Ultra-high molecular weight, ultra-fine particle size polyethylene, preparation method therefor and use thereof

Abstract

An ultra-high molecular weight, ultra-fine particle size polyethylene has a viscosity average molecular weight (Mv) greater than 1×10.sup.6. The polyethylene is spherical or are sphere-like particles having a mean particle size of 10-100 μm, having a standard deviation of 2-15 μm and a bulk density of 0.1-0.3 g/mL. Using the polyethylene as a basic polyethylene, a grafted polyethylene can be obtained by means of a solid-phase grafting method; and a glass fiber-reinforced polyethylene composition comprising the polyethylene and glass fibers, and a sheet or pipe prepared therefrom; a solubilized ultra-high molecular weight, ultra-fine particle size polyethylene; and a fiber and a film prepared from the solubilized ultra-high molecular weight, ultra-fine particle size polyethylene may also be obtained. The method has simple steps, is easy to control, has a relatively low cost and a high repeatability, and can realize industrialisation.

Claims

1. A method for preparing an ultra-high molecular weight, ultra-fine particle size polyethylene powder, comprising: carrying out ethylene polymerization in presence of a catalyst at a polymerization temperature of −20° C. to 100° C., wherein, in the ethylene, a content of carbon monoxide is not higher than 5 ppm, a content of carbon dioxide is not higher than 15 ppm, and a content of conjugated diene is not higher than 10 ppm, wherein the catalyst is prepared by a method comprising steps of: (a) mixing magnesium halide, an alcohol compound, a titanate compound, a first portion of an internal electron donor compound, and a solvent to prepare a mixture I; (b) adding the mixture I into a reactor, preheating to −30° C.-30° C., and adding a first portion of a titanium compound to form a reaction mixture; or adding the first portion of the titanium compound into the reactor, preheating to −30° C.-30° C., and adding the mixture I to form the reaction mixture; (c) raising the temperature of the reaction mixture and maintaining the temperature at 90° C.-130° C. for 0.5-3 hours, adding a second portion of the internal electron donor compound to the reaction mixture, and continuously reacting; (d) filtering the reaction mixture to remove liquid, adding a second portion of the titanium compound, and continuously reacting; and (e) obtaining the catalyst after post-treatment.

2. The method according to claim 1, wherein the polyethylene powder has a viscosity average molecular weight (Mv) of greater than 1×10.sup.6, a mean particle size of 10-100 μm, a standard deviation of 2 μm-15 μm, and a bulk density of 0.1 g/mL-0.3 g/mL, and a particle size distribution that is substantially a normal distribution.

3. A method for preparing an ultra-high molecular weight, ultra-fine particle size grafted polyethylene, comprising: preparing a polyethylene powder according to the method of claim 1; mixing the polyethylene powder, a grafting monomer, an initiator and an interface agent to form a mixture; heating the mixture to carry out a solid-phase grafting reaction to form the grafted polyethylene.

4. The method according to claim 3, wherein the solid-phase grafting reaction is carried out at a temperature of 60-120° C. for 0.5-5 hours, wherein the grafting monomer is a siloxane-based compound or a vinyl-based unsaturated compound, and said initiator is an azo initiator or a peroxide initiator.

5. The method according to claim 3, wherein an effective grafting rate of the grafting monomer is ≥0.5%, the polyethylene powder is spherical or substantially spherical particles having a mean particle size of 10 μm-100 μm, a standard deviation of 2 μm-15 μm and, a bulk density of 0.1 g/mL-0.3 g/mL, and a viscosity average molecular weight (Mv) of greater than 1×10.sup.6.

6. The method according to claim 5, wherein, the effective grafting rate is 1.0-3.0%, the mean particle size of said polyethylene powder is 20 μm-80 μm, the standard deviation of said polyethylene powder is 5 μm-15 μm, a water contact angle of said grafted polyethylene is 80°-88°, the bulk density of said polyethylene is 0.15 g/mL-0.25 g/mL, the viscosity average molecular weight (Mv) of said polyethylene is greater than or equal to 1.5×10.sup.6, and said polyethylene is an ethylene homopolymer having a molecular weight distribution (Mw/Mn) of 2-15.

7. A method for preparing a glass-fiber enforced polyethylene sheet, comprising: preparing a polyethylene powder according to the method of claim 1; mixing the polyethylene powder with and glass fibers; and extruding the mixture through a sheet die.

8. A method for preparing a glass-fiber enforced polyethylene pipe, comprising: preparing a polyethylene powder according to the method of claim 1; mixing the polyethylene powder and glass fibers; and extruding the mixture through a pipe mold.

9. The method according to claim 2, wherein the polymerization temperature is 30° C.-80° C.

10. The method according to claim 2, wherein the polymerization temperature is 50° C.-80° C.

11. An ultra-high molecular weight, ultra-fine particle size polyethylene powder prepared by the method according to claim 1, having a viscosity average molecular weight (Mv) of greater than 1×10.sup.6, a standard deviation of 2 μm-15 μm, and a bulk density of 0.1 g/mL-0.3 g/mL, having a particle size distribution that is substantially a normal distribution, and a mean particle size of 20 μm-80 μm.

12. The ultra-high molecular weight, ultra-fine particle size polyethylene powder according to claim 11, wherein the mean particle size of said polyethylene powder is 50 μm-80 μm.

13. The method according to claim 4, wherein an amount of said grafting monomer is 0.2-15 wt % by weight of the polyethylene powder and an amount of said initiator is 0.1-10 wt % by weight of the polyethylene powder, wherein the vinyl-based unsaturated compound is selected from a styrene-based compound, a vinyl-based unsaturated organic acid, a vinyl-based unsaturated organic ester, a vinyl-based unsaturated organic acid anhydride, acrylic acid (AA), methacrylic acid (MAA), methyl acrylate (MA), methyl methacrylate (MMA), ethyl acrylate (EA), ethyl methacrylate (MEA), butyl acrylate (BA), butyl methacrylate (BMA), maleic anhydride (MAH), maleic acid, styrene (St), and pentaerythritol triacrylate (PETA), and mixtures thereof, the siloxane-based compound is selected from vinyltrimethylsilane, vinyltriethylsilane, divinyldimethylsilane, (triethylsilyl)acetylene, allyltrimethylsilane, and mixtures thereof, and said initiator is an azo initiator or a peroxide initiator.

14. An ultra-high molecular weight, ultra-fine particle size grafted polyethylene, comprising the polyethylene powder prepared according to the method of claim 1, and a grafting monomer grafted on the polyethylene powder, wherein the grafting monomer is a siloxane-based compound or a vinyl-based unsaturated compound, and an amount of said grafting monomer is 0.2-15 wt % by weight of the polyethylene powder.

15. An ultra-high molecular weight, ultra-fine particle size grafted polyethylene of claim 14, wherein the vinyl-based unsaturated compound is selected from a styrene-based compound, a vinyl-based unsaturated organic acid, a vinyl-based unsaturated organic ester, a vinyl-based unsaturated organic acid anhydride, acrylic acid (AA), methacrylic acid (MAA), methyl acrylate (MA), methyl methacrylate (MMA), ethyl acrylate (EA), ethyl methacrylate (MEA), butyl acrylate (BA), butyl methacrylate (BMA), maleic anhydride (MAH), maleic acid, styrene (St), and pentaerythritol triacrylate (PETA), and mixtures thereof, the siloxane-based compound is selected from vinyltrimethylsilane, vinyltriethylsilane, divinyldimethylsilane, (triethylsilyl)acetylene, allyltrimethylsilane, and mixtures thereof, and said initiator is an azo initiator or a peroxide initiator.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1 is a scanning electron micrograph of the polyethylene particles of Example 1.3.

(2) FIG. 2 is an IR spectrum of the maleic anhydride grafted polyethylene of Example 2.1.

EXAMPLES

(3) Preparation Method of Catalyst

(4) The catalyst used in the preparation method of the present invention can be prepared by the method disclosed in an already-filed patent application by the applicant (Application No. 201510271254.1), which is incorporated by reference in its entirety.

(5) As described above, in the preparation method of the ultra-high molecular weight, ultra-fine particle size polyethylene powder and the solubilized ultra-high molecular weight, ultra-fine particle size polyethylene in the present invention, the catalyst used is prepared by a method comprising the following steps:

(6) (a) mixing a magnesium halide, an alcohol compound, an auxiliary agent, a part of internal electron donor compound and a solvent to prepare mixture I;

(7) (b) adding the aforementioned mixture I into a reactor, preheating to −30° C.-30° C., adding an titanium compound dropwise; or, adding the titanium compound into the reactor, preheating to −30° C.-30° C., adding the aforementioned mixture I dropwise;

(8) (c) after the completion of the dropwise addition, raising the temperature of the reaction system to 90° C.-130° C. for 0.5-3 hours, adding the rest internal electron donor compound, and continuously reacting;

(9) (d) filtering off the liquid of the reaction system, adding the rest titanium compound, and continuously reacting;

(10) (e) after the completion of the reaction, obtaining the catalyst by using post-treatment;

(11) According to the present invention, the step (b) is replaced by the following step (b′):

(12) (b′) preparing mixture II containing nanoparticles, a dispersant and a solvent; adding the aforementioned mixture I and mixture II into the reactor to obtain a mixture, preheating to −30° C. to 30° C., adding an titanium compound dropwise; or,

(13) adding the titanium compound into the reactor, preheating to −30° C. to 30° C., and adding the mixture of the aforementioned mixture I and mixture II dropwise.

(14) In the present invention, mixture I is preferably prepared by the following method: mixing a magnesium halide and an alcohol compound in an organic solvent, heating and maintaining the temperature, and then adding an auxiliary agent and a part of the internal electron donor compound to obtain a stable homogeneous mixture I after the reaction at a certain temperature.

(15) The alcohol compound is one or more selected from a C.sub.1-C.sub.15 fatty alcohol compound, a C.sub.3-C.sub.15 cycloalkanol compound, and a C.sub.6-C.sub.15 aromatic alcohol compound, preferably one or more of methanol, ethanol, glycol, n-propanol, isopropanol, 1,3-propanediol, butanol, isobutanol, hexanol, heptanol, n-octanol, isooctanol, nonanol, decanol, sorbitol, cyclohexanol or benzyl alcohol, more preferably ethanol, butanol, hexanol and isooctanol.

(16) The internal electron donor is at least one of a monoester, a diester, a monoether, and a diether compound, preferably a diester or a diether. Specifically it is selected from the group consisting of aromatic carboxylic acid diester, 1,3-diether, malonic ester, succinate, glutarate, glycol ester, such as diisobutyl phthalate, di-n-butyl phthalate, 1,3-diether compound, 9,9-di(methoxymethyl)fluorene, di-n-butyl 2-isopropylmalonate, diethyl 2-decylmalonate, diethyl 2-methyl-2-isopropylmalonate, diisobutyl diisopropylsuccinate, diethyl 2,3-diisopropylsuccinate, β-substituted glutarates, 1,3-diol ester, etc. The aforementioned internal electron donors are disclosed in the following patents or applications: CN1453298, CN1690039, EP1840138, CN101423566, CN101423570, CN101423571, CN101423572, CN1986576, CN1986576, CN101125898, CN1891722, WO2007147864, CN1831017, CN101560273, EP 2029637, EP2029642, CN1330086, CN1463990, CN1397568, CN1528793, CN1732671, CN1563112, CN1034548, CN1047302, CN1091748, CN1109067, CN94103454, CN1199056, EP03614941990, EP03614931990, WO002617, etc.

(17) The solvent is at least one selected from the group consisting of a linear alkane in the C.sub.5-C.sub.20 range, a branched alkane in the C.sub.5-C.sub.20 range, an aromatic hydrocarbon in the C.sub.6-C.sub.20 range or their halogenated hydrocarbons, preferably at least one of toluene, chlorobenzene, dichlorobenzene or decane.

(18) In the present invention, magnesium halide, which serves as a carrier in the preparation of a catalyst for directly obtaining submicron-sized polyolefin particles, is one of the components of the conventional Ziegler-Natta catalyst, and the catalyst is prepared in a suitable shape, size and mechanical strength. Meanwhile, the active components can disperse on the carrier surface to obtain a higher specific surface area, thus improving the catalytic efficiency of the active components per unit mass. Furthermore, an alcohol compound is used to dissolve the carrier, i.e. magnesium halide. In the preparation of the mixture I, the temperature of the mixed solution is preferably 110-130° C., more preferably 130° C. The isothermal holding time is preferably 1-3 hours, more preferably 2-3 hours. The reaction time, after adding auxiliaries and so on, is 0.5-2 hours, more preferably 1 hour. Therefore, magnesium halide is dissolved by the alcohol compound at a high temperature to obtain the mixture I.

(19) According to the present invention, the mixture II is preferably prepared by the following method: adding nanoparticles, a dispersant and a solvent to a reaction vessel and sonicating to obtain a homogeneous mixture II. The nanoparticles are preferably at least one selected from nano silicon dioxide, nano titanium dioxide, nano zirconium dioxide, nano nickel oxide, nano magnesium chloride or nano carbon spheres, more preferably nano silicon dioxide, nano titanium dioxide. The particle size of the nanoparticles is preferably 1-80 nm, more preferably 10-50 nm. The added amount of the nanoparticles is preferably 0%-200%, more preferably 0%-20%, relative to the added amount of the magnesium halide. The time of ultrasound treatment is preferably 2 hours. In the present invention, the nanoparticles are added as seed crystals in order to accelerate the carrier formation and reduce the catalyst particle size; the dispersant and solvent, including the ultrasound treatment, are all used to assist nanoparticle dispersion, thus promoting each nanoparticle to be as a seed crystal.

(20) According to the present invention, in the mixture II in step (b′), the nanoparticles are at least one selected from nano silicon dioxide, nano titanium dioxide, nano zirconium dioxide, nano nickel oxide, nano magnesium chloride or nano carbon spheres.

(21) Preferably, the particle size of the nanoparticles is 1-80 nm, preferably 2-60 nm, more preferably 3-50 nm.

(22) The added amount of the nanoparticles is larger than 0% and less than or equal to 200%, preferably in a range between larger than 0% and less than or equal to 20%, relative to the added amount of the magnesium halide.

(23) In the present invention, in the mixture II in step (b′), the solvent is at least one selected from the group consisting of a linear alkane in the C.sub.5-C.sub.20 range, a branched alkane in the C.sub.5-C.sub.20 range, an aromatic hydrocarbon in the C.sub.6-C.sub.20 range or their halogenated hydrocarbons.

(24) The dispersant is selected from the group consisting of titanium tetrachloride, silicon tetrachloride or a mixture thereof.

(25) In step (a), the mixing with heating and stirring is carried out to obtain a homogenously stable transparent mixture I.

(26) In step (b′), ultrasonic dispersion treatment is carried out during preparing mixture II.

(27) In step (b) or (b′), the dropwise addition is a slow dropwise addition.

(28) In step (b) or (b′), the preheating temperature is preferably −20° C. to 30° C., more preferably −20° C. to 20° C.

(29) The reaction time in step (c) is 1-5 hours, preferably 2-3 hours.

(30) The continue reaction time in step (d) is 1-5 hours, preferably 2-3 hours.

(31) The post-treatment in step (e) can be that the obtained product is washed with hexane and then dried; wherein the number of washings is 1-10 times, preferably 3-6 times.

(32) In step (a), magnesium halide is at least one selected from the group consisting of magnesium chloride, magnesium bromide, and magnesium iodide.

(33) In step (a), the auxiliary agent is a titanate compound.

(34) In step (b) or (b′), the formula of the titanium compound is as shown in Formula I:
Ti(R).sub.nX.sub.(4-n)  Formula I

(35) wherein, R is a branched or linear chain C.sub.1-C.sub.12 alkyl group, X is halogen, and n is 0, 1, 2 or 3.

(36) In step (d), preferably, the reaction system is heated to 90° C. to 130° C. over a period of 40 minutes to 3 hours, more preferably, the reaction system is heated to 100° C. to 120° C. over a period of 40 minutes to 2 hours.

(37) It can be seen from the above resolution that the preparation method of the Ziegler-Natta catalyst according to the present invention is simple-processing and is easy to industrialize. Moreover, when ethylene is polymerized, the Ziegler-Natta catalyst prepared by the present invention can be used to produce polyethylene particles having a mean particle size of 10-100 μm, high sphericity, a narrow particle size distribution, and a low bulk density (0.1-0.3 g/mL). It is found that the obtained polyethylene particles prepared by using the catalyst prepared by the present invention have particle sizes reduced by 20-30 times, a significantly narrower particle size distribution and a bulk density as low as 0.1 g/mL compared to other polyethylene.

(38) Preparation Method of an Ultra-High Molecular Weight, Ultra-Fine Particle Size Polyethylene Powder;

(39) As described above, the present invention provides a method for preparing an ultra-high molecular weight, ultra-fine particle size polyethylene powder, which comprises the following steps: under the action of a catalyst, carrying out ethylene polymerization, wherein the polymerization temperature is −20 to 100° C.; in ethylene, a content of carbon monoxide is less than 5 ppm, a content of carbon dioxide is less than 15 ppm, and a content of conjugated diene is less than 10 ppm;

(40) the catalyst is prepared by the above-mentioned method for preparing the catalyst.

(41) The present invention found that the simply controlled the preparation method of the catalyst can indeed achieve good control over the particle size of the powder, but the molecular weight of the prepared polyethylene is not high. In order to achieve particle size control while increasing the molecular weight of the polymer, the inventors have made many attempts. It is found that controlling the temperature of the polymerization reaction and the purity of the monomer is a simple and effective method, and does not affect the effective control over the particle size of the polymer, and even is helpful to prepare the polymer with a narrower particle size distribution and a lower bulk density range.

(42) It is found that the polymerization temperature is controlled at −20 to 100° C., and purity control of ethylene is that a content of carbon monoxide is less than 5 ppm, a content of carbon dioxide is less than 15 ppm, and a content of conjugated diene is less than 10 ppm, which can achieve particle size control while preparing ultra-high molecular weight polyethylene. Preferably, the polymerization temperature is 30-80° C., more preferably 50-80° C.

(43) Ultra-High Molecular Weight, Ultra-Fine Particle Size Polyethylene Powder

(44) As described above, the present invention provides an ultra-high molecular weight, ultra-fine particle size polyethylene powder.

(45) The ultra-high molecular weight polyethylene having the particle sizes and the bulk density is particularly suitable for graft modification, for one thing, it greatly expands the scope of the polyethylene modification, for another, the processing performance of the polymer is remarkably improved to be suitable for the preparation of a wider range of products. Thus, the application field of the polymer is effectively expanded.

(46) The ultra-high molecular weight ultra-fine particle size polyethylene powder of the present invention also exhibits the following excellent properties, including: firstly, excellent wear resistance, that the wear resistance index is several times higher than those of metals such as carbon steel and copper; secondly, high impact strength, due to the ultra-high molecular weight, the ultra-long molecular chains; moreover, higher chemical corrosion resistance than that of common polyolefins; finally, wider operating temperature range, which can maintain good toughness and high strength at lower or higher temperatures.

(47) Solid-Phase Grafting Method for Preparing a Grafted Polyethylene with Relatively High Grafting Rates

(48) As described above, the present invention provides a method for preparing an ultra-high molecular weight, ultra-fine particle size grafted polyethylene by a solid-phase grafting method.

(49) In a preferred embodiment of the present invention, the grafted polyethylene was prepared as follows:

(50) in the container, adding the polyethylene powder with a viscosity average molecular weight (Mv) of greater than 1×10.sup.6, a mean particle size of 10 μm-100 μm (preferably 20 μm-80 μm, more preferably 50 μm-80 μm), a standard deviation of 2 μm-15 μm (preferably 5 μm-15 μm, more preferably 6 μm-12 μm, still more preferably 8 μm-10 μm), and a bulk density of 0.1 g/mL-0.3 g/mL (preferably in the range of 0.15 g/mL-0.25 g/mL);

(51) adding an azo initiator or a peroxide initiator (e.g. benzoyl peroxide) in an amount of 0.1-10 wt % by weight of the polyethylene powder, preferably 2-9 wt %, more preferably 3-8 wt %;

(52) adding a grafting monomer selected from a siloxane-based compound or a vinyl-based unsaturated compound, of which the vinyl-based unsaturated compound is, for example, a styrene-based compound, a vinyl-based unsaturated organic acid, a vinyl-based unsaturated organic ester, a vinyl-based unsaturated organic acid anhydride, or a mixture thereof, more preferably one or more selected from acrylic acid (AA), maleic anhydride (MAH), methyl methacrylate (MMA), styrene (St); a siloxane-based compound is, for example, vinyltrimethylsilane, vinyltriethylsilane, divinyldimethylsilane, (triethylsilyl)acetylene, allyltrimethylsilane, etc., preferably one or two selected from vinyltrimethylsilane and vinyltriethylsilane; the added amount of grafting monomer is in an amount of 0.2-15 wt % by weight of the polyethylene powder, preferably 0.5-12 wt %, more preferably 1-9 wt %;

(53) adding an interface agent, preferably one or more selected from among benzene, toluene, xylene, tetrahydrofuran, diethyl ether, acetone, hexane, heptanes, more preferably one or more selected from among toluene, xylene, tetrahydrofuran, diethyl ether, acetone. For example, it is xylene or a mixture of xylene and tetrahydrofuran; the added amount of interface agent is in an amount of 0.1-30 wt % by weight of the polyethylene powder, preferably 10-25 wt %.

(54) After the completion of addition of the raw materials, the high-speed mechanical stirring was carried out, and the stirring time was related to the efficiency of the stirring paddle. The aims of the stirring were to homogenously mix the reactants, to make the grafting reaction more completely and to minimize self-polymerization of the grafting monomers. Therefore, the stirring time was uncertain, and usually 0.5-5 hours, preferably 1-5 hours, more preferably 3-5 hours. The solid-phase grafting reaction was carried out by heating, and the grafting reaction conditions were at 60 to 120° C. for 0.5-5 hours, preferably at 70 to 110° C. for 0.5-3.5 hours, more preferably at 85 to 110° C. for 2-3 hours. After the completion of the reaction, the product was a grafted polyethylene having a high grafting rate.

(55) Preparation Method of a Solubilized Ultra-High Molecular Weight, Ultra-Fine Particle Size Polyethylene

(56) As described above, the present invention provides a method for preparing a solubilized ultra-high molecular weight, ultra-fine particle size polyethylene.

(57) The present invention found that the simply controlled the preparation method of the catalyst can indeed achieve good control over the particle size of the polyethylene, but the molecular weight of the prepared polyethylene is not high. In order to achieve particle size control while increasing the molecular weight of the polymer, the inventors have made many attempts. It is found that controlling the temperature of the polymerization reaction and the purity of the monomer is a simple and effective method, and does not affect the effective control over the particle size of the polymer, and even is helpful to prepare the polymer with a narrower particle size distribution and a lower bulk density range.

(58) It is found that the polymerization temperature is controlled at −20 to 100° C., and purity control of ethylene is that a content of carbon monoxide is less than 5 ppm, a content of carbon dioxide is less than 15 ppm, and a content of conjugated diene is less than 10 ppm, which can achieve particle size control while preparing ultra-high molecular weight polyethylene. Preferably, the polymerization temperature is 0 to 90° C., preferably 10 to 85° C., still preferably 30 to 80° C., more preferably 50 to 80° C.

(59) In addition, in order to further improve the processability of the ultra-high molecular weight, ultra-fine particle size polyethylene, a solubilization method is further introduced in the present invention, that is, the present invention introduces a dispersion medium or a dispersion medium and a solvent in the process of preparing polyethylene. The presence of these small molecules enables the crystal zone size of the obtained polyethylene to greatly be reduced, molecular chains to more easily move and heats to be more easily transferred in the subsequent dissolution or melt processing of products, so that the obtained polyethylene can be rapidly dissolved or melted at a lower temperature, thereby shortening the process. Furthermore, it can also significantly reduce the polyethylene degradation by decreasing the dissolution or melting temperature, which is very critical for ensuring its molecular weight and obtaining high performance polyethylene products.

(60) Solubilized Ultra-High Molecular Weight, Ultra-Fine Particle Size Polyethylene

(61) As described above, the present invention provides a solubilized ultra-high molecular weight, ultra-fine particle size polyethylene.

(62) The ultra-high molecular weight polyethylene having the particle sizes, the bulk density and solvent content is particularly suitable for graft modification, for one thing, it greatly expands the scope of the polyethylene modification, for another, the processing performance of the polymer is remarkably improved to be suitable for the preparation of a wider range of products. Thus, the application field of the polymer is effectively expanded.

(63) Meanwhile, the polyethylene of the present invention also exhibits the following excellent properties, including: 1) excellent wear resistance, that the wear resistance index is several times higher than those of metals such as carbon steel and copper; 2) high impact strength, due to the ultra-high molecular weight, the ultra-long molecular chains; 3) higher chemical corrosion resistance than that of common polyolefins; 4) wider operating temperature range, which can maintain good toughness and high strength at lower or higher temperatures; 5) low energy consumption and short process time in the process of postforming, film forming and fiber forming.

(64) Fiber and Preparation Method Thereof

(65) As described above, the present invention provides a fiber and a preparation method thereof.

(66) In a preferred embodiment of the present invention, in step (1), dissolving and mixing a mixture containing the solubilized ultra-high molecular weight, ultra-fine particle size polyethylene with a solvent to obtain a spinning solution or gel. In the present invention, the solvent is an organic solvent capable of dissolving the polyethylene, for example, decahydronaphthalene, white oil, etc. The content of the polymer in the spinning solution or gel is 3-20 wt %, preferably 5-15 wt %.

(67) In a preferred embodiment of the present invention, in step (2), the solution gel spinning method is taken as an example, which specifically comprises the following steps: mixing a solubilized ultra-high molecular weight, ultra-fine particle size polyethylene with a solvent to obtain a mixture; dissolving and extruding the mixture through a twin-screw extruder (preferably, the temperature of the dissolution extrusion is 120-270° C., preferably 150-240° C.) to obtain a spinning solution; directly extruding the spinning solution with a twin-screw extruder through a spinning assembly and a spinneret, and passing through a coagulation bath (for example, a cooling water bath; preferably, the water bath temperature is 0-15° C., preferably 2-10° C.) to obtain a gel fiber; the gel fiber being via the processes of gel wire drawing, solvent extraction, drying, first hot-box dry-hot drawing, second hot-box dry-hot drawing, heat setting, winding, etc., to obtain the fiber of the present invention. According to the present invention, the raw material also comprises an antioxidant in addition to the solubilized ultra-high molecular weight, ultra-fine particle size polyethylene. Preferably, the added amount of the antioxidant is 0.01-1 part by weight, still preferably 0.02-0.5 part by weight, per 100 parts by weight of the solubilized ultra-high molecular weight, ultra-fine particle size polyethylene. Specifically, the fiber is prepared from the solubilized ultra-high molecular weight, ultra-fine particle size polyethylene containing the antioxidant.

(68) In the present invention, the mixture comprises an antioxidant in addition to the polyethylene. Preferably, the added amount of the antioxidant is 0.01-1 part by weight, still preferably 0.02-0.5 part by weight, per 100 parts by weight of the polyethylene. Specifically, the mixture consists of the solubilized ultra-high molecular weight, ultra-fine particle size polyethylene and the antioxidant. The antioxidant is an antioxidant for polyethylene known in the art, non-limiting. The antioxidant is composed of a primary antioxidant and a secondary antioxidant, wherein the primary antioxidant is selected from hindered phenolic antioxidants, and the secondary antioxidant is selected from the group consisting of thiodipropionate or phosphite, etc. The hindered phenolic antioxidants are some sterically hindered phenolic compounds, which exhibit a remarkably improved resistance to thermal oxidation, and do not pollute the products. This type of antioxidant has many varieties, mainly including 2,6-di-tert-butyl-4-methylphenol, bis(3,5-di-tert-butyl-4-hydroxybenzyl) sulfide, pentaerythritol tetrakis(β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), etc. The thiodipropionate is a secondary antioxidant, which is often used together with a hindered phenolic antioxidant, and the effect is remarkable, for example, didodecyl thiodipropionate, ditetradecyl thiodipropionate or distearyl thiodipropionate. The phosphite is also a secondary antioxidant, mainly including trioctyl phosphite, tridecyl phosphite, tris(dodecanol) phosphite, and tris(hexadecanol) phosphite, etc.

(69) The fiber of the present invention has excellent mechanical properties and creep resistance, and also has a wider use temperature range. Specifically, the fiber of the present invention has the following properties: fineness (dtex) of 1.5-3.0, breaking strength of greater than or equal to 2.0-3.5 GPa, modulus of 95-220 GPa, elongation at break of 3.0-4.5%, creep value of less than or equal to 2% (e.g. 1.0%-2.0%), crystallinity of 95%, melting point of 130° C. to 140° C., use temperature range of −30° C. to 135° C.

(70) Film and Preparation Method Thereof

(71) As described above, the present invention provides a film and a preparation method thereof.

(72) In a preferred embodiment of the present invention, the melt-mixing in step (1) is achieved by a twin-screw extruder, which is well known and will not be described in detail herein. In the solution, the weight percent of the polyethylene is 20-50 wt %, preferably 30-40 wt %. The solvent for film formation is at least one selected from cyclohexane, n-hexane, n-heptane, nonane, decane, undecane, dodecane, benzene, toluene, xylene, dichlorobenzene, trichlorobenzene, 1,1,1-trichloroethane, white oil, liquid paraffin, kerosene, olefin mineral oil and decahydronaphthalene. Wherein, the temperature of the melt-mixing varies depending on the polymer and the solvent, and is generally in the range of 130-280° C.

(73) In a preferred embodiment of the present invention, step (2) is specifically that the solution of step (1) is extruded from a mold to form a molded body (such as a sheet) during supplying the solution to a mold through an extruder, and a polymer sheet is obtained after cooling by a cooling drum. The surface temperature of the cooling drum is set to 20-40° C., and the cooling rate of the molded body through the cooling drum is more than 20° C./s.

(74) In a preferred embodiment of the present invention, the biaxial stretching in step (3) is that stretching the polymer sheet of step (2) is performed in the transverse direction (width direction, TD) and the longitudinal direction (machine direction MD) according to a certain multiple (transverse stretching multiple and longitudinal stretching multiple) by a usual stretching machine method, a drum method, or a combination thereof. In the present invention, the preferable transverse stretching multiple and longitudinal stretching multiple are 4-5 times, respectively, and preferably, the transverse stretching multiple is the same as the longitudinal stretching multiple.

(75) Furthermore, the content of the polymer in the raw material is 3-20 wt %, preferably 5-15 wt %. Moreover, an antioxidant is added in the raw material. Preferably, the added amount of the antioxidant is 0.01-1 part by weight, still preferably 0.02-0.5 part by weight, per 100 parts by weight of the polyethylene. The antioxidant is an antioxidant for polyethylene known in the art. Non-limiting, the antioxidant is composed of a primary antioxidant and a secondary antioxidant, wherein the primary antioxidant is selected from hindered phenolic antioxidants, and the secondary antioxidant is selected from the group consisting of thiodipropionate or phosphite, etc. The hindered phenolic antioxidants are some sterically hindered phenolic compounds, which exhibit a remarkably improved resistance to thermal oxidation, and do not pollute the products. This type of antioxidant has many varieties, mainly including 2,6-di-tert-butyl-4-methylphenol, bis(3,5-di-tert-butyl-4-hydroxybenzyl) sulfide, pentaerythritol tetrakis(β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), etc. The thiodipropionate is a secondary antioxidant, which is often used together with a hindered phenolic antioxidant, and the effect is remarkable, for example, didodecyl thiodipropionate, ditetradecyl thiodipropionate or distearyl thiodipropionate. The phosphite is also a secondary antioxidant, mainly including trioctyl phosphite, tridecyl phosphite, tris(dodecanol) phosphite, and tris(hexadecanol) phosphite, etc.

(76) Determination of Properties and Parameters

(77) The properties of the sheets and pipes of the present invention are determined by measurement methods according to well-known standards.

(78) For example, creep resistance is determined in accordance with the Chinese National Standard GB11546-89 and ISO899-1981. Impact resistance is determined according to GB/T1043.1-2008. Bending strength and bending modulus are measured according to GB/T9341-2008. Tensile strength is measured according to GB/T1040-2006. Heat distortion temperature is measured according to GB/T1634.2-2004.

(79) Characterization methods of the grafted polyethylene of the present invention:

(80) IR characterization of the grafted polyethylene: take a small amount of sample and press into a film with a flat vulcanizer, and then record infrared spectra with a NICOLET 560-type FTIR.

(81) Water Contact Angle Measurement: take a small amount of sample and press into a film with a flat vulcanizer. Deposit a drop of distilled water on a sample stage in order to allow the sample film adhering tightly to the sample stage. Extract a 2 μL of deionized water with a micro-injector and inject on the sample film. Measure water contact angles after 10 seconds.

(82) Determination method of the effective grafting rate of grafted polyethylene: weigh 1 g of the dried and purified grafted sample accurately, place in a 250 mL flask, add 80 mL of xylene, and heat under reflux until dissolved. After cooling, add an excess amount of a 0.1 mol/L KOH-ethanol solution and heat the mixture under reflux for 2 h. After cooling, use phenolphthalein as an indicator and titrate with a 0.1 mol/L HCl-isopropanol solution. Record the added amount of alkali and the consumed amount of acid for neutralization, and calculate the effective grafting rate of a solid-phase grafting reaction product by the following equation.

(83) $G=\frac{c_1{V}_1-c_2{V}_2}{a\times m}\times M\times 100\%$

(84) Wherein: G is the effective grafting rate of the product; c.sub.1 is the concentration of a KOH-ethanol solution, mol/L; V.sub.1 is the volume of the KOH-ethanol solution added in excess, mL; c.sub.2 is the concentration of a HCl-isopropanol solution, mol/L; V.sub.2 is the volume of the HCl-isopropanol solution consumed for titration neutralization of alkali, mL; a is the functionality of the grafting monomer involved in the neutralization reaction; m is the mass of the purified sample, g; M is the relative molecular weight of the monomer.

(85) The properties of the fibers and the films of the present invention are determined by measurement methods according to well-known standards.

(86) For example, creep resistance is determined in accordance with the measurement method of the Chinese National Standard GB 11546-89 and ISO 899-1981.

(87) In order to make the object, technical schemes and advantages of the present invention clearer, the present invention is further described in detail hereinafter with reference to the specific embodiments and accompanying drawings. However, it is understood by those skilled in the art that the present invention is not limited to the drawings and the following embodiments.

Preparation Example 1 (Preparation of Catalyst)

(88) In the reactor completely purged with high purity nitrogen gas, 4.94 g of anhydrous magnesium chloride, 18.9 g of isooctanol, and 30 ml of decane were sequentially added, the temperature was raised to 130° C. with stirring, and maintained for 2 hours, and then 2.65 g of tetrabutyl titanate and 2.05 g of diisobutylphthalate was added, further reacted at 130° C. for 1 hour and finally cooled to room temperature to obtain a homogeneous transparent solution, i.e. mixture I.

(89) To the reactor, 200 ml of titanium tetrachloride was added and stirred, preheated to 0° C., and mixture I was added dropwise to titanium tetrachloride in about 2 hours. After the addition was complete, the temperature began to increase and increased to 110° C. in 2 hours. 1.23 g of an internal electron donor diisobutyl phthalate was added. After reacting at this temperature for 2 hours, the reaction liquid was removed, 200 ml of titanium tetrachloride was again added, and the reaction was carried out for 2 hours. Finally, the reaction liquid was removed, and the remaining solids were washed with hexane 10 times at 60° C., and dried to obtain a catalyst.

Example 1.1 Ethylene Slurry Polymerization

(90) Under the protection of high purity nitrogen, a 1 L high pressure reactor was dried and deoxidized. 150 mL of n-Hexane, 20 mg of the catalyst prepared as described in the above Preparation Example 1 and 12 ml of triethyl aluminum were sequentially added, and then ethylene gas was fed into the reactor to keep the reactor pressure at 0.7 MPa; wherein, in ethylene, the content of carbon monoxide was less than 5 ppm, the content of carbon dioxide was less than 15 ppm, and the content of conjugated diene was less than 10 ppm; the polymerization reaction started, the system temperature was maintained at 80° C., and the reaction time was 30 minutes. The catalyst activity and the properties of the polyethylene are shown in Table 1.

Example 1.2 Ethylene Slurry Polymerization

(91) Under the protection of high purity nitrogen, a 1 L high pressure reactor was dried and deoxidized. 150 mL of n-Hexane, 20 mg of the catalyst prepared as described in the above Preparation Example 1 and 12 ml of triethyl aluminum were sequentially added, and then ethylene gas was fed into the reactor to keep the reactor pressure at 0.7 MPa; wherein, in ethylene, the content of carbon monoxide was less than 5 ppm, the content of carbon dioxide was less than 15 ppm, and the content of conjugated diene was less than 10 ppm; the polymerization reaction started, the system temperature was maintained at 70° C., and the reaction time was 30 minutes. The catalyst activity and the properties of the polyethylene are shown in Table 1.

Example 1.3 Ethylene Slurry Polymerization

(92) Under the protection of high purity nitrogen, a 1 L high pressure reactor was dried and deoxidized. 150 mL of n-Hexane, 20 mg of the catalyst prepared as described in the above Preparation Example 1 and 12 ml of triethyl aluminum were sequentially added, and then ethylene gas was fed into the reactor to keep the reactor pressure at 0.7 MPa; wherein, in ethylene, the content of carbon monoxide was less than 5 ppm, the content of carbon dioxide was less than 15 ppm, and the content of conjugated diene was less than 10 ppm; the polymerization reaction started, the system temperature was maintained at 50° C., and the reaction time was 30 minutes. The catalyst activity and the properties of the polyethylene are shown in Table 1.

(93) FIG. 1 is a scanning electron microscopy image of the polyethylene prepared in Example 1.3. It can be seen from FIG. 1 that all of the polyethylene particles exhibit good sphericity, spherical or spheroidal, and have a uniform particle size distribution and smaller average particle diameter.

Comparative Example 1.1 Ethylene Bulk Polymerization

(94) Under the protection of high purity nitrogen, a 1 L high pressure reactor was dried and deoxidized. 150 mL of n-Hexane, 20 mg of the catalyst prepared as described above and 12 ml of triethyl aluminum were sequentially added, and then ethylene gas was fed into the reactor to keep the reactor pressure at 0.7 MPa; wherein, in ethylene, the content of carbon monoxide was more than 10 ppm, the content of carbon dioxide was more than 20 ppm, and the content of conjugated diene was more than 20 ppm; the polymerization reaction started, the system temperature was maintained at 110° C., and the reaction time was 30 minutes. The catalyst activity and the properties of the polyethylene are shown in Table 1.

(95) TABLE-US-00001 TABLE 1 The catalyst activity of the Ziegler-Natta catalyst prepared in Preparation Example 1 and the properties of the polyethylene obtained in Examples 1.1-1.3 Properties of polyethylene Viscosity Catalyst Mean average activity particle Standard Bulk molecular Molecular g PP/ size deviation density weight weight Example (g .Math. cat .Math. h) μm μm g/ml ×10.sup.6 g/mol distribution Example 1.1 4000 85 8.21 0.22 1.3 9.2 Example 1.2 3400 76 8.22 0.18 1.7 6.5 Example 1.3 2700 45 8.18 0.16 2.7 3.1 Comparative 4500 110 8.24 0.31 0.5 12.1 Example 1.1

(96) Other properties of the polyethylene obtained in Example 1.3 and Comparative Example 1.1 were further determined in the present invention. It was found that (1) the wear resistance index of the polyethylene in Example 1.3 was several times higher than that of common carbon steel or copper, while the wear resistance index of the polyethylene in Comparative Example 1.1 was slightly lower; (2) the impact strength of the polyethylene in Example 1.3 was higher than 10 KJ/m.sup.2, while the impact strength in Comparative Example 1.1 was around 3 KJ/m.sup.2; (3) chemical corrosion resistance of the polyethylene powder in Example 1.3 was better than that of common polyolefin, while the polyethylene powder in Comparative Example 1.1 was easily degradable under acidic conditions; (4) operating temperature range of the polyethylene powder in Example 1.3 was wider, which can maintain good toughness and high strength at lower (e.g. −30° C.) or higher temperatures (e.g. 110° C.).

Example 2.1 Preparation of Grafted Polyethylene

(97) Preparation of PE-g-MAH: in the reactor completely purged with high purity nitrogen gas, add 40 g of the polyethylene particles prepared in Example 1.1, which has a mean particle size of 85 μm (a standard deviation of 8.21 μm, a viscosity average molecular weight of 1.3×10.sup.6, a molecular weight distribution of 9.2), add 2.0 g of benzoyl peroxide, add 2.8 g of maleic anhydride (MAH), add 4 mL of tetrahydrofuran and 5 mL of xylene; then turn on mechanical agitation and rapidly stir for 3 hours; finally, place the reactor in an oil bath at 100° C. and react for 2 hours to obtain a crude grafted product.

(98) Purification of PE-g-MAH: weigh about 4 g of the crude grafted product, which is added to a 500 mL distillation flask with 200 mL of xylene to be heated and dissolved; reflux the mixture for 4 h; after cooling, add acetone (about 200 mL) to the flaskand and shake well; filter the mixture after standing precipitate and then wash once with acetone; dry the filtrate in an oven at 50° C. for 12 h, and cool down to obtain a purified grafted product.

(99) IR characterization of PE-g-MAH: the infrared spectra of the purified grafted product were determined according to the above-described method, and the results were shown in FIG. 2, wherein the upper spectrum was the polyethylene raw material (i.e., the base polymer) and the lower was the grafted polyethylene. The characteristic peaks of maleic anhydride are at 1862 cm.sup.−1, 1785 cm.sup.−1 and 1717 cm.sup.−1, indicating that maleic anhydride was successfully grafted onto the polyethylene chains.

(100) Water Contact Angle Measurement: water contact angles were determined according to the above-described method. The water contact angle of the polyethylene raw material (i.e., the base polymer) was 95°, while the water contact angle of the grafted polyethylene was 88°.

(101) Determination of the effective grafting rate of PE-g-MAH: the effective grafting rate of the grafted polyethylene was 1.33% according to the above-described method.

Example 2.2 Preparation of Grafted Polyethylene

(102) Preparation of PE-g-MAH: in the reactor completely purged with high purity nitrogen gas, add 40 g of the polyethylene powder prepared in Example 1.1, which has a mean particle size of 76 μm (a standard deviation of 8.22 μm, a viscosity average molecular weight of 1.7×10.sup.6), add 2.0 g of azobisisobutyronitrile, add 2.8 g of maleic anhydride (MAH), add 3 mL of tetrahydrofuran and 6 mL of xylene; then turn on mechanical agitation and rapidly stir for 3 hours; finally, place the reactor in an oil bath at 120° C. and react for 2 hours to obtain a product. The effective grafting rate of the grafted polyethylene with maleic anhydride was determined to be 1.65%, and the water contact angle of the grafted polyethylene was 84°.

Example 2.3 Preparation of Grafted Polyethylene

(103) Preparation of PE-g-AA: in the reactor completely purged with high purity nitrogen gas, add 40 g of the polyethylene powder prepared by the same method as in Example 1.1, which has a mean particle size of 45 μm (a standard deviation of 8.18 μm, a viscosity average molecular weight of 2.7×10.sup.6), add 2.0 g of benzoyl peroxide, add 2.8 g of acrylic acid and 5 mL of xylene; then turn on mechanical agitation and rapidly stir for 3 hours; finally, place the reactor in an oil bath at 100° C. and react for 2 hours to obtain a product. The effective grafting rate of the grafted polyethylene with acrylic acid was determined to be 2.14%, and the water contact angle of the grafted polyethylene was 80°.

Example 2.4 Preparation of Grafted Polyethylene

(104) Preparation of PE-g-MMA: in the reactor completely purged with high purity nitrogen gas, add 40 g of the polyethylene powder prepared by the same method as in Example 1.1, which has a mean particle size of 70 μm (a standard deviation of 8.21 μm, a viscosity average molecular weight of 1.3×10.sup.6), add 2.0 g of benzoyl peroxide, add 2.8 g of methyl methacrylate and 5 mL of xylene; then turn on mechanical agitation and rapidly stir for 4 hours; finally, place the reactor in an oil bath at 100° C. and react for 2 hours to obtain a product. The effective grafting rate of the grafted polyethylene with MMA was determined to be 2.04%, and the water contact angle of the grafted polyethylene was 81°.

Preparation Example 3.1 Glass Fiber

(105) In the mixer, glass fibers and a coupling agent were added and stirred for 30 minutes; a diluent was further added and stirred for 30 minutes; and the treated glass fibers of the present invention were obtained. Wherein, the coupling agent was γ-aminopropyltriethoxysilane KH550; the length of the glass fibers was 3-5 mm; and the diluent was white oil. The weight ratio of the diluent to the coupling agent was 3:1; the coupling agent was used in an amount of 2 parts by weight per 100 parts by weight of the glass fibers.

Preparation Example 3.2 Glass Fiber

(106) In the mixer, glass fibers and a coupling agent were added and stirred for 30 minutes; a diluent was further added and stirred for 30 minutes; and the treated glass fibers of the present invention were obtained. Wherein, the coupling agent was vinyltrimethoxysilane A-171; the length of the glass fibers was 3-5 mm; and the diluent was white oil. The weight ratio of the diluent to the coupling agent was 4:1; the coupling agent was used in an amount of 1 part by weight per 100 parts by weight of the glass fibers.

Preparation Example 3.3 Glass Fiber

(107) In the mixer, glass fibers and a coupling agent were added and stirred for 30 minutes; a diluent was further added and stirred for 30 minutes; and the treated glass fibers of the present invention were obtained. Wherein, the coupling agent was vinyltriethoxysilane A-151; the length of the glass fibers was 3-5 mm; and the diluent was liquid paraffin. The weight ratio of the diluent to the coupling agent was 6:1; the coupling agent was used in an amount of 3 parts by weight per 100 parts by weight of the glass fibers.

Examples 3.1-3.9 Glass Fiber-Reinforced Polyethylene Composition

(108) The composition and content of the compositions of Examples 3.1-3.9 of the present invention are listed in Table 2.

(109) TABLE-US-00002 TABLE 2 Different ratios of glass fiber-reinforced polyethylene compositions Weight Weight Example Polyethylene percent Glass fiber percent 3.1a Ethylene homopolymer of 60 Glass fiber of Preparation 40 Example 1.1 Example 3.1 3.1b Ethylene homopolymer of 50 Glass fiber of Preparation 50 Example 1.1 Example 3.1 3.1c Ethylene homopolymer of 40 Glass fiber of Preparation 60 Example 1.1 Example 3.1 3.2a Ethylene homopolymer of 60 Glass fiber of Preparation 40 Example 1.2 Example 3.1 3.2b Ethylene homopolymer of 50 Glass fiber of Preparation 50 Example 1.2 Example 3.1 3.2c Ethylene homopolymer of 40 Glass fiber of Preparation 60 Example 1.2 Example 3.1 3.3a Ethylene homopolymer of 60 Glass fiber of Preparation 40 Example 1.3 Example 3.1 3.3b Ethylene homopolymer of 50 Glass fiber of Preparation 50 Example 1.3 Example 3.1 3.3c Ethylene homopolymer of 40 Glass fiber of Preparation 60 Example 1.3 Example 3.1 3.4a Ethylene homopolymer of 60 Glass fiber of Preparation 40 Example 1.1 Example 3.2 3.4b Ethylene homopolymer of 50 Glass fiber of Preparation 50 Example 1.1 Example 3.2 3.4c Ethylene homopolymer of 40 Glass fiber of Preparation 60 Example 1.1 Example 3.2 3.5a Ethylene homopolymer of 60 Glass fiber of Preparation 40 Example 1.2 Example 3.2 3.5b Ethylene homopolymer of 50 Glass fiber of Preparation 50 Example 1.2 Example 3.2 3.5c Ethylene homopolymer of 40 Glass fiber of Preparation 60 Example 1.2 Example 3.2 3.6a Ethylene homopolymer of 60 Glass fiber of Preparation 40 Example 1.3 Example 3.2 3.6b Ethylene homopolymer of 50 Glass fiber of Preparation 50 Example 1.3 Example 3.2 3.6c Ethylene homopolymer of 40 Glass fiber of Preparation 60 Example 1.3 Example 3.2 3.7a Ethylene homopolymer of 60 Glass fiber of Preparation 40 Example 1.1 Example 3.3 3.7b Ethylene homopolymer of 50 Glass fiber of Preparation 50 Example 1.1 Example 3.3 3.7c Ethylene homopolymer of 40 Glass fiber of Preparation 60 Example 1.1 Example 3.3 3.8a Ethylene homopolymer of 60 Glass fiber of Preparation 40 Example 1.2 Example 3.3 3.8b Ethylene homopolymer of 50 Glass fiber of Preparation 50 Example 1.2 Example 3.3 3.8c Ethylene homopolymer of 40 Glass fiber of Preparation 60 Example 1.2 Example 3.3 3.9a Ethylene homopolymer of 60 Glass fiber of Preparation 40 Example 1.3 Example 3.3 3.9b Ethylene homopolymer of 50 Glass fiber of Preparation 50 Example 1.3 Example 3.3 3.9c Ethylene homopolymer of 40 Glass fiber of Preparation 60 Example 1.3 Example 3.3

Examples 3.10-3.18

(110) Compositions of Examples 3.1-3.9 were used to prepare sheets, respectively.

(111) The composition of Example 3.1a was used as an example. 6 kg of the ethylene homopolymer of Example 1.1 and 4 kg of the glass fiber of Preparation Example 3.1 were homogenously mixed with a high-speed mixer, added into an extruder, extruded through a slit die, cooled and stretched to produce the sheet of the present invention. Wherein, the processing temperature of the extruder was 180° C. to 240° C.

(112) The performance test results of the sheets prepared in Examples 3.10-3.18 are shown in Table 3.

(113) TABLE-US-00003 TABLE 3 The performance test results of the sheets prepared in Examples 3.10-3.18 Charpy Heat notched Bending Bending Tensile distortion impact strength modulus strength temperature Operating strength (2 (2 (10 (1.8 MPa Creep temperature (7.5 J) mm/min) mm/min) mm/min) 3.2 mm) Example % range ° C. KJ/m.sup.2 MPa MPa MPa ° C. 3.10a 1.6 30 to 12.0 35.7 4753 43.2 117 −135 3.10b 1.5 30 to 11.5 36.4 4668 41.9 113 −135 3.10c 1.8 30 to 13.0 36.1 4702 40.8 110 −135 3.11a 1.5 30 to 13.2 36.3 4683 40.3 118 −135 3.11b 1.6 30 to 14.1 37.4 4653 42.9 117 −135 3.11c 1.7 30 to 13.6 35.9 4689 45.3 115 −135 3.12a 1.9 30 to 11.7 36.1 4721 44.4 116 −135 3.12b 1.6 30 to 12.8 35.9 4693 46.3 118 −135 3.12c 1.7 30 to 11.9 34.6 4706 42.7 113 −135 3.13a 1.8 30 to 14.5 36.2 4696 49.3 113 −135 3.13b 1.9 30 to 15.2 36.3 4683 45.3 114 −135 3.13c 1.6 30 to 13.6 37.4 4753 40.2 113 −135 3.14a 1.7 30 to 13.7 37.6 4781 43.8 116 −135 3.14b 1.9 30 to 14.8 35.6 4612 41.6 113 −135 3.14c 2.0 30 to 13.9 36.9 4599 42.1 114 −135 3.15a 2.0 30 to 15.1 35.8 4601 42.9 111 −135 3.15b 1.8 30 to 14.2 35.6 4713 43.1 117 −135 3.15c 1.9 30 to 14.9 36.2 4702 44.1 114 −135 3.16a 1.8 30 to 12.6 37.6 4681 41.3 111 −135 3.16b 1.6 30 to 13.3 36.8 4836 42.9 115 −135 3.16c 1.5 30 to 13.2 36.3 4706 47.1 117 −135 3.17a 1.6 30 to 13.5 36.8 4638 40.9 113 −135 3.17b 1.7 30 to 12.6 37.4 4723 45.8 116 −135 3.17c 1.8 30 to 12.9 35.9 4603 43.7 117 −135 3.18a 2.0 30 to 14.5 35.6 4821 44.1 115 −135 3.18b 1.8 30 to 15.2 36.1 4773 47.3 118 −135 3.18c 1.9 30 to 14.9 35.9 4693 45.6 112 −135

Examples 3.19-3.27

(114) Compositions of Examples 3.1-3.9 were used to prepare pipes, respectively.

(115) The composition of Example 3.1a was used as an example. 6 kg of the ethylene homopolymer of Example 1.1 and 4 kg of the glass fiber of Preparation Example 3.4 were homogenously mixed with a high-speed mixer, added into an extruder, extruded through a pipe die, cooled and stretched to produce the pipe of the present invention. Wherein, the processing temperature of the extruder was 180° C. to 240° C. The wall thickness of the pipe was in the range of 0.5-5 mm.

(116) The performance test results of the pipes produced in Examples 3.19-3.27 were similar to those of the corresponding sheets.

Example 4.1 Solubilized Ethylene Slurry Polymerization

(117) The slurry polymerization process was used. Firstly, the polymerization reactor was pretreated (under the protection of high purity nitrogen, a 5 L high pressure reactor was dried and deoxidized), 500 g of a dispersing medium of cyclohexane was added. 150 mL of n-Hexane, 20 mg of the catalyst prepared as described in the above Preparation Example 1 and 12 ml of triethyl aluminum were sequentially added, and then ethylene gas was fed into the reactor to keep the reactor pressure at 0.7 MPa; wherein, in ethylene, the content of carbon monoxide was less than 5 ppm, the content of carbon dioxide was less than 15 ppm, and the content of conjugated diene was less than 10 ppm; the polymerization reaction started, the system temperature was maintained at 80° C., and the reaction time was 30 minutes. After the polymerization, it was cooled down. The slurry material was directly discharged from the bottom valve, the required amount of white oil was added, and the dispersion medium was removed by distillation to obtain the solubilized ultra-high molecular weight, ultra-fine particle size ethylene homopolymer of the present invention, wherein the weight percent of white oil was 30 wt %. The properties of the obtained polyethylene are shown in Table 4.

(118) Comparative dissolution experiment: 10 g of the ultra-high molecular weight, ultra-fine particle size ethylene homopolymer containing white oil prepared in Example 4.1 was added into 60 g of white oil, and dissolved at 140° C. for 20 minutes.

(119) 7 g of the ultra-high molecular weight, ultra-fine particle size ethylene homopolymer prepared in Comparative Example 4.1 was added into 63 g of white oil, and dissolved at 140° C. for 90 minutes.

Example 4.2 Solubilized Ethylene Slurry Polymerization

(120) The slurry polymerization process was used. Firstly, the polymerization reactor was pretreated (under the protection of high purity nitrogen, a 5 L high pressure reactor was dried and deoxidized), and 500 g of a dispersing medium of n-pentane was added. 150 mL of n-Hexane, 20 mg of the catalyst prepared as described in the above Preparation Example 1 and 12 ml of triethyl aluminum were sequentially added, and then ethylene gas was fed into the reactor to keep the reactor pressure at 0.7 MPa; wherein, in ethylene, the content of carbon monoxide was less than 5 ppm, the content of carbon dioxide was less than 15 ppm, and the content of conjugated diene was less than 10 ppm; the polymerization reaction started, the system temperature was maintained at 70° C., and the reaction time was 30 minutes. After the polymerization, it was cooled down. The slurry material was directly discharged from the bottom valve, the required amount of white oil was added, and the dispersion medium was removed by distillation to obtain a solubilized ultra-high molecular weight, ultra-fine particle size ethylene homopolymer, wherein the weight percent of white oil was 40 wt %. The properties of the obtained polyethylene are shown in Table 4.

(121) Solubility was determined by a method similar to that of Example 4.1. The dissolution time was shortened by nearly 80% compared to the polymer with zero solvent content.

Example 4.3 Solubilized Ethylene Slurry Polymerization

(122) The slurry polymerization process was used. Firstly, the polymerization reactor was pretreated (under the protection of high purity nitrogen, a 5 L high pressure reactor was dried and deoxidized), and 500 g of a dispersing medium of cyclohexane and the required amount of white oil were added. 20 mg of the catalyst prepared as described in the above Preparation Example 1 and 12 ml of triethyl aluminum were sequentially added, and then ethylene gas was fed into the reactor to keep the reactor pressure at 0.7 MPa; wherein, in ethylene, the content of carbon monoxide was less than 5 ppm, the content of carbon dioxide was less than 15 ppm, and the content of conjugated diene was less than 10 ppm; the polymerization reaction started, the system temperature was maintained at 50° C., and the reaction time was 30 minutes. After the polymerization, it was cooled down. The slurry material was directly discharged from the bottom valve, and the dispersion medium was removed by distillation to obtain the solubilized ultra-high molecular weight, ultra-fine particle size ethylene homopolymer of the present invention, wherein the weight percent of white oil was 30 wt %. The properties of the obtained polyethylene are shown in Table 4.

(123) Solubility was determined by a method similar to that of Example 4.1. The dissolution time was shortened by nearly 80% compared to the polymer with zero solvent content.

(124) Scanning electron microscopy analysis showed that the polyethylene particles prepared in Examples 4.1-4.3 exhibited good sphericity, spherical or spheroidal, and had a relatively uniform particle size distribution and smaller average particle diameter.

Comparative Example 4.1 Ethylene Homopolymer and Preparation Thereof

(125) Under the protection of high purity nitrogen, a 1 L high pressure reactor was dried and deoxidized. 150 mL of n-Hexane, 20 mg of the catalyst prepared as described in the above Preparation Example 1 and 12 ml of triethyl aluminum were sequentially added, and then ethylene gas was fed into the reactor to keep the reactor pressure at 0.7 MPa; wherein, in ethylene, the content of carbon monoxide was less than 5 ppm, the content of carbon dioxide was less than 15 ppm, and the content of conjugated diene was less than 10 ppm; the polymerization reaction started, the system temperature was maintained at 80° C., and the reaction time was 30 minutes to obtain the ethylene homopolymer.

Comparative Example 4.2 Ethylene Bulk Polymerization

(126) Using a method similar to that of Example 4.1, except for the polymerization temperature and the purity of the monomer, wherein, the purity of ethylene is that the content of carbon monoxide was more than 10 ppm, the content of carbon dioxide was more than 20 ppm, and the content of conjugated diene was more than 20 ppm; the system temperature was maintained at 110° C. The catalyst activity and the properties of the polyethylene are shown in Table 4.

(127) TABLE-US-00004 TABLE 4 The catalyst activity of the Ziegler-Natta catalyst prepared in Preparation Example 1 and the properties of the polyethylene obtained in Examples 4.1-4.3 Properties of polyethylene Viscosity Mean average Catalyst particle Standard Bulk molecular Molecular activity size deviation density weight weight Example g PP/(g cat h) μm μm g/ml ×10.sup.6 g/mol distribution Example 4.1 4000 85 8.21 0.22 1.3 9.2 Example 4.2 3400 76 8.22 0.18 1.7 6.5 Example 4.3 2700 45 8.18 0.16 2.7 3.1 Comparative 4500 110 8.24 0.31 0.5 12.1 Example 4.2

(128) Other properties of the polyethylene obtained in Examples 4.1-4.3 were further determined in the present invention. It was found that (1) the wear resistance indexs of the polyethylene in Examples 4.1-4.3 were several times higher than that of common carbon steel or copper, while the wear resistance index of the polyethylene in Comparative Example 4.1 was slightly lower; (2) the impact strengths of the polyethylene in Examples 4.1-4.3 were higher than 10 KJ/m.sup.2, while the impact strength in Comparative Example 4.1 was around 3 KJ/m.sup.2; (3) chemical corrosion resistances of the polyethylene powder in Examples 4.1-4.3 were better than that of common polyolefin, while the polyethylene powder in Comparative Example 4.1 was easily degradable under acidic conditions; (4) operating temperature range of the polyethylene powder in Examples 4.1-4.3 was wider, which can maintain good toughness and high strength at lower (e.g. −30° C.) or higher temperatures (e.g. 110° C.).

Example 5.1 Preparation of Fiber

(129) The solubilized ultra-high molecular weight, ultra-fine particle size polyethylene of Example 4.1 was mixed with while oil to obtain a mixture, wherein the content of the polymer was 10 wt %; the mixture was dissolved and extruded through a twin-screw extruder, and the temperature of the dissolution extrusion was 200° C. to obtain a spinning solution; the spinning solution was directly extruded with a twin-screw extruder through a spinning assembly and a spinneret, and passed through a cooling water bath (the water bath temperature was 5° C.) to obtain a gel fiber; the gel fiber was via the processes of gel wire drawing, solvent extraction, drying, first hot-box dry-hot drawing, second hot-box dry-hot drawing, heat setting and winding, to obtain the fiber of the present invention.

(130) In the process step of processing the above-described gel fiber into a fiber, the drawing temperature during the gel wire drawing process was 40° C., the draw multiple was 10 times; the extractant during the process of extracting the solvent was selected from cyclohexane; the drying during the drying process was dried by hot air, the hot air temperature was 60° C.; the temperature during the first hot-box dry-hot drawing process was 130° C., the draw multiple was 10 times; the temperature during the second hot-box dry-hot drawing process was 135° C., the draw multiple was 2 times; the temperature during the heat-setting process was 120° C.

Example 5.2 Preparation of Fiber

(131) Other steps were the same as in Example 5.1, except that an antioxidant was further added in the process of mixing with the solvent in step (1), and the added amount of the antioxidant was 0.05 part by weight, per 100 parts by weight of the polyethylene. The antioxidant was composed of a primary antioxidant and a secondary antioxidant, wherein the primary antioxidant was selected from 2,6-di-tert-butyl-4-methylphenol, and the secondary antioxidant was selected from didodecyl thiodipropionate.

(132) The properties of the fibers prepared in Examples 5.1 and 5.2 are listed in Table 5.

(133) TABLE-US-00005 TABLE 5 Performance test results of the fibers prepared in Examples 5.1 and 5.2 Operating Breaking Elongation Melting temperature Fineness strength Modulus at break Creep Crystallinity point range Number dtex GPa GPa % % % ° C. ° C. Example 5.1 2.5 2.5 120 3.0 2.0 95 134 −30 to 130 Example 5.2 2.5 3.0 220 3.5 1.5 95 140 −30 to 135

(134) The data shown in Table 5 indicate that the fiber of the present invention has excellent creep resistance, a wider operating temperature range, and great application prospects.

Example 6.1 Preparation of Film

(135) 1) The raw material containing the solubilized ultra-high molecular weight, ultra-fine particle size polyethylene and a solvent for film formation were melt mixed to obtain a solution;

(136) the polymer was the solubilized ultra-high molecular weight, ultra-fine particle size polyethylene prepared in Example 4.1. Meanwhile, an antioxidant was added, and the added amount of the antioxidant was 0.1 part by weight, per 100 parts by weight of the polymer. The antioxidant was composed of a primary antioxidant and a secondary antioxidant, wherein the primary antioxidant was selected from 2,6-di-tert-butyl-4-methylphenol, and the secondary antioxidant was selected from didodecyl thiodipropionate. The solvent for film formation was liquid paraffin. In the solution, the weight percent of the polymer was 30 wt %;

(137) the melt mixing was carried out by a known twin-screw extruder, wherein the temperature of the melt mixing was 180-250° C.

(138) 2) The solution was extruded, and a molded body was formed and cooled to produce a polymer sheet. Specifically, the solution of step (1) was extruded from a mold to form a molded body (such as a sheet) during supplying the solution to a mold through an extruder, and a polymer sheet was obtained after cooling by a cooling drum. The surface temperature of the cooling drum was set to 20-40° C., and the cooling rate of the molded body through the cooling drum was more than 20° C./s;

(139) 3) The biaxial stretching was used to produce a thin film; the stretching was carried out by a drum method, wherein, the longitudinal stretching multiple was 5 times and the transverse stretching multiple was 5 times.

Examples 6.2-6.6 Preparation of Film

(140) Other steps were the same as in Example 6.1, and the differences were listed in Table 6.

(141) TABLE-US-00006 TABLE 6 Specific conditions or parameters of Examples 6.2-6.6 Transverse Longitudinal Stretching stretching stretching Polymer mode multiple multiple Example 6.2 Example 4.1 Biaxial 4 4 stretching Example 6.3 Preparation Biaxial 4 5 Example 4.1 stretching Example 6.4 Preparation Biaxial 4 5 Example 4.1 stretching Example 6.5 Preparation Uniaxial 5 4 Example 4.1 stretching Example 6.6 Preparation Uniaxial 5 4 Example 4.1 stretching

(142) The properties of the films prepared in Examples 6.1-6.6 are listed in Table 7.

(143) TABLE-US-00007 TABLE 7 Performance test results of the films prepared in Examples 6.1-6.6 Reference Example Example Example Example Example Example value 6.1 6.2 6.3 6.4 6.5 6.6 Film thickness 15-60 25 25 25 25 25 25 (μm) Tensile strength >90 150 120 150 150 120 120 (Longitudinal) (MPa) Tensile strength >35 150 120 120 120 150 150 (Transverse) (MPa) Elongation at break >40 61 60 63 62 61 62 (%) Puncture strength >3 5.5 6.5 6.8 5.9 5.9 5.9 (N) Melting >160 170 172 168 165 171 165 temperature (° C. ) Porosity (%) 30-60 33 36 39 37 39 43 Pore size distribution  40-100 54 51 53 49 52 49 (nm) Permeability (25 μm), <30 19 18 17 19 18 17 s/40 ml. 1in2. 31 mm H.sub.2O Heat shrinkage ratio <2 1.0 1.2 1.3 1.2 1.1 1.0 (120° C. , 1 h) (%)

(144) The embodiments of the present invention are described above. However, the present invention is not limited to the above embodiments. Any modification, equivalent alternative, improvement, etc., falling within the spirit and scope of the present invention, are intended to be included within the scope of the present invention.