Patent Application
20250034810
Almond farming is a multi-billion-dollar global business. Commercial almond farming is typically carried out on large orchards consisting of many acres of almond trees. In 2020, the United States Department of Agriculture estimated that there are approximately 1.6 million acres of almond trees in California alone.
During the life cycle of an almond orchard, the almond trees naturally reach the end of their useful lives and need to be replaced. In general, almond trees hit a plateau for yield around 15 years and need to be ripped up and replaced with new trees after 20 years or so. The ripped up, spent almond trees result in a huge amount of agricultural waste that needs to be utilized or disposed of.
Historically, almond farmers regularly resorted to the burning of their spent almond tree waste, either on-site to dispose of it or as biomass feed for power plants. However, increasingly strict air quality regulations have largely reduced or stopped those practices, resulting in farmers now looking for other methods of utilizing or disposing of their almond tree waste. While some farmers have turned to the utilization of their spent almond tree waste as mulch for the subsequent almond tree crop, there remains a significant unmet need for beneficial uses for spent almond tree waste.
Despite the significant and ongoing need for beneficial uses for spent almond tree waste, almond trees have not been used in the manufacture of wood pulps, such as those used for the manufacture of paper products. In particular, due to the structure and composition of almond trees, they have heretofore not been seen as suitable for use in the production of wood pulps.
Traditional methods of manufacturing wood pulps involve the logging and chipping of trees prior to utilizing the chips in a pulping process. Logging systems (such as the cut-to-length system, the full-tree system, or the tree-length system) traditionally involve delimbing the trees to create logs from the tree trunks, making them amenable to further transport and processing. In addition, as the structure of bark is distinct and separable from the useful wood components of a tree, bark is considered to be a contaminant and is traditionally removed before pulping operations. Any residual bark is typically kept to a minimum, even in chemical processes such as the kraft pulping process, as any residual bark in the kraft process consumes a substantial amount of cooking liquor (which decreases effectiveness and increases cost), increases the amount of wood resins in the spent liquor (which causes issues in the recovery process), and can manifest as undesirable “dirt” in the finished product (an attribute consumers perceive as an indicator that the paper product is not itself clean and therefore undesirable for use in cleaning purposes).
Unfortunately, almond trees have a structure that renders them unsuitable for use in such traditional processes of delimbing and debarking. In particular, almond trees have short trunks and are primarily made up of their wide canopies of branches. Given the relatively low percentage of the total wood contained in the trunk as compared to the branches, delimbing almond trees to obtain trunk logs in the traditional manner for use in pulping is not economically viable or practical. Neither is it economical or practical to debark each of the large number of branches within the canopy prior to chipping. For at least these reasons, almond trees have not been understood as practical or useful in the production of wood pulps.
It has surprisingly been discovered that whole almond trees may be utilized in the kraft pulping process, without need to delimb or substantially debark the tree first. Without wishing to be bound by theory, it is believed that this surprising discovery may be related, at least in part, to the structure of almond bark as compared to the bark of traditional forest trees. In particular, the bark of almond trees is much thinner than forest trees, with a morphology that is believed to lend itself to dissolution in the kraft pulping process without a disproportionate increase in the requirement of cooking liquor, without a disproportionate increase in the amount of wood resins in the spent liquor, and without a disproportionate increase in residual “dirt” that results from the presence of the bark of traditional forest trees. The present disclosure thus describes a new and beneficial solution for the previously unmet need of repurposing spent almond orchard waste in the manufacture of kraft wood pulps.
Surprisingly, it has also been found that, not only is spent almond orchard waste suitable for use in the kraft pulping process as described herein, but the resulting almond pulps exhibit beneficial attributes making them useful as a partial or complete replacement for traditional forest wood pulps in the manufacture of paper products. Thus, this disclosure further provides a sustainable source of wood for wood pulps that can be used as a partial or complete replacement for traditional forest wood. The use of sustainable resources has become of particular importance to both environmentalists and consumers, particularly in the area of single-use consumer absorbent paper products such as bath tissue, facial tissue, paper towels, and wipes.
The new uses of almond orchard waste disclosed herein may also provide a significant economic and environmental benefit when used by pulp manufacturers located near almond orchards by reducing the need for shipping in traditional forest woods from more distant locations.
It has also surprisingly been found that the sustainable almond wood pulps described herein may be used in combination with other sustainable sources of cellulose (such as recycled fibers and/or sawdust) in the production of paper products with features comparable to current consumer paper products. As such, it is further disclosed herein paper products comprising sustainable almond wood pulp and at least one additional sustainable source of cellulose, wherein those sustainable sources are used as a partial or complete replacement for traditional forest wood.
Additional objects and advantages of the present disclosure will be set forth in part in the description which follows. The objects and advantages of the present disclosure will further be realized and attained by means of the elements and combinations particularly pointed out in the appended claims.
The foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the claims.
Methods of making almond wood pulps are disclosed herein, comprising obtaining almond wood from almond trees and subjecting the almond wood to kraft pulping to obtain an almond wood pulp. In some embodiments, the methods may comprise use of almond wood that has not been significantly delimbed and/or debarked. In some embodiments, the methods may further comprise obtaining the almond wood in the form of chips that may further optionally be subjected to screening subsequent to chipping. In some embodiments, the almond pulps may further be subjected to oxygen delignification and/or bleaching following kraft pulping.
Almond wood pulps are further disclosed herein, comprising at least about 2.5% by weight of wood fibers derived from almond trees. In some embodiments, the almond wood pulp may be a kraft pulp. In some embodiments, the almond wood pulps may comprise more than 2.5% by weight of wood fibers derived from almond trees, up to approximately 100%. In some embodiments, the almond wood pulp may be a bleached pulp. In some embodiments, the almond wood pulp may further comprise wood or cellulose fibers derived from at least one non-almond tree source, such as traditional hardwoods, softwoods, recycled pulps, and/or sawdusts. In some embodiments, the almond wood pulps may comprise beneficial properties, such as a low dirt count, high brightness, low coarseness, and the like, which make them suitable for downstream use in a variety of paper products.
Paper products are further disclosed herein, comprising at least about 2.5% by weight of wood fibers derived from almond trees. In some embodiments, the paper products may comprise more than 2.5% by weight of wood fibers derived from almond trees, up to approximately 100%. In some embodiments, the paper products may further comprise wood or cellulose fibers derived from at least one source other than almond trees, such as wood fibers from traditional forest hardwood and/or softwood trees. In some embodiments, the paper products may comprise wood or cellulose fibers derived from at least one additional sustainable source, for example recycled fibers and/or sawdust. In some embodiments, the paper products may be absorbent consumer paper products, such as tissue, towel, napkin, or wiper products.
The methods of making an almond wood pulp according to the present disclosure comprise obtaining almond wood from almond trees and subjecting the almond wood to kraft pulping to obtain an almond wood pulp.
While the present disclosure is not limited to any specific method of obtaining almond wood, almond orchard trees are typically uprooted and collected when they are deemed to have reached the end of their useful life. Standard practice in almond orchard removal is to pull out the entire tree including the root ball and lay the tree down in the field. Removal experts may then remove the root ball manually (e.g., with a chain saw) and prepare the tree for chipping.
According to some embodiments of the present disclosure, the almond trees are not significantly delimbed prior to chipping and the whole tree, including the branches, are fed into a chipper. This may be accomplished, for example, by notching the branches so that they fold inward when fed into a chipper. As used herein, the term “not significantly delimbed” means that the tree has not been subjected to a process that removes the majority of branches, even if some lesser amount of branches is removed prior to pulping, for example as a byproduct of otherwise handling and preparing the tree for chipping without the aim of substantially delimbing the tree.
Following chipping, the almond wood chips may be subjected to screening, such as with a rotary Trommel screen. During this process, oversized materials (such as poorly chipped materials) and/or undersized materials (such as debris, leaves, and loose bark) may be removed. The chips may further be subjected to additional chipping, grinding, and/or screening to obtain chips within desired size and chip quality specifications.
In some embodiments, the wood chips may be chipped and screened such that at least 70% by weight of the almond wood chips are between 2 and 10 mm, for example at least about 80%, at least about 90%, or at least about 95%. In some embodiments, from about 20% to about 30% by weight of the almond wood chips may be between about 2 mm and about 4 mm, for example from about 23% to about 27%. In some embodiments, from about 35% to about 45% by weight of the almond wood chips may be between about 4 mm and about 6 mm, for example from about 38% to about 42%. In some embodiments, from about 15% to about 25% by weight of the almond wood chips may be between about 6 mm and about 8 mm, for example from about 18% to about 22%. In some embodiments, from about 1% to about 10% by weight of the almond wood chips may be between about 8 mm and about 10 mm, for example from about 2.5% to about 7.5%. In some embodiments, less than about 10% by weight of the almond wood chips may be greater than about 10 mm, for example less than about 5%. In some embodiments, less than about 5% by weight of the almond wood chips may be less than a about 5 mm, for example less than about 2%, or less than about 1%.
According to some embodiments of the present disclosure, the almond trees are not significantly debarked before being subjected to kraft pulping. As used herein, the term “not significantly debarked” means that the tree has not been subjected to a process that removes the majority of the bark, even if some lesser amount of the bark is removed, for example as a byproduct of otherwise handling and preparing the tree for chipping, during chipping, and/or during screening without the aim of substantially debarking the tree.
In some embodiments, the almond wood that is subjected to kraft pulping comprises at least about 1% by weight bark content based on the total weight of the almond wood, for example at least about 2%, at least about 5%, at least about 7%, at least about 12%, or up to approximately the same amount of bark naturally found on the almond trees. Bark content may be determined by weighing a representative sample of almond wood to be pulped, removing the bark, and weighing the bark in the sample.
In some embodiments, the almond wood may be mixed with wood or cellulose from at least one source other than almond trees prior to kraft pulping (for example by mixing wood chips). The non-almond wood or cellulose may be derived from any common source, including wood or cotton. In some embodiments, the non-almond wood may be derived from traditional forest wood, for example softwood, hardwood, or mixtures thereof. In some embodiments, the non-almond wood may be derived from a softwood, such as pine, spruce, fir, hemlock, redwood, cedar, or mixtures thereof. In some embodiments, the non-almond wood may be derived from a hardwood, such as birch, poplar, basswood, eucalyptus, alder, maple, or mixtures thereof. In some embodiments, the non-almond wood or cellulose may be derived from recycled fibers and/or sawdust.
In embodiments where the almond wood has been mixed with wood or cellulose from at least one source other than almond trees prior to kraft pulping, the almond wood may comprise at least about 2.5% of the dry weight of the total wood and cellulose materials subjected to kraft pulping, for example at least about 10%, at least about 25%, at least about 50%, at least about 95%, or approximately 100%.
The methods of the present disclosure comprise subjecting the almond wood to kraft pulping to obtain an almond wood pulp. As used herein, the term “kraft pulping” means a pulping process that utilizes the combination of sodium hydroxide (NaOH) and sodium sulfide (Na2S) (referred to herein as “kraft liquor”). This process can also be referred to as “kraft cooking” or “kraft digesting.” In a standard kraft process, wood chips are combined with a hot alkaline aqueous solution of sodium hydroxide (NaOH) and sodium sulfide (Na2S) (referred to as “white” kraft liquor) in a digester. This process typically results in delignification of the wood, which refers to the process whereby lignin bound to the cellulose fiber is removed due to its high solubility in the alkaline kraft liquor. When the kraft process is complete, the resulting kraft pulp may be separated from the spent liquor (“black liquor”) which includes the used chemicals and dissolved lignin. Conventionally, the black liquor is burnt in a kraft recovery process to recover the sodium and sulfur chemicals for recycle for further use in the kraft pulping process.
Without wishing to be bound by theory, it is believed that the structure of almond bark surprisingly lends itself to dissolution in the kraft pulping process without a disproportionate increase in the requirement of cooking liquor and without a disproportionate increase in the amount of wood resins in the spent liquor. In contrast, significant amounts of bark from traditional forest woods like hardwood and softwoods can cause serious problems in the kraft process, making it noneconomical, impractical, or even impossible.
In some embodiments, the kraft pulping process may be carried out with a ratio of liters of kraft liquor to kilograms of dry wood of from about 3:1 to about 5:1, for example from about 3.5:1 to about 4.5:1, or from about 3.8:1 to about 4.2:1.
Depending upon the desired pulp attributes, the white liquor is added to the wood chips in sufficient quantity to provide a desired total alkali charge based on the dried weight of the wood. In some embodiments, the kraft pulping may be carried out with an effective alkali (defined as the total of NaOH+½ Na2S in g/L as Na2O) of from about 15% to about 25%, for example from about 18% to about 22%, or about 20%. Effective alkali may be measured according to TAPPI T-624 os-68.
The kraft pulping process may also be controlled by adjusting the sulfidity of the process (defined by the ratio of Na2S to the total of NaOH+Na2S in % on Na2O basis). In some embodiments, the kraft pulping may be carried out with a sulfidity of from about 25% to about 35%, for example from about 27% to about 29%, or about 28.5%. Sulfidity may be measured according TAPPI T-624 os-68.
The kraft pulping may also be controlled by adjusting the temperature and/or time conditions. In some embodiments, the kraft pulping may be carried out at a temperature between about 120° C. and about 200° C., for example from about 130° C. to about 180° C., or from about 155° C. to about 175° C. In some embodiments, the kraft pulping may be carried out for a time of from about 60 to about 150 minutes, for example from about 60 minutes to about 180 minutes, or from about 90 to about 120 minutes.
The kraft pulping may also be controlled by H-factor, which takes into account both the time and temperature of the process. H-factor may be calculated as follows (where t is time in minutes and T is temperature in Celsius):
In some embodiments, the kraft pulping may be carried out with an H-factor of from about 100 to about 1500, for example from about 200 to about 1000, from about 300 to about 750, or from about 300 to about 400.
The kraft process may be conducted until the almond wood pulp reaches a target kappa number. Kappa number may be used as an approximation for the amount of residual lignin in the pulp at the end of kraft pulping and can be determined according to TAPPI T236 cm-85. In some embodiments, the kraft process may be conducted until the almond wood pulp reaches a kappa number less than about 30, for example less than about 25, less than about from about 20, or less than about 15.
In some embodiments, the almond wood pulp may further be washed, de-knotted, and/or screened at the end of the kraft cooking process.
In some embodiments, the almond wood pulp may be subjected to an oxygen delignification process following the kraft cooking process. Oxygen delignification generally further reduces the lignin content and improves the effectiveness of any subsequent bleaching sequence. Oxygen delignification can be performed by any method known to those of ordinary skill in the art. In some embodiments, the almond wood pulp is not further subjected to oxygen delignification after pulping. In some embodiments, the almond wood pulp is subject to oxygen delignification after kraft pulping.
In some embodiments, the almond wood pulp is not further subjected to bleaching after pulping. In some embodiments, the almond wood pulp is subject to bleaching after kraft pulping. In some embodiments, the almond wood pulp is subject to both oxygen delignification and bleaching after kraft pulping.
Bleaching of wood pulp is generally conducted with the aim of selectively increasing the whiteness and/or brightness of the pulp, typically by further removing lignin and other impurities. Bleaching of chemical pulps, such as Kraft pulps, generally requires several different bleaching stages to achieve a desired whiteness and/or brightness with good selectivity. The almond wood pulps disclosed herein may be subjected to any known bleaching processes after pulping. In some embodiments, the bleaching process may be a multi-stage bleaching process, for example a three-, four-, or five-stage bleaching process. In some embodiments, the multi-stage bleaching process may comprise both alkaline and acidic bleaching stages, for example alternating alkaline and acidic bleaching stages. This alternation is believed to aid in the removal of impurities generated in the bleaching sequence, for example, by solubilizing the products of lignin breakdown.
Common bleaching stages that may be utilized according to the present disclosure include acidic “D” bleaching stages comprising treatment with chlorine dioxide and alkaline extraction “E” bleaching stages. For example, multi-stage bleaching processes according to the present disclosure may include D0-E-D1, D0-E-D1-E, or D0-E-D1-E-D2 bleaching sequences. The alkaline extraction “E” stages may optionally include oxygen and/or peroxide.
In some embodiments, the bleaching process may be conducted under conditions to target a final ISO brightness of the almond pulp. In some embodiments, the almond pulp may be bleached until an ISO brightness of at least about 80%, such as at least about 85%, at least about 87%, or at least about 90%, for example ranging from about 85 to about 95%, or from about 87% to about 93%. Brightness may be determined according to TAPPI T525-om02. In some embodiments, the final ISO brightness may be achieved without the use of optical brightening agents. In some embodiments, an optical brightening agent can be added to further increase the ISO brightness of the bleached almond pulp above 95%.
In some embodiments, the bleaching process may be conducted under conditions to target a final viscosity of the almond wood pulp. In some embodiments, the almond wood pulp may be bleached until a viscosity of less than about 30 cP, for example, less than about 25 cP, less than about from about 20 cP, or less than about 15 cP. Viscosity may be measured according to TAPPI T230-om13.
In some embodiments, the bleaching process may be conducted under conditions to target a final kappa of the almond wood pulp. In some embodiments, the almond wood pulp may be bleached until a kappa number less than about 10, for example less than about 5, or less than about 2.
Dirt count is a numerical estimation of the cleanliness of a pulp or paper in terms of the quantity of dirt, specks, or marks. Consumers tend to perceive the presence of dirt as an indicator that the paper itself is not clean and therefore undesirable for use in cleaning purposes, particularly those dirt particles with a size larger than about 0.04 mm2. Without wishing to be bound by theory, it is believed that the structure of almond bark surprisingly lends itself to dissolution in the kraft pulping process and/or the bleaching process, resulting in an almond wood pulp without a disproportionate increase in the level of residual “dirt” compared to pulps derived from traditional forest trees that are pulped and bleached without bark.
In some embodiments, the almond wood pulps disclosed herein may comprise a dirt count from 0.02-0.04 mm2 of less than about 30 ppm, for example less than about 20 ppm, less than about 15 ppm, or less than about 10 ppm. Dirt particles >0.04 mm2 are generally perceptible to the human eye and can be used as a measure of the consumer's perception of the cleanliness of the pulp. In some embodiments, the almond wood pulps disclosed herein may comprise a dirt count >0.04 mm2 of less than about 40 ppm, for example less than about 30 ppm, less than about 20 ppm, or less than about 15 ppm. Dirt count may be determined according to TAPPI T-213 om-06.
Coarseness is a measure of the average weight of fiber per unit length. In general, an increase in coarseness corresponds to a decrease in perceived softness. As such, it may be desirable to have a pulp with a low coarseness. In some embodiments, the almond wood pulps disclosed herein may comprise a coarseness of less than about 8 mg/100 m, for example less than about 7 mg/100 m, less than about 6 mg/100 m, or less than about 5 mg/100 m. Fiber coarseness may be determined with a Fiber Quality Analyzer (FQA). A small amount of the basesheet or finished product is placed in a temperature & humidity-controlled space for 12+ hours. A small portion of the basesheet or finished product is weighed out on a 5-place balance, then the fibers are dispersed using an ultrasonic disintegrator. The sample is further diluted, and a weighed portion is run thru the FQA. The weight of the sample seen by the FQA is used to calculate coarseness, which is expressed as mg/100 m.
In some embodiments, the almond wood pulps disclosed herein may comprise a tensile strength of at least about 1 kg/15 mm, for example from about 1 to about 10 kg/15 mm, from about 2 to about 5 kg/15 mm or from about 3 to about 4 kg/15 mm. Tensile strength of the almond wood pulp may be measured using 1.2 g unrefined handsheets according to TAPPI T205 sp-02.
Further disclosed herein are paper products comprising wood fibers derived from almond trees. The paper products according to the present disclosure comprise at least about 2.5% by weight of wood fibers derived from almond trees. In some embodiments, the paper products of the present disclosure may comprise at least about 10% by weight of wood fibers derived from almond trees, for example at least about 25%, at least about 50%, at least about 95%, or approximately 100%.
In some embodiments, the paper products may further comprise wood or cellulose fibers derived from at least one source other than almond trees. The non-almond wood or cellulose may be derived from any common source, including wood or cotton. In some embodiments, the non-almond wood may be derived from traditional forest wood, for example softwood, hardwood, or mixtures thereof. In some embodiments, the non-almond wood may be derived from a softwood, such as pine, spruce, fir, hemlock, redwood, cedar, or mixtures thereof. In some embodiments, the non-almond wood may be derived from a hardwood, such as birch, poplar, basswood, eucalyptus, alder, maple, or mixtures thereof. In some embodiments, the products of the present disclosure may also include synthetic fibers as desired for the end product.
In some embodiments, the non-almond wood or cellulose fibers may be derived from other sustainable sources, such as recycled fibers and/or sawdust. Recycled (or secondary) fibers may be categorized broadly into two types: post-consumer fibers and pre-consumer fibers. Post-consumer recycled fibers are those that have passed through their original end-usage as a consumer item, for example waste paper, paperboard, and/or fibrous materials from retail stores, office buildings homes, and the like. Pre-consumer recycled fibers are waste products from other processes that can be utilized in a beneficial way, for example trimming and cutting waste from paper mills, manufacturing waste, butt rolls, mill wrappers, and rejected unused stock, or obsolete or unused inventories from manufacturers, merchants, wholesalers, and the like. In some embodiments, the paper products described herein may comprise wood fibers derived from almond trees and at least one source of wood fibers other than almond trees chosen from at least one of post-consumer recycled fibers, pre-consumer recycled fibers, and mixtures thereof.
The U.S. Department of Commerce has categorized five particular types of recycled fibers: (1) “mixed paper” fibers (including fibers recycled from items such as office waste, discarded mail, telephone books, paperboard, magazines, and catalogs, as well as boxboard cuttings and mill wrappers), (2) “old newspaper” fibers (ONP), (3) “old corrugated containers” fibers (OCC), (4) “pulp substitute” fibers (including fibers recycled from unprinted paper and board that has not been coated, printed, or adulterated, for example tabulating cards, white and semi-bleached sheets, or cuttings, shavings, or trim from paper mills or print shops), and (5) “high-grade deinked” fibers (including fibers recycled from letterhead, copier paper, envelopes, and printer/convertor scrap that has gone through the printing process and subjected to deinking). In some embodiments, the paper products described herein may comprise wood fibers derived from almond trees and wood or cellulose fibers derived from at least one source other than almond trees chosen from at least one of mixed paper, old newspaper (ONP), old corrugated containers (OCC), pulp substitutes, high-grade deinked fibers, and mixtures thereof.
Sawdust is another sustainable source of wood fibers that may be utilized in some embodiments of the present disclosure. Sawdust is generated, for example, as a by-product of the production of lumber and is often used in low value applications such as inefficient mass burning for disposal. In some embodiments, the paper products described herein may comprise wood fibers derived from almond trees and at least one sawdust derived from a source other than almond trees.
In some embodiments, the paper products of the present disclosure may comprise at least 10% by weight of wood or cellulose fibers derived from sustainable sources (including at least almond wood fibers, recycled fibers, sawdusts, and mixtures thereof), for example at least about 25%, at least about 40%, at least about 50%, at least about 60%, at least about 75%, at least about 95%, or approximately 100%.
In some embodiments, the paper products of the present disclosure may comprise (i) at least about 10% by weight of wood fibers derived from almond trees and (ii) at least about 10% by weight of wood fibers derived from at least one of recycled fibers, non-almond wood sawdust, or mixtures thereof, for example at least about 25%, at least about 40%, at least about 50%, at least about 75%, or approximately 90%.
In some embodiments, the paper products of the present disclosure may comprise (i) at least about 25% by weight of wood fibers derived from almond trees and (ii) at least about 10% by weight of wood fibers derived from at least one of recycled fibers, non-almond wood sawdust, or mixtures thereof, for example at least about 25%, at least about 40%, at least about 50%, at least about 60%, or approximately 75%.
In some embodiments, the paper products of the present disclosure may comprise (i) at least about 40% by weight of wood fibers derived from almond trees and (ii) at least about 10% by weight of wood fibers derived from at least one of recycled fibers, non-almond wood sawdust, or mixtures thereof, for example at least about 25%, at least about 40%, or approximately 60%.
In some embodiments, the paper products of the present disclosure may comprise (i) at least about 60% by weight of wood fibers derived from almond trees and (ii) at least about 10% by weight of wood fibers derived from at least one of recycled fibers, non-almond wood sawdust, or mixtures thereof, for example at least about 25%, or approximately 40%.
In some embodiments, the paper products of the present disclosure may comprise (i) at least about 75% by weight of wood fibers derived from almond trees and (ii) at least about 10% by weight of wood fibers derived from at least one of recycled fibers, non-almond wood sawdust, or mixtures thereof, for example at least about 15%, or approximately 25%.
In some embodiments, the paper products according to the present disclosure may be manufactured on a papermaking machine. In a conventional papermaking machine, the wood and/or cellulose fibers may be included in a furnish in a headbox where the fibers can be admixed with water (and optionally chemical additives as appropriate) before being deposited onto a forming wire to form a nascent web. The nascent web may further be dewatered to form a “base sheet” or “ply.” The papermaking process and method of dewatering according to the present disclosure can be any conventional papermaking method, including conventional wet press process (CWP), Through Air Drying (TAD), eTAD, Uncreped Through Air Drying (UCTAD), Conventional Wet Crepe (CWC), Conventional Dry Crepe (CDC), Advanced Tissue Molding System (ATMOS), Advantage New Tissue Technology (NTT), and the like. The paper products according to the present disclosure may further be creped or uncreped.
In a typical papermaking process, after drying, the base sheet is rolled and awaits converting. While converting operations are generally carried out on rolled (reeled) paper plies, converting operations may also be added directly to the end of a papermaking process or processes without being rolled up first. Converting refers to the process that changes or converts base sheets into final products. Typical converting in the area of paper products according to the present disclosure may include calendering, embossing, perforating, gluing, plying, slitting, rolling, and/or folding. The paper products disclosed herein may be subjected to any of the recognized converting operations that are readily apparent to the skilled artisan depending upon the type of end product that one is making.
The chemical additives for use in the papermaking process can be any known combination of papermaking chemicals. Such chemistries are readily understood by the skilled artisan and their selection will depend upon the type of end product that one is making. Papermaking chemicals include, for example, dry strength agents, wet strength agents, softeners and debonders, creping modifiers, sizing agents, optical brightening agents, retention agents, and the like.
In some embodiments comprising papermaking fibers derived from at least one source other than almond trees, the almond wood fibers and the non-almond wood fibers may be mixed together in the headbox of a papermaking machine before being deposited onto a forming wire. Accordingly, in some embodiments, the paper products of the present disclosure may comprise a base sheet comprising a substantially homogeneous composition of fibers throughout the base sheet.
In some embodiments comprising papermaking fibers derived from at least one source other than almond trees, the almond wood fibers and the non-almond wood fibers may be fed into separate chambers of a headbox before being deposited onto a forming wire in layers. Accordingly, in some embodiments, the paper products of the present disclosure may comprise a base sheet comprising a stratified composition of fibers throughout the thickness of the paper product, comprising at least one first layer near a first surface of the base sheet comprising a higher concentration of almond wood fibers than an at least one second layer near the opposite side of the base sheet. The transition between stratified layers needs not be immediate, but may include a transition area.
In some embodiments, the paper product can be a single-ply paper product. In some embodiments, the paper product can be a multi-ply paper product, for example a two-ply, three-ply, or four-ply paper product. The individual plies may be made from the same or different furnishes of papermaking fibers, resulting in plies with either substantially the same or different fiber compositions.
According to the present disclosure where the paper product is a multi-ply product, at least one of the plies must comprise wood fibers derived from almond trees such that the paper product comprises at least about 2.5% by weight of wood fibers derived from almond trees. In some embodiments, the paper product can be a multi-ply product wherein only one ply comprises wood fibers derived from almond trees. In some embodiments, the paper product can be a multi-ply product wherein more than one may comprise wood fibers derived from almond trees. In some embodiments, the paper product can be a multi-ply product wherein each of the plies may comprise wood fibers derived from almond trees.
In some embodiments where the paper product is a multi-ply product, the fibrous composition of each ply may be substantially the same. In some embodiments where the paper product is a multi-ply product, the fibrous composition of at least one ply may be different from at least one other ply.
As used herein, the term “paper product” refers to any product comprising at least 50% by weight of wood or cellulosic fibers, for example at least about 60%, at least about 75%, at least about 95%, or approximately 100%.
In some embodiments, the paper product may be an absorbent consumer product. In some embodiments, the paper product may be a bath tissue. In some embodiments, the paper product may be a facial tissue. In some embodiments, the paper product may be a towel, such as a paper towel. In some embodiments, the paper product may be a napkin. In some embodiments, the paper product may be a wiper.
Almond orchard trees were uprooted, their root balls were removed, and the branches were notched with a saw so they would fold inward when the trees were fed into a whole tree chipper. The trees were not delimbed or debarked before being fed into the chipper. The whole tree chips were screened using a rotary Trommel screen to remove branches and large chunks of woody materials and debris. Accepts were passed through the screen while large materials were retained and rejected from the Trommel. The accepts from the Trommel screen were then put in a tub grinder with a 2″×2″ screen to reduce size and knock off some of the loose bark. The loose bark, debris, leaves, and other materials smaller than the screen size were passed through and removed as rejects.
The bark content of the resulting almond wood chips was roughly estimated with a fiber lab chip thickness classifier with slotted screens. For the rough estimate, any wood chip that had at least some bark content was weighed, and the entire chip weight was counted as bark. As such, this rough method likely somewhat overestimated the bark content. The results are shown in Table 1. In order to accurately estimate the bark content, it would be necessary to remove the bark and to weigh the bark separately.
The almond wood chips were subjected to kraft pulping in a laboratory kraft digester. 1 kg of the almond wood chips on a dry basis was used with a liquor:wood (L:W) ratio of 4:1 on a water basis (i.e., 1 L is equivalent to 1 kg of water or dry wood). The kraft pulping conditions utilized are shown in Table 2.
For comparison, red alder hardwood chips were pulped under the same conditions. An evaluation of two samples of each of the resultant kraft pulps is shown in Table 3.
Kraft almond wood pulp prepared according to Example 1 was bleached in the lab using a three-stage D0-Eop-D1 bleaching process at the conditions shown in Table 4. The amount of chemicals used in the D1 stage was varied in samples A, B, and C. Depending upon the amount of bleaching chemical used in the D1 stage, the brightness of the resulting bleached almond wood pulps varied from 82-86 ISO brightness. With increased severity of bleaching conditions, it is expected that brightnesses over 86 can readily be achieved.
Dirt count was evaluated following the Eop stage, as well as the D1 stage for each of the three samples, as well as for a comparative sample of bleached red alder. The results are shown in Table 5.
As can be seen from Table 5, the dirt count of the bleached kraft almond wood pulps was slightly elevated compared to the alder pulp, but within the natural deviation of the incumbent wood. This demonstrates that almond wood pulps may surprisingly be used as a partial or complete replacement for traditional forest wood pulps, such as red alder, without a significant increase in dirt content and with comparable brightness.
A full-scale mill trial was conducted, wherein a mixture of 5% by weight almond wood and 95% by weight red alder was subjected to kraft pulping and D0-Ep-D1 bleaching and compared to a bleached kraft pulp made from 100% red alder (0% almond wood) at the same conditions. Dirt count measurements were taken following the Ep bleaching stage after the washer and rewasher, as well as after the D1 bleaching stage The results are shown in Table 6:
As can be seen from Table 6, the dirt counts in the 5% almond wood pulp was similar to the comparison 0% almond wood pulp, with the dirt count >0.04 being 12.8 for the 5% almond wood pulp after the final bleaching stage compared to 13.0 for the 0% almond wood pulp. This full-scale mill trial demonstrated that addition of 5% almond pulp to an alder wood pulp did not increase the dirt content, indicating that the combination of kraft pulping and bleaching chemicals was successfully able to remove the excess bark in the almond wood pulp entering the pulping process.
Absorbent consumer paper products were made on a pilot papermaking machine to evaluate the utilization of almond wood pulps on finished paper product properties. Furnishes were prepared from mixtures of pulps according to Tables 7 with chemical addition and properties indicated in Table 8. “Almond” indicates a bleached kraft pulp made from 100% almond wood. “Red Alder” indicates a bleached kraft pulp made from 100% red alder hardwood. “Eucalyptus” indicates a bleached kraft pulp made from 100% eucalyptus hardwood. “Softwood” indicates a bleached kraft pulp made from 100% Douglas fir and hemlock softwood. “Recycled” indicates a high grade deinked recycled fiber. “Sawdust” indicates a bleached kraft pulp made from 100% softwood sawdust. The pulps were either mixed and deposited onto a forming wire to form homogonous plies or from separate chambers of a headbox to form stratified plies. Where stratified plies were formed, “YL” indicates the furnish laid on the side that contacted the Yankee dryer, while “AL” indicates the furnish laid on the opposing air side.
The physical properties of finished products made from the samples in Tables 8 and 8 are shown in Table 9.
Control samples 1A/B, 3A/B, and 5 are considered premium products, having a target softness of 18.8. As can be seen from Table 8, it has surprisingly been demonstrated that paper products made incorporating almond wood pulps were able to achieve comparable properties, including softness, to make them suitable as a direct replacement, at least in part, for traditional forest hardwood pulps like eucalyptus. In fact, Samples 6-11 are examples of premium products made from 100% sustainable fibers, including almond wood pulp and either recycled fibers or sawdust, while maintaining properties comparable to premium products made with traditional forest hardwood pulps like eucalyptus.
The foregoing examples demonstrate the unexpected benefits of one or more of decrease costs, decreased environmental impacts, and/or increased utilization of sustainable almond orchard waste in the manufacture of premium bleached kraft pulps and absorbent consumer products.
A number of embodiments have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the disclosure. Accordingly, other embodiments are within the scope of the following claims.
This application claims the benefit of U.S. Provisional Application No. 63/515,705, filed Jul. 26, 2023, the contents of which are incorporated herein by reference. This disclosure relates to methods of manufacturing wood pulp from almond orchard trees, almond wood pulps, and sustainable paper products made therefrom (such as absorbent consumer paper products). As detailed herein, it has surprisingly been found that it is possible to manufacture wood pulp from almond orchard trees using the kraft process, resulting in almond wood pulps exhibiting beneficial attributes making them useful as a partial or complete replacement for traditional forest wood pulps in the manufacture of paper products.
| Number | Date | Country | |
|---|---|---|---|
| 63515705 | Jul 2023 | US |
