Nonwoven fabric and products made therefrom

Abstract

To provide a nonwoven fabric that offers excellent flexibility while suppressing strength reduction and fluffing.SOLUTION: There is provided a nonwoven fabric comprising a thermally bondable composite fiber constituted by a high-melting-point component mainly composed of a polyester-based resin and a low-melting-point component mainly composed of a thermoplastic resin having a lower melting point than the polyester-based resin, wherein intersections of the thermally bondable composite fibers are thermally bonded throughout the entire nonwoven fabric, and the drape coefficient is 0.1 to 0.5.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a nonwoven fabric having excellent softness and strength, and to a product obtained using the same. [Background technology]

[0002] Nonwoven fabrics used in disposable diapers, sanitary napkins, sanitary masks, and other products require comfortable wear, so materials with good texture, including cushioning and flexibility (drapeability), are preferred. A widely used material with good cushioning properties is nonwoven fabric (through-air nonwoven fabric) made by thermally bonding a web of thermally bondable fibers using a circulating hot air heat treatment machine. This type of nonwoven fabric is preferred for its bulky, cushioning properties. However, because the fiber intersections of through-air nonwoven fabrics are thermally bonded throughout the entire fabric, they tend to develop irregular peaks when bent, resulting in poor flexibility and creating gaps between the fabric and the skin, which can lead to problems such as urinary leakage. Therefore, a through-air nonwoven fabric that combines both cushioning and flexibility is needed.

[0003] On the other hand, a method for producing a nonwoven fabric with excellent flexibility is known in which a fiber web is sandwiched between embossing rolls or the like and partially bonded by flattening (for example, Patent Document 1). Because this type of nonwoven fabric is produced by partially flattening the fiber web, it tends to bend at the boundaries between the bonded and non-bonded portions, resulting in a nonwoven fabric with a certain degree of flexibility. However, the flattened portions are molten and film-like, making them hard and uncomfortably soft to the touch. Another method is known in which a fiber web is entangled mechanically or by water flow (for example, Patent Document 2). Because the fibers are entangled, this type of nonwoven fabric has excellent flexibility, but because the fiber intersections are not bonded, it has problems such as reduced strength, reduced cushioning, and a tendency to pill.

[0004] Also known is a nonwoven fabric in which a fiber web is covered with punching plates and thermally bonded in a circulating hot air heat treatment machine while being transported on a conveyor net (for example, Patent Document 3). Such a nonwoven fabric has high bulk and excellent flexibility because the bonded fiber portions are not flattened by pressure bonding. However, there are areas where the fibers are not bonded, which causes problems such as reduced strength and increased fuzzing. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-30524 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-190065 [Patent Document 3] Japanese Patent Application Laid-Open No. 2001-3253 Summary of the Invention [Problem to be solved by the invention]

[0006] As described above, although there have been attempts to improve the softness of nonwoven fabrics, the current situation is that all of these attempts have resulted in nonwoven fabrics that are prone to loss of strength and fuzzing. In view of this situation, an object of the present invention is to provide a nonwoven fabric that has excellent softness while suppressing loss of strength and fuzzing. [Means for solving the problem]

[0007] The inventors have conducted extensive research to solve the above-mentioned problems, and as a result have found that the above-mentioned problems can be solved by consolidating a nonwoven fabric containing specific thermally bondable conjugate fibers and having fiber intersections thermally bonded throughout the entire nonwoven fabric under specific conditions, which led to the completion of the present invention.

[0008] That is, the present invention has the following configuration. [1] A nonwoven fabric containing thermally adhesive conjugate fibers composed of a high-melting point component mainly composed of a polyester-based resin and a low-melting point component mainly composed of a thermoplastic resin having a melting point lower than that of the polyester-based resin, wherein the intersections of the thermally adhesive conjugate fibers are thermally bonded throughout the entire nonwoven fabric, and the nonwoven fabric has a drape coefficient of 0.1 to 0.5. [2] The nonwoven fabric according to [1], which has a thickness change rate of 50% or less when heat-treated at 100°C for 5 minutes. [3] The nonwoven fabric according to [1] or [2], wherein the thermoplastic resin of the low-melting point component is a polyolefin resin. [4] A method for producing a nonwoven fabric, comprising the steps of: forming a web containing thermally adhesive conjugate fibers composed of a high-melting point component mainly composed of a polyester-based resin and a low-melting point component mainly composed of a thermoplastic resin having a melting point lower than that of the polyester-based resin; thermally bonding intersections of the thermally adhesive conjugate fibers throughout the entire web; and, after the thermal bonding step, performing a consolidation treatment in a temperature range of +10°C or more above the glass transition temperature of the polyester-based resin and -10°C or less below the melting point of the thermoplastic resin of the low-melting point component. [5] An absorbent article using the nonwoven fabric according to any one of [1] to [3]. [6] A sanitary material using the nonwoven fabric described in any one of [1] to [3]. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a nonwoven fabric that has excellent flexibility while suppressing a decrease in strength and fluffing. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram of photographing in the procedure (3) for measuring the drape coefficient in the examples and comparative examples. [Figure 2] 1 is a photograph of the entire nonwoven fabric sample with a circular plate placed thereon, taken in step (3) during measurement of the drape coefficient in Example 3 of the present invention. [Figure 3] 1 is a photograph of the entire nonwoven fabric sample with a circular plate placed thereon, taken in step (3) during measurement of the drape coefficient in Comparative Example 2 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to the following embodiments.

[0012] The nonwoven fabric of the present invention comprises thermally adhesive conjugate fibers composed of a high-melting point component mainly composed of a polyester-based resin and a thermoplastic resin having a melting point lower than that of the polyester-based resin, wherein the intersections of the thermally adhesive conjugate fibers are thermally bonded throughout the entire nonwoven fabric, and the nonwoven fabric has a drape coefficient of 0.1 to 0.5.

[0013] The thermally bondable conjugate fiber used in the nonwoven fabric of the present invention is composed of a high-melting-point component primarily composed of a polyester resin and a low-melting-point component primarily composed of a thermoplastic resin with a melting point lower than that of the polyester resin. The inclusion of such thermally bondable conjugate fibers improves the flexibility of the nonwoven fabric. Without being bound by any particular theory, it is believed that the polyester resin in the thermally bondable conjugate fiber has an appropriate degree of crystallinity and orientation, without being overly structurally developed due to the stress and thermal history of the fiber manufacturing process. Therefore, it is believed that consolidation treatment after nonwoven fabric formation (after bonding points are formed at the intersections of the thermally bondable conjugate fibers using the low-melting-point component) relaxes the molecular orientation of the amorphous portion of the polyester resin due to the consolidation stress, making it less likely to develop sharp corners when bent, thereby improving the flexibility of the nonwoven fabric. Furthermore, it is believed that the low-melting-point component maintains the bonding at the intersections of the thermally bondable conjugate fibers during consolidation, thereby suppressing strength loss and fuzzing.

[0014] <High melting point component> The high-melting point component in the thermal adhesive conjugate fiber used in the nonwoven fabric of the present invention is mainly composed of a polyester resin, and the proportion of the polyester resin in the total amount of the high-melting point component is preferably 80% by weight or more, more preferably 90% by weight or more.

[0015] The polyester resin is not particularly limited, and examples thereof include aromatic polyamide resins such as polyethylene terephthalate (PET), polybutylene terephthalate, polytrimethylene terephthalate, and polybutylene naphthalate, and aliphatic polyester resins such as polylactic acid, polyglycolic acid, and polybutylene succinate, but considering the raw material cost and the strength of the nonwoven fabric, the polyester resin is preferably polyethylene terephthalate. Furthermore, these polyester resins may be not only homopolymers but also copolymer polyesters such as copolymer polyethylene terephthalate (coPET), and two or more of these polyester resins may be mixed.

[0016] The high-melting point component may contain inorganic fine particles as needed to improve the flexibility of the nonwoven fabric. The amount of inorganic fine particles added is preferably 0 to 10% by mass, more preferably 0.1 to 10% by mass, and even more preferably 1 to 5% by mass, based on the fiber.

[0017] The inorganic fine particles are not particularly limited as long as they have a high specific gravity and are unlikely to aggregate in the molten resin. Examples include titanium oxide (specific gravity 3.7-4.3), zinc oxide (specific gravity 5.2-5.7), barium titanate (specific gravity 5.5-5.6), barium carbonate (specific gravity 4.3-4.4), barium sulfate (specific gravity 4.2-4.6), zirconium oxide (specific gravity 5.5), zirconium silicate (specific gravity 4.7), alumina (specific gravity 3.7-3.9), magnesium oxide (specific gravity 3.2), or substances with approximately the same specific gravity, with titanium oxide being preferred. These inorganic fine particles are generally known to be added to fibers for purposes such as hiding, antibacterial, or deodorizing properties. The inorganic fine particles used preferably have a particle size and shape that do not cause problems such as thread breakage during the spinning or drawing process.

[0018] <Low melting point component> The low-melting point component in the thermal adhesive conjugate fiber used in the nonwoven fabric of the present invention is primarily composed of a thermoplastic resin having a melting point lower than that of the polyester resin that is the primary component of the high-melting point component. Here, "primary component" refers to the component that accounts for the largest proportion of the components that make up the low-melting point component, and the thermoplastic resin with a low melting point preferably accounts for 80% by weight or more, and more preferably 90% by weight or more, of the polyester resin that is the primary component of the high-melting point component. The thermoplastic resin is not particularly limited as long as it has a melting point lower than that of the polyester resin that is the main component of the high-melting point component, and examples include high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), polypropylene (PP), propylene-based copolymer (coPP), ethylene-vinyl alcohol copolymer, ethylene-vinyl acetate copolymer, nylon 6, polylactic acid, copolymerized polyethylene terephthalate, polyurethane, and fluororesin. However, taking into consideration raw material costs and the flexibility of the nonwoven fabric, polyolefin-based resins such as high-density polyethylene, low-density polyethylene, linear low-density polyethylene, polypropylene, and propylene-based copolymers are preferred, and high-density polyethylene is more preferred.

[0019] From the viewpoint of expanding the processing temperature range of the nonwoven fabric, the melting point of the thermoplastic resin that is the main component of the low-melting point component is preferably at least 10°C lower, and more preferably at least 20°C lower, than the melting point of the polyester resin that is the main component of the high-melting point component.

[0020] The low-melting point component and the high-melting point component may contain additives such as antioxidants, light stabilizers, ultraviolet absorbers, neutralizing agents, nucleating agents, epoxy stabilizers, lubricants, antibacterial agents, deodorizing agents, flame retardants, antistatic agents, pigments, or plasticizers, as needed, within the range that does not impair the effects of the present invention.

[0021] <Thermal adhesive composite fiber> The thermal adhesive conjugate fiber contained in the nonwoven fabric of the present invention is not particularly limited as long as it satisfies the condition that it is composed of a high-melting point component mainly composed of a polyester-based resin and a low-melting point component mainly composed of a thermoplastic resin having a melting point lower than that of the polyester-based resin, and can be selected from the above-mentioned high-melting point component and low-melting point component.

[0022] Specific examples of combinations of polyester resin, which is the main component of the high-melting point component, and thermoplastic resin, which is the main component of the low-melting point component, include PET / HDPE, PET / LLDPE, PET / Co-PET, PET / PP, polylactic acid / HDPE, polylactic acid / polybutylene succinate, and PET / polylactic acid. From the standpoints of flexibility of the nonwoven fabric, raw material costs, production stability, and the like, the combinations of PET / HDPE, PET / LLDPE, PET / PP, polylactic acid / HDPE, and polylactic acid / polybutylene succinate are preferred, and the combination of PET / HDPE is more preferred.

[0023] The cross-sectional shape of the thermally bondable conjugate fiber is not particularly limited as long as it can be melted by heat to form bonding points, and examples thereof include concentric sheath-core type thermally bondable conjugate fibers, eccentric sheath-core type thermally bondable conjugate fibers, side-by-side type thermally bondable conjugate fibers, splittable type thermally bondable conjugate fibers, and islands-in-the-sea type thermally bondable conjugate fibers. The cross-sectional shape of the thermally bondable conjugate fiber is also not particularly limited, and any of round shapes such as circles and ellipses, angular shapes such as triangles and squares, irregular shapes such as stars and octave shapes, and split or hollow shapes can be used.

[0024] The volume ratio of the high-melting point component to the low-melting point component is not particularly limited, but is preferably 20 / 80 to 80 / 20, and more preferably 30 / 70 to 70 / 30. If the low-melting point component is 20% by volume or more, the bonded joint strength of the thermally adhesive conjugate fiber is improved and a high-strength nonwoven fabric is obtained, while if it is 80% by volume or less, the flexibility of the nonwoven fabric tends to be improved. Furthermore, from the viewpoint of thermal adhesiveness, the low-melting point component preferably accounts for 50% or more, and more preferably 70% or more, of the surface of the thermally adhesive conjugate fiber.

[0025] The fineness of the thermal adhesive conjugate fiber is not particularly limited, but the smaller the fineness of the thermal adhesive conjugate fiber, the easier it is to obtain a nonwoven fabric with excellent flexibility, but by increasing the fineness to a certain extent, it becomes easier to form a web. From this viewpoint, the fineness of the thermal adhesive conjugate fiber is preferably 0.8 to 20 dtex, more preferably 0.9 to 10 dtex, and even more preferably 1 to 6 dtex.

[0026] The thermal adhesive conjugate fiber may be a long fiber or a short fiber, but is preferably a short fiber from the viewpoint of improving processability and flexibility, and the fiber length is preferably 20 to 102 mm, more preferably 30 to 51 mm. In a web formation step by a carding method or the like, a web with excellent openability and texture can be easily formed, and a nonwoven fabric with uniform physical properties can be obtained, so the fiber length is preferably 20 to 102 mm.

[0027] In addition to the thermally bondable composite fibers described above, the nonwoven fabric of the present invention may contain fibers other than thermally bondable composite fibers (hereinafter referred to as "non-thermobondable fibers"), such as natural fibers (e.g., wood fibers), recycled fibers (e.g., rayon), semi-synthetic fibers (e.g., acetate), chemical fibers, and synthetic fibers (e.g., polyester, acrylic, nylon, vinyl chloride). "Non-thermobondable fibers" refer to fibers that do not undergo thermal changes (melting or softening) that contribute to thermal bonding during the thermal bonding process carried out in the production of the nonwoven fabric. The inclusion of non-thermobondable fibers can further improve the flexibility of the nonwoven fabric. When non-thermobondable fibers are included, the proportion of the non-thermobondable fibers relative to the total weight of the nonwoven fabric is not limited as long as it does not impair the effects of the present invention, but can be, for example, 1 to 30 wt %, preferably 3 to 15 wt %. A proportion of non-thermobondable fibers of 1 wt % or more improves the flexibility of the nonwoven fabric, while a proportion of non-thermobondable fibers of 30 wt % or less can suppress a decrease in strength and fluffing. Furthermore, the surfaces of the thermally bondable conjugate fibers and non-thermally bondable fibers may be treated with various fiber treatment agents, thereby imparting functions such as hydrophilicity, durable hydrophilicity, water repellency, antistatic properties, surface smoothness, and abrasion resistance.

[0028] <Nonwoven fabric> The nonwoven fabric of the present invention is characterized in that the intersections of the above-mentioned thermally adhesive conjugate fibers are thermally bonded over the entire surface of the nonwoven fabric, and has a drape coefficient of 0.1 to 0.5.

[0029] Here, a state in which the intersections of the thermally bondable conjugate fibers are thermally bonded over the entire nonwoven fabric means that the intersections of the thermally bondable conjugate fibers are not separated into thermally bonded areas and other areas, and refers to a state in which bonded points are formed at approximately the same rate in the surface direction and thickness direction of the nonwoven fabric.

[0030] The drape coefficient of the nonwoven fabric of the present invention is 0.1 to 0.5, preferably 0.2 to 0.5, and more preferably 0.25 to 0.45. The drape coefficient is a representative index showing the softness of a nonwoven fabric, and the smaller the drape coefficient, the higher the softness. For excellent softness of the nonwoven fabric, the drape coefficient is preferably less than 0.5. Furthermore, taking into consideration the strength of the nonwoven fabric, the drape coefficient is preferably greater than 0.1.

[0031] The thickness change rate of the nonwoven fabric of the present invention when heat-treated at 100°C for 5 minutes is not particularly limited, but is preferably 50% or less, more preferably 40% or less, and even more preferably 30% or less. A smaller thickness change rate indicates better dimensional stability, and a nonwoven fabric with a small thickness change rate, i.e., one that does not rebulk, lacks three-dimensionality in the thickness direction and is more flexible. Because the thermally adhesive composite fiber described above is primarily composed of a polyester resin as a high-melting-point component, thickness change due to thermal shrinkage of the fiber is likely to occur. However, the nonwoven fabric of the present invention has the secondary effect of being less susceptible to such thickness change.

[0032] The nonwoven fabric of the present invention may be made of one type of (single-layer) nonwoven fabric, or may be made by laminating two or more types of nonwoven fabrics differing in fineness, composition, density, or the like.

[0033] The nonwoven fabric may be subjected to antistatic treatment, water-repellent treatment, hydrophilic treatment, antibacterial treatment, ultraviolet absorbing treatment, near-infrared absorbing treatment, electret treatment, or the like depending on the purpose, as long as the effects of the present invention are not impaired.

[0034] <Nonwoven fabric manufacturing method> The method for producing a nonwoven fabric of the present invention includes the steps of forming a web containing the above-mentioned thermally adhesive conjugate fibers (hereinafter sometimes referred to as the web formation step), thermally bonding the intersections of the thermally adhesive conjugate fibers throughout the entire web (hereinafter sometimes referred to as the thermal bonding step), and, after the thermal bonding step, performing a consolidation treatment at a temperature range of +10°C or more above the glass transition temperature of the polyester resin and -10°C or less below the melting point of the thermoplastic resin of the low-melting point component (hereinafter sometimes referred to as the consolidation step). This method makes it possible to produce a nonwoven fabric that has excellent flexibility while suppressing a decrease in strength and fluffing.

[0035] <Web forming process> The process for forming the web is not particularly limited, but includes the spunbond method, meltblowing method, airlaid method, carding method, and the like.

[0036] <Thermal bonding process> The intersections of the thermally bondable conjugate fibers are thermally bonded throughout the entire web obtained in the web-forming process. Any method capable of thermally bonding the intersections of the thermally bondable conjugate fibers throughout the entire web may be used, such as a method in which the web is continuously thermally bonded by introducing the web into a furnace filled with circulating hot air or superheated steam gas using a transport conveyor or the like. The temperature of the circulating hot air or superheated steam gas is not particularly limited as long as it is within a range in which the intersections of the thermally bondable conjugate fibers can be satisfactorily bonded, but an example is a temperature of 0 to 30°C above the melting point or softening point of the thermoplastic resin that is the main component of the low-melting-point component. The blowing speed of the circulating hot air or superheated steam gas is also not particularly limited, and an example is 0.1 to 10 m / min.

[0037] <Consolidation process> Next, the nonwoven fabric obtained in the thermal bonding step is subjected to a consolidation treatment at a temperature range of at least +10°C above the glass transition temperature of the polyester-based resin, which is the main component of the high-melting-point component, and at most -10°C below the melting point of the thermoplastic resin, which is the main component of the low-melting-point component. By consolidating within this temperature range, the molecular orientation of the polyester-based resin is relaxed and excessive bonding of the low-melting-point component is suppressed, resulting in a nonwoven fabric with excellent flexibility. From this perspective, the lower limit temperature of the consolidation step is preferably at least +15°C above the glass transition temperature of the polyester-based resin, which is the main component of the high-melting-point component, and more preferably at least +20°C above the glass transition temperature of the polyester-based resin, which is the main component of the high-melting-point component. Furthermore, the upper limit temperature of the consolidation step is preferably at most -15°C below the melting point of the thermoplastic resin, which is the main component of the low-melting-point component, and more preferably at most -20°C below the melting point of the thermoplastic resin, which is the main component of the low-melting-point component. For example, if the high-melting-point component is polyethylene terephthalate with a glass transition temperature of 70°C and a melting point of 255°C, and the low-melting-point component is high-density polyethylene with a melting point of 130°C, the temperature in the consolidation step is 80 to 120°C, preferably 85 to 115°C, and more preferably 90 to 110°C. The pressure (surface pressure) and time in the consolidation step can be appropriately set while considering the balance between the flexibility and strength of the resulting nonwoven fabric. The conditions are adjusted so that the thickness change rate of the sample is 50% or less when the resulting nonwoven fabric is heat-treated in a 110°C oven for 5 minutes. The consolidation step is not particularly limited, and examples include methods of consolidating the nonwoven fabric by calendaring or pressing.

[0038] The nonwoven fabric of the present invention can be used for a variety of textile products that require excellent flexibility and suppression of strength loss and fluffing, such as absorbent articles such as diapers, napkins, and incontinence pads; sanitary materials such as sanitary masks, gowns, and surgical gowns; interior materials such as wall sheets, shoji paper, and flooring; daily life materials such as cover cloths, cleaning wipers, and food waste covers; toiletry products such as disposable toilets and toilet covers; pet supplies such as pet sheets, pet diapers, and pet towels; industrial materials such as wiping materials, filters, cushioning materials, oil adsorbents, and adsorbents for ink tanks; general medical materials, bedding materials, and nursing care products. [Example]

[0039] The present invention will be described in detail below with reference to examples, but the present invention is not limited thereto. The measurement methods or definitions of the physical properties shown in the examples are shown below.

[0040] <Fineness of thermally adhesive composite fiber> The fineness of the thermal adhesive composite fiber was measured in accordance with JIS L 1015.

[0041] <Nonwoven fabric basis weight> The weight of a nonwoven fabric cut into a 10cm x 10cm square was measured and converted to a unit area to determine the basis weight (g / m 2 ) was measured.

[0042] <Thickness of nonwoven fabric> A nonwoven fabric cut into a 10cm x 10cm square was subjected to a pressure of 3.5g / cm using a Toyo Seiki DigiSickness Tester with a 35mm diameter indenter (load). 2 The thickness (mm) was measured when a pressure of 1000 kJ / cm was applied.

[0043] <Specific volume of nonwoven fabric> The specific volume was calculated using the following formula: Specific volume (cm 3 / g) = Nonwoven fabric thickness (mm) / basis weight (g / m 2 ) x 1000

[0044] <Drape coefficient of nonwoven fabric> This is an in-house method based on JIS L1096 G method (drape coefficient method), and was carried out using the following procedure. (1) The nonwoven fabric is cut into a circle with a diameter of 250 mm to serve as a sample. (2) The center of the sample is sandwiched between two 120 mm diameter disks and placed on a cylindrical stand 107 mm in diameter and 150 mm in height. (3) The entire sample is photographed using a camera fixed 500 mm above the floor (350 mm above the sample). (4) Using the image processing software ImageJ, calculate the area (Ad) of the entire sample photographed by the camera. (5) Calculate the drape coefficient using Equation 1. Formula 1 Df = (Ad - S1) / (S2 - S1) Df: Drape coefficient Ad: Image analysis of the test piece. Area of ​​the nonwoven fabric (drape area) (mm 2 ) S1: Area of ​​the sample stage (mm 2 ) S2: Sample cutout area (mm 2 ) (6) The measurements (1) to (5) above were carried out three times, and the average value was used as the drape coefficient.

[0045] <Breaking strength of nonwoven fabric> A sample measuring 5 cm x 15 cm was cut out in the direction of flow and pulled using an Autograph (AGX-J) manufactured by Shimadzu Corporation at a chuck distance of 100 mm and a pulling speed of 100 mm / min. The maximum strength measured was taken as the strength of the nonwoven fabric (N / 5 cm).

[0046] <Thickness change rate of nonwoven fabric> The thickness of a nonwoven fabric sample cut to 25cm x 25cm after heat pressing was measured using a DigiSickness Tester manufactured by Toyo Seiki Seisakusho Co., Ltd., with a pressure of 3.5g / cm using a 35mm diameter indenter (load). 2 The thickness (mm) when pressure is applied is measured and taken as the A value. The nonwoven fabric was heat-treated in an oven at 100°C for 5 minutes, then removed from the oven and allowed to cool to room temperature. The thickness of the sample was measured in the same manner as above and recorded as the thickness of the nonwoven fabric after heat treatment (B). The thickness change rate (%) of the nonwoven fabric was calculated from the thickness (mm) of the nonwoven fabric after heat pressing (A) and the thickness (mm) of the nonwoven fabric after heat treatment (B) using the following formula: Nonwoven fabric thickness change rate (%) = (BA) / B × 100

[0047] <Fuzz resistance evaluation> Five panelists visually inspected the surface of the same nonwoven fabric sample from a horizontal direction, and if four or more panelists judged that there was no fuzz, the sample was rated as ◯; if three or two panelists judged that there was no fuzz, the sample was rated as △; and if four or more panelists judged that there was fuzz, the sample was rated as ×.

[0048] [Example 1] The core is made of polyethylene terephthalate (intrinsic viscosity (measured using an equal weight mixed solvent of phenol and tetrachloroethane, concentration 0.5 g / 100 ml, temperature 20°C): 0.64 dl / g, melting point: 255°C, glass transition temperature: 70°C), and the sheath is made of high-density polyethylene (density: 0.956 g / cm 3 The concentric sheath-core type thermal adhesive composite fiber (1) was used, which had a fineness of 1.7 dtex and a melt index (190°C, load 21.18N): 16.5 g / 10 min, melting point: 130°C) in a volume ratio of 50 / 50. The thermally bondable composite fibers (1) were formed into a web by a carding method, and circulating hot air at 130°C was passed uniformly through the entire web for 5 seconds to thermally bond the intersections of the thermally bondable composite fibers (1), and the web was then wound up.The wound up nonwoven fabric was then pressed in a heat press at a temperature of 90°C and a surface pressure of 400 gf / cm. 2 (0.039 MPa) for 5 min to obtain a nonwoven fabric. The basis weight of the obtained nonwoven fabric was 25.0 g / m 2 , thickness 0.13 mm, specific volume 5.2 cm 3 / g, drape coefficient was 0.42, breaking strength was 49.3 N / 5 cm, thickness change rate was 45.6%, and fluffing resistance was rated as good.

[0049] [Example 2] A nonwoven fabric was obtained in the same manner as in Example 1, except that the temperature in the consolidation step was changed to 100° C. The basis weight of the obtained nonwoven fabric was 25.0 g / m 2 , thickness 0.15 mm, specific volume 6.0 cm 3 / g, drape coefficient was 0.37, breaking strength was 49.3 N / 5 cm, thickness change rate was 30.1%, and fluffing resistance was rated as good.

[0050] [Example 3] A nonwoven fabric was obtained in the same manner as in Example 1, except that the temperature in the consolidation step was changed to 110° C. The basis weight of the obtained nonwoven fabric was 25.0 g / m 2 , thickness 0.10 mm, specific volume 5.6 cm 3 / g, drape coefficient was 0.33, breaking strength was 49.3 N / 5 cm, thickness change rate was 4.0%, and fluffing resistance was rated as good.

[0051] [Comparative Example 1] A nonwoven fabric was obtained in the same manner as in Example 1, except that no compaction processing was performed. The basis weight of the obtained nonwoven fabric was 25.0 g / m 2 , thickness is 0.86 mm, specific volume is 34.4 cm 3 / g, drape coefficient was 0.73, breaking strength was 49.3 N / 5 cm, thickness change rate was 100.0%, and fluffing resistance was rated as good.

[0052] Comparative Example 2 A nonwoven fabric was obtained in the same manner as in Example 1, except that the temperature in the consolidation step was changed to 70° C. The basis weight of the obtained nonwoven fabric was 25.0 g / m 2 , thickness is 0.47 mm, specific volume is 18.8 cm 3 / g, drape coefficient was 0.66, breaking strength was 49.3 N / 5 cm, thickness change rate was 78.4%, and fluffing resistance was rated as good.

[0053] Comparative Example 3 A web made of the thermal adhesive composite fiber (1) was formed by the carding method, and embossed at a linear pressure of 20 kg / cm using an embossing roll with an embossed area ratio of 25% heated to 132°C and a flat roll to obtain a nonwoven fabric. The weight of the obtained nonwoven fabric was 20.4 g / m 2 , thickness 0.25mm, specific volume 12.2cm 3 / g, drape coefficient was 0.51, breaking strength was 45.0 N / 5 cm, and fluffing resistance was good.

[0054] Comparative Example 4 A web of the thermally bondable composite fibers (1) was formed by a carding method using concentric sheath-core type thermally bondable composite fibers (1), and the web was covered with a punching board with circular holes 5 mm in diameter perforated in a staggered pattern at 10 mm intervals, and the intersections of the thermally bondable composite fibers (1) were thermally bonded using circulating hot air at 130°C to obtain a nonwoven fabric. The intersections of the fibers in the hole areas of the punching board were thermally bonded, but the intersections of the fibers in areas other than the holes were not thermally bonded. The weight of the obtained nonwoven fabric was 25.6 g / m 2 , thickness 0.65mm, specific volume 25.4cm 3 / g, drape coefficient was 0.23, breaking strength was 38.8 N / 5 cm, and fluffing resistance was ×.

[0055] Comparative Example 5 A web made of thermally bondable composite fiber (1) was formed by the carding method, subjected to hydroentanglement processing at a water pressure of 100 MPa, and dried in an oven at 80°C to obtain a nonwoven fabric. The intersections of the fibers were not thermally bonded throughout the entire nonwoven fabric. The basis weight of the obtained nonwoven fabric was 47.8 g / m 2 , thickness is 1.3 mm, specific volume is 27.1 cm 3 / g, drape coefficient was 0.22, breaking strength was 33.8 N / 5 cm, and fluffing resistance was ×.

[0056] The physical properties of the nonwoven fabrics obtained in the examples and comparative examples are summarized in Tables 1 and 2.

[0057] [Table 1] [Industrial Applicability]

[0058] The nonwoven fabric of the present invention has excellent flexibility while suppressing loss of strength and fuzzing, and therefore can be suitably used as a surface material for absorbent articles such as disposable diapers and sanitary napkins. It can also be used as sanitary materials such as sanitary masks, gowns, and surgical gowns. It can also be used for various textile products that require excellent flexibility while suppressing loss of strength and fuzzing, such as interior materials such as wall sheets, shoji paper, and flooring; household materials such as cover cloths, cleaning wipers, and food waste covers; toiletry products such as disposable toilets and toilet covers; pet supplies such as pet sheets, pet diapers, and pet towels; industrial materials such as wiping materials, filters, cushioning materials, oil adsorbents, and adsorbents for ink tanks; covering materials, poultry patches, bedding, and nursing care products. [Explanation of symbols]

[0059] 1: Camera 2:Disc 3: Nonwoven fabric sample 4: Cylinder base

Claims

1. A nonwoven fabric containing thermally adhesive conjugate fibers composed of a high-melting point component mainly composed of a polyester-based resin and a low-melting point component mainly composed of a thermoplastic resin having a melting point lower than that of the polyester-based resin, wherein intersections of the thermally adhesive conjugate fibers are thermally bonded across the entire nonwoven fabric, and the nonwoven fabric has a drape coefficient of 0.1 to 0.

5.

2. 2. The nonwoven fabric according to claim 1, which has a thickness change rate of 50% or less when heat-treated at 100°C for 5 minutes.

3. 3. The nonwoven fabric according to claim 1, wherein the thermoplastic resin of the low melting point component is a polyolefin resin.

4. A method for producing a nonwoven fabric, comprising the steps of: forming a web containing thermally adhesive conjugate fibers composed of a high-melting point component mainly composed of a polyester-based resin and a low-melting point component mainly composed of a thermoplastic resin having a melting point lower than that of the polyester-based resin; thermally bonding intersections of the thermally adhesive conjugate fibers throughout the entire web; and, after the thermal bonding step, consolidating the web at a temperature ranging from +10°C above the glass transition temperature of the polyester-based resin to -10°C below the melting point of the thermoplastic resin of the low-melting point component.

5. An absorbent article using the nonwoven fabric according to claim 1 or 2.

6. A sanitary material using the nonwoven fabric according to claim 1 or 2.

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