TW201802836A - Overcurrent protection component with positive temperature coefficient for increasing bearing voltage of positive temperature coefficient polymer material layer and achieving stable electric characteristics and reliability - Google Patents

Abstract

An overcurrent protection component with positive temperature coefficient comprises a positive temperature coefficient material layer and two electrodes. The positive temperature coefficient material layer contains a polymer matrix and conductive particle filler. The polymer matrix is composed of heterogeneous rheological polymer. The composition of heterogeneous rheological polymer comprises a first polyolefin unit, a second polyolefin unit and a third polyolefin unit. The first polyolefin unit, the second polyolefin unit and the third polyolefin unit are solidified after melt mixing to form the polymer matrix. The first polyolefin unit has a melt flow index between 0.1 g/10 min to 2.5 g/10 min, the second polyolefin unit has a melt flow index between 20 g/10 min to 30 g/10 min, and the third polyolefin unit has a melt flow index less than 0.00001 g/10 min. The overcurrent protection component with positive temperature coefficient according to the present invention possesses excellent electric stability and reliability.

Description

Positive temperature coefficient overcurrent protection element

The invention relates to a positive temperature coefficient overcurrent protection element, in particular to a positive temperature coefficient of a first polyolefin unit, a second polyolefin unit and a third polyolefin unit having different melt flow index ranges. Current protection element.

Since the positive temperature coefficient conductive polymer element has a positive temperature coefficient effect, it can be used as an overcurrent protection element. The positive temperature coefficient overcurrent protection element includes a positive temperature coefficient conductive polymer material layer and positive and negative electrodes formed on two corresponding surfaces of the positive temperature coefficient conductive polymer material layer. The positive temperature coefficient conductive polymer material layer includes a polymer matrix having a crystalline phase region and an amorphous phase region, and a conductive particle filler dispersed in the amorphous phase region of the polymer matrix to form a continuous conductive path. . The positive temperature coefficient effect means that when the temperature of the polymer matrix rises to its melting point, the crystalline phase region starts to melt and a new amorphous phase region is generated. When the amorphous phase region is increased to a certain extent and combined with the existing amorphous phase region, the conductive path of the conductive particle filler will form a discontinuity, resulting in the positive temperature coefficient of the conductive polymer material. The resistance increases rapidly, and a power failure is caused.

The main requirements of positive temperature coefficient overcurrent protection components are to have high positive temperature coefficient effect, high conductivity, and high electrical stability at the same time.

The traditional positive temperature coefficient conductive polymer material layer usually includes a polymer matrix and a conductive carbon powder filler. The polymer matrix has a polymer composition. The polymer composition typically comprises a non-grafted polyolefin having a weight average molecular weight ranging from 50,000 g / mol to 300,000 g / mol [having a weight range between 0.1 g / 10 min to 10 g at 190 ° C and a pressure of 2.16 kg. / 10 min melt flow index (MFI)] and optionally a grafted polyolefin (having a weight average molecular weight ranging from 50,000 g / mol to 200,000 g / mol (with a temperature of 190 ° C and 2.16 kg) Melt flow index between 0.5 g / 10 min and 10 g / 10 min under pressure). The main function of the grafted polyolefin is to enhance the adhesion between the positive temperature coefficient conductive polymer material layer and the electrode.

Since the withstand voltage of the element is reduced by the conductivity of the conductive toner filler, the current protection element that requires higher conductivity and needs to withstand high voltage is not suitable for the conductive toner filler. In terms of increasing the withstand voltage, although the withstand voltage of the positive temperature coefficient conductive polymer material layer can be increased by adding non-conductive particulate fillers (such as inorganic compounds), the conductivity cannot be improved, and it cannot be used where needed. Higher operating current devices.

Therefore, an object of the present invention is to provide a positive temperature coefficient overcurrent protection element, which can improve the withstand voltage of a positive temperature coefficient polymer material layer and stabilize electrical characteristics and reliability.

Therefore, the positive temperature coefficient overcurrent protection element of the present invention includes a positive temperature coefficient material layer and two electrodes provided on the positive temperature coefficient material layer. The positive temperature coefficient material layer includes a polymer matrix and a conductive particle filler uniformly dispersed in the polymer matrix. The polymer matrix has a hetero-phase rheological polymer composition. The hetero-phase rheological polymer composition includes a first polyolefin unit, a second polyolefin unit, and a third polyolefin unit. The first polyolefin unit includes a non-grafted polyolefin. The first polyolefin unit, the second polyolefin unit, and the third polyolefin are co-melted and kneaded to form the polymer matrix. The first polyolefin unit has a melt flow index between 0.1 g / 10 min and 2.5 g / 10 min at 190 ° C and a pressure of 2.16 kg; the second polyolefin unit has a melt flow index at 190 ° C and a pressure of 2.16 kg A melt flow index between 20 g / 10 min and 30 g / 10 min; the third polyolefin unit has a melt flow index of less than 0.00001 g / 10 min at 190 ° C and a pressure of 2.16 kg. The first polyolefin unit accounts for 2.5-75 wt% of the composition weight of the heterophasic rheological polymer; the second polyolefin unit accounts for 12.5-75 wt% of the composition weight of the heterophasic rheological polymer; and the third polyolefin 12.5-60 wt% of the composition weight of the heterophasic rheological polymer.

The effect of the present invention is that the heterophasic rheological polymer composition includes a second polyolefin unit and a third polyolefin unit in a specific melt flow index range. After co-melting and kneading with the first polyolefin unit, it can be formed into A polymer matrix with high voltage resistance and high voltage reliability, and can improve the electrical stability and reliability of the positive temperature coefficient overcurrent protection element of the present invention.

The following will describe the content of the present invention in detail:

Preferably, the first polyolefin unit has a weight average molecular weight between 50,000 g / mol and 300,000 g / mol.

Preferably, the second polyolefin unit has a weight average molecular weight between 10,000 g / mol and 49,000 g / mol.

Preferably, the third polyolefin unit has a weight average molecular weight of not less than 5,000,000 g / mol. More preferably, the third polyolefin unit has a weight average molecular weight between 5,000,000 g / mol and 10,500,000 g / mol.

Preferably, the first polyolefin unit further comprises a grafted polyolefin.

Preferably, the conductive particle filler is carbon black.

Preferably, the conductive particle filler accounts for 40-60 wt% of the weight of the positive temperature coefficient material layer.

Preferably, the conductive particle filler has a particle diameter of 40-100 nm, a DBP oil absorption of 60-120 cc / 100 g, and an organic volatile component of 0.2-2.0 wt%.

Preferably, the non-grafted polyolefin, the second polyolefin unit and the third polyolefin unit are polyethylene (PE). More preferably, the non-grafted polyolefin, the second polyolefin unit and the third polyolefin unit are high-density polyethylene (HDPE), and the graft-type polyolefin is a carboxylic anhydride-grafted high-density polyethylene.

Before the present invention is described in detail, it should be noted that in the following description, similar elements are represented by the same numbers.

The present invention will be further described with reference to the following examples, but it should be understood that these examples are for illustrative purposes only and should not be construed as limiting the implementation of the present invention.

Referring to FIG. 1, an embodiment of the positive temperature coefficient overcurrent protection element of the present invention includes: a positive temperature coefficient material layer 2 having a volume resistivity greater than zero and less than 0.3 Ω-cm; and two Each electrode 3 is provided on the positive temperature coefficient material layer 2. The positive temperature coefficient material layer 2 includes a polymer matrix 21 and a conductive particle filler 22 uniformly dispersed in the polymer matrix 21.

In a specific embodiment of the present invention, the polymer matrix 21 has a heterogeneous rheological polymer composition. The heterogeneous rheological polymer composition refers to a polymer composition including a polyolefin having a significant difference in melt flow index. The denatured polymer composition includes at least one melt-extrudable first polyolefin unit, a meltable second polyolefin unit, and a meltable third polyolefin unit. The first polyolefin unit includes a non-grafted polyolefin and a grafted polyolefin. The main function of the grafted polyolefin is to enhance the adhesion between the positive temperature coefficient material layer 2 and the two electrodes 3. The first polyolefin unit, the second polyolefin unit and the third polyolefin unit are co-melted, kneaded and solidified to form the polymer matrix 21. The first polyolefin unit has a melt flow index between 0.1 g / 10 min and 2.5 g / 10 min at 190 ° C and a pressure of 2.16 kg; the second polyolefin unit has a melt flow index at 190 ° C and a pressure of 2.16 kg A melt flow index between 20 g / 10 min and 30 g / 10 min; the third polyolefin unit has a melt flow index of less than 0.00001 g / 10 min at 190 ° C and a pressure of 2.16 kg. The first polyolefin unit accounts for 2.5-75 wt% of the composition weight of the heterophasic rheological polymer; the second polyolefin unit accounts for 12.5-75 wt% of the composition weight of the heterophasic rheological polymer; and the third polyolefin 12.5-60 wt% of the composition weight of the heterophasic rheological polymer.

In a specific embodiment of the present invention, the conductive particle filler 22 is carbon black, with an average particle diameter of 82 nm, a DBP oil absorption of 75 cc / 100 g, and an organic volatile content of 1.0 wt%. The conductive particle filler accounts for 40-60 wt% of the weight of the positive temperature coefficient material layer.

< Examples 1 (E1) ＞

High-density polyethylene (purchased from Formosa plastic Corp., HDPE9007) with a weight average molecular weight of 120,000 g / mol was used as the high-density polyethylene for the non-grafted polyolefin (7.875 g). 0.8 g / 10 min), 7.875 g of unsaturated carboxylic acid grafted high density polyethylene (purchased from Dupont, commercial model MB100D, weight average molecular weight 80,000 g / mol, 190 g) as the grafted polyolefin The MFI under the pressure of 2.16 kg is about 2.0 g / 10 min), and 2.625 g is used as the second polyolefin unit of high density polyethylene (purchased from Formosa plastic Corp., product model is HDPE7200, and the weight average molecular weight is 40,000). g / mol, MFI at 190 ° C and 2.16 kg pressure is about 22.0 g / 10 min), 2.625 g is used as the third polyolefin unit of high density polyethylene (purchased from Ticona, product model is GUR4170, weight average Molecular weight of 10,500,000 g / mol, MFI under 190 ° C and pressure of 2.16 kg is less than 0.00001 g / 10 min (approximately 0.0000001 g / 10min), and 29 g of carbon black as a conductive particle filler (purchased from Columbian Chemicals Company, model Raven 430UB, average particle size 82 nm DBP oil absorption of 75 cc / 100 g, volatile organic content of 1.0 wt%, the electric conductivity of ^{2.86 × 10 4 m -1 Ω -1} ) was added to the kneader and kneaded a Brabender. The mixing temperature is 200 ° C; the stirring speed is 50 rpm; the pressing weight is 5 kg; and the mixing time is 10 minutes. The mixture obtained after the kneading is placed in a mold, and then the sample of the mixture is hot-pressed with a hot press at a hot-pressing temperature of 200 ° C, a hot-pressing time of 4 minutes, and a hot-pressing pressure of 80 kg / cm ² . The kneaded sample was hot-pressed into a sheet with a thickness of 0.35 mm. After that, a piece of nickel-plated copper foil (as an electrode) was pasted on each side of the sheet, and then hot-pressed under the same hot-pressing conditions to form a sandwich structure with a thickness of 0.42 mm. The sandwich structure was punched into 8 mm × 8 mm. Wafer samples.

【表2】

表2中的「NA」表示無法進行測試。As shown in Table 1, the positive temperature coefficient material layer 2 of Example 1 consists of 31.5 wt% of the first polyolefin unit (the weight ratio of the non-grafted polyolefin to the grafted polyolefin is 1: 1), 5.25 wt. A second polyolefin unit, a 5.25 wt% third polyolefin unit, and a 58 wt% conductive particle filler. The heterophasic rheological polymer composition is composed of 75 wt% first polyolefin unit, 12.5 wt% second polyolefin unit, and 12.5 wt% third polyolefin unit. The resistance value and volume resistivity of the sample prepared in Example 1 were measured, and the results are shown in Table 2.

【Table 2】

"NA" in Table 2 indicates that the test cannot be performed.

< Examples 2-7 (E2-E7) ＞

The procedures and conditions for preparing the samples of Examples 2-7 are different from those of Example 1 in that the material ratios are different (as shown in Table 1). Table 2 shows the resistance value and volume resistivity of the samples prepared in Examples 2-7.

< Examples 8-10 (E8-E10) ＞

The procedures and conditions for preparing the samples of Examples 8-10 are different from those of Examples 4-6 in that the high-density polyethylene used as the third polyolefin unit is a commercial model GUR4120 (purchased from Ticona, and the commercial model is GUR4120). , The weight average molecular weight is 5,000,000 g / mol, and the MFI at 190 ° C and 2.16 kg pressure is less than 0.00001 g / 10 min (approximately 0.000001 g / 10min) instead of GUR4170 of Example 4-6 (as shown in Table 1) . Table 2 shows the resistance value and volume resistivity of the samples prepared in Examples 8-10.

< Comparative example 1 (CE1) ＞

The preparation procedure and conditions of the sample of Comparative Example 1 are different from those of Example 1 in that Comparative Example 1 does not add the second polyolefin unit and the third polyolefin unit and the material ratio is different (as shown in Table 1). 1 The resistance value and volume resistivity of the prepared sample are shown in Table 2.

< Comparative example 2-4 (CE2-CE4) ＞

The procedure and conditions for preparing the samples of Comparative Example 2-4 are different from those of Example 1 in that Comparative Example 2-4 does not add the third polyolefin unit and the material ratio is different (as shown in Table 1). The resistance value and volume resistivity of the sample obtained in Table 4 are shown in Table 2.

< Comparative example 5-7 (CE5-CE7) ＞

The procedures and conditions for preparing the samples of Comparative Examples 5-7 are different from those of Example 1 in that Comparative Example 5-7 does not add the second polyolefin unit and has a different material ratio (as shown in Table 1). The material formula of Comparative Example 7 cannot be formed into a sample after being mixed in a kneader, so subsequent electrical functional tests cannot be performed. The resistance value and volume resistivity of the samples prepared in Comparative Examples 5-6 are shown in Table 2.

< Comparative example 8-9 (CE8-CE9) ＞

The procedures and conditions for preparing the samples of Comparative Examples 8-9 are different from those of Example 1 in that the material ratios are different (as shown in Table 1). The material formulas of Comparative Examples 8-9 could not be formed into samples after mixing in the kneader, so subsequent electrical function tests could not be performed.

< Comparative example 10-12 (CE10-CE12) ＞

The preparation procedures and conditions of the samples of Comparative Examples 10-12 are different from those of Examples 4-6 in that the high-density polyethylene used as the third polyolefin unit is a product model GUR4012 (purchased from Ticona, product model GUR4012). , The weight average molecular weight is 1,500,000 g / mol, and the MFI at 190 ° C and a pressure of 2.16 kg is 0.00001 g / 10 min) instead of GUR4170 of Example 4-6 (as shown in Table 1). Table 2 shows the resistance value and volume resistivity of the samples prepared in Comparative Examples 10-12.

< Comparative example 13 (CE13) ＞

The preparation procedure and conditions of the sample of Comparative Example 13 are different from those of Comparative Example 6 in that the high-density polyethylene used as the third polyolefin unit is a commercial model GUR4012 instead of GUR4170 of Comparative Example 6 (as shown in Table 1). The resistance value and volume resistivity of the sample prepared in Comparative Example 13 are shown in Table 2.

Electrical function test

Resistance vs. temperature test (Resistance vs. Temperature test, RT test)

The resistance versus temperature test was performed on the samples prepared in Example 1-10 and Comparative Examples 1-6 and 10-13 respectively: The samples were placed in a hot air oven and heated from 25 ° C to 185 ° C at a heating rate of 2 ° C / min. The samples were electrically connected to a micro-ohmmeter (not energized) to collect resistance and temperature data. Each example and each comparative example were tested with 10 samples, and the resistance values at different temperatures were recorded. The results are shown in Table 2.

The results in Table 2 show that the average value of the 140 ° C resistance value (R140) of Example 1 is 1002.58 Ω; while the average value of the 140 ° C resistance value (R140) of Comparative Example 1 is only 553.8 Ω, which is significantly smaller than that of Example 1. 140 The higher the ℃ resistance value (R140) is, the greater the rated voltage that the positive temperature coefficient overcurrent protection element can withstand. The 140 ° C resistance value (R140) of Example 1-10 is significantly larger than the 140 ° C resistance value (R140) of Comparative Examples 1-6 and 10-13, which is about 2 times.

Crash test (Breakdown test)

Crash tests were performed on the samples prepared in Examples 1-10 and Comparative Examples 1-6 and 10-13: 32 Vdc and 100 A were applied for 60 seconds to conduct the test. Each example and each comparative example were tested for 10 For each sample, the pass rate of the number that did not burn down after the test was recorded. The results are shown in Table 2.

The results in Table 2 show that the crash test pass rates of Examples 1-10 were all 100%; the crash test pass rate of Comparative Example 1 (excluding the second polyolefin unit and the third polyolefin unit) was 0%; The pass rate of the crash test of Example 2-4 (excluding the third polyolefin unit) is 0-20%; the pass rate of the crash test of Comparative Examples 5-6 and 13 (excluding the second polyolefin unit) is 20% ; The crash test pass rate of Comparative Example 10-12 (the third polyolefin unit is GUR4012) was only 20-30%, showing that Comparative Examples 1-6 and 10-13 could not reach the 100% pass rate.

The results of the crash test (32 Vdc) show that only formulas containing the second and third polyolefin units and the MFI of the third polyolefin unit are less than 0.00001 g / 10 min at 190 ° C and 2.16 kg pressure. The obtained sample has excellent performance. It is presumed that the addition of the second polyolefin unit and the third polyolefin unit will produce a melt flow phenomenon at the mixing temperature (200 ° C), and the molecular chains between the first polyolefin unit and the first polyolefin unit will fuse with each other to form a stable uniformity. Therefore, the structural strength of the polymer matrix can be improved, and the electrical stability of the positive temperature coefficient overcurrent protection element can be improved.

Endurance test (Endurance test)

及在循環測試後樣品不燒燬的個數通過率，結果如表2所示。Endurance tests were performed on the samples prepared in Examples 1-10 and Comparative Examples 1-6 and 10-13: 7200 cycles were performed at 32 Vdc, 10 A for 60 seconds and 60 seconds after power off. Ten samples were tested for each example and each comparative example, and the resistance change rate of the resistance (Rf) after the test and the resistance (Ri) before the test were recorded.

And the pass rate of the number of samples that did not burn down after the cyclic test, the results are shown in Table 2.

The results in Table 2 show that Comparative Examples 1 and 4 were unable to measure the resistance change rate because the samples were completely burned during the test. The durability test pass rate and resistance change rate of Examples 1-10 were significantly better than those of Comparative Examples 2-3, 5-6 and 10-13 indicate that Examples 1-10 have better electrical durability at 32 Vdc.

Thermal runaway test (Thermal runaway test)

The thermal runaway test was performed on the samples prepared in Example 1-10 and Comparative Examples 1-6 and 10-13: the test was started at 32 Vdc (100 A) at an ambient temperature of 23 ° C, and stepwise at intervals of 2 minutes Rise 3.2 Vdc, increase the voltage from 32 Vdc to 64 Vdc (stop once the component is burned out), test 5 samples for each example and each comparative example, and record the maximum breakdown voltage that the test can withstand (maximum withstand voltage ), The results are shown in Table 2.

The results in Table 2 show that Examples 1-10 did not burn down until the voltage was raised to 64 Vdc, which was significantly better than the maximum withstand voltages 32-35.2 Vdc of Comparative Examples 1-6 and 10-13, indicating that Examples 1-10 had Good voltage resistance.

In summary, the positive temperature coefficient overcurrent protection element of the present invention uses the heterophasic rheological polymer to form a second polyolefin unit and a third polyolefin unit including a specific melt flow index range. After co-melting and mixing, it solidifies to form a polymer matrix with high voltage resistance and high voltage reliability, and thereby improves the electrical stability and reliability of the positive temperature coefficient overcurrent protection element, so it can indeed achieve the purpose of cost invention. .

However, the above are only examples of the present invention. When the scope of implementation of the present invention cannot be limited in this way, any simple equivalent changes and modifications made in accordance with the scope of the patent application and the content of the patent specification of the present invention are still Within the scope of the invention patent.

2‧‧‧Positive temperature coefficient material layer
21‧‧‧ polymer matrix
22‧‧‧ conductive particle filler
3‧‧‧ electrode

Other features and effects of the present invention will be clearly presented in the embodiments with reference to the drawings, in which: [FIG. 1] is a schematic diagram illustrating the structure of a positive temperature coefficient overcurrent protection element according to an embodiment of the present invention.

2‧‧‧Positive temperature coefficient material layer

21‧‧‧ polymer matrix

22‧‧‧ conductive particle filler

3‧‧‧ electrode

Claims (11)

A positive temperature coefficient overcurrent protection element includes: a positive temperature coefficient material layer; and two electrodes provided on the positive temperature coefficient material layer; the positive temperature coefficient material layer includes a polymer matrix and a uniform dispersion in the Filler of conductive particles in a polymer matrix; the polymer matrix has a heterophasic rheological polymer composition, the heterophasic rheological polymer composition includes a first polyolefin unit, a second polyolefin unit and a third polymer Olefin unit, the first polyolefin unit includes an ungrafted polyolefin, the first polyolefin unit, the second polyolefin unit and the third polyolefin are co-melted and kneaded to form the polymer matrix The first polyolefin unit has a melt flow index between 0.1 g / 10 min and 2.5 g / 10 min at 190 ° C and a pressure of 2.16 kg; the second polyolefin unit has a melt flow index at 190 ° C and a pressure of 2.16 kg A melt flow index between 20 g / 10 min and 30 g / 10 min; the third polyolefin unit has a melt flow index of less than 0.00001 g / 10 min at 190 ° C and a pressure of 2.16 kg; the first polymer Olefin units account for this heterogeneous flow 2.5-75 wt% of the composition weight of the denatured polymer; the second polyolefin unit accounts for 12.5-75 wt% of the composition weight of the heterophasic rheological polymer; and the third polyolefin accounts for 12.5-60 wt%. The positive temperature coefficient overcurrent protection device according to claim 1, wherein the first polyolefin unit has a weight average molecular weight between 50,000 g / mol and 300,000 g / mol. The positive temperature coefficient overcurrent protection device according to claim 2, wherein the second polyolefin unit has a weight average molecular weight between 10,000 g / mol and 49,000 g / mol. The positive temperature coefficient overcurrent protection element according to claim 2, wherein the third polyolefin unit has a weight average molecular weight of not less than 5,000,000 g / mol. The positive temperature coefficient overcurrent protection device according to claim 4, wherein the third polyolefin unit has a weight average molecular weight between 5,000,000 g / mol and 10,500,000 g / mol. The positive temperature coefficient overcurrent protection device according to claim 1, wherein the first polyolefin unit further comprises a grafted polyolefin. The positive temperature coefficient overcurrent protection device according to claim 1, wherein the conductive particle filler is carbon black. The positive temperature coefficient overcurrent protection element according to claim 1, wherein the conductive particle filler accounts for 40-60 wt% of the weight of the positive temperature coefficient material layer. The positive temperature coefficient overcurrent protection element according to claim 7, wherein the conductive particle filler has a particle diameter of 40-100 nm, a DBP oil absorption of 60-120 cc / 100 g, and an organic volatile content of 0.2- 2.0 wt%. The positive temperature coefficient overcurrent protection element according to claim 1, wherein the non-grafted polyolefin, the second polyolefin unit, and the third polyolefin unit are polyethylene. The positive temperature coefficient overcurrent protection device according to claim 6, wherein the non-grafted polyolefin, the second polyolefin unit, and the third polyolefin unit are high-density polyethylene, and the grafted polyolefin is Carboxylic anhydride grafted high density polyethylene.