JP6523741B2 - Nonwoven fabric and method of manufacturing the same - Google Patents

Description

  The present invention relates to a non-woven fabric and a method of manufacturing the same.

  Various nonwoven fabrics using a latently crimpable conjugate fiber that develops a three-dimensional crimp when subjected to heat treatment have been proposed so far and put to practical use. For example, Patent Document 1 proposes using a non-woven fabric using a specific latently crimpable conjugate fiber as a bandage, a supporter, and a sanitary material such as a mask by utilizing its elasticity. Moreover, patent document 2 reports that the nonwoven fabric which shows the outstanding softness and touch is obtained by using latent crimpability conjugate fiber as a thermoadhesive fiber. Patent Document 3 has a latent crimpability which contains a specific linear low density polyethylene as a heat-shrinkable component, which is excellent in crimp development at low temperature and can also be used as a heat-adhesive fiber. We propose composite fiber.

JP 2012-12758 A Patent No. 3276578 Patent No. 3995 697

  The present invention was made for the purpose of providing a softer, better-feel nonwoven fabric using a latently crimpable conjugate fiber.

The present invention, in one aspect, is a crimped conjugate fiber having a three-dimensional crimp, comprising: a first component; and a second component having a melting point Tf ₂ higher than the melting point Tf ₁ of the first component. Crimped composite fiber,
A non-heat-shrinkable fiber having a dry heat shrinkage of 20% or less when measured at a temperature of 120 ° C. for 15 minutes and an initial load of 0.018 mN / dtex;
When the mass of the crimped conjugate fiber and the non-heat-shrinkable fiber is 100% by mass, the ratio of the crimpable conjugate fiber is 25% by mass to 85% by mass.
Constituent fibers are entangled,
Provided is a non-woven fabric in which the average value of the dimensional change rate in the longitudinal direction and the dimensional change rate in the lateral direction at (Tf ₁ -8) ° C. is 8% or more and 25% or less.

In another aspect of the present invention, a heat-shrinkable composite fiber comprising a first component and a second component having a melting point Tf ₂ higher than the melting point Tf ₁ of the first component, and a temperature of 120 ° C. for 15 minutes A non-heat-shrinkable fiber having a dry heat shrinkage ratio of 20% or less when measured under the condition of an initial load of 0.018 mN / dtex, the total weight of the heat-shrinkable composite fiber and the non-heat-shrinkable fiber Mixing to make the ratio of the heat-shrinkable composite fiber to 25% by mass or more and 85% by mass or less to form a fiber web;
Mechanical entanglement treatment is performed on the fiber web to entangle fibers constituting the fiber web,
Performing heat treatment after the confounding process;
Including
In the non-woven fabric obtained after the heat treatment, the heat treatment is performed such that the average value of the dimensional change in the longitudinal direction and the dimensional change in the lateral direction at (Tf ₁ -8) ° C. is 8% to 25%. Do,
Provided is a method for producing a non-woven fabric.

  The non-woven fabric of the present invention contains a crimped conjugate fiber which is not a fully developed three-dimensional crimp, and provides a soft, bulky and smooth touch because it is a configuration that can be further shrunk by heating.

FIGS. 1A to 1C are schematic views showing the form of three-dimensional crimp of a crimped conjugate fiber. FIG. 2 is a schematic view showing a form of three-dimensional crimp of the crimped conjugate fiber. FIG. 3 is a schematic view showing the form of mechanical crimp. FIG. 4 is a plan view schematically showing how to mark a length measurement section on a sample when obtaining an average value of dimensional change rates.

(Circumstances leading to the present invention)
The inventor of the present invention is a heat-shrinkable composite fiber (composed of a plurality of components (or phases), which develops a three-dimensional crimp by heating due to a difference in heat-shrinkability between the components Further, it was examined to improve the feel and the like of the non-woven fabric by using the crimped conjugate fiber. After making the fiber web, it is possible not only to provide stretchability to the non-woven fabric by making the heat-shrinkable composite fiber develop a three-dimensional crimp, but also a non-woven fabric different from that in the case of using normal fibers You can get The present inventor repeated studies considering that the expression of this three-dimensional crimp can be used to obtain a non-woven fabric more excellent in flexibility, bulkiness and touch.

  As a result, the degree of expression of steric crimp in the heat-shrinkable conjugate fiber affects the softness and feel of the non-woven fabric, and if it is incompletely expressed rather than fully expressed, the softness of the non-woven fabric And it turned out that the feeling improves. Furthermore, in order to make the non-woven fabric bulky, in addition to the heat-shrinkable composite fiber, it has been found that the use of a non-heat-shrinkable or low-heat-shrinkable fiber is effective. .

That is, the present inventors have set the heat treatment conditions so that the fiber web formed by mixing the heat shrinkable composite fiber and the non-heat shrinkable fiber at a predetermined ratio has a certain "heat shrink margin" even after heat treatment. It has been found that selective heat treatment can provide a nonwoven fabric excellent in touch feeling and the like. Specifically, heat treatment is carried out at a temperature significantly lower than the melting point of the heat shrinkable component constituting the heat shrinkable composite fiber, so that the heat shrinkable component is not completely thermally shrunk, and the temperature is higher than the temperature It was found that if the heat treatment conditions were selected so as to be further shrunk when heat treated, the softness, touch feeling and the like of the obtained nonwoven fabric were significantly improved.
Hereinafter, embodiments of the present invention will be described.

(Heat shrinkable composite fiber)
The nonwoven fabric of the present embodiment includes a crimped conjugate fiber having a three-dimensional crimp and a non-heat-shrinkable fiber at a predetermined ratio, and the dimensional change in the longitudinal direction and the dimensional change in the lateral direction at a predetermined temperature The nonwoven fabric having an average value of 8% or more and 25% or less. The crimped conjugate fiber having a three-dimensional crimp refers to a fiber in which the heat-shrinkable conjugate fiber is subjected to a heat treatment to develop a three-dimensional crimp. As described later, in the nonwoven fabric of the present embodiment, the crimped conjugate fiber exhibits shrinkage by being further subjected to a heat treatment, and in that sense, it can be called "heat-shrinkable conjugate fiber" . Here, a crimped conjugate fiber in a state where the three-dimensional crimp is not developed by heat treatment, that is, a heat-shrinkable conjugate fiber will be described.

The heat-shrinkable composite fiber includes a first component and a second component having a melting point Tf ₂ higher than the melting point Tf ₁ of the first component, and develops a three-dimensional crimp when subjected to a heat treatment . The first component exhibits higher heat shrinkability than the second component, and the contraction difference between the two components is used to express steric crimp. The heat-shrinkable conjugate fiber is present in the nonwoven fabric of the present embodiment in a state in which a three-dimensional crimp is developed by being subjected to a heat treatment, that is, as a crimpable conjugate fiber. Since this crimped conjugate fiber expresses a three-dimensional crimp such as a wave-shaped crimp or a helical crimp, which will be described later, the nonwoven fabric of the present invention including the crimped crimped crimped portion on the nonwoven fabric surface By being present, it not only exhibits a smooth and soft touch but also has appropriate stretchability by three-dimensional crimp.

The melting point Tf ₁ of the first component and the melting point Tf ₂ of the second component can be determined from the heat of fusion curve obtained by DSC. In the heat of fusion curve, two or more peaks may appear for one component. In that case, the temperature showing the largest peak is taken as the melting peak temperature, ie, the melting point.

  As the first component, for example, a propylene copolymer containing 50% by mass or more of propylene (hereinafter, simply referred to as "propylene copolymer"), an ethylene / α-olefin copolymer, a polyester-based copolymer, etc. It can be mentioned. Since these copolymers exhibit high heat shrinkability, the heat-shrinkable composite fiber containing this as the first component is likely to develop steric crimp.

Alternatively, as long as the first component has a difference in heat shrinkability and melting point from the second component, and can constitute a heat-shrinkable composite fiber exhibiting a three-dimensional crimp together with the second component, It may be a thermoplastic resin. Other thermoplastic resins are, for example, polyester resins such as polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polyethylene naphthalate, polylactic acid, polybutylene succinate and copolymers thereof, polypropylene, polyethylene (high density polyethylene (high density polyethylene (high density polyethylene)) Based resins such as low density polyethylene etc., polybutene-1, ethylene-vinyl alcohol copolymer, and ethylene-vinyl acetate copolymer, and polyamide resins such as nylon 6, nylon 12 and nylon 66 Etc.
The first component may comprise two or more thermoplastic resins.

  The first component may particularly contain 50% by mass or more, preferably 80% by mass or more of the propylene copolymer or the ethylene / α-olefin copolymer. Alternatively, the first component may be substantially only composed of a propylene copolymer or an ethylene / α-olefin copolymer without containing any other thermoplastic resin. Since these copolymers exhibit high heat shrinkability at relatively low temperatures, their use makes it possible to produce the nonwoven fabric of the present embodiment at relatively low temperatures. In addition, since these copolymers exhibit good heat adhesion, when the nonwoven fabric of the present embodiment is integrated with another member (for example, another nonwoven fabric or film) by thermal processing (for example, heat seal processing), The processability of the nonwoven fabric of this embodiment is made favorable. Hereinafter, these copolymers will be described.

  The propylene copolymer is a copolymer obtained by copolymerizing propylene and an α-olefin other than propylene, and contains propylene as a main monomer component. In the present embodiment, any propylene copolymer of random copolymer or block copolymer can be used. In consideration of heat shrinkability, random copolymers are preferred.

  In the propylene copolymer, monomers copolymerized with propylene include, for example, α-olefins having 2 to 20 carbon atoms such as ethylene, butene-1, hexene-1 and octene-1 (excluding propylene having 3 carbon atoms) And one or more monomers selected from The propylene copolymer is preferably at least one selected from an ethylene-propylene copolymer and an ethylene-butene-1-propylene terpolymer. In the case of an ethylene-propylene copolymer, the preferred copolymerization ratio is in the range of ethylene: propylene = 1: 99 to 20:80 by mass ratio. In the case of ethylene-butene-1-propylene terpolymer, the preferred copolymerization ratio is ethylene: butene-1: propylene = (0.5-15) :( 0.5-15) :( 70 in mass ratio ~ 99).

  The melt flow rate (MFR; measurement temperature 230 ° C., load 21.18 N (2.16 kgf)) of the propylene copolymer defined by JIS-K-7210 is preferably 50 g / 10 min or less, 15 g / 10 min. More preferably, it is in the range of from 30 minutes to 30 minutes. When the melt flow rate is in this range, the spinnability at the time of fiber production is good.

  The propylene copolymer preferably used can be specified as an ethylene-propylene random copolymer having a melting peak temperature of 145 ° C. or less, more specifically 130 ° C. or more and 145 ° C. or less. When the melting peak temperature is less than 130 ° C., the polymer exhibits rubbery elasticity and the cardability of the fiber is deteriorated. When the melting peak temperature exceeds 145 ° C., the heat shrinkability may be reduced, and the expression of steric crimp may be insufficient.

  An ethylene-alpha-olefin copolymer is a copolymer obtained by copolymerizing ethylene and an alpha-olefin, Comprising: Ethylene is used as a main monomer component. The ethylene / α-olefin copolymer is also referred to as linear low density polyethylene. The alpha-olefins generally have 3 to 12 carbons. Examples of α-olefins having 3 to 12 carbons are propylene, butene-1, pentene-1, 4-methylpentene-1, hexene-1, heptene-1, octene-1, nonene-1, decene- 1, dodecene-1 and mixtures thereof. Among these, propylene, butene-1, 4-methylpentene-1, hexene-1, 4-methylhexene-1 and octene-1 are particularly preferable, and butene-1 and hexene-1 are more preferable. The alpha-olefin content may be, for example, about 0.3 mol% to about 50 mol%, may be about 0.3 mol% to about 40 mol%, may be 0.4 mol% to about 10 mol%, or It may be out of these ranges.

Ethylene · alpha-olefin copolymer, for example, may have a density of about 0.900 g / cm ³ ~ about 0.940 g / cm ^3, preferably about 0.905 g / cm ³ ~ about 0.935 g / cm ^3, more preferably from about 0.910 g / cm ³ ~ about 0.935 g / cm ^3, even more preferably has a density of ^{0.913g / cm 3 ~0.933g / cm 3} . If the density is less than 0.900 g / cm ³ , the first component may be too soft and sufficient bulkiness and bulk recovery may not be obtained when it is made into a non-woven fabric. On the other hand, when the density of the ethylene / α-olefin copolymer is greater than 0.940 g / cm ³ , the surface texture and the flexibility in the thickness direction of the non-woven fabric may tend to be inferior when made into non-woven fabric.

  The melting point of the ethylene / α-olefin copolymer is preferably less than 130 ° C. When the melting point of the ethylene / α-olefin copolymer is 130 ° C. or higher, the temperature of the heat treatment needs to be increased to obtain the non-woven fabric in a state in which the predetermined heat shrinkage remains, and the non-woven fabric has a hard feel. Sometimes. The melting point of the ethylene / α-olefin copolymer may be, for example, 85 ° C. or more and 128 ° C. or less, 100 ° C. or more and 125 ° C. or less, or 105 ° C. or more and 125 ° C. or less Good.

  The ethylene / α-olefin copolymer may be polymerized using a metallocene catalyst. If a metallocene catalyst is used, an ethylene / α-olefin copolymer having the above-mentioned density, melting point and MI described later can be easily obtained. Alternatively, the ethylene / α-olefin copolymer is not limited to one polymerized using a metallocene catalyst, and may be one obtained by polymerization using a Ziegler-Natta catalyst, for example.

  The ethylene / α-olefin copolymer is preferably 1 g / 10 min to 60 g / 10 min, more preferably 2 g / 10 min to 40 g / 10 min, still more preferably 3 g / 10 min to 35 g / 10 min, in consideration of spinnability. Preferably, it has a melt index (MI) in the range of 5 g / 10 min to 30 g / 10 min. MI is measured according to JIS K 7210 (1999) (conditions: 190 ° C., load 21.18 N (2.16 kgf)). The larger the MI, the slower the solidification rate of the first component, and the fusion between the fibers. On the other hand, if the MI is too small, fiber production becomes difficult.

  The ratio (Q value: Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) in the ethylene / α-olefin copolymer is preferably 5 or less. The Q value is more preferably about 2 to about 4, and even more preferably about 2.5 to about 3.5. A Q value of 5 or less means that the width of the molecular weight distribution of the ethylene / α-olefin copolymer is narrow. By using an ethylene / α-olefin copolymer having a Q value in the above range as a sheath component, steric crimp develops better by heat treatment.

  When the first component contains an ethylene / α-olefin copolymer, the heat-shrinkable conjugate fiber itself becomes flexible and softens the feel of the non-woven fabric. In addition, since the ethylene / α-olefin copolymer can be thermally shrunk at a lower temperature as compared with the propylene copolymer, a heat-shrinkable composite containing the ethylene / α-olefin copolymer as the first component The fibers can develop steric crimp, for example, at less than 100 ° C., in particular at or below 90 ° C., making it possible to produce the nonwoven of this embodiment at relatively low heat treatment temperatures.

The second component has a higher melting point Tf ₂ than the melting point Tf ₁ of the first component. Tf ₂ may be 10 ° C. or more higher than Tf ₁ and in particular 15 ° C. or more. When the difference between Tf ₁ and Tf ₂ is small, good crimp expression may not be obtained.

  Examples of resins usable as the second component include polyester resins such as polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, and copolymers thereof, and polyamide resins such as nylon 6, nylon 66, and copolymers thereof, And polyolefin resins such as polypropylene and polymethylpentene. The second component may comprise two or more resins selected therefrom. The second component, although contracted, has a degree smaller than that of the first component, and serves to impart rigidity to the heat-shrinkable conjugate fiber and secure cardability of the fiber.

  The second component may contain 50% by mass or more, preferably 80% by mass or more of polypropylene having a melting point of 150 ° C. or more. Alternatively, the second component may be substantially free of polypropylene, without any other thermoplastic resin. Polypropylene is preferably used as the second component from the viewpoints of spinnability, crimpability of fibers, and shrinkability of the resin itself. In addition, polypropylene is a softer resin than polyester resin such as polyethylene terephthalate, so that it is more flexible than the heat-shrinkable conjugate fiber containing polyethylene terephthalate as the second component described later. It is considered to give a composite fiber.

  Alternatively, the second component may contain 50% by mass or more, preferably 80% by mass or more of polyethylene terephthalate. Also, the second component does not contain other thermoplastic resin, and may consist essentially of polyethylene terephthalate. Polyethylene terephthalate is excellent in spinnability, and a fiber containing this as the second component is excellent in crimp development. Furthermore, since polyethylene terephthalate is a resin having a high melting point and a large elasticity as compared with the above-described polypropylene resin, non-woven fabrics containing fibers contained in the second component are bulky even when heat-treated at a relatively high temperature. Is hard to reduce. Furthermore, since fibers composed of polyethylene terephthalate tend to increase the elasticity of the fibers themselves, heat-shrinkable composite fibers containing polyethylene terephthalate as the second component are suitable for applications where bulky nonwoven fabrics are required .

The heat-shrinkable conjugate fiber preferably has a cross-sectional structure in which the first component is exposed at a length of 20% or more with respect to the length of the circumferential surface of the fiber. As such a cross-sectional structure, an eccentric core-in-sheil cross-section in which the first component is a sheath component and the second component is a core component, and the center of gravity of the second component (core component) deviates from the center of gravity of the fiber; The parallel-type cross section in which the 1st ingredient and the 2nd ingredient were pasted together is mentioned. According to such a cross-sectional structure, it is possible to obtain a composite fiber which is excellent in shrinkability and excellent in crimp development.
When the heat-shrinkable composite fiber is an eccentric core-sheath composite fiber, the eccentricity of the second component is preferably in the range of 15 to 60%, and more preferably in the range of 20 to 50%. Preferably, it is particularly preferably in the range of 30 to 50%. The eccentricity here is defined by the following equation.

  The composite ratio of the first component and the second component may be in the range of 3: 7 to 7: 3 by volume ratio, preferably 4: 6 to 6: 4. If the ratio of the first component is too small, shrinkage may be insufficient, and if the ratio of the first component is too large, it may be difficult to pass the card at high speed when producing the non-woven fabric .

  The fineness of the heat-shrinkable conjugate fiber is not particularly limited. For example, the heat shrinkable conjugate fiber may have a denier of about 1.1 dtex to about 15 dtex, preferably has a denier of about 1.2 dtex to about 5 dtex, more preferably about 1.5 dtex to about 3.5 dtex. It may have a fineness of about 1.5 dtex to 2.5 dtex particularly preferably. The smaller the fineness, the smoother the feel of the nonwoven and the more flexible the nonwoven.

  The fiber length of the heat-shrinkable conjugate fiber is also not particularly limited. When producing a non-woven fabric, when making a fiber web using a carding machine, the fiber length may be in the range of about 1 mm to about 100 mm, preferably about 28 mm to about 72 mm, more preferably about 32 mm to about It is in the range of 64 mm. If an air laid machine is used, the fiber length may be in the range of about 3 mm to about 30 mm, preferably in the range of about 5 mm to about 25 mm.

  The heat-shrinkable conjugate fiber develops a three-dimensional crimp when subjected to a heat treatment. Here, the term "three-dimensional crimp" is used to distinguish it from a mechanical crimp in which the crest (or crest) of the crimp as shown in FIG. 3 has an acute angle. In addition, “a three-dimensional crimp is expressed” means, for example, a crimp in which a peak portion is curved as shown in FIG. 1A (wave-shaped crimp), and a peak portion as shown in FIG. Crush (helical crimp), a combination of wave-shaped crimp and spiral crimp as shown in FIG. 1C, and mechanical crimp and wave-shaped crimp as shown in FIG. It refers to the expression of a crimp in which at least one of the helical crimps is mixed.

As described above, in the nonwoven fabric of the present embodiment, a heat-shrinkable conjugate fiber after being subjected to a heat treatment, that is, a crimpable conjugate fiber having a three-dimensional crimp, is present, and this crimpable conjugate fiber is further heat-shrinkable It is possible. In the nonwoven fabric of the present embodiment, for example, the dry heat shrinkage ratio measured under the conditions of an initial load of 0.018 mN / dtex and a temperature Tf ₁ -3 ° C and a time of 15 minutes exceeds 20%. It may exist in the state which has heat shrinkability.

(Non-heat shrinkable fiber)
The non-heat-shrinkable fiber is a fiber having a dry heat shrinkage of 20% or less as measured at 120 ° C. for 15 minutes and an initial load of 0.018 mN / dtex, as long as the dry heat shrinkage is satisfied. Is not particularly limited. The non-heat-shrinkable fiber increases the bulk of the non-woven fabric of the present embodiment and plays a role of giving the non-woven fabric a proper stiffness to prevent the non-woven fabric from becoming thin and free from stiffness. If the non-woven fabric is thin and has no stiffness, not only wrinkles and breakages are likely to occur during winding on a roll during production, but also the non-woven fabric is easily deformed so that the non-woven fabric is punched into a specific shape. Sometimes it can not be carried out, or the shape to be punched out tends to break down.

  For example, non-heat-shrinkable fibers include natural fibers such as cotton, silk, wool, hemp, and pulp, regenerated fibers such as rayon, cupra, and solvent-spun cellulose fibers, and acrylics, polyethylene terephthalate, polybutylene terephthalate, poly Polyesters such as trimethylene terephthalate, polyethylene naphthalate, polylactic acid, and polybutylene succinate and copolymers thereof, amides such as nylon 6, nylon 12 and nylon 66, polypropylene, polyethylene (high density polyethylene, low density polyethylene And polyolefins such as polybutene-1, ethylene-vinyl alcohol copolymer, and ethylene-vinyl acetate copolymer, and synthetic fibers such as polyurethane. Synthetic fibers as non-heat-shrinkable fibers may be single fibers or composite fibers. For example, the bicomponent fibers may be core-sheath bicomponent fibers or split bicomponent fibers. Moreover, you may use combining a 2 or more fiber as a non-heat-shrinkable fiber.

  The non-heat-shrinkable fiber may be, for example, a single fiber made of polypropylene or polyethylene terephthalate (hereinafter, "polypropylene fiber"). These single fibers are preferably used because they are easily available and relatively small in size. In particular, when the heat-shrinkable composite fiber contains ethylene / α-olefin copolymer or propylene copolymer as the first component, the polypropylene resin itself is a polyester resin and the non-heat-shrinkable fiber is a polypropylene fiber. Because it is softer than other thermoplastic resins such as polyamide resin, it is easy to obtain a soft, smooth nonwoven fabric. In addition, since polypropylene resin has a low melting point as compared with polyester resin and polyamide resin, using polypropylene fiber can not only heat bond at lower temperature, but also heat when partially bonding the obtained nonwoven fabric. Adhesion is also good.

  The fineness of the non-heat-shrinkable fiber is not particularly limited. For example, when the non-heat-shrinkable fiber is a regenerated fiber or a synthetic fiber, its fineness may be about 0.3 dtex to about 15 dtex, preferably about 0.5 dtex to about 5 dtex, more preferably about 0 8 dtex to about 3.5 dtex, particularly preferably about 0.8 dtex to about 2.0 dtex. The smaller the fineness, the smoother the feel of the nonwoven and the more flexible the nonwoven. The fineness of the non-heat-shrinkable fiber may be the same as or different from that of the heat-shrinkable conjugate fiber, and is preferably smaller than the fineness of the heat-shrinkable conjugate fiber. If the fineness of the non-heat-shrinkable fiber is smaller than the fineness of the heat-shrinkable composite fiber, it is easy to obtain a non-woven fabric having a smooth and soft touch.

  The fiber length of the non-heat shrinkable conjugate fiber is also not particularly limited. When producing a non-woven fabric, when making a fiber web using a carding machine, the fiber length may be in the range of about 1 mm to about 100 mm, preferably about 28 mm to about 72 mm, more preferably about 32 mm to about It is in the range of 64 mm. If an air laid machine is used, the fiber length may be in the range of about 3 mm to about 30 mm, preferably in the range of about 5 mm to about 25 mm.

(Non-woven fabric composition)
Then, the composition of the nonwoven fabric of this embodiment is explained. The nonwoven fabric of the present embodiment includes a crimped conjugate fiber having a three-dimensional crimp and a non-heat-shrinkable conjugate fiber, and the mass of the crimped conjugate fiber and the non-heat-shrinkable fiber is 100% by mass. It is a non-woven fabric in which the proportion of crimped conjugate fibers is 25% by mass to 85% by mass, and the constituent fibers are entangled. Furthermore, the nonwoven fabric of this embodiment is an average value of the dimensional change in the longitudinal direction and the dimensional change in the lateral direction at (Tf ₁ -8) ° C. (Tf ₁ is the melting point of the first component of the crimped conjugate fiber). Has a heat shrinkability of 8% or more and 25% or less.

  The crimped conjugate fiber having a three-dimensional crimp is a fiber in which the heat-shrinkable conjugate fiber is subjected to a heat treatment to develop a three-dimensional crimp. In the crimped conjugate fiber, the three-dimensional crimp may be expressed in a number of 40/25 mm or more and 700/25 mm or less, particularly 50/25 mm or more and 600/25 mm or less. In the crimped conjugate fiber, when mechanical crimp and wave-shaped crimp and / or helical crimp are mixed and expressed, mechanical crimp is also included in the number of the above-mentioned three-dimensional crimps. The number of crimps in the crimped conjugate fiber contained in the non-woven fabric can be measured according to JIS L 1015 by removing the fiber from the non-woven fabric so that the three-dimensional crimp does not extend completely. Alternatively, when the crimped conjugate fiber having a three-dimensional crimp is strongly entangled with other fibers and it is difficult to take it out of the non-woven fabric, the enlarged surface or cross section of the non-woven fabric is photographed with a scanning electron microscope or the like. The number of crimps and the length of the crimped conjugate fiber may be measured in the range observed in the photographed photograph, and the number of crimps may be determined by a method of converting it into the number of crimps per 25 mm. In the crimped conjugate fiber in the present embodiment, the first component is not completely thermally shrunk, whereby the above-described thermal shrinkage is left in the nonwoven fabric.

  The crimped conjugate fiber is contained in a proportion of 25% by mass to 85% by mass, preferably 35% by mass, when the mass of the crimped conjugate fiber and the non-heat-shrinkable fiber is 100% by mass. It is contained at a ratio of at least 80 mass%, more preferably at least 40 mass% and at most 80 mass%, particularly preferably at least 45% and at most 75%. When the proportion of the crimped conjugate fiber is too small, the total number of three-dimensional crimps decreases, and an effect such as smooth touch may not be obtained. If the proportion of the crimped conjugate fiber is too large, the proportion of the non-heat-shrinkable fiber tends to be small, and the bulk of the non-woven fabric tends to be small, and a pill is formed on the non-woven surface to reduce the feel. Sometimes.

  In the nonwoven fabric of the present embodiment, when the mass of the crimpable conjugate fiber and the non-heat-shrinkable fiber is 100% by mass, the crimpable conjugate fiber is contained in the above ratio, as long as it is 100% by mass. It may contain fibers. Other fibers do not have, for example, a three-dimensional crimp, and a fiber whose dry heat shrinkage percentage measured under conditions of an initial load of 0.018 mN / dtex and a temperature of 120 ° C. and a time of 15 minutes exceeds 20% It is. When other fibers are included, the proportion is preferably 25% by mass or less of all the fibers constituting the non-woven fabric. When the proportion of the other fibers is increased, the effect (for example, smooth touch) exerted by the crimped conjugate fiber and the non-heat-shrinkable fiber may not be sufficiently obtained.

  The nonwoven fabric of the present embodiment is integrated by interlacing constituent fibers. As described below, the fibers may be entangled by needle punching or fluid flow (especially water flow) entanglement. A nonwoven fabric integrated by interlacing fibers is more flexible. In the non-woven fabric of the present embodiment, it is preferable that the fibers are not thermally bonded from the viewpoint of the softness of the non-woven fabric. This is because the non-woven fabric tends to become hard by heat bonding.

As described above, the non-woven fabric of the present embodiment is heat-shrinkable. The heat shrinkability of the non-woven fabric is evaluated by the dimensional change rate at (Tf1-8) ° C., which is measured according to the following method.
(1) Three pieces of test specimens of about 100 mm × about 100 mm are collected from the non-woven fabric.
(2) As shown in FIG. 4, in this test piece, a mark representing a length of about 83 mm is provided at three locations in each of the longitudinal direction and the lateral direction (hereinafter referred to as a length measurement section). In FIG. 4, the length measurement section in the vertical direction is indicated by a thick solid line.
(3) For each test piece, measure the length of each of the three length measurement sections in the longitudinal direction and the lateral direction to 0.1 mm, and determine the average value of the lengths of the length measurement sections in each direction. The “pre-processing length” (ΔL _MD1 : pre-processing length in the vertical direction, ΔL _CD1 : pre-processing length in the vertical direction) of the measurement section.
(4) Prepare a thermostatic dryer set to (Tf1-8) ° C., and hold the corner of the test piece vertically suspended in the thermostatic dryer and suspend it. After reaching the set temperature again, leave the sample in the dryer for 3 minutes. After 3 minutes, remove the test piece and cool to room temperature.

（７）同様に、（２）で求めた、各試料片における横方向の３つの測長区間の処理前長さの平均値（ΔL_CD1）、（５）で求めた、横方向の３つの測長区間の処理後長さの平均値（ΔL_CD2）から、下記の式に従って各試験片の横方向の寸法変化率（ΔL_CD）を算出する。

（８）（６）および（７）で求めた縦方向の寸法変化率ΔL_MDと横方向の寸法変化率ΔL_CDの平均値から縦方向の寸法変化率および横方向の寸法変化率の平均値（ΔL_ave）を下記の式に従って算出する。

（９）３点の試験片についてΔL_aveを算出し、これらの値の平均値をその不織布における縦方向の寸法変化率および横方向の寸法変化率の平均値とする。 (5) For the cooled test piece, measure the length of each of the three length measurement sections in the longitudinal direction and the lateral direction to 0.1 mm, determine the average value of the length measurement sections in each direction, and measure each length The “post-processing length” of the section (ΔL _MD2 : post-processing length in the vertical direction, ΔL _CD2 : post-processing length in the vertical direction).
(6) Average value (ΔL _MD1 ) of the pre-treatment length of the three length measurement sections in the vertical direction obtained in (2), 3 in the vertical direction in each sample obtained in (5) From the average value (ΔL _MD2 ) of the post-processing length of one of the length measurement sections, the dimensional change rate (ΔL _MD ) in the longitudinal direction of each test piece is calculated according to the following equation.

(7) Similarly, the average value (ΔL _CD1 ) of the pre-treatment lengths of three measurement segments in the lateral direction in each sample piece determined in (2), three in the lateral direction determined in (5) from length measuring process after the length of the average value of the interval ([Delta] L _CD2), calculated lateral dimensional change of each specimen ([Delta] L _CD) according to the following equation.

(8) From the average value of the dimensional change rate ΔL _{MD in} the longitudinal direction and the dimensional change rate ΔL _{CD in} the lateral direction determined by (6) and (7), the average value of the dimensional change rate in the longitudinal direction and the dimensional change rate in the lateral direction Calculate (ΔL _ave ) according to the following equation.

(9) _ΔLave is calculated for three test pieces, and the average value of these values is taken as the average value of the dimensional change rate in the longitudinal direction and the dimensional change rate in the lateral direction in the nonwoven fabric.

The average value of the dimensional change rate in the longitudinal direction and the dimensional change rate in the lateral direction at (Tf ₁ -8) ° C. (hereinafter referred to simply as “average value of dimensional change rate”) is 8% or more and 25% or less The crimped conjugate fiber has an adequate three-dimensional crimp, so that the feel of the non-woven fabric becomes good and a smooth touch can be obtained, and the non-woven fabric has an appropriate stretch and contraction due to an appropriate three-dimensional crimp. Become sexual. When the average value of the dimensional change rate is small, the degree of occurrence of steric crimp in the crimped conjugate fiber is larger, and a large number of helical fine crimps are expressed. Such a three-dimensional crimp causes unevenness on the surface of the non-woven fabric and not only reduces the feel of the non-woven fabric, but also causes the nonwoven fabric to have a high-density structure overall, so that the drapability of the non-woven fabric is lost. . Alternatively, a non-woven fabric having a small average value of dimensional change may have a low content of crimped conjugate fibers and may not have a sufficient number of three-dimensional crimps to smooth the surface of the non-woven fabric. In addition, when the content of the crimped conjugate fiber is small, the entanglement between the fibers becomes weak, and when the non-woven fabric is manufactured without heat-adhering the fibers, bonding between the fibers by the entanglement becomes insufficient. The fuzz may be increased, and when the fibers are thermally bonded to produce a non-woven fabric, the surface may be rough.

  On the other hand, when the average value of the dimensional change rate is large, the degree of expression of steric crimp in the crimped conjugate fiber may be small, and a smooth touch due to steric crimp may not be obtained. In addition, in the process in which the steric crimp develops, intermingling of the fibers and bonding between the fibers by the entanglement progresses, so that when the degree of steric crimp is small, the inter-fiber bonding is obtained in the obtained non-woven fabric It may be inadequate and prone to fiber loss and fuzzing.

  In order to bring the average value of dimensional change into the above range, the proportion of crimped conjugate fibers, the degree of interlacing between fibers, and the degree of three-dimensional crimp in crimped conjugate fibers (that is, a heat-shrinkable composite One or more parameters selected from the heat treatment conditions of the fiber etc. are adjusted. For example, when the degree of interlacing between fibers is too high, the average value of the dimensional change tends to be small. In addition, when the degree of three-dimensional crimp in the crimped conjugate fiber is high (that is, the heat treatment temperature is high or the heat treatment time is long), the average value of the dimensional change tends to be small. By appropriately adjusting and combining these parameters, an average value of predetermined dimensional change rates can be obtained.

  The nonwoven fabric of the present embodiment in which the average value of the dimensional change rate is within the above range has a smooth feel. Specifically, the nonwoven fabric of the present embodiment has an average deviation (SMD) of surface roughness measured on the surface of the nonwoven fabric of 3.6 μm or less. SMD is measured and evaluated based on KES (Kawabata Evaluation System). KES is one of the methods for measuring and objectively evaluating the texture of a fabric, and SMD is one of the characteristic values of surface friction defined by KES.

  Larger SMDs indicate that the surface is less flat. The device used to measure the SMD is not particularly limited as long as it can measure surface friction based on KES. The characteristic value of the surface friction can be measured, for example, using a KES-SE friction tester, a KES-FB4-AUTO-A automated surface tester (both manufactured by Kato Tech Co., Ltd.), and the like. The surface friction can be measured with the static load as 25 gf and the moving speed of the friction element as 1 mm / sec, with the longitudinal direction of the nonwoven fabric as the measuring direction. At least one surface of the non-woven fabric preferably has an SMD of 3.6 or less, more preferably 3.0 or less, even more preferably 2.5 or less, and most preferably 1.9 or less. Nonwoven surfaces having an SMD of 3.6 or less have less asperities and provide a smoother surface feel to the product. The lower limit of SMD is not particularly limited, and is preferably close to 0, but may be 0.3 or 0.5.

The basis weight of the non-woven fabric is not particularly limited, and may be appropriately selected depending on the application and the like. Basis weight of the nonwoven fabric may be, for example, ^{30g / m 2 ~150g / m 2} . More specifically, a non-woven fabric, a skin (including cosmetics) impregnated skin covering sheet including a face mask, a packaging material of a heating element in a heating implement including a disposable thermal insulation, a base cloth of a skin contact surface, and a product surface material, when used as hot compresses and backing various poultice materials, including cold compress, and various dressings of the medical, the basis weight may as ^{50g / m 2 ~120g / m 2} , 55g / m 2 may be a to 100 g / ^{m 2,} may be ^{60g / m 2 ~90g / m 2} .
The thickness of the nonwoven fabric is not particularly limited, for example, in the case of non-woven fabric having a basis weight of ^{30g / m 2 ~150g / m 2} , the thickness can be 0.5 mm to 5 mm, 0.6Mm～3.5Mm It may be 0.6 mm to 3.0 mm or 0.7 to 2.5 mm.

The non-woven fabric of the present embodiment can be provided as bulky because it includes the specific fibers and has a “heat-shrinkable margin”. The bulkiness of the non-woven fabric can be expressed by a specific volume, and the specific volume is calculated by dividing the thickness by the basis weight. However, it should be noted that the specific volume also varies depending on the non-woven fabric storage state and / or the non-woven fabric production process. For example, when the non-woven fabric is wound around the core and stored in a roll form, the specific volume of the non-woven fabric closer to the core tends to be smaller. For example, the nonwoven fabric of the present invention, immediately after production, preferably 10cm ³ / g~40cm ³ / g, more preferably has a specific volume of 15cm ³ / g~30cm ³ / g. The specific volume is a thickness measured while applying a load of 2.94cN per nonwoven 1 cm ^2, is calculated from the basis weight of the nonwoven fabric.

(Method of manufacturing non-woven fabric)
In the nonwoven fabric of the present embodiment, the heat-shrinkable composite fiber described above and the non-heat-shrinkable fiber described above are 100% by mass of the heat-shrinkable composite fiber and the non-heat-shrinkable fiber. Sometimes, the ratio of the heat-shrinkable composite fiber is mixed so as to be 25% by mass or more and 85% by mass or less to prepare a fiber web, and the fiber web is subjected to mechanical entanglement treatment to form a fiber web These fibers are entangled and then heat-treated.

The fibrous web may comprise other fibers besides heat shrinkable composite fibers and non-heat shrinkable fibers. Examples of the other fibers and their proportions are as described above in connection with the non-woven fabric, and thus the description thereof is omitted here.
The form of the fibrous web may be any selected from parallel webs, cross webs, carded webs such as semi-random webs and random webs, air-laid webs, spunbond webs and the like. In the present embodiment, a card web is preferably used in terms of the interlacing property of the fibers.

Mechanical entanglement of the fibers may be performed, for example, by needle punching or fluid flow (especially water flow) entanglement. In the present embodiment, in particular, needle punching is preferably used. According to the needle punching process, since the fibers are not excessively entangled, it is easy to obtain a bulkier and softer non-woven fabric. In addition, according to the needle punching process, adjustment of the degree of interlacing of fibers is easy, and it becomes easy to obtain an average value of the desired dimensional change (heat shrinkage margin). Needle punch processing can be carried out using a conventional needle punch machine. In the needle punching process, for example, the number of barbs is 3 to 12 and the needle depth is 36 mm to 42 mm, the needle depth is 3 mm to 20 mm, and 30 needles / cm ^{2 to} 500 needles / cm ² It is good to carry out by driving at a density (the number of needle strikes per unit area, also referred to as the number of penes).

Next, the fiber web after the entanglement treatment is heat-treated to develop a three-dimensional crimp in the heat-shrinkable composite fiber. The heat treatment is carried out such that the average value of the dimensional change rate in the longitudinal direction and the dimensional change rate in the transverse direction at (Tf ₁ -8) ° C. is 8% or more and 25% or less in the nonwoven fabric obtained after the heat treatment. That is, the heat treatment is carried out so that the non-shrinkage of the heat-shrinkable composite fiber does not occur excessively so that the non-woven fabric obtained after the heat treatment has a "heat-shrinkable margin".

The heat treatment temperature and the heat treatment time are selected according to the resin constituting the heat-shrinkable composite fiber so that the degree of three-dimensional crimp does not become too strong, and in particular, the melting point Tf ₁ of the first component is It is selected in consideration. When the heat treatment is performed at a temperature close to Tf ₁ , thermal contraction of the first component (that is, expression of steric crimp) proceeds too much, making it difficult to leave a thermal contraction margin in the non-woven fabric. For example, the heat treatment temperature may be 10 ° C. to 30 ° C. lower than Tf ₁ , and the heat treatment time may be 0.2 seconds to 30 seconds.

  More specifically, the first component of the heat-shrinkable conjugate fiber contains ethylene / α-olefin copolymer, and the first component is exposed at a length of 20% or more with respect to the length of the circumferential surface of the fiber In the case of composite fibers, the heat treatment temperature is preferably 78.degree. C. or more and less than 98.degree. C., more preferably 80.degree. C. or more and less than 95.degree. When heat treatment is carried out in this temperature range, the heat treatment time is preferably 0.5 seconds or more and 15 seconds or less. On the other hand, when the first component of the heat-shrinkable composite fiber contains a propylene copolymer, and the first component is a composite fiber exposed at a length of 20% or more with respect to the length of the circumferential surface of the fiber The heat treatment temperature is preferably 100 ° C. or more and less than 125 ° C., more preferably 110 ° C. or more and less than 120 ° C. When heat treatment is carried out in this temperature range, the heat treatment time is preferably 0.5 seconds or more and 15 seconds or less.

  The heat treatment is preferably a hot air processing process where hot air is applied to the fibrous web. According to the hot-air processing, the pressure applied in the thickness direction of the fiber web can be reduced, and a three-dimensional crimp is unlikely to be crushed, and a bulky nonwoven fabric can be obtained. The hot air processing may be performed using, for example, a hot air penetration heat treatment machine and a hot air blowing heat treatment machine. Alternatively, heat treatment using infrared light may be performed instead of hot air processing. Thermal treatment by infrared radiation is also preferably used because pressure is less likely to be applied to the fiber web. Alternatively, the heat treatment may be performed by a method using a heat roll.

  In addition to the above conditions, the heat treatment may be carried out by selecting conditions such that the fibers constituting the fiber web do not thermally bond. When thermal adhesion occurs between the constituent fibers, as described above, the resulting non-woven fabric may become hard and lose its feel and flexibility.

(Use)
The nonwoven fabric of the present embodiment can be used for various applications and is preferably used for applications requiring softness and good touch, for example, a product for skin contact to be used by directly applying to the skin, in which case the nonwoven fabric of the present embodiment is , Occupy at least a part of the surface that contacts the skin. Liquid for skin contact products include, for example, sanitary products such as masks, supporters and bandages, absorbent articles such as disposable diapers, sanitary napkins, and sheet for cages, liquid-impregnated skin covering sheets impregnated with liquids such as cosmetics For example, it is a face mask, a keratin care sheet, a decollete sheet, etc.), a packaging material of a heating element in a heating implement including a disposable body warmer, and a base cloth of various pap materials including a heat compress and a cold compress.

  For example, in the mask, the nonwoven fabric of the present embodiment may constitute the mask body by itself, or as a two-layer structure with another nonwoven fabric, the nonwoven fabric of the present embodiment is disposed on the side in contact with the face Good. In the case of an absorbent article, the nonwoven fabric of the present embodiment may be used as the top sheet. In the case of a supporter, a bandage, a liquid-impregnated skin covering sheet, etc., the nonwoven fabric of the present embodiment may constitute the product body by itself, or the nonwoven fabric of the present embodiment has skin as a two-layer structure with other nonwoven fabrics. It may be arranged on the contact side.

The following fibers were prepared.
(1) Heat shrinkable composite fiber 1
As the heat-shrinkable composite fiber 1, the first component is composed of an ethylene / α-olefin copolymer polymerized using a metallocene catalyst, the second component is composed of polypropylene, and the first component is the length of the circumferential surface of the fiber In contrast, it is a composite fiber having a parallel-type cross section in which the first component and the second component are bonded and is exposed by 20% or more, and the fineness is 4.4 dtex, 3.3 dtex, 2.2 dtex, 1.7 dtex Prepared ones. The composite ratio of the first component and the second component was 50/50 (volume ratio) for all finenesses.
The ethylene / α-olefin copolymer as the first component had a melting point of 108 ° C., a density of 0.918 g / cm ³ , an MI of 7 g / 10 min, and a Q value of 3.0 (trade name: 420 SD, Ube Maruzen made of polyethylene).
The polypropylene as the second component had a melting point of 160 ° C. (trade name: SA03, manufactured by Nippon Polypropylene Corporation).

(2) Heat shrinkable composite fiber 2
As the heat-shrinkable conjugate fiber 2, the first component is made of a propylene copolymer in which ethylene and propylene are copolymerized, the second component is made of polypropylene, and the first component is based on the length of the circumferential surface of the fiber A composite fiber having a side-by-side cross section in which the first component and the second component were bonded together and having a denier of 2.2 dtex or 1.7 dtex was prepared. The composite ratio of the first component and the second component was 50/50 (volume ratio) for all finenesses.
The propylene copolymer as the first component had a melting point of 140 ° C., an MFR of 30 g / 10 minutes, and a ratio of ethylene of 4.78% by mass (trade name: Y2045 GP, manufactured by Prime Polymer Co., Ltd.).
The polypropylene as the second component had a melting point of 160 ° C. (trade name: SA03, manufactured by Nippon Polypropylene Corporation).

(3) Non-heat shrinkable fiber 1
As the non-heat-shrinkable fiber 1, a single fiber having a fineness of 1.0 dtex and made of polypropylene having a melting point of 160 ° C. was prepared. The dry heat shrinkage (120 ° C. dry heat shrinkage) measured under the conditions of a temperature of 120 ° C., a time of 15 minutes and an initial load of 0.018 mN / dtex was 0.5% or less. The method of determining the 120 ° C. dry heat shrinkage rate is as follows.
[120 ° C dry heat shrinkage rate]
In accordance with JIS L 1015, the dry heat shrinkage was measured at an initial load of 0.018 mN / dtex with a gripping interval of 100 mm, a treatment temperature of 120 ° C., a treatment time of 15 minutes, and an initial load of 0.018 mN / dtex. The 120 ° C. dry heat shrinkage was calculated according to the following equation.
120 ° C. dry heat shrinkage (%) = [(length of sample before dry heat treatment−length of sample after dry heat treatment) / (length of sample before dry heat treatment)] × 100

(Examples 1 to 5, Comparative Examples 1 to 7)
The heat-shrinkable composite fibers and the non-heat-shrinkable composite fibers shown in Tables 1 and 2 were mixed in the proportions shown in Tables 1 and 2 to make a fiber web using a parallel card machine. The obtained fiber web was subjected to a needle punching process to entangle the fibers. Needle punch processing was performed using a 40 th needle (the number of barbs: 9) at a needle depth of 5 mm and under conditions of a pene number of 100 / cm ² . Subsequently, heat treatment was performed for 20 seconds with a hot-air-through type heat treatment machine set to the temperature shown in Table 1, and a three-dimensional crimp was developed in the heat-shrinkable conjugate fiber to obtain a non-woven fabric.

(Examples 6 to 7)
The heat-shrinkable composite fibers and the non-heat-shrinkable composite fibers shown in Table 1 were mixed in the proportions shown in Table 1 to prepare a fiber web using a parallel card machine. The obtained fiber web was subjected to a needle punching process to entangle the fibers. Needle punch processing was performed using a 40 th needle (the number of barbs: 9) at a needle depth of 8 mm and under conditions of a pene number of 120 / cm ² . Then, it heat-treated for 10 seconds with the hot-air penetration type heat processing machine set to the temperature shown in Table 1, three-dimensional crimp was expressed in the heat-shrinkable composite fiber, and the nonwoven fabric was obtained.

  The evaluation results of the non-woven fabrics obtained in Examples 1 to 7 and Comparative Examples 1 to 7 are shown in Tables 1 and 2. In addition, each evaluation was implemented according to the following method.

[Thickness of non-woven fabric]
Using a thickness measuring instrument (trade name THICKNESS GAUGE Model CR-60A (Ltd.) Daiei Kagaku Seiki Seisakusho) was measured while applying a load of 2.94cN per sample 1 cm ^2.

[Dimensional change of nonwoven fabric]
First, in accordance with the method described in the section “(non-woven fabric configuration)”, the longitudinal and transverse dimensional change rates, and the average of the longitudinal dimensional change rates and the transverse dimensional change rates were determined. The measurement temperature of the dimensional change was set to 100 ° C. for the non-woven fabric containing the heat-shrinkable composite fiber 1 and to 132 ° C. for the non-woven fabric containing the heat-shrinkable composite fiber 2.

[Feeling evaluation of nonwoven fabric]
The surface of the non-woven fabric was hand-touched by five monitors, and the softness, smoothness and fluff of the non-woven surface were evaluated according to the following criteria, and the evaluation obtained by the most monitors was regarded as the evaluation of the non-woven fabric.
[Flexibility]
++: The feeling of touch when touched is particularly soft, and the familiarity to the skin (followability to the unevenness of the skin) is particularly good.
+: Soft touch when touching and good familiarity with skin.
-: The touch is hard when touched, does not follow the unevenness of the skin, and is not familiar.
[Smoothness]
++: I do not feel the irritating sensation when I brow the surface.
+: Less irritating feeling when rubbing the surface.
-: There is a rough feeling when rubbing the surface.
[Fuzzing on the surface]
+: The fluff on the surface is inconspicuous, and it is slight if it can be confirmed with the naked eye.
-: Fluffs are noticeable on the surface and can be easily confirmed with the naked eye.

[SMD]
The surface friction is measured using a KES-SE friction tester (Kato Tech Co., Ltd.), with the static load 25 gf and the moving speed of the friction element 1 mm / sec, with the vertical direction of the nonwoven fabric as the measurement direction. The mean deviation of the roughness was determined.

  In each of the nonwoven fabrics of Examples 1 to 7, the average value of the dimensional change rate in the longitudinal direction and the dimensional change rate in the lateral direction is in the range of 8% to 25%, and both the softness and the smoothness are “+”. It is the above and fluff did not generate | occur | produce on the nonwoven fabric surface. Moreover, SMD which measured the roughness of the nonwoven fabric surface mechanically was 3.6 or less. These results indicate that the temperature at which a composite fiber expressing a three-dimensional crimp by heat treatment and a non-heat-shrinkable fiber are mixed and a moderate three-dimensional crimp is expressed, in other words, a temperature at which a three-dimensional crimp is not maximally expressed. By heat treatment to produce a non-woven fabric, the fibers become hard under the influence of heat, and in some cases the thermoplastic resin does not melt or thermally bond, so that it becomes a soft and smooth non-woven fabric, as well as appropriate It is considered that this is because the entanglement between the fibers can be fixed to some extent and fluff on the surface of the fibers is suppressed because the three-dimensional crimp is expressed.

  In the nonwoven fabrics of Comparative Examples 1, 2 and 7, the heat treatment temperature was high, and the average value of the dimensional change rate in the longitudinal direction and the dimensional change rate in the lateral direction was both less than 8%. Therefore, many fine three-dimensional crimps are formed in the crimped conjugate fiber, and there is a feeling of irritation that is presumed to be caused by the crimped shape, and the SMD is also large. The non-woven fabric of Comparative Example 3 was produced using only the heat-shrinkable conjugate fiber, and not only because its specific volume is small, but also because it is composed of only fibers that exhibit three-dimensional crimp, The sensation of irritation that was presumed to be due to the crimped shape was confirmed. In the nonwoven fabric of Comparative Example 4, as in the nonwoven fabric of Comparative Example 3, most of the fibers constituting the nonwoven fabric are crimped composite fibers, so that not only the specific volume of the nonwoven fabric is small, but also the fibers expressing a three-dimensional crimp. Since the ratio was high, a feeling of stimulation presumed to be caused by the crimped shape was confirmed.

  The nonwoven fabric of Comparative Example 5 is excellent in terms of softness and smoothness because it is composed of only non-heat-shrinkable fibers of fineness, but it does not contain a crimpable conjugate fiber, so The entanglement and the bonding between fibers due to the entanglement were insufficient, and the surface was clearly fuzzed. The nonwoven fabric of Comparative Example 6 contains crimped conjugate fibers and non-heat-shrinkable fibers in the same proportions as in Examples 1 to 3 and 5 to 7, but the crimped composite is because the heat treatment temperature is too low. The expression of fiber steric crimp was insufficient. Therefore, as in the case of the nonwoven fabric of Comparative Example 5, entanglement of fibers and bonding between the fibers due to entanglement were insufficient, and fuzz was clearly generated on the surface. In the nonwoven fabric of Comparative Example 6, it can be confirmed from the fact that the average value of the dimensional change rate in the longitudinal direction and the dimensional change rate in the lateral direction exceeds 25% that the expression of the three-dimensional crimp is insufficient.

The present invention includes the following aspects.
(Aspect 1)
A crimped conjugate fiber having a three-dimensional crimp, comprising: a first component; and a second component having a melting point Tf ₂ higher than the melting point Tf ₁ of the first component;
A non-heat-shrinkable fiber having a dry heat shrinkage of 20% or less when measured at a temperature of 120 ° C. for 15 minutes and an initial load of 0.018 mN / dtex;
When the mass of the crimped conjugate fiber and the non-heat-shrinkable fiber is 100% by mass, the ratio of the crimpable conjugate fiber is 25% by mass to 85% by mass.
Constituent fibers are entangled,
(Tf 1 _-8) average of longitudinal dimensional change and transverse dimensional change of at ℃ is 25% or less than 8%, the nonwoven fabric.
(Aspect 2)
The nonwoven fabric of embodiment 1, wherein the constituent fibers are not thermally bonded.
(Aspect 3)
In the crimped conjugate fiber, the first component contains 50% by mass or more of a propylene copolymer or an ethylene / α-olefin copolymer having a melting point of 145 ° C. or less, and the first component has a circumference of the fiber The nonwoven fabric according to aspect 1 or 2, which is a composite fiber exposed at a length of 20% or more with respect to the length of the surface.
(Aspect 4)
In the crimped conjugate fiber, the first component contains 50% by mass or more of an ethylene / α-olefin copolymer having a melting point of less than 130 ° C.,
The nonwoven fabric of embodiment 3, wherein the ethylene / α-olefin copolymer is a linear low density polyethylene polymerized using a metallocene catalyst.
(Aspect 5)
The nonwoven fabric according to any one of aspects 3 or 4, wherein the second component of the crimped conjugate fiber contains 50% by mass or more of polypropylene having a melting point of 150 ° C. or more.
(Aspect 6)
The fiber cross section of the crimped conjugate fiber is an eccentric core-in-sheath cross section in which the first component is a sheath component, the second component is a core component, and the center of gravity of the second component is offset from the center of gravity of the fiber. The nonwoven fabric according to any one of aspects 1 to 5, which is a side-by-side cross section in which the first component and the second component are laminated.
(Aspect 7)
7. The non-woven fabric of any of the preceding aspects, wherein the non-heat shrinkable fiber is a single fiber consisting of polypropylene or polyethylene terephthalate.
(Aspect 8)
The nonwoven fabric according to any one of aspects 1 to 7, wherein the mean deviation (SMD) of surface roughness measured on the surface of the nonwoven fabric is 3.6 μm or less.
(Aspect 9)
A heat shrinkable composite fiber comprising a first component and a second component having a melting point Tf ₂ higher than the melting point Tf ₁ of the first component, a temperature of 120 ° C., a time of 15 minutes, and an initial load of 0.018 mN / dtex When the heat-shrinkable composite fiber and the non-heat-shrinkable fiber are combined to 100% by mass with the non-heat-shrinkable fiber having a dry-heat shrinkage of 20% or less measured under the conditions The fibrous web by mixing so that the proportion of the composite fibers becomes 25% by mass or more and 85% by mass or less
Mechanical entanglement treatment is performed on the fiber web to entangle fibers constituting the fiber web,
Performing heat treatment after the confounding process;
Including
In the non-woven fabric obtained after the heat treatment, the heat treatment is performed such that the average value of the dimensional change in the longitudinal direction and the dimensional change in the lateral direction at (Tf ₁ -8) ° C. is 8% to 25%. Do,
Method of manufacturing nonwoven fabric.
(Aspect 10)
In the heat-shrinkable conjugate fiber, the first component contains an ethylene / α-olefin copolymer having a melting point of less than 130 ° C., and the first component is 20% or more of the length of the circumferential surface of the fiber Composite fiber exposed at the length of
The heat treatment is performed at 78 ° C. or more and less than 98 ° C.,
The manufacturing method of the nonwoven fabric of aspect 9.
(Aspect 11)
In the heat-shrinkable conjugate fiber, the first component includes a propylene copolymer copolymerized with ethylene and having a melting point of 130 ° C. or more and 145 ° C. or less, and the first component has a length of the circumferential surface of the fiber Composite fiber exposed at a length of 20% or more,
The heat treatment is performed at 100 ° C. or more and less than 125 ° C.,
The manufacturing method of the nonwoven fabric of aspect 9.
(Aspect 12)
An article for skin contact wherein the nonwoven fabric of any of aspects 1-8 occupies at least a portion of the skin contacting surface.

  The nonwoven fabric of the present invention is soft, exhibits good feel, and is bulky, and therefore, at least one of the skin contacting products of a sanitary product such as a mask and an absorbent product such as a disposable diaper. It is suitable for the member which constitutes the part.

Claims (12)

A crimped conjugate fiber having a three-dimensional crimp, comprising: a first component; and a second component having a melting point Tf ₂ higher than the melting point Tf ₁ of the first component;
A non-heat-shrinkable fiber having a dry heat shrinkage of 20% or less when measured at a temperature of 120 ° C. for 15 minutes and an initial load of 0.018 mN / dtex;
When the mass of the crimped conjugate fiber and the non-heat-shrinkable fiber is 100% by mass, the ratio of the crimpable conjugate fiber is 25% by mass to 85% by mass.
Constituent fibers are entangled,
(Tf 1 _-8) average of longitudinal dimensional change and transverse dimensional change of at ℃ is 25% or less than 8%, the nonwoven fabric.   The nonwoven fabric according to claim 1, wherein the constituent fibers are not heat-bonded to each other.   In the crimped conjugate fiber, the first component contains 50% by mass or more of a propylene copolymer or an ethylene / α-olefin copolymer having a melting point of 145 ° C. or less, and the first component has a circumference of the fiber The nonwoven fabric according to claim 1 or 2, which is a composite fiber exposed at a length of 20% or more with respect to the length of the surface. In the crimped conjugate fiber, the first component contains 50% by mass or more of an ethylene / α-olefin copolymer having a melting point of less than 130 ° C.,
The nonwoven fabric according to claim 3, wherein the ethylene / α-olefin copolymer is a linear low density polyethylene polymerized using a metallocene catalyst.   The nonwoven fabric according to any one of claims 3 or 4, wherein the second component of the crimped conjugate fiber contains 50% by mass or more of polypropylene having a melting point of 150 ° C or more.   The fiber cross section of the crimped conjugate fiber is an eccentric core-in-sheath cross section in which the first component is a sheath component, the second component is a core component, and the center of gravity of the second component is offset from the center of gravity of the fiber. The nonwoven fabric according to any one of claims 1 to 5, which is a side-by-side cross section in which the first component and the second component are pasted together.   The non-woven fabric according to any one of claims 1 to 6, wherein the non-heat-shrinkable fiber is a single fiber composed of polypropylene or polyethylene terephthalate.   The nonwoven fabric according to any one of claims 1 to 7, wherein an average deviation (SMD) of surface roughness measured on the nonwoven fabric surface is 3.6 μm or less. A heat shrinkable composite fiber comprising a first component and a second component having a melting point Tf ₂ higher than the melting point Tf ₁ of the first component, a temperature of 120 ° C., a time of 15 minutes, and an initial load of 0.018 mN / dtex When the heat-shrinkable composite fiber and the non-heat-shrinkable fiber are combined to 100% by mass with the non-heat-shrinkable fiber having a dry-heat shrinkage of 20% or less measured under the conditions The fibrous web by mixing so that the proportion of the composite fibers becomes 25% by mass or more and 85% by mass or less
Mechanical entanglement treatment is performed on the fiber web to entangle fibers constituting the fiber web,
Performing heat treatment after the confounding process;
Including
In the non-woven fabric obtained after the heat treatment, the heat treatment is performed such that the average value of the dimensional change in the longitudinal direction and the dimensional change in the lateral direction at (Tf ₁ -8) ° C. is 8% to 25%. Do,
Method of manufacturing nonwoven fabric. In the heat-shrinkable conjugate fiber, the first component contains an ethylene / α-olefin copolymer having a melting point of less than 130 ° C., and the first component is 20% or more of the length of the circumferential surface of the fiber Composite fiber exposed at the length of
The heat treatment is performed at 78 ° C. or more and less than 98 ° C.,
The manufacturing method of the nonwoven fabric of Claim 9. In the heat-shrinkable conjugate fiber, the first component includes a propylene copolymer copolymerized with ethylene and having a melting point of 130 ° C. or more and 145 ° C. or less, and the first component has a length of the circumferential surface of the fiber Composite fiber exposed at a length of 20% or more,
The heat treatment is performed at 100 ° C. or more and less than 125 ° C.,
The manufacturing method of the nonwoven fabric of Claim 9.   A product for skin contact, wherein the non-woven fabric according to any one of claims 1 to 8 occupies at least a part of the surface in contact with the skin.

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