A primary foaming device with secondary foaming performance

Abstract

A primary foaming device with secondary foaming performance comprises a reactor, a ball valve is provided at the discharge port of the reactor, the ball valve is connected to one end of a cooling pipe, the other end of the cooling pipe is connected to one end of a drain pipe, the other end of the drain pipe is connected to the discharge pipe, the discharge pipe is coated with a heater, and a plurality of drainage holes are provided on the pipe wall of the drain pipe; a plurality of capillaries are provided in the cooling pipe, the material inlet ends of the plurality of capillaries are connected to the outlet of the ball valve, and the material outlet ends of the plurality of capillaries are connected to the drain pipe; a cooling channel for the flow of coolant is formed between the plurality of capillaries, and the flow direction of the coolant in the cooling channel is opposite to the flow direction of the primary foaming particles in the capillaries; the inlet of the cooling channel is connected to the liquid inlet on the cooling pipe, and the outlet of the cooling channel is connected to the liquid outlet on the cooling pipe. According to the present invention, after the primary foaming, there is no need to pressurize the particles again, so the process can be shortened, the processing time can be saved, and the processing efficiency can be improved.

Description

Technical Field

[0001] The invention belongs to the technical field of EPP foaming, and in particular relates to a primary foaming device with secondary foaming performance. Background Art

[0002] Expanded polypropylene material, referred to as EPP, is a new type of foam material that is both environmentally friendly and lightweight. It has good development and application prospects in the automotive industry, packaging industry, furniture industry and special industries. Especially as the concept of energy conservation and environmental protection continues to penetrate into everyone's daily concepts, the market prospects of foamed polypropylene cannot be underestimated.

[0003] Foamed polypropylene material is a kind of foamed material produced by intermittent process through supercritical carbon dioxide autoclave foaming technology. Its production process is a physical change with good environmental performance. Generally, the material is foamed by autoclave to obtain a primary product with a density of 50g / L, and then through a secondary foaming process to obtain a secondary polypropylene foam material with a lower density, and its minimum density can reach 8-10g / L. In the traditional autoclave foaming process, there is a certain time interval between the primary and secondary foaming. The secondary foaming needs to be pre-pressed again to make the product have the foamability of secondary foaming. The time interval is long and wastes manpower and material resources, and the overall efficiency is low. Summary of the invention

[0004] The purpose of the present invention is to provide a primary foaming device with secondary foaming performance, which can quickly solidify the skin layer of the valve outlet particles by cooling, greatly maintain the internal pressure from being released, and then perform secondary foaming on the primary foamed particles after dewatering by means of a hot pipe, which greatly improves the overall efficiency of foaming and has a good improvement effect on controlling the uniformity of product particles and improving the subsequent product molding quality.

[0005] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a primary foaming device with secondary foaming performance, comprising a reactor, a ball valve is arranged at the discharge port at the bottom of the reactor, the ball valve is connected to one end of a cooling pipe, the other end of the cooling pipe is connected to one end of a drain pipe, the other end of the drain pipe is connected to a discharge pipe, the discharge pipe is coated with a heater, and a plurality of drainage holes are opened on the pipe wall of the drain pipe;

[0006] A plurality of capillaries are arranged in the cooling pipe, the material inlet ends of the plurality of capillaries are connected to the outlet of the ball valve, and the material outlet ends of the plurality of capillaries are connected to the drain pipe; a cooling flow channel for the flow of coolant is formed between the plurality of capillaries, and the flow direction of the coolant in the cooling flow channel is opposite to the flow direction of the primary foamed particles in the capillaries; the inlet of the cooling flow channel is connected to the liquid inlet on the cooling pipe, and the outlet of the cooling flow channel is connected to the liquid outlet on the cooling pipe.

[0007] The diameter of the cooling pipe is 40-50 cm, the diameter of the capillary is 3-5 cm, and the capillary is arranged in multiple layers in the cooling pipe. Each layer of the capillary forms a circle along the circumference, and the multiple layers of the capillary are arranged in concentric circles.

[0008] The capillaries in different layers are arranged along the radial direction of the cooling channel.

[0009] The radial angle between two adjacent capillaries in the radial direction is 22.5°.

[0010] The distance between the center of the outermost capillary tube and the inner wall of the cooling pipe is 1-2 cm, and the distance between the centers of adjacent capillaries is 6-8 cm.

[0011] The diameter of the drainage hole on the drainage pipe is 1-1.5 mm.

[0012] The heater is a steam pipe, and the steam pipe is spirally arranged around the discharge pipe.

[0013] A stirrer is arranged at the bottom of the reactor.

[0014] The beneficial effects of the present invention are as follows: the present invention rapidly solidifies the cortex of the valve exiting particles by cooling, thereby greatly maintaining the internal pressure from being released, and then, through a hot pipe, the primary foamed particles after dewatering are subjected to secondary foaming, which greatly improves the overall efficiency of foaming, and has a good improvement effect in controlling the uniformity of product particles and improving the subsequent product molding quality.

[0015] Therefore, the present invention does not need to pressurize the particles again after the first foaming, thus shortening the process, saving processing time and improving processing efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of the present invention;

[0017] Figure 2 is a cross-sectional view of a cooling pipe of the present invention;

[0018] Markings in the figure: 1, reactor, 2, agitator, 3, ball valve, 4, liquid outlet, 5, cooling pipe, 501, capillary, 502, cooling channel, 6, liquid inlet, 7, drain pipe, 8, heater, 9, discharge pipe. DETAILED DESCRIPTION

[0019] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments, but they are not intended to limit the invention in any way.

[0020] See attached Figure 1 , 2As shown, a primary foaming device with secondary foaming performance includes a reaction kettle 1, an agitator 2, a ball valve 3, a cooling pipe 5, a drain pipe 7, a discharge pipe 9 and a heater 8.

[0021] The reactor 1 is a high-pressure autoclave for primary foaming, which is used for primary foaming of EPP. The agitator 2 is arranged at the bottom of the reactor 1. The stirring blades of the agitator 2 are used to evenly disperse the polypropylene particles and the water medium in the reactor 1 to prevent the polypropylene particles from stratifying with water during heating and foaming. The stirring blades of the agitator are propeller structures. The discharge port at the bottom of the reactor 1 is connected to the inlet of the ball valve 3, and the ball valve 3 is used to control the foaming and sealing of the reactor 1. The outlet of the ball valve 3 is connected to the material inlet side of the cooling pipe 5, and the material outlet side of the cooling pipe 5 is connected to one end of the drain pipe 7, and the other end of the drain pipe 7 is connected to the discharge pipe 9, and the heater 8 is arranged outside the discharge pipe 9.

[0022] Furthermore, a liquid inlet 6 is provided on the material outlet side of the cooling pipe 5 for introducing coolant, and a liquid outlet 4 is provided on the material inlet side of the cooling pipe 5 for discharging coolant. After the coolant is cooled outside the cooling pipe 5 and drops to 70-90°C, it enters the cooling pipe 5 again through the liquid inlet 6 to ensure that the temperature of the coolant in the cooling pipe 5 is relatively constant.

[0023] Specifically, the coolant is cooling water, cooling oil or a mixture of water and ethylene glycol.

[0024] like Figure 2 As shown, a plurality of capillaries 501 are arranged inside the cooling pipe 5, the material inlet end of the capillary 501 is connected to the outlet of the ball valve 3, and the material outlet end of the capillary 501 is connected to the drain pipe 7. The primary foaming particles generated by primary foaming in the reactor 1 flow into the cooling pipe 5 through the capillary 501 along with the water in the reactor 1. A cooling channel 502 for the flow of coolant is formed between the plurality of capillaries 501, the inlet of the cooling channel is connected to the liquid inlet 6, and the outlet of the cooling channel is connected to the liquid outlet 4. The coolant flows in the cooling channel 502 in the reverse direction to the primary foaming particles in the capillary 501, and the primary foaming particles are quickly cooled down to promote the growth of the cortex of the primary foaming particles.

[0025] The wall of the drain pipe 7 is provided with a plurality of drain holes, the size of which is smaller than the particle size of the primary foaming product, for draining the water flowing out of the reactor 1 and releasing the pressure of the reactor 1 to prevent subsequent pipelines from being damaged by pressure. Preferably, the diameter of the drain hole is 1-1.5 mm.

[0026] The heater outside the discharge pipe 9 is a steam pipe, which is spirally arranged around the discharge pipe and covers the discharge pipe 9. The steam at 120°C flows into the steam pipe in a direction opposite to the flow direction of the material in the discharge pipe. After the primary foamed particles are drained through the drain pipe 7, they are continuously heated when they enter the discharge pipe 9 heated by steam, which promotes the growth of the particle size again, realizes secondary foaming, and finally obtains secondary foamed particles.

[0027] For example Figure 2 As shown, the diameter of the cooling pipe 5 is φ1=40-50cm, the diameter of the capillary 501 is φ2=3-5cm, the capillary 501 is arranged in multiple layers in the cooling pipe 5, each layer of the capillary 501 is arranged in a circle along the circumferential direction, the multiple layers of the capillary 501 are arranged in concentric circles, the capillaries 501 of different layers are arranged along the radial direction of the cooling pipe 5, and the radial angle β of the capillaries 501 in two adjacent radial directions is 22.5°. The distance L1 between the center of the outermost capillary 501 and the inner wall of the cooling pipe is 1-2cm, and the center distance L2 of the capillaries of adjacent layers is 6-8cm.

[0028] The foaming process of EPP using the present invention is as follows: first, polypropylene particles and water medium are heated in a reactor 1 and foamed once; then, a coolant at 70-90° C. is continuously introduced into the cooling pipe 5, and the ball valve 3 is opened during the circulation of the coolant, and the primary foamed particles in the reactor 1 enter the capillary 501 along with the water, and the particle skin is quickly solidified under the cooling effect of the coolant in the cooling channel 502; then, the primary foamed particles with solidified skin flow into the drain pipe 7 along with the water, the water therein is discharged, and the primary foamed particles enter the heated discharge pipe 9 to achieve secondary foaming and obtain secondary foamed particles.

[0029] The above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Those skilled in the art should understand that the specific implementation modes of the present invention may be modified or replaced by equivalents with reference to the above embodiments. Any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention are within the scope of protection of the pending claims.

Claims

1. A primary foaming device with secondary foaming performance, comprising a reactor, wherein a ball valve is provided at the discharge port at the bottom of the reactor, characterized in that: The ball valve is connected to one end of the cooling pipe, the other end of the cooling pipe is connected to one end of the drain pipe, the other end of the drain pipe is connected to the discharge pipe, the discharge pipe is covered with a heater, and a plurality of drainage holes are opened on the wall of the drain pipe; A plurality of capillaries are arranged in the cooling pipe, the material inlet ends of the plurality of capillaries are connected to the outlet of the ball valve, and the material outlet ends of the plurality of capillaries are connected to the drain pipe; a cooling flow channel for the flow of coolant is formed between the plurality of capillaries, and the flow direction of the coolant in the cooling flow channel is opposite to the flow direction of the primary foamed particles in the capillaries; the inlet of the cooling flow channel is connected to the liquid inlet on the cooling pipe, and the outlet of the cooling flow channel is connected to the liquid outlet on the cooling pipe.

2. The primary foaming device with secondary foaming performance according to claim 1, characterized in that: The diameter of the cooling pipe is 40-50 cm, the diameter of the capillary is 3-5 cm, and the capillary is arranged in multiple layers in the cooling pipe. Each layer of the capillary forms a circle along the circumference, and the multiple layers of the capillary are arranged in concentric circles.

3. The primary foaming device with secondary foaming performance according to claim 2, characterized in that: The capillaries in different layers are arranged along the radial direction of the cooling channel.

4. The primary foaming device with secondary foaming performance according to claim 3, characterized in that: The radial angle between two adjacent capillaries in the radial direction is 22.5°.

5. The primary foaming device with secondary foaming performance according to claim 3, characterized in that: The distance between the center of the outermost capillary tube and the inner wall of the cooling pipe is 1-2 cm, and the distance between the centers of adjacent capillaries is 6-8 cm.

6. The primary foaming device with secondary foaming performance according to claim 1, characterized in that: The diameter of the drainage hole on the drainage pipe is 1-1.5 mm.

7. The primary foaming device with secondary foaming performance according to claim 1, characterized in that: The heater is a steam pipe, and the steam pipe is spirally arranged around the discharge pipe.

8. The primary foaming device with secondary foaming performance according to claim 1, characterized in that: A stirrer is arranged at the bottom of the reactor.

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