JPH06192954A - Extra fine fiber non-woven fabric and its production - Google Patents

Abstract

PURPOSE:To provide the extra fine fiber non-woven fabric excellent in mechanical characteristics, dimensional stability and flexibility by spinning a fiber-forming thermoplastic polymer by a melt-blown method, drawing and cooling the spun polymer into fine fibers with the flow of a high pressure gas, accumulating the fine fibers on a moving collecting surface, and subsequently three-dimensionally interlacing the collected fine fibers with a high pressure fluid. CONSTITUTION:A fiber-forming thermoplastic polymer such as polypropylene, polycaproamide or polyethylene terephthalate is spun by a melt-blown method. The spun polymer flow is drawn and divided into fine fibers through the flow of a high pressure gas having a temperature higher 20-50 deg.C than the melting point of the polymer, cooled and accumulated on a moving collecting surface as extra fine fibers having an average fiber diameter of 0.1-10mum to form a web. The web is treated with the column-like flows of high pressure water from the upper side of the web to interlace the fibers with each other into a three-dimensional structure. The interlaced product is subjected to the squeezing-out of excessive water with a mangle, and subsequently dried to provide the extra fine fiber non-woven fabric having a a tensile strength of <=20g/5cm per metsuke (unit weight) on the elongation of 10% and a compression bending resistance of <=0.5g per metsuke.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrafine fiber nonwoven fabric having excellent mechanical properties, dimensional stability and flexibility, which is suitable as a material for industrial materials and clothing, and a method for efficiently producing the same. is there.

[0002]

2. Description of the Related Art An ultrafine fiber nonwoven fabric manufactured by a melt blown method using a usual fiber-forming thermoplastic synthetic polymer has been conventionally known. The melt-blown method is a method in which a melt-spinning die discharges a molten polymer and at the same time draws and thins a polymer stream melt-spun by a high-temperature high-pressure air stream to obtain ultrafine fibers. For example, Industrial and Engineering Chemistry No. 48 No. 8, pp. 1342 to 1346 (1956) discloses a basic apparatus and method of the melt blown method. The melt blown method is applicable to obtain various raw materials because extremely fine fibers can be obtained. Has been done. However, although the ultrafine fiber non-woven fabric obtained by the melt blown method is widely used as various life-related materials and materials for industrial materials, it has a problem of poor mechanical properties. On the other hand, the mechanical properties of the non-woven fabric are improved by subjecting the ultra-fine fiber non-woven fabric produced by the melt blown method using the ordinary fiber-forming thermoplastic synthetic polymer to the partial thermocompression bonding between the constituent fibers using the hot embossing roller. It is known that this can be done. However, although the non-woven fabric obtained by partially thermocompressing the constituent fibers using this hot embossing roller has improved mechanical properties,
There was a problem that flexibility was impaired.

[0003]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems and is excellent in mechanical properties, dimensional stability and flexibility, and is an ultrafine fiber nonwoven fabric suitable as a material for industrial materials and clothing, and
It is intended to provide a method capable of efficiently manufacturing the same.

[0004]

The present inventors have arrived at the present invention as a result of intensive studies to solve the above problems. That is, the present invention comprises ultrafine fibers having a fiber-forming thermoplastic synthetic polymer and an average fiber diameter of 0.1 to 10.0 μm. A gist of an ultrafine fiber non-woven fabric having a tensile stress of 20 g / 5 cm or less per unit weight and a compression rigidity of 0.5 g or less per unit weight. Further, in the present invention, in producing an ultrafine fiber nonwoven fabric by the melt blown method, a fiber-forming thermoplastic synthetic polymer is melt-spun, and the melt-spun polymer stream is melted at a temperature not lower than 20 ° C.
〜50 ℃ Draw and web by high pressure air flow at high temperature, cool and cool, then collect and deposit on moving moving collecting surface to make web, and then apply high pressure liquid flow treatment to the obtained web The gist is a method for producing an ultrafine fiber nonwoven fabric, which is characterized by intertwining three-dimensionally with each other.

Next, the present invention will be described in detail. The fiber-forming thermoplastic synthetic polymer in the present invention is a polyolefin polymer, a polyamide polymer or a polyester polymer having a so-called fiber forming property. Examples of the polyolefin polymer include aliphatic α-monoolefins having 2 to 18 carbon atoms, such as ethylene, propylene,
A homopolyolefin polymer composed of butene-1, pentene-1,3-methylbutene-1, hexene-1, octene-1, dodecene-1, octadecene-1 can be mentioned. This aliphatic α-monoolefin is a polyolefin in which other ethylenically unsaturated monomers are copolymerized with similar ethylenically unsaturated monomers such as butadiene, isoprene, pentadiene-1.3, styrene, and α-methylstyrene. It may be a system copolymer. In the case of a polyethylene-based polymer, ethylene is propylene,
Butene-1, hexene-1, octene-1, or a similar higher α-olefin may be copolymerized in an amount of 10% by weight or less. In the case of a polypropylene-based polymer, it may be ethylene or similar to propylene. The higher α-olefin may be copolymerized in an amount of 10% by weight or less, but when the copolymerization rate of these copolymers exceeds the above% by weight, the melting point of the copolymer decreases, When a nonwoven fabric obtained by using the copolymer is used under high temperature conditions, mechanical properties and dimensional stability are deteriorated, which is not preferable.

Polyamide polymers include polyimino-1-oxotetramethylene (nylon 4), polytetramethylene adipamide (nylon 46), polycapramide (nylon 6), polyhexamethylene adipamide (nylon 66), Polyundecanamid (nylon 11),
Examples thereof include polylaurolactamide (nylon 12), polymethaxylene adipamide, polyparaxylylene decanamide, polybiscyclohexylmethane decanamide, or a polyamide-based copolymer having these monomers as a constituent unit. Particularly, in the case of polytetramethylene adipamide, polytetramethylene adipamide is a polycapramide, polyhexamethylene adipamide, polyundecamethylene terephthalamide, or other polyamidopolyamide copolymerized by 30 mol% or less. It may be a tetramethylene adipamide-based copolymer. When the copolymerization rate of the other polyamide component exceeds 30 mol%, the melting point of the copolymer is lowered, and mechanical properties and dimensional stability are lowered when the nonwoven fabric is used under high temperature conditions, which is not preferable.

As the polyester polymer, an aromatic dicarboxylic acid such as terephthalic acid, isophthalic acid, naphthalene-2,6-dicarboxylic acid, or an aliphatic dicarboxylic acid such as adipic acid or sebacic acid, or an ester thereof is used as an acid component. And a homopolyester polymer or copolymer containing a diol compound such as ethylene glycol, diethylene glycol, 1,4-butadiol, neopentyl glycol, cyclohexane-1,4-dimethanol as an ester component. In addition, these polyester-based polymers include paraoxybenzoic acid, 5-sodium sulfoisophthalic acid, polyalkylene glycol,
Pentaeryththritol, bisphenol A, etc. may be added or copolymerized.

In the present invention, the above-mentioned thermoplastic polymer may be blended with the fiber-forming thermoplastic polymer within a range not impairing the spinnability. For example, two different polyamide polymers may be blended and used, or a polyester polymer and a polyolefin polymer may be blended and used. In particular,
In the latter case, the shrinkage of the unoriented and low crystalline polyester component immediately after melt spinning can be suppressed, which is preferable. In the present invention, the fiber-forming thermoplastic polymer may contain, for example, a matting agent, a pigment, a flameproofing agent, a deodorant, a light stabilizer, a heat stabilizer, an antioxidant, etc., if necessary. Various additives can be added within a range that does not impair the effects of the present invention.

The ultrafine fibers made of the polyolefin polymer in the present invention have an average fiber diameter of 0.1 to 10.0.
If the average fiber diameter is less than 0.1 μm, the spinnability is deteriorated. On the other hand, if the average fiber diameter exceeds 10.0 μm, the obtained web has a hard texture and is highly flexible. Cannot be obtained, and neither is preferable.

The nonwoven fabric composed of the ultrafine fibers in the present invention is one in which the constituent fibers are three-dimensionally entangled with each other, and the tensile stress at 10% elongation is 20 g / 5 cm or less per unit weight. This three-dimensional entanglement is formed by a known so-called high-pressure liquid flow treatment, whereby the shape of the nonwoven fabric is maintained. In this non-woven fabric, the fused portion that is inevitably generated between spun fibers in the melt-blown spinning process is destroyed by the action of the high-pressure liquid flow, and a sufficient three-dimensional entanglement is formed between the fibers. Has sufficient mechanical properties and dimensional stability even in the absence of And, since this non-woven fabric is composed of ultrafine fibers obtained by the melt blown method and has a structure in which the ultrafine fibers are three-dimensionally entangled by the high pressure liquid flow treatment,
The tensile stress at 10% elongation is 20 g / 5 cm or less per unit weight, and the compression stiffness per unit weight is 0.5 g or less, which is extremely flexible.

The non-woven fabric made of the ultrafine fibers in the present invention can be efficiently produced by a known so-called melt blown method. That is, a polyolefin polymer is melt-spun by a melt blown method, and the melt-spun polymer stream is drawn / thinned by a high-pressure air stream at a temperature 20 to 50 ° C higher than the melting temperature, cooled, and then moved to a collecting surface. The web is obtained by collecting and depositing it on the top, and then the obtained web is subjected to a high-pressure liquid flow treatment to entangle the constituent fibers three-dimensionally. In the production method of the present invention, a fiber-forming thermoplastic synthetic polymer that can be melt-spun as described above and has fiber-forming properties is used.
During melt-spinning by the melt blown method, the high-pressure air stream that pulls and thins the melt-spun polymer stream has a temperature 20 to 50 ° C. higher than the melting temperature of the polymer stream. If the temperature is less than + 20 ° C from the melting temperature, it becomes difficult to form ultrafine fibers when the fiber structure is formed, and on the other hand, this temperature is higher than the melting temperature of the polymer flow.
If the temperature exceeds 50 ° C., the mechanical properties of the obtained nonwoven fabric are deteriorated, and in an extreme case, the spun fiber is blown off by the high-pressure air flow to become a short fiber, which is not preferable.

In performing the high pressure liquid flow treatment, a known method can be adopted. For example, if the pore size is 0.05
~ 1.0mm, especially 0.1 ~ 0.4mm using a device with a large number of injection holes arranged, the injection pressure 5 ~ 150kg / cm ²
There is a method of ejecting the G high-pressure liquid from the ejection hole. The injection holes are arranged in rows in a direction orthogonal to the direction of travel of the web. This treatment may be performed on one side or both sides of the web. In particular, in the case of one-side treatment, the injection holes are arranged in a plurality of rows and the injection pressure is lowered in the front stage and increased in the rear stage. As a result, it is possible to obtain a non-woven fabric having a uniform and dense entangled form and a uniform texture. Generally, water or hot water is used as the high-pressure liquid. The distance between the injection hole and the web is preferably 1 to 15 cm. When this distance is less than 1 cm, the texture of the web is disturbed, while when this distance exceeds 15 cm, the impact force when the liquid flow collides with the web is reduced and the three-dimensional entanglement is not sufficiently performed. Is also not preferable. This high pressure liquid flow treatment may be either a continuous process or a separate process. By this high-pressure liquid flow treatment, the constituent fibers of the non-woven fabric are entangled three-dimensionally, and the degree of entanglement can be adjusted depending on various conditions such as the structure of the injection holes in the high-pressure liquid flow treatment, and the pressure and flow rate of the liquid flow. However, in addition to these conditions, it is also possible under the conditions of the web forming process. That is,
In the melt blown method, the polymer stream melt-spun from the spinneret is drawn and thinned by a high-pressure air stream, cooled, and then collected and deposited on a moving collecting surface to form a web, which is then collected with the spinneret. The degree of entanglement changes in proportion to the distance from the surface. For example, as this distance is increased, the degree of freedom of the fibers that make up the web increases, and the effect of high-pressure liquid flow treatment becomes more likely to be exhibited. Therefore, the degree of confounding can be adjusted by adjusting this distance. The non-woven fabric obtained by this high-pressure liquid flow treatment is composed of ultrafine fibers obtained by the melt blown method and has a structure in which the ultrafine fibers are three-dimensionally entangled by the high-pressure liquid flow treatment. Tensile stress is 20 per unit weight
g / 5 cm or less, and the compression stiffness per unit weight is 0.
It has extremely excellent flexibility of 5 g or less. When performing the high-pressure liquid flow treatment, the structure or handle of the non-woven fabric can be changed by appropriately changing the mesh or woven structure of the screen carrying the web.

After the high-pressure liquid flow treatment, excess moisture is removed from the web, which is then dried and heat-treated to obtain a final product. A known method can be adopted for removing the excess water, and the excess water is removed to some extent by using a squeezing device such as a mangle roll. Further, a known method can be adopted for the drying, and the residual water content is removed by using a drying device such as a continuous hot air dryer. Furthermore, when performing the heat treatment, besides the dry heat treatment using a drying device such as a continuous hot air dryer, a wet heat treatment may be performed if necessary. When selecting the conditions such as temperature and time in the drying / heat treatment, it is possible to select not only simple water removal but also allow an appropriate shrinkage of the nonwoven fabric as required.

[0014]

EXAMPLES Next, the present invention will be specifically described based on examples, but the present invention is not limited to these examples. In the examples, each characteristic value was measured by the following method. Melting point (℃): Differential scanning calorimeter DS manufactured by Perkin Elma
Using a C-2 type, the measurement is performed at a temperature rising rate of 20 ° C./min,
The temperature that gives the extreme value in the obtained melting endothermic curve was taken as the melting point. Melt flow rate value (g / 10 minutes): ASTM D1
It was measured according to the method described in 238 (L). Relative viscosity 1: The relative viscosity of the polycapramide polymer (nylon 6 polymer) was determined by dissolving 1 g of the sample in 100 cc of 96% sulfuric acid and measuring the temperature at 25 ° C. by a conventional method. Relative viscosity 2: The relative viscosity of the polyethylene terephthalate polymer was measured by an ordinary method at a temperature of 20 ° C. using a solvent of equal weight solution of phenol and ethane tetrachloride as a solvent and dissolving 0.5 g of a sample. I asked. Average fiber diameter (μm): Obtained by taking an electron micrograph of the sample. Tensile strength (kg) and tensile elongation (%): JIS-L-1
It was measured according to the method described in 096A. That is, 10 sample pieces having a sample length of 10 cm and a sample width of 5 cm were prepared, and a constant speed extension type tensile tester (Tensilon UTM-made by Toyo Baldwin Co., Ltd.
4-1-100) and stretching at a tensile speed of 10 cm / min, the obtained tensile load (kg) is the tensile strength (kg), and the average tensile elongation (%) is the tensile elongation. The degree (%). Compression stiffness per unit weight (g): JIS-L-1096
It was measured according to the strip method described in. That is, five sample pieces having a sample length of 10 cm and a sample width of 5 cm were prepared, and each sample piece was bent laterally to form a cylindrical body,
The end portions are joined to form a sample for measuring compression stiffness, and a constant speed extension type tensile tester (Tensilon UTM-4-1-10, manufactured by Toyo Baldwin Co., Ltd.) is used for each measurement sample in the longitudinal direction.
0) was used for compression at a compression rate of 5 cm / min, and the maximum load (g) obtained was divided by the unit weight (g / m ² ) of the sample piece to obtain the average value of the compression stiffness per unit weight (g). And

Example 1 Melting point: 160 ° C. Melt flow rate: 400 g / 1
A non-woven fabric was produced by a melt blown method using a 0-minute polypropylene polymer chip. That is, the polymer chip is melted, and is melted from the spinneret at a spinning temperature of 280
The polymer flow spun at a single-hole discharge rate of 0.2 g / min at ℃ was drawn and thinned by a high-pressure air flow. As the high-pressure air stream, heated air having a temperature of 320 ° C. and a pressure of 1.4 kg / cm ² was used. Following drawing and thinning, the polymer stream was cooled and formed into fibers, which were then collected and deposited on a wire mesh belt which was placed 20 cm away from the spinneret and moved at a speed of 6.7 m / min. The web. Next, the obtained web was placed on a wire mesh of 100 mesh, water was applied to the web using a water applicator, and then high pressure liquid flow treatment was performed to entangle the constituent fibers three-dimensionally. As the high-pressure liquid flow treatment, a high-pressure columnar water flow treatment device in which injection holes having a hole diameter of 0.12 mm were arranged in a three-group arrangement with a hole interval of 0.6 mm was used, and a position 8 cm above the web was placed under a water pressure of 30 kg / cm ^2. A columnar water stream was made to act. This treatment was performed three times from the front and back of the web. Next, after removing excess water from the obtained treated web by using a mangle roll, the web was dried at a temperature of 98 ° C. using a hot air dryer to obtain a nonwoven fabric. The characteristics of the obtained non-woven fabric are shown in Table 1. As is clear from Table 1, the nonwoven fabric of the present invention had excellent mechanical properties and flexibility.

Example 2 The non-woven web obtained in Example 1 before being subjected to the high-pressure liquid flow treatment was placed on a wire mesh of 36 mesh, water was applied thereto by using a water applicator, and then water pressure was applied. A non-woven fabric was obtained in the same manner as in Example 1 except that 40 kg / cm ² was used. The characteristics of the obtained non-woven fabric are shown in Table 1. As is clear from Table 1, the non-woven fabric of the present invention had excellent mechanical properties and flexibility, and also had an open pattern.

Example 3 A non-woven fabric was produced by a melt blown method using a polycapramide polymer (nylon 6 polymer) chip having a melting point of 214 ° C. and a relative viscosity of 2.4. That is, the polymer chip is melted and the spinning temperature is set to 320 from the spinneret.
The polymer flow spun at a single-hole discharge rate of 0.2 g / min at ℃ was drawn and thinned by a high-pressure air flow. As the high-pressure air stream, heated air having a temperature of 350 ° C. and a pressure of 1.6 kg / cm ² was used. Following drawing and thinning, the polymer stream was cooled and formed into fibers, which were then collected and deposited on a wire mesh belt which was placed 25 cm away from the spinneret and moved at a speed of 6.7 m / min. The web. Next, the obtained web was placed on a wire mesh of 100 mesh, water was applied to the web using a water applicator, and then high pressure liquid flow treatment was performed to entangle the constituent fibers three-dimensionally. As the high-pressure liquid flow treatment, a high-pressure columnar water flow treatment device in which injection holes with a hole diameter of 0.12 mm were arranged in a three-group arrangement with a hole interval of 0.6 mm was used, and the position 8 cm above the web was set under a water pressure of 40 kg / cm ^2. A columnar water stream was made to act. This treatment was performed three times from the front and back of the web. Next, after removing excess water from the obtained treated web by using a mangle roll, the web was dried at a temperature of 98 ° C. using a hot air dryer to obtain a nonwoven fabric. The characteristics of the obtained non-woven fabric are shown in Table 1. As is clear from Table 1, the nonwoven fabric of the present invention had excellent mechanical properties and flexibility.

Example 4 A non-woven fabric was produced by a melt blown method using a polyethylene terephthalate polymer chip having a melting point of 260 ° C. and a relative viscosity of 1.24. That is, the polymer chip was melted, spun from the spinneret at a spinning temperature of 350 ° C., single hole discharge rate of 0.2 g / min, and the melt spun polymer stream was drawn and thinned by a high-pressure air stream. . As the high-pressure air stream, heated air having a temperature of 380 ° C. and a pressure of 1.2 kg / cm ² was used. Following drawing and thinning, the polymer stream was cooled to form fibers, which were then collected and deposited on a wire mesh belt which was placed 15 cm away from the spinneret and moved at a speed of 6.7 m / min. The web. Next, the obtained web was placed on a wire mesh of 100 mesh, water was applied to the web using a water applicator, and then high pressure liquid flow treatment was performed to entangle the constituent fibers three-dimensionally. As a high-pressure liquid flow treatment, injection holes with a hole diameter of 0.12 mm have a hole spacing of 0.6 mm.
Using a high-pressure columnar water stream treatment device arranged in three groups
A columnar water stream was applied from a position 8 cm above the web under a water pressure of 40 kg / cm ² . This treatment was performed three times from the front and back of the web. Next, after removing excess water from the obtained treated web by using a mangle roll, the web was dried at a temperature of 98 ° C. using a hot air dryer to obtain a nonwoven fabric. The characteristics of the obtained non-woven fabric are shown in Table 1. As is clear from Table 1, the nonwoven fabric of the present invention had excellent mechanical properties and flexibility.

Comparative Example 1 Melt flow rate value was 60 g / 10 minutes, spinning temperature was 3
The polymer stream melt-spun at 20 ° C. was drawn and thinned by a heated high-pressure air stream at a temperature of 360 ° C. and a pressure of 2.1 kg / cm ² , from a position 30 cm above the web under the condition of a water pressure of 60 kg / cm ^2. A non-woven fabric was obtained in the same manner as in Example 1 except that a columnar water flow was applied. In drawing and thinning the melt-spun polymer stream by the heated high-pressure air stream,
Since the polymerization degree of the polymer is too high, polymer balls are frequently generated on the surface of the melt-spinning spinneret during the yarn making process, and the spinnability is deteriorated. Was difficult to form. Table 1 shows the characteristics of the obtained non-woven fabric. The resulting non-woven fabric is
As is clear from Table 1, the intertwining of the constituent fibers was insufficient, resulting in poor mechanical properties and poor flexibility, making it difficult to put into practical use.

Comparative Example 1 The nonwoven web obtained in Example 1 before the high pressure liquid stream treatment was evaluated. The properties of the resulting nonwoven web are shown in Table 1. This non-woven web has mechanical properties as shown in Table 1,
It was inferior in flexibility.

Comparative Example 2 The non-woven web obtained in Example 1 before being subjected to the high-pressure liquid flow treatment was subjected to a partial thermocompression treatment using a hot embossing roller having a temperature of 110 ° C. and a pressure contact area ratio of 14.2%. gave. The characteristics of the obtained non-woven fabric are shown in Table 1. As is clear from Table 1, the obtained nonwoven fabric had excellent mechanical properties but poor flexibility.

[0022]

[Table 1]

[0023]

The ultrafine fiber nonwoven fabric of the present invention has an average fiber diameter of 0.1 to 1 composed of a fiber-forming thermoplastic synthetic polymer.
It is composed of ultrafine fibers of 0.0μm, the constituent fibers are entangled three-dimensionally, the tensile stress at 10% elongation is 20g / 5cm or less per unit weight, and the compression stiffness per unit weight is 0.5g or less. It has excellent mechanical properties, dimensional stability and flexibility, and is suitable as a material for industrial materials and clothing. Further, according to the method for producing an ultrafine fiber nonwoven fabric of the present invention, the nonwoven fabric can be efficiently produced.

Claims (2)

[Claims] 1. A microfiber composed of a fiber-forming thermoplastic synthetic polymer and having an average fiber diameter of 0.1 to 10.0 μm, wherein the constituent fibers are three-dimensionally entangled with each other and stretched at 10% elongation. A microfiber nonwoven fabric having a stress of 20 g / 5 cm or less per unit weight and a compression stiffness of 0.5 g or less per unit weight. 2. When producing an ultrafine fiber non-woven fabric by the melt blown method, a fiber-forming thermoplastic synthetic polymer is melt-spun, and the melt-spun polymer stream is melted at a temperature not lower than 20.
〜50 ℃ Draw and web by high pressure air flow at high temperature, cool and cool, then collect and deposit on moving moving collecting surface to make web, and then apply high pressure liquid flow treatment to the obtained web A method for producing an ultrafine fiber non-woven fabric, which comprises entangled three-dimensionally with each other.