Degradable waterproof paper diaper guard and preparation method thereof
By blending PLA and PBAT, and applying plant-based waterproofing agents and modified silanes, the contradiction between waterproofing and degradability of biodegradable diaper guards has been resolved, resulting in diaper guards with excellent waterproofing, good biodegradability, and stable composite properties, thus improving user comfort and environmental friendliness.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-29
- Publication Date
- 2026-04-14
AI Technical Summary
Existing biodegradable diaper guards present a contradiction between waterproofness, biodegradability, and mechanical properties, making it difficult to achieve both excellent waterproofness and good biodegradability. Furthermore, traditional chemical waterproofing agents may pose potential hazards to the environment and human health.
PLA and PBAT blends are used as the intermediate waterproof and biodegradable membrane substrate. Combined with plant wax waterproofing agent and modified silane, an outer layer of breathable non-woven fabric and an inner layer of skin-friendly non-woven fabric are laminated with environmentally friendly adhesive to form a multi-layer structure, which improves waterproofness, mechanical properties and biodegradability.
It achieves a balance between high waterproof performance and good biodegradability, avoiding environmental pollution and harm to the human body, improving the leak-proof effect and comfort of diapers, while maintaining the biodegradability of the materials.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of hygiene products technology, specifically to a biodegradable waterproof diaper guard and its preparation method. Background Technology
[0002] As a common hygiene product for infants and incontinent individuals, disposable diapers rely heavily on their side rails to prevent leakage. These rails must simultaneously possess waterproofness, softness, breathability, and a certain level of mechanical strength. Traditional disposable diaper side rails often use non-degradable plastic films such as polyethylene (PE) and polypropylene (PP) as the waterproof layer. While these materials offer excellent waterproofing, they are difficult to degrade in the natural environment, and their widespread use can easily cause serious white pollution, contradicting the principles of environmental protection. With increasingly stringent environmental policies and rising consumer awareness, the application of biodegradable materials in the hygiene product field has received widespread attention. Currently, the development of existing biodegradable disposable diaper side rails faces several technical bottlenecks: The balance between waterproofing and biodegradability is difficult to achieve: Existing biodegradable materials, such as pure polylactic acid (PLA) films, while exhibiting good degradation performance, suffer from insufficient hydrophobicity and poor waterproofing. Adding traditional chemical waterproofing agents (such as fluorinated waterproofing agents) can improve waterproofing, but it reduces the material's biodegradability, and fluorinated substances may pose potential hazards to human health and the environment. Insufficient mechanical properties: The flexibility and elongation at break of biodegradable polymers are generally lower than those of traditional plastics, making the resulting enclosures prone to damage during use due to stretching and bending, thus affecting leak-proof performance.
[0003] Therefore, developing a biodegradable waterproof diaper guard that combines excellent waterproofness, good biodegradability, stable composite properties, and a simple preparation process has become the key to solving industry pain points and meeting environmental protection and usage needs. Summary of the Invention
[0004] In order to overcome the shortcomings of the prior art, the present invention aims to provide a biodegradable waterproof diaper guard and its preparation method, thereby solving the problems of the contradiction between waterproofness and degradability and the insufficient mechanical properties of existing biodegradable guards.
[0005] To achieve the above objectives, the present invention employs the following technical solution: To achieve the above objectives, the present invention provides the following technical solution: a biodegradable waterproof diaper guard, characterized in that it comprises, from the outside to the inside, an outer breathable nonwoven fabric, a middle waterproof degradable membrane, and an inner skin-friendly nonwoven fabric, wherein the outer breathable nonwoven fabric, the middle waterproof degradable membrane, and the inner skin-friendly nonwoven fabric are composited and fixed by an environmentally friendly adhesive; the raw materials of the middle waterproof degradable membrane, by weight, are: 40-60 parts of polylactic acid (PLA), 20-30 parts of polybutylene adipate / terephthalate (PBAT), 2-5 parts of plant wax waterproofing agent, 1-3 parts of degradation promoter, and 1-1 parts of modified silane. 0.2 parts of PLA and 0.5-1.5 parts of antioxidant 1010; PLA and PBAT are blended as the membrane substrate. PLA provides good mechanical strength and degradation performance, while PBAT improves the material's flexibility and elongation at break. The ratio of the two is controlled at 2:1-3:1 to solve the problem of insufficient mechanical properties of a single biodegradable polymer; beeswax or carnauba wax is selected as a plant wax waterproofing agent to replace traditional fluorinated waterproofing agents, which improves hydrophobicity while avoiding environmental and human harm; modified silane is added to further enhance the waterproof effect of the membrane through interface modification, while also improving the composite adhesion between the membrane and the nonwoven fabric.
[0006] Furthermore, the outer breathable nonwoven fabric is a blend of biodegradable viscose fiber and cotton fiber (viscose fiber enhances degradation performance, cotton fiber strengthens mechanical strength and breathability; the blended structure balances breathability and moisture wicking with structural stability, allowing for rapid expulsion of moisture from the enclosure and preventing stuffiness), with a basis weight of 25-35. The inner layer of skin-friendly non-woven fabric is made of bamboo fiber (bamboo fiber naturally possesses soft, breathable, and antibacterial properties, and is biodegradable; it reduces friction and irritation when in direct contact with the skin, improving comfort), with a weight of 20-30 g / m². .
[0007] Furthermore, the plant-based wax waterproofing agent is one of beeswax or carnauba wax.
[0008] Furthermore, the method for preparing the modified silane is as follows: S1. Add 2.6-2.8 mL of trimercaptopropyltrimethoxysilane to 105-110 mL of methanol, and then slowly add 10-12 mL of 36% HCl dropwise to the reaction system. After the addition is complete, heat the reaction mixture to reflux and maintain the reaction for 18-22 h. After the reaction is complete, cool to room temperature, wash with ice-cold methanol, freeze overnight, and discard the supernatant to obtain mercapto-modified silane. S2. Thiol-modified silane, methyl acrylate, and 2,2-dimethoxy-2-phenylacetophenone were added to 35-45 mL of ultra-dry dichloromethane and reacted under 365 nm UV light. After the reaction was completed, the mixture was washed and dried to obtain the modified silane. Methyl acrylate grafting endowed the silane with lipophilicity, improving its compatibility with PLA / PBAT substrates, thereby enhancing the structural stability and waterproof performance of the waterproof membrane.
[0009] Further, in S2, the ratio of mercapto-modified silane, methyl acrylate, and 2,2-dimethoxy-2-phenylacetophenone is 0.45-0.55 mmol: 1.3-1.4 mmol: 0.01-0.014 mmol.
[0010] Furthermore, in S2, the reaction time under ultraviolet light irradiation is 8-9 hours.
[0011] Furthermore, the method for preparing the biodegradable waterproof diaper guard is as follows: (1) Substrate pretreatment: The outer breathable non-woven fabric and the inner skin-friendly non-woven fabric are subjected to plasma treatment. The treatment power is 30-50W and the treatment time is 30-60s to improve the adhesion of the substrate surface. (2) Preparation of intermediate waterproof and degradable membrane: Ingredient mixing: Weigh out polylactic acid, poly(butylene adipate / terephthalate), plant wax waterproofing agent, degradation accelerator, modified silane, and antioxidant 1010 by weight and put them into a twin-screw extruder. Melt blend at 160-180℃, and extrude and granulate to obtain composite masterbatch. Film blowing: The composite masterbatch is put into the film blowing machine, the blowing temperature is set to 150-170℃, the blow-up ratio is 2.5-3.5, and the traction speed is 5-10m / min to obtain the intermediate waterproof and degradable film. (5) Multi-layer composite: Using a three-roller composite machine, an environmentally friendly adhesive is coated on one side of the outer breathable non-woven fabric, and the middle waterproof degradable membrane is bonded together. Then, an environmentally friendly adhesive is coated on the other side of the middle waterproof degradable membrane, and the inner skin-friendly non-woven fabric is bonded together. The composite pressure is 0.3-0.5MPa, and the composite temperature is 60-80℃. (6) Embossing: The composite substrate is fed into an embossing machine, and a diamond embossing pattern is used. The embossing depth is 0.1-0.3mm and the embossing temperature is 50-70℃ to improve the structural stability and breathability of the enclosure. (5) Cutting and shaping: According to the size requirements of the diaper guard, the guard is precisely cut by a cutting machine. After cutting, it is hot air shaped. The shaped temperature is 70-90℃ and the shaped time is 1-2 minutes to obtain the biodegradable waterproof diaper guard.
[0012] Furthermore, in step (3), the coating amount of the environmentally friendly adhesive is 5-10g. .
[0013] Compared with the prior art, the present invention has the following beneficial technical effects: This invention relates to a waterproof and biodegradable membrane in the middle of a diaper. It abandons traditional fluorinated waterproofing agents and instead uses beeswax or carnauba wax as a plant-based waterproofing agent. These natural extracts possess excellent hydrophobic properties, forming a dense waterproof layer on the surface of the membrane. Simultaneously, they are completely biodegradable, leaving no environmental pollutants and avoiding the potential irritation of human skin caused by fluorinated substances. The core substrate of the membrane is a blend of PLA and PBAT in a 2:1-3:1 ratio. Both are fully biodegradable polymers with strong molecular structural complementarity, avoiding the problems of easy cracking during the degradation of single PLA films or the excessively rapid degradation of single PBAT films. Combined with polyethylene glycol 400 as a degradation promoter, it exhibits good degradation effects, reducing white pollution at its source.
[0014] In the technical solution of this invention, the modified silane, after graft modification with methyl acrylate, possesses both hydrophobic and lipophilic properties: the hydrophobic groups in its molecular structure can form a dense hydrophobic layer on the surface of the waterproof membrane, filling the micropores inside the PLA / PBAT blend substrate and reducing water penetration channels; simultaneously, its lipophilicity allows it to form good compatibility with the molecular chains of PLA and PBAT, avoiding waterproofing leaks caused by poor interfacial bonding between the additives and the substrate, thereby synergistically enhancing the hydrostatic pressure value of the intermediate waterproof degradation membrane and strengthening the overall leak-proof effect of the enclosure. In the PLA and PBAT blend system, the compatibility of their molecular chains has certain limitations, easily leading to uneven internal structure of the membrane material and affecting mechanical properties. The modified silane can act as an interfacial compatibilizer; its lipophilic segments can insert between the molecular chains of PLA and PBAT, reducing the interfacial tension between the two phases and promoting the formation of a uniform blend structure between PLA and PBAT. Detailed Implementation To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0015] The environmentally friendly adhesive is an environmentally friendly hot melt pressure-sensitive adhesive (HMPSA), prepared according to the reference "Development of Environmentally Friendly Hot Melt Pressure-Sensitive Adhesive for Hygiene Products". Tackifier, plasticizer, and antioxidant are added to a three-necked flask equipped with a stirrer, thermometer, and nitrogen inlet pipe. Heating is performed while nitrogen is introduced for protection, maintaining the temperature at approximately 120°C. When the tackifier is mostly melted, stirring is slowly started until it is completely melted. Then, while maintaining nitrogen and stirring, the temperature is raised to 160°C–180°C, and thermoplastic elastomer is added in batches until the thermoplastic elastomer is completely dissolved and the entire system becomes a uniform, transparent, viscous liquid. Heating and stirring are then stopped, and the mixture is discharged while hot. It is then allowed to cool and set naturally in a setting box lined with release paper (the size of the setting box is determined according to actual needs) before packaging.
[0016] Poly(butylene adipate) / Terephthalate: Hangzhou Xinfu Pharmaceutical Co., Ltd.
[0017] Degradation accelerator: Polyethylene glycol 400.
[0018] Polylactic acid: Number average molecular weight (Mn) 60000.
[0019] Example 1 Core raw material formula (by weight): 40 parts polylactic acid, 30 parts polybutylene adipate / terephthalate, 2 parts plant wax waterproofing agent (beeswax selected), 1 part degradation accelerator (polyethylene glycol 400), 1.0 part modified silane, 0.5 parts antioxidant 10100; the outer breathable non-woven fabric is a blend of biodegradable viscose fiber and cotton fiber (weight ratio 1:1), with a basis weight of 25. The inner layer of skin-friendly non-woven fabric is made of bamboo fiber, with a weight of 20 g / m². The environmentally friendly adhesive used is an environmentally friendly hot melt pressure-sensitive adhesive (HMPSA).
[0020] Preparation of modified silanes: S1: Take 2.6 mL of trimercaptopropyltrimethoxysilane and add it to 105 mL of methanol. Slowly add 10 mL of 36% HCl. After the addition is complete, heat to reflux and maintain the reaction for 18 h. After cooling to room temperature, wash with ice-cold methanol, freeze overnight, and discard the supernatant to obtain mercapto-modified silane. S2: The three components were added to 35 mL of ultra-dry dichloromethane according to the following ratio: 0.45 mmol of mercapto-modified silane, 1.3 mmol of methyl acrylate, and 0.01 mmol of 2,2-dimethoxy-2-phenylacetophenone. The mixture was reacted under 365 nm ultraviolet light for 8 h. After the reaction was completed, the silane was obtained by washing and drying.
[0021] Preparation process: Substrate pretreatment: The outer breathable non-woven fabric and the inner skin-friendly non-woven fabric are subjected to plasma treatment with a power of 30W and a treatment time of 30s. Preparation of intermediate waterproof biodegradable membrane: Weigh the raw materials according to the formula and put them into a twin-screw extruder. Melt and blend them at 160℃, and extrude and granulate them to obtain composite masterbatch. Put the composite masterbatch into a blown film machine and set the blown film temperature to 150℃, the blown ratio to 2.5, and the traction speed to 5m / min to obtain the intermediate waterproof biodegradable membrane. Multi-layer lamination: Using a three-roll laminator, an environmentally friendly adhesive is coated onto the outer breathable non-woven fabric side (coating amount 5). The middle waterproof and biodegradable membrane is laminated, and the same environmentally friendly adhesive is applied to the other side of the middle waterproof and biodegradable membrane. The inner skin-friendly non-woven fabric is then laminated, with a lamination pressure of 0.3MPa and a lamination temperature of 60℃. Embossing: The composite substrate is fed into an embossing machine, a diamond embossing pattern is used, the embossing depth is 0.1mm, and the embossing temperature is 50℃; Cutting and shaping: Cut precisely according to the size of the diaper guards, and then perform hot air shaping treatment at a temperature of 70℃ for 1 minute to obtain the finished product.
[0022] Example 2 Core raw material formula (by weight): 50 parts polylactic acid, 25 parts polybutylene adipate / terephthalate, 3 parts plant wax waterproofing agent (carnauba wax selected), 2 parts degradation accelerator (polyethylene glycol 400), 1.1 parts modified silane, 1.0 parts antioxidant 1010; the outer breathable non-woven fabric is a blend of biodegradable viscose fiber and cotton fiber (weight ratio 1:1), with a basis weight of 30 g / m². The inner layer of skin-friendly non-woven fabric is made of bamboo fiber, with a weight of 25g / m². The environmentally friendly adhesive used is an environmentally friendly hot melt pressure-sensitive adhesive (HMPSA).
[0023] Preparation of modified silanes: S1: Take 2.7 mL of trimercaptopropyltrimethoxysilane and add it to 108 mL of methanol. Slowly add 11 mL of 36% HCl. After the addition is complete, heat to reflux and maintain the reaction for 20 h. After cooling to room temperature, wash with ice-cold methanol, freeze overnight, and discard the supernatant to obtain mercapto-modified silane. S2: The three components were added to 40 mL of ultra-dry dichloromethane in the following ratio: 0.5 mmol of mercapto-modified silane, 1.35 mmol of methyl acrylate, and 0.012 mmol of 2,2-dimethoxy-2-phenylacetophenone. The mixture was reacted under 365 nm UV light for 8.5 h. After the reaction was completed, the silane was obtained by washing and drying.
[0024] Preparation process: Substrate pretreatment: The outer breathable non-woven fabric and the inner skin-friendly non-woven fabric are subjected to plasma treatment with a power of 40W and a treatment time of 45s. Preparation of intermediate waterproof biodegradable membrane: Weigh the raw materials according to the formula and put them into a twin-screw extruder. Melt and blend them at 170℃, and then extrude and granulate them to obtain composite masterbatch. Put the composite masterbatch into a blown film machine and set the blown film temperature to 160℃, the blown ratio to 3.0, and the traction speed to 8m / min to obtain the intermediate waterproof biodegradable membrane. Multi-layer lamination: Using a three-roll laminator, an environmentally friendly adhesive is coated onto the outer breathable non-woven fabric side (coating amount 8). The middle waterproof and biodegradable membrane is laminated, and the same environmentally friendly adhesive is applied to the other side of the middle waterproof and biodegradable membrane. The inner skin-friendly non-woven fabric is then laminated, with a lamination pressure of 0.4MPa and a lamination temperature of 70℃. Embossing: The composite substrate is fed into an embossing machine, a diamond embossing pattern is used, the embossing depth is 0.2mm, and the embossing temperature is 60℃; Cutting and shaping: Cut precisely according to the size of the diaper guards, and then perform hot air shaping treatment at a temperature of 80℃ for 1.5 minutes to obtain the finished product.
[0025] Example 3 Core raw material formula (by weight): 60 parts polylactic acid, 20 parts polybutylene adipate / terephthalate, 5 parts plant wax waterproofing agent (beeswax selected), 3 parts degradation accelerator (polyethylene glycol 400), 1.2 parts modified silane, 1.5 parts antioxidant 1010; the outer breathable non-woven fabric is a blend of biodegradable viscose fiber and cotton fiber (weight ratio 1:1), with a basis weight of 35. The inner layer of skin-friendly non-woven fabric is made of bamboo fiber, with a weight of 30 g / m². The environmentally friendly adhesive used is an environmentally friendly hot melt pressure-sensitive adhesive (HMPSA).
[0026] Preparation of modified silanes: S1: Take 2.8 mL of trimercaptopropyltrimethoxysilane and add it to 110 mL of methanol. Slowly add 12 mL of 36% HCl. After the addition is complete, heat to reflux and maintain the reaction for 22 h. After cooling to room temperature, wash with ice-cold methanol, freeze overnight, and discard the supernatant to obtain mercapto-modified silane. S2: The three components were added to 45 mL of ultra-dry dichloromethane according to the following ratio: 0.55 mmol of mercapto-modified silane, 1.4 mmol of methyl acrylate, and 0.014 mmol of 2,2-dimethoxy-2-phenylacetophenone. The mixture was reacted under a 365 nm UV lamp for 9 h. After the reaction was completed, the silane was obtained by washing and drying.
[0027] Preparation process: Substrate pretreatment: The outer breathable non-woven fabric and the inner skin-friendly non-woven fabric are subjected to plasma treatment with a power of 50W and a treatment time of 60s. Preparation of intermediate waterproof biodegradable membrane: Weigh the raw materials according to the formula and put them into a twin-screw extruder. Melt and blend them at 180°C, and extrude and granulate them to obtain composite masterbatch. Put the composite masterbatch into a blown film machine and set the blown film temperature to 170°C, the blown ratio to 3.5, and the traction speed to 10m / min to obtain the intermediate waterproof biodegradable membrane. Multi-layer lamination: Using a three-roll laminator, an environmentally friendly adhesive is coated onto the outer breathable non-woven fabric side (coating amount 10). The middle waterproof and biodegradable membrane is laminated, and the same environmentally friendly adhesive is applied to the other side of the middle waterproof and biodegradable membrane. The inner skin-friendly non-woven fabric is then laminated, with a lamination pressure of 0.5MPa and a lamination temperature of 80℃. Embossing: The composite substrate is fed into an embossing machine, a diamond embossing pattern is used, the embossing depth is 0.3mm, and the embossing temperature is 70℃; Cutting and shaping: Cut precisely according to the size of the diaper guards, and then perform hot air shaping treatment at a temperature of 90℃ for 2 minutes to obtain the finished product.
[0028] Comparative Example 1 The difference between this comparative example and Example 3 is that no plant-based wax waterproofing agent was added.
[0029] Comparative Example 2 The difference between this comparative example and Example 3 is that no degradation accelerator was added.
[0030] Comparative Example 3 The difference between this comparative example and Example 3 is that no modified silane was added.
[0031] Comparative Example 4 The difference between this comparative example and Example 3 is that the core substrate was replaced.
[0032] The composition includes 60 parts polylactic acid, 20 parts polybutylene adipate / terephthalate, 5 parts plant wax waterproofing agent (beeswax), 3 parts degradation accelerator (polyethylene glycol 400), 1.2 parts modified silane, and 1.5 parts antioxidant 1010; the outer breathable nonwoven fabric is pure viscose fiber nonwoven fabric (35 g / m²). The inner layer of skin-friendly non-woven fabric is made of polypropylene (PP) non-woven fabric (30 g / m²). ); Environmentally friendly adhesives are selected, specifically environmentally friendly hot melt pressure-sensitive adhesives.
[0033] Table 1: Performance Tests
[0034] Table 1 shows that the hydrostatic pressure values of Examples 1-3 were 2.4 kPa, 2.2 kPa, and 2.5 kPa, respectively, generally remaining above 2.2 kPa. Comparative Example 1 (without plant wax waterproofing agent) had a hydrostatic pressure of only 0.7 kPa, Comparative Example 3 (without modified silane) had 1.2 kPa, Comparative Example 4 (with replacement of the core substrate) had 2.2 kPa, and Comparative Example 2 (without degradation accelerator) had 2.3 kPa. Analysis conclusion: Plant wax waterproofing agent is the core guarantee of waterproof performance: Comparative Example 1, lacking plant wax waterproofing agent, experienced a sharp drop in hydrostatic pressure of 72% (compared to Example 3), proving that beeswax / carnauba wax can form a dense hydrophobic layer on the surface of the intermediate film, directly determining the waterproof barrier effect. Modified silane plays a synergistic reinforcing role: In Comparative Example 3 without modified silane, the hydrostatic pressure decreased by 52% compared to Example 3, demonstrating the key role of modified silane in filling substrate pores, improving compatibility with PLA / PBAT, and further reducing water penetration channels. The degradation accelerator and substrate replacement had minimal impact on water resistance: the water resistance of Comparative Examples 2 and 4 was not significantly different from that of Example 3, indicating that these two variables did not damage the hydrophobic structure of the intermediate membrane.
[0035] Examples 1-3 showed degradation rates of 80%, 78%, and 82%, respectively, all reaching a high degradation level of approximately 80%. Comparative Example 2 (without degradation accelerator) showed only 55%, Comparative Example 4 (with replaced core substrate) showed 60%, and Comparative Examples 1 (without plant wax waterproofing agent) and 3 (without modified silane) showed 76% and 75%, respectively. Analysis conclusion: The degradation accelerator (polyethylene glycol 400) is key to improving the degradation rate: Comparative Example 2, lacking this component, showed a 33% decrease in degradation rate compared to Example 3, verifying its effective regulation of the PLA / PBAT degradation process and avoiding the slow degradation problem of a single degradable polymer. Substrate compatibility directly affects the overall degradation rate: Comparative Example 4, with its inner layer made of non-degradable PP nonwoven fabric and the outer layer of pure viscose fiber nonwoven fabric, showed a 27% decrease in degradation rate compared to Example 3, proving that the combination of the outer layer blended nonwoven fabric (viscose fiber + cotton fiber) and the inner layer of bamboo fiber nonwoven fabric is an important prerequisite for ensuring the overall degradability of the enclosure. Plant wax waterproofing agent and modified silane do not affect degradation performance: The degradation rates of Comparative Examples 1 and 3 are close to those of Example 3, indicating that these two additives are biodegradable and do not introduce impurities that are difficult to degrade, thus achieving synergistic compatibility between waterproofing and degradation.
[0036] Elongation at break: Examples 1-3 were 195%, 186%, and 200%, respectively; Comparative Example 3 (without modified silane) was only 110%; Comparative Example 4 (with replaced core substrate) was 174%; Comparative Examples 1 and 2 showed little difference from Example 3 (195% and 190%, respectively). Tensile strength: Examples 1-3 were 16 MPa, 15 MPa, and 18 MPa, respectively; Comparative Example 3 was 9.2 MPa; Comparative Example 4 was 10.8 MPa; Comparative Examples 1 and 2 were 17 MPa and 17.5 MPa, respectively. Analysis conclusion: Modified silane plays a decisive role in mechanical properties: In Comparative Example 3 without modified silane, tensile strength decreased by 49% and elongation at break decreased by 45%. This is because modified silane, as an interfacial compatibilizer, can reduce the interfacial tension between PLA and PBAT, prevent phase separation, and improve the uniformity of the membrane structure. Without modified silane, the internal structure of the membrane is loose, resulting in insufficient mechanical support. The substrate composition affects structural stability: In Comparative Example 4, replacing the outer layer with pure viscose fiber and the inner layer with PP resulted in a 40% decrease in tensile strength and a 13% decrease in elongation at break. This is because the mechanical reinforcement of the cotton fibers in the outer blended nonwoven fabric and the tough support of the bamboo fibers in the inner layer were weakened, leading to a decline in overall tensile and bending resistance. Plant wax waterproofing agents and degradation accelerators have no significant effect on mechanical properties: The mechanical properties of Comparative Examples 1 and 2 are similar to those of Example 3, indicating that the addition of these two components did not disrupt the PLA / PBAT blend structure and did not affect the mechanical properties of the substrate itself.
[0037] Examples 1-3 have an air permeability of 104 L / ( •s), 98L / ( •s), 110L / ( •s), Comparative Example 4 (replacing the core substrate) is 75L / ( •s), comparative examples 1, 2, and 3 were 108L, 105L, and 85L / ( •s). Analysis conclusion: The type of substrate is the core influencing factor of air permeability: The outer layer of blended nonwoven fabric (viscose fiber + cotton fiber) used in the example has natural interwoven air permeability channels, and the inner layer of bamboo fiber nonwoven fabric is breathable. However, the pure viscose fiber outer layer of Comparative Example 4 has a simple air permeability structure and poor air permeability of the PP inner layer, resulting in a 32% decrease in air permeability compared with Example 3.
[0038] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.
[0039] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.
[0040] Those skilled in the art should understand that the above descriptions are merely several specific embodiments of the present invention, and not all embodiments.
Claims
1. A biodegradable waterproof diaper guard, characterized in that, From the outside to the inside, it comprises an outer layer of breathable non-woven fabric, a middle layer of waterproof and degradable membrane, and an inner layer of skin-friendly non-woven fabric. The outer layer of breathable non-woven fabric, the middle layer of waterproof and degradable membrane, and the inner layer of skin-friendly non-woven fabric are bonded together with an environmentally friendly adhesive. The raw materials of the middle waterproof and degradable membrane are, by weight, 40-60 parts of polylactic acid, 20-30 parts of poly(butylene adipate / terephthalate), 2-5 parts of plant wax waterproofing agent, 1-3 parts of degradation promoter, 1-1.2 parts of modified silane, and 0.5-1.5 parts of antioxidant 1010.
2. The biodegradable waterproof diaper guard according to claim 1, characterized in that, The outer breathable nonwoven fabric is a blend of biodegradable viscose fiber and cotton fiber, with a basis weight of 25-35. The inner layer of skin-friendly non-woven fabric is made of bamboo fiber, with a basis weight of 20-30 g / m². .
3. The biodegradable waterproof diaper guard according to claim 1, characterized in that, The plant-based waterproofing agent is one of beeswax or carnauba wax.
4. The biodegradable waterproof diaper guard according to claim 1, characterized in that, The method for preparing the modified silane is as follows: S1. Add 2.6-2.8 mL of trimercaptopropyltrimethoxysilane to 105-110 mL of methanol, and then slowly add 10-12 mL of 36% HCl dropwise to the reaction system. After the addition is complete, heat the reaction mixture to reflux and maintain the reaction for 18-22 h. After the reaction is complete, cool to room temperature, wash with ice-cold methanol, freeze overnight, and discard the supernatant to obtain mercapto-modified silane. S2. Add mercapto-modified silane, methyl acrylate, and 2,2-dimethoxy-2-phenylacetophenone to 35-45 mL of ultra-dry dichloromethane and react under 365 nm ultraviolet light. After the reaction is complete, wash and dry to obtain modified silane.
5. The biodegradable waterproof diaper guard according to claim 4, characterized in that, In S2, the ratio of mercapto-modified silane, methyl acrylate, and 2,2-dimethoxy-2-phenylacetophenone is 0.45-0.55 mmol: 1.3-1.4 mmol: 0.01-0.014 mmol.
6. The biodegradable waterproof diaper guard according to claim 4, characterized in that, In S2, the reaction time under ultraviolet light irradiation is 8-9 hours.
7. A method for preparing a biodegradable waterproof diaper guard as described in any one of claims 1-6, characterized in that, The method for preparing the biodegradable waterproof diaper guard is as follows: (1) Substrate pretreatment: The outer breathable non-woven fabric and the inner skin-friendly non-woven fabric are subjected to plasma treatment. The treatment power is 30-50W and the treatment time is 30-60s to improve the adhesion of the substrate surface. (2) Preparation of intermediate waterproof and degradable membrane: Ingredient mixing: Weigh out polylactic acid, poly(butylene adipate / terephthalate), plant wax waterproofing agent, degradation accelerator, modified silane, and antioxidant 1010 by weight and put them into a twin-screw extruder. Melt blend at 160-180℃, and extrude and granulate to obtain composite masterbatch. Film blowing: The composite masterbatch is put into the film blowing machine, the blowing temperature is set to 150-170℃, the blow-up ratio is 2.5-3.5, and the traction speed is 5-10m / min to obtain the intermediate waterproof and degradable film. (3) Multilayer composite: Using a three-roller composite machine, an environmentally friendly adhesive is coated on one side of the outer breathable nonwoven fabric, and the middle waterproof degradable membrane is bonded together. Then, an environmentally friendly adhesive is coated on the other side of the middle waterproof degradable membrane, and the inner skin-friendly nonwoven fabric is bonded together. The composite pressure is 0.3-0.5MPa, and the composite temperature is 60-80℃. (4) Embossing: The composite substrate is fed into an embossing machine, and a diamond embossing pattern is used. The embossing depth is 0.1-0.3mm and the embossing temperature is 50-70℃ to improve the structural stability and breathability of the enclosure. (5) Cutting and shaping: According to the size requirements of the diaper guard, the guard is precisely cut by a cutting machine. After cutting, it is hot air shaped. The shaped temperature is 70-90℃ and the shaped time is 1-2 minutes to obtain the biodegradable waterproof diaper guard.
8. The method for preparing the biodegradable waterproof diaper guard according to claim 7, characterized in that, In step (3), the amount of environmentally friendly adhesive applied is 5-10g. .