CN101074275A - Extra high-molecular polythene catalyst and its production - Google Patents

Abstract

The invention discloses an ultra-high molecular weight polyethylene catalyst and a preparation method thereof. The catalyst comprises a catalyst main component and a cocatalyst, wherein the preparation of the catalyst main component is obtained through the following steps: (1) a magnesium halide compound and an alcohol (2) react the magnesium compound solution with an alkylaluminum chloride compound to obtain an intermediate product, and (3) react the intermediate product with a titanium compound and an electron donor. The ultra-high molecular weight polyethylene catalyst has the characteristics of high activity and high bulk density of the ultra-high molecular weight polyethylene.

Description

Ultra-high molecular weight polyethylene catalyst and preparation method thereof

technical field

The invention relates to a catalyst for ultra-high molecular weight polyethylene and a preparation method of the catalyst.

Background technique

According to the definition of ASTM4020, ultra-high molecular weight polyethylene (UHMWPE) is a linear polyethylene having a relative viscosity of 2.30 or higher, which is measured in 100 ml of a 0.05% decahydronaphthalene solution at 135°C. Compared with other polyethylenes, it has high wear resistance, excellent toughness and thermal stability, and is widely used in textile industry, mechanical engineering, chemical industry and mining industry.

For ultra-high molecular weight polyethylene, in addition to the size of the molecular weight can affect its mechanical properties and processing properties, the particle size and particle size distribution of ultra-high molecular weight polyethylene also play an important role. Therefore, the current research on UHMWPE catalysts mainly includes (1) improving the polymerization activity of the catalyst; (2) adjusting the catalyst formula to make the molecular weight adjustable within a certain range; (3) adjusting the particle size of the catalyst to improve particle size of polyethylene.

Chinese patent 94105011 discloses that dialkylmagnesium reacts with a halogenating agent to form a reactant mainly composed of the general formula Mg- _X , and then reacts with a titanium compound under the action of an electron donor, and the electron donor is selected from carboxylate and ether , ketones, amides, or oxygen-containing phosphorus or sulfides. Ultra-high molecular weight polyethylene with narrow particle size distribution and average particle diameter of 100-200um can be prepared. Although the particle size distribution of the polymer is ideal, the polymerization activity of the catalyst is not high.

The preparation method of the ultra-high molecular weight polyethylene catalyst disclosed in ZL00819563.3 includes i) forming a magnesium compound solution by contacting a mixture of a magnesium halide compound and an aluminum or boron compound with an alcohol, and ii) combining the solution with at least one hydroxyl-containing ester compound Reaction with a silicon compound having an alkoxy group (R _n Si(OR') _4-n ), and iii) adding a mixture of a titanium compound and a silicon compound (R _n SiCl _4-n ) to prepare a solid titanium catalyst. The catalyst has good activity, and the bulk density of polyethylene is relatively high, but in the preparation process of the catalyst, a large amount of titanium tetrachloride needs to be used for post-treatment, which will bring a greater cost to the post-treatment work in industrial production. problems and environmental pollution, and pre-polymerization should be carried out during catalyst polymerization.

Aiming at the different defects in the above prior art, the present invention will provide a catalyst for the preparation of ultra-high molecular weight polyethylene, which not only has excellent polymerization activity, but also can be directly used for the polymerization of ethylene without pre-polymerization, and at the same time Ethylene has relatively high bulk density and less fine powder content.

Contents of the invention

One of the technical problems to be solved by the present invention is to provide an ultra-high molecular weight polyethylene catalyst.

The second technical problem to be solved by the present invention is to provide a method for preparing an ultra-high molecular weight polyethylene catalyst.

The third technical problem to be solved by the present invention is to provide an application of an ultra-high molecular weight polyethylene catalyst in ethylene homopolymerization or copolymerization.

A kind of ultra-high molecular weight polyethylene catalyst, this catalyst comprises catalyst body component and cocatalyst, wherein the preparation of catalyst body component obtains by following steps:

(1) Magnesium halide compounds react with alcohol compounds and titanate compounds to form a magnesium compound solution,

(2) magnesium compound solution reacts with alkylaluminum chloride compound to obtain an intermediate product,

(3) The intermediate product is then reacted with a titanium compound and an electron donor.

The magnesium halide compounds described in the present invention include: magnesium dihalide compounds, such as magnesium chloride, magnesium bromide, magnesium iodide or magnesium fluoride; alkyl magnesium halide compounds, such as methyl magnesium halide, ethyl magnesium halide, propyl magnesium halide Magnesium halides, butyl magnesium halides, isobutyl magnesium halides, hexyl magnesium halides or pentyl magnesium halides; alkoxymagnesium halide compounds such as methoxymagnesium halides, ethoxymagnesium halides, isopropylmagnesium halides, butyl magnesium halides oxymagnesium halide or octoxymagnesium halide. Among the above compounds, one kind of magnesium halide compound may be used, or a mixture of two or more kinds of magnesium halide compounds may be used. Magnesium dihalide is preferred in the present invention, more preferably magnesium chloride.

Alcohols described in the present invention include alcohols with 4 to 20 carbon atoms, preferably alcohols with 4 to 10 carbon atoms, such as isobutanol, 2-ethylhexanol, 2-methylpentanol, 2-ethane butanol, octanol, etc. More preferred is 2-ethylhexanol.

The alkylaluminum chloride compound of the present invention can be represented by the general formula R ¹ _n AlCl _3-n , wherein R ¹ is an alkyl group with 1 to 14 carbon atoms, 1≤n<3, and the compound that can be used is such as monochloro Diethylaluminum, monoethylaluminum dichloride, diisopropylaluminum chloride, ethylaluminum sesquichloride, butylaluminum sesquichloride, etc., preferably diethylaluminum monochloride.

The titanate compounds described in the present invention can be represented by the general formula Ti(OR ² ) _b , wherein R ² is an alkyl group having 1 to 10 carbon atoms, and b is an integer of 1 to 4. Compounds that can be used such as titanium n-butyl titanate, isopropyl titanate, isobutyl titanate, n-hexyl titanate, amyl titanate, and the like. Preference is given to n-butyl titanate.

The electron donor of the present invention can be selected from ethers and esters. Ethers include diphenyl ether, cresyl ether, ethylphenyl ether, etc. Esters include benzoate esters and phosphate esters. Benzoate esters such as benzoic acid ethyl ester, diisobutyl terephthalate, di-n-butyl terephthalate, methyl benzoate, ethyl 2-hydroxybenzoate, ethyl 3-hydroxybenzoate, 4- Methyl hydroxybenzoate, etc.; phosphates include tributyl phosphate, triphenyl phosphite, etc.; silane compounds can also be selected as electron donors, including dimethyldimethoxysilane, diphenyldimethoxy Dimethyldiethoxysilane, diphenyldiethoxysilane, dimethyldiethoxysilane, etc. These two electron donors can also be used in combination. In the present invention, diphenyl ether and diphenyldimethoxysilane are preferred.

The titanium compound described in the present invention can be represented by the general formula Ti(OR ³ ) _m Cl _4-m , wherein R ³ is an alkyl group having 1 to 10 carbon atoms, 0≤m≤4, and compounds such as tetra Titanium chloride, n-butyl titanate, isopropyl titanate, methoxytitanium trichloride, dibutoxytitanium dichloride, tributoxytitanium chloride and the like. In the present invention, two different titanium compounds can be used in combination, for example, a titanium compound having at least one OR ³ group and titanium tetrachloride can be used in combination. In the present invention, only one titanium compound is preferably used, more preferably titanium tetrachloride.

The cocatalyst described in the present invention is an organoaluminum compound, including triethylaluminum, triisobutylaluminum, tri-n-hexylaluminum, etc. or a mixture thereof, preferably triethylaluminum.

A preparation method of ultra-high molecular weight polyethylene catalyst, comprising the following preparation steps:

(5) Magnesium halides, alcohol compounds, and titanate compounds are contacted and reacted in a hydrocarbon solvent to prepare a magnesium compound solution. The amount of titanate and alcohol compounds added is 2 to 10 mol of alcohol based on the amount of magnesium halide. /mol magnesium halide, 0.03～0.5mol titanate/mol magnesium halide;

(6) Add an alkylaluminum chloride compound to the magnesium compound solution and react to obtain a suspension. The amount of the alkylaluminum chloride compound is based on the amount of alcohol added, which is 0.3 to 1.0 mol alkylaluminum chloride/mol alcohol;

(7) Titanium compound, electron donor and above-mentioned suspension contact reaction, obtain catalyst body component, the consumption of titanium compound and the consumption of electron donor are all based on the consumption of magnesium halide, are respectively 0.25～2.0mol titanium compound/mol Magnesium halide, 0.1-0.8mol electron donor/mol magnesium halide;

(8) Ti in the catalyst main component and Al in the cocatalyst are contacted and reacted according to the molar ratio of 1: (30-300).

The preparation method of catalyst host component will be described in detail below:

The contact reaction of magnesium halide with alcohol compounds and titanate compounds in hydrocarbon solvents, the hydrocarbon solvents include aliphatic hydrocarbon compounds with 5-10 carbon atoms, such as n-pentane, isopentane, n-hexane alkane, n-heptane, n-octane, decane; alicyclic hydrocarbons, such as cyclohexane, methylcyclohexane; aromatic hydrocarbons, such as benzene, toluene or ethylbenzene. N-hexane and n-heptane are preferred in the present invention. The titanate and alcohol can be added dropwise or all at once. After the addition, the temperature is raised to 60-100° C., stirred and reacted for 1-4 hours to obtain a magnesium compound solution, and then cooled to room temperature for use. The amount of alcohol added is based on the amount of magnesium halide, 2-10mol alcohol/mol magnesium halide, preferably 3-8mol alcohol/mol magnesium halide; the amount of titanate compounds is 0.03-0.5mol based on the amount of magnesium halide Titanate/mol magnesium halide, preferably 0.05-0.8 mol titanate/mol magnesium halide. The use of titanate compounds in the present invention helps to improve the bulk density of the polymer and reduce the content of fine powder; and the amount of titanate compounds should be strictly controlled.

Add the alkylaluminum chloride compound to the above magnesium compound solution, which can be added dropwise or all at once. The method of dropwise addition is preferred in the present invention. The dropwise addition time is 0.5-1 hour. After the addition is completed, the temperature is raised to 50-100°C and stirred. After reacting for 1-4 hours, a suspension with granular precipitate was obtained. Cool to room temperature and set aside. The dosage of the alkylaluminum chloride compound is based on the amount of alcohol added, and is 0.3-1.0 mol of alkylaluminum chloride/mol of alcohol, preferably 0.5-0.8 mol of alkylaluminum chloride/mol of alcohol.

At room temperature, the titanium compound is in contact with the suspension, and a certain amount of hydrocarbon solvent can be added in order to mix uniformly. The temperature is raised to 40-70° C., at this temperature, the reaction is stirred for 2-4 hours, and then the temperature is continued to be evaporated and dried to obtain the main component of the catalyst in powder form. The amount of titanium compound used is based on the amount of magnesium halide, and is 0.25-2.0 mol titanium compound/mol magnesium halide, preferably 0.3-1.0 mol titanium compound/mol magnesium halide.

When the titanium compound is in contact with the suspension, an electron donor can be added to participate in the reaction. The amount of the electron donor is based on the amount of magnesium halide, which is 0.1-0.8mol electron donor/mol magnesium halide, preferably 0.2-0.6mol electron donor /mol magnesium halide.

The main catalyst component and the co-catalyst are contacted and reacted according to the molar ratio of Ti in the main catalyst component to Al in the co-catalyst is 1: (30-300).

The main component of the catalyst obtained by the above preparation method can be directly contacted with the co-catalyst for the homopolymerization or copolymerization of ethylene. Comonomers that can be used are aliphatic alpha-olefins having 3 to 8 carbon atoms, including propylene, butene-1, hexene-1, 4-methylpentene-1, heptene-1, octene -1, the preferred α-olefins are butene-1 and hexene-1.

The catalyst of the invention can be used in the slurry polymerization process to produce ultra-high molecular weight polyethylene, the polymerization temperature is 50-100°C, preferably 55-80°C, and the polymerization pressure is 0.5-1.0Mpa.

Compared with the prior art, the ultra-high molecular weight polyethylene catalyst of the present invention has the following advantages:

1. The ultra-high molecular weight polyethylene catalyst of the present invention has high activity. When it is polymerized at 0.5Mpa and 65°C for 4 hours, the polymerization activity of the catalyst can reach more than 20,000 grams of polyethylene/gram of catalyst;

2. Titanate compounds are used in the preparation process of the main component of the catalyst, and ultra-high molecular weight polyethylene with a bulk density in the range of 0.36-0.4g/ ^cm3 can be obtained;

3. The catalyst of the present invention can be directly applied to polymerization without pre-polymerization;

4. The catalyst preparation method of the present invention is simple and feasible, and has a good working environment.

The analysis of the main components of the catalyst and the main performance test of the polyethylene product in the examples of this description are carried out by the following methods:

The bulk density is determined according to GB1636-1979;

Determination of viscosity-average molecular weight First, measure the intrinsic viscosity of the polymer according to GB1841-1980. The relationship between [η] and viscosity-average molecular weight M _η is [η]=K M _η ^α , K and α are constants, K=6.67*10 ² , α=0.67, from which the viscosity average molecular weight M _η can be calculated.

Detailed ways

The present invention is further illustrated through the detailed description of the specific examples of the present invention below, but the examples are not meant to limit the present invention.

Example 1:

In a 250ml four-neck flask equipped with a heating system and a stirring device and a condensing system, and purged with nitrogen, add 4.3 grams of anhydrous magnesium chloride and 80 milliliters of hexane, stir well, and measure 28 milliliters of 2-ethyl Add 0.8 ml of hexanol and n-butyl titanate dropwise into the flask, then raise the temperature to 65°C, keep the reaction at this temperature for 2 hours, cool to room temperature, add 20 ml of diethylaluminum chloride, and raise the temperature to 60°C , kept reacting at this temperature for 1.5 hours, cooled to room temperature, obtained a suspension of particle precipitates, washed with hexane solvent, then added 2.0 milliliters of diphenyl ether, 2 milliliters of titanium tetrachloride, and heated to 60 ℃, keep the reaction at this temperature for 3 hours, then continue to raise the temperature, and heat and dry under nitrogen purging to obtain a powdery catalyst main component with good fluidity.

Polymerization:

After fully cleaning the 2 liter stainless steel reactor with high-purity nitrogen, add 1200 milliliters of dried industrial hexane, catalyst main components and cocatalyst triethylaluminum in the reactor, and control Al:Ti=200. The temperature was raised to 50°C, and ethylene was added to maintain the total reaction pressure at 0.5 MPa. Continue to raise the temperature to 65°C and keep the reaction at this temperature for 4 hours. After polymerization, the ethylene feed was stopped and the reactor was rapidly cooled and vented. The polymer slurry is recovered and the polyethylene powder is separated from the hexane. The result data of catalyst polymerization evaluation are shown in Table 1, and the screening data of polymerization products are shown in Table 2.

Example 2:

The diphenyl ether was replaced with diphenyldimethoxysilane, and the consumption was 2.5 milliliters, and the rest were the same as in Example 1.

Polymerization is the same as in Example 1. The result data of catalyst polymerization evaluation are shown in Table 1, and the screening data of polymerization products are shown in Table 2.

Example 3:

The amount of butyl titanate was adjusted to 2.3 milliliters, and the rest were the same as in Example 1.

Polymerization is the same as in Example 1. The result data of catalyst polymerization evaluation are shown in Table 1, and the screening data of polymerization products are shown in Table 2.

Example 4:

The amount of butyl titanate was adjusted to 4.6 milliliters, and the rest were the same as in Example 1.

Polymerization is the same as in Example 1. The result data of catalyst polymerization evaluation are shown in Table 1, and the screening data of polymerization products are shown in Table 2.

Comparative Example 1:

No butyl titanate was added, and the rest were the same as in Example 1.

Polymerization is the same as in Example 1. The result data of catalyst polymerization evaluation are shown in Table 1, and the screening data of polymerization products are shown in Table 2.

Comparative example 2:

The amount of butyl titanate was adjusted to 0.3 ml, and the rest were the same as in Example 1.

Polymerization is the same as in Example 1. The result data of catalyst polymerization evaluation are shown in Table 1, and the screening data of polymerization products are shown in Table 2.

Comparative example 3:

The consumption of butyl titanate was adjusted to 18 milliliters, and the others were the same as in Example 1.

Polymerization is the same as in Example 1. The result data of catalyst polymerization evaluation are shown in Table 1, and the screening data of polymerization products are shown in Table 2.

Table 1: Example number Ti(OBu) ₄ /MgCl ₂ mol/mol Activity (g polyethylene/g catalyst) Bulk density (g/ ^cm3 ) Viscosity average molecular weight (10,000) Example 1 0.05 20775 0.38 507 Example 2 0.05 23276 0.40 549 Example 3 0.42 21364 0.37 491 Example 4 0.7 26167 0.38 480 Comparative Example 1 0 8500 0.32 501 Comparative Example 2 0.02 7531 0.29 472 Comparative Example 3 1.2 7426 0.27 494

Table 2 Example number ＜20 mesh (wt%) 20～40 mesh (wt%) 40～75 mesh (wt%) 75～120 mesh (wt%) 120～200 mesh (wt%) >200 mesh (wt%) Example 1 5.6 10.3 49.8 21.3 12.7 0.3 Example 2 7.5 9.2 50.4 19.8 12.9 0.2 Example 3 7.3 7.8 52.2 23.3 9.2 0.2 Example 4 6.5 10.1 45.9 28.4 9.0 0.1 Comparative Example 1 8.9 15.3 44.3 12.4 15.6 3.5 Comparative Example 2 4.1 14.2 48.2 14.1 16.2 3.2 Comparative Example 3 5.7 13.5 47.4 20.4 9.0 4.0

Claims (11)

1, a kind of extra high-molecular polythene catalyst, this catalyzer comprises body of catalyst component and promotor, and wherein the preparation of body of catalyst component obtains by following steps:

(1) halogenated magnesium compound and alcohol compound, the reaction of titanate ester compound form magnesium compound solution,

(2) magnesium compound solution and chlorination alkylaluminium cpd reaction obtains an intermediate product,

(3) intermediate product reacts with titanium compound, electron donor again.

2, extra high-molecular polythene catalyst according to claim 1 is characterized in that described halogenated magnesium compound is a magnesium chloride.

3, extra high-molecular polythene catalyst according to claim 1 is characterized in that described alcohol is 2-Ethylhexyl Alcohol.

4, extra high-molecular polythene catalyst according to claim 1 is characterized in that described chlorination alkylaluminium cpd is an aluminium diethyl monochloride.

5, extra high-molecular polythene catalyst according to claim 1 is characterized in that described titanate ester is a tetrabutyl titanate.

6, extra high-molecular polythene catalyst according to claim 1, it is characterized in that described electron donor is ethers, ester class and silane compound, wherein ethers comprises phenyl ether, cresyl ether or ethylbenzene ether, the ester class comprises benzoates, phosphoric acid ester, and benzoates comprises ethyl benzoate, terephthalic acid two isobutyls, diisobutyl phthalate, di-n-butyl terephthalate, n-butyl phthalate, methyl benzoate, 2 hydroxybenzoic acid ethyl ester, 3-nipagin A or 4-methyl hydroxybenzoate; Phosphoric acid ester comprises tributyl phosphate or triphenyl phosphite; Silane compound comprises dimethyldimethoxysil,ne, dimethoxydiphenylsilane, phenylbenzene diethoxy silane or dimethyldiethoxysilane.

7, extra high-molecular polythene catalyst according to claim 6 is characterized in that described electron donor is phenyl ether or dimethoxydiphenylsilane.

8, extra high-molecular polythene catalyst according to claim 1 is characterized in that described titanium compound is a titanium tetrachloride.

9, a kind of preparation method of extra high-molecular polythene catalyst comprises following preparation process:

(1) magnesium halide and alcohol compound, titanate ester compound contact reacts in hydrocarbon solvent prepare magnesium compound solution, the add-on of titanate ester and alcohol compound is in the consumption of magnesium halide, be 2～10mol alcohol/1mol magnesium halide, 0.03～0.5mol titanate ester/1mol magnesium halide;

(2) adding chlorination alkylaluminium cpd, reaction obtain a suspension in above-mentioned magnesium compound solution, and the consumption of chlorination alkylaluminium cpd is 0.3～1.0mol chlorination aluminum alkyls/1mol alcohol in the add-on of alcohol;

(3) titanium compound, electron donor and above-mentioned suspension contact reacts, obtain the body of catalyst component, the consumption of titanium compound and the consumption of electron donor are all in the consumption of magnesium halide, be respectively 0.25～2.0mol titanium compound/1mol magnesium halide, 0.1～0.8mol electron donor/1mol magnesium halide;

(4) body of catalyst component and promotor contact reacts, wherein in the body of catalyst component in Ti and the promotor mol ratio of Al be 1: (30～300).

10, the preparation method of extra high-molecular polythene catalyst according to claim 9 is characterized in that the consumption of the add-on of alcohol in magnesium halide, is 3～8mol alcohol/1mol magnesium halide; The consumption of chlorination alkylaluminium cpd is 0.5～0.8mol chlorination aluminum alkyls/1mol alcohol in the add-on of alcohol; The consumption of titanate ester compound is 0.05～0.8mol titanate ester/1mol magnesium halide in the consumption of magnesium halide; The consumption of titanium compound is 0.25～2.0mol titanium compound/1mol magnesium halide in the consumption of magnesium halide.

11, the purposes of the described extra high-molecular polythene catalyst of claim 1 is characterized in that described catalyzer is applied to the homopolymerization or the copolymerization of ethene.