Reactive hot melt adhesive and preparation method thereof

Abstract

The invention discloses a reactive hot melt adhesive and a preparation method thereof, and relates to the technical field of hot melt adhesives. When the reactive hot melt adhesive is prepared, butyl acrylate, acrylic acid, methyl acrylate, allyl glycidyl ether and diethyl allyl phosphate are subjected to free radical reaction to prepare modified polyacrylate; reacting diethanol amine with acrylamide to synthesize a tertiary amino chain extender; reacting a hindered phenol monomer with pyridol, and then adding aluminum chloride for rearrangement to prepare the hindered phenol sealing agent; the preparation method comprises the following steps: reacting diisocyanate with dihydric alcohol, a tertiary amine chain extender and a coumarin chain extender, adding a hindered phenol sealing agent for blocking, adding modified polyacrylate, and mixing to obtain the reactive hot melt adhesive. The reactive hot melt adhesive prepared by the invention has the advantages of high bonding strength, self-repairing property, flame retardance and aging resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of hot melt adhesives, and specifically to a reactive hot melt adhesive and a preparation method thereof. Background Art

[0002] Hot melt adhesive is a kind of plastic adhesive. Under certain external conditions, its physical form changes with temperature, but its chemical properties remain unchanged and it will not cause environmental pollution, belonging to environmentally friendly chemicals. Traditional hot melt adhesives are mainly EVA hot melt adhesives, which are composed of basic resins, tackifiers, various additives and fillers. As a traditional hot melt adhesive, the main material EVA of EVA hot melt adhesive has good miscibility with other components of the hot melt adhesive, and also has excellent adhesive properties, good flexibility and high and low temperature resistance. However, with the rapid development of technology in the past ten years or so, traditional hot melt adhesives can no longer meet the needs of an increasing variety of new products. Problems such as poor adhesion and easy debonding and aging have emerged. Therefore, it is urgent to develop new hot melt adhesive products with excellent performance.

[0003] Polyurethane hot melt adhesive has the characteristics of good adhesion, not easy to debond and corrosion resistance compared with traditional hot melt adhesives, and is more suitable for various fields. Polyurethane hot melt adhesive is designed to adapt to different materials. It is a kind of adhesive with urethane groups and isocyanate groups in the molecular chain formed by the addition polymerization of polyester or polyether polyols and isocyanates and chain extenders, and has high activity. In addition, it can react with a variety of functional groups containing hydroxyl groups to form interfacial chemical bonds, thus generating extremely strong adhesion properties with various materials. In addition, by adjusting the mixing ratio of polyurethane materials, polyurethane adhesives with different forms of soft segment and hard segment mixing can be formed, so as to prepare adhesives with different properties to meet the bonding of different materials. From the characteristics of the polyurethane materials described above, this structure is a structure formed by the mutual embedding of soft segments and hard segments. Therefore, polyurethane hot melt adhesive has both strong and soft characteristics, and this structure will undergo a cross-linking reaction when encountering moisture, forming a firm and stable adhesive layer with the bonding material, and still maintaining good peel strength at extremely low temperatures, and its low temperature resistance effect far exceeds other types of adhesives. To sum up, polyurethane hot melt adhesive is an adhesive with extremely wide application. At present, polyurethane hot melt adhesive can not only have good adhesion performance with printing materials such as paper and textiles, but also has good adhesion performance with plastics, ceramics, wood, metals, leather and inorganic materials, etc. Therefore, it has wide applications in the fields of printing and packaging, footwear, construction, railway construction, medical equipment and aerospace.

[0004] To facilitate the application of polyurethane hot-melt adhesives, people usually design them to have a relatively small molecular weight during synthesis. As a result, the obtained polyurethane hot-melt adhesives have poor cohesive strength and low initial adhesion strength, often unable to meet the requirements of industrial rapid continuous production for the bonding positioning time. Improving the initial adhesion strength of polyurethane hot-melt adhesives and developing high-initial-adhesion polyurethane hot-melt adhesives can effectively improve the production efficiency in related application fields and promote the further development of related industries. At the same time, isocyanate groups have high reactivity and are prone to react with nucleophilic reagents, which limits their long-term storage and applications in various fields. Summary of the Invention

[0005] The purpose of the present invention is to provide a reactive hot-melt adhesive and its preparation method to solve the problems existing in the prior art.

[0006] To solve the above technical problems, the present invention provides the following technical solutions:

[0007] A reactive hot-melt adhesive, which is prepared by reacting 4,4'-diphenylmethane diisocyanate with polycarbonate diol, hydroxy silicone oil, tertiary amine chain extender, and coumarin-based chain extender, then adding a hindered phenol blocking agent for end-capping, and finally adding a modified polyacrylate and mixing them.

[0008] The tertiary amine chain extender is prepared by reacting diethanolamine with acrylamide.

[0009] The coumarin-based chain extender is 4-methyl-7-hydroxy-8-(1-hydroxyethyl) coumarin.

[0010] The hindered phenol blocking agent is prepared by reacting 3,5-bis(tert-butyl)-4-hydroxybenzoyl chloride with 4-hydroxypyridine and then adding aluminum chloride for rearrangement.

[0011] The modified polyacrylate is prepared by free radical reaction of butyl acrylate, acrylic acid, methyl acrylate, allyl glycidyl ether, and diethyl allyl phosphate.

[0012] As an optimization, the model of the polycarbonate diol is PCDL-T5650J, with a weight average molecular weight of 800, and it is purchased from Guangzhou Haoyi New Material Technology Co., Ltd.

[0013] As an optimization, the model of the hydroxy silicone oil is HSO-30L, with a hydroxy content of 4.25%, and it is purchased from Guangzhou Gibisheng Technology Industry Co., Ltd.

[0014] As an optimization, the structure of the coumarin-based chain extender is:

[0015]

[0016] A preparation method of a reactive hot-melt adhesive, including the following preparation steps:

[0017] (1) Under a nitrogen atmosphere, butyl acrylate and methyl acrylate are mixed evenly. At 40 - 45 °C, azobisisobutyronitrile is added and stirred. Then, azobisisobutyronitrile, allyl glycidyl ether, and diethyl allyl phosphate are added, and stirring continues. A polymerization inhibitor is added and acrylic acid is added dropwise. At 70 - 80 °C, stirring reaction is carried out to obtain a modified polyacrylate;

[0018] (2) Acrylamide, diethanolamine, and pure water are mixed evenly. At room temperature, stirring reaction is carried out. After removing water by rotary evaporation and drying, a tertiary amine chain extender is obtained;

[0019] (3) 4 - hydroxypyridine, sodium hydroxide, and dichloromethane are mixed evenly in an ice - water bath. Under stirring conditions in the ice - water bath, a solution of 3,5 - bis(tert - butyl) - 4 - hydroxybenzoyl chloride is added dropwise. In the ice - water bath, stirring reaction is carried out. Pure water is added, and stirring continues until no bubbles are produced. After extracting and removing the solvent and drying, a hindered phenol pyridine ester is obtained;

[0020] (4) The hindered phenol pyridine ester, anhydrous aluminum chloride, and nitrobenzene are mixed evenly. At 100 - 105 °C, stirring reaction is carried out until no more gas is produced. The temperature is lowered. Under stirring conditions in an ice - water bath, a hydrochloric acid solution is added dropwise. After the addition is complete, stirring continues, and then it is left to stand for liquid - liquid separation. The organic phase is taken, extracted with an aqueous sodium hydroxide solution, the aqueous phase is taken, the pH is adjusted to neutral, filtered by suction, washed, and dried to obtain a hindered phenol blocking agent;

[0021] (5) After vacuum - drying and dehydrating polycarbonate diol and hydroxyl silicone oil, the temperature is lowered to 80 °C. 4,4'-diphenylmethane diisocyanate and dibutyltin dilaurate are added. At 80 - 85 °C, stirring reaction is carried out. After sampling to confirm that the reaction is complete, a tertiary amine chain extender is added. At 80 - 85 °C, stirring reaction is carried out. 4 - methyl - 7 - hydroxy - 8-(1 - hydroxyethyl)coumarin is added. At 85 - 90 °C, stirring reaction is carried out. After sampling to confirm that the reaction is complete, the temperature is lowered to 60 °C. A hindered phenol blocking agent is added. At 65 - 70 °C, stirring reaction is carried out. After sampling to confirm that the reaction is complete, the modified polyacrylate is added and mixed evenly, poured into a mold, and left to stand in a forced - air drying oven to obtain a reactive hot - melt adhesive.

[0022] As an optimization, the polymerization inhibitor described in step (1) is one or more of hydroquinone, hydroquinone monomethyl ether, and p - benzoquinone.

[0023] As an optimization, the modified polyacrylate described in step (1) is prepared by mixing 5-6 parts by mass of butyl acrylate and 3.36-4.03 parts by mass of methyl acrylate evenly under a nitrogen atmosphere, adding 0.03-0.04 parts by mass of azobisisobutyronitrile at 40-45 °C and 400-500 r / min, stirring for 30-40 min, adding 0.03-0.035 parts by mass of azobisisobutyronitrile, 1.86-2.23 parts by mass of allyl glycidyl ether, and 2.32-3.48 parts by mass of diethyl allyl phosphate, continuing to stir for 10-20 min, adding 0.008-0.012 parts by mass of inhibitor, dropping 2.81-3.09 parts by mass of acrylic acid at a rate of 1 drop per second, and reacting at 70-80 °C and 400-500 r / min for 2-3 h after the dropping is completed.

[0024] As an optimization, the tertiary amine chain extender described in step (2) is prepared by mixing 4-5 parts by mass of acrylamide, 5.9-7.4 parts by mass of diethanolamine, and 30-40 parts by mass of pure water evenly, stirring and reacting at room temperature at 200-300 r / min for 5-6 h, removing water by rotary evaporation, and drying in vacuo at 50-60 °C for 8-10 h.

[0025] As an optimization, the reaction process of the tertiary amine chain extender described in step (2) is as follows:

[0026]

[0027] As an optimization, the hindered phenol pyridine ester described in step (3) is prepared by mixing 2-3 parts by mass of 4-hydroxypyridine, 1-1.5 parts by mass of sodium hydroxide, and 15-20 parts by mass of dichloromethane evenly in an ice-water bath, dropping a dichloromethane solution of 45.8-68.7 parts by mass of 15 wt% 3,5-bis(tert-butyl)-4-hydroxybenzoyl chloride at a rate of 1-2 drops per second at 200-300 r / min in the ice-water bath, reacting at 200-300 r / min in the ice-water bath for 8-10 h after the dropping is completed, adding 10-12 parts by mass of pure water, continuing to stir until there are no bubbles, extracting the organic phase with dichloromethane, removing dichloromethane by rotary evaporation, and drying in vacuo at 40-50 °C for 8-10 h.

[0028] As an optimization, the reaction process of the hindered phenol pyridine ester described in step (3) is as follows:

[0029]

[0030] As an optimization, the hindered phenol blocking agent described in step (4) is prepared by mixing 7-8 parts by mass of hindered phenol pyridine ester, 8-9 parts by mass of anhydrous aluminum chloride, and 35-40 parts by mass of nitrobenzene evenly, reacting at 100-105 °C and 700-800 r / min for 3-4 h until no more gas is generated, cooling down, and dropping 30-35 parts of 1 mol / L hydrochloric acid solution at a rate of 1-2 drops per second at 700-800 r / min in an ice-water bath. After the dropping is completed, continue stirring for 30-40 min, then let it stand for 80-100 min to separate layers. Take the organic phase, extract it with 1 mol / L sodium hydroxide aqueous solution, take the aqueous phase, adjust the pH to neutral, filter by suction, wash it with pure water 3-4 times, and dry it in vacuum at 50-60 °C for 8-10 h to obtain.

[0031] As an optimization, the reaction process of the hindered phenol blocking agent described in step (4) is as follows:

[0032]

[0033] As an optimization, the reactive hot-melt adhesive described in step (5) is prepared by mixing 19.18-26.85 parts by mass of polycarbonate diol and 6.39-11.51 parts by mass of hydroxy silicone oil, drying to remove water in vacuum at 120 °C for 2 h, then cooling to 80 °C, adding 20-30 parts by mass of 4,4'-diphenylmethane diisocyanate and 0.1-0.15 parts by mass of dibutyltin dilaurate, reacting at 80-85 °C and 300-400 r / min for 1.5-2 h. After sampling to confirm that the reaction is complete, add 2.82-3.8 parts by mass of tertiary amine chain extender, react at 80-85 °C and 300-400 r / min for 40-50 min, add 2.82-3.43 parts by mass of 4-methyl-7-hydroxy-8-(1-hydroxyethyl)coumarin, react at 85-90 °C and 300-400 r / min for 50-60 min. After sampling to confirm that the reaction is complete, cool to 60 °C, add 14.2-25.57 parts by mass of hindered phenol blocking agent, react at 65-70 °C and 300-400 r / min for 10-12 h. After sampling to confirm that the reaction is complete, add 13.08-20.23 parts by mass of modified polyacrylate and mix evenly, pour it into a mold, and let it stand in a forced-air drying oven at 35-40 °C for 5-6 h to obtain.

[0034] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0035] When preparing the reactive hot melt adhesive, the present invention firstly performs free radical reaction on butyl acrylate, acrylic acid, methyl acrylate, allyl glycidyl ether and allyl diethyl phosphate to prepare modified polyacrylate; reacts diethanolamine with acrylamide to synthesize a tertiary amine chain extender; reacts a hindered phenol monomer with pyridinol and then adds aluminum chloride for rearrangement to prepare a hindered phenol blocking agent; reacts diisocyanate with diol, tertiary amine chain extender and coumarin chain extender, then adds the hindered phenol blocking agent for end-capping, and then adds the modified polyacrylate for mixing to prepare the reactive hot melt adhesive.

[0036] First, butyl acrylate, acrylic acid, methyl acrylate, allyl glycidyl ether, and allyl diethyl phosphate are reacted through free radicals to prepare modified polyacrylates. Acrylic acid and allyl diethyl phosphate provide high initial viscosity in the obtained modified polyacrylates. Acrylic acid contains anionic carboxylic acid groups, which can react with active groups such as hydroxyl groups on the surface of the substrate or form hydrogen bonds to improve the initial viscosity, while allyl diethyl phosphate can improve the bonding strength by forming a complex bond with the metal substrate or undergoing an ester exchange reaction with the hydroxyl groups on the surface of the substrate. Allyl glycidyl ether contains epoxy groups, which can undergo cross-linking reactions with functional groups such as hydroxyl groups and amino groups to improve the bonding strength. At the same time, it can also react with the unblocked isocyanate group to form an oxazolidinone ring structure during high-temperature sizing, which can effectively improve the heat resistance and the mechanical strength of the body. Allyl diethyl phosphate also contains the flame retardant element phosphorus, which can effectively improve the flame retardant effect.

[0037] Secondly, diethanolamine is reacted with acrylamide to synthesize a tertiary amine chain extender. The tertiary amine chain extender, as a weak alkaline group in the main chain of the polyurethane, can form a Lewis acid-base pair with weakly acidic functional groups such as carboxyl groups on the surface of the substrate to improve the initial adhesion. At the same time, the tertiary amine chain extender also has an amide group, which can form more hydrogen bonds and simultaneously improve the bonding strength; the hindered phenol monomer is reacted with pyridinol and then aluminum chloride is added for rearrangement to obtain a hindered phenol blocking agent. The acyl chloride group contained in the hindered phenol monomer undergoes an esterification reaction with 4-hydroxypyridine to obtain a hindered phenol pyridinium ester, and then a Fries rearrangement reaction occurs under the catalysis of aluminum chloride to obtain a hindered phenol blocking agent containing a hydroxyl group. Since a large molecular weight hindered phenol group is connected to the pyridine ring, The urethane bond generated by the reaction of hydroxyl and isocyanate groups is weak and has a low unblocking temperature. The unblocking reaction can fully occur at the gluing temperature of most hot melt adhesives. The hindered phenol structure has good antioxidant properties. At the same time, the pyridine ring has a strong electron attraction ability, which can effectively improve the antioxidant capacity of hindered phenol. The cyclic structure of the pyridine ring has a larger steric hindrance, which can reduce the volatilization and migration of the hindered phenol blocker after unblocking the isocyanate. This steric hindrance can also prevent phenoxy free radicals from capturing hydrogen atoms from the polymer chain and reduce the start of new oxidation cycles. The nitrogen atoms on the pyridine ring can also form hydrogen bonds with the functional groups on the polymer main chain, thereby improving the dispersibility and compatibility of the hindered phenol blocker in the polymer.

[0038] Finally, the diisocyanate is reacted with a diol, a tertiary amine chain extender, and a coumarin-based chain extender, and then blocked with a hindered phenol blocking agent. After that, a modified polyacrylate is added and mixed to obtain a reactive hot melt adhesive. The diol used contains hydroxy silicone oil at the same time. The silicone oxygen alkane segment, as a flexible segment, can effectively improve the toughness and prevent brittle fracture damage of the hot melt adhesive. The silicon element therein can also form a synergistic flame retardant effect with the phosphate group in the modified polyacrylate, further improving the flame retardant performance of the reactive hot melt adhesive; the coumarin-based chain extender contains a coumarin group, which has excellent ultraviolet absorption ability, can effectively prevent ultraviolet aging, and can also have a synergistic effect with the hindered phenol structure to improve the anti-aging performance. At the same time, the coumarin group also has a photo-reversible ability. Under suitable light conditions, it can undergo a reversible photodimerization reaction, thereby endowing the hot melt adhesive with a self-healing effect; the addition of the modified polyacrylate effectively improves the mechanical strength and bonding strength of the reactive hot melt adhesive, and at the same time greatly improves the initial adhesion strength, expanding its application range and improving the construction conditions. When applying glue at high temperature, a deblocking reaction occurs, and the isocyanate group is released. It reacts with functional groups such as epoxy groups, hydroxyl groups, amino groups, and water in the air, further improving the mechanical strength of the body while increasing the bonding strength, and preventing bonding failure caused by the low mechanical strength of the hot melt adhesive itself. Specific Embodiments

[0039] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0040] Hydroquinone is used as the inhibitor in all the following examples and comparative examples.

[0041] Example 1:

[0042] A preparation method of a reactive hot melt adhesive, the preparation method of the reactive hot melt adhesive includes the following preparation steps:

[0043] (1) By mass, in a nitrogen atmosphere, 5 parts of butyl acrylate and 3.36 parts of methyl acrylate are mixed evenly. At 40 °C and 400 r / min, 0.03 part of azobisisobutyronitrile is added, and stirred for 40 min. Then 0.03 part of azobisisobutyronitrile, 1.86 parts of allyl glycidyl ether, and 2.32 parts of allyl diethyl phosphate are added, and stirred continuously for 20 min. 0.008 part of inhibitor is added, and 2.81 parts of acrylic acid are added dropwise at a speed of 1 drop per second. After the addition is completed, the reaction is carried out at 70 °C and 400 r / min for 3 h to obtain a modified polyacrylate;

[0044] (2) Mix 4 parts of acrylamide, 5.9 parts of diethanolamine, and 30 parts of pure water evenly. Stir and react at 200 r / min for 6 h at room temperature. Rotate and evaporate to remove water, and dry in vacuum at 50 °C for 10 h to obtain a tertiary amine chain extender.

[0045] (3) Mix 2 parts of 4-hydroxypyridine, 1 part of sodium hydroxide, and 15 parts of dichloromethane evenly in an ice-water bath. At 200 r / min in the ice-water bath, dropwise add a dichloromethane solution of 45.8 parts of 15 wt% 3,5-bis(tert-butyl)-4-hydroxybenzoyl chloride at a rate of 1 drop per second. After the addition is complete, react at 200 r / min in the ice-water bath for 10 h. Add 10 parts of pure water, continue stirring until there are no bubbles, extract the organic phase with dichloromethane, rotate and evaporate to remove dichloromethane, and dry in vacuum at 40 °C for 10 h to obtain a hindered phenol pyridine ester.

[0046] (4) Mix 7 parts of hindered phenol pyridine ester, 8 parts of anhydrous aluminum chloride, and 35 parts of nitrobenzene evenly. React at 100 °C and 700 r / min for 4 h until no more gas is generated. Cool down, and at 700 r / min in an ice-water bath, dropwise add 30 parts of 1 mol / L hydrochloric acid solution at a rate of 1 drop per second. After the addition is complete, continue stirring for 40 min, then let it stand for 80 min to separate layers. Take the organic phase, extract it with 1 mol / L sodium hydroxide aqueous solution, take the aqueous phase, adjust the pH to neutral, filter by suction, wash with pure water 3 times, and dry in vacuum at 50 °C for 10 h to obtain a hindered phenol blocking agent.

[0047] (5) Mix 19.18 parts of polycarbonate diol and 6.39 parts of hydroxy silicone oil, dry to remove water in vacuum at 120 °C for 2 h, then cool down to 80 °C. Add 20 parts of 4,4'-diphenylmethane diisocyanate and 0.1 part of dibutyltin dilaurate, react at 80 °C and 300 r / min for 2 h. After sampling and confirming that the reaction is complete, add 2.82 parts of tertiary amine chain extender, react at 80 °C and 300 r / min for 50 min, add 2.82 parts of 4-methyl-7-hydroxy-8-(1-hydroxyethyl)coumarin, react at 85 °C and 300 r / min for 60 min. After sampling and confirming that the reaction is complete, cool down to 60 °C, add 14.2 parts of hindered phenol blocking agent, react at 65 °C and 300 r / min for 12 h. After sampling and confirming that the reaction is complete, add 13.08 parts of modified polyacrylate and mix evenly. Pour it into a mold and let it stand in a blast drying oven at 35 °C for 6 h to obtain a reactive hot melt adhesive.

[0048] Example 2:

[0049] A preparation method of a reactive hot melt adhesive, the preparation method of the reactive hot melt adhesive includes the following preparation steps:

[0050] (1) By mass fraction, under a nitrogen atmosphere, 5.5 parts of butyl acrylate and 3.69 parts of methyl acrylate are mixed evenly. At 42 °C and 450 r / min, 0.035 part of azobisisobutyronitrile is added, and stirred for 35 min. Then 0.032 part of azobisisobutyronitrile, 2.04 parts of allyl glycidyl ether, and 2.86 parts of diethyl allyl phosphate are added, and stirring is continued for 15 min. 0.01 part of inhibitor is added, and 2.96 parts of acrylic acid are added dropwise at a rate of 1 drop per second. After the addition is completed, the reaction is carried out at 75 °C and 450 r / min for 2.5 h to obtain modified polyacrylate;

[0051] (2) By mass fraction, 4.5 parts of acrylamide, 6.7 parts of diethanolamine, and 35 parts of pure water are mixed evenly. At room temperature, the mixture is stirred and reacted at 250 r / min for 5.5 h, and the water is removed by rotary evaporation. Then it is vacuum dried at 55 °C for 9 h to obtain a tertiary amine chain extender;

[0052] (3) By mass fraction, 2.5 parts of 4-hydroxypyridine, 1.26 parts of sodium hydroxide, and 18 parts of dichloromethane are mixed evenly in an ice-water bath. In the ice-water bath, at 250 r / min, a dichloromethane solution of 57.2 parts of 15 wt% 3,5-bis(tert-butyl)-4-hydroxybenzoyl chloride is added dropwise at a rate of 1.5 drops per second. After the addition is completed, the reaction is carried out at 250 r / min in the ice-water bath for 9 h. 11 parts of pure water are added, and stirring is continued until there are no bubbles. The organic phase is extracted with dichloromethane, and the dichloromethane is removed by rotary evaporation. Then it is vacuum dried at 45 °C for 9 h to obtain a hindered phenol pyridine ester;

[0053] (4) By mass fraction, 7.5 parts of hindered phenol pyridine ester, 8.5 parts of anhydrous aluminum chloride, and 38 parts of nitrobenzene are mixed evenly. The reaction is carried out at 100 °C and 750 r / min for 3.5 h until no more gas is generated. The temperature is lowered. In the ice-water bath, at 750 r / min, a 32 parts of 1 mol / L hydrochloric acid solution is added dropwise at a rate of 1.5 drops per second. After the addition is completed, stirring is continued for 35 min, and then left to stand for 90 min for stratification. The organic phase is taken, extracted with 1 mol / L aqueous sodium hydroxide solution, the aqueous phase is taken, the pH is adjusted to neutral, filtered by suction, washed 4 times with pure water, and vacuum dried at 55 °C for 9 h to obtain a hindered phenol blocking agent;

[0054] (5) By mass parts, after drying 23.18 parts of polycarbonate diol and 11.51 parts of hydroxy silicone oil under vacuum at 120 °C for 2 h, the temperature is lowered to 80 °C, then 25 parts of 4,4'-diphenylmethane diisocyanate and 0.12 part of dibutyltin dilaurate are added. The reaction is carried out at 85 °C and 350 r / min for 1.5 h. After sampling to confirm the complete reaction, 3.34 parts of a tertiary amine chain extender are added, and the reaction is carried out at 85 °C and 350 r / min for 45 min. Then 3.3 parts of 4-methyl-7-hydroxy-8-(1-hydroxyethyl) coumarin are added, and the reaction is carried out at 85 °C and 350 r / min for 55 min. After sampling to confirm the complete reaction, the temperature is lowered to 60 °C, 19.53 parts of a hindered phenol blocking agent are added, and the reaction is carried out at 65 °C and 350 r / min for 11 h. After sampling to confirm the complete reaction, 16.63 parts of a modified polyacrylate are added and mixed evenly. Then it is poured into a mold and left standing in a forced air drying oven at 35 °C for 5.5 h to obtain a reactive hot melt adhesive.

[0055] Example 3:

[0056] A preparation method of a reactive hot melt adhesive, the preparation method of the reactive hot melt adhesive comprising the following preparation steps:

[0057] (1) By mass parts, in a nitrogen atmosphere, 6 parts of butyl acrylate and 4.03 parts of methyl acrylate are mixed evenly. At 45 °C and 500 r / min, 0.04 part of azobisisobutyronitrile is added, and stirring is carried out for 30 min. Then 0.035 part of azobisisobutyronitrile, 2.23 parts of allyl glycidyl ether, and 3.48 parts of diethyl allyl phosphate are added, and stirring is continued for 20 min. 0.012 part of a polymerization inhibitor is added, and 3.09 parts of acrylic acid are added dropwise at a rate of 1 drop per second. After the addition is completed, the reaction is carried out at 80 °C and 500 r / min for 2 h to obtain a modified polyacrylate.

[0058] (2) By mass parts, 5 parts of acrylamide, 7.4 parts of diethanolamine, and 40 parts of pure water are mixed evenly. At room temperature, stirring reaction is carried out at 300 r / min for 5 h, and water is removed by rotary evaporation. Vacuum drying is carried out at 60 °C for 8 h to obtain a tertiary amine chain extender.

[0059] (3) By mass parts, 3 parts of 4-hydroxypyridine, 1.5 parts of sodium hydroxide, and 20 parts of dichloromethane are mixed evenly in an ice-water bath. In the ice-water bath, at 300 r / min, 68.7 parts of a 15 wt% dichloromethane solution of 3,5-bis(tert-butyl)-4-hydroxybenzoyl chloride are added dropwise at a rate of 2 drops per second. After the addition is completed, the reaction is carried out at 300 r / min in the ice-water bath for 8 h. 12 parts of pure water are added, and stirring is continued until there are no bubbles. The organic phase is extracted with dichloromethane, and dichloromethane is removed by rotary evaporation. Vacuum drying is carried out at 50 °C for 8 h to obtain a hindered phenol pyridine ester.

[0060] (4) Mix 8 parts of hindered phenol pyridine ester, 9 parts of anhydrous aluminum chloride, and 40 parts of nitrobenzene evenly by mass fraction. React at 105 °C and 800 r / min for 3 h until no more gas is produced. Cool down, and in an ice-water bath, at 800 r / min, add 35 parts of 1 mol / L hydrochloric acid solution dropwise at a rate of 2 drops per second. After the addition is complete, continue stirring for 30 min, then let it stand for 100 min to separate layers. Take the organic phase, extract it with 1 mol / L sodium hydroxide aqueous solution, take the aqueous phase, adjust the pH to neutral, filter by suction, wash 4 times with pure water, and dry in vacuum at 60 °C for 8 h to obtain the hindered phenol blocking agent;

[0061] (5) Mix 26.85 parts of polycarbonate diol and 11.51 parts of hydroxy silicone oil by mass fraction. After drying to remove water under vacuum at 120 °C for 2 h, cool down to 80 °C, add 30 parts of 4,4'-diphenylmethane diisocyanate and 0.15 part of dibutyltin dilaurate, react at 85 °C and 400 r / min for 1.5 h. After sampling to confirm the reaction is complete, add 3.8 parts of tertiary amine chain extender, react at 85 °C and 400 r / min for 40 min, add 3.43 parts of 4-methyl-7-hydroxy-8-(1-hydroxyethyl)coumarin, react at 90 °C and 400 r / min for 50 min. After sampling to confirm the reaction is complete, cool down to 60 °C, add 25.57 parts of the hindered phenol blocking agent, react at 70 °C and 400 r / min for 10 h. After sampling to confirm the reaction is complete, add 20.23 parts of modified polyacrylate and mix evenly, pour it into a mold, and let it stand in a blast drying oven at 40 °C for 5 h to obtain the reactive hot melt adhesive.

[0062] Comparative Example 1:

[0063] The difference between the preparation method of the reactive hot melt adhesive in Comparative Example 1 and that in Example 2 lies in the difference in step (1). Modify step (1) as follows: Mix 5.5 parts of butyl acrylate and 3.69 parts of methyl acrylate evenly by mass fraction under a nitrogen atmosphere. At 42 °C and 450 r / min, add 0.035 part of azobisisobutyronitrile, stir for 35 min, add 0.032 part of azobisisobutyronitrile and 2.86 parts of diethyl allyl phosphate, continue stirring for 15 min, add 0.01 part of inhibitor, and add 2.96 parts of acrylic acid dropwise at a rate of 1 drop per second. After the addition is complete, react at 75 °C and 450 r / min for 2.5 h to obtain the modified polyacrylate. The remaining steps are the same as those in Example 2.

[0064] Comparative Example 2:

[0065] The preparation method of the reactive hot melt adhesive of Comparative Example 2 is different from that of Example 2 in step (1). Step (1) is modified as follows: By mass, under a nitrogen atmosphere, 5.5 parts of butyl acrylate and 3.69 parts of methyl acrylate are mixed evenly. At 42 °C and 450 r / min, 0.035 parts of azobisisobutyronitrile are added, and the mixture is stirred for 35 min. Then 0.032 parts of azobisisobutyronitrile and 2.04 parts of allyl glycidyl ether are added, and stirring continues for 15 min. 0.01 part of inhibitor is added, and 2.96 parts of acrylic acid are added dropwise at a rate of 1 drop per second. After the addition is complete, the reaction is carried out at 75 °C and 450 r / min for 2.5 h to obtain a modified polyacrylate. The remaining steps are the same as those in Example 2.

[0066] Comparative Example 3:

[0067] The preparation method of the reactive hot melt adhesive of Comparative Example 3 is different from that of Example 2 in that step (2) is not carried out. Step (5) is modified as follows: By mass, 23.18 parts of polycarbonate diol and 11.51 parts of hydroxy silicone oil are dried to remove water under vacuum at 120 °C for 2 h, and then cooled to 80 °C. 25 parts of 4,4'-diphenylmethane diisocyanate and 0.12 part of dibutyltin dilaurate are added, and the reaction is carried out at 85 °C and 350 r / min for 1.5 h. After sampling to confirm that the reaction is complete, 1.18 parts of ethylene glycol are added, and the reaction is carried out at 85 °C and 350 r / min for 45 min. 3.3 parts of 4-methyl-7-hydroxy-8-(1-hydroxyethyl)coumarin are added, and the reaction is carried out at 85 °C and 350 r / min for 55 min. After sampling to confirm that the reaction is complete, the temperature is cooled to 60 °C, 19.53 parts of hindered phenol blocking agent are added, and the reaction is carried out at 65 °C and 350 r / min for 11 h. After sampling to confirm that the reaction is complete, 16.63 parts of the modified polyacrylate are added and mixed evenly, poured into a mold, and left standing in a blast drying oven at 35 °C for 5.5 h to obtain the reactive hot melt adhesive. The remaining steps are the same as those in Example 2.

[0068] Comparative Example 4:

[0069] The preparation method of the reactive hot melt adhesive of Comparative Example 4 is different from that of Example 2 in step (5). Modify step (5) as follows: By mass, 23.18 parts of polycarbonate diol and 11.51 parts of hydroxyl silicone oil are dried to remove water under vacuum at 120 °C for 2 h, then cooled to 80 °C, 25 parts of 4,4'-diphenylmethane diisocyanate and 0.12 part of dibutyltin dilaurate are added, and the reaction is carried out at 85 °C and 350 r / min for 1.5 h. After sampling to confirm that the reaction is complete, 3.34 parts of a tertiary amine chain extender are added, and the reaction is carried out at 85 °C and 350 r / min for 45 min. 0.93 part of ethylene glycol is added, and the reaction is carried out at 85 °C and 350 r / min for 55 min. After sampling to confirm that the reaction is complete, it is cooled to 60 °C, 19.53 parts of a hindered phenol blocking agent are added, and the reaction is carried out at 65 °C and 350 r / min for 11 h. After sampling to confirm that the reaction is complete, 16.63 parts of a modified polyacrylate are added and mixed evenly, poured into a mold, and left standing in a blast drying oven at 35 °C for 5.5 h to obtain the reactive hot melt adhesive. The remaining steps are the same as those in Example 2.

[0070] Comparative Example 5:

[0071] The preparation method of the reactive hot melt adhesive of Comparative Example 5 is different from that of Example 2 in that steps (3) and (4) are not carried out. Modify step (5) as follows: By mass, 23.18 parts of polycarbonate diol and 11.51 parts of hydroxyl silicone oil are dried to remove water under vacuum at 120 °C for 2 h, then cooled to 80 °C, 25 parts of 4,4'-diphenylmethane diisocyanate and 0.12 part of dibutyltin dilaurate are added, and the reaction is carried out at 85 °C and 350 r / min for 1.5 h. After sampling to confirm that the reaction is complete, 3.34 parts of a tertiary amine chain extender are added, and the reaction is carried out at 85 °C and 350 r / min for 45 min. 3.3 parts of 4-methyl-7-hydroxy-8-(1-hydroxyethyl)coumarin are added, and the reaction is carried out at 85 °C and 350 r / min for 55 min. After sampling to confirm that the reaction is complete, it is cooled to 60 °C, 5.23 parts of 4-hydroxypyridine are added, and the reaction is carried out at 65 °C and 350 r / min for 11 h. After sampling to confirm that the reaction is complete, 16.63 parts of a modified polyacrylate are added and mixed evenly, poured into a mold, and left standing in a blast drying oven at 35 °C for 5.5 h to obtain the reactive hot melt adhesive. The remaining steps are the same as those in Example 2.

[0072] Test Example 1:

[0073] Bonding performance test: The initial adhesion strength of the prepared reactive hot melt adhesive was tested to evaluate its initial adhesion performance, and the final adhesion strength between different substrates was tested to evaluate its bonding performance. The specific test method is as follows:

[0074] Initial adhesion strength test: refer to GB / T 7124-2008 to test the bonding shear strength of the prepared reactive hot melt adhesive. The bonding method is to heat the prepared reactive hot melt adhesive to melt and then apply the adhesive on the substrate. The thickness of the adhesive layer is 0.2mm. After applying the adhesive, pressurize it at 5MPa for 15min, bake it at 80℃ for 5min, and then cool and solidify it for 30min to prepare the sample. The lap shear strength tested is the initial adhesion strength. The substrate used is hard PVC board. Each group is tested 5 times and the average value is recorded.

[0075] Final adhesive strength test: refer to GB / T 7124-2008 to test the bonding shear strength of the prepared reactive hot melt adhesive. The bonding method is to heat and melt the prepared reactive hot melt adhesive and then apply the adhesive on the substrate. The thickness of the adhesive layer is 0.2mm. After applying the adhesive, pressurize it at 5MPa for 15min, bake it at 80℃ for 1h and then cool it. Curing it at room temperature for 7 days to obtain a sample. The lap shear strength tested is the initial adhesive strength. The substrates used are hard PVC board, metal aluminum, stainless steel, and polypropylene board with plasma surface treatment. Each group is tested 5 times, and the average value is recorded.

[0076] The hard PVC board used in this test example was purchased from Suzhou Aokai Polymer Materials Co., Ltd., the stainless steel model was 304 stainless steel, and the polypropylene sheet was purchased from Wuxi Xishan New Materials Technology Co., Ltd.

[0077] The results are shown in Table 1.

[0078] Table 1

[0079]

[0080] From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 5 in Table 1, it can be found that the reactive hot melt adhesive prepared in the present invention has good initial adhesion and high bonding strength.

[0081] By comparing the data in the table, it is shown that the introduction of epoxy groups in the modified polypropionate can not only undergo cross-linking reactions with the unblocked isocyanate groups, but also provide a part of viscosity, which reacts with functional groups such as hydroxyl groups on the surface of the substrate to provide viscosity; at the same time, the introduction of phosphate groups and tertiary amine groups effectively improves the bonding strength. The phosphate groups provide higher viscosity by forming complex bonds with metals or reacting with hydroxyl groups on the surface of the substrate. The tertiary amine groups, as weak alkaline groups, can form Lewis acid-base reactions with hydroxyl groups or carboxyl groups on the surface of the substrate, thereby effectively improving the bonding strength of the hot melt adhesive to these substrates. At the same time, the amide groups on the tertiary amine chain extenders can also provide more viscosity by forming more hydrogen bonds, thereby improving the bonding strength.

[0082] Test Example 2:

[0083] Flame retardancy test: The prepared reactive hot melt adhesive was heated and melted and then poured into a polytetrafluoroethylene mold to cool and form a specimen. It was cured at room temperature for seven days. The limiting oxygen index and UL 94 combustion rating of the prepared reactive hot melt adhesive specimen were tested to evaluate its flame retardancy effect. The specific test methods are as follows:

[0084] Limiting oxygen index test: The limiting oxygen index was tested with an oxygen index instrument according to GB / T 2406.1-2008. The specimen size was 150 mm×10 mm×3 mm. Five specimens were tested in each group and the average value was recorded;

[0085] Vertical burning test: The test was carried out with a vertical-horizontal burning tester according to ASTM D3801-2010. Five specimens were tested in each group and the average value was recorded.

[0086] The results are shown in Table 2.

[0087] Table 2

[0088] Limiting oxygen index UL 94 rating Example 1 35.49％ V-0 Example 2 36.15％ V-0 Example 3 35.88％ V-0 Comparative example 1 35.12％ V-0 Comparative example 2 25.94％ V-2 Comparative example 3 34.17％ V-0 Comparative example 4 35.26％ V-0 Comparative example 5 34.85％ V-0

[0089] From the comparison of the experimental data of Examples 1-3 and Comparative Examples 1-5 in Table 2, it can be found that the reactive hot melt adhesive prepared by the present invention has good flame retardancy.

[0090] Through the comparison of the data in the table, it shows that the addition of diethyl allyl phosphate in the modified polyacrylate effectively improves the flame retardancy of the reactive hot melt adhesive. The flame retardant elements phosphorus, silicon, nitrogen and other elements in it act together to improve the flame retardancy effect.

[0091] Test Example 3:

[0092] Anti-aging and self-healing performance test: First, the tensile strength of the prepared reactive hot melt adhesive was tested, and then the ultraviolet aging test and self-healing test were carried out. The anti-aging performance and self-healing performance were evaluated by the strength retention rate after the ultraviolet aging test and self-healing test. The specific test methods are as follows:

[0093] Tensile strength test: Referring to the standard GB / T 528-2009, the prepared reactive hot melt adhesive was heated and melted and then poured into a polytetrafluoroethylene mold to cool and form a specimen. It was cured at room temperature for seven days. The specimen was a dumbbell-shaped specimen, the width of the tensile part was 4 mm, the thickness was 2 mm, the length was 30 mm, the tensile rate was 100 mm / min, and each group of specimens was tested 5 times repeatedly, and the average value was recorded.

[0094] UV aging test: Prepare the specimens according to the tensile strength test, and then use the FR-1205-QUV UV aging tester to perform artificial accelerated aging on the specimens for 10 days according to the standard of GB / T 16422.3-2022. Then test the tensile strength again and calculate the tensile strength retention rate. Repeat the test 5 times for each group of specimens and record the average value.

[0095] Self-repair test: Prepare the sample with reference to the tensile strength test, use a scalpel to cut a scratch on the middle surface of the sample. The length of the scratch is the width of the sample at that part, and the depth is about 1mm. The scratched sample is alternately irradiated with two different wavelengths of ultraviolet light greater than 300nm and less than 300nm to repair it. The alternation is every 30s, and the total repair time is 12h. The tensile strength is tested again, and the tensile strength retention rate is calculated. Each group of samples is tested 5 times, and the average value is recorded.

[0096] The results are shown in Table 3.

[0097] Table 3

[0098] Tensile strength / MPa Retention rate of ultraviolet aging strength Retention rate of self-healing strength Example 1 24.34 93.48％ 96.48％ Example 2 24.79 94.55％ 97.26％ Example 3 24.15 93.87％ 96.15％ Comparative example 1 13.49 92.14％ 94.66％ Comparative example 2 22.37 91.55％ 94.29％ Comparative example 3 20.45 92.62％ 95.16％ Comparative example 4 19.34 68.24％ 24.86％ Comparative example 5 23.87 77.15％ 91.33％

[0099] From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 5 in Table 3, it can be found that the reactive hot melt adhesive prepared in the present invention has good tensile strength, anti-aging and self-repairing properties.

[0100] By comparing the data in the table, it is shown that the epoxy group introduced into the modified polyacrylate undergoes a cross-linking reaction with the isocyanate after it is unblocked, forming a new cross-linking network, thereby effectively improving the tensile strength of the hot melt adhesive; the tertiary amine group in the tertiary amine chain extender, as a weakly basic group, can form a Lewis acid-base reaction with the acrylic acid group in the modified polyacrylate after introduction, thereby improving the mechanical properties, and the amide group thereon can also form more hydrogen bonds to improve the tensile strength; the coumarin chain extender can effectively improve the tensile strength after being introduced into the polyurethane main chain due to its cyclic structure; in the UV aging test, both the coumarin group and the hindered phenol group showed good anti-aging properties, and at the same time, under the synergistic effect of the two, a better anti-aging effect was provided; in the self-repairing test, the coumarin group also showed excellent light self-repairing properties, and its reversible photodimerization reaction under appropriate lighting conditions gave the hot melt adhesive self-repairing ability, and the decrease in the self-repairing strength retention rate of comparative example 5 was due to the lack of hindered phenol groups, resulting in UV aging during the light repair process.

[0101] The specific embodiments described above further elaborate on the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only for the specific embodiments of the present invention and is not intended to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A reactive hot melt adhesive, characterized in that: The reactive hot melt adhesive is prepared by reacting 4,4'-diphenylmethane diisocyanate with polycarbonate diol and hydroxy silicone oil, tertiary amine chain extender, and coumarin chain extender, adding a hindered phenol blocking agent for end-capping, and then adding modified polyacrylate for mixing; The tertiary amine chain extender is prepared by reacting diethanolamine with acrylamide; The coumarin-based chain extender is 4-methyl-7-hydroxy-8-(1-hydroxyethyl) coumarin; The hindered phenol blocking agent is prepared by reacting 3,5-bis(tert-butyl)-4-hydroxyphenylpropionyl chloride with 4-hydroxypyridine and then adding aluminum chloride for rearrangement; The modified polyacrylate is prepared by subjecting butyl acrylate, acrylic acid, methyl acrylate, allyl glycidyl ether and allyl diethyl phosphate to free radical reaction.

2. A reactive hot melt adhesive according to claim 1, characterized in that: The model of the polycarbonate diol is PCDL-T5650J.

3. A reactive hot melt adhesive according to claim 1, characterized in that: The model of the hydroxy silicone oil is HSO-30L.

4. A method for preparing a reactive hot melt adhesive, characterized in that: The method comprises the following preparation steps: (1) In a nitrogen atmosphere, butyl acrylate and methyl acrylate are mixed uniformly, azobisisobutyronitrile is added at 40-45° C., stirred, azobisisobutyronitrile, allyl glycidyl ether, and allyl diethyl phosphate are added, stirring is continued, a retarder is added and acrylic acid is added dropwise, and the reaction is stirred at 70-80° C. to obtain a modified polyacrylate; (2) uniformly mixing acrylamide, diethanolamine and pure water, stirring to react at room temperature, removing water by rotary evaporation and drying to obtain a tertiary amine chain extender; (3) 4-hydroxypyridine, sodium hydroxide and dichloromethane are mixed uniformly in an ice water bath, 3,5-bis(tert-butyl)-4-hydroxyphenylpropionyl chloride solution is added dropwise under stirring in the ice water bath, the mixture is stirred in the ice water bath for reaction, pure water is added, stirring is continued until there are no bubbles, the solvent is removed by extraction and then dried to obtain hindered phenol pyridine ester; (4) Mix hindered phenol pyridine ester, anhydrous aluminum chloride and nitrobenzene uniformly, stir and react at 100-105° C. until no gas is generated, cool down, add hydrochloric acid solution dropwise in an ice water bath under stirring, continue stirring after the addition is complete, then stand for stratification, take the organic phase, extract with sodium hydroxide aqueous solution, take the aqueous phase, adjust the pH to neutral, filter, wash and dry to obtain a hindered phenol blocking agent; (5) After the polycarbonate diol and hydroxy silicone oil are vacuum dried to remove water, the temperature is lowered to 80°C, 4,4'-diphenylmethane diisocyanate and dibutyltin dilaurate are added, and the mixture is stirred at 80-85°C. After sampling to confirm that the reaction is complete, a tertiary amine chain extender is added, and the mixture is stirred at 80-85°C. After the mixture is sampled to confirm that the reaction is complete, the temperature is lowered to 60°C, a hindered phenol blocking agent is added, and the mixture is stirred at 65-70°C. After sampling to confirm that the reaction is complete, the modified polyacrylate is added and mixed evenly, the mixture is poured into a mold, and the mixture is allowed to stand in a blast drying oven to obtain a reactive hot melt adhesive.

5. The method for preparing a reactive hot melt adhesive according to claim 4, characterized in that: The retarder in step (1) is one or more of hydroquinone, hydroquinone monomethyl ether, and p-benzoquinone.

6. The method for preparing a reactive hot melt adhesive according to claim 4, characterized in that: The modified polyacrylate in step (1) is prepared by uniformly mixing 5 to 6 parts of butyl acrylate and 3.36 to 4.03 parts of methyl acrylate under a nitrogen atmosphere, adding 0.03 to 0.04 parts of azobisisobutyronitrile at 40 to 45° C. and 400 to 500 r / min, stirring for 30 to 40 min, adding 0.03 to 0.035 parts of azobisisobutyronitrile, 1.86 to 2.23 parts of allyl glycidyl ether and 2.32 to 3.48 parts of allyl diethyl phosphate, continuing stirring for 10 to 20 min, adding 0.008 to 0.012 parts of a retarder, and dripping 2.81 to 3.09 parts of acrylic acid at a rate of 1 drop per second. After the dripping is completed, reacting at 70 to 80° C. and 400 to 500 r / min for 2 to 3 hours to obtain the obtained product.

7. The method for preparing a reactive hot melt adhesive according to claim 4, characterized in that: The tertiary amine chain extender in step (2) is prepared by uniformly mixing 4 to 5 parts of acrylamide, 5.9 to 7.4 parts of diethanolamine and 30 to 40 parts of pure water by weight, stirring at 200 to 300 r / min for 5 to 6 hours at room temperature, removing water by rotary evaporation, and vacuum drying at 50 to 60° C. for 8 to 10 hours.

8. The method for preparing a reactive hot melt adhesive according to claim 4, characterized in that: The hindered phenol pyridine ester in step (3) is prepared by mixing 2 to 3 parts of 4-hydroxypyridine, 1 to 1.5 parts of sodium hydroxide and 15 to 20 parts of dichloromethane in an ice water bath, and then dropping 45.8 to 68.7 parts of a 15 wt% dichloromethane solution of 3,5-bis(tert-butyl)-4-hydroxyphenylpropionyl chloride at 200 to 300 r / min at a rate of 1 to 2 drops per second in an ice water bath. After the dropwise addition is completed, the mixture is reacted at 200 to 300 r / min in an ice water bath for 8 to 10 hours, 10 to 12 parts of pure water are added, stirring is continued until there are no bubbles, the organic phase is extracted with dichloromethane, the dichloromethane is removed by rotary evaporation, and vacuum drying is performed at 40 to 50° C. for 8 to 10 hours to obtain the obtained product.

9. The method for preparing a reactive hot melt adhesive according to claim 4, characterized in that: The hindered phenol blocking agent in step (4) is prepared by uniformly mixing 7 to 8 parts of hindered phenol pyridine ester, 8 to 9 parts of anhydrous aluminum chloride and 35 to 40 parts of nitrobenzene by weight, reacting at 100 to 105° C. and 700 to 800 r / min for 3 to 4 hours until no more gas is generated, cooling, and dripping 30 to 35 parts of 1 mol / L hydrochloric acid solution at a rate of 1 to 2 drops per second at 700 to 800 r / min in an ice water bath. After the dripping is completed, stirring is continued for 30 to 40 minutes, followed by standing for 80 to 100 minutes to separate the layers, taking the organic phase, extracting with a 1 mol / L sodium hydroxide aqueous solution, taking the aqueous phase, adjusting the pH to neutral, suction filtering, washing with pure water for 3 to 4 times, and vacuum drying at 50 to 60° C. for 8 to 10 hours to obtain the obtained product.

10. The method for preparing a reactive hot melt adhesive according to claim 4, characterized in that: The reactive hot melt adhesive in step (5) is prepared by vacuum drying 19.18 to 26.85 parts of polycarbonate diol and 6.39 to 11.51 parts of hydroxy silicone oil at 120°C for 2 hours, cooling to 80°C, adding 20 to 30 parts of 4,4'-diphenylmethane diisocyanate and 0.1 to 0.15 parts of dibutyltin dilaurate, reacting at 80 to 85°C and 300 to 400 r / min for 1.5 to 2 hours, sampling to confirm that the reaction is complete, adding 2.82 to 3.8 parts of tertiary amine chain extender, and reacting at 80 to 85°C and 300 to 400 r / min for 40 to 50 minutes. 50min, add 2.82-3.43 parts of 4-methyl-7-hydroxy-8-(1-hydroxyethyl) coumarin, react at 85-90°C, 300-400r / min for 50-60min, take samples to confirm that the reaction is complete, cool to 60°C, add 14.2-25.57 parts of hindered phenol blocking agent, react at 65-70°C, 300-400r / min for 10-12h, take samples to confirm that the reaction is complete, add 13.08-20.23 parts of modified polyacrylate, mix well, pour into a mold, and let stand in a 35-40°C forced air drying oven for 5-6h to obtain the product.

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