A manufacturing process for rigid polyurethane foam insulation boards

Abstract

This application discloses a preparation process for rigid polyurethane foam insulation board, relating to the field of thermal insulation materials technology. The process includes preparing a rigid polyurethane foam core material and compositing the core material with a vacuum protective surface layer. The rigid polyurethane foam core material comprises, by weight, 100 parts polyether polyol, 1 part catalyst, 0.3 parts water, 1 part foam stabilizer, 3 parts expandable graphite-microsilica powder composite, and 5-30 parts SEBS modifier. The vacuum protective surface layer is an aluminum foil bag. The compositing of the core material with the vacuum protective surface layer specifically involves: placing the rigid polyurethane foam core material into an aluminum foil bag and vacuum sealing it to obtain the rigid polyurethane foam insulation board. This process achieves better thermal insulation and reduces material cracking or damage caused by changes in the external environment.

Description

Technical Field

[0001] This invention relates to the field of thermal insulation materials technology, and in particular to a preparation process for rigid polyurethane foam insulation boards. Background Technology

[0002] Vacuum insulation panels are a new type of thermal insulation material with excellent thermal insulation performance. In the field of cold chain transportation, they can greatly reduce the energy consumption problem caused by poor thermal insulation performance of insulation materials. Most existing vacuum insulation panels are composed of a core material and a vacuum protective surface layer. They effectively prevent heat transfer caused by air convection, thus achieving good thermal insulation effect. The core material commonly uses polyurethane foam as raw material. Rigid polyurethane foam contains a large number of closed micropores, with the size of the pores usually ranging from tens to hundreds of micrometers and being evenly distributed, effectively preventing gas convection and heat conduction.

[0003] For example, Chinese patent application number CN202211353093.7 describes a fully water-filled open-cell rigid polyurethane foam and its preparation method. The foam includes a mixture of polyether polyols and polymethylene polyphenyl polyisocyanate. It is reinforced by a synergistic system of expandable graphite and silane coupling agent modified microsilica powder. Using a xylene-assisted ultrasonic intercalation process, the interlayer spacing of expandable graphite sheets is increased, providing nanoscale confinement space for microsilica powder. The silane coupling agent (KH-550) forms a gradient graft layer on the surface of microsilica powder, realizing the chemical bond transition from inorganic core to organic shell. The steric hindrance effect of modified microsilica powder between graphite sheets and the Si-OC bond formed at the graphite / microsilica powder interface construct a three-dimensional stress transfer network, improving energy dissipation efficiency.

[0004] However, expandable graphite has a hydrophobic carbon layer on its surface (contact angle > 100°), while silane-modified microsilica powder has a polar Si-O-Si bond on its surface (contact angle < 30°). The thermodynamic incompatibility between the two leads to micron-level phase separation within the composite, resulting in decreased compressive strength, crack propagation paths in the cell walls, and ultimately reduced thermal insulation and mechanical strength. Summary of the Invention

[0005] This application provides a manufacturing process for rigid polyurethane foam insulation boards, which solves the problem of reduced insulation capacity caused by the separation of thermodynamically incompatible phases of graphite and silicon powder in the prior art, thus achieving stronger insulation capacity.

[0006] This application provides a manufacturing process for rigid polyurethane foam insulation boards, including the preparation of rigid polyurethane foam core material and the composite of the core material with a vacuum protective surface layer;

[0007] The rigid polyurethane foam core material comprises, by weight: 100 parts polyether polyol, 1 part catalyst, 0.3 parts water, 1 part foam stabilizer, 3 parts expandable graphite-microsilica composite, and 5-30 parts SEBS modifier.

[0008] The SEBS modifier is a styrene-ethylene-butene-styrene triblock copolymer. The SEBS modifier is SEBS particles modified with ionic liquid (IL). The ionic liquid (IL) is 1-butyl-3-methylimidazolium hexafluorophosphate, and the amount added is 0.5-3 parts by weight.

[0009] The vacuum protective layer is an aluminum foil bag;

[0010] The core material and vacuum protective surface layer are composited as follows: rigid polyurethane foam core material is placed in an aluminum foil bag and vacuum sealed to obtain rigid polyurethane foam insulation board.

[0011] Furthermore, the polyether polyol is a rigid polyether polyol with a hydroxyl value between 360-390 mgKOH / g using glycerol as an initiator, a rigid polyether polyol with a hydroxyl value between 400-600 mgKOH / g using sorbitol as an initiator, and a rigid polyether polyol with a hydroxyl value between 250-500 mgKOH / g using propylene glycol as an initiator, and the weight ratio of the three is 1:1:1.

[0012] Furthermore, the preparation method of the expandable graphite-microsilica composite is as follows:

[0013] Expandable graphite was placed in xylene, ultrasonically dispersed, and then silica powder was added. The mixture was stirred evenly, the solids were filtered and washed, and the composite was dried to obtain the composite material. The weight ratio of expandable graphite to silica powder was 1:0.3.

[0014] Furthermore, the catalyst is a mixture of triethanolamine and dibutyltin dilaurate; the weight ratio of triethanolamine to dibutyltin dilaurate is 1:1.

[0015] Furthermore, the process of ionic liquid (IL) modified SEBS particles is as follows: the ionic liquid is heated to 80°C, and after the viscosity is less than 50 mPa·s, it is injected into SEBS that has been pre-melted at 180°C at a weight ratio of IL / SEBS = 10%. The mixture is maintained at a shear rate of 600-800 rpm for 5 min, and then crosslinked at 190°C and 0.5 MPa for 15 min. Finally, it is cooled by liquid nitrogen at -20°C at a cooling rate greater than 50°C, and granulation is performed to obtain IL modified SEBS particles of 1-2 mm.

[0016] Furthermore, the polyether polyols include combinations of different polyether polyols with NCO values ​​of 1%, 1.2%, and 1.4% in a volume ratio of 3:5:2.

[0017] Furthermore, the preparation method of rigid polyurethane foam core material is as follows:

[0018] S1. Dry SEBS particles under vacuum at 80℃ for 4 hours, then premix them with various polyether polyols at a mass ratio of 1:3, and melt-blend them at 180-200℃ under nitrogen protection for 15 minutes.

[0019] S2. Mix the pretreated SEBS / polyether mixture with the remaining polyether polyols, catalyst, water, and foam stabilizer at 70°C for 10 min (1000 rpm).

[0020] S3. After mixing, let stand for 2 hours in an environment of 50℃ and relative humidity <30%;

[0021] S4. Add expandable graphite-silica powder composite and disperse at high speed at 1500 rpm and 75℃ for 10 min;

[0022] S5 is mixed with diphenylmethane diisocyanate (MDI) at a ratio of 1:1.4, then injected into a mold, and foamed and cured at 45°C and 0.5MPa pressure for 30 minutes. After curing, it is cut to obtain rigid polyurethane foam core material.

[0023] Furthermore, polyether polyols include flexible matrix groups and rigid reinforcement groups.

[0024] Furthermore, the rigid reinforcement group is a combination of medium NCO polyether and high NCO polyether; the flexible matrix group is a combination of low NCO polyether and IL-pretreated SEBS.

[0025] Furthermore, in step S1, after mixing the flexible matrix group, the rigid reinforcement group is added and mixing continues.

[0026] One or more technical solutions provided in the embodiments of this application have at least the following technical effects or advantages:

[0027] Firstly, the styrene and ethylene-butene segments in the SEBS block copolymer can improve interfacial compatibility and enhance interfacial thermal stability; the interfacial shear strength is improved through the π-π interaction and hydrogen bond network of SEBS, and the fracture toughness is optimized through the SEBS nanofiber network.

[0028] Secondly, ionic liquid-modified SEBS achieves cross-scale synergy through a multi-level dynamic bonding network. π-cation bonds provide high-strength anchoring and inhibit interfacial debonding; dynamic cross-linking of ion clusters dissipates strain energy and improves fatigue life; gradient buffer layer and through-network work together to deflect cracks.

[0029] Thirdly, through the synergistic effect of polyether polyols with multi-level NCO values ​​and IL interface regulation, polarity matching and energy dissipation are achieved through multi-scale interactions such as chemical bonds (covalent / ionic-dipole), hydrogen bond networks, and molecular chain orientation.

[0030] Fourth, the flexible matrix reacts preferentially during low-speed mixing at 40℃ to form a flexible continuous phase network: the EB segment of SEBS and the low-NCO polyether form an interpenetrating network through hydrogen bonds, forming an energy dissipation framework; the imidazole cation of IL forms a dynamic ion-dipole bond with the oxygen atom (-O-) of the polyether, providing pre-crosslinking points; the flexible phase accounts for 60%-70%, covering the surface of graphite particles to form a 5-10nm buffer layer; the rigid reinforcement group (medium / high NCO polyether) is dispersed under high-speed shear at 400rpm: the high-NCO polyether preferentially reacts with the hydroxyl groups on the graphite surface to form covalent bonds; the medium-NCO polyether forms an interfacial hydrogen bond network (bond density increases by 50%) with the unreacted -OH in the flexible phase through -NCO, bridging the two phases. Detailed Implementation

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to limit the invention; the term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0032] Example 1: A process for preparing a rigid polyurethane foam insulation board, including preparing a rigid polyurethane foam core material and compositing the core material with a vacuum protective surface layer.

[0033] The rigid polyurethane foam core material comprises, by weight: 100 parts of various polyether polyols, 1 part of catalyst, 0.3 parts of water, 1 part of foam stabilizer, 3 parts of expandable graphite-microsilica composite, and 5-30 parts of SEBS modifier.

[0034] The various polyether polyols are rigid polyether polyols with hydroxyl values ​​between 360-390 mgKOH / g and glycerol as the initiator, rigid polyether polyols with hydroxyl values ​​between 400-600 mgKOH / g and sorbitol as the initiator, and rigid polyether polyols with hydroxyl values ​​between 250-500 mgKOH / g and propylene glycol as the initiator, and the weight ratio of the three is 1:1:1;

[0035] The preparation method of the expandable graphite-silica powder composite is as follows: expandable graphite is placed in xylene, ultrasonically dispersed, silica powder is added, mixed evenly, the solid matter is filtered and washed, and dried to obtain the composite. The weight ratio of expandable graphite to silica powder is 1:0.3.

[0036] The silica powder was pretreated by adding water, ultrasonically dispersing it, adding silane coupling agent KH-550, mixing it evenly, filtering, washing, and drying it to obtain pretreated silica powder.

[0037] The catalyst is a mixture of triethanolamine and dibutyltin dilaurate; the weight ratio of triethanolamine to dibutyltin dilaurate is 1:1.

[0038] The SEBS modifier is a commonly used styrene-ethylene-butene-styrene triblock copolymer; in this example, YH-503T from Sinopec Hunan Petrochemical Co., Ltd. was selected.

[0039] The preparation method of rigid polyurethane foam core material is as follows:

[0040] S1. Dry SEBS particles under vacuum at 80℃ for 4 hours, then premix them with various polyether polyols at a mass ratio of 1:3, and melt-blend them at 180-200℃ under nitrogen protection for 15 minutes.

[0041] S2. Mix the pretreated SEBS / polyether mixture with the remaining polyether polyols, catalyst, water, and foam stabilizer at 70°C for 10 min (1000 rpm).

[0042] S3. After mixing, let stand for 2 hours in an environment of 50℃ and relative humidity <30%;

[0043] S4. Add expandable graphite-silica powder composite and disperse at high speed at 1500 rpm and 75℃ for 10 min;

[0044] S5 is mixed with diphenylmethane diisocyanate (MDI) at a ratio of 1:1.4, then injected into a mold, and foamed and cured at 45°C and 0.5MPa pressure for 30 minutes. After curing, it is cut to obtain rigid polyurethane foam core material.

[0045] The vacuum protective layer is a commonly used aluminum foil bag. In this embodiment, an aluminum foil bag with a thickness of 0.12mm is selected from Kunshan Tonglida Packaging Materials Co., Ltd.

[0046] The core material and vacuum protective surface layer are composited as follows: rigid polyurethane foam core material is placed in an aluminum foil bag and vacuum sealed to obtain rigid polyurethane foam insulation board.

[0047] The technical solutions described in the embodiments of this application have at least the following technical effects or advantages:

[0048] SEBS block copolymers, including styrene and ethylene-butene segments, can improve interfacial compatibility and enhance interfacial thermal stability. Through the π-π interaction and hydrogen bond network of SEBS, the interfacial shear strength is improved, and the fracture toughness is optimized through the SEBS nanofiber network.

[0049] The p orbitals (ionization energy ≈ 9.2 eV) of the benzene ring in the styrene segment (PS) are similar to those in graphite sp orbitals. 2 π of hybrid carbon * Orbitals (electron affinity ≈ 4.3 eV) form charge-transfer complexes; the slip barrier generated by π-π stacking is lowered;

[0050] The CH bond (bond energy 413 kJ / mol) of the butene chain in the ethylene-butene segment (EB) forms a dipole-induced effect with the NH bond (bond energy 391 kJ / mol) of the urethane in the polyurethane rigid segment;

[0051] The PS segment forms a 2-3 nm thick adsorption layer on the graphite surface, and the EB segment extends into the polyurethane matrix to form a gradient transition region.

[0052] The PS / EB interface forms nanoscale "anchor points" (spacing approximately 20 nm); PS micro-regions (size 15-25 nm) serve as physical cross-linking points, and the EB continuous phase forms energy dissipation channels. Through micro-phase separation and regulation, not only is the interfacial bonding ability increased, but the possibility of crack generation and growth is also reduced. Furthermore, the energy dissipation channels formed can reduce energy conduction, reduce heat transfer, and increase heat preservation capacity.

[0053] When the crack propagates and encounters the PS microregion, it is deflected. The EB phase absorbs energy through molecular chain slippage, which increases the toughness of the interface and prevents the interface from peeling off, thus preventing the insulation board from failing.

[0054] The mechanism of action of SEBS block copolymer was verified by comparative experiments, and the performance of rigid polyurethane foam was tested. The test methods are shown in Table 1, the results are shown in Table 2, and the key interface characterization data are shown in Table 3.

[0055] Table 1

[0056]

[0057]

[0058] Table 2

[0059]

[0060] Table 3

[0061]

[0062] Example 2: The above example achieved dual anchoring of interface chemistry and physics by adding SEBS modifier, synergistic energy dissipation of crack deflection and molecular chain slip, and decoupling of intercalation pre-setting and foaming process. However, in this application, it is used in refrigerated trucks, mainly for transportation. Under different environments, the temperature changes greatly, and there is a difference in the coefficient of thermal expansion between SEBS (CTE = 180ppm / ℃) and polyurethane matrix (CTE = 80ppm / ℃). Experiments showed that 0.8% interfacial strain (DIC measurement) was generated in a 48h cycle of -20℃ to 60℃. Therefore, further improvements were made based on Example 1.

[0063] SEBS modifiers are also pretreated with ionic liquids (ILs). The pretreatment process is as follows: the ionic liquid is heated to 80°C and the viscosity is less than 50 mPa·s. Then, it is injected into SEBS that has been pre-melted at 180°C at a weight ratio of IL / SEBS = 10%. The mixture is maintained at a shear rate of 600-800 rpm for 5 minutes. Then, it is crosslinked at 190°C and 0.5 MPa for 15 minutes. Finally, it is cooled by liquid nitrogen at -20°C at a cooling rate greater than 50°C. The final granulation yields IL-modified SEBS particles of 1-2 mm.

[0064] In this embodiment, the ionic liquid (IL) used is 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]), and the amount added is 0.5-3 parts by weight.

[0065] The technical solutions described in the embodiments of this application have at least the following technical effects or advantages:

[0066] Ionic liquid-modified SEBS achieves cross-scale synergy through a multi-level dynamic bonding network. π-cation bonds provide high-strength anchoring and inhibit interfacial debonding; dynamic cross-linking of ion clusters dissipates strain energy and improves fatigue life; gradient buffer layer and through-network work together to deflect cracks.

[0067] The coupling effect of π-cation electron clouds, imidazole cations ([BMIM)) + The positive charge center of the electrons forms an electrostatic-π interaction with the π electron cloud of the benzene ring in the styrene (PS) segment of the SEBS; the interaction energy is approximately 0.5-0.8 eV (between hydrogen bonds and covalent bonds);

[0068] Anion-flexible chain dipole interaction, ionic liquid anion (PF6) - The strong polarity of PF6 induces dipole interactions with the CH bond dipole formation of the ethylene-butene (EB) segment of SEBS; each PF6 - The binding energy with the EB segment is approximately 5-10 kJ / mol; PF6... -It can slide along the EB chain segment (activation energy approximately 20 kJ / mol), achieving dynamic stress release.

[0069] Every 3-5 [BMIM][PF6] molecules form a 2-4 nm ion cluster through cation-anion stacking; the ion cluster is anchored to the benzene ring in the PS segment by electrostatic interaction, and simultaneously through PF6 - Transphase connections are formed through dipole interactions with EB segments; ionic clusters act as dynamic crosslinking points and can reversibly dissociate under strain; crack propagation requires the simultaneous destruction of π-cation bonds and ionic clusters (J integral changes from 28 to 42 kJ / m). 2 This greatly increases the energy required for crack propagation.

[0070] A 5-10 nm thick ionic liquid enrichment layer is formed on the surface of the PS micro-region; the proportion of π-cation bonds between imidazole cations and benzene rings in the enrichment layer is >70% (Raman imaging statistics); thermal stress is transferred through the gradient of the enrichment layer, and the crack propagation path is deflected by 55-70° in the enrichment layer, reducing the degree of crack propagation and establishing a stress buffer layer.

[0071] Ion clusters and SEBS segments form a three-dimensional through-network; during temperature cycling, ion clusters dissociate and absorb energy, and strain energy is dissipated through ion slip and segment motion in synergy. By utilizing a dynamic energy dissipation network, stress accumulation is reduced.

[0072] The mechanism of action of IL was verified by experiments, and the final results were verified by experiments based on Experiment 2. The results and test standards are shown in Table 4.

[0073] Table 4

[0074]

[0075]

[0076] Example 3: Example 2 achieved cross-scale synergy through multi-level dynamic bonding network by modifying SEBS with ionic liquid. π-cation bonds provide high-strength anchoring and inhibit interface debonding; dynamic cross-linking of ionic clusters dissipates strain energy and improves fatigue life; gradient buffer layer and through-network work together to deflect cracks. However, the mixing of multiple components often leads to polarity mismatch. The solubility difference between IL-modified SEBS and polyether polyol expandable graphite is not small, which easily leads to local thermodynamic incompatibility. Therefore, further improvements were made based on Example 2.

[0077] By controlling the amount of isocyanate, polyether polyols with different NCO values ​​(molar ratio of NCO groups to hydroxyl groups) were obtained. The specific amount of diphenylmethane diisocyanate was obtained by calculation.

[0078] The calculation process is as follows:

[0079]

[0080] Each 100g of diphenylmethane diisocyanate contains 0.8mol NCO; the amount of diphenylmethane diisocyanate used can be calculated.

[0081] A mixture of various polyether polyols, including polyether polyols with NCO values ​​of 1%, 1.2%, and 1.4%, is used in a volume ratio of 3:5:2.

[0082] The technical solutions described in the embodiments of this application have at least the following technical effects or advantages:

[0083] Through the synergistic effect of polyether polyols with multi-level NCO values ​​and IL interface regulation, polarity matching and energy dissipation are achieved through multi-scale interactions such as chemical bonds (covalent / ionic-dipole), hydrogen bond networks, and molecular chain orientation.

[0084] Low NCO polyether (δ=20MPa) 1 / 2 It is compatible with SEBS (δ=18), and the high NCO polyether (δ=22) bonds with graphite (δ=16) to form a polar gradient interface. The low NCO component (1%) preferentially reacts with SEBS to form a flexible network, while the high NCO component (1.2%) bonds with graphite in the later stage. The -NCO of the medium NCO component (1.4%) polyether reacts with the -OH of graphite to form chemical bonds (bond energy 0.5eV), which offsets the polarity difference. At low temperature, the low NCO component reacts to form a continuous phase, while at high temperature, the high NCO component rapidly crosslinks and locks the graphite dispersion. The low NCO component forms hydrogen bonds (bond energy 25kJ / mol), and the medium and high NCO components construct a covalent network. The multi-level bonds work together to consume energy.

[0085] In polyether polyols with low NCO values, each polyether molecule contains one -NCO group, which preferentially reacts with the secondary amine group (-NH) of SEBS to form flexible urethane bonds (bond energy ≈350kJ / mol) to encapsulate graphite particles; in polyether polyols with high NCO values, the excess -NCO can react with the hydroxyl groups (-OH) on the graphite surface to form covalent bonds (COC bond energy ≈460kJ / mol), enhancing interfacial bonding and inhibiting aggregation;

[0086] Unreacted -OH groups form hydrogen bonds with the ether bonds (-O-) of SEBS (bond energy ≈ 25 kJ / mol), increasing interfacial toughness. Excess -NCO groups form intramolecular hydrogen bonds (NH···OC, bond length ≈ 2.0) with the ether oxygen atoms of the polyether backbone. This process increases the crosslinking density, ultimately resulting in a multi-scale crosslinking network, including: SEBS-NH forming main valence bonds with polyether-NCO to form a continuous phase framework; polyether-NCO forming interfacial bonds with graphite-OH to enhance stress transfer efficiency; and intermolecular hydrogen bonds in polyether dissipating energy and improving dynamic fatigue performance.

[0087] The mechanism of action and results of different NCO polyether polyols were verified by experimental design. The experimental groups are shown in Table 5 and the results are shown in Table 6.

[0088] Table 5

[0089]

[0090]

[0091] Table 6

[0092]

[0093] Excess -NCO and IL anions (such as PF6) - The formation of ion-dipole interactions determines the interfacial binding energy and reactivity; the orientation of SEBS segments and the distribution of hydrogen bond networks control dynamic modulus fluctuations and energy dissipation efficiency; and the dispersion of graphite sheets and the phase interface gradient affect the continuity of the thermal conduction pathway.

[0094] Alternatively, various materials can be dissolved in tetrahydrofuran in step S1 to achieve dispersion in a simpler environment (30°C, 300 rpm, 30 min). THF can be volatilized under reduced pressure by gradually heating to 50°C (heating rate 2°C / min) at a rate of 0.5 mL / min, maintaining the H2O content gradient (10→30%). This allows the polarity difference between the hard and soft segments in the polyurethane to form an ordered interface through phase separation. Under a shear rate of 750 rpm, the dissociation of hyperbranched molecular chain entanglements is promoted, forming nanochannels along the shear direction. A vertical electric field of 2 kV / mm is applied externally to induce dipole orientation. Because the soft segments are derived from polyether polyols and the hard segments from diphenylmethane diisocyanate (MDI), the production of nanochannels is maximized when the mass ratio of polyether polyol to MDI is 1:1. This restricts the free path of gas molecule movement (from micrometer to nanometer scale), and the molecular chains at the nanochannel interface are highly ordered (SAXS shows an orientation degree > 85%). The mean free path of phonons decreases from 50 nm to 20 nm. The inner walls of the nanochannels are composed of soft segments, which prevent water molecule penetration. After hygrothermal aging, the closed-porosity remains > 90%, restricting gas molecule movement and enhancing phonon scattering. The hard segments self-assemble to form a nano-reinforcing phase, and crack propagation requires bypassing the ordered structure.

[0095] Example 4: Example 3 solved the problem of polarity mismatch in multi-component mixing by using a combination of polyether polyols with different NCO values ​​or by self-assembly of nanochannels. To further optimize the process for practical applications, further improvements were made based on Example 3.

[0096] Polyether polyols were grouped, including flexible matrix group: low NCO polyether + IL pretreated SEBS;

[0097] Rigid reinforcement group: medium NCO polyether + high NCO polyether;

[0098] After mixing the flexible matrix group in S1 (40℃, 200rpm, 20min), add the rigid reinforcement group and continue mixing (400rpm, 20min).

[0099] The technical solutions described in the embodiments of this application have at least the following technical effects or advantages:

[0100] The flexible matrix reacts preferentially during low-speed mixing at 40℃, forming a flexible continuous phase network: the EB segment of SEBS and the low-NCO polyether form an interpenetrating network through hydrogen bonds, forming an energy dissipation framework; the imidazole cation of IL forms dynamic ion-dipole bonds with the oxygen atoms (-O-) of the polyether, providing pre-crosslinking points; the flexible phase accounts for 60%-70%, covering the surface of graphite particles to form a 5-10nm buffer layer; the rigid reinforcement group (medium / high NCO polyether) is dispersed under high-speed shear at 400rpm: the high-NCO polyether preferentially reacts with the hydroxyl groups on the graphite surface to form covalent bonds; the medium-NCO polyether forms an interfacial hydrogen bond network (bond density increases by 50%) with the unreacted -OH in the flexible phase through -NCO, bridging the two phases.

[0101] The IL-SEBS / low NCO polyether system forms a nanofiber network, dissipating energy through molecular chain slippage; the medium / high NCO polyether crosslinks form 100-200nm island structures, which are covalently anchored at the interface between the two phases on the flexible network nodes, forming a 10-30nm gradient region, with the NCO content gradually changing from 0.8% to 1.2%; matching memory differences.

[0102] IL anion (PF6) - The excess -NCO in the rigid phase forms ionic-dipole bonds, which can be reversibly dissociated under strain; the PS microregions of SEBS and the high-NCO polyether form physical crosslinking points through π-π stacking; the hydrogen bond network (bond energy 25kJ / mol) and covalent bonds (350-460kJ / mol) form multi-level energy dissipation pathways.

[0103] The performance of the core material prepared in Example 4 was tested; the results are shown in Table 7.

[0104] Table 7

[0105]

[0106] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A process for the production of rigid polyurethane foam insulation boards, characterized in that, The application relates to a preparation method of a hard-foam polyurethane core material and a core material and a vacuum protective surface layer. The hard-foam polyurethane core material comprises, by weight, 100 parts of polyether polyol, 1 part of a catalyst, 0.3 parts of water, 1 part of a foam stabilizer, 3 parts of an expandable graphite-microsilica powder compound and 5-30 parts of SEBS modifier. The SEBS modifier is a styrene-ethylene-butylene-styrene triblock copolymer, the SEBS modifier is SEBS particles modified by an ionic liquid, the ionic liquid is 1-butyl-3-methylimidazolium hexafluorophosphate, and the addition amount of the ionic liquid is 0.5-3 parts by weight. The polyether polyol comprises different polyether polyols with NCO values of 1%, 1.2% and 1.4% in a volume ratio of 3:5:2; the NCO value is the molar ratio of NCO groups to hydroxyl groups in the polyether polyol, and the NCO value = the number of NCO groups moles / the number of hydroxyl groups moles. The vacuum protective surface layer is an aluminum foil bag. The core material is combined with the vacuum protective surface layer in the following manner: the hard-foam polyurethane core material is put into the aluminum foil bag and vacuum packaged to obtain the hard-foam polyurethane insulation board.

2. A process for the preparation of rigid polyurethane foam board as claimed in claim 1, wherein, The polyether polyol is a rigid polyether polyol with a glycerol starting agent and a hydroxyl value of 360-390 mgKOH / g, a rigid polyether polyol with a sorbitol starting agent and a hydroxyl value of 400-600 mgKOH / g, and a rigid polyether polyol with a propylene glycol starting agent and a hydroxyl value of 250-500 mgKOH / g, and the weight ratio of the three is 1:1:

1.

3. The process for preparing a rigid polyurethane foam board according to claim 1, wherein the blowing agent is used in an amount of 0.1 to 0.5 parts by weight based on 100 parts by weight of the polyol. The preparation method of the expandable graphite-microsilica powder compound is as follows: The expandable graphite is put into dimethylbenzene, ultrasonically dispersed, the microsilica powder is added, mixed uniformly, the solid is filtered and washed, and the compound is obtained after drying; the weight ratio of the expandable graphite to the microsilica powder is 1:0.

3.

4. The process for preparing a rigid polyurethane foam board according to claim 1, wherein the blowing agent is used in an amount of 0.1 to 0.5 parts by weight based on 100 parts by weight of the polyol. The catalyst is a mixture of triethanolamine and dibutyltin dilaurate; the weight ratio of the triethanolamine to the dibutyltin dilaurate is 1:

1.

5. The process for preparing a rigid polyurethane foam board according to claim 1, wherein the blowing agent is used in an amount of 0.1 to 0.5 parts by weight based on 100 parts by weight of the polyol. The process of the SEBS particles modified by the ionic liquid is as follows: the ionic liquid is heated to 80 DEG C, and after the viscosity is less than 50 mPa.s, the SEBS is injected into the SEBS which has been melted in advance at 180 DEG C according to the weight ratio of the ionic liquid / SEBS=10%, the shearing rate is 600-800 rpm, and the shearing is maintained for 5 min; then the crosslinking is carried out at 190 DEG C and 0.5 MPa for 15 min; then the cooling is carried out through liquid nitrogen at-20 DEG C, the cooling rate is greater than 50 DEG C, and finally the SEBS particles modified by the ionic liquid are obtained by granulation.

6. The process for preparing a rigid polyurethane foam board according to claim 1, wherein the blowing agent is used in an amount of 0.1 to 0.5 parts by weight based on 100 parts by weight of the polyol. The preparation method of the hard-foam polyurethane core material is as follows: S1, the SEBS particles are vacuum dried at 80 DEG C for 4 h, then pre-mixed with the polyether polyols according to the mass ratio of 1:3, and then melt-blended at 180-200 DEG C under the protection of nitrogen for 15 min; S2, the pretreated SEBS / polyether mixture is mixed with the remaining polyether polyols, the catalyst, the water and the foam stabilizer at 70 DEG C and 1000 rpm for 10 min; S3, after the mixing, the mixture is placed in an environment with a temperature of 50 DEG C and a relative humidity of less than 30% for 2 h; S4, the expandable graphite-microsilica powder compound is added and high-speed dispersed at 1500 rpm and 75 DEG C for 10 min; S5, mixed with diphenyl methane diisocyanate at a ratio of 1:1.4, then injected into a mold, foamed and cured at 45℃ under a pressure of 0.5MPa for 30min, cut after aging to obtain a rigid polyurethane foam core material.

7. A process for the production of rigid polyurethane foam boards according to claim 6, characterized in that, The polyether polyols include a flexible matrix group and a rigid reinforcing group.

8. A process for the production of rigid polyurethane foam boards according to claim 7, characterized in that, The rigid reinforcing group is a combination of polyether with an NCO value of 1.2% and polyether with an NCO value of 1.4%; the flexible matrix group is a combination of polyether with an NCO value of 1% and SEBS pretreated with ionic liquid.

9. A process for the production of rigid polyurethane foam boards according to claim 8, characterized in that, The rigid reinforcing group is added after the flexible matrix group is mixed in step S1 and the mixing is continued.

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