JPS6026051A - Polyethylene composition - Google Patents

Abstract

PURPOSE:To provide a polyethylene compsn. having excellent extrudability, impact resistance, etc. and suitable for use in extrusion, by blending polyethylene obtd. by polymn. in the presence of a Ziegler catalyst, with polyethylene composed of both high-molecular and low-molecular moieties. CONSTITUTION:96-60wt% polyethylene (A) which is obtd. by (co)polymerizing ethylene by a two-stage polymn. method and is composed of a low-molecular moiety having an MW of 5,000-90,000 and a high-molecular moiety having an MW of 100,000-1,500,000 in a weight ratio of the low-molecular moiety to the high-molecular moiety of 70/30-30/70 and in which the ratio of the MW of the high-molecular moiety to that of the low-molecular moiety is 4-200, is mixed with 4-40wt% polyethylene (B) having an MW of 50,000-500,000 and a density of 0.91-0.94g/cm<3> obtd. by (co)polymerization in the presence of a Ziegler catalyst to obtain the desired polyethylene compsn.

Description

Detailed Description of the Invention The present invention relates to a polyethylene composition having excellent molding processability, mechanical and chemical properties, particularly molding processability such as extrudability and melt viscoelasticity, and impact resistance. This invention relates to a polyethylene composition which has excellent physical properties such as ring stress cracking resistance (hereinafter referred to as B8OR) and is particularly suitable for extrusion acid type applications.

For applications such as polyethylene profile extrusion and non-isolated molding, polymers with relatively high molecular weights, 1-molecule distribution, and wide distribution are suitable.

Several methods have been proposed as methods for producing polyethylene with a wide molecular weight distribution.

As one method, a method of mixing high molecular weight polyethylene and low molecular weight polyethylene has been proposed (%KOKAI 4FI-3215, JP 45-22007, JP 54-100444, JP 54-100445, JP 54-161657, JP 55-60542, JP 55-60543, JP 56-57841, JP 57-133136).

In addition, as another method, a multi-stage polymerization method of two or more stages has been attempted (Japanese Patent Publication No. 46-11349, Japanese Patent Publication No. 48-42
716, JP-A-51-47079, JP-A-52-197
88>.

Polymers produced by these methods have a wide molecular weight distribution and good Eson.

When the inventors of the present application examined some of the examples shown above, they found that the molecular weight distribution was wide and the mouth B8OR was improved, but on the other hand, those polyethylenes had low impact strength and were further difficult to mold. It has been found that there are a number of drawbacks in terms of practical properties, such as poor melt viscoelastic properties at the time of molding, prone to uneven thickness in molded products, and inability to mold molded products with complex shapes.

The present invention aims to improve the various drawbacks of polyethylene obtained by the above-mentioned known methods, and at the same time provide a polyethylene composition that has excellent overall moldability and physical properties.

That is, the present invention consists of polyethylene (A) selected from the group of homopolymers of ethylene and copolymers of ethylene and α-olefins, and polyethylene (B) selected from copolymers of ethylene and α-olefins. It is a polyethylene composition, (n polyethylene (A) has a low molecular weight part (A-L) in which the molecule 1 is 0.5 to 90,000, and a high molecular weight part (A-H) in which the molecular weight is 100,000 to 1.5 million. The molecular weight of (A-H) [1: / (A-L) is between 4 and 200, and the amount of (A-L) to 1 of (A-H) is the weight ratio. 70-30 to 30-70
(1) Polyethylene (B) is polymerized using a Ziegler type catalyst, and the molecule 1" of (B) is from 50,000 to 50,000
00,000, and the density is 0.91 g/am” to 0.94
g/cml, and 1 of (B) in the composition ranges from 4 to 40% by weight.

The present invention has a wide range of industrial applicability, especially melt extensibility, shape retention, rigidity, impact resistance, B5OR, etc.
Polyethylene compositions suitable for various uses such as various pipe molded products, profile extrusion molded products, and coating materials that require excellent moldability and physical properties, as well as maintenance of high-level physical properties over a long period of time.5- This is what we provide.

The present invention will be explained in detail below.

Polyethylene (A), which is a constituent component of the present invention, is selected from the group of homopolymers of ethylene and copolymers of ethylene and α-olefins.

Polyethylene (B) is selected from the group of copolymers of ethylene and α-olefin.

The a-olefin used in the copolymerization has 3 to 14 carbon atoms, and examples thereof include propylene, butene, pentene, hexene, 4-methylpentene-1, octene, and decene.

Polyethylene (A) is a polyethylene consisting of a low molecular weight part (A-L) and a high molecular weight part (A-H), but the molecular weight (M Wa -t, ) of (A-L) is 0.5 million. The molecular weight (MWA-H) of (λ-H) is from 100,000 to 1
It is 500,000. If MWA-L is less than 50,000, the uniform dispersibility and physical properties of each component will deteriorate, while if it exceeds 90,000, the molecular weight of the composition will be within an appropriate range and the molecular I' distribution will be widened.
This results in a decrease in workability. More preferably, it is 10,000 to 70,000. On the other hand, when the MW is less than 100,000, the molecular weight of the composition decreases and the gsoa also decreases. 1
If it exceeds 500,000, fish eyes may occur and the uniform dispersibility of each component in the composition may deteriorate, resulting in poor processability and physical properties. More preferably 150,000~
It's 1 million.

Also, the ratio of MW^-H to MWmu-L (MWmu-II/
MWA-L) is 4 to 200; if it is less than 4, the molecular weight distribution is narrow and processability is low, making it impossible to obtain the excellent physical properties of the present invention.

On the other hand, if it exceeds 200, there is no advantage in improving moldability and physical properties, and it is also disadvantageous in manufacturing. More preferably it is 7-150.

In addition, the density of A-L is 0.91 to 0,98 g/cm
3, the density of A, -H is 0.91 to 0.97 g/c
m''. The density of A-H is lower than both of A-L and polyethylene (B), and is 0.91 to 0.
When it is 95 g/cm 3 , both processability such as extrudability, physical properties such as impact resistance and B8OR are improved, which is preferable.

Polyethylene (A) ranges from 70:30 to 30:70, preferably 6
It ranges from 0:40 to 40:60.

If the amount of A, -H exceeds 70%, the molecular weight distribution will be narrow (processability and physical properties will be unbalanced).

The method for producing N+1 ethylene (A-) includes a method of mixing 1 part of the low molecular weight part and 1 part of the high molecular weight part in advance, or a method of mixing the low molecular weight part and 1 part of the high molecular weight part in advance. There are methods such as polymerization using a plated car.Industrially, a two-stage polymerization method is preferred.In addition, for 28 lbs. desirable.

Polyethylene (B) is the molecule #1! : (MWn) is 50,000 to 500,000, density is 0.91 g/cm3 to (
1,94 g/cm". A particularly desirable embodiment is M
W n is 70,000 to 400,000, and M W s / M
W A-L is 1.5 or more, and MW M-g/M
W s is 1.5 or more and the density is 0.915 to 0
, 935 g/cm".When the MWi+ and density are within these ranges, various performances such as moldability, rigidity, impact resistance, B5OR, etc. are in a balance i~, suitable for the above extrusion molding applications. It becomes a composition.

In addition, the amount of polyethylene (B) in the composition is 4 by weight.
The ratio is between 1 and 40, preferably 8% and 30
Section below. If it is 40% by weight or more, the molecular weight distribution becomes narrow and the processability decreases L, EsoR.

Rigidity etc. also decreased [2 unfavorable]. If it is less than 4% by weight, the effect of using polyethylene (B) fK is low. Also,
The copolymerized olefin used for (B)]7 is,
Those having 4 or more carbon atoms are preferred, such as butene, hexene, 4
Methylpentene, octene, decene, etc. are preferable. especially,
Hexene, 4-methylpentene, and octene are preferred from the viewpoint of composition performance and industrial productivity.

The polyethylene (A) is polymerized using a transition metal catalyst such as a Ziegler type catalyst or a chromium compound catalyst. In (A), both the low molecular weight part and the high molecular weight part are polymerized with the same type of transition metal catalyst, or the low molecular weight part and the high molecular weight part are polymerized with different transition metal catalysts. Although selected from the group, particularly preferred is one in which both the low molecular weight part and the high molecular weight part are produced by a magnesium compound-based Ziegler type catalyst -9=.

The polyethylene (B'l) is produced using a thousand-dollar type catalyst, but particularly preferred is one produced using a magnesium compound-based Ziegler type catalyst, which eliminates the decatalyst step. The polyethylene CB) produced by the Ziegler-type catalyst is characterized by a relatively narrow molecular weight distribution, which increases the effects aimed at in the present application.

Magnesium compound-based Daegler-type catalysts include inorganic,
Magnesium, '1g@, any system based on magnesium is preferred.

For example, magnesium chloride, hydroxymagnesium chloride, magnesium oxide, magnesium hydroxide, magnesium carbonate, magnesium alkoxide, organic acid salts of magnesium, complexes of these with electron-donating compounds such as alcohols and organic acid esters, or complexes of these with electron-donating compounds such as alcohols and organic acid esters. mixtures, organomagnesium compounds having carbon-magnesium bonds, such as dialkylmagnesiums, alkylmagnesium chlorides, alkylmagnesium alkoxides, alkylmagnesium siloxides, or mixtures of these organomagnesium compounds with electron donors such as ethers. Complexes or N reaction products of these organic magnesium components and halides, such as hydrochloric acid, chlorinated hydrocarbons, silicon tetrachloride, and tin tetrachloride, are used as the magnesium component, and this is combined with titanium and/or vanadium compounds. A catalyst consisting of a component made by reacting the above with an organometallic compound is used.

Particularly preferred catalysts in the present invention: 1. So, for example, (1) general formula MffMgβ”P R2qXr Y
s (where α is 0 or a number greater than 0, l) +
Q, r + 8 is 0 or a number larger than 0, p +
The relationship is q1r1s2rr+a+2β, where M is a metallic element belonging to group Ⅰ or group 4 of the periodic table, and 几1. Bj is a hydrocarbon group having the same or different number of carbon atoms, x and y are the same or different groups, halogen, 0 approximately 3.08
i R' R5Rfi.

N几'R' + S R' represents a group, R3+
R'+It5+R'+B7, B11 represents a hydrogen atom or a hydrocarbon group, R9 represents a hydrocarbon group); and (g) at least one
a titanium or nonadium compound containing halogen atoms, and (m) A7, B.8 i*Ge
+ Sn + Te + Sb halide compound (1
)~(if,,), (1) and (1) or (1)
A solid catalyst component (A) obtained by reacting 0) and (1)
and an organometallic compound CB). The organometallic compound CB) is a compound belonging to Groups 1 to 3 of the periodic table, and in particular, a complex containing an organoaluminum compound and an organomagnesium compound is preferable.

The reaction between the catalyst component CA) and the organometallic compound CB) is as follows:
Adding both components to the polymerization system (-1 It is possible to carry out the process as the polymerization progresses under polymerization conditions, or it may be carried out in advance prior to the polymerization. Also, the reaction ratio of the catalyst components is
CB) component 1 to 3000 mmo per 1 g of [A] component
It is preferable to carry out the process within the range of j.

Instead of the catalyst component (A), a Ti compound supported on an inorganic Mg compound may be used.

Among these catalyst examples, particularly desirable ones are:
Tokuko Sho 52-36788.52-36790.52-3
6791, 52-36792, 52-5007 (1,5
2-36794, 52-36795, 52-36796
, 52-36915, 52-36917, 53-601
9, Japanese Patent Publication No. 50-21876.50-31835.50
--72044.50-78619.53-40696
There is one with the number.

The polyethylenes (A) and (B) are produced by methods such as suspension polymerization, solution polymerization, and gas phase polymerization.

Although it is industrially preferable to produce the polyethylene (A) shell by two-stage polymerization, several two-stage polymerization methods have already been proposed. Examples of preferred methods used in the present invention are described below.

The polymerization is carried out in saturated hydrocarbons having 4 to 10 carbon atoms. The order of polymerization may be (A-L)-(λ-H) or (A-H)-(λ-L).

For the sake of simplicity, the .xi. turn of (A-L)-(A-H) will be explained with reference to FIG. 1 of the drawings.

The low molecular weight part (A-i,) has a polymerization pressure of 1 to 30 Kg/c.
The polymerization rate is preferably 3 to 25 Kg/am2G, and the polymerization temperature is 60 to 100°C, preferably 70 to 90°C. The high molecular weight part (A-H) has a polymerization pressure of 0.5 to 30
Kg/crn”G, preferably 0.5-20 Kg/
cm''G, and the polymerization temperature is 40-110°C, preferably 60-90°C.

In the polymerization vessel (1), ethylene, hexane, hydrogen, catalyst components, etc. are supplied from the line (2), and low molecular weight polyethylene (A-L) is polymerized. The slurry in the polymerization vessel (1) is led to a flash drum (3) to remove unreacted ethylene and hydrogen. The removed ethylene and hydrogen are pressurized by a compressor (4)K and returned to the polymerization vessel (1). On the other hand, the slurry in the flash drum (3) is introduced into the second stage polymerization vessel (6) by the pump (5). In the polymerization vessel (6), ethylene, comonomer, hexane, catalyst components, etc. are supplied from the line (7), polymerization of high molecular weight polyethylene (A-H) is carried out, and the polymer in the polymerization vessel (6) is converted into a product. It is taken out after a transfer process.

The flow explained above is one of the typical examples of the present invention, and in some cases, high molecular weight 14 parts (A-H) are polymerized in the polymerization vessel (1), and low molecular weight parts (A-H) are polymerized in the polymerization vessel (6). Part (A
-L) may be polymerized. In that case, it is possible to omit the flash drum (3). Furthermore, the contents of the polymerization vessel may be circulated from the latter stage polymerization vessel (6) to the former stage polymerization vessel (1).

Such a flow sheet allows polyethylene (
A) polymerization can be carried out.

The polyethylene (A) and (B) are mixed and kneaded to form the desired polyethylene composition.

As for the mixing method of polyethylene (A) and polyethylene (B), usual methods such as powder state, slurry state, pellet state, etc. are used. Kneading is carried out at a temperature of 150 to 300C using a -shaft or twin-screw extruder, kneader, etc.

The melt index (hereinafter referred to as MI) of the polyethylene composition produced in this way is 0.001 g
/ 10 min to 10 g/10 m1n depending on the application. In particular, M is a composition suitable for extrusion molding and
I is 0.01 g/10 min to 0.5 g 7
In the range of 10 m in, the density is 0.935 g 7c
m” to 0.955 g/cmj, respectively.

The polyethylene composition contains substances that can be added or blended with polyolefins, such as heat stabilizers, antioxidants, ultraviolet absorbers, pigments, antistatic agents, lubricants, fillers, other polyolefins, thermoplastic resins, rubbers, etc. , can be used as needed. However, it is also possible to mix a foaming agent and perform foam molding.

The features of the polyethylene composition obtained by the present invention are summarized below.

(1) It has a good balance between flow characteristics and melt viscoelasticity when melted, allows molding of complex shapes with uniform thickness, and has good shape retention.

(2) It has excellent physical properties such as impact resistance, rigidity, and ESOR, and has excellent durability and maintains high-level physical properties over a long period of time even in various high- and low-temperature environments and in contact with chemicals. ) It has excellent physical properties and processability, making it easy to make thin-walled molded products. This product is suitable for the era of resource saving and energy saving.

(4) Easy to manufacture.

(5) It is particularly suitable for applications such as profile extrusion molding, pipes, and coatings, but can also be applied to various molding applications such as hollow molding, film molding, injection molding, stretching, rotation, and foaming.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples in any way.

Symbols, measurement methods, and measurement conditions shown in Examples and Comparative Examples.

(1) MI: represents melt index, ASTMI
)-1238, temperature 190C, load 2.16Kp
Values measured under these conditions.

(1) M I R; Load 2 under M I measurement conditions
It means the quotient obtained by dividing the value measured at 1°5 Kf by MI,
This is one measure of molecular weight distribution, and the larger the value, the broader the molecular weight distribution.

(fil) Molecular weight (MW); using decalin solution, 1
The intrinsic viscosity (η) measured at 35C and the formula described in Journal of Polymer Science Vol. 36, p. 91 (1957J), η = 68
I hit W. Note that all molecular weights in the present invention are determined by this method.

Dynamic density: O measured according to A8TMD-1505 (■) Tensile impact strength: Measured according to AsTMn-1822.

(V[) Fi80R; 5 by A8TMD-1693
Measure at 0C.

9:00 Melt extensibility: Using a melt tension tester made by Toyo Seiki ■, stretch the strand that has been melted and extruded with resin at a temperature of 150C, and set the highest drawing speed at which the strand can be stretched without breaking when the strand exits the nozzle. The quotient divided by the linear velocity of

Export) Shape retention: A hollow molded product with an uneven cross-sectional shape as shown in the drawing (Figure 2) was molded with a blow molding machine equipped with a 50mm diameter screw at an extrusion temperature of 1701: and a mold temperature of 30C, Measure the wall thickness and subtract the maximum thickness 18- (tmin) to find the difference value (tmax - tmtn
) divided by the average thickness (tav) times 100. It can be judged that the smaller this value is, the better the shape retention is.

Example 1-1 (1) Ho! J Synthesis of catalyst for ethylene (A) Trichlorosilane (H8iO/1a) 1 mol/l hexane solution e2
It was placed in an autoclave at 8°C and maintained at 50C.

Composition A for this! M g6.6 (021-I5)2.
6 (n-041(9)9.6 (004■19)3.5
2 tons of a 1 mol/l hexane solution of the organoaluminium-magnesium complex was added dropwise over 2 hours with stirring, and the mixture was further reacted at this temperature for 2 hours. The generated solid component is
It was washed twice with 1 part of hexane by the precipitation method. 2 tons of titanium tetrachloride was added to the slurry containing this solid component, and 13
After reacting for 2 hours at 0 [0], the solid catalyst was isolated and washed with hexane until no free halogen was detected. This solid catalyst contained 21% titanium.

(2) Production of polyethylene (A,) by two-stage polymerization First, in order to produce a low molecular weight part, polymerization was carried out in a polymerization vessel (1) having a reaction volume of 300 tons. Polymerization temperature is 83C1 Polymerization pressure is 1
1 K51/Crn” ().This polymerization vessel (1)
Then, the above solid catalyst was added to triethylaluminum Ramura, 407/Hr at a rate of 1.3 mmot (based on TI atoms)/Hr, and 20 mmol (based on metal atoms)/Hr.
Polymerization is carried out by supplying purified hexane at a rate of ) (r), and supplying ethylene at a rate of 7 NM''/l (r and hydrogen as a molecular weight regulator such that the hydrogen concentration in the gas phase is approximately 90 mol %). The content of the polymer slurry in the polymerization vessel (1) was led to a flash drum (3) at a pressure of 9 K9/cm2 (3) and a temperature of 75, and unreacted ethylene and hydrogen were separated.
The slurry is pressurized and introduced into the polymerization vessel (6) using a slurry pump (5). In the polymerization vessel (6), the temperature is 5OC, the pressure is 8 KSI/cm
Polymerization is carried out at 2G. The polymerization vessel 6 has an internal volume of 250 tons. 7.5 m of triethylaluminum was added to the polymerization vessel (6).
40 t/Hr of purified hexane and 7.2 N M of ethylene at a rate of mot (based on metal atoms)/1-ir.
/T(r), and the concentrations of hydrogen and zothene-1 in the gas phase are about 2 mol% and about 2.5%, respectively.
Polymerization was carried out by introducing the polymer in an amount of mol %. The MI of /e powder of the polyethylene (A) obtained from the polymerization vessel (6) after carrying out two-stage polymerization in this way was 0.17 g/
10 rnin.

The density was (1956 g 7 cm").

In addition, from the results of a separate homopolymerization experiment conducted under similar conditions, the molecular weight of the low molecular weight portions (A, -L) of polyethylene (A) was 1-7 in the first stage polymerization vessel (1). Approximately 13.
000, density approximately 0.974 g 7 cm 3. The high molecular weight part (A-H) of polyethylene (A) polymerized in the second stage polymerization vessel (2) has a molecular weight of approximately 540,000, and a density approximately 0.939 g.
Each is estimated to be 7 cm3.

(3) Moon? Production of polyethylene (B) Polyethylene (B) was produced by homopolymerization using a polymerization vessel with a reaction capacity of 200 tons. Polymerization temperature is 73tT
, the polymerization pressure was 11 to 9/crn2G, the catalyst was the same as polyethylene, hydrogen was used as a molecule@regulator, and butene-1 was used as a comonomer. Molecular weight: 200,000, density: o,
It was 927g/-. In addition, MIKeO, 15g/10m
In, MTIL 52.

(4) Production of polyethylene composition-21 = Polyethylene (A) and (B) produced as described above.
) were mixed in a weight ratio of 88:12, and then this mixture was heated and treated with tetrakis[methylene-3-(3', 5'-ti-ti-thi-4'-) as an antioxidant. 500 ppm of hydroxyphenyl)propionate comethane, 1000 pprn of dilauryl 3,3'-thiodizolobionic acid ester, 500 ppm of ditertiarybutylhydroxytoluene, and 11000 ppm of calcium stearate were added, and the mixture was sufficiently stirred and mixed in a Henschel mixer.

This mixture was kneaded using a Farrell FOM at a temperature of 22 Orr, and then this kneaded product was extruded using a single screw extruder at a temperature of 250 C and pelletized to produce a polyethylene composition. As shown in Table 1, this polyethylene resin composition exhibits excellent moldability and physical properties.

Example 1-2 Polyethylene ξ powder (A) produced in Example 1-1
A polyethylene composition was prepared in the same manner as in Example 1-1 except that 22- and (B) were mixed in the amounts shown in Table 1, except that the additives, mixing, kneading, and extrusion conditions were the same as in Example 1-1. Table 1 shows the results of manufacturing and evaluating its performance.

Comparative Example 1-1 The additives added in Example 1-1 were added only to the polyethylene (A) produced in Example 1-1, and the mixture was kneaded and extruded in the same manner as Example 1-1. So, we made polyethylene (A) pellets and evaluated their performance, which gave us a rating of 2.

(Left below) Examples 2-1 to 2-2 (1) Synthesis of catalyst for polyethylene (A) 138 g of di-n-butylmagnesium and 19 g of triethylaluminum
g and raw hebutane 2,/1. By feeding it into a stirring tank with a capacity of 4 t and reacting at 8 oc for 2 hours,
Composition ARM 176 (02115) 3(n -04
H*)+2 organoaluminium-Magui sium complex was synthesized. This complex 400 mmot, (54 g) in n-hebutane containing $-800 me and titanium tetrachloride 40
After removing moisture and oxygen from 800 ml of rhohebutane solution containing 0 mmot by dry nitrogen substitution, -2
01: The reaction was carried out for 4 hours with stirring. The resulting hydrocarbon-insoluble solid was isolated and washed with n-hebutane to yield 106 g of solid.

(2) Production of polyethylene (A) The above catalyst and used in Example 1-1 1. Polymerization was carried out using a two-stage polymerizer using the same polymerization temperature, pressure, catalyst supply rate, and hexane 1 (supply rate) as in Example 1-1, and under the other conditions as follows. Namely, the first stage (low molecular weight part) The polymerization was carried out by supplying ethylene at a rate of 6.1 N M3/Hr25- and hydrogen such that the concentration in the gas phase was about 70 mol%.Then, the polymerization was carried out in a flash drum in the same manner as in Example 1-1. , unreacted ethylene and hydrogen are separated, and in the second stage (high molecular weight part) polymerization, ethylene is converted into 7.5 NM3
/ I-b, hydrogen and butene-1 were introduced so that the concentrations in the gas phase were about 10 mol % and about 4.5 mol %, respectively, and polymerization was carried out.

M of the polyethylene (A) powder thus obtained
I is 0.45 and the density is 0.954 g 7 cm3.

In addition, from a separate instant polymerization experiment conducted under similar conditions,
The low molecular weight portion (A-L) of polyethylene (A) has a molecular weight of approximately 31,000 and a density of approximately 0.972 g/Cm.
, the high molecular weight part (A-11) is estimated to have a molecular weight of about 320,000 and a density of about 0.940 g 7 cm 3 .

(3) Production of polyethylene (B) Using the polymerization vessel and catalyst used to produce polyethylene (B) in Example 1-1, adjusting the molecular weight with hydrogen, and using hexene-1 as a comonomer, the molecular weight was 150,000,
Polyethylene (B) with a density of 0.933 g and 7 cm3 was produced. In addition, MI is 0.4 g / 10 mi
It was n26-MIR44.

(4) Production and evaluation of polyethylene composition The polyethylenes (A) and (n) produced as described above were mixed at the compounding ratio shown in Table 2, and the other compositions were the same as in Example], -1. Polyethylene compositions were produced and evaluated. The performance is shown in Table 2.

Comparative Example 2-1 In Example 2-1, additives were added to only polyethylene (A) in the same manner as in Example 1-1, and polyethylene (A) obtained by kneading was evaluated. The performance is shown in Table 2.

(Margin below)

[Brief explanation of drawings]

The drawings show an example of an embodiment of the present invention, and FIG. 1 is an example of a two-stage polymerization method, and FIG. 2 is a cross-sectional view of a molded article for measuring shape retention in the example. Patent applicant: Asahi Kasei Industries, Ltd. 29- Figure 1 Figure 2

Claims (5)

[Claims] (1) Polyethylene (A
) and polyethylene (B) selected from copolymers of ethylene and α-olefin, (1) Polyethylene (A) has a molecular weight of 0.5 to 9.
Low molecular weight part (A-L) of 10,000 and molecular weight of 100,000 to 150
10,000 high molecular weight parts (A-H), the molecular weight of (A-H)/(A-1,) is 4 to 200, and one pair of (A-L) (A- The amount of H) is 70:3 by weight
The ratio of polyethylene (A) in the composition is 30:70.
) is 96% by weight'i! 0) Polyethylene (B) is polymerized using a Ziegler type catalyst, its molecular weight is 50,000 to 500,000, and its density is 0.91 g/cm3. 0,94
A polyethylene composition characterized in that the amount of polyethylene (B) in the composition ranges from 4 to 40 g/cm3. (2) The polyethylene composition according to claim 1, wherein the polyethylene (A) is produced by two-stage polymerization. (3) The polyethylene composition according to claim 1 or 2, wherein the polyethylene (A) and (B) are produced using a magnesium compound-based Ziegler type catalyst. (4) The molecular weight of polyethylene (B) is from 100,000 to 400,000, the molecular weight of polyethylene (B) molecule i/(A-L) is 1.5 or more, the molecular weight of (A-H)/polyethylene (B) ) has a molecular weight of 1.5 or more.
．． 2. Or the polyethylene composition according to item 3. (5) The density of polyethylene (B) is from 0.915 to 0.
．． 935g/Cm” Claim No. 1.2.3
Or the polyethylene composition according to item 4.