JP6897325B2 - Non-woven - Google Patents

Description

The present invention relates to a non-woven fabric that is industrially stable, has excellent productivity, and has a good texture, and is particularly preferably used as a non-woven fabric for sanitary materials.

In general, non-woven fabrics for sanitary materials such as disposable diapers and sanitary napkins are required to have excellent texture for comfort when worn. In particular, a good texture is required for a top sheet in which the buttocks of the wearer directly touches the skin and a back seat that is often touched when wearing clothes.

Nonwoven fabrics for sanitary materials are manufactured from materials obtained from fossil resources such as polyester, polyethylene (PE) and polypropylene (PP). Petroleum, which is a fossil resource, is an important raw material for the chemical industry, but there is a concern that it will be depleted in the future. In addition, it emits a large amount of carbon dioxide during the manufacturing process and incineration, resulting in global warming. It invites a series of issues such as. Under these circumstances, with regard to non-woven fabrics for sanitary materials such as disposable diapers and sanitary napkins, the amount of non-woven fabrics for sanitary materials used in Japan is extremely large, exceeding 200,000 tons per year, and is used. After that, 100% of the waste is disposed of, so much attention is being paid to the use of recycled raw materials and materials with low environmental impact.

Nonwoven fabrics for sanitary materials include so-called air-through non-woven fabrics in which short fibers typified by composite fibers made of polyethylene terephthalate (PET) and polyethylene (PE) are sheeted by carding and then self-fused by hot air treatment. Polypropylene spunbonded non-woven fabrics are preferably used.

Air-through non-woven fabric is mainly used as a top sheet as a sanitary material because it has the characteristics of being bulky and excellent in flexibility. In addition, polypropylene spunbonded non-woven fabric is widely used for back seats and side gathers of sanitary materials because of its excellent strength and cost.

On the other hand, the conventional non-woven fabric for sanitary materials uses a raw material derived from petroleum, and a non-woven fabric using a material having a low environmental load, for example, a raw material derived from biomass, has the characteristics required for the non-woven fabric for sanitary materials. The current situation is that they are not satisfied and cannot be applied. Demand for sanitary materials such as disposable diapers and napkins is expected to grow steadily in the future, and there is an urgent need to apply raw materials with low environmental impact to the non-woven fabrics that make up most of them. There is.

Against this background, in order to eliminate the influence of polymerization catalyst residues and the like and to solve the problem of yarn breakage during spinning, a metal salt of an aliphatic carboxylic acid having 12 to 22 carbon atoms is added to polyethylene. It has been proposed to contain 800 ppm or less and 200 ppm or more (see Patent Document 1).

In addition, as a countermeasure against yarn breakage during spinning, friction during air soccer towing, and poor fiber opening, in composite fibers (fibers having a core-sheath structure), ethylene-vinyl acetate copolymer and low-density polyethylene are used as sheath components. It has been proposed to use a mixed resin mixed with a linear higher fatty acid or a metal salt thereof (see Patent Document 2).

Further, as for polyester, a polymer using a glycol derived from a biomass resource as a raw material has been studied (see Patent Document 3). However, polymers using biomass resource-derived glycols have lower heat resistance than fossil resource-derived polymers. For example, polyester is made into chips and then remelted and molded into filaments, films, resins, and the like. When the polymer (polyester) using the glycol derived from biomass resources undergoes a thermal history close to 300 ° C. in the performed process, the thermal decomposition reaction is promoted, so that the polymer becomes yellow, the viscosity decreases, and the molecular weight decreases. As a result, there is a problem that unfavorable phenomena occur in use, such as an increase in stains on the base of the resin molding machine, further generation of foreign substances, and deterioration of the physical properties of the resin molded product.

In particular, in the production of non-woven fabrics for sanitary materials, it is possible to take a means of fineness in order to obtain a good texture, but when a polymer using a conventional biomass resource origin is applied, the spinning stability is improved. At present, it is very low and a non-woven fabric having a fine fineness cannot be obtained. Further, the non-woven fabric for sanitary materials is required to be low cost because it is a disposable product, but from the viewpoint of deterioration of spinnability due to an increase in stains on the base surface, it is not possible to produce the non-woven fabric unless the discharge amount is low. The current situation is that productivity is low and cannot be applied. In addition, whiteness as a feeling of cleanliness is required for sanitary material applications. Therefore, it is not preferable to apply a polymer having low heat resistance and turning yellow due to thermal decomposition. For these reasons, conventional non-woven fabrics using raw materials having a low environmental load cannot be applied to non-woven fabrics for sanitary materials.

Conventionally, a non-woven fabric having a low environmental load, industrially excellent productivity and stability, and an excellent texture at a satisfactory level for being suitably used as a sanitary material has not been obtained at present. ..

Japanese Unexamined Patent Publication No. 1-221514 Japanese Unexamined Patent Publication No. 10-1687294 Japanese Unexamined Patent Publication No. 2009-209145

Therefore, in view of the above problems, an object of the present invention is to provide a non-woven fabric which is industrially excellent in productivity and stability and has a satisfactory level of texture for suitable use as a sanitary material or the like. is there.

Non-woven fabric of the present invention, Ri Do polyethylene and polyester, a composed nonwoven fabric the polyethylene mass ratio 90 / 10-10 / 90 Der Ru fibers of the polyester, the polyethylene plant-derived polyethylene 50 It is a non-woven fabric containing% by mass or more, and in which a saturated fatty acid-based additive is added to the polyethylene so as to satisfy the following conditions A to C.
A. The saturated fatty acid-based additive comprises two or more kinds of saturated fatty acids or saturated fatty acid metal salts having different carbon atoms from among saturated fatty acids or saturated fatty acid metal salts having 12 to 45 carbon atoms.
B. The difference in the number of carbon atoms between the saturated fatty acid or the saturated fatty acid metal salt contained in the saturated fatty acid-based additive is 4 or more.
C. The total amount of the saturated fatty acid-based additive added to polyethylene is 0.1 to 10.0% by mass.

Further, according to a preferable mode of the nonwoven fabric of the present invention, calcium stearate is contained as a component of the saturated fatty acid-based additive.

Further, according to a preferable mode of the nonwoven fabric of the present invention, the polyester contains 1 to 500 ppm of a component derived from 1,2-propanediol and is heat-bonded.

Further, according to a preferable mode of the nonwoven fabric of the present invention, the structure of the cross section of the fiber is any structure selected from the group consisting of a concentric core-sheath structure, an eccentric core-sheath structure and a side-by-side structure. Is.

According to the present invention, it is possible to obtain a non-woven fabric which is industrially excellent in productivity and stability and has an excellent texture at a satisfactory level for use as a sanitary material or the like. Since the viscosity of polyethylene can be adjusted, it is possible to suppress yarn breakage during spinning, and further, the sheet processability is good and the releasability from the roll is good, so that a non-woven fabric having stable performance can be obtained. Further, these effects can be exhibited even when a raw material having a low environmental load is used.

It is a schematic cross-sectional view which illustrates the cross section of the fiber which comprises the nonwoven fabric of this invention. It is a schematic cross-sectional view which illustrates the cross section of the other fiber which constitutes the nonwoven fabric of this invention. It is a schematic cross-sectional view which illustrates the cross section of the other fiber which comprises the nonwoven fabric of this invention.

The non-woven fabric of the present invention is a non-woven fabric composed of fibers made of polyethylene and polyester, and is characterized in that a saturated fatty acid-based additive is added to the polyethylene so as to satisfy the following conditions A to C. It is a non-woven fabric.
A. The saturated fatty acid-based additive comprises two or more kinds of saturated fatty acids or saturated fatty acid metal salts having different carbon atoms from among saturated fatty acids or saturated fatty acid metal salts having 12 to 45 carbon atoms.
B. The difference in the number of carbon atoms between the saturated fatty acid or the saturated fatty acid metal salt contained in the saturated fatty acid-based additive is 4 or more.
C. The total amount of the saturated fatty acid-based additive added to polyethylene is 0.1 to 10.0% by mass.

The non-woven fabric of the present invention preferably contains 50% by mass or more of plant-derived polyethylene.

The non-woven fabric of the present invention preferably contains calcium stearate as a component of the saturated fatty acid-based additive.

The main component of the polyethylene used for the non-woven fabric of the present invention is an ethylene polymer. Ethylene-based polymers include (1) petroleum-based polyethylene synthesized from ethylene obtained by high-temperature thermal decomposition of naphtha, and (2) ethylene obtained by dehydrating vegetable ethanol obtained from sugar cane and the like at a relatively low temperature. Examples thereof include vegetable polyethylene obtained by polymerizing.

In petroleum-based polyethylene, (1) medium-density polyethylene, high-density polyethylene, and (2) ethylene main chain are provided with branching components different from ethylene, such as butene, hexene, 4-methylpentene, heptene, and octene. The copolymerized product is preferable from the viewpoint of yarn strength.

In plant-based polyethylene, (1) poly (ethylene-RAN-butylene) mono-OL, (2) ethylene / 1-hexenkopolymer, (3) butene-ethylene-hexene-polymer, or (4) Any of polyethylene is preferable from the viewpoint of spinning strength. Polyethylene means a polymer having an ethylene-based unit as a repeating unit. By using polyethylene and containing saturated fatty acid-based additives having different carbon atoms, a non-woven fabric having excellent flexibility can be obtained.

In polyethylene, the content of the ethylene-based polymer main component is preferably 70% by mass or more, more preferably 80% by mass or more.

When the polymer of the second component is used with respect to the main component of the ethylene-based polymer, it is preferably used in combination with the petroleum-based polyethylene and the plant-based polyethylene. A small amount of other component polymer may be blended with the ethylene polymer as the main component. Examples of the other component polymer include polyolefin-based polymers having a melting point close to that of polyethylene, poly4-methylpentene, and low-melting-point polyesters and low-melting-point polyamides. However, in order to fully express the characteristics of polyethylene, the ratio of the blended product is preferably 5% by mass or less, more preferably 2% by mass or less.

Further, a pigment for coloring, an antioxidant, a heat-resistant stabilizer and the like may be added to the ethylene polymer.

The density of the plant-based polyethylene used in the present invention is preferably 0.915 to 0.965 g / cm ³ . Further, the density of the petroleum-based polyethylene is preferably 0.930 to 0.965 g / cm ^3, and appropriate crystallinity can be exhibited, and high strength can be achieved.

This is because the density of plant-based polyethylene is low because impurities in the raw material contain a large amount of branched monomer components having 4 or less carbon atoms. However, the strength at the time of spinning is almost the same as that of petroleum-based polyethylene. This seems to be the effect of the length of the main chain and its distribution.

In the case of petroleum-based polyethylene, it is possible to increase the number of branches having 4 or less carbon atoms by polymerization, but those having branches having 6 to 10 carbon atoms are preferable from the viewpoint of controlling the composition distribution. The copolymerization ratio of the comonomer of petroleum-based polyethylene is preferably 0.1 to 3.0 mol%. The copolymerization ratio is more preferably 1.0 mol% or less from the viewpoint of further increasing the strength.
Next, as the saturated fatty acid-based additive, the reason why two or more kinds of saturated fatty acids or saturated fatty acid metal salts having different carbon numbers are used from among the saturated fatty acids having 12 to 45 carbon atoms and the saturated fatty acid metal salts will be described.
Here, the term "when the saturated fatty acid-based additive is composed of two or more saturated fatty acids or saturated fatty acid metal salts having different carbon atoms from among saturated fatty acids and saturated fatty acid metal salts having 12 to 45 carbon atoms" is defined as ( 1) When composed of two or more fatty acids selected from saturated fatty acids having 12 to 45 carbon atoms, or (2) Metal salts of two or more saturated fatty acids selected from metal salts of saturated fatty acids having 12 to 45 carbon atoms Or (3) a mixture of a fatty acid having a different number of carbon atoms and a metal salt of a fatty acid selected from a saturated fatty acid having 12 to 45 carbon atoms and a metal salt of a saturated fatty acid having 12 to 45 carbon atoms. means.

It has been considered that thread breakage occurs due to the poor silk-reeling property of polyethylene during sheet processing, and that sheet defects occur from this as a starting point. However, upon closer examination, it was confirmed that sheet defects occur starting from this thread breakage, but even in the part where the thread breakage does not occur, there is fluffing after the roller threading, and the sheet itself. It turned out that the phenomenon of wrapping around the roll is occurring. This phenomenon is more likely to occur as the linear pressure of the roller is higher, the surface temperature of the roller is higher, and the speed is faster. This occurs even in the portion where the yarn is not broken because the releasability of the yarn with respect to the roll is poor.

There is also a method of applying oil to the surface of the yarn in order to achieve releasability with the roller, but as the fineness of the single fiber decreases, the stickiness of the oil increases, so adjustments such as reducing the amount of application are necessary. is there. However, with this method, it is difficult to uniformly apply a small amount of oil to a large number of yarns at one time during spinning. Further, when oil is applied to the surface of the yarn, the bondability (adhesiveness) between the yarns is inferior.

Therefore, two or more kinds of fatty acids or fatty acid metal salts are melt-kneaded with polyethylene, and the surface texture is changed by one kind of fatty acid or fatty acid metal salt (A) to improve the releasability to rolls, and the other one kind. The viscosity of the ethylene polymer is finely adjusted to the extent that it can be spun with the fatty acid or fatty acid metal salt (B) of the above, and the spinning is stabilized, and the dispersed state of the fatty acid or fatty acid metal salt (A) is controlled to be stable. We have obtained sheet processing performance.

This is because, as will be described later, the fatty acid or the fatty acid metal salt (B) can adjust the crystallization rate at the time of spinning / stretching crystallization of the ethylene polymer.

By containing 0.1% by mass or more and 10% by mass or less of the saturated fatty acid-based additive with respect to polyethylene, it is possible to obtain a non-woven fabric having excellent flexibility, high strength, and excellent sheet processability. ..

By adding 0.1% by mass or more of the saturated fatty acid-based additive, the releasability from the roller during sheet processing becomes good, and sheet defects such as sheet tearing are eliminated. Further, by setting the addition amount to 10% by mass or less, the amount of the saturated fatty acid-based additive present on the yarn surface does not become too large, and the sticky feeling does not become too strong. Further, 0.5% by mass or more and 5.0% by mass or less are more preferable.

When the saturated fatty acid-based additive has 12 or more carbon atoms, the releasability from the roller becomes good. By setting the number of carbon atoms to 45 or less, it is possible to obtain a non-woven fabric that does not have a sticky feeling or a stiff feeling while maintaining the releasability from the roller during sheet processing.

Among ethylene-based polymers, those having a small carbon number are likely to appear on the yarn surface, and those having a large carbon number are considered to be uniformly dispersed.

As a combination of a fatty acid or a fatty acid metal salt capable of more exerting the effect of the present invention, a fatty acid having a relatively short molecular chain having 12 to 16 carbon atoms or a fatty acid metal salt (A) and a molecular chain having 18 to 45 carbon atoms can be used. It is preferable to use two kinds of relatively long fatty acid or fatty acid metal salt (B) in combination. This is because short molecular chain fatty acids or fatty acid metal salts tend to appear on the yarn surface during spinning, and it is difficult to uniformly disperse them in an ethylene polymer. The long molecular chain fatty acid or fatty acid metal salt has a slightly plastic effect on the ethylene polymer, whereby the dispersibility of the short molecular chain fatty acid or fatty acid metal salt (A) can be improved. .. Further, it has an effect of improving the dispersibility of additives such as a colorant and an agent for preventing rough skin. In order to obtain this effect, a combination containing a fatty acid or a fatty acid metal salt (A) and a fatty acid or a fatty acid metal salt (B) having a difference in carbon number of 4 or more is preferable. As long as the difference in carbon number is 4 or more, the difference in carbon number may be 3 or less.

The short-molecular-weight fatty acid or fatty acid metal salt present on the surface of the yarn not only reduces friction during spinning and improves workability, but also improves the balance between moisture permeability / moisture retention and diffuses water. It was also found that the water-absorbing polymer particles can absorb the water-absorbent polymer particles without being affected by the uneven distribution of the water-absorbent polymer particles when the water-absorbing polymer particles are used as a sanitary material. Therefore, it is possible to always give a smooth and comfortable touch until the water absorption limit is reached. The long molecular chain fatty acid or fatty acid metal salt can adjust the viscosity of polyethylene and has the effect of improving the flexibility of polyethylene.

For the purpose of exerting these effects more, it is more desirable that the fatty acid or the fatty acid metal salt has 14 to 45 carbon atoms, and further preferably 14 to 25 carbon atoms. In particular, it is more preferable to add calcium stearate having 18 carbon atoms. Calcium stearate is very preferable from the viewpoint of use as a non-woven fabric for sanitary materials because it has a particularly excellent effect as a lubricant, is inexpensive, is easily available, and is harmless to the human body.

Further, the content-mass ratio of the fatty acid or fatty acid metal salt having the lowest carbon number to the fatty acid or fatty acid metal salt different from the fatty acid is preferably (1-55) :( 99-45) in order to obtain the above effect. By matching with polyethylene as the main component, the above-mentioned effect can be obtained within the range of this ratio. By setting the fatty acid or fatty acid metal salt having a small number of carbon atoms to 55% by mass or less, the amount present on the yarn surface increases, and the sticky feeling can be suppressed. Further, when it is set to 1% by mass or more, a friction reducing effect can be obtained and workability is improved. By setting the content mass ratio of the fatty acid or fatty acid metal salt having a large number of carbon atoms to 99% by mass or less, a friction reducing effect can be obtained and the processability is improved. Further, by setting the content mass ratio of the fatty acid or fatty acid metal salt having a large number of carbon atoms to 45% by mass or more, the effect of improving the dispersibility of the additive or the like can be sufficiently obtained.

As the metal used for the fatty acid metal salt, an alkali metal selected from Li, Na and K, an alkaline earth metal element selected from Be, Mg, Ca and Ba, and an Al and Zn elements are preferable.

In the combination of the saturated fatty acid-based additive having a small carbon number and the saturated fatty acid-based additive having a large carbon number, the fatty acid having a large carbon number is preferably a metal salt having a divalent value or more (Mg, Ca, Ba, Al, Zn). Although the reason is not clear, a metal salt having a divalent value or higher has better dispersibility in itself, and a high-quality non-woven fabric can be obtained without a feeling of gore when it comes into contact with the skin when it is made into a non-woven fabric sheet.

Further, the non-woven fabric of the present invention is a non-woven fabric composed of the fibers made of polyethylene and polyester. It is preferable that the polyester contains 1 to 500 ppm of a component derived from 1,2-propanediol and the non-woven fabric is heat-bonded.

The content of the component derived from 1,2-propanediol in the polyester is more preferably 20 to 400 ppm.

If the content of the component derived from 1,2-propanediol in the obtained polyester is larger than the above range, the heat resistance tends to deteriorate, and if the content is small, the heat resistance improving effect is insufficient. May become.

The content of the component derived from 1,2-propanediol referred to here is the total amount of 1,2-propanediol detected when the polyester is decomposed and analyzed, and is copolymerized in the polymer chain. It represents the total amount of 1,2-propanediol having a structure derived from 1,2-propanediol and 1,2-propanediol mixed between the polymers. That is, the 1,2-propanediol may be partially copolymerized in the polyester main chain, and may be contained in the polyester as a simple substance without copolymerization.

Examples of the dicarboxylic acid and / or an ester-forming derivative thereof used for the polyester used in the present invention include terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid (for example, 2,6-naphthalenedicarboxylic acid), and diphenyldicarboxylic acid (for example). , Diphenyl-4,4'-dicarboxylic acid), oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelli acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid and dodecanedioic acid. Alicyclic dicarboxylic acids such as carboxylic acids, cyclohexanedicarboxylic acids, 1,4-cyclohexanedicarboxylic acids, and 5-sulfoisophthalates (lithium 5-sulfoisophthalate, potassium 5-sulfoisophthalates, and 5-sulfos). Examples thereof include aromatic dicarboxylic acids such as sodium isophthalate and ester-forming derivatives thereof.

The ester-forming derivative means a lower alkyl ester of these dicarboxylic acids, an acid anhydride, an acyl chloride and the like, and for example, a methyl ester, an ethyl ester and a hydroxy ethyl ester are preferably used.

A more preferred embodiment of the dicarboxylic acid and / or ester-forming derivative thereof used in the present invention is terephthalic acid and / or a dimethyl ester thereof.

Further, as the terephthalic acid and / or its dimethyl ester, terephthalic acid derived from a biomass resource or its dimethyl ester can be used. As a method for obtaining terephthalic acid derived from a biomass resource, for example, p-cymene is synthesized from cineole obtained from a plant of the genus Eucalyptus (see Journal of the Japanese Society of Chemistry, (2), P217-219; 1986), and then p-. A method of obtaining terephthalic acid via methylbenzoic acid (see Organic Synthesis, 27; 1947) can be mentioned. As yet another method, there is a method of obtaining terephthalic acid from a flange carboxylic acid and ethylene by a Diels-Alder reaction (see WO2009-064515). The terephthalic acid derived from the biomass resource thus obtained can be further converted into an ester-forming derivative and used.

Examples of the diol used for the polyester used in the present invention include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, cyclohexanedimethanol, and the like. Examples thereof include diethylene glycol, 2-methyl-1,3-propanediol, polyoxyalkylene glycol having a molecular weight of 500 to 20000 (polyester glycol, etc.), and diol components such as bisphenol A-ethylene oxide adduct, among which ethylene glycol is used. It is preferably used. Furthermore, as ethylene glycol, since ethylene glycol derived from biomass resources often contains 1,2-propanediol, it is better to use ethylene glycol derived from biomass resources whose content has been adjusted by purification. This is a preferred embodiment.

Examples of the method for obtaining ethylene glycol derived from a biomass resource include a method for obtaining ethylene glycol from a biomass resource such as corn, sugar cane, wheat or a stem of a crop. These biomass resources are first converted to starch, which is then converted to glucose by water and enzymes, then converted to sorbitol by hydrogenation reaction, and sorbitol continues to be hydrogenated at a constant temperature and pressure in the presence of a catalyst. There is a method of obtaining ethylene sorbitol by purifying it as a mixture of various glycols.

As the polyester used for producing the nonwoven fabric of the present invention, terephthalic acid and / or its dimethyl ester is used as a dicarboxylic acid and / or an ester-forming derivative component thereof (hereinafter, may be abbreviated as a dicarboxylic acid component). Polyester terephthalate obtained by using ethylene glycol as a diol component is preferable, and if it is a polyester copolymer mainly containing an ethylene terephthalate unit, the degree of improvement in heat resistance becomes more remarkable, leading to improvement in spinning stability.

As the copolymerization component of the polyester used in the production of the non-woven fabric of the present invention, a structural unit derived from the following components can be contained. Specifically, for example, aliphatic carboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, pimelli acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid and dodecanedioic acid, and fats such as cyclohexanedicarboxylic acid. Cyclic dicarboxylic acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, 1,4-cyclohexanedicarboxylic acid and isophthalic acid, 5-sulfoisophthalate (5-sulfoisophthalic acid lithium salt, 5-sulfoisophthalic acid) It can contain structural units derived from aromatic dicarboxylic acids (such as potassium salts, and 5-sulfoisophthalic acid sodium salts).

Among them, 5-sulfoisophthalates such as lithium 5-sulfoisophthalate, potassium 5-sulfoisophthalate, and sodium 5-sulfoisophthalate and ester-forming derivatives thereof, and polys having a molecular weight of 500 to 20000. Oxyalkylene glycol is more preferably used. As the polyoxyalkylene glycol, polyethylene glycol is preferable, and polyethylene glycol having a molecular weight of 500 to 10000 is particularly preferably used.

The 5-sulfoisophthalate is preferably copolymerized in an amount of 0.1 to 10 mol% based on the total dicarboxylic acid component constituting the polyester, and the polyoxyalkylene glycol having a molecular weight of 500 to 30,000 is the obtained polyester. It is a preferable embodiment that the copolymer is copolymerized in an amount of 0.1 to 10.0% by mass based on the mass of the above. These copolymerization components may be used alone, but when two or more types are copolymerized in combination, the degree of improvement in heat resistance becomes more remarkable.

The fibers constituting the non-woven fabric for sanitary materials of the present invention are made of polyethylene and polyester, and the mass ratio thereof is preferably 90/10 to 10/90. Sufficient thermal adhesiveness can be obtained by setting the mass ratio of polyethylene to 10% by mass or more. By setting the mass ratio of polyester to 10% by mass or more, it is possible to obtain sufficient bulkiness for use as a non-woven fabric.

1 to 3 are schematic cross-sectional views illustrating a cross section of fibers constituting the nonwoven fabric of the present invention.

FIG. 1 is a schematic cross-sectional view showing a cross section of a concentric core-sheath type composite fiber. In FIG. 1, the centers of the core portion (a) and the sheath portion (b) are the same. Specifically, the concentric core-sheath type composite fiber is composed of a core portion (a) and a sheath portion (b), and the core portion (a) is surrounded by a polymer different from the core portion (a) in the cross section of the fiber. A portion that is arranged so as to be formed and extends in the length direction of the fiber. The sheath portion (b) is a portion that is arranged so as to surround the core portion (a) in the cross section of the fiber and extends in the length direction of the fiber.

FIG. 2 is a schematic cross-sectional view showing a cross section of an eccentric core-sheath type composite fiber. In FIG. 2, the centers of the core portion (a) and the sheath portion (b) are different. Specifically, the eccentric core-sheath type composite fiber is composed of a core portion (a) and a sheath portion (b), and the core portion (a) is at least a polymer different from the core portion (a) in the cross section of the fiber. A portion that is arranged so as to be partially surrounded and extends in the length direction of the fiber. Further, the sheath portion (b) is a portion that is arranged so as to surround at least a part of the core portion (a) in the cross section of the fiber and extends in the length direction of the fiber. The eccentric core-sheath type composite fiber includes an exposed type in which the side surface of the core portion (a) is exposed and a non-exposed type in which the side surface of the core portion (a) is not exposed. In the present invention, a non-exposed eccentric core sheath type composite fiber is preferably used from the viewpoint of spinning stability.

FIG. 3 is a schematic cross-sectional view showing a cross section of the side-by-side type composite fiber. The side-by-side type composite fiber has a structure in which the first component (c) and the second component (d) are bonded together. The joint surface of the two components may be either a straight line or a curved line, and differs depending on the viscosity characteristics of the two components and the discharge rate ratio. The cross section of the fiber may be circular, or may be a modified cross section such as an ellipse.

The average single fiber fineness of the fibers used in the non-woven fabric of the present invention is preferably 0.5 dtex or more and 3.5 dtex or less, more preferably 0.7 dtex or more and 3.2 dtex or less, and further preferably 0.9 dtex or more. It is 2.8 dtex or less. From the viewpoint of spinning stability, the average single fiber fineness is preferably 0.5 dtex or more, and the finer the fineness, the more the bonding points of the fibers as a non-woven fabric, so that the strength is high and the flexibility is good. Since the non-woven fabric of the present invention is particularly preferably used for sanitary materials, the average single fiber fineness is preferably 3.5 dtex or less from the viewpoint of the strength of the non-woven fabric for sanitary materials.
The average single fiber fineness described above can be determined from the diameter of the fiber by microscopic observation of the side surface of the fiber. When the fiber cross section is a deformed cross section, it can be calculated from the ^{fiber cross section A (m 2} ) and the polymer density ρ (g / m ^{3) in the fiber cross section photograph using the following equation.}
-Single fiber fineness (dtex) = A (m ² ) x ρ (g / m ³ ) x 10000 (m)
The nonwoven fabric of the present invention preferably has a basis weight of 3 to 200 g / m ^2. The basis weight is more preferably 5 to 150 g / m ² , and even more preferably 10 to 100 g / m ² . By setting the basis weight in the above range, sufficient flexibility can be obtained.

Further, the apparent density of the nonwoven fabric of the present invention ^{is preferably 0.130 g / cm 3} or less. The apparent density can be calculated by dividing the basis weight by the thickness. The apparent density is more preferably 0.125 g / cm ³ or less, and even more preferably 0.100 g / cm ³ or less. By setting the apparent density in the above range, sufficient bulkiness can be obtained.

Next, an example of the method for producing the nonwoven fabric of the present invention will be described.

The non-woven fabric for sanitary materials of the present invention includes a long-fiber non-woven fabric obtained by a spunbond method or a melt blow method, a short-fiber non-woven fabric obtained by forming a fiber web of short fibers using a card and then performing hot air treatment. Can be adopted. Among them, spunbonded non-woven fabrics are preferably used because they have good thickness uniformity and are industrially highly productive.

In the spunbond method, the raw material resin is melted and spun from the spinneret, then the yarn that has been cooled and solidified is pulled by an ejector, stretched, collected on a moving net, and then made into a non-woven web, and then heat is generated. This is a manufacturing method that requires a bonding process.

As the shape of the spinneret and the ejector, various shapes such as a round shape and a rectangular shape can be adopted. Among them, a combination of a rectangular base and a rectangular ejector is preferably used from the viewpoint that the amount of compressed air used is relatively small and the yarns are less likely to be fused or scratched.

As the composite base for obtaining the cross-sectional shape of the fiber used in the present invention, a composite base such as a concentric core-sheath base, an eccentric core-sheath base, and a side-by-side type base can be used.

The spinning temperature at the time of melting and spinning is preferably 260 to 350 ° C, more preferably 280 to 310 ° C. By setting the spinning temperature within the above range, a stable molten state can be obtained and excellent spinning stability can be obtained.

Polyethylene and polyester (raw materials) are melted and weighed by separate extruders and spun from the spout discharge holes that are supplied to the spun cap.

As a method of cooling the spun long fiber yarn, for example, a method of forcibly blowing cold air on the yarn, a method of naturally cooling at the atmospheric temperature around the yarn, and a method of adjusting the distance between the spinneret and the ejector. Adjustment methods and combinations thereof can be adopted.

Next, the cooled and solidified yarn is towed and stretched by the compressed air ejected from the ejector.

Then, the long fibers are collected on a moving net to form a non-woven web, and the obtained non-woven web is integrated by heat adhesion to obtain a non-woven fabric.

As a method of heat bonding, for example, a heat embossed roll in which a pair of upper and lower roll surfaces are engraved (unevenness), a roll having a flat (smooth) one roll surface and an engraving (concavo-convex part) on the other roll surface. Thermocompression bonding with various rolls such as a thermal embossing roll consisting of a combination with a roll with a part) and a thermal calendar roll consisting of a combination of a pair of upper and lower flat (smooth) rolls, thermal bonding by hot air treatment, and melting by ultrasonic waves. The dress can be used, and each combination can be applied.

Above all, from the viewpoint of strength and wear resistance, as the heat bonding using the embossed roll, the heat bonding using hot air treatment can be preferably adopted from the viewpoint of bulkiness.

In the thermal bonding by the embossed roll, by using a roll having engraving (concave and convex portions) on either the upper or lower side, it becomes difficult to apply pressure to the whole and the texture is not impaired, which is a preferable embodiment.

The embossed adhesive area ratio at the time of heat fusion is preferably 5 to 30%. By setting the bonding area to 5% or more, more preferably 10% or more, it is possible to obtain strength that can be put into practical use as a non-woven fabric. On the other hand, by setting the embossed adhesive area ratio to 30% or less, more preferably 20% or less, a flexible texture can be maintained.

The embossed adhesive area ratio referred to here is the entire non-woven fabric of the portion where the convex portion of the upper roll and the convex portion of the lower roll overlap and come into contact with the non-woven fabric when heat-bonding is performed by a roll having a pair of irregularities. It refers to the proportion that occupies. Further, when heat-bonding to a roll having irregularities by a flat roll, it means the ratio of the convex portion of the roll having irregularities to the entire non-woven fabric of the portion in contact with the non-woven web.

As the shape of the engraving applied to the thermal embossing roll, a shape such as a circle, an ellipse, a square, a rectangle, a parallelogram, a rhombus, a regular hexagon, and a regular octagon can be used.

The surface temperature of the thermal embossed roll is preferably −50 to -1 ° C. with respect to the melting point of the resin having the lowest melting point (hereinafter, may be referred to as a low melting point resin) among the resins used. By setting the surface temperature of the heat embossed roll to -50 ° C or higher, more preferably -30 ° C or higher, and even more preferably -10 ° C or higher with respect to the melting point of the low melting point resin, the fluff can be sufficiently heat-bonded to have strength. It is possible to easily suppress the occurrence.

Further, by setting the surface temperature of the heat embossed roll to -1 ° C. or lower with respect to the melting point of the low melting point resin, it is possible to easily prevent the resins from peeling off due to the melting of the fibers.
Further, the linear pressure of the heat embossing roll at the time of heat bonding is preferably 5 to 50 kgf / cm. By setting the linear pressure to 5 kgf / cm or more, more preferably 10 kgf / cm or more, still more preferably 15 kgf / cm or more, sufficient thermal adhesion can be achieved. On the other hand, by setting the linear pressure to 50 kgf / cm or less, more preferably 40 kgf / cm or less, still more preferably 30 kgf / cm or less, the texture of the non-woven fabric can be maintained by not applying too much stress to the roll. ..

In the case of heat bonding by hot air treatment, the hot air temperature is preferably in the range of the melting point of the low melting point resin + 1 ° C. to + 30 ° C., more preferably in the range of + 1 ° C. to + 15 ° C., and further preferably + 1 ° C. to +10. It is in the range of ° C. Sufficient thermal adhesiveness can be obtained by setting the melting point of the low melting point resin to + 1 ° C. or higher. Further, by setting the hot air temperature to preferably the melting point of the low melting point resin + 30 ° C. or lower, more preferably + 15 ° C. or lower, and further preferably 10 ° C. or lower, curing of the non-woven fabric due to heat can be suppressed and a flexible texture can be obtained. Can be maintained.

The amount of hot air is preferably 2.5 to 5.0 m / sec. By setting the amount of hot air to 2.5 m / sec or more, the non-woven fabric for sanitary materials can be ventilated with hot air, and sufficient adhesiveness can be obtained. On the other hand, by setting the hot air volume to 5.0 m / sec or less, it is possible to suppress web turbulence during heat treatment.

Since the non-woven fabric of the present invention has a very excellent texture, it can be particularly suitably used for top sheets and back sheets of disposable disposable diapers and napkins.

Next, the nonwoven fabric of the present invention and the method for producing the same will be specifically described based on Examples.

(1) Melting point of raw material polymer:
The melting points of the raw material polymers (polyethylene and polyester) were measured using a differential scanning calorimeter DSC-2 manufactured by Perkin Elma Co., Ltd. under the condition of a temperature rise rate of 20 ° C./min, and the extreme value was obtained in the obtained melt endothermic curve. The given temperature was taken as the melting point. Further, in the differential scanning calorimeter, the resin whose melting endothermic curve does not show an extreme value was heated on a hot plate, and the temperature at which the resin was completely melted by microscopic observation was taken as the melting point.

(2) Polyethylene MFR:
The MFR of polyethylene was measured according to JIS K 7210 (1999), and was measured at a temperature of 190 ° C. under a load of 2.16 kg.

(3) Intrinsic viscosity of polyester (IV):
The intrinsic viscosity (IV) of polyester was measured by the following method. 8 g of the sample was dissolved in 100 ml of orthochlorophenol, and the relative viscosity ηr was determined by the following formula using an Ostwald viscometer at a temperature of 25 ° C.
・ Ηr = η / η0 = (t × d) / (t0 × d0)
(Here, η is the viscosity of the polymer solution, η0 is the viscosity of orthochlorophenol, t is the falling time of the solution (seconds), d is the density of the solution (g / cm ³ ), and t0 is the falling time of orthochlorophenol (here). Seconds) and d0 represent the density of orthochlorophenol (g / cm ³ ), respectively.)
Next, the intrinsic viscosity (IV) was calculated from the above relative viscosity ηr by the following formula.
-IV = 0.0242ηr + 0.2634.

(4) Content of 1,2 propanediol in polyester:
Collect 1 g or more of the sample from the non-woven fabric. The collected sample is immersed in an organic solvent to dissolve and remove the polyethylene component. As the organic solvent to be used, 1,2,4-trichlorobenzene may be used as long as it dissolves the polyethylene component. Polyethylene is dissolved and removed with an organic solvent to obtain a polyester component.

Subsequently, a 1000 μg / ml aqueous solution of 1,2-butanediol was prepared and used as an internal standard solution A. 0.1 g of the sample was weighed in a vial, 0.006 ml of the internal standard solution A and 1 ml of aqueous ammonia were added, the mixture was sealed, heated at a temperature of 150 ° C. for 3 hours, and then allowed to cool to a room temperature of 25 ° C. Subsequently, 2 ml of methanol and 2.0 g of terephthalic acid were added, and the mixture was shaken for 15 minutes and centrifuged at 3500 G for 3 minutes. The supernatant was taken out and measured by a gas chromatograph (GC6890 manufactured by Agilent Technologies) under the following setting conditions, and the content was determined using a calibration curve described later.
・ Split ratio: 1/20,
・ Carrier gas flow velocity: 2 mL / min,
・ Inlet temperature: 220 ° C,
・ Injection volume: 1 μL,
・ MS: JEOL SX-102A,
-Monitor ion: m / z 61.0290.

A calibration curve of 1,2-propanediol was prepared by the following procedure. A 1000 μg / ml aqueous solution of 1,2-propanediol was prepared to prepare a standard mother liquor B, and then diluted with a mixed solvent (methanol: water = 2: 1 (mass ratio)) by changing the amount of the standard mother liquor B. Then, 5 kinds of standard solutions C were prepared. An internal standard solution A was added to each solution so as to contain 2.00 μg / ml of 1,2 butanediol as an internal standard. The prepared standard solution C was measured by gas chromatography under the above conditions, and then the peak area ratio of the obtained 1,2-propanediol and the internal standard substance and the 1,2-propanediol in the standard solution C were measured. A calibration curve of 1,2-propanediol was prepared by plotting the concentration of 1,2-propanediol on a graph.

(5) Sediment around the mouthpiece and frequency of thread breakage:
The amount of deposits around the mouthpiece hole 100 hours after the fiber was spun was observed using a long focus microscope. In addition, the number of yarn breaks per ton of production was counted and judged according to the following criteria. The judgments of ◎ and ○ were passed, and the judgment of × was rejected.
⊚: The number of yarn breaks is 0.5 times / ton or less in a state where almost no deposits are observed and production is possible.
◯: Although some deposits are observed, production is possible, and the number of thread breaks is 2.0 times / ton or less.
X: A state in which deposits are observed and thread breakage occurs frequently, and the number of thread breakages is more than 2.0 times / ton.

(6) Average fiber diameter of single fiber:
The non-woven fabric was observed with a scanning electron microscope (VE-7800 type manufactured by SEM KEYENCE CORPORATION) at a magnification of 500, and the diameters of 50 randomly selected single fibers were measured. This was performed at three locations, the diameters of a total of 150 single fibers were measured, and the average value was calculated by rounding off to the nearest whole number. When the fiber cross section is a deformed cross section, the cross section of the single fiber was first measured, and the average fiber diameter of the single fiber was obtained by calculating the diameter when the cross section was regarded as a circle.

(7) Average fineness of single fiber:
From the fiber diameter obtained above and the solid density of the resin used, the mass per 10,000 m in length was taken as the single fiber fineness, and the second decimal place was rounded off.

(8) Non-woven fabric basis weight:
The basis weight of the non-woven fabric is based on 6.2 "Mass per unit area" of JIS L1913 (2010), and 3 test pieces of 20 cm x 25 cm are collected per 1 m of sample width, and each mass in the standard state (mass in standard state). g) was weighed and the average value was ^{expressed as mass per 1 m 2} (g / m ² ).

(9) Thickness of non-woven fabric:
The thickness of the non-woven fabric was measured according to JIS L 1908 (2010). Prepare a presser foot with an area of 2500 mm2. For a test piece having a size of 1.75 times or more the diameter of the presser foot, apply a pressure of 2 kPa for a certain period of time, and then measure the thickness. The average value for 10 test pieces was calculated, and the value was used as the thickness.

(10) Apparent density of non-woven fabric:
The apparent density of the non-woven fabric was calculated from the measured basis weight and thickness of the above-mentioned non-woven fabric. It was evaluated that the lower this value was, the better the bulkiness was.

(11) Sensory evaluation of non-woven fabric tactile sensation (flexibility, silky sensation, rugged sensation)
As a sensory evaluation of the non-woven fabric tactile sensation, flexibility, silky sensation, and ruggedness were scored according to the following criteria. This was performed by 10 people, and the average was evaluated as the texture of the non-woven fabric. It was judged that the higher the average value of each, the better the feel of the non-woven fabric, and a score of 4.0 or higher was passed.

<Flexibility>
5 points: Soft 4 points: Between 5 points and 3 points 3 points: Normal 2 points: Between 3 points and 1 point 1 point: Hard <Smooth feeling>
5 points: Smooth 4 points: Intermediate between 5 points and 3 points 3 points: Normal 2 points: Intermediate between 3 points and 1 point 1 point: Rough <Roughness>
5 points: No stiff feeling 4 points: Intermediate between 5 points and 3 points 3 points: Normal 2 points: Intermediate between 3 points and 1 point 1 point: Non-woven fabric processability, (roll wrapping (pulling) (Hanging condition))
The non-woven fabric was run at 20 m / min for 5 minutes using a rubber nip roller. The state of the roll deposits and the non-woven fabric at this time was observed, and points were given according to the following criteria to determine workability (points). A score of 3 or higher was passed.

5 points: There are no fiber deposits on the roll, and no fluff or tear is seen on the non-woven fabric.

4 points: There are fiber deposits on the roll, but no fluff or tear is seen on the non-woven fabric.

3 points: There are fiber deposits on the roll and fluff on the non-woven fabric, but no tears are seen.

2 points: There are fiber deposits on the roll, fluff on the non-woven fabric, and tears.

1 point: The non-woven fabric wraps around the roll due to the tearing of the non-woven fabric.
(Example 1)
(Polyethylene raw material)
Polyethylene (vegetable) with MFR of 30 g / 10 min, calcium tetradecanoate (14 carbon atoms) and calcium stearate (18 carbon atoms) are each crushed with a hammer mill to 1 mm or less, and additives to polyethylene (calcium tetradecanoate and steer). The content of calcium phosphate (mass ratio 1: 3) was weighed to be 0.3% by mass, uniformly mixed with a Henschel mixer, and used as a polyethylene raw material.

(Polyester raw material)
Polyester chips (IV: 0.65) obtained from polycondensation of biomass resource-derived ethylene glycol (refined product, 1,2-propanediol content: 110 ppm) and dimethyl terephthalate were used as polyester raw materials.

(Spinning and collection of textile webs)
Using the above polyethylene raw material as a sheath component and the above polyester raw material as a core component, they are melted by separate extruders and weighed so that the mass ratio of the sheath component to the core component is 50:50. A core-sheath composite fiber was spun from a core-sheath type spinneret having a spinning temperature of 295 ° C. and a hole diameter of 0.55 mm at a single-hole discharge rate of 0.60 g / min. The spun core-sheath type composite fiber was cooled and solidified by applying cooling air, passed through an ejector, spun from the ejector at a spinning speed of 4000 m / min, and collected as a fiber web on a moving net conveyor. At the time of spinning, almost no deposits on the surface of the base were observed, almost no yarn breakage occurred, and the product was in a ready-to-produce state.

(Thermal adhesion)
Subsequently, the resulting fibrous web was subjected to linear pressure using a pair of upper and lower embossed rolls consisting of an upper roll engraved with a metal polka dot pattern and a flat lower roll made of metal with a bonding area of 10%. Was 20 kgf / cm and heat-bonded at a heat-bonding temperature of 90 ° C. to obtain a non-woven fabric having a ^{grain size of 20 g / m 2.} The polyethylene component of the obtained non-woven fabric was removed, and the content of 1,2-propanediol contained in the polyester was measured and found to be 25 ppm. The obtained evaluation results are shown in Table 1.
(Example 2)
(Polyethylene raw material)
Polyethylene consisting of poly (ethylene-RAN-butylene) mono-OL (vegetable) with MFR of 30 g / 10 min, calcium tetradecanoate (14 carbon atoms), calcium hexadecanoate (16 carbon atoms) and calcium stearate (18 carbon atoms) Is crushed with a hammer mill to 1 mm or less, and the content of the mosquito additive (calcium tetradecanoate, calcium hexadecanoate and calcium stearate, mass ratio 1: 1: 3) with respect to polyethylene is 0.5% by mass. It was weighed, uniformly mixed with a Henschel mixer, and used as a polyethylene raw material.

(Polyester raw material)
The same raw material as in Example 1 was used.

(Spinning and collection of textile webs)
The fiber web was collected in the same manner as in Example 1. At the time of spinning, almost no deposits on the surface of the base were observed, almost no yarn breakage occurred, and the product was in a ready-to-produce state.

(Thermal adhesion)
A non-woven fabric having a basis weight of 20 g / m ^{2 was obtained in the same manner as in Example 1.} The obtained evaluation results are shown in Table 1.
(Example 3)
(Polyethylene raw material)
The same raw material as in Example 2 was used.

(Polyester raw material)
The same raw material as in Example 1 was used.

(Spinning and collection of textile webs)
The fiber webs were collected in the same manner as in Example 1 except that the spinneret had an eccentric core sheath type. At the time of spinning, almost no deposits on the surface of the base were observed, almost no yarn breakage occurred, and the product was in a ready-to-produce state.

(Thermal adhesion)
A non-woven fabric having a basis weight of 20 g / m ^{2 was obtained in the same manner as in Example 1.} The obtained evaluation results are shown in Table 1.
(Example 4)
(Polyethylene raw material)
The same raw material as in Example 2 was used.

(Polyester raw material)
Polyester chips (IV: 0.65) obtained from polycondensation of fossil resource-derived ethylene glycol in which 1,2-propanediol was not detected (less than 15 ppm) and dimethyl terephthalate were used as polyester raw materials.

(Spinning and collection of textile webs)
The fiber web was collected in the same manner as in Example 1. Although some deposits on the base surface were observed during spinning, there were few yarn breaks and the yarn was ready for production.

(Thermal adhesion)
A non-woven fabric having a basis weight of 20 g / m ^{2 was obtained in the same manner as in Example 1.} The obtained evaluation results are shown in Table 1.
(Comparative Example 1)
(Polyethylene raw material)
Polyethylene (petroleum-based) with an MFR of 30 g / 10 min and sodium decanoate (10 carbon atoms) are each crushed with a hammer mill to 1 mm or less, and the content of the additive (sodium decanoate) with respect to polyethylene is 0.3% by mass. Weighed so as to be, uniformly mixed with a Henschel mixer, and used as a polyethylene raw material.

(Polyester raw material)
The same raw material as in Example 4 was used.

(Spinning and collection of textile webs)
The fiber web was collected in the same manner as in Example 1. Although some deposits on the base surface were observed during spinning, there were few yarn breaks and the yarn was ready for production.

(Thermal adhesion)
A non-woven fabric having a basis weight of 20 g / m ^{2 was obtained in the same manner as in Example 1.} The obtained evaluation results are shown in Table 1.
(Comparative Example 2)
(Polyethylene raw material)
Polyethylene (petroleum-based) with an MFR of 30 g / 10 min and calcium stearate (18 carbon atoms) are each crushed with a hammer mill to 1 mm or less, and the content of the additive (sodium decanoate) with respect to polyethylene is 0.3% by mass. Weighed so as to be, uniformly mixed with a Henschel mixer, and used as a polyethylene raw material.

(Polyester raw material)
The same raw material as in Example 4 was used.

(Spinning and collection of textile webs)
The fiber web was collected in the same manner as in Example 1. Although some deposits on the base surface were observed during spinning, there were few yarn breaks and the yarn was ready for production.

(Thermal adhesion)
A non-woven fabric having a basis weight of 20 g / m ^{2 was obtained in the same manner as in Example 1.} The obtained evaluation results are shown in Table 1.

In Examples 1 to 3 of the present invention, in addition to being composed of raw materials having a low environmental load, two or more kinds of saturated fatty acids or saturated fatty acid metal salts having 12 to 45 carbon atoms having different carbon atoms in polyethylene are used. Since it contains an additive consisting of saturated fatty acid or saturated fatty acid metal salt, it has excellent sheet texture and bulkiness, and is very suitable for use as a non-woven fabric for sanitary materials. Met.

Since Comparative Examples 1 and 2 contained only one type of additive, the sheet feel was inferior.

(A): Core portion (b): Sheath portion (c): First component (d): Second component

Claims (4)

Ri Do polyethylene and polyester, wherein a polyethylene non-woven fabric constituted by a mass ratio of 90 / 10-10 / 90 Der Ru fibers of the polyester, the polyethylene comprises a plant-derived polyethylene least 50 wt% , A non-woven fabric obtained by adding a saturated fatty acid-based additive to the polyethylene so as to satisfy the following conditions A to C.
A. The saturated fatty acid-based additive comprises two or more kinds of saturated fatty acids or saturated fatty acid metal salts having different carbon atoms from among saturated fatty acids or saturated fatty acid metal salts having 12 to 45 carbon atoms.
B. The difference in the number of carbon atoms between the saturated fatty acid or the saturated fatty acid metal salt contained in the saturated fatty acid-based additive is 4 or more.
C. The total amount of the saturated fatty acid-based additive added to polyethylene is 0.1 to 10.0% by mass. The nonwoven fabric according to claim 1, wherein calcium stearate is contained as a component of the saturated fatty acid-based additive. The nonwoven fabric according to claim 1 or 2 , wherein the polyester contains 1 to 500 ppm of a component derived from 1,2-propanediol and is heat-bonded. The non-woven fabric according to any one of claims 1 to 3 , wherein the fiber cross section has any one of a concentric core-sheath structure, an eccentric core-sheath structure, and a side-by-side structure.

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