A new building thermal insulation anticorrosion material and a preparation method thereof

Abstract

The application discloses a novel building thermal insulation and corrosion prevention material and a preparation method thereof, relates to the technical field of building thermal insulation and corrosion prevention materials, and sequentially comprises a self-diagnosis and self-repairing double-effect corrosion prevention bottom layer, a gradient modulus thermal stress buffer transition layer and a closed-cell hydrophobic aramid fiber reinforced aerogel-polyimide composite thermal insulation layer from a metal base material outward. Mesoporous silica microcapsules in the corrosion prevention bottom layer load a color developing agent and an inhibitor, can visually and early warn in-situ corrosion and synchronously release the inhibitor, the elastic modulus of the transition layer continuously and gradually changes along the thickness direction to buffer the interface thermal stress, and the thermal insulation layer realizes the synergy of thermal insulation, strength and low water absorption performance through in-situ grafting of aerogel and aramid fiber reinforcement. The application is used for thermal insulation and corrosion prevention integrated treatment of building and industrial pipe network metal structural members.

Description

Technical Field

[0001] This invention relates to the field of building insulation and anti-corrosion materials technology, specifically to a novel building insulation and anti-corrosion material and its preparation method. Background Technology

[0002] Currently, metal structural components in the building and petrochemical pipeline network fields generally adopt a technology that combines anti-corrosion and insulation layers. This involves coating the metal substrate with an epoxy zinc-rich anti-corrosion primer, then covering it with a polyurethane foam insulation layer, and finally encasing it in a metal or non-metal protective shell. The joints are sealed with adhesive tape. The epoxy zinc-rich anti-corrosion primer is typically 60 to 80 micrometers thick, and the polyurethane foam insulation layer is typically 30 to 50 millimeters thick. The outer shell is fixed to the insulation layer using self-tapping screws or clamps. In this existing technology, the anti-corrosion primer and insulation layer are independent functional units, simply superimposed through physical bonding or mechanical connection, lacking functional coupling. When the insulation layer ages or breaks, allowing moisture and salt to seep in, corrosion on the metal substrate surface is difficult to detect in time because it is masked by the insulation layer. Current technology lacks in-situ visual early warning methods, typically requiring periodic removal of the insulation layer for manual inspection to detect corrosion. The materials often suffer from severe thinning or even perforation. In addition, there is a significant difference in the coefficient of thermal expansion between the anti-corrosion primer and the insulation layer. For a long time, the technical approach used in this field has been to design the anti-corrosion layer and the insulation layer independently and simply physically overlap them. The technology has not been recognized that functional coupling and active buffering of thermal stress can be achieved through interlayer chemical cross-linking and gradient modulus transition. This application breaks through this design inertia and achieves chemical cross-linking coupling of the three-layer structure through interface activation and semi-interpenetrating network gradient curing. Under the wide temperature range of thermal cycling conditions from -40 degrees Celsius to 150 degrees Celsius, stress concentration is easily generated at the interface. After long-term repeated action, coating cracks and interface delamination occur. At the same time, aerogel materials themselves are mechanically brittle and their surface is rich in hydrophilic hydroxyl groups. If they are composited into conventional insulation substrates by physical doping, it is difficult to take into account the insulation performance, mechanical strength and moisture resistance, which restricts their promotion and application in the field of building insulation and anti-corrosion. Therefore, we propose a new building insulation and anti-corrosion material and its preparation method. Summary of the Invention

[0003] The purpose of this invention is to provide a novel building insulation and corrosion protection material and its preparation method.

[0004] The technical problems to be solved by this invention include: First, the corrosion in existing thermal insulation and anti-corrosion composite structures is highly concealed and lacks early in-situ detection methods, resulting in delayed corrosion detection and irreversible damage. Second, the thermal expansion coefficients between the anti-corrosion bottom layer and the thermal insulation outer layer are mismatched, resulting in interfacial thermal stress concentration under wide temperature range thermal cycling conditions, which in turn leads to coating cracks and delamination of the thermal insulation layer. Third, aerogel materials have high intrinsic mechanical brittleness and are prone to moisture absorption failure on the surface, making it difficult to simultaneously achieve high thermal insulation, high strength and low water absorption performance.

[0005] To address the aforementioned technical problems, this invention provides a novel building insulation and anti-corrosion material, comprising a metal substrate and, sequentially stacked from the metal substrate, a self-diagnostic and self-healing dual-effect anti-corrosion underlayer, a gradient modulus thermal stress buffer transition layer, and a closed-cell hydrophobic aramid fiber reinforced aerogel-polyimide composite insulation layer. The self-diagnostic and self-healing dual-effect anti-corrosion underlayer includes an epoxy resin matrix and mesoporous silica microcapsules dispersed within the epoxy resin matrix. The mesoporous silica microcapsules are loaded with a colorant and a corrosion inhibitor. The microcapsule shell ruptures responsively due to ion concentration changes caused by localized corrosion of the metal substrate, achieving non-destructive in-situ self-repair of corrosion. Diagnosis and synchronous self-healing: The gradient modulus thermal stress buffer transition layer is formed by a semi-interpenetrating network composed of epoxy resin and polysiloxane components. The elastic modulus changes continuously along the thickness direction, with a higher modulus near the anti-corrosion bottom layer and a lower modulus near the insulation layer. This disperses and buffers the concentrated thermal stress at the interface within the thickness direction of the transition layer. The closed-cell hydrophobic aramid fiber reinforced aerogel-polyimide composite insulation layer includes a polyimide foam skeleton, hydrophobic modified aerogel particles grafted and crosslinked in situ on the surface of the pore walls of the polyimide foam skeleton, and a three-dimensional aramid fiber network distributed inside the polyimide foam skeleton. The pores are in a closed-cell structure.

[0006] This invention also provides a method for preparing the above-mentioned novel building thermal insulation and anti-corrosion material, which includes the following steps in sequence: surface pretreatment of metal substrate, preparation and dispersion of microcapsules, coating and curing of anti-corrosion underlayer, interlayer interface activation treatment, coating and curing of gradient transition layer, surface modification of aerogel, composite foaming molding, and bonding and curing of composite insulation layer and transition layer, so that the three-layer structure achieves integrated functional coupling through chemical cross-linking and interface activation treatment;

[0007] Compared with the prior art, the beneficial effects of the present invention by adopting the above technical solution are as follows:

[0008] 1. This invention utilizes the dual functions of ion-responsive color development and corrosion inhibition of mesoporous silica microcapsules to transform corrosion detection from post-event manual inspection relying on the removal of the insulation layer to real-time visual in-situ early warning, shortening the corrosion detection cycle and simultaneously inhibiting corrosion spread.

[0009] 2. The present invention uses a gradient modulus transition layer with a continuously varying thickness to disperse the thermal stress concentrated at the interface into the interior of the transition layer, thereby improving the interfacial bonding stability of the material under wide temperature range thermal cycling conditions and reducing the risk of coating cracking and delamination.

[0010] 3. This invention utilizes the synergistic effect of in-situ chemical grafting of aerogel and reinforcement with three-dimensional aramid fibers to maintain the low thermal conductivity of the composite insulation layer while improving its compressive and impact strength, and controlling the water absorption rate at a low level, thereby blocking the path of water penetration and corrosion-induced corrosion, and achieving long-term integration of thermal insulation and corrosion protection performance. Attached Figure Description

[0011] Figure 1 This is a schematic flowchart of the overall material layer structure in an embodiment of the present invention;

[0012] Figure 2 This is a schematic flowchart of the complete material preparation process in an embodiment of the present invention;

[0013] Figure 3 This is a schematic flowchart illustrating the self-diagnosis and self-repair process of the anti-corrosion substrate in an embodiment of the present invention. Detailed Implementation

[0014] The following is in conjunction with the appendix Figure 1-3 The specific embodiments of the present invention will be further described below. It should be noted that the description of these embodiments is for the purpose of helping to understand the present invention, but does not constitute a limitation of the present invention.

[0015] Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0016] I. Overall layered structure of the material:

[0017] The novel building insulation and anti-corrosion material of this invention comprises, from bottom to top along the thickness direction: a first layer is a metal substrate, which can be a building steel structure or an industrial pipeline body; a second layer is a self-diagnostic and self-healing dual-effect anti-corrosion underlayer, in which a large number of mesoporous silica microcapsule particles are uniformly dispersed in an epoxy resin continuous phase matrix, and colorants and corrosion inhibitors are loaded in a partitioned manner inside the microcapsules; a third layer is a gradient modulus thermal stress buffer transition layer, which is formed by a semi-interpenetrating network composed of polysiloxane components and epoxy resin components, adjacent to the anti-corrosion underlayer. The first side is a region with high cross-linking density, high modulus, and strong adhesion, while the side adjacent to the insulation layer is a region with low cross-linking density, high flexibility, and low modulus. The two are smoothly connected by a gradient transition region. The fourth layer is a closed-cell hydrophobic aramid fiber reinforced aerogel-polyimide composite insulation layer. This layer has a three-dimensionally interwoven aramid fiber network and hydrophobic modified aerogel particles grafted and cross-linked in situ onto the pore walls of the polyimide foam skeleton. The pores are presented in a closed-cell form. Each layer is laminated in sequence, and the layers are combined through chemical cross-linking and mechanical interlocking.

[0018] In this embodiment, the thickness of the self-diagnostic and self-healing dual-effect anti-corrosion substrate is controlled at 100 micrometers, the thickness of the gradient modulus thermal stress buffer transition layer is controlled at 120 micrometers, and the thickness of the closed-cell hydrophobic aramid fiber reinforced aerogel-polyimide composite insulation layer is controlled at 30 millimeters.

[0019] II. Working principle of the self-diagnostic and self-repairing dual-effect anti-corrosion substrate:

[0020] The microcapsules are uniformly dispersed in an epoxy resin matrix with an intact core-shell structure. The shell layer covers the color developer region and the corrosion inhibitor region. Initially, the surface of the metal substrate is in an uncorroded state. When micro-corrosion points appear on the local surface of the metal substrate, the local ion concentration changes due to the electrochemical corrosion reaction and iron ions are released. This chemical environment change is transmitted to the adjacent microcapsules, triggering local dissolution and rupture of the shell layer. After the microcapsules rupture, the corrosion inhibitor is released and migrates to the corrosion point to form a corrosion-inhibiting adsorption film to inhibit further corrosion spread. At the same time, after the color developer is released, it undergoes a complexation reaction with metal ions to form a visible discoloration area around the corrosion point, realizing non-destructive in-situ interpretation of the internal corrosion state by external visual or optical detection methods.

[0021] The colorimetric complexation reaction of the microcapsules can be described by the following stoichiometric relationship:

[0022] ;

[0023] In the formula, This indicates the iron ions released during the corrosion of the metal substrate, and their valence values ​​are either divalent or trivalent. This refers to the chromogenic ligand molecules released from the microcapsules, in this embodiment. It is a phenanthroline, This indicates the number of ligand molecules complexed with each metal ion. The generated metal complex has a characteristic color. The formation of this complex causes the area around the corrosion point to appear in a color different from the original color of the epoxy resin matrix, thereby achieving a self-diagnostic function. In this embodiment, benzotriazole is selected as the corrosion inhibitor. After its release, it can form an adsorption protective film on the metal surface to inhibit the further progress of the corrosion reaction. The average particle size of the microcapsule particles is controlled within the range of two to eight micrometers. Mesoporous silica is used as the wall material, and the color developer and corrosion inhibitor are released in a controlled manner through the pore structure.

[0024] III. Construction principle of gradient modulus thermal stress buffer transition layer:

[0025] The crosslinking density and elastic modulus of the transition layer show a smooth transition trend of monotonically decreasing along the thickness direction. The starting point, which corresponds to the side with a higher proportion of epoxy resin component, is marked as the high modulus region, and the ending point, which corresponds to the side with a higher proportion of polysiloxane component, is marked as the low modulus region. The middle is represented by a gradient area to show the continuous mixing ratio change of the two resin components along the thickness direction and the corresponding difference in crosslinking reaction rate.

[0026] The modulus distribution of this transition layer along its thickness can be approximated by the following exponential decay function:

[0027] ;

[0028] In the formula, This indicates the coordinate position in the thickness direction, measured from one side of the anti-corrosion base layer, with values ​​ranging from zero to the total thickness of the transition layer. Indicates position The elastic modulus of the material. This indicates the elastic modulus at the starting point immediately adjacent to the anti-corrosion substrate, i.e., the high modulus end. This indicates the elastic modulus at the point immediately adjacent to the end of the insulation layer, i.e., the low modulus end. This is the gradient control coefficient, and its value is determined by the ratio of epoxy resin to polysiloxane components and the programmed temperature curing process parameters. An increase in the value indicates a faster transition rate of the modulus along the thickness direction. A decrease in the value indicates a slower transition rate. In this embodiment, the curing temperature curve and the reactivity ratio of the two components are adjusted to achieve this. The value is stably controlled within the preset process window range to achieve a repeatable gradient modulus distribution. In this embodiment, the mass ratio of epoxy resin component to polysiloxane component changes continuously from 7:3 to 3:7 along the thickness direction.

[0029] IV. Microstructure of Closed-cell hydrophobic aramid fiber reinforced aerogel-polyimide composite insulation layer:

[0030] The polyimide foam skeleton is distributed in a three-dimensional continuous porous network. The surface of the pore walls is chemically grafted and in situ loaded with hydrophobic aerogel particles modified by silane coupling agent. The particle surface has hydrophobic groups. Aramid fibers are interwoven in a three-dimensional random way inside the foam skeleton to form a reinforcing network between the pore walls. The pore structure is presented in the form of closed pores, and there are no through channels between pores, thereby blocking the path of water penetration along the pores. In this embodiment, the hydrophobic modified aerogel particles account for 15% of the total mass of the composite insulation layer, and the aramid fibers account for 5% of the total mass of the composite insulation layer.

[0031] The water absorption rate of this composite insulation layer can be quantitatively evaluated using the following formula:

[0032] ;

[0033] In the formula, This indicates the water absorption rate of the composite insulation layer under standard immersion test conditions. This indicates the initial mass of the sample before immersion in water. The mass of the sample after immersion in water for a specified time according to standard methods is indicated. Through the design of a closed-cell hydrophobic structure, the water absorption rate of the composite insulation layer obtained in this embodiment can be controlled to below 2%, which is far lower than the water absorption level of traditional open-cell aerogel composite materials.

[0034] V. Preparation method:

[0035] The preparation method of the novel building insulation and anti-corrosion material in this embodiment includes the following:

[0036] The surface of the metal substrate is subjected to sandblasting and rust removal treatment and solvent degreasing and cleaning treatment in sequence to achieve the specified cleanliness and roughness level of the surface;

[0037] Mesoporous silica microcapsule wall material was prepared by sol-gel method. The color developer o-phenanthroline and the corrosion inhibitor benzotriazole were loaded into the mesoporous channels of the microcapsule by vacuum impregnation. Then, the prepared microcapsules were uniformly mixed into epoxy resin base material by ultrasonic dispersion process to form anti-corrosion base coating.

[0038] The above coating is uniformly applied to the pretreated metal substrate surface by spraying and cured at 60 degrees Celsius for two hours to form a uniform self-diagnostic and self-healing dual-effect anti-corrosion base layer.

[0039] The surface of the cured anti-corrosion substrate is subjected to plasma activation treatment to improve its surface energy;

[0040] The epoxy resin component and the polysiloxane component are mixed and formulated in a continuously varying mass ratio of 7:3 to 3:7. The mixture is then applied in one continuous coating process to the activated anti-corrosion substrate surface. Subsequently, a segmented temperature-programmed curing process is used, with the temperature increasing from 50 degrees Celsius to 120 degrees Celsius. By utilizing the difference in curing reactivity between the two resin components, the coating spontaneously forms a gradient crosslinking density distribution that continuously transitions from high modulus to low modulus in the thickness direction, thus forming a gradient modulus thermal stress buffer transition layer.

[0041] Silica aerogel particles were surface-modified with a silane coupling agent to replace the hydroxyl groups on their surface with hydrophobic groups, thus obtaining hydrophobically modified aerogel particles.

[0042] The above-mentioned hydrophobic modified aerogel particles, polyimide foaming precursor and three-dimensionally distributed aramid fibers are mixed evenly in a preset ratio. The aerogel particles are chemically grafted and crosslinked in situ onto the surface of the pore wall of the polyimide foam skeleton through an atmospheric pressure foaming process. At the same time, the aramid fibers are naturally distributed inside the skeleton during the foaming process to form a three-dimensional reinforcing network, thus obtaining a closed-cell hydrophobic aramid fiber reinforced aerogel-polyimide composite insulation layer prefabricated sheet.

[0043] The above-mentioned prefabricated composite insulation layer sheet is bonded to the surface of the gradient transition layer, and chemical cross-linking and bonding occur at the interface of the two through a pressurized heating process, forming a connection between the insulation layer and the transition layer.

[0044] The obtained thermal insulation and anti-corrosion integrated composite material is subjected to appearance inspection, adhesion inspection, thermal conductivity inspection and water absorption rate inspection in sequence. After passing the inspection, it is put into storage or applied to the construction of buildings and pipelines on site.

[0045] Upon testing, the composite material obtained in this embodiment did not exhibit interfacial delamination after thermal cycling tests ranging from -40°C to 150°C. Its thermal conductivity and water absorption were both at excellent levels. Furthermore, in the artificial corrosion simulation test, a visible discoloration area appeared around the corrosion point within a short period of time, verifying the effectiveness of the self-diagnostic function.

[0046] In other embodiments, the microcapsule wall material used for the color developer and corrosion inhibitor can be replaced with organic wall materials such as polyurethane or dehydrated gelatin, prepared by interfacial polymerization. The gradient modulus transition layer can also be prepared by a multi-layer spraying process, in which several groups of coatings with different epoxy resin and polysiloxane ratios are prepared according to a preset ratio, and sprayed layer by layer from the anti-corrosion base layer to the insulation layer and cured layer by layer to approximate the effect of continuous gradient modulus distribution. The above alternative methods can also achieve the technical purpose of the present invention.

[0047] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications without departing from the spirit and scope of the present invention. Therefore, any modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope defined by the claims of the present invention.

Claims

1. A novel building insulation and corrosion-resistant material, characterized in that, The system comprises a metal substrate and, sequentially stacked from the metal substrate outwards, a self-diagnostic and self-healing dual-effect anti-corrosion underlayer, a gradient modulus thermal stress buffer transition layer, and a closed-cell hydrophobic aramid fiber reinforced aerogel-polyimide composite insulation layer, the layers of which are chemically cross-linked after plasma activation treatment. The self-diagnostic and self-healing dual-effect anti-corrosion underlayer includes an epoxy resin matrix and mesoporous silica microcapsules dispersed within the epoxy resin matrix. The mesoporous silica microcapsules are loaded with a colorant and a corrosion inhibitor. The gradient modulus thermal stress buffer transition layer is a semi-interpenetrating network composed of epoxy resin and polysiloxane components. The gradient modulus thermal stress buffer transition layer has a continuously changing elastic modulus along its thickness direction. The elastic modulus of the side closer to the self-diagnostic and self-healing dual-effect anti-corrosion bottom layer is higher than that of the side closer to the closed-cell hydrophobic aramid fiber reinforced aerogel-polyimide composite insulation layer. The closed-cell hydrophobic aramid fiber reinforced aerogel-polyimide composite insulation layer includes a polyimide foam skeleton, hydrophobic modified aerogel particles grafted and crosslinked in situ onto the pore wall surface of the polyimide foam skeleton, and a three-dimensional aramid fiber network distributed inside the polyimide foam skeleton. The pores of the polyimide foam skeleton are closed-cell structures. The self-diagnostic and self-healing dual-effect anti-corrosion substrate achieves in-situ early warning through corrosion-triggered microcapsule rupture. The gradient modulus thermal stress buffer transition layer and the self-diagnostic and self-healing dual-effect anti-corrosion substrate transfer and disperse interfacial stress through interfacial chemical cross-linking. The three work together to achieve an integrated coupling function of corrosion early warning, stress buffering and thermal insulation and waterproofing.

2. The novel building insulation and anti-corrosion material according to claim 1, characterized in that: The mesoporous silica microcapsule includes a wall material and a color developer region and a corrosion inhibitor region encapsulated inside the wall material, wherein the color developer region and the corrosion inhibitor region are distributed in sections inside the wall material.

3. The novel building insulation and anti-corrosion material according to claim 1, characterized in that: The color developer is o-phenanthroline, and the corrosion inhibitor is benzotriazole.

4. The novel building insulation and anti-corrosion material according to claim 1, characterized in that: The thickness of the gradient modulus thermal stress buffer transition layer is 50 micrometers to 200 micrometers, and the elastic modulus of the gradient modulus thermal stress buffer transition layer decreases monotonically along the thickness direction.

5. The novel building insulation and anti-corrosion material according to claim 1, characterized in that: The hydrophobically modified aerogel particles are silica aerogel particles that have undergone surface modification treatment with a silane coupling agent, wherein the hydroxyl groups on the surface of the silica aerogel particles are replaced by hydrophobic groups.

6. The novel building insulation and anti-corrosion material according to claim 1, characterized in that: The thickness of the self-diagnostic and self-healing dual-effect anti-corrosion substrate is 80 micrometers to 150 micrometers, and the thickness of the closed-cell hydrophobic aramid fiber reinforced aerogel-polyimide composite insulation layer is 20 millimeters to 40 millimeters.

7. A method for preparing a novel building insulation and anti-corrosion material as described in any one of claims 1 to 6, characterized in that, The process includes the following steps: A metal substrate surface is sequentially subjected to sandblasting and solvent degreasing to obtain a pretreated metal substrate. Mesoporous silica microcapsule wall material is prepared using the sol-gel method. A colorant and corrosion inhibitor are loaded separately into the pores of the mesoporous silica microcapsules. The loaded mesoporous silica microcapsules are then ultrasonically dispersed and mixed into an epoxy resin base material to obtain an anti-corrosion undercoat. This anti-corrosion undercoat is applied to the pretreated metal substrate surface and cured to form a self-diagnostic and self-healing dual-effect anti-corrosion undercoat. The cured surface of the self-diagnostic and self-healing dual-effect anti-corrosion undercoat is then subjected to plasma activation treatment to obtain an activated anti-corrosion undercoat surface. Epoxy resin and polysiloxane components are mixed according to a preset ratio. The mixed mixture is then applied to the activated anti-corrosion undercoat surface and cured using a programmed temperature curing process, causing the coating to form along its thickness direction. A gradient crosslinking density distribution, transitioning continuously from high to low modulus, forms a gradient modulus thermal stress buffer transition layer. Silica aerogel particles are surface-modified with a silane coupling agent to obtain hydrophobic modified aerogel particles. These hydrophobic modified aerogel particles, a polyimide foaming precursor, and three-dimensionally distributed aramid fibers are mixed in a predetermined ratio. An atmospheric pressure foaming process is used to in-situ graft and crosslink the hydrophobic modified aerogel particles onto the pore wall surface of the polyimide foam skeleton. Simultaneously, the aramid fibers are distributed within the polyimide foam skeleton to form a three-dimensional reinforcing network, resulting in a closed-cell hydrophobic aramid fiber-reinforced aerogel-polyimide composite insulation layer prefabricated sheet. This prefabricated sheet is then bonded to the surface of the gradient modulus thermal stress buffer transition layer. A pressurized heating process is then used to chemically crosslink the two at their interface, yielding the novel building insulation and anti-corrosion material.

8. The preparation method of a novel building insulation and anti-corrosion material according to claim 7, characterized in that: The color developer is o-phenanthroline, and the corrosion inhibitor is benzotriazole. The color developer and the corrosion inhibitor are loaded into the pores of the mesoporous silica microcapsules by vacuum impregnation.

9. The preparation method of a novel building insulation and anti-corrosion material according to claim 7, characterized in that: The programmed temperature-curing process includes a segmented temperature curve. By utilizing the difference in curing reactivity between the epoxy resin component and the polysiloxane component, the elastic modulus of the gradient modulus thermal stress buffer transition layer changes continuously along the thickness direction.

10. The preparation method of a novel building insulation and anti-corrosion material according to claim 7, characterized in that: It also includes the steps of sequentially inspecting the obtained new building insulation and anti-corrosion material for appearance, adhesion, thermal conductivity and water absorption.

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