Electrically removable polyurethane hot melt adhesive having excellent bonding performance, preparation method therefor, and use thereof

Abstract

The present invention relates to the technical field of polyurethane hot melt adhesives, and in particular to an electrically removable polyurethane hot melt adhesive having excellent bonding performance, a preparation method therefor, and a use thereof. Raw materials for preparing the polyurethane hot melt adhesive include a solid electrolyte, a polyol compound, a polyisocyanate compound, a silane coupling agent, and optionally a tackifying resin, a catalyst, and a water absorbent. The mass ratio of the solid electrolyte to the polyol compound to the silane coupling agent is (5-35):100:(5-25). The key of the present invention lies in introducing a specific solid electrolyte (an oxide-based solid electrolyte and / or a sulfide-based solid electrolyte) into a polyurethane hot melt adhesive system and regulating the ratio of the solid electrolyte to the polyol compound to the silane coupling agent. Therefore, the obtained polyurethane hot melt adhesive is not only electrically removable, but also has high bonding strength, good heat resistance, and good high-temperature and high-humidity resistance.

Description

A polyurethane hot melt adhesive with excellent bonding properties and electrical disassembly, its preparation method and application.

[0001] Cross-references to related applications

[0002] This application claims priority to Chinese Patent Application No. 2024114596288, filed on October 18, 2024, entitled "A polyurethane hot melt adhesive with excellent adhesive properties and electrically disintegratable thereof, and its preparation method and application", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This invention belongs to the field of polyurethane hot melt adhesive technology, specifically relating to a polyurethane hot melt adhesive with excellent bonding performance and electrical disassembly, its preparation method, and its application. Background Technology

[0004] In electronic product bonding applications, polyurethane hot melt adhesives are widely used in smartphones, tablets, smartwatches, TWS earphones, and other electronic products due to their high bonding strength after curing. However, in the actual production process of electronic products, there are often situations where it is necessary to disassemble the bonded components for reassembly, repair, or recycling. The main resin of polyurethane hot melt adhesives is an oligomer terminated with isocyanate groups. These isocyanate groups can react with moisture in the air to cure and form a cross-linked chemical structure, thus achieving high bonding strength. The covalent bonds formed by the reaction of isocyanate groups with moisture are irreversible, and the cross-linked structure is difficult to break. Once fully cured, disassembly is usually difficult, often requiring significant external force, high temperatures, or chemical reagents to achieve the purpose of disassembly. This process can easily damage the adhesive substrate. Since electronic product components often have high value, there is a need to find a gentler method for disassembly. In recent years, technologies have emerged that add alkali metal salts and solvation matrices to polyurethane hot melt adhesives to form liquid electrolytes, giving the adhesives the ability to be disassembled under electrical conditions. This allows for gentle disassembly without damaging the electronic bonding substrate. However, while existing electrically disassembleable polyurethane hot melt adhesives possess this disassembly capability, they still lag significantly behind traditionally widely used polyurethane hot melt adhesives in terms of bond strength, curing speed, heat resistance, and resistance to high temperatures and humidity. This limitation restricts the widespread adoption of such electrically disassembleable polyurethane hot melt adhesives. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing electrically disassembleable polyurethane hot melt adhesives, such as poor bonding strength, poor heat resistance, and poor resistance to high temperature and humidity. The invention provides an electrically disassembleable polyurethane hot melt adhesive with high bonding strength, good heat resistance, and good resistance to high temperature and humidity, as well as its preparation method and application.

[0006] In a first aspect, the present invention provides a polyurethane hot melt adhesive, wherein the raw materials for preparing the polyurethane hot melt adhesive contain a solid electrolyte, a polyol compound, a polyisocyanate compound, a silane coupling agent, and optionally a tackifying resin, a catalyst, and a water-absorbing agent; the solid electrolyte is an oxide-based solid electrolyte and / or a sulfide-based solid electrolyte; the mass ratio of the solid electrolyte, the polyol compound, and the silane coupling agent is (5-35):100:(5-25).

[0007] In some specific embodiments, the content of the solid electrolyte is 5-15 parts by weight, the content of the polyol compound is 45-65 parts by weight, the content of the polyisocyanate compound is 10-20 parts by weight, the content of the silane coupling agent is 5-10 parts by weight, the content of the tackifying resin is 0-15 parts by weight, the content of the catalyst is 0-2 parts by weight, and the content of the water absorbent is 0-2 parts by weight.

[0008] In some specific embodiments, the solid electrolyte has an ionic conductivity of 10 at room temperature. -4 S / cm or higher.

[0009] In some specific embodiments, the D50 or D90 particle size of the solid electrolyte is 0.3 to 30 μm.

[0010] In some specific embodiments, the number-average molecular weight of the polyol compound is 1000–4000 g / mol.

[0011] In some specific embodiments, the polyol compound is selected from at least one of polyester polyols, polyether polyols, polycarbonate polyols, and polyalkylene polyols.

[0012] In some specific embodiments, the polyisocyanate compound is selected from at least one of isophorone diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, diphenylmethane-4,4'-diisocyanate, diphenylmethane-2,4'-diisocyanate, hydrogenated phenylenedimethylene diisocyanate, 1,5-naphthalene diisocyanate, 1,5-pentane diisocyanate, 1,4-phenylenedimethylene diisocyanate, m-phenylenedimethyl isocyanate, tetramethylphenylenedimethylene diisocyanate, norbornene diisocyanate, lysine diisocyanate, triphenylmethane triisocyanate, triphenyl thiophosphate triphenyl isocyanate, and 1,6,11-undecane triisocyanate.

[0013] In some specific embodiments, the tackifying resin is selected from at least one of thermoplastic acrylic resin, polyurethane resin, rosin resin, petroleum resin, terpene resin, EVA resin, and amorphous polyolefin resin.

[0014] In some specific embodiments, the silane coupling agent is selected from 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropylmethyldiethoxysilane, 3-epoxypropoxypropyltrimethoxysilane, 3-epoxypropoxypropyltriethoxysilane, 3-epoxypropoxypropylmethyldimethoxysilane, 3-epoxypropoxypropylmethyldiethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-epoxypropoxypropylmethyldiethoxysilane, 3-aminopropyltrimethoxysilane, 3- At least one of aminopropyltriethoxysilane, 3-(2-aminoethyl)aminopropyltrimethoxysilane, 3-(2-aminoethyl)aminopropyltriethoxysilane, 3-(2-aminoethyl)aminopropylmethyldimethoxysilane, 3-(meth)acryloyloxypropyltrimethoxysilane, 3-(meth)acryloyloxypropyltriethoxysilane, 3-(meth)acryloyloxypropylmethyldimethoxysilane, 3-(meth)acryloyloxypropylmethyldiethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, and 3-isocyanate propyltrimethoxysilane.

[0015] In some specific embodiments, the catalyst is selected from at least one of dibutyltin dilaurate, stannous octoate, triethylamine, diethylenetriamine, triethylenediamine, N-ethylmorpholine, and 2,2-dimorpholinodiethyl ether.

[0016] In some specific embodiments, the desiccant is selected from at least one of molecular sieve desiccant, oxazolidine desiccant, p-toluenesulfonyl isocyanate, and triethyl orthoformate.

[0017] Secondly, the present invention provides a method for preparing the above-mentioned polyurethane hot melt adhesive, the method comprising mixing a solid electrolyte, a polyol compound, a polyisocyanate compound, a silane coupling agent, and optionally a tackifying resin, a catalyst, and a water absorbent uniformly to obtain a polyurethane hot melt adhesive.

[0018] Thirdly, the present invention also provides the application of the above-mentioned polyurethane hot melt adhesive in the bonding of electronic products.

[0019] Existing polyurethane hot melt adhesives typically achieve their removable properties by adding liquid electrolytes. However, while liquid electrolytes impart electrical removability to polyurethane hot melt adhesives, they also severely impact their adhesive strength. After in-depth research, the inventors of this invention discovered that one of the main reasons for the significant decrease in adhesive strength is that liquid electrolytes, being liquid substances, are difficult to cure. After the polyurethane hot melt adhesive has cured, the uncured liquid electrolyte remains in the cured system, forming a "plasticizer." This alters the internal structure of the cured system, and the presence of this "plasticizer" has a significant negative impact on adhesive strength, drastically reducing the adhesive performance of the polyurethane hot melt adhesive. Furthermore, due to the poor compatibility between inorganic solid electrolyte materials and organic polyurethane hot melt adhesives, they are usually difficult to disperse uniformly in the polyurethane hot melt adhesive system, limiting their application in electrically removable polyurethane hot melt adhesives.

[0020] The key to this invention lies in overcoming the limitations of the traditional concept that inorganic solid electrolytes are difficult to disperse uniformly in polyurethane hot melt adhesive systems and should be used with caution. Specific solid electrolytes (oxide-based and / or sulfide-based solid electrolytes) are introduced into the polyurethane hot melt adhesive system in the presence of a silane coupling agent. The ratio between the solid electrolyte, polyol compound, and silane coupling agent is controlled. The resulting polyurethane hot melt adhesive not only has electrolytic disintegration properties but also boasts advantages such as high bonding strength, heat resistance, and good resistance to high temperature and humidity. The reasons for this are speculated to be as follows: Oxide-based and sulfide-based solid electrolytes have high ionic conductivity in the solid state, which can undergo Faraday electrochemical reactions under energized conditions, weakening the adhesive force at the bonding interface and thus giving the polyurethane hot melt adhesive removable properties. Furthermore, these two specific solid electrolytes, under the synergistic effect of silane coupling agents, have good compatibility with polyurethane hot melt adhesives and can be well dispersed in the polyurethane hot melt adhesive system. At the same time, oxide-based and sulfide-based solid electrolytes do not cause the polyurethane hot melt adhesive to form "plasticizers" after curing, thus altering its internal structure and affecting the bonding strength. On the contrary, oxide-based and sulfide-based solid electrolytes can also act as fillers to reinforce the colloid, thereby improving the bonding performance of the polyurethane hot melt adhesive and increasing its bonding strength, heat resistance, and resistance to high temperature and humidity. In summary, the polyurethane hot melt adhesive provided by this invention, which has high bonding strength, good heat resistance, high temperature and humidity resistance, and is electrically disassembleable, offers a solution, product, and method for application scenarios in actual production processes that require high bonding reliability and disassembly. Detailed Implementation

[0021] The polyurethane hot melt adhesive provided by this invention contains a solid electrolyte, a polyol compound, a polyisocyanate compound, a silane coupling agent, and optionally a tackifying resin, a catalyst, and a water-absorbing agent. The mass ratio of the solid electrolyte to the polyol compound is (5-35):100, such as 5:100, 10:100, 15:100, 20:100, 25:100, 30:100, 35:100, or any value between them. The mass ratio of the polyol compound to the silane coupling agent is 100:(5-25), such as 100:5, 100:10, 100:15, 100:20, 100:25, or any value between them. The solid electrolyte is an oxide-based solid electrolyte and / or a sulfide-based solid electrolyte. Preferably, the oxide-based solid electrolyte has a structural characteristic selected from at least one of the NASICON type, garnet type, and perovskite type. The structural characteristics of the sulfide-based solid electrolyte are preferably selected from at least one of amorphous, crystalline, and glass-ceramic types.

[0022] In this invention, the amount 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 between them; the amount of the polyol compound is preferably 45 to 65 parts by weight, such as 45, 48, 50, 52, 55, 58, 60, 62, 65 parts by weight or any value between them; the amount of the polyisocyanate compound is preferably 10 to 20 parts by weight, such as 10, 12, 15, 18, 20 parts by weight or any value between them; and the amount of the silane coupling agent is preferably 5 to 10 parts by weight. The dosage of the tackifying resin is preferably 0 to 15 parts by weight, such as 0, 5, 8, 10, 12, 15 parts by weight, or any value between them; the dosage of the catalyst is preferably 0 to 2 parts by weight, such as 0, 0.1, 0.2, 0.5, 0.8, 1, 1.5, 2 parts by weight, or any value between them; the dosage of the water absorbent is preferably 0 to 2 parts by weight, such as 0, 0.1, 0.2, 0.5, 0.8, 1, 1.5, 2 parts by weight, or any value between them.

[0023] In this invention, the solid electrolyte is an oxide-based solid electrolyte and / or a sulfide-based solid electrolyte. The oxide-based and / or sulfide-based solid electrolyte typically has an ionic conductivity of 10 at room temperature. -4The particle size (S / cm) of the solid electrolyte can be of various existing types. The D50 or D90 particle size of the solid electrolyte is preferably 0.3–30 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 between them. When the D50 or D90 particle size of the solid electrolyte is within the above-mentioned preferred range, it is more conducive to the uniform dispersion of the solid electrolyte in the polyurethane hot melt adhesive system, giving it good electrolytic disintegration properties. It is also more conducive to the solid electrolyte acting as a filler to reinforce the polyurethane hot melt adhesive system, and to its interaction with other raw material components to improve the adhesive strength, heat resistance, and high-temperature and high-humidity resistance of the polyurethane hot melt adhesive system. The term "D50 or D90 particle size" refers to the particle size corresponding to a cumulative particle size distribution percentage of 50% or 90% for a sample.

[0024] In this invention, the number-average molecular weight (Mn) of the polyol compound is preferably 1000–4000 g / mol, such as 1000 g / mol, 1500 g / mol, 2000 g / mol, 2500 g / mol, 3000 g / mol, 3500 g / mol, 4000 g / mol, or any value between them. The type and source of the polyol compound can be any of the existing options, preferably from at least one of polyester polyols, polyether polyols, polycarbonate polyols, and polyalkylene polyols. Specifically, the polyester polyol can be a polyester polyol obtained by reacting a polycarboxylic acid with a polyol, or a poly-ε-caprolactone polyol obtained by ring-opening polymerization of ε-caprolactone. The polycarboxylic acid is preferably at least one selected from terephthalic acid, isophthalic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, octanoic acid, azelaic acid, sebacic acid, decamethyldicarboxylic acid, and dodecamethyldicarboxylic acid. The polyol is preferably at least one selected from ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, and cyclohexanediol. The polyether polyol can be at least one selected from random copolymers, block copolymers, and bisphenol-type polyoxyethylene modifiers of ethylene glycol, propylene glycol, tetrahydrofuran, 3-methyltetrahydrofuran, or their derivatives. The bisphenol-type polyoxyethylene modifier is a polyether polyol obtained by adding an epoxide to the active hydrogen portion of the bisphenol-type molecular backbone, and can be a random copolymer and / or a block copolymer. The epoxide is preferably at least one selected from ethylene oxide, propylene oxide, butane oxide, and isobutane oxide. The carbonate polyol may, by example, be at least one selected from 1,6-hexanediol polycarbonate, 1,4-butanediol-1,6-hexanediol polycarbonate, 1,5-pentanediol-1,6-hexanediol polycarbonate, caprolactone hexylene polycarbonate, 1,4-cyclohexanediol-1,6-hexanediol polycarbonate, ethylene carbonate polyol, propylene carbonate polyol, butylene carbonate polyol, and hexylene carbonate polyol. The polyalkylene polyol may, by example, be at least one selected from polybutadiene polyol, hydrogenated polybutadiene polyol, and hydrogenated polyisoprene polyol.

[0025] In this invention, the type and source of the polyisocyanate compound can be any of the existing options, preferably from at least one of isophorone diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, diphenylmethane-4,4'-diisocyanate, diphenylmethane-2,4'-diisocyanate, hydrogenated phenylenedimethylene diisocyanate, 1,5-naphthalene diisocyanate, 1,5-pentane diisocyanate, 1,4-phenylenedimethylene diisocyanate, m-phenylenedimethyl isocyanate, tetramethylphenylenedimethylene diisocyanate, norbornene diisocyanate, lysine diisocyanate, triphenylmethane triisocyanate, triphenyl thiophosphate triphenyl isocyanate, and 1,6,11-undecane triisocyanate.

[0026] In this invention, the type and source of the tackifying resin can be any of the existing options, preferably at least one of thermoplastic acrylic resin, polyurethane resin, rosin resin, petroleum resin, terpene resin, EVA resin, and amorphous polyolefin resin.

[0027] In this invention, the type and source of the silane coupling agent can be any of the existing options, preferably at least one of mercaptosilanes, epoxysilanes, aminosilanes, alkenylsilanes, and isocyanate-based silanes. Specific examples include, but are not limited to: 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropylmethyldiethoxysilane, 3-epoxypropoxypropyltrimethoxysilane, 3-epoxypropoxypropyltriethoxysilane, 3-epoxypropoxypropylmethyldimethoxysilane, 3-epoxypropoxypropylmethyldiethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-epoxy... At least one of the following: propoxypropylmethyldiethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-(2-aminoethyl)aminopropyltrimethoxysilane, 3-(2-aminoethyl)aminopropyltriethoxysilane, 3-(2-aminoethyl)aminopropylmethyldimethoxysilane, 3-(meth)acryloyloxypropyltrimethoxysilane, 3-(meth)acryloyloxypropylmethyldimethoxysilane, 3-(meth)acryloyloxypropylmethyldiethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, and 3-isocyanate propyltrimethoxysilane. The addition of a silane coupling agent helps promote the uniform dispersion of the solid electrolyte in the polyurethane hot melt adhesive system, thereby facilitating the electrolytic disintegration performance of the polyurethane hot melt adhesive system.

[0028] In this invention, the type and source of the catalyst can be any of the existing options, preferably at least one of dibutyltin dilaurate, stannous octoate, triethylamine, diethylenetriamine, triethylenediamine, N-ethylmorpholine, and 2,2-dimorpholinodiethyl ether.

[0029] In this invention, the type and source of the desiccant can be any of the existing options, preferably at least one of molecular sieve desiccant, oxazolidine desiccant, p-toluenesulfonyl isocyanate and triethyl orthoformate.

[0030] The method for preparing polyurethane hot melt adhesive provided by the present invention includes uniformly mixing a solid electrolyte, a polyol compound, a polyisocyanate compound, a silane coupling agent, and optionally a tackifying resin, a catalyst, and a water-absorbing agent to obtain a polyurethane hot melt adhesive. The present invention does not particularly limit the mixing conditions. In a preferred embodiment, the mixing method specifically includes the following steps: S1. Mixing the solid electrolyte, polyol compound, silane coupling agent, and optionally a tackifying resin and a water-absorbing agent, followed by vacuum dehydration treatment to obtain a pretreated product; S2. Mixing the pretreated product with a polyisocyanate compound and optionally a catalyst to obtain a polyurethane hot melt adhesive.

[0031] In the preparation process of the above-mentioned polyurethane hot melt adhesive, the vacuum dehydration conditions in step S1 include: the temperature is preferably 100-120℃, such as 100℃, 105℃, 110℃, 115℃, 120℃ or any value between them; the time is preferably 1-5h, such as 1h, 2h, 3h, 4h, 5h or any value between them; the stirring speed is preferably 100-200r / min, such as 100r / min, 120r / min, 150r / min, 180r / min, 200r / min or any value between them.

[0032] In the preparation process of the above-mentioned polyurethane hot melt adhesive, the mixing conditions in step S2 include: the temperature is preferably 70-90℃, such as 70℃, 75℃, 80℃, 85℃, 90℃ or any value between them; the time is preferably 1-5h, such as 1h, 2h, 3h, 4h, 5h or any value between them; the stirring speed is preferably 100-200r / min, such as 100r / min, 120r / min, 150r / min, 180r / min, 200r / min or any value between them.

[0033] The reactive polyurethane hot melt adhesive provided by this invention can be applied to electrically conductive adhesive substrates. The voltage for disassembly and energization can be 1–100V, such as 1V, 5V, 9V, 10V, 20V, 50V, 60V, 80V, 100V, or any value between them. The disassembly and energization time can be 1s–60min, such as 1s, 2s, 5s, 10s, 30s, 50s, 1min, 2min, 5min, 10min, 20min, 30min, 40min, 50min, 60min, or any value between them. Furthermore, the adhesive substrate used with the reactive polyurethane hot melt adhesive is a conductive substrate.

[0034] The present invention will be described in detail below through specific embodiments.

[0035] All parts mentioned in the following examples and comparative examples refer to parts by weight.

[0036] The raw materials and their sources in the following examples and comparative examples are as follows:

[0037] Polyhexyl adipate diol, purchased from Qingdao Xinyutian Chemical Co., Ltd., brand name POL-538, Mn = 3000 g / mol; polypropylene oxide ether diol, purchased from Dow Chemical Co., Ltd., brand name Voranol-2120, Mn = 2000 g / mol; polybutylene adipate diol, purchased from Qingdao Xinyutian Chemical Co., Ltd., brand name POL-3112, Mn = 1000 g / mol; polypentyl adipate diol, purchased from Qingdao Xinyutian Chemical Co., Ltd., brand name POL-756, Mn = 2000 g / mol; polycarbonate-1,5-pentanediol-1,6-hexanediol diol, purchased from Ube Industries Co., Ltd., brand name ETERNACOLL. PH-100, Mn = 1000 g / mol; Polycaprolactone diol, purchased from Perstorp, brand name CAPA-2200P, Mn = 2000 g / mol; Polytetrahydrofuran ether diol, purchased from PTG (Korea), brand name PTMEG 3000, Mn = 3000 g / mol; Polyhexyl adipate diol, purchased from Qingdao Xinyutian Chemical Co., Ltd., brand name POL-5112, Mn = 1000 g / mol; Polybutylene adipate diol, purchased from Qingdao Xinyutian Chemical Co., Ltd., brand name POL-356, Mn = 2000 g / mol.

[0038] NASICON-type oxide-based solid electrolyte LATP, D50 = 0.3 μm, purchased from Zhejiang Fengli New Energy Technology Co., Ltd., grade LATP-300, with an ionic conductivity ≥ 6*10 at room temperature. -4S / cm; Sulfide-based solid electrolyte FL-LPSC, D50 = 30μm, purchased from Zhejiang Fengli New Energy Technology Co., Ltd., grade LPSC-30000, ionic conductivity at room temperature 1*10⁻⁶. -2 S / cm; Garnet-type oxide-based solid electrolyte FL-GTEP, D50=0.5μm, purchased from Zhejiang Fengli New Energy Technology Co., Ltd., grade GTEP-500, ionic conductivity at room temperature ≥8*10 -4 S / cm; Sulfide-based solid electrolyte FL-LPSC, D90 = 20μm, purchased from Zhejiang Fengli New Energy Technology Co., Ltd., grade LPSC-20000, ionic conductivity at room temperature 6*10⁻⁶. -3 S / cm; NASICON type oxide-based solid electrolyte LATP, D50=0.6μm, purchased from Zhejiang Fengli New Energy Technology Co., Ltd., grade LATP-600, ionic conductivity at room temperature ≥6*10 -4 S / cm; NASICON type oxide-based solid electrolyte LATP, D50=0.1μm, purchased from Langu New Energy Technology Co., Ltd., grade LG1117, ionic conductivity at room temperature 5*10 -4 S / cm~1*10 -3 S / cm; Sulfide-based solid electrolyte LGPS, D50=50μm, purchased from Shenzhen ASML New Energy Co., Ltd., grade LGPS-50μm, ionic conductivity at room temperature ≥7*10 -3 S / cm; Polyethylene oxide (PEO) solid electrolyte, purchased from KELOD, grade E-30, with an ionic conductivity of 6.29*10 at room temperature. -6 S / cm.

[0039] p-Toluenesulfonyl isocyanate desiccant was purchased from Borchers GmbH, Germany, brand name Additive TI; triethyl orthoformate desiccant was purchased from Borchers GmbH, Germany, brand name Additive OF; molecular sieve desiccant was purchased from Arkema GmbH, brand name Siliporite SA1702.

[0040] Example 1

[0041] 40.22 parts of polyhexamethylene adipate diol POL-538 (Mn = 3000 g / mol), 22.98 parts of polyoxypropylene ether diol Voranol-2120 (Mn = 2000 g / mol), 10.00 parts of acrylic resin BR-106, 7.50 parts of NASICON type oxide-based solid electrolyte LATP (D50 = 0.3 μm), 7.00 parts of 3-mercaptopropyltrimethoxysilane, and 0.50 parts of water-absorbing agent Additive TI were added to a reaction flask, heated to 110°C, and vacuum dehydrated for 2 hours under stirring at 150 r / min. Then, the temperature was lowered to 80°C, and 11.49 parts of 4,4'-diphenylmethane diisocyanate (MDI) and 0.30 parts of stannous octoate were added. The mixture was reacted for 2 hours under stirring at 150 r / min, and the product was discharged to obtain polyurethane hot melt adhesive, which was then vacuum sealed and stored.

[0042] Example 2

[0043] 19.95 parts of polybutylene adipate diol POL-3112 (Mn = 1000 g / mol), 39.90 parts of polypentyl adipate diol POL-756 (Mn = 2000 g / mol), 10.00 parts of thermoplastic polyurethane resin Pearlbond 523, 5.00 parts of sulfide-based solid electrolyte FL-LPSC (D50 = 30 μm), 5.00 parts of 3-epoxypropoxypropyltrimethoxysilane, and 0.10 parts of water-absorbing agent Additive OF were added to a reaction flask and heated to 110°C. The mixture was then vacuum dehydrated for 2 hours under stirring at 150 r / min. The mixture was then cooled to 80°C, and 19.95 parts of 4,4'-diphenylmethane diisocyanate (MDI) and 0.10 parts of dibutyltin dilaurate were added. The mixture was reacted for 2 hours under stirring at 150 r / min to obtain polyurethane hot melt adhesive, which was then vacuum sealed and stored.

[0044] Example 3

[0045] The following ingredients were added: 15.80 parts of polycarbonate-1,5-pentanediol-1,6-hexanediol ester diol ETERNACOLL PH-100 (Mn = 1000 g / mol), 31.59 parts of polycaprolactone diol CAPA-2200P (Mn = 2000 g / mol), 15.00 parts of acrylic resin BM751, 15.00 parts of garnet-type oxide-based solid electrolyte FL-GTEP (D50 = 0.5 μm), 10.00 parts of 3-epoxypropoxypropyltrimethoxysilane, and 1.00 part of water-absorbing agent Siliporite. SA1702 was added to a reaction flask and heated to 110°C. The mixture was then vacuum dehydrated for 2 hours under stirring at 150 rpm. The temperature was then lowered to 80°C, and 10.61 parts of hexamethylene diisocyanate (HDI) and 1.00 parts of 2,2-dimorpholinodiethyl ether were added. The mixture was then reacted for 2 hours under stirring at 150 rpm to obtain polyurethane hot melt adhesive, which was then vacuum sealed and stored.

[0046] Example 4

[0047] 43.15 parts of polytetrahydrofuran ether diol PTMEG 3000 (Mn = 3000 g / mol), 14.38 parts of polyhexyl adipate diol POL-5112 (Mn = 1000 g / mol), 8.00 parts of amorphous polyolefin APAO resin VESTOPLAST 520, 10.00 parts of sulfide-based solid electrolyte FL-LPSC (D90 = 20 μm), 8.50 parts of vinyltrimethoxysilane, and 1.20 parts of water-absorbing agent Additive TI were added to a reaction flask, heated to 110°C, and vacuum dehydrated for 2 hours under stirring at 150 r / min. Then, the temperature was lowered to 80°C, and 12.77 parts of isophorone diisocyanate (IPDI) and 2.00 parts of dibutyltin dilaurate were added. The mixture was reacted for 2 hours under stirring at 150 r / min, and the product was discharged to obtain polyurethane hot melt adhesive, which was then vacuum sealed and stored.

[0048] Example 5

[0049] 26.90 parts of polyoxypropylene ether diol Voranol-2120 (Mn = 2000 g / mol), 26.90 parts of polybutylene adipate diol POL-356 (Mn = 2000 g / mol), 12.00 parts of thermoplastic polyurethane resin Pearlbond 539, 11.00 parts of NASICON type oxide-based solid electrolyte LATP (D50 = 0.6 μm), 6.80 parts of 3-mercaptopropyltrimethoxysilane, and 0.80 parts of water-absorbing agent Additive OF were added to a reaction flask, heated to 110°C, and vacuum dehydrated for 2 hours under stirring at 150 r / min. Then, the temperature was lowered to 80°C, and 14.10 parts of 4,4-diisocyanate dicyclohexylmethane (HMDI) and 1.50 parts of stannous octoate were added. The mixture was reacted for 2 hours under stirring at 150 r / min, and the product was discharged to obtain polyurethane hot melt adhesive, which was then vacuum sealed and stored.

[0050] Example 6

[0051] 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 = 0.1 μm was used instead of NASICON-type oxide-based solid electrolyte LATP with D50 = 0.3 μm. All other conditions were the same as in Example 1. Polyurethane hot melt adhesive was thus prepared and stored in a vacuum-sealed container.

[0052] Example 7

[0053] 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=0.3μm. All other conditions were the same as in Example 1. Polyurethane hot melt adhesive was thus prepared.

[0054] Comparative Example 1

[0055] The reference polyurethane hot melt adhesive was prepared according to the method of Example 1, except that the NASICON-type oxide-based solid electrolyte LATP (D50 = 0.3 μm) was not added. All other conditions were the same as in Example 1. The reference polyurethane hot melt adhesive was thus prepared and stored under vacuum.

[0056] Comparative Example 2

[0057] The reference polyurethane hot melt adhesive was prepared according to the method of Example 1, except that the amount of NASICON-type oxide-based solid electrolyte LATP (D50 = 0.3 μm) added was reduced to 1.00 parts, and all other conditions were the same as in Example 1. The reference polyurethane hot melt adhesive was thus prepared and stored in a vacuum-sealed container.

[0058] Comparative Example 3

[0059] The reference polyurethane hot melt adhesive was prepared according to the method of Example 1, except that the amount of 3-mercaptopropyltrimethoxysilane added was reduced to 1.0 part, and the other conditions were the same as in Example 1. The reference polyurethane hot melt adhesive was thus prepared and stored in a vacuum-sealed container.

[0060] Comparative Example 4

[0061] 34.03 parts of polyhexanediol adipate diol POL-538 (Mn = 3000 g / mol), 19.45 parts of polyoxypropylene ether diol Voranol-2120 (Mn = 2000 g / mol), 10.00 parts of acrylic resin BR-106, 7.50 parts of lithium trifluoromethanesulfonate, 17.50 parts of propylene carbonate, and 0.50 parts of water-absorbing agent Additive TI were added to a reaction flask and heated to 110°C. The mixture was then vacuum dehydrated for 2 hours under stirring at 150 r / min. The temperature was then lowered to 80°C, and 9.72 parts of 4,4'-diphenylmethane diisocyanate (MDI) and 0.30 parts of stannous octoate were added. The mixture was reacted for 2 hours under stirring at 150 r / min, and the product was discharged to obtain a reference polyurethane hot melt adhesive containing liquid electrolyte. The adhesive was then vacuum sealed and stored.

[0062] Comparative Example 5

[0063] The reference polyurethane hot melt adhesive was prepared according to the method in Example 1, except that a polyethylene oxide (PEO) solid electrolyte (Clude Chemicals, brand E-30, with an ionic conductivity of 6.29 × 10⁻⁶ at room temperature) was used. -6 The reference polyurethane hot melt adhesive was prepared by replacing the NASICON-type oxide-based solid electrolyte LATP (D50 = 0.3 μm) with S / cm, and keeping all other conditions the same as in Example 1.

[0064] Test case

[0065] The polyurethane hot melt adhesives prepared in the above examples and comparative examples were tested for adhesion performance, heat resistance, and high temperature and high humidity resistance before and after energization using the following methods. The results are shown in Table 1.

[0066] (1) Bonding strength test at different curing times before power-on: The polyurethane hot melt adhesive obtained in the examples and comparative examples was applied at 110°C using a dispensing machine to apply a rectangular adhesive line of 25mm*4mm on the stainless steel substrate; then, another stainless steel substrate was bonded to the stainless steel substrate. After bonding, the sample was cured in an environment of 25°C and 50%RH for 30min and 1d respectively. Then, the bonded sample was run along the shear direction at a speed of 10mm / min until the bond failed using a universal testing machine. The maximum force value displayed by the instrument was recorded. The shear bond strength of the adhesive to the stainless steel substrate after curing for 30min and 1d was calculated in combination with the bonding area.

[0067] (2) Bonding strength after energization: After curing the adhesive for 1 day according to the method in (1), the sample to be tested was obtained. The positive and negative wires of the DC power supply were clamped at both ends of the sample. The sample was energized at 48V for 30 minutes or at 60V for 20 minutes. After the energization was completed, the sample was removed. The bonded sample was run along the shear direction at a speed of 10mm / min using a universal testing machine until the bond of the sample failed. The maximum force value displayed by the instrument was recorded. The shear bond strength of the adhesive to the stainless steel substrate after energization was calculated in combination with the bonding area (when the bond strength is below 2MPa, it is detachable).

[0068] (3) Heat resistance (80℃): After curing the adhesive for 1 day according to the method in (1), the sample to be tested was obtained. The sample to be tested was placed in an oven at 80℃ for 20 minutes. The bonded sample was then placed in an environment at 80℃ and run along the shear direction at a speed of 10 mm / min until the bond of the sample failed. The maximum force value displayed by the instrument was recorded. The shear bond strength of the adhesive to the stainless steel substrate under the high temperature environment of 80℃ was calculated in combination with the bonding area.

[0069] (4) High temperature and high humidity resistance (85℃, 85%RH): After curing the adhesive for 1 day according to the method in (1), the sample to be tested was obtained. The sample to be tested was placed in a high temperature and high humidity oven at 85℃ and 85%RH for 7 days. The bonded sample was then run along the shear direction at a speed of 10mm / min until the bond failed. The maximum force value displayed by the instrument was recorded. The shear bond strength of the adhesive to the stainless steel substrate after high temperature and high humidity aging was calculated in combination with the bonding area.

[0070] Table 1

[0071] The results of Examples 1-7 show that the polyurethane hot melt adhesive provided by the present invention not only exhibits a significant decrease in bonding strength (below 2 MPa) after energization, thus possessing removability, but also demonstrates fast curing speed, high bonding strength, and excellent heat resistance, high temperature and humidity resistance, and superior adhesive performance. The results of Examples 1 and Comparative Examples 1, 2, and 5 indicate that without the addition of oxide-based or sulfide-based solid electrolytes, or with insufficient amounts of solid electrolytes, or with the addition of polymer-based solid electrolytes, the bonding strength of the polyurethane hot melt adhesive after energization is far higher than 2 MPa, lacking removability. Simultaneously, the bonding strength, heat resistance, and high temperature and humidity resistance of the polyurethane hot melt adhesive before energization are reduced. The results of Examples 1 and Comparative Example 3 show that with insufficient amounts of silane coupling agent, the bonding strength, heat resistance, and high temperature and humidity resistance of the polyurethane hot melt adhesive are poor, and the bonding strength decreases less after energization, remaining above 2 MPa, but lacking removability. As can be seen from the results of Example 1 and Comparative Example 4, compared with the traditional electrically disintegratable polyurethane hot melt adhesives made by adding alkali metal salts and solvating matrix, the polyurethane hot melt adhesive provided in Example 1 not only has the same electrically disintegratable properties, but also has the advantages of fast curing speed, excellent bonding performance, and good heat resistance and high temperature and humidity resistance.

[0072] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A polyurethane hot melt adhesive, characterized in that, The raw materials for preparing the polyurethane hot melt adhesive contain a solid electrolyte, a polyol compound, a polyisocyanate compound, a silane coupling agent, and optional tackifying resin, catalyst, and water absorbent; the solid electrolyte is an oxide-based solid electrolyte and / or a sulfide-based solid electrolyte; the mass ratio of the solid electrolyte, polyol compound, and silane coupling agent is (5-35):100:(5-25).

2. The polyurethane hot melt glue according to claim 1, characterized in that, The solid electrolyte is present in a content of 5-15 parts by weight, the polyol compound in a content of 45-65 parts by weight, the polyisocyanate compound in a content of 10-20 parts by weight, the silane coupling agent in a content of 5-10 parts by weight, the tackifying resin in a content of 0-15 parts by weight, the catalyst in a content of 0-2 parts by weight, and the water absorbent in a content of 0-2 parts by weight.

3. The polyurethane hot melt glue according to claim 1, characterized in that, The solid-state electrolyte has an ionic conductivity of 10 -4 S / cm or more at room temperature.

4. The polyurethane hot melt glue of claim 1, wherein, The solid electrolyte has a D50 or D90 particle size of 0.3–30 μm.

5. The polyurethane hot melt glue of claim 1, wherein, The number-average molecular weight of the polyol compound is 1000-4000 g / mol; the polyol compound is selected from at least one of polyester polyol, polyether polyol, polycarbonate polyol and polyalkylene polyol.

6. The polyurethane hot melt glue of claim 1, wherein, The polyisocyanate compound is selected from at least one of isophorone diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, diphenylmethane-4,4'-diisocyanate, diphenylmethane-2,4'-diisocyanate, hydrogenated phenylenedimethylene diisocyanate, 1,5-naphthalene diisocyanate, 1,5-pentane diisocyanate, 1,4-phenylenedimethylene diisocyanate, m-phenylenedimethyl isocyanate, tetramethylphenylenedimethylene diisocyanate, norbornene diisocyanate, lysine diisocyanate, triphenylmethane triisocyanate, triphenyl thiophosphate triphenyl isocyanate, and 1,6,11-undecane triisocyanate.

7. The polyurethane hot melt glue of claim 1, wherein, The tackifying resin is selected from at least one of thermoplastic acrylic resin, polyurethane resin, rosin resin, petroleum resin, terpene resin, EVA resin, and amorphous polyolefin resin.

8. The polyurethane hot melt glue of claim 1, wherein, The silane coupling agent is selected from 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropylmethyldiethoxysilane, 3-epoxypropoxypropyltrimethoxysilane, 3-epoxypropoxypropyltriethoxysilane, 3-epoxypropoxypropylmethyldimethoxysilane, 3-epoxypropoxypropylmethyldiethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-epoxypropoxypropylmethyldiethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltriethoxysilane, 3-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-epoxypropoxypropylmethyldiethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-epoxypropoxypropylmethyldiethoxysilane, 3-aminopropyltriethoxysilane, 3-epoxypropoxypropylmethyldiethoxysilane, 3-epoxypropoxypropylmethyldiethoxysilane, 3-epoxypropoxypropyltri ... At least one of the following: oxysilane, 3-(2-aminoethyl)aminopropyltrimethoxysilane, 3-(2-aminoethyl)aminopropyltriethoxysilane, 3-(2-aminoethyl)aminopropylmethyldimethoxysilane, 3-(meth)acryloyloxypropyltrimethoxysilane, 3-(meth)acryloyloxypropyltriethoxysilane, 3-(meth)acryloyloxypropylmethyldimethoxysilane, 3-(meth)acryloyloxypropylmethyldiethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, and 3-isocyanate propyltrimethoxysilane; The catalyst is selected from at least one of dibutyltin dilaurate, stannous octoate, triethylamine, diethylenetriamine, triethylenediamine, N-ethylmorpholine, and 2,2-dimorpholinodiethyl ether; The desiccant is selected from at least one of molecular sieve desiccant, oxazolidine desiccant, p-toluenesulfonyl isocyanate and triethyl orthoformate.

9. The method of making the polyurethane hot melt adhesive of claim 1, characterized in that, The method involves uniformly mixing a solid electrolyte, a polyol compound, a polyisocyanate compound, a silane coupling agent, and optionally a tackifying resin, a catalyst, and a water-absorbing agent to obtain a polyurethane hot melt adhesive.

10. The application of the polyurethane hot melt adhesive according to claim 1 in the bonding of electronic products.

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