DESC:FIELD OF THE INVENTION
The present invention relates to a sanitary pad, and more specifically to a flushable and biodegradable sanitary pad or panty liner suitable for use in any climatic condition. The invention addresses the challenges associated with menstrual hygiene, particularly the environmental burden of plastic-based products and the social stigma linked to disposal in culturally sensitive or resource-limited settings. Constructed using hypoallergenic, chemical free, plant based materials such as hemp fibers, viscose fibers, cellulose, pulverized hemp, polyvinyl alcohol (PVA), airlaid nonwoven sheets, bio-based superabsorbent polymers (SAPs), and an organic, non-toxic, plant-based adhesive glue gum, the pad ensures high absorbency, comfort, biodegradability, and skin safety. The use of nonwoven structures with short fibers (=3 mm) enhances flushability, making the product suitable for discreet and eco-friendly disposal without requiring waste bins or incineration. This invention thus offers a sustainable, comfortable, and dignified menstrual hygiene solution, particularly applicable for use in rural areas, institutional settings, emergency relief, and by environmentally conscious consumers seeking alternatives to traditional plastic-based products.
BACKGROUND OF THE INVENTION
Menstrual hygiene refers to the practices and products used to manage menstruation in a safe, hygienic, and dignified manner. It includes access to clean absorbent materials, soap and water for personal hygiene, private spaces for changing, and safe disposal options. Maintaining menstrual hygiene is essential not only for physical health but also for mental and social wellbeing. It enables women and girls to continue their daily activities, such as attending school or going to work, without interruption or stigma.
Lack of proper menstrual hygiene can lead to a range of health issues. Common consequences include reproductive tract infections (RTIs), urinary tract infections (UTIs), skin irritations, and allergic reactions. Poor hygiene during menstruation has also been linked to long term health complications, including cervical cancer. Additionally, inadequate menstrual care can cause psychological distress, reduced self-esteem, and social withdrawal.
Social and cultural stigmas around menstruation persist in many parts of the world, including India. In rural and semi-urban communities, menstruation is often shrouded in secrecy, with restrictions placed on menstruating individuals in temples, kitchens, and schools. Girls frequently report being unaware of menstruation before menarche, and due to shame or lack of facilities, many drop out of school after reaching puberty. These issues are compounded by economic barriers, where millions cannot afford proper sanitary products, resorting instead to unhygienic alternatives like old cloth, ashes, husk, or newspaper.
Globally, the problem of period poverty the inability to afford or access menstrual hygiene products remains widespread. In developing countries, many women face similar challenges, including lack of sanitation infrastructure and education. Even in high income countries, marginalized populations encounter difficulties in maintaining menstrual hygiene due to affordability or social stigma.
To address these concerns, various menstrual products have been introduced, such as disposable sanitary pads, tampons, menstrual cups, cloth pads, and period underwear. Governments and nongovernmental organizations (NGOs) have also launched awareness and distribution campaigns. However, the widespread use of disposable sanitary pads has led to another significant problem of environmental pollution.
Menstrual hygiene management, a crucial aspect of feminine health, is witnessing a significant shift in global trends. With the feminine hygiene products market projected to reach USD 51.13 billion by 2027, the sector is ripe for innovation. A dominant share of this market belongs to sanitary pads. However, traditional sanitary pads, typically made of plastic and superabsorbent polymers, pose significant environmental challenges due to their non-biodegradable nature. These products often end up in landfills or water bodies, contributing to pollution and environmental degradation. Moreover, in countries with a high population density, such as India, the disposal of these products is a pressing issue, given the logistical and cultural challenges associated with menstruation.
In addition to their environmental impact, conventional sanitary products often contain synthetic materials and chemical additives that can cause skin irritation or allergic reactions. Many users are now seeking alternatives that are safer, natural, and biodegradable. Consequently, there is a growing demand for menstrual products made from sustainable materials such as organic cotton, bamboo fiber, hemp, and plant based films. These innovations aim to reduce ecological damage while ensuring user comfort and safety.
Despite these efforts, challenges remain in terms of scalability, cost-effectiveness, and user education. Many biodegradable products are still relatively expensive and not widely available in rural or low-income settings. Disposal infrastructure, especially for compostable or water soluble products, is lacking in many regions. Therefore, the need for a practical, affordable, and environmentally friendly menstrual hygiene solution is more urgent than ever.
Several patent documents have addressed aspects of biodegradable sanitary products. US7858157B2 discloses absorbent articles using hydrophilic nonwoven fabrics for improved fluid handling, but it relies on synthetic, non-biodegradable fibers. WO2019093700A1 introduces natural absorbers like seaweed but lacks a structured multi-layer absorbent core with optimized fluid retention. CN202801943U provides a biodegradable sanitary napkin made from lactic acid polymer nonwovens but does not disclose plant-based adhesives or water-soluble wings. Similarly, CN202477990U describes a fully biodegradable napkin but does not discloses an advanced odor control features. WO2019167054A1 attempts to offer low-cost pads using agricultural by-products like bagasse; however, it falls short in absorption performance, structural integrity and user comfort.
Several non-patent literature sources highlight the importance and ongoing efforts in menstrual hygiene management, yet each presents limitations when compared to the present invention. The UNICEF guidance document outlines policy and educational frameworks for menstrual health but does not suggest product-level innovations or material solutions (Guidance on menstrual health and hygiene, Programme Division/WASH 3 United Nations Plaza New York, NY 10017 USA, 1st edition, March 2019). Jeyakanthan et al. examine ecological absorbent cores using kenaf and chitosan fibers, validating the potential of natural materials but falling short of presenting a complete, multi-layered product design with integrated adhesives or wings (Materials Science and Applications, 14, 363-381, 2023). Dinu et al. (2022) focus on the biodegradation of natural fibers versus synthetic hygiene products, but their work emphasizes post-use decay rather than functional performance such as fluid retention or comfort (Fermentation 2022, 8, 287). Garg et al. explore government-subsidized menstrual health programs in India, identifying systemic challenges but without addressing product innovation or material development (Maternal and Child Health Journal, April 2011, 16(4):767-74). Barari and Thakur (2023) advocate for reusable biodegradable pads but do not consider the practicality and user-preference for disposable products, especially in resource-limited or culturally sensitive environments (International Journal of Innovative Science and Research Technology, August 2023, 8(8):995-1002).
In contrast to conventional plastic-based sanitary products, the present invention offers a fully biodegradable, single use sanitary pad featuring a multi-layered structure composed of pulverized hemp, bio-based superabsorbent polymers (bio-SAPs), an airlaid absorbent matrix, and water soluble adhesives. This innovative design addresses critical challenges in menstrual hygiene by combining natural materials with high absorbency, comfort, and eco-friendly disposal. The concept of a flushable sanitary pad further enhances usability by eliminating the need for separate disposal mechanisms, making it particularly impactful in regions like rural and semi-urban India, where cultural stigma and waste infrastructure limitations hinder safe menstrual hygiene practices. As global consumers become increasingly conscious of environmental sustainability, such products represent a timely solution aligned with both ecological responsibility and user dignity, offering a transformative opportunity in the growing market for sustainable menstrual hygiene solutions.
OBJECT OF THE INVENTION
The principal object of the present invention is to provide a flushable nonwoven sanitary pad and panty liner that is biodegradable, eco-friendly, and suitable for use in all climatic conditions, including both hot and cold environments.
Another object of the invention is to ensure that the flushability and biodegradability of the sanitary pad are achieved without compromising on key functional attributes, such as absorbency, comfort, safety, and affordability.
A further object of the present invention is to enable the pad’s disintegration in water across a range of temperatures, making it suitable for year-round disposal depending on seasonal water availability.
Another object of the present invention is to provide a cost-effective alternative to conventional plastic-based sanitary pads by offering a product that is hypoallergenic, free from harmful chemicals, and designed to ensure comfort and skin safety for users.
Additionally, the invention seeks to address cultural and infrastructural barriers to menstrual hygiene by offering a solution that allows discreet, hygienic, and dignified disposal, especially in regions where traditional disposal methods are restricted or stigmatized.
Another object of the present invention is to investigate and validate the pad’s physical, mechanical, and fluid absorption properties, as well as its dispersion in water and biodegradability under real-world conditions, thereby confirming its performance, durability, and environmental sustainability.
In the development of sustainable and economical flushable sanitary pads, key issue need to addressed include the structure and process parameters to be optimized to maximize the pad's absorbency, comfort, and flushability without compromising its biodegradability. Another issue is related to standardized and industry-accepted testing methods to be employed to accurately assess the pad's performance metrics such as fluid absorption, dispersion in water, and biodegradability. It is challenging to provide affordable pad capable of maintaining high quality and environmental standards, especially for target markets like rural India. Non availability of comprehensive procedures and labelling guidelines for flushable sanitary pads that ensures transparency and adherence to flush ability standards. Strategies to be employed for effectively overcoming cultural stigmas and consumer habits associated with traditional sanitary pad disposal, encouraging adoption of this pad needs to be defined.
Availability of such pads holds profound social implications, especially for women in societies where menstrual disposal is a sensitive issue. The discreet and hygienic disposal method afforded by these flushable pads preserve women's dignity and privacy, helping to destigmatize menstruation and improve overall menstrual hygiene practices. The production of flushable sanitary pads could spur economic growth by creating new jobs in the manufacturing sector. It also opens the market to an innovative, environmentally-friendly product that meets a pressing consumer demand, thus encouraging economic activity. By providing a hygienic disposal method, the pads can significantly reduce the risk of infection and cross-contamination associated with improper disposal of menstrual waste. This contributes to the overall health and well-being of women, and the community at large.
SUMMARY OF THE INVENTION
The present invention provides a flushable and biodegradable sanitary pad or panty liner designed for effective menstrual hygiene management with minimal environmental impact. The invention particularly addresses the need for eco-friendly, skin-safe, and convenient-to-dispose sanitary products, especially in regions lacking adequate menstrual waste infrastructure.
The sanitary pad (1) comprises a multi-layered nonwoven structure that includes a top layer (2), an acquisition and distribution layer (3), an absorbent core layer (4), a retention layer (5), and a bottom layer (6), along with lateral wings (7) and adhesive strips (8) covered with release paper (9). Each layer is carefully designed and composed of plant-based, biodegradable, and water-soluble materials to ensure complete disintegration upon flushing and compostability upon disposal.
The top layer (2) is a soft, nonwoven fabric composed of hemp fibers, viscose fibers, or a blend of both (in equal proportions), with fiber lengths of =3 mm to ensure flushability. The acquisition and distribution layer (3) is a water-soluble, dry-formed airlaid nonwoven sheet made of cellulose fibers, designed to rapidly absorb and laterally distribute fluid. The absorbent core layer (4) is also formed from a water-soluble airlaid nonwoven fabric integrated with 25–35% by weight of a bio-based superabsorbent polymer (SAP) composition comprising almond gum (50–80%), arabic gum (5–20%), and starch (5–20%) along with 5–6% pulverized hemp fibers with fiber lengths of =3 mm to enhance absorbency and odor control.
The retention layer (5) reinforces vertical fluid wicking and retention and is made of a water-soluble, cellulose-based airlaid sheet. The bottom layer (6) is a flushable and biodegradable barrier layer composed of polyvinyl alcohol (PVA), preventing leakage while dissolving effectively in water.
The wings (7) are constructed from the same material as either the top or bottom layer, are ultrasonically welded or glued using a non-toxic, plant-based adhesive. The adhesive strips (8), which secure the pad to underwear, are composed of biodegradable, pressure-sensitive plant-based adhesives, and are covered with a one-sided wax-coated release paper (9).
The sanitary pad is lightweight with an average weight of 8.26 grams and thin having an average thickness of 2.26 mm, ensuring comfort and discretion during use. It is designed to function effectively across varying climatic conditions, dissolving in both hot and cold water as per seasonal availability.
This invention overcomes several limitations of conventional plastic-based sanitary products by offering a flushable, hypoallergenic, non-toxic, cost-effective, and environmentally sustainable solution, suitable for a wide range of users, including those in rural, resource-limited, or culturally sensitive environments.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings are included to provide a clear understanding of the present invention and a detailed description, and it constitutes a part of this complete specification.
FIG. 1 is a schematic diagram showing a flushable and biodegradable nonwoven sanitary pad as per present invention.
List of designations/ reference numbers in figure
1. a flushable biodegradable sanitary pad
2. a top layer
3. an acquisition and distribution layer
4. an absorbent core layer
5. a retention layer
6. a bottom layer
7. wings
8. adhesive strips
9. a release paper
DETAILED DESCRIPTION OF THE INVENTION
Before the present invention is described in further detail, it should be understood that the invention is not limited in its application to the specific components, configurations, or methods as described herein. Various modifications and adaptations that do not depart from the scope and spirit of the invention will be evident to those skilled in the art. Multiple embodiments of the invention may be realized, and these may differ from the illustrative examples provided in the present disclosure.
Accordingly, it is to be understood that such variations and modifications are intended to be included within the scope of this invention. Descriptions of well-known elements, techniques, or methods may be omitted for clarity and brevity where appropriate. The terminology used in this specification is intended to describe particular embodiments only and is not intended to be limiting.
Features described with respect to one embodiment may be combined with or used in place of those of other embodiments. Unless context clearly indicates otherwise, the singular forms "a," "an," and "the" include plural referents. The use of the term "comprises" or "comprising" is intended to indicate non-exclusive inclusion, such that a system, method, or composition that comprises one or more stated elements may include additional elements not expressly listed.
Accordingly, the present invention relates to a flushable biodegradable sanitary pad and a method of preparing the same. More particularly, the invention pertains to a multilayered sanitary pad construction comprising biodegradable and water-dispersible materials, including a non-absorbent bottom layer, an absorbent core with high fluid retention capacity, and an acquisition and distribution layer, all configured to offer effective absorbency, comfort, hygiene, and eco-friendly disposal through conventional flushing systems.
As shown in FIG. 1, a flushable biodegradable sanitary pad (1) comprises a top layer (2), an acquisition and distribution layer (3) positioned adjacent to and in direct contact with the top layer (2), an absorbent core layer (4) positioned adjacent to and in direct contact with the acquisition and distribution layer (3), a retention layer (5) positioned adjacent to and in direct contact with the absorbent core layer (4), and a bottom layer (6) positioned adjacent to and in direct contact with the retention layer (5). Wings (7) are attached to the lateral sides of the sanitary pad (1), and adhesive strips (8) are affixed to the undersides of the bottom layer (6) and the wings (7).
After arranging the top layer (2), the acquisition and distribution layer (3), the absorbent core layer (4), the retention layer (5) and the bottom layer (6) in an order as discussed in previous paragraph, all these layers are welded from its periphery using an ultrasonic welding technique to firmly hold the various layers with respect to each other to form a pad. The wings (7) are welded to sides of the pad so formed using ultrasonic welding or glued using an organic, non-toxic, plant-based adhesive glue gum.
The top layer (2) of the flushable biodegradable sanitary pad (1) is configured to remain in direct contact with the skin of the user and serves as the initial interface for fluid intake. This layer is composed of a nonwoven fabric made from natural, plant-based fibers, selected specifically for their biodegradability, softness, and fluid permeability. In a preferred embodiment, the nonwoven fabric is composed of hemp fibers, viscose fibers, or a blend of hemp and viscose fibers in equal proportions, wherein the fiber length is equal to or less than 3 mm. This short fiber length is critical for maintaining the flushability of the product by enabling the layer to disintegrate efficiently in water without clogging or damaging plumbing systems. The top layer (2) is designed to be hypoallergenic, chemical-free, and breathable, ensuring a gentle and irritation-free experience during use. The nonwoven structure provides a soft, cloth-like texture, enhancing user comfort, while its porous configuration enables quick fluid penetration into the underlying acquisition and distribution layer (3). In one embodiment, the top layer (2) has a basis weight of approximately 20 grams per square meter (GSM) and a thickness ranging from 0.23-0.5 mm, which contributes to the overall thin profile and comfort of the sanitary pad (1) without compromising absorbency or structural integrity. The natural fibers used in the top layer (2) are derived from renewable plant sources, making it an environmentally sustainable alternative to synthetic plastic-based topsheets commonly used in conventional sanitary pads. Additionally, the nonwoven layer may be thermally bonded or hydroentangled, avoiding the use of synthetic chemical binders, further supporting its biodegradability and compostability.
The acquisition and distribution layer (3) is disposed immediately beneath the top layer (2) and is configured to perform the dual function of rapid fluid acquisition and lateral distribution of menstrual fluid across the surface area of the absorbent structure. This layer plays a critical role in preventing fluid pooling and ensuring that the underlying absorbent core layer (4) is utilized efficiently for maximum absorption. In the present invention, the acquisition and distribution layer (3) comprises a water-soluble, dry-formed airlaid nonwoven sheet made primarily from cellulose-based fibers. The dry-forming (airlaid) process ensures that the fibers are randomly oriented and bonded without the use of water, producing a porous and open structure that facilitates quick fluid intake and multi-directional wicking. The use of water-soluble and biodegradable cellulose fibers allows the layer to break down quickly upon contact with water, ontributing to the overall flushability and biodegradability of the sanitary pad (1). In a preferred embodiment, the acquisition and distribution layer (3) has a basis weight of approximately 74 GSM and a thickness of about 0.43 mm, which provides a balanced combination of structural integrity, fluid management capacity, and disintegration behavior. The layer may optionally include mild thermal bonding or biodegradable binding fibers to maintain integrity during dry use while still ensuring disintegration in water during disposal. The porous and compressible nature of the airlaid sheet ensures that menstrual fluid is rapidly drawn away from the skin through the top layer (2), thereby reducing wetness and the risk of irritation. Once absorbed, the fluid is evenly spread across the surface of the absorbent core layer (4), enhancing fluid management performance and preventing localized saturation. Due to its plant-derived composition, lack of synthetic polymers, and water-soluble characteristics, the acquisition and distribution layer (3) aligns with the overall objective of the invention to offer a fully biodegradable, skin-friendly, and environmentally responsible menstrual hygiene product.
The absorbent core layer (4) is positioned beneath the acquisition and distribution layer (3) and functions as the primary fluid retention component of the flushable biodegradable sanitary pad (1). This layer is specifically engineered to receive, rapidly absorb, evenly distribute, and securely retain menstrual fluid while maintaining the overall biodegradability and flushability of the product. In the present invention, the absorbent core layer (4) comprises a water-soluble airlaid nonwoven sheet formed primarily from cellulose-based fibers, integrated with a carefully optimized blend of bio-based superabsorbent polymers (SAPs) and pulverized hemp fibers. The combination of materials ensures superior fluid management performance, including high absorption capacity, fast wicking, and effective odor control, while supporting environmental sustainability.
In one embodiment, the absorbent core layer (4) comprising a water-soluble airlaid nonwoven sheet integrated with 25–35% by weight of a bio-based superabsorbent polymer (SAP) composition and 5–6% by weight of pulverized hemp fibers. The bio-based SAP composition used in this layer includes; 50–80% by weight of almond gum, 5–20% by weight of arabic gum, and 5–20% by weight of starch, each selected for their natural absorbency, biodegradability, and skin compatibility. Integration of pulverized hemp fibers, enhance the layer’s structural integrity and contribute to fluid retention and odor neutralization due to their inherent absorbent and antimicrobial properties. The airlaid nonwoven matrix provides an open, fibrous structure that facilitates rapid intake and uniform dispersion of fluid, minimizing saturation spots and leakage. In one embodiment, the absorbent core layer (4) has a basis weight of approximately 87 GSM and a thickness of about 0.45 mm, which balances absorbency, comfort, and disintegration characteristics. The materials used in the layer are fully biodegradable and water-dispersible, ensuring that the core disintegrates efficiently upon flushing, without clogging plumbing systems. The incorporation of plant-derived SAPs and natural fibers, as opposed to synthetic polyacrylates or petrochemical absorbents, addresses concerns associated with environmental pollution and long-term decomposition. Furthermore, the design ensures that the pad remains lightweight, flexible, and comfortable during wear, while achieving the desired fluid retention capacity for effective menstrual hygiene protection. Accordingly, the absorbent core layer (4) contributes significantly to the overall functionality, sustainability, and user safety of the sanitary pad (1), aligning with the objectives of providing a flushable, biodegradable, and high-performance menstrual hygiene product.
The retention layer (5) is disposed directly beneath the absorbent core layer (4) and is configured to reinforce fluid retention, improve vertical wicking, and provide additional containment of absorbed menstrual fluid. This layer acts as a secondary barrier that holds residual fluid within the absorbent structure, preventing rewetting and potential leakage, thereby enhancing the overall hygienic performance and user comfort of the sanitary pad (1). In the present invention, the retention layer (5) comprises a water-soluble, dry-formed cellulose-based airlaid nonwoven sheet, which maintains the product’s flushability and biodegradability while contributing to its absorbent performance. The airlaid formation process ensures a soft, porous, and lightweight structure with high capillarity and uniform fluid spreading, especially after the initial intake by the absorbent core layer (4). The layer is primarily composed of natural cellulose fibers derived from sustainable sources such as wood pulp or agricultural biomass. These fibers are selected for their hydrophilic properties, biodegradability, and water solubility, ensuring that the layer disintegrates effectively when flushed and does not contribute to environmental pollution. Optionally, small amounts of biodegradable binder fibers (e.g., polylactic acid or thermoplastic starch-based fibers) may be used to maintain structural integrity prior to disposal, without affecting the pad’s environmental profile. In a preferred embodiment, the retention layer (5) has a basis weight of approximately 74 GSM and a thickness of about 0.43 mm. These parameters are optimized to achieve a balance between fluid holding capacity, wicking speed, and dissolution behavior, ensuring the pad remains effective during use while facilitating safe and convenient disposal afterward. The role of the retention layer (5) is especially critical in minimizing the risk of leakage or backflow under pressure (e.g., when the user sits or moves), thereby improving the overall dry feel and reliability of the pad. It also acts as a transitional interface between the absorbent core layer (4) and the bottom barrier layer (6), contributing to the efficient movement and containment of fluid within the absorbent structure. By using biodegradable, water-dispersible components, the retention layer (5) supports the core objectives of providing a high-performing, user-safe, and eco-friendly menstrual hygiene product that can be flushed without risk and disposed of without guilt or environmental burden.
The bottom layer (6) of the flushable biodegradable sanitary pad (1) is positioned adjacent to and in direct contact with the retention layer (5) and serves as the barrier layer that prevents the downward leakage of menstrual fluid. This layer is specifically designed to provide fluid impermeability, while also maintaining the overall biodegradability, water solubility, and flushability of the sanitary pad (1).
In the present invention, the bottom layer (6) is composed of a biodegradable and water-soluble layer, preferably made from polyvinyl alcohol (PVA) film. PVA is a synthetic yet environmentally friendly polymer known for its excellent water solubility, non-toxicity, biodegradability, and ability to form thin, flexible, yet effective barrier layer. Upon flushing, the PVA film dissolves in water, allowing the pad to disintegrate safely in both hot and cold conditions, depending on the local climatic and plumbing environment. The PVA film used in the bottom layer (6) is formulated to retain sufficient mechanical strength and flexibility during use, yet rapidly disintegrate upon exposure to water. This allows the pad to remain intact during wear and provide reliable protection, while ensuring safe disposal via toilets without contributing to sewage system blockage. In one embodiment, the bottom layer (6) has a basis weight of approximately 36 GSM and a thickness of about 0.47 mm, offering an optimal balance between structural support, barrier function, and dissolution behavior. These physical properties are carefully chosen to align with the weight and thickness of other layers, contributing to the overall comfort, compactness, and uniformity of the sanitary pad (1). Optionally, the bottom layer (6) also provides a surface for attachment of pressure-sensitive adhesive strips (8), which are used to secure the pad to the user's underwear. The PVA film is compatible with ultrasonic welding or organic plant-based adhesives, enabling seamless integration with the adhesive system and biodegradable wings (7) without compromising eco-performance. As the final structural barrier of the pad, the bottom layer (6) plays a key role in maintaining leakage protection, structural cohesion, and disposability, reinforcing the pad’s ability to serve as a practical, hygienic, and environmentally responsible menstrual product for everyday use in a wide range of settings.
The wings (7) are flexible extensions provided on the lateral sides of the flushable biodegradable sanitary pad (1), designed to wrap around the sides of the user’s underwear for enhanced positional stability and leakage protection. The primary function of the wings (7) is to secure the pad in place during physical movement and provide an additional barrier against side leakage. In the present invention, the wings (7) are made from the same material as either the top layer (2) “a nonwoven fabric composed of hemp fibers, viscose fibers, or a blend of both” or the bottom layer (6) “a water-soluble biodegradable film such as polyvinyl alcohol (PVA)”. This material selection ensures that the wings (7) maintain compatibility with the overall biodegradable and flushable profile of the sanitary pad (1), allowing the wings to disintegrate effectively in water without contributing to environmental pollution or sewage blockages. The wings (7) are ultrasonically welded or glued to the sides of the pad using a non-toxic, plant-based adhesive glue gum, thereby eliminating the need for synthetic resins or heat-sensitive chemical binders. The welding or gluing method is selected to ensure that the wings remain securely attached during use, while enabling full biodegradability and compostability upon disposal. Each wing (7) is shaped and sized to fold neatly under the user’s underwear and align with the adhesive strips (8), which are affixed to the undersides of the wings to facilitate firm but removable attachment. The wings also serve as comfort flaps, preventing the pad from shifting or bunching during walking, running, or sitting, thereby enhancing the user's confidence and mobility. Due to their flexible and soft construction, the wings (7) conform to the contours of the undergarment without causing discomfort, while simultaneously offering added coverage and side protection, particularly during heavier menstrual flow. Since the materials used are hypoallergenic, breathable, and biodegradable, the wings contribute to both user safety and environmental sustainability. In summary, the wings (7) are an integral component of the pad design, combining comfort, security, biodegradability, and flushability, while supporting the broader objective of delivering a convenient, dignified, and eco-conscious menstrual hygiene solution.
The adhesive strips (8) are provided on the undersides of the bottom layer (6) and the wings (7) of the flushable biodegradable sanitary pad (1) and serve the primary function of securely attaching the pad to the user’s undergarment, thereby maintaining its position during physical activity. These strips are designed to offer firm yet removable adhesion, ensuring that the pad remains in place without causing damage to fabric or leaving residue. In the present invention, the adhesive strips (8) are composed of a pressure-sensitive adhesive (PSA) formulated from a natural, non-toxic, plant-based composition. Preferably, the adhesive is derived from components such as modified starch, dextrin, gum rosin, or guar gum, which provide strong tack, flexibility, and biodegradability. Unlike conventional petroleum-based adhesives, which are non-degradable and potentially irritating to skin, the plant-based adhesive used herein is hypoallergenic, skin-safe, and eco-friendly, aligning with the overall sustainability goals of the product. The adhesive strips (8) are applied in predetermined widths and lengths to the underside of the pad, including the central portion of the bottom layer (6) and the underside of each wing (7), enabling multi-point attachment for maximum stability. These strips may be ultrasonically welded or glued using the same organic adhesive to ensure they remain affixed to the base materials without synthetic bonding agents. The adhesive strips (8) are protected prior to use by a release paper (9), which is preferably a one-sided wax-coated paper. This waxed release liner allows for easy removal of the adhesive backing without tearing or degrading the strip, while maintaining product hygiene and storage stability. Importantly, the adhesive is formulated to dissolve or degrade in water, enabling the entire pad including the adhesive system to be safely flushed down the toilet under appropriate conditions, without leaving non-degradable residues in the water stream. This property is essential for ensuring the flushability of the product, particularly in regions where sanitary waste disposal infrastructure is limited or absent. In summary, the adhesive strips (8) of the present invention are designed to deliver reliable attachment, user safety, and environmental compatibility, serving as a critical interface between the sanitary pad (1) and the user’s undergarment, while supporting the invention’s core objectives of biodegradability, flushability, and comfort.
Following Table 1 shows the source from where various materials are purchased.
Table 1
Sr. No. Description of material Source
1. a nonwoven fabric composed of hemp fibers, viscose fibers or a blend of both hemp and viscose fibers in equal proportions Fabricated at the Northern India Textile Research Association (NITRA), an accredited laboratory under the Ministry of Textiles, Government of India.
Fibers are purchased from Hemp Affair Private Limited, First Floor, D-98, Sector-63, Noida - 201307, Gautam Buddha Nagar, Uttar Pradesh, India.
2 airlaid nonwoven sheet Kasa Ventures Private Limited, A-324 Chattatpur Enclave, Phase - II, South Delhi-110074
3 bio-based superabsorbent polymers (SAPs) Celligo Natural Fibers, Plot No. 71, Sriram Nagar, Sengundram, Singaperumalkoil, Oragadam Industrial Area, Chengalpattu, Tamil Nadu – 603204, India
4 polyvinyl alcohol (PVA) sheet of 40 micron Gupta Zari, L-1266, Mangol Puri, New Delhi, Delhi-110083
5 plant-based adhesive glue gum Cero Care Products LLP, A 205, TTC MIDC, Thane Belapur Road,
Navi Mumbai 400710. Maharashtra India

Best method of performing the invention
The following exemplary embodiment of the present invention is provided by way of illustration and should not be constructed to be limiting the scope of the present invention.
Table 2 shows specification of the flushable biodegradable sanitary pad (1) fabricated as per present invention.
Table 2
Sr. No. Description Specification
1. material of the top layer (2) a nonwoven fabric formed from a blend of both hemp fibers, viscose fibers in equal proportions
2 the top layer (2) weight 20 GSM
3 the top layer (2) thickness 0.5 mm
4 material of the acquisition and distribution layer (3) a water-soluble, dry-formed, cellulose fiber-based airlaid nonwoven sheet
5 The acquisition and distribution layer (3) weight 74 GSM
6 the acquisition and distribution layer (3) thickness 0.43 mm
7 material of the absorbent core layer (4) a water-soluble airlaid nonwoven sheet integrated with 30% by weight of a bio-based superabsorbent polymer (SAP) composition and 6% by weight of pulverized hemp fibers,
8 the absorbent core layer (4) weight 87 GSM
9 the absorbent core layer (4) thickness 0.45 mm
10 the bio-based SAP composition 50–80% by weight of almond gum, 5–20% by weight of arabic gum, and 5–20% by weight of starch
11 material of the retention layer (5) a water-soluble, dry-formed, cellulose fiber-based airlaid nonwoven sheet
12 the retention layer (5) weight 74 GSM
13 the retention layer (5) thickness 0.43 mm
14 material of the bottom layer (6) a biodegradable and water-soluble polyvinyl alcohol (PVA) sheet
15 the bottom layer (6) weight 36 GSM
16 the bottom layer (6) thickness 0.47 mm
17 material of the wings (7) a biodegradable and water-soluble polyvinyl alcohol (PVA) sheet
18 the wing (7) weight 36 GSM
19 the wing (7) thickness 0.47 mm
20 method of joining All the layers are welded by ultrasonic welding and wings are welded with lateral sides of the pad by ultrasonic welding
(all fibers are of length less than or equal to 3 mm)
The flushable biodegradable sanitary pad (Sample Code: 53) fabricated with specification as per above Table 2 was subjected to a comprehensive evaluation by the Northern India Textile Research Association (NITRA), an accredited laboratory under the Ministry of Textiles, Government of India. Each test was conducted to validate the safety, performance, and standard compliance of the pad. The interpretations below are provided with appropriate reference to applicable test methods and standards.
Microbial Cleanliness (Bioburden) (ISO 11737-1:2018)
The microbial cleanliness test assessed the hygienic quality of the pad by determining the total viable count of aerobic bacteria and fungi. The test results indicated a total bacterial count of less than 10 CFU/g and no detectable fungal growth, which signifies that the pad meets stringent hygiene criteria. Although the specific standard is not listed, such bioburden evaluations typically follow ISO 11737-1:2018, widely used for products in contact with skin or mucosa. The low microbial load confirms that the manufacturing and packaging processes maintain high sanitary conditions, making the product safe for intimate use.
Quality of Absorbent Filler (IS 667:1981 (RA 2022))
The absorbent filler material was tested according to IS 667:1981 (Reaffirmed 2022), which prescribes quality benchmarks for cotton and similar absorbent materials used in hygiene products. The test confirmed that the filler was 100% compliant, with no lumps, oil spots, dirt, or foreign matter. This ensures not only effective absorption but also safety and consistency in product performance. Use of such pure material contributes to the pad’s functional and environmental attributes.
Absorbency of Bottom Layer
The bottom layer, made from 100% PVA (Polyvinyl Alcohol), was tested for absorbency and reported to have no absorbent properties, which is consistent with its intended function. The bottom layer acts as a barrier that prevents backflow and leakage, while also contributing to the flushable nature of the pad due to PVA’s solubility in water. The lack of absorbency here is a positive design feature, confirming that fluid is retained within the absorbent core without escaping through the base.
Overall Pad Absorbency (IS 5405:2019, Clause 7.2)
The pad was evaluated for fluid containment performance in accordance with Clause 7.2 of IS 5405:2019, which specifies absorbency as a critical property for sanitary napkins. The result showed no leakage at the bottom or sides during fluid exposure. This indicates that the acquisition and distribution layer (ADL) and absorbent core effectively capture and hold the fluid, and the multi-layer structure works cohesively to prevent any lateral or downward escape. This is essential for user comfort and product efficacy during use.
Thickness Measurement
The pad’s thickness was determined by stacking two complete sanitary pads and measuring the combined height to compute the average. The test revealed a thickness of 2.26 mm, indicating a slim and comfortable design that supports discreet usage. This dimension reflects an optimal balance between effective fluid retention and minimal bulk, enhancing user comfort during daily wear.
Weight Determination
The weight of the sanitary pad was measured using a precise analytical balance and found to be 8.26 grams on average. This weight suggests that the materials have been carefully optimized to ensure both functionality and disposability. A lower overall mass is favorable for flushability, as lighter pads are less likely to obstruct plumbing systems, and the use of biodegradable components supports eco-conscious disposal.
Back Strip (Adhesive Layer)
The test report noted the presence of a back strip, which is a structural and usability feature. The adhesive layer ensures that the pad remains securely attached to the undergarment during use, enhancing user confidence and stability which is essential for product acceptance in the market.
This results not only ensures alignment with applicable Indian Standards but also reinforces the sanitary pad’s compliance, performance, hygiene, and user-centered design. ,CLAIMS:We Claim:
1. A flushable biodegradable sanitary pad (1), comprising:
• a top layer (2) configured to remain in contact with the skin of a user, said top layer (2) comprising a nonwoven fabric formed from hemp fibers, viscose fibers, or a blend of both in equal proportions, wherein the fibers are of length equal to or less than 3 mm to ensure flushability and having a weight of 20 GSM and a thickness in the range of 0.23 mm to 0.5 mm;
• an acquisition and distribution layer (3) disposed adjacent to and in direct contact with the top layer (2), configured to rapidly absorb and uniformly distribute menstrual fluid across the pad, said layer comprising a water-soluble, dry-formed, cellulose fiber-based airlaid nonwoven sheet having a weight of 74 GSM and a thickness of 0.43 mm;
• an absorbent core layer (4) disposed adjacent to and in direct contact with the acquisition and distribution layer (3), configured to receive, absorb, distribute, and retain menstrual fluid while providing odor control and maintaining biodegradability, the said core layer (4) comprising a water-soluble airlaid nonwoven sheet integrated with 25–35% by weight of a bio-based superabsorbent polymer (SAP) composition and 5–6% by weight of pulverized hemp fibers having fiber length less than or equal to 3 mm, wherein the bio-based SAP composition consists of 50–80% by weight of almond gum, 5–20% by weight of arabic gum, and 5–20% by weight of starch, and wherein said core layer has a weight of 87 GSM and a thickness of 0.45 mm;
• a retention layer (5) disposed adjacent to and in direct contact with the absorbent core layer (4), configured to improve fluid retention and wicking, said retention layer comprising a water-soluble, dry-formed, cellulose fiber-based airlaid nonwoven sheet having a weight of 74 GSM and a thickness of 0.43 mm;
• a bottom layer (6) disposed adjacent to and in direct contact with the retention layer (5), configured to prevent leakage of fluid, said bottom layer comprising a biodegradable and water-soluble polyvinyl alcohol (PVA) sheet having a weight of 36 GSM and a thickness of 0.47 mm;
• wings (7) attached to the lateral sides of the sanitary pad (1), wherein said wings are made from the same material as the top layer (2) or the bottom layer (6), and are joined to the pad via ultrasonic welding or by application of an organic, non-toxic, plant-based adhesive glue gum; and
• adhesive strips (8) affixed to the undersides of the bottom layer (6) and the wings (7), said strips being secured by ultrasonic welding or by the organic, non-toxic, plant-based adhesive glue gum, and covered by a release paper (9), wherein said release paper comprises a one-sided wax paper, and wherein said adhesive strips (8) are configured to securely attach the pad to the user’s underwear upon removal of the release paper (9), thereby maintaining the pad’s position during physical movement.
2. The flushable biodegradable sanitary pad (1) as claimed in claim 1, wherein the average thickness of the pad is 2.26 mm.
3. The flushable biodegradable sanitary pad (1) as claimed in claim 1, wherein the average weight of the pad is 8.26 grams.
4. The flushable biodegradable sanitary pad (1) as claimed in claim 1, wherein the pad is configured for use as a panty liner.
5. The flushable biodegradable sanitary pad (1) as claimed in claim 1, wherein after arranging the top layer (2), the acquisition and distribution layer (3), the absorbent core layer (4), the retention layer (5) and the bottom layer (6) in an order, all these layers are welded from its periphery using an ultrasonic welding technique to firmly hold the various layers with respect to each other to form a pad and the wings (7) are affixed to sides of the pad so formed using ultrasonic welding or glued using an organic, non-toxic, plant-based adhesive glue gum.