Patent Application
20170136502
The present invention generally relates to composite structures and in particular to nonwoven composite structures intended for use in a wipe product.
Across the globe there is great demand for disposable wipe products such as sanitary wipes and facial wipes. In the North American market, the demand is increasing for higher quality products offered at a reasonable price point. The quality attributes most important for consumers of such wipes are softness, absorbency and strength.
Conventional wipes are made of nonwoven material to impart the wipes with specific strength characteristics. However, nonwoven material may be too coarse or may not provide the desired absorbency for the final wipe product. Thus, it is also known to introduce pulp fibers into a nonwoven fabric to increase the overall softness and/or absorbency. Conventional methods of adding pulp to nonwoven material include wet-laying or air-laying pulp fibers directly onto spunbmelt material at speeds less than 150 mpm. Attempts to increase machine speeds result in reduced composite web integrity, excessive fiber (pulp) losses in the waste water stream and/or uneven composite material.
An object of the present invention is to provide a composite product made of a combination of natural fibers and nonwoven materials in which the product has improved structural integrity and bulk properties compared to conventional products.
Another object of the present invention is to provide a process for making a composite product made of a combination of natural fibers and nonwoven materials in which the process involves the use of average line speeds that are greater than 150 mpm. The natural fiber web used in exemplary embodiments of the present invention preferably has very high wet strength, which allows the web to withstand high machine speeds during both unwinding and hydroentangling processes.
Another object of the present invention is to produce a two-layered composite web comprised of one paper layer and one nonwoven web layer, using a protective layer on top of the paper web during the hydro-entangling process. The protective layer assists with the production of a two-layered paper-nonwoven structure at high machine speeds significantly greater than 150 mpm with less injectors (e.g., 4 to 6 injectors during the hydroentangling process) as compared to conventional processes. By way of contrast, conventional processes for making a two-layered paper non-woven structure involve the use of 8 to 10 injectors at low speeds close to 150 mpm.
Another object of the present invention is to provide a wipe product made of a combination of a natural fiber web and spunbond/spunmelt webs.
A composite structure according to an exemplary embodiment of the present invention comprises at least one paper web layer and at least one nonwoven web layer.
In at least one embodiment, the composite structure includes two nonwoven web layers, and the paper web layer is disposed between the two nonwoven web layers.
In at least one embodiment, the at least one nonwoven web layer is a carded web.
In at least one embodiment, the at least one nonwoven web layer is a spunbmelt web.
In at least one embodiment, the at least one nonwoven web layer is a spunmelt web, a meltblown web or a combination thereof
In at least one embodiment, the composite structure is bonded by a hydro entangling process.
In at least one embodiment, the paper web layer is made of hemp fibers.
In at least one embodiment, the paper web layer is a multi-layered web, more preferably a two or more layered web, comprised of both softwood and hardwood pulp fibers.
In at least one embodiment, the paper web layer includes a permanent wet strength additive.
In at least one embodiment, the paper web layer includes a temporary wet strength additive.
In at least one embodiment, fiber used to form the paper web layer is processed to a kappa number less than 100.
In at least one embodiment, at least one nonwoven web layer is a spunbmelt nonwoven web layer.
In at least one embodiment, the paper web layer is made of a structured paper web.
In at least one embodiment, the composite structure is a wipe product.
According to an exemplary embodiment of the present invention, a method for making a composite structure includes: providing at least one paper web layer and at least one nonwoven web layer; and hydroentangling the at least one paper web layer with the at least one nonwoven web layer.
In at least one embodiment, the paper web layer is made of a structured paper web, and the hydroentangling step imparts the structure of the structured paper web to the at least one nonwoven web layer.
In at least one embodiment, the structured paper web layer has the microstructure and the hydroentangling step imparts a macrostructure to the composite material.
In at least one embodiment, the structured paper web layer has both the micro and macrostructures which is then preserved and kept intact in the composite material during hydroentangling step.
The present invention is directed to the use of natural fibers, such as hemp and/or wood fibers, in combination with spunmelt nonwoven to create spunmelt composite materials with natural anti-microbial properties, with specific application as a replacement to typical melt blown and/or absorbent wipes. Fiber processing of the natural fiber (in particular hemp fiber) is a critical factor in producing a uniform carded web and therefore a uniform composite fabric. This fiber processing is measured in terms of kappa number, which relates to the degree of fiber delignification, as measured in accordance with the T236 TAPPI standard. Varying the kappa number results in either an increase or decrease of the hydrophobicity and hydrophilicity of the composite web. For example, a processed hemp fiber with 50 kappa number will be hydrophilic, fine and smooth compared to an unprocessed hemp fiber with 100 kappa number, which will be less hydrophilic, coarse and abrasive.
Wipes made in accordance with the present invention exhibit natural anti-microbial properties without any significant addition of biocides. Further, tweaking the kappa number enables for a range of products from highly absorbent to less absorbent and/or a range of soft to abrasive products.
The internal layer 12 may be either a structured or non-structured natural fiber web. The natural fiber web may be made using carding, airlaid and or wet-laid technologies, and have a basis weight of 10 gsm to 500 gsm. The natural fibers used include any plant fibers, animal fibers and/or wood fibers, and specific examples include abaca, coir, cotton, flax, hemp, jute, ramie, sisal, alpaca wool, angora wool, camel hair, cashmere, mohair, silk, wool, hardwood, softwood, elephant grass fibers, etc. The natural fiber web is chemically or enzymatically processed to a target kappa number less than 100. Processed natural fiber with a lower kappa number is used predominantly in absorbent products such as ADL's, wipes etc., while processed natural fiber with a high kappa number is predominantly in diaper backsheet, diaper cuff, medical markets etc.
The paper web used for the composite structure formation can be a single layer or multilayered structure. The paper web preferably has high temporary and/or permanent wet strength to maintain structural integrity during a subsequent hydro entangling process. Binder solutions may be sprayed onto the paper web before the hydro entangling process to further protect the basesheet structure. Structure can be imparted to the paper web during a separate pre-entangling process by using a structured fabric or on the HE dewatering belt. The structure of the paper web may be varied depending on the through air dried (TAD) fabric used during the paper making process. Structure can also be imparted to the pulp/paper web in a wet laying process by using a structured fabric and then combining the paper web with a spunbond/spunmelt web.
The nonwoven web material layers 14, 16 may be made of spunbond/spunmelt/spunlace fabrics. Nonwoven base materials used may be spunbond, meltblown and the combinations thereof, using any of thermoplastic polymers available, more specifically polyethylene, polypropylene, polyethylene terephthalate (PET) and/or nylon. Nonwoven base materials may be carded and/or spunlace materials including any of the commonly available thermoplastic staple fibers.
The nonwoven composite fabric has a distinct pattern either from the structured natural fiber web, patterning screens used in the hydroentangling process, E-roll designs, or any other suitable patterning technique. Nonwoven composite fabrics produced have a lofty/bulky appearance due to the use of structured natural fiber webs, and have the ability to conform to additional designs due to the discrete fiber length of the natural fibers as opposed to continuous synthetic fibers. In an exemplary embodiment, the nonwoven composite fabric has two-sidedness due to the preferential presence of spunbond and natural fibers on either sides. The nonwoven composite fabric may have anti-microbial properties due to the micro-structure of certain natural fibers.
In at least one embodiment, the nonwoven composite fabric has an MD/CD tensile ratio range of approximately 2.0 to 3.0. The nonwoven composite fabric also has increased absorbency capacity in the range of 400% to 1000%.
Stable and strong composite webs can be produced using combinations of spunmelt and high wet strength paper basesheet. The amount of wet strength of the paper web is one of the critical factors that determines the integrity of the spun bond composite web and the transferability of the pattern from the paper basesheet onto the composite non-woven material. In other words, the amount of wet strength determines the overall strength of the composite material and its ability to retain the TAD structure/pattern from the original paper web.
The amount of hydroentangling (HE) energy used to make the composite web is another critical factor to retain the patterns transferred from the paper web to the overall composite web. Higher HE energies disrupt the pattern and the composite web is smooth and flat, while lower HE energies produce a patterned and bulky composite material.
Micro and/or macro scale patterns may be further incorporated into the composite web by using a structured paper (micro) and/or a 2 or 3-dimensional shell (macro) during the HE process to combine the spunbond/spunmelt web with the paper web. By using low intensity HE energies the patterns of the natural fiber web are preserved and imparted to the composite web.
The structure of the composite web may either be pre-formed during the paper making process or formed on-line using a structured fabric/conveyor web.
In an exemplary embodiment, additional treatments are applied to the nonwoven composite fabric using kiss roll application. For example, softeners are used to further soften the composite materials and the intake of certain water based softening chemistries are significantly higher due to the presence of hydrophilic natural fibers.
The following examples are illustrative of various features and advantages of the present invention:
A patterned/structured paper web was made using a TAD paper machine. The paper web had permanent wet strength Kymene™ 821 (PAE resin) available from Hercules Incorporated, Wilmington, Del., USA, at add-on levels of at least 6 kg/ton. The patterned structure of the paper web was preserved in the composite non-woven fabric by using a low HE energy intensity during the hydroentangling process. HE energy conditions were 20, 40, 40 bars from the three injection manifolds of drum 1 and 40, 40 bars from the two injection manifolds of drum 2, as shown in
Two identical spunbond polypropylene webs with basis weight of 12 gsm each and a 20 gsm paper web used to make paper towel were hydroentangled together to make a composite non-woven fabric.
The patterned/structured paper web was made using a TAD paper machine. The paper web had permanent wet strength Kymene 821 (PAE resin) at add-on levels of at least 6 kg/ton. High HE energy levels was used to entangle the two SB and paper web at 20, 100, 100 bars from the three injection manifolds of drum 1 and 150, 150 bars from the two injection manifolds of drum 2, as shown in
25 gsm hemp carded web was produced using raw unprocessed hemp fibers with fiber lengths ranging from 30 to 60 mm with less than 5% herd content. Then the hemp web was hydroentangled with two identical spunbond webs each at 12 gsm basis weight, as shown in
A three-layer composite web was made on a spunbond/SMS machine (available from Reifenhäuser Reicofil of Troisdorf, Germany) that has an additional hydro-entangling unit and an unwinding unit to unwind paper roll. A 40 gsm three layered paper web produced using a TAD paper machine was unwound between two spunbond beams and subsequently hydro-entangled to make the composite product. The three layered paper web produced using a TAD paper machine was a patterned/structured web. The paper web had permanent wet strength Kymene 821 (PAE resin) at add-on levels of at least 6 kg/Ton. Exxon 3155 polypropylene resin was used to make each of the spunbond layers and the basis weight of each layer was 12.5 gsm. As shown in
A three-layer composite web was made with a 35 gsm paper web sandwiched between two nonwoven webs. One of the nonwoven webs was made of a multilayer, continuous filament, polypropylene nonwoven, weighing 10 gsm, and thermally bonded with a traditional 18% land area, oval bond pattern, coated with surfactant to impart hydrophilicity. The other nonwoven web was made of a multilayer, continuous filament, polypropylene nonwoven, weighing 15 gsm, and lightly thermally bonded with a traditional 18% land area, pillowbond pattern, containing a soft-additive polypropylene resin formulation. The paper web was made using a TAD paper machine. The paper web was made of 3 layers. The flow to each layer of the headbox was about 33% of the total sheet. The three layers of the finished paper web from top to bottom were labeled as air, core and dry. The air layer is the outer layer that is placed on the TAD fabric, the dry layer is the outer layer that is closest to the surface of the Yankee dryer and the core is the center section of the tissue. The tissue was produced with 100% softwood fiber in all layers. Headbox pH was controlled to 7.0 by addition of a caustic to the thick stock before the fan pumps for all samples. Paper web was produced with the addition of permanent wet strength Kymene 821 (PAE resin supplied by Solenis) at add-on levels of at least 6 kg/ton. Also a dry strength additive, Redibond 2038 (Corn Products, 10 Finderne Avenue, Bridgewater, N. J. 08807) at an add-on rate of 1 kg/Ton was added to the core layer. The HE unit shown in
The same process described in Example 5 was used to form a composite web, except that the average line speed was 250 mpm and the HE energy conditions were altered so that pressures were at 200 and 230 from two of the injection manifolds of drum 3.
The same process described in Example 5 was used to form a composite web, except that both nonwoven webs were made of a multilayer, continuous filament, polypropylene nonwoven, weighing 15 gsm, and lightly thermally bonded with a traditional 18% land area, pillowbond pattern, containing a soft-additive polypropylene resin formulation, the average line speed was 150 mpm, the HE energy conditions were altered so that pressures were at 200 and 200 from two of the injection manifolds of drum 3 and a standard 9010P shell (supplied by Andritz of Montbonnot, France) was used on drum 3.
The same process described in Example 7 was used to form a composite web, except that the average line speed was 200 mpm and the 100 MPC shell was used on drum 3.
In all of Examples 5-9, the produced composite web exhibited excellent lamination and structural integrity. Other material properties of the composite webs are provided in Table 1 and were obtained using the following test methods:
Tensile Test Method: WSP 110.4 (05) B with a 100 mm grip distance
Handle-O-Meter: INDA IST 90.3-95 with a 4″×4″ sample size
Absorption Capacity: Test procedure is as follows:
According to another exemplary embodiment of the invention, a two layer composite web is formed with a sacrificial layer or protective screen functioning as a protective layer during the hydroentangling process. For example, as shown in
According to another exemplary embodiment of the invention, the two-layer composite web is produced by unwinding a paper web and a spunmelt web simultaneously into the hydroentangling unit as shown in
The following example relates to the use of a sacrificial layer according to an exemplary embodiment of the present invention:
The same process described in Example 6 was used to a form a composite web, except that one of the nonwoven layers was used as a sacrificial layer during the hydroentangling process. The final composite web product (produced at 250 mpm line speed) had a basis weight of 48.7 gsm, a thickness of 0.49 mm, an absorption capacity of 492%, MD tensile strength of 945 g/cm, CD tensile strength of 376 g/cm and a CD Handle-O-Meter of 25.7 g.
While in the foregoing specification a detailed description of a specific embodiment of the invention was set forth, it will be understood that many of the details herein given may be varied considerably by those skilled in the art without departing from the spirit and scope of the invention.
This application claims priority to U.S. Provisional Patent Application No. 62/254,528, filed Nov. 12, 2015, entitled NONWOVEN COMPOSITE INCLUDING NATURAL FIBER WEB LAYER AND METHOD OF FORMING THE SAME, the contents of which are incorporated herein by reference in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| 62254528 | Nov 2015 | US |
