JPS60177008A - Preparation of polyethylene suitabe for high-speed blow molding, having high rigidity - Google Patents

Abstract

PURPOSE:To obtain the titled polymer having improved rigidity and processing properties free from fish eye, by using a catalyst consisting of a reaction product of an oxygen-containing organomagnesium compound and a Ti halide compound, etc. and an organoaluminum compound, polymerizing ethylene under specific condition by two stages. CONSTITUTION:In polymerizing ethylene alone by the use of a catalyst consisting of (A) a reaction product of an oxygen-containing organomagnesium compound and a Ti halide compound, and (B) an organoaluminum compound in a hydrocarbon solvent at 50-100 deg.C, the polymerization reaction is carried out in the first and the second polymerization zones by two stages, ethylene is polymerized in the presence of hydrogen in a molar ratio of hydrogen to ethylene in a gaseous phase of 0.01-1.0 in one of the zones to prepare 30-70wt% based on the total amount of polymer prepared of a polymer having 100,000-700,000 viscosity-average molecular weight, ethylene is polymerized in the presence of hydrogen in a molar ratio of hydrogen to ethylene of 0.1-15 in the other zone to give 70-30wt% polymer having 10,000-40,000 viscosity-average molecular weight, so that the desired polymer having 0.1-1g/10min melt index and 0.965- 9.974g/cc density of the whole polymer is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing polyethylene suitable for blow molding and extrusion molding. More specifically, the present invention relates to a method for producing polyethylene for blow molding and extrusion molding, which has high rigidity, good fish-eye appearance, and excellent moldability by carrying out one-stage polymerization using a specific catalyst under specific conditions.

Conventionally, in the field of blow molding and extrusion molding of polyethylene, it has been necessary to have a high degree of balance between the physical properties and workability of the molded product and to have good fish eyes.

For this reason, various proposals have been made, but one method to produce polyethylene with an excellent balance between molded product properties and processability and with fewer fish eyes is to carry out polymerization in one step using a specific catalyst system. A method has been proposed in which a reaction is carried out and the mixing ratio, molecular weight, etc. of the polymers are specified at that time (Japanese Patent Application Laid-Open No. 2003-120012, A-, 2-30).

It has been shown that by this method, it is possible to obtain polyethylene for blow molding which not only has excellent environmental stress cracking resistance but also has good formability such as extrudability and ballance effect, and has fewer fish eyes. There is. In addition to the above method, we also proposed a method in which impact resistance and environmental stress cracking resistance are further improved by controlling both the first and first stage polymers to a specific degree of copolymerization. It has been done (Tokukaisho!'/
-/! rzaλ//).

However, in recent years, polyethylene suitable for thin-wall molding and high-speed molding has been increasingly sought after from the viewpoint of resource and energy conservation, but the conventional techniques are no longer able to provide sufficient satisfaction. Resins that are suitable for thin-walled molding must have high rigidity so that they can be strong even when made thin.
It is necessary to be able to easily spread thinly and uniformly, and the thinning of the wall also reduces the appearance of fish eyes, which become more noticeable. Resins suitable for high-speed molding are related to the above-mentioned thin-wall moldability, but must not cause the parison to blow out when being blown at high speed during molding, do not cause surface roughness under high shear, and must be able to extrude the molten resin using an extruder. It means having good sex.

The inventors of the present invention have intensively studied the above points, and have found that by carrying out homopolymerization of ethylene under specific conditions using a specific catalyst system, unexpectedly high rigidity can be developed, and thin-wall moldability can be achieved. The present invention was achieved by discovering that it has excellent high-speed moldability and fewer fish eyes.

That is, the gist of the present invention is that (a) a reaction product between an oxygen-containing organic compound of magnesium and a titanium halide compound, or a reaction product between an oxygen-containing organic compound of magnesium, an oxygen-containing organic compound of titanium, and an aluminum halide compound; When homopolymerizing ethylene at a go-iooc temperature in a hydrocarbon solvent using a catalyst system consisting of □ and (b) an organoaluminide metal, (a) the polymerization reaction is carried out in one step, that is, the first reaction. The reaction mixture obtained by polymerization in the zone is polymerized in the first reaction zone, and (b) the mole based on the ethylene in the gas phase is polymerized in either the seventh or first reaction zone. Polymer A is polymerized in the presence of hydrogen at a ratio of 0.0/~8 to 100,000 to 700,000 with a viscosity average molecular weight of 1 to 30 of the total polymer produced.
Polymer B with a viscosity average molecular f of 70,000 to 20,000 is produced in the other zone in the presence of hydrogen with a molar ratio of 80 to 15 to ethylene in the gas phase, with a total weight of 70 to 30 weight of the combined product amount, and further, the viscosity average molecular weight of polymer A/the viscosity average molecular weight of polymer B is 1O-1
IO, and furthermore, (c) both the first and first reaction zones are ethylene homopolymerized, and (b) the melt index of the entire polymer finally produced is o, i~/f/10 min, and the density is 0+9. A j-e0.
The present invention relates to a method for producing polyethylene which is characterized by having a polyethylene of 97'1f10o and is suitable for high-speed blow molding.

To explain the present invention in more detail, the catalyst used in the present invention is (a) a reaction product of an oxygen-containing organic compound of magnesium and a titanium compound, or a reaction product of an oxygen-containing organic compound of magnesium and an oxygen-containing organic compound of titanium. A catalyst system consisting of a reaction product of a compound and an aluminum halokene compound, and (b) an organoaluminum compound, and these catalyst threads are used to polymerize the catalyst under the polymerization conditions described below. A polymer having a significantly high polymerization amount and excellent rigidity and moldability can be obtained, and other catalysts such as titanium trichloride-alkylaluminum system and titanium tetrachloride-trialkoxyvanadyl-alkylaluminum system can be used. It is also advantageous to use manufactured polyolefins.

To explain the catalyst used, the oxygen-containing organic compound of magnesium used in preparing the reaction product of (a) is ng(oR')mx;-□ (wherein R' is an alkyl group , represents an aryl group or a cycloalkyl group, XI represents a halogen atom, and m represents/), such as magnesium jetoxide, magnesium dimethoxide, magnesium diphenoxide, magnesium monoethoxy chloride, magnesium monophenoxy Examples include chloride, magnesium monoethoxypromide, and magnesium monoethoxypromide. Among these, magnesium jetoxide is preferred. As a titanium halogen compound, the general formula TiX
%(OR''-n (wherein, X2 represents a halogen atom)
HR represents an alkyl group, an aryl group, or a 7-chloroalkyl group, and n represents the number of t-j), such as tetrahalogenated titanium tetrachloride, titanium tetrabromide, titanium tetraiodide, etc. Titanium, monoethoxytrichlortitanium,
Examples include monomethoxytribromotitanium and jetoxydichlorotitanium. Among these, titanium tetrahalide is preferred. The reaction between the oxygen-containing organic compound of magnesium and the tetanogen compound is carried out by bringing the two into contact at a temperature of 5°C or 2°C in the presence or absence of an inert hydrocarbon solvent. The reaction product is obtained as a precipitate, and unreacted substances are washed away with an inert hydrocarbon solvent. There is no particular limit to the atomic ratio of titanium to magnesium in the reaction ratio between the two, but if it is too large, titanium will be wasted, and if it is too small, the polymerization activity will decrease. Therefore, usually Ti
/Mg=0. It is preferable to set it as /~100 molar ratio.

Next, examples of the magnesium oxygen-containing organic compound used in preparing the reaction product of (a) include the magnesium compounds of the general formula shown above. The oxygen-containing organic compound of titanium has the general formula T i (OR”)
kX, "-k (in the formula, R3 represents an alkyl group, aryl group or cycloalkyl group, Xl represents a halogen atom, and k represents the number of l-da), for example, tetraethoxy7 titanium , tetra-n-propoxy titanium, tetra-n-butoxy titanium, tetraphenoquititanium, triethoxymonochlor titanium, tri-n-butoxy monochloro titanium, jetoxydichlor titanium, tri-n-butoximotuprom titanium, etc. Among these, k is 3 or Hiro's compounds are preferred.As the aluminum halogen compounds, compounds with the general formula htR',
,X',-,.

(In the formula, 14 represents an alkyl, aryl, or cycloalkyl group, and Xl represents a halogen atom. p is O<p<3
examples thereof include ethylaluminum dichloride, normal propylaluminum dichloride, ethylaluminum sesquichloride, diethylaluminum monochloride, etc. Among these, a compound in which chlorine is used and p is 7 is preferred.

The reaction between an oxygen-containing organic compound of 1gnesium, an oxygen-containing organic compound of titanium, and an aluminum halide compound is
First, an oxygen-containing organic compound of magnesium and an oxygen-containing organic compound of titanium are mixed and heated to 100C-/60C to prepare a uniform liquid. If it is difficult to produce a uniform liquid, it is preferable to include alcohol.

Examples of the alcohol include ethyl alcohol, n-butyl alcohol, and n-octyl alcohol. An inert hydrocarbon solvent is then added to form an inert hydrocarbon solution. An aluminum halogen compound was added to the inert hydrocarbon solution obtained as above, and the mixture was heated at room temperature to 100C.
When the reaction is carried out, the reaction product is obtained as a precipitate, and unreacted substances are washed away with an inert hydrocarbon solvent. The quantitative ratio of each component is the atomic ratio of titanium to magnesium (Ti/
Mg), the ratio of the sum of grams of all halogens to the sum of Durham equivalents of magnesium and titanium is preferably 0.1 to 10°, Mg+Ti, /, O-coO.

Note that the total halogen herein refers to the halogen contained in the oxygen-containing organic compound of magnesium, the oxygen-containing organic compound of titanium, and the aluminum halogen compound.

On the other hand, the organoaluminum compound used as a cocatalyst has the general formula AtR:
(l represents a halogen atom, q represents a number from 7 to 3), such as triethylaluminum, tri-n-propyl aluminum, tri-n-butyl aluminum, triisobutyl aluminum, diethylaluminium monochloride, di-n-furopyl Aluminum monochloride etc. are excluded.

Among these, diethylaluminum monochloride or a mixture of diethylaluminum monochloride and triethylaluminum is particularly preferably used.

In the present invention, homopolymerization of ethylene is carried out in a hydrocarbon solvent at a temperature of 3θG-100C using the above catalyst system. Examples of hydrocarbon solvents include inert hydrocarbon solvents such as aliphatic hydrocarbons such as hexane and heptane, aromatic hydrocarbons such as benzene, toluene, and xylene, and alicyclic hydrocarbons such as cyclohexane and methylcyclohexane. It will be done.

Therefore, in the present invention, the polymerization reaction is carried out as described in (a) below.
, (b), carried out under the East subject of e9.

(b) The polymerization reaction is carried out in one step, that is, the reaction mixture obtained by polymerization in the first reaction zone is further polymerized in the second reaction zone. (b) Either of the first and first reaction zones In one zone, the molar ratio to ethylene in the gas phase is 0.07
~/, in the presence of 0 hydrogen, the viscosity average molecule jklO
30,000 to 700,000 polymer A, 30% by weight of the total polymer production value
~70% by weight was produced, and in the other zone, polymerization was performed in the presence of hydrogen at a molar ratio of /, 0-/j to ethylene in the gas phase to produce a polymer B with a viscosity average molecular weight of 10,000 to 10,000 g. 70% by weight to 3θ weight% of the total polymer production amount,
Further, (viscosity average molecular weight of polymer A)/(viscosity average molecular weight of polymer B) is set to 10 to 4 tO (c) 1st. Both the first reaction zone and ethylene are used for homopolymerization, and d) the melt index of all the polymers finally produced is 0. / -1, O1710 minutes.

These three conditions (a), (b), (c), and (ii) will be explained. The one-step polymerization (a) can be carried out by either a continuous polymerization method or a batch polymerization method.

In the case of continuous polymerization, the reactors are arranged in series, and the reaction mixture obtained by polymerization in the first reactor is introduced into the first reactor to continue the polymerization.

And, if necessary, a flash cypress capable of purging most of the hydrogen is installed between the co-group reactors. In the case of batch polymerization, the reactions are carried out sequentially in one reactor. Of these, continuous weight□
preferably.

According to the reaction and matter (b), first, in either the first or first reaction zone, the molar ratio to ethylene in the gas phase is o, oi ~/, 0°, preferably 0.
Polymerization is carried out in the presence of hydrogen of 03 to Oj to produce 30% to 10% by weight of polymer A of the total amount of the final polymer produced, but the viscosity of the resulting polymer A is The average molecular weight is /Q from 70,000 to 700,000. What is the viscosity average molecular weight?

/ Measure the intrinsic viscosity in the JOC tetralin solution, [η
]=Da, 6θX/f'X'M'・721 C(
η] is the intrinsic viscosity, and M is the value calculated from the formula (viscosity average molecular weight). When polymer A is produced in the second reaction zone in the presence of polymer B produced in the seventh reaction zone, the viscosity average molecular weight of polymer A is expressed by the following formula: [η)A = (10(7(η)-WB(η)B,)/WA
(In the formula, [η] indicates the intrinsic viscosity of polymer A, and [η]
3 indicates the limiting viscosity of polymer B, [η] indicates the limiting viscosity of the entire polymer finally obtained in the first reaction zone, and wA
indicates the weight percent of polymer A produced in the first reaction zone,
The viscosity average molecular weight can be calculated from [η]A (WB indicates the weight percent of the polymer B produced in the first reaction zone).

However, if the viscosity average molecular weight is less than 100,000, the impact strength of the resulting polymer (the total polymer finally produced)
Tear strength and environmental cracking resistance become low, and if it exceeds 700,000, formability becomes low, which is not preferable. The preferred range is /S 10,000 to jθ 0,000, particularly preferably λO 0,000 to Da 00,000. When the molar ratio of hydrogen to ethylene in the gas phase is less than o, oi, the viscosity average molecular weight often exceeds 0,000,
If it exceeds 17, the viscosity average molecular weight will often be less than 10,000, which is not preferable. If the amount of 3ONf produced is less than 1%, the impact strength, tear strength, and environmental cracking resistance of the resulting polymer (finally produced polymer) will be low, and if it exceeds 10 times ik-, the moldability will be low, which is undesirable. . The preferred range is 3
0% to 10% by weight, especially 33% by weight! Weight -
It is.

The polymerization reaction is performed at soC ~ 1007: 10 minutes ~ IO
Time, o, sky/a/i gauge~/00 kg/c
It may be carried out under a pressure of r/1 gauge.

Then, in the other reaction zone, the molar ratio to ethylene in the gas phase is 1. θ~/! , preferably in the presence of /j-1 hydrogen to give a viscosity average molecule f1i: /10,000~
JO polymer B is produced in an amount of 70% by weight of the total amount of the final polymer produced. The viscosity average molecular weight can be determined by measuring the limiting viscosity in a /30C tetralin solution and calculating from the front foot formula. When polymer B is produced in the first reaction zone in the presence of polymer A produced in the first reaction zone, the viscosity average molecular weight of polymer B is expressed by the following formula 1 formula %) (formula In the middle, [η] indicates the intrinsic viscosity of polymer B, and (W:
) a represents the intrinsic viscosity of polymer A, [da] represents the intrinsic viscosity of the entire final product obtained in the first reaction zone,
W- indicates the weight % of polymer A obtained in the first reaction zone, W'B#'i indicates the weight % of polymer B obtained in the first reaction zone). It is a good idea to calculate the viscosity average molecular weight.

However, if the viscosity average molecular weight is less than 7, the impact strength of the resulting polymer (all the polymers finally produced) will decrease, and if it exceeds 10,000, the moldability will decrease, which is not preferable. If the molar ratio of hydrogen to ethylene in the gas phase is less than /, 0, the viscosity average molecular weight of the polymer B will often exceed 10,000 yen, and if it exceeds 13, it will often be less than 1 formula, which is not preferable. The preferred range is 10,000 to Jj million. If the production amount exceeds 70% by weight, the impact strength, tear strength, and environmental cracking resistance of the resulting polymer (finally produced polymer) will be low, and if it is less than Jon wave, the moldability will be low. No/The preferred range is 70% by weight to qo% by weight, especially i
T heavy-I! c%~da! This is Shigekei.

The polymerization reaction was carried out at 50C~/θOC, l.

Minutes ~ IO time, a,! ;kg/cr/L gauge~/0
It may be carried out under a pressure of 0 kglcr & gauge.

Regarding the order of polymerization, polymer A may be produced and then polymer B may be produced, or polymer B may be produced first and then polymer A may be produced.

(Viscosity average molecule i of polymer A)/lf viscosity average molecule 1t- of coalesce B) is lθ~qo. If this ratio is less than 70, moldability decreases, and if it exceeds 0, impact strength decreases, which is not preferable.

Therefore, according to the conditions of (2), the melt index of the entire polymer finally produced, that is, the mixture of polymer A and polymer B, is set to f O0/~/, 09/10 minutes. Here, the melt index is based on JISK 60, /deO
C%λ, value measured under 16# load, unit is 9710
It's a minute. If the melt index exceeds 00%, the impact strength of the entire polymer finally produced will decrease, which is not preferable. If the melt index is less than O1l, moldability and surface roughness under high shear will be poor, making it unsuitable for polyethylene for high-speed blow molding, which is the object of the present invention.

The density of the polymer produced as above is 6S
~0.97 daf/aa, and the molded product has extremely high rigidity. Furthermore, the polymer thus obtained is easy to stretch uniformly, and it is difficult to blow out even when air is blown at high speed during blow molding.

Furthermore, there is no roughening of the skin under high shear. The polymer obtained by the present invention is easily homogenized and can be sufficiently homogenized even by continuous kneading using a single-screw extruder.

The fish eye Fi of the obtained molded product is extremely low.

Polymers having the above characteristics are suitably used as resource-saving and energy-saving polyethylene for high-speed thin-wall blow molding, and as high-rigidity polyethylene for blow molding where strength is important.

For example, it is suitable for use in milk bottles, drinking water bottles, food bottles, medicine bottles, toys, oil cans, and the like.

Next, the present invention will be explained in detail with reference to Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded.

In addition, in the following examples, physical property tests were conducted using the obtained polymer powder f 20 rrmφ extruder (resin temperature 260C+
The measurement was performed using a sample that was kneaded at 10C) and made into a pellet.

Melt index (ur): JIS K btbθ
Flow Prevalence Ratio (PR): In an ASTM D-/2JgK abrasive melt index device, the shear stress values io” ayne /ctit and i ollayn
Outflow ratio at e/all (MI 106/M/
θ') Density (P/ca): JIS K/,
Ri60 stainness (decay/m): ABTM D Riq
7"1111 (5ee-') (Starting of rough skin!)
blJIIr speed [): Direct extrusion blow molding machine (S
#J fat was extruded at a temperature of /90C from a straight die (length J diameter) of a die (O.W. The shear rate at which the rough skin of Pa9son begins was defined as rSIN (81110-1).

High-speed thin-wall molding test: Varying the diameter and wall thickness of the parison, molding temperature /90C,
J- under molding conditions of blow pressure A A1i/ crlt G
A round bottle of o o oa was formed into a thin wall at high speed, and its formability was examined (bottle weight l!~, yot) If good high speed thin wall performance was shown, it was indicated as good, and if it was poor, the condition was indicated. Show.

Measurement of buckling strength: The strength at the first buckling was measured when a 50θOC round bottle (empty bottle, without cap) with the maximum bottle weight was compressed at a compression speed of /Omn 7 minutes.

Example-1 (4) Preparation of catalyst components Magnesium jetoxide//31 and tri-n-butoxymonochlorotitanium/! 01 and n-butanol, ? 7F
and were mixed at /307 for t hours to homogenize. Then A
The temperature was lowered to OC, and benzene J and 7 jtf were added to form a homogeneous solution. Then add ethylaluminum sesquichloride +&? F was added dropwise, and stirring was continued for 1 hour with AOC. A brown catalyst component 2099 was obtained by washing the generated precipitate with n-hexane. Dry a portion of the solid obtained.

It was made into powder. My in this powder is 10. /wt%, T
It contained 9.8% by weight of 1.

(B) In an autoclave with ethylene polymerization content xtot, normal hexane r
, o t, catalyst component 100111 obtained in the above (A)
I prepared 9. In addition, diethylaluminum monochloride (DF!A)/j mmot was charged into another feeder and the autoclave was equipped. After raising the internal temperature of the autoclave to 90C, a predetermined amount of H1 was introduced, and then ethylene and diethylaluminum monochloride were supplied from a separate feeder to start polymerization. The polymerization reaction is continued for t time while supplying ethylene intermittently so that the total pressure remains constant.
,Oo.

Met.

Next, after purging unreacted monomers, the autoclave internal temperature was brought to gSC, and predetermined amounts of hydrogen and ethylene were newly introduced to restart polymerization. After continuing the polymerization reaction for 90 minutes while supplying ethylene intermittently to keep the total pressure constant, unreacted monomers were purged. The average gas phase composition [H,/PT7)G during this first stage polymerization reaction was djmot%, the MI of the obtained polymer was 0.769710 min, FR = 70, and the density was 0.949 J f It was 10c. Table 1 shows the results of measuring the physical properties of the obtained polymer. In addition to having high rigidity, the shear rate at which rough skin begins to appear is also high, indicating high rigidity and good high-speed thin-wall formability.

(C) High-speed thin-wall molding test Using the polyethylene obtained in the above (B), high-speed thin-wall molding was attempted under the above molding conditions with the parison diameter and wall thickness changed as shown in Table 1.

The results are summarized in Table 1. Under the parison thickness condition, roughness was observed on a part of the parison surface and blow-out occurred, but under other conditions, good high-speed thinning properties were exhibited.

Examples K to J Ethylene polymerization was carried out in the same manner as in Example 1 (B) except that the catalyst obtained in Example 1 (4) was used and the polymerization conditions were changed as shown in Table 7. I did this.

The results are shown in Table/.

In addition, in high-speed thin-wall molding tests, the parison exhibited good thin-wall moldability, with no signs of surface roughness.

One-stage polymerization of ethylene was carried out under the polymerization conditions shown in Table 1 using the catalyst obtained in (A) of Comparative Example-Example-/.

The results are shown in Table 1. On a single-stage heavy platform, low density and weak rigidity cannot be obtained even with the same Ml. In addition, a high-speed thin-wall molding test was conducted using polyethylene obtained in the same manner, but the surface roughness occurred in the low shear rate region, making it unsuitable for high-speed molding.

Comparative Example - (A) Preparation of Catalyst Component Commercially available fine powder silica was impregnated with an aqueous chromium trioxide solution, dried at θC and activated in dry air at θC to prepare a catalyst containing chromium, o, zx, and s. One component was prepared. Hexane/1. The above catalyst first component A, Of, and triethylaluminum 64IRQ were charged, and after heating up to C, H and gas were injected so that the hydrogen pressure became θ,'lkf/d. Then, ethylene gas was introduced, and 30 f of ethylene was polymerized in a total of 90 minutes. Upon completion of the reaction, the product was washed several times with hexane by decantation (catalyst-polyethylene mixture).

(B) Polymerization: 10 μM of the catalyst-polyethylene mixture obtained in (a) above was added to the crepe.

■, Diethyl aluminum monoethoxide J g,! i
■, hexane, 11 were charged, and the gas phase inside the reactor was heated at 90C (
H, / ICT7) The composition is /! 1 cup was carried out for 1.3 hours at r Omo 1% and total pressure 1 kg/cyst-a,
Polyethylene/0 kg# was obtained.

The melt index (MI) of the produced polyethylene is O
o,2,PR=730. The density (ρ) Fio was 96λ.

(C) High-speed thin-wall molding test example-/Similarly to (C), high-speed thin-wall molding was attempted and the results were summarized. Although this is one of the typical blow grades, surface roughness occurred in the high shear rate region, and blow-out occurred in thin-wall molding at high blow ratios. Also, the value of 7'C is lower than that of Examples 7 to 3.

Comparative Example-3 Using the catalyst component obtained in Example-/(A), 1-butene copolymerization was performed. That is, normal hexane lθo was placed in an autoclave with an internal capacity of 2 tons.

-, a catalyst component of 20η was charged. In addition, 3-mmoz of diethylaluminum monochloride was charged into a separate feeder, which was then installed in the autoclave. After raising the internal temperature of the autoclave to 90 cmf, a predetermined amount of H2 was introduced, and then ethylene and diethylaluminum monochloride were supplied from the S/feeder to initiate polymerization. The polymerization reaction was continued for 1 hour while supplying ethylene intermittently to keep the total pressure constant. Average gas phase composition during this period (He/
ETy) G Fij J Ornot%.

Next, after purging unreacted monomers, the temperature inside the autoclave was raised to 17C, and a predetermined amount of hydrogen and the copolymerization monomers /-butene and ethylene were supplied to restart the polymerization.The total pressure was kept constant. After continuing the polymerization reaction for 90 minutes while supplying ethylene intermittently, unreacted monomers were purged.The average gas phase composition during this second stage polymerization reaction was CHt/KT7)G was Jk mot%, [Butene/I! iT7]G was ko, komot%. Moreover, Ml of the obtained polymer is 0.3t/10min, PR=
4/, density is 0.91! It was f/ac.

As a result of measuring the physical properties of the obtained polymer, the rigidity was low in proportion to the density, and the stiffness of the pressed piece was //, 000/
d, the bottle buckling strength was low.

Procedural amendment (spontaneous) 1/2/2019 Title of the invention Process for producing polyethylene with high rigidity and suitable for high-speed blow molding 3 Person making the amendment Applicant Mitsubishi Chemical Industries, Ltd. 4 Agent 〒100 5 Subject of amendment Contents of amendment in column 6 of detailed explanation of the invention in the description

Claims (1)

[Claims] (1) (a) A reaction product between an oxygen-containing organic compound of magnesium and a titanium halide compound, or a reaction product between an oxygen-containing organic compound of magnesium, an oxygen-containing organic compound of titanium, and an aluminum halide compound;
)) When carrying out the homopolymerization of ethylene at a temperature of 30 to 100 C in a hydrocarbon solvent using a catalyst system consisting of an organoaluminum compound, (a) the polymerization reaction is carried out in one step, that is, in the first reaction zone; (b) The reaction mixture obtained in this manner is further polymerized in the first reaction zone, and (b) the molar ratio to ethylene in the gas phase is 0. 0
Polymer A with a viscosity average molecular weight of 10,000 to 0,000 is obtained by polymerizing in the presence of hydrogen of / -/, 0, and the total amount of polymer produced is aO to 7.
0% by weight and in the other zone a molar ratio of 1.0% to ethylene in the gas phase. Polymer B with a viscosity average molecular weight of 10,000 to 20,000 is produced in the presence of O to 13 hydrogen, and the viscosity average molecular weight of Polymer A/ The viscosity average molecular weight of polymer B is 10-daO
Further, 1 (c) Both the 1st and 1% first reaction zones are ethylene homopolymerized, and 2) The melt index of the entire polymer finally produced is 0.1 to /f/10 min, and the density is 0. 9 & ~ 0.97
A method for producing polyethylene that is characterized by having a high rigidity and is suitable for high-speed polyethylene molding.