JPH0714981B2 - Method for producing ethylene-α-olefin copolymer - Google Patents

Description

TECHNICAL FIELD The present invention relates to an ethylene-α-olefin-based copolymer,
More specifically, it relates to a method for efficiently producing an ethylene-α-olefin-based copolymer having excellent transparency, flexibility and mechanical strength, which is composed of ethylene and a chain olefin having 3 to 10 carbon atoms.

(Prior Art) An olefin polymer is used alone or in a mixture with another polymer to form a film, a tape, a sheet, a hollow molded article, an injection molded article, or the like, and is used in many fields.

Many proposals have hitherto been made on a method for producing a copolymer having low crystallinity, which is composed of ethylene and α-olefin. For example, in Japanese Examined Patent Publication No. Sho 46-21212, 40-110 ° C
Is disclosed for producing a copolymer of ethylene and an α-olefin using a catalyst composed of a vanadium compound and an organoaluminum halide at the temperature of. However, according to this method, the produced ethylene-α-olefin-based copolymer is dissolved in the polymerization solvent and can be produced as a uniform solution, but the vanadium compound used in this method becomes higher as the polymerization temperature increases. Polymerization activity is significantly reduced, and in the temperature range of 40 to 110 ° C. disclosed in the publication, only a very disadvantageous polymerization activity is practically obtained, and the molecular weight distribution of the obtained polymer (generally Mw / Mn Shown)
However, only an ethylene-α-olefin copolymer having a wide surface area, a large surface tackiness and a large surface stickiness can be obtained.

Further, Japanese Patent Publication No. 47185/1987 discloses a soft olefin using a catalyst system in which a halogenated lower aliphatic hydrocarbon or a hydrocarbon having 3 to 5 carbon atoms is used as a reaction medium and a VOX ₃ compound and an organoaluminum compound are combined. A method of making a copolymer is disclosed. In the polymerization method in this halogenated lower aliphatic hydrocarbon, the produced polymer precipitates as an insoluble component and produces a mixture of the produced polymer and the polymerization medium (hereinafter referred to as slurry). However, when halogenated lower aliphatic hydrocarbons are used, there is a problem in terms of corrosion and storage stability of the equipment due to halogens generated by decomposition. Further, in the case of slurry polymerization in a hydrocarbon medium having 3 to 5 carbon atoms, this medium has a boiling point close to that of an α-olefin copolymerized with ethylene, particularly propylene or 1-butene, so that the unreacted monomer is not reacted. Separation of the monomer and the polymerization solvent becomes a big problem in the purification process. Moreover, since the polymer particles produced are hard, the detouching step of removing the catalyst component taken in by the polymer particles is also difficult.

Further, JP-B-55-24447 discloses that an aliphatic hydrocarbon having 6 to 15 carbon atoms is used as a polymerization solvent from ethylene and 1-butene, and a vanadium compound which can be used as a polymerization catalyst and a molar ratio of an aluminum atom to a vanadium atom are used. 2 to
Using a catalyst consisting of 50 organoaluminum halides,
A method for producing a copolymer having an ethylene content of 85 to 95 mol% is disclosed. However, the method of using an organoaluminum halide having such an atomic molar ratio and a soluble vanadium compound as a catalyst has drawbacks such as low polymer yield per unit vanadium and low tensile strength.

(Problems to be Solved by the Invention) The object of the present invention is to eliminate the above-mentioned drawbacks of the prior art, have high polymerization activity, and facilitate the steps of separation, purification, stirring, and transfer of the production process, and It is an object of the present invention to provide a method for producing a low-crystallinity ethylene-α-olefin-based copolymer which has a simple detouching step, is excellent in transparency, flexibility and mechanical strength, and has no surface stickiness.

(Means for Solving Problems) The present inventors achieved the above-mentioned object by copolymerizing a specific monomer under a specific catalyst, a specific polymerization medium and specific polymerization conditions. The inventors have reached the present invention by finding that.

In producing an ethylene-α-olefin copolymer from ethylene and a chain α-olefin having 3 to 10 carbon atoms, the present invention uses a soluble vanadium compound as a polymerization catalyst and a general formula RnAlCl ₃ -n (wherein n is a number of 1.8 to 0.8, R is an alkyl residue having 2 to 6 carbon atoms), and a catalyst comprising an organic chlorinated aluminum compound represented by the formula (1) and the soluble vanadium compound (V) and the organic compound are used. Composition ratio Al / V (molar ratio) with chlorinated aluminum compound (Al) is 55 ~
170, using n-hexane, n-heptane or cyclohexane as a polymerization catalyst, and a polymerization temperature of + 30 ° C to -20
The ethylene content is 75 to 90% by weight and the ratio Mw / Mn of the weight average molecular weight (Mw) to the number average molecular weight (Mn) obtained by slurry-polymerizing the ethylene and the α-olphin at 2 ° C is 2
~ 5, melting point (Tm) determined by differential scanning calorimeter (DSC)
Is an ethylene-α-olefin copolymer having a temperature of 40 to 90 ° C.

In the present invention, ethylene and a chain α-olefin having 3 to 10 carbon atoms are used as the copolymer component.

Examples of the chain α-olefin having 3 to 10 carbon atoms include propylene, 1-butene, 1-pentene, 1-hexene,
1-octene, 1-decene, 4-methyl-1-pentene and the like are used alone or in combination, preferably propylene, 1-butene or 1-hexene, particularly preferably 1
-Butene is used.

The polymerization catalyst used in the present invention comprises a soluble vanadium compound soluble in a polymerization solvent described below and a general formula RnAlCl ₃ -n (wherein n is a number of 1.8 to 0.8 and R is an alkyl residue having 2 to 6 carbon atoms). (Means) and an organochlorinated aluminum compound represented by the formula (1).

Soluble vanadium compounds include vanadium oxyhalide compounds, vanadium tetrahalides, VO (OR ')
₃ (R 'means an alkyl residue), which is a reaction product of vanadium oxytrichloride and alcohol, VO (OR ") mCl3 _- m (-OR" is an alcohol residue, 3>m> 0), a mixture of a vanadium oxyhalide compound and a vanadate compound,
Vanadium triacylacetonate, oxyvanadium acetylacetonate, etc. are used, and examples thereof include vanadium oxytrichloride, ethyl vanadate, n-propyl vanadate, n-butyl vanadate, 2-ethylhexyl vanadate, vanadium oxytrichloride and n. Reaction products with alcohols (wherein n-alcohol is ethyl alcohol, propyl alcohol, n-butyl alcohol,
2-ethylhexyl alcohol and the like) are used.

Examples of the organic chlorinated aluminum compound represented by the general formula RnAlCl ₃ -n include aluminum compounds such as aluminum sesquichloride, ethyl aluminum dichloride, isobutyl aluminum sesquichloride and isobutyl aluminum dichloride. It is also possible to use these aluminum compounds as a mixture with diethylaluminum or the like in advance, or simultaneously add them at the time of polymerization.

In the present invention, the composition ratio Al / V (atomic mole ratio) of the soluble vanadium compound (V) and the organic chlorinated aluminum compound (Al) is 55 to 170, preferably 60 to 150. This Al / V
Is less than 55, it is necessary to increase the amount of the vanadium compound in order to obtain a high polymerization activity, the vanadium metal in the finally obtained ethylene-α-olein-based copolymer such as oxides. A large amount remains in the form, and as a result, problems such as deterioration of the hue of the final product occur, and the resulting copolymer has a wide molecular weight distribution and increased stickiness, resulting in problems such as low hardness. On the other hand, when Al / V exceeds 170, α-
The copolymerizability of olefins decreases, the ethylene content increases, and the transparency and flexibility decrease. It is speculated that when the amount of Al is extremely large relative to V, the reduction of the vanadium compound proceeds too much and the polymerization active species change from a preferable state.

The polymerization catalyst of the present invention includes, for example, activity improvers such as polyhalogen compounds such as trichloroacetic acid ester and 2,3,4,4-tetrachlorobutenoic acid ester, electron donors such as alcohols, ketones and amines. Can also be used by premixing with the soluble vanadium compound or the organoaluminum chlorinated compound or added simultaneously.

The polymerization solvent used in the present invention is n-hexane, n-heptane or cyclohexane.

In the method of the present invention, the polymerization temperature for slurry polymerization is +
The temperature is 30 ° C to -20 ° C. In this temperature range, most of the ethylene-α-olefin-based copolymer of the present invention is not dissolved in the polymerization solvent and is obtained as a swollen precipitate in the polymerization solvent, and as a result, the product is in a slurry state. In addition, the viscosity of the reaction product is low, stirring and transfer are easy, it is economical, and the detouching process can be performed easily. Further, the polymerization catalyst exhibits a very high polymerization activity in the temperature range of + 30 ° C to -20 ° C. It is possible to lower the polymerization temperature, but it is not preferable because cooling energy is required.

The ethylene content in the ethylene-α-olefin-based copolymer produced according to the present invention has no surface stickiness,
From the viewpoints of good transparency, flexibility and mechanical strength, it is 75 to 90% by weight, preferably 77 to 88% by weight.
When the ethylene content exceeds 90% by weight, the hardness of the copolymer becomes too high, and the flexibility of the molded product decreases. In addition, cold resistance is also deteriorated. If it is less than 75% by weight, the mechanical strength such as tensile strength is lowered, and the surface of the molded article becomes sticky.
It is not a target of the copolymers of the present invention. The ratio Mw / Mn of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the obtained copolymer is 2 to 5 from the viewpoint of reducing the stickiness of the surface of the molded product, and Mw / Mn is Molded products using copolymers exceeding 5 have surface stickiness, while Mw / Mn
It is difficult to obtain a copolymer having a ratio of less than 2 under the conditions of the present invention. Furthermore, the melting point (maximum value of endothermic peak in endothermic pattern based on melting point (Tm) of ethylene copolymer) determined by a differential scanning calorimeter (hereinafter referred to as DSC) is 40 to 90 ° C, preferably 60 to 85 ° C. . If it is less than 40 ° C, the mechanical strength such as tensile strength is low, and if it exceeds 90 ° C, it is inferior in flexibility and is out of the scope of the present invention. Further, it is preferable that there is no or very little endothermic peak due to the ethylene long chain at around 120 ° C. This indicates that the ethylene and the α-olefin are randomly bonded during the copolymerization, whereby a copolymer having good cold resistance and impact resistance can be obtained.

In the present invention, the specific ethylene copolymer monomer is subjected to the copolymerization reaction under the specific catalyst medium and the conditions as described above, and thus the transparency, the cold resistance and the impact resistance are excellent, and the surface is solid. An ethylene-α-olefin-based copolymer without sticking is obtained.

Explaining the production method of the present invention in addition to the specific conditions, it may be either a polymerization batch system or a continuous system, and the reactor may be a single reactor or a plurality of reactors connected in series or in parallel, and raw olefins may be used separately or It is introduced by mixing in advance. The reaction temperature is maintained by an external cooling method, or by utilizing latent heat of vaporization of a solvent or a monomer. The pressure can be in a wide range from a depressurized state (100 mmHg) to a pressurized state (about 50 atm). The molecular weight can be controlled by the composition ratio of the catalyst, the amount of the catalyst, the catalyst species, the polymerization temperature, and the like, and the molecular weight controlling agent such as hydrogen can be used. Separation of the produced copolymer from the reaction medium and unreacted monomers, termination of catalyst activity, removal of catalyst residue and drying of the copolymer, molding such as granulation are carried out by conventional methods.

The ethylene-α-olefin copolymer obtained by the present invention is modified by another olefin polymer resin, an olefin copolymer resin, an olefin copolymer rubber, a graft of a carboxylic acid, etc., alone or according to the purpose. Olefin (co) polymers, etc., and optionally organic or inorganic fillers, reinforcing agents such as fibers, etc., and processed by means such as mixing, laminating, etc. to form films, tapes, sheets, hollow molded articles, Used as an injection molded product.

(Effect of the invention) According to the present invention, a specific monomer is subjected to a copolymerization reaction under a specific catalyst, a polymerization medium and polymerization conditions,
It is possible to obtain an ethylene-α-olefin-based copolymer which is excellent in transparency, flexibility and mechanical strength and has no surface stickiness. In addition, the steps of producing the polymer of the present invention are excellent in that the steps of separation, purification, stirring, and transfer are easy, and the detouching step is simple.

(Examples) Hereinafter, the present invention will be described in detail with reference to Examples.

The analysis method for identifying the ethylene-α-olefin-based copolymer obtained in the following examples is as follows.

(Ethylene content) Ethylene-α-olefin copolymer ¹ H-NMR
And ¹³ C-NMR were used to determine the ethylene / α-olefin composition ratio, and a calibration curve was prepared by infrared analysis. The composition of the copolymer was determined based on this calibration curve.

(Mw / Mn) According to Takeuchi's "Gel Permeation Carmatograph" (published by Maruzen Co., Ltd.), the measurement was performed as follows.

(1) A standard polystyrene having a known molecular weight (manufactured by Toyo Soda Co., Ltd., monodisperse polystyrene) is used to obtain a molecular weight M.
And its GPC (Gel Permeation Chromatograph) count are measured, and a correlation curve calibration curve of molecular weight M and EV (Elution Volume) is drawn. The concentration at this time is 0.02% by weight. The calibration curve of standard polystyrene is corrected to the calibration curve of ethylene-α-olefin copolymer by the universal method.

(2) The GPC pattern of the sample is obtained by the GPC measurement method, and M is obtained by the above (1). At this time, sample preparation conditions and GPC measurement conditions are as follows.

(Sample preparation conditions) (a) 2,6 as an anti-aging agent in o-dichlorobenzene
-Di-t-butyl-p-cresol 0.08% is added and dissolved.

(B) The sample is dispensed into an Erlenmeyer flask together with the o-dichlorobenzene solution of (a) so that the sample becomes 0.1%.

(C) The Erlenmeyer flask of (b) is heated to 120 ° C. and stirred for about 60 minutes to dissolve it.

(D) The solution of (c) is applied to GPC and automatically in the GPC device.
Filter through a 0.5 μm sintered filter.

(GPC measurement conditions) (a) Apparatus: Waters 150C type (b) Column: Toyo Soda Co., Ltd. H type (c) Sample amount: 500μ (d) Temperature: 120 ° C (e) Flow rate: 1 ml / min (F) Total number of theoretical plates: 1 × 10 ⁴ to 2 × 10 ⁴ (measured value by acetone) (melting point by DSC) The differential scanning calorimeter (DSC) is a DuPont 910 type Defe.
The rrential scanning calolimeter was used, and the recorder used was a DuPont 990 type Thermal Analyzer. The sample amount was 10 ± 0.1 mg, and α-alumina (Shimadzu Corporation DSC standard sample) 10.1 mg was used as a reference. To measure, first load the sample and Reference to the DSC at room temperature,
Heat to + 180 ° C, then cool to -100 ° C at a constant rate of 10 ° C for 1 minute. Then, analysis is performed at a temperature rising rate of 20 ° C. for 1 minute. The typical DSC pattern obtained is shown in FIG. The melting point (Tm) determined by the present invention is the maximum value of the endothermic peak shown at point P in FIG.

(Evaluation Method of Other Physical Properties) (1) Tensile Strength and Tensile Elongation: Molded sheets were measured according to JIS K6301.

(2) Surface Stickiness of Molded Product: The molded sheet of (1) was evaluated by the following from the feel of a surface machine.

Stickiness is not felt at all: ◎ Stickiness is barely felt: ○ Stickiness is slightly felt: △ Stickiness is apparent: × (3) Transparency (1) Molded sheet Each example and comparison The samples of the examples were compared and evaluated by the following.

Very excellent transparency: ◎ Good transparency: ○ Poor transparency: × (4) Flexibility: The molded sheet of (1) was bent with both hands and evaluated by the following.

Excellent flexibility: ◎ Relatively excellent flexibility: ○ Inferior flexibility: × Example 1 Polymerization reaction was carried out by batch reaction using a 3 stainless steel polymerization device equipped with a stirring blade and a jacket cooling device. First, n-hexane 1.5 was charged as a polymerization solvent into a polymerization vessel which was sufficiently replaced with N ₂ gas, and then 1-butene 4
00g was injected. Add ethylene gas to this with a gauge pressure of 6 kg / c
It was blown in until it reached m ² , and hydrogen was further blown in to make it 10 kg / cm ² . Temperature-controlled water was passed through this jacket to adjust the temperature to 20 ° C.

Then, 24 mmol of Al-atom n-hexane solution of ethylaluminum sesquichloride (hereinafter referred to as "EASC") was pressure-inserted into a catalyst charging container attached to the polymerization vessel, and stirring was started. Further, an n-hexane solution of a mixed reaction mixture of vanadium oxytrichloride (hereinafter referred to as VOCl ₃ ) and n-butyl alcohol (hereinafter referred to as n-BuOH) in a ratio of 1: 3 (molar ratio), which was placed in a similar catalyst charging container. 0.4 mmol in V atom
After press-fitting the vanadium compound, continue the reaction for 5 minutes,
After 5 minutes, open the valve attached to the top of the polymerization reactor,
The pressurized monomer gas was removed, and about 10 ml of methyl alcohol in which a small amount of antioxidant was dissolved was added. Steam was blown into the obtained reaction product to remove the solvent and unreacted monomer, and the produced polymer was dried using a hot roll at 110 ° C.

Table 1 shows the polymerization conditions, the polymerization results, the analysis results of the resulting copolymer, and the physical properties.

Comparative Example 1 EASC was set to 16 mmol, ethylene injection pressure was 6.5 kg / cm ² ,
Copolymer was obtained by treating with hydrogen gas to 10.5 kg / cm ² and otherwise treating in the same manner as in Example 1, and the results are shown in Table 1.

From the comparison between Example 1 and Comparative Example 1, when Al / V is smaller than the requirement of the present invention, the polymer yield per unit vanadium metal is lowered, the tensile strength is also lowered, and the surface solid of the molded product is reduced. It can be seen that the stickiness is slightly inferior.

Example 2 EA using VOCl ₃ 0.2 mmol as a soluble vanadium compound
The SC was adjusted to 26 mmol, the introduction pressure of ethylene was adjusted to 5 kg / cm ² , the hydrogen gas was adjusted to 10 kg / cm ² , and the other treatments were carried out in the same manner as in Example 1 to obtain a copolymer. The results are shown in Table 1.

Comparative Example 2 A copolymer was obtained by treating EASC to 36 mmol and otherwise treating in the same manner as in Example 2, and the results are shown in Table 1.

According to the comparison between Example 2 and Comparative Example 2, when Al / V is larger than the requirement of the present invention, the polymerization activity is significantly decreased, the ethylene content of the obtained copolymer becomes too high, and the copolymer is It can be seen that the resin becomes a hard resin, lacks flexibility, and has reduced transparency.

Comparative Example 3 The polymerization temperature was 60 ° C., the blowing pressure of ethylene was 8 kg / cm ² , the hydrogen gas was 10 kg / cm ² , and the other treatments were the same as in Example 1 to obtain a copolymer. Shown in the table.

According to the comparison between Example 1 and Comparative Example 3, when the polymerization temperature is higher than the requirement of the present invention, the copolymer dissolves in the solvent,
When the extracted polymerization reaction product is cooled to room temperature, most of the copolymer is precipitated and becomes a sticky and highly sticky slurry, the polymerization activity is significantly reduced, and the resulting copolymer has a wide molecular weight distribution and breaks. It can be seen that the strength is low and the surface of the molded product is sticky.

Example 3 3 equipped with stirring blade, dry ice cooler and thermometer
The polymerization reaction was performed by a batch reaction using a glass polymerization device. First, the polymerization solvent 2 was charged into a polymerization vessel sufficiently replaced with N ₂ gas, and the temperature was adjusted to 0 ° C. using a dry ice-alcohol refrigerant. Then add ethylene gas, 1
A mixed gas of butene gas and hydrogen gas of 9: 1: 5 (molar ratio) was introduced at a constant flow rate of 15 / min from the upper part of the polymerization vessel,
After 30 minutes, the EAC solution was added with 30 mmol of Al atom, and a solution of a mixed reaction product of VOCl ₃ and ethyl alcohol in a ratio of 1: 1 (molar ratio) was added to V.
0.5 mmol of atoms was added to initiate the polymerization reaction. Reaction is 0
The reaction was stopped after 5 minutes by adding a small amount of methanol. Steam was blown into the reaction product to remove the polymerization solvent and unreacted monomer, and then the drying was carried out in the same manner as in Example 1. These polymerization conditions, polymerization results,
Table 2 shows the analysis results and physical properties of the produced copolymer.

Example 4 Instead of EASC, ethyl aluminum dichloride (hereinafter
(Hereinafter referred to as EADC), and other treatments were carried out in the same manner as in Example 3 to obtain a copolymer, and the results are shown in Table 2.

Comparative Example 4 Instead of EASC, diethyl aluminum chloride (hereinafter
DEAC) and other treatments were carried out in the same manner as in Example 3 to obtain a copolymer. The results are shown in Table 2.

According to the comparison between Example 3, Example 4 and Comparative Example 4, when the number of n in the organic chlorinated aluminum compound (RnAlCl _{3 −} n) deviates from the requirement of the present invention, the polymerization activity is not only significantly decreased. It can be seen that the obtained copolymer has a wide molecular weight distribution and the molded product has poor flexibility and transparency.

Comparative Example 5 Ethylene gas, 1-butene gas and hydrogen gas were mixed at a mixing ratio of 9: 2: 4 (molar ratio), a constant flow rate of 15 / min was applied, and otherwise the same treatment as in Example 3 was carried out to obtain a copolymer. The results are shown in Table 2.

From the comparison between Example 3 and Comparative Example 5, when the ethylene content in the copolymer is lower than the requirement of the present invention, a rubbery copolymer having extremely low strength is obtained, and the surface stickiness of the molded product is also low. I know that there is.

Example 5 Using the same apparatus as in Example 3, the mixing ratio of ethylene gas, propylene gas and hydrogen gas was set to 10: 1: 6 (molar ratio),
The same procedure as in Example 3 was performed except that the constant flow rate was 15 / min.

The results are shown in Table 2.

[Brief description of drawings]

FIG. 1 is a diagram showing a typical DSC pattern used for measuring the melting point of the copolymer of the present invention by DSC, and FIG. 2 is a flow chart of the method for producing an ethylene-α-olefin copolymer of the present invention. It is a figure.

Front page continued (72) Inventor Kenya Makino 2-11-24 Tsukiji, Chuo-ku, Tokyo Within Nippon Synthetic Rubber Co., Ltd. (56) Reference JP-A-49-55789 (JP, A) JP-A-48- 4592 (JP, A) JP 44-1437 (JP, B1) JP 55-30524 (JP, B2)

Claims (1)

[Claims] 1. When producing an ethylene-α-olefin copolymer from ethylene and a chain α-olefin having 3 to 10 carbon atoms, a soluble vanadium compound as a polymerization catalyst and a general formula RnAlCl _3- n (formula Wherein n is a number of 1.8 to 0.8 and R is an alkyl residue having 2 to 6 carbon atoms) and a catalyst comprising an organochlorinated aluminum compound represented by the formula (1) and the soluble vanadium compound (V) and Composition ratio Al / V (molar ratio) with organic chlorinated aluminum compound (Al) is 55 to 17
0, n-hexane, n-heptane or cyclohexane is used as a polymerization catalyst, and the polymerization temperature is + 30 ° C to -20 ° C.
The ethylene content is 75 to 90 wt% and the ratio Mw / Mn of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is 2 obtained by slurry-polymerizing the ethylene and the α-olphin.
~ 5, melting point (Tm) determined by differential scanning calorimeter (DSC)
Of 40 to 90 ° C. for producing an ethylene-α-olefin copolymer.