A high-strength fast-curing bio-based hot melt adhesive and preparation method thereof

Abstract

The present invention belongs to the technical field of hot melt adhesive preparation, and particularly relates to a high-strength fast-setting bio-based hot melt adhesive and a preparation method thereof. A dimer acid polymer is prepared using dimer acid, sebacic acid, polyetheramine, ethylenediamine, an antioxidant and a catalyst, and then the dimer acid polymer is mixed with a β-nucleating agent toughened polypropylene / SiO2 nanocomposite and an organic borosiloxane polymer to obtain the high-strength fast-setting bio-based hot melt adhesive. The prepared hot melt adhesive has good mechanical properties, adhesion and self-healing properties.

Description

Technical Field

[0001] The invention belongs to the technical field of hot melt adhesive preparation, and specifically relates to a high-strength fast-curing bio-based hot melt adhesive and a preparation method thereof. Background Art

[0002] Adhesive is a natural or synthetic substance that can temporarily or permanently bond two substances together. The bonding between the surfaces of two objects is caused by the balance between the adhesion between the adhesive and the substrate and the mechanical properties of the adhesive itself. Therefore, adhesive failure is divided into adhesion failure and cohesion failure. In recent years, as the application fields of adhesives have become more and more extensive, traditional adhesives cannot fully meet the application requirements of various fields. Hot melt adhesive is one of the main types of adhesives. It is solid at room temperature. When used, it needs to be heated to a molten state to obtain a certain fluidity so that it can infiltrate the surface of other objects. After cooling, a high-strength bond is formed on the bonding surface. Hot melt adhesive does not require the use of organic solvents during use. Compared with traditional liquid adhesives, it has higher environmental value, so it is also called "green" adhesive.

[0003] The Chinese patent with the announcement number CN109652002B discloses a polyamide hot melt adhesive with high thermal stability and a preparation method thereof, which is prepared from aliphatic dicarboxylic acid, aliphatic dimer acid, aliphatic diamine, alicyclic diamine, polyetheramine and a crosslinking agent. The prepared polyamide hot melt adhesive has good thermal stability and can be widely used in packaging fields with extremely high requirements for thermal stability. The Chinese patent with the announcement number CN115651599B discloses a polyamide hot melt adhesive and its preparation method and application. The polyamide hot melt adhesive is obtained by melt block copolymerization of carboxyl-terminated nylon prepolymer and hydroxyl-terminated polyether polyol, or different types of nylon segment monomers are directly melted and randomly copolymerized to obtain a structural polyamide hot melt adhesive. The prepared polyamide hot melt adhesive has a high amide bond density, and more hydrogen bonds can be formed between molecular chains, which effectively improves its bonding strength and bonding toughness. In addition, due to the introduction of polyether polyol or polyether amine chain segments, it can ensure that the polyamide hot melt adhesive has a lower glass transition temperature, thereby having a lower processing temperature and better processing performance. However, during the use of the hot melt adhesive, cracks may be generated inside due to high temperature, local mechanical stress or load changes, which are difficult to detect in time, thereby reducing the service life. Therefore, the preparation of a hot melt adhesive with self-healing function has become a focus of attention. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention provides a high-strength, fast-curing bio-based hot melt adhesive and a preparation method thereof. A dimer acid polymer is prepared using dimer acid, sebacic acid, polyether amine, ethylenediamine, an antioxidant and a catalyst, and then the dimer acid polymer is mixed with a β-nucleating agent toughened polypropylene / SiO2 nanocomposite and an organic borosiloxane polymer to obtain the high-strength, fast-curing bio-based hot melt adhesive. The prepared hot melt adhesive has good mechanical properties, adhesion and self-healing properties.

[0005] The technical solution adopted by the present invention is as follows:

[0006] A high-strength fast-curing bio-based hot melt adhesive comprises the following raw materials in parts by weight: 220-380 parts of dimer acid, 8-42 parts of sebacic acid, 12-72 parts of polyether amine, 5-12 parts of antioxidant, 0.05-1 part of catalyst, 25-55 parts of ethylenediamine, 10-50 parts of beta-nucleating agent toughened polypropylene / SiO2 nanocomposite, and 8-22 parts of organic borosiloxane polymer.

[0007] Most traditional adhesives rely on petroleum-based raw materials, which not only leads to a large consumption of non-renewable resources, but also often causes environmental pollution problems during production, use and waste gas treatment, such as the emission of volatile organic compounds (VOCs), which poses a potential threat to the health of operators and the ecological environment. In addition, traditional adhesives have many limitations in performance, such as slow solidification speed, which makes it difficult to meet the needs of rapid assembly and molding on modern efficient production lines; limited bonding strength, which is prone to bonding failure when subjected to high temperature, high pressure and complex stress; insufficient heat resistance and weather resistance, which affects the quality and service life of the product. With the enhancement of environmental awareness and the continuous development of production technology, it has become a top priority to develop a bonding hot melt adhesive with fast setting characteristics, high strength, good heat and weather resistance and based on bio-based raw materials.

[0008] Dimer acid is prepared by high-temperature polycondensation of specific vegetable oil acid under specific catalysts and reaction conditions. Its molecular structure has long-chain aliphatic hydrocarbon groups and multiple carboxyl functional groups. The long-chain aliphatic hydrocarbon groups give the hot melt adhesive good flexibility and plasticity, enabling it to adapt to stress deformation caused by temperature changes and shrinkage during use; multiple carboxyl functional groups provide active sites for reactions with other components. During the reaction, they can undergo amidation reaction with the amino group of polyetheramine and form a cross-linked structure with the amino group of ethylenediamine, thereby constructing a macromolecular network skeleton of the hot melt adhesive and affecting the cross-linking density and final performance of the hot melt adhesive. The molecular structure of sebacic acid is relatively short and has high symmetry. Its introduction can adjust the crystallization properties of the hot melt adhesive, control the hardness and melting point range of the hot melt adhesive to a certain extent, and work synergistically with dimer acid to enable the hot melt adhesive to maintain a suitable physical state and bonding performance under different process temperature conditions. Polyetheramine contains polyether segments and amino functional groups. The polyether segments provide good flexibility and low-temperature performance, so that the hot melt adhesive can still maintain a certain bonding ability in a low-temperature environment, avoiding the increase of brittleness due to temperature reduction; the amino group participates in the condensation reaction with dimer acid and sebacic acid, promotes the growth and branching of the molecular chain, and enhances the toughness and adhesion of the hot melt adhesive. The antioxidant adopts a highly efficient hindered phenol antioxidant, which can effectively inhibit the occurrence of oxidation reactions by capturing free radicals during the processing, storage and use of the hot melt adhesive, and prevent the performance degradation of the hot melt adhesive caused by oxidation, such as discoloration, strength reduction, and loss of viscosity, thereby extending the service life and storage period of the hot melt adhesive. The catalyst uses a specific organic metal catalyst, which can significantly increase the reaction rate at a lower concentration and promote the chemical reaction between the raw materials, especially in the process of polycondensation reaction and cross-linking reaction, which can reduce the reaction activation energy, make the reaction more sufficient and efficient, and ensure the uniformity and stability of the molecular structure of the hot melt adhesive. As a key cross-linking agent, ethylenediamine has two amino groups with high reactivity. In the later stage of the reaction, it can quickly undergo cross-linking reaction with the unreacted carboxyl groups on the molecular chain to form a dense three-dimensional network structure. This cross-linking structure not only greatly improves the mechanical strength of the hot melt adhesive, enabling it to withstand high pressure and complex stress during use, but also significantly accelerates the solidification speed of the hot melt adhesive.

[0009] Polypropylene is a semi-crystalline polymer material, a linear polymer formed by the polymerization of propylene monomers under the action of a catalyst. Since it does not contain polar groups, it is a non-polar polymer. Polypropylene as a hot melt adhesive has good mechanical properties, heat resistance and chemical resistance, and has unique bonding properties for low surface energy materials. However, since it is a non-polar polymer, its bonding ability to polar substances is poor, and dimer acid type polyamide resin has excellent bonding to polar substances due to its amide bond. Therefore, blending with dimer acid hot melt adhesive can further broaden the scope of application and improve bonding ability.

[0010] Since hot melt adhesive may cause cracks inside the material under conditions of high temperature, local mechanical stress or load changes during use, and it is difficult to detect in time, thus reducing the service life, the self-healing material organic borosiloxane polymer is introduced into the preparation process of the hot melt adhesive of the present invention, which can self-heal in the early stage of damage, thereby extending the service life of the material. At the same time, since polypropylene and organic borosiloxane polymer are both hydrophobic substances, using them to modify dimer acid type polyamide resin can increase the hydrophobicity of the prepared product, so that it can still maintain adhesion performance in a humid environment.

[0011] Furthermore, the preparation method of the β-nucleating agent is as follows: adding a tetrahydrofuran solution containing terephthaloyl chloride to an aniline solution, reacting for 1-2 hours after the addition is completed, then raising the temperature to 68° C., heating under reflux for 6-8 hours, quenching the reaction with a sodium hydroxide solution after the reaction is completed, cooling and filtering the reaction product, washing it with deionized water for 3-5 times, then washing it with tetrahydrofuran for 3-5 times, and then drying it in a vacuum drying oven at 70-90° C. for 6-8 hours, then recrystallizing it with N,N'-dimethylformamide for 1-2 hours, washing it with ethanol for 3-5 times, and drying it in a vacuum drying oven at 70-90° C. for 8-10 hours to obtain the β-nucleating agent.

[0012] Furthermore, the preparation method of the aniline solution is: adding aniline and triethylamine to a tetrahydrofuran solution, stirring until dissolved; wherein the amount of aniline in the tetrahydrofuran solution is 0.06-0.1 g / mL, and the amount of triethylamine in the tetrahydrofuran solution is 0.065-0.12 g / mL; the preparation method of the tetrahydrofuran solution containing terephthaloyl chloride is: adding terephthaloyl chloride to a tetrahydrofuran solution, stirring until dissolved; wherein the amount of terephthaloyl chloride in the tetrahydrofuran solution is 0.056-0.086 g / mL.

[0013] Polypropylene is a semi-crystalline polymer with five crystal forms, and its performance is affected by the crystal form. Since the β crystal has excellent impact resistance, it can overcome the shortcomings of poor toughness and brittle fracture at low temperatures of polypropylene to a certain extent. Therefore, in this step, N,N'-diphenylterephthalamide β nucleating agent is prepared by the amidation reaction of terephthaloyl chloride and aniline to induce polypropylene to generate β crystal to modify polypropylene.

[0014] Furthermore, the preparation method of the β-nucleating agent toughened polypropylene / SiO2 nanocomposite is as follows: polypropylene, β-nucleating agent and KH550 modified nano-SiO2 are melt-granulated on a twin-screw extruder at 300 rpm and 190-200° C. to obtain;

[0015] SiO2 nanoparticles, as inorganic nanoparticles, can play a role in toughening and strengthening polypropylene. When SiO2 nanoparticles are introduced into polypropylene polymer, they act as stress concentration points and induce microcracks in the surrounding matrix to absorb deformation energy; nanoparticles have a pinning effect at the same time, which slows down and passivates the growth of cracks and prevents them from evolving into large-scale ruptures; in addition, when impact occurs, due to the large contact area between nanoparticles and the matrix, a large number of microcracks generated in the matrix can absorb the impact energy, and a large amount of impact energy will be consumed in the process of further growth of microcracks, thereby improving the impact strength of the material. However, due to the large difference in polarity between nanoparticles and polypropylene, the surface energy is high, and therefore a strong tendency to agglomerate is observed on the surface in the polypropylene matrix, so in this step, nano-SiO2 modified by KH550 is introduced to improve the interface bonding between nanoparticles and the matrix.

[0016] Furthermore, the preparation method of the organic borosiloxane polymer is: placing hydroxy silicone oil in an aluminum beaker, and placing it on a constant temperature magnetic stirrer, raising the temperature to 100-105°C, adding pretreated boric acid thereto in small amounts and multiple times, and after the addition is completed, raising the temperature to 120-125°C, and raising it to 150-155°C with sufficient stirring, and keeping warm for 15-25 minutes to obtain the organic borosiloxane polymer; wherein the pretreatment process of boric acid is: grinding the boric acid in a mortar for 30-40 minutes.

[0017] During use, polymers will inevitably be severely damaged by mechanical forces, which will cause cracks inside the material that are difficult to detect. Spontaneous repair materials can usually undergo physical or chemical reactions at room temperature to crosslink, so the repair process can be completed under mild conditions without human intervention. The intrinsic self-repairing system achieves multiple repairs through the chemical structure of the polymer itself. By introducing reversible dynamic bonds in the molecular structure to give the material dynamic properties, combined with the mobility of the polymer chain segments, the material can spontaneously or under external stimulation to repair structural damage and performance. Therefore, in this step, polyborosiloxane is synthesized by a non-hydrolysis method using terminal hydroxyl polydimethylsiloxane and boric acid as raw materials. Polyborosiloxane has a unique molecular structure, which contains both organic groups -CH3 and inorganic structures Si-O and BO bonds. There are d-π and p-π conjugations in the molecular structure, so it has high high temperature resistance; its molecular chain can rotate around the Si-O bond, and the Si-O-Si bond angle can change accordingly, so the molecular chain has flexibility. The terminal hydroxyl groups and boron hydroxyl groups in its molecular chain form dynamic hydrogen bonds, and the empty orbital of the outermost layer of the boron atom forms dynamic boron-oxygen bonds with the lone pair electrons of oxygen atoms in other molecular chains. At the same time, there is also a dynamic borate ester and covalent bond cross-linking network, which can achieve self-healing of the material at room temperature.

[0018] The present invention also provides a method for preparing a high-strength, fast-curing bio-based hot melt adhesive, comprising the following steps:

[0019] S1. Add dimer acid, sebacic acid, polyetheramine, antioxidant and catalyst into the reaction kettle. Under stirring, the stirring rate is 200-300rpm, the temperature is raised to 100-120°C, the heating rate is 5-10°C / min, and ethylenediamine is added dropwise thereto and the heating is turned off. The dropping time is controlled at 50-70min. After the dropping is completed, the temperature is controlled at 120-140°C and kept warm for 1-2h. Then the temperature is raised to 220-240°C and kept warm for 20-30min. Vacuum polymerization is carried out, the vacuum degree is controlled below -0.092MPa, the vacuum time is 30min, and samples are taken to detect viscosity. After the polymerization is completed, nitrogen is used to The nitrogen gas can prevent the hot melt adhesive from being oxidized by oxygen in the air during the cooling process. After the viscosity is qualified, the material is cooled and discharged, and the cooling rate is controlled to be 5-10°C / min to obtain a dimer acid polymer; wherein the antioxidant is any one of β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, butylated hydroxyanisole, 2,6-di-tert-butyl-4-methylphenol, 2,2'-methylenebis(4-methyl-6-tert-butyl)phenol, N,N'-di(2-naphthyl)-p-phenylenediamine or a mixture of several thereof; the catalyst is any one of the organic metal catalysts stannous octanoate, bismuth isooctanoate, bismuth laurate, and bismuth neodecanoate;

[0020] S2. Add dimer acid polymer, β-nucleating agent toughened polypropylene / SiO2 nanocomposite and organoborosiloxane polymer into the reactor, heat to 100-130°C, stir under vacuum for 60-180min, control the vacuum degree to -0.095MPa, stir the reaction for 1-2h, and discharge the material to obtain the product.

[0021] In step S1, after adding the raw materials of dimer acid, sebacic acid, polyether amine, antioxidant and catalyst into the reactor, the stirring rate is controlled at 200-300 rpm to ensure that the raw materials are fully mixed and uniform, and to prevent uneven reaction due to local concentration differences; the heating rate of 5-10°C / min is obtained through multiple experimental optimization. Although a lower heating rate is conducive to slow melting and preliminary mixing of the raw materials, it will prolong the reaction cycle. Although a higher heating rate can speed up the reaction process, it may cause local overheating, affecting the stability of the raw materials and the uniformity of the reaction.

[0022] After starting to drop ethylenediamine, turn off the heating and use the heat released by the reaction to naturally heat up. The dropping speed of ethylenediamine has a relatively important influence on the stability of the reaction and the performance of the product. If the dropping speed is too fast (such as less than 50 minutes), the reaction system will instantly generate a large amount of heat, causing a sharp rise in temperature, which may trigger side reactions and deteriorate the performance of the product; if the dropping speed is too slow (such as more than 70 minutes), the concentration of ethylenediamine in the reaction system may be unevenly distributed, affecting the uniformity and integrity of the cross-linking reaction, thereby reducing the mechanical strength and solidification speed of the product. At the same time, the temperature is controlled in the temperature range of 120-140°C. Ethylenediamine has a high reaction activity with other components, can form a relatively stable cross-linking structure, and is conducive to heat dissipation and control, avoiding temperature runaway.

[0023] After the addition is complete, the temperature is raised to 120-140°C and kept warm for 1-2 hours, so that ethylenediamine and other components can fully react, further improve the cross-linking structure, and improve the strength and stability of the hot melt adhesive. If the insulation time is too short (such as less than 0.5 hours), the reaction may not be complete, resulting in insufficient cross-linking density of the hot melt adhesive, and reduced mechanical strength and heat resistance; if the insulation time is too long (such as more than 1.5 hours), the molecular chain may be excessively cross-linked, the hot melt adhesive becomes brittle and hard, and the toughness is reduced, affecting its applicability in the casting process.

[0024] Then raising the temperature to 220-240℃ will help further promote the rearrangement and regularization of the molecular chain, and improve the heat resistance and comprehensive performance of the hot melt adhesive. At this temperature, the mobility of the molecular chain is enhanced, and some incompletely reacted functional groups have the opportunity to continue to react, making the molecular structure more stable. The holding time is 20-30 minutes, which is the best time determined by experiments. It can not only ensure the full adjustment of the molecular chain, but also avoid the decomposition of raw materials or performance degradation caused by long-term high temperature.

[0025] When vacuum polymerization is carried out, the vacuum degree is controlled below -0.092MPa. The purpose of vacuuming is to remove small molecules (such as water, unreacted monomers, etc.) and bubbles in the reaction system to improve the purity and density of the hot melt adhesive. A vacuum degree lower than -0.092MPa can ensure the effective removal of small molecules. If the vacuum degree is insufficient, the residual small molecules may affect the performance of the hot melt adhesive, such as reducing the bonding strength and increasing the curing time. The vacuuming time is 30min. During this time, the small molecule impurities in the system can be basically removed. At the same time, the degree of polymerization reaction and the quality of the hot melt adhesive can be preliminarily judged by viscosity detection. Viscosity is an important performance indicator of hot melt adhesive, which is closely related to the length of the molecular chain, molecular weight distribution, cross-linking density, etc. The appropriate viscosity range can ensure the good coating and bonding properties of the hot melt adhesive during use.

[0026] In step S2, when the dimer acid polymer, β-nucleating agent toughened polypropylene / SiO2 nanocomposite and organoborosiloxane polymer are blended, since the dimer acid polymer contains a large number of amide groups, the nitrogen atoms and hydrogen atoms in these amide groups can form hydrogen bonds with atoms with stronger electronegativity, and the presence of silicon-oxygen bonds in the organoborosiloxane polymer can form hydrogen bonds with the molecular chains of the dimer acid polymer during the blending process, which can further improve the mechanical properties of the prepared product.

[0027] The present invention has the following beneficial effects:

[0028] 1. The main raw material dimer acid is derived from renewable plant oil resources and has good biodegradability, which meets the urgent needs of today's society for environmental protection and sustainable development. Compared with traditional petroleum-based adhesives, the present invention can significantly reduce dependence on non-renewable resources, reduce carbon emissions and environmental pollution during use, and help promote the development of the entire industrial chain in an environmentally friendly direction.

[0029] 2. Through the control of the ratio of each raw material and the precise preparation process, especially the efficient cross-linking effect of ethylenediamine and the precise control of reaction temperature and time, the solidification time is further shortened, which significantly improves the production efficiency. For example, in an automated casting production line, the rapid solidification characteristics can greatly shorten the casting cycle and improve the production line's production capacity and economic benefits.

[0030] 3. The synergistic optimization between the components makes the prepared hot melt adhesive have excellent bonding strength and good toughness. It can adapt to the stress changes caused by shrinkage and deformation during use, avoid bonding failure due to brittle fracture, and have a certain self-healing property at room temperature without external force, which can effectively extend the service life of the adhesive and reduce production costs and replacement frequency.

[0031] 4. Through detailed provisions of key process parameters such as the amount of each raw material, the order of addition, the reaction temperature, time, vacuum degree and stirring rate, the preparation process has a high degree of precise controllability and good repeatability, and can stably produce hot melt adhesive products with consistent performance and reliable quality, which is conducive to standardized production and quality control in large-scale industrial production, and reduces the scrap rate and cost fluctuations in the production process. DETAILED DESCRIPTION

[0032] The following will be combined with the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0033] The dimer acid (industrial product, monoacid content 3%, dimer content 85%, trimer content 12%, relative molecular weight 560) used in the present invention was purchased from Jinan Zhuobang Economic and Trade Co., Ltd., sebacic acid (chemically pure), polyetheramine (D-400), terephthaloyl chloride (chemically pure), aniline (chemically pure), triethylamine (chemically pure) were purchased from Aladdin Reagent, ethylenediamine (chemically pure) was purchased from Tianjin Tianli Chemical Reagent Co., Ltd., polypropylene (isotactic polypropylene, F401, melt index 2.5g / 10min, isotacticity 95%) was purchased from Yangzi Petrochemical Company, KH550 modified nano-SiO2 (average particle size 20nm, specific surface area 230m 2 / g) was purchased from Ningbo Jinlei Nanomaterial Co., Ltd., tetrahydrofuran (chemically pure) was purchased from Sinopharm Chemical Reagent Co., Ltd., hydroxy silicone oil (analytical pure, 2.4%) was purchased from Changzhou Juyou New Material Technology Co., Ltd., and boric acid (analytical pure) was purchased from Tianjin Hengxing Chemical Reagent Manufacturing Co., Ltd. All reagents were commercially available.

[0034] Embodiment 1

[0035] A high-strength fast-curing bio-based hot melt adhesive comprises the following raw materials in parts by weight: 320 parts of dimer acid, 20 parts of sebacic acid, 55 parts of polyether amine, 6 parts of antioxidant, 0.1 part of catalyst, 33 parts of ethylenediamine, 25 parts of beta-nucleating agent toughened polypropylene / SiO2 nanocomposite, and 12 parts of organic borosiloxane polymer.

[0036] The preparation method of the β-nucleating agent is as follows: 60 parts by weight of a tetrahydrofuran solution containing terephthaloyl chloride is added dropwise to 60 parts by weight of an aniline solution, and the reaction is carried out for 1.5 hours after the addition is completed, and then the temperature is increased to 68° C., and the reaction is refluxed under heating for 8 hours. After the reaction is completed, the reaction is quenched by a sodium hydroxide solution, and the reaction product is cooled and filtered, washed with deionized water 4 times and then with tetrahydrofuran 4 times, and then placed in a vacuum drying oven at 80° C. for 7 hours, and then recrystallized with N,N'-dimethylformamide for 1.5 hours, and the crystals are filtered out and washed with ethanol 4 times, and placed in a vacuum drying oven at 80° C. for 10 hours to obtain the β-nucleating agent.

[0037] The preparation method of the aniline solution is as follows: adding aniline and triethylamine to a tetrahydrofuran solution and stirring until the mixture is dissolved; wherein the amount of aniline in the tetrahydrofuran solution is 0.08 g / mL, and the amount of triethylamine in the tetrahydrofuran solution is 0.1 g / mL; the preparation method of the tetrahydrofuran solution containing terephthaloyl chloride is as follows: adding terephthaloyl chloride to a tetrahydrofuran solution and stirring until the mixture is dissolved; wherein the amount of terephthaloyl chloride in the tetrahydrofuran solution is 0.065 g / mL.

[0038] The preparation method of the β-nucleating agent toughened polypropylene / SiO2 nanocomposite is as follows: 85 parts by weight of polypropylene, 1.2 parts by weight of β-nucleating agent and 6 parts by weight of KH550 modified nano-SiO2 are melt-granulated on a twin-screw extruder at 300 rpm and 190-200° C. to obtain the composite;

[0039] Among them, the preparation method of the organic borosiloxane polymer is: 68 parts by weight of hydroxyl silicone oil are placed in an aluminum beaker, and the beaker is placed on a constant temperature magnetic stirrer, and the temperature is raised to 105°C, and 1.5 parts by weight of pretreated boric acid are added thereto in small amounts and multiple times, and the addition is divided into 5 times, each time with an interval of 15 minutes. After the addition is completed, the temperature is raised to 125°C, and then raised to 155°C with sufficient stirring, and kept warm for 20 minutes to obtain an organic borosiloxane polymer; wherein, the pretreatment process of boric acid is: the boric acid is placed in a mortar and ground for 35 minutes.

[0040] A method for preparing a high-strength, fast-curing bio-based hot melt adhesive comprises the following steps:

[0041] S1. Weigh each raw material according to the above weight parts for standby use; add dimer acid, sebacic acid, polyether amine, antioxidant and catalyst into the reactor, under stirring, the stirring speed is 250rmp, the temperature is raised to 110°C, the heating rate is 8°C / min, ethylenediamine is added dropwise thereto and the heating is turned off, the dropping time is controlled at 60min, and the temperature is controlled at 130°C after the dropwise addition is completed, and the temperature is kept warm for 1.5h, and then the temperature is raised to 230°C, and the temperature is kept warm for 30min, and vacuum polymerization is carried out, the vacuum degree is controlled below -0.092MPa, and the vacuum time is 30min, and the viscosity is sampled and tested at the same time; after the polymerization is completed, nitrogen is used to break the air, and after the viscosity is qualified, the temperature is lowered and the material is discharged, and the cooling rate is 8°C / min to obtain a dimer acid polymer; wherein the antioxidant is butylated hydroxyanisole; the catalyst is an organic metal catalyst stannous octoate;

[0042] S2. Add dimer acid polymer, β-nucleating agent toughened polypropylene / SiO2 nanocomposite and organoborosiloxane polymer into the reactor, heat to 120°C, stir under vacuum for 120min, control the vacuum degree at -0.095MPa, stir and react for 2h, and discharge to obtain the product.

[0043] Embodiment 2

[0044] Compared with the first embodiment, this embodiment has the following differences:

[0045] A high-strength fast-curing bio-based hot melt adhesive comprises the following raw materials in parts by weight: 220 parts of dimer acid, 8 parts of sebacic acid, 12 parts of polyether amine, 5 parts of antioxidant, 0.05 parts of catalyst, 25 parts of ethylenediamine, 10 parts of beta-nucleating agent toughened polypropylene / SiO2 nanocomposite, and 8 parts of organic borosiloxane polymer.

[0046] In the preparation process of the β-nucleating agent, 45 parts by weight of a tetrahydrofuran solution containing terephthaloyl chloride is added dropwise to 45 parts by weight of an aniline solution. After the addition is completed, the reaction is carried out for 1 hour, and then the temperature is increased to 68° C. and heated under reflux for 6 hours. After the reaction is completed, the reaction is quenched by a sodium hydroxide solution, and the reaction product is cooled and filtered, washed with deionized water 3 times and then with tetrahydrofuran 3 times, and then placed in a vacuum drying oven at 70° C. for 6 hours, and then recrystallized with N,N'-dimethylformamide for 1 hour, and the crystals are filtered out and washed with ethanol 3 times, and placed in a vacuum drying oven at 70° C. for 8 hours to obtain the β-nucleating agent.

[0047] Among them, in the aniline solution, the amount of aniline in the tetrahydrofuran solution is 0.06 g / mL, and the amount of triethylamine in the tetrahydrofuran solution is 0.065 g / mL; in the preparation process of the tetrahydrofuran solution containing terephthaloyl chloride, the amount of terephthaloyl chloride in the tetrahydrofuran solution is 0.056 g / mL.

[0048] In the preparation process of the β-nucleating agent toughened polypropylene / SiO2 nanocomposite, 65 parts by weight of polypropylene, 0.8 parts by weight of β-nucleating agent and 4 parts by weight of KH550 modified nano-SiO2 are melt-granulated on a twin-screw extruder at 300 rpm and 190-200° C. to obtain the composite.

[0049] In the preparation process of the organic borosiloxane polymer, 52 parts by weight of hydroxy silicone oil are placed in an aluminum beaker, and placed on a constant temperature magnetic stirrer, the temperature is raised to 100°C, and 0.8 parts by weight of pretreated boric acid are added thereto in small amounts and multiple times. After the addition is completed, the temperature is raised to 120°C, and then raised to 150°C with sufficient stirring, and kept warm for 15 minutes to obtain an organic borosiloxane polymer; wherein the pretreatment process of boric acid is: grinding the boric acid in a mortar for 30 minutes.

[0050] A method for preparing a high-strength, fast-curing bio-based hot melt adhesive comprises the following steps:

[0051] S1. Weigh each raw material according to the above weight parts for standby; add dimer acid, sebacic acid, polyether amine, antioxidant and catalyst into the reactor, under stirring, stir at a rate of 200rmp, heat to 100°C, and heat at a rate of 5°C / min, then drop ethylenediamine therein and turn off the heating, the dropping time is controlled at 50min, and after the dropwise addition is completed, the temperature is controlled at 120°C, and the temperature is kept for 1h, and then the temperature is increased to 220°C, and the temperature is kept for 20min, and vacuum polymerization is carried out, the vacuum degree is controlled below -0.092MPa, and the vacuum time is 30min, and the viscosity is sampled and tested at the same time; after the polymerization is completed, nitrogen is used to break the air, and after the viscosity is qualified, the temperature is lowered and the material is discharged, and the cooling rate is 5°C / min to obtain a dimer acid polymer;

[0052] S2. Add dimer acid polymer, β-nucleating agent toughened polypropylene / SiO2 nanocomposite and organoborosiloxane polymer into the reactor, heat to 100°C, stir under vacuum for 60min, control the vacuum degree at -0.095MPa, stir the reaction for 1h, and discharge the material to obtain the product.

[0053] Embodiment 3

[0054] Compared with the first embodiment, this embodiment has the following differences:

[0055] A high-strength fast-curing bio-based hot melt adhesive comprises the following raw materials in parts by weight: 380 parts of dimer acid, 42 parts of sebacic acid, 72 parts of polyether amine, 12 parts of antioxidant, 1 part of catalyst, 55 parts of ethylenediamine, 50 parts of beta-nucleating agent toughened polypropylene / SiO2 nanocomposite, and 22 parts of organic borosiloxane polymer.

[0056] In the preparation process of the β-nucleating agent, 85 parts by weight of a tetrahydrofuran solution containing terephthaloyl chloride is added dropwise to 85 parts by weight of an aniline solution. After the addition is completed, the reaction is carried out for 2 hours, and then the temperature is increased to 68° C. and heated under reflux for 8 hours. After the reaction is completed, the reaction is quenched by a sodium hydroxide solution, and the reaction product is cooled and filtered, washed with deionized water 5 times and then with tetrahydrofuran 5 times, and then placed in a vacuum drying oven at 90° C. for 8 hours, and then recrystallized with N,N'-dimethylformamide for 2 hours, and the crystals are filtered out and washed with ethanol 5 times, and placed in a vacuum drying oven at 90° C. for 10 hours to obtain the β-nucleating agent.

[0057] Among them, in the aniline solution, the amount of aniline in the tetrahydrofuran solution is 0.1 g / mL, and the amount of triethylamine in the tetrahydrofuran solution is 0.12 g / mL; in the preparation process of the tetrahydrofuran solution containing terephthaloyl chloride, the amount of terephthaloyl chloride in the tetrahydrofuran solution is 0.086 g / mL.

[0058] In the preparation process of the β-nucleating agent toughened polypropylene / SiO2 nanocomposite, 100 parts by weight of polypropylene, 1.5 parts by weight of β-nucleating agent and 9 parts by weight of KH550 modified nano-SiO2 are melt-granulated on a twin-screw extruder at 300 rpm and 190-200° C. to obtain the composite.

[0059] In the preparation process of the organic borosiloxane polymer, 72 parts by weight of hydroxy silicone oil are placed in an aluminum beaker, and placed on a constant temperature magnetic stirrer, and the temperature is raised to 105°C. 1.5 parts by weight of pretreated boric acid are added thereto in small amounts and multiple times. After the addition is completed, the temperature is raised to 125°C, and then raised to 155°C with sufficient stirring, and kept warm for 25 minutes to obtain an organic borosiloxane polymer; wherein the pretreatment process of boric acid is: grinding the boric acid in a mortar for 40 minutes.

[0060] A method for preparing a high-strength, fast-curing bio-based hot melt adhesive comprises the following steps:

[0061] S1. Weigh each raw material according to the above weight parts for standby use; add dimer acid, sebacic acid, polyether amine, antioxidant and catalyst into the reactor, under stirring, stir at a rate of 300rmp, heat to 120°C, and heat at a rate of 10°C / min, then drop ethylenediamine therein and turn off the heating, the dropping time is controlled at 70min, and after the dropwise addition is completed, the temperature is controlled at 140°C and kept warm for 2h, then the temperature is raised to 240°C and kept warm for 30min, and vacuum polymerization is carried out, the vacuum degree is controlled below -0.092MPa, the vacuum time is 30min, and the viscosity is sampled and tested at the same time; after the polymerization is completed, nitrogen is used to break the air, and after the viscosity is qualified, the material is cooled and discharged, and the cooling rate is 10°C / min to obtain a dimer acid polymer;

[0062] S2. Add dimer acid polymer, β-nucleating agent toughened polypropylene / SiO2 nanocomposite and organoborosiloxane polymer into the reactor, heat to 130°C, stir under vacuum for 180min, control the vacuum degree at -0.095MPa, stir and react for 2h, and discharge to obtain the product.

[0063] Comparative Example 1

[0064] Compared with Example 1, in this comparative example, no organoborosiloxane polymer is added during the preparation of the hot melt adhesive, and the rest is referred to Example 1, as follows:

[0065] A high-strength fast-curing bio-based hot melt adhesive comprises the following raw materials in parts by weight: 320 parts of dimer acid, 20 parts of sebacic acid, 55 parts of polyether amine, 6 parts of antioxidant, 0.1 part of catalyst, 33 parts of ethylenediamine, and 25 parts of beta-nucleating agent toughened polypropylene / SiO2 nanocomposite.

[0066] A method for preparing a high-strength, fast-curing bio-based hot melt adhesive comprises the following steps:

[0067] S1, referring to step S1 of the method for preparing high-strength fast-curing bio-based hot melt adhesive in Example 1;

[0068] S2. Add dimer acid polymer and β-nucleating agent toughened polypropylene / SiO2 nanocomposite into the reactor, heat to 120°C, stir under vacuum for 120min, control the vacuum degree at -0.095MPa, stir and react for 2h, and discharge to obtain the product.

[0069] The rest is as per Example 1.

[0070] Comparative Example 2

[0071] Compared with Example 1, this comparative example does not add β-nucleating agent to toughen the polypropylene / SiO2 nanocomposite during the preparation of the hot melt adhesive, and the rest is referred to Example 1, as follows:

[0072] A high-strength fast-curing bio-based hot melt adhesive comprises the following raw materials in parts by weight: 320 parts of dimer acid, 20 parts of sebacic acid, 55 parts of polyether amine, 6 parts of antioxidant, 0.1 part of catalyst, 33 parts of ethylenediamine, and 12 parts of organic borosiloxane polymer.

[0073] A method for preparing a high-strength, fast-curing bio-based hot melt adhesive comprises the following steps:

[0074] S1, referring to step S1 of the method for preparing high-strength fast-curing bio-based hot melt adhesive in Example 1;

[0075] S2. Add the dimer acid polymer and the organoborosiloxane polymer into the reactor, heat to 120° C., stir under vacuum for 120 min, control the vacuum degree to -0.095 MPa, stir and react for 2 h, and discharge the material to obtain the product.

[0076] Comparative Example 3

[0077] Compared with Example 1, this comparative example does not add β-nucleating agent to toughen polypropylene / SiO2 nanocomposite and organoborosiloxane polymer during the preparation of hot melt adhesive, and the rest is referred to Example 1, as follows:

[0078] A high-strength fast-curing bio-based hot melt adhesive comprises the following raw materials in parts by weight: 320 parts of dimer acid, 20 parts of sebacic acid, 55 parts of polyether amine, 6 parts of antioxidant, 0.1 part of catalyst and 33 parts of ethylenediamine.

[0079] The dimer acid polymer obtained in step S1 during the preparation of a high-strength, fast-curing bio-based hot melt adhesive is the hot melt adhesive.

[0080] Related tests:

[0081] Melt viscosity test: The melt viscosity of the sample was tested using a Brookfield DV-E rotational viscometer. The samples prepared in each embodiment and comparative example (10.0 g for each sample) were weighed for testing. During the test, a rotor of model S27 was selected, the temperature was controlled at 200°C, and the rotation rate was continuously adjusted so that the test value was within the linear range of 20% to 90%. The measured value was recorded after stabilization. The test results are shown in Table 1.

[0082] Tensile strength and elongation test: The samples prepared in each embodiment and comparative example were made into dumbbell shapes according to standard ASTM-D638-2003, and the tensile properties were tested after measuring the thickness. The test results are shown in Table 1.

[0083] Table 1 Melt viscosity, tensile strength and elongation test results

[0084]

[0085] Tensile shear strength test: The samples prepared in each embodiment and comparative example were used for bonding between wooden boards and between PE boards and PET boards. After two groups of samples were prepared, the tensile shear strength between the samples in the two groups of samples and different substrates was tested with reference to GB / T 7124-2008 "Determination of tensile shear strength of adhesives (rigid material to rigid material)". The tensile rate was 10 mm / min. The test results are shown in Table 2, wherein the higher the tensile shear strength, the higher the bonding strength of the hot melt adhesive to the substrate and the better the bonding performance.

[0086] Weather resistance test: The sample in the tensile shear strength test was heated to 80°C and kept warm for 500 hours. The tensile shear strength was tested with reference to GB / T7124-2008 "Determination of tensile shear strength of adhesives (rigid material to rigid material)". The tensile rate was 10 mm / min. The test results are shown in Table 2. The smaller the decrease in tensile shear strength before and after high temperature treatment, the better the weather resistance of the hot melt adhesive.

[0087] Table 2 Tensile shear strength test results

[0088]

[0089] Open time test method: With reference to HG / T 3716-2003 Determination of open time of hot melt adhesive, the samples prepared in each embodiment and comparative example were tested. The test was carried out in an environment with a temperature of 23°C ± 2°C and a relative humidity of 50% ± 5%. The hot melt adhesive melt temperature was 150°C ± 2°C, and the test interval was 5s. The test results are shown in Table 3, wherein the shorter the open time, the better the quick-drying property of the hot melt adhesive.

[0090] Table 3 Opening time test results

[0091]

[0092] Self-repairing performance test: The sample prepared in Example 1 was made into a dumbbell shape according to the standard ASTM-D638-2003, and a double-layer blade was prepared using a utility blade (100×18×0.5 mm). A weight of 100 g was placed on the double blade to control the applied force, and a cut was produced under the action of gravity. The repair of the scratches on the sample surface was observed using a LEXTOLS4000 laser confocal microscope produced by OLYMPUS of Japan. The test results are shown in Table 4, where the average value of the absolute value of the height difference at each point is used to characterize the surface roughness of the sample, and S α express.

[0093] Table 4 Self-repair performance test results

[0094]

[0095] It can be seen from the test results in Table 4 that the cuts produced on the sample prepared in Example 1 increased the roughness from 0.245 μm to 0.652 μm, and the roughness decreased to 0.522 μm after repairing at room temperature for 60 minutes, indicating that the sample prepared in Example 1 has certain self-healing properties at room temperature.

[0096] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0097] Although the embodiments of the present application have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A high-strength, fast-curing bio-based hot melt adhesive, characterized in that: The invention comprises the following raw materials in parts by weight: 220-380 parts of dimer acid, 8-42 parts of sebacic acid, 12-72 parts of polyetheramine, 5-12 parts of antioxidant, 0.05-1 parts of catalyst, 25-55 parts of ethylenediamine, 10-50 parts of beta nucleating agent toughened polypropylene / SiO2 nanocomposite, and 8-22 parts of organic borosiloxane polymer; The method comprises the following preparation steps: S1. Add dimer acid, sebacic acid, polyetheramine, antioxidant and catalyst into a reaction kettle, raise the temperature to 100-120°C under stirring, then drop ethylenediamine into the reaction kettle and turn off the heating. After the dropwise addition is completed, control the temperature at 120-140°C, keep it warm for 1-2h, then raise the temperature to 220-240°C, keep it warm for 20-30min, perform vacuum polymerization, and after the polymerization is completed, use nitrogen to break the air, cool down and discharge the material to obtain a dimer acid polymer; S2. Add dimer acid polymer, β-nucleating agent toughened polypropylene / SiO2 nanocomposite and organoborosiloxane polymer into a reaction kettle, heat to 100-130° C., dehydrate under vacuum for 60-180 min under stirring, control the vacuum degree, stir the reaction for 1-2 h, and discharge the material to obtain the product.

2. The high-strength, fast-curing bio-based hot melt adhesive according to claim 1, characterized in that: The preparation method of the β-nucleating agent is as follows: adding a tetrahydrofuran solution containing terephthaloyl chloride to an aniline solution, reacting for 1-2 hours after the addition is completed, then increasing the temperature and heating under reflux for 6-8 hours, quenching the reaction with a sodium hydroxide solution after the reaction is completed, cooling and filtering the reaction product, washing, drying, recrystallizing, secondary washing, and secondary drying to obtain the β-nucleating agent.

3. The high-strength, fast-curing bio-based hot melt adhesive according to claim 2, characterized in that: The preparation method of the aniline solution is: adding aniline and triethylamine into a tetrahydrofuran solution and stirring until dissolved; the preparation method of the tetrahydrofuran solution containing terephthaloyl chloride is: adding terephthaloyl chloride into a tetrahydrofuran solution and stirring until dissolved.

4. The high-strength, fast-curing bio-based hot melt adhesive according to claim 1, characterized in that: The preparation method of the β-nucleating agent toughened polypropylene / SiO2 nano-composite is as follows: polypropylene, β-nucleating agent and KH550 modified nano-SiO2 are added to a twin-screw extruder for melt granulation to obtain the composite.

5. The high-strength, fast-curing bio-based hot melt adhesive according to claim 1, characterized in that: The preparation method of the organic borosiloxane polymer is as follows: hydroxy silicone oil is placed in an aluminum beaker, and the beaker is placed on a constant temperature magnetic stirrer, and the temperature is raised to 100-105° C., and pre-treated boric acid is added thereto in small amounts and multiple times. After the addition is completed, the temperature is raised to 120-125° C., and then raised to 150-155° C. with sufficient stirring, and kept warm for 15-25 minutes to obtain the organic borosiloxane polymer.

6. The high-strength, fast-curing bio-based hot melt adhesive according to claim 5, characterized in that: The pretreatment process of boric acid is as follows: grinding the boric acid in a mortar for 30-40 minutes.

7. The high-strength, fast-curing bio-based hot melt adhesive according to claim 1, characterized in that: In step S1, the antioxidant is any one of β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, butylated hydroxyanisole, 2,6-di-tert-butyl-4-methylphenol, 2,2'-methylenebis(4-methyl-6-tert-butyl)phenol, and N,N'-di(2-naphthyl)-p-phenylenediamine, or a mixture of several thereof.

8. The high-strength, fast-curing bio-based hot melt adhesive according to claim 1, characterized in that: In step S1, the catalyst is an organic metal catalyst.

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