CN100415708C - Depolymerization method and device - Google Patents

Abstract

The invention concerns the recovery of monomeric esters of substituted or unsubstituted acrylic acid or of monomers containing styrene from polymer material (66) containing corresponding structural units. According to the invention, the polymer material is brought into contact with a heat transfer medium inside a heated reactor (51). The heat transfer medium and the polymer material (66) are agitated inside the reactor (51), and gas, which forms inside the reactor (51) and which contains the monomer, is drawn out of the reactor (51). The heat transfer medium contains a multitude of spherical particles (67), which has been proven to be particularly advantageous for achieving high yields and purity of the monomer to be recovered.

Description

Depolymerization method and device

The present invention relates to a kind of from contain the unitary polymer materials of corresponding construction, reclaim the replacement or the method and apparatus of monomeric ester, vinylbenzene and/or the monomer styrene derivative of substitutional crylic acid not.

Acrylic ester polymer wherein has the acrylic glass of mainly being made by polymethylmethacrylate (PMMA), is used in particular for producing durable consumer goods.Often use moulding technology for this reason, in its process, produce polymer waste.For this reason, and for the used polymkeric substance waste product of recycling, processing is significant.Analogue also is applicable to polystyrene and contains cinnamic multipolymer and their processing.Acrylic ester polymer, particularly PMMA, polystyrene and contain cinnamic multipolymer and can be advantageously under certain temperature and pressure, decompose fully once more and obtain corresponding monomer.

Described a kind of method of carrying out continuously of PMMA depolymerization in the specification sheets foreword of DE 19843112A1, wherein plastics have been added in the hot extruder that two tight intermeshing screws rotations with automatic cleaning action are wherein arranged with pulverised form.Because heat and mechanical shearing effect in the forcing machine make the PMMA depolymerization.Formed methyl methacrylate (MMA) is extracted out and condensation through the exhaust dome in gas phase.In this method in the condensation product content of MMA between 89% to 97%, change, and the yield of MMA is less than 97%.In this method in the forcing machine heating of PMMA undertaken by jacket wall.But when reactor volume increased, sheath area (and so heatable wall area) diminished with the ratio of the reactor volume that will heat.For plant-scale main equipment, therefore need very high wall temperature, perhaps have to expect the reduction of yield.High wall temperature may cause local superheating, and this may cause forming the undesirable by product of infringement monomer purity again.

Equally PMMA can the depolymerization by fluidized bed pyrolysis as can be known from the specification sheets foreword of DE 19843112A1 in addition.Used eddy current material is that granularity is 0.3 to 0.7mm quartz sand.But need the equipment of complicated flow technique to flow to keep fluidized-bed.

DE 19843112A1 suggestion makes polymer materials contact with the mechanical whirlpool fluidizing solid (heating agent) of heat in reactor, derives and be condensate in this gained steam.In this method, hot heating agent is in reactor one end continuously feeding, and the refrigerative heating agent is discharged at the other end.Recommending size of particles as heating agent is 0.1 to 5 millimeter fine inorganic particles solid, or based on silicon, aluminium, magnesium, zirconium or by the oxide compound of the natural existence or the synthetic preparation of these elementary composition mixtures.

Therefore in aforesaid method, need heating installation independent, that separate with reactor and the equipment that heating agent is introduced reactor and heating agent discharged reactor.Heating agent is discharged the process of reactor and also must and therefore coordinate mutually, to obtain required monomer yield with the residence time of polymer materials with the kinetics of depolymerization.

The purpose of this invention is to provide a kind of method and apparatus that from contain the unitary polymer materials of corresponding construction, reclaims replacement or unsubstituted acrylic acid monomeric ester, vinylbenzene and/or monomer styrene derivative, it can be realized with the net heat transmission of low Technology cost acquisition to polymer materials, and obtain uniform temperature distribution basically at least in the subregion of space reactor.

In the inventive method, polymer materials contacts with heating agent in the reactor of heating, and heating agent and polymer materials move in reactor, contain the monomeric gas that produces and drawn reactor in reactor.Shown that astoundingly if heating agent contains a large amount of spherical particles, then even without the fluidization of complexity, depolymerization method also produces good result.

But therefore proposing provides so a large amount of spherical particle with the production monomer gas under the situation of apparatus of the present invention in reactor heating.At this, have a kind of mobile equipment, with move in reactor contain spherical particle and polymer materials will mobile material (Bewegungsgut).

Spherical particle may be to compare with the particle of other shape to the reason of the wonderful effect of depolymerization, spheroid relative to each other between, with respect to reactor surface and the surface of any possible equipment of wherein arranging (as heating system and/or mobile equipment) and with respect to polymer materials can especially easily slide and therefore spheroid mix particularly well each other and with the each several part of polymer materials.Therefore can realize from the net heat transmission of heating system on polymer materials, and realize in the subregion of space reactor that at least uniform temperature distributes basically.

As for sphere size, in experiment, proved 0.075 to 0.25mm, preferred 0.1 to 0.2mm diameter is favourable.In this size range, single spheroid still keeps sizable thermal capacity for depolymerization, the fluid particles of can especially easily sliding on the other hand-be similar on the one hand.

Mobile equipment can have design not of the same race.Particularly can use any version well known to those skilled in the art, as moving or the wall of rotation or other moving-member of reactor.For instance, mobile equipment can also have parts or a plurality of parts of carrying out mechanical vibration and/or continuing linear (or even curve) motion, and in this generation and/or keep will the motion of mobile material in reactor.The mobile equipment that preferably has one or more rotating shafts, this has hybrid element and/or other hybrid element of oar sigmoid especially.Axle can for example stretch along level or vertical direction.For example, the mixing equipment that has the axle that vertically stretches in reactor vessel is favourable for the good mixing result, has fixed at least one along the radially-protruding hybrid element of axle on this axle.This embodiment allow to small part will mobile material movement continuously, at this because particle is spherical, the hybrid motion that mobile material inside continues.

Spherical particle is preferably stayed in the reactor during depolymerization, rather than described at reactor one end feeding as DE 19843112A1, discharges in the opposite end.Stay by spherical particle and greatly to have simplified this method in the reactor.Also can avoid in the case describing among the DE 19843112A1 in the reactor outside to the relative complex of heating agent and be full of the heating (to this referring to following paragraph) of loss.Therefore, preferred spherical particle moves and is retained in the reactor by the hybrid element of continuous drive.But the invention is not restricted to spherical particle is retained in the reactor.Other embodiment of the present invention also can realize simply than the better thorough mixing of the conventional heating agent of use, or pass through the more thorough mixing of simple method realization par.Particularly low energy, the corresponding smaller power mobile equipment and just enough of driving than low heating power.Avoided having the local superheating of above-mentioned disadvantageous effect.

In a preferred embodiment, with the reactor or the parts direct heating of reactor at least, preferred electrically heated.For instance, the zone of the inside sensing reactor inner space of reactor heating outer wall, and/or heating is arranged at least a portion of the mobile equipment in the reactor.Particularly at least a portion of reactor or inside reactor is connected to heating installation in heat conducting mode, and wherein said part repeatedly contacts with each particle in the move operation process of spherical particle.Under helping, realized particulate good transfer of heat like this to polymer materials.

If polymer materials contains the acrylic acid series compound, then heating agent particulate medial temperature is in particular 250 to 600 degrees centigrade in the reactor, preferably is lower than 425 ℃, the spontaneous ignition temperature of MMA under the situation that reclaims MMA.Even hereinafter also the experiment of explanation shows that method of the present invention can realize that also monomeric high yield also has its high purity equally under the low temperature like this.

In an embodiment of the inventive method, polymer materials is heated and depolymerization during its residence time in same reactor vessel.Do not require herein-as for example from known the DE3146194A1-preheating polymer materials in the heating space of real space reactor upstream, because owing to spherical particle takes place from thermal source heat passage especially fast on polymer materials, also because can realize the temperature distribution of special homogeneous.

But the present invention is not limited to this step heating means.Or rather, for example preheating in belonging to the charging tank of reactor of polymer materials, or introduced in this type of charging tank after the preheating.

Spherical particle preferably is made up of the material that non-reactively participates in MONOMER RECOVERY.Can simplify thus or even exempt processing heating agent.For instance, the very suitable material of steel as spherical particle.Preferred especially stainless steel particularly contains chromium and contains nickel steel, as 18/10Cr/Ni steel (V2A steel) or 17/12/2Cr/Ni/Mo steel (V4A steel).Even Standard Steel has just had excellent elasticity, make-under the suitable mechanical stimulus that gives by mobile equipment-and reach easy sliding, yet reach the jump sample motion of individual particle, this has quickened hot distribution.In addition, stainless steel is suitable to particularly well material, because it has resistivity to the chemical reaction of the multiple material in the polymer materials in introducing reactor or with the chemical reaction of this polymer materials.In addition can low cost production by the spheroid that V2A steel or V4A steel are formed.

Depolymerization is preferably in shielding gas atmosphere, as carrying out in nitrogen atmosphere.At this, the pressure in the reactor can be to be lower than, or is equal to or higher than environmental stress (identical with the normal atmosphere of earth atmosphere usually).Be higher than atmospheric pressure if use, then this is for example for being up to 133.3hPa (100 holder).Although the present invention also comprises the higher atmospheric pressure that is higher than, they mean higher technical device cost in practice.Be higher than atmospheric pressure and be preferably 50 to 80hPa (37.5 to 60 holders), particularly 65 to 70hPa (48.75 to 52.5 holders).If the use pressure below atmospheric pressure, for example this can be to be lower than environmental stress 80 to 133.3hPa (60 to 100 holder).Equally, this more high pressure (promptly more low absolute pressure) also be possible.

In a special embodiment of the present invention, provide gate equipment in reactor, to introduce polymer materials, wherein this gate equipment comprises a gate chamber.Have first closing device of arranging at the inlet side of gate chamber and second closing device of arranging at the outlet side of gate chamber in addition.Gate chamber combines with evacuating equipment and air charging apparatus, makes when first and second closing devices are closed, and gas can be full of with shielding gas from gate chamber extraction and gate chamber.Can repeatedly when first closing device is opened, introduce a certain amount of polymer materials in each case in this way and enter gate chamber; the gate chamber of finding time; shielding gas is imported gate chamber, then, after opening second closing device, polymer materials is introduced reactor.

Just be in the shielding gas atmosphere because be about to be introduced into reactor prepolymer material, so can not carry out directly reactor being full of shielding gas.Particularly, this allows reactor adiabatic better, in case thermosteresis.

The present invention is described on illustration ground in more detail on the basis of accompanying drawing below.But the invention is not restricted to these embodiment.Each figure signal face of land shows in the accompanying drawing:

Fig. 1 reclaims the equipment of monomeric substance from polymer materials,

Fig. 2 contains the reactor of the heating of monomeric gas by the polymer materials production among the last figure,

Arranging of the spherical particle that the mixed element of Fig. 3 moves,

Fig. 4 move a certain moment in later stage by the arranging of Fig. 3, and

Fig. 5 is installed in reactor upstream shown in Figure 1 in an embodiment and is used for making polymer materials enter the gate equipment of reactor by gate.

Equipment shown in Figure 1 is used for depolymerization and reclaim MMA in an embodiment.But, if it can-pressure and temperature-alternative in the reactor 1 of accommodation equipment is used to reclaim other replacement or the not monomeric ester of substitutional crylic acid, vinylbenzene and/or monomer styrene derivative.

Equipment hereinafter described is an embodiment just as already mentioned like that.The single or multiple integral parts of equipment can be substituted by other integral part.Particularly, the method for polymer materials being introduced reactor hereinafter described, the processing of the reactor self and/or the monomer gas of drawing from reactor can embodied in other.

The position for the treatment of the polymer materials of depolymerization is in charging tank 23, and its exit and measuring apparatus 21 connect together.Polymer materials enters gate chamber 19 through measuring apparatus 21.Also will explain the embodiment of gate equipment in more detail by Fig. 5.Gate equipment and gate chamber 19 are used for making polymer materials enter reactor 1 by gate, make the depolymerization operating process to carry out in shielding gas atmosphere.

Polymer materials is introduced reactor 1 through the stuffing hole 14 of reactor 1.Reactor 1 shown in Figure 1 is the reactor of axle 3 heating with continuous drive of along continuous straight runs orientation, and a lot of arms 11 are from axle 3 extending radially out along axle 3.Arm 11 come the right end of read fortune from axle 3, under each situation, all be furnished with a hybrid element 13, it has triangular shaped shown in the cross section in an embodiment.Hybrid element wherein also can comprise arm, also different designs can be arranged, and as oar shape, and/or the end of each arm connects upward a lot of hybrid elements.Depend on the type and the size of used spherical particle (heating agent) and/or depend on the type of part of polymer materials and size and select suitable hybrid element.For instance, polymer materials can be handled before introducing reactor by different way, particularly is ground into the segment and/or the shape of different size.A kind of commonly used and suitable method is most relatively polymer materials to be torn up (Schreddern) obtain being of a size of less several millimeter to more several centimetres segment.Because particle is a spheric,, under good yield and high purity, carry out so depolymerization method can use the polymer materials of different size and shape.

Fig. 2 shows the alternative design of reactor, and promptly reactor 51 has vertical orientated turning axle 53 and has the oar shape hybrid element 63 that a plurality of (three in this case) and axle 53 directly are connected and extend radially from axle 53.Represent that with linear straight line hybrid element 63 is but that diagram is understood.In embodiments can be vertically and/or horizontal direction realize the curvature of hybrid element 63.

Fig. 2 show need 63 that move by hybrid element, contain polymer materials segment 66 and spheroid 67 will mobile material 65 (clear in order to describe orderliness, only divide at reactor 51 mixed elements 63 three one of fan-shaped in demonstration).The shape of spheroid 67 can easily move relative to each other and move with respect to polymer materials segment 66 them.Therefore will mobile material 67 inside do not taking place mechanical interlocked or blocking.For guaranteeing good especially mobility to be arranged mobile material inside, preferably the cumulative volume of spheroid particularly is that its twice is big greater than still being the cumulative volume of solid polymer materials segment at least in reactor.This has been avoided the polymer materials segment to stick to each other or interlocking basically.

The adhesion of polymer materials because special under the situation of PMMA, does not take place in the spheroid that also preferred use is made by stainless steel on spheroid.But the high mobility of spheroid helps all in each case to prevent that polymer materials is on the hybrid element, on other parts of mobile equipment and/or adhesion on reactor wall.

As shown in Figure 2, reactor 51 has electric heating system 59 at least on sidewall of reactor.Sidewall of reactor and bottom surface are preferably heated on whole surface basically and/or are passed through along the equally distributed heating installation heating of wall.For instance, not only in this specific embodiment, can also use the heating installation of a conventional resistive heating system and/or an influential action.

With regard to reactor shown in Figure 11, the oversheath of reactor 1 is circular in an embodiment, heats by heating installation 9 on whole surface.For obtaining axle 3 good long term operating performancies, axle 3 can combine with axle cooling system 5.

Owing to hybrid motion with owing to the spheroid that is present in the reactor 1, polymer materials is heated and depolymerization at short notice in reactor 1.The PMMA segment is five to 60 seconds until changing into the general time that needs of monomer gas phase fully, depends on average spheroid temperature.

Gaseous state MMA derives and enters through monomer gas pipeline 25 tripping device 27 of separate addn wherein such as tinting pigment through the pore 15 of reactor 1.As shown in Figure 1, tripping device 27 cyclonic separator particularly.Additive can be drawn through vent line 28 by pump 29 from tripping device 27.Except that MMA and additive, shielding gas (herein being nitrogen) also enters tripping device 27.Shielding gas is derived dividually or with MMA with MMA subsequently.

MMA/ shielding gas mixture imports refrigerating unit 33 (as expander) through connection line 31; on the gaseous mixture that is sprayed onto heat still in the shower facilities, and this gaseous mixture was cooled in the very short time by nozzle for chilled in advance with the part therein and condensation product that refluxes.This can further improve monomer yield and purity.This has significantly reduced issuable solid deposits on other conventional water cooler.For refluxing, refrigerating unit 33 is derived pipeline 35 by monomer and is connected to monomer container 37, and the refrigerative monomer enters in this container 37 after deriving.The monomer that partly is arranged in monomer container 37 is returned to the nozzle of eminence device through reflux pipeline 40 by pump 41.A cooling apparatus 43 of operation is continuously arranged in the reflux pipeline 40.

Another pipeline 38 by being connected with monomer container 37 in the monomer slave unit is derived drivingly by pump 39.Additional backflow in refrigerating unit 33 may be undertaken by the connection line that is connected to pipeline 38, and described connection line can cut off by valve 47.For this purpose, the other end of connection line 46 streamwise that has been connected to reflux pipeline 40 is positioned on cooling apparatus 43 offsides that part of of continuous operation.The nozzle place of refrigerating unit 33 gets temperature and can control by the monomeric respective mixtures of the backflow of by-pass valve control 47 and differing temps.

Fig. 3 and Fig. 4 have illustrated the important result of heating agent particulate spherical form of the present invention once more.As shown downwards shown in the double-lined arrow of indication, be moved, and this motion is passed to two other spheroid 69,70 near it near the spheroid 68 of hybrid element 63.Spheroid 69,70 gained move through two arrows and illustrate.The result is that spheroid 69,70 is pushed open under the very little resistance of motion each other, allows spheroid 68 easily by (as shown in Figure 4).The corresponding sports of spheroid also may be to take place with respect to the polymer materials segment under same harmonic motion resistance.

Fig. 5 shows gate equipment 22, and it for example can be installed in the upstream of reactor 1 in the device of Fig. 1.Inject connecting leg 20, it for example is connected with the metering outfit 21 that shows among Fig. 1, leads to the gate chamber 19 of gate equipment 22.Inlet side at gate chamber 19 is furnished with first closing device, is in an embodiment to go up closing device, and it can be closed by the closing element 80 that can move around in the embodiment of described gate equipment 22 and inject connecting leg 20.The design of closing device 71 normally can be sealed gate chamber in the inlet side resistance to air loss.At the outlet side of gate chamber 19, in the case below gate chamber, one second closing device 72 is arranged, it can close the polymer feed pipeline 17 that leads to reactor by the closing element 81 that can move around in an embodiment equally.The design of second closing device 72 also is like this, and it can seal container 19 (being at outlet side in the case) resistance to air loss.

Also have a gas tube 74 that is combined with main valve 78 to be connected in addition with gate chamber 19.Main valve 78 from that right side of gate chamber 19 direction read fortune a T shape section 75 is arranged, from then on 74 of gas tubes turn to top set and inferior division.In top set, be furnished with pump 76.In inferior division, be furnished with shielding gas valve 79.Inferior division leads to for example at shielding gas feeding line 18 shown in Figure 1.Last inferior division needn't be led up and down respectively as shown in FIG., but any suitable direction that can lead.

In the depolymerization operating process, equipment particularly shown in Figure 1 or another equipment run duration repeat filling reactor with a certain amount of polymer materials.For this purpose, the polymer materials of this amount is at first filled gate chamber 19 by injecting connecting leg 20.Herein second, closing device 72 has been closed down.After polymer materials is introduced, first, go up closing device 71 and also close.Open main valve 78 (unless it is opened) then, and pass through pump 76 from gate chamber 19 withdrawing gass (particularly air).Shielding gas valve 79 has cut out herein.Turn off pump 76 then, and then cut off the top set of gas tube 74 if necessary in addition.Shielding gas also imports gate chamber 19 when opening main valve 78 and opening shielding gas valve 79 then, until reaching required pressure.The resulting pressure that reaches in the gate chamber 19 preferably is higher than the pressure of shielding gas in the reactor herein.This can compensate on the one hand by monomer/shielding gas mixture and derive the shielding gas loss from reactor that causes from reactor, secondly can prevent to enter by the polymer feed pipeline the spilling of monomer/shielding gas mixture of gate chamber 19.

In case after having reached resulting pressure in the gate chamber 19, open second, descend closing device 72, and thus a certain amount of polymer materials is introduced reactor.

The design of the depolymerization operating process in the reactor and the EXPERIMENTAL EXAMPLE of enforcement are hereinafter also described.

Embodiment 1: the oar formula reactor of selecting diameter 280mm, length 400mm.The steel ball of 12 kilograms of diameter 0.2mm is packed in this reactor as heating agent.In separating collecting process; the medial temperature of spheroid is 456 degrees centigrade; the atmospheric pressure that is higher than of shielding gas in the reactor (being nitrogen among the embodiment) is 66.7hPa (about 50 holders), and based on the pressure of earth atmosphere on the sea level, the revolution of oar formula reactor axle is 100rpm.Use as shown in Figure 1 device structure to obtain that the MMA yield is 97%, purity 98.5%.

Embodiment 2: as correspondingly carrying out among the embodiment 1, but 20 kilograms of steel balls are packed in the reactor, and the spheroid medial temperature is adjusted to 380 degrees centigrade.The MMA yield is 98%, and purity is 99%.

Embodiment 3: experimentize as described in embodiment 2, but the medial temperature of spheroid has only 320 degrees centigrade in the method.The MMA yield is 98.5%, and purity is 99%.

Claims (12)

1. one kind reclaim to replace from contain the unitary polymer materials of corresponding construction or the method for monomeric ester, vinylbenzene and/or the monomer styrene derivative of substitutional crylic acid not, wherein

-the heating reactor (1; Polymer materials is contacted with heating agent,

-with heating agent and polymer materials at reactor (1; 51) move in and

-will be at reactor (1; 51) the monomeric gas that contains that forms in is derived reactor (1; 51),

Wherein heating agent comprises the spherical particle that a large amount of diameters are 0.075mm-0.25mm (67).

2. according to the process of claim 1 wherein that polymer materials comprises the acrylic acid series compound, and wherein at reactor (1; 51) medial temperature of the particle (67) of heating agent is 250 to 600 degrees centigrade in.

3. according to the method for claim 1 or 2, wherein reactor (1; 51) be electrically heated.

4. according to the method for claim 1 or 2, wherein spherical particle (67) is made up of the material that unreacted ground participates in MONOMER RECOVERY.

5. according to the method for claim 4, wherein spherical particle (67) is made up of stainless steel.

6. according to the method for claim 5, wherein spherical particle (67) is formed by containing chromium and containing nickel steel.

7. according to the method for claim 1 or 2, wherein the diameter of spherical particle (67) is 0.1 to 0.2mm.

8. according to the method for claim 1 or 2, wherein spherical particle (67) moves and is retained in reactor (1 by the hybrid element of continuous drive; 51) in.

9. according to the method for claim 1 or 2, wherein polymer materials and spherical particle are moved in shielding gas atmosphere.

10. according to the method for claim 1 or 2, wherein just be introduced into reactor (1; 51) before, polymer materials is in the shielding gas atmosphere.

11. one kind from contain the unitary polymer materials of corresponding construction, reclaim to replace or not substitutional crylic acid monomeric ester or contain cinnamic monomeric device, wherein this device comprises following part:

-heatable reactor (1; 51), be used for containing monomeric gas from polymer materials production, and

-mobile equipment (3,11,13; 53,63), be used for the mobile reactor (1 that is present in; 51) in will mobile material (65), this mobile equipment with reactor (1; 51) part of combination or reactor,

Wherein will contain polymer materials and heating agent by mobile material (65), and wherein heating agent contains the spherical particle that a large amount of diameters are 0.075mm-0.25mm (67).

12., it is characterized in that having and be used for polymer materials is introduced reactor (1 according to the device of claim 11; 51) gate equipment (22); wherein gate equipment (22) comprises gate chamber (19); be arranged in first closing device (71) of the inlet side of gate chamber (19); be arranged in second closing device (72) of the outlet side of gate chamber (19); and evacuating equipment (74 wherein; 75; 76) and air charging apparatus (18; 74; 75,79) combine, make when first and second closing devices (71 with gate chamber (19); when 72) closing, can be packed into shielding gas from gate chamber (19) withdrawing gas and to gate chamber (19).

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