Transparent structural adhesive and method of making and use thereof

Abstract

The application discloses a transparent structural adhesive as well as a preparation method and application thereof, and belongs to the technical field of polymers. The transparent structural adhesive comprises the following components in parts by weight: 100 parts of hydroxyl-terminated polydimethylsiloxane, 10-30 parts of dimethyl silicone oil, 0.5-2 parts of mercapto silicone oil, 15-30 parts of a filler, 3.5-5.5 parts of a crosslinking agent, 1-3 parts of a coupling agent and 0.1-0.3 parts of a catalyst. The transparent structural adhesive has excellent yellowing resistance and bonding strength. The sulfur element of the mercapto silicone oil and the tin element of the catalyst form a complex, the curing speed of the structural adhesive can be adjusted, the structural adhesive is prevented from cracking due to wind pressure in the initial stage of curing because elasticity has not been established, the structural adhesive is cured while the elasticity is established, cracking does not occur under wind pressure, in the curing process, the mercapto group forms hydrogen bonds with the hydroxyl-terminated polydimethylsiloxane and the crosslinking agent, the hydrogen bonds can resist the action of a part of wind pressure, the probability of cracking is greatly reduced, and the adhesive effect is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high polymer materials, in particular to a transparent structural adhesive and a preparation method and application thereof. BACKGROUND

[0002] The transparent structural adhesive is a material used for filling, sealing and bonding. Due to its high transparency, lightweight and plasticity, it is increasingly widely used in the fields of building, automobile and electronics in the context of people's increasing pursuit of aesthetics and safety.

[0003] However, the transparent structural adhesive also has some problems in practical application. For example, it is prone to yellowing under the action of light, heat and ultraviolet rays, which is mainly caused by the reaction of active hydrogen on the amino group. Moreover, the yellowing is more obvious on the transparent adhesive than on the calcium carbonate system. In addition, due to the influence of air silicon, the adhesion of the transparent structural adhesive, especially the water immersion and water ultraviolet adhesion, will have more or less interface damage. Furthermore, the transparent structural adhesive is mainly used for structural bonding of glass ribs and glass panels in full-glass curtain walls. When the initial strength is not established, the large glass plate will shake under the influence of wind pressure, which may cause cracking of the structural adhesive and affect the overall structural safety and aesthetics.

[0004] CN114085641A discloses a silicone sealant. However, the compatibility of the crosslinking agent with alpha, omega-dihydroxypolydimethylsiloxane and dimethyl silicone oil is not good, and oil bleeding phenomenon is easy to occur. The oil bleeding is improved by adding branched silicone oil, but the adhesion is insufficient, and the sealant is prone to yellowing under the action of light, heat and ultraviolet rays.

[0005] Therefore, the present application is proposed. SUMMARY

[0006] The present application aims to overcome the deficiencies in the prior art and provides a transparent structural adhesive and a preparation method and application thereof. The transparent structural adhesive has excellent yellowing resistance and adhesion strength.

[0007] To achieve the above-mentioned purpose, the technical solution adopted by the present application is as follows:

[0008] A transparent structural adhesive comprises the following components by weight: 100 parts of hydroxyl-terminated polydimethylsiloxane, 10-30 parts of dimethyl silicone oil, 0.5-2 parts of mercaptosilicone oil, 15-30 parts of filler, 3.5-5.5 parts of crosslinking agent, 1-3 parts of coupling agent, and 0.1-0.3 parts of catalyst.

[0009] The present application combines the above various raw materials in a specific ratio to obtain a transparent structural adhesive with excellent yellowing resistance and bonding strength. The sulfur element in the mercaptosilicone oil forms a complex with the tin element in the catalyst, which can adjust the curing speed of the structural adhesive, avoid cracking caused by wind pressure due to the lack of established elasticity at the initial stage of curing, and enable the establishment of elasticity during curing, so that cracking does not occur when wind pressure occurs. During the curing process, the mercapto group forms a hydrogen bond with the hydroxyl-terminated polydimethylsiloxane and the crosslinking agent, forming a strong chemical bond that can resist a portion of the wind pressure, greatly reducing the probability of cracking and improving the adhesion between the transparent structural adhesive and the substrate. The dimethyl silicone oil can effectively adjust the viscosity of the system, improve the compatibility of the formula, improve the curing performance and processing performance of the transparent structural adhesive, improve the wettability and adhesion of the structural adhesive to the substrate, and enable it to better adhere to the substrate surface. The mercaptosilicone oil can better improve the curing speed of the system and better establish elasticity, improve the permeability and filling property of the structural adhesive, better fill small gaps and holes, and improve the adhesive effect.

[0010] The present inventors have found that the use amount of the mercaptosilicone oil and the dimethyl silicone oil has a significant effect on the results. By controlling the use amount of both within the scope of the present application, the curing speed is effectively improved, the establishment of elasticity is accompanied by curing, the permeability and filling property of the structural adhesive are improved, small gaps and holes can be better filled, and the adhesive effect is improved. If the use amount of both deviates from the scope of the present application, either the surface drying speed is too fast and the glue cannot be scraped in time, or the elasticity cannot be established at the same time as curing, which can easily lead to cracking, or even normal curing cannot be achieved.

[0011] The use amount of the dimethyl silicone oil is 10-30 parts, for example, it can be 10 parts, 12 parts, 15 parts, 18 parts, 20 parts, 22 parts, 25 parts, 28 parts, 30 parts, or a range formed by any two of the above values.

[0012] The use amount of the mercaptosilicone oil is 0.5-2 parts, for example, it can be 0.5 parts, 0.6 parts, 0.8 parts, 1 part, 1.2 parts, 1.5 parts, 1.8 parts, 2 parts, or a range formed by any two of the above values.

[0013] The use amount of the filler is 15-30 parts, for example, it can be 15 parts, 18 parts, 20 parts, 22 parts, 25 parts, 28 parts, 30 parts, or a range formed by any two of the above values.

[0014] The use amount of the crosslinking agent is 3.5-5.5 parts, for example, it can be 3.5 parts, 3.8 parts, 4 parts, 4.5 parts, 5 parts, 5.5 parts, or a range formed by any two of the above values.

[0015] The amount of the coupling agent is 1-3 parts, for example, 1 part, 1.2 parts, 1.5 parts, 1.8 parts, 2 parts, 2.2 parts, 2.5 parts, 2.8 parts, 3 parts, or a range defined by any two of the above values.

[0016] The amount of the catalyst is 0.1-0.3 parts, for example, 0.1 part, 0.12 part, 0.15 part, 0.18 part, 0.2 part, 0.22 part, 0.25 part, 0.3 part, or a range defined by any two of the above values.

[0017] As a preferred embodiment of the present application, the transparent structural adhesive comprises the following components by weight: 100 parts of hydroxyl-terminated polydimethylsiloxane, 15-25 parts of dimethyl silicone oil, 0.8-1.5 parts of mercapto silicone oil, 15-30 parts of filler, 3.5-5.5 parts of crosslinking agent, 1-3 parts of coupling agent, and 0.1-0.3 parts of catalyst. When the amount of each raw material is controlled within the above range, the adhesive has better performance and can effectively improve the bonding performance.

[0018] As a preferred embodiment of the present application, the weight ratio of the mercapto silicone oil to the dimethyl silicone oil is 1:(8-35).

[0019] As a preferred embodiment of the present application, the weight ratio of the mercapto silicone oil to the dimethyl silicone oil is 1:(11-23), for example, 1:11, 1:12, 1:15, 1:17, 1:18, 1:20, 1:22, 1:23, or a range defined by any two of the above values. The inventors of the present application have found that, when the amount of the mercapto silicone oil and the dimethyl silicone oil is controlled within the range of the present application, the curing speed can be improved, the elasticity can be established during curing, the permeability and the filling property of the structural adhesive can be improved, the adhesive can better fill the tiny gaps and holes, and the adhesive effect can be improved.

[0020] As a preferred embodiment of the present application, the viscosity of the hydroxyl-terminated polydimethylsiloxane at 25℃ is 20000-200000 mPa·s, for example, 20000 mPa·s, 40000 mPa·s, 50000 mPa·s, 60000 mPa·s, 80000 mPa·s, 100000 mPa·s, 120000 mPa·s, 150000 mPa·s, 180000 mPa·s, 200000 mPa·s, or a range defined by any two of the above values.

[0021] As a preferred embodiment of the present application, the viscosity of the hydroxyl-terminated polydimethylsiloxane at 25℃ is 50000-80000 mPa·s.

[0022] As a preferred embodiment of the present application, the thiol group content of the thiol group-containing silicone oil is 3-6 wt%, for example, it can be 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, 5 wt%, 5.5 wt%, 6 wt%, or a range consisting of any two of the numerical values.

[0023] As a preferred embodiment of the present application, the viscosity of the thiol group-containing silicone oil at 25°C is 10-20 mPa.s, for example, it can be 10 mPa.s, 12 mPa.s, 15 mPa.s, 16 mPa.s, 18 mPa.s, 20 mPa.s, or a range consisting of any two of the numerical values.

[0024] The inventors of the present application have found that by using a thiol group-containing silicone oil (a silicone oil containing thiol groups in side chains) with such viscosity and such thiol group content, the elasticity can be more effectively established, the chemical bonds can be more firmly formed, the probability of cracking can be greatly reduced, and the adhesion between the transparent structural adhesive and the substrate can be improved.

[0025] As a preferred embodiment of the present application, the viscosity of the dimethyl silicone oil at 25°C is 100-5000 mPa.s, for example, it can be 100 mPa.s, 200 mPa.s, 500 mPa.s, 1000 mPa.s, 2000 mPa.s, 3000 mPa.s, 4000 mPa.s, 5000 mPa.s, or a range consisting of any two of the numerical values.

[0026] As a preferred embodiment of the present application, the filler is fumed silica, and the specific surface area of the fumed silica is 130-200 m 2 / g, for example, it can be 130 m 2 / g, 150 m 2 / g, 160 m 2 / g, 180 m 2 / g, 200 m 2 / g, or a range consisting of any two of the numerical values.

[0027] As a preferred embodiment of the present application, the catalyst is at least one of dibutyltin dilaurate, dibutyltin diacetate, or stannous octoate.

[0028] As a preferred embodiment of the present application, the crosslinking agent is at least one of methyltris(butanone oxime) silane, vinyltris(butanone oxime) silane, phenyltris(butanone oxime) silane, or methylvinylbis(butanone oxime) silane.

[0029] As a preferred embodiment of the present application, the coupling agent is an amino silane oligomer, which can effectively enhance the adhesion between the transparent structural adhesive and the substrate, form a firm chemical bond, improve the wettability and dispersibility of the system, facilitate the formation of a more uniform and dense adhesive film on the substrate surface, and improve the yellowing resistance under the premise of ensuring the adhesion, because it is an oligomer, the active hydrogen on nitrogen is reduced, which can effectively improve the yellowing resistance.

[0030] Among them, the representative amino silane oligomer is SIVO 203, 1146, Degussa SIVO 280, and at least one of them.

[0031] The present application also provides a preparation method of a transparent structural adhesive, comprising the following steps:

[0032] Mixing the hydroxyl-terminated polydimethylsiloxane, dimethyl silicone oil, mercaptosilicone oil, and crosslinking agent uniformly, stirring uniformly, then adding fillers, stirring uniformly, and finally adding the remaining materials, stirring uniformly to obtain the transparent structural adhesive.

[0033] The present application also provides an application of the transparent structural adhesive in the fields of building curtain walls, metals, ceramics, plastics, rubbers, electronic components, optical devices, or rail transit.

[0034] The present application has the following advantages: the transparent structural adhesive has excellent yellowing resistance and bonding strength, the sulfur element in the mercaptosilicone oil forms a complex with the tin element in the catalyst, which can adjust the curing speed of the structural adhesive, avoid cracking caused by wind pressure due to the lack of elasticity in the early stage of structural adhesive curing, make the curing accompanied by the establishment of elasticity, and avoid cracking under wind pressure, in the curing process, the mercapto group forms a hydrogen bond with the hydroxyl-terminated polydimethylsiloxane and the crosslinking agent, which can resist part of the wind pressure and greatly reduce the probability of cracking; the dimethyl silicone oil can effectively adjust the viscosity of the system, improve the compatibility of the formula, improve the curing performance and processing performance of the transparent structural adhesive, improve the wettability and adhesion of the structural adhesive to the substrate, make it better adhere to the substrate surface, and make the mercaptosilicone oil better improve the curing speed of the system and better establish the elasticity, improve the permeability and filling property of the structural adhesive, better fill the small gaps and holes, and improve the adhesive effect. DETAILED DESCRIPTION

[0035] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of the present application.

[0036] In the present application, the technical features described in an open way include both the closed technical solutions consisting of the listed features and the open technical solutions containing the listed features.

[0037] In the present application, if no special description is made, the numerical interval is regarded as continuous and includes the minimum value and the maximum value of the range and each value between the minimum value and the maximum value. Further, when the range refers to an integer, each integer between the minimum value and the maximum value of the range is included. In addition, when multiple ranges are provided to describe a feature or a property, the ranges can be combined. In other words, unless otherwise specified, all the ranges disclosed herein should be understood as including any and all sub-ranges falling within the range.

[0038] In the present application, the specific dispersion and stirring treatment methods are not particularly limited.

[0039] Unless otherwise specified, the components and raw materials used in the embodiments and comparative examples of the present application are commercially available raw materials and instruments, and the components and raw materials used in each parallel experiment are the same.

[0040] The raw materials used in the embodiments and comparative examples are described as follows:

[0041] Hydroxyl-terminated polydimethylsiloxane: viscosity at 25℃ is 80000 mPa.s, Xin'an Chemical, brand RTV-107-8.

[0042] Dimethyl silicone oil-1: viscosity at 25℃ is 100 mPa.s, brand 201-100.

[0043] Dimethyl silicone oil-2: viscosity at 25℃ is 1000 mPa.s, brand 201-1000.

[0044] Mercapto silicone oil-1: viscosity at 25℃ is 20 mPa.s, mercapto content is 6wt%, Shanghai Huiyan New Material, brand HY-2001-B.

[0045] Mercapto silicone oil-2: viscosity at 25℃ is 10 mPa.s, mercapto content is 3wt%, Shanghai Huiyan New Material, brand HY-2001-A.

[0046] Mercaptosilicone oil-3: viscosity at 25℃ is 100 mpa.s, mercaptogroup content is 8wt%, Gardner Reagent, grade: JD200706090549.

[0047] Mercaptosilicone oil-4: viscosity at 25℃ is 500 mpa.s, mercaptogroup content is 3wt%, Gardner Reagent, grade: JD200305111147.

[0048] Aminosilicone oil: Shin-Etsu Group, grade: KF-8010.

[0049] Hydroxysilicone oil: Shin-Etsu Group, grade: X-22-4039.

[0050] Coupling agent-1: aminosilane oligomer, Wacker, SIVO 203.

[0051] Coupling agent-2: silane coupling agent KH792, commonly commercially available.

[0052] Filler: fumed silica, specific surface area 180 m 2 / g, commonly commercially available.

[0053] Catalyst: dibutyl tin dilaurate, commonly commercially available.

[0054] Crosslinking agent: methyltris (butylketoximino) silane, commonly commercially available.

[0055] Examples 1-14, Comparative Examples 1-6

[0056] The formulations of the transparent structural adhesives of Examples 1-14, Comparative Examples 1-6 are shown in Tables 1 and 2 (all in parts by weight).

[0057] The preparation method of the transparent structural adhesives of Examples 1-14, Comparative Examples 1-6 all includes the following steps:

[0058] Mix the hydroxyl-terminated polydimethylsiloxane, dimethyl silicone oil, mercaptosilicone oil (when the comparative example does not contain mercaptosilicone oil, other silicone oil can be used to replace it in equal amount), crosslinking agent uniformly, stir uniformly, then add the filler, stir uniformly, finally add the remaining materials, stir uniformly, to obtain the transparent structural adhesive.

[0059] Table 1

[0060]

[0061]

[0062] Table 2

[0063]

[0064] Performance test

[0065] Yellowing resistance: the sealant is made into a strip, and after curing at room temperature for 7 days, it is treated in a 100℃ oven, and the yellowing of the sealant is observed.

[0066] Strength, elongation: tested according to 6.8.4 in GB 16776-2005.

[0067] Cracking resistance: the sealant is made into a 3*10*6mm sample, and after curing for 24h, it is subjected to tensile and bending, repeated for 5 times, and the cracking is observed.

[0068] Table 3

[0069]

[0070]

[0071] As can be seen from Table 3, the transparent structural adhesive described in the application has excellent yellowing resistance, bonding strength and mechanical properties.

[0072] As can be seen from Comparative Examples 1-5 and Examples 6-9, the application further controls the weight ratio of the mercapto silicone oil and the dimethyl silicone oil to be 1:(8-35) on the basis of controlling the raw materials, further improving the bonding strength and mechanical properties.

[0073] As can be seen from Comparative Examples 1-3 and Examples 4-5, the application further controls the weight ratio of the mercapto silicone oil and the dimethyl silicone oil to be 1:(11-23) on the basis of controlling the raw materials, further improving the bonding strength and mechanical properties.

[0074] The application further controls the weight ratio of the mercapto silicone oil and the dimethyl silicone oil to be 1:(8-35) on the premise of controlling the amount of each raw material within the range of the application (100 parts of hydroxyl-terminated polydimethylsiloxane, 10-30 parts of dimethyl silicone oil, 0.5-2 parts of mercapto silicone oil, 15-30 parts of filler, 3.5-5.5 parts of crosslinking agent, 1-3 parts of coupling agent, 0.1-0.3 parts of catalyst), and a transparent structural adhesive with a tensile strength of 0.67-0.78MPa, an elongation of 232-261%, and a cracking degree of 10.2-16.0% is prepared.

[0075] As can be seen from Comparative Examples 1 and 11 and Examples 12-13, by using a mercapto silicone oil with a mercapto content of 3-6wt% and a viscosity of 10-20mPa·s at 25℃, the bonding strength and mechanical properties are further improved.

[0076] As can be seen from the comparison between Comparative Example 1 and Example 14, the amino silane oligomer used in the present application significantly improves the yellowing resistance.

[0077] As can be seen from the comparison between Comparative Example 1 and Comparative Examples 1-2, the present application significantly improves the bonding strength and mechanical properties by using dimethyl silicone oil and mercapto silicone oil in combination, and the combination of the two has a significant synergistic effect, and if either of them is missing, the effect will be significantly reduced, and even cannot be cured.

[0078] As can be seen from the comparison between Comparative Example 1 and Comparative Examples 3-4, the present application significantly improves the bonding strength and mechanical properties by controlling the amount of dimethyl silicone oil and mercapto silicone oil within the range of the present application.

[0079] As can be seen from the comparison between Comparative Example 1 and Comparative Examples 5-6, the mercapto silicone oil of the present application is irreplaceable, and if other types of silicone oil are used to replace the mercapto silicone oil, the bonding strength and mechanical properties will be significantly reduced.

[0080] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application and not to limit the scope of protection of the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present application.

Claims

1. A transparent structural adhesive, characterized in that, It comprises the following components in parts by weight: 100 parts hydroxyl-terminated polydimethylsiloxane, 10-30 parts dimethyl silicone oil, 0.5-2 parts mercapto silicone oil, 15-30 parts filler, 3.5-5.5 parts crosslinking agent, 1-3 parts coupling agent, and 0.1-0.3 parts catalyst; The weight ratio of the mercapto silicone oil to the dimethyl silicone oil is 1:(11-23); The mercaptosilicone oil has a mercapto content of 3-6 wt% and a viscosity of 10-20 mPa·s at 25°C. The catalyst is at least one of dibutyltin dilaurate, dibutyltin diacetate, or stannous octoate. The coupling agent is an aminosilane oligomer.

2. The transparent structural adhesive according to claim 1, characterized in that, The viscosity of the hydroxyl-terminated polydimethylsiloxane at 25°C is 20,000–200,000 mPa·s.

3. The transparent structural adhesive according to claim 1, characterized in that, The viscosity of the hydroxyl-terminated polydimethylsiloxane at 25°C is 50,000–80,000 mPa·s.

4. The transparent structural adhesive according to claim 1, characterized in that, The viscosity of the dimethyl silicone oil at 25°C is 100–5000 mPa·s.

5. The transparent structural adhesive according to claim 1, characterized in that, Satisfy at least one of the following (a) to (b): (a) The filler is fumed silica, and the specific surface area of ​​the fumed silica is 130–200 m². 2 / g; (b) The crosslinking agent is at least one of methyl tributanone oxime silane, vinyl tributanone oxime silane, phenyl tributanone oxime silane, and methyl vinyl dibutanone oxime silane.

6. The method for preparing the transparent structural adhesive according to any one of claims 1 to 5, characterized in that, Includes the following steps: Hydroxyl-terminated polydimethylsiloxane, dimethyl silicone oil, mercapto silicone oil, and crosslinking agent are mixed evenly and stirred until homogeneous. Then, filler is added and stirred until homogeneous. Finally, the remaining materials are added and stirred until homogeneous to obtain a transparent structural adhesive.

7. The application of the transparent structural adhesive according to any one of claims 1 to 5 in building curtain walls, metals, ceramics, plastics, rubber, electronic components, optical devices, rail transportation, and automobiles.

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