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 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, e.g. in the back ears of open diapers, Elastically stretchable material for forming the waist belt portion of a diaper or pants-type diaper However, general nonwoven sheets cannot meet this requirement.

[0003] Conventional methods to address the problem of limited elastic elongation of nonwoven sheets include: An elastic layer may be provided between the layers of nonwoven material, so that the resulting laminate has 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 in the sheet, commonly called Lycra fiber. The problem with this method is localized elastic forces that can be uncomfortable for the wearer and can be easily distorted during manufacturing. The problem is that the strands are prone to breakage.

[0004] In addition, the sheet is made elastic by including elastic layers or strands. The elasticity remains within the maximum extensibility 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 of Approximately 50 to 80% in the machine direction (MD) and 70% in the cross 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 up to 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 demonstrate high elasticity. In order to achieve this, the materials used in elastic applications such as belts must be It is required to exhibit elastic elongation in the MD of the values ​​stated above.

[0005] Traditional approaches to addressing the limited stretchability of nonwoven materials include the use of elastic layers or The nonwoven sheet may be 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 disadvantage of pleating is that it requires a lot of material during production and the final product is thicker. This means that they are highly insulating and highly visible, 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 an elastically stretchable nonwoven sheet is disclosed in WO2020 This method is disclosed in US Pat. No. 6,399,363. The decorative layer is used, and the decorative layer is formed in the spunbonding process to form the spunbond elastic layer. The method includes depositing elastic fibers on the sheet. The sheet is then pre-stretched by a pair of corrugated rollers. The resulting product can be elastically stretched in CD to greater than 150% of its original dimension. Although it meets the industrial requirements, it is found 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 elasticity when passed through the manufacturing 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 EP3715517A1. This method uses a multi-beam spunbond line to produce a spunbonded fiber from 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 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. The elastically stretchable nonwoven material has spunbonded elastic fibers, and the other layer is spunbonded. A stretchable decorative layer having crimped multicomponent fibers, the adjacent layers being embossed. At least one of the components of the crimped multicomponent fiber is propylene- It is an α-olefin copolymer material.

[0011] Compared with the nonwoven sheet disclosed in EP3715517A1, both of the composite fibers of the decorative layer One component is made of polypropylene, and at least one of the composite fiber components is made of propylene. By using olefin-α-olefin copolymer (co-PP), the The overall elasticity of the sheet increases significantly 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 sheets according to the invention preferably exhibit favourable elastic behaviour, especially in the machine direction.

[0013] In one embodiment, the thermal conductivity measured according to ASTM D5459 after the first cycle 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 is 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, for example, eccentric. Other cross sections, such as sheath-core, may also be implemented.

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

[0017] The α-olefin which 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, the comonomer content is 2 wt.-% or more. 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 greater than 99.8 wt.-%, more preferably greater 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. The molecular weight distribution of the polypropylene homopolymer used in the other component of the composite fiber is preferably 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. On the other hand, M w / M n The difference between the M and the M is preferably 10 or less, and more preferably 8 or less. w / M n Appropriate The absolute value for polypropylene is, for example, 2.5 to 7.5, and for propylene-α-olefins, For olefin copolymers it can be from 4 to 10.

[0023] The components of the multicomponent fiber, co-PP or homo-PP, can be mixed with other polymers or It may be mixed with other additives such as slip agents, fillers or color masterbatches. 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. (TPE-o), preferably a propylene-α-olefin copolymer. Suitable thermoplastic polyolefin elastomers for use in the context of the present invention may include Such TPE-o materials are disclosed in EP 2 342 075 A1. In addition, in the sense of a mixture, other thermoplastic polyurethanes, such as thermoplastic polyurethanes (TPUs), are also used. Plastic elastomeric 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 Also, fillers, slip agents, color masterbatches, etc. may be added. 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 each made of the above-mentioned elastic material or composite material in addition to other fibers. It may comprise fibres, but preferably consists solely of the above mentioned elastomeric or bicomponent fibres.

[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 in covering 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 layer may be a spunbond nonwoven material and the other nonwoven layer may be 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 from 10 to 25 g / m 2 , more preferably 15 to 20 g / m 2 It is. The basis weight of the elastic layer is from 10 to 140 g / m 2 and preferably 20 to 120 g / m 2 , more preferably from 25 to 100 g / m 2 It is.

[0030] The sheet typically has a macroscopic pattern of bonds. 1 cm of the fiber surface 2 The number of junctions per unit area may be less than 100, preferably 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 fibers 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 easily stretched in the machine direction. This can be further activated by prestretching in the flow direction, as explained in more detail below. This is also fine.

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

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

[0034] The bonding in step (b) is most preferably embossed. embossing the sheet of at least one of the calender rolls, This is accomplished by embossing projections disposed on the surface. Embodiments include ultrasonic bonding. Ultrasonic vibrations are applied to the embossing projections. Another embodiment is to heat the embossing projections. Thermal bonding is used.

[0035] In a preferred variant, 1 cm of the fiber surface 2 The number of junctions per unit may be less than 100. The total area of ​​the fiber surface occupied by surface bonds is preferably less than 18% and more 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), most preferably at least one of the components of the crimped multicomponent fiber. is a propylene-α-olefin copolymer, and the fiber is used to form a woven fabric in step (a2). In a variation of this method, the preferred embodiment of the present invention A sheet according to a preferred embodiment is provided, and a sandwich structure of an elastic layer provided between two decorative layers is provided. Yes.

[0037] In one embodiment, the method further comprises pre-compressing the woven fabric of the decorative layer. After each corresponding step, there is 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-compressed pieces. The linear pressure applied is preferably between 3 and 5 N / mm. The roller temperature may be from 50 to 110° C. or higher, more preferably from 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 prestretching 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 interlocking 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 performed in-line or as a stand-alone process. This may also be done.

[0042] The extent of pre-stretching of the sheet in the machine direction in step (c) is such that the final sheet This can affect the range of elastic stretchability. Thus, 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 in comparison with the 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 fibers may be provided. Effect of the Invention

[0045] The nonwoven sheets according to the 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 MD.

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

[0047] [Figure 1] 1 is a schematic cross-sectional view of an elastically stretchable nonwoven sheet according to the present invention; [Diagram 2] An example of a machine configured to carry out the method of the present invention [Diagram 3] Schematic of a unit for activating sheets by stretching in the machine direction [Figure 4] Schematic diagram of the unit shown in Figure 3 in operation [Diagram 5] MD tensile (stress-strain) curves of separated spunbond decorative layers according to comparative example configurations [Figure 6] MD Tensile (Stress-Strain) Curves of Separate 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 ramp-up and ramp-down curves of stress-strain cycles illustrating ASTM D5459 testing. [Figure 11] 14. Tensile (stress-strain) plot in the machine direction for Sample 5-1 of Example 5 showing the hysteresis curve of the material. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[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 the first and second nonwoven decorative layers 120 .

[0049] A machine set up to manufacture 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 device is equipped with three printers 20, 30 and 40.

[0051] In each spunbond machine, molten thermoplastic polymer is forced 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 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 a thermoplastic elastomer onto the preformed woven fabric. The spunbonder 40 deposits another woven fabric of crimped composite fibers onto the elastic fiber fabric. Next to the presses 20 and 40, a pair of pre-compression rollers 21 and 41 pre-compress the woven fabric. Each has been established.

[0053] The pre-compressed woven fabric is then passed through a karren 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 61 and 62. 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 respective radial planes. The work 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 denoted by "c".

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

[0056] Even without activation, the polyimide has a relatively narrow molecular weight distribution in the crimped composite fiber. Polypropylene homopolymer and ethylene-propylene random copolymer having 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, in the embodiment. It was found that it was possible to realize a sheet that could be stretched up to 300%, which 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 is elastically stretchable by 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 treated with the materials specified below. I prepared it.

[0059] [Table 1]

[0060] The 511A polymer is manufactured by Savic 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 broad polymer weight distribution (M w / M n 6.8), MFR of 13g / 10min and T of 161°C m Polypropylene having It is a homopolymer.

[0062] RP248R polymer is a 30g / 10min MFR, intermediate Molecular weight distribution (M w / M n 5.2) and T of 148°C m Ethylene-propylene copolymer having The copolymer 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 of 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 ISO11357-3 It is understood that

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

[0067] JPEG2024102168000002.jpg47170

[0068] Fixed elution interval ΔV i In contrast, A i and M. i are the elution volumes V i Related 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 obtained from the chromatograph between the limits.

[0069] Infrared (IR) detector (PolymerChar, Valencia, Spain) High temperature GPC with Payne IR4 or IR5 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 1,2,4-tetracyclobenzene 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 particles 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 the 03 standard). 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 incubated at 160°C for 2.5 h. 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 test piece are shown.

[0073] [Table 2-1]

[0074] [Table 2-2]

[0075] In particular, none of the samples were activated with the mills shown in Figs. 3 and 4, and the 1 cm 2 Per 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 to 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 curves of multiple measurements that are then averaged, while FIG. 7 shows the curves of measurements that have already been averaged. Only the curves that were selected are shown.

[0077] As is apparent from the values ​​in Table 2 and the curves in Figures 5 to 7, the MD elongation of the decorative layer in Example 2 is 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 MWD difference between PP and Co-PP is larger than in Example 2. The cosmetic layer according to the preferred embodiment has a very high effect (an additional 80% improvement). MD elongation at break values ​​of nearly 200% despite not being pre-stretched (Example 2) And the value exceeding 250% (Example 3) generally indicates that the fiber arrangement is mainly in the machine direction. It is very specific to certain spunbond materials. Also, it is worth noting that the thickness of the decorative layer is To some extent, this is often related to the level of crimp, but the thickness of the decorative layer in Examples 2 and 3 The thickness of the decorative layer of the sheet according to the present invention is smaller than that of the sheet according to Comparative Example 1, despite the same basis weight. The effect of simple crimp level on the ability of the spunbond decorative layer to stretch in the machine direction is discussed. It is clear that there are other effects beyond the bell.

[0078] Next, as Example 4, an elastic strip sandwiched between two decorative layers constructed according to the present invention was used. Three sheets of the present invention having a spunbond layer (samples 4-1, 4-2 and 4-3) were prepared. The mill used for activating the material (unactivated sheet) was the same as that shown in FIG. 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 cosmetic 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 7050FL. 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 the fourth embodiment, in another fifth embodiment, 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 change in conversion speed in the line causes the activation unit 60 When the rollers are inserted into the nip, 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 of the

[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 examined.

[0090] FIG. 8 shows the MD tensile ( This material shows a very high stress-strain ratio 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 modulates the elastic profile of the elastic layer until it reaches an elongation of more than 300%. Not restrictive. The sheet has high elongation, is elastic, and returns to its original state when relaxed.

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

[0093] Further important parameters for elastic materials in this specification are: 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 % permanent deformation, the better the elastic material's ability to return to its original length. The elasticity becomes higher.

[0094] FIG. 10 shows the tensile (stress-strain) diagram and the corresponding The graph shows the stress-strain cycles followed by increasing and decreasing curves. This value is calculated by (AD / AE) x 100.

[0095] Another important parameter is the initial growth curve (A +B), the relative size of the area between the curves (A) to the total area below Increase in hysteresis plot during the second cycle of ASTM D5459 test and It is the area between the stress-strain curve 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 increased, a certain amount of energy is lost. The lower the %, the higher the elastic properties of the material.

[0096] FIG. 11 shows the first chromatogram of Sample 5-1 of Example 5 obtained according to the ASTM D5459 test. 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 machine direction. The permanent deformation after the test was only 1.28%, and the difference between the increase and decrease curves in the second cycle was The area of ​​the island 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 being two of the three layers, a stretchable decorative layer having spunbond crimped multicomponent fibers; 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 that are achieved by embossing the protrusions arranged on the surface of at least one calendar roll and applying ultrasonic vibration to the embossing protrusions or by heating the embossing protrusions, and the surface bonding points are bonded to each other by ... 2 the number of junctions per unit area is between 20 and 100, and the total area of ​​the fiber surface that is occupied by the areal 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 according to WSP 100.4, is greater than 150%.

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

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 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 is 3 to 8.

7. The polypropylene homopolymer M ｗ / M ｎ is 2.5 to 7.5, and the M 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. 2. 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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