JPH0765263B2 - Open nonwoven fabric - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a non-woven fabric which exhibits high performance as a heat insulating material by specifying the size / shape characteristics and structure of constituent fibers.

(Prior Art) With the increasing demand for highly functional materials, nonwoven fabrics using fine denier fibers have been put into practical use. In particular, a nonwoven fabric using ultrafine fibers obtained by randomly opening single fibers by a jet spinning method or the like has been obtained. For example, the non-woven fabrics described in JP-B-44-22525, JP-B-44-25870 and JP-B-44-25872 are one example. However, the nonwoven fabrics obtained by these methods are homogeneous, but are not satisfactory in terms of heat retention, bulkiness, softness and the like. As another proposal for coping with such a problem, a nonwoven fabric using ultrafine fibers has been proposed (Japanese Patent Publication No. 53-41577, Japanese Unexamined Patent Publication No. 54-134177, etc.), and it is expected that the thermal insulation property is improved. However, the non-woven fabric obtained by these methods is difficult to avoid the occurrence of beads in manufacturing,
The texture tends to be lowered, and further, the modulus of the fiber is further reduced by the heat-setting treatment which is carried out for preventing shrinkage and maintaining the structure after being formed as a non-woven fabric product, and further the anti-compression property of the non-woven fabric is improved. There is also the problem of getting worse.

As another proposal of non-woven fabric, it has been proposed to make a fiber having a flat cross section as a burst fiber by flash spinning (JP-A-48-93725, JP-A-50-101609 and JP-A-52-42917). )ing. However, the non-woven fabric obtained by these methods is a cut single fiber from the viewpoint of manufacturing, and has a problem that the heat retaining property is remarkably low when viewed from the heat retaining property because the structure is paper-like.

(Problems to be Solved by the Invention) The present invention has been made by paying attention to the above-mentioned problems, and the purpose thereof is to provide a large number of fibers found in the fine denier fibers obtained by the conventional technique. In order to prevent deterioration in heat retention due to the converging structure of the above, a so-called unopened part blocking structure between the single fibers, and to improve the shape retention property in the case of a non-woven fabric, low shrinkage for improving the shape retention property It is intended to provide a non-woven fabric which has a high yield and prevents the formation of felt and can maintain the bulkiness and the anti-compression property.

(Means for Solving the Problems) The present invention that has been able to achieve the above object is composed of a melt-blown non-woven fabric in which continuous fibers that have been individually opened are entangled with each other, and the non-woven fabric is a single fiber. The fineness is 0.1 denier or less, and the surface area increase ratio F given by the following formula of monofilament is 1.
The gist of the invention is an open nonwoven fabric made of synthetic fibers having 15 or more modified cross sections.

(Operation) The single yarn fineness of the synthetic fiber constituting the melt-blown nonwoven fabric in which the continuous fibers are individually entangled and entangled with each other according to the present invention must be 0.1 denier or less, and the single yarn cross section has an irregular shape. The surface increase ratio is 1.15 or more, preferably 1.30 or more. This continuous synthetic fiber is in the opened state, and is characterized in that it constitutes a melt-blown nonwoven fabric in which single fibers are entangled with each other.Unlike the conventionally known melt-blown nonwoven fabric, the continuous fiber is opened. In a melt-blown nonwoven fabric which is woven and in which the single fibers are entangled with each other and retains its shape, due to the synergistic effect of these three conditions, bulkiness, remarkably good heat retention, and favorable durability are exhibited.

The fineness of the synthetic fibers constituting the nonwoven fabric according to the present invention is 0.1
If it is thicker than the denier, the boundary layer with air is lowered, the heat retaining property is deteriorated, and the drape property and softness are deteriorated due to the modified cross-section effect, which is not preferable. If the fineness becomes too thin, the single fibers themselves that make up the structure easily deform easily with a weak force, so even if the effect of bending bending is imparted by the modified cross section, the bulk durability will decrease slightly. More preferably, it is 0.05 denier to 0.005 denier. The cross section of the synthetic fiber constituting the non-woven fabric according to the present invention is different from the fiber cross section constituting the conventionally known melt blown non-woven fabric, as compared with the round cross-section fiber due to the modified cross-section, the increasing surface area increase ratio is 1.15. As described above, the surface area increase ratio of 1.30 or more and less than 1.15 is not preferable because the heat retention is less improved as compared with the round cross-section fiber. When the surface area increase ratio of the fiber is increased, the boundary layer between the fiber and the air is remarkably increased due to the synergistic effect with the ultra-thinning, and the heat retaining property is remarkably improved. In particular, since the volume occupied by the single fibers is increased due to the modified cross-section, bulkiness is also imparted, the air content of the heat retaining layer is also increased, and the heat retaining property is improved by a synergistic effect.

Here, the larger the surface area increase ratio F, the more preferable it is, but it is estimated that the limit is about 10 from the viewpoint of manufacturing.

The cross-sectional shape of the synthetic fiber is not particularly limited, The shape of which the second moment of inertia is high has excellent anti-compression property, and even if the firching effect of wearing and the firching effect of washing and cleaning are given as external force, the fibers become karami and felt. This is particularly preferable because the durability is remarkably improved by preventing this.

The fibers constituting the melt-blown nonwoven fabric according to the present invention need to be individually opened unlike the conventionally known melt-blown nonwoven fabric in which most of the single fibers are fused. By opening the fibers, the air content, the increase and the effective utilization rate of the boundary layer are improved, and the heat retaining property is remarkably improved.

Sea-island fibers and a large number of bundled release-type fibers, even if composed of the same fiber of the present invention, the lower utilization rate of the boundary layer,
The lowering of the air content is not preferable because the heat retaining property is significantly lowered. A preferable opened state is a fiber bundle of a large number (5 or more) bundled with a single fiber interval of 5 μm or less and a length of 10 or more.
The number of continuous lines of 0 μm or more is 10 or less per 10,000 μm ² .

A method for obtaining such a preferable fiber state in a nonwoven fabric composed of continuous fibers can be achieved only by a melt blow method under special conditions as described later.

The synthetic fiber constituting the nonwoven fabric according to the present invention is not particularly limited as long as it is a synthetic polymer capable of melt spinning such as polyester, polyamide polyolefin, polyacrylonitrile, and polyvinyl chloride, but is preferably polyester, polyamide, wholly aromatic. Examples thereof include those capable of imparting characteristics such as relatively high modulus, heat resistance, chemical resistance, and weather resistance, such as group polymers.

Another preferable property of the fiber constituting the nonwoven fabric according to the present invention is that the initial tensile resistance is 15 g / denier or more, more preferably 20 g / denier or more, since the compression resistance can be maintained.

Further, the structure is preferably such that the sheath portion is oriented and crystallized and the inside is amorphized, the specific gravity and orientation degree are low, and the crystal size is high. As a result, the heat shrinkage when formed into a web is low, the dimensional stability is good, the modulus does not decrease due to the heat shrinkage, the durability is excellent, and the weight can be reduced. The thick denier yarn content of monofilament denier of 10.1 denier or more is preferably 5% or less, and the content of 10% or more is a boundary layer with an air layer per unit mass although the air content increases due to an increase in porosity. Is lowered and the heat retaining property is lowered, which is not preferable.

Another preferable characteristic of the nonwoven fabric of the present invention is that it has a form in which single fibers are not adhered to each other as much as possible in order to impart properties of being bulky, soft and having good drapeability. When adhering as needed, it is preferable to perform minimal adhering so that bulkiness, softness, and drapeability can be maintained.

Particularly preferably, the single fibers are entangled with each other to form a nonwoven fabric.

Even in such an aggregate, the nonwoven fabric of the present invention has low shrinkage, and thus has good dimensional stability, durability and wash resistance.

The apparent bulk density of the nonwoven fabric according to the present invention is 0.1 g in terms of heat retention.
/ cm ³ or less is preferable, and 0.5 g / cm ³ or more is not preferable because the heat retaining property is poor.

The nonwoven fabric according to the present invention can be manufactured by the method described below.

The nonwoven fabric according to the present invention can be obtained by a melt blow method under special conditions. The melt blow method itself is known as described in, for example, JP-A-59-26581, but even if the known method is applied as it is, a fine denier fiber satisfying the above-mentioned required characteristics cannot be obtained. In carrying out this, for example, as shown in FIG. 2, it is necessary to use an orifice having a modified nozzle hole. As spinning conditions, in order to obtain continuous fibers with a fine denier and a non-fused cross-section with irregular profile, the spinning temperature is set to 10 ± 5 ° C. higher than the melting point of the raw resin, and the traction fluid temperature is also set to the above value. It is necessary to set the temperature 20 ± 5 ° C. higher than the melting point to uniformly stretch the yarn with a high melt viscosity having a deformed cross section without relaxing the deformed cross section with a traction fluid at a low temperature. It is desirable to set the flow velocity of the traction fluid that gives the traction force necessary for the extension for fine denier and for low shrinkage and high modulus by oriented crystallization to around Mach 1. For example, when polyethylene terephthalate (melting point 265 ° C) is used as the raw material resin, the most preferable conditions are a spinning temperature of about 275 ° C and a traction fluid temperature of about 275 ° C. The discharge amount per single hole may be arbitrarily determined according to the target fiber diameter, bulk density, etc.
0.1 to 0.01 g / min for obtaining fiber diameters of less than μm,
It is more preferably 0.05 to 0.02 g / min.

A fiber group spun under such conditions is appropriately entangled with each other while being hung down while being three-dimensionally crossed on a sucked drum or net to form a nonwoven fabric. The distance between the spinning nozzle and the drum or net is such that the fibers are not closely entangled with each other to form a string, that is, the fibers are three-dimensionally crossed and laminated due to the spread and turbulence of the entrained traction fluid. It is set at a sufficient distance, for example, about 30 to 60 cm. If necessary, the non-woven fabric can be adjusted in apparent bulk density by lightly pressing with a heating roller or the like or by embossing.

The following will further clarify the constitution and action and effect of the present invention with reference to examples. The physical properties and the like of the non-woven fabric fibers defined in the present invention are values measured by the following methods.

Single-fiber cross-sectional area: S 300 fibers or more constituting the non-woven fabric are taken out from the non-woven fabric and aligned, and the slice is made by embedding this in epoxy resin or acrylic resin, and the slice is examined by an electron microscope from 2000 to Photographed at 5000 times, randomly selected 100 pieces showing the single fiber cross section from the enlarged photograph (magnification about 10,000 to 20,000 times), measured the single fiber cross-sectional area (Si), Is calculated as an average value.

Single fiber fineness: D Average single fiber cross-sectional area S obtained from the above and density gradient tube method (30
Using the value of specific gravity SG (n = 5) measured at (° C.), D (denier) is calculated by the following equation.

Single fiber density D = S × SG × 900000 (Denier) Surface area increase ratio: F Similar to the case of obtaining the single fiber cross-sectional area, 300 or more fibers constituting the non-woven fabric are taken out and aligned, and then the epoxy resin or 100 pieces showing a single fiber cross section from the enlarged photograph (magnification of about 10,000 to 20,000 times) taken by observing the section with an electron microscope at 2000 to 5000 times. Is randomly selected, and the outer peripheral length (li) of the single fiber cross section is measured, and the average outer peripheral length is calculated by the following formula.

Next, using the value of the average cross-sectional area S obtained above, the surface area increase ratio F is obtained by the following equation.

Evaluation of open state The non-woven fabric was photographed with an electron microscope at 100 to 3000 times and taken as an enlarged photograph (magnification: 4000 to 10,000 times).
It is preferable that 5 or more fiber bundles that are bundled to m or less are continuous with a length of 100 μm or more and 10 or less per 10,000 μm ² and the others are opened (A), and if 50 or less, the others are opened. In the present invention, a fiber (B) that has been fibrillated and a fiber (C) that has been bundled with almost no fiber being opened are referred to as an opened fiber in the present invention.

Initial tensile resistance value: Twenty single filaments are randomly drawn, and the filaments are spun into one strand, and then measured according to JIS 11074 ('65).

Thread diameter unevenness (CV) From the single fiber cross-sectional area (Si) and the single fiber fineness D obtained in the same manner as above, the variation is obtained by the following formula.

Thermal resistance value Measured according to ASTM-D-1518 Longitudinal and transverse shrinkage of non-woven fabric Cut the non-woven fabric into 25 cm x 25 cm, along the periphery of the cut piece.
Fill in a 20 cm x 20 cm frame. One point outside the frame of the cut piece was held with a clip and hung in a hot air dryer, heat treated at 160 ° C for 30 minutes, then cooled to a room temperature atmosphere (20 ° C x 65% RH) in 30 minutes, and then lengthwise. Length (It: cm) and lateral length (Im: c)
From m), the longitudinal shrinkage [SHD (T)] and the lateral shrinkage [SHD (M)] are calculated by the following equations.

(Example) Example-1 Polyethylene terephthalate having an intrinsic viscosity of 0.65 was used at 275 ° C (corresponding to the orifice hole) by using the melt blow nozzle shown in Fig. 1 (1 is an orifice hole, 4 is a temperature detecting end). Diameter φ0.4mm, shown in Fig. 2 (e) Spinning at a discharge rate of 0.10 g / minute per hole, detection end 4
The heated air whose temperature is 275 ° C is operated at a pressure of 2.2 kg / cm ² , and the spun fibers are collected on a net that operates at a speed of 1 m / min at a position 40 cm away from the nozzle discharge end, and a modified cross section is formed. A non-woven fabric composed of the ultrafine fibers was obtained.

The characteristics of the obtained non-woven fabric are shown in Table 1. Thermal resistance value is 13.5
It is clo / cm, which means that this nonwoven fabric has excellent heat retention.

This nonwoven fabric was excellent in drape, soft and bulky. As a result of using this non-woven fabric as a batting, a cold-proof jacket was made and worn for a long time in a freezer at -20 ° C. As a result, excellent heat retention was exhibited and a comfortable wearing feeling was obtained.

Further, it was endured by repeated dry cleaning, and no deterioration in heat retention and bulkiness was observed.

Comparative Example-1 The orifice shape is shown in FIG.
A nonwoven fabric was prepared under the same conditions as in Example 1 except that 3 mm was used. The characteristics of the obtained non-woven fabric are shown in Table 1. The nonwoven fabric was inferior in heat retention.

Comparative Example-2 Using polybutylene terephthalate having an intrinsic viscosity of 0.8, the spinning temperature was 285 ° C, the temperature and pressure of the drawing fluid were 290 ° C, and 1.3 kg /
A nonwoven fabric was prepared under the same conditions as in Comparative Example-1 except that the collecting position was cm ² and the take-up position was 15 cm from the nozzle discharge end. The characteristics of the obtained non-woven fabric are shown in Table 1. Since this nonwoven fabric was fused, it had a low bulk, was inferior in drape property and softness, and was inferior in heat retention property. Also, the thermal stability was poor.

A cold-protection jacket made using this non-woven fabric is inferior in dry cleaning resistance and has batting.
In addition, felting also occurred.

Comparative Example-3 An orifice having the shape shown in FIG. 2 (c) and a round equivalent diameter of φ0.4 mm was used, and spinning was performed at a spinning temperature of 285 ° C. and a single hole discharge rate of 0.2 g / min. Fluid temperature and pressure 285
A non-woven fabric was prepared under the same conditions as in Example 1 except that the temperature was 1.8 ° C. and the pressure was 1.8 kg / cm ² . The characteristics of the obtained non-woven fabric are shown in Table 1. This non-woven fabric had poor softness and drape, poor bulkiness and poor heat retention. This non-woven fabric was also inferior in dry cleaning resistance.
In addition, felting also occurred.

Comparative Example-4 A non-woven fabric was prepared under the same conditions as in Example-1, except that the nozzle (equivalent diameter of circle: 0.4 mm) shown in Fig. 2 (i) was used as the orifice shape. The characteristics of the obtained non-woven fabric are shown in Table 1. This non-woven fabric, which is out of the requirements of the present invention, was inferior in heat retention.

Comparative Example-5 Polyester with Intrinsic Viscosity of 0.65 and 6. Nylon with Relative Viscosity of 2.0 at 285 ° C at Nylon / Polyester Discharge Ratio (0.1g / min ・ hole) / (0.1g / min ・ hole) Spin off, pick up at 1300m / min, heating roller at 80 ℃
It was stretched 2.5 times, taken up by an aspirator, and collided and laminated on a net 10 cm below it to prepare a non-woven fabric composed of peelable fibers. The characteristics of the obtained non-woven fabric are shown in Table 1.

This nonwoven fabric, which is out of the scope of the present invention, has a poor open state, and
It was inferior in heat retention and inferior in softness, drapeability and bulkiness.

Comparative Example 8 Spinning temperature is 310 ° C., heated air temperature is 400 ° C., pressure is 4 kg / cm ^2.
However, the non-woven fabric obtained under the same conditions as in Example 1 was composed mostly of shot fibers having beaded cut ends and fused, and the cross section of the fibers was a round cross section. This non-woven fabric is stiff and stiff, soft, drapeable,
The bulkiness was remarkably inferior, and the heat resistance value was 2.0, which was also inferior in heat retention. Further, the heat shrinkage was 70% or more in both length and width, and the heat stability was poor.

(Effects of the Invention) The present invention is configured as described above, and by specifying the diameter of fibers constituting the nonwoven fabric, the cross-sectional shape, and the opened state of the single fibers when the nonwoven fabric is formed, it is appropriate throughout It has become possible to provide a non-woven fabric having a uniform size free space, particularly excellent heat retention, anti-compression property, and excellent dimensional stability.

Further, this non-woven fabric is excellent in dry cleaning resistance, soft feeling and drape in addition to the above characteristics, and not only can exhibit excellent performance as a special function heat insulating material, mainly as a heat insulating material for clothing, Various filter applications,
It can be widely used for composite applications and sanitary materials.

[Brief description of drawings]

FIG. 1 is a cross-sectional view and a plan view of essential parts showing a melt blow nozzle used in Examples. FIG. 2 is a diagram showing a fiber cross section corresponding to the orifice shape of the melt blow nozzle used in the example of the present invention. 1: Orifice hole 2: Lip 3: Molten polymer introduction hole 4: Temperature detection end F: Inflow direction of traction fluid

Claims (4)

[Claims] 1. A melt-blown non-woven fabric in which continuous fibers that have been individually opened are entangled with each other. The non-woven fabric has a fineness of single fiber of 0.1 denier or less, and a surface area increase ratio F given by the following formula of the single fiber. Is an opened nonwoven fabric characterized by comprising synthetic fibers having a modified cross section of 1.15 or more. 2. The spread nonwoven fabric according to claim 1, wherein the surface area increase ratio is 1.30 or more. 3. The spread nonwoven fabric according to claim 1 or 2, wherein the synthetic fiber has an initial tensile resistance of 15 g / denier or more. 4. The spread nonwoven fabric according to any one of claims 1 to 3, wherein the apparent bulk density of the nonwoven fabric is less than 0.5 g / cm ³ .