Migration-resistant polysiloxane plasticizer and organosilicon sealant containing same

Abstract

The invention belongs to the technical field of sealants, and relates to a migration-resistant polysiloxane plasticizer and an organosilicon sealant containing the migration-resistant polysiloxane plasticizer. Wherein a, b and c are integers, 0 < = a < = 8, 0 < = b < = 8, 0 < = c < = 8, and a + b + c > 0; r1 and R2 are independently alkyl of C1-C6, and R3 is gamma-aminopropyl, gamma-(2, 3-epoxypropoxy) propyl or gamma-isocyanate propyl; the organosilicon sealant contains a filler modified by a functional polymer, and the functional polymer is obtained by copolymerization of a polyether macromonomer, an indolyl-containing alkenyl monomer and an alkenyl silane coupling agent. The plasticizer disclosed by the invention has the advantages of migration resistance, good compatibility and avoidance of excessive cross-linking, and the plasticizer and the modified filler are cooperatively used, so that the adhesive property of the organic silicon sealant is effectively improved while the advantages of the plasticizer and the modified filler are exerted. # imgabs0 #

Description

Technical Field

[0001] The invention belongs to the technical field of sealants, and particularly relates to a migration-resistant polysiloxane plasticizer and an organosilicon sealant containing the same. Background Art

[0002] Silicone sealants have obvious advantages in terms of insulation, heat resistance, weather resistance, and flexibility, and are therefore widely used in electronic appliances, new energy, 5G, automobiles and other fields. Plasticizers generally need to be added to silicone sealants to improve their rheological properties and enhance their flexibility. Currently, the plasticizers commonly used in silicone sealants are divided into silicone plasticizers and non-silicone plasticizers. Silicone plasticizers commonly use low-viscosity methyl silicone oil (viscosity of 10 to 5000 cps), and non-silicone plasticizers commonly use polyterephthalates, such as diisononyl phthalate. However, after the products are cross-linked and cured, the above-mentioned commonly used plasticizers easily migrate to the surface of the product and cause oil seepage, which leads to a decrease in the adhesion of the silicone sealant or even adhesion failure; in addition, oil seepage can also cause dust to accumulate on the surface of the product, affecting the appearance. Li Yibo et al. (China Building Waterproofing, 2022 No. 11: 25-29) used silane-modified polyether resin (MS, STP-E) as the base polymer, and reacted it with different types of plasticizers (DL-2000D, DINCH, Mesamoll, XM20, XM25), reinforcing fillers, water absorbents, coupling agents and catalysts to prepare modified silane sealants with low plasticizer migration; the bonding properties of the prepared sealant and the plasticizer migration resistance cannot be improved at the same time.

[0003] Therefore, it is necessary to develop a migration-resistant plasticizer suitable for silicone sealants, which has the characteristics of being difficult to migrate and can improve the bonding performance of the sealant. Summary of the Invention

[0004] In view of the problem that plasticizers used in silicone sealants in the prior art are prone to migration and oil leakage, which in turn leads to a decrease in the adhesion of the silicone sealant, the present invention provides a migration-resistant polysiloxane plasticizer. When used in silicone sealants, this plasticizer can effectively improve the rheological properties and flexibility of the silicone sealant, while having the characteristics of being difficult to migrate and will not migrate to the product surface to cause oil leakage, and can improve its bonding performance.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A migration-resistant polysiloxane plasticizer, the structural formula of which is shown in Formula I below:

[0007]

[0008] Wherein, a, b, and c are integers, 0≤a≤8, 0≤b≤8, 0≤c≤8, and a+b+c>0;

[0009] R1 and R2 are each independently a C1-C6 alkyl group, and R3 is a γ-aminopropyl group, a γ-(2,3-epoxypropoxy)propyl group, or a γ-isocyanatepropyl group.

[0010] Preferably, in Formula I, 0≤a≤4, 0≤b≤4, 0≤c≤4, and a+b+c>0.

[0011] Preferably, in Formula I, R1 and R2 are each independently a methyl group or an ethyl group, and R3 is a γ-(2,3-epoxypropoxy)propyl group.

[0012] In a preferred embodiment of the present invention, the structural formula of the migration-resistant polysiloxane plasticizer is as follows:

[0013]

[0014] In formula II, 0≤a≤4, 0≤b≤4, 0≤c≤4, and a+b+c>0.

[0015] The plasticizer of structural formula I in the present invention is a "cross"-shaped polydimethylsiloxane containing a single active group. On the one hand, one end of the "cross" structure contains an active group, which can participate in the cross-linking and curing reaction, thereby making the plasticizer of structural formula I "anchored" in the molecular chain of the silicone elastomer in the form of a chemical bond, effectively avoiding migration and thus solving the oil seepage problem; on the other hand, the plasticizer of structural formula I has a "cross"-shaped multi-branched chain structure and is a polysiloxane, which has good compatibility with the matrix and thus has a good plasticizing effect; in addition, since it only contains an active group at one end of the "cross" structure and the other three ends are non-single active groups, it can avoid excessive cross-linking and reducing the bonding strength. The value ranges of a, b, and c in structural formula I are very critical. If the values ​​are too large, the viscosity of the plasticizer is too high and it is difficult to mix evenly with the matrix. Therefore, the value ranges of a, b, and c need to be controlled within the above ranges.

[0016] The migration-resistant polysiloxane plasticizer of the present invention has a viscosity of 35 to 80 cps at 25°C.

[0017] In a second aspect, the present invention also provides a method for preparing the above-mentioned migration-resistant polysiloxane plasticizer, comprising the following steps: uniformly mixing trialkoxysilane containing active functional groups and methyl silicone oil, then dropwise adding an aqueous solution of an acidic catalyst, and heating to 80-90°C for reaction after the dropwise addition is completed; finally, heating and evacuating the mixture to remove low-boiling substances to obtain the migration-resistant polysiloxane plasticizer.

[0018] Furthermore, the molar ratio of the trialkoxysilane containing active functional groups, methyl silicone oil, and acidic catalyst is 1:(1.5-2.0):(0.03-0.07), preferably 1:(1.6-1.8):(0.04-0.06).

[0019] Furthermore, the trialkoxysilane containing an active functional group is at least one of γ-aminopropyltriethoxysilane (KH550), γ-aminopropyltrimethoxysilane (KH792), γ-(2,3-epoxypropoxy)propyltriethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane (KH560), and γ-isocyanatepropyltriethoxysilane (KBE-9007), preferably γ-(2,3-epoxypropoxy)propyltriethoxysilane and γ-(2,3-epoxypropoxy)propyltrimethoxysilane (KH560). The silane containing an active functional group here needs to contain three alkoxy groups to satisfy the "cross" structure of the plasticizer of structural formula I containing a single active group.

[0020] Furthermore, the viscosity of the methyl silicone oil at 25°C is 2 to 10 cps, preferably 5 to 8 cps. The viscosity of the methyl silicone oil is directly related to the molecular weight (or the number of links in the molecular chain). When the viscosity of the methyl silicone oil at 25°C is 2 to 10 cps, the corresponding number average molecular weight is approximately between 350 and 800 (the number of siloxy links in the molecular chain is between 3 and 9). The viscosity range of the methyl silicone oil is, on the one hand, to ensure that a, b, and c in Structural Formula I are within the above range; on the other hand, the links of the methyl silicone oil with a viscosity of 2 to 10 cps are easily broken, thereby easily reacting with trialkoxysilanes containing active functional groups. After the reaction is completed, the unreacted methyl silicone oil is relatively easy to remove from the system.

[0021] Furthermore, the acidic catalyst is at least one of trifluoromethanesulfonic acid, hydrochloric acid, sulfuric acid, dodecylbenzenesulfonic acid, and trifluoroacetic acid, preferably hydrochloric acid; the concentration of the aqueous solution of the acidic catalyst is 0.2 to 0.5 mol / L, the system temperature is controlled to be 40 to 50°C during dropwise addition, and the dropwise addition is controlled to be complete within 30 to 60 minutes. Under the action of the acidic catalyst, the trialkoxysilane containing active functional groups is hydrolyzed, and the silanol groups generated by the hydrolysis undergo a condensation reaction with the highly reactive methyl silicone oil. Since the acidic catalyst is slowly added dropwise to the system, self-condensation of the trialkoxysilane containing active functional groups after hydrolysis is avoided.

[0022] Furthermore, the reaction time is 4 to 8 hours; the conditions for heating and vacuuming are: heating to 150 to 160° C., and vacuuming at -0.1 MPa to -0.01 MPa for 1 to 2 hours.

[0023] In a third aspect, the present invention further provides an organosilicon sealant comprising 3 to 8 wt% of the migration-resistant polysiloxane plasticizer by dry weight of the organosilicon sealant, wherein the organosilicon sealant comprises the following raw materials in parts by weight:

[0024]

[0025] The modified filler is obtained by modifying the filler with a functional polymer, and the amount of the functional polymer is 5 to 8 wt% of the filler; the functional polymer is obtained by copolymerization of a polyether macromonomer, an indole-containing alkenyl monomer, and an alkenyl silane coupling agent in a molar ratio of 1:(0.2 to 0.4):(0.1 to 0.3).

[0026] Furthermore, the filler is at least one of white carbon black, calcium carbonate, and calcined kaolin, and has a particle size D50 of 1 to 5 μm. The modification conditions are as follows: the filler and the functional polymer are added to an organic solvent and stirred under reflux at 50 to 60° C. for 2 to 5 hours. During the modification, the alkoxy groups in the functional polymer react with the active groups on the surface of the calcium carbonate, thereby introducing the functional polymer to the surface of the calcium carbonate in the form of a chemical bond.

[0027] Furthermore, the organic solvent is at least one of toluene and xylene.

[0028] Furthermore, the polyether macromonomer is selected from at least one of ethylene glycol monovinyl polyethylene glycol ether, methyl allyl polyethylene glycol ether, and methyl allyl butyl polyethylene glycol ether, wherein the number average molecular weight of the polyethylene glycol segment is 200 to 600; the indole-containing alkenyl monomer is selected from at least one of 3-vinyl indole and 3-acrylylindole; and the alkenyl silane coupling agent is selected from at least one of γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, vinyltriethoxysilane, and vinyltrimethoxysilane.

[0029] Furthermore, the functional polymer is prepared by a preparation method comprising the following steps: dissolving a polyether macromonomer, an indole-containing alkenyl monomer, an alkenyl silane coupling agent, and an initiator in a non-protonic polar organic solvent, reacting at 60-80° C. for 3-6 hours, cooling to obtain a suspension, and then filtering and drying the suspension to obtain the functional polymer.

[0030] Furthermore, the initiator is at least one of azobisisobutyronitrile and benzoyl peroxide, and the amount of the initiator is 1-2% of the total mass of the monomer; the aprotic polar organic solvent is at least one of N,N-dimethylformamide (DMF) and N,N-dimethylacetamide (DMAC); and the drying is vacuum drying at 60-80° C. for 12-24 hours.

[0031] The inventors have found through research that the modified filler used in silicone sealant can work synergistically with the migration-resistant polysiloxane plasticizer of formula I to effectively improve the adhesion of the silicone sealant. The possible reason is that although the plasticizer of formula I has excellent anti-migration properties, good compatibility and the characteristics of avoiding excessive cross-linking, its "cross" multi-branched structure makes it more "fluffy" in space, and its effective volume is large. It cannot effectively insert and separate polymer chains like linear molecules, so the plasticization efficiency per unit mass will be low; at the same time, multi-branching usually leads to increased intermolecular entanglement, making the bulk viscosity of the plasticizer higher than that of linear silicone oil with the same molecular weight, which puts pressure on the uniform dispersion of the filler; and the present invention, by modifying the filler, the copolymer containing indole groups and polyether segments is modified. The indole group is introduced to the filler surface through chemical bonding. The rigid bicyclic structure of the indole group not only provides a "reinforcement" effect but also offers significant steric hindrance, which helps prevent filler aggregation. The long polyether side chains, coupled with their flexibility and segmental mobility, offer a "supplementary plasticizing" effect and also act as a steric hindrance, further preventing filler aggregation. Therefore, the synergistic use of a plasticizer with Formula I and a modified filler, allowing the use of 3-8 wt% of the dry weight of the silicone sealant, effectively unleashes its advantages and also enhances the adhesive properties of the silicone sealant.

[0032] Furthermore, the reactive linear polydimethylsiloxane is α,ω-dihydroxy polydimethylsiloxane, and its viscosity at 25° C. is 3500 to 300,000 cps, preferably 5000 to 150,000 cps.

[0033] Furthermore, the cross-linking agent is a hydroxylated siloxane resin containing an MDT unit and having a hydroxyl content of 0.5 to 1.0 wt%; the surfactant is at least one of polyoxyethylene ether and polyoxypropylene ether, for example, at least one of isomeric tridecyl alcohol polyoxyethylene ether-8, isomeric tridecyl alcohol polyoxyethylene ether-10, and isomeric tridecyl alcohol polyoxyethylene ether-12; the adhesion promoter is an aminosilane, for example, at least one of γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane; the catalyst is at least one of dibutyltin dilaurate, dioctyltin dilaurate, dibutyltin diacetate, dimethyltin dineodecanoate, and chelated organic tin; and the water is softened water or pure water.

[0034] The preparation method of the organosilicon sealant comprises the following steps:

[0035] 1) adding reactive linear polydimethylsiloxane, migration-resistant polysiloxane plasticizer, crosslinking agent, surfactant, and water into a mixer and stirring and emulsifying to obtain an emulsion;

[0036] 2) adding the modified filler, adhesion promoter, and catalyst to the emulsion, diluting with water, and stirring to obtain a mixture;

[0037] 3) The mixture is subjected to vacuum degassing treatment and sub-packaging to obtain the silicone sealant.

[0038] Furthermore, the stirring conditions in step 1) are: a speed of 300 to 500 r / min, and a time of 20 to 40 minutes; the stirring conditions in step 2) are: a speed of 200 to 400 r / min, and a time of 50 to 90 min; and the conditions for the vacuum degassing treatment in step 3) are: a vacuum degree of less than 150 mbar, a speed of 100 to 200 r / min, and a time of 10 to 20 min.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] 1. The present invention adopts a trialkoxysilane containing an active functional group and a methyl silicone oil of a specific viscosity to form a "cross"-shaped polydimethylsiloxane containing a single active group through a hydrolysis condensation reaction, that is, a migration-resistant polysiloxane plasticizer. When used in a silicone sealant, due to its active group, it can participate in the cross-linking and curing reaction, thereby being "anchored" to the molecular chain of the silicone elastomer in the form of a chemical bond, effectively avoiding migration and thus solving the oil leakage problem; at the same time, due to its "cross"-shaped multi-branched chain structure and being a polysiloxane, it has good compatibility with the matrix and thus has a good plasticizing effect; in addition, since it contains an active group only at one end of the "cross" structure and the other three ends are non-single active groups, it can avoid excessive cross-linking and the reduction of bonding strength.

[0041] 2. The organic silicone sealant prepared by using the migration-resistant polysiloxane of the present invention as a plasticizer has the advantages of good bonding performance and no oil leakage.

[0042] 3. The present invention obtains a functional copolymer by copolymerizing a polyether macromonomer, an indole-containing alkenyl monomer, and an alkenyl silane coupling agent, and then modifies the filler by the functional copolymer to obtain a modified filler. The modified filler works synergistically with the migration-resistant polysiloxane of the present invention as a plasticizer, exerting the advantages of the plasticizer while effectively improving the bonding properties of the silicone sealant. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is the infrared spectrum of the migration-resistant polysiloxane plasticizer prepared in Example 1.

[0044] Figure 2 This is the infrared spectrum of the migration-resistant polysiloxane plasticizer prepared in Example 2.

[0045] Figure 3This is a diagram showing the damage to the adhesive layer during the adhesion performance test of silicone sealant.

[0046] Figure 4 This is a diagram showing the oil seepage phenomenon of the silicone sealant prepared in comparative application example 3. DETAILED DESCRIPTION

[0047] The present invention will be further described below with reference to specific examples, but the present invention is not limited to the following examples.

[0048] The experimental methods described in the following examples are conventional methods unless otherwise specified; the reagents and materials are commercially available unless otherwise specified.

[0049] Ethylene glycol monovinyl polyethylene glycol ether (EPEG-400) is selected from Aladdin, wherein the number average molecular weight of the polyethylene glycol segment is 400.

[0050] Methyl silicone oil is produced by Jiangxi Bluestar Star Fire Silicone Co., Ltd.

[0051] Reactive linear polydimethylsiloxane:

[0052]

[0053] The crosslinking agent hydroxylated siloxane resin has a hydroxyl content of about 0.5 wt %, and is selected from Jiangxi Lanxing Xinghuo Silicone Co., Ltd.

[0054] The aqueous solution of aminosilane, model Silquest VS142, solid content 25%, was selected from Sasol (China) Chemical Co., Ltd.

[0055] Calcium carbonate was selected from Jiangxi Hengshengtai New Materials Co., Ltd., model CC-800, particle size D50 = 3 μm.

[0056] Example 1

[0057] A migration-resistant polysiloxane plasticizer, the structural formula of which is as follows:

[0058]

[0059] The preparation method is:

[0060] 236.3 g (1 mol) of γ-(2,3-epoxypropoxy)propyltrimethoxysilane (KH560) and 808.5 g (1.75 mol) of methyl silicone oil with a viscosity of 5 cps at 25°C (whose number average molecular weight is 462.5 g / mol, and the corresponding chain number n is about 5) are added to a 2L IKA reactor and stirred at room temperature at 50 rpm for 30 minutes. 100 ml of 0.5 mol / L HCl aqueous solution is added dropwise to the reactor, and the addition is completed within 50 minutes. The system temperature is controlled at 45°C during the addition process. After the addition is completed, the reactor is heated to 85°C and reacted at 100 rpm for 6 hours. After the reaction is completed, the temperature is raised to 155°C and vacuumed (-0.09 MPa) for 1.5 hours to obtain a transparent viscous liquid, i.e., a migration-resistant polysiloxane plasticizer.

[0061] The reaction formula is as follows:

[0062]

[0063] According to the chain number n of methyl silicone oil being about 5, combined with the reaction principle, it can be inferred that in the structural formula, 0≤a≤4, 0≤b≤4, 0≤c≤4, and a, b, and c are not zero at the same time, that is, a+b+c>0.

[0064] The viscosity of the migration-resistant polysiloxane plasticizer obtained was 57 cps at 25° C. as measured by a rotational viscometer.

[0065] The infrared spectrum of the migration-resistant polysiloxane plasticizer prepared is as follows: Figure 1 As shown in the figure, 2942.34cm -1 and 2840.60cm -1 The peak of CH stretching vibration is attributed to methyl group; 1191.70 cm -1 and 1259.95cm -1 Si-C deformation vibration absorption peak; 1076.48 cm -1 is the Si-O-Si symmetric stretching vibration peak; 909.32cm -1 and 814.52cm -1 It is the characteristic absorption peak of epoxy.

[0066] Example 2

[0067] A migration-resistant polysiloxane plasticizer, the structural formula of which is as follows:

[0068]

[0069] The preparation method is:

[0070] 221.4 g (1 mol) of γ-aminopropyltriethoxysilane (KH550) and 558.1 g (1.75 mol) of methyl silicone oil with a viscosity of 2 cps at 25°C (whose number average molecular weight is 318.9 g / mol, corresponding to the number of chain segments n of approximately 3) were added to a 2L IKA reactor and stirred at room temperature at 50 rpm for 30 min. 100 ml of a 0.5 mol / L HCl aqueous solution was added dropwise to the reactor and the addition was completed within 50 min. During the addition, the system temperature was controlled at 45°C. After the addition was completed, the reactor was heated to 90°C and reacted at 100 rpm for 5 h. After the reaction was completed, the temperature was raised to 155°C and vacuumed (-0.09 MPa) for 1.5 hours to obtain a transparent viscous liquid, i.e., a migration-resistant polysiloxane plasticizer.

[0071] The reaction formula is as follows:

[0072]

[0073] According to the chain number n of methyl silicone oil being about 3, combined with the reaction principle, it can be inferred that in the structural formula, 0≤a≤2, 0≤b≤2, 0≤c≤2, and a, b, and c are not zero at the same time, that is, a+b+c>0.

[0074] The viscosity of the migration-resistant polysiloxane plasticizer obtained was 39 cps at 25° C. as measured by a rotational viscometer.

[0075] The infrared spectrum of the migration-resistant polysiloxane plasticizer prepared is as follows: Figure 2 As shown. 3675.63cm -1 -NH2 stretching vibration peak; 2967.22cm -1 and 2926.74cm -1 The peak of CH stretching vibration is attributed to methyl group; 1602.85cm -1 -NH2 bending vibration peak; 1295.81cm -1 is the absorption peak of Si-CH3; 1074.49 cm -1 and 1020.41cm -1 is the Si-O-Si stretching vibration peak, 955.04 cm -1 and 792.76cm -1 It is the characteristic absorption peak of Si-C.

[0076] Example 3

[0077] The rest is the same as Example 1, except that the viscosity of the methyl silicone oil at 25° C. is 2 cps (its number average molecular weight is 318.9 g / mol), and the specific preparation method is as follows:

[0078] 236.3 g (1 mol) of γ-(2,3-epoxypropoxy)propyltrimethoxysilane (KH560) and 558.1 g (1.75 mol) of methyl silicone oil with a viscosity of 2 cps at 25°C were added to a 2L IKA reactor and stirred at 50 rpm at room temperature for 30 min. 100 ml of a 0.5 mol / L HCl aqueous solution was added dropwise to the reactor over a period of 50 min. The system temperature was controlled at 45°C during the addition. After the addition was completed, the reactor was heated to 85°C and reacted at 100 rpm for 5 h. After the reaction was completed, the temperature was raised to 150°C and vacuumed (-0.09 MPa) for 1.5 h to obtain a transparent viscous liquid, i.e., a migration-resistant polysiloxane plasticizer.

[0079] The viscosity of the migration-resistant polysiloxane plasticizer obtained was 42 cps at 25° C. as measured by a rotational viscometer.

[0080] Example 4

[0081] The rest is the same as Example 1, except that the viscosity of the methyl silicone oil at 25° C. is 10 cps (its number average molecular weight is 785.5 g / mol, and the corresponding number of chain segments n is about 9). The specific preparation method is as follows:

[0082] 236.3 g (1 mol) of γ-(2,3-epoxypropoxy)propyltrimethoxysilane (KH560) and 1374.6 g (1.75 mol) of methyl silicone oil with a viscosity of 10 cps at 25°C were added to a 2L IKA reactor and stirred at 50 rpm at room temperature for 30 min. 100 ml of a 0.5 mol / L HCl aqueous solution was added dropwise to the reactor and the addition was completed within 50 min. The system temperature was controlled at 45°C during the addition. After the addition was completed, the reactor was heated to 90°C and reacted at 100 rpm for 6 h. After the reaction was completed, the temperature was raised to 160°C and vacuumed (-0.09 MPa) for 2 h to obtain a transparent viscous liquid, i.e., a migration-resistant polysiloxane plasticizer.

[0083] According to the chain number n of methyl silicone oil, which is about 9, combined with the reaction principle, it can be inferred that in the structural formula, 0≤a≤8, 0≤b≤8, 0≤c≤8, and a, b, and c are not zero at the same time, that is, a+b+c>0.

[0084] The viscosity of the migration-resistant polysiloxane plasticizer obtained was 73 cps at 25° C. as measured by a rotational viscometer.

[0085] Example 5

[0086] The rest is the same as Example 1, except that the methyl silicone oil is a mixture of methyl silicone oil with a viscosity of 2 cps at 25°C and methyl silicone oil with a viscosity of 10 cps at 25°C in an equal molar ratio (the viscosity of the mixture at 25°C is 8 cps). The specific preparation method is as follows:

[0087] 236.3 g (1 mol) of γ-(2,3-epoxypropoxy)propyltrimethoxysilane (KH560), 271.1 g (0.85 mol) of methyl silicone oil with a viscosity of 2 cps at 25°C, and 667.7 g (0.85 mol) of methyl silicone oil with a viscosity of 10 cps at 25°C (whose number average molecular weight is 785.49 g / mol) were added to a 2L IKA reactor and stirred at room temperature at 50 rpm for 30 min. 100 ml of 0.5 mol / L HCl aqueous solution was added dropwise to the reactor and the addition was completed within 50 min. The system temperature was controlled at 45°C during the addition process. After the addition was completed, the reactor was heated to 90°C and reacted at 100 rpm for 6 h. After the reaction was completed, the temperature was raised to 160°C and vacuumed (-0.09 MPa) for 2 h to obtain a transparent viscous liquid, i.e., a migration-resistant polysiloxane plasticizer.

[0088] The viscosity of the migration-resistant polysiloxane plasticizer obtained was 59 cps at 25° C. as measured by a rotational viscometer.

[0089] Comparative Example 1

[0090] The rest is the same as Example 1, except that γ-(2,3-epoxypropoxy)propylmethyldimethoxysilane is used in an equal molar amount to replace γ-(2,3-epoxypropoxy)propyltrimethoxysilane.

[0091] Comparative Example 2

[0092] The rest is the same as Example 1, except that the viscosity of the methyl silicone oil at 25° C. is 18 cps (its number average molecular weight is 1152.6 g / mol, and the corresponding number of chain segments n is approximately 15).

[0093] 236.3 g (1 mol) of γ-(2,3-epoxypropoxy)propyltrimethoxysilane (KH560) and 2017.1 g (1.75 mol) of methyl silicone oil with a viscosity of 18 cps at 25°C were added to a 3 L IKA reactor and stirred at 50 rpm at room temperature for 30 min. 100 ml of a 0.5 mol / L HCl aqueous solution was added dropwise to the reactor and the addition was completed within 50 min. The system temperature was controlled at 45°C during the addition. After the addition was completed, the reactor was heated to 90°C and reacted at 100 rpm for 6 h. After the reaction was completed, the temperature was raised to 160°C and vacuumed (-0.09 MPa) for 2 h to obtain a transparent viscous liquid, i.e., a migration-resistant polysiloxane plasticizer.

[0094] The viscosity of the migration-resistant polysiloxane plasticizer obtained was 102 cps at 25° C. as measured by a rotational viscometer.

[0095] Application Example 1

[0096] First prepare modified calcium carbonate

[0097] 1) preparing a mixture of ethylene glycol monovinyl polyethylene glycol ether (EPEG-400), 3-acryloylindole, and γ-methacryloyloxypropyltrimethoxysilane (KH550) in a molar ratio of 1:0.4:0.3 to a total mass of 100 g, then dissolving the mixture and 2 g of initiator benzoyl peroxide (BPO) in DMF; then reacting at 70° C. for 5 h, cooling to room temperature to obtain a suspension; filtering the suspension, vacuum drying at 60° C. for 24 h, and drying in an oven at 80° C. for 12 h to obtain a functional polymer;

[0098] 2) 100 parts of calcium carbonate and 5 parts of functional polymer were added to toluene, heated to 55°C and refluxed for 3 hours, cooled, filtered, and washed with pure water until the filtrate was colorless, and dried in an oven at 70°C for 24 hours to obtain modified calcium carbonate a.

[0099] Re-preparation of silicone sealant

[0100] An organosilicon sealant comprising the following raw materials in parts by weight:

[0101]

[0102] The organic silicon sealant was prepared by the following steps according to the above raw material dosages:

[0103] 1) adding α,ω-dihydroxy polydimethylsiloxane (model 47v135000), a migration-resistant polysiloxane plasticizer, a hydroxylated siloxane resin, isomeric tridecyl alcohol polyoxyethylene ether-8, and 7 parts of softened water to a double planetary mixer and stirring at 400 rpm for 30 minutes to obtain an emulsion with an average particle size D50 of 0.53 μm;

[0104] 2) Maintaining a rotation speed of 400 rpm, gradually add 30 parts of softened water to the emulsion over 15 minutes to obtain a diluted emulsion; then add Silquest VS142 (an aqueous solution of aminosilane) and modified calcium carbonate a, and continue stirring for 20 minutes; finally, add dioctyltin dilaurate, and continue stirring for 15 minutes to obtain a mixture;

[0105] 3) The mixture was degassed at a vacuum of 150 mbar at a rotation speed of 200 rpm for 15 minutes, and then the mixture was encapsulated into a rubber cylinder using a sealing machine to obtain a silicone sealant.

[0106] Application Example 2-5

[0107] The rest is the same as that of Application Example 1, except that the migration-resistant polysiloxane plasticizers are prepared according to Examples 2-5 respectively.

[0108] Application Example 6

[0109] The rest is the same as Application Example 1, except that the raw material composition ratio of the modified filler is different, and the raw material and composition ratio of the silicone sealant are different.

[0110] First prepare modified calcium carbonate

[0111] 1) A mixture of ethylene glycol monovinyl polyethylene glycol ether (EPEG-400), 3-acryloylindole, and γ-methacryloyloxypropyltrimethoxysilane (KH550) in a molar ratio of 1:0.2:0.1 was prepared to a total mass of 100 g, and the mixture and 2 g of initiator benzoyl peroxide (BPO) were dissolved in DMF; the mixture was then reacted at 70° C. for 5 h, and cooled to room temperature to obtain a suspension; the suspension was filtered, vacuum dried at 60° C. for 24 h, and then dried in an oven at 80° C. for 12 h to obtain a functional polymer.

[0112] 2) 100 parts of calcium carbonate and 8 parts of functional polymer were added to toluene, heated to 55°C and refluxed for 3 hours, cooled, filtered, washed with pure water until the filtrate was colorless, and dried in an oven at 70°C for 24 hours to obtain modified calcium carbonate b.

[0113] Re-preparation of silicone sealant

[0114] An organosilicon sealant comprising the following raw materials in parts by weight:

[0115]

[0116]

[0117] The organic silicon sealant was prepared by the following steps according to the above raw material dosages:

[0118] 1) adding α,ω-dihydroxy polydimethylsiloxane (model 47v5000), a migration-resistant polysiloxane plasticizer, a hydroxylated siloxane resin, isomeric tridecyl alcohol polyoxyethylene ether-8, and 7 parts of softened water to a double planetary mixer and stirring at 400 rpm for 30 minutes to obtain an emulsion with an average particle size D50 of 0.53 μm;

[0119] 2) Maintaining a rotation speed of 400 rpm, gradually add 30 parts of softened water to the emulsion over 15 minutes to obtain a diluted emulsion; then add Silquest VS142 (an aqueous solution of aminosilane) and modified calcium carbonate b, and continue stirring for 20 minutes; finally, add dioctyltin dilaurate, and continue stirring for 15 minutes to obtain a mixture;

[0120] 3) The mixture was degassed at a vacuum of 150 mbar at a rotation speed of 200 rpm for 15 minutes, and then the mixture was encapsulated into a rubber cylinder using a sealing machine to obtain a silicone sealant.

[0121] Comparative Application Examples 1-2

[0122] The rest is the same as Application Example 1, except that: when preparing the silicone sealant, the migration-resistant polysiloxane plasticizer is prepared as Comparative Examples 1-2 respectively.

[0123] Comparative Application Example 3

[0124] The rest is the same as that of Application Example 1, except that: when preparing the silicone sealant, methyl silicone oil with a viscosity of 100 cps at 25° C. is used instead of the migration-resistant polysiloxane plasticizer in Example 1, that is, a conventional plasticizer is used.

[0125] Comparative Application Example 4

[0126] The rest is the same as Application Example 1, except that calcium carbonate is used instead of modified calcium carbonate a, that is, the filler is not modified.

[0127] Testing and Analysis

[0128] The organic silicone sealants prepared in the above application examples and comparative application examples were subjected to the following performance tests, and the test results are shown in Table 1.

[0129] Adhesion performance test: According to "GBT13477.8-2017 Test methods for building sealing materials Part 8 Determination of tensile adhesion", prepare national standard parts of aluminum sheets and glass sheets, inject the silicone sealant prepared in the application example or comparative application example between the aluminum sheet and the glass bottle, and perform tensile adhesion test after curing for 28 days at 23℃±1℃ and relative humidity of 50%±2%. Observe the bonding surface of the aluminum sheet and the glass sheet. If there is residual adhesive layer on the bonding surface, it is cohesive failure; if there is no adhesive layer on the bonding surface, it is adhesive failure; the percentage of cohesive failure is defined as the percentage of the area of ​​the residual adhesive layer on the bonding surface. The larger the percentage of cohesive failure, the better the bonding performance. The damage of the adhesive layer during the adhesion performance test is shown in the figure below. Figure 3 As shown, the black part in the figure is silicone sealant. The adhesive joint in Figure a is damaged from the colloid itself, and the interface is entirely residual glue, that is, 100% cohesive failure; the adhesive joint in Figure b is separated from the bonding surface, and there is no glue residue at the interface, that is, all is adhesive failure, and the cohesive failure is 0%; in Figure c, part is adhesive failure and part is cohesive failure.

[0130] Oil seepage: The organic silicone sealants prepared in the application examples and comparative examples were squeezed onto PE films using a glue gun, and then scraped into films with a thickness of 2±0.2mm using a scraper. The films were cured at 23℃±1℃ and a relative humidity of 50%±2% for 14 days and 28 days, and the surface oil seepage of the films after curing was recorded by finger touch. The test results are shown in Table 1. The oil seepage of the organic silicone sealant prepared in comparative application example 2 is shown in Table 1. Figure 4 shown.

[0131] Table 1 Performance test of silicone sealant after curing

[0132]

[0133]

[0134] As can be seen from Table 1, the migration-resistant polysiloxane plasticizer of the present invention does not migrate to the product surface and cause oil seepage when used in silicone sealants, and the resulting silicone sealants have good interfacial bonding properties, with cohesive failure at the interfacial bonding sites exceeding 85%, and in preferred examples exceeding 95%. The plasticizer prepared in Comparative Example 1 does not migrate to the product surface and cause oil seepage when used in silicone sealants, but the resulting silicone sealants have poor interfacial bonding properties. Comparative Example 2, in which a plasticizer prepared using a relatively high-viscosity methyl silicone oil is used in silicone sealants, has poor interfacial bonding properties and slight oil seepage. This may be due to the high viscosity of the methyl silicone oil, which makes it difficult to react with the trialkoxysilane containing active functional groups, and the fact that unreacted methyl silicone oil is difficult to escape from the system due to its high viscosity. Furthermore, the high viscosity of the plasticizer makes it difficult to mix evenly with the matrix, thus affecting bonding strength. Comparing the conventional plasticizer used in Application Example 3, it can be seen that when used in silicone sealant, it not only migrates to the product surface and causes oil seepage, but also has poor bonding performance. The filler in Application Example 4 is unmodified, and the silicone sealant's bonding performance is worse than that of the application example.

[0135] The above contents are only preferred embodiments of the present invention and are not intended to limit the implementation scheme of the present invention. Ordinary technicians in this field can easily make corresponding changes or modifications based on the main concepts and spirit of the present invention. Therefore, the scope of protection of the present invention shall be based on the scope of protection required by the claims.

Claims

1. A migration-resistant polysiloxane plasticizer, characterized in that: Its structural formula is shown in the following formula I: Wherein, a, b, and c are integers, 0≤a≤8, 0≤b≤8, 0≤c≤8, and a+b+c>0; R1 and R2 are each independently a C1-C6 alkyl group, and R3 is a γ-aminopropyl group, a γ-(2,3-epoxypropyloxy)propyl group, or a γ-isocyanatepropyl group.

2. The migration-resistant polysiloxane plasticizer according to claim 1, characterized in that In formula I, 0≤a≤4, 0≤b≤4, 0≤c≤4, and a+b+c>0; R1 and R2 are each independently a methyl group or an ethyl group, and R3 is a γ-(2,3-epoxypropoxy)propyl group.

3. The method for preparing the migration-resistant polysiloxane plasticizer according to claim 1 or 2, characterized in that: The method comprises the following steps: uniformly mixing trialkoxysilane containing active functional groups and methyl silicone oil, then dripping an aqueous solution of an acidic catalyst, heating to 80-90° C. for reaction after the dripping is completed; and finally heating and vacuuming to remove low-boiling substances to obtain a migration-resistant polysiloxane plasticizer.

4. The preparation method according to claim 3, characterized in that The molar ratio of the trialkoxysilane containing active functional groups, methyl silicone oil and acidic catalyst is 1:(1.5-2.0):(0.03-0.07), preferably 1:(1.6-1.8):(0.04-0.06).

5. The preparation method according to claim 3, characterized in that The trialkoxysilane containing active functional groups is at least one of γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-(2,3-epoxypropoxy)propyltriethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, and γ-isocyanatepropyltriethoxysilane, preferably γ-(2,3-epoxypropoxy)propyltriethoxysilane and γ-(2,3-epoxypropoxy)propyltrimethoxysilane; and / or The viscosity of the methyl silicone oil at 25° C. is 2 to 10 cps, preferably 5 to 8 cps; and / or The acidic catalyst is at least one of trifluoromethanesulfonic acid, hydrochloric acid, sulfuric acid, dodecylbenzenesulfonic acid, and trifluoroacetic acid, preferably hydrochloric acid; the concentration of the aqueous solution of the acidic catalyst is 0.2 to 0.5 mol / L, the system temperature is controlled to be 40 to 50° C. during the dropwise addition, and the dropwise addition is completed within 30 to 60 minutes; and / or The reaction time is 4 to 8 hours; the conditions for heating and vacuuming are: heating to 150 to 160° C. and vacuuming at -0.1 MPa to -0.01 MPa for 1 to 2 hours.

6. An organic silicon sealant, characterized in that: The invention comprises 3 to 8 wt% of the migration-resistant polysiloxane plasticizer according to claim 1 or 2 by weight of the dry weight of the organic silicone sealant, wherein the organic silicone sealant comprises the following raw materials in parts by weight: The modified filler is obtained by modifying the filler with a functional polymer, and the amount of the functional polymer is 5 to 8 wt% of the filler; the functional polymer is obtained by copolymerization of a polyether macromonomer, an indole-containing alkenyl monomer, and an alkenyl silane coupling agent in a molar ratio of 1:(0.2 to 0.4):(0.1 to 0.3).

7. The organic silicon sealant according to claim 6, characterized in that: The filler is at least one of white carbon black, calcium carbonate, and calcined kaolin, and has a particle size D50 of 1 to 5 μm. The modification conditions are: adding the filler and the functional polymer to an organic solvent, stirring and refluxing at 50 to 60° C. for 2 to 5 hours.

8. The organic silicon sealant according to claim 6, characterized in that: The polyether macromonomer is selected from at least one of ethylene glycol monovinyl polyethylene glycol ether, methyl allyl polyethylene glycol ether, and methyl allyl butyl polyethylene glycol ether, wherein the number average molecular weight of the polyethylene glycol segment is 200 to 600; the indole-containing alkenyl monomer is selected from at least one of 3-vinyl indole and 3-acrylylindole; the alkenyl silane coupling agent is selected from at least one of γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, vinyltriethoxysilane, and vinyltrimethoxysilane; Preferably, the functional polymer is prepared by a preparation method comprising the following steps: dissolving a polyether macromonomer, an indole-containing alkenyl monomer, an alkenyl silane coupling agent, and an initiator in an aprotic polar organic solvent, reacting at 60-80° C. for 3-6 hours, cooling to obtain a suspension, and purifying to obtain the functional polymer; More preferably, the initiator is at least one of azobisisobutyronitrile and benzoyl peroxide, and the amount of the initiator is 1-2% of the total mass of the monomer; the aprotic polar organic solvent is at least one of N,N-dimethylformamide and N,N-dimethylacetamide; and the purification method is: filtering the suspension and vacuum drying at 60-80°C for 12-24 hours.

9. The organic silicon sealant according to claim 6, characterized in that: The reactive linear polydimethylsiloxane is α,ω-dihydroxypolydimethylsiloxane, and its viscosity at 25°C is 3500-300000cps, preferably 5000-150000cps; the crosslinking agent is a hydroxylated siloxane resin, and the hydroxyl content is 0.5-1.0wt%; the surfactant is at least one of polyoxyethylene ether and polyoxypropylene ether; the adhesion promoter is an aminosilane, for example, at least one of γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane; the catalyst is at least one of dibutyltin dilaurate, dioctyltin dilaurate, dibutyltin diacetate, dimethyltin dineodecanoate, and chelated organic tin; and the water is softened water or pure water.

10. The method for preparing the organosilicon sealant according to claim 6, characterized in that: The following steps are involved: 1) adding reactive linear polydimethylsiloxane, migration-resistant polysiloxane plasticizer, crosslinking agent, surfactant, and water into a mixer and stirring and emulsifying to obtain an emulsion; 2) adding the modified filler, adhesion promoter, and catalyst to the emulsion, diluting with water, and stirring to obtain a mixture; 3) The mixture is subjected to vacuum degassing treatment and sub-packaging to obtain the silicone sealant.

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