Halogen-free flame-retardant metallized film capacitor

Abstract

The present application relates to a kind of halogen-free flame-retardant metallized film capacitor, including aluminum shell, capacitor core in aluminum shell and the resin encapsulation layer for the insulation encapsulation of capacitor core, resin encapsulation layer is made by curing benzoxazine resin glue, the benzoxazine resin glue is made by uniformly mixing 100 mass parts 4,4'-diamino diphenyl methane type benzoxazine, 20~25 mass parts curing agent, 0.5~0.7 mass parts accelerator, 15~20 mass parts filler, 3.5~5 mass parts flame retardant and 100~150 mass parts solvent.The halogen-free flame-retardant metallized film capacitor meets halogen-free requirement, and flame resistance is good, total smoke release is very low, and heat resistance is high.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of film capacitors, and particularly relates to a halogen-free flame-retardant metallized film capacitor. BACKGROUND

[0002] Film capacitor is also called plastic film capacitor. The plastic film is used as dielectric.

[0003] The structure of the existing film capacitor generally comprises a capacitor shell, a capacitor core, and an epoxy resin encapsulation layer for completely wrapping the capacitor core. The epoxy resin encapsulation layer is generally made of epoxy resin adhesive doped with fillers (such as spherical aluminum oxide) and then cured.

[0004] However, the existing epoxy resin has poor flame retardancy and low heat resistance, and generally cannot reach V0 level of flame retardancy (UL94 standard). A large amount of bromine-based flame retardant needs to be added, but the bromine-based flame retardant does not meet the environmental protection requirements. In addition, a large amount of added bromine-based flame retardant will cause poor heat resistance, which is a difficult problem to be solved for large-capacity energy storage capacitors. SUMMARY

[0005] The specific technical solutions of the present application are as follows:

[0006] The halogen-free flame-retardant metallized film capacitor comprises an aluminum shell, a capacitor core located in the aluminum shell, and a resin encapsulation layer for insulating and encapsulating the capacitor core. The resin encapsulation layer is made of a cured benzoxazine resin adhesive. The benzoxazine resin adhesive is made by uniformly mixing benzoxazine resin, curing agent, accelerator, filler, flame retardant, and solvent.

[0007] In an alternative embodiment, the benzoxazine resin adhesive is made by uniformly mixing 100 parts by mass of benzoxazine resin, 20-25 parts by mass of curing agent, 0.5-0.7 parts by mass of accelerator, 15-20 parts by mass of filler, 3.5-5 parts by mass of flame retardant, and 100-150 parts by mass of solvent.

[0008] In an alternative embodiment, the benzoxazine resin is 4,4'-diamino diphenyl methane type benzoxazine, and its structural formula is shown as formula 1:

[0009]

[0010] In an alternative embodiment, the curing agent is one or more of 4,4'-diamino diphenyl sulfone, 4,4'-diamino diphenyl methane, 4,4'-diamino diphenyl ether, and dicyandiamide.

[0011] In an optional embodiment, the accelerator is 2-methylimidazole or 2-phenylimidazole.

[0012] In an optional embodiment, the filler is one or more of magnesium hydroxide, aluminum hydroxide, aluminum oxide, aluminum nitride, silicon dioxide, and silicon powder.

[0013] In an optional embodiment, the solvent is one or more of acetone, butanone, N,N-dimethylformamide, propylene glycol monomethyl ether, toluene, and xylene.

[0014] In an optional embodiment, the flame retardant is aminotrimethylenephosphonic acid or aluminum alkylphosphinate.

[0015] In an optional embodiment, the curing agent is prepared by mixing 4,4'-diaminodiphenyl sulfone and dicyandiamide in a mass ratio of 10:3, and the flame retardant is aminotrimethylenephosphonic acid.

[0016] In the present invention, the halogen-free flame-retardant metallized film capacitor meets the halogen-free requirement, has good flame retardancy, very low total smoke emission, and high heat resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is the trend diagram of x value and total smoke release;

[0018] Figure 2 This is a graph showing the variation trend between the dosage of flame retardant aminotrimethylenephosphonic acid and Tg value;

[0019] Figure 3 This is a physical photo of the halogen-free flame-retardant metallized film capacitor described in Example 1. DETAILED DESCRIPTION

[0020] The present invention will be further explained below with reference to the accompanying drawings and specific embodiments.

[0021] Example 1

[0022] A halogen-free flame-retardant metallized film capacitor comprises an aluminum shell, a capacitor core within the aluminum shell, and a resin encapsulation layer for insulating and encapsulating the capacitor core. The resin encapsulation layer is made by curing a benzoxazine resin adhesive. The benzoxazine resin adhesive is prepared by uniformly mixing 1000g of benzoxazine resin, 200g of a curing agent, 5g of an accelerator, 150g of a filler, 35g of a flame retardant, and 1000g of a solvent.

[0023] The benzoxazine resin is 4,4'-diaminodiphenylmethane type benzoxazine, and its structural formula is as follows:

[0024] As shown in formula 1:

[0025]

[0026] The curing agent is made by mixing 4,4'-diaminodiphenyl sulfone and dicyandiamide in a mass ratio of 10:3. The flame retardant is aminotrimethylenephosphonic acid. The accelerator is 2-methylimidazole. The filler is aluminum oxide. The solvent is propylene glycol monomethyl ether.

[0027] The halogen-free flame-retardant metallized film capacitors described in this example are shown in Figure 3 .

[0028] Example 2

[0029] A halogen-free flame-retardant metallized film capacitor comprises an aluminum shell, a capacitor core within the aluminum shell, and a resin encapsulation layer for insulating and encapsulating the capacitor core. The resin encapsulation layer is made by curing a benzoxazine resin adhesive. The benzoxazine resin adhesive is prepared by uniformly mixing 1000g of benzoxazine resin, 220g of a curing agent, 6g of an accelerator, 160g of a filler, 40g of a flame retardant, and 1200g of a solvent.

[0030] The benzoxazine resin is 4,4'-diaminodiphenylmethane type benzoxazine, and its structural formula is shown in Formula 1.

[0031] The curing agent is made by mixing 4,4'-diaminodiphenyl sulfone and dicyandiamide in a mass ratio of 10:3. The flame retardant is aminotrimethylenephosphonic acid. The accelerator is 2-methylimidazole. The filler is aluminum oxide. The solvent is propylene glycol monomethyl ether.

[0032] Example 3

[0033] A halogen-free flame-retardant metallized film capacitor comprises an aluminum shell, a capacitor core within the aluminum shell, and a resin encapsulation layer for insulating and encapsulating the capacitor core. The resin encapsulation layer is made by curing a benzoxazine resin adhesive. The benzoxazine resin adhesive is prepared by uniformly mixing 1000g of benzoxazine resin, 250g of a curing agent, 7g of an accelerator, 200g of a filler, 50g of a flame retardant, and 1500g of a solvent.

[0034] The benzoxazine resin is 4,4'-diaminodiphenylmethane type benzoxazine, and its structural formula is shown in Formula 1.

[0035] The curing agent is made by mixing 4,4'-diaminodiphenyl sulfone and dicyandiamide in a mass ratio of 10:3. The flame retardant is aminotrimethylenephosphonic acid. The accelerator is 2-methylimidazole. The filler is aluminum oxide. The solvent is propylene glycol monomethyl ether.

[0036] Comparative Example 1

[0037] In this example, the curing agent is 4,4'-diaminodiphenyl sulfone, and the rest is the same as in Example 2.

[0038] Comparative Example 2

[0039] In this example, the curing agent is dicyandiamide, and the rest is the same as in Example 2.

[0040] Comparative Example 3

[0041] In this example, the benzoxazine resin is bisphenol A benzoxazine resin, and the rest is the same as in Example 2.

[0042] Comparative Example 4

[0043] In this example, the benzoxazine resin is a DOPO-type benzoxazine resin, and the rest is the same as in Example 2.

[0044] Comparative Example 5

[0045] In this example, the flame retardant is aluminum alkyl phosphinate, and the rest is the same as in Example 2.

[0046] Comparative Example 6

[0047] In this example, the flame retardant is melamine polyphosphate (CAS No. 15541-60-3), and the rest is the same as in Example 2.

[0048] The test results of the resin encapsulation layer performance in Examples 1 to 3 and Comparative Examples 1 to 6 are shown in Table 1:

[0049] Table 1

[0050] UL94 flame retardant performance Heat resistance Tg(℃) Total smoke release (m 2 )]]> Example 1 V0 210 13.05 Example 2 V0 205 12.98 Example 3 V0 208 13.77 Comparative Example 1 V0 203 28.71 Comparative Example 2 V0 188 30.65 Comparative Example 3 V1 175 / Comparative Example 4 V1 158 / Comparative Example 5 V0 209 25.68 Comparative Example 6 V0 203 33.01

[0051] As can be seen from the above, the use of 4,4'-diaminodiphenylmethane-based benzoxazine has high heat resistance and is suitable for the capacitor industry. Furthermore, the curing agent, 4,4'-diaminodiphenylsulfone combined with dicyandiamide, significantly enhances the flame retardant effect of the flame retardant aminotrimethylenephosphonic acid, particularly its smoke suppression effect.

[0052] Comparative Example 7

[0053] The curing agent is prepared by mixing 4,4'-diaminodiphenyl sulfone and dicyandiamide in a mass ratio of 10:x, and the rest is the same as in Example 2. When x varies in the range of 0.5 to 7, the corresponding total smoke emission change trend is shown in FIG. Figure 1 .Depend on Figure 1 It can be seen that x is preferably 3.

[0054] Comparative Example 8

[0055] In the experiment, it was found that as the amount of flame retardant aminotrimethylenephosphonic acid (ratio of aminotrimethylenephosphonic acid to 4,4'-diaminodiphenylmethane benzoxazine) increased, the flame retardant performance reached the limit (V0, total smoke emission was between 12.5 and 13.8 m 2 No less than 12.5m 2 ), but the higher the amount of flame retardant amino trimethylene phosphonic acid is added, the lower the Tg value will be. The trend of change is shown in Figure 2 .

[0056] Depend on Figure 2 It can be seen that, considering flame retardancy and heat resistance, preferably, the blending amount of the flame retardant aminotrimethylenephosphonic acid is 3.5% to 5%.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A halogen-free flame-retardant metallized film capacitor comprising an aluminum shell, a capacitor core within the aluminum shell, and a resin encapsulation layer for insulating and encapsulating the capacitor core, characterized in that: The resin encapsulation layer is made of a benzoxazine resin adhesive that is cured, and the benzoxazine resin adhesive is made by uniformly mixing a benzoxazine resin, a curing agent, an accelerator, a filler, a flame retardant, and a solvent; The benzoxazine resin is 4,4'-diaminodiphenylmethane type benzoxazine, and its structural formula is shown in Formula 1: Formula 1; The curing agent is prepared by mixing 4,4'-diaminodiphenyl sulfone and dicyandiamide in a mass ratio of 10:3, and the flame retardant is aminotrimethylenephosphonic acid.

2. The halogen-free flame-retardant metallized film capacitor according to claim 1, characterized in that: The benzoxazine resin adhesive is prepared by uniformly mixing 100 parts by mass of benzoxazine resin, 20-25 parts by mass of curing agent, 0.5-0.7 parts by mass of accelerator, 15-20 parts by mass of filler, 3.5-5 parts by mass of flame retardant and 100-150 parts by mass of solvent.

3. The halogen-free flame-retardant metallized film capacitor according to claim 1, characterized in that: The accelerator is 2-methylimidazole or 2-phenylimidazole.

4. The halogen-free flame-retardant metallized film capacitor according to claim 1, characterized in that: The filler is one or more of magnesium hydroxide, aluminum hydroxide, aluminum oxide, aluminum nitride, silicon dioxide, and silicon micropowder.

5. The halogen-free flame-retardant metallized film capacitor according to claim 1, characterized in that: The solvent is one or more of acetone, butanone, N,N-dimethylformamide, propylene glycol monomethyl ether, toluene, and xylene.

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