A sealant for fabricated building and a preparation method thereof

Abstract

The present application relates to the technical field of sealant, and provides a kind of assembly type building sealant and preparation method thereof, comprising the following weight parts of raw material components: alkyl modified polyaspartic ester resin 100~140 parts, plasticizer 20~40 parts, reinforcing filler 80~140 parts, auxiliary 2.5~6.5 parts, silane coupling agent 2~7 parts, catalyst 1~2.5 parts.The assembly type building sealant prepared by the present application can withstand long time wind and sunshine, has good adhesion, good durability, long service life, and solves the problem of insufficient adhesion or weather resistance of the existing assembly type building sealant.

Description

Technical Field

[0001] This invention relates to the field of sealant technology, and in particular to a sealant for prefabricated buildings and its preparation method. Background Technology

[0002] Prefabricated buildings are constructed by transporting prefabricated building components and accessories from a factory to the construction site and assembling them on-site using reliable connection methods. Compared to traditional buildings, prefabricated buildings offer numerous advantages, including high construction efficiency, low energy consumption, less environmental pollution, and high equipment turnover. However, on-site assembly leaves numerous joint gaps, creating defects in waterproofing and sealing. Furthermore, exterior wall panels, being on the building's facade, are directly exposed to the atmospheric environment, and are affected by conventional environmental factors such as temperature, humidity, and sunlight, as well as uncontrollable factors like earthquakes and acid rain. Therefore, sealant is a crucial guarantee for the waterproofing of exterior wall panels in prefabricated buildings, and its performance directly impacts the building's lifespan and other performance characteristics. Thus, the selection of sealant should be based on the following factors.

[0003] First, adhesive compatibility. Currently, most prefabricated building panels on the domestic market are made of concrete, a random porous alkaline material that is not conducive to the adhesion of sealants. Therefore, when selecting a sealant, the adhesive compatibility between the sealant and the concrete wall panel must be considered. Second, weather resistance. When used for sealing joints in prefabricated building exterior wall panels, the sealant is completely exposed to the outdoor environment. Under the influence of wind, rain, and ultraviolet radiation, the sealant is prone to aging and deformation. Therefore, the selected sealant must have good weather resistance.

[0004] Currently, the main products used in this field are silicone-modified polyether resin sealants (MS sealants) and ketoxime-type silicone sealants. For example, patent application number CN202110073764.3 discloses an MS sealant and its preparation method, which, by mass, includes the following components: 15-40 parts of α-silane-modified polyether resin, wherein the α-silane-modified polyether resin is obtained by polymerization reaction of α-isocyanate-based silane and polyether polyol; 15-25 parts of plasticizer, wherein the plasticizer is a first polyether polyol and / or diisononyl cyclohexane 1,2-dicarboxylate, and the weight average molecular weight of the first polyether polyol is <4000; 1-5 parts of dehydrating agent; 30-50 parts of nano-calcium carbonate; 1-15 parts of thixotropic agent; 0.1-1 part of stabilizer; and 0.5-3 parts of adhesion promoter. Although MS sealant combines the advantages of silicone sealant and polyurethane sealant, with good adhesion, flexibility and coatability, its overall bond energy is relatively low, and chemical bonds are prone to breakage under long-term ultraviolet light irradiation.

[0005] For example, patent application number CN202010598016.2 discloses a deoxime-type silicone sealant for construction, which is prepared from raw materials including the following components: 20-70 parts by weight of base polymer; 70-130 parts by weight of reinforcing filler; 0-5 parts by weight of functional filler; 2-12 parts by weight of crosslinking agent; 0-2 parts by weight of tackifier; and 0.05-0.5 parts by weight of catalyst; wherein the base polymer is α,ω-dihydroxypolydimethylsiloxane; and the viscosity of the base polymer at 25°C is 1000-300000 mPa·s. Compared with existing technologies, the oxime-free silicone sealant for construction provided by this invention uses a specific content of components to achieve better interaction. The resulting oxime-free silicone sealant for construction has a clay-like consistency, can be used directly without tools such as a glue gun, can be hand-shaped, is easy to use, and has a large initial tack, can bond and set instantly, and has good insulation and flame retardancy. It can be used in the construction and household fields as a nail-free sealant, for filling gaps, or for other sealing and bonding applications, and is safe and reliable. Due to its high silicon content, the oxime-free silicone sealant has good weather resistance; however, the higher the silicon content, the closer it is to an inorganic material, and the greater the internal stress, the easier it is for the adhesion to weaken during alternating hot and cold cycles.

[0006] Furthermore, when sealants are used as joint sealants for exterior wall panels, they may encounter the following situations: drying shrinkage and thermal expansion and contraction of precast concrete slabs; slab displacement caused by wind loads and earthquakes; and settlement displacement caused by foundation settlement. Therefore, sealants for prefabricated building exterior wall panels must possess good displacement resistance and displacement tracking ability. In other words, sealants for prefabricated buildings must have a certain degree of elasticity and a certain capacity for free expansion and contraction deformation. Generally, tensile modulus characterizes the flexibility of sealant; the lower the tensile modulus, the softer the sealant, and the smaller the internal stress when the same deformation occurs. Generally, the tensile modulus of prefabricated sealants is required to not exceed 0.4 MPa, and the Shore hardness should not exceed A15. Currently, there are few reports on sealants with polyaspartic acid ester resin and its derivatives as the main components. After searching, only patent numbers CN202110461723 and CN201410076892 disclose polyaspartic acid ester type sealants. However, the performance test results of the embodiments in the two patent documents show that the provided sealant is a high-modulus sealing material with high Shore hardness, which is not suitable for bonding and sealing gaps in prefabricated buildings. Moreover, the existing polyaspartic acid ester type sealant is a two-component sealant, and the A and B components need to be weighed and mixed on-site, with a short pot life, which brings inconvenience to construction and is prone to quality problems. Summary of the Invention

[0007] Therefore, one of the objectives of this invention is to provide a sealant for prefabricated buildings, addressing the problems of insufficient adhesion or weather resistance in existing sealants for prefabricated buildings.

[0008] Another object of the present invention is to provide a method for preparing the sealant for prefabricated buildings.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] A sealant for prefabricated buildings comprises the following raw material components in parts by weight: 100-140 parts of alkyl-modified polyaspartic acid ester resin, 20-40 parts of plasticizer, 80-140 parts of reinforcing filler, 2.5-6.5 parts of additives, 2-7 parts of silane coupling agent, and 1-2.5 parts of catalyst.

[0011] The alkyl-modified polyaspartic acid ester resin is prepared by the following method:

[0012] (1) Add the amine resin to a high-pressure reactor equipped with a stirrer and a thermometer. Under stirring, slowly add unsaturated dicarboxylic acid ester and unsaturated monocarboxylic acid ester, maintain the temperature at 40-50℃, raise the temperature to 90-100℃ after the addition is completed, keep the temperature for 12-15h, and then lower the temperature to below 40℃ to obtain polyaspartic acid ester resin. The mass ratio of the amine resin, unsaturated dicarboxylic acid ester and unsaturated monocarboxylic acid ester is 100-150:160-250:0-50.

[0013] (2) Evacuate the vacuum and control the vacuum degree at 100-300 Pa. Then turn on the stirrer and introduce nitrogen gas until the pressure inside the reactor is 3-5 kPa. Then slowly add the isocyanate coupling agent. The molar ratio of the isocyanate coupling agent to the polyaspartic acid ester resin is 2.01-2.05:1. React at 40-50°C for 10-15 h to obtain the alkyl-modified polyaspartic acid ester resin.

[0014] A further improvement is that the amine resin is any one of 4,4'-diaminodicyclohexylmethane and 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane, or a mixture of the two in any ratio.

[0015] A further improvement is that the unsaturated dicarboxylic acid ester is any one or more of diethyl maleate, dimethyl maleate, and dibutyl maleate mixed in any ratio.

[0016] A further improvement is that the unsaturated monocarboxylic acid ester is any one of alkyl acrylate and alkyl methacrylate, or a mixture of both in any ratio.

[0017] A further improvement is that the isocyanate coupling agent is any one of isocyanate-propyltrimethoxysilane and isocyanate-propyltriethoxysilane, or a mixture of both in any ratio.

[0018] A further improvement is that the reinforcing filler is any one of nano-calcium carbonate, fumed silica, or carbon black.

[0019] A further improvement is that the additives are dehydrating agents and ultraviolet absorbers, comprising 44-50% dehydrating agent and 50-56% ultraviolet absorber by mass percentage.

[0020] A further improvement is that the dehydrating agent is any one of vinyltrimethoxysilane and vinyltriethoxysilane, or a mixture of the two in any ratio.

[0021] A further improvement is that the silane coupling agent is any one of γ-aminopropyltriethoxysilane and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, or a mixture of the two in any ratio.

[0022] A further improvement is that the catalyst is an organotin catalyst or a titanate catalyst.

[0023] This invention also provides a method for preparing the above-mentioned sealant for prefabricated buildings, comprising the following steps:

[0024] S1. Weigh each raw material according to the predetermined weight and set aside;

[0025] S2. Add alkyl-modified polyaspartic acid ester resin, plasticizer, reinforcing filler, and additives to a planetary reactor. Dehydrate under vacuum at 110-130°C for 1-3 hours, then cool to below 50°C. Add silane coupling agent and catalyst, and stir under vacuum until homogeneous to obtain the required sealant for prefabricated buildings. Discharge the material and store it in a high-density polyethylene plastic tube.

[0026] By adopting the aforementioned technical solution, the beneficial effects of the present invention are as follows:

[0027] 1. Existing MS sealant uses a resin with a COC main chain structure, which has relatively low bond energy and is prone to chemical bond breakage under long-term ultraviolet light irradiation. The resin used in deketoxime type silicone sealant has a Si-O-Si main chain structure with high silicon content, thus exhibiting good weather resistance. However, higher silicon content leads to a closer resemblance to inorganic materials, increasing internal stress and causing adhesion degradation during alternating hot and cold cycles. Furthermore, high silicon content results in non-stick properties and low surface energy, meaning that further coloring is impossible, leading to poor decorative properties. The sealant for prefabricated buildings provided by this invention uses an N-CO-N main chain structure resin with high molecular symmetry, endowing it with excellent stability, durability, heat resistance, and abrasion resistance. The addition reaction introduces Si-O bonds into the alkyl-modified polyaspartic acid ester resin structure, increasing the overall bond energy and further improving durability.

[0028] 2. Existing polyaspartic acid ester sealants use a polymer compound formed by the reaction of polyaspartic acid ester resin and isocyanate curing agent as the film-forming substance, which is then combined with other components to form the desired film. The isocyanate used is diisocyanate or polyisocyanate, which has high functionality and can only be processed into two-component products. Compared with the prior art, this invention employs a completely different curing mechanism, specifically as follows: Isocyanate-based propyltrimethoxysilane or isocyanate-based propyltriethoxysilane undergoes an addition reaction with polyaspartic acid ester resin to form a new resin—alkyl-modified polyaspartic acid ester resin. This only increases the viscosity of the entire system and does not gel. The siloxane functional group in the alkyl-modified polyaspartic acid ester resin molecular structure, when exposed to air after application, hydrolyzes to form Si-OH, which then condenses to form a Si-O-Si polymer, thereby curing into a film.

[0029] 3. Two-component sealant products require on-site weighing and mixing, and have a short pot life, causing inconvenience during construction. The prefabricated building sealant provided by this invention is a single-component product, which is easy to use and has good workability.

[0030] 4. The sealant prepared by this invention can withstand long-term exposure to wind and sun, exhibits good adhesion, durability, and a long service life. The preparation process produces no byproducts, is simple, uses readily available raw materials, and can be mass-produced. Detailed Implementation

[0031] The present invention is further illustrated below by way of examples, but these examples do not limit the invention to the scope of the embodiments described. All reagents and raw materials used in the following examples are commercially available, and test methods not specifically specified are generally performed under conventional conditions or according to the conditions recommended by the respective manufacturers.

[0032] Example 1

[0033] A sealant for prefabricated buildings comprises the following raw material components in parts by weight: 100 parts of alkyl-modified polyaspartic ester resin, 20 parts of plasticizer, 80 parts of nano-calcium carbonate, 2.5 parts of additives, 2 parts of γ-aminopropyltriethoxysilane, and 1 part of dibutyltin dilaurate. The additives include 44% vinyltrimethoxysilane and 56% ultraviolet absorber Tinuvin 326 by weight percentage.

[0034] The alkyl-modified polyaspartic acid ester resin is prepared by the following method:

[0035] (1) 4,4'-diaminodicyclohexylmethane was added to a high-pressure reactor equipped with a stirrer and a thermometer. Dimethyl maleate and dodecyl 2-acrylate were slowly added dropwise while stirring. The temperature was maintained at 40°C. After the addition was completed, the temperature was raised to 90°C and kept at that temperature for 15 hours. Then the temperature was lowered to below 40°C to obtain polyaspartic acid ester resin. The mass ratio of 4,4'-diaminodicyclohexylmethane, dimethyl maleate, and dodecyl 2-acrylate was 100:160:2.

[0036] (2) Evacuate the vacuum and control the vacuum degree at 100 Pa. Then turn on the stirrer and introduce nitrogen gas until the pressure inside the reactor is 3 kPa. Then slowly add 3-isocyanate-propyltrimethoxysilane and react at 40°C for 15 h to obtain alkyl-modified polyaspartic acid ester resin. The molar ratio of 3-isocyanate-propyltrimethoxysilane to polyaspartic acid ester resin is 2.01:1.

[0037] The preparation method of the above-mentioned sealant for prefabricated buildings includes the following steps:

[0038] S1. Weigh each raw material according to the predetermined weight and set aside;

[0039] S2. Add alkyl-modified polyaspartic acid ester resin, plasticizer, nano calcium carbonate, and additives to a planetary reactor. Dehydrate under vacuum at 110°C for 3 hours, then cool to below 50°C. Add γ-aminopropyltriethoxysilane and dibutyltin dilaurate, and stir under vacuum until homogeneous to obtain the required sealant for prefabricated buildings. Discharge the material and store it in a high-density polyethylene plastic tube.

[0040] During application, clean and prepare the areas where sealant will be applied. Observe the areas to be sealed, and if necessary, apply protective tape to the outer edge of the gap to prevent uneven width and maintain the overall appearance. Cut the sealant nozzle according to the size of the gap, place it on the special caulking gun, and fix it in place. When applying sealant, generally maintain a 45° angle, hold the caulking gun, apply even pressure, and smoothly apply sealant along the gap. After applying a section, wipe away excess sealant with your finger (or a special scraper), and carefully peel off the tape.

[0041] Example 2

[0042] A sealant for prefabricated buildings comprises the following raw material components in parts by weight: 140 parts of alkyl-modified polyaspartic ester resin, 40 parts of plasticizer, 140 parts of fumed silica, 6.5 parts of additives, 7 parts of N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, and 2.5 parts of tetrabutyl titanate. The additives, by mass percentage, include 50% vinyltriethoxysilane and 50% ultraviolet absorber Tinuvin 770DF.

[0043] The alkyl-modified polyaspartic acid ester resin is prepared by the following method:

[0044] (1) 4,4'-diaminodicyclohexylmethane was added to a high-pressure reactor equipped with a stirrer and a thermometer. Dibutyl maleate and octadecyl methacrylate were slowly added dropwise while stirring. The temperature was maintained at 40°C. After the addition was completed, the temperature was raised to 100°C and kept at that temperature for 12 hours. Then the temperature was lowered to below 50°C to obtain polyaspartic acid ester resin. The mass ratio of 4,4'-diaminodicyclohexylmethane, dibutyl maleate, and octadecyl methacrylate was 150:250:50.

[0045] (2) Evacuate the vacuum and control the vacuum degree at 300 Pa. Then turn on the stirrer and introduce nitrogen gas until the pressure inside the reactor is 5 kPa. Then slowly add 3-isocyanate-propyltrimethoxysilane and react at 50°C for 10 h to obtain alkyl-modified polyaspartic acid ester resin. The molar ratio of 3-isocyanate-propyltrimethoxysilane to polyaspartic acid ester resin is 2.05:1.

[0046] The preparation method of the above-mentioned sealant for prefabricated buildings includes the following steps:

[0047] S1. Weigh each raw material according to the predetermined weight and set aside;

[0048] S2. Add alkyl-modified polyaspartic acid ester resin, plasticizer, fumed silica, and additives to a planetary reactor. Dehydrate under vacuum at 130°C for 1 hour, then cool to below 50°C. Add N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane and tetrabutyl titanate, and stir under vacuum until homogeneous to obtain the required sealant for prefabricated buildings. Discharge the material and store it in a high-density polyethylene plastic tube.

[0049] During application, clean and prepare the areas where sealant will be applied. Observe the areas to be sealed, and if necessary, apply protective tape to the outer edge of the gap to prevent uneven width and maintain the overall appearance. Cut the sealant nozzle according to the size of the gap, place it on the special caulking gun, and fix it in place. When applying sealant, generally maintain a 45° angle, hold the caulking gun, apply even pressure, and smoothly apply sealant along the gap. After applying a section, wipe away excess sealant with your finger (or a special scraper), and carefully peel off the tape.

[0050] Example 3

[0051] A sealant for prefabricated buildings comprises the following raw material components in parts by weight: 120 parts of alkyl-modified polyaspartic ester resin, 30 parts of plasticizer, 100 parts of carbon black, 5 parts of additives, 5 parts of γ-aminopropyltriethoxysilane, and 2 parts of dibutyltin dilaurate. The additives include 48% vinyltrimethoxysilane and 52% ultraviolet absorber Tinuvin 326 by weight percentage.

[0052] The alkyl-modified polyaspartic acid ester resin is prepared by the following method:

[0053] (1) 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane was added to a high-pressure reactor equipped with a stirrer and a thermometer. Diethyl maleate and tetradecyl methacrylate were slowly added dropwise while stirring. The temperature was maintained at 45°C. After the addition was completed, the temperature was raised to 95°C and kept at that temperature for 14 hours. Then the temperature was lowered to below 40°C to obtain polyaspartic acid ester resin. The mass ratio of 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane, diethyl maleate, and tetradecyl methacrylate was 120:200:25.

[0054] (2) Evacuate the vacuum and control the vacuum degree at 200 Pa. Then turn on the stirrer and introduce nitrogen gas until the pressure inside the reactor is 4 kPa. Then slowly add 3-isocyanate-propyltriethoxysilane and react at 45°C for 12 h to obtain alkyl-modified polyaspartic acid ester resin. The molar ratio of 3-isocyanate-propyltriethoxysilane to polyaspartic acid ester resin is 2.03:1.

[0055] The preparation method of the above-mentioned sealant for prefabricated buildings includes the following steps:

[0056] S1. Weigh each raw material according to the predetermined weight and set aside;

[0057] S2. Add alkyl-modified polyaspartic acid ester resin, plasticizer, carbon black, and additives to a planetary reactor. Dehydrate under vacuum at 120°C for 2 hours, then cool to below 50°C. Add γ-aminopropyltriethoxysilane and dibutyltin dilaurate, and stir under vacuum until homogeneous to obtain the required sealant for prefabricated buildings. Discharge the material and store it in a high-density polyethylene plastic tube.

[0058] During application, clean and prepare the areas where sealant will be applied. Observe the areas to be sealed, and if necessary, apply protective tape to the outer edge of the gap to prevent uneven width and maintain the overall appearance. Cut the sealant nozzle according to the size of the gap, place it on the special caulking gun, and fix it in place. When applying sealant, generally maintain a 45° angle, hold the caulking gun, apply even pressure, and smoothly apply sealant along the gap. After applying a section, wipe away excess sealant with your finger (or a special scraper), and carefully peel off the tape.

[0059] Comparative Example 1

[0060] A sealant for prefabricated buildings differs from Example 3 in that the alkyl-modified polyaspartic acid ester resin is replaced with an equal mass of organosilicon-modified polyether resin (purchased from Jiangsu Ruiyang Antai New Material Technology Co., Ltd., model 3623T). The content of other raw material components and the preparation method are the same as in Example 3.

[0061] Comparative Example 2

[0062] A sealant for prefabricated buildings differs from Example 3 in that 120 parts by weight of alkyl-modified polyaspartic acid ester resin are replaced with 110 parts by weight of 107 silicone oil and 10 parts by weight of dimethyl silicone oil. The content of other raw material components and the preparation method are the same as in Example 3.

[0063] The sealants for prefabricated buildings prepared in Examples 1-3 and Comparative Examples 1-2 were subjected to performance tests, and the test results are shown in Table 1. All test results in Table 1 are average values ​​from multiple batches of products.

[0064] Table 1

[0065]

[0066] Although the invention has been specifically shown and described in conjunction with preferred embodiments, those skilled in the art should understand that various changes in form and detail may be made to the invention without departing from the spirit and scope of the invention as defined in the appended claims, all of which shall be within the scope of protection of the invention.

Claims

1. A sealant for prefabricated buildings, characterized in that: The raw material components include the following parts by weight: 100-140 parts of alkyl-modified polyaspartic acid ester resin, 20-40 parts of plasticizer, 80-140 parts of reinforcing filler, 2.5-6.5 parts of additives, 2-7 parts of silane coupling agent, and 1-2.5 parts of catalyst; The alkyl-modified polyaspartic acid ester resin is prepared by the following method: (1) Add the amine resin to a high-pressure reactor equipped with a stirrer and a thermometer. Under stirring, slowly add unsaturated dicarboxylic acid esters and unsaturated monocarboxylic acid esters, maintain the temperature at 40-50°C, raise the temperature to 90-100°C after the addition is completed, keep the temperature for 12-15 hours, and then lower the temperature to below 40°C to obtain polyaspartic acid ester resin. The amine resin is any one of 4,4'-diaminodicyclohexylmethane and 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane or a mixture of the two in any ratio. The unsaturated dicarboxylic acid ester is any one of diethyl maleate, dimethyl maleate, and dibutyl maleate or a mixture of two or more in any ratio. The unsaturated monocarboxylic acid ester is any one of alkyl acrylate and alkyl methacrylate or a mixture of the two in any ratio. (2) Evacuate the vacuum and control the vacuum degree at 100-300 Pa. Then turn on the stirrer and introduce nitrogen gas until the pressure inside the reactor is 3-5 kPa. Then slowly add the isocyanate coupling agent and react at 40-50°C for 10-15 h to obtain alkyl-modified polyaspartic acid ester resin. The isocyanate coupling agent is any one of 3-isocyanate-propyltrimethoxysilane and 3-isocyanate-propyltriethoxysilane or a mixture of the two in any ratio. The alkyl-modified polyaspartic acid ester resin has Si-O bonds introduced into its molecular structure, and its main chain structure is N-CO-N. The curing mechanism of the sealant is as follows: the siloxane groups in the alkyl-modified polyaspartic acid ester resin molecules hydrolyze and condense upon contact with air to form a Si-O-Si polymer, thereby curing into a film. The sealant meets the following performance characteristics: tensile modulus ≤ 0.35 MPa at 168h, and color change and chalking grade 0 after 1000h xenon lamp aging.

2. The sealant for prefabricated buildings according to claim 1, characterized in that: The reinforcing filler is any one of nano-calcium carbonate, fumed silica, and carbon black.

3. The sealant for prefabricated buildings according to claim 1, characterized in that: The additives are dehydrating agents and ultraviolet absorbers, comprising 44-50% dehydrating agent and 50-56% ultraviolet absorbers by mass percentage.

4. The sealant for prefabricated buildings according to claim 1, characterized in that: The silane coupling agent is any one of γ-aminopropyltriethoxysilane and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, or a mixture of the two in any ratio.

5. A method for preparing a sealant for prefabricated buildings as described in claim 1, characterized in that: Includes the following steps: S1. Weigh each raw material according to the predetermined weight and set aside; S2. Add alkyl-modified polyaspartic acid ester resin, plasticizer, reinforcing filler, and additives to a planetary reactor. Dehydrate under vacuum at 110-130°C for 1-3 hours, then cool to below 50°C. Add silane coupling agent and catalyst, and stir under vacuum until homogeneous to obtain the required sealant for prefabricated buildings. Discharge the material and store it in a high-density polyethylene plastic tube.

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