CN1047126C - Extruding shaper for superhigh molecular weight polymer - Google Patents
Extruding shaper for superhigh molecular weight polymer Download PDFInfo
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- CN1047126C CN1047126C CN94107408A CN94107408A CN1047126C CN 1047126 C CN1047126 C CN 1047126C CN 94107408 A CN94107408 A CN 94107408A CN 94107408 A CN94107408 A CN 94107408A CN 1047126 C CN1047126 C CN 1047126C
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- screw
- screw rod
- molecular weight
- high molecular
- extruder
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
- B29C48/25—Component parts, details or accessories; Auxiliary operations
- B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
- B29C48/50—Details of extruders
- B29C48/505—Screws
- B29C48/535—Screws with thread pitch varying along the longitudinal axis
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
- B29C48/25—Component parts, details or accessories; Auxiliary operations
- B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
- B29C48/50—Details of extruders
- B29C48/505—Screws
- B29C48/53—Screws having a varying channel depth, e.g. varying the diameter of the longitudinal screw trunk
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Extrusion Moulding Of Plastics Or The Like (AREA)
Abstract
The present invention relates to an extrusion molding machine for an ultra high molecular weight polymer, which can be used for ultra high molecular weight polyethylene or high-adhesiveness materials. The present invention comprises a combined type screw rod, a machine barrel and an extruder head, wherein a coverage layer of teflon filling modified material is arranged on the surface of the screw rod of the extruder and the inner wall of the machine barrel; the screw rod adopts the structural parameter with the small lead angle and the major diameter; screw threads of combined screw rods are staggered and discontinuous. Thus, the extruder solves the problem that due to great adhesive force and easy degradation by shear, the ultra high molecular polymer can not molded by extrusion. The continuous extrusion molding of the extra high molecular polymer can be realized.
Description
The present invention relates to plastic processing machinery, particularly relate to the screw extruder of super high molecular weight polymer and high adhesivity material.Can be used for the extrusion molding of ultra-high molecular weight polyethylene.
Super high molecular weight polymer (as ultra-high molecular weight polyethylene) has superior mechanical and physical performance and chemical stability, but its viscosity height, melt index (MI) are extremely low, approach zero, poor mobile performance, very easily degraded under high-rate of shear is so be one of focus of plastic processing circle contention for a long time to the processing of ultra-high molecular weight polyethylene.
To the processing of ultra-high molecular weight polyethylene, majority adopts the sintering process moulding at present, and also useful plunger-type extruder is pushed and produced goods, but these goods mostly are the bar of simple shape.Also rare with this based article of screw extruder extrusion molding.Because common screw rod extruding ultrahigh molecular weight polyethylene is very difficult, generally squeeze not come out, even it is quite big to extrude the power of post consumption.Reason is that the viscosity of this material is high, is easy to stick on the contact-making surface of metal screw and machine barrel, and frictional resistance is excessive.And be based upon the theoretic common screw parameter of shearing plasticizing ultra-high molecular weight polyethylene is very easily degraded under the high-rate of shear effect, material is extruded not easy-formation.Proposing a kind of extrusion method of high viscosity low-density polymeric in the EP78515 patent, mainly is the coat that scribbles low-friction coefficient at the feeding section of screw rod, as polytetrafluoroethylene (PTFE), and uses metal 101 alloy-coated on machine barrel.Close with it patent also has JP53-6366, JP4-18321 etc.More than each patent be not the technical scheme that proposes at the processing request of ultra-high molecular weight polyethylene, but solve LLDPE in solid granulates shape or reinforced mobile poor, problem that transfer efficiency is low when Powdered, so mainly be to reduce the coefficient of friction of material to screw rod, particularly feeding section is to the coefficient of friction of screw rod, the processing characteristics of this and ultra-high molecular weight polyethylene requires to differ far away, because:
(1) be 1 as the LLDPE melt index (MI) of putting down in writing in the document, flow rate 〉=22 are to≤32, and the ultra-high molecular weight polyethylene different material kind that is holding of TPO, melt flow rate (MFR) is extremely low to approach zero, and its high viscosity shows fusion or critical molten condition, and this moment, the external friction power that particularly adhesive attraction caused was excessive if the external friction power in the processing is excessive, make the material appearance and produce strong the shearing inside, and cause and be detained thickening of boundary layer.This very easily causes degraded for the ultra-high molecular weight polyethylene of anti-shear rate not.If the scheme by documents only scribbles coating at feeding section and obviously still can not solve above-mentioned processing problems.
(2) though according to extruding principle as can be known, extruding of material is the spiral shell rib propelling of frictionally by screw rod, but the propelling key of experimental study proof material not each skin-friction coefficient absolute value, and be that material is to the total frictional force of screw channel and the material difference to the total frictional force of machine barrel, promptly two skin-friction coefficients will have certain difference, are pushed into to guarantee the material machine tube inner wall that can recline.For the linea low density polymer of general viscosity, this difference is big more, helps improving the propelling speed of material more.But to super high molecular weight polymer under the high viscosity of plastifying state, this difference is excessive, as only on screw rod, scribbling coating in the documents, machine tube inner wall still keeps big coefficient of friction, then will cause the blocked up material lagging boundary layer of machine tube inner wall, be unfavorable for that material advances, and has widened material Residence Time Distribution in machine.
(3) above-mentioned patent is not sheared the theoretic screw rod parameter of plasticizing and is not made improvement being based upon, and certainly will be sheared when extruding ultrahigh molecular weight is polymer-extruded and produces signs of degradation.
Task of the present invention is exactly that a kind of screw extruder that meets the super high molecular weight polymer processing request will be provided, high-viscosity material when assurance is in fusion plastification does not adhere to gluing to screw rod and machine barrel contact-making surface, and good sliding is arranged all, avoid the super high molecular weight polymer material to be subjected to high shear forces, material is fully moulded roll and cut mixing, continuous extrusion than stranding.
For achieving the above object, the present invention takes following technical scheme.
Critical piece of the present invention comprises machine barrel and is contained in the interior assembled screw rod of machine barrel.It is characterized in that:
(1) coating of the filling-modified composite of polytetrafluoroethylene (PTFE) is arranged at least on screw rod and plastifying material contact-segment surface and corresponding machine tube inner wall respectively, the coefficient of friction of screw surface coating is less than the coefficient of friction of machine tube inner wall coating.The purpose of this measure is to increase the high-viscosity material that the is in molten condition sliding to screw rod and machine barrel simultaneously, and it is gluing that material and screw rod and barrel surface are not taken place.Concerning the extruding of super high molecular weight polymer, solve material the adhesion ratio of surface of the work is improved coefficient of friction, power etc. are more important.Can avoid the group material in the screw channel like this owing to cause upper and lower speed difference, produce extra shearing and degrade with the adhesion of screw rod.Prevented that also material is to the undue adhesion of machine barrel and form thicker border retention layer.To continuous extruding ultrahigh molecular weight polymer is very favourable.The coefficient of friction size of screw rod and barrel surface obtains by the ratio of adjusting filler in the coating.
(2) the screw rod parameter adopts little lift angle, major diameter structure, and lift angle is got 8-12 °, and diameter is at φ 200 1 φ 400mm, and black screw slenderness ratio is 4-6.Because diameter is big, screw speed is got low speed, is 5 one 20rpm.The selection of above parameter and common plasticizing shearing principle differ widely.It has increased the thrust of spiral shell rib to material under the prerequisite that does not reduce linear speed, reduced crossing current, avoids material to be subjected to lateral shear and degrades.Little lift angle then guarantees stable the extruding when coefficient of friction changes slightly.
(3) screw rod is combined by a plurality of screwing elements, and each screwing element angle that interlaces makes the screw thread on the whole screw rod discontinuous during combination.Like this, material group in the leading portion screw channel is divided into two halves in entering follow-up screw thread, to expect that group's core comes out, and the original surface that is about to fusion is combined into one by follow-up screw thread, become the material heart, so material keeping the plasticizing admixture in whole screw rod progradation, through " branch ", " closing " stream repeatedly, the core of material is brought in constant renewal in, and reaches the purpose that is mixed.
Feature of the present invention also is:
Above-mentioned screw rod and the coating on the machine barrel adopt the filling-modified composite of polytetrafluoroethylene (PTFE), and its filler consists of: (by volume)
Bronze powder 35-60%
Glass fibre or glass dust 15-20%
Graphite, molybdenum bisuphide≤5%
The coating of screw surface and machine tube inner wall is all selected in above component; As long as select different set of dispense ratios, can guarantee to make the coefficient of friction of the coefficient of friction of screw surface less than machine tube inner wall.In general, select more glass fibre (or glass dust) or/and less graphite can obtain bigger coefficient of friction, otherwise then obtain less coefficient of friction.The adding of bronze powder can improve the thermal conductivity on surface.
Screw channel on the above-mentioned screw rod is the square sectional that is bordering on big fillet root angle, and material integral body in screw channel is rolled, and group closes.
Effect of the present invention:
Owing in screw surface and machine tube inner wall the filling-modified composite material coating of polytetrafluoroethylene (PTFE) is arranged simultaneously, increase material to each surperficial sliding, solved one of difficult point that super high molecular weight polymer with high viscosity extrudes--additional shear that bonding force brings and the material circle retention problems on the machine tube inner wall.
The selection of screw-rod structure parameter is avoided, has been reduced crossing current effectively and shears, and has solved super high molecular weight polymer and has been sheared the problem of easy degraded.
In a word, the present invention has been different from the shearing plasticizing theory of common extruder on extruder mechanism, and has adopted low speed kneading, integral body to roll stranding, divide to collaborate to plastify and mix; Make the continuous extrusion of super high molecular weight polymer become the reality of nature.At present ultra-high molecular weight polyethylene has successfully been carried out extrusion molding.
Open in detail below in conjunction with accompanying drawing to the present invention.
Fig. 1 is this extruder screw, machine barrel parts structure chart.
Fig. 2 is this extruder combined threaded rod structural representation.
Fig. 3 is the partial enlarged drawing of screw channel shape among Fig. 1.
As Figure 1-3: this screw extruder critical piece comprises combined threaded rod and is contained in the outer machine barrel 11 of screw rod, and extruder head 10, and wherein combined threaded rod is made up of multistage screwing element 1,2,3,4,13.The centre has a Hollow Transmission Shafts 12 each section screwing elements to be assembled on the hollow shaft 12 by the long key 6 that leads, and is driven by hollow shaft and rotates, and rotating speed is between 5-20rpm.The activity of going back in the middle of the hollow shaft installs a rotating mandrel 7, and its rotation direction and rotating speed are regulated by another transmission system or motor.
For the super high molecular weight polymer with high viscosity (ultra-high molecular weight polyethylene) that overcomes molten state in sight adheres to screw rod and machine barrel, this extruder on material contact- segment 1,2,3 surfaces and corresponding barrel section inwall of screw rod and plasticizing, has the filling-modified material of one deck polytetrafluoroethylene (PTFE) covering layer at least.Specifically, except the feeding section of screw rod, on other parts of screw rod and the corresponding machine tube inner wall this coating is arranged all.This coating contains fillers such as bronze powder, glass fibre or glass dust, graphite, molybdenum bisuphide.It makes screw surface and machine tube inner wall that not viscosity all be arranged well, has kept good resistance to compression creep, wearability simultaneously again.And the existence of bronze powder has improved surperficial thermal conductivity, is necessary because of consuming the more high-power heat that produces when extruding distributing high-viscosity material.For the coefficient of friction that guarantees the screw surface coating is lower than the coefficient of friction of machine tube inner wall coating, screw rod of this machine and barrel surface coating contain following filling mixture ratio: (by with the volume ratio of polytetrafluoroethylene (PTFE))
Screw surface coating machine barrel internal coated layer bronze powder 30% 40% glass fibres 20% 20% and glass dust graphite, molybdenum bisuphide 5% 3% is according to the different material requirement, and above proportioning can be regulated.With overlying strata is to be laminated with up with general sintering process, and also available method of attaching is laminated with, and this point those skilled in the art can implement.
In addition, should not shear the processing request that is subjected in order to meet ultra-high molecular weight polyethylene, this extruder has changed the conventional screw rod parameter of setting up by shearing the plasticizing theory, adopts little lift angle, major diameter structure, and screw rod is that lift angle is 10.Multiple-threaded screw, draw ratio 5, diameter is φ 250mm.Lead angle begins to reduce gradually to extruding zone from feeding section.The purpose of little lift angle is to increase forward thrust stable extrude of spiral shell rib to material.Reduce crossing current component or cross shear.Improve output in a sense.Screw rod adopts combined threaded rod, during each screw flight element combination, and the certain angle that interlaces, half screw channel that can stagger is wide, makes the screw thread on the whole screw rod discontinuous.The material group that the front screw channel comes out is by follow-up spiral shell rib cleave in two, and the material heart is brought in constant renewal in by follow-up multiple thread with the surface, makes to be in promptly the material of molten state and to be in plastifying state all the time and to mix, rub with the hands and roll homogenizing, until extruding.
It is darker that screw channel on the screw rod is opened, and the degree of depth is in 2/3-1 pitch.Employing has the square cross-sectional configuration that is bordering at big fillet root angle, makes material be subjected to integral body to roll stranding, is not subjected to or reduces shearing.
This extruder also has following structure except that above-mentioned improvement.
Adopt the plug of mandrel as extruding pipe material, do not have shunt line and seam when making high-viscosity material be extruded into tubing, mandrel slowly runs when extruding, and melting charge is evenly flowed.
Whole combined threaded rod diminishes to the extruding zone lead angle gradually from feeding section, and screw channel narrows down gradually, to adapt to the performance variation of material.Screw front end is a band spiral fluted transition conehead 8, with corresponding machine barrel tapering point 9 formation gaps.The mandrel termination stretch into head 10 also with its formation gap.Like this, by rotation mandrel and interstitial structure cause material by the time certain head resistance is arranged, play the effect of regulating materials flow.
For guarantee the advancing of material, roll, twisting, open longitudinal groove at machine tube inner wall and make material and machine barrel spiral shell do on assigned direction external frictions such as its mechanicalness microcosmic collision of increase.
The mandrel end also can have screw channel, so that material is replenished plasticizing.
Head is made tubulose or sheet, is used to extrude the goods of different shapes.The head inner chamber also can have the filling-modified composite material coating of polytetrafluoroethylene (PTFE), reduces material and adheres to.The tubulose head is rotatable, cooperates the rotation of mandrel to eliminate the flow liner that screw rod brings.
Claims (6)
1, a kind of extrusion shaping machine of super high molecular weight polymer comprises assembled screw rod, is set in outer machine barrel (11) extruder head (10) of screw rod, it is characterized in that:
(1) layer that covering of the filling-modified material of one deck polytetrafluoroethylene (PTFE) is arranged at least on screw rod and beginning material contact surface of plastifying state and corresponding machine barrel (11) section inwall, and the coefficient of friction of screw surface coating is less than the coefficient of friction of machine tube inner wall face coating,
(2) screw rod adopts little lift angle, major diameter structure, and lift angle is at 8 °-12 °, and screw diameter is φ 200-φ 400mm, screw slenderness ratio 4-6,
(3) screw rod is combined by a plurality of screwing elements (1), (2), (3), (4), (13), and the fashionable angle that interlaces of the thread set on each screwing element makes the screw thread on the whole screw rod discontinuous.
2, extrusion shaping machine according to claim 1, it is characterized in that: on screw surface and the machine tube inner wall face to cover layer be the filling-modified material of polytetrafluoroethylene (PTFE) that contains following filling mixture ratio, press the volume ratio bronze powder 35-60% glass fibre of polytetrafluoroethylene (PTFE) or glass dust 15-20% graphite, molybdenum bisuphide≤5%
3, extrusion shaping machine according to claim 1 is characterized in that, the screw channel on the screw rod is the square sectional that approaches with big fillet root angle, and spiral groove depth is a 2/3-1 pitch.
4, extrusion shaping machine according to claim 1 is characterized in that: screwing element adopts multiple thread.
5, extrusion shaping machine according to claim 1 is characterized in that: screw front end is a band spiral fluted transition conehead (8), with corresponding machine barrel tapering point (9) formation gap.
6, extruder according to claim 1 is characterized in that: head (10) inner chamber also has the layer that covering of the filling-modified material of polytetrafluoroethylene (PTFE).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN94107408A CN1047126C (en) | 1994-07-18 | 1994-07-18 | Extruding shaper for superhigh molecular weight polymer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN94107408A CN1047126C (en) | 1994-07-18 | 1994-07-18 | Extruding shaper for superhigh molecular weight polymer |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1115280A CN1115280A (en) | 1996-01-24 |
| CN1047126C true CN1047126C (en) | 1999-12-08 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN94107408A Expired - Fee Related CN1047126C (en) | 1994-07-18 | 1994-07-18 | Extruding shaper for superhigh molecular weight polymer |
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| Country | Link |
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| CN (1) | CN1047126C (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101531054B (en) * | 2009-04-28 | 2012-07-04 | 张家港市杰达机械制造有限公司 | Extrusion device of conical twin-screw extruder special for polyolefine |
| CN101920841A (en) * | 2010-08-19 | 2010-12-22 | 吴汉民 | Complex screw |
| CN102260917A (en) * | 2011-06-30 | 2011-11-30 | 山东大学 | High-efficiency screw dissolving equipment |
| CN105014919A (en) * | 2014-04-17 | 2015-11-04 | 奥卓海（上海）机械有限公司 | Single screw extruder of pure ultrahigh molecular weight polyethylene material |
| AT518550B1 (en) * | 2016-07-29 | 2017-11-15 | Andritz Ag Maschf | screw Press |
| CN106738590B (en) * | 2016-12-16 | 2023-01-17 | 浙江海峰自动化设备有限公司 | Casting head jacket for PU material |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS536366A (en) * | 1976-07-08 | 1978-01-20 | Oji Paper Co | Plastic melt extruding screw |
| EP0078515A1 (en) * | 1981-10-29 | 1983-05-11 | Union Carbide Corporation | Method for extrusion of linear polyolefin materials |
| CN2048820U (en) * | 1989-07-01 | 1989-12-06 | 北京化工学院 | Two-stage screw orbor for exhaust extruder |
| US5156790A (en) * | 1991-07-25 | 1992-10-20 | Union Carbide Chemicals & Plastics Technology Corporation | Method for extruding ethylene polymers |
-
1994
- 1994-07-18 CN CN94107408A patent/CN1047126C/en not_active Expired - Fee Related
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS536366A (en) * | 1976-07-08 | 1978-01-20 | Oji Paper Co | Plastic melt extruding screw |
| EP0078515A1 (en) * | 1981-10-29 | 1983-05-11 | Union Carbide Corporation | Method for extrusion of linear polyolefin materials |
| CN2048820U (en) * | 1989-07-01 | 1989-12-06 | 北京化工学院 | Two-stage screw orbor for exhaust extruder |
| US5156790A (en) * | 1991-07-25 | 1992-10-20 | Union Carbide Chemicals & Plastics Technology Corporation | Method for extruding ethylene polymers |
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| Publication number | Publication date |
|---|---|
| CN1115280A (en) | 1996-01-24 |
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