A silicone sealant containing natural fiber and its preparation method and application

Abstract

The invention relates to the technical field of silicone adhesives, in particular to a silicone sealant containing natural fibers, and a preparation method and application thereof. The silicone sealant containing natural fibers comprises 80-90 parts of alkoxy-terminated polydimethylsiloxane, 30-50 parts of plasticizer, 15-35 parts of filler, 3-8 parts of crosslinking agent, 1.5-3.5 parts of curing accelerator, 0.5-1 part of catalyst, 0.5-1 part of coupling agent, 0.5-2 parts of stabilizer, 4-5.5 parts of natural fibers, 3-6 parts of dispersant and 1-2 parts of reversible swelling material, wherein the natural fibers are used to form an irregular three-dimensional network in the silicone sealant to reduce the occurrence of debonding; the curing accelerator constructs micropores, and the reversible swelling material makes it difficult for rainwater to enter indoors through the micropores or gaps; and the preparation method of the silicone sealant containing natural fibers comprises the steps of soaking the natural fibers in the dispersant to obtain a mixture, and respectively adding the mixture while adding the plasticizer, the crosslinking agent, the filler and the reversible swelling material to reduce the aggregation of the natural fibers.

Description

Technical Field

[0001] The invention relates to the technical field of silicone sealants, in particular to a silicone sealant containing natural fibers and a preparation method and application thereof. Background Art

[0002] In addition to the hard connection between the window frames and building walls of modern high-rise buildings, silicone glue (also called glass glue) is also needed to fill and bond the gap between the window frames and the walls. Silicone glue is divided into acidic silicone glue and neutral silicone glue. Because acidic silicone glue can quickly form initial adhesion and has better sealing properties, especially in environments with high humidity, it is suitable for window frames, but it should be pointed out that acidic silicone glue contains acetic acid, which is corrosive to metal window frames. Neutral silicone glue does not contain acidic substances and will not corrode metal window frames, but the sealing properties of neutral silicone glue are slightly worse. After the existing neutral silicone glue is cured, it is easy to debond due to cold shrinkage in the case of rapid cooling (that is, the adhesive surface of the silicone glue is separated from the adhered object), and cooling often brings precipitation, so water seepage may occur at the edge of the window frame. Summary of the invention

[0003] In view of the shortcomings of the prior art, one of the purposes of the present invention is to provide a silicone sealant containing natural fibers, which utilizes natural fibers to construct a skeleton in the cured colloid, thereby reducing the extent of shrinkage when exposed to cold, thereby avoiding debonding and water seepage; its ingredients do not contain acetic acid or other acids, and are not easy to corrode metal window frames.

[0004] A second object of the present invention is to provide a method for preparing a silicone sealant containing natural fibers.

[0005] One of the purposes of the present invention is achieved through the following technical solutions:

[0006] A silicone sealant containing natural fibers is prepared from the following raw materials in parts by weight:

[0007] 80-90 parts of alkoxy-terminated polydimethylsiloxane, 30-50 parts of plasticizer, 15-35 parts of filler, 3-8 parts of cross-linking agent, 1.5-3.5 parts of curing accelerator, 0.5-1 part of catalyst, 0.5-1 part of coupling agent, 0.5-2 parts of stabilizer, 4-5.5 parts of natural fiber, 3-6 parts of dispersant and 1-2 parts of reversible swelling material, the curing accelerator is ethyl acetate, and magnetic coating layers are formed at both ends of the natural fiber.

[0008] Preferably, the plasticizer is dimethyl silicone oil, the filler is fumed silica, the crosslinker is tetramethoxysilane, the catalyst is acetylacetone chelate of dibutyltin dilaurate, the coupling agent is silane coupling agent KH-792, and the stabilizer is hexamethylcyclotrisilazane.

[0009] Preferably, the natural fiber is flax fiber.

[0010] Preferably, the dispersant is epoxidized soybean oil.

[0011] Preferably, the reversible swelling material is wormwood glue powder. wormwood glue is insoluble in water and has swelling properties, and wormwood glue is acid and alkali resistant.

[0012] The second object of the present invention is achieved by the following technical solutions:

[0013] A method for preparing a silicone sealant containing natural fibers comprises the following steps:

[0014] S1 weighs the raw materials;

[0015] S2: soaking the natural fiber in a dispersant to obtain a mixture, and dividing the mixture into 4 parts by equal weight; the natural fiber in the present invention has a magnetic coating layer at both ends, so the natural fiber is easy to aggregate, and the weight of the fiber monomer is increased and the surface friction is reduced by adsorbing the dispersant on the natural fiber, and then adding a small amount of it to the stirring material multiple times to effectively reduce the aggregation; in addition, the fiber strength, elasticity and toughness of the natural fiber after being soaked in the dispersant are significantly improved.

[0016] S3: stirring alkoxy-terminated polydimethylsiloxane in a nitrogen-based atmosphere, and adding plasticizer, cross-linking agent, filler and reversible swelling material to the alkoxy-terminated polydimethylsiloxane at intervals during the stirring process, and adding one portion of the mixture to each of the plasticizer, cross-linking agent, filler and reversible swelling material; mixing, and then vacuuming off low-boiling substances to obtain a colloid; when natural fibers are added, they are added together with other raw materials to reduce the number of feeding times and reduce the loss of the dispersant during the feeding process by temporarily attaching other raw materials to the natural fibers adsorbed with the dispersant;

[0017] S4 stirs the colloid, and adds the catalyst, coupling agent, stabilizer and curing accelerator at intervals during the stirring process; mixes the colloid, and then removes the low-boiling substances in vacuum to obtain the silicone sealant.

[0018] Preferably, in step S1, the raw materials are heated to 60-70° C. and kept warm for later use. Keeping the raw materials warm can reduce the temperature difference between various raw materials in subsequent steps, which is beneficial to the reaction.

[0019] Preferably, the step S3 uses a temperature-controlled reactor (that is, a reactor with a heat exchange jacket, and the temperature in the reactor can be adjusted as needed) for stirring and mixing. In the step S3, the material temperature is controlled at 70-80°C, the feeding interval is 5-10min, the mixing time is 50-70min, the stirring and mixing speed is 250-350r / min, and the vacuum degree is -0.1MPa.

[0020] Preferably, the step S4 uses a reactor for stirring and mixing, the feeding interval in the step S4 is 30-60s, the mixing time is 10-20min, the stirring and mixing speed is 300-400r / min, and the vacuum degree is -0.09MPa.

[0021] The third object of the present invention is achieved by the following technical solutions:

[0022] A silicone sealant containing natural fibers, used to fill the gap between the wall and the metal window frame.

[0023] The beneficial effects of the present invention are as follows: an irregular three-dimensional network is formed in the silicone sealant by utilizing natural fibers, thereby constructing an internal skeleton. Under the restraint of this skeleton, the silicone sealant shrinks when exposed to cold or expands when exposed to water, and the deformation range of its appearance is limited and its own mechanical strength is improved, thereby reducing the occurrence of debonding; a large number of micropores are constructed on the silicone sealant through the rapid volatilization of the curing accelerator, which is conducive to water absorption and evaporation. When rainwater enters from the micropores, the silicone sealant is expanded by the swelling effect of the reversible swelling material widely present in the silicone sealant, thereby blocking the gap between the silicone sealant and the wall or window frame. The reversible swelling material also blocks the micropores by the swelling effect, thereby making it difficult for rainwater to enter the room through the micropores or gaps. When the rainy day is over, the water can evaporate and escape from the reversible swelling material and the silicone sealant along the micropores, and the reversible swelling material and the silicone sealant are restored. In addition, the reversible swelling material and flax fiber used in the present invention are both acid-resistant and alkali-resistant, so they can also resist the erosion of the internal structure of the silicone sealant by acid rain or wall alkali return, thereby extending the service life of the silicone sealant. DETAILED DESCRIPTION

[0024] The specific embodiments of the present invention are further described below in conjunction with comparative examples:

[0025] Example 1

[0026] A method for preparing a silicone sealant containing natural fibers comprises the following steps:

[0027] S1 was weighed in parts by weight: 81 parts of alkoxy-terminated polydimethylsiloxane, 32 parts of plasticizer, 17 parts of filler, 4 parts of cross-linking agent, 1.7 parts of curing accelerator, 0.6 parts of catalyst, 0.6 parts of coupling agent, 0.8 parts of stabilizer, 4.7 parts of natural fiber, 3.5 parts of dispersant and 1.1 parts of reversible swelling material.

[0028] Wherein: the plasticizer is dimethyl silicone oil, the filler is fumed silica, the cross-linking agent is tetramethoxysilane, the curing accelerator is ethyl acetate, the catalyst is acetylacetone chelate of dibutyltin dilaurate, the coupling agent is silane coupling agent KH-792, the stabilizer is hexamethylcyclotrisilazane, the natural fiber is flax fiber and magnetic coating layers are formed at both ends of the natural fiber, the dispersant is epoxy soybean oil, and the reversible swelling material is artemisia gum powder.

[0029] The raw materials are heated to 61° C. and kept warm for later use.

[0030] S2: soaking the natural fiber in the dispersant to obtain a mixture, and dividing the mixture into 4 equal parts by weight; here, the mixture can be divided into equal parts without distinguishing the specific content of the natural fiber or the dispersant in each part in detail.

[0031] S3 uses a temperature-controlled reactor to stir alkoxy-terminated polydimethylsiloxane in a nitrogen-based atmosphere, and the material temperature is controlled at 70-75°C. During the stirring process, plasticizers, cross-linking agents, fillers and reversible swelling materials are added to the alkoxy-terminated polydimethylsiloxane at intervals. When adding plasticizers, cross-linking agents, fillers and reversible swelling materials, one portion of the mixture is added respectively, and the feeding interval time is 6 minutes; mixing, the mixing time is 52 minutes, the stirring and mixing speed is 270r / min, and then low-boiling substances are removed by vacuum, the vacuum degree is -0.1MPa, and a colloid is obtained; stirring and mixing are performed.

[0032] S4 uses a reaction kettle to stir the colloid, and adds catalyst, coupling agent, stabilizer and curing accelerator at intervals during the stirring process, with a feeding interval of 32s; mixing, the mixing time is 11min, the stirring and mixing speed is 310r / min, and then the low-boiling substances are removed by vacuum, the vacuum degree is -0.09MPa, and the silicone sealant is obtained.

[0033] The method for forming the magnetic coating layer at both ends of the natural fiber described in this article is:

[0034] The flax fibers with a length of 1-5 mm were selected, and both ends were immersed in the nano-ferromagnetic solution for 30 minutes, and then taken out and dried at 80°C, and this process was repeated three times.

[0035] Example 2

[0036] A method for preparing a silicone sealant containing natural fibers comprises the following steps:

[0037] S1 was weighed in parts by weight: 89 parts of alkoxy-terminated polydimethylsiloxane, 48 parts of plasticizer, 33 parts of filler, 7 parts of cross-linking agent, 3.2 parts of curing accelerator, 0.9 parts of catalyst, 0.9 parts of coupling agent, 1.8 parts of stabilizer, 5.2 parts of natural fiber, 5.8 parts of dispersant and 1.8 parts of reversible swelling material.

[0038] Wherein: the plasticizer is dimethyl silicone oil, the filler is fumed silica, the cross-linking agent is tetramethoxysilane, the curing accelerator is ethyl acetate, the catalyst is acetylacetone chelate of dibutyltin dilaurate, the coupling agent is silane coupling agent KH-792, the stabilizer is hexamethylcyclotrisilazane, the natural fiber is flax fiber and magnetic coating layers are formed at both ends of the natural fiber, the dispersant is epoxy soybean oil, and the reversible swelling material is artemisia gum powder.

[0039] The raw materials are heated to 69° C. and kept warm for later use.

[0040] S2: soaking the natural fiber in a dispersant to obtain a mixture, and dividing the mixture into 4 equal parts.

[0041] S3 uses a temperature-controlled reactor to stir alkoxy-terminated polydimethylsiloxane in a nitrogen-based atmosphere, and the material temperature is controlled at 75-80°C. During the stirring process, plasticizers, cross-linking agents, fillers and reversible swelling materials are added to the alkoxy-terminated polydimethylsiloxane at intervals. When adding plasticizers, cross-linking agents, fillers and reversible swelling materials, one portion of the mixture is added respectively, and the feeding interval time is 9 minutes; mixing, the mixing time is 68 minutes, the stirring and mixing speed is 320r / min, and then low-boiling substances are removed by vacuum, the vacuum degree is -0.1MPa, and a colloid is obtained; stirring and mixing are performed.

[0042] S4 uses a reaction kettle to stir the colloid, and adds catalyst, coupling agent, stabilizer and curing accelerator at intervals during the stirring process, with a feeding interval of 58s; mixing, the mixing time is 19min, the stirring and mixing speed is 390r / min, and then the low-boiling substances are removed by vacuum, the vacuum degree is -0.09MPa, and the silicone sealant is obtained.

[0043] Example 3

[0044] A method for preparing a silicone sealant containing natural fibers comprises the following steps:

[0045] S1 was weighed in parts by weight: 84 parts of alkoxy-terminated polydimethylsiloxane, 39 parts of plasticizer, 24 parts of filler, 5 parts of cross-linking agent, 2.4 parts of curing accelerator, 0.7 parts of catalyst, 0.7 parts of coupling agent, 1.2 parts of stabilizer, 4.9 parts of natural fiber, 4 parts of dispersant and 1.5 parts of reversible swelling material.

[0046] Wherein: the plasticizer is dimethyl silicone oil, the filler is fumed silica, the cross-linking agent is tetramethoxysilane, the curing accelerator is ethyl acetate, the catalyst is acetylacetone chelate of dibutyltin dilaurate, the coupling agent is silane coupling agent KH-792, the stabilizer is hexamethylcyclotrisilazane, the natural fiber is flax fiber and magnetic coating layers are formed at both ends of the natural fiber, the dispersant is epoxy soybean oil, and the reversible swelling material is artemisia gum powder.

[0047] The raw materials are heated to 65° C. and kept warm for later use.

[0048] S2: soaking the natural fiber in a dispersant to obtain a mixture, and dividing the mixture into 4 equal parts.

[0049] S3 uses a temperature-controlled reactor to stir alkoxy-terminated polydimethylsiloxane in a nitrogen-based atmosphere, and the material temperature is controlled at 73-76°C. During the stirring process, plasticizers, cross-linking agents, fillers and reversible swelling materials are added to the alkoxy-terminated polydimethylsiloxane at intervals. When adding plasticizers, cross-linking agents, fillers and reversible swelling materials, one portion of the mixture is added respectively, and the feeding interval time is 7 minutes; mixing, the mixing time is 59 minutes, the stirring and mixing speed is 290r / min, and then low-boiling substances are removed by vacuum, the vacuum degree is -0.1MPa, and a colloid is obtained; stirring and mixing are performed.

[0050] S4 uses a reaction kettle to stir the colloid, and adds catalyst, coupling agent, stabilizer and curing accelerator at intervals during the stirring process, with a feeding interval of 40s; mixing, the mixing time is 14min, the stirring and mixing speed is 340r / min, and then the low-boiling substances are removed by vacuum, the vacuum degree is -0.09MPa, and the silicone sealant is obtained.

[0051] Example 4

[0052] A method for preparing a silicone sealant containing natural fibers comprises the following steps:

[0053] S1 was weighed in parts by weight: 86 parts of alkoxy-terminated polydimethylsiloxane, 41 parts of plasticizer, 26 parts of filler, 6 parts of cross-linking agent, 2.6 parts of curing accelerator, 0.7 parts of catalyst, 0.7 parts of coupling agent, 1.6 parts of stabilizer, 5 parts of natural fiber, 4 parts of dispersant and 1.5 parts of reversible swelling material.

[0054] Wherein: the plasticizer is dimethyl silicone oil, the filler is fumed silica, the cross-linking agent is tetramethoxysilane, the curing accelerator is ethyl acetate, the catalyst is acetylacetone chelate of dibutyltin dilaurate, the coupling agent is silane coupling agent KH-792, the stabilizer is hexamethylcyclotrisilazane, the natural fiber is flax fiber and magnetic coating layers are formed at both ends of the natural fiber, the dispersant is epoxy soybean oil, and the reversible swelling material is artemisia gum powder.

[0055] The raw materials are heated to 65° C. and kept warm for later use.

[0056] S2: soaking the natural fiber in a dispersant to obtain a mixture, and dividing the mixture into 4 equal parts.

[0057] S3 uses a temperature-controlled reactor to stir alkoxy-terminated polydimethylsiloxane in a nitrogen-based atmosphere, and the material temperature is controlled at 74-77°C. During the stirring process, plasticizers, cross-linking agents, fillers and reversible swelling materials are added to the alkoxy-terminated polydimethylsiloxane at intervals. When adding plasticizers, cross-linking agents, fillers and reversible swelling materials, one portion of the mixture is added respectively, and the feeding interval time is 7 minutes; mixing, the mixing time is 61 minutes, the stirring and mixing speed is 310r / min, and then low-boiling substances are removed by vacuum, the vacuum degree is -0.1MPa, and a colloid is obtained; stirring and mixing are performed.

[0058] S4 uses a reaction kettle to stir the colloid, and adds catalyst, coupling agent, stabilizer and curing accelerator at intervals during the stirring process, with an interval of 50s; mixing, the mixing time is 16min, the stirring and mixing speed is 360r / min, and then the low-boiling substances are removed by vacuum, the vacuum degree is -0.09MPa, and the silicone sealant is obtained.

[0059] Comparative Example 1

[0060] The natural fiber raw materials and corresponding steps are eliminated, and other raw materials and steps are the same as those in Example 4.

[0061] Comparative Example 2

[0062] The natural fiber was replaced with cotton fiber, and the other raw materials and steps were the same as those in Example 4.

[0063] Comparative Example 3

[0064] The reversible swelling material and the corresponding steps are eliminated, and the other raw materials and steps are the same as those in Example 4.

[0065] Comparative Example 4

[0066] The reversible swelling material was replaced with a water-absorbing resin, and the other raw materials and steps were the same as those in Example 4.

[0067] Comparative Example 5

[0068] Purchase neutral silicone sealant (Dow Corning 995 silicone sealant) on the market.

[0069] Weathering simulation test

[0070] 1) Experimental purpose: to verify that the silicone sealant obtained by the present invention can maintain dimensional stability in the weather changes of cooling, rain and sunny days.

[0071] 2) Experimental method: the silicone sealants obtained in Examples 1-4 and Comparative Examples 1-3 were placed for 7 days and then made into blocks with a length, width and height of 5 cm (99 blocks of each type), and then subjected to the three steps of freezing, soaking in water and air drying. The height of the corresponding blocks of each silicone sealant was measured after each step, and the average was calculated and recorded. Freezing means placing at -2°C for 8 hours, soaking in water means soaking in clean water at 2°C for 8 hours, and air drying means blowing at 6 m / s at 25°C and 60% relative humidity for 8 hours.

[0072] 3) Experimental results, see Table 1.

[0073] Table 1 Record of average block heights corresponding to each silicone sealant

[0074]

[0075] It can be seen from Table 1 that the silicone sealant obtained by the present invention has good dimensional stability after being frozen, soaked in water and air-dried, while Comparative Example 1 lacks the skeleton restriction of natural fibers, resulting in a large shrinkage when cold and a large expansion when soaked in water; Comparative Example 2 uses cotton fibers as a skeleton, which produces similar effects to the present invention, but it is well known that cotton fibers are not acid-resistant. If the rainwater is acid rain, its service life will be greatly reduced; although Comparative Example 3 has a skeleton restriction and does not shrink much when cold, it lacks expansion components and is not easy to recover.

[0076] Water plugging performance simulation experiment

[0077] 1) Experimental purpose: to verify that the silicone sealant obtained by the present invention has good water blocking function after construction.

[0078] 2) Experimental method: Examples 1-4 and Comparative Examples 1-5 were respectively filled in the gaps between 9 standard single-sash window frames (size 60cm*90cm) and the experimental wall. After standing for 7 days and observing with the naked eye that there were no gaps, the experimental wall was sent to a cold storage at -2°C for 8 hours. Then, the experimental wall was taken out and sprayed with water on one side for 2 hours (tap water). Then, the other side of the experimental wall was observed with the naked eye for water seepage. Then, a hot air blower was used to dry the experimental wall until there were no obvious water marks on both sides of the experimental wall. The silicone sealants were observed with the naked eye for bulging or gaps.

[0079] 3) Experimental results, see Table 2.

[0080] Table 2 Experimental wall water seepage record

[0081]

[0082] As can be seen from Table 2, the silicone sealant obtained by the present invention can still resist the penetration of rainwater even after freezing and shrinkage after construction, and will not have bulges or gaps after drying, and is an excellent antifreeze and water-blocking silicone sealant.

[0083] The above embodiments and descriptions are only for illustrating the principles and best embodiments of the present invention. Without departing from the spirit and scope of the present invention, the present invention may be subject to various changes and improvements, all of which fall within the scope of the present invention to be protected.

Claims

1. An application of a silicone sealant containing natural fibers, characterized in that: The silicone sealant containing natural fibers is used to fill the gap between the wall and the metal window frame; The silicone sealant containing natural fibers is prepared from the following raw materials in parts by weight: 80-90 parts of alkoxy-terminated polydimethylsiloxane, 30-50 parts of plasticizer, 15-35 parts of filler, 3-8 parts of cross-linking agent, 1.5-3.5 parts of curing accelerator, 0.5-1 parts of catalyst, 0.5-1 parts of coupling agent, 0.5-2 parts of stabilizer, 4-5.5 parts of natural fiber, 3-6 parts of dispersant and 1-2 parts of reversible swelling material, wherein the curing accelerator is ethyl acetate, and magnetic coating layers are formed at both ends of the natural fiber; the plasticizer is dimethyl silicone oil, the filler is fumed silica, the cross-linking agent is tetramethoxysilane, the catalyst is acetylacetone chelate of dibutyltin dilaurate, the coupling agent is silane coupling agent KH-792, and the stabilizer is hexamethylcyclotrisilazane; the natural fiber is flax fiber; the dispersant is epoxy soybean oil; and the reversible swelling material is artemisia gum powder; The preparation method comprises the following steps: S1 weighs the raw materials; S2: soaking the natural fiber in a dispersant to obtain a mixture, and dividing the mixture into four equal parts; S3: stirring the alkoxy-terminated polydimethylsiloxane in a nitrogen-based atmosphere, and adding a plasticizer, a cross-linking agent, a filler and a reversible swelling material to the alkoxy-terminated polydimethylsiloxane at intervals during the stirring process, and adding one portion of the mixture to each of the plasticizer, the cross-linking agent, the filler and the reversible swelling material; mixing, and then removing low-boiling substances in vacuum to obtain a colloid; S4: stirring the colloid, adding a catalyst, a coupling agent, a stabilizer and a curing accelerator at intervals during the stirring process; mixing, and then removing low-boiling substances by vacuum to obtain a silicone sealant; In step S1, the raw materials are heated to 60-70° C. and kept warm for later use; The step S3 uses a temperature-controlled reactor for stirring and mixing. In the step S3, the material temperature is controlled at 70-80°C, the feeding interval is 5-10min, the mixing time is 50-70min, the stirring and mixing speed is 250-350r / min, and the vacuum degree is -0.1MPa; The step S4 uses a reaction kettle for stirring and mixing. In the step S4, the feeding interval time is 30-60s, the mixing time is 10-20min, the stirring and mixing speed is 300-400r / min, and the vacuum degree is -0.09MPa.

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