JP2002543304A - Stretch non-woven material - Google Patents

Abstract

(57) An elastic nonwoven material comprising a nonwoven web having a plurality of bicomponent fibers comprising a polyester and a second polymer, wherein the nonwoven web is patterned or point bonded. Is heated after formation. The second polymer is preferably a polyolefin such as polyethylene or polypropylene.

Description

DETAILED DESCRIPTION OF THE INVENTION

TECHNICAL FIELD [0001] The present invention relates to a nonwoven material that does not contain a thermoplastic elastomer or rubber but exhibits elastomeric properties. More particularly, the present invention relates to non-woven materials that are stretchable in the machine and / or cross directions without the use of thermoplastic elastomers or rubber. The nonwoven material exhibits elastic recovery in both the machine and cross directions when stretched up to about 30%. The material is particularly suitable for use in personal care absorbent articles, such as diapers, training pants, and adult incontinence clothing.

BACKGROUND OF THE INVENTION Absorbent personal care articles, such as sanitary napkins, disposable diapers, incontinence care pads, are widely used, and many efforts have been made to improve the effectiveness and functionality of such articles. It has been done. Previous thick, flat care articles that do not closely conform to the shape of the human body and do not conform to the movements of the user have already been largely replaced by articles having a three-dimensional body shape that elastically conforms.

[0003] A nonwoven web is defined as a web that is not regular or identifiable as in a knitted fabric, but has a structure of individual fibers or yarns that intersect each other. Nonwoven webs can be formed by a number of methods, such as, for example, meltblowing, spunbonding, and bonded carded web methods. Typically, fibers made in such a manner are deposited on a forming wire or belt for web formation. Non-woven webs tend to shrink when subjected to heat treatment following web formation. Shrinkage of nonwoven webs is generally considered disadvantageous in that it introduces non-uniformity in the web. Production of nonwoven polymer fabrics where the continuous melt-spun multicomponent polymer filaments are crimped before the continuous multicomponent filaments are formed into the nonwoven web, resulting in a significant reduction in shrinkage and a substantially stable and uniform nonwoven web. See, for example, U.S. Patent Nos. 5,382,400 and 5,418,045, both to Pike et al., Which teach methods.

[0004] However, diapers, training pants, and incontinence garments made of substantially stable and uniform nonwoven materials may not be compatible with the movements of the wearer, and the comfort and possibly functionality of the article It will be apparent that the To date, this problem has been addressed by articles using elastic films, as well as articles having a resiliently conforming three-dimensional body shape, as described above.

[0005] One object of the present invention is to provide a nonwoven web material that exhibits elasticity. It is another object of the present invention to provide a nonwoven web material that exhibits elasticity and does not use any thermoplastic elastomers or rubbers. These and other objects of the present invention are addressed by a stretchable nonwoven material comprising a nonwoven web comprising a plurality of bicomponent fibers having a polyester and a second polymer, wherein the nonwoven web comprises After formation, they are pattern bonded or point bonded and then heated. Suitable polyesters for use in the present invention are any polyesters that shrink when heated. According to one particularly preferred embodiment, the polyester is polyethylene terephthalate (PET). The second polymer is one that does not shrink as much as polyester when heated, and is preferably a polyolefin or polyamide. The resulting stretchable nonwoven material can be stretched in the machine direction and / or cross-machine direction up to about 130% of its unbiased length. Upon release of the biasing force, the nonwoven material exhibits elastic recovery in both the machine and cross directions and substantially returns to its original dimensions. Depending on the polyester and second polymer used to form the fiber, the fiber can be made to tear. These and other objects and aspects of the present invention will be better understood from the following detailed description, taken in conjunction with the drawings.

[0006] (BEST MODE FOR CARRYING OUT THE INVENTION) Definitions The term "stretchable" is extendable to a biasing length as used herein, is stretched and applying a biasing force, the Releasing the stretching and stretching force means any material that will recover at least 50% of its stretch. A hypothetical example is a one-inch sample of material that is extensible to at least 1.50 inches (50% elongation) and stretched to 1.50 inches to release 1.
It will recover to a length not exceeding 25 inches (50% recovery).

[0007] As used herein, the term "nonwoven web" or "nonwoven material"
A web having the structure of individual fibers or yarns interleaved with each other in a regular or discernable manner as in a woven fabric or fibrillated film. Nonwoven webs or materials have been formed by a number of methods, such as, for example, meltblowing, spunbonding, and bonded carded web methods. The basis weight of a nonwoven web or material is usually expressed in ounces per square yard of material (osy) or grams per square meter (gsm), and the usable fiber diameter is usually expressed in microns. (To convert osy to gsm, set osy to 33.9.
Note that it is multiplied by one. )

As used herein, the term “spunbond fibers” refers to a diameter of the diameter formed by extruding molten thermoplastic material as filaments from a plurality of thin, usually circular, spinneret capillaries. Meaning smaller fibers, the diameter of the extruded fibers is then rapidly reduced, and the method is described, for example, in U.S. Pat. No. 563, U.S. Pat. No. 3,692,618 to Dorschner et al., U.S. Pat. No. 3,802,817 to Matsuki et al., U.S. Pat. No. 3,338, U.S. Pat. No. 992 and U.S. Pat. No. 3,341,394; U.S. Pat.
No. 502,763; U.S. Pat. No. 3,502,538 to Levy and U.S. Pat. No. 3,542,615 to Dobo et al. Spunbond fibers are quenched and are generally not tacky when deposited on a collection surface. Spunbond fibers are substantially continuous and have an average diameter of greater than 7 microns, and more particularly between about 10 and 35 microns.

As used herein, the term “meltblown fiber” refers to the passage of a molten thermoplastic material through a plurality of narrow, usually circular, mold capillaries to reduce the diameter of filaments of the molten thermoplastic material. Means a fiber formed by extrusion as a molten yarn or filament into a converging high-velocity gas stream (eg, a gas stream) that narrows to a microfiber diameter. Thereafter, the meltblown fibers are carried by the high velocity gas stream and accumulate on the collection surface, forming a web of randomly dispersed meltblown fibers. Such a method is disclosed, for example, in U.S. Pat. No. 3,849,241 to Butin. Meltblown fibers are microfibers that can be continuous or discontinuous, generally having an average diameter of less than 10 microns, and are generally tacky when deposited on a collection surface.

[0010] As used herein, the term "bonded carded web"
A web made of staple filaments that is fed through a combing or carding device that separates the staple filaments into machine direction and forms a substantially machine-oriented fibrous nonwoven web. Such fibers are
Usually purchased in bulk and placed in a sorter that separates the fibers before going to the carding equipment. Once the web is formed, the web is then bonded in one or more of several known bonding methods.

As used herein, the term “microfiber” refers to, for example, an average diameter of about 0.5 microns to about 50 microns, and more specifically, an average diameter of about 2 microns to about 40 microns. Fiber means a small diameter fiber having an average diameter not exceeding about 75 microns. Another commonly used expression for fiber diameter is denier, which is defined as grams per 9000 meters of fiber, which is the square of the fiber diameter in microns and the density in grams / cubic centimeter. And then multiply by 0.00707. A lower denier indicates that the fiber is thinner, and a higher denier indicates that the fiber is thicker or heavier. For example, if the diameter of a polypropylene fiber is 15 microns, it may be squared and the result multiplied by 0.89 grams / cubic centimeter and then multiplied by 0.00707 to convert to denier. That is, a 15 micron polypropylene fiber has a denier of about 1.42. Outside the United States, the unit of measure is more commonly "tex", defined as grams per kilometer of fiber. Tex may be calculated as denier / 9.

As used herein, the term “polymer” generally includes, but is not limited to, homopolymers, such as block, graft, random, and copolymers, such as alternating copolymers, terpolymers, and the like, and And mixtures and modifications thereof. Further, unless otherwise specifically limited, the term "polymer" also includes all possible geometric forms of the material. These forms include, but are not limited to, isotactic, syndiotactic, atactic, and irregular symmetry. As used herein, the term "personal care article" means disposable diapers, training pants, absorbent underwear, adult incontinence products, and feminine hygiene products.

As used herein, the term “bicomponent fiber” refers to a bicomponent fiber formed from at least two polymers that are extruded from separate extruders and spun together to form one fiber. Means the fibers to be made. Bicomponent fibers are also sometimes referred to as bicomponent or multicomponent fibers. The polymer is disposed in individual regions located in a substantially constant relationship across the cross-section of the bicomponent fiber and extends continuously along the length of the bicomponent fiber. Such bicomponent fiber forms may be, for example, a core-sheath arrangement in which one polymer is surrounded by another polymer, or a side-by-side arrangement, a pie arrangement, or an "underwater islands" arrangement. May be. Bicomponent fibers are
U.S. Pat. No. 5,108,820 to Kaneko et al., U.S. Pat. No. 4,795,668 to Kruger et al., And U.S. Pat.
U.S. Pat. No. 5,336,552 to Strac et al.
No. Bicomponent fibers are also taught by US Pat. No. 5,382,400 to Pike et al. For bicomponent fibers, the polymer may be present at 75/25, 50/50, 25/75, or any other desired ratio.

As used herein, the term “machine direction” or “MD” refers to the length of the fabric in the direction in which the fabric is produced.The term “cross-machine direction” or “CD” , Mean the width of the fabric in a direction substantially perpendicular to the MD .. As used herein, the term "consisting essentially of" refers to the target of a given mixture or product. It does not exclude the presence of additional materials that do not significantly affect the properties. Typical materials of this type include, but are not limited to, dyes, antioxidants, stabilizers, surfactants, waxes, glidants, solvents, particles, and additives added to enhance the processability of the mixture. Material to be included.

[0015] The invention disclosed herein is a nonwoven material that does not contain a thermoplastic elastomer or rubber but exhibits elastomeric properties. This material includes a nonwoven web made of bicomponent fibers containing polyester and a second polymer such as polyethylene. When the web is pattern bonded or point bonded and subjected to a heat treatment following bonding, it shrinks and, when stretched up to about 30%, exhibits a non-woven material that exhibits elastic recovery in both the machine and cross directions. Bring. Preferably, the nonwoven web is heated to a temperature of at least about 220 ° F. The amount of stretching and recovery is
It can be adjusted by changing the "shrinkage" temperature and / or the bonding area and / or the polyester content. Further, the amount of shrinkage increases as the basis weight of the nonwoven web increases.

FIG. 1 is a schematic diagram of a process line for producing a stretchable nonwoven material according to the present invention. The process line 10 is prepared for producing a bicomponent continuous filament. The process line 10 includes a pair of extruders 12a and 12b that separately extrude a polymer component A, in this case a polyester, and a polymer component B, such as a polyolefin. Polymer A is fed from a first hopper 14a to a corresponding extruder 12a.
And the polymer component B is supplied from the second hopper 14b to the corresponding extruder 1
2b. Polymer components A and B are sent from extruders 12a and 12b to spinneret 18 through respective polymer conduits 16a and 16b. Spinnerets are known to those skilled in the art and, therefore, will not be described in detail herein. In general, spinneret 18 is overlaid one by one on top of another, with a pattern of openings arranged to create flow paths for separately guiding polymer A and polymer B through the spinneret. A housing containing a spin pack including the plurality of plates. The spinneret 18 has openings arranged in one or more rows. The spinneret opening forms a curtain of filaments extending downward as the polymer is extruded through the spinneret. For purposes of the present invention, spinneret 18 is prepared to form a bicomponent fiber filament such that both polymer A and polymer B are disposed on a portion of the surface of the bicomponent fiber filament. In such a bicomponent filament, one of a side-by-side arrangement, a pie-shaped arrangement, and a polymer forms at least a portion of the lobes spaced apart from each other, and a second polymer has at least its second A polylobal array is included that is centrally located so that a portion of the surface of the polymer can be seen in the area between the lobes.

The process line 10 also includes a quench blower 20 positioned adjacent a filament curtain extending from the spinneret 18. Air from the quench air blower 20 quench the filament extending from the spinneret 18. A fiber extractor or aspirator 22 is located below the spinneret 18 and receives the quenched filament. Fiber extractors or aspirators used for melt spinning of polymers are known to those skilled in the art. Suitable fiber extraction devices for use in this process are linear fiber aspirators of the type shown in U.S. Pat. No. 3,802,817, and U.S. Pat. Nos. 3,692,618 and 3,423. 266, the disclosure of which is incorporated herein by reference.

Generally described, the fiber extraction device 22 includes an elongated vertical passage through which the filament is extracted, through which suction air flows down through the entrance passage from the side of the passage. The heater 24 supplies high-temperature suction air to the fiber extraction device 22. This hot suction air extracts the filaments and environmental air through the fiber extraction device 22. An infinite pore forming surface 26 is disposed below the fiber extraction device 22 and the fiber extraction device 2
A continuous filament is received from the second outlet opening. The forming surface 26 moves around a guide roller 28. A vacuum device 30, located below the forming surface 26 where the filaments are deposited, draws the filament against the forming surface. The process line 10 further includes a compression roller 32 that receives the web with the forefront guide roller 28 as the web is withdrawn from the forming surface 26. in addition,
The process line 10 includes a bonding device 34 such as pattern bonding or thermal point bonding
Further included.

In thermal point bonding, a fiber fabric or web must be passed between a heated calender roll and an anvil roll to bond. The calender rolls are usually, but not always, patterned in some manner so that the entire fabric is not bonded across its entire surface. As a result, various patterns of calendar rolls have been developed for functional as well as aesthetic reasons. One example of a pattern has spots and is about 200% with a combined area of about 30% as taught in US Pat. No. 3,855,046 to Hansen and Pennings.
A Hansen Pennings pattern or "H &P" pattern with bonds per square inch. The H & P pattern has a square point or pin coupling area, each pin having a side dimension of 0.038 inches (0.965 millimeters), a pin spacing of 0.070 inches (1.778 millimeters), and With a bond depth of 0.02
3 inches (0.584 millimeters). The resulting pattern has a combined area of about 29.5%. Another common point bond pattern is the expanded Hansen Pennings bond pattern or "EHP" bond pattern that produces a 15% bond area, where the square pins have a side dimension of 0.037 inch (0.94 mm),
0.097 inch (2.464 mm) pin spacing and 0.039 depth
Inches (0.991 millimeters). Another common point connection pattern, referred to as "714", has a square pin connection area, where each pin has a side dimension of 0.023 inches, a pin spacing of 0.062 inches (1.575 millimeters),
And has a bond depth of 0.033 inches (0.838 millimeters). The resulting pattern has a combined area of about 15%. Yet another common pattern is C-
It is a Star pattern and has a bonding area of about 16.9%. The C-Star pattern has a cross-directional bar or "cordroy" design interrupted by a shooting star. Other common patterns include diamond patterns having diamonds that are slightly offset and repeating, and wire mesh patterns that the name suggests, such as a screen door.

Downstream of the thermal point bonding roller 34 is a hot air knife 36 that heats the web to a target temperature, or other heat treatment such as an oven. Conventional hot air knives include a grooved mandrel that blows a jet of hot air onto the nonwoven web surface. Such hot air knives are taught, for example, in U.S. Pat. No. 4,567,796 to Kloehn et al. Alternatively, the material can be washed, washed to obtain the targeted shrinkage, and dried at an elevated temperature.

As mentioned above, the nonwoven web used to make the nonwoven material of the present invention comprises a plurality of bicomponent fibers containing polyester and a second polymer such as polyethylene. Although any polyester that shrinks when heated may be used, according to one particularly preferred embodiment, the polyester is polyethylene terephthalate. 2
The second polymer containing component fibers is a polymer selected from the group consisting of polyolefins and polyamides. Particularly preferred polyolefins are polyethylene and polypropylene. Suitable polyamides include, but are not limited to, nylon 6, nylon 6/6, nylon 10, and nylon 12.

[0022] Depending on the choice of the polyester and the second polymer used to form the bicomponent fiber, the fiber can be splittable, thereby reducing the softness of the nonwoven material made from the fiber. improves. These fibers can have many mechanical, thermal, or
It can be divided by chemical means. Also, splitting of the bicomponent fibers is not required for shrinkage of the nonwoven web during formation or for restoring the elastomeric properties of the formed nonwoven web, but may increase the elastomeric properties of the material.

According to one preferred embodiment of the present invention, the bicomponent filament comprises polyester (PET) in a range from about 40% to about 90% by weight. According to a particularly preferred embodiment of the invention, the bicomponent filament comprises about 55% by weight of polyester.
To about 65% by weight. The stretch nonwoven material of the present invention according to one embodiment of the present invention comprises a bicomponent filament produced by a bonded carded web process. According to a particularly preferred embodiment, the bicomponent filaments used in the production of the nonwoven web are spunbonded.

EXAMPLE FIG. 2 is a list of data collected for a stretchable nonwoven made according to the method of the present invention. Data are presented for five sample materials made from parallel bicomponent fibers of PET and low linear density polyethylene, with one sample being 1
-5 are assigned. For each sample, two sets of data are presented: mechanical method (MD) elasticity and cross direction (CD) elasticity. The processing conditions for the preparation of these samples are as follows. Polymer: PET = Ticona EKX-183 LLDPE = Dow 6811A HDPE = Dow 25455 Pore size = 0.6 millimeters Throughput = 0.6 ghm Melting temperature = 525 ° F Quenching temperature = 61 ° F Polymer ratio = 50/50 (by volume) Or 59/41 PET / PE (by weight) bonding pattern = see example (5% and 10% helix and HP)

Data for sample 6, a pie-shaped bicomponent nonwoven web that can be split into 16 pieces, is also presented. In this case, the bicomponent fibers were made from PET and high density polyethylene (HDPE). Although the invention has been described and described herein in terms of some preferred embodiments thereof and with numerous details provided for illustrative purposes, additional embodiments are possible for the invention and It will be apparent to those skilled in the art that certain of the details described herein can be varied considerably without departing from the basic principles of the invention.

[Brief description of the drawings]

FIG. 1 is a schematic view of a process line for producing a stretchable nonwoven material according to the present invention.

FIG. 2 is a table showing results obtained from materials produced by the method of the present invention.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) D06C 7/00 (81) Designated country EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, IT, LU, MC, NL, PT, SE), OA (BF, BJ, CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, GM, KE, LS, MW, SD, SL, SZ, TZ, UG, ZW), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM ), AE, AG, AL, AM, AT, AU, AZ, BA, BB, BG, BR, BY, CA, CH, CN, CR, CU, CZ, DE, DK, DM, D , EE, ES, FI, GB, GD, GE, GH, GM, HR, HU, ID, IL, IN, IS, JP, KE, KG, KP, KR, KZ, LC, LK, LR, LS, LT, LU, LV, MA, MD, MG, MK, MN, MW, MX, NO, NZ, PL, PT, RO, RU, SD, SE, SG, SI, SK, SL, TJ, TM, TR , TT, TZ, UA, UG, UZ, VN, YU, ZA, ZW (72) Inventor Nealy James Richard United States Georgia 30202 Alpharetta Waters Kouway 3585 F-term (reference) 3B029 BD10 BD13 3B154 AA07 AA08 AA09 AA17 AB22 BA22 BA60 BB12 DA06 4L047 AA14 AA21 AA23 AA27 AA28 AB02 AB03 AB10 BA08 CB01 CC04 CC05

Claims (23)

[Claims] 1. A nonwoven web having a plurality of bicomponent fibers comprising a polyester and a second polymer, wherein the nonwoven web is selected from the group consisting of pattern bonding, point bonding, and combinations thereof. Characterized by being heated after being bonded by a method as described above. 2. The stretchable nonwoven material according to claim 1, wherein the polyester is a polyester that shrinks when heated. 3. The stretchable nonwoven material according to claim 2, wherein the second polymer is a polymer that shrinks less than the polyester when heated. 4. The stretchable nonwoven material according to claim 2, wherein the polyester is polyethylene terephthalate. 5. The stretch nonwoven fabric of claim 1, wherein the bicomponent fibers are formed such that both the polyester and the second polymer are present on the surface of the fibers. material. 6. The stretchable nonwoven material according to claim 5, wherein the bicomponent fibers are formed as one of a parallel arrangement, a polylobal arrangement, and a pie-shaped arrangement. 7. The stretch nonwoven material of claim 1, wherein the polyester comprises from about 20% to about 90% by weight of the bicomponent fiber. 8. The stretch nonwoven material of claim 1, wherein the polyester comprises from about 40% to about 65% by weight of the bicomponent fiber. 9. The stretchable nonwoven material according to claim 1, wherein the bicomponent fibers are spunbonded. 10. The stretchable nonwoven material according to claim 1, wherein the second polymer is a polymer selected from the group consisting of a polyolefin and a polyamide. 11. The second polymer is polyethylene, polypropylene,
The stretchable nonwoven material of claim 10, wherein the stretchable nonwoven material is selected from the group consisting of: and nylon. 12. The stretchable nonwoven material according to claim 1, wherein the bicomponent fiber is dividable. 13. A method selected from the group consisting of forming a nonwoven web using a plurality of bicomponent fibers comprising a polyester and a second polymer, and pattern bonding, point bonding, and combinations thereof. Bonding the nonwoven web using: and heating the nonwoven web to provide a stretchable nonwoven web. A method of making a stretchable nonwoven material, comprising: 14. The method according to claim 13, wherein said polyester is polyethylene terephthalate. 15. The method of claim 13, wherein said second polymer is a polymer selected from the group consisting of polyolefins and polyamides. 16. The method of claim 13, wherein said bicomponent fibers are spunbonded. 17. The method of claim 13, wherein the polyester comprises from about 20% to about 90% by weight of the bicomponent fiber. 18. The method of claim 13, wherein the polyester comprises from about 40% to about 65% by weight of the bicomponent fiber. 19. The method of claim 13, wherein said bicomponent fibers are formed such that both said polyester and said second polymer are present on the surface of said fibers. 20. The bicomponent fiber according to claim 1, wherein the bicomponent fiber has a parallel arrangement, a polylobal arrangement, and
The method of claim 19, wherein the method is formed as one of a pie-shaped sequence. 21. The method of claim 15, wherein said polyolefin is selected from the group consisting of polyethylene and polypropylene. 22. The method of claim 15, wherein said polyamide is nylon. 23. A nonwoven web having a plurality of bicomponent fibers comprising a polyester and a second polymer, wherein the nonwoven web is selected from the group consisting of pattern bonding, point bonding, and combinations thereof. After being bonded by the method described above, and heated after formation.