CHEMICAL MODIFICATION PROCESS FOR A POLYMER COMPONENT

Abstract

A chemical modification process for a polymer component comprising at least one polymer comprising, as reactive groups, amine groups and/or hydroxyl groups, the process comprising a step of covalent reaction between some or all of the reactive groups and at least one functional compound comprising at least one group able to react in a covalent manner with said reactive groups, the functional compound(s) being selected from epoxide compounds, anhydride compounds, acyl halide compounds, silyl ether compounds and mixtures thereof, characterised in that the covalent reaction step is carried out in the presence of at least one supercritical fluid.

Claims

1.-16. (canceled)

17. Chemical modification process for a polymer component comprising at least one polymer comprising, as reactive groups, amine groups and/or hydroxyl groups, said process comprising a step of covalent reaction between some or all of the reactive groups and at least one functional compound comprising at least one group able to react in a covalent manner with said reactive groups, the functional compound(s) being selected from epoxide compounds, anhydride compounds, acyl halide compounds, silyl ether compounds and mixtures thereof, wherein the covalent reaction step is carried out in the presence of at least one supercritical fluid.

18. Process according to claim 17, wherein the supercritical fluid is supercritical CO.sub.2.

19. Process according to claim 17, wherein the polymer component is a component comprising one or more polyamides.

20. Process according to claim 17, wherein the polymer component is a polyamide-12 component.

21. Process according to claim 17, wherein the functional compound(s) are non-polymer compounds.

22. Process according to claim 17, wherein the functional compound(s) are epoxide compounds.

23. Process according to claim 17, wherein the functional compound(s) are epoxide compounds comprising at least one vinyl group.

24. Process according to claim 17, wherein the functional compound(s) further comprise at least one group capable of conferring to the polymer component a given property or improving a given property of the polymer component.

25. Process according to claim 17, wherein the reaction step is carried out in the presence of at least one cosolvent.

26. Process according to claim 17, wherein the reaction step includes the following operations: an operation of placing, in a reactor, the polymer component, at least one functional compound, optionally at least one cosolvent and optionally at least one catalyst; an operation of introducing CO.sub.2 into the reactor; an operation of pressurising and heating the reactor to a temperature greater than the critical temperature of CO.sub.2 and to a pressure greater than the critical pressure of CO.sub.2, this temperature and this pressure being maintained until completion of the reaction.

27. Process according to claim 17, comprising, after or simultaneously with the reaction step such as defined in claim 17, another step of covalent reaction between some or all of the residues of the functional compounds and at least one second compound, this step being carried out in the presence of at least one supercritical fluid.

28. Process according to claim 27, wherein the residue(s) comprise, as group(s) capable of reacting with at least one group of the second compound, a vinyl group.

29. Process according to claim 27, wherein the second compound comprises at least one vinyl group and at least one group capable of conferring or improving a given property to the polymer component.

30. Process according to claim 28, successively comprising: a step of covalent reaction between some or all of the reactive groups of the polymer(s) of the polymer component and at least one functional compound comprising at least one group able to react in a covalent manner with said reactive groups, the functional compound(s) being selected from epoxide compounds, anhydride compounds, acyl halide compounds, silyl ether compounds and mixtures thereof, the functional compound(s) further comprising at least one vinyl group, whereby the result is a polymer component bonded, in a covalent manner, to residues of the functional compound; from vinyl groups of the residues of the functional compound, a step of polymerising a second compound comprising at least one vinyl group, said reaction step and said polymerisation step being carried out in the presence of at least one supercritical fluid.

31. Process according to claim 30, wherein: the reactive groups are amine groups; the first compound is an epoxide compound comprising at least one vinyl group; the second compound comprises at least one vinyl group and at least one group comprising at least one phosphorus atom.

32. Process according to claim 17, which is a process capable of conferring or improving a given property of the polymer component.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0093] FIG. 1 is a .sup.1H NMR spectrum of a polyamide sample treated with glycidyl methacrylate according to Example 1.

[0094] FIG. 2 is a .sup.1H NMR spectrum of glycidyl methacrylate.

[0095] FIG. 3 is a .sup.1H NMR spectrum of an untreated polyamide sample as disclosed in Example 1.

[0096] FIG. 4 is a superposition of areas of the spectrum of FIG. 1 and FIG. 3.

[0097] FIG. 5 is an IR spectrum of a polyamide sample treated with glycidyl methacrylate (curve a) and of a polyamide sample treated with glycidyl methacrylate then diethyl allyl phosphate (curve b) according to Example 1.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Example 1

[0098] This example illustrates the implementation of a specific mode of the chemical modification process of the invention, which comprises, in a first time, a chemical modification of a polyamide-12 component with glycidyl methacrylate (named below GMA), this modification being carried out under supercritical CO.sub.2 in a specific reactor.

[0099] The simplified reaction diagram of this modification reaction may be the following:

##STR00002##

[0100] n, m and (n-m) corresponding to the numbers of repetition of repetitive units taken between square brackets.

[0101] The aforementioned specific reactor is a stainless steel reactor of the batch type of 600 mL equipped with an external heating system. CO.sub.2 is introduced into the reactor with a double piston pump the heads of which are cooled to a temperature less than 5° C. to have CO.sub.2 in liquid phase and avoid cavitation problems during the injection into the reactor. The reactor is preheated to a temperature above 31° C., in order to avoid the presence of liquid CO.sub.2 in the reactor. The reactor is equipped, in its bottom, with a crystalliser of 60 mL capacity intended to receive the functional compound, the catalyst and the cosolvent. The polyamide-12 component is suspended in the reactor above the reagent to avoid any contact with the crystalliser.

[0102] More specifically, the polyamide-12 component is a polyamide-12 tensile specimen of dimensions 61*9*3.7 mm for the widest portion of the specimen and 61*3*3.7 mm for the thinnest portion of the specimen.

[0103] In the crystalliser of the aforementioned reactor are deposited 10 mL of glycidyl methacrylate (referred to hereafter as GMA), 2 mL of triethylamine and 20 mL acetone. The aforementioned specimen is placed above the crystalliser and is not in contact with the liquids contained. The role of the acetone added in the crystalliser is to dilute the glycidyl methacrylate, in order to avoid its self-polymerisation during reaction and has not specifically been re-added to improve the penetration of the compound into the polyamide or the solubility of the glycidyl methacrylate in the supercritical CO.sub.2.

[0104] Once the reactor has been reclosed and sealed, CO.sub.2 is added via a pump in the reactor until 50 bar is reached at ambient temperature. The reactor is subsequently heated to 50° C. and the pressure is adjusted to 100 bar. The heating set point is subsequently set at 140° C. The reactor changes from 50° C. to 140° C. and from 100 bar to 300 bar in 1 h. After 6 hours of treatment at 140° C. and 300 bar, the reactor is depressurised from 300 to 70 bar in 10 minutes and from 70 bar to atmospheric pressure in 5 minutes, the depressurisation being performed via various valves placed on the cover of the reactor.

[0105] The reactor is subsequently opened and the specimen that has become brown is recovered then dried in the oven under vacuum at 105° C. overnight, its mass after drying being stable. The mass of the specimen has changed from 1.16 g before treatment to 1.23 g after treatment and drying. The gain of mass is therefore 6%.

[0106] The colouring caused by the modification by GMA is observed even at the core of the specimen treated in accordance with the process of the invention. It is also observed an intensity gradient of the colouring of the exterior at the core of the specimen as well as disparities within the actual component. These disparities correspond to stripes observed on the untreated specimen and caused by the method for manufacturing polymer components.

[0107] In order to ensure effective chemical modification of the specimen, this was characterised by .sup.1H NMR.

[0108] For this, 20 mg of polymer, taken in the thinnest portion of the specimen, are dissolved in a mixture 8:2 by volume of hexafluoroisopropanol and of deuterated chloroform. The .sup.1H NMR spectrum is acquired on a 400 Mhz Bruker Avance II spectrometer with 128 scans at 298 K for the polyamides thus dissolved, this spectrum being illustrated in FIG. 1. It should be noted that, during the dissolution of the treated polyamide sample, the extreme surface of the piece of the component was not dissolved by the solvent, and this probably due to a high level of chemical modification at the surface of components having significantly reduced the solubility of the polymer in the solvent.

[0109] By way of comparison, the GMA is analysed in pure CDCl.sub.3 with a concentration of 1% by volume and by using the same analysis parameters as in the case of the polyamides, the .sup.1H NMR spectrum being illustrated in FIG. 2.

[0110] By way of comparison, an untreated piece of specimen was analysed by using the same analysis parameters as in the case of the treated component, the .sup.1H NMR spectrum being illustrated in FIG. 3.

[0111] Zooms of a superposition of the spectrum of the treated component and of the untreated component are illustrated in FIG. 4.

[0112] On this superposition, it is observed 3 new peaks on the spectrum of the treated component: a peak at 1.98 ppm corresponding to the methyl group present on the GMA, a peak centred at 5.78 ppm and a peak at 6.23 ppm both corresponding to vinyl protons present on the GMA. The residue of the protons of the GMA is not observed on these spectra due to their probable superposition with the signals from the polyamide-12, much more intense, making their detection difficult. To quantitatively measure the grafting of the GMA in the polymer, the signals of the methyl group of the GMA and of methylene groups of the polyamide (peak at 2.28 ppm) are integrated and the global grafting degree (in %) is determined by the formula below:

[00001]$\mathrm{Global}\mathrm{grafting}\mathrm{degree}\left(\%\right)=\frac{2\times I_{\mathrm{CH}3\mathrm{GMA}}}{3\times I_{\mathrm{CH}2\mathrm{PA}12}}$

I.sub.CH3GMA being integral with the peak at 1.98 ppm corresponding to the methyl of the GMA and I.sub.CH2PA12 being integral with the peak at 2.28 ppm corresponding to a methylene group of the polyamide-12.

[0113] The calculation makes it possible to estimate the grafting degree at 3.8% molar. This measured grafting degree makes it possible to validate the grafting of GMA to polyamide-12 under supercritical CO.sub.2 in the conditions studied but does not make it possible to measure the modification gradient within specimens. It is furthermore probably underestimated due to the non-solubilisation of the surface of the specimen that is the portion the most likely to be modified.

[0114] This example makes it possible to show that a treatment under supercritical CO.sub.2 with glycidyl methacrylate makes modification at the core of polyamide-12 specimens possible.

[0115] The polyamide-12 component thus modified by GMA is, in a second time, modified again by making the vinyl groups of the residues of GMA react with a compound also including a vinyl group, in this case, diethyl allyl phosphate (DEAP), the simplified reaction diagram of this new modification that may be the following:

##STR00003##

[0116] m, (n-m) and p corresponding to the numbers of repetition of repetitive units taken between square brackets.

[0117] The treatment is carried out in the reactor such as defined for the first 5 step.

[0118] The following reagents are deposited in a crystalliser at the bottom of the reactor: [0119] 2.5 mL of DEAP; [0120] 0.2 g of azobisisobutyronitrile; [0121] 10 mL of acetone.

[0122] The PA-12 specimen is placed in such a way as to not be in contact with the liquids at the bottom of the reactor.

[0123] Once the reactor has been reclosed and sealed, CO.sub.2 is added via a pump in the reactor until 50 bar is reached at ambient temperature. The reactor is subsequently heated to 40° C. and the pressure is adjusted to 100 bar. After four hours of impregnation, the heating set point is set at 80° C. The reactor changes from 43° C. to 76° C. and from 100 bar to 270 bar in 1 hour (with pressure adjustment to reach the final pressure). After 3 hours of treatment at 80° C. and 2,700 bar, the reactor is depressurised from 2,700 to 70 bar in 10 minutes and from 70 bar to atmospheric pressure in 5 minutes.

[0124] The reactor is subsequently opened and the specimen is recovered then dried in the oven under vacuum at 105° C. overnight, its mass after drying being stable.

[0125] The specimen is subsequently infrared analysed in ATR mode. The spectra of the surface of the specimen before (curve a)) and after modification by DEAP (curve b)) are provided in FIG. 5 appended, the ordinate corresponding to the intensity I and the abscissa to the number of waves N (in cm.sup.−1).

[0126] On this spectrum, a significant reduction of peaks at 1,640 and 1,550 cm.sup.−1, corresponding to the C═O bonds of amides and to the C—N bonds of amides respectively is observed. Furthermore, an enlargement and an increase of the intensity of the peaks at 1,120 and 951 cm.sup.−1 is observed, corresponding to the presence of P═O and P—OC bonds. In infrared, it is difficult to distinguish the formation of a C—C bond (case of the present reaction) due to its omnipresence in most organic compounds. The presence of signals corresponding to the presence of phosphorus compound therefore indicates the presence of DEAP. As its boiling point is towards 45° C. and the specimen has been dried under vacuum at 105° C. overnight, the presence of non-grafted DEAP would have been eliminated. The modification of vibrations of amide bonds may for their part be due to the presence of the acid phosphate group, which, by modification of the H bonds formed between the amides of the polymer, could have impacted the vibrations of the surrounding bonds such as the C—N and the C═O of amides.

[0127] The analysis therefore confirms the possibility of grafting in two steps a functional compound, in this case an organophosphorus compound for its flame retardant properties, a priori not graftable, directly on PA-12 by supercritical CO.sub.2 route.