Anti-yellowing high-breathability three-dimensional molded mask and preparation method thereof
By combining a three-layer three-dimensional molded mask structure with specific adhesives, the problems of poor breathability and yellowing have been solved, achieving high breathability and anti-yellowing effects, and improving the mask's aesthetics and wearing comfort.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHENZHEN MINUS TECH CO LTD
- Filing Date
- 2026-04-01
- Publication Date
- 2026-06-09
AI Technical Summary
Existing 3D molded masks have poor breathability and are prone to yellowing, especially under light, which affects their appearance and wearing comfort.
The three-layer molded mask consists of an outer layer, an inner layer, and a middle support layer. The middle support layer has a three-dimensional mesh structure and is bonded with adhesive to form an anti-yellowing sealing layer at the cut edges. The adhesive contains aliphatic PUR prepolymer, antioxidant system, and UV absorber, combined with physical pore-forming agents to improve breathability and light resistance.
It achieves high breathability and anti-yellowing performance of the mask, solving the problems of poor breathability and easy yellowing, and improving the aesthetics and comfort of wearing.
Smart Images
Figure CN122163002A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of personal protective equipment technology, and in particular to an anti-yellowing, highly breathable, three-dimensional molded mask and its preparation method. Background Technology
[0002] In recent years, with the public's increasing demands for both respiratory protection and the aesthetics of everyday clothing, 3D molded masks have gradually become the mainstream choice in the market due to their advantages such as a firm cavity structure, a close fit to facial contours, and resistance to lip makeup staining. However, currently, the one-piece molded masks on the market are basically derivative products of bra manufacturing processes and have not been designed and produced with a high degree of precision to meet people's specific respiratory and protective needs for masks.
[0003] Current molding mask manufacturing processes typically use hot melt adhesive film or ordinary liquid resin as the bonding layer to fully composite multiple layers of non-woven fabric, sponge, and other substrates, which are then placed in a specific mold for high-temperature and high-pressure molding. However, molded masks on the market generally suffer from poor breathability, are bulky, and stuffy, making them extremely unsuitable for wearing in the warm spring and summer seasons. Furthermore, existing molded masks are not resistant to sunlight and easily turn yellow after exposure to natural light, a problem that is particularly pronounced during outdoor activities and prolonged exposure in summer.
[0004] In summary, there is an urgent need in this field to provide a three-dimensional molded mask that can maintain the three-dimensional support of the cavity, as well as have good breathability and excellent anti-yellowing performance. Summary of the Invention
[0005] The technical problem to be solved by the present invention is that existing three-dimensional molded masks have poor breathability and are prone to yellowing.
[0006] To address the above problems, the present invention proposes the following technical solution: In a first aspect, the present invention provides an anti-yellowing, highly breathable, three-dimensional molded mask, comprising: The outer mask body is composed of a surface layer, a middle support layer, and an inner layer, which are molded together. The intermediate support layer has a three-dimensional mesh structure; The surface layer and the intermediate support layer, as well as the intermediate support layer and the inner layer, are bonded together by adhesive. The adhesive, by weight, comprises: 100 parts aliphatic PUR prepolymer, 0.3-1.5 parts antioxidant system, 0.5-2.0 parts ultraviolet absorber, and 0.5-3.0 parts physical pore-forming agent; The edge contours of the intermediate support layer are all smaller than the edge contours of the surface layer and the inner layer, so that the edge of the surface layer and the edge of the inner layer are in direct contact and are sealed by adhesive. Meanwhile, the adhesive penetrates into the cut edge of the intermediate support layer, wraps and fixes the cut edge of the intermediate support layer, and after curing, forms an anti-yellowing encapsulation layer that extends continuously along the cut edge of the intermediate support layer.
[0007] A further technical solution is that one or more first openings are provided on the surface layer, and one or more second openings are provided on the inner layer; the adhesive penetrates into the intermediate support layer at the cut edges of each of the first openings and / or each of the second openings, and after curing, forms an anti-yellowing encapsulation layer that extends continuously along the cut edges of the first openings and / or each of the second openings.
[0008] A further technical solution is that the edge contour of the intermediate support layer is 1-2 mm smaller than the edge contours of the surface layer and the inner layer.
[0009] A further technical solution is that the antioxidant system includes hindered phenolic antioxidants and phosphite antioxidants, with a mass ratio of 6:4 to 7:3.
[0010] A further technical solution is that the isocyanate raw material of the aliphatic PUR prepolymer is selected from one or more of isophorone diisocyanate (IPDI) and hexamethylene diisocyanate (HDI).
[0011] A further technical solution is that the physical porogen is a micron-sized thermally expandable microsphere; and the adhesive, after curing, has micropores inside formed by the thermal expansion or decomposition of the physical porogen.
[0012] A further technical solution is that the adhesive is distributed in a dotted or grid-like pattern in the non-cut edge areas of the surface layer, intermediate support layer and / or inner layer.
[0013] A further technical solution is that the width of the anti-yellowing encapsulation layer is 3-5mm.
[0014] A further technical solution includes an inner beaded pad, which is attached to the inner surface of the outer mask body and is located at the position corresponding to the bridge of the nose and / or cheek when worn.
[0015] Secondly, the present invention provides a method for preparing a three-dimensional molded mask with anti-yellowing and high breathability, comprising the following steps: S1. Preparation of adhesive: By weight, heat 100 parts of aliphatic PUR prepolymer to a molten state, add 0.3~1.5 parts of antioxidant system, 0.5~2.0 parts of ultraviolet absorber, and 0.5~3.0 parts of physical pore-forming agent and mix evenly; S2. Coating: The prepared adhesive is applied to the inner surface of the outer fabric, both surfaces of the sandwich fabric, and the inner surface of the inner fabric. S3. Hot-press lamination: The coated surface fabric, the middle support layer fabric, and the inner fabric are stacked in sequence and placed in a positioning mold for the first hot pressing, so that the surface fabric, the middle support layer fabric, and the inner fabric are bonded together. S4. Molding and shaping: The composite sheet obtained in step S3 is placed in a three-dimensional mask mold for a second hot pressing to form the outer mask body with a three-dimensional shape.
[0016] Further, in step S2, the adhesive is continuously applied to the cut edge areas of the surface fabric, the intermediate support layer fabric, and / or the inner fabric; the adhesive is applied in a dotted or grid pattern to the non-cut edge areas of the surface fabric, the intermediate support layer fabric, and / or the inner fabric.
[0017] Furthermore, the coverage of dotted or grid-like coatings accounts for 20% to 35% of the total area of one side of the fabric, and the coating amount on one side is controlled at 5 g / m². 2 ~12g / m 2 It retains more than 65% of the original fiber porosity.
[0018] Furthermore, before the coating step S2, a fabric preparation step is also included: cutting the outer layer fabric, sandwich fabric and inner layer fabric according to the design pattern, so that the edge contour of the middle support layer fabric is smaller than the edge contour of the outer layer and the edge contour of the inner layer.
[0019] Furthermore, in step S3, the temperature of the first hot pressing is 165-175℃ and the time is 50-60 seconds; in step S4, the temperature of the second hot pressing is 165-175℃ and the time is 50-60 seconds.
[0020] Furthermore, it also includes: step S5, preparation of inner bean pad: after the inner fabric is combined with the sponge, it is placed in the bean mold for molding and shaping to form an inner bean pad with a three-dimensional raised structure. Step S6, Assembly: Attach the inner bean pad to the preset position of the inner fabric and perform a third hot pressing fixation at a temperature of 155-165℃ for 45-55 seconds.
[0021] Compared with the prior art, the technical effects achieved by the present invention include: The anti-yellowing, highly breathable, three-dimensional molded mask provided by this invention employs a three-dimensional structure composed of an outer layer, a middle support layer (with a mesh structure), and an inner layer, all molded together. A sandwich fabric with a three-dimensional mesh structure serves as the supporting skeleton, ensuring the mask's three-dimensional shape and preventing it from sticking to the mouth while providing ample airflow channels and excellent breathability. Furthermore, the adhesive of this invention uses aliphatic PUR prepolymer as the base resin, combined with an antioxidant system, ultraviolet absorbers, and physical pore-forming agents to form multiple layers of protection against photoaging and thermo-oxidative aging. This improves the weather resistance of the adhesive and the overall mask, solving the problem of incomplete protection from single anti-yellowing methods.
[0022] The present invention provides an anti-yellowing, highly breathable, three-dimensional molded mask. The edge contours of the intermediate support layer are all smaller than those of the surface layer and the inner layer, allowing the edges of the surface layer and the inner layer to directly contact and be sealed together with adhesive. Simultaneously, the adhesive penetrates the cut edges of the intermediate support layer, wrapping and fixing them. After curing, it forms an anti-yellowing encapsulation layer that continuously extends along the cut edges of the intermediate support layer. This avoids direct exposure of the edges of the intermediate support layer fabric. Furthermore, the adhesive penetrates into the mesh of the intermediate support layer fabric edges, wrapping and fixing the cut edges. The adhesive's sealing protection of the cut edges prevents moisture and oxygen from intruding, improving the anti-yellowing ability of the edge area. It also eliminates the itching sensation caused by the cut edges contacting the skin. This solves the problem of existing molded masks being unable to simultaneously address the issues of poor yellowing resistance, edge itching, and poor breathability, resulting in a three-dimensional molded mask product that combines long-lasting aesthetics, skin-friendly comfort, and high breathability.
[0023] The present invention provides a method for preparing an anti-yellowing, highly breathable, three-dimensional molded mask by applying an adhesive between the surface fabric and the intermediate support layer fabric, and between the intermediate support layer fabric and the inner fabric. The adhesive is continuously applied to the cut edge areas with a higher amount than that in the middle areas. Dotted or grid-like coatings are applied to the areas corresponding to the center of the mask. Through differentiated coating in different areas, sufficient adhesive is obtained in the edge areas to form an encapsulation layer, while the middle areas retain breathable pores, thereby improving the breathability of the final product. Attached Figure Description
[0024] Figure 1 A photograph of the outer surface of the anti-yellowing, highly breathable, three-dimensional molded mask provided in an embodiment of the present invention; Figure 2 Photograph of the inner surface of an anti-yellowing, highly breathable, three-dimensional molded mask provided in another embodiment of the present invention; Figure 3The fabric shapes of the outer layer, inner layer, and middle support layer of the anti-yellowing, high-breathability, three-dimensional molded mask provided in the embodiments of the present invention are, from left to right, the outer layer, the inner layer, and the middle support layer; Figure 4 A photograph of the outer surface of the mask body during the first molding in the preparation method of the anti-yellowing, high-breathability, three-dimensional molded mask provided in the embodiment of the present invention; Figure 5 This is a photograph of the outer surface of the mask body after the second molding in the preparation method of the anti-yellowing, high-breathability, three-dimensional molded mask provided in the embodiment of the present invention; Figure 6 Photograph of the bean liner provided for another embodiment of the present invention; Figure 7 A photograph showing the composite of the bean-shaped inner lining and the inner surface of the mask body, provided for another embodiment of the present invention; Detailed Implementation
[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.
[0026] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.
[0027] It should also be understood that the terminology used in this specification of embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to limit the embodiments of the invention. As used in this specification of embodiments of the invention and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.
[0028] See Figure 1 This invention provides an anti-yellowing, highly breathable, three-dimensional molded mask, comprising: The outer mask body is a three-dimensional structure composed of a surface layer, a middle support layer, and an inner layer, which are molded together. The middle support layer has a three-dimensional mesh structure. The surface layer and the middle support layer, as well as the middle support layer and the inner layer, are bonded together with adhesive.
[0029] In practice, the middle support layer is made of sandwich fabric.
[0030] See Figure 2 To further improve the comfort of the mask fit to the face, especially in areas requiring local cushioning such as the bridge of the nose and cheeks, another embodiment of the present invention provides an anti-yellowing, high-breathability, three-dimensional molded mask that, in addition to the aforementioned embodiments, also includes an inner layer of pimple padding. The inner layer of pimple padding is an independently prepared three-dimensional protruding structure that is subsequently attached to a preset position on the inner surface of the outer mask body, for example, in the wearing state, it is located at the position corresponding to the bridge of the nose and / or cheeks of the human body.
[0031] Figure 1 and Figure 2 In this invention, the edge region of the anti-yellowing, highly breathable, three-dimensional molded mask has the following structural features: In the edge region of the outer mask body, the edge contour of the intermediate support layer is smaller than the edge contours of the outer layer and the inner layer, so that the edge of the outer layer and the edge of the inner layer are in direct contact and sealed by adhesive. In a specific implementation, the edge contour of the intermediate support layer is 1-2 mm smaller than the edge contours of the outer layer and the inner layer.
[0032] Understandably, in the edge area of the outer mask body, because the edge contour dimensions of the outer and inner layers are larger than the intermediate support layer, the outer and inner layers are in direct contact at the outermost edge area of the mask body and are bonded together with adhesive to form an edge sealing layer covering the edge of the intermediate support layer. This edge sealing layer is directly laminated from the outer and inner fabrics, is relatively thin, and has smooth edges, requiring no additional sewing or edge binding. Meanwhile, the edge contour of the intermediate support layer (sandwich fabric) is small and does not extend to the outermost edge of the mask body, but its edge mesh is open after cutting. During the hot-pressing lamination step, the molten adhesive flows towards the edge area under pressure, and some of the adhesive penetrates into the exposed mesh of the sandwich fabric edge, wrapping and fixing the fiber cross-section.
[0033] The adhesive, which penetrates into the mesh openings at the edges of the sandwich fabric, cures upon cooling to form an anti-yellowing encapsulation layer. This encapsulation layer is not applied to the surface of the mask, but rather fills the mesh openings at the edges of the sandwich fabric, encapsulating each fiber cross-section within the adhesive matrix.
[0034] See further Figure 3 In a specific implementation, one or more first openings are formed on the surface layer, and one or more second openings are formed on the inner layer; the intermediate support layer has a continuous structure in the areas corresponding to the first and second openings. At the cut edges of the first and / or second openings, the adhesive is continuously distributed and penetrates into the intermediate support layer, forming an anti-yellowing encapsulation layer that extends continuously along the cut edges of the first and / or second openings after curing.
[0035] This invention achieves comprehensive anti-yellowing encapsulation of the entire edge of the mask by continuously distributing and penetrating the adhesive into the intermediate support layer at all cut edges of the mask—including the outer peripheral edge and the opening edges on the surface layer and / or inner layer. After cooling and curing, an anti-yellowing encapsulation layer is formed that extends continuously along each cut edge, so that the fiber cross-sections at all cut edges are wrapped and protected, thus achieving all-round anti-yellowing encapsulation of the entire edge of the mask.
[0036] In practice, the width of the anti-yellowing encapsulation layer is 3-5mm. If the width of the anti-yellowing encapsulation layer is less than 3mm, some fiber sections may not be fully wrapped, affecting the anti-yellowing effect and feel; if it is greater than 5mm, it may excessively occupy the breathable area in the middle, adversely affecting the overall breathability.
[0037] In a specific embodiment, the adhesive of the present invention comprises, by weight, 100 parts of aliphatic PUR prepolymer, 0.3 to 1.5 parts of antioxidant system, 0.5 to 2.0 parts of ultraviolet absorber, and 0.5 to 3.0 parts of physical pore-forming agent.
[0038] In a specific embodiment, the aliphatic PUR prepolymer is a moisture-curing reactive polyurethane hot melt adhesive prepolymer, and its isocyanate raw material is selected from one or more of isophorone diisocyanate (IPDI) and hexamethylene diisocyanate (HDI). Compared with conventional aromatic isocyanates (such as MDI and TDI), aliphatic isocyanates do not contain benzene rings in their molecular structure, and they are less prone to yellowing under ultraviolet light irradiation, thus giving the adhesive excellent light aging resistance from the source. Specifically, it can be selected from: IPDI type PUR prepolymer, HDI type PUR prepolymer, or IPDI and HDI mixed type PUR prepolymer, with an NCO content preferably of 1.5%~3.5% and a melt viscosity (120℃) preferably of 3000~8000 mPa·s to ensure good coating performance and hot pressing fluidity.
[0039] In a specific embodiment, the antioxidant system is composed of hindered phenolic antioxidants and phosphite antioxidants in a mass ratio of 6:4 to 7:3. Wherein: Hindered phenolic antioxidants: selected from one or more of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (such as Irganox 1010) and octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (such as Irganox 1076). Used to capture free radicals generated during the thermo-oxidative degradation of polymers, interrupting the chain oxidation reaction.
[0040] Phosphite antioxidants: selected from one or more of tris(2,4-di-tert-butylphenyl) phosphites (such as Irgafos 168) and pentaerythritol diphosphites (such as antioxidant 626). They are used to decompose hydroperoxides generated during oxidation, converting them into stable alcohol compounds and preventing further formation of free radicals.
[0041] In a specific embodiment, hindered phenols capture free radicals, and phosphites decompose hydroperoxides. Both block the oxidation chain reaction at different stages, resulting in a superior antioxidant effect compared to a single component. In this embodiment, the total amount of the antioxidant system added is 0.3 to 1.5 parts, specifically 0.3 parts, 0.8 parts, 1.2 parts, 1.5 parts, etc.; the mass ratio of hindered phenols to phosphites can be specifically 6:4, 6.5:3.5, or 7:3.
[0042] In a specific embodiment, the ultraviolet absorber is selected from one or more of benzotriazole ultraviolet absorbers and triazine ultraviolet absorbers. Specifically, it can be selected from: 2-(2H-benzotriazole-2-yl)-4,6-di-tert-pentylphenol (e.g., Tinuvin 328), 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-hexyloxyphenol (e.g., Tinuvin 1577), 2-hydroxy-4-n-octyloxybenzophenone (UV-531), etc. The ultraviolet absorber can selectively absorb the energy of the ultraviolet light band (290-400nm) and convert it into heat energy for release, avoiding direct action of ultraviolet light on the polymer molecular chain to induce photo-oxidation reaction. In this embodiment, the amount of ultraviolet absorber added is 0.5~2.0 parts, specifically 0.5 parts, 1.0 parts, 1.5 parts, 2.0 parts, etc.
[0043] Understandably, when hindered phenolic antioxidants are used in combination with phosphite antioxidants, the phenoxy radicals generated after the hindered phenols capture free radicals can be regenerated by the phosphites, thus extending the effective lifespan of the hindered phenols. Simultaneously, the alcohol compounds generated from the decomposition of hydroperoxides by phosphites do not participate in free radical chain reactions, avoiding secondary initiation. Ultraviolet absorbers convert ultraviolet light energy into heat energy, reducing the generation rate of photo-initiated free radicals and thus lessening the burden on the antioxidant system. Therefore, at the same total addition amount, the antioxidant efficiency of the combination system with the ultraviolet absorber is significantly higher than the sum of the individual components.
[0044] In a specific embodiment, the physical pore-forming agent is micron-sized thermally expandable microspheres. The thermally expandable microspheres consist of a thermoplastic polymer shell and a low-boiling-point hydrocarbon foaming agent encapsulated within the shell. The shell material is selected from one or more of acrylonitrile-acrylate copolymer and vinylidene chloride-acrylonitrile copolymer. The microsphere particle size is preferably 10-30 μm, the initial expansion temperature is preferably 80-100℃, and the maximum expansion temperature is preferably 120-150℃. During hot pressing, when the temperature rises above the initial expansion temperature of the microspheres, the shell softens, the internal foaming agent vaporizes, generating pressure, and the microspheres expand in volume to form hollow micropores; the micropore structure is maintained after cooling. The micropores are distributed within the adhesive layer, forming additional air-permeable channels, further improving the breathability of the mask. In this embodiment, the amount of the physical pore-forming agent added is 0.5-3.0 parts, specifically 0.5 parts, 1.0 parts, 2.0 parts, 3.0 parts, etc.
[0045] To further enhance the light stabilization effect, the adhesive may also contain a hindered amine light stabilizer (HALS). The hindered amine light stabilizer is selected from one or more of the following: bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacic acid (e.g., Tinuvin 292), and polymers of succinic acid and (4-hydroxy-2,2,6,6-tetramethyl-1-piperidinol) (e.g., Tinuvin 622). It can capture free radicals generated during photo-oxidation, forming a synergistic effect with ultraviolet absorbers: the ultraviolet absorbers reduce ultraviolet light incidence, and the hindered amine light stabilizers capture the generated free radicals; the combination of the two significantly improves the fabric's resistance to photoaging. In this embodiment, the amount of hindered amine light stabilizer added is 0.1~0.5 parts, specifically 0.1 parts, 0.3 parts, 0.5 parts, etc.
[0046] Understandably, adhesives may also contain small amounts of functional additives as needed, such as: wetting and leveling agents: 0.1-0.3 parts, selected from polyether-modified polysiloxanes, used to improve the spreadability of the adhesive on the substrate surface; defoamers: 0.05-0.2 parts, selected from silicone-free polymer defoamers, used to prevent the formation of bubbles during coating; tackifying resins: 1-5 parts, selected from rosin resins, terpene resins, etc., used to adjust initial tack and open time. The addition of the above additives must ensure compatibility with the PUR system and not affect the anti-yellowing function.
[0047] This invention also provides a method for preparing the above-mentioned anti-yellowing, highly breathable, three-dimensional molded mask, comprising the following steps: S1. Preparation of the adhesive, specifically including the following steps: (1) Matrix heating: Add 100 parts of aliphatic PUR prepolymer to a sealed reactor equipped with a stirrer and heating device, and heat to 100~120℃ to make the prepolymer completely melt and flow in a uniform state. During the heating process, maintain nitrogen protection to prevent the prepolymer from reacting with moisture in the air.
[0048] (2) Addition of antioxidant system and ultraviolet absorber: Maintain the temperature at 100~120℃, and slowly add 0.3~1.5 parts of antioxidant system and 0.5~2.0 parts of ultraviolet absorber while stirring. After the addition is complete, stir at 200~400 rpm for 20~30 minutes until the additives are completely dissolved or uniformly dispersed in the prepolymer. If the formulation contains hindered amine light stabilizer (0.1~0.5 parts), add it together in this step.
[0049] (3) Cooling and addition of physical porogen: Cool the system temperature to 70-80℃ (below the initial expansion temperature of the thermally expanding microspheres), and slowly add 0.5-3.0 parts of physical porogen while stirring at low speed (100-150 rpm). Maintain this temperature and continue stirring for 10-15 minutes to ensure uniform dispersion of the microspheres. Care should be taken to control the stirring speed and temperature to avoid premature expansion or rupture of the microspheres.
[0050] (4) Vacuum degassing: Evacuate the system to -0.08~-0.1MPa and maintain for 10~15 minutes to remove air bubbles mixed in during stirring. After degassing is complete, restore normal pressure to obtain a uniform adhesive.
[0051] (5) Discharge and sealing: While the prepared adhesive is still hot (70~80℃), discharge it into a sealed container and store it in a sealed container to prevent contact with moisture in the air. Before use, it needs to be reheated and melted at 70~80℃ (below the initial expansion temperature of the thermal expansion microspheres) and coated while maintaining this temperature.
[0052] S0. Preparation of cut pieces.
[0053] In a specific embodiment, before the partition coating in step S2, the outer fabric, sandwich fabric and inner fabric are cut separately to form cut pieces with specific contours and opening structures.
[0054] See Figure 3 These are schematic diagrams of the fabric shapes of the outer layer, inner layer, and middle support layer, respectively, cut to size.
[0055] Outer Layer Piece: After being cut, the outer layer fabric has an overall shield-shaped silhouette that tapers at the bottom and widens at the top, conforming to the curve of the cheekbone to the jawline of the human face. A large opening is located in the lower central area of the outer layer piece, corresponding to the wearer's mouth and nose breathing area. This opening design ensures that after molding, the mask forms an open breathing chamber corresponding to the mouth and nose area, reducing the obstruction of airflow by the outer fabric and improving breathability. Simultaneously, the edge of the opening is bonded to the intermediate support layer and inner layer during subsequent molding, forming an integrated three-dimensional structure.
[0056] Inner layer: After cutting, the inner layer fabric has a shape that is basically the same as the outer layer, maintaining a shield-shaped overall outline to ensure alignment with the edges of the outer layer. Unlike the outer layer, the inner layer uses a symmetrical double-hole layout—two longitudinally extending teardrop-shaped holes are arranged on both sides of the longitudinal center line of the inner layer, forming a "dual-channel" structure for the nose area. This double-hole design allows the inner layer to form an independent support frame on both sides of the corresponding bridge of the nose after molding. On the one hand, it provides a separate fitting space for the left and right sides of the nose; on the other hand, the connecting ribs between the double holes enhance the structural strength of the middle of the mask, preventing it from collapsing when worn.
[0057] Middle Support Layer Piece: After the sandwich fabric is cut, its bottom contour extends in a wave-like pattern following the curve of the jawline to increase the contact area between the lower edge of the mask and the jawline, improving wearing stability. The top of the middle support layer piece follows the cheek and eye area in a symmetrical U-shape, with a V-shaped notch precisely positioned in the center. This notch, after molding, corresponds to the highest point of the nose bridge. The V-shaped notch creates space for the sandwich fabric in the nose bridge area, preventing excessive accumulation of the sandwich fabric and the resulting pressure. At the same time, the sandwich fabric on both sides of the notch naturally forms a three-dimensional skeleton that wraps around the sides of the nose bridge and covers the cheeks after molding, enhancing the fit between the mask and the nose and face.
[0058] The three layers of fabric pieces described above meet the following dimensional requirements: the edge contours of the outer and inner layers are basically the same, while the edge dimensions of the sandwich fabric piece are smaller than those of the outer and inner layers, creating a 1-2mm size difference. This size difference design allows the outer and inner layers to directly contact and adhere to each other in the edge area during the subsequent hot-pressing process, forming an edge-sealing structure that covers the edges of the sandwich fabric.
[0059] The large opening in the outer layer provides the main breathing channel, while the double holes in the inner layer form a support framework for the nasal area. The V-shaped notch and wavy bottom of the middle support layer allow for nose bridge clearance and a snug fit under the chin. After subsequent heat-pressing and bonding, the three-layer structure forms an integrated mask structure with gradient breathable channels and a three-dimensional support framework. The direct bonding of the outer and inner layers at the edges, combined with the smaller edge size of the middle support layer, constitutes an edge-sealing system that eliminates the need for additional edge-binding.
[0060] S2, Partial Coating: Applying adhesive between the surface fabric and the sandwich fabric, and between the sandwich fabric and the inner fabric; wherein, continuous coating is applied to the cut edge areas of the surface fabric, sandwich fabric, and / or inner fabric; the adhesive is applied in a dotted or grid pattern to the non-cut edge areas of the surface fabric, sandwich fabric, and / or inner fabric.
[0061] In practice, continuous coating is applied to the outer periphery, the opening edge of the surface layer, and the opening edge of the inner layer of the mask, while dotted or grid-like coating is applied to the middle area of the mask.
[0062] The coating width on the outer edge of the mask is 4-6mm, and the coating amount is controlled at 15-25g / m². 2 This ensures that sufficient adhesive penetrates into the mesh edges of the sandwich fabric to form an encapsulation layer during the subsequent hot pressing process.
[0063] Because the outer layer fabric has a large opening in the corresponding breathing area of the mouth and nose, the edge of this opening forms the boundary between the inner wall of the mask and the outside after molding. Therefore, a continuous coating is applied between the outer layer fabric and the sandwich fabric, corresponding to the circumferential area of the opening edge of the outer layer, with a coating width of 3-5mm. This allows the adhesive to cover the fiber cross-section of the opening edge, preventing yellowing or roughness in this area due to cutting exposure.
[0064] The inner fabric features a symmetrical double-hole layout, with two longitudinally extending teardrop-shaped holes positioned on either side of the longitudinal center line of the cut piece. Between the inner fabric and the sandwich fabric, a continuous coating is applied to the circumferential area corresponding to the edges of each hole opening in the inner layer. The coating width is 3-5 mm, ensuring the adhesive covers the fiber cross-sections at the inner layer opening edges, thus guaranteeing that the supporting frame edges on both sides of the nose bridge also receive anti-yellowing protection.
[0065] In addition to the aforementioned edge areas and opening edge areas, dotted or grid-like coatings are applied to the middle area of the mask body (i.e., the area between the outer and inner layers excluding the edges and openings). The coating coverage accounts for 20% to 35% (e.g., 20%, 25%, 30%, 35%) of the total single-sided fabric area in the middle area, and the coating amount per side is controlled at 5 g / m². 2 ~12g / m 2 It retains more than 65% of the original fiber porosity and uses low-coverage coating to ensure the basic bonding strength between the surface layer, the middle support layer and the inner layer while maximizing the breathability of the sandwich fabric.
[0066] It should be noted that the continuous coating design at the opening edges of the outer and inner layers, together with the continuous coating at the outer perimeter of the mask, constitutes a complete edge sealing system. The opening edges, as the boundary connecting the mask structure to the outside world, are also areas where fiber cross-sections are concentratedly exposed. Through continuous adhesive coating and subsequent hot-pressing penetration, these cross-sections are encapsulated in the adhesive, achieving the same anti-yellowing protection and improved feel as the outer perimeter of the mask. Simultaneously, because the continuous coating area at the opening edges is relatively narrow (3-5mm) and distributed only along the circumference of the opening, it does not significantly affect the overall breathable area of the mask.
[0067] S3. First Hot-Pressure Lamination: The coated surface fabric, sandwich fabric, and inner fabric are stacked and placed in a positioning mold for the first hot-pressing, causing the adhesive to melt and flow. The edge dimensions of the sandwich fabric are smaller than those of the surface and inner layers. During the hot-pressing process, the surface and inner layers directly contact and adhere at their edges to form an edge sealing layer. Simultaneously, the molten adhesive penetrates into the exposed mesh of the sandwich fabric edges, encapsulating the fiber cross-sections and forming an anti-yellowing encapsulation layer upon cooling. In the middle region, the adhesive bonds the surface fabric, sandwich fabric, and inner fabric together.
[0068] See Figure 4 This is a photograph of the outer surface after the first molding in the preparation method of the anti-yellowing, high-breathability, three-dimensional molded mask provided in an embodiment of the present invention. Specifically, the temperature of the first hot pressing is 165-175℃, and the time is 50-60 seconds, causing the adhesive to melt and flow. During the hot pressing process, the outer layer and the inner layer are directly bonded together at the edge area to form a sealing layer. Simultaneously, the molten adhesive penetrates into the exposed mesh of the sandwich fabric edge, encapsulating the fiber cross-sections. After cooling, an anti-yellowing encapsulation layer is formed. In the middle area, the adhesive bonds the various fabric layers together. This embodiment simultaneously achieves three functions—edge sealing, fiber cross-section encapsulation, and middle area bonding—through the first hot pressing, solving the problem that traditional processes require multiple steps to handle the edges and bonding separately.
[0069] S4. Second molding and shaping: The composite sheet obtained in step S3 is placed in a three-dimensional mask mold for a second hot pressing to form the outer mask body with a three-dimensional shape.
[0070] See Figure 5 This is a photograph of the outer surface after the second molding process in the preparation method of the anti-yellowing, highly breathable, three-dimensional molded mask provided in an embodiment of the present invention. Specifically, the temperature of the second hot pressing is 165-175℃, and the time is 50-60 seconds. The second hot pressing imparts the final three-dimensional shape to the mask, solving the problem that flat materials cannot conform to facial curves.
[0071] Understandably, since the adhesive contains a physical pore-forming agent—micron-sized thermally expanding microspheres—the microspheres expand under heat during the hot pressing process in step S3 or S4 to form micropores, allowing the adhesive layer to obtain its own air-permeable channels, thereby further improving the air permeability of the final product.
[0072] In another embodiment, the preparation method of the present invention further includes the preparation and assembly steps of the inner bean-shaped pad.
[0073] Step S5: Preparation of inner bean pad: After the inner fabric is combined with the sponge, it is placed in the bean mold for molding and shaping to form an inner bean pad with a three-dimensional raised structure.
[0074] In this embodiment, the inner layer of the padding is composed of an inner fabric layer and a sponge layer. Wherein: Inner layer fabric: Select skin-friendly fabrics that come into contact with the skin, such as cotton knitted fabric, modal fabric, or ultra-fine denier polyester knitted fabric, with a preferred weight of 80~120g / m². 2 To ensure a soft touch and moisture-wicking breathability.
[0075] Sponge layer: Polyurethane soft sponge is selected, with a preferred density of 20~35 kg / m³. 3 The thickness is preferably 2~5mm. During the molding process, the sponge layer is heated and compressed to form a permanent three-dimensional raised structure, providing cushioning support.
[0076] The adhesive can be the adhesive of this invention, a commercially available environmentally friendly PUR hot melt adhesive, or a water-based polyurethane adhesive, with the coating amount controlled at 15~25g / m². 2 This ensures composite strength while maintaining a soft feel.
[0077] See Figure 6 This is a photograph of a bean-shaped inner lining provided in another embodiment of the present invention. In this embodiment, based on the contact area between the inner surface of the mask and the bridge of the nose and cheeks when worn, the composite material is cut into padding pieces of a specific shape, such as an oval, crescent, or "、" shape, with a length of 15-30mm and a width of 5-15mm, to cover the area from below the cheekbones to the cheeks. The edges of the padding pieces can be designed as smooth curves to avoid lifting or indentation after fitting.
[0078] The cut padding pieces are placed in a specially made bean mold for molding and shaping, forming an inner bean-shaped pad with a three-dimensional raised structure. The molding process parameters are as follows: Mold temperature: upper mold 180~190℃, lower mold 180~190℃ (preferably 185℃ in this embodiment); molding time: 180~200 seconds (preferably 194 seconds in this embodiment); molding pressure: 0.3~0.5MPa.
[0079] Under high temperature and pressure, the sponge layer undergoes irreversible plastic deformation, forming a three-dimensional protrusion structure corresponding to the mold cavity. The protrusion height is preferably 2~4mm. This three-dimensional protrusion structure forms multiple points of contact with the facial skin when worn, providing cushioning support and reducing the contact area between the skin and the padding, which is conducive to air circulation and avoids local stuffiness.
[0080] After molding, remove the liner from the mold, allow it to cool and set naturally, and set for later use.
[0081] Step S6, Assembly: Attach the inner bean pad to the preset position of the inner fabric and perform a third hot pressing fixation at a temperature of 155-165℃ for 45-55 seconds.
[0082] In specific implementation, see Figure 7 Place the outer mask body obtained in step S4 flat on the assembly fixture with the inner surface facing upwards. Based on the three-dimensional contour of the inner surface of the mask body, mark the positions corresponding to the bridge of the nose and cheeks of the human body when wearing it, or determine the position of the padding by using positioning pins.
[0083] The prepared inner layer of pimple padding is placed at a predetermined position on the inner surface of the outer layer of the mask body, with the three-dimensional raised surface of the pad facing the inner surface of the mask body (i.e., the raised surface is in contact with the mask body), or the raised surface can face the skin side as required by the design. In this embodiment, it is preferred that the raised surface face the skin side so as to directly exert a cushioning effect.
[0084] The assembled assembly is placed in a fitting mold for a third hot-pressing fixation. The process parameters are as follows: Mold temperature: 155~165℃ (preferably 160℃ in this embodiment); hot pressing time: 45~55 seconds (preferably 50 seconds in this embodiment); hot pressing pressure: 0.2~0.4MPa.
[0085] During the hot pressing process, the adhesive on the inner surface of the outer mask body (or the pre-coated film on the back of the pad) melts under heat, bonding and fixing the pad to the mask body. After hot pressing is completed, the mask is cooled and demolded to obtain a complete semi-finished composite mask.
[0086] Finally, the assembled semi-finished mask is placed in a special die for cutting and trimming to remove excess material and ensure a neat and consistent overall shape. After trimming, an appearance inspection is conducted, and if it passes the inspection, it becomes the finished product.
[0087] Understandably, the outer layer of the mask provides an overall three-dimensional shape and highly breathable support, while the inner layer of padded liner provides localized cushioning in high-pressure areas such as the bridge of the nose and cheeks. After the two layers are bonded together through a third heat-pressing process, tiny gaps are formed between the raised structure of the liner and the inner surface of the main body, further increasing localized airflow and preventing stuffiness caused by prolonged wear.
[0088] Performance verification To verify the beneficial effects of the technical solution of the present invention, the following performance tests were conducted.
[0089] (a) Test Sample Example 1: A high-breathability, anti-yellowing, three-dimensional molded mask prepared according to a specific embodiment of the present invention includes an inner layer of bean-shaped padding. The adhesive formulation is as follows: 100 parts of aliphatic PUR prepolymer (IPDI type), 1.0 part of an antioxidant system (Irganox 1010:Irgafos 168 = 7:3), 1.5 parts of an ultraviolet absorber (Tinuvin 328), and 2.0 parts of a physical pore-forming agent (thermally expanding microspheres, initial expansion temperature 85℃). Partial coating: continuous coating width of 5mm at the edges, dotted coating coverage of 25% in the central area, coating amount of 8g / m². 2 The three-layer cut pieces have a size difference of 1.5mm, and the anti-yellowing encapsulation layer is 4mm wide.
[0090] Example 2: Basically the same as Example 1, except that the amount of antioxidant system used is 0.5 parts (hindered phenol: phosphite = 6:4).
[0091] Example 3: Basically the same as Example 1, except that the amount of ultraviolet absorber used is 1.0 part.
[0092] Example 4: Basically the same as Example 1, except that the amount of physical porogen used is 1.0 part.
[0093] Example 5: Basically the same as Example 1, except that the coverage of the dotted coating in the middle area is 30%, and the coating amount is 10g / m². 2 .
[0094] Comparative Example 1 (Matrix Comparison): It is basically the same as Example 1, except that the aliphatic PUR prepolymer is replaced with an equal amount of aromatic PUR prepolymer (MDI type), while the other components and processes remain unchanged.
[0095] Comparative Example 2 (without antioxidant system): It is basically the same as Example 1, except that no antioxidant system is added to the adhesive, and it only contains 1.5 parts of ultraviolet absorber.
[0096] Comparative Example 3 (UV absorber missing): It is basically the same as Example 1, except that no UV absorber is added to the adhesive, and it only contains 1.0 part of antioxidant system.
[0097] Comparative Example 4 (lacking both antioxidants and UV absorbers): basically the same as Example 1, except that no antioxidant system and UV absorber are added to the adhesive.
[0098] Comparative Example 5 (lacking physical porogen): basically the same as Example 1, except that no physical porogen is added to the adhesive.
[0099] Comparative Example 6 (Edge Structure Comparison): It is basically the same as Example 1, except that the edge dimensions of the three-layer cut pieces are consistent (no inward shrinkage), and the edge area is still continuously coated but there is no direct bonding structure between the surface layer and the inner layer.
[0100] Comparative Example 7 (Coating Method Comparison): Basically the same as Example 1, except that the middle area is fully coated (coating coverage 100%), and the coating amount is 8 g / m². 2 .
[0101] Comparative Example 8 (without inner bean pad): basically the same as Example 1, except that it does not include the inner bean pad.
[0102] Comparative Example 9 (no porogen and full coverage coating): basically the same as Example 1, except that no physical porogen is added to the adhesive and the middle area is fully coated (100% coverage), with a coating amount of 8 g / m². 2 .
[0103] (II) Test Methods and Results 1. Yellowing resistance test Test method: Refer to GB / T 16585-1996 "Artificial Weathering (Fluorescent Ultraviolet Lamp) Test Method for Vulcanized Rubber". Place the sample in an ultraviolet aging test chamber, using a UVA-340 lamp with an irradiance of 0.76 W / m². 2 The blackboard temperature was 60℃, and the cycle of 8 hours of light exposure followed by 4 hours of condensation was repeated for 100 hours. The yellowing index ΔYI of the samples before and after the test was measured using a colorimeter. A smaller ΔYI value indicates better yellowing resistance. Three parallel samples were tested for each sample, and the average value was taken. The results are shown in Table 1.
[0104] Table 1 Results of yellowing resistance test Regarding the mask of Example 1, this experiment also tested the yellowing resistance in the following three different regions, and the results are as follows: Area A: Mouth and nose exposed area (directly exposed area of the sandwich fabric) ΔYI=2.1; Region B: The central area covered by adhesive (dot-coated area) ΔYI=1.8; Region C: Edge encapsulation area (continuous adhesive layer) ΔYI=1.5.
[0105] It can be seen that the adhesive of Example 1 uses aliphatic PUR as the matrix, and ΔYI (1.8) is much better than that of aromatic PUR (10.3) in Comparative Example 1, which proves that aliphatic isocyanate significantly improves the anti-yellowing property at the matrix level. At the same time, although the mouth and nose exposed area of the mask (the area directly exposed by the sandwich fabric) is not coated with adhesive, it still has anti-yellowing properties. This may be because during the hot pressing process, the small molecule antioxidants and ultraviolet absorbers in the adhesive diffuse or migrate, thus having a certain anti-yellowing property.
[0106] Comparative Example 2 lacked an antioxidant system (only UV absorber was added), ΔYI=5.4; Comparative Example 3 lacked a UV absorber (only antioxidant system was added), ΔYI=5.9; Comparative Example 4 lacked both an antioxidant system and a UV absorber, ΔYI=7.2. This indicates that the combination of antioxidant system and UV absorber in the adhesive has a synergistic effect on yellowing resistance, and a single component cannot achieve comprehensive protection.
[0107] 2. Air permeability test Test method: Refer to GB / T 5453-1997 "Textiles - Determination of air permeability of fabrics", the test area is 20cm². 2 The pressure drop was 100 Pa. The average value of the test was taken 5 times for the middle area of the mask body of each sample. The results are shown in Table 2.
[0108] Table 2. Results of air permeability test Test results show that, compared with Comparative Example 5, Example 1 with added physical pore-forming agent (air permeability 385 mm / s) is 26% more permeable than without pore-forming agent (305 mm / s), proving that the micropores formed by thermally expanded microspheres effectively increase the air permeability channels of the adhesive layer itself.
[0109] The adhesive of Comparative Example 7 was a full-coverage coating, and even with the micropores formed by thermally expanded microspheres, the air permeability was poor. The adhesive of Comparative Example 9 did not contain pore-forming agents and was a full-coverage coating, with an air permeability of only 220 mm / s. This proves that the present invention uses a partitioned coating to retain the original pores of the sandwich fabric, which can greatly improve the air permeability.
[0110] In fact, physical pore-forming agents create micron-sized closed or semi-open pore structures within the adhesive layer, providing the adhesive layer with its own air-permeable channels. The zoned coating preserves the original mesh of the sandwich fabric in the middle region, forming a dual-scale air-permeable network of 'fabric macropores + adhesive layer micropores'. Therefore, even if the adhesive is distributed in a dotted pattern in the middle region, the micropores within the adhesive layer at the covered points can still provide localized air permeability compensation, resulting in an overall air permeability superior to a single path relying solely on fabric pores or adhesive layer micropores.
[0111] 3. Subjective evaluation of edge tactile sensation Test method: Twenty subjects were selected and blindedly wore masks of Example 1 and Comparative Example 1 for 10 minutes each. The itching sensation at the contact area between the mask edge and the cheek was evaluated, and the scoring standard was 1-5 points (1 point: obvious itching; 5 points: no itching). The average score of each sample was taken, and the results are shown in Table 3.
[0112] Table 3 Tactile Evaluation Results Test results show that the edge feel score of Example 1 (4.8) is significantly higher than that of Comparative Example 6 (2.3), indicating that the edge sealing layer formed by the direct bonding of the top and inner layers effectively eliminates the itching sensation caused by the fiber cross-section. Comparative Example 7 (full coating in the middle) scored 4.7, indicating that full coating has no significant effect on edge feel, and edge feel is mainly determined by the edge structure.
[0113] 4. Peel strength test Test method: Refer to GB / T 2790-1995 "Test method for 180° peel strength of adhesives, flexible materials to rigid materials", test the peel strength of the adhesive layer between the outer layer and the middle support layer, and between the middle support layer and the inner layer. Each sample is tested 3 times and the average value is taken. The results are shown in Table 4.
[0114] Table 4. Peel strength results. Test results show that the peel strength of each sample is above 3.0 N / cm, with no significant difference, proving that the addition of antioxidant system, ultraviolet absorber, physical pore-forming agent and partitioned coating method did not have an adverse effect on the adhesive performance.
[0115] 5. Cushioning performance test of the inner layer of pimple padding Test method: A compression tester was used to apply 5N of pressure to the bridge of the nose and measure the compression displacement (mm). The larger the displacement, the better the cushioning performance. Each sample was tested 5 times and the average value was taken. The results are shown in Table 5.
[0116] Table 5. Buffer performance results. Test results show that the compression displacement of the sample with inner pimple pad (2.8 mm) is significantly greater than that of the sample without pad (0.9 mm), indicating that the inner pimple pad provides good cushioning support and can effectively disperse the pressure on the bridge of the nose.
[0117] The test results above indicate that the aliphatic PUR prepolymer, antioxidant system, UV absorber, physical pore-forming agent, partitioned coating method, and inner layer pimple padding in the adhesive all have a positive impact on product performance. The synergistic effect of these features makes the mask of this invention superior to the comparative example in terms of yellowing resistance, breathability, edge comfort, adhesive strength, and localized cushioning.
[0118] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.
[0119] The above description describes specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.
Claims
1. A three-dimensional molded mask with anti-yellowing and high breathability, characterized in that, include: The outer mask body includes a surface layer, a middle support layer, and an inner layer; The intermediate support layer has a mesh structure; The surface layer and the intermediate support layer, as well as the intermediate support layer and the inner layer, are bonded together with adhesive and then molded together. The adhesive, by weight, comprises: 100 parts aliphatic PUR prepolymer, 0.3-1.5 parts antioxidant system, 0.5-2.0 parts ultraviolet absorber, and 0.5-3.0 parts physical pore-forming agent; The edge contours of the intermediate support layer are all smaller than the edge contours of the surface layer and the inner layer, so that the edge of the surface layer and the edge of the inner layer are in direct contact and are sealed by adhesive. Meanwhile, the adhesive penetrates into the cut edge of the intermediate support layer, wraps and fixes the cut edge of the intermediate support layer, and after curing, forms an anti-yellowing encapsulation layer that extends continuously along the cut edge of the intermediate support layer.
2. The anti-yellowing, highly breathable, three-dimensional molded mask according to claim 1, characterized in that, The surface layer has one or more first openings, and the inner layer has one or more second openings; the adhesive penetrates the intermediate support layer at the cut edges of each of the first openings and / or each of the second openings, and after curing, forms an anti-yellowing encapsulation layer that extends continuously along the cut edges of the first openings and / or each of the second openings.
3. The anti-yellowing, highly breathable, three-dimensional molded mask according to claim 1, characterized in that, The edge contour of the intermediate support layer is 1-2 mm smaller than the edge contours of the surface layer and the inner layer.
4. The anti-yellowing, highly breathable, three-dimensional molded mask according to claim 1, characterized in that, The physical porogen is a micron-sized thermally expandable microsphere; after curing, the adhesive has micropores inside formed by the thermal expansion or decomposition of the physical porogen.
5. The anti-yellowing, highly breathable, three-dimensional molded mask according to claim 1, characterized in that, The adhesive is distributed in a dotted or grid-like pattern in the non-cut edge areas of the surface layer, intermediate support layer, and / or inner layer.
6. The anti-yellowing, high-breathability, three-dimensional molded mask according to claim 1 or 2, characterized in that, The width of the anti-yellowing encapsulation layer is 3-5mm.
7. The anti-yellowing, highly breathable, three-dimensional molded mask according to claim 1, characterized in that, It also includes an inner beaded pad, which is attached to the inner surface of the outer mask body and is located at the corresponding position of the human nose bridge and / or cheek when worn.
8. A method for preparing a three-dimensional molded mask with anti-yellowing and high breathability, characterized in that, Includes the following steps: S1. Preparation of adhesive: By weight, heat 100 parts of aliphatic PUR prepolymer to a molten state, add 0.3~1.5 parts of antioxidant system, 0.5~2.0 parts of ultraviolet absorber, and 0.5~3.0 parts of physical pore-forming agent and mix evenly; S2. Coating: The prepared adhesive is coated on the inner surface of the surface fabric, the two surfaces of the middle support layer fabric, and the inner surface of the inner fabric. S3. Hot-press lamination: The coated surface fabric, the middle support layer fabric, and the inner fabric are stacked in sequence and placed in a positioning mold for the first hot pressing, so that the surface fabric, the middle support layer fabric, and the inner fabric are bonded together. S4. Molding and shaping: The composite sheet obtained in step S3 is placed in a three-dimensional mask mold for a second hot pressing to form the outer mask body with a three-dimensional shape.
9. The preparation method according to claim 8, characterized in that, In step S2, the adhesive is continuously applied to the cut edge areas of the surface fabric, the intermediate support layer fabric, and / or the inner fabric; the adhesive is applied in a dotted or grid pattern to the non-cut edge areas of the surface fabric, the intermediate support layer fabric, and / or the inner fabric, wherein the coverage of the dotted or grid pattern coating accounts for 20% to 35% of the total area of a single side of the fabric.
10. The preparation method according to claim 9, characterized in that, Before the coating step S2, a fabric preparation step is also included: cutting the outer layer fabric, the middle support layer fabric, and the inner layer fabric according to the design pattern, so that the edge contour of the middle support layer fabric is smaller than the edge contour of the outer layer and the edge contour of the inner layer.
11. The preparation method according to claim 8, characterized in that, The temperature of the first hot pressing in step S3 is 165-175℃, and the time is 50-60 seconds; the temperature of the second hot pressing in step S4 is 165-175℃, and the time is 50-60 seconds.
12. The preparation method according to claim 8, characterized in that, It also includes step S5, preparation of the inner bean pad: after the inner fabric is combined with the sponge, it is placed in the bean mold for molding and shaping to form an inner bean pad with a three-dimensional raised structure. Step S6, Assembly: Attach the inner bean pad to the preset position of the inner fabric and perform a third hot pressing fixation at a temperature of 155-165℃ for 45-55 seconds.