Tackifier for single-component addition type thermocuring liquid silicone rubber as well as preparation method and application of tackifier

Abstract

The invention relates to the technical field of liquid silicone rubber, and particularly discloses a tackifier for single-component addition type thermosetting liquid silicone rubber as well as a preparation method and application of the tackifier. The hydrogen-containing siloxane tackifier with epoxy and benzene ring groups is designed and synthesized through heating reaction of a compound with epoxy, benzene ring and vinyl and hydrogen-containing siloxane under the action of a platinum catalyst, and the tackifier is good in compatibility with silicone rubber, simple to prepare and convenient to apply; when being added into the single-component addition type liquid organic silicon rubber, the silicon rubber can react with active groups on the surface of a polar base material to form a firm bonding effect during high-temperature heating, the conditions of oil leakage and adhesion are avoided during compression sealing after high-temperature curing, and lossless disassembly and repair can be realized.

Description

Technical Field

[0001] The invention belongs to the field of liquid silicone rubber, and in particular relates to a single-component addition-type heat-curing liquid silicone rubber tackifier and a preparation method and application thereof. Background Art

[0002] With the rapid development of my country's industry, new energy vehicles, 5G communications, electronic appliances, photovoltaics, energy storage and other industries are booming with emerging technologies. In the industrial production process, assembly links such as shell sealing, flange sealing, flat and curved surface sealing are important components, and workpiece sealing is extremely important. Single-component addition-type silicone rubber has the characteristics of rapid curing by heating, good compression rebound, no low-molecular release, and green environmental protection due to its unique cross-linking curing mechanism. It is very suitable for CIPG sealing process (Cured-In-Place Gasket, which is a curing online forming sealing ring process, which refers to the process of first applying liquid sealant on the flange or other sealing surface, and then assembling after rapid curing to achieve single-sided bonding and double-sided compression sealing).

[0003] At present, the single-component addition-type silicone rubber has poor adhesion to metal substrates, which causes the position of the sealing strip to shift or even fall off during transportation. The simplest and most effective method is to add silane coupling agents to the system. Among conventional silane coupling agents, amino coupling agents will cause the platinum catalyst to fail and cannot be used; epoxy coupling agents cannot participate in the cross-linking reaction, and the sealant is easy to precipitate after long-term compression after curing, which is not conducive to the long-term, safe and stable operation of the internal components of the seal; although acryloxy coupling agents can participate in the cross-linking reaction, they will affect the curing speed and mechanical properties; the more active methoxy or ethoxy groups in the silane coupling agent cause the cured strip to continue to react with the substrate surface after long-term compression, resulting in adhesion, and non-destructive disassembly and repair cannot be achieved. Therefore, it is very necessary to develop a single-component addition-type heat-curing silicone rubber tackifier, which not only has excellent adhesion to the substrate after high-temperature curing, but also can achieve non-destructive disassembly and repair after long-term environmental aging.

[0004] Chinese patent CN105131291A discloses a tackifier for addition-type liquid silicone rubber and its preparation method, as well as an adhesive addition-type liquid silicone rubber containing the tackifier and its preparation method. Methyldimethoxysilane and dimethyldimethoxysilane are hydrolyzed and condensed under the catalysis of hydrochloric acid solution to obtain terminal hydroxymethylhydrogensilane, and then the terminal hydroxymethylhydrogensilane is catalyzed with γ-(2,3-epoxypropoxy)propyltrimethoxysilane and γ-(methacryloyloxy)propyltrimethoxysilane to obtain a tackifier under the catalysis of titanate. After the tackifier is used in addition-type liquid silicone rubber, it can achieve 100% cohesive failure on aluminum, glass and stainless steel, and the shear strength is up to 2.0MPa. The addition-type liquid silicone rubber in the invention technology contains alkoxy groups. After the liquid silicone rubber is cured, the alkoxy groups that have not been completely reacted in the tackifier are hydrolyzed to form silanol groups after long-term aging, which are prone to react with the contact surface, so there is a serious risk of adhesion.

[0005] Chinese patent CN113801626A discloses a method of adding titanate coupling agent and part of alkoxy tackifier to base glue in steps, adding alkoxy tackifier after obtaining prepolymer, and then preparing a one-component addition type adhesive with auxiliary agents such as hydrogen-containing polysiloxane and weakly acidic pH regulator. The tackifier needs to be used in combination with two, and the step-by-step addition process and pH adjustment are adopted, otherwise the bonding strength will be significantly reduced. The glue making process is complicated and is not conducive to industrial production.

[0006] Chinese patent CN104892942A discloses a method for preparing an addition type silicone rubber tackifier by hydrolysis and condensation using an acidic cationic resin as a catalyst: using three or more alkoxysilanes with different functionalities as raw materials, using methanol or ethanol as a solvent and controlling the degree of condensation reaction at the same time, using an acidic cationic resin as a catalyst, partially co-hydrolyzing and condensing at 40-80°C, filtering to remove the cationic resin and removing the solvent and low volatile matter under reduced pressure to obtain a colorless and transparent siloxane oligomer tackifier with a degree of polymerization of 3-6. Although the addition type silicone rubber prepared by the tackifier has good adhesion to a variety of substrates, it needs to be cured at high temperature for a long time after heating pretreatment, has poor timeliness and high energy consumption, causing great inconvenience to practical applications.

[0007] At present, there are many related inventions in China for the application of tackifiers for addition-type organic silicone rubber, but many studies focus on the bonding between silicone rubber and substrates, while ignoring the problem that silicone rubber adheres to the upper cover after long-term use and cannot be disassembled and repaired, as well as the complex manufacturing and application processes. Therefore, the invention of a tackifier that can help silicone rubber achieve excellent adhesion to the substrate after curing, and can be non-destructively disassembled and repaired after long-term environmental aging, with a simple process, can greatly increase the value of silicone rubber in industrial applications. Summary of the invention

[0008] In order to overcome the deficiencies and shortcomings of the prior art, the primary purpose of the present invention is to provide a method for preparing a one-component addition-type thermosetting liquid silicone rubber tackifier.

[0009] The second object of the present invention is to provide a one-component addition type heat-curing liquid silicone rubber tackifier prepared by the above preparation method.

[0010] The third object of the present invention is to provide the use of the above-mentioned one-component addition type heat-curing liquid silicone rubber tackifier in liquid silicone rubber.

[0011] The primary purpose of the present invention is achieved through the following technical solutions:

[0012] A method for preparing a one-component addition-type heat-curing liquid silicone rubber tackifier comprises the following steps:

[0013] (1) mixing hydrogen-containing polydimethylsiloxane, a catalyst, and an auxiliary agent A uniformly, heating for reaction, vacuum removing impurities, and filtering to obtain a liquid B;

[0014] (2) After the liquid B is cooled to room temperature, activated carbon is added, stirred and adsorbed, and then filtered to obtain a thickener.

[0015] Preferably, the hydrogen-containing polydimethylsiloxane in step (1) is end-side hydrogen-containing polydimethylsiloxane (abbreviated as: end-side hydrogen-containing silicone oil), and the hydrogen content of the hydrogen-containing polydimethylsiloxane is 0.36% to 0.75%.

[0016] Preferably, the catalyst in step (1) is at least one of platinum-1,3-divinyltetramethyldisiloxane complex, bis(1,3-divinyl-1,1,3,3-tetramethyldisiloxane) platinum, platinum-1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane complex, and chloroplatinic acid vinyl complex methyl phthalate solution, and the platinum content is 1000-5000ppm. The catalyst can catalyze the reaction of hydrogen-containing polydimethylsiloxane and auxiliary agent A, so that auxiliary agent A reacts with Si-H groups of hydrogen-containing polydimethylsiloxane to connect auxiliary agent A to hydrogen-containing polydimethylsiloxane. In the present invention, the catalyst platinum content of step (1) can be selected from the range of 1000 to 5000 ppm, for example, 1000 ppm, 1500 ppm, 2000 ppm, 2500 ppm, 3000 ppm, 3500 ppm, 4000 ppm, 4500 ppm, 5000 ppm, etc., but is not limited to the listed catalyst platinum contents.

[0017] Preferably, the auxiliary agent A in step (1) is at least one of 4-(ethylene oxide) styrene, bisphenol A bisallyl ether, 4-vinyl-methyl benzoate, and (4-vinylphenyl) trimethoxysilane. The molecular structure of the auxiliary agent A contains a vinyl group, an epoxy group, and a benzene ring group. The auxiliary agent A is connected to the hydrogen-containing polydimethylsiloxane through the vinyl group in the molecular structure of the auxiliary agent A so that the tackifier has an epoxy group and a benzene ring group. If the tackifier still retains the vinyl group, when the tackifier is used in a one-component addition type heat-curing liquid silicone rubber, these vinyl groups will affect the vulcanization speed of the silicone rubber. For example, when the auxiliary agent A is bisphenol A bisallyl ether, the vinyl group will be retained on the tackifier.

[0018] Preferably, in step (1), the molar ratio of hydrogenated polydimethylsiloxane: auxiliary agent A is 1:1 to 3. By controlling the molar ratio of hydrogenated polydimethylsiloxane to auxiliary agent A, it is ensured that auxiliary agent A is connected to the terminal hydrogen of hydrogenated polydimethylsiloxane, and the side hydrogen of hydrogenated polydimethylsiloxane is retained, and the final obtained tackifier retains the side chain Si-H. In the present invention, the embodiment can select the dosage ratio of hydrogenated polydimethylsiloxane and auxiliary agent A in step (1) from the molar ratio range of 1:1 to 3, such as 1:1, 1:1.5, 1:2, 1:2.5, 1:3, etc., but is not limited to these listed molar ratios. Preferably, the molar ratio of hydrogenated polydimethylsiloxane: auxiliary agent A is 1:1 to 2.5. When the amount of auxiliary agent A is too low, too little auxiliary agent A will be connected to the hydrogen-containing polydimethylsiloxane, and when the amount of auxiliary agent A is too high, a large amount of side chain Si-H of the hydrogen-containing polydimethylsiloxane will also be connected to auxiliary agent A. In the present invention, the side Si-H of the hydrogen-containing polydimethylsiloxane is retained in the tackifier, and the Si-H of the tackifier can produce a cross-linking reaction with the base polymer in the one-component addition-type heat-curing liquid silicone rubber to avoid oil seepage during long-term compression.

[0019] Preferably, the temperature of the heating reaction in step (1) is 60-100°C, and the reaction time is 2-4h. In the present invention, the reaction temperature of step (1) can be selected from the range of 60-100°C, such as 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, etc., but is not limited to these listed temperature values. The preferred reaction temperature is 60-70°C, which can ensure that the auxiliary agent A is connected to the terminal hydrogen of the hydrogen-containing polydimethylsiloxane, and the side hydrogen of the hydrogen-containing polydimethylsiloxane is retained, and the resulting tackifier retains the side chain Si-H. When the temperature is further increased, it may cause the local reaction temperature to be higher, which increases the hydrogen-containing activity of the side chain of the hydrogen-containing polydimethylsiloxane, and the reaction of the vinyl group with the side chain causes the group of the auxiliary agent A to be connected to the side chain of the hydrogen-containing polydimethylsiloxane, which ultimately affects the viscosity stability of the one-component addition silicone rubber, thereby affecting the storage stability of the one-component addition silicone rubber.

[0020] Preferably, the stirring reaction time of adding activated carbon in step (2) is 8 to 24 hours. The function of activated carbon is to adsorb and remove the platinum catalyst in liquid B, thereby achieving the purpose of removing impurities.

[0021] The term "impurity removal" refers to the removal of small molecular impurities in the reaction product, which include low-ring vinyl silicone oil D3-D10 and other components. The impurity removal methods include vacuum impurity removal, activated carbon impurity removal or other conventional methods.

[0022] The preparation method of the above-mentioned tackifier adopts simple steps and easily achievable process conditions (heating, stirring, vacuum) to efficiently (short reaction time) synthesize a hydrogen-containing siloxane tackifier with epoxy and benzene ring groups.

[0023] The second object of the present invention is achieved by the following technical solutions:

[0024] A one-component addition-type heat-curing liquid silicone rubber tackifier prepared by the above preparation method has the following structural formula:

[0025]

[0026] Wherein m=1 to 8, n=8 to 30 natural numbers, and R1 is any one of the following groups:

[0027]

[0028] In some embodiments of the present invention, the above-mentioned tackifiers may be used with natural numbers of m=4-5 and n=10-23.

[0029] In some embodiments of the present invention, the main component of the tackifier is any one of the following:

[0030]

[0031]

[0032] The structural characteristics and working principle of the tackifier prepared by the present invention:

[0033] In the CIPG compression sealing application scenario, not only does the sealing material need to be firmly bonded to the sealing surface on one side to prevent displacement or even falling off, but it also needs to be easy to disassemble and non-sticky after environmental aging. This is an application contradiction that conventional one-component addition-type heat-curing liquid silicone rubber cannot solve. The one-component addition-type heat-curing liquid silicone rubber tackifier described in the present invention is a hydrogen-containing siloxane tackifier with epoxy and benzene ring groups designed and synthesized. The one-component addition-type silicone rubber prepared by this tackifier can react with the surface active groups of the substrate to form a strong bonding effect during high-temperature curing; and after curing, due to the helical curling of the molecular chain segments, the non-polar benzene ring macromolecules and the side groups can shield the polarity of the epoxy groups and the silicon oxygen bonds, the colloidal interface shows a lower surface energy, and the molecular interaction force with the bonding substrate is weak, thereby avoiding the adhesion phenomenon caused by long-term compression; Si-H in the tackifier can produce a cross-linking reaction with the base polymer to avoid long-term compression oil seepage. The use of this tackifier solves the problems of poor adhesion to the substrate, complex adhesion, and oil seepage of the traditional one-component addition-type heat-curing liquid silicone rubber.

[0034] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0035] The one-component addition-type thermosetting liquid silicone rubber tackifier prepared by the present invention has active groups that are not easily hydrolyzed and has low requirements on the storage environment. When preparing the rubber material, only the base rubber, tackifier, cross-linking agent and catalyst need to be mixed and used. The operation is simple, the production efficiency is high, and the method is suitable for industrial production.

[0036] The AL-AL shear strength measured by dispensing on the aluminum alloy shell (AL) is ≥3Mpa, and it can be disassembled after thermal aging, and the anti-adhesion level reaches MB:B-0 or above (GB / T 23982-2009). It can be seen that the silicone rubber of the present invention can be non-destructively disassembled and repaired after long-term environmental aging.

[0037] The one-component addition type heat-curing liquid silicone rubber tackifier prepared by the present invention has good compatibility with the organic silicon matrix (i.e. base rubber), and the prepared rubber material will not delaminate or leak oil after being stored at room temperature (25-30°C) for 6 months, and the viscosity change rate is less than 20%. Moreover, it only takes 10 minutes to achieve rapid curing at 150°C.

[0038] The third object of the present invention is achieved by the following technical solutions:

[0039] The above-mentioned tackifier is used as a tackifier in the preparation of liquid silicone rubber, especially in the single-component addition type heat-curing liquid silicone rubber.

[0040] The Si-H in the tackifier can produce a cross-linking reaction with the base polymer (mainly composed of vinyl silicone oil) in the one-component addition-type heat-curing liquid silicone rubber to avoid long-term compression and oil leakage. The use of this tackifier solves the problems of poor adhesion to the substrate, multiple adhesion and oil leakage of traditional one-component addition-type heat-curing liquid silicone rubber. The shear strength of the one-component addition-type liquid silicone rubber on the aluminum alloy object reaches 2.4MPa~4.1MPa, the anti-adhesion grade reaches A0~B2, and the rubber strip does not fall off and does not leak oil. DETAILED DESCRIPTION

[0041] The present invention is specifically described below through examples. It is necessary to point out that the following examples are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Those skilled in the art in this field can make some non-essential improvements and adjustments based on the contents of the present invention.

[0042] Tackifier Example 1:

[0043] (1) In a three-necked flask equipped with a thermometer, a condenser, and a mechanical stirring device, 83 g of end-side hydrogenated silicone oil with a hydrogen content of 0.6% (m=5, n=11) and 0.1 g of platinum-1,3-divinyltetramethyldisiloxane complex (3000 ppm) were added, and after stirring for 15 min, 20.5 g of auxiliary agent A1 (4-(epoxyethyl)styrene) (hydrogenated silicone oil: auxiliary agent A1 molar ratio is 1:2) was added, and the temperature was raised to 65°C, and the reaction was kept at this temperature for 2 h, and then the temperature was raised to 160°C and vacuumed for 3 h to remove unreacted small molecules to obtain liquid B. The reaction equation is as follows:

[0044]

[0045] Note: The following reaction mechanism is the same as C1.

[0046] (2) After liquid B was cooled to room temperature, 5 g of porous activated carbon was added, the mixture was stirred for 24 h, and the mixture was filtered three times to obtain liquid thickener C1.

[0047] Tackifier Example 2:

[0048] The difference between the preparation process and implementation case 1 is that the molar ratio of hydrogenated silicone oil: auxiliary agent A1 in step (1) is replaced with 1:1 to obtain liquid thickener C2.

[0049] Tackifier Example 3:

[0050] The difference between the preparation process and implementation case 1 is that the molar ratio of hydrogenated silicone oil: auxiliary agent A1 in step (1) is replaced with 1:3 to obtain liquid tackifier C3.

[0051] Tackifier Example 4:

[0052] The difference between the preparation process and implementation case 1 is that the auxiliary agent A1 (4-(ethylene oxide) styrene) in step (1) is replaced by an equal molar amount of auxiliary agent A2 (bisphenol A bisallyl ether) to obtain liquid tackifier C4.

[0053] Tackifier Example 5:

[0054] The difference between the preparation process and implementation case 1 is that the auxiliary agent A1 (4-(ethylene oxide) styrene) in step (1) is replaced by an equal molar amount of auxiliary agent A3 (4-vinyl-benzoic acid methyl ester) to obtain liquid thickener C5.

[0055] Tackifier Example 6:

[0056] The preparation process is similar to that of Example 1, except that the equimolar amount of auxiliary agent A1 (4-(ethylene oxide) styrene) in step (1) is replaced by auxiliary agent A4 ((4-vinylphenyl) trimethoxysilane) to obtain liquid tackifier C6.

[0057] Tackifier Example 7:

[0058] The preparation process is similar to that of Implementation Example 1, except that the end-side hydrogenated silicone oil in step (1) is replaced with end-side hydrogenated silicone oil with a hydrogen content of 0.36% (m=5, n=23) (the replacement amount is calculated based on the hydrogen content equal to that of the hydrogenated silicone oil in Example 1) to obtain liquid thickener C7.

[0059] Tackifier Example 8:

[0060] The preparation process is similar to that of Implementation Example 1, except that the end-side hydrogenated silicone oil in step (1) is replaced with end-side hydrogenated silicone oil with a hydrogen content of 0.75% (m=6, n=10) (the replacement amount is calculated based on the hydrogen content equal to that of the hydrogenated silicone oil in Example 1) to obtain liquid thickener C8.

[0061] Tackifier Example 9:

[0062] (1) In a three-necked flask equipped with a thermometer, a condenser, and a mechanical stirring device, 83 g of end-side hydrogenated silicone oil with a hydrogen content of 0.6% (m=5, n=11) and 0.1 g of platinum-1,3-divinyltetramethyldisiloxane complex (3000 ppm) were added, and after stirring for 15 min, 20.5 g of auxiliary agent A1 (4-(epoxyethyl)styrene) (the molar ratio of hydrogenated silicone oil: auxiliary agent A1 is 1:2) was added, the temperature was raised to 90°C, the reaction was kept at this temperature for 2 h, and then the temperature was raised to 160°C and vacuumed for 3 h to remove unreacted small molecules to obtain Liquid B.

[0063] (2) After liquid B was cooled to room temperature, 5 g of porous activated carbon was added, the mixture was stirred for 24 h, and the mixture was filtered three times to obtain liquid thickener C9.

[0064] In order to better illustrate the present invention, the present invention uses auxiliary agent A1 and the tackifier obtained in Examples 1 to 9 to prepare a one-component addition-type liquid silicone rubber, and the one-component addition-type liquid silicone rubber is bonded to an aluminum alloy housing to test aging anti-adhesion.

[0065] The preparation method of one-component addition type liquid silicone rubber is as follows:

[0066] 40 parts of high-viscosity vinyl silicone oil with a viscosity of 120,000 mPa·s, 60 parts of low-viscosity vinyl silicone oil with a viscosity of 5,000 mPa·s, and 35 parts of 2 / g of fumed silica, 6 parts of hexamethyldisiloxane and 2 parts of deionized water are mixed uniformly in a kneader under vacuum conditions, heated to 130°C and stirred for 2 hours, heated to 180°C and stirred in a vacuum for 2 hours, cooled and ground to form a base material.

[0067] Take 70 parts of base material, 30 parts of 1000mPa·s vinyl silicone oil, 1 part of 1.0% side hydrogen-containing silicone oil, 0.1 part of 1-methyl-1-butynol, 0.2 parts of bis(3-phenyl-1-butyn-3-ol)-cyclooctane-1,5-diene platinum complex (3000ppm), respectively take tackifiers C1 to C9 and mix them uniformly to prepare a single-component addition-type liquid silicone rubber to establish silicone rubber embodiments 1 to 9 shown in Table 1, and at the same time, do not add tackifiers, add commercially available tackifiers and additives A1 to establish comparative examples 1 to 3 shown in Table 1, and the scheme is as follows Table 1:

[0068] Table 1 Preparation of one-component addition type liquid silicone rubber

[0069]

[0070] The tackifiers prepared in tackifier embodiments 1 to 9 and silicone rubber embodiments 1 to 9 prepared therefrom, as well as silicone rubber comparative examples 1 to 3 were subjected to relevant tests:

[0071] 1. Compatibility test:

[0072] Poor compatibility of additives or tackifiers with base polymers will cause oil leakage in the storage process of silicone rubber, and may also cause oil leakage after long-term compression after curing; good compatibility of additives or tackifiers with base polymers can make silicone rubber less likely to leak oil during storage, but long-term compression after curing may cause oil leakage if it does not participate in the cross-linking reaction; good compatibility of additives or tackifiers with base polymers and participation in the cross-linking reaction make silicone rubber less likely to leak oil during storage and long-term compression. Therefore, the possibility of oil leakage in silicone rubber during storage is evaluated by testing compatibility.

[0073] In order to prove the effectiveness of the reaction between 4-(epoxyethyl)styrene and end-side hydrogenated silicone oil, this project mixed vinyl silicone oil with additive A1 (4-(epoxyethyl)styrene), additive A2 (bisphenol A bisallyl ether), additive A3 (4-vinyl-methyl benzoate), additive A4 ((4-vinylphenyl)trimethoxysilane) and synthetic tackifiers C1 to C9 in a mass ratio of 1:1, let it stand for 24 hours, and then conduct compatibility test. The results are shown in Table 2:

[0074] Table 2 Compatibility test

[0075] Additives Compatibility Additives Compatibility Vinyl silicone oil + hydrogen silicone oil No stratification C3+ Vinyl Silicone Oil Layering A1+ Vinyl Silicone Oil Layering C4+ Vinyl Silicone Oil No stratification A2+ Vinyl Silicone Oil Layering C5+ Vinyl Silicone Oil No stratification A3+ Vinyl Silicone Oil Layering C6+ Vinyl Silicone Oil No stratification A4+ Vinyl Silicone Oil No stratification C7+ Vinyl Silicone Oil No stratification C1+ Vinyl Silicone Oil No stratification C8+ Vinyl Silicone Oil No stratification C2+ Vinyl Silicone Oil No stratification C9+ Vinyl Silicone Oil No stratification

[0076] When two substances are mixed, the greater the difference in structural polarity, the worse the compatibility. As can be seen from Table 2, vinyl silicone oil will not be stratified after being evenly mixed with (4-vinylphenyl)trimethoxysilane, but stratification will occur after being mixed with 4-(ethylene oxide)styrene, bisphenol A bisallyl ether, and 4-vinyl-methyl benzoate. After grafting reaction with end-side hydrogen-containing silicone oil, no stratification occurs, indicating that after the introduction of the siloxane structure, the compatibility of the additive and the silicone oil base polymer is increased, so that the tackifier can be evenly dispersed in the system, but the C3 additive introduces too much 4-(ethylene oxide)styrene, resulting in stratification after mixing with vinyl silicone oil.

[0077] 2. Curing performance comparison test:

[0078] Take 4g of the above single-component addition type silicone rubber, put it into the rotorless vulcanizer, set the mold temperature to 150°C, and the curing time to 10min. Test its curing speed at high temperature. The test results are shown in Table 3 below:

[0079] Table 3 Curing test (unit: seconds)

[0080]

[0081]

[0082] From the comparative analysis in Table 3 above, it can be seen that in Comparative Example 1, no tackifier is added, and the curing effect is better, while in Comparative Example 2, a commercially available tackifier is added, and the curing effect is better; in Comparative Example 3, the addition of auxiliary agent A1 (4-(ethylene oxide) styrene) to the one-component addition type liquid silicone rubber will cause the curing speed to slow down, while the curing speed of Example 1 is faster than that of Comparative Example 1, indicating that the addition of auxiliary agent A will cause the curing speed of the one-component addition type liquid silicone rubber to slow down, and adding the homemade tackifier obtained by grafting auxiliary agent A1 (4-(ethylene oxide) styrene) with hydrogenated silicone oil to the one-component addition type liquid silicone rubber is more conducive to curing, and the curing speed is even better than that of using a commercially available tackifier or not using a tackifier.

[0083] Since Example 4 uses tackifier C4 obtained by grafting the auxiliary agent A2 instead of A1 with hydrogen-containing silicone oil, tackifier C4 has two vinyl groups, which slows down the curing speed.

[0084] 3. Viscosity change aging test:

[0085] The single-component addition silicone rubbers of Comparative Examples 1 to 3 and Examples 1 to 9 with tackifiers added were tested for viscosity without adding catalysts and inhibitors, and the viscosity was tested after being placed at room temperature (25° C. to 30° C.) for 6 months. The test results are shown in Table 4 below:

[0086] Table 4 Viscosity test

[0087]

[0088]

[0089] As can be seen from Table 4, the viscosity of the one-component addition-type silicone rubber of each embodiment and comparative example changes little after being placed at room temperature for 6 months, indicating that the one-component addition-type silicone rubber of the embodiment and comparative example has good storage stability. Therefore, the tackifier prepared by the present invention has no negative impact on the viscosity of the one-component addition-type silicone rubber, and can maintain the good storage stability of the silicone rubber.

[0090] 4. Adhesion test and anti-adhesion test:

[0091] The shear strength of the single-component addition-type liquid silicone rubber prepared by the adhesives of Comparative Examples 1 to 3 and Examples 1 to 9 of the present invention was tested, and the adhesive strip was dispensed on the aluminum alloy housing. The size of the adhesive strip was 3±0.2 mm in width and 1.9±0.2 mm in height. The rubber strip was cured at 150°C for 30 minutes, cooled at room temperature for 24 hours, and then the upper cover was locked. The adhesion and anti-adhesion conditions after aging at 125°C for 300 hours were tested. The test results are shown in Table 5:

[0092] Table 5 Performance test results

[0093]

[0094]

[0095] It can be seen from Table 5 above that among the examples grafted with hydrogen-containing silicone oil, Example 1 has the best shear strength and the anti-adhesion grade can reach A0. The tackifier C1 of Example 1 has a longer molecular chain than 4-(epoxyethyl)styrene. After being added to the one-component addition-type liquid silicone rubber, the epoxy group is activated by high temperature and reacts with the surface active groups of the substrate to form a bond; after high-temperature aging, due to the helical curling of the molecular chain segments and the non-polar benzene ring macromolecules and side groups that can shield the polarity of the epoxy group and the silicon oxygen bond, the entire molecule is highly saturated, showing a lower surface energy, and the molecular interaction force with the substrate is weak, thereby avoiding oil seepage and adhesion phenomena caused by long-term compression.

[0096] As shown in Table 2-5, 4-(ethylene oxide)styrene has better compatibility with silicone oil after reaction and grafting with hydrogen-containing silicone oil. After adding into one-component addition-type liquid silicone rubber, it can achieve rapid curing at high temperature of 150°C and has good storage stability at room temperature. The anti-adhesion grade reaches A0 after high temperature aging compression test.

[0097] Examples 2 and 3 also use A1 to prepare the tackifier, and the rest is the same as Example 1, but the anti-adhesion grade cannot reach A0 because the molar ratio of the hydrogen-containing silicone oil and the auxiliary agent A1 is different, and the optimal molar ratio of the hydrogen-containing silicone oil and the auxiliary agent A1 is 1:2; in Example 3, the amount of A1 used is too high (the molar ratio of the hydrogen-containing silicone oil and the auxiliary agent A1 is 1:3), resulting in oil leakage in the silicone rubber.

[0098] The anti-adhesion grade of Examples 1, 4, and 9 all reaches A0, but the shear strength of Example 4 is slightly lower, while the shear strengths of Examples 1 and 9 are relatively high. This is because Examples 1 and 9 all use A1, while Example 4 uses A2, indicating that the two additives have differences in performance.

[0099] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A one-component addition type heat-curing liquid silicone rubber tackifier, characterized in that: The structure of the tackifier is as follows: Wherein m=1 to 8, n=8 to 30 natural numbers, and R1 is any one of the following groups:

2. A method for preparing a one-component addition type heat-curing liquid silicone rubber tackifier, characterized in that: The steps include: (1) mixing hydrogen-containing polydimethylsiloxane, a catalyst, and an auxiliary agent A uniformly, heating for reaction, vacuum removing impurities, and filtering to obtain a liquid B; (2) After the liquid B is cooled to room temperature, activated carbon is added, stirred and adsorbed, and then filtered to obtain a thickener.

3. The method for preparing a one-component addition type heat-curing liquid silicone rubber tackifier according to claim 2, characterized in that: The hydrogen-containing polydimethylsiloxane is a terminal hydrogen-containing polydimethylsiloxane, and the auxiliary agent A is at least one of 4-(ethylene oxide)styrene, bisphenol A bisallyl ether, 4-vinyl-benzoic acid methyl ester, and (4-vinylphenyl)trimethoxysilane.

4. The method for preparing a one-component addition type heat-curing liquid silicone rubber tackifier according to claim 3, characterized in that: The molar ratio of the hydrogen-containing polydimethylsiloxane to the auxiliary agent A is 1:1-3.

5. The method for preparing a one-component addition type heat-curing liquid silicone rubber tackifier according to claim 3, characterized in that: The molar ratio of the hydrogen-containing polydimethylsiloxane to the auxiliary agent A is 1:1 to 2.

5.

6. The method for preparing a one-component addition type heat-curing liquid silicone rubber tackifier according to claim 4 or 5, characterized in that: The catalyst is at least one of platinum-1,3-divinyltetramethyldisiloxane complex, bis(1,3-divinyl-1,1,3,3-tetramethyldisiloxane) platinum, platinum-1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane complex, and chloroplatinic acid vinyl complex methyl phthalate solution, and the platinum content is 1000-5000ppm.

7. The method for preparing a one-component addition type heat-curing liquid silicone rubber tackifier according to claim 6, characterized in that: The temperature of the heating reaction in step (1) is 60-100° C., and the reaction time is 2-4 hours.

8. The method for preparing a one-component addition type heat-curing liquid silicone rubber tackifier according to claim 6, characterized in that: The temperature of the heating reaction in step (1) is 60-70° C., and the reaction time is 2-4 hours.

9. A one-component addition type thermosetting liquid silicone rubber tackifier prepared by the preparation method according to any one of claims 2 to 8.

10. The use of the tackifier according to claim 9, characterized in that: It is used as a tackifier in one-component addition-type heat-curing liquid silicone rubber.

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