Non-woven fabric and method for forming same

Abstract

The present invention provides a non-woven fabric comprising a spunbond non-woven layer comprising spunbond fibers wherein the spunbond fibers are two-component spunbond fibers each comprising a first component and a second component wherein the first component comprises polylactic acid and the second component comprises polylactic acid. The first component comprises polylactic acid and a polybutylene succinate-based polyester, and wherein the first component is present in an amount ranging from 50 to 80% by weight and the second component is present in an amount ranging from 20 to 50% by weight, both amounts being based on the total weight of each bi-component spunbond fiber, and wherein the second component comprises polylactic acid and a polybutylene succinate-based polyester, and wherein the first component is present in an amount ranging from 50 to 80% by weight, and the second component is present in an amount ranging from 20 to 50% by weight, both amounts being based on the total weight of each multi-component spunbond fiber, both amounts being based on the total weight of each bi-component spunbond fiber. The amount of the poly (butylene succinate)-based polyester is in the range of 0.2-5% (by weight). In addition, the invention also provides a method for preparing the non-woven fabric and an absorption product comprising the non-woven fabric.

Description

Technical Field

[0001] The present invention relates to a nonwoven fabric, a method for preparing the nonwoven fabric, and an absorbent product comprising the nonwoven fabric. Background Art

[0002] Nonwoven fabrics are used in a variety of applications, such as apparel, disposable medical products, diapers, personal hygiene products, etc. New products developed for these applications have demanding performance requirements, including comfort, fit to the body, freedom of body movement, good softness and drape, sufficient tensile strength and durability, and resistance to surface abrasion, pilling or fuzzing. Therefore, nonwoven fabrics used in these types of products must be designed to meet these performance requirements.

[0003] Traditionally, such nonwoven fabrics are made from thermoplastic polymers, such as polyester, polystyrene, polyethylene and polypropylene. These polymers are generally very stable and can remain in the environment for a long time. However, there has recently been a trend to develop articles and products that are considered to be environmentally friendly and sustainable. As part of this trend, it has been desired to produce eco-friendly products that include increased sustainable content to reduce the content of petroleum-based materials. Therefore, there is currently a need for nonwoven fabrics made from sustainable and degradable polymers, which are preferably derived from renewable resources.

[0004] Polylactic acid or polylactide based polymers (PLA) offer a cost-effective route to sustainable content spunbond nonwovens that can be easily converted into consumer products. Polylactic acid (PLA) is made from plant renewable feedstocks, such as sugar or cellulose from food crops such as corn, sugar beets, sugar cane and wheat. Polylactic acid has the advantage of being compostable and will dissolve into carbon dioxide, biomass and water. Additionally, polylactic acid is recyclable. Polylactic acid is primarily formed from the monomer lactic acid and the cyclic diester lactide. Polylactic acid is typically formed by ring-opening polymerization using a metal catalyst such as, for example, tin octoate. Another method of forming polylactic acid involves direct condensation of lactic acid monomers.

[0005] In order to fully obtain the cost-effectiveness advantage of PLA-based consumer products, PLA must be converted into nonwovens at a very high speed, then converted into final consumer products, while minimizing waste to greatest extent. However, due to the tendency of static electricity generation and accumulation on the fiber with PLA polymer on the surface, it is difficult to combine spinning, web-forming and bonding steps at a very high speed, which is required for the economically attractive production of spunbonded PLA with optimal fabric properties. In addition, when using 100% PLA fiber, lower bonding temperature is required to prevent fiber from sticking to calendering roller. Lower bonding temperature can cause poor fabric properties, such as lower tensile strength and poor elongation, and therefore can not make full use of the potential of this polymer. In addition, the electrostatic charge of 100% PLA fiber during spinning and processing also can cause fiber to stick to calendering roller. In order to overcome these shortcomings, nonwoven fabrics with fibers have been developed, and these fibers have a sheath / core bicomponent structure, wherein PLA is present in the core, and synthetic polymers such as polypropylene are located in the sheath. An example of such a nonwoven fabric is described in U.S. Patent No. 6,506,873. The presence of such synthetic polymers in the sheath provides the necessary properties for the high-speed commercial production of nonwoven fabrics including PLA. Although commercial production of nonwoven fabrics including PLA and synthetic polymers in the sheath is possible, this solution cannot be extended far enough because the industry (and its consumers) are seeking complete sustainability, so nonwoven fabrics are preferably 100% PLA. In addition, JP2008208483A discloses a carded nonwoven web made of shorter staple fibers with a core / sheath configuration, wherein the core component includes a first copolymer of L-lactic acid and D-lactic acid, and the sheath component includes a second copolymer of polyalkylene succinate and L-lactic acid, in which the L-lactic acid is only present in a small amount. Although such carded nonwovens may be attractive from a biodegradability perspective, they are bulky and soft and exhibit poor mechanical properties in terms of tensile strength and elongation. In addition, their basis weight is relatively high and therefore unattractive. As an alternative to the two-component approach, and also to overcome these processing issues, the use of additives such as fatty acid salts has been suggested. Although this approach shows advantages in terms of improved processing and final fabric properties, it also has many associated disadvantages. It requires an additional processing step to provide the aliphatic sulfonic acid; aliphatic sulfonic acid is an environmentally unfriendly compound derived from petrochemicals that is neither sustainable nor biodegradable; and the use of aliphatic sulfonic acid increases the overall processing cost. Simply replacing PLA with other biopolymers such as polybutylene succinate (PBS) is not a viable alternative as they are not available in the necessary commercial quantities, would come with a high price and make the final fabric too expensive, and their spinning and processing properties are very poor. Therefore, there remains a need for fabrics comprising PLA that exhibit improved mechanical properties in terms of tensile strength and elongation and that can be used in absorbent articles such as diapers and wipes and that address the disadvantages associated with the above-mentioned alternative approaches. Summary of the invention

[0006] Surprisingly, it has been found in accordance with the present invention that the addition of a small amount of polybutylene succinate-based polyester to one of the PLA-based components of a multicomponent spunbond fiber significantly improves the mechanical properties of the nonwoven in terms of tensile strength and elongation.

[0007] Accordingly, the present invention relates to a nonwoven fabric comprising a plurality of multicomponent spunbond fibers bonded together to form a nonwoven web, the multicomponent spunbond fibers comprising a first component and a second component, wherein the first component comprises a single polymer composition and the second component comprises a polymer blend composition, wherein the single polymer composition comprises polylactic acid and the polymer blend composition comprises polylactic acid and polybutylene succinate-based polyester, wherein the first component is present in an amount ranging from 50-80% by weight and the second component is present in an amount ranging from 20-50% by weight, both amounts being based on the total weight of each multicomponent spunbond fiber, and wherein the amount of polybutylene succinate-based polyester is in the range of 0.2-5% by weight based on the total weight of each multicomponent spunbond fiber.

[0008] The present nonwoven fabric has the advantage of exhibiting a significant increase in tensile strength and elongation in both the longitudinal and transverse directions compared to the same nonwoven fabric that does not include a small amount of polybutylene succinate-based polyester. For example, the present nonwoven fabric can exhibit at least a 50% increase in tensile strength in both the longitudinal and transverse directions compared to the same nonwoven fabric that does not include a small amount of polybutylene succinate-based polyester.

[0009] The increase in tensile strength allows the application of nonwovens with low basis weights, which is beneficial for example for face and back fabrics. In addition, more open bonding patterns can be used without loss of mechanical properties and improve comfort properties such as softness and drape. The present nonwovens particularly exhibit high wet strength, making them most suitable for use in wet wipes.

[0010] In addition, the increase in elongation allows the nonwoven to be used in applications where elongation is important, such as waist carriers, back ears, and side panels. It also allows post-mechanical processing, such as ring rolling, embossing, and perforation. The present invention provides a nonwoven fabric, a sustainable composite material comprising the nonwoven fabric, and a sustainable product comprising the nonwoven fabric and / or the composite material. The present invention is applicable to a spunbond nonwoven fabric comprising a plurality of multicomponent fibers bonded to one another to form a cohesive web, wherein a polymer blend composition is present at the surfaces of the plurality of fibers.

[0011] The polybutylene succinate-based polymer is present in the multicomponent spunbond fibers in a small amount, i.e., 0.2-5% by weight, based on the total weight of each multicomponent spunbond fiber. The polybutylene succinate-based polyester is preferably present in the multicomponent spunbond fibers in an amount ranging from 0.2-3.5% by weight, more preferably in a range of 0.2-2.5% by weight, even more preferably in a range of 0.2-2.0% by weight, and most preferably in an amount ranging from 0.2-1.5% by weight, based on the total weight of each multicomponent spunbond fiber.

[0012] The polybutylene succinate-based polyester is suitably present in an amount ranging from 1 to 10 wt %, preferably in an amount ranging from 1 to 7 wt %, more preferably in an amount ranging from 1 to 5 wt %, even more preferably in an amount from 1 to 4 wt %, most preferably in an amount from 1 to 3 wt %, based on the total weight of the second component. The polylactic acid is suitably present in an amount ranging from 90 to 99 wt %, preferably in an amount ranging from 93 to 99 wt %, more preferably in an amount ranging from 95 to 99 wt %, even more preferably in an amount ranging from 96 to 99 wt %, most preferably in an amount ranging from 97 to 99 wt %, based on the total weight of the second component. Preferably, the plurality of multicomponent spunbond fibers include bicomponent spunbond fibers. The bicomponent spunbond fibers may have a core / sheath configuration or a side-by-side configuration. Preferably, the bicomponent spunbond fibers have a core / sheath configuration. In the case where the bicomponent spunbond fibers have a core / sheath configuration, the first component corresponds to a core component comprising a single polymer composition, and the second component corresponds to a sheath component comprising a polymer blend composition. The core-sheath bicomponent spunbond fibers may have a symmetrical core-sheath configuration or an eccentric core-sheath configuration, preferably a symmetrical core / sheath configuration. The first component may include a first grade of PLA, and the second component may include a second grade of PLA, wherein the first grade and the second grade are different. Preferably, in the first component and the second component, the same grade of PLA is used.

[0013] The nonwoven fabric according to the present invention and the sustainable composite material comprising the nonwoven fabric can be used in a variety of applications, including diapers, feminine care products, wipes products and incontinence products. Preferably, the nonwoven fabric is used in diapers and wipes products, more preferably in wipes products. For the purposes of this application, the following terms shall have the following meanings: The term "fiber" may refer to fibers of finite length or filaments of infinite length.

[0014] As used herein, the term "single polymer composition" refers to a polymer composition formed from only one type of polymer (PLA in this case). This does not exclude a single polymer composition comprising two different PLAs. Furthermore, this does not exclude additives added for color, antistatic properties, lubricity, hydrophilicity, liquid repellency, etc.

[0015] As used herein, the term "polymer blend composition" refers to a polymer composition formed by a blend including two or more different types of polymers (in this case at least PLA and a polybutylene succinate-based polymer). Of course, this does not exclude polymer blend compositions to which additives have been added for color, antistatic properties, lubricity, hydrophilicity, liquid repellency, etc. In addition, the polymer blend may additionally include other polymers such as polyhydroxyalkanoates (PHA), poly-3-hydroxybutyrate copolymers (P3HB), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), etc.

[0016] As used herein, the term "multicomponent" refers to a fiber (e.g., a bicomponent fiber) comprising two components, wherein the two components are extruded from different extruders. Single polymer compositions and polymer blend compositions are preferably arranged in substantially constant positioned different regions across the cross section of the fiber. These components can be arranged in any desired configuration, such as a sheath-core configuration, a side-by-side configuration, a pie-shaped configuration, an island-in-the-sea configuration, etc. Preferably, the multicomponent spunbond fibers have a core / sheath configuration or a side-by-side configuration. More preferably, the bicomponent spunbond fibers have a core / sheath configuration. The core / sheath configuration can be a symmetrical core / sheath configuration or an eccentric core / sheath configuration, preferably a symmetrical core / sheath configuration. Various methods for forming multicomponent fibers are described in U.S. Pat. Nos. 4,789,592 to Taniguchi et al. and 5,336,552 to Strack et al., 5,108,820 to Kaneko et al., 4,795,668 to Kruege et al., 5,382,400 to Pike et al., 5,336,552 to Strack et al., and 6,200,669 to Marmon et al.

[0017] As used herein, the terms "nonwoven fabric", "nonwoven web" and "nonwoven fabric" refer to a structure or a web of material that is not formed using a weaving or knitting process, and whose structure is formed by individual fibers or threads interlaced, but not in an identifiable repeating pattern. In the past, nonwoven webs have been formed by various conventional processes, such as, for example, meltblowing, spunbonding, and staple fiber carding.

[0018] As used herein, the term "meltblowing" refers to a process in which fibers are formed by extruding a molten thermoplastic material through a plurality of fine, usually circular die capillaries into a high velocity gas (e.g., air) stream, which attenuates the molten thermoplastic material and forms fibers, which may be as thin as microfiber diameters. Thereafter, the meltblown fibers are carried by the gas stream and deposited on a collecting surface to form a random meltblown fiber web. This process is disclosed, for example, in U.S. Pat. No. 3,849,241 to Buntin et al.

[0019] As used herein, the term "machine direction" or "MD" refers to the direction of travel of a nonwoven web during manufacture.

[0020] As used herein, the term "cross direction" or "CD" refers to the direction perpendicular to the machine direction and extending transversely across the width of a nonwoven web.

[0021] As used herein, the term "spunbond" refers to a method that involves extruding a molten thermoplastic material as fibers from a plurality of fine, usually circular capillaries of a spinneret, and then mechanically or pneumatically attenuating and stretching the fibers. Spunbond fibers are continuous fibers compared to shorter staple fibers. Therefore, spunbond fibers are much longer than staple fibers. The fibers are deposited on a collecting surface to form a substantially continuous web of randomly arranged fibers that can then be bonded together to form a bonded nonwoven fabric. The production of spunbond nonwoven webs is shown in various patents, such as, for example, U.S. Patent Nos. 3,338,992; 3,692,613; 3,802,817; 4,405,297; and 5,665,300. In general, these spunbond processes involve extruding fibers from a spinneret, quenching the fibers using air flow to accelerate solidification of the molten fibers, drawing the fibers by applying a drawing tension (either by entraining the fibers pneumatically in an air stream, or mechanically by winding the fibers around mechanical drawing rolls), depositing the drawn fibers onto a collecting surface to form a web, and bonding the loose fiber web into a nonwoven fabric. Bonding can be any thermal or chemical bonding process, such as through-air bonding or thermal point bonding.

[0022] As used herein, the term "thermal point bonding" involves passing the material to be bonded, such as one or more webs, between a heated calendar roll and an anvil roll. The calendar roll is typically patterned so that the fabric is bonded at discrete point bond locations rather than across its entire surface.

[0023] As used herein, the term "through air bonding" refers to a method in which hot air is used to fuse fibers at the surface of a nonwoven web and optionally within the nonwoven web. The hot air can be blown through the web in an oven or drawn through the web as it passes through a porous drum due to the formation of a vacuum. The temperature of the hot air can be high enough to melt and / or fuse the second component (e.g., sheath component) of a multicomponent fiber (e.g., bicomponent fiber) without melting the first component (e.g., core component) of the multicomponent fiber. The hot air can also cause curling of the multicomponent fiber (e.g., bicomponent fiber).

[0024] As used herein, the term "polymer" generally includes, but is not limited to, homopolymers, copolymers, such as, for example, block, graft, random and alternating copolymers, terpolymers, etc., and blends and modifications thereof. In addition, unless otherwise specifically limited, the term "polymer" shall include all possible geometric configurations of the material, including isotactic, syndiotactic and random symmetries.

[0025] As used herein, the term "composite material" may be a structure comprising two or more layers, such as a film layer and a fiber layer or multiple fiber layers molded together. According to certain embodiments of the present invention, two layers of a composite structure may be bonded together such that a majority of their common XY plane interface is bonded together.

[0026] The present nonwoven fabrics include multi-component spunbond fibers, which include a first component and a second component, wherein both components include polylactic acid and the second component additionally includes a small amount of polybutylene succinate-based polyester. These nonwoven fabrics exhibit improvements in tensile strength and elongation.

[0027] A variety of different PLA resins may be used in accordance with the present invention.

[0028] The PLA resin should have the appropriate molecular properties for spinning in a spunbond process. Suitable examples of PLA resins include those supplied by NatureWorks LLC, Minnetonka, Minnesota 55345, such as grades 6752D, 6100D, and 6202D, which are believed to be produced in accordance with the teachings of Gruber et al., U.S. Pat. Nos. 5,525,706 and 6,807,973. Other examples of suitable PLA resins may include L130, L175, LX530, and LX175, all from Corbion, Arkelsedijk 46, 4206 AC, Gorinchem, The Netherlands.

[0029] Preferably, the nonwoven fabric according to the present invention is substantially free of synthetic polymer components, such as petroleum-based materials and polymers.

[0030] According to the first component and the second component of the multi-component fiber of the present invention, both can include one or more additional additives. For example, in such embodiments, the additives can include at least a colorant, a softener, a slip agent, an antistatic agent, a lubricant, a hydrophilic agent, a liquid repellent, an antioxidant, etc. or any combination thereof.

[0031] In one embodiment, the PLA polymer of the sheath component can be the same PLA polymer as the core component. In other embodiments, the PLA polymer of the sheath component can be a different PLA polymer than the core component.

[0032] The melt flow rate (MFR) of the polylactic acid material to be used in the present invention is suitably less than 100 g / 10 min. The MFR of polylactic acid is determined using ASTM test method D1238 (210° C., 2.16 kg). Preferably, the melt flow rate of the polylactic acid material is in the range of 5-90 g / 10 min, more preferably in the range of 10-85 g / 10 min, even more preferably in the range of 15-45 g / 10 min.

[0033] According to the present invention, both the first component and the second component of the multicomponent spunbond fibers may include a mixture of different polylactic acids.

[0034] Preferably, the first component of the multicomponent spunbond fibers comprises only one type of PLA. Preferably, the second component of the multicomponent spunbond fibers comprises only one type of PLA. Preferably, both the first component and the second component comprise only one type of PLA, wherein the PLA in the two components is the same.

[0035] Suitably, the weight average molecular weight of the PLA to be used is in the range of 100,000-300,000 Daltons, preferably in the range of 150,000-250,000 Daltons.

[0036] The PLA to be used according to the present invention may have a melting point ranging from 125-180° C. For example, the PLA in the sheath component may have a melting point ranging from 125-135° C., and the PLA in the core component may have a melting point ranging from 155-180° C.

[0037] Furthermore, different PLAs can have different weight percentages of the D isomer. For example, the PLA in the sheath component can have a weight percentage of the D isomer up to and including 10 weight percent, and the PLA in the core component can have a weight percentage of the D isomer in the range of 90-100 weight percent.

[0038] For example, the D isomer percentage of the polylactic acid that the PLA that the core component includes has can be lower than the D isomer percentage of the PLA polymer used in the sheath component.The PLA polymer with lower D isomer percentage will show higher stress induced crystallization degree during spinning, and the PLA polymer with higher D isomer percentage will keep the higher state of amorphous degree during spinning.The higher sheath component of amorphous degree will promote bonding, and the core that shows higher crystallinity will provide strength for fiber, thereby provides strength for final bonded web.In a specific embodiment, Nature Works PLA grade PLA 6752 with 4%D isomer can be used as sheath, and NatureWorks grade 6202 with 2%D isomer can be used as core component.

[0039] The present nonwoven fabric may suitably have a basis weight in the range of 5-150 grams per square meter (gsm). In some embodiments, the present nonwoven fabric may have a basis weight in the range of 8-100 gsm. Preferably, the present nonwoven fabric has a basis weight of less than 50 gsm. Preferably, the basis weight of the nonwoven fabric is in the range of 10-50 gsm, more preferably in the range of 10-30 gsm, and most preferably in the range of 10-25 gsm. The nonwoven fabric suitably has an area shrinkage of less than 5%, preferably less than 2%.

[0040] The polybutylene succinate-based polyester to be used according to the present invention may be polybutylene succinate (PBS) or polybutylene succinate adipate (PBSA). Suitably, a polybutylene succinate homopolymer or a polybutylene succinate copolymer is used. Preferably, a polybutylene succinate homopolymer is used. According to the present invention, the polymer blend composition of the second component of the bicomponent spunbond fiber may also include a mixture of different polybutylene succinates or a mixture of polybutylene succinate and polybutylene succinate adipate. Preferably, the polymer blend composition includes only one type of polybutylene succinate-based polyester, preferably polybutylene succinate. Polybutylene succinate is a compostable aliphatic polyester that can be prepared by polycondensation of succinic acid and 1,4-butanediol, while polybutylene succinate adipate can be prepared from 1,4-butanediol and a mixture of adipic acid and succinic acid. Polybutylene succinate polymers have been described, for example, in EP 0 569 153 A2.

[0041] Suitably, the polybutylene succinate based polyester to be used according to the present invention has a melt flow rate in the range of 10-50 g / 10 min, preferably in the range of 10-40 g / 10 min, more preferably in the range of 15-35 g / 10 min, determined according to ASTM D1238 (190° C., 2.16 kg).

[0042] The polybutylene succinate-based polyester to be used according to the present invention suitably has a melting point between 80-120°C, preferably between 85-115°C. The polybutylene succinate-based polyester suitably has a weight average molecular weight in the range of 30,000 to 120,000 Daltons, preferably in the range of 50,000 to 100,000 Daltons. The polymer blend composition for the second component suitably has a melt flow rate in the range of 2-100 g / 10 min, preferably in the range of 4-90 g / 10 min, more preferably in the range of 5-80 g / 10 min, even more preferably in the range of 5-50 g / 10 min, most preferably in the range of 5-40 g / 10 min, as determined according to ASTM D1238 (190°C, 2.16 kg).

[0043] The multicomponent spunbond fibers to be used according to the present invention suitably have a linear mass density in the range of 1-5 dtex. In other embodiments, for example, the multicomponent spunbond fibers suitably have a dtex number in the range of 1.5-3 dtex. In other embodiments, for example, the multicomponent spunbond fibers suitably have a linear mass density in the range of 1.6-2.5 dtex. According to the present invention, the first component of the multi-component spunbond fibers (preferably bicomponent spunbond fibers) is present in an amount ranging from 50-80% by weight, and the second component of the multi-component spunbond fibers is present in an amount ranging from 20-50% by weight, both weights being based on the total weight of each multi-component spunbond fiber. Preferably, the first component of the multi-component spunbond fibers is present in an amount ranging from 55-80% by weight, and the second component of the multi-component spunbond fibers is present in an amount ranging from 20-45% by weight, both weights being based on the total weight of each multi-component spunbond fiber. More preferably, the first component of the multi-component spunbond fibers is present in an amount ranging from 55-75% by weight, and the second component of the multi-component spunbond fibers is present in an amount ranging from 25-45% by weight, both weights being based on the total weight of each multi-component spunbond fiber. Even more preferably, the first component is present in an amount ranging from 60-75 weight percent and the second component is present in an amount ranging from 25-40 weight percent, both weights based on the total weight of each multicomponent spunbond fiber. Advantageously, it has been found according to the present invention that, compared with the nonwoven fabrics of the same or similar preparation that do not include polybutylene succinate-based polyester, adding a small amount of polybutylene succinate-based polyester in the second component (e.g., sheath component) can provide a significant increase in mechanical properties. In this regard, nonwoven fabrics according to the present invention suitably show a tensile strength greater than 50% of the nonwoven fabrics of similar preparation that do not include polybutylene succinate-based polyester. This nonwoven fabric can show a tensile strength greater than 50% to more than 500% of the tensile strength of the nonwoven fabrics of similar preparation that do not include polybutylene succinate-based polyester. The nonwoven fabric according to the present invention suitably exhibits an increase in machine direction (MD) tensile strength of about 50 to 500% or more compared to a similarly prepared nonwoven fabric that does not include the polybutylene succinate-based polyester. The nonwoven fabric preferably exhibits an increase in MD tensile strength in the range of 50 to 500% or more, more preferably in the range of 100 to 500% or more, even more preferably 200 to 500% or more, most preferably 250 to 500% or more compared to a similarly prepared nonwoven fabric that does not include the polybutylene succinate-based polyester.

[0044] The nonwoven fabric according to the present invention suitably exhibits an increase in cross-machine direction (CD) tensile strength of 50 to 800% or more compared to a similarly prepared nonwoven fabric that does not include the polybutylene succinate-based polyester. In some embodiments, the present nonwoven fabric preferably exhibits an increase in CD tensile strength ranging from 50 to 800% or more, more preferably 100 to 800% or more, even more preferably 200 to 800% or more, and most preferably 250 to 800% or more compared to a similarly prepared nonwoven fabric that does not include the polybutylene succinate-based polyester.

[0045] The nonwoven fabrics according to the present invention also exhibit increased toughness compared to similarly prepared nonwoven fabrics that do not include polybutylene succinate-based polyesters. The toughness of nonwoven fabrics can be compared by examining the product of the observed elongation percentage and the observed tensile strength of the fabric. This product is called the toughness index, which is approximately proportional to the area under the stress-strain curve. As discussed below in the test method section, all tensile and elongation values ​​are obtained according to German method 10 DIN 53857, where the peak values ​​of samples with a width of 5 cm and a gauge length of 100 mm are recorded at a crosshead speed of 200 mm / min. Because the toughness index is the product of tensile × elongation %, the units of the toughness index are (N / 5 cm)-%. Since all mechanical properties are obtained by testing 5 cm wide samples, the units of the toughness index in this document will be simplified to N-%.

[0046] The nonwoven fabric according to the present invention suitably exhibits an MD toughness index in the range of 80-2000 N-%, particularly in the range of 100-1800, more particularly in the range of 120-1500 N-%; and a CD toughness index in the range of 80-1500 N-%, particularly in the range of 100-1200, more particularly in the range of 120-1000 N-%.

[0047] The nonwoven fabric according to the present invention suitably exhibits an increase in the MD toughness index in the range of 200-5700% compared to a similarly prepared nonwoven fabric that does not include a polybutylene succinate-based polyester. In some embodiments, the nonwoven fabric suitably exhibits an increase in the CD toughness index in the range of 160-3200% compared to a similarly prepared nonwoven fabric that does not include a polybutylene succinate-based polymer. In order to illustrate the change in basis weight, it is also useful to consider the relative toughness index of the nonwoven fabric of the present invention compared to a similarly prepared nonwoven fabric that does not include a polybutylene succinate-based polymer. The nonwoven fabric also exhibits a significant increase in toughness compared to the nonwoven fabric of the comparative example. The relative toughness index is calculated from the toughness index and then normalized for basis weight. The toughness index can be divided by the basis weight to provide a normalized toughness index in units of N-% / g / m 2 .

[0048] The nonwoven fabric according to the present invention may exhibit a range of 2.5-55 N-% / g / m 2 , especially in the range of 5-55N-% / g / m 2 , more particularly in the range of 10-50 N-% / g / m 2 MD relative toughness index; and range of 1.5-35 N-% / g / m 2 , specifically in the range of 1.8-30 N-% / g / m 2 , more particularly in the range of 2-30 N-% / g / m 2 CD relative toughness index.

[0049] In some embodiments, the present nonwoven fabric can exhibit an increase in MD relative toughness index ranging from 100-3500% compared to a similarly prepared nonwoven fabric that does not include the polybutylene succinate-based polyester. The present nonwoven fabric can exhibit an increase in CD relative toughness index ranging from 100-2000% compared to a similarly prepared nonwoven fabric that does not include the polybutylene succinate-based polyester.

[0050] "Similarly prepared nonwovens" should be understood as comparative nonwovens having the same polymer composition except for the polybutylene succinate-based polyester and possibly slight differences in processing conditions such as temperature (e.g., extruder, calender and die temperature), stretching speed and pressure.

[0051] The presence of the polybutylene succinate-based polyester helps to improve the bonding of the multi-component spunbond fibers to each other, thereby improving the mechanical properties of the nonwoven fabric. The present nonwoven fabric suitably has a peak machine direction (MD) tensile strength per gram basis weight in the range of 0.5-2.5 (N / 5 cm) / gsm. For example, the present nonwoven fabric may include a peak MD tensile strength per gram basis weight of 0.7-2.2 (N / 5 cm) / gsm. In certain embodiments, for example, the present nonwoven fabric may have a peak CD tensile strength of 0.25-1.5 (N / 5 cm) / gsm. In other embodiments, for example, the nonwoven fabric may include a peak CD tensile strength of 0.3-1.1 (N / 5 cm) / gsm. In some embodiments, for example, the nonwoven fabric may include a peak CD tensile strength of 0.5-1.9 (N / 5 cm) / gsm. According to certain embodiments, for example, the nonwoven fabric may include a peak MD elongation percentage of 20-50%. In other embodiments, for example, the nonwoven fabric may include a peak MD elongation percentage of 25-45%. In other embodiments, for example, the nonwoven fabric may include a peak MD elongation percentage of 28-40%. In certain embodiments, for example, the nonwoven fabric may include a CD elongation percentage peak of 20-75%. In other embodiments, for example, the nonwoven fabric may include a CD elongation percentage peak of 25-60%. In some embodiments, for example, the nonwoven fabric may include a CD elongation percentage peak of 30-50%. In addition to the additives in the polylactic acid and polybutylene succinate-based polyesters already present in the spunbonded nonwoven fibers, the interpolation of other additives can also provide additional properties for the fiber. Suitable other additives include heat stabilizers, light stabilizers, slip additives, waxes and additives that make the fabric hydrophilic or hydrophobic. The interpolation of filler materials is also advantageous sometimes. Suitable filler materials include organic and inorganic filler materials. Suitable examples of inorganic filler materials include minerals such as calcium carbonate, metals such as aluminum and stainless steel. Suitable examples of organic filler materials include sugar-based polymers. The multicomponent spunbond fibers to be used according to the present invention may additionally include a slip agent. When the first and second components of the multicomponent spunbond fibers are prepared in the form of a masterbatch during the fabric manufacturing process, such as during the spinning process, the slip agent is suitably added to these components. The slip agent to be used according to the present invention may be any slip agent that can be suitably used for the manufacture of nonwoven fabrics. It may be an internal slip agent that is generally compatible with the polymer matrix, or it may be an external slip agent that migrates to the fiber surface due to a certain incompatibility with the polymer matrix. Suitably, the slip agent may be a hydrocarbon compound or a fatty acid derivative having one or more functional groups selected from alcohols, carboxylic acids, aryls and substituted aryls, alkoxylates, esters, amides. The slip agent may also be a fatty acid ester of a polyvalent alcohol, a compound comprising an unsaturated C—C bond, oxygen, nitrogen, or a compound based on a silicon-containing compound. Typical examples of particularly attractive slip agents are, for example, polyethylene and polypropylene waxes, primary and secondary amides (such as, for example, erucamide and oleamide) and stearyl derivatives.

[0052] The glidant is suitably present in an amount ranging from 0.1 to 5% by weight, preferably 0.5 to 3% by weight, based on the total weight of the first component. The glidant is suitably present in an amount ranging from 0.1 to 5% by weight, preferably 0.5 to 3% by weight, based on the total weight of the second component.

[0053] The slip agent is suitably present in an amount ranging from 0.1 to 5% by weight, preferably 0.5 to 3% by weight, based on the total weight of the multicomponent spunbond fibers.

[0054] Suitably, a side of nonwoven layer is provided with the pattern of bonding area, which limits the pattern of non-bonding area. Preferably, bonding area is personalized bonding area, which means that bonding area is arranged separately, rather than interconnected. Before or after nonwoven layer is provided with the pattern of personalized bonding area, nonwoven layer can be processed by air bonding.

[0055] Preferably, this side of the nonwoven is provided with only one type of bonding area pattern. Preferably, the bonding area is a personalized bonding area having a circular, diamond, rectangular, square, oval, triangle, heart, moon, star, rod, hexagon, octagon or another polygonal shape.

[0056] Preferably, at least one outer side of the spunbond nonwoven layer is provided with a pattern of personalized bonding areas, wherein the surface of the bonding areas is in the range of 8-25%, more preferably in the range of 8-15%, most preferably in the range of 10-12%, based on the total surface of the at least one outer side of the spunbond nonwoven layer.

[0057] The bonding area can have a circular, diamond, rectangular, square, oval, triangle, stick, heart, moon star, hexagon, octagon or another polygonal shape. For example, the pattern of the personalized bonding area can be various shapes, such as a diamond pattern, a hexagonal dot pattern, an oval-elliptical pattern, a stick pattern or any combination thereof. Suitably, the pattern of the personalized bonding area is a continuous pattern.

[0058] Suitably, the pattern of personalised bonded areas defines a pattern of non-bonded areas whereby the surface of the non-bonded areas is in the range of 75-92%, preferably in the range of 85-92%, more preferably in the range of 88-90%, based on the total surface of the at least one outer side of the spunbond nonwoven layer.

[0059] The high surface of the non-bonded area to be used according to the invention provides an attractive high softness. In addition, the larger non-bonded area allows the fibers to become fluffy and increase the fluffiness of the fabric. From a visual and tactile point of view, this will be perceived as an even higher softness. In a preferred embodiment of the present invention, the bonding area has a rhombus, rod, oval or circular shape. More preferably, the bonding area has a rhombus or rod shape. Most preferably, the bonding area has a rhombus shape. Suitably, the maximum width of the bonding area is in the range 0.7-1.5 mm, preferably in the range 0.75-1.25 mm, more preferably in the range 0.8-1.2 mm.

[0060] Suitably, the surface of the bonding area is between 0.38 and 1.77 mm 2 In the range of 0.44-1.22 mm 2 In the range of 0.50-1.13 mm 2 within the range. In the case of individualized bonding areas in the form of ovoids, they can be arranged in any direction of the web. Preferably, the bonding areas in the form of ovoids are arranged in such a way that adjacent ovoids arranged in the transverse direction each form an angle relative to the longitudinal direction of the web. The ovoids can be suitably arranged in such a way that in the longitudinal direction, a plurality of uninterrupted areas extend continuously along the web, while in the transverse direction, there are no uninterrupted areas along the web. In this preferred rod-shaped arrangement, the width of these uninterrupted areas in the transverse direction is suitably greater than 300 μm, and preferably, the width is in the range of 500-800 μm. In another preferred embodiment according to the invention, at least one of the spunbond nonwoven layers comprises a side provided with a pattern of alternating individualized bonding areas in the form of rods arranged in the transverse direction of the web. Preferably, the rods are arranged in such a way that in the longitudinal direction of the web there are no uninterrupted areas along the web, whereas in the transverse direction of the web the arrangement of the rods defines a plurality of uninterrupted areas extending continuously along the web.

[0061] In the context of the present invention, the term "rod-shaped" is intended to define a linear rectilinear shape, such as a straight rod or stick. The surface of the bonding areas in the form of rods is preferably in the range of 8-15%, more preferably in the range of 9-12% of the total surface area of ​​the at least one outer side of the spunbond nonwoven layer.

[0062] Preferably, the personalized bonding area in the form of a rod each forms an angle of 90 ° with the longitudinal direction of the web in its length direction. The pattern of the bonding area in the form of a rod can obtain many improved fabric properties. Since the fiber is bound boldly perpendicular to its preferred laying direction, the tensile strength in the transverse direction is significantly improved. Therefore, it is important that there is no uninterrupted area in the preferred laying direction (i.e., longitudinal direction) because this will produce a weak unbonded fiber area, resulting in a decrease in tensile strength. In addition, since there is no uninterrupted area along the web in the longitudinal direction, the free fiber length (i.e., the average length of a single fiber between its first bonding and the second bonding) is relatively short, resulting in improved wear resistance. In addition, this special rod-shaped arrangement provides an uninterrupted non-bonded area in the transverse direction, thereby significantly reducing the bending force of the fabric and converting into excellent drape without sacrificing mechanical strength. This discovery is surprising because these two properties are usually mutually exclusive. The rod shape may have a flat end and / or a curved end. Preferably, the curved end has a circular shape. Preferably, the rod shape has a linear shape. Suitably, the length of the personalized adhesive area in the form of a rod is 2-10 times, preferably 2-8 times, its width.

[0063] The depth of the discrete non-bonded areas between the bars is suitably in the range 0.1-0.8 mm, preferably in the range 0.1-0.6 mm, more preferably in the range 0.15-0.5 mm, most preferably in the range 0.15-0.4 mm.

[0064] Suitably, the distance between each pair of adjacent rods in the transverse direction is in the range of 1.8-3.0 mm, preferably 2.2-2.6 mm. Suitably, the distance between each pair of adjacent rods in the longitudinal direction is in the range of 2.5-5.0 mm, preferably 3.3-4.2 mm. When the personalized bonding area has a diamond shape, the distance between each pair of adjacent diamonds in the transverse direction is in the range of 0.15-3 mm, preferably 0.5-2.5 mm. Suitably, the distance between each pair of adjacent diamonds in the longitudinal direction is in the range of 0.15-3 mm, preferably 0.5-2.5 mm.

[0065] The multicomponent spunbond fibers to be used according to the present invention preferably have a circular fiber cross section. Other suitable fiber cross sections include, for example, ribbon-shaped or trilobal cross sections.

[0066] The present invention also relates to a method for preparing a nonwoven fabric according to the present invention, comprising the following steps: (a) providing a molten or semi-molten polylactic acid flow; (b) providing a blend stream of molten or semi-molten polylactic acid and molten or semi-molten polybutylene succinate-based polyester; (c) forming a plurality of multicomponent spunbond fibers from a molten or semi-molten polylactic acid stream and a molten or semi-molten polylactic acid and molten or semi-molten polybutylene succinate-based polyester blend stream, the multicomponent spunbond fibers comprising a first component and a second component, the first component comprising a single polymer composition comprising polylactic acid and the second component comprising a polymer blend composition comprising polylactic acid and polybutylene succinate-based polyester, wherein the first component is present in an amount ranging from 50 to 80 weight percent and the second component is present in an amount ranging from 20 to 50 weight percent based on the total weight of each multicomponent spunbond fiber, and wherein the amount of polybutylene succinate-based polyester is in the range of 0.2 to 5 weight percent based on the total weight of each multicomponent spunbond fiber; and (d) forming a nonwoven web from the multicomponent spunbond fibers obtained in step (c).

[0067] In step (d), a plurality of stretched multi-component spunbond fibers are suitably deposited onto a collecting surface. The plurality of multi-component spunbond fibers may be exposed to ions, for example, before they are bonded to form the present nonwoven fabric. According to certain embodiments, for example, forming a plurality of continuous multi-component fibers may include spinning with a plurality of continuous multi-component fibers, stretching a plurality of continuous multi-component fibers, and randomizing a plurality of continuous multi-component fibers.

[0068] In step (c), a fiber drawing speed of greater than 2500 m / min may be suitably applied. In other embodiments, for example, the fiber drawing may be carried out at a fiber drawing speed of 3000-4000 m / min. In other embodiments, for example, the process may be carried out at a fiber drawing speed of 3000-5000 m / min. The nonwoven web obtained in step (d) can be bonded to form this nonwoven fabric, and this bonding can include that the web is carried out thermal point bonding with heat and pressure via a calender having a pair of cooperative rollers including a patterned roller. In such embodiments, for example, the web is carried out thermal point bonding and can include that a three-dimensional geometric bonding pattern is imparted to this nonwoven fabric. The patterned roller can include a three-dimensional geometric bonding pattern. In the bonding pattern, the bonding area can be suitably an individualized bonding area with a circular, rhombus, rectangle, square, oval, triangle, heart-shaped, moon-star, rod-shaped, hexagonal, octagonal or another polygonal shape.

[0069] The calender may include a release coating to minimize deposition of molten or semi-molten polymer on the surface of one or more rollers. For example, such release coatings are described in European Patent Application No. 1,432,860, which is incorporated herein by reference in its entirety.

[0070] The method according to the present invention may also include dissipating static charge from the nonwoven fabric near the calender via an electrostatic control unit. In some embodiments, for example, the electrostatic control unit may include an ionization source. In other embodiments, for example, the ionization source may include an ionization rod. However, in other embodiments, for example, dissipating static charge from the nonwoven fabric may include contacting the nonwoven fabric with an electrostatic rod.

[0071] The method may also include cutting the nonwoven fabric to form a cut nonwoven fabric, exposing the cut nonwoven fabric to ions via a third ionization source, and winding the cut nonwoven fabric into a roll. In such embodiments, for example, the third ionization source may include an ionization rod.

[0072] The method can also include increasing humidity while forming a plurality of continuous multi-component spunbond fibers. In such embodiments, for example, increasing humidity can include applying at least one of steam, mist, water vapor, or any combination thereof to the plurality of continuous multi-component spunbond fibers.

[0073] The present nonwoven fabric can be produced, for example, by conventional spunbonding on a spunbond machine, such as, for example, the Reicofil-3 line or the Reicofil-4 line from Reifenhäuser, as described in U.S. Pat. No. 5,814,349 to Geus et al., wherein the molten fiber components are extruded into continuous multicomponent spunbond fibers, which are then quenched, pneumatically attenuated by a high-speed fluid, and collected on a collection surface in a randomly arranged manner. In some embodiments, the continuous fibers are collected by means of a vacuum source located below the collection surface. After the filaments are collected, any thermal, chemical or mechanical bonding treatment can be used to form a bonded web, thereby producing a bonded web structure. As will be understood by those skilled in the art, examples of thermal bonding can include through-air bonding, in which hot air is forced through the web to soften the polymer outside of some fibers in the web, followed by at least limited compression of the web; or calendering bonding, in which the web is compressed between two rollers, at least one of which is heated, and typically one of which is an embossed roller.

[0074] In some embodiments of the present method, the collecting surface may include conductive fibers. The conductive fibers may include monofilaments made of polyethersulfone conditioned with polyamide (e.g., Huycon-LX 135). In the longitudinal direction, the fibers include polyethersulfone conditioned with polyamide. In the transverse direction, the fibers include a combination of polyethersulfone conditioned with polyamide and additional polyethersulfone.

[0075] The present nonwoven fabrics can be used to prepare a variety of different structures. For example, in some embodiments, the present nonwoven fabrics can be combined with one or more additional layers to prepare a composite material or laminate. Examples of such composite materials / laminates can include spunbond composites, spunbond-meltblown (SM) composites, spunbond-meltblown-spunbond (SMS) composites, or spunbond-meltblown-meltblown-spunbond (SMMS) composites. In some embodiments, a composite material comprising a layer of the present nonwoven fabric and one or more film layers can be prepared.

[0076] The present invention also provides a nonwoven fabric, which includes at least two nonwoven spunbond layers and one or more meltblown nonwoven layers, the two nonwoven spunbond layers each include spunbond fibers, and the one or more meltblown nonwoven layers each include meltblown fibers, wherein the one or more meltblown nonwoven layers are arranged between the spunbond nonwoven layers, wherein the spunbond fibers of the spunbond nonwoven layers are multicomponent fibers including a first component and a second component, wherein the first component includes a single polymer composition, and the second component includes a polymer blend composition, wherein the single polymer composition includes polylactic acid, and the polymer blend composition includes polylactic acid and polybutylene succinate-based polyester, wherein the first component is present in an amount ranging from 50-80% (weight), and the second component is present in an amount ranging from 20-50% (weight), both amounts are based on the total weight of each multicomponent spunbond fiber, and wherein the amount of polybutylene succinate-based polyester is in the range of 0.2-5% (weight) based on the total weight of each multicomponent spunbond fiber.

[0077] In such multi-layer nonwoven embodiments, at least one of the meltblown layers further comprises polylactic acid.

[0078] The spunbond fibers and meltblown fibers are suitably bonded together by bonding to form a cohesive web structure. Suitable bonding techniques include, but are not limited to, chemical bonding and thermal bonding, such as thermal calendering or air-through bonding using a stream of hot air.

[0079] Spunbond fibers are generally continuous and have a fiber diameter in the range of 10-100 μm, preferably in the range of 10-50 μm, more preferably in the range of 10-35 μm, and most preferably in the range of 10-30 μm.

[0080] Meltblown fibers are generally continuous and have a fiber diameter in the range of 0.1-10 μm, preferably in the range of 0.5-8 μm, and more preferably in the range of 1-5 μm.

[0081] In these multilayer structures, the basis weight of the nonwoven layer can be as low as 5-150 g / m 2 In such a multi-layer laminate, both meltblown and spunbond fibers may have PLA on the surface to ensure optimal bonding. In some embodiments where the spunbond layer is part of a multi-layer structure (e.g., SM, SMS, and SMMS), the amount of meltblown in the structure as a percentage may be in the range of about 5 to 30% of the structure, particularly about 5 to 15%.

[0082] The multilayer structure according to the embodiment can be prepared in a variety of ways, including a continuous in-line process, wherein each layer is prepared in a continuous sequence on the same production line, or a meltblown layer is deposited on a previously formed spunbond layer. The layers of the multilayer structure can be bonded together using thermal bonding, mechanical bonding, adhesive bonding, hydroentanglement, or a combination of these methods to form a multilayer composite sheet material. In certain embodiments, the layers are thermally bonded to each other by passing the multilayer structure through a pair of calender rolls.

[0083] The present invention also provides an absorbent article. The absorbent article includes a nonwoven fabric according to the present invention. In one embodiment, a sustainable composite material including at least two nonwoven fabric layers can be provided, so that at least one nonwoven fabric layer includes a layer of the present nonwoven fabric. The present nonwoven fabric layer includes a plurality of multi-component spunbond fibers, wherein the polybutylene succinate-based polyester and PLA are present at the surface of the plurality of multi-component spunbond fibers. The nonwoven fabric can be used in a variety of products and applications. For example, embodiments of the present invention can be used in personal care applications, such as baby care products (diapers, wet wipes), feminine care products (pads, sanitary napkins, tampons), adult care products (incontinence products), or cosmetic application products (cosmetic cotton pads). Other possible uses include agricultural applications (e.g., root wraps, seed bags, crop covers), industrial applications (e.g., work clothes, airline pillows, car trunk liners, sound insulation), and household products (e.g., mattress spring covers and furniture scratch pads).

[0084] When the absorbent is a diaper comprising an absorbent core sandwiched between a face cloth and a back cloth, one or both of the face cloth and the back cloth may comprise the present nonwoven fabric and / or a sustainable composite material comprising a layer of the present nonwoven fabric. The face cloth will be positioned adjacent to the outer surface of the absorbent core and is preferably connected to the absorbent core and the back cloth by connection means such as are known in the art. For example, the face cloth may be fixed to the absorbent core by a uniform continuous adhesive layer, a patterned adhesive layer, or an array of separate adhesive lines, spirals, or dots.

[0085] Therefore, the present nonwoven fabric can be suitably used for the face and back fabric of diapers. In addition, in view of its high wet strength, the present nonwoven fabric can be advantageously used for wet wipes. In addition, the nonwoven fabrics exhibit high elongation, which makes them useful for various diaper parts, such as waist supports, back ears and side panels.

[0086] Example The following examples are provided to illustrate one or more embodiments of the present invention and should not be construed as limiting the invention.

[0087] Test Method Titer is calculated according to German Textile Method C-1570 from microscopic measurements of fiber diameter and known polymer density.

[0088] Basis weight is usually determined according to German weaving method CM-130 from the weight of 10 layers of fabric cut into 10 x 10 cm squares.

[0089] Tensile strength was determined using specimens of 5 cm width, 100 mm gauge length and a crosshead speed of 200 mm / min according to method 10 DIN 53857. The peak tensile strength was measured.

[0090] The elongation is determined according to method 10 DIN 53857 using specimens of 5 cm width, 100 mm gauge length and a crosshead speed of 200 mm / min. The peak elongation is measured.

[0091] Both tensile strength and elongation are determined under dry and wet conditions. In the wet condition, the nonwoven is moistened with water.

[0092] Comparative Example 1 In Comparative Example 1, a 100% PLA bicomponent fabric was prepared on a Reicofil-4 beam. A press roll (R-4 press roll) was located on the collecting surface, downstream of where the fibers were deposited on the collecting surface. The fibers were bicomponent 30 / 70 PLA ​​NatureWorks Grade 6202 / PLA NatureWorks Grade 6202 / sheath / core. PLA NatureWorks Grade 6202 had a melt flow rate of 15-30 g / 10 min (determined according to ASTM D1238 (190°C, 2.16 kg)) and a melting point of 155-170°C.

[0093] The nonwoven fabric of Comparative Example 1 was produced at a spin beam temperature of 235°C at the extruder and at a spin beam temperature of 235°C at the die. The nonwoven fabric of Comparative Example 1 was produced at a production volume of 270 kg / h and a chamber pressure of 4800 Pa. The calendering temperature of the pattern roll of the calender of Comparative Example 1 was 125°C, the calendering temperature of the anvil roll was 125°C, and the calendering pressure was 40 N / mm. The bonding area had a rhombus shape, the fineness of the fiber was 2.65 dtex, and the basis weight of the nonwoven fabric was 28.5 gsm.

[0094] Embodiment 1 of the present invention In Inventive Example 1, a nonwoven fabric was made from bicomponent fibers having a 30 / 70 sheath / core structure. The masterbatch from which the sheath was made included a PLA resin (Naturworks grade 6202) to which 3% by weight of polybutylene succinate (BioPBS FZ78TM / PTT MCC BioChem) was added. The melt flow rate of BioPBS FZ78TM / PTT MCC BioChem was 22 g / 10 min (determined according to ASTM D1238 (190°C, 2.16 kg)) and the melting point was 115°C. The system was set up the same as described above for Comparative Example 1. The nonwoven fabric of Inventive Example 1 was produced at a spinning warp temperature of 235°C at the extruder and a spinning warp temperature of 235°C at the die. The nonwoven fabric of Inventive Example 1 was produced at a throughput of 270 kg / h and a chamber pressure of 4500 Pa. The calendering temperature of the pattern roll of the calender of Inventive Example 1 was 161° C., the calendering temperature of the anvil roll was 161° C., and the calendering pressure was 40 N / mm. The bonding area had the same rhombus shape as in Comparative Example 1, the fineness of the fiber was 2.96 dtex, and the basis weight of the nonwoven fabric was 29.2 gsm. The properties of Inventive Example 1 and Comparative Example 1 are summarized in Tables 1 and 2 below.

[0095] Table 1

[0096] Table 2

[0097] As can be seen from Tables 1 and 2, the nonwoven fabric according to the present invention exhibits significant improvements in mechanical properties compared to Comparative Example 1 using an identically prepared PLA nonwoven fabric that does not include polybutylene succinate. Based on this data, it can be seen that the nonwoven fabric of the present invention exhibits an increase in tensile strength of greater than 50% compared to Comparative Example 1. Table 1 shows that the nonwoven fabric according to the present invention exhibits significant increases in MD tensile strength and CD tensile strength. Furthermore, Table 2 shows that the nonwoven fabric according to the present invention exhibits a significant increase in MD elongation and CD elongation.

[0098] Furthermore, the wet tensile strength obtained with the nonwoven fabric of Example 1 of the present invention indicates that the nonwoven fabric according to the present invention can be advantageously used in wet wipes applications.

[0099] It is clear from Tables 1 and 2 that a significant increase in tensile strength and elongation is obtained when a small amount of PBS (3 wt %) is used in the sheath component, compared to a sheath component made from PLA alone.

[0100] In order to further evaluate the basis for the increase in tensile strength, elongation and toughness of the nonwoven fabric of the present invention, SEM images of the fabric surface of Comparative Example 1 and Example 1 of the present invention were obtained. Figures 1 and 2 are SEM images of Comparative Example 1 and Example of the present invention, respectively, obtained at a magnification of 200 times. These images were obtained using a Keyence VHX digital microscope.

[0101] Significant differences in the bonding between the fibers were observed. In particular, the bond points of the fabric of Comparative Example 1 indicated that the individual fibers were loosely bonded together and that there was minimal polymer flow bonding adjacent fibers to each other. In contrast, the bond points of the fabric of Inventive Example 1 indicated significant melting and flow of the polymer of the individual fibers. Thus, the present nonwoven fabric exhibited a significant improvement in bonding compared to the comparative nonwoven fabric that did not include a small amount of polybutylene succinate.

[0102] As can be clearly seen from the above, the nonwoven fabric according to the present invention including only a small amount of PBS exhibits significant improvements in MD and CD tensile strength, MD and CD elongation, and bonding ability compared to Comparative Example 1 including a PLA resin but not PBS in the sheath component.

Claims

1. A nonwoven fabric comprising a plurality of multicomponent spunbond fibers, the plurality of multicomponent spunbond fibers being continuous fibers bonded together to form a nonwoven web, the multicomponent spunbond fibers having a core-sheath structure, wherein the core portion comprises a first component comprising a single polymer composition, and the sheath portion comprises a second component comprising a polymer blend composition, wherein the single polymer composition comprises polylactic acid, and the polymer blend composition comprises polylactic acid and polybutylene succinate-based polyester, wherein the first component is present in an amount ranging from 50 to 80 weight percent, and the second component is present in an amount ranging from 20 to 50 weight percent, both amounts being based on the total weight of each multicomponent spunbond fiber, and wherein the amount of polybutylene succinate-based polyester is in the range of 0.2 to 5 weight percent based on the total weight of each multicomponent spunbond fiber.

2. The nonwoven fabric of claim 1, wherein the first component is present in an amount ranging from 55-80 wt. % and the second component is present in an amount ranging from 20-45 wt. %, based on the total weight of each multicomponent spunbond fiber.

3. The nonwoven fabric according to claim 1 or 2, wherein the amount of the polybutylene succinate-based polyester is in the range of 0.2-2.5 wt% based on the total weight of each multi-component spunbond fiber.

4. The nonwoven fabric according to any one of claims 1 to 3, wherein the amount of the polybutylene succinate-based polyester is in the range of 0.2-2.0 wt% based on the total weight of each multi-component spunbond fiber.

5. The nonwoven fabric according to any one of claims 1 to 4, wherein the amount of the polybutylene succinate-based polyester is in the range of 0.2-1.5 wt% based on the total weight of each multicomponent spunbond fiber. 6 . The nonwoven fabric according to claim 1 , wherein the polybutylene succinate-based polyester is polybutylene succinate.

7. The nonwoven fabric according to any one of claims 1 to 6, wherein the single polymer composition comprises polylactic acid having a melt flow rate determined according to ASTM D1238 (210°C, 2.16 kg) in the range of 15-45 g / 10 min, and the polymer blend composition comprises polylactic acid having a melt flow rate determined according to ASTM D1238 (210°C, 2.16 kg) in the range of 15-45 g / 10 min and polybutylene succinate-based polyester having a melt flow rate determined according to ASTM D1238 (190°C, 2.16 kg) in the range of 15-35 g / 10 min.

8. The nonwoven fabric according to any one of claims 1 to 7, having a thickness of less than 50 g / m 2 The basis weight.

9. A nonwoven fabric according to any one of claims 1 to 8, wherein one side of the spunbond nonwoven layer is provided with a pattern of bonded areas.

10. The nonwoven fabric according to claim 9, wherein the bonding area is a personalized bonding area having a circular, diamond, rectangular, square, oval, triangle, heart, moon and star, rod, hexagon, octagon or another polygonal shape.

11. A method for preparing the nonwoven fabric according to claim 1, comprising the following steps: (a) providing a molten or semi-molten polylactic acid flow; (b) providing a blend stream of molten or semi-molten polylactic acid and molten or semi-molten polybutylene succinate-based polyester; (c) forming a plurality of multicomponent spunbond fibers from the molten or semi-molten polylactic acid stream and the molten or semi-molten polylactic acid and molten or semi-molten polybutylene succinate-based polyester blend stream, the multicomponent spunbond fibers being continuous fibers, the multicomponent spunbond fibers having a core-sheath structure, wherein the core portion comprises a first component, the first component comprising a single polymer composition comprising polylactic acid, and the sheath portion comprises a second component, the second component comprising a polymer blend composition comprising polylactic acid and polybutylene succinate-based polyester, wherein the first component is present in an amount ranging from 50 to 80 wt % based on the total weight of each multicomponent spunbond fiber, and the second component is present in an amount ranging from 20 to 50 wt %, and wherein the amount of polybutylene succinate-based polyester is in the range of 0.2 to 5 wt % based on the total weight of each multicomponent spunbond fiber; and (d) forming the spunbond nonwoven web from the multi-component spunbond fibers obtained in step (c).

12. An absorbent article comprising the nonwoven fabric according to any one of claims 1 to 10.

13. The absorbent article according to claim 12, wherein the absorbent article is selected from the group consisting of: hygiene articles, incontinence articles, diapers, sanitary pads, wet wipes and feminine care articles.

14. The absorbent article according to claim 13, which is a wet wipe.

Images