JPH0641810A - Production of polyolefinic three-dimensional fiber - Google Patents

Abstract

PURPOSE:To produce polyolefinic three-dimensional fiber, excellent in strength and opening properties and suitable for producing a flash spun nonwoven fabric sheet by using a single noncombustible halogen-based solvent having low ability to destroy the ozonosphere. CONSTITUTION:The objective method for producing polyolefinic three- dimensional fiber is characterized by selecting a solvent from the group consisting of 1,2-dichloro-1,2-difluoroethylene, 1,1-dichloro-2,2-difluoroethylene,1,2- dichloro-1-fluoroethylene and 1,1-dichloro-2-fluoroethylene for a polyolefinic solution and regulating the polyolefinic concentration in the polyolefinic solution to 5-25wt.% in a method for producing the fibrillated polyolefinic three- dimensional fiber by passing the polyolefinic solution prepared at a high temperature under a high pressure through a vacuum orifice, a vacuum chamber and a spinneret and releasing the resultant solution to a zone at ordinary temperature under atmospheric pressure.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a polyolefin three-dimensional fiber using a solvent which is nonflammable and can be used very safely. More specifically, the present invention relates to a method for producing a three-dimensional fiber of a polyolefin having excellent strength and openability, which is used for a non-woven fabric sheet by using a solvent having a low ozone depleting ability.

[0002]

2. Description of the Related Art A method for producing a three-dimensional polyolefin fiber is known as a flash spinning method. In this flash spinning method, polyolefin is added to an organic solvent which can be said to be a liquefied gas, a polyolefin solution is prepared under high temperature and high pressure, and after that, the solution pressure is once reduced through a decompression orifice to cause phase separation, resulting in opacity. This is a method in which the solution is further jetted through a spinneret into an atmosphere at room temperature and normal pressure to form a three-dimensional fiber, which is a well-known spinning method.

For example, this spinning method is described in US Pat.
81519 (1963), U.S. Pat. No. 3,227.
794 (1966), U.S. Pat. No. 322778.
4 (1966), U.S. Pat. No. 3,467,744 (1969), U.S. Pat. No. 3,564,088 (1971), U.S. Pat. No. 3,756,411 (1973), European Patent Application Publication No. 285670A1 (1988), European Patent Application Publication No. 321567.
A1 specification (1989), European Patent Application Publication No. 357.
364A2 Specification (1990), Japanese Examined Patent Publication No. 40-281
No. 25, Japanese Patent Publication No. 42-19520, Japanese Patent Laid-Open No. Sho 6
It is described in JP-A-2-33816, JP-A-63-50512, and the like.

Fibers obtained by this flash spinning include short fibrous substances and continuous three-dimensional fibrous substances,
The former is used as synthetic pulp, and the latter is intended for three-dimensional fibers to be a non-woven sheet. This non-woven sheet is generally called synthetic paper,
The main characteristic of the product is that it is highly water resistant, strong, light and non-fluffy.

This is highly evaluated in the world, and this non-woven fabric sheet includes an air mail envelope, a floppy disk sleeve, an oxygen absorber bag, a desiccant bag, a medical sterilization bag, a building heat insulation dew condensation prevention cloth, a reactor power generation work clothes. It is also applied to asbestos workwear and safety workwear. In order to manufacture a product having these characteristics, a three-dimensional fiber having high strength and well opened is essential. This is because a dense, breathable and uniform sheet cannot be obtained without such fibers.

As a product of such a non-woven sheet,
The trademark Tyvek manufactured by DuPont, USA and the trademark Luxer manufactured by the present applicant are already commercially available. By the way, the solvent of the polymer used in the flash spinning method is required to have the following properties, which is already known in US Pat. No. 30,815,19 (1963) and the like.

That is, the boiling point of the solvent is at least 25 ° C. lower than the melting point of the polymer used, the solvent is inert to the polymer under spinning conditions, and the temperature and pressure are suitable for preparing the polymer solution. Then, it is a good solvent for the polymer, is a solvent that dissolves only 1% or less of the polymer at the boiling point of the solvent or less, and is a solvent capable of phase-separating immediately at the time of spinning to form a phase consisting of almost the polymer, In addition, it is a solvent that hardly remains in the separated polymer phase.

Specific examples of the solvent include aromatic hydrocarbons such as benzene and toluene, aliphatic hydrocarbons such as butane, pentane, hexane, heptane and octane, and their isomers, homologues and fats such as cyclohexane. Aromatic hydrocarbons, unsaturated hydrocarbons, halogenated hydrocarbons such as methylene chloride, carbon tetrachloride, chloroform, ethyl chloride and methyl chloride, alcohols such as ethanol, methanol and hexafluoroisopropanol, esters, ethers, ketones, Chlorinated fluorinated aliphatic hydrocarbons such as nitrile, amide, trichlorofluoromethane, 1,1,2-trichloro-1,2,2-trifluoroethane, sulfur dioxide, carbon disulfide, nitromethane, water and the above various Liquid mixtures and the like are known.

The solvent for the polymer used in the flash spinning method is appropriately selected from these solvents in consideration of various conditions of the spinning method and the kind of the polymer. In particular, as a solvent for the flash spinning method of polyolefin, it has excellent polymer solubility and excellent spinnability, and is also nonflammable and nontoxic trichlorofluoromethane,
1,1,2-Trichloro-1,2,2-trifluoroethane is preferred. In particular, trichlorofluoromethane is the most excellent solvent.

In flash spinning, the solvent must be at least low toxic and flame-retardant in order to eject the polymer solution under high temperature and high pressure into the atmosphere for gasification. In addition, it is required that the solvent has a low boiling point, is not thermally decomposed even at a high temperature, and is lipophilic enough to dissolve the polyolefin. The best solvent satisfying such conditions is the above-mentioned trichlorofluoromethane, and at present, no solvent surpassing this is found.

A large number of hydrocarbons or halogenated hydrocarbons have been disclosed as solvents for flash spinning. In flash spinning, the solvent is gasified and separated from the polymer, and the gasified solvent is recovered and liquefied by an operation such as cooling and compression. Therefore, flash spinning is performed in a vast enclosed space. This is because otherwise the gasified solvent cannot be recovered. The size of the closed space is, for example, 2000 m ³ .

Further, usually, a corona discharge device or a high-voltage static eliminator is built in this closed space and can serve as an ignition source for combustible gas. Therefore, to fill such a huge space with combustible gas is a fire,
Since the possibility of explosion and the like is extremely increased, it is extremely dangerous, and flammable gas cannot be practically used as a solvent.

Recently, it has been discovered that all halogenated hydrocarbons in which all hydrogen is replaced by chlorine and fluorine have extremely high ozone depletion ability as specific CFCs (also referred to as chlorofluorocarbons or CFCs). From the standpoint of protection, production was banned by the year 2000. Naturally, the production of specific fluorocarbons such as trichlorofluoromethane and 1,1,2-trichloro-1,2,2-trifluoroethane is also prohibited and cannot be obtained. Therefore, trichlorofluoromethane cannot be used as a solvent for the flash spinning method of polyolefin.

[0014] Against this background, a flash spinning method using a new solvent without using trichlorofluoromethane which is a specific flon has already been proposed. That is, US Pat. No. 5,032,326 (1991),
European Patent Application Publication No. 0357381A2 (19
89), JP-A-2-139408, methylene chloride and alternative fluorocarbons such as chlorofluoromethane, 1,
A flash spinning method using a mixed solvent of 1,1,2-tetrafluoroethane, 1,1-difluoroethane, 1,1,1,2-tetrafluoro-2-chloroethane, 1-chloro-1,1-difluoroethane, etc. It is disclosed.

US Pat. No. 5,081,177 (1992) and US Pat. No. 5,023,025 (1)
991), EP-A-0361684A1 (1990), and JP-A-2-160909, 1,1-dichloro-2,2,2-trifluoroethane, 1,2-dichloro-1, 2,2-trifluoroethane, 1,1-dichloro-2,2-difluoroethane, 1,
A spinning method using 2-dichloro-1,1-difluoroethane, 1,1-dichloro-1-fluoroethane, or the like is further described in European Patent Application Publication No. 0407953A2 (1991) with respect to polypropylene. A method of spinning using 1-dichloro-2,2,2-trifluoroethane, 1,2-dichloro-1,2,2-trifluoroethane, and further, European Patent Application Publication No. 357364A2.
The specification (1990) and Japanese Patent Laid-Open No. 3-76809 propose a spinning method using methylene chloride and carbon dioxide. Also, European Patent Application Publication No. 0414
498A2 Specification (1991), JP-A-3-1522
Japanese Patent Publication No. 09 proposes a method using a mixed solvent system of water-containing organic solvents.

Further, European Patent No. 431801 (1991) proposes a spinning method using carbon dioxide and water. However, all of these already proposed flash spinning methods have problems when spinning with polyolefins. For example,
In the mixed solvent of methylene chloride and alternative CFCs proposed by US Pat. No. 5,032,326 (1991), etc.,
The use of a low boiling point gas as a cosolvent complicates the manufacturing process. Further, there is a problem in using methylene chloride in view of the characteristics required for the solvent during spinning. The heat of vaporization of methylene chloride is 78.7 cal / g, which is much higher than that of trichlorofluoromethane of 43.5 cal / g. This means that when methylene chloride is used as the solvent, the solvent remains in the spun fiber flash-spun,
Means easy to get wet. Wet fibers are disclosed in JP-A-3-
As pointed out in Japanese Patent No. 76809, since a fiber is attached to the periphery of a roller used for hardening a sheet structure and tends to be wrapped around, a nonwoven fabric sheet having a commercial value cannot be obtained, and thus commercial I can't produce.

Therefore, when methylene chloride is used as a solvent, a gas having a low boiling point is allowed to coexist to promote the evaporation of methylene chloride remaining in the fiber after spinning, and at the same time, the polymer concentration of the spinning solution is adjusted in advance. It is necessary to raise it. Increasing the polymer concentration is effective in increasing the coagulation heat generation amount of the polymer when flushing the polymer solution and utilizing the heat to accelerate the drying of the spun fiber.

In this case, if either the use of the low boiling point gas or the increase of the polymer concentration is lacking, a wet fiber will result. However, when the concentration of the polymer in the spinning solution is increased, the opened state of the obtained fiber is deteriorated, and the quality of the sheet product tends to be deteriorated. Therefore, it is understood that methylene chloride cannot be used from the viewpoint of such spinnability.

There is also a problem with the proposal using alternative CFCs such as US Pat. No. 5,081,177 (1992). It is known that 1,1-dichloro-2,2,2-trifluoroethane and its isomers have an ozone depleting ability at a low level, and may be regulated as an ozone depleting substance in the near future. high. Therefore, such a solvent cannot be a substitute solvent for trichlorofluoromethane that can be used forever.

Further, since these CFC substitutes are poor solvents for high-density polyethylene, which is a typical example of polyolefin, there is another problem that high-density polyethylene cannot be dissolved when used alone. Therefore, in order to improve the solubility, a technique of using hydrocarbon, methylene chloride or the like as a cosolvent has been disclosed at the same time. However,
Even if hydrocarbons and methylene chloride coexist, since the ratio of CFC substitutes in the solvent is still high at 50% or more, the influence of these CFC substitutes on the poor solvent of high-density polyethylene remains strong. However, there is a problem that it is difficult to dissolve high-density polyethylene and the dissolution rate is slow.

Further, in this case as well, two kinds of solvents must be used, which complicates the manufacturing process. Similarly, 1,1-dichloro-2,2-difluoroethane and its isomers also have problems in ozone layer depleting ability and solubility of high-density polyethylene. On the other hand, 1,1-dichloro-
1-Fluoroethane and its isomers dissolve high-density polyethylene and give good quality fibers even when used alone. However, these solvents are very susceptible to thermal decomposition,
Even if it is rapidly dissolved by an extruder, it easily releases a large amount of hydrogen chloride or hydrogen fluoride and is thermally decomposed to easily generate a halogenated oligomer.

These decomposed products color the product,
It causes serious problems such as corrosion of spinning equipment. Further, with respect to 1,1-dichloro-1-fluoroethane, this solvent has a high ozone layer depletion ability, which is as high as about 1/10 of that of trichlorofluoromethane, and there is a problem that it has a high ozone layer depletion ability. Therefore, 1,1-dichloro-1-fluoroethane and its isomers cannot be used as a flash spinning solvent because they are easily decomposed by heat and have a high ozone depleting ability.

The technique proposed in EP-A-357364A2 (1990) cannot be used for the reasons already mentioned because it uses methylene chloride as a solvent. In addition, European Patent No. 431801 (199
The method of flash spinning using carbon dioxide and water as a solvent proposed in 1) can be applied to a specific polyolefin having vinyl alcohol, which is rich in hydrophilicity, as a copolymerization component.

However, since this solvent has a poor ability to dissolve general polyethylene and polypropylene,
It is almost impossible to obtain fibers having desirable physical properties. Moreover, in this method, it is necessary to use a surfactant substantially in combination, which not only complicates the process, but also causes a problem that the surfactant remains in the obtained fiber and practical properties are deteriorated. There is.

Furthermore, European Patent Application Publication No. 04144
Proposals using mixed systems of water-containing organic solvents such as 98A2 (1991) cannot be used because the solvent used has high flammability. From the above, it is clear that the trichlorofluoromethane alternative solvents for flash spinning that have been proposed so far all have unsolved problems, and they are still sufficiently satisfactory to substitute trichlorofluoromethane. No possible solvent has been proposed.

[0026]

The object of the present invention is to:
Excellent as a solvent for flash spinning of polyolefins,
Another object of the present invention is to provide a method for producing a three-dimensional fiber using a solvent which is hard to burn and has a low ozone depleting ability and which can substitute for trichlorofluoromethane. Still another object of the present invention is to provide a method for flash spinning a polyolefin, which can obtain a three-dimensional fiber having high strength and excellent openability by using this solvent.

[0027]

In order to achieve the above-mentioned object, the present inventors have conducted a great deal of research on solvent screening to find a fiber comparable to or superior to a polyolefin three-dimensional fiber by a conventional flash spinning method. Through trial and error, it was possible to reach the present invention as a result of trial and error on how to obtain a fiber having the following performance.

That is, according to the present invention, the polyolefin solution prepared at high temperature and high pressure is passed through a decompression orifice, a decompression chamber and a spinneret and discharged into a room temperature and pressure range to produce a fibrillated polyolefin three-dimensional fiber. In the method, the solvent is 1,2-dichloro-1,2-difluoroethylene, 1,1-dichloro-2,2-difluoroethylene,
1,2-dichloro-1-fluoroethylene, 1,1-dichloro-2-fluoroethylene is selected from the group consisting of, and the polyolefin concentration in the polyolefin solution is 5 to 2
A method for producing a polyolefin three-dimensional fiber, characterized in that the content is 5% by weight.

According to this method, the present inventors have developed a three-dimensional polyolefin having a markedly high strength and a good openability, which is different from the conventionally known improvement method, even though the solvent has a small ozone depleting ability. The fiber could be obtained. As described above, the solvent used for flash spinning is premised on being an organic solvent that becomes a gas at normal temperature and pressure. That is, the polyolefin is melted under high temperature and high pressure, then the pressure is once lowered to change the phase from a transparent liquid to an opaque liquid, and then the opaque polymer solution is blown out through a spinneret into an atmosphere at normal temperature and normal pressure. At this time,
The organic solvent gasifies to form a supersonic gas jet. The polymer is solidified and stretched by this gas jet, and becomes a three-dimensional fiber having high strength.

Therefore, the properties to be possessed as the flash spinning solvent have been disclosed as described above, but the details are as follows. At normal temperature and pressure, the polymer does not dissolve at all, but at temperatures above the melting point of the polymer and at high pressures far above atmospheric pressure, the polymer is dissolved. Phase change from a transparent liquid to an opaque liquid at a temperature above the melting point of the polymer and at which thermal degradation does not occur, especially in the case of flash spinning, LCS referred to as polymer solution theory
T (L ower C ritical S olution T emperature, lower critical solution temperature) is preferably in the polymer solution with type phase diagram, it is preferable that flash spinning solvent also has an LCST type phase diagram. Moreover, it is preferable to have an LCST type phase diagram, and moreover, the phase change should occur instantaneously. This property is important because flash spinning causes a phase change from transparent to opaque under pressure.

At the moment of leaving the spinneret, it must be gasified. This means that it must have a boiling point near normal temperature and normal pressure. That is, it must be a low boiling organic solvent. The change before and after the spinneret is almost isentropic change. Therefore, the spinneret outlet spontaneously becomes a liquid / gas mixture. As it is, it becomes a wet three-dimensional fiber and cannot be used. However, since the polymer has heat, this amount of heat gasifies the liquid to form a dry three-dimensional fiber. This means that the heat of vaporization of the organic solvent must be appropriate.

The organic solvent must have good thermal stability as it is exposed to temperatures above the melting point of the polymer. It must be non-combustible or flame-retardant because there is electrical equipment that fills a large-capacity enclosed space and is an ignition source in the enclosed space. The gas that fills the enclosed space is often touched by humans, so it must be non-toxic.

Since the flash spinning apparatus as a whole becomes a high-pressure apparatus, it must be a solvent having low corrosiveness. It must have a low ozone depletion capacity. Particularly important are low boiling point, LCST type polymer solution, thermal stability, low flammability, and low ozone depletion ability.

The inventors of the present invention have found out a flash spinning solvent satisfying the following five conditions: low boiling point, LCST type polymer solution, thermal stability, low flammability, and low ozone depleting ability.
Very many experiments were conducted. As a result, 1,2-dichloro-1,2-difluoroethylene, 1,1-dichloro-
It was found that the solvent of 2,2-difluoroethylene, 1,2-dichloro-1-fluoroethylene and 1,1-dichloro-2-fluoroethylene completely or almost completely satisfies the above-mentioned 5 conditions.

Hereinafter, the reason why the solvent and the solution used in the present invention satisfy the above-mentioned 5 conditions particularly required for flash spinning, the characteristics, the preferable composition range and the like will be described. Boiling point Boiling point is 50 ° C for gasification at normal temperature and pressure
The following are preferred. The boiling point of the solvent used in the present invention is 19 to
It is in the range of 37 ° C. Specifically, the boiling point of 1,2-dichloro-1,2-difluoroethylene is 21-22.
℃, 1,1-dichloro-2,2-difluoroethylene boiling point is 19 ℃, 1,2-dichloro-1-fluoroethylene boiling point is 35 ℃, 1,1-dichloro-2-fluoroethylene The boiling point is 37 ° C, and all the solvents have a very favorable boiling point for flash spinning. Furthermore,
Since all of these solvents have a freon structure, the heat of evaporation is small and the spun fiber does not get wet.

Cloud Point Curve The solvent used in the present invention becomes an LCST type polymer solution when polyolefin is dissolved therein. As described above, the basic principle of flash spinning is that the polymer solution at high temperature and high pressure is decompressed to be phase-separated into an opaque liquid composed of at least two phases of the polymer and the solvent, and then spun. Therefore, the cloud point temperature and pressure that can be determined by changing from a transparent liquid to an opaque liquid are extremely important.

This cloud point is also the point where phase separation occurs. The cloud point is indicated by the temperature and pressure at the point where the liquid changes from transparent to opaque. In polymer chemistry, a diagram in which this cloud point is plotted on temperature and pressure coordinates is called a cloud point curve. The suitability of the solvent for flash spinning can be judged from the position of the cloud point curve on the temperature / pressure coordinate plane. To show flash spinnability specifically, the cloud point pressure is about 100 to 400 k at around 200 ° C. when high density polyethylene is used.
It should be in the range of g / cm ³ . In the case of the solvent used in the present invention, any of the solvents exhibits the above preferable cloud point pressure. The optimization of the cloud point pressure can be performed on the delicate balance between the molecular weight of the solvent, the number of chlorine atoms, the number of fluorine atoms and the number of carbon atoms.

FIG. 1 shows an example of a cloud point curve. The cloud point curve in FIG. 1 shows the cloud point when 1,2-dichloro-1,2-difluoroethylene was used.
The upper region of each cloud point curve is a one-phase region, and the lower region is a two-phase region. The polymer has a density of 0.97 g / cm ³ ,
It is a high-density polyethylene having a weight average molecular weight of 102000 (dispersion degree of 6.14) and a polymer concentration of 18% by volume. Thermal stability The solvent used in the present invention has sufficient thermal stability to withstand use under the conditions of flash spinning. However, when it is exposed to high-temperature and high-pressure conditions for a long period of time, oligomerization may occur, so the residence time at high temperature and high pressure should be as short as possible. In particular, 1,1-dichloro-2,2-
It should be noted that difluoroethylene and 1,1-dichloro-2-fluoroethylene have slightly higher thermal decomposability than the other two solvents. Flammability All the solvents used in the present invention are substantially nonflammable,
Can be used without problems. Ozone-depleting ability OH determines the lifetime of halogen compounds in the atmosphere.
It is an active chemical species called a radical. It is produced by the reaction of oxygen and organic matter under the ultraviolet light from the sun.
Since the solvents used in the present invention each have a double bond, it is difficult to react with OH radicals and remain in the atmosphere, and the lifetime of the atmosphere is extremely short. Therefore, the solvent used in the present invention has substantially no ozone depleting ability.

Since the method of the present invention substantially uses a solvent having no ozone depleting ability, it can be used forever without any problem. To date, some flash-spinning solvents using alternative CFCs having a low ozone depletion ability have been disclosed, but these solvents have ozone depletion ability, albeit at low levels. .
With the ever-increasing regulations on chlorofluorocarbons, it is clear how important and excellent the present invention is to use a solvent that has no ozone depleting ability and is nonflammable.

The method for producing a three-dimensional fiber of the present invention using the flash-spinning solvent determined as described above spins excellent three-dimensional fiber having good openability and high strength without getting wet. Thus, a good nonwoven sheet can be obtained. In the method for producing a polyolefin three-dimensional fiber of the present invention, the weight ratio of the flash spinning solvent and the polyolefin is 5 to 25% by weight. Within this range, it is possible to easily produce a polyolefin three-dimensional fiber having excellent fiber-opening property and high strength. If it is 5% by weight or less, it becomes a pulp-like or low-strength fiber, and if it is 25% by weight or more, the fiber openability becomes low, which is not preferable in any case.
More preferably, it is 10 to 20% by weight.

As the polyolefin, polyethylene,
Examples include polypropylene and polymethylpentene-1. The polyethylene is most preferably high-density polyethylene, and the density is 0.94 g / cm ³ or more. Further, the copolymerization component is preferably 15% by weight or less and maintains the above-mentioned density. The polypropylene preferably contains about 85% by weight or more of isotactic polypropylene, and may contain about 15% by weight or less of other polypropylene or a copolymerization component such as ethylene or butene. Further, a polymer additive, a light stabilizer, a lubricant, a nucleating agent, a cross-linking agent, a plasticizer, a filler and the like which are generally known may be contained in the polymer.

The apparatus used in the present invention may be equipped with a dissolution adjusting apparatus, a decompression orifice, a decompression chamber, and a spinning device including a spinneret. Before that, there are a device for opening and dispersing the three-dimensional fibers, a moving conveyor device for forming the opened and dispersed three-dimensional fibers into a sheet, and a winder for winding the resulting sheet. The sheet forming unit is housed in a closed box, and the solvent gas in the box is collected. The solution adjusting device may be an autoclave device or an extruder. Alternatively, a conventionally known device can be used.

[0043]

The contents of the present invention will be described with reference to the following examples.

[0044]

Example 1 81.7 g of high-density polyethylene having a melt index of 0.78 and 481 g of 1,2-dichloro-1,2-difluoroethylene were charged into an autoclave,
(Polymer concentration 14.5% by weight) The autoclave was heated while rotating the propeller type stirrer to dissolve the high density polyethylene. The solution was further heated and the solution pressure was increased to completely dissolve the polymer. After dissolution, the solution was discharged from the discharge nozzle at the bottom of the autoclave so that the solution pressure does not exceed 300 kg / cm ² , and the pressure was adjusted to 200-
It was kept at 300 kg / cm ² .

When the temperature of the solution reached 200 ° C., the solution was discharged, and pressure was applied when spinning 250 kg / cm ^2.
10 kg / cm ² lower pressure than that, adjust the solution temperature to 200 ° C., open the nitrogen gas introduction valve at the top of the autoclave, pressurize nitrogen at 250 kg / cm ² , and quickly open the discharge valve at the bottom of the autoclave. It was Then, the solution was put into a vacuum orifice (diameter 0.65 mm,
Pass through a decompression chamber (diameter 8 mm, length 40)
mm), a spinneret (introduction angle from the decompression chamber to the nozzle 60 °, nozzle diameter 0.5 mm, length 0.5 mm, a circular groove of 3.3 mmφ and 3 mm depth outside the nozzle). Have) and released into the atmosphere. The open fiber is about 4 at about 20-40 mm away from the spinneret.
It was made by hitting a vinyl chloride plate inclined at 5 °. The opened fiber was received by a 10-mesh wire net and collected.

The obtained fiber has a fineness of 8 in an unopened state.
4d, tensile strength 6.3g / d, tensile elongation 4
2%, specific surface area 36 m ² / g, fineness 8 when opened
3d, tensile strength 6.1g / d, tensile elongation 4
It was a good three-dimensional fiber at 0%.

[0047]

Comparative Example 1 Fibers were produced by repeating the same conditions as in Example 1 except that trichlorofluoromethane was used as the solvent and the polymer concentration was 12.5% by weight. The obtained fiber has a fineness of 99d and a tensile strength of 5. in an unopened state.
4 g / d, tensile elongation 27%, specific surface area 21.2
It was m ² / g.

[0048]

Example 2 Spinning was carried out while fixing the polymer and solvent composition, the spinning device and the like under the same conditions as in Example 1 except that only the polymer concentration was changed. In an unopened state, when the polymer concentration is 7.5% by weight, the strength is 3.8 g / d, 2
At 0.3% by weight, the strength was 5.3 g / d.

[0049]

Example 3 Instead of 1,2-dichloro-1,2-difluoroethylene, 1,1-dichloro-2,2-difluoroethylene, 1,2-dichloro-1-fluoroethylene,
The same conditions as in Example 1 were repeated except that 1,1-dichloro-2-fluoroethylene was used to produce fibers. 1,
With 1-dichloro-2,2-difluoroethylene, the fineness is 75d and the tensile strength is 6.0g / d in the unopened state.
In the case of 1,2-dichloro-1-fluoroethylene having a tensile elongation of 38%, the fineness is 86d in an unopened state, the tensile strength is 5.8 g / d, the tensile elongation is 37%, 1,1-
With dichloro-2-fluoroethylene, the fineness was 78 d, the tensile strength was 5.7 g / d, and the tensile elongation was 41% in the unopened state.

[0050]

Industrial Applicability The production method of the present invention produces a socially useful three-dimensional fiber having the strength and openability equivalent to or higher than the case of using trichlorofluoromethane without destroying the ozone layer. It can be manufactured. The present invention is
Compared to the conventionally known flash spinning method that uses a solvent that can replace trichlorofluoromethane, it is significantly superior in openability,
In addition, it is possible to easily manufacture a three-dimensional fiber of polyolefin having high strength while always maintaining stable productivity. This industrial significance is of great value.

[Brief description of drawings]

FIG. 1 is a graph showing an example of a cloud point curve of a polymer solution of the present invention.

Claims (1)

[Claims] 1. A method for producing a fibrillated three-dimensional fiber of polyolefin by passing a polyolefin solution adjusted at high temperature and high pressure through a decompression orifice, a decompression chamber and a spinneret and releasing it into a room temperature and pressure region. 1,2-dichloro-1,2-difluoroethylene, 1,1-dichloro-2,2-difluoroethylene, 1,2-dichloro-1-
A method for producing a polyolefin three-dimensional fiber, which is selected from the group consisting of fluoroethylene and 1,1-dichloro-2-fluoroethylene, wherein the polyolefin solution has a polyolefin concentration of 5 to 25% by weight.