A polyurethane material for solid-state battery packaging and preparation method thereof

Abstract

The present invention discloses a polyurethane material for solid-state battery packaging and its preparation method, relating to the field of polymer material technology. The polyurethane material comprises the following components: a polyol, a polyisocyanate, a chain extender, a reinforcing agent, a catalyst, and an auxiliary agent. The polyurethane material comprises three components: A, B, and C. Component A comprises the following components by weight: 90-100 parts chain extender, 1-2 parts catalyst, 1-2 parts antioxidant, 1-3 parts silicone oil, and 1-3 parts water; Component B comprises the following components by weight: 40-50 parts polyisocyanate, 0.005 parts polymerization inhibitor, and 45-70 parts polyol; and Component C is the reinforcing agent. By designing the polyurethane formula and using surface-modified carbon fiber as a reinforcing agent, the present invention significantly improves the compressive strength and recovery properties of the polyurethane material, resulting in a polyurethane material with high compressive strength and recovery properties, as well as high strength, toughness, and aging resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and in particular to a polyurethane material for solid-state battery packaging and a preparation method thereof. Background Art

[0002] Solid-state batteries are a type of battery technology. Unlike the lithium-ion and lithium-ion polymer batteries commonly used today, solid-state batteries use solid electrodes and solid electrolytes. Since the scientific community believes that lithium-ion batteries have reached their limits, solid-state batteries have recently been seen as a potential successor to lithium-ion batteries. The core advantages of automotive solid-state batteries lie in their high energy density, strong safety, and fast charging speeds. However, they currently face challenges such as high costs and low technological maturity. Solid-state batteries change volume during charging and discharging, and the gaps between cells are small, resulting in high pressure from deformation. Therefore, these gaps require materials with high pressure resistance and good dimensional recovery. Compared to other materials, polyurethanes are widely used in various fields due to their excellent mechanical properties, rebound performance, and processing characteristics, as well as their flexible formulation design. Therefore, we propose a polyurethane material for solid-state battery encapsulation and its preparation method. Summary of the Invention

[0003] The purpose of the present invention is to provide a polyurethane material for solid-state battery packaging and a preparation method thereof. Through a special raw material formula and preparation process, the compressive strength of the polyurethane material is significantly improved while maintaining good compression recovery performance, so as to solve the problems raised in the above background technology.

[0004] In order to solve the above technical problems, the present invention provides the following technical solution: A polyurethane material for solid-state battery encapsulation, comprising the following components: polyol, polyisocyanate, chain extender, reinforcing agent, catalyst and auxiliary agent.

[0005] Furthermore, the auxiliary agents include stabilizers, antioxidants, silicone oil and polymerization inhibitors.

[0006] Furthermore, the polyurethane material includes three components A, B, and C;

[0007] The components of component A are as follows: 90-100 parts by mass of a chain extender, 1-2 parts by mass of a catalyst, 1-2 parts by mass of an antioxidant, 1-3 parts by mass of a silicone oil, and 1-3 parts by mass of water;

[0008] The B component comprises the following components: 40 to 50 parts by mass of polyisocyanate, 0.005 parts by mass of polymerization inhibitor, and 45 to 70 parts by mass of polyol;

[0009] The C component is a reinforcing agent.

[0010] Furthermore, the mass ratio of component A, component B and component C is 100:(10-15):(4-12).

[0011] Furthermore, the polyol is a mixture of one or more of polycarbonate polyol, polyester polyol and polyether polyol;

[0012] The polyisocyanate is one of 4,4'-diphenylmethane diisocyanate and isophorone diisocyanate or a mixture of the two;

[0013] The chain extender is one of 1,4-butanediol and glycerol or a mixture of the two.

[0014] Furthermore, the reinforcing agent is inorganic fiber.

[0015] Furthermore, the chain extender includes 90 to 95 parts of 1,4-butanediol and 0 to 5 parts of glycerol, calculated by mass.

[0016] Furthermore, the catalyst includes, by weight, 0.5 to 1 parts of triethylenediamine dipropylene glycol solution and 0.5 to 1 parts of bis(dimethylaminoethyl) ether and dipropylene glycol solution.

[0017] Furthermore, the polyisocyanate is 4,4'-diphenylmethane diisocyanate.

[0018] Furthermore, the polyol is polytetramethylene ether glycol,

[0019] The polytetramethylene ether diol comprises 30-40 parts of low-molecular-weight tetramethylene ether diol (Mn=2000) and 15-30 parts of high-molecular-weight tetramethylene ether diol (Mn=1000).

[0020] Furthermore, the reinforcing agent is a surface-treated carbon fiber. The reinforcing agent is a compressive strength enhancer that can be evenly dispersed in polyurethane and form chemical adhesion therewith, effectively improving the compressive strength of the prepared polyurethane material.

[0021] A method for preparing a polyurethane material for solid-state battery packaging, comprising the following steps:

[0022] Step 1. Synthesis of prepolymer: Heat and melt polyisocyanate, add polymerization inhibitor and polyol, and heat to react to obtain prepolymer, which is recorded as component B;

[0023] Step 2. Preparing a reinforcing agent: oxidizing the carbon fiber in nitric acid to obtain oxidized carbon fiber; reacting the oxidized carbon fiber in a mixture of thionyl chloride and N,N-dimethylformamide to obtain chlorinated carbon fiber; and reacting the chlorinated carbon fiber in a mixture of triethylamine and monoethanolamine in tetrahydrofuran to obtain a modified carbon fiber, i.e., a reinforcing agent, recorded as component C;

[0024] Step 3. Mixing: Disperse the chain extender, additives and water at high speed to obtain component A; mix component A, component B and component C and stir at high speed to obtain a mixture;

[0025] Step 4. Molding and aging: The mixture is injected into the mold, cured and shaped, taken out, and aged to obtain the polyurethane material.

[0026] Furthermore, the process of step 1 is as follows:

[0027] Heat the polyisocyanate at 40-80°C until it melts, add the polymerization inhibitor and mix; slowly add the polyol within 20-40 minutes, and then stir the reaction at 70-80°C for 150-200 minutes. Stop the reaction when the NCO value is 13±0.5% to obtain a prepolymer, which is recorded as component B.

[0028] Furthermore, the stirring speed is 300 to 500 rpm;

[0029] Before use, the polyol was vacuum dehydrated at 120° C. for 2 h to reduce its moisture content to less than 0.05%, and then cooled to 70° C. for standby use.

[0030] Furthermore, the process of step 2 is as follows:

[0031] The carbon fibers were placed in nitric acid at 100°C for oxidation reaction for 100-150 minutes; then taken out, washed several times with distilled water, and dried at 100°C to obtain oxidized carbon fibers;

[0032] The oxidized carbon fiber is placed in a mixture of thionyl chloride and N,N-dimethylformamide, and reacted at a temperature of 38 to 42° C. for 200 to 280 minutes; after the reaction, excess thionyl chloride is removed to obtain chlorinated carbon fiber;

[0033] The chlorinated carbon fiber is placed in a mixture of triethylamine and monoethanolamine in tetrahydrofuran and reacted for 200 to 280 minutes; then washed with anhydrous ethanol and dried in an oven at 80°C for 2 hours to obtain a modified carbon fiber, i.e., a reinforcing agent, which is recorded as component C.

[0034] Furthermore, in the mixture of thionyl chloride and N,N-dimethylformamide, the volume ratio of thionyl chloride to N,N-dimethylformamide is 1:100;

[0035] In the tetrahydrofuran mixture of triethylamine and monoethanolamine, the mass ratio of triethylamine, monoethanolamine and tetrahydrofuran is 2:1:3.

[0036] Furthermore, the mass ratio of carbon fiber to nitric acid is 1:(10-20); and the concentration of nitric acid is 65-68wt%.

[0037] Furthermore, the mass ratio of the oxidized carbon fiber, thionyl chloride and N,N-dimethylformamide mixed solution is 1:(15-25).

[0038] Furthermore, the mass ratio of the chlorinated carbon fiber, triethylamine and monoethanolamine in tetrahydrofuran is 1: (2.5-3.0).

[0039] Furthermore, before use, the carbon fiber was cleaned with acetone, washed with distilled water, and dried.

[0040] Furthermore, in step 3, the process conditions for high-speed dispersion are: a rotation speed of 1000-1500 rpm and a duration of 10-15 minutes;

[0041] The process conditions for high-speed stirring are: rotation speed 800-1200 rpm, duration 5-8 min.

[0042] Furthermore, in step 4, the curing process conditions are: temperature 100±5°C, time 30 to 60 minutes;

[0043] The aging process conditions are: temperature 110±5℃, time 6 to 10 hours.

[0044] In the above technical solution, carbon fibers are oxidized under the action of nitric acid, and polar functional groups such as carboxyl (-COOH) and hydroxyl (-OH) are introduced on the surface of the carbon fibers to increase the surface activity of the carbon fibers. The resulting oxidized carbon fibers are then dispersed in a thionyl chloride solution, whereby the carboxyl groups react with the thionyl chloride to generate highly active acyl chloride groups on the carbon fiber surface, facilitating subsequent amination grafting. Finally, the acyl chloride groups on the surface of the chlorinated carbon fibers react with the amino groups (-NH2) in monoethanolamine to graft long-chain molecules containing hydroxyl (-OH) groups onto the surface of the carbon fibers, enhancing the compatibility between the carbon fibers and the polyurethane resin. The resulting modified carbon fibers are evenly dispersed in the polyurethane resin, avoiding agglomeration. The modified carbon fibers contain hydroxyl groups on their surface, which can form hydrogen bonds and covalent bonds with the polyurethane prepolymer (-NCO), effectively improving the interfacial bonding strength between the two. The rigid skeleton of the carbon fibers and the elasticity of the polyurethane resin work synergistically to effectively improve the compressive strength and recovery of the resulting polyurethane material.

[0045] In this technical solution, polyisocyanate reacts with polytetramethylene glycol (PTMEG) to form a prepolymer (component B) containing -NCO groups. The chain extender 1,4-butanediol reacts with the -NCO groups in the prepolymer to form hard segments, and glycerol introduces crosslinking points to construct a three-dimensional network within the polyurethane resin. The hydroxyl groups on the surface of the reinforcing agent react with the -NCO groups to form chemical bonds and physical entanglements, reinforcing the polyurethane material. The rigidity provided by the hard segments (MDI-chain extender), the elasticity provided by the soft segments (PTMEG), and the further reinforcement provided by modified carbon fibers significantly enhance the compressive strength and recovery of the resulting polyurethane material. The chemically bonded carbon fiber-polyurethane resin interface exhibits excellent interfacial stability, effectively suppressing stress cracking during battery charge and discharge. The dense crosslinked network, synergistically with antioxidants, delays degradation of the polyurethane material in the solid-state battery environment (high temperature and electrolyte exposure), improving its aging resistance and extending its service life. The resulting polyurethane material can adapt to the volume changes and thermal cycling of solid-state batteries, exhibiting high packaging reliability. Moreover, the preparation of polyurethane materials is a step-by-step synthesis process with stable process and strong parameter controllability. It has industrial feasibility and is suitable for solid-state battery packaging scenarios that require high mechanical strength, high resilience and long-term stability.

[0046] Furthermore, the chain extender may be a polyhydroxy compound or a combination thereof with 1,4-butanediol;

[0047] The polyol is prepared by the following process:

[0048] (1) p-Hydroxybenzaldehyde, epichlorohydrin, and tetrabutylammonium bromide were mixed and refluxed at 70-80°C for 4-6 hours under a nitrogen atmosphere; after the reaction, the mixture was cooled to room temperature and an aqueous sodium hydroxide solution was added within 1 hour; the mixture was heated to 50-60°C and refluxed for 4-6 hours; the mixture was cooled to room temperature, the organic layer was diluted with dichloromethane, washed with water, and rotary evaporated to obtain an aldehyde-containing epoxy compound;

[0049] (2) Mix the aldehyde-containing epoxy compound and diazolidinyl urea in a solvent, add triethylamine and a catalyst, and heat to 25-40°C under nitrogen atmosphere, stirring and reacting for 4-6 hours; after the reaction, cool to room temperature, add saturated sodium bicarbonate solution, separate the liquids, take the organic phase, dry it with anhydrous magnesium sulfate, filter, rotary evaporate, and chromatograph to obtain the aldehyde compound;

[0050] (3) Mix the aldehyde compound and acetonitrile, add the fluorine-containing amino compound, and react at 60-80°C for 6-10 hours under nitrogen atmosphere to form a Schiff base. After the reaction is completed, cool to room temperature, wash, and vacuum dry to form a Schiff base to obtain a polyhydroxy compound.

[0051] Furthermore, in step (1), the mass ratio of p-hydroxybenzaldehyde, epichlorohydrin, and tetrabutylammonium bromide is 10:(7.6-15.2):(2.5-3.0);

[0052] The concentration of the sodium hydroxide aqueous solution is 20-40wt%, and the amount used is 1.0-1.5 times the mass of p-hydroxybenzaldehyde.

[0053] Furthermore, in step (2), the mass ratio of the aldehyde-containing epoxy compound to the diazolidinyl urea is 10:(11.9-15.7);

[0054] The ratio of aldehyde-containing epoxy compound to solvent is (15-25) g / 100 mL;

[0055] The solvent is a mixed solvent of DMF (N,N-dimethylformamide) and THF (tetrahydrofuran), with a volume ratio of 1:1;

[0056] The dosages of triethylamine (alkaline additive) and catalyst (tin tetrachloride) are 0.52-0.85% and 6.9-9.1% respectively (relative to the mass of the aldehyde-containing epoxy compound).

[0057] Furthermore, in step (3), the fluorine-containing amino compound is one of 4-(trifluoromethyl)aminocyclohexane, 4,4-difluoroaminoethylpiperidine, 4,4'-[1,4-phenylbis(oxy)]bis[3-(trifluoromethyl)aniline] (6FAPB), 1,6-diamino-2,2,3,3,4,4,5,5-octafluorohexane (8F-HDA), and bis(3-aminopropyl)-tetramethyldisiloxane hexafluoro derivative;

[0058] The mass ratio of the aldehyde compound to the fluorinated amino compound is 10:(3.6-9.4);

[0059] The ratio of aldehyde compound to acetonitrile is (15-25) g / 100 mL.

[0060] In the above technical solution, in step (1), under the action of tetramethylammonium bromide as a catalyst, p-hydroxybenzaldehyde and epichlorohydrin undergo a Williamson ether synthesis reaction to generate an epoxy ether compound containing an aldehyde group, and the aldehyde group is retained. The obtained product is recorded as an aldehyde-containing epoxy compound. Then, the epoxy group in the aldehyde-containing epoxy compound reacts with diazolidinyl urea to obtain an aldehyde compound. Finally, the obtained aldehyde compound is mixed with a fluorine-containing amino compound, so that the aldehyde group and the amino group undergo a condensation reaction to generate a Schiff base, thereby obtaining the desired polyhydroxy compound. When the prepared polyhydroxy compound is used as a chain extender in a polyurethane material, (1) for mechanical properties: its polyhydroxy structure can react with isocyanate (-NCO) to form a three-dimensional cross-linked network, thereby increasing the cross-linking density of the polyurethane resin; and the rigidity contributed by the structure such as imidazole is synergistically improved, thereby improving the hardness and tear resistance of the material. The fluorine-containing amino compound includes perfluorohexane, trifluoromethyl, etc., which introduces a flexible fluorine segment, which can offset the brittleness caused by cross-linking and improve the impact resistance of the polyurethane material. (2) Regarding thermal properties: The strong bond energy of the fluorinated groups and the high thermal stability of the imidazole ring can improve the high-temperature resistance of the polyurethane material by increasing the decomposition temperature; and the introduction of rigid structures such as imidazole and the combination of the cross-linked network can reduce the slippage of the molecular chain at high temperatures, further improving the high-temperature resistance of the prepared polyurethane material. (3) Regarding electrochemical properties: The fluorinated groups reduce the polarity of the polyurethane material, reducing its dielectric constant and effectively reducing the battery polarization effect; and the high electronegativity of the fluorine atom can inhibit charge accumulation and increase the volume resistivity. (4) Others: The fluorinated segments and imidazole rings improve the lyophobicity of the polyurethane, helping to inhibit the penetration of the electrolyte and alleviate swelling; and the -C=N bond in the Schiff base structure can form a weak coordination with the battery electrode (such as lithium), balancing the bonding strength and interfacial impedance, and improving the interfacial stability. The fluorinated segments make the polyurethane material water-resistant, and the chemical inertness and UV absorption ability of imidazole enable it to maintain good mechanical properties after wet heat and UV aging, improving its tolerance to the environment.

[0061] Furthermore, in the preparation of the modified carbon fiber, monoethanolamine can be replaced by a polyhydroxy compound, and the preparation process of the modified carbon fiber is as follows:

[0062] The chlorinated carbon fiber is placed in a dichloromethane mixture of a catalyst and a polyhydroxy compound and reacted for 120 to 180 minutes; then washed with dilute hydrochloric acid and anhydrous ethanol, and dried in an oven at 80°C for 2 hours to obtain a modified carbon fiber, i.e., a reinforcing agent, recorded as component C.

[0063] Furthermore, the catalyst is a mixture of DCC (dicyclohexylcarbodiimide) and DMAP (4-dimethylaminopyridine) in a molar ratio of 4:1;

[0064] In the dichloromethane mixed liquid of the catalyst and the polyhydroxy compound, the mass ratio of the catalyst, the polyhydroxy compound and the dichloromethane is (0.1-0.2):1:(3-5).

[0065] The mass ratio of the chlorinated carbon fiber, the catalyst and the dichloromethane mixed liquid of the polyhydroxy compound is 1: (2.5-3.0).

[0066] Furthermore, in the preparation of the modified carbon fiber, monoethanolamine can be replaced by diazolidinyl urea.

[0067] In the above technical solution, under the action of a catalyst, the polyhydroxy compound and the acyl chloride group in the acyl chloride carbon fiber undergo esterification, and polyhydroxy groups, imidazole rings and other structures are introduced on the surface of the carbon fiber. The isocyanate (-NCO) in the polyurethane prepolymer forms a covalent bond with the hydroxyl (-OH) on the surface of the modified carbon fiber, and the nitrogen-containing functional group forms a hydrogen bond with the carbonyl group, amine group and other groups in the polyurethane chain segment, which effectively improves the interfacial strength between the carbon fiber and the polyurethane resin; and cooperates with the rigidity of the imidazole ring to inhibit the interfacial slip between the carbon fiber and the polyurethane resin, further improving the tensile and compressive mechanical properties of the prepared polyurethane material. The thermal stability, hydrophobicity and hydrogen bond repair ability of the imidazole ring and the nitrogen-containing structure improve the high temperature stability of the polyurethane material and improve its resistance to wet heat aging. (3) Regarding electrochemical properties: Compared with monoethanolamine, the polarity of the modified carbon fiber surface is reduced, making its dielectric constant lower, which helps to reduce dielectric loss.

[0068] Compared with the prior art, the present invention has the following beneficial effects:

[0069] The polyurethane material for solid-state battery packaging described in the present invention significantly improves the compressive strength and recovery performance of the polyurethane material by designing the polyurethane formula and using surface-modified carbon fiber as a reinforcing agent. The polyurethane material has high compressive strength and high recovery performance while also having high strength, toughness and aging resistance. DETAILED DESCRIPTION

[0070] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0071] In the following specific embodiments,

[0072] Chain extender: 1,4-butanediol (BDO), technical grade, sourced from BASF; glycerol, technical grade, sourced from Musim Mas;

[0073] Catalysts: triethylenediamine dipropylene glycol solution (A33), technical grade, sourced from Huntsman; bis(dimethylaminoethyl) ether in dipropylene glycol solution (BL11), technical grade, sourced from Air Products and Chemicals;

[0074] Antioxidant: Antioxidant 168, industrial grade, from BASF;

[0075] Silicone oil: Y10366, industrial grade, from Momentive;

[0076] Water: purified water;

[0077] Polyisocyanate: MDI-100, industrial grade, sourced from Wanhua Chemical;

[0078] Inhibitor: phosphoric acid, analytical grade, from Pratt & Whitney Chemical;

[0079] Polytetramethylene glycol: Mn=2000, Mn=1000, from Hyosung, South Korea, vacuum dried at 120℃ for 2h before use, moisture content <5%, cooled to 70℃, and set aside;

[0080] Carbon fiber, sourced from DuPont, was cleaned with acetone, rinsed with distilled water, and dried before use;

[0081] In the mixture of thionyl chloride and N,N-dimethylformamide, the volume ratio of thionyl chloride to N,N-dimethylformamide is 1:100;

[0082] In the mixture of triethylamine and monoethanolamine in tetrahydrofuran, the mass ratio of triethylamine, monoethanolamine and tetrahydrofuran is 2:1:3;

[0083] The nitric acid concentration was 67 wt%.

[0084] Example 1: A method for preparing a polyurethane material for solid-state battery packaging, comprising the following steps:

[0085] Step 1. Synthesis of prepolymer: Heat polyisocyanate at 60°C until melted, add polymerization inhibitor and mix; slowly add polyol within 40 minutes, then stir at 75°C for 180 minutes at 300 rpm. Stop the reaction when the NCO value reaches 13% to obtain a prepolymer, recorded as component B.

[0086] Step 2. Preparation of a reinforcing agent: The carbon fibers were placed in nitric acid at 100°C for oxidation reaction for 120 minutes; the carbon fibers were then taken out, washed several times with distilled water, and dried at 100°C to obtain oxidized carbon fibers; the mass ratio of carbon fibers to nitric acid was 1:10;

[0087] The oxidized carbon fibers were placed in a mixture of thionyl chloride and N,N-dimethylformamide and reacted at 40°C for 240 minutes; after the reaction, excess thionyl chloride was removed to obtain chlorinated carbon fibers; the mass ratio of the oxidized carbon fibers, thionyl chloride and N,N-dimethylformamide mixture was 1:15;

[0088] The chlorinated carbon fibers were placed in a mixture of triethylamine and monoethanolamine in tetrahydrofuran and reacted for 240 minutes. The mixture was then washed with anhydrous ethanol and dried in an oven at 80°C for 2 hours to obtain a modified carbon fiber, i.e., a reinforcing agent, which was designated as component C. The mass ratio of the chlorinated carbon fibers to the mixture of triethylamine and monoethanolamine in tetrahydrofuran was 1:2.5.

[0089] Step 3. Mixing: Disperse the chain extender, the auxiliary agent and water at high speed to obtain component A; mix component A, component B and component C and stir them at high speed to obtain a mixture; the process conditions for high-speed dispersion are: speed 1000 rpm, time 15 minutes; the process conditions for high-speed stirring are: speed 800 rpm, time 8 minutes; the following components of component A are as follows: 90 parts by weight of chain extender, 1 part by weight of catalyst, 1 part by weight of antioxidant, 1 part by weight of silicone oil and 1 part by weight of water; the following components of component B are as follows: 40 parts by weight of polyisocyanate, 0.005 parts by weight of polymerization inhibitor and 45 parts by weight of polyol; the mass ratio of component A, component B and component C is 100:10:4; the polyol includes 30 parts by weight of polytetramethylene ether glycol with Mn=2000 and 15 parts by weight of high polytetramethylene ether glycol with Mn=1000; the chain extender includes 90 parts by weight of 1,4-butanediol;

[0090] Step 4. Molding and aging: The mixture is injected into a mold, cured and shaped, taken out, and aged to obtain a polyurethane material; the process conditions for curing and molding are: temperature 100°C, time length 30 minutes; the process conditions for aging are: temperature 110°C, time length 6 hours.

[0091] Example 2: A method for preparing a polyurethane material for solid-state battery packaging, comprising the following steps:

[0092] Step 1. Synthesis of prepolymer: Heat polyisocyanate at 72°C until melted, add polymerization inhibitor and mix; slowly add polyol within 30 minutes, then stir at 72°C for 180 minutes at 400 rpm. Stop the reaction when the NCO value reaches 13% to obtain a prepolymer, recorded as component B.

[0093] Step 2. Preparation of a reinforcing agent: The carbon fibers were placed in nitric acid at 100°C for oxidation reaction for 120 minutes; the carbon fibers were then removed, washed several times with distilled water, and dried at 100°C to obtain oxidized carbon fibers; the mass ratio of carbon fibers to nitric acid was 1:15;

[0094] The oxidized carbon fibers were placed in a mixture of thionyl chloride and N,N-dimethylformamide and reacted at 40°C for 240 minutes; after the reaction, excess thionyl chloride was removed to obtain chlorinated carbon fibers; the mass ratio of the oxidized carbon fibers, thionyl chloride and N,N-dimethylformamide mixture was 1:20;

[0095] The chlorinated carbon fibers were placed in a mixture of triethylamine and monoethanolamine in tetrahydrofuran and reacted for 240 minutes. The mixture was then washed with anhydrous ethanol and dried in an oven at 80°C for 2 hours to obtain a modified carbon fiber, i.e., a reinforcing agent, which was designated as component C. The mass ratio of the chlorinated carbon fibers to the mixture of triethylamine and monoethanolamine in tetrahydrofuran was 1:2.7.

[0096] Step 3. Mixing: Disperse the chain extender, the auxiliary agent and water at high speed to obtain component A; mix component A, component B and component C and stir them at high speed to obtain a mixture; the process conditions for high-speed dispersion are: speed 1200 rpm, time 12 minutes; the process conditions for high-speed stirring are: speed 1000 rpm, time 6 minutes; the following components of component A are as follows: 95 parts of chain extender, 1.5 parts of catalyst, 1.5 parts of antioxidant, 2 parts of silicone oil and 2 parts of water, by weight; the following components of component B are as follows: 45 parts of polyisocyanate, 0.005 parts of polymerization inhibitor and 58 parts of polyol, by weight; the mass ratio of component A, component B and component C is 100:12:8; the polyol includes 35 parts of polytetramethylene glycol with Mn=2000 and 23 parts of high polytetramethylene glycol with Mn=1000; the chain extender includes 92 parts of 1,4-butanediol and 3 parts of glycerol;

[0097] Step 4. Molding and aging: The mixture is injected into a mold, cured and shaped, taken out, and aged to obtain a polyurethane material; the process conditions for curing and molding are: temperature 100°C, time length 30 minutes; the process conditions for aging are: temperature 110°C, time length 6 hours.

[0098] Example 3: A method for preparing a polyurethane material for solid-state battery packaging, comprising the following steps:

[0099] Step 1. Synthesis of prepolymer: Heat polyisocyanate at 75°C until melted, add polymerization inhibitor and mix; slowly add polyol within 40 minutes, then stir at 75°C for 180 minutes at 500 rpm. Stop the reaction when the NCO value reaches 13% to obtain a prepolymer, recorded as component B.

[0100] Step 2. Preparation of a reinforcing agent: The carbon fibers were placed in nitric acid at 100°C for oxidation reaction for 18 minutes; the carbon fibers were then removed, washed several times with distilled water, and dried at 100°C to obtain oxidized carbon fibers; the mass ratio of carbon fibers to nitric acid was 1:20;

[0101] The oxidized carbon fibers were placed in a mixture of thionyl chloride and N,N-dimethylformamide and reacted at 40°C for 240 minutes; after the reaction, excess thionyl chloride was removed to obtain chlorinated carbon fibers; the mass ratio of the oxidized carbon fibers, thionyl chloride and N,N-dimethylformamide mixture was 1:25;

[0102] The chlorinated carbon fibers were placed in a mixture of triethylamine and monoethanolamine in tetrahydrofuran and reacted for 240 minutes. The mixture was then washed with anhydrous ethanol and dried in an oven at 80°C for 2 hours to obtain a modified carbon fiber, i.e., a reinforcing agent, which was designated as component C. The mass ratio of the chlorinated carbon fibers to the mixture of triethylamine and monoethanolamine in tetrahydrofuran was 1:3.0.

[0103] Step 3. Mixing: Disperse the chain extender, the auxiliary agent and water at high speed to obtain component A; mix component A, component B and component C and stir them at high speed to obtain a mixture; the process conditions for high-speed dispersion are: speed 1500 rpm, time 10 minutes; the process conditions for high-speed stirring are: speed 1200 rpm, time 5 minutes; the following components of component A are as follows: by weight, 100 parts of chain extender, 2 parts of catalyst, 2 parts of antioxidant, 3 parts of silicone oil and 3 parts of water; the following components of component B are as follows: by weight, 50 parts of polyisocyanate, 0.005 parts of polymerization inhibitor and 70 parts of polyol; the mass ratio of component A, component B and component C is 100:15:12; the polyol includes 40 parts of polytetramethylene glycol with Mn=2000 and 30 parts of high polytetramethylene glycol with Mn=1000; the chain extender includes 95 parts of 1,4-butanediol and 5 parts of glycerol;

[0104] Step 4. Molding and aging: The mixture is injected into a mold, cured and shaped, taken out, and aged to obtain a polyurethane material; the process conditions for curing and molding are: temperature 100°C, time length 30 minutes; the process conditions for aging are: temperature 110°C, time length 6 hours.

[0105] Example 4: A method for preparing a polyurethane material for solid-state battery packaging, comprising the following steps:

[0106] Step 2. Preparation of polyols:

[0107] (1) p-Hydroxybenzaldehyde, epichlorohydrin, and tetrabutylammonium bromide were mixed and refluxed at 70°C for 6 h under a nitrogen atmosphere; after the reaction, the mixture was cooled to room temperature and 1.5 times of a 20 wt% sodium hydroxide aqueous solution was added within 1 h; the mixture was heated to 50°C and refluxed for 6 h; the mixture was cooled to room temperature, the organic layer was diluted with dichloromethane, washed with water, and rotary evaporated to obtain an aldehyde-containing epoxy compound; the mass ratio of p-Hydroxybenzaldehyde, epichlorohydrin, and tetrabutylammonium bromide was 10:7.6:2.5;

[0108] (2) 15 g of aldehyde-containing epoxy compound and diazolidinyl urea were mixed in 100 mL of DMF and THF (the volume ratio of DMF to THF was 1:1) solvent, 0.52 times of triethylamine and 6.9% of tin tetrachloride as a catalyst were added, and the temperature was raised to 25 ° C under nitrogen atmosphere and stirred for 6 hours; after the reaction, the mixture was cooled to room temperature, saturated sodium bicarbonate solution was added, the liquid was separated, and the organic phase was dried with anhydrous magnesium sulfate, filtered, rotary evaporated, and chromatographed to obtain the aldehyde compound; the mass ratio of aldehyde-containing epoxy compound to diazolidinyl urea was 10:11.9;

[0109] (3) 15 g of the aldehyde compound and 100 mL of acetonitrile were mixed, and a fluorine-containing amino compound was added. The mixture was reacted at 60°C for 10 h under a nitrogen atmosphere to form a Schiff base. After the reaction, the mixture was cooled to room temperature, washed, and vacuum-dried to form a Schiff base and obtain a polyhydroxy compound. The fluorine-containing amino compound was 4-(trifluoromethyl)aminocyclohexane. The mass ratio of the aldehyde compound to the fluorine-containing amino compound was 10:3.6.

[0110] Step 3. Prepare the reinforcing agent: Place the chlorinated carbon fiber in a dichloromethane mixture of a catalyst and a polyol and react for 120 minutes. Then, wash it with dilute hydrochloric acid and anhydrous ethanol and dry it in an oven at 80°C for 2 hours to obtain the modified carbon fiber, i.e., the reinforcing agent, recorded as component C. The mass ratio of the catalyst (DCC and DMAP molar ratio is 4:1), the polyol, and the dichloromethane is 0.1:1:3. The mass ratio of the chlorinated carbon fiber and the mixed solution is 1:2.5.

[0111] Step 4. Mixing: The chain extender includes 90 parts of 1,4-butanediol and 5 parts of polyol;

[0112] Step 1 and steps 4-5 are the same as step 1 and steps 3-4 in Example 2 to obtain a polyurethane material.

[0113] Example 5: A method for preparing a polyurethane material for solid-state battery packaging, comprising the following steps:

[0114] Step 2. Preparation of polyols:

[0115] (1) p-Hydroxybenzaldehyde, epichlorohydrin, and tetrabutylammonium bromide were mixed and refluxed at 75°C for 5 h under a nitrogen atmosphere; after the reaction, the mixture was cooled to room temperature and 1.5 times of a 20 wt% sodium hydroxide aqueous solution was added within 1 h; the mixture was heated to 55°C and refluxed for 5 h; the mixture was cooled to room temperature, the organic layer was diluted with dichloromethane, washed with water, and rotary evaporated to obtain an aldehyde-containing epoxy compound; the mass ratio of p-Hydroxybenzaldehyde, epichlorohydrin, and tetrabutylammonium bromide was 10:11.4:2.7;

[0116] (2) 20 g of aldehyde-containing epoxy compound and diazolidinyl urea were mixed in 100 mL of DMF and THF (the volume ratio of DMF to THF was 1:1) solvent, 0.68 times of triethylamine and 8.0% of tin tetrachloride as a catalyst were added, and the temperature was raised to 32 ° C under nitrogen atmosphere and stirred for 5 h; after the reaction, the mixture was cooled to room temperature, saturated sodium bicarbonate solution was added, the liquid was separated, and the organic phase was dried over anhydrous magnesium sulfate, filtered, rotary evaporated, and chromatographed to obtain the aldehyde compound; the mass ratio of aldehyde-containing epoxy compound to diazolidinyl urea was 10:13.8;

[0117] (3) 20 g of the aldehyde compound and 100 mL of acetonitrile were mixed, and a fluorine-containing amino compound was added. The mixture was reacted at 70°C for 8 h under nitrogen atmosphere to form a Schiff base. After the reaction, the mixture was cooled to room temperature, washed, and vacuum-dried to form a Schiff base and obtain a polyhydroxy compound. The fluorine-containing amino compound was 4,4-difluoroaminoethylpiperidine. The mass ratio of the aldehyde compound to the fluorine-containing amino compound was 10:6.5.

[0118] Step 3. Prepare the reinforcing agent: Place the chlorinated carbon fiber in a dichloromethane mixture of a catalyst and a polyol and react for 150 minutes. Then, wash it with dilute hydrochloric acid and anhydrous ethanol and dry it in an oven at 80°C for 2 hours to obtain the modified carbon fiber, i.e., the reinforcing agent, recorded as component C. The mass ratio of the catalyst (DCC and DMAP molar ratio is 4:1), the polyol, and the dichloromethane is 0.15:1:4. The mass ratio of the chlorinated carbon fiber and the mixed solution is 1:2.7.

[0119] Step 4. Mixing: The chain extender includes 90 parts of 1,4-butanediol and 5 parts of polyol;

[0120] Step 1 and steps 4-5 are the same as step 1 and steps 3-4 in Example 2 to obtain a polyurethane material.

[0121] Example 6: A method for preparing a polyurethane material for solid-state battery packaging, comprising the following steps:

[0122] Step 2. Preparation of polyols:

[0123] (1) p-Hydroxybenzaldehyde, epichlorohydrin, and tetrabutylammonium bromide were mixed and refluxed at 80°C for 4 hours under a nitrogen atmosphere; after the reaction, the mixture was cooled to room temperature, and 1.5 times of a 20 wt% sodium hydroxide aqueous solution was added within 1 hour; the mixture was heated to 60°C and refluxed for 4 hours; the mixture was cooled to room temperature, and the organic layer was diluted with dichloromethane, washed with water, and rotary evaporated to obtain an aldehyde-containing epoxy compound; the mass ratio of p-Hydroxybenzaldehyde, epichlorohydrin, and tetrabutylammonium bromide was 10:15.2:3.0;

[0124] (2) 25 g of aldehyde-containing epoxy compound and diazolidinyl urea were mixed in 100 mL of DMF and THF (the volume ratio of DMF to THF was 1:1) solvent, 0.85 times of triethylamine and 9.1% of tin tetrachloride as a catalyst were added, and the temperature was raised to 40 ° C under nitrogen atmosphere and stirred for 4 hours; after the reaction, the mixture was cooled to room temperature, saturated sodium bicarbonate solution was added, the liquid was separated, and the organic phase was dried over anhydrous magnesium sulfate, filtered, rotary evaporated, and chromatographed to obtain the aldehyde compound; the mass ratio of aldehyde-containing epoxy compound to diazolidinyl urea was 10:15.7;

[0125] (3) 25 g of the aldehyde compound and 100 mL of acetonitrile were mixed, and a fluorine-containing amino compound was added. The mixture was reacted at 80°C for 6 h under nitrogen atmosphere to form a Schiff base. After the reaction, the mixture was cooled to room temperature, washed, and vacuum-dried to form a Schiff base and obtain a polyhydroxy compound. The fluorine-containing amino compound was 1,6-diamino-2,2,3,3,4,4,5,5-octafluorohexane. The mass ratio of the aldehyde compound to the fluorine-containing amino compound was 10:9.4.

[0126] Step 3. Prepare the reinforcing agent: Place the chlorinated carbon fiber in a mixture of a catalyst and a polyol in dichloromethane and react for 180 minutes; then wash with dilute hydrochloric acid and anhydrous ethanol and dry in an oven at 80°C for 2 hours to obtain the modified carbon fiber, i.e., the reinforcing agent, recorded as component C; the mass ratio of the catalyst (DCC and DMAP molar ratio is 4:1), the polyol, and dichloromethane is 0.2:1:5. The mass ratio of the chlorinated carbon fiber and the mixed solution is 1:3;

[0127] Step 4. Mixing: The chain extender includes 90 parts of 1,4-butanediol and 5 parts of polyol;

[0128] Step 1 and steps 4-5 are the same as step 1 and steps 3-4 in Example 2 to obtain a polyurethane material.

[0129] Comparative Example 1: A method for preparing a polyurethane material for solid-state battery packaging, comprising the following processes:

[0130] Step 2. Preparation of reinforcing agent: Place the chlorinated carbon fiber in a mixture of catalyst and diazolidinyl urea in dichloromethane and react for 150 minutes; then wash with dilute hydrochloric acid and anhydrous ethanol, and dry in an oven at 80°C for 2 hours to obtain modified carbon fiber, i.e., reinforcing agent, recorded as component C; the mass ratio of catalyst (DCC, DMAP molar ratio is 4:1), diazolidinyl urea, and dichloromethane is 0.15:1:4; the mass ratio of chlorinated carbon fiber and mixed solution is 1:2.7;

[0131] Step 3. Mixing: The chain extender includes 90 parts of 1,4-butanediol and 5 parts of diazolidinyl urea;

[0132] Step 1 and steps 3-4 are the same as those in Example 2 to obtain a polyurethane material.

[0133] Comparative Example 2: A polyurethane material for solid-state battery encapsulation was prepared by replacing the modified carbon fiber with an equal mass of coupled modified carbon fiber as a reinforcement. The other process steps were the same as those in Example 2.

[0134] The preparation process of coupled modified carbon fiber is as follows:

[0135] KH-550 was placed in a mixed solution of ethanol and water (the volume ratio of ethanol to water was 95:5), the pH was adjusted to 4.5 with acetic acid, and stirred for hydrolysis for 30 minutes; the oxidized carbon fiber was immersed in a 3wt% silane solution at 65°C, ultrasonically treated at 200W for 30 minutes, and reacted for 2 hours; after the reaction, it was taken out, washed, and vacuum dried at 80°C for 2 hours.

[0136] Comparative Example 3: A polyurethane material for solid-state battery packaging, in which the modified carbon fiber is replaced with carbon fiber of equal mass as a reinforcement. The other process steps are the same as those in Example 2 to prepare the polyurethane material.

[0137] Experiment: The polyurethane materials obtained in Examples 1-6 and Comparative Examples 1-3 were used to prepare samples, and their properties were tested and the test results were recorded:

[0138] GB / T 531.2-2009 was used as the reference standard to test the hardness (ASKER A) of the specimens. GB / T 528-2009 was used as the reference standard to test the tensile strength (kgf / cm²) and elongation (%) of the specimens. GB / T 529-2008 was used as the reference standard to test the Die-C tear strength (kgf / cm2) of the specimens. ASTM D1056 was used as the reference standard to test the 25% compressive strength (MPa) of the specimens. GB / T 10653 was used as the reference standard to test the permanent compression set (%) of the specimens. GB / T12000 was used as the reference standard to test the change in tensile strength (%) after 500h of damp-heat aging at 85°C / 85%RH. The single-filament pull-out method was used to test the interfacial shear strength (MPa) between the carbon fiber and polyurethane resin in the specimens. ASTM D150 was used as the reference standard to test the dielectric constant (1kHz) of the specimens.

[0139] Table 1. Performance data of Examples 1-3 and Comparative Examples 2-3

[0140]

[0141] Table 2. Performance data of Examples 4-6 and Comparative Example 1

[0142]

[0143] According to the data in the above table, we can clearly draw the following conclusions:

[0144] The polyurethane materials obtained in Examples 1-6 were compared with the polyurethane materials obtained in Comparative Examples 1-3. The test results show that:

[0145] Compared with Comparative Example 3, the polyurethane materials obtained in Examples 1-3 have good hardness, tensile strength, tear strength, compressive strength and compression recovery data, and the tensile strength changes less after wet heat aging, and the interface shear strength and dielectric constant data are better. This fully demonstrates that the present invention achieves improvements in the strength and compression performance of the prepared polyurethane material, and improves its anti-aging performance and electrical properties. The density of the polyurethane material is maintained at 0.8g / cm³. As the amount of modified carbon fiber added increases, the tensile strength, tear strength and compressive strength of the polyurethane material first increase and then decrease, the elongation decreases, and the permanent compression set increases. It can be seen that the optimal addition amount of modified carbon fiber is 4-8%.

[0146] Compared with Example 2, the chain extender in Examples 4-6 contains polyhydroxy compounds, and the surface of the modified carbon fiber is functionalized with polyhydroxy compounds. The tensile strength, tear strength, and compressive strength data of the polyurethane materials prepared in Examples 4-6 increased, the permanent compression deformation rate and the rate of change of tensile strength after wet-heat aging decreased, and the interface shear strength and dielectric constant data improved. Compared with Example 2, the chain extender in Comparative Example 1 contains diazolidinyl urea, and the surface of the modified carbon fiber is functionalized with diazolidinyl urea; the reinforcement in Comparative Example 2 is coupled modified carbon fiber; and the carbon fiber in Comparative Example 3 has not undergone surface modification treatment. The polyurethane materials obtained in Comparative Examples 1-3 have deteriorated in various performance data. It can be seen that the setting of the preparation process and the components used in this application can effectively improve the comprehensive improvement of the strength, compression performance, electrical properties, and wet-heat aging resistance of the prepared polyurethane materials.

[0147] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations that come within the meaning and range of equivalents of the claims be embraced therein.

Claims

1. A method for preparing a polyurethane material for solid-state battery packaging, characterized in that: Including the following processes: Step 1. Synthesis of prepolymer: Heat and melt polyisocyanate, add polymerization inhibitor and polyol, and heat to react to obtain prepolymer, which is recorded as component B; Step 2. Preparing a reinforcing agent: placing the carbon fiber in nitric acid at 100°C and performing an oxidation reaction for 100 to 150 minutes to obtain oxidized carbon fiber; The oxidized carbon fiber is placed in a mixture of thionyl chloride and N,N-dimethylformamide, and reacted at a temperature of 38 to 42° C. for 200 to 280 minutes to obtain chlorinated carbon fiber; The chlorinated carbon fibers are placed in a dichloromethane mixture of a catalyst and a polyhydroxy compound and reacted for 120 to 180 minutes to obtain a modified carbon fiber, i.e., a reinforcing agent, which is recorded as component C; Step 3. Mixing: Disperse the chain extender, additives and water at high speed to obtain component A; mix component A, component B and component C and stir at high speed to obtain a mixture; Step 4. Molding and curing: injecting the mixture into the mold, curing and shaping, taking it out, and curing it to obtain the polyurethane material; The polyol is prepared by the following process: (1) p-Hydroxybenzaldehyde, epichlorohydrin, and tetrabutylammonium bromide are mixed and refluxed at 70-80°C for 4-6 hours under a nitrogen atmosphere; after the reaction, the mixture is cooled to room temperature and an aqueous sodium hydroxide solution is added within 1 hour; the mixture is heated to 50-60°C and refluxed for 4-6 hours to obtain an aldehyde-containing epoxy compound; (2) Mixing an aldehyde-containing epoxy compound and diazolidinyl urea in a solvent, adding triethylamine and a catalyst, heating to 25-40°C under nitrogen atmosphere, stirring and reacting for 4-6 hours to obtain an aldehyde compound; (3) Mixing the aldehyde compound and acetonitrile, adding the fluorine-containing amino compound, and reacting at 60-80°C for 6-10 hours under nitrogen atmosphere to obtain a polyhydroxy compound; In parts by mass, the chain extender includes 90 parts of 1,4-butanediol and 5 parts of the polyhydroxy compound.

2. The method for preparing a polyurethane material for solid-state battery encapsulation according to claim 1, characterized in that: The mass ratio of p-hydroxybenzaldehyde to epichlorohydrin is 10: (7.6-15.2); The mass ratio of the aldehyde-containing epoxy compound to the diazolidinyl urea is 10:(11.9-15.7).

3. The method for preparing a polyurethane material for solid-state battery packaging according to claim 1, characterized in that: The fluorine-containing amino compound is one of 4-(trifluoromethyl)aminocyclohexane, 4,4-difluoroaminoethylpiperidine, 4,4'-[1,4-phenylbis(oxy)]bis[3-(trifluoromethyl)aniline], and 1,6-diamino-2,2,3,3,4,4,5,5-octafluorohexane; The mass ratio of the aldehyde compound to the fluorine-containing amino compound is 10:(3.6-9.4).

4. The method for preparing a polyurethane material for solid-state battery packaging according to claim 1, characterized in that: The polyurethane material includes three components A, B and C; The components of component A are as follows: 90-100 parts by mass of a chain extender, 1-2 parts by mass of a catalyst, 1-2 parts by mass of an antioxidant, 1-3 parts by mass of a silicone oil, and 1-3 parts by mass of water; The B component comprises the following components: 40 to 50 parts by mass of polyisocyanate, 0.005 parts by mass of polymerization inhibitor, and 45 to 70 parts by mass of polyol; The C component is a reinforcing agent; The mass ratio of component A, component B and component C is 100: (10-15): (4-12).

5. The method for preparing a polyurethane material for solid-state battery packaging according to claim 1, characterized in that: The polyisocyanate is 4,4'-diphenylmethane diisocyanate, In parts by mass, the polyol includes 30 to 40 parts of polytetramethylene ether glycol with Mn=2000 and 15 to 30 parts of high polytetramethylene ether glycol with Mn=1000.

6. A polyurethane material for solid-state battery packaging prepared according to the preparation method according to any one of claims 1 to 5.

Images