JP2022156609A - polyethylene for film - Google Patents

Abstract

To provide polyethylene which has an improved property to be thinned and has improved handleability.SOLUTION: There is provided, polyethylene which, in an integrated distribution curve of polyethylene evaluated by gel permeation chromatography, has a ratio of a weight fraction (WLog10M>5.25: unit in wt%) of a component whose Log10M exceeds 5.25 to a light scattering area (RLS) represented by a following formula 1, (WLog10M>5.25/RLS) of 5.7 to 6.7, in which M is a polyethylene conversion molecular weight: RLS=LS/LS' (formula 1) (in the formula, LS represents a light scattering area of a solution obtained by dissolving 40 mg of the polyethylene in 20 mL of o-dichlorobenzene; and LS' represents a light scattering area of a solution obtained by dissolving 40 mg of standard polyethylene having a number average molecular weight of 1000 in 20 mL of o-dichlorobenzene.)SELECTED DRAWING: None

Description

The present invention relates to polyethylene for films.

Polyethylene is processed and used as a wide variety of films such as heavy bags, shrink wraps, general packaging, thin films, protective films, extrusion laminate films, extrusion films, and foamed films. Among them, especially low-density polyethylene (LDPE) produced by high-pressure radical polymerization is processed and used as extrusion laminate films and protective films (protective films). A protective film is laminated (attached) to an optical material or a metal plate to protect the optical material or the metal plate. For example, it is used as a protective film for protecting a film-like etching resist (dry film resist: DFR) used for circuit formation on a substrate. In producing such a film, a good balance between thinning of the polyethylene and ease of handling is required.

Patent Document 1 describes a DFR protection film made of polyethylene obtained by high-pressure radical polymerization, and a DFR protection film made of a polyethylene film in which the density of fisheyes present in the film is within a specific range. ing.

JP-A-2002-60426

Under such circumstances, the problem to be solved by the present invention is to provide a polyethylene which is further improved in its thinness and ease of handling.

In view of such a background, the present inventors have conducted extensive studies and have completed the present invention.
That is, the present invention is as follows.
[1]
In the integral distribution curve of polyethylene evaluated by gel permeation chromatography, the weight fraction of components with Log ₁₀ M exceeding 5.25 (W _Log10M>5.25 : unit is wt%) and (M is polyethylene conversion molecular weight),
A polyethylene having a ratio (W _Log10M>5.25 /R _LS ) to a light scattering area ratio (R _LS ) represented by the following (Formula 1) of 5.7 or more and 6.7 or less.
R _LS =LS/LS' (equation 1)
(In the formula, LS indicates the light scattering area of a solution obtained by dissolving 40 mg of the polyethylene in 20 mL of ortho-dichlorobenzene.
LS' indicates the light scattering area of a solution in which 40 mg of standard polystyrene having a number average molecular weight of 1000 is dissolved in 20 mL of ortho-dichlorobenzene. )

[2] to [4] below are preferred aspects or embodiments of the present invention.
[2]
The polyethylene according to [1], wherein W _Log10M>5.25 /R _LS is 5.8 or more and 6.6 or less.
[3]
The polyethylene according to any one of [1] or [2], wherein the polyethylene is high-pressure low-density polyethylene.
[4]
The polyethylene according to any one of [1] to [3], wherein the polyethylene has a melt flow rate (MFR) of 2 to 6 g/10 minutes.

ADVANTAGE OF THE INVENTION According to this invention, the polyethylene which thinned and the ease of handling was further improved can be provided. The feature of the present invention is that the ratio of the middle to high molecular weight component amount and the ultra high molecular weight component amount of polyethylene is related to the balance between stretchability and haze. Another object of the present invention is to provide a polyethylene having further improved ease of handling. Thinning can be evaluated as stretchability of polyethylene, and ease of handling can be evaluated as unevenness of the film surface, for example, film haze. In the method and apparatus for producing polyethylene of the present invention, the pressure inside the reactor and the temperature difference in the reaction zone inside the reactor can be appropriately controlled.

FIG. 1 shows a schematic process diagram of one embodiment of the polyethylene production flow of the present invention. FIG. 2 shows a schematic process diagram of one embodiment of the polyethylene production flow of the present invention. FIG. 3 shows a schematic process diagram of one embodiment of the polyethylene production flow of the present invention. FIG. 4 shows the relationship between haze and melt drawability (minimum thickness) of the polyethylene films produced in Examples and Comparative Examples of the present invention. FIG. 5 shows a GPC chromatogram (GPC integral distribution curve) for calculating the weight fraction of high-molecular-weight components of the polyethylene produced in Example 1 and Comparative Example 1. FIG. 6 shows LS (Light Scattering Detector) chromatograms for measuring the light scattering area of polyethylene produced in Example 1 and Comparative Example 1. FIG.

<Polyethylene>
Polyethylenes of the present invention are:
In the integral distribution curve of polyethylene evaluated by gel permeation chromatography, the weight fraction of components with Log ₁₀ M exceeding 5.25 (W _Log10M>5.25 : unit is wt%) and (M is polyethylene conversion molecular weight),
A polyethylene having a ratio (W _Log10M>5.25 /R _LS ) to a light scattering area ratio (R _LS ) represented by the following (Formula 1) of 5.7 or more and 6.7 or less.
R _LS =LS/LS' (equation 1)
(In the formula, LS indicates the light scattering area of a solution obtained by dissolving 40 mg of the polyethylene in 20 mL of ortho-dichlorobenzene.
LS' indicates the light scattering area of a solution in which 40 mg of standard polystyrene having a number average molecular weight of 1000 is dissolved in 20 mL of ortho-dichlorobenzene. )
In a preferred aspect or embodiment of the present invention, W _Log10M>5.25 /R _LS is 5.8 or more and 6.6 or less.
The weight fraction of components with Log ₁₀ M exceeding 5.25 (W _{Log 10M>5.25} : unit is % by weight) and the light scattering area ratio (R _LS ) of the polyethylene of the present invention were measured according to the method described below. .

The polyethylene of the present invention can be various polyethylenes such as low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, and high-density polyethylene. Low-density polyethylene is preferred, and high-pressure low-density polyethylene is more preferred. .

The melt flow rate (MFR, unit: g / 10 minutes) of the polyethylene of the present invention is not particularly limited, but in the method specified in JIS K7210-1995, under the conditions of a load of 21.18 N and a temperature of 190 ° C., Method A The melt flow rate measured by is preferably 0.3 to 30 (g/10 minutes), more preferably 1 to 10, and even more preferably 2 to 6. If the MFR is low, thinning may become difficult, and if the MFR is high, stable film formation may become difficult.

The density (unit: kg/m ³ ) of the polyethylene of the present invention is not particularly limited, but is preferably 910-930 kg/m ³ , more preferably 918-930 kg/m ³ , still more preferably 920-928 kg/m ³ . If the density is less than 910 kg/m ³ , the rigidity of the film may be lowered and the workability may become too poor. If it exceeds 930 kg/m ³ , the flexibility of the film may decrease, and when used as a protective film, problems may arise in the adhesion of the film.

Applications of the polyethylene of the present invention include a wide variety of films such as heavy duty bags, shrink wraps, general packaging, thin films, protective films (protective films), extrusion laminate films, extrusion films, and foamed films. Among these, preferred uses are extrusion laminate films and protective films, and particularly preferred uses are protective films.

As a film forming method for producing a film (protective film, etc.) from the polyethylene of the present invention, a known film forming method can be employed. For example, when forming a film, it is possible to use any film forming method such as an inflation method (air cooling method, water cooling method) or a T-die method. . There are no particular limitations on the molding temperature and take-up speed in film molding, but generally a molding temperature of 130 to 230° C. and a take-up speed of 5 to 150 m/min are suitable. The thickness of the film is appropriately selected, but the thickness of the film (protective film, etc.) is generally preferably about 5 to 100 μm, more preferably 10 to 60 μm. Even more preferably, the thickness is between 12 and 25 μm. The polyethylene of the present invention is blended with polyolefin-based resins such as linear low-density polyethylene, high-density polyethylene, ethylene-propylene copolymer, and ethylene-butene copolymer within the range where the effect of the present invention is exhibited. You may Additives that are usually used in polyolefins, specifically, antioxidants, antiblocking agents, lubricants, antistatic agents, ultraviolet absorbers, and the like, may be added as necessary. When polyethylene is produced in the presence of a radical polymerization inhibitor in the polymerization reaction system, a certain amount of the radical polymerization inhibitor present in the reaction system remains in the product. If this residual radical polymerization inhibitor also has an antioxidant ability and its concentration is sufficient, the antioxidant may not be added to the product polyethylene.

<Method for producing polyethylene>
The method for producing the polyethylene of the present invention is not particularly limited, for example the following:
A method for producing polyethylene having the following requirements:
- A method for producing polyethylene, comprising polymerizing high-pressure ethylene in the presence of a polymerization initiator using a tank reactor;
- within the tank reactor there is a reaction zone with at least two different temperature regions;
- A polymerization initiator and ethylene are supplied to a temperature zone located upstream of the reaction zone in the tank reactor, and the ethylene is polymerized to produce polyethylene;
- The polyethylene and unreacted ethylene produced in the upstream temperature zone in the tank reactor are flowed to the downstream temperature zone communicating with the upstream zone in the reaction zone in the reactor, Further formation of polyethylene occurs in this downstream temperature region;
The temperature (T1 [°C]) of the temperature region located upstream of the reaction zone in the tank reactor to which the polymerization initiator is supplied, and the temperature (T2 [°C]) of the temperature region located downstream is 2.1° C. or more and 8.4° C. or less.

The pressure of ethylene used in the production method can be, for example, 100-280 MPa, preferably 100-250 MPa. More preferably 156 to 174 MPa. Below the preferred range, the light scattering area and the weight fraction of components with Log ₁₀ M exceeding 5.25 increase, haze increases, and melt drawability decreases. On the other hand, if the content exceeds the preferred range, the light scattering area and the weight fraction of the component having a Log ₁₀ M of more than 5.25 will decrease, the haze will decrease, and the melt drawability will improve.

The polymerization initiator used in the production method is not particularly limited. Noyl peroxide, octanoyl peroxide, decanoyl peroxide, lauroyl peroxide, propionyl peroxide, tert-butylperoxy-2-ethylhexanoate (t-butylperoxy-2-ethylhexanoate), tert-butylperoxyisobutyrate , tert-butyl peroxylaurate, tert-butyl peroxyisopropyl carbonate, tert-butyl peroxyacetate, tert-butyl peroxybenzoate, dicumyl peroxide, tert-butyl hydroperoxide, and tert-butyl peroxide.

The reactor used in the production method is a tank reactor. The number of reactors used is not particularly limited, and for example, two reactors, three reactors or four or more reactors can be used. When two reactors are used, the two reactors may also be referred to as the front reactor and the rear reactor, respectively.

There can be reaction zones with at least two different temperature regions in the reactor used in the manufacturing process. The reaction zone may have three different temperature zones, four different temperature zones, or five or more different temperature zones. There may be more than one reaction zone in the reactor, such as two reaction zones, three reaction zones or four or more reaction zones. A reaction zone is sometimes referred to as a reaction zone.

A polymerization initiator and ethylene can be supplied to a temperature zone located upstream of the reaction zone in the reactor and the ethylene can be polymerized to produce polyethylene. The polyethylene and unreacted ethylene produced in the upstream temperature region in the reactor are flowed to the downstream temperature region communicating with the upstream region in the reaction zone in the reactor. Polyethylene can be further produced in the temperature range of . When the reactor is a vertical reactor (eg, tank reactor), the upstream and downstream are sometimes referred to as upper and lower, respectively.

The difference between the temperature (T1 [°C]) of the temperature region located upstream of the reaction zone in the reactor to which the polymerization initiator is supplied and the temperature (T2 [°C]) of the temperature region located downstream (ΔT [°C]) can be 2.1°C or higher and 8.4°C or lower. Preferably, ΔT [°C] is 2.2°C or higher and 8.0°C or lower. Preferably, ΔT [° C.]=T2 [° C.]−T1 [° C.]
When ΔT [° C.] is 8.4 or more or 2.1 or less, the weight fraction of the component with Log ₁₀ M exceeding 5.25 increases, and the melt drawability deteriorates.

<Polyethylene manufacturing equipment>
The apparatus for producing the polyethylene of the invention has similar features to the method for producing the polyethylene of the invention described above.

<Specific examples of manufacturing method and manufacturing apparatus>
The reactor, reaction conditions, and the like for the method and apparatus for producing polyethylene of the present invention are not particularly limited, but examples include production methods having the following reactor, reaction conditions, and the like.
Ethylene under high temperature and high pressure is heat-exchanged with a reaction mixture discharged from the preceding tank reactor using a multiple reactor in which two or more tank reactors are connected in series by piping containing a heat exchanger. In the method in which the cooled reaction mixture is again introduced into the latter tank-type reactor for polymerization, most of the raw material ethylene is The remaining raw material ethylene is injected into the upper reaction zone of the latter tank reactor having an upper reaction zone and a lower reaction zone, and the raw material injected into the upper reaction zone of the former tank reactor. Ethylene is polymerized at a pressure of 100 to 280 MPa and a temperature of 130 to 200° C. in the presence of a polymerization initiator, and the reaction mixture thus obtained is led to the lower reaction zone of the preceding tank-type reactor, and the polymerization initiator is added. and the reaction mixture discharged from the end of the preceding tank reactor is placed between the preceding tank reactor and the latter tank reactor. After cooling to a temperature of 120 ° C. or more by a heat exchanger, but 20 ° C. or more lower than the reaction temperature in the lower reaction zone of the preceding tank reactor, it is injected into the latter tank reactor, In the upper reaction zone of the tank reactor, polymerization is performed at a pressure of 100 to 280 MPa and a temperature of 130 to 200 ° C. in the presence of a polymerization initiator, and the reaction mixture thus obtained is transferred to the lower reaction of the latter tank reactor. A method for producing polyethylene, which is introduced into a zone and polymerized at a temperature of 220 to 280° C. in the presence of a polymerization initiator.

In carrying out the method for producing polyethylene, for example, the number of injection points of the raw material ethylene and the polymerization initiator to be injected into the upper reaction zone of the front-stage and/or rear-stage tank-type reactor is adjusted along the length direction of the reactor. It can be two or more. The polymerization initiator may be injected from the same injection point as the raw material ethylene, or may be injected from a different injection point from the raw material ethylene. Various combinations of injection points of the raw material ethylene and the polymerization initiator to be injected into the upper reaction zone can be conceived, but the optimum combination of the injection points can be appropriately determined by those skilled in the art.

Most of the feed ethylene can be injected, for example, into the upper reaction zone of the upstream tank reactor, but the majority of the feed ethylene means 60% or more of the total feed ethylene.

The reaction pressure of ethylene can be, for example, 100-280 MPa, preferably 100-250 MPa. Regarding the reaction pressure, for example, the maximum value of the pressure in the latter tank reactor is the value obtained by subtracting the pressure loss in the pipe leading to the latter tank reactor from the reaction pressure in the former tank reactor. can be arbitrarily adjusted within this range by means of a pressure control valve at the outlet of the preceding tank-type reactor.

The reaction temperature may be, for example, 130 to 250° C., preferably 140 to 250° C. in the upper reaction zone of the former and latter tank reactors, and may be, for example, 200 to 280° C., preferably 200° C. in the lower reaction zone. It can be ~270°C. For example, the reaction temperature in the upper reaction zone may differ between the preceding and subsequent tank reactors. The same is true for the lower reaction zone.

For example, the polymerization initiator used in the upper reaction zone of the front-stage and rear-stage tank reactors is preferably a polymerization initiator having a decomposition temperature of 40 to 80 ° C. for obtaining a half-life of 10 hours, specifically is diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, tert-butyl peroxybivalate, 3,5,5-trimethylhexanoyl peroxide, octanoyl peroxide, decanoyl peroxide, lauroyl peroxide, propionyl peroxide, tributylperoxy-2-ethylhexanoate (t-butylperoxy-2-ethylhexanoate), tert-butylperoxyisobutyrate and the like.
For example, the amount of the polymerization initiator used for the polymerization of ethylene in the upper reaction zone of the former stage and the latter stage may be 50 to 1000 parts by weight per 1000000 parts by weight of ethylene.
For example, the polymerization initiator used in the lower reaction zone of the front-stage and rear-stage tank reactors is preferably a polymerization initiator having a decomposition temperature of 70 to 140 ° C. for obtaining a half-life of 10 hours, specifically is tert-butyl peroxy-2-ethylhexanoate (t-butyl peroxy-2-ethylhexanoate), tert-butyl peroxyinbutyrate, tert-butyl peroxylaurate, tert-butyl peroxyisopropyl carbonate, tert-butyl peroxyacetate, tert-butyl peroxybenzoate, dicumyl peroxide, tert-butyl hydroperoxide, tert-butyl peroxide and the like.
For example, in the former and latter lower reaction zones, the amount of the polymerization initiator used for ethylene polymerization may be 5 to 500 parts by weight per 1,000,000 parts by weight of ethylene.
For example, the polymerization initiator can be used singly or in a mixture of two or more in the one-part reaction zone or the lower reaction zone of the first and second tank reactors.

The raw ethylene gas may contain, for example, 0.1 to 10 mol % of a chain transfer agent with respect to ethylene.
Examples of chain transfer agents include paraffins such as ethane, propane, butane, pentane, hexane and heptane; , aldehydes such as propionaldehyde, ketones such as acetone, methyl ethyl ketone, diethyl ketone and cyclohexanone, and aromatic hydrocarbons such as benzene, toluene, and xylene.

<Specific example in implementation (production of polyethylene) in FIGS. 1, 2 and 3>
In the implementation in FIG. 1 (Examples 1 to 3), the implementation in FIG. 2 (Examples 4 and 5) and the implementation in FIG. 3, for example, the following conditions can be adopted.
In the implementation in Figure 1:
The discharge pressure of the secondary compressor (pipe 9) can be, for example, 100-300 MPa, preferably 150-250 MPa;
The total raw material ethylene supply amount (gas rate of raw material ethylene) (pipe 9) can be, for example, 5 to 30 tons/hour, preferably 10 to 20 tons/hour;
The raw material ethylene supply amount (pipe 10) at the upper part of the tank reactor 20 can be, for example, 1 to 15 tons/hour, preferably 3 to 10 tons/hour;
The raw material ethylene supply amount (pipe 11) at the bottom of the tank reactor 20 can be, for example, 1 to 20 tons/hour, preferably 5 to 10 tons/hour;
The raw material ethylene supply amount (pipe 12) at the upper part of the tank reactor 21 can be, for example, 1 to 15 tons/hour, preferably 3 to 10 tons/hour;
The polymerization initiator supply rate (pipe 13) at the top of the tank reactor 20 can be, for example, 1 to 10 kg/hour, preferably 2 to 8 kg/hour;
The polymerization initiator supply rate (pipe 14) at the bottom of the tank reactor 20 can be, for example, 1 to 10 kg/hour, preferably 2 to 8 kg/hour;
The polymerization initiator supply rate (pipe 15) at the top of the tank reactor 21 can be, for example, 1 to 10 kg/hour, preferably 1 to 8 kg/hour;
The polymerization initiator supply rate (pipe 16) at the bottom of the tank reactor 21 can be, for example, 0 to 10 kg/hour, preferably 0 to 8 kg/hour.

In the implementation in Figure 2:
The discharge pressure of the secondary compressor (pipe 5) can be, for example, 100-300 MPa, preferably 150-250 MPa;
The total raw material ethylene supply amount (gas rate of raw material ethylene) (pipe 5) can be, for example, 5 to 30 tons/hour, preferably 10 to 20 tons/hour;
The raw material ethylene supply amount (pipe 6) at the upper part of the tank reactor 11 can be, for example, 1 to 15 tons/hour, preferably 3 to 10 tons/hour;
The raw material ethylene supply amount (pipe 7) at the bottom of the tank reactor 11 can be, for example, 1 to 20 tons/hour, preferably 5 to 10 tons/hour;
The amount of polymerization initiator supplied to the upper part of the tank reactor 11 (pipe 8) can be, for example, 1 to 10 kg/hour, preferably 2 to 8 kg/hour;
The polymerization initiator supply rate (pipe 9) at the bottom of the tank reactor 11 can be, for example, 1 to 10 kg/hour, preferably 1 to 8 kg/hour.

In the implementation in Figure 3:
The total amount of raw material ethylene supplied (for example, 5 to 30 tons/hour, preferably 10 to 20 tons) compressed in the range of the discharge pressure of the secondary compressor (for example, 100 to 300 MPa, preferably 150 to 250 MPa, more preferably 160 to 220 MPa). / hour, more preferably 14.0 to 18.0 tons / hour) can be supplied from the pipe 3 to the temperature zone 1 of the tank reactor 6;
The pressure of the tank reactor 6 can be 155-215 MPa;
Inside the tank reactor 6, there are two temperature zones, temperature zones 1 and 2 are present from the top, and a thermometer can be inserted in each temperature zone;
A polymerization initiator (eg, t-butylperoxy-2-ethylhexanoate) is supplied from piping 4 to temperature region 1 of tank reactor 6 at, for example, 1 to 10 kg/hour, preferably 1 to 8 kg/hour, and more. can be fed preferably from 3.0 to 6.0 kg/hour;
Ethylene is polymerized by raw material ethylene supplied from pipe 3 to temperature region 1 of tank reactor 6 and polymerization initiator (eg, t-butylperoxy-2-ethylhexanoate) supplied from pipe 4. polyethylene is produced. The polyethylene produced in temperature zone 1 and unreacted ethylene are sent to temperature zone 2, where ethylene continues to be polymerized to produce polyethylene;
The polyethylene produced in the temperature zone 2 of the tank reactor 6 and unreacted ethylene are discharged from the bottom of the tank reactor 6 and introduced into the heat exchanger and the separator through the pressure control valve 5, where the polyethylene produced in the separator is and unreacted ethylene to obtain the product polyethylene.

<Method for measuring physical properties of polyethylene>
The physical properties of the polyethylenes produced in Examples and Comparative Examples below were measured according to the following methods.

(1) Melt flow rate (MFR, unit: g/10 minutes)
The melt flow rate was measured by Method A under the conditions of a load of 21.18 N and a temperature of 190° C. in the method specified in JIS K7210-1995.

(2) Density (unit: kg/m ³ )
After annealing according to JIS K6922-2, measurement was performed by method A according to the method specified in JIS K7112.

（試料溶液調製条件）
溶媒：オルトジクロロベンゼン（和光純薬工業株式会社製、特級）にＢＨＴを０．１ｗ／Ｖ（０．１ｇ／１００ｍＬ）の濃度で添加して使用した。
試料溶液濃度：１ｍｇ／ｍＬ
溶解用自動振とう器：ＤＦ－８０２０（東ソー株式会社製）
溶解条件：５ｍｇの試料を１０００ｍｅｓｈのＳＵＳ製の金網袋に封入し、試料を封入した金網袋を試験管に入れ、試験管に５ｍＬの溶媒を加え、試験管にアルミホイルで蓋をし、試験管を浸とう器にセットし、６０往復／分の撹拌速度で１４０℃で１２０分間撹拌した。 (3) Weight fraction of components with Log ₁₀ M exceeding 5.25 (W _{Log 10M > 5.25} , unit: wt%) (M represents polyethylene equivalent molecular weight)
The molecular weight distribution of polyethylene and various polyethylene equivalent molecular weights (number average molecular weight Mn, weight average molecular weight Mw) are determined by gel permeation chromatography (GPC). GPC measurement is performed under the following conditions. Based on the description of ISO16014-1, define the baseline on the chromatogram and designate the peaks. The weight fraction of components with a Log ₁₀ M greater than 5.25 (W _Log10M>5.25 [wt %]) (M represents the polyethylene equivalent molecular weight) is calculated from the integral distribution (see FIG. 5). W _Log10M>5.25 [% by weight]=(integrated value of the integral distribution curve in the portion where _Log10M >5.25)/(integrated value of the entire integral distribution curve).
(GPC equipment and software)
Apparatus: HLC-8321GPC/HT (manufactured by Tosoh Corporation)
(Measurement condition)
GPC column: TSKgel GMHHR-H(S)HT 7.8 mm I.D. D. × 300 mm (manufactured by Tosoh Corporation) 3 Mobile phase: Dibutyl hydroxytoluene (BHT) is added to ortho-dichlorobenzene (manufactured by Wako Pure Chemical Industries, Ltd., special grade) at a concentration of 0.1 w / V, that is, 0.1 g / 100 mL. Flow rate: 1 mL/min Column oven temperature: 140°C
Autosampler temperature: 140°C
System oven temperature: 40°C
Detection: Differential Refractive Index Detector (RID)
RID cell temperature: 140°C
Sample solution injection volume: 300 μL
Standard materials for GPC column calibration: Tosoh Corporation standard polystyrene was weighed out in the combinations shown in the table below, added with 5 mL of ortho-dichlorobenzene (same composition as the mobile phase), and allowed to stand at room temperature for 120 minutes to dissolve. prepared

(Sample solution preparation conditions)
Solvent: BHT was added to ortho-dichlorobenzene (manufactured by Wako Pure Chemical Industries, Ltd., special grade) at a concentration of 0.1 w/V (0.1 g/100 mL).
Sample solution concentration: 1 mg/mL
Automatic shaker for dissolution: DF-8020 (manufactured by Tosoh Corporation)
Dissolution conditions: 5 mg of sample is enclosed in a 1000 mesh SUS wire mesh bag, the wire mesh bag containing the sample is placed in a test tube, 5 mL of solvent is added to the test tube, the test tube is covered with aluminum foil, and the test is performed. The tube was placed in an immersion vessel and stirred at 140° C. for 120 minutes at a stirring speed of 60 reciprocations/minute.

(4) Calculation of light scattering area ratio (R _LS ) The light scattering area ratio was calculated by using a liquid chromatography (LC) device equipped with a light scattering detector, and the polyethylene of each example and each comparative example was treated with ortho-dichlorobenzene. Light scattering area LS of a solution dissolved in 2 mg / mL concentration and Tosoh Corporation standard polystyrene F10 (number average molecular weight 1000) dissolved in orthodichlorobenzene at a concentration of 2 mg / mL Light scattering area LS of a solution ' was measured and calculated from the following formula.
R _LS =LS/LS' (equation 1)
The larger the light scattering area ratio (R _LS ), that is, the larger the light scattering area LS of the solution obtained by dissolving polyethylene in ortho-dichlorobenzene, the larger the amount of ultrahigh molecular weight components in polyethylene.

Measurement conditions are shown below.
・ LC device: HLC-8121GPC / HT (manufactured by Tosoh Corporation)
- Light scattering detector: PD2040 (manufactured by Precision Detectors)
・Laser light source: wavelength 685 nm
・ GPC column: None ・ Sample solution concentration: 2 mg / mL
・Injection volume: 300 μL
・Measurement temperature: 140°C
・Dissolution conditions: stirring for 2 hours at 145 ° C. ・Automatic shaker for dissolution: DF-8020 (manufactured by Tosoh Corporation)
- Solvent and mobile phase: ortho-dichlorobenzene containing 0.1 w/V BHT (manufactured by Wako Pure Chemical Industries, Ltd., special grade)
・ Mobile phase flow rate: 1.0 mL / min

Specifically, the LC apparatus was connected to a light scattering detector (LS). The scattering angle used for light scattering detection was 90°. The LS was placed inside the column oven of the LC apparatus.
The dissolution of the sample was performed according to the following procedure in detail. First, 40.0 mg of sample and 20.0 mL of solvent are put in a 30 mL screw vial and sealed, the screw vial is set in DF-8020 (manufactured by Tosoh Corporation), and the sample is stirred at 140 ° C. for 2 hours. was dissolved. Prior to analysis, the sample solution obtained by the above method was filtered using cylindrical filter paper with a pore size of 10 μm (Whatman cylindrical filter paper, diameter 18 mm×length 55 mm, model number: 2800-185). Filtration is performed at 140°C or higher to avoid precipitation of the sample. After soaking the cylindrical filter paper in the sample solution and allowing it to stand still for 5 minutes to equilibrate, the sample solution leached into the cylindrical filter paper is subjected to analysis. did. Filtration was performed within 20 minutes in order to avoid concentration change of the sample solution due to evaporation of the solvent.
A GPC column and a guard column were not used in order to avoid trapping of ultra-high molecular weight components on the column. In addition, for obtaining a chromatogram, a SUS pipe with an inner diameter of 0.75 mm and a length of 5 m was attached between the sample injection part and the LS detector, and the temperature of the sample injection part and each detector was set to 140 ° C. .
Baseline processing was performed on the obtained LS chromatogram, and the light scattering area was calculated (see FIG. 6).
Data processing software OmniSEC (version 4.7) from Malvern was used to determine the light scattering area.

(5) Film formability evaluation of polyethylene A blown film is formed under the following processing conditions. During molding, the take-up speed is increased stepwise until the bubble is broken, and the thickness and haze of the film formed at a take-up speed 0.5 m/min lower than the breakage speed are measured.
Processing equipment: EX-50 type manufactured by Placo Co., Ltd. Screw diameter: 50mmΦ
L/D: 28
Die diameter: 125mmφ
Lip gap: 2.0mm
Set temperature: 150°C
BUR: 2.0
Take-up speed: 12m/min to 90m/min
Discharge rate: 23kg/h
Take-up machine: IFA-600 manufactured by Tomy Machine Industry Co., Ltd.
A constant take-up speed is maintained for 5 minutes, and if bubbles do not break, the take-up speed is increased by 0.5 m/min. When the bubble breaks, the broken portion is sampled, and if a fish eye (FE) nucleus is visually observed around the broken portion, the breakage is judged to be caused by FE, and the evaluation is performed again. Repeat evaluations until no FE is seen and the bubble bursts.

(6) Haze The haze (unit: %) of the molded blown film was measured according to ASTM1003. A higher haze indicates that the film is easier to handle because it is less likely to wrap (stick together).

(7) Thickness The thickness (unit: μm) of the molded inflation film was measured according to JIS Z1702. Measurements were taken once around the cylindrical film at intervals of 2 cm in the direction perpendicular to the film take-up direction during film formation, and the average value was obtained. A smaller measured value of thickness contributes to the thinning of the polyethylene, indicating that the stretchability of the polyethylene is excellent.

[Examples and Comparative Examples]
The present invention will now be described with reference to examples and comparative examples.

ヘイズが大きいほど、フィルムが取り扱い易いことを示し、厚みが小さいほど（すなわち、厚みの逆数（１／厚み）が大きいほど）、延伸性に優れることを示すので、「ヘイズ／厚み」が大きいほど、薄膜化（延伸性）と取扱い易さ（フィルムのヘイズ）のバランスに優れていることを意味する。表１Ａに示すように、実施例１～５では、「ヘイズ／厚み」は１．２以上であるのに対し、比較例１～４では、１．２未満である。実施例１～５は、比較例１～４に比べて、薄膜化（延伸性）と取扱い易さ（フィルムのヘイズ）のバランスに優れていることが確認された。 Table 1 shows physical properties of the polyethylenes prepared in Examples 1 to 5 and Comparative Examples 1 to 4 below.

The larger the haze, the easier the film is to handle, and the smaller the thickness (that is, the larger the reciprocal of the thickness (1/thickness)), the more excellent the stretchability. , means an excellent balance between thinning (stretchability) and ease of handling (film haze). As shown in Table 1A, Examples 1-5 have a "haze/thickness" of 1.2 or more, while Comparative Examples 1-4 have a "haze/thickness" of less than 1.2. It was confirmed that Examples 1 to 5 are superior to Comparative Examples 1 to 4 in the balance between thinning (stretchability) and ease of handling (film haze).

Examples 1, 2, 3 and Comparative Examples 1, 2, 3, 4 (Example and Comparative Example in FIG. 1)
In FIG. 1, raw material ethylene compressed to a secondary compressor discharge pressure of 171.5 to 211.2 MPa (listed in Table 2) with a total feed amount of 16.0 to 17.7 tons/hour (listed in Table 2). Ethylene is supplied from pipe 9 to temperature region 1 of tank reactor 20 through pipe 10 at a feed rate of 4.0 to 4.4 tons/hour (described in Table 2) above tank reactor 20. , to the temperature zone 3 of the tank reactor 20 through the pipe 11, the feed ethylene is supplied to the bottom of the tank reactor 20 at a rate of 8.0 to 8.9 tons/hour (listed in Table 2). The raw material ethylene supplied from the upper part of the remaining tank reactor 21 at an amount of 4.0 to 4.4 t/hour (listed in Table 2) is supplied through the pipe 12 to the temperature zone 5 of the tank reactor 21. be.
The tank reactor 20 has a pressure of 155.1 to 197.3 MPa, and the tank reactor 21 has a pressure of 134.6 to 177.1 MPa.
Inside the tank reactor 20, there are four temperature zones, temperature zones 1, 2, 3 and 4 from the top, and a thermometer is inserted in each temperature zone.
Further, inside the tank reactor 21, there are four temperature zones, temperature zones 5, 6, 7 and 8 from the top, and a thermometer is inserted in each temperature zone.
In temperature region 1 of tank reactor 20, t-butylperoxy-2-ethylhexanoate, which is a polymerization initiator, is supplied from pipe 13 to the upper part of tank reactor 20 in an amount of 3.5 to 5.5. 1 kg/hour (listed in Table 2) is supplied, and t-butylperoxy-2-ethylhexanoate, which is a polymerization initiator, is supplied to the temperature zone 3 of the tank reactor 20 from the pipe 14 to the tank reactor 20. A lower polymerization initiator feed rate of 3.5-5.2 kg/h (listed in Table 2) is fed.
In addition, t-butylperoxy-2-ethylhexanoate, which is a polymerization initiator, is supplied from the pipe 15 to the temperature region 5 of the tank reactor 21 in an amount of 2.3 to 2.3 to the upper part of the tank reactor 21. 3.9 kg/hour (listed in Table 2) is supplied, and t-butylperoxy-2-ethylhexanoate, which is a polymerization initiator, is supplied from a pipe 16 to the temperature region 7 of the tank reactor 21 for the tank reaction. A polymerization initiator is supplied at a rate of 0.0 to 1.7 kg/hour (listed in Table 2) at the bottom of the vessel 21 .

Ethylene is polymerized by the raw material ethylene supplied from the pipe 10 to the temperature zone 1 of the tank reactor 20 and the polymerization initiator t-butylperoxy-2-ethylhexanoate supplied from the pipe 13 to produce polyethylene. is generated. The polyethylene produced in the temperature zone 1 and unreacted ethylene are sent to the temperature zone 2 and continuously polymerized. The polyethylene produced in temperature zone 2 and unreacted ethylene are sent to temperature zone 3 .
Raw material ethylene and t-butylperoxy-2-ethylhexanoate as a polymerization initiator are further supplied from pipe 11 and t-butylperoxy-2-ethylhexanoate, which is a polymerization initiator, from pipe 11 to temperature region 3, and ethylene is continuously polymerized to produce polyethylene. The polyethylene produced in temperature zone 3 and unreacted ethylene are sent to temperature zone 4, where ethylene is continuously polymerized to produce polyethylene.
The polyethylene and unreacted ethylene produced in the temperature region 4 of the tank reactor 20 are discharged from the bottom of the tank reactor 20, introduced into the heat exchanger 18 through the pressure control valve 17, and cooled in the heat exchanger 18, It is supplied to the temperature zone 7 of the tank reactor 21 .

Ethylene is polymerized by the raw material ethylene supplied from the pipe 12 to the temperature region 5 of the tank reactor 21 and the polymerization initiator t-butylperoxy-2-ethylhexanoate supplied from the pipe 15 to produce polyethylene. is generated.
The polyethylene produced in the temperature zone 5 and unreacted ethylene are sent to the temperature zone 6 and continuously polymerized. The polyethylene produced in temperature zone 6 and unreacted ethylene are sent to temperature zone 7 .
The temperature zone 7 is supplied with cooled polyethylene and unreacted ethylene discharged from the bottom of the tank reactor 20 and introduced into the heat exchanger 18 through the pressure regulating valve 17 and unreacted ethylene. -Butyl peroxy-2-ethylhexanoate is further fed to continue the polymerization of ethylene to produce polyethylene. The polyethylene produced in the temperature zone 7 and unreacted ethylene are sent to the temperature zone 8, where the ethylene is continuously polymerized to produce polyethylene.

The polyethylene produced in the temperature zone 8 of the tank reactor 21 and unreacted ethylene are discharged from the bottom of the tank reactor 21 and introduced into the heat exchanger and separator through the pressure control valve 19, where the polyethylene produced in the separator is and unreacted ethylene to obtain the product polyethylene.

Table 2 shows the manufacturing conditions of Examples 1-3 and Comparative Examples 1-4.

Table 3 shows the temperature [°C] and the temperature difference (ΔT) [°C] in each temperature range of Examples 1, 2 and 3.

Table 4 shows the temperature [°C] and the temperature difference (ΔT) [°C] in each temperature range of Comparative Examples 1, 2, 3 and 4.

Examples 4 and 5 (Example in FIG. 2)
In FIG. 2, raw material ethylene compressed to a secondary compressor discharge pressure of 166.9 to 167.0 MPa (listed in Table 5) with a total feed amount of 14.3 to 17.0 tons/hour (listed in Table 5). Ethylene is supplied from pipe 5 to temperature region 1 of tank reactor 11 through pipe 6 at a feed rate of 7.2 to 8.5 tons/hour (described in Table 5) above tank reactor 11. , to the temperature zone 3 of the tank-type reactor 11 through a pipe 7, and supplied to the bottom of the tank-type reactor 11 at a feed rate of 7.2 to 8.5 kg/hour (listed in Table 5).
The tank reactor 11 has a pressure of 164.2 MPa.
Inside the tank reactor 11, there are four temperature zones, temperature zones 1, 2, 3 and 4 from the top, and a thermometer is inserted in each temperature zone.
In temperature region 1 of tank reactor 11, t-butylperoxy-2-ethylhexanoate, which is a polymerization initiator, is supplied from pipe 8 to the upper part of tank reactor 11 at a polymerization initiator supply amount of 3.7 to 3.5. 9 kg/hour (listed in Table 5), and t-butylperoxy-2-ethylhexanoate, which is a polymerization initiator, is supplied from pipe 9 to temperature zone 3 of tank reactor 11 to tank reactor 11. A lower polymerization initiator feed rate of 2.2-2.6 kg/h (listed in Table 5) is fed.

Ethylene is polymerized by the raw material ethylene supplied from the pipe 6 to the temperature zone 1 of the tank reactor 11 and the polymerization initiator t-butylperoxy-2-ethylhexanoate supplied from the pipe 8 to polyethylene. is generated. The polyethylene produced in the temperature zone 1 and unreacted ethylene are sent to the temperature zone 2 and continuously polymerized. The polyethylene produced in temperature zone 2 and unreacted ethylene are sent to temperature zone 3 . Raw material ethylene and t-butylperoxy-2-ethylhexanoate as a polymerization initiator are further supplied from pipe 7 and t-butylperoxy-2-ethylhexanoate, which is a polymerization initiator, from pipe 7 to temperature region 3, and ethylene is continuously polymerized to produce polyethylene. The polyethylene produced in temperature zone 3 and unreacted ethylene are sent to temperature zone 4, where ethylene is continuously polymerized to produce polyethylene.

The polyethylene produced in the temperature zone 4 of the tank reactor 11 and unreacted ethylene are discharged from the bottom of the tank reactor 11 and introduced into the heat exchanger and separator through the pressure control valve 10, where the polyethylene produced in the separator is and unreacted ethylene to obtain the product polyethylene.

The manufacturing conditions for Examples 4 and 5 are shown in Table 5.

Table 6 shows the temperature [° C.] and the temperature difference (ΔT) [° C.] in each temperature range of Examples 4 and 5.

According to the present invention, by setting the ratio of the middle to high molecular weight component amount and the ultra high molecular weight component amount of polyethylene to a specific range, thinning (stretchability) and ease of handling (irregularities on the film surface, for example, film haze) can be provided.
Applications of the polyethylene of the present invention include a wide variety of films such as heavy bags, shrink wrap, general packaging, thin films, protective films (protective films), extrusion laminate films, extrusion films, and foamed films. It is suitable for applications such as various parts, various housing equipment parts, various industrial parts, various building material parts, and various automobile interior and exterior parts. It has high applicability in the field.
In the method and apparatus for producing polyethylene of the present invention, the pressure inside the reactor and the temperature difference in the reaction zone inside the reactor can be appropriately controlled.

Claims (4)

In the integral distribution curve of polyethylene evaluated by gel permeation chromatography, the weight fraction of components with Log ₁₀ M exceeding 5.25 (W _Log10M>5.25 : unit is wt%) and (M is polyethylene conversion molecular weight),
A polyethylene having a ratio (W _Log10M>5.25 /R _LS ) to a light scattering area ratio (R _LS ) represented by the following (Formula 1) of 5.7 or more and 6.7 or less.
R _LS =LS/LS' (equation 1)
(In the formula, LS indicates the light scattering area of a solution obtained by dissolving 40 mg of the polyethylene in 20 mL of ortho-dichlorobenzene.
LS' indicates the light scattering area of a solution in which 40 mg of standard polystyrene having a number average molecular weight of 1000 is dissolved in 20 mL of ortho-dichlorobenzene. ) 2. The polyethylene of claim 1, wherein W _Log10M>5.25 /R _LS is 5.8 or more and 6.6 or less. 3. Polyethylene according to any one of claims 1 or 2, wherein the polyethylene is a high pressure low density polyethylene. The polyethylene according to any one of claims 1 to 3, wherein said polyethylene has a melt flow rate (MFR) of 2 to 6 g/10 min.

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