JPH0639499B2 - Method for producing crosslinked ultra high molecular weight polyethylene - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing ultrahigh molecular weight polyethylene, and more particularly to a method for producing an ultrahigh molecular weight polyethylene crosslinked product having excellent heat resistance, solvent resistance and dimensional stability.

Conventional technology and problems to be solved by the invention So-called ultra-high molecular weight polyethylene, which has a remarkably high molecular weight of about 1,000,000 or more, is an engineering plastic with excellent characteristics such as impact resistance, abrasion resistance, and self-lubrication. It is used in a wide range of fields such as food machinery such as hoppers, silos, various gears, lining materials, ski linings, civil engineering machinery, chemical machinery, agriculture, mining, and sports / registry.

In addition, since ultra-high molecular weight polyethylene has a much higher molecular weight than general-purpose polyethylene, if it can be highly oriented, it may be possible to obtain a stretched product with higher strength and elasticity than ever before. Various studies have been made.

However, the melting point of ultra high molecular weight polyethylene is 135 ° C.
The temperature is up to 140 ° C, which is lower than that of other engineering plastics, and the applications are naturally limited.

As a method for improving heat resistance, cross-linking between the molecules of a polymer is generally performed and a great effect is exhibited. As a crosslinking method, (a) a method of mixing an organic peroxide and crosslinking by heating, (b) a method of irradiating with an electron beam to perform crosslinking, and the like are generally used.

When cross-linking a polyethylene having a normal molecular weight of up to about 200,000 with a weight-average molecular weight with an organic peroxide, a method is used in which the organic peroxide is melt-mixed with the polyethylene and then heated and cross-linked during processing into a target molded article. However, in the case of ultra-high molecular weight polyethylene, it is impossible to melt-mix the organic peroxide because the melt viscosity at the time of melting is extremely high. As a method of mixing the organic peroxide, a method of dissolving the ultra-high molecular weight polyethylene in a soluble organic solvent and dissolving the organic peroxide therein, and then removing the solvent, or the organic peroxide Although a method of dissolving the polymer in the solution and immersing the polymer in the solution to remove the organic solvent is used, these methods do not cause effective crosslinking unless a large amount of the organic peroxide is used.

On the other hand, in the method of cross-linking by irradiating with an electron beam, cross-linking is accelerated by irradiating the ultra-high molecular weight polyethylene with an electron beam, while deterioration of polyethylene also occurs in parallel and the original characteristics of the ultra-high-molecular-weight polyethylene are easily damaged. It is desirable to be able to achieve cross-linking with the lowest possible irradiation dose.

In polyethylene normal molecular weight, although the ethylene and a diene compound to increase the introduced cross-linkable double bonds in the molecule effecting copolymerization in the presence of H ₂ molecular weight regulator are known, the H ₂ unsaturated When the copolymerization is carried out in the presence or at a reduced concentration, the copolymerizability of the diene compound is extremely poor. Therefore, the condition for obtaining a copolymer having a normal molecular weight, or simply increasing the proportion of the diene compound can improve the crosslinkability. It is not possible to introduce into the polymer more than 0.1 mol% of double bonds which are effective.

Based on the above, the present inventors have conducted diligent studies to solve these problems, and as a result, obtained ethylene and a diene compound by copolymerizing with a specific catalyst under specific polymerization conditions. The present invention has been completed by finding the fact that ultra high molecular weight polyethylene having a double bond in the molecule to be used has excellent crosslinkability.

That is, according to the present invention, a solid catalyst component obtained by supporting a titanium compound or a titanium compound and a vanadium compound on an inorganic solid compound containing magnesium is mixed with at least 1 part of ethylene by a catalyst composed of an organoaluminum compound.
When copolymerizing with a diene compound of a kind, the molar ratio of diene compound / ethylene at the time of polymerization is 0.5 or more and the molar ratio of Ti and V / diene compound in the solid catalyst component is 1.0 × 10 ⁻⁵ or more. A method for producing a crosslinked product of ultra-high molecular weight polyethylene, which comprises copolymerizing under conditions to form a copolymer having an intrinsic viscosity of 5 dl / g or more in decalin at 135 ° C. and then crosslinking the copolymer. .

EFFECTS OF THE INVENTION By using ultrahigh molecular weight polyethylene having a double bond content of 0.1 mol% or more obtained by using the above-mentioned predetermined conditions, a small amount of organic peroxide can be used when crosslinking with an organic peroxide. It is possible to carry out effective cross-linking by means of, and also in the case of cross-linking by means of electron beams, it is possible to carry out effective cross-linking with a small irradiation dose and prevent deterioration due to molecular cleavage.

The ultrahigh molecular weight polyethylene crosslinked product of the present invention has high strength and high elastic modulus, and at the same time is excellent in heat resistance, solvent resistance and dimensional stability, and the crosslinking process can be economically performed.

A more specific method for producing the ultrahigh molecular weight polyethylene crosslinked product of the present invention will be described below.

Hydrogen concentration of ethylene and diene compound 0 to about 10 mol%
By polymerizing in a solvent or in the gas phase,
Ultrahigh molecular weight polyethylene having an intrinsic viscosity of 5 dl / g or more, preferably 10 dl / g to 30 dl / g in decalin at ℃ is produced. Those having an intrinsic viscosity of less than 5 dl / g are not preferable because the original abrasion resistance and mechanical strength of ultra high molecular weight polyethylene are poor.

5-vinyl-2-norbornene as the diene compound,
Non-conjugated polycyclic dienes such as 5-ethylidene-2-norbornene, dicyclopentadiene, norbornadiene, propenylnorbornene, 1,4-pentadiene,
1,4-hexadiene, 1,5-hexadiene, 3-methyl-1,4-pentadiene, 1,4-heptadiene,
Non-conjugated aliphatic dienes such as 1,5-heptadiene, 1,6-heptadiene, 3-methyl-1,4-hexadiene, 3-methyl-1,5-hexadiene, 1,3-butadiene, isoprene, 1, 3-pentadiene, 1,3-
Examples thereof include conjugated aliphatic dienes such as hexadiene, 2,3-dimethyl-1,3-butadiene, and 2-phenyl-1,3-butadiene.

The polymerization catalyst used at this time is composed of an inorganic solid compound containing Mg and a Ti catalyst or a Ti catalyst and a V compound supporting a solid catalyst component and an organoaluminum compound (described later), and the polymerization pressure is 0 to 70 kg. /cm
² · G, a polymerization temperature of 0 to 90 ° C., preferably from 20 to 80 ° C.
In a solvent or in the gas phase. As the polymerization solvent, an organic solvent inert to the Ziegler type catalyst is used. Specifically, butane, pentane, hexane, heptane, octane,
Examples thereof include saturated hydrocarbons such as cyclohexane and aromatic hydrocarbons such as benzene, toluene and xylene. Further, depending on the necessity of molding and processing of the ultrahigh molecular weight polyethylene to be obtained, decalin, tetralin, decane, kerosene, etc. High boiling organic solvents can also be mentioned.

In the present invention, in order to copolymerize ethylene and at least one diene compound to produce an ultrahigh molecular weight polyethylene effective for crosslinking, the diene compound / ethylene molar ratio is 0.5 or more, preferably 1.0 or more. Under the condition that the molar ratio of Ti and V (when V compound is used in combination) / diene compound in the solid catalyst component is 1.0 × 10 ⁻⁵ or more, preferably 2.0 × 10 ⁻⁵ or more. It is necessary to polymerize at 1, and if either of these conditions is not satisfied, the content of the diene compound in the polyethylene will be small and the desired crosslinking effect will not be exhibited.

In the calculation of the above molar ratio, the molar amount of dissolved ethylene is used in the case of polymerization in a solvent.

Further, α-olefin other than ethylene may be used as the third polymerization component, and the α-olefin at this time may be propylene, butene-1,4-methyl-pentene-1, hexene-1, octene-. For example, those used for the copolymerization of ethylene with a conventional Ziegler type catalyst can be used.

Next, the catalyst used for producing the ultrahigh molecular weight polyethylene of the present invention is composed of an organoaluminum compound and a solid catalyst component containing Mg and Ti or Mg, Ti and V as essential components as described above.

Here, the solid catalyst component is a titanium compound or a titanium compound and a vanadium compound supported on an inorganic solid compound containing magnesium by a known method.

The inorganic solid compound containing magnesium is metallic magnesium, magnesium hydroxide, magnesium carbonate, magnesium oxide, magnesium chloride, etc., and a double salt containing a metal and a magnesium atom selected from silicon, aluminum, and calcium, a complex oxide, Carbonates, chlorides, hydroxides and the like, as well as these inorganic solid compounds, organic oxygen-containing compounds such as water, alcohols, phenols, ketones, aldehydes, carboxylic acids, esters, polysiloxanes and acid amides; metal alkoxides. , Inorganic oxygenates such as metal oxyacid salts; thiols,
Organic sulfur-containing compounds such as thioethers; sulfur dioxide,
Inorganic sulfur-containing compounds such as sulfur trioxide and sulfuric acid; benzene,
A monocyclic or polycyclic aromatic hydrocarbon compound such as toluene, xylene, anthracene, or phenols; treated or reacted with a halogen-containing compound such as chlorine, hydrogen chloride, a metal chloride, or an organic halide.

Examples of the titanium compound supported on the inorganic solid compound include titanium halides, alkoxy halides,
Alkoxides, halogenated oxides, etc., and tetravalent or trivalent titanium compounds are preferable. Specific examples of the tetravalent titanium compound include Ti (OR) _n X _4-n (wherein R represents an alkyl group having 1 to 20 carbon atoms, an aryl group or an aralkyl group, and X represents a halogen atom). And n is 0 ≦ n ≦ 4) is preferable, and titanium tetrachloride, titanium tetrabromide, titanium tetraiodide, monomethoxytrichlorotitanium, dimethoxydichlorotitanium, trimethoxymonochlorotitanium, tetra Methoxytitanium, monoethoxytrichlorotitanium, diethoxydichlorotitanium, triethoxymonochlorotitanium, tetraethoxytitanium, monoisopropoxytrichlorotitanium, diisopropoxydichlorotitanium, triisopropoxymonochlorotitanium, tetraisopropoxytitanium, monobutoxytrichlorotitanium, Dibutoxydichlorotitanium, mono Examples thereof include tetravalent titanium compounds such as pentoxytrichlorotitanium, monophenoxytrichlorotitanium, diphenoxydichlorotitanium, triphenoxymonochlorotitanium and tetraphenoxytitanium. The trivalent titanium compound is a trivalent titanium compound obtained by reducing titanium tetrahalide such as titanium tetrachloride or titanium tetrabromide with hydrogen, aluminum, titanium or an organometallic compound of Group I to III metal of the periodic table. Valent titanium compound; general formula Ti (OR) _m X _4-m (wherein R represents an alkyl group, an aryl group or an aralkyl group having 1 to 20 carbon atoms, X represents a halogen atom, and m represents 0 < a tetravalent halogenated alkoxytitanium with m <4)
~ Trivalent titanium compounds obtained by reduction with organometallic compounds of Group III metals. Of these titanium compounds, tetravalent titanium compounds are particularly preferable. Also,
As the vanadium compound, a compound of tetravalent vanadium such as vanadium tetrachloride, vanadium oxytrichloride,
Examples thereof include pentavalent vanadium compounds such as orthoalkyl vanadate and trivalent vanadium compounds such as vanadium trichloride. Specific solid catalyst components include Japanese Patent Publication No. 51-3514, Japanese Patent Publication No. 50-23864, Japanese Patent Publication No. 51-152, and Japanese Patent Publication No. 52-151.
11, JP-A-49-106581, JP-B-52-11710, JP-B-51-153,
Specific examples include those disclosed in JP-A-56-95909.

Further, as the other solid catalyst component, for example, a reaction product of a Grignard compound and a titanium compound can be used. JP-B-50-39470, JP-B-54-12953, JP-B-54-12954, 57-7
Specific examples include those described in Japanese Patent No. 9009,
In addition, JP-A-56-47407 and JP-A-57
A solid catalyst component in which an inorganic oxide is used in combination with an optionally used organic carboxylic acid ester described in JP-A-187305 and JP-A-58-21405 can also be used.

Examples of the organoaluminum compound of the present invention include R ₃ Al, R ₂ AlX, RAlX ₂ , R ₂ AlOR, RAl (OR) X and R ₃ Al ₂ X ₃ (where R is an alkyl group having 1 to 20 carbon atoms). Group, an aryl group or an aralkyl group, X represents a halogen atom, and R may be the same or different, and is preferably triethylaluminum, triisobutylaluminum, trihexylaluminum, trioctyl. Aluminum, diethylaluminum chloride, diethylaluminum ethoxide, ethylaluminum sesquichloride, and mixtures thereof. The amount of the organoaluminum compound used is not particularly limited, but is usually 0.
It can be used in an amount of 1 to 1000 mol times.

The above catalyst system is used to synthesize the ultrahigh molecular weight polyethylene of the present invention.

Prior to the polymerization reaction of the present invention, the polymerization reaction may be carried out after contacting the α-olefin with the catalyst system of the present invention.

In the present invention, it has been found that the ultra-high molecular weight polyethylene thus synthesized can be easily and economically crosslinked, and the crosslinked product has excellent properties.

The crosslinking method used in the present invention is not particularly limited,
In particular, crosslinking with an organic peracid and crosslinking with irradiation are suitable.

The organic peroxide used in the present invention is 2,5-dimethyl-2,5-di (t-butylperoxy) hexane,
Di-t-butyl peroxide, di (t-butylperoxy) diisopropylbenzene, di (t-butylperoxy) diisobutylbenzene, dicumyl peroxide, t
-Butyl cumyl peroxide, t-butyl peroxybenzoate, 1,1-bis (t-butyl peroxy)-
Examples thereof include 3,3,5-trimethyl peroxide, benzoyl peroxide, p-chlorobenzoyl peroxide, and the like, and particularly 2,5-dimethyl-2,5-di (t-
Butyl peroxy) hexane is suitable.

The method of mixing the organic peroxide with the ultra-high molecular weight polyethylene of the present invention is not particularly limited, but it is dissolved in an organic solvent capable of dissolving the organic peroxide, and the powder is immersed in the organic solvent and the organic solvent is mixed and stirred. The method of removing is preferable.

The amount of the organic peroxide used is 0.3 to 1 wt% based on the ultrahigh molecular weight polyethylene.

Crosslinking time and temperature are determined by the molecular weight of the organic peroxide and ultra high molecular weight polyethylene used.

On the other hand, the radiation used in the case of radiation crosslinking is not particularly limited, and alpha rays, beta rays, gamma rays,
Any of electron beams and the like can be used.

The irradiation dose is 5 to 3 when crosslinking ordinary polyethylene.
Although it is 0 Mrad, 1 to 5 Mrad is sufficient in the case of the ultrahigh molecular weight polyethylene of the present invention.

Hereinafter, the present invention will be specifically described in detail with reference to Examples, but the present invention is not limited thereto.

Example 1 (a) Preparation of solid catalyst component Commercially available anhydrous magnesium chloride 10 g and silicon tetraethoxide 3.3 g in a stainless steel pot having an internal volume of 400 ml containing 25 stainless steel balls each having a diameter of 1/2 inch. And phosphorus oxychloride 0.7g
Into a nitrogen atmosphere, ball milling was performed at room temperature for 5 hours, 2 g of titanium tetrachloride was added, and ball milling was performed for 16 hours. 1 g of the solid catalyst component obtained after ball milling contained 32 mg of titanium.

(b) Polymerization 2 The autoclave made of stainless steel and equipped with an induction stirrer was replaced with nitrogen, 1000 ml of hexane was added, 3.3 mmol of triethylaluminum and 50 mg of the solid catalyst component were added, and the temperature was raised to 70 ° C. with stirring. The system becomes 1.3 kg / cm ² · G by the vapor pressure of hexane, and then 135 g of 5-vinyl-2-norbornene is added together with ethylene, and ethylene is added until the total pressure reaches 10 kg / cm ² · G to polymerize. Was started and polymerization was carried out for 1 hour while maintaining the pressure of the autoclave at 10 kg / cm ² · G. 5-vinyl-2-norbornene during polymerization /
The ethylene molar ratio is 1.2, and Ti in the solid catalyst component is
The / 5-vinyl-2-norbornene molar ratio was 3 × 10 ^-5 .

After completion of the polymerization, the polymer slurry was transferred to a beaker, and hexane and unreacted 5-vinyl-2-norbornene were removed under reduced pressure to obtain an intrinsic viscosity of 14.9 dl / g (135 ° C. in decalin), a density of 0.930, and a bulk density. 62 g of 0.26 white ethylene copolymer resin was obtained.

According to infrared spectroscopy, the content of 5-vinyl-2-norbornene in the copolymer was 0.18 mol%.

(c) Electron beam cross-linking The obtained copolymer (3 g) was filled in a mold at 30 ° C., pressure 1
After pre-molding at 00kg / cm ² · G for 10 minutes, 200 ℃,
Preheat for 10 minutes at 200 ℃, pressure 150kg / cm ² · G
Melt-mold for 10 minutes at 30 ℃, pressure 100kg / cm ² 1
After cooling for 0 minutes, a sheet of 10 cm × 10 cm × 0.3 mm thickness was obtained.

The resulting sheet was crosslinked by irradiating it with an electron beam of 0.5-20 Mrad under N ₂ .

The gel fraction was measured for each of the films crosslinked at different irradiation doses.

For the gel fraction, cut the sample film into about 2 mm square,
Wrap in 60 mesh stainless steel wire mesh at 130 ℃
Extraction was carried out in dichlorobenzene for 24 hours, and the gel fraction was calculated from the insoluble content. The results are shown in Fig. 1.

As is clear from FIG. 1, the copolymer of the present invention is sufficiently crosslinked even at a low irradiation dose of 2 Mrad.

As a heat resistance test, the displacement under a load of 250 g was measured using a Bicatt softening point measuring device. As shown in FIG. 2, the copolymer of the present invention crosslinked with an electron beam of 2 Mrad had a significantly smaller displacement than that of Comparative Example 1, and the polymer of Comparative Example 1 was crosslinked with 20 Mrad. The values were almost the same.

(d) Crosslinking of organic peroxide To a 300 cc beaker, 100 cc of acetone and 0.08 g of 2,5-dimethyl-2,5-di (t-butylperoxy) hexane were added and dissolved to obtain a product of the present invention. 10 g of the copolymer was added and well dispersed. After that, acetone was completely removed by air-drying for one day and vacuum drying at 60 ° C. for 1 hour. 3 g of the obtained polymer was filled in a mold, preformed at 30 ° C. and a pressure of 100 kg / cm ² · G for 10 minutes, and then preheated at 200 ° C. for 10 minutes to 200
℃, pressure 150kg / cm ² · G crosslinked for 10 minutes at 30 ℃,
10 cm freshly cooled for 10 minutes at a pressure of 100 kg / cm ² · G
A sheet having a width of 10 cm and a thickness of 0.3 mm was obtained. When the gel fraction was measured using the obtained sheet in the same manner as in Example 1 (c), the gel fraction was 72%.

The autoclave with a stainless steel induction stirrer of Comparative Example 12 was replaced with nitrogen, 1000 ml of hexane was added, 1 mmol of triethylaluminum and 15 mg of the solid catalyst component obtained in Example 1 (a) were added, and the temperature was raised to 70 ° C. with stirring. Warmed. System at the vapor pressure of hexane is becomes 1.3kg / cm ² · G, then initiate polymerization by Harikon until the ethylene total pressure 10kg / cm ² · G, the pressure in the autoclave 10 kg / cm ² · Polymerization was carried out for 1 hour while keeping it at G.

After the polymerization was completed, the polymer slurry was transferred to a beaker, hexane was removed under reduced pressure, and 110 g of a white ethylene polymer resin having an intrinsic viscosity of 19.7 dl / g (135 ° C. in decalin), a density of 0.940, and a bulk density of 0.32. Obtained.

No double bond was present in the copolymer by infrared spectroscopy.

This resin was subjected to electron beam crosslinking in the same manner as in Example 1 (c).
The results are shown in Fig. 1.

Comparative Example 2 The stainless steel autoclave with an induction stirrer of 2 was replaced with nitrogen, 1000 ml of hexane was added, 1 mmol of triethylaluminum and 1 mg of a solid catalyst were added,
The temperature was raised to 70 ° C. with stirring. The system becomes 1.3 kg / cm ² · G by the vapor pressure of hexane, and then 5-vinyl-2.
-Norbornene (27 g) was added together with ethylene, and ethylene was added until the total pressure became 10 kg / cm ² · G to start the polymerization. Thereafter, ethylene was continuously introduced so that the total pressure was 10 kg / cm ² · G, and the polymerization was carried out for 1 hour.
The 5-vinyl-norbornene / ethylene molar ratio during the polymerization was 0.24, and the Ti / 5-vinyl-2-norbornene molar ratio in the solid catalyst component was 4.5 × 10 ⁻⁵ .

After completion of the polymerization, the polymer slurry was transferred to a beaker, and hexane and unreacted 5-vinyl-2-norbornene were removed under reduced pressure to obtain an intrinsic viscosity of 18.2 dl / g (135 ° C. in decalin), a density of 0.937, and a bulk density of 0. 65 g of a white polyethylene copolymer of 0.30 was obtained.

According to infrared spectroscopy, the content of 5-vinyl-2-norbornene in the copolymer was 0.038 mol%.

This resin was subjected to electron beam crosslinking in the same manner as in Example 1 (c).
The results are shown in Fig. 1.

Comparative Example 3 In Comparative Example 2, 13-vinyl-5-norbornene was used.
Polymerization was carried out in the same manner as in Comparative Example 2 except that 5 g was used. The 5-vinyl-2-norbornene / ethylene molar ratio at the time of polymerization was 1.2, and the Ti / 5-vinyl-2-norbornene molar ratio in the solid catalyst component was 0.9.
It was × 10 ^-5 .

After completion of the polymerization, the polymer slurry was transferred to a beaker and hexane and unreacted 5-vinyl-2-norbornene were removed under reduced pressure,
White polyethylene 4 with an intrinsic viscosity of 16.0 dl / g (135 ° C in decalin), a density of 0.935, and a bulk density of 0.25
5 g was obtained.

According to infrared spectroscopy, the content of 5-vinyl-2-norbornene in the copolymer was 0.06 mol%.

This resin was subjected to electron beam crosslinking in the same manner as in Example 1 (c).
The results are shown in Fig. 1.

Example 2 2.6% triethylaluminum was used in Example 1 (b).
Polymerization was carried out in the same manner as in Example 1 (b) except that 40 mg of the solid catalyst component was used. The molar ratio of 5-vinyl-2-norbornene / ethylene during polymerization was 1.2, and Ti / 5-vinyl-2 in the solid catalyst component was
The norbornene molar ratio was 23 × 10 ^-5 .

The polymer yield was 50 g and the intrinsic viscosity was 15.5 dl /
g (in decalin at 135 ° C.), the density was 0.931 and the bulk density was 0.26.

According to infrared spectroscopy, the content of 5-vinyl-2-norbornene in the copolymer was 0.16 mol%.

When this resin was irradiated with an electron beam of 2 Mrad in the same manner as in Example 1 (c), the gel fraction was 65%.

Example 3 (a) Production of solid catalyst component 3.3 g of silicon tetraoxide in Example 1 (a)
A catalyst was prepared in the same manner as in Example 1 (a) except that 1.9 g of boron triethoxide was used instead of. 1 g of the obtained solid catalyst component contained 35 mg of titanium.

(b) Polymerization Using the same autoclave as in Example 1 (b), 1000 ml of hexane was added, and diethylaluminum chloride 5 was added.
Millimol and 50 mg of the solid catalyst component were added, and the temperature was raised to 70 ° C. with stirring. Hexane vapor pressure 1.3 kg
/ Cm ² · it becomes a G, stakeout the followed 5-vinyl-2-norbornene 135g with ethylene, and polymerization was started by Harikon until the ethylene total pressure 10kg / cm ² · G. Thereafter, ethylene was continuously introduced so that the total pressure would be 10 kg / cm ² · G, and polymerization was carried out for 1 hour. The molar ratio of 5-vinyl-2-norbornene / ethylene at the time of polymerization was 1.2, and Ti / 5-vinyl-2 in the solid catalyst component was
The norbornene molar ratio was 3.3 × 10 ⁻⁵ .

Polymer yield is 35g and intrinsic viscosity is 22.3dl / g
(135 ° C, in decalin), the density was 0.932 and the bulk density was 0.24.

According to infrared spectroscopy, the content of 5-vinyl-2-norbornene in the copolymer was 0.11 mol%.

When this resin was irradiated with an electron beam of 2 Mrad as in Example 1 (c), the gel fraction was 61%.

Examples 4 to 6 Polymerization was performed in the same manner as in Example 1 (b) except that the comonomer shown in Table 1 was used instead of 5-vinyl-2-norbornene in Example 1 (b). Ivy. Further, electron beam crosslinking was carried out in the same manner as in Example 1 (c) to measure the gel fraction. The results are shown in Table 1.

Example 7 Instead of 2.0 g of titanium tetrachloride in Example 1 (a), 0.5 g of VO (OC ₂ H ₅ ) ₃ and 2.0 g of titanium tetrachloride were used.
A catalyst was prepared in the same manner as in Example 1 (a) except that was used. 7.6 was added to 1 g of the obtained solid catalyst component.
It contained mg vanadium and 30.6 mg titanium.

(b) Polymerization Using the same autoclave as in Example 1 (b), 1000 ml of hexane was added, 6 mmol of triethylaluminum and 70 mg of the solid catalyst component were added, and the temperature was raised to 70 ° C with stirring. The vapor pressure of hexane is 1.3 kg / system.
cm ・ G, but then 5-vinyl-2-norbornene 1
55 g of ethylene is added together with ethylene, and the total pressure of ethylene is 1
Polymerization was started by pouring it to 0 kg / cm ² · G, and polymerization was carried out for 3 hours while maintaining the pressure of the autoclave at 10 kg / cm ² · G. The 5-vinyl-2-norbornene / ethylene molar ratio at the time of polymerization was 1.3, and the Ti and V / 5-vinyl-2-norbornene molar ratio in the solid catalyst component was 4.2.

The polymer yield was 126 g and the intrinsic viscosity was 15.1 dl.
/ G (135 ° C, in decalin), the density was 0.932 and the bulk density was 0.28.

According to infrared spectroscopy, the content of 5-vinyl-2-norbornene in the copolymer was 0.15 mol%.

When this resin was irradiated with an electron beam of 2 Mrad as in Example 1 (c), the gel fraction was 58%.

Example 8 (a) Preparation of solid catalyst component Commercially available anhydrous magnesium oxide 10 g and silicon tetraethoxide 3.3 g in a stainless steel pot having an internal volume of 400 ml containing 25 stainless steel balls each having a diameter of 1/2 inch. And phosphorus oxychloride 0.7g
Was added, and ball milling was performed at room temperature for 5 hours in a nitrogen atmosphere. Then, 2 g of titanium tetrachloride was added, and ball milling was further performed for 16 hours. 1 g of the solid catalyst component obtained after ball milling contained 32 mg of titanium.

(b) Polymerization 2 The autoclave with a stainless steel electromagnetic induction stirrer was replaced with nitrogen, 1000 ml of hexane was added, 3.3 mmol of triethylaluminum and 50 mg of the solid catalyst component.
Was added and the temperature was raised to 70 ° C. with stirring. The system becomes 1.3 kg / cm ² · G by the vapor pressure of hexane, and then 135 g of 5-vinyl-2-norbornene is added together with ethylene, and ethylene is added until the total pressure reaches 10 kg / cm ² · G to polymerize. To start the autoclave pressure 10kg
Polymerization was carried out for 1 hour while maintaining the temperature at / cm ² · G. The 5-vinyl-2-norbornene / ethylene molar ratio at the time of polymerization was 1.2, and Ti / in the solid catalyst component /
The 5-vinyl-2-norbornene molar ratio was 3 × 10 ⁻⁵ .

After the polymerization was completed, the polymer slurry was transferred to a beaker, and hexane and unreacted 5-vinyl-2-norbornene were removed under reduced pressure to obtain an intrinsic viscosity of 15.8 dl / g (135 ° C in decalin), a density of 0.932, and a bulk density. 55 g of 0.25 white polyethylene copolymer resin was obtained.

According to infrared spectroscopy, the content of 5-vinyl-2-norbornene in the copolymer was 0.16 mol%.

(c) Electron beam cross-linking The obtained copolymer (3 g) was filled in a mold and the temperature was adjusted to 30 ° C and the pressure was adjusted to 10
After pre-molding at 0 kg / cm ² · G for 10 minutes, 200 ℃, 1
After preheating for 0 minutes, the mixture is melt-molded for 10 minutes at 200 ° C. and a pressure of 150 kg / cm ² · G, and cooled at 30 ° C. for 10 minutes at a pressure of 100 kg / cm ² · G. Vertical 10 cm × width 10 cm × thickness 0.3
I got a sheet of mm. The obtained sheet was crosslinked by irradiating it with an electron beam of ₂ Mrad under N ₂ .

For the gel fraction, cut the sample film into about 2 mm square,
Wrap it in 60 mesh stainless steel wire mesh and keep it at 130 ℃
-Extraction was carried out for 24 hours in dichlorobenzene, and the gel fraction was calculated from the proportion of the insoluble matter and found to be 65%.

Example 9 (a) Preparation of solid catalyst component Commercially available anhydrous magnesium carbonate 10 g and silicon tetraethoxide 3.3 g in a stainless steel pot having an internal volume of 400 ml containing 25 stainless steel balls each having a diameter of 1/2 inch. And phosphorus oxychloride 0.7g
Was charged, and ball milling was performed at room temperature for 5 hours in a nitrogen atmosphere. Then, 2 g of titanium tetrachloride was added, and ball milling was further performed for 16 hours. 1 g of the solid catalyst component obtained after ball milling contained 32 mg of titanium.

(b) Polymerization Polymerization was carried out in the same manner as in Example 8. The molar ratio of 5-vinyl-2-norbornene / ethylene at the time of polymerization was 1.2, and Ti / 5-vinyl-2 in the solid catalyst component was
The norbornene ratio was 3 × 10 ^-5 .

The polymer yield was 52 g and the intrinsic viscosity was 15.2 dl /
g, the density was 0.935, and the bulk density was 0.27.

According to infrared spectroscopy, the content of 5-vinyl-2-norbornene in the copolymer was 0.14 mol%.

(c) Electron beam cross-linking When this resin was irradiated with an electron beam of 2 Mrad in the same manner as in Example 8 (c), the gel fraction was 63%.

Example 10 (a) Preparation of solid catalyst component Commercially available anhydrous magnesium chloride 10 g and silicon tetraethoxide 2.3 g in a stainless steel pot having an internal volume of 400 ml containing 25 stainless steel balls each having a diameter of 1/2 inch. And phosphorus oxychloride 1.7g
Was added, ball milling was performed at room temperature for 5 hours in a nitrogen atmosphere, 3.6 g of chlorotributoxytitanium was added, and ball milling was further performed for 16 hours. 1 g of the solid catalyst component obtained after ball milling contained 32 mg of titanium.

(b) Polymerization Polymerization was carried out in the same manner as in Example 8. The molar ratio of 5-vinyl-2-norbornene / ethylene at the time of polymerization was 1.2, and Ti / 5-vinyl-2 in the solid catalyst component was
The norbornene ratio was 3 × 10 ^-5 .

The polymer yield was 50 g and the intrinsic viscosity was 16.3 dl /
g, the density was 0.933, and the bulk density was 0.26.

According to infrared spectroscopy, the content of 5-vinyl-2-norbornene in the copolymer was 0.15 mol%.

(c) Electron beam cross-linking This resin was irradiated with 2 Mrad of electron beam in the same manner as in Example 8 (c), and the gel fraction was 64%.

Example 11 (a) Production of solid catalyst component Commercially available anhydrous magnesium chloride 10 g and silicon tetraethoxide 3.3 g in a stainless steel pot having an internal volume of 400 ml containing 25 stainless steel balls each having a diameter of 1/2 inch. And phosphorus oxychloride 0.7g
Ball milling at room temperature for 5 hours in a nitrogen atmosphere, and then titanium trichloride (TiCl ₃ .1 / 3AlC
1 ₃ ) was added thereto, and ball milling was further performed for 16 hours. Solid catalyst component 1 obtained after ball milling
The g contained 37 mg of titanium.

(b) Polymerization Polymerization was carried out in the same manner as in Example 8. The molar ratio of 5-vinyl-2-norbornene / ethylene at the time of polymerization was 1.2, and Ti / 5-vinyl-2 in the solid catalyst component was
The norbornene ratio was 3.5 × 10 ^-5 .

The polymer yield was 66 g and the intrinsic viscosity was 18.2 dl /
g, the density was 0.931, and the bulk density was 0.27.

According to infrared spectroscopy, the content of 5-vinyl-2-norbornene in the copolymer was 0.16 mol%.

(c) Electron beam cross-linking When this resin was irradiated with an electron beam of 2 Mrad in the same manner as in Example 8 (c), the gel fraction was 62%.

Example 12 (a) Preparation of solid catalyst component Commercially available anhydrous magnesium chloride 10 g and silicon tetraethoxide 3.3 g in a stainless steel pot having an internal volume of 400 ml containing 25 stainless steel balls each having a diameter of 1/2 inch. And phosphorus oxychloride 0.7g
Was charged, and ball milling was performed at room temperature for 5 hours in a nitrogen atmosphere. Then, 0.5 g of vanadium tetrachloride and 2 g of titanium tetrachloride were added, and ball milling was further performed for 16 hours. 1 g of the solid catalyst component obtained after ball milling contained 8 mg of vanadium and 31 mg of titanium.

(b) Polymerization Polymerization was carried out in the same manner as in Example 8. The molar ratio of 5-vinyl-2-norbornene / ethylene at the time of polymerization was 1.2, and Ti / 5-vinyl-2 in the solid catalyst component was
The norbornene ratio was 3.7 × 10 ⁻⁵ .

The polymer yield was 50 g and the intrinsic viscosity was 13.6 dl /
g, the density was 0.930, and the bulk density was 0.24.

According to infrared spectroscopy, the content of 5-vinyl-2-norbornene in the copolymer was 0.17 mol%.

(c) Electron beam cross-linking When this resin was irradiated with an electron beam of 2 Mrad in the same manner as in Example 8 (c), the gel fraction was 67%.

[Brief description of drawings]

FIG. 1 shows the relationship between the electron beam irradiation dose and the gel fraction of the crosslinked ultrahigh molecular weight polyethylene of the present invention. FIG. 2 shows the relationship between the temperature and the amount of displacement of the crosslinked product of the present invention. In Figure 1 In Figure 2

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display area C08F 236: 02)

Claims (1)

[Claims] 1. An ethylene and at least one diene compound are copolymerized with a catalyst composed of an organoaluminum compound and a solid catalyst component comprising a titanium compound or a titanium compound and a vanadium compound supported on an inorganic solid compound containing magnesium. At that time, the molar ratio of the diene compound / ethylene during the polymerization was 0.5 or more, and the molar ratio of Ti and V / diene compound in the solid catalyst component was 1.0.
1 by copolymerizing under conditions of × 10 ^-5 or more
A process for producing a crosslinked product of ultra-high molecular weight polyethylene, which comprises producing a copolymer having an intrinsic viscosity of 5 dl / g or more in decalin at 35 ° C, and then crosslinking the copolymer.