Improved Reusable Capture Complex

Abstract

The present invention is in the field of an improved reusable capture complex and a method of releasable capturing an additive present in a polymer material. The capture complex comprises a catalyst entity, a magnetic nanoparticle, and a bridging moiety solely between the catalyst entity and the magnetic nanoparticle The present use and method provide a high reduction of free additive of a polymer material.

Claims

1. Use of an improved reusable capture complex for releasable capturing an additive in a polymer material to be degraded, the capture complex not being dispersible in water and comprising a catalyst entity, a magnetic or non-magnetic nanoparticle, and a bridging moiety solely between the catalyst entity and the magnetic nanoparticle, wherein the catalyst entity and bridging moiety are attached by a chemical covalent bond and wherein the bridging moiety and nanoparticle are attached by a covalent bond, wherein the catalyst entity comprises an aromatic heterocyclic moiety carrying a positive charge, and a negatively charged moiety, wherein the negative charge is on a metal salt complex moiety having a two- or three-plus charged metal ion or a negatively charged counter-ion, wherein the nanoparticles have an average diameter of 2 nm-500 nm, and wherein the bridging moiety is present in an amount of 5*10.sup.−10-0.1 Mole bridging moiety/gr nanoparticle.

2. Use according to claim 1, wherein the bridging moiety comprises one or more of a weak organic acid, silyl comprising groups, and silanol.

3. Use according to claim 1, wherein the magnetic particles are at least one of ferromagnetic particles, anti-ferromagnetic particles, ferrimagnetic particles, synthetic magnetic particles, para-magnetic particles, superparamagnetic particles, wherein the magnetic particles preferably comprise iron oxide, or wherein the nanoparticles comprise a metal oxide.

4. Use according to claim 1, wherein the aromatic heterocycle moiety has at least one nitrogen atom to which a linking group of the bridging moiety is bonded.

5. Use according to claim 1, wherein the nanoparticle comprises at least one bridging moiety and catalyst entity.

6. Use according to claim 1, wherein the aromatic moiety is an aromatic heterocycle with at least one nitrogen atom, wherein the anion is an Fe3+ comprising salt complex moiety, wherein the nanoparticles are at least one of ferrite, magnetite, hematite, and maghemite, and wherein the nanoparticles have an average diameter from 3 nm-100 nm.

7. Use according to claim 1, wherein the polymer is one or more of a polyester, a polyamide, a polyamine, a polycondensate, and a polyether.

8. Method of capturing an additive releasable from a material, wherein the polymer is one or more of a pol-a polyamide, a polyamine, a polycondensate, and a polyether, comprising the steps of providing the additive, and capturing the additive under addition of an excess of the complex of claim 1.

9. Method according to claim 8, wherein the additive and complex are present in a hydrophilic solution, preferably an alkanol or alkanediol, and further comprising the steps of precipitating the complex and additive, removing the hydrophilic solution, adding a washing agent, dissolving the additive in the washing agent, and recovering the complex.

10. Method according to claim 9, wherein the washing agent comprises a hydrophobic solvent.

11. Method according to claim 8, wherein a polymer provides the additive upon degradation, and wherein the polymer is a mixture of waste polymers.

12. Method according to claim 11, wherein the polymer is a polyester.

13. Method according to claim 8, wherein the additive has an average size of 1-100 nm, and a molecular weight of 10-5000 Dalton.

14. Method according to claim 8, wherein the polymer is polyethylene terephthalate (PET) or polyethylene furanoate (PEF), the hydrophilic solvent is ethanediol, the catalyst comprises imidazolium, and FeCl.sub.4.sup.− or Cl.sup.− the bridging moiety is triethoxysilylpropyl or trihydroxysilylpropyl, and the nanoparticle is at least one of magnetite, hematite, and maghemite.

15. Method according to claim 8, wherein the capture complex is washed after 5-10 cycles.

16. Method according to claim 8, wherein the additive has an average size of 1-100 nm and a molecular weight of 10-5000 Dalton.

17. Method according to claim 8, wherein at least one additive is an organic pigment.

18. Method according to claim 8, wherein at least one additive is a metal-based pigment.

19. Method according to claim 18, wherein the additive is a TiO.sub.2 pigment.

20. Method according to claim 12, wherein the polyester is a waste material from polyester bottles.

Description

SUMMARY OF FIGURES

[0055] FIG. 1a-e shows chemical reactions and capture complexes.

DETAILED DESCRIPTION OF FIGURES

[0056] FIG. 1a shows chemical reactions. Therein poly(ethylene terephthalate) is degraded in 1,2-ethanediol. Similar results have been obtained with the capture complex of the present invention; in an example bim is used as aromatic catalyst entity. As a result Terephthalic Acid Bis(2-Hydroxyethyl) ester (BHET) is formed. Further, it is shown that BHET can be converted into dimers and oligomers (typically having 3-12 monomers).

[0057] FIG. 1b shows a schematic representation of the present capture complex. Therein A represents a nanoparticle, such as maghemite, B a bridging moiety directly attached to the nanoparticle, such as trisilanolpropyl, and C a catalyst entity, directly attached to the bridging moiety, with C1 being a positive catalyst moiety, such as bim, and C2 being a negative catalyst moiety, such as Cl.sup.−. If present (hence not shown) a tail would extent away from the nanoparticle.

[0058] FIG. 1c shows a nanoparticle A surrounded by a number of bridging moieties and catalyst entities and attached to the nanoparticle.

[0059] FIG. 1d shows an example of making one embodiment of the capture complex of the invention. In a first step 3-chloropropyltriethoxysilane is reacted over night with 1-butyl-imidazole under heating forming a BC sub-complex; herein the butyl forms a tail. A temperature is from 320-360° K, and depending on the temperature a reaction time is from 30-360 minutes. The reaction yields almost 100% BC sub-complex. The BC sub-complex is thereafter grafted on an iron oxide comprising nanoparticle. In this example, due to the presence of the carboxylic acid group, the grafted is understood to result in adhesion. Alternatively, in the presence of a silanol group, the grafting may be in the form of chemical bonding.

[0060] FIGS. 1d and 1e show reaction equations for formation of the capture complex of the invention in accordance with one preferred embodiment. In a first step (FIG. 1d) 3-chloropropyltriethoxysilane is reacted over night with 1-butyl-imidazole under heating forming a BC sub-complex; herein the butyl may be referred to as a tail. A temperature is from 320-470 K, and depending on the temperature a reaction time is from 30 min. to overnight. The reaction yields almost 100% BC sub-complex. The resulting intermediate is the combination of positively charged N-[3-(triethoxysilyl)propyl]-butylimidazolium and negatively charged chloride. Subsequently, a Lewis acid, such as FeCl.sub.3 may be added. However, that is not deemed necessary. In a second step, shown in FIG. 1e, the ethoxy-groups of the said reaction product thereof are converted to hydroxyl-groups, to result in a silanol-group. In a third step, that is for instance carried out in water or in ethanol or aqueous ethanol, the silanol is reacted with the nanoparticle surface, preferably in the presence of an acid. The resulting capture complex may thereafter be (re)dispersed in the desired solvent for the polymer degradation, for instance glycol.

EXAMPLES

[0061] Tests have been performed on coloured PET and previously for non-coloured PET. The results thereof are in the same order of magnitude for both conversion and selectivity towards BHET. As a consequence inventors conclude that a colour additive has hardly any or no impact in this respect. Even further, additives, such as pigments, can be removed from the degradation products, with ease.

[0062] Similar tests as above have been performed on a wide range of raw (PET) material, e.g. polyester clothing, PET carpet, PET material from automotive industry, recycled PET, multi-layered PET trays containing other polymers, such as PE and PP. The results thereof are in the same order of magnitude. As a consequence inventors conclude that the process is highly insensitive to different raw (PET) material and robust as well.

[0063] In an example inventors used 1 g of capture complex of FIG. 1e and 5 g of PET. Experiments showed that all colorants were removed by the complex, that is no colour was detectable in the obtained BHET/ethylene glycol (EG)/water phase.

[0064] It has been found that the present complex is capable of removing at least 2.5 mg colorant/g complex in one single use; examples show a removal of 25 mg colorant/g complex in a single run. When used in sequence of e.g. five times it has been found that the complex removes at least 12.5 mg colorant/g complex. When used for a large number of sequences (e.g. up to 50 times) there is been found no drawback in efficiency; hence the complex is considered to be capable of removing at least 125 mg/g complex. Such a capability is considered enough for most applications considered.

[0065] In one preferred embodiment, a washing step is per-formed in order to remove the captured compound. Advantageously, this washing needs only to be done after a series of runs or cycles If an amount of additive is large relative to the amount of capture complex the capture complex may be washed; typically the capacity for capturing additives by the complex, as indicated above is relatively large and the complex only needs to be washed after 5-10 cycles.

Further Examples

[0066] Examples Found of Degradable Polymers:

[0067] Polyesters: PET, PEF, PTT, PLA, polycarbonate

[0068] Polyethers: cellulosis

[0069] Polyamides: nylon 6

[0070] Ionic Liquids Tested:

[0071] An imidazolium based functional acid a piperidinium based functional acid, a pyridinium based functional acid, a pyrrolidinium based functional acid, a sulfonium based functional acid with an additional side group R3, an ammonium based functional acid with additional side groups R3 and R4, and a phosphonium based functional acid with additional side groups R3 and R4; all with at least side groups R1 and R2 and counter ion X—. X may be selected from F, Cl, Br, I, dicyanamide, bis(trifluoromethylsulphonyl)imide, preferably Cl.

[0072] The functional group R1 may be a (mono or multi, 1-4) carboxylic acid, whereas functional group R2 may be an alkane, typically a straight or branched alkane. Functional groups R3 and R4 may be selected from H, CH.sub.3 and R1 and R2. Functional groups R1-R4 have been selected independently and may be (partly) the same, or not. The side group R2 may have m or o carbon atoms may be branched, whereas the side group R1 having n (typically 4-20) carbon atoms is preferably unbranched.

[0073] So in summary aromatic and non-aromatic moieties had and have been tested, typically comprising a heteroatom (N, S, P), having a positive charge on the (or one of) hetero atom(s), and various side groups have been tested. The most promising have been claimed, namely the aromatic ones with a nitrogen atom.

[0074] Metal Salts:

[0075] Various metal salt comprising two- or three-plus charged metal ion and negatively charged counter-ions have been tested, especially Fe, Ca, Co, Mn, and the above counter ions.

[0076] Bridging Moiety:

[0077] For the bridging moiety weak and functionalize acids have been tested, such as a carboxylic acids and an oxysilane, such as methoxysilane or ethoxysilane.

[0078] Nanoparticles:

[0079] Various nanoparticles have been tested such as having O as counter ion, and Fe, Co and Mn as metal ion, and some combinations thereof. These function fine.

[0080] A size is typically relatively small, hence nanoparticles, with a lower value of 2 nm, and an upper value of 500 nm. Both have certain minor advantages and disadvantages.

[0081] Recovering Catalyst:

[0082] Most or all of the catalyst can be recovered easily, depending on the method of recovery. After 30 times recovery the amount recovered using magnetic recovery is higher than 98% of the initial amount, so virtually no losses. If filtration is used even higher amounts can be recovered.

Example 2: Depolymerisation Method

[0083] The reference scale of a laboratory experiment is 50 g of ethylene glycol (EG) in a 100 mL flask. The reference mass ratio of the reaction is 1 g of dry catalyst complex particles: 5 g of PET: 50 g of EG. The reference capture complex comprises 5 nm magnetite nanoparticles, trisilanolpropyl as bridging moiety and as ionic liquid (bim)FeCl.sub.4 or (bmim)FeCl.sub.4). A reference reaction was executed as follows:

[0084] The catalyst complex dispersion was homogenised by shaking for 5 minutes by hand. To 10 g of capture complex dispersion 41 g of EG was added and the liquids were shortly mixed by hand to homogenise the dispersion. Then, 5 g of PET flakes were added and the round bottom flask was placed in the heating set up. The PET flakes were prepared from colored PET bottles commercially available from SPA®, as SPA® Reine (Blue in blue colored PET bottles) and SPA® Sparkling (Red in red colored PET bottles). The heating was started and after 20 minutes, the reaction mixture had reached the reaction temperature of 150-200° C. The reaction was followed in time by taking in-process-control samples to measure the concentration of BHET produced as a function of time. The concentration of BHET was determined with HPLC. The results are listed in Table 1. It was found that the reaction conditions (temperature, concentration of capture complex, type and size of nanoparticle) could be varied in sufficient broad ranges.

TABLE-US-00001 TABLE 1 Conversion of PET to BHET as a function of time for a reference PET depolymerisation reaction Time PET to BHET conversion [min] [%] 5 1.7 10 5.4 15 10.0 20 10.5 35 31.8 45 51.5 60 92.4

Example 3

[0085] After the depolymerisation reaction, water was added in a 1:1 ratio and the capture complex was separated from the liquid stream containing the monomer by magnetic separation. The liquid phase was decanted, leaving the capture complex as a slurry-like layer on the bottom of the beaker. The capture complex could be easily redispersed with ethylene glycol. To release the colorants from the capture complex, an organic solvent, in this example CH2Cl2 was added and stirred vigorously. The capture complex was magnetically sedimented leaving a clear red or blue supernatant, dependent on the type of bottle used for the flakes. The supernatant could be decanted and the capture complex could be redispersed in ethylene glycol again.

Example 4

[0086] Examples 2 and 3 were repeated using a white PET bottles, that contained white-colored pigment, apparently TiO.sub.2. However, when the magnetic sedimentation was performed in the presence of the organic solvent to release the pigment, the liquid phase was left with the sedimented capture complex. This was left to stand overnight and a white layer of pigment particles had sedimented overnight on top of the capture complex sediment.

Example 5: Preparation of a Catalyst Capture Complex

Preparation of the Linker-Catalyst Complex (Bridge-Catalyst)

[0087] An alkyl imidazole is mixed with a halogensilane in a 1:1 molar ratio and stirred at a slightly elevated temperatures for 8 hours.

Preparation of the Catalyst Complex

[0088] The nanoparticles are prepared based on the method first described by Massart et al. in 1981:

[0089] An Fe(II) solution is mixed with a Fe(III) solution in a 1:2 molar ratio respectively. The iron oxide nanoparticles are formed by a co-precipitation reaction in basic medium while stirring. Subsequently, the resulting iron oxide particles are washed water and ethanol.

[0090] Next, an adequate amount of linker-catalyst complex diluted with ethanol is mixed well with the dispersion of iron oxide particles, after which ammonia added. The reaction mixture is stirred for 15 hours. Depending on a ratio between linker-catalyst and nanoparticle an amount of linker-catalyst per nanoparticle may vary.

[0091] The particles are washed with acetone prior to redispersion in ethylene glycol.

[0092] The invention although described in detailed explanatory context may be best understood in conjunction with the accompanying examples and figures.

It should be appreciated that for commercial application it may be preferable to use at least one variations of the present system, which would similar be to the ones disclosed in the present application and are within the spirit of the invention.