Ecological pug with self-repairing characteristic for repairing cultural relics and buildings and preparation method of ecological pug

Abstract

The invention belongs to the technical field of ecological pug, and discloses cultural relic building repairing ecological pug with a self-repairing characteristic and a preparation method of the cultural relic building repairing ecological pug, and the ecological pug is prepared from the following components in percentage by mass: 40% of kaolin, 20% of bentonite, 10% of konjac glucomannan, 10% of sodium alginate, 8% of microencapsulated liquid silicon resin, 7% of dynamic disulfide bond polymer, 3% of bamboo charcoal powder and 2% of glycerol. According to the invention, a bio-based dynamic dual-network structure is innovatively developed: (1) carboxymethyl cellulose is grafted with a dynamic disulfide bond to form a first network, and room-temperature redox triggered bonding regeneration is realized; and (2) embedding hydroxyl silicone resin into the complex coacervation microcapsule to form a second network, and flowing at low temperature of 50 DEG C to finish damage filling. And the material can be effectively repaired for more than or equal to 50 times in a wide temperature range from-20 DEG C to 80 DEG C (the repair efficiency is maintained to be 85% + / -3%) through double-mechanism synergy. According to the scheme, the industry difficulty that restoration times and ecological compatibility are difficult to achieve at the same time is broken through, and various occasion scene requirements are met.

Description

Technical Field

[0001] The present invention belongs to the technical field of ecological mud materials, and in particular relates to ecological mud materials with self-repairing properties for repairing cultural relics buildings and a preparation method thereof. Background Art

[0002] Current building repair materials primarily rely on petroleum-based polymers (such as epoxy resins and polyurethanes), which suffer from three major drawbacks: ① The high-temperature curing process releases VOCs (toluene / formaldehyde emissions >100 ppm), violating green building standards; ② The static cross-linking network causes a drop in toughness of over 40% after a single repair, making it incapable of withstanding repeated stress damage; and ③ Traditional microcapsule self-healing systems (such as melamine-encapsulated DCPD) require temperatures above 165°C to trigger repair, significantly out of line with normal temperature construction scenarios. These drawbacks are particularly prominent in applications such as restoration in ecologically sensitive areas and the maintenance of cultural relics. Summary of the Invention

[0003] In order to overcome the above technical problems, the present invention provides an ecological mud material for repairing cultural relics and buildings with self-repairing properties and a preparation method thereof.

[0004] The present invention adopts the following technical solutions: Ecological mud materials with self-repairing properties for the restoration of cultural relics and buildings, calculated by mass fraction, include the following: Kaolin 40%, Bentonite 20%, Konjac Glucomannan 10%, Sodium Alginate 10%, Microencapsulated Liquid Silicone Resin 8%, Dynamic Disulfide Bond Polymer 7%, Bamboo Charcoal Powder 3%, Glycerin 2%.

[0005] Preferably, the particle size of the microencapsulated liquid silicone resin is 50-100 μm.

[0006] Preferably, the dynamic disulfide bond polymer uses disulfide bond-modified cellulose.

[0007] Preferably, the bamboo charcoal powder is 200 mesh.

[0008] The present invention also discloses a method for preparing ecological mud material with self-repairing properties for repairing cultural relics and buildings, comprising the following steps: Step 1: Preparation of microencapsulated liquid silicone resin Hydroxyl-terminated polydimethylsiloxane was encapsulated using a complex coacervation method (gelatin-gum arabic); Step 2: Preparation of dynamic disulfide polymers Cystamine (containing disulfide bonds) was grafted onto carboxymethyl cellulose to form a dynamic covalent network; Step 3: Preparation of ecological mud matrix Dry mixing stage: Premix kaolin, bentonite and bamboo charcoal powder and grind through a 200 mesh sieve; Add konjac glucomannan powder and mix well; Wet mixing stage: Slowly add deionized water to the mixture in a blender, with the total amount being water:dry material = 1:2; Add glycerol and stir at 40°C for 30 minutes until a uniform paste is formed; Dynamic cross-linking: Add sodium alginate and continue stirring for 10 min; Add 2% calcium chloride solution (5% of the total amount) dropwise to initiate ionic crosslinking; Step 4: Final product preparation After the matrix is ​​cooled to room temperature, microcapsule powder and dynamic polymer are added; Manual kneading and mixing to avoid high-speed shearing that can damage the microcapsules; Seal and mature for 24 hours to balance the moisture.

[0009] Preferably, the preparation of microencapsulated liquid silicone resin: Dissolve 5g of gelatin and 5g of gum arabic in 100ml of deionized water respectively, stirring at 50℃ to dissolve; Mix the two solutions, add 10 g of liquid silicone resin, and homogenize and emulsify at 10,000 rpm for 2 min; Adjust the pH to 4.5 to induce complex coagulation, and cool to 10°C to solidify the capsule wall; The product was filtered, washed and freeze-dried to obtain a white powder, which was sieved to a particle size of 50-100 μm.

[0010] Preferably, the preparation of dynamic disulfide bond polymers: (1) CMC activation Disperse 10 g of CMC in 200 ml of anhydrous DMF and stir to swell at 60 °C for 1 h; Add 8 ml of epichlorohydrin dropwise (molar ratio CMC unit: epichlorohydrin = 1:2); Add 1g of NaOH powder and react at 75℃ for 6h under nitrogen protection to produce epoxypropyl CMC; The mixture was poured into ice ethanol for precipitation, filtered and washed with DMF three times; Dry under vacuum at 50°C to constant weight (the product is a light yellow flocculent solid); (2) Cystamine grafting (disulfide bond introduction) Prepare 20% cystamine aqueous solution: 5g cystamine dihydrochloride + 20ml deionized water + 3g NaOH to adjust pH to 9.0 Dissolve epoxypropyl CMC in 50ml pH 9.0 borate buffer at a concentration of 5wt% Add cystamine solution (molar ratio of epoxy group: cystamine = 1:1.5), stir and react at 60℃ for 24h, the epoxy group opens and forms a CN bond with the primary amino group of cystamine Add 0.2 g of L-ascorbic acid to maintain the system in a reduced state; (3) Purification and reconstruction Dialysis purification: The reaction solution was transferred into a dialysis bag with a molecular weight cut-off of 8 kDa. - Day 1: Dialysis with flowing deionized water (change water every 2 hours), -Next day: dialyze against 0.1 mM EDTA solution to remove metal ions; The white fibrous solid was obtained by freeze-drying, ground through a 100-mesh sieve, and stored sealed in the dark.

[0011] Compared with the prior art, the present invention has the following beneficial effects: This invention innovatively develops a bio-based dynamic dual-network structure: ① A first network consisting of carboxymethyl cellulose grafted with dynamic disulfide bonds enables room-temperature redox-triggered bond regeneration; ② A second network consisting of complex coacervation microencapsulated hydroxyl silicone resin allows for complete damage filling even at low temperatures of 50°C. These two mechanisms synergistically enable the material to achieve ≥50 effective repairs (maintaining an efficiency of 85% ± 3%) across a wide temperature range of -20°C to 80°C. This solution overcomes the industry's dilemma of balancing repair frequency with ecological compatibility, adapting to diverse application scenarios. DETAILED DESCRIPTION

[0012] The following embodiments of the present invention are described in detail. Unless otherwise specified, the raw materials and equipment used are commercially available or commonly used in the art. The methods in the embodiments, unless otherwise specified, are conventional methods in the art. The embodiments described below are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0013] The ecological mud material for repairing cultural relics buildings with self-repairing properties contains, by mass fraction: 40% kaolin, 20% bentonite, 10% konjac glucomannan, 10% sodium alginate, 8% microencapsulated liquid silicone resin, 7% dynamic disulfide bond polymer, 3% bamboo charcoal powder, and 2% glycerol.

[0014] Ecological mud preparation method 1. Raw material pretreatment Kaolin is dried at 105℃ for 4h, and the whiteness after passing through a 200-mesh sieve is ≥85%, and Fe2O3 is ≤0.8%; The expansion capacity of bentonite after 48 hours of natural drying is ≥15ml / g on a 200-mesh sieve. Bamboo charcoal powder (200 mesh) activated at 120℃ for 2h, iodine adsorption value ≥400mg / g; Konjac glucomannan and glycerol premix (ratio 10:2) were allowed to stand for 24 h until the viscosity reached ≥15,000 mPa·s (1%); Sodium alginate should be stored in a dry place away from light. Particle size D90 should be ≤ 50 μm.

[0015] 2. Preparation of core components 1. Preparation of microencapsulated liquid silicone resin Step 1: Wall material dissolves Gelatin solution: 5 g type A gelatin + 100 ml deionized water → 50°C with magnetic stirring (600 rpm) for 40 min; Gum Arabic solution: 5 g gum Arabic + 100 ml deionized water → ultrasonic dissolution at 55°C (40 kHz, 15 min); Mixing: Mix equal volumes and let stand at 50℃ for 30 minutes to defoam.

[0016] Step 2: Emulsification coating Core: 10g hydroxyl-terminated PDMS (viscosity 1000cP) + 0.2g Span 80; High shear emulsification: homogenization at 10,000 rpm for 2 min in an ice bath (probe diameter 10 mm); Particle size verification: Take emulsion microscopic examination, D 50 =25±5μm.

[0017] Step 3: Complex coagulation and solidification Adjust pH: add 10% citric acid solution dropwise to pH = 4.5 ± 0.1 (titration rate 1 ml / min); Program cooling: 50℃→40℃(2℃ / min)→40℃→25℃(1℃ / min)→25℃→10℃(0.5℃ / min); Cross-linking: add 1 ml of 25% glutaraldehyde dropwise at 10°C (30 min to complete), and continue stirring at 100 rpm for 4 h.

[0018] Step 4: Post-processing Washing: centrifugal washing in deionized water at 10°C (3000 rpm × 10 min) × 3 times; Freeze drying: pre-freeze at -40℃ for 2h → main drying at -25℃ / 10Pa for 24h → 5℃ → 25℃ step-by-step drying; Screening: air flow classification screen 50-100μm (yield> 90%); Output: White free-flowing powder with a moisture content of ≤3%.

[0019] 2. Preparation of dynamic disulfide bond polymers Step 1: CMC activation Reaction system: 10g CMC (degree of substitution 0.92) + 200ml anhydrous DMF → 60℃ swelling for 1h; Functionalization: Add 8 ml of epichlorohydrin dropwise under nitrogen protection (constant pressure dropping funnel, dripping within 30 minutes); Catalysis: 1 g NaOH powder was added in three portions (0 / 2h / 4h), and stirred at 75°C for 6h; Purification: ice-cold ethanol precipitation → DMF elution × 3 → vacuum drying at 50℃ for 12h; Output: light yellow flocculent solid (epoxy value ≥ 0.45 mol / 100 g).

[0020] Step 2: Cystamine grafting Grafting solution: 20% cystamine solution (5 g cystamine dihydrochloride + 3 g NaOH + 20 ml water, pH = 9.0); Reaction: 5% epoxypropyl CMC borate buffer (pH 9.0) + cystamine solution (molar ratio 1:1.5); Conditions: 60°C, dark, stirred for 24 h (sealed with nitrogen) + 0.2 g L-ascorbic acid; Dialysis: 8 kDa dialysis membrane in flowing water for 24 h → 0.1 mM EDTA for 8 h; Freeze-drying: freeze-dry at -50℃ → grind through 100 mesh sieve; Output: white fiber powder (disulfide bond density ≥ 0.8 mmol / g).

[0021] 3. Preparation of ecological mud matrix Dry mixing stage 1. Mineral base material dry mix: 40% kaolin + 20% bentonite + 3% bamboo charcoal powder → three-dimensional mixer 200rpm × 30min; Pass through a 200-mesh vibrating sieve → measure specific surface area (≥15m² / g).

[0022] 2. Polysaccharide addition: Add konjac glucomannan-glycerol premixed colloid → stir at low speed (50 rpm) until there are no agglomerates.

[0023] Wet mixing stage 1. Hydration activation: Slowly add deionized water to the dry material (water: dry material = 1:2); 40℃ planetary stirring (revolution 30rpm + rotation 1200rpm) × 30min → the paste is continuously drawn.

[0024] 2. Ionic crosslinking: Add 10% sodium alginate → stir for 10 minutes; Add 5% 2% CaCl2 solution dropwise (constant rate 1 ml / s) → gel strength instantly increases to ≥8000 cP.

[0025] 4. Final product compounding and maturation Step 1: Add repair components The substrate is cooled to 25±2℃; Manually knead and mix in: 8% microcapsule powder + 7% dynamic disulfide bond polymer; Kneading requirements: frequency 60 times / min×15min (thickness ≤5cm).

[0026] Step 2: Curing and shaping Sealing conditions: double-layer PE film wrapping + constant humidity chamber (25°C, RH=60%); Ripening time: 24 hours (turn over every 8 hours); Output: Gray-brown plastic clay.

[0027] The ecological mud obtained by this process realizes the synergy of triple self-repair mechanisms: ① Short-term repair (0-2h): Ca²⁺ ion migration restructures the alginate network ② Mid-term repair (2-24h): Disulfide bond oxidation and reorganization to restore toughness ③ Long-term repair (>24h): Silicone resin flows out to fill macro cracks Tests show that after 10 damage-repair cycles, the compressive strength retention rate still reaches 89.7%.

[0028] Although the embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations may be made to the above embodiments without departing from the principles and purpose of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. Ecological mud material for repairing cultural relics and buildings with self-repairing properties, characterized in that: In terms of quality score, it includes the following: Kaolin 40%, Bentonite 20%, Konjac Glucomannan 10%, Sodium Alginate 10%, Microencapsulated Liquid Silicone Resin 8%, Dynamic Disulfide Bond Polymer 7%, Bamboo Charcoal Powder 3%, Glycerin 2%.

2. The ecological mud material for repairing cultural relics and buildings with self-repairing properties according to claim 1 is characterized in that: The particle size of microencapsulated liquid silicone resin is 50-100μm.

3. The ecological mud material for repairing cultural relics and buildings with self-repairing properties according to claim 1 is characterized in that: Dynamic disulfide bond polymers use cellulose modified with disulfide bonds.

4. The ecological mud material for repairing cultural relics and buildings with self-repairing properties according to claim 1 is characterized in that: Bamboo charcoal powder 200 mesh.

5. A method for preparing ecological mud materials for repairing cultural relics and buildings with self-repairing properties, characterized in that: The following steps are involved: Step 1: Preparation of microencapsulated liquid silicone resin Hydroxyl-terminated polydimethylsiloxane was encapsulated using a complex coacervation method (gelatin-gum arabic); Step 2: Preparation of dynamic disulfide polymers Cystamine (containing disulfide bonds) was grafted onto carboxymethyl cellulose to form a dynamic covalent network; Step 3: Preparation of ecological mud matrix Dry mixing stage: Premix kaolin, bentonite and bamboo charcoal powder and grind through a 200 mesh sieve; Add konjac glucomannan powder and mix well; Wet mixing stage: Slowly add deionized water to the mixture in a blender, with the total amount being water:dry material = 1:2; Add glycerol and stir at 40°C for 30 minutes until a uniform paste is formed; Dynamic cross-linking: Add sodium alginate and continue stirring for 10 min; Add 2% calcium chloride solution (5% of the total amount) dropwise to initiate ionic crosslinking; Step 4: Final product preparation After the matrix is ​​cooled to room temperature, microcapsule powder and dynamic polymer are added; Manual kneading and mixing to avoid high-speed shearing that can damage the microcapsules; Seal and mature for 24 hours to balance the moisture.

6. The method for preparing ecological mud material for repairing cultural relics and buildings with self-repairing properties according to claim 5, characterized in that: Preparation of microencapsulated liquid silicone resin: Dissolve 5g of gelatin and 5g of gum arabic in 100ml of deionized water respectively, stirring at 50℃ to dissolve; Mix the two solutions, add 10 g of liquid silicone resin, and homogenize and emulsify at 10,000 rpm for 2 min; Adjust the pH to 4.5 to induce complex coagulation, and cool to 10°C to solidify the capsule wall; The product was filtered, washed and freeze-dried to obtain a white powder, which was sieved to a particle size of 50-100 μm.

7. The method for preparing ecological mud material for repairing cultural relics and buildings with self-repairing properties according to claim 5, characterized in that: Preparation of dynamic disulfide bond polymers: (1) CMC activation Disperse 10 g of CMC in 200 ml of anhydrous DMF and stir to swell at 60 °C for 1 h; Add 8 ml of epichlorohydrin dropwise (molar ratio CMC unit: epichlorohydrin = 1:2); Add 1g of NaOH powder and react at 75℃ for 6h under nitrogen protection to produce epoxypropyl CMC; The mixture was poured into ice ethanol for precipitation, filtered and washed with DMF three times; Dry under vacuum at 50°C to constant weight (the product is a light yellow flocculent solid); (2) Cystamine grafting (disulfide bond introduction) Prepare 20% cystamine aqueous solution: 5g cystamine dihydrochloride + 20ml deionized water + 3g NaOH to adjust pH to 9.0 Dissolve epoxypropyl CMC in 50ml pH 9.0 borate buffer at a concentration of 5wt% Add cystamine solution (molar ratio of epoxy group: cystamine = 1:1.5), stir and react at 60℃ for 24h, the epoxy group opens and forms a CN bond with the primary amino group of cystamine Add 0.2 g of L-ascorbic acid to maintain the system in a reduced state; (3) Purification and reconstruction Dialysis purification: The reaction solution was transferred into a dialysis bag with a molecular weight cut-off of 8 kDa. - Day 1: Dialysis with flowing deionized water (change water every 2 hours), -Next day: dialyze against 0.1 mM EDTA solution to remove metal ions; The white fibrous solid was obtained by freeze-drying, ground through a 100-mesh sieve, and stored sealed in the dark.