CN114957658A - Polycondensation type thermosetting resin prepolymer and application method thereof - Google Patents
Polycondensation type thermosetting resin prepolymer and application method thereof Download PDFInfo
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Abstract
The invention discloses a polycondensation type thermosetting resin prepolymer and an application method thereof, the invention takes melamine and hexamethylene diamine as raw materials, and the melamine-hexamethylene diamine polycondensation type thermosetting resin prepolymer is prepared under the action of an acid catalyst and at the temperature of 180-215 ℃, wherein the molar ratio of hexamethylene diamine to melamine is 1.2-1.8: 1; the melamine-hexamethylene diamine condensation type thermosetting resin prepolymer is subjected to vacuum pre-curing treatment and compression molding to prepare a colorless or light yellow transparent condensation type thermosetting resin material, and various additives and fibers are added to prepare plastics and composite materials with various functions; the invention obtains the thermosetting characteristic, the processing property and the mechanical property of the final material of the resin by strictly controlling the material ratio, and the polycondensation type thermosetting resin and the composite material thereof provided by the invention have excellent thermal stability, mechanical property and ultralow temperature tolerance.
Description
Technical Field
The invention belongs to the technical field of high-molecular polymer preparation, and particularly relates to preparation of a polycondensation type thermosetting resin prepolymer, a processing and forming method of the polycondensation type thermosetting resin prepolymer, and a method for preparing a composite material by using the processing and forming method.
Background
The German chemist Bayer found for the first time that phenol and aldehyde can generate high molecular polymer in 1872, but no research is carried out. Until 1907, united states scientist bucklan filed for a patent on the heat and pressure curing of phenolic resins, and realized the practical use of phenolic resins. Since then, resins and their composite materials are widely used in various fields of national economy, on the one hand, replacing some traditional materials, such as metals, ceramics, wood, etc. On the other hand, they have been developed in new fields, such as aerospace, military, nuclear industry and information technology, due to their advantages of light weight, high specific strength, low cost, etc. However, the current research on the resin and the composite material thereof is mainly based on phenolic resin, epoxy resin, polyurethane resin, polyamide resin, unsaturated polyester, polypropylene resin, acrylic resin, and the like. High-performance resins and composites thereof with novel structures are rarely reported.
CN 114479447A provides a high-strength glass fiber composite material and a preparation method thereof, wherein the matrix resin is polyamide 66, and mechanical properties such as notch impact strength, tensile strength and flexural modulus of the composite material are improved by adding some auxiliary agents and modifiers. In addition, by adding the potassium titanate whisker, the noise value of the composite material is further reduced while the good mechanical property of the original composite material is maintained, so that the overall composite material achieves the effects of low noise, high strength and wear resistance. CN 114105525A discloses a flame-retardant glass fiber composite material and a preparation method thereof. The flame-retardant glass fiber composite material comprises the glass fiber composition and the epoxy resin base material glue solution, the melting point of the glass fiber can be reduced on the premise that the performance of the glass fiber is not affected, the flame retardance is enhanced, smooth wire drawing is ensured, and the prepared glass fiber composite material is good in fire resistance. The glass fiber composite material is prepared by taking traditional polyamide resin or epoxy resin as a matrix, is limited by inherent defects of the matrix resin, such as low thermal decomposition temperature, low temperature brittleness, poor interface compatibility and the like, and is difficult to meet the performance requirements under extreme conditions. High-performance special resins (such as polyimide, polyether-ether-ketone and the like) have excellent comprehensive performance, but the market price is very high at present, and products with independent intellectual property rights in China are still very deficient and depend on a large number of imports.
JP4605328B2 provides a process for the synthesis of alkyldimelamine from melamine and diamines in the presence of an acidic catalyst, the molar ratio of melamine to diamine having to be greater than 2, and the reaction temperature being 120 ℃ and 250 ℃. In EP0240867B1 tris- (6-aminohexyl) melamine was synthesized using melamine and 1, 6-hexamethylenediamine (abbreviated to hexamethylenediamine) at 120-300 ℃ and preferably 160-250 ℃ and in the examples 210 ℃ using acidic catalysts, in which reaction relatively pure tris- (6-aminohexyl) melamine was obtained at a molar ratio of melamine to hexamethylenediamine of 1:20 and hexamethylenediamine terminated polymers were obtained at lower molar ratios. CN 101679630a discloses a method for preparing a multi-branched melamine polymer, wherein 1.5 to 4.0 mol of one or more diamines or polyamines per mol of melamine is reacted in the presence of an acidic catalyst, wherein 2 to 3mol of amine is reacted per mol of melamine, and the multi-branched melamine polymer is used as an epoxy resin curing agent. To form the dendritic structure, melamine is added in steps, and a highly symmetrical, highly branched, low cross-linking structure has been obtained. The above disclosed method for synthesizing polymers from melamine and di-or polyamines gives aliphatic amine-terminated low molecular weight polymers or dendritic multi-branched polymers. Because of the single kind of end groups, these polymers do not have the structural features and properties of thermosetting resins and cannot be cross-linked and cured at high temperature to form a bulk network structure, i.e., an insoluble and infusible cured product.
As in the development history of phenol-formaldehyde resins, although polymers synthesized from melamine and hexamethylenediamine have been reported as early as 1992 (EP 0240867B 1), reports on the synthesis of thermosetting resins therefrom have not been made so far. The synthesis of thermosetting resins from melamine and hexamethylenediamine and their shaping techniques present several difficulties: 1. the physicochemical property of the high molecular polymer is often directly related to the material proportion used in synthesis, and the thermosetting resin with excellent performance can be obtained only by strictly regulating and controlling the material proportion; 2. the melamine-hexamethylene diamine resin belongs to polycondensation type thermosetting resin, gas is continuously released in the whole curing process, so that great difficulty in material processing is caused, and if the processing method is not proper, the final material has more defects; 3. the curing and crosslinking between melamine and hexamethylene diamine can be carried out under the harsh temperature condition, and the curing process is long; 4. since this is a novel resin, the processing conditions are not readily known from experience. It is precisely because of the harsh conditions of resin structure formation and curing that it is highly likely to achieve a very good overall performance once processed into a material. However, prior to the present invention, the properties of such materials have never been disclosed by the relevant literature.
Based on the facts, the technical breakthrough that the thermosetting resin is synthesized by taking melamine and hexamethylene diamine as raw materials, so that the thermosetting resin has the processing performance, and finally, the compact and low-defect-rate resin material is obtained is undoubtedly the premise of realizing the application. Once the material processing method is established, the preparation technology of the composite material related to the material processing method is easy to break through.
Disclosure of Invention
The invention provides a polycondensation type thermosetting resin prepolymer, a processing forming method thereof and a preparation method of a composite material, breaks through the bottleneck of application of resin as a high-performance material, and can effectively supplement the defects of the traditional resin and the composite material by the resin, the processing technology thereof and the preparation method of the composite material.
In order to achieve the above object, the present invention provides the following technical solutions:
1. synthesis of melamine-hexamethylene diamine polycondensation type thermosetting resin prepolymer
According to the molar ratio of 1.2-1.8: 1 of hexamethylenediamine to melamine, heating hexamethylenediamine (H) to 45-55 ℃, fully mixing the hexamethylenediamine with melamine (M), adding an acid catalyst (such as ammonium chloride, hydrochloric acid, sulfuric acid and ammonium sulfate), heating to 180-215 ℃ for reaction, reacting until the viscosity of the system is obviously increased and the transparency is increased, and simultaneously observing that a large amount of bubbles are generated, thereby obtaining the melamine-hexamethylenediamine polycondensation type thermosetting resin prepolymer.
Theoretically, when an H-terminated polymer with molecular weight approaching infinity is synthesized, as shown in formula I, the molar ratio of H/M satisfies the limit formula:
= 2; when synthesizing a polymer with the molecular weight of M end capping approaching infinity, as shown in a formula II, the molar ratio of H/M satisfies a limit formula:
=1, wherein n refers to the number of M units in the polymer. When the molar ratio of H/M is more than 2.0 or less than 1.0, it is possible to cause M or H to be completely or largely blocked, at which time the product does not have structural characteristics of a thermosetting resin and cannot be cured.
The synthetic thermosetting resin of melamine and hexamethylene diamine requires that the structure of the synthetic thermosetting resin contains primary amino and mono-substituted melamine or primary amino and di-substituted melamine in proper proportion, as shown in a formula III;
formula I:
formula II:
formula III:
therefore, in the case of the synthetic resin of the present invention, the molar ratio (H: M) of hexamethylenediamine to melamine should be controlled to be 1.0 to 2.0, preferably 1.2 to 1.8, and the terminal of the branch of the prepolymer simultaneously has primary amino group, mono-substituted melamine and/or di-substituted melamine:
the melamine-hexamethylene diamine condensation type thermosetting resin prepolymer prepared by the method can be used as a structural adhesive for bonding metal and nonmetal materials such as steel, copper, aluminum, ceramics, glass and carbon fiber composite boards, and the curing temperature is preferably 250-270 ℃.
2. Processing and forming method of polycondensation type thermosetting resin prepolymer
Placing the melamine-hexamethylenediamine polycondensation type thermosetting resin prepolymer prepared in the step 1 in a vacuum drying oven, and keeping the vacuum drying oven at a vacuum degree of-0.05 to-0.08 MPa and at a temperature of 180 to 200 ℃ for 6 to 10 hours to remove ammonia and residual reactants in the resin and further perform polycondensation on the resin prepolymer; and then placing the mixture into a stainless steel mold, keeping the mixture for 30min at the temperature of 200-220 ℃ and the mold pressing pressure of 0.5-1 MPa by using a hot press, exhausting, raising the temperature from 200-220 ℃ to 270-300 ℃ by adopting a temperature programming or step raising mode, raising the mold pressing pressure by 0.5-0.6 MPa at each raising temperature of 10 ℃, keeping the mixture for 2-5 h at the temperature of 3.5-4.5 MPa and 270-300 ℃, exhausting once every 10-15 min during the process, keeping the pressure to naturally cool to the room temperature, and demolding to obtain the colorless or faint yellow transparent melamine-hexamethylene diamine polycondensation type thermosetting resin.
The continuous heating is carried out at a heating rate of 1-2 ℃/min to 270-300 ℃; the step heating is carried out by heating to 270-300 ℃ every 5-10 min at a temperature of 5-10 ℃.
During the processing and forming process of the melamine-hexamethylene diamine polycondensation type thermosetting resin prepolymer, various conventional additives such as stabilizing additives, mechanical property improving additives, color light changing additives, flame retardant and smoke suppression additives can be added to prepare engineering plastics suitable for various requirements.
3. Application of polycondensation type thermosetting resin prepolymer in preparation of composite material
(1) Dissolving melamine-hexamethylene diamine condensation type thermosetting resin prepolymer into a solution with the mass concentration of 20-50% by using an ethanol-water solvent; fully soaking the glass fiber or carbon fiber braided fabric into the solution, removing the solvent in a vacuum drying oven, placing the solution into a stainless steel mold, preserving the heat for 1-2 hours at 220-230 ℃, and then keeping the temperature for 30-60 minutes at 220-230 ℃ under the mold pressing pressure of 0.5-1 MPa, and exhausting; and then raising the temperature and boosting the pressure, raising the mould pressing pressure by 0.5-0.6 MPa at a temperature of 10 ℃ per liter, keeping the temperature for 5-10 min, then performing primary exhaust, raising the temperature and boosting the pressure again until the temperature is 270-300 ℃, finally pressing for 50-80 min at the mould pressing pressure of 3.5-4.5 MPa, and keeping the pressure to naturally cool to the room temperature to obtain the resin-based glass fiber composite material or the resin-based carbon fiber composite material.
(2) Dissolving a melamine-hexamethylene diamine polycondensation type thermosetting resin prepolymer into a solution with the mass concentration of 5-15% by using an ethanol-water solvent, soaking a carbon fiber woven fabric, carbon paper or carbon felt into the solution, removing the solvent in a vacuum drying oven, placing the soaked matter between two layers of polytetrafluoroethylene sheets, keeping the two layers of polytetrafluoroethylene sheets at 220-230 ℃ and the mould pressing pressure of 1-2 MPa for 10-20 min, cooling, and taking out to obtain a pre-cured sheet or plate; then placing the pre-cured sheet or plate between two layers of stainless steel sheets, putting the sheet or plate into a press, raising the pressure to 4-5 MPa, raising the temperature to 270-300 ℃ at a rate of 5-10 ℃/min, keeping the temperature for 3-5 min, keeping the pressure, naturally cooling, and taking out to obtain a carbon fiber resin composite sheet or plate (laminated sheet); the carbon fiber-resin composite sheet or plate is carbonized and graphitized to obtain the carbon fiber-graphite composite material with excellent conductivity, the graphitized sheet with the thickness of 0.15-0.30 mm and the surface resistance of 6-11 m omega cm.
The ethanol-water solvent is prepared by mixing ethanol and water according to the volume ratio of 2.5-1: 1.
The invention has the advantages and technical effects that:
1. according to the invention, the molecular branch chain end of the prepared prepolymer is simultaneously provided with primary amino, primary substituted melamine and/or secondary substituted melamine by strictly controlling the molar ratio of the raw materials, so that the prepolymer can be cured at high temperature and has adhesive property and processability;
2. after being cured, the resin prepolymer disclosed by the invention has excellent room-temperature and ultralow-temperature bonding properties on metal and non-metal materials, can be used as a structural adhesive, and has the room-temperature bonding property equivalent to that of commercial epoxy resin and the ultralow-temperature bonding property equivalent to that of polyurethane adhesive;
3. the resin prepolymer solves the problem of difficult material processing caused by continuous gas release in the curing process by a method of vacuum pre-curing treatment and compression molding (a heating procedure, a boosting procedure and an exhaust procedure), and thermosetting resin with excellent acid-base and organic solvent resistance is obtained, wherein the room-temperature tensile strength of a resin cured product obtained by the method is 50-80 MPa, and the elongation at break is 12-15%; when the resin is compressed, the resin has an obvious yield phenomenon, the yield strength is 150-200 MPa, and the strain of the yield point is 20-25%. The tensile and compressive test results show that the resin material has excellent toughness. A test result of immediately carrying out tensile strength or compressive strength after a test piece is immersed in liquid nitrogen (-196 ℃) for 5min shows that the retention rate of the mechanical strength of the resin is 90-97%, which indicates that the resin is not embrittled in an ultralow temperature environment. Thermogravimetric (TGA) analysis shows that the maximum thermal decomposition temperature of the cured resin is 470-497 ℃, and a high temperature resistance test of the cured resin material shows that the material is stable in size after being subjected to heat treatment for 30min at 400 ℃ under the protection of nitrogen, and still has transparency, which indicates that the heat resistance of the resin is excellent. Further tests show that the glass transition temperature of the resin is about 100 ℃, and the thermal deformation temperature is 100-120 ℃.
The resin-based glass fiber composite material or resin-based carbon fiber composite material prepared by the melamine-hexamethylene diamine polycondensation type thermosetting resin prepolymer can be used for obtaining composite boards with different thicknesses and densities by controlling the concentration of the dipping glue solution, the number of fabric layers and the mould pressing pressure. The mechanical strength test result shows that the vertical layer bending strength of the grid glass fiber cloth composite laminated material is 350-550 MPa; the bending strength of the vertical layer direction of the bidirectional carbon fiber cloth composite laminated material is 680-750 MPa; the thermal deformation temperature of the two composite materials is 290-310 ℃, and the two composite materials are not embrittled at ultralow temperature (-196 ℃).
Due to excellent comprehensive performance, the composite material has remarkable application prospect in the fields of aerospace, electronics, automobiles, machinery, superconduction and the like; the graphitized sheet with the thickness of 0.15-0.30 mm, which is prepared from carbon paper and melamine-hexamethylene diamine condensation type thermosetting resin prepolymer, has the surface resistance of 6-11 m omega cm, and has better application prospects in the fields of fuel cell manufacturing, catalysis and the like.
The synthesis method of the resin prepolymer, the molding processing method of the resin material and the preparation method of the composite material can provide basic technical data for industrial large-scale production (such as the production of the composite material by using an autoclave).
Drawings
FIG. 1 is a schematic representation of hexamethylenediamine 13 C-NMR spectrum
FIG. 2 is a diagram of melamine 13 C-NMR spectrum
FIG. 3A diagram of a melamine-hexamethylenediamine polycondensation type thermosetting resin prepolymer 13 C-NMR spectrum
FIG. 4 is an infrared absorption spectrum of a cured product of a polycondensation type thermosetting resin obtained by the machine-shaping method of the present invention;
FIG. 5 is a thermogravimetric analysis result of a cured product of a melamine-hexamethylenediamine polycondensation type thermosetting resin;
FIG. 6 is a graph showing the results of transparency of the processed resin material of the present invention after Room Temperature (RT) and high temperature treatment;
FIG. 7 is a comparison of the high temperature resistance of glass fiber composites made according to the present invention with several commercial glass fiber composites, the top view being a front or side view before high temperature treatment, the bottom view being a front or side view after high temperature treatment, in which GF-MH (25 layers), GF-MH (20 layers) are the materials made according to the method of the present invention, FR-4 epoxy boards (1 and 2) and 3240 epoxy boards are commercial epoxy resin based glass fiber composite laminates, and PF is a commercial phenolic resin board;
fig. 8 is a raman spectrum of the carbon fiber-graphite composite material;
fig. 9 is a scanning electron microscope image of the carbon fiber-graphite composite material.
Detailed Description
The present invention is further illustrated by the following examples, but the scope of the invention is not limited to the above-described examples.
Example 1: synthesis of melamine-hexamethylene diamine polycondensation type thermosetting resin prepolymer
Adding 208.8g of hexamethylenediamine (H) into a round-bottom flask, melting at 50 ℃, adding 126.1g of melamine (M) into the hexamethylenediamine under stirring, uniformly mixing, adding 7.6g of ammonium chloride, heating in an oil bath to 200 ℃, reacting until the viscosity of the system is increased and a large amount of bubbles are generated, and immediately stopping the reaction to obtain a melamine-hexamethylenediamine polycondensation type thermosetting resin prepolymer;
FIG. 1, FIG. 2 and FIG. 3 are respectively the NMR spectra of hexamethylenediamine, melamine and melamine-hexamethylenediamine polycondensation type thermosetting resin prepolymer 13 Spectrum C ( 13 C-NMR); the common peak (39-40 ppm) in the 3 spectra is the solvent peak of deuterated dimethyl sulfoxide (DMSO-d 6). Control of the 3 spectra shows that the chemical shifts of the triazine ring carbon atoms of melamine are changed by substitution of the amino groups and split, moving from 167.69ppm of melamine to 166.78ppm, 166.45ppm and 166.03ppm in the polymer. Wherein 166.03 corresponds to mono-substituted melamine at the end of a polymer branch, 166.45 corresponds to di-substituted melamine at the end of a polymer branch, and 166.78 corresponds to tri-substituted melamine within the polymer. In addition, a methylene thermogram control of hexamethylenediamine showed three peaks for hexamethylenediamine, 42.08ppm, 32.93ppm and 26.80ppm, where 42.08ppm corresponds to the carbon atom directly attached to the amino group. A new peak at 29.91ppm of the polymer indicated that some of the hexamethylenediamine had condensed with the melamine, while a peak at 41.35ppm corresponded to the carbon atoms of the polymer directly linked to the unreacted amino groups, indicating that some of the hexamethylenediamine amino groups had not reacted. As described above 13 The C-NMR spectrum sufficiently shows that the polymer branch chain end is simultaneously provided with the self-cross-linkingPrimary amino groups of diamines and mono-and/or di-substituted melamines.
According to the test method of the national standard GB/T7142-2008, the melamine-hexamethylene diamine polycondensation type thermosetting resin prepolymer prepared in the embodiment is coated on the surface of a base material, and then is cured at 250 ℃ for 10-20 min to obtain the bonding performance; the test result shows that the average shear strength of the adhesive for stainless steel, aluminum, copper and carbon fiber is respectively 21MPa, 19MPa, 15MPa and 16MPa at room temperature, the adhesive strength for glass is more than 15MPa (test piece fracture), and the adhesive strength for wood is more than 9MPa (test piece fracture); the average shear strength of the bonded stainless steel test piece under the liquid nitrogen condition (-196 ℃) is about 17 MPa; the strength of the bonded stainless steel is 10MPa and 7MPa respectively when tested at the temperature of 100 ℃ and 120 ℃, and the average bonding strength is 1.9MPa when tested in the range of 200-300 ℃.
Example 2: synthesis of melamine-hexamethylene diamine polycondensation type thermosetting resin prepolymer
Adding 174.3g of hexamethylenediamine into a round-bottom flask, melting at 50 ℃, adding 126.1g of melamine into the hexamethylenediamine under stirring, uniformly mixing, adding 7.6g of ammonium chloride, heating to 200 ℃ in an oil bath, reacting until the viscosity of the system is increased and a large amount of bubbles are generated, and immediately stopping the reaction to obtain the melamine-hexamethylenediamine polycondensation type thermosetting resin prepolymer;
according to the test method of the national standard GB/T7142-2008, the melamine-hexamethylene diamine polycondensation type thermosetting resin prepolymer prepared in the embodiment is smeared on the surface of stainless steel, and is cured for 10min at 270 ℃ to obtain the bonding performance; the room temperature bonding shear strength is tested according to the test method of national standard GB/T7142-2008, and the result is 14 MPa.
Example 3: processing and forming method for polycondensation type thermosetting resin prepolymer
Placing the melamine-hexamethylenediamine polycondensation type thermosetting resin prepolymer prepared in the example 1 in a vacuum drying oven, preserving heat for 8h at 200 ℃ under the vacuum degree of-0.07 MPa, then placing the prepolymer in an experimental stainless steel mold (the mold size is 5cm multiplied by 10cm multiplied by 5 cm), using a hot press to keep the mold pressing pressure at 200 ℃ and 1MPa for 30min, then exhausting gas, then adopting a step heating mode, raising the temperature to 270 ℃ from 200 ℃ every 5min, simultaneously raising the mold pressing pressure by 0.5MPa every 10 ℃ and exhausting gas once every 10min, finally keeping the mold pressing pressure at 4.5MPa and 270 ℃ for 5h, keeping the pressure until the mold is naturally cooled to room temperature, and demolding to obtain the faint yellow transparent melamine-hexamethylenediamine polycondensation type thermosetting resin.
The mechanical strength of the polycondensation type thermosetting resin obtained in the embodiment is tested by referring to the testing methods of national standards GB/T1040.1-2018 and GB/T1041-2008, the room temperature tensile strength of the obtained resin is 70MPa, the elongation at break is 13%, when the resin is compressed, the resin has an obvious yield phenomenon, the yield strength is 160MPa, and the strain of the yield point is 20%; the tensile or compressive test is carried out immediately after the test piece is immersed in liquid nitrogen (-196 ℃) for 5min, and the result shows that the retention rate of the mechanical strength of the resin is 95%, which indicates that the resin is not embrittled in an ultralow temperature environment; the thermal deformation temperature is 100-110 ℃, the maximum thermal decomposition temperature is 483 ℃, the infrared absorption spectrum is shown as figure 4, the thermogravimetric analysis result is shown as figure 5, and the room temperature transparency and the high temperature transparency of the cured resin are shown as figure 6.
Example 4: preparation of polycondensation type thermosetting resin material with flame-retardant function
Adding 30% by mass of aluminum hydroxide serving as a flame retardant into the melamine-hexamethylene diamine polycondensation type thermosetting resin prepolymer prepared in the embodiment 1, uniformly stirring at 160 ℃, and then preparing the melamine-hexamethylene diamine polycondensation type thermosetting resin material with the flame retardant function according to the pressure forming method in the embodiment 2, wherein the resin material can pass the UL-94V-0 level flame retardant test.
Example 5: preparation of resin-based glass fiber cloth laminated composite material
Dissolving the melamine-hexamethylene diamine condensation type thermosetting resin prepolymer prepared in example 1 into a solution with the mass concentration of 40% by using an ethanol-water solvent (the volume ratio is 2.5: 1); then, 7628 type alkali-free glass fiber cloth (15 cm. times.15 cm, thickness 0.2 mm) was sufficiently impregnated with the above solution, the solvent was removed in a vacuum drying oven, 20 or 25 layers of the impregnated material were placed in a stainless steel mold for laboratory use and heat-insulated at 220 ℃ for 2 hours, and then 50mi was maintained at 220 ℃ under a molding pressure of 0.5MPaExhausting after n; then raising the temperature and boosting the pressure, raising the mould pressing pressure by 0.5MPa at the temperature of 10 ℃ per liter, keeping the temperature for 10min, then carrying out primary exhaust, raising the temperature, boosting the pressure and exhausting again until the temperature is 290 ℃, the mould pressing pressure is 4.0MPa, pressing for 60min, and naturally cooling to room temperature by keeping the pressure to obtain the resin-based glass fiber laminated composite material; the thickness of the 20 layers of the composite material is 3.3-3.5 mm, and the density is 1.7-1.8 g/cm 3 The thickness of the 25 layers of the composite material is 4.4-4.5 mm, and the density is 1.6-1.7 g/cm 3 (ii) a The thermal deformation temperature of the composite material is 290-310 ℃.
The glass fiber composite laminates (GF-MH (25 layers) and GF-MH (20 layers)) prepared in this example and several commercial glass fiber composite laminates (FR-4 epoxy plate 1, FR-4 epoxy plate 2, PF resin plate and 3240 epoxy plate) were placed at 425 ℃ under a nitrogen atmosphere, and then cooled and taken out after being maintained for 30min, and the comparative effect is shown in FIG. 7, which shows that the composite prepared in this example has no interlayer separation, fracture or carbonization, but other composites have obvious interlayer separation, fracture or carbonization.
The bending strength of the composite material obtained in the embodiment and several commercial glass fiber composite materials is tested by referring to a test method of national standard GB/T1449-.
Implementation benefit 6: preparation of resin-based carbon fiber cloth laminated composite material
The preparation method of this example is the same as example 4, except that 3K bidirectional carbon fiber cloth (200 g/m) is adopted 2 ) The bending strength of the composite material obtained in the embodiment is tested by referring to the test method of GB/T1449-.
Example 7: preparation of carbon fiber-graphite composite material
The melamine-hexamethylenediamine polycondensation type thermosetting resin prepolymer obtained in example 1 was dissolved in an ethanol-water solvent (volume ratio: 2.5: 1) to obtain a solutionA 10% strength solution, and then a carbon paper (40 g/m) 2 0.6mm in thickness) of a sheet, cutting the sheet into a size of 15cm × 15cm, immersing the sheet in the solution, removing the solvent in a vacuum drying oven, placing the immersed sheet between two layers of polytetrafluoroethylene sheets, hot-pressing the sheet at 220 ℃ and 1MPa for 20min, cooling the sheet, taking out the sheet to obtain a pre-cured sheet, placing the pre-cured sheet between two layers of stainless steel sheets, placing the sheet in a press, increasing the pressure to 4MPa, increasing the temperature to 270 ℃ at a rate of 5 ℃/min, keeping the temperature for 5min, naturally cooling the sheet under the maintained pressure to obtain a carbon fiber-resin composite sheet, carbonizing and graphitizing the carbon fiber-resin composite sheet to obtain a carbon fiber-graphite composite material having a thickness of 0.2 to 0.25mm and a raman spectrum of fig. 8, and a Scanning Electron Microscope (SEM) image of fig. 9, measuring the carbon fiber-graphite composite sheet by using a resistivity measuring instrument, the surface resistance is 10-11 m omega cm.
In conclusion, the polycondensation thermosetting resin and the composite material prepared by the method have excellent mechanical property, thermal stability, ultralow temperature tolerance and conductivity.
The foregoing description shows and describes several preferred embodiments of the present application, but as aforementioned, it is to be understood that the present application is not limited to the forms disclosed herein, but is not to be construed as excluding other embodiments and is capable of numerous other combinations, modifications, and variations within the scope of the inventive concept as expressed herein, commensurate with the above teachings, or the skill or knowledge of the relevant art. And that modifications and variations may be effected by those skilled in the art without departing from the spirit and scope of the application, which is to be protected by the claims appended hereto.
Claims (10)
1. A polycondensation type thermosetting resin prepolymer is characterized in that: the melamine-hexamethylene diamine polycondensation type thermosetting resin prepolymer is prepared by taking melamine and hexamethylene diamine as raw materials and reacting at 180-215 ℃ under the action of an acid catalyst, wherein the molar ratio of the hexamethylene diamine to the melamine is 1.2-1.8: 1.
2. The polycondensation type thermosetting resin prepolymer according to claim 1, wherein: the end of the branch chain of the prepolymer simultaneously has primary amino group, primary substituted melamine and/or secondary substituted melamine.
3. Use of the polycondensation type thermosetting resin prepolymer according to any one of claims 1 to 2 as a structural adhesive.
4. The method for processing and molding a polycondensation type thermosetting resin prepolymer according to claim 1, wherein: the melamine-hexamethylene diamine condensation type thermosetting resin prepolymer is subjected to vacuum pre-curing and compression molding to obtain a completely cured colorless or light yellow transparent resin material.
5. The method for processing and molding polycondensation type thermosetting resin prepolymer according to claim 4, wherein: the melamine-hexamethylenediamine polycondensation type thermosetting resin prepolymer is subjected to heat preservation for 6-10 hours under the conditions of vacuum degree of-0.05 to-0.08 MPa and temperature of 180-200 ℃, then placed in a stainless steel mold, kept for 30 minutes at 200-220 ℃ and mold pressing pressure of 0.5-1 MPa by using a hot press, then exhausted, then raised from 200-220 ℃ to 270-300 ℃ in a continuous heating or step heating mode, simultaneously raised from 0.5-0.6 MPa at every 10 ℃ rise, finally kept for 3-5 hours at the mold pressing pressure of 3.5-4.5 MPa and the temperature of 270-300 ℃, and exhausted once every 10-15 minutes, then kept at the pressure, naturally cooled to room temperature, and demoulded to obtain the colorless or light yellow transparent melamine-hexamethylenediamine polycondensation type thermosetting resin material.
6. The method for processing and molding a polycondensation type thermosetting resin prepolymer according to claim 5, wherein: the continuous heating is carried out at a heating rate of 1-2 ℃/min to 270-300 ℃; the step heating is carried out by heating to 270-300 ℃ every 5-10 min at a temperature of 5-10 ℃.
7. The method for processing and molding a polycondensation type thermosetting resin prepolymer according to claim 6, wherein: one or more of stabilizing auxiliary agent, mechanical property improving auxiliary agent, color light changing auxiliary agent, flame retardant and smoke suppression auxiliary agent are added into the melamine-hexamethylene diamine polycondensation type thermosetting resin prepolymer.
8. The method for preparing the composite material by adopting the polycondensation type thermosetting resin prepolymer of claim 1 is characterized by comprising the following steps: dissolving melamine-hexamethylenediamine polycondensation type thermosetting resin prepolymer into a solution with the mass concentration of 20-50% by using an ethanol-water solvent, fully soaking a glass fiber or carbon fiber woven fabric in the solution of the prepolymer, then placing the soaked solution in a vacuum drying oven to remove the solvent, placing the soaked solution in a stainless steel mold, keeping the temperature of the stainless steel mold at 220-230 ℃ for 1-2 hours, keeping the temperature of the stainless steel mold at 220-230 ℃ under the mold pressing pressure of 0.5-1 MPa for 30-60 minutes, and then exhausting; and then raising the temperature and boosting the pressure, raising the mould pressing pressure by 0.5-0.6 MPa and keeping the mould pressing pressure for 5-10 min every time the temperature is raised by 10 ℃, then carrying out primary exhaust, raising the temperature and boosting the pressure again and exhausting the gas until the temperature is 270-300 ℃, the mould pressing pressure is 3.5-4.5 MPa, keeping the temperature for 50-80 min, and then keeping the pressure and naturally cooling to the room temperature to obtain the resin-based glass fiber laminated composite material or the resin-based carbon fiber composite material.
9. The method for preparing the composite material by adopting the polycondensation type thermosetting resin prepolymer of claim 1 is characterized by comprising the following steps: dissolving a melamine-hexamethylene diamine polycondensation type thermosetting resin prepolymer into a solution with the mass concentration of 5-15% by using an ethanol-water solvent, dipping a carbon fiber woven fabric, a carbon felt or a carbon paper into the solution of the prepolymer, then placing the solution in a vacuum drying oven to remove the solvent, placing the dipped material between two layers of polytetrafluoroethylene sheets, carrying out hot pressing for 10-20 min at the temperature of 220-230 ℃ and the mould pressing pressure of 1-2 MPa, cooling and taking out to obtain a pre-cured sheet or plate; then placing the pre-cured sheet or plate between two layers of stainless steel sheets, putting the sheet or plate into a press, raising the pressure to 4-5 MPa, raising the temperature to 270-300 ℃ at a rate of 5-10 ℃/min, keeping the temperature for 3-5 min, and naturally cooling under the pressure to obtain the carbon fiber-resin composite sheet or plate; the carbon fiber-resin composite sheet or plate is carbonized and graphitized to obtain the carbon fiber-graphite composite material with excellent conductivity.
10. The method for preparing a composite material from a polycondensation type thermosetting resin prepolymer according to claim 8 or 9, wherein: the ethanol-water solvent is prepared by mixing ethanol and water according to the volume ratio of 2.5-1: 1.
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| CN115232272A (en) * | 2022-09-20 | 2022-10-25 | 西南林业大学 | Amino-terminated polymer-furfural thermosetting resin and application thereof |
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