Water-washing resistant reflective material hot melt adhesive film and preparation method thereof

Abstract

This invention discloses a hot melt adhesive film for water-resistant reflective materials, which, by weight, comprises: 0-100 parts of polyurethane elastomer with a hardness of ShA 55-60; 0-100 parts of polyurethane elastomer with a hardness of ShA 70; 10-20 parts of modified resin; 0.5-1 part of coupling agent; and 0.5-1 part of antioxidant; wherein the polyurethane elastomer is a polyester-type polyurethane. The total weight of polyurethane elastomers with a hardness of ShA55-60 and ShA70 is 100 parts. The weight ratio of the polyurethane elastomers with a hardness of ShA55-60 to ShA70 is 10:90 to 90:10. This solves the problems of insufficient bonding strength between existing hot melt adhesive films and clothing fabrics and reflective materials, which significantly reduce the original softness of clothing fabrics after bonding, causing stiffness and hardening of the bonded parts, and easy delamination of reflective materials from fabrics after washing, orange peel texture of adhesive layer and reflective surface, as well as cracking and peeling of reflective layer and reduction of reflective effect.

Description

Technical Field

[0001] The invention relates to the field of semiconductor packaging materials technology, specifically to a hot melt adhesive film for water-resistant reflective materials and its preparation method. Background Technology

[0002] As a core functional component of safety warning clothing, the adhesion strength, durability, and user experience of reflective materials directly determine the safety performance and product quality of the clothing. Currently, the industry's bonding and fixing solutions for reflective materials in clothing (reflective fabric, reflective film, reflective strips, reflective transfer labels, etc.) are mainly divided into two systems: physical fixing and adhesive bonding. Adhesive bonding is the mainstream solution for industrial mass production, while physical fixing is often used as an auxiliary reinforcement method. Both types of solutions have been widely applied in the clothing production field. Specific sub-solutions and technical details are as follows: 1. Physically fixed.

[0003] This type of solution involves no adhesive layer and relies on mechanical interlocking and sewing to fix the reflective material to the clothing fabric. It is the most basic and traditional solution in the application of reflective materials in clothing, and it is compatible with various reflective substrates and clothing fabrics, with no risk of adhesive layer failure. However, this type has low production efficiency and high labor costs.

[0004] 2. Adhesive bonding.

[0005] This type of solution is the core method for mass production of reflective materials for clothing. It uses various adhesives to form an adhesive layer, which enables the bonding of reflective materials (glass microbead layer, metal reflective layer, substrate layer) to clothing fabrics (cotton, polyester, nylon, knitted / woven fabrics). Hot melt adhesive bonding is the industry's leading mainstream solution.

[0006] Current hot melt adhesive films and related adhesive technologies used for bonding reflective materials in clothing still suffer from four major shortcomings: bonding performance, weather resistance and durability, process adaptability, and clothing suitability. These shortcomings fail to meet the high standards required for the industrial production and end-use of reflective materials in clothing. Specific deficiencies are as follows: 1. Insufficient core bonding performance, making reflective materials prone to failure and detachment.

[0007] Poor adhesion and holding power between the clothing substrate (knitted fabric, woven fabric, polyester fabric, etc.) and the reflective layer (glass microspheres, metal reflective layer, reflective film), especially insufficient adhesion to reflective glass microspheres, which easily leads to microsphere detachment and displacement, resulting in a significant decrease in the retroreflective intensity of the reflective material, and failing to meet the industry standard requirements for clothing safety warnings.

[0008] Different adhesive systems have performance shortcomings: acrylic adhesives have weak initial tack and are prone to edge lifting and delamination after bonding; polyurethane adhesives are prone to incomplete curing, and their bonding strength is greatly affected by environmental temperature and humidity, and they are prone to bonding failure after long-term use.

[0009] The adhesive film has poor interfacial compatibility with reflective materials and clothing fabrics. After hot-melt bonding, it is prone to localized loose adhesion and air bubbles, making it impossible to achieve uniform and full adhesion, which greatly reduces the overall bonding stability.

[0010] Second, it lacks weather resistance and durability, making it unsuitable for use in all scenarios.

[0011] Poor water wash resistance: Existing adhesive films are difficult to withstand the conventional room temperature water washing and high temperature strong alkaline water washing (≥60℃) processes of clothing. After washing, the adhesive strength drops sharply, and the reflective layer cracks, peels, breaks, or even falls off completely. The shortcomings of acrylic adhesives in high temperature water washing resistance are particularly prominent, while polyurethane adhesives have insufficient dry cleaning resistance and solvent resistance.

[0012] Poor resistance to environmental aging: Adhesives cured with aromatic isocyanates are prone to yellowing under sunlight and high temperature, which not only affects the appearance of clothing, but also reduces the bonding performance. At the same time, they have poor weather resistance and UV resistance, and the adhesive film is prone to brittleness and cracking after outdoor use.

[0013] Third, the poor adaptability of clothing applications affects the wearing experience and the practicality of the product.

[0014] After the adhesive film is formed, it feels hard and stiff: Hot melt adhesive film made of polyurethane system adhesive will cause the reflective parts of the clothing to become stiff after being applied, losing the original softness of the fabric and feeling uncomfortable when wearing it. It is especially unsuitable for bonding thin clothing, close-fitting clothes and moving parts such as cuffs and collars.

[0015] Lack of breathability: Most existing reflective adhesive hot melt films have a dense structure, which will block the breathable pores of clothing fabric after being applied, preventing sweat from evaporating. Wearing them in summer can easily cause stuffiness, stickiness, and even skin discomfort, failing to meet the requirements of clothing comfort.

[0016] Poor color fastness and easy exudation: The additives and colorants in the adhesive film are easy to be exuded to the surface of the fabric, which not only contaminates the clothing substrate, but also leads to a decrease in the color fastness of the reflective material, resulting in color fading and color bleeding, affecting the overall appearance of the clothing.

[0017] Fourth, shortcomings in production processes and storage performance restrict industrial application.

[0018] The processing technology is complicated and the stability is poor: the production of existing adhesives requires strict control of raw materials and processes. Acrylic adhesives are prone to gelation and have a wide molecular weight distribution, resulting in large differences in product performance between batches. The yield rate of hot melt bonding process is low.

[0019] Strict storage requirements and short shelf life: Some polyurethane adhesives are sensitive to storage temperature and humidity, and are prone to premature cross-linking and abnormal viscosity changes. The short storage period increases the storage and control costs at the production end.

[0020] Low process adaptability: Some adhesives require the use of special curing agents and photoinitiators, and need to be processed under special conditions such as light avoidance and oxygen-free conditions. They cannot be adapted to the large-scale hot melt printing and continuous lamination process of reflective clothing materials, resulting in low production efficiency. Summary of the Invention

[0021] The purpose of this invention is to provide a hot melt adhesive film structure for water-resistant reflective materials, which solves the problems of insufficient bonding strength between existing hot melt adhesive films and clothing fabrics and reflective materials, significantly reducing the original softness of clothing fabrics after bonding, causing stiffness and hardening of the bonding parts, and easy delamination of reflective materials from fabrics, orange peel texture of adhesive layer and reflective surface after washing, accompanied by cracking and peeling of reflective layer and reduction of reflective effect.

[0022] This invention is achieved as follows: A hot melt adhesive film for water-resistant reflective materials, comprising, by weight, the following raw materials: 0-100 parts of polyurethane elastomer with a hardness of ShA55-60; 0-100 parts of polyurethane elastomer with a hardness of ShA70. 10-20 parts of modified resin; 0.5-1 part coupling agent; Antioxidant 0.5-1 part; The polyurethane elastomer mentioned above is a polyester-type polyurethane.

[0023] As one embodiment of the present invention, the sum of the weight parts of the polyurethane elastomer with a hardness of ShA55-60 and the polyurethane elastomer with a hardness of ShA70 is 100 parts.

[0024] As one embodiment of the present invention, the weight ratio of the polyurethane elastomer with a hardness of ShA55-60 to the polyurethane elastomer with a hardness of ShA70 is 10:90 to 90:10.

[0025] As one embodiment of the present invention, the modified resin described above is a modified rosin resin.

[0026] As one embodiment of the present invention, the coupling agent described above is KH550 or KH560.

[0027] As one embodiment of the present invention, the antioxidant is selected from one or more of antioxidant 1010, antioxidant 1076, and antioxidant 168.

[0028] As one embodiment of the present invention, the thickness of the hot melt adhesive film is 50-150 μm.

[0029] A method for preparing a water-washable reflective material hot melt adhesive film includes the following steps: S1. Raw material preparation: Select polyurethane elastomers with a hardness of ShA55-60, polyurethane elastomers with a hardness of ShA70, modified resins, coupling agents and antioxidants in parts by weight. S2. Premixing: The polyurethane elastomer with a hardness of ShA55-60 and the polyurethane elastomer with a hardness of ShA70 are initially mixed with the modified resin, and then the coupling agent and antioxidant are added and fully mixed to obtain a mixture. S3. Melt blending and extrusion followed by cutting and granulation: The mixture obtained in step S2 is added to an extrusion device, melt blended at a temperature of 80-120℃, and then extruded and cut into granules to obtain hot melt adhesive granules; S4. Material drying: The prepared hot melt adhesive granules are air-dried at room temperature to remove moisture. S5. Hot melt coating film formation: The hot melt adhesive granules obtained in step S4 are added to the coating equipment, melted at a temperature of 120-160℃, and coated onto the substrate through the coating device. After cooling and shaping, a hot melt adhesive film is formed.

[0030] As one embodiment of the present invention, in step S4 above: the time for air drying at room temperature is 2-6 hours, until there is no obvious moisture on the particle surface and it feels dry to the touch.

[0031] In one embodiment of the present invention, in step S1 above: 50 parts of polyester polyurethane elastomer with a hardness ShA 55-60; 50 parts of polyester polyurethane elastomer with a hardness ShA 70; 20 parts of modified rosin resin; 0.5 parts of coupling agent; and 1 part of antioxidant.

[0032] The beneficial effects of this invention are: 1. The present invention is a functional additive system composed of various polyurethane elastomers with different hardness, modified resins, coupling agents and antioxidants, which can significantly improve the overall performance of the film compared with a single pure polyurethane elastomer. 2. This invention ensures good wetting, penetration, and initial adhesion of the adhesive film to fabrics by using a softer ShA 55 polyurethane elastomer, providing a comfortable softness; while combining it with a harder ShA 70 polyurethane elastomer as a rigid network skeleton, providing cohesive strength, heat resistance, and hydrolysis resistance, allowing the adhesive film to maintain extremely high adhesive strength even after the humid heat and mechanical action of washing. The combination of these two materials, supplemented with functional additives, achieves a balance of rigidity and flexibility, resulting in durable adhesion and meeting the washability requirements of high-end washable reflective materials. Attached Figure Description

[0033] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention, making other features, objects, and characteristics of the invention more apparent. The illustrative embodiments of the invention, along with their descriptions, are used to explain the invention and do not constitute an undue limitation of the invention.

[0034] Figure 1 This is a data diagram illustrating a specific embodiment of the present invention; Figure 2 This is a schematic diagram of the test results of an embodiment of the present invention; Figure 3 This is a schematic diagram of the test results of embodiment two of the present invention. Detailed Implementation

[0035] The following will refer to the appendices in the embodiments of the present invention. Figure 1-3 The technical solutions in the embodiments of the present invention are clearly and completely described herein. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0036] It should be noted that all directional indicators in the embodiments of the present invention (such as the center back, shoulder seam, armhole, collar, corresponding position of the scapula, etc.) are only used to explain the relative positional relationship, unfolding direction, ironing range, etc. of the various structures of the garment pattern under a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0037] This invention provides a hot melt adhesive film for water-resistant reflective materials and its preparation method.

[0038] In reflective materials, such as reflective fabrics and reflective tapes, especially in applications like clothing and bags that require frequent washing, the water resistance of the adhesive backing is crucial.

[0039] Existing single-hardness hot melt adhesive films (polyurethane elastomers) often struggle to balance flexibility, initial adhesion, and cohesive strength after washing: low-hardness films (such as ShA 55-60) have good initial adhesion and a soft feel, but poor heat resistance and strength retention after washing; high-hardness films (such as ShA 70) have good heat and wash resistance, but weak initial adhesion, are too hard, affect the feel of the composite, and are prone to brittleness at low temperatures.

[0040] This invention provides a water-resistant reflective material hot melt adhesive film, the raw material composition of which, by weight, includes: 0-100 parts of polyurethane elastomer with a hardness of ShA55-60; 0-100 parts of polyurethane elastomer with a hardness of ShA70. 10-20 parts of modified resin; 0.5-1 part coupling agent; Antioxidant 0.5-1 part; The polyurethane elastomer is a polyester-type polyurethane.

[0041] The total weight of polyurethane elastomer with hardness ShA55-60 and polyurethane elastomer with hardness ShA70 is 100 parts; and the weight ratio of polyurethane elastomer with hardness ShA55-60 to polyurethane elastomer with hardness ShA70 is 10:90 to 90:10.

[0042] The modified resin is modified rosin resin, the coupling agent is KH550 or KH560, the antioxidant is selected from one or more of antioxidant 1010, antioxidant 1076, and antioxidant 168, and the thickness of the hot melt adhesive film is 50-150μm.

[0043] This invention utilizes a mixture of polyester-type polyurethane elastomers with a hardness of ShA 55-60 and a polyester-type polyurethane elastomer with a hardness of ShA 70, along with modified resins, coupling agents, and antioxidants. The medium-to-low hardness polyurethane elastomer provides excellent initial wettability, softness, and penetration adhesion to the substrate, while the higher hardness polyurethane elastomer acts as a rigid supporting skeleton, providing cohesive strength, heat resistance, and hydrolysis resistance.

[0044] When the two are melt-blended in a specific ratio, they form a certain degree of phase separation and interpenetrating network structure at the microscopic level, thus exhibiting high flexibility and adhesion. By adding a modified resin, which in this embodiment is rosin resin, the initial adhesion to various substrates to be bonded is significantly improved. The addition of a silane coupling agent not only improves the dispersibility of inorganic fillers, but also forms chemical bonds on the surface of the adhesive film and fabric fibers, greatly improving the adhesion retention rate after washing. Antioxidants effectively prevent thermal and oxidative aging during processing and use, ensuring the long-term durability of the hot melt adhesive film.

[0045] This invention also provides a method for preparing a hot melt adhesive film for water-washable reflective materials, comprising the following steps: S1. Raw material preparation: Accurately weigh each raw material according to the formula. Polyurethane elastomer is in granular form, and modified rosin resin is in block or flake form, which need to be crushed beforehand.

[0046] S2. Premixing: Add the weighed polyurethane elastomer granules of two different hardnesses and modified rosin resin fragments to a mixer. Mix at 50-200 rpm for 3-5 minutes at room temperature for initial dry mixing, allowing the resin to initially disperse and adhere to the surface of the polyurethane elastomer granules. While the mixer is running, add the weighed KH550 coupling agent and antioxidant 1010 to the initially mixed material. Maintain the speed of 50-200 rpm and continue mixing for 5-8 minutes until all components appear uniform, obtaining a mixture. During this process, frictional heat can raise the material temperature to 40-50℃, which is beneficial for the dispersion of the coupling agent.

[0047] S3. Melt Blending and Extrusion followed by Granulation: The resulting mixture is fed into the main feed port of a co-rotating twin-screw extruder via a feeder. The temperatures of each section of the twin-screw extruder are set as follows: Zone 1 85℃, Zone 2 95℃, Zone 3 105℃, Zone 4 100℃, and the screw speed is 150 rpm. The material is melt-blended under the conveying, shearing, and mixing action of the screw, and then extruded into strips through the die head. The extruded melt strips are immediately cooled in a water bath at a temperature of 10-20℃, and then dried by a blower before being fed into a pelletizer to be cut into hot melt adhesive granules with a diameter of approximately 3mm and a length of approximately 3mm.

[0048] S4. Material drying: Spread the hot melt adhesive granules on a clean tray and place them in a well-ventilated and dry indoor environment at a temperature of 25±5℃ and a relative humidity of <60% for 4 hours until the particle surface is completely dry and there is no stickiness.

[0049] The drying step removes the moisture adsorbed on the particle surface, preventing bubbles from forming during subsequent hot melt coating and reducing the risk of hydrolytic degradation of the polyurethane elastomer in the molten state.

[0050] S5. Hot-melt coating: The dried hot-melt adhesive granules are added to the hopper of a single-screw extruder coating machine. The temperatures of each section of the single-screw extruder are set as follows: Zone 1 130℃, Zone 2 145℃, Zone 3 155℃, and the die temperature 150℃. The film thickness is controlled to be 100μm ± 5μm by adjusting the die slit gap and the release paper feed speed.

[0051] The adhesive containing reflective microbeads is coated onto the hot melt adhesive film prepared above and cured at 40°C for 24 hours to obtain a reflective layer. The reflective layer is then bonded to the fabric and pressed at 120-150°C for 15 seconds to obtain the final product. like Figure 1 As shown, based on the above method, three sets of exemplary examples and two sets of comparative examples were conducted. The specific core data includes the following: The components and steps of Example 1 include: premixing 100 parts of polyurethane elastomer with a hardness of ShA 55 with 10 parts of rosin resin; adding 1 part of KH550 and 0.5 parts of antioxidant 1010 after mixing; and mixing again. The mixture is then fed into a twin-screw granulator, extruded, and granulated. The granulated particles are placed in a well-ventilated and dry room at 25°C and air-dried for 4 hours. Next, the particles are fed into a single-screw extruder for hot-melt coating at a coating temperature of 150°C and a coating thickness of 100 μm.

[0052] The components and steps of Example 2 include: premixing 100 parts of polyurethane elastomer with a hardness of ShA 55 with 20 parts of rosin resin; adding 1 part of KH550 and 1 part of antioxidant 1010 after mixing; and mixing again. The mixture is then fed into a twin-screw granulator, extruded, and granulated. The granules are placed in a well-ventilated and dry room at 25°C and air-dried for 4 hours. Next, the granules are fed into a single-screw extruder for hot-melt coating at a coating temperature of 150°C and a coating thickness of 100 μm.

[0053] The components and steps of Example 3 include: 50 parts of polyurethane elastomer with a hardness of ShA 55, 50 parts of polyurethane elastomer with a hardness of ShA 70, and 20 parts of rosin resin are premixed. After mixing, 0.5 parts of KH550 and 1 part of antioxidant 1010 are added, and the mixture is mixed again. The mixture is then fed into a twin-screw granulator, extruded, and granulated. The granulated particles are placed in a well-ventilated and dry room at 25°C and air-dried for 4 hours. Next, the particles are fed into a single-screw extruder for hot-melt coating at a coating temperature of 150°C and a coating thickness of 100 μm.

[0054] The components and steps of Comparative Example 1 include: directly feeding 100 parts of polyurethane elastomer with a hardness of ShA 55 into a single screw extruder for hot melt coating, with a coating temperature of 150℃ and a coating thickness of 100μm.

[0055] The components and steps of Comparative Example 2 include: directly feeding 100 parts of polyurethane elastomer with a hardness of ShA 70 into a single screw extruder for hot melt coating, with a coating temperature of 150℃ and a coating thickness of 100μm.

[0056] The performance of the hot melt adhesive films obtained in Examples 1-3 and Comparative Examples 1-2 was tested using the following methods: 1. Water wash resistance test of hot melt adhesive films in Examples 1-3 The reflective material coated in Examples 1-3 was hot-pressed onto polyester fabric, and then placed in a washing machine along with 1.8 kg of wash cloth. The washing temperature was set to 60 degrees Celsius, the spin speed to 1000 rpm, and the washing time to 1.5 hours. Afterward, the cloth was placed in a dryer and dried for 40 minutes. This constitutes one cycle. This process was repeated 50 times to simulate multiple washing processes in actual use, resulting in... Figure 2 result.

[0057] 2. Water wash resistance test after reflective layer bonding: Recoat a piece of polyester fabric with the hot melt adhesive film from Examples 2-3 and Comparative Examples 2-3, respectively, and then hot-press reflective material onto each hot melt adhesive film. Then, place it in a washing machine along with 1.8 kg of wash cloth. Set the washing temperature to 60 degrees Celsius, the spin speed to 1000 rpm, and wash for 1.5 hours. Then, place it in a dryer and dry for 40 minutes. This constitutes one cycle. Repeat 50 cycles to simulate multiple washing processes in actual use, obtaining... Figure 3 result.

[0058] like Figures 2-3 Experimental results and analysis, visual observation, combined with test result images: Example 1: After washing, the surface of the adhesive film is severely damaged, obviously deformed or detached, and loosely attached to the fabric.

[0059] Example 2: After washing, the film has an intact appearance with only very slight wrinkles at the edges, and the adhesion remains good.

[0060] Example 3: After washing with water, the surface of the adhesive film is smooth and there is no delamination, which shows excellent water washing stability.

[0061] 2. Water wash resistance test after adding a reflective layer in Examples 2-3 and Comparative Examples 1-2 Example 2: After washing, the appearance of the film was somewhat incomplete, and there were obvious missing stripes in the center of the reflective layer, indicating that the adhesion was average.

[0062] Example 3: After washing, the film surface is smooth and the reflective layer shows no delamination, demonstrating excellent water resistance and stability.

[0063] Comparative Example 1: After washing, the reflective layer and adhesive film showed localized blistering and edge lifting, indicating weak adhesion to the fabric substrate.

[0064] Comparative Example 2: After washing, the reflective layer and adhesive film showed obvious wrinkling, central and local separation, and a small amount of fiber adhering to the surface, indicating a serious decrease in adhesion.

[0065] The hot melt adhesive film of the present invention in Example 3 achieved a peel strength retention rate of over 99% after water washing, which is much higher than that of Comparative Example 1, Comparative Example 2, Example 1 and Example 2, proving that its water washing resistance is significantly better than the prior art.

[0066] In Example 3, when the ratio of ShA 55 polyurethane elastomer to ShA 70 polyurethane elastomer was 50:50, the retention rate was higher than that of other groups, indicating that this ratio was the preferred choice.

[0067] The hot melt adhesive film for water-resistant reflective materials provided by this invention, through specific component ratios and structural design, can still maintain good peel strength and appearance integrity after water washing, meeting the long-term water-resistant and aging-resistant requirements of reflective materials. Test results verify the rationality and superiority of the formulation and performance characteristics of this invention.

[0068] This invention comprises a functional additive system consisting of various polyurethane elastomers of different hardnesses, modified resins, coupling agents, and antioxidants. Compared to pure polyurethane elastomers, this system significantly improves the overall performance of the adhesive film. Example 3 illustrates the synergistic reinforcing effect of blending polyurethane elastomers of different hardnesses in a specific ratio: the softer ShA 55 polyurethane elastomer ensures good wetting, penetration, and initial adhesion of the adhesive film to the fabric, providing a comfortable softness; combined with the harder ShA 70 polyurethane elastomer, it acts as a rigid network skeleton, providing cohesive strength, heat resistance, and hydrolysis resistance, enabling the adhesive film to maintain extremely high adhesive strength even after the humid heat and mechanical action of washing. The combination of these two components, supplemented by functional additives, achieves a balance of rigidity and flexibility, resulting in durable adhesion, meeting the washability requirements of high-end washable reflective materials for their adhesive backing.

[0069] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0070] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. A hot melt adhesive film for water-resistant reflective materials, characterized in that, The raw material composition, by weight, includes: 0-100 parts of polyurethane elastomer with a hardness of ShA55-60; 0-100 parts of polyurethane elastomer with a hardness of ShA70. 10-20 parts of modified resin; 0.5-1 part coupling agent; Antioxidant 0.5-1 part; The polyurethane elastomer is a polyester-type polyurethane.

2. The hot melt adhesive film for water-resistant reflective materials according to claim 1, characterized in that, The sum of the weight parts of the polyurethane elastomer with a hardness of ShA55-60 and the polyurethane elastomer with a hardness of ShA70 is 100 parts.

3. The hot melt adhesive film for water-resistant reflective materials according to claim 2, characterized in that, The weight ratio of the polyurethane elastomer with a hardness of ShA55-60 to the polyurethane elastomer with a hardness of ShA70 is 10:90 to 90:

10.

4. The hot melt adhesive film for water-resistant reflective materials according to claim 1, characterized in that, The modified resin is a modified rosin resin.

5. The hot melt adhesive film for water-resistant reflective materials according to claim 1, characterized in that, The coupling agent is KH550 or KH560.

6. The hot melt adhesive film for water-resistant reflective materials according to claim 1, characterized in that, The antioxidant is selected from one or more of antioxidant 1010, antioxidant 1076, and antioxidant 168.

7. The hot melt adhesive film for water-resistant reflective materials according to claim 1, characterized in that, The thickness of the hot melt adhesive film is 50-150 μm.

8. A method for preparing a water-washable reflective material hot melt adhesive film, used to prepare the hot melt adhesive film according to any one of claims 1-7, characterized in that, Includes the following steps: S1. Raw material preparation: Select polyurethane elastomers with a hardness of ShA55-60, polyurethane elastomers with a hardness of ShA70, modified resins, coupling agents and antioxidants in parts by weight. S2. Premixing: The polyurethane elastomer with a hardness of ShA55-60 and the polyurethane elastomer with a hardness of ShA70 are initially mixed with the modified resin, and then the coupling agent and antioxidant are added and fully mixed to obtain a mixture. S3. Melt blending and extrusion followed by cutting and granulation: The mixture obtained in step S2 is added to an extrusion device, melt blended at a temperature of 80-120℃, and then extruded and cut into granules to obtain hot melt adhesive granules; S4. Material drying: The prepared hot melt adhesive granules are air-dried at room temperature to remove moisture. S5. Hot melt coating film formation: The hot melt adhesive granules obtained in step S4 are added to the coating equipment, melted at a temperature of 120-160℃, and coated onto the substrate through the coating device. After cooling and shaping, a hot melt adhesive film is formed.

9. The preparation method according to claim 8, characterized in that, In step S4: the drying time at room temperature is 2-6 hours, until there is no obvious moisture on the particle surface and it feels dry to the touch.

10. The preparation method according to claim 8, characterized in that, In step S1: 50 parts of polyester polyurethane elastomer with a hardness of ShA 55-60; 50 parts of polyester polyurethane elastomer with a hardness of ShA 70; 20 parts of modified rosin resin; 0.5 parts of coupling agent; and 1 part of antioxidant.

Images