POLYAMIDE COMPOSITION

Abstract

The present invention relates to a polyamide, to a composition comprising same, and to the use thereof, and also to a molded article deriving therefrom and to a process for producing same. The polyamide is particularly suitable as hot-melt adhesive for the low-pressure and low-temperature overmolding of a heat-sensitive battery, for example a lithium-polymer battery.

Claims

1-15. (canceled)

16. A polyamide which is the product of polycondensation of an acid component and of an amine component, the acid component comprising, per mole of acid component: from 25 to 50 mol% of at least one fatty acid dimer; from 46 to 70 mol% of at least one aliphatic diacid; and from 0 to 11 mol% of at least one chain limiter; the amine component comprising, per mole of amine component: from 13 to 29 mol% of at least one aliphatic diamine; from 66 to 82 mol% of at least one cycloaliphatic diamine; and from 0 to 15 mol% of at least one polyetheramine; the polyamide comprising a —COOH/(—NH and/or —NH.sub.2) molar ratio of from 1.00 to 1.20.

17. The polyamide as claimed in claim 16, wherein the fatty acid dimer is a product of a reaction for coupling unsaturated monocarboxylic acids.

18. The polyamide as claimed in claim 16, wherein the aliphatic diacid is selected from the group consisting of saturated aliphatic dicarboxylic acids.

19. The polyamide as claimed in claim 16, wherein the chain limiter comprises monocarboxylic acids, anhydrides, monohalogenated acids, monoesters or monoisocyanates.

20. The polyamide as claimed in claim 16, wherein the aliphatic diamine comprises linear or branched, saturated aliphatic diamines.

21. The polyamide as claimed in claim 16, wherein the cycloaliphatic diamine is selected from the group consisting of bis(3,5-dialkyl-4-aminocyclohexyl)methane, bis(3,5-dialkyl-4-aminocyclohexyl)ethane, bis(3,5-dialkyl-4-aminocyclohexyl)propane, bis(3,5-dialkyl-4-aminocyclohexyl)butane, bis(3-methyl-4-aminocyclohexyl)methane (BMACM or MACM), bis(p-aminocyclohexyl)methane (PACM), isopropylidenedi(cyclohexylamine) (PACP), isophoronediamine, piperazine, aminoethylpiperazine, norbornyl methane, cyclohexylmethane, dicyclohexylpropane, di(methylcyclohexyl), di(methylcyclohexyl) propane, 1,4-cyclohexanediamine, 4,4′-diamino-dicyclohexylmethane, piperazine, cyclohexane-bis-(methylamine), isophoronediamine (IPDA), dimethylpiperazine, dipiperidylpropane, norbornanediamine, and mixtures thereof.

22. The polyamide as claimed in claim 16, wherein the polyetheramine is selected from the group consisting of polyoxyalkylenediamines with a number-average molecular weight (Mn) ranging from 200 to 4000 g/mol.

23. The polyamide as claimed in claim 16, wherein the polyamide is a product of polycondensation of an acid component and of an amine component, the acid component comprising, per mole of acid component: from 35 to 50 mol% of at least one fatty acid dimer; from 52 to 70 mol% of at least one aliphatic diacid; and from 2 to 5 mol% of at least one chain limiter; the amine component comprising, per mole of amine component: from 19 to 23 mol% of at least one aliphatic diamine, which is ethylenediamine; from 72 to 76 mol% of at least one cycloaliphatic diamine, which is piperazine; and from 3 to 5 mol% of at least one polyetheramine, which is polyoxypropylenediamine; the polyamide comprising a —COOH/(—NH and/or —NH.sub.2) molar ratio of from 1.07 to 1.11.

24. A composition comprising the polyamide as defined in claim 16.

25. The composition as claimed in claim 24, comprising at least one additive selected from the group consisting of fillers, antioxidants or stabilizers, mold-release agents, adhesion promoters, pigments and mixtures thereof.

26. The composition as claimed in claim 24, wherein the polyamide composition has a viscosity of 10,000 mPa.s or less at a temperature of 150° C.

27. The composition as claimed in claim 24, wherein the polyamide composition has a softening point of 150° C. or less.

28. A molded article comprising an insert and the polyamide composition as claimed in claim 24, said insert being overmolded at least in part by the polyamide composition.

29. A process for producing a molded article, comprising the following steps: providing a mold; inserting an insert into the mold; heating a polyamide composition to a temperature of 150° C. or less, in order to obtain a molten polyamide composition; injecting the molten polyamide composition at a pressure of from 0.5 × 10.sup.5 to 50 × 10.sup.5 Pa; cooling the injected polyamide composition; optionally removing the obtained molded article from the mold.

30. A hot-melt adhesive for low-pressure overmolding of a heat-sensitive battery comprising the polyamide of claim 16.

31. The polyamide as claimed in claim 17, wherein the fatty acid dimer is a product of a reaction for coupling unsaturated monocarboxylic acids, wherein the unsaturated monocarboxylic acids are selected from the group consisting of unsaturated monocarboxylic acids comprising from 10 to 22 carbon atoms.

32. The polyamide as claimed in claim 18, wherein the aliphatic diacid is selected from the group consisting of succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, brassylic acid, tetradecanedioic acid, pentadecanedioic acid, thapsic acid, and mixtures thereof.

33. The polyamide as claimed in claim 19, wherein the chain limiter comprises a monocarboxylic acid.

34. The polyamide as claimed in claim 20, wherein the aliphatic diamine is selected from the group consisting of ethylenediamine, propanediamine, butanediamine, pentanediamine, hexanediamine, decanediamine and mixtures thereof.

Description

DETAILED DESCRIPTION

[0053] The invention is now described in more detail and in a non-limiting way in the description which follows.

[0054] For the purposes of the present invention, the term “hot-melt” is intended to mean the ability of the polyamide to melt under the effect of heat.

[0055] In the description, unless otherwise indicated, all the percentages indicated are molar percentages.

[0056] For the purposes of the present invention, the expression “between... and...” or “from... to...” is intended to mean that the limits are included in the range described.

Polyamide

[0057] In a first aspect, the present invention relates to a polyamide which is the product of the polycondensation of an acid component and of an amine component, [0058] the acid component comprising, per mole of acid component: [0059] from 25 to 50 mol%, preferentially from 30 to 50 mol%, very preferentially from 35 to 50 mol%, of at least one fatty acid dimer; [0060] from 46 to 70 mol%, preferentially 49 to 70 mol%, very preferentially from 52 to 70 mol%, of at least one aliphatic diacid; [0061] from 0 to 11 mol%, preferentially 0 to 10 mol%, very preferentially from 2 to 5 mol%, of at least one chain limiter; [0062] the amine component comprising, per mole of amine component: [0063] from 13 to 29 mol%, preferentially 16 to 26 mol%, very preferentially from 19 to 23 mol%, of at least one aliphatic diamine; [0064] from 66 to 82 mol%, preferentially 69 to 79 mol%, very preferentially from 72 to 76 mol%, of at least one cycloaliphatic diamine; and [0065] from 0 to 15 mol%, preferentially 0 to 10 mol%, very preferentially from 3 to 5 mol%, of at least one polyetheramine; [0066] the polyamide comprising a —COOH/(—NH and/or —NH.sub.2) molar ratio of from 1.00 to 1.20, preferentially from 1.04 to 1.15, very preferentially from 1.07 to 1.11.

[0067] The —COOH/(—NH and/or —NH.sub.2) molar ratio between the carboxylic functions and the primary and/or secondary amine functions, the contents of which are expressed in mg KOH/g, is determined by potentiometry.

[0068] The polyamide can be obtained by polycondensation of the acid component and of the amine component according to a conventional process. Depending on the process used, the polyamide may be a random polymer or a block polymer, preferentially a random polymer.

Fatty Acid Dimers

[0069] Fatty acid dimers are polymerized fatty acids which denote compounds produced from coupling reactions of unsaturated fatty acids which result in mixtures of products bearing two acid functions. The fatty acid dimer can be obtained by a dimerization reaction of unsaturated monocarboxylic acids. The fatty acid dimer is thus the reaction product of the coupling of unsaturated monocarboxylic acids. The unsaturated monocarboxylic acids can be chosen from unsaturated monocarboxylic acids comprising from 10 to 22 carbon atoms (C.sub.10 to C.sub.22); preferentially from unsaturated monocarboxylic acids comprising from 12 to 18 carbon atoms (C.sub.12 to C.sub.18); very preferentially from unsaturated monocarboxylic acids comprising from 16 to 18 carbon atoms (C.sub.16 to C.sub.18).

[0070] The fatty acid dimers can be obtained, from unsaturated monocarboxylic acids, by well-known processes, such as described, for example, in patent applications US 2 793 219 and US 2 955 121. The unsaturated monocarboxylic acids can be chosen from oleic acid, linoleic acid, linolenic acid and their mixtures.

[0071] According to whether they are crude or distilled, the fatty acid dimers exhibit a content of dimers ranging from 75% to more than 98%, as a mixture with greater or lesser amounts of monomers, trimers and higher homologues, according to the commercial grade.

[0072] Fatty acid dimers are available commercially under the names Radiacid® from Oleon, Pripol® from Croda or Unydime® from Kraton.

Aliphatic Diacids

[0073] Throughout the description, the expressions “diacid”, “carboxylic diacid” and “dicarboxylic acid” denote the same product.

[0074] The aliphatic diacid can be chosen from saturated aliphatic dicarboxylic acids; preferentially from linear or branched, saturated aliphatic dicarboxylic acids; very preferentially from among the saturated aliphatic dicarboxylic acids having from 4 to 22 carbon atoms (C.sub.4-C.sub.22); more preferentially from succinic acid (butanedioic acid) (C.sub.4), glutaric acid (pentanedioic acid) (C.sub.5), adipic acid (hexanedioic acid) (C.sub.6), pimelic acid (heptanedioic acid) (C.sub.7), suberic acid (octanedioic acid) (C.sub.8), azelaic acid (nonanedioic acid) (C.sub.9), sebacic acid (decanedioic acid) (C.sub.10), undecanedioic acid (C.sub.11), dodecanedioic acid (C.sub.12), brassylic acid (tridecanedoic acid) (C.sub.13), tetradecanedioic acid (C.sub.14), pentadecanedioic acid (C.sub.15), thapsic acid (hexadecanedioic acid) (C.sub.16), and mixtures thereof; even more preferentially from azelaic acid (C.sub.9), sebacic acid (C.sub.10), dodecanedioic acid (C.sub.12) and mixtures thereof.

Chain Limiters

[0075] The polyamide according to the invention is synthesized in a conventional manner, if necessary in the presence of at least one chain limiter.

[0076] The chain limiter can be chosen from monocarboxylic acids, anhydrides (for example phthalic anhydride), monohalogenated acids, monoesters or monoisocyanates; preferentially, the chain limiter is a monocarboxylic acid; very preferentially, the chain limiter is chosen from aliphatic monocarboxylic acids, alicyclic acids, aromatic monocarboxylic acids and mixtures thereof; more preferentially, the chain limiter is an aliphatic monocarboxylic acid. The monocarboxylic acid can be an aliphatic monocarboxylic acid chosen from acetic acid, propionic acid, lactic acid, valeric acid, caproic acid, capric acid, lauric acid, tridecylic acid, myristic acid, palmitic acid, stearic acid, pivalic acid, isobutyric acid or their mixtures. The alicyclic acid can be a cyclohexanecarboxylic acid. The aromatic monocarboxylic acid can be chosen from benzoic acid, toluic acid, α-naphthalenecarboxylic acid, β-naphthalenecarboxylic acid, methylnaphthalenecarboxylic acid, phenylacetic acid and their mixtures.

[0077] Chain limiters are commercially available under the name Radiacid® from Oleon.

Aliphatic Diamines

[0078] The aliphatic diamine can be chosen from linear or branched, saturated aliphatic diamines; preferentially from saturated linear aliphatic diamines of formula H.sub.2N—(CH.sub.2).sub.n—NH.sub.2 with n between 2 and 12; very preferentially from ethylenediamine, propanediamine, butanediamine, pentanediamine, hexanediamine, decanediamine and mixtures thereof; more preferentially, the aliphatic diamine is ethylenediamine. The advantageous branched aliphatic diamines include 2-methylpentamethylenediamine, 1,3-pentanediamine, methylpentanediamine and trimethylhexamethylenediamine.

Cycloaliphatic Diamines

[0079] The cycloaliphatic diamine can be chosen from bis(3,5-dialkyl-4-aminocyclohexyl)methane, bis(3,5-dialkyl-4-aminocyclohexyl)ethane, bis(3,5-dialkyl-4-aminocyclohexyl)propane, bis(3,5-dialkyl-4-aminocyclohexyl)butane, bis(3-methyl-4-aminocyclohexyl)methane (BMACM or MACM), bis(p-aminocyclohexyl)methane (PACM), isopropylidenedi(cyclohexylamine) (PACP), isophoronediamine, piperazine, aminoethylpiperazine, dimethylpiperazine, 4,4′-trimethylenedipiperidine, 1,4-cyclohexanediamine, a cycloaliphatic diamine having a carbon-based backbone (for example norbornylmethane, cyclohexylmethane, dicyclohexylpropane, di(methylcyclohexyl), di(methylcyclohexyl)propane) and mixtures thereof; preferentially, the cycloaliphatic diamine is piperazine.

[0080] A non-exhaustive list of these cycloaliphatic diamines is given in the publication “Cycloaliphatic Amines” (Encyclopedia of Chemical Technology, Kirk-Othmer, 4th Edition (1992), pp. 386-405).

Polyetheramines

[0081] The polyetheramine can be chosen from polyoxyalkylene diamines with a number-average molecular weight (Mn) ranging from 200 to 4000 g/mol. Preferably, it concerns a polyoxyalkylene chain bearing an amine group at the chain end. The polyetheramine can be chosen from polyoxypropylenediamines, polyoxybutylenediamines, bis(diaminopropyl)polytetrahydrofuran and mixtures thereof; very preferentially, the polyetheramine is polyoxypropylenediamine. Polyetheramines are available commercially under the Jeffamine® name from Huntsman and the Baxxodur® name from BASF.

[0082] In one particular embodiment, the polyamide is the product of the polycondensation of an acid component and of an amine component, [0083] the acid component comprising, per mole of acid component: [0084] from 35 to 50% of at least one fatty acid dimer; [0085] from 52 to 70% of at least one aliphatic diacid; [0086] from 2 to 5% of at least one chain limiter; [0087] the amine component comprising, per mole of amine component: [0088] from 19 to 23% of at least one aliphatic diamine which is ethylenediamine (C.sub.2); [0089] from 72 to 76% of at least one cycloaliphatic diamine which is piperazine; and [0090] from 3 to 5% of at least one polyetheramine which is polyoxypropylenediamine; [0091] the polyamide comprising a —COOH/(—NH + —NH.sub.2) molar ratio of from 1.07 to 1.11.

[0092] The polyamide can be prepared on the basis of a conventional process. For example, all of the reagents are charged to a suitable reactor equipped with a mixer and then heated under nitrogen at a temperature of between 190 to 250° C. for 20 to 500 min (until the volume of distillate no longer increases under nitrogen flushing). Then, the reactor is placed under vacuum at a pressure of between 5 ×10.sup.5 and 500 ×10.sup.5 mPa (5 and 500 mbar) and maintained under these conditions until the desired viscosity is obtained.

Composition

[0093] In a second aspect, the present invention relates to a composition comprising a polyamide as defined above.

[0094] The polyamide composition can comprise, besides the polyamide obtained by polycondensation of the acid component and of the amine component, at least one additive.

[0095] The additive can be chosen from fillers, antioxidants or stabilizers, mold-release agents, adhesion promoters, pigments and their mixtures.

[0096] The adhesive composition may comprise from 0 to 5%, preferentially from 0.5 to 5%, of additives, relative to the weight of the polyamide.

[0097] In one embodiment, the polyamide composition is free of tackifying resins. The polyamide composition can have a viscosity of 10 000 mPa.s or less; preferentially from 3000 to 6000 mPa.s, at a temperature of 150° C. The viscosity is measured according to Standard ASTM D3236, using Brookfield equipment and an SC4-A27 spindle.

[0098] The polyamide composition may comprise a softening point (softening temperature) of 150° C. or less; preferentially from 100 to 145° C.; very preferentially from 115 to 140° C. The softening point can be measured according to Standard ASTM D3461, using “Cup&Ball” equipment and a temperature gradient of 2° C./min.

[0099] The polyamide composition may also comprise a tensile strength of 1.5 to 3.1 MPa. The tensile strength can be measured according to Standard ISO 527 by preparing test specimens of 1A type and by tensioning these test specimens using a dynamometer, at a rate of 50 mm/min.

[0100] The polyamide composition may also comprise an elongation at break of 70 to 170%. The elongation at break can be measured according to Standard ISO 527 by preparing test specimens of 1A type and by tensioning these test specimens using a dynamometer, at a rate of 50 mm/min.

[0101] The polyamide composition may also comprise a Shore A hardness of 60 to 80. The Shore A hardness can be measured according to Standard ISO 868, by using a durometer with recording of values immediately and after 15 sec. The polyamide composition may also comprise a Shore D hardness of 15 to 30%. The Shore D hardness can be measured according to Standard ISO 868, by using a durometer with recording of values immediately and after 15 sec.

Molded Article

[0102] In a third aspect, the present invention relates to a molded article comprising an insert and the polyamide composition described above, said insert being overmolded at least in part by the polyamide composition. Said insert can be a battery, preferentially a heat-sensitive battery, very preferentially a lithium-polymer battery.

[0103] The molded article can additionally comprise a substrate. The substrate can be obtained from materials chosen from plastic, metal, glass, ceramic or any other appropriate substance, preferentially plastic; very preferentially, the plastic is a thermoplastic polymer. For example, the thermoplastic polymer can be acrylonitrile-butadiene-styrene (ABS).

[0104] In one embodiment, the polyamide composition can be injected between the insert and the substrate, in order to ensure the adhesion of the two parts together. In this configuration, the substrate forms the exterior casing of the molded article. In another embodiment, the polyamide composition can be injected around the insert, and the substrate, if present. In this configuration, the overmolded polyamide composition forms the exterior casing of the molded article. Any alternative configuration can be envisaged.

[0105] The insert, around which the polyamide composition is overmolded, can be any suitable insert, in particular a battery, in particular a rechargeable battery, for example the batteries used in electronic devices such as telephones and laptops. In one preferred embodiment, the insert is a polymer-lithium battery. The molded article can be obtained from any suitable molding process, for example by extrusion, cast molding, injection molding, compression molding or transfer molding. In one preferred embodiment, the molded article is obtained by a process by low-temperature and low-pressure injection, such as described below.

[0106] Process for the production of a molded article:

[0107] In a third aspect, the present invention relates to a process for producing a molded article.

[0108] The process by low-temperature and low-pressure injection can comprise the following steps: [0109] providing a mold; [0110] inserting the parts to be adhesively bonded (insert) into the mold, preferentially a lithium-polymer battery; [0111] heating the polyamide composition to a temperature of 150° C. or less, preferentially from 120° C. to 150° C., in order to obtain a molten polyamide composition; [0112] injecting the molten polyamide composition at a pressure of from 0.5 × 10.sup.5 to 50 ×10.sup.5 Pa, preferentially from 2 × 10.sup.5 to 40 × 10.sup.5 Pa; [0113] cooling the injected polyamide composition; [0114] optionally removing the obtained molded article from the mold.

[0115] Depending on the configuration, the mold can form an integral part of the molded article (for example if the polyamide composition is injected between the insert and the substrate) or can be removed after the overmolding of the polyamide composition.

[0116] The use of the polyamide composition for obtaining molded articles is particularly advantageous in that it can be molded at low pressure, in that it exhibits satisfactory flow properties at molding temperatures of 150° C. or less and in that it exhibits a satisfactory temperature strength in the molded state. These properties are suitable for the molding of electronic devices which are sensitive to high temperatures and which generate heat, in particular lithium-polymer batteries.

Use

[0117] In a fourth aspect, the present invention relates to the use of the polyamide, or of the polyamide composition comprising same, as described above, as a hot-melt adhesive for the low-pressure overmolding of a heat-sensitive battery, preferentially a lithium-polymer battery, and optionally its substrate.

EXAMPLE

[0118] The following example illustrates the invention without limiting it.

Materials Used

[0119] Fatty acid dimer: Radiacid 0970® (fatty acid dimer, refined, high purity) from Oleon; [0120] Fatty monoacid: Radiacid 0944® (fatty monoacid) from Oleon; [0121] Fatty diacid 1: sebacic acid; [0122] Fatty diacid 2: dodecanedioic acid; [0123] Fatty diacid 3: azelaic acid; [0124] Aliphatic diamine: ethylenediamine; [0125] Cyclic diamine: piperazine; [0126] Polyetheramine: Jeffamine D2000® (polyoxypropylenediamine) from Huntsman; [0127] Fillers: liquid dye based on carbon black (2.5 - 10%); [0128] Mold-release agent: Ethylene bis-Stearamide.

Process for the Preparation of the Polyamide

[0129] All of the reactants are charged in a suitable mixer-equipped reactor and then heated under nitrogen for 4 h 30 up to a temperature of 225° C. Subsequently, the reactor is maintained at this temperature for 2 h 30 and then placed under vacuum at a pressure of between 1000 and 5000 Pa for 1 h.

Polyamide

[0130] TABLE-US-00001 P1 P2 P3 P4 Acid component (mol%) Fatty acid dimers 43 43 43 41 Fatty diacid 1 44 54 - 28 Fatty diacid 2 10 - - 28 Fatty diacid 3 - - 54 - Fatty monoacid 3 3 3 3 Amine component (mol%) Aliphatic diamine (mol%) 21 22 21 21 Cycloaliphatic diamine 74 74 74 74 Polyetheramine 5 5 5 5

Polyamide Composition

[0131] TABLE-US-00002 Compositions 1 2 3 4 Polyamide P1 P2 P3 P4 Charge (% by mass) 1 1 1 1 Mold-release agent (% by mass) 1 1 1 1 Ratio acid (COOH):amine (primary and/or secondary) end groups 1.09 1.09 1.09 1.09 End group Acid Acid Acid Acid

[0132] The mass percentage of filler and of molding agent is expressed as a function of the mass of polyamide.

Results

[0133] TABLE-US-00003 Compositions 1 2 3 4 Viscosity (150° C.) (mPa.s) 5820 5970 5260 6450 Softening point (°C) 121 126 138 119 Tensile strength (MPa) 2.4 2.9 1.7 2.7 Elongation at break (%) 118 88 96 155 Shore A hardness 74 78 64 78 Shore D hardness 16 18 11 17

[0134] Compositions 1 to 4, respectively comprising the polyamides P1 to P4, have a viscosity and a softening point which are particularly suitable for their use as hot-melt adhesive in processes for the overmolding of heat-sensitive inserts, in particular lithium-polymer batteries, and make it possible to obtain molded articles with satisfactory mechanical and thermal properties.