Single-component reactive polyurethane hot melt adhesive as well as preparation method and application thereof

Abstract

The invention provides a single-component reactive polyurethane hot melt adhesive as well as a preparation method and application thereof, and the hot melt adhesive is prepared from the following components in parts by weight: 10 to 30 parts of polyether polyol, 20 to 30 parts of hydroxyl-terminated polybutadiene, 10 to 40 parts of crystalline polyester polyol, 5 to 20 parts of polyacrylate, 10 to 30 parts of plasticizer, 5 to 15 parts of diisocyanate, 0 to 1 part of antioxidant and 0 to 1 part of phosphoric acid. 0.1-1 part of a catalyst and 0-1 part of a coupling agent; wherein the molecular weight of the polyether polyol is 6000 to 15000, and the functionality of the polyether polyol is 3; the molecular weight of the hydroxyl-terminated polybutadiene is 2000-8000, and the functionality of the hydroxyl-terminated polybutadiene is 2-3; the molecular weight of the polyacrylate is 5000-100000, and the glass transition temperature of the polyacrylate is-20 DEG C to 20 DEG C. The prepared hot melt adhesive has the characteristics of low modulus and high bonding strength, and can be repaired.

Description

Technical Field

[0001] This invention belongs to the field of polyurethane adhesive technology, specifically relating to a single-component reactive polyurethane hot melt adhesive, its preparation method, and its application. Background Technology

[0002] One-component reactive polyurethane hot melt adhesives are widely used in consumer electronics, automotive electronics, industrial automation, and the Internet of Things (IoT). The continuous upgrading of consumer electronics products, especially the miniaturization and high-performance trends in devices such as smartphones and tablets, as well as the widespread adoption of autonomous driving technology and electric vehicles in the automotive electronics field, have all driven the growth in demand for one-component reactive polyurethane hot melt adhesives.

[0003] In the electronics industry, with structural and performance upgrades, higher demands are being placed on adhesive performance. In some applications, such as screen backing support, Type-C charging port sealing, internal filling and sealing of smart earphones, and sealing bonding of mobile phone cavities, there is an increasing need for an adhesive with low modulus, high bond strength, and easy repairability. While traditional one-component reactive polyurethane hot melt adhesives offer advantages such as high bond strength, they suffer from high modulus and lack of repairability. Therefore, how to significantly reduce the modulus while maintaining high bond strength and achieving repairability is a pressing issue that needs to be addressed. Summary of the Invention

[0004] In view of this, the present invention provides a single-component reactive polyurethane hot melt adhesive and its preparation method, which has the characteristics of low modulus and high adhesive strength, and can be repaired.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A one-component reactive polyurethane hot melt adhesive comprises the following components by weight: 10-30 parts of polyether polyol, 20-30 parts of hydroxyl-terminated polybutadiene, 10-40 parts of crystalline polyester polyol, 5-20 parts of polyacrylate, 10-30 parts of plasticizer, 5-15 parts of diisocyanate, 0-1 part of antioxidant, 0-1 part of phosphoric acid, 0.1-1 part of catalyst, and 0-1 part of coupling agent; The polyether polyol has a molecular weight of 6000~15000 and a functionality of 3. The hydroxyl-terminated polybutadiene has a molecular weight of 2000-8000 and a functionality of 2-3. The polyacrylate has a molecular weight of 5,000 to 100,000 and a glass transition temperature of -20 to 20°C.

[0006] Furthermore, the crystalline polyester polyol has a molecular weight of 2000~10000 and a functionality of 2.

[0007] Furthermore, the plasticizer is selected from one or more of dioctyl phthalate, dibutyl phthalate, diisononyl phthalate, dimethyl adipate, dioctyl adipate, dibutyl sebacate, dioctyl sebacate, tricresyl phosphate, and trioctyl phosphate.

[0008] Furthermore, the diisocyanate is selected from MDI-100 or liquefied MDI.

[0009] In some specific embodiments, preferably, the antioxidant is antioxidant 1010.

[0010] In some specific embodiments, the catalyst is preferably DMDEE.

[0011] Furthermore, the coupling agent is KH550, KH560, or KH590.

[0012] The preparation method of the above-mentioned one-component reactive polyurethane hot melt adhesive includes the following steps: Polyether polyol, hydroxyl-terminated polybutadiene, crystalline polyester polyol, polyacrylate, plasticizer, antioxidant, and phosphoric acid are added to a reaction vessel and stirred and heated to 120-150°C. Vacuum dehydration is then carried out for 60-120 minutes under stirring. The temperature is then lowered to 70-90°C, and after nitrogen depressurization, diisocyanate is added. The mixture is then stirred under vacuum and heated to 90-120°C for another 60-120 minutes. Nitrogen depressurization is then carried out, and catalyst and coupling agent are added. Vacuum stirring continues for another 30-60 minutes. Finally, after nitrogen depressurization, the mixture is discharged to obtain the final product.

[0013] The above-mentioned single-component reactive polyurethane hot melt adhesive is used in the assembly of electronic products.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: The single-component reactive polyurethane hot melt adhesive provided by this invention has a modulus ≤10 MPa at room temperature (25°C); at room temperature (25°C), the shear strength of ink glass (TP) bonded to 6013 Al alloy is ≥8 MPa, and the butt joint strength is ≥6 MPa; at room temperature (25°C), the shear strength of ink glass (TP) bonded to polycarbonate (PC) + glass fiber (GF) is ≥15 MPa, and the butt joint strength is ≥10 MPa; at a lower temperature of 60~80°C, it can be repaired, can peel off the substrate, and leaves no adhesive residue; it has the characteristics of low modulus, high bonding strength, and repairability. Detailed Implementation

[0015] The present invention will be further described in detail below with reference to specific embodiments, so that those skilled in the art can more clearly understand the present invention. Unless otherwise specified, the technical means used in the following embodiments are all conventional means well known to those skilled in the art, and all reagents and consumables are commercially available products.

[0016] Example 1 This embodiment provides a one-component reactive polyurethane hot melt adhesive, which is composed of the following components in parts by weight:

[0017] The preparation method of single-component reactive polyurethane hot melt adhesive is as follows: First, add the polyether polyol, hydroxyl-terminated polybutadiene, crystalline polyester polyol, polyacrylate, plasticizer, antioxidant, and phosphoric acid from the table above into a reaction vessel, stir and heat to 130°C, and dehydrate under vacuum for 90 minutes under stirring to obtain mixture I. Then, the mixture I was cooled to 80°C, and after the nitrogen pressure was released, diisocyanate was added. The mixture was then stirred under vacuum and heated to 100°C to continue the reaction for 90 minutes. After the nitrogen pressure was released, mixture II was obtained. Finally, the catalyst and coupling agent are added to mixture II, and the mixture is stirred under vacuum for 40 minutes. After the nitrogen pressure is released, the mixture is discharged to obtain a one-component reactive polyurethane hot melt adhesive.

[0018] Example 2 This embodiment provides a one-component reactive polyurethane hot melt adhesive, which is composed of the following components in parts by weight:

[0019] The preparation method of single-component reactive polyurethane hot melt adhesive is as follows: First, add the polyether polyol, hydroxyl-terminated polybutadiene, crystalline polyester polyol, polyacrylate, plasticizer, antioxidant, and phosphoric acid from the table above into a reaction vessel, stir and heat to 120°C, and dehydrate under vacuum for 60 minutes under stirring to obtain mixture I. Then, the mixture I was cooled to 70°C, and after the nitrogen pressure was released, diisocyanate was added. The mixture was then stirred under vacuum and heated to 90°C to continue the reaction for 60 minutes. After the nitrogen pressure was released, mixture II was obtained. Finally, the catalyst and coupling agent are added to mixture II, and the mixture is stirred under vacuum for 30 minutes. After the nitrogen pressure is released, the mixture is discharged to obtain a one-component reactive polyurethane hot melt adhesive.

[0020] Example 3 This embodiment provides a one-component reactive polyurethane hot melt adhesive, which is composed of the following components in parts by weight:

[0021] The preparation method of single-component reactive polyurethane hot melt adhesive is as follows: First, the above-mentioned polyether polyol, hydroxyl-terminated polybutadiene, crystalline polyester polyol, polyacrylate, and plasticizer are added to the reaction vessel, stirred and heated to 150°C, and vacuum dehydrated for 120 minutes under stirring to obtain mixture I. Then, the mixture I was cooled to 90°C, and after the nitrogen pressure was released, the above-mentioned diisocyanate was added. The mixture was then stirred under vacuum and heated to 120°C to continue the reaction for 120 minutes. After the nitrogen pressure was released, the mixture II was obtained. Finally, the catalyst was added to mixture II, and the mixture was stirred under vacuum for 60 minutes. After the nitrogen pressure was released, the mixture was discharged to obtain a one-component reactive polyurethane hot melt adhesive.

[0022] Comparative Example 1 This comparative example provides a single-component reactive polyurethane hot melt adhesive, whose components and preparation method are basically the same as those in Example 1, except that the molecular weight of the polyether polyol is 2000 and the functionality is 2, while the rest remain unchanged.

[0023] Comparative Example 2 This comparative example provides a single-component reactive polyurethane hot melt adhesive, whose composition and preparation method are basically the same as those in Example 1, except that hydroxyl-terminated polybutadiene is not added, while the rest remain unchanged.

[0024] Comparative Example 3 This comparative example provides a single-component reactive polyurethane hot melt adhesive, whose composition and preparation method are basically the same as those in Example 1, except that no plasticizer is added, while all other aspects remain unchanged.

[0025] Comparative Example 4 This comparative example provides a single-component reactive polyurethane hot melt adhesive, whose components and preparation method are basically the same as those in Example 1, except that the hydroxyl-terminated polybutadiene is changed to 5 parts, while the rest remain unchanged.

[0026] Comparative Example 5 This comparative example provides a one-component reactive polyurethane hot melt adhesive, whose composition and preparation method are basically the same as those in Example 1, except that the molecular weight of the polyacrylate is 30,000 and the glass transition temperature is 60°C.

[0027] Performance Tests and Results The performance of the single-component reactive polyurethane hot melt adhesives of Examples 1-3 and Comparative Examples 1-5 was tested respectively, and the performance test results of each hot melt adhesive are shown in Table 1.

[0028] Table 1. Test results of various hot melt adhesives

[0029] As shown in Table 1, the single-component reactive polyurethane hot melt adhesives of Examples 1-3 have a modulus ≤10 MPa at room temperature (25°C); at room temperature (25°C), the shear strength of ink glass (TP) bonded to metal 6013 Al alloy is ≥8 MPa, and the butt joint strength is ≥6 MPa; at room temperature (25°C), the shear strength of ink glass (TP) bonded to polycarbonate (PC) + glass fiber (GF) is ≥15 MPa, and the butt joint strength is ≥10 MPa; at a lower temperature of 60-80°C, rework can be achieved, the substrate can be peeled off, and no adhesive residue is left.

[0030] Compared to Comparative Examples 1-5, the single-component reactive polyurethane hot melt adhesives of Examples 1-3 simultaneously possess the characteristics of low modulus, high bond strength, and reworkability. This invention significantly improves bond strength by introducing high molecular weight, high-functionality polyether polyols and hydroxyl-terminated polybutadiene; while the introduction of polyacrylates with low glass transition temperatures and plasticizers effectively reduces modulus. Finally, through compounding and exploration, a hot melt adhesive formulation that can significantly reduce modulus while improving bond strength was obtained, enabling rework when applied to the bonding of electronic product assemblies.

[0031] Unless otherwise specified, all raw materials used in this invention are existing substances that can be purchased directly from the market.

[0032] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A one-component reactive polyurethane hot melt adhesive, characterized in that, The product comprises the following components by weight: 10-30 parts of polyether polyol, 20-30 parts of hydroxyl-terminated polybutadiene, 10-40 parts of crystalline polyester polyol, 5-20 parts of polyacrylate, 10-30 parts of plasticizer, 5-15 parts of diisocyanate, 0-1 part of antioxidant, 0-1 part of phosphoric acid, 0.1-1 part of catalyst, and 0-1 part of coupling agent. The polyether polyol has a molecular weight of 6000~15000 and a functionality of 3. The hydroxyl-terminated polybutadiene has a molecular weight of 2000-8000 and a functionality of 2-3. The polyacrylate has a molecular weight of 5,000 to 100,000 and a glass transition temperature of -20 to 20°C.

2. The single-component reactive polyurethane hot melt adhesive according to claim 1, characterized in that, The crystalline polyester polyol has a molecular weight of 2000~10000 and a functionality of 2.

3. The single-component reactive polyurethane hot melt adhesive according to claim 1, characterized in that, The plasticizer is selected from one or more of dioctyl phthalate, dibutyl phthalate, diisononyl phthalate, dimethyl adipate, dioctyl adipate, dibutyl sebacate, dioctyl sebacate, tricresyl phosphate, and trioctyl phosphate.

4. The single-component reactive polyurethane hot melt adhesive according to claim 1, characterized in that, The diisocyanate is selected from MDI-100 or liquefied MDI.

5. The single-component reactive polyurethane hot melt adhesive according to claim 1, characterized in that, The antioxidant is antioxidant 1010.

6. The single-component reactive polyurethane hot melt adhesive according to claim 1, characterized in that, The catalyst is DMDEE.

7. The single-component reactive polyurethane hot melt adhesive according to claim 1, characterized in that, The coupling agent is KH550, KH560 or KH590.

8. A method for preparing a single-component reactive polyurethane hot melt adhesive according to any one of claims 1-7, characterized in that, Includes the following steps: Polyether polyol, hydroxyl-terminated polybutadiene, crystalline polyester polyol, polyacrylate, plasticizer, antioxidant, and phosphoric acid are added to a reaction vessel and stirred and heated to 120-150°C. Vacuum dehydration is then carried out for 60-120 minutes under stirring. The temperature is then lowered to 70-90°C, and after nitrogen depressurization, diisocyanate is added. The mixture is then stirred under vacuum and heated to 90-120°C for another 60-120 minutes. Nitrogen depressurization is then carried out, and catalyst and coupling agent are added. Vacuum stirring continues for another 30-60 minutes. Finally, after nitrogen depressurization, the mixture is discharged to obtain the final product.

9. The application of the single-component reactive polyurethane hot melt adhesive according to any one of claims 1-7 in the assembly of electronic products.

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