Method of making flushable degradable sanitary napkins

Abstract

The present application relates to sanitary napkin technical field, propose a kind of directly flush into toilet and carry out dispersible and degradable sanitary napkin manufacturing method of dispersible and degradable sanitary napkin body includes the surface layer, absorbent layer, liquid barrier layer, bottom layer of laminated arrangement, specific manufacturing steps are as follows: flat laying bottom layer, spiral, discontinuous glue spraying is carried out on bottom layer upper surface;The liquid barrier layer is the film layer made of soluble material, when film layer production, film layer is heat-pressed, form the concave-convex convex point grain, subsequently laid on bottom layer;The absorbent layer is laid on liquid barrier layer, subsequently spiral, discontinuous glue spraying is carried out on absorbent layer upper surface, and glue spraying is degradable environment-friendly hot melt adhesive;The surface layer is dispersible fabric layer, the dispersible fabric layer is treated with hydrophilic oil agent to achieve the effect of blood penetration, and the surface layer is laid on absorbent layer;The surface layer, absorbent layer, liquid barrier layer, bottom layer laminated and adhered together are peripherally sealed and cut into single piece sanitary napkin material.

Description

Technical Field

[0001] This invention relates to the field of sanitary napkin technology, and in particular to a method for manufacturing a flushable and biodegradable sanitary napkin. Background Technology

[0002] The international community is increasingly concerned about the environmental pollution caused by plastics, and the concept of "plastic restriction" is gradually gaining global consensus. Sanitary napkins, as a necessity for women and a disposable consumer good, are consumed in huge quantities annually. Switching to production using biodegradable materials is of paramount importance.

[0003] Biodegradable and flushable sanitary napkins refer to sanitary napkins manufactured using biodegradable and flushable materials and possessing biodegradable and flushable properties. "Biodegradable" materials are those that, under natural environmental conditions such as soil, microorganisms, and light, can completely decompose into natural small molecule compounds such as carbon dioxide and water. "Biodegradable" materials mainly include processed products from natural raw materials (such as pure cotton spunlace nonwoven fabric, pure cotton textiles, silk fabrics, etc.) and bio-based biodegradable plastics. Pure cotton textiles, silk fabrics, and other naturally occurring biodegradable materials are expensive, have poor processability, poor stability, and impure colors, making them unsuitable for the production of current sanitary products. Bio-based biodegradable plastics are derived from biomass resources (such as plant fibers, starch, etc.), are completely degradable, and have better processability and cost than the former. "Flushable" materials refer to materials that possess sufficient wet strength to withstand human waste over a long period and can disintegrate and disperse in the presence of ordinary tap water. Therefore, they can be flushed down a traditional toilet without clogging or blocking it, and can be discharged into municipal or private sewage systems for further disposal.

[0004] The "biodegradable" property is determined by the material's properties, while "fluffable" is determined by the material's processing and manufacturing process. Currently, sanitary napkins claiming to be "biodegradable" lack "fluffable" properties and cannot be naturally decomposed by flushing into the sewer system. They are ultimately incinerated through municipal waste recycling systems, thus negating the environmental benefits of "biodegradability." Therefore, this invention combines the dual concepts of "biodegradable" and "fluffable" to develop a method for manufacturing flushable and biodegradable sanitary napkins. Summary of the Invention

[0005] Therefore, in view of the above problems, the present invention proposes a method for manufacturing a flushable and biodegradable sanitary napkin that can be directly flushed into the toilet for disintegration and degradation.

[0006] To solve the above-mentioned technical problems, the solution adopted by the present invention is: a method for manufacturing a flushable and biodegradable sanitary napkin, characterized in that: the sanitary napkin body comprises a top layer, an absorbent layer, a liquid-repellent layer, and a bottom layer stacked together, and the specific manufacturing steps are as follows:

[0007] A1. Substrate preparation:

[0008] The bottom layer is laid flat on the production line. The bottom layer is a washable fabric layer. Spiral and intermittent adhesive is sprayed onto the upper surface of the bottom layer. The adhesive is a biodegradable and environmentally friendly hot melt adhesive. The adhesive does not cover the entire outline of the sanitary napkin. The purpose is to reduce the application range and amount of adhesive on the upper surface of the bottom layer, reduce the stickiness of the bottom layer, and facilitate the rapid decomposition of the bottom layer and the liquid-repellent layer under the action of water, thereby improving the washability and biodegradability of the bottom layer.

[0009] A2. Preparation of the liquid-separating layer and bonding it to the bottom layer:

[0010] The liquid barrier layer is a thin film layer made of soluble material. During the production of the thin film layer, it is hot-pressed to form a textured surface with raised dots. The diameter of the raised dots is 1-2 mm and the spacing between the raised dots is 1-2 mm. It is then laid on the bottom layer. Spiral intermittent adhesive is sprayed onto the upper surface of the thin film layer to reduce the amount of adhesive sprayed, thereby reducing the viscosity and continuity of the liquid barrier layer. The adhesive is a biodegradable and environmentally friendly hot melt adhesive. The raised dots prevent the liquid from spreading on the liquid barrier layer to alleviate side leakage. It also reduces the bonding area between the liquid barrier layer and the absorbent layer, thereby improving the flushability and biodegradability of the liquid barrier layer.

[0011] A3. Preparation of the absorbent layer and bonding it to the liquid separator:

[0012] The absorbent layer consists of an upper and lower layer of toilet paper wrapped with a blend of superabsorbent polymer (SAP) and wood pulp fluff pulp. Several dense adhesive lines, formed by intermittent spraying, are applied to the sides of the upper and lower toilet paper facing the SAP. The adhesive is a biodegradable, environmentally friendly hot melt adhesive. An adhesive surface is formed between the adhesive lines, and the gaps between them accelerate the decomposition of the absorbent layer by water, enhancing its washability and biodegradability. Both the toilet paper and fluff pulp are natural biodegradable materials. The SAP accounts for 1%-10% of the mass of the intermediate absorbent layer. The toilet paper, SAP, and wood pulp fluff pulp all possess fluid absorption properties, collectively forming a strong absorbent layer.

[0013] The absorbent layer is laid on the liquid-barrier layer, and then the absorbent layer is coated with a spiral, intermittent adhesive. The adhesive is a biodegradable, environmentally friendly hot melt adhesive.

[0014] A4. Preparation of the surface layer and bonding it to the liquid-separating layer:

[0015] The surface layer is a washable fabric layer, which is treated with a hydrophilic oil agent to achieve the effect of blood permeability. The surface layer is laid on the absorbent layer.

[0016] A5. External perimeter sealing and pressing, cutting and shaping:

[0017] The layers of top layer, absorbent layer, liquid-repellent layer and bottom layer are laminated together and then cut into individual sanitary napkin materials by cutting rollers.

[0018] The outer periphery is sealed with a dense pattern of pressure points, each with a diameter of 1-2 mm and a spacing of 1-2 mm between them. This spacing increases the speed at which water enters the sanitary napkin from the side, improving the overall decomposition efficiency, flushability, and biodegradability of the sanitary napkin.

[0019] A further improvement is that the washable fabric layer described in A1 and A4 is any one of the following: washable PLA (polylactic acid) hot-air nonwoven fabric, washable PLA (polylactic acid) direct-laid spunlace nonwoven fabric, washable PLA (polylactic acid) direct-laid spunlace nonwoven fabric, washable bamboo fiber direct-laid spunlace nonwoven fabric, and washable PHA (polyhydroxyalkanoates) direct-laid spunlace nonwoven fabric.

[0020] Further improvements were made to enhance the washability of PLA (polylactic acid) hot-air nonwoven fabric by adjusting the following parameters:

[0021] Weight 20g / ㎡-30g / ㎡, thickness 2.5mm-5mm, transverse breaking force ≥2.0N / 2 inches, transverse breaking elongation 70%-120%.

[0022] Further improvements are made to enhance the washability of PLA (polylactic acid) direct-laid spunlace nonwoven fabric, LA (polylactic acid) direct-laid spunlace nonwoven fabric, bamboo fiber direct-laid spunlace nonwoven fabric, or PHA (polyhydroxyalkanoate) direct-laid spunlace nonwoven fabric. The water pressure of the spunlace knife is adjusted during the direct-laying process to ensure that the transverse breaking force of the material reaches ≥3.0 N / 2 inch, the transverse breaking elongation is 60%-110%, and the material weight is 30 g / m²-35 g / m². Uneven thickness in some areas is permissible, but holes are not allowed.

[0023] A further improvement is that the superabsorbent polymer (SAP) mentioned in A3 is a sodium polyacrylate polymer with starch-branched chains, and the sodium polyacrylate polymer is a catalyst bio-based polymer.

[0024] A further improvement is that the toilet paper is a low-grammage toilet paper with a weight of 11g / ㎡-13g / ㎡ that does not contain wet-strength agents.

[0025] Further improvements include: the diameter of the protrusions in A2 is 1.5mm, the distance between the protrusions is 1.5mm, and the nozzle diameter is 1mm.

[0026] A further improvement is that the superabsorbent polymer (SAP) described in A3 accounts for 6% of the mass of the intermediate absorbent layer.

[0027] The further improvement is that the diameter of the pressure point described in A5 is 2mm, and the spacing between pressure points is 1.5mm.

[0028] By adopting the aforementioned technical solution, the beneficial effects of the present invention are:

[0029] 1. Currently, almost all sanitary napkins are incinerated through urban waste recycling systems. As a necessity for women, sanitary napkins are consumed in huge quantities every year. The incineration of a large number of sanitary napkins increases environmental pollution, which contradicts the environmental protection significance. Therefore, this case proposes a flushable and biodegradable sanitary napkin that can be flushed directly into the toilet and then enter the sewage system for degradation, with the aim of reducing the environmental pollution caused by sanitary napkins.

[0030] 2. The bottom layer and the liquid-repellent layer are only bonded at the edges. When the sanitary napkin is immersed in water, the water can immediately penetrate through the bottom layer and into the space between the bottom layer and the liquid-repellent layer. The uneven design of the liquid-repellent layer increases the contact area with the water, which helps to accelerate the hydrolysis of the liquid-repellent layer and improve the flushability and biodegradability of the sanitary napkin.

[0031] 3. The texture of the liquid-blocking layer is uneven, and only the raised upper surface adheres to the absorbent. On the one hand, this reduces the adhesion strength between the liquid-blocking layer and the absorbent. On the other hand, after the absorbent absorbs water and expands, the unevenness of the liquid-blocking layer will extend accordingly, providing sufficient expansion space for the absorbent, increasing the absorbency of the absorbent, accelerating the hydrolysis of the absorbent and the space for water to mix.

[0032] 4. The adhesive on the upper and lower layers of toilet paper in the absorbent layer is set as intermittent and spaced adhesive lines to form an adhesive surface, which reduces the amount of adhesive applied, resulting in a higher expansion rate between the absorbent layers and also helps the absorbent to be dispersed by water.

[0033] 5. The outer perimeter of the sanitary napkin is sealed with pressure points. The spacing between the pressure points increases the speed at which water enters the sanitary napkin from the side, improving the overall decomposition efficiency, flushability, and biodegradability of the sanitary napkin. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the bottom layer adhesive spraying structure in the method for manufacturing a washable and biodegradable sanitary napkin according to an embodiment of the present invention.

[0035] Figure 2 This is a schematic diagram of the liquid separator structure in the method for manufacturing a flushable and biodegradable sanitary napkin according to an embodiment of the present invention.

[0036] Figure 3 This is a schematic diagram of the perimeter sealing structure of a sanitary napkin in the method for manufacturing a washable and biodegradable sanitary napkin according to an embodiment of the present invention. Detailed Implementation

[0037] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments.

[0038] refer to Figures 1 to 3 The present invention discloses a method for manufacturing a flushable and biodegradable sanitary napkin. The sanitary napkin body includes a top layer, an absorbent layer, a liquid-repellent layer, and a bottom layer, which are stacked together. The specific manufacturing steps are as follows:

[0039] A1. Substrate preparation:

[0040] The bottom layer is laid flat on the production line. The bottom layer is a washable fabric layer. Spiral and intermittent adhesive is sprayed onto the upper surface of the bottom layer. The adhesive is a biodegradable and environmentally friendly hot melt adhesive. The adhesive does not cover the entire outline of the sanitary napkin. The purpose is to reduce the application area and amount of adhesive on the upper surface of the bottom layer, reduce the stickiness of the bottom layer, and facilitate the rapid decomposition of the bottom layer and the liquid-repellent layer under the action of water, thereby improving the washability and biodegradability of the bottom layer.

[0041] A2. Preparation of the liquid-separating layer and bonding it to the bottom layer:

[0042] The liquid-blocking layer is a thin film layer made of a soluble material. The material can be any one of PLA (polylactic acid), PBAT (thermoplastic biodegradable plastic), corn starch soluble film (24gsm) made of calcium carbonate, or PVA water-soluble plastic film. During film layer production, the film layer is hot-pressed to form a raised texture with bumps. The bump diameter is 1-2mm, and the bump spacing is 1-2mm. This is then laid on the bottom layer. Spiral intermittent adhesive is sprayed onto the upper surface of the film layer to reduce the amount of adhesive (0.8-1.4g / m²), reducing the viscosity and continuity of the liquid-blocking layer. The adhesive is a biodegradable, environmentally friendly hot melt adhesive. The raised texture hinders the spread of liquid on the liquid-blocking layer, thus alleviating side leakage. It also reduces the adhesion area between the liquid-blocking layer and the absorbent layer, improving the flushability and biodegradability of the liquid-blocking layer. The preferred diameter of the bumps is 1.5mm, the preferred bump spacing is 1.5mm, and the preferred adhesive nozzle diameter is 1mm.

[0043] A3. Preparation of the absorbent layer and bonding it to the liquid separator:

[0044] The absorbent layer consists of an upper layer of toilet paper and a lower layer of toilet paper wrapped with a blend of superabsorbent polymer (SAP) and wood pulp fluff pulp. The three materials are combined in a sandwich structure for easy flushing. To further improve the flushability of the sanitary napkin, the toilet paper is a low-grammage toilet paper with a weight of 11g / m²-13g / m² without wet strength agent.

[0045] The upper and lower layers of toilet paper are coated with several dense adhesive lines formed by intermittent spraying on the side facing the superabsorbent polymer (SAP). The adhesive is a biodegradable and environmentally friendly hot melt adhesive. An adhesive surface is formed between the adhesive lines, and the gaps between the adhesive lines can accelerate the decomposition of the absorbent layer by water, thereby improving the washability and biodegradability of the absorbent layer. The toilet paper and fluff pulp are both natural biodegradable materials. The superabsorbent polymer (SAP) accounts for 1%-10% of the mass percentage of the middle absorbent layer. The toilet paper, superabsorbent polymer (SAP), and wood pulp fluff pulp all have the characteristics of absorbing fluids, including blood, urine, and body fluids, which together constitute a strong absorbent layer.

[0046] The absorbent layer is laid on the liquid-barrier layer, and then the absorbent layer is coated with a spiral, intermittent adhesive. The adhesive is a biodegradable, environmentally friendly hot melt adhesive.

[0047] The preferred percentage of the superabsorbent polymer (SAP) in the intermediate absorbent layer is 6%.

[0048] A4. Preparation of the surface layer and bonding it to the liquid-separating layer:

[0049] The surface layer is a washable fabric layer, which is treated with a hydrophilic oil agent to achieve the effect of blood permeability. The surface layer is laid on the absorbent layer.

[0050] A5. External perimeter sealing and pressing, cutting and shaping:

[0051] The layers of top layer, absorbent layer, liquid-repellent layer and bottom layer are laminated together and then cut into individual sanitary napkin materials by cutting rollers.

[0052] The outer periphery is sealed with a dense pattern of pressure points, each with a diameter of 1-2 mm and a spacing of 1-2 mm. This spacing increases the speed at which water enters the sanitary napkin from the side, improving the overall decomposition efficiency, flushability, and biodegradability of the sanitary napkin. The preferred diameter of the pressure points is 2 mm, and the preferred spacing between the pressure points is 1.5 mm.

[0053] The washable fabric layer described in A1 and A4 is any one of the following: washable PLA (polylactic acid) hot-air nonwoven fabric, washable PLA (polylactic acid) direct-laid spunlace nonwoven fabric, washable PLA (polylactic acid) direct-laid spunlace nonwoven fabric, washable bamboo fiber direct-laid spunlace nonwoven fabric, and washable PHA (polyhydroxyalkanoate) direct-laid spunlace nonwoven fabric.

[0054] When PLA (polylactic acid) hot-air nonwoven fabric is selected as the washable fabric layer, in order to improve the washability of PLA (polylactic acid) hot-air nonwoven fabric, the following parameters are adjusted: weight 20g / ㎡-30g / ㎡, thickness 2.5mm-5mm, transverse breaking force ≥2.0N / 2 inches, and transverse breaking elongation 70%-120%.

[0055] When the washable fabric layer is selected as PLA (polylactic acid) direct-laid spunlace nonwoven fabric, LA (polylactic acid) direct-laid spunlace nonwoven fabric, bamboo fiber direct-laid spunlace nonwoven fabric, or PHA (polyhydroxyalkanoates) direct-laid spunlace nonwoven fabric, in order to improve the washability of PLA (polylactic acid) direct-laid spunlace nonwoven fabric, LA (polylactic acid) direct-laid spunlace nonwoven fabric, bamboo fiber direct-laid spunlace nonwoven fabric, or PHA (polyhydroxyalkanoates) direct-laid spunlace nonwoven fabric, the water pressure of the spunlace knife is adjusted in the direct-laying process. The flow rate of the water needle is 150-200m / s, and controlled at 180 for optimal performance. The adsorption negative pressure range under the net is 0.15-0.18bar, so that the transverse breaking force of the material reaches ≥3.0N / 2 inch, the transverse breaking elongation is 60%-110%, and the material weight is 30g / ㎡-35g / ㎡. Uneven thickness in some areas is allowed, but holes are not allowed.

[0056] The superabsorbent polymer (SAP) described in A3 is a sodium polyacrylate polymer with starch-embedded branches, and the sodium polyacrylate polymer is a catalyst bio-based polymer.

[0057] The environmentally friendly hot melt adhesive used in this case is existing technology, and it differs from conventional hot melt adhesives in several ways. First, it uses natural rosin resin as the adhesive, instead of petroleum resin. Second, it uses wax instead of mineral oil as the viscosity modifier. This environmentally friendly hot melt adhesive has an operating temperature as low as 120℃-130℃, a distinctive rosin scent, and its color changes from the colorless and transparent of ordinary petroleum-based hot melt adhesive to a light yellow. Its adhesion is 80% of that of ordinary petroleum-based hot melt adhesive. The hot melt adhesive is applied via a spraying process at a dosage of 1.5 g / m².

[0058] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions above are merely illustrative of the principles of the present invention. Various changes and modifications can be made to the present invention without departing from its spirit and scope. All such changes and modifications fall within the scope of the present invention as claimed, which is defined by the appended claims and their equivalents.

Claims

1. A method for manufacturing a flushable and biodegradable sanitary napkin, characterized in that: The sanitary napkin body consists of a top layer, an absorbent layer, a liquid-repellent layer, and a bottom layer, which are stacked together. The specific manufacturing steps are as follows: A1. Substrate preparation: A bottom layer is laid flat on the production line. The bottom layer is a washable fabric layer. Spiral and intermittent adhesive is sprayed onto the upper surface of the bottom layer. The adhesive is a biodegradable and environmentally friendly hot melt adhesive. A2. Preparation of the liquid-separating layer and bonding it to the bottom layer: The liquid-separating layer is a thin film layer made of soluble material. During the production of the thin film layer, the thin film layer is hot-pressed to form a textured pattern with raised dots. The diameter of the raised dots is 1.5 mm and the spacing between the raised dots is 1.5 mm. Then it is laid on the bottom layer. The upper surface of the thin film layer is sprayed with adhesive in a spiral intermittent manner. The adhesive is a biodegradable and environmentally friendly hot melt adhesive with a spray nozzle diameter of 1 mm. A3. Preparation of the absorbent layer and bonding it to the liquid separator: The absorbent layer consists of an upper layer of toilet paper and a lower layer of toilet paper wrapped around a blend of superabsorbent polymer (SAP) and wood pulp fluff pulp. Several dense adhesive lines, formed by intermittent spraying, are applied to the sides of the upper and lower layers of toilet paper facing the SAP. The adhesive is a biodegradable, environmentally friendly hot melt adhesive, and an adhesive surface is formed between the adhesive lines. Both the toilet paper and the fluff pulp are natural and biodegradable materials. The SAP accounts for 1%-10% of the mass percentage of the intermediate absorbent layer. The toilet paper is a low-grammage toilet paper with a weight of 11g / m²-13g / m², free of wet-strength agents. The absorbent layer is laid on the liquid-barrier layer, and then the absorbent layer is coated with a spiral, intermittent adhesive. The adhesive is a biodegradable, environmentally friendly hot melt adhesive. A4. Preparation of the surface layer and bonding it to the liquid-separating layer: The surface layer is a washable fabric layer, which is treated with a hydrophilic oil agent to achieve the effect of blood permeability. The surface layer is laid on the absorbent layer. A5. External perimeter sealing and pressing, cutting and shaping: The layers of top layer, absorbent layer, liquid-repellent layer and bottom layer are laminated together and then cut into individual sanitary napkin materials by cutting rollers. The outer perimeter sealing and pressing pattern consists of dense pressure point patterns, with each pressure point having a diameter of 2mm and a spacing of 1.5mm between them.

2. The method for manufacturing a flushable and biodegradable sanitary napkin according to claim 1, characterized in that: The washable fabric layer described in A1 and A4 is any one of the following: washable PLA (polylactic acid) hot-air nonwoven fabric, washable PLA (polylactic acid) direct-laid spunlace nonwoven fabric, washable PLA (polylactic acid) direct-laid spunlace nonwoven fabric, washable bamboo fiber direct-laid spunlace nonwoven fabric, and washable PHA (polyhydroxyalkanoate) direct-laid spunlace nonwoven fabric.

3. The method for manufacturing a flushable and biodegradable sanitary napkin according to claim 2, characterized in that: To improve the washout properties of PLA (polylactic acid) hot-air nonwoven fabric, the following parameters were adjusted: Weight 20g / ㎡-30g / ㎡, thickness 2.5mm-5mm, transverse breaking force ≥2.0N / 2 inches, transverse breaking elongation 70%-120%.

4. The method for manufacturing a flushable and biodegradable sanitary napkin according to claim 2, characterized in that: To improve the washability of PLA (polylactic acid) direct-laid spunlace nonwoven fabric, LA (polylactic acid) direct-laid spunlace nonwoven fabric, bamboo fiber direct-laid spunlace nonwoven fabric, or PHA (polyhydroxyalkanoate) direct-laid spunlace nonwoven fabric, the water pressure of the spunlace knife is adjusted during the direct-laying process to ensure that the transverse breaking force of the material reaches ≥3.0N / 2 inch, the transverse breaking elongation is 60%-110%, and the material weight is 30g / ㎡-35g / ㎡. Uneven thickness in some areas is allowed, but holes are not permitted.

5. The method for manufacturing a flushable and biodegradable sanitary napkin according to claim 1, characterized in that: The superabsorbent polymer (SAP) described in A3 is a sodium polyacrylate polymer with starch-embedded branches, and the sodium polyacrylate polymer is a catalyst bio-based polymer.

6. The method for manufacturing a flushable and biodegradable sanitary napkin according to claim 1, characterized in that: The superabsorbent polymer (SAP) described in A3 accounts for 6% of the mass of the intermediate absorbent layer.

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