AU2011265575A1

AU2011265575A1 - A method for preparing a high-strength polyethylene continuous fiber and the resulting product

Info

Publication number: AU2011265575A1
Application number: AU2011265575A
Authority: AU
Inventors: Huanmin Zhou
Original assignee: JIANGSU ZJA NEW MATERIAL CO Ltd
Current assignee: JIANGSU ZJA NEW MATERIAL CO Ltd
Priority date: 2011-09-23
Filing date: 2011-12-23
Publication date: 2013-04-11
Anticipated expiration: 2031-12-23
Also published as: CN102418157B; CN102418157A; AU2011265575B2

Abstract

Abstract The invention discloses a method for preparing a high-strength polyethylene continuous fiber, comprising the steps of: (a) placing a linear polyethylene powder into a solvent of paraffin, and extruding the dissolved solution through a spinneret after deaeration at high temperature, and then cooling the extruded solution to further form an as-spun gel filament; (b) placing the as-spun gel filament into a vacuum environment with the temperature of 40*C-120'C and keeping it on standing, wherein the standing time is 3-84 hours; (c) extracting the gel filament by a multi-stage process; (d) drying the fiber after extraction; (e) taking the dried fiber into a multi-drawing process. The invention also discloses a product made according to the above method for preparing a high-strength polyethylene continuous fiber. In the method for preparing a high-strength polyethylene continuous fiber according to the invention, the standing time is shortened by employing the above technical solution, and the as-spun gel filament is placed on standing in a vacuum environment with a temperature over room temperature, in order to facilitate the phase separation of the gel filament, as well as a large amount of solvent is separated out, thereby decreasing the amount of extractant used.

Description

- 1 AUSTRALIA PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT ORIGINAL Name of Applicant: Jiangsu ZJA New Material Co., Ltd Actual Inventor: Huanmin Zhou Address for Service is: SHELSTON IP 60 Margaret Street Telephone No: (02) 9777 1111 SYDNEY NSW 2000 Facsimile No. (02) 9241 4666 CCN: 3710000352 Attorney Code: SW Invention Title: A method for preparing a high-strength polyethylene continuous fiber and the resulting product The following statement is a full description of this invention, including the best method of performing it known to me/us: File: 73165AUP00 2 A method for preparing a high-strength polyethylene continuous fiber and the resulting product Field of the invention The present invention relates to a method for preparing a high-strength polyethylene continuous fiber and the resulting product. Background of the invention The high-strength polyethylene fiber prepared by the ultra-drawing technology of gel spinning has the greatest tensile strength and tensile modulus among the flexible chain polymer materials, and is the optimum material for making high-strength ropes, high-strength textile products, bulletproof clothes and bulletproof armor. All the existing methods for preparing a high-strength polyethylene fiber employ high-drawing process of solvent spinning, and these can be divided into two types in terms of different solvents used: (1) Using decahydronaphthalene with good volatility as a solvent for polyethylene, an ultra high molecular weight polyethylene is dissolved in decahydronaphthalene, and the mixed solution forms a gel as-spun fiber after extruding through a spinneret orifice, while the decahydronaphthalene is taken out from the fiber by hot air flow and volatilized by utilizing the advantageous volatility of decahydronaphthalene, and then the as-spun fiber is ultra-stretched by over 20 times, which makes the large molecules in the fiber arrange with full extension, and a fiber having a strength of over 2.0 GPa is achieved (for example, see Chinese patent, 01123737.6). The features of the aforementioned method consist in a simple process and only one solvent being required during the production, but there are some obvious disadvantages in the method: on the one hand, the concentration of the spinning solution made by the method is limited, due to the great volatility of decahydronaphthalene, thus, usually higher temperature is 3 needed to achieve the dissolution when the concentration is very high, however this enhanced temperature will intensify the volatilization, and hence the concentration of the solution is limited to less than 8% generally in the practical use; on the other hand, it is difficult to recycle the vaporized decahydronaphthalene due to the great volatility thereof, so that high environmental pressure is required during the production, and also the cost is high. (2) Using the paraffin with low volatility as a solvent, an ultra high molecular weight polyethylene is dissolved into the paraffin, the mixed solution forms a gel as-spun fiber after extruding through a spinneret orifice, subsequently the solvent is displaced from the nascent filament with an easily volatilized extractant, and then the extractant is volatilized with a hot air flow, and a ultra-drawing of over 20 times is carried out, which makes the large molecules in the fiber arrange with full extension, and a fiber having a strength of over 2.0 GPa is achieved (for example, see Chinese patent 02160744.3). The method avoids the disadvantages of decahydronaphthalene, and the concentration of the spinning solution can be up to 10%, but it is necessary to perform the extraction process because two solvents are used in the method, moreover, in order to make the structure of the as-spun fiber more stable, a balance in normal temperature for a long time is generally employed, this stabilizes the structure of the nascent filament, also, some of the spinning solvent is separated out by means of phase separation, thereby decreasing the amount of extractant used, so that the overstocking of the nascent filament is severe, and which is adverse to the enhancement of the productivity. For example, 100g of straight-chain ultra high molecular weight polyethylene powder having a relative molecular mass of 4,000,000 and 10OOg of industrial white oil are placed into a mixing tank, the mixed solution is stirred at high speed in normal temperature for 25 minutes, with a stirring rate of 2000 r/min, subsequently the stirred solution is introduced 4 into a co-rotating twin screw with 35 mm of diameter and an aspect ratio of 64 to dissolve and deaerate, and then the obtained solution is extruded through a spinneret under the pressure of 1OMPa, and into a coagulating bath of 20 0 C to cool and further form an as-spun gel fiber, next, the fiber was balanced on standing for 92 hours in normal pressure and a temperature of 20 0 C, accordingly, the solid content of the gel filament after standing is 18%, the fiber after standing is extracted with 15OOg of toluene and dried, and the fiber is stretched up to 38 times by four step-wise drawings, the strength of the obtained final product of fiber is 2.21 MPa. Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of common general knowledge in the field. Summary of the invention In order to overcome the aforementioned disadvantages, the object of the invention is to provide a method for preparing a high-strength polyethylene continuous fiber and the resulting product. It is an object of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative. In order to achieve the above purpose, the technical solution employed in the invention is a method for preparing a high-strength polyethylene continuous fiber, which comprises the following steps: (a) placing a linear polyethylene powder into a solvent of paraffin, and heating the mixed uniform suspension until dissolved, subsequently extruding the obtained solution through a spinneret after deaeration at high temperature, and then cooling the extruded solution to further form an as-spun gel filament; (b) placing the as-spun gel filament into a vacuum environment with the temperature of 40'C-120*C and keeping it on standing, the standing time is 5 from 3 to 84 hours, preferably 12 to 72 hours; (c) dipping the gel filament after standing into a extractant to extract the gel filament by a multi-stage process, in order to displace the paraffin solvent from the gel filament; (d) drying the fiber after extraction; (e) taking the dried fiber into a multi-drawing process. Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise", "comprising", and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of "including, but not limited to". Preferably, in the step (a), the relative molecular mass of the linear polyethylene is 1,000,000 to 8,000,000. In an embodiment, in the step (a), the content of the polyethylene in the suspension is from 2% by weight to 20% by weight. In an another embodiment, in the step(a), the paraffin solvent is selected from the group of straight-chain alkanes having a carbon number of 8 to 100, branched alkanes, cycloalkanes or the derivatives thereof. Preferably, in the step (a), the content of the polyethylene in the as-spun gel filament is from 1.5% by weight to 18% by weight. More preferably, in the step (b), the residual pressure of the vacuum environment is 0-9000Pa, preferably 50-8500Pa. More preferably, in the step (b), the environment temperature is 45-80 0 C preferably. In a further embodiment, in the step (c), the extractant is selected from one of benzene, toluene, xylene, gasoline, haloalkanes, straight-chain alkanes of C 4

-C

8 , branched alkanes, cycloalkanes, or any combination thereof. In a still further embodiment, in the step(c), the ratio between the gel filament and the extractant is between 1:5 and 1:10 during the extraction.

6 The other technical solution provided by the present invention is a product made according to the method for preparing a high-strength polyethylene continuous fiber. By utilizing the above technical solutions, the invention discloses a novel method for preparing a high strength polyethylene continuous fiber and the resulting product. In the method, some variations are made to the standing in normal temperature in the prior art, i.e. , the standing time is shorten to 3-84 hours, while the as-spun gel filament is placed on standing in the vacuum environment at a temperature over room temperature, in order to promote the phase separation of the gel filament and make a lot of solvent separate out, thereby the solid content of the gel filament entering into the subsequent drawing process is enhanced up to above 20%, and the amount of the extractant used is decreased, then the subsequent extraction and hot drawing are performed, finally the direct consumption amount of the extractant is decreased to 2-10 kg during the production of one kilogram high-strength polyethylene fiber. Detailed description of the invention The preferred embodiments of the invention are described in further detail in the following, so that the advantages and features can be appreciated by those skilled in the art easily, thereby the protection scope of the invention can be defined more clearly and definitely. Embodiment I A method for preparing a high-strength polyethylene continuous fiber, which comprises the following steps: (a) 100g of straight-chain ultra high molecular weight polyethylene powder having a relative molecular mass of 4,500,000 and 10OOg of industrial white oil are placed into a mixing tank, the mixed solution is stirred at high speed in normal temperature for 25 minutes, with a stirring rate of 2000 r/min, subsequently the stirred solution is introduced into a 7 co-rotating twin screw with 35 mm of diameter and a aspect ratio of 64 to dissolve and deaerate, and then the obtained solution is extruded through a spinneret under a pressure of 1OMPa, next, the extruded solution is taken into a coagulating bath of 0-35*C to cool after through a air gap of 1-30mm. In the coagulating bath of this embodiment, the water of 20*C is applied to cool the solution flow of polyethylene at high temperature, and the solution flow of polyethylene cools to further form an as-spun gel fiber; (b) The as-spun gel filament is balanced on standing for 28 hours in a vacuum environment with a residual pressure of 8000Pa and a temperature of 70*C; (c) The solid content of the gel filament after standing is 25%, the fiber after standing is extracted for many times with 700g of xylene, so that all the industrial wine can be displaced completely; (d) The fiber after extraction is dried; (e) The dried fiber is taken into a multi-drawing process, and the fiber is stretched up to 38 times by four step-wise drawing, the strength of the obtained fiber product is 2.73 Mpa. A product made according to the above method for preparing a high-strength polyethylene continuous fiber. Embodiment 2 A method for preparing a high-strength polyethylene continuous fiber, which comprises the following steps: (a) 100g of straight-chain ultra high molecular weight polyethylene powder having a relative molecular mass of 1,500,000 and 5OOg of industrial white oil are placed into a mixing tank, the mixed solution is stirred at high speed in normal temperature for 22 minutes, with a stirring rate of 25OOr/min, subsequently the stirred solution is introduced into a co-rotating twin screw with 35 mm of diameter and a aspect ratio of 64 to dissolve and deaerate, and then the obtained solution is extruded through a spinneret under a pressure of 13MPa, next, the extruded solution is taken 8 into a coagulating bath of 0-35*C to cool after through a air gap of 1-30mm. In the coagulating bath of this embodiment, the water of 20*C is applied to cool the solution flow of polyethylene at high temperature, and the solution flow of polyethylene cools to further form an as-spun gel fiber; (b) The as-spun gel filament is balanced on standing for 58 hours in a vacuum environment with a residual pressure of 7000Pa and a temperature of 90*C; (c) The solid content of the gel filament after standing is 50%, the fiber after standing is extracted for many times with 300g of xylene, so that all the industrial wine can be displaced completely; (d) The fiber after extraction is dried; (e) The dried fiber is taken into a multi-drawing process, and the fiber is stretched up to 42 times by four step-wise drawing, the strength of the obtained fiber product is 2.65 Mpa. A product made according to the above method for preparing a high-strength polyethylene continuous fiber. Embodiment 3 A method for preparing a high-strength polyethylene continuous fiber, which comprises the following steps: (a) 100g of straight-chain ultra high molecular weight polyethylene powder having a relative molecular mass of 6,500,000 and 3000g of industrial wine are placed into a mixing tank, the mixed solution is stirred at high speed in normal temperature for 20 minutes, with a stirring rate of 1900 r/min, subsequently the stirred solution is introduced into a co-rotating twin screw with 35 mm of diameter and a aspect ratio of 64 to dissolve and deaerate, and then the obtained solution is extruded through a spinneret under a pressure of 5MPa, next, the extruded solution is taken into a coagulating bath of 0-35 0 C to cool after through a air gap of 1-30mm. In the coagulating bath of this embodiment, the water of 200C is applied to cool the solution flow of polyethylene at high temperature, and the solution flow 9 of polyethylene cools to further form an as-spun gel fiber; (b) The as-spun gel filament is balanced on standing for 66 hours in a vacuum environment with a residual pressure of 10OPa and a temperature of 40*C; (c) The solid content of the gel filament after standing is 30%, the fiber after standing is extracted for many times with 900g of xylene, so that all the industrial wine can be displaced completely; (d) The fiber after extraction is dried; (e) The dried fiber is taken into a multi-drawing process, and the fiber is stretched up to 48 times by four step-wise drawing, the strength of the obtained fiber product is 3.15 Mpa. A product made according to the above method for preparing a high-strength polyethylene continuous fiber. The above embodiments are only intended to illustrate the technical concept and features of the invention, which aim at the content of the invention can be appreciated and embodied by those skilled in the art, and the protection scope of the invention can not be limited therefrom, any equivalent variations or modifications according to the spirit of the invention should be covered within the protection scope of the invention.

Claims

1. A method for preparing a high-strength polyethylene continuous fiber, comprising the steps of: (a) placing a linear polyethylene powder into a solvent of paraffin, and heating the mixed uniform suspension until dissolved, subsequently extruding the obtained solution through a spinneret after deaeration at high temperature, and then cooling the extruded solution to further form an as-spun gel filament; (b) placing the as-spun gel filament into a vacuum environment with the temperature of 40'C-120'C and keeping it on standing, wherein the standing time is from 3 to 84 hours; (c) dipping the gel filament after standing into a extractant to extract the gel filament by a multi-stage process, in order to displace the paraffin solvent from the gel filament; (d) drying the fiber after extraction; (e) taking the dried fiber into a multi-drawing process.

2. The method for preparing a high-strength polyethylene continuous fiber according to claim 1, wherein in step (a), the relative molecular mass of the said linear polyethylene is from 1,000,000 to 8,000,000.

3. The method for preparing a high-strength polyethylene continuous fiber according to claim 1 or claim 1, wherein in step (a), the content of the polyethylene in the said suspension is from 2% by weight to 20% by weight.

4. The method for preparing a high-strength polyethylene continuous fiber according to any one of the preceding claims, wherein in step (a), the said paraffin solvent is selected from the group of straight-chain alkanes having a carbon number of 8 to 100, branched alkanes, cycloalkanes, or the derivatives thereof. 11

5. The method for preparing a high-strength polyethylene continuous fiber according to any one of the preceding claims, wherein in step (a), the content of the polyethylene in the said as-spun gel filament is from 1.5% by weight to18% by weight.

6. The method for preparing a high-strength polyethylene continuous fiber according to any one of the preceding claims, wherein in step (b), the residual pressure of the said vacuum environment is OPa-9000Pa.

7. The method for preparing a high-strength polyethylene continuous fiber according to any one of the preceding claims, wherein in step (b), the environment temperature is 45*-80*.

8. The method for preparing a high-strength polyethylene continuous fiber according to any one of the preceding claims, wherein in step (c), the extractant is selected from one of benzene, toluene, xylene, gasoline, haloalkanes, straight-chain alkanes of C 4 -C 8 , branched alkanes, cycloalkanes or any combination thereof.

9. The method for preparing a high-strength polyethylene continuous fiber according to any one of the preceding claims, wherein in step (c), the ratio between the gel filament and the extractant is between 1:5 and 1:10 during the extraction.

10. A product made by the method according to any one of the preceding claims.

11. A method for preparing a high-strength polyethylene continuous fiber substantially as herein described with reference to any one of the embodiments of the invention illustrated in the accompanying examples.