JPH06116854A - Specific nonwoven fabric - Google Patents

Abstract

PURPOSE:To obtain nonwoven fabric suitable for heat insulating material, high- temperature insulation, having excellent bulkiness, heat retaining properties, water vapor permeability and heat dissipation, comprising ultra-fine fibers. CONSTITUTION:Ultra-fine fibers having 10mum or shorter average fiber diameter are entangled with thicker crimping fibers to give nonwoven fabric having an inclination of water vapor transmission in the section direction. The nonwoven fabric is lightweight, has excellent heat retaining properties, water vapor permeability and is suitable for heat insulating material, high-temperature insulation, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a special non-woven fabric containing ultrafine fibers, which is suitable for heat-resistant materials, heat-insulating materials, etc., which are rich in bulkiness and excellent in moisture permeability and moisture release per thickness.

[0002]

2. Description of the Related Art Nonwoven fabrics made of ultrafine fibers, especially ultrafine fibers obtained by the melt-blowing method are excellent in heat insulating property, bacterial barrier property, filter property and the like, and are utilized in various applications by utilizing these characteristics. For the melt-blowing method, see Industrial and Engineering Chemi
stry) Volume 48, No. 8 (1342-1346), 195
In 6 years the basic device and method were disclosed. Also,
JP-B-56-33511 and JP-A-55-142
Japanese Patent No. 757 discloses a method for producing ultrafine fibers such as polyolefin and polyester. On the other hand, the following are known as non-woven fabrics in which thick short fibers are mixed with ultrafine fibers. That is, in US Pat. No. 3,016,599, 1
A batting in which microfibers of less than μm and staple fibers of 1 d or more are uniformly mixed is disclosed. Japanese Patent Publication No. 61-30065 discloses a microfiber and a crimped staple fiber having a diameter larger than 30 cm. Elastic fiber webs for thermal insulation having a bulkiness of ³ / g are disclosed. Also, JP-A-59-1837
Japanese Unexamined Patent Publication No. 23 discloses a nonwoven fabric in which staple synthetic fibers and cotton fibers are uniformly mixed with an ultrafine fiber web.

[0003]

Nonwoven fabrics composed of only ultrafine fibers, especially webs of ultrafine fibers obtained by the melt-blowing method, are porous materials having a very small pore size, and therefore have a heat insulating property, a bacterial barrier property and a filter. However, since single fibers are generally linear, there is a problem that bulkiness is poor. For this problem, the above-mentioned US Patent No. 301
No. 6599 and Japanese Patent Publication No. 61-30065 disclose mixing of crimped staple fibers with ultrafine fibers to improve bulkiness and obtain excellent heat insulation. Further, JP-A-59-183723 discloses an attempt to improve bulkiness and improve wiper performance by uniformly mixing thick crimped staple fibers with ultrafine fibers. The properties required of a heat insulating material for clothing, which is one of the heat insulating materials, include improvement of moisture permeability and moisture release in addition to improvement of heat retention. For improvement of heat retention, US Patent No. 3016
599, JP-B-61-30065, JP-A-59-
It is effective to increase the bulkiness as disclosed in Japanese Patent No. 183723. However, for improvement of moisture permeability and moisture release, Japanese Patent Publication No. 1-919
Although it is improved by optimizing the lamination of the moisture absorbing layer and the moisture releasing layer as in Japanese Patent No. 0, the problem is seen in terms of cost. An object of the present invention is to provide a special non-woven fabric which is lightweight and has an excellent heat retaining property per thickness and a combination of performances such as improvement of moisture permeability and moisture releasing property, which is excellent as a heat insulating and heat insulating material.

[0004]

[Means for Solving the Problems] In order to achieve the above-mentioned problems, as a result of intensive studies, the following means have been reached. That is, according to the present invention, two or more kinds of fibers having an average fiber diameter of about 10 μm or less and having an average fiber diameter larger than the ultrafine fibers and at least one kind of crimpability are mixed and entangled with each other. The object is achieved by a non-woven fabric, which is a special non-woven fabric having a hygroscopic gradient in the cross-sectional direction. The ultrafine fibers of the present invention are polypropylene, polyolefin such as polyethylene, polyethylene terephthalate, polyester such as polybutylene terephthalate,
Polyamides such as nylon 6 and nylon 66 and copolymers thereof, polyvinyl chloride, acrylic and acrylic copolymers, polystyrene, polyarylene sulfide, polysulfone, inorganic fibers and the like. In the present invention, polyolefins such as polypropylene and polyethylene, polyesters such as polyethylene terephthalate and polybutylene terephthalate are preferably selected from the viewpoints of weight reduction and cost.

The average fiber diameter of the ultrafine fibers of the present invention is about 10 μm.
It is preferably m or less, and more preferably in the range of 1 to 8 μm. When the average fiber diameter is larger than about 10 μm, the strength of the nonwoven fabric is high, but on the other hand, the heat insulating property is inferior, which is not preferable. The fibers mixed with the ultrafine fibers in the nonwoven fabric of the present invention preferably have a larger average fiber diameter than the ultrafine fibers. If the average fiber diameter is smaller than that of the ultrafine fibers, the bulkiness is lowered and the heat insulating property is deteriorated, which is not preferable. As the fibers to be mixed with the ultrafine fibers, it is possible to use two or more kinds of fibers having different hygroscopic properties such as polyester, polyolefin, acrylic, polyamide, rayon, polynosic, acetate, wool, cotton, and composite fibers that can be manufactured. is necessary. This is because the difference in hygroscopicity in the cross-sectional direction of the fibers mixed with the ultrafine fibers helps the migration of water. It is preferable that at least one kind of fibers mixed with the ultrafine fibers has a crimpability of 5% or more. When the crimp ratio of the fibers mixed with the ultrafine fibers is less than 5%, the effect of improving the bulkiness is small and the heat insulating property is poor, which is not preferable.

The mixing ratio of the fibers mixed with the ultrafine fibers in the nonwoven fabric of the present invention is preferably 10 to 90% by weight, more preferably 30 to 80% by weight. If the mixing ratio is less than 10 wt%, the heat insulation and moisture permeability will decrease,
If it exceeds 90 wt%, the static air layer due to the ultrafine fibers is reduced and the heat insulating property is reduced, which is not preferable. The fibers mixed with the ultrafine fibers in the nonwoven fabric of the present invention may be short fibers or long fibers. The length of the short fibers is preferably 3 to 100 m in order to mix them evenly in the ultrafine fibers.
m, especially 10 to 80 mm is preferable. Further, the nonwoven fabric of the present invention may contain other components such as powder.

The method for obtaining the ultrafine fibers of the present invention is not particularly limited, such as the melt blow method and the flash spinning method, but the melt blow method is particularly preferable. As a method for obtaining the nonwoven fabric of the present invention, a molten thermoplastic resin is blown with a high-speed heating gas to form a fiber stream composed of ultrafine fibers having an average fiber diameter of about 10 μm or less, and defibrated fibers having different hygroscopic properties are obtained. The fiber stream is collected while being inserted into the fiber stream from both sides of the fiber stream separately. As a method of defibrating the fibers mixed with the ultrafine fibers, there are a method of using a Rickelin roll or the like, a method of using sliver-like fibers with a combing roll, and the like. Further, the nonwoven fabric of the present invention may be subjected to various joining treatments after mixing the ultrafine fibers with the multifibers.

[0008]

EXAMPLES The present invention will be described in more detail with reference to the following examples. The definitions and measuring methods of various properties shown in Examples and Comparative Examples are described below. -Average fiber diameter (μm) Take 10 photographs with a scanning electron microscope at 10 arbitrary points of the sample. The diameter of any 10 fibers is measured per photograph and this is done for 10 photographs.
A total of 100 fiber diameters were measured and the average value was calculated. -Thickness (mm) Using a thickness compression tester, measurement was performed 5 times under a load of 1 g / cm ² , and an average value was calculated.・ Tensile strength (g / unit weight) Take a 20 mm width × 160 mm length as a sample and use Tensilon, gripping length 100 mm, load capacity 100 kg,
The measurement was performed 5 times in length and width at a tensile speed of 100 mm / min, and the average value was converted per 1 cm per unit basis weight (g / m ² ). Crimping rate (%) Take fibers at any 10 points of the sample and straighten the crimp length a [bend of the sample fiber having a large radius (2 mg
/ D under load) measurement] and end crimp length b of fiber [measurement after straightening sample fiber sufficiently (under load of 50 mg / d)]
Was calculated | required and it substituted by 100 (ba) / b and converted. -Mixing rate (%) The weight of the mixed fibers was divided by the total weight of the non-woven fabrics to obtain 100 times the value.・ Heat retention ASTM heat retention (constant temperature method) tester, etc.
The power consumption required to maintain the temperature was measured three times, and the average value was converted into a claw value by the following formula. 1 claw value is environmental condition 21 ℃, 50% RH, air flow 10cm / sec
It is the heat insulation of clothing that is comfortable enough for a person who sits down comfortably, and the metabolic energy at that time is 50.
kcal / m @ 2 / hr, skin temperature is 33.degree. Claw value = Δt / 0.18Q (Δt: difference between hot plate temperature and ambient temperature (° C.), Q: power consumption (kcal / m ² · hr))・ Hygroscopicity gradient The sample was separated into two layers on the front and back sides, and the amount of moisture absorption after 1 hour when each sample was transferred from 71% RH to 97% RH at 27 ° C was obtained from three weight change measurements. The value obtained by dividing the value by the smaller value was used as the hygroscopicity gradient. Moisture transfer (moisture permeability, moisture release,% RH) Moisture transfer was expressed as the maximum humidity in clothes. The maximum in-cloth humidity was measured by using the in-cloth climate simulating apparatus and method disclosed in JP-A-58-021164.
The environmental humidity conditions were 20 ° C., 65% RH, the temperature of the simulated skin was set to 35 ° C., and the average value of three measurements was calculated.

Example 1 and Comparative Examples 1, 2, 3, 4 Polypropylene was spun by a melt blow method to obtain a group of ultrafine fibers having an average fiber diameter of 1.9 μm. Fiber diameter 25μm,
A polyethylene terephthalate hollow fiber with a fiber length of 64 mm and a crimping rate of 23% is made into a sliver shape, and a large number of this sliver is defibrated with a combing roll to cause short fibers to fly and mixed from one side just below the spinning nozzle of the ultrafine fiber group Let At the same time, a polynosic fiber having a fiber diameter of 15 μm, a fiber length of 38 mm, and a crimping rate of 8% is formed into a sliver shape, and short fibers are made to fly while defibrating a large number of this sliver with a combing roll to spun the ultrafine fiber group. The mixture was mixed from directly below the nozzle and on the opposite side. A web was obtained by collecting this mixed fiber group in the form of a moving net provided below. The fibers that make up this web have no lumps and are dispersed substantially in the form of short fibers. There are many polyethylene terephthalate hollow fibers, and there are few polynosic fibers, and there are many polynosic fibers and there is little polyethylene terephthalate hollow fibers. The fibers mixed in the direction were gradually different. The mixing ratio of the fibers mixed with the ultrafine fibers is about 40% for polyethylene terephthalate hollow fibers and about 3 for polynosic fibers.
It was 0%, which was about 70% in total. This web has a diameter of 5
mm and a pitch of 50 mm was used to perform a joining treatment with an ultrasonic fusion machine to obtain a composite nonwoven fabric (Example 1). As a comparative example, a nonwoven fabric (Comparative Example 1) obtained in the same manner as described in Example 1 except that fibers were not mixed and only ultrafine fibers were mixed, 70% of polyethylene terephthalate hollow fibers were mixed, and polynosic fibers were not mixed. A composite non-woven fabric (Comparative Example 2) obtained in the same manner as described in Example 1 except for the above, a plurality of slivers in which polyethylene terephthalate and polynosic fibers are uniformly mixed are defibrated with a combing roll while flying short fibers. A composite non-woven fabric (Comparative Example 3) obtained in the same manner as described in Example 1 except that the ultrafine fiber group was mixed from both sides immediately below the spinning nozzle (Comparative Example 3), a fiber diameter was used instead of the polyethylene terephthalate hollow fiber of Example 1. 24 μm, fiber length 64
Table 1 and Table 2 also show the physical properties of the composite nonwoven fabric (Comparative Example 4) obtained in the same manner as described in Example 1 except that polynosic fibers having a mm and a crimping rate of 8% were mixed.

[0010]

[Table 1]

[0011]

[Table 2]

As is clear from Tables 1 and 2, it was found that the product of the present invention exhibits excellent performance in terms of heat retention and moisture permeability and moisture release as seen from the maximum humidity in clothes.

Example 2, Comparative Examples 5 and 6 Polyethylene terephthalate was spun by a melt blow method to obtain a group of ultrafine fibers having an average fiber diameter of 3.5 μm. Directly below the spinning nozzle of the ultrafine fiber group where the polyethylene terephthalate hollow fiber having a fiber diameter of 25 μm, a fiber length of 64 mm and a crimping rate of 23% is used as a card web, and the short fibers are made to fly while defibrating the web with a Rickelin roll. Mixed from one side. At the same time, a polynosic fiber having a fiber diameter of 15 μm, a fiber length of 38 mm, and a crimping rate of 8% was used as a card web, and short fibers were made to fly while defibrating this web with a Rickelin roll, immediately below the spinning nozzle of the ultrafine fiber group. Mix from the other side. A web was obtained by collecting this mixed fiber group in the form of a moving net provided below. The fibers mixed with this web are dispersed in a substantially single fiber form without lumps, and there are many polyethylene terephthalate hollow fibers, the side with few polynosic fibers and the side with many polynosic fibers and the side with few polyethylene terephthalate hollow fibers. The fibers mixed in were gradually different. The mixing ratio of fibers mixed with the ultrafine fibers was about 40% for polyethylene terephthalate hollow fibers and about 30% for polynosic fibers, which was about 70% in total. This web has a diameter of 5 mm and a pitch of 5
Bonding treatment was performed with a 0 mm ultrasonic fusion machine to obtain a composite nonwoven fabric (Example 2). As a comparative example, it was obtained in the same manner as described in Example 2 except that the mixing ratio of polyethylene terephthalate hollow fiber and polynosic fiber was different.
Physical properties of a composite non-woven fabric containing about 5% polyethylene terephthalate hollow fibers and about 3% polynosic fibers (Comparative Example 5) and a composite non-woven fabric containing about 53% polyethylene terephthalate hollow fibers and about 42% polynosic fibers (Comparative Example 6) The results are shown in Table 2 above and Table 3 below. As is clear from Table 2, it was found that the product of the present invention exhibits excellent performances in heat retention, moisture permeability and moisture release.

[0014]

[Table 3]

Example 3 and Comparative Example 7 Polyethylene terephthalate was spun by a melt blow method to obtain a group of ultrafine fibers having an average fiber diameter of 3.5 μm. A nylon 6 monofilament having a fiber diameter of 25 μm was caused to fly by heating and pressurizing air, and mixed from one side immediately below the spinning nozzle of the ultrafine fiber group. At the same time, the fiber diameter is 25 μm,
Polyethylene terephthalate having a fiber length of 64 mm and a crimping rate of 23% and a fiber diameter of 15 μm, a fiber length of 38 mm and a crimping rate of 8%
A large number of slivers in which the polynosic fibers of 1. were uniformly mixed were defibrated with a combing roll, and short fibers were made to fly to mix the fine fibers from the reverse side directly below the spinning nozzle.
A web was obtained by collecting this mixed fiber group in the form of a moving net provided below. The fibers that make up this web have no lumps and are dispersed in a substantially single fiber state, with a large amount of nylon 6 monofilament, a side with few polyethylene terephthalate hollow fibers and polynosic fibers, and a lot of polyethylene terephthalate hollow fibers and polynosic fibers. The fibers mixed in the cross-sectional direction on the side where the amount of 6 monofilaments was small were gradually different. The mixing ratio of ultrafine fibers is about 10% for nylon 6 monofilament and about 30 for polyethylene terephthalate hollow fiber.
%, And polynosic fiber was about 30%, which was about 70% in total. This web was joined by an ultrasonic fusion machine having a diameter of 5 mm and a pitch of 50 mm to obtain a composite nonwoven fabric (Example 3). As a comparative example, all the fibers mixed are nylon 6
The physical properties of the composite nonwoven fabric (Comparative Example 7) obtained in the same manner as described in Examples except that it is a monofilament are also shown in Table 2 and Table 4 below.

[0016]

[Table 4]

As is clear from Tables 2 and 4, even if only nylon 6 monofilament having no crimp is mixed in the ultrafine fibers, not only the bulkiness cannot be efficiently obtained but the heat retaining property cannot be obtained, but also the hygroscopic property is obtained. Since there is no gradient, the moisture permeability and moisture release properties are not very good. On the other hand, it was found that the product of the present invention exhibits excellent heat retention and moisture permeability per thickness.

Example 4 Just under mixing short fibers into the ultrafine fibers of Example 2, polyester powder having a melting point of 120 ° C. was fed by air to mix the ultrafine fibers with about 10% and ultrasonic melting. A composite non-woven fabric was obtained in the same manner as in Example 2 except that the fibers constituting the non-woven fabric and the hot-melt powder were heat-sealed by using hot air at 130 ° C. after performing the joining process with the machine (Example 4). .
The physical properties are shown in Table 2. As is clear from Tables 2 and 4, the components other than the fibers, for example, the fibers constituting the non-woven fabric are hot-melted by using the hot-melt powder to heat-bond the hot-melt powder, and the heat-retaining property, the moisture permeability and the release property per unit thickness are obtained. It was found that the wettability is excellent and the tensile strength is also improved.

[0019]

EFFECT OF THE INVENTION Since the nonwoven fabric of the present invention is constructed as described above, it is possible to obtain a one-layer type heat insulation material which is lightweight and has excellent heat retention and performance such as moisture permeability and moisture release. I can do it now. Since it is a single layer type, it does not require pasting and is excellent in cost.
Therefore, the industrial significance of the present invention is great.

Claims (1)

[Claims] 1. A non-woven fabric in which two or more kinds of fibers having an average fiber diameter of about 10 μm or less and having an average fiber diameter thicker than the ultrafine fibers and at least one type of which has crimpability are mixed and entangled with each other. A special nonwoven fabric having a hygroscopic gradient in the cross-sectional direction.