Highly adhesive and highly supporting polyurethane shoe glue and preparation method thereof

Abstract

The present application belongs to the technical field of polyurethane adhesive, and particularly relates to a high-adhesion and high-support polyurethane shoe adhesive and a preparation method thereof. The shoe adhesive is prepared from component A and component B at a mass ratio of 100: (20-45), wherein component A is composed of the following raw materials in mass percentage: polyether polyol 1: 5-20%; polyether polyol 2: 57.48-84.52%; plasticizer: 10-20%; anti-aging agent: 0.4-2.5%; and catalyst: 0.02-0.08%; and component B is composed of the following raw materials in mass percentage: polyether polyol 3: 15.8-41.6%; polyether polyol 4: 18.3-33.1%; dipropylene glycol: 1.2-6.2%; and diisocyanate: 38.9-48.7%. The shoe adhesive has high initial adhesion strength, good adhesion, long-term stability and excellent mechanical properties. The present application also provides a preparation method thereof.

Description

Technical Field

[0001] This invention belongs to the field of polyurethane adhesive technology, specifically relating to a high-adhesion, high-support polyurethane shoe adhesive and its preparation method. Background Technology

[0002] Polyurethane (PU) adhesives are key materials widely used in the footwear industry. Their molecular backbone is formed through microphase separation of flexible soft segments (such as polyester and polyether polyols) and rigid hard segments (such as diisocyanates and chain extenders), resulting in excellent elasticity, abrasion resistance, and low-temperature resistance. An ideal polyurethane heel pad adhesive must form a strong bond with substrates such as sole rubber, EVA, TPU, leather, and fiber fabrics. After curing, it must also possess excellent mechanical properties, including sufficient strength, hardness, and toughness to withstand complex dynamic bending, friction, and impact loads during wear. However, traditional polyurethane footwear adhesives struggle to simultaneously achieve both adhesive and cohesive properties. Increasing the content of polar groups to improve initial and final tack strength reduces the strength and hardness of the adhesive film itself; conversely, excessively strengthening cohesive strength makes the adhesive brittle and less flexible, weakening its wetting and penetration ability into the shoe material, ultimately leading to a decline in bonding effectiveness.

[0003] In existing technologies, common methods for improving the performance of polyurethane adhesives include blending modification, adding nanofillers, or using polyols with special structures. For example, adding silane coupling agents can improve adhesion to inorganic materials, or blending with chloroprene rubber (CR) can improve initial tack. However, physical blending can easily lead to poor compatibility and system instability; while excessive addition of rigid inorganic fillers (such as silica and calcium carbonate) can improve hardness and strength, it can significantly reduce the flexibility and transparency of the adhesive and may induce interfacial damage due to stress concentration. Furthermore, these modification methods often focus on improving a single property, making it difficult to achieve synergistic optimization between adhesive performance and the cohesive strength and hardness of the adhesive.

[0004] Chinese patent CN1796481A discloses a polyurethane adhesive for footwear and its preparation method. The polyurethane adhesive, by weight, comprises: 15-18% polyurethane elastomer, 78-82% organic solvent, and 1-3% inorganic ultrafine powder. The polyurethane elastomer is prepared from polyester polyol, polyether polyol, chain extender, isocyanate, and inorganic nanoparticles. However, the high proportion of organic solvent (78-82%) in this patent formulation presents a problem of volatility; simultaneously, the addition of inorganic ultrafine powder reduces the transparency of the product, resulting in a hazy appearance. This solution only focuses on the bonding effect of the shoe material, neglecting the strength, hardness, and toughness of the product, which are crucial factors affecting wearing comfort.

[0005] Therefore, developing a high-performance polyurethane shoe adhesive for preparing polyurethane shoe heel pads, while simultaneously and significantly improving the cohesive strength, hardness, and durability of the cured adhesive without sacrificing its excellent flexibility and adhesion properties, is of great significance for meeting the comprehensive performance requirements of high-end footwear products and extending product lifespan. This is also a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the purpose of this invention is to provide a high-adhesion, high-support polyurethane shoe adhesive with high initial bond strength, good adhesion and long-term stability, and excellent mechanical properties. This invention also provides its preparation method, which has a fast molding speed, moderate working time, and is convenient for industrial mass production.

[0007] The objective of this invention is achieved through the following technical solution: The aforementioned high-adhesion, high-support polyurethane shoe adhesive is made from component A and component B in a mass ratio of 100:(20-45), wherein component A consists of the following raw materials in mass percentage: Polyether polyol 1:5-20%; Polyether polyol 2: 57.48–84.52%; Plasticizer: 10-20%; Anti-aging agent: 0.4–2.5%; Catalyst: 0.02–0.08%; Component B consists of the following raw materials by mass percentage: Polyether polyol 3: 15.8–41.6%; Polyether polyol 4: 18.3–33.1%; Dipropylene glycol: 1.2–6.2%; Diisocyanate: 38.9%–48.7%; The polyether polyol 1 has a number-average molecular weight of 200-800 and a functionality of 3-4. The polyether polyol 2 has a number-average molecular weight of 4000-6000 and a functionality of 3-4. The number-average molecular weight of the plasticizer is 100-400; The polyether polyol 3 has a number-average molecular weight of 2800-5000 and a functionality of 2-3. The polyether polyol 4 has a number-average molecular weight of 300-1800 and a functionality of 2-3.

[0008] Preferably, the polyether polyol 1 is DV-125N.

[0009] Preferably, the polyether polyol 2 is EP-76E or EP-83E.

[0010] Preferably, the plasticizer is ZA or ZC.

[0011] Preferably, the polyether polyol 3 is DL-4000D.

[0012] Preferably, the polyether polyol 4 is DL-1000D.

[0013] The anti-aging agent mentioned is antioxidant P838.

[0014] The catalyst is a bismuth-based catalyst.

[0015] The diisocyanate is an MDI-type isocyanate, preferably a mixture of MDI-100 and CD-C.

[0016] The preparation method of the high-adhesion, high-support polyurethane shoe adhesive of the present invention includes the following steps: (1) Preparation of component A: Polyether polyol 1, plasticizer and polyether polyol 2 are mixed and dehydrated until the moisture content is not higher than 0.05wt%. Then, the mixture is cooled, and anti-aging agent and catalyst are added and stirred evenly to obtain component A. (2) Preparation of component B: Polyether polyol 3, polyether polyol 4, dipropylene glycol and diisocyanate are mixed and reacted until the -NCO content is 9-10 wt% to obtain component B; (3) Molding: Mix component A and component B evenly, pour the mixture onto the shoe material to be bonded, and heat and cure it in an oven to obtain the high-adhesion and high-support polyurethane shoe adhesive.

[0017] The cooling temperature in step (1) is 60-70℃.

[0018] The reaction temperature in step (2) is 80-90℃.

[0019] In step (3), the oven curing temperature is 85-100℃ and the curing time is 3 minutes.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The high-adhesion, high-support polyurethane shoe adhesive of the present invention significantly improves the adhesive performance by introducing dipropylene glycol into the molecular structure, without significantly affecting the strength, toughness, and resilience of the polyurethane shoe adhesive. Dipropylene glycol (DPG) can participate in the polyurethane polymerization reaction. The propyl ether segment in its molecule is highly hydrophobic and has low surface energy, which can moderately adjust the surface tension of the adhesive, making the adhesive easier to spread and wet on the substrate surface, increasing the contact area, and thus improving the adhesive performance.

[0021] (2) As a reactive component, DPG molecules can be anchored in the polyurethane crosslinking network through chemical bonds. It can form a strong interaction with the free non-reactive plasticizer in the system, effectively fix the plasticizer, greatly inhibit plasticizer migration, and ensure the long-term stability of the adhesive bonding performance.

[0022] (3) This invention produces a highly adhesive and supportive polyurethane shoe adhesive through a specific raw material formulation and preparation process, which has excellent mechanical properties. The adhesive has moderate strength, hardness and toughness, and can withstand repeated bending, friction and impact loads generated during the use of the shoe body.

[0023] (4) The high-adhesion and high-support polyurethane shoe adhesive prepared by the present invention has a high initial adhesive strength. After the product is placed at room temperature for 7 days, the 180° peel force of the optimal formulation sample can reach more than 2000gf.

[0024] (5) This preparation method has a fast molding speed, suitable operation time, strong process controllability, and is easy to industrial mass production. Detailed Implementation

[0025] The present invention will be further described below with reference to the embodiments and comparative examples. Unless otherwise specified, the raw materials used in the embodiments and comparative examples are all conventional commercial raw materials, and the process methods used are all conventional methods in the art unless otherwise specified.

[0026] DV-125N, with a functionality of 3 and a number-average molecular weight of 375, was purchased from Lanxing Dongda Chemical Co., Ltd. ZA, plasticizer, purchased from Jurong Ningwu New Materials Co., Ltd.; ZC, plasticizer, purchased from Lanxing Dongda Chemical Co., Ltd.; EP-76E, with a functionality of 3 and a number-average molecular weight of 4800, was purchased from Lanxing Dongda Chemical Co., Ltd. EP-83E, with a functionality of 3 and a number-average molecular weight of 6000, was purchased from Lanxing Dongda Chemical Co., Ltd. DL-1000D, with a functionality of 2 and a number-average molecular weight of 1000, was purchased from Lanxing Dongda Chemical Co., Ltd. DL-4000D, with a functionality of 2 and a number-average molecular weight of 4000, was purchased from Lanxing Dongda Chemical Co., Ltd. MDI-100 was purchased from Wanhua Chemical Group Co., Ltd. CD-C is carbodiimide-modified MDI, purchased from Bayer Group, Germany; Dipropylene glycol (DPG), with a number-average molecular weight of 134, was purchased from Shandong Yaojia Chemical Co., Ltd. Antioxidant P838, purchased from BASF Group, Germany; BiCAT organic bismuth catalyst ® 085, purchased from a leading American chemical company.

[0027] Example 1 The high-adhesion, high-support polyurethane shoe adhesive described in this embodiment is made from component A and component B in a mass ratio of 100:20, wherein... Component A consists of the following raw materials by mass percentage: DV-125N: 5%; EP-83E: 84.52%; ZC: 10%; Antioxidant P838: 0.4%; BiCAT ® 085: 0.08%; Component B consists of the following raw materials by mass percentage: DL-4000D: 41.6%; DL-1000D: 18.3%; Dipropylene glycol (DPG): 1.2%; MDI-100: 23.3%; CD-C: 15.6%.

[0028] The high-adhesion, high-support polyurethane shoe adhesive is prepared by the following method: (1) Preparation of component A: DV-125N, ZC and EP-83E were mixed, heated to 105.5±3℃, and dehydrated under a vacuum of -0.095MPa until the water content was ≤0.05wt%. Then cooled to 60±3℃, antioxidant P838 and catalyst BiCAT were added. ® 085, stir thoroughly until homogeneous to obtain component A; (2) Preparation of component B: DL-4000D, DL-1000D, DPG, MDI-100 and CD-C were reacted at 85±5℃ for 4 h. After the reaction, the bubbles in the system were removed under a vacuum of -0.095 MPa to obtain component B, whose -NCO content was determined to be 9 wt%. (3) Molding and curing: Mix component A and component B evenly at a set mass ratio in an environment of 32.5±2.5℃, immediately pour into the surface of the shoe sole substrate, and then place in an oven at 95℃ for curing for 3 minutes to finally obtain the high-adhesion and high-support polyurethane shoe adhesive.

[0029] Example 2 The high-adhesion, high-support polyurethane shoe adhesive described in this embodiment is made of component A and component B in a mass ratio of 100:32, wherein... Component A consists of the following raw materials by mass percentage: DV-125N: 12%; EP-76E: 71.54%; ZA: 15%; Antioxidant P838: 1.4%; BiCAT ® 085: 0.06%; Component B consists of the following raw materials by mass percentage: DL-4000D: 15.8%; DL-1000D: 33.1%; Dipropylene glycol (DPG): 4.2%; MDI-100: 28.2%; CD-C: 18.7%.

[0030] The high-adhesion, high-support polyurethane shoe adhesive is prepared by the following method: (1) Preparation of component A: DV-125N, ZA and EP-76E were mixed, heated to 105.5±3℃, vacuumed to -0.095MPa, dehydrated to a moisture content ≤0.05wt%, then cooled to 60±3℃, and antioxidant P838 and BiCAT were added. ® 085, stir evenly to obtain component A; (2) Preparation of component B: DL-4000D, DL-1000D, DPG, MDI-100 and CD-C were mixed and reacted at 85±5℃ for 4h. After the reaction was completed, the vacuum was evacuated to -0.095MPa to remove bubbles, and component B was obtained. Its -NCO content was measured to be 9.5wt%. (3) Mix components A and B evenly at 32.5±2.5℃ according to the mass ratio, quickly pour the mixture onto the shoe sole substrate, place it in an oven at 90℃, and cure for 3 minutes to obtain a high-adhesion and high-support polyurethane shoe adhesive.

[0031] Example 3 The high-adhesion, high-support polyurethane shoe adhesive described in this embodiment is made of component A and component B in a mass ratio of 100:45, wherein... Component A consists of the following raw materials by mass percentage: DV-125N: 20%; EP-76E: 57.48%; ZC: 20%; Antioxidant P838: 2.5%; BiCAT ® 085: 0.02%; Component B consists of the following raw materials by mass percentage: DL-4000D: 20.5%; DL-1000D: 24.6%; Dipropylene glycol (DPG): 6.2%; MDI-100: 29.2%; CD-C: 19.5%.

[0032] The high-adhesion, high-support polyurethane shoe adhesive is prepared by the following method: (1) Preparation of component A: DV-125N, ZC and EP-76E were mixed, heated to 105.5±3℃, and dehydrated under a vacuum of -0.095MPa until the water content was ≤0.05wt%. Then cooled to 60±3℃, antioxidant P838 and catalyst BiCAT were added. ® 085, stir thoroughly until homogeneous to obtain component A; (2) Preparation of component B: DL-4000D, DL-1000D, DPG, MDI-100 and CD-C were reacted at 85±5℃ for 4 h. After the reaction, the bubbles in the system were removed under a vacuum of -0.095 MPa to obtain component B, whose -NCO content was determined to be 10 wt%. (3) Molding and curing: Mix component A and component B evenly at a set mass ratio in an environment of 32.5±2.5℃, immediately pour into the surface of the shoe sole substrate, and then place in an oven at 100℃ for curing for 3 minutes to finally obtain the high-adhesion and high-support polyurethane shoe adhesive.

[0033] Comparative Example 1 The high-adhesion, high-support polyurethane shoe adhesive described in this comparative example is made from component A and component B in a mass ratio of 100:32, wherein... Component A consists of the following raw materials by mass percentage: DV-125N: 12%; EP-76E: 71.54%; ZA: 15%; Antioxidant P838: 1.4%; BiCAT ® 085: 0.06%; Component B consists of the following raw materials by mass percentage: DL-4000D: 15.8%; DL-1000D: 41.7%; MDI-100: 25.5%; CD-C: 17%.

[0034] The high-adhesion, high-support polyurethane shoe adhesive is prepared by the following method: (1) Preparation of component A: DV-125N, ZA and EP-76E were mixed, heated to 105.5±3℃, and dehydrated under a vacuum of -0.095MPa until the water content was ≤0.05wt%. Then cooled to 60±3℃, antioxidant P838 and catalyst BiCAT were added. ® 085, stir thoroughly until homogeneous to obtain component A; (2) Preparation of component B: DL-4000D, DL-1000D, MDI-100 and CD-C were reacted at 85±5℃ for 4 h. After the reaction, the bubbles in the system were removed under a vacuum of -0.095 MPa to obtain component B, whose -NCO content was determined to be 9.5 wt%. (3) Molding and curing: Mix component A and component B evenly at a set mass ratio in an environment of 32.5±2.5℃, immediately pour into the surface of the shoe sole substrate, and then place in an oven at 95℃ for curing for 3 minutes to finally obtain the high-adhesion and high-support polyurethane shoe adhesive.

[0035] Comparative Example 2 The shoe adhesive was purchased from JD.com, product number 10080701338871. Components A and B were mixed evenly at a mass ratio under conditions of 32.5±2.5℃, and then quickly poured onto the shoe sole substrate. The mixture was then placed in an oven at 95℃ and cured for 3 minutes to obtain a polyurethane product.

[0036] The colloids from Examples 1-3 and Comparative Examples 1-2 were placed for 7 days and then tested. The test results are shown in Table 1. The test method is as follows: 180° Peel Strength: Using a coating applicator, the mixed polyurethane components A and B are coated onto a substrate to form a 1 mm thick sheet, which is then cut into 25 mm wide rectangular samples. Peel tests are conducted according to GB / T 2791-1995.

[0037] Hardness: Tested using a Shore OO type hardness tester. The test was conducted in accordance with GB / T 39693.4-2025.

[0038] Support: This is related to the requirements of wearable products. It is usually judged by hardness. A hardness greater than 5000 is generally considered to have good support.

[0039] Tensile strength and elongation at break: Tested in accordance with GB / T 528-2009.

[0040] Table 1 Performance Test Results

[0041] Comparing Comparative Example 1 with Examples 1-3, it can be observed that the 180° peel force gradually increases with the increase of dipropylene glycol content, indicating that dipropylene glycol participates in the polymerization reaction in the polyurethane system. Analysis of the peel force reveals that the propyl ether segments of dipropylene glycol are relatively hydrophobic and have low surface energy, which can fine-tune the surface tension of the adhesive, making it easier to spread and wet the substrate, increasing the contact area and enhancing adhesion. As a reactive component, dipropylene glycol molecules are chemically anchored in the polyurethane network, allowing for stronger interactions with free non-reactive plasticizer molecules, effectively "locking in" these plasticizers, greatly reducing migration, and maintaining long-term stability of adhesive performance.

[0042] Analysis of Examples 1-3 reveals that with the increase in small molecules, the hardness of the product increases from 5200 to 6000, while the tensile strength increases and the elongation at break decreases. For polyurethane heel pads, a hardness above Shore 5000 indicates excellent support.

[0043] Comparing Examples 2-3 with Comparative Example 2, it can be found that under the same support conditions, the peel force (adhesion effect) of Examples 2-3 is better than that of commercially available products.

Claims

1. A high-adhesion, high-support polyurethane shoe adhesive, characterized in that: It is made from component A and component B in a mass ratio of 100:(20-45), wherein component A consists of the following raw materials in mass percentage: Polyether polyol 1:5-20%; Polyether polyol 2: 57.48–84.52%; Plasticizer: 10-20%; Anti-aging agent: 0.4–2.5%; Catalyst: 0.02–0.08%; Component B consists of the following raw materials by mass percentage: Polyether polyol 3: 15.8–41.6%; Polyether polyol 4: 18.3–33.1%; Dipropylene glycol: 1.2–6.2%; Diisocyanate: 38.9%–48.7%; The polyether polyol 1 has a number-average molecular weight of 200-800 and a functionality of 3-4. The polyether polyol 2 has a number-average molecular weight of 4000-6000 and a functionality of 3-4. The plasticizer has a number-average molecular weight of 100-400; the polyether polyol 3 has a number-average molecular weight of 2800-5000 and a functionality of 2-3. The polyether polyol 4 is DL-1000D.

2. The high-adhesion, high-support polyurethane shoe adhesive according to claim 1, characterized in that: The polyether polyol 1 is DV-125N.

3. The high-adhesion, high-support polyurethane shoe adhesive according to claim 1, characterized in that: The polyether polyol 2 is EP-76E or EP-83E.

4. The high-adhesion, high-support polyurethane shoe adhesive according to claim 1, characterized in that: The polyether polyol 3 is DL-4000D.

5. The high-adhesion, high-support polyurethane shoe adhesive according to claim 1, characterized in that: The catalyst is a bismuth-based catalyst.

6. The high-adhesion, high-support polyurethane shoe adhesive according to claim 1, characterized in that: The diisocyanate mentioned is an MDI-type isocyanate.

7. A method for preparing a high-adhesion, high-support polyurethane shoe adhesive according to any one of claims 1-6, characterized in that: Includes the following steps: (1) Preparation of component A: Polyether polyol 1, plasticizer and polyether polyol 2 are mixed and dehydrated until the moisture content is not higher than 0.05wt%. Then, the mixture is cooled, and anti-aging agent and catalyst are added and stirred evenly to obtain component A. (2) Preparation of component B: Polyether polyol 3, polyether polyol 4, dipropylene glycol and diisocyanate are mixed and reacted until the -NCO content is 9-10 wt% to obtain component B; (3) Molding: Mix component A and component B evenly, pour the mixture onto the shoe material to be bonded, and heat and cure it in an oven to obtain the high-adhesion and high-support polyurethane shoe adhesive.

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