Electrically-detachable bio-based reactive polyurethane hot melt adhesive with low free isocyanate content as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of polyurethane hot melt adhesives, and relates to a bio-based reactive polyurethane hot melt adhesive which is low in free isocyanate content and can be electrically disassembled, and a preparation method and application of the bio-based reactive polyurethane hot melt adhesive. The bio-based reactive polyurethane hot melt adhesive is prepared from the following raw materials: a solid electrolyte, a bio-based polyol compound, a low-free polyurethane prepolymer, a silane coupling agent and optional tackifying resin, a catalyst and a water absorbent. The solid electrolyte is oxide-based solid electrolyte and / or sulfide-based solid electrolyte; the mass ratio of the solid electrolyte to the bio-based polyol compound to the silane coupling agent is (25-70): 100: (20-50). The preparation method is characterized in that a specific solid electrolyte is introduced into a polyurethane hot melt adhesive system, and the ratio of the solid electrolyte to the bio-based polyol compound to the silane coupling agent is regulated and controlled; the bio-based reactive polyurethane hot melt adhesive prepared by the method has the advantages of low free isocyanate content, excellent bonding performance and detachability under an electrified condition.

Description

Technical Field

[0001] The invention belongs to the technical field of polyurethane hot melt adhesives, and specifically relates to a bio-based reactive polyurethane hot melt adhesive with low free isocyanate content and electrical decomposability, as well as a preparation method and application thereof. Background Art

[0002] In electronic products such as smartphones, tablets, smart watches, and TWS headphones, reactive polyurethane hot melt adhesives are often used to bond and fix electronic product components. Since electronic product components bonded with reactive polyurethane hot melt adhesives are often of high value, when poor assembly, product after-sales repairs, and recycling of valuable electronic product components occur, it is usually necessary to disassemble some of the bonded components. Therefore, the adhesive used is usually required to have excellent bonding reliability and the function of easy disassembly under certain conditions.

[0003] The main body of reactive polyurethane hot melt adhesive is an oligomer terminated by isocyanate. Isocyanate can react with moisture in the air and form a cross-linked chemical structure after complete curing to achieve high bonding strength. Since the covalent bond obtained by the reaction of isocyanate with moisture is irreversible, the cross-linked structure is difficult to be destroyed. It is usually difficult to disassemble the adhesive after complete curing, and it often requires the help of large external forces, high temperatures, chemical reagents and other conditions. The above methods may cause damage to the bonded materials during the disassembly of the adhesive, causing large economic losses. In recent years, there is a technology that adds alkali metal salts and solvated matrices to polyurethane hot melt adhesives to form liquid electrolytes, giving polyurethane hot melt adhesives the function of being disassembled under power-on conditions. However, although the existing power-on disassembled polyurethane hot melt adhesive has the function of being disassembled under power-on conditions, it still has a large gap with the traditional widely used polyurethane hot melt adhesive in terms of bonding strength, curing speed, heat resistance and other properties. In other words, the power-on disassembled polyurethane hot melt adhesive developed by the prior art is still difficult to meet the performance requirements of actual application scenarios. In addition, the electrically disassembled polyurethane hot melt adhesive prepared by the prior art often contains a large amount of free isocyanate monomers (>1wt%), which will gasify at 85-200°C to form irritating, allergic or toxic substances, endangering the health of practitioners. At the same time, the raw materials used in existing electrically disassembled adhesives are mainly derived from petroleum-based chemical raw materials, which are non-renewable raw materials and are not conducive to achieving sustainable development.

[0004] Therefore, there is an urgent need to develop a bio-based reactive polyurethane hot melt adhesive with low free isocyanate monomer content (≤0.1wt%), which can be disassembled under power conditions and has excellent bonding properties to meet the future market demand for environmentally friendly high-performance detachable polyurethane hot melt adhesives. Summary of the invention

[0005] The first purpose of the present invention is to provide a bio-based reactive polyurethane hot melt adhesive with low free isocyanate monomer content, electrical disassembly and excellent bonding performance, in order to address the shortcomings of existing electrically disassembled adhesives, such as high free isocyanate monomer content, poor bonding performance and the raw materials of which are mainly derived from petroleum-based chemical raw materials. This invention provides a solution to the problem of meeting the future market demand for environmentally friendly high-performance detachable polyurethane hot melt adhesives.

[0006] Specifically, the raw materials for preparing the bio-based reactive polyurethane hot melt adhesive contain a solid electrolyte, a bio-based polyol compound, a low-free polyurethane prepolymer, a silane coupling agent, and optional tackifying resins, catalysts, and water absorbents; the solid electrolyte is an oxide-based solid electrolyte and / or a sulfide-based solid electrolyte; the mass ratio of the solid electrolyte, the bio-based polyol compound, and the silane coupling agent is (25-70):100:(20-50).

[0007] In a preferred embodiment, the content of the solid electrolyte is 5 to 15 parts by weight, the content of the bio-based polyol compound is 15 to 35 parts by weight, the content of the low-free polyurethane prepolymer is 35 to 65 parts by weight, the content of the silane coupling agent is 5 to 10 parts by weight, the content of the tackifying resin is 0 to 15 parts by weight, the content of the catalyst is 0 to 2 parts by weight, and the content of the water absorbent is 0 to 2 parts by weight.

[0008] In a preferred embodiment, the ionic conductivity of the solid electrolyte at room temperature is 10 -4 S / cm or more.

[0009] In a preferred embodiment, the D50 or D90 particle size of the solid electrolyte is 0.3-30 μm.

[0010] In a preferred embodiment, the bio-based polyol compound is completely or partially prepared by reacting bio-based monomer raw materials.

[0011] In a preferred embodiment, the bio-based monomer raw material is selected from succinic acid, adipic acid, dimerized fatty acid, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, C 8 ~C 16 dicarboxylic acid, C 6 ~C 12 At least one of lactide, castor oil and castor oil derived polyol.

[0012] In a preferred embodiment, the free isocyanate monomer content in the low-free polyurethane prepolymer is ≤0.1 wt%.

[0013] In a preferred embodiment, the low-free polyurethane prepolymer includes a low-free polyether polyol-based polyurethane prepolymer and / or a low-free polyester polyol-based polyurethane prepolymer.

[0014] In a preferred embodiment, the low-free polyether polyol-based polyurethane prepolymer is obtained by reacting polyether polyol with polyisocyanate monomer I.

[0015] In a preferred embodiment, the low-free polyester polyol-based polyurethane prepolymer is obtained by reacting polyester polyol with polyisocyanate monomer II.

[0016] In a preferred embodiment, the polyether polyol is at least one selected from the group consisting of ring-opening polymers, random copolymers and block copolymers of ethylene glycol, propylene glycol, tetrahydrofuran and 3-methyltetrahydrofuran.

[0017] In a preferred embodiment, the polyester polyol is at least one selected from polyethylene adipate diol, polypropylene adipate diol, poly1,3-butylene adipate diol, poly1,4-butylene adipate diol, polyneopentyl adipate diol, and poly1,6-hexanediol adipate diol.

[0018] In a preferred embodiment, the polyisocyanate monomer I and the polyisocyanate monomer II are each independently selected from at least one of isophorone diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, hexamethylene diisocyanate, diphenylmethane-4,4'-diisocyanate, diphenylmethane-2,4'-diisocyanate, hydrogenated MDI, polymeric MDI, 1,5-naphthalene diisocyanate, 1,4-phenylene diisocyanate, xylylene diisocyanate, tetramethylxylene diisocyanate and norbornane diisocyanate.

[0019] In a preferred embodiment, the tackifying resin is selected from at least one of thermoplastic polyacrylic resin, polyurethane resin, amorphous poly-alpha-olefin resin, rosin resin, rosin pentaerythritol ester, petroleum resin, terpene resin and EVA resin.

[0020] In a preferred embodiment, the silane coupling agent is selected from at least one of mercaptosilane, epoxysilane, aminosilane, alkenylsilane and isocyanatesilane.

[0021] In a preferred embodiment, the catalyst is at least one selected from dibutyltin dilaurate, stannous octoate, triethylamine, diethylenetriamine, triethylenediamine, N-ethylmorpholine and 2,2-dimorpholinyl diethyl ether.

[0022] In a preferred embodiment, the water absorbent is selected from at least one of a molecular sieve desiccant, an oxazolidine dehydrating agent, p-toluenesulfonyl isocyanate and triethyl orthoformate.

[0023] The second object of the present invention is to provide a method for preparing the above-mentioned bio-based reactive polyurethane hot melt adhesive, which comprises uniformly mixing a solid electrolyte, a bio-based polyol compound, a low-free polyurethane prepolymer, a silane coupling agent, and optional tackifying resins, catalysts, and water absorbents to obtain a bio-based reactive polyurethane hot melt adhesive.

[0024] The third object of the present invention is to provide application of the above-mentioned bio-based reactive polyurethane hot melt adhesive in bonding electronic products.

[0025] After extensive and in-depth research, the inventors of this application have found that the existing electrically disassembled polyurethane hot melt adhesives are usually given the function of being disassembled under power-on conditions by adding alkali metal salts and solvated matrices to form liquid electrolytes. However, since the liquid electrolyte is a liquid substance, it cannot participate in the curing of the polyurethane hot melt adhesive. After the polyurethane hot melt adhesive is cured, the uncured liquid electrolyte will remain in the curing system to form a "plasticizer", which changes the internal structure of the curing system. The presence of this "plasticizer" has a large negative impact on the bonding strength, which will greatly reduce the bonding performance of the polyurethane hot melt adhesive and reduce the bonding reliability of the adhesive system. In addition, due to the poor compatibility between inorganic solid electrolyte materials and organic polyurethane hot melt adhesives, it is usually difficult to evenly disperse them in the polyurethane hot melt adhesive system, which limits its application in electrically disassembled polyurethane hot melt adhesives.

[0026] The key to the present invention is to disregard the limitation of the traditional concept that inorganic solid electrolytes are difficult to be evenly dispersed in the polyurethane hot melt adhesive system and should be used with caution. A specific solid electrolyte (oxide-based solid electrolyte and / or sulfide-based solid electrolyte) is introduced into the polyurethane hot melt adhesive system in the presence of a silane coupling agent, and the ratio between the solid electrolyte, the bio-based polyol compound and the silane coupling agent is regulated. At the same time, a low-free polyurethane prepolymer is introduced to replace the isocyanate monomer in the traditional polyurethane hot melt adhesive. The bio-based reactive polyurethane hot melt adhesive prepared in this way has the advantages of low free isocyanate content, excellent bonding performance, and can be disassembled under power-on conditions, which is expected to meet the future market application demand for environmentally friendly, high-performance, detachable polyurethane hot melt adhesives. The reason is speculated to be that: oxide-based solid electrolytes and sulfide-based solid electrolytes have good compatibility with polyurethane hot melt adhesives under the synergistic effect of silane coupling agents, and can be well dispersed in the polyurethane hot melt adhesive system; in addition, the introduced solid electrolyte itself is solid, and will not form a "plasticizer" after the polyurethane hot melt adhesive is cured, causing its internal structure to change to affect the bonding strength. On the contrary, due to the solid nature of the solid electrolyte itself, it can be used as a filler to reinforce the colloid and improve the bonding performance of the polyurethane hot melt adhesive. At the same time, the oxide-based solid electrolyte and the sulfide-based solid electrolyte themselves have high ionic conductivity in the solid state, and can undergo Faraday electrochemical reactions under power-on conditions, weakening the bonding force at the adhesive bonding interface, thereby giving the polyurethane hot melt adhesive detachable properties. In addition, the present invention uses a polyurethane prepolymer with a low free isocyanate content to replace the traditionally used isocyanate monomer, which can significantly reduce the residual free isocyanate monomer in the adhesive system. DETAILED DESCRIPTION

[0027] The raw materials for preparing the bio-based reactive polyurethane hot melt adhesive provided by the present invention contain a solid electrolyte, a bio-based polyol compound, a low-free polyurethane prepolymer, a silane coupling agent, and optional tackifying resins, catalysts, and water absorbents. The mass ratio of the solid electrolyte to the bio-based polyol compound is (25-70):100, such as 25:100, 30:100, 40:100, 50:100, 60:100, 70:100, or any value therebetween. The mass ratio of the bio-based polyol compound to the silane coupling agent is 100:(20-50), such as 100:20, 100:25, 100:30, 100:35, 100:40, 100:45, 100:50, or any value therebetween. The solid electrolyte is an oxide-based solid electrolyte and / or a sulfide-based solid electrolyte. The structural features of the oxide-based solid electrolyte are preferably selected from at least one of NASICON type, garnet type and perovskite type. The structural features of the sulfide-based solid electrolyte are preferably selected from at least one of amorphous type, crystalline type and glass ceramic type.

[0028] In the present invention, the content of the solid electrolyte is preferably 5 to 15 parts by weight, such as 5, 8, 10, 12, 15 parts by weight or any value therebetween; the content of the bio-based polyol compound is preferably 15 to 35 parts by weight, such as 15, 18, 20, 22, 25, 28, 30, 32, 35 parts by weight or any value therebetween; the content of the low free polyurethane prepolymer is preferably 35 to 65 parts by weight, such as 35, 40, 45, 50, 55, 60, 65 parts by weight or any value therebetween; the content of the silane coupling agent is preferably The content of the tackifying resin is preferably 0-15 parts by weight, such as 0, 5, 8, 10, 12, 15 parts by weight or any value therebetween; the content of the catalyst is preferably 0-2 parts by weight, such as 0, 0.1, 0.5, 0.8, 1, 1.5, 2 parts by weight or any value therebetween; the content of the water absorbent is preferably 0-2 parts by weight, such as 0, 0.1, 0.5, 0.8, 1, 1.5, 2 parts by weight or any value therebetween.

[0029] In the present invention, the solid electrolyte is an oxide-based solid electrolyte and / or a sulfide-based solid electrolyte. The ionic conductivity of the oxide-based solid electrolyte and / or the sulfide-based solid electrolyte at room temperature is generally 10 -4 S / cm or more, and its source and type can be various existing options. The D50 or D90 particle size of the solid electrolyte is preferably 0.3 to 30 μm, such as 0.3 μm, 0.5 μm, 0.8 μm, 1 μm, 5 μm, 10 μm, 20 μm, 30 μm or any value therebetween. When the D50 or D90 particle size of the solid electrolyte is within the above preferred range, it is more conducive to the uniform dispersion of the solid electrolyte in the polyurethane hot melt adhesive system, giving it good electrical disassembly performance, and it is also more conducive to the reinforcing role of the solid electrolyte as a filler, and cooperating with other raw material components to improve the bonding performance of the polyurethane hot melt adhesive system. The term "D50 or D90 particle size" refers to the particle size corresponding to when the cumulative particle size distribution percentage of a sample reaches 50% or 90%.

[0030] In the present invention, the bio-based polyol compound can be completely prepared by reacting a bio-based monomer raw material, or can be prepared by reacting a bio-based monomer raw material and a petroleum-based monomer raw material, and contains at least two hydroxyl groups. Preferably, the bio-based monomer raw material can be exemplarily selected from succinic acid, adipic acid, dimerized fatty acid, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, C 8 ~C 16 dicarboxylic acid, C6 ~C 12 At least one of lactide, castor oil and castor oil derived polyol. 8 ~C 16 The dicarboxylic acid may be an aliphatic or aromatic dicarboxylic acid, and specific examples thereof include, but are not limited to, at least one of suberic acid, azelaic acid, sebacic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, terephthalic acid, (o-)phthalic acid, isophthalic acid, adipic acid, glutaric acid, succinic acid, pimelic acid, and heptane dicarboxylic acid. The C 6 ~C 12 The lactide may be substituted or unsubstituted lactide (lactide is understood to mean a cyclic diester of lactic acid), i.e., the lactide may be substituted by one or more C 1 -C 6 Alkyl substitution. The source of the bio-based monomer raw material can be renewable raw materials such as wheat, straw, corn, soybean, castor oil, etc. As commercially available bio-based polyols, illustratively, at least one of Dynacoll Terra EP481.01, Dynacoll Terra EP480.01, Dynacoll Terra EP480.02, Dynacoll Terra EP424.01, Dynacoll Terra EP424.02, Dynacoll Terra EP413.01, Dynacoll Terra EP413.02, Dynacoll Terra EP413.03, Dynacoll Terra EP413.04 of Evonik, Priplast 3238, Priplast 1838 of Croda, and Velvetol H2000 of Allessa GmbH. The number average molecular weight (Mn) of the bio-based polyol compound is preferably 1500-4000 g / mol, such as 1500 g / mol, 2000 g / mol, 2500 g / mol, 3000 g / mol, 3500 g / mol, 4000 g / mol or any value therebetween.

[0031] In the present invention, the low-free polyurethane prepolymer refers to a polyurethane prepolymer with a low free isocyanate content. The free isocyanate monomer content contained in the low-free polyurethane prepolymer is preferably ≤0.1wt%. The low-free polyurethane prepolymer may include only low-free polyether polyol-based polyurethane prepolymer, or only low-free polyester polyol-based polyurethane prepolymer, or both low-free polyether polyol-based polyurethane prepolymer and low-free polyester polyol-based polyurethane prepolymer. Specifically, the low-free polyether polyol-based polyurethane prepolymer may be commercially available, or may be obtained by reacting a polyether polyol with a polyisocyanate monomer I. Among them, the commercially available low-free polyether polyol-based polyurethane prepolymer can be exemplified as: at least one of Adiprene LF TE 915, Adiprene LF TE1050, Adiprene LF TE 980, Adiprene LF TE 330, Adiprene LF TE 365, Adiprene LF TE440, Adiprene LF 900A, Adiprene LFM G730, Adiprene LFM G750, Adiprene LFM G600, Adiprene LFMI G600, and Adiprene LFMI G1000 of LANXESS. The polyether polyol can be a conventional choice in the art, preferably at least one of a ring-opening polymer, a random copolymer, and a block copolymer of ethylene glycol, propylene glycol, tetrahydrofuran, and 3-methyltetrahydrofuran.

[0032] Specifically, the low-free polyester polyol-based polyurethane prepolymer can be commercially available, or can be obtained by reacting polyester polyol with polyisocyanate monomer II. Among them, the commercially available low-free polyester polyol-based polyurethane prepolymer can be exemplified by at least one of Adiprene LFM S200, Adiprene LFM S300, and Adiprene LFM S500 of Lanxess. The polyester polyol can be a conventional choice in the art, preferably at least one of polyethylene adipate glycol ester diol, polypropylene adipate glycol ester diol, poly1,3-butylene adipate glycol ester diol, poly1,4-butylene adipate glycol ester diol, polyneopentyl adipate glycol ester diol, and poly1,6-hexanediol adipate glycol ester diol. The polyisocyanate monomer I and the polyisocyanate monomer II may be the same or different, and specific examples thereof include, but are not limited to, at least one of isophorone diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, hexamethylene diisocyanate, diphenylmethane-4,4'-diisocyanate, diphenylmethane-2,4'-diisocyanate, hydrogenated MDI, polymeric MDI, 1,5-naphthalene diisocyanate, 1,4-phenylene diisocyanate, xylylene diisocyanate, tetramethylxylene diisocyanate and norbornane diisocyanate.

[0033] The present invention does not specifically limit the type of the tackifying resin, which can be a conventional choice in the art, and specific examples thereof include but are not limited to: at least one of thermoplastic polyacrylic resin, polyurethane resin, amorphous poly-alpha-olefin resin, rosin resin, rosin pentaerythritol ester, petroleum resin, terpene resin and EVA resin.

[0034] In the present invention, the silane coupling agent can be a conventional choice in the art, preferably at least one of mercaptosilane, epoxysilane, aminosilane, alkenylsilane and isocyanate silane, and specific examples thereof include but are not limited to: 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropylmethyldiethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxy At least one of propylmethyldiethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-(2-aminoethyl)aminopropyltrimethoxysilane, 3-(2-aminoethyl)aminopropyltriethoxysilane, 3-(2-aminoethyl)aminopropylmethyldimethoxysilane, 3-(methyl)acryloxypropyltrimethoxysilane, 3-(methyl)acryloxypropyltriethoxysilane, 3-(methyl)acryloxypropylmethyldimethoxysilane, 3-(methyl)acryloxypropylmethyldiethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, and 3-isocyanatepropyltrimethoxysilane. The addition of the silane coupling agent helps to promote the uniform dispersion of the solid electrolyte in the polyurethane hot melt adhesive system, thereby facilitating the electrical disassembly performance of the polyurethane hot melt adhesive system.

[0035] The present invention does not specifically limit the type of the catalyst, which can be a conventional choice in the art, and specific examples include but are not limited to: at least one of dibutyltin dilaurate, stannous octoate, triethylamine, diethylenetriamine, triethylenediamine, N-ethylmorpholine and 2,2-dimorpholinyl diethyl ether.

[0036] The present invention does not impose any specific limitation on the type of the water absorbent, which can be a conventional choice in the art, and specific examples thereof include but are not limited to: at least one of a molecular sieve desiccant, an oxazolidine dehydrating agent, p-toluenesulfonyl isocyanate and triethyl orthoformate.

[0037] The preparation method of the above-mentioned bio-based reactive polyurethane hot melt adhesive provided by the present invention comprises uniformly mixing a solid electrolyte, a bio-based polyol compound, a low-free polyurethane prepolymer, a silane coupling agent, and an optional tackifying resin, a catalyst, and a water absorbent to obtain a bio-based reactive polyurethane hot melt adhesive. The mixing method is not particularly limited. In a preferred embodiment, the above-mentioned mixing specifically comprises the following steps: S1. Mixing a bio-based polyol compound, a solid electrolyte, a silane coupling agent, and an optional tackifying resin and a water absorbent, and then subjecting the mixture to a vacuum dehydration treatment to obtain a pretreated product; S2. Mixing the pretreated product with a low-free polyurethane prepolymer and an optional catalyst to obtain a bio-based reactive polyurethane hot melt adhesive.

[0038] In a specific embodiment, in step S1, the conditions for vacuum dehydration include a temperature of preferably 100-120°C, such as 100°C, 105°C, 110°C, 115°C, 120°C or any value therebetween; a time of preferably 1-5h, such as 1h, 2h, 3h, 4h, 5h or any value therebetween; and a stirring speed of preferably 100-200r / min, such as 100r / min, 120r / min, 150r / min, 180r / min, 200r / min or any value therebetween.

[0039] In a specific embodiment, in step S2, the mixing treatment is preferably carried out by stirring and mixing under vacuum conditions, and the temperature is preferably 70-90°C, such as 70°C, 75°C, 80°C, 85°C, 90°C or any value therebetween; the time is preferably 1-5h, such as 1h, 2h, 3h, 4h, 5h or any value therebetween; the stirring speed is preferably 100-200r / min, such as 100r / min, 120r / min, 150r / min, 180r / min, 200r / min or any value therebetween.

[0040] The bio-based reactive polyurethane hot melt adhesive provided by the present invention can be applied to an adhesive substrate that can be electrified, and the voltage for electrification and disassembly can be 1 to 100V, such as 1V, 3V, 5V, 7V, 10V, 20V, 50V, 60V, 80V, 100V or any value therebetween, and the time for electrification and disassembly can be 1s to 60min, such as 1s, 2s, 10s, 30s, 50s, 1min, 2min, 5min, 10min, 20min, 30min, 40min, 50min, 60min or any value therebetween. In addition, the adhesive substrate used by the bio-based reactive polyurethane hot melt adhesive is a conductive substrate.

[0041] The present invention will be described in detail below through specific embodiments.

[0042] The parts involved in the following examples and comparative examples are all parts by weight.

[0043] The raw materials and sources in the following examples and comparative examples are as follows:

[0044] Bio-based polyester diol, purchased from Stepan Company, brand name Stepanpol PDP70; bio-based polyester diol, purchased from Oleon Company of Belgium, brand name RADIA 7287; polybutylene adipate diol, purchased from Qingdao Xinyutian Chemical Company, brand name POL-338; polytetramethylene ether diol, purchased from PTG Company of South Korea, brand name PTMEG-2000.

[0045] Acrylic resin, purchased from Mitsubishi Chemical Corporation, brand BR106; polyurethane resin, purchased from Lubrizol Corporation, brand Pearlbond 523; polyurethane resin, purchased from Lubrizol Corporation, brand Pearlbond 539; acrylic resin, purchased from Shanghai Bolier Chemical Company, brand BM751; polyalphaolefin resin, purchased from Evonik Specialty Chemicals, brand VESTOPLAST 520; triethyl orthoformate water absorbent, purchased from Borchers, Germany, brand Additive OF.

[0046] NASICON oxide-based solid electrolyte LATP, D50 = 0.6 μm, purchased from Zhejiang Fengli New Energy Technology Co., Ltd., brand LATP-600, ionic conductivity at room temperature ≥ 6*10 -4 S / cm; sulfide-based solid electrolyte FL-LPSC, D90 = 20 μm, purchased from Zhejiang Fengli New Energy Technology Co., Ltd., brand LPSC-20000, ionic conductivity at room temperature is 6*10 - 3 S / cm; garnet oxide-based solid electrolyte FL-GTEP, D50 = 0.5 μm, purchased from Zhejiang Fengli New Energy Technology Co., Ltd., brand GTEP-500, ionic conductivity at room temperature ≥ 8*10 -4 S / cm; sulfide-based solid electrolyte FL-LPSC, D50 = 30 μm, purchased from Zhejiang Fengli New Energy Technology Co., Ltd., brand LPSC-30000, ionic conductivity at room temperature is 1*10 - 2 S / cm; NASICON oxide-based solid electrolyte LATP, D50 = 0.3 μm, purchased from Zhejiang Fengli New Energy Technology Co., Ltd., brand LATP-300, ionic conductivity at room temperature ≥ 6*10 -4 S / cm; NASICON oxide-based solid electrolyte LATP, D50 = 0.1 μm, purchased from Bluegoo New Energy Technology Co., Ltd., brand LG1117, ionic conductivity at room temperature is 5*10- 4 S / cm~1*10 -3 S / cm; sulfide-based solid electrolyte LGPS, D50 = 50 μm, purchased from Shenzhen ASML New Energy Co., Ltd., brand LGPS-50 μm, ionic conductivity at room temperature is ≥7*10 -3 S / cm; Polyethylene oxide PEO solid electrolyte, purchased from Cluder, brand E-30, ionic conductivity at room temperature is 6.29*10 -6 S / cm.

[0047] The p-toluenesulfonyl isocyanate water absorbent was purchased from Borchers, Germany, with the brand name Additive TI; the triethyl orthoformate water absorbent was purchased from Borchers, Germany, with the brand name Additive OF; the adsorbent molecular sieve water absorbent was purchased from ARkEMA, with the brand name Siliporite SA1702.

[0048] Example 1

[0049] 19.78 parts of bio-based polyester diol Dynacoll Terra 424.01 (Mn = 3500 g / mol), 11.30 parts of bio-based polyether diol Velvetol H2000 (Mn = 2000 g / mol), 10.00 parts of acrylic resin BR106, 10.00 parts of NASICON type oxide-based solid electrolyte LATP (D50 = 0.6 μm), 7.00 parts of vinyl trimethoxy silane, and 0.10 parts of water absorbent Additive OF were added to a reaction bottle, heated to 110°C, and vacuum dehydrated for 2 hours under stirring conditions of 150 r / min; then cooled to 80°C, 31.12 parts of low-free polyether polyol-based polyurethane prepolymer Adiprene LF TE 915 and 10.00 parts of low-free polyester polyol-based polyurethane prepolymer Adiprene LFM were added. S300 and 0.30 parts of dibutyltin dilaurate were reacted under stirring conditions of 150 r / min for 2 hours, and then the material was discharged to obtain a bio-based reactive polyurethane hot melt adhesive, which was vacuum sealed and stored.

[0050] Example 2

[0051] 8.84 parts of bio-based polyester diol Priplast 3238 (Mn = 2000 g / mol), 8.84 parts of bio-based polyester diol Stepanpol PDP70 (Mn = 1600 g / mol), 7.00 parts of polyurethane resin Pearlbond 523, 6.00 parts of sulfide-based solid electrolyte FL-LPSC (D90 = 20 μm), 5.00 parts of vinyl trimethoxysilane, and 0.10 parts of water absorbent Additive OF were added to a reaction bottle, heated to 110°C, and vacuum dehydrated for 2 hours under stirring conditions of 150 r / min; then cooled to 80°C, 54.13 parts of low-free polyether polyol-based polyurethane prepolymer Adiprene LF 900A and 10.00 parts of low-free polyester polyol-based polyurethane prepolymer Adiprene LFM were added. S200 and 0.10 parts of stannous octoate were reacted under stirring conditions of 150 r / min for 2 hours, and then the material was discharged to obtain a bio-based reactive polyurethane hot melt adhesive, which was vacuum sealed and stored.

[0052] Example 3

[0053] 15.71 parts of bio-based polyester diol Dynacoll Terra 481.01 (Mn = 3500 g / mol), 8.98 parts of bio-based polyester diol RADIA 7287 (Mn = 2000 g / mol), 12.00 parts of polyurethane resin Pearlbond539, 15.00 parts of garnet-type oxide-based solid electrolyte FL-GTEP (D50 = 0.5 μm), 10.00 parts of 3-glycidoxypropyltrimethoxysilane, and 1.00 parts of water absorbent Additive TI were added to a reaction bottle, heated to 110°C, and vacuum dehydrated for 2 hours under stirring conditions of 150 r / min; then cooled to 80°C, 30.81 parts of low-free polyether polyol-based polyurethane prepolymer Adiprene TE980 and 5.00 parts of low-free polyester polyol-based polyurethane prepolymer Adiprene LFM were added. S500 and 1.50 parts of 2,2-dimorpholinyl diethyl ether were reacted for 2 hours under stirring at 150 r / min to obtain a bio-based reactive polyurethane hot melt adhesive, which was sealed in a vacuum for storage.

[0054] Example 4

[0055] 15.66 parts of bio-based polyester diol Stepanpol PDP70 (Mn = 1600 g / mol), 6.52 parts of bio-based polyether diol Velvetol H2000 (Mn = 2000 g / mol), 8.00 parts of acrylic resin BM751, 8.50 parts of sulfide-based solid electrolyte FL-LPSC (D50 = 30 μm), 6.60 parts of 3-mercaptopropyltrimethoxysilane, and 1.50 parts of water absorbent SiliporiteSA1702 were added to a reaction bottle, heated to 110°C, and vacuum dehydrated for 2 hours under stirring conditions of 150 r / min; then cooled to 80°C, 45.02 parts of low-free polyether polyol-based polyurethane prepolymer Adiprene G730 and 8.00 parts of low-free polyester polyol-based polyurethane prepolymer Adiprene LFM S200 and 0.70 parts of stannous octoate were reacted under stirring conditions of 150 r / min for 2 hours, and then the material was discharged to obtain a bio-based reactive polyurethane hot melt adhesive, which was vacuum sealed and stored.

[0056] Example 5

[0057] 10.22 parts of bio-based polyester diol Dynacoll Terra 481.01 (Mn = 3500 g / mol), 10.22 parts of bio-based polyester diol Dynacoll Terra 424.01 (Mn = 3500 g / mol), 6.50 parts of polyalphaolefin resin VESTOPLAST520, 12.50 parts of NASICON type oxide-based solid electrolyte LATP (D50 = 0.3 μm), 9.00 parts of 3-glycidoxypropyltrimethoxysilane, and 2.00 parts of water absorbent Additive TI were added to a reaction bottle, heated to 110°C, and vacuum dehydrated for 2 hours under stirring conditions of 150 r / min; then cooled to 80°C, 39.05 parts of low-free polyether polyol-based polyurethane prepolymer Adiprene TE 440 and 8.50 parts of low-free polyester polyol-based polyurethane prepolymer Adiprene LFM were added. S300 and 2.00 parts of 2,2-dimorpholinyl diethyl ether were reacted for 2 hours under stirring at 150 r / min to obtain a bio-based reactive polyurethane hot melt adhesive, which was sealed in a vacuum for storage.

[0058] Example 6

[0059] A bio-based reactive polyurethane hot melt adhesive was prepared according to the method of Example 1, except that the same amount of NASICON-type oxide-based solid electrolyte LATP with D50=0.1μm was used instead of NASICON-type oxide-based solid electrolyte LATP with D50=0.6μm, and the other conditions were the same as in Example 1, thereby preparing a bio-based reactive polyurethane hot melt adhesive.

[0060] Example 7

[0061] A bio-based reactive polyurethane hot melt adhesive was prepared according to the method of Example 1, except that the same amount of sulfide-based solid electrolyte LGPS-50μm with D50=50μm was used instead of NASICON-type oxide-based solid electrolyte LATP with D50=0.6μm, and the other conditions were the same as in Example 1, thereby preparing a bio-based reactive polyurethane hot melt adhesive.

[0062] Comparative Example 1

[0063] A reference bio-based reactive polyurethane hot melt adhesive was prepared according to the method of Example 1, except that NASICON-type oxide-based solid electrolyte LATP (D50=0.6 μm) was not added, and the other conditions were the same as those in Example 1, thereby preparing a reference bio-based reactive polyurethane hot melt adhesive.

[0064] Comparative Example 2

[0065] A reference bio-based reactive polyurethane hot melt adhesive was prepared according to the method of Example 1, except that the addition amount of NASICON-type oxide-based solid electrolyte LATP (D50=0.6 μm) was reduced to 1.00 parts, and the other conditions were the same as those in Example 1, thereby preparing a reference bio-based reactive polyurethane hot melt adhesive.

[0066] Comparative Example 3

[0067] A reference bio-based reactive polyurethane hot melt adhesive was prepared according to the method of Example 1, except that the amount of vinyltrimethoxysilane added was reduced to 1.00 parts, and the other conditions were the same as those of Example 1, thereby preparing a reference bio-based reactive polyurethane hot melt adhesive.

[0068] Comparative Example 4

[0069] 35.65 parts of polybutylene adipate diol POL-338 (Mn=3000 g / mol), 20.37 parts of polytetramethylene ether diol PTMEG-2000 (Mn=2000 g / mol), 12.00 parts of acrylic resin BR-106, 5.00 parts of lithium trifluoromethanesulfonate, 15.00 parts of propylene carbonate, and 0.50 parts of water absorbent Additive TI were added to a reaction bottle, heated to 110°C, and vacuum dehydrated for 2 hours under stirring conditions of 150 r / min; then cooled to 80°C, 10.18 parts of 4,4'-diphenylmethane diisocyanate (MDI) and 1.00 parts of stannous octoate were added, and the reaction was carried out under stirring conditions of 150 r / min for 2 hours before discharging to obtain a reference polyurethane hot melt adhesive containing liquid electrolyte, which was vacuum sealed and stored.

[0070] Comparative Example 5

[0071] A reference bio-based reactive polyurethane hot melt adhesive was prepared according to the method of Example 1, except that a polyoxyethylene PEO solid electrolyte (Cruder Company, brand E-30, with an ionic conductivity of 6.29*10 -6 S / cm) instead of NASICON-type oxide-based solid electrolyte LATP (D50=0.6 μm), and the other conditions were the same as those in Example 1, thereby preparing a reference bio-based reactive polyurethane hot melt adhesive.

[0072] Test Case

[0073] The polyurethane hot melt adhesives prepared in the above examples and comparative examples were tested for bonding performance, heat resistance, high temperature and high humidity resistance, and free isocyanate content before and after power on according to the following methods. The results are shown in Table 1.

[0074] (1) Bonding strength test before power on: Use a glue dispenser to dispense the hot melt adhesive obtained in the embodiment and the comparative example at 110° C., and apply a rectangular glue line of 25 mm*4 mm on the stainless steel substrate; then, bond another stainless steel substrate to the stainless steel substrate. After bonding, cure the sample in an environment of 25° C. and 50% RH for 1 day, and then use a universal material testing machine to run the prepared bonding sample along the shear direction at a speed of 10 mm / min until the sample fails to bond. Record the maximum force value displayed by the instrument, and calculate the shear bonding strength of the adhesive to the stainless steel substrate after curing for 1 day based on the bonding area.

[0075] (2) Bonding strength after power-on: After the glue is dispensed and cured according to the method in (1), the sample to be tested is obtained. The positive and negative wires of the DC power supply are clamped at the two ends of the sample respectively. The power is turned on for 30 min or 20 min at a voltage of 48 V or 60 V. After the power-on is completed, the sample is removed and the prepared bonding sample is run along the shear direction at a speed of 10 mm / min using a universal material testing machine until the sample fails to bond. The maximum force value displayed by the instrument is recorded, and the shear bonding strength of the adhesive to the stainless steel substrate after power-on is calculated based on the bonding area (when the bonding strength is less than 2 MPa, it is removable).

[0076] (3) Heat resistance (80°C): The samples to be tested were obtained after curing by the method in (1). The bonded samples were placed in an oven at 80°C for 20 min. The prepared bonded samples were then run in an 80°C environment at a speed of 10 mm / min along the shear direction using a universal material testing machine until the sample failed to bond. The maximum force value displayed by the instrument was recorded, and the shear bonding strength of the adhesive to the stainless steel substrate in a high temperature environment of 80°C was calculated based on the bonding area.

[0077] (4) High temperature and high humidity resistance (85°C, 85% RH): The test specimens were obtained after curing by the method in (1). The bonded shear specimens were placed in a high temperature and high humidity oven at 85°C and 85% RH for 7 days. The prepared bonding specimens were then run along the shear direction at a speed of 10 mm / min using a universal material testing machine until the specimen failed to bond. The maximum force value displayed by the instrument was recorded, and the shear bonding strength of the adhesive to the stainless steel substrate after high temperature and high humidity aging was calculated based on the bonding area.

[0078] (5) Free isocyanate content test: Use a high performance liquid chromatograph (HPLC) with liquid as the mobile phase and a high pressure infusion system to pump the mobile phase into a chromatographic column containing a stationary phase. After the components are separated in the column, they enter the detector for detection to obtain a chromatogram of the test substance. Use the external standard method to quantitatively calculate the content of free isocyanate monomers in the polyurethane hot melt adhesive. Record the chromatograms of the sample to be tested and the standard separately. Calculate the content of free isocyanate in the sample to be tested based on the integrated area of ​​the specific peak on the chromatogram.

[0079] Table 1

[0080]

[0081] It can be seen from the results of Examples 1 to 7 that the free isocyanate content of the bio-based polyurethane hot melt adhesive provided by the present invention is all below 0.1wt%, which is significantly lower than the free isocyanate monomer content of the traditional polyurethane hot melt adhesive (Comparative Example 4), significantly reducing the safety hazards of using polyurethane hot melt adhesive; at the same time, the bio-based polyurethane hot melt adhesive with low free isocyanate content provided by the present invention has excellent bonding strength and good heat resistance and high temperature and high humidity resistance before power-on, and can effectively achieve a significant reduction in bonding strength (down to below 2MPa) after power-on, and has detachability. From the results of Example 1 and Comparative Examples 1, 2, and 5, it can be seen that without adding oxide-based or sulfide-based solid electrolytes, or adding too little solid electrolytes, or adding polymer-based solid electrolytes, the bonding strength of the polyurethane hot melt adhesive is reduced and the bonding strength decreases in a small proportion after power-on, the bonding strength is greater than 2MPa, and it is not detachable, and the heat resistance and high humidity and high temperature resistance are also worse than those of Example 1. It can be seen from the results of Example 1 and Comparative Example 3 that when the amount of silane coupling agent added is too small, the bonding strength, heat resistance and high humidity and high temperature resistance of the polyurethane hot melt adhesive are poor, and the bonding strength decreases slightly after power is turned on (the bonding strength is greater than 2MPa), and it is not removable.

[0082] In summary, the solid electrolyte provided by the present invention for preparing the polyurethane hot melt adhesive has the advantages of bio-based origin, low free isocyanate content, excellent bonding performance, and can be disassembled by power. It is a product with excellent comprehensive performance and is expected to meet the future market application demand for environmentally friendly high-performance detachable polyurethane hot melt adhesives, and has broad application prospects.

[0083] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and intent of the present invention.

Claims

1. A bio-based reactive polyurethane hot melt adhesive, characterized in that: The raw materials for preparing the bio-based reactive polyurethane hot melt adhesive contain a solid electrolyte, a bio-based polyol compound, a low-free polyurethane prepolymer, a silane coupling agent, and optional tackifying resins, catalysts, and water absorbents; the solid electrolyte is an oxide-based solid electrolyte and / or a sulfide-based solid electrolyte; the mass ratio of the solid electrolyte, the bio-based polyol compound, and the silane coupling agent is (25-70):100:(20-50).

2. The bio-based reactive polyurethane hot melt adhesive according to claim 1, characterized in that: The content of the solid electrolyte is 5 to 15 parts by weight, the content of the bio-based polyol compound is 15 to 35 parts by weight, the content of the low-free polyurethane prepolymer is 35 to 65 parts by weight, the content of the silane coupling agent is 5 to 10 parts by weight, the content of the tackifying resin is 0 to 15 parts by weight, the content of the catalyst is 0 to 2 parts by weight, and the content of the water absorbent is 0 to 2 parts by weight; Preferably, the ionic conductivity of the solid electrolyte at room temperature is 10 -4 S / cm or more; Preferably, the D50 or D90 particle size of the solid electrolyte is 0.3-30 μm.

3. The bio-based reactive polyurethane hot melt adhesive according to claim 1, characterized in that: The bio-based polyol compound is prepared completely or partially by reacting bio-based monomer raw materials; Preferably, the bio-based monomer raw material is selected from succinic acid, adipic acid, dimer fatty acid, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, C8-C 16 Dicarboxylic acids, C6~C 12 At least one of lactide, castor oil and castor oil derived polyol.

4. The bio-based reactive polyurethane hot melt adhesive according to claim 1, characterized in that: The free isocyanate monomer content in the low-free polyurethane prepolymer is ≤0.1wt%; preferably, the low-free polyurethane prepolymer includes a low-free polyether polyol-based polyurethane prepolymer and / or a low-free polyester polyol-based polyurethane prepolymer.

5. The bio-based reactive polyurethane hot melt adhesive according to claim 4, characterized in that: The low-free polyether polyol-based polyurethane prepolymer is obtained by reacting polyether polyol with polyisocyanate monomer I; preferably, the low-free polyester polyol-based polyurethane prepolymer is obtained by reacting polyester polyol with polyisocyanate monomer II.

6. The bio-based reactive polyurethane hot melt adhesive according to claim 5, characterized in that: The polyether polyol is selected from at least one of a ring-opening polymer, a random copolymer and a block copolymer of ethylene glycol, propylene glycol, tetrahydrofuran and 3-methyltetrahydrofuran; Preferably, the polyester polyol is selected from at least one of polyethylene adipate diol, polypropylene adipate diol, poly1,3-butylene adipate diol, poly1,4-butylene adipate diol, polyneopentyl adipate diol, and poly1,6-hexanediol adipate diol; Preferably, the polyisocyanate monomer I and the polyisocyanate monomer II are each independently selected from at least one of isophorone diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, hexamethylene diisocyanate, diphenylmethane-4,4'-diisocyanate, diphenylmethane-2,4'-diisocyanate, hydrogenated MDI, polymeric MDI, 1,5-naphthalene diisocyanate, 1,4-phenylene diisocyanate, xylylene diisocyanate, tetramethylxylene diisocyanate and norbornane diisocyanate.

7. The bio-based reactive polyurethane hot melt adhesive according to claim 1, characterized in that: The tackifying resin is selected from at least one of thermoplastic polyacrylic resin, polyurethane resin, amorphous poly-alpha-olefin resin, rosin resin, rosin pentaerythritol ester, petroleum resin, terpene resin and EVA resin; Preferably, the silane coupling agent is selected from at least one of mercaptosilane, epoxysilane, aminosilane, alkenylsilane and isocyanatesilane.

8. The bio-based reactive polyurethane hot melt adhesive according to claim 1, characterized in that: The catalyst is selected from at least one of dibutyltin dilaurate, stannous octoate, triethylamine, diethylenetriamine, triethylenediamine, N-ethylmorpholine and 2,2-dimorpholinyl diethyl ether; Preferably, the water absorbent is selected from at least one of a molecular sieve desiccant, an oxazolidine dehydrating agent, p-toluenesulfonyl isocyanate and triethyl orthoformate.

9. The method for preparing the bio-based reactive polyurethane hot melt adhesive according to any one of claims 1 to 8, characterized in that: The preparation method comprises the steps of uniformly mixing a solid electrolyte, a bio-based polyol compound, a low-free polyurethane prepolymer, a silane coupling agent, and optional tackifying resins, catalysts, and water absorbents to obtain a bio-based reactive polyurethane hot melt adhesive.

10. Use of the bio-based reactive polyurethane hot melt adhesive according to any one of claims 1 to 8 in bonding electronic products.

Images