin composition for a telescopic rod net of the present invention is obtained by mixing polyethylene (A) and ethylene-vinyl acetate copolymer (B). It can be produced by mixing polyethylene (A) and ethylene-vinyl acetate copolymer (B), which are separately produced, by a known method.

The ethylene resin composition for a telescopic rod net of the present invention can be pelletized by mechanical melt mixing with a pelletizer, a homogenizer, or the like according to a conventional method, and then molded by various molding machines to obtain a desired molded product. ..
Further, the ethylene resin composition for the telescopic rod net obtained by the above method includes other olefin-based polymers, rubber, etc., as well as antioxidants, ultraviolet absorbers, light stabilizers, lubricants, and charges according to a conventional method. Known additives such as inhibitor, antifogging agent, antiblocking agent, processing aid, coloring pigment, cross-linking agent, foaming agent, inorganic or organic filler, flame retardant and the like can be blended.
As the additive, for example, one or more kinds of antioxidants (phenolic, phosphorus, sulfur), lubricants, antistatic agents, light stabilizers, ultraviolet absorbers and the like can be appropriately used in combination. As the filler, calcium carbonate, talc, metal powder (aluminum, copper, iron, lead, etc.), diatomaceous earth, diatomaceous earth, alumina, gypsum, mica, clay, asbestos, graphite, carbon black, titanium oxide, etc. can be used. Of these, calcium carbonate, talc, mica and the like are preferably used. In any case, the polyethylene resin composition can be mixed with various additives as necessary and kneaded with a kneading extruder, a Banbury mixer or the like to be used as a molding material.

6. Molding and Use of Polyethylene Resin Composition for Telescopic Rod Net The polyethylene resin composition for telescopic rod net can use a conventionally known molding method.
Examples of the molded product include a telescopic rod net represented by a "mandarin orange net" and a "fruit net".

In the following, the present invention will be described in more detail with reference to Examples and Comparative Examples to demonstrate the excellence of the present invention and the superiority in the configuration of the present invention, but the present invention is limited by these examples. It's not a thing.

[Measurement method of physical properties]
(1) MFR
The measurement was carried out at 190 ° C. and a load of 2.16 kg in accordance with JIS K7210 "Test method for melt mass flow rate (MFR) and melt volume flow rate (MVR) of plastic-thermoplastic plastic".

(2) Density Polyethylene pellets were hot-pressed to prepare a press sheet having a thickness of 2 mm, and the sheet was placed in a beaker having a capacity of 1000 ml, filled with distilled water, covered with a watch glass, and heated with a mantle heater. After boiling the distilled water for 60 minutes, the beaker was placed on a wooden table and allowed to cool. At this time, the boiling distilled water after boiling for 60 minutes was set to 500 ml, and the time until the room temperature was adjusted so as not to be 60 minutes or less. In addition, the test sheet was immersed in a substantially central portion of water so as not to come into contact with the beaker and the water surface. After annealing the sheet under the conditions of 23 ° C. and 50% humidity within 16 hours or more and 24 hours or less, the sheet is punched to a length and width of 2 mm, and at a test temperature of 23 ° C., JIS K7112 "Plastic-non-foamed plastic density" And the measurement method of specific gravity ”.

(3) Branch index (g _C )
The branching index (g') was calculated as a ratio (ηbranch / ηlin) between the ultimate viscosity (ηbranch) obtained by measuring a sample with a Viscometer and the ultimate viscosity (ηlin) obtained by separately measuring a linear polymer. ..

(4) W ₂ + W ₃
It was determined from the integrated elution curve measured by cross fractional chromatography (CFC).
The cross fractionation chromatograph (CFC) used was composed of a temperature-increasing elution fractionation (TREF) section for crystalline fractionation and a gel permeation chromatography (GPC) section for molecular weight fractionation.

(5) Vinyl Acetate Content Measured in accordance with JIS K7192 "Plastic-Ethylene Vinyl Acetate Resin (EVAC) -Vinyl Acetate Content Measuring Method".

(6) Flexural modulus at 23 ° C. A test piece having a thickness of 10 mm × 80 × 4 mmt was cut out from a 4 mm thick molded sheet prepared by compression molding according to JIS K6922-2 and measured with JIS K7171.

(7) Melt tension at 190 ° C. Using Capillograph 1B manufactured by Toyo Seiki Seisakusho Co., Ltd., the molten resin is extruded and wound under the conditions of temperature 190 ° C., orifice diameter 2.095 mm, orifice length 8.0 mm, and extrusion speed 15 mm / min. The load when wound at a speed of 3.8 m / min was measured by the machine (unit: mN).

(8) Tensile Impact Strength at 23 ° C. A test piece of 10 mm × 80 × 4 mmt was cut out from a 4 mm thick molded sheet prepared by compression molding according to JIS K6922-2, and measured by ISO 8256.

(9) Melting point peak temperature measured by a differential scanning calorimeter (DSC) Using a differential scanning calorimeter manufactured by PerkinElmer, trade name "DSC8500", heat about 5 mg of a sample according to JIS K7121 (2010). The temperature is raised from 30 ° C. to 190 ° C. at a rate of 100 ° C./min, held at 190 ° C. for 5 minutes, then lowered to 30 ° C. at a cooling rate of 10 ° C./min, and then to 200 ° C. at a heating rate of 10 ° C./min. The end point (° C) of the supplementary peak was calculated from the thermogram measured when the temperature was raised and obtained as the melting point peak.

(10) Contact strength:
The melt tension at 190 ° C. and the melting point peak temperature measured by the differential scanning calorimeter (DSC) satisfying the characteristics (III) and the characteristics (V) at the same time were designated as “◯”, and the others were designated as “x”. When the contact strength was "○", peeling of the fused portion hardly occurred in the stretching step during net forming, but when the contact strength was "x", the fused portion was formed in the stretching step during net forming. Inconvenience such as peeling occurred.

(11) Stretch strength:
Those having a tensile impact strength at 23 ° C. satisfying the characteristic (IV) were designated as "◯", and those other than that satisfying the characteristic (IV) were designated as "x". When the stretching strength was "○", stable stretching was possible in the stretching step during net molding, but when the stretching strength was "x", the stretched portion was cut in the stretching step during net molding. Etc. have occurred.

(12) Product rigidity:
Those having a flexural modulus at 23 ° C. satisfying the characteristic (II) were designated as “◯”, and those other than that satisfying the characteristic (II) were designated as “x”. When the product rigidity was "○", the contents could be handled flexibly without damaging the contents when using the net, but when the product rigidity was "×", inconveniences such as damaging the contents when using the net occurred.

(13) Comprehensive evaluation:
Those satisfying the above contact strength, stretching strength, and product rigidity at the same time were designated as "○", and the others were designated as "x".

[Example 1]
(1) Production of polyethylene (A) <Synthesis of catalyst for olefin polymerization>
Under a nitrogen atmosphere, 30 grams of silica calcined at 600 ° C. for 5 hours was placed in a 500 ml three-necked flask, and dried under reduced pressure with a vacuum pump for 1 hour while heating in an oil bath at 150 ° C. 412 mg of dimethylsilylene (4- (4-trimethylsilyl-phenyl) -indenyl) (cyclopentadienyl) zirconium dichloride was placed in a separately prepared 200 ml two-necked flask under a nitrogen atmosphere and dissolved in 80.7 ml of dehydrated toluene. Further, at room temperature, 83.1 ml of a 20% methylaluminoxane / toluene solution manufactured by Albemar was added and stirred for 30 minutes. While heating and stirring a 500 ml three-necked flask containing vacuum-dried silica in an oil bath at 40 ° C., a total amount of a toluene solution of the reaction product of the zirconosen complex and methylaluminoxane was added. After stirring at 40 ° C. for 1 hour, the toluene solvent was distilled off under reduced pressure while heating at 40 ° C. to obtain a powdery catalyst.
<Manufacturing of ethylene / 1-hexene copolymer>
Using the powdery catalyst obtained in the above <Synthesis of catalyst for olefin polymerization>, hexene / ethylene molar ratio 0.40%, hydrogen / ethylenemol ratio 0.49%, nitrogen concentration 26 mol%, total pressure 0.8 MPa The powdery catalyst was intermittently applied to a gas phase continuous polymerization apparatus (internal volume 100 L, fluid bed diameter 10 cm, fluid bed type polymer (dispersant) 1.8 kg) prepared in the above at a rate of 0.21 g / hour. Polymerization was carried out with the gas composition and temperature kept constant while supplying. Further, in order to maintain the cleanliness in the system, 0.03 mol / L of a hexane-diluted solution of triethylaluminum (TEA) was supplied to the gas circulation line at 15.7 ml / hr. As a result, the average production rate of the produced polyethylene was 345 g / hour. The MFR and density of the ethylene / 1-hexene copolymer obtained after producing a cumulative polyethylene of 5 kg or more were 0.30 g / 10 min and 0.921 g / cm ³ , respectively. The gc was 0.67, and W ₂ + W ₃ was 55% by mass.

(2) Ethylene-vinyl acetate copolymer (B)
Ethylene-vinyl acetate copolymer manufactured by Japan Polyethylene Corporation: Novatec ^TM EVA LV211A (MFR = 0.3 g / 10 minutes, vinyl acetate content = 6% by mass) was used.

(3) Production of Polyethylene Resin Composition for Telescopic Rod Net Polyethylene (A) and ethylene-vinyl acetate copolymer (B) are melt-mixed at the composition ratios shown in Table 2 to obtain a polyethylene resin composition for telescopic rod net. Manufactured. Table 2 shows the physical properties and evaluation results of the resin composition. With the obtained composition, it was possible to produce a molded product having excellent molding processability and excellent texture.

[Examples 2 to 9]
According to Example 1, polyethylene (A) and ethylene-vinyl acetate copolymer (B) in Table 2 were used and melt-mixed at the composition ratios shown in Table 2 to produce a polyethylene resin composition for a telescopic rod net. did. Table 2 shows the physical properties and evaluation results of the resin composition. With the obtained composition, it was possible to produce a molded product having excellent molding processability and excellent texture.

[Comparative Example 1]
Table 2 shows the physical properties and evaluation results of Linear Low Density Polyethylene: Novatec ^TM LL UF230 manufactured by Japan Polyethylene Corporation, which has an MFR of 1 g / 10 minutes and a density of 0.921 g / cm ³ . The resin of Comparative Example 1 was inferior in moldability, contact strength, draw strength, and product rigidity.

[Comparative Example 2]
Table 2 shows the physical properties and evaluation results of the ethylene polymer (LCB-LLDPE) having an MFR of 0.13 g / 10 min and a density of 0.919 g / cm ³ produced according to Example 1. The obtained resin was inferior in moldability, contact strength, and product rigidity.

[Comparative Example 3]
Table 2 shows the physical properties and evaluation results of ethylene-vinyl acetate copolymer manufactured by Japan Polyethylene Corporation having an MFR of 0.3 g / 10 min: Novatec ^TM EVA LV211A. The resin of Comparative Example 3 had a low tensile impact strength and was inferior in stretching strength.

[Comparative Example 4]
An ethylene-based polymer (LCB-LLDPE) having an MFR of 0.13 g / 10 min and a density of 0.919 g / cm ^{3 and} an ethylene-vinyl acetate copolymer manufactured by Japan Polyethylene Corporation: Novatec ^TM EVALV430 produced according to Example 1 It was used and melt-mixed at the composition ratios shown in Table 2 to produce a polyethylene resin composition for a telescopic rod net. Table 2 shows the physical properties and evaluation results of the resin composition. The obtained composition had a low flexural modulus and was inferior in product rigidity.

[Evaluation]
As described above, when Examples 1 to 9 and Comparative Examples 1 to 4 are compared from the results shown in Table 2, the polyethylene resin composition and the molded product thereof according to the present invention are molded as shown in Examples 1 to 9. It was confirmed that the balance between workability and product rigidity was good. Further, the polyethylene resin composition and the molded product thereof, which do not satisfy the specific requirements of the present invention, were inferior in the balance between molding processability and product rigidity to the polyethylene resin compositions of Examples 1 to 9 (Comparative Example 1). ~ 4).

The polyethylene resin composition for a telescopic rod net of the present invention is excellent in molding processability and flexibility, and can provide a material particularly useful as a material for a telescopic rod net, and particularly constitutes a net. Since it is possible to provide a polyethylene resin composition for a telescopic rod net which is excellent in adhesive strength between material strands, has less peeling of a fused portion in a stretching step during net molding, and enables stable production, and a molded product made of the same. Extremely useful industrially.

Claims (2)

Ethylene-α-olefin copolymer having the following properties (a1) to (a4) in an amount of 10 to 30% by mass, and ethylene-vinyl acetate copolymer (B) 70 to 90 having the following properties (b1) to (b2). A polyethylene resin composition for a telescopic rod net containing% by mass and having the following characteristics (I) to (V).
Characteristic (a1): The melt flow rate (MFR) measured at a temperature of 190 ° C. and a load of 2.16 kg is 0.1 to 1.5 g / 10 minutes.
Characteristic (a2): The density is 0.9000 to 0.930 g / cm ³ .
Characteristic (a3): Molecular weight of branch index (g') measured by a gel permeation chromatography (GPC) measuring device equipped with a differential refractometer, a viscosity detector and a light scattering detector as detectors, with a molecular weight of 100,000 to 1,000,000. The lowest value (gc) between them is 0.40 to 0.85.
Property (a4): Percentage of components whose molecular weight is equal to or greater than the weight average molecular weight among the components eluted at a temperature or lower at which the elution amount determined from the integrated elution curve measured by cross fractionation chromatography (CFC) is 50% by mass (W). ₂ ) and the sum of the proportions (W ₃ ) of the components whose molecular weight is less than the weight average molecular weight among the components eluted at a temperature higher than the temperature at which the elution amount obtained from the integrated elution curve is 50% by mass (W ₂ + W ₃ ). However, it is 40 to 80% by mass.
Characteristic (b1): MFR is 0.1 to 1.5 g / 10 minutes.
Property (b2): The vinyl acetate content is 5 to 20% by mass.
Characteristic (I): MFR is 0.1 to 1.5 g / 10 minutes.
Characteristic (II): The flexural modulus at 23 ° C. is 80 to 250 MPa.
Characteristic (III): The melting tension at 190 ° C. is 75 mN or more.
Characteristic (IV): The tensile impact strength at 23 ° C. is 300 KJ / m ² or more.
Characteristic (V): One of the melting point peaks measured by a differential scanning calorimeter (DSC) is 106 ° C. or lower. A molded product composed of the polyethylene resin composition for a telescopic rod net according to claim 1.