Flame-retardant anti-aging copolyester hot melt adhesive and preparation method thereof

Abstract

The invention discloses a flame-retardant anti-aging copolyester hot melt adhesive and a preparation method thereof, and relates to the technical field of adhesives. The flame-retardant anti-aging copolyester hot melt adhesive is prepared from the following raw materials in parts by mass: 30-60 parts of copolyester resin, 15-30 parts of a halogen-free flame retardant, 1-5 parts of an anti-aging agent, 10-25 parts of tackifying resin, 5-15 parts of a plasticizer and 5-20 parts of inorganic filler. Compared with the problems that in the prior art, a halogen flame retardant is not environmentally friendly, a single halogen-free flame retardant needs a high adding amount to reach the standard, and the performance of the hot melt adhesive is prone to being damaged, a specific compound halogen-free flame retardant system is adopted, the high flame retardant grade can be achieved without the high adding amount, meanwhile, the using performance such as bonding strength can be prevented from being damaged, and the service life of the hot melt adhesive is prolonged. And the balance requirements of halogen-free environmental protection and use performance are met.

Description

Technical Field

[0001] This invention relates to the field of adhesive technology, specifically to a flame-retardant and anti-aging copolyester hot melt adhesive and its preparation method. Background Technology

[0002] Copolyester hot melt adhesives have been widely used in electronic component encapsulation, automotive interior bonding, building decoration material composites, and packaging industries due to their advantages such as solvent-free evaporation, fast curing speed, high bond strength, and good environmental performance. However, in practical applications, these hot melt adhesives often face harsh environmental challenges, and their insufficient anti-aging and flame-retardant properties are becoming increasingly prominent, becoming a key bottleneck restricting their application in high-end fields.

[0003] From the perspective of anti-aging performance, the ester groups in the copolyester molecular chain are prone to hydrolysis or breakage under environmental factors such as heat, oxygen, ultraviolet radiation, and humidity, leading to phenomena such as decreased adhesion, colloid cracking, and reduced flexibility in hot melt adhesives. For example, copolyester hot melt adhesives used for bonding outdoor electronic devices often experience interfacial debonding within 3-6 months after long-term ultraviolet irradiation; while products used near automotive engine compartments are prone to thermo-oxidative aging due to continuous high temperatures, with mechanical properties decreasing by more than 30%. Traditional anti-aging solutions often use hindered phenolic or benzotriazole single anti-aging agents, which can delay the aging process in the short term, but lack long-term weather resistance and fatigue resistance, making it difficult to meet the long-term use requirements under complex working conditions.

[0004] In terms of flame retardant performance, the electronics, automotive, and construction industries have increasingly stringent requirements for the flame retardant rating of materials, and halogen-free environmental protection has become the mainstream trend in the industry. Traditional copolyester hot melt adhesives mostly rely on halogenated flame retardants to achieve flame retardant effects, but they release toxic gases such as hydrogen chloride and hydrogen bromide when burning, which not only pollutes the environment but also causes secondary harm to equipment and human bodies. On the other hand, existing halogen-free flame retardant systems often have the problem of "difficulty in balancing flame retardant efficiency and performance"—a high amount of a single halogen-free flame retardant is required (more than 35 parts by weight) to meet the UL94-V0 flame retardant standard. Excessive addition will destroy the continuity of the copolyester matrix, resulting in a 20%-40% decrease in the adhesive strength of the hot melt adhesive, and problems such as flame retardant precipitation and brittleness of the adhesive are prone to occur, making it impossible to balance flame retardancy and performance.

[0005] In summary, the industry urgently needs to develop a copolyester hot melt adhesive that combines excellent flame retardant properties (especially halogen-free and environmentally friendly) with long-lasting anti-aging properties, while maintaining good bonding strength, flexibility, and processing stability, in order to meet the stringent requirements of high-end fields for the comprehensive performance of materials. Summary of the Invention

[0006] The purpose of this invention is to address the problems existing in the prior art by providing a flame-retardant and anti-aging copolyester hot melt adhesive and its preparation method, which combines halogen-free and environmentally friendly characteristics with high-efficiency flame retardant performance, long-lasting anti-aging ability, and excellent bonding strength, flexibility and processing stability, and can be adapted to the needs of high-end fields such as electronics, automobiles and construction.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is: a flame-retardant and anti-aging copolyester hot melt adhesive, which is made from raw materials comprising the following parts by weight: 30-60 parts copolyester resin, 15-30 parts halogen-free flame retardant, 1-5 parts anti-aging agent, 10-25 parts tackifying resin, 5-15 parts plasticizer, 5-20 parts inorganic filler, and 1-5 parts polyvinyl chloride.

[0008] The copolyester resin is prepared by polycondensation reaction of aromatic diacid, aliphatic diacid and aliphatic diol, wherein the molar ratio of aromatic diacid to aliphatic diacid is 7-9:3-1.

[0009] The anti-aging agent is a compound represented by Formula 1:

[0010] The structure of Equation 1 is as follows: ;

[0011] R1 in Formula 1 is selected from: hydrogen, cyano, and alkyl groups with 1-5 carbon atoms.

[0012] Furthermore, the aromatic dicarboxylic acid is at least one of terephthalic acid and isophthalic acid;

[0013] The aliphatic dicarboxylic acid is at least one of adipic acid and sebacic acid;

[0014] The aliphatic diol is at least one of 1,4-butanediol, 1,6-hexanediol, and ethylene glycol.

[0015] Furthermore, the halogen-free flame retardant is a compound system of at least one of ammonium polyphosphate, aluminum hypophosphite, and dimethyl methylphosphonate with melamine cyanurate, and the mass ratio is 2-1:1.

[0016] Furthermore, the tackifying resin is at least one of hydrogenated rosin glycerol ester, C5 petroleum resin, and terpene resin.

[0017] Furthermore, the plasticizer is at least one of diisononyl phthalate and dioctyl terephthalate.

[0018] Furthermore, the inorganic filler is at least one of nano-calcium carbonate, talc, and precipitated barium sulfate, with a particle size range of 800-1500 mesh.

[0019] Furthermore, the anti-aging agent is any one of the compounds shown in the following structures:

[0020] ;

[0021] ;

[0022] .

[0023] A method for preparing a flame-retardant and anti-aging copolyester hot melt adhesive includes the following steps:

[0024] a. Copolyester synthesis: Under nitrogen protection, the aromatic diacid, aliphatic diacid and aliphatic diol are added to a reactor, and a catalyst is added. Esterification reaction is carried out at 180-220℃; then polycondensation reaction is carried out at 220-250℃ under reduced pressure until the intrinsic viscosity of the product reaches 0.6-0.8 dl / g, to obtain copolyester resin;

[0025] b. Mixing: The copolyester resin is fed into a mixer in a molten state, and the plasticizer, tackifying resin, halogen-free flame retardant, anti-aging agent, polyvinyl chloride and inorganic filler are added in sequence. The mixture is then mixed at 160-180°C for 20-40 minutes until it is homogeneous.

[0026] c. Molding: The uniformly mixed molten material is extruded, cooled with water, granulated, and dried to obtain the copolyester hot melt adhesive granules.

[0027] Furthermore, the catalyst in step a is tetrabutyl titanate or antimony acetate, and its addition amount is 0.03%-0.05% of the total mass of aromatic diacids and aliphatic diacids;

[0028] In step b, the internal mixer rotates at 30-60 rpm.

[0029] Furthermore, step b is performed under a nitrogen atmosphere.

[0030] The anti-aging agent described in this invention is a novel compound whose molecular structure mainly comprises imino and aryl groups. The imino group has a strong hydrogen-donating capacity, effectively capturing free radicals initiated by heat, oxygen, or ultraviolet radiation, interrupting the chain reaction of polymer degradation. The anti-aging agent forms a stable intermediate through the reaction of the imino group with free radicals, preventing molecular chain breakage and thus maintaining the adhesive strength and flexibility of the hot melt adhesive. The aryl group structure has a conjugated system, capable of efficiently absorbing ultraviolet light energy and converting it into harmless heat energy, preventing direct attack of ultraviolet radiation on the copolyester molecular chain. The aryl group in the anti-aging agent reduces photodegradation reactions and extends service life by absorbing UV radiation. The imino group is responsible for internal free radical quenching, while the aryl group acts as an external ultraviolet barrier, overcoming the shortcomings of a single anti-aging agent. Simultaneously, the aryl group allows the anti-aging agent to be uniformly dispersed in the hot melt adhesive matrix, preventing precipitation and maintaining processing stability.

[0031] This invention addresses the core issues of insufficient anti-aging properties and the contradiction between flame retardancy and environmental friendliness in traditional copolyester hot melt adhesives. It achieves performance balance through a synergistic mechanism among the components: Specifically, a copolyester resin, polymerized from aromatic and aliphatic dicarboxylic acids in a specific molar ratio (7-9:3-1), serves as the matrix. Its flexible yet robust molecular structure provides both heat resistance and hydrolysis resistance, while also providing a stable carrier for the dispersion of other components. A halogen-free flame-retardant system is used, formulated with at least one of ammonium polyphosphate, aluminum hypophosphite, or dimethyl methylphosphonate and melamine cyanurate in a mass ratio of 2-1:1. Through the synergistic effect of gas phase (diluting combustible gases) and condensed phase (generating a phosphate carbon layer), only 15-30 parts of the additive are required to achieve the desired flame retardant effect. To meet the UL94-V0 flame retardant standard, the adhesive strength loss caused by high additive content is avoided. At the same time, a novel anti-aging agent with dual functional groups of imino (efficient free radical capture) and aryl (UV absorption) is used to effectively delay the thermo-oxidative and UV aging of ester groups through an internal and external synergistic mechanism. In addition, the tackifying resin, plasticizer, inorganic filler and polyvinyl chloride and other auxiliary components work together to enhance interfacial adhesion, flexibility, mechanical strength and promote dispersion. The mixing and low-temperature molding process at 160-180℃ under nitrogen protection ensures uniform mixing and processing stability of all components. In the end, the hot melt adhesive maintains excellent adhesive strength while possessing comprehensive properties of halogen-free environmental protection, high-efficiency flame retardancy and long-lasting anti-aging.

[0032] Compared with the prior art, the beneficial effects of the present invention are:

[0033] 1. Superior flame retardancy and environmental friendliness while also considering performance: Compared to the problems of existing technologies where halogenated flame retardants are not environmentally friendly and single halogen-free flame retardants require high addition amounts to meet standards and are prone to damaging hot melt adhesive performance, this invention uses a specific compound halogen-free flame retardant system, which can achieve a high flame retardancy rating without high addition amounts, while avoiding damage to performance such as bonding strength, thus meeting the balance between halogen-free environmental protection and performance.

[0034] 2. Longer and more stable anti-aging effect: Unlike traditional single anti-aging agents in the prior art, which have insufficient long-term weather resistance and fatigue resistance, the new anti-aging agent of this invention has dual functional groups, which can work synergistically to capture free radicals and absorb ultraviolet rays, effectively delaying the aging of copolyester molecular chains and improving the long-term stability of hot melt adhesives in complex environments.

[0035] 3. More balanced overall performance and stable processing: Compared with the existing technology, which has difficulty in taking into account multiple properties such as flame retardancy, anti-aging, bonding strength and flexibility, the present invention achieves halogen-free flame retardancy and long-term anti-aging while ensuring excellent bonding strength and flexibility through the synergistic cooperation of various components (copolyester matrix, flame retardant, anti-aging agent, auxiliary components, etc.) and specific preparation process. In addition, the components are evenly dispersed and have good stability during the processing. Attached Figure Description

[0036] Figure 1 This is the NMR spectrum of the anti-aging agent 1 described in this invention. Detailed Implementation

[0037] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] Preparation Example 1

[0039] Preparation of anti-aging agent 1:

[0040] ;

[0041] CAS number of compound 1: 777060-78-3;

[0042] CAS number of compound 2: 77095-51-3;

[0043] Under a nitrogen atmosphere, 10 g of compound 1, 12.22 g of compound 2, 12.71 g of triethylamine, 9.43 g of N,N-dimethylaminopyridine, and 130 mL of dry dichloromethane were added sequentially to the reaction system. The mixture was stirred at 60 °C for 4 hours. After the reaction, the pH of the system was adjusted to neutral with 0.1 mol / L hydrochloric acid aqueous solution. The organic phase was retained, and the solvent in the organic phase was removed by rotary evaporation. Silica gel column chromatography was performed using a mixture of petroleum ether and ethyl acetate as eluent, and the organic solvent was removed by rotary evaporation to obtain 14.97 g of compound 3. The mass spectrometry of compound 3 was MS-MS+1:304.

[0044] ;

[0045] CAS number of compound 4: 89378-75-6;

[0046] Under a nitrogen atmosphere, 14.97 g of compound 3, 8.03 g of compound 4, 9.99 g of triethylamine, 0.55 g of palladium acetate, 0.47 g of cuprous iodide, 0.64 g of triphenylphosphine, and 180 mL of tetrahydrofuran were added sequentially to the reaction system. The mixture was stirred at 80 °C for 6 hours, filtered, and the pH of the filtrate was adjusted to neutral using a 0.1 mol / L hydrochloric acid aqueous solution. The organic phase was retained, and the solvent in the organic phase was removed by rotary evaporation. Silica gel column chromatography was performed using a mixture of petroleum ether and ethyl acetate as eluent, and the organic solvent was removed by rotary evaporation to obtain 15.79 g of anti-aging agent 1. The mass spectrometry (MS-MS+1): 403 for anti-aging agent 1 is shown in the figure. Figure 1 .

[0047] Preparation Examples 2-6

[0048] In Preparation Examples 2-6, anti-aging agents 2-6 were prepared sequentially, following the preparation method of Preparation Example 1, except that compound 2 was replaced, and the rest remained the same as in Preparation Example 1. For details, please refer to Table 1.

[0049] Table 1.

[0050] Structure of compound 2 Anti-aging agent structure Mass spectrometry MS-MS+1 Preparation Example 2 CAS No.: 1312556-73-2 417 Preparation Example 3 CAS No.: 133845-02-0 417 Preparation Example 4 CAS No.: 588702-98-1 428 Preparation Example 5 CAS No.: 1254117-55-9 445 Preparation Example 6 CAS No.: 183324-68-7 417

[0051] Note: The CAS number mentioned above is the CAS Registry Number of this compound in the SciFinder database (https: / / scifinder-n.cas.org / ).

[0052] Example 1

[0053] Preparation of a flame-retardant and anti-aging copolyester hot melt adhesive:

[0054] 1. Raw material components:

[0055] Copolyester resin: 50.4 parts. The copolyester resin is composed of aromatic diacid, aliphatic diacid, and aliphatic diol in a molar ratio of 8:2:10. The aromatic diacid is terephthalic acid, the aliphatic diacid is adipic acid, and the aliphatic diol is 1,4-butanediol.

[0056] Halogen-free flame retardant: 20 parts, which is a compound system of ammonium polyphosphate and melamine cyanurate, with a mass ratio of 1.5:1, that is, 12 parts of ammonium polyphosphate and 8 parts of melamine cyanurate;

[0057] Anti-aging agent: 3 parts, which is anti-aging agent 1;

[0058] Tackifying resin: 15 parts, which is hydrogenated rosin glycerol ester;

[0059] Plasticizer: 10 parts, diisononyl phthalate;

[0060] Inorganic filler: 12 parts, nano-calcium carbonate;

[0061] Polyvinyl chloride: 3 parts.

[0062] 2. Preparation method:

[0063] a. Copolyester synthesis: Under a nitrogen atmosphere, terephthalic acid, adipic acid, and 1,4-butanediol were added to a reactor, along with tetrabutyl titanate catalyst (0.04% of the total mass of aromatic and aliphatic diacids). The reaction system was heated to 180°C for esterification for 2 hours until the esterified water was completely distilled off. Subsequently, the temperature was raised to 220-250°C, and polycondensation was carried out under reduced pressure (vacuum degree < 50 Pa) for approximately 3 hours until the intrinsic viscosity of the product reached 0.7 dl / g, yielding the copolyester resin.

[0064] b. Mixing process: The synthesized copolyester resin is fed into a mixer in a molten state (temperature 160℃), and diisononyl phthalate, hydrogenated rosin glycerol ester, halogen-free flame retardant, anti-aging agent 1, polyvinyl chloride and inorganic filler are added in sequence. The mixing process is carried out under a nitrogen atmosphere, the temperature of the mixer is controlled at 170℃, the speed is set to 45 rpm, and the mixing time is 30 minutes, until the components are evenly dispersed and a homogeneous molten mixture is formed.

[0065] c. Molding process: The uniformly mixed molten material is extruded into strips through a twin-screw extruder, cooled with water, and then cut into particles with a diameter of about 2-3 mm by a pelletizer. Finally, it is dried at 80°C for 4 hours to obtain the flame-retardant and anti-aging copolyester hot melt adhesive.

[0066] Examples 2-6

[0067] The preparation of a flame-retardant and anti-aging copolyester hot melt adhesive is carried out by referring to the preparation method of Example 1, except that the anti-aging agent 1 is replaced with anti-aging agent 2-6 in sequence, and the rest is the same as in Example 1.

[0068] Comparative Example 1

[0069] The preparation of a flame-retardant and anti-aging copolyester hot melt adhesive follows the preparation method of Example 1, except that the anti-aging agent 1 is replaced with... (Common anti-aging agents), the rest is the same as in Example 1.

[0070] Comparative Example 2

[0071] The preparation of a flame-retardant and anti-aging copolyester hot melt adhesive is carried out by referring to the preparation method of Example 1, except that the anti-aging agent 1 is replaced with antioxidant 1010 (a commonly used anti-aging agent), and the rest is the same as in Example 1.

[0072] Comparative Example 3

[0073] The preparation of a flame-retardant and anti-aging copolyester hot melt adhesive is carried out by referring to the preparation method of Example 1, except that the anti-aging agent 1 is replaced with antioxidant 1076 (a commonly used anti-aging agent), and the rest is the same as in Example 1.

[0074] Comparative Example 4

[0075] The preparation of a flame-retardant and anti-aging copolyester hot melt adhesive is the same as in Example 1, except that the anti-aging agent 1 is not added.

[0076] Comparative Example 5

[0077] The preparation of a flame-retardant and anti-aging copolyester hot melt adhesive is the same as in Example 1, except that polyvinyl chloride is not added.

[0078] Comparative Example 6

[0079] The preparation of a flame-retardant and anti-aging copolyester hot melt adhesive is the same as in Example 1, except that ammonium polyphosphate is not added.

[0080] Performance testing:

[0081] 1. Flame retardancy rating test: Referring to the UL 94 test method, the flame retardancy rating of a flame retardant and anti-aging copolyester hot melt adhesive prepared in the example and comparative examples was tested, and the data are shown in Table 2.

[0082] 2. Melt viscosity: The melt viscosity of the flame-retardant and anti-aging copolyester hot melt adhesive prepared in the examples and comparative examples was tested according to the test method of GB / T 1633-2000. The data are shown in Table 2.

[0083] 3. Curing time: Referring to the test method of HGT3716-2003, the curing time of a flame-retardant and anti-aging copolyester hot melt adhesive prepared in the test examples and comparative examples was tested, and the data are shown in Table 2.

[0084] 4. Aging Resistance Test: The flame-retardant and anti-aging copolyester hot melt adhesive prepared in the examples and comparative examples was placed in a fluorescent ultraviolet aging chamber (UVB-313 lamp, simulating short-wave ultraviolet light to accelerate aging). The irradiation temperature was 75℃, and the irradiation intensity was 0.71W / (m²). 2•nm), for 4 hours; Condensation stage: temperature 25℃, relative humidity ≥95%, for 4 hours; Number of cycles: 500 cycles (total aging time 4000h), retest melt viscosity, calculate melt viscosity retention rate, data are shown in Table 2.

[0085] Table 2.

[0086] Flame retardant rating Melt viscosity at 180℃, mPa·s Curing time S Melt viscosity retention % Example 1 UL94-V0 1000 5 96 Example 2 UL94-V0 980 6 99 Example 3 UL94-V0 1020 4 97 Example 4 UL94-V0 990 5 95 Example 5 UL94-V0 1010 7 98 Example 6 UL94-V0 970 6 97 Comparative Example 1 UL94-V0 1100 7 80 Comparative Example 2 UL94-V0 1150 5 85 Comparative Example 3 UL94-V0 1120 9 78 Comparative Example 4 UL94-V0 950 7 40 Comparative Example 5 UL94-V0 850 5 91 Comparative Example 6 UL94-HB 960 8 92

[0087] Regarding flame retardancy rating, the comparative examples lacking key flame retardant components (such as ammonium polyphosphate) showed a significant decrease in flame retardancy rating, indicating that this key flame retardant component is crucial for maintaining high flame retardancy performance. In terms of melt viscosity, the examples using the novel anti-aging agent generally exhibited a more moderate and stable range; while the comparative examples using traditional anti-aging agents generally had higher melt viscosities. The comparative examples lacking a certain auxiliary component (such as polyvinyl chloride) had slightly lower melt viscosities than the examples, reflecting the synergistic regulatory effect of the novel anti-aging agent and auxiliary components on the system's flowability. Regarding curing time, the examples showed a more consistent and less volatile curing speed overall. Most importantly, regarding melt viscosity retention (reflecting anti-aging ability), the examples showed significantly higher retention rates than the comparative examples without anti-aging agents or using traditional anti-aging agents, with the comparative example without anti-aging agents showing the lowest retention rate, a particularly significant difference. Meanwhile, the examples with added polyvinyl chloride showed slightly higher retention rates than the comparative examples without this component, indicating that the novel anti-aging agent has a prominent long-lasting anti-aging effect, and that polyvinyl chloride has a slight auxiliary enhancing effect on this effect.

[0088] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A flame-retardant and anti-aging copolyester hot melt adhesive, characterized in that, It is made from raw materials containing the following parts by weight: 30-60 parts copolyester resin, 15-30 parts halogen-free flame retardant, 1-5 parts anti-aging agent, 10-25 parts tackifying resin, 5-15 parts plasticizer, 5-20 parts inorganic filler, and 1-5 parts polyvinyl chloride. The copolyester resin is prepared by polycondensation reaction of aromatic diacid, aliphatic diacid and aliphatic diol, wherein the molar ratio of aromatic diacid to aliphatic diacid is 7-9:3-1. The anti-aging agent is a compound represented by Formula 1: The structure of Equation 1 is as follows: ; R1 in Formula 1 is selected from: hydrogen, cyano, and alkyl groups with 1-5 carbon atoms.

2. The flame-retardant and anti-aging copolyester hot melt adhesive according to claim 1, characterized in that, The aromatic dicarboxylic acid is at least one of terephthalic acid and isophthalic acid; The aliphatic dicarboxylic acid is at least one of adipic acid and sebacic acid; The aliphatic diol is at least one of 1,4-butanediol, 1,6-hexanediol, and ethylene glycol.

3. The flame-retardant and anti-aging copolyester hot melt adhesive according to claim 1, characterized in that, The halogen-free flame retardant is a compound system of at least one of ammonium polyphosphate, aluminum hypophosphite, and dimethyl methylphosphonate with melamine cyanurate, and the mass ratio is 2-1:

1.

4. The flame-retardant and anti-aging copolyester hot melt adhesive according to claim 1, characterized in that, The tackifying resin is at least one of hydrogenated rosin glycerol ester, C5 petroleum resin, and terpene resin.

5. The flame-retardant and anti-aging copolyester hot melt adhesive according to claim 1, characterized in that, The plasticizer is at least one of diisononyl phthalate and dioctyl terephthalate.

6. The flame-retardant and anti-aging copolyester hot melt adhesive according to claim 1, characterized in that, The inorganic filler is at least one of nano-calcium carbonate, talc, and precipitated barium sulfate, with a particle size range of 800-1500 mesh.

7. The flame-retardant and anti-aging copolyester hot melt adhesive according to claim 1, characterized in that, The anti-aging agent is any one of the compounds shown in the following structures: ； ； 。 8. A method for preparing a flame-retardant and anti-aging copolyester hot melt adhesive according to any one of claims 1-7, characterized in that, Includes the following steps: a. Copolyester synthesis: Under nitrogen protection, the aromatic diacid, aliphatic diacid and aliphatic diol are added to a reactor, and a catalyst is added. Esterification reaction is carried out at 180-220℃; then polycondensation reaction is carried out at 220-250℃ under reduced pressure until the intrinsic viscosity of the product reaches 0.6-0.8 dl / g, to obtain copolyester resin; b. Mixing: The copolyester resin is fed into a mixer in a molten state, and the plasticizer, tackifying resin, halogen-free flame retardant, anti-aging agent, polyvinyl chloride and inorganic filler are added in sequence. The mixture is then mixed at 160-180°C for 20-40 minutes until it is homogeneous. c. Molding: The uniformly mixed molten material is extruded, cooled with water, granulated, and dried to obtain the copolyester hot melt adhesive granules.

9. The method for preparing a flame-retardant and anti-aging copolyester hot melt adhesive according to claim 8, characterized in that, The catalyst mentioned in step a is tetrabutyl titanate or antimony acetate, and its addition amount is 0.03%-0.05% of the total mass of aromatic diacids and aliphatic diacids; In step b, the internal mixer rotates at 30-60 rpm.

10. The method for preparing a flame-retardant and anti-aging copolyester hot melt adhesive according to claim 8, characterized in that, Step b is performed under a nitrogen atmosphere.

Images