CN109435194B - Be used for thermoplastic polyester foaming forming device - Google Patents
Be used for thermoplastic polyester foaming forming device Download PDFInfo
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- CN109435194B CN109435194B CN201811534003.8A CN201811534003A CN109435194B CN 109435194 B CN109435194 B CN 109435194B CN 201811534003 A CN201811534003 A CN 201811534003A CN 109435194 B CN109435194 B CN 109435194B
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- screw extruder
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- 238000005187 foaming Methods 0.000 title claims abstract description 48
- 229920000728 polyester Polymers 0.000 title abstract description 67
- 229920001169 thermoplastic Polymers 0.000 title abstract description 35
- 239000004416 thermosoftening plastic Substances 0.000 title abstract description 35
- 239000000155 melt Substances 0.000 claims abstract description 41
- 239000004088 foaming agent Substances 0.000 claims abstract description 20
- 238000002347 injection Methods 0.000 claims abstract description 15
- 239000007924 injection Substances 0.000 claims abstract description 15
- 238000001816 cooling Methods 0.000 claims abstract description 12
- 238000002156 mixing Methods 0.000 claims description 6
- 238000007789 sealing Methods 0.000 claims description 6
- 238000001125 extrusion Methods 0.000 abstract description 21
- 238000004519 manufacturing process Methods 0.000 abstract description 14
- 238000001035 drying Methods 0.000 abstract description 13
- 238000007493 shaping process Methods 0.000 abstract description 10
- 230000003068 static effect Effects 0.000 abstract description 9
- 238000005265 energy consumption Methods 0.000 abstract description 8
- 238000010097 foam moulding Methods 0.000 abstract description 7
- 238000006243 chemical reaction Methods 0.000 abstract description 6
- 239000002994 raw material Substances 0.000 abstract description 4
- 238000011112 process operation Methods 0.000 abstract description 2
- 210000000497 foam cell Anatomy 0.000 abstract 1
- 238000000034 method Methods 0.000 description 16
- 230000008569 process Effects 0.000 description 16
- 239000000654 additive Substances 0.000 description 6
- 239000000243 solution Substances 0.000 description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- 239000004970 Chain extender Substances 0.000 description 4
- 230000000996 additive effect Effects 0.000 description 4
- 230000015556 catabolic process Effects 0.000 description 4
- 238000006731 degradation reaction Methods 0.000 description 4
- 238000002844 melting Methods 0.000 description 4
- 230000008018 melting Effects 0.000 description 4
- 238000000465 moulding Methods 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- 230000007423 decrease Effects 0.000 description 3
- 230000007547 defect Effects 0.000 description 3
- 238000007872 degassing Methods 0.000 description 3
- 230000007062 hydrolysis Effects 0.000 description 3
- 238000006460 hydrolysis reaction Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 238000010008 shearing Methods 0.000 description 3
- 238000010521 absorption reaction Methods 0.000 description 2
- 239000012752 auxiliary agent Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000006260 foam Substances 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 238000006467 substitution reaction Methods 0.000 description 2
- 229920006230 thermoplastic polyester resin Polymers 0.000 description 2
- 241000251468 Actinopterygii Species 0.000 description 1
- 239000004604 Blowing Agent Substances 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 238000007605 air drying Methods 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000006085 branching agent Substances 0.000 description 1
- 239000001273 butane Substances 0.000 description 1
- 239000003431 cross linking reagent Substances 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 238000002036 drum drying Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- 229920002313 fluoropolymer Polymers 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- IJDNQMDRQITEOD-UHFFFAOYSA-N n-butane Chemical compound CCCC IJDNQMDRQITEOD-UHFFFAOYSA-N 0.000 description 1
- OFBQJSOFQDEBGM-UHFFFAOYSA-N n-pentane Natural products CCCCC OFBQJSOFQDEBGM-UHFFFAOYSA-N 0.000 description 1
- 231100000956 nontoxicity Toxicity 0.000 description 1
- 230000006911 nucleation Effects 0.000 description 1
- 238000010899 nucleation Methods 0.000 description 1
- 239000012071 phase Substances 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 239000004014 plasticizer Substances 0.000 description 1
- 238000006068 polycondensation reaction Methods 0.000 description 1
- 229920001225 polyester resin Polymers 0.000 description 1
- 239000004645 polyester resin Substances 0.000 description 1
- 238000010094 polymer processing Methods 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 238000010248 power generation Methods 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 239000000779 smoke Substances 0.000 description 1
- 239000007790 solid phase Substances 0.000 description 1
- 238000011144 upstream manufacturing Methods 0.000 description 1
- 238000009849 vacuum degassing Methods 0.000 description 1
Classifications
-
- 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
- B29C44/00—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles
-
- 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
-
- 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
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29K2075/00—Use of PU, i.e. polyureas or polyurethanes or derivatives thereof, as moulding material
Abstract
The invention relates to a foam molding device for thermoplastic polyester, which comprises: the device comprises a double-screw extruder, a melt pump, a static mixer, a foaming machine head, a forming and shaping device and a vacuum system, wherein the length-diameter ratio of double screws of the double-screw extruder is 35-45, a natural exhaust port, at least one vacuum exhaust port and at least one foaming agent injection port are formed in a double-screw machine barrel, the vacuum system is connected with the vacuum exhaust port on the double-screw machine barrel, the vacuum degree of a vacuum exhaust section of the double-screw extruder can be adjusted between 20Pa and 200Pa, and the device adopts a cooling system to control the temperature of the melt. The device is a drying-free reaction extrusion foaming integrated production device for thermoplastic polyester, the polyester raw material can be directly added into a double-screw extruder without drying, the energy consumption is reduced, the production efficiency is improved, the thermoplastic polyester foaming plate with low density, uniform and fine foam cell structure and large thickness can be stably produced, and the device has the advantages of high production efficiency, low energy consumption, easy process operation and high production stability.
Description
Technical Field
The invention relates to a polymer processing device, in particular to a foaming forming device for thermoplastic polyester.
Background
The thermoplastic polyester has excellent heat resistance and mechanical property compared with the prior artThe foamed plastic and the thermoplastic polyester foam have the advantages of good dimensional stability at high temperature, excellent mechanical property and fatigue resistance, low smoke, flame retardance, no toxicity, low water absorption, good gas barrier property, recycling and the like, and have wide application prospects in the fields of wind power generation, rail transit, automobile industry and the like. However, thermoplastic polyesters have low melt viscosity, poor thermal stability, and are susceptible to thermal degradation and hydrolysis of absorbed moisture, particularly hydrolysis, which can lead to a dramatic decrease in the molecular weight of the polyester; in order to overcome the defects of the thermoplastic polyester, the prior art mainly increases the viscosity of the polyester by adding a chain extender or a cross-linking agent, and can be added with a multifunctional auxiliary agent during polymerization and then subjected to solid phase polycondensation to obtain the thermoplastic polyester with high melt viscosity; or adding a multifunctional chain extender or branching agent in the extrusion process, and performing reactive extrusion to obtain the high-viscosity polyester. Aiming at the defects of water absorption and high hydrolysis of polyester, the prior art generally adopts a predrying technology to remove water in polyester chips. The pre-drying is usually carried out in three forms of vacuum drum drying, rotary filling combined drying and fluidized bed, continuous air drying is usually carried out at 140 deg.C for 3-4 hr, and the drying is carried out at 100-110deg.C or placed in a dry closed container for use, and the hopper is irradiated with infrared rays to maintain dry state, or N is used 2 Protecting the feeding device. The pre-drying process has the advantages of complex equipment, long drying process time consumption, low efficiency and high energy consumption.
To overcome this disadvantage, US 2015336319A1 discloses a polyester foaming extrusion device comprising: the device comprises a feeding system, a homodromous double-screw extruder, a machine head and a shaping device, wherein the double-screw extruder is provided with an air exhaust area and a vacuum exhaust area, the temperature of the air exhaust area is lower than the melting point of polyester by 10 ℃, the melt temperature of the vacuum exhaust area is higher than the melting point of polyester, and especially, preheated nitrogen is injected into a first exhaust area to enhance the air exhaust effect. The device can realize the drying-free direct extrusion processing of polyester, and overcomes the defects of time consumption, high energy consumption and complex equipment of a pre-drying process to a certain extent. But has the disadvantage of complex equipment and operations for injecting preheated nitrogen in the first exhaust zone.
CN201220654257.5 discloses a twin-screw sheet extrusion device for drying PET without crystallization, which comprises a feeding device, a screw extruder and a sheet extrusion device, wherein the screw extruder is a parallel twin-screw extruder with a plurality of vacuumizing devices arranged thereon. In order to improve the dehydration efficiency, the embodiment discloses that the absolute vacuum pressure of a vacuum pump is less than or equal to 0.5mbar and the degassing capacity is more than 1000l/s. The technical scheme is lack of adaptability for adding various low-molecular additive components in the polyester reaction extrusion foaming process, and the excessively high vacuum degree and degassing amount can cause the low-molecular additive (chain extender, plasticizer and the like) to be vacuumized away, so that the chain extension reaction efficiency is reduced, the viscoelasticity of polyester melt can not meet the foaming requirement, and the PET drying-free reaction extrusion foaming integrated production can not be realized.
US5958164 discloses a thermoplastic polyester foaming process comprising: directly adding polyester and additives into a first-stage double-screw extruder, removing water adsorbed by the polyester in a vacuum exhaust section on the double-screw extruder, then injecting a foaming agent, foaming in a downstream low-pressure area to obtain a PET foamed product, particularly adding fluoroplastic into the polyester, and injecting the foaming agent from an air injection port on a second-stage single-screw extruder, wherein the vacuum degassing pressure is lower than 20Torr (2666 pa). According to the technical scheme, the foaming agent (butane) is injected from the second-stage single-screw extruder, the diameter of the single screw is equal to that of the double screws, so that the foaming agent and the PET melt are fully mixed, the rotation speed of the single screw is high, high shearing heat is easy to produce during processing, the temperature of the PET melt cannot be accurately controlled, the extrusion process is unstable, the pressure of a machine head is low, and the like, and the foaming density is difficult to obtain to be lower than 200kg/m 3 And the thickness is more than 30 mm.
Disclosure of Invention
In order to realize efficient, stable and high-quality production of thermoplastic polyester foam molding, the invention provides a device for thermoplastic polyester foam molding.
According to one aspect of the invention, there is provided a foaming and forming device for thermoplastic polyester, comprising a twin-screw extruder, a melt pump, a single-screw extruder, a static mixer, a foaming machine head and a forming and forming device, wherein the length-diameter ratio of the twin screw of the twin-screw extruder is between 35 and 45, and a cylinder of the twin-screw extruder is provided with a natural exhaust port, at least one vacuum exhaust port and at least one foaming agent injection port; the diameter of a single screw rod of the single screw extruder is 1.5 times or more of the diameter of a double screw rod, the length-diameter ratio of the single screw rod is 15-30, and a cooling system is adopted to control the temperature of the single screw rod; the device also comprises a vacuum system, wherein the vacuum system is connected with a vacuum exhaust port of the double-screw extruder, and the vacuum degree of a vacuum exhaust section of the double-screw extruder can be adjusted between 20Pa and 200 Pa.
Preferably, in the above device, the diameter of the single screw is 1.5 to 3 times the diameter of the double screw.
Preferably, in the above device, the twin-screw extruder is provided with a feeding section, a natural exhaust section, a first sealing section, a vacuum exhaust section, a second sealing section, a gas injection section, a mixing section and a metering and conveying section, respectively, along the length direction.
Preferably, in the above apparatus, the melt pump is installed between the twin-screw extruder and the single-screw extruder.
Preferably, in the above apparatus, the rotational speed of the melt pump and the single screw extruder are automatically adjusted by a closed loop pressure feedback control system.
Preferably, in the above device, the foaming head is a fishtail type plate head, a ring head, a T-shaped sheet head or a porous strip head.
Preferably, in the above device, the length of the vacuum exhaust section of the twin-screw extruder is 10 to 18 times the diameter of the twin-screw.
According to another aspect of the invention, there is provided a foaming and forming device for thermoplastic polyester, comprising a twin-screw extruder, a melt pump, a melt cooler, a static mixer, a foaming machine head and a forming and forming device, wherein the length-diameter ratio of the twin screw of the twin-screw extruder is between 35 and 45, and the barrel of the twin-screw extruder is provided with a natural exhaust port, at least one vacuum exhaust port and at least one foaming agent injection port; the melt cooler is suitable for cooling the high-viscosity melt, and the temperature of the melt is controlled by the cooling system; the device also comprises a vacuum system, wherein the vacuum system is connected with a vacuum exhaust port of the double-screw extruder, and the vacuum degree of a vacuum exhaust section of the double-screw extruder can be adjusted between 20Pa and 200 Pa.
Preferably, in the above apparatus, the melt pump is installed between the twin screw extruder and the melt cooler.
Preferably, in the above device, the rotation speed of the melt pump is automatically adjusted by a closed loop pressure feedback control system.
Preferably, in the above device, the length of the vacuum exhaust section of the twin-screw extruder is 10 to 18 times the diameter of the twin-screw.
The invention provides a thermoplastic polyester foaming forming device, which is a thermoplastic polyester drying-free reactive extrusion foaming integrated production device, and can avoid pre-drying of polyester in a foaming process, and polyester raw materials can be directly added into a double-screw extruder without drying, so that the energy consumption is reduced and the production efficiency is improved. The device provided by the invention can stably produce the thermoplastic polyester foamed sheet with low density, uniform and fine cell structure and large thickness, and has the advantages of high production efficiency, low energy consumption, easy operation of the process and high production stability.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below.
Fig. 1 is a schematic view of a foam molding apparatus for thermoplastic polyesters according to a preferred embodiment of the present invention.
Fig. 2 is a schematic view of a foam molding apparatus for thermoplastic polyesters according to another preferred embodiment of the present invention.
Detailed Description
The invention discloses a foaming molding device for thermoplastic polyester, which comprises: the device comprises a double-screw extruder, a melt pump, a static mixer, a foaming machine head and a forming and shaping device, wherein the length-diameter ratio of double screws of the double-screw extruder is between 35 and 45, and a cylinder of the double-screw extruder is provided with a natural exhaust port, at least one vacuum exhaust port and at least one foaming agent injection port; the device also comprises a vacuum system, the vacuum system is connected with a vacuum exhaust port of the double-screw extruder, the vacuum degree of a vacuum exhaust section of the double-screw extruder can be adjusted between 20Pa and 200Pa, and the device adopts a cooling system to accurately control the temperature of the single screw.
Fig. 1 is a schematic view of a foam molding apparatus for thermoplastic polyesters according to a preferred embodiment of the present invention. As shown in fig. 1, the device comprises a multi-station feeding system (not shown), a double-screw extruder 1, a melt pump 3, a single-screw extruder 4, a static mixer 6, a foaming machine head 7, a forming and shaping device 8 and a vacuum system 2, wherein the melt pump 3 is arranged between the double-screw extruder 1 and the single-screw extruder 4, the static mixer 6 is arranged between the foaming machine head 7 and the single-screw extruder 4, and the forming and shaping device 8 is arranged at the downstream of the foaming machine head 7. Wherein, a natural exhaust port, at least one vacuum exhaust port and at least one foaming agent injection port are arranged on the machine barrel of the double-screw extruder, the vacuum system 2 is connected with the vacuum exhaust port of the double-screw extruder 1 through a pipeline, and the vacuum degree of the vacuum exhaust section of the double-screw extruder can be adjusted between 20Pa and 200 Pa.
The multi-station feed system of the apparatus is a weightless feed system and generally comprises at least one main feed system and at least one additive feed system. The main feeding system is preferably two, and the brand new thermoplastic polyester resin and the recycled thermoplastic polyester resin can be metered and fed according to set requirements. The additive feeding systems are preferably two, namely a chain extender feeding system and an auxiliary agent feeding system, more preferably three, respectively, so as to conveniently regulate and control the formula. The outlet of the feeding system is connected with the feed inlet of the double-screw extruder 1.
In the preferred embodiment shown in fig. 1, the device for foaming and forming the thermoplastic polyester adopts a double-stage extruder serial system, wherein the first stage is a double-screw extruder 1, the second stage is a single-screw extruder 4, the two extruders are connected in series by a melt pump 3, and the double-screw extruder 1 is a co-rotating double-screw extruder. The diameter D1 and the length L1 of the double screw rod of the double screw extruder 1 are provided with the functions of melting, exhausting, injecting foaming agent, uniformly mixing components and the like of the polyester resin, so that the functions can be better realized, the thermoplastic polyester is prevented from being thermally degraded, and the length-diameter ratio L1/D1 of the double screw rod of the double screw extruder 1 is between 35:1 and 45: and 1, a feeding section, a natural exhaust section, a first sealing section, a vacuum exhaust section, a second sealing section, a mixing section and a metering conveying section are respectively arranged along the length direction. If the aspect ratio of the twin-screw extruder 1 is less than 35:1, the vacuum exhaust section or the mixing section is too short to exhaust repeatedly and uniformly mix the foaming agent, so that the uniformity and stability of the extrusion foaming process are affected; if the aspect ratio is greater than 45:1, the thermoplastic polyester is easy to be subjected to serious thermal degradation, so that the melt viscosity of the polyester is greatly reduced, and an ideal foaming product cannot be obtained. In order to ensure the vacuum evacuation effect, the vacuum evacuation is preferably performed between 10D1 and 18D1, and more preferably between 12D1 and 15D1. The length of the vacuum exhaust section being greater than 18D1 can result in excessively long overall length-to-diameter ratio of the twin screw, and less than 10D1 can affect degassing. In the foaming process, the polyester raw material can be directly added into a double-screw extruder without drying, and adsorbed moisture is removed through a natural vent and at least one vacuum vent on the double-screw extruder.
The vacuum system of the device is a high vacuum system, which consists of a multistage vacuum pump, an extraction chamber and a condensing tank, and is connected with a vacuum exhaust port on the double-screw extruder 1 through a pipeline, and the high vacuum system can enable the vacuum degree of the vacuum exhaust section of the double-screw extruder to be lower than 200pa, and is preferably adjustable between 20 and 200 pa. The pumping rate of the high vacuum system is 100L/s to 500L/s, preferably 300L/s to 500L/s.
The main function of the second-stage single-screw extruder 4 is to uniformly cool the polyester melt containing the foaming agent fed from the twin-screw extruder 1 to T m -10℃≤T≤T m +30℃,T m For the melting point of the polyester, the chain extension reaction of the thermoplastic polyester (e.g., PET) is accomplished in a single screw extruder, with the apparatus employing a cooling system 9 for precise temperature control of the single screw. Not only requires the single screw of the single screw extruder 4 to have strong heat exchange capability to reduce the temperature of the melt to a temperature suitable for foaming, but also requires the temperature of the meltThe single screw rod has even parts, low shearing heat during rotation, and certain melt conveying capacity, so that the obtained foaming product has even structure and the extrusion process can be stably carried out. In order to achieve the object, the single screw extruder 4 according to the present invention has a single screw diameter D2 of L2 and a length L2, wherein the single screw diameter D2 is 1.5 times or more, preferably 1.5 to 3 times, more preferably 2 to 2.5 times the double screw diameter D1, and the single screw extruder 4 has an aspect ratio L2/D2 of 15 to 30. If the length-diameter ratio L2/D2 is smaller than 15, the cooling requirement cannot be met; if the length-diameter ratio L2/D2 is more than 30, the thermal degradation of the polyester is serious, the quality of the foamed product of the polyester is affected, and the aperture ratio is increased.
In the foaming process of thermoplastic polyester, the excessive pressure of the head of the double-screw extruder easily causes the increase of the resistance of materials in the double screw, the injection of foaming agent is difficult, in addition, the increase of shearing heat generated by the materials in the double screw is easy to generate thermal degradation, the quality of products is affected, and the difficulty in dissolving the foaming agent in polyester melt is caused by the excessively low pressure. In order to increase the nucleation density of the foamed article, it is generally desirable to have a sufficiently high head pressure, while the second stage single screw is mainly intended to lower the melt temperature, so that the melt conveying capacity is weak, especially for high-viscosity melts. In order to solve the above-mentioned problems, it is preferable that a melt pump 3 is installed between the twin-screw extruder and the single-screw extruder for adjusting the outlet pressure of the twin-screw extruder and the inlet pressure of the single-screw extruder to ensure stable operation of the extrusion process. As the polyester chain extension reaction proceeds, the melt viscosity increases sharply, the fluidity decreases, and the melt pump 3 is set to power the high-viscosity melt delivery, which is beneficial to the stable operation of the extrusion process. The rotation speed of the melt pump 3 can be manually adjusted by manpower, and also can be controlled by monitoring the pressure of the inlet and the outlet and adopting an automatic feedback control system. In order to ensure stable operation of the twin-screw extruder 1, it is necessary to make the melt pressure between the outlet of the twin-screw extruder and the inlet of the melt pump lower than 8MPa, preferably between 3MPa and 8MPa, and the actual pressure is collected into a control system by a pressure sensor, and the rotational speed of the melt pump 3 is controlled by a Programmable Logic Controller (PLC) program feedback of the control system. When the pressure at this point is lower than the set value, the control system automatically decreases the rotational speed of the melt pump 3, whereas when the pressure at this point is higher than the set value, the rotational speed of the melt pump 3 is automatically increased, so that the pressure at this point is stabilized at the set value. Similarly, a closed loop feedback system may be used to control the single screw speed to ensure that the single screw extruder inlet has a certain pressure value, e.g., any set point between 15MPa and 20MPa.
The foaming head 7 may be a fish tail type head, a ring head, a T-shaped sheet head or a perforated bar head. The foaming head 7 is connected with the outlet of the single screw extruder, so that the material flows in the foaming head and is uniformly distributed in the whole width direction.
A static mixer 6 can be arranged between the foaming machine head 7 and the single screw extruder 4, so that the temperature and the flow rate of the melt can be homogenized before entering the foaming machine head 7, and the stability of the extrusion process and the uniformity of the appearance and the quality of the product can be maintained.
The foaming agent injection system can be a liquid pump such as a plunger type liquid metering pump, a diaphragm pump, a piston pump and the like and is connected with an air injection valve on the double-screw extruder 1 through a pipeline. Preferably, a diaphragm pump or a plunger type metering pump is adopted, the pump has a certain explosion-proof grade, and the highest pressure of a pump outlet is more than or equal to 20MPa. Preferably, in the foaming process, the physical blowing agent is injected into the twin-screw polyester melt by means of an air injection system 5 shown in fig. 1 in connection with the twin-screw extruder 1.
Downstream of the extrusion system is provided a shaping device, as shown in fig. 1 a shaping device 8 is mounted downstream of the foaming head 7 for cooling the foamed polyester.
Fig. 2 is another preferred embodiment of the disclosed apparatus for foam molding thermoplastic polyesters, as shown in fig. 2, the apparatus comprising a twin screw extruder 1, a vacuum system 2, a melt pump 3, a melt cooler 10, a static mixer 6, a foam head 7, and a forming and shaping apparatus 8. The length-diameter ratio of the twin screw extruder 1 is between 35 and 45, a cylinder of the twin screw extruder is provided with a natural exhaust port, at least one vacuum exhaust port and at least one foaming agent injection port, the vacuum system 2 is connected with the vacuum exhaust port of the twin screw extruder 1, so that the vacuum degree of a vacuum exhaust section of the twin screw extruder can be adjusted between 20Pa and 200Pa, and the length of the vacuum exhaust section of the twin screw extruder 1 is 10 times to 18 times of the diameter of the twin screw; the melt pump 3 is arranged between the double-screw extruder 1 and the melt cooler 10, and the rotating speed of the melt pump 3 is automatically regulated through a closed-loop pressure feedback control system; the melt cooler 10 is adapted to cool down the high viscosity melt and to achieve accurate melt temperature control by means of the cooling system 9. The static mixer 6 is mounted upstream of the foaming head 7.
In a preferred embodiment of the apparatus as shown in fig. 2, the apparatus may further comprise a multi-station feeding system (not shown), a single screw extruder (not shown), and the like. In this preferred embodiment, the description of the parameters of the various components of the device and the setting of the parameters during use are the same as described above with reference to the device of fig. 1.
The process for extrusion foaming molding of thermoplastic polyester by using the device of the invention comprises the following steps: adding thermoplastic polyester and additives into an extrusion system consisting of a co-rotating double-screw extruder, a melt pump, a single-screw extruder, a high vacuum system, a foaming agent injection system, a forming and shaping device and the like through a multi-station feeding system; injecting a physical foaming agent into polyester melt in an extrusion system, forming a homogeneous phase solution through the mixing action of a double-screw extruder, then reducing the temperature of the polyester melt containing the foaming agent through a cooling system, extruding and foaming through a mouth die, and cooling and molding a foamed product on a molding and shaping device to obtain the thermoplastic polyester foamed product. The density of the obtained polyester foaming product is 60-300 kg/m 3 Between them.
The invention provides a thermoplastic polyester foaming forming device, which is a thermoplastic polyester drying-free reactive extrusion foaming integrated production device, and can avoid pre-drying of polyester in a foaming process, and polyester raw materials can be directly added into a double-screw extruder without drying, so that the energy consumption is reduced and the production efficiency is improved. The device provided by the invention can stably produce the thermoplastic polyester foamed sheet with low density, uniform and fine cell structure and large thickness, and has the advantages of high production efficiency, low energy consumption, easy process operation and high production stability.
The above examples are only specific embodiments of the present invention for illustrating the technical solution of the present invention, but not for limiting the scope of the present invention, and although the present invention has been described in detail with reference to the foregoing examples, it will be understood by those skilled in the art that the present invention is not limited thereto: any person skilled in the art may modify or easily conceive of the technical solution described in the foregoing embodiments, or perform equivalent substitution of some of the technical features, while remaining within the technical scope of the present disclosure; such modifications, changes or substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention, and are intended to be included in the scope of the present invention. Therefore, the protection scope of the invention is subject to the protection scope of the claims.
Claims (4)
1. The device is characterized in that the length-diameter ratio of double screws of the double-screw extruder is between 35 and 45, a natural exhaust port, at least one vacuum exhaust port and at least one foaming agent injection port are formed in a machine barrel of the double screws, and a feeding section, a natural exhaust section, a first sealing section, a vacuum exhaust section, a second sealing section, a gas injection section, a mixing section and a metering conveying section are respectively arranged in the double-screw extruder along the length direction, wherein the length of the vacuum exhaust section is 10-18 times of the diameter of the double screws; the diameter of a single screw rod of the single screw rod extruder is larger than or equal to 1.5 times of the diameter of the double screw rod, the length-diameter ratio of the single screw rod is 15-30, and a cooling system is adopted to control the temperature of the single screw rod; the device also comprises a vacuum system, wherein the vacuum system is connected with the vacuum exhaust port of the double-screw extruder, so that the vacuum degree of the vacuum exhaust section of the double-screw extruder is adjusted to be 20 Pa-200 Pa; the melt pump is mounted between the twin screw extruder and the single screw extruder.
2. The device of claim 1, wherein the diameter of the single screw is 1.5-3 times the diameter of the double screw.
3. The apparatus of claim 1, wherein the rotational speed of the melt pump and the single screw is automatically adjusted by a closed loop pressure feedback control system.
4. The apparatus of claim 1, wherein the foaming head is a fishtail type plate head, a ring head, a T-sheet head, or a porous strip head.
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| CN201811534003.8A CN109435194B (en) | 2018-12-14 | 2018-12-14 | Be used for thermoplastic polyester foaming forming device |
| PCT/CN2019/082361 WO2020118987A1 (en) | 2018-12-14 | 2019-04-12 | Foam molding apparatus used for thermoplastic polyester |
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| CN201811534003.8A CN109435194B (en) | 2018-12-14 | 2018-12-14 | Be used for thermoplastic polyester foaming forming device |
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| CN109435194A CN109435194A (en) | 2019-03-08 |
| CN109435194B true CN109435194B (en) | 2024-03-01 |
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| CN109435194B (en) * | 2018-12-14 | 2024-03-01 | 北京化工大学 | Be used for thermoplastic polyester foaming forming device |
| CN110435036B (en) * | 2019-08-16 | 2021-08-20 | 南通星辰合成材料有限公司 | Low-volatility and low-precipitation polyester material and preparation method thereof |
| CN113232225B (en) * | 2021-06-11 | 2022-09-16 | 荆门市双创专利技术服务有限公司 | EPS cystosepiment production line |
| CN113951372B (en) * | 2021-10-12 | 2023-12-22 | 哈尔滨良粟农业科技有限公司 | Double-screw extrusion equipment for producing high-moisture pure pea protein artificial meat |
| CN114316425B (en) * | 2021-11-25 | 2023-11-10 | 南通荣荟新材料科技有限公司 | Plant source multifunctional master batch capable of being thermoplastically processed and preparation method thereof |
| CN114130303B (en) * | 2021-11-27 | 2023-11-14 | 南京创博机械设备有限公司 | TGIC efficient devolatilization and melt extrusion granulation integrated processing method |
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| CN109435194A (en) | 2019-03-08 |
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