CN115521750A - Polyurethane-based pouring sealant and preparation method thereof - Google Patents
Polyurethane-based pouring sealant and preparation method thereof Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J175/00—Adhesives based on polyureas or polyurethanes; Adhesives based on derivatives of such polymers
- C09J175/04—Polyurethanes
- C09J175/08—Polyurethanes from polyethers
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- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G18/00—Polymeric products of isocyanates or isothiocyanates
- C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
- C08G18/08—Processes
- C08G18/10—Prepolymer processes involving reaction of isocyanates or isothiocyanates with compounds having active hydrogen in a first reaction step
- C08G18/12—Prepolymer processes involving reaction of isocyanates or isothiocyanates with compounds having active hydrogen in a first reaction step using two or more compounds having active hydrogen in the first polymerisation step
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- C08G18/00—Polymeric products of isocyanates or isothiocyanates
- C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
- C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
- C08G18/40—High-molecular-weight compounds
- C08G18/4009—Two or more macromolecular compounds not provided for in one single group of groups C08G18/42 - C08G18/64
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- C08G18/00—Polymeric products of isocyanates or isothiocyanates
- C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
- C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
- C08G18/40—High-molecular-weight compounds
- C08G18/48—Polyethers
- C08G18/4854—Polyethers containing oxyalkylene groups having four carbon atoms in the alkylene group
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- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G18/00—Polymeric products of isocyanates or isothiocyanates
- C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
- C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
- C08G18/40—High-molecular-weight compounds
- C08G18/64—Macromolecular compounds not provided for by groups C08G18/42 - C08G18/63
- C08G18/6461—Macromolecular compounds not provided for by groups C08G18/42 - C08G18/63 having phosphorus
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- C08G18/00—Polymeric products of isocyanates or isothiocyanates
- C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
- C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
- C08G18/65—Low-molecular-weight compounds having active hydrogen with high-molecular-weight compounds having active hydrogen
- C08G18/66—Compounds of groups C08G18/42, C08G18/48, or C08G18/52
- C08G18/6666—Compounds of group C08G18/48 or C08G18/52
- C08G18/667—Compounds of group C08G18/48 or C08G18/52 with compounds of group C08G18/32 or polyamines of C08G18/38
- C08G18/6674—Compounds of group C08G18/48 or C08G18/52 with compounds of group C08G18/32 or polyamines of C08G18/38 with compounds of group C08G18/3203
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- C08G18/00—Polymeric products of isocyanates or isothiocyanates
- C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
- C08G18/70—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the isocyanates or isothiocyanates used
- C08G18/72—Polyisocyanates or polyisothiocyanates
- C08G18/74—Polyisocyanates or polyisothiocyanates cyclic
- C08G18/76—Polyisocyanates or polyisothiocyanates cyclic aromatic
- C08G18/7657—Polyisocyanates or polyisothiocyanates cyclic aromatic containing two or more aromatic rings
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- C09J11/00—Features of adhesives not provided for in group C09J9/00, e.g. additives
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Abstract
The invention relates to a polyurethane-based pouring sealant and a preparation method thereof, belonging to the technical field of pouring sealants. The pouring sealant comprises the following components in parts by weight: 65-75 parts of polytetrahydrofuran glycol, 32-38 parts of diphenylmethane diisocyanate, 10-15 parts of modified base material, 4-10 parts of heat-conducting filler, 10-20 parts of chain extender, 0.5-2 parts of flatting agent and 1-2 parts of antioxidant; the modified base material is prepared from pentaerythritol and phosphorus oxychloride as raw materials, a phosphorization monomer with a phosphorus-containing diheterocyclic structure is prepared, the cyclohexanol is condensed with-Cl on the phosphorization monomer to form the modified base material, a molecular chain of the modified base material contains a large number of branched phenolic hydroxyl groups, branched polymerization is formed in the copolymerization process, and the phosphorus-containing modified base material is uniformly dispersed in the pouring sealant so as to obtain a uniform flame retardant effect and obtain moderate hardness and good buffering performance.
Description
Technical Field
The invention belongs to the technical field of pouring sealants, and particularly relates to a polyurethane-based pouring sealant and a preparation method thereof.
Background
The pouring sealant is used for bonding, sealing, encapsulating and coating protection of electronic components. The pouring sealant is in a liquid state before being cured, has fluidity, has different glue viscosity according to different materials, performances and production processes of products, and can play roles of water resistance, moisture resistance, dust prevention, insulation, heat conduction, confidentiality, corrosion resistance, temperature resistance and shock resistance after being cured.
The pouring sealant has a plurality of types, and is divided from material types, and the most common main types are 3 types, namely epoxy resin pouring sealant, organic silicon resin pouring sealant and polyurethane pouring sealant; the epoxy resin pouring sealant has good light transmission and low cost, but has high hardness, brittle texture and poor protection on components; the organic silicon resin pouring sealant has good water resistance, moisture resistance and buffering, but the adhesiveness is not good; polyurethane casting glue has good comprehensive performance and is favored.
In order to improve the safety of the polyurethane pouring sealant, in the prior art, a part of liquid flame retardant is doped in the pouring sealant, for example, chinese patent CN101928377A discloses a flame-retardant polyurethane pouring sealant and a preparation method and a use method thereof, 24-39 parts of the liquid flame retardant is added, the liquid flame retardant is difficult to uniformly disperse in the preparation process, segregation is easy to occur after the pouring sealant is cured, and the flame-retardant effect has larger floating in the actual test process; in addition, most of the existing polyurethane base materials for pouring sealant use linear polyurethane glue, the texture is soft, the buffering performance is good, and the impact resistance and the collision damage resistance are relatively reduced.
Disclosure of Invention
In order to solve the technical problems mentioned in the background art, the present invention aims to provide a polyurethane-based potting adhesive and a preparation method thereof.
The purpose of the invention can be realized by the following technical scheme:
a polyurethane-based pouring sealant comprises the following components in parts by weight: 65-75 parts of polytetrahydrofuran glycol, 32-38 parts of diphenylmethane diisocyanate, 10-15 parts of modified base material, 4-10 parts of heat-conducting filler, 10-20 parts of chain extender, 0.5-2 parts of flatting agent and 1-2 parts of antioxidant.
The modified base stock is prepared by the following method:
step A1: adding pentaerythritol and dioxane into a reaction kettle, stirring and dissolving, heating to 65-75 ℃, slowly dropwise adding phosphorus oxychloride, keeping the temperature for 1.25-1.5h after dropwise adding the phosphorus oxychloride, continuously and circularly introducing preheated nitrogen into the reaction kettle in the reaction process, adsorbing at a nitrogen outlet end by using a calcium oxide filter column, introducing chlorine gas from the bottom of the reaction kettle through a guide pipe after reaction, stirring at a high speed, avoiding the influence of a small amount of water mixed in airflow on a product, and performing reduced pressure drying to evaporate a solvent after the chlorine gas is treated, and separating out white crystals to obtain a phosphorization monomer;
the structural formula of the phosphorized monomer is as follows:
further, the molar ratio of the used pentaerythritol to the phosphorus oxychloride is 1:2.08-2.12.
Furthermore, the ventilation capacity of chlorine is 0.1-0.15vvm, the pressure of reduced pressure drying is not more than 45mmHg, and the temperature of reduced pressure drying is 50-60 ℃.
Step A2: adding dimethyl sulfoxide and a small amount of sodium hydroxide solution into a reaction kettle, heating to 110-120 ℃, adding cyclohexanehexol and a phosphorization monomer, and carrying out reflux stirring reaction for 47-52min to obtain the modified base material.
The structural general formula of the modified base stock is as follows:
further, the dosage ratio of the cyclohexanehexol to the phosphorized monomer is 2.85-3.05g:5.15-5.22g.
The heat-conducting filler is prepared by the following method:
step B1: preparing an ethanol solution, heating, adding aluminum nitrate, stirring for dissolving, adding tetraethoxysilane, stirring for mixing, adding aluminum nitride micro powder into the mixed solution in an ultrasonic dispersion state for dispersion, dropwise adding ammonia water into the mixed solution in a stirring state to adjust the pH value of the mixed solution to 8, naturally aging for 12 hours, centrifugally separating out gel, putting the gel into a vacuum sintering furnace, heating to 880-950 ℃, sintering for 2-3 hours, putting the gel into a hydrogen peroxide solution, quenching, filtering out quenching slag, drying, and then crushing at high speed into powder with the diameter not more than 100 meshes to prepare an oxidized material;
and step B2: stirring and mixing the oxidation material and the ethanol solution, adjusting the pH value to 8.7-9.5, soaking for 5h, then placing in an ultrasonic environment, adding KH550 for ultrasonic dispersion for 1h, performing suction filtration, and then placing in a vacuum drying oven for drying to constant weight to obtain the heat-conducting filler.
Further, the using ratio of the aluminum nitrate to the tetraethoxysilane to the aluminum nitride micro powder is 8-11g:30-40g:1-3g.
A preparation method of polyurethane-based pouring sealant comprises the following steps:
step S1: respectively dehydrating polytetrahydrofuran glycol, a modified base material and a chain extender in vacuum, mixing the polytetrahydrofuran glycol and the modified base material according to the weight part ratio, heating to 78-82 ℃ in an oil bath, adding diphenylmethane diisocyanate, keeping the temperature, stirring and reacting for 35-40min to obtain a prepolymer sizing material;
step S2: and sequentially adding a chain extender, a heat-conducting filler, a flatting agent and an antioxidant into the pre-polymerized rubber material, controlling the temperature to be 52-57 ℃, and carrying out heat preservation stirring reaction until the viscosity of a reaction system reaches 620mPa & s to prepare the pouring sealant.
The invention has the beneficial effects that:
1. the invention synthesizes a polyurethane-based pouring sealant by using polytetrahydrofuran diol and diphenylmethane diisocyanate as basic raw materials, introduces modified base material for copolymerization, wherein the modified base material is prepared by taking pentaerythritol and phosphorus oxychloride as raw materials through controlling the dosage and conditions to prepare a phosphorization monomer containing a phosphorus diheterocycle structure, and-Cl groups remain at the end part, and then cyclohexanehexol is condensed with-Cl on the phosphorization monomer to obtain the modified base material of a small-molecular chain polymer, wherein a molecular chain of the modified base material contains a large number of branched phenolic hydroxyl groups, and in the copolymerization process, the diphenylmethane diisocyanate, the polytetrahydrofuran diol and the modified monomer are subjected to branching polymerization, so that the phosphorus-containing modified base material is uniformly dispersed in the pouring sealant to obtain a uniform flame-retardant effect, and in a vertical combustion test, the flame-retardant grade reaches a V-0 grade, and on the other hand, compared with the existing polyurethane material, the branched polymer has moderate hardness and good buffer performance.
2. The invention adopts a sol-gel method to prepare the heat-conducting filler, the aluminum nitride micro powder is uniformly dispersed in the silicon-aluminum gel, and the uniform composite material is prepared by sintering and quenching with hydrogen peroxide solution, has more uniform heat-conducting effect, has higher activity on the surface, is beneficial to coupling treatment and can be uniformly dispersed in the rubber material.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
The polyurethane-based pouring sealant prepared in this example has the following specific implementation process:
1. preparation of modified base stock
a1: taking a reaction kettle provided with a stirrer, a titrator and a conduit, measuring 0.2mol of pentaerythritol and 130mL of dioxane, adding into the reaction kettle, continuously stirring in the process of heating by an oil bath, stirring and dissolving the pentaerythritol, controlling the temperature to be 65 ℃, setting the stirring speed to be 120rpm, measuring 0.416mol of phosphorus oxychloride, using the titrator, setting for 30min, dropwise adding the phosphorus oxychloride into the reaction kettle, carrying out heat preservation reaction for 1.5h after dropwise adding, increasing the rotating speed to be 500rpm after reaction, introducing chlorine from the bottom of the reaction kettle by using the conduit, setting the introduction amount of the chlorine to be 0.1vvm, setting the introduction time to be 10min, then transferring the reaction liquid out, reducing pressure and drying, keeping the pressure not more than 45mmHg, setting the reduced pressure and drying temperature to be 50 ℃, and precipitating white crystals to obtain a phosphorization monomer;
a2: taking a reaction kettle provided with a stirrer and a reflux condenser, adding 600mL of dimethyl sulfoxide and 25mL of sodium hydroxide solution with the mass fraction of 15%, stirring and mixing, heating an oil bath to 110 ℃, measuring 28.5g of cyclohexanehexol and 51.5g of phosphorization monomer, adding into the reaction kettle, setting the stirring speed to be 80rpm, and carrying out reflux stirring reaction for 52min to obtain the modified base material.
2. Preparation of Heat conductive Filler
b1: preparing an ethanol solution with the mass fraction of 20%, heating the ethanol solution to 50 ℃, adding 24g of aluminum nitrate, stirring for dissolving, adding 120g of tetraethoxysilane, stirring and mixing for 3min, adding 9g of aluminum nitride micro powder (provided by a certain powder material company, shanghai, and the like, and the D90 is less than or equal to 3 microns) into the mixed solution in a 28kHz ultrasonic dispersion state, stirring after dispersing the aluminum nitride micro powder, dropwise adding ammonia water until the pH value of the mixed solution is 8, naturally aging for 12h, centrifugally separating out gel, putting the gel into a vacuum sintering furnace, heating to 880 ℃, sintering for 3h, discharging the gel after sintering to a hydrogen peroxide solution with the mass fraction of 2%, quenching, filtering, putting the quenched slag into a hot air drying box, drying to the constant weight, then transferring the slag into a high-speed pulverizer, and pulverizing until all the pulverized materials pass through a 100-mesh screen to prepare an oxidized material;
b2: stirring and mixing the oxidation material and 20% ethanol solution by mass, adjusting the pH value to 8.7 by using sodium hydroxide, soaking for 5h, then placing in an ultrasonic dispersion instrument, adding 50mLKH550 for ultrasonic dispersion for 1h, carrying out suction filtration, taking a filtrate, placing in a vacuum drying oven, and drying to constant weight to obtain the heat-conducting filler.
3. Preparation of the potting adhesive
s1: putting polytetrahydrofuran diol, a modified base material and a chain extender (1,4-butanediol is selected in the embodiment) into a vacuum dehydrator respectively, dehydrating for 30min at the set temperature of 90 ℃, then metering 65g of dehydrated polytetrahydrofuran diol and 15g of modified base material, adding into a reactor for mixing, heating in an oil bath until the temperature of a reaction system reaches 78 ℃, adding 32g of diphenylmethane diisocyanate into the reactor, keeping the temperature, stirring and reacting for 40min to obtain a prepolymer sizing material;
s2: adding 20g of chain extender, 4g of heat-conducting filler, 0.5g of flatting agent (BYK-054 is selected in the embodiment) and 1g of antioxidant (antioxidant 1010 is selected in the embodiment) into the pre-polymerized rubber material, controlling the temperature to be 52 ℃, and carrying out heat preservation stirring reaction until the viscosity of the reaction system reaches 620mPa & s to prepare the pouring sealant.
Example 2
The polyurethane-based pouring sealant prepared in the embodiment is specifically implemented as follows:
1. preparation of modified base stock
a1: taking a reaction kettle provided with a stirrer, a titrator and a conduit, measuring 0.2mol of pentaerythritol and 150mL of dioxane, adding into the reaction kettle, continuously stirring in the process of heating by an oil bath, stirring and dissolving the pentaerythritol, controlling the temperature to be 70 ℃, setting the stirring speed to be 120rpm, measuring 0.42mol of phosphorus oxychloride, using the titrator, setting for 30min, dropwise adding the phosphorus oxychloride into the reaction kettle, carrying out heat preservation reaction for 1.37h after dropwise adding, increasing the rotating speed to be 500rpm after reaction, introducing chlorine from the bottom of the reaction kettle by using the conduit, setting the introduction amount of the chlorine to be 0.12vvm, setting the introduction time to be 10min, then transferring the reaction liquid out, reducing pressure and drying, keeping the pressure not more than 45mmHg, setting the reduced pressure and drying temperature to be 60 ℃, and precipitating white crystals to obtain a phosphorization monomer;
a2: taking a reaction kettle provided with a stirrer and a reflux condenser, adding 600mL of dimethyl sulfoxide and 25mL of sodium hydroxide solution with the mass fraction of 15%, stirring and mixing, heating an oil bath to 120 ℃, measuring 29g of cyclohexanehexol and 52g of phosphorization monomer, adding into the reaction kettle, setting the stirring speed to 80rpm, and carrying out reflux stirring reaction for 50min to obtain the modified base material.
2. Preparation of Heat conductive Filler
b1: preparing an ethanol solution with the mass fraction of 20%, heating the ethanol solution to 50 ℃, adding 28g of aluminum nitrate, stirring and dissolving, adding 110g of ethyl orthosilicate, stirring and mixing for 3min, adding 6g of aluminum nitride micro powder (provided by Shanghai certain powder material Co., ltd., D90 is less than or equal to 3 mu m) into the mixed solution under the condition of 28kHz ultrasonic dispersion, transferring out and stirring after the aluminum nitride micro powder is dispersed, dropwise adding ammonia water until the pH value of the mixed solution is 8, naturally aging for 12h, centrifugally separating out gel, putting the gel into a vacuum sintering furnace, heating to 920 ℃, sintering for 2.5h, discharging the gel after sintering into a hydrogen peroxide solution with the mass fraction of 2%, quenching, filtering, putting the quenched slag into a hot air drying box, drying to constant weight, then transferring into a high-speed pulverizer, pulverizing until all pulverized materials pass through a 100-mesh screen, and preparing an oxidized material;
b2: stirring and mixing the oxidation material and 20% ethanol solution by mass fraction, adjusting the pH value to 9 with sodium hydroxide, soaking for 5h, then placing in an ultrasonic dispersion instrument, adding 55mLKH550 for ultrasonic dispersion for 1h, performing suction filtration, taking the filtrate, placing in a vacuum drying oven, and drying to constant weight to obtain the heat-conducting filler.
3. Preparation of the pouring sealant
s1: putting polytetrahydrofuran diol, a modified base material and a chain extender (1,4-butanediol is selected in the embodiment) into a vacuum dehydrator respectively, dehydrating for 30min at the set temperature of 90 ℃, then metering 70g of dehydrated polytetrahydrofuran diol and 12g of modified base material, adding into a reactor for mixing, heating in an oil bath until the temperature of a reaction system reaches 80 ℃, adding 35g of diphenylmethane diisocyanate into the reactor, keeping the temperature, stirring and reacting for 38min to obtain a prepolymer sizing material;
s2: adding 15g of chain extender, 8g of heat-conducting filler, 1g of flatting agent (BYK-054 is selected in the embodiment) and 1g of antioxidant (antioxidant 1010 is selected in the embodiment) into the pre-polymerized sizing material, controlling the temperature to be 55 ℃, keeping the temperature, stirring and reacting until the viscosity of the reaction system reaches 620mPa & s, and preparing the pouring sealant.
Example 3
The polyurethane-based pouring sealant prepared in the embodiment is specifically implemented as follows:
1. preparation of modified base stock
a1: taking a reaction kettle provided with a stirrer, a titrator and a conduit, measuring 0.2mol of pentaerythritol and 160mL of dioxane, adding into the reaction kettle, continuously stirring in the process of heating by an oil bath, stirring and dissolving the pentaerythritol, controlling the temperature to be 75 ℃, setting the stirring speed to be 120rpm, measuring 0.424mol of phosphorus oxychloride, using the titrator, setting for 30min, dropwise adding the phosphorus oxychloride into the reaction kettle, carrying out heat preservation reaction for 1.25h after dropwise adding, increasing the rotating speed to be 500rpm after reaction, introducing chlorine from the bottom of the reaction kettle by using the conduit, setting the introduction amount of the chlorine to be 0.15vvm, setting the introduction time to be 13min, then transferring the reaction liquid out, reducing pressure and drying, keeping the pressure not more than 45mmHg, setting the reduced pressure and drying temperature to be 60 ℃, and precipitating white crystals to obtain a phosphorization monomer;
a2: taking a reaction kettle provided with a stirrer and a reflux condenser, adding 600mL of dimethyl sulfoxide and 25mL of 15 mass percent sodium hydroxide solution, stirring and mixing, heating an oil bath to 120 ℃, metering 30.5g of cyclohexanehexol and 52.2g of phosphorization monomers, adding into the reaction kettle, setting the stirring speed to be 80rpm, and carrying out reflux stirring reaction for 47min to obtain the modified base material.
2. Preparation of Heat conductive Filler
b1: preparing an ethanol solution with the mass fraction of 20%, heating the ethanol solution to 50 ℃, adding 33g of aluminum nitrate, stirring and dissolving, adding 90g of ethyl orthosilicate, stirring and mixing for 3min, adding 3g of aluminum nitride micro powder (provided by Shanghai certain powder material Co., ltd., D90 is less than or equal to 3 mu m) into the mixed solution under the condition of 28kHz ultrasonic dispersion, stirring after the aluminum nitride micro powder is dispersed, dropwise adding ammonia water until the pH value of the mixed solution is 8, naturally aging for 12h, centrifugally separating out gel, putting the gel into a vacuum sintering furnace, heating to 950 ℃, sintering for 2h, discharging the gel after sintering to a hydrogen peroxide solution with the mass fraction of 2%, quenching, filtering, putting the quenched slag into a hot air drying box, drying to constant weight, then transferring into a high-speed pulverizer, and pulverizing until all pulverized materials pass through a 100-mesh screen to prepare an oxidized material;
b2: stirring and mixing the oxidation material and 20% ethanol solution by mass fraction, adjusting the pH value to 9.5 by using sodium hydroxide, soaking for 5 hours, then placing the mixture into an ultrasonic dispersion instrument, adding 50mLKH550 for ultrasonic dispersion for 1 hour, carrying out suction filtration, taking the filtrate, placing the filtrate into a vacuum drying oven, and drying until the weight is constant to obtain the heat-conducting filler.
3. Preparation of the potting adhesive
s1: putting polytetrahydrofuran glycol, a modified base material and a chain extender (1,4-butanediol is selected in the embodiment) into a vacuum dehydrator respectively, dehydrating for 30min at the set temperature of 90 ℃, metering 75g of dehydrated polytetrahydrofuran glycol and 10g of modified base material, adding into a reactor for mixing, heating in an oil bath until the temperature of a reaction system reaches 82 ℃, adding 38g of diphenylmethane diisocyanate into the reactor, keeping the temperature, stirring and reacting for 35min to obtain a prepolymer sizing material;
s2: adding 10g of chain extender, 10g of heat-conducting filler, 2g of flatting agent (BYK-054 is selected in the embodiment) and 2g of antioxidant (antioxidant 1010 is selected in the embodiment) into the pre-polymerized rubber material, controlling the temperature to be 57 ℃, and carrying out heat preservation stirring reaction until the viscosity of the reaction system reaches 620mPa & s to prepare the pouring sealant.
The pouring sealant prepared in the embodiments 1 to 3 is used for performance test, and the specific test results are as follows:
TABLE 1
As can be seen from the data in Table 1, the pouring sealant prepared by the invention is semitransparent jelly, has the viscosity of 625-633 mPa.s, and is convenient to encapsulate; the hardness after curing is 68-76A, the buffer coefficient is 7.26-7.82, and the protective effect is good; volume resistivity of 9.22-10.02 x 10 13 Omega · m, thermal conductivity of 0.6182-0.6724W/m · K, and good insulation and heat dissipation performance.
In the description herein, references to the description of "one embodiment," "an example," "a specific example" or the like are intended to mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
The foregoing is illustrative and explanatory only and is not intended to be exhaustive or to limit the invention to the precise embodiments described, and various modifications, additions, and substitutions may be made by those skilled in the art without departing from the scope of the invention or exceeding the scope of the claims.
Claims (7)
1. A polyurethane-based pouring sealant comprises 65-75 parts of polytetrahydrofuran diol, 32-38 parts of diphenylmethane diisocyanate, 10-20 parts of chain extender, 0.5-2 parts of flatting agent and 1-2 parts of antioxidant, and is characterized in that 10-15 parts of modified base material and 4-10 parts of copolymerization and heat-conducting filler are added into the pouring sealant for blending;
the modified base stock is prepared by the following method:
step A1: dissolving pentaerythritol with dioxane, heating to 65-75 ℃, dropwise adding phosphorus oxychloride, reacting for 1.25-1.5h while keeping the temperature, introducing chlorine gas under stirring after the reaction, and finally drying under reduced pressure to obtain a phosphorization monomer;
step A2: mixing dimethyl sulfoxide and sodium hydroxide solution, heating to 110-120 deg.C, adding cyclohexanehexol and phosphorized monomer, refluxing, stirring, and reacting for 47-52min to obtain modified base material.
2. The polyurethane-based pouring sealant as claimed in claim 1, wherein the molar ratio of the pentaerythritol to the phosphorus oxychloride is 1:2.08-2.12.
3. The polyurethane-based potting adhesive of claim 1, wherein the amount of chlorine gas ventilated is 0.1 to 0.15vvm, the pressure for reduced pressure drying is not more than 45mmHg, and the temperature for reduced pressure drying is 50 to 60 ℃.
4. The polyurethane-based pouring sealant as claimed in claim 1, wherein the ratio of the amount of the cyclohexanehexol to the amount of the phosphatized monomer is 2.85-3.05g:5.15-5.22g.
5. The polyurethane-based pouring sealant as claimed in claim 1, wherein the heat conductive filler is prepared by the following steps:
step B1: dissolving an ethanol solution and aluminum nitrate, adding tetraethoxysilane for mixing, then adding aluminum nitride micro powder in an ultrasonic dispersion state, adding ammonia water for adjusting the pH value of the mixed solution to 8, naturally aging for 12 hours, centrifugally separating out gel, sintering the gel in vacuum at 880-950 ℃ for 2-3 hours, then quenching the gel in a hydrogen peroxide solution, filtering out quenching slag, and crushing the quenching slag into powder with the particle size not exceeding 100 meshes to prepare an oxidation material;
and step B2: mixing the oxide with ethanol solution, adjusting pH to 8.7-9.5, soaking for 5h, placing in ultrasonic environment, adding KH550, ultrasonically dispersing for 1h, vacuum-filtering, and vacuum drying to constant weight to obtain the heat-conducting filler.
6. The polyurethane-based pouring sealant as claimed in claim 5, wherein the ratio of the aluminum nitrate to the tetraethoxysilane to the aluminum nitride micropowder is 8-11g:30-40g:1-3g.
7. The preparation method of the polyurethane-based pouring sealant as claimed in claim 1, comprising the steps of:
step S1: respectively dehydrating polytetrahydrofuran glycol, a modified base material and a chain extender in vacuum, then mixing the polytetrahydrofuran glycol and the modified base material according to the weight part ratio, heating in an oil bath to 78-82 ℃, adding diphenylmethane diisocyanate, keeping the temperature, stirring and reacting for 35-40min to obtain a prepolymerization material;
step S2: and sequentially adding a chain extender, a heat-conducting filler, a flatting agent and an antioxidant into the pre-polymerized rubber material, controlling the temperature to be 52-57 ℃, and carrying out heat preservation stirring reaction until the viscosity of a reaction system reaches 620mPa & s to prepare the pouring sealant.
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| JP2008013629A (en) * | 2006-07-04 | 2008-01-24 | Sk Kaken Co Ltd | Foaming fireproof coating |
| CN103524698A (en) * | 2013-08-27 | 2014-01-22 | 福建瑞森化工有限公司 | Halogen-free flame retardant heat conduction polyurethane pouring sealant and preparation method thereof |
| CN104900793A (en) * | 2015-06-02 | 2015-09-09 | 华东师范大学 | Preparation and application of insulating core shell composite structure high in heat conduction and high in reflectivity |
| CN105085575A (en) * | 2015-09-05 | 2015-11-25 | 四川大学 | Flame-retardant polyol containing phosphorus linked pendant groups and preparation method of polyol |
| CN107142016A (en) * | 2017-06-29 | 2017-09-08 | 铜陵市永创变压器电子有限公司 | A kind of transformer class montmorillonite filled heat conductive insulating paint of aluminium nitride and preparation method thereof |
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008013629A (en) * | 2006-07-04 | 2008-01-24 | Sk Kaken Co Ltd | Foaming fireproof coating |
| CN103524698A (en) * | 2013-08-27 | 2014-01-22 | 福建瑞森化工有限公司 | Halogen-free flame retardant heat conduction polyurethane pouring sealant and preparation method thereof |
| CN104900793A (en) * | 2015-06-02 | 2015-09-09 | 华东师范大学 | Preparation and application of insulating core shell composite structure high in heat conduction and high in reflectivity |
| CN105085575A (en) * | 2015-09-05 | 2015-11-25 | 四川大学 | Flame-retardant polyol containing phosphorus linked pendant groups and preparation method of polyol |
| CN107142016A (en) * | 2017-06-29 | 2017-09-08 | 铜陵市永创变压器电子有限公司 | A kind of transformer class montmorillonite filled heat conductive insulating paint of aluminium nitride and preparation method thereof |
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