A high-viscosity, high-temperature resistant dimer acid type polyamide hot melt adhesive and its preparation method

Abstract

This invention provides a high-viscosity, high-temperature resistant dimer acid type polyamide hot melt adhesive and its preparation method, comprising the following components by mass fraction: 100 parts dimer acid type polyamide, 0.01-0.1 parts free radical initiator, 0.25-0.5 parts tris(triphenylphosphine)copper bromide, 0.5-1.0 parts hindered phenolic antioxidant, 1-5 parts polyether defoamer, and 0.1-0.5 parts higher alcohol defoamer. The preparation method provided by this invention is simple and highly operable. The dimer acid type polyamide hot melt adhesive prepared by this method possesses excellent temperature resistance and high viscosity, expanding the application range of existing dimer acid type polyamide hot melt adhesives.

Description

Technical Field

[0001] This invention relates to the field of high-temperature resistant hot melt adhesive technology, and further to a high-viscosity, high-temperature resistant dimer acid type polyamide hot melt adhesive and its preparation method. Background Technology

[0002] Traditional hot melt adhesives use EVA as the main base material, but its softening and service temperatures are below 100℃, making it difficult to achieve high temperature resistance and meet the growing demand. Therefore, PA hot melt adhesives with polyamide as the main base material have emerged. Polyamides that can be used as hot melt adhesives mainly fall into two categories: copolymer polyamides and dimer acid polyamides. Copolymer polyamides are obtained by the condensation polymerization of diamines and diacids with simple molecular structures. They have regular chain structures, high crystallinity, and excellent temperature resistance, but suffer from poor flexibility and are prone to cracking.

[0003] Dimeric acid polyamides are obtained by the condensation polymerization of dimer acids and diamines. The dimer acid monomer typically possesses more than one long-chain side group and unsaturated carbon ring molecules. These long-chain side groups and cyclic structures increase the intermolecular spacing of the polyamide molecules obtained through condensation polymerization, reducing the regularity of the molecular chain structure. Therefore, dimer acid polyamides have very low crystallinity, appearing yellow and transparent. Their flexibility is significantly better than copolymer polyamides, but their temperature resistance is poor, typically only reaching 100-120℃. Simultaneously, they have low viscosity and excessively good flowability. Therefore, improving the high-temperature resistance and addressing the low viscosity and poor stability of dimer acid polyamides while maintaining their flexibility is crucial for the development of novel polyamide hot melt adhesives. Summary of the Invention

[0004] To address the problems of poor high-temperature resistance and low viscosity of dimer acid polyamides in existing technologies, the present invention aims to provide a high-viscosity, high-temperature resistant dimer acid polyamide hot melt adhesive and its preparation method. The present invention utilizes the unsaturated bonds of dimer acid polyamides for chain extension and crosslinking, thereby increasing the degree of polymerization and molecular weight of dimer acid polyamides to improve temperature resistance and viscosity.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A high-viscosity, high-temperature resistant dimer acid type polyamide hot melt adhesive comprises the following components in parts by weight: 100 parts dimer acid type polyamide, 0.01-0.1 parts free radical initiator, 0.25-0.5 parts tris(triphenylphosphine)copper bromide, 0.5-1.0 parts hindered phenolic antioxidant, 1-5 parts polyether defoamer, and 0.1-0.5 parts higher alcohol defoamer.

[0007] In some technical solutions, the dimer acid type polyamide is prepared by polycondensation reaction of a diamine with at least one of dimer acids and their derivatives.

[0008] In some technical solutions, the free radical initiator is any one or more of peroxide initiators and azo initiators.

[0009] In some technical solutions, the peroxide initiator is any one or more of bis(butylperoxide) diisopropylbenzene and its derivatives; the azo initiator is any one or more of polyester-type azobisisobutyronitrile and its derivatives.

[0010] In some technical solutions, the hindered phenolic antioxidant is any one or more of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and its derivatives, and N,N-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexamethylenediamine and its derivatives.

[0011] In some technical solutions, the polyether defoamer is any one or more of GP-type glycerol polyether and its derivatives, GPE-type polyoxyethylene ether and its derivatives, and PPG-type polypropylene glycol and its derivatives.

[0012] In some technical solutions, the high-carbon alcohol defoamer is any one or a combination of pentaerythritol ether and its derivatives and pentaerythritol ether and its derivatives of polyoxyethylene.

[0013] This invention also provides a method for preparing a high-viscosity, high-temperature resistant dimer acid type polyamide hot melt adhesive, characterized by comprising the following steps:

[0014] S1. Heat the dimer acid type polyamide to a viscous flow state, add the free radical initiator, stir and mix, and gradually increase the temperature. After the temperature reaches the preset temperature, keep the temperature constant for a period of time.

[0015] S2. After adding a high-carbon alcohol defoamer during the constant-temperature reaction, stir slowly. After the constant-temperature reaction is completed, a premix is ​​obtained.

[0016] S3. Add tris(triphenylphosphine) bromide, hindered phenolic antioxidant, and polyether defoamer to the premix and mix them together to obtain a mixture. After extrusion granulation and drying, the mixture is used to obtain the high viscosity, high temperature resistant dimer acid type polyamide hot melt adhesive granules.

[0017] In some technical solutions, the preset temperature in step S1 is 110-120℃, and / or; the temperature for co-mixing in step S3 is 150℃, and / or; and the temperature for extrusion granulation in step S3 is 120-180℃.

[0018] The present invention also provides the application of the above-mentioned high viscosity, high temperature resistant dimer acid type polyamide hot melt adhesive in the field of automotive wiring harnesses.

[0019] Compared with the prior art, the present invention can bring the following beneficial effects:

[0020] 1. The dimer acid type polyamide hot melt adhesive provided by the present invention completes the chain extension reaction and intramolecular cross-linking reaction through the double bond on the dimer acid type polyamide molecule, thereby indirectly increasing the degree of polymerization and molecular weight of the dimer acid type polyamide, and the intramolecular cross-linking structure forms a micro network structure, which improves the temperature resistance and viscosity of the dimer acid type polyamide hot melt adhesive.

[0021] 2. The dimer acid type polyamide hot melt adhesive provided by this invention can adjust the degree of chain extension reaction by adjusting the amount of initiator, reaction time and reaction temperature during the preparation process, thereby adjusting the temperature resistance properties such as softening point and viscosity to meet the different needs of individual customers.

[0022] 3. The dimer acid type polyamide hot melt adhesive provided by the present invention consumes some of the easily reactive double bonds and cyclic structures through chain extension reaction. Furthermore, by introducing the compound use of macromolecular organic copper salt and hindered phenolic oxidant, and by selecting other added components with large molecular weight and more stable substances such as polyether defoamer and macromolecular azobisisobutyronitrile, the dimer acid type polyamide hot melt adhesive prepared by the present invention has good antioxidant and anti-aging properties.

[0023] 4. The dimer acid type polyamide hot melt adhesive prepared by this invention has improved properties such as temperature resistance, viscosity and stability, while retaining the original advantages of dimer acid type polyamide hot melt adhesive such as transparency and good toughness, which greatly expands the application field of dimer acid type polyamide hot melt adhesive.

[0024] 5. The heat shrink tubing preparation method provided by this invention is simple, requires no special process or equipment investment, has a wide range of environmentally friendly raw material sources, good compatibility between raw materials, strong plasticity, convenient transportation and installation, and is suitable for large-scale mass production. Attached Figure Description

[0025] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0026] Figure 1 The equation flowchart for the chain extension reaction of the dimer acid type polyamide provided by the present invention is shown. Detailed Implementation

[0027] The present invention will be further described below with reference to specific embodiments, but these embodiments are merely exemplary and do not constitute any limitation on the scope of the present invention. Those skilled in the art should understand that various improvements and modifications can be made without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

[0028] Dimeric acid polyamides are obtained by polycondensation of dimer acids and diamines. Dimeric acids, as monomers, usually have more than one long-chain side group and unsaturated carbon ring molecules. The long-chain side group and cyclic structure increase the intermolecular distance of the polyamide molecules obtained by polycondensation and reduce the regularity of the molecular chain structure. Therefore, dimer acid polyamides have very low crystallinity, are yellow and transparent, and have significantly better flexibility than copolymer polyamides. However, the complex monomer structure brings excellent flexibility to dimer acid polyamides, but also brings many negative effects: (1) The steric structure of the monomer makes it difficult for the polycondensation reaction to proceed. Therefore, the degree of polymerization (molecular weight) of dimer acid polyamides is much lower than that of copolymer polyamides. This makes the high temperature resistance of dimer acid polyamides much lower than that of copolymer polyamides, usually only 100-120℃; (2) The polyamide obtained after polycondensation inherits the long chain side groups and cyclic structure of the monomer, which increases the intermolecular distance. This results in the dimer acid polyamide having low viscosity and good fluidity. When used as a hot melt adhesive, it often overflows excessively during processing and cannot play an effective filling role; (3) Some active crown energy groups originally carried by dimer acid monomers, such as double bonds, cyclic molecules, tertiary carbons, etc., are easy to participate in reactions such as oxidation and aging.

[0029] To meet the market's higher requirements for hot melt adhesive performance, the inventors have provided a modified formulation and preparation method for a dimer acid-based polyamide hot melt adhesive. This dimer acid-based polyamide hot melt adhesive, while retaining flexibility, exhibits improved temperature resistance and viscosity, as well as better processability and stability. Specifically:

[0030] The high-viscosity, high-temperature resistant dimer acid type polyamide hot melt adhesive provided by this invention comprises the following components in parts by weight:

[0031] 100 parts of dimer acid type polyamide, 0.01-0.1 parts of free radical initiator, 0.25-0.5 parts of triphenylphosphine bromide, 0.5-1.0 parts of hindered phenolic antioxidant, 1-5 parts of polyether defoamer, and 0.1-0.5 parts of higher alcohol defoamer.

[0032] In some embodiments, the aforementioned dimer acid polyamide is prepared by polycondensation reaction of a diamine with at least one of dimer acids and their derivatives.

[0033] More preferably, the dimer acid type polyamide is a polyamide resin obtained by polycondensation of any one or more of the dimer acids and their derivatives of fatty acids such as soybean oil fatty acid, tall oil fatty acid, and cottonseed oil fatty acid with a diamine.

[0034] In some embodiments, the free radical initiator is any one of a peroxide initiator and an azo initiator, or a combination of a peroxide initiator and an azo initiator.

[0035] More preferably, the peroxide initiator mentioned above is any one or more of bis(thiopropyl)peroxide diisopropylbenzene and its derivatives, and the azo initiator is any one or more of polyester-type azobisisobutyronitrile and its derivatives.

[0036] In some embodiments, the hindered phenolic antioxidant is any one or more of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and its derivatives, and N,N-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexamethylenediamine and its derivatives.

[0037] In some embodiments, the polyether defoamer is any one or more of GP-type glycerol polyether and its derivatives, GPE-type polyoxyethylene ether and its derivatives, and PPG-type polypropylene glycol and its derivatives.

[0038] In some embodiments, the higher alcohol defoamer is any one or a combination of pentaerythritol ether and its derivatives and pentaerythritol ether and its derivatives.

[0039] This invention also provides a method for preparing the high-viscosity, high-temperature resistant dimer acid type polyamide hot melt adhesive. The method involves preparing the high-viscosity, high-temperature resistant dimer acid type polyamide hot melt adhesive according to the above formula. The preparation process is simple and stable, and easy for large-scale industrial production. Specifically, it includes the following steps:

[0040] S1. Heat the dimer acid type polyamide to a viscous flow state, add the free radical initiator, stir and mix, and gradually increase the temperature. After reaching the preset temperature, keep the temperature constant for a period of time.

[0041] The preset temperature is 110-120℃.

[0042] In step S1, a free radical initiator is added to induce the opening of double bonds on the dimer acid polyamide molecule, thereby initiating an intramolecular crosslinking reaction or an intermolecular chain extension reaction. The chain extension reaction equation is as follows: Figure 1 As shown, the polymerization of dimer acid polyamides is inherently limited by the steric hindrance of the dimer acid monomers, resulting in a low degree of polymerization. This negatively impacts their temperature resistance and viscosity, making it difficult to improve. This invention addresses this issue by initiating a free radical reaction, utilizing the double bonds on the dimer acid monomer molecules to achieve both intermolecular chain extension and intramolecular crosslinking. The chain extension reaction increases the degree of polymerization and molecular weight, while the intramolecular crosslinking generates a micro-network structure. Both of these aspects improve the temperature resistance and low viscosity of dimer acid polyamides. Simple peroxide initiators do not have high temperature resistance, and some will be lost due to volatilization in this reaction environment. Therefore, this invention incorporates an azo initiator. On one hand, the introduced macromolecular azo compound itself is heat-resistant and can initiate the reaction, compensating for some of the lost peroxide. On the other hand, the volatilization of the peroxide initiator is also limited by the macromolecular azo compound.

[0043] It should be noted that the constant temperature reaction time should be at least 30 minutes, and the specific time can be extended as the amount of dimer acid polyamide used increases.

[0044] The temperature at which dimer acid type polyamide hot melt adhesive reaches the viscous flow state is 100-110℃. This temperature is not limited, and the specific temperature needs to be determined according to the specifications of the dimer acid type polyamide hot melt adhesive used in the actual preparation process.

[0045] S2. After adding the high-carbon alcohol defoamer during the constant-temperature reaction, stir slowly. After the constant-temperature reaction is completed, the premix is ​​obtained.

[0046] The chain extension or cross-linking reaction will increase the viscosity of the entire system, which will cause the air mixed in during stirring to form bubbles that are difficult to disappear automatically. The addition of a high-efficiency defoamer is required to eliminate the bubbles. The high-carbon alcohol defoamer added in step S2 of this invention is a more efficient high-carbon alcohol defoamer, which aims to quickly eliminate the bubbles formed during the reaction process to avoid adverse effects such as uneven reaction and excessive oxidation.

[0047] S3. Add tris(triphenylphosphine) bromide, hindered phenolic antioxidant, and polyether defoamer to the premix and mix them together to obtain a mixture. After extrusion granulation and drying, the mixture is used to obtain high-viscosity, high-temperature resistant dimer acid type polyamide hot melt adhesive granules.

[0048] Step S3 involves uniformly mixing the dimer acid type polyamide premix, triphenylphosphine bromide, hindered phenolic antioxidant, polyether defoamer, and hindered phenolic antioxidant in a blending device. The preferred mixing temperature is 150°C. The resulting mixture is then extruded, granulated, and dried to obtain high-viscosity, high-temperature resistant dimer acid type polyamide hot melt adhesive granules. The preferred extrusion granulation temperature is 120-180°C.

[0049] To address the poor stability and susceptibility to oxidation of dimer acid polyamides, this invention combines an organic copper salt and a hindered phenolic antioxidant. The organic copper salt selected is tris(triphenylphosphine) bromide, an antioxidant specific to the functional groups of polyamides. Cu ions can form complexes with amide bonds, and the stable complex structure reduces the reactivity of the amide functional groups, thereby improving stability.

[0050] Hindered phenolic antioxidants target the numerous side groups and tertiary carbons on dimer acid polyamides, protecting the matrix resin from oxidation by capturing active free radicals.

[0051] The synergistic use of organic copper salts and hindered phenolic antioxidants can significantly improve the stability of dimer acid-type polyamide hot melt adhesives.

[0052] The defoamer added in step S3 is a polyether defoamer with better stability and temperature resistance, and its component content is also larger, in order to fully eliminate bubbles formed by the release of trace amounts of water vapor or the mixing of air during granulation and extrusion.

[0053] Because hot melt adhesives have high viscosity, air can easily be incorporated during preparation, forming bubbles. If these bubbles are not sufficiently eliminated, it not only reduces the quality of the finished product and production efficiency but also poses risks during subsequent use. Preferably, in the preparation process provided by this invention, after adding the high-carbon alcohol defoamer and polyether defoamer, continuous slow stirring is performed to eliminate bubbles, reduce the hazards caused by bubbles, and improve the quality and yield of the hot melt adhesive product.

[0054] This invention also provides the application of the above-mentioned dimer acid type polyamide hot melt adhesive in the field of automotive wiring harnesses. For example, it can be used to prepare automotive wiring harness thermoplastic tubing. The automotive wiring harness heat shrink tubing prepared with this hot melt adhesive has high viscosity, high bonding quality, excellent high temperature resistance, and long service life, meeting the requirements of automotive wiring harnesses with high requirements for temperature resistance and bonding strength. It can also be applied in automotive parts manufacturing and other automotive industry fields to meet different user needs.

[0055] To better understand and apply the above solutions and to effectively demonstrate their corresponding benefits, this application also provides several embodiments as described below.

[0056] Example 1:

[0057] According to the mass fractions, take 100 parts of dimer acid type polyamide with a softening point of 106℃, 0.02 parts of peroxide initiator, 0.03 parts of azo initiator, 0.5 parts of higher alcohol defoamer, 2.5 parts of polyether defoamer, 0.5 parts of triphenylphosphine bromide, and 1 part of hindered phenolic oxidant.

[0058] First, heat 100 parts of dimer acid polyamide to a viscous flow state, add 0.02 parts of peroxide initiator and 0.03 parts of azo initiator and stir to mix. During the mixing process, gradually raise the temperature to 120°C and maintain the reaction at 120°C for 1 hour. After reacting at a constant temperature for 10 minutes, add 0.5 parts of high carbon alcohol defoamer to defoam. Stir slowly for 6 hours to obtain dimer acid polyamide premix.

[0059] The above-mentioned dimer acid type polyamide premix was mixed with 2.5 parts of polyether defoamer, 0.5 parts of tris(triphenylphosphine) copper bromide and 1 part of hindered phenolic oxidant, and then extruded and granulated by an extruder at an extrusion temperature of 120-160℃. After drying, a high viscosity, high temperature resistant dimer acid type polyamide hot melt adhesive was obtained.

[0060] Example 2:

[0061] According to the mass fractions, take 100 parts of dimer acid type polyamide with a softening point of 106℃, 0.05 parts of peroxide initiator, 0.03 parts of azo initiator, 0.5 parts of higher alcohol defoamer, 5 parts of polyether defoamer, 0.5 parts of triphenylphosphine bromide, and 1 part of hindered phenolic oxidant.

[0062] First, heat 100 parts of dimer acid polyamide to a viscous flow state, add 0.05 parts of peroxide initiator and 0.03 parts of azo initiator and stir to mix. During the mixing process, gradually raise the temperature to 110°C and maintain the reaction at 110°C for 2 hours. After reacting at a constant temperature for 10 minutes, add 0.5 parts of high carbon alcohol defoamer to defoam. Stir slowly for 10 hours to obtain dimer acid polyamide premix.

[0063] The above-mentioned dimer acid type polyamide premix was mixed with 5 parts of polyether defoamer, 0.5 parts of tris(triphenylphosphine) copper bromide and 1 part of hindered phenolic oxidant, and then extruded and granulated by an extruder at an extrusion temperature of 140-180℃. After drying, a high viscosity, high temperature resistant dimer acid type polyamide hot melt adhesive was obtained.

[0064] Example 3:

[0065] According to the mass fractions, take 100 parts of dimer acid type polyamide with a softening point of 98℃, 0.01 parts of peroxide initiator, 0.03 parts of azo initiator, 0.5 parts of higher alcohol defoamer, 1 part of polyether defoamer, 0.5 parts of triphenylphosphine bromide, and 1 part of hindered phenolic oxidant.

[0066] First, heat 100 parts of dimer acid polyamide to a viscous flow state, add 0.01 parts of peroxide initiator and 0.03 parts of azo initiator and mix. During the mixing process, gradually raise the temperature to 120°C and maintain the reaction at 120°C for 1 hour. After reacting at a constant temperature for 10 minutes, add 0.5 parts of high carbon alcohol defoamer to defoam. Stir slowly for 6 hours to obtain dimer acid polyamide premix.

[0067] The above-mentioned dimer acid type polyamide premix was mixed with 1 part of polyether defoamer, 0.5 parts of tris(triphenylphosphine) copper bromide and 1 part of hindered phenolic oxidant, and then extruded and granulated by an extruder at an extrusion temperature of 120-160℃. After drying, a high viscosity, high temperature resistant dimer acid type polyamide hot melt adhesive was obtained.

[0068] Example 4:

[0069] According to the mass fractions, take 100 parts of dimer acid type polyamide with a softening point of 98℃, 0.03 parts of peroxide initiator, 0.03 parts of azo initiator, 0.5 parts of higher alcohol defoamer, 2.5 parts of polyether defoamer, 0.5 parts of triphenylphosphine bromide, and 1 part of hindered phenolic oxidant.

[0070] First, heat 100 parts of dimer acid polyamide to a viscous flow state, add 0.03 parts of peroxide initiator and 0.03 parts of azo initiator and stir to mix. During the mixing process, gradually raise the temperature to 120°C and maintain the reaction at 120°C for 3 hours. After reacting at a constant temperature for 10 minutes, add 0.5 parts of high carbon alcohol defoamer to defoam. Stir slowly for 10 hours to obtain dimer acid polyamide premix.

[0071] The above-mentioned dimer acid type polyamide premix was mixed with 2.5 parts of polyether defoamer, 0.5 parts of tris(triphenylphosphine) copper bromide and 1 part of hindered phenolic oxidant, and then extruded and granulated by an extruder at an extrusion temperature of 130-180℃. After drying, a high viscosity, high temperature resistant dimer acid type polyamide hot melt adhesive was obtained.

[0072] Example 5:

[0073] According to the mass fractions, take 100 parts of dimer acid type polyamide with a softening point of 98℃, 0.05 parts of peroxide initiator, 0.03 parts of azo initiator, 0.5 parts of higher alcohol defoamer, 5 parts of polyether defoamer, 0.5 parts of triphenylphosphine bromide, and 1 part of hindered phenolic oxidant.

[0074] First, heat 100 parts of dimer acid polyamide to a viscous flow state, add 0.05 parts of peroxide initiator and 0.03 parts of azo initiator and stir to mix. During the mixing process, gradually raise the temperature to 120°C and maintain the reaction at 120°C for 4 hours. After reacting at a constant temperature for 10 minutes, add 0.5 parts of high carbon alcohol defoamer to defoam. Stir slowly for 10 hours to obtain dimer acid polyamide premix.

[0075] The above-mentioned dimer acid type polyamide premix was mixed with 5 parts of polyether defoamer, 0.5 parts of tris(triphenylphosphine) copper bromide and 1 part of hindered phenolic oxidant, and then extruded and granulated by an extruder at an extrusion temperature of 140-180℃. After drying, a high viscosity, high temperature resistant dimer acid type polyamide hot melt adhesive was obtained.

[0076] Comparative Example 1

[0077] Comparative Example 1 uses the unmodified dimer acid type polyamide hot melt adhesive with a softening point of 106°C, which was used in Examples 1 and 2.

[0078] Comparative Example 2

[0079] Comparative Example 2 uses the unmodified dimer acid type polyamide hot melt adhesive with a softening point of 98°C used in Examples 3-5.

[0080] The softening point and viscosity of the high-viscosity, high-temperature resistant dimer acid type polyamide hot melt adhesives provided in Examples 1-5 and Comparative Examples 1-2 were tested, as shown in Table 1.

[0081] Table 1. Softening point and viscosity of dimer acid-type polyamide hot melt adhesives provided in different embodiments and comparative examples.

[0082] Softening point (°C) Viscosity in mPas (170℃, 10 RPM) Comparative Example 1 106 7310 Comparative Example 2 98 6660 Example 1 149 143000 Example 2 161 216600 Example 3 137 76500 Example 4 148 141000 Example 5 175 277000

[0083] As shown in Table 1, compared with Comparative Example 1, the softening point and viscosity of the dimer acid type polyamide hot melt adhesive with a softening point of 106℃ in Examples 1 and 2 were significantly improved after processing with the preparation process provided by the present invention. Similarly, the softening point and viscosity of the dimer acid type polyamide hot melt adhesive products provided in Examples 3-5 were significantly higher than those in Comparative Example 2. It can be seen that the dimer acid type polyamide hot melt adhesive provided by the present invention has excellent temperature resistance and high viscosity, which improves the performance of existing dimer acid type hot melt adhesive products on the market and can be used in the automotive market. Moreover, the preparation process provided by the present invention is simple, easy to operate, and convenient for promotion and application.

[0084] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a high-viscosity, high-temperature resistant dimer acid type polyamide hot melt adhesive, characterized in that, Includes the following steps: S1. Heat 100 parts of dimer acid type polyamide to a viscous flow state, add 0.01-0.1 parts of free radical initiator, stir and mix, and gradually increase the temperature. After heating to 110-120℃, keep the temperature constant for a period of time to allow intermolecular chain extension reaction and intramolecular crosslinking reaction to occur through the double bonds on the polyamide molecule. S2. During the constant temperature reaction, add 0.1-0.5 parts of high carbon alcohol defoamer and stir slowly. After the constant temperature reaction is completed, a premix is ​​obtained. S3. Add 0.25-0.5 parts of tris(triphenylphosphine) bromide, 0.5-1.0 parts of hindered phenolic antioxidant, and 1-5 parts of polyether defoamer to the premix and mix them together at 150°C to obtain a mixture. Extrude the mixture at 120-180°C, granulate it, and dry it to obtain the high viscosity, high temperature resistant dimer acid type polyamide hot melt adhesive granules. The free radical initiator is composed of peroxide initiators and azo initiators.

2. The preparation method according to claim 1, characterized in that, The dimer acid type polyamide is prepared by polycondensation reaction of a diamine with at least one of dimer acids and their derivatives.

3. The preparation method according to claim 1, characterized in that, The peroxide initiator is any one or more of bis(butylperoxide) diisopropylbenzene and its derivatives; The azo initiator is any one or more of polyester-type azobisisobutyronitrile and its derivatives.

4. The preparation method according to claim 1, characterized in that, The hindered phenolic antioxidant is any one or more of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and its derivatives, and N,N-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexamethylenediamine and its derivatives.

5. The preparation method according to claim 1, characterized in that, The polyether defoamer is any one or more of GP-type glycerol polyether and its derivatives, GPE-type polyoxyethylene ether and its derivatives, and PPG-type polypropylene glycol and its derivatives.

6. The preparation method according to claim 1, characterized in that, The higher alcohol defoamer is any one or a combination of polyvinyl pentaerythritol ether and its derivatives and polyoxyethylene pentaerythritol ether and its derivatives.

7. A high-viscosity, high-temperature resistant dimer acid type polyamide hot melt adhesive, characterized in that, It is prepared by the preparation method according to any one of claims 1-6.

8. The application of a high-viscosity, high-temperature resistant dimer acid type polyamide hot melt adhesive as described in claim 7 in the field of automotive wiring harnesses.

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