JPH0481605B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a novel ethylene copolymer and a method for producing the same. More specifically, the present invention provides an ethylene copolymer useful for modifying polymers such as electrical insulation materials, foam materials, and engineering plastics. (Prior art) Olefin polymers, especially ethylene polymers, propylene polymers, etc., have excellent mechanical properties, processability, electrical properties, and other properties, and are economically inexpensive, so they are used as electrical insulating materials and foaming materials. It is used in various fields as a raw material or processed products such as films, pipes, and containers. Furthermore, olefin copolymers in which functional groups are introduced into the olefin polymer are also well known in order to improve the performance of the olefin polymer. For example, polyethylene itself has low dielectric loss and high dielectric strength, and when cross-linked, its heat resistance is greatly improved and is used as an excellent insulating material. It is desired to improve the performance as an insulator. As an attempt to improve the above-mentioned dielectric strength, a method of introducing an aromatic ring into an ethylene polymer has been proposed. For example, (1) A method of blending an aromatic polymer such as polystyrene with polyethylene or an olefin polymer (Japanese Patent Publication No. 38-20717, JP-A-50-142651, JP-A-52-54187) (2) A method of blending a block copolymer of styrene and conjugated dienes with polyethylene (Unexamined Japanese Patent Publication No. 1983-
41884) (3) A method of graft polymerizing styrene to polyethylene (Japanese Patent Publication No. 18760/1976) (4) A method of impregnating polyethylene with electrical insulating oil (Japanese Patent Application Laid-open No. 49-33938). Disclosed. However, none of the above methods has been able to sufficiently improve dielectric strength, and method (1) has poor compatibility between polyethylene or polyolefin and styrene polymer. Method (2) results in lower heat resistance and poor extrusion processability. Method (3) not only requires complicated equipment and processes to graft-polymerize styrene onto pre-crosslinked polyethylene in order to improve the breakdown strength of polyethylene against impact voltage in the high temperature range, but also requires complicated equipment and processes. It has the disadvantage that its breaking strength under impact voltage is inferior to that of untreated raw material polyethylene. Method (4) may cause the mixed electrical insulating oil to bleed due to long-term use or changes in the environment, and the effectiveness is inferior to the above three methods, so all methods are insufficient. However, there is a desire for an insulating material that is stable over a long period of time and has better performance. On the other hand, in the field of foam materials, polyethylene foam has the advantage of high elasticity and high strain recovery ability against repeated stress.
Mold foam molding can only mold simple shapes such as plate-shaped bodies, whereas bead foam molding (a method of foam molding using pre-expanded particles and steam heating) can produce foams with complex shapes. ,
Because gas diffuses quickly during foaming, it is difficult to set molding conditions, and it has not been possible to mold widely. It is also possible to blend particles pre-foamed by impregnating polystyrene and polyethylene with a foaming agent, which are good for bead foam molding, and foam molding, but such molding methods tend to cause the fusion of different types of beads. Unfortunately, it is impossible to produce a practical foam molded product. In recent years, a method for producing expandable polyethylene beads has been proposed which can improve the above-mentioned drawbacks, prevent the escape of the blowing agent, and obtain a foam with a high magnification. For example, (1) polyethylene particles, styrene monomer, and polymerization catalyst are dispersed in an aqueous medium, a physical blowing agent in the form of a gas or liquid is injected under normal conditions, and styrene is suspended and polymerized under heat and pressure to form foam. Method for producing polyethylene particles with modified properties (Special Publication 1973-
No. 2469, Special Publication No. 1973-32622, Special Publication No. 1973-32623
(2) A method in which polyethylene particles, a styrene monomer, and a polymerization catalyst are dispersed in an aqueous medium, and the resulting styrene-modified polyethylene particles are impregnated with a physical blowing agent after suspension polymerization under heating and pressure. Kimiaki
No. 52-10150, JP-A-49-85187, JP-A-49-
97884) (3) A method for producing porous materials by immersing a foaming agent into a polyolefin resin in which styrene is graft-polymerized by irradiation with ionizing radiation (Tokuko Sho
44-19382) have been proposed, but all of them require complicated steps and equipment. It is also a modifier for making a mixed composition of resins such as polyphenylene ether and polycarbonate, that is, resins called engineering plastics, and olefinic resins, or modifiers for impact resistance and processability of engineering plastics. Styrene-grafted polyolefins or styrene-based polymers are often used as
58-141240), however, engineering plastics and olefin polymers inherently have problems such as poor compatibility, and further improvements are desired. (Problems to be Solved by the Invention) In view of the above points, the present invention has been made as a result of intensive study.
The object of the present invention is to provide a novel ethylene copolymer that can more effectively improve the performance required for the above-mentioned electrical insulating materials, foamed materials, and modification of polymers, etc., without causing the conventional problems. (Means for solving the problem) The present invention has ethylene units of 85.0 to 99.995 mol% and the following formula () [However, R ₁ represents an alkylene group having 1 to 4 carbon atoms, and R ₂ and R ₃ represent a hydrogen atom, a chlorine atom, or a linear or branched alkyl group having 1 to 4 carbon atoms. ] 0.005 to mol % of comonomer units represented by: Contains 0-10 mol% of one type of monomer unit, density 0.860
~0.970g/ ^cm3 , melt index 0.05~100
g/10 min. A specific comonomer represented by the formula () that copolymerizes with ethylene is 1-phenyl-
1-styrylethane, 1-tolyl-1-styrylethane, 1-phenyl-1-styrylpropane, 1
At least one member selected from the group of -xylyl-1-styrylethane, 1-sec-butylphenyl-1-styrylethane, and 1-chlorophenyl-1-styrylethane, particularly 1-styrylethane among these.
Phenyl-1-styrylethane is preferred. The content of the above comonomer is 0.005 to 5 mol% as comonomer units in the copolymer, preferably 0.01 to 2
Mol% is appropriate. When the amount of the above comonomer is less than 0.005 mol%,
There is almost no modification effect of the ethylene copolymer, and if it exceeds 5 mol%, it becomes economically expensive, and especially in high-pressure radical polymerization, the amount of radicals consumed is large, making industrial production difficult. The advantage of doing so will be lost. Further, the monomer of the third component of the present invention is a C ₂ to _{C 3} monomer.
Acrylic acid or methacrylic esters such as vinyl esters of alkane carboxylic acids, methyl acrylic acid or methacrylate, ethyl acrylic acid or methacrylate, propyl acrylic acid or methacrylate, glycidyl acrylate or glycidyl methacrylate, acrylic acid, methacrylate acids, ethylenically unsaturated carboxylic acids or their anhydrides such as maleic acid, fumaric acid and maleic anhydride; acrylic acid or methacrylic acid amides such as acrylamide, methacrylic acid amide, maleic acid amide; at least one monomer. The content of the above monomer is used in the range of 0 to 10 mol%, preferably 0 to 7 mol%, and more preferably 0 to 5 mol%. The ethylene copolymer of the present invention can be produced using known methods such as ionic polymerization using a Ziegler type catalyst or radical polymerization under high pressure. However, for electrical insulating materials, high-pressure radical polymerization without catalyst residue is preferred. preferable. For example, in ionic polymerization using a Ziegler type catalyst, a solid catalyst component containing at least magnesium and titanium, such as magnesium metal, magnesium hydroxide, magnesium carbonate, magnesium oxide, magnesium chloride, etc., and a metal selected from silicon, aluminum, and calcium and magnesium atoms are used. double salts, double oxides, carbonates, chlorides, or hydroxides containing In the presence of a catalyst in which a titanium compound is supported on an inorganic solid compound containing magnesium by a known method and an organoaluminum compound is combined, polymerization is carried out in the same manner as the polymerization reaction of olefin using a normal Ziegler type catalyst. It is obtained by doing. That is, all reactions are carried out in a gas phase or in the presence of an inert solvent, or in the presence of a monomer itself as a solvent, in a state substantially free of oxygen, water, etc. The polymerization conditions for the above olefin are a temperature of 20 to 300℃, preferably 40 to 200℃, and a pressure of normal pressure to 70Kg/
cm ² ·g, preferably 2 to 60 kg/cm ² ·g. Although the molecular weight can be adjusted to some extent by changing polymerization conditions such as polymerization temperature and catalyst molar ratio, it is effectively carried out by adding hydrogen to the polymerization system. Furthermore, two or more stages of polymerization reactions with different polymerization conditions such as hydrogen concentration and polymerization temperature can be carried out without any problem. On the other hand, radical polymerization under high pressure refers to a polymerization pressure of 500 to 4000 Kg/cm ² , preferably 1000 to 3500 Kg/cm 2 .
Kg/ ^cm2 , reaction temperature 50~400℃, preferably 100~
free radical catalyst and chain transfer agent under 350°C conditions;
contacting the monomers simultaneously or in stages in a tank or tube reactor, if necessary in the presence of auxiliaries;
A method of polymerization. The free radical catalysts include customary initiators such as peroxides, hydroperoxides, azo compounds, amine oxide compounds, oxygen, and the like. Chain transfer agents include hydrogen, propylene, butene-1, C ₁ to _{C 20} or higher saturated aliphatic hydrocarbons, and halogen-substituted hydrocarbons, such as
Methane, ethane, propane, butane, isobutane, n-hexane, n-heptane, cycloparaffins, chloroform and carbon tetrachloride, C ₁ ~
Saturated aliphatic alcohols of C ₂₀ or more, such as methanol, ethanol, propanol and isopropanol, saturated aliphatic carbonal compounds of C ₁ to C ₂₀ or more, such as carbon dioxide, acetone and methyl ethyl ketone, and aromatic compounds, such as toluene, Examples include compounds such as diethylbenzene and xylene. (Function and Effects of the Invention) The ethylene copolymer of the present invention produced as described above, especially the ethylene copolymer obtained by high-pressure radical polymerization, is suitable for use as an electrical insulating material in comparison with ionic polymerization. There is little tree phenomenon due to the contamination of foreign matter such as residue, and the dielectric strength can be significantly improved. Furthermore, although the ethylene copolymer of the present invention is an excellent material as a modifier for foaming materials and polymers, other materials other than the ethylene copolymer of the present invention may be used as long as the properties of the ethylene copolymer are not significantly impaired. Olefin polymers (including copolymers), polyacrylonitrile, polyamide, polycarbonate, ABS resin, polystyrene, polyphenylene oxide,
Thermoplastic resins such as polyvinyl alcohol resins, vinyl chloride resins, vinylidene chloride resins, polyester resins, petroleum resins, thermosetting resins such as coumaron indene resins, phenolic resins, and melamine resins, ethylene-propylene copolymers Combined rubber (FPR, EPDM, etc.), SBR, NBR, butadiene rubber, IIR, chloroprene rubber, isoprene rubber,
At least one of synthetic rubber such as styrene-butadiene-styrene block copolymer or natural rubber, etc.
Can be used by mixing with seeds. In addition, in the present invention, organic/inorganic fillers, antioxidants, lubricants, various organic/inorganic pigments, ultraviolet inhibitors, antistatic agents, dispersants, copper damage inhibitors, neutralizing agents, blowing agents, plasticizers, etc. There is no problem in adding additives such as antifoaming agents, antifoaming agents, flame retardants, crosslinking agents, flowability improvers, weld strength improvers, and nucleating agents. (Example) Examples will be shown below. Examples 1 to 6 In each example, a metal autoclave-type reactor with an internal volume of 3.8 cm and a stirrer was sufficiently purged with nitrogen and ethylene, and then a predetermined amount of ethylene, n-hexane as a chain transfer agent, and 1- Phenyl-1-styrylethane was charged, di-tertiary butyl peroxide as a polymerization initiator was added, and the polymerization conditions were as shown in Table 1 at a polymerization pressure of 1600 Kg/cm ² , a polymerization temperature of 170°C, and a polymerization time of 1. Time polymerization was carried out. A part of the produced polymer was dissolved in heated carbon tetrachloride, reprecipitated by pouring it into a large amount of acetone, and further washed with acetone for purification and vacuum drying. The purified polymer was analyzed by ¹³ C-NMR and infrared spectroscopy to confirm the ethylene copolymer of the present invention. The analysis by ¹³ C-NMR was carried out using a solution of the polymer in orthodichlorobenzene at 130° C. and a resonance frequency of 100 MHz. The copolymerization was confirmed by predicting the chemical shift value of the spectrum of the ethylene copolymer from the ¹³ C-NMR spectrum of the comonomer, etc., and checking the agreement between the predicted value and the measured value. Infrared spectroscopic analysis was carried out by molding the polymer into a sheet approximately 500 μm thick by heat compression. The copolymer was confirmed mainly by the presence or absence of absorption attributed to the aromatic ring at 1600 cm ^-1 . The content of comonomer copolymerized in the polymer is ¹³ C
- the area of the signal in the NMR spectrum and
It was determined based on the absorbance at 1600 cm ^-1 in the infrared spectrum, and the results are shown in Table 1. In addition, the melt index and density of the produced polymer are measured using JIS
Performed in accordance with K6760.

[Table] Example 7 Using the apparatus of Example 1, 1700 g of ethylene and 1-phenyl-1-styrylethane as a comonomer were added.
30 g of ethylenic unsaturated monomer, 30 g of ethyl acrylate and a chain transfer agent (n-hexane) were charged, and a polymerization initiator (di-tertiary butyl peroxide) was added to the reactor at a pressure of 1600 Kg/cm ² .
Polymerization was carried out under the conditions of a polymerization temperature of 170° C. and a polymerization time of 1 hour, and the resulting polymer was treated and analyzed in the same manner as in Example 1. The results are shown in Table 2. However, the ethyl acrylate content in the copolymer was determined by molding a sheet with a thickness of approximately 200 μm, taking its infrared absorption spectrum, and determining the absorbance at the absorption peak at 860 cm ⁻¹ . Example 8 Using the apparatus of Example 1, 1700 g of ethylene and 1-phenyl-1-styrylethane as a comonomer were prepared.
30g, vinyl acetate as ethylenically unsaturated monomer
85g and a chain transfer agent (n-hexane) were charged, and a polymerization initiator (di-tert-butyl peroxide) was added, and the polymerization conditions were as follows: pressure 1600Kg/cm ² , polymerization temperature 170℃, and polymerization time 1 hour. Polymerization was carried out, and the resulting polymer was treated and analyzed in the same manner as in Example 1, and the results are shown in Table 2. However, the determination of the vinyl acetate content in the copolymer is
A sheet with a thickness of about 30 μm was molded, its infrared absorption spectrum was taken, and the amount was determined from the absorbance of the absorption peak at 1022 cm ⁻¹ . Example 9 Polymerization was carried out in the same manner as in Example 8 under the polymerization conditions shown in Table 2 using 150 g of vinyl acetate (abbreviated as VA) as the ethylenically unsaturated monomer as the third component.
The resulting polymer was treated and analyzed in the same manner as in Example 1, and the results are shown in Table 2. However, the determination of the VA content in the copolymer is as per Example 8.
I went in the same way. Example 10 Polymerization was carried out in the same manner as in Example 8 under the polymerization conditions shown in Table 2 using 20 g of methyl methacrylate (abbreviated as MMA) as the ethylenically unsaturated monomer as the third component, and the resulting polymer was It was treated and analyzed in the same manner as in Example 1, and the results are shown in Table 2. However, the quantification of the MMA content in the copolymer is based on the thickness
A 200 μm sheet was molded, its infrared absorption spectrum was taken, and the amount was determined from the absorption density of the absorption peak at 820 cm ⁻¹ . Example 11 Polymerization was carried out in the same manner as in Example 8 under the polymerization conditions shown in Table 2 using 2 g of maleic anhydride (abbreviated as MAn) as the ethylenically unsaturated monomer as the third component, and the resulting polymer was Processed in the same manner as in Example 1,
The results are shown in Table 2. However, the quantification of the MAn content of the copolymer is based on the thickness
A 200 μm sheet was molded, its infrared absorption spectrum was taken, and the amount was determined from the absorbance of the absorption peak at 1784 cm ⁻¹ . Example 12 Polymerization was carried out in the same manner as in Example 8 under the polymerization conditions shown in Table 2 using 20 g of acrylamide (abbreviated as Aam) as the ethylenically unsaturated monomer as the third component, and the resulting polymer was Processed in the same manner as in Example 1,
The results are shown in Table 2. However, the quantification of the Aam content of the copolymer is based on the thickness
A 200 μm sheet was molded, its infrared absorption spectrum was taken, and the amount was determined from the absorbance of the absorption peak at 3350 cm ⁻¹ .

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Claims (1)

[Claims] 1. 85.0 to 99.995 mol% of ethylene units and the following formula () [However, R ₁ represents an alkylene group having 1 to 4 carbon atoms, and R ₂ and R ₃ represent a hydrogen atom, a chlorine atom, or a linear or branched alkyl group having 1 to 4 carbon atoms. ] 0.005 to 5 mol % of comonomer units represented by , and selected from the group consisting of vinyl ester, acrylic acid or methacrylic ester, ethylenically unsaturated carboxylic acid or its anhydride, acrylic acid or methacrylic acid amide containing 0 to 10 mol% of at least one monomer, with a density of 0.860 to
0.970g/cm ³ , melt index 0.05~100
g/10 min. 2. The novel ethylene copolymer according to claim 1, wherein the comonomer is 1-phenyl-1-styrylethane. 3 Ethylene unit obtained by high-pressure radical polymerization at a pressure of 500 to 4000 Kg/cm ² and a temperature of 50 to 400°C
85.0~99.995 mol% and the following formula () However, R ₁ represents an alkylene group having 1 to 4 carbon atoms, and R ₂ and R ₃ represent a hydrogen atom, a chlorine atom, or a linear or branched alkyl group having 1 to 4 carbon atoms. 0.005 to 5 mol% of comonomer units represented by: and selected from the group consisting of vinyl esters, acrylic acid or methacrylic esters, ethylenically unsaturated carboxylic acids or their anhydrides, acrylic acid or methacrylic acid amides Contains 0-10 mol% of at least one monomer, density 0.860-
0.970g/cm ³ , melt index 0.05~100
A novel method for producing an ethylene copolymer with a production rate of 1.5 g/10 min.