CN117402585A - Moisture-curing hot melt adhesive and preparation method thereof - Google Patents

Abstract

The application relates to the field of hot melt adhesives, in particular to a moisture-curing hot melt adhesive and a preparation method thereof. The hot melt adhesive comprises the following components: polyester diol, isocyanate, polypropylene glycol diacrylate, maleic anhydride, tackifying resin, antioxidant, chain extender, defoamer and catalyst; the preparation method comprises the following steps: weighing polyester diol, polypropylene glycol diacrylate and tackifying resin, adding the polyester diol, the polypropylene glycol diacrylate and the tackifying resin into a three-port reactor, heating to melt and stirring; weighing isocyanate, adding the isocyanate into a three-port reactor and stirring; weighing maleic anhydride, adding the maleic anhydride into a three-port reactor, and reducing the temperature after reduced pressure distillation; weighing an antioxidant, a chain extender, a defoaming agent and a catalyst, adding the mixture into a three-port reactor, and then fully reacting to obtain a crude product; curing the crude product under the protection of nitrogen. The quaternary cross-linking network structure is formed by the mutual cross-linking and bonding of the polyester dihydric alcohol, the polypropylene glycol diacrylate, the isocyanate and the maleic anhydride, and meanwhile, the problems of poor weather resistance and poor primary adhesion of polyurethane are solved.

Description

Moisture-curing hot melt adhesive and preparation method thereof

Technical Field

The present application relates to the field of hot melt adhesives, and more particularly, to a moisture-curable hot melt adhesive and a method for preparing the same.

Background

The hot melt adhesive is a plastic adhesive, the physical state of which changes with the change of temperature in a certain temperature range, and the chemical characteristics of which are unchanged, and the hot melt adhesive is nontoxic and tasteless, and belongs to an environment-friendly chemical product. The product is solid, is convenient for packaging, transportation and storage, has no solvent or pollution, and has the advantages of simple production process, high added value, high adhesive strength, high speed and the like.

The polyurethane hot melt adhesive is a kind of hot melt adhesive which is prepared by taking polyurethane resin or prepolymer as a main material and adding various auxiliary agents (such as a catalyst, an antioxidant, a tackifier, a filler and the like). Structurally, polyurethane hot melt adhesives are mainly prepolymers synthesized from isocyanate and polyol as main raw materials. The prepolymer mainly consists of a hard segment and a soft segment, wherein the hard segment mainly refers to carbamic acid, urea bond and the like, the soft segment mainly refers to polyol, the structure determines the toughness, impact resistance, good flexibility and the like of a glue film of a polyurethane hot melt adhesive material, and the prepolymer has the advantages of high peeling strength, good low temperature resistance, elasticity, solvent resistance, fatigue resistance, wear resistance and the like, and can be used for bonding polyurethane sponge, rubber and fabric, rubber and metal, metal and ceramic, wood and rubber and plastic and the like. At present, polyurethane adhesives are rapidly developed, the types of products are increasingly various, the application fields are increasingly wide, and the polyurethane adhesives become one of the fastest-developing adhesives at home and abroad. The moisture-curing polyurethane hot melt adhesive is prepared by using-NCO groups as end capping group prepolymers, heating and melting and sizing the prepolymers between an adherend and a substrate, and cooling and curing the prepolymers to form certain initial adhesion. Then, moisture curing and crosslinking are carried out by the moisture on the substrate and the adherend or the moisture in the surrounding environment, namely, the-NCO group in the polyurethane hot melt adhesive is subjected to chemical reaction with water molecules or other active hydrogen-containing compounds to generate carbamate groups (-NHCOO-), then the carbamate continues to react with the (-NCO) group to generate allophanate (-NHCONH-), and the urea group continues to react with the (-NCO) group to generate biuret structure. Because of the unique mechanism of curing with water, moisture-curing polyurethane hot melt adhesives are becoming increasingly hot-melt polyurethane hot melt adhesives.

However, polyurethane hot melt adhesives still suffer from the following disadvantages:

1. poor initial adhesion; because polyurethane hot melt adhesives rely on isocyanate and polyol to react to form polymers with high molecular weight, the polyurethane hot melt adhesives are difficult to harden in situ at one stroke, and a certain time is often required to fully crosslink the molecules, which results in poor initial adhesion of the polyurethane hot melt adhesive, and are not suitable for occasions where quick curing of the adhesive is required.

2. The weather resistance is poor; in polyurethane hot melt adhesive molecules, a large number of active groups such as hydroxyl groups, isocyanate groups and the like are often present, and under the action of ultraviolet rays, moisture and the like, the active groups can be bonded or hydrolyzed, so that the adhesive performance is reduced. However, if the radical inhibitor is added to increase and decrease the activity of the active group during the curing process, the initial adhesion, the bonding firmness and other properties of the adhesive are adversely affected.

Therefore, in summary, if the defects of poor initial adhesion and poor weather resistance of the existing polyurethane hot melt adhesive can be overcome, a wider market can be provided for the polyurethane hot melt adhesive.

Disclosure of Invention

In order to overcome the defects of poor initial adhesion and poor weather resistance of polyurethane hot melt adhesives in the related art, the application provides a moisture-curing hot melt adhesive and a preparation method thereof, wherein polyester diol, isocyanate, polypropylene glycol diacrylate and maleic anhydride are utilized to form a quaternary cross-linked network, so that the initial adhesion of the hot melt adhesive is increased, and the weather resistance of the hot melt adhesive is also increased.

In a first aspect, the present application provides a moisture curable hot melt adhesive, which adopts the following technical scheme:

the moisture-curing hot melt adhesive comprises the following components in parts by weight:

60-100 parts of polyester dihydric alcohol, 60-100 parts of isocyanate, 20-30 parts of polypropylene glycol diacrylate, 10-15 parts of maleic anhydride, 2-6 parts of tackifying resin, 1-3 parts of antioxidant, 2-5 parts of chain extender, 0.4-0.8 part of defoamer and 0.1-0.3 part of catalyst.

In a specific embodiment, the hydroxyl groups of the polyester diol include aromatic polyester diol or crystalline polyester diol, and the hydroxyl value is 30 to 50mgKOH/g.

In a specific embodiment, the isocyanate comprises toluene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, terephthalene diisocyanate, methylcyclohexyl diisocyanate, dicyclohexylmethane diisocyanate.

In a specific embodiment, the antioxidant comprises any one of PUA102, PUB215, 2, 6-di-tert-butyl-4-methylphenol.

In a specific embodiment, the chain extender comprises any one of 1, 4-butanediol, 1, 6-hexanediol, diethylene glycol, diethylaminoethanol, N-dihydroxyl (diisophenyl) aniline, ethylenediamine.

In a specific embodiment, the tackifying resin comprises any one of a terpene resin, polyvinyl acetate, an epoxy resin, and a rosin glyceride.

In a specific embodiment, the defoamer comprises any of mineral oil, polyether, polydimethylsiloxane, silicone defoamer.

In a specific embodiment, the catalyst comprises any one of stannous octoate, tin tert-butoxide, DMDEE, methyl methacrylate.

In a second aspect, the present application provides a method for preparing a moisture-curable hot melt adhesive, which adopts the following technical scheme:

a preparation method of a moisture-curing hot melt adhesive comprises the following steps:

weighing polyester diol, polypropylene glycol diacrylate and tackifying resin according to parts by weight, sequentially adding the polyester diol, the polypropylene glycol diacrylate and the tackifying resin into a three-port reactor, heating until each component is melted, controlling the rotating speed to be 40-60 r/min, and stirring for 20-30 min;

weighing isocyanate according to parts by weight, adding the isocyanate into a three-port reactor, controlling the rotating speed to be 40-60 r/min, and stirring for 40-60 min;

weighing maleic anhydride according to parts by weight, adding the maleic anhydride into a three-port reactor, controlling the temperature to be 100-105 ℃, performing reduced pressure distillation under the vacuum degree of minus 0.1-minus 0.06MPa for at least 2 hours, and then cooling to below 70 ℃;

introducing helium balance pressure, weighing an antioxidant, a chain extender, a defoaming agent and a catalyst according to parts by weight, adding the mixture into a three-port reactor, and then controlling the temperature to be 80-90 ℃ and the vacuum degree to be minus 0.1-minus 0.06MPa for reacting for 2-3 hours to obtain a crude product;

and (3) placing the crude product into an oven at 80-90 ℃ under the protection of nitrogen to be cured for 7-8 hours, thus obtaining the moisture curing hot melt adhesive.

The application has the following beneficial effects: the quaternary cross-linking network structure is formed by the mutual cross-linking and bonding of the polyester dihydric alcohol, the polypropylene glycol diacrylate, the isocyanate and the maleic anhydride, and meanwhile, the problems of poor weather resistance and poor primary adhesion of polyurethane are solved.

Detailed Description

The present application is described in further detail below with reference to examples.

The field of polyurethane hot melt adhesives is rapidly developed, new technology is replaced day by day, the applicant knows through literature search and self research and development experience that the currently widely used moisture curing polyurethane hot melt adhesive mainly depends on-NCO groups as terminal substituents, the adhesive is applied between an adherend and a substrate after being heated, first cooling and curing are carried out to form certain initial adhesion, then moisture curing and crosslinking are carried out by depending on moisture in the environment, the mechanism is that-NCO groups react with components (such as water molecules) containing active hydrogen to generate-NHCONH-, then-NHCONH-react with-NCO groups to generate structures containing urea groups, and the dehydration condensation reaction of the urea groups structures generates biuret structures, so that crosslinking is completed. However, the applicant found that this hardening reaction needs to be completed gradually, and that before encountering active hydrogen, the components cannot undergo significant crosslinking and curing, and that the force between the components and the substrate and the adherend is small, i.e., the initial adhesion is weak; in addition, although the above-mentioned process of dehydrating and condensing urea groups ensures good adhesion and cohesion after curing the polyurethane hot melt adhesive, the adhesion between the polyurethane hot melt adhesive and a substrate and an adherend is mainly realized by covalent bonds, hydrogen bonds and van der Waals forces, mainly because a plurality of active groups such as ester groups exist in the polyurethane hot melt adhesive molecules at adhesive interfaces, and the groups can bond or decompose themselves under the action of ultraviolet rays, moisture, oxygen and the like to become groups with lower activity, and over time, the adhesion force of the adhesive interfaces is weakened, and even the adhesive layer is completely detached from the substrate/adherend, so that the moisture-cured polyurethane hot melt adhesive has poor weather resistance after curing.

Aiming at the technical problem of weak initial adhesion, some technical personnel in the art modify polyurethane hot melt adhesives, including adding fillers (such as adding nano silicon dioxide), modifying coupling agents (such as modifying silane/titanate coupling agents), improving formulas (such as adding acrylic esters) and the like, but the improvement on initial adhesion and weather resistance is rarely realized at the same time, so the applicant provides a moisture curing hot melt adhesive and a preparation method thereof aiming at the two problems at the same time.

First, the existing components based on polyurethane hot melt adhesives: polyester/polyether diols and isocyanates, the applicant found in the study that polyester/polyether diols and isocyanates can only form a crosslinked structure, and that the crosslinked structure is relatively single, which may be one of the reasons for the relatively weak initial adhesion. Therefore, the applicant finds through a large number of experiments that in the preparation process of the polyurethane hot melt adhesive, when the components are polyester diol and isocyanate, if polypropylene glycol diacrylate is added to cooperate with the polyester diol and the isocyanate, the formation of a crosslinked network is accelerated, and meanwhile, the polypropylene glycol diacrylate is also of a long-chain structure, and in the bonding process of the polyester diol and the isocyanate, soft segments embedded into the polyurethane hot melt adhesive can be penetrated to form a ternary interpenetrating network, so that the initial adhesion of the polyurethane hot melt adhesive is improved; however, the addition of only polypropylene glycol diacrylate, although it can exert the above-mentioned effects, the polyurethane hot melt adhesive also causes the number of active groups to increase because of the complexity of the crosslinked structure of the soft segment itself, the active groups introduced by polypropylene glycol diacrylate are mainly ester groups, different from carboxyl groups and hydroxyl groups, the adhesion force of ester groups and adherends/substrates mainly depends on van der Waals forces and forces such as hydrogen bonds, and it is difficult to form the bonding effect, so that although the initial adhesion force of the polyurethane hot melt adhesive has positive influence, there is a certain defect, possibly causing the polyurethane hot melt adhesive to have poorer weather resistance instead.

For this purpose, the applicant proposes the following solutions: after isocyanate, polyester diol and polypropylene glycol diacrylate are uniformly mixed, heating and adding maleic anhydride under negative pressure, so that ester groups in a polypropylene glycol diacrylate molecular chain and double bonds in maleic anhydride can be subjected to DA reaction, maleic anhydride is grafted on the polypropylene glycol diacrylate molecular chain, the purpose of changing the ester groups into hydroxyl groups is achieved, the possibility of bonding between an adhesive interface and an adherend and a substrate can be increased, the probability of decomposition is reduced, and the weather resistance of the polyurethane hot melt adhesive is improved to a certain extent; similarly, maleic anhydride can react with ester groups originally existing in polyurethane to reduce the possibility of degradation.

In addition, the maleic anhydride contains unsaturated functional groups, so that the maleic anhydride can be inserted into the ternary interpenetrating network under the preparation condition to form a structure similar to a quaternary interpenetrating network structure, and the initial adhesion and solidification of the polyurethane hot melt adhesive are further improved.

Therefore, in summary, the quaternary interpenetrating network structure is formed by the polyester diol, the polypropylene glycol diacrylate, the isocyanate and the maleic anhydride, and meanwhile, the problems of poor weather resistance and poor initial adhesion of polyurethane are optimized.

The present invention is further explained below with reference to specific examples.

Examples

It should be noted that the present application aims to propose a moisture-curable hot melt adhesive with a quaternary penetrating structure, and all the above additives and polymers can be used in the common compounds in the art, except the specific description, for example:

the polyester diol can be aromatic polyester diol or crystalline polyester diol, and the required hydroxyl value is 30-50 mgKOH/g; the isocyanate can be selected from any one of common toluene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, terephthalene diisocyanate, methylcyclohexyl diisocyanate and dicyclohexylmethane diisocyanate; the antioxidant can be any one of commercial PUA102, PUB215 and 2, 6-di-tert-butyl-4-methylphenol; the chain extender can be any one of 1, 4-butanediol, 1, 6-hexanediol, diethylene glycol, diethylaminoethanol, N-dihydroxyl (diisophenyl) aniline and ethylenediamine; the tackifying resin can be any one of terpene resin, polyvinyl acetate, epoxy resin and rosin glyceride; the defoamer can be any one of mineral oil, polyether, polydimethylsiloxane and organosilicon defoamer; the catalyst can be selected from any one of stannous octoate, tin tert-butoxide, DMDEE and methyl methacrylate.

Example 1

The embodiment provides a moisture-curing hot melt adhesive, which is prepared by the following steps:

s1, weighing 6kg of polyester diol, 2kg of polypropylene glycol diacrylate and 0.2kg of tackifying resin, sequentially adding into a three-port reactor, heating until each component is melted, controlling the rotating speed to be 60r/min, and stirring for 20min;

s2, weighing 6kg of isocyanate, adding the isocyanate into a three-port reactor, controlling the rotating speed to be 60r/min, and stirring for 40min;

s3, weighing 1kg of maleic anhydride, adding the maleic anhydride into a three-port reactor, controlling the temperature to be 100 ℃, performing reduced pressure distillation under the vacuum degree of-0.1 MPa for 2 hours, and then cooling to 65 ℃;

s4, introducing helium gas to balance pressure, then weighing 100g of antioxidant, 200g of chain extender, 40g of defoamer and 10g of catalyst, adding into a three-port reactor, and then controlling the temperature to 80 ℃ and the vacuum degree to-0.1 MPa for reaction for 3 hours to obtain a crude product;

s5, placing the crude product in an oven at 80 ℃ for curing for 8 hours under the protection of nitrogen, and obtaining the moisture curing hot melt adhesive.

In the examples herein, the hydroxyl value of the polyester diol is 30mgKOH/g; toluene diisocyanate is selected as isocyanate; the tackifying resin is polyvinyl acetate; the antioxidant is PUB215; the chain extender is ethylenediamine; mineral oil is selected as the defoamer; the catalyst is DMDEE.

Example 2

The embodiment provides a moisture-curing hot melt adhesive, which is prepared by the following steps:

s1, weighing 8kg of polyester diol, 2.5kg of polypropylene glycol diacrylate and 0.4kg of tackifying resin, sequentially adding into a three-port reactor, heating until each component is melted, controlling the rotating speed to be 50r/min, and stirring for 25min;

s2, weighing 8kg of isocyanate, adding the isocyanate into a three-port reactor, controlling the rotating speed to be 50r/min, and stirring for 50min;

s3, weighing 1.3kg of maleic anhydride, adding the maleic anhydride into a three-port reactor, controlling the temperature to be 102 ℃, performing reduced pressure distillation under the vacuum degree of-0.08 MPa for 3 hours, and then cooling to 60 ℃;

s4, introducing helium balance pressure, then weighing 200g of antioxidant, 350g of chain extender, 60g of defoamer and 20g of catalyst, adding into a three-port reactor, and then controlling the temperature at 85 ℃ and the vacuum degree at-0.08 MPa for 2.5h to obtain a crude product;

s5, placing the crude product in an oven at 85 ℃ for curing for 7.5 hours under the protection of nitrogen, and obtaining the moisture curing hot melt adhesive.

In the examples herein, the hydroxyl value of the polyester diol is 41mgKOH/g; the isocyanate is diphenyl methane diisocyanate; the tackifying resin is epoxy resin; the antioxidant is 2, 6-di-tert-butyl-4-methylphenol; the chain extender is diethylene glycol: diethylaminoethanol=2:1 (weight ratio); the defoamer is polydimethylsiloxane; the catalyst is tin tert-butoxide.

Example 3

The embodiment provides a moisture-curing hot melt adhesive, which is prepared by the following steps:

s1, weighing 10kg of polyester diol, 3kg of polypropylene glycol diacrylate and 0.6kg of tackifying resin, sequentially adding into a three-port reactor, heating until each component is melted, controlling the rotating speed to be 40r/min, and stirring for 30min;

s2, weighing 10kg of isocyanate, adding the isocyanate into a three-port reactor, controlling the rotating speed to be 40r/min, and stirring for 60min;

s3, weighing 1.5kg of maleic anhydride, adding the maleic anhydride into a three-port reactor, controlling the temperature to 105 ℃, performing reduced pressure distillation under the vacuum degree of-0.06 MPa for 4 hours, and then cooling to 60 ℃;

s4, introducing helium gas to balance pressure, then weighing 300g of antioxidant, 500g of chain extender, 40-80 g of defoamer and 10-30 g of catalyst, adding the mixture into a three-port reactor, and then controlling the temperature to 90 ℃ and the vacuum degree to be minus 0.06MPa for 2 hours to obtain a crude product;

s5, placing the crude product in a baking oven at 90 ℃ for curing for 8 hours under the protection of nitrogen, and obtaining the moisture curing hot melt adhesive.

In the examples herein, the hydroxyl value of the polyester diol is 50mgKOH/g; the isocyanate is methyl cyclohexyl diisocyanate; the tackifying resin is rosin glyceride; the antioxidant is 2, 6-di-tert-butyl-4-methylphenol; the chain extender is 1, 6-hexanediol; polyether is selected as the defoamer; the catalyst is methyl methacrylate.

Example 4

The difference between this example and example 2 is that in this example, diphenylmethane diisocyanate and isophorone diisocyanate are selected and compounded according to a weight ratio of 3:1.

Comparative example 1

This comparative example differs from example 1 in the absence of maleic anhydride in the components.

Comparative example 2

This comparative example differs from example 1 in the absence of polypropylene glycol diacrylate in the composition.

Performance test

Performance test tests were performed using examples 1 to 4 and comparative examples 1 to 2 as samples. The physical properties of a portion of the samples are shown in table 1; (AL plate is used for both the substrate and the adherend in the detection of shear strength and tensile strength)

The main detection indexes are as follows (PC board is selected for both the base material and the adherend):

1. initial tack performance: the shear strength was measured 10min after the hot melt adhesive was applied by heating at room temperature.

2. High-temperature high-humidity weather resistance: the samples were tested for shear strength at 85℃at 85% RH.

3. Thermal shock resistance: -40 ℃/1h to 85 ℃/1h, and cycling for 20 times, and testing the shear strength of the sample.

The results of the tests of the initial adhesion property, the high-temperature high-humidity weather resistance property and the thermal shock resistance property are shown in Table 2.

TABLE 1

TABLE 2

As can be seen from the results of the examination of table 1, examples 1 to 4 have properties similar to or superior to those of the commercial polyurethane hot melt adhesives; wherein example 4 is preferred, this is probably due to the more excellent formulation composition and choice of parameters for the preparation steps of example 4.

The combination of the test results in table 2 and the performance of the existing polyurethane hot melt adhesive shows that the initial adhesion performance, the weather resistance under high temperature and high humidity and the tolerance under cold and hot impact of examples 1 to 4 are all obviously improved, compared with the existing polyurethane hot melt adhesive, the initial adhesion and the weather resistance are obviously improved, and the test results in comparative examples 1 and 2 are combined, and the maleic anhydride is absent in comparative example 2, so that a ternary interpenetrating network can be formed by means of propylene glycol diacrylate, but the weather resistance is obviously deteriorated due to the introduction of more ester groups; because of the lack of propylene glycol diacrylate in comparative example 2, although ester groups in the molecule can be digested with maleic anhydride, the formation of interpenetrating network is not rapid and thus the initial adhesion is significantly reduced.

In conclusion, the problems of poor weather resistance and poor initial adhesion of polyurethane can be simultaneously optimized only by forming a quaternary cross-linked network structure through the mutual cross-linking bonding of polyester diol, polypropylene glycol diacrylate, isocyanate and maleic anhydride.

The present embodiment is merely illustrative of the present application and is not intended to be limiting, and those skilled in the art, after having read the present specification, may make modifications to the present embodiment without creative contribution as required, but is protected by patent laws within the scope of the claims of the present application.

Claims (9)

1. The moisture-curing hot melt adhesive is characterized by comprising the following components in parts by weight:

60-100 parts of polyester diol, 60-100 parts of isocyanate, 20-30 parts of polypropylene glycol diacrylate, 10-15 parts of maleic anhydride, 2-6 parts of tackifying resin, 1-3 parts of antioxidant, 2-5 parts of chain extender, 0.4-0.8 part of defoamer and 0.1-0.3 part of catalyst.

2. A moisture curable hot melt adhesive according to claim 1, wherein: the hydroxyl group of the polyester diol comprises aromatic polyester diol or crystalline polyester diol, and the hydroxyl value is 30-50 mgKOH/g.

3. A moisture curable hot melt adhesive according to claim 1, wherein: the isocyanate comprises toluene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, terephthalene diisocyanate, methylcyclohexyl diisocyanate and dicyclohexylmethane diisocyanate.

4. A moisture curable hot melt adhesive according to claim 1, wherein: the antioxidant comprises any one of PUA102, PUB215 and 2, 6-di-tert-butyl-4-methylphenol.

5. A moisture curable hot melt adhesive according to claim 1, wherein: the chain extender comprises any one of 1, 4-butanediol, 1, 6-hexanediol, diethylene glycol, diethylaminoethanol, N-dihydroxyl (diisophenyl) aniline and ethylenediamine.

6. A moisture curable hot melt adhesive according to claim 1, wherein: the tackifying resin comprises any one of terpene resin, polyvinyl acetate, epoxy resin and rosin glyceride.

7. A moisture curable hot melt adhesive according to claim 1, wherein: the defoamer comprises any one of mineral oil, polyether, polydimethylsiloxane and organosilicon defoamer.

8. A moisture curable hot melt adhesive according to claim 1, wherein: the catalyst comprises any one of stannous octoate, tin tert-butoxide, DMDEE and methyl methacrylate.

9. The method for preparing the moisture-curable hot melt adhesive according to any one of claims 1 to 8, which is characterized by comprising the following steps:

weighing polyester diol, polypropylene glycol diacrylate and tackifying resin according to parts by weight, sequentially adding the polyester diol, the polypropylene glycol diacrylate and the tackifying resin into a three-port reactor, heating until each component is melted, controlling the rotating speed to be 40-60 r/min, and stirring for 20-30 min;

weighing isocyanate according to parts by weight, adding the isocyanate into a three-port reactor, controlling the rotating speed to be 40-60 r/min, and stirring for 40-60 min;

weighing maleic anhydride according to parts by weight, adding the maleic anhydride into a three-port reactor, controlling the temperature to be 100-105 ℃, performing reduced pressure distillation under the vacuum degree of minus 0.1 to minus 0.06MPa for at least 2 hours, and then cooling to below 70 ℃;

introducing helium balance pressure, weighing an antioxidant, a chain extender, a defoaming agent and a catalyst according to parts by weight, adding the mixture into a three-port reactor, and then controlling the temperature to be 80-90 ℃ and the vacuum degree to be minus 0.1-minus 0.06MPa for reacting for 2-3 hours to obtain a crude product;

and (3) placing the crude product in an oven at 80-90 ℃ under the protection of nitrogen, and curing for 7-8 hours to obtain the moisture-curing hot melt adhesive.