JP6927299B2 - Non-woven - Google Patents

Description

The present invention relates to a non-woven fabric, and more particularly to a short-fiber non-woven fabric containing concentric core-sheath composite fibers and a laminated non-woven fabric containing the short-fiber non-woven fabric.

Conventionally, various non-woven fabrics are known. For example, Patent Document 1 describes a non-woven web A made of synthetic filaments having a core-sheath structure in which the melting point of the core component polymer is higher than the melting point of the sheath component polymer, and the melting point of the core component polymer is the melting point of the sheath component polymer. Disclosed is a non-woven fabric in which a non-woven web B made of synthetic long fibers having a core-sheath structure higher than the melting point of the sheath component polymer of the long fibers and higher than the melting point of the sheath component polymer of the long fibers is laminated and hot pressed. Has been done. Patent Document 2 describes a concentric core-sheath type heat-adhesive composite fiber in which the sheath component is a polyolefin and the core component is a polyester having a melting point higher than the melting point of the polyolefin by 20 ° C. or more, and the number of crimps (pieces / piece /). A heat-adhesive composite fiber having a crimp ratio of 12 to 19 (25 mm), a crimp ratio (%) of 10 to 20, and a crimp ratio / number of crimps of 0.8 to 1.1. The non-woven fabric used is disclosed. Patent Document 3 describes a non-woven fabric produced by an air-through method, which has a first layer and a second layer, and the density of the second layer is lower than the density of the first layer, and is at least the first. The fibers contained in the layer have a flat cross section, the long axis direction of the cross section is generally oriented in the plane direction of the non-woven fabric, and the surface on the first layer side has a rough surface. The average deviation SMD of the non-woven fabric is 2.5 μm or less, the average deviation MMD of the friction coefficient is less than 0.008, the linear LC of the compression characteristics of the non-woven fabric is 0.3 or less, and the flexural rigidity B is 0.03 cN. Nonwoven fabrics of cm ² / cm or less are disclosed.

Japanese Unexamined Patent Publication No. 4-316654 Japanese Unexamined Patent Publication No. 2003-41439 Japanese Unexamined Patent Publication No. 2006-23364

As described above, various non-woven fabrics have been conventionally known, and their uses are also diverse. For example, a non-woven fabric containing synthetic fibers made of a thermoplastic resin can be used as a sheet for absorbent articles such as disposable diapers and sanitary napkins. When a non-woven fabric is used for such an application, it is desired to have a good tactile sensation because the non-woven fabric is used so as to come into direct contact with the skin.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a non-woven fabric having a soft touch feeling and excellent touch.

The present invention includes the following inventions.
[1] A short-fiber nonwoven fabric containing concentric sheath-type composite fibers, wherein the sheath component of the concentric-sheath-sheath composite fiber contains linear low-density polyethylene, and the core component is the linear low-density. A non-woven fabric containing a thermoplastic resin having a melting point higher than that of polyethylene by 20 ° C. or higher.
[2] The non-woven fabric according to [1], wherein the concentric core-sheath type composite fiber has a crimp number of 10 to 30 fibers / 25 mm and a crimp rate of 10% to 30%.
[3] A laminated non-woven fabric comprising the non-woven fabric according to [1] or [2] as a first non-woven fabric layer, and further having a second non-woven fabric layer made of a short fiber non-woven fabric.
[4] The laminated non-woven fabric according to [3], wherein the apparent density of the first non-woven fabric layer is larger than the apparent density of the second non-woven fabric layer.
[5] The laminated non-woven fabric according to [3] or [4], wherein the first non-woven fabric layer and the second non-woven fabric layer have a basis weight of 10 to 60 g / m ^{2, respectively.}

Since the non-woven fabric of the present invention is composed of a concentric core sheath type composite fiber containing a linear low-density polyethylene as a sheath component, it has a soft touch feeling and is excellent in touch.

The non-woven fabric of the present invention is a short fiber non-woven fabric containing concentric core-sheath composite fibers, in which the sheath component of the concentric core-sheath composite fiber contains linear low-density polyethylene and the core component is the linear chain. It contains a thermoplastic resin having a melting point of 20 ° C. or higher higher than the melting point of low-density polyethylene. Since the non-woven fabric of the present invention is composed of a concentric core sheath type composite fiber containing a linear low-density polyethylene as a sheath component, it has a soft touch feeling and is excellent in touch. Therefore, the non-woven fabric of the present invention can be suitably used as a disposable diaper, a member on the skin contact side of an absorbent article such as a sanitary product, a medical non-woven fabric product such as drape or gauze, a wet tissue or a wet towel. Hereinafter, the nonwoven fabric of the present invention will be described in detail.

The linear low-density polyethylene, which constitutes the sheath component of the core-sheath type composite fiber, gives a soft touch to the fiber surface and acts to give a good touch when made into a non-woven fabric. Linear low density polyethylene constituting the sheath component of the core-sheath type composite fiber, an ethylene group (-CH ₂ -CH ₂ -) is not particularly limited as long as it is a linear (co) polymer containing as a repeating unit However, a copolymer of ethylene and an α-olefin having 3 or more carbon atoms is preferable because it is easy to increase the flexibility of the fiber. Examples of α-olefins having 3 or more carbon atoms include propylene, butene-1, penten-1, 4-methylpentene-1, hexene-1, 4-methylhexene-1, heptene-1, octene-1, and nonene-1. , Decene-1, Dodecene-1, and the like. Only one kind of these α-olefins may be contained, or two or more kinds thereof may be contained. The number of carbon atoms of the α-olefin is preferably 4 or more, preferably 12 or less, more preferably 8 or less, and even more preferably 6 or less. Among them, as the α-olefin, propylene, butene-1, 4-methylpentene-1, hexene-1, 4-methylhexene-1, octene-1 are preferable, butene-1, butene-1 and hexene-1 are more preferable.

The content of α-olefin in the linear low-density polyethylene is preferably 1 mol% or more, more preferably 2 mol% or more, preferably 10 mol% or less, and more preferably 5 mol% or less. By setting the content of α-olefin in the linear low-density polyethylene to 1 mol% or more, it becomes easy to increase the flexibility of the fiber. On the other hand, when the content of α-olefin is large, the crystallinity deteriorates and the fibers are easily fused to each other at the time of fiberization. Therefore, the content of α-olefin in the linear low-density polyethylene is 10 mol. % Or less is preferable.

The density of the linear low density polyethylene (true density) is preferably from 0.900 g / cm ³ or more, more preferably 0.905 g / cm ³ or more, more preferably 0.910 g / cm ³ or more, 0.913 g / cm ³ or even more preferably, also preferably from 0.945 g / cm ³ or less, more preferably 0.940 g / cm ³ or less, more preferably 0.938 g / cm ³ or less. When the density of the linear low-density polyethylene is 0.900 g / cm ³ or more, it becomes easy to impart bulkiness and bulk recovery property when the non-woven fabric is used. Further, in the production of non-woven fabric, the high-speed card property is excellent. When the density of the linear low-density polyethylene is 0.945 g / cm ³ or less, it is easy to enhance the surface tactile sensation when the non-woven fabric is made, and it is easy to secure the flexibility in the thickness direction of the non-woven fabric.

The melting point of the linear low-density polyethylene is preferably 110 ° C. or higher and 128 ° C. or lower. When the melting point of the linear low-density polyethylene is 110 ° C. or higher, it becomes easy to improve the surface feel of the non-woven fabric even when the non-woven fabric is produced by thermal adhesion at a high temperature. Further, in the production of a non-woven fabric, the high-speed card property is excellent, and the obtained non-woven fabric tends to have good uniformity (or good texture). When the melting point of the linear low-density polyethylene is 128 ° C. or lower, it becomes easy to obtain a non-woven fabric having a strength sufficient for practical use even when the non-woven fabric is manufactured by thermal adhesion at a low temperature.

The melt flow rate (MFR) of the linear low-density polyethylene is preferably 1 g / 10 min or more, more preferably 2 g / 10 min or more, further preferably 3 g / 10 min or more, further preferably 5 g / 10 min or more, and 60 g / 10 min or more. It is preferably 10 min or less, more preferably 40 g / 10 min or less, further preferably 35 g / 10 min or less, and even more preferably 30 g / 10 min or less. If the MFR of the linear low-density polyethylene is 1 g / 10 min or more, the spinnability is good, and if the MFR of the linear low-density polyethylene is 60 g / 10 min or less, the fibers are fused to each other during fiber production. It is less likely to occur and the formation of single fibers becomes easier. MFR is measured according to JIS K 6922-1 (1997) (condition: 190 ° C., load 21.18 N (2.16 kgf)).

The ratio Mw / Mn of the weight average molecular weight (Mw) to the number average molecular weight (Mn) in the linear low-density polyethylene is preferably 5.0 or less, more preferably 4.0 or less, still more preferably. It is 3.5 or less. The lower limit of Mw / Mn of the linear low-density polyethylene is not particularly limited, but is usually 1.5 or more, may be 2.0 or more, or may be 2.5 or more.

The flexural modulus of the linear low-density polyethylene is preferably 65 MPa or more, more preferably 120 MPa or more, further preferably 180 MPa or more, further 250 MPa or more, from the viewpoint of enhancing the surface tactile sensation of the obtained non-woven fabric and ensuring bulkiness. More preferably, 850 MPa or less is preferable, 750 MPa or less is more preferable, 700 MPa or less is further preferable, and 650 MPa or less is even more preferable. The flexural modulus is measured according to JIS K 7171 (2008). When the flexural modulus of the linear low-density polyethylene is 65 MPa or more, it becomes easy to impart bulkiness and elasticity to the obtained non-woven fabric. On the other hand, when the flexural modulus of the linear low-density polyethylene is 850 MPa or less, the surface texture of the obtained non-woven fabric can be easily made flexible.

The durometer hardness (HDD) of the linear low-density polyethylene is preferably 45 or more, more preferably 48 or more, further preferably 50 or more, still preferably 75 or less, more preferably 70 or less, still more preferably 65 or less. 62 or less is even more preferable. Durometer hardness (HDD) is measured using a type D durometer and is measured in accordance with JIS K 7215 (1986). When the durometer hardness (HDD) of the linear low-density polyethylene is 45 or more, it becomes easy to impart bulkiness or bulk recovery to the obtained non-woven fabric. In addition, it becomes easier to secure the passage of cards during fiber production. When the durometer hardness (HDD) of the linear low-density polyethylene is 75 or less, the surface texture of the obtained non-woven fabric can be easily made flexible.

The linear low-density polyethylene can be easily obtained, for example, by (co) polymerizing a monomer component containing ethylene using a metallocene catalyst or a Ziegler-Natta catalyst. Preferably, the linear low density polyethylene is produced by copolymerizing ethylene with an α-olefin.

The sheath component of the core-sheath type composite fiber may contain a polymer component other than linear low-density polyethylene. The sheath component preferably contains linear low-density polyethylene as a main component, and specifically, the content ratio of the linear low-density polyethylene is preferably 50% by mass or more in 100% by mass of the sheath component. 60% by mass or more is more preferable, and 75% by mass or more is further preferable. The sheath component may contain only linear low-density polyethylene as a polymer component.

Examples of the polymer component other than the linear low-density polyethylene that can be contained in the sheath component include high-density polyethylene, branched low-density polyethylene, polypropylene, polybutene, polybutylene, polymethylpentene, polybutadiene, and copolymers thereof. Polyethylene resins; polyester resins such as polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polyethylene naphthalate, polylactic acid, polybutylene succinate, and copolymers thereof; nylon 66, nylon 12, nylon 6, etc. Polyamitone resin; Acrylic resin such as methyl poly (meth) acrylate, ethyl poly (meth) acrylate, ethylene- (meth) methyl acrylate copolymer, ethylene- (meth) acrylate copolymer; polyacetic acid Vinyl ester-based resins such as vinyl and ethylene-vinyl acetate copolymers; vinyl alcohol-based resins such as polyvinyl alcohol and ethylene-vinyl alcohol copolymers; polycarbonate; polyacetal; polystyrene; cycloolefin-based resins and the like can be mentioned. Only one kind of these resins may be contained, or two or more kinds thereof may be contained. Among them, the sheath component preferably further contains branched low-density polyethylene, which can increase the flexibility of the non-woven fabric in the thickness direction. Further, since the sheath component contains branched low-density polyethylene, the non-woven fabric can be processed in a wide temperature range, and a non-woven fabric having uniform flexibility can be obtained, for example, when the non-woven fabric is formed by thermal adhesion. Becomes easier.

The density (true density) of the branched low-density polyethylene is preferably ^{0.910 g / cm 3 to} 0.930 g / cm ^3. Further, the branched low-density polyethylene preferably has a melting point lower than that of the linear low-density polyethylene by 5 ° C. or higher, and more preferably 10 ° C. or higher.

The melt flow rate (MFR) of the branched low-density polyethylene is preferably 1 g / 10 min or more, more preferably 3 g / 10 min or more, further preferably 5 g / 10 min or more, still more preferably 10 g / 10 min or more, in consideration of spinnability. It is preferable, 60 g / 10 min or less is preferable, and 50 g / 10 min or less is more preferable. The method for measuring MFR is as described above.

The combined content ratio of the linear low-density polyethylene and the branched low-density polyethylene in the sheath component of the core-sheath type composite fiber is preferably 70% by mass or more, more preferably 80% by mass or more, based on 100% by mass of the sheath component. It is preferable, and 90% by mass or more is more preferable. Further, the ratio of the linear low-density polyethylene is preferably 75% by mass or more, more preferably 80% by mass or more, and 100% by mass or less in the total 100% by mass of the linear low-density polyethylene and the branched low-density polyethylene. Is preferable, 95% by mass or less is more preferable, and 90% by mass or less is further preferable.

The sheath component is an additive other than the polymer component, for example, an antistatic agent, a pigment, a matting agent, a heat stabilizer, a light stabilizer, a flame retardant, an antibacterial agent, a lubricant, a plasticizer, a softener, an antioxidant, an ultraviolet ray. Additives such as absorbents and crystal nucleating agents may be included. These additives are preferably contained in the sheath component in an amount of 10% by mass or less based on 100% by mass of the sheath component.

The core component of the core-sheath type composite fiber is composed of an arbitrary thermoplastic resin. The core component contains at least a thermoplastic resin having a melting point higher than the melting point of the linear low-density polyethylene by 20 ° C. or more, and the melting point of the thermoplastic resin is preferably higher than the melting point of the linear low-density polyethylene. Is also 30 ° C. or higher, more preferably 40 ° C. or higher, and even more preferably 50 ° C. or higher. The core component acts to enhance the bulkiness and bulk recovery of the non-woven fabric.

The thermoplastic resins constituting the core component include polyolefin resins such as polypropylene, polybutene, polybutylene, polymethylpentene, polybutadiene, and copolymers thereof; polyethylene, polypropylene, polybutene, polybutylene, polymethylpentene, polybutadiene, and Polypropylene-based resins such as these copolymers; polyamide-based resins such as nylon 66, nylon 12, and nylon 6; methyl poly (meth) acrylate, ethyl poly (meth) acrylate, and methyl ethylene- (meth) acrylate. Acrylic resins such as polymers and ethylene- (meth) acrylic acid copolymers; vinyl ester resins such as polypropylene and ethylene-vinyl acetate copolymers; vinyls such as polyvinyl alcohol and ethylene-vinyl alcohol copolymers. Alcohol-based resins; polypropylene; polyacetal; polystyrene; cycloolefin-based resins and the like can be mentioned. These may contain only one kind, or may contain two or more kinds. Among them, polyolefin-based resins, polyester-based resins, and polyamide-based resins are preferable, and polyester-based resins are more preferable, from the viewpoint of uniformity of the non-woven fabric and productivity of the non-woven fabric. Among the polyester resins, polyethylene terephthalate and polybutylene terephthalate are preferable, and polyethylene terephthalate is more preferable.

The core component preferably contains the thermoplastic resin described above as a main component, and specifically, the content ratio of the thermoplastic resin (particularly polyester resin) is 50% by mass or more in 100% by mass of the core component. Is preferable, 60% by mass or more is more preferable, and 75% by mass or more is further preferable. The core component may contain only the thermoplastic resin described above as a polymer component, and may contain, for example, only polyester.

The core component includes additives other than polymer components, such as antistatic agents, pigments, matting agents, heat stabilizers, light stabilizers, flame retardants, antibacterial agents, lubricants, plasticizers, fabric softeners, antioxidants, and ultraviolet rays. Additives such as absorbents and crystal nucleating agents may be included. These additives are preferably contained in the core component in an amount of 10% by mass or less based on 100% by mass of the core component.

The composite ratio (mass ratio) of the core component / sheath component in the core-sheath type composite fiber is preferably 30/70 or more, more preferably 35/65 or more, further preferably 40/60 or more, and preferably 80/20 or less. , 70/30 or less is more preferable, and 60/40 or less is further preferable. When the composite ratio of the core component / sheath component is in such a range, the strength and flexibility of the obtained non-woven fabric can be easily ensured, and the bulk recovery property can be easily enhanced.

The core-sheath type composite fiber is formed so that the core component and the sheath component are substantially concentric. That is, in the fiber cross section, the center of gravity of the core component is formed so as to substantially coincide with the center of gravity of the fiber. By using the concentric core-sheath type composite fiber, for example, by mechanically applying crimping after spinning, the core-sheath type composite fiber is arbitrarily crimped as compared with the case where the eccentric core-sheath type composite fiber is used. (Number of crimps, crimp rate, etc.) can be easily assigned. In addition, the deterioration of the formation that occurs when the eccentric core-sheath type composite fiber is used, such as when heat-treating during non-woven fabric processing, is observed, and the deterioration of the formation is almost observed when the concentric core-sheath type composite fiber is used. However, the effect of improving the feel of the obtained non-woven fabric can be obtained.

The concentric sheath type composite fiber preferably has crimping. If the concentric core-sheath type composite fiber has crimping, the bulkiness and cushioning property of the obtained non-woven fabric can be enhanced. The number of crimps of the concentric sheath type composite fiber is preferably 10 pieces / 25 mm or more, more preferably 12 pieces / 25 mm or more, preferably 30 pieces / 25 mm or less, more preferably 25 pieces / 25 mm or less, and 22 Pieces / 25 mm or less are more preferable. The crimp ratio of the concentric sheath type composite fiber is preferably 10% or more, more preferably 12% or more, more preferably 30% or less, more preferably 25% or less, still more preferably 20% or less. If the concentric core-sheath type composite fiber has such a number of crimps and a crimp ratio, it becomes easy to enhance the bulkiness and cushioning property of the obtained non-woven fabric. The number of crimps and the crimp rate of the concentric sheath type composite fiber are measured according to JIS L 1015 (2010).

The concentric core-sheath type composite fiber preferably has a crimp ratio / crimp number ratio (unit:% / (pieces / 25 mm)) of 0.4 or more, more preferably 0.5 or more, and 0. 8 or more is more preferable, 1.2 or less is preferable, 1.1 or less is more preferable, and 1.0 or less is further preferable. When the ratio of the crimp ratio / the number of crimps is within such a range, the crimp is difficult to stretch, and the concentric core-sheath type composite fiber has a crimp of an appropriate size. Further, when such a crimp fiber is used, the productivity at the time of producing the non-woven fabric is excellent, and the bulkiness and elasticity of the obtained non-woven fabric can be easily increased.

The fineness of the concentric sheath type composite fiber is not particularly limited. The fineness of the concentric sheath type composite fiber is, for example, preferably 1.1 dtex or more, more preferably 1.5 dtex or more, preferably 15 dtex or less, more preferably 10 dtex or less, still more preferably 5 dtex or less.

The fiber length of the concentric core-sheath type composite fiber as a short fiber is, for example, preferably 1 mm or more, more preferably 3 mm or more, further preferably 5 mm or more, further preferably 100 mm or less, more preferably 72 mm or less, and further preferably 64 mm or less. preferable. The preferable range of the fiber length of the short fibers also depends on the web forming method in the production of the non-woven fabric. For example, when forming the web using a card machine, the fiber length of the short fibers may be 10 mm or more, and may be 20 mm. It may be more than or equal to, and may be 30 mm or more. When forming the web using an air raid machine, the fiber length of the short fibers may be 50 mm or less.

The non-woven fabric of the present invention may contain fibers other than the concentric core-sheath type composite fiber. Other fibers include natural fibers such as cotton, silk, wool, hemp, and pulp; recycled fibers such as rayon and cupra; synthesis of polyolefin fibers, polyester fibers, acrylic fibers, polyamide fibers, polyurethane fibers, etc. Fiber is mentioned. Only one of these other fibers may be contained in the non-woven fabric, or two or more of these other fibers may be contained in the non-woven fabric, and can be appropriately selected depending on the use of the non-woven fabric. The non-woven fabric of the present invention preferably contains the concentric core-sheath type composite fiber described above as a main component, and specifically, 50% by mass of the concentric core-sheath type composite fiber in 100% by mass of the non-woven fabric. It is preferably contained in the above ratio, more preferably 70% by mass or more, still more preferably 80% by mass or more. The non-woven fabric may be composed only of the above-mentioned concentric core-sheath type composite fibers.

The texture of the non-woven fabric containing the concentric core-sheath composite fiber may be appropriately set according to the use of the non-woven fabric. For example, 10 g / m ² or more is preferable, 14 g / m ² or more is more preferable, and 18 g / m is preferable. ² or more is further preferable, 60 g / m ² or less is preferable, 50 g / m ² or less is more preferable, 45 g / m ² or less is further preferable, and 40 g / m ² or less is even more preferable.

The short fiber nonwoven fabric containing the concentric sheath type composite fiber of the present invention can be produced, for example, as follows.

First, a linear low-density polyethylene as a sheath component and a thermoplastic resin as a core component are used, and these two components are melt-spun using a concentric composite nozzle, and the concentric core-sheath composite unstretched. Get the fiber. The spinning temperature of the sheath component at this time is preferably adjusted in the range of, for example, 200 ° C. to 300 ° C., and the spinning temperature of the core component is preferably adjusted in the range of, for example, 240 ° C. to 350 ° C. The take-up speed of the undrawn fibers may be adjusted in the range of, for example, 100 m / min to 1500 m / min.

Next, the undrawn fibers are stretched. The draw ratio at this time is, for example, preferably 1.2 times or more, more preferably 1.5 times or more, further preferably 1.8 times or more, still more preferably 2.0 times or more, and 5.0 times or less. Is preferable, 4.0 times or less is more preferable, and 3.8 times or less is further preferable.

The drawn fibers thus obtained are preferably heat-treated. The heat treatment can be performed using, for example, a heating medium or a heating device having a temperature of about 30 ° C. to 120 ° C. Examples of the heat treatment method include a heating roller and steam treatment. The heat-treated fibers can be crimped with a crimper. At this time, the crimping adjustment is performed by the nip pressure and the stuffing pressure, but the fiber temperature immediately before the crimper is set to about 30 ° C. to 70 ° C. from the viewpoint of preventing the fiber from breaking while appropriately applying the crimping to the fiber. The temperature of the crimper roller is preferably about 30 ° C. to 90 ° C. The crimped fibers are subjected to hot air heat treatment in a non-tensioned state and dried. By cooling and cutting the fibers heat-treated with hot air, short fibers of concentric core-sheath type composite fibers to which crimping is imparted can be obtained. The composite fiber thus obtained has a core component and a sheath component having a concentric cross section and is sufficiently crimped, so that it is excellent in bulkiness and cushioning property, and gives a non-woven fabric having a uniform texture. It becomes a thing. In addition, web formation during the production of the non-woven fabric becomes easy.

The method for forming the short fibers of the concentric core-sheath type composite fiber into a web is not particularly limited, and for example, a card web method such as parallel web, semi-random web, random web, cross web, and Chris cross web; airlaid web method; wet A papermaking web method and the like can be mentioned. When forming the fiber web, the short fibers of the concentric core-sheath type composite fiber are mixed with other fibers (for example, synthetic fibers such as polyolefin fibers and polyester fibers, and natural or regenerated fibers such as rayon and cotton). The web may be formed.

It is preferable to adopt a thermal bond (thermal bonding) as the interfiber bonding method, and therefore, the non-woven fabric of the present invention is preferably a thermal bond non-woven fabric. As the thermal bond method, an air-through method or a heat roll method can be adopted. The air-through method is a method in which a fiber web such as a card web is placed on a breathable net or a drum and hot air is blown to heat-fuse the intersections of the constituent fibers to form a non-woven fabric. In the heat roll method, a fiber web such as a card web is sandwiched between an embossed roll and a smoothing roll heated to a predetermined temperature, or between a pair of smoothing rolls, thereby heat-sealing the intersections of the constituent fibers. It is a method of making a non-woven fabric. Of these methods, the air-through method is preferable because it is easy to obtain a non-woven fabric having excellent bulkiness and cushioning properties. Therefore, the non-woven fabric of the present invention is preferably an air-through non-woven fabric. In the case of the non-woven fabric of the present invention, it is preferable to heat the composite fiber to a temperature equal to or higher than the melting point of the linear low-density polyethylene of the sheath component to melt the sheath component and bond the composite fibers to each other. As the temperature, for example, 125 ° C. or higher is preferable, 128 ° C. or higher is more preferable, 150 ° C. or lower is preferable, and 145 ° C. or lower is more preferable.

The present invention also provides a laminated non-woven fabric that essentially contains a short-fiber non-woven fabric containing the concentric sheath-type composite fibers described above. The laminated non-woven fabric of the present invention has a short-fiber non-woven fabric containing the above-mentioned concentric core-sheath type composite fiber as a first non-woven fabric layer, and further has a second non-woven fabric layer made of a short-fiber non-woven fabric. The second non-woven fabric layer may be the same as or different from the first non-woven fabric layer. In the laminated non-woven fabric, it is preferable that the first non-woven fabric layer is mainly a contact surface with the skin.

The type of fiber constituting the second non-woven fabric layer is not particularly limited, and natural fibers such as cotton, silk, wool, linen and pulp; recycled fibers such as rayon and cupra; polyolefin fibers, polyester fibers, acrylic fibers, etc. Examples thereof include synthetic fibers such as polyamide fibers and polyurethane fibers. These fibers may contain only one type, or may contain two or more types. The fibers constituting the second non-woven fabric layer are not limited to fibers composed of a single component, and may be composite fibers (concentric or eccentric core-sheath type composite fibers, side-by-side type composite fibers, etc.). Examples of the resin constituting each component of the composite fiber include a thermoplastic resin capable of constituting the core component or the sheath component of the concentric core-sheath type composite fiber described above. The fibers constituting the second non-woven fabric layer may or may not have crimping.

The method for forming the fiber web of the second non-woven fabric layer is not particularly limited, and the web forming method described above can be adopted. The interfiber bonding method is also not particularly limited, and examples thereof include thermal bonds, chemical bonds, and spunlaces. The second non-woven fabric layer is preferably a thermal-bonded non-woven fabric from the viewpoint of increasing the bulkiness of the second non-woven fabric layer and easily ensuring liquid permeability.

The second non-woven fabric layer is preferably a short fiber non-woven fabric containing an eccentric core-sheath type composite fiber or a hollow core-sheath type composite fiber. If the second non-woven fabric layer is configured in this way, it becomes easy to increase the bulkiness and cushioning property of the second non-woven fabric layer. When the second non-woven fabric layer is composed of an eccentric core-sheath type composite fiber, the eccentric core-sheath type composite fiber contains, for example, high-density polyethylene as a sheath component and has a core component of 20 ° C. or higher as compared with high-density polyethylene. It preferably contains a thermoplastic resin having a high melting point.

When the fibers constituting the second non-woven fabric layer are synthetic fibers or composite fibers, the fibers include antistatic agents, pigments, matting agents, heat stabilizers, light stabilizers, flame retardants, and antibacterial agents in addition to the polymer components. Additives such as agents, lubricants, plasticizers, fabric softeners, antioxidants, UV absorbers, crystal nucleating agents and the like may be included. These additives are preferably contained in the fiber in an amount of 10% by mass or less based on 100% by mass of the fiber.

The basis weight of the second non-woven fabric layer may be appropriately set according to the use of the laminated non-woven fabric. For example, 10 g / m ² or more is preferable, 14 g / m ² or more is more preferable, 18 g / m ² or more is further preferable, and more. 60 g / m ² or less is preferable, 50 g / m ² or less is more preferable, 40 g / m ² or less is further preferable, and 35 g / m ² or less is even more preferable.

The basis weight ratio of the first non-woven fabric layer to the second non-woven fabric layer is preferably 20/80 or more, more preferably 30/70 or more, further preferably 35/65 or more, and preferably 70/30 or less, 60 /. 40 or less is more preferable, and 55/45 or less is further preferable. By adjusting the basis weight of the first non-woven fabric layer and the second non-woven fabric layer in this way, it becomes easy to enhance the bulkiness and cushioning property of the laminated non-woven fabric while making the tactile sensation on the first non-woven fabric layer side of the laminated non-woven fabric flexible.

The laminated non-woven fabric preferably has an apparent density of the first non-woven fabric layer higher than the apparent density of the second non-woven fabric layer. When the laminated non-woven fabric is configured in this way, when the laminated non-woven fabric absorbs the liquid, the liquid is rapidly transferred to the second non-woven fabric layer, and the surface on the first non-woven fabric layer side is kept relatively dry. 2 It becomes easy to suppress liquid return (rewet) from the non-woven fabric layer to the first non-woven fabric layer. The apparent density of each non-woven fabric layer can be obtained by dividing the basis weight by the thickness. The thickness is measured using a thickness measuring device in accordance with JIS L 1913 (2010).

The first non-woven fabric layer preferably exhibits hydrophilicity. It is preferable that the second non-woven fabric layer also exhibits hydrophilicity. For example, by treating the constituent fibers of the first non-woven fabric layer and the second non-woven fabric layer with a hydrophilic agent, or by forming the first non-woven fabric layer and the second non-woven fabric layer from hydrophilic fibers, the first non-woven fabric layer and the second non-woven fabric are used. The layer can be formed hydrophilic. As the hydrophilic agent, a surfactant or the like can be used.

The first non-woven fabric layer and the second non-woven fabric layer may be formed so that the degree of hydrophilicity is different from each other. For example, the first non-woven fabric layer is preferably formed with a lower degree of hydrophilicity than the second non-woven fabric layer. Alternatively, the first non-woven layer is formed hydrophilic by treating the hydrophobic fibers with a hydrophilic agent, and the second non-woven layer is composed of hydrophilic fibers or the hydrophobic fibers are treated with a hydrophilic agent. By doing so, it is preferable to form hydrophilic. As a result, when the laminated non-woven fabric absorbs the liquid, the liquid is rapidly transferred to the second non-woven fabric layer, the surface on the first non-woven fabric layer side is kept relatively dry, and the second non-woven fabric layer is transferred to the first non-woven fabric layer. It becomes easier to suppress the liquid return.

It is also preferable that the constituent fibers of the first nonwoven fabric layer are formed so that the degree of hydrophilicity is more likely to decrease upon contact with water than the constituent fibers of the second nonwoven fabric layer. By adjusting the degree of hydrophilicity of the constituent fibers of each layer in this way, the surface on the side of the first non-woven fabric layer can be kept relatively dry, and the amount of liquid returning from the second non-woven fabric layer to the first non-woven fabric layer can be reduced. can. At this time, it is preferable to adjust the degree of hydrophilicity of the constituent fibers of each layer as follows. Regarding the first non-woven layer, it is preferable to use a hydrophilic agent containing a nonionic surfactant, specifically, with water such as polyoxyethylene alkyl ether, polyoxyethylene fatty acid ester, and sorbitan fatty acid ester. A substance that relatively easily separates from the fiber surface upon contact is used as a hydrophilic agent, and this is applied to the surface of the hydrophobic fiber. Regarding the second non-woven layer, fibers such as polyglycerin fatty acid ester, polyether-polyester block copolymer, polyether-modified silicone, and fatty acid ester of ethylene oxide-added polyhydric alcohol as hydrophilic agents even when in contact with water. A substance that does not easily separate from the surface is used as a hydrophilic agent, and this is applied to the surface of the hydrophobic fiber, or the hydrophilic agent is kneaded into the fiber in advance. Alternatively, hydrophilic fibers may be used as the constituent fibers of the second non-woven fabric layer, or hydrophilic fibers may be mixed.

In the first non-woven fabric layer or the second non-woven fabric layer, cotton fibers or rayon fibers may be blended in a ratio of about 0.1% by mass to 5% by mass in each layer for the purpose of adjusting the hydrophilicity of these layers. .. Further, for the purpose of enhancing the concealing property of the non-woven fabric, a pigment such as titanium oxide may be blended in the constituent fibers of the first non-woven fabric layer and the second non-woven fabric layer at a ratio of 3% by mass or less.

The first non-woven fabric layer and the second non-woven fabric layer are preferably bonded to each other by thermal adhesion. Specifically, it is preferable that the constituent fibers of the first non-woven fabric layer and the constituent fibers of the second non-woven fabric layer are bonded to each other at contact points or intersections by thermal adhesion. When the first non-woven fabric layer and the second non-woven fabric layer are joined in this way, it becomes easy to improve the liquid permeability from the first non-woven fabric layer to the second non-woven fabric layer while forming the laminated non-woven fabric in a bulky manner. .. As a method of heat-bonding the first non-woven fabric layer and the second non-woven fabric layer, a heat treatment device such as a hot air penetration type heat treatment machine, a hot air blowing type heat treatment machine, or an infrared heat treatment machine is used, and the first non-woven fabric layer and the second non-woven fabric are used. Examples thereof include a method of blowing hot air or heating the atmosphere in a state where the layers are laminated.

The basis weight of the laminated non-woven fabric may be appropriately selected depending on the intended use of the non-woven fabric. For example, 20 g / m ² or more is preferable, 28 g / m ² or more is more preferable, 35 g / m ² or more is further preferable, and 80 g / m ² or less is more preferable. Is preferable, 70 g / m ² or less is more preferable, and 65 g / m ² or less is further preferable. The basis weight of the first non-woven fabric layer is preferably 20% or more, more preferably 30% or more, further preferably 40% or more, still more preferably 75% or less, and more preferably 70% or less of the basis weight of the laminated non-woven fabric. It is preferable, and 65% or less is more preferable.

In one form, the laminated non-woven fabric may be composed of only the first non-woven fabric layer and the second non-woven fabric layer. In another embodiment, the laminated non-woven fabric may have a structure in which the first non-woven fabric layer is laminated on both surfaces of the second non-woven fabric layer. In still another embodiment, the laminated nonwoven fabric may have a structure in which two or more identical or different second nonwoven fabric layers are laminated.

The non-woven fabric and the laminated non-woven fabric of the present invention have a soft touch feeling and are excellent in touch. Further, it has a bulky and fluffy feel when the surface of the non-woven fabric is pressed, and can impart appropriate cushioning property and bulk recovery property, so that it can be suitably used for applications that come into contact with the skin. The non-woven fabrics and laminated non-woven fabrics of the present invention are absorbent articles such as disposable diapers, sanitary napkins, panty liners, incontinence pads, interlipinal pads, breast milk pads, disposable diapers for animals; drapes, gauze, bandages, wound surface protection. Medical non-woven fabric products such as sheets and pads for hemorrhoids; Interpersonal wiping sheets such as wet tissues, wet towels, makeup removers, antiperspirant sheets, and wipes; face masks, cold / warm pads, used in contact with the skin It can be used as a base cloth for patches such as heating appliances (for example, disposable cairo). The non-woven fabric and laminated non-woven fabric of the present invention can be particularly preferably applied to a liquid-permeable surface sheet (top sheet) used for an absorbent article.

The present application claims the benefit of priority under Japanese Patent Application No. 2017-11148 filed on June 5, 2017. The entire contents of the specification of Japanese Patent Application No. 2017-11148 filed on June 5, 2017 are incorporated herein by reference.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited by the following examples as well as the present invention, and appropriate modifications are made to the extent that it can be adapted to the gist of the above and the following. It is also possible to carry out, all of which are within the technical scope of the invention.

(1) Manufacture of core-sheath type composite fiber (1-1) Core-sheath type composite fiber A
Linear low-density polyethylene "Niporon (registered trademark) -LM70" (manufactured by Toso Co., Ltd., MFR 20 g / 10 min, density 0.936 g / cm ³ , melting point 124 ° C.) is used as the sheath component, and polyethylene is used as the core component. Using terephthalate (melting point 256 ° C., ultimate viscosity value (IVp) 0.64), using a concentric composite nozzle for these two components, the composite ratio (mass ratio) of the core component / sheath component is set to 60/40. , A single-hole discharge rate of 0.60 g / min and a take-up speed of 1100 m / min were melt-extruded to obtain a filament having a fineness of 5.5 dtex. The obtained spun filament was stretched 2.7 times in a bathtub at 70 ° C. to obtain a drawn filament having a fineness of 2.6 dtex. A hydrophilic oil agent is applied to the drawn filament, mechanical crimping is applied with a stuffing box type crimper, heat treatment is performed with a hot air blowing device at 100 ° C., the filament is cut to a fiber length of 44 mm, and a concentric core sheath type is applied. Short fibers of composite fibers were obtained. The number of crimps of the obtained fibers was 18/25 mm, and the crimp ratio was 15%. Table 1 summarizes the fiber production conditions and properties.

(1-2) Core-sheath type composite fiber B
Manufactured under the same conditions as the core-sheath type composite fiber A except that the composite ratio (mass ratio) of the core component / sheath component was 50/50, the fineness was 2.7 dtex, the fiber length was 44 mm, and the number of crimps was 17/25 mm. , A concentric core-sheath type composite fiber B having a crimp ratio of 12% was obtained.

(1-3) Core-sheath type composite fiber C
20% by mass of the sheath component is high-density polyethylene "Niporon Hard (registered trademark)" (manufactured by Toso Co., Ltd., MFR 20g / 10min, density 0.964g / cm ³ , melting point 131 ° C), and the remaining 80% by mass is linear low density. Manufactured under the same conditions as the concentric core-sheath composite fiber A except that it is composed of polyethylene "Niporon (registered trademark) -LM70", fineness 2.6 dtex, fiber length 44 mm, number of crimps 17/25 mm, winding. A concentric core-sheath type composite fiber C having a shrinkage ratio of 16% was obtained.

(1-4) Core-sheath type composite fiber D
Manufactured under the same conditions as core-sheath type composite fiber A, except that it was spun using an eccentric cross-section type composite nozzle with the core offset from the center, fineness 2.6 dtex, fiber length 44 mm, number of crimps 18/25 mm, An eccentric core sheath type composite fiber D having a crimp ratio of 16% was obtained.

(1-5) Core-sheath type composite fiber E
Manufactured under the same conditions as core-sheath type composite fiber A except that high-density polyethylene "Niporon Hard (registered trademark)" was used as the sheath component, fineness 2.7 dtex, fiber length 38 mm, number of crimps 20/25 mm, winding. A concentric core-sheath type composite fiber E having a shrinkage ratio of 14% was obtained.

(1-6) Core-sheath type composite fiber F
It is manufactured under the same conditions as the core-sheath type composite fiber E except that it is spun with a single-hole discharge rate of 0.65 g / min using an eccentric cross-section type composite nozzle with the core offset from the center. An eccentric core-sheath type composite fiber F having a length of 43 mm, a number of crimps of 18/25 mm, and a crimp ratio of 16% was obtained.

(1-7) Core-sheath type composite fiber G
Manufactured under the same conditions as the core-sheath composite fiber F except that the single-hole discharge rate was 0.55 g / min, the take-up speed was 1500 m / min, and the draw ratio was 2.2 times, the fineness was 2.3 dtex, and the fiber length. An eccentric core-sheath type composite fiber G having a crimp rate of 44 mm, a number of crimps of 19/25 mm, and a crimp rate of 16% was produced.

(2) Production of Nonwoven Fabric The first layer fiber web having the basis weights shown in Table 2 using the core-sheath type composite fibers A to E, and the first layer fiber web having the basis weight shown in Table 2 using the core-sheath type composite fibers F and G. The two-layer fiber webs were each produced using a parallel card machine. The first layer fiber web (first non-woven fabric layer) and the second layer fiber web (second non-woven fabric layer) are laminated and heat-treated at 140 ° C. for 10 seconds using a hot air penetrating heat treatment machine to obtain a heat-bonded laminate. A non-woven fabric was obtained. In the heat treatment, the laminate of the first layer fiber web and the second layer fiber web was arranged on the metal net so that the surface of the first layer fiber web was in contact with the breathable metal net of the heat treatment machine.

(3) Evaluation and measurement method (3-1) Thickness The prepared non-woven fabric was measured at uniform intervals using a thickness measuring device, and the average value of n = 10 was taken as the thickness.

(3-2) Specific volume The specific volume was calculated by multiplying the area of the non-woven fabric for which the thickness was measured by the thickness and dividing this by the mass of the non-woven fabric, that is, dividing the thickness of the non-woven fabric by the scale. The reciprocal of the specific volume is the apparent density.

(3-3) Peel off the upper layer non-woven fabric of Lifree Urinary Pad (registered trademark) manufactured by Rewet Unicharm Co., Ltd., put a piece of tissue paper on the remaining absorber, and put the laminated non-woven fabric on it. The layered fiber web was placed so as to be on the upper side, 80 g of artificial urine was absorbed, and the mixture was left for 5 minutes. Next, a filter paper was placed on the portion where the artificial urine was absorbed, and a 3.5 kg weight was placed on the filter paper for 3 minutes. The load at this time was set to 3.5 kg / (15 cm × 15 cm). The weight was removed, the weight of the filter paper that absorbed artificial urine was measured, and the amount obtained by subtracting the weight of the filter paper was taken as the rewet amount. The same procedure was performed twice, and the first rewet amount and the second rewet amount were determined, respectively.

(3-4) Texture of non-woven fabric A sensory test was conducted with 10 people as monitors, and the texture of the non-woven fabric was scored according to the following evaluation criteria, and the average score was calculated. The items of the sensory test were softness and touch, and the texture of the non-woven fabric of Production Example 7 was used as a reference.
+5-Good +4-Slightly good +3-Neither (Manufacturing Example 7)
+ 2-Slightly bad + 1- Bad

(4) Results The non-woven fabrics obtained in Production Examples 1 to 6 had a short fiber non-woven fabric containing concentric core-sheath type composite fibers containing linear low-density polyethylene as a sheath component. Therefore, the non-woven fabric is excellent in softness and touch when touched by hand. Among the non-woven fabrics of Production Examples 1 to 6, the non-woven fabrics of Production Examples 1 to 5 in which the first layer has a smaller specific volume than the second layer, that is, the first layer has a higher apparent density than the second layer. , The amount of rewet is small. On the other hand, the non-woven fabrics obtained in Production Examples 7 and 8 did not have a short fiber non-woven fabric containing concentric core-sheath composite fibers containing linear low-density polyethylene as a sheath component (Production Example 7 is No. 7). One layer is a non-woven fabric containing an eccentric core-sheath type composite fiber, and Production Example 8 is a non-woven fabric containing a core-sheath type composite fiber in which the first layer contains high-density polyethylene as a sheath component), and the non-woven fabric is touched by hand. At that time, it became slightly inferior in softness or touch.

The non-woven fabric and laminated non-woven fabric of the present invention can be used for absorbent articles, medical non-woven fabric products, interpersonal wiping sheets, base cloths for patches, and the like.

Claims (5)

A laminated non-woven fabric having a first non-woven fabric layer and a second non-woven fabric layer.
The first non-woven fabric layer contains a thermoplastic resin whose sheath component contains linear low-density polyethylene and high-density polyethylene, and whose core component has a melting point higher than that of the linear low-density polyethylene by 20 ° C. or more. A short-fiber non-woven fabric containing a core-core sheath type composite fiber.
The second non-woven fabric layer is an eccentric core sheath type composite fiber or hollow core containing a high-density polyethylene as a sheath component and a thermoplastic resin having a core component having a melting point higher than that of the high-density polyethylene by 20 ° C. or more. A laminated non-woven fabric characterized by being a short-fiber non-woven fabric containing a sheath-type composite fiber. The laminated nonwoven fabric according to claim 1, wherein the concentric core-sheath type composite fiber has a crimp number of 10 to 30 fibers / 25 mm and a crimp rate of 10% to 30%. The laminated non-woven fabric according to claim 1 or 2 , wherein the apparent density of the first non-woven fabric layer is larger than the apparent density of the second non-woven fabric layer. The laminated nonwoven fabric according to any one of claims 1 to 3 , wherein the first nonwoven fabric layer and the second nonwoven fabric layer have a basis weight of 10 to 60 g / m ^{2, respectively.} Used for absorbent articles
The laminated non-woven fabric according to any one of claims 1 to 4 , wherein the first non-woven fabric layer is arranged on the contact surface side with the skin.