WO2019118987A1

WO2019118987A1 - Degradable absorbent polymers and uses thereof

Info

Publication number: WO2019118987A1
Application number: PCT/US2018/066093
Authority: WO
Inventors: Jeffrey BATES; Amber BARRON; Ashlea PATTERSON; Sarai PATTERSON; Kathleen Bailey; Aruna DHUNGEL; Alicia DIBBLE
Original assignee: Shero Llp
Priority date: 2017-12-15
Filing date: 2018-12-17
Publication date: 2019-06-20

Abstract

A biodegradable personal hygiene product made from a biologic super absorbent polymer, and a method and device for making the product by pressing the material into an appropriate shape are disclosed.

Description

TITLE: DEGRADABLE ABSORBENT POLYMERS AND USES THEREOF

CROSS REFERENCE TO RELATED APPLICATION

[0001] This non-provisional patent application claims priority to, and the benefit of,

U.S. Provisional Patent Application No. 62/599,473, filed on December 15, 2017, entitled “BIODEGRADABLE FEMININE HYGIENE PADS AND PRESS,” which is incorporated herein by reference in its entirety. FIELD OF THE INVENTION

[0002] The present disclosure relates generally to biodegradable and/or degradable personal hygiene products and, more specifically, to biologic, biodegradable, and/or degradable super absorbent polymers for use in feminine hygiene pads, and systems and methods of making the same.

BACKGROUND

[0003] Products such as disposable baby diapers and feminine pads have improved convenience and quality of life in the developed world. Consumers have embraced them— industry sales of disposable absorbent products are in the tens of billions of dollars.

[0004] Yet, there are pressing environmental and health reasons to reduce the negative impacts of conventional disposable absorbent products. Conventional products contain synthetic materials, such as plastic film, rayon fibers and petrochemical-based super absorbent polymers, like sodium polyacrylate. These materials can take tens or even hundreds of years to decompose in landfills and comprise a significant portion of total municipal solid waste generated in the United States.

[0005] Conventional disposable absorbent products are problematic for various reasons. Certain developing countries are currently struggling with unsustainable waste management. In these nations, population growth, urbanization and growing affluence are expected to increase consumption of all kinds, including for disposable products, exacerbating the challenges of solid waste disposal. In the United States and abroad, plastic products often make their way into waterways and oceans, becoming part of a large plastic marine debris problem. Some of these plastics break down into smaller microplastic particles. These microparticles have the potential to enter aquatic food chains, causing as-yet unknown impacts on fish and sea life. Human health can also be affected by conventional disposable absorbent products, particularly when they come in direct contact with mucous membranes. These membranes are more permeable than skin, and can uptake chemicals into the body.

[0006] Despite these drawbacks, lack of access to disposable absorbent products can impact human development. In the United States, for example, lower income children without access to disposable diapers are sometimes unable to attend preschool, making it more difficult for their parents to work. And lack of access to disposable feminine hygiene products can disrupt clean water supplies and hamper the economic opportunities of women and girls in the developing world. While limited natural-material absorbent products are available in certain markets, these products may not be fully degradable, and may be bulky, uncomfortable, and/or less effective than synthetic alternatives.

[0007] For all these reasons, there is a need for disposable absorbent products that are biodegradable and/or degradable and made from biologic materials.

SUMMARY

[0008] A personal hygiene product is disclosed herein, the personal hygiene product comprising a top layer, a transfer layer, an absorbent layer, and a barrier layer, wherein at least one of the top layer, the transfer layer, the absorbent layer, and the barrier layer comprise a biodegradable material. [0009] In various embodiments, the biodegradable material comprises at least one of banana leaves, rice, cotton, wood fibers, agarose, agar, carrageenan, polyvinyl alcohol, sodium silicate, polyhydroxybutyrate, and polyhydroxyalkanoate. In various embodiments, the personal hygiene product is fully biodegradable. In various embodiments, the absorbent layer comprises a hydrogel. In various embodiments, a particulate is dispersed in the hydrogel. In various embodiments, the particulate comprises at least one of cotton or wood. In various embodiments, the cotton comprises boiled cotton.

[0010] A hydrogel sheet for use in a personal hygiene product is disclosed herein, the hydrogel comprising at least one of rice, agarose, agar, carrageenan, polyvinyl alcohol, sodium silicate, polyhydroxybutyrate, and polyhydroxyalkanoate. In various embodiments, the hydrogel comprises a transfer material, wherein the transfer material comprises at least one of cotton, wood fluff pulp, sawdust, wool, flax fiber, hemp fiber, coconut fiber, bamboo fiber, jute fiber, banana fiber, water lotus fiber, com, sugarcane, oat straw, rye, barley, or polyvinyl alcohol.

[0011] In various embodiments, the hydrogel sheet further comprises an ionic salt. In various embodiments, the ionic salt comprises at least one of calcium chloride, calcium hydroxide, potassium chloride, potassium hydroxide, sodium chloride and sodium hydroxide, magnesium chloride and magnesium hydroxide. In various embodiments, fibers of the transfer material randomly oriented. In various embodiments, the hydrogel sheet comprises a depth of between 10 um and 1000 um. In various embodiments, the hydrogel sheet comprises a textured pattern. In various embodiments, the hydrogel sheet defines a plurality of apertures extending through the hydrogel sheet. In various embodiments, the hydrogel sheet comprises 0.5% to 25% kappa carrageenan by weight and 75% to 99.5% cotton by weight. In various embodiments, the hydrogel sheet comprises 0.5% to 25% kappa carrageenan by weight and 75% to 99.5% wood fluff pulp by weight. In various embodiments, the hydrogel sheet comprises between 0.1% and 70% kappa carrageenan by weight.

[0012] A personal hygiene product is disclosed herein, the personal hygiene product comprising a top layer coupled to an absorbent layer by an adhesive, and a barrier layer coupled to the absorbent layer by the adhesive, wherein the personal hygiene product is fully degradable.

[0013] In various embodiments, the absorbent layer comprises a superabsorbent polymer integrated with a transfer material, wherein the superabsorbent polymer comprises at least one of rice, agarose, agar, carrageenan, polyvinyl alcohol, sodium silicate, polyhydroxy butyrate, and polyhydroxy alkanoate, and wherein the transfer materials comprises at least one of cotton, wood, wool, flax fibers, hemp fibers, coconut fiber, bamboo fiber, jute fiber, banana fiber, water lotus fiber, sawdust. In various embodiments, the top layer comprises a porous or semi-permeable woven or nonwoven cloth comprising at least one of cotton, polylactic acid, or cellulose-based material. In various embodiments, the barrier layer comprises a biodegradable bioplastic comprising at least one of cellulose, starch, or vegetable oil.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The accompanying drawings are included to provide a further understanding of the present disclosure and are incorporated in, and constitute a part of, this specification, illustrate various embodiments, and together with the description, serve to explain the principles of the disclosure.

[0015] Figure 1 illustrates an exploded view of a personal hygiene product, in accordance with various embodiments.

[0016] Figure 2 illustrates a top view of the packaging of a personal hygiene product in a folded configuration, in accordance with various embodiments. [0017] Figure 3 illustrates a personal hygiene product press.

[0018] Figure 4 illustrates absorbency of various absorbent materials, in accordance with various embodiments.

[0019] Figure 5 illustrates absorbency of various absorbent materials, in accordance with various embodiments.

[0020] Figure 6 illustrates absorbency of various hydrogels comprising ionic salts, in accordance with various embodiments.

[0021] Figure 7 illustrates absorbency of cotton under various circumstances, in accordance with various embodiments.

DETAILED DESCRIPTION

[0022] The detailed description of various embodiments herein makes reference to the accompanying drawings, which show various embodiments by way of illustration. While these various embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, it should be understood that other embodiments may be realized and that logical, chemical, and mechanical changes may be made without departing from the spirit and scope of the disclosure. Thus, the detailed description herein is presented for purposes of illustration only and not of limitation.

[0023] For example, the steps recited in any of the method or process descriptions may be executed in any order and are not necessarily limited to the order presented. Furthermore, any reference to singular includes plural embodiments, and any reference to more than one component or step may include a singular embodiment or step. Also, any reference to attached, fixed, connected, or the like may include permanent, removable, temporary, partial, full, and/or any other possible attachment option. Additionally, any reference to without contact (or similar phrases) may also include reduced contact or minimal contact. [0024] For example, in the context of the present disclosure, devices and methods may find particular use in connection with feminine hygiene products. However, various aspects of the disclosed embodiments may be adapted for use in infant diapers, adult diapers, incontinence products, panty liners, tampons, other personal hygiene products, healthcare products, pet care products, food packaging and products, or any other products configured to absorb fluid. As such, numerous applications of the present disclosure may be realized.

[0025] As used herein, the term“biodegradable” refers to decomposition of a material that results from an attack by microorganisms that metabolize the material for nutrients and energy. Under standard aerobic conditions, materials described in this filing as degradable or biodegradable would be expected to decompose in two years or less.

[0026] As used herein, the term“biologic” refers to materials that are isolated from a variety of natural sources, for example, plant, algae, microorganism or animal. These materials may be processed into useable form by a variety of methods.

[0027] As used herein, the term“degradable” refers to a material that can be broken down into biologically nutritive compounds through chemical, physical or biological processes.

[0028] As used herein, the term“hydrocolloids” means long chain polysaccharides with an affinity for binging water molecules that may form viscous dispersions and/or gels when dispersed in water.

[0029] As used herein, the term“feminine hygiene pads” refers to pads of any size or absorbency level, including panty liners, which are designed to capture menstrual flow.

[0030] As used herein, the term“personal hygiene product” refers generally to disposable absorbent products including, without limitation, infant diapers, adult diapers, incontinence products, panty liners, tampons, other personal hygiene products, healthcare products, pet care products, food packaging and products, or any other products configured to absorb fluid.

[0031] As used herein, the terms“super absorbent polymer,”“SAP,” and“hydrogel” refer to hydrocolloids or biologic absorbent polymers in any form, alone or in combination with other powdered, crystalline, and/or flaked materials, that are configured to absorb fluid, allow fluid transfer within the hydrogel, and prevent or minimize fluid desorption under pressure.

[0032] In various embodiments, a personal hygiene product may comprise an absorbent, biodegradable and/or degradable material placed into an outer shell. The personal hygiene product may comprise a feminine hygiene pad. In various embodiments, the absorbent, biodegradable and/or degradable material may comprise an SAP. In various embodiments, the feminine hygiene pad may be made from readily available and/or naturally-occurring material that is absorbent, such as banana leaves, rice, cotton, wood fibers, and/or materials derived from any such readily available and/or naturally-occurring materials. Use of such readily available and/or naturally-occurring materials may facilitate use, production, or availability of the personal hygiene pad in geographically remote and/or economically disadvantaged populations.

[0033] In various embodiments, the personal hygiene product comprises one or more biodegradable and/or degradable materials. The personal hygiene product may comprise a biodegradable and/or degradable material that will decompose quickly. For example, in various embodiments, the biodegradable and/or degradable material may substantially decompose in less than one year. In various embodiments, the biodegradable and/or degradable material may substantially decompose in less than 6 months. In various embodiments, the biodegradable and/or degradable material may substantially decompose in less than 2 months. Rapid decomposition of the biodegradable and/or degradable material may limit human, vector, and environmental exposure to biohazardous material and/or materials harmful to the environment. Rapid decomposition of the biodegradable and/or degradable material may decrease or minimize the atraction of pests or vectors to the personal hygiene product. Rapid decomposition of the biodegradable and/or degradable material may decrease or minimize the occurrence of disease propagation by vectors exposed to the personal hygiene product.

[0034] With reference to Figure 1 , in various embodiments, a personal hygiene product

400 comprises two or more layers. The two or more layers may comprise at least one absorbent, biodegradable and/or degradable material and an outer shell. In various embodiments, the two or more layers may comprise a top layer 408, a transfer layer 406, an absorbent layer 404, and/or a barrier layer 402. Layers of the personal hygiene product may be configured to protect clothing from bodily fluid, wick fluid and moisture away from a user’s body without abrading or irritating it, collect and/or absorb bodily fluid.

[0035] In various embodiments, top layer 408 is configured to be in contact with a user of the personal hygiene product. Top layer 408 may comprise a porous or semi-permeable nonwoven sheet. Top layer 408 may comprise a hydrophobic or semi-hydrophobic material to promote fluid flow through top layer 408, instead of saturating and causing discomfort to the user. Top layer 408 may comprise polylactic acid, coton and/or another cellulose-based woven or nonwoven sheet. In various embodiments, the cotton may be boiled in water before use in the personal hygiene product, to overcome its natural hydrophobic qualities. In various embodiments, the coton is boiled in hydrogen peroxide to overcoming its natural hydrophobic qualities. Boiling in hydrogen peroxide may be more environmentally conscious than traditional treatments with bleach because no polluting waste results from boiling coton in hydrogen peroxide. In various embodiments, top layer 408 may comprise organic coton, which may lack residual pesticides. However, top layer 408 may comprise non-organic coton. In various embodiments, top layer 408 may be sterilized by boiling, exposure to ultraviolet light, and/or any other suitable means for sterilization prior to contact with the user’s body. [0036] In various embodiments, transfer layer 406 is disposed between top layer 408 and absorbent layer 404. Transfer layer 406 may be configured to wick fluid and/or moisture away from top layer 408 and to facilitate transfer of fluid and/or moisture to absorbent layer 404. In various embodiments, transfer layer 406 comprises cellulose fiber that has been shredded and packed in random fiber orientations. Microscopic capillaries may be disposed between packed fibers to promote fluid flow in all directions. Random fiber orientations may facilitate fluid flow in a direction away from top layer 408 and towards absorbent layer 404. Random fiber orientations may facilitate fluid flow in all directions so as to increase dispersion of fluid across a surface of absorbent layer 404. Stated differently, random fiber orientations may increase absorption of the personal hygiene product by using more of its surface area. In various embodiments, transfer layer 406 may comprise cotton, wood pulp, or another suitable cellulose-based or non-cellulose-based material.

[0037] Absorbent layer 404 may comprise a thin, lightweight, absorbent material and may be configured to absorb fluid readily and hold the fluid without leaking when force is exerted on the personal hygiene product. In various embodiments, absorbent layer 404 comprises a material that will not increase substantially in size in response to absorbing a fluid. In various embodiments, absorbent layer 404 may comprise a biodegradable and/or degradable hydrogel to increase absorbency. In various embodiments, absorbent layer 404 may be configured to absorb about 10 to about 20 times its weight in fluid.

[0038] In various embodiments, absorbent layer 404 may comprise one or more biologic-based hydrogels or super absorbent polymers (SAPs). Use of one or more SAPs may allow absorbent layer 404 to be configured with a slimmer product profile without materially decreasing the fluid absorbency, comfort or degradability of absorbent layer 404. Stated differently, absorbent layer 404 comprising one or more SAPs may comprise substantially the same depth as commercially-available, non-biodegradable personal hygiene products. In various embodiments, absorbent layer 404 may comprise a depth of about lOum to about lOOOum. In various embodiments, absorbent layer 404 may comprise a depth of about 25um to about l50um. In various embodiments, absorbent layer 404 may comprise a depth of about 50um to about lOOum. However, absorbent layer 404 may comprise any depth suitable for use in a personal hygiene product.

[0039] In various embodiments, the biodegradable and/or degradable hydrogel may comprise a brown-algae based hydrogel, agar, agarose, carrageenan, kappa carrageenan, or another polysaccharide polymer material extracted from seaweed. In various embodiments, the biodegradable and/or degradable hydrogel may be derived from rice. In various embodiments, the biodegradable and/or degradable hydrogel may comprise polyvinyl alcohol, sodium silicate, polyhydroxybutyrate, and/or polyhydroxyalkanoate.

[0040] In various embodiments, absorbent layer 404 may comprise a biodegradable and/or degradable hydrocolloid derived from at least one of a plant, microbe, or animal. The hydrocolloid may comprise or be derived from one or more of modified cellulose, microcrystalline cellulose, carbomethylcellulose, methylcellylose, hemicelluloses, mannans, galactomannans, gulcomannans, carob tree, locust bean gum, carob bean gum, the guar plant, guar gum, tara gum, senna gum, fenugreek gum, gum from tagua palm seeds, konjac glucomannan, fructans, inulins, roots or tubers of the family of plants Compositae or Liliacae, pectins, fruits, vegetables, food processing by-products such as apple pulp, citrus peels or sugarbeet pulp, exudate gums, acacia gum, gum Arabic, gum tragacanth, gum karaya, gum ghatti, mucilage gums, psyllium, yellow mustard, flax mucilage, alginates, brown seaweeds (Phaeophyceae), bacteria, Pseudomonas aeruginosa, Azobacter vinelandii, carrageenan, marine red algae of the Rhodophycaea class, including Chondrus crispus, Euchema cottoni, Euchema spinosum, Gigartina skottsbergi, or Iradaea laminarioides, agar, red-purple algae of the Rhodophyceae class, including Gracilaria or Gelidium, agarose, xanthan gum, Xanthomonas campestris, pullulan, fungi, including Aureobasidium or A. pullulans, gellan gum, Sphingomonas elodea, chitin, yeast, green, brown or red algae, insects, the shells of crustaceans, including shrimp, lobster or crab, hagfish slime, gelatin, collagen, or animal connective tissue.

[0041] In various embodiments, absorbent layer 404 comprises a biologic hydrocolloid and at least one transfer material. Transfer material may provide structure for absorbent layer 404, and/or may increase absorbency of the personal hygiene product. In various embodiments, transfer material to be combined with the SAP may include one or more of cotton, wood fluff pulp, sawdust, or other wood-derived materials. However, other biologic materials may be more readily available and cost effective for use in developing markets, and their use would increase the sustainability of the final product by using locally sourced materials. In various embodiments, transfer material may include wool, flax fibers, hemp fibers, coconut fiber, bamboo fiber, jute fiber, banana fiber, water lotus fiber, com, sugarcane, oat straw, rye, barley, or polyvinyl alcohol, among other absorbent biologic, biodegradable, and/or degradable materials and their derivatives.

[0042] In various embodiments, the hydrocolloid may comprise about 0.1% to about

70% by weight of absorbent layer 404. However, absorbent layer 404 may comprise any percent by weight of hydrocolloid suitable for use in a personal hygiene product. The relative proportions of hydrocolloid weight to absorbent layer weight may be determined in part by the desired absorbency of the chosen transfer material and the relative cost of materials. Ratios of SAP and transfer materials may also vary depending on the desired characteristics of the final product. Such characteristics may include the desired dimensions (size, shape, thickness) of the personal hygiene product, the type of fluid intended to be absorbed, the volume of fluid intended to be absorbed, the and desired weight and thinness of the product. [0043] In various embodiments, absorbent layer 404 may comprise kappa carrageenan and at least one of cotton or wood pulp. In various embodiments, kappa carrageenan may comprise between about 0.5% to about 25% by weight of absorbent layer 404 and cotton may comprise between about 75% to about 95% by weight of absorbent layer 404. In various embodiments, kappa carrageenan may comprise about 5% by weight of absorbent layer 404 and cotton may comprise about 95% by weight of absorbent layer 404. In various embodiments, kappa carrageenan may comprise between about 0.5% to about 25% by weight of absorbent layer 404 and wood pulp may comprise between about 75% to about 95% by weight of absorbent layer 404. In various embodiments, kappa carrageenan may comprise about 5% by weight of absorbent layer 404 and wood pulp may comprise about 95% by weight of absorbent layer 404. In various embodiments, such a ratio by weight may be suitable for use in feminine hygiene pads. However, absorbent layer 404 may comprise any suitable ratio of kappa carrageenan to at least one of cotton or wood pulp, and/or hydrocolloid to transfer material.

[0044] In various embodiments, the hydrogel may be produced by hydrating polymer crystals and/or other powdered, crystalline or flaked biodegradable and/or degradable materials in heated water and pouring the resulting mixture into a container of suitable size and shape for cooling and solidifying into a hydrogel. The hydrogel may be dehydrated prior to use in the personal hygiene product. In various embodiments, the dehydrated hydrogel is of suitable size, shape, and thickness for use in the personal hygiene product. However, the dehydrated hydrogel may be cut into any size, shape, and/or thickness desired. In various embodiments, the personal hygiene product comprises one sheet of hydrogel. However, any desired number of hydrogel sheets may be used to achieve a personal hygiene product with the desired absorbency, thickness, and weight. [0045] In various embodiments, the hydrogel may comprise perforations or apertures.

Such perforations or apertures may be configured to allow expansion of the hydrogel in response to absorption of fluid, while preventing or minimizing buckling, wrinkling, or bunching of absorbent layer 404. In various embodiments, the hydrogel may comprise a textured pattern. In such embodiments, a surface of the hydrogel may comprise a plurality of indentations and/or depressions. Such indentations and/or depressions may be arranged so as to create a pattern, for example, a waffle pattern. In various embodiments, the hydrogel may comprise one or more score lines. Score lines may allow the hydrogel to be folded and unfolded for packing and unpacking, respectively, of the personal hygiene product. In various embodiments, an absorbent material or particulate matter may be dispersed in the hydrogel. The absorbent material or particulate matter may comprise sawdust, wood, and/or any other suitably absorbent and biodegradable and/or degradable material.

[0046] In various embodiments, absorbent layer 404 may be configured to allow fluid transfer so as to become completely saturated. In various embodiments, other biodegradable and/or degradable non-hydrocolloid materials may be combined with one or more hydrocolloids to change the absorbency, cost profile or workability of the materials while maintaining the overall degradability of absorbent layer 404. In various embodiments, such non-hydrocolloid materials may include cellulose or its derivatives, including agricultural products or byproducts such as rice, tapioca, wheat, com, sugarcane, oat straw, rye and barley, polyvinyl alcohol, sodium silicate, polyhydroxybutyrate, or polyhydroxyalkanoate. In various embodiments, such non-hydrocolloid materials may be in powdered, flaked and/or crystalline form. In various embodiments, one or more ionic salts may be added to absorbent layer 404, including calcium chloride, calcium hydroxide, potassium chloride, potassium hydroxide, sodium chloride, sodium hydroxide, magnesium chloride, magnesium hydroxide or any other suitable ionic salt. [0047] With reference to Figure 1, in various embodiments, personal hygiene product

400 comprises a distinct transfer layer 406 and a distinct absorbent layer 404. However, in various embodiments, one or more transfer materials may be integrated within absorbent layer 404. By using only materials that are degradable, the absorbent layer 404 and/or transfer layer 406 would also be fully degradable.

[0048] Transfer materials may be prepared various ways prior to incorporation into the personal hygiene product. Transfer materials may be boiled and/or dried. In various embodiments, cotton may be boiled in water and/or hydrogen peroxide to overcome cotton’s natural hydrophobic qualities. Transfer materials may be air blown, rolled, hydroentangled, shredded, spun, combed, and/or carded, among other treatments, prior to incorporation into the personal hygiene product.

[0049] Transfer materials may be configured to wick fluid and/or moisture away from an exterior surface of absorbent layer 404. In various embodiments, transfer materials may facilitate the transfer of fluid and/or moisture toward the SAP. In various embodiments, random fiber alignment may facilitate fluid flow in all directions, thereby improving wicking action of absorbent layer 404 and/or lateral absorbency of absorbent layer 404. In various embodiments, transfer material fibers are oriented at random. Random orientation may increase the absorbency of the disposable product by using more of its surface area. However, transfer material fibers may be disposed in any suitable orientation.

[0050] In various embodiments, absorbent layer 404 may be formed by adding the SAP to the surface of the transfer material. In various embodiments, the SAP may be integrated into the transfer materials by hand and/or mechanical means. In various embodiments, the personal hygiene product comprises absorbent layer 404 disposed directly between top layer 408 and barrier layer 402. In various embodiments, absorbent layer 404 comprises a powdered and/or crystalline form. In various embodiments, absorbent layer 404 is sprayed, blown, dusted, or otherwise placed directly on barrier layer 402. In various embodiments, the personal hygiene product or portions thereof may be packaged in a biodegradable and/or degradable wrapper for ease of handling.

[0051] The quantity of cellulose fiber disposed in transfer layer 406 and/or of hydrogel in the absorbent layer 404 may depend on the desired characteristics of the personal hygiene product. Such characteristics may include the desired dimensions (size, shape, thickness) of the personal hygiene product, the type of fluid intended to be absorbed, the volume of fluid intended to be absorbed, the weight of the personal hygiene product, the speed and anticipated circumstances of decomposition of the personal hygiene product, and the like.

[0052] Barrier layer 402 may comprise a biodegradable and compostable bioplastic configured to prevent transfer of absorbed fluid from absorbent layer 404 to a user’s body or clothing. Barrier layer 402 may be configured to withstand flexion and torsion forces associated with human movement and physical activity without breaking or tearing. Barrier layer 402 may comprise a starch-based polymer. In various embodiments, barrier layer 402 is made from starches, cellulose, vegetable oils, and/or lactic acid-based materials. In various embodiments, barrier layer is waterproof and/or hydrophobic. In various embodiments, barrier layer comprises a wrapper to protect the personal hygiene product until it is ready for use. In various embodiments and with reference to Figures 1 and 2, barrier layer 402 comprises a trifold bioplastic sheet 302. The edges 304 of the trifold bioplastic sheet 302 may be heat sealed together, and the open edge 306 may be secured with a piece of biodegradable adhesive tape 308. Figure 2 illustrates the personal hygiene product in a folded configuration.

[0053] The personal hygiene product may comprise one or more adhesives to join various layers together and/or to facilitate adherence of the personal hygiene product to a user’s clothing. In various embodiments, the edges of the top layer 408 may be coupled to the edges of the barrier layer 402 with a construction adhesive. In various embodiments, the construction adhesive may secure any two or more of absorbent layer 404, transfer layer 406, top layer 408, or barrier layer 402. In various embodiments, the construction adhesive comprises a gelatin glue. However, the construction adhesive may comprise any biodegradable and/or degradable adhesive suitable for use in the personal hygiene product. In various embodiments, a positioning adhesive is disposed on a bottom surface of barrier layer 402. Positioning adhesive may comprise a gelatin glue; however, the positioning adhesive may comprise any biodegradable and/or degradable adhesive suitable for use in the personal hygiene product.

[0054] A personal hygiene product press can be used to press these naturally-occurring materials into a desired shape. With reference to Figure 3, a personal hygiene product press 200 may be made of wood or metal and comprises a base 202, a press top 204 and a lever 206.

The inner surfaces of the base and the press top may have a recess in the shape of a desired shape. If the biodegradable material is moistened with water before placing it in the press, or while it is in the personal hygiene product press, it can aid the compression of the biodegradable and/or degradable material into the proper shape and can help the material maintain that shape, as it dries.

[0055] Alternatively, the press may have a heated element that the seals the edge of the top layer to the edge of the bottom layer.

[0056] In another embodiment, the press includes a die-cutting blade used to trim the materials to the proper shape. The press may also include a compressible ridge made of rubber, or some other elastic material, which acts as a blade guard to protect the edge of the blade and to protect operators of the press from some inadvertent contact with the blades when the press is open.

[0057] In various embodiments, the present disclosure provides a method of creating a personal hygiene product using the hand press. In various embodiments, the product may comprise one or more of a top layer 408, a transfer layer 402, an absorbent layer 404, and a moisture-resistant barrier layer 402.

[0058] In various embodiments, absorbent layer 404 is formed by placing a hydrogel sheet, transfer material, and/or an amount of absorbent material in the press, pressing the amount of absorbent material in the press, and removing the pressed material from the press. In various embodiments, the pressed material is moistened before placing it in the press and is allowed to dry after removing it from the press. In various embodiments, dry, powdered or crystalline hydrogel is added to the absorbent material before it is pressed. In various embodiments, a pouch or sheet of hydrogel is layered under the transfer material.

[0059] In various embodiments, the top layer, absorbent layer, transfer layer, and/or barrier layer are layered in the press, and the press is used to seal the edges around the personal hygiene product. In various embodiments, the method further comprises trimming the edges of the top layer and barrier layer prior to sealing the edges of the top layer and barrier layer together.

[0060] In various embodiments, the top layer may be comprised of a biodegradable and/or degradable semi-permeable cotton sheet. In various embodiments, the top layer may be comprised of a biodegradable and/or degradable semi-permeable polylactic acid sheet. In various embodiments, the barrier layer may be comprised of biodegradable and/or degradable bioplastic. In various embodiments, the absorbent layer and/or transfer layer may be comprised of degradable materials such as cotton or wood fluff pulp. In various embodiments, the absorbent layer may comprise an SAP. In various embodiments, the absorbent layer and/or transfer layer may be comprised of biodegradable and/or degradable materials such as sawdust or other wood-derived materials, wool, flax fibers, hemp fibers, coconut fiber, bamboo fiber, j ute fiber and banana fiber, water lotus fiber, com, sugarcane, oat straw, rye, barley or polyvinyl alcohol or other suitable absorbent biologic materials. These materials may be more readily available or less expensive than coton or wood fluff pulp and/or be locally-sourced.

[0061] In various embodiments, the personal hygiene product may be mechanically sealed by the press action. In various embodiments, the edges of the personal hygiene product may be sealed with a heat-activated adhesive. In various embodiments, the edges of the personal hygiene product may be sealed with a water-activated adhesive. In various embodiments, the adhesive may be biodegradable and/or degradable.

[0062] The following examples are given to illustrate the present invention. It should be understood, however, that the invention is not to be limited to the specific conditions or details described in these examples.

Examples

[0063] Example 1 - Absorbency of Hvdrocolloid Materials: Submersion Test.

[0064] Approximately 400 mL of phosphate-buffered saline (PBS) was prepared in a 500 mL beaker. One-gram samples of kappa carrageenan, agarose and agar were prepared and placed into tea bags. The tea bags containing the samples were completely submerged in the PBS for 10 seconds and then the total mass of sample was measured using a scale. These steps were repeated 20 times (200 seconds), until the mass of the teabag stopped changing with subsequent submersions in PBS. To determine the total absorption per one gram of material, the masses of the saturated teabags and the original material were subtracted from each data point. As shown in Figure 4, the total absorption per gram of kappa carrageenan was approximately 22 mL per gram. For comparison purposes, a similar test was conducted on sodium polyacrylate. The sodium polyacrylate was ultimately more absorbent over time, however, in the initial seconds of the test, the kappa carrageenan absorbed more PBS more quickly than the sodium polyacrylate. Gel-blocking is a phenomenon that may be seen in powders which swell into gels, in which pressure from the powder particles which swell initially prevent liquid uptake from particles farther from the liquid source. Kappa carrageenan may be less prone to gel-blocking than sodium polyacrylate.

[0065] Example 2 - Absorbency of Hvdrocolloid materials: Lateral Test

[0066] Shallow glass containers having an approximate volume of 24 cm² were sterilized with ethanol. Approximately 5 mL blue food dye was added to 500 mL phosphate- buffered saline (PBS), which was selected to mimic the ions in menstrual blood. 0.4 g culinary- grade agar powder was distributed evenly over the bottom of the glass container. 2 mL PBS was initially pipetted into the center of glass container, with the pipette tip nearly touching the powder surface. After 2 minutes, 1 mL PBS was pipetted in the same fashion. In 2-minute intervals until the powder showed total saturation, an additional 0.5 mL PBS was pipetted onto the center of the powder.

[0067] Total saturation was determined as the point at which light pressure onto the powder/gel surface resulted in noticeable liquid desorption. If, after a certain interval of time, additional absorption occurred and the powder was no longer saturated, PBS was added in 0.5 mL increments. The above procedure was repeated with culinary -grade kappa carrageenan powder and with pressed agar flakes. As show in Figure 5, lateral absorption per gram for kappa carrageenan, within the 10-20 mL/g range, may be superior to agar powder and flakes. Gel-blocking is a phenomenon that may be seen in powders which swell into gels, in which pressure from the powder particles which swell initially prevent liquid uptake from particles farther from the liquid source. Over the small area and at the shallow powder depth in the lateral testing, gel-blocking did not appear to be an impediment to total absorption by kappa carrageenan.

[0068] Example 3 - Test of Hvdrocolloid Combinations

[0069] Approximately 400 mL of phosphate-buffered saline (PBS) will be prepared in a 500 mL beaker. One-gram combinations of kappa carrageenan (KC) and locust bean gum (LBG) will be prepared and placed into tea bags, as follows: 100% KC; 75% KC and 25% LBG; 50% KC-50% LBG; 25% KC-75% LBG; and 100% LBG The tea bags containing the samples will be completely submerged in the PBS for 10 seconds and then the total mass of sample will be measured using a scale. These steps will be repeated 20 times (200 seconds), until the mass of the teabag stops changing with subsequent submersions in PBS. To determine the total absorption per one gram of material, the masses of the saturated teabags and the original material will be subtracted from each data point. Kappa carrageenan in combination with one or more other biologic hydrocolloids may provide improved absorbency.

[0070] Example 4 - Test of Hydrocolloid Materials with Ionic Salts

[0071] Approximately 400 mL of phosphate-buffered saline (PBS) was prepared in a

500 mL beaker. One-gram samples of agarose, alginate, and Gran-Sorb (a cellulose-based industrial absorbent) were prepared and placed into tea bags. A one-gram sample of alginate with calcium chloride was also prepared. The tea bags containing the samples were completely submerged in the PBS for 10 seconds and then the total mass of sample was measured using a scale. These steps were repeated 20 times (200 seconds), until the mass of the teabag stopped changing with subsequent submersions in PBS. To determine the total absorption per one gram of material, the masses of the saturated teabags and the original material were subtracted from each data point. As shown in Figure 6, the absorbance of agarose was approximately 10.5x its original mass, while Gran-Sorb showed absorbency at only twice its mass. The absorbency of alginate was decreased with the addition of calcium chloride.

[0072] Example 5 - Test of Hydrocolloid Materials with Ionic Salts

[0073] Approximately 400 mL of phosphate-buffered saline (PBS) will be prepared in a 500 mL beaker. One-gram samples of kappa carrageenan (KC), Locust Bean Gum (LBG) and Xanthan Gum (XG) will be prepared and placed into tea bags. KC, LBG and XG will also be individually combined with 10% weight sodium chloride in order to form one-gram samples, and be placed into tea bags. The tea bags containing the samples will be completely submerged in the PBS for 10 seconds and then the total mass of sample will be measured using a scale. These steps will be repeated 20 times (200 seconds), until the mass of the teabag stops changing with subsequent submersions in PBS. To determine the total absorption per one gram of material, the masses of the saturated teabags and the original material will be subtracted from each data point. Kappa carrageenan in combination with one or more other ionic salts may provide improved absorbency.

[0074] Example 6 - Construction of Hydrogel Sheets

[0075] Hydrogel molds were created in SolidWorks and 3D-printed. Each mold had the same area dimensions, but 3 were printed with varying waffle-print patterns. Each mold was closely lined with a sheet of aluminum foil. Each was labeled, and the masses of the foil sheets and molds were recorded. A 50 mL beaker and a stir bar were sterilized with ethanol and placed on a hot plate. For several distinct batches of kappa carrageenan, different parameters were altered to measure their effects on the properties of the hydrogel as they dehydrated into sheets. Variables included cotton fiber quantity and alignment used in the hydrogel sheet; amounts of kappa carrageenan powder; solvents (H20 PBS and hydrogen peroxide; H20/PBS + small concentration of hydrogen peroxide; deionized water); and presence and area fraction of holes in waffle print pattern. These variables are represented in Table 1.

[0076] Table 1

H2f>-Waier. KOKappa C&nrageenaa, FBS^phosph&is-btffared saline

[0077] The kappa carrageenan was dispersed in cold solvent using a stir bar. The temperature of the hot plate was raised to level 5 and the solution was allowed to heat and simmer for 4 minutes. The mixture was poured into a mold. The mass and dimensions of the gel were measured immediately, and regularly over the next several days. Specimens were allowed to dehydrate completely within the mold before removing it, enabling even dehydration over the surface of the gel. The specimen prepared with 0.2g of kappa carrageenan and 15 mL water produced a thin, flexible hydrogel sheet approximately 50-100 um in depth that was sufficiently strong and durable for use in a feminine hygiene product without breaking.

[0078] Example 7 - Absorbency of Treated Cotton

[0079] Organic cotton was boiled at three different time intervals (five, ten and 15 minutes) in water. The samples were left to air dry for 36 hours before absorption tests. A one- gram unit of each sample, and a one-gram unit of the absorbent material contained in a non- biodegradable, commercially-available feminine hygiene pad, were placed in tea bags. The tea bags were then submerged in a beaker containing deionized water. Each tea bag was completely submerged for 20 seconds and then the total mass of the sample was measured using a scale. The absorbed fluid per one gram of material was calculated by subtracting out the weight of the tea bag and the mass of the material. These steps were repeated until the mass of the sample changed less than 0.01 grams between submersion intervals. As shown in Figure 7, the 15 minute boiled cotton had the largest average absorbance values during each time interval, at 18.0 grams. The cotton that was boiled for 15 minutes absorbed more water on average than the absorbent material contained in the commercially-available feminine hygiene pad, which held an average of 17.0 grams. The 10 minute boiled cotton held 13.7 grams and 5 minute boiled cotton held 16.6 grams.

[0080] It will be apparent to those skilled in the art that various modifications and variations can be made in the present disclosure without departing from the spirit or scope of the disclosure. Thus, it is intended that the embodiments described herein cover the modifications and variations of this disclosure provided they come within the scope of the appended claims and their equivalents.

[0081] Numerous characteristics and advantages have been set forth in the preceding description, including various alternatives together with details of the structure and function of the devices and/or methods. The disclosure is intended as illustrative only and as such is not intended to be exhaustive. It will be evident to those skilled in the art that various modifications can be made, especially in matters of structure, materials, elements, components, shape, size and arrangement of parts including combinations within the principles of the invention, to the full extent indicated by the broad, general meaning of the terms in which the appended claims are expressed. To the extent that these various modifications do not depart from the spirit and scope of the appended claims, they are intended to be encompassed therein.

Claims

CLAIMS What is claimed is:

1. A personal hygiene product comprising:

a top layer;

a transfer layer;

an absorbent layer; and

a barrier layer;

wherein at least one of the top layer, the transfer layer, the absorbent layer, and the barrier layer comprise a biodegradable material.

2. The personal hygiene product as in claim 1, wherein the biodegradable material comprises at least one of banana leaves, rice, cotton, wood fibers, agarose, agar, carrageenan, polyvinyl alcohol, sodium silicate, polyhydroxybutyrate, and polyhydroxyalkanoate.

3. The personal hygiene product as in claim 2, wherein the personal hygiene product is fully biodegradable.

4. The personal hygiene product as in claim 1, wherein the absorbent layer comprises a hydrogel.

5. The personal hygiene product as in claim 4, wherein a particulate is dispersed in the hydrogel.

6. The personal hygiene product as in claim 5, wherein the particulate comprises at least one of cotton or wood.

7. The personal hygiene product as in claim 6, wherein the cotton comprises boiled cotton.

8. A hydrogel for use in a personal hygiene product, comprising:

at least one of rice, agarose, agar, carrageenan, polyvinyl alcohol, sodium silicate, polyhydroxybutyrate, and polyhydroxyalkanoate.

9. The hydrogel as in claim 8, further comprising an ionic salt.

10. The hydrogel as in claim 9, wherein the ionic salt comprises at least one of calcium chloride, calcium hydroxide, potassium chloride, potassium hydroxide, sodium chloride and sodium hydroxide, magnesium chloride and magnesium hydroxide.

11. The hydrogel of claim 8, further comprising an integrated transfer material, wherein the transfer materials comprises at least one of cotton, wood fluff pulp, sawdust, wool, flax fiber, hemp fiber, coconut fiber, bamboo fiber, jute fiber, banana fiber, water lotus fiber, com, sugarcane, oat straw, rye, barley or polyvinyl alcohol.

12. The hydrogel as in claim 11, wherein fibers of the transfer material are randomly oriented.

13. The hydrogel as in claim 8, comprising a depth of between 10 um and 1000 um.

14. The hydrogel as in claim 8, comprising 0.5% to 25% kappa carrageenan by weight and 75% to 99.5% wood fluff pulp by weight.

15. The hydrogel as in claim 8, comprising 0.5% to 25% kappa carrageenan by weight and 75% to 99.5% cotton by weight.

16. The hydrogel as in claim 8, comprising between 0.1% and 70% kappa carrageenan by weight.

17. A personal hygiene product comprising:

a top layer coupled to an absorbent layer by an adhesive, and

a barrier layer coupled to the absorbent layer by the adhesive, wherein

the personal hygiene product is fully degradable.

18. The personal hygiene product of claim 17, wherein the absorbent layer comprises a superabsorbent polymer integrated with a transfer material,

wherein the superabsorbent polymer comprises at least one of rice, agarose, agar, carrageenan, polyvinyl alcohol, sodium silicate, polyhydroxybutyrate, and

polyhydroxyalkanoate, and

wherein the transfer materials comprises at least one of cotton, wood fluff pulp, sawdust, wool, flax fiber, hemp fiber, coconut fiber, bamboo fiber, jute fiber, banana fiber, water lotus fiber, com, sugarcane, oat straw, rye, barley, or polyvinyl alcohol.

19. The personal hygiene product of claim 18, wherein the top layer comprises a porous or semi-permeable woven or nonwoven sheet comprising at least one of cotton, polylactic acid, or cellulose-based material.

20. The personal hygiene product of claim 19, wherein the barrier layer comprises a biodegradable bioplastic comprising at least one of cellulose, starch, vegetable oil, or lactic acid-based material.