PROCESS FOR TREATING A MATERIAL CHOSEN FROM AMONG A POLYAMIDE, A POLYESTER AND A POLY(METH)ACRYLATE

Abstract

This invention relates to a treatment process for a material chosen from among a polyamide, a polyester and a poly(meth)acrylate.

According to the invention, this process comprises a step in which contact is made between this material and a polar organic solvent in a supercritical fluid.

This invention also relates to a process for manufacturing a part from a material chosen from among a polyamide, a polyester and a poly(meth)acrylate in a divided form.

Finally, the invention relates to use of the material treated by the treatment process and to use of the part manufactured by the manufacturing process in the low voltage, medium voltage or high voltage electrical industry.

Claims

1. A process for the treatment of a material of a component of an electrical appliance to impart improved moisture resistance properties to the material, the material being chosen from among a polyamide, a polyester and a poly(meth)acrylate, the process comprising a first step in which contact is made between the material and a polar organic solvent in a first supercritical fluid.

2. A process according to claim 1, wherein the material is a composite material containing fillers.

3. A process according to claim 2, wherein the fillers are silica fillers.

4. A process according to claim 2, wherein the fillers are in the form of particles, fibers or in the form of mixtures thereof.

5. A process according to claim 2, wherein the proportion by mass of the fillers is greater than or equal to 20% m, advantageously between 25% m and 60% m and, preferably, between 30% m and 50% m, relative to the total mass of the composite material.

6. A process according to claim 1, wherein the polar organic solvent is a protic polar organic solvent, advantageously an alcohol and, preferably, methanol or ethanol.

7. A process according to claim 1, wherein the polar organic solvent is an aprotic polar organic solvent, advantageously chosen from among a ketone, an ether and a chloroalkane, the ketone and the ether being, preferably and respectively, acetone and tetrahydrofuran.

8. A process according claim 1, wherein the first supercritical fluid is chosen from among carbon dioxide, methane, propane, butane, dinitrogen and dimethyl ether and, advantageously, from among carbon dioxide and butane.

9. A process according to claim 1, wherein the first step is carried out at a temperature of between 80° C. and 200° C. and at a pressure of supercritical fluid of between 100 bar and 400 bar.

10. A process according to claim 1, further comprising a second step of bringing the material as obtained at the end of the first step into contact in a second supercritical fluid with one or several compounds soluble in the second supercritical fluid and each satisfying the following formula (I):
R—(N═C═O).sub.n  (I) wherein n is equal to 1 or 2, and R is chosen from among a saturated or unsaturated, linear or branched, aliphatic hydrocarbon group comprising at least 2 carbon atoms, and a saturated or unsaturated, possibly branched, cyclic aliphatic hydrocarbon group comprising at least 3 carbon atoms, R possibly also comprising a free-radically polymerizable ethylenically unsaturated group such as a vinyl, allyl or (meth)acrylate group.

11. A process according to claim 10, wherein, during the second step, the material is brought into contact with the compound(s) of formula (I) in the second supercritical fluid in the presence of an aprotic polar organic solvent, advantageously chosen from among a ketone, an ether and a chloroalkane, the ketone and the ether being, preferably and respectively, acetone and tetrahydrofuran.

12. A process according to claim 10, wherein the second supercritical fluid is chosen from among carbon dioxide, methane, propane, butane, dinitrogen and dimethyl ether and is, advantageously, carbon dioxide.

13. A process according to claim 10, wherein the second step is carried out at a temperature of between 60° C. and 200° C. and at a pressure of second supercritical fluid of between 35 bar and 400 bar.

14. A process according to claim 10, further comprising, after the second step and in the case in which one of the compounds of formula (I) comprises a free-radically polymerizable ethylenically unsaturated group, a third step consisting of bringing the material as obtained at the end of the second step into contact, in a third supercritical fluid, with a mixture comprising a radical polymerization initiator and one or several free-radically polymerizable ethylenically unsaturated monomers, the radical polymerization initiator and the monomer(s) each being soluble in the third supercritical fluid.

15. A process according to claim 14, wherein the free-radically polymerizable ethylenically unsaturated monomer(s) are chosen from among (meth)acrylate monomers.

16. A process according to claim 14, wherein the third supercritical fluid is chosen from among carbon dioxide, methane, propane, butane, dinitrogen and dimethyl ether and is, advantageously, carbon dioxide.

17. A process according to claim 14, wherein the third step is carried out at a temperature of between 50° C. and 100° C. and at a pressure of third supercritical fluid of between 100 bar and 350 bar.

18. A process according to claim 10, wherein the first and second supercritical fluids and possibly the third supercritical fluids are identical and are advantageously composed of carbon dioxide.

19. A process according to claim 10, wherein the first and second steps and possibly the third step are carried out in the same reactor.

20. A process according to claim 1, wherein the polyamide(s) of the material are chosen from among PA 6, PA 6.6, PA 6.10, PA 6.12 and polyphthalamides and, preferably, among PA 6.6 and PA 6.T.

21. A process according to claim 1, wherein the material is in a divided form or in the form of a part, the part possibly being a new part or a part in maintenance.

22. A process for manufacturing a part of an electrical appliance from a material chosen from among a polyamide, a polyester and a poly(meth)acrylate, this material being in a divided form, this process comprising the following successive steps (i) and (ii): (i) treatment of the material in divided form by application of the process according to claim 1, and (ii) forming of the treated material in divided form as obtained at the end of step (i).

23. A method of using the material treated by the process according to claim 1 in the low, medium or high voltage electrical industry.

24. A method according to claim 23, wherein the material is used in one or several electrically insulating components of an electrical appliance such as a transformer, a line or a busbar for the transmission or distribution of electricity, or a breaking device such as a switch, a circuit breaker or a combined fuse-switch or an isolating switch, for example an earthing isolator.

25. A method according to claim 24, wherein the breaking appliance comprises a sealed chamber in which there are, in addition to the one or more electrical insulating components, electrical components and a gaseous medium electrically insulating and extinguishing electric arcs that could form inside this sealed chamber, the gaseous medium preferably including air, a fluoronitrile, a fluoroketone, a hydrofluoroolefine or a mixture thereof.

26. A method of using the part manufactured by the process according to claim 22 in the low, medium or high voltage electrical industry.

Description

DETAILED PRESENTATION OF PARTICULAR EMBODIMENTS

1. Operational Protocols of Experimental Tests

[0116] The samples are in the form of type A test pieces complying with standard ISO 3167 formed by a composite material composed of a PA 6.6 comprising 50% m of glass fibers and marketed by the Solvay Company under the tradename Technyl® A 218 V50 Natural.

[0117] Each treatment was carried out on a batch of 10 test pieces.

1.1. Process Only Including Step (1)

[0118] The batch of 10 test pieces in example A was not treated in any way and consequently corresponds to a reference example.

[0119] Each batch of examples B and C, which also correspond to reference examples, was placed in the internal volume of a reactor heated to temperature T1 and within which each batch was brought into contact, for a duration t1, with a supercritical fluid SC1 introduced and maintained, for the duration t1, at a pressure P1.

[0120] Each batch of examples 1.1 to 1.3, which correspond to three examples according to the invention, was placed with 10 ml of a polar organic solvent in the internal volume of a reactor heated to temperature T1. The assembly was brought into contact, for a duration t1, with a supercritical fluid SC1 introduced and maintained, for the duration t1, at a pressure P1.

[0121] The nature of the supercritical fluid SC1, the polar organic solvent if there is one, and the operational parameters T1, P1 and t1 are given in Table 1 below.

TABLE-US-00001 TABLE 1 Examples SC1 Solvent T1(° C.) P1(bar) T1(h) A — — — — — B CO.sub.2 — 160 300 1 C butane — 170 110 1 1.1 CO.sub.2 ethanol 160 300 3 1.2 CO.sub.2 acetone 160 300 3 1.3 CO.sub.2 methanol 160 300 3

1.2. Process Including Steps (1) and (2):

[0122] The batch of 10 samples in example D, which corresponds to a reference example, was placed in the internal volume of a reactor heated to temperature T1 and within which this batch was brought into contact, for a duration t1, with a supercritical fluid SC1 introduced and maintained, for the duration t1, at a pressure P1.

[0123] After the duration t1 and after decompression, a dropper bottle containing a mixture formed from: [0124] 1.06 g of n-octadecyl isocyanate (n-C.sub.18H.sub.37NCO), [0125] 1.01 g of 1.4-diazacyclo[2.2.2]octane (DABCO) as catalyst, and [0126] 2 ml of acetone,
was introduced into the internal volume of the reactor that was then heated to a temperature T2 to bring the assembly into contact, for a duration t2, with a supercritical fluid SC2 introduced and maintained, for the duration t2, at a pressure P2. [0127] Each batch of examples 2.1 and 2.2, which correspond to two examples conforming with the invention, was placed with a volume of: [0128] 5 ml of ethanol for example 2.1, and [0129] 10 ml of ethanol for example 2.2,
in the internal volume of a reactor heated to a temperature T1 to bring the assembly into contact, for a duration t1, with a supercritical fluid SC1 introduced and maintained, for the duration t1, at a pressure P1.

[0130] After the duration t1 and after decompression, a dropper bottle containing: [0131] for example 2.1, a mixture formed from 1 g of n-octadecyl isocyanate (n-C.sub.18H.sub.37NCO) and 1 g of DABCO in 1 ml of acetone, and [0132] for example 2.2, a mixture formed from 1.6 g of cyclohexyl isocyanate (C.sub.7H.sub.11NCO) and 0.39 g of 1,6-hexamethylene diisocyanate (OCN(C.sub.6H.sub.12)NCO) in 3 g of acetone,
was introduced into the internal volume of the reactor that was then heated to a temperature T2 to bring the assembly into contact, for a duration t2, with a supercritical fluid SC2 introduced and maintained, for the duration t2, at a pressure P2.

[0133] The nature of the supercritical fluids SC1 and SC2, of the polar organic solvents, and the operational parameters T1, T2, P1, P2, t1 and t2 are given in Table 2 below.

TABLE-US-00002 TABLE 2 Examples D 2.1 2.2 Step (1): CO.sub.2/— CO.sub.2/ethanol butane/ethanol SC/solvent 100/300/2 160/300/2 170/115/1 T1(° C.)/P1(bar)/ t1(h) Step (2): n-C.sub.18H.sub.32NCO n-C.sub.18H.sub.32NCO C.sub.2H.sub.11NCO + Compound (I) CO.sub.2/acetone CO.sub.2/acetone OCN(C.sub.6H.sub.12)NCO SC2/Solvent 100/300/1 100/300/1 CO.sub.2/acetone T2(° C.)/P2(bar)/ 100/300/1 t2(h)

[0134] 1.3. Process including steps (1) to (3): [0135] The batch in example E, which corresponds to a reference example, was placed in the internal volume of a reactor heated to temperature T1 and within which this batch was brought into contact, for a duration t1, with a supercritical fluid SC1 introduced and maintained, for the duration t1, at a pressure P1.

[0136] After the duration t1 and after decompression, a dropper bottle containing: [0137] a mixture composed of 1.09 g of 2-isocyanatoethyl methacrylate ((C.sub.6H.sub.9O.sub.2)NCO) and 1 g of DABCO
was placed in the internal volume of the reactor that was then heated to a temperature T2 to bring the assembly into contact, for a duration t2, with a supercritical fluid SC2 introduced and maintained, for the duration t2, at a pressure P2.

[0138] After the duration t2 and after decompression, a dropper bottle containing: [0139] 2 ml of ethyl methacrylate (C.sub.6H.sub.10O.sub.2) and 1 g of azobisisobutyronitrile (AlBN)
was placed in the internal volume of the reactor that was then heated to a temperature T3 to bring the assembly into contact, for a duration t3, with a supercritical fluid SC3 introduced and maintained, for the duration t3, at a pressure P3. [0140] The same operating protocol as that described above for the batch in example E was applied for the batch in example 3.1, except for step (1) that was performed by placing the batch of 10 test pieces with 15 ml of polar organic solvent in the internal volume of the reactor at a temperature T1 to bring the assembly into contact, for a duration t1, with a supercritical fluid SC1 introduced and maintained, for the duration t1, at a pressure P1.

[0141] The nature of the supercritical fluids SC1, SC2 and SC3, of the polar organic solvents, and the operational parameters T1, T2, T3, P1, P2, P3, t1, t2 and t3 are given in Table 3 below.

TABLE-US-00003 TABLE 3 Examples E 3.1 Step (1): CO.sub.2/— CO.sub.2/ethanol SC/solvent 160/300/2 160/300/2 T1(° C.)/P1(bar)/t1(h) Step (2): (C.sub.6H.sub.9O.sub.2)NCO (C.sub.6H.sub.9O.sub.2)NCO Compound (I) CO.sub.2/— CO.sub.2 SC2/Solvent 100/300/1 100/300/1 T2(° C.)/P2(bar)/t2(h) Step (3): CO.sub.2/C.sub.6H.sub.12O.sub.2 CO.sub.2/C.sub.6H.sub.12O.sub.2 SC3/Monomer 100/300/1 100/300/1 T3(° C.)/P3(bar)/t3(h)

2. Evaluation of the Properties of the Treated Composite Materials

2.1. Evaluation of the Water Intake

[0142] The “water intake” represents the quantity of water that can be absorbed by a material. It can be expressed by the ratio of the increase in the mass of the material after immersion in water, relative to its initial mass.

[0143] The evaluation of the water intake of a given material consists of placing a sample of material under given relative humidity conditions for a predefined duration. The material then hydrates, increasing the mass of the sample from an initial value m to a final value (m+δm). The water intake, expressed as a %, is therefore defined by the ratio δm/m.

[0144] In this case, each batch of test pieces treated in accordance with the protocols described above was weighed to determine the initial mass m.

[0145] Each batch was then placed in an atmosphere at 70° C. with saturated humidity (relative humidity equal to 100%) for 1000 h that is sufficiently long to saturate the tested test pieces. After 1000 h, each batch was weighed once again to determine the final mass m+δm.

[0146] The water intake results are summarised in Table 4 below.

2.2. Evaluation of Mechanical Properties

[0147] The mechanical properties were determined by tension tests performed at 23° C. on each batch of test pieces as obtained in paragraphs 1.1. and 1.2. above.

[0148] The values of the ultimate stress (in MPa) determined according to standard ISO 527-1:2012 are also given in Table 4 below.

TABLE-US-00004 TABLE 4 Examples Water intake (%) Ultimate stress (MPa) A 3.9 143 B 3.7 141 C 3.4 151 1.1 2.1 150 1.2 2.3 152 1.3 2.1 150 D 3.3 139 2.1 2.2 153 2.2 2.7 150

[0149] The results in Table 4 clearly show the particularly beneficial effect of the treatment process according to the invention on water intake and the mechanical properties of a composite material based on a polyamide and comprising silica fillers.

[0150] In particular, with reference firstly to examples A and B, and secondly to examples 1.1 to 1.3, it is observed that water intake values of 3.9% obtained without any treatment (example A) and 3.7% obtained with a step (1) performed in supercritical CO.sub.2 alone (example B) drop to values of between 2.1% and 2.3%, when step (1) is performed in supercritical CO.sub.2 in the presence of a polar organic solvent such as ethanol, acetone or methanol (examples 1.1 to 1.3). Similarly, an improvement of mechanical properties is observed, the ultimate stress values of 143 MPa and 141 MPa in examples A and B changing to values between 150 MP and 152 MPa for examples 1.1 to 1.3 conforming with the invention.

[0151] This improvement is particularly significant if the reference values A and B are compared with example 2.1, which uses a treatment process comprising a step (1) performed in supercritical CO.sub.2 in the presence of ethanol and a step (2) performed in supercritical CO.sub.2 and in the presence of an isocyanate.

[0152] The comparison of water intake and ultimate stress values for examples 1.1 and 2.1 demonstrates that water intake values are maintained and that mechanical properties are improved with the implementation of a step (2) complementary to step (1).