A compression set control agent, its preparation and use

Abstract

The application discloses a compression permanent deformation control agent and a preparation method and application thereof, and has the molecular structure shown in the following formula: wherein R1 and R2 are respectively selected from one of C1-C3 alkyl. The compression permanent deformation control agent provided by the application is a short-chain structure, has a small weight average molecular weight and low viscosity, contains a benzene ring, an amino group, a vinyl group and an alkoxy structure in the molecule, and after the compression permanent deformation control agent is used for modifying fumed silica, the amino group has strong polarity and is more easily attached to the surface of the fumed silica; the compression permanent deformation control agent and the modified fumed silica are used to prepare a silicone sealant material, the compression permanent deformation performance of the silicone sealant material is obviously improved, the compression permanent deformation of the silicone sealant material is low, the tensile strength is as high as 6.0 MPa or above, no filler settlement, hardening and other phenomena occur in the storage period, and the stability and reliability of the silicone sealant material in the long-term use process are obviously improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of organic silicon materials, and particularly relates to a compression permanent deformation control agent and a preparation method and application thereof. BACKGROUND

[0002] In recent years, new energy vehicles have been widely popularized and applied, and the key components include three systems of motors, electric controls and batteries. Among them, the electric control system is responsible for the energy distribution and power control of the new energy vehicle. In order to protect the internal components and electronic devices of the electric control system from being damaged by environmental factors during long-term use, the sealing performance of the electric control system is required to be very high. If the sealing is poor, the internal components of the electric control system will be corroded by dust, moisture, mold and the like, which may cause damage, short circuit and even accidents of the vehicle during driving.

[0003] Due to the good waterproofness, dustproofness, heat resistance, weather resistance, plasticity, adhesion and the like, the organic silicon sealant can be fully combined with the surface of the shell to ensure the sealing effect, and is widely used in the electric control system of the new energy vehicle. The common organic silicon sealant on the market has the defects of low extrusion rate, large compression permanent deformation and residual glue on the shell after aging. In particular, the compression permanent deformation of the sealing material relates to the stability and reliability of the electric control system during long-term use. Chinese Invention Patent No. CN112852167A discloses a low-hardness transparent liquid silicone rubber composition with low compression deformation, which improves the compression deformation performance by adding side vinyl silicone oil and vinyl MQ silicone resin. However, it is A and B two-component, which needs to be mixed before use, and is troublesome to use, and has been gradually eliminated by the market. Chinese Invention Patent No. CN115386333 discloses a low compression permanent deformation one-component heat-curable organic silicon sealant, which improves the strength and reduces the compression permanent deformation by adding vinyl MQ silicone resin containing benzene ring or epoxy. However, after introducing the benzene unit, the viscosity of the sealant increases obviously, and the adhesion is seriously lost, which cannot meet the more stringent requirements. SUMMARY

[0004] To solve the technical problems in the prior art, the purpose of the present application is to provide a compression permanent deformation control agent and a preparation method and application thereof. The low compression permanent deformation organic silicon sealant made of the compression permanent deformation control agent can significantly improve the compression permanent deformation performance of the organic silicon sealant and improve the stability and reliability thereof during long-term use.

[0005] To achieve the above purposes and achieve the above technical effects, the technical solution adopted by the present application is as follows:

[0006] The present application discloses a compression permanent deformation control agent, which has the following molecular structure:

[0007]

[0008] wherein R1 and R2 are independently selected from one of C1-C3 alkyl.

[0009] Further, the compression permanent deformation control agent has a weight average molecular weight of 300-500, a viscosity of 100-1000 cps, and a vinyl content of 20%-30%.

[0010] The application further discloses a preparation method of the compression permanent deformation control agent.

[0011] Step one: in a protective atmosphere, an intermediate product containing benzene ring and amino structure is prepared by Cl substitution reaction with gamma-chloropropyl trialkoxysilane and p-phenylenediamine as raw materials and under the action of a first catalyst, and the reaction equation is as follows:

[0012]

[0013] Step two: the compression permanent deformation control agent is prepared by condensation reaction with the intermediate product and vinyl trimethoxysilane as raw materials and under the action of a second catalyst, and the reaction equation is as follows:

[0014]

[0015] Further, in step one, the molar ratio of the gamma-chloropropyl trialkoxysilane and the p-phenylenediamine is 1:0.8-1.5; the temperature of the Cl substitution reaction is 80-120 DEG C, and the time is 1-5 h; the first catalyst is at least one of an organic tin catalyst, a titanate catalyst and an acid catalyst, and the acid catalyst is dilute hydrochloric acid and / or dilute sulfuric acid.

[0016] Further, in step two, the molar ratio of the intermediate product and the vinyl trimethoxysilane is 1:0.8-2; the temperature of the condensation reaction is 60-80 DEG C, and the time is 2-6 h; and the second catalyst is at least one of a Lewis acid and a Lewis base.

[0017] The application further discloses application of the compression permanent deformation control agent in preparation of surface modified fumed silica.

[0018] The application further discloses a preparation method of the surface modified fumed silica.

[0019] The compression permanent deformation control agent is dissolved in a solvent, heated to 50-70 DEG C, preheated for 20-40 min, then the fumed silica is added, heated to 70-90 DEG C, reacted for 100-150 min, cooled, dried, and the required surface modified fumed silica is prepared.

[0020] Further, after adding the fumed silica, stirring is carried out at a stirring rate of 50-100 r / min, the drying temperature is 110-130 DEG C, and the drying time is 50-70 min.

[0021] The application further discloses an application of the compression permanent deformation control agent in preparation of the low compression permanent deformation silicone sealant.

[0022] The application further discloses a low compression permanent deformation silicone sealant, which comprises the following components in parts by weight:

[0023] vinyl silicone oil 100 parts

[0024] vinyl silicone resin 10-30 parts

[0025] hydrogen-containing silicone oil 5-15 parts

[0026] surface-modified fumed silica 20-50 parts

[0027] flame-retardant filler 20-35 parts

[0028] adhesion promoter 1-3 parts

[0029] compression permanent deformation control agent 1-3 parts

[0030] catalyst 0.05-0.15 parts

[0031] inhibitor 0.1-0.5 parts

[0032] benzyl silicone oil 1-5 parts.

[0033] Compared with the prior art, the application has the following beneficial effects:

[0034] The application discloses a compression permanent deformation control agent and a preparation method and application thereof. The compression permanent deformation control agent has a short chain structure, a small weight average molecular weight and low viscosity, and contains benzene ring, amino group, vinyl group and alkoxy structure in the molecule. After the compression permanent deformation control agent is used to modify fumed silica, the amino group has strong polarity and is more easily attached to the surface of the fumed silica. The compression permanent deformation control agent and the modified fumed silica are used to cooperatively prepare a silicone sealant material, so that the compression permanent deformation performance of the silicone sealant material is obviously improved, the compression permanent deformation of the silicone sealant material is low, the tensile strength can be as high as 6.0 MPa or above, no filler settlement, hardening and other phenomena occur in the storage period, the storage stability is good, the aging stability is excellent, the stability and reliability of the silicone sealant material in the long-term use process are obviously improved, the probability of safety accidents of a motor system is reduced, raw materials are easy to obtain, preparation is simple, the reaction process is stable, and industrialized production is easy to realize. DETAILED DESCRIPTION

[0035] The present application will be described in detail below so that the advantages and features of the present application can be more easily understood by those skilled in the art, and the scope of protection of the present application can be more clearly defined.

[0036] The following presents a simplified summary of one or more aspects in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated aspects, and is intended to neither identify key or critical elements of all aspects nor delineate the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that is presented later.

[0037] In one aspect, the present application discloses a compression set control agent with a weight average molecular weight of 300-500, preferably 370-450, a vinyl content of 20%-30%, and a viscosity of 100-1000 cps, preferably 350-750 cps, and more preferably 500-700 cps. The compression set control agent provided by the present application has a molecular structure as shown below:

[0038]

[0039] wherein R1 and R2 are each selected from one of C1-C3 alkyl.

[0040] In another aspect, the present application also discloses a preparation method of the compression set control agent, comprising the following steps:

[0041] Step one: in a protective atmosphere, using γ-chloropropyl trialkoxysilane (γ-chloropropyl trimethoxysilane or γ-chloropropyl triethoxysilane) and p-phenylenediamine as raw materials, an intermediate product containing benzene ring and amino structure is prepared by Cl substitution reaction under the action of a first catalyst, and the reaction equation is as follows:

[0042]

[0043] Step two: using the intermediate product and vinyl trimethoxysilane as raw materials, the compression set control agent required to be synthesized is prepared by condensation reaction under the action of a second catalyst, and the reaction equation is as follows:

[0044]

[0045] In step one, the protective atmosphere is nitrogen, and the molar ratio of γ-chloropropyl trialkoxysilane to p-phenylenediamine is 1:0.8-1.5, preferably 1:1-1.5.

[0046] In step one, the temperature of the Cl substitution reaction is 80-120°C, and the time is 1-5h.

[0047] In step one, the first catalyst is at least one of an organotin catalyst, a titanate catalyst, and an acid catalyst.

[0048] In step one, the gamma-chloropropyl trialkoxysilane, the p-phenylenediamine, the first catalyst, and the solvent are mixed first, and then the Cl substitution reaction is carried out to obtain the desired intermediate product.

[0049] In step two, the molar ratio of the intermediate product to the vinyltrimethoxysilane is 1:0.8-2.

[0050] In step two, the temperature of the condensation reaction is 60-80 DEG C, and the time is 2-6 h.

[0051] In step two, the second catalyst is at least one of a Lewis acid and a Lewis base.

[0052] In step two, the intermediate product, the second catalyst, and the solvent are mixed first, and then the vinyltrimethoxysilane is gradually added dropwise to prepare the desired compression permanent deformation control agent through a condensation reaction.

[0053] The solvent is at least one of toluene, xylene, methyl ethyl ketone, and ethyl acetate.

[0054] The compression permanent deformation control agent provided by the application has a short chain structure, a small weight average molecular weight, and a low viscosity, and contains benzene rings, amino groups, vinyl groups, and alkoxy groups in the molecule, the amino groups have strong polarity, the vinyl groups are more easily exposed in the short chain structure, and thus the reaction activity is improved, the compression permanent deformation control agent can be crosslinked with hydrogen-containing silicone oil, and a more compact tri-connected network structure is more easily formed, the compression permanent deformation control agent is used to prepare a silicone sealant, the compression permanent deformation performance of the silicone sealant is obviously improved, and the stability and reliability of the silicone sealant during long-term use are improved.

[0055] The application further discloses an application of the compression permanent deformation control agent in preparation of surface-modified fumed silica.

[0056] A surface-modified fumed silica is prepared by surface modification of fumed silica with a specific surface area of 100-400 m 2 / g (preferably 200-400 m 2 / g), and the vinyl groups can be introduced on the surface of the fumed silica.

[0057] 1-3 parts of compression permanent deformation control agent is dissolved in 100 parts of solvent, heated to 50-70 DEG C, preheated for 20-40 min, then 20-50 parts of fumed silica is added, stirring, stirring rate is 50-100 r / min, heated to 70-90 DEG C, reaction 100-150 min, cooling, drying, drying temperature is 110-130 DEG C, drying time is 50-70 min, the desired surface modified fumed silica is prepared, the reaction equation is as follows:

[0058]

[0059] Wherein, R3 is

[0060] The application uses compression permanent deformation control agent as modifier to modify fumed silica, the surface modified fumed silica prepared has high compatibility, and further used for preparing silicone sealant material, which helps to improve the mechanical strength of the silicone sealant material.

[0061] Alkoxyl can form a connection between interfaces, effectively improve the compatibility between fumed silica and vinyl silicone oil, and fumed silica can be uniformly dispersed, so that the viscosity of the silicone sealant material is reduced, the surface of the modified fumed silica has vinyl-CH=CH2, which can react with hydrogen-containing silicone oil in the curing process, and a compact network structure is more easily formed, and the mechanical strength of the colloid product is obviously improved.

[0062] The application also discloses an application of the compression permanent deformation control agent in preparation of low compression permanent deformation silicone sealant.

[0063] A low compression permanent deformation silicone sealant, according to weight parts, comprises the following components:

[0064] Vinyl silicone oil 100 parts

[0065] Vinyl silicone resin 10-30 parts

[0066] Hydrogen-containing silicone oil 5-15 parts

[0067] Surface modified fumed silica 20-50 parts

[0068] Flame-retardant filler 20-35 parts

[0069] Tackifier 1-3 parts

[0070] Compression permanent deformation control agent 1-3 parts

[0071] Catalyst 0.05-0.15 parts

[0072] Inhibitor 0.1-0.5 parts

[0073] benzyl silicone oil 1-5 parts.

[0074] The viscosity of the vinyl silicone oil is 10000-50000 cps.

[0075] The inhibitor is an alkyne alcohol and / or maleic anhydride diallyl ester.

[0076] The application also discloses an application of the low-compression-permanent-deformation organic silicone sealant in a motor system control box or an electrical appliance packaging field.

[0077] Example 1

[0078] A compression permanent deformation control agent has a molecular structure as shown in the following formula:

[0079]

[0080] In the formula, R1 and R2 are methyl.

[0081] A preparation method of a compression permanent deformation control agent comprises the following steps:

[0082] Step one: under a nitrogen atmosphere, 120 g of p-phenylenediamine is diluted with 1000 g of toluene solvent to obtain a p-phenylenediamine solution, and the solution is transferred into a four-necked flask; 200 g of γ-chloropropyltrimethoxysilane and a first catalyst of dilute hydrochloric acid are mixed, and then the mixture is quickly added into the four-necked flask (with a reflux device) under nitrogen protection; the temperature is first heated to 60 DEG C, and then to 100 DEG C after stirring for 1 h; liquid reflux is observed; the temperature is kept for 2 h, and then the temperature is reduced to room temperature; the solvent and by-product are removed by rotary evaporation to prepare the intermediate product.

[0083] Step two: 300 g of the intermediate product and 150 g of vinyltrimethoxysilane are dissolved in 1000 g of toluene; under the action of a second catalyst of Lewis acid, the temperature is heated to 70 DEG C and kept for 2 h; the temperature is reduced to room temperature; the solvent and by-product are removed by rotary evaporation to prepare the compression permanent deformation control agent.

[0084] In step one, rapid temperature rising leads to accelerated molecular motion of reactants; rapid temperature rising may cause the reaction to be too violent, which may cause danger; and in the case of rapid temperature rising, the generation rate of by-products is accelerated; therefore, in this embodiment, the temperature is first heated to 60 DEG C and then to 100 DEG C, so that the generation of by-products is reduced by slow temperature rising, and the product purity is improved.

[0085] A preparation method of surface-modified fumed silica comprises the following steps:

[0086] The compression permanent deformation control agent is dissolved in 100 parts of toluene solvent, heated to 60°C, preheated for 30 minutes, then 20 parts of dispersed fumed silica is added, stirred at a stirring rate of 100 r / min, heated to 80°C, reacted for 120 minutes, then cooled to room temperature, filtered off the solvent and alcohol products, and placed in an oven for drying, with a drying temperature of 110°C and a drying time of 50 minutes, to obtain the desired surface-modified fumed silica.

[0087] A low compression permanent deformation silicone sealant, comprising the following components by weight:

[0088] Vinyl silicone oil 100 parts

[0089] Vinyl silicone resin 10 parts

[0090] Hydrogen-containing silicone oil 15 parts

[0091] Surface-modified fumed silica 50 parts

[0092] Flame-retardant filler 35 parts

[0093] Tackifier 3 parts

[0094] Compression permanent deformation control agent 3 parts

[0095] Organotin catalyst 0.15 parts

[0096] Alkynol inhibitor 0.5 parts

[0097] Benzyl silicone oil 3 parts.

[0098] The viscosity of the vinyl silicone oil is 10000 cps.

[0099] A method for preparing a low compression permanent deformation silicone sealant, comprising the following steps:

[0100] The vinyl silicone oil 100 parts, vinyl silicone resin 10 parts, hydrogen-containing silicone oil 15 parts, surface-modified fumed silica 50 parts, aluminum hydroxide flame-retardant filler 35 parts, tackifier 3 parts, compression permanent deformation control agent 3 parts, organotin catalyst 0.15 parts, alkynol inhibitor 0.5 parts, and benzyl silicone oil 3 parts are mixed uniformly by a planetary stirred tank, to obtain the desired low compression permanent deformation silicone sealant.

[0101] Example 2

[0102] A compression permanent deformation control agent, having a molecular structure as shown below:

[0103]

[0104] Wherein, R1 is methyl, and R2 is ethyl.

[0105] A preparation method of a compression set control agent, comprising the following steps:

[0106] Step one: dilute 120 g of p-phenylenediamine with 1000 g of toluene solvent to obtain a p-phenylenediamine solution, and transfer the solution into a four-necked flask; mix 230 g of γ-chloropropyl triethoxysilane and a first catalyst, and then quickly add them into the four-necked flask (with a reflux device) under nitrogen protection; heat and warm up to 70℃, stir for 1 h, then warm up to 100℃, and observe liquid reflux; keep the temperature for 1 h, then cool down to room temperature, and spin to remove the solvent and by-product, thereby preparing the intermediate product;

[0107] Step two: dissolve 300 g of the intermediate product and 150 g of vinyl trimethoxysilane in 1000 g of toluene, and heat and warm up to 70℃ under the action of a second catalyst; keep the temperature and stir for 2 h, then cool down to room temperature, spin to remove the solvent and by-product, thereby preparing the compression set control agent.

[0108] A preparation method of a surface modified fumed silica, comprising the following steps:

[0109] Dissolve the compression set control agent in toluene solvent, warm up to 60℃, preheat for 30 min, then add the dispersed fumed silica, stir at a stirring rate of 100 r / min, warm up to 80℃, react for 120 min, then cool down to room temperature, filter out the solvent and alcohol product, and place in an oven for drying; the drying temperature is 110℃, and the drying time is 50 min, thereby preparing the required surface modified fumed silica.

[0110] The rest is the same as in Example 1.

[0111] Example 3

[0112] A compression set control agent, having a molecular structure as shown below:

[0113]

[0114] In the formula, R1 is a methyl group, and R2 is a propyl group.

[0115] A preparation method of a compression set control agent, comprising the following steps:

[0116] Step one: under nitrogen atmosphere, 120g p-phenylenediamine is diluted with 1000g toluene solvent to obtain a p-phenylenediamine solution, which is transferred into a four-necked flask; 270g γ-chloropropyltriethoxysilane and a first catalyst are mixed and quickly added into the four-necked flask (with a reflux device) under nitrogen protection, heated to 60°C, stirred for 2h, then heated to 110°C, liquid reflux is observed, and the temperature is kept for 1.5h, then cooled to room temperature, and the solvent and by-product are removed by rotary evaporation to obtain the intermediate product;

[0117] Step two: 300g of the intermediate product and 150g of vinyltrimethoxysilane are dissolved in 1000g of toluene, heated to 70°C under the action of a second catalyst, stirred for 2h, cooled to room temperature, and the solvent and by-product are removed by rotary evaporation to obtain the compression permanent set control agent.

[0118] A method for preparing a surface-modified fumed silica, comprising the following steps:

[0119] The compression permanent set control agent is dissolved in toluene solvent, heated to 60°C, preheated for 30min, then the dispersed fumed silica is added, stirred at a speed of 100r / min, heated to 80°C, reacted for 120min, then cooled to room temperature, the solvent and alcohol product are filtered out, and then dried in an oven at a temperature of 110°C for 50min to obtain the desired surface-modified fumed silica.

[0120] The rest is the same as in Example 1.

[0121] Example 4

[0122] A compression permanent set control agent has a molecular structure as shown below:

[0123]

[0124] Wherein, R1 and R2 are both ethyl groups.

[0125] A method for preparing a compression permanent set control agent, comprising the following steps:

[0126] Step one: under nitrogen atmosphere, 120g p-phenylenediamine is diluted with 1000g toluene solvent to obtain a p-phenylenediamine solution, which is transferred into a four-necked flask; 270g γ-chloropropyltriethoxysilane and a first catalyst are mixed and quickly added into the four-necked flask (with a reflux device) under nitrogen protection, heated to 60°C, stirred for 2h, then heated to 110°C, liquid reflux is observed, and the temperature is kept for 1.5h, then cooled to room temperature, and the solvent and by-product are removed by rotary evaporation to obtain the intermediate product;

[0127] Step two: 300 g of the intermediate product and 180 g of vinyl trimethoxysilane were dissolved in 1000 g of toluene, and heated to 70°C under the action of a second catalyst, and stirred for 2 h. After cooling to room temperature, the solvent and by-product were removed by rotary evaporation to prepare the compression permanent set control agent.

[0128] A method for preparing surface-modified fumed silica, comprising the following steps:

[0129] The compression permanent set control agent was dissolved in toluene solvent, heated to 60°C, preheated for 30 min, then the dispersed fumed silica was added, and stirred at a stirring rate of 100 r / min, heated to 80°C, reacted for 120 min, then cooled to room temperature, and after filtering out the solvent and alcohol product, dried in an oven at a drying temperature of 110°C for 50 min to prepare the required surface-modified fumed silica.

[0130] The rest is the same as in Example 1.

[0131] Comparative Example 1

[0132] The difference between this comparative example and Example 1 is that octamethylcyclotetrasiloxane is used instead of the compression permanent set control agent in this comparative example, and the octamethylcyclotetrasiloxane has the following molecular structure:

[0133]

[0134] The rest is the same as in Example 1.

[0135] The compression permanent set test method is according to GB / T 7759.1-2015, and the curing condition is 150°C for 30 min. The sample piece is made into a sample block with a diameter of 29 mm ± 0.1 mm and a thickness of 12.5 mm ± 0.1 mm, the thickness of the sample block is measured with a thickness gauge, and is recorded as h0; then the sample block is compressed by 25% of the height of the sample block through a compression mold, and is recorded as hs; finally, the mold with the sample block is placed in a 150°C oven, and after 72 h, the sample block is taken out and cooled at room temperature for 30 min, and then the height is tested, and is recorded as h1. The compression permanent set calculation formula is:

[0136] C = [(h0-h1) / (h0-hs)]·100%.

[0137] The tensile strength and elongation at break test method is according to ISO 37, and the curing condition is 150°C for 30 min. The sample requirements are:

[0138] ① The width is not less than 30 mm, the length is not less than 120 mm, and the thickness is 2.0 ± 0.2 mm. For non-standard samples, the thickness is not more than 3 mm;

[0139] 2. The number of samples shall not be less than 3, and 5 samples are recommended to reduce data error;

[0140] 3. The vulcanized test piece shall be kept at room temperature for at least 16 hours before testing. The testing procedure is as follows:

[0141] 1) The tensile speed is set to 500 mm / min;

[0142] 2) The test position is marked according to the requirements, and the breaking position of all samples shall be within the marked area during the test. If the breaking position is outside the marked area, the data shall be discarded and the test shall be re-performed;

[0143] 3) The thickness of the test sample shall be tested, and the average value of three points in the marked area shall be input into the testing equipment;

[0144] 4) The test data of each qualified sample shall be recorded, and the elongation at break and tensile strength shall be recorded.

[0145] The hardness test method is according to ISO 868, and the curing conditions are 150℃@30min. The requirements for the test piece are as follows:

[0146] 1) The thickness shall be at least 4mm, and the test sample can be composed of multiple layers of thinner layers to obtain the necessary thickness, but the superposition may not be able to completely contact the multiple layers of test samples, which may affect the test results;

[0147] 2) The circumference / length of the test sample shall be sufficient to allow measurement at least 9mm from any edge, and the surface of the test sample shall be flat in an area sufficient to allow the foot to contact the test sample at a point at least 6mm radius from the indenter point. Hardness determination cannot be performed on a circular, uneven or rough surface. The testing procedure is as follows:

[0148] 1) Place the test piece on a hard, level surface. Keep the hardness tester probe in a vertical position, and the indentation point is at least 9mm from any edge of the test sample;

[0149] 2) Press the foot on the test sample as soon as possible without shaking, and keep the foot parallel to the surface of the test sample. Apply sufficient pressure to firmly contact the foot with the test sample.

[0150] 3) Read the scale of the indicating device after 15±1s;

[0151] 4) Perform five hardness measurements on different positions of the test sample, with each test point being at least 6mm apart, and determine the average value.

[0152] Shear strength (AL / AL) test is prepared according to GB / T 7124-2008, curing condition 150℃@30min, the sample is prepared, the bonding area length is 12.5mm±0.25mm, the sample should be consistent with the cutting direction of the metal bonding piece; the adhesive layer thickness is 0.2mm, the overflowed adhesive should be treated in time during the bonding process, the sample is symmetrically clamped on the clamp, the distance from the sample to the nearest joint is 50±1mm, the tensile testing machine is tested at a constant test speed, and the maximum load of the sample shear failure is recorded as the failure load.

[0153] The test results are shown in Table 1.

[0154] Table 1

[0155] Test item Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Tensile strength 6.8 6.4 6.1 5.6 4.6 Elongation at break 410 435 452 478 325 Hardness 45 42 38 36 52 Shear strength 4.1 4.08 3.95 3.8 1.2 Compression set 16 23 25 28 38

[0156] As can be seen from Table 1:

[0157] The mechanical strength of Examples 1-4 is higher than that of Comparative Example 1, because the fumed silica treated with vinyltrimethoxysilane has a certain amount of vinyl on the surface, which crosslinks with the hydrogen-containing silicone oil during the reaction to form a more dense network structure, greatly improving the strength of the silicone sealant and improving the compression set capacity. Comparative Example 1 uses fumed silica modified with octamethylcyclotetrasiloxane, which has a certain amount of hydroxyl groups on the surface, and has poor combination with hydrogen-containing silicone oil, and cannot form the above-mentioned dense network structure. In addition, the adhesion effect is too strong, the extrudability is poor, and the compression set capacity is poor. It can also be seen that the reinforcing effect of fumed silica modified with compression set control agent is greatly improved during the modification of fumed silica. Short-chain compression set control agent is more obvious in improving the strength, and the strength gradually decreases with the increase of chain length.

[0158] The parts or structures not specifically described in the present application can be realized by using existing technology or existing products, which will not be described here.

[0159] The above description is only an embodiment of the present application, and does not limit the patent scope of the present application, and any equivalent structure or equivalent process transformation using the content of the present application specification, or direct or indirect application in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A compression set control agent, characterized in that, The compression set control agent has the following molecular structure: ； R1 and R2 are each selected from one of the C1-C3 alkyl groups.

2. The method for preparing a compression set control agent according to claim 1, characterized in that, Includes the following steps: Step 1: Under a protective atmosphere, using γ-chloropropyltrialkoxysilane and p-phenylenediamine as raw materials, an intermediate product containing a benzene ring and an amino structure is prepared via a Cl substitution reaction in the presence of a first catalyst. The reaction equation is as follows: ； Step 2: Using the intermediate product and vinyltrialkoxysilane as raw materials, the desired compression set control agent is prepared through a condensation reaction under the action of a second catalyst. The reaction equation is as follows: 。 3. The method for preparing a compression set control agent according to claim 2, characterized in that, In step one, the molar ratio of γ-chloropropyltrialkoxysilane to p-phenylenediamine is 1:0.8-1.5; the temperature of the Cl substitution reaction is 80-120℃ and the time is 1-5h; the first catalyst is at least one of organotin catalyst, titanate catalyst, and acid catalyst, wherein the acid catalyst is dilute hydrochloric acid and / or dilute sulfuric acid.

4. The method for preparing a compression set control agent according to claim 2, characterized in that, In step two, the molar ratio of the intermediate product to vinyltrialkoxysilane is 1:0.8-2; the condensation reaction temperature is 60-80℃ and the time is 2-6h; the second catalyst is at least one of Lewis acid and Lewis base.

5. The application of the compression set control agent according to claim 1 in the preparation of surface-modified fumed silica.

6. A method for preparing surface-modified fumed silica, characterized in that, Includes the following steps: The compression set control agent of claim 1 is dissolved in a solvent, heated to 50-70°C, preheated for 20-40 min, then fumed silica is added, the temperature is raised to 70-90°C, the reaction is carried out for 100-150 min, cooled, and dried to obtain the surface-modified fumed silica.

7. The method for preparing surface-modified fumed silica according to claim 6, characterized in that, After adding fumed silica, stir at a rate of 50-100 r / min, dry at 110-130℃, and dry for 50-70 min.

8. The application of the compression set control agent according to claim 1 in the preparation of low compression set silicone sealant.

9. A low-compression-permanent silicone sealant, characterized in that, Based on parts by weight, it includes the following components: 100 parts vinyl silicone oil 10-30 parts vinyl silicone resin 5-15 parts of hydrogen-containing silicone oil 20-50 parts of surface-modified fumed silica prepared by the method for preparing surface-modified fumed silica according to claim 6 or 7 20-35 parts of flame retardant filler 1-3 parts of thickener 1-3 parts of the compression set control agent as described in claim 1 Catalyst 0.05-0.15 parts Inhibitor 0.1-0.5 parts 1-5 parts of benzyl silicone oil.

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