WO2009073474A2

WO2009073474A2 - Elastic multilayer body and article using same

Info

Publication number: WO2009073474A2
Application number: PCT/US2008/084655
Authority: WO
Inventors: Hirofumi Hosokawa; Tadato Oritani; Naoyuki Toriumi
Original assignee: 3M Innovative Properties Company
Priority date: 2007-11-30
Filing date: 2008-11-25
Publication date: 2009-06-11
Also published as: RU2010121564A; WO2009073474A3; CN101883547A; JP2009132081A; JP5231001B2

Abstract

An elastic multilayer body is provided with excellent elastic characteristics, film durability, and productivity. The elastic multilayer body includes a nonwoven material and a layer that includes an elastomer composition. The elastomer composition includes (a) polyurethane elastomer, (b) styrene-isoprene-styrene copolymer, and (c) 0 mass% or more and less than 4 mass% of a tackifier based on the amount of the elastomer composition. The amount of the component (a) is between 90 and 99.9 mass% based on the total amount of components (a) and (b). The amount of the component (b) is between 0.1 and 10 mass% based on the total amount of components (a) and (b).

Description

ELASTIC MULTILAYER BODY AND ARTICLE USING SAME

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Japanese Application Number 2007-310948 filed on November 30, 2007, the entire content of which is hereby incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to an elastic multilayer body and to an article using the same (particularly to clothing such as underwear and hygienic articles such as disposable diapers).

BACKGROUND

Materials with elasticity are used in the region of the waist or the like (for example, in clothing such as underwear and in hygienic products such as disposable diapers) in order to improve the handling and fit of the article. For example, a so- called open type disposable diaper that is secured about an individual's waist with a mechanical fastener uses an elastic material in the attaching region (flaps) of the mechanical fastener. The elastic material has suitable elasticity such that the disposable diaper can be easily worn and the mechanical fastener can be easily closed. Furthermore, the elastic material has suitable softness and has minimal negative effects on the skin even when the diaper is worn for a long time.

Examples of these elastic materials include a thermoplastic polyurethane composition containing between 40 and 70 wt% of a thermoplastic polyurethane resin, between 10 and 25 wt% of an ethylene-propylene-diene copolymer, between 10 and 25 wt% of low density polyethylene resin, between 5 and 20 wt% of a styrene elastomer where the ratio of styrene modified by an unsaturated carboxylic acid or derivative thereof is 30 wt% or less, and between 0 and 20 wt% of unmodified styrene elastomer (Japanese Unexamined Patent Application H7-138470), and a thermoplastic polyurethane resin composition containing between 40 and 60 wt% of (a) thermoplastic polyurethane resin, between 10 and 30 wt% of (b) ethylene-propylene- diene copolymer, between 10 and 30 wt% of (c) low density polyethylene resin, between 10 and 30 wt% of (d) styrene elastomer where the ratio of styrene modified by unsaturated carboxylic acid or derivative thereof is 30 wt% or less, and between 2 and 10 wt% of (e) unmodified styrene elastomer (Japanese Unexamined Patent Application H8-41317).

Furthermore, an extrusion bonded nonwoven elastic film multilayer body containing an elastomer film directly bonded to at least one nonwoven web layer that is essentially continuous across at least a part of a multilayer body that forms an elastic part is known where the extrusion bonded nonwoven elastic film multilayer body has a yield point elongation rate of at least 250%, tension (Si) at an elongation of 100% that is larger than 300 N/cm², and a useful elastic range that is larger than 100% elongation (Japanese Patent Publication 2003-520705).

Furthermore, an elastic multilayer body that includes a core material where a nonwoven material is attached on at least one side is known, wherein the core material is made from a styrene elastomer with styrene content between 15 and 45%, the nonwoven material is continuously attached to the core material, and when the multilayer member is stretched to 100%, breaking and peeling from the core member will not occur in a range proximal to this elongation, and the tension of the nonwoven material at an elongation of 50% is 3 N/25 mm or less in the CD direction, and after the elastic member has been elongated to 100% and then returned to the original condition by relaxing the tension (first elongation) and then elongated again to 100% (second elongation), the ratio between the tension (A) when elongated to 50% during the first elongation to the tension (B) when elongated to 50% during the second elongation (A/B) is 3.0 or less (Japanese Unexamined Patent Application 2007- 230180).

SUMMARY

In one embodiment, the present invention provides an elastic multilayer body comprising a nonwoven material and a layer including an elastomer composition, the elastomer composition comprising (a) polyurethane elastomer, (b) styrene-isoprene- styrene copolymer, and (c) 0 mass% or more and less than 4 mass% of a tackifier based on the amount of elastomer composition. The amount of the component (a) is between 90 and 99.9 mass% based on the total amount of the components (a) and (b), and the amount of the component (b) is between 0.1 and 10 mass% based on the total amount of the components (a) and (b).

In another embodiment, the present invention provides an article that includes the elastic multilayer body. In a further embodiment, the elastic multilayer body exhibits excellent elastic properties, durability, and productivity.

Other features and aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a cross-sectional view of an elastic multilayer body according to some embodiments of the present invention.

Fig. 2 is a perspective view of a disposable diaper with flaps made from an elastic multilayer body according to some embodiments of the present invention. Fig. 3 is a schematic diagram showing a manufacturing process of an elastic multilayer body according to some embodiments of the present invention.

DETAILED DESCRIPTION

Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways.

The present invention provides an elastic multilayer body comprising a nonwoven material and a layer containing (a) polyurethane elastomer, (b) styrene- isoprene-styrene copolymer, and (c) a tackifϊer (optional component).

First, the polyurethane elastomer (component (a)) that is included in the elastomer composition will be described. The polyurethane elastomer has a urethane bond in the molecule, and can be obtained by a polyaddition reaction between a polyol component containing long chain polyols and short chain polyols, and an isocyanate such as a diisocyanate. The polyol that is used can be a polyester type, adipate type, polyether type, or polycaprolactone type polyol.

Examples of long chain polyols include polyether diols (such as poly(oxytetramethylene) glycol and poly(oxypropylene) glycol) and polyester diols (such as poly(ethylene adipate) glycol, poly(l,4-butylene adipate) glycol, poly(l,6- hexylene adipate) glycol and poly(hexanediol-l,6-carbonate) glycol) and the like. Examples of short chain polyols include ethylene glycol, 1,3-propylene glycol, bisphenol A, 1 ,4-butanediol, and 1 ,4-hexanediol and the like.

Examples of the diisocyanate include 4,4'-diphenylmethane diisocyanate, toluene diisocyanate, and hexamethylene diisocyanate and the like.

In one aspect, the Shore A hardness (JIS A hardness) of the polyurethane elastomer can be between 60 and 95. If the Shore A hardness (JIS A hardness) of the polyurethane elastomer is between 60 and 95, the film stability can be increased when the elastomer composition is melted and a film is formed, and therefore a film with good elastic flexibility can be achieved.

In another aspect, two or more types of polyurethane elastomers can be used in combination.

For example, commercially available examples of the polyurethane elastomers which can be used include PANDEX (registered trademark) T- 1575 (product of DIC Bayer Polymer Ltd.), Elastollan (registered trademark) ET-680 (product of BASF Japan Ltd.), and Miractran (registered trademark) E675 (product of Nippon Polyurethane Industry Co. Ltd.), and the like.

Next, the styrene-isoprene-styrene copolymer (component (b)) that is included in the elastomer composition will be described. The styrene-isoprene-styrene copolymer (hereinafter also referred to as "SIS copolymer") preferably contains between 15 and 45% styrene from the perspective of film strength and elastic flexibility.

The melted flowrate of the SIS copolymer (200⁰C, 5.0 kg) is preferably higher, from the viewpoint of fluidity (workability) and the film stability when the elastomer composition is made into a layer, and in one aspect, the melted flowrate can be in a range between 10 and 45. Furthermore, in another aspect, the lower limit of the melted flow rate of the SIS copolymer can be 20, and the upper limit can be 40. The SIS copolymer can be either a non-modified type or a modified type. A modified SIS copolymer can be obtained by the addition reaction (for example graft reaction) of an unsaturated carboxylic acid or derivative thereof onto a SIS copolymer. Specific examples include maleic acid, fumaric acid, itaconic acid, acrylic acid, crotonic acid, endo-bicyclo[2,2,l]-5-heptene-2,3-dicarboxylic acid, and cis-4-cyclohexene-l,2-dicarboxylic acid, as well as anhydrides and imido compounds thereof.

In another aspect, a SIS copolymer with three or more branched chains can also be used as the SIS copolymer. Furthermore, in another aspect, a combination of two or more types of SIS copolymer can be used.

For example, Kraton Dl 114P, Kraton Dl 117P (products of Kraton Polymer Japan), and Vector 4111 (product of Dexco Polymer LP) can be used as the SIS copolymer. The elastomer composition may also contain a tackifier (component (c)) as an optional component in addition to component (a) and component (b).

The tackifier does not break the polyurethane elastomer structure and is preferably a material that has good compatibility with the SIS copolymer. The material that is used can be rosin-based, terpene-based, or petroleum-based, or the like. Two or more types of tackifiers can also be used in combination.

In another aspect, the softening point of the tackifier is between 40 and 160⁰C, or within a range between 70 and 160⁰C.

As commercially available examples, Pine Crystal (registered trademark) (Arakawa Chemical Industries Ltd.) is a rosin-based tackifier; YS Polystar (registered trademark) (Yasuhara Chemical) is a terpene-based tackifier; and Wingtack Plus (registered trademark) (Product of CRAY VALLEY) and Alcon (registered trademark) (Arakawa Chemical Industries Ltd.) are petroleum-based tackifiers.

The elastomer composition can also contain various other additives (such as antioxidants, weathering agents, UV absorbers, colorants, inorganic fillers, and oils and the like). However, in another aspect, the elastomer composition contains essentially no low density polyethylene and no ethylene-propylene-diene copolymer. Next, the formulation of the elastomer composition will be described. First, the amount of tackifier which is an optional component is 0 mass% or higher and less than 4 mass% based on the total amount of the elastomer composition. If the aforementioned amount of tackifier is added to the elastomer composition, the productivity when making the layer that includes an elastomer composition and the yield strength of the layer that is obtained will be improved. Furthermore, in another aspect, the amount of tackifier can be between 0.2 mass% and 0.8 mass%.

Furthermore, the amount of polyurethane elastomer (component (a)) in the elastomer composition is in a range between 90 and 99.9 mass% with regard to the total amount of component (a) and component (b), and the amount of SIS copolymer (component (b)) is in a range between 0.1 and 10 mass% with regard to the total amount of component (a) and component (b). If component (a) and component (b) are within the aforementioned ranges, the productivity when forming a layer that includes the elastomer composition and the yield strength of the layer obtained will be improved. In another aspect, the amount of component (a) is in a range between 98 and 99.5 mass%, with regard to the total amount of component (a) and component (b), and the amount of SIS copolymer (component (b)) can be in a range between 0.5 and 2 mass% with regard to the total amount of component (a) and component (b).

Furthermore, in another aspect, the total amount of component (a) and component (b) can be 96 mass% or higher with regard to the amount of elastomer composition, from the perspective of the yield strength of a layer that includes the elastomer composition.

Next, the nonwoven material that is included in the elastic multilayer body will be described. The fiber material that composes the nonwoven material is not particularly restricted, and can be made from various types of conventionally known fiber materials. In another aspect, the fiber material is preferably a blend of polyester fibers and polyolefm fibers, from the perspective of the elasticity and strength of the elastic multilayer body. The fiber blend ratio is not particularly restricted, but a blend that contains primarily polyester fibers which are blended with polyolefm fibers is preferable from the perspective of elasticity and strength. In another aspect, a blended fiber can be used where polyester fibers and polyolefm fibers are blended at a weight ratio between approximately 95:5 and approximately 5:95. Furthermore, the blending ratio of polyester fibers and polyolefm fibers can be in a mass ratio range between approximately 90:10 and approximately 15:85 in order to achieve a high balance between maintaining elastic strength after elongation of the elastic multilayer body and preventing delamination.

The manufacturing method for the nonwoven material is not restricted. The nonwoven material can be manufactured from the aforementioned materials using a commonly known manufacturing method. The spunbond method or a non-spun method or the like are preferable from the perspective of providing favorable extensibility to the elastic multilayer body. The non-spun method can cause the nonwoven material obtained to have a favorable feel on the skin. Continuing, the construction of the elastic multilayer body will be described.

The elastic multilayer body comprises a nonwoven material and a layer that contains the aforementioned elastomer composition. Furthermore, in addition to the nonwoven material and the layer containing the elastomer composition, the elastic multilayer body can also contain a urethane powder or a fibrous construction such as a weave. For example, the elastic multilayer body may have a construction with a nonwoven material or the like on one side of a layer containing an elastomer composition, or may have a construction with a nonwoven material on both sides of the layer containing an elastomer composition. The layer containing an elastomer composition can be elastically elongated, in a condition where a nonwoven material is formed on one surface or where the layer is sandwiched between nonwoven materials.

The thickness of the layer that contains the elastomer composition can be between approximately 5 and 65 μm, and either a single layer construction or a multilayer construction is acceptable. For the case of a multilayer construction, each of the layers can be constructed from a different elastomer composition. The thickness of the nonwoven material can be between approximately 30 μm and 1 mm. Furthermore, the nonwoven material can generally have a weight per unit area between approximately 20 and 50 gsm. Note, the thickness of the entire elastic multilayer body can vary across a wide range depending on the application, but is generally within a range between approximately 50 μm and 2 mm. Herein, an example of a case where a nonwoven material is formed on both sides of a layer that contains an elastomer composition will be described. As is schematically shown in Fig. 1, the elastic multilayer body 10 has a construction where a first nonwoven material 1 and a second nonwoven material 2 are provided on both surfaces of a layer 3 containing an elastomer composition. The first nonwoven material 1 and the second nonwoven material 2 can be continuously bonded to the entire surface of the layer 3 containing an elastomer composition. The elastic multilayer body 10 is normally provided in the form of a sheet with a flat construction. The first and second nonwoven materials can be made from the same nonwoven material, or can be made from different nonwoven materials. Similarly, the first and second nonwoven materials can have the same or different thickness and weight per unit area. The elastic multilayer body can be constructed to have the same elastic properties throughout the entire body, or can be constructed to have two or more regions with different elastic properties. Furthermore, the elastic multilayer body can have a construction that combines an elastic region which has elasticity and a non- elastic region which does not have elasticity. By controlling the region of the elasticity in one elastic multilayer body, the properties of the elastic multilayer body can be changed, and the handling properties can be improved. The method of manufacturing an elastic multilayer body with this type of construction will be described later.

As shown for example in Fig. 2, if the center region of an elastic multilayer body 10 is an elastic region A, and both side parts are non-elastic regions B, attaching the elastic multilayer body 10 to a disposable diaper 100 and attaching a mechanical fastener 120 can easily be performed, and therefore the properties and the feel during use of the elastic multilayer body 10 can be favorably maintained.

In another aspect, the elastic multilayer body has a layer containing an elastomer composition with a breaking elongation of 115% or higher.

The elastic multilayer body can be constructed by separately constructing a layer containing an elastomer composition and the nonwoven materials, and then performing a laminating process. Furthermore, the elastic multilayer body can also be constructed by integrally forming the layer containing an elastomer composition and the nonwoven materials using a simultaneous melting and extruding lamination method. Either a multilayer body with a two layer construction consisting of a layer containing an elastomer composition and a nonwoven material or a multilayer body with a three layer construction consisting of a first nonwoven material, a layer containing an elastomer composition, and a second nonwoven material can be manufactured by the simultaneous melting and extruding lamination method.

The simultaneous melting and extruding lamination method has various processes, but for example, the elastic multilayer body can be manufactured by a serial process as shown in Fig. 3. The first nonwoven material 1 is unrolled from a supply roll 21, and is fed between a pair of lamination rollers 24, 25 as shown by the arrow. On the other hand, the second nonwoven material 2 is unrolled from a supply roller 22, and is fed between a cooling roller 25 and a nip roller 24 as shown by the arrow. The cooling roller 25 and the nip roller 24 can be made from a calendar roller and a rubber roller which both have essentially smooth surfaces. The layer 3 containing an elastomer composition is fed in the form of melted flow from a die (normally a T-die) 23 that is connected to an extruder (not shown in the drawings), and is fed between the first nonwoven material 1 and the second nonwoven material 2, where the layer is cooled and hardened. Note, if the layer containing an elastomer composition has a multilayer construction, the layer 3 containing an elastomer composition can be fed in the form of multilayered melted flow from a die 23 using two or more extruders.

The first nonwoven material 1 , the layer 3 containing an elastomer composition, and the second nonwoven material 2 are laminated and integrated by the cooling roller 25 and the nip roller 24, as shown in the drawings. The sheet like multilayer body obtained receives a tensile force from a tension roller 26 and is fed in the direction of the arrow along the outer circumference of the cooling roller 25. The elastic multilayer body 10 manufactured in this manner is made to change directions at the tension roller 26, and is then fed in the direction shown by the arrow and wound on a take-up reel (not shown in the drawings).

The elastic multilayer body obtained in this manner can be manufactured by simultaneously performing an elastomer film forming process and a process of laminating the elastomer film with a first nonwoven material and a second nonwoven material, and therefore has excellent cost performance.

Note, as described above, if the elastic multilayer body is manufactured using a simultaneous melting and extruding lamination method, the construction may have a region where the layer containing an elastomer composition and the nonwoven materials are strongly bonded, and a region where the layer containing an elastomer composition and the nonwoven materials are weakly bonded, in order for the elastic multilayer body to have an elastic region with elasticity and a non-elastic region without elasticity. The means can be a method where the melted flow (melted polymer) of the elastomer composition that is extruded from a T-die by melting and extruding is interpositioned between the first and second nonwoven materials, and then pressed on one or both sides by a nip roller having a specific protruding pattern to cool and hardened the polymer. The shape of the protruding pattern can be an elliptical cylinder shape, a dot shape, a diamond shape, or a text character shape. In this case, the region that is nipped by the protruding pattern will have a strong bond between the nonwoven material and the elastomer film. If the strongly bonded regions are densely formed, a non-elastic region will be created, but on the other hand if the strongly bonded regions are sparsely formed, an elastic region will be created. Furthermore, heat needling of the elastic multilayer body obtained can be performed in order to provide permeability to moisture, and permeability to moisture can also be provided by appropriately perforating the elastic multilayer body.

The elastic multilayer body and article of the present invention can have a variety of advantageous forms. The elastic multilayer body described in this specification can be used with clothing such as underwear, a hygienic article such as a disposable diaper (for example, the attached flaps of the mechanical fastener of a disposable diaper), an elastic supporter, or as an ear support for a mask. Hereinafter, an example where the elastic multilayer body is used as a flap for attaching a mechanical fastener to a disposable diaper will be described. Fig. 2 is a perspective view of an open type disposable diaper 100 where the elastic multilayer body 10 of the present invention forms flaps 110. The disposable diaper 100 is made from a rectangular laminate 122 including a liquid impermeable polymer film 124 on the outside, and a liquid absorbent layer 126 on the inside. Although not shown in the drawings, a liquid absorbent polymer is stored inside the laminate 122. Furthermore, a loop material 132 is attached to the outside of the polymer film 124 in order to engage with a hook material 125 of a mechanical fastener 120 to secure the diaper to the wearer when the diaper is worn. Herein, the hook material 125 comprises a collection of small protrusions which have a cross- section in the shape of a mushroom, and the loop material 132 comprises a woven material or a nonwoven material with a surface construction that can become entangled with the hook material 125.

For the case of the disposable diaper 100 shown in Fig. 2, an elastic multilayer body 10 is used for the flaps 110, and therefore applying the diaper is quick and easy, and after the diaper is applied, the elastic multilayer body 10 is soft and has a good feel on the skin, and therefore the diaper can be comfortably worn by infants, the elderly, and the ailing without causing problems such as skin irritation. Furthermore, with the disposable diaper 100, the hook material 125 may be repeatedly removed from the loop material 132 and then reattached to the loop material 132, but the elastic multilayer body 10 has minimal loss of elastic force when repetitively stretched, and therefore peeling of the nonwoven materials and cracking of the layer that contains an elastic composition will not occur.

Exemplary embodiments of the present invention are provided in the following examples. The following examples are presented to illustrate the present invention and methods for applying the present invention and to assist one of ordinary skill in making and using the same. The examples are not intended in any way to otherwise limit the scope of the invention.

EXAMPLES Manufacturing a Film from an Elastomer Composition

Embodiments El through Ell, Comparative Examples Cl through C5. A film was manufactured from an elastomer composition using a film manufacturing device (manufactured by Tanabe Plastic Machinery Co. Ltd., model number: VS30) consisting of a T-die single screw melt extruder and a chill roller. Polyurethane elastomer (TPU), styrene-isoprene-styrene copolymer (SIS), and a tackifier (TF) were dry blended using the amounts shown in Table 1 and Table 2 to make an elastomer composition which was then added to a T-die single screw extruder that had been heated to 200⁰C. PANDEX (registered trademark) T-575X (A harness: 75, pellet form) manufactured by DIC Bayer Polymer Ltd. was used as the polyurethane elastomer, Kraton D-1117 (pellet form a) manufactured by Kraton Polymer Japan was used as the styrene-isoprene-styrene copolymer, and a petroleum-based tackifier (product name: Alcon (registered trademark) P 125, manufactured by Arakawa Chemical Industries Co., Ltd., softening point: 125°C) was used as the tackifϊer. Next, using an extrusion rotational speed of 20 rpm and a take-up reel speed of 3 mpm for the T-die single screw extruder, a film like melted body was extruded from the T-die of the single screw extruder and fed between a nip roller and a chill roller controlled to 20⁰C, and then cooled and hardened to form a film with a thickness of

30 μm.

Motor Torque Value of T-die Single Screw Melting Extruder. The motor torque value of the T-die single screw extruder during extrusion was measured using a current meter attached to the aforementioned extruder. The results are shown in Table 1 and Table 2. For the case where a T-die single screw extruder is used with this embodiment, it was determined that at a motor torque value of 12.5 A or less, a sufficient level of extruding can be obtained and a commercial scale production line speed can be achieved, and therefore productivity is excellent.

Evaluation of Film Properties. The breaking strength (breaking elongation) and the tension characteristics ("fit" for the case of an elastic multilayer body) of a film were evaluated by the following methods for film obtained according to the aforementioned embodiments and comparative examples. The results are shown in Table 1 and Table 2.

Breaking Strength. A test sample with a 50 mm width in the longitudinal direction of the film (MD) and a 150 mm length in the lateral direction of the film (CD) was cut from the film obtained. Next, using a feather knife, 10 mm cuts in the MD direction were made in the center region of the test sample in the CD direction. The test sample was then secured in a tensile tester (manufactured by Shimadzu Corporation, Model number: AGIS) with the tensile direction in the CD direction of the film, such that the distance between chucks was 50 mm in a state of no tension.

After securing the test sample, the test sample was stretched to breaking at a speed of 100 mm/minute, and the elongation (breaking elongation) (%) of the test sample at the time of breaking was measured.

Tension Characteristics (100% Elongation Cycle in CD Direction) . A test sample with a 25 mm width in the longitudinal direction of the film (MD) and a 100 mm length in the lateral direction of the film (CD) was cut from the film obtained. The test sample was secured in a tensile tester (manufactured by Shimadzu Corporation, model number: AGIS) with the chuck distance set to 25 mm, with the CD direction of the test sample in the tensile direction. The test sample was elongated to 100% at a speed of 300 mm/minute, and then returned to the original chuck distance at a speed of 300 mm/minute. Upon returning to the original chuck distance from the 100% elongation condition, the strength (N) of the test sample was measured when the test sample was elongated to 50% (return tension 50%).

TABLE 1

Mass% refers to the value based on the amount of elastomer. 2Mass% refers to the value based on the total amount of TPU and SIS. TABLE 2

Mass% refers to the value based on the amount of elastomer. 2Mass% refers to the value based on the total amount of TPU and SIS.

Manufacturing the Elastic Multilayer Body

Embodiments El 2 through El 5, Comparative Example C6. An elastic multilayer body comprising a layer containing an elastomer composition and a nonwoven material was manufactured from an elastic non-spun nonwoven material (product name: ST-30, product of Daiwabo Polytec Co. Ltd.) (weight per unit area: 30 gsm) made of a blend of polyester fibers and polypropylene fibers (blending ratio - polyester fibers: polypropylene fibers = 90:10) by the simultaneous melting and extruding lamination process shown in Fig. 3 under the processing conditions shown in Table 3 (extrusion temperature (⁰C) and nip pressure (MPa)). TPU, SIS, and TF were fed into a single screw extruder at the formulation ratios shown in Table 3 (similar to Embodiments E3, E5, E8, and E9 as well as Comparative Example C3), and after dry blending, a melted body in the form of the film was extruded from the T- die. Next, the film-like melted body extruded from the T-die was fed between the first nonwoven material and the second nonwoven material (sandwiched between the first and second nonwoven materials). This multilayer body comprising the first nonwoven material/layer containing elastomer composition/second nonwoven material was inserted into the nip between a chill roller and a nip roller (with a dot shaped protruding pattern) in order to integrate the layers, and then cooled and hardened in order to harden the melted elastomer composition between the nonwoven materials, thus obtaining a three layered elastic multilayer body comprising a first nonwoven material, a layer containing an elastomer composition, and a second nonwoven material. With the elastic multilayer body obtained, the nonwoven material and the layer containing an elastomer composition were strongly bonded in the region that was nipped by the protruding pattern section of the nip roller, and were weakly bonded in the other regions. Furthermore, the thickness (μm) of the elastic multilayer body obtained is shown in Table 3.

Physical Evaluation of the Elastic Multilayer Body. The tension of the elastic multilayer body (CD direction, 100% elongation cycle), delamination, and elongation retention force were measured by the following methods for the elastic multilayer bodies obtained according to Embodiments E12 through E 15 and Comparative Example C6. The results are shown in Table 3.

Tension (100% Elongation Cycle in CD Direction). A test sample with a 50 mm width in the longitudinal direction (MD) and a 25 mm length in the lateral direction (CD) was cut from the elastic multilayer body obtained. The test sample was then secured in a tensile tester (manufactured by Shimadzu Corporation, Model number: AGIS) with the tensile direction in the CD direction of the test sample, such that the distance between chucks was 25 mm without tension. The test sample was elongated to 100% at a speed of 300 mm/minute, and then returned to the original chuck distance at a speed of 300 mm/minute (recovery). During elongation of the test sample, the strength A (50% of initial tension, during elongation) (N) of the test sample was measured when the elongation of the test sample was 50%. Furthermore, the elongation cycle was repeated again, and after the test sample had recovered from elongation, and during elongation of the test sample, the strength B (50% of 2nd tension, during elongation) (N) of the test sample was measured when the elongation of the test sample was at 50%. A value for A/B that is near 1 means less hysteresis loss when the elastic multilayer body is repeatedly used, and is considered to be a favorable elastic property.

Delamination. A test sample where the aforementioned elongation test had been repeated twice was observed for the presence of delamination that would allow a needle with a 1 mm diameter to pass through from the section of the layer containing an elastomer composition. Furthermore, the delamination was similarly observed for a test sample that had undergone 10 elongation cycles. Herein, an evaluation of O was made if delamination was not observed, an evaluation of Δ was made if the lamination was observed, but a 1 mm diameter needle could not pass through, and an evaluation of x was made if delamination was observed and a 1 mm diameter needle could pass through.

Elongation Retention Force. A test sample with a 50 mm width in the longitudinal direction (MD) and a 100 mm length in the lateral direction (CD) was prepared from the elastic multilayer body obtained. Through holes with a diameter of approximately 0.8 mm were opened across the entire surface of the test sample using a hot needle with a pitch of 8 mm in the lateral direction and 8 mm in the longitudinal direction. Next, the test sample with through holes was secured on one end in the MD direction, and elongated in the CD direction by applying a 500 g weight across a 50 mm length on the other end (entire length of the test sample in the MD direction). The test sample was left in this condition for 1 hour in a 40⁰C environment, and the sample was visually inspected for enlarging of the holes that had been opened in the test sample and for the presence of tearing from the hole. The elongation retention force was evaluated by making an evaluation of O if no enlarging of the hole was observed, an evaluation of Δ if enlarging (or tearing) of the holes was observed, but the size of the holes after enlarging was 5 mm or less, and an evaluation of x if enlarging (or tearing) of the holes was observed, and the size of the holes after enlarging was greater than 5 mm. TABLE 3

The embodiments described above and illustrated in the figures are presented by way of example only and are not intended as a limitation upon the concepts and principles of the present invention. As such, it will be appreciated by one having ordinary skill in the art that various changes in the elements and their configuration and arrangement are possible without departing from the spirit and scope of the present invention. Various features and advantages of the present invention are set forth in the following claims.

Claims

CLAIMSWhat is claimed is:

1. An elastic multilayer body comprising a nonwoven material and a layer that includes an elastomer composition, wherein the elastomer composition comprises (a) polyurethane elastomer, (b) styrene- isoprene-styrene copolymer, and (c) 0 mass% or more and less than 4 mass% of a tackifier based on the amount of the elastomer composition; and the amount of the component (a) is between 90 and 99.9 mass% based on the total amount of the components (a) and (b), and the amount of the component (b) is between 0.1 and 10 mass% based on the total amount of the components (a) and (b).

2. The elastic multilayer body according to claim 1, wherein the elastomer composition contains essentially no low density polyethylene and no ethylene-propylene-diene copolymer.

3. The elastic multilayer body according to claim 1 or 2, wherein the total amount of the components (a) and (b) is 96 mass% or higher based on the amount of the elastomer composition.

4. The elastic multilayer body according to any one of claims 1 through 3, wherein the layer containing the elastomer composition has a breaking elongation of 115% or higher.

5. An article comprising the elastic multilayer body according to any one of claims 1 through 4.