JPH0446146B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to disposable sanitary materials, particularly sanitary materials such as disposable diapers, sanitary napkins, and postpartum napkins. More particularly, the present invention relates to a novel disposable sanitary material comprising a nonwoven fabric as a topsheet that is flexible and has an improved surface feel. [Prior Art and Problems to be Solved by the Invention] Conventional disposable sanitary materials, such as disposable diapers and sanitary napkins, have a structure in which the surface that contacts the skin is sandwiched between an absorbent material made of cotton-like pulp, absorbent paper, superabsorbent resin, etc. It has a structure in which a liquid-permeable sheet and a liquid-impermeable sheet are arranged on the back side, and the drained liquid passes through the liquid-permeable sheet (hereinafter referred to as the top sheet), is absorbed and retained by the absorbent body, and is then placed on the back side. The liquid-impermeable sheet prevents liquid from leaking outside. A nonwoven fabric is generally used for this top sheet. The nonwoven fabric used as such a top sheet is required to have various performances, but the most important ones are that it comes into direct contact with the skin, so it must have excellent texture (feel and softness), and it must be disposable and hygienic. Materials are required to have practically satisfactory strength and dimensional stability during manufacture and use. Various nonwoven fabrics have been researched to meet the above requirements and have been proposed. BACKGROUND ART A nonwoven fabric is known in which short hydrophobic fibers are made into a web using a card and the fibers are joined by partial thermocompression bonding. This nonwoven fabric can give a sense of thickness and softness by crimping the fibers used, but on the other hand, the strength of the nonwoven fabric is insufficient during use and during the manufacturing process, and to compensate for this, it is relatively large. It is used as a nonwoven fabric with a basis weight of, for example, 20 g/m ² to 35 g/m ² . Furthermore, a nonwoven fabric is known in which a staple of potentially crimped fibers, such as a bicomponent composite fiber, is formed into a web and then heat-treated in an oven to develop crimps and bond the fibers. This nonwoven fabric has more sufficient crimp than the nonwoven fabric made by partial thermocompression bonding using cards, so it has a better thickness and softness, but it still has the problem of insufficient strength in use and manufacturing. Therefore, in order to compensate for these problems, it is necessary to use a nonwoven fabric with a high basis weight. Therefore, although these short fiber nonwoven fabrics have almost satisfactory performance in terms of texture, it must be said that their practical properties during the production and use of disposable sanitary materials are unsatisfactory. On the other hand, long-fiber nonwoven fabrics made of hydrophobic fibers, such as polypropylene, produced by the spunbond method are widely used as surface sheets for sanitary materials. This nonwoven fabric is strong and difficult to break during use, and has excellent dimensional stability during the production of sanitary materials. Therefore, it has a relatively low basis weight, ^e.g.
It can be used in the form of a 25g/m ² nonwoven fabric. However, since the fiber arrangement in this nonwoven fabric is planar, the bulkiness is poor, and the feel and softness are insufficient. As described above, long-fiber nonwoven fabrics produced by the spunbond method are preferable from the viewpoint of practical properties, but they are unsatisfactory in terms of feel. A nonwoven fabric is formed by stacking smooth fibers in layers. For this reason, conventionally known long-fiber nonwoven fabrics have smooth surfaces but are inferior in bulk, give a hard feel, and have a strong slimy surface. In order to eliminate these drawbacks of long fiber nonwoven fabrics, it has been proposed to use filaments of fine denier. If a filament with a fine denier is used, it will give a soft feel, but on the other hand, the bulkiness will be inferior, and the new drawback will be that the surface will feel sticky and the slimy feeling will become stronger. Furthermore, the fiber density becomes high, resulting in a problem of reduced liquid permeability when used as a top sheet. Therefore, the present invention solves the problems of top sheets in conventionally known disposable sanitary materials, and
The purpose of the present invention is to provide a disposable sanitary material comprising a nonwoven fabric that fully satisfies practical properties such as strength, dimensions, and stability during manufacture and use, and has excellent texture. [Means for Solving the Problems] An object of the present invention is to provide a method that includes a top sheet that is permeable to liquid discharged from the human body, a liquid-impermeable back sheet, and an absorbent body located between the front and back sheets. In the disposable sanitary material, the top sheet has a irregular cross section with a tapered tip and is made of a continuous filament of non-crimped thermoplastic synthetic fibers, and the filaments in the web are embossed. This is achieved by a disposable sanitary material characterized in that it is a nonwoven fabric formed by mutually bonding by partial thermocompression bonding with a minimum interval of 0.3 mm or more and 5 mm or less. The present invention will now be described in detail with reference to the accompanying drawings, which illustrate an example of the disposable sanitary material and nonwoven fabric of the present invention. FIG. 3 shows a plan view of an example of a disposable diaper, which is a type of disposable sanitary material of the present invention, and
The cross-sectional view is shown in the figure. As shown in FIGS. 3 and 4, the disposable diaper 1 includes a top sheet (top sheet) 2 on the front side, a liquid-impermeable back sheet (back sheet) 4 on the back side, and a diaper disposed between the top sheet 2 and the back sheet 4. The disposable diaper 1 is made of an absorbent body 3, and has serrations 5 on both sides of the disposable diaper 1, and tape fasteners 6 on both upper sides. Top sheet 2 when using
The liquid discharged from the human body is absorbed and retained by the absorbent body 3 through the top sheet 2, and the liquid is prevented from leaking to the outside by the liquid-impermeable back sheet 4. . Since the structure of such a disposable diaper itself is well known, description of each component other than the topsheet 2 will be omitted below. The nonwoven fabric used in the disposable diaper of the present invention (hereinafter referred to as the nonwoven fabric of the present invention) has an irregularly shaped cross section with a tapered tip and a first
It is made using a web consisting of continuous filaments of uncrimped thermoplastic fibers, as shown in FIGS. As the crystalline thermoplastic fibers mentioned herein, polyolefin fibers such as polypropylene fibers, polyester fibers such as polyethylene terephthalate fibers, and polyamide fibers such as nylon 6 or nylon 66 can be used alone or in combination. Further, the fibers may be used as composite fibers. Note that it is more preferable to use hydrophobic polyolefin fibers. A web consisting of continuous filaments can be formed by either a spunbond method in which the web is formed into a web immediately after spinning, or a tow spreading method in which the tow is opened after spinning. The nonwoven fabric of the present invention has a smooth surface feel. In order to provide such a feeling, it is preferable that the surface of the nonwoven fabric is uneven, both as the nonwoven fabric itself and as the constituent filaments themselves. In order to satisfy these conditions, the nonwoven fabric of the present invention uses a filament having an irregular cross-sectional shape. The shape of the irregular cross-section of the fiber used in the present invention is such that its tip 7 is tapered and pointed, as illustrated in FIGS. 5a to 5f. The use of filaments with such irregular cross-sections helps to soften the resulting nonwoven fabric. In other words, a collection of filaments with a circular cross section has almost uniform bending stiffness over the entire circumference in a plane perpendicular to the axis, but in the case of filaments with such a shaped cross section, each filament has a In a plane perpendicular to the axis, the filament has a strong direction and a weak direction, and therefore, an assembly of filaments with such irregular cross-sections tends to be easily bent as a whole. Therefore, the nonwoven fabric of the present invention using filaments with irregular cross sections has flexibility. In the nonwoven fabric of the present invention, the constituent filaments are substantially interconnected. "Substantially bonded to each other" as used herein does not mean that all of the intersection points of the multiple filaments that make up the nonwoven fabric are bonded, but that some of the intersection points are bonded at a rate that depends on the manufacturing conditions. Indicates that the As the joining method, a method using an adhesive, a heat fusion method using a composite fiber having a heat fusion component, or a partial thermocompression bonding method using an embossed member can be used. However, it is particularly preferable to use a partial thermocompression bonding method in terms of safety in use and taking advantage of the texture of the fiber itself. If the above-mentioned partial thermocompression bonding method is carried out appropriately to give unevenness to the surface of the nonwoven fabric, the smooth feel of the surface can be improved, or in order to impart flexibility, partial thermocompression bonding can be done by arranging many parallel lines. Such continuous partial thermocompression bonding is not preferable, and discontinuous partial thermocompression bonding is preferably performed. The smooth feel of the surface of the nonwoven fabric of the present invention is basically as clear from the evaluation results (Table 2) of Example 1 and Comparative Example 1 (same conditions except for the cross-sectional shape), which will be described later. This is considered to be due to the fact that the tips of the fibers of the topsheet of the present invention have a tapered shape. The partial thermocompression bonding method will be described in detail below. Partial thermocompression bonding is carried out by pressing a engraved roll or flat plate against each other, but the roll method is preferred from a production standpoint. A combination in which one is an engraving roll and the other is a smooth metal roll, or a method in which both the upper and lower engraving rolls are spliced together is adopted. The degree of thermocompression bonding is determined by setting the temperature and contact pressure of the upper and lower rolls according to the required performance such as strength or fluffiness of the resulting nonwoven fabric, but the upper hand temperature depends on the melting point of the fibers used. It is preferable to set the following. In addition, the texture of the finished nonwoven fabric is greatly influenced by the embossed pattern of the sculpture, especially the thermocompression area ratio,
The important points are the engraving interval and engraving depth. FIG. 6 shows examples of emboss patterns preferably used to produce the nonwoven fabric of the present invention, and Table 1 shows the corresponding dimensions of each emboss pattern. In FIG. 11, t indicates the minimum interval between each embossing.

【table】

〔Example〕

The present invention will be explained in further detail with reference to Examples below. Prior to the description of Examples, the definitions and measurement methods of physical property values used in the present invention will be summarized below. ◎ Fabric weight: Expressed in weight (g) per 1 m ² of nonwoven fabric. ◎ Thickness of nonwoven fabric Using a compressive elasticity tester model E-2 manufactured by Nakayama Electric Sangyo Co., Ltd., the thickness T (μ) of the nonwoven fabric at a load of 10 g is measured under a measurement area of 4 cm ² . ◎ Tensile strength, elongation at break, and 5% modulus in the vertical direction Take a 3 cm sample of the nonwoven fabric in the vertical and horizontal directions, and pull it with a Tensilon manufactured by Toyo Baldwin Co., Ltd. at a grasping interval of 10 cm and a tension speed of 30 cm/min. The test was conducted, and the tensile strength (Kg/3cm width), elongation at break (%), and stress at 5% elongation in the vertical direction are expressed as vertical 5% modulus (Kg/3cm width). ◎ Flexibility The bending resistance of JIS L 1096 was measured using the E method (6, 19, 5 handle-o-meter method). ◎ Permeation rate (sec/5c.c.) & rewetting amount (g) As an absorber, in order to keep the characteristics of the absorber constant, specific filter paper (#939, 10 manufactured by Eaton Dikeman) was used as the absorber.
Place the measuring device (approximately 800 g, 10 cm square, with a 25 mm diameter hole in the center) at the bottom of the measuring device. Place a test cloth (10 cm square) on top of this absorbent material. First, drip 5 c.c. of artificial urine from the top 25 mm.
Artificial urine is made by adding a nonionic activator to physiological saline25
45±3dyne/cm at °C (equivalent to infant urine)
Adjusted to. The dropping rate was 3.5 sec/25 c.c., which was defined as the permeation rate (sec/5 c.c.). Next, artificial urine is added as is, so that the total liquid volume is four times the absorbent weight so that the liquid volume contained in the absorbent body is constant. From above the test cloth
Apply a load of 800g/10cm square for 3 minutes to stabilize the distribution of liquid in the absorber. Next, a pre-weighed amount of filter paper (Eaton Dikeman #631,
12.5cm square
Corner load (equivalent to the load applied to an infant's diaper)
was applied for 2 minutes, and the weight increase of the filter paper was measured and determined as the rewetting amount (g). ◎ Surface feel (handling) The feel of the surface of the nonwoven fabric was evaluated by lightly touching the surface of the nonwoven fabric. ◎ Fabric width change due to vertical tension As a guide to know the fabric width change due to the tension applied to the nonwoven fabric in the actual process, take a sample of the nonwoven fabric with a width of 300 mm in the width direction (corresponding to the fabric width used in disposable diapers), and set the grasping interval to 2 m. Secure both ends.
Mark the center (1m section) and mark 2.1 on one end.
Increase the load to Kg, 3.8Kg, and 5.7Kg, and calculate the change in cloth width at the center mark part 10 seconds after applying each load to the original width (300mm) (%)
And so. Example 1 Polypropylene (MFR=
38JIS K7210 (measured under condition 4 in the table) at extrusion temperature
Quantitatively extruded at 1300g/min at 240℃, longitudinal direction with a 1540-hole triangular cross-section irregular nozzle (220 rows in the longitudinal direction and 7 rows in the width direction, equally spaced)
By using a short spinneret with a width of 1 m and 5 cm,
A group of irregularly shaped filaments is spun, pulled at a speed of 3500 m/min using a short high-speed air traction device, charged with a charging device at the bottom, and then moved onto a wire mesh web conveyor with a suction device. I made a receiving web. The cross-sectional shape of this irregularly shaped filament was as shown in FIG. 5a, and the single filament denier was 2.2 denier. This web is cut into the transverse line pattern shown in Figure 6 1 (2.6 mm width x 0.4 mm width, minimum interval 1.2 mm, thermocompression bonding area ratio 11.4%, depth 0.6 m/
A spunbond nonwoven fabric with a basis weight of 20 g/m ² (Figure 2) was obtained by partially thermo-pressing the upper and lower rolls at 135° C. and a pressure of 60 kg/cm using a thermo-compression roll that was a combination of the engraved roll and smooth metal roll (m). To this nonwoven fabric, 0.5% of a nonionic liquid permeable agent (nonylphenol ethylene oxide (8 to 10 mol) adduct 9) was added as a treatment agent. Table 2 shows the physical properties of the obtained nonwoven fabric. When this nonwoven fabric was used as a top sheet of a disposable diaper, the surface had a smooth and soft texture. Comparative Example 1 Same conditions as in Example 1 except that a rectangular spinneret with a circular cross section was used as the spinning nozzle.
A conventional spunbond nonwoven fabric of 20 g/m ² was obtained. Table 2 shows the physical properties of the obtained nonwoven fabric. Comparative Example 2 Comparative Example 2 was prepared using a commercially available nonwoven fabric (manufactured by Kendall Co., Ltd., USA), 24 g/m ² , which was partially thermocompressed after curling 2.3 d polypropylene short fibers, and Example 1.
compared with non-woven fabric. (See Table 2) Although the fiber cross section of this nonwoven fabric was circular, mechanical crimp due to carding was observed in each fiber. The partial thermocompression bonding had a small silk pattern (staggered arrangement).

【table】

[Table] Example 2 In Example 1, the thermoplastic resin was polyethylene terephthalate [η _sp/c = 0.70, (measured at 25°C using orthochlorophenol as a solvent)], and the extrusion temperature was 285°C, and the amount was determined at 1300 g/min. It was pushed out. The irregularly shaped filament was pulled at a speed of 4500 m/min to create a web. The upper and lower rolls were set to 35°C at 235°C using a thermocompression roll combined with the same engraving roll as in Example 1.
A spunbond nonwoven fabric with a basis weight of 15 g/m ² was obtained by partially thermocompression bonding at a pressure of Kg/cm. This nonwoven fabric was added with 0.2% of a nonionic liquid permeable agent (monolaurate ethylene oxide adduct) to form a surface sheet for sanitary materials. Compared to a spinning nozzle with a circular spinning nozzle under similar conditions, the strength was almost the same, but the surface texture was smooth and supple. Since this topsheet was made of polyester fibers, it had much better dimensional stability than nonwoven fabrics made of polyolefin fibers. Example 3 A spunbond nonwoven fabric for sanitary materials was obtained under the same conditions as in Example 1, except that the spinning nozzle was changed to a V-shaped cross-section irregular nozzle and a rectangular irregular nozzle. The performance was almost the same as that of Example 1, and it was strong and good, and had a smoother feel and supple softness compared to the conventional fibers using circular cross-sectional shapes. . Table 3 shows the physical properties of the obtained nonwoven fabric.

【table】

〔Effect of the invention〕

Since the disposable sanitary material according to the present invention is constructed as described above, it has excellent dimensional stability during the manufacture of sanitary materials such as disposable diapers and sanitary napkins, and is compatible with high-speed production machines, and has sufficient dimensional stability during use. It has practical properties and has a non-slimy feel and a soft texture, making it useful as an unprecedented and superior disposable sanitary material.

[Brief explanation of the drawing]

FIGS. 1 and 2 each show an example of a nonwoven fabric (hereinafter referred to as the nonwoven fabric of the present invention) used as the top sheet of the disposable diaper of the present invention, and are micrographs showing the shape of fibers in a cross section of the nonwoven fabric. The figure is a plan view showing an example of the structure of a disposable diaper, FIG. 4 is a sectional view of the disposable diaper shown in FIG. 3, and FIG. FIG. 6 is a diagram showing the embossed pattern used in manufacturing the nonwoven fabric of the present invention across FIGS. 6 1 to 6, and FIG. It is a graph showing (width filling rate). 1...Disposable diaper, 2...Top sheet, 3
...Absorbent body, 4...Liquid-impermeable back sheet, 5...
...Guzzle, 6...Tape fastener, 7...Protrusion in the filament cross section.

Claims (1)

[Claims] 1. A disposable sanitary material comprising a top sheet that can transmit liquid discharged from the human body, a liquid-impermeable back sheet, and an absorbent body located between the front and back sheets, wherein the top sheet has a tapered tip. Using a web made of continuous filaments of non-crimped thermoplastic synthetic fibers and having an irregularly shaped cross section with a sharp point, the constituent filaments in the web are partially thermocompressed with a minimum embossing interval of 0.3 mm or more and 5 mm or less. A disposable sanitary material characterized by being a nonwoven fabric made of