PH value response type self-adhesive heat preservation and moisture preservation blanket and preparation method thereof

Abstract

The invention discloses a pH value response type self-adhesive heat preservation and moisture preservation blanket and a preparation method and application thereof, and belongs to the technical field of composites.The heat preservation and moisture preservation blanket is of a multi-layer composite structure and sequentially comprises flame-retardant canvas, an aluminum foil rubber and plastic plate, composite geotechnical cloth and a sticky felt hydrogel layer from outside to inside; the adhesive felt hydrogel layer is of a structure which takes an adhesive felt as a framework, is impregnated with a hydrogel precursor solution and then is formed through thermal crosslinking, and the hydrogel precursor solution comprises the following components in parts by weight: 50-80 parts of methacrylic acid esterified polyethyleneimine, 20-40 parts of carboxymethyl cellulose, 10-30 parts of polyethylene glycol diglycidyl ether, 1-3 parts of 1, 3-propylene glycol, 1-3 parts of 1, 3-propylene glycol, 1-3 parts of 1, 3-propylene glycol, 1-3 parts of 1, 3-propylene glycol, 1-3 parts of 1, 3-propylene glycol and 1-3 parts of 1, 3-propylene glycol. And 18 to 30 parts of 4-chloropropanol-piperazine. The heat preservation and moisture preservation blanket with the adhesive felt hydrogel layer and with the pH value response has the advantages of being easy to operate and good in heat preservation and moisture preservation effect.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of composite materials, and particularly relates to a pH value responsive self-adhesive heat and moisture retaining blanket and a preparation method thereof. BACKGROUND

[0002] With the rapid development of economy, mass concrete is more and more used in key parts of ship lock main structure, foundation slab of large public building, pile foundation cap, etc. Considering the crack control, strength and cost and other related factors, mass concrete of ship lock main structure uses mass three-grade concrete. The load borne by mass concrete structure mainly includes two kinds, one is the external load borne by the structure, including dead load, live load borne in normal use, acceleration load due to seismic wave when earthquake occurs, wind load, etc. The other is the creep of the structure with time or the stress caused in the pouring process. For mass concrete, the temperature stress caused by hydration reaction is particularly important. The temperature stress of mass concrete structure is mainly caused by the following reasons. In the construction process, in order to ensure the continuity of the structure, a large amount of concrete is poured at one time, the heat generated by the hydration reaction of the concrete has not yet been dissipated, the newly poured concrete is covered, and the poor thermal conductivity of the concrete itself causes a large amount of hydration heat to gather together to generate a large temperature stress, and the uneven distribution of the concrete mixture causes concentrated stress, thereby causing local cracking. This kind of crack exists universally in mass concrete structure and is easy to develop into a larger penetrating crack, which endangers the safety of the structure.

[0003] For the crack control of mass concrete, the concrete material and the proportioning are generally controlled, and the internal and external temperature difference of the concrete is controlled. The method for controlling the internal and external temperature difference of the concrete generally includes external cooling by sprinkling water on the outer surface of the mass concrete and covering the surface of the mass concrete with a wrapping material, etc. Especially in winter or summer construction, the phenomenon of excessive internal and external temperature difference is easy to occur when the temperature of the concrete curing condition is low, or the phenomenon of dry cracking of the concrete is easy to occur when the sun is too hot. Therefore, the concrete needs to maintain appropriate humidity and temperature during the curing process to reduce the occurrence of surface cracks. However, the existing curing materials have the following problems: insufficient moisture retention performance (<24h), causing humidity fluctuation, being unable to effectively maintain the wet state of the surface of the concrete, and needing frequent water replenishment; high thermal conductivity (0.3-0.5 W / (m·K)), poor temperature control performance, causing thermal stress cracks, and lacking self-repairing function, being unable to cope with micro-cracks. SUMMARY

[0004] In order to overcome the above-mentioned deficiencies of the prior art, the present application provides a pH value responsive self-adhesive heat and moisture preservation blanket and a preparation method thereof, wherein a water gel precursor solution is impregnated into a skeleton of adhesive felt, and then a heat cross-linking process is performed to form a structure of the adhesive felt water gel layer, wherein the water gel is a self-adhesive water gel layer with pH value responsiveness.

[0005] The technical solution for achieving the object of the present application is as follows:

[0006] The present application provides a pH value responsive self-adhesive heat and moisture preservation blanket, which is a multi-layer composite structure, and comprises, from the outside to the inside, a flame-retardant canvas, an aluminum foil and rubber plastic plate, a composite geotextile, and an adhesive felt water gel layer; the adhesive felt water gel layer is formed by impregnating a water gel precursor solution into a skeleton of adhesive felt, and then performing a heat cross-linking process; the water gel precursor solution comprises, in terms of weight parts, 50-80 parts of methacrylated polyethyleneimine, 20-40 parts of carboxymethyl cellulose, 10-30 parts of polyethylene glycol diglycidyl ether, and 18-30 parts of 1,4-chloropropanol-piperazine.

[0007] The structure of the 1,4-chloropropanol-piperazine is shown in Formula 1.

[0008]

[0009] The use of 1,4-chloropropanol-piperazine as a cross-linking agent can control the maximum swelling of methacrylated polyethyleneimine at a neutral pH, thereby facilitating the heat and moisture preservation blanket to achieve the maximum water absorption effect; at an alkaline pH, the deprotonation of the cross-linking network causes the shrinkage and release of stored water, thereby supplementing the large amount of water required during the early stage of concrete hardening.

[0010] Preferably, the adhesive felt is a hydrophilic adhesive felt, and the hydrophilic adhesive felt is a water-absorbing needle-punched non-woven fabric.

[0011] Preferably, the preparation method of the 1,4-chloropropanol-piperazine is as follows: 1 equivalent of piperazine is dissolved in distilled water, 2-2.5 equivalents of epichlorohydrin are added at 25-35°C, and the reaction is continued at 50-60°C for 12-24 hours.

[0012] Preferably, the preparation method of the methacrylated polyethyleneimine is as follows: the polyethyleneimine is pre-dried under vacuum, dichloromethane and triethylamine are added under argon protection, the solution is activated for a period of time, methacrylic anhydride is added, and the reaction is continuously stirred at room temperature for 12-20 hours under argon protection, and then the methacrylated polyethyleneimine is obtained after purification and drying. The molar amount of the methacrylic anhydride added is 10-30 times the molar amount of the polyethyleneimine.

[0013] It should be noted that the methacrylated polyethyleneimine is only partially methacrylated polyethyleneimine, because the polyethyleneimine itself contains a high density of amine groups, which are easily protonated in water to form positively charged -NR3 + , resulting in strong electrostatic repulsion, hindering the close packing of chain segments, while methacrylation can balance the electrostatic repulsion and chain segment interaction by partially neutralizing the amine group charge, facilitating the formation of a loose and porous network by the polymer chains through hydrophobic interaction and hydrogen bonding, thereby accommodating more water molecules.

[0014] Preferably, the polyethyleneimine is branched polyethyleneimine with a weight average molecular weight of 10000-50000 g / mol.

[0015] Preferably, the polyethylene glycol diglycidyl ether has a weight average molecular weight of 400-600 g / mol.

[0016] The application also protects a preparation method of a pH value responsive self-adhesive heat and moisture retaining blanket, comprising the following steps:

[0017] (1) Pre-mixing and stirring carboxymethyl cellulose solution, methacrylated polyethyleneimine solution, polyethylene glycol diglycidyl ether, and 1,4-chloropropanol-piperazine solution to obtain a hydrogel precursor solution, then completely immersing the adhesive felt in the hydrogel precursor solution for a period of time for adsorption, then draining after taking out, and then transferring to an oven for crosslinking reaction at 60-80℃ for 3-5 hours, then taking out and cooling to room temperature;

[0018] (2) successively bonding or sewing the flame-retardant canvas, aluminum foil rubber plastic plate, composite geotextile, and adhesive felt hydrogel, and then cutting and hemming to obtain the pH value responsive self-adhesive heat and moisture retaining blanket.

[0019] The application also protects the application of a pH value responsive self-adhesive heat and moisture retaining blanket in agricultural irrigation, geological remediation, and building insulation.

[0020] Beneficial effects

[0021] The present application comprises the following beneficial effects: the present application provides a pH value responsive self-adhesive heat and moisture preservation blanket, which adopts a multi-layer composite structure and is designed with a pH value responsive self-adhesive felt water gel layer. Before use, the heat and moisture preservation blanket is first soaked in water to swell, and then is directly covered on the surface of the concrete to be cured through the adhesion between the water gel and the concrete. In the early curing of the concrete, the amine groups of the methacrylated polyethyleneimine in the water gel are protonated, the water gel network shrinks, and the stored water is released to the surface of the concrete, but at the same time, the deprotonation of the carboxymethyl cellulose carboxylic acid groups also absorbs part of the free water, so that the water in the heat and moisture preservation blanket is not lost at one time, thereby exceeding the absorption limit of the concrete hydration reaction; with the later hardening of the concrete, the free water stored in the carboxymethyl cellulose in the water gel layer is slowly released, continuously supplementing the water for the slow hydration reaction on the surface of the concrete, ensuring the humidity environment on the surface of the concrete, and reducing the generation of cracks through the self-repairing effect of the concrete hydration. When the water in the felt water gel layer of the heat and moisture preservation blanket is almost consumed, the adhesion between the heat and moisture preservation blanket and the concrete interface decreases, and the heat and moisture preservation blanket falls off or loosens. At this time, the heat and moisture preservation blanket can be reused by being placed in clean water to swell, and has the characteristics of simple operation and good heat and moisture preservation effect. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a 1,4-chloropropanol-piperazine synthesis step and structural schematic diagram;

[0023] Figure 2 is a nuclear magnetic resonance spectrum of 1,4-chloropropanol-piperazine;

[0024] Figure 3 is an infrared spectrum of methacrylated polyethyleneimine. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0026] In the embodiments, the experimental methods used are conventional methods unless otherwise specified, and the materials, reagents, etc. used are commercially available unless otherwise specified.

[0027] The raw materials and equipment used in the examples and comparative examples will be described as follows:

[0028] Piperazine: 99%, Shanghai Aladdin Bio-Chem Technology Co., Ltd.;

[0029] Epichlorohydrin: 99%, Shanghai Macklin Biochemical Technology Co., Ltd.;

[0030] Carboxymethylcellulose: industrial grade, Hubei Zhonglong Kangsheng Fine Chemical Co., Ltd.;

[0031] Polyethylene glycol diglycidyl ether: molecular weight 400 g / mol, purchased from Tianjin Xinsisheng Biochemical Technology Co., Ltd.;

[0032] Polyethyleneimine: branched polyethyleneimine, average Mw ~ 25000, Shanghai Yuan Ye Biological Technology Co., Ltd.;

[0033] Methacrylic anhydride: 94%, Shanghai Macklin Biochemical Technology Co., Ltd.;

[0034] Aluminum foil rubber plastic plate: thermal conductivity <0.034 W / (m·K), Hebei Osmose Rubber Plastic Heat Insulation Material Co., Ltd.;

[0035] Composite geotextile: polyester filament composite geotextile, thickness 1 mm, Shandong Xingzhao Environmental Science and Technology Co., Ltd.;

[0036] Flame-retardant canvas: thickness 0.8 mm, purchased from Dacheng County Angang Fireproof Material Factory

[0037] Adhesive felt: water-absorbing needled non-woven fabric, thickness 5 mm, Weixian Runhua Felt Product Sales Co., Ltd.; 1 m x 1 m;

[0038] 1,4-chloropropanol-piperazine: 0.023 mol piperazine was dissolved in 18.2 ml distilled water, the temperature was controlled at 25-35°C by water-ice bath, 0.046 mol epichlorohydrin was slowly added, after stirring for 20 min, the water-ice bath was removed, and the reaction was continued at 50°C for 12 h to obtain 1,4-chloropropanol-piperazine. The nuclear magnetic hydrogen spectrum is shown in Figure 2

[0039] Methacrylated polyethyleneimine 1: 4 mmol of vacuum-dried polyethyleneimine was added to a round-bottom flask, purged with argon for 30 min, 300 ml of dichloromethane and 1 mL of triethylamine were added under argon protection, and the primary and secondary amine groups of the polyethyleneimine were activated by stirring for 5 min, 0.1 mol of methacrylic anhydride was added, and the reaction was continuously stirred at room temperature under argon protection for 18 hours. The residual dichloromethane was removed by vacuum drying for 12 hours, and the unreacted methacrylic anhydride and triethylamine were removed by washing with deionized water and ethanol. After vacuum drying for 48 hours, methacrylated polyethyleneimine 1 was obtained. The infrared spectrum is shown in Figure 3 , wherein 1106 cm -1 corresponds to the C-N stretching vibration of the secondary amine, 1307 cm -1 corresponds to the C-N stretching vibration and CH bending vibration of the primary amine, and 1468 cm​-1 The peaks at 1654 cm -1 and 1620 cm -1 correspond to the C=0 stretching vibration in the amide group, confirming the formation of the amide group, while the peak at 1548 cm -1 corresponds to the C-N stretching vibration. In addition, the broad absorption band in the 3600-3200 cm -1 interval originates from the O-H stretching vibration of intra- and intermolecular hydrogen bonds, while the vibration band between 2959-2825 cm -1 corresponds to the C-H stretching vibration of the alkyl group.

[0040] Methacrylated polyethyleneimine 2: compared to methacrylated polyethyleneimine 1, the difference is that 0.1 mol methacrylic anhydride is replaced by 0.04 mol methacrylic anhydride;

[0041] Methacrylated polyethyleneimine 3: compared to methacrylated polyethyleneimine 1, the difference is that 0.1 mol methacrylic anhydride is replaced by 0.15 mol methacrylic anhydride;

[0042] Methacrylated polyethyleneimine 4: compared to methacrylated polyethyleneimine 1, the difference is that 0.1 mol methacrylic anhydride is replaced by 0.02 mol methacrylic anhydride;

[0043] Examples and comparative examples

[0044] A pH value responsive self-adhesive heat and moisture retaining blanket, the preparation method comprising the following steps

[0045] (1) Dissolve carboxymethyl cellulose in 1.0M KOH alkaline solution to prepare a carboxymethyl cellulose solution with a concentration of 0.3g / ml; dissolve methacrylated polyethyleneimine in distilled water to prepare a solution with a concentration of 0.1g / ml; mix polyethylene glycol diglycidyl ether with 1,4-chloropropanol-piperazine solution;

[0046] (2) Pre-mix and stir the carboxymethyl cellulose solution, methacrylated polyethyleneimine solution, and crosslinking agent solution for 30 minutes to obtain a hydrogel precursor solution, then completely immerse the adhesive felt in the hydrogel precursor solution for 30 minutes of adsorption and penetration, then drain after taking out, and then transfer to an oven for crosslinking reaction at 80°C for 3 hours, then take out and cool to room temperature;

[0047] (3) successively bond or sew the flame-retardant canvas, aluminum foil rubber plastic plate, composite geotextile, and adhesive felt hydrogel, and then cut and edge to obtain the pH value responsive self-adhesive heat and moisture retaining blanket.

[0048] The composition and the amount of the hydrogel precursor solution used in each example and the comparative example are shown in Table 1.

[0049] Table 1 Composition and amount of the hydrogel precursor solution (parts by weight)

[0050]

[0051]

[0052] The following are the test methods for the performance parameters involved in the present application, and the test results are shown in Table 2.

[0053] 1. Water absorption and swelling capacity of the adhesive felt hydrogel layer: The adhesive felt hydrogel layer is allowed to absorb water and swell in a buffer solution with a pH value of 7 and 12 for 2 days, the surface water is removed with a paper towel, the sample is weighed W1, then dried in an oven at 110°C for 15 hours, the dried sample is weighed W2, and the water absorption and swelling capacity is calculated as SC = (W1-W2) / W2 x 100%.

[0054] 2. Moisture retention performance: The heat and moisture retention blanket prepared from the examples and the comparative example is allowed to absorb water and swell in water for 12 hours, then covered on the concrete test block, the constant temperature is 20±2°C, 3 high-precision humidity sensors are uniformly arranged on the surface of the concrete test block, and the humidity data is recorded every 30 minutes, and the monitoring is continued for 7 days. The relative humidity on the 1st day, the 3rd day and the 7th day is recorded.

[0055] 3. Cracking of concrete: The standard point-line gauge film ruler is compared with the card and the crack situation on the 7th day is measured, and the total length of the crack, the average length of the crack and the maximum width of the crack are recorded.

[0056] Table 2 Performance test of examples and comparative examples

[0057]

[0058]

[0059] As can be seen from Examples 3-6 and Comparative Example 1, the water absorption and swelling capacity of the polyethyleneimine modified by methacrylate is significantly enhanced, but too much methacrylic acid modification will affect the crosslinking density of the polyethyleneimine, thereby reducing the water absorption and swelling capacity of the adhesive felt hydrogel layer. The optimal water absorption and swelling effect can be achieved when the molar amount of the methacrylic anhydride added is 10-30 times the molar amount of the polyethyleneimine.

[0060] From Examples 1-3, it can be seen that the methacrylate polyethyleneimine and carboxymethyl cellulose need to be controlled at a certain ratio, at which the pH response of the heat and moisture retention blanket to the water absorption / desorption performance is consistent with the water demand of the concrete hydration reaction, and the heat and moisture retention effect is better. From Comparative Example 3, it can be seen that the water absorption and swelling capacity and the moisture retention performance of Comparative Example 3 without using 1,4-chloropropanol-piperazine are significantly reduced, and the concrete cracks are serious, which is likely because the crosslinking network density is insufficient when only using polyethylene glycol diglycidyl ether as the crosslinking agent, affecting the water absorption and retention capacity of the hydrogel.

[0061] The preferred embodiments of the application disclosed above are only used to help explain the application. The preferred embodiments do not describe all the details and limit the application to the specific embodiments described. Obviously, many modifications and variations can be made according to the content of the specification. The specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the application, so that those skilled in the art can well understand and utilize the application. The application is limited only by the claims and their full scope and equivalents.

Claims

1. A pH-responsive self-adhesive heat-insulating and moisture-retaining blanket, characterized in that, The heat-insulating and moisture-retaining blanket has a multi-layer composite structure, consisting of flame-retardant canvas, aluminum foil rubber-plastic board, composite geotextile, and adhesive felt hydrogel layer from the outside to the inside. The adhesive felt hydrogel layer is formed by impregnating a hydrogel precursor solution with adhesive felt as the skeleton and then thermally cross-linking it. The hydrogel precursor solution, by weight, includes 50-80 parts of methacrylated polyethyleneimine, 20-40 parts of carboxymethyl cellulose, 10-30 parts of polyethylene glycol diglycidyl ether, and 18-30 parts of 1,4-chloropropanol-piperazine.

2. The pH-responsive self-adhesive heat-insulating and moisture-retaining blanket as described in claim 1, characterized in that, The structural formula of the 1,4-chloropropanol-piperazine is shown in Formula 1:

3. The pH-responsive self-adhesive heat-insulating and moisture-retaining blanket as described in claim 1, characterized in that, The adhesive felt is a hydrophilic adhesive felt, which is a water-absorbing needle-punched nonwoven fabric.

4. The pH-responsive self-adhesive heat-insulating and moisture-retaining blanket as described in claim 1, characterized in that, The preparation method of the 1,4-chloropropanol-piperazine is as follows: dissolve 1 equivalent of piperazine in distilled water, add 2 to 2.2 equivalents of epichlorohydrin at 25-35°C, and continue stirring the reaction at 50-60°C for 12 to 24 hours to obtain the product.

5. The pH-responsive self-adhesive heat-insulating and moisture-retaining blanket as described in claim 1, characterized in that, The method for preparing methacrylated polyethyleneimine is as follows: polyethyleneimine is pre-dried under vacuum, dichloromethane and triethylamine are added under argon protection, dissolved and activated for a period of time, methacrylic anhydride is added, and the reaction is continuously stirred at room temperature for 12-20 hours under argon protection. After purification and drying, methacrylated polyethyleneimine is obtained.

6. The pH-responsive self-adhesive heat-insulating and moisture-retaining blanket as described in claim 5, characterized in that, The molar amount of methacrylic anhydride added is 10 to 30 times the molar amount of polyethyleneimine.

7. The pH-responsive self-adhesive heat-insulating and moisture-retaining blanket as described in claim 5, characterized in that, The polyethyleneimine is a branched polyethyleneimine with a weight-average molecular weight of 10,000 to 50,000 g / mol.

8. The pH-responsive self-adhesive heat-insulating and moisture-retaining blanket as described in claim 1, characterized in that, The weight-average molecular weight of the polyethylene glycol diglycidyl ether is 400–600 g / mol.

9. A method for preparing a pH-responsive self-adhesive thermal and moisture-retaining blanket as described in any one of claims 1 to 8, characterized in that, Includes the following steps: (1) Carboxymethyl cellulose solution, methacrylated polyethyleneimine solution, polyethylene glycol diglycidyl ether and 1,4-chloropropanol-piperazine solution are premixed and stirred to obtain a hydrogel precursor solution. Then, the adhesive felt is completely immersed in the hydrogel precursor solution for a period of time to penetrate and adsorb. After being taken out and drained, it is transferred to an oven and crosslinked at 60-80℃ for 3-5 hours. After being taken out and cooled to room temperature. (2) Flame-retardant canvas, aluminum foil rubber and plastic board, composite geotextile and adhesive felt hydrogel are bonded or sewn together in sequence, and then cut and sewn to obtain pH-responsive self-adhesive heat preservation and moisture retention blanket.

10. The application of a pH-responsive self-adhesive thermal insulation blanket as described in any one of claims 1 to 8 in agricultural irrigation, geological restoration, and building insulation.

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