A heat-insulating and moisture-retaining curing film and its preparation method and application

Abstract

The present invention discloses a thermal insulation and moisture-retaining curing film, a preparation method and application thereof, comprising a matrix layer, a hydrophilic layer and a hydrophobic layer which are sequentially stacked; the raw materials for preparing the matrix layer include straw fibers; the raw materials for preparing the hydrophilic layer include hydrophilic silane and filler; the raw materials for preparing the hydrophobic layer include polyester elastomer and hydrophobic silane. The thermal insulation and moisture-retaining curing film of the present invention has an elastic structure which is hydrophobic on the outside and hydrophilic on the inside. While improving the mechanical properties of the thermal insulation and moisture-retaining curing film, the porosity of the thermal insulation and moisture-retaining curing film is reduced, thereby effectively preventing the evaporation of water in concrete and improving the thermal insulation and moisture-retaining effect of the thermal insulation and moisture-retaining curing film.

Description

Technical Field

[0001] The present invention belongs to the field of biodegradable thermal insulation and moisture-retaining curing films, and in particular relates to a thermal insulation and moisture-retaining curing film, a preparation method thereof, and an application thereof. Background Art

[0002] After concrete is poured, water can evaporate too quickly, causing dehydration. This prevents the gelled cement particles from fully hydrating and transforming into stable crystals, resulting in a lack of adhesion. This can lead to flaking or powdery shedding on the concrete surface. Furthermore, when the concrete has not yet achieved sufficient strength, premature evaporation can cause significant shrinkage and cracking. Therefore, initial post-pour curing is crucial. Common concrete curing methods include: water spraying, curing with curing agents, scaffolding, and thermal storage. Water spraying is a natural curing method, primarily consisting of spray curing and surface water flow. Spray curing typically uses a mist of water, not a stream, and does not directly pressurize the concrete surface. It is suitable for projects with complex structures and meticulous curing. Stream curing uses a stream of water covering the concrete surface. The water flow should be minimal, preventing it from scouring the concrete surface and causing spalling damage. Experience in some projects has shown that stream curing effectively reduces the surface temperature of the concrete and prevents cracking. With the needs of social development, a large number of complex concrete structures have emerged. The surface of the structures is irregular, the surface area is increased, and water evaporates easily. This makes it difficult to maintain a continuous moist state on the concrete surface during watering curing in actual engineering applications, and the effect of watering curing is poor. At the same time, watering curing is accompanied by a serious waste of water resources. For some projects located in remote areas, local water resources are scarce, and the cost of water supply curing is high, so watering curing is not suitable. Cover curing agent curing is a natural curing method. A curing agent containing a polymer solution is sprayed on the concrete surface. After the solution evaporates, a continuous, impermeable, and sealed film is quickly formed on the concrete surface. The film accumulates most of the water lost in the concrete for self-cure. The film has a long shelf life and can provide good curing for the concrete. Curing with curing agents is suitable for concrete in high-altitude buildings and in arid and water-scarce areas that are difficult to maintain with watering or covering methods. However, it has high construction requirements and is easily affected by missed brushing, missed spraying, and uneven application. It also affects the bonding performance between new and old concrete, and the toughness of the film is greatly affected by the spraying thickness. The curing effect in complex weather environments is unclear. Scaffolding curing is a type of heating curing and is suitable for curing concrete that requires wind protection, heat insulation, and sun shading, or in low-temperature environments with an average daily temperature of -15°C to -10°C. Warmhouse curing can be based on scaffolding curing and incorporates radiators, exhaust pipes, electric heaters, or stoves to heat the air in the shed, allowing the concrete to be cured in an environment above zero degrees. However, scaffolding curing is more cumbersome to construct, occupies construction resources, has high costs, and has a low turnover rate, resulting in a small scope of application. Thermal storage curing is a type of heating curing. After the concrete is poured, the heat generated by its own hydration reaction and external insulation measures are used to delay cooling, so that the concrete reaches the expected strength when it cools to below zero.The thermal storage curing method is simple, does not require concrete heating equipment, can save energy, has low cost, and improves the durability of concrete, but it has stricter requirements on construction measures.

[0003] Therefore, there is an urgent need to prepare a curing film that can solve the problem of poor thermal insulation and moisture retention in concrete curing. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. To this end, the present invention proposes a heat-insulating and moisturizing curing film, comprising a matrix layer, a hydrophilic layer and a hydrophobic layer stacked in sequence, wherein the hydrophilic layer is first coated on the outside of the matrix layer made of straw fiber and then the hydrophobic layer is coated, so that the heat-insulating and moisturizing curing film has an elastic structure that is hydrophobic on the outside and hydrophilic on the inside. While improving the mechanical properties of the heat-insulating and moisturizing curing film, the porosity of the heat-insulating and moisturizing curing film is reduced, effectively preventing the evaporation of water in the concrete, and improving the heat-insulating and moisturizing effect of the heat-insulating and moisturizing curing film. The hydrophilic layer of the present invention ensures the moisture of the concrete surface, allowing water to penetrate into the surface. In the capillary pores of the surface concrete, a chemical reaction occurs to form a colloidal substance, which enables the concrete surface to densify in a relatively short period of time. It can play a role in preventing cracks and shrinkage in the hardening concrete stage. The hydrophobic layer blocks the pores and water absorption channels inside the concrete, thereby giving the autoclaved aerated concrete board a self-hydrophobic property, greatly enhancing the waterproofness of the autoclaved aerated concrete board. In addition, the membrane properties of the first hydrophobic admixture are also beneficial to improving the toughness of the autoclaved aerated concrete board, improving the product performance of the autoclaved aerated concrete board, and improving the maintenance effect.

[0005] The second aspect of the present invention provides a method for preparing the above-mentioned heat-insulating and moisture-retaining curing film.

[0006] The third aspect of the present invention provides an application of the above-mentioned curing membrane in the field of concrete curing.

[0007] According to an embodiment of the first aspect of the present invention, a heat-insulating and moisture-retaining curing film is provided, comprising a matrix layer, a hydrophilic layer, and a hydrophobic layer stacked in sequence;

[0008] The raw materials for preparing the matrix layer include straw fibers;

[0009] The raw materials for preparing the hydrophilic layer include hydrophilic silane and filler;

[0010] The raw materials for preparing the hydrophobic layer include polyester elastomer and hydrophobic silane.

[0011] The embodiments according to the first aspect of the present invention have at least the following beneficial effects:

[0012] The matrix layer, made from straw fiber, is inexpensive and easily degradable. The matrix layer is coated with a hydrophilic layer and then a hydrophobic layer. On the one hand, the hydrophilic layer swells in conjunction with the filler after absorbing water, improving the gas barrier properties, which helps prevent microbial erosion and enhances the thermal insulation effect of the curing film. The polyurethane resin in the hydrophobic layer has a chain structure composed of hard segments (composed of isocyanates and small molecule chain extenders) and soft segments (oligomer polyols), which determines its unique properties of being both hard and flexible. This effectively improves the mechanical properties of the thermal and moisture-insulating curing film while preventing rainwater erosion with the help of hydrophobic silane, ensuring the gas barrier properties of the hydrophilic layer and enhancing the thermal insulation effect of the curing film.

[0013] According to some embodiments of the present invention, the polyester elastomer includes Wanhua 8539.

[0014] According to some embodiments of the present invention, the straw fiber comprises fermented straw fiber.

[0015] According to some embodiments of the present invention, the hydrophobic silane includes at least one of n-octyltrimethoxysilane, isooctyltriethoxysilane and n-dodecyltrimethoxysilane.

[0016] According to some embodiments of the present invention, the hydrophilic silane includes at least one of γ-glycidyloxypropyltrimethoxysilane and β-(3,4-epoxycyclohexyl)-ethyltriethoxysilane.

[0017] According to some embodiments of the present invention, the filler includes at least one of mica, talc, hydrotalcite-like material, glass beads, quartz, chlorite, epidote, calcium carbonate, feldspar, olivine, garnet and andalusite.

[0018] The volume of the above-mentioned filler expands after absorbing water, effectively filling the pores in the straw fiber-based thermal insulation and moisturizing curing film, making the fiber network more dense, and blocking the diffusion of gas or liquid molecules, so that the straw fiber-based thermal insulation and moisturizing curing film has an excellent gas barrier effect and reduces the water vapor permeability of the inner layer.

[0019] In some embodiments of the present invention, the raw materials for preparing the hydrophobic layer further include: an alkaline catalyst; the alkaline catalyst includes: at least one of potassium silicate, lithium silicate and potassium methyl silicate.

[0020] In some embodiments of the present invention, the raw materials for preparing the hydrophilic layer further include: an acidic catalyst; the acidic catalyst includes: at least one of an inorganic acid and a water-soluble organic acid.

[0021] In some preferred embodiments of the present invention, the inorganic acid includes at least one of hydrochloric acid and phosphoric acid.

[0022] In some preferred embodiments of the present invention, the water-soluble organic acid includes: acetic acid.

[0023] According to an embodiment of the second aspect of the present invention, a method for preparing a heat-insulating and moisture-retaining curing film is provided, the method comprising the following steps:

[0024] S1: hydrolyzing the hydrophilic silane to obtain a hydrophilic silane hydrolyzate and applying it to the surface of the substrate layer to obtain a composite layer;

[0025] S2: mixing the polyester elastomer and the hydrophobic silane to react to obtain a modified dispersion 1;

[0026] S3: Mixing the modified dispersion 1 obtained in step S2 with the composite layer obtained in step S1.

[0027] According to some embodiments of the present invention, in step S2, the mass ratio of the polyester elastomer to the hydrophobic silane is 1:(0.05-0.1).

[0028] According to some embodiments of the present invention, in step S2, the mixing time is 0.5-1 h.

[0029] In some embodiments of the present invention, in step S2, the mixing speed is 2000-5000 r / min.

[0030] In some embodiments of the present invention, step S2 further includes adding the alkaline catalyst between the mixing and the reaction.

[0031] In some embodiments of the present invention, in step S2, the pH value of the reaction is 8-10.

[0032] In some embodiments of the present invention, in step S1, the hydrolysis is accompanied by stirring; the stirring speed is 200-500 r / min.

[0033] In some embodiments of the present invention, in step S1, the hydrolysis further comprises adding the acidic catalyst.

[0034] In some embodiments of the present invention, in step S1, the pH value of the hydrolysis is 5-6.

[0035] In some embodiments of the present invention, in step S1, the reaction time of the hydrolysis is 1-2 hours.

[0036] In some embodiments of the present invention, in step S3, the mass ratio of the modified dispersion 1 to the hydrophilic silane hydrolyzate is 1:(0.075-0.125).

[0037] In some preferred embodiments of the present invention, in step S3, the mass ratio of the modified dispersion 1 to the hydrophilic silane hydrolyzate is 1:(0.085-0.105).

[0038] In some embodiments of the present invention, in step S3, the mixing speed is 300-500 r / min.

[0039] In some embodiments of the present invention, in step S3, the mixing time is 2-3 hours.

[0040] According to an embodiment of the third aspect of the present invention, an application of a curing membrane in the field of concrete curing is proposed. Specific embodiments

[0041] The following will clearly and completely describe the concept and technical effects of the present invention in conjunction with the embodiments to fully understand the purpose, features and effects of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative work are all within the scope of protection of the present invention.

[0042] Example 1

[0043] This embodiment prepares a heat-insulating and moisturizing curing film, and the specific steps are as follows:

[0044] S1. In parts by mass, at room temperature, 50 parts of montmorillonite, 70 parts of γ-glycidyloxypropyltrimethoxysilane and 80 parts of deionized water were mixed in a disperser, the speed was controlled at 300 r / min, hydrochloric acid was added as an acidic catalyst to control the pH value of the mixture to 5-6, and the reaction was carried out for 1 h to obtain a hydrophilic silane hydrolyzate;

[0045] S2. The fermented straw fiber, sizing agent, and retention aid are uniformly mixed in an aqueous system, vacuum-molded using a vacuum molding device, and then dried using a heat-insulating and moisture-retaining film drying device at a temperature of 103±2°C to produce a matrix layer; the hydrolyzate obtained in step S1 is applied to the matrix layer to form a composite layer;

[0046] S3. In parts by mass, at room temperature, 150 parts of polyester elastomer were dispersed in a homogenizer at a speed of 2500 r / min. Then, 5 parts of n-octyltrimethoxysilane were slowly added, and the addition time was controlled to be 15 minutes. After completion, the mixture was stirred at the same speed for 1 hour. The speed was then reduced to 800 r / min, and potassium methyl silicate alkaline catalyst was added. The pH value of the mixture was controlled to be 8-10. The mixture was reacted for 0.5 hour to obtain a modified dispersion 1, which was then applied to the composite layer obtained in step S2 to obtain a heat-insulating and moisture-retaining curing film.

[0047] Example 2

[0048] This embodiment prepares a heat-insulating and moisture-retaining curing film. Compared with Example 2, the difference is that calcium carbonate replaces the montmorillonite in Example 1, and the other conditions are the same.

[0049] Example 3

[0050] This embodiment prepares a heat-insulating and moisture-retaining curing film. Compared with Example 2, the difference is that chlorite replaces the montmorillonite in Example 1, and the other conditions are the same.

[0051] Example 4

[0052] This embodiment prepares a heat-insulating and moisture-retaining curing film. Compared with Example 2, the difference is that mica stone replaces the montmorillonite in Example 1, and the other conditions are the same.

[0053] Comparative Example 1

[0054] In this comparative example, a heat-insulating and moisture-retaining curing film is prepared: compared with Example 1, the preparation method described in this comparative example does not include the hydrophilic layer in Example 1, and the rest of the process is the same as that in Example 1.

[0055] Comparative Example 2

[0056] In this comparative example, a heat-insulating and moisture-retaining curing film is prepared: compared with Example 1, the preparation method described in this comparative example does not include the hydrophobic layer in Example 1, and the rest of the process is the same as that in Example 1.

[0057] Comparative Example 3

[0058] In this comparative example, a heat-insulating and moisture-retaining curing film is prepared: compared with Example 1, the preparation method described in this comparative example does not include the montmorillonite in Example 1, and the rest of the process is the same as that in Example 1.

[0059] Test Example 1

[0060] After the same batch of concrete was formed, the membranes of the embodiment and the comparative example were covered on the surface of the concrete in an outdoor environment with an average outdoor temperature of not less than -10°C. After 5 days of the same curing treatment and repeated use effect evaluation, the results shown in Table 1 were obtained:

[0061] Table 1 Performance test results of the heat preservation and moisture retention curing films obtained in Examples and Comparative Examples

[0062]

[0063]

[0064] As can be seen from Table 1, the thermal insulation and moisturizing curing films prepared in Examples 1 to 4 have an elastic structure that is hydrophobic on the outside and hydrophilic on the inside. While improving the mechanical properties of the thermal insulation and moisturizing curing films, the porosity of the thermal insulation and moisturizing curing films is reduced, effectively preventing the evaporation of water in the concrete, and improving the thermal insulation and moisturizing effect of the thermal insulation and moisturizing curing films. Comparative Example 1 does not include the hydrophilic layer in Example 1, so it cannot cooperate with the filler to swell after absorbing water, cannot improve the gas barrier properties, and the thermal insulation effect is reduced. Comparative Example 2 does not include the hydrophobic layer in Example 1, so the mechanical properties of the thermal insulation and moisturizing curing film are reduced and the moisturizing properties of the thermal insulation and moisturizing curing film cannot be improved. Comparative Example 3 does not include montmorillonite, so it cannot swell after absorbing water, cannot improve the gas barrier properties of the thermal insulation and moisturizing curing film, and the thermal insulation effect is reduced.

[0065] While the embodiments of the present invention have been described in detail above, the present invention is not limited to the embodiments described above. Various modifications may be made within the scope of knowledge possessed by a person skilled in the art without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof may be combined with one another unless there is a conflict.

Claims

1. A heat-insulating and moisturizing curing film, characterized in that: It comprises a matrix layer, a hydrophilic layer and a hydrophobic layer which are stacked in sequence; The raw materials for preparing the matrix layer include straw fibers; The raw materials for preparing the hydrophilic layer include hydrophilic silane and filler; The raw materials for preparing the hydrophobic layer include polyester elastomer and hydrophobic silane; The hydrophobic silane comprises at least one of n-octyltrimethoxysilane, isooctyltriethoxysilane and n-dodecyltrimethoxysilane; The hydrophilic silane comprises at least one of γ-glycidyloxypropyltrimethoxysilane and β-(3,4-epoxycyclohexyl)-ethyltriethoxysilane; The filler includes at least one of montmorillonite, mica, talc, hydrotalcite-like, glass microbeads, quartz, chlorite, epidote, calcium carbonate, feldspar, olivine, garnet and andalusite.

2. The curing film according to claim 1, characterized in that: The straw fiber includes fermented straw fiber.

3. The method for preparing a curing film according to claim 1 or 2, characterized in that: The preparation method comprises the following steps: S1: hydrolyzing the hydrophilic silane to obtain a hydrophilic silane hydrolyzate and applying it to the surface of the substrate layer to obtain a composite layer; S2: mixing the polyester elastomer and the hydrophobic silane to react to obtain a modified dispersion 1; S3: Mixing the modified dispersion 1 obtained in step S2 with the composite layer obtained in step S1.

4. The preparation method according to claim 3, characterized in that The mass ratio of the polyester elastomer to the hydrophobic silane in step S2 is 1:(0.05-0.1).

5. The preparation method according to claim 4, characterized in that In step S2, the mixing time is 0.5-1 h.

6. The preparation method according to claim 3, characterized in that The mass ratio of the modified dispersion to the hydrophilic silane hydrolyzate is 1:(0.075-0.125).

7. Use of the thermal insulation and moisture retention curing film according to claim 1 or 2 in the field of concrete curing.

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