Composition for composite insulator silicone rubber, composite insulator silicone rubber and preparation method of composite insulator silicone rubber

Abstract

The invention relates to the technical field of composite insulator manufacturing, and discloses a composition for composite insulator silicone rubber, the composite insulator silicone rubber and a preparation method of the composite insulator silicone rubber. The composition contains a main agent and an auxiliary agent, the main agent contains an anti-ultraviolet system, silicone rubber, a reinforcing agent and a flame retardant; the anti-ultraviolet system comprises a benzotriazole ultraviolet absorbent and an inorganic filler. The mechanical performance and the electrical performance of the composite insulator silicone rubber provided by the invention are remarkably improved, the physical performance is slightly reduced after 1000 hours of ultraviolet accelerated aging, the service life is prolonged, the outdoor aging problem of the composite insulator silicone rubber can be effectively solved, and safe and stable operation of a power transmission line is ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of composite insulator manufacturing, and in particular to a composite insulator silicone rubber composition, a composite insulator silicone rubber and a preparation method thereof. BACKGROUND

[0002] The outdoor operation environment of a composite insulator is complex, and the composite insulator is exposed to the sun's ultraviolet radiation, heat and humidity, coastal salt spray, polluted dust and electric field (partial discharge / surface corona) for a long time, which may cause the following problems: photo-oxidation of the material surface, uneven chain scission and crosslinking, formation of surface microcracks and pores, decrease in hydrophobicity, gradual degradation of mechanical properties (tensile strength, tear strength, elongation at break) and electrical properties (tracking resistance, breakdown strength, surface resistivity), and ultimately lead to failure of the insulator, string breakage or an increase in flashover accidents.

[0003] At present, the commonly used anti-ultraviolet system includes inorganic fillers (such as nano / micron TiO2 and ZnO). In the composite insulator sheath, ZnO is widely used to improve the ultraviolet weather resistance because it can scatter / absorb short-wave ultraviolet light and enhance surface reflection, thereby weakening the direct damage of incident ultraviolet energy to the high molecular polymer matrix.

[0004] However, there are several defects in using only inorganic fillers as anti-ultraviolet fillers: (1) photocatalytic activity problem: some anti-ultraviolet fillers generate ·OH and other free radicals under ultraviolet excitation, which may accelerate the high molecular chain scission and oxidation; (2) dispersion and mechanical properties: nano anti-ultraviolet fillers still have a slight risk of agglomeration, and the agglomeration area has insufficient anti-ultraviolet ability, which is easy to become a local aging hotspot, resulting in uneven overall anti-aging performance; (3) filler precipitation problem: TiO2 may precipitate from the surface of the silicone rubber during the aging process, resulting in a decrease in ultraviolet absorption performance. SUMMARY

[0005] The purpose of the present application is to overcome the material aging and performance degradation problems of the existing composite insulator silicone rubber in outdoor operation due to ultraviolet radiation and other factors.

[0006] The inventors of the present application provide the present application based on the following inventive ideas: The introduction of benzotriazole organic ultraviolet absorber (particularly preferably UV-328) and inorganic filler (particularly preferably rutile nano-TiO2) in the silicone rubber sheath formula can provide complementary protection. The benzotriazole organic ultraviolet absorber can efficiently absorb UVA / UVB radiation through intramolecular conjugated structure and dissipate energy, and can be uniformly dispersed in the silicone rubber, can fill the gap formed by TiO2 agglomeration, avoid local insufficient ultraviolet resistance, and ensure performance uniformity. The synergistic effect of the two can achieve broad-spectrum protection, reduce the photocatalytic side effect, and improve long-term weather resistance.

[0007] Therefore, the first aspect of the present application provides a composite insulator silicone rubber composition, which contains a main agent and an auxiliary agent; the main agent contains an ultraviolet-resistant system, a silicone rubber, a reinforcing agent, and a flame retardant; the ultraviolet-resistant system includes a benzotriazole ultraviolet absorber and an inorganic filler; The content of the ultraviolet-resistant system is 6-11 wt%, the content of the silicone rubber is 40-42 wt%, the content of the reinforcing agent is 10-15 wt%, and the content of the flame retardant is 35-38 wt%, based on the total weight of the composition; In the ultraviolet-resistant system, the mass ratio of the benzotriazole ultraviolet absorber to the inorganic filler is 1:6-22.

[0008] The second aspect of the present application provides a method for preparing a composite insulator silicone rubber, which uses the components in the composition of the first aspect, including: (1) First mixing the silicone rubber, the benzotriazole ultraviolet absorber, the inorganic filler, the reinforcing agent, the flame retardant, and the structure control agent, the softening agent, and the coupling agent in the auxiliary agent to obtain a mixture I; (2) Kneading the mixture I to obtain a kneaded product; (3) Adding a vulcanizing agent to the kneaded product for vulcanization treatment to obtain the composite insulator silicone rubber.

[0009] The third aspect of the present application provides a composite insulator silicone rubber prepared by the method of the second aspect.

[0010] Through the above technical solution, the present application has at least the following advantages: The mechanical and electrical properties of the composite insulator silicone rubber provided by the present application are significantly improved, the physical property decline amplitude after 1000 h ultraviolet accelerated aging is significantly reduced, the service life is prolonged, and the safe and stable operation of the power transmission line is ensured. DETAILED DESCRIPTION

[0011] The endpoints of the ranges and any values disclosed herein are not limited to the precise values recited as the exact dimensions are not critical to the invention. Any numeric range recited is intended to include all values from the lower value to the upper value, inclusive of both values, and to also include any value approximately or about the same as that particular value. Numeric ranges are inclusive of the endpoints.

[0012] As described above, the first aspect of the present application provides a composite insulating silicone rubber composition, which comprises a main agent and an auxiliary agent; the main agent comprises an anti-ultraviolet system, a silicone rubber, a reinforcing agent, and a flame retardant; the anti-ultraviolet system comprises a benzotriazole ultraviolet absorber and an inorganic filler; The content of the anti-ultraviolet system is 6-11wt%, the content of the silicone rubber is 40-42wt%, the content of the reinforcing agent is 10-15wt%, and the content of the flame retardant is 35-38wt%, based on the total weight of the composition. In the anti-ultraviolet system, the mass ratio of the benzotriazole ultraviolet absorber to the inorganic filler is 1:6-22.

[0013] Preferably, the average particle size of the benzotriazole ultraviolet absorber is 5-20µm.

[0014] Preferably, the benzotriazole ultraviolet absorber is selected from at least one of UV-328 and UV-326.

[0015] Preferably, the weight average diameter of the inorganic filler is 30-50nm.

[0016] Preferably, the inorganic filler is selected from at least one of nano-TiO2 and nano-ZnO.

[0017] Further preferably, the inorganic filler is nano-TiO2 of rutile type.

[0018] Preferably, the silicone rubber is polydimethyl vinyl silicone rubber.

[0019] Further preferably, the molecular weight of the silicone rubber is 630-650 thousand, and the content of vinyl structural units is 0.1-0.2wt%.

[0020] Preferably, the maximum particle size of the reinforcing agent is 4-6µm, and the median particle size is 1-3µm. Preferably, the reinforcing agent is micron-sized fumed white carbon black.

[0021] Preferably, the maximum particle size of the flame retardant is 4-6µm, and the median particle size is 1-3µm.

[0022] Preferably, the flame retardant is micron-sized aluminum hydroxide.

[0023] Preferably, the auxiliary agent contains a structure control agent, a vulcanizing agent, a softening agent, and a coupling agent.

[0024] Preferably, the content of the structure control agent is 0.5-3wt%, the content of the vulcanizing agent is 0.15-0.18wt%, the content of the softening agent is 0.1-0.3wt%, and the content of the coupling agent is 0.8-0.9wt%, based on the total weight of the composition.

[0025] Further preferably, the structure control agent is selected from at least one of hydroxyl silicone oil, vinyl silicone oil, and diphenylsilanediol; the vulcanizing agent is selected from at least one of 1,1-bis(tert-butyl peroxy)-3,3,5-trimethylcyclohexane, dicumyl peroxide, and 2,5-dimethyl-2,5-bis(tert-butyl peroxy)hexane; the softening agent is selected from at least one of methyl silicone oil, ethyl silicone oil, and phenylmethyl silicone oil; and the coupling agent is selected from at least one of vinyltrimethoxysilane and vinyltri(β-methoxyethoxy)silane.

[0026] As described previously, the second aspect of the present application provides a method for preparing a composite insulator silicone rubber, which is performed using the components in the composition of the first aspect, and includes: (1) first mixing silicone rubber, a benzotriazole ultraviolet absorber, inorganic fillers, a reinforcing agent, a flame retardant, and a structure control agent, a softening agent, and a coupling agent in an auxiliary agent to obtain a mixture I; (2) performing a rubber mixing process on the mixture I to obtain a rubber mixing product; (3) adding a vulcanizing agent to the rubber mixing product to perform a vulcanization process to obtain the composite insulator silicone rubber.

[0027] According to a preferred embodiment, in step (1), the conditions of the first mixing include: a temperature ≤70℃, a time of 0.8-1.2h, and a stirring speed of 10-20rpm.

[0028] Preferably, in step (2), the rubber mixing process is performed on a two-roll open mill.

[0029] Preferably, the operating conditions of the two-roll open mill include: a roll gap of 18-22mm.

[0030] Further preferably, the rubber mixing process is repeated 5 times.

[0031] According to a particularly preferred embodiment, the rubber product is subjected to the mixing operation in a double-rotation swing drum mixer before the vulcanization treatment, and the mixing operation is performed under the following conditions: rotation speed alternation between 34 rpm and 28 rpm, single duration of each rotation speed being 10 min, mixing time being 1-2 h. The inventors have found that, in this preferred case, the inorganic filler agglomeration is effectively reduced, while ensuring a uniform dispersion of the benzotriazole UV absorber.

[0032] Further preferably, in step (3), the vulcanization treatment is performed under the following conditions: temperature being 120-160 °C, pressure being 8-12 MPa, time being 8-12 min.

[0033] Preferably, the vulcanization treatment is performed on a flat vulcanization machine.

[0034] As mentioned above, the third aspect of the present application provides a composite insulator silicone rubber prepared by the method of the second aspect.

[0035] Preferably, the composite insulator silicone rubber has a breakdown strength ≥ 24.9 kV / mm, a volume resistivity ≥ 8.2 x 10 13 Ω·m, a tear strength ≥ 16.7 kN / m, and a tensile strength ≥ 4.3 MPa.

[0036] Further preferably, the composite insulator silicone rubber has a surface resistivity ≥ 1.8 x 10 13 Ω, and an elongation at break ≥ 270%.

[0037] The present application will be described in detail below by way of examples. In the following examples, various instruments and raw materials (analytically pure) used are all commercially available unless otherwise specified.

[0038] Benzotriazole UV absorber: UV-328, average particle size being 20 µm, available from CIBA; UV-326, average particle size being 20 µm, available from CIBA; Inorganic filler: Rutile-type nano-TiO2, weight average diameter being 50 nm, available from Jixing Micro-nano New Material Technology Co., Ltd.; Nano-ZnO, weight average diameter being 50 nm, available from Jiupeng New Material Co., Ltd.; Silicone rubber: polydimethyl vinyl silicone rubber, molecular weight being 630-650 thousand, content of vinyl structural unit being 0.16 wt%, available from Hesheng Silicone Co., Ltd.; Reinforcing agent: micron-sized fumed white carbon black, purity of 99.8wt%, maximum particle size of 5μm, median particle size of 1.5μm, purchased from Hesheng Silicon Industry Co., Ltd.; Flame retardant: micron-sized aluminum hydroxide, maximum particle size of 5μm, median particle size of 1.5μm, purchased from Shandong Shilbang Chemical Technology Co., Ltd.; Structure control agent: hydroxyl silicone oil, purchased from Jiangsu Quanli Chemical Co., Ltd.; Vulcanizing agent: 1,1-bis(tert-butyl peroxy)-3,3,5-trimethylcyclohexane, abbreviated as TMCH, purchased from Shenzhen Tico Technology Co., Ltd.; Softener: methyl silicone oil, purchased from Dow Corning Corporation; Coupling agent: Vinyl trimethoxysilane, abbreviated as A171, purchased from Shenzhen Ruixi Rubber Technology Co., Ltd.; Vinyl tri(β-methoxyethoxy)silane, abbreviated as A172, purchased from Shenzhen Ruixi Rubber Technology Co., Ltd.

[0039] Example 1 (1) 10kg of benzotriazole ultraviolet absorber, inorganic filler, silicone rubber, reinforcing agent, flame retardant, structure control agent, softener and coupling agent were added to a mixer and mixed at a speed of 20rpm for 1h, with the temperature controlled at ≤70℃, to obtain a mixture I; (2) The mixture I obtained in step (1) was transferred to a two-roll open mill, and the roll gap was set to 20mm. The rubber was repeatedly milled 5 times to obtain a milled product; (3) The milled product obtained in step (2) was subjected to internal mixing in a double-speed oscillating drum, with the speed being alternately 34rpm and 28rpm, and the single duration of the two speeds being 10min. The internal mixing time was 2h.

[0040] (4) The vulcanizing agent was added to the milled product after internal mixing, and the vulcanization was carried out on a flat vulcanizing machine at 140℃ and 10MPa for 10min to obtain a composite insulator silicone rubber.

[0041] The remaining specific process parameters of this example are shown in Table 1.

[0042] Examples 2-5 Examples 2-5 all used the same process flow as Example 1, with the differences listed in Table 1.

[0043] Comparative Examples 1-2 Comparative Examples 1-2 all used the same process flow as Example 1, with the differences listed in Table 1.

[0044] The content ratio in Table 1 represents the mass ratio based on the mass of the composite insulator silicone rubber.

[0045] Table 1

[0046] Test Example The physical property test data of the composite insulator silicone rubber prepared in the examples and comparative examples are shown in Table 2.

[0047] The tear strength was determined according to the standard of GB / T 529-2008 “Determination of tear strength of vulcanized or thermoplastic rubber”; The tensile strength and elongation at break were determined according to the standard of GB / T 528-2009 “Determination of tensile stress-strain properties of vulcanized or thermoplastic rubber”; The test method of volume resistivity and surface resistivity was as follows: the volume resistivity and surface resistivity were determined according to the standard of GB / T 31838-2019 “Solid insulating materials - Determination of the dielectric and resistive properties”; The breakdown strength was determined according to the standard of GB / T 1408-2016 “Insulating materials - Determination of the electrical strength”;

[0048] The aging process used a UVB-313 light source with an irradiation intensity of 0.71 W / m², and the standard was GB / T 16422.3-2022. After the aging process, the physical properties of the composite insulator silicone rubber prepared in each example and comparative example after aging were determined, and the physical property decline rate was calculated according to formula (1).

[0049]

[0050] Table 2

[0051] Table 2 (continued)

[0052] From the above results, it can be seen that the composite insulator silicone rubber provided by the application has more excellent mechanical properties and electrical properties, the physical property decline rate is smaller after 1000 h of ultraviolet accelerated aging, the service life is significantly prolonged, and the outdoor aging problem of the composite insulator silicone rubber can be effectively solved, thereby ensuring the safe and stable operation of the power transmission line.

[0053] The preferred embodiments of the application are described in detail above, but the application is not limited thereto. Within the technical concept of the application, various simple modifications can be made to the technical solutions of the application, including the combination of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as disclosed by the application and fall within the protection scope of the application.

Claims

1. A composition for composite insulator silicone rubber, characterized by, The composition contains a main agent and an auxiliary agent; the main agent contains an anti-ultraviolet system, silicone rubber, reinforcing agent and flame retardant; the anti-ultraviolet system includes benzotriazole ultraviolet absorber and inorganic filler; The content of the anti-ultraviolet system is 6-11wt%, the content of the silicone rubber is 40-42wt%, the content of the reinforcing agent is 10-15wt%, and the content of the flame retardant is 35-38wt% based on the total weight of the composition; In the anti-ultraviolet system, the mass ratio of the benzotriazole ultraviolet absorber to the inorganic filler is 1:6-22.

2. The composition of claim 1, wherein, The average particle size of the benzotriazole ultraviolet absorber is 5-20µm; And / or, the benzotriazole ultraviolet absorber is selected from at least one of UV-328, UV-326.

3. The composition of claim 1, wherein, The weight average diameter of the inorganic filler is 30-50nm; And / or, the inorganic filler is selected from at least one of nano-TiO2 and nano-ZnO.

4. The composition according to any one of claims 1 to 3, characterized in that, The maximum particle size of the flame retardant is 4-6µm, and the median particle size is 1-3µm; And / or, the flame retardant is micron-level aluminum hydroxide.

5. The composition according to any one of claims 1 to 3, wherein The auxiliary agent contains structure control agent, vulcanizing agent, softening agent and coupling agent; And / or, the content of the structure control agent is 0.5-3wt%, the content of the vulcanizing agent is 0.15-0.18wt%, the content of the softening agent is 0.1-0.3wt%, and the content of the coupling agent is 0.8-0.9wt% based on the total weight of the composition.

6. A method of preparing a composite insulator silicone rubber, characterized by, The method applies each component in the composition of any one of claims 1-5, comprising: (1) first mixing silicone rubber, benzotriazole ultraviolet absorber, inorganic filler, reinforcing agent, flame retardant, structure control agent, softening agent and coupling agent in the auxiliary agent to obtain a mixed material I; (2) performing rubber mixing treatment on the mixed material I to obtain a rubber mixing product; (3) adding vulcanizing agent to the rubber mixing product for vulcanization treatment to obtain the composite insulator silicone rubber.

7. The method of claim 6, wherein, In step (1), the first mixing conditions include: temperature ≤70℃, time 0.8-1.2h, and stirring speed 10-20rpm.

8. The method according to claim 6 or 7, characterized in that, In step (2), the rubber mixing treatment is performed on a two-roll open mill; And / or, the operating conditions of the two-roll open mill include: roll gap 18-22mm.

9. The method according to claim 6 or 7, characterized in that, In step (3), the vulcanization treatment conditions include: temperature 120-160℃, pressure 8-12MPa, and time 8-12min.

10. The composite insulator silicone rubber prepared by the method of any one of claims 6-9; And / or, the composite insulating silicone rubber has a breakdown strength of ≥ 24.9 kV / mm, a volume resistivity of ≥ 8.2 x 10 13 Ω·m, a tear strength of ≥ 16.7 kN / m, and a tensile strength of ≥ 4.3 MPa.

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