CN112358647A - High-strength polyurethane rigid foam plastic and preparation method thereof - Google Patents
High-strength polyurethane rigid foam plastic and preparation method thereof Download PDFInfo
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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
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- 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
- C08G18/4804—Two or more polyethers of different physical or chemical nature
- C08G18/482—Mixtures of polyethers containing at least one polyether containing nitrogen
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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
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- C08J2375/00—Characterised by the use of polyureas or polyurethanes; Derivatives of such polymers
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- C08J2375/08—Polyurethanes from polyethers
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- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/32—Phosphorus-containing compounds
- C08K2003/321—Phosphates
- C08K2003/322—Ammonium phosphate
- C08K2003/323—Ammonium polyphosphate
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- C08K2201/00—Specific properties of additives
- C08K2201/011—Nanostructured additives
Abstract
The invention discloses a high-strength polyurethane rigid foam plastic and a preparation method thereof. Firstly, grafting metal hydroxide on a carbon nano tube to obtain a filler, introducing ammonium polyphosphate into the filler to form a material C, generating sulfonic groups on the surface of expanded graphite through ozone, compounding the material C with the expanded graphite with the sulfonic groups on the surface, and introducing a macromolecular long chain to the surface of the material C to enable the material C to be entangled with the macromolecular long chain in the polyurethane rigid foam plastic, so that a stable network structure is formed in the polyurethane rigid foam plastic, and the mechanical property of the polyurethane rigid foam plastic is further improved; the polyurethane rigid foam plastic prepared by utilizing the synergistic effects of the components has excellent flame retardant effect, strong mechanical property, good waterproof effect, difficult aging and high practical value.
Description
Technical Field
The invention relates to the technical field of rigid foam plastics, in particular to high-strength polyurethane rigid foam plastic and a preparation method thereof.
Background
The rigid polyurethane foam is mainly prepared by polymerizing and foaming isocyanate and hydroxyl compound, and can be divided into flexible rigid polyurethane foam and rigid polyurethane foam according to the hardness. The soft foam plastic has excellent performances of good elasticity, flexibility, chemical stability, heat insulation and the like, and can be used as a buffer material; the polyurethane rigid foam plastic is widely used in the fields of refrigerators, solar energy, buildings and the like, and has an excellent buffering effect.
With the improvement of living standard, people put higher requirements on the service performance of polyurethane rigid foam plastics used in the fields of buildings, pipelines, containers and the like; the polyurethane rigid foam plastics on the market at present have the problems of high brittleness and low strength, insufficient mechanical property, easy breakage and the like caused by impact, and can not meet the requirements of people;
the main component of the polyurethane rigid foam plastic is C, H element, which is easy to burn without flame retardant element, once touching flame, it will burn immediately, which will threaten the personal safety, economy and property of people; in order to improve the flame retardancy of the rigid polyurethane foam, a flame retardant is usually added to the rigid polyurethane foam; ammonium polyphosphate can be decomposed to form acidic substances and gases such as phosphoric acid, polyphosphoric acid, metaphosphoric acid and the like in a hot state, and has good flame retardant and smoke suppression effects; when the expanded graphite meets high temperature, the volume of the expanded graphite can instantaneously expand by 150-300 times, and the structure is changed into a worm shape from a sheet shape to cover the surface of the material, so that the further combustion of the material is prevented; ammonium polyphosphate and expanded graphite have good flame retardance and are safe and environment-friendly, so that the ammonium polyphosphate and the expanded graphite are often used as flame retardants to be directly added into the rigid polyurethane foam plastics, but the ammonium polyphosphate and the expanded graphite have poor compatibility with the rigid polyurethane foam plastics, and the direct addition of the ammonium polyphosphate and the expanded graphite affects the foaming performance of the rigid polyurethane foam plastics, so that the problems of reduced stability of the rigid polyurethane foam plastics, reduced mechanical properties of the rigid polyurethane foam plastics and the like are caused;
polyurethane rigid foam plastic serving as a high polymer material which can be used in various industrial fields in life has requirements on flame retardance and mechanical properties, and in order to meet market demands, the polyurethane rigid foam plastic which has a good flame retardant effect and high strength and a preparation method thereof are urgently needed to be developed.
Disclosure of Invention
The present invention aims to provide a high strength rigid polyurethane foam and a preparation method thereof, so as to solve the problems in the background art.
In order to solve the technical problems, the invention provides the following technical scheme: a high-strength polyurethane rigid foam plastic and a preparation method thereof.
The high-strength rigid polyurethane foam plastic comprises the following raw material components: by weight, 100-150 parts of toluenediamine polyether polyol, 15-25 parts of foaming agent, 15-25 parts of foam stabilizer, 150-250 parts of polyurethane prepolymer, 15-25 parts of catalyst, 20-30 parts of filler, 30-50 parts of graphite powder, 20-30 parts of sulfuric acid, 25-35 parts of 1-allyl-3-methylimidazole chloride, 30-60 parts of ammonium polyphosphate, 20-40 parts of silane coupling agent, 25-35 parts of N, N-dimethylformamide and 60-70 parts of coating liquid.
Further, the foaming agent is one or more of methyl formate, HFC-245fa and HFC-365 mfa; the foam stabilizer is low-thermal conductivity silicone oil L-6900; the catalyst is one or more of ethyl acetate and pentamethyldiethylenetriamine; the silane coupling agent is one of KH550, KH560 and KH 570.
Firstly, grafting layered Mg-Al metal hydroxide on a carbon nano tube by an electric auxiliary method to generate a hydrotalcite-structured filler with high adsorption performance; then, the flame retardant property of the ammonium polyphosphate is further enhanced through the reaction of the ammonium polyphosphate and a silane coupling agent; the positive ions on the silane coupling agent and the negative ions on the filler are subjected to charge reaction, and the ammonium polyphosphate is adsorbed into the filler to form a material C under the drive of the positive ions in the silane coupling agent; at the same time, the anions on the filler are consumed, and the resulting material C is positively charged.
The method comprises the steps of treating graphite powder with sulfuric acid to enable the graphite powder to be changed into expanded graphite, namely material D, mixing the material D with material C, tolylenediamine polyether polyol and deionized water, introducing ozone while stirring for reaction, and introducing negatively charged sulfonic groups on the surface of the expanded graphite by adding the ozone; the material C and the expanded graphite with sulfonic groups on the surface are compounded together by charge interaction to form a material C/expanded graphite compound; 1-allyl-3-methylimidazole chloride salt is decomposed in toluenediamine polyether polyol and deionized water to form ions with imidazole and vinyl structures, and the ions with the imidazole and vinyl structures are introduced to the surface of the material C/expanded graphite compound through electrostatic self-assembly reaction due to the fact that the expanded graphite has negative charges; the addition of N, N-dimethyl formamide can make the ethylene group on the surface of the material C/expanded graphite compound quickly polymerize to form an organic coating containing a macromolecular long chain, the macromolecular long chain in the coating is highly entangled with the macromolecular chain in the polyurethane rigid foam plastic, the compatibility of the material C/expanded graphite compound in the polyurethane rigid foam plastic is increased, and the mechanical property of the polyurethane rigid foam plastic is improved.
Further, the coating liquid mainly comprises glutamic acid, alanine and pentanediol, and the mass ratio of the glutamic acid to the alanine to the pentanediol is (7-9): 3: 1.
the glutamic acid, the alanine and the pentanediol which are specially added in the invention are crosslinked to form a compact waterproof layer on the polyurethane rigid foam plastic, so that the hydrophobicity of the surface of the polyurethane rigid foam plastic is enhanced, and the aging is prevented.
Furthermore, the toluene diamine polyether polyol is prepared by the addition reaction of toluene diamine serving as an initiator with propylene oxide and ethylene oxide; the hydroxyl value of the toluene diamine polyether polyol is 370-400mgKOH/g, and the viscosity is 8500-9500mpa.
A preparation method of high-strength polyurethane rigid foam plastic comprises the following steps:
s1 preparation of polyurethane prepolymer: mixing polymeric isocyanate and polymethyl propylene glycol, and stirring for reaction under a high-pressure condition to obtain a polyurethane prepolymer;
s2 preparation of a filler:
s3 synthesizing a high-strength polyurethane rigid foam plastic preparation:
A. placing ammonium polyphosphate into ethanol, stirring and dissolving, and adding a silane coupling agent to obtain a solution A;
B. placing the filler into the solution A, stirring, pouring the filler into a polyurethane prepolymer after stirring, and stirring for reaction to obtain a material C;
C. putting graphite powder into sulfuric acid, stirring, and performing suction filtration and drying to obtain a material D;
D. mixing the material C, the material D, the toluenediamine polyether polyol and deionized water, adding 1-allyl-3-methylimidazole chloride and N, N-dimethylformamide while stirring in a nitrogen atmosphere, and continuously stirring for reaction to obtain a material E;
E. adding a foaming agent, a foam stabilizer and a catalyst into the material E in sequence, stirring, standing, injecting into a mold, curing, then opening the mold, and standing at room temperature to obtain a polyurethane rigid foam plastic preparation;
s4 preparation of high-hardness polyurethane rigid foam:
A. preparing a coating solution: uniformly stirring acetone, glutamic acid, alanine and pentanediol water solution to obtain coating liquid;
B. and quickly soaking the polyurethane rigid foam plastic preparation body in the coating liquid, taking out and drying to obtain the high-strength polyurethane foam plastic.
The method specifically comprises the following steps:
s1 preparation of polyurethane prepolymer: mixing polymeric isocyanate and polymethyl propylene glycol, and stirring and reacting for 4-7h under a high-pressure condition to obtain a polyurethane prepolymer; the polymeric isocyanate is one of polymethylene polyphenyl polyisocyanate, diphenylmethane diisocyanate and isophorone diisocyanate, and the polymethylene polyphenyl polyisocyanate is preferably selected in the scheme.
S2 preparation of a filler:
s3 synthesizing a high-strength polyurethane rigid foam plastic preparation:
A. placing ammonium polyphosphate into ethanol, stirring and dissolving, adding a silane coupling agent at 35-45 ℃, and stirring and reacting for 2-3h to obtain a solution A;
B. placing the filler into the solution A, stirring for 3-10min, pouring the filler into the polyurethane prepolymer at the speed of 30-50ml/min after stirring, and stirring to react for 1-2h under the reaction condition of 70-90 ℃ to obtain a material C;
C. placing graphite powder in sulfuric acid, stirring to react for 35-65min, and performing suction filtration and drying to obtain a material D; the invention uses sulfuric acid to carry out intercalation treatment on graphite powder to generate expanded graphite;
D. mixing the material C, the material D, the toluenediamine polyether polyol and deionized water, stirring and reacting for 15-20min at the rotating speed of 700r/min in the nitrogen atmosphere, adding the 1-allyl-3-methylimidazole chlorine salt and the N, N-dimethylformamide while stirring, and continuously stirring and reacting for 1-2h to obtain a material E; the method of adding 1-allyl-3-methylimidazole chloride and N, N-dimethylformamide while stirring can ensure that the 1-allyl-3-methylimidazole chloride and the N, N-dimethylformamide react with the material C, the material D and the toluenediamine polyether polyol more timely and fully, the generated material E component is more uniform, and the network structure effect is better and more stable.
E. Adding a foaming agent, a foam stabilizer and a catalyst into the material E in sequence, stirring for 10-20min, standing for 1-2h, injecting into a mold, curing, then opening the mold, and standing at room temperature for 18-24h to obtain a rigid polyurethane foam plastic preparation;
s4 preparation of high-hardness polyurethane rigid foam:
A. preparing a coating solution: uniformly stirring acetone, glutamic acid, alanine and pentanediol water solution to obtain coating liquid;
B. heating the coating liquid to 30-40 ℃ and keeping the temperature constant, quickly soaking the polyurethane rigid foam plastic preparation body into the coating liquid, reacting for 2-3h in a low-pressure environment, taking out and drying for 2-4h to obtain high-strength polyurethane foam plastic; under the heating environment, the movement of the coating liquid molecules in the polyurethane rigid foam plastic is accelerated, the reaction time is shortened, and the reaction process is more sufficient.
Further, the step D of the step S3 needs to be added with ozone while stirring, and the ozone discharge amount is 20-60L/min; the ozone reacts with the expanded graphite to generate sulfonic groups with negative charges on the surface of the expanded graphite; sulfonic groups are directly introduced on the surface of the expanded graphite through ozone, so that adverse effects on the performance of the polyurethane rigid foam plastic caused by the addition of excessive components are avoided; and in the step S4, the pressure of the low-pressure environment is 0.4-0.6atm, and air in the polyurethane rigid foam plastic is extruded under the low-pressure condition, so that the coating liquid can be fully extruded into pores of the polyurethane rigid foam plastic under the action of pressure and is subjected to cross-linking polymerization on the surface of the coating liquid to form a compact waterproof coating, and the aging of the polyurethane rigid foam plastic caused by the adsorption of water in the air by hydrophilic functional groups in the polyurethane rigid foam plastic is avoided.
Further, the preparation method of the filler comprises the following steps: (1) soaking the carbon nano tube in the first electrolyte for 20-40min, putting an aluminum bar electrode, electrifying for 15-35min, taking out, drying, and pyrolyzing for 35-45min to obtain a material A; (2) soaking the material A in a second electrolyte for 20-40min, placing an iron rod electrode, electrifying for 15-35min, adjusting pH to 7-9, and drying to obtain a material B; (3) uniformly mixing the material B and ethanol, and performing ball milling for 35-55min to obtain a filler; the particle size of the filler is further refined through ball milling, the smaller the particle size of the filler is, the stronger the foam stability of the polyurethane rigid foam plastic is, and the better the mechanical property of the generated polyurethane rigid foam plastic is.
Further, the first electrolyte in the step (1) is sodium chloride; introducing aluminum ions and hydroxyl ions into the carbon nano tube, and further reacting the aluminum ions and the hydroxyl ions to generate aluminum hydroxide on the carbon nano tube; and (3) introducing magnesium hydroxide into the carbon nano tube by the same principle, wherein the second electrolyte in the step (2) is magnesium chloride.
Further, the pyrolysis temperature in the step (2) is 550-750 ℃.
Furthermore, the preparation method of the filler is carried out in a nitrogen atmosphere in the whole process, so that the influence of other components in the air on reaction products is avoided.
Compared with the prior art, the invention has the following beneficial effects:
the single nano particle can increase the strength of the plastic, but can not increase the flame retardant property of the plastic at the same time, and the filler is obtained by grafting Mg-Al metal hydroxide on the carbon nano tube, so that on one hand, the Mg-Al metal hydroxide can enhance the strength of the carbon nano tube and optimize the mechanical property of the carbon nano tube, thereby indirectly enhancing the mechanical strength of the polyurethane rigid foam plastic; on the other hand, ammonium polyphosphate is introduced into the filler to form a material C, the material C and the expanded graphite with sulfonic groups on the surface are subjected to charge interaction and are compounded together to form a material C/expanded graphite compound, and the compound can provide more active sites for the growth of polyurethane foam and assist in improving the stability of the foam; the macromolecule long chain is introduced to the surface of the material C/expanded graphite compound, so that the material C/expanded graphite compound is entangled with the macromolecule long chain in the polyurethane rigid foam plastic to form a stable network structure, and the mechanical property of the polyurethane rigid foam plastic and the compatibility of the material C/expanded graphite compound in the polyurethane rigid foam plastic are further improved.
According to the invention, ammonium polyphosphate is enclosed in the filler, and when the ammonium polyphosphate is decomposed by heating, the layered structure of the filler on the surface of the ammonium polyphosphate can hinder the exchange of heat and pyrolysis products between flame and a high polymer material, so that the flame retardance of the rigid polyurethane foam plastic is improved; meanwhile, the ammonium polyphosphate wrapped by the filler cannot directly react with the rigid polyurethane foam plastic, and has small influence on the mechanical property and the foam stability of the rigid polyurethane foam plastic.
The polyurethane rigid foam plastic prepared by utilizing the synergistic effects of the components has excellent flame retardant effect, strong mechanical property, good waterproof effect, difficult aging and high practical value.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all 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 high-strength rigid polyurethane foam plastic comprises the following raw material components: the coating comprises, by weight, 100 parts of toluenediamine polyether polyol, 15 parts of a foaming agent, 15 parts of a foam stabilizer, 150 parts of a polyurethane prepolymer, 15 parts of a catalyst, 20 parts of a filler, 30 parts of graphite powder, 20 parts of sulfuric acid, 25 parts of 1-allyl-3-methylimidazole chloride, 30 parts of ammonium polyphosphate, 20 parts of a silane coupling agent, 25 parts of N, N-dimethylformamide and 60 parts of a coating liquid.
The mass ratio of glutamic acid, alanine and pentanediol in the coating liquid is 7: 3: 1; the hydroxyl value of the toluene diamine polyether polyol is 370mgKOH/g, and the viscosity is 8500 mpa.s.
S1 preparation of polyurethane prepolymer: mixing polymethylene polyphenyl polyisocyanate and polymethylpropylene glycol, and stirring and reacting for 4 hours under a high-pressure condition to obtain a polyurethane prepolymer;
s2 preparation of a filler:
A. soaking the carbon nano tube in the first electrolyte for 20min, putting an aluminum bar electrode, electrifying for 15min, taking out, drying, and pyrolyzing at 550 ℃ for 35min to obtain a material A;
B. soaking the material A in a second electrolyte for 20min, placing an iron rod electrode, electrifying for 15min, adjusting the pH value to 7, and drying to obtain a material B;
C. uniformly mixing the material B and ethanol, and performing ball milling for 35min to obtain a filler;
s3 synthesizing a high-strength polyurethane rigid foam plastic preparation:
A. placing ammonium polyphosphate into ethanol, stirring and dissolving, adding a silane coupling agent at 35 ℃, stirring and reacting for 2 hours to obtain a solution A;
B. placing the filler into the solution A, stirring for 3min, pouring the filler into the polyurethane prepolymer at the speed of 30ml/min after stirring is finished, and stirring and reacting for 1h under the reaction condition of 70 ℃ to obtain a material C;
C. placing graphite powder in sulfuric acid, stirring for reaction for 35min, and performing suction filtration and drying to obtain a material D;
D. mixing the material C, the material D, the toluenediamine polyether polyol and deionized water, introducing ozone at the discharge amount of 20L/min, stirring and reacting for 15min at the rotating speed of 400r/min in the nitrogen atmosphere, adding 1-allyl-3-methylimidazole chloride and N, N-dimethylformamide while stirring, and continuously stirring and reacting for 1h to obtain a material E;
E. adding a foaming agent, a foam stabilizer and a catalyst into the material E in sequence, stirring for 10min, standing for 1h, injecting into a mold, curing, then opening the mold, and standing for 18h at room temperature to obtain a rigid polyurethane foam plastic preparation;
s4 preparation of high-hardness polyurethane rigid foam:
A. preparing a coating solution: uniformly stirring acetone, glutamic acid, alanine and pentanediol water solution to obtain coating liquid;
B. and heating the coating liquid to 30 ℃ and keeping the temperature constant, quickly soaking the polyurethane rigid foam plastic prepared body into the coating liquid, reacting for 2h in a low-pressure environment of 0.4atm, taking out and drying for 2h to obtain the high-strength polyurethane foam plastic.
Example 2
The high-strength rigid polyurethane foam plastic comprises the following raw material components: the coating comprises, by weight, 130 parts of toluenediamine polyether polyol, 20 parts of a foaming agent, 20 parts of a foam stabilizer, 200 parts of a polyurethane prepolymer, 20 parts of a catalyst, 25 parts of a filler, 40 parts of graphite powder, 25 parts of sulfuric acid, 30 parts of 1-allyl-3-methylimidazole chloride, 45 parts of ammonium polyphosphate, 30 parts of a silane coupling agent, 30 parts of N, N-dimethylformamide and 65 parts of a coating liquid.
The mass ratio of glutamic acid, alanine and pentanediol in the coating liquid is 8: 3: 1; the hydroxyl value of the toluene diamine polyether polyol is 390mgKOH/g, and the viscosity is 9000 mpa.s.
S1 preparation of polyurethane prepolymer: mixing polymethylene polyphenyl polyisocyanate and polymethylpropylene glycol, and stirring and reacting for 6 hours under a high-pressure condition to obtain a polyurethane prepolymer;
s2 preparation of a filler:
A. soaking the carbon nano tube in the first electrolyte for 30min, putting an aluminum bar electrode, electrifying for 25min, taking out, drying, and pyrolyzing at 650 ℃ for 40min to obtain a material A;
B. soaking the material A in a second electrolyte for 30min, placing an iron rod electrode, electrifying for 25min, adjusting the pH value to 8, and drying to obtain a material B;
C. uniformly mixing the material B and ethanol, and performing ball milling for 45min to obtain a filler;
s3 synthesizing a high-strength polyurethane rigid foam plastic preparation:
A. placing ammonium polyphosphate into ethanol, stirring and dissolving, adding a silane coupling agent at 40 ℃, and stirring and reacting for 2.5 hours to obtain a solution A;
B. placing the filler in the solution A, stirring for 8min, pouring the filler into the polyurethane prepolymer at the speed of 40ml/min after stirring is finished, and stirring and reacting for 1.5h under the reaction condition of 80 ℃ to obtain a material C;
C. placing graphite powder in sulfuric acid, stirring for reaction for 50min, and performing suction filtration and drying to obtain a material D; the invention uses sulfuric acid to carry out intercalation treatment on graphite powder to generate expanded graphite;
D. mixing the material C, the material D, the toluenediamine polyether polyol and deionized water, introducing ozone at the discharge rate of 40L/min, stirring and reacting at the rotating speed of 550r/min for 18min under the nitrogen atmosphere, adding 1-allyl-3-methylimidazole chloride and N, N-dimethylformamide while stirring, and continuously stirring and reacting for 1.5h to obtain a material E;
E. adding a foaming agent, a foam stabilizer and a catalyst into the material E in sequence, stirring for 15min, standing for 1.5h, injecting into a mold, curing, then opening the mold, and standing for 20h at room temperature to obtain a rigid polyurethane foam plastic preparation;
s4 preparation of high-hardness polyurethane rigid foam:
A. preparing a coating solution: uniformly stirring acetone, glutamic acid, alanine and pentanediol water solution to obtain coating liquid;
B. heating the coating liquid to 35 ℃ and keeping the temperature constant, quickly soaking the polyurethane rigid foam plastic prepared body in the coating liquid, reacting for 2.5h in a low-pressure environment of 0.5atm, taking out and drying for 3h to obtain the high-strength polyurethane foam plastic.
Example 3
The high-strength rigid polyurethane foam plastic comprises the following raw material components: the coating comprises, by weight, 150 parts of toluenediamine polyether polyol, 25 parts of a foaming agent, 25 parts of a foam stabilizer, 250 parts of a polyurethane prepolymer, 25 parts of a catalyst, 30 parts of a filler, 50 parts of graphite powder, 30 parts of sulfuric acid, 35 parts of 1-allyl-3-methylimidazole chloride, 60 parts of ammonium polyphosphate, 40 parts of a silane coupling agent, 35 parts of N, N-dimethylformamide and 70 parts of a coating liquid.
The mass ratio of glutamic acid, alanine and pentanediol in the coating liquid is 9: 3: 1; the hydroxyl value of the toluene diamine polyether polyol is 400mgKOH/g, and the viscosity is 9500 mpa.s.
S1 preparation of polyurethane prepolymer: mixing polymethylene polyphenyl polyisocyanate and polymethylpropylene glycol, and stirring and reacting for 7 hours under a high-pressure condition to obtain a polyurethane prepolymer;
s2 preparation of a filler:
A. soaking the carbon nano tube in the first electrolyte for 40min, putting an aluminum bar electrode, electrifying for 35min, taking out, drying, and pyrolyzing at 750 ℃ for 45min to obtain a material A;
B. soaking the material A in a second electrolyte for 40min, placing an iron rod electrode, electrifying for 35min, adjusting the pH value to 9, and drying to obtain a material B;
C. uniformly mixing the material B and ethanol, and performing ball milling for 55min to obtain a filler; the particle size of the filler is further refined through ball milling, the smaller the particle size of the filler is, the stronger the foam stability of the polyurethane rigid foam plastic is, and the better the mechanical property of the generated polyurethane rigid foam plastic is.
S3 synthesizing a high-strength polyurethane rigid foam plastic preparation:
A. placing ammonium polyphosphate into ethanol, stirring and dissolving, adding a silane coupling agent at 45 ℃, and stirring and reacting for 3 hours to obtain a solution A;
B. placing the filler into the solution A, stirring for 10min, pouring the filler into the polyurethane prepolymer at a speed of 50ml/min after stirring is finished, and stirring and reacting for 2h under the reaction condition of 90 ℃ to obtain a material C;
C. placing graphite powder in sulfuric acid, stirring for reaction for 65min, and performing suction filtration and drying to obtain a material D;
D. mixing the material C, the material D, the toluenediamine polyether polyol and deionized water, introducing ozone at the discharge amount of 60L/min, stirring and reacting for 20min at the rotating speed of 700r/min in the nitrogen atmosphere, adding 1-allyl-3-methylimidazole chloride and N, N-dimethylformamide while stirring, and continuously stirring and reacting for 2h to obtain a material E;
E. adding a foaming agent, a foam stabilizer and a catalyst into the material E in sequence, stirring for 20min, standing for 2h, injecting into a mold, curing, then opening the mold, and standing for 24h at room temperature to obtain a rigid polyurethane foam plastic preparation;
s4 preparation of high-hardness polyurethane rigid foam:
A. preparing a coating solution: uniformly stirring acetone, glutamic acid, alanine and pentanediol water solution to obtain coating liquid;
B. heating the coating liquid to 40 ℃ and keeping the temperature constant, quickly soaking the polyurethane rigid foam plastic prepared body in the coating liquid, reacting for 3h in a low-pressure environment of 0.6atm, taking out and drying for 4h to obtain the high-strength polyurethane foam plastic.
And (3) testing:
and (3) testing mechanical properties:
(1) and (3) testing tensile strength: the test is carried out according to the standard GB/T9641-1988 rigid foam plastic tensile property test method.
(2) And (3) testing impact strength: the test is carried out according to GJB1585-93 Experimental method for physical properties of polyurethane rigid foam plastics.
And (3) testing the flame retardant property: the limited oxygen index of the rigid polyurethane foam is tested with reference to GB/T2406.1-2008.
And (3) testing the waterproof performance: the contact angle of the polyurethane rigid foam plastic sample is detected by referring to the test method of GB/T30693-2014.
As can be seen from the data in the table, the tensile strength and the impact strength of the rigid polyurethane foam samples prepared in the examples 1 to 3 are far higher than those of the common rigid polyurethane foam, which shows that the rigid polyurethane foam samples have excellent mechanical properties; meanwhile, the limiting oxygen indexes are all larger than 30%, which shows that the flame retardant has stronger flame retardant capability; the contact angles are all above 90 degrees, which shows that the rigid polyurethane foam plastics prepared in examples 1-3 have stronger hydrophobicity and excellent waterproof and anti-aging properties.
Example 4
The difference from example 3 is that the filler added in this example is a common carbon nanotube, the surface defect of the common carbon nanotube is few, and the compatibility with the rigid polyurethane foam is poor, meanwhile, the common carbon nanotube is difficult to wrap and adsorb ammonium polyphosphate, the ammonium polyphosphate is dissociated in the rigid polyurethane foam, the compatibility between the ammonium polyphosphate and the rigid polyurethane foam is insufficient, and the mechanical property and the flame retardant property of the rigid polyurethane foam prepared are insufficient compared with example 3.
Example 5
The difference from the embodiment 3 is that, in this embodiment, before the ammonium polyphosphate is added, the ammonium polyphosphate does not react with the silane coupling agent, the flame retardancy of the prepared ammonium polyphosphate is reduced, and meanwhile, because of lack of grafting of cations in the silane coupling agent, the ammonium polyphosphate of a single component cannot generate a charge effect with the filler, and further cannot be adsorbed and wrapped in the filler, so that the flame retardancy of the prepared rigid polyurethane foam is further reduced, and the ammonium polyphosphate in a free state in the rigid polyurethane foam also has an influence on the mechanical properties of the rigid polyurethane foam.
Example 6
The difference from the embodiment 3 is that ozone is not introduced into the reaction system when the material E is prepared, and because of lack of ozone, sulfonic acid groups cannot be introduced into the surface of the expanded graphene, the expanded graphite is difficult to compound with the material B through charge, groups such as imidazole and vinyl cannot be grafted on the surface of the expanded graphite to generate macromolecular chains, the compatibility of the material C, the expanded graphite and the rigid polyurethane foam is poor, and the mechanical property of the rigid polyurethane foam prepared is insufficient.
Example 7
The difference from the embodiment 3 is that the polyurethane rigid foam plastic in the invention is soaked in the coating liquid under the normal pressure environment, and because the pores of the polyurethane rigid foam plastic are compact, the coating liquid can not completely permeate into the pores of the polyurethane rigid foam plastic under the normal pressure environment, and the prepared foam plastic has insufficient waterproof performance, thereby easily causing the aging problem.
From the above data and experiments, we can conclude that: (1) the single nano particle can increase the strength of the plastic, but can not increase the flame retardant property of the plastic at the same time, and the filler is obtained by grafting Mg-Al metal hydroxide on the carbon nano tube, so that on one hand, the Mg-Al metal hydroxide can enhance the strength of the carbon nano tube and optimize the mechanical property of the carbon nano tube, thereby indirectly enhancing the mechanical strength of the polyurethane rigid foam plastic; on the other hand, ammonium polyphosphate is introduced into the filler to form a material C, the material C and the expanded graphite with sulfonic groups on the surface are subjected to charge interaction and are compounded together to form a material C/expanded graphite compound, and the compound can provide more active sites for the growth of polyurethane foam and assist in improving the stability of the foam; the macromolecule long chain is introduced to the surface of the material C/expanded graphite compound, so that the material C/expanded graphite compound is entangled with the macromolecule long chain in the polyurethane rigid foam plastic to form a stable network structure, and the mechanical property of the polyurethane rigid foam plastic and the compatibility of the material C/expanded graphite compound in the polyurethane rigid foam plastic are further improved.
(2) According to the invention, ammonium polyphosphate is enclosed in the filler, and when the ammonium polyphosphate is decomposed by heating, the layered structure of the filler on the surface of the ammonium polyphosphate can hinder the exchange of heat and pyrolysis products between flame and a high polymer material, so that the flame retardance of the rigid polyurethane foam plastic is improved; meanwhile, the ammonium polyphosphate wrapped by the filler cannot directly react with the rigid polyurethane foam plastic, and has small influence on the mechanical property and the foam stability of the rigid polyurethane foam plastic.
(3) The polyurethane rigid foam plastic prepared by utilizing the synergistic effects of the components has excellent flame retardant effect, strong mechanical property, good waterproof effect, difficult aging and high practical value
Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A high-strength polyurethane rigid foam plastic is characterized in that: the raw material components are as follows: by weight, 100-25 parts of toluenediamine polyether polyol, 15-25 parts of foaming agent, 15-25 parts of foam stabilizer, 150-250 parts of polyurethane prepolymer, 15-25 parts of catalyst, 20-30 parts of filler, 30-50 parts of graphite powder, 20-30 parts of sulfuric acid, 25-35 parts of 1-allyl-3-methylimidazole chloride, 30-60 parts of ammonium polyphosphate, 20-40 parts of silane coupling agent, 25-35 parts of NN-dimethylformamide and 60-70 parts of coating liquid.
2. A high strength rigid polyurethane foam according to claim 1, wherein: the filler is a modified carbon nanotube with a hydrotalcite structure.
3. A high strength rigid polyurethane foam according to claim 1, wherein: the coating liquid mainly comprises glutamic acid, alanine and pentanediol, and the mass ratio of the glutamic acid to the alanine to the pentanediol is (7-9): 3: 1.
4. a high strength rigid polyurethane foam according to claim 1, wherein: the toluene diamine polyether polyol is prepared by the addition reaction of toluene diamine serving as an initiator, propylene oxide and ethylene oxide; the hydroxyl value of the toluene diamine polyether polyol is 370-400mgKOH/g, and the viscosity is 8500-9500mpa.
5. The preparation method of the high-strength rigid polyurethane foam plastic is characterized by comprising the following steps:
s1 preparation of polyurethane prepolymer: mixing polymeric isocyanate and polymethyl propylene glycol, and stirring for reaction under a high-pressure condition to obtain a polyurethane prepolymer;
s2, preparing a filler;
s3 synthesizing a high-strength polyurethane rigid foam plastic preparation:
A. placing ammonium polyphosphate into ethanol, stirring and dissolving, and adding a silane coupling agent to obtain a solution A;
B. placing the filler into the solution A, stirring, pouring the filler into a polyurethane prepolymer after stirring, and stirring for reaction to obtain a material C;
C. putting graphite powder into sulfuric acid, stirring, and performing suction filtration and drying to obtain a material D;
D. mixing the material C, the material D, the toluenediamine polyether polyol and deionized water, adding 1-allyl-3-methylimidazole chloride and N, N-dimethylformamide while stirring in a nitrogen atmosphere, and continuously stirring for reaction to obtain a material E;
E. adding a foaming agent, a foam stabilizer and a catalyst into the material E in sequence, stirring, standing, injecting into a mold, curing, then opening the mold, and standing at room temperature to obtain a polyurethane rigid foam plastic preparation;
s4 preparation of high-hardness polyurethane rigid foam:
A. preparing a coating solution: uniformly stirring acetone, glutamic acid, alanine and pentanediol water solution to obtain coating liquid;
B. and quickly soaking the polyurethane rigid foam plastic preparation body in the coating liquid, taking out and drying to obtain the high-strength polyurethane rigid foam plastic.
6. The method for preparing the high-strength rigid polyurethane foam plastic as claimed in claim 5, which comprises the following steps:
s1 preparation of polyurethane prepolymer: mixing polymeric isocyanate and polymethyl propylene glycol, and stirring and reacting for 4-7h under a high-pressure condition to obtain a polyurethane prepolymer;
s2, preparing a filler;
s3 synthesizing a high-strength polyurethane rigid foam plastic preparation:
A. placing ammonium polyphosphate into ethanol, stirring and dissolving, adding a silane coupling agent at 35-45 ℃, and stirring and reacting for 2-3h to obtain a solution A;
B. placing the filler into the solution A, stirring for 3-10min, pouring the filler into the polyurethane prepolymer at the speed of 30-50ml/min after stirring, and stirring to react for 1-2h under the reaction condition of 70-90 ℃ to obtain a material C;
C. placing graphite powder in sulfuric acid, stirring to react for 35-65min, and performing suction filtration and drying to obtain a material D;
D. mixing the material C, the material D, the toluenediamine polyether polyol and deionized water, stirring and reacting for 15-20min at the rotating speed of 700r/min in the nitrogen atmosphere, adding the 1-allyl-3-methylimidazole chlorine salt and the N, N-dimethylformamide while stirring, and continuously stirring and reacting for 1-2h to obtain a material E;
E. adding a foaming agent, a foam stabilizer and a catalyst into the material E in sequence, stirring for 10-20min, standing for 1-2h, injecting into a mold, curing, then opening the mold, and standing at room temperature for 18-24h to obtain a rigid polyurethane foam plastic preparation;
s4 preparation of high-hardness polyurethane rigid foam:
A. preparing a coating solution: uniformly stirring acetone, glutamic acid, alanine and pentanediol water solution to obtain coating liquid;
B. heating the coating liquid to 30-40 ℃ and keeping the temperature constant, quickly soaking the polyurethane rigid foam plastic preparation body in the coating liquid, reacting for 2-3h under a low-pressure environment, taking out and drying for 2-4h to obtain the high-strength polyurethane rigid foam plastic.
7. The method for preparing a high-strength rigid polyurethane foam according to claim 6, wherein: step D of step S3 is to introduce ozone while stirring, and the ozone discharge amount is 20-60L/min; and in the step S4, the pressure of the low-pressure environment is 0.4-0.6 atm.
8. The method for preparing a high-strength rigid polyurethane foam according to claim 6, wherein: the preparation method of the filler comprises the following steps: (1) soaking the carbon nano tube in the first electrolyte for 20-40min, putting an aluminum bar electrode, electrifying for 15-35min, taking out, drying, and pyrolyzing for 35-45min to obtain a material A; (2) soaking the material A in a second electrolyte for 20-40min, placing an iron rod electrode, electrifying for 15-35min, adjusting pH to 7-9, and drying to obtain a material B; (3) and uniformly mixing the material B and ethanol, and performing ball milling for 35-55min to obtain the filler.
9. The method for preparing a high-strength rigid polyurethane foam according to claim 8, wherein: the preparation method of the filler comprises the following steps: the first electrolyte in the step (1) is sodium chloride; the second electrolyte in the step (2) is magnesium chloride.
10. The method for preparing a high-strength rigid polyurethane foam according to claim 8, wherein: the pyrolysis temperature in the step (2) is 550-750 ℃.
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