CN1092079A

CN1092079A - Desolvation method of elastomer solution

Info

Publication number: CN1092079A
Application number: CN 93101835
Authority: CN
Inventors: 施文峰
Original assignee: Chi Mei Corp
Current assignee: Chi Mei Corp
Priority date: 1993-03-08
Filing date: 1993-03-08
Publication date: 1994-09-14

Abstract

A process for removing solvent from a solution containing at least 8% by weight of an elastomeric polymer, which comprises mixing a warming fluid with a solution of the elastomeric polymer in a static mixing apparatus and rapidly heating the mixture, spraying the mixture into a vaporization chamber having an enlarged space, rapidly reducing the pressure to vaporize most of the warming fluid and solvent, evacuating the mixture by a vacuum system connected to a closely intermeshing twin screw feeder sealed at the outlet end of the vaporization chamber, forming the elastomeric polymer into a powder and feeding the powder to a main extruder by rotation of the closely intermeshing twin screw feeder, and removing residual solvent by injection of a degassing port in the main extruder and a degassing aid.

Description

The Desolventizing method of elastomer solution

The present invention relates to a kind of method that from elastomer polymer solution (elastomeric polymer solution), removes solvent; Clearer and more definite, the present invention relates to from containing the 8%(weight percent concentration at least) the solution of elastomer polymer, utilize and heat up rapidly and high efficiency vapor removal process (vapor removal process) and remove the method for its solvent.

In technology in the past, processing elastomer polymer solution obtains particulate state so that remove its solvent or block elastomeric mode roughly has two kinds, and just water vapor removes solvent method and direct desolventizing method.

It is to utilize high-pressure water vapor (pressurized steam) that water vapor removes solvent method, is injected in the solution that contains elastomer polymer, utilizes steam indirectly to water heating, and the heat of water is used for solvent flashing again.Solvent is removed the remaining moisture content in back, generally then need re-use water extracter removes, this is earlier most water conservancy to be extruded about 45%(weight with mechanical presses equipment) about moisture content, again with second de-aerator (for example single screw extrusion machine (single-screw extruder) or twin screw extruder (twin-screw extruder)) with residual moisture content except that to 1%(weight) below.The advantage of aforesaid method mainly is, utilize the heat of steam that the mode that polymers soln heats is belonged to indirect heating, than directly closing to its heating is slow, solution is difficult for producing the phenomenon of local superheating, therefore can prevent that elastomer polymer from (being gel, Gel) losing its due elasticity for insoluble composition being in crosslinked under the high temperature (crosslinking) for a long time.So for example polybutadiene rubber (butadiene rubber) or polyisoprene rubber elastomer polymers such as (isoprene rubber) just adopt the water vapor desolventizing to produce mostly.Yet water vapor desolventizing method has the shortcoming of a maximum, and promptly it invests in the appropriate litigation fees height of water removal device and drying plant, and a large amount of water needs aftertreatment, and its processing costs is not low yet, and therefore whole spent cost is very considerable.Moreover, the desolventizing mode that this is traditional, owing to use a large amount of water vapor and water, under the general running power of equipment used, its finished product of handling gained still contain residual moisture content to a certain degree.In known technology, general water removing machine can only be removed 90～95% moisture content, and 5～10% remaining moisture content must utilize its high calorie moisture content to be removed to again and only deposit 0.35% with huge dryer, just can reach general permission usage degree.As for the organic solvent (organic solvent) desiring to remove, in product, also still occupy certain ratio.This shows that the efficient of water vapor desolventizing method is very limited.As when requiring the moisture content residual quantity very low, then must improve the power of machine operation, so, certainly will consume the more energy.

The another kind of method that in the past was used to handle elastomer polymer solution is direct desolventizing method, it adopts without water vapor and directly utilizes heat that a kind of caoutchouc elasticity liquid solution is heated to 150～200 ℃, and then utilizes the mechanical means with degasifying effect to remove the process of solvent.For example, the Taiwan patent promptly is for the 184th, No. 257 to utilize 3～5 traditional vapor removal districts (vapor removal section) to remove solvent.What this patent was used removes solvent device 9 as shown in Figure 1, earlier with elastomer polymer solution direct heating to 150～200 ℃, be higher than under the solvent ebullient pressure one then, via loading hopper 90 it being sent into one has in the twin screw extruder 92 of suitable rotating speed, and make its generation decompression and make most of solvent gasification in charging place, utilize a traditional type degassing mouthful 80(vent port being positioned at loading hopper side after 90s again) at first remove 80～95%(weight) solvent, elastomer polymer solution then utilizes the propelling running of screw rod 94 and is heated between 180～250 ℃ once again and reach simultaneously.In loading hopper 90 the place aheads and be provided with 3～4 tradition degassings mouthfuls 81,82 and 83, its absolute pressure with polymers soln in screw rod working direction and gradually by barometric point reduce to about 5 millibars (mbar) or below so that remove remaining solvent.In addition, still several degassing auxiliary agent (for example water) inlets 96 can be set between each degassing mouth depending on the circumstances or the needs of the situation, promote removing of solvent so that inject the moisture content that accounts for polymer weight 0.5～2%.

Though foregoing invention can make volatile component (volatile compoment) content of last products therefrom reduce to 0.1%(weight), but it also is not suitable for heat sensitive elastomerics, this is because foregoing invention is to utilize the running of fuselage and screw rod and elastomer polymer solution is heated, when this elastomer polymer soltion viscosity (viscosity) in the desire processing was higher, its heating efficiency was extremely low.When for example utilizing this method to handle aforesaid polybutadiene rubber solution, if use the twin screw extruder (its structure is roughly identical with Fig. 1) of the ZSK-57 type of West Germany WP company, then, elastomer polymer solution make the heat transfer efficiency of itself relatively poor, so required time of the high temperature of desiring to make it be raised to 150～200 ℃ is just longer relatively owing to generally having higher viscosity.Under the situation of being heated for a long time, partial cross-linking reaction (cross linking) be very easy to take place and loses the elasticity of certain degree in polybutadiene elastomer, and this situation that follows the string has very big influence to elastomeric application.Usually as long as a spot of crosslinked promptly may causing when elastomerics is used for high impact modified polystyrene (high impact modification of polystyrene), form grit at product surface, the defective in this plastic shaping processing (plastic forming process) is commonly called as in Taiwan and is " flake ".If crosslinked generation is excessive, then except the surface can form in a large number " flake ", finally the elastomer modification effect also disappeared major part.

When the device 9 of aforementioned invention is used for the purifying (purify) of styrene-butadiene-styrene block copolymer (block copolymer); though do not have because of being subjected to heat cross-linking to lose the elastic problem of part; but owing to used degassing mouth 80,81,82 and 83 in this invention; for handling elastomer polymer; when the degassing, take a large amount of thin elastomer polymer powder out of easily and block degassing mouth; so must often shut down cleaning, cause the reduction of its service efficiency and practicality with the equipment of maintaining machinery.The major cause of thin elastomer polymer powder formation is that this will cause that elastomer polymer produces high speed foaming phenomenon owing in charging place and each degassing mouthful decompression that is taken place solvent is gasified fast; And when the elastomerics bubble destruction, can form fine powder.If the viscosity of solution is lower, elastomerics is healed foaming easily and is produced a large amount of fine powders, causes each degassing mouth seriously to get clogged.

United States Patent (USP) the 3rd, 917, a problem of once using for No. 507 a kind of double-screw type (twin interlockin gscrews) degassing mouth of tight engagement to avoid powder to block.People such as this double-screw type degassing mouthful similar Erdmenger are at German Patent the 915th, disclosed in No. 689, it is to utilize the screw thread twin screw of tight engagement each other, make therebetween slit only allow gas and liquid by removing, but solid powder/particle then can be blocked and squeeze back in the forcing machine by the screw thread of twin screw.Yet the feature of above-mentioned United States Patent (USP) mainly is to be separated out in the twin screw extruder stripping stage (stripping zone), and the downstream part in it injects a liquid, gas blended steam stripping agent (stripping agent) with high pressure, make it can be with respect to the plastic material solution for the treatment of desolventizing and adverse current (counter-current), carry volatile component and solvent simultaneously, again via the aforementioned double-screw type degassing mouthful discharge of being located at this stripping stage upstream end.This United States Patent (USP) is to adopt the mode at forcing machine peripheral hardware one heating interlayer to heat, but this mode palpus time of utilizing container outer wall to heat internal flow is longer, and only be applicable to volatilization component content low plastics, ABS plastic material (acrylonitrile-butadiene-styrene) for example, but then be not suitable for for elastomer solution or the too high material of organic solvent content.

By above narration as can be known, when elastomerics was extruded (extruded) in production, if superfine powder was no suitable design, then was easy to by the forcing machine mouth obstruction that flies out and will outgas.Moreover liquid heat transfer efficient is poorer because viscosity heals high, more needs high efficiency type of heating, and for example desire heating elastomer polymer content surpasses 6%(weight) solution just must use very large heat exchanger and high temperature just can reach; But because of for the overheated and crosslinked rotten elastomerics, this is again an adverse factors for easily.Therefore, in the desolventizing process of elastomer polymer solution, simultaneously avoid it to cross thermal metamorphism again if improve heating efficiency, and prevent that fine elastomer powder from blocking degassing mouth or with vacuum system (vacuumization system) obstruction, being still technical problem extremely to be solved at present when the degassing.

Main purpose of the present invention is to provide a kind of method that removes solvent from elastomer polymer solution, its utilization heats up rapidly and shortens the time that elastomer polymer solution is heated, avoiding it crosslinked rotten and lose original elasticity, and make the degassing mouthful avoid being subjected to the Hookean body powder to block by high efficiency degassing program again and need the inconvenience of pausing operation to clear up.

In order to achieve the above object, the invention is characterized in that the elastomer polymer solution feed is to the main extruder, this elastomerics is mixed in a static mixing device (static mixing unit) and makes it to be warming up to rapidly more than the volatilization point (volatilizing temperature) of solvent with fluid (for example water vapor) with heating, making it enter one again strengthens spatial vaporizing chamber (evaporizing chamber) and its pressure is die-offed, then at elastomer polymer solution and in heating with the fluidic mixture, most heating will be reduced and instant vaporization suddenly owing to pressure with fluid and volatile solvent, and elastomer polymer then forms finely powdered and separates with it.Degassing program then is to utilize the double-screw feeder that is connected with vacuum system this moment, with gas part oppositely being detached by this double-screw feeder pan feeding direction, can be at this with about 20～95%(weight of the pending contained whole solvents of elastomer polymer solution) extract, the elastomeric polymer that is finely powdered then is hampered by the tightly meshing twin screw in the rotation and is fed main extruder by its drive, utilize several degassing mouths on the main extruder to remove remaining solvent or other volatile matter again, extrude and obtain needed elastomer polymer through die head (die) then.

With regard to method of the present invention, elastomer polymer solution applicatory, wherein elastomer polymer content preferably is at least 8%(weight), preferred then is that elastomer polymer content is in 12%(weight) more than.The elastomer polymer of indication of the present invention is the homopolymer (homopolymer) that is selected from divinyl, isoprene, vinyl aromatic compounds (vinyl aromatic compound) and the multipolymer of conjugated diolefine (conjugated diene), and wherein conjugated diolefine can be the compound that part is hydrogenated (partially hydrogenated) or is not hydrogenated (unhydrogenated).Therefore, be applicable to that elastomer polymer of the present invention can comprise styrene butadiene and styrene-isoprene block copolymer or starlike (star-shaped) multipolymer, and vinyl-propylene-based block copolymer (vinyl monomer-propylene block copolymer), for example EPDM(ethylene-propylene-dienemonomer).

The method according to this invention, above-mentioned elastomer polymer solution need the program through heating up rapidly and reduce pressure and vaporizing and outgas earlier before being fed to main extruder.Heating up rapidly is under higher back pressure, elastomer polymer solution and one is heated heat up with fluid moment thorough mixing, and it can utilize a static mixer (static mixer) and finish.This heating mode tradition utilizes the speed of forcing machine fuselage or container outer wall heating internal liquid high.Utilize the characteristic of moment heated at high speed, can prevent that elastomer solution from producing partial cross-linking or high temperature deterioration, thermal destruction (thermal degradation) because of heat-up time is long; And owing to heat-up time is short, so the danger that also can avoid the well heater wall to be adhered to by full-bodied elastomer polymer solution.Heat and then can be water vapor or any solvent through heating in advance with fluid, as hexane (hexane), hexanaphthene (cyclohexane), pentane (pentane), iso-pentane (isopentane), benzene (benzene), toluene (methyl benzene), ethylbenzene (ethyl benzene), and acetone (acetone) etc., it is not limited to must be identical with the elastic polymer solution solvent for use.In addition, the Heating temperature of desiring to reach then can utilize water vapor or other suitably to heat fluidic consumption and pressure thereof and controlled, and generally uses the above pressure of 3bar can obtain good effect.

After the above-mentioned process that heats up rapidly, elastomer polymer solution under the high pressure is just sent forth to a vaporizing chamber than large space via shower nozzle with the fluidic mixed solution of heating, its pressure is reduced suddenly and make a large amount of heat fluid and volatile solvent moments become gas because of pressure reduces, then become finely powdered as for the polymkeric substance in the elastomer polymer solution, thereby form solid and gas isolating phenomenon in decompression process.In addition, the exit end of vaporizing chamber is to link the twin screw sealing that vacuum system is arranged so that carry out subsequently degassing program with one, it is with consolidating through decompression vaporization gained, liquid, gas mixture utilizes above-mentioned vacuum system that gas (the gaseous state thing of heat fluid and volatile solvent) is wherein extracted immediately, also extracted out by vacuum for fear of the elastomer polymer powder simultaneously with gas, the present invention adopts the twin screw feeding design of complete tight engagement (fullyinter-meshed), make the elastomer polymer powder owing to bleeding of vacuum system is sprayed onto on one's body the dual-screw-stem machine, and the screw rod in can being rotated again drive and the feeding main extruder.Process of this decompression vaporization and the degassing can make elastomer polymer solution before entering main extruder, is removed about 20～95%(weight) solvent (weight with the pending contained whole solvents of elastomer polymer solution is benchmark).

In main extruder, can along the forcing machine feed direction several be set as mode in the past and have the degassing mouth that the finely powdered elastomeric polymers can be pushed (extruding downward) downwards, to remove remaining heat fluid or solvent.Degassing mouth can be the aforesaid double-screw type degassing mouthful or the general degassing mouthful.In addition, also can between each degassing mouth, inject degassing auxiliary agent (enhancing agent) and remove when needed to promote the residual solvent or the fluidic of heating.The degassing auxiliary agent that is injected is lower boiling solvent, for example water, ethylbenzene, butane (butane), pentane, or hexane, and its consumption is preferably the 0.5-5%(weight of elastomer polymer weight).

Method of the present invention can be described in further detail in conjunction with following preferred embodiment with used device:

Brief description of drawings:

Fig. 1 is the 184th, No. 257 used Desolventizing apparatus of Taiwan patent.

Fig. 2 is the inner rough schematic of the used forcing machine drawing-in device of the inventive method.

Fig. 3 is the rough schematic of static mixing heating installation of the present invention inside.

Fig. 4 is the rough schematic of the another kind of static mixing heating installation of the present invention inside.

Fig. 5 is the elastomer polymer solution Desolventizing apparatus according to the inventive method design.

As previously mentioned, the method according to this invention, elastomer polymer solution is before the feeding main extruder, be to vaporize through quick heating and an instant decompression of heating fluid earlier, and utilize the double-screw feeder that is connected with vacuum system to carry out simultaneously the process that major part is heated removing of fluid and volatile solvent and the elastomeric polymer fine powder fed main extruder. Therefore, the present invention preferably uses drawing-in device 1 as shown in Figure 2. As shown in Figure 2, this drawing-in device 1 comprises a static mixing firing equipment 10, vaporizer 20 and a twin-screw drawing-in device 30 in regular turn.

The detailed structure of static mixing firing equipment 10 as shown in Figure 3, elastomer solution entrance 11 and at least more than one water vapour (or other suitable fluid of heating) entrance 12 is simultaneously and premixing cavity 13 connections. Steam entry 12 can freely be designed to multisection type, on it and be provided with check counterbalance valve 120. In premixing cavity 13, then can be designed to any parts of mixing of helping, for example in Fig. 3, premixing cavity 13 just is provided with a spiral helicine mixing assistor 130, in order to promote the even mixing of elastomer solution and water vapour, and improves its heating effect. In addition, also can be as shown in Figure 4, not additional any Computer Aided Design is subjected to force unbalance but cause, these water vapours in the premixing cavity 13 when high-pressure water vapor enters 12 of entrances can be designed to the relatively mode of configuration. Such as Fig. 3 or shown in Figure 4, static mixing firing equipment 10 still comprises a static mixer 14(static mixer), it is arranged at after the premixing cavity 13. The static mixing device 140 that static mixer 14 inner installings have mixed function, but this reference example such as former new I supervize " the basic application of silent oscillation blender " the 6th page (Nikkan Kogyo Shimbun) of showing, but be not limited to the cited content of this book (Fig. 3 or shown in Figure 4 only be an example). Static mixer 14 can make elastomer solution and water vapour (or other heat use fluid) reach moment to mix cmpletely effect with fast heating. Be provided with a distribution showerhead 15 in the exit of static mixer 14, it can make mixed liquor under the high pressure evenly send to the vaporizer 20 to reduce pressure vaporization and carry out subsequently degasification process forth.

As shown in Figure 2, the distribution showerhead 15 of above-mentioned static mixing firing equipment 10 extends into the front end of vaporizer 20. Vaporizer 20 is a bigger closed space, though its shape is without particular limitation, but diffused (divergent) or the arc preferably considering to prevent elastomer polymer to be attached to the possibility of vaporizer inwall and be designed to tilt, and can utilize and have the surperficial coating agent that prevents that elastomer polymer from adhering to, such as materials such as polytetrafluoroethylene (PTFE) (polytetrofluoroethylene), be coated on the inwall of vaporizer 20. The port of export of vaporizer 20 then utilizes a twin-screw feeding machine 30 to be sealed, and the elongated end in double-screw feeder 30 tops is provided with an opening 34, in order to link with the vacuum system (not shown). The axle center of double-screw feeder 30 can utilize the shaft seal element of big sealing gasket (Grand Packing) etc. or front mechanical seal to completely cut off motor 31 and vaporizer 2 0. In addition, as previously mentioned, in order to prevent when using vacuum system degassed, the pressed powder of elastomer polymer is drawn out of in company with gas, feeding machine 3 must adopt screw thread 33 fully closely to mesh each other the twin-screw 32 of (fully inter-meshed), make therebetween slot only allow gas and liquid by removing, but solid powder/particle then can be blocked and clamp-on to connect airtight in the main extruder 40 of the double-screw feeder port of export and (see Fig. 2 or Fig. 5) by the screw thread of twin-screw. The direction of rotation of twin-screw 32 can be in the same way or counter rotating again.

As previously mentioned, the port of export of twin-screw 32 is the feeding mouths that connect airtight in main extruder 40. The main machine 40 that squeezes can be single screw rod, twin-screw or multi-screw extruder, and the bolt rotary direction can be in the same way or counter rotating, and screw speed is preferably between 50～300rpm, more preferably between 150～250rpm. In addition, can as conventional art, be provided with firing equipment at main extruder, as shown in Figure 2, be embedded in the heating oil pipe 43 of fuselage or be coated on the electrothermal heating plate of fuselage. As shown in Figure 5, in main extruder 40, along the main extruder feed direction several are set and have degassed mouthful 401,402 and 403 of downward extruding design, in order to make once again still residual steam or the solvent that has solvent or other elastomer polymers that volatilizees compositions to remove remnants. Degassed mouth can be the double-screw type with the design of pressing down degassed mouthful of (as shown in Figure 5) or general degassed mouth (as shown in Figure 1), and its number is according to final products the requirement of residual solvent and water content to be decided. Appropriate location 42(between each is degassed mouthful is not limited to a place) then can be as aforementioned the lower boiling degassed auxiliary agent of injection to promote removing of residual solvent or steam. At last, treated final elastomer polymer then extruded by the die head (die head) 41 of main extruder 40 ends and .

As shown in Figures 2 and 3, when practical operation, elastomer solution can utilize pump (not shown) entrance 11 feeding premixing cavitys 13 through drawing-in device 1 under certain back pressure, and the fluid of heating then can use for example water vapour, makes it enter premixing cavity 13 via entrance 12. The purpose that premixing cavity 13 arranges is before elastomer solution and water vapour enter static mixer 14, and a cushion space that is pre-mixed is provided. Elastomer solution and water vapour just enter static mixer 14 after slightly doing in advance to mix in premixing cavity 13. In static mixer 14, the fluid of heating (water vapour) mixes with elastomer solution fully in moment on the one hand, one side also moment with its heat transferred elastomer solution in heat transfer rate solvent faster. Rule of thumb, this rate of warming is relevant with the pressure of the used fluid of heating. Heat fluid as example take water vapour, if its pressure more than 3bar, then can make elastomer solution be rapidly heated more than 60 ℃ in 3 seconds, just in the exit of static mixer 14, the temperature of mixed liquor is between 60～250 ℃. If the pressure of water vapour is lower than 3bar, then the mixeding liquid temperature in static mixer 14 exits will be lower than 60 ℃, and this can cause the solvent removal poor effect. As want to make the mixeding liquid temperature in static mixer 14 exits to be higher than 250 ℃, and then need use high steam, the method is not inconsistent economic benefit, can cause the phenomenon of rubber high temperature deterioration simultaneously yet. Utilize static mixer 14 and after reaching abundant mixing and quick heating, the mixed liquor of elastomer polymer solution and water vapour just leaves static mixer 14 and is sprayed onto vaporizer 20 through distribution showerhead 15.

fully mix through static mixing firing equipment 10 heat to solvent evaporates point with moment after, the elastomer polymer solution under the high pressure and The mixed liquor of water vapour just sprays into the space by distribution showerhead 15 and becomes suddenly big vaporizer 20, and the water vapour that this moment is a large amount of and volatile solvent are owing to pressure drop gasifies in mixed liquor. The relatively poor elastomer polymer of conductivity of heat is not heated to the high temperature same with solvent phase in static mixer 14, and therefore, in vaporizer 20, elastomer polymer only experiences of short duration high temperature, and gasification namely begins. When solvent gasified because of decompression at vaporizer 20, moment was taken away a large amount of heats with the heat of evaporation form again, heat up slow elastomer polymer so instantaneous temperature reduction, and the foaming phenomenon of high temperature takes place and form fine-powdered, and spray simultaneously with gas. So in this extremely short time, the polymer of heat-transfer capability difference does not bear the highest temperature, but solvent heats up equably and has vaporized. Therefore, elastomer polymer is in the process of heating, reduce pressure, gasifying, and on the one hand heated time is short, and the temperature of experience is gentle on the one hand, so can avoid because of long and the crosslinked rotten or deterioration at high temperature of heated time. Compare with traditional water vapour desolventizing method mentioned above, the present invention can reduce the consumption of heating steam, and does not need very big heating tank to carry out indirect. And come in the method for desolvation in traditional Steam Heating of utilizing, be evenly distributed in the heating tank for the ease of high steam, high efficiency mixer must be set, and in order to improve steam utilization, plural large-scale heating tank will be set mostly. But the present invention then can exempt the use of above-mentioned heating tank fully, and can avoid elastomer polymer solution by superheated.

When water vapour, volatile solvent and elastomer polymer after solid, gas takes place and separates in vaporizer 20, the vacuum system that the gas part is linked by double-screw feeder 30 immediately extracts from its top 34. In this stage, by the volatile solvent that extracted, account for the contained whole solvents of elastomer solution charging 20～95%(weight), if be lower than 20%(weight), then remaining solvent needs to remove from degassed mouthful of main extruder, this easily causes degassed mouthful to stop up, and the too high elastomer solution of solvent needs longer extruder to heat and degassed, and this will cause heat time heating time long and produce crosslinked or the high temperature deterioration. Then can be hampered by the screw thread 33 that twin-screw 32 fully closely meshes each other as for the elastomeric polymer that is fine-powdered, and be fed to main extruder 40 with its rotation. Utilize heating and the fusing effect of main extruder 40, again elastomer is melted, and make it through several degassed mouthful 401,402 and 403, or inject suitable degassed auxiliary agent if necessary in degassed auxiliary agent inlet 42 again, to slough remaining solvent or other volatile components; Through die head 41 elastomer polymer is extruded again at last and obtained final products.

Can describe the present invention by following examples and comparative example:

＜comparative example 1 〉

As shown in Figure 1, utilizing in the past, 9 pairs of elastomer contents of Desolventizing apparatus are 20%(weight) hexane solution carry out desolventizing and handle, measure each degassing mouthful in beginning to operate the back to the time of stopping up.Forcing machine 92 is for turning to complete tight engagement twin screw extruder ZSK-35 type (West Germany, West Germany, Werner ﹠amp together; Pfleiderer company makes).The length of this twin screw extruder is 120 centimetres (L/D=40), which is provided with four groups of degassing mouths 80,81,82 and 83.Elastomer solution is preheating to the spout that quantitatively pumps into forcing machine after 200 ℃ with toothed gear pump.

Used elastomerics has three kinds (a, b, c):

A is the styrene-butadiene-styrene block copolymer, and wherein styrene content accounts for 30% of segmented copolymer;

B is the styrene-butadiene-styrene block copolymer, and wherein styrene content accounts for 10% of segmented copolymer;

C is the homopolymer of divinyl, and commodity are called Asahi-Kasei 35AS, is low-cis-polybutadiene rubber (Low-Cis Butadiene Rubber).

The extrusion condition of three kinds of elastomer polymer solution is identical, and driving screw speed is 200rpm, and the pressure of degassing mouth 80,81,82 and 83 is set and is respectively 10mbar, 5mbar, 5mbar and 5mbar.Extruder temperature is 210 ℃, and only in degassing auxiliary agent inlet 96 injection water the removing with the help solvent of 82 and 83 in degassing mouth.

The degassing mouthfuls 80,81,82 and 83 is as shown in table 1 in the time that begins to be operated to obstruction, and its result shows the styrene content high elastomer solution of healing, and more is not easy degassing mouth is caused obstruction.The elastomerics that styrene content is higher, the feature after it melts, therefore are difficult for easily bubbling as blowing up a balloon so its visco-elasticity (viscoelasticity) is lower near plastics (plastic).Inspection degassing mouth 80 can find that tamper is the elastomer polymer of finely powdered, the degassing mouthful 81,82 and 83 then less discovery fine powders, and this is the amount of gas evolved maximum because of degassing mouth 80, so the fine powder that produces is also maximum.The generation of above once mentioning fine powder is owing to the gasification of solvent fast causes the fierce blistered result of elastomerics, if vacuum outgas is not used in the degassing mouthfuls 80, then can overflow along the degassing mouthfuls 80 except the bubble that produced, thereby take out of a large amount of

＜table 1〉three kinds of different elastomer solution a, b, c are to the influence of the degassing mouthful duration of congestion

Elastomer solution	80 ^＊	81	82	83
					a(30% ^＊＊）	25min	4hr	Do not block	Do not block
b(10%)	25min	1?hr	1?hr	20?min
					c(0%)	3min	10?min	14min	10min

*: degassing mouth

*: the shared weight percent of the vinylbenzene in the elastomerics

Elastomerics outside, similar phenomenon also can take place in the degassing mouthfuls 81,82, remaining quantity of this expression foaming phenomenon and solvent has direct relation.If the degassing mouthful 80 use vacuum systems, though then the degassing mouthful 81,82 and 83 fine powder generating capacities are less, and be not easy blocked, if but change the degassing auxiliary agent of inlet 96 into the hexane identical by water with the elastomer solution solvent for use, and when testing with elastomer solution a recast, result that then can table 2, its result shows, if used degassing auxiliary agent is for can dissolve elastomeric solvent the time, then the elastomer polymer of finely powdered can appear at the degassing mouthfuls 83.

＜table 2〉the different influences of auxiliary agents that outgas to the degassing mouthful blockage

Elastomer solution

Degassing auxiliary agent

80 ^＊

81

82

83

a

Water

25min

4?hr

Do not block

Hexane

25min

1?hr

20?min

*: degassing mouth

By above result as can be known, the method that No. the 184th, 257, the Taiwan patent can only be used for the elastomerics of styrene content height (being that physical properties is inclined to plastics) limitedly, but not general elastomerics.Moreover, because the general selected during fabrication solvent of elastomerics is the high volatile volatile solvent, for example to be to use boiling point be 69 ℃ hexane or 80.7 ℃ hexanaphthene to polybutadiene elastomer, therefore be heated to 150～200 ℃ and pump into the feeding mouth of forcing machine after, very fierce volatilization and foaming phenomenon take place immediately, this will cause the obstruction of vacuum system, so this currently known methods has very big difficulty when large-scale commercial production.

＜comparative example 2 〉

Use Desolventizing apparatus and the operational condition identical with comparative example 1, processing d, e, three kinds of elastomer contents of f are 20%(weight) hexane solution, wherein elastomerics d is the Asadene 35AS of Asahi Chemical Industry; Elastomerics e is the Asadene 55AS of Asahi Chemical Industry, and both are all and use organolithium catalyzer (organo-lithium catalyst) to synthesize the low-cis-polybutadiene rubber of (synthesis); Elastomerics f is special Zieglar Natta catalyzer synthetic cis-rich polybutadiene rubber (high cis butadiene rubber, synthetic rubber company in Taiwan produces, trade(brand)name Taipol 015H) for utilizing ferro-cobalt.Measure the time that each degassing mouthful is experienced to blocking after beginning to operate, and will analyze with " visible gel (Gel) assay method ", and the elastomer solution before handling with desolventizing compares through three kinds of elastomer product that desolventizing is handled gained.

" visible gel determination method " generally is to be used for defining elastomerics to include what of insoluble gel content, and its analytical procedure is as follows:

(1) elastomer sample is cut into the cubes of 1～2mm.

(2) accurately claim 5 grams.

(3) in the vial that is equipped with the magnetite stirrer, put into 250 milliliters of toluene, and place on the agitator and stir.

(4) the 5 gram rubber samples that weigh up in (2) are cut into pieces with scissors and drop in (3), stir and it was dissolved fully in 45～60 minutes.

(5) treat to dissolve fully after, utilize the Aspirator(vent fan) bleed, filter simultaneously with Buchner funnel and standard test filter paper.

(6) will spoon Du Pont (Dupont) brown oil (Brown Oil) of staining fluid (staining fluid is the 0.1%(weight that is dissolved in the toluene) after the filter paper taking-up in the above, it has dyeing to gel).

(7) before filter paper becomes dry, compare, decide the gel number with standard model.

(8) each sample is all tested averaged three times.

(9) judge the gel area,, then must add re-computation if area is excessive.

Elastomerics d, e, f are the elastomerics that is usually used in the impact-resistant polystyrene modification and makes purposes such as tire, yet be easily to be cross-linked under the high temperature can't the dissolved gel for its disadvantage.If in the desolventizing process, cause the inner gel content of elastomerics too high, when then it is used for the polymerization (polymerization) of polystyrene, easily form the defective of aforementioned being commonly called as " flake " at polystyrene surface.This comparative example is analyzed outside the elastomerics of desolventizing gained divided by " visible gel determination method ", is that 6% ratio is dissolved in and carries out polymerization in the vinylbenzene with it with weight ratio also simultaneously; Polymerization gained finished product connects plate squeezing machine (sheet extruder) with the ZSK-35 twin screw extruder, be extruded into the thin plate of 2mm thickness, in order to observing " flake " of thin sheet surface, and and use elastomer solution before desolventizing is handled with same 6%(weight) the ratio p-poly-phenyl ethene result that carries out modification do one relatively.

Table 3 is the synthesis result of aforementioned various analysis and test, its result shows the high elastomer solution of heat sensitivity after using known Desolventizing apparatus shown in Figure 1 to handle, the elastomeric inner gel content of gained heightens, and when using it for the modification to the anti-impact polystyrene, the gained finished surface a large amount of " flake " also can occur and influence its performance.Therefore, even use the Desolventizing apparatus of Fig. 1 to handle the more sensitive elastomerics of heat reluctantly, its inevitable defective on performance still can be destroyed the use value of finished product.

＜table 3〉synthesis result of three kinds of elastomer solution d, e, f various analyses and test before and after desolventizing

* 1: before desolventizing is handled

* 2: after desolventizing is handled

＜embodiment 1 〉

Utilize the device (see figure 5) of the inventive method to handle three kinds of elastomer solution a, b, c in the comparative example 1, wherein main extruder 40 still be ZSK-35, and the degassing mouthfuls 401,402 and 403 is all adopted has the twin screw that downward extruding designs.The degassing mouthful 401 pressure are set at 8mbar, and the pressure of the degassing mouthfuls 402 and the degassing mouthfuls 403 is 5mbar, and establish a degassing auxiliary agent inlet 42 the degassing mouthfuls 402 and the degassing mouthfuls 403, and to make water be degassing auxiliary agent, and it adds speed is 1.25kg/hr.The screw speed of main extruder 40 is 180rpm, and the pan feeding flow of the elastomer solution inlet 11 of drawing-in device 1 is 125kg/hr, and the fluid of heating uses water vapor, and its pressure and flow then are respectively 7bar and 50kg/hr.The temperature out of static mixer 14 records between 120～130 ℃.Double-screw feeder 30(Fig. 2), the tachometry of its screw rod 32 is that 150rpm(is with turning to).The extrusion capacity of main extruder 40 is about 25kg/hr.In addition,, except that being connected with vacuum system, a subcooling condenser is housed also, so that be collected in this solvent that is drawn out of and heat steam in the gas outlet end 34 of double-screw feeder 30.The vacuum tightness of vacuum system then is located at 12mbar.

As comparative example 1, measure each degassing mouth in beginning to operate the back to stopping up the time of being experienced, the result is as shown in table 4.

As shown in Table 4, utilize device of the present invention, no matter handle which kind of elastomer solution, each degassing is mouthful after through 200 hours operating time, phenomenon of blocking does not appear yet, therefore the styrene content in handled elastomer solution viscosity or the elastomerics still can be operated smoothly even without being restricted, and the situation that fine powder disperses no longer takes place.

In addition, with elastomer solution a is example, it can record hexane that 72kg is per hour arranged by the condenser that is installed in double-screw feeder 30 top exit ends 34 and the water of 45kg is drawn out of, account for the 72%(weight of hexane content in the former pan feeding), and, the elastomerics a that extrudes gained by main crowded machine 40 is taken a sample, with gas chromatography (gas chromatograph, GC) analysis learns that residual hexane is 520ppm, and moisture content is 3510ppm, and the desolventizing effect of visible the inventive method is fairly obvious.

＜table 4〉three kinds of different elastomer solution a, b, c are to using the influence of apparatus of the present invention degassing mouthful duration of congestion

Elastomer solution

	34 ^＊1	401 ^＊2	402	403
					a(30% ^＊3）	＞200hr	＞200hr	＞200hr	＞200hr
b(10%)	＞200hr	＞200hr	＞200hr	＞200hr
					c(0%)	＞200hr	＞200hr	＞200hr	＞200hr

* 1: the top exit end 34(that double-screw feeder 30 is connected with vacuum system sees Fig. 2)

* 2: the degassing mouthful

* 3: the shared weight percent of the vinylbenzene in the elastomerics

＜embodiment 2 〉

Used Desolventizing apparatus, pending elastomer solution kind, and operational condition is all identical with embodiment 1, but the elastomer content among three kinds of elastomer solution a, b, the c reduces to 15%.Each degassing mouth of result is as shown in table 5 to blocking the time of being experienced from the operation beginning.

The result of table 5 shows that even pending elastomer solution, its solvent is higher, and the Desolventizing apparatus of use the inventive method still can not cause the phenomenon of fine powder obstruction at each degassing mouth.

＜table 5〉three kinds of different elastomer solution a, b, c are to using the influence of apparatus of the present invention degassing mouthful duration of congestion

Elastomer solution

* 2: the degassing mouthful

* 3: the shared weight percent of the vinylbenzene in the elastomerics

＜embodiment 3 〉

Identical with embodiment 1, use Desolventizing apparatus (Fig. 5) and identical operations condition according to the inventive method, three kinds of elastomer solution d, e, f(concentration and the solvent for use handled in the comparative example 2 still are respectively 20%(weight) and hexane).Measure degassing mouth in beginning to be operated to the time that obstruction is experienced, and according to comparative example 2 described " visible gel determination method " analyzing and processing gained elastomerics, simultaneously also with it equally with 6%(weight) ratio be used for the modification of impact-resistant polystyrene, and observe the surface of resulting product.

Table 6 is the net effect of above test gained, and it shows the more sensitive elastomer solution of heat, when using device of the present invention to remove solvent, can as conventional art the problem that heat cross-linking causes elasticity to go bad not take place.

＜embodiment 4 〉

Except that main extruder 40 changes different turning to the closed jointing twin screw extruder PLABOR CONVERTWIN BT-30-C type into, all the other equipment, operational condition, and pending elastomer solution is all identical with embodiment 3.Gained the results are shown in table 7.Comparison sheet 6 can be found with table 7, uses the different forcing machine that turns to that the elastomeric gel content of gained is reduced.

By above explanation as can be known, the present invention has following advantage compared to existing technology:

Method and apparatus of the present invention can overcome really the insurmountable elastomerics of conventional art cross the rotten and degassing mouth of heat cross-linking stopped up by elastomer powder and

＜table 6〉synthesis result of three kinds of elastomer solutions various analyses and test before and after desolventizing

* 1: before desolventizing is handled

* 2: after desolventizing is handled

＜table 7〉synthesis result of three kinds of elastomer solutions various analyses and test before and after desolventizing

* 1: before desolventizing is handled

* 2: after desolventizing is handled

Palpus is the difficult problem of pausing operation often.The present invention and aforementioned Taiwan patent the 184th, No. 257 and United States Patent (USP) the 3rd, 917, the difference of No. 507 maximums, just be that drawing-in device is not only the intensification that utilizes static mixer to make elastomer solution and can finishes in less than 3 seconds, crosslinked to avoid elastomerics to take place because of heat-up time is long, more use simultaneously one to press down the complete tightly meshing double-screw feeder of (txtruding downwards) characteristic, before elastomerics is fed to main extruder, just remove most solvent earlier and prevent the effusion of elastomer powder with vacuum system binding and tool.

Claims

1. A method for removing solvent from a solution containing at least 8% (by weight) of an elastomeric polymer, which adopts the method of making the elastomer solution go through a pretreatment process to remove most of the solvent before feeding, and then Feed to the main extruder, use the screw of the main extruder to advance the elastomer solution, and use one or more degassing ports arranged along the feeding direction of the main extruder, and if necessary, between each degassing port Inject the degassing agent into the position between them, and remove the residual solvent. It is characterized in that: the pretreatment process is to use a static mixer to fully mix a warming fluid with the elastomer solution under high back pressure and rapidly Raise the temperature to 60-250°C, and then use a dispersing nozzle to spray the mixture of heating fluid and elastomer solution into a vaporization chamber with an enlarged space, causing the pressure to drop suddenly to vaporize most of the heating fluid and solvent, and the elasticity The solid is formed into powder and separated from it; the outlet end of the vaporization chamber is sealed by a closely meshing twin-screw feeder, and one end of the twin-screw feeder is connected to a vacuum system, and 20-95% (weight) of the total solvent can be used here. The other end of the tightly intermeshing twin-screw feeder is connected to the main extruder, and the elastomer formed into powder is fed into the main extruder by the rotation of the closely intermeshing screw feeder. extruder.

2. The method of claim 1, wherein the elastomeric polymer is selected from the group consisting of homopolymers of butadiene, isoprene, ethylene-propylene block copolymers, and vinyl aromatic and conjugated Diene copolymers, conjugated dienes can be partially hydrogenated or unhydrogenated compounds, and the elastomeric polymer can be styrene-butadiene and styrene-isoprene block copolymers or star copolymer.

3. The method as claimed in claim 1, characterized in that the heating fluid can be steam of water, hexane, cyclohexane, pentane, isopentane, benzene, toluene, ethylbenzene, acetone.

4. The method as claimed in claim 1, characterized in that: the vaporization chamber is an inclined diffuser or arc shape, and its inner wall is coated with a surface coating agent to prevent the adhesion of the elastomeric polymer.

5. The method according to claim 1, characterized in that the rotational speed of the closely intermeshing twin-screws is 50-300 rpm.

6. The method according to claim 1, characterized in that: the degassing port on the main extruder is a closely meshing twin-screw degassing port with a downward pressure design or a general degassing port.

7. The method according to claim 1, characterized in that: at least two of the degassing ports on the main extruder are closely intermeshing twin-screw degassing ports with a downward pressure design.

8. The method according to claim 1, characterized in that: the main extruder is a single-screw, twin-screw, or multi-screw extruder, and the rotation direction of the screws can be the same or reverse.

9. The method according to claim 1, characterized in that: the degassing aid is a medium-low boiling point solvent, including water, ethylbenzene, butane, pentane or hexane; and the amount of the degassing aid is 0.5-5% by weight of the elastomeric polymer.