KR19990028528A - Creased laminate of nonwovens and films - Google Patents

Abstract

The present invention relates to a corrugated laminate having a density difference generated in one or more layers of laminate. Laminate 10 includes a first layer 12 bonded to a second layer 14 forming a composite having a plurality of corrugations forming a series of peaks separated by a series of valleys. At least the second layer is formed of a compressible material, such as a fibrous nonwoven web, which forms regions of different densities due to the forming method used to form the laminate. In one method, the first and second layers are joined to each other along a series of bond lines 16 that are generally parallel, with at least one of the materials being in tension. Once the bond is terminated, the tension is removed, so the laminate forms a series of corrugations. In the bone region 18 immediately adjacent to the bond line, the laminate and in particular the second layer increase in density due to the bonding method. In the peak area 20 present between the valley areas, the laminate and in particular the second layer are of lower density. As a result, fluid entering the laminate through the first layer tends to fall into a denser area adjacent the bond line. This makes the material very suitable for use as a bodyside liner, in particular for personal absorbent products, with a reduction in the surface contact area of the first layer due to pleats.

Description

Creased laminate of nonwovens and films

A laminate is a composite material consisting of two or more layers or sheets of material bonded to each other. The resulting laminates can be used in many applications, including personal absorbent products such as diapers, training pants, feminine hygiene products such as sanitary napkins, incontinence devices, bandages and the like. All such products typically include a bodyside liner or cover, an outer cover or back sheet, and an absorbent core disposed between the bodyside liner and the outer cover.

Two of the most commonly used materials for constructing the bodyside liner and outer cover of the product are plastic films and fibrous nonwoven webs. Plastic films have the advantage of being liquid impermeable. As a result, plastic films are commonly used as the outer cover material of the product. When the plastic film is perforated or otherwise apertured, it passes through the liquid to make it available as a bodyside liner for the article. Nonwovens are generally liquid and gas permeable by design. As a result, nonwovens will easily pass body fluids such as urine and mens when used as bodyside liners. When the pore structure of such a nonwoven fabric is made sufficiently small, for example, the nonwoven fabric tends to be resistant to liquid penetration and thus may be used as an outer cover material. Finally, it is also possible to combine these films and nonwovens in various arrangements to form laminates that can be used for the same purpose.

Several disadvantages become apparent when the film and nonwovens, alone or in combination, are used as bodyside liners for personal absorbent products, especially when the material is used in connection with body fluids such as mens. Mens are very viscous in nature due to the composition of the blood base and the high particulate content when compared to other body fluids such as urine. As a result, it is often difficult to completely transport the material through the bodyside liner into the absorbent core until the product is discarded.

In view of personal hygiene, it is desirable for the user to separate the body fluids, such as urine and menses, as far as possible from the user's skin to provide a cleaner and drier feel. In addition, it is desirable for the bodyside liner to contact as little as possible with the user. Unfortunately, the material does not provide enough three-dimensionality to always provide the user with the clean and dry feeling. As a result, it is an object of the present invention to provide a material which can be used for this purpose and which can provide such a feeling. The material may also be used in a wide variety of other applications, which will become more apparent from the following detailed description, drawings, and claims.

Summary of the Invention

The present invention relates to a corrugated laminate comprising two or more layers of material. Laminates generally comprise a first sheet of material adhered to a second sheet of material at one or more points between the sheets, resulting in a series of peaks separated by a series of valleys. Many wrinkles are parallel. The laminate has a first density near the peaks and a second density near the valleys, where the second density is greater than the first density.

The materials capable of forming the first and second sheets vary widely and include, but are not limited to, films, wovens, nonwovens, foams, and laminates of one or more of the materials described above. In order to obtain a density difference between the peaks and valleys of the laminate, it is desirable to make the at least one material into a compressible web that can have a varying density. Fibrous nonwoven webs are just one example of such materials.

In addition to the difference in density, it is also possible for the laminate according to the invention to have a pore size difference. For example, if one or both of the first and second sheets are made of a compressible web, such as a fibrous nonwoven web, the laminate may have a first average pore size near the peaks and a second average pore size near the valleys. Where the first average pore size is greater than the second average pore size.

The size and spacing of the peaks and valleys will vary depending on the particular end use. Generally, however, the spacing between adjacent peaks of the laminate is about 2 to about 7 mm, and the vertical height of the laminate ranges from about 0.5 to about 5 mm, especially when the material is used in connection with a personal absorbent product.

Personal absorbent products include feminine hygiene products, including diapers, sanitary napkins and panty liners, incontinence devices, training pants, bandages and wipes. Such products will typically have a design that includes a bodyside liner and an outer cover and an absorbent core disposed therebetween. In addition, such products typically have a longitudinal axis and a transverse axis, which correspond to the longer dimension of the product.

The laminates of the present invention are particularly suitable for use as bodyside liners in such personal absorbent articles. Wrinkles serve to space the product away from the user and to improve comfort for the user by trapping solid particulate material in the valley of the wrinkle. As shown in the figure, the pleats may be disposed generally parallel to either or both of the transverse and longitudinal axes of the article. In a more specific embodiment, the bodyside liner has two lateral zones separated by a central zone and can be designed such that the pleats in the central zone are generally perpendicular to the pleats in the two lateral zones.

Several methods for forming the material according to the invention are described herein. In one method, the first and second layers of material are placed in a generally face to face relationship, followed by stretching at least one of the first or second layers. In the stretched state, the two layers are joined together in spaced and generally parallel bond lines to form a laminate. Once bonding occurs, the laminate is relaxed to form a number of corrugations that alternately comprise a series of peaks and valleys, with the laminate having a first density near the peaks and a second density near the valleys, where the second density is zero. Greater than 1 density. Depending on the device used, the method can be varied, for example by removing the stretching step and / or adding an adhesive between the first and second layers to further assist in bonding.

One apparatus used to form the laminate according to the invention comprises a first gear tooth roll having a plurality of teeth about the circumference, which teeth define a first angle between them. This first gear tooth roll is designed to be intermeshed with a second gear tooth roll having a plurality of teeth defining a second angle therebetween about the circumference. The angle is designed such that the first angle of the teeth on the first roll is greater than the second angle of the teeth on the second roll. As a result, the device can form a corrugated laminate according to the present invention while varying the density between peaks and valleys.

The present invention is directed to two or more layers of corrugated laminates, among other materials, capable of forming laminates using films and nonwovens. This laminate has a wide range of applications, including but not limited to cover materials for personal absorbent products.

1 is a side cross-sectional view of a pleated laminate of a nonwoven and a film in accordance with the present invention.

FIG. 2 is a partially cutaway perspective view of a personal absorbent article, in the case of a sanitary napkin using the pleated laminate of the nonwoven and film according to the invention as the bodyside liner of the personal absorbent article.

3 is a cross-sectional side view of the personal absorbent article of FIG. 2 taken along line 3-3 of FIG.

4 is a schematic side view of a method for forming a pleated laminate of a nonwoven and a film according to the present invention.

5 is a schematic side view of another method for forming a pleated laminate of a nonwoven and a film according to the present invention.

FIG. 6 is a partial side view of a pair of gear pleating rolls that may be used in connection with the method shown in FIG. 5.

7 is a plan view of a bodyside liner of a personal absorbent article using the laminate according to the present invention.

8 is a plan view of a bodyside liner of a personal absorbent article using the laminate according to the present invention.

9 is a plan view of a bodyside liner of a personal absorbent article using the laminate according to the present invention.

10 is a plan view of a bodyside liner of a personal absorbent article using the laminate according to the present invention.

11 is a photomicrograph of a material according to the invention as described in Example 1. FIG.

12 is a photomicrograph of a material according to the present invention as described in Example 2. FIG.

1 shows a laminate 10 according to the invention comprising a first layer 12 and a second layer 14. While this is the most basic embodiment of the present invention, it should be understood that more complex embodiments can be made by adding additional layers (not shown) to the laminate 10, and these additional embodiments are also within the scope of the present invention. It is also considered to be.

Both the first layer 12 and the second layer 14 can be made from a wide variety of materials including, but not limited to, films and fibrous nonwoven webs as well as mixtures of these two materials. As shown in FIG. 1, the first layer 12 is a layer of a film having a plurality of openings 13, and the second layer 14 is shown as a layer of fibrous nonwoven web material. Other materials can be used for one or both of the first layer 12 and the second layer 14. Examples of other materials include, but are not limited to, foams, tissues, coform materials, and combinations of the foregoing materials. When using the material according to the invention as a bodyside liner of a personal absorbent article, for example a sanitary napkin, it is preferred that at least one of the layers is a compressible web. This means that the web increases in density and decreases the average pore size of the structure at a defined area of the structure when applying compression and / or bonding techniques. Foams and fibrous structures such as wovens and nonwovens are particularly good examples of compressible webs. Examples of suitable nonwoven webs are bonded carded webs as well as air laid and wet laid webs, all of which are typically made from fibers of staple length or shorter. The fiber itself may be a blend of fibers, as well as natural or synthetic fibers, which may for example be a coform material. It has been found that synthetic fibers made of or comprising a thermally bondable material work particularly well because they not only thermally bond to each other but also thermally bond to other fibers that are beneficial when changing the density of the second layer, which Necessary for the present invention. To this end, it has been found that multicomponent and multicomponent fibers such as bicomponent and bicomponent fibers work particularly well. It is also possible to form one or both layers of the present invention using nonwoven webs made of more continuous fibers such as spunbond fibers and meltblown fibers. These fibers may also be made of single and / or multicomponent or multicomponent fibers.

Films used in the present invention can be prepared from a wide range of polymers in a wide range of thicknesses. If the liquid is to be passed through the laminate formed by the present invention, the film should be provided with openings or other pores of sufficient size to be able to pass through the liquid, including body fluids such as blood, urine or mens. In addition, if desired, the film layer can be made breathable, in particular when the laminate is used as the outer cover of the personal absorbent article. Breathability can be imparted, for example, by making the film breathable by using a filler in the film polymer blend, extruding the filler / polymer blend into the film, and then stretching the film sufficiently to create voids around the filler particles. In general, the more filler used and the greater the degree of stretching, the greater the degree of breathability. If the film is to be bonded to a fibrous nonwoven layer, it may be desirable to manufacture or design it to be thermally bondable to other layers of the laminate.

As will be explained in more detail below in connection with the detailed description of the method, the two layers 12 and 14 are formed in a number of ways in such a way that a plurality of species and / or transverse pleats or corrugations are formed in the laminate 10. Are joined to each other along the bond line 16. These bond lines can be continuous or discontinuous and will generally be parallel to each other. "Generally parallel" means that the bond lines themselves or the extension lines of the bond lines do not intersect with each other, or if they intersect, the cabinet formed by the intersection will be 45 ° or less.

Referring again to FIG. 1, in the compressible fibrous nonwoven layer (second layer 14), the region 18 adjacent to the bond line 16 is formed of the compressible web 14 which mediates the bond site 16. Have an increased density compared to the density of some 20. This is because the fibers of the compressible web 14 are more tightly compressed in the region 18 surrounding the bond line 16. As a result, the material in these regions has a higher density and smaller pore size than the material in the region 20 that mediates the bond lines.

With reference to FIGS. 2 and 3, the laminate material 10 of the present invention is a personal absorbent material having, for example, a second layer 14 or other internal component of the article 40 disposed adjacent the absorbent core 44. It can be used as bodyside liner 42 in article 40. The article 40 also includes some form of back or outer cover 46, such as a plastic film or other generally liquid impermeable material.

With respect to the film side of the laminate 10 adjacent to the user and the nonwoven side adjacent to the absorbent core 44, the laminate is through the first layer 12 in the raised or convex region 20 which mediates the bond line 16. Fluid entering 10 will pass through the first layer 12 and contact the low density portion of the nonwoven material 14. Due to the action we believe to be capillary action, this fluid will fall into the region 18 adjacent to the binding site 16, where the nonwoven fabric has a higher density, from which the fluid passes off into the absorbent core 44. something to do. In conclusion, the structure has a smaller affinity for body fluids in the raised or convex regions 20 adjacent to the wearer's skin and has a density around the binding site 16 where fluid can transfer to the absorbent core 44. The affinity for the fluid in the higher region 18 is higher.

As can be seen from the cross section of the material in FIG. 1, the laminate 10 has raised peaks separated by bone, the raised area or peaks being perpendicular to the less dense area 20, the valleys being Perpendicular to the bond line 16. As a result, the material is not suitable for use as a liner for sanitary napkins, incontinence devices or other products designed to receive and absorb particulates containing fluids, such as in the case of more viscous substances and / or blood, menses and excreta. Especially suitable. The materials that do not flow easily through the liner material can be collected in the bone, which in turn improves dryness and comfort by removing these materials from the user's skin.

With reference to FIG. 4, one method and apparatus for forming a material according to the invention is to stretch one of two layers 12 and 14 in one direction and then join the stretched layer to the non-stretched layer. Include. Once the two layers have been bonded to each other, the composite can be stretched, creased or pleated by releasing the stretching or pulling forces. Thus, for example, the nonwoven second layer 14 may be longitudinally stretched and then bonded to the film layer 12. Conversely, after stretching the film layer 12, it can be bonded to the non-stretched fibrous nonwoven second layer 14. To achieve this, the first layer 12, which is a film for illustrative purposes only, is dismissed from the first unwind 30, while the second layer 14, which is a fibrous nonwoven web, is a second disintegrator ( 32). The second layer is dissociated in such a way that it enters the coupling device 34 present in the stretching or tensile conditions. This is for example slower than the speed of the rotating surface of the corrugated joining roll 35, which is lower than the speed of the first disintegrator 30 / first layer 12 and which is part of the joining device 34. By braking and / or driving at speed. By stretching one of the two layers transversely to the bond line, the laminate is crimped between the bond lines 16, at which time the tension is removed. As shown in FIG. 4, the corrugated bond roll 35 imparts a bond line that transverses with respect to the longitudinal direction of the material. Alternatively, the corrugated bond roll 35 can have teeth running parallel to the longitudinal direction of the device, in which case the stretching of one of the layers must be transverse.

As shown in FIG. 4, the engaging and crimping device 34 includes a crimping or gear tooth engaging roll 35 and an ultrasonic horn 38. When the ultrasonic horn is actuated, each of the raised tooth portions of the engagement roll 35 contacts the horn 38 so that engagement occurs while engagement does not occur between the teeth. As a result, a bond line is achieved between the first layer 12 and the second layer 14, the nonwoven material is pressed more densely at the joining site 16, and the region 18 mediates the region 18. It immediately surrounds the binding site 16 relative to the convex portion 20. Once the bonding of the two layers is complete, the tension is removed to allow the laminate to relax to improve pleats or pleats in the laminate 10 and to be wound onto the winding rolls 39. In addition, an adhesive spray application vessel 33 is disposed between the two layers 12 and 14 to bond the layers of adhesive to one or both of the layers 12 and 14, or to combine them after To the device 34.

An important feature of the above method is the pleat or pleat caused by stretching one of the first and second layers and joining the layers together and then stretching the entire laminate. The pleats or pleats make the laminate thicker and bulkier by increasing the total surface area per unit area of the laminate 10.

A second method and apparatus for forming the laminate 10 according to the invention is shown in FIG. 5. This method is similar to the method shown in FIG. 4 and is executed in the same way. As a result, like reference numerals are used for like parts. The main difference is the coupling device 34.

The engagement device 34 of FIG. 4 comprises a gear tooth coupling roll 35 and an ultrasonic horn 38. In FIG. 5 the ultrasonic horn 38 was replaced with a second gear tooth engaging roll 36 designed to intermesh with the first gear tooth engaging roll 35. In order to cause bonding and / or densification, it is desirable to apply heat to one or both of the webs immediately before or during bonding. As a result, one or both of the bonding rolls 35 and 36 can be heated to thermally bond the two layers of material together. If the bonding rolls are not heated, preheating of the web must be carried out, for example using an infrared or air passage bonding device 37 disposed immediately in front of the coupling device 34. Alternatively or in addition to one or both of the webs, an adhesive spraying vessel 33 is disposed between the two layers 12 and 14 to spray or to the adhesive to one or both of the layers 12 and 14 or After other applications they can be introduced into the joining and creasing device 34.

In FIG. 6, the first gear tooth engaging roll 35 has a plurality of teeth 50 designed to intermesh with the valleys 51 between the teeth 53 on the second gear tooth engaging roll 36. The vertices 55 of each tooth 50 form an angle A, while the valleys 51 between the teeth 53 of the engagement roll 36 form a second angle B. Angle A is designed to be larger than angle B. As a result, between the apex 55 of the gear tooth roll 35 and the valley 51 of the gear tooth roll 36, the valley 54 of the apex 57 of the gear tooth roll 36 and the gear tooth roll 35 54. There is a larger area than exists between). Thus, when the laminate is formed using the nonwoven layer 14 adjacent to the first roll 35 and the film layer 12 adjacent to the second roll 36, the valleys 51 of the second roll 36 are formed. ) Will be greater in the area adjacent the valleys 54 of the first roll 35 than the two layers are pressed together. This will provide a laminate similar to that described in FIGS. 1-3, where the bond line 16 is formed in the region where the peaks 57 of the roll 36 and the valleys 54 of the roll 35 intermesh. It should be noted that if each A and B are the same, there is a uniform density throughout the laminate, but as the difference between each A and B increases, the density gradient will also increase. The degree of densification can be further varied by adjusting the gap between the two rolls 35 and 36. Smaller gaps will increase densification.

A variation of the two methods described above is to impart pleats or pleats to the laminate by making one of the two layers from a heat stretchable or heat shrinkable material. Examples of such materials are elastomeric materials made from oriented films and resins that are not heat cured, including polyurethanes, polyesters, polyolefins, and polyacetates. In this method, the heat shrinkable layer, which is a film, nonwoven or other material, is bonded to the other layer using one of the bonding mechanisms described above, and once bonded, the laminate is crimped by stretching it with sufficient heat to induce a heat shrinkable layer. Or pleat. Here too, either the first layer or the second layer can be made heat shrinkable. The amount of heat required to effect shrinkage should be noted, although it will not break the bonds between the layers.

Yet another means of imparting pleats or pleats to the laminate includes stretching one of the layers and bonding it to another layer made of a heat shrinkable material. Once the two layers are joined, two means can be provided for the same laminate to create tension or pleats by relaxing the tension of the stretched layer and applying heat to the laminate.

Although the materials, devices, and methods of the present invention have been described, it will be apparent that various modifications may be made to the present invention. For example, FIGS. 7-10 illustrate some additional bodyside liner designs that may utilize the present invention. 7 shows the bodyside liner 90, which is also a straight line, is not continuous but instead is a broken line. Such bond dashed lines still form wrinkles and are consequently considered to be within the scope of the present invention and the term "bond line".

8 shows a bodyside liner 100 having two side zones 102 and 104 separated by a central zone 106. As can be seen from the figure, the central zone 106 contains wrinkles while the lateral zones 102 and 104 are free of any wrinkles. FIG. 9 is the same as FIG. 10 except that the corrugations in the central region 106 are generally parallel to the longitudinal axis 110 and generally perpendicular to the transverse axis 112, while the corrugations of FIG. 8 are longitudinal axes. Perpendicular to 110. "Generally vertical" means that the bond line or its extension line intersects at a cabinet greater than 45 ° and less than 90 °. Finally, in FIG. 10, the bodyside liner 100 has wrinkles in all zones 102, 104, and 106, with wrinkles in the central zone 106 being in the lateral zones 102 and 104. Generally perpendicular to the folds. Of course, the direction of the wrinkles in zone 106 may be reversed as compared to zones 102 and 104.

The materials and methods of the invention have been described and several sample materials have been prepared and tested to demonstrate the invention. Test procedures and examples are described below.

Test procedure

Several test methods were used to evaluate the properties of the material according to the invention. The method of measuring these characteristics is described next.

Intake and Rewet Test

Absorption time tests are indicative of the intake rate for a material or laminate using a synthetic mens fluid. The composition of the synthetic mens fluid consisted of approximately 82.5 weight percent water, 15.8 weight percent polyvinyl pyrrolidone and 1.7 weight percent salts, colorants and surfactants. Its viscosity is 17 centipoise and the surface tension is 53.5 dyn / cm. A 3 inch by 5 inch (7.6 cm by 12.7 cm) sample of test material was placed on top of the nonabsorbent surface and the synthetic mens fluid delivered from a fluid reservoir having a 2 inch by 0.5 inch (5.1 cm by 1.3 cm) delivery slot. 10 kPa was discharged. Blocks are indicated by level lines to indicate when 8/10 Hz has been delivered. Subsequently, the time to absorb 8 Hz was measured in seconds. Smaller absorption times, measured in seconds, indicate faster intake rates for certain materials. The values reported in the examples were based on the average of five samples.

After measuring the time to absorb 8 kPa of fluid, an additional 1 minute of time elapsed to allow more 2 kPa of fluid in the delivery block to be absorbed into the sample. Next, the transfer block was removed and a pre-weighed blotter was placed on top of the sample and a pressure of 1 lb / in ² (0.070 kg / cm 2) was applied to the blotter and the specimen for 3 minutes. At the end of three minutes the blotter was removed and weighed, and the amount of synthetic mens fluid absorbed in the blotter was measured in grams, indicating the extent of resorption. Higher values indicate a greater degree of resorption for the particular material tested. The values reported in the examples were based on the average of five samples.

thickness

The thickness of the material, including the laminate, was measured using the Starrett Bulk test. In this test, a 12.7 × 12.7 cm sample of material was pressed under a 0.05 lb / in ² (3.5 g / cm 2) load and the thickness measured under this load. Larger numbers indicate thicker materials. Five samples for each material were measured and averaged. The given value is an average value.

Basis weight

The basis weight of the various materials described herein was measured according to Federal Test Method No. 191A / 5041. The sample size for the samples was 15.24 × 15.24 cm and averaged after obtaining three values for each material. The values reported below are average values.

Pore size and density gradient test

Pore size gradients and density gradient measurement methods are described below. The method involves taking some representative cross sections of a laminate sample and imaging the cross sectional fibrous network by image analysis. The pore size is determined by measuring the distance between fibers as the image is scanned from the bond line to the bond line and recorded in mm. Density gradients are calculated by measuring the vertical height of several scan lines from the bond line to the bond line and dividing the basis weight by the measured height.

Sample manufacture

The cut surface of the sample was placed face up in the encapsulation mold. Sufficient inclusion media was added to fully saturate and surround the sample. If the sample was suspended after curing and a portion of the sample was not fully enclosed, additional media was added to cure.

The cured mold was trimmed with an abrasive belt to expose the sample to provide a cross section of the sample by providing a plane parallel to the Y-Z plane of the sample. This cross section was cut into a microtome and mounted on a glass microscope slide.

Two to three light micrographs were obtained from each of two to three cross sections for the sample to provide six light micrographs per sample. Photographic exposure was adjusted to provide bright fibers against a black background.

Sample size: 0.75 in (19.1 mm) × 1.5 in (38.2 mm) MD parallel to the short dimension

Enclosure Mold: 1 in (25.4 mm) × 1.75 in (44.5 mm) × 0.75 in (19.1 mm) depth

Encapsulation Medium: LADD Ultra Low Viscosity Epoxy (use blend recommended for medium hardness blocks)

Microtome: Rachael Polycut E with Tungsten Carbide Type D Knives

Section thickness: 25 ㎛

Microscope Slide: 2 in (50.8 mm) × 3 in (76.2 mm) glass

Cover Slide: 24 mm x 50 mm glass

Mounting medium: Resolve brand microscope immersion oil n _D = 1.5150

Microscope: Leica Wild M-420 Makroskop

Camera: Leica with Polaroid Sheet Film Back

Film: Polaroid T-53 (ASA 800), 4 in (101.6 mm) × 5 in (127.0 mm) constant sheet film

Magnification: 10.3X

Exposure conditions: Intermittent lighting, dark field

Measurement technology

Measurements were made by image analysis by QUALTIMET 970 (Cambridge Instruments, Deerfield, Illinois) Macroviewer using a 35 mm lens, autostage as space, 65 cm camera pole position, and four incident flood lamps. Pore size gradients were injected using computer program # 1 and density gradients were injected using computer program # 2. The results are shown in Tables 1 and 2.

Computer program # 1

Computer program # 2

<Example 1>

In Example 1 a film / nonwoven laminate was prepared according to the method described above in FIG. 4. The base film was a 1 mil (0.00254 cm) thick low density polyethylene film containing 4% by weight of titanium dioxide (TiO ₂ ) uniformly dispersed throughout the film. The film polymer was NA-206 Low Density Polyethylene (LDPE) from Quantum Inc., Wallingford, Connecticut. TiO ₂ was in concentrated form and was obtained from Ampaset Company (designated by Ampacet Company, Mount Vernon, New York, 110313). The film once formed was mechanically apache with an open area of about 25%. The diameter of the individual openings was about 550 microns (average circular diameter). The film thickness after Apacheing was about 0.015 inches (0.0381 cm).

The compressible fibrous nonwoven web portion of the laminate was a bicomponent spunbond web with a basis weight of 34 g / m 2 (gsm). The fibers had a side by side configuration of 5 deniers and 28.2 microns in diameter. The fibers contained 50% by weight of Exxon 3445 polypropylene from Exxon Chemical Company, Darien, Connecticut and 50% by weight of Dow Grade 6811A polyethylene from Dow Chemical Company, Midland, Michigan. The web was bonded through air at 267 ° F. (128 ° C.) with less than 1 second of down time. The web was treated with 0.4% Y12488 polyalkylene oxide modified polydimethylsiloxane nonionic surfactant wet package based on dry basis weight and total weight of the web. The surfactant was a product of OSi Specialties, Inc., Danbury, Conneticut. The web thickness was 0.1524 cm. Such bicomponent webs may be prepared according to US Pat. No. 5,336,552 (Strack et al.), Which is incorporated herein by reference in its entirety.

The film was fed to the joining device so as to be adjacent to the gear tooth joining roll and operated at about the same speed as the gear tooth joining roll having a rotational surface speed of 5 m / min. The gear tooth coupling roll was not heated and was at an ambient temperature of about 20 ° C. The diameter of the gear tooth coupling roll measured 6.173 inches (15.7 cm) from the tooth top to the tooth top. The saw tooth had flat top and vertical sides. The tooth width was 0.025 inch (0.635 cm). The vertical depth of the teeth was 0.254 cm and the tooth to tooth spacing was 0.18 inch (4.57 mm) (centerline to centerline). The ultrasonic horn used prefabricated in the coupling device was from Branson Ultrasonics Corporation, Danbury, Connecticut. The horn itself was a 9 inch (23 cm) horn with a gold booster with an acquisition ratio of 1 to 1.5. The booster was connected to a model 900 actuator, which in turn was connected to a model 900B 300 watt / 20,000 kW power supply. For Example 1 the horn was adjusted to 50% output. The nonwoven web was placed adjacent to the ultrasonic horn and fed to the bonding device at about 2/3 the speed of the bonding roll. As a result, the nonwoven web was stretched about 50% and then bonded to the film layer. The laminate was recovered after the bonding step and relaxed to cause wrinkles in the laminate.

A cross sectional side view of the laminate is shown in FIG. 11. As can be seen from the photograph of FIG. 11, the laminate reduced the contact area of the skin on the film side due to the wrinkling of the two materials. The overall height or thickness of the folds at the highest point was about 1.1 mm. The spacing between adjacent vertices was about 4.5 mm and the spacing between adjacent bond lines was about 4.5 mm. It is understood that this wrinkle effect is advantageous to allow more air circulation and less skin contact, which is particularly important when the material is wetted by, for example, urine or mens. The interfiber spacing on the nonwoven side of the laminate opens larger than the interfiber spacing in the area adjacent the apex of the pleats. In contrast, the fiber spacing in the area of the fibrous nonwoven web relative to one side of the bond line is much closer, thus forming a higher density fiber structure compared to the above-mentioned area mediating the bond line. As a result, it can be seen that the nonwoven side has a two-dimensional zone of a low density zone at the apex of the corrugation which approximately mediates two adjacent bond lines and a higher density zone on either side of the bond line. As a result, a density difference is formed between the top and the bottom of the wrinkles, which also create a pore size gradient, from the top of the wrinkles where fluid may be present in close proximity to the wearer's skin, typically as an absorbent core of a personal absorbent product. Facilitate flow towards the bond line close to the absorbent material.

Density measurement of the laminate was done according to the test procedure described above. The density of the nonwoven web portion of the laminate (assuming little or no density change in the density of the film layer) at the midpoint between the bond lines at the proximal apex of the corrugation is 0.023 g / cm 2 (g /,), while directly at the bond line The density of the nonwovens in the adjacent areas was about 0.173 to 0.236 g / mm 3 based on the average of 10 samples of the material of Example 1 (see Table 1). In addition, as shown in Table 1, the density value gradually increases from the vertex in either direction for the region adjacent to the bond line.

Example 1 Example 2 Density (g / ㏄) Density (g / ㏄) Area adjacent to the join line 0.291 0.200 0.173 0.090 0.070 0.047 0.047 0.032 0.035 0.027 0.030 22 0.029 0.019 0.027 0.019 0.026 0.017 0.025 0.018 0.025 0.018 Vertex 0.024 0.017 0.026 0.019 0.025 0.022 0.028 0.026 0.029 0.031 0.032 0.038 0.044 0.048 0.057 0.096 0.108 0.125 0.236 0.150 Area adjacent to the join line 0.358 0.351

In addition, the pore size measurement of the laminate was made according to the test procedure described above. The pore size of the nonwoven web portion of the laminate at about midline between the bond lines at the proximal apex of the corrugation is about 0.65 mm, while the density in the area immediately adjacent to the bond lines is approximately based on the average of 10 samples of the material of Example 1 0.21 to 0.29 mm (see Table 2).

Example 1 Example 2 Pore Size (mm) Pore Size (mm) Area adjacent to the join line 0.29 0.26 0.57 0.49 0.41 0.62 0.52 0.94 0.63 0.78 0.62 0.91 0.61 0.85 0.69 0.87 0.62 0.82 Vertex 0.65 0.98 0.67 0.78 0.59 0.99 0.76 0.94 0.59 0.90 0.49 0.66 0.62 0.56 0.41 0.56 Area adjacent to the join line 0.21 0.31

The fluid handling performance was tested using the intake time and rewet test described above for the film nonwoven laminates of this example. Samples of the laminate were cut and placed on top of a two-layer absorbent core with a nonwoven side adjacent to the absorber for simulating a personal absorbent product, in this case a female pad or sanitary napkin cover material. The thermoplastic film layer was disposed on the back side of the pad. The upper bodyside layer of the core was 425 gsm fluff with a density of about 0.07 g / dL and the baffle side layer was 470 gsm fluff with a density of about 0.094 g / dL. The baffle side layer was embossed with an acorn pattern.

The fluid handling performance of the laminate materials was compared in a laminate or non-laminate state of the same components. The nonwoven and apache film were thus cut separately and laminated on top of a two layer absorbent core with a nonwoven material disposed adjacent to the absorbent core.

Fluid intake time and resorption were tested using the synthetic mens fluid described above for the laminate and laminated cover material samples. The test results are shown in Table 3 below.

Intake time (seconds) Rewet (g) Thickness (mm) Creased Film / NW 11.47 0.25 1.63 Laminated Film / NW 12.38 0.56 1.19

As is very evident from the data provided above, the corrugated laminate material according to the present invention has improved intake time and significantly reduced rewet compared to the same laminate structure. Thus, the fluid was absorbed more quickly by the feminine pads and less rewet to the surface. This reduction in rewet is believed to be due in part to the increased separation between the wearer and the fluid absorbed in the absorbent core caused by the wrinkles, as can be seen from the significant increase in the thickness of the wrinkled laminate. In addition, the reduction in rewet is believed to be due to the concentration gradient created within each pleat that carries and retains the fluid from the user and thus less fluid rewet to the surface.

<Example 2>

In Example 2, a nonwoven / nonwoven laminate was prepared under the same conditions and with the same materials as in Example 1 under the same conditions. Only one difference was that the film layer was a 14 g / m 2 spunbond polypropylene web containing 4 wt.% TiO ₂ based on the total weight of the fiber / web. Polypropylene resin was E5D47 and was obtained from Shell Chemical Company. TiO ₂ was obtained from the same supplier as Example 1 and was designated 41438. The denier of the fibers forming the web was 5 and the diameter was 28.2 microns. The webs were thermally point bonded with a bonding area of about 15%. The bond pattern consisted of staggered rows of diamond-like bond points with sides of equal length, with a bond area of about 0.009 in ² (0.058 cm 2). The web was treated with 0.5% Triton X-102 nonionic surfactant (Union Carbide Company, Sisterville, Virginia) based on dry basis weight and total weight of the web.

The other nonwoven web was the same bicomponent spunbond web used in Example 1. Two webs were fed to the apparatus in the same manner as in Example 1, with 14 gsm of polypropylene spunbond web adjacent to the gear tooth coupling roll and the ultrasonic horn set to 60% power. The resulting laminate is shown in cross section in FIG. 8. The overall height of the folds was on average about 2 mm at the highest point. The spacing between adjacent vertices was about 4 mm and the spacing between adjacent bond lines was about 4 mm. Once again, it is understood that this wrinkle effect is advantageous to allow more air circulation and less skin contact, which is particularly important when the material is wetted by, for example, urine or mens. Like the laminate of Example 1, the spacing between the fibers is opened larger than the interfiber spacing in the area adjacent to the apex of the pleats. In contrast, the fiber spacing in the area of the fibrous nonwoven web relative to one side of the bond line is much closer, thus forming a higher density fiber structure compared to the above-mentioned area mediating the bond line. As a result, it can be seen that the nonwoven side has a two-dimensional zone of a low density zone at the apex of the corrugation which approximately mediates two adjacent bond lines and a higher density zone on either side of the bond line. As a result, a density difference is formed between the top and the bottom of the wrinkles, which also create a pore size gradient, from the top of the wrinkles where fluid may be present in close proximity to the wearer's skin, typically as an absorbent core of a personal absorbent product. Facilitate flow towards the bond line close to the absorbent material.

The density measurements of the laminates were made according to the test procedure described above and reported in Table 1. The density of the nonwoven web portion of the laminate at the midpoint between the bond lines at the proximal peaks of the corrugation is 0.017 g / cm 2 (g / dl), while the density of the nonwoven fabric in the area immediately adjacent to the bond lines is 10 of the materials of Example 2 It was about 0.15 to 0.20 g / dl based on the sample mean.

In addition, the pore size measurement of the laminate was made according to the test procedure described above. The pore size of the nonwoven web portion of the laminate at about midpoint between the bond lines at the close apex of the corrugation is about 0.98 mm, while the pore size in the area immediately adjacent to the bond lines is based on the average of 10 samples of the material of Example 2 It was about 0.26 to 0.31 mm (see Table 2).

The fluid handling performance was tested using the intake time and rewet test described above for the nonwoven / nonwoven laminates of this example. Laminate materials were prepared and tested similar to the procedure described in Example 1. As in Example 1, the bicomponent spunbond web was placed adjacent to the absorbent core. The fluid handling performance of the laminate materials was compared relative to the same material component in either the laminated or unlaminated state. Thus each nonwoven material was cut separately and laminated on top of a two layer absorbent core with a nonwoven material disposed adjacent to the absorbent core. The test results are shown in Table 4 below.

Intake time (seconds) Rewet (g) Thickness (mm) Creased Film / NW 9.05 0.42 1.24 Laminated Film / NW 15.90 0.87 1.19

As in Example 1, the corrugated laminate material once again demonstrates the positive effect of wrinkles on fast fluid intake and reduction of rewet, as the intake time is improved and the rewet value is significantly reduced. Unlike Example 1, the rewet decreased significantly, but the thickness did not increase significantly. It is believed that the fluid is imparted to a bicomponent nonwoven web moving from the user towards the absorbent core, demonstrating the importance of density gradients to improve separation between the bodyside surface and the absorbent and to minimize fluid resorption.

As can be seen from the embodiments described above, corrugated laminates have improved fluid intake and rewet performance compared to the same non-creased laminate. It is believed that this coincides with a faster mens absorption and a drier feeling surface, which is a desirable advantage in use. Corrugation is important for such use because it increases the separation between the user and the fluid in the absorbent core and minimizes the amount of material in contact with the user. In addition, the difference in density between the top and bottom of the wrinkles and the resulting pore size provide the user with a sanitary napkin that easily absorbs mens and maintains a clean, dry feel on the body side surface.

As such, while the invention has been described in detail, it will be apparent that various modifications and changes can be made in the invention without departing from the spirit and scope of the invention.

Claims (15)

A first sheet adhered to the second sheet at one or more points between the first and second sheets for forming the laminate, The laminate has a plurality of generally parallel folds forming a series of peaks separated by a series of valleys, the laminate having a first density near the peak and a second density near the valley, 2 density is greater than said first density. The laminate of claim 1 wherein the first sheet is a liquid transmissive film and the second sheet is a compressible web. 3. The laminate of claim 2, wherein the compressible web is a fibrous nonwoven web. 3. The fibrous nonwoven web of claim 2, wherein the fibrous nonwoven web has a first average pore size near the peaks, a second average pore size near the valleys, and wherein the first average pore size is greater than the second average pore size. The laminate which is big. The laminate of claim 1 wherein the spacing between adjacent peaks of the laminate is about 2 to about 7 mm. The laminate of claim 1 wherein the laminate has a vertical height of about 0.5 to about 5 mm. A personal absorbent article comprising a bodyside liner and an outer cover and an absorbent core disposed therebetween, wherein the bodyside liner comprises the laminate of claim 1. 8. The personal absorbent article as in claim 7, wherein said article has a longitudinal axis and a transverse axis and said wrinkles are generally parallel to said longitudinal axis of said article. 8. The personal absorbent article as in claim 7, wherein said article has a longitudinal axis and a transverse axis and said pleats are generally parallel to said transverse axis of said article. 8. The body of claim 7 wherein the bodyside liner has two side zones all separated by a central zone containing wrinkles, wherein the wrinkles of the central zone are generally perpendicular to the wrinkles of the two side zones. Personal absorbent product. Providing the first and second layers of material in a generally face to face relationship, Stretching at least one of the first and second layers, Combining the first layer and the second layer together at a spaced and generally parallel centerline to form a laminate, Relaxing the laminate to form a plurality of wrinkles comprising alternating series of peaks and valleys, Wherein said laminate has a first density near said peaks and a second density near said valleys, said second density being greater than said first density. 12. The method of claim 11 further comprising applying an adhesive between the first and second layers prior to the bonding step. Providing the first and second layers of material in generally facing relationship, The first layer and the second layer are joined together in spaced and generally parallel bond lines to have a plurality of corrugations that alternately contain a series of peaks and valleys, having a first density near the peaks and near the valleys. Forming a laminate having a second density, the second density being greater than the first density Method of producing a wrinkled laminate comprising a. The method of claim 13, further comprising applying an adhesive between the first and second layers prior to the bonding step. A first gear tooth roll having a plurality of teeth about a circumference, wherein the teeth on the first roll define a first angle between the teeth, A second gear tooth roll having a plurality of teeth about the circumference, wherein the teeth on the second roll define a second angle between the teeth, Corrugated teeth on the first and second rolls with each other to form a gap therebetween, wherein the first angle of the teeth on the first roll is greater than the second angle of the teeth on the second roll Apparatus for forming the material.