CN205553027U - Supercritical fluid extrudes foaming equipment - Google Patents

Abstract

A supercritical fluid foaming extrusion equipment, including a feeding device, a twin-screw extruder, a foaming agent injection system, a single-screw extruder, a melt pump and a molding die, wherein the feeding device, twin-screw extruder Extruder, blowing agent injection system, single-screw extruder, melt pump and molding die are connected in sequence. The setting of the melt pump can realize steady flow and pressurization, reduce the pressure fluctuation during the extrusion process, and ensure stable production quality. The specially designed shearing section and flow blocking section in the forming die ensure that the melt flow rate is uniformly distributed along the width direction of the sheet, and are conducive to forming a high pressure drop and pressure drop rate in the die, thereby obtaining microstructure and macroscopic Microporous foam sheet with excellent performance.

Description

A supercritical fluid extrusion foaming equipment

technical field

The utility model relates to an extruding and foaming device, in particular to a supercritical fluid extruding and foaming device.

Background technique

Compared with the traditional chemical foaming method, supercritical fluid extrusion foaming avoids the residual problem of chemical foaming agent in polymer materials, is more green and environmentally friendly, and has lower cost, so it is widely used in the production of microcellular foam Polymer Materials. Among them, supercritical CO ₂ extrusion foaming is an easy-to-scale production process, which can continuously and efficiently produce microcellular foamed pellets or plates with uniform and stable cell structure. In the prior art, in order to improve the mixing and dispersing effect and the accuracy of process parameter control, a twin-screw extruder and a single-screw extruder are generally used in series for extrusion foaming. However, the existing equipment is prone to melt pressure fluctuations during the extrusion and foaming process, and it is difficult to establish a high foaming pressure in the molding die, resulting in premature nucleation and growth of air bubbles in the die. The cell diameter of the foamed material becomes larger, and its macroscopic performance decreases. Especially when it is used to extrude foamed wide sheets, how to ensure that the melt flow rate at the exit die is evenly distributed along the width direction is still a difficult problem.

Utility model content

In order to solve the above problems, the purpose of this utility model is to provide a supercritical fluid extrusion foaming equipment, which includes a feeding device, a twin-screw extruder, a foaming agent injection system, a single-screw extruder and a molding die , the feeding device, twin-screw extruder, foaming agent injection system, single-screw extruder and forming die head are sequentially connected, and the forming die head includes sequentially connected fan-shaped areas, shearing sections, flow blocking sections and For the die lip, the cross-sectional area of the shearing section is smaller than the cross-sectional areas of the fan-shaped area, the choke section and the die lip, and the choke section has an S-shaped cross-sectional structure.

The supercritical fluid extrusion foaming equipment can be used for the continuous extrusion production of microcellular foaming materials of various thermoplastic polymer materials and their blends. The polymer raw material is fed into the twin-screw extruder through the feeding device, and melted and plasticized under the action of screw shear and external heating of the barrel. Then the supercritical fluid foaming agent is accurately metered through the foaming agent injection system and stably injected into the melt, and is fully dispersed and mixed with the melt under the high-speed mixing of the screw and the action of the shear force field. Next, the mixing system of foaming agent and melt is sent to a single-screw extruder, where it is further dispersed and mixed to form a homogeneous system of polymer melt/supercritical fluid foaming agent, and then cooled to a suitable temperature. The homogeneous system enters the forming die head, and in the forming die head, due to the sudden drop in pressure, the polymer melt/supercritical fluid foaming agent system reaches a thermodynamically unstable state, the cells nucleate and grow, and are finally cooled and shaped to obtain Microcellular foam sheet.

The shearing section in the forming die can ensure that the melt maintains a high pressure in the flow channel at the front of the die to avoid premature foaming of the material in the die. Among them, the choke section has an S-shaped cross-section, and there is a large pressure drop after the material enters the choke section flow channel through the shear section flow channel, so that CO ₂ is precipitated from the polymer melt, and the bubbles nucleate and grow. But at this time, there is still a high pressure in the die head, so the bubbles will not expand too much, and the material will exit the mold after passing through a shaping section, and the bubbles will further expand, and the microporous foam sheet product will be obtained after cooling and shaping. Moreover, the flow channel structure design of the shear section and the choke section is conducive to further uniform distribution of the flow velocity of the material along the width direction.

Further, the ratio of the cross-sectional area of the die lip to the cross-sectional area of the shear section is 1.1-15. The cross-sectional area of the blocking section is greater than or may be the same as that of the die lip.

Further, the ratio of the cross-sectional area of the die lip to the cross-sectional area of the shear section is 10.

Furthermore, the molding die has a coat-hanger-type runner structure, so that the cylindrical flow melt flowing from the barrel into the die becomes a flat flow melt with uniform flow velocity distribution, which is very suitable for the extrusion of sheets, especially wide sheets. forming.

Further, the supercritical fluid foaming basic equipment also includes a melt pump, and the feeding device, twin-screw extruder, foaming agent injection system, single-screw extruder, melt pump and molding die are sequentially connect. The homogeneous system enters the molding die after being stabilized and pressurized by the melt pump.

Further, the melt pump is a gear type melt pump.

Further, the feeding device is connected with the feeding port on the twin-screw extruder.

Further, the supercritical fluid foaming agent injection system is connected with the gas injection port on the twin-screw extruder. The gas injection port is located at the natural exhaust port of the twin-screw extruder, where the melt pressure in the barrel is relatively low, which is conducive to the stable and controllable injection of the blowing agent into the extruder. Moreover, the material in the barrel at the front end of the gas injection port has been completely melted and has a high melt pressure, which can form a melt seal to prevent the foaming agent from escaping to the feeding port, and the high melt pressure at the rear end of the gas injection port can also avoid foaming. After the foaming agent enters the extruder, it jets and flows.

Further, the foaming agent is supercritical CO ₂ .

Further, the blowing agent is supercritical _N2 or a mixture of supercritical _N2 and supercritical _CO2 .

The utility model provides a supercritical fluid foaming extrusion equipment, which has the following beneficial effects:

(1) The specially designed shearing section and flow blocking section in the forming die head ensure that the melt flow rate is uniformly distributed along the width direction of the material, and is conducive to forming a high pressure drop and pressure drop rate in the die head, thereby obtaining microscopic Microcellular foaming materials with excellent structure and macroscopic properties;

(2) The setting of the melt pump can realize steady flow and pressurization, reduce the pressure fluctuation in the extrusion process, and ensure stable production quality;

(3) The utility model can obtain a microcellular foaming material with a foaming ratio of more than 5 and an average cell diameter of less than 30um.

Description of drawings

The utility model further describes the embodiments in conjunction with the following drawings, wherein:

Fig. 1 is the structural representation of foam extrusion equipment of the present utility model;

Fig. 2 is a cross-sectional view of the molding die in Fig. 1 .

In the figure: 1-feeding device; 2-twin-screw extruder; 3-single-screw extruder; 4-melt pump; 5-forming die; 6-feeding port; 7-injection port; 8- Fan-shaped area; 9-shear section; 10-choke section; 11-die lip.

detailed description

Below in conjunction with accompanying drawing 1 and 2 the preferred embodiment of the present utility model is described.

Example 1

As shown in Figure 1, the supercritical fluid extrusion foaming equipment includes a feeding device 1, a twin-screw extruder ₂ , a supercritical CO injection system (not shown), a single-screw extruder 3, a melt pump 4 And forming die head 5.

During the working process, the polymer raw material is first fed into the twin-screw extruder 2 through the feeding device 1, and melted and plasticized under the action of screw shear and external heating of the barrel. Then, _CO2 is accurately metered and stably injected into the melt through the supercritical _CO2 injection system, and is fully dispersed and mixed with the melt under the high-speed mixing of the screw and the action of the shear force field. Then this mixed system is delivered to single-screw extruder 3, further disperses and mixes in single-screw extruder 3 to form polymer melt/supercritical _CO Homogeneous system and is cooled to suitable temperature, and this homogeneous system passes through The melt pump 4 enters the molding die head 5 after steady flow and pressurization. As shown in FIG. 2 , the molding die head also includes a fan-shaped area 8 , a shear section 9 , a flow blocking section 10 and a die lip 11 which are connected in sequence. Wherein the ratio of the cross-sectional area of the die lip 11 to the cross-sectional area of the shear section is 10, and the choke section 10 has an S-shaped cross section. The melt flows into the flow channels of the shearing section 9 and the blocking section 10 from the flow channel of the fan-shaped area 8 in sequence, and finally passes through the die lip 11 and exits the die head. Microcellular foamed material products with an average diameter below 30um.

Example 2

The supercritical fluid extrusion foaming equipment includes a feeding device 1, a twin-screw extruder ₂ , a supercritical CO injection system (not shown), a single-screw extruder 3, and a molding die 5.

During the working process, the polymer raw material is first fed into the twin-screw extruder 2 through the feeding device 1, and melted and plasticized under the action of screw shear and external heating of the barrel. Then, _CO2 is accurately metered and stably injected into the melt through the supercritical _CO2 injection system, and is fully dispersed and mixed with the melt under the high-speed mixing of the screw and the action of the shear force field. Then this mixed system is transported to single-screw extruder 3, further disperses and mixes in single-screw extruder 3 to form polymer melt/supercritical _CO Homogeneous system and is cooled to suitable temperature, and this homogeneous system enters Forming die head 5. As shown in FIG. 2 , the molding die head also includes a fan-shaped area 8 , a shear section 9 , a flow blocking section 10 and a die lip 11 which are connected in sequence. Wherein the ratio of the cross-sectional area of the die lip 11 to the cross-sectional area of the shear section is 10, and the choke section 10 has an S-shaped cross section. The melt flows into the flow channels of the shearing section 9 and the blocking section 10 from the flow channel of the fan-shaped area 8 in sequence, and finally passes through the die lip 11 and exits the die head. Microcellular foamed material products with an average diameter below 30um.

Example 3

As shown in Figure 1, the supercritical fluid extruding foaming equipment comprises the feeding device 1 that is connected with the feeding port 6 on the twin-screw extruder, twin-screw extruder ₂ , supercritical CO Injection system (not shown ), single-screw extruder 3, gear melt pump 4 and molding die 5.

During the working process, the polymer raw material is first fed into the twin-screw extruder 2 through the feeding device 1, and melted and plasticized under the action of screw shear and external heating of the barrel. Then, the supercritical _CO2 is accurately metered by the supercritical _CO2 injection system and stably injected into the melt through the gas injection port 7 on the twin-screw extruder, and is fully dispersed with the melt under the high-speed mixing and shear force field of the screw. mix. Then this mixed system is delivered to single-screw extruder 3, further disperses and mixes in single-screw extruder 3 to form polymer melt/supercritical _CO Homogeneous system and is cooled to suitable temperature, and this homogeneous system passes through The gear type melt pump 4 enters the forming die head 5 after steady flow and pressurization. As shown in Figure 2, the molding die 5 contains a coat-hanger-shaped runner structure, which can make the columnar flow melt flowing into the die from the melt pump 4 into a flat flow melt with uniform flow velocity distribution. The forming die also includes a fan-shaped area 8 , a shear section 9 , a flow blocking section 10 and a die lip 11 which are connected in sequence. Wherein the ratio of the cross-sectional area of the die lip 11 to the cross-sectional area of the shear section is 15, and the choke section 10 has an S-shaped cross section. The flat flow melt flows into the flow channel of the shearing section 9 and the blocking section 10 from the flow channel of the fan-shaped area 8 in sequence, and finally passes through a shaping section 11 before exiting the die head, and after foaming, cooling and shaping, the foaming ratio is above 5 , Microcellular foamed sheet products with an average cell diameter of less than 30um.

Example 4

As shown in Figure 1, the supercritical fluid extruding foaming equipment comprises the feeding device 1 that is connected with the feeding port 6 on the twin-screw extruder, twin-screw extruder ₂ , supercritical N Injection system (not shown ), single-screw extruder 3, gear melt pump 4 and molding die 5.

During the working process, the polymer raw material is first fed into the twin-screw extruder 2 through the feeding device 1, and melted and plasticized under the action of screw shear and external heating of the barrel. Then, the supercritical _N2 is accurately metered by the supercritical _N2 injection system and stably injected into the melt through the gas injection port 7 on the twin-screw extruder, and is fully dispersed with the melt under the high-speed mixing and shear force field of the screw. mix. Then this mixed system is transported to single-screw extruder 3, further disperses and mixes in single-screw extruder ₃ to form polymer melt/supercritical N Homogeneous system and is cooled to suitable temperature, and this homogeneous system passes through The gear type melt pump 4 enters the forming die head 5 after steady flow and pressurization. As shown in Figure 2, the molding die 5 contains a coat-hanger-shaped runner structure, which can make the columnar flow melt flowing into the die from the melt pump 4 into a flat flow melt with uniform flow velocity distribution. And the forming die head also includes a fan-shaped area 8 , a shear section 9 , a flow blocking section 10 and a die lip 11 which are connected in sequence. The ratio of the cross-sectional area of the die lip 11 to the cross-sectional area of the shear section is 1.1, and the choke section 10 has an S-shaped cross section. The flat flow melt flows into the flow channel of the shearing section 9 and the blocking section 10 from the flow channel of the fan-shaped area 8 in sequence, and finally passes through a shaping section 11 before exiting the die head, and after foaming, cooling and shaping, the foaming ratio is above 5 , Microcellular foamed sheet products with an average cell diameter of less than 30um.

Example 4

This embodiment is the same as Embodiment 3, except that the supercritical CO ₂ is replaced by a mixture of supercritical CO ₂ and supercritical N ₂ .

It should be understood that the above-mentioned embodiments of the present utility model are only examples for clearly illustrating the present utility model, rather than limiting the implementation manner of the present utility model. For those skilled in the art, on the basis of the above description, other changes or changes in different forms can also be made. All the implementation manners cannot be exhaustively listed here. All obvious changes or changes derived from the technical solutions of the utility model are still within the scope of protection of the utility model.

Claims (10)

1. a supercritical fluid foaming extrusion equipment, injects system including drawing-in device (1), double screw extruder (2), foaming agent System, single screw extrusion machine (3) and molding die (5)；Described drawing-in device (1), double screw extruder (2), foaming Agent injected system, single screw extrusion machine (3) and molding die (5) are linked in sequence successively, it is characterised in that described molding die (5) include the fan section (8) being sequentially communicated, shear section (9), choked flow section (10) and die lip (11)；Described shearing section (9) cross-sectional area is less than fan section (8), choked flow section (10) and the cross-sectional area of die lip (11)；Described choked flow section (10) There is S type cross-sectional structure.

Equipment the most according to claim 1, it is characterised in that the sectional area of described die lip (11) and the cross section of described shearing section (9) Long-pending ratio is 1.1-15.

Equipment the most according to claim 2, it is characterised in that the sectional area of described die lip (11) and the cross section of described shearing section (9) Long-pending ratio is 10.

Equipment the most according to claim 1, it is characterised in that described molding die (5) has clothes hanger type flow passage structure.

Equipment the most according to claim 1, it is characterised in that described supercritical fluid foaming infrastructure device also includes Melt Pump (4), Described drawing-in device (1), double screw extruder (2), foaming agent injected system, single screw extrusion machine (3), Melt Pump (4) It is linked in sequence successively with molding die (5).

Equipment the most according to claim 5, it is characterised in that described Melt Pump (4) is gear type Melt Pump.

Equipment the most according to claim 1, it is characterised in that described drawing-in device (1) and the feeding of (2) on double screw extruder Mouth (6) connects.

Equipment the most according to claim 1, it is characterised in that described foaming agent injected system and the gas injection on double screw extruder (2) Mouth (7) connects.

Equipment the most according to claim 1, it is characterised in that described foaming agent is supercritical CO₂。

Equipment the most according to claim 1, it is characterised in that described foaming agent is supercritical N₂Or supercritical N₂With supercritical CO₂Mixed Compound.