Water plugging silicone glue and preparation method thereof

Abstract

The present application relates to the technical field of silicone glue, and particularly relates to a water plugging silicone glue and a preparation method thereof; the water plugging silicone glue comprises the following components: 80-90 parts of alkoxyl-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 and 5-8 parts of swelling fiber; wherein the swelling fiber is cross-linked PVA fiber; the cross-linked PVA fiber is used to replace natural fiber, so that the acid and alkali resistance is further improved, and the swelling capacity is also provided; the water plugging effect can be achieved without adding sandart glue and other swelling raw materials; the thickness and length of the cross-linked PVA fiber can be accurately controlled, so that the consistency of the silicone glue product quality is improved.

Description

Technical Field

[0001] This invention relates to the field of silicone sealant technology, and in particular to a water-blocking silicone sealant and its preparation method. Background Technology

[0002] In recent years, to address climate change, the industry has developed silicone sealants for waterproofing that possess properties such as acid and alkali resistance and freeze resistance. For example, Chinese patent 117801772 B discloses a silicone sealant containing natural fibers, its preparation method, and its application. The patent describes how natural fibers form an irregular three-dimensional network within the silicone sealant, creating an internal framework. Under the constraint of this framework, the silicone sealant shrinks when cold or expands when wet, limiting its deformation and increasing its mechanical strength, thus reducing the occurrence of delamination. The reversible swelling material and flax fiber used also possess acid and alkali resistance, thus resisting the erosion of the internal structure of the silicone sealant by acid rain or efflorescence on the wall, extending the service life of the silicone sealant.

[0003] The basic principle of the above technical solution is: a three-dimensional network is formed in the silicone sealant by flax fibers, and then the water is blocked by the expansion of the sage sealant. The three-dimensional network can prevent the sage sealant from expanding excessively and prevent the silicone sealant from shrinking excessively at low temperatures.

[0004] The above technical solution has the following defects: 1) The β-1,4 glycosidic bonds of cellulose in flax fiber will break in an acidic environment, while cellulose will swell in an alkaline environment. Therefore, the "acid and alkali resistance" claimed by this technical solution refers to short-term acid and alkali resistance. After long-term use, the mechanical strength will decrease significantly; 2) Flax fiber is difficult to disperse in alkoxy-terminated polydimethylsiloxane. It requires multiple technical means such as adding specific dispersants, adding small amounts multiple times, and continuous stirring and dispersion, which increases the processing difficulty; 3) Flax fiber is obtained from plant growth, and its thickness cannot be artificially controlled. The mechanical strength of water-blocking silicone sealant made from different batches of flax fiber may have substantial differences. Summary of the Invention

[0005] In view of the shortcomings of the prior art, one of the objectives of the present invention is to provide a water-blocking silicone sealant, and another objective of the present invention is to provide a method for preparing the water-blocking silicone sealant.

[0006] One of the objectives of this invention is achieved through the following technical solution:

[0007] A water-blocking silicone sealant is prepared from the following raw materials in parts by weight:

[0008] The composition includes 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, and 5-8 parts of swelling-absorbing fiber.

[0009] The swelling fiber is a cross-linked PVA fiber.

[0010] Specifically, the curing accelerator is ethyl acetate, the plasticizer is dimethyl silicone oil, the filler is fumed silica, the crosslinking agent is tetramethoxysilane, the catalyst is dibutyltin dilaurate acetylacetone chelate, the coupling agent is silane coupling agent KH-792, and the stabilizer is hexamethylcyclotrisilazane.

[0011] Specifically, the method for preparing the cross-linked PVA fiber includes the following steps:

[0012] S1, Dissolve PVA powder in deionized water at 90-95℃ to a concentration of 10% W / V to obtain a PVA solution;

[0013] S2, add 1% glutaraldehyde (by mass of PVA powder) and 0.5% hydrochloric acid (hydrogen chloride aqueous solution, mass fraction of 37%) to the PVA solution, stir for 30-40 min, and let stand at room temperature to defoam and obtain cross-linked PVA solution;

[0014] S3. The cross-linked PVA solution is extruded into a methanol coagulation bath through a spinneret. After 5-10 minutes, it is taken out, neutralized with an alkaline solution to neutral, washed with water, and dried with hot air at 40-50℃ to constant weight. The cross-linked PVA fibers are then cut into segments.

[0015] Specifically, the PVA (polyvinyl alcohol) has a degree of polymerization of 1700-2000 and a degree of alcoholysis ≥99%. Different PVA qualities result in significant differences in final water absorption and mechanical strength. Experiments have shown that PVA with the above parameters can produce cross-linked PVA fibers with good water absorption, acid and alkali resistance, and tensile strength.

[0016] Specifically, the spinneret orifice diameter is 0.1-0.3 mm. Fibers that are too coarse are difficult to solidify, while those that are too fine cannot generate sufficient mechanical strength.

[0017] Specifically, the cut length is 2mm ± 10%. Practical experience has shown that fibers with a length of 1-5mm are more beneficial for improving the mechanical strength of silicone sealant. Considering the error and shrinkage rate of fiber die-cutting, this invention uses a 2mm length, so that even if errors and shrinkage occur, they are unlikely to exceed the 1-5mm range. In addition, practice has shown that 2mm long fibers do not substantially affect the extrusion of silicone sealant from the caulking gun nozzle, and are also convenient for application.

[0018] In a preferred embodiment, magnetic coating layers are formed at both ends of the cross-linked PVA fibers to form a fiber web.

[0019] The second objective of this invention is achieved through the following technical solution:

[0020] A method for preparing a water-blocking silicone sealant includes the following steps:

[0021] Step 1: Stir alkoxy-terminated polydimethylsiloxane in a nitrogen-based atmosphere. During stirring, plasticizer, crosslinking agent, filler, and swelling fiber are added intermittently to the alkoxy-terminated polydimethylsiloxane. After mixing, low-boiling-point substances are removed under vacuum to obtain a gel.

[0022] Step 2: Stir the gel, adding catalyst, coupling agent, stabilizer and curing accelerator intermittently during the stirring process; after mixing, remove low-boiling-point substances under vacuum to obtain silicone sealant.

[0023] Specifically, in step one, the material temperature is controlled at 70-80℃, the feeding interval is 5-10 min, the mixing time is 50-70 min, the stirring and mixing speed is 250-350 r / min, and the vacuum degree is -0.1 MPa.

[0024] Specifically, in step two, the feeding interval is 30-60 seconds, the mixing time is 10-20 minutes, the stirring and mixing speed is 300-400 r / min, and the vacuum degree is -0.09 MPa.

[0025] The beneficial effects of this invention are as follows: cross-linked PVA fibers are used instead of natural fibers, which further improves the acid and alkali resistance and has swelling capacity. It still has the effect of swelling and water blocking without adding swelling raw materials such as sand sage gum; the thickness and length of cross-linked PVA fibers can be precisely controlled, which is conducive to improving the consistency of silicone sealant product quality. Detailed Implementation

[0026] The following is a further explanation with reference to specific implementation methods:

[0027] In all the embodiments and comparative examples, except for the swelling fiber which was prepared in-house, all other raw materials were purchased through normal channels. Specifically, the swelling fiber was a self-prepared cross-linked PVA fiber (the raw materials used to prepare the cross-linked PVA fiber were also purchased through normal channels), the curing accelerator was ethyl acetate, the plasticizer was dimethyl silicone oil, the filler was fumed silica, the cross-linking agent was tetramethoxysilane, the catalyst was a dibutyltin dilaurate acetylacetone chelate, the coupling agent was silane coupling agent KH-792, and the stabilizer was hexamethylcyclotrisilazane.

[0028] Example 1

[0029] The preparation method of cross-linked PVA fibers includes the following steps:

[0030] S1, PVA powder is dissolved in deionized water at 91℃ to a concentration of 10% W / V to obtain a PVA solution; the PVA is polyvinyl alcohol with a degree of polymerization of 1700±5 and a degree of alcoholysis of 99%, purchased from Sinopec Sichuan Vinylon Plant (the same below).

[0031] S2, add 1% glutaraldehyde (by mass of PVA powder) and 0.5% hydrochloric acid (hydrogen chloride aqueous solution, mass fraction of 37%) to the PVA solution, stir for 30-40 min, and let stand at room temperature to defoam and obtain cross-linked PVA solution;

[0032] S3, the cross-linked PVA solution is extruded into a methanol coagulation bath through a spinneret with an orifice diameter of 0.1 mm. After 5 minutes, the solution is removed and neutralized to neutral. The solution is washed with water, dried with hot air at 40°C to constant weight, and cut into segments to obtain cross-linked PVA fibers. The length of the cut segments is 2 mm ± 10%.

[0033] The preparation method of water-blocking silicone sealant includes the following steps:

[0034] Step 1: Weigh out 80 parts by weight of alkoxy-terminated polydimethylsiloxane, 30 parts by weight of plasticizer, 15 parts by weight of filler, 3 parts by weight of crosslinking agent, 1.5 parts by weight of curing accelerator, 0.5 parts by weight of catalyst, 0.5 parts by weight of coupling agent, 0.5 parts by weight of stabilizer and 5 parts by weight of swelling fiber.

[0035] Alkoxy-terminated polydimethylsiloxane was stirred in a nitrogen-based atmosphere. During stirring, plasticizer, crosslinking agent, filler, and swelling fiber were intermittently added to the alkoxy-terminated polydimethylsiloxane. After mixing, low-boiling substances were removed under vacuum to obtain a gel. The material temperature was controlled at 70℃, the feeding interval was 5 min, the mixing time was 50 min, the stirring and mixing speed was 250 r / min, and the vacuum degree was -0.1 MPa.

[0036] Step 2: Stir the gel, adding catalyst, coupling agent, stabilizer and curing accelerator intermittently during the stirring process; after mixing, remove low-boiling-point substances under vacuum to obtain silicone sealant; the feeding interval is 30s, the mixing time is 10min, the stirring and mixing speed is 300r / min, and the vacuum degree is -0.09MPa.

[0037] Example 2

[0038] The preparation method of cross-linked PVA fibers includes the following steps:

[0039] S1, Dissolve PVA powder in deionized water at 95℃ to a concentration of 10% W / V to obtain a PVA solution;

[0040] S2, add 1% glutaraldehyde (by mass of PVA powder) and 0.5% hydrochloric acid (hydrogen chloride aqueous solution, mass fraction of 37%) to the PVA solution, stir for 40 min, and let stand at room temperature to defoam and obtain cross-linked PVA solution;

[0041] S3, the cross-linked PVA solution is extruded into a methanol coagulation bath through a spinneret with an orifice diameter of 0.3 mm. After 10 min, the solution is removed and neutralized to neutral. The solution is washed with water, dried with hot air at 50°C to constant weight, and cut into segments to obtain cross-linked PVA fibers. The length of the cut segments is 2 mm ± 10%.

[0042] The preparation method of water-blocking silicone sealant includes the following steps:

[0043] Step 1: Weigh out 90 parts by weight of alkoxy-terminated polydimethylsiloxane, 50 parts by weight of plasticizer, 35 parts by weight of filler, 8 parts by weight of crosslinking agent, 3.5 parts by weight of curing accelerator, 1 part by weight of catalyst, 1 part by weight of coupling agent, 2 parts by weight of stabilizer and 8 parts by weight of swelling fiber.

[0044] Alkoxy-terminated polydimethylsiloxane was stirred in a nitrogen-based atmosphere. During stirring, plasticizer, crosslinking agent, filler, and swelling fiber were added to the alkoxy-terminated polydimethylsiloxane at intervals. After mixing, low-boiling substances were removed under vacuum to obtain a gel. The material temperature was controlled at 80℃, the feeding interval was 10 min, the mixing time was 70 min, the stirring and mixing speed was 350 r / min, and the vacuum degree was -0.1 MPa.

[0045] Step 2: Stir the gel, adding catalyst, coupling agent, stabilizer and curing accelerator intermittently during the stirring process; after mixing, remove low-boiling-point substances under vacuum to obtain silicone sealant; the feeding interval is 60s, the mixing time is 20min, the stirring and mixing speed is 400r / min, and the vacuum degree is -0.09MPa.

[0046] Example 3

[0047] The preparation method of cross-linked PVA fibers includes the following steps:

[0048] S1, Dissolve PVA powder in deionized water at 92℃ to a concentration of 10% W / V to obtain a PVA solution;

[0049] S2, add 1% glutaraldehyde (by mass of PVA powder) and 0.5% hydrochloric acid (hydrogen chloride aqueous solution, mass fraction of 37%) to the PVA solution, stir for 35 min, and let stand at room temperature to defoam and obtain cross-linked PVA solution;

[0050] S3, the cross-linked PVA solution is extruded into a methanol coagulation bath through a spinneret with an orifice diameter of 0.2 mm. After 7 minutes, the solution is removed and neutralized to neutral. The solution is washed with water, dried with hot air at 45°C to constant weight, and cut into segments to obtain cross-linked PVA fibers. The length of the cut segments is 2 mm ± 10%.

[0051] The preparation method of water-blocking silicone sealant includes the following steps:

[0052] Step 1: Weigh out 85 parts by weight of alkoxy-terminated polydimethylsiloxane, 40 parts by weight of plasticizer, 20 parts by weight of filler, 5 parts by weight of crosslinking agent, 2 parts by weight of curing accelerator, 0.7 parts by weight of catalyst, 0.7 parts by weight of coupling agent, 1 part by weight of stabilizer and 6 parts by weight of swelling fiber.

[0053] Alkoxy-terminated polydimethylsiloxane was stirred in a nitrogen-based atmosphere. During stirring, plasticizer, crosslinking agent, filler, and swelling fiber were intermittently added to the alkoxy-terminated polydimethylsiloxane. After mixing, low-boiling substances were removed under vacuum to obtain a gel. The material temperature was controlled at 75℃, the feeding interval was 7 min, the mixing time was 60 min, the stirring and mixing speed was 300 r / min, and the vacuum degree was -0.1 MPa.

[0054] Step 2: Stir the gel, adding catalyst, coupling agent, stabilizer and curing accelerator intermittently during the stirring process; after mixing, remove low-boiling-point substances under vacuum to obtain silicone sealant; the feeding interval is 40s, the mixing time is 15min, the stirring and mixing speed is 350r / min, and the vacuum degree is -0.09MPa.

[0055] Example 4

[0056] The only difference between this embodiment and Embodiment 3 is that magnetic coating layers are formed at both ends of the cross-linked PVA fibers.

[0057] Comparative Example 1

[0058] The only difference between this embodiment and Embodiment 3 is that the cross-linked PVA fibers are replaced with ordinary PVA fibers of equal weight and the same size (purchased from Shandong Chuhe New Materials Co., Ltd.).

[0059] Comparative Example 2

[0060] The technical solution described in Example 3 of the Chinese patent "A silicone sealant containing natural fibers and its preparation method and application"

[0061] Dimensional stability test

[0062] 1. Experimental objective: To verify that the silicone sealant obtained by this invention can maintain its dimensions well under freezing, soaking in water, and air-drying conditions.

[0063] 2. Experimental Method: The silicone sealants obtained in Examples 1-4 and Examples 1-2 were left to stand for 7 days and then formed into cubes with dimensions of 5cm each. These cubes were then subjected to three steps: freezing, soaking in water, and air drying. The height of each silicone sealant cube was measured after each step. Freezing involved placing the cube at -2℃ for 8 hours; soaking in water involved immersing it in clean water at 2℃ for 8 hours; and air drying involved blowing the cube at 25℃ with a wind speed of 6m / s for 8 hours. The experiment was repeated 9 times, and the average values ​​were recorded.

[0064] 3. Experimental results are shown in Table 1.

[0065] Table 1 Dimension Statistics

[0066]

[0067] As shown in Table 1, the shrinkage of Examples 1-3 of the present invention after freezing is slightly higher than that of the prior art (Comparative Example 2). However, considering that the present invention omits the sand sage glue and the shrinkage rate is less than 15%, this defect is acceptable. Furthermore, the silicone sealant obtained by the present invention has a low expansion rate after soaking in water, which, compared to the prior art, prevents the silicone sealant from damaging the window frame structure due to excessive expansion when used for water sealing. Additionally, comparing Examples 3 and 4 reveals that the magnetic coating layer formed at both ends of the cross-linked PVA fibers can further improve the dimensional stability of the silicone sealant during freezing and soaking in water, but the improvement is not significant. Therefore, the present invention can achieve dimensional stability even without using the magnetic coating layer technology.

[0068] Acid resistance test

[0069] 1. Experimental objective: To verify that the silicone sealant obtained by this invention can maintain good dimensional stability even when exposed to an acidic environment for a long time.

[0070] 2. Experimental Method: The silicone sealants obtained in Examples 1-4 and Comparative Examples 1-2 were left to stand for 7 days and then formed into cubes with dimensions of 5 cm in length, width, and height. These cubes were then immersed in 8% hydrochloric acid for 30 days, rinsed three times with water, blown at 6 m / s wind speed for 8 hours at 25°C and 60% relative humidity, and refrigerated at 2°C for 8 hours before measuring their height. The experiment was repeated 9 times, and the average values ​​were recorded.

[0071] 3. Experimental results, as shown in Table 2.

[0072] Table 2. Height Statistics After Refrigeration

[0073]

[0074] As shown in Table 2, the silicone sealant obtained by this invention still exhibits superior dimensional stability after acid immersion, while Comparative Examples 1 and 2, which use ordinary PVA fibers or flax fibers, showed a significant decrease in dimensional stability after acid immersion. In other words, this invention maintains superior dimensional stability even after being subjected to high-intensity and prolonged acid rain erosion.

[0075] Water blocking experiment

[0076] 1. Experimental objective: To verify whether the silicone sealant obtained by this invention has water-blocking ability.

[0077] 2. Experimental method: Examples 1-4 were filled into the gap between the standard single window frame (60cm*90cm) and the experimental wall. After standing for 7 days and visually observing that there was no gap, the experimental wall was sent to a cold storage at -2℃ for 8 hours. Then, the experimental wall was taken out and sprayed with water (tap water) on one side for 2 hours. After that, the other side of the experimental wall was visually observed to see if there was water seepage.

[0078] 3. Experimental results, as shown in Table 3.

[0079]

[0080] Experiments have shown that the silicone sealant obtained by this invention still retains its water-blocking ability in cool weather.

[0081] The embodiments and descriptions above are merely illustrative of the principles and preferred embodiments of the present invention. Various changes and modifications may be made to the present invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed.

Claims

1. A water-blocking silicone sealant, characterized in that, It is prepared from the following parts by weight of raw materials: The composition includes 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, and 5-8 parts of swelling-absorbing fiber. The swelling fiber is a cross-linked PVA fiber; the two ends of the cross-linked PVA fiber are not provided with magnetic coating layers. The method for preparing the cross-linked PVA fiber includes the following steps: S1, Dissolve PVA powder in deionized water at 90-95℃ to a concentration of 10% W / V to obtain a PVA solution; S2, add 1% glutaraldehyde and 0.5% hydrochloric acid (by weight of PVA powder) to the PVA solution, stir for 30-40 minutes, and let stand at room temperature to defoam and obtain cross-linked PVA solution; S3, the cross-linked PVA solution is extruded into a methanol coagulation bath through a spinneret, and after 5-10 minutes it is taken out, neutralized to neutral with an alkaline solution, washed with water, dried with hot air at 40-50℃ to constant weight, and cut into segments to obtain cross-linked PVA fibers. The PVA has a degree of polymerization of 1700-2000 and a degree of alcoholysis ≥99%; The spinneret orifice diameter is 0.1-0.3 mm; The length of the cut segment is 2mm ± 10%.

2. The water-blocking silicone sealant according to claim 1, characterized in that: The curing accelerator is ethyl acetate, the plasticizer is dimethyl silicone oil, the filler is fumed silica, the crosslinking agent is tetramethoxysilane, the catalyst is dibutyltin dilaurate acetylacetone chelate, the coupling agent is silane coupling agent KH-792, and the stabilizer is hexamethylcyclotrisilazane.

3. A method for preparing the water-blocking silicone sealant as described in claim 2, characterized in that, Includes the following steps: Step 1: Stir alkoxy-terminated polydimethylsiloxane in a nitrogen-based atmosphere. During stirring, plasticizer, crosslinking agent, filler, and swelling fiber are added intermittently to the alkoxy-terminated polydimethylsiloxane. After mixing, low-boiling-point substances are removed under vacuum to obtain a gel. Step 2: Stir the gel, adding catalyst, coupling agent, stabilizer and curing accelerator intermittently during the stirring process; after mixing, remove low-boiling-point substances under vacuum to obtain silicone sealant.

4. The method for preparing the water-blocking silicone sealant according to claim 3, characterized in that: In step one, the material temperature is controlled at 70-80℃, the feeding interval is 5-10 min, the mixing time is 50-70 min, the stirring and mixing speed is 250-350 r / min, and the vacuum degree is -0.1 MPa.

5. The method for preparing the water-blocking silicone sealant according to claim 4, characterized in that: In step two, the feeding interval is 30-60 seconds, the mixing time is 10-20 minutes, the stirring and mixing speed is 300-400 r / min, and the vacuum degree is -0.09 MPa.

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