SOFT ABSORBENT COFORM NONWOVEN WEBS
Various implementations include a fibrous nonwoven web structure having a substantially uniform structure. The nonwoven web includes at least one meltblown fibrous material, at least one secondary fibrous material, and has a TS7 softness value less than about 7.0. In various implementations, the fibrous nonwoven web structure further includes a softening agent.
Nonwoven webs formed as composites of a matrix of meltblown thermoplastic fibrous material and secondary fibrous material, sometimes called coform webs, have been used as an absorbent layer in a wide variety of applications, including absorbent articles, absorbent dry wipes, wet wipes, and mops. However, improvements in the softness and strength properties for coform webs are continually desired. Additionally, there is an on-going need to improve manufacturing efficiency for coform webs, including by reducing material usage and/or waste.
SUMMARYSome of the aspects of the present disclosure relate to a fibrous nonwoven structure including at least one meltblown fibrous material having an average diameter of about 0.5 to 50 μm and at least one secondary fibrous material.
In some aspects, in addition, or in the alternative, to any preceding aspects, a weight ratio of the meltblown fibrous material to the secondary fibrous material is between 10/90 to 60/40.
In some aspects, in addition, or in the alternative, to any preceding aspects, the fibrous nonwoven structure has a TS7 value less than 7.0.
In some aspects, in addition, or in the alternative, to any preceding aspects, the fibrous nonwoven structure further includes a softening agent.
In some aspects, in addition, or in the alternative, to any preceding aspects, the softening agent includes silicone.
In some aspects, in addition, or in the alternative, to any preceding aspects, the fibrous nonwoven structure has a TS7 value of less than about 6.0.
In some aspects, in addition, or in the alternative, to any preceding aspects, the fibrous nonwoven structure has a TS7 value of less than about 5.0.
In some aspects, in addition, or in the alternative, to any preceding aspects, a weight ratio of the softening agent to the secondary fibrous material is in a range of 10 lb/MT to 80 lb/MT.
In some aspects, in addition, or in the alternative, to any preceding aspects, a weight ratio of the softening agent to the secondary fibrous material is in a range of 20 lb/MT to 60 lb/MT.
In some aspects, in addition, or in the alternative, to any preceding aspects, a weight ratio of the softening agent to the secondary fibrous material is 40 lb/MT.
In some aspects, in addition, or in the alternative, to any preceding aspects, the meltblown fibrous material comprises a polymer.
In some aspects, in addition, or in the alternative, to any preceding aspects, the polymer comprises polypropylene.
In some aspects, in addition, or in the alternative, to any preceding aspects, the polymer comprises polyethylene.
In some aspects, in addition, or in the alternative, to any preceding aspects, the secondary fibrous material comprises wood pulp.
In some aspects, in addition, or in the alternative, to any preceding aspects, the weight ratio of the meltblown fibrous material to the secondary fibrous material is in the range of 20/80 to 60/40.
In some aspects, in addition, or in the alternative, to any preceding aspects, the weight ratio of the meltblown fibrous material to the secondary fibrous material is in the range of 25/75 to 40/60.
In some aspects, in addition, or in the alternative, to any preceding aspects, the weight ratio of the meltblown fibrous material to the secondary fibrous material is 30/70.
In some aspects, in addition, or in the alternative, to any preceding aspects, the fibrous nonwoven structure has a flexibility between about 2.5 mm/N and 3.5 mm/N.
In some aspects, in addition, or in the alternative, to any preceding aspects, the fibrous nonwoven structure has a flexibility between about 2.7 mm/N and 3.1 mm/N.
In some aspects, in addition, or in the alternative, to any preceding aspects, the fibrous nonwoven structure has cross-machine direction tensile strength between about 200 gf and 400 gf.
In some aspects, in addition, or in the alternative, to any preceding aspects, the fibrous nonwoven structure has cross-machine direction tensile strength between about 250 gf and 350 gf.
In some aspects, in addition, or in the alternative, to any preceding aspects, the fibrous nonwoven structure has machine-direction tensile strength between about 400 gf and 860 gf.
In some aspects, in addition, or in the alternative, to any preceding aspects, the fibrous nonwoven structure has machine-direction tensile strength between about 400 gf and 550 gf.
Additional aspects of the disclosure will be set forth, in part, in the detailed description, figures, and claims which follow, and in part will be derived from the detailed description or can be learned by practice of the disclosure. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure as disclosed.
Example features and implementations are disclosed in the accompanying drawings. However, the present disclosure is not limited to the precise arrangements and instrumentalities shown.
Reference now will be made in detail to various implementations of the disclosure, one or more examples of which are set forth below. Each example is provided by way of explanation and not limitation. In view of the disclosure, it will be apparent to those skilled in the art that various modifications and variations may be made to the various implementations described herein without departing from the scope or spirit of the disclosure.
As used herein, the term “nonwoven fabric or web” means a web having a structure of individual fibers or threads which are interlaid, but not in a regular or identifiable manner as in a knitted fabric. The term also includes foams and films that have been fibrillated, apertured, or otherwise treated to impart fabric-like properties. Nonwoven fabrics or webs have been formed from many processes such as, for example, meltblowing processes, spunbonding processes, hydroentangled processes, and bonded carded web processes. The basis weight of nonwoven fabrics is usually expressed in ounces of material per square yard (osy) or grams per square meter (gsm), and the fiber diameters are usually expressed in μm.
As used herein, the term “microfibers” means small diameter fibers having an average diameter of not greater than about 75 μm, for example, having an average diameter of from about 0.5 μm to about 50 μm, or more particularly, having an average diameter of from about 2 μm to about 40 μm. Another frequently used expression of fiber diameter is denier, which is defined as grams per 9,000 meters of a fiber and may be calculated as fiber diameter in μm squared, multiplied by the density in grams/cc, multiplied by 0.00707. A lower denier indicates a finer fiber and a higher denier indicates a thicker or heavier fiber. For example, a diameter of a polypropylene fiber given as 15 μm may be converted to denier by squaring, multiplying the result by 0.89 g/cc and multiplying by 0.00707. Thus, a 15 μm polypropylene fiber has a denier of about 1.42 (152×0.89×0.00707=1.415). Outside the United States, the unit of measurement is more commonly the “tex,” which is defined as the grams per kilometer of fiber. Tex may be calculated as denier/9.
As used herein, the term “meltblown fibrous materials” means fibers formed by extruding a molten thermoplastic material through a plurality of fine, usually circular, die capillaries as molten threads or filaments into converging high velocity gas (for example, airstreams) which attenuate the filaments of molten thermoplastic material to reduce their diameter, which may be to microfiber diameter. Thereafter, the meltblown fibrous materials are carried by the high velocity gas stream and are deposited on the forming surface of a collecting surface to form a web of randomly dispersed meltblown fibrous materials. Meltblown fibrous materials are microfibers which may be continuous or discontinuous and are generally smaller than 10 μm in average diameter.
The devices, systems, and methods disclosed herein provide for a nonwoven web material that can be used in various applications, including wet wipe products. In various implementations, the nonwoven web material includes a softening agent, which is added during manufacturing of the web (e.g., by coforming). Among other things, the addition of the softening agent during manufacturing improves the softness properties of the nonwoven web material.
In various implementations, the nonwoven web material may be used as a basesheet in a wet wipe product. Wet wipe products include an absorbent basesheet and a liquid formulation absorbed into the basesheet. The liquid formulation can include various chemicals, such as preservatives and fragrances, which are diluted (e.g., in water). Wet wipe products may be converted via a wet application of the liquid formulation chemistries to the absorbent basesheet. The liquid formulation used in the wet wipe product should remain stable, which can limit the formulation chemistries that are suitable for use in the wet wipe. For example, when a liquid formulation includes a softening agent, the remaining chemistries in the formulation should be selected such that—when mixed with the softening agent—the resulting liquid formulation remains stable.
As disclosed herein, applying functional chemistries (e.g., softening agents) during the basesheet forming process results in several advantages, including improved basesheet softness, improved basesheet retention, and other improved basesheet properties. In certain implementations, when a softening agent is added to the basesheet during the forming process and the basesheet is then used to form a wet wipe product, a wider array of liquid formulations can be added to the basesheet. For example, in certain implementations, the improved softness of the basesheet may enable the liquid formulation to be free of softening agents, which facilitates the use of a wider array of functional chemistries while maintaining stability of the liquid formulation (e.g., chemistries that would otherwise compromise the stability of the liquid formulation if included with a softening agent). Various implementations of the devices, systems, and methods disclosed herein thus provide for a more flexible option for producing wet wipes and other nonwoven web materials with various liquid formulation chemistries, which results in improved consumer-desirable properties in the wet wipe product (e.g., softness, gentleness, and strength). Additionally, as described herein, various implementations provide for more efficient manufacturing of nonwoven web materials, as well as wet wipe products made from the same. As discussed herein, when the nonwoven web is used as a basesheet in a wet wipe product, applying the functional chemistry during the web formation process allows for more flexibility in the liquid formulation used in the wet wipe product (e.g., compared to the application of functional chemistry via a wet application to the formed basesheet during the converting process).
Nonwoven Web StructuresAccording to various implementations, a nonwoven web material combining meltblown fibrous material and secondary fibrous material (also called a “coform web” or “nonwoven coform web”) is disclosed. As discussed in greater detail herein, the nonwoven web material can be manufactured using a coform process in which meltblown fibrous material is mixed with secondary fibrous material. In the mixture, the multiplicity of secondary fibrous materials fibers engage at least some of the meltblown fibrous material fibers to space the meltblown fibers apart. The mixtures are collected in the form of fibrous nonwoven webs, which may be bonded or treated to provide coherent nonwoven materials according to various implementations. These mixtures are referred to as “coform” materials because they are formed by combining two or more materials in the forming step into a single structure. Further details regarding such coform materials and processes are described herein.
During the coforming process, a softening agent is introduced and combined with the mixture of meltblown fibrous material and secondary fibrous material. In various implementations described herein, the softening agent (e.g., silicone) can be introduced into the coform materials at different stages to achieve desired material properties (e.g., softness) and for manufacturing efficiency. As described herein, various implementations of the nonwoven web material having a unique combination of softness and strength properties and can be used to more efficiently manufacture consumer products, such as wet wipes.
Through the methods and apparatuses described with respect to
In the illustrated implementation, the secondary fibrous material fibers 101, meltblown fibrous material fibers 103, and softening agent 105 are substantially evenly dispersed throughout the nonwoven web 100. Accordingly, in the illustrated implementation, the nonwoven web 100 has a substantially uniform structure. In various implementations, the secondary fibrous material fibers 101 may be interconnected by and held captive within the meltblown fibrous material fibers 103 by mechanical entanglement of the meltblown fibrous material fibers 103 with the secondary fibrous material fibers 101, the mechanical entanglement and interconnection of the fibers 101, 103 forming a coherent integrated fiber structure. In various implementations, the coherent integrated fiber structure may be formed by the fibers 101, 103 in combination with the softening agent 105 and without any adhesive, molecular, or hydrogen bonds between the two different types of fibers.
It should be understood that the depiction in
In various implementations of the nonwoven web 100, it may be particularly advantageous for the nonwoven web 100 to have an overall basis weight of between about 20 gsm and about 150 gsm. In more specific implementations, the nonwoven web 100 may have an overall basis weight of between about 50 gsm and about 125 gsm, or between about 40 gsm and about 90 gsm, or between about 50 gsm and about 80 gsm. Such basis weight of the nonwoven web 100 may also vary depending upon the desired end use of the nonwoven web 100. For example, a suitable fibrous nonwoven web structure for wiping the skin may define a basis weight of from about 30 to about 80 gsm and desirably about 45 to 70 gsm. The basis weight (in grams per square meter, g/m2 or gsm) is calculated by dividing the dry weight (in grams) by the area (in square meters).
In various implementations, the relative percentages of the meltblown fibrous material and secondary fibrous material in the nonwoven web 100 can vary over a wide range depending on the desired characteristics of the nonwoven web 100. For example, the nonwoven web 100 can have from about 20 to 60 weight percent of meltblown fibrous material and from about 40 to 80 weight percent of secondary fibrous material. In certain implementations, the weight ratio of meltblown fibrous material to secondary fibrous material can be from about 20/80 to about 60/40. In more particular implementations, the weight ratio of meltblown fibrous material to secondary fibrous material can be from 25/75 to about 40/60. In some implementations, the weight ratio of meltblown fibrous material to secondary fibrous material is 30/70.
In various implementations, a weight ratio of the softening agent to the secondary fibrous material is in a range of 5 lb/MT to 100 lb/MT. In some implementations, a weight ratio of the softening agent to the secondary fibrous material is in a range of 10 lb/MT to 80 lb/MT. In some implementations, a weight ratio of the softening agent to the secondary fibrous material is in a range of 20 lb/MT to 60 lb/MT. In some implementations, a weight ratio of the softening agent to the secondary fibrous material is in a range of 20 lb/MT to 50 lb/MT. In some implementations, a weight ratio of the softening agent to the secondary fibrous material is in a range of 20 lb/MT to 40 lb/MT. In some implementations, a weight ratio of the softening agent to the secondary fibrous material is in a range of 30 lb/MT to 40 lb/MT. In some implementations, the weight ratio of the softening agent to the meltblown fibrous material and the secondary fibrous material is 40 lb/MT.
In some implementations, the nonwoven web 100 has a TS7 value (indicative of softness) of less than 7.0. In some implementations, the nonwoven web has a TS7 value of less than 6.0. In some implementations, the nonwoven web has a TS7 value of less than 5.0. In some implementations, the nonwoven web has a TS7 value between about 7.0 and about 3.0. In some implementations, the nonwoven web has a TS7 value between about 6.0 and about 3.0. In some implementations, the nonwoven web has a TS7 value between about 6.0 and about 4.0. In some implementations, the nonwoven web has a TS7 value between about 5.5 and about 4.0.
In some implementations, the nonwoven web 100 has a flexibility between about 2.5 mm/N and 3.5 mm/N. In some implementations, the nonwoven web 100 has a flexibility between about 2.7 mm/N and 3.1 mm/N. In some implementations, the nonwoven web 100 has a flexibility between 1.0 mm/N and 5 mm/N.
In some implementations, the nonwoven web 100 has a machine direction tensile strength (MDT) between about 400 gf and about 860 gf. In some implementations, the nonwoven web 100 has an MDT strength between about 450 gf and about 700 gf. In some implementations, the nonwoven web 100 has an MDT strength between about 400 gf and about 550 gf.
In some implementations, the nonwoven web 100 has a cross-machine direction tensile strength (CDT) between about 150 gf and about 500 gf. In some implementations, the nonwoven web 100 has a CDT strength between about 200 gf and about 400 gf. In some implementations, the nonwoven web 100 has a CDT strength between about 250 gf and about 350 gf.
Meltblown Fibrous MaterialMeltblown fibrous materials suitable for forming the fibers 103 in the nonwoven web 100 include polyolefins (e.g., polyethylene, polypropylene, polybutylene and the like), polyamides, olefin copolymers, and polyesters. In some implementations, the meltblown fibrous material fibers 103 in the nonwoven web 100 are polypropylene. In some implementations, the meltblown fibrous material used for forming the meltblown fibers 103 is a high melt flow rate metallocene-based polypropylene homopolymer (e.g., Metocene MF650X manufactured by LyondellBassell; Achieve™ Advanced PP6945G1 manufactured by ExxonMobil). In various implementations, the meltblown fibrous material fibers 103 may have an average diameter of about 0.5 to 40 μm.
In certain implementations, the nonwoven web 100 can include meltblown fibers 103 comprising a first polymer component and a second polymer component (“bicomponent fibers” herein, also called multicomponent fibers) or meltblown fibers comprising a homopolymer (“homogenous fibers” herein, also called monocomponent fibers). Although the term “bicomponent fibers” is used herein, it should not be understood to be limiting such fibers to comprising only two polymer components. Rather, such bicomponent fibers as used herein comprise at least two polymer components, but may comprise additional polymer components. The bicomponent meltblown fibers and the homogenous meltblown fibers may be combined in a layered manner, along with secondary fibrous material, to produce a layered coform structure.
Secondary Fibrous MaterialSecondary fibrous materials suitable or forming the fibers 101 in the nonwoven web 100 may be selected from the group including one or more polyester fibers, polyamide fibers, cellulosic derived fibers such as, for example, rayon fibers and wood pulp fibers, multi-component fibers such as, for example, sheath-core multi-component fibers, natural fibers such as silk fibers, wool fibers or cotton fibers or electrically conductive fibers or blends of two or more of such secondary fibrous materials. Other types of secondary fibrous materials such as, for example, polyethylene fibers and polypropylene fibers, as well as blends of two or more of other types of secondary fibrous materials may be used. The secondary fibrous materials may be microfibers or the secondary fibrous materials may be macrofibers having an average diameter of from about 300 μm to about 1,000 μm.
In at least some implementations, the secondary fibrous material forming the fibers 101 of the nonwoven web 100 may be absorbent fibers. As one example, such absorbent fibers may be pulp fibers formed by a variety of pulping processes, such as kraft pulp, sulfite pulp, thermomechanical pulp, etc. In certain implementations, wood pulp fibers are suitable for use as a secondary fibrous material and advantageous due to low cost, high absorbency, and retention of satisfactory tactile properties. The pulp fibers may include softwood fibers having an average fiber length of greater than 1 mm and particularly from about 2 to 5 mm based on a length-weighted average. Such softwood fibers can include, but are not limited to, northern softwood, southern softwood, redwood, red cedar, hemlock, pine (e.g., southern pines), spruce (e.g., black spruce), combinations thereof, and so forth. In some implementations, the secondary fibrous material used for forming the secondary fibrous material fibers 101 is a rolled, ECF-bleached, southern pine, softwood kraft fluff pulp treated with debonder and antistatic agent(s) (medically and FDA-approved, and BfR compliant) (e.g., available from Georgia-Pacific or International Paper).
In some implementations, hardwood fibers, such as eucalyptus, maple, birch, aspen, and so forth, can also be used. In certain instances, eucalyptus fibers may be particularly desired to increase the softness of the web. Eucalyptus fibers can also enhance the brightness, increase the opacity, and change the pore structure of the web to increase its wicking ability. Moreover, if desired, secondary fibers obtained from recycled materials may be used, such as fiber pulp from sources such as, for example, newsprint, reclaimed paperboard, and office waste. Further, other natural fibers can also be used in the present invention, such as abaca, sabai grass, milkweed floss, pineapple leaf, and so forth. In addition, in some instances, synthetic fibers can also be used.
Further absorbent material may be used in conjunction with pulp fibers, such as superabsorbent that is in the form fibers, particles, gels, etc. Generally, superabsorbents are water-swellable materials capable of absorbing at least about 20 times its weight and, in some cases, at least about 30 times its weight in an aqueous solution containing 0.9 weight percent sodium chloride. The superabsorbent may be formed from natural, synthetic and modified natural polymers and materials. Examples of synthetic superabsorbent polymers include the alkali metal and ammonium salts of poly(acrylic acid) and poly(methacrylic acid), poly(acrylamides), poly(vinyl ethers), maleic anhydride copolymers with vinyl ethers and alpha-olefins, poly(vinyl pyrrolidone), poly(vinylmorpholinone), poly(vinyl alcohol), and mixtures and copolymers thereof. Further, superabsorbents include natural and modified natural polymers, such as hydrolyzed acrylonitrile-grafted starch, acrylic acid grafted starch, methyl cellulose, chitosan, carboxymethyl cellulose, hydroxypropyl cellulose, and the natural gums, such as alginates, xanthan gum, locust bean gum and so forth. Mixtures of natural and wholly or partially synthetic superabsorbent polymers may also be useful in the present invention.
Softening AgentSoftening agents suitable for use in the nonwoven web 100 include, for example, silicone (e.g., silicone diluted in water). In some implementations, the softening agent includes a non-ionic microemulsion of a functional silicone fluid, such as WACKER HC 3502 available from Wacker Chemie AG (34% active silicone by weight) or Shin-Etsu KF-889s. In some implementations, the softening agent is transparent or translucent. In some implementations, the ratio of silicone to water in the softening agent is in the range of 10/90 to 50/50. In some implementations, the ratio of silicone to water in the softening agent is about 34/66 by weight.
Systems and Methods of Manufacturing Nonwoven Web StructuresThe coform nonwoven web 100 is generally made by a process in which at least one meltblowing die (e.g., two) is arranged near a chute through which the absorbent material is added while the web forms. Some examples of such coform techniques are disclosed in U.S. Pat. No. 4,100,324 to Anderson, et al.; U.S. Pat. No. 5,350,624 to Georger, et al.; and U.S. Pat. No. 5,508,102 to Georger, et al., as well as U.S. Patent Application Publication Nos. 2003/0200991 to Keck, et al. and 2007/0049153 to Dunbar, et al., all of which are incorporated herein in their entirety by reference thereto for all purposes.
In various implementations, a method of manufacturing a nonwoven web structure is disclosed that provides for a spray application of functional chemistry during the nonwoven web formation process. The applied functional chemistry may include, but is not limited to, one or more softening agents. In various implementations, a spray system is used to apply functional chemistry directly in the web forming process to provide for even distribution and mixing of the functional chemistry with the web's meltblown fibrous material fibers and secondary fibrous material fibers. Process air streams can be used to allow for the sprayed functional chemistry to be adequately retained within the web during formation and provide a substantially uniform structure.
According to various implementations, the method for manufacturing the nonwoven web generally includes providing a stream of meltblown fibrous material, providing a stream of a secondary fibrous material, providing a stream of softening agent, and merging the stream of meltblown fibrous material, the stream of the secondary fibrous material, and the stream of softening agent to form a composite stream. The composite stream is then deposited onto a forming surface to cause the composite stream to form a nonwoven web having a substantially uniform structure.
As discussed herein, in certain implementations, the stream of secondary fibrous material and the stream of softening agent are merged to form a combined stream. The combined stream (of secondary fibrous material and softening agent) is then merged with the stream of meltblown fibrous material to form the composite stream. In other implementations, the stream of secondary fibrous material and the stream of meltblown fibrous material are merged to form a combined stream, and the combined stream (of secondary fibrous material and meltblown fibrous material) is then merged with the stream of softening agent to form the composite stream.
According to various other implementations, the method for manufacturing the nonwoven web generally includes providing a mat of secondary fibrous material treated with a softening agent and picking the mat to form a combined stream of the secondary fibrous material and softening agent. The method further includes providing a stream of meltblown fibrous material, and merging the stream of meltblown fibrous material with the combined stream (of secondary fibrous material and softening agent) to form a composite stream. The composite stream is then deposited onto a forming surface to cause the composite stream to form a nonwoven web having a substantially uniform structure.
The sheets or mats 240 of secondary fibrous material are fed to the picker roll 236 by a roller arrangement 242. After the teeth 238 of the picker roll 236 have separated the sheet or mat 240 of secondary fibrous material into individual secondary fibrous materials 232, the individual secondary fibrous materials 232 (e.g., the secondary fibrous material fibers 101) are directed through a nozzle 244 to form a stream 234 of secondary fibrous material 232.
A housing 246 encloses the picker roll 236 and provides a passageway or gap between the housing 246 and the surface of the teeth 238 of the picker roll 236. A dilution gas, for example, air, is supplied by a dilution air fan 272 to the passageway or gap between the surface of the picker roll 236 and the housing 246 by way of a gas duct 250. The gas is supplied in sufficient quantity to serve as a medium for conveying the secondary fibrous materials 232 through the nozzle 244, thereby forming the secondary fibrous material stream 234.
In some implementations, dual circular manifolds are used as a dilution air fan 272 providing uniform air distribution that delivers air into the gas duct 250. The dilution air provided by the dual circular manifolds delivers pulp fibers uniformly to a formation zone 230 above a formation surface 258, such as a belt or wire, which is discussed further herein.
A separate stripper air fan 274 is used to provide a secondary stripper airflow entering the system at a junction 252 to help remove the secondary fibrous material 232 from the teeth 238 of the picker roll 236. Separate dilution air fans 272 and stripper air fans 274 are used to allow for operators to balance the stripper air flow allowing for optimum fiber release off of the teeth 238 and an increase in the flowrate of the secondary fibrous material stream 234.
In various implementations, the second fibrous material stream 234 is conveyed through the nozzle 244 at about the velocity at which the individual secondary fibrous materials 232 leave the teeth 238 of the picker roll 236. In other words, the secondary fibrous materials 232, upon leaving the teeth 238 of the picker roll 236 and entering the nozzle 244, generally maintain their velocity in both magnitude and direction from the point where they left the teeth 238 of the picker roll 236. Such an arrangement is discussed in more detail in U.S. Pat. No. 4,100,324 to Anderson, et al.
As shown in
In certain implementations, the softening agent manifold's one or more openings 292 each have a diameter between about 0.01 inches and 0.05 inches. In one implementation, the softening agent manifold's one or more openings 292 are each have a diameter of 0.02 inches. In various implementations, the softening agent manifold's one or more openings 292 comprise a plurality of openings 292. In certain implementations, the plurality of openings 292 are aligned in a row along the length of the softening agent manifold 290 and evenly spaced from one another. In various implementations, the softening agent manifold's openings 292 are each spaced between 0.5 inches and 2.0 inches from one other. In one implementation, the softening agent manifold's openings 292 are each spaced one inch apart from each other (e.g., such that the softening agent manifold 290 includes one opening 292 per inch along its length). In another implementation, the softening agent manifold's openings 292 are each spaced two inches apart from each other (e.g., such that the softening agent manifold 290 includes between one opening 292 per two inches along its length). In one implementation, the softening agent manifold includes twelve openings 292, each having a diameter of 0.02 inches and each spaced one inch apart from one other in a linear row.
In other implementations, the softening agent manifold's openings 292 may each comprise a spray nozzle secured to the manifold 290. For example, in one implementation, the softening agent manifold's openings 292 comprise four flat spray nozzles. Each spray nozzle has, for example, an orifice diameter of 0.02 inches (e.g, a McMaster-Carr No-Drip Flat Spray Nozzle, part number 4846T112). The four spray nozzles 292 are evenly spaced apart from one another (e.g., 3 inches apart from one another along the length of the softening agent manifold 290).
As shown in
As further depicted in
In various implementations, the angle of the one or more softening agent streams 294 relative to the secondary fibrous material stream 234 is selected to facilitate merger of the streams. For example, in the illustrated implementation of
In various implementations, the velocity and flowrate of the one or more softening agent streams 294, along with the angle of the one or more softening agent streams 294 relative to the secondary fibrous material stream 234, are configured to fully merge the softening agent with the secondary fibrous material 232 such that the softening agent is dispersed substantially evenly throughout the nonwoven web material. In certain implementations, the flow rate of the one or more softening agent streams 294 (collectively through the softening agent manifold 230) is between about 250 ml/min to 1000 ml/min. In certain implementations, the flow rate of the one or more softening agent streams 294 (collectively through the softening agent manifold 230) is between about 400 ml/min and 600 ml/min. In one implementation, the flow rate of the one or more softening agent streams 294 (collectively through the softening agent manifold 230) is 425 ml/min. In another implementation, the flow rate of the one or more softening agent streams 294 (collectively through the softening agent manifold 230) is 600 ml/min.
The apparatus 200 further includes a first meltblowing die 216 and a second meltblowing die 218, which are oriented such that they oppose one another. Each meltblowing die 216, 218 is associated with a pellet hopper 212, 212′ and extruder 214, 214′. Pellets or chips, etc. (not shown) of a thermoplastic polymer are introduced into each pellet hopper 212, 212′ to feed into the meltblowing dies 216, 218. The extruder 214 has an extrusion screw (not shown) which is driven by a conventional drive motor (not shown). As the polymer advances through the extruder 214, due to rotation of the extrusion screw by the drive motor, it is progressively heated to a molten state. Heating the thermoplastic polymer to the molten state may be accomplished in a plurality of discrete steps with its temperature being gradually elevated as it advances through discrete heating zones of the extruder 214 toward the two meltblowing dies 216 and 218, respectively. The meltblowing dies 216, 218 may be yet another heating zone where the temperature of the thermoplastic resin is maintained at an elevated level for extrusion.
In the illustrated implantation of
The combined stream 235 of secondary fibrous materials 232 and softening agent is merged with the two meltblown fibrous material streams 226, 228 of meltblown fibrous material 220 (e.g., thermoplastic polymer fibers or microfibers) at the formation zone 230 to form a composite stream 256. In various implementations, the fibers (e.g., microfibers) of the meltblown fibrous material streams 226, 228 are in a soft nascent condition at an elevated temperature when they are turbulently mixed with the secondary fibrous materials 232 and softening agent in air within the formation zone 230. Merging of the combined stream 235 into the two meltblown fibrous material streams 226, 228 is designed to produce a distribution of secondary fibrous materials 232 and softening agent within the combined meltblown fibrous material streams 226, 228 of meltblown fibrous material 220. As shown in
In various implementations, meltblown fibrous material streams 226, 228 containing meltblown fibrous material 200 (e.g., thermoplastic polymer fibers) are aligned to converge at the formation zone 230 (also referred to as an impingement zone). Typically, the meltblowing dies 216, 218 are arranged at a certain angle with respect to the forming surface 258, such as described in U.S. Pat. Nos. 5,508,102 and 5,350,624 to Georger et al.
Utilization of the meltblowing dies 216, 218 as described in various implementations herein allow for improved formation and softness characteristics. The meltblowing dies 216, 218 are mounted so they each can be set at an angle θ. As shown in
As shown in
The distance from the formation zone 230 to the tip of each meltblowing die 216, 218 (i.e., distance X) should generally be set to minimize dispersion of each meltblown fibrous material stream 226, 228. For example, in various implementations, the distance X may range up to about 41 cm (16 in). In certain implementations, this distance should be greater than 6 cm (2.5 in). For example, for distances X in the range of about 6 cm (2.5 in) to 16 cm (6 in), the distance from the tip of each meltblowing die 216, 218 to the formation zone 230 can be determined from the separation between the die tips a and the die angle θ utilizing the formula:
Generally, the dispersion of the composite stream 256 may be minimized by selecting a proper vertical forming distance (i.e., distance β) before the composite stream 256 contacts the forming surface 258. β is the distance from the tips of the meltblowing dies 216, 218 (e.g., at the offices 224 of the dies) to the forming surface 258. In various implementations, a shorter vertical forming distance is generally desirable for minimizing dispersion. This is balanced by the need for the extruded fibers to solidify from their tacky, semi-molten state before contacting the forming surface 258. For example, in various implementations, the vertical forming distance β may range from about 7 cm (3 in) to about 38 cm (15 in) from the meltblowing die tip. Desirably, in certain implementations, this vertical distance β may be about 10 cm (4 in) to about 28 cm (11 in) from the meltblowing die tip.
An important component of the vertical forming distance β is the distance between the formation zone 230 and the forming surface 258 (i.e., distance Y). In various implementations, the formation zone 230 is located so that the composite stream 256 has only a minimum distance (Y) to travel to reach the forming surface 258 to minimize dispersion of the entrained secondary fibrous material fibers and meltblown fibrous material fibers. For example, in various implementations, the distance (Y) from the formation zone to the forming surface may range up to about 31 cm (12 in). Desirably, in certain implementations, the distance (Y) from the formation zone 230 to the forming surface 258 may range from about 5 cm (3 in) to about 18 cm (7 in) inches. The distance from the formation zone 230 to the forming surface 258 can be determined from the vertical forming distance β, the separation between the die tips (α) and the die angle (θ) utilizing the formula:
As discussed with respect to
In certain implementations, it may be desirable to cool the secondary fibrous material stream 234. For example, cooling the secondary fibrous material stream 234 could accelerate the quenching of the molten or tacky meltblown fibrous materials and provide for shorter distances between the meltblowing die tip and the forming surface 258 which could be used to minimize fiber dispersion. In some implementations, the temperature of the secondary fibrous material stream 234 may be cooled to about 65 to about 85 degrees Fahrenheit.
By balancing the meltblown fibrous material streams 226, 228 and the combined stream 235, the desired die angles θ of the meltblowing dies 216, 218, the vertical forming distance (β), the distance between the meltblowing die tips (α), the distance between the formation zone 230 and the meltblowing die tips (X), and the distance between the formation zone 230 and the forming surface 258 (Y), it is possible to provide a controlled integration of secondary fibrous materials 232 and softening agent within the meltblown fibrous material streams 226, 228.
Referring back to
Deposition of the fibers in the composite stream 256 is aided by an under-wire vacuum supplied by a negative air pressure unit, or below-wire-exhaust system, 280. The illustrated below-wire-exhaust system has an increased number of zones, providing three zones in the machine direction unlike conventional machines. For example, the first zone 282 sits upstream in the machine direction of the formation zone 230, the second zone 284 is directly below the pump nozzle and formation zone 230, and the third zone 286 is downstream in the machine direction of the formation zone 230. In various implementations, the second zone 284 has the highest airflow, the first zone 282 has the smallest amount of air flow, and the third zone 286 has higher airflow than the first zone 282, but less than the second zone 284. In other implementations, the zones 284, 282, 286 may also supply the same amount of airflow if found to be optimal. The zoned below-wire-exhaust system 280 provides increased airflow where needed and better control of forming zone air management, resulting in improved formation and uniformity.
The fibrous nonwoven web structure 254 is coherent and may be removed from the forming surface 258 as a self-supporting nonwoven material. In various implementations, the nonwoven web 254 has adequate strength and integrity to be used without any post-treatments such as pattern bonding and the like. In certain implementations, a pair of pinch rollers or pattern bonding rollers may be used to bond portions of the material.
According to the above-described apparatus 200 and associated process, the secondary fibrous materials 232 become interconnected by and held captive within the meltblown fibrous material 220 by mechanical entanglement of the thermoplastic polymer fibers with the secondary fibrous materials. The mechanical entanglement and interconnection of the polymer fibers and secondary fibrous materials alone are able to form a coherent integrated fiber structure (e.g., coform nonwoven web structure 254). The coherent integrated fiber structure may be formed by the polymer fibers and secondary fibrous materials without any adhesive or molecular or hydrogen bonds between the two different types of fibers. Furthermore, as a result of the process as implemented on the apparatus 200, the softening agent is substantially evenly dispersed through the coform nonwoven web structure 254, thereby enhancing various properties of the nonwoven web 254 (e.g., softness).
As in the apparatus 200 of
As in the apparatus 200 of
As shown in
Furthermore, as in the apparatus 200, the softening agent manifold 290 in the apparatus 400 is positioned adjacent to the second meltblowing die 218 and opposite from the first meltblowing die 216. Accordingly, in the apparatus 400, the softening agent stream 294 emitted from the softening agent manifold 290 merges with the combined stream 235 on a side of the combined stream 235 that is downstream relative to the machine direction of the forming surface 258 (i.e., the side of the combined stream 235 adjacent to the second meltblowing die 218).
As in the apparatus 400 of
As in the apparatus 200 of
Although the apparatus 600 shown in
In some implementations, it is desirable to feed into the picker roll 236 at least one additional mat of secondary fibrous material along with the mat 240 of secondary fibrous material. In such implementations, the mats of secondary fibrous material are stacked in layers and enter the picker roll at the same time. This can be advantageous in implementations, like those discussed above, in which the softening agent is included in the mat 240 of secondary fibrous material. In some instances, the use of at least one additional untreated mat of secondary fibrous material (e.g., without softening agent added) between the picker roll 236 and the treated mat of secondary fibrous material can reduce the likelihood that the mat 240 will stick to the teeth 238 of the picker roll 236. In such implementations, a treated mat of secondary fibrous material (e.g., treated with a softening agent) is disposed on an untreated mat of secondary fibrous material (e.g., where the untreated mat is not treated with the softening agent). The treated mat of secondary fibrous material and the untreated mat of secondary fibrous material are then fed into the picker roll 236. As the mat of secondary fibrous material that has been treated with the softening agent is covered on one side by the untreated mat, the treated mat of secondary fibrous material is less likely to stick to the picker roll's teeth 238. The plurality of teeth 238 of the picker roll 236 separate the untreated mat of secondary fibrous material and the treated mat of secondary fibrous material into a stream of individual secondary fibrous materials 232 mixed with the softening agent to form a combined stream 235. The combined stream 235 of secondary fibrous materials and softening agent flows through the nozzle 244 and merges with the meltblown fibrous material streams 226, 228 in the formation zone 230 to form a composite stream 256 (e.g., similar to the apparatus 200 shown in
In certain implementations, two additional untreated mats of secondary fibrous material are included with the treated mat of secondary fibrous material. In such implementations, a treated mat of secondary fibrous material (e.g., treated with a softening agent) is disposed between a first untreated mat of secondary fibrous material and a second untreated mat of secondary fibrous material (e.g., where the first and second untreated mats are not treated with the softening agent). The first untreated mat of secondary fibrous material, the treated mat of secondary fibrous material, and the second untreated mat of secondary fibrous material are then fed into the picker roll 236. As the mat of secondary fibrous material that has been treated with the softening agent is covered on both surfaces by untreated mats, the teeth 238 of the picker roll 236 first contacts the untreated mats to reduce the likelihood that the treated mat of secondary fibrous material sticks to the picker roll's teeth 238. The plurality of teeth 238 of the picker roll 236 separate the first untreated mat of secondary fibrous material, the treated mat of secondary fibrous material, and the second untreated mat of secondary fibrous material into a stream of individual secondary fibrous materials 232 mixed with the softening agent to form a combined stream 235. The combined stream 235 of secondary fibrous materials and softening agent flows through the nozzle 244 and merges with the meltblown fibrous material streams 226, 228 in the formation zone 230 to form a composite stream 256 (e.g., similar to the apparatus 200 shown in
As in the apparatus 200 of
Furthermore, the softening agent manifold 290 of the apparatus 700 is oriented such that the softening agent stream 294 merges with the second meltblown fibrous material stream 228 above the formation zone 230. Thus, in the apparatus 700, the second meltblown fibrous material stream 228 and softening agent stream 294 merge to form a combined stream 235 (comprised of meltblown fibrous material stream 220 and softening agent). The combined stream 235 then merges with the secondary fibrous material stream 234 and the first meltblown fibrous material stream 226 at the formation zone 230 to form the composite stream 256 (comprised of secondary fibrous material 232, meltblown fibrous material 220, and softening agent). The composite stream 256 is then deposited onto the forming surface 258 of the collection device to form a nonwoven web 254 (e.g., in the manner described with respect to the apparatus 200 of
Furthermore, as shown in
As in the apparatus 700 of
As shown in
It should be understood that the present disclosure is by no means limited to the above-described implementations. In an alternative implementation, for example, first and second meltblowing dies may be employed that extend substantially across a forming surface in a direction that is substantially transverse to the direction of movement of the forming surface. The die heads may likewise be arranged in a substantially vertical disposition, i.e., perpendicular to the forming surface, so that the thus-produced meltblown fibers are blown directly down onto the forming surface. Such a configuration is well known in the art and described in more detail in, for instance, U.S. Patent Application Publication No. 2007/0049153 to Dunbar, et al., which is incorporated herein in its entirety by reference thereto for all purposes. Furthermore, although the above-described implementations employ multiple meltblowing die heads to produce fibers of differing sizes, a single die head may also be employed. An example of such a process is described, for instance, in U.S. Pat. No. 7,168,932 to Lassig, et al., which is incorporated herein in its entirety by reference thereto for all purposes.
Example Nonwoven WebsVarious nonwoven webs were formed according to aspects of the present disclosure and tested to determine particular web properties, including softness, strength, and flexibility.
A first group of example nonwoven webs (PSD-10 and PSD-40) were formed using the apparatus 200 described with respect to
The web examples PSD-10, PSD-40, and Control 1 were formed having a total basis weight of 70 gsm. The secondary fibrous material used was pulp mats supplied by International Paper (rolled, ECF-bleached, southern pine, softwood kraft fluff pulp treated with debonder and antistatic agent(s), medically and FDA-approved, and BfR compliant) and comprised approximately 70% by weight of each example nonwoven web (i.e., 49 gsm). The meltblown fibrous material used was a high melt flow rate metallocene-based polypropylene homopolymer (Achieve™ Advanced PP6945G1 manufactured by ExxonMobil) and comprised approximately 30% by weight of each example nonwoven web (i.e., 21 gsm). The softening agent used was silicone (WACKER HC 3502) and was provided in different amounts in each example nonwoven web (from about 0.000-0.315 gsm, or 0 to 40 lbs/MT pulp). The softening agent manifold used included twelve openings, each having a diameter of 0.02 inches and each spaced 1.0 inch apart from each other in a linear row. Particular characteristics of the example webs PSD-10, PSD-40, and Control 1 are shown below in TABLE 1.
TABLE 2 reports on performance properties of the example nonwoven webs PSD-10, PSD-40, and Control 1. More specifically, the example nonwoven webs PSD-10, PSD-40, and Control 1 were tested for strength according to the CDT and MDT Strength Test Methods described herein and for softness and flexibility according to the EMTEC TSA Softness and Flexibility Test Methods described herein.
A second group of example nonwoven webs (PSU-2.5, PSU-5, PSU-10, PSU-20, PSU-40, PSU-80) were formed using the apparatus 300 described with respect to
The examples PSU-2.5, PSU-5, PSU-10, PSU-20, PSU-40, PSU-80, and Control 2 were formed having a total basis weight of 70 gsm. The secondary fibrous material used was pulp mats supplied by Georgia-Pacific (rolled, ECF-bleached, southern pine, softwood kraft fluff pulp treated with debonder and antistatic agent(s), medically and FDA-approved, and BfR compliant) and comprised approximately 70% by weight of each example nonwoven web (i.e., 49 gsm). The meltblown fibrous material used was a high melt flow rate metallocene-based polypropylene homopolymer (Metocene MF650X manufactured by LyondellBassell) and comprised approximately 30% by weight of each example nonwoven web (i.e., 21 gsm). The softening agent used was silicone (WACKER HC 3502) and was provided in different amounts in each example nonwoven web (from about 0.000-0.605 gsm, or 0 to 80 lbs/MT pulp). The softening agent manifold used included twelve openings, each having a diameter of 0.02 inches and each spaced 1.0 inch apart from each other in a linear row. Particular characteristics of the example webs PSU-2.5, PSU-5, PSU-10, PSU-20, PSU-40, PSU-80, and Control 2 are shown below in TABLE 3.
TABLE 4 reports on performance properties of the example nonwoven webs PSU-2.5, PSU-5, PSU-10, PSU-20, PSU-40, PSU-80, and Control 2. More specifically, the example nonwoven webs PSU-2.5, PSU-5, PSU-10, PSU-20, PSU-40, PSU-80, and Control 2 were tested for strength according to the CDT and MDT Strength Test Methods described herein and for softness and flexibility according to the EMTEC TSA Softness and Flexibility Test Methods described herein.
A third group of example nonwoven webs (MSD-10, MSD-20, MSD-40) were formed using the apparatus 700 described with respect to
The examples MSD-10, MSD-20, MSD-40, and Control 2 were formed having a total basis weight of 70 gsm. The secondary fibrous material used was pulp mats supplied by Georgia-Pacific (rolled, ECF-bleached, southern pine, softwood kraft fluff pulp treated with debonder and antistatic agent(s), medically and FDA-approved, and BfR compliant) and comprised approximately 70% by weight of each example nonwoven web (i.e., 49 gsm). The meltblown fibrous material used was a high melt flow rate metallocene-based polypropylene homopolymer (Metocene MF650X manufactured by LyondellBassell) and comprised approximately 30% by weight of each example nonwoven web (i.e., 21 gsm). The softening agent used was silicone (WACKER HC 3502) and was provided in different amounts in each example nonwoven web (from about 0.000-0.302 gsm, or 0 to 40 lbs/MT pulp). The softening agent manifold used included twelve openings, each having a diameter of 0.02 inches and each spaced 1.0 inch apart from each other in a linear row. Particular characteristics of the example webs MSD-10, MSD-20, MSD-40, and Control 2 are shown below in TABLE 5.
TABLE 6 reports on performance properties of the example nonwoven webs MSD-10, MSD-20, MSD-40, and Control 2. More specifically, the example nonwoven webs MSD-10, MSD-20, MSD-40, and Control 2 were tested for strength according to the CDT and MDT Strength Test Methods described herein and for softness and flexibility according to the EMTEC TSA Softness and Flexibility Test Methods described herein.
A fourth group of example nonwoven webs (FZD-10, FZD-40) were formed using the apparatus 800 described with respect to
The examples FZD-10, FZD-40, and Control 2 were formed having a total basis weight of 70 gsm. The secondary fibrous material used was pulp mats supplied by Georgia-Pacific (rolled, ECF-bleached, southern pine, softwood kraft fluff pulp treated with debonder and antistatic agent(s), medically and FDA-approved, and BfR compliant) and comprised approximately 70% by weight of each example nonwoven web (i.e., 49 gsm). The meltblown fibrous material used was a high melt flow rate metallocene-based polypropylene homopolymer (Metocene MF650X manufactured by LyondellBassell) and comprised approximately 30% by weight of each example nonwoven web (i.e., 21 gsm). The softening agent used was silicone (WACKER HC 3502) and was provided in different amounts in each example nonwoven web (from about 0.000-0.302 gsm, or 0 to 40 lbs/MT pulp). The softening agent manifold used included four spray nozzles, each a McMaster-Carr No-Drip Flat Spray Nozzle (part number 4846T112) having a diameter of 0.02 inches and each spaced 4.0 inches apart from each other in a linear row. Particular characteristics of the example webs FZD-10, FZD-40, and Control 2 are shown below in TABLE 7.
TABLE 8 reports on performance properties of the example nonwoven webs FZD-10, FZD-40, and Control 2. More specifically, the example nonwoven webs FZD-10, FZD-40, and Control 2 were tested for strength according to the CDT and MDT Strength Test Methods described herein and for softness and flexibility according to the EMTEC TSA Softness and Flexibility Test Methods described herein.
A fifth group of example webs (EXP-40, EXP-60, EXP-80) were formed using an apparatus similar to the apparatus 600 described with respect to
The examples EXP-40, EXP-60, EXP-80, and Control 3 were formed having a total basis weight of 70 gsm. The secondary fibrous material used was pulp mats supplied by International Paper (rolled, ECF-bleached, southern pine, softwood kraft fluff pulp treated with debonder and antistatic agent(s), medically and FDA-approved, and BfR compliant) and comprised approximately 73% by weight of each example nonwoven web (i.e., 51 gsm). The meltblown fibrous material used was a high melt flow rate metallocene-based polypropylene homopolymer (Achieve™ Advanced PP6945G1 manufactured by ExxonMobil) and comprised approximately 27% by weight of each example nonwoven web (i.e., 19 gsm). The softening agent used was silicone (WACKER HC 3502) and was used to pretreat the pulp mats in different amounts (from about 0.000-0.630 gsm, or 0 to 80 lbs/MT pulp). Particular characteristics of the example webs EXP-40, EXP-60, EXP-80, and Control 3 are shown below in TABLE 9.
TABLE 10 reports on performance properties of the example nonwoven webs EXP-40, EXP-60, EXP-80, and Control 3. More specifically, the example nonwoven webs EXP-40, EXP-60, EXP-80, and Control 3 were tested for strength according to the MDT Strength Test Method described herein and for softness and flexibility according to the EMTEC TSA Softness and Flexibility Test Methods described herein.
As seen in TABLES 1-10, the example nonwoven webs produced according to the methods and apparatuses described herein in which silicone is used (i.e., PSD-10, PSD-40, PSU-2.5, PSU-5, PSU-10, PSU-20, PSU-40, PSU-80MSD-10, MSD-20, MSD-40, FZD-10, FZD-40, EXP-40, EXP-60, EXP-80) generally have improved softness values (TS7) compared to the control webs in which silicone was not used (i.e., Control 1, Control 2, Control 3). Furthermore, the example nonwoven webs in TABLES 1-10 demonstrate that, as more silicone is added to the nonwoven mixture, the softness (TS7) of the nonwoven webs generally improves. TABLES 1-10 also show that the example nonwoven webs exhibit improved flexibility (mm/N) and maintained sufficient strength (gf).
Additionally, the example nonwoven webs surprisingly showed a sufficient combination of softness, flexibility, and strength while using relatively low amounts of silicone. In many examples, softness values of less than 6.0 (TS7) were achieved using 0.079 gsm (10 lb/MT pulp) of silicone while maintaining sufficient strength and flexibility. In further examples, softness values of less than 5.0 (TS7) were achieved using 0.302 gsm (40 lb/MT pulp) (or less) of silicone while maintaining sufficient strength and flexibility.
For methods in which a softening agent stream is merged with a secondary fibrous material stream (to form a combined stream of softening agent and secondary fibrous material), Applicant has surprisingly found that merging the softening agent with the secondary fibrous material stream on a side of the secondary fibrous material stream that is downstream relative to the machine direction of the forming surface (e.g., as depicted with respect to the apparatus 200 in
In various implementations, the nonwoven web structures disclosed herein (e.g., the nonwoven web 100 of
The amount of liquid contained within each wet wipe may vary depending upon the type of material being used to provide the wet wipe, the type of liquid being used, the type of container being used to store the wet wipes, and the desired end use of the wet wipe. Generally, each wet wipe can contain from about 150 to about 600 weight percent and desirably from about 250 to about 450 weight percent liquid based on the dry weight of the wipe for improved wiping. In a particular aspect, the amount of liquid contained within the wet wipe is from about 250 to about 300 weight percent based on the dry weight of the wet wipe. If the amount of liquid is less than the above-identified ranges, the wet wipe may be too dry and may not adequately perform. If the amount of liquid is greater than the above-identified ranges, the wet wipe may be over saturated and soggy and the liquid may pool in the bottom of the container.
Each wet wipe may be generally rectangular in shape and may have any suitable unfolded width and length. For example, the wet wipe may have an unfolded length of from about 2.0 to about 80.0 centimeters and desirably from about 10.0 to about 25.0 centimeters and an unfolded width of from about 2.0 to about 80.0 centimeters and desirably from about 10.0 to about 25.0 centimeters. Typically, each individual wet wipe is arranged in a folded configuration and stacked one on top of the other or a continuous strip of material which has perforations to provide a stack of wet wipes. The stack of wet wipes may be placed in the interior of a container, such as a plastic tub, and arranged in a stack for dispensing to provide a package of wet wipes for eventual sale to the consumer.
As disclosed herein, applying functional chemistries (e.g., softening agents) during the nonwoven web (basesheet) forming process results in several advantages, including improved basesheet softness, improved basesheet retention, and other improved basesheet properties. Using the methods described herein, Applicant has surprisingly found that, by applying a softening agent during the formation of the nonwoven web (basesheet), suitable softness (TS7) can be achieved without including a softening agent in the liquid formulation added to the basesheet to form a wet wipe. In other words, the nonwoven web itself (the basesheet) has softness properties that enable the liquid formulation applied to the basesheet to be free of softening agents in various implementations.
Furthermore, Applicant has surprisingly found that the methods described herein enable suitable softness values to be achieved using substantially less softening agent (in comparison to wet wipes in which no softening agent is used during formation of the basesheet and instead included in the liquid formulation). For example, Applicant has surprisingly found that application of a softening agent during the basesheet forming process (as shown and described herein with respect to the apparatuses 200-800) can produce nonwoven webs having suitable softness properties (and sufficient strength and flexibility) using approximately 55% less softening agent (e.g., a nonwoven web made according to the methods herein using about 0.302 to 0.315 gsm of silicone would have softness properties substantially the same as a conventional wet wipe having approximately 0.567 gsm of silicone applied via the liquid formulation, for comparable web basis weights). Accordingly, as described herein, various implementations provide for more efficient manufacturing of nonwoven web materials, as well as wet wipe products made from the same.
In certain implementations, when a softening agent is added to the basesheet during the forming process and the basesheet is then used to form a wet wipe product, a wider array of liquid formulations can be added to the basesheet. For example, in certain implementations, the improved softness of the basesheet may enable the liquid formulation to be free of softening agents, which facilitates the use of a wider array of functional chemistries while maintaining stability of the liquid formulation (e.g., chemistries that would otherwise compromise the stability of the liquid formulation if included with a softening agent). Various implementations of the devices, systems, and methods disclosed herein thus provide for a more flexible option for producing wet wipes and other nonwoven web materials with various liquid formulation chemistries, which results in improved consumer-desirable properties in the wet wipe product (e.g., softness, gentleness, and strength).
The nonwoven web of the present disclosure may alternatively be used in a wide variety of articles. For example, the web may be incorporated into an “absorbent article” that is capable of absorbing water or other fluids. Examples of some absorbent articles include, but are not limited to, personal care absorbent articles, such as diapers, training pants, absorbent underpants, incontinence articles, feminine hygiene products (e.g., sanitary napkins), swim wear, and so forth; medical absorbent articles, such as garments, fenestration materials, underpads, bedpads, bandages, absorbent drapes, and medical wipes; clothing articles; pouches; and so forth. Materials and processes suitable for forming such articles are well known to those skilled in the art. Several examples of such absorbent articles are described in U.S. Pat. No. 5,649,916 to DiPalma, et al.; U.S. Pat. No. 6,110,158 to Kielpikowski; U.S. Pat. No. 6,663,611 to Blaney, et al., which are incorporated herein in their entirety by reference thereto for all purposes. Still other suitable articles are described in U.S. Patent Application Publication No. 2004/0060112 A1 to Fell et al., as well as U.S. Pat. No. 4,886,512 to Damico et al.; U.S. Pat. No. 5,558,659 to Sherrod et al.; U.S. Pat. No. 6,888,044 to Fell et al.; and U.S. Pat. No. 6,511,465 to Freiburger et al., all of which are incorporated herein in their entirety by reference thereto for all purposes. When employed in the absorbent article, the nonwoven web of the present disclosure may form a component of the absorbent core or any other absorbent component of the absorbent article as is well known in the art.
While various implementations have been described in detail herein, it will be appreciated that those skilled in the art, upon attaining an understanding of the foregoing, may readily conceive of alterations to, variations of, and equivalents to these implementations. In addition, it should be noted that any given range presented herein is intended to include any and all lesser included ranges. For example, a range of from 45-90 would also include 50-90; 45-80; 46-89, and the like.
EMTEC TSA Softness and Flexibility Test MethodsThe softness and flexibility (stiffness) of the nonwoven webs were measured using an EMTEC Tissue Softness Analyzer (“TSA”) (Emtec Electronic GmbH, Leipzig, Germany). Softness was measured in terms of the TS7 value, while flexibility was measured in terms of mm/N.
The TSA comprises a rotor with vertical blades which rotate on the test piece applying a defined contact pressure. Contact between the vertical blades and the test piece creates vibrations, which are sensed by a vibration sensor. The sensor then transmits a signal to a PC for processing and display. The signal is displayed as a frequency spectrum. For measurement of TS7 values, the blades are pressed against sample with a load of 100 mN and the rotational speed of the blades is 2 revolutions per second.
To measure TS7 values, a frequency analysis is performed in the range of approximately 1 kHz to 10 kHz, with the amplitude of the peak occurring at 7 kHz being recorded as the TS7 value. The TS7 value represents the softness of the sample and a lower amplitude correlates to a softer sample. The TS7 values have the units dB V2 rms.
Test samples were prepared by cutting a circular sample having a diameter of 112.8 mm. All samples were allowed to equilibrate at TAPPI standard temperature and humidity conditions for at least 24 hours prior to completing the TSA testing. For measurement of the non-wire side (NWS) softness, the sample is placed in the TSA with the air side of the sample facing upward (the side of the sample collected on the forming wire facing downward). For measurement of the wire-side (WS) softness, the sample is placed in the TSA with the air side of the sample facing downward (the side of the sample collected on the forming wire facing upward). The sample is secured, and the measurements are started via the PC. The PC records, processes and stores all of the data according to standard TSA protocol. The reported values are the average of 5 replicates, each one with a new sample.
SamplesAs used herein, the term flexibility (or stiffness parameter (D)) refers to the output of the TSA in mm/N. Generally, the flexibility value (reported in mm/N) is a measure of the deformation of a sample under a defined load. The data for flexibility is collected while the rotor with the blades is pressed in two cycles with two different forces on the test piece. Force 1 (100 mN) and then force 2 (600 nM) are applied to the test piece as a pre-elongation to measure the displacement D.
The TSA softness and flexibility test methods, the TSA is calibrated according to EMTEC's instructions using the 1-point calibration method with the appropriate reference standards (e.g., “ref.2 samples” or equivalent, which are available from EMTEC).
CDT and MDT Strength Test MethodsThe CDT Strength Test Method measures the peak load value—the maximum force produced by a specimen when it is pulled to break in the cross-machine direction (CD). The samples are cut to a width of 25 mm and a length of 152 mm using a die cutter or using a sample cutter such as a JDC Precision Sample Cutter (Thwing-Albert Instrument Company, Philadelphia, Pa., Model No. JDC 3-10, Ser. No. 37333) and conditioned at 23±2° C. and 50±5% relative humidity for at least 4 hours before testing and are tested at the same ambient conditions. The length dimension of the sample should extend in a cross-machine direction (CD) of the web from which the sample is cut. The CDT Strength value is the peak load in grams-force when a sample is pulled to rupture (the cross-machine direction tensile strength). More specifically, the CDT Strength value is the peak load when the sample is pulled with a force oriented in a direction crosswise to the machine-direction orientation of the sample.
The MDT Strength Test Method measures the peak load value—the maximum force produced by a specimen when it is pulled to break in the machine direction (MD). The samples are cut to a width of 25 mm and a length of 152 mm using a die cutter or using a sample cutter such as a JDC Precision Sample Cutter (Thwing-Albert Instrument Company, Philadelphia, Pa., Model No. JDC 3-10, Ser. No. 37333) and conditioned at 23±2° C. and 50±5% relative humidity for at least 4 hours before testing and are tested at the same ambient conditions. The length dimension of the sample should extend in a machine direction (MD) of the web from which the sample is cut. The MDT Strength value is the peak load in grams-force when a sample is pulled to rupture (the machine direction tensile strength). More specifically, the MDT Strength value is the peak load when the sample is pulled with a force oriented in the machine-direction orientation of the sample.
The tensile strength test instrument for the CDT and MDT Strength Test Methods is an MTS Criterion 41 or 43 and MTS TestSuite Elite™ (MTS Systems Corp., Research Triangle Park, NC). The load cell is selected such that the peak load values fall between 10 and 90 percent of the load cell's full-scale load—either a 50 Newton or 100 Newton maximum load cell may typically be appropriate depending on the strength of the sample being tested. The gauge length is 76 mm, and the jaw width is 76 mm with an approximate height of 12.7 mm. The crosshead speed is 305 mm/minute, and the break sensitivity is set at 70%.
The sample is placed in the jaws of the instrument and centered both vertically and horizontally with the longer dimension parallel to the direction of the load application. The jaws are operated using pneumatic-action and are rubber coated. The test is then started and ends when the specimen breaks. The peak load is determined and reported as the CDT (or MDT) Strength value of the sample, to the nearest 0.1 gf. Five (5) representative specimens are tested, and the arithmetic average of all individual specimen tested is the tensile strength for the product.
Example ImplementationsA number of example implementations are provided herein. However, it is understood that various modifications can be made without departing from the spirit and scope of the disclosure herein. As used in the specification, and in the appended claims, the singular forms “a,” “an,” “the” include plural referents unless the context clearly dictates otherwise. The term “comprising” and variations thereof as used herein is used synonymously with the term “including” and variations thereof and are open, non-limiting terms. Although the terms “comprising” and “including” have been used herein to describe various implementations, the terms “consisting essentially of” and “consisting of” can be used in place of “comprising” and “including” to provide for more specific implementations and are also disclosed.
Disclosed are materials, systems, devices, methods, compositions, and components that can be used for, can be used in conjunction with, can be used in preparation for, or are products of the disclosed methods, systems, and devices. These and other components are disclosed herein, and it is understood that when combinations, subsets, interactions, groups, etc. of these components are disclosed that while specific reference of each various individual and collective combinations and permutations of these components may not be explicitly disclosed, each is specifically contemplated and described herein. For example, if a device is disclosed and discussed each and every combination and permutation of the device are disclosed herein, and the modifications that are possible are specifically contemplated unless specifically indicated to the contrary. Likewise, any subset or combination of these is also specifically contemplated and disclosed. This concept applies to all aspects of this disclosure including, but not limited to, steps in methods using the disclosed systems or devices. Thus, if there are a variety of additional steps that can be performed, it is understood that each of these additional steps can be performed with any specific method steps or combination of method steps of the disclosed methods, and that each such combination or subset of combinations is specifically contemplated and should be considered disclosed.
Claims
1. A fibrous nonwoven structure comprising:
- at least one meltblown fibrous material having an average diameter of about 0.5 to 50 μm; and
- at least one secondary fibrous material, wherein a weight ratio of the meltblown fibrous material to the secondary fibrous material is between 10/90 to 60/40;
- wherein the fibrous nonwoven structure has a TS7 value less than 7.0.
2. The fibrous nonwoven structure of claim 1, further comprising a softening agent.
3. The fibrous nonwoven structure of claim 1, wherein the softening agent comprises silicone.
4. The fibrous nonwoven structure of claim 1, wherein the fibrous nonwoven structure has a TS7 value of less than about 6.0.
5. The fibrous nonwoven structure of claim 4, wherein the fibrous nonwoven structure has a TS7 value of less than about 5.0.
6. The fibrous nonwoven structure of claim 1, wherein a weight ratio of the softening agent to the secondary fibrous material is in a range of 10 lb/MT to 80 lb/MT.
7. The fibrous nonwoven structure of claim 6, wherein a weight ratio of the softening agent to the secondary fibrous material is in a range of 20 lb/MT to 60 lb/MT.
8. The fibrous nonwoven structure of claim 7, wherein a weight ratio of the softening agent to the secondary fibrous material is 40 lb/MT.
9. The fibrous nonwoven structure of claim 1, wherein the meltblown fibrous material comprises a polymer.
10. The fibrous nonwoven structure of claim 9, wherein the polymer comprises polypropylene.
11. The fibrous nonwoven structure of claim 9, wherein the polymer comprises polyethylene.
12. The fibrous nonwoven structure of claim 1, wherein the secondary fibrous material comprises wood pulp.
13. The fibrous nonwoven structure of claim 1, wherein the weight ratio of the meltblown fibrous material to the secondary fibrous material is in the range of 20/80 to 60/40.
14. The fibrous nonwoven structure of claim 13, wherein the weight ratio of the meltblown fibrous material to the secondary fibrous material is in the range of 25/75 to 40/60.
15. The fibrous nonwoven structure of claim 14, wherein the weight ratio of the meltblown fibrous material to the secondary fibrous material is 30/70.
16. The fibrous nonwoven structure of claim 1, wherein the fibrous nonwoven structure has a flexibility between about 2.5 mm/N and 3.5 mm/N.
17. The fibrous nonwoven structure of claim 16, wherein the fibrous nonwoven structure has a flexibility between about 2.7 mm/N and 3.1 mm/N.
18. The fibrous nonwoven structure of claim 1, wherein the fibrous nonwoven structure has cross-machine direction tensile strength between about 200 gf and 400 gf.
19. The fibrous nonwoven structure of claim 18, wherein the fibrous nonwoven structure has cross-machine direction tensile strength between about 250 gf and 350 gf.
20. The fibrous nonwoven structure of claim 1, wherein the fibrous nonwoven structure has machine-direction tensile strength between about 400 gf and 860 gf.
21. The fibrous nonwoven structure of claim 20, wherein the fibrous nonwoven structure has machine-direction tensile strength between about 400 gf and 550 gf.
Type: Application
Filed: Dec 30, 2022
Publication Date: Jul 16, 2026
Inventors: David J. TREBATOSKI (Atlanta, GA), Kenneth B. CLOSE (New London, WI)
Application Number: 19/135,292
