WO2019056347A1

WO2019056347A1 - Polysiloxane composition

Info

Publication number: WO2019056347A1
Application number: PCT/CN2017/103111
Authority: WO
Inventors: Junnan WU (Andy); Dongbing JIN (Jason); Zhengkun YIN (David); Wei WANG (Alma)
Original assignee: Wacker Chemie Ag
Priority date: 2017-09-25
Filing date: 2017-09-25
Publication date: 2019-03-28
Also published as: CN111051449B; CN111051449A

Abstract

Provided is an addition-curing silicone coating composition, comprising vinyl polysiloxanes, reinforcing fillers, hydrogen polysiloxanes, multifunctional alkoxysilanes and the like. The composition can be used in the field of coatings for power transmission and distribution equipment for power systems，preferably in the field of insulator coatings.

Description

[Title established by the ISA under Rule 37.2] POLYSILOXANE COMPOSITION

Field of the Invention

The present invention relates to a solvent-free anti-pollution flashover silicone coating in the technical field of coatings for power transmission and distribution equipment for power systems.

Background of the Invention

CN104694004A discloses a solvent-free, addition-curing, anti-pollution flashover silicone coating comprising vinyl polysiloxanes, silicon-hydride containing polysiloxanes, vinyl MQ silicone resins, polydimethylsiloxanes having viscosity of 100mPa.s and a chloroplatinic acid catalyst.

US4476155 discloses in comparative construction D therein an addition-curing silicone coating for insulators comprising hydrocarbon-based organic solvents, aluminum hydroxide, vinyl polysiloxanes and methyl phenyl polysiloxanes, wherein the product has an oil-bleeding property, and the vinyl polysiloxane has a very high molecular weight and is typically a gum having viscosity greater than 1,000,000 mPa.s.

Summary of the Invention

The present invention discloses a polysiloxane composition which features good thixotropic properties, an adequate viscosity (capable of rapidly shear-thinning at high shear rates) , and a fast heat-curing speed. The polysiloxane composition in the present invention contains no organic solvents or volatiles. It is environmentally friendly, when used as an insulator coating, and can greatly reduce the health risks of construction workers. This coating exhibits high adhesion strength on insulators of inorganic materials and provides an excellent self-cleaning property for finished insulator products.

The polysiloxane composition can be applied in a dipping process, greatly shortening the preparation time of the insulator coating and thus improving the production efficiency. In an appropriate dipping process, a thinner, uniform coat with an average thickness of 0.3-0.5mm can be obtained, which reduces the use of the coating and the production costs of insulators.

The present invention discloses a polysiloxane composition comprising

(a) one or more vinyl polysiloxanes having viscosity of from 10 to 100,000 mPa.s；

(b) one or more reinforcing fillers 1, composed of silica；

(c) one or more hydrogen polysiloxanes；

(d) one or more multifunctional alkoxysilanes and oligomers thereof, wherein the multifunctional alkoxysilane have a structural formula as shown in (i) ；

where R¹, R² and R³ are independently selected from among C1-C4 alkyl groups and C1-C4 alkoxy groups and can be the same or different, at least one of which is an alkoxy group； R is selected from among C1-C3 alkylene groups；

A is a reactive functional group selected from group A1 consisting of epoxypropoxy and 3, 4-epoxycyclohexyl and/or group A2 consisting of methacryloxy and acryloxy；

(f) one or more lubricating polysiloxanes selected from the group consisting of methyl phenyl polysiloxane, methyl (long chain alkyl) polysiloxane and methyl trifluoropropyl polysiloxane；

(g) a catalytic amount of one or more hydrosilylation catalysts.

The composition as mentioned above, comprising

(a) 50-60 wt％of one or more vinyl polysiloxanes having viscosity of from 500 to 100,000 mPa.s；

(b) 5-10 wt％of one or more reinforcing fillers 1, composed of silica having a BET surface area between 50-380m²/g；

(c) 10-15 wt％of one or more hydrogen polysiloxanes；

(d) 0.1 to 3 wt％of one or more multifunctional alkoxysilanes and oligomers thereof,

wherein the multifunctional alkoxysilane have a structural formula as shown in (i) :

(e) one or more alkynol inhibitors (including ethynylcyclohexanol, 3, 5-dimethyl-1-hexyn-3-ol) ；

(f) 0.2-5 wt％of one or more methyl phenyl polysiloxanes having viscosity of from 1 to 5,000 mPa.s, preferably from 100 to 5,000 mPa.s, and a refractive index of greater than 1.42, preferably greater than 1.49；

(g) a catalytic amount of one or more hydrosilylation catalysts,

wherein the figures in wt％in each case, based on the total weight of the composition, add up to 100 wt％.

The composition as mentioned above, characterized in that Component (a) contains two or more vinyl polysiloxanes, including vinyl polysiloxanes (a1) having viscosity of greater than 10,000 mPa.s and a vinyl content of from 0.02 to 0.1 mmol/g and vinyl polysiloxanes (a2) having viscosity of less than 2,000 mPa.s and a vinyl content of from 0.1 to 5 mmol/g.

The composition as mentioned above, characterized in that Component (c) contains two or more hydrogen polysiloxanes, and including hydrogen-terminated polysiloxanes (c1) with a hydrogen content of from 0.01 to 1 mmol/g and polysiloxanes with Si-H side groups (c2) with a hydrogen content of from 3 to 15 mmol/g, wherein the weight ratio of Component (c1) to Component (c2) is between 1.5 and 4.

The composition as mentioned above, characterized in that it contains less than 1 wt％of an organic solvent, preferably less than 0.01 wt％, based on the weight of the composition.

The composition as mentioned above, characterized in that Component (d) contains multifunctional alkoxysilanes (d1) , wherein A is selected from group A1 consisting of epoxypropoxy and 3, 4-epoxycyclohexyl, and multifunctional alkoxysilanes (d2) , wherein A is selected from group A2 consisting of methacryloxy and acryloyloxy.

The composition as mentioned above, characterized in that the weight ratio of Component (d1) to Component (d2) is between 2 and 4.

The composition as mentioned above, characterized in that Component (d) contains (3-epoxy propoxy propyl) trimethoxysilane (d1) and 3-methacryloxypropyl-trimethoxysilane (d2) .

The composition as mentioned above, characterized by Component (g) , hydrosilylation catalysts, such as a Karstedt's catalyst, chloroplatinic acid, and chloroplatinic acid-tetramethyltetravinylcyclotetrasiloxane complex, wherein the concentration of Pt atoms in the composition is from 10 to 100 ppm,

The composition as mentioned above, characterized in that it further contains 15-30 wt％filler 2 (Component (h) ) comprising talc, aluminum hydroxide, precipitated calcium carbonate, ground calcium carbonate, having a particle size ranging from 200 to 400 meshes, wherein talc is present in an amount of more than 40 wt％of filler 2 and aluminum hydroxide less than 10 wt％of filler 2, based on the total weight of filler 2. The composition as mentioned above, characterized in that the viscosity of the composition is measured at 25℃ according to DIN EN ISO 3219, wherein the viscosity D ＝ 0.5 s^-1 is between 15,000 and 50,000 mPa.s and the viscosity D ＝ 25 s^-1 between 4,000 and 8,000 mPa.s； preferably the viscosity D ＝ 0.5 s^-1 between 15,000 and 30,000 mPa.s and D ＝ 25 s^-1 between 4,000-6,000 mPa.s.

The composition as mentioned above, characterized in that it is a product in the form of a one-component package.

The composition as mentioned above, characterized in that it is cured for 10 to 50 min at a temperature from 100 to 140 ℃.

The composition as mentioned above, characterized in that the composition can be stably stored for 6 months and above at 5-25℃ in a dark condition, and the change in viscosity of the composition during storage is less than or equal to 50％.

A use of the composition as mentioned above in the field of coatings for power transmission and distribution equipment for power systems, preferably in the field of insulator coatings.

The use as mentioned above, characterized in that the insulator material is inorganic, preferably glass and ceramic.

The use as mentioned above, characterized in that the composition is applied in a dipping process comprising low-temperature heating of the tank for storing the coating (the in-tank composition is less than or equal to 90℃) and non-contact heating of the coating on the surface of the insulator during the rotation process (ensuring the temperature of the composition on the insulator surface is higher than or equal to 100℃) .

The “coating for power transmission and distribution equipment for power systems” herein refers to coatings designed for power grids, power stations, transmission system and consumers to eliminate the risk of pollution flashover. The “insulator coating field” herein refers to the technical filed of RTV silicone rubber anti-pollution flashover coatings for insulators involved in the Electric Power Industry Standard of China DL /T 627-2012.

The “methyl phenyl polysiloxane” herein refers to a category of products listed in Section 2.2.2 “Preparation of Methylphenyl Silicone Oils” in Silicone Oils and Its Derived Products, Chemical Industry Press, China, 2004, which have viscosity of preferably from 1 to 5,000 mPa.s, more preferably from 100 to 5,000 mPa.s, and a refractive index of greater than 1.42, preferably greater than 1.49.

The “methyl (long chain alkyl) polysiloxane” herein refers to a category of products listed in Section 3.8 “Methyl (Long-chain Alkyl) Silicone Oils” in Silicone Oils and Its Derived Products, Chemical Industry Press, China, 2004, wherein the long-chain alkyl content is preferably greater than or equal to 1 mol％, more preferably greater than or equal to 10 mol％, based on the total number of siloxane units.

The “methyl trifluoropropyl polysiloxane” herein refers to a category of products listed in Section 3.9 “Methyl Trifluoropropyl Silicone Oils” in Silicone Oils and Its Derived Products, Chemical Industry Press, China, 2004, wherein the trifluoropropyl content is preferably greater than or equal to 1 mol％, more preferably greater than or equal to 10 mol％, based on the number of moles of siloxane units.

The “organic solvent” herein refers to solvents with an organic compound as medium, such as methanol, heptane, hexane, pentane, benzene, toluene, gasoline and dichloromethane.

The “oligomer” of one or more multifunctional alkoxysilanes herein refers to the polycondensates of one or more silanes of formula (i) having a degree of polymerization of from 2 to 10, obtained by a controlled hydrolysis with or without a catalyst, such as the oligomers described in CN 101189281B, CN 101367939A, CN 101367939B, US5385955 and US4378250.

Filler 2 (h) herein is an inorganic mineral powder having a particle size ranging from 200 to 400 meshes, excluding silica.

Detailed Description of the Preferred Embodiments

Vinyl polysiloxane 1: a vinyl-terminated polysiloxane with a vinyl content of 0.04 mmol/g, having viscosity of 20,000 mPa.s measured by rheometer ANTON PAAR MCR-302 at 25℃ according to DIN 53019.

Vinyl polysiloxane 2: a vinyl-terminated polysiloxane with a vinyl content of 0.13 mmol/g, having viscosity of 1,000 mPa.s at 25 ℃ according to DIN 53019.

Fumed silica 1: a hydrophilic pyrogenic silica having a BET surface area of 300 m²/g.

Fumed silica 2: a hydrophilic pyrogenic silica having a BET surface area of 130 m²/g.

Hydrogen polysiloxane 1: a hydrogen-terminated polysiloxane with a hydrogen content of 0.5 mmol/g, having viscosity of 60 mPa.s at 25℃ according to DIN 53019.

Hydrogen polysiloxane 2: a silicone oil with Si-H side groups with a hydrogen content of 11.5 mmol g, having viscosity of 30 mPa.s at 25℃ according to DIN 53019.

Methyl phenyl polysiloxane: having viscosity of 150 mPa.s at 25℃ according to DIN 53019 and a refractive index of greater than or equal to 1.49.

The above-mentioned substances are supplied by Wacker Chemie AG.

Talc: 320 mesh (particle size)

Silicone resin: a vinyl MQ silicone resin having a vinyl content of 0.73 mmol/g, M/Q ＝ 0.72 and weight average molecular weight Mw ＝ 5,300

Table 1 Coating Compositions

In Table 1, the catalyst is a Karstedt’s catalyst and the Pt atoms in each of the compositions are at a concentration of about 30 ppm. The inhibitor is ethynylcyclohexanol, the concentration of which is about 340 ppm in each of the compositions.

Base 1 and Base 2 can be prepared by the methods disclosed in CN 101747516B, US5854343 or EP0622421B1, and US5506303A. Here's how the Bases are typically prepared: One or more vinyl polysiloxanes (polysiloxanes containing at least 2 Si-Vi groups) , reinforcing filler 1, optional filler 2 (including optional flame-retardant fillers) and other components are mixed well in high-shear dispersing equipment (including extruders, kneaders or high-speed dispersers) , and heated and/or vacuumed to remove low-molecular volatiles, followed by grinding and filtration process to obtain the Base.

The reinforcing filler 1 can be any one, or a combination, of fumed silicas, precipitated silicas, surface-hydrophobized fumed silicas and surface-hydrophobized precipitated silicas, which have a specific surface area of from 50 to 380 m²/g. Depending on the type of reinforcing filler 1 used and whether or not it is subjected to surface hydrophobicity, a hydrophobizion agent (including hexamethylsilazane and trimethylsilanol) and water can also be added in during the preparation of the above-mentioned Base. The above selections are known to those skilled in the art.

The method for preparing the polysiloxane composition in the present invention is as follows:

At room temperature, the following steps are carried out in a shear mixing device (e.g., a double planetary mixer) :

(1) uniformly mix Base 1 and Base 2 in Table 1, vinylpolysiloxane (a) , hydrogen polysiloxane (c) , and methyl phenyl polysiloxane (f) ；

(2) add in talc in proportions and mix well；

(3) add in silane and mix well；

(4) add in inhibitor (e) and hydrosilylation catalyst (g) in sequence, and mix well. Apply the vacuum and store in a sealed condition.

The individual coating compositions in Table 1 are products in a one-component package.

Viscosity test:

The dynamic viscosity (D＝0.5 s^-1 and D＝25 s^-1) of the individual coating compositions in Table 1 is tested at 25℃ according to DIN EN ISO 3219 using ANTON PAAR MCR-302.

How to use: dipping process of insulators See the relevant descriptions in CN104637636A. However, the coating in a tank should be heated at a low temperature (the in-tank composition’s temperature is less than or equal to 90℃) , while the coating is heated in a non-contact manner during the rotation process (ensuring the temperature of the composition on the insulator surface is higher than or equal to 100℃) , and the curing time is significantly reduced.

Sample preparation:

A 100 x 25 x 5mm glass slide was immersed vertically in a coating composition in Table 1, taken out vertically after 30 s, and let to drip down vertically for 60 s.

The slide was transferred to an oven, with the coated side placed vertically to the horizontal plane, to cure at 140℃ for 10 min, and then taken out to cool down to room temperature.

It is known to those skilled in the art that the curing time can be shortened as the curing temperature is increased； that is, the coatings can fully cure at 100 ℃ for 50 min or at 140 ℃ for 10 min.

A knife was used to scrape, in parallel to surface of slide, a piece of cured coating for a length of about 3 cm and the coating film was peeled off at 90 degrees reversely.

Thickness test:

The thickness of the peeled coating film was measured with a vernier caliper.

Adhesion test

Observe the stripping surface:

In the reverse peeling at 90 degrees, the adhesion is rated “Poor” if no residual rubber is found between the coating film and the glass surface and the peeling is easy.

In the reverse peeling at 90 degrees, the adhesion is rated “Good” if the coating film itself is damaged.

Self-cleaning test

A mold having a thickness of 2 mm was used to make an A4-sized sheet specimen by pressing that is cured at 165 ℃ for 5 min.

According to the thin film method specified in Section C. 4 under the Electric Power

Industry Standard of China DL /T 627-2012, the self-cleaning property is rated “Poor” if an adsorption force exists between the specimen surface and the film as described in (3) -a) therein, and “Good” if no adsorption force exists between the specimen surface and the film as described in (3) -b) .

Tensile, shear and hardness tests

A mold having a thickness of 2 mm was used to make a sheet specimen by pressing that is cured at 165 ℃ for 5 min. The tear test slabs were prepared and the test data are acquired according to ASTM D 624B, while the tensile and shear test slabs prepared and the test data acquired according to ISO 37 Type 1, and the hardness test samples prepared and the hardness tested according to ISO 7619-1.

The performance test data of the coatings made of the polysiloxane composition in the present invention are shown in Table 2.

Table 2

Typical properties	Ex. 1	Ex. 2	C. Ex. 2	C. Ex. 1	C. Ex. 3	C. Ex. 4
Viscosity D＝0.5 (mPa.s)	45 800	22 500	22 400	26 500	22 600	21 300
Viscosity D＝25 (mPa.s)	7 720	5 030	5 840	7 340	5 730	5 360
SHORE A	41	39	41	45	42	45
Tensile strength (MPa)	3.25	3.23	3.1	3.83	3.6	2.9
Elongation at break	227	250	200	188	206	175
Tear strength (MPa)	6.03	5.9	6.2	7.3	6.3	6.8
Thickness (mm)	0.5	0.29	0.3	0.45	0.3	0.28
Self-cleaning property	Good	Good	Good	Poor	Poor	Good
Adhesion	Good	Good	Poor	Poor	Good	Poor

The silane of Comparative Example 2 does not belong to the multifunctional alkoxysilane (d) described in the present invention and has a poor adhesion. The silicone resin used in Comparative Example 1 can not improve the adhesion of the product. In the insulator’s lifecycle, the coating with a poor adhesion is prone to peeling off.

Comparative Example 1 and Comparative Example 3 do not contain methylphenyl silicone oils and have a poor self-cleaning property, and the resulting coatings are easily contaminated and have a poor resistance to anti-pollution flashover in the insulator’s lifecycle.

Claims

A polysiloxane composition comprising

(a) one or more vinyl polysiloxanes having viscosity of from 10 to 100,000 mPa.s；

(b) one or more reinforcing fillers 1, composed of silica；

(c) one or more hydrogen polysiloxanes；

(d) one or more multifunctional alkoxysilanes and oligomers thereof, wherein the multifunctional alkoxysilane have a structural formula as shown in (i) ；

where R¹, R² and R³ are independently selected from among C1-C4 alkyl groups and C1-C4 alkoxy groups and can be the same or different, at least one of which is an alkoxy group； R is selected from among C1-C3 alkylene groups；

A is a reactive functional group selected from group A1 consisting of epoxypropoxy and 3, 4-epoxycyclohexyl and/or group A2 consisting of methacryloxy and acryloxy；

(f) one or more lubricating polysiloxanes selected from the group consisting of methyl phenyl polysiloxane, methyl (long chain alkyl) polysiloxane and methyl trifluoropropyl polysiloxane；

(g) a catalytic amount of one or more hydrosilylation catalysts.
The composition according to Claim 1, comprising

(a) 50-60 wt％of one or more vinyl polysiloxanes having viscosity of from 500 to 100,000 mPa.s；

(b) 5-10 wt％of one or more reinforcing fillers 1, composed of silica having a BET surface area between 50-380m²/g；

(c) 10-15 wt％of one or more hydrogen polysiloxanes；

(d) 0.1 to 3 wt％of one or more multifunctional alkoxysilanes and oligomers thereof, wherein the multifunctional alkoxysilane have a structural formula as shown in (i) :

where R¹, R² and R³ are independently selected from among C1-C4 alkyl groups and C1-C4 alkoxy groups and can be the same or different, at least one of which is an alkoxy group； R is selected from among C1-C3 alkylene groups；

A is a reactive functional group selected from group A1 consisting of epoxypropoxy and 3, 4-epoxycyclohexyl and/or group A2 consisting of methacryloxy and acryloxy；

(e) one or more alkynol inhibitors (including ethynylcyclohexanol, 3, 5-dimethyl-1-hexyn-3-ol) ；

(f) 0.2-5 wt％of one or more methyl phenyl polysiloxanes having viscosity of from 1 to 5,000 mPa.s, preferably from 100 to 5,000 mPa.s, and a refractive index of greater than 1.42, preferably greater than 1.49；

(g) a catalytic amount of one or more hydrosilylation catalysts,

wherein the figures in wt％in each case, based on the total weight of the composition, add up to 100 wt％.
The composition according to Claim 1 or 2, characterized in that Component (a) contains two or more vinyl polysiloxanes, including vinyl polysiloxanes (a1) having viscosity of greater than 10,000 mPa.s and a vinyl content of from 0.02 to 0.1 mmol/g and vinyl polysiloxanes (a2) having viscosity of less than 2,000 mPa.s and a vinyl content of from 0.1 to 5 mmol/g.
The composition according to any in Claim 1-3, characterized in that Component (c) contains two or more hydrogen polysiloxanes, and including hydrogen-terminated polysiloxanes (c1) with a hydrogen content of from 0.01 to 1 mmol/g and polysiloxanes with Si-H side groups (c2) with a hydrogen content of from 3 to 15 mmol/g, wherein the weight ratio of Component (c1) to Component (c2) is between 1.5 and 4.
The composition according to any in Claim 1-3, characterized in that Component (d) contains multifunctional alkoxysilanes (d1) , wherein A is selected from group A1 consisting of epoxypropoxy and 3, 4-epoxycyclohexyl, and multifunctional alkoxysilanes (d2) , wherein Ais selected from group A2 consisting of methacryloxy and acryloyloxy.
The composition according to Claim 5, characterized in that the weight ratio of Component (d1) to Component (d2) is between 2 and 4.
The composition according to Claim 5 or 6, characterized in that Component (d) contains (3-epoxy propoxy propyl) trimethoxysilane (d1) and 3-methacryloxypropyltrimethoxysilane (d2) .
The composition according to any in Claim 1-7, characterized in that it further contains 15-30 wt％filler 2 (Component (h) ) comprising talc, aluminum hydroxide, precipitated calcium carbonate, ground calcium carbonate, having a particle size ranging from 200 to 400 meshes, wherein talc is present in an amount of more than 40 wt％of filler 2 and aluminum hydroxide less than 10 wt％of filler 2, based on the total weight of filler 2.
The composition according to any in Claim 1-8, characterized in that the viscosity of the composition is measured at 25℃ according to DIN EN ISO 3219, wherein the viscosity D ＝ 0.5 s^-1 is between 15,000 and 50,000 mPa.s and the viscosity D ＝ 25 s^-1 between 4,000 and 8,000 mPa.s； preferably the viscosity D ＝ 0.5 s^-1 between 15,000 and 30,000 mPa.s and D ＝ 25 s^-1 between 4,000-6,000 mPa.s.
The composition according to any in Claim 1-8, characterized in that it is a product in the form of a one-component package.
The composition according to any in Claim 1-8, characterized in that the composition can be stably stored for 6 months and above at 5-25℃ in a dark condition, and the change in viscosity of the composition during storage is less than or equal to 50％.
A use of the composition according to any in Claim 1-1 in the field of coatings for power transmission and distribution equipment for power systems, preferably in the field of insulator coatings.
The use according to Claim 12, characterized in that the composition is applied in a dipping process comprising low-temperature heating of the tank for storing the coating (the in-tank composition is less than or equal to 90℃) and non-contact heating of the coating on the surface of the insulator during the rotation process (ensuring the temperature of the composition on the insulator surface is higher than or equal to 100℃) .