Patent Application
20240200274
Molded pulp article comprising two or more regions in a single layer, wherein the two or more regions differ based on fiber type.
Forming articles from cellulosic materials such as paper and pulp has become a point of increasing interest as part of a general movement towards renewal feedstocks. Currently, cellulosic articles are generally formed from either a dry process where sheets of pulp (i.e. paper) and/or loose pulp are combined and compressed into the shape of the desired article, or a wet process where cellulosic fibers (i.e. pulp) is suspended (usually in water) as a slurry which is then formed onto a porous mold and subsequently dried to provide the article of the desired shape. The slurry may further include additives to modify the properties of the cellulosic material.
Current wet-formed molded pulp articles are generally formed from a single pulp slurry. In some instances, a pulp article may be formed that has different properties in different regions of the article, but these properties are attained by manipulation of forming steps in addition to the original molding step. For example, additional layers of pulp may be applied in certain areas following the original formation step to increase the thickness of certain regions. The addition of multiple pulp layers increases the cost of production due to increased complexity and time for manufacturing.
Separately, during the pulp molding step differing levels of thickness of the pulp on the forming mold can be achieved by varying the degree of pressure/vacuum that is applied when forming the slurry onto the porous mold (US20190240926). These techniques are limited to only modifying the properties of the pulp article based on the wall thickness of the molded article.
A further method to alter the characteristics of a molded pulp article involves the use of coatings including the use of multiple coatings. Coatings are different from slurry additives in that coatings are generally applied after the cellulosic article is formed. Coatings can be applied using any manner of conventional techniques, from dipping to spraying; but the use of coatings faces the same disadvantages as using multiple layers, in that it results in additional post molding processing steps, increased time and cost.
The desire to form articles from cellulosic materials further includes the desire to form articles that vary in their properties across regions of the article. For example, a bottle formed from plastic can be formed to have rigidity relative to top-loading while further including a flexible panel that a user can squeeze in order to dispense product from the bottle.
What is needed in the art is a pulp molded article having a pulp layer with varying regional properties without the need for any post molding steps.
A multi-region pulp article is provided that comprises a first region comprising a first pulp-fiber type; a second region comprising a second pulp-fiber type; wherein the first region and the second region are disposed in a single pulp layer; wherein the first fiber-type differs from the first second fiber-type, wherein at least one of the first region or second region comprises one or more additives.
While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter that is regarded as the present disclosure, it is believed that the disclosure will be more fully understood from the following description taken in conjunction with the accompanying drawings. Some of the figures may have been simplified by the omission of selected elements for the purpose of more clearly showing other elements. Such omissions of elements in some figures are not necessarily indicative of the presence or absence of particular elements in any of the exemplary embodiments, except as may be explicitly delineated in the corresponding written description. None of the drawings are necessarily to scale.
The present invention includes a pulp molded article (article) with two or more regions containing different fiber types. The different fiber types may include different cellulosic materials formed together to create pulp-based composites (molded composites).
The different fiber types comprising the different regions on the article provide different properties to the regions. These different properties can be attained without the need to vary the thickness of the material used in forming the different regions. Exemplary properties conferred to the different regions include compressive strength, tensile strength, folding endurance, surface roughness, porosity, surface tension, water vapor transmission rate, density, rigidity, brightness.
“Substantially parallel,” with respect to two coplanar lines of direction, describes lines of direction that are precisely parallel (never intersect), and coplanar lines of direction that intersect and thereby deviate from precisely parallel, by no more than 10 degrees.
“Substantially perpendicular,” with respect to two coplanar lines of direction, describes lines of direction that are precisely perpendicular (intersect at an angle of 90 degrees), and coplanar lines of direction that deviate from precisely perpendicular by no more than 10 degrees (i.e., intersect at an angle from 80 degrees to 100 degrees).
As used herein, “substantially cylindrical” refers to and includes the outer shape of a cylinder, but also includes shapes such as slightly oblate or slightly flattened cylinders, slightly curved cylinders, and other tubular shapes which have diameters and/or cross-sectional areas that vary slightly along their lengths, wherein minor deviation from a precise cylindrical shape does not compromise product manufacturability, function or utility.
The “longitudinal axis” is a centerline extending along the length of an article.
“Lateral” refers to a direction perpendicular to its longitudinal axis. “Width” refers to a dimension measured along a direction perpendicular to the longitudinal axis.
“Cross section” refers to a perimeter or area outlined by a feature of an article measured along a direction perpendicular to the longitudinal axis.
“Longitudinal” refers to a direction parallel to its longitudinal axis. “Length” refers to a dimension measured along a direction parallel to the longitudinal axis.
“Axial” movement of an element means movement along the longitudinal axis of an element. An “axial” direction is substantially parallel to the longitudinal direction.
“Coaxial” refers to the movement of an ejection plunger within a barrel portion of an applicator assembly, whereby the plunger moves within the barrel portion and substantially along and/or parallel to longitudinal axis of the barrel portion.
“Cellulosic material”
The cellulosic material used in forming a given region of the article may include a random (i.e. not layered) mixture of fiber types.
The terms “cellulose.” “cellulosic material”, “cellulose fibers,” “cellulose pulp” and “cellulose pulp fibers,” as used herein, include cellulosic fibers obtained or derived from plants, such as wood fiber, wood pulp, and other natural plant fibers, regenerated cellulose fiber such rayon, viscose or cuprammonium rayon, and high pulping yield fibers, unless specified differently. These terms also include chemically treated natural plant fibers, such as mercerized pulps, chemically stiffened or crosslinked fibers, or sulfonated fibers. Also included are mercerized natural plant fibers, regenerated natural cellulosic fibers, fibers of cellulose produced by microbes, the rayon process, cellulose dissolution and coagulation spinning processes, and other cellulosic material or cellulosic derivatives. Other cellulose fibers included are paper broke or recycled fibers and high yield fibers. High yield pulp fibers are those fibers produced by pulping processes providing a yield of about 65% or greater, more specifically about 75% or greater, and still more specifically about 75% to about 95%. Yield is the resulting amount of processed fibers expressed as a percentage of the initial wood mass. Such pulping processes include bleached chemithermomechanical pulp (BCTMP), chemithermomechanical pulp (CTMP), pressure/pressure thermomechanical pulp (PTMP), thermomechanical pulp (TMP), thermomechanical chemical pulp (TMCP), high yield sulfite pulps, and high yield Kraft pulps, all of which leave the resulting fibers with high levels of lignin but are still considered to be natural fibers.
The term “natural plant fibers” as used herein, refers to cellulosic fibers obtained from plants, including wood fibers and wood pulp fibers such as those obtained from deciduous and coniferous trees, including softwood fibers, such as northern and southern softwood kraft fibers; and hardwood fibers, such as eucalyptus, maple, birch, beech, oak, sweetgum, and aspen; and non-wood cellulosic fibers, such as those of bamboo, cotton, abaca, kenaf, sabai grass, flax, esparto grass, straw, jute hemp, bagasse, milkweed floss, and pineapple leaf.
Cellulose pulp fibers can be prepared in high-yield or low-yield forms and can be pulped in any known method, including kraft, sulfite, high-yield pulping methods and other known pulping methods. Natural plant fibers contemplated by the present disclosure may include recycled fibers, virgin fibers or mixes thereof.
“Fiber type” as used herein refers to the fibrous material or materials that comprise the cellulosic materials that form the article. Different fiber types may be distinguished from one another on the basis of their source (i.e. wood fibers such as hardwood or softwood, non-wood fibers such as cotton, manufactured fibers such as rayon or Lyocell, or reclaimed/recycled fibers), on the basis of the means by which the source was processed to yield the fibers (i.e. chemical processing, mechanical processing, chemi-mechanical processing), or on the basis of a physical property of the fibers themselves (i.e. fiber length, fiber width, fiber coarseness, degree of fibrillation (i.e. micro-fibrillated cellulose), fiber Canadian freeness, amount of fines). Fiber types may be distinguished from one another as differing in one of more of these aspects.
Non-limiting examples of hardwood fibers include fibers derived from hardwood sources such as eucalyptus, maple, birch, beech, oak, sweetgum, and aspen. Non-limiting examples of softwood fibers include fibers derived from softwood sources such as pine, spruce, and fir. Non-limiting examples of non-wood fibers include fibers derived from non-wood sources such as bamboo, cotton, abaca, kenaf, sabai grass, flax, esparto grass, straw, jute hemp, bagasse, milkweed floss, corn stover, miscanthus, pineapple leaf, and linen. Non-limiting examples of manufactured fibers include fibers derived from regenerated cellulose, such as viscose rayon, Lyocell, regenerated bamboo. Non-limiting examples of reclaimed/recycled fibers include fibers derived from post-industrial recycled (PIR) waster or post-consumer recycled waste (PCR) and may include Mixed paper, old newspaper/newsprint (ONP), old corrugated containers (OCC), pulp substitutes (unprinted, uncoated, unadulterated paper and board), high-grade deinked,
Non-limiting examples of chemically processed fibers include Kraft, sulfite, and soda. Non-limiting examples of mechanically processed fibers include stone-ground wood, refiner-mechanical pulp (RMP), and thermomechanical pulp (TMP). Non-limiting examples of chemi-mechanically processed fibers include Chemiground wood, Cold soda, NSSC (Neutral sulfite semi-chemical), High yield sulfite, High yield kraft.
Non-limiting examples of fiber physical properties include fiber length, fiber width, fiber coarseness, drainability, cellulose solution viscosity (cellulose degree of polymerization).
“Additive” as used herein refers to a non-cellulosic material included with the cellulosic material (i.e. different fiber types) in the slurry. Additive are distinguished from coating in that coatings are applied to one or more surfaces of the article after it is formed, while additives are included in the slurry and therefore generally incorporated within and evenly dispersed throughout the cellulosic material forming a region of the article.
Additives may impart any of a number of properties to the cellulosic material and therefore to the region of the article. These properties may derive primarily from the incorporation of the additive itself or may further be modified by any post-formation treatment of the article such as drying or compressing.
Additives may be used for “sizing” or to impart resistance to fluid penetration to the cellulosic material. Non-limiting examples of sizing agents include non-reactive systems such as rosin systems commonly used in acidic papermaking, natural resin can be processed from southern pines tall oil (a byproduct from alkaline pulping), and reactive systems such as those based on alkyl ketene dimers or alkenylsuccinic anhydrides. Other non-limiting examples of sizing agents may include acid chlorides, acid anhydrides, enol esters, alkyl isocyanates, rosin anhydrides, starch (including amylose and/or amylopectin), animal glue, methyl cellulose, carboxymethyl cellulose (CMC), polyvinyl alcohol, waxes and wax emulsions, alginates, or polymers such as Styrene Maleic Anhydride (SMA), polyurethanes, and styrene acrylate.
Additives may be used to provide strength to the cellulosic material including wet strength and/or dry strength. Non-limiting examples of wet strength additives include thermosetting resins such as amino resins including urea-formaldehyde resins, thermosetting aminoplastic resins such as melamine formaldehyde resins, amine-epichlorohydrin resins such as amine-epichlorohydrin polymeric resins, polyamide-epichlorohydrin resins, polyamide-amine-epichlorohydrin (PAE) resins and the like, glyoxalated polyacrylamide (GPAM) resins including crosslinked and non-crosslinked GPAM polymers, modified starch such as dialdehyde starch, and/or polycarboxylic acids. Non-limiting examples of dry strength additives include polysaccharides and modified polysaccharides such as starch (including amylose and/or amylopectin), modified starch, modified cellulose(s) such as carboxymethyl cellulose (CMC) and/or chitosan, as well as crosslinked/branched polysaccharides such as hemicellulose(s) and/or polysaccharide gums including locust gum and/or tamarind gum and/or guar gum among others, cationic and/or anionic modified polysaccharides including combinations of cationic and anionic modified polysaccharides as polyelectrolyte multilayers (PEM's), polyacrylamides (PAMs), and latex additives.
Additives may also include colorants (i.e. dyes and pigments). It has been found that fiber-based articles may be relatively unaffected in quality, by addition of limited quantities of pigments, colorants and filler materials, provided that the pigment material selected is not chemically reactive with water or any of the other components of the molding composite under the molding conditions referenced herein. Accordingly, the composite described herein enables the manufacturer to mold parts in a large variety of colors. In order to avoid substantial effect on the moldability of the composite, it is believed that pigment, if desired, should be included to a maximum of 5 percent, more preferably 4 percent, and still more preferably 3 percent, by weight of the dry component blend.
Additives may also include fillers which impart various properties to the article or article region including brightness, opacity, whiteness, gloss, smoothness, and printability. Fillers can also be used to modify the density of the article or region. Non-limiting examples of fillers include titanium dioxide, clays such as kaolin, calcium carbonate, aluminum trihydrate, silicas, silicates and aluminosilicates, and calcium sulfoaluminates.
Additives may include binders that impart structural integrity to the article. Any suitable binder may be used, but binders that exhibit human bio-compatibility, relatively rapid biodegradability, source sustainability and dispersibility are preferred. Polysaccharides including starches (e.g. corn starch and/or potato starch) may be suitable binders.
Additives may include dispersing agents that may facilitated the dispersion of a co-additive in the slurry. Dispersing agents may be particularly useful for dispersing co-additives which are not fully water-soluble such as hydrophobic or hydrophobically-modified additives, or particulate additives. Non-limiting examples of dispersing agents include salts of carboxymethylcellulose such as sodium carboxymethylcellulose (CMC salt).
Additives may include lubricating agents that may improve releasability of the molded article from the mold (i.e., reducing chances that the molded object will stick to the mold). Non-limiting examples of lubricating agent may include long-chain fatty acids and salts thereof such as non-alkali metal salts thereof such as calcium stearate, magnesium stearate, zinc stearate, calcium laurate, magnesium laurate, zinc laurate, aluminum laurate, strontium laurate, aluminum stearate, strontium stearate, and mixtures thereof.
If a lubricating agent is desired the lubricating agent may preferably be included in a quantity from 0.2 to 2.0 weight percent of the total dry component blend.
Additives may be at least partially water-soluble and may be at least partially dissolved in the slurry or may be particulate. The additive(s) may be suspended in the slurry as particles or as emulsions or dispersions.
“Slurry” as used herein refers to the suspension of the cellulosic material(s), fiber type(s) and additive(s) that is applied to the porous mold when forming the article. The slurry is generally, but not necessarily, suspended in water. The slurry may be dilute and contain a high (i.e. >90% w/w) amount of water or may be concentrated and contain a low (i.e. <90% w/w) amount of water.
Water is added to the dry wood pulp fibers and any additives to transform the dry components into a moldable paste or slurry. The quantity of water added may be varied to achieve an optimized balance of viscosity and minimization of the quantity of water that must be removed during the drying process following formation.
The volume ratio of dry component blend to water may be from 55:45 to 75:25, and may be adjusted according to the desired dry component composition selected for optimized viscosity and water content for molding and molded object porosity. In other examples, dry/precursor components of the molding composite may be dispersed in a relatively high-water content slurry, as disclosed in, by way of non-limiting example, PCT App. No. WO 2020/016416, which is incorporated herein by reference in its entirety.
“Region” as used herein refers to area of an article that contains a fiber type. Different regions of an article are comprised of different fiber types. The different regions of the article can be conferred with different properties on the basis of the fiber type(s) comprising the cellulosic material forming each region. Such properties may include density, rigidity/flexibility, porosity, water vapor transmission rate (WVTR), absorbency, surface tension, surface smoothness, tensile strength, compressive strength, folding endurance. A region's size, shape, and thickness will depend upon a number of factors, such as the type of articles and its intended use, components of the region, desired properties of the region, desired properties of other regions, method of manufacture. The composition of a region can include fiber type(s) and additive(s).
An article may be formed to comprise regions of different density or basis weight. Densities of the various regions may have any practical value that suits the purpose of the article and the regions of the article. For example, a region of the article may have densities from about 0.2 to 2.0 g/cm3. Varying the density (or basis weight) of the different regions of the article may further contribute to differences in other mechanical properties such as tensile strength, compressive strength, drop strength, and strength at the opening. Density of basis weight can be measured by any known means in the art such as by determining the weight of a region and separately determining its thickness (e.g. by using calipers) and calculating density as weight divided by thickness.
An article may be formed to comprise regions of different tensile strength. Tensile strength of the various regions may have any practical value that suits the purpose of the article and the regions of the article. For example, a region of an article may have a tensile strength of 5 MPa or more, particularly 10 MPa or more. Articles with tensile strengths in these ranges are less prone to rupture due to shocks, etc. Tensile strength can be measured by any known means in the art such as by compendial methods Tappi T494.
An article may be formed to comprise regions of different compressive strength. Compressive strength of the various regions may have any practical value that suits the purpose of the article and the regions of the article. For example, a region of an article may have a compressive strength of 100 Nm2/g or more, particularly 110 Nm2/g or more. Compressive strengths within these ranges allow articles to survive compression insults, such as those caused during travel or storage.
An article may be formed to comprise regions of different water vapor transmission rate (WVTR). WVTR of the various regions may have any practical value that suits the purpose of the article and the regions of the article. For example, a region may have a WVTR of 100 g/(m2·24 hrs) or less, preferably 50 g/(m2·24 hrs) or less. A low WVTR may be useful in minimizing the extent to which moisture in the air can penetrate the region, which may be important if the article is a container for moisture-sensitive contents. WVTR can be measured by any known means in the art such as by compendial methods Tappi T448 om-21 and T464 om-18.
An article may be formed to comprise regions of different surface tension. Surface tension of the various regions may have any practical value that suits the purpose of the article and the regions of the article. For example, a region may have a surface tension of 10 dyn/cm or less and water repellency of R10, which would imply the region has water repellency. Surface tension can be measured by any known means in the art such as by compendial methods Tappi T458.
“Transition Region” refers to an area of an article that is adjacent to a Region but contains less of a type of fiber present in the adjacent Region. The transition region may include fibers of both types of those in the regions to which it is adjacent. The transition region may be adjacent to more than two regions and as such may contain fibers of each of the types of those in the regions to which it is adjacent. In embodiments a transition region will typically blend or feather into the bordering regions, rather than forming an abrupt change. The multiple fiber types in the transition region may be randomly mixed or layered.
Transition regions can have a configuration corresponding to the border regions. The depth or size of a transition region will depend upon the one or more factors, such as the article and its intended use, composition of the regions, method of manufacture, and so on.
All temperatures herein are in degrees Celsius (° C.) unless otherwise indicated. Unless otherwise specified, all measurements herein are conducted at 20° C. and under the atmospheric pressure.
As used herein, the articles “a” and “an” when used in a claim, are understood to mean one or more of what is claimed or described.
As used herein, the terms “include,” “includes,” and “including” are meant to be non-limiting.
Unless otherwise noted, all component or composition levels are in reference to the active portion of that component or composition, and are exclusive of impurities, for example, residual solvents or by-products, which may be present in commercially available sources of such components or compositions.
All percentages and ratios are calculated by weight unless otherwise indicated. All percentages and ratios are calculated based on the total composition unless otherwise indicated.
Every maximum numerical limitation given throughout this specification includes every lower numerical limitation, as if such lower numerical limitations were expressly written herein. Every minimum numerical limitation given throughout this specification will include every higher numerical limitation, as if such higher numerical limitations were expressly written herein. Every numerical range given throughout this specification will include every narrower numerical range that falls within such broader numerical range, as if such narrower numerical ranges were all expressly written herein.
Various embodiments of the present invention are described below in
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A bottle of the present invention may be formed as a unitary part or may be formed from two or more parts that are joined after being formed. The two or more parts may be joined by any means known in the art such as adhesive binding, overlapping seams via folding, heat sealing, ultrasonic bonding and the like. The bottle may be formed from the joining of two portions, such as a front portion 61 and a back portion 63 as depicted in
Various embodiments of the present invention are described below in
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Articles of the present invention may be formed from a process that includes depositing the regionally disposed cellulosic materials on a porous forming male or female mold from an aqueous slurry. The mold may be in the form of a mirror image of the article to be manufactured and may take any form (i.e. porous plate, wire mesh, additively or subtractive created) capable of accepting the slurry and allowing deposition of the cellulosic material therefrom. Typically, the cellulosic material is deposited on the porous mold via pressure, including either (or both) of positive pressure applied to the slurry-facing side of the mold while the mold is exposed to the slurry or vacuum applied to the non-slurry facing side of the mold while the mold is exposed to the slurry. By establishing a pressure differential between the slurry-facing side of the mold and the non-slurry-facing side of the mold, the slurry is drawn to the surface of the pores on the porous mold, trapping fiber particles in the shape of the mold. The slurry may be applied to the porous mold by any means such as by immersion of the mold in the slurry, pouring of the slurry over the mold, spray-coating of the slurry onto the mold and the like.
The different fiber types comprising the different regions of the article may be deposited on the mold from different slurries The different slurries may be applied simultaneously or sequentially. Without being bound by theory it is believed that depositing the slurries simultaneously may result in the different fiber types comprising the different regions be randomly mixed within the transition region while sequential application of the slurries may result in layering of the different fiber types in the transition region.
Deposition of the fibers on the porous mold may continue until a desired thickness of the fibers on the mold is achieved, including the fibers comprising the various regions comprising the desired article. Following deposition of the fibers, the resulting accumulation of fibers in the rough form of the finished article (i.e. the article “blank”) is dried and/or cured. The process may be operated as a closed loop system, in that the unused slurry is re-circulated back into the system and re-used for forming a subsequent article.
Drying of the blank may be achieved by any means. For example the blank may simply be air-dried with no further processing. Alternately, the blank may be actively dried (i.e. with heat) and may further be subject to compression. Conventional “hot press” drying may include drying/curing the blank at a temperature range of about 150° C. to about 250° C., with a pressure range about 140 to about 170 kg/cm2.
The blank may be transferred to a transfer tool before or during the drying process. The transfer tool may also be porous to facilitate further drying of the blank. The blank may be subjected to further temperature and pressure while in contact with the transfer tool. The pressure applied to may be about 200 to about 900 mbarA (millibar absolute) or about 300 to about 800 mbarA. The temperature applied to the blank may be about 150-500° C., about 150-400°-C., 200-500°-C., 200-400°-C. or 200-300°-C., and in most cases 240-280° C. Typically, at least one mold face contacting the blank may be heated.
In an alternate embodiment the articles of the present invention may be made by injection molding as disclosed in US2022/0296434, which is incorporated herein by reference in its entirety.
After being formed, the articles of the present invention may have applied to them a topical coating of additives, such as preservatives, repellants, retardants, colorants, hardeners, anti-microbial substances, waxes, and/or resins for example. The shaped pulp articles of the present invention may, by way of non-limiting example only, be sprayed with a water repellant and/or stain repellant product in order to repel the infiltration of moisture and/or staining of the shaped pulp articles.
The different regions composed of the different fiber types may have different densities and/or different tensile strengths. The densities may vary from as low as about 350 kg/m3 to as high as about 1200 kg/m3 from one region to another. The tensile strengths may vary from as low as about 3 kN/m to as high as about 21 kN/m from one region to another.
Samples of multi-region pulp articles were prepared and tested as described below.
All measurements were performed in a laboratory maintained at 23° C.±2° C. and 50%±2% relative humidity and test samples were conditioned in this environment for 2 hours prior to testing.
The standard and experimental plaques reported in TABLE 1 were prepared according to the following procedure. The procedure generally follows the TAPPI T205 method for forming hand sheets with modifications as outlined herein. Standard plaques refer to non-regionalized plaques that may include a single fiber type or a homogeneous blend of fiber types. Experimental plaques refer to regionalized plaques in which different fiber types comprise different regions of the plaques.
The fibers were sourced from various pulp mills in the form of flat sheets or bundled fibers that have already gone through some form of pulping process. These supplied fiber forms first need to be re-separated and dispersed or suspended in water. This process of re-wetting and re-fiberizing is generally considered re-pulping. Any known repulping method and/or device could be used such as a blender (Waring Commercial Blender with modified blade) or a standard British disintegrator or lab pulper.
For the standard and experimental plaques reported in Table 1, a Waring Commercial Blender with modified blade was utilized. For the Samples listed in TABLE 1, plaques were made using the various fiber types, blends or regions. For each plaque the same amount of fiber (by weight) was used. This is generally referred to as the charge size or dose. The target dose for each experimental plaque tested was 10 g of total dry fiber for a circular plaque with diameter of ˜159 mm. To perform blended or zoned regions, the 10 g dose comprised the appropriate portion of each fiber type to be included in the final plaque. For example, a 50% portion would contain 5 g of that portion's type of fiber. From the supplied fibers, portions of convenient size were taken to achieve the target weight for the dose or dose portion. The target weight of fiber was measured using a balance accurate to 0.01 g. Each fiber portion was re-pulped as a separate charge or dose. Re-pulping was carried out at the consistency recommended by the re-pulping device manufacturer. Consistency is the ratio of fiber to water. Consistency (in percent) equals the fiber weight (in grams) divided by the sample volume used (in milliliters) times 100. Generally, the repulping devices were low consistency devices where the recommendation is less than 3% pulp in water. For the Samples listed in TABLE 1, 1000 ml of water was used for each sample in the repulping device. The amount of water was measured using a graduated cylinder or laboratory beaker. This water amount would result in a consistency of 0.5% for 5 g or 50% portion dose and 1% for 10 g 100% full dose. The same preparation and procedure would be used for any target dosage level or plaque dry weight.
With the fiber samples and water selected and measured, the re-pulping device was charged by combining the measured water and pulp. The resulting slurry was vigorously agitated in the blender for 1-4 minutes or until the fibers were separated and distributed in the water. This time could vary by fiber type, but for the Samples listed, the time was generally 2 minutes.
The plaques were then formed using a manual forming device. This laboratory device is available from various lab and instrument suppliers and meets the standards for Tappi 205 as represented in
Both standard plaques and experimental plaques were formed using the sheet former. Standard plaques refer to non-regionalized plaques that may include a single fiber type or a homogeneous blend of fiber types. Experimental plaques refer to regionalized plaques in which different fiber types comprise different regions of the plaques. To form plaques in the sheet former, after ensuring the drain valve was closed, the screen or mold was inserted and the column was closed and latched, the column was partially filled with water so that the column was at least halfway full. In a standard plaque forming process the full dosage or charge from the re-pulping device would be added to the column and dispersed into the previously added water to disperse and dilute the charge uniformly in the column. The drain valve can then be opened, and the water drains out of the column through the screen or mold and deposits the fibers on the screen or mold resulting in the formation of a wet sheet of fibers across the surface. When all of the water has drained out of the column, the column was opened for access and the wet sheet of fibers. The wet sheet can then be processed by any means.
The mold used in forming the Samples of TABLE 1 was a circular porous plate mold correlating to the 159 mm diameter of the sheet former.
A vacuum may be applied to the drain to more forcefully and rapidly draw the water through the altered screen or mold. The Samples in TABLE 1 were formed using a 110 cfm vacuum applied to the drain.
After being formed the wet sheets were subject to varying post-formation processing as indicated in TABLE 1. Sample 6 was processed by a largely conventional papermaking process in that the wet sheets were pressed using a roller and transferred to a dryer. Samples 1-5 and 7-9 were processed under temperature and pressure. After being removed from the mold, the plaques were transferred to a heated pressing device where the wet sheet was pressed with a controlled amount of pressure using a flat pressing surface. For the Samples in TABLE 1, pressure was set to 1500 psi. In addition, a fixed gap was set using gage blocks to prevent over pressure or damage to the screen or mold. This fixed gap was adjusted from 0 to 1 mm or larger. The primary gap for the Samples listed was 0.5 mm defined as the controlled gap between the surface of the screen or mold and the pressing surface. The pressure surface was set to a controlled temperature. Temperature was set to between 300-400 degrees Fahrenheit. Temperature could vary by fiber type due to the de-watering capability of the fibers (known in the art as freeness). The elevated temperature accelerates the removal of water as steam and the freeness of fibers can limit the rate at which the moisture can exit without damaging the sheet.
For standard plaques comprising 100% charge or dose of the same fiber type, the resulting hand sheet forming method was: To form sheets in the sheet former, after ensuring the drain valve was closed, the screen or mold was inserted and the column was closed and latched, and the column was partially filled with water so that the column was at least halfway full. The dosage or charge from the re-pulping device was added to the column and stirred into the previously added water to disperse and dilute the charge uniformly in the column. The vacuum source was then turned on and the drain valve can then be opened, and the water was drawn out of the column through the screen or mold and deposits the fibers on the screen or mold resulting in the formation of a wet sheet of fibers across the surface. When all of the water was drawn out of the column, the column was opened for access. The screen or mold with the wet sheet of fibers was then removed from the column and transferred to the heated pressing device. The wet sheet of fibers was then pressed with controlled pressure and temperature until sufficiently dry. The dried sheet was then removed from the mold for testing.
For standard plaques comprising homogeneous blends of different fibers where there was a partial charge or dose of each different fiber type, the resulting hand sheet forming method was: To form sheets in the sheet former, after ensuring the drain valve was closed, the screen or mold was inserted and the column was closed and latched, and the column was partially filled with water so that the column was at least halfway full. The various separate dosages or charges of each fiber type from the re-pulping device(s) were added to the column and stirred together into the previously added water to disperse and dilute the combined portions into a full charge uniformly in the column. The vacuum source was then turned on and the drain valve can then be opened, and the water was drawn out of the column through the screen or mold and deposits the fibers on the screen or mold resulting in the formation of a wet sheet of fibers across the surface. When all of the water was drawn out of the column, the column was opened for access. The screen or mold with the wet sheet of fibers was then removed from the column and transferred to the heated pressing device. The wet sheet of fibers was then pressed with controlled pressure and temperature until sufficiently dry. The dried sheet was then removed from the mold for testing.
For experimental plaques comprising regional fiber types, a partial charge or dose of each different fiber type was used in a modified process/apparatus. This modification was the insertion of a divider (
The resulting forming method for the experimental plaques was: To form sheets in the sheet former, after ensuring the drain valve was closed, the screen or mold was inserted, and the column was closed and latched. The divider was then inserted into the column bisecting the cylindrical volume in half and creating two semi-circular chambers as shown in
Depending on the positioning of the divider, a transition or interface region between the regions of fiber was created as shown in
1 available from Renewcell
2 available from Suzano America - Aracruz
3 available from GP - Alabama River
4 available from Vaggeryd
5available from SCA - Ostrand
6available from Iggesund
7available from Sustana
8available from Kemira
9available from Ingredion
The standard and experimental plaques were characterized according to the following test methods. All measurements were performed in a laboratory maintained at 23° C.±2° C. and 50%±2% relative humidity and test samples were conditioned in this environment for 2 hours prior to testing.
Plaque thickness was measured using a magna-micrometer device. Thickness measurements were taken of the standard plaques and of each of the regions of the experimental plaques. Thickness measurements were taken at 5 randomly selected points within each fiber region and averaged. Plaque weight was measured using a balance sensitive to 0.001 g. Five plaques were weighed together, and the resulting average weight (i.e. total weight divided by five) was recorded in TABLE 2.
Basis Weight was determined using the average mass as defined above (in grams) divided by the unit area of the plaques. As noted, the plaques were formed using a 159 mm diameter porous mold, so the plaques have a standard area of 200 cm2 or 0.02 m2. Basis weight was reported as g/m2 so basis weight was calculated as:
The samples were tested for tensile properties and surface roughness. The tensile properties (tensile strength, stretch and energy absorption) of the plaques were calculated from measured force and elongation values obtained using a constant rate of elongation test until the sample breaks. The test was run in accordance with compendial method Tappi T494—“Tensile Properties of Paper and Paperboard (Using constant rate of elongation apparatus)” with procedural specifics and modifications noted herein. Measurements were made on a constant rate of extension tensile tester using a load cell for which the forces measured were within 1% to 99% of the limit of the cell. The instrument used was the Instron Model 5965 using Bluehill Universal Software, both available from Instron (Norwood, MA), or equivalent.
The preparation of the test specimens and test procedure is described in the referenced Tappi method, with the following specific details. Samples were cut from the plaques for tensile testing. Samples were cut using a cutting die comprising a steel cutting rule to cut controlled sample sizes from the finished plaques. This sample cutting die cleanly and consistently cuts rectangular samples of 20 mm×60 mm using a swing arm die cutting press (or “clicker” press). The cut samples should be free from residual contaminants or other materials. Measurements were made with the long side of the sample parallel to the direction of the extension force.
The tensile tester was computer operated and programmed for a constant rate of extension uniaxial elongation to break as follows. Set the gauge length (test span) to 60 mm using a calibrated gauge block and zero the crosshead. Insert the test sample into the grips such that the long side was centered and parallel to the central pull axis of the tensile tester. Raise the crosshead at a rate of 0.8 mm/s (48 mm/min) until the test sample breaks, collecting force (N) and extension (mm) data at 100 Hz throughout the test.
The reported parameters including tensile strength, stretch and energy absorption were calculated by the software. Generally, these parameters were calculated as follows. Construct a graph of force (N) versus extension (mm). Read the maximum force (N) from the graph and record as Peak Force to the nearest 0.1 N. Read the extension at the maximum force (N) from the graph and record as Elongation at Break to the nearest 0.01 mm. From the graph, determine the point (z) where the tangent to the curve, with a slope equal to the maximum slope of the curve, intersects the elongation axis. Now calculate the area under the force vs elongation curve from point z up to the point of maximum force and report to the nearest 0.1 mJ.
Calculate the arithmetic mean Peak Force for all replicates and record respectively as Mean Peak Force to the nearest 0.1 N. Calculate the arithmetic mean Elongation at Break replicates and record respectively as Mean Elongation at Break to the nearest 0.01 mm. Calculate the arithmetic mean area under the force vs elongation curve for all replicates and record as Mean Area Under Curve to the nearest 0.1 mJ.
Tensile strength was calculated by dividing the Mean Peak Force (N) by the width of the test sample (20.0 mm). Calculate the tensile strength for the replicates and report as Tensile Strength to the nearest 0.1 kN/m.
Stretch at break was calculated by dividing the Mean Elongation at Break (mm) by the initial test length (test span) of 60 mm, and then multiplying by 100. Calculate the stretch at break for the replicates and report as Stretch at Break to the nearest percent.
Surface roughness was measured as line roughness using a contact type profilometer. The device used to generate the data in TABLE 1 was a Mitutoyo SurfTest SJ-310. This device uses an automated stylus device to traverse the surface of a sample over a given line path. The vertical deviation of the stylus was measured to within 1 um. The measurements taken within the linear path length of the stylus are then calculated and output. The outputted parameters include:
Ra—When dealing with the roughness profile, Ra is referred to as the arithmetic mean roughness height of the line of measurement. Arithmetical mean height indicates the average of the absolute value along the sampling length.
Rz—The maximum height of the profile indicates the absolute vertical distance between the maximum profile peak height and the maximum profile valley depth along the sampling length line. Rz is referred to as the maximum roughness.
Rq—Root mean square deviation indicates the root mean square along the sampling length. For the roughness profile, Rq is referred to as the root-mean-square roughness
Sample preparation was the same as that for measuring tensile properties. The sample was affixed to a flat surface prior to testing. The sample can be affixed to the flat surface by any suitable means such as gluing, clamping weighting and the like. For the data presented in Table 1 the sample was affixed to the flat surface by weighting.
The test results showed unexpected results, particularly in the characterization of the transition regions. When testing the multi-regional/experimental plaques (as described in TABLE 1) and comparing the results to the standard/single-region plaques, the results showed that regions comprising a common fiber composition generally shared the same properties as that fiber composition formed as a single-region/standard plaque. However, the transition regions between fiber regions may have properties that may be similar to one or the other of the adjacent single-region properties or may have properties that closer to an average of the adjacent single-region properties or may have properties that were substantially different from those of the adjacent single-regions.
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In another set of samples, also formed in regions as illustrated in
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The dimensions and values disclosed herein are not to be understood as being strictly limited to the exact numerical values recited. Instead, unless otherwise specified, each such dimension is intended to mean both the recited value and a functionally equivalent range surrounding that value. For example, a dimension disclosed as “40 mm” is intended to mean “about 40 mm.”
Every document cited herein, including any cross referenced or related patent or application and any patent application or patent to which this application claims priority or benefit thereof, is hereby incorporated herein by reference in its entirety unless expressly excluded or otherwise limited. The citation of any document is not an admission that it is prior art with respect to any invention disclosed or claimed herein or that it alone, or in any combination with any other reference or references, teaches, suggests or discloses any such invention. Further, to the extent that any meaning or definition of a term in this document conflicts with any meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to that term in this document shall govern.
While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.
| Number | Date | Country | |
|---|---|---|---|
| 63430435 | Dec 2022 | US |
