JPH0673654A - Polyamide ultrafine fiber non-woven fabric and its production - Google Patents

Abstract

PURPOSE:To provide the non-woven fabric excellent in mechanical characteristics, heat resistance, dimensional stability and flexibility, and suitable not only as a raw material for conventional clothes but also especially as a raw material for industrial materials. CONSTITUTION:This polyamide ultrafine non-woven fabric is composed of ultrafine fibers comprising a polytetramethylene adipamide polymer having a relative viscosity of 2.6-4.0 and having an average fiber diameter of 0.1-8.0mum, and has a dry heat shrinkage degree of <=20% at a temperature of 160 deg.C, the composed fibers being three-dimensionally interlaced with each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to mechanical properties, heat resistance,
The present invention relates to a polyamide-based ultrafine fiber nonwoven fabric which has excellent dimensional stability and flexibility and is particularly suitable as a material for industrial materials, and a method for efficiently producing the same.

[0002]

2. Description of the Related Art Conventionally, polyamide-based ultrafine fiber non-woven fabric manufactured by melt blown method using polycapramide or polyhexamethylene adipamide polymer has been known, and this non-woven fabric has toughness, abrasion resistance, alkali resistance, etc. Since it is excellent, it is widely used as a material for various industrial materials. By the way, in recent years, in industrial material applications, there has been a demand for a material having a property of withstanding a severely thermally and / or mechanically used condition. However, the polyamide-based ultrafine fiber non-woven fabric has a toughness,
Although it had excellent wear resistance and alkali resistance, it was insufficient in terms of heat resistance and dimensional stability.

[0003]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems, and has excellent mechanical properties, heat resistance, dimensional stability, and flexibility, and a polyamide-based ultrafine fiber nonwoven fabric particularly suitable as a material for industrial materials, 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 extensive studies to solve the above problems. That is, the present invention comprises ultrafine fibers having an average fiber diameter of 0.1 to 8.0 μm and made of a polytetramethylene adipamide polymer having a relative viscosity of 2.6 to 4.0 and a temperature of 16
It is a gist of a polyamide-based ultrafine fiber non-woven fabric, which has a dry heat shrinkage ratio of 20% or less at 0 ° C. and constituent fibers are three-dimensionally entangled. Further, in the present invention, when a polyamide-based ultrafine fiber nonwoven fabric is produced by the melt blown method, a polytetramethyleneadipamide-based polymer having a relative viscosity of 2.6 to 4.0 is used as a polymer and melt-spun. Polymer flow from melting temperature to 2
The high-pressure air flow of 0 to 50 ℃ higher temperature pulls and thins it,
After cooling, it is collected and deposited on a moving collecting surface to form a web, and then the obtained web is subjected to a high-pressure liquid flow treatment so that the constituent fibers are entangled three-dimensionally with each other. The gist of the present invention is a method for manufacturing an ultrafine fiber nonwoven fabric.

Next, the present invention will be described in detail. The polytetramethylene adipamide-based polymer in the present invention is a polymer mainly composed of polytetramethylene adipamide. Polytetramethylene adipamide is added to polycapramide, polyhexamethylene adipamide, polyundecamethylene terephthalate. 30 mol% of other polyamide components such as phthalamide
The polytetramethylene adipamide-based copolymer copolymerized below or a blended product may be used. If the copolymerization rate or the blending rate of the other polyamide component exceeds 30 mol%, the melting point of the copolymer or the blend lowers, and the mechanical properties and dimensional stability of the nonwoven fabric when used under high temperature conditions are reduced. It is not preferable because it decreases. The polytetramethylene adipamide-based polymer of the present invention has a relative viscosity of 2.6 to 4.0, and if the relative viscosity is less than 2.6, the strength of the nonwoven fabric is significantly reduced. If the relative viscosity exceeds 4.0, the degree of polymerization is too high, so that the spinnability deteriorates and it becomes difficult to form ultrafine fibers, and the energy required for fiber formation becomes large. In the present invention, the polytetramethylene adipamide-based polymer may be added with various additives such as a matting agent, a pigment, a light stabilizer, a heat stabilizer, and an antioxidant, if necessary. It can be added within a range that does not impair the effect.

The ultrafine fibers made of the polytetramethylene adipamide polymer in the present invention have an average fiber diameter of 0.1 to 8.0 μm and an average fiber diameter of 0.1.
If it is less than μm, the spinnability is deteriorated, while if the average fiber diameter exceeds 8.0 μm, the texture of the obtained web becomes hard and a flexible nonwoven fabric cannot be obtained, which is not preferable.

The nonwoven fabric composed of the ultrafine fibers in the present invention has a dry heat shrinkage of 20% or less at a temperature of 160 ° C. Fibers made of polytetramethylene adipamide-based polymer tend to increase in shrinkage as the fiber orientation increases, similar to fibers made of polycapramide or polyhexamethylene adipamide polymer. The degree of increase is not as high as that of polyhexamethylene adipamide. That is, when the polytetramethylene adipamide polymer is copolymerized or blended with another polyamide component in an amount of more than 30 mol%, the shrinkage rate greatly increases as the fiber orientation increases, and the resulting non-woven fabric is used. Will be extremely limited. On the other hand, since the nonwoven fabric of the present invention is composed of the fibers made of the above-mentioned specific polytetramethylene adipamide polymer, the shrinkage rate is suppressed, and the dry heat shrinkage rate at a temperature of 160 ° C. is 20% or less. And has excellent dimensional stability, and since it is composed of fibers made of the polytetramethylene adipamide polymer, it has a heat resistance higher than that of fibers made of conventional polycapramide or polyhexamethylene adipamide polymer. Excellent, therefore, it can be widely applied as a material for industrial materials.

The nonwoven fabric made of the ultrafine fibers in the present invention is one in which constituent fibers are three-dimensionally entangled. 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.

The non-woven fabric composed of the ultrafine fibers in the present invention can be efficiently produced by a known so-called melt blown method. That is, the relative viscosity is 2.6 to
Melt-spun by melt-blown method using 4.0 polytetramethylene adipamide-based polymer, and melt-spun polymer stream is drawn / thinned by high-pressure air stream at 20-50 ° C higher than melting temperature and cooled. After that, it is collected and deposited on the moving collecting surface to form a web, and then the obtained web is subjected to a high-pressure liquid flow treatment to entangle the constituent fibers three-dimensionally. During melt spinning by the melt blown method, the temperature of the high-pressure air stream that pulls and thins the melt-spun polymer stream is 20 to 50 ° C higher than the melting temperature of the polymer stream.
Higher temperature, which is +2 above the melting temperature of polymer flow
If the temperature is lower than 0 ° C, the spinnability is deteriorated and it becomes difficult to form ultrafine fibers. On the other hand, this temperature is +
If it exceeds 50 ° C., the discharge holes of the spinneret become dirty due to the decomposition of the polymer and the operability is deteriorated, which is not preferable. A well-known method can be adopted when performing the high-pressure liquid flow treatment. For example, if the pore size is 0.05-1.0
mm, particularly a device in which a large number of injection holes of 0.1 to 0.4 mm are arranged, there is a method of injecting a high pressure liquid having an injection pressure of 5 to 150 kg / cm ² G from the injection holes. 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. As a high pressure liquid,
It is common to use water or warm water. 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
It may be either a continuous process or a separate process. When performing the high-pressure liquid flow treatment, the structure or handle of the nonwoven fabric can be changed by appropriately changing the mesh or woven structure of the screen carrying the web.

After performing the high pressure liquid flow treatment, excess moisture is removed from the web. A known method can be adopted for removing the excess water. For example, a squeezing device such as a mangle roll is used to remove excess water to some extent, and then a drying device such as a continuous hot air dryer is used to remove the remaining water.

[0011]

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. Relative viscosity: Dissolve 1g of sample in 100cc of 96% sulfuric acid,
It was measured by a conventional method under the condition of a temperature of 25 ° C. 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 elongation type tensile tester (Tensilon UTM manufactured by Toyo Baldwin Co., Ltd.) was used for each sample piece in the warp direction of the nonwoven fabric.
-4-1-100) was used to stretch at a tensile speed of 10 cm / min, and the average value of the load values (kg) at break obtained was the tensile strength (kg) and the average value of the elongation at break (%). The tensile elongation (%) was used. Dry heat shrinkage (%): A plurality of sample pieces each having a sample length and a sample width of 25 cm were prepared, and each sample piece was heat-treated using a hot air dryer at a temperature of 160 ° C. for a treatment time of 5 minutes. . At this time, the area S1 of the sample piece before heat treatment and the area S2 of the sample piece after heat treatment were obtained, and the average value of the values calculated by the following equation (1) from the obtained S1 and S2 was taken as the dry heat shrinkage rate (%). . Dry heat shrinkage (%) = [1- (S2 / S1)] × 100 ... (1) Flexibility: 1 cm slit width according to the handle odometer method described in JIS-L-1096. It was measured under the conditions.

Example 1 A non-woven fabric was produced by a melt blown method using a polytetramethylene adipamide polymer chip having a melting point of 295 ° C. and a relative viscosity of 2.90. That is, the polymer chip was melted, spun from a die at a spinning temperature of 340 ° C. and a 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 this high-pressure air stream, heated air having a temperature of 370 ° C. and a pressure of 2.9 kg / cm ² was used. Following drawing and thinning, the polymer stream was cooled and formed into fibers, which were then collected on a wire mesh belt placed 50 cm away from the die and moving at a speed of 6.7 m / min.
It was deposited into a web. Then, the obtained web is 7
It was placed on a wire mesh of 8 mesh and subjected to high-pressure liquid flow treatment 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. Water pressure of 80 kg / cm ² A columnar water stream was applied from the position. 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 non-woven fabric of the present invention was excellent in mechanical properties, dimensional stability, flexibility and heat resistance.

Example 2 5% by weight of polycapramide was copolymerized with polytetramethylene adipamide. The melting point was 287 ° C. and the relative viscosity was 2.80.
Of the polytetramethylene adipamide-based copolymer is melted and spun from a die at a spinning temperature of 330 ° C. with a single hole discharge rate of 0.2 g / min. The melt spun polymer stream is heated at a temperature of 360 ° C. A wire mesh that is placed 60 cm away from the die and moves at a speed of 6.7 m / min after it has been drawn and thinned by a heated high-pressure air flow with a pressure of 2.8 kg / cm ² to cool the polymer flow to form fibers. A web was obtained by collecting and accumulating on a belt made of a belt, and then the obtained web was placed on a wire net and subjected to a high-pressure liquid flow treatment to entangle the constituent fibers three-dimensionally. As the high-pressure liquid stream treatment, the same high-pressure columnar water stream treatment apparatus as that used in Example 1 was used, and the columnar water stream was made to act under the same conditions. This treatment was performed three times from the front and back of the web. Then, after removing excess water from the obtained treated web using mangle rolls, Example 1
A nonwoven fabric was obtained in the same manner as in. 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 was excellent in mechanical properties, dimensional stability, flexibility and heat resistance.

Example 3 Relative viscosity 3.30, spinning temperature 345 ° C., melt spun polymer stream at temperature 380 ° C., pressure 3.0 kg / cm ^2.
Example 2 except that it was pulled / thinned by the heated high-pressure air stream of
A nonwoven fabric was obtained in the same manner as in. 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 was excellent in mechanical properties, dimensional stability, flexibility and heat resistance.

Comparative Example 1 Relative viscosity 4.20, spinning temperature 370 ° C., melt spun polymer stream at temperature 400 ° C., pressure 3.4 kg / cm ^2.
Example 2 except that it was pulled / thinned by the heated high-pressure air stream of
A nonwoven fabric was obtained in the same manner as in. When the melt-spun polymer stream was pulled and thinned by the heated high-pressure air stream, it was difficult to form ultrafine fibers even if the temperature and pressure of the heated air were increased because the relative viscosity was too high. Table 1 shows the characteristics of the obtained non-woven fabric. As is clear from Table 1, the obtained non-woven fabric was inferior in both mechanical properties and flexibility, and was yellowing due to the high spinning temperature, making it difficult to put into practical use.

Comparative Example 2 A non-woven fabric was produced by a melt blown method using a polycapramide polymer chip having a melting point of 210 ° C. and a relative viscosity of 2.80. That is, the polymer chip was melted, spun from a die at a spinning temperature of 270 ° C. and a 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. This high pressure air flow has a temperature of 310 ° C,
Heated air having a pressure of 2.7 kg / cm ² was used. Following drawing and thinning, the polymer stream was cooled and formed into fibers, which were then placed 70 cm away from the die and at a speed of 6.7 m.
A web was made by collecting and depositing it on a wire mesh belt moving at a speed of 1 / min. Then, the obtained web was placed on the wire mesh and subjected to high-pressure liquid flow treatment to entangle the constituent fibers three-dimensionally. . As the high-pressure liquid stream treatment, the same high-pressure columnar water stream treatment apparatus as that used in Example 1 was used, and the columnar water stream was made to act under the same conditions. Then, after removing excess water from the obtained treated web by using mangle rolls, a nonwoven fabric was obtained in the same manner as in Example 1. The characteristics of the obtained non-woven fabric are shown in Table 1. As is clear from Table 1, the obtained non-woven fabric was comparable to the non-woven fabric obtained in Example 1 in both mechanical properties and flexibility, but was inferior in dimensional stability and under high temperature conditions. It was not suitable for use.

[0017]

[Table 1]

[0018]

INDUSTRIAL APPLICABILITY The polyamide ultrafine fiber nonwoven fabric of the present invention has an average fiber diameter of 0.1 to 8.0 made of a polytetramethylene adipamide polymer having a relative viscosity of 2.6 to 4.0.
It consists of ultrafine fibers of μm, the dry heat shrinkage at temperature of 160 ℃ is 20% or less, and the constituent fibers are three-dimensionally entangled. Mechanical properties, heat resistance, and size. It has excellent stability and flexibility, and is suitable not only as a conventional material for clothing but also as a material for industrial materials. Further, according to the method for producing a polyamide-based ultrafine fiber nonwoven fabric of the present invention,
The nonwoven fabric can be efficiently manufactured.

Claims (2)

[Claims] 1. An average fiber diameter of a polytetramethylene adipamide polymer having a relative viscosity of 2.6 to 4.0 and an average fiber diameter of 0.1.
Consists of 1-8.0 μm ultrafine fibers, temperature 160 ℃
A polyamide-based ultrafine fiber non-woven fabric, which has a dry heat shrinkage of 20% or less and has three-dimensionally entangled constituent fibers. 2. A melt-spun polymer produced by using a polytetramethylene adipamide-based polymer having a relative viscosity of 2.6 to 4.0 as a polymer when producing a polyamide-based ultrafine fiber nonwoven fabric by the melt blown method. Flow from melting temperature to 2
The high-pressure air flow of 0 to 50 ℃ higher temperature pulls and thins it,
After cooling, it is collected and deposited on a moving collecting surface to form a web, and then the obtained web is subjected to a high-pressure liquid flow treatment so that the constituent fibers are entangled three-dimensionally with each other. Method for manufacturing ultrafine fiber nonwoven fabric.