Coating composition, explosion-proof coating and coating piezoresistor

Abstract

The invention provides a coating composition. The coating composition comprises polyurethane modified epoxy resin, polyether amine, metal hydroxide and an inorganic thixotropic agent. According to the coating composition, the complete explosion-proof coating is arranged on the outer surface of the piezoresistor in a dip coating mode, automatic operation can be achieved, manpower cost is not needed, finished products can have the unified specification, and the yield and reliability of the finished products are guaranteed. The invention also provides an explosion-proof coating and a coating piezoresistor coated by the explosion-proof coating, and the explosion-proof coating and the coating piezoresistor have excellent explosion-proof performance.

Description

Technical Field

[0001] The present invention relates to a coating composition, an explosion-proof coating obtained by curing the coating composition, and a coated varistor coated with the explosion-proof coating. Background Art

[0002] A varistor, also known as a surge absorber or rheostat, can change its resistance value in response to changes in external voltage, thereby shunting the current to reduce the risk of permanent damage to important electronic products caused by sudden excessive voltage. However, when the varistor is subjected to an excessive instantaneous voltage and cannot withstand it, the current value of the varistor and the temperature of the component itself will increase exponentially. At the moment when the high-density current breaks down the varistor, phenomena such as sparks, combustion, or explosion may occur. In addition to possibly damaging other adjacent electronic components, it may even trigger a fire. Therefore, an explosion-proof function needs to be added to the design of the varistor.

[0003] There are two common explosion-proof measures for varistors: (1) using a polyvinyl chloride (PVC) heat shrinkable tube to cover the varistor; and (2) placing the varistor in an explosion-proof housing and further filling it with a flame retardant material. However, the volume of the varistor is very small, resulting in extremely cumbersome operations for sleeving the heat shrinkable tube or the explosion-proof housing and relying on manual labor, which leads to the problem of high cost. Therefore, more cost-effective explosion-proof measures need to be developed. Summary of the Invention

[0004] To solve the above problems, the present invention provides a coating composition, comprising: a resin, a hardener, a filler, and a thixotropic agent; wherein, the resin comprises a polyurethane-modified epoxy resin, the hardener comprises a polyetheramine, the filler comprises a metal hydroxide, the thixotropic agent comprises an inorganic thixotropic agent, and based on 100 parts by weight of the total weight of the resin, the hardener, the filler, and the thixotropic agent, the weight ratio of the polyurethane-modified epoxy resin to the polyetheramine is 1.5 to 2.3:1, the content of the metal hydroxide is 15 parts by weight to 55 parts by weight, and the inorganic thixotropic agent is 1.7 parts by weight to 4.16 parts by weight.

[0005] The polyurethane-modified epoxy resin of the present invention is a resin. When a polyetheramine used as a hardener is added, a 3D network structure can be jointly formed to improve the explosion-proof performance. The coating composition of the present invention is in a liquid state, so an instrument can be set to immerse the varistor in the coating composition of the present invention in an automated manner, that is, a complete explosion-proof coating can be provided on the outer surface of the varistor by means of automated dipping. This not only does not rely on manual labor and can reduce costs, but also enables the finished product to have a unified specification to ensure the yield and reliability of the finished product.

[0006] In one embodiment, based on the total weight of the resin, the hardener, the filler, and the thixotropic agent being 100 parts by weight, the weight ratio of the polyurethane-modified epoxy resin to the polyetheramine is 1.7 to 2.1:1. Preferably, the weight ratio of the polyurethane-modified epoxy resin to the polyetheramine is 1.8 to 2.0:1. More preferably, the weight ratio of the polyurethane-modified epoxy resin to the polyetheramine is 1.85 to 1.95:1.

[0007] In one embodiment, based on the total weight of the resin, the hardener, the filler, and the thixotropic agent being 100 parts by weight, the content of the polyurethane-modified epoxy resin is 28.1 parts by weight to 55.5 parts by weight, the content of the polyetheramine is 14.85 parts by weight to 29.5 parts by weight, the content of the metal hydroxide is 15 parts by weight to 55 parts by weight, and the inorganic thixotropic agent is 1.7 parts by weight to 4.16 parts by weight.

[0008] Preferably, based on the total weight of the resin, the hardener, the filler, and the thixotropic agent being 100 parts by weight, the content of the polyurethane-modified epoxy resin is 28.5 parts by weight to 55 parts by weight, for example: 28.5 parts by weight, 29 parts by weight, 30 parts by weight, 33 parts by weight, 36 parts by weight, 39 parts by weight, 42 parts by weight, 45 parts by weight, 48 parts by weight, 50 parts by weight, 51 parts by weight, 52 parts by weight, 53 parts by weight, 54 parts by weight, or 55 parts by weight.

[0009] Preferably, based on the total weight of the resin, the hardener, the filler, and the thixotropic agent being 100 parts by weight, the content of the polyetheramine is 15 parts by weight to 29 parts by weight, for example: 15 parts by weight, 15.5 parts by weight, 16 parts by weight, 18 parts by weight, 20 parts by weight, 22 parts by weight, 24 parts by weight, 26 parts by weight, 27 parts by weight, 27.5 parts by weight, 28 parts by weight, 28.5 parts by weight, or 29 parts by weight.

[0010] Preferably, based on the total weight of the resin, the hardener, the filler, and the thixotropic agent being 100 parts by weight, the content of the metal hydroxide is 15.2 parts by weight to 54.5 parts by weight, for example: 15.2 parts by weight, 17 parts by weight, 19 parts by weight, 20 parts by weight, 25 parts by weight, 30 parts by weight, 35 parts by weight, 40 parts by weight, 45 parts by weight, 47 parts by weight, 49 parts by weight, 51 parts by weight, 52 parts by weight, 53 parts by weight, 54 parts by weight, or 54.5 parts by weight.

[0011] Preferably, based on the total weight of the resin, the hardener, the filler, and the thixotropic agent being 100 parts by weight, the inorganic thixotropic agent is 1.71 to 4.1 parts by weight, such as: 1.71 parts by weight, 1.8 parts by weight, 1.9 parts by weight, 2 parts by weight, 2.3 parts by weight, 2.6 parts by weight, 2.9 parts by weight, 3.2 parts by weight, 3.5 parts by weight, 3.7 parts by weight, 3.8 parts by weight, 3.9 parts by weight, 4 parts by weight, or 4.1 parts by weight.

[0012] In one embodiment, the content of the polyurethane-modified epoxy resin is 30.6 to 51.5 parts by weight, the content of the polyetheramine is 16.2 to 27.3 parts by weight, the content of the metal hydroxide is 19.9 to 51 parts by weight, and the inorganic thixotropic agent is 1.73 to 3.74 parts by weight.

[0013] In one embodiment, the metal hydroxide includes any one or a combination of aluminum hydroxide and magnesium hydroxide. Preferably, the D 50 of the metal hydroxide is 10 to 25 microns, such as: 10 microns, 13 microns, 16 microns, 19 microns, 22 microns, or 25 microns. More preferably, the D 50 of the metal hydroxide is 15 to 20 microns.

[0014] According to the present invention, the D 50 is the diameter value of the fine particles, and 50% of the total amount of the fine particles is less than this diameter value. In addition, the D 50 is obtained by analyzing with a laser particle size analyzer.

[0015] The metal hydroxide of the present invention as a filler can improve the explosion-proof performance of the explosion-proof coating obtained by curing the coating composition of the present invention.

[0016] In one embodiment, the inorganic thixotropic agent includes silicate. Preferably, the silicate is plate-shaped silicate.

[0017] In one embodiment, the loose bulk density of the inorganic thixotropic agent is 30 kg / m 3 to 180 kg / m 3 , such as: 30 kg / m 3 , 50 kg / m 3 , 80 kg / m 3 , 110 kg / m 3 , 140 kg / m 3 , 170 kg / m 3 or 180 kg / m 3 . Preferably, the loose bulk density of the inorganic thixotropic agent is 34 kg / m 3 to 172 kg / m 3。

[0018] In one embodiment, the D of the inorganic thixotropic agent 50 is 25 to 35 microns. Preferably, the D of the inorganic thixotropic agent 50 is 28 to 32 microns.

[0019] The inorganic thixotropic agent of the present invention is used to adjust the consistency of the coating composition of the present invention. In addition, after the coating composition of the present invention is cured into an explosion-proof coating, the inorganic thixotropic agent of the present invention still exists in the explosion-proof coating.

[0020] In one embodiment, the epoxy equivalent of the polyurethane-modified epoxy resin is 76 g / eq to 250 g / eq, for example: 76 g / eq, 80 g / eq, 90 g / eq, 100 g / eq, 110 g / eq, 130 g / eq, 150 g / eq, 180 g / eq, 200 g / eq, 230 g / eq or 250 g / eq. Preferably, the epoxy equivalent of the polyurethane-modified epoxy resin is 190 g / eq to 245 g / eq. More preferably, the epoxy equivalent of the polyurethane-modified epoxy resin is 195 g / eq to 240 g / eq.

[0021] The epoxy equivalent weight (E.E.W) refers to the amount of resin containing one epoxy group, and the calculation formula is: epoxy equivalent = average molecular weight of epoxy resin / number of epoxy groups contained in each molecule.

[0022] In one embodiment, the active hydrogen equivalent of the polyetheramine is 40 g / eq to 150 g / eq, for example: 40 g / eq, 50 g / eq, 55 g / eq, 60 g / eq, 65 g / eq, 70 g / eq, 80 g / eq, 90 g / eq, 100 g / eq, 110 g / eq, 120 g / eq, 130 g / eq, 140 g / eq or 150 g / eq.

[0023] The active hydrogen equivalent weight (AHEW) refers to the amount of amine containing one active hydrogen, and the calculation formula is: active hydrogen equivalent = molecular weight of amine / number of active hydrogen atoms.

[0024] Preferably, the polyetheramine includes any one or a combination of polyetheramine D400 and polyetheramine D230.

[0025] In one embodiment, the ratio of the total number of epoxy groups in the content of the polyurethane-modified epoxy resin to the total number of active hydrogen atoms in the content of the polyetheramine is 0.9 to 1.1:0.9 to 1.1. Preferably, the ratio of the total number of epoxy groups in the content of the polyurethane-modified epoxy resin to the total number of active hydrogen atoms in the content of the polyetheramine is 0.95 to 1.05:0.95 to 1.05. More preferably, the ratio of the total number of epoxy groups in the content of the polyurethane-modified epoxy resin to the total number of active hydrogen atoms in the content of the polyetheramine is 0.98 to 1.02:0.98 to 1.02.

[0026] In one embodiment, the ratio of the total number of epoxy groups in the content of the polyurethane-modified epoxy resin to the total number of active hydrogen atoms in the content of the polyetheramine is 1:1, that is, the quantities are the same.

[0027] According to the present invention, when the total number of epoxy groups in the content of the polyurethane-modified epoxy resin is the same as the total number of active hydrogen atoms in the content of the polyetheramine, the explosion-proof coating obtained by curing the coating composition of the present invention can have the best explosion-proof performance.

[0028] In one embodiment, the coating composition of the present invention further comprises a dispersant. The use of a dispersant in the present invention helps to accelerate the dispersion of the metal hydroxide. In addition, when the coating composition of the present invention is cured into an explosion-proof coating, the dispersant will not be present in the explosion-proof coating, so the dispersant does not affect the explosion-proof performance of the explosion-proof coating.

[0029] In one embodiment, the dispersant comprises any one or a combination thereof of phosphate ester, alkylphosphate, and polyoxyethylene ether phosphate.

[0030] Preferably, based on 100 parts by weight of the total weight of the resin, the hardener, the filler, and the thixotropic agent, the content of the dispersant is 0.25 parts by weight to 1.375 parts by weight, for example: 0.25 parts by weight, 0.3 parts by weight, 0.5 parts by weight, 0.7 parts by weight, 0.9 parts by weight, 1.1 parts by weight, 1.2 parts by weight, or 1.375 parts by weight.

[0031] In one embodiment, based on 100 parts by weight of the total weight of the resin, the hardener, the filler, and the thixotropic agent, the weight ratio of the dispersant to the metal hydroxide is 1:40 to 60. Preferably, the weight ratio of the dispersant to the metal hydroxide is 1:45 to 55. More preferably, the weight ratio of the dispersant to the metal hydroxide is 1:48 to 52.

[0032] The present invention further provides an explosion-proof coating, which comprises the above-mentioned coating composition. Preferably, the explosion-proof coating does not contain the dispersant.

[0033] The present invention further provides an explosion-proof coating, whose glass transition temperature is from 20°C to 40°C, such as: 20°C, 22°C, 24°C, 26°C, 28°C, 30°C, 32°C, 34°C, 36°C, 38°C or 40°C.

[0034] In one embodiment, the explosion-proof coating of the present invention is obtained by curing the above-mentioned coating composition. Preferably, the explosion-proof coating of the present invention is obtained by heat-curing the above-mentioned coating composition. More preferably, the temperature of the heat-curing is from 80°C to 105°C, such as: 80°C, 83°C, 86°C, 89°C, 92°C, 95°C, 97°C, 99°C, 101°C, 103°C or 105°C.

[0035] In one embodiment, the average thickness of the explosion-proof coating is from 1 millimeter (mm) to 3 millimeters, such as: 1 millimeter, 1.2 millimeters, 1.5 millimeters, 1.8 millimeters, 2.1 millimeters, 2.4 millimeters, 2.7 millimeters or 3 millimeters. The average thickness refers to the average distance from the bottom surface to the top surface of the explosion-proof coating, and the top surface faces the external environment.

[0036] The present invention further provides a coated varistor, which comprises a varistor, and the varistor is coated with the explosion-proof coating.

[0037] In one embodiment, the varistor voltage of the coated varistor is from 504 volts to 616 volts, but not limited thereto. The varistor voltage is the voltage measured when 1 milliampere (mA) of direct current passes through the coated varistor. Preferably, the varistor voltage of the coated varistor is from 550 volts to 570 volts. The varistor voltage can also be referred to as the nominal voltage.

[0038] In one embodiment, the coated varistor comprises a body and a plurality of leads, and the body is connected to the plurality of leads. Preferably, the body comprises a ceramic sintered body and the explosion-proof coating, the ceramic sintered body is coated with the explosion-proof coating, and the ceramic sintered body is connected to the plurality of leads. More preferably, only a part of any one of the plurality of leads is coated with the explosion-proof coating.

[0039] In one embodiment, the average maximum width of the body is from 4 millimeters (mm) to 21 millimeters, but not limited thereto. For example, the average maximum width of the body is 4 millimeters, 5 millimeters, 7 millimeters, 10 millimeters, 20 millimeters or 21 millimeters. Preferably, the average maximum width of the body is from 13.5 millimeters to 16 millimeters, such as: 13.5 millimeters, 13.8 millimeters, 14.1 millimeters, 14.4 millimeters, 14.7 millimeters, 15 millimeters, 15.3 millimeters, 15.6 millimeters, 15.9 millimeters or 16.0 millimeters. More preferably, the average maximum width of the body is from 13.9 millimeters to 14.1 millimeters.

[0040] In one embodiment, the average thickness of the body is from 3.6 millimeters (mm) to 5.5 millimeters, but not limited thereto. For example, the average thickness of the body is 3.6 millimeters, 3.9 millimeters, 4.2 millimeters, 4,5 millimeters, 4.8 millimeters, 5.2 millimeters or 5.5 millimeters. Preferably, the average thickness of the body is from 4.4 millimeters to 4.7 millimeters.

[0041] In one embodiment, the coated varistor is used for telecommunications or smart meters, but not limited thereto. Preferably, the telecommunications includes a telephone system.

[0042] The present invention further provides an electronic product, which includes a mobile phone or a smart meter, and the electronic product includes the coated varistor.

[0043] The coated varistor of the present invention has excellent explosion-proof performance. Therefore, when the circuit suffers from an instantaneous voltage surge, the risk of the coated varistor exploding, sparking and burning can be effectively reduced. In addition, the coating composition of the present invention is in a liquid state. Therefore, a complete explosion-proof coating can be provided on the outer surface of the varistor by means of automated dipping. This not only does not rely on manpower, but also can reduce costs, and can make the finished product have a unified specification to ensure the yield and reliability of the finished product. Description of the Drawings

[0044] Figure 1 It is a photograph of the appearance of Example 1-1.

[0045] Figure 2 It is a dynamic thermomechanical analysis diagram of Example 1-2 and Example 1-4.

[0046] Figure 3A It is a photograph of slight sparking during the explosion-proof performance test of Comparative Example 1-3; and

[0047] Figure 3B It is a photograph of a large amount of sparking and molten tin spraying during the explosion-proof performance test of Comparative Example 1-2. Detailed implementation manners

[0048] The following provides multiple operation modes to illustrate the implementation manners of the present invention; those skilled in the art can easily understand the advantages and effects achievable by the present invention through the content of this specification, and make various modifications and changes without departing from the spirit of the present invention to implement or apply the content of the present invention.

[0049] I. Explosion-proof performance test

[0050] (I) Examples 1-1 to 1-4 and Comparative Examples 1-1 to 1-5

[0051] The purpose of configuring the coating compositions of Examples 1-1 to 1-4 and Comparative Examples 1-1 to 1-5 in the present invention is to understand whether the explosion-proof coatings obtained by curing the coating compositions of each group have explosion-proof effects, as described below:

[0052] 1. Formulation:

[0053] The resins, hardeners, fillers, and thixotropic agents in each of Examples 1-1 to 1-4 and Comparative Examples 1-1 to 1-5 adopt the same components, but the weight ratios of the formulations of each group are different, as shown in Table 1; among them, the total weight of the resin, hardener, filler, and thixotropic agent is 100 parts by weight.

[0054] The resin in each group adopts a polyurethane-modified epoxy resin (brand: Nan Ya; specification: NPER-133L, viscosity at 25°C is 10,000 cP to 16,000 cP), the hardener adopts polyetheramine (trade name: D-400 Polyetheramine, viscosity at 25°C is 22 cSt), the filler adopts aluminum hydroxide (D 50 is 15 microns to 20 microns), and the thixotropic agent adopts flaky silicate D 50 is 30 microns; among them, the epoxy equivalent of the polyurethane-modified epoxy resin is 217.5 g / equivalent, and the active hydrogen equivalent of the polyetheramine is 115 g / equivalent.

[0055] Furthermore, each group additionally adds a phosphate ester as a dispersant, and the weight ratio of the addition amount of the dispersant to the filler content is 1:50. Finally, since the resin is in a liquid state, the present invention does not need to additionally add other solvents such as water.

[0056] Table 1: Components and ratios of each group (unit: part by weight)

[0057]

[0058] 2. Manufacturing Method: After preparing a resin, a hardener, a filler, a thixotropic agent, and a dispersant, the resin, the thixotropic agent, and the dispersant are put into a homogenizing mixer according to the formulation ratio shown in Table 1 and mixed evenly to obtain a first mixture; the filler is put into the first mixture and mixed evenly by the homogenizing mixer to obtain a second mixture; and the second mixture is put into a triple roll mill, and the filler in the second mixture is further dispersed by a shearing method to obtain a third mixture for standby.

[0059] Before a varistor is to be coated to form an explosion-proof coating, the hardener is added to the third mixture and stirred evenly to obtain an explosion-proof coating material. After pouring the explosion-proof coating material into a jig, the varistor is slowly and completely immersed in the explosion-proof coating material in a vertically downward direction and held for one minute and then taken out, and then moved to an oven for curing at 100 °C to obtain a finished product, that is, a coated varistor with an explosion-proof coating; where Figure 1 is the finished product of Example 1-1, that is, a coated varistor with a single-layer explosion-proof coating, and it has a body and two leads, and the body is connected to the two leads. In addition, the varistors of the present invention are manufactured in batches, the average maximum width of the body is 14 millimeters (mm), the average thickness of the body is 4.55 millimeters, and the average thickness of the explosion-proof coating is 1.5 millimeters (mm). Finally, the specifications of each finished product are: the varistor voltage is 560 volts (V).

[0060] 3. Testing:

[0061] 3-1. Evaluation of Coating Processability:

[0062] Observing the appearance of the finished product, those with good formability of the explosion-proof coating are marked as O, those with poor formability of the explosion-proof coating, for example: the appearance of the explosion-proof coating has bubbles, or distorted conditions such as pointed tips or skewness are marked as X, and those where the explosion-proof coating cannot be formed are marked as N / A; among them, those where the explosion-proof coating cannot be formed are exempt from the explosion-proof performance test.

[0063] 3-2. Explosion-Proof Performance Test: A 5-ohm resistor and a 5-ampere current fuse are connected in series to the finished product, and an AC voltage of 560 V * 1.5 = 840 V is applied across the two ends of the circuit to observe whether the finished product shows phenomena such as explosion, spark, or combustion, and the description is as follows:

[0064] (1) Explosion: Those without damage to the explosion-proof coating in the finished product are marked as O; if the explosion-proof coating in the finished product shows damage, cracking, or explosion, it is marked as X.

[0065] (2) Spark: Those without sparks appearing in the finished product during the test are marked as O; if slight sparks appear in the finished product during the test (such as Figure 3AThose shown as ( ) are marked as Δ; if a large amount of sparks or molten tin spouts out during the testing of the finished product (as shown in Figure 3B ), it is marked as X.

[0066] (3) Combustion: If there is no combustion or flame in the finished product during the testing process, it is marked as O; if there is a slight flame in the finished product during the testing process: the flame extinguishes itself within less than or equal to 1 second, it is marked as Δ; if there is a combustion phenomenon in the finished product during the testing process: the flame duration is greater than 1 second, it is marked as X.

[0067] The test results of each group are shown in Table 2.

[0068] Table 2: Test results of formability and explosion-proof performance of each group

[0069] Group Formability Bursting Spark Combustion Comparative Example 1-1 O X X X Comparative Example 1-2 O X X X Comparative Example 1-3 O X Δ Δ Example 1-1 O O O O Example 1-2 O O O O Example 1-3 O O O O Example 1-4 O O O O Comparative Example 1-4 X O O O Comparative Example 1-5 N / A -- -- --

[0070] As can be seen from Table 2, Examples 1-1 to 1-4 all have excellent formability and explosion-proof performance test results. Therefore, when the formula of the coating composition is based on a total weight of 100 parts by weight of the resin (polyurethane-modified epoxy resin), the hardener (polyetheramine), the filler (aluminum hydroxide), and the thixotropic agent (platelet silicate), the ratios of the resin content to the hardener content in Examples 1-1 to 1-4 are all 49.8 / 26.4 = 43.6 / 23 = 37.3 / 19.7 = 30.9 / 16.4 = 1.9, and the resin content is 30.9 to 49.8 parts by weight, the hardener content is 16.4 to 26.4 parts by weight, the filler content is 20.1 to 50.5 parts by weight, and the thixotropic agent content is 2.2 to 3.7 parts by weight. The explosion-proof coating formed by the coating composition of the present invention can have excellent formability and make the coated varistor with the explosion-proof coating have excellent explosion-proof performance.

[0071] (II) Comparative Examples 2-1 to 2-12

[0072] The purpose of configuring the coating compositions of Comparative Examples 2-1 to 2-12 in the present invention is to understand the influence of the "filler" type on the explosion-proof performance of the finished product, which is described as follows:

[0073] 1. Formula:

[0074] First, the resins, hardeners, and thixotropic agents in Comparative Examples 2-1 to 2-12 all use the same components and are the same as those in Example 1-1. That is, the resin in each group uses polyurethane-modified epoxy resin, the hardener uses polyetheramine, and the thixotropic agent uses platelet silicate.

[0075] Second, the fillers in Comparative Examples 2-1 to 2-12 are described as follows:

[0076] (1) The first group includes Comparative Examples 2-1 to 2-4, and alumina is used as the filler for all in the first group.

[0077] (2) The second group includes Comparative Examples 2-5 to 2-8, and calcium carbonate is used as the filler for all in the second group.

[0078] (3) The third group includes Comparative Examples 2-9 to 2-12, and silicon carbide is used as the filler for all in the third group.

[0079] The D of the said alumina, the said calcium carbonate and the said silicon carbide 50 is all from 15 microns to 20 microns.

[0080] Third, the formulation ratios of Comparative Examples 2-1 to 2-12 are described as follows:

[0081] The formulation ratios of the respective first groups in the first group to the third group are the same, that is, the formulation ratios of Comparative Examples 2-1, 2-5 and 2-9 are the same: the resin is 49.8 parts by weight, the hardener is 26.4 parts by weight, the filler is 20.1 parts by weight, and the thixotropic agent is 3.7 parts by weight. The formulation ratios of the respective second groups in the first group to the third group are the same, and so on, as shown in Table 3; among them, the total weight of the resin, hardener, filler and thixotropic agent is 100 parts by weight.

[0082] Fourth, each group of Comparative Examples 2-1 to 2-12 is the same as Example 1-1, and a phosphate ester is additionally added as a dispersant, and the weight ratio of the addition amount of the dispersant to the filler content is 1:50.

[0083] Table 3: Components and Proportions of Each (Unit: Parts by Weight)

[0084]

[0085] 2. Preparation method: The same as Example 1-1.

[0086] 3. Testing: The testing method is the same as Example 1-1, and the testing results of each group are shown in Table 4.

[0087] Table 4: Testing Results of Formability and Explosion-Proof Performance of Each Group

[0088] Group Formability Bursting Spark Combustion Comparative Example 2-1 O X X X Comparative Example 2-2 O X O X Comparative Example 2-3 O O O X Comparative Example 2-4 O O O X Comparative Example 2-5 O X Δ X Comparative Example 2-6 O O O X Comparative Example 2-7 O O O X Comparative Example 2-8 X O O X Comparative Example 2-9 O X O X Comparative Example 2-10 O X O X Comparative Example 2-11 O O O X Comparative Example 2-12 N / A -- -- --

[0089] As can be seen from Table 4, the formulation ratios of each group from Comparative Example 2-1 to Comparative Example 2-12 fall within the range where the resin, hardener, filler, and thixotropic agent shown in Examples 1-1 to 1-4 of Table 1 can have excellent formability and enable the coated varistor with an explosion-proof coating to have excellent explosion-proof performance. That is, the ratio of the content of the resin to the content of the hardener is 1.9, and the content of the resin is 30.9 parts by weight to 49.8 parts by weight, the content of the hardener is 16.4 parts by weight to 26.4 parts by weight, the content of the filler is 20.1 parts by weight to 50.5 parts by weight, and the content of the thixotropic agent is 2.2 parts by weight to 3.7 parts by weight. However, when the type of the filler is replaced with alumina, calcium carbonate, or silicon carbide, the finished products all catch fire, lacking explosion-proof performance. It can be seen that using "aluminum hydroxide" as the filler can effectively make the explosion-proof coating formed by its coating composition have excellent formability and enable the coated varistor with the explosion-proof coating to have excellent explosion-proof performance, while reducing the risk of the finished product exploding, sparking, and catching fire.

[0090] (III) Examples 3-1 to 3-3 and Comparative Examples 3-1 to 3-6

[0091] The purpose of configuring the filler compositions of Examples 3-1 to 3-3 and Comparative Examples 3-1 to 3-6 of the present invention is to understand the influence of the type of "hardener" on the explosion-proof performance of the finished product, which is described as follows:

[0092] 1. Formulation:

[0093] First, the resins, fillers, and thixotropic agents of Examples 3-1 to 3-3 and Comparative Examples 3-1 to 3-6 all use the same components and are the same as those in Example 1-1. That is, the resin in each group uses a polyurethane-modified epoxy resin, the filler uses aluminum hydroxide, and the thixotropic agent uses flaky silicate.

[0094] Second, the hardeners of Examples 3-1 to 3-3 and Comparative Examples 3-1 to 3-6 are described as follows:

[0095] (1) The first group includes Examples 3-1 to 3-3, and the hardener in the first group all uses polyetheramine, the same as Example 1-1.

[0096] (2) The second group includes Comparative Examples 3-1 to 3-3, and the hardener in the second group all uses ethylenediamine, also known as diethylenetriamine (DETA), purchased from Di Yi Chemical Industry, and the active hydrogen equivalent is about 21 g / equivalent.

[0097] (3) The third group includes Comparative Examples 3-4 to 3-6, and the hardeners in the third group all use polyamide with a specification of HP90, a product name of VastFLXcure-HP90, and an active hydrogen equivalent of approximately 230 g / equivalent.

[0098] Third, the formulation ratios of Examples 3-1 to 3-3 and Comparative Examples 3-1 to 3-6 are described as follows:

[0099] (1) The first group of each of the first to third groups: The hardeners of Example 3-1, Comparative Example 3-1, and Comparative Example 3-4 are all fixed at 20 parts by weight, and the thixotropic agent is fixed at 3 parts by weight.

[0100] (2) The second group of each of the first to third groups: The hardeners of Example 3-2, Comparative Example 3-2, and Comparative Example 3-5 are all fixed at 30 parts by weight, and the thixotropic agent is fixed at 2.8 parts by weight.

[0101] (3) The third group of each of the first to third groups: The hardeners of Example 3-3, Comparative Example 3-3, and Comparative Example 3-6 are all fixed at 40 parts by weight, and the thixotropic agent is fixed at 2.6 parts by weight.

[0102] (4) Since the active hydrogen equivalents of different hardeners are different, the addition amounts of the resins in each group are also set to be determined by the ratio of the total number of reactive functional groups of the resin to the hardener being 1:1; among them, A. The types of hardeners in Examples 3-1 to 3-3 are the same, so the content ratios of the resin to the hardener will be the same, that is, 37.8 / 20 = 56.7 / 30 = 75.5 / 40 = 1.9; B. The types of hardeners in Comparative Examples 3-1 to 3-3 are the same, so the content ratios of the resin to the hardener will be the same, that is, 206.7 / 20 = 310.0 / 30 = 413.3 / 40 = 10.3; and C. The types of hardeners in Comparative Examples 3-4 to 3-6 are the same, so the content ratios of the resin to the hardener will be the same, that is, 18.9 / 20 = 28.3 / 30 = 37.7 / 40 = 0.94, as shown in Table 5.

[0103] (5) 30 parts by weight of filler are fixedly added to each group of Examples 3-1 to 3-3 and Comparative Examples 3-1 to 3-6.

[0104] (6) Each group of Examples 3-1 to 3-3 and Comparative Examples 3-1 to 3-6 is the same as Example 1-1, and a phosphate ester is additionally added as a dispersant, and the weight ratio of the addition amount of the dispersant to the filler content is 1:50, that is, 0.6 parts by weight.

[0105] Table 5: Components and Ratios (Unit: parts by weight)

[0106]

[0107] 2. Preparation method: The preparation method is the same as that of Example 1-1.

[0108] 3. Testing: The testing method is the same as that of Example 1-1, and the test results of each group are shown in Table 6.

[0109] Table 6: Test results of formability and explosion-proof performance of each group

[0110] Group Formability Bursting Spark Combustion Example 3-1 O O O O Example 3-2 O O O O Example 3-3 O O O O Comparative Example 3-1 O X X Δ Comparative Example 3-2 O X X Δ Comparative Example 3-3 O X X Δ Comparative Example 3-4 O X X O Comparative Example 3-5 O X X O Comparative Example 3-6 O X X O

[0111] As can be seen from Table 6, even though the total number ratio of reactive functional groups of the resin and hardener in Comparative Examples 3-1 to 3-6 is the same as that in Examples 3-1 to 3-3, and a ratio of about 1:1 is used, and it should also have good formability and curing effect, the finished products in Comparative Examples 3-1 to 3-6 still show cracking, sparking or burning. It can be seen that compared with ethylenediamine and polyamide, using "polyetheramine" as the hardener can more effectively make the explosion-proof coating formed by its coating composition have excellent formability, and make the coated varistor with the explosion-proof coating have excellent explosion-proof performance, thereby reducing the risk of cracking, sparking and burning of the finished product.

[0112] Furthermore, when converted based on the total weight of the resin, hardener, filler and thixotropic agent being 100 parts by weight, the contents of the resin, hardener, filler and thixotropic agent in Examples 3-1 to 3-3 are shown in Table 7.

[0113] Table 7: Each component and ratio (unit: part by weight)

[0114]

[0115] As can be seen from Table 7, first, regarding the content of the resin (polyurethane-modified epoxy resin), compared with the maximum content of 49.8 parts by weight shown in Table 1, the maximum feasible content of the polyurethane-modified epoxy resin can actually be increased to 51 parts by weight. Therefore, the feasible content range of the polyurethane-modified epoxy resin is 30.9 parts by weight to 51 parts by weight.

[0116] Second, regarding the content of the hardener (polyetheramine), compared with the maximum content of 26.4 parts by weight shown in Table 1, the maximum feasible content of the polyetheramine can actually be increased to 27 parts by weight. Therefore, the feasible content range of the polyetheramine is 16.4 parts by weight to 27 parts by weight.

[0117] Third, regarding the content of the filler (aluminum hydroxide), the feasible content range of the aluminum hydroxide remains 20.1 parts by weight to 50.5 parts by weight.

[0118] Fourth, regarding the part about the thixotropic agent content, compared with the lowest content of 2.2 parts by weight shown in Table 1, the maximum feasible content of the thixotropic agent can actually be reduced to 1.75 parts by weight. Therefore, the feasible content range of the thixotropic agent is from 1.75 parts by weight to 3.7 parts by weight.

[0119] (4) Comparative Example 4-1

[0120] The purpose of configuring Comparative Example 4-1 in the present invention is to understand the influence of the type of "resin" on the explosion-proof performance of the finished product, as described below:

[0121] 1. Formulation:

[0122] First, the types of components of the hardener, filler, and thixotropic agent in Comparative Example 4-1 are the same as those in Example 1-1. That is, the hardener used in each group is polyetheramine, the filler used in each group is aluminum hydroxide, and the thixotropic agent used in each group is flaky silicate.

[0123] Second, the resin in Comparative Example 4-1 is a polyurethane-epoxy resin block copolymer obtained by physically melting and mixing 65 parts by weight of "epoxy resin" and 35 parts by weight of "polyurethane", which is different from the "polyurethane-modified epoxy resin" used in the resin of Example 1-1, which is a chemical modification.

[0124] Third, with the addition amount of the resin in a ratio of the total number of reactive functional groups of the resin to the hardener of 1:1, the content of the resin (polyurethane-epoxy resin block copolymer) in Comparative Example 4-1 is 39.24 parts by weight, and the content of the hardener is 30.1 parts by weight. In addition, the content of the filler in Comparative Example 4-1 is 30.1 parts by weight, and the content of the thixotropic agent is 0.56 parts by weight. Finally, the addition amount of the dispersant is in a weight ratio of 1:50 to the filler content, that is, the addition amount of the dispersant in Comparative Example 4-1 is 0.6 parts by weight.

[0125] 2. Manufacturing method: The manufacturing method is the same as that of Example 1-1.

[0126] 3. Testing: The testing method is the same as that of Example 1-1, and the test results of each group are shown in Table 8.

[0127] Table 8: Test results of formability and explosion-proof performance of Comparative Example 4-1

[0128] Group Formability Bursting Spark Combustion Comparative Example 4-1 O X X O

[0129] As can be seen from Table 8, even though the total number ratio of reactive functional groups between the resin and the hardener in Comparative Example 4-1 is the same as that in Example 1-1, both adopting a ratio of 1:1, and the resins in Comparative Example 4-1 and Example 1-1 both have polyurethane and epoxy resin units, and should also have good formability and curing effect, but the finished products in Comparative Example 4-1 still showed explosion and sparking. It can be seen that compared with the polyurethane-epoxy block polymer, using "polyurethane-modified epoxy resin" for the resin can more effectively make the explosion-proof coating formed by its coating composition have excellent formability, and make the coated varistor with the explosion-proof coating have excellent explosion-proof performance, thereby reducing the risk of explosion, sparking and combustion of the finished product.

[0130] II. Dynamic Thermomechanical Analysis

[0131] (I) Example 1-2 and Example 1-4

[0132] In this experiment, the coating compositions of Example 1-2 and Example 1-4 were further cured into an explosion-proof coating (without varistor) with a thickness of about 1.5 millimeters (mm), and then analyzed using a dynamic mechanical spectrometer (DMS); wherein, the test frequency was set at 10 Hz, the temperature range was set from -80 °C to 100 °C, and the heating rate was 2 °C per minute. The test results: damping coefficient (Tanδ or Tan delta), half-width at half maximum, and glass transition temperature (Tg) are shown in Table 9 and Figure 1 as follows.

[0133] Table 9: Damping coefficient, half-width at half maximum, and glass transition temperature of each group

[0134]

[0135] As can be seen from Table 9, the damping coefficients of the explosion-proof coatings in Example 1-2 and Example 1-4 at temperatures close to room temperature, that is, 25 °C or 29 °C, are 0.82 to 1.03. In addition, even though the glass transition temperatures of Example 1-2 and Example 1-4 are only 28.9 °C to 29 °C, they can still have excellent explosion-proof performance, thereby reducing the risk of explosion, sparking and combustion of the finished product. Therefore, the coating composition of the present invention has an unexpected explosion-proof effect.

[0136] In summary, the coated varistor of the present invention has excellent damping coefficient and explosion-proof performance. Therefore, when the circuit is subjected to instantaneous voltage surges, the risk of the coated varistor exploding, generating sparks and catching fire can be effectively reduced. In addition, the coating composition of the present invention is in a liquid state. Therefore, by using an automated dipping method to provide a complete explosion-proof coating on the outer surface of the varistor, not only does it not rely on manpower, but it can also reduce costs, and it can also make the finished product have a unified specification to ensure the yield and reliability of the finished product.

Claims

1. A coating composition, characterized in that, Comprising: a resin, a hardener, a filler, and a thixotropic agent; wherein, the resin comprises a polyurethane-modified epoxy resin, the hardener comprises a polyetheramine, the filler comprises a metal hydroxide, the thixotropic agent comprises an inorganic thixotropic agent, and based on the total weight of the resin, the hardener, the filler, and the thixotropic agent being 100 parts by weight, the weight ratio of the polyurethane-modified epoxy resin to the polyetheramine is 1.5 to 2.3:1, the content of the metal hydroxide is 15 parts by weight to 55 parts by weight, and the inorganic thixotropic agent is 1.7 parts by weight to 4.16 parts by weight.

2. The coating composition according to claim 1, wherein The content of the polyurethane-modified epoxy resin is 28.1 parts by weight to 55.5 parts by weight, and the content of the polyetheramine is 14.85 parts by weight to 29.5 parts by weight.

3. The coating composition according to claim 1, wherein The content of the polyurethane-modified epoxy resin is 30.6 parts by weight to 51.5 parts by weight, the content of the polyetheramine is 16.2 parts by weight to 27.3 parts by weight, the content of the metal hydroxide is 19.9 parts by weight to 51 parts by weight, and the inorganic thixotropic agent is 1.73 parts by weight to 3.74 parts by weight.

4. The coating composition according to claim 1, wherein, The metal hydroxide comprises any one or a combination of aluminum hydroxide and magnesium hydroxide.

5. The coating composition according to claim 1, characterized in that The inorganic thixotropic agent comprises a silicate.

6. The coating composition according to claim 1, characterized in that, The epoxy equivalent of the polyurethane-modified epoxy resin is 76 g / equivalent to 250 g / equivalent, and the active hydrogen equivalent of the polyetheramine is 40 g / equivalent to 150 g / equivalent.

7. The coating composition according to claim 1, characterized in that, Further comprising a dispersant, and based on the total weight of the resin, the hardener, the filler, and the thixotropic agent being 100 parts by weight, the content of the dispersant is 0.25 parts by weight to 1.375 parts by weight.

8. The coating composition according to claim 7, wherein, The dispersant comprises any one or a combination of a phosphate ester, an alkyl phosphate ester, and an alkyl polyoxyethylene ether phosphate ester.

9. An explosion-proof coating, characterized in that, Comprising the coating composition according to any one of claims 1 to 6.

10. The explosion-proof coating according to claim 9, characterized in that, The average thickness of the explosion-proof coating is 1 mm to 3 mm.

11. The explosion-proof coating according to claim 9, wherein, The glass transition temperature is 20°C to 40°C.

12. A coated varistor, characterized in that, Comprising a varistor, and the varistor is coated with the explosion-proof coating according to any one of claims 9 to 11.

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