Elastic nonwoven sheet

Abstract

To provide elastically stretchable nonwoven sheets comprising an elastically stretchable nonwoven layer and a stretchable facing layer, and an in-line method for making such sheets.SOLUTION: An elastically stretchable nonwoven sheet comprises at least three layers of nonwoven materials, wherein one layer is one of the three layers and is an elastically stretchable nonwoven material comprising spunbonded elastic fibers formed from a thermoplastic elastomer polymer material, and the other layer is two of the three layers and is a stretchable facing layer comprising spunbonded crimped multi-component fibers. The elastically stretchable nonwoven sheet is further configured to sandwich the elastically stretchable nonwoven material between the two facing layers. The three adjacent layers are embossed with protrusions placed on the surface of at least one calender roll and are joined to each other by areal bonding points, which is done by ultrasonic vibration of the protrusions for embossing or by heating the protrusions for embossing.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an elastically stretchable nonwoven fabric comprising an elastically stretchable nonwoven elastic layer and a stretchable nonwoven decorative layer. Stretchable nonwoven sheets and in-line processes for producing such sheets Regarding. [Background technology]

[0002] Nonwoven sheets are used in the hygiene industry to make baby diapers and adult incontinence products. However, in many cases, for example, the back ears of open diapers Elastically stretchable material for forming the waist belt portion of a diaper or pants type. A material is required, but general nonwoven sheets cannot meet this requirement.

[0003] Conventional methods to address the problem of limited elastic elongation of nonwoven sheets include: Elastic layers may be placed between layers of nonwoven material, thereby providing the resulting laminate with elastic properties. However, the elastic layer is not breathable and may cause discomfort to the wearer. One way to do this is to include elastic strands, commonly called Lycra fibers, in the sheet. The problem with this method is localized elastic forces that can cause discomfort to the wearer and can be easily distorted during manufacturing. The problem is that the strands are prone to breakage.

[0004] Additionally, the sheet is made elastic by including elastic layers or strands. The elasticity remains within the maximum elongation range of the nonwoven material associated with the elastic layer or strand. Most conventional nonwoven materials have a maximum, and in most cases even less, flow rate. Approximately 50 to 80% in the machine direction (MD) and 70% in the cross-machine direction (CD). It has an elongation at break of 100% (WSP110.4), which means it can be stretched very easily before breaking. However, for the above mentioned applications, The material can elastically stretch from 150% of its original dimension (up to 250% of its original dimension) depending on the specific application. This corresponds to stretching in the direction perpendicular to the flow or in the flow direction. For example, to manufacture conventional open or tape-type baby diapers, In a typical manufacturing process, the material used for the back ears has a resilience of the above values ​​in CD. On the other hand, manufacturers of pants-type diapers for adults and babies are required to have high elongation. In order to achieve this, the materials used in elastic applications such as belts are typically It is required to exhibit the above-mentioned elastic elongation in the MD.

[0005] Conventional methods to address the limited stretchability of nonwoven materials include the use of elastic layers or The nonwoven sheet may be folded and pleated during lamination to the strands. compensates for the lack of stretch in the nonwoven material itself by providing additional material in the pleats. However, the drawback of pleating is that it requires a lot of material during production and the final product is thicker. This makes them highly insulating and conspicuous, making them unpopular with buyers.

[0006] More recent approaches involve the use of nonwoven materials that are inherently elastically stretchable. The sheet comprises at least one nonwoven fabric that is stretchable but not very elastic itself. and an elastic nonwoven layer.

[0007] An offline process for producing such elastically stretchable nonwoven sheets is described in WO2020 This method is disclosed in US Pat. No. 6,275,400. This method involves preparing pre-fabricated fibers from crimped fibers. The decorative layer is used, and the decorative layer is formed in the spunbonding process to form the spunbond elastic layer. The sheet is then pre-stretched with a pair of corrugated rollers. The resulting product can be elastically stretched in CD to more than 150% of its original dimension. Although it meets industrial requirements, it is clear that there is a limit to the elastic elongation in the MD. It has been found that the applied decorative layer loses a lot of its elasticity when passed through the production line a second time. Therefore, the possibility of further increasing elongation in MD is limited in offline processes.

[0008] An in-line process for producing elastically stretchable nonwoven sheets is disclosed in EP 3715517 A1. This method uses a multi-beam spunbond line to separate crimped fibers. A sheet having a stretchable decorative layer made of the above-mentioned material and an elastic layer made of elastic fibers is formed by calendering the material. - Manufactured on the same line before bonding and pre-stretching. The product obtained in this process is It has sufficient stretchability in MD, but lacks sufficient stretchability in MD. do.

[0009] Therefore, nonwoven sheets with high inherent elastic stretchability in the machine direction are suitable for use in the hygiene industry. is still required. Summary of the Invention [Problem to be solved by the invention]

[0010] Here, the present invention provides an elastically stretchable nonwoven sheet comprising at least two layers of nonwoven material. One of the two layers is a spatula made of a thermoplastic elastomer polymer material. An elastically stretchable nonwoven material having spunbonded elastic fibers, and the other layer is spunbonded. A stretchable decorative layer having crimped multicomponent fibers, wherein adjacent layers are embossed. The crimped multicomponent fibers are joined by junctions, and at least one of the components is propylene- It is an α-olefin copolymer material.

[0011] Compared with the nonwoven sheet disclosed in EP3715517A1, both of the composite fibers in the decorative layer Polypropylene is used as one component of the composite fiber, and propylene is used as at least one component of the composite fiber. By using olefin-α-olefin copolymer (co-PP), it is possible to The overall elasticity of the sheet is significantly increased in the MD. When measured according to 00.4, such sheets have a thickness of more than 150%, preferably The target elongation at break is over 200%. [Means for solving the problem]

[0012] The sheet according to the invention preferably exhibits advantageous elastic behavior, especially in the machine direction.

[0013] In one embodiment, the tensile strength measured according to ASTM D5459 after the first cycle is The permanent deformation in the machine direction is less than 15%, preferably less than 10%, more preferably less than 5%. be.

[0014] In one embodiment, the hysteresis loop in the second cycle of the ASTM D5459 test The area between the increasing and decreasing flow-direction stress-strain curves in the SIS plot is the initial increasing curve. It is expressed as the relative size of the area between the curves (A) in relation to the total area under (A+B). In other words, it is less than 40%, and preferably less than 30%.

[0015] The two or more components of a bicomponent fiber are asymmetrically arranged in the cross section of the fiber. In an embodiment, the multicomponent fiber is a bicomponent fiber. However, the concept of the present invention is not limited to parallel fibers, and may be applied to other fibers such as eccentric fibers. It may also be realized in other cross sections such as sheath-core.

[0016] The nonwoven materials of both the decorative layer and the elastic layer are spunbond nonwoven materials, and the nonwoven sheet is In principle, it is preferable that the sheet is a spunbond nonwoven sheet.

[0017] The α-olefin that forms the copolymer with propylene is preferably ethylene. In other words, the copolymer is preferably a poly(propylene-ethylene) copolymer. Likewise, the copolymer is preferably a random copolymer.

[0018] The comonomer content in propylene-α-olefin copolymers, or poly(pro The ethylene content in the pyrene-ethylene copolymer is preferably 1 wt.-% or more. %, more preferably 2 wt.-% or more. As an upper limit, the comonomer content is 8 wt.-% or less. It may be up to t.-%, preferably up to 6 wt.-%.

[0019] Another component of the crimped multicomponent fiber is preferably a polypropylene homopolymer (P As used herein, polypropylene homopolymer has a monomer purity of 99.5 wt. .-%, preferably higher than 99.8 wt.-%, more preferably higher than 99.9 It is understood as being higher than wt.-%.

[0020] Polypropylene is one component and poly(propylene-ethylene) copolymer is the other component. It can be seen that the use of composite fibers as a .

[0021] In a further preferred embodiment, the polydispersity (M w / M n ) represented by propylene-α The molecular weight distribution of the -olefin copolymer is broader than that of the other components of the crimped multicomponent fiber. Preferably, the molecular weight distribution of the polypropylene homopolymer used in the other component of the composite fiber is It is wider than.

[0022] From the viewpoint of number, the M of two polymers w / M n The difference is preferably 1 or more, More preferably, it is 2 or more, and most preferably, it is 3 or more. w / M n The difference between M is preferably 10 or less, and preferably 8 or less. w / M n The appropriateness Typical absolute values ​​are, for example, 2.5 to 7.5 for polypropylene and propylene-α-olefins. For olefin copolymers it can be 4 to 10.

[0023] The components of the multicomponent fiber, co-PP or homo-PP, are either polymerized with another polymer or It may be mixed with other additives such as slip agents, fillers or color masterbatches, but More than 50% by weight of each component, preferably more than 75%, and more preferably more than 90% Exceed.

[0024] In the crimped bicomponent fiber, the weight ratio of the co-PP component to the other components is preferably The homo-PP content of the fiber is between 20 / 80 and 80 / 20, more preferably 30 / 70. Between 70 / 30, and more preferably between 40 / 60 and 60 / 40.

[0025] The thermoplastic elastomer material for forming the elastic fiber is a thermoplastic polyolefin elastomer. The polymer (TPE-o) preferably has a propylene-α-olefin copolymer. Suitable materials for use in the context of the present invention include thermoplastic polyolefin elastomers. Such TPE-o materials are disclosed in EP 2342075 A1. Alternatively, or in addition, In addition, in the sense of a blend, other thermoplastics, such as thermoplastic polyurethanes (TPU), Plastic elastomer materials or styrene block copolymers (TPE-s) may also be used. In one embodiment, up to 20 wt.-% of the thermoplastic elastomer, preferably Thermoplastic elastomers containing up to 10 wt.% of thermoplastic olefins such as homopolypropylene It may also contain fillers, slip agents, color masterbatches, etc. In some embodiments, the composite elastic fibers may be in a side-by-side or may be formed from two different thermoplastic elastomers arranged in a sheath-core configuration.

[0026] The elastic layer and the decorative layer of the sheet are made of the above-mentioned elastic material or composite material in addition to other fibers. It may comprise fibers, but preferably consists solely of the above-mentioned elastic or bicomponent fibers.

[0027] In one embodiment, the sheet has at least one decorative layer on each side of the elastic layer, This results in a total of at least three layers. It is advantageous to cover the elastic layer of the

[0028] In embodiments, another cosmetic layer may be configured as described above as the first cosmetic layer. The decorative layers provided on different sides of the elastic layer may be the same or different. For example, one nonwoven decorative layer may be a spunbond nonwoven material and the other nonwoven decorative layer may be a It may also be another spunbond or meltblown nonwoven material.

[0029] The basis weight of each decorative layer is 5 to 40 g / m 2 and preferably from 8 to 30 g / m 2 , more preferably 10 to 25 g / m 2 , more preferably 15 to 20 g / m 2 is. The basis weight of the elastic layer is 10 to 140 g / m 2 Preferably, the weight of the mixture is 20 to 120 g. / m 2 , more preferably 25 to 100 g / m 2 is.

[0030] The sheet typically has a pattern of macroscopic bonds. 1cm of the fiber surface 2 The number of junctions per Preferably, the surface bond points are less than 80 and more than 20. The total area of ​​the fiber surface that is covered by the adhesive is less than 18%, preferably less than 15%. This means that the mesh pattern is preferably relatively open.

[0031] In one embodiment, the sheet of the present invention has a property of being naturally stretchable in the machine direction. Further activation is achieved by prestretching in the direction of flow, as explained in more detail below. That's fine.

[0032] The present invention further provides a method for producing the elastically stretchable nonwoven sheet according to the present invention. The method includes the following in-line steps: (a1) at least one component is propylene glycol; The crimped multicomponent fibers are spun from a moving spin belt. (a2) placing a thermoplastic elastomer polymer material on a substrate to form a woven fabric; The elastic fibers are spun, and the fibers are placed on the surface of the woven fabric formed in step (a1) to form another woven fabric. (b) bonding adjacent woven fabrics to form an elastically stretchable spunbond nonwoven sheet. and forming a port.

[0033] The spinning steps (a1) and (a2) include extruding fibers in a spunbonding machine; The fibrous woven fabric formed in step (a1) is subjected to a bonding process. The nonwoven material for forming the decorative layer and the elastic layer of the nonwoven sheet after step (b) is bonded to the nonwoven material. It is an uncombined precursor.

[0034] The bonding in step (b) is most preferably embossed. Specifically, the bonding is performed by smashing the joining points. embossing the sheet of at least one calender roll, This is achieved by embossing protrusions located on the surface. Embodiments include ultrasonic bonding. Ultrasonic vibrations are applied to the embossing projections. In another embodiment, the embossing projections are heated. Thermal bonding is used.

[0035] In a preferred variant, 1 cm of the fiber surface 2 The number of junctions per The total area of ​​the fiber surface occupied by the surface junctions is preferably less than 18%, preferably More preferably, it is less than 15%, meaning that the bonding pattern is relatively open.

[0036] In one embodiment, the method further comprises spinning another fiber, preferably a crimped multicomponent fiber. Step (a3) ​​is further provided, and most preferably at least one of the components of the crimped multicomponent fiber. is a propylene-α-olefin copolymer, and the woven fabric formed from this fiber in step (a2) In a variation of this method, the preferred A sheet according to a preferred embodiment is provided, and a sandwich structure of an elastic layer provided between two decorative layers is provided. Has.

[0037] In one embodiment, the method further comprises pre-compressing the woven fabric of the decorative layer. Each corresponding step is followed by one pre-compression step, i.e. step (a1) and, if applicable, Preferably, the pre-compression step includes a step (a3) ​​of compressing the woven fabric into two pre-compression layers. This involves passing the material through compression rollers. The linear pressure applied is preferably 3 to 5 N / mm. The roller temperature may be 50 to 110°C or higher, more preferably 60 to 110°C. 00°C. Due to the inherent tackiness of the thermoplastic elastomer fibers, pre-compression is Step (a2) is not necessary or feasible after that.

[0038] In one embodiment, the method further comprises the step (c) of pre-stretching the sheet in the machine direction. Prepare.

[0039] Pre-stretching in the machine direction can be achieved, for example, by pulling the material in the machine direction with a pair of rollers at different speeds. This can also be done as follows.

[0040] Alternatively, pre-stretching in the machine direction can be achieved by interlocking annular ribs and grooves (ring rolls) or A pair of interlocking rolls having ribs and grooves on their surfaces in a direction perpendicular to the flow direction. This may be accomplished by mechanically activating the sheet in a mill equipped with a

[0041] The machine direction pre-stretching step (c) may be carried out in-line or as a stand-alone process. You can do this.

[0042] The extent of pre-stretching of the sheet in the machine direction in step (c) is such that the final sheet Therefore, in one embodiment, in step (c ) the sheet is pre-stretched in the machine direction. The degree of pre-stretching in the machine direction can be, for example, The sheet is 40 to 160% of its original dimensions, preferably 60 to 140%, more preferably 8 It can stretch from 0 to 120%.

[0043] In another embodiment, the method does not include pre-stretching in the machine direction. Since the pre-stretching in the machine direction is specifically selected, the pre-stretching in the machine direction is favorable compared to prior art materials. In some cases, it may not be necessary to obtain the desired elongation properties.

[0044] The present invention is not limited to two- or three-ply sheets. Elastic or decorative or non-elastic. By providing additional layers, three or more layers may be formed. Two or more sub-layers of the same or similar type formed from different stages of fibre may be provided. [Effects of the Invention]

[0045] The nonwoven sheets according to the present invention are particularly suitable for use in the manufacture of hygiene products. The sheet is used in the manufacture of pants-type diapers with a sheet used as an elastic waist material. Typical manufacturing processes currently employed in industry for this application include requires that the material be elastically stretchable in the MD.

[0046] Further details and advantages of the invention will become apparent from the drawings and examples described below. It will be. [Brief explanation of the drawings]

[0047] [Figure 1] 1 is a schematic cross-sectional view of an elastically stretchable nonwoven sheet according to the present invention. [Figure 2] An example of a machine configured to carry out the method of the present invention [Figure 3] Schematic of the unit that activates sheets by stretching in the machine direction [Figure 4] Schematic diagram of the unit shown in Figure 3 in operation [Figure 5] MD tensile (stress-strain) curves of separated spunbond decorative layers according to the comparative example configuration [Figure 6] MD Tensile (Stress-Strain) Curves of Separated Spunbond Decorative Layers According to the Construction of the Invention [Figure 7] MD Tensile (Stress-Strain) Curve of Another Separate Spunbond Decorative Layer According to the Construction of the Invention [Figure 8] MD tensile (stress-strain) curves of separated elastic spunbond nonwoven layers [Figure 9] MD tensile (stress-strain) superposition curves of the sheet according to the present invention, the separated decorative layer of the sheet, and the separated elastic layer of the sheet [Figure 10] Schematic of a tensile (stress-strain) diagram and subsequent stress-strain cycle ramp-up and ramp-down curves showing ASTM D5459 testing [Figure 11] Machine direction tensile (stress-strain) plot for Sample 5-1 of Example 5 showing the hysteresis curve of the material DETAILED DESCRIPTION OF THE INVENTION

[0048] FIG. 1 shows a schematic cross-sectional view of an elastically stretchable nonwoven sheet 100 according to the present invention. An elastic nonwoven layer comprising fibers 130 is sandwiched between first and second nonwoven decorative layers 120 .

[0049] A machine set up to produce the elastically stretchable nonwoven sheet 100 of the present invention An example is shown in Figure 2.

[0050] This setup consists of a conveyor belt 10 and three spunbond rollers inline with the conveyor belt. The apparatus is equipped with machines 20, 30 and 40.

[0051] In each spunbond machine, molten thermoplastic polymer is extruded through holes in a die. The extruded fiber strands are then quenched and drawn / stretched to form endless fibers. The endless fiber thus formed is deposited on the conveyor belt 10 or on the conveyor belt 10 in advance. It is placed on a pile of woven fabric.

[0052] The first spunbond machine 20 deposits a woven fabric of crimped composite fibers onto the conveyor belt 10. The polymer feed is shown above the first spunbond machine 20. The middle spunbond machine 3 0 deposits a woven fabric made of thermoplastic elastomer onto the preformed fabric. The spunbonder 40 deposits another woven fabric of crimped composite fibers onto the elastic fiber woven fabric. Next to the rollers 20 and 40, a pair of pre-compression rollers 21 and 41 pre-compress the woven fabric. Each is provided.

[0053] The pre-compressed woven fabric is then passed through a curing machine comprising a pair of counter-rotating embossing rollers 51 and 52. The nonwoven fabric is then calendered in a calender unit 50 to form a nonwoven sheet. Then, a pair of counter-rotating activation rollers 61 having interlocking structural elements on their surfaces, which will be described in more detail below. The activation step is carried out in an activation unit 60 comprising a 62 and a 63. Finally, the product sheets are collected into a product roll 70.

[0054] FIG. 3 shows an activation row of an activation unit 60 configured to enhance elasticity in the flow direction. 3 shows an embodiment of rollers 61 and 62. Specifically, the view shown in FIG. Both rollers 61 and 62 are aligned along their radial planes. The working surface is provided with a plurality of ribs 63 evenly spaced apart, with grooves 65 formed between the ribs 63. The ribs 65 are arranged perpendicular to the flow direction, and the rollers 61 and 6 The width of the rib 63 is designated "a" and the depth of engagement is designated "b". , the distance between adjacent ribs is represented by "c".

[0055] Figure 4 shows the unit shown in Figure 3 in operation. From left to right in Figure 4, there are two decorative layers and a decorative layer sandwiched between the elastic layer and the unactivated precursor sheet, which is then subjected to an activation step. When the sheet enters the nip between the two rollers 61 and 62, the sheet is caught by the interlocking rib 6 During this process, the elastic layer is stretched partially between the The parameters "a", "b" and "c" are given to the nonwoven sheet. This may be varied as needed depending on the elongation properties that may be obtained and desired.

[0056] Even without activation, the crimped composite fibers have a relatively narrow molecular weight distribution. propylene homopolymer and ethylene-propylene random copolymer with a relatively broad molecular weight distribution By using a combination with a copolymer, it is possible to significantly increase the flow rate without breaking in the flow direction. It was found that a sheet that can be stretched up to 300% can be achieved. This is the industrial standard. and is sufficient to match the high elongation characteristics of the elastic nonwoven layers used in the sheets of the present invention. and in embodiments can elastically stretch 400 to 500%.

[0057] The advantageous properties of the sheets of the present invention are illustrated in the following examples.

[0058] Many spunbond decorative layers using parallel composite crimped fibers are prepared using the materials specified below. I prepared it.

[0059] [Table 1]

[0060] The 511A polymer is manufactured by Sabic and has a narrow polymer weight distribution (M w / M n is 3.8) , MFR of 25g / 10min and T of 161℃ m It is a polypropylene homopolymer having do.

[0061] HP552N polymer is a wide polymer weight distribution (M w / M n 6.8), MFR of 13 g / 10 min and T of 161 °C m Polypropylene having It is a homopolymer.

[0062] RP248R polymer is a 30g / 10min MFR, intermediate grade polymer manufactured by LyondellBasell. Molecular weight distribution (M w / M n 5.2) and T of 148°C m Ethylene-propylene copolymer having The composition is a polyaniline random copolymer and further comprises a cleaning agent and a slip agent.

[0063] QR674K polymer is manufactured by Sabic, and has a MFR of 40g / 10min, a wide molecular weight distribution ( M w / M n 8.5) and T at 150°C m Ethylene-propylene random copolymer having It is a combination and further comprises a cleaning agent and a slip agent.

[0064] The melt flow rate (MFR) in this specification is measured at 230°C and 2.16 kg. It is understood to be determined in accordance with ISO 1133.

[0065] The melting temperature (T m ) is determined by DSC according to ISO 11357-3 It is understood that

[0066] The molecular weight average (M w and M n ) and molecular weight distribution (MWD, M w / M n ) result value is calculated using the following formula, ISO16014-1:2003, ISO16014 -2:2003, ISO16014-4:2003 and ASTM D 6474-12 It is understood that the solubility is determined by GPC according to Equation 1.

[0067] JPEG0007764529000002.jpg47170

[0068] Fixed elution volume interval ΔV i In contrast, A i and M i are the elution amounts V i Related to is the chromatographic peak slice area and the polyolefin molecular weight (MW), and N is the integral It is equal to the number of data points obtained from the chromatograph between the limits.

[0069] Infrared (IR) detector (PolymerChar) (Valencia, Spain) High-temperature GPC instrument with IR4 or IR5 manufactured by Agilent, or 3x Agilent- PLgelOlexis and 1x Agilent-PLgelOlexisGuard An Agilent Technologies differential refractometer (RI) equipped with a column was used. and 250 mg / L 2,6-di-t-butyl-4-methyl-phenol as the mobile phase) 1,2,4-Tricyclobenzene (TCB) stabilized with HCl was used. The filter system was operated at 160 °C and a constant flow rate of 1 mL / min. The polymer solution was injected for each analysis. Data collection was performed using PC-IR control software.

[0070] 19 thin MWD polysilicon films ranging from 0.5 kg / mol to 11,500 kg / mol Universal calibration with styrene (PS) standard (ISO16014-2:20 The column set was calibrated using a PS standard (based on HPLC). The polystyrene peak molecular weight can be converted to a polyolefin molecular weight as follows: This is achieved by using the Mark-Hwink formula and the following Mark-Hwink constants: K PS =19×10 -3 mL / g, a PS =0.655 K PE =39×10 -3 mL / g, a PE =0.725 K PP =19×10 -3mL / g, a PP =0.725 A third order polynomial fit was used to fit the calibration data.

[0071] All samples were prepared in a concentration range of 0.5 to 1 mg / ml and were incubated at 160°C for 2.5 hours. It dissolved in a short time.

[0072] Table 2 below shows the results of the separated 20 gsm spunbond decorative sheets obtained from these materials. The characteristics obtained for the sintered material are shown.

[0073] [Table 2-1]

[0074] [Table 2-2]

[0075] In particular, none of the samples were activated in the mills shown in Figures 3 and 4, and the 1 cm 2 Around It had an open dot binding pattern with 24 binding sites and a binding area of ​​12%. .

[0076] Example 1 is a comparative example. Examples 2 and 3 are examples of the present invention. Comparative Examples 1 to 3 The MD tensile (stress-strain) curves of the samples are shown in Figures 5 to 7, respectively. 5 and 6 show the curves of multiple measurements that have then been averaged, and FIG. 7 shows the curves of measurements that have already been averaged. Only the curves that were selected are shown.

[0077] As is clear from the values ​​in Table 2 and the curves in Figures 5 to 7, the MD elongation of the decorative layer in Example 2 was The elongation of the decorative layer is very high (about 20% higher) compared to that of Comparative Example 1. Molecular weight distribution of Co-PP In particular, in Example 3, the difference in MWD between PP and Co-PP is larger than in Example 2. The cosmetic layer according to the preferred configuration has a very high effect (an additional 80% improvement). MD elongation at break values ​​of nearly 200% despite not being stretched / pre-stretched (Example 2) Furthermore, values ​​exceeding 250% (Example 3) generally indicate that the fiber arrangement is mainly in the machine direction. It is also worth noting that the thickness of the decorative layer is Although often related to the level of crimp to some extent, the thickness of the decorative layer in Examples 2 and 3 However, the thickness of the decorative layer is smaller than that of Comparative Example 1 despite the same basis weight. The level of simple crimping affects the ability of the spunbond decorative layer to stretch in the machine direction. It is clear that there are other effects beyond the bell.

[0078] Next, as Example 4, an elastic sheet sandwiched between two decorative layers constructed according to the present invention was used. Three sheets of the present invention (Samples 4-1, 4-2 and 4-3) having a spunbond layer were prepared. 2. The same procedure as in FIG. 2 was followed except for the mill for activating the material (sheets that remained unactivated). These layers were prepared and configured as specified below: Sample 4-1, 4-2 and 4-3 differ only in the basis weight of the layers.

[0079] [Table 3]

[0080] Both decorative layers of the sheet of Sample 4-1 were confirmed by the separate method in Example 3. The bonding pattern is as described for the separate decorative layers.

[0081] The elastic layer has an ethylene content of 13 wt.% and a melt flow rate of 45 g / 10 min. A single propylene-based thermoplastic elastomer copolymer manufactured by ExxonMobil. Commercially available TPE-o material Vistamaxx TM The bonding pattern is: As mentioned above.

[0082] Table 4 below shows the properties determined for the three samples of Example 4.

[0083] [Table 4-1]

[0084] [Table 4-2]

[0085] As a modification of Example 4, in another Example 5, as shown in Figs. The same material as in Example 4 was produced, except that it was pre-stretched in the direction and activated in activation unit 60. Specifically, the activation unit 60 When the rollers are nipped, the material is already at 100% (up to 200% of its original length). In the activation unit, the engagement depth "b" is (5 mm rib The overall height is 2mm.

[0086] Table 5 below shows the properties determined for the three samples of Example 5.

[0087] [Table 5-1]

[0088] [Table 5-2]

[0089] In addition to Examples 4 and 5 of the present invention, Example 6 is a comparison of Sample 4-1 of Example 4. The released elastic layers were spun and tested.

[0090] FIG. 8 shows the MD tensile ( This material shows very high stress-strain when subjected to a stress of 20 to 25 N / 50 mm. , specifically 500%, can be stretched in the MD before breaking.

[0091] FIG. 9 shows the sheet of the present invention of Sample 4-1 of Example 4, the decorative layer of Example 3, and 6 shows the MD tensile (stress-strain) superposition curves of the elastic layer of 6. Thus, the decorative layer maintains the elastic profile of the elastic layer until it reaches an elongation of over 300%. The sheet has high elongation, is elastic, and returns to its original state when relaxed.

[0092] The curves shown in Figures 8 and 9 were averaged over multiple measurements as the curve in Figure 7. It is a curve.

[0093] A further important parameter for elastic materials herein is the elastic modulus in accordance with ASTM D5459. Permanent deformation is the increase in length, expressed as a percentage of the original length. This allows the elastic material to be stretched as specified in the test procedure in ASTM D5459. The lower the % of permanent deformation, the better the elastic material will be. The elasticity increases.

[0094] Figure 10 shows the tensile (stress-strain) diagram and its corresponding graph showing the ASTM D5459 test. Schematic diagrams of the stress-strain cycles that follow and the subsequent increase and decrease curves are shown. This value is calculated by (AD / AE) x 100.

[0095] Another important parameter is the initial growth curve (A) expressed as %[A / (A+B)×100]. +B) relative to the area between the curves (A) and (B). Increase in hysteresis plot and the second cycle of ASTM D5459 test It is the area between the stress-strain curves of the deformation. It measures the percentage of energy dissipated by internal friction. As is usually seen in real-life materials, the plots during loading and unloading do not match. When the strain is high, a certain amount of energy is lost. The lower the %, the higher the elastic properties of the material.

[0096] FIG. 11 shows the first result of the ASTM D5459 test for Sample 5-1 of Example 5. 1 shows the stress-strain plots in the machine direction for the first and second cycles. The hysteresis curves are This material exhibits very favorable elastic properties in the flow direction. The permanent deformation after the first cycle was only 1.28%, and the difference between the increasing and decreasing curves in the second cycle The area of ​​is only 24.8%.

Claims

1. at least three layers of nonwoven material; one layer is one of the three layers and is an elastically stretchable nonwoven material having spunbond elastic fibers formed from a thermoplastic elastomeric polymer material; the other layer is a stretchable decorative layer having spunbonded crimped multicomponent fibers, which is two of the three layers; The elastically stretchable nonwoven material is sandwiched between the two facing layers on each side of the fabric, The three adjacent layers are bonded to each other by surface bonding points, which are achieved by embossing protrusions arranged on the surface of at least one calendar roll and applying ultrasonic vibrations to the embossing protrusions or by heating the embossing protrusions, and the surface bonding points are bonded to each other by applying ultrasonic vibrations to the embossing protrusions or by heating the embossing protrusions. 2 the number of junctions per fiber is greater than 20 but less than 100, and the total area of ​​the fiber surface occupied by the junctions is less than 18%; at least one of the components of the crimped multicomponent fiber is a propylene-α-olefin copolymer material; a further component of the crimped multicomponent fiber is a polypropylene homopolymer material; 1. An elastically stretchable nonwoven sheet, wherein the elongation at break of said sheet in the machine direction measured in accordance with WSP 100.4 is greater than 150%.

2. 2. The sheet of claim 1, wherein the permanent deformation in the machine direction measured according to ASTM D5459 is less than 15% after the first cycle.

3. 2. The sheet according to claim 1, wherein the propylene-α-olefin copolymer is a poly(propylene-ethylene) random copolymer.

4. 2. The sheet of claim 1, wherein the molecular weight distribution of the propylene-α-olefin copolymer is broader than the molecular weight distribution of the polypropylene homopolymer of the crimped multicomponent fibers.

5. The propylene-α-olefin copolymer M ｗ / M ｎ and M of the polypropylene homopolymer ｗ / M ｎ The sheet according to claim 4, characterized in that the difference between and is 2 to 10.

6. The propylene-α-olefin copolymer M ｗ / M ｎ and M of the polypropylene homopolymer ｗ / M ｎ The sheet according to claim 4, characterized in that the difference between and is 3 to 8.

7. The polypropylene homopolymer M ｗ / M ｎ is 2.5 to 7.5, and the M of the propylene-α-olefin copolymer ｗ / M ｎ The sheet according to claim 4, wherein is 4 to 10.

8. The sheet of claim 1 , wherein the crimped multicomponent fibers are bicomponent fibers.

9. 10. The sheet of claim 1, wherein the thermoplastic elastomeric polymer material forming the elastic fibers is a thermoplastic polyolefin elastomer.

10. The basis weight of each of the decorative layers is from 5 to 40 g / m 2 and / or the elastic layer has a basis weight of 10 to 140 g / m 2 2. The sheet according to claim 1, wherein:

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