CN119563056A

CN119563056A - Nonwoven fabric and method of forming the same

Info

Publication number: CN119563056A
Application number: CN202380055582.0A
Authority: CN
Inventors: 埃琳娜·诺瓦里诺; 阿尔弗雷德·伊佐
Original assignee: Fitesa Germany GmbH
Current assignee: Fitesa Germany GmbH
Priority date: 2022-08-05
Filing date: 2023-08-03
Publication date: 2025-03-04
Also published as: MX2025000544A; WO2024028420A1; EP4565737A1; PE20250964A1

Abstract

The present invention provides a nonwoven fabric comprising a spunbond nonwoven layer comprising spunbond fibers, wherein the spunbond fibers are bicomponent 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-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 bicomponent spunbond fiber, and wherein the amount of polybutylene succinate-based polyester is in the range of 0.2 to 5% by weight, based on the total weight of each multicomponent spunbond fiber. In addition, the invention also provides a method for preparing the non-woven fabric and an absorbent article comprising the non-woven fabric.

Description

Nonwoven fabric and method for forming the same

Technical Field

The present invention relates to a nonwoven fabric, a method for preparing the same, and an absorbent article comprising the same.

Background

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

Traditionally, such nonwoven fabrics have been made from thermoplastic polymers such as polyesters, polystyrene, polyethylene, and polypropylene. These polymers are generally very stable and can remain in the environment for a long period of time. However, there has recently been a trend to develop articles and products that are considered environmentally friendly and sustainable. As part of this trend, it has been desired to produce eco-friendly products that include increased sustainable levels to reduce the level of petroleum-based materials. Thus, there is a need for nonwoven fabrics made from sustainable and degradable polymers that are preferably derivable from renewable resources.

Polylactic acid or polylactide-based Polymers (PLA) provide a cost-effective way for sustainable content spunbond nonwovens that can be easily converted into consumer products. Polylactic acid (PLA) is produced from plant renewable raw materials, such as sugars or cellulose from food crops such as corn, sugar beet, sugar cane and wheat. Polylactic acid has the advantage of being compostable and will dissolve into carbon dioxide, biomass and water. In addition, polylactic acid is recyclable. Polylactic acid is mainly formed from the monomers lactic acid and cyclic diester lactide. Polylactic acid is generally 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.

To fully gain the cost-benefit advantage of PLA-based consumer products, PLA must be converted to a nonwoven fabric and then to the final consumer product at a very high rate while minimizing waste. However, due to the propensity of static electricity generation and accumulation on fibers having PLA polymers on the surface, it is difficult to combine the spinning, reticulating and bonding steps at the very high speeds required for economically attractive production of spunbond PLA with optimal fabric properties. In addition, when 100% PLA fibers are used, lower bonding temperatures are required to prevent the fibers from sticking to the calender rolls. Lower bonding temperatures can result in poor fabric properties such as lower tensile strength and poor elongation, thus underutilizing the potential of the polymer. In addition, 100% PLA fibers are electrostatically charged during spinning and processing, which also results in the fibers sticking to the calender rolls.

To overcome these drawbacks, nonwovens have been developed with fibers having a sheath/core bicomponent structure in which PLA is present in the core and a synthetic polymer such as polypropylene is 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 high-speed commercial production of nonwoven webs comprising PLA. Although commercial production of nonwoven fabrics comprising PLA and synthetic polymers in the sheath is possible, this solution cannot be extended far enough because the industry (and its consumers) is seeking full sustainability, so the nonwoven fabric is preferably 100% PLA. Further, JP2008208483a discloses a carded nonwoven web made from shorter staple fibers having a core/sheath configuration, wherein the core component comprises a first copolymer of L-lactic acid and D-lactic acid, and the sheath component comprises a second copolymer of polyalkylene succinate and L-lactic acid, in which second copolymer the L-lactic acid is present only in small amounts. While such carded nonwovens may be attractive from a biodegradability standpoint, they are bulky and soft and exhibit poor mechanical properties in terms of tensile strength and elongation. In addition, their basis weights are relatively high and therefore unattractive.

As an alternative to the two-component process, it is also suggested to use additives such as fatty acid salts in order to overcome these processing problems. While this approach presents advantages in improving the processing and final fabric properties, it also has a number of associated disadvantages. It requires additional processing steps to provide the aliphatic sulfonic acid, which is an environmentally unfriendly compound derived from petrochemistry, is neither sustainable nor biodegradable, and the use of aliphatic sulfonic acid increases the overall processing cost.

Merely replacing PLA with other biopolymers such as polybutylene succinate (PBS) is not a viable alternative, as they do not reach the necessary commercial quantities, which can lead to higher prices and make the final fabric too expensive, and their spinning and processing properties are very poor.

Accordingly, there remains a need for a fabric comprising PLA that exhibits improved mechanical properties in terms of tensile strength and elongation, and that is useful in absorbent articles such as diapers and wet wipes, and that addresses the drawbacks associated with the alternative methods described above.

Disclosure of Invention

Surprisingly, according to the present invention, it has been found 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.

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 in the range of 50-80 weight percent and the second component is present in an amount in the range of 20-50 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 0.2-5 weight percent, based on the total weight of each multicomponent spunbond fiber.

The nonwoven fabric has the advantage of exhibiting a significant improvement in tensile strength and elongation in both the machine direction and the transverse direction, as compared to the same nonwoven fabric that does not include a small amount of polybutylene succinate-based polyester. For example, the present nonwoven fabric may exhibit at least a 50% increase in tensile strength in both the machine and cross directions as compared to the same nonwoven fabric that does not include a small amount of polybutylene succinate-based polyester.

The increase in tensile strength allows the use of nonwoven fabrics with low basis weights, which is beneficial for instance for face and back cloths. Furthermore, a more open bonding pattern can be used without losing mechanical properties and improving comfort properties such as softness and drape.

The present nonwoven fabrics particularly exhibit high wet strength, making them most suitable for use in wet wipes.

In addition, the increase in elongation allows the nonwoven to be used in applications where elongation is important, such as lumbar support (WAIST CARRIER), back ear (back ear), and side panels (SIDE PANEL). It also allows post mechanical treatments such as ring rolling, embossing and perforating.

The present invention provides nonwoven fabrics, sustainable composites comprising the same, and sustainable articles comprising the same and/or the same.

The present invention is applicable to a spunbond nonwoven comprising a plurality of multicomponent fibers bonded to one another to form a bonded web, wherein a polymer blend composition is present at the surface of the plurality of fibers.

The polybutylene succinate-based polymer is present in the multicomponent spunbond fibers in small amounts, i.e., 0.2 to 5 weight percent, 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 in the range of from 0.2 to 3.5 weight percent, more preferably in the range of from 0.2 to 2.5 weight percent, even more preferably in the range of from 0.2 to 2.0 weight percent, and most preferably in the range of from 0.2 to 1.5 weight percent, based on the total weight of each multicomponent spunbond fiber.

The polybutylene succinate-based polyester is suitably present in an amount in the range of from 1 to 10 weight percent, preferably in an amount in the range of from 1 to 7 weight percent, more preferably in an amount in the range of from 1 to 5 weight percent, even more preferably in an amount in the range of from 1 to 4 weight percent, most preferably in an amount in the range of from 1 to 3 weight percent, based on the total weight of the second component.

The polylactic acid is suitably present in an amount in the range of from 90 to 99% by weight, preferably in an amount in the range of from 93 to 99% by weight, more preferably in an amount in the range of from 95 to 99% by weight, even more preferably in an amount in the range of from 96 to 99% by weight, most preferably in an amount in the range of from 97 to 99% by weight, based on the total weight of the second component.

Preferably, the plurality of multicomponent spunbond fibers comprises bicomponent spunbond fibers. The bicomponent spunbond fibers can have a core/sheath configuration or a side-by-side configuration. Preferably, the bicomponent spunbond fibers have a core/sheath configuration. In the case of bicomponent spunbond fibers having a core/sheath configuration, the first component corresponds to the core component comprising a single polymer composition and the second component corresponds to the sheath component comprising a polymer blend composition. The core-sheath bicomponent spunbond fibers can 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, the same grade of PLA is used in the first component and the second component.

The nonwoven fabric and sustainable composite materials comprising the same according to the present invention may be used in a variety of applications including diapers, feminine care products, wiping products, and incontinence products. Preferably, the present nonwoven is used in diaper and wiping article products, more preferably in wiping article products.

For the purposes of the present application, the following terms shall have the following meanings:

the term "fiber" may refer to a fiber of finite length or a filament of infinite length.

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. Further, this does not exclude additives added for color, antistatic properties, lubrication, hydrophilicity, liquid repellency, and the like.

As used herein, the term "polymer blend composition" refers to a polymer composition formed from a blend comprising two or more different types of polymers (in this case at least PLA and polybutylene succinate-based polymers). Of course, this does not exclude polymer blend compositions to which additives are added for color, antistatic properties, lubrication, hydrophilicity, liquid repellency, and the like. In addition, the polymer blend may additionally include other polymers such as Polyhydroxyalkanoate (PHA), poly-3-hydroxybutyrate copolymer (P3 HB), poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), and the like.

As used herein, the term "multicomponent" refers to fibers that include two components (e.g., bicomponent fibers), wherein the two components are extruded from different extruders. The single polymer composition and the polymer blend composition are preferably arranged in substantially constantly positioned distinct zones across the cross-section of the fibers. The components may be arranged in any desired configuration, such as sheath-core configuration, side-by-side configuration, pie-shaped configuration, islands-in-the-sea configuration, and the like. 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 may 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. No. 4,789,592,336,552 to Taniguchi et al, U.S. Pat. No. 5,108,820 to Kaneko et al, U.S. Pat. No. 4,795,668 to Kruege et al, U.S. Pat. No. 5,382,400 to Pike et al, U.S. Pat. No. 5,336,552 to Strack et al, and U.S. Pat. No. 6,200,669 to Marmon et al.

As used herein, the terms "nonwoven", "nonwoven web" and "nonwoven fabric" refer to a structure or web of material which is formed without the use of weaving or knitting processes and which is constructed from individual fibers or threads which are interlaid, but not in an identifiable, repeating manner. In the past, nonwoven webs have been formed by a variety of conventional processes such as, for example, meltblowing processes, spunbonding processes, and staple fiber carding processes.

As used herein, the term "meltblown" 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 to microfiber diameter. Thereafter, the meltblown fibers are carried by the gas stream and are deposited on a collecting surface to form a web of random meltblown fibers. Such a process is disclosed, for example, in U.S. Pat. No. 3,849,241 to Buntin et al.

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

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

As used herein, the term "spunbond" refers to a process that involves extruding 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 as compared to shorter staple fibers. Thus, spunbond fibers are much longer than staple fibers. The fibers are deposited on the collection surface to form a random arrangement of substantially continuous webs that can then be bonded together to form a bonded nonwoven. The production of spunbond nonwoven webs is shown in various patents such as, for example, U.S. Pat. nos. 3,338,992, 3,692,613, 3,802,817, 4,405,297 and 5,665,300.

Typically, these spunbond processes involve extruding fibers from a spinneret, quenching the fibers with an air flow to accelerate the solidification of the molten fibers, attenuating the fibers by applying a stretching tension (by pneumatically entraining the fibers in an air stream, or mechanically by winding the fibers onto a mechanical stretching roll), depositing the stretched fibers onto a collecting surface to form a web, and bonding the loose web to a nonwoven. Bonding may be any thermal or chemical bonding process, such as through air bonding or thermal point bonding.

As used herein, the term "thermal point bonding" refers to passing a material to be bonded, such as one or more webs, between a heated calender roll and an anvil roll. Calender rolls are typically patterned so that the fabric is bonded at discrete point bond sites, rather than across its entire surface.

As used herein, the term "through air bonding" refers to a process in which hot air is used to fuse fibers at the surface of the nonwoven web and optionally inside the nonwoven web. The hot air can either be blown through the wire in the oven or be drawn through the wire as it passes through the porous drum by creating a vacuum. The temperature of the heated air may be high enough to melt and/or fuse the second component (e.g., sheath component) of the multicomponent fiber (e.g., bicomponent fiber) without melting the first component (e.g., core component) of the multicomponent fiber. The heated air can also induce crimping of the multicomponent fibers (e.g., bicomponent fibers).

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. Furthermore, unless otherwise specifically limited, the term "polymer" shall include all possible geometric configurations of the material, including isotactic, syndiotactic and random symmetries.

As used herein, the term "composite" may be a structure comprising two or more layers, such as a film layer and a fibrous layer or multiple fibrous layers molded together. According to certain embodiments of the present invention, the two layers of the composite structure may be bonded together such that a majority of their common X-Y planar interfaces are bonded together.

The present nonwoven fabric comprises multicomponent spunbond fibers comprising a first component and a second component, wherein both components comprise polylactic acid and the second component additionally comprises a minor amount of polybutylene succinate-based polyester. These nonwoven fabrics exhibit improvements in tensile strength and elongation.

A variety of different PLA resins can be used in accordance with the present invention.

PLA resins should have the appropriate molecular properties to spin in a spunbond process. Suitable examples of the inclusion of PLA resins are supplied by Nature works LLC, such as grades 6752D, 6100D, and 6202D, of Minnetonka 55345, minnesota, which are believed to be produced in accordance with the teachings of U.S. Pat. Nos. 5,525,706 and 6,807,973 to Gruber et al. Other examples of suitable PLA resins may include L130, L175, LX530, and LX175, all from Corbion in the netherlands Huo Linhe m (Gorinchem) Arkelsedijk, 4206A C.

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

Both the first component and the second component of the multicomponent fiber according to the present invention may include one or more additional additives. For example, in such embodiments, the additive may include at least a colorant, a softening agent, a slip agent, an antistatic agent, a lubricant, a hydrophilic agent, a liquid repellent agent, an antioxidant, and the like, or any combination thereof.

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

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 was determined using ASTM test method D1238 (210 ℃,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.

According to the present invention, both the first component and the second component of the multicomponent spunbond fibers can comprise a mixture of different polylactic acids.

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 both components is the same.

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.

PLA to be used according to the invention may have a melting point in the range 125-180 ℃. For example, the PLA in the sheath component may have a melting point in the range of 125-135℃and the PLA in the core component may have a melting point in the range of 155-180 ℃.

Furthermore, different PLAs may have different weight percentages of the D isomer. For example, the PLA in the sheath component may have a weight percent of D-isomer up to and including 10% by weight, and the PLA in the core component may have a weight percent of D-isomer in the range of 90-100% by weight.

For example, the core component may comprise a PLA having a lower percentage of D-isomer of polylactic acid than the PLA polymer used in the sheath component. PLA polymers with a lower D isomer percentage will exhibit a higher degree of stress-induced crystallization during spinning, while PLA polymers with a higher D isomer percentage will remain in a more amorphous state during spinning. The more amorphous sheath component will promote bonding, while the core exhibiting a higher degree of crystallinity will provide strength to the fibers and thus to the final bonded web. In one particular embodiment, nature Works PLA grade PLA 6752 with 4% D isomer can be used as the sheath, while Nature Works grade 6202 with 2% D isomer can be used as the core component.

The present nonwoven may suitably have a basis weight in the range of 5 to 150 grams per square meter (gsm). In some embodiments, the present nonwoven may have a basis weight in the range of 8-100 gsm. Preferably, the present nonwoven has a basis weight of less than 50 gsm. Preferably, the basis weight of the nonwoven is in the range of 10-50 gsm, more preferably in the range of 10-30 gsm, most preferably in the range of 10-25 gsm.

The present nonwoven suitably has an area shrinkage of less than 5%, preferably less than 2%.

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

Suitably, the polybutylene succinate-based polyester to be used according to the 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, as determined according to ASTM D1238 (190 ℃,2.16 kg).

The polybutylene succinate-based polyesters to be used according to the invention suitably have a melting point of between 80 and 120 ℃, preferably between 85 and 115 ℃.

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 from 2 to 100 g/10 min, preferably in the range of from 4 to 90 g/10 min, more preferably in the range of from 5 to 80 g/10 min, even more preferably in the range of from 5 to 50 g/10 min, most preferably in the range of from 5 to 40 g/10 min, as determined according to ASTM D1238 (190 ℃,2.16 kg).

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 dtex numbers in the range of 1.5 to 3 dtex. In further embodiments, for example, the multicomponent spunbond fibers suitably have a linear mass density in the range of 1.6 to 2.5 dtex.

According to the present invention, the first component of the multicomponent spunbond fibers (preferably bicomponent spunbond fibers) is present in an amount in the range of 50-80% by weight and the second component of the multicomponent spunbond fibers is present in an amount in the range of 20-50% by weight, both weights being based on the total weight of each multicomponent spunbond fiber. Preferably, the first component of the multicomponent spunbond fibers is present in an amount in the range of 55 to 80 weight percent and the second component of the multicomponent spunbond fibers is present in an amount in the range of 20 to 45 weight percent, both weights being based on the total weight of each multicomponent spunbond fiber. More preferably, the first component of the multicomponent spunbond fibers is present in an amount in the range of 55 to 75 weight percent and the second component of the multicomponent spunbond fibers is present in an amount in the range of 25 to 45 weight percent, both weights being based on the total weight of each multicomponent spunbond fiber. Even more preferably, the first component is present in an amount in the range of 60 to 75 weight percent and the second component is present in an amount in the range of 25 to 40 weight percent, both weights based on the total weight of each multicomponent spunbond fiber.

Advantageously, it has been found in accordance with the present invention that the addition of a small amount of polybutylene succinate-based polyester to the second component (e.g., sheath component) provides a significant increase in mechanical properties as compared to an identically or similarly prepared nonwoven fabric that does not include polybutylene succinate-based polyester. In this regard, the nonwoven fabric according to the present invention suitably exhibits a tensile strength that is 50% greater than a similarly prepared nonwoven fabric that does not include a polybutylene succinate-based polyester. The present nonwoven fabric may exhibit a tensile strength that is 50% to 500% greater than that of a similarly prepared nonwoven fabric that does not include a 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 a polybutylene succinate-based polyester. The present 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, and most preferably 250 to 500% or more, as compared to a similarly prepared nonwoven fabric that does not include a polybutylene succinate-based polyester.

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, as compared to a similarly prepared nonwoven fabric that does not include a polybutylene succinate-based polyester. In some embodiments, the present nonwoven fabric preferably exhibits an increase in CD tensile strength in the range of 50 to 800% or more, more preferably 100 to 800% or more, even more preferably 200 to 800% or more, most preferably 250 to 800% or more, as compared to a similarly prepared nonwoven fabric that does not include a polybutylene succinate-based polyester.

The nonwoven fabric according to the invention also exhibits increased toughness compared to a similarly prepared nonwoven fabric that does not include a polybutylene succinate-based polyester. The toughness of nonwoven fabrics can be compared by examining the product of the percent observed elongation 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 methods section, all tensile and elongation values were obtained according to german method 10 DIN 53857, wherein peaks of samples having a width of 5 cm and a gauge length of 100 mm were recorded at a crosshead speed of 200 mm/min. Since the toughness index is the product of tensile x% elongation, the unit of toughness index is (N/5 cm) -%. Since all mechanical properties were obtained by testing 5 cm wide samples, the units of toughness index in this document will be reduced to N-%.

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

The nonwoven fabric according to the invention suitably exhibits an increase in MD toughness index in the range of 200-5700% compared to a similarly prepared nonwoven fabric that does not include polybutylene succinate-based polyesters. In some embodiments, the present nonwoven suitably exhibits an increase in CD toughness index in the range of 160-3200% as compared to a similarly prepared nonwoven that does not include a polybutylene succinate-based polymer. To illustrate the change in basis weight, it is also useful to consider the relative toughness index of the nonwoven fabrics of the present invention as compared to similarly prepared nonwoven fabrics that do not include polybutylene succinate-based polymers. The present nonwoven fabric also exhibited a significant increase in toughness as 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 may be divided by the basis weight to provide a normalized toughness index in units of N-%/g/m ².

The nonwoven fabric according to the invention may exhibit an MD relative toughness index in the range of 2.5-55N-%/g/m ², in particular in the range of 5-55N-%/g/m ², more in particular in the range of 10-50N-%/g/m ², and a CD relative toughness index in the range of 1.5-35N-%/g/m ², in particular in the range of 1.8-30N-%/g/m ², more in particular in the range of 2-30N-%/g/m ².

In some embodiments, the nonwoven fabric of the invention may exhibit an increase in MD relative toughness index in the range of 100-3500% as compared to similarly prepared nonwoven fabrics that do not include polybutylene succinate-based polyesters. The present nonwoven fabric may exhibit an increase in CD relative toughness index ranging from 100 to 2000% as compared to a similarly prepared nonwoven fabric that does not include a polybutylene succinate-based polyester.

"Similarly prepared nonwoven" is to be understood as a comparative nonwoven having the same polymeric composition except for the polybutylene succinate-based polyester and there may be minor differences in processing conditions such as temperature (e.g., extruder, calender and die temperatures), drawing speed and pressure.

The presence of the polybutylene succinate-based polyester helps to improve the adhesion of the multicomponent spunbond fibers to each other and thus improve the mechanical properties of the nonwoven.

The present nonwoven 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 may include an MD tensile strength peak per gram basis weight of 0.7-2.2 (N/5 cm)/gsm.

In certain embodiments, for example, the present nonwoven may have a cross-machine direction (CD) tensile strength peak of 0.25 to 1.5 (N/5 cm)/gsm. In other embodiments, for example, the nonwoven may include a CD tensile strength peak of 0.3 to 1.1 (N/5 cm)/gsm. In some embodiments, for example, the nonwoven may include a CD tensile strength peak of 0.5 to 1.9 (N/5 cm)/gsm.

According to certain embodiments, for example, the nonwoven may include a peak in percent MD elongation of 20-50%. In other embodiments, for example, the nonwoven may include a peak in percent MD elongation of 25-45%. In further embodiments, for example, the nonwoven may include a peak in percent MD elongation of 28-40%.

In certain embodiments, for example, the nonwoven may include a peak percent CD elongation of 20-75%. In other embodiments, for example, the nonwoven may include a percent CD elongation peak of 25-60%. In some embodiments, for example, the nonwoven may include a percent CD elongation peak of 30-50%.

In addition to the additives already present in the polylactic acid and polybutylene succinate-based polyesters used in the spunbond nonwoven fibers, the addition of additional additives may also provide additional properties to the fibers. Suitable additional additives include heat stabilizers, light stabilizers, slip additives, waxes, and additives that make the fabric hydrophilic or hydrophobic. The addition of filler materials is sometimes also advantageous. 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 comprise a slip agent. When the first component and the second component of the multicomponent spunbond fibers are made in the form of a masterbatch during the manufacturing process of the fabric, for example during the spinning process, a slip agent is suitably added to these components.

The slip agent to be used according to the invention may be any slip agent that may be suitably used in 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 some incompatibility with the polymer matrix. Suitably, the slip agent may be a hydrocarbon compound or fatty acid derivative having one or more functional groups selected from alcohols, carboxylic acids, aryl and substituted aryl groups, alkoxylates, esters, amides. The slip agent may also be a fatty acid ester of a multivalent 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.

The slip agent is suitably present in an amount in the range of 0.1 to 5% by weight, preferably in an amount of 0.5 to 3% by weight, based on the total weight of the first component. The slip agent is suitably present in an amount in the range of 0.1 to 5% by weight, preferably in an amount of 0.5 to 3% by weight, based on the total weight of the second component.

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

Suitably, one side of the nonwoven layer is provided with a pattern of bonded areas, which defines a pattern of unbonded areas. Preferably, the adhesive areas are personalized adhesive areas, which means that the adhesive areas are arranged separately and not connected to each other. The nonwoven layer may be subjected to an air bonding treatment either before or after the nonwoven layer is provided with a pattern of personalized bonding areas.

Preferably, the side of the nonwoven is provided with only one type of pattern of bonding areas.

Preferably, the adhesive area is a personalized adhesive area having a circular, diamond, rectangular, square, oval, triangular, heart, moon-shaped, bar-shaped, hexagonal, octagonal or another polygonal shape.

Preferably, at least one of the outer sides of the spunbond nonwoven layer is provided with a pattern of individualized 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.

The bonding region may have a circular, diamond, rectangular, square, oval, triangular, bar, heart, moon, hexagonal, octagonal, or another polygonal shape. For example, the pattern of personalized adhesive zones may be various shapes, such as a diamond pattern, a hexagonal dot pattern, an oval-elliptical pattern, a bar pattern, or any combination thereof. Suitably, the pattern of personalized adhesive zones is a continuous pattern.

Suitably, the pattern of individualized bonded areas defines a pattern of unbonded areas whereby the surface of the unbonded 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.

The high surface of the non-adhesive areas to be used according to the invention provides an attractive high softness. In addition, the larger unbonded areas allow the fibers to become fluffy and increase the bulkiness of the fabric. From a visual and tactile point of view this would be perceived as even higher softness.

In a preferred embodiment of the invention, the adhesive area has a diamond, rod, oval or circular shape. More preferably, the bonding region has a diamond or bar shape. Most preferably, the adhesive area has a diamond shape.

Suitably, the maximum width of the adhesive region is suitably 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.

Suitably, the surface of the adhesive area is in the range of 0.38-1.77 mm ², preferably in the range of 0.44-1.22 mm ², more preferably in the range of 0.50-1.13 mm ².

In case the personalized adhesive zone is in the form of an oval, it may be arranged in any direction of the web. Preferably, the adhesive areas in the form of ovals are arranged in such a way that adjacent ovals arranged in the transverse direction each in turn form an opposite angle with the longitudinal direction of the web. The oval shapes may suitably be arranged in such a way that in the machine direction a plurality of uninterrupted regions extend continuously along the web, whereas in the cross-machine direction no uninterrupted regions along the web are present. In the preferred bar arrangement, the width of these uninterrupted regions in the transverse direction is suitably greater than 300 μm, and preferably the width is in the range 500-800 μm.

In another preferred embodiment according to the invention at least one of the spunbond nonwoven layers comprises one side provided with a pattern of alternating individualized bonding areas in the form of bars arranged in the cross-machine direction of the web.

Preferably, the bars are arranged in such a way that in the longitudinal direction of the web there are no uninterrupted regions along the web, whereas in the transverse direction of the web the bars are arranged to define a plurality of uninterrupted regions extending continuously along the web.

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 region in the form of a rod 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.

Preferably, the personalized adhesive zones in the form of bars each form an angle of 90 ° in their length direction with the longitudinal direction of the web. The pattern of the present bonded areas in the form of bars will result in a number of improved fabric properties. Since the fibers are bound substantially perpendicular to their preferred lay-up direction, the transverse tensile strength is significantly improved. It is therefore important that there are no uninterrupted areas in the preferred laying direction (i.e. longitudinal direction) as this will result in weak unbonded fibre areas, resulting in a reduced tensile strength. Furthermore, since there are no uninterrupted regions along the web in the machine direction, the free fiber length (i.e., the average length of the individual fibers between their first and second bonds) is relatively short, resulting in improved wear resistance. Furthermore, this particular bar-shaped arrangement provides uninterrupted non-bonded areas in the transverse direction, thereby significantly reducing the bending forces of the fabric and translating into excellent drape without sacrificing mechanical strength. This finding is surprising, as these two properties are often mutually exclusive.

The rod shape may have flat and/or curved ends. Preferably, the curved end has a circular shape. Preferably, the rod shape has a linear shape. Suitably, the length of the personalized adhesive zone in the form of a stick is 2-10 times, preferably 2-8 times its width.

The depth of the discrete non-bonded regions between the rod shapes 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.

Suitably, the distance between each pair of adjacent bars 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 bars in the longitudinal direction is in the range 2.5-5.0 mm, preferably 3.3-4.2 mm

When the personalized adhesive zone 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.

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.

The invention also relates to a method for producing a nonwoven fabric according to the invention, comprising the following steps

(A) Providing a flow of molten or semi-molten polylactic acid;

(b) Providing a molten or semi-molten polylactic acid and a molten or semi-molten polybutylene succinate-based polyester blend stream;

(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 a molten or semi-molten polybutylene succinate-based polyester blend stream, the multicomponent spunbond fibers comprising a first component comprising a single polymer composition comprising polylactic acid and a second component comprising a polymer blend composition comprising polylactic acid and polybutylene succinate-based polyester, wherein the first component is present in an amount in the range of 50 to 80 weight percent and the second component is present in an amount in the range of 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).

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

In step (c), a fiber draw speed of greater than 2500 m/min may suitably be applied. In other embodiments, for example, fiber drawing may be performed at a fiber drawing speed of 3000 to 4000 m/min. In other embodiments, for example, the process may be performed at a fiber draw speed of 3000 to 5000 m/min.

The nonwoven web obtained in step (d) may be bonded to form the present nonwoven, which bonding may include thermal point bonding of the web with heat and pressure via a calender having a pair of cooperating rolls including a patterned roll. In such embodiments, for example, thermally point bonding the web may include imparting a three-dimensional geometric bond pattern to the present nonwoven. The patterned roll may include a three-dimensional geometric bond pattern. In the bonding pattern, the bonding areas may suitably be personalized bonding areas having a circular, diamond, rectangular, square, oval, triangular, heart, moon-shaped, stick, hexagonal, octagonal or another polygonal shape.

The calender may include a release coating to minimize deposition of molten or semi-molten polymer on the surface of one or more rolls. Such release coatings are described, for example, in European patent application 1,432,860, which is incorporated herein by reference in its entirety.

The method according to the invention may further comprise dissipating static charge from the nonwoven close to the calender via the static control unit. In some embodiments, for example, the electrostatic control unit may comprise an ionization source. In further embodiments, for example, the ionization source may comprise an ionization bar. However, in other embodiments, for example, dissipating static charge from the nonwoven fabric may include contacting the nonwoven fabric with an electrostatic wand.

The method may further 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 comprise an ionization bar.

The method may further comprise increasing the moisture content while forming a plurality of continuous multicomponent spunbond fibers. In such embodiments, for example, increasing the humidity may include applying at least one of steam, mist, steam, or any combination thereof to the plurality of continuous multicomponent spunbond fibers.

The present nonwoven fabric may be produced, for example, by conventional spunbond processes on a spunbond machine such as, for example, the Reicofil-3 or Reicofil-4 line from the Reifenh ä user, as described in U.S. Pat. No. 5,814,349 to Geus et al, wherein the molten fiber component is extruded into continuous multicomponent spunbond fibers which are subsequently quenched, attenuated pneumatically by high velocity fluid, and collected on a collection surface in a random arrangement. In some embodiments, the continuous fibers are collected by means of a vacuum source located below the collection surface. After filament collection, any thermal, chemical or mechanical bonding process may be used to form the bonded web, resulting in a bonded web structure. Examples of thermal bonding may include bonding by air, where hot air is forced through the web to soften the polymer outside of some of the fibers in the web, followed by at least limited compression of the web, or calender bonding, where the web is compressed between two rolls, where at least one roll is heated, and typically one roll is an embossing roll, as will be appreciated by those skilled in the art.

In some embodiments of the present method, the collection surface may comprise conductive fibers. The conductive fibers may include monofilaments made of polyamide (e.g., huycon-LX 135) conditioned polyethersulfone. In the machine direction, the fibers comprise polyamide-modified polyethersulfones. In the cross-machine direction, the fibers comprise a polyamide-modified polyethersulfone in combination with an additional polyethersulfone.

The non-woven fabric can be used for preparing various structures. For example, in some embodiments, the present nonwoven may be combined with one or more additional layers to produce a composite or laminate. Examples of such composites/laminates may include spunbond composites, spunbond-meltblown (SM) composites, spunbond-meltblown-Spunbond (SMs) composites, or spunbond-meltblown-spunbond (SMMS) composites. In some embodiments, a composite comprising a layer of the nonwoven fabric of the present invention and one or more film layers may be prepared.

The present invention also provides a nonwoven fabric comprising at least two nonwoven spunbond layers and one or more meltblown nonwoven layers, the two nonwoven spunbond layers each comprising spunbond fibers and the one or more meltblown nonwoven layers each comprising meltblown fibers, wherein the one or more meltblown nonwoven layers are disposed between the spunbond nonwoven layers, wherein the spunbond fibers of the spunbond nonwoven layers are multicomponent 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-based polyester, wherein the first component is present in an amount in the range of 50-80% by weight and the second component is present in an amount in the range of 20-50% by weight, both amounts being based on the total weight of each multicomponent spunbond fiber, and wherein the polybutylene succinate-based polyester is present in an amount in the range of 0.2-5% by weight, based on the total weight of each multicomponent spunbond fiber.

In such multilayer nonwoven embodiments, at least one of the meltblown layers further comprises polylactic acid.

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

Spunbond fibers are generally continuous and have fiber diameters in the range of 10 to 100 microns, preferably 10 to 50 microns, more preferably 10 to 35 microns, and most preferably 10 to 30 microns.

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

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

The multilayer structure according to embodiments may 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 may 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 point bonded to one another by passing the multilayer structure through a pair of calender rolls.

The invention also provides an absorbent article. The absorbent article comprises a nonwoven fabric according to the invention. In one embodiment, a sustainable composite comprising at least two nonwoven layers may be provided such that at least one nonwoven layer comprises one layer of the present nonwoven. The nonwoven fabric layer comprises a plurality of multicomponent spunbond fibers wherein a polybutylene succinate-based polyester and PLA are present at the surface of the plurality of multicomponent spunbond fibers.

The present nonwoven fabric may be used in a variety of articles and applications. For example, embodiments of the present invention may be used in personal care applications, such as baby care products (diapers, wet wipes), feminine care products (pads, napkins, tampons), adult care products (incontinence products), or cosmetic application products (cosmetic tampons). Other possible uses include agricultural applications (e.g., root wraps, seed bags, crop covers), industrial applications (e.g., work wear, airline pillows, car trunk liners, sound insulation), and household products (e.g., mattress spring covers and furniture scratch pads).

When the absorbent article is a diaper comprising an absorbent core sandwiched between a facing and a backing, one or both of the facing and backing may comprise the present nonwoven and/or a sustainable composite comprising the present nonwoven layer. The facecloth will be positioned adjacent to the outer surface of the absorbent core and preferably attached to the absorbent core and the backing cloth by attachment means such as are known in the art. For example, the facecloth may be secured to the absorbent core by a uniform continuous adhesive layer, a patterned adhesive layer, or an array of separate adhesive lines, spirals, or spots.

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

Examples

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

Test method

The titre (Titer) was calculated from microscopic measurements of the fiber diameter and the known polymer density according to German textile method C-1570.

Basis weight is generally determined from the weight of 10 layers of fabric cut into 10 x 10 CM squares according to the german textile method CM-130.

The stretching was determined according to method 10 DIN 53857 using samples of 5 cm wide, 100 mm gauge length and 200 mm/min crosshead speed. The tensile strength peak was measured.

The elongation was determined according to method 10 DIN 53857 using samples of 5 cm wide, 100 mm gauge length and 200 mm/min crosshead speed. The elongation peak was measured.

Tensile strength and elongation are determined under both dry and wet conditions. Under wet conditions, the nonwoven fabric was wetted with water.

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) is located on the collecting surface downstream of the location where the fibers are deposited on the collecting surface. The fibers were bicomponent 30/70 PLA NatureWorks grade 6202/PLA NatureWorks grade 6202/sheath/core. PLA Nature works grade 6202 has 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 ℃.

The nonwoven of comparative example 1 was produced at a spinning beam temperature of 235 ℃ at the extruder (spin beam temperature) and at 235 ℃ at the die. The nonwoven fabric of comparative example 1 was produced at a throughput of 270 kg/h and a cabin pressure of 4800 Pa. The pattern roll of the calender of comparative example 1 had a calendering temperature of 125 ℃, the anvil roll had a calendering temperature of 125 ℃, and the calendering pressure was 40N/mm. The bonded regions had a diamond shape with a fiber denier of 2.65 dtex and a nonwoven fabric basis weight of 28.5 gsm.

Inventive example 1

In example 1 of the present invention, the nonwoven fabric was made of bicomponent fibers having a 30/70 sheath/core structure. The masterbatch to make the sheath included PLA resin (Naturworks grade 6202) to which was added 3% by weight polybutylene succinate (BioPBS FZ. Mu.m/PTT MCC Biochem). BioPBS FZ78TM/PTT MCC Biochem has a melt flow rate of 22 g/10 min (determined according to ASTM D1238 (190 ℃ C., 2.16 kg)) and a melting point of 115 ℃. The system setup was the same as described above for comparative example 1. The nonwoven fabric of example 1 of the present invention was produced at an extruder at a spinning beam temperature of 235 ℃ and at a die at a spinning beam temperature of 235 ℃. The nonwoven fabric of example 1 of the present invention was produced at a throughput of 270 kg/h and a cabin pressure of 4500 Pa. The pattern roll of the calender of example 1 of the present invention had a calendering temperature of 161 ℃, the anvil roll had a calendering temperature of 161 ℃ and a calendering pressure of 40N/mm. The bonded regions had the same diamond shape as in comparative example 1, the fineness of the fibers 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.

TABLE 1

TABLE 2

As can be seen from tables 1 and 2, the nonwoven fabric according to the present invention showed a significant improvement in mechanical properties compared to comparative example 1 using the same prepared PLA nonwoven fabric excluding polybutylene succinate. Based on this data, it can be seen that the nonwoven fabric of the present invention exhibited an increase in tensile strength of greater than 50% as compared to comparative example 1. Table 1 shows that the nonwoven fabric according to the invention shows a significant increase in MD tensile strength and CD tensile strength.

In addition, table 2 shows that the nonwoven fabric according to the invention exhibits a significant increase in MD elongation, CD elongation.

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 for wet wipe applications.

As is clear from tables 1 and 2, when a small amount of PBS (3 wt.%) was used in the sheath component, a significant increase in tensile strength and elongation was obtained, as compared with the sheath component made of PLA alone.

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 surfaces of comparative example 1 and inventive example 1 were obtained. Fig. 1 and 2 are SEM images of comparative example 1 and example of the present invention, respectively, taken at 200 x magnification. These images were obtained using a Keyence VHX digital microscope.

A significant difference in adhesion between the fibers was observed. In particular, the bond points of the fabric of comparative example 1 indicate that the individual fibers are loosely bonded together and that there is minimal polymer flow bonding adjacent fibers to each other. In contrast, the bond points of the fabric of example 1 of the present invention indicate significant melting and flow of the polymer of the individual fibers. Thus, the present nonwoven exhibits a significant improvement in adhesion as compared to a comparative nonwoven that does not include a small amount of polybutylene succinate.

As is clear 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 adhesive ability, as compared with comparative example 1 including PLA resin in the sheath component but not including PBS.

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 multicomponent 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 in the range of 15-45 g/10 min as determined according to ASTM D1238 (210°C, 2.16 kg), and the polymer blend composition comprises polylactic acid having a melt flow rate in the range of 15-45 g/10 min as determined according to ASTM D1238 (210°C, 2.16 kg) and polybutylene succinate-based polyester having a melt flow rate in the range of 15-35 g/10 min as determined according to ASTM D1238 (190°C, 2.16 kg).

8. The nonwoven fabric according to any one of claims 1 to 7, having a basis weight of less than 50 g/ ^m2 .

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 bond 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 % and the second component is present in an amount ranging from 20 to 50 wt % 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 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.