CN103459695B - The excellent non-woven fabrics of heat endurance, flexibility - Google Patents

Abstract

The non-woven fabrics that the present invention provides topsheet, back sheet or the side collection portion of the absorbent commodity for being suitable for being used in hygienic material and heat endurance is high, flexibility is excellent and processability is also good.The present invention relates to a kind of non-woven fabrics, it is characterised in that it is formed by polyolefin series fiber, the crystallite dimension of the polyolefin series fiber is more than 15nm and below 50nm, and the bending pliability of the non-woven fabrics is more than 5mm and below 100mm.

Description

Nonwoven fabric with excellent thermal stability and softness

technical field

The present invention relates to a non-woven fabric formed of polyolefin-based fibers which is excellent in processability and is suitable for a top sheet, a back sheet, or a side collection part of an absorbent article used as a hygienic material .

Background technique

In recent years, the popularity of disposable diapers has been remarkable, and its production has gradually surged. As a disposable diaper in this environment, it is important to reduce the loss on the production line and to stabilize the quality. In a diaper production line, if the thermal stability of the nonwoven fabric used as a raw material is low, the width dimension of the nonwoven fabric will change during the lamination process with the film, and various problems such as wrinkles and bending will occur. Furthermore, in the heat-sealing process, the non-woven fabric itself shrinks and deforms due to the influence of heat from the heat-sealing roll, causing wrinkles and bending. Therefore, a non-woven fabric with high thermal stability is required.

Conventionally, as a means of improving the thermal stability of nonwoven fabrics, methods such as increasing the thermal bonding temperature, increasing the bonding pressure, increasing the embossing area ratio, etc. are used to increase the bonding strength of the fibers of the nonwoven fabric. However, using any of these methods will increase the level of adhesion, thereby making the texture of the nonwoven fabric harder. That is, conventional methods for improving the thermal stability of nonwoven fabrics have the following problems: they are poor in flexibility when used in hygienic materials, and it is very difficult to achieve both flexibility and thermal stability of nonwoven fabrics.

The following Patent Document 1 describes that a propylene/ethylene random copolymer is used, and the ethylene content is set within a specific narrow range in order to achieve both flexibility and thermal stability. Thus, in the invention described in Patent Document 1, a nonwoven fabric is produced using extremely limited raw materials.

In addition, the following Patent Document 2 describes a method of increasing the thermal bonding temperature to reduce the thermal shrinkage rate. However, in the method described in patent document 2, the texture of a nonwoven fabric becomes hard, and it is not preferable to use it for a sanitary material.

prior art literature

patent documents

Patent Document 1: Japanese Patent Application Laid-Open No. 10-96157

Patent Document 2: Japanese Patent Laid-Open No. 2003-129364

Contents of the invention

The problem to be solved by the invention

The problem to be solved by the present invention is to provide a nonwoven fabric suitable for the top sheet, back sheet or side collection part of absorbent articles used in hygienic materials, having high thermal stability, excellent flexibility, and good processability .

solutions to problems

The inventors of the present invention conducted intensive studies and experiments in order to solve the aforementioned problems. As a result, they found that by setting the crystallite size of the polyolefin-based fibers constituting the nonwoven fabric to a specific size, the bending softness of the nonwoven fabric can be set to a certain level. In a specific range, it is possible to suppress changes in the width dimension, generation of wrinkles, and bending of the nonwoven fabric caused by the influence of heat when applying the hot melt agent in the film bonding process in the sanitary material processing process. The present invention has been accomplished by suppressing changes in width dimensions, generation of wrinkles, warping of the nonwoven fabric, etc. due to the influence of heat of the heat-sealing roll in the heat-sealing process as a subsequent process.

In addition, the inventors of the present invention have found that by setting the fiber temperature at the inlet of the pulling device and the wind speed of the pulling air to a predetermined range in the production process of the nonwoven fabric, the crystallite size will be in a specific range, thereby achieving thermal stability. The present invention has been achieved by a nonwoven fabric that is high, excellent in softness, and has good processability and can be applied to hygienic materials.

That is, the present invention is as follows.

A nonwoven fabric characterized in that it is formed of polyolefin fibers, the crystallite size of the polyolefin fibers is not less than 15 nm and not more than 50 nm, and the bending softness of the nonwoven fabric is not less than 5 mm and not more than 100 mm.

The nonwoven fabric according to the above [1], wherein the boiling water shrinkage of the nonwoven fabric is not less than 0% and not more than 3.0%.

The nonwoven fabric according to [1] or [2] above, wherein the polyolefin-based fibers are polypropylene-based fibers.

The nonwoven fabric according to any one of [1] to [3], wherein the nonwoven fabric is a long-fiber nonwoven fabric.

The nonwoven fabric according to any one of [1] to [4] above, wherein the polyolefin-based fibers have an average single-yarn fineness of 0.5 dtex to 3.5 dtex.

The nonwoven fabric according to any one of [1] to [5] above, wherein the dry heat shrinkage rate of the nonwoven fabric at 120° C. is 0% or more and 5.0% or less.

A hygienic material formed using the nonwoven fabric according to any one of [1] to [6].

The hygienic material according to the above [7], which is in the form of a disposable diaper, a sanitary napkin or an incontinence pad.

The effect of the invention

The non-woven fabric of the present invention is a non-woven fabric formed of polyolefin-based fibers, and the crystallite size of the polyolefin-based fibers is 15 nm to 50 nm, and the bending flexibility is 5 mm to 100 mm, so as to maintain flexibility properties, and good processability.

In order to suppress generation of wrinkles and warping due to heat during processing, it is important to make the crystallite size larger than a certain size. For example, even if the degree of crystallinity is the same, if a large number of small-sized crystals exist, the entire fiber shrinks. On the other hand, when the crystallite size is large, the crystal part rigidly suppresses molecular movement, and shrinkage can be suppressed.

Furthermore, in order to make processability (processing suitability) favorable, moderate flexibility is required. When the softness is too low, it is impossible to follow the fluctuations in tension during processing, the fluctuations in the peripheral speed of the roll, etc., and problems such as wrinkles and zigzagging occur.

Since the nonwoven fabric of the present invention has the aforementioned constitution, it is suitable for a top sheet, a back sheet, or a side collecting portion of an absorbent article used in hygienic materials, and has excellent processability.

Description of drawings

FIG. 1 is a schematic diagram illustrating a method of measuring bending softness.

detailed description

The present invention is described in detail below.

Examples of the polyolefin-based fibers constituting the nonwoven fabric of the present invention include fibers made of resins such as polyethylene, polypropylene, and copolymers of these monomers and other α-olefins. Among them, polypropylene fibers are preferably used because they have high strength, are not easily broken during use, and are excellent in dimensional stability when producing hygienic materials. Polypropylene may be a polymer synthesized using a general Ziegler-Natta catalyst, or a polymer synthesized using a single-site active catalyst represented by a metallocene. Alternatively, ethylene random copolymerized polypropylene may be used, and the ethylene content is preferably less than 2%, preferably less than 1%. Other α-olefins are olefins having 3 to 10 carbon atoms, specifically, propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1 -octene etc. These may be used alone or in combination of two or more. Alternatively, polyester fibers such as polyolefin fibers, polyethylene terephthalate fibers, polybutylene terephthalate fibers, polyethylene naphthalate fibers, and copolyesters may be used , Nylon-6 fiber, Nylon-66 fiber, polyamide fibers such as copolymerized nylon, polylactic acid, polybutylene succinate, polyethylene succinate and other biodegradable fibers use one or a combination of two Use more than one species. It is preferable to use only one kind. Furthermore, a core-sheath fiber having a polyolefin-based resin as a surface layer may also be used. In addition, the fiber shape may be not only ordinary round fibers, but also fibers of special forms such as crimped fibers and special-shaped fibers.

From the standpoint of strength and dimensional stability, it is particularly preferable to use homopolypropylene as the main component.

In addition, in the case of polypropylene, the lower limit of the MFR is 20 g/10 minutes or more, preferably more than 30 g/10 minutes, more preferably more than 40 g/10 minutes, and still more preferably more than 53 g/10 minutes. The upper limit is 100 g/10 minutes or less, preferably 85 g/10 minutes or less, more preferably 70 g/10 minutes or less, still more preferably less than 65 g/10 minutes. When the MFR is within this range, the fluidity of the resin is good, and a nonwoven fabric with good bending flexibility can be obtained. MFR is calculated according to Table 1 of JIS-K7210 "Melt Mass Flow Rate (MFR) and Melt Volume Flow Rate (MVR) Test Methods of Plastics - Thermoplastics", the test temperature is 230°C, and the test load is 2.16kg. out.

A nucleating agent, a flame retardant, an inorganic filler, a pigment, a colorant, a heat-resistant stabilizer, an antistatic agent, etc. may be compounded with the polyolefin fiber which comprises the nonwoven fabric of this invention.

As the bonding means when polyolefin-based fibers are bonded to produce non-woven fabrics, partial thermocompression bonding, hot air method, bonding (hot melt) method using molten components, and various other methods can be mentioned. From the viewpoint of strength , preferably partial thermocompression bonding.

The thermocompression bonded area ratio of the nonwoven fabric of the present invention is from the viewpoint of strength retention and softness to 3% to 40%, preferably 4% to 25%, more preferably 4%. % or more and 20% or less, more preferably 5% or more and 15% or less.

In addition, part of the thermocompression bonding treatment of the present invention can be performed by ultrasonic method, or by passing the web (web) through heated embossing rollers, thereby integrating the front and back, for example, needle-shaped, oval, Concave-convex patterns such as diamonds and rectangles are scattered on the entire surface of the non-woven fabric. From the viewpoint of productivity, it is preferable to use a heated embossing roll.

The average single yarn fineness of the polyolefin fibers constituting the nonwoven fabric of the present invention is preferably from 0.5 dtex to 3.5 dtex, more preferably from 0.7 dtex to 3.2 dtex, still more preferably from 0.9 dtex to 2.8 dtex. From the viewpoint of spinning stability, it is preferably 0.5 dtex or more. The finer the fineness, the more bonding points of filaments when made into a nonwoven fabric, so the strength is high and the flexibility is good. Since it is mainly used for sanitary materials, it is preferably 3.5 dtex or less from the viewpoint of the strength of the nonwoven fabric.

The basis weight of the nonwoven fabric of the present invention is 8 g/m ² to 40 g/m ² , preferably 10 g/m ² to 30 g/m ² , more preferably 10 g/m ² to 25 g/m ² Below, more preferably 10 g/m ² or more and less than 23 g/m ² . When it is 8g/m ² or more, it meets the demand for the strength required for non-woven fabrics used in sanitary materials. On the other hand, when it is 40g/m ² or less, it meets the softness of non-woven fabrics used in sanitary materials. It gives the impression of being thicker in appearance.

The nonwoven fabric of the present invention has a crystallite size of 15 nm to 50 nm, preferably more than 20 nm and 50 nm, more preferably 25 nm to 40 nm. When the crystallite size is 15 nm or more, thermal stability is good, and from the viewpoint of the flexibility of a nonwoven fabric used for sanitary materials, the crystallite size is 50 nm or less.

The nonwoven fabric of the present invention has a desired fineness by pulling with a strong pulling force under the conditions that the fiber temperature at the inlet of the pulling device is set to be 30° C. or higher and the wind speed of the pulling air is set to be 5000 m/min or higher. crystal size. The fiber temperature is preferably 30°C to 80°C, more preferably 35°C to 70°C. The wind speed of the draft air is preferably not less than 6000 m/min and not more than 30000 m/min, more preferably not less than 7000 m/min and not more than 20000 m/min. By setting the fiber temperature at the inlet of the drawing device and the wind speed of the drawing air within these ranges, a predetermined crystallite size can be obtained, and the workability of the hygienic material is improved.

In addition, the drawing method of the nonwoven fabric of the present invention is not particularly limited. In order to obtain a nonwoven fabric with a large crystallite size and excellent thermal stability, it is better to use a high-speed airflow drawing device based on air jets. The traction device is better.

The average "bending softness" of the nonwoven fabric of the present invention defined below in the longitudinal and transverse directions is not less than 5 mm and not more than 100 mm, preferably not less than 5 mm and not more than 90 mm, more preferably not less than 10 mm and not more than 80 mm. When the flexural softness is within this range, it becomes a nonwoven fabric having excellent processability, texture, and flexibility.

Regarding the boiling water shrinkage of the nonwoven fabric of the present invention, since hot water surrounds the fiber, thermal energy can be efficiently transmitted, and it is an appropriate method for observing the thermal stability of the fiber. The shrinkage in boiling water in the present invention is preferably 0% to 3.0%, more preferably 0.1% to 2.0%, and still more preferably 0.1% to 1.0%. When the boiling water shrinkage ratio is within this range, shrinkage and wrinkles caused by heat during hot melt coating and heat sealing are suppressed in the production line of sanitary materials, and stable processing can be performed without breaking.

The dry heat shrinkage rate of the nonwoven fabric of the present invention is preferably 0% to 5.0% at 120°C, more preferably 0.1% to 3.0%, still more preferably 0.2% to 1.5%. When the dry heat shrinkage ratio is within this range, shrinkage and wrinkle generation due to heat during hot melt coating and heat sealing are suppressed in a hygienic material production line, and stable processing without breakage is possible.

Hydrophilic agents can also be used in the nonwoven fabric of the present invention. As the hydrophilic agent, in consideration of safety to the human body, safety in the process, etc., it is preferable to use one obtained by adding ethylene oxide to a higher alcohol, a higher fatty acid, an alkylphenol, etc. alone or in a mixture. Nonionic active agents, anionic active agents such as alkyl phosphates and alkyl sulfates, etc.

The amount of the hydrophilic agent attached varies depending on the desired performance, and is usually preferably in the range of 0.1% by weight to 1.0% by weight relative to the fiber, more preferably 0.15% by weight to 0.8% by weight, and still more preferably 0.2% by weight % or more and 0.6% by weight or less. When the adhesion amount is within this range, the hydrophilic performance of the top sheet as a hygienic material is satisfied, and the processability is also good.

As a method of applying a hydrophilic agent, generally, a diluted hydrophilic agent can be used, and an existing method such as a dipping method, a spray method, or a coating (roll coating, gravure coating) method can be used. The mixed hydrophilic agent is diluted with a solvent such as water, and then applied.

When the hydrophilizing agent is diluted with a solvent such as water and then applied, a drying step may be required. As the drying method at this time, known methods using convective heat transfer, conductive heat transfer, radiation heat transfer, etc. can be used, and hot air, drying using infrared rays, drying methods using thermal contact, etc. can be used.

Softeners can also be used in the nonwoven fabric of the present invention. As said softening agent, ester compounds are preferable, and ester compounds of 3-6 valent polyhydric alcohols and a monocarboxylic acid are mentioned more preferably.

Examples of 3- to 6-valent polyhydric alcohols include trivalent polyhydric alcohols such as glycerin and trimethylolpropane; Alcohol; triglycerin, trimethylolpropane diglycerol and other 5-membered polyols; sorbitol, tetraglycerin, dipentaerythritol and other 6-membered polyols, etc.

Examples of monocarboxylic acids include octanoic acid, dodecanoic acid, tetradecanoic acid, octadecanoic acid, behenic acid, hexacosanoic acid, octadecenoic acid, and docosenoic acid. , isosteardecanoic acid and other monocarboxylic acids; cyclohexane carboxylic acid and other alicyclic monocarboxylic acids; benzoic acid, methylbenzene carboxylic acid and other aromatic monocarboxylic acids; hydroxypropionic acid, hydroxyoctadecanoic acid, hydroxyl Hydroxy aliphatic monocarboxylic acids such as octadecenoic acid; sulfur-containing aliphatic monocarboxylic acids such as alkylthiopropionic acid, etc.

The ester compound does not have to be a single component, and may be a mixture of two or more types, or may be oils and fats derived from natural products. Among them, ester compounds containing unsaturated fatty acids are easily oxidized and are easily oxidized and deteriorated during spinning. Therefore, saturated aliphatic monocarboxylic acids or aromatic monocarboxylic acids are preferred. As oils and fats derived from natural products, hydrogenated ester compounds are preferably used because they are odorless and more stable than raw material oils.

As the ester compound, monocarboxylic acid preferably has a large molecular weight and high lipophilicity. Since the lipophilicity is high, the ester compound enters the amorphous part of the polyolefin fiber, hinders crystallization, increases the amorphous region, and thus reduces the flexural flexibility.

In order to obtain the above effect, the melting point of the ester compound is preferably 70°C or higher, more preferably 80°C or higher and 150°C or lower. When the melting point of an ester compound is broad and has a range, this melting point means an average melting point. In addition, other compositions such as ester compounds having a melting point of less than 70° C. and other organic compounds may be blended with the ester compound.

The content of the ester compound as a softener is preferably not less than 0.3% by weight and not more than 5.0% by weight relative to the polyolefin-based fibers. With regard to the ester compound, even if it is added in a small amount, the bending flexibility and the ease of sliding are significantly improved, and even if the content is increased, no performance improvement corresponding to the content is observed. Therefore, in consideration of spinnability and smoke generation, it is preferably 5.0% by weight or less, more preferably 0.5% by weight or more and 3.5% by weight or less, further preferably 0.5% by weight or more and 2.0% by weight or less.

The manufacturing method of the nonwoven fabric of the present invention is not particularly limited. Since it is mainly used for hygienic materials, the spunbond (S) method is preferred from the viewpoint of strength. By laminating into SS, SSS, and SSSS, the dispersion is improved, so it is more preferred. In addition, depending on the purpose, spunbond (S) fibers and meltblown (M) fibers may be laminated, and SM, SMS, SMMS, or SMSMS may be laminated.

The spinning temperature in the present invention is 190°C to 260°C, preferably 200°C to 255°C, more preferably 205°C to 230°C, further preferably 210°C to 225°C. When the spinning temperature is 260° C. or lower, the contamination of the spinneret surface by resin decomposition products is small, and the occurrence of thread breakage due to a decrease in the viscosity of the resin can be suppressed. In addition, when the spinning temperature is high, since the produced nonwoven fabric is affected by resin decomposition products, the bending softness is improved, and the nonwoven fabric tends to be hard as a nonwoven fabric. When the spinning temperature is 190° C. or higher, it is possible to suppress the occurrence of thread breakage due to an increase in the viscosity of the resin, and further suppress resin leakage due to an increase in the internal pressure of the spinneret during spinning.

The nonwoven fabric of the present invention may be long-fiber or short-fiber depending on the purpose, and is not particularly limited. Since it is mainly used for sanitary materials, long-fiber nonwoven fabric is preferable from the viewpoint of strength.

Since the nonwoven fabric of the present invention has very high thermal stability, it can be suitably used in the production of hygienic materials. Examples of hygienic materials include disposable diapers, sanitary napkins, and incontinence pads, and can be applied to top sheets on their surfaces. material, bottom sheet on the outside, side collectors around the bottom, etc.

In addition, the use of the nonwoven fabric of the present invention is not limited to the aforementioned uses, for example, it can also be used for facial masks, hand warmers, adhesive tape base cloths, waterproof sheet base cloths, external medicine base cloths, first aid bandage base cloths, packaging materials, Wipes, medical gowns, bandages, clothing, sheets for skin care, etc.

Example

Hereinafter, although an Example and a comparative example demonstrate this invention concretely, this invention is not limited only to a following example.

In addition, the evaluation methods of various characteristics used in the Example and the comparative example are as follows, and the obtained physical properties are shown in Table 1 below.

1. Average single yarn denier (dtex)

Remove 10 cm from both ends of the manufactured nonwoven fabric, divide it into about 5 equal parts in the width direction, take a 1 cm square test piece, measure the diameter of the fiber at 20 points each with a microscope, and calculate the fineness from the average value.

2. Weight per unit area (g/m ² )

According to JIS-L1906, 5 test pieces of 20 cm in length x 5 cm in width were selected arbitrarily, the mass was measured, and the average value thereof was converted into weight per unit area to obtain it.

3. Boiling water shrinkage (%)

Randomly select 3 test pieces with a length of 25 cm x a width of 25 cm, and mark marks that accurately represent the length of 20 cm in each of the vertical and horizontal positions of the sample.

After immersing the sample in boiling water for 3 minutes in a suitable container, take out the sample, gently absorb the water with filter paper, etc., clamp one end with a jig, hang it at room temperature, and make it dry. Next, the lengths of each of the longitudinal and transverse lengths of the first mark are measured at three places. The longitudinal contraction rate was calculated by the following formula, and the average value was calculated|required.

Boiling water shrinkage (%)=(L-L’)/L×100

{wherein, L: the sum of the lengths of the three lines before processing (mm), and L': the sum of the lengths of the three lines after processing (mm)}.

4. Dry heat shrinkage (%)

Randomly select 3 test pieces with a length of 25 cm x a width of 25 cm, and mark a mark that accurately represents the length of 20 cm on each of the vertical and horizontal positions of the sample.

Set the constant temperature dryer to 120°C, hang the sample in the dryer, and when the indicating scale of the dryer reaches the specified temperature, place it in the dryer for 3 minutes, take it out and cool it to room temperature. Next, the lengths of each of the longitudinal and transverse lengths of the first mark are measured at three places. The longitudinal contraction rate was calculated by the following formula, and the average value was calculated|required.

Dry heat shrinkage (%)=(L-L’)/L×100

{In the formula, L: the sum of the lengths of the three lines before processing (mm), and L': the sum of the lengths of the three lines after processing (mm)}.

5. Bending softness (mm)

Randomly select 5 test pieces with a width of 10 cm and a length of 30 cm from the non-woven fabric samples (select the sample with the measurement direction being 30 cm), and place them on a flat workbench as shown in Figure 1. A stainless steel ruler is placed in the center so as to be perpendicular to the longitudinal direction. The ruler preferably has a width of 2.5 cm and a measuring scale of 30 cm (1). Next, one end of the test piece was picked up, and the test piece on the opposite side was slowly overlapped with a stainless steel ruler as a boundary in a state where a loop was formed without creases (2). Next, slowly slide a stainless steel ruler in the direction of the folded ring in a state perpendicular to the longitudinal direction (3), and set the state where the fold disappears due to the stretching of the ring by the resilience of the sample as the end point, Read the distance (L) between the end of the test piece and the ruler with the scale (4). The flexural flexibility was calculated from the average value of n=5 measured values in the vertical and horizontal directions of the front and back. The smaller the value of the flexural softness (mm), the softer it is.

6. Crystallite size (nm)

Using an XRD analyzer [apparatus: NanoViewer manufactured by Rigaku Corporation, optical system: pinhole collimation (confocal mirror + first slit: 0.4 mmφ + second slit: 0.3 mmφ), X-ray source: CuKα ray, 45kV60mA, detector: imaging plate, camera length: 80.8mm], place a fiber in the sample cell, inject X-rays from the direction perpendicular to the fiber axis, and detect the transmitted scattered (diffracted) light. In order to reduce the influence of background scatter, all the downstream of the second slit is vacuum, and the X-ray path from the second slit to the detector is free of scatterers other than the sample.

With a measurement time of 10 to 12 hours, the one-dimensional WAXS curve is obtained from the two-dimensional pattern through the circular average, and the peaks are separated, and then the width of the diffraction peak originating from the (040) plane is calculated by the following formula. The crystallite size in the vertical direction.

[mathematical formula 1]

{In the formula, K: Scherrer constant (constant depending on the crystallite shape, etc.: use 0.9), λ: X-ray wavelength, β: peak width at half maximum (full width at half maximum: FWHM) (rad), and, b: Half width at half maximum (full width at half maximum: FWHM) (rad)} of divergence of the incident light beam.

7. Evaluation of wrinkle generation due to heat during processing (processability (processing suitability))

For a non-woven fabric sample with a width of 30 cm, a polyolefin-based hot-melt agent melted at 160° C. was applied to the non-woven fabric at a line speed of 50 m/min by a common hot-melt coating method known to those skilled in the art. on cloth. The wrinkle of the nonwoven fabric at the time of coating was evaluated according to the following evaluation criteria:

◎: no wrinkles

○: Wrinkles occur in the line direction, but coating is possible

×: Wrinkles are generated in the line direction and cannot be coated

[Example 1]

A polypropylene resin with an MFR of 60g/10min (measured according to JIS-K7210 at a temperature of 230°C and a load of 2.16kg) is spunbonded through a nozzle diameter of φ0.4mm and a single hole discharge amount of 0.56g/min·Hole , Extrude under the condition of spinning temperature of 215°C, use a high-speed airflow traction device based on air jets for the filament group, draw under the conditions that the fiber temperature at the entrance of the traction device is 40°C, and the traction air speed is 17500m/min , and extrude towards the moving collection surface to prepare a long-fiber web with an average single yarn denier of 1.1 dtex.

Then, make the obtained fiber web pass between the flat roller and the embossing roller (pattern specification: diameter 0.425mm circle, staggered arrangement, horizontal spacing 2.1mm, vertical spacing 1.1mm, crimping area ratio 6.3%), at temperature The fibers were bonded to each other at 135°C and a linear load of 35 kgf/cm to obtain a long-fiber nonwoven fabric with a weight per unit area of 17 g/m ² .

[Example 2]

The fiber temperature at the entrance of the traction device was set to 50°C, the draft air velocity was set to 15000m/min, and the same operation as in Example ¹ was performed to obtain a long-fiber nonwoven fabric with an average single yarn fineness of 1.5dtex and a weight per unit area of 11g/m2.

[Example 3]

The single-hole ejection amount is set to 0.90g/min·Hole, the fiber temperature at the entrance of the traction device is set to 65°C, and the draft air velocity is set to 12500m/min, and the same operation as in Example 1 is performed to obtain an average single yarn denier of 2.0dtex, Long-fiber non ^- woven fabric with a weight per unit area of 25g/m2.

[Example 4]

Polypropylene resin with an MFR of 60g/10min (measured according to JIS-K7210 at a temperature of 230°C and a load of 2.16kg) is spunbonded, with a nozzle diameter of φ0.48mm and a single-hole discharge rate of 0.33g/min· Hole, extruded at a spinning temperature of 230°C, the filament group is drawn by cold air pushing under the condition that the fiber temperature at the entrance of the pulling device is 40°C, and the wind speed of the pulling air is 6400m/min, and is collected towards the mobile Surface extrusion to prepare a long-fiber web with an average single yarn denier of 1.1 dtex.

Next, the fibers were bonded together in the same manner as in Example 1 to obtain a long-fiber nonwoven fabric with a basis weight of 17 g/m ² .

[Example 5]

The single-hole ejection amount is set to 0.66g/min·Hole, the fiber temperature at the entrance of the traction device is set to 60°C, and the draft air velocity is set to 5500m/min, and the same operation is performed as in Example 4 to obtain an average single yarn fineness of 2.2dtex, Long-fiber non ^- woven fabric with a unit area weight of 20g/m2.

[Example 6]

The fiber temperature at the entrance of the traction device was set to 50°C, the draft air velocity was set to 10000m/min, and the same operation as in Example ³ was performed to obtain a long-fiber nonwoven fabric with an average single yarn fineness of 2.8dtex and a weight per unit area of 18g/m2. The obtained non-woven fabric was passed through a corona discharge treater under the condition of a discharge capacity of 40 W·min/m ² (discharge degree 4.0 W/cm ² ) in an atmosphere at room temperature of 22° C. to obtain a wetting tension of 39 mN/m. non-woven fabric.

A polyether-based hydrophilic agent was applied to the obtained nonwoven fabric by a spray method, followed by hot air drying at 80° C. for 5 minutes to obtain a long-fiber nonwoven fabric having a hydrophilic agent concentration of 0.3% by weight.

[Example 7]

Set the fiber temperature at the entrance of the traction device to 50°C and the wind speed of the traction air to 12500m/min, and operate in the same manner as in Example 6 to obtain a fiber with an average single yarn fineness of 2.0dtex and a weight per unit area of 15g/m ² . Long-fiber nonwovens in an amount of 0.5% by weight.

[Example 8]

The fiber temperature at the entrance of the traction device was set to 60°C, the draft air velocity was set to 5000m/min, and the same operation was performed as in Example ⁵ to obtain a long-fiber nonwoven fabric with an average single yarn fineness of 2.6dtex and a weight per unit area of 17g/m2. The obtained non-woven fabric was passed through a corona discharge treater under the condition of a discharge capacity of 40 W·min/m ² (discharge degree 4.0 W/cm ² ) in an atmosphere at room temperature of 22° C. to obtain a wetting tension of 39 mN/m. non-woven fabric. A polyether-based hydrophilic agent was applied to the obtained nonwoven fabric by the lick roll coating method, followed by hot air drying at 80° C. for 5 minutes to obtain a long-fiber nonwoven fabric having a hydrophilic agent concentration of 0.3% by weight.

[Example 9]

Mix 1.25% by weight of stearic acid glyceride (hydrogenated animal and vegetable oil) with a melting point of 86-90°C (average melting point: 88°C), set the fiber temperature at the entrance of the traction device to 40°C, and the traction air velocity to 17500m /min, operate in the same way as in Example 1, obtain the long-fiber nonwoven fabric of average single yarn denier 1.1dtex, weight per unit area 17g/m ² .

[Example 10]

Mix 3.50% by weight of glycerides of octadecanoic acid (hydrogenated animal and vegetable oils and fats), set the fiber temperature at the entrance of the traction device to 40°C, and set the traction air wind speed to 17500m/min, operate in the same manner as in Example 1, and prepare the average single A long fiber web with a yarn denier of 1.1 dtex.

Next, the obtained fiber web was passed between a flat roll and an embossed roll (pattern specification: diagonal broken point pattern, crimping area ratio 14%), and the fibers were bonded to each other at a temperature of 135°C and a linear load of 35kgf/cm , to obtain a long-fiber nonwoven fabric with a weight per unit area of 15 g/m ² .

[Comparative example 1]

The single-hole ejection amount is set to 0.22g/min·Hole, the fiber temperature at the entrance of the traction device is set to 40°C, and the draft air velocity is set to 5500m/min, and the same operation as in Example 1 is performed to obtain an average single yarn fineness of 1.1dtex, Long ^- fiber nonwoven fabric with a weight per unit area of 17g/m2.

[Comparative example 2]

The single-hole ejection amount is set to 0.4g/min·Hole, the fiber temperature at the entrance of the traction device is set to 40°C, and the draft air velocity is set to 4000m/min, and the same operation as in Example 1 is performed to obtain an average single yarn fineness of 2.0dtex, Long-fiber non ^- woven fabric with a unit area weight of 20g/m2.

[Comparative example 3]

The fiber temperature at the inlet of the drawing device was set at 40° C., the drawing air velocity was set at 17500 m/min, and the operation was the same as in Example 1 to obtain a long-fiber web with an average single yarn fineness of 1.1 dtex.

Make the obtained fiber web pass between the flat roller and the embossing roller (pattern specifications: woven eye pattern, horizontal spacing 2.0mm, vertical spacing 2.0mm, crimping area 14.4%), set the temperature to 148°C, linear load setting It was 50kgf/cm, and a long ^- fiber nonwoven fabric with a basis weight of 17g/m2 was obtained.

[Table 1]

Industrial availability

Since the nonwoven fabric of the present invention has high thermal stability, excellent flexibility, and good processability, it can be suitably used for top sheets, back sheets, side collection parts, and the like of hygienic materials.

Claims (7)

1. A long-fiber nonwoven fabric, characterized in that it is formed of polyolefin fibers, the crystallite size of the polyolefin fibers exceeds 20 nm and is 50 nm or less, and the bending softness of the nonwoven fabric is 5 mm or more And less than 100mm, The flexural softness is calculated as follows: 5 test pieces with a width of 10 cm and a length of 30 cm are arbitrarily selected from the non-woven fabric samples, wherein the samples are selected with a measurement direction of 30 cm and placed on a flat workbench. A stainless steel ruler is placed in the center of the test piece in a manner perpendicular to the longitudinal direction. The width of the ruler is 2.5 cm and the measurement scale is 30 cm; The ruler is gradually overlapped in a state where a loop is formed on the opposite side of the test piece without creases; then, the stainless steel ruler is gradually folded in the direction of the loop formed by folding, and in a state perpendicular to the length direction. Sliding; take the state when the fold disappears due to the stretching of the sample by the resilience of the ring as the end point, and read the distance L between the end of the test piece in the direction of the straightedge in the forward direction and the straightedge with the scale; The mean value of each measured value of n=5 was used to calculate the flexural flexibility. 2. The long-fiber nonwoven fabric according to claim 1, wherein the boiling water shrinkage of the nonwoven fabric is 0% or more and 3.0% or less. 3. The long-fiber nonwoven fabric according to claim 1 or 2, wherein the polyolefin-based fibers are polypropylene-based fibers. 4. The long-fiber nonwoven fabric according to claim 1 or 2, wherein the polyolefin-based fibers have an average single-yarn fineness of 0.5 dtex to 3.5 dtex. 5. The long-fiber nonwoven fabric according to claim 1 or 2, wherein the nonwoven fabric has a dry heat shrinkage rate of 0% to 5.0% at 120°C. A hygienic material formed using the long-fiber nonwoven fabric according to any one of claims 1 to 5. 7. The hygienic material according to claim 6, which is in the form of a disposable diaper, a sanitary napkin, or an incontinence pad.