Polydimensional stretchable laminates

Abstract

To provide methods of making laminates which are recoverably stretchable in multiple directions and are suitable for outer covers of absorbent articles.SOLUTION: A method of making a laminate comprises the steps of: longitudinally stretching an elastomeric film comprising an olefinic block copolymer, a styrenic block copolymer or a combination thereof; and laminating the elastomeric film to a spunlace nonwoven substrate which is primarily transversely stretchable while the elastomeric film is stretched in the longitudinal direction.SELECTED DRAWING: None

Description

Content of disclosure

[0001] Related Applications This application claims the benefit of priority to U.S. Provisional Patent Application No. 62 / 691,738, filed June 29, 2018.

[0002] FIELD OF THEINVENTION The present invention relates to laminates that are recoverably stretchable in multiple directions and are suitable for use in absorbent articles.

[0003] BACKGROUND OF THEINVENTION The outer cover of an absorbent article typically comprises a laminate including a film and a nonwoven. The absorbent article may not conform adequately to the wearer's body in response to body movements (e.g., sitting, standing, walking). This conformity problem is exacerbated by the fact that one type of absorbent article must typically fit many wearers of different body shapes and sizes.

[0004] Thus, a need exists for an outer cover that exhibits low force multi-dimensional stretch and recovery, thereby providing a tailored, discrete fit.

[0005] Summary of the Invention The present invention meets the above-mentioned needs by providing an elastomeric laminate comprising an elastomeric film and a suitable nonwoven fabric. The film is primarily stretchable in the machine direction. Thus, it is expected that the film will limit the extensibility and recovery of the laminate in other directions. However, surprisingly, when laminated to a suitable nonwoven fabric that is stretchable in the cross direction, the resulting laminate is recoverably stretchable in substantially all directions. Thus, the laminate is particularly suitable for use in absorbent articles where separate fit and conformity are desired.

[0006] The present invention further describes a method for making an elastomeric laminate in which a film is joined to a nonwoven fabric while being stretched in the machine direction. [Brief description of the drawings]

[0007] [Figure 1] An example of a laminate exhibiting biaxial orientation is shown. [Diagram 2] An example of a laminate exhibiting multi-dimensional or multiaxial orientation is shown. [Diagram 3] 1 is a graph showing the cross direction (CD) load at 5% strain in N / cm (x-axis) as a function of the machine direction (MD) load at 5% strain in N / cm (y-axis) for a laminate of the invention (a spunlace nonwoven) and comparative laminates (a spunbond ("SB") and a spunbond-meltblown-spunbond ("SMS") nonwoven). [Figure 4] 4 shows the percentage of CD elongation at peak strain (x-axis) as a function of the percentage of MD elongation at peak strain (y-axis) for a laminate of the invention (spunlace nonwoven) and comparative laminates (SB and SMS nonwovens). [Diagram 5] The CD elongation in millimeters at 1000 g (x-axis) is compared as a function of the MD elongation in millimeters at 1000 g (y-axis) for a laminate of the invention (spunlace nonwoven) and comparative laminates (SB and SMS nonwovens). [Figure 6] 1 shows the percentage of applied stretch (x-axis) as a function of MD elongation in millimeters at 1000 g (y-axis) for a laminate of the invention (spunlaced nonwoven) and comparative laminates (SB and SMS nonwovens). [Figure 7] 1 shows the CD / MD elongation ratio (ER) at 1000 g load for a laminate of the invention (spunlace nonwoven) and comparative laminates (SB and SMS nonwoven). [Figure 8] 1 shows the CD / MD elongation ratio at peak (EAPR) at peak strain for a laminate of the invention (spunlace nonwoven) and comparative laminates (SB and SMS nonwovens).

[0008] Detailed Description of the Invention "Biaxially extensible" or variations thereof means that the laminate is recoverably stretchable in two directions in the xy plane, e.g., in the MD and CD, to at least twice its original length, as shown in FIG.

[0009] By "multidimensionally extensible", "multiaxially extensible" or variations thereof it is meant that the laminate is recoverably extensible in at least three directions in the xy plane to at least two times its original length, for example as shown in FIG. 2.

[0010] By "uniformly multidimensionally extensible" it is meant that the laminate is recoverably stretchable after being stretched in any direction to at least twice its original length.

[0011] "Recoverably stretchable", "recoverable" or variations thereof mean that when the laminate is stretched at least twice (200%) its original length, the laminate returns to no more than about 1.2 times its original length, measured in the direction of the applied stretching force.

[0012] "Predominantly extensible" or variations thereof means that a film or nonwoven substrate has a substantially greater degree of extensibility in one particular direction (eg, CD or MD) than in other directions.

[0013] "Gsm" means grams per square meter and is a measure of basis weight, an industry standard term for quantifying the thickness or unit mass of a film or laminate product.

[0014] "Preactivated", "activated", or variations thereof, refers to a process in which an elastomeric film or material is rendered more easily stretchable prior to lamination, for example, by stretching the film and then relaxing it. The film can be preactivated in the CD and / or MD.

[0015] The films of the present invention are elastomeric films, examples of which are disclosed in U.S. patent application Ser. No. 15 / 901,240, filed Feb. 21, 2018, which is incorporated herein by reference in its entirety.

[0016] The film may be a multi-layer or mono-layer film and may comprise one or more styrenic block copolymers (SBC) and / or olefinic block copolymers (OBC). Suitable SBCs include, but are not limited to, styrene-butadiene-styrene (SBS), styrene-isoprene-styrene (SIS), styrene-isoprene-butylene-styrene (SIBS), styrene-ethylene-butylene-styrene (SEBS), styrene-ethylene-propylene (SEP), styrene-ethylene-propylene-styrene (SEPS), or styrene-ethylene-ethylene-propylene-styrene (SEEPS) block copolymer elastomers, as well as copolymers and mixtures of any of the above. While any SBC can be used, particularly useful SBCs in the films of the present invention are non-hydrogenated SBCs, including, but not limited to, SBS, SIS, and SIBS. Non-limiting examples of SBCs suitable for use in the present invention include those available from Dexco Polymers of Plaquemine, Louisiana, such as VECTOR 4111A and 7620.

[0017] Olefin-based block copolymers (OBC) suitable for use in one or more layers include polypropylene-based (also called "propylene-rich") olefin-based block copolymers such as those sold under the trade name INFUSE, non-limiting examples of which include INFUSE 9507, 9100, 9507, 9107 and 5230 sold by The Dow Chemical Company, Midland, Michigan, and VISTAMAXX and IMPACT, e.g., VISTAMAXX 6102, available from ExxonMobil Chemical Company, Houston, Texas.

[0018] The total amount of SBC and / or OBC in the film or individual layers can be at least about 50%, about 50% to about 100%, about 60% to about 99%, about 50% to about 95%, about 55% to about 95%, about 60% to about 95%, about 65% to about 95%, about 70% to about 95%, about 75% to about 95%, about 80% to about 95%, about 70% to about 90%, or alternatively about 80% to about 90%.

[0019] Each of the outer layers (A layers, or skin layers) can further comprise polypropylene in an amount of at least 10%, at least 15%, at least 20%, at least 25%, about 1% to about 90%, about 1% to about 85%, about 1% to about 80%, or about 1% to about 75%. In one embodiment, the polypropylene is present in an amount of at least 20%, and in another embodiment, about 20% to about 85%.

[0020] The film has a basis weight that is economical and suitable for use in absorbent articles. The film is primarily stretchable in one direction, typically the machine direction during manufacture. The film can have a basis weight of 100 gsm or less, 75 gsm or less, or 50 gsm or less, or from about 5 gsm to about 100 gsm, from about 15 gsm to about 75 gsm, from about 20 gsm to about 50 gsm, all of the above ranges including intermediate values ​​and combinable. In one embodiment, the film has a basis weight of 50 gsm or less.

[0021] The present invention further includes laminates comprising the films described herein. The laminates include a substrate attached to one or both surfaces of the film, and may include laminates comprising multiple films and multiple substrates.

[0022] The substrate may be any woven or nonwoven (NW) material that results in a laminate that is recoverably stretchable in multiple directions, including, but not limited to, spunbond (SB), meltblown (MB), or any combination thereof (e.g., spunbond-meltblown-spunbond, or "SMS"), as well as spunlace, spinlace, airlaid, carded, and / or bicomponent nonwovens. Particularly suitable nonwovens include spunlace nonwovens, such as those available from Suominen of Bethune, South Carolina. In one embodiment, the substrate is primarily stretchable in one direction, which is typically the cross direction during the manufacture of the laminate. The substrate may have a basis weight of about 100 gsm or less, alternatively about 50 gsm or less, alternatively about 25 gsm or less, alternatively about 1 gsm to about 100 gsm, about 25 gsm to about 75 gsm, alternatively about 25 gsm to about 50 gsm, all of the foregoing ranges including intermediate values ​​and combinable. The substrate may further have a peak load of <4 N / cm and / or a strain at peak of >100%.

[0023] In one embodiment, the laminate of the present invention is substantially free of intertwined elastomeric materials.

[0024] In one embodiment, the laminate of the present invention is substantially free of adhesives.

[0025] In one embodiment, when laminated, the primary stretch direction of the film is perpendicular to the primary stretch direction of the nonwoven fabric, and the resulting laminate is biaxially and / or multidimensionally stretchable.

[0026] Manufacturing method One example of an apparatus suitable for producing the films of the present invention is described in U.S. Patent No. 9,498,491 (Sablone et al.), available from Fameccanica Data SpA. The method generally described therein is also suitable for producing the laminates of the present invention, except for the differences described herein that contribute to the unique properties of the laminates claimed herein.

[0027] The films of the present invention may be coextruded, cast, blown, or formed by any other method that will result in the films described herein. In one embodiment, the film is preactivated prior to lamination, for example, by stretching in the machine direction (MD), cross direction (CD), or both.

[0028] The film may be stretched in one direction prior to lamination. A nonwoven substrate capable of stretching in a direction perpendicular to the direction in which the film is stretched may be laminated to the film while the film is stretched. The nonwoven may be laminated in a stretched or unstretched state.

[0029] The substrate may be laminated to the film by a variety of means, such as adhesive lamination, ultrasonic bonding, extrusion bonding, or other means known to those skilled in the art. In one embodiment, the laminate is ultrasonically bonded, and the resulting laminate includes ultrasonic welds or bonds.

[0030] The film and / or laminate may be stretched in the transverse direction using CD and / or MD interdigitation. The depth of interdigitation may vary from about 0.01 inches to about 0.250 inches, and in certain embodiments may be 0.120 inches, 0.140 inches, 0.160 inches, or 0.180 inches. Alternatively, the film and / or laminate may be stretched by diverging discs, as described, for example, in U.S. Patent Application Publication No. 2018 / 0042778 to Lenser et al., published February 15, 2018. In one embodiment, the diverging discs may be moved at a slower speed than the anvils to provide a simultaneous MD stretch to the film during ultrasonic lamination.

[0031] The film and / or laminate of the present invention are useful for various purposes, non-limiting examples of which include use in articles such as personal hygiene products, including absorbent products.Non-limiting examples of absorbent products include diapers, training pants, adult incontinence pads and pants, swimwear, sanitary napkins, panty liners, and / or absorbent pads or breathable shields to protect garments from fluids such as sweating in certain areas of the body.The laminate can be used, for example, as a backsheet, fastener, waistband, cuffs, and / or ears.In one embodiment, the laminate is incorporated into an absorbent article such as a diaper or adult incontinence product.

[0032] Working Example Laminates were made by stretching the film in the MD on a Fameccanica FMD-M2-00013 lamination system or other suitable production line and ultrasonically bonding the NW while the film was stretched. Three types of NW were used; 17gsm SMS, 25gsm SB (both available from Berry Global, Evansville, IN), and 25gsm spunlace (Suominen).

[0033] A three-layer film with ABA layer structure is used. The film is an OBC-based elastic film. The skin layer "A" is made of a PE / PP blend and 1-10% antiblock masterbatch and processing aids. The core layer "B" is made of a propylene-based OBC blend containing a mixture of INFUSE 9100, INFUSE 9507, INFUSE 9107 and / or DOW ELITE 5230. The core is approximately 85%-90% of the total thickness, the remainder being the skins. Unless otherwise stated, the basis weight of the film is 35gsm-45gsm.

[0034] The above films were not preactivated. Preactivating the film in the CD results in a laminate with a higher stretch ratio in the CD and makes the multidimensional stretching more symmetrical (data not shown).

[0035] Comparative films were also made with a core containing SBS and the same skin or A layers (data not shown). However, the SBS film could not be stretched more than twice its original length before breaking, and exhibited a high frequency of thermal failures known as "pop-outs," where the film melts and tears, resulting in areas in the laminate without film coverage. The size of the pop-outs was typically 5 mm. 2 For each film / NW combination, the film was mechanically stretched in MD during lamination by 300%, 400%, 500%, and 550%. Mechanical stretching was achieved by moving the anvil roll faster than the first nip roll. The MD stretch of the resulting laminate can be measured in three different ways: 1. The final laminate is stretched by hand (estimated stretch percentage) as follows: Two marks are made on the laminate, 10 mm apart. The laminate is stretched by hand until it reaches maximum stretch, i.e. the point where the sample cannot be stretched any further without being damaged. Measure the stretch distance, divide by 10, and multiply the result by 100 to get the stretch percentage. 2. Total elongation (unit: mm) when a tension of 1000g is applied to the laminate. 3. Elongation (%) at peak strain in tensile test.

[0036] The relative directional extensibility is defined as follows: 1) Elongation ratio (ER) (%)=(CD-elongation@1000g / MD-elongation@1000g)×100. 2) Peak elongation ratio (EAPR) (%) = (Peak CD elongation / Peak MD elongation) x 100.

[0037] Table 1 summarizes the measured stretchability of the final product at various applied strains by the machine during lamination, where the applied stretch is derived from the ratio of the anvil roll speed to the nip roll speed. For simplicity, a 50% stretch means that the film is stretched to half its original length during lamination.

[0038] [Table 1]

[0039] Table 2 summarizes the properties of the samples made with FMD-M2-00013. The films were stretched in the machine direction (MD) and then ultrasonically bonded while stretching. Therefore, the final laminate is MD stretchable, as shown in Table 2. When CD-stretchable spunlace NW was used, the final elastic laminate is stretchable in all directions (including CD and MD).

[0040] The CD load at 5% strain should have a very low value if the product is stretchable in CD since both the film and NW are easily deformed in CD. On the other hand, if the film or NW or both are not easily stretchable in CD, the CD load at 5% strain will be high and the laminate can only be stretched in MD. In the present invention, the film was stretched in MD only before lamination by ultrasonic bonding. The data in the second column of Table 2 show that the CD load at 5% strain for the samples made with spunlace NW (samples 8-11) has much lower values ​​than the CD load at 5% strain for the samples made with SB or SM nonwovens (samples 1-7). Samples 1-7 can only be stretched in the MD direction. All samples were made by stretching the film in MD before bonding and lamination. Therefore, all samples showed close low load values ​​at 5% MD strain. In other words, the MD load at 5% appears to be altered by the film only because the NWs are corrugated and do not exert significant forces in the MD until the film is stretched at least 100% in the MD.

[0041] [Table 2]

[0042] Figure 3 shows the CD and MD loading of various samples. Samples made with spunlaced NW have low 5% loading values ​​in both directions.

[0043] Figure 4 shows the peak elongation maps, where the sample made with spunlace NW has high peak values ​​in both directions.

[0044] Figure 5 shows that the laminate made with spunlace has high peak elongation in both MD and CD, however the other samples have low values ​​in CD because they are not stretchable in CD and high values ​​in MD because they are stretched in MD.

[0045] Figure 6 shows that the MD elongation of the laminate increases as the applied stretch increases. There was no significant difference between the samples made with SMS and SB NWs. However, the samples made with spunlace appear to have a higher elongation.

[0046] Figures 7 and 8 show that samples made with spunlace (CD stretchable NW) have much higher values ​​than samples made with SMS or SB NWs, i.e., laminates that are stretchable in both directions have high ER and EAPR.

[0047] All documents cited in the detailed description of the invention are, in relevant part, incorporated herein by reference, and the citation of any document shall not be construed as an admission that it is prior art with respect to the present invention. To the extent that a meaning or definition of a term in this document conflicts with a meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to that term in this document shall prevail. All ranges are inclusive and combinable. It is understood that unless a value is explicitly recited, when included in the recited range, it is implied as an option.

[0048] While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.

[0049] [Embodiment] (1) In the laminate, at least one elastomeric film comprising an olefin-based block copolymer, a styrenic block copolymer, or a combination thereof, and which is primarily extensible in a first direction; At least one spunlace nonwoven substrate that is primarily extensible in a second direction perpendicular to the first direction; Including, The laminate is multi-dimensionally stretchable. (2) The laminate of embodiment 1, wherein the laminate is uniformly multi-dimensionally stretchable. (3) The laminate of embodiment 1, having a ratio of CD elongation to MD elongation of 30% or more. (4) The laminate of claim 1, wherein the film has a basis weight of 50 gsm or less. (5) The laminate of claim 1, wherein the nonwoven has a basis weight of 50 gsm or less.

[0050] (6) The laminate of claim 1, wherein the laminate comprises an ultrasonic weld. (7) The laminate of claim 6, wherein the laminate is substantially free of adhesive. (8) In the laminate, at least one elastomeric film comprising an olefin-based block copolymer, a styrenic block copolymer, or a combination thereof, and which is primarily extensible in a first direction; At least one spunlace nonwoven substrate that is primarily extensible in a second direction perpendicular to the first direction; Including, A laminate, wherein the laminate is stretchable in both the first direction and the second direction. (9) The laminate of embodiment 8, wherein the ratio of CD elongation to MD elongation is 30% or more. (10) The laminate of embodiment 8, wherein the film has a basis weight of 50 gsm or less.

[0051] (11) The laminate of claim 8, wherein the nonwoven has a basis weight of 50 gsm or less. (12) The laminate of claim 8, wherein the laminate comprises ultrasonic welds. 13. The laminate of claim 12, wherein the laminate is substantially free of adhesive. (14) A method for producing a laminate, comprising the steps of: a. longitudinally stretching an elastomeric film comprising an olefin-based block copolymer, a styrene-based block copolymer, or a combination thereof; b. laminating the film to a spunlaced nonwoven substrate that is primarily extensible in the transverse direction while the film is being stretched in the longitudinal direction; A method comprising: 15. The method of claim 14, wherein the film is preactivated.

[0052] 16. The method of claim 14, wherein the film is not preactivated. 17. The method of claim 14, wherein the film is laminated to the nonwoven fabric by ultrasonic lamination, adhesive lamination, extrusion bonding, or a combination thereof. 18. The method of claim 14, wherein the film is stretched by 50% to 500% in the machine direction. 19. The method of claim 14, wherein the laminate is stretched in the transverse direction by interdigitation. 20. The method of claim 14, further comprising incorporating the laminate into an absorbent article.

[0053] (21) In the laminate, at least one elastomeric film comprising an olefin-based block copolymer, a styrenic block copolymer, or a combination thereof, and which is primarily extensible in a first direction; At least one spunlace nonwoven substrate that is primarily extensible in a second direction perpendicular to the first direction; Including, The laminate is multi-dimensionally stretchable. (22) The laminate of embodiment 21, wherein the laminate is uniformly multi-dimensionally stretchable. (23) The laminate of embodiment 21, wherein the ratio of the CD elongation of the laminate to the MD elongation of the laminate is 30% or greater. (24) The laminate of embodiment 21, wherein the film has a basis weight of 50 gsm or less and the nonwoven has a basis weight of 50 gsm or less. 25. The laminate of claim 21, wherein the laminate comprises ultrasonic welds.

[0054] (26) In a laminate, at least one elastomeric film comprising an olefin-based block copolymer, a styrenic block copolymer, or a combination thereof, and which is primarily extensible in a first direction; At least one spunlace nonwoven substrate that is primarily extensible in a second direction perpendicular to the first direction; Including, A laminate, the laminate being stretchable in both the transverse and longitudinal directions, and having a ratio of transverse stretch to longitudinal stretch of 30% or greater. (27) The laminate of embodiment 26, wherein the film has a basis weight of 50 gsm or less and the nonwoven has a basis weight of 50 gsm or less. 28. The laminate of claim 27, wherein the laminate comprises ultrasonic welds. (29) A method for producing a laminate, comprising the steps of: a. longitudinally stretching an elastomeric film comprising an olefin-based block copolymer, a styrene-based block copolymer, or a combination thereof; b. laminating the film to a spunlaced nonwoven substrate that is primarily extensible in the transverse direction while the film is being stretched in the longitudinal direction; A method comprising: 30. The method of claim 29, wherein the film is preactivated.

[0055] 31. The method of claim 29, wherein the film is not preactivated. 32. The method of claim 29, wherein the film is laminated to the nonwoven fabric by ultrasonic lamination, adhesive lamination, extrusion bonding, or a combination thereof. 33. The method of claim 29, wherein the film is stretched by 50% to 500% in the machine direction. 34. The method of claim 29, wherein the laminate is stretched in the transverse direction by interdigitation. 35. The method of claim 29, further comprising incorporating the laminate into an absorbent article.

Claims

1. A method for producing a laminate, comprising the steps of: a. longitudinally stretching an elastomeric film comprising an olefin-based block copolymer, a styrenic block copolymer, or a combination thereof; b. laminating the elastomeric film to a spunlaced nonwoven substrate that is primarily extensible in the transverse direction while the elastomeric film is being stretched in the longitudinal direction; A method comprising:

2. The method of claim 1 , wherein the elastomeric film is preactivated.

3. The method of claim 1 , wherein the elastomeric film is not preactivated.

4. 10. The method of claim 1, wherein the elastomeric film is laminated to the spunlaced nonwoven substrate by ultrasonic lamination, adhesive lamination, extrusion bonding, or a combination thereof.

5. The method of claim 1 , wherein the elastomeric film is stretched in the machine direction by between 50% and 500%.

6. The method of claim 1 , wherein the laminate is stretched in the transverse direction by intermeshing.

7. The method of claim 1 further comprising incorporating the laminate into an absorbent article.

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