Nonwoven fabric and sheet-like padding using same

Abstract

Provided is a nonwoven fabric excellent in balance among heat retension properties, shape stability and flexibility, and that can be made compact.　This nonwoven fabric is obtained by mixing 20-80 wt. %, relative to the weight of the nonwoven fabric, of thermally bonding conjugate fibers having a fineness of 0.5-8 dtex fineness, with 20-80 wt. %, relative to the weight of the nonwoven fabric, of non-thermally bonding fibers having a fineness of 0.5-5 dtex. The intersections of the thermally bonding conjugate fibers are thermally bonded, and their specific volume is 150-400 cm3 / g.

Description

Nonwoven fabric and sheet-like batting using the same

[0001] This invention relates to a nonwoven fabric that offers an excellent balance of heat retention, shape stability, and flexibility, and can be made compact.

[0002] Traditionally, natural and synthetic fibers have been proposed as fillings for bedding and clothing. Among natural fiber fillings, those using down and feathers are well-known and widely used due to their excellent heat retention and texture. However, fillings made of down and feathers have the problem that their loft decreases and heat retention decreases when wet. In addition, because they are cotton-like and not integrated as a single filling, they are difficult to handle, and the filling tends to shift within bedding and clothing, resulting in reduced heat retention in thinned areas. Furthermore, it is necessary to apply down-proof processing to the outer fabric to prevent down from escaping, and down needs to be blown into a bag-like structure to suppress the shifting of down, which limits product design and other aspects. Moreover, from the perspective of animal protection, stricter regulations on capture and harvesting have made the supply unstable, and it has been pointed out that they may cause allergies depending on the wearer's constitution.

[0003] As an alternative to natural fibers, granular padding made from synthetic fibers has been proposed. Synthetic fibers have advantages over natural fibers, such as lower moisture absorption, less loss of heat retention even when wet, stable supply, and a lower risk of allergies. However, they are less bulky than natural fibers, inferior in heat retention and texture, and because they are not integrated as padding, problems such as handling difficulties, uneven distribution of padding, and limitations in product design remain.

[0004] In contrast to these types of padding, sheet-like padding using synthetic fibers has been proposed. Sheet-like padding offers the advantages of synthetic fibers mentioned above, and because it is integrated as padding, it is easy to handle, less prone to uneven distribution within the product, and is attracting attention as a material that offers greater freedom in product design. Patent Document 1 proposes a padding containing short fibers A and B of specific fineness in a specific mixing ratio. It is described that such padding can produce padding and clothing that is bulky, has excellent heat retention, and is also easy to process. However, the padding in Patent Document 1 has low shape stability because no bonding points are formed between the fibers. For example, it is prone to breakage when rolled or processed into products, and when the product is folded or stored, it does not easily regain its bulk, resulting in reduced heat retention. Furthermore, Patent Document 2 discloses a nonwoven fabric composed of 5-80% by weight of polyester short fibers and 95-20% by weight of heat-adhesive fibers. However, the nonwoven fabric disclosed in Patent Document 2 has low bulk and does not provide sufficient heat retention. Furthermore, the applicant previously proposed a bulky, highly flexible, and relatively high-strength nonwoven fabric by heat-sealing the intersections of heat-adhesive composite fibers under atmospheric pressure using superheated steam gas (Patent Document 3). However, the nonwoven fabric obtained in this way had relatively strong rebound when compressed, and there was room for improvement in terms of flexibility and compactness when storing products using this nonwoven fabric.

[0005] Japanese Patent Publication No. 2023-157431, Japanese Patent Publication No. 2001-271257, International Publication No. 2022 / 202142

[0006] This invention is based on the prior art described above, and its purpose is to provide a nonwoven fabric that has an excellent balance of heat retention, shape stability, and flexibility, and can be made compact.

[0007] The inventors diligently conducted research to solve the above-mentioned problems. As a result, they discovered that in a nonwoven fabric made by mixing heat-adhesive composite fibers and non-heat-adhesive fibers, by setting the fineness and mixing ratio of the heat-adhesive composite fibers and non-heat-adhesive fibers within a specific range, heat-bonding the intersections of the heat-adhesive composite fibers, and setting the specific volume within a specific range, a nonwoven fabric with an excellent balance of heat retention, shape stability, and flexibility, and that can be made compact, can be obtained, leading to the completion of the present invention.

[0008] In other words, the present invention has the following configuration: [1] A nonwoven fabric in which heat-adhesive composite fibers with a fineness of 0.5 to 8.0 dtex are mixed in a ratio of 20 to 80% by weight relative to the weight of the nonwoven fabric, and non-heat-adhesive fibers with a fineness of 0.5 to 5.0 dtex are mixed in a ratio of 20 to 80% by weight relative to the weight of the nonwoven fabric, wherein the intersections of the heat-adhesive composite fibers are heat-bonded, and the specific volume of the nonwoven fabric is 150 to 400 cm³. ３ [1] A nonwoven fabric having a density of 10% / g. [2] The nonwoven fabric according to [1], wherein the heat-adhesive composite fiber is a sheath-core type composite fiber in which a polyolefin resin is arranged on the sheath side as a low-melting-point component and a polyester resin is arranged on the core side as a high-melting-point component. [3] The nonwoven fabric according to [1] or [2], wherein the biomass content of the nonwoven fabric is 10% or more. [4] The nonwoven fabric according to any one of [1] to [3], wherein the non-heat-adhesive fiber is polyethylene terephthalate fiber. [5] The nonwoven fabric according to any one of [1] to [3], wherein the non-heat-adhesive fiber is hollow polyethylene terephthalate fiber. [6] The nonwoven fabric according to any one of [1] to [3], wherein the non-heat-adhesive fiber is biodegradable polyethylene terephthalate fiber. [7] The nonwoven fabric according to any one of [1] to [3], wherein the non-heat-adhesive fiber is polytrimethylene terephthalate fiber. [8] A sheet-like batting using the nonwoven fabric according to any one of [1] to [7].

[0009] According to the present invention, it is possible to provide a nonwoven fabric that has an excellent balance of heat retention, shape stability, and flexibility, and can be made compact.

[0010] The non-woven fabric of the present invention is a non-woven fabric in which heat-adhesive composite fibers and non-heat-adhesive fibers are mixed, the intersections of the heat-adhesive composite fibers are heat-bonded, the fineness of the heat-adhesive composite fibers is 0.5 to 8.0 dtex, the fineness of the non-heat-adhesive fibers is 0.5 to 5.0 dtex, the mixing ratio of the heat-adhesive composite fibers is 20 to 80% by weight based on the weight of the non-woven fabric, the mixing ratio of the non-heat-adhesive fibers is 20 to 80% by weight based on the weight of the non-woven fabric, and the specific volume of the non-woven fabric is 150 to 400 cm ３ / g.

[0011] (Heat-adhesive composite fiber) The heat-adhesive composite fiber in the present invention is not particularly limited as long as it can be melted by heat to form an adhesive point, and the composite form thereof can be exemplified by a concentric sheath-core type composite fiber, an eccentric sheath-core type composite fiber, a并列型复合纤维 (parallel type composite fiber), a segmented type composite fiber, or an island-in-sea type composite fiber. Further, the cross-sectional shape of the composite fiber is not particularly limited, and any of a round shape such as a circle or an ellipse, a square shape such as a triangle or a square, a异型 (peculiar shape) such as a star or an octagonal shape, or a hollow shape can be used.

[0012] It should be noted that the Chinese term "并列型复合纤维" in the original text seems to be a misspelling. It might be intended to be "并列型复合纤维 (parallel type composite fiber)". Also, "异型" is a literal translation of the Chinese term, which might be better expressed as "peculiar shape" or something more descriptive in English for a more accurate understanding.The resin constituting the heat-adhesive composite fiber in the present invention is not particularly limited, and examples include polyolefin resins such as low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), high-density polyethylene (HDPE), crystalline polypropylene (PP), or copolymers of propylene and α-olefin (excluding propylene) (Co-PP) with propylene as the main component; polyester resins such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), copolymerized polyethylene terephthalate (Co-PET), polylactic acid (PLA), polyglycolic acid (PGA), or polybutylene succinate (PBS); polyvinyl alcohol resins, polyvinyl acetate resins, acrylic resins, polystyrene resins, polyurethane resins, polyamide resins, or fluorine resins. While there are no particular limitations on the combination of resins constituting the heat-adhesive composite fiber, from the viewpoint of broadening the processing temperature range, it is preferable that the melting point difference be 10°C or more, more preferably 30°C or more, and even more preferably 50°C or more. Examples include PP / HDPE, PP / LLDPE, PP / Co-PP, PET / HDPE, PET / LLDPE, PET / Co-PET, and PET / PP. Furthermore, from the viewpoint of heat adhesion, it is preferable that the low-melting-point component occupies 50% or more of the surface area of ​​the heat-adhesive composite fiber, and more preferably 70% or more. In particular, it is preferable to use a sheath-core type composite fiber in which a polyolefin resin is arranged on the sheath side as the low-melting-point component and a polyester resin is arranged on the core side as the high-melting-point component. The polyolefin in the sheath component strengthens the adhesion points of the heat-adhesive composite fiber, improving shape stability, as well as improving quick-drying properties and flexibility. Furthermore, the polyester in the core component increases the specific volume of the nonwoven fabric, improving heat retention, flexibility, and shape stability.

[0013] The volume ratio of the low melting point component to the high melting point component is not particularly limited. However, when the proportion of the low melting point component is large, the adhesive point strength between the thermally adhesive composite fibers is improved, and the strength of the non-woven fabric is likely to be improved. When the proportion of the high melting point component is large, in addition to the bulkiness and flexibility of the non-woven fabric being improved, the thickness is less likely to change due to a load. From such a perspective, the volume ratio of the low melting point component to the high melting point component is preferably 20 / 80 to 80 / 20, and more preferably 30 / 70 to 70 / 30.

[0014] The resin constituting the thermally adhesive composite fiber may contain additives such as an antioxidant, a light stabilizer, an ultraviolet absorber, a neutralizing agent, a nucleating agent, an epoxy stabilizer, a lubricant, an antibacterial agent, a deodorant, a flame retardant, an antistatic agent, a pigment, or a plasticizer, as long as the effects of the present invention are not impaired.

[0015] It is important that the fineness of the thermally adhesive composite fiber in the present invention is 0.5 to 8.0 dtex. If it is 0.5 dtex or more, it has excellent fibrillation properties, and not only can a uniform non-woven fabric be obtained, but also the adhesive points of the thermally adhesive composite fiber do not increase too much, so the flexibility is improved and compactification is possible. From such a perspective, the fineness of the thermally adhesive composite fiber is preferably 0.6 dtex or more, and more preferably 0.7 dtex or more. Also, if it is 8.0 dtex or less, not only can the heat retention property be enhanced, but also the adhesive points of the thermally adhesive composite fiber are sufficient, and the shape stability of the non-woven fabric is improved. From such a perspective, the fineness of the thermally adhesive composite fiber is preferably 6.0 dtex or less, and more preferably 5.0 dtex or less.

[0016] The fiber length of the thermally adhesive composite fiber is not particularly limited. However, in order to increase the entanglement between the fibers and improve the shape stability of the non-woven fabric, it is preferably 3 mm or more, more preferably 20 mm or more, and even more preferably 30 mm or more. Also, in order to improve the bulkiness and flexibility of the non-woven fabric, the fiber length is preferably 200 mm or less, more preferably 120 mm or less, and even more preferably 60 mm or less.

[0017] The crimping of heat-bondable composite fibers is not particularly limited, and the crimping characteristics such as the number of crimps, crimping rate, residual crimping rate, and crimping modulus should be appropriately selected considering the bulkiness, flexibility, and mechanical properties of the nonwoven fabric. Furthermore, the shape of the crimp is not particularly limited, and can be appropriately selected from zigzag mechanical crimping, spiral crimping, or ohm-shaped three-dimensional crimping.

[0018] (Non-heat-adhering fibers) The non-heat-adhering fibers in this invention are fibers that do not melt during the heat treatment applied to the web described later, and do not contribute to the adhesion of fibers to each other, but rather provide the mobility of the fibers within the nonwoven fabric. For example, it is preferable to use non-heat-adhering fibers whose melting point or softening point is 15°C or higher than that of the low-melting-point component of the heat-adhering composite fiber. Such non-heat-adhering fibers are not particularly limited, and examples include natural fibers such as cotton, silk, linen, and wool, semi-synthetic fibers such as acetate, regenerated fibers such as rayon and cupro, and synthetic fibers such as polypropylene, polyester, acrylic, nylon, and vinylon, but polyester fibers are preferred due to their high heat resistance, low moisture absorption, and availability. The polyester fibers are not particularly limited, and examples include polyethylene terephthalate (PET) fibers, polybutylene terephthalate (PBT) fibers, polytrimethylene terephthalate (PTT) fibers, polylactic acid (PLA) fibers, polyglycolic acid (PGA) fibers, polybutylene succinate (PBS) fibers, and composite fibers thereof. Among these, polyethylene terephthalate, polytrimethylene terephthalate, and composite fibers of polyethylene terephthalate and polytrimethylene terephthalate are preferred.

[0019] The non-heat-adhesive fibers in this invention may be solid or hollow, but they are preferably hollow in order to easily improve heat retention. The hollowness ratio of the non-heat-adhesive fibers is not particularly limited, but for improved heat retention, it is preferably 5% or more, more preferably 10% or more, and even more preferably 15% or more. Furthermore, in order to easily improve the shape stability of the nonwoven fabric, it is preferably 50% or less, more preferably 45% or less, and even more preferably 40% or less.

[0020] The non-heat-adhesive fibers in the present invention are not particularly limited, but it is preferable that they be biodegradable. Biodegradability of non-heat-adhesive fibers makes it easier to reduce the impact on ecosystems and the environment caused by microplastic formation. Biodegradable fibers can be made from materials that are inherently biodegradable, such as polylactic acid or polybutylene succinate, or from fibers to which biodegradability has been imparted through additives. Examples of biodegradable fibers include those described in Japanese Patent Publication No. 2023-121674, International Publication No. 2019 / 136049, International Publication No. 2020 / 134498, and synthetic fibers to which commercially available biodegradation-promoting additives have been added.

[0021] Non-heat-adhesive fibers are not particularly limited, but preferably have a biomass content of 10% or more, more preferably 20% or more, and even more preferably 30% or more. A biomass content of 10% or more makes it easier to reduce the amount of petroleum resources used. Examples of such non-heat-adhesive fibers include polylactic acid fibers and polyalkylene terephthalate fibers derived from biomass resources. While not particularly limited, examples of polyalkylene terephthalate fibers derived from biomass resources include polyethylene terephthalate fibers (30% biomass content) made from ethylene glycol derived from biomass resources and terephthalic acid derived from petroleum resources, and polytrimethylene terephthalate fibers (38% biomass content) made from 1,3-propanediol derived from biomass resources and terephthalic acid derived from petroleum resources.

[0022] Here, the biomass degree in this invention refers to radioactive carbon ( １４ C) This refers to the measured value of the carbon content derived from biomass. Specifically, atmospheric carbon dioxide contains １４ Because it contains a certain percentage of carbon (107 pMC (percent modern carbon)), it is useful for plants that take in carbon dioxide from the atmosphere to grow, such as corn. １４ It is also known that the C content is approximately 107 pMC. １４Carbon dioxide (C) has a half-life of 5,370 years and returns to nitrogen atoms, and it takes 226,000 years for it to completely decay. Therefore, in fossil fuels such as coal, oil, and natural gas, which are thought to have been absorbed and fixed by plants and other organisms for more than 226,000 years, １４ It is known that it contains almost no carbon. Therefore, the total carbon atoms in the resin are １４ By measuring the proportion of C, the biomass content can be calculated.

[0023] Non-heat-adhesive fibers are not particularly limited, but may contain functional materials such as aerogels, infrared radiators, or infrared absorbers to improve heat retention. The content of these functional materials is not particularly limited, but examples include 10 to 90 volume percent. Examples of such non-heat-adhesive fibers include polyester, nylon, acrylic, rayon, or polyolefin fibers on which functional materials are supported by printing or coating, or fibers in which functional materials are kneaded into the interior.

[0024] Non-heat-adhesive fibers are not particularly limited, but may contain temperature-regulating functional materials such as phase-change materials (PCMs) to improve wearer comfort. The content of these functional materials is not particularly limited, but examples include 10 to 90 volume percent. Examples of such non-heat-adhesive fibers include those in which paraffin wax encapsulated in resin is supported on the surface of polyester, nylon, acrylic, rayon, or polyolefin fibers by printing or coating, or in which it is kneaded into the fiber, and sheath-core composite fibers in which a polymer-type phase-change material is used as the core component and a thermoplastic resin such as polyester, nylon, acrylic, rayon, or polyolefin is used as the sheath component.

[0025] In the present invention, it is important that the fineness of the non-heat-adhesive fibers be 0.5 to 5.0 dtex. If it is 0.5 dtex or more, a uniform nonwoven fabric can be obtained with excellent fiber opening properties in carding and less unevenness in heat retention. If it is 5.0 dtex or less, convection is suppressed and heat retention is improved, as well as rebound against compression is reduced, improving flexibility and enabling compactness. From this viewpoint, the fineness of the non-heat-adhesive fibers is preferably 0.6 dtex or more, and more preferably 0.7 dtex. Furthermore, the upper limit of the fineness is preferably 4.0 dtex or less, and more preferably 3.0 dtex or less.

[0026] The fiber length of the non-heat-adhesive fibers is not particularly limited, but in order to increase the intertwining of the fibers and improve the shape stability of the nonwoven fabric, it is preferably 3 mm or longer, more preferably 20 mm or longer, and even more preferably 30 mm or longer. Furthermore, in order to improve the bulkiness and flexibility of the nonwoven fabric, the fiber length is preferably 200 mm or less, more preferably 120 mm or less, and even more preferably 60 mm or less.

[0027] The crimping of non-heat-bondable fibers is not particularly limited, and the crimping characteristics such as the number of crimps, crimping rate, residual crimping rate, and crimping modulus should be appropriately selected considering the bulkiness, flexibility, and mechanical properties of the nonwoven fabric. Furthermore, the shape of the crimp is not particularly limited, and can be appropriately selected from zigzag mechanical crimping, spiral crimping, or ohm-shaped three-dimensional crimping.

[0028] (Nonwoven Fabric) The nonwoven fabric of the present invention is a mixture of the aforementioned heat-adhesive composite fibers and non-heat-adhesive fibers in a specific ratio, and it is important that the intersections of the heat-adhesive composite fibers are heat-bonded. The formation of bonding points of the heat-adhesive composite fibers improves strength and makes it less likely to break during processing, as well as improving recovery from a compressed state and improving shape stability against various stresses.

[0029] The non-woven fabric of the present invention is importantly characterized in that the mixing ratio of the above-described heat-adhesive composite fibers is 20 to 80% by weight based on the weight of the non-woven fabric. If the mixing ratio of the heat-adhesive composite fibers is 20% by weight or more, the bonding points are sufficient and the shape stability is improved. Also, if the mixing ratio is 80% by weight or less, the flexibility is improved and compactification becomes possible. From such a viewpoint, as the lower limit of the mixing ratio of the heat-adhesive composite fibers, it is preferably 30% by weight or more, more preferably 40% by weight or more, and even more preferably 50% by weight or more. Further, as the upper limit of the mixing ratio, it is preferably 75% by weight or less, more preferably 70% by weight or less, and even more preferably 65% by weight or less.

[0030] The non-woven fabric of the present invention is importantly characterized in that the mixing ratio of the above-described non-heat-adhesive fibers is 20 to 80% by weight based on the weight of the non-woven fabric. If the mixing ratio of the non-heat-adhesive fibers is 20% by weight or more, mobility is imparted to the fibers in the non-woven fabric, the flexibility is improved, and compactification becomes possible. Also, if the mixing ratio is 80% by weight or less, the shape stability is improved. From such a viewpoint, as the lower limit of the mixing ratio of the non-heat-adhesive fibers, it is preferably 25% by weight or more, more preferably 30% by weight or more, and even more preferably 35% by weight or more. Further, as the upper limit of the mixing ratio, it is preferably 70% by weight or less, more preferably 60% by weight or less, and even more preferably 50% by weight or less.

[0031] The non-woven fabric of the present invention is importantly characterized in that the specific volume is 150 to 400 cm ３ / g. If the specific volume is 150 cm ３ / g or more, a large amount of air is contained in the non-woven fabric and the heat retention property is improved. Also, if it is 400 cm ３ / g or less, the bonding points of the heat-adhesive composite fibers increase and the shape stability is improved. From such a viewpoint, as the lower limit of the specific volume, it is preferably 155 cm ３ / g or more, more preferably 160 cm ３ / g or more. Further, as the upper limit of the specific volume, it is preferably 380 cm ３ / g or less, more preferably 350 cm ３It is more preferable that the amount is less than or equal to / g.

[0032] The nonwoven fabric of the present invention is not particularly limited, but preferably has a biomass content of 5% or more, more preferably 10% or more, and even more preferably 30% or more. A biomass content of 5% or more makes it easier to reduce the amount of petroleum resources used. To obtain a nonwoven fabric with a biomass content of 10% or more, the aforementioned non-heat-adhesive fibers with a biomass content of 10% or more can be mixed in a predetermined proportion. For example, by mixing non-heat-adhesive fibers with a biomass content of 30% in a proportion of 50% by weight, a nonwoven fabric with a biomass content of 15% can be obtained.

[0033] The average fiber diameter of the fibers constituting the nonwoven fabric is not particularly limited, but in order to obtain a nonwoven fabric with excellent fiber-opening properties and uniformity, it is preferably 6 μm or more, more preferably 7 μm or more, and even more preferably 8 μm or more. Furthermore, in order to improve the heat retention properties of the nonwoven fabric, it is preferably 20 μm or less, more preferably 18 μm or less, and even more preferably 16 μm or less.

[0034] The I-value of nonwoven fabric is not particularly limited, but to improve the heat retention of nonwoven fabric, 10 cm ３ Preferably, the concentration is 12 cm or more / g / μm. ３ It is more preferably 15 cm or more / g / μm, ３ It is even more preferable that the concentration is 1 / g / μm or higher. In addition, in order to improve the shape stability of the nonwoven fabric, 50 cm ３ Preferably, the concentration is less than or equal to / g / μm, and at 45 cm. ３ It is more preferable that the concentration be less than or equal to / g / μm, and at 40 cm ３ It is even more preferable that the concentration is less than or equal to / g / μm. In this invention, the I value is defined as the value expressed by the following relational formula: I value = Specific volume of nonwoven fabric (cm³) ３ ( / g) ÷ Average fiber diameter (μm) of the fibers constituting the nonwoven fabric

[0035] The basis weight of the nonwoven fabric is not particularly limited, but to improve heat retention, 10 g / m is recommended. ２ Preferably, it is 15 g / m ２It is more preferable that the amount be greater than or equal to 20 g / m². ２ It is even more preferable that the above conditions are met. Furthermore, from the viewpoint of lightness, a basis weight of 200 g / m is desirable. ２ Preferably, it is 150 g / m ２ It is more preferable that the following conditions apply: 100 g / m ２ The following is even more preferable:

[0036] The initial thickness of the nonwoven fabric is not particularly limited, but to improve heat retention, it is preferably 1 mm or more, more preferably 2 mm or more, and even more preferably 3 mm or more. Furthermore, to improve flexibility, it is preferably 50 mm or less, more preferably 30 mm or less, and even more preferably 20 mm or less.

[0037] The compressibility of the nonwoven fabric is not particularly limited, but it is preferably 88% or higher, and more preferably 93% or higher, in order to facilitate compact manufacturing. The method for measuring the compressibility of the nonwoven fabric will be described in detail in the examples.

[0038] The recovery rate of the nonwoven fabric is not particularly limited, but it is preferably 78% or higher, and more preferably 88% or higher, in order to improve shape stability. The method for measuring the recovery rate of the nonwoven fabric will be described in detail in the examples.

[0039] The average strength of the nonwoven fabric is not particularly limited, but is preferably 1 N / 50 mm or higher, and more preferably 5 N / 50 mm or higher, in order to improve shape stability. The method for measuring the average strength of the nonwoven fabric will be described in detail in the examples.

[0040] The average stiffness of the nonwoven fabric is not particularly limited, but is preferably less than 12 mm, and more preferably less than 8 mm, in order to improve flexibility in the bending direction. The method for measuring the average stiffness of the nonwoven fabric will be described in detail in the examples.

[0041] The compression stiffness of the nonwoven fabric is not particularly limited, but is preferably less than 0.3, and more preferably less than 0.2, in order to improve flexibility in the thickness direction. The method for measuring the compression stiffness of the nonwoven fabric will be described in detail in the examples.

[0042] The heat retention rate of the nonwoven fabric is not particularly limited, but to enhance heat retention, it is preferably 50% or more, more preferably 55% or more, and even more preferably 60% or more.

[0043] The clo value of the nonwoven fabric is not particularly limited, but is preferably 0.50 clo or higher, more preferably 0.65 clo or higher, and even more preferably 0.80 clo or higher.

[0044] The clo value per basis weight of the nonwoven fabric is not particularly limited, but is preferably 0.015 clo or higher, more preferably 0.018 clo or higher, even more preferably 0.020 clo or higher, and particularly preferably 0.022 clo or higher. It is known that the clo value is generally proportional to the basis weight of the nonwoven fabric. Therefore, the clo value per basis weight, calculated by dividing the clo value by the basis weight, can be used as an indicator of the superiority or inferiority of the heat retention properties of the nonwoven fabric structure itself, and it is considered possible to directly compare the heat retention properties of nonwoven fabrics with different basis weights.

[0045] The fiber density of a nonwoven fabric is not particularly limited, but to increase the number of fiber intersections and improve the strength of the nonwoven fabric, it is recommended to have a density of 3 fibers / mm². ２ Preferably, it should be 5 strands / mm ２ It is more preferable that the number be 8 or more / mm ２ It is even more preferable that the above conditions are met. Furthermore, in order to improve the flexibility of the nonwoven fabric, the fiber density should be 50 fibers / mm². ２ Preferably, the following: 40 strands / mm ２ More preferably, the following is true: 30 strands / mm ２ The following is even more preferable:

[0046] The fiber density ratio between high-density and low-density areas of a nonwoven fabric is not particularly limited, but to obtain uniform properties in the thickness direction, it is preferably 1.4 or less, more preferably 1.3 or less, and even more preferably 1.2 or less. Furthermore, the lower limit of the fiber density ratio is 1.0, and the closer it is to 1.0, the closer the fiber density is to a uniform state.

[0047] Here, the fiber density ratio as used herein is expressed as the ratio of the fiber density of the high-density area to the low-density area. Furthermore, the "high-density area" and the "low-density area" refer to the area where the fiber density is measured when the nonwoven fabric is divided in half along its thickness, with the higher fiber density being the "high-density area" and the lower fiber density being the "low-density area." Furthermore, "fiber density" as used herein is expressed as the number of fibers per unit area in the cross-section of the nonwoven fabric, and the unit is, for example, fibers / mm ２ It can be done this way.

[0048] The nonwoven fabric of the present invention may contain fibers other than the heat-adhesive composite fibers or non-heat-adhesive fibers described above, to the extent that they do not impede the effects of the present invention. The content of such fibers is not limited as long as it does not hinder the effects of the present invention, but it is preferably 1 to 30% by weight relative to the weight of the nonwoven fabric.

[0049] The nonwoven fabric of the present invention may be a single-layer nonwoven fabric, or it may be a multilayer nonwoven fabric of two or more types with different fineness, composition, or density. Furthermore, the nonwoven fabric of the present invention is not particularly limited, but it may be laminated and integrated with sheet-like materials other than the nonwoven fabric of the present invention, such as through-air nonwoven fabric, spunbond nonwoven fabric, meltblown nonwoven fabric, spunlace nonwoven fabric, needle-punched nonwoven fabric, film, mesh, or net.

[0050] The nonwoven fabric of the present invention is not particularly limited, but when used for padding applications, it is preferable that a water-repellent fiber treatment agent is applied to prevent a decrease in heat retention even when wet. The components of the water-repellent fiber treatment agent are not particularly limited, but examples include silicone compounds such as polyoxyalkylene-modified silicone, dimethylpolysiloxane, amino-modified silicone, or hydroxy-modified silicone.

[0051] The amount of water-repellent fiber treatment agent applied is not particularly limited, but in order to improve the water repellency of the nonwoven fabric, it is preferably 0.01% by weight or more, more preferably 0.05% by weight or more, and even more preferably 0.1% by weight or more, relative to the weight of the nonwoven fabric. Furthermore, in order to reduce contamination of processing equipment, etc., it is preferably 1.0% by weight or less, more preferably 0.8% by weight or less, and even more preferably 0.6% by weight or less.

[0052] The method for applying the water-repellent fiber treatment agent is not particularly limited, but any known method of application may be used, such as obtaining a nonwoven fabric using heat-adhesive composite fibers to which the water-repellent fiber treatment agent has been applied to the surface or interior of the fibers, immersing the nonwoven fabric in the water-repellent fiber treatment agent, or spraying the water-repellent fiber treatment agent onto the nonwoven fabric.

[0053] The nonwoven fabric of the present invention may be subjected to treatments such as water-repellent treatment, moisture-absorbing treatment, moisture-absorbing heat-generating treatment, antibacterial treatment, deodorizing treatment, infrared emission treatment, temperature control treatment, shrinkage prevention treatment, or stain-resistant treatment, as long as the effects of the present invention are not impaired.

[0054] (Method for Manufacturing Nonwoven Fabric) The method for manufacturing the nonwoven fabric of the present invention is not particularly limited, but it is preferable to include a step of forming a web in which the aforementioned heat-adhesive composite fibers and non-heat-adhesive fibers are mixed (hereinafter sometimes referred to as the "web forming step"), and a step of heat-bonding the intersections of the heat-adhesive composite fibers by heat-treating the web (hereinafter sometimes referred to as the "heat treatment step"). In the web forming step, it is preferable to form the web such that the mixing ratio of heat-adhesive composite fibers is 20 to 80% by weight relative to the weight of the nonwoven fabric, and the mixing ratio of non-heat-adhesive fibers is 20 to 80% by weight relative to the weight of the nonwoven fabric. With such a manufacturing method, it is possible to bond the intersections of the heat-adhesive composite fibers while maintaining bulkiness and leaving a certain degree of fiber mobility, and it is possible to obtain a nonwoven fabric that has an excellent balance of heat retention, shape stability and flexibility, and can be made compact.

[0055] (Web Forming Process) The method for forming a web containing heat-adhesive composite fibers and non-heat-adhesive fibers is not particularly limited. It may be a short-fiber web formation method using the carding method, airlaid method, or wet method with short fibers (staples or chops) of the heat-adhesive composite fibers and non-heat-adhesive fibers described above, or a long-fiber web formation method such as the spunbond method, meltblown method, or tow opening method. However, the carding method is preferred in order to easily obtain the desired specific volume. In this invention, "web" refers to a fiber aggregate in which fibers are entangled to some extent, and the intersections of the heat-adhesive composite fibers are not bonded.

[0056] (Heat Treatment Process) Next, the obtained web is heat-treated to heat-bond the intersections of the heat-adhesive composite fibers. Here, in order to easily obtain a specific volume within a particular range, examples include blowing a heat transfer medium with an air velocity of preferably 0.5 m / s or less, more preferably 0.2 m / s or less, and even more preferably 0.1 m / s or less from the top or bottom surface of the web, or introducing the web into a furnace (under no-wind conditions) filled with the heat transfer medium. The heat transfer medium is not particularly limited, and examples include hot air or superheated steam, but from the viewpoint of the mechanical properties of the nonwoven fabric and productivity, it is preferable to use superheated steam. The above heat treatment may be carried out under atmospheric pressure, high pressure, low pressure, or vacuum, but from the viewpoint of simplifying the equipment, it is preferable to carry it out under atmospheric pressure. Furthermore, in the heat treatment process, it is preferable to introduce the web into the furnace using a conveyor belt or the like and continuously obtain the nonwoven fabric.

[0057] The temperature of the heat transfer medium is not particularly limited, but if it is higher than the melting or softening point of the low-melting-point component constituting the heat-adhesive composite fiber, lower than the melting or softening point of the high-melting-point component constituting the heat-adhesive composite fiber, and lower than the melting or softening point of the non-heat-adhesive fiber, it will suppress web deformation and facilitate bonding of the intersections of the heat-adhesive composite fibers while preserving fiber mobility. From this viewpoint, the lower limit of the temperature of the heat transfer medium is more preferably 10°C or more higher than the melting or softening point of the low-melting-point component constituting the heat-adhesive composite fiber, and even more preferably 20°C or more higher than the melting or softening point of the low-melting-point component constituting the heat-adhesive composite fiber. Furthermore, the upper limit of the temperature of the heat transfer medium is more preferably 10°C or more lower than the melting point or softening point of the high-melting-point component constituting the heat-adhesive composite fiber, and 10°C or more lower than the melting point or softening point of the non-heat-adhesive fiber, and even more preferably 20°C or more lower than the melting point or softening point of the high-melting-point component constituting the heat-adhesive composite fiber, and 20°C or more lower than the melting point or softening point of the non-heat-adhesive fiber.

[0058] The processing time for the heat treatment process is not particularly limited, but is preferably 60 seconds or less, and more preferably 30 seconds or less. If the processing time is 60 seconds or less, it is possible to manufacture nonwoven fabrics with satisfactory productivity.

[0059] The nonwoven fabric of the present invention can be suitably used as padding for bedding such as comforters, mattresses, and pillows; padding for clothing such as down jackets and quilted fabrics; and padding for outdoor equipment such as sleeping bags and cooler bags. It is particularly suitable for clothing, especially for padding in down jackets. It can also be used in a wide range of other items, including absorbent items such as diapers, napkins, and incontinence pads; sanitary materials such as masks, gowns, surgical gowns, and bandages; interior materials such as wall sheets, shoji paper, and flooring materials; lifestyle-related materials such as cover cloths, cleaning wipers, and garbage covers; toiletries 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 absorbents, abrasives, and adsorbents for ink tanks; and textile products such as general medical materials, bedding, and nursing care products.

[0060] The present invention will be described in detail below with reference to examples, but the present invention is not limited thereto. The methods or definitions for measuring the physical properties shown in the examples are shown below. Furthermore, all physical property measurements below were performed after the nonwoven fabric was heat-treated in an oven at 110°C for 5 minutes to reset the stress of the nonwoven fabric.

[0061] <Fineness of heat-bondable composite fibers and non-heat-bondable fibers> The fineness of heat-bondable composite fibers and non-heat-bondable fibers was measured in accordance with JIS L 1015.

[0062] <Presence or absence of thermal bonding at the intersections of composite fibers> Using a scanning electron microscope (Hitachi High-Tech Corporation, SU-8000), the nonwoven fabric was observed at magnifications of 100 to 500 times to confirm whether bonding points were formed at the fiber intersections.

[0063] <Average fiber diameter of fibers constituting the nonwoven fabric> The nonwoven fabric was photographed at a magnification of 100 to 200 times using a scanning electron microscope (Hitachi High-Tech Corporation, SU-8000). The fiber diameter of the fibers constituting the nonwoven fabric was measured using image analysis software (ImageJ). The fiber diameter was the average value when 50 fibers were measured.

[0064] <Hollow Ratio of Non-Heat-Adhesive Composite Fibers> Using a scanning electron microscope (Hitachi High-Tech Corporation, SU-8000), cross-sections of non-heat-adhesive fibers were photographed at magnifications of 100 to 1000 times. Using image analysis software (ImageJ), the total area of ​​the fiber cross-section including the hollow portion and the area of ​​the hollow portion were measured, and the hollow ratio of the non-heat-adhesive fibers was calculated using the following formula: Hollow ratio of non-heat-adhesive fibers (%) = Area of ​​the hollow portion (μm²) ２ ) ÷ total area (μm ２ ) × 100

[0065] <Biomass content of non-heat-adhesive fibers and nonwoven fabrics> The biomass content of non-heat-adhesive fibers and nonwoven fabrics was measured in accordance with ASTM D6866. Specifically, the total carbon content and biomass-derived carbon content were measured using an accelerator mass spectrometer (AMS). １４ C) The amount was measured. The total amount of carbon obtained and １４ The biomass percentage was calculated from the amount of carbon using the following formula: Biomass percentage (%) = Carbon derived from biomass in the sample１４ C) Amount ÷ Total amount of carbon in the sample × 100

[0066] <Balance Weight> The weight of a 150mm x 150mm piece of nonwoven fabric is measured and converted to a value per unit area to determine the basis weight (g / m²) of the nonwoven fabric. ２ The weight was calculated as the average of two measurements.

[0067] <Thickness> 0.1 gf / cm² on a nonwoven fabric cut to 150 mm x 150 mm ２ A plate with a pressure of (9.8 Pa) was placed on the nonwoven fabric, and the thickness of the fabric was measured after 1 minute to determine the initial thickness T1 (mm). After measuring the initial thickness T1, 9.9 gf / cm was applied to the plate. ２ A weight of (970.2 Pa) was placed on top, for a total pressure of 10 gf / cm². ２ The pressure was set to (980 Pa), and the thickness of the nonwoven fabric was measured after 1 minute to determine the compressed thickness T2 (mm). After measuring the compressed thickness T2, 9.9 gf / cm was measured. ２ Remove the weight and the reading is 0.1 gf / cm ２ The thickness of the nonwoven fabric was measured after one minute and defined as the recovered thickness T3 (mm). T1, T2, and T3 were all average values ​​obtained from measurements taken at five locations.

[0068] <Specific volume> Basis weight (g / m³) obtained above ２ The specific volume of the nonwoven fabric was calculated from the initial thickness T1 (mm) using the following formula: Specific volume (cm³) ３ (g / m) = T1 (mm) ÷ Basis weight (g / m) ２ ) × 1000

[0069] <Compression Ratio> The compression ratio of the nonwoven fabric was calculated from the initial thickness T1 (mm) and compressed thickness T2 (mm) obtained above using the following formula. Note that a higher compression ratio means that the fabric can be reduced in size with a constant load, thus indicating superior compactness. Compression Ratio (%) = (T1 (mm) - T2 (mm)) ÷ T1 (mm) × 100

[0070] <Recovery Rate> The compression recovery rate of the nonwoven fabric was calculated from the initial thickness T1 (mm), compressed thickness T2 (mm), and recovered thickness T3 (mm) obtained above using the following formula. Note that a higher recovery rate indicates better shape stability. Compression recovery rate (%) = (T3 (mm) - T2 (mm)) ÷ (T1 (mm) - T2 (mm)) × 100

[0071] Specific volume (cm³) obtained above ３ The I-value of the nonwoven fabric was calculated from the fiber density ( / g) and average fiber diameter (μm) using the following formula: I-value (cm ３ / g / μm) = specific volume (cm ３ / g)÷average fiber diameter (μm)

[0072] <Average Strength> (1) MD Strength A sample cut to a size of 50 mm in the CD direction and 150 mm in the MD direction was measured using an Autograph (Shimadzu Corporation, AGX-J) with a chuck distance of 100 mm and a tensile speed of 100 mm. The maximum strength measured was defined as the MD strength (N / 50 mm). The MD strength was the average value of three measurements. (2) CD Strength A sample cut to a size of 50 mm in the MD direction and 150 mm in the CD direction was measured using the same method as the MD strength. The maximum strength measured was defined as the CD strength (N / 50 mm). (3) Average Strength The geometric mean of the MD strength and CD strength obtained by the above measurement methods was defined as the average strength. Note that a higher average strength indicates better shape stability. Average Strength (N / 50 mm) = (MD Strength (N / 50 mm) × CD Strength (N / 50 mm)) １／２

[0073] <Average Stiffness> (1) Using an MD stiffness cantilever soft nest tester (manufactured by Daiei Kagaku Seiki Seisakusho Co., Ltd.), a sample cut to a size of 50 mm in the CD direction and 150 mm in the MD direction was gently slid along the cantilever, and the length extruded when the center of the tip of the sample touched the inclined surface was measured. The average value of the four values ​​from the front, back, and both ends was taken as the MD stiffness (mm). (2) CD stiffness Using a sample cut to a size of 50 mm in the MD direction and 150 mm in the CD direction, the CD stiffness (mm) was measured in the same manner as the MD stiffness. (3) Average stiffness The arithmetic mean of the MD stiffness and CD stiffness obtained by the above measurement methods was taken as the average stiffness. Note that the smaller the average stiffness, the better the flexibility in the bending direction. Average stiffness (mm) = (MD stiffness (mm) + CD stiffness (mm)) ÷ 2

[0074] <Compression Hardness> The compression hardness (LC) was measured using a handheld compressor (Kato Tech Co., Ltd., KES-G5) as follows. First, the nonwoven fabric was placed on the sample stage, covering an area of ​​2 cm². ２ The pressure bar was applied from above the sample, with a sensitivity of 2, a speed of 0.2 mm / second, and a stress of 50 gf / cm². ２ The material was compressed to (4.9 kPa) and a stress curve Pa with respect to distance was obtained. From the obtained Pa, 0.5 gf / cm ２ Thickness T under a load of 49.0 Pa ０ (mm), 50gf / cm ２ Thickness T under a load of 4.9 kPa ｍ (mm) was calculated. Furthermore, the compression work (gf・cm / cm) was calculated using numerical processing based on the following formula (1). ２ ) was calculated. Next, T obtained by the above method ０ , T ｍ From the above and WC, the compression hardness LC (dimensionless) of the nonwoven fabric was calculated using the following formula. Note that a smaller compression hardness indicates better flexibility in the compression direction. Compression hardness LC = 2 × WC (gf・cm / cm) ２ ) ÷ (T ０ (mm)-T ｍ (mm))÷50(gf / cm ２ ) × 10

[0075] <Heat Retention Rate> The heat retention rate of the nonwoven fabric was measured in accordance with JIS L 1096 Method A. The heat retention rate was calculated as the average of two measurements. A higher heat retention rate indicates better heat retention.

[0076] <ClO Value> The clO value of the nonwoven fabric was measured in accordance with ASTM D 1518. The clO value was the average of two samples.

[0077] <Clo value per unit weight> The clo value (clo) and weight (g / m) obtained above ２ The clo value per basis weight of the nonwoven fabric was calculated using the following formula: clo value per basis weight (clo) = clo value of nonwoven fabric (clo) ÷ basis weight of nonwoven fabric (g / m²) ２ )

[0078] <Evaluation of Heat Retention> The heat retention of the clo values ​​per unit area obtained by the above method was evaluated according to the following criteria: 0.020 clo or higher... ◎ 0.018 clo or higher, less than 0.020 clo... ○ 0.015 clo or higher, less than 0.018 clo... △ Less than 0.015 clo... ×

[0079] <Evaluation of Shape Stability> The average strength and compression recovery rate obtained by the above measurement method were scored according to the following criteria, and the shape stability was evaluated based on the total score. (1) Criteria for evaluation of recovery rate Less than 78.0%... 1 point 78.0% or more, less than 88.0%... 2 points 88.0% or more... 3 points (2) Criteria for evaluation of average strength Less than 1.0 N / 50 mm... 1 point 1.0 N / 50 mm or more, less than 5.0 N... 2 points 5.0 N / 50 mm or more... 3 points (3) Evaluation of shape stability Total score of (1) and (2) is 6 points... ◎ Total score of (1) and (2) is 4 or 5 points... ○ Total score of (1) and (2) is 3 points or less... ×

[0080] <Evaluation of Flexibility> The average rigidity and compressive hardness obtained by the above measurement method were scored according to the following criteria, and the flexibility was evaluated based on the total score. (1) Criteria for evaluating average rigidity 12.0 mm or more... 1 point 8.0 mm or more, less than 12.0 mm... 2 points Less than 8.0 mm... 3 points (2) Criteria for evaluating compressive hardness 0.30 or more... 1 point 0.20 or more, less than 0.30... 2 points Less than 0.20... 3 points (3) Evaluation of flexibility Total score of (1) and (2) is 6 points... ◎ Total score of (1) and (2) is 4 or 5 points... ○ Total score of (1) and (2) is 3 points or less... ×

[0081] <Evaluation of Compactness> The compression ratio obtained by the above method was evaluated for compactness according to the following criteria: 93.0% or higher... ◎ 88.0% or higher, less than 93.0%... ○ Less than 88.0%... ×

[0082] [Example 1] As a heat-adhesive composite fiber, the core was polyethylene terephthalate (intrinsic viscosity (measured using an isogamous mixture of phenol and tetrachloroethane solvent at a concentration of 0.5 g / 100 ml and a temperature of 20°C): 0.65 dl / g, melting point 250°C), and the sheath was high-density polyethylene (density: 0.956 g / cm³). ３A concentric sheath-core composite fiber (fineness 1.7 dtex, fiber length 45 mm, hollowness: 0%, biomass content: 0%) was prepared by arranging melt flow rate (190°C, load 21.18 N): 16 g / 10 min, melting point 130°C) in a volume ratio of 50 / 50. A water-repellent fiber treatment agent was applied to the surface of this fiber at a concentration of 0.5% by weight relative to the weight of the heat-adhesive composite fiber. As a non-heat-adhesive fiber, a fiber with a fineness of 0.9 dtex (hollowness: 0%, biomass content: 0%) made of a single component polyethylene terephthalate manufactured by Shanghai Defu Lun New Materials Technology Co., Ltd. was prepared. The heat-adhesive composite fiber was mixed at a ratio of 50% by weight relative to the weight of the nonwoven fabric, and the non-heat-adhesive fiber was mixed at a ratio of 50% by weight relative to the weight of the nonwoven fabric, and a web was prepared by the carding method. Next, the obtained web was introduced into a furnace filled with 200°C superheated steam for 10 seconds to obtain a nonwoven fabric. The superheated steam velocity was 0.1 m / s or less. In the obtained nonwoven fabric, heat-bonding points were formed at the intersections of the heat-bondable composite fibers.

[0083] [Example 2] A nonwoven fabric was obtained in the same manner as in Example 1, except that the non-heat-adhesive fiber was changed to a single-component polyethylene terephthalate fiber with a fineness of 2.2 dtex (hollow ratio: 0%, biomass content: 0%) manufactured by Shanghai Defu Lun New Materials Technology Co., Ltd. In the obtained nonwoven fabric, heat-adhesive points were formed at the intersections of the heat-adhesive composite fibers.

[0084] [Example 3] A nonwoven fabric was obtained in the same manner as in Example 1, except that the non-heat-adhesive fiber was changed to a hollow fiber with a fineness of 2.8 dtex (hollowness: 30%, biomass content: 0%) made of a single component polyethylene terephthalate manufactured by Jiangsu Haike Fiber Co., Ltd. In the obtained nonwoven fabric, heat-adhesive points were formed at the intersections of the heat-adhesive composite fibers.

[0085] [Example 4] A web was prepared in the same manner as in Example 1, except that the non-heat-adhesive fiber was changed to a single-component polytrimethylene terephthalate fiber with a fineness of 1.5 dtex (hollow fraction: 0%, biomass content: 38%) manufactured by Covation Biomaterials. The obtained web was then introduced into a furnace filled with 180°C superheated steam for 10 seconds to obtain a nonwoven fabric. The wind speed of the superheated steam was 0.1 m / s or less. In the obtained nonwoven fabric, heat-adhesive points were formed at the intersections of the heat-adhesive composite fibers.

[0086] [Example 5] A nonwoven fabric was obtained in the same manner as in Example 1, except that the non-heat-adhesive fiber was changed to a single-component fiber of biodegradable polyethylene terephthalate manufactured by Jiangsu Xingheng Composite Materials Co., Ltd., with a fineness of 1.3 dtex (hollow ratio: 0%, biomass content: 0%). In the obtained nonwoven fabric, heat-adhesive points were formed at the intersections of the heat-adhesive composite fibers.

[0087] [Comparative Example 1] A nonwoven fabric was obtained in the same manner as in Example 1, except that a web consisting only of heat-adhesive composite fibers was prepared by the carding method. In the obtained nonwoven fabric, heat-bonding points were formed at the intersections of the heat-adhesive composite fibers.

[0088] [Comparative Example 2] A nonwoven fabric was obtained in the same manner as in Example 1, except that the fineness of the non-heat-adhesive fibers was changed to 6.6 dtex. In the obtained nonwoven fabric, heat-adhesive points were formed at the intersections of the heat-adhesive composite fibers.

[0089] [Comparative Example 3] A nonwoven fabric was obtained in the same manner as in Example 1, except that the non-heat-adhesive fiber was changed to a hollow fiber with a fineness of 6.6 dtex (hollowness: 30%, biomass content: 0%) made of a single component polyethylene terephthalate manufactured by Toyobo Co., Ltd. In the obtained nonwoven fabric, heat-adhesive points were formed at the intersections of the heat-adhesive composite fibers.

[0090] [Comparative Example 4] A nonwoven fabric was obtained in the same manner as in Example 3, except that the mixing ratio of heat-adhesive composite fibers was 90% by weight relative to the weight of the nonwoven fabric, and the mixing ratio of non-heat-adhesive fibers was 10% by weight relative to the weight of the nonwoven fabric. In the obtained nonwoven fabric, heat-adhesive points were formed at the intersections of the heat-adhesive composite fibers.

[0091] [Example 6] A nonwoven fabric was obtained in the same manner as in Example 3, except that the mixing ratio of heat-adhesive composite fibers was 70% by weight relative to the weight of the nonwoven fabric, and the mixing ratio of non-heat-adhesive fibers was 30% by weight relative to the weight of the nonwoven fabric. In the obtained nonwoven fabric, heat-adhesive points were formed at the intersections of the heat-adhesive composite fibers.

[0092] [Example 7] A nonwoven fabric was obtained in the same manner as in Example 3, except that the mixing ratio of heat-adhesive composite fibers was 30% by weight relative to the weight of the nonwoven fabric, and the mixing ratio of non-heat-adhesive fibers was 70% by weight relative to the weight of the nonwoven fabric. In the obtained nonwoven fabric, heat-adhesive points were formed at the intersections of the heat-adhesive composite fibers.

[0093] [Comparative Example 5] A nonwoven fabric was obtained in the same manner as in Example 3, except that the mixing ratio of heat-adhesive composite fibers was 10% by weight relative to the weight of the nonwoven fabric, and the mixing ratio of non-heat-adhesive fibers was 90% by weight relative to the weight of the nonwoven fabric. In the obtained nonwoven fabric, heat-adhesive points were formed at the intersections of the heat-adhesive composite fibers.

[0094] [Example 8] A nonwoven fabric was obtained in the same manner as in Example 5, except that the fineness of the heat-adhesive composite fiber was changed to 2.2 dtex and the fiber length to 51 mm. In the obtained nonwoven fabric, heat-bonding points were formed at the intersections of the heat-adhesive composite fibers.

[0095] [Example 9] A nonwoven fabric was obtained in the same manner as in Example 5, except that the fineness of the heat-adhesive composite fiber was changed to 4.4 dtex and the fiber length to 51 mm. In the obtained nonwoven fabric, heat-bonding points were formed at the intersections of the heat-adhesive composite fibers.

[0096] [Example 10] A nonwoven fabric was obtained in the same manner as in Example 5, except that the fineness of the heat-adhesive composite fiber was changed to 5.6 dtex and the fiber length to 51 mm. In the obtained nonwoven fabric, heat-bonding points were formed at the intersections of the heat-adhesive composite fibers.

[0097] [Comparative Example 6] A nonwoven fabric was obtained in the same manner as in Example 5, except that the fineness of the heat-adhesive composite fiber was changed to 9.0 dtex and the fiber length to 51 mm. In the obtained nonwoven fabric, heat-bonding points were formed at the intersections of the heat-adhesive composite fibers.

[0098] [Example 11] A nonwoven fabric was obtained in the same manner as in Example 3, except that the fineness of the heat-adhesive composite fiber was changed to 0.7 dtex and the fiber length to 38 mm. In the obtained nonwoven fabric, heat-bonding points were formed at the intersections of the heat-adhesive composite fibers.

[0099] [Example 12] A nonwoven fabric was obtained in the same manner as in Example 4, except that the mixing ratio of heat-adhesive composite fibers was 70% by weight relative to the weight of the nonwoven fabric, and the mixing ratio of non-heat-adhesive fibers was 30% by weight relative to the weight of the nonwoven fabric. In the obtained nonwoven fabric, heat-adhesive points were formed at the intersections of the heat-adhesive composite fibers.

[0100] [Comparative Example 7] A nonwoven fabric was obtained in the same manner as in Example 3, except that the obtained web was treated with hot air at 130°C and a circulating air velocity of 1.0 m / s for 10 seconds using a hot air circulating dryer. In the obtained nonwoven fabric, heat bonding points were formed at the intersections of the heat-adhesive composite fibers.

[0101] [Example 13] A nonwoven fabric was obtained in the same manner as in Example 6, except that the non-heat-adhesive fiber was changed to a single-component rayon fiber with a fineness of 1.7 dtex (hollow ratio: 0%, biomass content: 100%). In the obtained nonwoven fabric, heat-adhesive points were formed at the intersections of the heat-adhesive composite fibers.

[0102] [Example 14] A nonwoven fabric was obtained in the same manner as in Example 1, except that the heat-adhesive composite fiber was changed to a concentric sheath-core type composite fiber (fineness 4.4 dtex, fiber length 51 mm, hollowness: 0%, biomass content: 0%) in which polyethylene terephthalate (melting point 250°C) was arranged in the core and copolymerized polyethylene terephthalate (melting point 163°C) in the sheath in a volume ratio of 50 / 50. In the obtained nonwoven fabric, heat-adhesive points were formed at the intersections of the heat-adhesive composite fibers.

[0103] [Example 15] A nonwoven fabric was obtained in the same manner as in Example 3, except that the heat-adhesive composite fiber was changed to a concentric sheath-core type composite fiber (fineness 4.4 dtex, fiber length 51 mm, hollowness: 0%, biomass content: 0%) in which polyethylene terephthalate (melting point 250°C) was arranged in the core and copolymerized polyethylene terephthalate (melting point 163°C) in the sheath in a volume ratio of 50 / 50. In the obtained nonwoven fabric, heat-adhesive points were formed at the intersections of the heat-adhesive composite fibers.

[0104] [Example 16] As a heat-adhesive composite fiber, a concentric sheath-core composite fiber with a zigzag mechanical crimp was prepared, with polylactic acid (melting point 170°C) in the core and low-melting point polylactic acid (melting point 120°C) in the sheath in a volume ratio of 50 / 50 (fineness 2.2 dtex, fiber length 45 mm, hollowness: 0%, biomass content: 100%). A water-repellent fiber treatment agent was applied to the surface of this fiber at a weight of 0.5% relative to the weight of the heat-adhesive composite fiber. As a non-heat-adhesive fiber, a fiber with a fineness of 1.7 dtex (hollowness: 0%, biomass content: 100%) made of a single rayon component was prepared. A hydrophilic fiber treatment agent was applied to the surface of this fiber at a weight of 0.5% relative to the weight of the heat-adhesive composite fiber. A web was prepared by mixing heat-adhesive composite fibers at a ratio of 70% by weight relative to the weight of the nonwoven fabric and non-heat-adhesive fibers at a ratio of 30% by weight relative to the weight of the nonwoven fabric, and then using the carding method. Next, the obtained web was introduced into a furnace filled with 160°C superheated steam for 10 seconds to obtain a nonwoven fabric. The wind speed of the superheated steam was 0.1 m / s or less. In the obtained nonwoven fabric, heat-bonding points were formed at the intersections of the heat-adhesive composite fibers.

[0105] Table 1 shows the physical properties of the nonwoven fabrics obtained in Examples 1 to 5, Table 2 shows the physical properties of the nonwoven fabrics obtained in Comparative Examples 1 to 3, Table 3 shows the physical properties of the nonwoven fabrics obtained in Examples 6 to 7 and Comparative Examples 4 to 5, Table 4 shows the physical properties of the nonwoven fabrics obtained in Examples 8 to 10 and Comparative Example 6, Table 5 shows the physical properties of the nonwoven fabrics obtained in Examples 11 to 12 and Comparative Example 7, and Table 6 shows the physical properties of the nonwoven fabrics obtained in Examples 13 to 16.

[0106]

[0107]

[0108]

[0109]

[0110]

[0111]

[0112] As can be seen from Tables 1 to 6, the nonwoven fabrics of Examples 1 to 16, which satisfy the constituent requirements of the present invention, received no "X" ratings in any of the following areas: heat retention, shape stability, flexibility, and compactness, and exhibited an excellent balance of these properties. However, the nonwoven fabrics of Comparative Examples 1 to 7, which do not satisfy the constituent requirements of the present invention, received an "X" rating in any of the following areas: heat retention, shape stability, flexibility, and compactness, and were not satisfactory in terms of the balance of properties. Specifically, Tables 1 and 2 show the physical properties of nonwoven fabrics with different types and fineness of non-heat-adhesive fibers. Comparative Example 1, which does not use non-heat-adhesive fibers, and Comparative Examples 2 and 3, which use non-heat-adhesive fibers with high fineness, were inferior in flexibility and compactness. Among these, the nonwoven fabric of Example 3 had excellent heat retention, the nonwoven fabric of Example 4 had a high biomass content and low environmental impact, and the nonwoven fabric of Example 5 was partially biodegradable and could reduce environmental problems such as microplastics. Table 3 shows the physical properties of nonwoven fabrics with varying mixing ratios of heat-adhesive composite fibers and non-heat-adhesive fibers. Comparative Example 4, with a high proportion of heat-adhesive composite fibers, exhibited poor flexibility and compactness, while Comparative Example 5, with a low proportion of heat-adhesive composite fibers, exhibited poor dimensional stability. Table 4 shows the physical properties of nonwoven fabrics with varying fineness of heat-adhesive composite fibers. Comparative Example 6, with a high fineness of heat-adhesive composite fibers, exhibited poor dimensional stability. Comparative Example 7 had a low specific volume and exhibited poor heat retention and compactness.

[0113] The nonwoven fabric of the present invention has an excellent balance of heat retention, shape stability, and flexibility, and can be made compact, making it suitable for use as padding for bedding such as comforters, mattresses, and pillows; padding for clothing such as down jackets and quilted fabrics; and padding for outdoor equipment such as sleeping bags and cooler bags. It can also be used for a variety of other items, including absorbent items such as diapers, napkins, and incontinence pads; sanitary materials such as masks, gowns, surgical gowns, and bandages; interior materials such as wall sheets, shoji paper, and flooring materials; household goods such as cover cloths, cleaning wipers, and garbage covers; toiletries 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 absorbents, abrasives, and ink tank absorbents; general medical materials; bedding materials; and nursing care products.

Claims

1. A nonwoven fabric in which heat-adhesive composite fibers with a fineness of 0.5 to 8.0 dtex are mixed in a ratio of 20 to 80% by weight relative to the weight of the nonwoven fabric, and non-heat-adhesive fibers with a fineness of 0.5 to 5.0 dtex relative to the weight of the nonwoven fabric, wherein the intersections of the heat-adhesive composite fibers are heat-bonded, and the specific volume of the nonwoven fabric is 150 to 400 cm³. ３ Nonwoven fabric, weighing / g.

2. The nonwoven fabric according to claim 1, wherein the heat-adhesive composite fiber is a sheath-core type composite fiber in which a polyolefin resin is arranged on the sheath side as a low-melting-point component and a polyester resin is arranged on the core side as a high-melting-point component.

3. The nonwoven fabric according to claim 2, wherein the biomass content of the nonwoven fabric is 10% or more.

4. The nonwoven fabric according to any one of claims 1 to 3, wherein the non-heat-adhesive fibers are polyethylene terephthalate fibers.

5. The nonwoven fabric according to any one of claims 1 to 3, wherein the non-heat-adhesive fibers are hollow polyethylene terephthalate fibers.

6. The nonwoven fabric according to any one of claims 1 to 3, wherein the non-heat-adhesive fibers are biodegradable polyethylene terephthalate fibers.

7. The nonwoven fabric according to any one of claims 1 to 3, wherein the non-heat-adhesive fiber is a polytrimethylene terephthalate fiber.

8. A sheet-like batting using the nonwoven fabric described in any one of claims 1 to 3.

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