Thermoplastic polyurethane elastomer, polyurethane hot melt adhesive film, and preparation methods and applications of thermoplastic polyurethane elastomer and polyurethane hot melt adhesive film

Abstract

The invention discloses a thermoplastic polyurethane elastomer, a polyurethane hot melt adhesive film and a preparation method and application of the thermoplastic polyurethane elastomer and the polyurethane hot melt adhesive film, a wide-angle X-ray diffraction pattern of the thermoplastic polyurethane elastomer has a diffraction peak in a range of 2theta = 5-30 degrees in a 300% tensile state, and the grain size D1 is 3-12nm. After unloading recovery, the wide-angle X-ray diffraction peak intensity is attenuated, and the grain size D2 is smaller than 1 nm. The thermoplastic polyurethane elastomer is adopted as a main material, and the polyurethane hot melt adhesive film with remarkable yellowing resistance, high elastic recovery rate and low-temperature processing window can be obtained through cooperation of functional auxiliaries and an extrusion casting process. The material system is particularly suitable for functional layers of humanoid robots and is also suitable for bonding application of flexible substrates. The low-temperature processing characteristic can effectively avoid the thermal damage risk of the high temperature of the traditional hot melt adhesive to the sensitive substrate.

Description

Technical Field

[0001] This invention relates to the field of polyurethane hot melt adhesives, specifically to a thermoplastic polyurethane elastomer, a polyurethane hot melt adhesive film, its preparation method, and its applications. Background Technology

[0002] In the field of hot melt adhesive films, polyurethane hot melt adhesive films are widely used in industries such as clothing, footwear, automotive interiors, and electronics due to their excellent flexibility, abrasion resistance, and chemical resistance. Traditional polyurethane hot melt adhesive films mostly use MDI (diphenylmethane diisocyanate) type isocyanates, which have several drawbacks. During high-temperature processing, they are prone to yellowing, which significantly affects the aesthetics of products with high appearance requirements, such as white or light-colored flexible composite materials. In terms of resilience, they are insufficient, typically with a resilience rate of less than 85%. During long-term use, they are prone to permanent deformation under external forces, failing to meet the requirements of applications with high material elasticity requirements, such as high-end sports shoe materials and elastic fabrics. Although many high-resilience polyurethane hot melt adhesive films have been developed in the market, they generally have high melting points and processing temperatures generally above 140℃, which limits their application on some temperature-sensitive low-temperature substrates.

[0003] Patent WO2024038104A introduces new polyol soft segments and chain extenders through special formulation design to obtain a thermoplastic polyurethane with high resilience and low softening temperature. However, the thermoplastic polyurethane obtained by this technical route has limited resilience, and can only guarantee a resilience rate of more than 90% at 100% elongation. The resilience performance is insufficient at 300% high deformation. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a thermoplastic polyurethane elastomer that uses wide-angle X-ray diffraction (WAXD) to characterize the dynamic crystallinity changes of the polymer, enabling the thermoplastic polyurethane elastomer to be blended with other functional additives through extrusion and casting to obtain a polyurethane hot melt adhesive film with resistance to yellowing, high resilience, and low processing temperature.

[0005] Another object of the present invention is to provide a polyurethane hot melt adhesive film prepared from the polyurethane elastomer, a method for preparing the film, and its application.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a thermoplastic polyurethane elastomer, wherein the thermoplastic polyurethane elastomer comprises the following dynamic process as determined by wide-angle X-ray diffraction (WAXD):

[0008] a) At 300% stretch:

[0009] The wide-angle X-ray diffraction (WAXD) pattern shows diffraction peaks in the range of 2θ = 5 to 30°, and the grain size is D1 = 3 to 12 nm, preferably D1 = 5 to 10 nm.

[0010] b) Unloaded recovery state:

[0011] Wide-angle X-ray diffraction peak intensity attenuation, grain size D2 < 1 nm (no effective crystal structure).

[0012] Preferably, the thermoplastic polyurethane elastomer is obtained by polymerization of isocyanate, polyol and optionally chain extender;

[0013] The isocyanate is one or a combination of two of the following: 4,4'-dicyclohexylmethane diisocyanate, 1,4-cyclohexane diisocyanate, isophorone diisocyanate, phenyldimethyl diisocyanate, and cyclohexanedimethyl diisocyanate; preferably one or a combination of two of the following: 4,4'-dicyclohexylmethane diisocyanate and 1,4-cyclohexane diisocyanate.

[0014] The polyols include any one or a combination of at least two of polycarboxylate polyols, polyether polyols, polycarbonate polyols, and polycaprolactone polyols.

[0015] Preferably, the number average molecular weight (Mn) of the polyol is 1000-4000 g / mol, for example, it can be 1000 g / mol, 1500 g / mol, 1800 g / mol, 2000 g / mol, 2500 g / mol, 3000 g / mol, 3500 g / mol or 4000 g / mol, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range, but 1500-3500 g / mol is further preferred.

[0016] The chain extender comprises any one or a combination of at least two of 1,2-ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, cyclohexanediol, hydroquinone dihydroxyethyl ether, propylenediamine, butanediamine, p-phenylenediamine, biphenyldiamine, and 3,3'-dimethyl-4,4-biphenyldiamine. Preferably, it comprises any one or a combination of at least two of 1,2-ethylene glycol, 1,3-propanediol, and 1,4-butanediol.

[0017] Preferably, the molar amount of NCO groups in the isocyanate is denoted as n1, and the total molar amount of active hydrogen groups in the polyol and chain extender is denoted as n2, with n1:n2 being 1:(0.85-1.2), preferably 1:(0.95-1.1).

[0018] Preferably, the isocyanate comprises 10% to 30% of the total mass of the isocyanate, polyol, and chain extender, with the total mass of the isocyanate being 100%, and more preferably 12% to 25%.

[0019] Preferably, the chain extender comprises 1% to 10% by mass, more preferably 2% to 7%, based on the total mass of the isocyanate, polyol and chain extender as 100%.

[0020] Preferably, the polymerization reaction is carried out in the presence of a catalyst.

[0021] In this invention, the type of catalyst is not specifically limited, and any catalyst known in the art that can catalyze the reaction of active hydrogen with NCO groups to generate urethane / urethane esters is applicable to this invention.

[0022] Preferably, the catalyst comprises any one or a combination of at least two of organotin catalysts, organobismuth catalysts, organozinc catalysts, organotitanium catalysts, and amine catalysts. More preferably, it comprises any one or a combination of at least two of stannous octoate, dibutyltin dilaurate, bismuth neodecanoate, zinc neodecanoate, bismuth isooctanoate, zinc isooctanoate, tetraisopropyl titanate, tetrabutyl titanate, and triethylamine.

[0023] Preferably, the mass of the catalyst is 0.001% to 0.3% based on 100% of the mass of the polyol, more preferably 0.005% to 0.2%.

[0024] Preferably, the polymerization reaction includes, but is not limited to, extrusion or belt processes.

[0025] Preferably, the extrusion process includes the following steps:

[0026] (a) Raw material mixing: The diisocyanate, polyol, chain extender and optional catalyst are mixed in one step according to the formulation ratio;

[0027] (b) Reactive extrusion granulation: The mixture is reactively extruded and granulated using a twin-screw extruder to obtain thermoplastic polyurethane granules.

[0028] Control parameters include:

[0029] Screw speed: 100-250 RPM, preferably 120-200 RPM / min; Extrusion temperature: 100-240℃, preferably 150-220℃;

[0030] Optional hot material temperature: 160~220℃, preferably 180~200℃; granulation cooling water temperature: 5~30℃, preferably 10~20℃;

[0031] (c) Continuous temperature-controlled curing: The thermoplastic polyurethane granules obtained in step (b) are sequentially and continuously passed through three or more independently temperature-controlled hoppers. Control parameters include:

[0032] Storage temperature: 20~120℃, preferably 30~100℃; Total residence time: 4~100h, preferably 8~80h.

[0033] Preferably, the belt conveyor process includes the following steps:

[0034] (1) Static mixing: The diisocyanate, polyol, chain extender and optional catalyst are injected into a static mixer according to the formula ratio, and the temperature is controlled at 40-200℃, preferably 60-180℃.

[0035] (2) Steel strip feeding: The mixture is conveyed to the feed end of the constant temperature steel strip;

[0036] (3) Zoned aggregation: The material sequentially undergoes the following on the steel belt:

[0037] - Polymerization zone: Temperature Tpolymerization = 60~180℃, preferably 80~160℃.

[0038] - Deviation zone: Temperature Tdeviation = 80~200℃, preferably 100~180℃.

[0039] - Cooling zone: Temperature T_cooling = 20~60℃, preferably 20~40℃.

[0040] Steel belt running speed: 0.2–3 m / min, preferably 0.5–2.5 m / min. Total running time of steel belt: 40–200 min, preferably 60–180 min.

[0041] (4) Low temperature cutting: The cooled thermoplastic polyurethane sheet is cut and granulated in a liquid nitrogen atmosphere.

[0042] More preferably, the extrusion process described above is used. This process has advantages such as high continuity, excellent production efficiency, precise control of process parameters, and uniform and stable properties of the resulting thermoplastic polyurethane particles, making it particularly suitable for large-scale industrial production.

[0043] Preferably, the thermoplastic polyurethane elastomer has a Shore hardness of 50A to 80A. More preferably, it has a Shore hardness of 55A to 75A.

[0044] Preferably, the melt temperature (Tm) of the thermoplastic polyurethane elastomer is 100–140°C. More preferably, it is 110–130°C.

[0045] In a second aspect, the present invention provides a polyurethane hot melt adhesive film, which is obtained by casting and extrusion of a thermoplastic polyurethane elastomer as described in the first aspect.

[0046] Furthermore, the preparation process of the polyurethane hot melt adhesive film includes the following steps: The thermoplastic polyurethane elastomer particles are then transferred to a high-speed mixer, and functional additives are added, followed by stirring for 2–3 hours. The uniformly mixed material is added to the feeding device of a single or twin-screw extruder, and a film with a thickness of 0.03–0.2 mm is formed by a casting film forming machine. The casting extrusion temperature is 100–200℃, preferably 120–180℃, and the screw speed is 100–200 RPM / min, preferably 120–180 RPM / min.

[0047] Preferably, the thermoplastic polyurethane elastomer particles are first dried in a drying tower at 60-90°C, and the moisture content of the particles is measured to be less than 0.1%.

[0048] Furthermore, the functional additives include one or more combinations of lubricants and anti-aging additives.

[0049] Furthermore, the amount of the functional additives added accounts for 0.3-7% of the thermoplastic polyurethane elastomer particles, preferably 0.5-5%.

[0050] The lubricant is one or more selected from Fischer-Tropsch wax, montmorillonite wax, polyethylene wax, and N,N'-ethylene bis-stearamide. Polyethylene wax and N,N'-ethylene bis-stearamide are preferred.

[0051] The anti-aging additive is a combination of benzotriazole light stabilizer and phosphite antioxidant, with a mass ratio of benzotriazole light stabilizer to phosphite antioxidant of 1–4:1, preferably 2–3:1. Furthermore, the polyurethane hot melt adhesive film has a 300% resilience of ≥90%, preferably ≥92%.

[0052] Furthermore, the activation temperature of the polyurethane hot melt adhesive film is 100–145°C, preferably 115–140°C.

[0053] Furthermore, the polyurethane hot melt adhesive film has a yellowing resistance rating of ≥4.0 over 7*24h, preferably ≥4.5.

[0054] Furthermore, the present invention also provides applications of the polyurethane hot melt adhesive film. The polyurethane hot melt adhesive film is suitable for the functional layers of humanoid robots:

[0055] Especially for functional layers in any of the following positions of a humanoid robot:

[0056] (A) Epidermal covering layer;

[0057] (B) The flexible substrate of electronic skin;

[0058] (C) A flexible actuation layer having biomimetic muscle function;

[0059] Furthermore, the polyurethane hot melt adhesive film serves as a flexible substrate bonding layer for laminating clothing substrates, shoe upper substrates, or medical dressing substrates.

[0060] The features and effective results of this invention are as follows: by using thermoplastic polyurethane elastomers with specific dynamic crystallization change characteristics, polyurethane hot melt adhesive films with high resilience, low processing temperature and resistance to yellowing can be obtained.

[0061] In a preferred embodiment of the present invention, the polyurethane hot melt adhesive film has a 300% resilience rate ≥90%, an activation temperature of 110~145℃, and a yellowing resistance grade ≥4.0 after 7*24h. Detailed Implementation

[0062] The following embodiments will further illustrate the method provided by the present invention, but the present invention is not limited to the listed embodiments, and should also include any other known modifications within the scope of the claims of the present invention.

[0063] The main raw materials used and their sources in the various embodiments and comparative examples of this invention are as follows:

[0064]

[0065] In the following specific embodiments of the present invention, the main test methods for thermoplastic polyurethane elastomers and polyurethane hot melt adhesive films are as follows:

[0066] (1) Grain size D

[0067] In-situ tensile X-ray diffraction (XRD) was used for testing.

[0068] Equipment: Xeuss 3.0 SAXS / WAXS diffractometer

[0069] Test process:

[0070] The thermoplastic polyurethane elastomer samples were cut into dumbbell shapes (ASTM D638 standard), and XRD wide-angle data (5–30°2θ) were collected in the initial state.

[0071] The grain size D1 was calculated at 300% strain under constant stretching rate (50 mm / min) to the target deformation. XRD wide-angle data (5–30°2θ) were collected while the grain was held in the tensile state.

[0072] Unload the tensile force, hold for 1 minute, collect XRD wide-angle data (5~30°2θ), and calculate the recovered grain size D2 using the Scherrer formula.

[0073] Scherrer's formula:

[0074]

[0075] in:

[0076] D: Grain size (unit: nanometers, nm);

[0077] K: Scherrer constant (taken as 0.89);

[0078] λ: Wavelength of X-rays (unit: angstrom) Cu Kα radiation );

[0079] β: Full width at half maximum (FWHM) of the diffraction peak, which needs to be deducted for instrument broadening effect, and is expressed in radians (rad).

[0080] θ: Bragg angle (in degrees).

[0081] (2) Hardness

[0082] The hardness was obtained using a Shore hardness tester according to the method in ASTM D2240-05.

[0083] (3) Melting temperature (T) m )

[0084] Mettler DSC test was used.

[0085] First scan: Hold at -60℃ for 1 min, then start heating, with a temperature range of -60℃ to 230℃ and a heating rate of 20℃ / min. Hold at 230℃ for 2 min, then start cooling, with a temperature range of 230℃ to -60℃ and a cooling rate of 10℃ / min. Hold at -60℃ for 10 min.

[0086] The second scan repeated the conditions of the first scan. The peak value of crystallization melting in the second scan was recorded as the melting temperature (T). m ).

[0087] (4) Rebound rate R%

[0088] A polyurethane hot melt adhesive film measuring 127mm in length, 30mm in width, and 0.05mm in thickness was stretched to 300% and held for 1 minute. After being released and allowed to recover for 1 minute, its length L was measured.

[0089] Rebound rate:

[0090] (5) Optimal activation temperature

[0091] The Q-Lab hot melt adhesive film was used to test the bonding strength of 0.05mm polyurethane hot melt adhesive film in the bonding temperature range of 80 to 160℃, and the temperature corresponding to the highest bonding strength was taken as the optimal activation temperature.

[0092] (6) 7*24h yellowing resistance rating

[0093] Testing equipment: Ultraviolet aging test chamber (QUV).

[0094] Wavelength: UVA-340.

[0095] Temperature: 50℃±3℃.

[0096] Humidity: 50% ± 5% RH.

[0097] Evaluation metric: Color difference value (ΔE), measured using a colorimeter to measure the color change before and after yellowing.

[0098] Visual rating: Compare with a standard gray card or color swatch (such as ISO 105-A02).

[0099] In this application embodiment, "parts" refers to "parts by mass".

[0100] Example 1

[0101] A thermoplastic polyurethane elastomer and its preparation method are disclosed. The preparation method is as follows: by weight, 1 part of PEBA-2000, 0.284 parts of HMDI, 0.057 parts of BDO, and 0.0002 parts of stannous octoate are mixed evenly. The mixture is then poured into a twin-screw extruder for reaction using an extrusion process. After granulation and continuous temperature control, the mixture is cured to obtain thermoplastic polyurethane elastomer particles.

[0102] The extrusion process parameters are as follows: main machine speed 180 RPM / min, extrusion reaction temperature 180℃, and granulation water temperature 10℃.

[0103] Among them, the continuous temperature-controlled post-fermentation parameters are:

[0104] The particles pass through the following 5 independently temperature-controlled hoppers in sequence.

[0105] Silo sequence Temperature control Duration of stay Silo 1 30℃ 4h 2 silos 50℃ 12h 3 silos 70℃ 12h 4 silos 50℃ 4h 5 silos 30℃ 4h

[0106] The resulting thermoplastic polyurethane elastomer particles were then injection molded into 2mm sheets, and the tests performed on them were as shown in Table 1.

[0107] A polyurethane hot melt adhesive film and its preparation method are disclosed. The preparation method is as follows: 94 parts of the thermoplastic polyurethane elastomer prepared in this embodiment, 3 parts of polyethylene wax, 2 parts of 2-(2'-hydroxy-3',5'-di-tert-pentylphenyl)benzotriazole, and 1 part of bis(2,4-di-tert-butylphenol) pentaerythritol diphosphite are mixed in a high-speed mixer for 30 min, and then extruded and granulated using a twin-screw extruder. The extruded granules are dried in an 80℃ drying tower for 1 h, and the moisture content of the granules is measured to be less than 0.1%. The dried granules are then processed into an adhesive film with a thickness of 0.05 mm using a casting film forming machine. The casting extrusion temperature is 155℃, and the screw speed is 160 RPM / min. The evaluation results are shown in Table 1.

[0108] Example 2

[0109] A thermoplastic polyurethane elastomer and its preparation method are disclosed. The preparation method is as follows: by weight, 1 part of PEBA-2500, 0.246 parts of HMDI, 0.0532 parts of BDO, and 0.0002 parts of stannous octoate are mixed evenly. The mixture is then poured into a twin-screw extruder for reaction using a one-step extrusion process. After granulation and continuous temperature control, the mixture is cured to obtain thermoplastic polyurethane elastomer particles.

[0110] The extrusion process parameters are as follows: main machine speed 180 RPM / min, extrusion reaction temperature 190℃, and granulation water temperature 10℃.

[0111] Among them, the continuous temperature-controlled post-fermentation parameters are:

[0112] The particles pass through the following 5 independently temperature-controlled hoppers in sequence.

[0113] Silo sequence Temperature control Duration of stay Silo 1 40℃ 4h 2 silos 60℃ 12h 3 silos 80℃ 12h 4 silos 60℃ 4h 5 silos 40℃ 4h

[0114] The resulting thermoplastic polyurethane elastomer particles were then injection molded into 2mm sheets, and the tests performed on them were as shown in Table 1.

[0115] A polyurethane hot melt adhesive film and its preparation method are disclosed. The preparation method is as follows: 96 parts of the thermoplastic polyurethane elastomer prepared in this embodiment, 2 parts of polyethylene wax, 1 part of 2-(2'-hydroxy-3',5'-di-tert-pentylphenyl)benzotriazole, and 1 part of bis(2,4-di-tert-butylphenol) pentaerythritol diphosphite are mixed in a high-speed mixer for 30 min, and then extruded and granulated using a twin-screw extruder. The extruded granules are dried in an 80℃ drying tower for 1 h, and the moisture content of the granules is measured to be less than 0.1%. The dried granules are then used to form an adhesive film with a thickness of 0.05 mm using a casting film forming machine. The casting extrusion temperature is 160℃, and the screw speed is 160 RPM / min. The evaluation results are shown in Table 1.

[0116] Example 3

[0117] A thermoplastic polyurethane elastomer and its preparation method are disclosed. The preparation method is as follows: by weight, 1 part of PBHA-2000, 0.305 parts of HMDI, 0.0647 parts of BDO, and 0.0002 parts of stannous octoate are mixed evenly. The mixture is then poured into a twin-screw extruder for reaction using a one-step process. After granulation and continuous temperature control, the mixture is cured to obtain thermoplastic polyurethane elastomer particles.

[0118] The extrusion process parameters are as follows: main machine speed 180 RPM / min, extrusion reaction temperature 180℃, and granulation water temperature 10℃.

[0119] Among them, the continuous temperature-controlled post-fermentation parameters are:

[0120] The particles pass through the following 5 independently temperature-controlled hoppers in sequence.

[0121]

[0122]

[0123] The resulting thermoplastic polyurethane elastomer particles were then injection molded into 2mm sheets, and the tests performed on them were as shown in Table 1.

[0124] A polyurethane hot melt adhesive film and its preparation method are disclosed. The preparation method is as follows: 93 parts of the thermoplastic polyurethane elastomer prepared in this embodiment, 4 parts of N,N'-ethylene bis-stearamide, 2 parts of 2-(2'-hydroxy-3',5'-di-tert-pentylphenyl)benzotriazole, and 1 part of bis(2,4-di-tert-butylphenol) pentaerythritol diphosphite are mixed in a high-speed mixer for 30 min, and then extruded and granulated using a twin-screw extruder. The extruded granules are dried in an 80°C drying tower for 1 h, and the moisture content of the granules is measured to be less than 0.1%. The dried granules are then processed into an adhesive film with a thickness of 0.05 mm using a casting film forming machine. The casting extrusion temperature is 155°C, and the screw speed is 160 RPM / min. The evaluation results are shown in Table 1.

[0125] Example 4

[0126] A thermoplastic polyurethane elastomer and its preparation method are disclosed. The preparation method is as follows: by weight, 1 part of PBHA-2500, 0.235 parts of HMDI, 0.0464 parts of BDO, and 0.0002 parts of stannous octoate are mixed evenly. The mixture is then poured into a twin-screw extruder for reaction using a one-step process. After granulation and continuous temperature control, the mixture is cured to obtain thermoplastic polyurethane elastomer particles.

[0127] The extrusion process parameters are as follows: main machine speed 180 RPM / min, extrusion reaction temperature 190℃, and granulation water temperature 10℃.

[0128] Among them, the continuous temperature-controlled post-fermentation parameters are:

[0129] The particles pass through the following 5 independently temperature-controlled hoppers in sequence.

[0130] Silo sequence Temperature control Duration of stay Silo 1 40℃ 4h 2 silos 60℃ 12h 3 silos 80℃ 12h 4 silos 60℃ 4h 5 silos 40℃ 4h

[0131] The resulting thermoplastic polyurethane elastomer particles were then injection molded into 2mm sheets, and the tests performed on them were as shown in Table 1.

[0132] A polyurethane hot melt adhesive film and its preparation method are disclosed. The preparation method is as follows: 94 parts of thermoplastic polyurethane elastomer provided in the examples, 3 parts of N,N'-ethylene bis-stearamide, 2 parts of 2-(2'-hydroxy-3',5'-di-tert-pentylphenyl)benzotriazole, and 1 part of bis(2,4-di-tert-butylphenol) pentaerythritol diphosphite are mixed in a high-speed mixer for 30 min, and then extruded and granulated using a twin-screw extruder. The extruded granules are dried in a drying tower at 80℃ for 1 h, and the moisture content of the granules is measured to be less than 0.1%. The dried granules are then processed into an adhesive film with a thickness of 0.05 mm using a casting film forming machine. The casting extrusion temperature is 165℃, and the screw speed is 160 RPM / min. The evaluation results are shown in Table 1.

[0133] Example 5

[0134] A thermoplastic polyurethane elastomer and its preparation method are disclosed. The preparation method is as follows: by weight, 1 part of PCL-2000, 0.313 parts of HMDI, 0.071 parts of BDO, and 0.0002 parts of stannous octoate are mixed evenly. The mixture is then poured into a twin-screw extruder for reaction using a one-step process. After granulation and continuous temperature control, the mixture is cured to obtain thermoplastic polyurethane elastomer particles.

[0135] The extrusion process parameters are as follows: main machine speed 180 RPM / min, extrusion reaction temperature 180℃, and granulation water temperature 10℃.

[0136] Among them, the continuous temperature-controlled post-fermentation parameters are:

[0137] The particles pass through the following 5 independently temperature-controlled hoppers in sequence.

[0138] Silo sequence Temperature control Duration of stay Silo 1 30℃ 4h 2 silos 50℃ 12h 3 silos 70℃ 12h 4 silos 50℃ 4h 5 silos 30℃ 4h

[0139] The resulting thermoplastic polyurethane elastomer particles were then injection molded into 2mm sheets, and the tests performed on them were as shown in Table 1.

[0140] A polyurethane hot melt adhesive film and its preparation method are disclosed. The preparation method is as follows: 93 parts of the thermoplastic polyurethane elastomer prepared in this embodiment, 4 parts of N,N'-ethylene bis-stearamide, 2 parts of 2-(2'-hydroxy-3',5'-di-tert-pentylphenyl)benzotriazole, and 1 part of bis(2,4-di-tert-butylphenol) pentaerythritol diphosphite are mixed in a high-speed mixer for 30 min, and then extruded and granulated using a twin-screw extruder. The extruded granules are dried in a drying tower at 80℃ for 1 h, and the moisture content of the granules is measured to be less than 0.1%. The dried granules are then processed into an adhesive film with a thickness of 0.05 mm using a casting film forming machine. The casting extrusion temperature is 160℃, and the screw speed is 160 RPM / min. The evaluation results are shown in Table 1.

[0141] Example 6

[0142] A thermoplastic polyurethane elastomer and its preparation method are disclosed. The preparation method is as follows: by weight, 1 part of PCL-2500, 0.252 parts of HMDI, 0.0485 parts of BDO, and 0.0002 parts of stannous octoate are mixed evenly. The mixture is then poured into a twin-screw extruder for reaction using a one-step process. After granulation and continuous temperature control, the mixture is cured to obtain thermoplastic polyurethane elastomer particles.

[0143] The extrusion process parameters are as follows: main machine speed 180 RPM / min, extrusion reaction temperature 180℃, and granulation water temperature 10℃.

[0144] Among them, the continuous temperature-controlled post-fermentation parameters are:

[0145] The particles pass through the following 5 independently temperature-controlled hoppers in sequence.

[0146] Silo sequence Temperature control Duration of stay Silo 1 30℃ 4h 2 silos 50℃ 12h 3 silos 70℃ 12h 4 silos 50℃ 4h 5 silos 30℃ 4h

[0147] The resulting thermoplastic polyurethane elastomer particles were then injection molded into 2mm sheets, and the tests performed on them were as shown in Table 1.

[0148] A polyurethane hot melt adhesive film and its preparation method are disclosed. The preparation method is as follows: 94 parts of the thermoplastic polyurethane elastomer prepared in this embodiment, 3 parts of N,N'-ethylene bis-stearamide, 2 parts of 2-(2'-hydroxy-3',5'-di-tert-pentylphenyl)benzotriazole, and 1 part of bis(2,4-di-tert-butylphenol) pentaerythritol diphosphite are mixed in a high-speed mixer for 30 min, and then extruded and granulated using a twin-screw extruder. The extruded granules are dried in an 80°C drying tower for 1 h, and the moisture content of the granules is measured to be less than 0.1%. The dried granules are then used to form an adhesive film with a thickness of 0.05 mm using a casting film forming machine. The casting extrusion temperature is 165°C, and the screw speed is 160 RPM / min. The evaluation results are shown in Table 1.

[0149] Example 7

[0150] A thermoplastic polyurethane elastomer and its preparation method are disclosed. The preparation method is as follows: by weight, 1 part of PBHA-2500, 0.212 parts of CHDI, 0.0861 parts of BDO, and 0.0002 parts of stannous octoate are mixed evenly. The mixture is then poured into a twin-screw extruder for reaction using a one-step process. After granulation and continuous temperature control, the mixture is cured to obtain thermoplastic polyurethane elastomer particles.

[0151] The extrusion process parameters are as follows: main machine speed 180 RPM / min, extrusion reaction temperature 190℃, and granulation water temperature 10℃.

[0152] Among them, the continuous temperature-controlled post-fermentation parameters are:

[0153] The particles pass through the following 5 independently temperature-controlled hoppers in sequence.

[0154] Silo sequence Temperature control Duration of stay Silo 1 40℃ 4h 2 silos 60℃ 12h 3 silos 80℃ 12h 4 silos 60℃ 4h 5 silos 40℃ 4h

[0155] The resulting thermoplastic polyurethane elastomer particles were then injection molded into 2mm sheets, and the tests performed on them were as shown in Table 1.

[0156] A polyurethane hot melt adhesive film and its preparation method are disclosed. The preparation method is as follows: 94 parts of thermoplastic polyurethane elastomer provided in the examples, 3 parts of N,N'-ethylene bis-stearamide, 2 parts of 2-(2'-hydroxy-3',5'-di-tert-pentylphenyl)benzotriazole, and 1 part of bis(2,4-di-tert-butylphenol) pentaerythritol diphosphite are mixed in a high-speed mixer for 30 min, and then extruded and granulated using a twin-screw extruder. The extruded granules are dried in a drying tower at 80℃ for 1 h, and the moisture content of the granules is measured to be less than 0.1%. The dried granules are then processed into an adhesive film with a thickness of 0.05 mm using a casting film forming machine. The casting extrusion temperature is 165℃, and the screw speed is 160 RPM / min. The evaluation results are shown in Table 1.

[0157] Example 8

[0158] A thermoplastic polyurethane elastomer and its preparation method are disclosed. The preparation method is as follows: by weight, 1 part of PCL-2000, 0.241 parts of CHDI, 0.092 parts of BDO, and 0.0002 parts of stannous octoate are mixed evenly. The mixture is then poured into a twin-screw extruder for reaction using a one-step process. After granulation and continuous temperature control, the mixture is cured to obtain thermoplastic polyurethane elastomer particles.

[0159] The extrusion process parameters are as follows: main machine speed 180 RPM / min, extrusion reaction temperature 180℃, and granulation water temperature 10℃.

[0160] Among them, the continuous temperature-controlled post-fermentation parameters are:

[0161] The particles pass through the following 5 independently temperature-controlled hoppers in sequence.

[0162] Silo sequence Temperature control Duration of stay Silo 1 30℃ 4h 2 silos 50℃ 12h 3 silos 70℃ 12h 4 silos 50℃ 4h 5 silos 30℃ 4h

[0163] The resulting thermoplastic polyurethane elastomer particles were then injection molded into 2mm sheets, and the tests performed on them were as shown in Table 1.

[0164] A polyurethane hot melt adhesive film and its preparation method are disclosed. The preparation method is as follows: 93 parts of the thermoplastic polyurethane elastomer prepared in this embodiment, 4 parts of N,N'-ethylene bis-stearamide, 2 parts of 2-(2'-hydroxy-3',5'-di-tert-pentylphenyl)benzotriazole, and 1 part of bis(2,4-di-tert-butylphenol) pentaerythritol diphosphite are mixed in a high-speed mixer for 30 min, and then extruded and granulated using a twin-screw extruder. The extruded granules are dried in a drying tower at 80℃ for 1 h, and the moisture content of the granules is measured to be less than 0.1%. The dried granules are then processed into an adhesive film with a thickness of 0.05 mm using a casting film forming machine. The casting extrusion temperature is 160℃, and the screw speed is 160 RPM / min. The evaluation results are shown in Table 1.

[0165] Comparative Example 1

[0166] A thermoplastic polyurethane elastomer and its preparation method are disclosed. The preparation method is as follows: by weight, 1 part of PBA-2000, 0.263 parts of MDI, 0.0522 parts of BDO, and 0.0002 parts of stannous octoate are mixed evenly. The mixture is then poured into a twin-screw extruder for reaction using a one-step process. After granulation and continuous temperature control, the mixture is cured to obtain thermoplastic polyurethane elastomer particles.

[0167] The extrusion process parameters are as follows: main machine speed 180 RPM / min, extrusion reaction temperature 180℃, and granulation water temperature 10℃.

[0168] Among them, the continuous temperature-controlled post-fermentation parameters are:

[0169] The particles pass through the following 5 independently temperature-controlled hoppers in sequence.

[0170] Silo sequence Temperature control Duration of stay Silo 1 30℃ 4h 2 silos 50℃ 12h 3 silos 70℃ 12h 4 silos 50℃ 4h 5 silos 30℃ 4h

[0171] The resulting thermoplastic polyurethane elastomer particles were then injection molded into 2mm sheets, and the tests performed on them were as shown in Table 1.

[0172] A polyurethane hot melt adhesive film and its preparation method are disclosed. The preparation method is as follows: 94 parts of thermoplastic polyurethane elastomer provided in the examples, 3 parts of polyethylene wax, 2 parts of 2-(2'-hydroxy-3',5'-di-tert-pentylphenyl)benzotriazole, and 1 part of bis(2,4-di-tert-butylphenol) pentaerythritol diphosphite are mixed in a high-speed mixer for 30 min, and then extruded and granulated using a twin-screw extruder. The extruded granules are dried in an 80°C drying tower for 1 h, and the moisture content of the granules is measured to be less than 0.1%. The dried granules are then processed into an adhesive film with a thickness of 0.05 mm using a casting film forming machine. The casting extrusion temperature is 155°C, and the screw speed is 160 RPM / min. The evaluation results are shown in Table 1.

[0173] Comparative Example 2

[0174] A thermoplastic polyurethane elastomer and its preparation method are disclosed. The preparation method is as follows: by weight, 1 part of PBHA-2000, 0.28 parts of MDI, 0.057 parts of BDO, and 0.0002 parts of stannous octoate are mixed evenly. The mixture is then poured into a twin-screw extruder for reaction using a one-step process. After granulation and continuous temperature control, the mixture is cured to obtain thermoplastic polyurethane elastomer particles.

[0175] The extrusion process parameters are as follows: main machine speed 180 RPM / min, extrusion reaction temperature 180℃, and granulation water temperature 10℃.

[0176] Among them, the continuous temperature-controlled post-fermentation parameters are:

[0177] The particles pass through the following 5 independently temperature-controlled hoppers in sequence.

[0178] Silo sequence Temperature control Duration of stay Silo 1 30℃ 4h 2 silos 50℃ 12h 3 silos 70℃ 12h 4 silos 50℃ 4h 5 silos 30℃ 4h

[0179] The resulting thermoplastic polyurethane elastomer particles were then injection molded into 2mm sheets, and the tests performed on them were as shown in Table 1.

[0180] A polyurethane hot melt adhesive film and its preparation method are disclosed. The preparation method is as follows: 93 parts of thermoplastic polyurethane elastomer provided in the examples, 4 parts of N,N'-ethylene bis-stearamide, 2 parts of 2-(2'-hydroxy-3',5'-di-tert-pentylphenyl)benzotriazole, and 1 part of bis(2,4-di-tert-butylphenol) pentaerythritol diphosphite are mixed in a high-speed mixer for 30 min, and then extruded and granulated using a twin-screw extruder. The extruded granules are dried in a drying tower at 80℃ for 1 h, and the moisture content of the granules is measured to be less than 0.1%. The dried granules are then processed into an adhesive film with a thickness of 0.05 mm using a casting film forming machine. The casting extrusion temperature is 155℃, and the screw speed is 160 RPM / min. The evaluation results are shown in Table 1.

[0181] Comparative Example 3

[0182] A thermoplastic polyurethane elastomer and its preparation method are disclosed. The preparation method is as follows: by weight, 1 part of PCL-2000, 0.265 parts of MDI, 0.052 parts of BDO, and 0.0004 parts of stannous octoate are mixed evenly. The mixture is then poured into a twin-screw extruder for reaction using a one-step process. After granulation and continuous temperature control, the mixture is cured to obtain thermoplastic polyurethane elastomer particles.

[0183] The extrusion process parameters are as follows: main machine speed 180 RPM / min, extrusion reaction temperature 180℃, and granulation water temperature 10℃.

[0184] Among them, the continuous temperature-controlled post-fermentation parameters are:

[0185] The particles pass through the following 5 independently temperature-controlled hoppers in sequence.

[0186]

[0187]

[0188] The resulting thermoplastic polyurethane elastomer particles were then injection molded into 2mm sheets, and the tests performed on them were as shown in Table 1.

[0189] A polyurethane hot melt adhesive film and its preparation method are disclosed. The preparation method is as follows: 93 parts of thermoplastic polyurethane elastomer provided in the examples, 4 parts of N,N'-ethylene bis-stearamide, 2 parts of 2-(2'-hydroxy-3',5'-di-tert-pentylphenyl)benzotriazole, and 1 part of bis(2,4-di-tert-butylphenol) pentaerythritol diphosphite are mixed in a high-speed mixer for 30 min, and then extruded and granulated using a twin-screw extruder. The extruded granules are dried in a drying tower at 80℃ for 1 h, and the moisture content of the granules is measured to be less than 0.1%. The dried granules are then processed into an adhesive film with a thickness of 0.05 mm using a casting film forming machine. The casting extrusion temperature is 160℃, and the screw speed is 160 RPM / min. The evaluation results are shown in Table 1.

[0190] Comparative Example 4

[0191] A thermoplastic polyurethane elastomer and its preparation method are disclosed. The preparation method is as follows: by weight, 1 part of PBA-2000, 0.264 parts of HMDI, 0.0455 parts of BDO, and 0.0002 parts of stannous octoate are mixed evenly. The mixture is then poured into a twin-screw extruder for reaction using a one-step process. After granulation and post-curing, thermoplastic polyurethane elastomer particles are obtained.

[0192] The resulting thermoplastic polyurethane elastomer particles were then injection molded into 2mm sheets, and the tests performed on them were as shown in Table 1.

[0193] A polyurethane hot melt adhesive film and its preparation method are disclosed. The preparation method is as follows: 93 parts of thermoplastic polyurethane elastomer provided in the examples, 4 parts of N,N'-ethylene bis-stearamide, 2 parts of 2-(2'-hydroxy-3',5'-di-tert-pentylphenyl)benzotriazole, and 1 part of bis(2,4-di-tert-butylphenol) pentaerythritol diphosphite are mixed in a high-speed mixer for 30 min, and then extruded and granulated using a twin-screw extruder. The extruded granules are dried in a drying tower at 80℃ for 1 h, and the moisture content of the granules is measured to be less than 0.1%. The dried granules are then processed into an adhesive film with a thickness of 0.05 mm using a casting film forming machine. The casting extrusion temperature is 155℃, and the screw speed is 160 RPM / min. The evaluation results are shown in Table 1.

[0194] Comparative Example 5

[0195] A thermoplastic polyurethane elastomer and its preparation method are disclosed. The preparation method is as follows: by weight, 1 part of PTMEG-2000, 0.343 parts of HMDI, 0.0682 parts of BDO, and 0.0004 parts of stannous octoate are mixed evenly. The mixture is then poured into a twin-screw extruder for reaction using a one-step process. After granulation and post-curing, thermoplastic polyurethane elastomer particles are obtained.

[0196] The resulting thermoplastic polyurethane elastomer particles were then injection molded into 2mm sheets, and the tests performed on them were as shown in Table 1.

[0197] A polyurethane hot melt adhesive film and its preparation method are disclosed. The preparation method is as follows: 93 parts of thermoplastic polyurethane elastomer provided in the examples, 4 parts of N,N'-ethylene bis-stearamide, 2 parts of 2-(2'-hydroxy-3',5'-di-tert-pentylphenyl)benzotriazole, and 1 part of bis(2,4-di-tert-butylphenol) pentaerythritol diphosphite are mixed in a high-speed mixer for 30 min, and then extruded and granulated using a twin-screw extruder. The extruded granules are dried in a drying tower at 80℃ for 1 h, and the moisture content of the granules is measured to be less than 0.1%. The dried granules are then processed into an adhesive film with a thickness of 0.05 mm using a casting film forming machine. The casting extrusion temperature is 155℃, and the screw speed is 160 RPM / min. The evaluation results are shown in Table 1.

[0198]

[0199] According to Examples 1-8, the thermoplastic polyurethane elastomer provided by the present invention has a grain size D1 of 3-12 nm at 300% strain as measured by wide-angle X-ray diffraction (WAXD), and a grain size D2 < 1 nm after unloading. This results in a polyurethane hot melt adhesive film obtained by blending and extruding it with other functional additives under certain process conditions, which has high resilience, low activation temperature, and resistance to yellowing.

[0200] According to Comparative Examples 1 to 3, D1 and D2 of the thermoplastic polyurethane elastomers are not within the scope of the present invention, resulting in the polyurethane hot melt adhesive film having general resilience, high activation temperature, and poor resistance to yellowing.

[0201] According to Comparative Example 4, only D1 of the thermoplastic polyurethane elastomers falls within the scope of this invention. Although the polyurethane hot melt adhesive film prepared has good resilience and yellowing resistance, the activation temperature is too high.

[0202] According to Comparative Example 5, only D2 of the thermoplastic polyurethane elastomers falls within the scope of this invention. Although the polyurethane hot melt adhesive film prepared has a lower activation temperature and better yellowing resistance, its resilience is poor.

[0203] The applicant declares that this invention illustrates the thermoplastic polyurethane elastomer, polyurethane hot melt adhesive film, its preparation method, and applications through the above embodiments. However, this invention is not limited to the above embodiments, meaning that this invention does not necessarily rely on the above embodiments for implementation. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of raw materials, additions of auxiliary components, and selection of specific methods, etc., all fall within the protection and disclosure scope of this invention.

Claims

1. A thermoplastic polyurethane elastomer, characterized in that, The thermoplastic polyurethane elastomer, as determined by wide-angle X-ray diffraction, exhibits the following dynamic process: a) At 300% stretch: The wide-angle X-ray diffraction pattern shows diffraction peaks in the range of 2θ = 5 to 30°, and the grain size is D1 = 3 to 12 nm, preferably D1 = 5 to 10 nm. b) Unloaded recovery state: Wide-angle X-ray diffraction peak intensity attenuation, grain size D2 < 1 nm.

2. The polyurethane elastomer according to claim 1, characterized in that, The thermoplastic polyurethane elastomer is obtained by polymerization of isocyanate, polyol and optionally chain extender; Preferably, the isocyanate is one or a combination of two of 4,4'-dicyclohexylmethane diisocyanate, 1,4-cyclohexane diisocyanate, isophorone diisocyanate, phenyldimethyl diisocyanate, and cyclohexanedimethyl diisocyanate; more preferably, one or a combination of two of 4,4'-dicyclohexylmethane diisocyanate and 1,4-cyclohexane diisocyanate. The polyols include any one or a combination of at least two of polycarboxylate polyols, polyether polyols, polycarbonate polyols, and polycaprolactone polyols. Preferably, the number-average molecular weight (Mn) of the polyol is 1000–4000 g / mol; Preferably, the chain extender comprises any one or a combination of at least two of 1,2-ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, cyclohexanediol, hydroquinone dihydroxyethyl ether, propylenediamine, butanediamine, p-phenylenediamine, biphenyldiamine, and 3,3'-dimethyl-4,4-biphenyldiamine; more preferably, any one or a combination of at least two of 1,2-ethylene glycol, 1,3-propanediol, and 1,4-butanediol.

3. The polyurethane elastomer according to claim 1 or 2, characterized in that, The molar amount of NCO groups in the isocyanate is denoted as n1, and the total molar amount of active hydrogen groups in the polyol and chain extender is denoted as n2. The ratio of n1 to n2 is 1:(0.85-1.2), preferably 1:(0.95-1.1). Preferably, based on the total mass of the isocyanate, polyol and chain extender as 100%, the mass of the isocyanate is 10% to 30%, more preferably 12% to 25%; Preferably, based on the total mass of the isocyanate, polyol and chain extender as 100%, the mass of the chain extender is 1% to 10%, more preferably 2% to 7%; Preferably, the polymerization reaction is carried out in the presence of a catalyst; Preferably, the catalyst comprises any one or a combination of at least two of organotin catalysts, organobismuth catalysts, organozinc catalysts, organotitanium catalysts, and amine catalysts; more preferably, it comprises any one or a combination of at least two of stannous octoate, dibutyltin dilaurate, bismuth neodecanoate, zinc neodecanoate, bismuth isooctanoate, zinc isooctanoate, tetraisopropyl titanate, tetrabutyl titanate, and triethylamine. Preferably, the mass of the catalyst is 0.001% to 0.3% based on 100% of the polyol, more preferably 0.005% to 0.2%; Preferably, the polymerization reaction is carried out using processes including but not limited to extrusion or belt polymerization.

4. The polyurethane elastomer according to claim 3, characterized in that, The extrusion process includes the following steps: (a) Raw material mixing: The diisocyanate, polyol, chain extender and optional catalyst are mixed in one step according to the formulation ratio; (b) Reactive extrusion granulation: The mixture is reactively extruded and granulated using a twin-screw extruder to obtain thermoplastic polyurethane granules; (c) Continuous temperature-controlled curing: The thermoplastic polyurethane particles obtained in step (b) are continuously passed through three or more independently temperature-controlled hoppers. Preferably, the extruder control parameters include: Screw speed: 100-250 RPM, preferably 120-200 RPM / min; Extrusion temperature: 100~240℃, preferably 150~220℃; optional hot material temperature: 160~220℃, preferably 180~200℃; granulation cooling water temperature: 5~30℃, preferably 10~20℃; Preferably, the silo temperature is 20–120°C, more preferably 30–100°C; the total residence time is 4–100 h, more preferably 8–80 h.

5. The polyurethane elastomer according to claim 3, characterized in that, The belt conveyor process includes the following steps: (1) Static mixing: The diisocyanate, polyol, chain extender and optional catalyst are injected into a static mixer according to the formula ratio, and the temperature is controlled at 40-200℃, preferably 60-180℃. (2) Steel strip feeding: The mixture is conveyed to the feed end of the constant temperature steel strip; (3) Zoned polymerization: The material passes through the following zones in sequence on the steel belt: - Polymerization zone: Temperature Tpolymerization = 60-180℃, preferably 80-160℃; - Deviation zone: Temperature Tdeviation = 80–200℃, preferably 100–180℃; -Cooling zone: Temperature T_cooling = 20~60℃, preferably 20~40℃; Preferably, the running speed of the steel belt is 0.2–3 m / min, more preferably 0.5–2.5 m / min; Preferably, the total running time of the steel strip is 40–200 min, more preferably 60–180 min; (4) Low temperature cutting: The cooled thermoplastic polyurethane sheet is cut and granulated in a liquid nitrogen atmosphere.

6. The polyurethane elastomer according to any one of claims 1-5, characterized in that, The thermoplastic polyurethane elastomer has a Shore hardness of 50A to 80A, preferably 55A to 75A; Preferably, the thermoplastic polyurethane elastomer has a melting temperature of 100–140°C, more preferably 110–130°C.

7. A polyurethane hot melt adhesive film, said polyurethane hot melt adhesive film being obtained by casting extrusion of a thermoplastic polyurethane elastomer according to any one of claims 1-7.

8. The hot melt adhesive film according to claim 8, characterized in that, The preparation process of the polyurethane hot melt adhesive film includes the following steps: thermoplastic polyurethane elastomer and functional additives are mixed evenly, the mixed material is added to the feeding device of a single screw or twin screw extruder, and the film is formed by casting film forming mechanism. Preferably, the casting extrusion temperature is 100–200°C, more preferably 120–180°C, and the screw speed is 100–200 RPM / min, more preferably 120–180 RPM / min; Preferably, the film thickness is 0.03-0.2 mm; Preferably, the functional additives include one or more combinations of lubricants and anti-aging additives; Preferably, the amount of the functional additives added accounts for 0.3-7% of the thermoplastic polyurethane elastomer particles, more preferably 0.5-5%. Preferably, the lubricant is one or more of Fischer-Tropsch wax, montmorillonite wax, polyethylene wax, and N,N'-ethylene bis-stearamide, with polyethylene wax and N,N'-ethylene bis-stearamide being more preferred. Preferably, the anti-aging additive is a combination of benzotriazole light stabilizer and phosphite antioxidant, wherein the mass ratio of benzotriazole light stabilizer to phosphite antioxidant is 1-4:1, preferably 2-3:1; Preferably, the polyurethane hot melt adhesive film has a 300% resilience of ≥90%, more preferably ≥92%; Preferably, the activation temperature of the polyurethane hot melt adhesive film is 100-145°C, more preferably 115-140°C; Preferably, the polyurethane hot melt adhesive film has a yellowing resistance rating of ≥4.0 over 7*24h, and more preferably ≥4.

5.

9. The application of the polyurethane hot melt adhesive film according to claim 7 or 8, wherein the polyurethane hot melt adhesive film is suitable for the bonding layer of flexible substrates, and is particularly suitable for the bonding layer of clothing substrates, underwear substrates, shoe upper substrates, and medical dressing substrates.

10. The application of the polyurethane hot melt adhesive film according to claim 7 or 8, wherein the polyurethane hot melt adhesive film is suitable for the functional layer of a humanoid robot: Preferably, the polyurethane hot melt adhesive film serves as a functional layer at any of the following locations on the humanoid robot: (A) Epidermal covering layer; (B) The flexible substrate of electronic skin; (C) A flexible actuation layer having biomimetic muscle function.

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