EP4688940A1

EP4688940A1 - High-voltage resistant polyamide composition

Info

Publication number: EP4688940A1
Application number: EP24718718.0A
Authority: EP
Inventors: Yunfeng Zhao; Lin Chen
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2023-04-03
Filing date: 2024-04-01
Publication date: 2026-02-11
Also published as: JP2026511963A; CN121079351A; WO2024208771A1; KR20250171329A

Abstract

The present invention relates to a polyamide composition comprising (A) from 40% to 80% by weight of a polyamide containing at least one type of monomer units having at least 8 carbon atoms, and (B) from 20% to 60% by weight of a filler in a lamellar shape having a diameter-to-thickness ratio of at least 70, based on the total weight of the polyamide composition, and also use thereof as insulating materials withstanding high electrical stresses.

Description

HIGH-VOLTAGE RESISTANT POLYAMIDE COMPOSITION

FIELD OF INVENTION

The present invention relates to a high-voltage resistant polyamide composition and use thereof as insulating materials withstanding high electrical stresses, particularly as insulating plastic materials in high-voltage transmission and distribution systems.

BACKGROUND OF THE INVENTION

High-voltage transmission and distribution of electricity need insulating materials in almost every application such as circuit breakers, reclosers and transformers. The insulating materials in such an application must be able to withstand high electrical stresses due to the high voltage being applied, and therefore need excellent dielectric features. Ceramics and thermosets such as epoxy resins and silicone rubbers are normally used as insulating materials in many applications. However, thermoplastics have rarely been developed as the insulating materials in high-voltage transmission and distribution applications since the high-voltage resistance of thermoplastics is generally not sufficient.

US6653571 B1 describes a high-voltage electrical insulation material which comprises a polymeric material and an ester compound having fluorinated alkyl end group as a water- repellent additive. The polymeric material of the insulation material as described in the patent includes polyolefins, olefin copolymers, substituted polyolefins, substituted olefin copolymers, particularly ethylene-vinyl acetate copolymers (EVA); linear low-density polyethylene (LLDPE); acrylic rubbers, silicone polymers, epoxy resins, polyurethanes and polyethers. It is described that the electrical insulation material may be used in a great many applications where electrical components are exposed to voltages of above about 1 kV.

In addition to the insufficient high-voltage resistance, the application of some thermoplastics as insulating materials may be hindered by other properties. For example, polyamides, a versatile engineering thermoplastic, were not well developed for high-voltage insulating applications due to their inherent moisture-uptake property.

US20180033519A1 describes a thermoplastic composite for insulating and/or encapsulating electrical components which includes a polymer matrix and a micro-size and/or nano-size filler. The polymer matrix may be polyamide, polyimide, fluoropolymer, polyester, polyolefin, polystyrene, cyclic olefin copolymer, and blends thereof. The filler is in a form of micro-particle, micro-tube, micro-platelet, micro-fiber, nanoparticle, nanotube, nanoplatelet, nano-fiber, and blends thereof. The patent application is silent on the high-voltage resistance of any thermoplastic composite. Particularly, polyamide is mentioned as an option of the polymer matrix in the patent application, but no application and performance tests of this material are described. It is very challenging to develop thermoplastic polyamide materials with desirable high-voltage insulating performance.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a polyamide composition useful as insulating materials in high-voltage applications, which is high-voltage resistant and preferably exhibits excellent toughness, color stability and/or reduced moisture uptake.

It was surprisingly found by the inventors that the object can be achieved by a polyamide composition comprising a long-chain polyamide and a lamellar filler having a high diameter-to- thickness ratio (D/T ratio).

Accordingly, in the first aspect, the present invention provides a polyamide composition comprising

(A) from 40% to 80% by weight of a polyamide containing at least one type of monomer units having at least 8 carbon atoms, and

(B) from 20% to 60% by weight of a filler in a lamellar shape having a diameter-to-thickness ratio of at least 70, based on the total weight of the polyamide composition.

In the second aspect, the present invention relates to use of the polyamide composition as described herein as insulating materials in high-voltage transmission and distribution systems, particularly in circuit breakers, reclosers and transformers.

In the third aspect, the present invention relates to articles produced using the polyamide composition as described herein, particularly articles in high-voltage transmission and distribution systems, such as circuit breakers, reclosers and transformers.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will be described in detail hereinafter. It is to be understood that the present invention can be embodied in many different ways and shall not be construed as limited to the embodiments set forth herein.

The singular forms “a”, “an” and “the” include plural referents unless the context clearly dictates otherwise. The terms “comprise”, “comprising”, etc. are used interchangeably with “contain”, “containing”, etc. and are to be interpreted in a non-limiting, open manner. That is, e.g., further components or elements can be present. The expressions “consists of” or “consisting of” or cognates can be embraced within “comprises” or “comprising” or cognates.

Different aspects of the invention are defined in more detail. Each aspect so defined may be combined with any other aspect or aspects unless clearly indicated to the contrary. In particular, any feature indicated as being preferred may be combined with any other feature or features described generally or indicated as being preferred.

Herein, any reference to “some embodiments” means that a particular component, amount, composition or feature described in connection with the embodiments is included in some exemplary embodiments of the present invention. Thus, appearance of the phrase “in some embodiments” or similar phrases in various places throughout the description are not necessarily all referring to the same embodiments, but may. Furthermore, the component, amount, composition or feature may be combined in any suitable manners as would be apparent to the skilled person from the disclosure in more embodiments.

Herein, the terms “high-voltage” and “high voltage” relate to alternating current (AC) voltages of 1 kV or higher, particularly from 1.5 kV or higher, more particularly 2.0 kV or higher.

Herein, the term “diameter-to-thickness ratio” refers to a value according to the following equation,

D/T=3TT x (D_a/D_s)²/2 wherein

D_a is particle diameter (D50) based on static laser light diffraction method according to GB/T 19077-2016, and

D_s is particle diameter (D50) based on gravitational liquid sedimentation method according to ISO 13317-3:2001.

The determination of “diameter-to-thickness ratio” is known and for example described in Daniel Gantenbein et al., "Determining the size distribution-defined aspect ratio of platy particles", Applied Clay Science 53 (2011), pages 544 to 552. Herein, the term “D/T ratio” is also used as an abbreviation for the diameter-to-thickness ratio.

As used herein, the term “structural unit(s)”, also referred to “monomer unit(s)”, is intended to refer to the minimal molecular residue(s) resulting from respective monomer molecules after polymerization. For example, PA6 has a type of structural unit of -NH(CH2)5CO-, PA66 has two types of structural units, i.e. , -NH(CH2)eNH- and -CO(CH2)4CO-, and so on.

As used herein, the term “repeating unit(s)” is intended to refer to the minimal unit(s) with same chemical composition in a polymer. The repeating units can consist of one or more types of structural units. For example, PA6 has repeating units same as the structural units, i.e., - NH(CH2)SCO-; PA66 has repeating units of -NH(CH2)eNHCO(CH2)4CO- which consist of two types of structural units, i.e., -NH(CH2)eNH- from the diamine monomer and -CO(CH2)4CO- from the dicarboxylic acid monomer.

Polyamide Composition

In the first aspect, the present invention provides a polyamide composition comprising (A) from 40% to 80% by weight of a polyamide containing at least one type of monomer units having at least 8 carbon atoms, and

(A) Polyamide

Polyamide, as well known in the art, refers to a polymer that contains repeating amide moieties (-CONH-) in the main chain of the polymers. Generally, a polyamide is made up of many identical repeating units linked by covalent bonds. It is well-known that the repeating units of a polyamide are typically derived one or more monomers selected from lactams, amino acids, a combination of dicarboxylic acid and diamine, and a combination of dicarboxylic acid chloride and diamine.

Suitable polyamides as component (A) in the polyamide composition according to the present invention may have repeating units of formula (I):

O

- [-NH- R¹- C-P _(|)i in which

R¹ is an unsubstituted or substituted straight-chain C?-24-alkylene, preferably Cs-2o-alkylene, more preferably Cg- -alkylene.

The straight-chain C?-24-alkylene, Cs-2o-alkylene or Cg- -alkylene given for R¹ in formula (I) may be unsubstituted or substituted by Ci-s-alkyl, particularly Ci-e-alkyL

The polyamide having repeating units of formula (I) is typically derived from at least one aliphatic monomer selected from lactams, amino acids or any combinations thereof. Suitable lactams preferably have from 8 to 25 carbon atoms, more preferably from 9 to 21 carbon atoms, particularly from 10 to 17 carbon atoms. Examples of the lactams may include, but are not limited to, caprylolactam (2-azacyclononanone), caprinolactam (azacycloundecan-2-one), laurolactam (2-Azacyclotridecanone), or any combinations thereof. Suitable amino acids preferably have from 8 to 25 carbon atoms, more preferably from 9 to 21 carbon atoms, particularly from 10 to 17. Examples of the amino acids may include, but are not limited to, 8- aminocaprylic acid, 10-aminodecanoic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid or any combinations thereof.

Alternatively, suitable polyamides as component (A) in the polyamide composition according to the present invention may have repeating units of formula (II): in which R² is an unsubstituted or substituted straight-chain C4-24-alkylene, preferably C4-2o-alkylene, more preferably C4-i6-alkylene, and

R³ is an aliphatic or aromatic C4-3o-hydrocarbylene, preferably C6-2o-hydrocarbylene, more preferably Ce-ie-hydrocarbylene, o o , H , H provided that at least one of moiety of -NH-R -NH- and moiety of — c— R°-C — has at least 8 carbon atoms.

The straight-chain C4-24-alkylene, C4-2o-alkylene or C4-i6-alkylene given for R² in formula (II) may be unsubstituted or substituted by Ci-s-alkyl, particularly Ci-e-alkyL

The C4-3o-hydrocarbylene, C6-2o-hydrocarbylene or Ce- -hydrocarbylene given for R³ in formula (II) may be unsubstituted or substituted alkylene, cycloalkylene or arylene. Preferably R³ is Ce- 20-alkylene, C6-2o-cycloalkylene or C6-2o-arylene group, more preferably Ce- -alkylene, Ce- - cycloalkylene or Ce- -arylene group.

The polyamide having repeating units of formula (II) is typically derived from an aliphatic or aromatic dicarboxylic acid or dicarboxylic acid chloride having from 6 to 32 carbon atoms and an aliphatic diamine having from 4 to 24 carbon atoms, provided that at least one of the diamine and the dicarboxylic acid or dicarboxylic acid chloride has at least 8 carbon atoms.

The aliphatic diamines may be straight-chain or branched. Examples of the aliphatic diamines may include, but are not limited to, 1 ,5-hexanediamine, 1 ,6-hexanediamine, 1 ,7- heptanediamine, 1 ,8-octanediamine, 1 ,9-nonanediamine, 1 ,10-decanediamine, 1 ,11- undecanediamine, 1 ,12-dodecanediamine, 1 ,13-tridecanediamine, 1 ,14-tetradecanediamine, 1 ,16-hexadecanediamine, 1 ,18-octadecanediamine, 1 ,20-eicosanediamine, 1 ,22- docosanediamine, 2,3-dimethylheptane-1 ,7-diamine, 2,4-dimethylheptane-1 ,7-diamine, 2,5- dimethylheptane-1 ,7-diamine, 2,2-dimethylheptane-1 ,7-diamine, 2-methyloctane-1 ,8-diamine, 1 ,3-dimethyloctane-1 ,8-diamine, 1 ,4-dimethyloctane-1 ,8-diamine, 2, 4-dimethyloctane-1 ,8- diamine, 3,4-dimethyloctane-1 ,8-diamine, 4,5-dimethyloctane-1 ,8-diamine, 2,2- dimethyloctane-1 ,8-diamine, 3, 3-dimethyloctane-1 ,8-diamine, 4, 4-dimethyloctane-1 ,8- diamine, 5-methylnonane-1 ,9-diamine, and any combinations thereof.

Examples of the dicarboxylic acids may include, but are not limited to, adipic acid, pimelic acid, suberic acid, nonanoic acid, sebacic acid, undecanedioic acid, dodecandioic acid, tridecanedioic acid, tetradecandioic acid, pentadecandioic acid, hexadecanedioic acid, octadecandioic acid, terephthalic acid, isophthalic acid, and any combinations thereof.

Examples of the dicarboxylic acid chlorides may include, but are not limited to, adipoyl dichloride, heptanedioyl dichloride, octanoyl chloride, azelaoyl dichloride, sebacoyl dichloride, undecanedioyl dichloride, lauroyl dichloride, tridecanedioyl dichloride, tetradecandioyl dichloride, pentadecandioyl dichloride, hexadecanedioyl dichloride, octadecandiooyl dichloride, terephthaloyl chloride, isophthaloyl acid, and any combinations thereof. For example, the polyamide as component (A) may be selected from the group consisting of PA11, PA12, PA510, PA610, PA612, PA1010, PA1012, PA1212, PA9T, PA10T, PA11T, PA12T or any combinations thereof.

Useful polyamides may also be a blend of polyamides as described above or a copolymerized polyamide (co-polyamide). There is no limitation to the type of the co-polyamide, which may be for example a block copolymer, a random copolymer, a graft copolymer or an alternating copolymer, for example PA10T/610, PA5T/510, PA10T/1010, PA9T/612, PA9T/1010 or any combinations thereof.

In some embodiments according to the present invention, the polyamide having the repeating units of formula (II) is particularly useful as component (A) in the polyamide composition, among which PA1212, PA610 and PA9T are more preferable.

The polyamide as component (A) in the polyamide composition according to the present invention may have any suitable molecular weights without being limited. The relative viscosity of the polyamide is in the range of from 1.8 to 4.0, as measured in 96 % by weight sulfuric acid at 25°C.

The polyamides as component (A) in the polyamide composition according to the present invention may have any suitable melting temperatures without being limited. For example, the melting temperature is in the range of from 150 to 350 °C, as measured by Differential Scanning Calorimetry (DSC).

The component (A) may be present in the polyamide composition according to the present invention in an amount of from 40% to 80% by weight, for example from 45% to 70% by weight or from 50% to 65% by weight, based on the total weight of the polyamide composition.

The polyamide disclosed herein should not be limited to the ones prepared from virgin crude oil monomers, and could be completely or at least partially biobased or derived from waste stream or recycling activities, i.e., the polyamide used in the present invention can be based on renewable materials, secondary raw materials or recycled raw materials. For example, PA610, PA1212, PA9T, PA10T and PA11T useful as component (A) in the present invention could be prepared or obtained or derived from monomers that obtained in a re-monomerisation processes.

(B) Filler in a Lamellar Shape

The polyamide composition according to the present invention comprises a filler in a lamellar shape (also referred to as “lamellar filler” herein) having a diameter-to-thickness ratio of at least 70, preferably at least 100, as the component (B).

There is no particular restriction to the upper limit of the diameter-to-thickness ratio. The lamellar filler may have a diameter-to-thickness ratio of no higher than 250, for example no higher than 200 or no higher than 150. The lamellar filler may have a diameter-to-thickness ratio in the range of from 70 to 250, or from 70 to 200, or from 70 to 150, preferably in the range of from 100 to 250, or from 100 to 200, or from 100 to 150.

The lamellar filler may have a particle size D50 in the range of 1 to 30 microns (pm), more preferably in the range of from 3 to 20 pm, as measured by using a laser diffraction particle size distribution analyzer.

The lamellar filler may be microplatelets or nanoplatelets, preferably microplatelets. Materials useful as the lamellar filler may be organic, such as polymeric materials which will not melt during processing the polyamide composition (such as blending and molding), or inorganic, such as refractory synthetic compounds or natural minerals. Preferably, the lamellar filler is inorganic. Examples of materials useful as the inorganic lamellar filler may include, but are not limited to boron nitride, kaolin, chalk, talc, calcium carbonate, silicates, graphite, mica, vermiculite, montmorillonite and glass.

The lamellar filler may be present in the polyamide composition according to the present invention in an amount of from 20% to 60% by weight, preferably from 25% to 55% by weight, more preferably from 25% to 50% by weight, based on the total weight of the polyamide composition.

Particularly, the lamellar filler may be present in the polyamide composition according to the present invention in an amount of from 20% to 60% by weight, preferably from 30% to 55% by weight, more preferably from 35% to 50% by weight when the polyamide composition comprises at least one additional filler in an amount of no higher than 5% by weight, based on the total weight of the polyamide composition.

(C) Additional Filler

Optionally, the polyamide composition according to the present invention may comprise an additional filler, i.e. , a filler other than the component (B) (i.e., the filler in a lamellar shape having a diameter-to-thickness ratio of at least 70).

The additional filler may be of various types without particular restrictions, such as fibers, whiskers, platelets and particles. The additionally filter may be particularly selected from fibrous fillers and particulate fillers.

Examples of the fibrous fillers may include, but are not limited to metal fibers such as brass fibers, stainless steel fibers, steel fibers, metalized inorganic fibers, metalized synthetic fibers, glass fibers, carbon fibers, boron fibers, asbestos fibers, ceramic fibers, mineral fibers, basalt fibers, kenaf fibers, jute fibers, bamboo fibers, flax fibers, hemp fibers, bagasse fibers, cellulosic fibers, sisal fibers, and coir fibers. Preferably, the fibrous fillers may be selected from metalized synthetic fibers, glass fibers, carbon fibers, ceramic fibers, mineral fibers, basalt fibers, kenaf fibers and jute fibers, among which glass fibers and carbon fibers are more preferable.

There is no particular restriction to the fiber length and the fiber diameter of the fibrous fillers. For example, chopped fibers having a length in the range of from 1 to 10 mm, preferably from 2 to 6 mm, or continuous fibers may be used as starting material of the reinforcing agent. The fibers will be broken down during processing, for example kneading the polyamide composition, to a length of a few hundreds of microns as present in the obtained moldings. The fiber diameter is generally in the range of from 3 to 20 pm, preferably from 7 to 13 pm. The fibrous fillers may have a cross section with an aspect ratio in the range of from 1 : 1 to 5 : 1.

Glass fibers are particularly useful as the additional filler in the polyamide composition according to the present invention. The glass fibers may have been surface-treated by a silane coupling agent, such as vinylsilane-based coupling agents, acrylic silane-based coupling agents, epoxysilane-based coupling agents and aminosilane-based coupling agents, preferable aminosilane-based coupling agents. The silane coupling agent may be dispersed in a sizing agent. Examples of the sizing agents are acrylic compounds, acrylic/maleic derivative modified compounds, epoxy compounds, urethane compounds, urethane/maleic derivative modified compounds and urethane/amine modified compounds.

Particulate fillers may be organic or inorganic fillers and have a variety of particle sizes, ranging from particles in dust form to coarse particles. Examples of materials that may be used as inorganic particulate fillers include, but are not limited to kaolin, chalk, wollastonite, talc, calcium carbonate, silicates, titanium dioxide, zinc oxide, graphite, mica, vermiculite, montmorillonite, and glass particles (e.g., glass beads).

In some embodiments, the additional filler as the component (C) is selected from glass fibers. The glass fibers may be for example E-glass fibers, A-glass fibers, D-glass fibers, AR-glass fibers, C-glass fibers and S-glass fibers, or any other high modulus or high strength glass fibers such as M-glass fibers and HMG glass fibers.

The additional filler, if comprised, may be present in the polyamide composition according to the present invention in an amount of no higher than 20% by weight, no higher than 15%, no higher than 10%, or no higher than 5%.

In some embodiments, the additional filler may be present in an amount of for example from 5% to 20% by weight, more preferably from 5% to 15% by weight, based on the total weight of the polyamide composition.

Accordingly, in some embodiments, the present invention provides a polyamide composition comprising

(A) from 40% to 80% by weight of a polyamide containing at least one type of monomer units having at least 8 carbon atoms, (B) from 20% to 60% by weight of a filler in a lamellar shape having a diameter-to-thickness ratio of at least 70, and

(C) from 0% to 20% by weight of a filler other than the filler in a lamellar shape having a diameter-to-thickness ratio of at least 70, based on the total weight of the polyamide composition.

It will be understood that the sum of the lamellar filler as component (B) and the additional filler as component (C) will not be higher than 60% by weight, based on the total weight of the polyamide composition. Preferably, the sum of the lamellar filler as component (B) and the additional filler as component (C) will not be higher than 55% by weight, particularly 50% by weight, based on the total weight of the polyamide composition.

D) Additives

Optionally, the polyamide composition according to the present invention may comprise at least one additive, for example, UV absorber, hindered amine light stabilizer, antioxidant, lubricant, nucleating agent, colorant, release agent, anti-dripping agent, impact modifier, compatibilizing agent, plasticizer, surfactant, flame retardant, flame retardant synergist, coupling agent, antimicrobial agent, antistatic agents and any combinations thereof.

The at least one additive, if comprised, may be present in conventional amounts. For example, the polyamide composition may comprise the at least one additional additive in a total amount of no higher than 25% by weight, or no higher than 15% by weight, or no higher than 10% by weight, based on the total weight of the polyamide composition.

In some embodiments, the polyamide composition according to the present invention comprises a UV absorber. There is no particular restriction to the UV absorber useful for the polyamide composition according to present invention, which may be selected from any known UV absorbers, for example hydroxyphenyl benzotriazoles, hydroxyphenyl triazines, benzophenones, cyanoacrylates, benzoxazinones, benzylidene malonates, and salicylate esters, and any combinations thereof. Examples of useful commercially available UV absorbers may include, but are not limited to, Tinuvin® 328 (2-(2'-hydroxy-3',5'-di-tert- amylphenyl)benzotriazole), Tinuvin® 360 (2,2'-methylene bis[6-(2H-benzotriazol-2-yl)-4- 1 ,1 ,3,3-tetramethylbutyl)phenol]), Tinuvin® 900 (2-[2-hydroxy-3,5-bis(a,a- dimethylbenzyl)phenyl]-2H-benzotriazole), Tinuvin® 1577 ED (2-(4,6-diphenyl-1 ,3,5-triazin-2- yl)-5-hexyloxyphenol), Tinuvin® 1600 (2,4-bis-biphenyl-6-[2-hydroxy-4-(2- ethylhexyloxy)phenyl]-1,3,5-triazine), Cyasorb® UV-531 (2-hydroxy-4-cctyloxy benzophenone), Cyasorb® UV-1164 (2-(4,6-bis(2,4-dimethylphenyl)-1 ,3,5-triazin-2-yl)-5- (octyloxy) phenol.

The UV absorber, if comprised, may be present in an amount of from 0.05% to 5% by weight, preferably from 0.1 % to 2% by weight, based on the total weight of the polyamide composition. In some embodiments, the polyamide composition according to the present invention comprises a hindered amine light stabilizer (HALS). There is no particular restriction to the hindered amine light stabilizer useful for the polyamide composition according to present invention, which may be selected from any known hindered amine light stabilizers, for example the monomeric, oligomeric and polymeric compounds based on 2,2,6,6-tetramethylpiperidine. Examples of useful commercially available UV absorbers may include, but are not limited to, Chimassorb® 944 (poly-{6- [( 1 , 1 ,3,3-tetramethylbutyl)amino-1 , 3, 5-triazi ne-2 , 4-d iy I] [(2 , 2 , 6 , 6- tetramethyl-4-piperidyl)imino]-1,6-hexanediyl[(2,2,6,6-tetramethyl-4-piperidyl)imino)}), Chimassorb® 2020 (1 ,6-hexanediamine, N,N’-bis(2,2,6,6-tetramethyl-4-piperidinyl)-polymer with 2,4,6-trichloro-1 ,3,5-triazine, reaction products with N-butyl-1-butanamine and N-butyl- 2,2,6,6-tetramethyl-4-piperidinamine), Tinuvin® 123 (bis(1-octyloxy-2,2,6,6-tetramethyl-4- piperidinyl) sebacate), Tinuvin® 770 (bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate), Tinuvin® 292 (bis(1 ,2,2,6,6-pentamethyl-4-piperidyl) sebacate), Cyasorb® UV-3529 (1 ,6- hexanediamine, N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-, polymer with morpholine-2,4,6- trichloro- 1 ,3,5-triazine)

The hindered amine light stabilizer, if comprised, may be present in an amount of from 0.05% to 3% by weight, preferably from 0.1% to 1% by weight, based on the total weight of the polyamide composition.

In some embodiments, the polyamide composition according to the present invention comprises an antioxidant. There is no particular restriction to the antioxidant useful for the polyamide composition according to present invention, which may be selected from any known antioxidants, for example hindered phenol antioxidants, phosphite antioxidants, phosphonites antioxidants, aromatic amine antioxidants, and any combinations thereof. Examples of useful commercially available UV absorbers may include, but are not limited to, Irganox® 1098 (N,N - (hexane-1 ,6-diyl) bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanamide]), Irganox® 1010 (pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate)), lrganox®1726 (2,4- bis[(dodecylthio)methyl]-o-cresol), lrganox®1035 (2,2-thiodiethylene bis[3-(3,5-di-tert-butyl-4- hydroxyphenyl) propionate]), Irgafos® 168 (tris(2,4-di-tert-butylphenyl)phosphite), Doverphos® S-9228 (bis(2,4-dicumylphenyl)pentaerythritol diphosphite), Doverphos® TNPP (trisnonylphenol phosphite), ULTRANOX® 627 (bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphonite), Doverphos® S-9228PC (bis(2,4-dicumylphenyl)pentaerythritol diphosphite), Hostanox® P-EPQ (tetrakis(2,4-di-tert-butylphenyl) [1 , 1 -biphenyl]-4,4’-diyl bisphosphonite).

The antioxidant, if comprised, may be present in an amount of from 0.01% to 5% by weight, for example 0.1 % to 2% by weight, based on the total weight of the polyamide composition.

In some embodiments, the polyamide composition according to the present invention comprises a lubricant. There is no particular restriction to the lubricant useful for the polyamide composition according to present invention, which may be selected from any known lubricants, for example, long-chain fatty acids and salts thereof such as stearic acid or behenic acid and salts thereof, esters or amides of saturated or unsaturated aliphatic carboxylic acids such as N,N’-ethylene di(stearamide), glycerol distearate, glycerol tristearate, glycerol monopalmitate, glycerol trilaurate, glycerol monobehenate and pentaerythritol tetrastearate, and waxes such as natural waxes, montan waxes, paraffin waxes, polyethylene waxes and polypropylene waxes.

The lubricant, if comprised, may be present in an amount of from 0.1% to 5% by weight, for example from 0.3% to 3% by weight, based on the total weight of the polyamide composition.

In some embodiments, the polyamide composition according to the present invention comprises a nucleating agent. There is no particular restriction to the nucleating agent useful for the polyamide composition according to present invention, which may be selected from any known nucleating agents, for example talc, boron nitride, mica, kaolin, alkali metal or alkali earth metal carbonates, bicarbonates or sulfates, alkali metal titanates, silicon nitride, and molybdenum disulfide.

The nucleating agent, if comprised, may be present in an amount of from 0.01 % to 5% by weight, preferably from 0.01 % to 2% by weight, based on the total weight of the polyamide composition.

Formulations

It will be understood that any options with respect to species and/or amounts as described herein generally or with preference for the components A), B), C), D) may be combined in any way without any restriction. For example, a combination of a general range of the amount of one component with any preferable ranges of the amounts of other components, or a combination of a preferable range of the amount of one component with general ranges of the amounts of the other components, and so on are included in the present invention.

Following embodiments will be described as examples of the formulations of the polyamide composition according to the present invention.

In some embodiments, the polyamide according to the present invention comprises

(A) from 40% to 80% by weight of a polyamide containing at least one type of monomer units having at least 8 carbon atoms,

(B) from 20% to 60% by weight of a filler in a lamellar shape having a diameter-to-thickness ratio of at least 70,

(C) from 0% to 20% by weight of a filler other than the filler in a lamellar shape having a diameter-to-thickness ratio of least 70, and

(D) from 0% to 25% by weight of an additive, based on the total weight of the polyamide composition.

In some further embodiments, the polyamide according to the present invention comprises

(A) from 45% to 70% by weight of a polyamide containing at least one type of monomer units having at least 8 carbon atoms, (B) from 25% to 55% by weight of a filler in a lamellar shape having a diameter-to-thickness ratio of at least 70,

(C) from 0% to 20% by weight of a filler other than the filler in a lamellar shape having a diameter-to-thickness ratio of at least 70, and

In yet further embodiments, the polyamide according to the present invention comprises

(A) from 50% to 65% by weight of a polyamide containing at least one type of monomer units having at least 8 carbon atoms,

(B) from 25% to 50% by weight of a filler in a lamellar shape having a diameter-to-thickness ratio in the range of at least 70,

(C) from 0% to 20% by weight of a filler other than the filler in a lamellar shape having a diameter-to-thickness ratio in the range of at least 70, and

In some particular embodiments, the polyamide according to the present invention comprises

(A) from 45% to 70% by weight of a polyamide containing at least one type of monomer units having at least 8 carbon atoms,

(B) from 25% to 50% by weight of a filler in a lamellar shape having a diameter-to-thickness ratio of at least 70,

(C) from 5% to 20% by weight of a filler other than the filler in a lamellar shape having a diameter-to-thickness ratio of at least 70, and

Preferably, the polyamide according to the present invention comprises

(B) from 25% to 45% by weight of a filler in a lamellar shape having a diameter-to-thickness ratio of at least 70,

(C) from 5% to 15% by weight of a filler other than the filler in a lamellar shape having a diameter-to-thickness ratio of at least 70, and

(D) from 0% to 15% by weight of an additive, based on the total weight of the polyamide composition.

In some other particular embodiments, the polyamide according to the present invention comprises

(B) from 30% to 55% by weight of a filler in a lamellar shape having a diameter-to-thickness ratio of at least 70, (C) from 0% to 5% by weight of a filler other than the filler in a lamellar shape having a diameter- to-thickness ratio of at least 70, and

Preferably, the polyamide according to the present invention comprises

(B) from 35% to 50% by weight of a filler in a lamellar shape having a diameter-to-thickness ratio of at least 70,

(C) from 0% to 5% by weight of a filler other than the filler in a lamellar shape having a diameter- to-thickness ratio of at least 70, and

The polyamide composition according to the present invention may be processed by any conventional methods without particular restrictions. The method usually includes at least the step of compounding the components as described herein. Compounding per se is a technique which is well known to the skilled person in the art of polymer processing and manufacturing, and comprises preparing plastic formulations by mixing and/or blending the components in a molten state. The mixing may be carried out at a rotational speed ranging from 200 rpm to 320 rpm. It is understood in the art that compounding is distinct from blending or mixing processes conducted at temperatures lower than a temperature at which the components become molten. Compounding may, for example, be used to form a masterbatch composition. Compounding may, for example, involve adding a masterbatch composition to a polymer to form a further polymer composition. The compounding may be carried out at a temperature of from 220°C to 350 °C.

The polyamide composition may be processed and shaped into a desired form of articles, for example by molding such as compression molding, injection molding, stretch blow molding, injection blow molding, hollow molding, extrusion, casting or thermoforming.

Use of the Polyamide Composition

As found by the inventors surprisingly, the polyamide composition according to the present invention as insulating materials could exhibit a superior high-voltage resistance, while exhibiting good dielectric strength and electrical resistivity.

Accordingly, in the second aspect, the present invention provides use of the polyamide composition as described herein as insulating materials in high-voltage transmission and distribution systems.

Particularly, the present invention provides use of the polyamide composition as described herein as insulating materials in circuit breakers, reclosers and transformers. Articles

In the third aspect, the present invention relates to articles produced using the polyamide composition as described herein. The articles produced using the polyamide composition are useful in various applications, particularly in high-voltage transmission and distribution systems.

For example, the articles produced using the polyamide composition may be circuit breakers, reclosers and transformers in high-voltage transmission and distribution systems.

Embodiments

Various embodiments are listed below. It will be understood that the embodiments listed below can be combined with all aspects and other embodiments in accordance with the scope of the invention.

1. A polyamide composition, which comprises

2. The polyamide composition according to Embodiment 1 , wherein the polyamide is selected from PA11 , PA12, PA510, PA610, PA612, PA1010, PA1012, PA1212, PA9T, PA10T, PA11T, PA12T or any combinations thereof, among which PA610, PA1212 and PA9T are preferable.

3. The polyamide composition according to Embodiment 1 or 2, wherein the polyamide is present in an amount of from 45% to 70% by weight, based on the total weight of the polyamide composition.

4. The polyamide composition according to Embodiment 3, wherein the polyamide is present in an amount of from 50% to 65% by weight, based on the total weight of the polyamide composition.

5. The polyamide composition according to any of preceding Embodiments, wherein the diameter-to-thickness ratio of the filler in a lamellar shape is at least 100.

6. The polyamide composition according to any of preceding Embodiments, wherein the diameter-to-thickness ratio of the filler in a lamellar shape is no higher than 250. 7. The polyamide composition according to Embodiment 6, wherein the diameter-to- thickness ratio of the filler in a lamellar shape is no higher than no higher than 200.

8. The polyamide composition according to Embodiment 7, wherein the diameter-to- thickness ratio of the filler in a lamellar shape is no higher than no higher than 150.

9. The polyamide composition according to any of preceding Embodiments, wherein the filler in a lamellar shape is selected from microplatelets or nanoplatelets of boron nitride, kaolin, chalk, talc, calcium carbonate, silicates, graphite, mica, vermiculite, montmorillonite, glass or any combinations thereof.

10. The polyamide composition according to any of preceding Embodiments, wherein the filler in a lamellar shape is present in an amount of from 25% to 55% by weight, based on the total weight of the polyamide composition.

11. The polyamide composition according to Embodiment 10, wherein the filler in a lamellar shape is present in an amount of from 25% to 50% by weight, based on the total weight of the polyamide composition.

12. The polyamide composition according to any of preceding Embodiments, which comprises C) an additional filler other than the filler in a lamellar shape in an amount of no higher than 20% by weight, based on the total weight of the polyamide composition.

13. The polyamide composition according to Embodiment 12, which comprises the filler in a lamellar shape in an amount of from 30% to 55% by weight and the additional filler in an amount of no higher than 5% by weight, based on the total weight of the polyamide composition.

14. The polyamide composition according to Embodiment 13, which comprises the filler in a lamellar shape in an amount of from 35% to 50% by weight and the additional filler in an amount of no higher than 5% by weight, based on the total weight of the polyamide composition.

15. The polyamide composition according to an of preceding Embodiments 12 to 14, wherein the additional filler is selected from glass fibers.

16. The polyamide composition according to any of preceding Embodiments, which comprises at least one additive selected from UV absorber, hindered amine light stabilizer, antioxidant, lubricant, nucleating agent, colorant, release agent, anti-dripping agent, impact modifier, compatibilizing agent, plasticizer, surfactant, flame retardant, flame retardant synergist, coupling agent, antimicrobial agent and antistatic agents.

17. The polyamide composition according to Embodiment 16, which comprises a UV absorber in an amount of from 0.05% to 5% by weight, preferably from 0.1% to 2% by weight, based on the total weight of the polyamide composition. 18. The polyamide composition according to Embodiment 16 or 17, which comprises a hindered amine light stabilizer, in an amount of from 0.05% to 3% by weight, preferably from 0.1% to 1% by weight, based on the total weight of the polyamide composition.

19. Use of the polyamide composition according to any of preceding Embodiments as insulating materials in high-voltage transmission and distribution systems.

20. The use of the polyamide composition according to Embodiment 19 in circuit breakers, reclosers and transformers.

21. Articles produced using the polyamide composition according to any of preceding Embodiments 1 to 18.

22. The articles according to Embodiment 21 , which are articles in high-voltage transmission and distribution systems, such as circuit breakers, reclosers and transformers.

EXAMPLES

Aspects of the present invention will be more fully illustrated by the following Examples, which are set forth to illustrate certain aspects of the present invention and are not to be construed as limiting thereof.

Materials

Preparation of Test Specimens

Test specimens were prepared in accordance with the formulations as shown in Table 1 below.

All raw materials except the filler were mixed together in a Turbula T50A high-speed stirrer and fed into a ZE25Ax (Berstorff) twin-screw extruder at the throat, and then the filler was fed at downstream using a side feeder. The mixed materials were melt-extruded under a temperature of 320°C for PA9T, 285°C for PA66, 275°C for PA6, 275°C for PA610 and 220°C for PA1212, and pelletized to obtain the polyamide composition in a pellet form. The screw diameter is 26 mm, the screw speed is 300 rpm, and the throughput is 15 to 30 kg/h.

The dried pellets were processed in an injection molding machine KM130CX from Krauss Maffei with a clamping force of 130T at a melt temperature of 240°C to 320°C depending on the specific polyamide to obtain test specimens.

Measurements and Test Methods

(1) Diameter-to-Thickness Ratio (D/T ratio)

The D/T ratio was calculated in accordance with the following equation

D/T=3TT x (D_a/D_s)²/2 wherein

D_a is particle diameter (D50) based on static laser light diffraction method according to GB/T 19077-2016 as measured by using Malvern Mastersizer 2000, and

D_s is particle diameter (D50) based on gravitational liquid sedimentation method according to ISO 13317-3:2001 as measured by using Micromeritics Sedigraph 5100.

(2) Mechanical Properties

Tensile strength, tensile modulus, tensile elongation, flexural modulus and flexural strength were measured for specimens having thickness of 4 mm on the testing machine Z050 (Zwick Roell, Germany) according to ISO 527-1-2012. Test specimens of type 1 described in ISO 527- 1-2012 were used.

Charpy notched impact strength and Charpy unnotched impact strength were measured on the testing machine HIT25P (Zwick Roell, Germany) according to ISO 179-1-2010 via edgewise impact. The test specimens for Charpy unnotched test is type 1 specimen with the dimensions of 80 mm x 10 mm x 4 mm (length x width x thickness). The test specimens for Charpy notched test are type 1 with notched type A.

All the test specimens were conditioned at 23°C and 50% relative humidity for 16 hours. The tests were conducted under the same atmosphere as conditioning.

(3) Insulating Properties

Resistance to tracking and erosion under high voltage was evaluated by inclined plane test (I PT) according to GB/T 6553-2014, corresponding to I EC 60587:2007. The specimens (130 mm x 50 mm x 4 mm) were tested under a voltage of 2.0 and 3.5 kV using a time-to-track method.

Dielectric strength measurement was performed according to IEC 60243-1 :2013, using a short time (rapid rise) method. The specimens with thickness of 2 mm were preconditioned at 23°C, 50% relative humidity for 24 hours, and tested under a frequency of voltage application of 50 Hz. The rate-of-rise was 2000 V/s.

Dielectric loss measurement was performed according to IEC 62631-2-1 :2018. The specimens with thickness of 2 mm were preconditioned at 23°C, 50% relative humidity for 96 hours and tested under a frequency of 1 M Hz.

Volume resistivity and surface resistivity were tested under 500 V according to IEC 62631-3- 1 :2016 with a sample thickness of 3 mm.

The formulations and results for the polyamide compositions as tested were summarized in Table 1.

Table 1

not determined; “Comp.”: Comparative Example; “Ex. Example

As can be seen from the results shown in Table 1 , the specimens of Ex. 2, Ex.3 and Ex. 7 prepared from the polyamide compositions comprising PA9T and the lamellar talc filler having a high D/T ratio according to the present invention exhibit excellent resistance to tracking and erosion under a voltage as high as 2.0 kV, for which a failure mode (current > 60 mA or breakdown, fire during testing) was not observed over 213 min and even 360 min (i.e. , 6 hours). Such an excellent performance will surely meet the actual operating conditions in high-voltage transmission and distribution applications. On the contrary, each of the specimens prepared from the comparative polyamide compositions comprising PA9T and a non-lamellar filler (Comp. 2 to Comp. 5), from the comparative polyamide compositions comprising PA9T and the lamellar talc filler having a low D/T ratio (Comp. 1), and from the comparative polyamide compositions comprising PA6 or PA66 and the lamellar talc filler (Comp. 6 and Comp. 7) exhibits very poor resistance to high voltage at 2.0 kV, for which the failure mode was observed just after less than 1 hour, even a few minutes. The specimen of Ex. 8 prepared from the polyamide compositions comprising PA9T and the lamellar talc filler having a high D/T ratio according to the present invention also exhibits a significantly improved resistance to tracking and erosion even at a much lower dosage of the lamellar talc filler, compared with the specimens prepared from the comparative polyamide compositions.

Similarly, each of the specimens prepared from polyamide compositions comprising PA9T, PA610 or PA1212 and the lamellar boron nitride filler (Ex. 1 , Ex. 4 to Ex. 6) also exhibits excellent resistance to high voltage at 2.0 kV.

It will be apparent to one of ordinary skill in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the present invention. It is intended that the embodiments and examples be considered as exemplary only. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.

Claims

1 . A polyamide composition, which comprises

(B) from 20% to 60% by weight of a filler in a lamellar shape having a diameter-to- thickness ratio of at least 70, based on the total weight of the polyamide composition.

2. The polyamide composition according to claim 1 , wherein the polyamide is selected from PA11 , PA12, PA510, PA610, PA612, PA1010, PA1012, PA1212, PA9T, PA10T, PA11T, PA12T or any combinations thereof, among which PA610, PA1212 and PA9T are preferable.

3. The polyamide composition according to claim 1 or 2, wherein the polyamide is present in an amount of from 45% to 70% by weight or from 50% to 65% by weight, based on the total weight of the polyamide composition.

4. The polyamide composition according to any of preceding claims, wherein the diameter- to-thickness ratio of the filler in a lamellar shape is at least 100.

5. The polyamide composition according to any of preceding claims, wherein the diameter- to-thickness ratio of the filler in a lamellar shape is no higher than 250, or no higher than 200, or no higher than 150.

6. The polyamide composition according to any of preceding claims, wherein the filler in a lamellar shape is selected from microplatelets or nanoplatelets of boron nitride, kaolin, chalk, talc, calcium carbonate, silicates, graphite, mica, vermiculite, montmorillonite, glass or any combinations thereof.

7. The polyamide composition according to any of preceding claims, wherein the filler in a lamellar shape is present in an amount of from 25% to 55% by weight, more preferably from 25% to 50% by weight, based on the total weight of the polyamide composition.

8. The polyamide composition according to any of preceding claims, which comprises C) an additional filler other than the filler in a lamellar shape in an amount of no higher than 20% by weight, based on the total weight of the polyamide composition.

9. The polyamide composition according to claim 8, which comprises the filler in a lamellar shape in an amount of from 30% to 55% by weight, preferably from 35% to 50% by weight, and the additional filler in an amount of no higher than 5% by weight, based on the total weight of the polyamide composition.

10. The polyamide composition according to claim 8 or 9, wherein the additional filler is selected from glass fibers.

11. The polyamide composition according to any of preceding claims, which comprises at least one additive selected from UV absorber, hindered amine light stabilizer, antioxidant, lubricant, nucleating agent, colorant, release agent, anti-dripping agent, impact modifier, compatibilizing agent, plasticizer, surfactant, flame retardant, flame retardant synergist, coupling agent, antimicrobial agent and antistatic agents.

12. The polyamide composition according to claim 11 , which comprises a UV absorber in an amount of from 0.05% to 5% by weight, preferably from 0.1% to 2% by weight, based on the total weight of the polyamide composition.

13. The polyamide composition according to claim 11 or 12, which comprises a hindered amine light stabilizer, in an amount of from 0.05% to 3% by weight, preferably from 0.1% to 1% by weight, based on the total weight of the polyamide composition.

14. Use of the polyamide composition according to any of preceding claims as insulating materials in high-voltage transmission and distribution systems.

15. The use of the polyamide composition according to claim 14 in circuit breakers, reclosers and transformers.

16. Articles produced using the polyamide composition according to any of preceding claims 1 to 13.

17. The articles according to claim 16, which are articles in high-voltage transmission and distribution systems, such as circuit breakers, reclosers and transformers.