CN208118254U - A kind of macromolecule polymer material supercritical fluid foam device - Google Patents

Abstract

The utility model discloses a supercritical fluid foaming device of polymer material, which comprises a mould, a gas cylinder, a booster pump, a first air valve, a second air valve, a third air valve and a radio frequency power supply. Cavity, the mold is provided with an air inlet and an exhaust hole connected to the mold cavity, the gas cylinder, the first air valve, the booster pump, the second air valve and the air inlet of the mold are connected in sequence, and the third air valve is connected to the on the vent hole of the mold. Compared with the prior art, the utility model has uniform heating and fast heating speed, and can realize rapid, efficient and uniform foaming of high molecular polymer materials.

Description

A supercritical fluid foaming device for polymer materials

technical field

The utility model relates to the technical field of polymer foaming equipment, in particular to a high molecular polymer material supercritical fluid foaming device.

Background technique

Polymer foaming materials are widely used in heat insulation, sound insulation, shock absorption, shoemaking and other fields. At present, the commonly used foaming methods of polymer materials include physical foaming and chemical foaming. The chemical foaming method refers to that after the chemical foaming agent is blended with the polymer material, at a certain temperature, the chemical foaming agent is heated and decomposed, and the gas generated is the foaming of the polymer material. At present, the heating method is mainly electric heating. High consumption, low efficiency and other problems, while the chemical blowing agent has heavy odor, is not environmentally friendly, has certain toxic and side effects and other problems. Physical foaming usually refers to supercritical fluid foaming technology. Since the gas used in physical foaming is usually carbon dioxide or nitrogen, it is very environmentally friendly.

In recent years, physical foaming technology has become an emerging technology in the field of polymer material foaming. At present, there are three main ways of polymer physical foaming. The first is extrusion foaming, that is, the polymer dissolved in supercritical fluid is extruded from a single-screw or twin-screw extruder, and is qualitatively shaped into a sheet or plate through a die. This method can obtain high foaming material, but the foam material has a single shape and can only be a sheet or rod material; the second is to extrude the polymer dissolved in the supercritical fluid into the mold, and the polymer foams in the mold. This method can Foaming materials with special shapes can be obtained, but only materials with small expansion ratios can be obtained; the third method is autoclave foaming, that is, putting the material into an autoclave, ventilating to apply pressure, and then heating with electricity or oil to The heat is transferred from the outside to the inside of the polymer material in the autoclave, and the foamed material is usually foamed particles, such as the E-TPU material of Bavs. These foamed particles need to be hot-pressed. This method can Expanded particles with a high expansion ratio can be obtained, but foamed materials with special shapes cannot be obtained, and both electric heating and oil heating have the problem of high energy consumption. In addition, in the first method and the second method, the equipment required is complicated and expensive. The traditional physical foaming technology involves electric heating or oil heating. Since the electric heating process heats the polymer material through heat conduction, there are problems such as long heating time, excessive local heating temperature and dead heating in some areas.

In view of this, the inventor of this case conducted in-depth research on the above-mentioned problem, and then this case was produced.

Utility model content

The purpose of the utility model is to provide a high-molecular polymer material supercritical fluid foaming device with uniform heating, fast heating speed and high efficiency.

In order to achieve the above object, the solution of the present utility model is:

A high molecular polymer material supercritical fluid foaming device, including a mold, a gas cylinder, a booster pump, a second air valve and a third air valve, the mold has a mold cavity, and the mold is provided with a communication device The air inlet and exhaust hole of the mold cavity, the gas bottle, the booster pump, the second air valve and the air inlet of the mold are connected in sequence, and the third air valve is connected to the On the exhaust hole of the mold, it is characterized in that: a first air valve is also installed between the gas cylinder and the booster pump, the mold includes an upper mold and a lower mold, and the upper mold and the lower mold There is an insulating gasket used for sealing when the mold is closed. The upper mold, the lower mold and the insulating gasket form the airtight mold cavity after the mold is closed. The upper mold and the lower mold The outer surface of the insulating layer is provided with an insulating layer, and the outer surface of the insulating layer is covered with a metal shell; the air inlet is located on the upper mold or the lower mold, and runs through the insulating layer and the metal shell , the exhaust hole is located on the lower mold or the upper mold, and runs through the insulating layer and the metal shell; it also includes a radio frequency power supply, and the upper mold and the lower mold are both conductive metal or Conductive non-metal, the two poles of the radio frequency power supply are respectively connected to the upper mold and the lower mold through cables.

Preferably, both the upper mold and the lower mold are mold steel.

Preferably, the cable is a cable with the function of shielding battery waves.

Preferably, a layer of Teflon for improving the anti-adhesion performance of the mold cavity is coated on the inner wall of the mold cavity.

By adopting the above-mentioned technical scheme, the beneficial effects of the utility model are as follows: 1. Solve technical problems such as uneven heating in the traditional supercritical foaming process; realize in-mold supercritical foaming; realize supercritical foaming and the ingenuity of radio frequency heating technology combined. 2. The utility model overcomes the defects of the traditional technology, enables the microwave to be generated in the mold cavity, solves technical problems such as uneven heating during the electric heating process in the traditional chemical foaming, improves the heating speed, and realizes fast and efficient foaming. 3. In the utility model, the mold is conductive metal or conductive non-metal. When the radio frequency power is turned on, the mold can directly emit high-frequency radio frequency, and the physical property of penetrating radio frequency is not required on the mold, which is beneficial to reduce the requirements of the mold. 4. In the utility model, the outer surface of the mold is wrapped with an insulating layer, and the outer surface of the insulating layer is covered with a metal shell. The insulating layer can play a role of heat preservation, reduce heat loss, and can also block radio frequency leakage. Function, the metal shell plays the role of shielding radio frequency to avoid leakage. In this way, one layer of blocking radio frequency and one layer of shielding radio frequency can effectively prevent radio frequency leakage, which is safer and ensures safe production. When workers adopt the technical scheme of the utility model to foam the polymer material, they can avoid the radiation of radio frequency. Fifth, the utility model can also be widely used in the foaming of PU, TPU, EVA, PE, PP, SEBS and other elastomeric materials or blended materials. Even for polymer materials that do not absorb radio frequency or have weak polarity, high polar polymer materials or inorganic materials can be blended to act as radio frequency absorbers to achieve radio frequency heating. Therefore, the utility model has broad application prospects and important application value.

Description of drawings

For ease of description, the utility model is described in detail by the following specific embodiments and accompanying drawings.

Fig. 1 is the structural representation of the utility model.

Fig. 2 is the cross-sectional view of the TPU foam material obtained by applying the technical solution of the utility model (the cell morphology figure of the TPU foam material obtained by applying the technical solution of the utility model).

In the picture:

1-Cylinder; 2-Boost pump;

3 - mold cavity;

31-air intake hole; 32-exhaust hole;

51-the first air valve;

52-the second air valve; 53-the third air valve;

61-upper mold; 62-lower mold;

7- insulating spacer; 8- insulating layer;

9-Metal shell; 10-RF power supply;

11 - Cable.

Detailed ways

In order to further explain the technical solution of the utility model, the utility model is described in detail through specific examples below.

Radio frequency is the abbreviation of high-frequency alternating electromagnetic waves, and the frequency range is from 300KHz to 30GHz. Among them, the microwave frequency band (300MHz-300GHz) is a higher frequency band of radio frequency. Traditional radio frequency heating mainly uses high-frequency microwaves to act on objects to achieve the purpose of heating. It has the characteristics of fast heating speed and uniform heating. This heating method is mainly used in food heating lamps, such as household microwave ovens.

As shown in Fig. 1-2, the high molecular polymer material supercritical fluid foaming device of the present utility model comprises a mould, a gas cylinder 1, a booster pump 2, a first air valve 51, a second air valve 52 and a third air valve. Air valve 53, mold cavity 3 is provided on the mold, air inlet 31 and exhaust hole 32 communicating with mold cavity 3 are provided on the mold, gas cylinder 1, first air valve 51, booster pump 2, second air valve 52 It is connected with the air inlet 31 of the mould, and the third air valve 53 is connected to the air vent 32 of the mould. The mold includes an upper mold 61 and a lower mold 62, and a mold for clamping is provided between the upper mold 61 and the lower mold 62. The insulating spacer 7 that acts as a seal, the upper mold 61, the lower mold 62 and the insulating spacer 7 form the airtight above-mentioned mold cavity 3 after mold closing, and the outer surfaces of the upper mold 61 and the lower mold 62 are all provided with an insulating layer 8, The outer surface of the insulating layer 8 is covered with a metal shell 9; the air inlet 31 is located on the upper mold 61, and runs through the corresponding positions of the insulating layer 8 and the metal shell 9, and the exhaust hole 32 is located on the lower mold 62, and runs through the insulating layer. Corresponding positions of layer 8 and metal shell 9; also include radio frequency power supply 10, upper mold 61 and lower mold 62 are conductive metal or conductive non-metal, and the two poles of radio frequency power supply 10 connect with upper mold 61 and lower mold respectively through cable 11 62 connections.

Among the above, specifically: the gas cylinder 1, the first air valve 51, the booster pump 2 and the second air valve 52 are connected in sequence through the connecting pipe, and the second air valve 52 is connected to the air intake of the mold through the connecting pipe or the pipe body connector. The hole 31 is connected, and the third air valve 53 is connected with the exhaust hole 31 of the mold through a connecting pipe or a pipe connector. The connecting pipe and the pipe connector here are all conventional pipe bodies and pipe connectors in the art.

As a preference, both the upper die 61 and the lower die 62 are die steel.

Preferably, the cable 11 is a cable with the function of shielding battery waves. The cable 11 here is a known type of cable, that is, it refers to a cable whose surface is wrapped with a layer of metal mesh to play the role of electromagnetic shielding.

Preferably, the inner wall of the mold cavity 3 is coated with a layer of Teflon for improving the anti-adhesion performance of the mold cavity.

In the above, the air intake hole 31 and the exhaust hole 32 have the same function no matter they are arranged on the upper mold 61 or the lower mold 62, which does not affect the integrity and implementability of the technical solution of the present utility model. The arrangement of the air inlet 31 and the air outlet 32 of the utility model is only a preferred method, and the air inlet 31 and the air outlet 32 are arbitrarily arranged on the upper mold 61 or the lower mold 62, and the same effect can be achieved.

It should be noted that: the role of the metal shell 9 on the upper mold 61 and the lower mold 62 is to shield radio frequency to avoid leakage of radio frequency, so as to ensure that the user will not be radiated by radio frequency when using the device of the present utility model, which is safer. The structure of the high molecular polymer material supercritical fluid foaming device of the utility model is relatively simple and easy to manufacture and install.

The function of the insulating layer 8 is to separate the metal shell 9 from the upper mold 61 and the lower mold 62 to realize electrical non-conduction. The function of the insulating spacer 7 is to cut off the upper mold 61 and the lower mold 62, separate the upper mold 61 and the lower mold 62, and make the two electrically non-conductive, so that when the upper mold 61 and the lower mold 62 are connected to the radio frequency power supply 10 Finally, the upper mold 61 and the lower mold 62 generate a high-frequency oscillating current, and the high-frequency oscillating circuit generates a high-frequency oscillating electric field, thereby generating radio frequency in the entire mold cavity 3 . The radio frequency is continuously reflected back and forth in the mold cavity 3, so that the polymer material in the entire mold cavity 3 is heated evenly.

The function of the booster pump 2 is to raise the gas pressure above the pressure required to reach the supercritical state. This can ensure that the compressed gas injected into the mold cavity 3 is in a supercritical state, which is easy to dissolve into the polymer material heated by radio frequency, and is beneficial to the full foaming and molding of the polymer material.

It is known that molds are needed in the foaming process of polymer molding. The existing technology is to put the mold together with the polymer material in the mold into a closed microwave radiation space to heat the polymer material, which is similar to the common microwave oven heating food in life. However, using this method for foaming, polymer foaming has special requirements for molds. It must be a material that can penetrate microwaves before it can be used as a mold. For example, metal materials cannot be used as molds, which limits radio frequency heating. For the application of many polymer foam products, the mold is required to have sufficient pressure resistance, temperature resistance and other properties during the foaming process. The upper mold 61 and the lower mold 62 of the present invention are not only used as molds for polymer foam molding, but also as positive and negative electrodes for generating radio frequency, which can completely overcome the above problems. In addition, the mold used in the utility model is conductive metal or conductive non-metal, which also solves the problem that the mold material has special requirements.

The utility model is a polymer material supercritical fluid foaming device and foaming method can be widely used in PU, TPU, EVA, PE, PP, SEBS (SEBS thermoplastic elastomer) and other elastomer materials or blending foaming of the material. Even for polymer materials that do not absorb radio frequency or have weak polarity, high polar polymer materials or inorganic materials can be blended to act as radio frequency absorbers to achieve radio frequency heating.

SEBS is saturated SBS, or hydrogenated SBS, which is obtained by hydrogenating special linear SBS to saturate the double bond. SBS is moderately directional hydrogenated in the presence of a catalyst, and the polybutadiene segment is hydrogenated into polyethylene ( E) and polybutene (B) chain drum, so it is called SEBS. Similarly, after the hydrogenation of SIS, the polyisoprene in it is transformed into polyethylene (E) and polypropylene segments, and then saturated SIS (SEPS) is obtained.

The utility model is a supercritical fluid foaming method of high molecular polymer material, which uses TPU polymer material as the raw material and carbon dioxide gas as the physical foaming agent as an example. The specific operation steps are as follows:

(1) Blowing and mold closing: first close the first air valve 51, the second air valve 52 and the third air valve 53, then place the TPU polymer material to be foamed in the mold cavity 3 of the mold, and then close the mold. mold, and then compress the mold after clamping through the existing common pressing mechanism.

In step (1), before the TPU polymer material to be foamed is placed in the mold cavity 3 of the mould, the inner wall of the mold cavity 3 is coated with a layer of Teflon for improving the anti-adhesion performance of the mold cavity 3 dragon. The common pressing mechanism is a conventional foaming vulcanizer, and the mold after clamping is pressed in a conventional way. The Teflon material is effective for a long time after coating and is used as the inner wall of the mold cavity. Therefore, the number of times the inner wall of the mold cavity 3 is coated with Teflon is based on actual production, and does not need to be repeatedly painted. Therefore, adopting the method of the utility model only needs to brush Teflon once, and when using the method of the utility model to carry out foaming such as the second time, the third time, and the Nth time, there is no need to brush Teflon once again.

Among them, Teflon is polytetrafluoroethylene (Polytetrafluoroethylene), the English abbreviation is PTFE, (commonly known as "Plastic King, Hara"). In China, due to the pronunciation, the trademark "Teflon" is also called "Teflon". "Teflon", "Teflon", "Teflon", "Teflon", "Teflon" and so on are all transliterations of "Teflon". The products of this material are generally referred to as "non-stick coating", which is a synthetic polymer material that uses fluorine to replace all hydrogen atoms in polyethylene. This material is resistant to acid and alkali, and various organic solvents, and is almost insoluble in all solvents. At the same time, PTFE has the characteristics of high temperature resistance, and its friction coefficient is extremely low, so it can be used for lubrication, and it has also become an ideal coating for the inner layer of non-stick pans and water pipes.

(2) filling physical foaming agent: start the booster pump 2, open the first gas valve 51 and send the carbon dioxide gas in the cylinder 1 into the booster pump 2, and the booster pump 2 compresses the carbon dioxide gas to 15MPa. The booster pump 2 compresses the carbon dioxide gas into a supercritical fluid, and then opens the second gas valve 52, and the supercritical fluid is automatically injected into the mold cavity 3 of the mould.

In step (2), the booster pump 2 compresses the carbon dioxide gas to form a supercritical fluid above the critical pressure (the critical pressure of the carbon dioxide gas is 7.39 MPa). This can ensure that the compressed carbon dioxide gas injected into the mold cavity 3 is in a supercritical state, which is convenient to dissolve into the TPU polymer material after radio frequency heating, and is conducive to the full foaming and molding of the TPU polymer material. What needs to be explained here is that supercritical fluid is a special state similar to fluid. The minimum pressure at which each gas obtains a supercritical flow state is called the critical pressure. The critical pressure of carbon dioxide is 7.39MPa, and the critical pressure of nitrogen is 3.4MPa.

(3) Heating treatment: turn on the radio frequency power supply 10, the mold generates high frequency radio frequency, the TPU polymer material in the mold cavity 3 is heated under the action of the high frequency radio frequency generated by the mold, and the supercritical fluid dissolves and enters the interior of the TPU polymer material.

In step (3), a high-frequency oscillating electric field is generated between the upper mold 611 and the lower mold 622. TPU is a highly polar polymer material, and the molecules will continuously change directions under the high-frequency oscillating electric field. As the polar molecules continue to turn, they collide with each other and rub against each other to generate heat, which increases the temperature of the TPU polymer material itself. After the TPU polymer material is heated to the required temperature, the RF power supply 108 is turned off. It should be noted that the temperature is set by factors such as the properties of the polymer material and the foaming rate of the desired product. Generally, the higher the temperature in a certain temperature range, the higher the foaming rate, because the higher the temperature of the polymer material, the more supercritical fluid dissolved in the polymer.

(4) Pressure-reducing foaming: first close the second air valve 52, then open the third air valve 53, the air pressure in the mold cavity 3 drops rapidly, and the supercritical fluid dissolved in the TPU polymer material expands rapidly, and the TPU polymer material Foam and fill the entire mold cavity 3.

(5) Open the mold and take the parts, close the first air valve 51 and the booster pump 2, and then open the existing common compression mechanism that compresses the mold after the mold clamping in step (1), and wait for the existing common compression mechanism to be compressed. After the mechanism is fully opened, the mold is opened again, and the foaming material of the TPU polymer is taken out to obtain the foaming material of the TPU polymer having the same shape as the mold cavity 3 .

It should also be noted that, in addition to carbon dioxide gas as a physical blowing agent, nitrogen gas can also be used as a physical blowing agent. Therefore, not only carbon dioxide gas is used as a physical blowing agent, but gases such as nitrogen can also be used as supercritical fluids.

The high molecular polymer material supercritical fluid foaming device and foaming method of the utility model are suitable for physical foaming, and the high molecular polymer is also foamed by physical foaming. Physical foaming usually refers to supercritical fluid foaming technology, that is, the supercritical fluid and materials are placed in a closed space. After heating to a certain temperature, the supercritical fluid penetrates into the polymer material, unloads the pressure instantly, and penetrates into the polymer material. The supercritical fluid in the polymer expands inside the polymer material to obtain a foamed material. Since the gas used for physical foaming is usually carbon dioxide or nitrogen, it is very environmentally friendly.

Therefore, a high molecular polymer material supercritical fluid foaming device and foaming method of the utility model both have broad application prospects and important application values.

The above-mentioned embodiments and drawings do not limit the product form and style of the present utility model, and any appropriate changes or modifications made by those skilled in the art should be considered as not departing from the patent scope of the present utility model.

Claims (4)

1. a kind of macromolecule polymer material supercritical fluid foam device, including mold, gas cylinder, booster, the second air valve and Third air valve has die cavity on the mold, is provided with the air inlet and gas vent for being connected to the die cavity on the mold, described Gas cylinder, the booster, second air valve and the mold air inlet be sequentially connected, the third air valve is connected to described On the gas vent of mold, it is characterised in that：The first air valve, the mold packet are also equipped between the gas cylinder and the booster Upper die and lower die are included, the insulation spacer to seal when being provided between the upper mold and the lower die for molding is described Closed above-mentioned die cavity, the appearance of the upper mold and the lower die are constituted after upper mold, the lower die and insulation spacer molding Face is provided with insulating layer, and the outer surface of the insulating layer is coated with metal shell；The air inlet is located at the upper mold or institute It states in lower die, and runs through the insulating layer and the metal shell, the gas vent is located in the lower die or the upper mold, And run through the insulating layer and the metal shell；It further include having radio-frequency power supply, the upper mold and the lower die are conduction The two poles of the earth of metal or conductive non-metals, the radio-frequency power supply are connect with the upper mold and the lower die respectively through cable.

2. a kind of macromolecule polymer material supercritical fluid foam device according to claim 1, it is characterised in that：Institute Stating upper mold and the lower die is mould steel.

3. a kind of macromolecule polymer material supercritical fluid foam device according to claim 1, it is characterised in that：Institute Stating cable is the cable with shielding battery wave energy.

4. a kind of macromolecule polymer material supercritical fluid foam device according to claim 1, it is characterised in that：Institute It states and coats one layer on the inner wall of die cavity for improving the Teflon of the die cavity anti-adhesive properties.