A high temperature resistant polyamide hot melt adhesive and its preparation method and application

Abstract

The present invention discloses a high-temperature resistant polyamide hot melt adhesive and its preparation method and application, and belongs to the field of polyamide hot melt adhesive. The high-temperature resistant polyamide hot melt adhesive of the present invention comprises polyamide hot melt adhesive, methyl vinyl silicone rubber, vulcanizing agent, polyisobutylene, and ethylene-acrylic acid copolymer. Compatibilized silicone rubber is obtained by pre-mixing methyl vinyl silicone rubber and ethylene-acrylic acid copolymer, thereby improving the compatibility of silicone rubber in polyamide hot melt adhesive, and then the polyamide hot melt adhesive and polyisobutylene are melt-blended. A heat stabilizer and an antioxidant can also be added during the melt-blending stage, and then the above-mentioned compatibilized silicone rubber and vulcanizing agent are added in sequence. The high-temperature resistant polyamide hot melt adhesive prepared by dynamic vulcanization has high transparency, both high-temperature and low-temperature resistance, low gluing temperature, good construction performance, and is environmentally friendly, stable, and has good sealing properties. It can be applied to industries such as electronic components, automotive parts, wiring harnesses, and cables, and is particularly suitable for the field of automotive wiring harness protection.

Description

Technical Field

[0001] The present invention relates to the field of polyamide hot melt adhesives, and in particular to a high-temperature resistant polyamide hot melt adhesive and a preparation method and application thereof. Background Art

[0002] Hot melt adhesives are 100% solids, solvent-free, environmentally friendly, non-toxic, and fast-curing, making them widely applicable. Polyamide hot melt adhesives are formed through the condensation reaction of dimer acid, dibasic acid, and di- or polyamines. They exhibit excellent heat and cold resistance, electrical properties, oil resistance, and chemical resistance. They are odorless, cure quickly, and can bond a variety of metals and non-metals. They hold broad application prospects in the packaging of electronic and electrical components, automotive assembly, and cable assembly.

[0003] However, in the assembly of electronic components and automotive parts, as well as in the protection of wiring harnesses and cables, the high working environment temperature and the heat generated under working conditions can lead to thermal oxidative degradation of the material, poor heat resistance and shortened service life, which limits the application of traditional polyamide hot melt adhesives and makes it difficult for traditional hot melt adhesives to meet the application requirements of special packaging industries. Summary of the Invention

[0004] In order to solve the technical problems of the prior art as described above, the present invention provides a high-transparency, high-temperature-resistant polyamide hot melt adhesive having both high-temperature resistance and low-temperature performance, as well as a preparation method and application thereof.

[0005] To achieve the above object, the present invention provides a high-temperature resistant polyamide hot melt adhesive, which comprises the following components in parts by weight:

[0006]

[0007] Optionally, the melting point of the polyamide hot melt adhesive is 90°C-105°C.

[0008] Optionally, the vulcanizing agent includes at least one of dicumyl peroxide, benzoyl peroxide, and di-tert-butyl peroxide;

[0009]

[0010] Optionally, the heat stabilizer includes at least one of a rare earth heat stabilizer and a polyamine heat stabilizer;

[0011] Optionally, the antioxidant includes at least one of a hindered phenol antioxidant and a thioester antioxidant.

[0012] Optionally, the antioxidant is a composite antioxidant, which is compounded by a hindered phenol antioxidant and a thioester antioxidant, wherein the weight ratio of the hindered phenol antioxidant to the thioester antioxidant is 1:(0.5-3).

[0013] Further optionally, the hindered phenol antioxidant includes at least one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate (antioxidant 1010), β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate (antioxidant 1076), and triethylene glycol bis[β-(3-tert-butyl-4-hydroxy-5-methylphenyl) propionate] (antioxidant 245);

[0014] Further optionally, the thioester antioxidant includes at least one of dilauryl thiodipropionate (DLTP) and dioctadecyl thiodipropionate (DSTOP);

[0015] Optionally, the high-temperature resistant polyamide hot melt adhesive is transparent.

[0016] Optionally, the gluing temperature of the high-temperature resistant polyamide hot melt adhesive is below 105°C.

[0017] In addition, to achieve the above-mentioned object, the present invention also provides a method for preparing a high-temperature resistant polyamide hot melt adhesive, the preparation method comprising the following steps:

[0018] S10, mixing methyl vinyl silicone rubber and ethylene-acrylic acid copolymer to obtain a compatibilized silicone rubber;

[0019] S20, melt-blending a polyamide hot melt adhesive and polyisobutylene, then adding the compatibilized silicone rubber and a vulcanizing agent, and preparing the high-temperature resistant polyamide hot melt adhesive by a dynamic vulcanization method.

[0020] Optionally, in the step of melt-blending the polyamide hot melt adhesive and polyisobutylene, a heat stabilizer and an antioxidant are also added for melt-blending.

[0021] Optionally, the melt blending temperature is 120° C.-140° C., the melt blending speed is 50-70 r / min, and the melt blending time is 3-5 min.

[0022] Optionally, the temperature of the dynamic vulcanization method is 120° C.-140° C., and the rotation speed is 50-70 r / min.

[0023] The present invention also provides an application of the high-temperature resistant polyamide hot melt adhesive as described above, which can be widely used in the fields of electronic components, automotive parts, wiring harnesses and cables.

[0024] The beneficial effects that can be achieved by the present invention are:

[0025] The high-temperature resistant polyamide hot melt adhesive prepared by the present invention through a reasonably designed formula and a dynamic vulcanization method with high shear mixing means has high transparency and can meet the needs of various fields, especially automobile companies, for visualization of internal parts; the product is environmentally friendly and solvent-free, has good stability, can be stored for a long time, and there is no risk of additive precipitation; the product has both excellent high-temperature resistance and good low-temperature performance, and can be applied at low temperatures below 105°C, with good construction performance and sealing, which can save energy, meet the packaging field with high requirements on adhesive application temperature, thermal stability, and low-temperature performance, and can be widely used in electronic components, automotive parts, wiring harnesses, and cables. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0027] Figure 1 The present invention is a schematic flow chart of a method for preparing a high-temperature resistant polyamide hot melt adhesive.

[0028] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0029] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0030] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0031] In the present invention, descriptions such as "first" and "second" are for descriptive purposes only and should not be understood as indicating or implying their relative importance or implicitly indicating the number of the technical features indicated. Therefore, features defined as "first" or "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions of various embodiments may be combined with each other, but this must be based on the fact that they can be implemented by a person of ordinary skill in the art. If the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0032] In the assembly of electronic components and automotive parts, as well as in the protection of wiring harnesses and cables, the high working environment temperature and the heat generated under working conditions can lead to thermal oxidation degradation of the material, poor heat resistance and stability, and shortened service life, which limits the application of traditional polyamide hot melt adhesives and makes it difficult for traditional hot melt adhesives to meet the application requirements of special packaging industries.

[0033] Take the automotive industry, for example. With its rapid development, the demand for adhesives used in auto parts is increasing. Production lines require high levels of automation and efficiency, demanding excellent adhesive sealing and a short curing time. Furthermore, in summer, cars exposed to the sun can reach temperatures as high as 80-100°C, and the engine's surroundings can reach high temperatures during operation, placing high demands on nearby parts and components. Consequently, high heat resistance is also a requirement for adhesives. Furthermore, while car safety and driving experience are emphasized, people are also paying greater attention to interior air quality, becoming intolerant of irritating odors and prioritizing quality of life. Solvent-based automotive adhesives evaporate continuously over long periods of time, emitting unpleasant odors in the car, which can significantly impact human health.

[0034] In view of this, the present invention provides a high-temperature resistant polyamide hot melt adhesive, which comprises the following components in parts by weight:

[0035]

[0036] The high-temperature resistant polyamide hot melt adhesive of the present invention has a transparent appearance, is resistant to high and low temperatures and has good weather resistance. The gluing temperature is below 105° C., and the construction performance is good.

[0037] In some embodiments, the melting point of the polyamide hot melt adhesive is 90° C.-105° C., which can give the high-temperature resistant polyamide hot melt adhesive of the present invention a lower gluing temperature.

[0038] In some embodiments, the polyamide hot melt adhesive is a linear polyamide hot melt adhesive, which can provide good fluidity under a certain pressure.

[0039] The methyl vinyl silicone rubber used in the raw material components is colorless and transparent, has excellent electrical insulation properties, a very flexible molecular chain, and excellent cold, heat, and weather resistance. It also has a low hardness and can typically operate at -55°C and can operate for extended periods at 180°C. Methyl vinyl silicone rubber, used as a silicone rubber raw material in the preparation of the high-temperature-resistant polyamide hot-melt adhesive of the present invention, can impart excellent workability and weather resistance to the product.

[0040] The use of polyisobutylene can give high-temperature resistant polyamide hot melt adhesive extremely high adhesion, flexibility and air tightness, making it less likely to cause glue to flow due to high temperature.

[0041] In addition, ethylene-acrylic acid copolymer, as a compatibilizer, is pre-mixed, allowing its molecular chains to more easily form an entangled structure with the molecular chains of methyl vinyl silicone rubber, improving the compatibility of methyl vinyl silicone rubber in polyamide hot melt adhesives and resulting in a more stable product. Furthermore, ethylene-acrylic acid copolymer has good thermoplasticity and high adhesion, which can impart better adhesion, toughness, and processability to the product. When used in combination with polyisobutylene, it can further enhance the adhesion of high-temperature resistant polyamide hot melt adhesives, further improving the product's performance under high-temperature conditions and preventing the product from slipping due to high temperatures.

[0042] When methyl vinyl silicone rubber and polyamide hot melt adhesive are compounded, the polyamide hot melt adhesive will entangle with the molecular chains of methyl vinyl silicone rubber, especially under the action of dynamic vulcanization, which will also form a network unit structure of methyl vinyl silicone rubber. This structure can play a supporting role in the hot melt adhesive mixture. At the same time, dynamic vulcanization can also cause interfacial grafting reaction, which can limit the slip between polyamide molecular chains.

[0043] When the polyamide molecular chains in this invention's product attempt to slide due to their own weight at high temperatures, they are prevented by the aforementioned bonding forces, interfacial grafting, and the network structure of the methyl vinyl silicone rubber. The polyamide hot melt adhesive remains adhered to the methyl vinyl silicone rubber network, preventing it from flowing. Furthermore, due to its linear nature, the polyamide hot melt adhesive has few side chains and is highly flexible. With only a certain amount of pressure, it maintains adequate fluidity, enabling application at relatively low temperatures and ensuring excellent sealing performance after use.

[0044] In some embodiments, the vulcanizing agent includes at least one of dicumyl peroxide, benzoyl peroxide, and di-tert-butyl peroxide. The above types of vulcanizing agents are more conducive to improving the vulcanization effect of methyl vinyl silicone rubber. After vulcanization, the methyl vinyl silicone rubber itself will form a network unit structure, which can play a supporting role. In addition, the methyl vinyl silicone rubber and the polyamide hot melt adhesive will undergo an interfacial grafting reaction, which can greatly improve the problem of polyamide molecular chains easily flowing under high temperature conditions.

[0045] In some embodiments, in order to prevent the polyamide molecular chains from being easily broken and degraded by the thermal oxygen environment and the internal structure from being destroyed when the product is used at high temperature for a long time, the high temperature resistant polyamide hot melt adhesive of the present invention is further added with a heat stabilizer and an antioxidant. Calculated by weight, the amount of heat stabilizer added is 0.05-0.15 parts, and the amount of antioxidant added is 0.2-1 parts.

[0046] The compound use of the above-mentioned heat stabilizers and antioxidants can enhance the structural stability of the high-temperature resistant polyamide hot melt adhesive in a long-term high-temperature environment, making it less likely to cause glue dripping. At the same time, it also ensures the low-temperature operability of the glue and the sealing performance of the product after use.

[0047] The present invention does not limit the types of thermal stabilizers and antioxidants. In some embodiments, the thermal stabilizer includes at least one of a rare earth thermal stabilizer and a polyamine thermal stabilizer; the antioxidant includes at least one of a hindered phenol antioxidant and a thioester antioxidant.

[0048] In other embodiments, the hindered phenol antioxidant includes at least one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (antioxidant 1010), β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (antioxidant 1076), and triethylene glycol bis[β-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate] (antioxidant 245); and the thioester antioxidant includes at least one of dilauryl thiodipropionate (DLTP) and dioctadecyl thiodipropionate (DSTOP).

[0049] The above types of heat stabilizers and antioxidants have good compatibility and can be mixed evenly with each other. It is not easy for effective substances to precipitate in the high-temperature resistant polyamide hot melt adhesive during long-term storage due to poor compatibility. On the contrary, the compound use can effectively improve the stability of polyamide in the high-temperature resistant polyamide hot melt adhesive in high-temperature hot oxygen environment, and it is not easy to cause glue dripping, while ensuring the low-temperature operability of the glue and the sealing performance of the product after use.

[0050] In some embodiments, the antioxidant is a composite antioxidant, comprising the aforementioned hindered phenolic antioxidant and a thioester antioxidant, wherein the weight ratio of the hindered phenolic antioxidant to the thioester antioxidant is 1:(0.5-3). Such composite antioxidants exhibit superior antioxidant properties, particularly when combined with thermal stabilizers. These composite antioxidants can further enhance the structural stability of high-temperature resistant polyamide hot melt adhesives in long-term high-temperature environments, reducing the risk of adhesive smearing. While ensuring low-temperature operability during application and ensuring post-use sealing performance, the product exhibits superior performance.

[0051] In some embodiments, the high temperature resistant polyamide hot melt adhesive of the present invention comprises the following components, calculated by weight:

[0052]

[0053]

[0054] Calculated by weight as above,

[0055] The polyamide hot melt adhesive can be 50 parts, 51 parts, 52 parts, 53 parts, 54 parts, 55 parts, 56 parts, 57 parts, 58 parts, 59 parts, 60 parts, 61 parts, 62 parts, 63 parts, 64 parts, 65 parts, 66 parts, 67 parts, 68 parts, 69 parts or 70 parts;

[0056] Methyl vinyl silicone rubber can be 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, 20 parts, 21 parts, 22 parts, 23 parts, 24 parts or 25 parts;

[0057] The vulcanizing agent can be 1 part, 1.2 parts, 1.5 parts, 1.6 parts, 1.7 parts, 2 parts, 2.2 parts, 2.5 parts, 2.8 parts or 3 parts;

[0058] Polyisobutylene can be 5, 5.5, 5.8, 6, 6.4, 6.5, 6.9, 7, 7.3, 7.5, 7.8, 8, 8.3, 8.5, 8.6, 8.9, or 9 parts;

[0059] The ethylene-acrylic acid copolymer can be 2 parts, 2.3 parts, 2.5 parts, 2.8 parts, 3 parts, 3.3 parts, 3.5 parts, 3.8 parts, 4 parts, 4.5 parts, 4.7 parts, 4.9 parts, 5 parts, 5.1 parts, 5.5 parts, 5.9 parts or 6 parts.

[0060] In addition, based on the above raw material components, 0.05-0.15 parts of heat stabilizers and 0.2-1 parts of antioxidants can be added by weight. Specifically, the heat stabilizer can be 0.05 parts, 0.07 parts, 0.08 parts, 0.1 parts, 0.11 parts, 0.12 parts, 0.13 parts, 0.14 parts or 0.15 parts; the antioxidant can be 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts or 1 parts.

[0061] Under the above weight ratio, it is more conducive to obtaining a product with high transparency, no solvent, environmental protection, good high temperature resistance and low temperature resistance, and the sizing can be operated at a lower temperature.

[0062] The present invention also provides a method for preparing the high temperature resistant polyamide hot melt adhesive as described above, referring to Figure 1 , including the following steps:

[0063] S10, mixing methyl vinyl silicone rubber and ethylene-acrylic acid copolymer to obtain a compatibilized silicone rubber;

[0064] S20, melt-blending the polyamide hot melt adhesive and polyisobutylene, then adding the compatibilized silicone rubber and vulcanizing agent of step S10, and preparing the high-temperature resistant polyamide hot melt adhesive by dynamic vulcanization.

[0065] In step S10, the methyl vinyl silicone rubber and the ethylene-acrylic acid copolymer are fully mixed so that the molecular chains in the ethylene-acrylic acid copolymer and the molecular chains of the methyl vinyl silicone rubber form an entangled structure, which can improve the compatibility of the silicone rubber in the polyamide hot melt adhesive.

[0066] In some embodiments, weighed methyl vinyl silicone rubber and ethylene-acrylic acid copolymer can be added into the torque rheometer and mixed evenly.

[0067] Specifically, the methyl vinyl silicone rubber and ethylene-acrylic acid copolymer are melt-blended at a temperature of 120-140°C and a rotational speed of 50-70 rpm for 3-5 minutes to fully mix the methyl vinyl silicone rubber and ethylene-acrylic acid copolymer, before discharging the melt and allowing it to stand for 1-2 days to obtain the compatibilized silicone rubber. These mixing conditions enhance the mixing of the methyl vinyl silicone rubber and the ethylene-acrylic acid copolymer, promoting the formation of an entangled structure between the molecular chains of the ethylene-acrylic acid copolymer and the molecular chains of the methyl vinyl silicone rubber.

[0068] In step S20, in addition to melt-blending the polyamide hot melt adhesive and polyisobutylene, a heat stabilizer and an antioxidant may also be added for melt-blending. The addition of the heat stabilizer and the antioxidant can effectively improve the long-term use stability of the polyamide in the high-temperature resistant polyamide hot melt adhesive in a high-temperature hot oxygen environment, making it less likely to cause glue dripping, while ensuring the low-temperature operability of the glue and the sealing performance of the product after use.

[0069] In some embodiments, the raw materials in step S20 may be melt-blended in a torque rheometer.

[0070] In some embodiments, the melt blending temperature, rotation speed, and time are 120-140°C, 50-70 rpm, and 3-5 minutes, respectively. These conditions promote mixing of the components, resulting in a more stable, high-temperature-resistant polyamide hot melt adhesive that is easier to store, less susceptible to additive precipitation, and better able to perform.

[0071] After completing the melt blending of the above raw material components, the compatibilized silicone rubber and the vulcanizer of step S10 are added and mixed again, and mixed evenly by dynamic vulcanization. The temperature of the dynamic vulcanization method can be 120-140°C, and the rotation speed of the dynamic vulcanization method can be 50-70r / min. Under the above high shear mixing conditions, the methyl vinyl silicone rubber and the polyamide hot melt adhesive in the compatibilized silicone rubber can be fully mixed and evenly mixed, and the methyl vinyl silicone rubber forms a network unit structure through dynamic vulcanization, and the network unit structure can play a supporting role. In addition, the dynamic vulcanization method can also promote the interfacial grafting reaction between the methyl vinyl silicone rubber in the compatibilized silicone rubber and the polyamide hot melt adhesive, which can greatly improve the problem that the polyamide molecular chain is prone to glue flow under high temperature conditions.

[0072] In addition, the silane bond energy of methyl vinyl silicone rubber itself is relatively large and is less affected by high temperatures. It can effectively prevent the slippage of the polyamide molecular chains in the product, greatly improving the product's high temperature resistance. Even when used in a high temperature environment, it is not easy for the rubber to drip.

[0073] In some embodiments, the compatibilized silicone rubber can be added and mixed for 3-5 minutes to fully mix the rubber with the polyamide hot melt adhesive and polyisobutylene. Next, the vulcanizing agent is added and mixed for another 4-6 minutes before discharging the mixture to obtain the high-temperature resistant polyamide hot melt adhesive. This facilitates the vulcanization of the methyl vinyl silicone rubber and allows it to form a more stable network unit structure.

[0074] In some embodiments, a dry polyamide hot melt adhesive is preferred to prevent degradation of the polyamide hot melt adhesive due to excess moisture during subsequent processing, which can ultimately affect the quality of the heat-resistant polyamide hot melt adhesive. Specifically, the polyamide hot melt adhesive can be dried in a forced air drying oven at 50°C-75°C for 12-24 hours to remove absorbed moisture.

[0075] In some embodiments, the high temperature resistant polyamide hot melt adhesive may be shaped according to usage requirements.

[0076] In one embodiment, the high-temperature resistant polyamide hot melt adhesive can be placed in a flat vulcanizer, hot-pressed for 1-3 minutes at 120°C-150°C and 5MPa-15MPa, and then cold-pressed for 2-5 minutes to obtain a high-temperature resistant polyamide hot melt adhesive sheet.

[0077] In another embodiment, the high temperature resistant polyamide hot melt adhesive may be processed and molded into a desired shape by extrusion molding, for example, into a rod shape.

[0078] Specifically, during the extrusion molding process, the temperature of the feeding section is 75-85° C., the temperature of the melting section is 100-110° C., the temperature of the metering section is 120-130° C., and the rotation speed is 65-75 r / min.

[0079] The technical solutions of the present invention are further described in detail below in conjunction with specific embodiments. It should be understood that the following specific embodiments are only used to explain the present invention and are not used to limit the present invention.

[0080] The polyamide hot melt adhesive used in the following examples is a linear polyamide hot melt adhesive with a melting point of 90°C-105°C. If the polyamide hot melt adhesive has absorbed moisture, it can be dried in a forced air drying oven at 50°C-75°C for 12-24 hours to remove the absorbed moisture. The dried polyamide hot melt adhesive can then be used to prepare the high-temperature-resistant polyamide hot melt adhesive of the present invention. The weight of the dried polyamide hot melt adhesive shall be used as the standard.

[0081] Example 1

[0082] Weigh the raw materials according to Tables 1 to 2 and prepare according to the following method:

[0083] S10, placing methyl vinyl silicone rubber and ethylene-acrylic acid copolymer in a torque rheometer, setting the temperature to 140°C and the speed to 50 r / min, melt blending for 5 minutes, discharging, and standing for 2 days to obtain a compatibilized silicone rubber;

[0084] S20, adding the polyamide hot melt adhesive and the remaining raw materials except the vulcanizer to the torque rheometer, melt blending for 5 minutes at 140°C and 50 r / min, then adding the compatibilized silicone rubber of step S10, mixing by dynamic vulcanization at 140°C and 50 r / min for 5 minutes, fully mixing, then adding the vulcanizer, continuing to mix for 6 minutes and then discharging to obtain the high temperature resistant polyamide hot melt adhesive.

[0085] Example 2

[0086] Weigh the raw materials according to Tables 1 to 2, and then prepare according to the following method:

[0087] S10, placing the silicone rubber and the compatibilizer in a torque rheometer, setting the temperature to 130°C and the speed to 60 r / min, performing melt blending for 4 minutes, discharging the mixture, and standing it for 1.5 days to obtain the compatibilized silicone rubber;

[0088] S20, adding the polyamide hot melt adhesive and the remaining raw materials except the vulcanizer to the torque rheometer, melt blending for 4 minutes at 130°C and 60 r / min, then adding the compatibilized silicone rubber of step S10, mixing by dynamic vulcanization method at 130°C and 60 r / min for 4 minutes, fully mixing, then adding the vulcanizer, continuing to mix for 5 minutes and then discharging to obtain the high temperature resistant polyamide hot melt adhesive.

[0089] Example 3

[0090] Weigh the raw materials according to Tables 1 to 2, and then prepare according to the following method:

[0091] S10, placing methyl vinyl silicone rubber and ethylene-acrylic acid copolymer in a torque rheometer, setting the temperature to 120°C and the speed to 70 r / min, melt blending for 3 minutes, discharging, and standing for 1 day to obtain a compatibilized silicone rubber;

[0092] S20, add the polyamide hot melt adhesive and the remaining raw materials except the vulcanizer to the torque rheometer, melt blend them at 120°C and 70 r / min for 3 minutes, then add the compatibilized silicone rubber of step S10, mix them by dynamic vulcanization at 120°C and 70 r / min for 3 minutes, mix them thoroughly, then add the vulcanizer, continue mixing for 4 minutes and then discharge the material to obtain the high temperature resistant polyamide hot melt adhesive.

[0093] Examples 4 to 23

[0094] In Examples 4 to 23, raw materials were weighed according to Tables 1 to 2, respectively, and then high-temperature resistant polyamide hot melt adhesives were prepared according to the preparation method of Example 1.

[0095] Comparative Example 1

[0096] Comparative Example 1 The raw materials were selected with reference to Example 1, but the difference was that a polyamide hot melt adhesive with a melting point of 160-220°C was used instead of the polyamide hot melt adhesive in Example 1. The preparation method was the same as that in Example 1 to obtain a high-temperature resistant polyamide hot melt adhesive.

[0097] Comparative Example 2

[0098] Comparative Example 2 selected raw materials with reference to Example 1, but the difference was that methyl vinyl silicone rubber was not added. The preparation method was the same as that of Example 1 to obtain a high-temperature resistant polyamide hot melt adhesive.

[0099] Comparative Example 3

[0100] Comparative Example 3 selected raw materials with reference to Example 1, but the difference was that the amount of methyl vinyl silicone rubber added was 10 parts. The preparation method was the same as that of Example 1 to obtain a high-temperature resistant polyamide hot melt adhesive.

[0101] Comparative Example 4

[0102] Comparative Example 4 selected raw materials with reference to Example 1, but the difference was that the amount of methyl vinyl silicone rubber added was 40 parts. The preparation method was the same as that of Example 1, and the product, high-temperature resistant polyamide hot melt adhesive, was obtained.

[0103] Comparative Example 5

[0104] Comparative Example 5 selects raw materials with reference to Example 1, but the difference is that no vulcanizing agent is added. The preparation method is the same as that of Example 1 to obtain a high-temperature resistant polyamide hot melt adhesive.

[0105] Comparative Example 6

[0106] Comparative Example 6 selects raw materials with reference to Example 1, but the difference is that the polyamide hot melt adhesive is 90 parts, and the preparation method is the same as that of Example 1 to obtain a high-temperature resistant polyamide hot melt adhesive.

[0107] Comparative Example 7

[0108] The raw material composition of Comparative Example 7 is the same as that of Example 1, but the preparation method is different, except that the operation of step S10 is not performed, and the following preparation is performed with reference to step S20 of the example:

[0109] Polyamide hot melt adhesive, polyisobutylene, thermal stabilizer and antioxidant were added to the torque rheometer and melt-blended at 140°C and 50 r / min for 5 minutes. Then, methyl vinyl silicone rubber and ethylene-acrylic acid copolymer were added and mixed by dynamic vulcanization at 140°C and 50 r / min for 5 minutes. After thorough mixing, vulcanizing agent was added and mixing was continued for 6 minutes before discharging to obtain high-temperature resistant polyamide hot melt adhesive.

[0110] Comparative Example 8

[0111] The raw material composition of Comparative Example 8 is the same as that of Example 1, but the preparation method is different. The difference is that in step S20, after adding the compatibilized silicone rubber and vulcanizing agent of step S10, dynamic vulcanization is not used for mixing, that is, ordinary melt blending is performed to prepare the high-temperature resistant polyamide hot melt adhesive.

[0112] Table 1 Combination of heat stabilizers and antioxidants (parts by weight)

[0113]

[0114]

[0115] “ / ” in the table means not added.

[0116] Table 2 Composition of high temperature resistant polyamide hot melt adhesive raw materials of Examples and Comparative Examples (parts by weight)

[0117]

[0118]

[0119] Note: “ / ” in the table means no addition. For the addition of heat stabilizers and antioxidants, please refer to Table 1.

[0120] Performance Testing

[0121] The high temperature resistant polyamide hot melt adhesives obtained in the examples and comparative examples were molded to obtain sheet-like high temperature resistant polyamide hot melt adhesives, as follows:

[0122] The high temperature resistant polyamide hot melt adhesives of the embodiment and comparative example were placed in a flat vulcanizer, hot pressed for 1-3 minutes at 120-150° C. and 5-15 MPa, and then cold pressed for 2-5 minutes to obtain sheet-shaped high temperature resistant polyamide hot melt adhesives.

[0123] The sheet-like high-temperature resistant polyamide hot melt adhesives obtained in the examples are marked as PA-1 to PA-23,

[0124] The sheet-like high-temperature-resistant polyamide hot-melt adhesives obtained in the comparative examples are marked as D-1 to D-8, respectively.

[0125] The gluing temperature, gluing effect, high temperature aging performance and low temperature performance of the high temperature resistant polyamide hot melt adhesive completed above were tested respectively. The test methods are as follows:

[0126] 1. High temperature aging test: Prepare a colloid sample of a certain thickness smeared on the surface of the copper plate, place the sample vertically in a high temperature aging oven at 150℃, age for 480h, and observe whether the adhesive layer has sagging or glue dripping; place the sample vertically in a high temperature aging oven at 125℃, age for 3000h, and observe whether the adhesive layer has sagging or glue dripping.

[0127] Test result judgment: whether the adhesive layer has sag or glue dripping; whether the air tightness of the wiring harness is good.

[0128] 2. Low-temperature impact test: Using a high-temperature and low-temperature chamber and a low-temperature impact device, store a colloid sample of a certain thickness applied to the surface of a copper plate and an automotive wiring harness with a hot-melt adhesive sealed joint in a high-temperature and low-temperature chamber at -40°C for 4 hours. Then, let a 200-gram weight fall freely into the middle of the sample to check whether there are cracks in the adhesive layer; the automotive wiring harness is also tested for air tightness.

[0129] Test results determine whether cracks appear due to low-temperature impact and whether the wiring harness is airtight.

[0130] Table 3 Performance comparison of the products obtained in the examples and comparative examples

[0131]

[0132]

[0133]

[0134] It can be seen from Table 3 that the high-temperature resistant polyamide hot melt adhesive obtained in the embodiment of the present invention can also be smoothly applied at 90°C, with a lower application temperature; in the high-temperature aging test, the adhesive layer did not experience sagging or dripping, the wiring harness had good air tightness, had good high-temperature resistance and weather resistance, and could meet the use requirements under high-temperature conditions of 150°C; and in the low-temperature impact test, there were no cracks, the wiring harness had good air tightness, and had good low-temperature resistance.

[0135] The high-temperature resistant polyamide hot melt adhesive of the present invention has good high-temperature resistance, low-temperature resistance and weather resistance, and has a low gluing temperature, and can be widely used in industries such as electronic components, automotive parts, wiring harnesses and cables.

[0136] Comparative Example 1 uses an amide hot melt adhesive with a melting point of 160°C-220°C. The melting point is relatively high, and the lowest gluing temperature of the obtained product reaches 160°C.

[0137] In comparative example 2, no methyl vinyl silicone rubber was added. The obtained product had sagging and dripping of the adhesive layer in the high-temperature aging test, and air leakage in the wiring harness. In the low-temperature impact test, cracks and air leakage also occurred in the wiring harness.

[0138] Comparative Examples 3 to 4 add less or more methyl vinyl silicone rubber, which may result in insufficient glue discharge, sag and glue dripping of the glue layer in the high-temperature aging test, air leakage of the wiring harness, or cracks in the low-temperature impact test, air leakage of the wiring harness, and other unqualified phenomena.

[0139] In Comparative Example 5, no vulcanizing agent is added, and the obtained product has poor high-temperature aging resistance, the adhesive layer is prone to sag and glue dripping, and the wiring harness will leak.

[0140] When more polyamide hot melt adhesive is added in Comparative Example 6, the obtained product has poor high temperature aging resistance, the adhesive layer is prone to sag and glue dripping, and the wiring harness will leak.

[0141] In Comparative Example 7, the compatibilized silicone rubber was not prepared in advance, and the obtained product had poor high-temperature aging resistance, the adhesive layer was prone to sag and glue dripping, and the wiring harness would leak.

[0142] In Comparative Example 8, the dynamic vulcanization method was not used for mixing in step S20, and the product was basically not glued, and the wiring harness leaked during the high-temperature aging test.

[0143] The above are only preferred embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A high temperature resistant polyamide hot melt adhesive, characterized in that: Calculated by weight, the high temperature resistant polyamide hot melt adhesive includes the following components: 50-70 parts of polyamide hot melt adhesive, 15-25 parts of methyl vinyl silicone rubber, 1-3 parts of vulcanizing agent, 5-9 parts of polyisobutylene, 2-6 parts of ethylene-acrylic acid copolymer; The melting point of the polyamide hot melt adhesive is 90°C-105°C; The preparation method of the high temperature resistant polyamide hot melt adhesive comprises the following steps: mixing the methyl vinyl silicone rubber and ethylene-acrylic acid copolymer to obtain a compatibilized silicone rubber; The polyamide hot melt adhesive and polyisobutylene are melt-blended, and then the compatibilized silicone rubber and a vulcanizing agent are added to prepare the high-temperature resistant polyamide hot melt adhesive through a dynamic vulcanization method.

2. The high temperature resistant polyamide hot melt adhesive according to claim 1, characterized in that: The vulcanizing agent includes at least one of dicumyl peroxide, benzoyl peroxide, and di-tert-butyl peroxide.

3. The high temperature resistant polyamide hot melt adhesive according to claim 1, characterized in that: Calculated by weight, the high temperature resistant polyamide hot melt adhesive also includes the following components: 0.05-0.15 parts of heat stabilizer, 0.2-1 parts of antioxidant.

4. The high temperature resistant polyamide hot melt adhesive according to claim 3, characterized in that: The thermal stabilizer includes at least one of a rare earth thermal stabilizer and a polyamine thermal stabilizer.

5. The high temperature resistant polyamide hot melt adhesive according to claim 3, characterized in that: The antioxidant comprises at least one of a hindered phenol antioxidant and a thioester antioxidant; And / or, the antioxidant is a composite antioxidant, which is compounded by a hindered phenol antioxidant and a thioester antioxidant, wherein the weight ratio of the hindered phenol antioxidant to the thioester antioxidant is 1:(0.5-3).

6. The high temperature resistant polyamide hot melt adhesive according to claim 5, characterized in that: The hindered phenol antioxidant includes at least one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (antioxidant 1010), β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (antioxidant 1076), and triethylene glycol bis[β-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate] (antioxidant 245); And / or, the thioester antioxidant includes at least one of dilauryl thiodipropionate (DLTP) and dioctadecyl thiodipropionate (DSTOP).

7. The high temperature resistant polyamide hot melt adhesive according to any one of claims 1 to 6, characterized in that: The high temperature resistant polyamide hot melt adhesive is transparent; and / or the gluing temperature of the high temperature resistant polyamide hot melt adhesive is below 105°C.

8. A method for preparing the high temperature resistant polyamide hot melt adhesive according to any one of claims 1 to 7, characterized in that: The following steps are involved: The compatibilized silicone rubber is obtained by mixing methyl vinyl silicone rubber and ethylene-acrylic acid copolymer; The polyamide hot melt adhesive and polyisobutylene are melt-blended, and then the compatibilized silicone rubber and the vulcanizing agent are added to prepare the high-temperature resistant polyamide hot melt adhesive through a dynamic vulcanization method.

9. The method for preparing the high temperature resistant polyamide hot melt adhesive according to claim 8, characterized in that: In the step of melt-blending the polyamide hot melt adhesive and polyisobutylene, a heat stabilizer and an antioxidant are also added for melt-blending; And / or, the melt blending temperature is 120° C.-140° C., the melt blending speed is 50-70 r / min, and the melt blending time is 3-5 min; And / or, the temperature of the dynamic vulcanization method is 120° C.-140° C., and the rotation speed is 50-70 r / min.

10. Use of the high-temperature resistant polyamide hot melt adhesive according to any one of claims 1 to 7 in the fields of electronic components, automotive parts, wiring harnesses and cables.

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