Epoxy Resin Composition

Abstract

A composition comprising (a) a cationically polymerisable epoxy resin, (b) an initiator for the cationic polymerisation, (c) a microparticle filler, and (d) a nanoparticle filler can be used for the production of thermally stable insulating material for electrical and electronic components.

Claims

1. A method for insulating electrical or electronic components comprising the steps (i) applying a curable composition to one or more electrical or electronic components; and (ii) curing the curable composition at a temperature greater than 60° C., wherein the curable composition comprises: (a) 10-40% by weight, based on the total amount of components (a)+(b)+(c)+(d), of a cationically polymerisable cycloaliphatic epoxy resin, (b) an initiator for the cationic polymerisation, (c) a microparticle filler comprising (i) at least one amorphous silica that has been surface treated with a chlorosilane and (ii) at least one of an angular amorphous silica, an angular aluminium oxide or an angular semi-metal nitride, carbide or hydroxide, and (d) a silica nanoparticle, wherein component (b) is a mixture comprising: (b1) a quaternary ammonium salt with an aromatic heterocyclic cation having one or two nitrogen atoms and a non-nucleophilic anion selected from BF.sub.4.sup.−, PF.sub.6.sup.−, SbF.sub.6.sup.−, SbF.sub.5OH.sup.−, BX.sub.pY.sub.q.sup.− or CF.sub.3(CF.sub.2).sub.mSO.sub.3.sup.−, wherein p and q are 0, 1, 2, 3 or 4, provided that p+q=4, X denotes halogen or hydroxyl, Y represents phenyl or naphthyl which are unsubstituted or substituted by fluoro, trifluoromethyl, trifluoromethoxy, nitro or cyano, and m is 0 or an integer from 1 to 17; and (b2) a 1,2-ethanediol substituted by four aromatic radicals.

2. The method according to claim 1, wherein the component (b2) is a compound of formula (5) ##STR00005## wherein R.sub.8, R.sub.9, R.sub.10 and R.sub.11 independently of the other are phenyl that is unsubstituted or substituted by C.sub.1-C.sub.12 alkyl, C.sub.1-C.sub.12 alkoxy, C.sub.7-C.sub.36 aralkyl, C.sub.6-C.sub.36 aryl, C.sub.3-C.sub.15 alkoxyalkyl, C.sub.1-C.sub.12 alkylthio, C.sub.1-C.sub.12 alkylcarbonyl, halogen, nitro or cyano, and R.sub.12 and R.sub.13 independently of the other are hydrogen or C.sub.1-C.sub.12 alkyl.

3. The method according to claim 1, wherein the total amount of microparticle filler (c) and nanoparticle filler (d) of the curable composition is 60 to 90% by weight, based on the total amount of components (a), (b), (c), and (d).

4. The method according to claim 1, wherein the amount of nanoparticle filler (d) in the curable composition is 2 to 20% by weight, based on the total amount of components (a), (b), (c), and (d).

5. The method according to claim 1, wherein the one or more electrical or electronic components are selected from printed circuit boards, stators, rotators, bushings, transformers, and/or switchgears.

6. An insulated electrical and electronic component obtained by the method according to claim 1.

7. A method for insulating electrical or electronic components comprising the steps (i) applying a curable composition to one or more electrical or electronic components; and (ii) curing the curable composition at a temperature greater than 60° C., wherein the curable composition comprises: (a) 10-40% by weight, based on the total weight of components (a)+(b)+(c)+(d)+(e), of a cationically polymerisable cycloaliphatic epoxy resin, (b) a curing accelerator selected from tertiary amines, urea derivatives, unsubstituted or substituted imidazoles, and one or more complexes of amines with boron trichloride or boron trifluoride, (c) a microparticle filler comprising (i) at least one amorphous silica that has been surface treated with a chlorosilane and (ii) at least one of an angular amorphous silica, an angular aluminium oxide or an angular semi-metal nitride, carbide or hydroxide, and (d) a silica nanoparticle filler and (e) an initiator for the cationic polymerization comprising: (b1) a quaternary ammonium salt with an aromatic heterocyclic cation having one or two 585 nitrogen atoms and a non-nucleophilic anion selected from BF.sub.4.sup.−, PF.sub.6.sup.−, SbF.sub.6.sup.−, SbF.sub.5OH.sup.−, BX.sub.pY.sub.q.sup.− or CF.sub.3(CF.sub.2).sub.mSO.sub.3.sup.−, wherein p and q are 0, 1, 2, 3 or 4, provided that p+q=4, X denotes halogen or hydroxyl, Y represents phenyl or naphthyl which are unsubstituted or substituted by fluoro, trifluoromethyl, trifluoromethoxy, nitro or cyano, and m is 0 or an integer from 1 to 17; and (b2) a 1,2-ethanediol substituted by four aromatic radicals.

8. An insulated electrical and electronic component obtained by the method according to claim 7.

Description

EXAMPLES

[0095] Measurement of Properties:

[0096] Unless otherwise indicated, the viscosity is determined with a Rheomat equipment (type 115, MS DIN 125 D=10/s) at 60° C.

[0097] Tensile strength and elongation at break are determined at 23° C. according to ISO R527 K.sub.IC (critical stress intensity factor) in MPa.Math.√{square root over (m)} and G.sub.IC (specific break energy) in J/m.sup.2 are 390 determined at 23° C. by double torsion experiment (Huntsman-internal method).

[0098] CTE (coefficient of linear thermal expansion) is determined according to DIN 53752

[0099] T.sub.g (glass transition temperature) is determined according to ISO 6721/94

[0100] SCT: Crack index (simulated crack temperature) is calculated based on T.sub.g, G.sub.IC, CTE and elongation at break according to the description given in WO 00/55254.

[0101] List of Used Raw Materials [0102] ARALDITE®CY 179-1: 3,4-epoxycyclohexyl)methyl 3,4-epoxycyclohexanecarboxylate (supplied by Huntsman Advanced Materials (Switzerland) GmbH) [0103] 400 ARALDITE®XB 5992 liquid, low viscous bisphenol A epoxy resin, epoxide number: 4.9-5.1 eq/kg (supplied by Huntsman) [0104] ARALDITE®XB 5993 liquid, pre-accelerated anhydride curing agent. (supplied by Huntsman) [0105] ARADUR® HY 906 anhydride curing agent, mixture of 1-methyl-5-norbornene-2,3-dicarboxylic anhydride and 5-norbornene-2,3-dicarboxylic anhydride (supplied by Huntsman) [0106] ACCELERATOR 1: 1-methylimidazole [0107] INITIATOR 1: N-benzylquinolinium hexafluoroantimonate (supplied by Huntsman) [0108] CO-INITIATOR 1: 1,1,2,2-tetraphenyl-1,2-ethanediol (supplied by Natland Int. Corp.) [0109] NANOPOX® E 601: 60% by weight of 3,4-epoxycyclohexyl)methyl-3,4-epoxycyclohexanecarboxylate and 40% by weight of surface-modified silica nanoparticles (supplied by Evonik) [0110] AEROSIL® R 972: (supplied by Evonik) 415 fumed silica aftertreated with DDS (Dimethyldichlorosilane), [0111] AMOSIL® 510: (supplied by Quarzwerke) fused silica produced from natural amorphous silica by grinding with subsequent air separation; average particle size d.sub.50: 11 μm (supplied by Quarzwerke) [0112] AMOSIL® 520: fused silica produced from natural amorphous silica by grinding with subsequent air separation; average particle size d.sub.50: 21 μm (supplied by Quarzwerke) [0113] BYK W 940 anti-settling additive (supplied by: BYK-Chemie GmbH), [0114] BYK W 995 wetting and dispersing agent, phosphate-containing polyester (supplied by: BYK-Chemie GmbH), [0115] BYK 070: defoaming agent based on silicones and polymers (supplied by: BYK-Chemie GmbH) [0116] SILFOAM@ SH: antifoam agent, (supplied by Wacker) [0117] BAYFERROX® 225 iron oxide pigment (supplied by Lanxess) [0118] TREMIN® 283-600 wollastonite, surface-treated with a epoxysilane, average particle size d.sub.50: 21 μm (supplied by Quarzwerke) [0119] SILAN A-187 γ-glycidyloxypropyltrimethoxysilane (supplied by Momentive)

Example A1

[0120] Initially, 2 master batches containing the ingredients of the initiator are prepared as follows:

[0121] Masterbatch A: 90 g of ARALDITE® CY 179-1 and 10 g of Co-initiator 1 are mixed at 90° C. for 30 min. The resulting clear solution is cooled to room temperature (RT).

[0122] Masterbatch B: 90 g of ARALDITE® CY 179-1 and 10 g of Initiator 1 are mixed at 60° C. for 30 min. The resulting clear solution is cooled to RT.

[0123] 138 g of ARALDITE® CY 179-1, 450 g of NANOPOX® E 601, 34 g of Master batch A, 26 g of Master batch B, 4.2 g of SILFOAM@ SH, 10 g BYK-W 940, 4.2 g BYK 070 and 4.0 g AEROSIL® R 972 are put into an Esco mixer of sufficient size. The content of the mixer is then stirred with a disperser stirrer with 100 rpm while heating up to 50° C.

[0124] Then 435 g of AMOSIL® 510 and 894.6 g of AMOSIL® 520 are added slowly in several portions while mixing at 100 rpm. After 5 min the mixer is stopped and the walls are scratched and the material is put into the mixture. Then the mixture is stirred for another 70 min. under vacuum at 50° C. After 30 min. of mixing the walls are scratched again and the material is put into the mixture.

[0125] To produce 4 mm thick test plates, metal molds were preheated to about 80° C. in an oven. Then the degassed resin is poured in the mold. The mold is then put to an oven at 120° C. for 1 hour. After that the oven temperature is raised to 180° C. for 90 min. Then the mold is taken out of the oven and opened after cooling down to room temperature. The obtained plate is used to cut out test specimens for the K.sub.IC/G.sub.IC tests, for the tensile strength testing, the T.sub.g measurement via DSC and the determination of the CTE according to the standards mentioned above. The results are given in Table 1.

Comparative Example C1

[0126] As described in Example 2 of WO 2010/112272, 100 g of ARALDITE® XB 5992 are mixed with 90 g of ARALDITE XB 5993 and the mixture is heated while slightly stirring with a propeller stirrer to about 60° C. for about 5 minutes. Then the mixer is stopped and 2 g of BAYFERROX® 225 is added and the mixer is started again for about 1 min. Subsequently, while stirring, 51.3 g of TREMIN® 283-600 EST and 290.7 g of AMOSIL® 520 are added in portions and the mixture is heated up to 60° C. under stirring for about 10 minutes. Then the mixer is stopped and the vessel is degassed carefully by applying a vacuum for about 1 minute.

[0127] The mixture is poured into a 140° C. hot steel mold to prepare plates for the determination of the properties (4 mm thickness). The mold is then put to an oven for 30 minutes at 140° C. After thermally curing the mold, the mold is taken out of the oven and the plates are cooled down to ambient temperature (25° C.).

[0128] The results of the tests are summarised in Table 1.

Comparative Example C2

[0129] 1. Epoxy Resin Formulation:

[0130] 950 g NANOPOX® E 601, 3.75 g SILFOAM@ SH, 5.0 g BYK W 955, 6.25 g BYK 070, 12.5 g SILAN A-187 and 22.5 g AEROSIL® R 972 are put to a Esco mixer of sufficient size. The content of the mixer is then heated up 60° C. and stirred with a dissolver stirrer with 300 rpm under vacuum at 60° C. for 3 min. Then the vacuum is broken and 500 g of AMOSIL® 510 and 1000 g of AMOSIL® 520 are added slowly in several portions while mixing at 300 rpm at 60-65° C. under vacuum. After 10 min the mixer is stopped, the vacuum is broken and the walls are scratched and the material is put to the mixture. Then the mixture is stirred another 5 min. under vacuum at 60-65° C. The vacuum is broken and the mixer walls are scratched again. Finally the mixture is stirred for 20 min. under vacuum at 300 rpm at 60-65° C.

[0131] 2. Hardener Formulation:

[0132] 879.8 g ARADUR®HY 906, 7.4 g ACCELERATOR 1, 10 g SLAN A-187 and 10 g of BYK-W 940 are put to an Esco mixer of sufficient size. The content of the mixer is then heated up 50° C. and stirred with a dissolver stirrer with 300 rpm under vacuum at 50° C. for 3 min. Then the vacuum is broken and 1092.8 g of AMOSIL® 510 are added slowly in several portions while mixing at 300 rpm at 50° C. under vacuum. After 10 min the mixer is stopped, the vacuum is broken and the walls are scratched and the material is put to the mixture. Then the mixture is stirred another 5 min. under vacuum at 50-55° C. The vacuum is broken and the mixer walls are scratched again. Finally the mixture was stirred for 20 min. under vacuum at 300 rpm at 55-60° C. 3. Preparation of Resin/Hardener-Mixture and Curing:

[0133] 500 g of resin formulation and 325 g of hardener formulation are put together and heated to about 60° C. while stirring with 100 rpm under vacuum.

[0134] To produce 4 mm thick test plates, metal molds are preheated to about 80° C. in an oven. Then the degassed resin/hardener mixture is poured into the mold. The mold is then put to an oven at 100° C. for one hour, then for 1.5 hours at 140° C. and finally for 1.5 hours at 210° C. Then the mold is taken out of the oven and opened after cooling down to room temperature. The cured plate is subjected to various tests the results of which are given in Table 1.

TABLE-US-00001 TABLE 1 The amounts of the ingredients of Compositions A1, C1 and C2 are given in parts by weight Composition A1 C1 C2 ARALDITE ® 9.60 CY 179-1 ARALDITE ® 18.73 XB 5992 INITIATOR 1 0.13 CO-INITIATOR 1 0.17 ARALDITE ® 16.85 XB 5993 ARADUR ® HY 906 17.33 ACCELERATOR 1 0.15 NANOPOX ® E 601 22.50 23.03 AEROSIL ® R 972 0.20 0.55 AMOSIL ® 510 21.75 33.65 AMOSIL ® 520 44.73 54.44 24.24 TREMIN ® 283-600 9.61 BYK W 940 0.50 0.20 BYK W 995 0.12 BYK 070 0.21 0.15 SILFOAM ® SH 0.21 0.09 SILAN A-187 0.50 BAYFERROX ® 225 0.37 Viscosity at 60° 15 8.6 5 C./Pa .Math. s Curing conditions   1 h/120° C. 30 min/140° C.   1 h/100° C. 1.5 h/180° C. 1.5 h/140° C. 1.5 h/210° C. Tensile strength/MPa 75 86 62.3 Elongation at break/% 0.6 1.1 0.65 K.sub.1C/MPa .Math. √m 2.4 2.4 2.2 G.sub.1C/J/m.sup.2 320 441 362 R42 lable no yes yes CTE/ppm/K 20 25.7 24 T.sub.g/° C. 184 105 205 SCT/° C. −271 −131 −184

DISCUSSION OF TEST RESULTS

[0135] The inventive composition A1 provides a cured product that fulfills all the requirements of a single-component encapsulation system for high temperature stable insulations:

[0136] T.sub.g>180° C., SCT<−200° C., CTE<20 ppm/K, free of R42 label.

[0137] Furthermore, the viscosity of the curable composition is sufficient low for applications as encapsulation system for printed circuit boards.

[0138] The product obtained from Comparative Example C1 has a quite low, but yet insufficient SCT of −131 at a T.sub.g of 105° C. (which is far too low) and a CTE of 25.7 (which is too high). The properties of the cured product according to Comparative Example C2 are satisfactory with respect to T.sub.g and CTE, but completely insufficient with respect to SCT. It is not a solution to the problem because it is R42-labelled, but mainly because the SCT is far too high (−84° C. vs. target of −200° C.). Furthermore, Composition C2 suffers from the classification as hazardous substance (label R42, “respiratory sensitizer”)