Highly moisture-permeable low thermal-conductivity wall material and its preparation method

Abstract

The application discloses a kind of high moisture-permeable low thermal-conductive wall materials and preparation method thereof, relate to wall material technical field, solve the problem that prior art is difficult to meet the requirements of high moisture-permeable and low thermal-conductive simultaneously.Wall material includes polylactic acid, 50~60 parts;Acrylate emulsion, 6~10 parts;Interface modification silicon dioxide, 20~25 parts;Quaternary ammonium salt modified montmorillonite, 0.5~1 parts;Dichloromethane, 2~4 parts;Cellulose nanocrystal, 0.2~0.4 parts;The interface modification silicon dioxide is with silicon dioxide particle as matrix, from inside to outside, sequentially coated with by silane coupling agent KH-560 and hexadecyltrichlorosilane composition bottom color inner layer, by polyethylene glycol PEG-400 and propylene glycol composition middle layer and by acrylic monomer composition outer layer;The quaternary ammonium salt modified montmorillonite is with sodium-based montmorillonite as matrix, and is prepared by hexadecyltrimethylammonium bromide ion exchange modification.The application can be widely used in high frequency humid space building.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wall materials, in particular to a high-moisture-permeable and low-thermal-conductive wall material and a preparation method thereof. BACKGROUND

[0002] Under the dual driving of building energy saving and indoor comfortable environment demand, the high-moisture-permeable and low-thermal-conductive performance of wall materials has become the core research and development direction, especially in humid areas such as bathrooms and kitchens, the material needs to have the functions of efficiently discharging internal moisture, blocking heat transfer and inhibiting mold breeding at the same time, so as to solve the problems of traditional wall body such as easy condensation, mold and cold bridge in winter.

[0003] At present, the research on high-moisture-permeable and low-thermal-conductive wall materials in the industry still has many technical bottlenecks, which is difficult to meet the use demand in humid areas. On the one hand, the moisture permeability and thermal insulation performance are difficult to be optimized simultaneously. The existing technology mostly adopts a simple mixing system of organic phase and single modified inorganic phase, although the inorganic phase particles can construct certain moisture permeation channels, the difference in hydrophilic and hydrophobic properties between the inorganic phase and the organic phase is large, and the interface is easy to form a diffusion resistance of water molecules, which makes it difficult to improve the moisture permeability; at the same time, the interface is not tightly combined, which is easy to produce heat conduction gap, so that the overall thermal conductivity of the material increases, and the dual goals of high moisture permeability and low thermal conductivity cannot be achieved. On the other hand, the antifungal property and material stability are insufficient in humid environment. In order to solve the mold problem in humid environment, some schemes directly add small molecule antifungal agents such as thiazoline ketone, but such antifungal agents are easy to migrate and lose with moisture, resulting in poor long-term antifungal effect.

[0004] In summary, how to break through the performance balance difficulty of moisture permeability, thermal insulation and mold resistance through precise design of components and synergistic innovation of process has become a key technical problem to be solved in the field of building. SUMMARY

[0005] In order to solve the problem that the existing technology cannot simultaneously meet the requirements of high moisture permeability and low thermal conductivity, the present application provides a high-moisture-permeable and low-thermal-conductive wall material and a preparation method thereof.

[0006] The technical scheme of the present application is as follows:

[0007] A high-moisture-permeable and low-thermal-conductive wall material, comprising the following components in mass fraction:

[0008] 50-60 parts of polylactic acid, 6-10 parts of acrylate emulsion;

[0009] 20-25 parts of interfacial modified silicon dioxide;

[0010] 0.5-1 part of quaternary ammonium salt modified montmorillonite, 2-4 parts of dichloromethane, and 0.2-0.4 parts of cellulose nanocrystal;

[0011] The interface modified silica is based on silica particles, which are coated with an inner layer of silane coupling agent KH-560 and hexadecyltrichlorosilane, a middle layer of polyethylene glycol (PEG-400) and propylene glycol, and an outer layer of acrylic monomer from inside to outside.

[0012] The quaternary ammonium salt modified montmorillonite is based on sodium montmorillonite, which is modified by ion exchange with hexadecyltrimethylammonium bromide.

[0013] Preferably, the number average molecular weight of the polylactic acid is 80000-100000 Da, the solid content of the acrylic ester emulsion is 45-50%, and the particle size of the silica particles is 1-3 μm.

[0014] Preferably, the specific preparation process of the interface modified silica comprises:

[0015] The silica particles are added into anhydrous ethanol and ultrasonically dispersed to form a silica dispersion liquid with a concentration of 30%-35%;

[0016] The silane coupling agent KH-560 and hexadecyltrichlorosilane are added into anhydrous ethanol and stirred to dissolve, and then ultrasonic atomization spraying is performed on the surface of the silica dispersion liquid, followed by stirring and reaction in a 35℃ constant temperature water bath to form an inner layer.

[0017] PEG-400 and propylene glycol are added into anhydrous ethanol and stirred to dissolve, and then ultrasonic atomization spraying is performed on the surface of the silica particles modified in the inner layer, followed by stirring and reaction in a 40℃ constant temperature water bath to form a middle layer.

[0018] Acrylic ester monomers are added into the above system and ultrasonically dispersed to form an outer layer.

[0019] Preferably, the mass ratio of the silane coupling agent KH-560 and hexadecyltrichlorosilane is 7:3, and the total mass of the two is 5%-6% of the mass of the silica particles.

[0020] Preferably, the mass ratio of the PEG-400 and propylene glycol is 1:1, and the total mass of the two is 6%-7% of the mass of the silica particles; the mass of the acrylic ester monomers is 4%-5% of the mass of the silica particles.

[0021] Preferably, the specific preparation process of the quaternary ammonium salt modified montmorillonite comprises:

[0022] Sodium montmorillonite is weighed and added into deionized water and stirred to disperse, forming a montmorillonite suspension with a mass concentration of 5%; hydrochloric acid is added dropwise into the suspension to adjust the pH value to 3-4; after ultrasonic treatment, the upper layer of the suspension is taken and reserved for use;

[0023] Dissolve hexadecyl trimethyl ammonium bromide in a 60℃ constant temperature water bath, and prepare a quaternary ammonium salt solution with a concentration of 0.12 mol / L;

[0024] Warm the upper suspension to 60℃, continuously stir, and add the quaternary ammonium salt solution drop by drop, and then continue to warm and stir for 4h;

[0025] Centrifuge the mixed system, discard the supernatant, and then repeatedly precipitate with ethanol, vacuum dry, grind, sieve, and obtain the quaternary ammonium salt modified montmorillonite.

[0026] Preferably, the mass ratio of the sodium-based montmorillonite and the hexadecyl trimethyl ammonium bromide is 10:3.5~5.5.

[0027] The application also provides a preparation method of the high-moisture-permeable low-thermal-conductivity wall material.

[0028] S1, dichloromethane is added to a container, polylactic acid, acrylate emulsion, and quaternary ammonium salt modified montmorillonite are added, and stirring is performed to obtain a uniform organic phase matrix;

[0029] S2, interfacial modification silica and cellulose nanocrystals are added to the organic phase matrix, and stirring is performed to form a uniform slurry system; the slurry is poured into a mold, and the mold is placed in a constant temperature and humidity environment for standing;

[0030] S3, the mold is transferred into a forced air drying oven, and after temperature curing, the temperature is naturally lowered to room temperature, the mold is demolded, and a high-moisture-permeable low-thermal-conductivity wall material is obtained.

[0031] Preferably, the temperature of the constant temperature and humidity environment in step S2 is 25℃, and the relative humidity is 60%.

[0032] Preferably, in step S3, the temperature curing is specifically as follows: first, drying at 40℃ for 4h; then, increasing the temperature to 60℃, and temperature curing for 3h; and then, increasing the temperature to 70℃, and temperature curing for 2h.

[0033] Compared with the prior art, the application has the following specific advantages:

[0034] 1. The application constructs a three-layer modified interface from the inside to the outside with silica particles as the matrix, the inner layer is strengthened with a silicon-oxygen bond and is hydrophobic, reducing the adsorption and retention of water molecules, the middle layer realizes smooth transition of hydrophilicity and hydrophobicity, reducing the diffusion resistance of water molecules across the interface, the outer layer is copolymerized with the organic phase matrix to form a chemical bond, eliminating the interface heat conduction gap, greatly improving the moisture permeability of the material, reducing the thermal conductivity, and improving the stability of the material.

[0035] 2. The application grafts long-chain quaternary ammonium salt cations to the interlayer of montmorillonite by ion exchange between cetyltrimethylammonium bromide and interlayer sodium ions of sodium-based montmorillonite. On the one hand, the long-chain alkyl improves the compatibility of montmorillonite with polylactic acid-acrylate organic phase, avoiding agglomeration and blocking the moisture permeation channel. On the other hand, the quaternary ammonium salt cations can destroy the cell membrane of mold, achieve long-acting antibacterial, and the modified montmorillonite is uniformly dispersed, and the mold-proof ingredient is not easy to lose with moisture.

[0036] 3. The application uses cellulose nanocrystals, which can slowly crystallize in the vertical direction in the organic phase matrix, and the vertical through-type moisture permeation channel is formed by guiding the three-layer gradient interface modified silica particles through the crystal framework; at the same time, the directional arrangement of the silica particles can form a continuous heat barrier network, avoiding the heat flow caused by random distribution of particles, and improving the moisture permeability and heat insulation stability. DETAILED DESCRIPTION

[0037] In order to make the technical scheme of the application clearer, the technical scheme in the embodiments of the application will be described clearly and completely below. It should be noted that the following embodiments are only used to better understand the technical scheme of the application, and should not be understood as a limitation of the application.

[0038] Example 1.

[0039] (1) Preparation of interface modified silica:

[0040] Take 20g of silica particles, add 46.7g of anhydrous ethanol, and stir in a 250mL beaker at 500r / min for 10min, then transfer to a 300W ultrasonic cleaning machine, and ultrasonic for 30min at 25℃, to obtain a silica dispersion liquid;

[0041] Mix 0.7g of KH-560 with 0.3g of hexadecyltrichlorosilane, add 5g of anhydrous ethanol, and stir at 600r / min for 15min to dissolve, then spray on the surface of the dispersion liquid by ultrasonic atomization, and stir at 35℃ constant temperature water bath at 300r / min for 1h to form an inner layer;

[0042] Mix 1.2g of PEG-400 with 1.2g of propylene glycol, add 9.6g of anhydrous ethanol, and stir at 400r / min for 10min to dissolve, then spray by ultrasonic atomization, and stir at 40℃ constant temperature water bath at 250r / min for 45min to form a middle layer;

[0043] Add 0.8g of acrylate monomer, and ultrasonic for 15min at 200W to obtain interface modified silica.

[0044] (2) Preparation of quaternary ammonium salt modified montmorillonite:

[0045] Take 0.47g sodium-based montmorillonite, add 8.93g deionized water, stir at 500r / min for 10min, add 1mol / L hydrochloric acid 0.16mL, adjust pH to 3~4, 400W ultrasonic for 30min, stand for 2h, take the upper suspension;

[0046] Take 0.17g CTAB, add 5mL deionized water, 60℃ constant temperature water bath, stir at 600r / min for 15min, get 0.12mol / L quaternary ammonium salt solution;

[0047] Warm the upper suspension to 60℃, stir at 400r / min, add quaternary ammonium salt solution drop by drop (1-2 drops / sec), 60℃ incubation and stirring for 4h, during which bromophenol blue indicator is used to verify the completion of the reaction;

[0048] Centrifuge at 6000r / min for 15min, discard the supernatant, wash with ethanol 3 times, vacuum dry at 60℃ for 12h, grind through 100 mesh sieve, get quaternary ammonium salt modified montmorillonite.

[0049] (3) Wall material preparation:

[0050] Add 2g dichloromethane to a 100mL three-necked flask, 35℃ water bath, add 50g polylactic acid, stir at 600r / min for 1.5h to dissolve, add 6g acrylate emulsion, 0.5g quaternary ammonium salt modified montmorillonite, stir at 500r / min for 30min, add 0.8g anhydrous ethanol, continue to stir for 10min, get organic phase matrix;

[0051] Add 20g interfacial modified silica, 0.2g cellulose nanocrystal, stir at 400r / min for 20min at 30℃, get slurry, pour into 300mm×300mm×10mm mold, stand for 3h in 25℃, 60%RH constant temperature and humidity box;

[0052] Put the mold into the air drying oven, dry at 40℃ for 4h, solidify at 60℃ for 3h, solidify at 70℃ for 2h, naturally cool to room temperature, demold, get the sample.

[0053] Example 2.

[0054] The amount of polylactic acid is 55g, the amount of acrylate emulsion is 8g, the amount of silica particles is 22g, the amount of silane coupling agent KH-560 is 0.77g, the amount of hexadecyltrichlorosilane is 0.33g, the amount of polyethylene glycol PEG-400 is 1.43g, the amount of propylene glycol is 1.43g, the amount of acrylate monomer is 0.99g, the amount of sodium-based montmorillonite is 0.65g, the amount of cetyltrimethylammonium bromide is 0.29g, the amount of dichloromethane is 3g, and the amount of cellulose nanocrystal is 0.3g; The rest of the operation is the same as example 1.

[0055] Example 3.

[0056] The polylactic acid is 60 g, the acrylate emulsion is 10 g, the silica particles are 25 g, the silane coupling agent KH-560 is 1.05 g, the hexadecyl trichlorosilane is 0.45 g, the polyethylene glycol PEG-400 is 1.75 g, the propylene glycol is 1.75 g, the acrylate monomer is 1.25 g, the sodium montmorillonite is 0.91 g, the cetyltrimethylammonium bromide is 0.50 g, the dichloromethane is 4 g, and the cellulose nanocrystal is 0.4 g; the remaining operations are the same as those in Example 1.

[0057] Comparative Example 1.

[0058] (1) Take 22 g of silica particles, add 51.3 g of anhydrous ethanol, stir at 500 r / min for 10 min, add 3 g of KH-560, and stir at 35°C constant temperature water bath 300 r / min for 1 h to obtain KH-560 modified silica.

[0059] (2) The same as Example 2.

[0060] (3) The same as Example 2.

[0061] Comparative Example 2.

[0062] Use unmodified sodium montmorillonite instead of quaternary ammonium salt modified montmorillonite, and the remaining raw materials and steps are the same as those in Example 2.

[0063] Comparative Example 3.

[0064] No cellulose nanocrystal, and the remaining raw materials and steps are the same as those in Example 2.

[0065] Effect Example.

[0066] 1. Moisture permeability test:

[0067] Cut 100 mm x 100 mm samples from each of the example and comparative sample samples, wipe the surface with anhydrous ethanol, and place in a 23°C, 50%RH environment for 24h;

[0068] Add anhydrous calcium chloride to the moisture permeable cup, cover the sample on the cup opening, and fix it with a sealing rubber ring to ensure that there is no gap between the sample and the cup opening;

[0069] Put the assembled moisture permeable cup into a constant temperature and humidity chamber, set the temperature to 23°C and the relative humidity to 85%, and the humidity in the cup is maintained at 0%~5% by anhydrous calcium chloride, forming a stable humidity difference;

[0070] Every 24 h, the moisture permeable cup was taken out, the surface condensate water was absorbed with filter paper, and was accurately weighed (accuracy 0.001 g). The moisture permeability rate was calculated by the last data when the difference between the adjacent two times was less than or equal to 0.005 g = △m x 10 4 / (A x t), wherein △m was the total mass difference before and after the test (g), A was the effective test area (m 2 ), and t was the test time (h).

[0071] 2. Thermal conductivity test:

[0072] The sample of 300 mm x 300 mm x 10 mm was placed in a 105℃ oven for drying for 4 h, and after cooling to room temperature, the thickness of the sample at different positions was measured with a micrometer.

[0073] The protective hot plate heat meter was turned on, the cold plate temperature was set to 23℃, the hot plate temperature was set to 33℃, and the instrument temperature was stable. The sample was placed flat between the cold plate and the hot plate, a pressure of 0.02 MPa was applied, the test was started, the thermal conductivity was automatically calculated, and the average value was taken by parallel testing for 3 times.

[0074] 3. Mildew resistance test:

[0075] Black aspergillus and yellow aspergillus were selected, mixed at a volume ratio of 1:1, and a bacterial suspension with a concentration of 1 x 10 6 CFU / mL was prepared;

[0076] The sample of 50 mm x 50 mm was cut, sterilized with a UV lamp for 30 min, and placed in a sterile culture dish;

[0077] 0.2 mL of the bacterial suspension was taken with a pipette and evenly dropped on the surface of the sample, and a sterile glass sheet was covered (to avoid loss of the bacterial solution). The culture dish was placed in a constant temperature and humidity incubator, the temperature was set to 28℃, the relative humidity was set to 90%, and the culture was carried out for 28 days;

[0078] After the culture was completed, the mold coverage area on the surface of the sample was observed, and the standard rating was as follows: 0 level (no mold growth), 1 level (mold coverage area ≤ 10%), 2 level (10% < coverage area ≤ 30%), 3 level (30% < coverage area ≤ 60%), and 4 level (coverage area > 60%).

[0079] 4. Cold and hot cycle stability test:

[0080] The sample of 200 mm x 200 mm was cut, and the initial thermal conductivity λ0was tested.

[0081] The sample was placed in a high and low temperature test chamber, and the cycle program was set as follows: constant temperature at -10℃ for 2 h → heating to 50℃ → constant temperature at 50℃ for 2 h → cooling to -10℃, and one cycle was completed; a total of 100 cycles were carried out.

[0082] After the cycle, the sample was placed in a 23℃, 50%RH environment for 24h, and the thermal conductivity was retested (recorded as λ1), and the thermal conductivity increase (%) = (λ1-λ0) / λ0×100% was calculated.

[0083] 5. Appearance and bulk density test:

[0084] The sample surface was observed by naked eye for defects such as cracking, delamination, bubbles, etc., and the defect position and extent were recorded;

[0085] A 100mm×100mm×10mm sample was weighed (m, accurate to 0.01g) with an electronic balance, and the length (L), width (W), and thickness (H) were measured (all accurate to 0.1mm) with a vernier caliper, and the bulk density was calculated.

[0086] The above test results are shown in Table 1.

[0087] Table 1

[0088]

[0089] Obviously, the above examples are merely examples for clarity, and are not limitations on the embodiments. Based on the above description, other different forms of changes or variations can be made by those of ordinary skill in the art. All embodiments need not and cannot be exhaustively enumerated. The obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A high moisture permeable low thermal conductive wall material, characterized by, Comprise the following components by mass fraction: Polylactic acid, 50~60 parts; acrylate emulsion, 6~10 parts; Interface modification of silica, 20~25 parts; Quaternary ammonium salt modified montmorillonite, 0.5~1 parts; dichloromethane, 2~4 parts; cellulose nanocrystal, 0.2~0.4 parts; The interface modification of silica is based on silica particles, which are coated with a bottom inner layer composed of silane coupling agent KH-560 and hexadecyltrichlorosilane, a middle layer composed of polyethylene glycol PEG-400 and propylene glycol, and an outer layer composed of acrylic monomer from inside to outside; The quaternary ammonium salt modified montmorillonite is based on sodium-based montmorillonite, which is modified by ion exchange with hexadecyltrimethylammonium bromide; The specific preparation process of the interface modification of silica includes: Silica particles are added to anhydrous ethanol and ultrasonically dispersed to form a silica dispersion liquid with a concentration of 30%~35%; Silane coupling agent KH-560 and hexadecyltrichlorosilane are added to anhydrous ethanol and stirred to dissolve, then ultrasonic atomization is used to spray on the surface of the silica dispersion liquid, and after spraying, stirring is carried out in a 35℃ constant temperature water bath to form an inner layer; PEG-400 and propylene glycol are added to anhydrous ethanol and stirred to dissolve, then ultrasonic atomization is used to spray on the surface of the inner layer modified silica, and then stirring is carried out in a 40℃ constant temperature water bath to form a middle layer; Acrylate monomer is added to the above system and ultrasonically dispersed to form an outer layer.

2. The high moisture permeable low thermal conductive wall material according to claim 1, wherein, The number average molecular weight of the polylactic acid is 80000~100000 Da, the solid content of the acrylate emulsion is 45~50%, and the particle size of the silica particles is 1~3μm.

3. The high moisture permeable low thermal conductive wall material according to claim 1, wherein, The mass ratio of silane coupling agent KH-560 to hexadecyltrichlorosilane is 7:3, and the total mass of the two is 5%~6% of the mass of the silica particles.

4. The high moisture permeable low thermal conductive wall material according to claim 1, wherein The mass ratio of PEG-400 to propylene glycol is 1:1, and the total mass of the two is 6%~7% of the mass of the silica particles; the mass of the acrylate monomer is 4%~5% of the mass of the silica particles.

5. The high moisture permeable low thermal conductive wall material according to claim 1, wherein The specific preparation process of the quaternary ammonium salt modified montmorillonite includes: Sodium-based montmorillonite is weighed and added to deionized water and stirred to disperse, forming a montmorillonite suspension with a mass concentration of 5%; hydrochloric acid is added dropwise to the suspension to adjust the pH to 3~4; after ultrasonic treatment, the upper layer of the suspension is taken and reserved; Hexadecyltrimethylammonium bromide is weighed and dissolved in a 60℃ constant temperature water bath to prepare a quaternary ammonium salt solution with a concentration of 0.12mol / L; The upper layer of the suspension is heated to 60℃, continuously stirred, and the quaternary ammonium salt solution is added dropwise, then the system is continuously stirred for 4h at the same temperature; The mixed system is centrifuged to separate the supernatant; after repeated ethanol precipitation, vacuum drying, grinding and sieving, the quaternary ammonium salt modified montmorillonite is obtained.

6. The high moisture permeable low thermal conductive wall material according to claim 5, wherein, The mass ratio of sodium-based montmorillonite to hexadecyltrimethylammonium bromide is 10:3.5~5.

5.

7. A method of producing a high moisture permeable low thermal conductive wall material as claimed in any one of claims 1 to 6, characterized by, The steps include: S1, dichloromethane is added to a container, polylactic acid, acrylate emulsion, and quaternary ammonium salt modified montmorillonite are added and stirred to form a uniform organic phase matrix; S2, the interface modification silica, cellulose nanocrystals are added to the organic phase matrix, stirring and mixing, forming a uniform slurry system; the slurry is poured into the mold, placed in a constant temperature and humidity environment, and left to stand; S3, the mold is transferred into a forced air drying oven, and after temperature curing, it is naturally cooled to room temperature, demolded, and a high moisture permeable and low thermal conductivity wall material is obtained.

8. The method of claim 7, wherein the high-moisture-permeable low-thermal-conductive wall material is prepared by mixing the water-repellent material and the water-absorbing material in a weight ratio of 1 : 1 to 1 :

3. The temperature of the constant temperature and humidity environment in step S2 is 25°C, and the relative humidity is 60%.

9. The method of claim 7, wherein the high-moisture-permeable low-thermal-conductive wall material is prepared by mixing the water-repellent material and the water-absorbing material in a weight ratio of 1 : 1 to 1 :

3. In step S3, the temperature curing is specifically: first drying at 40°C for 4h; then the temperature is raised to 60°C, and the temperature is kept for 3h; then the temperature is raised to 70°C, and the temperature is kept for 2h.

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