CA2342151A1 - Production of continuous fibre from nanofibres - Google Patents
Production of continuous fibre from nanofibres Download PDFInfo
- Publication number
- CA2342151A1 CA2342151A1 CA 2342151 CA2342151A CA2342151A1 CA 2342151 A1 CA2342151 A1 CA 2342151A1 CA 2342151 CA2342151 CA 2342151 CA 2342151 A CA2342151 A CA 2342151A CA 2342151 A1 CA2342151 A1 CA 2342151A1
- Authority
- CA
- Canada
- Prior art keywords
- fibre
- nanofibres
- polyethylene
- solvent
- solution
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
-
- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
- D01F1/00—General methods for the manufacture of artificial filaments or the like
- D01F1/02—Addition of substances to the spinning solution or to the melt
- D01F1/10—Other agents for modifying properties
-
- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
- D01F6/00—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof
- D01F6/02—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds
- D01F6/04—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds from polyolefins
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Textile Engineering (AREA)
- Nanotechnology (AREA)
- Physics & Mathematics (AREA)
- Composite Materials (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Materials Engineering (AREA)
- Crystallography & Structural Chemistry (AREA)
- Manufacturing & Machinery (AREA)
- Artificial Filaments (AREA)
Abstract
A process for converting nanofibres to a continuous fibre or yarn is disclosed. The nanofibres such as carbon nanotubes are dispersed in a solution of high molecular weight polyethylene. This solution is spun to a fibre which is subsequently cooled so that the solution gels. This fibre is then stretched to many times its original length and the solvent is removed by extraction or evaporation. The drawing and solvent removal may be carried out in more steps and the order of the treatment may vary. Relatively dilute solution of the polyethylene can be spun a fact which allows high loading of the nanofibres. In the product the nanofibres are essentially aligned along the fibre length due to the very high draw ratios possible in this process. The fibre can be further treated to remove the polyethylene matrix by heating it in an inert atmosphere to about 500 C or the polyethylene can be carbonized thus yielding a fibre of nanofibres in carbon matrix.
Description
PRODUCTION OF CONTINUOUS FIBRE FROM NANOFIBRES.
FIELD OF THE INVENTION.
The invention relates to a process for producing fibres or yarns from nanofibres. More particularly in the process of this invention the nanofibres are dispersed in a solution of high molecular weight polyethylene which is converted to a fibre in a gel spinning process. The fibres are stretched to align the nanofibres along the fibre. The draw ratio is 15 or more. Subsequently, if desired. the polyethylene matrix can be cracked and evaporated by heating the fibre to about 500 C in an inert atmosphere or the polyethylene can be converted to carbon by heating the fibre in an atmosphere with a controlled oxygen content. Commercial gel spinning processes can be used with little or no modifications. The high molecular weight polyethylene solution with the nanofibres dispersed in it can be prepared as presently practiced or the high molecular weight polyethylene can be produced as a slurry in the spinning solvent using polymerization catalyst supported on the nanofibres, the spinning solution then can be prepared by heating this slurry.
BACKGROUND OF THE INVENTION.
Gel spinning processes are known and commercially practiced, for example those described in US 4 137 394, US 4 344 908 and US 5 342 567. In these processes a solution of high molecular weight of polyethylene ( a dope) in a suitable solvent is prepared. The molecular weight of the polyethylene is in the order of a million and more. The higher is the molecular weight of the polyethylene the stronger is the resultant fibre, however the higher is the molecular weight of the polyethylene the more difficult is to prepare the solution.
Polyethylene is soluble only at temperatures above some 120 C, thus the boiling point of the solvent must be higher than this temperature, otherwise it would flash during spinning, which is undesirable. Suitable solvents are pure or mixed hydrocarbons boiling in the range of 150-200 C or hydrocarbons having high boiling point such as mineral oils. Also fluorinated or chlorinated hydrocarbons may be used although this is not practiced in producing gel spun fibres. The polyethylene solution is spun and cooled so that the polyethylene gels, thus yielding a gel fibre of polyethylene containing solvent. To obtain the final product the fibre must be stretched to many times its original length and the solvent removed. The stretching is done at an appropriate temperature in one or multiple steps. The solvent is removed by extraction with a light solvent or it is evaporated or stripped by steam in the case that a volatile solvent is used. The sequence of stretching and solvent removal may follow each other by say solvent removal - stretching -stretching or stretching - solvent removal - stretching or by using a different sequence.
None of the prior art teaches the option of adding an insoluble fibres such as carbon nanotubes to the dope.
High molecular weight polyethylene is known and is commercially available under the name Hostalen GUR, for example.
Nanofibres are known. For example carbon nanotubes are available in research quantities and may soon be available in commercial quantities. Presently only one method for organizing these nanofibres into an oriented fibre is described in Science, 290, 1331 (2000). A dispersion of carbon nanotubes is spun into a stream of poly (vinyl alcohol) solution in water. The process is slow and it is not commercial.
DETAILED DESCRIPTION OF THE INVENTION.
I have now found a process for producing a continuous fibre from nanofilaments using a gel spinning process.
In the process of the invention the nanofibres are added to the solution of the high molecular weight polyethylene in a suitable spinning solvent.
The polyethylene is a linear "high density" polyethylene prepared by any known process.
Its molecular weight may be 100 000 to 10 000 000, preferably 500 000 to 4 000 000. A
polar monomer such as malefic anhydride may be grafted to the polyethylene backbone to provide enhanced bonding between the POLYETHYLENE and the nanofibres in the final product.
The nanofibres may be any fibres of a diameter in the order of 10 nm and of the length to diameter ration greater than 50, preferably greater than 100. Preferably single wall carbon nanotubes can be used.
The solvent may be a hydrocarbon or a similar solvent in which polyethylene is soluble, such as fluorinated or chlorinated hydrocarbon. A mixture of said solvents may be used.
The normal boiling point of the solvent is above the temperature at which polyethylene is soluble in the solvent which is about 120 C. The solvent selection depends on the particular gel spinning process. Lower boiling solvent are advantageously used when the solvent is evaporated from the gel after spinning while high boiling solvents such as mineral oil have to be extracted from the gel. Either process has its advantages and draw-backs, as those skilled in the art would appreciate.
In preparing the solution the nanofibres and the high molecular weight polyethylene can be added to the solvent and in a stirred tank and while stirring the temperature is increased to the desired level. Care must be taken to exclude oxygen. The vessel design and the dissolution procedures are described in the prior art and are well known to those skilled in the art. The molecular weight and concentration of the polyethylene and the concentration of nanofibres in the spinning solution are adjusted so that desired processability and content of the nanofibres in the final product are obtained.
Alternately, the fibre can be dispersed in a purified spinning solvent, and an ethylene polymerization catalyst is then deposited onto the nanofibres, the vessel is pressurized with ethylene which polymerizes and coats the nanofibres. The polymerization catalyst and the temperature are selected so that the resultant polyethylene is of the desired molecular weight. Upon heating to at least the solubilization temperature the polyethylene dissolves and the solution can be used as the spinning solution in the subsequent gel spinning process. This method may provide a more uniform dispersion of the nanofibres.
The temperature of spinning solution must be above the minimum temperature at which the polyethylene is soluble in the solvent used, which is usually 120- 130 C.
However the temperature should not be much higher than the normal boiling temperature of the solvent else it would flash at the spinneret exit which is undesirable.
The orientation of the nanofibres is the result of the shear gradient in the spinneret followed by the considerable reduction in the transverse dimension of the gel fibre caused by the solvent removal and drawing of the fibre. Thus for example a gel fibre spun from a dope which after cooling contains 5 volume % of the nanofibres and 5 volume %
of the polyethylene and drawn 20 times receives orientation similar to a melt spun fibre drawn 200 times.
Nanofibres may be added to the dope and converted to fibre using other solution spinning processes such as those used in the production of poly acrylo nitrile or celulose acetate fibres for example. Although the final orientation would be lower than that achieved in gel spun polyethylene fibres, the product may be quite suitable for some end uses.
There are potentially many uses for such fibres utilizing their strength or electrical properties. However the technology is too new to anticipate all the uses.
FIELD OF THE INVENTION.
The invention relates to a process for producing fibres or yarns from nanofibres. More particularly in the process of this invention the nanofibres are dispersed in a solution of high molecular weight polyethylene which is converted to a fibre in a gel spinning process. The fibres are stretched to align the nanofibres along the fibre. The draw ratio is 15 or more. Subsequently, if desired. the polyethylene matrix can be cracked and evaporated by heating the fibre to about 500 C in an inert atmosphere or the polyethylene can be converted to carbon by heating the fibre in an atmosphere with a controlled oxygen content. Commercial gel spinning processes can be used with little or no modifications. The high molecular weight polyethylene solution with the nanofibres dispersed in it can be prepared as presently practiced or the high molecular weight polyethylene can be produced as a slurry in the spinning solvent using polymerization catalyst supported on the nanofibres, the spinning solution then can be prepared by heating this slurry.
BACKGROUND OF THE INVENTION.
Gel spinning processes are known and commercially practiced, for example those described in US 4 137 394, US 4 344 908 and US 5 342 567. In these processes a solution of high molecular weight of polyethylene ( a dope) in a suitable solvent is prepared. The molecular weight of the polyethylene is in the order of a million and more. The higher is the molecular weight of the polyethylene the stronger is the resultant fibre, however the higher is the molecular weight of the polyethylene the more difficult is to prepare the solution.
Polyethylene is soluble only at temperatures above some 120 C, thus the boiling point of the solvent must be higher than this temperature, otherwise it would flash during spinning, which is undesirable. Suitable solvents are pure or mixed hydrocarbons boiling in the range of 150-200 C or hydrocarbons having high boiling point such as mineral oils. Also fluorinated or chlorinated hydrocarbons may be used although this is not practiced in producing gel spun fibres. The polyethylene solution is spun and cooled so that the polyethylene gels, thus yielding a gel fibre of polyethylene containing solvent. To obtain the final product the fibre must be stretched to many times its original length and the solvent removed. The stretching is done at an appropriate temperature in one or multiple steps. The solvent is removed by extraction with a light solvent or it is evaporated or stripped by steam in the case that a volatile solvent is used. The sequence of stretching and solvent removal may follow each other by say solvent removal - stretching -stretching or stretching - solvent removal - stretching or by using a different sequence.
None of the prior art teaches the option of adding an insoluble fibres such as carbon nanotubes to the dope.
High molecular weight polyethylene is known and is commercially available under the name Hostalen GUR, for example.
Nanofibres are known. For example carbon nanotubes are available in research quantities and may soon be available in commercial quantities. Presently only one method for organizing these nanofibres into an oriented fibre is described in Science, 290, 1331 (2000). A dispersion of carbon nanotubes is spun into a stream of poly (vinyl alcohol) solution in water. The process is slow and it is not commercial.
DETAILED DESCRIPTION OF THE INVENTION.
I have now found a process for producing a continuous fibre from nanofilaments using a gel spinning process.
In the process of the invention the nanofibres are added to the solution of the high molecular weight polyethylene in a suitable spinning solvent.
The polyethylene is a linear "high density" polyethylene prepared by any known process.
Its molecular weight may be 100 000 to 10 000 000, preferably 500 000 to 4 000 000. A
polar monomer such as malefic anhydride may be grafted to the polyethylene backbone to provide enhanced bonding between the POLYETHYLENE and the nanofibres in the final product.
The nanofibres may be any fibres of a diameter in the order of 10 nm and of the length to diameter ration greater than 50, preferably greater than 100. Preferably single wall carbon nanotubes can be used.
The solvent may be a hydrocarbon or a similar solvent in which polyethylene is soluble, such as fluorinated or chlorinated hydrocarbon. A mixture of said solvents may be used.
The normal boiling point of the solvent is above the temperature at which polyethylene is soluble in the solvent which is about 120 C. The solvent selection depends on the particular gel spinning process. Lower boiling solvent are advantageously used when the solvent is evaporated from the gel after spinning while high boiling solvents such as mineral oil have to be extracted from the gel. Either process has its advantages and draw-backs, as those skilled in the art would appreciate.
In preparing the solution the nanofibres and the high molecular weight polyethylene can be added to the solvent and in a stirred tank and while stirring the temperature is increased to the desired level. Care must be taken to exclude oxygen. The vessel design and the dissolution procedures are described in the prior art and are well known to those skilled in the art. The molecular weight and concentration of the polyethylene and the concentration of nanofibres in the spinning solution are adjusted so that desired processability and content of the nanofibres in the final product are obtained.
Alternately, the fibre can be dispersed in a purified spinning solvent, and an ethylene polymerization catalyst is then deposited onto the nanofibres, the vessel is pressurized with ethylene which polymerizes and coats the nanofibres. The polymerization catalyst and the temperature are selected so that the resultant polyethylene is of the desired molecular weight. Upon heating to at least the solubilization temperature the polyethylene dissolves and the solution can be used as the spinning solution in the subsequent gel spinning process. This method may provide a more uniform dispersion of the nanofibres.
The temperature of spinning solution must be above the minimum temperature at which the polyethylene is soluble in the solvent used, which is usually 120- 130 C.
However the temperature should not be much higher than the normal boiling temperature of the solvent else it would flash at the spinneret exit which is undesirable.
The orientation of the nanofibres is the result of the shear gradient in the spinneret followed by the considerable reduction in the transverse dimension of the gel fibre caused by the solvent removal and drawing of the fibre. Thus for example a gel fibre spun from a dope which after cooling contains 5 volume % of the nanofibres and 5 volume %
of the polyethylene and drawn 20 times receives orientation similar to a melt spun fibre drawn 200 times.
Nanofibres may be added to the dope and converted to fibre using other solution spinning processes such as those used in the production of poly acrylo nitrile or celulose acetate fibres for example. Although the final orientation would be lower than that achieved in gel spun polyethylene fibres, the product may be quite suitable for some end uses.
There are potentially many uses for such fibres utilizing their strength or electrical properties. However the technology is too new to anticipate all the uses.
Claims (16)
1. A process for the production of a fibre in which nanofilaments are oriented along the fibre length, said process comprising spinning a solution of high molecular weight polyethylene in which the nanofilaments are dispersed, cooling the spun fibre to below the polyethylene solubilization temperature followed by removing the solvent and drawing the fibre.
2. The process of claim 1 in which the spinning solution is prepared by admixing high molecular weight polyethylene and the nanofilaments with solvent and heating the admixture to dissolve the polyethylene
3. The process of claim 1 in which the nanofibres are dispersed in the spinning solvent, an ethylene polymerization catalyst is deposited onto the nanofibres, then ethylene is introduced so that the polyethylene thus produced coats the nanofibres. When sufficient amount of polyethylene is produced, the unreacted ethylene is flashed off, the dispersion heated so that the polyethylene dissolves thus forming the spinning solution.
4. The process of claim 1 in which the solvent has the normal boiling point higher than 110 C.
5. The process of claim 5 in which the solvent has the normal boiling point higher than 200 C.
6. The process of claim 1 in which the solvent is removed from the fiber by evaporation in an inert atmosphere.
7. The process of claim 6 in which the inert atmosphere is steam.
8. The process of claim 1 in which the solvent is removed by extraction (washing) with an extraction solvent.
9. The process of claim 1 in which the diameter of the drawn fibre is smaller than the diameter of the spinning orifice by six or more times.
10. The process of claim 1 in which the fibre is drawn in one step.
11. The process of claim 1 in which the fibre is drawn in more steps.
12. The fibre produced by the process of claim 1.
13. The process of claim 1 in which the drawn fibre containing polyethylene and nanofibres it heated in an inert atmosphere to temperature higher than 300 C
so that the polyethylene cracks and evaporates thus leaving a fibre consisting essentially from the nanofibres.
so that the polyethylene cracks and evaporates thus leaving a fibre consisting essentially from the nanofibres.
14. A fibre consisting essentially from nanofibres produced by the process of claim 13.
15. The process of claim 1 in which the drawn fibre containing polyethylene and nanofibres it heated in an oxidizing atmosphere at temperature increasing from room temperature to a temperature higher than 300 C so that the polyethylene is converted to carbon, thus leaving a fibre consisting essentially from the nanofibres in a carbon matrix.
16. A fibre consisting essentially from the nanofibres in a carbon matrix, regardless of the process used for making such fibres.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2342151 CA2342151A1 (en) | 2001-02-22 | 2001-02-22 | Production of continuous fibre from nanofibres |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2342151 CA2342151A1 (en) | 2001-02-22 | 2001-02-22 | Production of continuous fibre from nanofibres |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2342151A1 true CA2342151A1 (en) | 2002-08-22 |
Family
ID=4168697
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2342151 Abandoned CA2342151A1 (en) | 2001-02-22 | 2001-02-22 | Production of continuous fibre from nanofibres |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2342151A1 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2009059387A1 (en) * | 2007-11-08 | 2009-05-14 | Braskem S. A. | Process for the production of high tensile strength and low creep polymer yarns, high tensile strength and low creep polymer or copolymer yarns, and, the use of such yarns |
| CN103249879A (en) * | 2010-10-05 | 2013-08-14 | 聚合物研发中心 | Process for producing high-performance polymer fibers |
-
2001
- 2001-02-22 CA CA 2342151 patent/CA2342151A1/en not_active Abandoned
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2009059387A1 (en) * | 2007-11-08 | 2009-05-14 | Braskem S. A. | Process for the production of high tensile strength and low creep polymer yarns, high tensile strength and low creep polymer or copolymer yarns, and, the use of such yarns |
| CN103249879A (en) * | 2010-10-05 | 2013-08-14 | 聚合物研发中心 | Process for producing high-performance polymer fibers |
| US20130241105A1 (en) * | 2010-10-05 | 2013-09-19 | Polymer Research & Development | Process for producing high-performance polymer fibers |
| US9205589B2 (en) * | 2010-10-05 | 2015-12-08 | Polymer Research & Development | Process for producing high-performance polymer fibers |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Dead |