CN100434251C

CN100434251C - Process and apparatus for pelletization of polymers

Info

Publication number: CN100434251C
Application number: CNB2004800219545A
Authority: CN
Inventors: R·A·杰克逊; D·J·罗耶; M·G·沃戈纳
Original assignee: EI Du Pont de Nemours and Co
Current assignee: Ticona LLC
Priority date: 2003-07-30
Filing date: 2004-07-28
Publication date: 2008-11-19
Anticipated expiration: 2024-07-28
Also published as: CN1829591A

Abstract

An improved process for the pelletization of polymers is disclosed, using a die in which the die holes incorporate a reverse taper along at least a portion of the length thereof. Conditions for operation of an under melt cutter incorporating this die are also disclosed. The die plate (1) has an exit face (2), where the polymer (not shown) exists the die (hole), and an entrance face (3) where the (molten) polymer enters the die hole (4). In this particular instance, (4) is straight over part of its length, zone 5, and has a reverse taper over part of its length, zone 6. The tapered portion has a 'taper angle' (8).

Description

The prilling process of polymer and equipment

Invention field

The present invention relates to the starting of fused mass granulating machine under water or cutting machine.More particularly, the present invention relates to have the mouth mould of back taper easy and quick start the method for this class comminutor and cutting machine at mouth mould outlet side with nib.The invention still further relates to a kind of improvement mouth membrane module design of the cutting machine of melt under water.

Background of invention

Thermoplastic (TP) is very important industrial goods.They generally are configured as various parts or shape with the melt forming method, promptly melt TP, are configured as certain shape when taking advantage of its fusion, make this TP be cooled to solid so that it " is fixed " in that shape then.In most of melt forming machines, TP is with spherolite or fine-grained form feeding, and size is generally in 0.1～about 0.7cm (full-size) scope.For most of melt forming machines are turned round effectively, preferred spherolite or particulate flow freely and have a size quite uniformly.

Developed the equipment of multiple granulation TP.Preferred such equipment should be with low-cost production even and runny pellet.A kind of comminutor of this class be so-called " melt cutting machine under water " (UMC), see for example U.S. patent 2,918,701 and 3,749,539.As UMC during by proper handling, it can produce a large amount of even and free-pouring TP pellets.But UMC has many shortcomings, and comprising TP that is difficult to granulation fusing point higher (＞200 ℃) or the opposite TP that is frozen into solid easily, the incompatibility process abnormality as the interruption in short-term of polymer flow, and is difficult to starting sometimes.Therefore wish to improve, with this class and other difficulty that reduces UMC as far as possible.

U.S. patent 4,728, and 276 have described " underwater pelletizer " that a kind of nib can be regarded inverted cone shape as.Not mentioned this nib is to the effect of starting.

Japanese patent application 5-253997 has described a kind of mouth mould of nib band back taper.The purpose in this class hole can be regarded the mould that will as far as possible reduce in non-UMC cutting machine as and dripped and degrade.

Therefore the objective of the invention is to provide a kind of mouth mould of cutting machine under water that is applicable to, it can reduce and the relevant difficulty of UMC starting as far as possible.These and other objects of the present invention, characteristics and advantage with prescription will become more and more clear to detailed description of the present invention with reference to following as disclosed herein.

Summary of the invention

This paper openly and prescription be a kind of method of starting melt cutting machine under the polymer water, wherein, molten polymer is forced by the mouth mould of exit face and one or more nibs is arranged, and at described polymer when described nib comes out by one or many rotating knife is cut, and wherein said polymer is to contact under water or with water near the exit face of described mouthful mould, and wherein the improvement of being done comprises:

(a) provide one or more nibs the mouth mould, wherein said nib band back taper and described mouthful of mould will remain on the fusing point of described polymer or higher temperature near the described back taper of at least a portion of described nib, perhaps, if described polymer does not have fusing point, then described part will remain on the glass transition point of described polymer or higher temperature, and described exit face contacts with water simultaneously.

(b) rotate described cutter; And

(c) at (a) and (b) finished after, force described molten polymer to contact at least 5 seconds with described exit face at described water, preferably after at least 10 seconds by described nib.

The invention still further relates to melt cutting machine mouth membrane module under water, it has mouth template or mouthful die body, it contains the nib that one or more molten polymers flow through and a polymer exit face is arranged, wherein improve and comprise described polymer exit face and contact with nonmetal heat guard, heat guard has first face far away, its face with the described polymer exit face of contact is relative, described first face far away contacts with gripper shoe, described gripper shoe has second face far away, its face with the described nonmetal heat guard of contact is relative, and described second face far away contacts with high-abrasive material.

This patent also discloses the method that the above-mentioned melt under water of a kind of usefulness cutting machine mouth membrane module carries out melt cutting under water.

The present invention will be more readily understood with reference to this paper accompanying drawing.

The accompanying drawing summary

Fig. 1 is the partial cross section figure of melt cutting machine mouth mould under water, the back taper nib in the signal mouthful mould.

Fig. 2 is identical with Fig. 1, but signal mouthful mould add optional part.

The section X-X of Fig. 3 (a, b and c) and Fig. 3 a signal a kind of with embodiment 1-6 in the similar mouthful mould of used mouthful of mould.

Fig. 4 and Fig. 2 are similar, but signal is with the preferred configuration of the UMC mouth mould of cooling water thermal insulation in mouth mould and the water-bath.

Detailed Description Of The Invention

UMC is to the unusual useful device of the granulation of polymer especially TP.The problem that this equipment exists is their polymer that starting is difficult, consuming time and frequent waste is being cut.So-called " starting " is meant the starting after shutting down for a long time or according to plan at UMC here, or the technology of short period shut down as flow at polymer in mouthful mould in short-term in have no progeny reset.From the starting of this class temporary stoppage, this paper also is referred to as " resetting ".Therefore UMC often with continuous or approximate continuous operation but not the mode of intermittently operated use, in intermittently operated, can exist between than the short operation cycle and shut down.

When the polymer flow by nib stopped, the polymer that is just being cut in UMC generally can freeze at the port of export of nib, because cold water has contacted this polymer.Typical rerun routine comprises the following steps:

1) stops water circulation (but polymer has frozen in the nib exit).

2) retract the car of supporting cutting machine blade and recirculated water.

3) in that time that water withdraws from, the polymer regular meeting refuse in the nib also begins hydrostomia, so want wiping mouth die face to remove the hydrostomia polymer.

4), then preferably some polymer were purged blow down valve and/or nib in the polymer feeder sleeve if polymer is not heat-staple.

5) clean-up port die face once more.

Then soon

6) allow trailer return position and it is fixed on the mouth membrane module.

7) press down automatic starting button, with quick order (several seconds at the most) water is recycled to a mouthful mould exit face, the rotation of starting cutting blade also makes polymer begin to flow.If can not carry out with accurate order in a short period of time, then UMC freezes once more possibly and/or a large amount of uncut polymer occur on trailer, and/or cutting blade may be snarled.

More than the program of Xiang Shuing has many shortcomings, comprising:

-in purging and hydrostomia process, lose polymer.

-this method is consuming time and frequent more much longer than the cause of shutting down, thus the loss production time.

-be difficult to operate safely UMC, because the operator will be exposed to hot-melt polymer and/or from the smog of hot-melt polymer, and/or itself may be hot (can scald the people) cooling water, and/or come the polymer of self-heating mouth mould or smog may be on fire (especially when the fusing point of polymer is very high).

Use specific mouth mould, the present invention has avoided all the problems referred to above greatly, especially resets.Some other characteristic that the present invention utilizes the back taper nib to add UMC provide and are easy to starting.So-called " back taper nib " is meant the nib of mouth template (polymer) outlet side than big along the remainder diameter of nib, and when nib from the exit face of mouth template to (polymer) of mouth template when inlet face moves nib diminish gradually and be the hole of smaller szie.This class nib need be all not tapered on the whole length of nib, but must be tapered at the mouth template outlet side.The degree of depth of awl is generally at least about 0.5cm～about 5cm.So-called " degree of depth of awl " is meant length along the hole axle (as distinguishing 26,29 and 31 length among the length in district 6 among Fig. 1 or Fig. 2).Be pointed out that the many UMC mouth moulds shown in the document all have the nib that reduces to the exit face cross section from inlet face, therefore in the present example, term " back taper " is meant the mouth mould of nib cross section increase in the same direction.

Fig. 1 illustrates the cross section of part mouth template, and this cross section is by the center line of back taper nib.Mouth template 1 has polymer (not signal) to export the exit face 2 of mould (hole) and the inlet face 3 that (fusion) polymer enters nib 4 there there.In this specific examples, 4 length in its district 5 partly are straight, and in the length in its district 6 back taper are arranged partly.Become wimble fraction that " cone angle " 8 is arranged.Though be not critical, preferably this cone angle is at least 0.1 °, more preferably at least about 0.2 °, and especially preferably at least about 0.5 °, and very preferably at least about 1.0 °.Also preferred this cone angle is about 10 ° or littler, more preferably 5 ° or littler, and especially preferred about 3.0 ° or littler.Should understand and to make up above any minimum and maximum cone angle to provide preferred cone angle scope.

Cone angle can change, but is not big discontinuous variation preferably, and arrives at 2 o'clock from 3 via 4, and cone angle should keep identical or increase.If cone angle is constant, then cone angle is exactly the formed angle in relative both sides by nib in the district 6, and this cone angle is included in the plane that comprises this nib axle simultaneously.If cone angle changes and in different sections different value is arranged, then each section should be determined similarly.Cone angle also can change consistently, and in the case, the cone angle of any point will be in a similar manner measured with the straight line perpendicular to 4 the conical surface on this aspect.

Generally, the nib as 4 has the circular section, but the cross section also can be other shape.This class on-circular cross-section can be got any in the multiple shape, only is subjected to these shape processing or the ability of making the import template are limited, and can form back taper along its length as long as have the nib of selected shape.General such inverted cone segment will be consistent with the shape of nib remainder.The cross section of inverted cone segment is general consistent with the cross section of hole remainder, but this is also nonessential.Preferred circular section.The representative diameter of circular section is about 0.05～about 0.7cm.

Nib can not be an en-block construction, that is to say, it can be can't help single piece of material and form.For example, if a mouthful mould will be used for the very strong composition of abrasiveness, as contain glass those, then nib can partly be formed by the plug-in unit in mouth die body and mouthful die body, and plug-in unit is made by high-abrasive material such as tungsten carbide.Plug-in unit can form the whole or partial-length in hole.In any case the cone angle of whole nib and back taper configuration comprise the part that is formed by plug-in unit, must satisfy necessary restriction as herein described, also preferably have preferred feature as herein described.

Fig. 2 signal is similar to the nib of Fig. 1, comprises mouth template 20, and it has the polymer (not shown) to go out the exit face 21 of nib and the inlet face 23 that (fusion) polymer is gone into nib 24 there there.In this specific examples, 24 is straight in its partial-length 25 scopes, and in its partial-length 26 scopes back taper is arranged.24 23 and near also have " normally " awl sections 27, it can help polymer flow in some cases.On surface 21 and be in contact with it and have with the hole of 24 conllinear be heat insulation layer 29, it makes the water thermal insulation in mouthful mould and the water-bath.29 outer surface 30 and high abrasion resistance and having with the material layer 31 in the hole of 24 conllinear contacts.31 play the wear-resistant surface effect that contacts with UMC cutter (not shown).Cutter 31 this surface or near cutting polymer.If have 29 and/or 31, the hole of then passing these parts also should preferably be inverted cone shape.If 29 and/or 31 is extremely thin, then there is not back taper can obviously not influence a mouthful mould performance yet.In other words, back taper should extend to polymer from 24 surfaces of coming out and/or being cut from the somewhere in 20.

The advantageous variant of mouth membrane module shown in Figure 2 is shown in Fig. 4, and this figure is the sectional view that is similar to Fig. 2, but Fig. 2 only illustrates the core of mouth template.This modification can use mouthful mould (assembly) of the mouth mould (assembly) in band back taper hole or band straight hole or " normally " taper hole to be used for the technology of UMC granulation TP.Therefore, Fig. 4 illustrates mouth template 60, and it has the exit face 61 of polymer (not shown) depanning there (hole) and the inlet face 63 that (fusion) polymer is gone into nib 64 there.In this specific examples, 64 are being straight on its whole length and on its close partial-length of 61 plug-in unit 65 are being arranged.65 have inverted cone segment on its most of length.On surface 61 and be in contact with it and have with the hole of 64 conllinear be preferably nonmetallic heat insulation layer 69, it plays a role in insulation between the water of mouth mould and water-bath and hole with 64 conllinear is arranged.69 have outer surface 70, and it contacts with stronger material layer 72 on the structure.72 have outer surface 73, and it contacts with having excellent wear and have with 71 (being referred to as stiff dough sometimes) in the hole of 64 conllinear.71 play the effect of the wear-resistant surface that contacts with UMC cutter (not shown).Cutter is at this surface or near cutting polymer it of 71.

Pass

69,71 and 72 hole and also should preferably be inverted cone shape.If 69 and/or 71 and/or 72 is extremely thin, then there is not back taper can obviously not influence the performance of mouthful mould yet.In other words, back taper should extend to polymer from 64 surfaces of coming out and/or being cut from the somewhere in 60.

In Fig. 4,69 can be fragility and/or low-intensity material, because it is nonmetallic materials such as mica, glass or pottery, thermoplastic or thermosetting resin (all these should have high melt point, thereby can not melt under mouth modulo operation temperature or softening) preferably.This means 71 (itself can be fragility) are connected on mouthful die body that for example, the bolt with passing 69 may be a problem, under the best circumstances because 69 and/or 71 cracking or other structural failure take place probably very much.For avoiding this problem, 71 materials (72) that will be connected to strong (and not crisp relatively) on the structure for example connect by soldering, melting welding or bolt as on steel or other metal.72 usefulness can be connected to mouthful die body or be connected to a mouthful die body by the collar (not shown) that is bolted to mouth template 60 by 69 (not shown) bolts then.In other words, can regard 71 gripper shoe to 72 as, be installed between the more weak and/or crisp nonmetal heat guard 69 and 71.The attendant advantages of this configuration is to make 69 and/or 71 to change easily, if for example, wish to change mold hole dimension (diameter) to produce the pellet of different size.

Preferred 69 thermal conductivity (by 69 thickness directions) is about 3W/m ° K or littler, more preferably from about 1.0W/m ° of K or littler.69 should be thick to being enough to not take place be cooled water " cold excessively " in bathing of mouthful die body.If use the back taper nib, this means that heat that mouthful membrane module can provide is enough to make mouthful mould can be with the above-mentioned starting of simplifying procedures.If there is no the back taper nib only means that then mouthful mould can be by the usual manner operation of UMC mouth mould.Thickness depends on the configuration that is cut polymer (particularly melt temperature), mouthful mould, the power and the other factors of mouthful mould heater, is easy to determine by simple experiment.72 should thickly make the very little needed structural strength of 71 fracture tendencies to being enough to provide, and can determine with the common mechanical design principle.

The cutting machine of the melt under water mouth membrane module of type shown in Figure 4 can be used to the usual manner cutting thermoplastic so that the melt cutting machine is commonly used under water.The improvement of this mouthful die body thermal insulation allows when water contacts with exit face than quiet run (for example the chance freezed of polymer is less) and/or cuts high-melting-point polymer etc.

So-called " water contacts with exit face " is meant that water directly contacts with exit face or water contacts with a certain parts, and these parts itself contact with exit face or it is by contacting and contact with exit face with one or more other parts.For example, water can contact with exit face 2 in Fig. 1.In Fig. 2, if there is no 29 and 31, then water can contact with mouth mould exit face, if having 29 but do not have 31, then water can contact with 29, if and if only exist 31 and do not have 29 or the both exist, then water can contact with 31.Under all these situations, think that all water contacts with exit face.

When not having back taper, then the hole of the port of export can be straight.If the mobile of polymer stops, then water is at the port of export or near the polymer in the contact hole and make polymer freeze (solidifying) it.Even the polymer in mouth die body inside still keeps fusion, also can hinder polymer at the solid polymer of hole exits end and flow again, unless it is melted.Come out to force the solid tamper though can apply enough (very) high pressure, equipment just has to make anti-this pressure and can be shockingly expensive.Therefore need aforementioned more complicated and the progress of starting sequence of difficulty.

But, when there is back taper in the hole, the preferred somewhere (with reference to figure 1) that only need be melted in the district 6 of polymer, solid polymer just can be easy to " jump out suddenly " from the hole, and conical plug of extraordinary image can be extracted from bottle.Therefore, in most of the cases need only with the obtainable more medium pressure of existing equipment.This especially resets with regard to having simplified starting greatly, and this point will be described as follows.

In continuity method, one of most of common causes that cause the UMC shutdown are that of short duration (for example, the reaching 1 hour) in the prilling process shut down.For example, shutdown may be the electricity of arbitrary part in the system or mechanical failure, polymer feeding pipeline or the solid grain obstruction of handling pipeline etc. and causing.Use contains the mouth mould in back taper hole, and then UMC itself, particularly water circulate, mouthful mould heats and the rotation of cutter can keep not stopping.Polymer near mouthful mould exit face can freeze, if but be still fusion at nib inverted cone segment somewhere polymer, then polymer flow can be reset after of short duration shutdown and UMC will often reset simply.May produce some out-of-size particles, and they can separate by size classes.If it is just not very good and disorderly closedown is not too of short duration at the polymer thermostable of granulation; then possibly molten polymer and/or solid particle are migrated out from first-class product up to removed all possible degradation polymer from system, perhaps also can the temporary close heater.This program is simple, save time and the loss of polymer few.

In batch technology, shut down or at least polymer flow interruption batch with criticize between usually be specially.Under this class situation, the easy starting characteristics of this mouthful mould obviously also are advantages.

For the shutdown of long period or the starting over a long time, as the maintenance of mapping out shuts down, and then program can be slightly different.If cutting is similar polymers before and after shutting down, if especially polymer is heat-staple, what for to clearing up UMC.UMC, especially mouth template and polymer treatment pipeline can reheat simply and can be from the mouth template hole connect water before the hydrostomia and rotating knife gets final product at polymer.(suppose in the nib inverted cone segment some polymer melt) at least and the remainder of system are ready to when mouth template reaches operating temperature, then can connect the polymerization logistics.Even if, then also can use this program because of the polymer that is cut is not that extreme heat is stablized thereby temporary stoppage also needs the cooling vent mould.If nib has been cleared up sky, then before being exposed to mouth mould exit face in the water, in the hole, put some molten polymers (for example, use the molten polymer mold filling, they may solidify) into.The preferred water that do not allow enters melt polymerization conduit after nib does not especially enter the hole, because (overheated) steam can be discharged nib consumingly.After in nib, polymer having been arranged, can start UMC and granulating system as mentioned above.

Other modification and the method for starting are conspicuous for the technical staff, also can adopt.

Point out that as above the optimum condition of starting is in the back taper district that is nib molten polymer to be arranged to small part district 6 (with reference to figure 1) easily.Realized this point,, meaned that also heat and the polymer because of polymer in the mouth mould and mouthful calligraphy or painting model body loss reached balance from the heat that mouth mould heater obtains, especially in district 6 even then there is not polymer flow.Near the exit face (2) of mouth mould or its, the main heat loss of mouthful mould and nib interpolymer with come close to or in contact with 2 water and be exposed to or the polymer surfaces of the close nib port of export relevant.But because polymer and most polymers composition are good heat guards, the heat loss of each section of nib interpolymer more and more far becomes fewer and feweri with the polymer surfaces that leaves contact water.Therefore, if mouth template (1) itself especially near nib, keeps enough heat, just can be to the enough heats of polymer supply so that it is keeping fusion to small part district 6.The measure that raising provides hot-fluid to polymer (in other words, tend to keep the hotter and fusion of polymer) comprise higher die temperature, 1 material have higher thermal conductivity, mouthful mould to add hot fluid higher circulation rate (seeing below), longer district 6 are arranged, for reducing 1 heat loss thermal insulation etc., vice versa.Minimizing provides the measure of the ability of enough heats to be included between melting point polymer or glass transition temperature and the water temperature the bigger temperature difference to polymer, and (in fact this often means, the fusing point of polymer or glass transition temperature are high more, it is difficult more then to keep in the district 6 polymer to be in molten state), vice versa.By these factors of balance, add a few experiments, just be easy to make up the UMC system of easy starting.

Here, during starting, near nib, mouthful mould should be in or be higher than the fusing point of polymer, especially to small part district 6, be in the back taper district.If polymer does not have fusing point (for amorphous), then should be in or be higher than the glass transition temperature of polymer around the nib.If polymer has a more than fusing point or glass transition temperature, then will be with peak melting point or maximum glass transition temperature.Fusing point and glass transition temperature are measured with ASTM method D 3418.Fusing point is got the maximum of fusion heat absorption, and glass transition temperature is got the mid point of transformation.Fusing point and glass transition temperature adopt post bake to measure.Preferably when starting, near the die temperature the nib exceeds at least about 5 ℃ than the peak melting point of polymer, more preferably at least about 10 ℃, especially preferably at least about 20 ℃.In order to quicken starting process, the control temperature of " pulse " mouthful mould heater is useful with rapid raising die temperature in short-term, if especially used polymer is heat-staple.If with amorphous polymer (first fusing point), near the die temperature when then preferably starting the nib exceeds at least about 25 ℃ than the maximum glass transition temperature of polymer, more preferably at least about 50 ℃, especially preferably at least about 100 ℃.

So-called " fusing ", " fusion " or " liquid state " polymer are meant that here temperature is in or is higher than the polymer of its peak melting point, if or polymer do not have fusing point (being unbodied), be meant the polymer that is in or is higher than its maximum glass transition temperature.Molten polymer can be with several different methods well known in the art by " pressure " through port mould and nib, for example, use pump,, molten polymer is pressurized to (as being higher than the interior air pressure of jar that part is full of molten polymer) on the environmental pressure as gear pump or helicoidal pump; Or induce mobile with extruder or gravity.The mouth mould can heat with any method known in the art.For example, can heat: cycle through the hot fluid (gas and/or liquid) of mouthful mould, reach as saturated or superheated steam, various deep fat with following means

And similar substance; And/or electric heater inner at the mouth die body or externally, as outside band heater and/or inner cartridge heater.

Can both cut with this method for solid and any polymer that can be melted more than 0 ℃.The melt viscosity of polymer preferably can be easier to be forced through in the scope of nib at molten polymer.

Polymer type that is suitable for and the particular polymers in these types comprise: polyester, as poly-(terephthalic acid (TPA) alkylene ester), as poly-(PETP), poly-(terephthalic acid (TPA) 1, the 3-propylene diester), poly-(terephthalic acid (TPA) 1,4-fourth diester), poly-(M-phthalic acid/terephthalic acid (TPA) alkylene ester); Poly-(2, the 6-alkylene naphthalate) are as poly-(2,6-naphthalenedicarboxylic acid second diester); Terephthalic acid (TPA), 1, the copolymer of 4-cyclohexanedimethanol and copolyesters thereof; Polyamide is as nylon-6, nylon-6,6; The copolymer of the especially linear alpha-olefin of polyolefin such as polyethylene, polypropylene, polystyrene, ethene and alpha-olefin, ethene and (methyl) acrylate and/or methacrylic acid and/or acrylic acid copolymer and salt thereof, and the copolymer of above-mentioned alkene; Acrylonitrile-butadiene-styrene copolymer; Fluorinated polymer comprises copolymer, the copolymer of polytetrafluoroethylene (PTFE), (per) fluoropolymer, poly-(PVF), ethene and vinylidene fluoride and poly-(vinylidene fluoride); Poly-(ether imide); Polysulfones is as PPSU; Polysulfide is as poly-(diphenyl sulfide); Poly-(ether-ketone); Poly-(ether-ether-ketone); TLCP is as polyester, poly-(esteramides) and poly-(ester-acid imide); And poly-(vinyl chloride).Also can be with two or more blend and/or other each polymer and/or polymer type wherein.

Used polymer can contain the normal any additives that adds in the thermoplastic polymer in the inventive method, as filler, reinforcing agent, pigment, antioxidant, plasticizer, fluorescent whitening agent, antiozonant, dyestuff and heat stabilizer.The concrete material that is suitable for comprises carbon (graphite and non-graphite), fiber and fento, organic fiber, fento and fibrid such as the aramid fiber and the liquid crystal polymer fibre of glass, the microballon of fibers form, mill glass and the fiber of milling, clay, mica, talcum powder and other mineral matter, powder type, titanium dioxide, powdered-metal, short metal wire and fiber and powder organic substance such as thermosetting polymer.These materials can be present in the above-mentioned composition with usual amounts.

The front view of Fig. 3 a signal mouthful mould and the section (XX) of this mouthful mould.This mouthful mould has a mouth die body 41, and it has inlet face (surface) 42,43,8 chambeies of exit face (surface) (be used for discharge heater) 44, bolt hole (being used for installing 41) i.e. 47 and 8 nibs 48 in 45 and 46,2 chambeies (being used for installing thermocouple).Fig. 3 b signal is fit to 48 nib plug-in unit carriage 49.Fig. 3 c signal is fit to 49 plug-in unit 50.

Separate piece

49 and 50 have been arranged, just be easy to change the effective diameter of nib.With reference to section (XX) and Fig. 3 b and the 3c of figure 3a, molten polymer enters 50 near 42, via 50 flow to 43 near, and near 43, leave 50.On near 43 50 ports of export or near the heat guard 43 or to be used for the wearing face of adjacent its rotation of cutter all not shown.All materials of 41,49 and 50 all should have high thermal, promptly＞and 50W/m ° K.In some cases, preferred 50 not only have high thermal, and have higher wearability, and (high heat conductance) tungsten carbide (60-170W/m ° of K) is suitable for this application.Mouth other part of mould that may exist or its connector such as assembling bolt, electric heater, thermocouple, fixedly the chuck etc. of electric heater is all not shown.As can coming into plain view from these figure, from electric heater promptly mouthful mould thermal source to 50 the inner surface that contacts molten polymer a high thermal conductance path is arranged.Be pointed out that, though electric heater often is designed to contact as far as possible its chamber wall,, have one little the air gap between the heater and 41 in some place, be the purpose of this paper, still part some higher thermal conductivity path regarded as in this usually inevitable gap.

Also be pointed out that, Fig. 3 c illustrated a band back taper the mouth mould plug-in unit (seeing below), its cone angle is 2.00 °.

Embodiment

Method

Use a mouthful mould A in some embodiments.This mouthful mould is used The AL-15 level is made.This mouthful mould mouth mould similar (except that some inessential small physics changed, the characteristic of this mouthful mould was identical with Fig. 3's) and overall diameter to that indicated in the drawings is 22.86cm and thick 6.35cm.This mouthful mould is screwed to the extruder end.8 equally spaced nibs are equipped with mouthful mould plug-in unit as 50, or are plugged so that the nib of operating is less than 8.Mouth mould plug-in unit is made by tungsten carbide.The mouth mould has also disposed heat guard and carbon steel gripper shoe that one deck is made by titanium carbide on the exit end face of nib.The gross thickness of titanium carbide and gripper shoe is 4.75mm.In plug-in unit 50, cone angle 8 (see figure 1)s are 2 °, and being similar to 5 district has 6.13cm long, and cone angle (not being back taper) is 1.724 °, being similar to 6 district has 6.99mm long, comprises the thickness (nib by these layer thicknesses also has back taper) of tungsten carbide and steel bracing plate layer.At the nib arrival end, diameter is 5.54mm, is 3.94mm at the port of export (in the outside of titanium carbide) diameter.

Use a mouthful mould B in some embodiments.This mouthful mould is made by carbon steel.This mouthful mould and mouth mould shown in Figure 3 are similar, and except that some inessential small physics changes, but exit face, heat guard, gripper shoe, stiff dough and plug-in unit are all as shown in Figure 4.Its overall diameter is 22.86cm, and thick is 4.20cm.This mouthful mould is bolted to the extruder end.8 equally spaced nibs are equipped with mouthful mould plug-in unit as 66, maybe can be plugged so that the nib of operating is less than 8.Mouth mould plug-in unit is made by 360 brass.Mouthful mould plug-in unit has 3 ° back taper in the 1.1cm length range, and at the outer surface of stiff dough, the diameter in hole is 0.549cm.Nib (in the mouth die body) diameter is 0.775cm.The thick 0.424cm of TiC stiff dough, carbon steel gripper shoe total thickness is 0.305cm, and mica heat guard thick about 1.3mm by compression the time.

Used some polymer in an embodiment, these polymer are as shown in table 1.All these polymer (except the LCP) all can be from E.I.DuPont de Nemours﹠amp; Co., Inc., Wilmington, DE, USA obtains.

Table 1

The polymer trade mark	Polymer	Filler ^＊＊(weight %)
The polymer trade mark	Polymer	Filler ^＊＊(weight %)
Rynite ^＊5246	PET	Glass fibre (35)+rubber toughening agent
Rynite ^＊5246	PET	Glass fibre (35)+rubber toughening agent	Rynite ^＊5253	PET	Glass fibre (45)
Rynite ^＊530	PET	Glass fibre (30)	Rynite ^＊5253	PET	Glass fibre (45)
Rynite ^＊530	PET	Glass fibre (30)	Rynite ^＊415HP	PET	Glass fibre (30)+rubber toughening agent
Rynite ^＊FR515	PET	Glass fibre (30)+fire retardant	Rynite ^＊415HP	PET	Glass fibre (30)+rubber toughening agent
Rynite ^＊FR515	PET	Glass fibre (30)+fire retardant	Zytel ^＊70G35	Nylon-6,6	Glass fibre (35)
Delrin ^＊100	Acetal [poly-(formaldehyde)]	Do not have	Zytel ^＊70G35	Nylon-6,6	Glass fibre (35)
Delrin ^＊100	Acetal [poly-(formaldehyde)]	Do not have	LCP	^＊＊＊	Do not have
Zytel ^＊70G33	Nylon-6,6	Glass fibre (33)	LCP	^＊＊＊	Do not have

^*Registration mark

^*Do not comprise a small amount of additive such as antioxidant

^{* *}Derived from quinhydrones/4,4 '-bis-phenol/terephthalic acid (TPA)/2, the liquid crystal polyester of 6-naphthalene dicarboxylic acids/4-hydroxybenzoic acid (50/50/70/30/320 mol ratio).

Embodiment 1～6

In these embodiments, adopt the mouth mould A that contains 8 nibs to come each polymer formulators of granulation underwater.In all cases, nib all has 2 ° back taper.Extruder with the melt polymer composition is fed to a mouthful mould to polymer.The melt temperature of extruder interpolymer remains under the temperature that polymer manufacturer recommends (or being higher than fusing point).Interrupt flowing of polymer constantly and allow it to freeze at some at the nib port of export.Reset melt cutting machine (suppose wherein existing polymer) then, method is to connect cutting car (comprising cutter and cooling water), plays the circulation of moving knife and cooling water, and die temperature is raised near the melting point polymer.Start the polymer feed extruder; and beginning feeds extruder polymer; being configured on the polymer feed extruder port of export is set makes molten polymer not advance the valve of swinging to of comminutor, molten polymer is fed comminutor (mouthful mould) and begun granulation at the moment.In some cases, when starting polymer feeding, be raised to required final speed then gradually with slower speed starting.In all listed embodiment of table 2, even mouthful mould starts also smooth in recirculated water.With the progress of starting sequence of such simplification, the starting polymer flows through the required pressure of mouthful mould and is shown in Table 2, and provides steady state pressure, mouthful mould and the temperature of cooling water and used polymer between granulation stage simultaneously.

Table 2

Embodiment 7

Adopt melt cutting machine mouth mould under the 50 hole industry waters of a band back taper nib.This mouthful die body is made by carbon steel and a mouthful die body is heated by resistive the device heating.Assemble each nib, make each nib all put into two nib linings.At inlet face (being similar to 42 among Fig. 3 a) is that long 3.58cm (1.41 inches), Circularhole diameter are the straight hole lining of 3.00mm (0.118 inch), is called entrance.The downstream of adjacent this entrance (polymer flow) is that long 2.53cm (0.995 inch), Circularhole diameter are the outlet section of 4.06mm (0.160 inch).The port of export of outlet section be flush and take actinal surface (being similar to 43 among Fig. 3 a) out of, and be exposed in the cooling water of comminutor.Outlet section can change, and the hole is straight or back taper is arranged.If back taper is arranged, its formation method can be: straight hole is hinged into required cone angle, and it is dark to make cone angle extend to 6.35mm (0.25 inch) from exit face.With gear pump molten polymer is fed comminutor mouth mould.Polymer be liquid crystal polymer (LCP) and be by quinhydrones/4,4 '-bis-phenol/terephthalic acid (TPA)/2, the copolymer that the 6-naphthalene dicarboxylic acids/the 4-hydroxybenzoic acid is made by 50/50/70/30/320 mol ratio, its fusing point are about 335 ℃.

Be the starting polymer flow, be heated to the mouth mould that is full of polymer more than the fusing point of LCP and polymer () fusing at mouthful mould upper reaches.The cutting car that contains rotating knife and water-bath (fill water and carry out the water circulation) in place.After the mouth mould is fully heated, open gear pump.Measurement is opened a mouthful mould (promptly starting polymer) and is flowed needed pressure, but the pressure of report may be more lower slightly, because pressure pulse may take place.

When outlet section contained straight hole, the pressure that need to surpass about 13.8MPa (2000psi) be opened a mouthful mould, if a mouth mould open entirely because there is fashion not open.In addition, coolant water temperature must be maintained at about 90 ℃ or higher to allow nib to open.This is a safety problem, because the very easy scald of such hot water operator.The maximum pressure that can produce safely in system is about 16.5MPa (2400psi).When with this mode operation, finally must change gear pump, and believe that this damage is to cause because of high starting pressure.Observe indirectly, have in 50 holes in mouthful mould and manyly usually do not opened by this method, its result granule size under standard granulation condition changes.

When existing back taper and (falling) cone angle to be 2 °, starting occur in about 10.3～13.8MPa (1500～2000psi), observe, as if gear pump can not damaged by this class starting.Also observe when starting most of nibs and opened, though not all nib all open, and granule size obviously even many (comparing) with straight hole.This performance is to obtain with about 60 ℃ or lower coolant water temperature.

When (falling) cone angle is 3 °, notice that the hole count of opening once more shows have many holes not open originally.Begin the starting (with heat the mouth mould) before, remove cutting car and observe the nib end.Discovery is partly freezed at outlet section at some hole interpolymers, and back taper has reduced there.Its result has contacted with the polymer of outlet section straight length.This shows, for each polymer composition that will cut under specified criteria, needs to determine the cone angle and the awl segment length of optimum operation.This is easy to by normal experiment, determines with the nib plug-in unit especially.

Embodiment 8-10

In these embodiments, employing has the mouth mould B of 2 nibs to come the various polymer formulators of granulation underwater.In all cases, the back taper of nib is 3 °, and melt cutting machine coolant water temperature is 53 ℃.Extruder with the melt polymer composition is fed to a mouthful mould to polymer.Interrupt polymer flow constantly and allow polymer to freeze at some at the nib port of export.Reset (suppose wherein existing polymer) melt cutting machine then, method is to connect cutting car (containing cutter and cooling water), plays the circulation of moving knife and cooling water, the mould temperature rise to design temperature.Starting polymer feed extruder also begins polymer is fed to extruder.Set being configured on the polymer feed extruder end and make molten polymer not advance the transfer valve of comminutor, molten polymer is fed comminutor (mouthful mould) and started granulation at the moment.In some cases, when starting polymer feeding, start with lower speed, and then be raised to required final speed gradually.In all listed embodiment of table 3,, start also smooth even a mouthful mould is in recirculated water.The required pressure of progress of starting sequence starting polymer flow through molds with this change is listed in table 3, also provides steady state pressure, outlet mould and coolant water temperature and used polymer between granulation stage simultaneously.

Table 3

^*Registration mark

Claims

1. the method for melt cutting machine under the starting polymer water, wherein molten polymer is forced through the mouth mould of exit face and one or more nibs, and described polymer when described nib comes out by one or many rotating knife is cut, and wherein said polymer is to contact under water or with water near the exit face of described mouthful mould, and wherein the improvement of being done comprises:

A, provide one or more nibs the mouth mould, described nib has back taper and described mouthful of mould will remain on the fusing point of described polymer or higher temperature near the described back taper of at least a portion of described nib, perhaps, if described polymer does not have fusing point, then the described part of the described back taper of described nib will remain on the glass transition point of described polymer or higher temperature, described exit face contacts with water simultaneously

B, rotate described cutter; And

C, after a and b have finished, force described molten polymer described water with after described exit face contacted at least 5 seconds by described nib.

2. the method for claim 1, the cone angle of wherein said back taper is 0.5 °～5 °.

3. as any one described method in the above claim, wherein Zhui the degree of depth is 0.5cm～5cm.

4. method as claimed in claim 1 or 2, the diameter of wherein said nib are 0.050cm～0.7cm.