Lightweight coated heat-shielding umbrella fabric and method of making same

Abstract

The application discloses a light coating heat-shielding umbrella cloth and a preparation method thereof, and belongs to the technical field of sunshade fabrics. The umbrella cloth comprises a reinforced base cloth with a surface density less than 35 g / m2 and a breaking strength greater than or equal to 200 N, a color-keeping reflective bottom layer and a modified aluminum silver paste reflective surface layer are sequentially coated on the base cloth, the overall surface density of the umbrella cloth is less than 65 g / m2, the heat-shielding rate is greater than 65%, and the light color fastness is greater than or equal to grade 4. The application reflects heat through the cooperation of the double-layer coating, realizes light weight while ensuring high heat-shielding rate, has good color-keeping property of the coating, has no light glare phenomenon, and simultaneously has excellent ultraviolet-proof and waterproof performances. The application further provides a preparation method of the umbrella cloth and a preparation method of the modified aluminum paste. The application overcomes the technical problem that light weight and high heat-shielding performance are difficult to be simultaneously achieved in the prior art, and is suitable for a light sunshade umbrella.

Description

Technical Field

[0001] This invention belongs to the field of sunshade fabrics, specifically relating to a lightweight, high heat-blocking coated umbrella fabric and its preparation method. Background Technology

[0002] Currently, the heat-blocking fabrics used for sun umbrellas on the market mainly use ordinary chemical fiber base fabric with a single sun-protective coating or a multi-layer thick coating structure, which generally have the following problems: 1. The surface density of conventional sun umbrella fabric is usually above 50g / ㎡. In order to achieve the heat-blocking effect, the existing technology usually applies a coating containing inorganic powder materials to the base fabric and uses a thickened coating or multi-layer composite structure to achieve the heat-blocking effect. As a result, the overall weight of the umbrella fabric generally exceeds 100g / ㎡, which is difficult to meet the needs of lightweight portable sun umbrellas.

[0003] 2. Some lightweight sunshade fabrics use only a single layer of titanium dioxide coating to reflect solar radiation heat. Although the weight is reduced, the heat shading rate is generally less than 40%.

[0004] 3. Some lightweight sunshade fabrics use only a single layer of aluminum powder coating to reflect solar radiation heat. Although the heat shading rate can be increased to 50% while reducing the weight, the heat shading rate still does not meet the requirement of 65%. In particular, this pure aluminum powder coating has strong light reflection, with a gloss level of 70-80 at 60° (tested by a Color Spectrum CS-300 gloss meter), which can easily cause glare and lead to visual fatigue.

[0005] 4. Although some existing technologies use double-layered sunshade fabrics, they are mostly ordinary functional layers with a coating weight of >50g / ㎡. They do not disclose the use of reinforced base fabric with a surface density of <35g / ㎡, nor do they achieve the technical effect of an overall umbrella fabric surface density of <65g / ㎡ and a heat shading rate of >65%.

[0006] The patent in question is titled: "A full-band sun protection and heat insulation ice gel umbrella and umbrella fabric", and the application number is CN202021213880.8. The technical solution of the patent mainly includes: (1) The fabric adopts a three-layer structure, with white yarn woven into the first and third fabric layers and dark black yarn woven into the second fabric layer. The yarn is 50D ultra-fine polyester fiber yarn and the fabric density is 320T; (2) The outer layer is coated with pearlescent iridescent glue (containing pearl powder) and the inner layer is coated with dark brown transparent glue; (3) The outer layer is also provided with a nano superhydrophobic coating. However, the patent has the following shortcomings: (1) The base fabric adopts a three-layer weaving structure (320T, 50D), and the overall surface density is relatively large, usually exceeding 50g / ㎡, which makes it impossible to achieve lightweighting; (2) The coating adopts a combination of "outer layer reflection + inner layer absorption", and its background technology also acknowledges that black glue "easily accumulates heat and fumes the space under the umbrella", and the heat absorption mechanism of the inner layer may cause a stuffy feeling under the umbrella; (3) The outer pearlescent iridescent glue has high gloss, which may cause glare problems, and no matting treatment is involved; (4) The reinforced base fabric with surface density <35g / ㎡ is not disclosed, and the technical effect of overall umbrella fabric surface density <65g / ㎡ and heat shielding rate >65% is not achieved; (5) The modification treatment of aluminum powder paste and anti-glare technology are not involved.

[0007] The patent in question is titled "An Umbrella Fabric and Its Manufacturing Method" and has the application number CN201710967281.1. The technical solution of this patent mainly uses a sunscreen coating containing nano-titanium dioxide to achieve the sunscreen function. However, this patent has the following shortcomings: (1) It only uses a single-layer coating structure, which is insufficient for reflecting infrared radiation heat. The heat shielding rate is generally lower than 40%, which is difficult to meet the high heat shielding requirements; (2) It does not use high reflective materials such as aluminum powder paste, which limits the heat shielding effect; (3) It does not involve a double-layer synergistic reflection structure, which cannot achieve full-band reflection; (4) It does not involve the matting modification treatment of aluminum powder paste, which has the problem of glare; (5) It does not disclose a reinforced base fabric with a surface density of <35g / ㎡, nor does it achieve the technical effect of an overall surface density of <65g / ㎡ and a heat shielding rate of >65% for the umbrella fabric.

[0008] The published patent is titled "A Multifunctional Fabric" and has the application number CN202220626621.0. The fabric in this patent includes a base fabric and multiple functional layers. However, this patent has the following shortcomings: (1) The total surface density of the coating is high, usually >50g / ㎡, resulting in a large overall weight of the umbrella fabric; (2) A reinforced base fabric with a surface density of <35g / ㎡ is not used; (3) The technical effect of an overall surface density of <65g / ㎡ and a heat-blocking rate of >65% is not achieved.

[0009] In summary, the existing technologies generally have the following defects: (1) Single-layer coating structures cannot take into account the reflection of visible light and infrared bands, resulting in low heat shielding rate (generally <50%); (2) Although double-layer or multi-layer structures can improve the heat shielding effect, the thick coating (total coating weight >50g / ㎡) results in an excessively large overall weight of the umbrella fabric (>100g / ㎡), making it difficult to meet the lightweight requirements; (3) Aluminum powder coatings have serious glare problems (60OGU≥70), affecting the comfort of use; (4) The existing technologies do not disclose a combination scheme of reinforced base fabric with surface density less than 35g / ㎡ and double-layer ultra-thin coating, and have not achieved the technical effect of overall surface density <65g / ㎡ and heat shielding rate >65%.

[0010] Therefore, existing sunshade umbrella fabrics struggle to simultaneously achieve lightweight, high heat-blocking efficiency, coating color retention, and anti-glare performance, resulting in a technical problem where lightweighting and high heat-blocking performance are mutually constrained. This invention is a solution proposed to address these technical problems. Summary of the Invention

[0011] Purpose of the invention: The purpose of this invention is to overcome the shortcomings of the existing technology and provide a lightweight coated heat-shielding umbrella fabric and its preparation method. It aims to solve the technical problem of the difficulty in achieving both lightweight umbrella fabric and high heat-shielding rate, while eliminating the glare phenomenon of aluminum powder coating, ensuring the color retention of coating, and realizing the integration of multiple functions such as heat shading, sun protection, and waterproofing.

[0012] Technical solution: In a first aspect, the present invention provides a lightweight coated heat-shielding umbrella fabric, comprising: a reinforced base fabric with a surface density of <35g / ㎡ and a tensile strength of ≥200N, wherein the reinforced base fabric is treated with silicone waterproofing. The reinforced base fabric is sequentially coated with a color-preserving reflective underlayer and a modified aluminum powder paste reflective surface layer; the color-preserving reflective underlayer contains rutile nano-titanium dioxide reflective particles; the modified aluminum powder paste reflective surface layer contains modified aluminum powder paste that has been matted and tinted, and the modified aluminum powder paste contains 2%-5% polyethylene wax and silica composite matting agent. The lightweight coated heat-shielding umbrella fabric has an overall surface density of <65g / ㎡, a heat-shielding rate of >65%, and a light fastness of ≥4.

[0013] In some embodiments, the color-reflective undercoat consists of PU adhesive, 30%-50% rutile nano-titanium dioxide, and 0.5%-1% color-matching pigments that match the base fabric color.

[0014] In some embodiments, the modified aluminum powder paste reflective coating consists of PU adhesive, 15%-40% modified aluminum powder paste, and 0.5%-1% warm-toned color pigments.

[0015] In some embodiments, the 60° gloss level of the modified aluminum powder paste reflective surface layer is ≤30. Specifically, the gloss level is tested using a ColorSpectrum CS-300 gloss meter at a 60° incident angle. Tests show that the 60° gloss level of a conventional unmodified aluminum powder paste coating is 70-80, exhibiting a distinct metallic mirror luster, which produces strong glare under sunlight, causing visual fatigue. This invention modifies the aluminum powder paste by adding a composite matting agent of polyethylene wax and silica, reducing the 60° gloss level of the coating to 30 or below, achieving a matte finish. Visual inspection and instrument testing confirm the absence of glare, significantly improving comfort under umbrellas.

[0016] In some embodiments, the areal density of the color-reflective substrate is 12-16 g / m². 2 The surface density of the modified aluminum powder paste reflective surface layer is 4-8 g / m³. 2 And the total areal density of the two coating layers is ≤20g / m³ 2 .

[0017] In some embodiments, the reinforcing base fabric is a 200T@3mm mesh nylon woven fabric treated with silicone waterproofing, with a fabric density of 200 threads / inch, that is, the sum of warp and weft yarns per square inch is 200 threads; the mesh spacing formed by the tear-resistant weaving process is 3mm; and the fiber material is polyamide fiber.

[0018] Secondly, the present invention provides a method for preparing a lightweight coated heat-shielding umbrella fabric, comprising the following steps: Step 1: Provide an areal density <35g / m³ 2 And a reinforced base fabric with a tensile strength ≥200N; Step 2: Apply a color-retaining reflective undercoat coating to the reinforced base fabric and dry it to form a color-retaining reflective undercoat; Step 3: Apply a modified aluminum powder paste reflective coating to the color-preserving reflective underlayer and dry it to form a modified aluminum powder paste reflective surface layer; Specifically, the total surface density of the color-preserving reflective underlayer and the modified aluminum powder paste reflective surface layer is controlled to be ≤20g / m³. 2 This results in an overall surface density of the finished umbrella fabric of <65g / m². 2 The heat-shading rate is >65%.

[0019] In some embodiments, the drying temperature in steps two and three is 110-130°C.

[0020] Thirdly, the present invention provides a method for preparing a modified aluminum powder paste for preparing a modified aluminum powder paste reflective surface layer in a lightweight coated heat shield fabric, comprising: adding 2%-5% of polyethylene wax and silica composite matting agent and warm-toned pigment to the aluminum powder paste for modification treatment, so that the final coating surface has a 60° gloss level ≤30.

[0021] In some embodiments, the mass ratio of the polyethylene wax to silica is 1:1 to 2:1; the modification treatment includes high-speed dispersion and grinding steps, such that the fineness of the modified aluminum powder slurry is ≤15μm.

[0022] Beneficial effects: Compared with the prior art, the present invention has the following beneficial effects: 1. Synergistic breakthrough in ultra-lightweight and high heat-shielding properties: This invention achieves this by selecting a low-weight, high-strength base fabric (area density < 35 g / m²). 2 (Tear strength ≥ 200N), and precisely control the total areal density of the double-layer functional coating ≤ 20g / m³. 2 This achieved a total umbrella fabric weight of <65g / m². 2 More importantly, through the complementary and synergistic effects of the dual-layer structure—a color-retaining reflective underlayer (primarily reflecting visible light) and a modified aluminum powder reflective surface layer (reflecting the entire wavelength, especially compensating for infrared reflection)—a heat-shielding rate of >65% is achieved with an extremely low coating weight, overcoming the technical prejudice in the field that "lightweighting inevitably sacrifices heat shading." Compared with traditional sunshade umbrella fabrics, the umbrella fabric of this invention is more than 35% lighter, the heat-shielding rate can be increased to 69.6%, and there is no glare.

[0023] 2. Significant matting and anti-glare effect: This invention modifies aluminum powder paste by combining polyethylene wax and silica for matting and warm color tone, significantly reducing the 60° gloss of the coating from the conventional ≥70 to ≤30, completely eliminating visual glare caused by metallic luster and significantly improving user comfort.

[0024] 3. Integrated Color Retention and Reflection: The rutile nano-titanium dioxide in the bottom layer of the umbrella fabric of this invention is both a highly efficient reflective particle and, in conjunction with the color-correcting pigments, plays a role in color fixation and retention. The lightfastness of the umbrella fabric of this invention reaches level 4-5 (GB / T8427-2019), which is a significant improvement in color retention compared to conventional high-reflection coatings (usually only level 2-3), effectively avoiding the problems of coating whitening and discoloration.

[0025] 4. Multifunctional integration: In addition to high heat-blocking rate, the lightweight coated heat-blocking umbrella fabric of this invention also has excellent UV protection performance (UPF>2000) and high waterproof performance (hydrostatic pressure level 5, ≥50kPa), realizing the integration of heat blocking, sun protection and waterproofing. Attached Figure Description

[0026] Figure 1This is a schematic diagram of the structure of the lightweight coated heat-shielding umbrella fabric of the present invention; Figure 2 This is a schematic diagram of the preparation method of the lightweight coated heat-shielding umbrella fabric of the present invention; In the diagram: 1. Modified aluminum powder paste reflective surface layer; 2. Color-preserving reflective underlayer; 3. Reinforced base fabric. Detailed Implementation

[0027] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely intended to explain the present application and not to limit it. For those skilled in the art, the present application can be implemented without some of these specific details. The following description of the embodiments is merely to provide a better understanding of the present application by illustrating examples.

[0028] Preparation Example 1: Preparation of modified aluminum powder paste.

[0029] Take 100 parts of commercially available aluminum powder slurry (60% solid content, average particle size 20μm), add 2.5 parts of polyethylene wax powder (melting point 110℃) and hydrophobic fumed silica (specific surface area 200m²). 2 1.0 part (g) of iron oxide red pigment and 0.8 parts of ferric oxide red pigment are dispersed at 1000 rpm for 45 minutes, and then ground twice through a three-roll mill until the fineness is ≤15μm. The product is then discharged to obtain modified aluminum powder paste. When this modified aluminum powder paste is used to prepare a modified aluminum powder paste reflective coating, it is mixed with PU adhesive in a certain proportion and then applied. After drying, the coating has a gloss level of ≤30 at 60°.

[0030] Example 1 like Figure 1-2 As shown, a lightweight coated heat-shielding umbrella fabric with a surface density of 34 g / m² is described. 2 The reinforcing base fabric is a 200T@3mm mesh nylon woven fabric treated with silicone waterproofing. "200T" indicates a fabric density of 200 threads / inch, meaning 200 warp and weft yarns per square inch; "3mm mesh" indicates a 3mm mesh spacing created using a tear-resistant weaving process; and "nylon" refers to the polyamide fiber material. This base fabric has a measured breaking strength of 220N in the warp and 210N in the weft, achieving excellent mechanical properties while maintaining extremely light weight.

[0031] A color-retaining reflective undercoat is coated onto the reinforced base fabric 3. The coating is made from PU adhesive and contains 30% rutile nano-titanium dioxide and 0.5% colorant. The coating is dried at 120℃ and has a surface density of 12 g / m³. 2 , forming a color-reflective underlayer 2.

[0032] Next, a modified aluminum powder paste reflective coating was applied to the color-retaining reflective underlayer 2. The coating was made from PU adhesive and contained 40% of the modified aluminum powder paste prepared according to Preparation Example 1 and 0.5% of the color pigment. The coating was dried at 120°C and had a surface density of 8 g / m³. 2 A modified aluminum powder paste reflective surface layer 1 is formed.

[0033] Ultimately, the overall surface density of the finished umbrella fabric is 54 g / m². 2 It has a heat-blocking rate of 69.6% and a gloss level of 29 at 60°.

[0034] According to report number SHA03-26022142-CS-01 from Shanghai Micro-Spectrum Testing Technology Group Co., Ltd., elemental analysis of the sample was performed according to JY / T 0567-2020 "General Rules for Inductively Coupled Plasma Emission Spectrometry Analysis". The silicon (Si) content in the sample was 1.23%. According to GB / T 14635-2008 "Chemical Analysis Methods for Rare Earth Metals and Their Compounds - Determination of Total Rare Earth Content", the total rare earth oxides (REO, as-received basis) in the sample were 0.23%. It should be noted that due to limitations in the sample system, particulate precipitation occurred during digestion; therefore, the Si content test results are for reference only.

[0035] Example 2 like Figure 1-2 As shown, a lightweight coated heat-shielding umbrella fabric with a surface density of 33 g / m² is used. 2 200T@3mm mesh nylon fabric with silicone waterproof treatment is used as the reinforcing base fabric 3.

[0036] A color-retaining reflective undercoat is coated onto the reinforced base fabric 3. The coating is made from PU adhesive and contains 40% rutile nano-titanium dioxide and 0.8% colorant. The coating is dried at 110℃ and has a surface density of 14 g / m³. 2 , forming a color-reflective underlayer 2.

[0037] Next, a modified aluminum powder paste reflective coating was applied to the color-preserving reflective underlayer 2. The coating was made from PU adhesive and contained 20% of the modified aluminum powder paste prepared according to Preparation Example 1 and 0.8% of the color pigment. The coating was dried at 110°C and had a surface density of 6 g / m³. 2 A modified aluminum powder paste reflective surface layer 1 is formed.

[0038] Ultimately, the overall surface density of the finished umbrella fabric is 53 g / m². 2 It has a heat-blocking rate of 66% and a gloss level of 28 at 60°.

[0039] Example 3 like Figure 1-2As shown, a lightweight coated heat-shielding umbrella fabric uses 200T@3mm mesh nylon woven fabric with an organosilicon waterproof treatment and a surface density of 32g / ㎡ as the reinforcing base fabric 3.

[0040] A color-retaining reflective undercoat is coated onto the reinforced base fabric 3. The coating is made from PU adhesive and contains 50% rutile nano-titanium dioxide and 0.7% colorant. The coating is dried at 130℃ and has a surface density of 16 g / m³. 2 , forming a color-reflective underlayer 2.

[0041] Next, a modified aluminum powder paste reflective coating was applied to the color-retaining reflective underlayer 2. The coating was made from PU adhesive and contained 15% of the modified aluminum powder paste prepared according to Preparation Example 1 and 0.7% of the color pigment. The coating was dried at 130°C and had a surface density of 4 g / m³. 2 A modified aluminum powder paste reflective surface layer 1 is formed.

[0042] Ultimately, the overall surface density of the finished umbrella fabric is 52 g / m². 2 It has a heat-blocking rate of 68% and a gloss level of 29 at 60°.

[0043] Example 4 like Figure 1-2 As shown, a lightweight coated heat-shielding umbrella fabric uses 200T@3mm mesh nylon woven fabric with an organosilicon waterproof treatment and a surface density of 31g / ㎡ as the reinforcing base fabric 3.

[0044] A color-retaining and reflective undercoat is coated onto the reinforced base fabric 3. The coating is made from PU adhesive and contains 45% rutile nano-titanium dioxide and 1% colorant. The coating is dried at 120℃ and has a surface density of 15 g / m³. 2 , forming a color-reflective underlayer 2.

[0045] Next, a modified aluminum powder paste reflective coating was applied to the color-preserving reflective underlayer 2. The coating was made from PU adhesive and contained 30% of the modified aluminum powder paste prepared according to Preparation Example 1 and 1% of the color pigment. The coating was dried at 120°C and had a surface density of 5 g / m³. 2 A modified aluminum powder paste reflective surface layer 1 is formed.

[0046] Ultimately, the overall surface density of the finished umbrella fabric is 51 g / m². 2 It has a heat-blocking rate of 69% and a gloss level of 27 at 60°.

[0047] Example 5 (Third-party testing and verification) Lightweight coated heat-shielding umbrella fabric samples were prepared according to the formula and process of the present invention and submitted to a third-party testing institution: Shenzhen Institute of Metrology and Quality Inspection for testing, report number: WT40103261016545WT3. The results are shown in Table 1 below: Table 1 Performance Test Table for Heat-Shielding Umbrella Fabric The above data shows that the lightweight coated heat-shielding umbrella fabric of the present invention achieves lightweighting while possessing excellent heat-shielding, UV protection, and waterproof performance.

[0048] The reinforcing base fabric used in this invention has an areal density of <35g / m². 2 The 200T@3mm mesh nylon fabric was treated with silicone for waterproofing. Its mechanical properties, as shown in Table 2, were tested by a third-party testing agency according to relevant standards. Table 2 Mechanical Performance Test Table for Heat-Shielding Umbrella Fabric The above data shows that the low basis weight base fabric (<35g / m²) selected in this invention is suitable for use in this invention. 2 It has excellent mechanical properties, which can meet the strength requirements of sunshade umbrella fabric, and provide strong support for achieving overall lightweighting of umbrella fabric.

[0049] In the umbrella fabric of this invention, the color-reflective underlayer contains rutile nano-titanium dioxide and color-correcting pigments, possessing both reflective and color-fixing functions. The light fastness of the umbrella fabric of this invention was tested according to the test method of GB / T 8427-2019 "Textiles - Tests for Color Fastness to Artificial Light: Xenon Arc". The results are as follows: Light fastness (color change) is grade 4-5.

[0050] The results show that the umbrella fabric of the present invention has excellent light fastness (≥4 grade), which significantly improves color retention compared with conventional high-reflection coatings (usually only 2-3 grade), effectively avoiding the problems of coating whitening and discoloration.

[0051] Furthermore, to verify the synergistic effect of the double-layer coating of the present invention, under the same total coating areal density (20 g / m²), 2 Under the following conditions, the heat shielding effects of a single-layer coating and the double-layer coating of the present invention are compared as follows.

[0052] Comparative Example 1 (Single Layer) A lightweight coated heat-shielding umbrella fabric, comprising an areal density of 34 g / m² 2 The 200T@3mm mesh nylon fabric is treated with silicone for waterproofing. A color-retaining, reflective undercoat is applied to the base fabric. The coating is made with PU adhesive and contains 50% nano-titanium dioxide. The coating is dried at 120℃ and has a surface density of 20g / m². 2 The overall surface density of the finished umbrella fabric is 54 g / m². 2 The heat-shading rate is 43%.

[0053] Comparative Example 1 used only a color-retaining reflective underlayer, without a modified aluminum powder paste reflective surface layer. Experimental results show that even with a surface density of 20 g / m², the color-retaining reflective underlayer alone does not significantly reduce surface density. 2 The heat shielding rate is only 43%. This indicates that the nano-titanium dioxide coating alone cannot achieve full-band reflection, and its ability to reflect infrared radiation heat is significantly insufficient, with a heat shielding effect far below the 65% required by this invention.

[0054] Comparative Example 2 (Single-sided layer) A lightweight coated heat-shielding umbrella fabric, comprising an areal density of 34 g / m² 2 A 200T@3mm mesh nylon fabric with silicone waterproofing treatment was used as the base fabric, coated with a modified aluminum powder paste reflective coating. The coating was made from PU adhesive and contained 40% of the modified aluminum powder paste prepared according to Preparation Example 1. The coating was dried at 120°C and had a surface density of 20 g / m². 2 The overall surface density of the finished umbrella fabric is 54 g / m². 2 The heat-shading rate is 57%.

[0055] Comparative Example 2 used only the modified aluminum powder paste reflective surface layer, without the color-preserving reflective underlayer. Experimental results showed that even with a surface density of 20 g / m², the heat-shielding rate of the modified aluminum powder paste reflective surface layer was 57%, higher than the single-underlayer solution, but still below the required 65%. However, due to the use of modified aluminum powder paste, its 60° gloss level was ≤30, with no glare, indicating that the matting modification treatment of this invention can achieve good anti-glare effects when used alone.

[0056] This invention employs a double-layer combination, wherein the color-reflective bottom layer has a surface density of 12 g / m². 2 The density of the modified aluminum powder paste reflective surface is 8 g / m². 2 The total coating surface density remains at 20 g / m². 2 Experimental results show that, under the same total coating surface density, the heat shielding rate of the double-layer combination of the present invention reaches 69.6%, which is 26.6% higher than that of Comparative Example 1 (single bottom layer) and 12.6% higher than that of Comparative Example 2 (single top layer).

[0057] In summary, the comparative data from Comparative Examples 1 and 2 fully demonstrate that a single-layer coating cannot achieve the high heat-shielding target. Whether using only the base layer or only the top layer, the heat-shielding rate cannot reach 65% under the same total coating areal density. The heat-shielding effect of the dual-layer combination of the present invention is significantly better than either single-layer coating, and is higher than the average of the two (50%). There is a significant synergistic effect between the color-preserving reflective base layer and the modified aluminum powder reflective top layer of the present invention, rather than a simple superposition of existing coatings.

[0058] Comparative Example 3 (coating order reversed) The coating sequence of this invention is reversed: a modified aluminum powder reflective layer is first coated onto the base fabric, followed by a color-preserving reflective underlayer. Theoretically, the aluminum powder reflective layer primarily reflects full-spectrum radiant heat, while the color-preserving reflective underlayer primarily reflects visible light and preserves color. When the sequence is reversed, the rutile nano-titanium dioxide of the top layer (originally the underlayer) has limited infrared reflectivity, and the aluminum powder of the underlayer (originally the top layer) is obstructed from reflecting infrared light, making it difficult to fully realize the synergistic effect. Therefore, theoretically, this reversed sequence cannot be applied to low coating surface density (≤20g / m²). 2 The technical effect of achieving a shading rate of >65% under the condition of )

[0059] Comparative Example 4 (Total surface density exceeds the limit) If the total areal density of the coating of the present invention is increased to >20 g / m² 2 For example, color-reflective underlayer 25g / m 2 Modified aluminum powder paste reflective surface layer 15g / m 2 The total areal density of the coating is 40 g / m³. 2 Theoretically, while the heat-shading rate may improve, the overall surface density of the umbrella fabric will increase significantly (estimated to exceed 75 g / m²). 2 This cannot meet the lightweight requirements (<65g / m³). 2 This indicates that there is a critical balance between heat shielding efficiency and lightweighting; the present invention controls the total areal density of the coating to ≤20g / m². 2 It is one of the key technical means to achieve a balance between the two.

[0060] Comparative Example 5 (Aluminum Powder Paste without Matte Finish) If ordinary aluminum powder paste without matting modification is used instead of the modified aluminum powder paste of this invention, theoretically, the 60° gloss of ordinary aluminum powder paste is usually ≥70. After coating, the inner surface of the umbrella fabric will produce a strong metallic luster reflection, which can easily cause visual fatigue (glare). At the same time, the unmodified aluminum powder paste has poor compatibility with the resin system, and the coating is prone to particle agglomeration, affecting the coating uniformity and heat shielding effect. However, this invention modifies the aluminum powder paste by adding a composite matting agent of polyethylene wax and silica and warm-toned pigments. Theoretically, this can reduce the 60° gloss to ≤30 while maintaining a high heat shielding rate, eliminating glare and improving the processing performance of the coating.

[0061] It should be noted that in the test methods of this invention: 1. Umbrella fabric surface density: tested according to the method described in GB / T 4669-2008; 2. Umbrella fabric heat shielding rate: tested according to the method described in GB / T 41560-2022; 3. Umbrella fabric inner surface 60° gloss and glare: tested using a color spectrometer CS-300 gloss meter, with 60° GU≤30 considered as no glare; 4. UV protection performance: tested according to the method described in GB / T18830-2009; 5. Waterproof performance (hydrostatic pressure): tested according to the method described in GB / T 4744-2013; 6. Waterproof performance (wet test): tested according to the method described in GB / T 4745-2012; 7. Tear strength: tested according to the method described in GB / T 3917.2-2009; 8. Breaking strength: tested according to GB / T Tested according to the method described in GB / T 8427-2019; 9. Light fastness: Tested according to the method described in GB / T 8427-2019, and the gray scale grade for color change is evaluated.

[0062] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A lightweight coated heat-shielding umbrella fabric, characterized in that: include: Surface density <35g / m 2 The reinforced base fabric has a tensile strength ≥200N and is treated with silicone waterproofing. The reinforced base fabric is sequentially coated with a color-preserving reflective underlayer and a modified aluminum powder paste reflective surface layer; the color-preserving reflective underlayer contains rutile nano-titanium dioxide reflective particles; the modified aluminum powder paste reflective surface layer contains modified aluminum powder paste that has been matted and tinted, and the modified aluminum powder paste contains 2%-5% polyethylene wax and silica composite matting agent. The overall surface density of the lightweight coated heat-shielding umbrella fabric is <65g / m². 2 It has a heat-blocking rate of >65% and a light fastness of ≥4.

2. The lightweight coated heat-shielding umbrella fabric according to claim 1, characterized in that: The color-reflective undercoat consists of PU adhesive, 30%-50% rutile nano-titanium dioxide, and 0.5%-1% color-matching pigments that match the base fabric color.

3. The lightweight coated heat-shielding umbrella fabric according to claim 1, characterized in that: The modified aluminum powder paste reflective coating consists of PU adhesive, 15%-40% modified aluminum powder paste, and 0.5%-1% warm-toned color pigments.

4. The lightweight coated heat-shielding umbrella fabric according to claim 3, characterized in that: The modified aluminum powder paste reflective surface layer has a gloss level of ≤30 at 60°.

5. The lightweight coated heat-shielding umbrella fabric according to claim 1, characterized in that: The areal density of the color-reflective substrate is 12-16 g / m³. 2 The surface density of the modified aluminum powder paste reflective surface layer is 4-8 g / m³. 2 And the total areal density of the two coating layers is ≤20g / m³ 2 .

6. The lightweight coated heat-shielding umbrella fabric according to claim 1, characterized in that: The reinforced base fabric is a 200T@3mm mesh nylon woven fabric treated with silicone waterproofing, with a fabric density of 200 threads / inch, that is, the sum of warp and weft yarns per square inch is 200 threads; the mesh spacing formed by the tear-resistant weaving process is 3mm; the fiber material is polyamide fiber.

7. A method for preparing a lightweight coated heat-shielding umbrella fabric according to any one of claims 1-6, characterized in that: Includes the following steps: Step 1: Provide an areal density <35g / m³ 2 And a reinforced base fabric with a tensile strength ≥200N; Step 2: Apply a color-retaining reflective undercoat coating to the reinforced base fabric and dry it to form a color-retaining reflective undercoat; Step 3: Apply a modified aluminum powder paste reflective coating to the color-preserving reflective underlayer and dry it to form a modified aluminum powder paste reflective surface layer; Specifically, the total surface density of the color-preserving reflective underlayer and the modified aluminum powder paste reflective surface layer is controlled to be ≤20g / m³. 2 This results in an overall surface density of the finished umbrella fabric of <65g / m². 2 The heat-shading rate is >65%.

8. The method for preparing the lightweight coated heat-shielding umbrella fabric according to claim 7, characterized in that: The drying temperature for steps two and three is 110-130℃.

9. A method for preparing modified aluminum powder paste, characterized in that: The modified aluminum powder paste reflective surface layer used in the lightweight coated heat-shielding umbrella fabric according to any one of claims 1-6 comprises: adding 2%-5% of polyethylene wax and silica composite matting agent and warm-toned pigment to the aluminum powder paste, and performing modification treatment so that the final coating surface has a 60° gloss level ≤30.

10. The method for preparing modified aluminum powder paste according to claim 9, characterized in that: The mass ratio of the polyethylene wax to silica is 1:1 to 2:1; the modification treatment includes high-speed dispersion and grinding steps, so that the fineness of the modified aluminum powder slurry is ≤15μm.

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