Quick-curing matte silicone sealant and preparation method thereof

Abstract

The invention relates to the technical field of silicone rubber sealing materials, and discloses a fast-curing matte silicone sealant and a preparation method thereof.The silicone sealant is prepared from, by mass, 100 parts of alpha, omega-dihydroxy polydimethylsiloxane, 5-15 parts of a reactive plasticizer, 70-120 parts of calcium carbonate, 5-10 parts of a cross-linking agent, 1-5 parts of a coupling agent, 0.5 part of a catalyst and 0.5-1 part of a vulcanization accelerator; 0.2 to 1.5 parts of a reaction type matte agent solution; the reaction type matte agent solution is a mixture of hydroxylated eleostearic acid triglyceride and a cross-linking agent. The silicone sealant prepared by the invention has the advantages of smooth surface, excellent matte effect, weather aging resistance, thixotropy, rapid curing and the like, can be used as a sealing material for high-end buildings, and has a wide application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of silicone sealant, in particular to a fast-curing matte silicone sealant and a preparation method thereof. BACKGROUND

[0002] With the development of social economy and the improvement of consumer aesthetic taste, the construction industry is undergoing a comprehensive upgrade from functionality to quality and artistry. High-end buildings not only pursue the fusion of minimalism and aesthetics in design, but also pay more attention to the expression of texture and details in material selection. In this context, matte products have gradually become an indispensable element in modern high-end construction due to their low-key and restrained visual language, excellent weather resistance, and natural material texture. Especially in the field of building sealant, matte silicone sealant is widely used in key positions such as indoor decoration, door and window systems, and curtain wall joint treatment due to its unique combination of decorative effect and practical function. Compared with traditional bright sealant, matte products can effectively reduce light reflection, creating a softer and more stable space atmosphere, while also having good ultraviolet aging resistance and long-term stability, meeting the dual demands of high-end buildings for aesthetics and durability.

[0003] Currently, there are related technologies that have disclosed a silicone sealant with a matte effect and a preparation method thereof. This scheme mainly uses a first matting powder and / or a second matting powder as the matte component, where the first matting powder is silica particles with a particle size range of 3 μm~30 μm, and the second matting powder includes one or more combinations of silicon powder, mica powder, or talc powder, with a particle size controlled between 10 μm~50 μm. These inorganic fillers achieve a matte surface effect through physical shielding and light scattering. However, due to the high amount of matting powder added (usually between 15 parts and 30 parts), it can easily affect the smoothness and delicate touch of the sealant surface, thereby affecting the overall construction quality and appearance. In addition, some technologies also attempt to achieve a matte effect by introducing natural plant oil components. For example, Chinese patent CN106634802A proposes a preparation method for a fluorescent matte silicone, which adds tung oil as a matte agent to achieve the effect of reducing gloss. However, this method does not modify the tung oil, which has poor compatibility with the silicone system, easily leading to unstable phenomena such as layering and precipitation during storage, thereby affecting the actual application performance.

[0004] In summary, although existing technologies have made some progress in the development of matte sealant, they still face problems such as poor surface texture and poor compatibility of additives. Therefore, there is an urgent need to develop a matte silicone sealant that can ensure matte effect while considering the leveling, stability, and construction performance of the sealant. SUMMARY

[0005] The present application intends to provide a fast-curing matte silicone sealant and a preparation method thereof, so as to solve the problem that the silicone sealant in the prior art is difficult to balance the leveling property, stability and construction performance of the sealant.

[0006] To achieve the above-mentioned purpose, the present application adopts the following technical scheme: a fast-curing matte silicone sealant, by mass fraction, comprising α, ω-dihydroxy polydimethylsiloxane 100 parts, reactive plasticizer 5-15 parts, calcium carbonate 70-120 parts, crosslinking agent 5-10 parts, coupling agent 1-5 parts, catalyst 0.5 parts, vulcanization accelerator 0.5-1 part, and reactive matte agent solution 0.2-1.5 parts; the reactive matte agent solution is a mixture of hydroxylated tung oil acid triglyceride and crosslinking agent. Preferably, as an improvement, the molar ratio of the hydroxylated tung oil acid triglyceride to the crosslinking agent is 1:1.5-3.5, and the crosslinking agent is methyl trimethoxysilane.

[0007] Preferably, as an improvement, the viscosity of the α, ω-dihydroxy polydimethylsiloxane is 40,000-60,000 mPa·s.

[0008] Preferably, as an improvement, the viscosity of the reactive plasticizer is 100-500 mPa·s, and the reactive plasticizer is silicone oil, which has a siloxane chain as a main chain and contains an epoxy or hydroxyl group in a side chain or an end group.

[0009] Preferably, as an improvement, the calcium carbonate is nano active calcium carbonate, which is surface treated by stearic acid, silane coupling agent or titanate coupling agent in combination with polyethylene wax.

[0010] Preferably, as an improvement, the crosslinking agent is at least one of methyl tributanone oxime silane, vinyl tributanone oxime silane, phenyl tributanone oxime silane and tetrabutanone oxime silane; the coupling agent is at least one of r-aminopropyl triethoxysilane, r-aminopropyl triethoxysilane, γ-glycidyl ether propyl trimethoxysilane and dodecyl trimethoxysilane; and the catalyst is at least one of dibutyl tin dilaurate, dibutyl tin dioctanoate, dibutyl tin diacetate and dimethoxy dibutyl tin.

[0011] Preferably, as an improvement, the vulcanization accelerator is at least one of formamide, N,N dimethyl formamide and methyl formamide.

[0012] Preferably, as an improvement, a preparation method of the fast-curing matte silicone sealant comprises the following steps: S1, α, ω-dihydroxy polydimethylsiloxane and nano active calcium carbonate are stirred under vacuum conditions and the reactive plasticizer is added, and then dehydration stirring is continued to obtain a mixture A; S2, hydroxylated tung oil acid triglyceride and methyl trimethoxysilane are mixed in a molar ratio of 1:1.5-3.5, and a reaction type matte agent solution is obtained under nitrogen protection; S3, the reaction type matte agent solution is added to the mixed material A, and mixed under vacuum; then a crosslinking agent and a vulcanization accelerator are added and continuously stirred under vacuum, to obtain mixed material B; S4, a coupling agent and a catalyst are added to the mixed material B, and mixed under vacuum, to obtain the fast-curing matte type silicone sealant.

[0013] Preferably, as an improvement, the hydroxyl value of the hydroxylated tung oil acid triglyceride in step S2 is ≥200 mg KOH / g.

[0014] Preferably, as an improvement, the reaction temperature in step S2 is 50-70°C, and the reaction is stirred for 1-3 h.

[0015] The principle and advantages of the present scheme are: in actual application, the matt glue in the prior art has the problems of too fast attenuation of matt effect, poor mechanical properties of the glue after adding light extinction agent, and slow curing; in view of the problem that the matt silicone sealant in the prior art is difficult to balance the leveling property, stability and construction performance of the sealant, the present scheme comprehensively optimizes the formula composition and preparation process of the matt silicone sealant, aiming to improve the compatibility and stability of the light extinction agent and the sealant: in the formula optimization, α, ω-dihydroxy polydimethylsiloxane is used as the main film-forming material of the sealant, the hydroxyl (-OH) in the molecular chain thereof reacts with the crosslinking agent in the reactive matt agent solution in advance to form a three-dimensional network structure, thereby giving the sealant elasticity and adhesion. The viscosity is controlled to be 40000-60000 mPa·s, the degree of molecular chain entanglement can be adjusted by matching two high and low viscosity 107 glues, the crosslinking density is improved on the basis of ensuring the strength and elongation, and the mechanical properties are ensured. The reactive plasticizer has a siloxane chain as a main chain, and contains an epoxy / hydroxyl group in a side chain or an end group, and has plasticizing and reactivity. The plasticizing effect improves the flowability of the glue by reducing the intermolecular force; the reactive group can participate in the crosslinking reaction to enhance the cohesive force of the sealant, accelerate deep curing, and avoid the problem of traditional plasticizer bleeding. In the selection of fillers, calcium carbonate is used as a raw material, which is surface treated by stearic acid, silane coupling agent or titanate coupling agent and polyethylene wax, so that the surface polarity is reduced, the compatibility with the polymer is enhanced, the thixotropy is improved, the glue does not drip and is easy to extrude during construction, and the construction performance is improved. The nanoscale size can fill the intermolecular space to form physical crosslinking points; the surface treatment agent is combined with the polymer through hydrogen bonds or chemical bonds to improve the interfacial action. In addition, the present scheme performs pre-reaction treatment on the matt solution, the hydroxylated tung oil acid triglyceride contains multiple hydroxyl groups, and reacts with a crosslinking agent (such as methyltrimethoxysilane) at a molar ratio of 1:1.5-3.5 to form micron-sized matt particles. These particles are uniformly dispersed in the glue, the glue surface is atomized, light scattering is achieved, and the matt effect is realized; at the same time, the reactive structure of the plasticizer makes it covalently combined with the polymer network, avoiding the migration of the matt agent, thereby improving the long-term storage stability and avoiding the attenuation of the matt effect. The vulcanization accelerator stabilizes the crosslinking transition state through strong polarity, reduces the activation energy of hydrolysis and condensation reaction through hydrogen bond action, and accelerates curing; at the same time, it promotes the dispersion of the matt agent particles and the light extinction effect, and shortens the light extinction time.

[0016] The present scheme solves the problem that the traditional silicone glue is difficult to balance the leveling property, curing speed and appearance stability by matching the reactive plasticizer and crosslinking agent and pre-reaction of the matt agent; in the preparation process, vacuum dehydration and pre-preparation of the matt agent improve the uniformity and reaction efficiency of the system, realize the double breakthrough of fast curing and matt effect, and make the matt sealant prepared by the present scheme have the functions of sealing, decoration (matt) and environmental adaptability, thereby widening the application scene of the silicone sealant in the high-end building decoration field.

[0017] In summary, the technical scheme has the beneficial effects of: 1. Optimized construction performance: The reaction-type plasticizer and nano active calcium carbonate in the technical scheme synergistically improve the thixotropy of the rubber compound, making the extrusion smooth and non-sagging, suitable for vertical surface or complex interface construction; the catalyst and vulcanization accelerator accelerate the curing, shorten the surface drying time (fast curing property), and reduce the pollution risk and waiting time after construction.

[0018] 2. Ensure the leveling property and appearance effect: The reaction-type plasticizer improves the flowability of the rubber compound, and the surface is smooth and flat after construction, with excellent leveling property; the reaction-type matte agent is uniformly dispersed to form a stable matte surface (controllable gloss), meeting the decorative requirements, and not fading or whitening after long-term use.

[0019] 3. Improve the curing ability: The three-functional and four-functional crosslinking agents in the technical scheme are combined with high-viscosity base polymers to increase the crosslinking density and accelerate the synchronous curing of the surface layer and the deep layer; the vulcanization accelerator reduces the reaction activation energy through hydrogen bonding, especially improving the deep layer curing speed, avoiding the problem of "surface drying and deep layer not drying", and being suitable for thick coating scenarios.

[0020] 4. Ensure the storage stability and environmental adaptability of the sealant: The reaction-type matte agent pretreatment process in the technical scheme covalently combines with the polymer network, avoiding the precipitation or agglomeration of the matte agent during storage; the surface-modified nano calcium carbonate has good compatibility with the polymer, and the system has no sedimentation or stratification, prolonging the storage period; the siloxane crosslinking network gives the sealant excellent weather resistance (anti-ultraviolet, high and low temperature resistance), suitable for outdoor building curtain wall scenarios.

[0021] 5. Consider the mechanical properties: The high crosslinking density in the technical scheme ensures the tensile strength, elongation at break, and elastic recovery rate of the sealant, which can adapt to the thermal expansion and contraction and displacement changes of the substrate; the nano calcium carbonate enhances the hardness and compression deformation resistance, improving the service life of the sealant. DETAILED DESCRIPTION

[0022] The embodiments of the present application will be further described in detail below, but the embodiments of the present application are not limited thereto. If not specifically indicated, the technical means used in the following embodiments are conventional means known to those skilled in the art; the experimental methods used are conventional methods; the materials, reagents, etc. used can be obtained from commercial channels.

[0023] General description of the scheme: A fast-curing matte silicone sealant, comprising, by mass fraction, alpha, omega-dihydroxypolydimethylsiloxane 100 parts, reactive plasticizer 5-15 parts, nano active calcium carbonate 70-120 parts, crosslinking agent 5-10 parts, coupling agent 1-5 parts, catalyst 0.5 parts, vulcanization accelerator 0.5-1 part, and reactive matte agent solution 0.2-1.5 parts; the reactive matte agent solution is a mixture of hydroxylated tung oil acid triglyceride and crosslinking agent; the hydroxyl value of the hydroxylated tung oil acid triglyceride is greater than or equal to 200 mg KOH / g; the preparation method of the reactive matte agent solution is as follows: hydroxylated tung oil acid triglyceride and methyltrimethoxysilane are mixed in a molar ratio of 1:1.5-3.5, heated to 50-70 DEG C under nitrogen protection, and stirred for 1-3 hours (the end point is determined by monitoring the amount of methanol released), and then cooled to room temperature to obtain.

[0024] The alpha, omega-dihydroxypolydimethylsiloxane is obtained by mixing two high and low viscosity 107 glues with a viscosity of 40,000-600,000 mPa.s.

[0025] The viscosity of the reactive plasticizer is 100-500 mPa.s; the reactive plasticizer is silicone oil, the silicone oil has a siloxane chain as a main chain, and side chains or end groups contain epoxy or hydroxyl groups; the silicone oil has certain reactivity advantages, and is used in the use of building curtain walls and marble curtain walls to prevent seepage and pollution of the base material.

[0026] The nano active calcium carbonate is surface treated by stearic acid, silane coupling agent or titanate coupling agent in combination with polyethylene wax to improve the thixotropy and construction performance of the product.

[0027] The crosslinking agent is at least one of methyltris(butanone oxime) silane, vinyltris(butanone oxime) silane, phenyltris(butanone oxime) silane and tetrabutanone oxime silane, which is used in combination with a trifunctional crosslinking agent to improve the curing speed of the product.

[0028] The coupling agent is at least one of r-aminopropyl triethoxysilane, r-aminopropyl triethoxysilane, gamma-glycidoxypropyl trimethoxysilane and dodecyl trimethoxysilane.

[0029] The catalyst is at least one of dibutyltin dilaurate, dibutyltin dioctoate, dibutyltin diacetate and dimethoxydibutyltin.

[0030] The vulcanization accelerator is at least one of formamide, N,N dimethylformamide and methylformamide, which has strong polarity to stabilize the crosslinking transition state, reduce the activation energy of hydrolysis and condensation reaction through hydrogen bonding, accelerate condensation, improve deep curing, and speed up the extinction of the matte sealant.

[0031] A preparation method of a fast-curing matte type silicone sealant, comprising the following steps: S1, α, ω-dihydroxy polydimethylsiloxane (107 glue), nano active calcium carbonate, after stirring uniformly, vacuum stirring under a vacuum degree of -0.08 to -0.095 MPa; adding a reactive plasticizer, vacuum dehydration stirring under a vacuum degree of -0.095 to -0.08 MPa for 2 h, to obtain a mixture A; S2, hydroxylated tung oil acid triglyceride (hydroxyl value ≥200 mg KOH / g) is mixed with methyltrimethoxysilane at a molar ratio of 1:1.5-3.5, under nitrogen protection, heated to 50-70℃, and stirred for 1-3 h (the end point is judged by monitoring the amount of methanol released), and then cooled to room temperature to obtain a reactive matte agent solution; S3, adding the reactive matte agent solution to the mixture A, and mixing under vacuum at a vacuum degree of -0.08 to -0.095 MPa for 10 min; then adding a crosslinking agent and a vulcanization accelerator, and mixing under vacuum at a vacuum degree of -0.08 to -0.095 MPa for 30 min, to obtain a mixture B; S4, adding a coupling agent and a catalyst to the mixture B, and mixing under vacuum at a vacuum degree of -0.08 to -0.095 MPa for 30 min to disperse uniformly, to obtain the product.

[0032] Examples 1-5 are embodiments of the present application, and Comparative Examples 1-5 are comparative examples of the present application. The types and amounts of raw materials of each example and comparative example are shown in Table 1. The preparation process of the silicone sealant of each example and comparative example is as described above. In Table 1, α, ω-dihydroxy polydimethylsiloxane (20,000 107) refers to α, ω-dihydroxy polydimethylsiloxane with a viscosity of 20,000 mPa·s.

[0033] Table 1

[0034] The silicone sealants prepared in each example and comparative example are tested for performance, and the test indexes and test methods are as follows: Tensile bonding strength, MPa: the test method refers to GB / T 16776-2005; Maximum strength elongation, %: the test method refers to GB / T 16776-2005; Bonding failure area, %: the test method refers to GB / T 16776-2005; Tensile modulus at 23℃, MPa: the test method refers to GB / T 14683-2017; 100% extension bonding: the test method refers to GB / T 14683-2017; 24h surface gloss / 60° specular gloss: the test method refers to GB / T 4893.6-2013 to test the gloss of the surface (the test angle is 60°, and the test results are used as the value); Curing speed, mm: the test method refers to QC / T 1024-2015; Each group was tested in triplicate, and the test results are shown in Table 2. As can be seen from the data in Table 2, by Examples 1-5, it can be seen that the specular gloss is significantly reduced by adding 0.2 and more parts of the matting agent, and the use of the matting agent has no effect on the curing speed of the product. And Examples 1-5 can take into account the mechanical properties and long-term storage stability of the sealant by incorporating the reactive matte solution, crosslinking agent and reactive plasticizer.

[0035] As can be seen from the comparative examples, using a single 20,000 viscosity 107 glue to prepare the product has a good curing speed, but has a certain effect on the elongation rate of the product. Using a single 80,000 viscosity 107 glue to prepare the product significantly improves the elongation rate but has a low crosslinking density and a slow curing speed, which has some effect on the adhesion. The use of 20,000 and 80,000 viscosity together has the best effect. Comparative Example 4 can obviously see that the use of tetrabutyl ketoxime silane crosslinking activity improves the curing speed of the product, and Comparative Example 5 uses a promoter to accelerate the condensation reaction to further improve the deep curing speed of the product. Compared with Example 5, the use of a promoter significantly affects the 24h specular gloss effect and the deep curing speed of the product. Comparative Example 6 uses cyclohexene as a matting agent, although it can obtain a matte product, but the test results show that the mechanical properties are significantly reduced, and the adhesion and curing speed are significantly reduced.

[0036] Table 2

[0037] The above is only an embodiment of the present application, and the specific technical solutions and / or common knowledge of the scheme are not described in detail. It should be noted that for those skilled in the art, without departing from the technical solutions of the present application, a number of modifications and improvements can be made, which should be considered as the protection scope of the present application, which will not affect the effect and practicality of the patent. The protection scope claimed in this application should be subject to the content of its claims, and the specific embodiments described in the specification can be used to explain the content of the claims.

Claims

1. A fast-curing matte silicone sealant, characterized by: The silicone sealant comprises, in parts by mass, 100 parts of alpha, omega-dihydroxypolydimethylsiloxane, 5-15 parts of reactive plasticizer, 70-120 parts of calcium carbonate, 5-10 parts of crosslinking agent, 1-5 parts of coupling agent, 0.5 part of catalyst, 0.5-1 part of vulcanization accelerator, and 0.2-1.5 parts of reactive matte agent solution; the reactive matte agent solution is a mixture of hydroxylated tung oil acid triglyceride and crosslinking agent.

2. The fast-curing matte silicone sealant according to claim 1, characterized in that: The molar ratio of the hydroxylated tung oil acid triglyceride to the crosslinking agent is 1:1.5-3.5, and the crosslinking agent is methyltrimethoxysilane.

3. The fast-curing matte silicone sealant according to claim 2, characterized in that: The viscosity of the alpha, omega-dihydroxypolydimethylsiloxane is 40,000-60,000 mPa·s.

4. The fast-curing matte silicone sealant according to claim 3, characterized in that: The viscosity of the reactive plasticizer is 100-500 mPa·s, and the reactive plasticizer is silicone oil, which has a siloxane chain as a main chain and contains an epoxy or hydroxyl group in a side chain or end group.

5. The fast-curing matte silicone sealant according to claim 4, characterized in that: The calcium carbonate is nano active calcium carbonate, which is surface treated by stearic acid, silane coupling agent or titanate coupling agent in combination with polyethylene wax.

6. The fast-curing matte silicone sealant according to claim 5, characterized in that: The crosslinking agent is at least one of methyltributanoxysilane, vinyltributanoxysilane, phenyltributanoxysilane and tetrabutanoxysilane; the coupling agent is at least one of r-aminopropyltriethoxysilane, r-aminopropyltriethoxysilane, gamma-glycidoxypropyltrimethoxysilane and dodecyltrimethoxysilane; and the catalyst is at least one of dibutyltin dilaurate, dibutyltin dioctoate, dibutyltin diacetate and dimethoxydibutyltin.

7. The fast-curing matte silicone sealant according to claim 6, characterized in that: The vulcanization accelerator is at least one of formamide, N,N dimethylformamide and methylformamide.

8. The preparation method of the fast-curing matte silicone sealant according to any one of claims 1-7, characterized in that, The silicone sealant comprises the following steps: S1, stirring alpha, omega-dihydroxypolydimethylsiloxane and nano active calcium carbonate under vacuum conditions, and adding reactive plasticizer, and continuing to stir and dehydrate to obtain mixture A; S2, mixing hydroxylated tung oil acid triglyceride and methyltrimethoxysilane at a molar ratio of 1:1.5-3.5, and reacting under nitrogen protection to obtain a reactive matte agent solution; S3, adding the reactive matte agent solution to mixture A, and mixing under vacuum conditions; then adding crosslinking agent and vulcanization accelerator, and continuing to stir under vacuum to obtain mixture B; S4, adding coupling agent and catalyst to mixture B, and mixing under vacuum to obtain the silicone sealant.

9. A method for preparing a fast-curing matte silicone sealant according to claim 8, characterized in that: In step S2, the hydroxyl value of the hydroxylated tung oil acid triglyceride is greater than or equal to 200 mg KOH / g.

10. A method for preparing a fast-curing matte silicone sealant according to claim 9, characterized in that: In step S2, the reaction is carried out at a temperature of 50-70 ℃ for 1-3 h.

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