JP2018517861A - Method for producing polyolefin fiber - Google Patents

Abstract

The present invention includes: a) preparing a solution of a polyolefin in a solvent; b) placing the resulting polyolefin solution in a fiber manufacturing apparatus that includes a body having one or more openings configured to receive the polyolefin solution; c) An average fiber comprising the steps of rotating a fiber manufacturing apparatus and manufacturing a polyolefin fiber having an average fiber diameter of 5000 nm or less by passing the polyolefin solution through the one or more openings by rotating the fiber manufacturing apparatus. A method for producing a polyolefin fiber having a diameter of 5000 nm or less, wherein the polyolefin comprises a polyethylene polymer and copolymer having a weight average molecular weight Mw of at least 40,000 daltons and a polypropylene polymer and copolymer having a weight average molecular weight Mw of at least 120,000 daltons. Selected from the fiber The present invention relates to a method of rotating a manufacturing apparatus at a speed of at least 10,000 revolutions per minute. The invention also relates to the polyolefin fiber and articles containing it.

Description

  The present invention relates to a process for producing polyolefin fibers, in particular polyethylene fibers, preferably nanofibers thereof. The present invention further relates to a polyolefin fiber obtained by the above method.

  There is an increasing need for very fine fibers and fiber webs made from very fine fibers. This type of web is useful in selective barrier applications of the final product. Nanofiber webs have found widespread use as scaffolds in filtration, membrane separation, military protective clothing, biosensors, wound dressings and tissue engineering.

  However, despite these possibilities, nanofibers have limited applications due to their weak mechanical properties.

  The most widely used spinning methods for making polymer fibers are the electrospinnin and melt blow spinning methods. Electrospinning is preferred for nano-sized fibers, but this method has several drawbacks, such as requiring high voltage electric fields, low production rates, and requiring accurate conductivity of the solution.

  Forcespinning, unlike electrospinning, does not require the material to have the necessary dielectric properties for processing, so the material that can be made into a fiber is not limited. Force spinning is a method in which a spinneret is rotated at high speed, and a jet of liquid material is ejected from an orifice by combining centrifugal force and hydrostatic pressure. When the jet of material exits the orifice, the material is drawn into nanofibers due to the aerodynamic environment and the inertia of the spinneret.

  To date, however, there have been few reports of successful production of polymeric nanofibers with excellent mechanical properties, especially polyolefin nanofibers such as polyethylene and polypropylene.

http://fiberiotech.com/products/forcespinning-products/

In view of the above, there is a need to develop other efficient processes for producing polyolefin nanofibers, particularly polyolefin nanofibers with improved mechanical properties.
The present invention provides one or more solutions to this need.

From the first aspect of the present invention, the present invention provides the following (a) to (c):
(A) preparing a polyolefin solution in a solvent;
(B) placing the resulting polyolefin solution into a fiber manufacturing apparatus comprising a body having one or more openings configured to receive the polyolefin solution;
(C) Rotating the fiber manufacturing apparatus, and by rotating the fiber manufacturing apparatus, the polyolefin solution is made into a polyolefin fiber having an average fiber diameter of 5000 nm or less through the one or more openings.
A process for producing a polyolefin fiber having an average fiber diameter of 5000 nm or less, comprising the steps of:
A method is provided wherein the polyolefin is selected from the group consisting of polyethylene polymers and copolymers having a weight average molecular weight Mw of at least 40,000 daltons and polypropylene polymers and copolymers having a weight average molecular weight Mw of at least 120,000 daltons. .

Preferably, the present invention provides the following (a) to (c):
(A) preparing a polyolefin solution in a solvent;
(B) placing the resulting polyolefin solution into a fiber manufacturing apparatus comprising a body having one or more openings configured to receive the polyolefin solution;
(C) Rotating the fiber manufacturing apparatus, and by rotating the fiber manufacturing apparatus, the polyolefin solution is made into a polyolefin fiber having an average fiber diameter of 5000 nm or less through the one or more openings.
A process for producing a polyolefin fiber having an average fiber diameter of 5000 nm or less, comprising the steps of:
The polyolefin is selected from the group consisting of polyethylene polymers and copolymers having a weight average molecular weight Mw of at least 40,000 daltons and polypropylene polymers and copolymers having a weight average molecular weight Mw of at least 120,000 daltons;
Rotating the fiber manufacturing apparatus at a speed of at least 10,000 revolutions per minute (rpm);
A method characterized by the above is provided.

  From the second aspect of the present invention, the present invention further includes a polyolefin fiber having an average fiber diameter of 5000 nm or less obtained by the above method according to the first aspect of the present invention.

  From a third aspect of the present invention, the present invention further includes a polyolefin fiber having an average fiber diameter of 5000 nm or less, wherein the polyolefin has a weight average molecular weight Mw of at least 40,000 daltons, and at least 120,000 daltons. Selected from the group consisting of polypropylene polymers and copolymers having a weight average molecular weight Mw of

  From a fourth aspect of the present invention, the present invention further encompasses an article comprising a polyolefin fiber according to the second or third aspect of the present invention or a polyolefin fiber produced by the method according to the first aspect of the present invention.

  Surprisingly, it has been found that by using the method of the present invention, it is possible to produce polyolefin fibers having an average fiber diameter of 5000 nm or less and excellent mechanical properties (tensile strength, elastic modulus and tenacity). It was issued.

Sectional schematic diagram of the fiber manufacturing apparatus used in Examples 1 and 2. FIG.

  The invention is further described below to define different aspects of the invention in more detail, but each aspect defined below is combined with any other aspect or aspect unless indicated to the contrary. be able to. In particular, any feature or statement indicated as being preferred or advantageous may be combined with any other feature or statement indicated as being preferred or advantageous.

  Prior to describing the fibers and articles encompassed by the present invention, it is understood that the present invention is not limited to the specific methods, fibers and articles described, and may be different fibers and articles. Should. The terminology used herein is not intended to be limiting. It should be understood that the scope of the present invention is limited only by the claims.

  All terms used in disclosing the present invention, unless otherwise defined, have the meanings of technical and scientific terms as commonly understood by one of ordinary skill in the art to which this invention belongs. The definitions of terms used in the following description also include guidelines for a better understanding of the teachings of the present invention. The terms used in the present invention when describing polymer resins, methods, articles and uses are to be interpreted according to the following definitions unless the context indicates otherwise.

  As used herein, the singular forms “a”, “an” include both the singular and plural unless the context clearly dictates otherwise. For example, “resin” means one resin or a plurality of resins.

  As used herein, the terms “consisting”, “composed”, and “including” are synonymous with “including”, “included”, or “containing”, “included” “including” is open-ended. It does not exclude additional components, components, elements or method steps. The terms “consisting of” and “consisting of” include “consisting of only” and “consisting of only”.

  The numerical range indicating the endpoint includes all integers contained in it, and also includes the decimal point included in it as appropriate (e.g. 1 to 5 is 1, 2, 3, 4 when referring to the number of elements). And 1.5, 2, 2.75 and 3.80 when referring to measurements). When the end point is described, the end point value itself is included (for example, 1.0 to 5.0 includes both 1.0 and 5.0). Any numerical range recited herein includes all subranges subsumed therein.

As used herein, “an embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. . Thus, in various places throughout the specification, “in one embodiment” or “in one embodiment” do not necessarily all refer to the same embodiment. Specific features, structures or characteristics may be combined in any suitable manner in one or more implementations that will be apparent to those skilled in the art from the disclosure herein. Some embodiments described herein may include other features included in other embodiments, and features of different embodiments may be combined to form different embodiments within the scope of the present invention. Those skilled in the art will understand that this is the case.
For example, all the embodiments can be used in any combination in the following claims and statements.

  Hereinafter, preferred statements and embodiments of the polymer resins, methods, articles and applications of the present invention are described. Each statement and embodiment of the invention as defined can be combined with other statements and / or embodiments unless clearly indicated to the contrary. In particular, any feature or statement indicated as being preferred or advantageous can be combined with any other feature or statement indicated as being preferred or advantageous. The present invention is particularly understood by any combination of statements and / or embodiments represented by the numbers 1-22 below with any other one or more statements and / or embodiments.

1. The following (a) to (c):
(A) preparing a polyolefin solution in a solvent;
(B) placing the resulting polyolefin solution into a fiber manufacturing apparatus comprising a body having one or more openings configured to receive the polyolefin solution;
(C) rotating the fiber manufacturing apparatus, and passing the polyolefin solution through the one or more openings by rotating the fiber manufacturing apparatus to manufacture a polyolefin fiber having an average fiber diameter of 5000 nm or less;
A process for producing a polyolefin fiber having an average fiber diameter of 5000 nm or less, comprising the steps of:
The polyolefin is selected from the group consisting of polyethylene polymers and copolymers having a weight average molecular weight Mw of at least 40,000 daltons and polypropylene polymers and copolymers having a weight average molecular weight Mw of at least 120,000 daltons,
A method characterized by that.

2. The following (a) to (c):
(A) preparing a polyolefin solution in a solvent;
(B) placing the resulting polyolefin solution into a fiber manufacturing apparatus comprising a body having one or more openings configured to receive the polyolefin solution;
(C) rotating the fiber manufacturing apparatus, and passing the polyolefin solution through the one or more openings by rotating the fiber manufacturing apparatus to manufacture a polyolefin fiber having an average fiber diameter of 5000 nm or less;
A process for producing a polyolefin fiber having an average fiber diameter of 5000 nm or less, comprising the steps of:
The polyolefin is selected from the group consisting of polyethylene polymers and copolymers having a weight average molecular weight Mw of at least 40,000 daltons and polypropylene polymers and copolymers having a weight average molecular weight Mw of at least 120,000 daltons;
Rotating the fiber manufacturing apparatus at a speed of at least 10,000 revolutions per minute (rpm);
A method characterized by that.

3. Method according to statement 1 or 2, wherein the fiber manufacturing apparatus is rotated at a speed of at least 10,000 RPM, preferably at least 15000 RPM, preferably at least 20000 RPM, preferably at least 22000 RPM.

4). 4. The method according to any one of statements 1 to 3, wherein the polyolefin is selected from the group comprising polyethylene polymers and copolymers having a weight average molecular weight Mw of at least 120,000 daltons and polypropylene polymers and copolymers.

5. The polyolefin is at least 200,000 daltons, preferably at least 300,000 daltons, preferably at least 400,000 daltons, preferably at least 500,000 daltons, preferably at least 600,000 daltons, preferably at least 700,000 daltons, preferably at least 800,000 daltons, preferably at least 900,000 daltons, 5. Process according to any one of statements 1 to 4, characterized in that it is preferably selected from the group consisting of polyethylene polymers and copolymers having a weight average molecular weight Mw of at least one 000000 dalton and polypropylene polymers and copolymers.

6). 6. The method according to any one of statements 1 to 5, wherein the polyethylene or polypropylene polymer used in the method of the present invention is a homopolymer.

7). The method according to any one of statements 1 to 6, wherein the polyethylene or polypropylene polymer is a linear polymer.
8). 8. The method according to any one of statements 1 to 7, wherein the molecular weight distribution of the polyethylene or polypropylene polymer is at most 10.

9. 9. Method according to any one of statements 1 to 8, characterized in that the molecular weight distribution of the polyethylene or polypropylene polymer is at least 5.

10. The molecular weight distribution of the polyethylene or polypropylene polymer is at least 5, and at most 10, preferably at least 6, and at most 10, preferably at least 7, and at most 9, as described in a statement according to any one of the preceding claims. the method of.

11. The method according to any one of statements 1 to 10, wherein the polyolefin is polyethylene.

12 The method according to any one of statements 1-1, wherein the polyolefin is ultra high molecular weight polyethylene (UHMWPE).

13. The method as described in any one of the statements 1-12 whose average diameter of the produced olefin fiber is 2000 nm or less, Preferably it is 1000 nm or less.

14 14. A method according to any one of statements 1 to 13, comprising heating the fiber production equipment to a temperature of at least 40C, preferably at least 100C, most preferably 200C.

15. 15. A method according to any one of statements 1 to 14, comprising the step of cooling the fiber.

16. 16. The method of any one of statements 1-15, further comprising collecting the fibers on a current collector to form a fiber web.

17. The method according to any one of statements 1 to 16, further comprising the step of removing the solvent from the fiber.

18. 18. Statements 1 to 17, wherein the polyolefin solution comprises at least 1% and at most 50% or less, preferably at least 5% and at most 20% by weight of polyolefin, based on the total weight of the polyolefin solution. Method.

19. Solvent is C6-C16 alcohol, fully saturated white mineral oil, vegetable oil, C4-C20 carboxylic acid, aliphatic and cycloaliphatic hydrocarbons, petroleum fraction, mineral oil, kerosene, hydrogenated derivative, halogenated hydrocarbon, cyclo 19. A method according to any one of statements 1 to 18 selected from the group comprising alkanes, cycloalkenes, aromatic hydrocarbons and terpenes.

20. The method according to any one of statements 1 to 19, wherein the diameter of the one or more openings is at least 2 mm, preferably at least 1 mm, preferably at least 0.5 mm, preferably at least 0.1 mm.

21. The polyolefin fiber whose average fiber diameter obtained by the method as described in any one of statements 1-20 is 5000 nm or less.

22. A polyolefin fiber having an average fiber diameter of 5000 nm or less, wherein the polyolefin is selected from the group consisting of polyethylene polymers and copolymers having a weight average molecular weight Mw of at least 40,000 daltons and polypropylene polymers and copolymers having an average molecular weight Mw of at least 120,000 daltons.

23. Statement 21 wherein the average fiber diameter is 5000 nm or less, wherein the polyolefin is selected from the group consisting of polyethylene polymers and copolymers having a weight average molecular weight Mw of at least 40,000 daltons and polypropylene polymers and copolymers having a weight average molecular weight Mw of at least 120,000 daltons The polyolefin fiber described in 1.

24. 24. The polyolefin fiber of any one of statements 21 to 23 in the form of a nonwoven web.

25. 25. The polyolefin fiber according to any one of statements 21 to 24, wherein the polyethylene or polypropylene polymer is a homopolymer.

26. The polyolefin fiber according to any one of statements 21 to 25, wherein the polyethylene or polypropylene polymer is a linear polymer.

27. 27. The polyolefin fiber according to any one of statements 21 to 26, wherein the molecular weight distribution of the polyethylene or polypropylene polymer is at most 10.

28. 28. The polyolefin fiber according to any one of statements 21 to 27, wherein the molecular weight distribution of the polyethylene or polypropylene polymer is at least 5.

29. 29. Polyolefin fibers according to any of statements 21 to 28, wherein the molecular weight distribution of the polyethylene or polypropylene polymer is at least 5 and at most 10, preferably at least 6 and at most 10, preferably at least 7 and at most 9.

30. 30. The polyolefin fiber according to any one of statements 21 to 29, wherein the polyolefin is polyethylene.

31. The polyolefin fiber according to any one of statements 21 to 30, wherein the polyolefin is UHMWPE.

32. 21. An article comprising a polyolefin fiber according to any one of statements 21 to 31 or a polyolefin fiber produced according to the method according to any one of statements 1 to 20.

  As used herein, the term “fiber” generally means one having a well-defined length or having a substantially continuous elongated structure.

  As used herein, the term “nanofiber” refers to a fiber having a number average diameter (similar cross-sectional dimensions for non-circular shapes) of about 1000 nm or less. For non-circular cross-section nanofibers, the term “diameter” as used herein means the maximum cross-sectional dimension.

  In the present invention, a spinning technology called force spinning is used, which is an apparatus for forming fibers using centrifugal spinning technology.

  Force spinning methods and apparatus are known to those skilled in the art, and the equipment is commercially available from equipment suppliers, such as FiberRio Technology (McAllen, Texas, USA) (http: / /fiberiotech.com/products/forcespinning-products/).

  Therefore, detailed description of force spinning is not necessary, so only a brief description will be given here.

  This force spinning releases the polymer solution from the fiber forming device. The fiber forming apparatus includes a body (eg, spinneret or spin disk) that propels the polyolefin solution into a fiber form by centrifugal force. Polyolefin fibers are produced by force spinning from a polyolefin solution through one or more openings in the body.

The method of the present invention comprises the following steps:
(A) preparing a polyolefin solution in a solvent;
(B) placing the resulting polyolefin solution into a fiber manufacturing apparatus comprising a body having one or more openings configured to receive the polyolefin solution;
(C) rotating the fiber manufacturing apparatus, and passing the polyolefin solution through the one or more openings by rotating the fiber manufacturing apparatus to manufacture a polyolefin fiber having an average fiber diameter of 5000 nm or less;
The polyolefin is selected from the group consisting of polyethylene polymers and copolymers having a weight average molecular weight Mw of at least 40,000 daltons and polypropylene polymers and copolymers having a weight average molecular weight Mw of at least 120,000 daltons, and the fiber production equipment is at a rate of at least 10,000 RPM It is rotated.

  The polyethylene suitable for use in the present invention can be a homopolymer of ethylene having a weight average molecular weight Mw of at least 40,000 daltons or a copolymer of ethylene and one or more optional comonomers, the comonomers being ethylene and Are selected, and those suitable for copolymerization with olefins are selected. Comonomers are C3-C20-α-olefins such as propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1 -It can be hexadecene, 1-octadecene or 1-eicosene. In a preferred embodiment, the polyethylene is a homopolymer.

  The polyethylene polymers and copolymers used in the present invention have a maximum melt flow index MI2 measured at 190 ° C. under ISO standard 1133 procedure B, condition D and a load of 2.16 kg, eg 34 g / 10 min. 30 g / 10 min at maximum, preferably 20 g / 10 min at maximum, preferably 10 g / 10 min at maximum, preferably 1 g / 10 min at maximum, preferably 0.1 g / 10 min at maximum.

  The polyethylene polymers and copolymers used in the present invention can be prepared by polymerizing ethylene with one or more optional comonomers in the presence of a catalyst system and optionally in the presence of hydrogen. As used herein, the term “catalyst” means a substance that changes the rate of a polymerization reaction. In the present invention, the catalyst is particularly applicable to a catalyst suitable for polymerizing propylene to polypropylene. In some embodiments, the catalyst is a chromium catalyst, a Ziegler-Natta catalyst, or a metallocene catalyst. In a preferred embodiment, the catalyst is a Ziegler-Natta catalyst.

  The polyethylene polymer used herein is a homopolymer, preferably a homopolymer with a low long chain branch content.

  The polyethylene is preferably ultra high molecular weight polyethylene (UHMWPE) having a molecular weight distribution of 10 at the maximum. Preferably, the molecular weight distribution of UHMWPE is at least 5, and the molecular weight distribution of UHMWPE is at least 5 and at most 10. The molecular weight distribution of UHMWPE is preferably at least 5 and at most 9. The molecular weight distribution of UHMWPE is preferably at least 6 and at most 9.

  Suitable polypropylene for use in the present invention can be a propylene homopolymer having a weight average molecular weight Mw of at least 120,000 daltons or a copolymer of propylene and one or more optional comonomers.

  Polypropylene may be a random copolymer. The one or more comonomers are selected from the group consisting of ethylene and C4-C10 alpha olefins such as 1-butene, 1-pentene, 1-hexene, 1-octene or 4-methyl-1-pentene. Preferred comonomers are ethylene and 1-butene. The most preferred comonomer is ethylene. Polypropylene can be a homopolymer of propylene.

  The melt flow index of polypropylene polymers and copolymers measured under ISO standard 1133, condition M at 230 ° C. under a load of 2.16 kg is a maximum of 32 g / 10 minutes, for example a maximum of 30 g / 10 minutes, preferably a maximum of 20 g / 10 minutes, preferably at most 10 g / 10 minutes, preferably at most 1 g / 10 minutes, preferably at most 0.1 g / 10 minutes.

  The polypropylene polymers and copolymers used in the present invention can be prepared by polymerizing propylene and one or more optional comonomer such as ethylene in the presence of a catalyst system and optionally in the presence of hydrogen. In some embodiments, the catalyst can be a chromium catalyst, a Ziegler-Natta catalyst, or a metallocene catalyst.

  The polyethylene or polypropylene polymer used in the method of the present invention preferably has an ultramolecular weight (UHMW). That is, the intrinsic viscosity (IV) measured with a decalin (decahydronaphthalene) solution at 135 ° C. according to ISO standard 1628-3 is at least 5 dl / g, preferably at least 10 dl / g, more preferably at least 15 dl / g. The intrinsic viscosity (IV) is preferably at most 40 dl / g, more preferably 30 dl / g.

  The UHMW polyolefin solution is preferably prepared at a concentration of at least 1% by weight. It is preferred that the UHMW polyolefin solution has a concentration of up to 50% by weight, preferably up to 30% by weight, more preferably up to 25% by weight, more preferably up to 20% by weight.

  Any known solvent suitable for forming a polyolefin gel can be used to prepare the polyolefin solution (or gel). In some embodiments, the solvent is a C6-C16 alcohol, a fully saturated white mineral oil; a vegetable oil selected from vegetable oils such as olive oil, peanut oil, palm oil, coconut oil, C4-C20 carboxylic acids such as butanoic acid, Contains pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, heptadecanoic acid, octadecanoic acid, nonadecanoic acid, and eicosanoic acid C4-C20 carboxylic acids selected from the group, aliphatic and alicyclic hydrocarbons and isomers thereof, for example aliphatic and alicyclic hydrocarbons selected from the group comprising octane, nonane, decane and paraffin; Mineral oil; kerosene; aromatic hydrocarbons such as toluene, xylene, and naphth Aromatic hydrocarbons containing hydrogenated derivatives such as decalin and tetralin selected from the group comprising len; halogenated hydrocarbons such as monochlorobenzene; cycloalkanes such as methylcyclopentane; cycloalkenes; eg camphene, p- It can be selected from the group consisting of terpenes such as menthane-3,8-diol, limonene and dipentene. Combinations of the above media may be used, and for the sake of simplicity, combinations of solvents are also referred to as solvents.

  In the most preferred embodiment, the solvent is white mineral oil, paraffin, decalin, nonan-2-ol (CAS 628-99-9), C9-C11 alcohol, eg (CAS 66455-17-2) or C10-16 alcohol (CAS 67762-41). Select from -8).

Compared to the analysis of pure polymer, the crystallization temperature must be reduced by at least 1 ° C. when analyzing the solution (gel) by DSC. The following procedure is used to determine this decrease in crystallization temperature.
(1) After calibrating the temperature with an indium sample (see thermal analysis of polymers, fundamentals and applications, edited by JD Menczel and RB Prime, John Wiley & Sons, Hoboken, New Jersey (2009)), polymer samples ( 2-10 mg) is placed in the DSC apparatus (Mettler Toledo, DSC1). Add the following thermal history: Stabilize the sample at 20 ° C for 4 minutes, heat to 220 ° C at 20 ° C / minute, stabilize the sample for 3 minutes at 220 ° C, cool to -20 ° C, at 20 ° C / minute Heat to 220 ° C. for 3 minutes.
The crystallization temperature is determined during the cooling step. The temperature at the peak end after subtracting the baseline (the straight line drawn between the start of the crystallization peak close to 130 ° C. and 20 ° C.) is taken as the crystallization temperature.
(2) Repeat the above procedure with gel. The difference between the crystallization temperature of the pure polymer and that in solution (gel) can be calculated.

  In step (b) of the method of the present invention, the polyolefin solution is put into a fiber production apparatus. The fiber manufacturing apparatus has a body configured to receive a polyolefin solution, the body having one or more openings. In step (c) of the method of the present invention, the fiber manufacturing apparatus is rotated. When the fiber manufacturing apparatus rotates, the polyolefin solution passes through the openings and polyolefin fibers having an average fiber diameter of 5000 nanometers or less are manufactured.

  In some embodiments, the fiber maker includes a spinneret having a reservoir configured to contain a polyolefin solution. During operation, the spinneret rotates at a high speed on the axis every minute, and hydrostatic pressure and centrifugal force are created by centrifugal rotation. The polyolefin solution is extruded from the outer wall having at least one opening (orifice) by hydrostatic pressure and centrifugal force generated by the rotation of the spinneret. The polyolefin solution entering one or more openings is released and the centrifugal force and hydrostatic force combine to create a jet of the polyolefin solution that impinges on the fiber collector to produce a fiber.

  The polyolefin solution is discharged as a jet of material into the ambient atmosphere from one or more openings (orifices) by rotation. The one or more openings and associated channel feed openings can be sized and shaped to produce a fine jet of polyolefin solution. As used herein, an opening means the addition of an exit orifice and any associated channels or supply passages that can define the properties of the polyolefin solution jet. The openings can be of various shapes (eg, circular, oval, rectangular, square) of various diameters and sizes. When a plurality of openings are used, all the openings are not necessarily the same, and may be different openings. In certain embodiments, all the openings have the same configuration. Each opening has a diameter of at most 2 mm, preferably 1 mm or less, more preferably 0.5 mm or less, for example 0.1 mm at maximum. As used herein, the diameter of the opening means the effective diameter. That is, for non-circular or irregularly shaped openings, it means the maximum distance between the outer boundaries of the openings.

  The discharged material solidifies as ultrafine fibers having a diameter that is significantly smaller than the inner diameter of the outlet port.

  The fiber production equipment rotates at a speed of at least 10,000 revolutions per minute (rpm). Some embodiments rotate at a speed of at least 15000 RPM per minute. Other embodiments rotate at at least 20000 RPM per minute. In other embodiments, it rotates at at least 22000 RPM. The speed of the fiber manufacturing device can be constant while the fiber manufacturing device rotates, but the rotation of the fiber manufacturing device can also be adjusted.

  If desired, the temperature of the rotating body during fiber spinning may be controlled. For example, the temperature of the rotating body can be adjusted to about 40 ° C. or higher, preferably in the range of about 100 ° C. to about 200 ° C.

  The fibers are distributed radially from the rotating member during centrifugal spinning and discharged onto the collection surface. As used herein, “recovering” a fiber means that the fiber abuts on a fiber recovery device or collector. After the fibers are collected, the fibers can be removed from the fiber collection device by humans, robots, conveyor belts, or by gravity or other methods. Various methods and fiber recovery devices can be used to recover the fibers (eg, nanofibers).

  The fibers can be discharged, for example, from a spinneret on a surface located on the wall below the spinneret or on the wall across the outlet port of the spinneret. The collection surface can be varied as required and can be stationary or rotating during fiber collection. In one embodiment, for example, the collection surface can be provided on a collection wall surrounding the rotating member.

  The recovered fiber material can also be in the form of a web entangled in two or three dimensions. The web can be processed to the desired surface area and thickness as a function of the time it is being discharged onto the collector and by controlling the surface area.

  Thereafter, the polyolefin fibers are preferably cooled. In some embodiments, the temperature at which the polyolefin fibers are cooled is at most 100 ° C, more preferably at most 80 ° C, most preferably at most 60 ° C. The temperature for cooling the polyolefin fibers is preferably at least 1 ° C, more preferably at least 5 ° C, even more preferably at least 10 ° C, and most preferably at least 15 ° C.

  Regardless of the particular technique used, the solvent can be removed from the fiber during and / or after spinning. To remove the solvent, the fiber (or fiber web) can simply be washed, dried and / or heated. That is, the solvent can be removed by evaporation, washing or other techniques.

  After the formation of the polyolefin fibers, the polyolefin fibers are sent to a solvent removal step where the solvent is at least partially removed to form solid polyolefin fibers from the polyolefin fibers.

  The solvent removal step is a known method, for example, by using a relatively volatile solvent such as decalin when preparing a polyolefin solution, evaporating, or when using mineral oil, using an extract such as cyclohexane. Can be executed. A combination of both methods can also be used. A suitable extract depends on the solvent. The extract is a liquid that does not cause a significant change in the polyolefin network structure of the polyolefin gel fiber. For example, cyclohexane, ethanol, ether, acetone, cyclohexanone, 2-methylpentanone, n-hexane, dichloromethane, trichlorotrifluoroethane, diethyl It can be ether, dioxane or a mixture thereof. It is preferable to select an extract that can be recycled after separating the solvent from the extract.

  In a preferred embodiment, the fibers are placed in a vacuum oven to remove residual solvent remaining on the polyolefin fibers of the present invention at temperatures of up to 148 ° C, more preferably up to 145 ° C, and most preferably up to 135 ° C. The vacuum oven is preferably maintained at a temperature of at least 50 ° C, preferably at least 20 ° C. More preferably, the removal of residual solvent is carried out with the fibers kept taut and thus without the fibers becoming loose.

  The amount of residual solvent remaining in the solid polyolefin fiber after the extraction step can vary within a large range, but the amount of solvent residue is preferably low. A preferred residual solvent amount is at most 15%, preferably at most 10%, more preferably at most 5%, more preferably at most 1% by weight of the initial amount of solvent in the polyolefin solution. The polyolefin fiber at the end of the solvent removal step preferably contains a solvent in an amount of 800 ppm or less by mass. More preferably, the amount of solvent is 600 mass ppm or less, preferably 100 mass ppm or less, and even more preferably 300 mass ppm or less.

  For recovered fibers, in certain embodiments, at least a portion of the recovered fibers are continuous, discontinuous, matte, woven, non-woven, or a mixture of these structures. The fibers can be formed into a two-dimensional or three-dimensional web, i.e., a mat, film or membrane.

  Fibers produced using the devices and methods described herein can be used in a variety of applications. Common areas that can be used include food, materials, electricity, defense, tissue engineering, biotechnology, medical devices, energy, alternative energy (eg, solar, wind, nuclear, hydraulic energy), medicine, drug delivery (eg, Improved drug solubility, drug encapsulation), textiles / textiles, nonwoven materials, filtration (eg, air, water, fuel, semiconductor, biomedical, etc.), automobiles, sports, aviation, space, energy transfer, paper, substrates, Includes but is not limited to hygiene materials, cosmetics, construction, apparel, packaging, geotextiles, thermal insulation and sound insulation.

  Some products that can be formed using the polyolefin fibers of the present invention include filters; wound dressings; cell growth substrates or scaffolds, battery separators. Sutures; chemical sensors, water and stain resistant textiles / fibers, odor resistant products, insulation, self-cleaning, penetration resistance, antibacterial properties, porosity / breathing, tear resistance, abrasion resistant fabrics; Energy-absorbing materials to protect, building reinforcements; tissue engineering substrates; tissue engineering petri dishes, filters for pharmaceutical production, functional filters for dip filters, hydrophobic materials for textiles such as textiles. Buildings, adhesives to increase durability, flexibility and airtightness; tapes; epoxy resins; glues, adsorbing materials; diaper media, mattress covers, acoustic materials; including liquid, gas, chemical or air filters However, it is not limited to these.

  The method of the present invention has the advantage of not having the disadvantages of conventional electrospinning. For example, the polarity of the gel does not necessarily need to be considered, and the solvent used is not so limited. The average fiber diameter of the obtained polyolefin fiber is 5000 nanometers or less.

  Examples of mechanical properties obtained in the present invention are tensile strength, elastic modulus, breaking force, elongation at break and the like.

  The following examples are merely illustrative of the invention and should not be construed as limiting the scope of the invention. While the form of the invention is illustrated by several examples, it will be apparent to those skilled in the art that the invention is not limited thereto and that various changes and modifications can be made without departing from the scope of the invention. I will.

Test Methods The properties and properties described above and in the following non-limiting examples were measured using the following test methods.
Except for polymers with very high mass and therefore poor solubility (eg, UHMWPE), molecular weights [(M _n (number average molecular weight), M _W (weight average molecular weight), M _Z (Z average molecular weight)) are size exclusion chromatography. (SEC), in particular gel permeation chromatography (GPC). Briefly, GPC-IR5 from Polymer Char is used and a 10 mg polyethylene sample is dissolved in 10 ml chlorobenzene at 160 ° C. for 1 hour. Injection volume: 400 μl, automatic sample preparation, injection temperature: about 160 ° C., column temperature: 145 ° C., detector temperature: 160 ° C. Two Shodex AT-806MS (Showa Denko) and one Styragel HT6E (Waters) column are used. Flow rate: 1 ml / min, Detector: Infrared detector (2800 to 3000 cm ⁻¹ ), Calibration: Polystyrene narrow standard polystyrene (PS) (commercially available), molecular weight M of each fraction i of eluted polyethylene is Mark-Horwink relationship Calculated by the formula (logio (M _PE ) = 0.965909 x logio (M _PS )-0.28264) (M _PE = cut at the low molecular weight end of 1000)

The molecular weight averages used to determine the relationship of molecular weight properties are number average molecular weight (M _N ), weight average molecular weight ( _{W of} M) and Z average molecular weight (M _Z ). These average molecular weights are defined by the following formula and are determined from the calculated Mi.

（ここで、ＮｉおよびＷｉは分子量Ｍｉを有する分子のそれぞれ数および重量である）

(Where Ni and Wi are the number and weight of each molecule having a molecular weight Mi)

  The third term (the rightmost term) in each case defines a method for obtaining these average values from the SEC chromatogram. Here, hi is the height (from the baseline) of the i-th elution fraction in the SEC curve, and Mi is the molecular weight of the species eluting in this increment.

Measurement of molecular weight distribution of UHMWPE The molecular weight distribution of UHMWPE was measured by quantifying the transition region between Newtonian viscosity and power-law domain. This transition is known to be related to both the molecular weight distribution and the long chain branch content in the polymer. The polyethylene chain used in the examples (UHMWPEGUR® 4113) has zero or at least very low long chain branching content. Thus, the transition can be related to the molecular weight distribution.

The rheology was measured at 230 ° C. using an ARES instrument (TA Instruments) in a frequency ω range of 0.05 to 50 rad / s (three frequencies analyzed per frequency decade). The applied strain is 0.5% (to maintain a linear viscoelastic domain).
(1) When the temperature (230 ° C) is reached, a stabilization time of about 3 hours is given before starting the measurement (a very long stabilization time in the case of manufacturing a polymer disk used in an ARES device). Is required, 5000 ppm Irganox B215 is premixed in the UHMWPE fluff).

  The rheological data is then fitted using the Carreau-Yasuda equation (see below). In this equation, “n” is “0”, and “a” is a parameter that quantifies the transition region between Newtonian viscosity and the power-law domain. The greater the “a”, the narrower the relaxation spectrum (the molecular weight distribution is narrower if there are no long chain branches in the polymer).

(2) Conformance parameters for UHMWPEGUR® 4113 are as follows:

In the case of UHMW polyethylene, the molecular weight was determined by measuring the intrinsic viscosity (IV, unit: dl / g) at 135 ° C. in decalin. This allows the viscosity molecular weight average (MV) to be calculated using the Margolies≡ formula: MV (kilodalton) = 53.7 ^* (IV) ^1.49 ).

  When the fiber diameter was 4 μm or more, the fiber diameter was measured using optical microscopy. For smaller diameters, a scanning electron microscope (SEM) was used.

Measurement of fiber diameter with an optical microscope:
Five fiber segments were fixed on flat glass and placed in a Leica DMLP microscope connected to a JVC camera using an “X40” lens. Images of 5 fibers were recorded and analyzed using Leica IM500 software. The fiber diameter was determined by comparison with an image of a reference value (an image of certified gradient glass previously recorded using the same lens). The average of 5 diameter measurements was reported.

  In the SEM microscope measurement, a bundle containing a plurality of fibers was introduced vertically into a capsule and sealed in an epoxy resin. After the resin had hardened after 24 hours, the bundle + epoxy sample was cut transverse to the fiber axis (using a milling machine with diamonds). The surface thus obtained was treated with carbon (metallization).

SEM images were taken from retrodiffused electrons. This SEM image gives a chemical contrast between the resin and fiber used in the encapsulation process. The measurement was performed using image processing software. For details of SEM measurement, refer to the following reference materials.
"Preparation des echantillons pour MEB et Microanalyse"-Philippe Jonnard (GNMEBA)-EDP Sciences `` Polymer Microscopy ''-Linda C. Sawyer, David T. Grubb and Gregory F. Meyers-Ed. Chaoman and Hall.

The equipment used [FIG. 1] is a schematic cross-sectional view of the fiber manufacturing apparatus used in Example 1 and Example 2. FIG. The fiber manufacturing apparatus includes a spinneret 1. The spinneret 1 is mechanically connected to a motor 2, and the motor 2 rotates the spinneret 1 through a shaft 5 so as to make a circular motion. The speed of the motor 2 can be adjusted from 10000 to 22000 RPM with an increment of 2000 RPM. The motor 2 is fixed to a strong frame 3, and a circular collector 4 having a diameter of 56 cm is concentric with the axis of the spinneret 1. The spinneret 1 has a stainless steel cell 7 which is closed with a threaded lid 6 and two orifices are formed on the diametrically opposite side of the bottom of the cell 7, each calibrated. A screw 8 having a bore with a diameter of 0.5 mm is screwed. The shaft 5 is screwed to the lid 6 so that it can be attached to the mandrel of the motor 2. The outer dimensions of the cell 7 are 29.96 mm in diameter and 35.40 mm in height. The internal dimensions of the cell 7 are 20.80 mm in diameter and 11.13 mm in height.

Example 1
0.52 g of UHMWPE (GUR® 4113 commercially available from Ticona: powdered linear polyethylene, Margolie's formula (M _v (kilodalton) = 53.7 IV ^1.49 ) has a molecular weight of about 3.9 MGg / mol, the intrinsic viscosity (IV, dl / g) measured according to ISO standard 1628-3 was about 17.90 and the molecular weight distribution range measured according to the above method was 7-9] was mixed with 10 g of nonan-2-ol. The resulting mixture was placed in a 180 ° C. oven and mixed regularly. A gel gradually formed.
After the uniform gel was formed, a part of the hot gel was quickly put into the fiber manufacturing apparatus shown in FIG. The spinneret 1 was then rotated at 16000 RPM and the fiber was collected on the collector 4 The measured average fiber diameter was 3.5 μm.

Example 2
The procedure described in Example 1 was repeated, but the spinneret 1 rotation speed was 22000 RPM. The measured average fiber diameter value was 0.9 μm.

Claims (14)

The following (a) to (c):
(A) preparing a polyolefin solution in a solvent;
(B) placing the resulting polyolefin solution into a fiber manufacturing apparatus comprising a body having one or more openings configured to receive the polyolefin solution;
(C) Rotating the fiber manufacturing apparatus, and by rotating the fiber manufacturing apparatus, the polyolefin solution is passed through the one or more openings to form a polyolefin fiber having an average fiber diameter of 5000 nm or less.
A process for producing a polyolefin fiber having an average fiber diameter of 5000 nm or less, comprising the steps of:
The polyolefin is selected from the group consisting of polyethylene polymers and copolymers having a weight average molecular weight Mw of at least 40,000 daltons and polypropylene polymers and copolymers having a weight average molecular weight Mw of at least 120,000 daltons;
Rotating the fiber manufacturing apparatus at a speed of at least 10,000 revolutions per minute (rpm);
A method characterized by that.   The process according to claim 1, wherein the polyolefin is selected from the group comprising polyethylene polymers and copolymers having a weight average molecular weight Mw of at least 120,000 daltons and polypropylene polymers and copolymers.   The process according to claim 1 or 2, wherein the produced polyolefin fibers have an average fiber diameter of 2000 nm or less.   4. The polyolefin solution according to any one of claims 1 to 3, wherein the polyolefin solution comprises at least 1 wt% and at most 50 wt%, preferably at least 5 wt% and at most 20 wt% of polyolefin, based on the total weight of the polyolefin solution. The method described.   C6-C16 alcohol, fully saturated white mineral oil, vegetable oil, C4-C20 carboxylic acid, aliphatic and alicyclic hydrocarbons, petroleum fraction, mineral oil, kerosene, aromatic hydrocarbons and hydrogenated derivatives thereof, halogenated solvents 5. A process according to any one of claims 1 to 4 selected from the group comprising hydrocarbons, cycloalkanes, cycloalkenes and terpenes.   6. A method according to any one of the preceding claims, wherein the one or more openings have at least one diameter of at least 2 mm, preferably at least 1 mm, preferably at least 0.5 mm, preferably at least 0.1 mm. .   The method according to claim 1, wherein the polyolefin is polyethylene.   The method according to claim 1, wherein the polyolefin is UHMWPE.   The polyolefin fiber whose average fiber diameter obtained by the method as described in any one of Claims 1-8 is 5000 nm or less.   The average fiber diameter selected from the group wherein the polyolefin comprises a polyethylene polymer and copolymer having a weight average molecular weight Mw of at least 40,000 daltons and a polypropylene polymer and copolymer having a weight average molecular weight Mw of at least 120,000 daltons is 5000 nm or less. The polyolefin fiber according to 9.   11. A polyolefin fiber according to claim 9 or 10 in the form of a nonwoven web.   The polyolefin fiber according to any one of claims 9 to 11, wherein the polyolefin is polyethylene.   The polyolefin fiber according to any one of claims 9 to 12, wherein the polyolefin is UHMWPE.   An article comprising the polyolefin fiber according to any one of claims 9 to 13 or the polyolefin fiber produced by the method according to any one of claims 1 to 8.

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