CN110901092A

CN110901092A - Preparation system of material with nano-porous structure

Info

Publication number: CN110901092A
Application number: CN201911260709.4A
Authority: CN
Inventors: 刘爱林
Original assignee: Shanghai Xidian New Material Technology Co Ltd
Current assignee: Shanghai Xidian New Material Technology Co Ltd
Priority date: 2019-09-26
Filing date: 2019-12-10
Publication date: 2020-03-24
Also published as: CN110884151A; CN111037940A; CN111037941A

Abstract

The invention aims to provide a preparation system of a material with a nano porous structure, which comprises the following components: a heating unit for heating the preform containing the solvent to melt the preform and vaporize the solvent while maintaining the form of the preform; a bulking unit to bulk the heated material from the heating unit to a desired porosity; and a shaping unit that cools the expanded material from the expanding unit to obtain a material having a nanoporous structure. The invention can prepare the material with the nanometer porous structure with excellent performance by a simplified process at lower cost.

Description

Preparation system of material with nano-porous structure

Technical Field

The invention belongs to the field of material processing and application, and mainly relates to a preparation system of a material with a nano porous structure.

Background

Nanoporous materials are generally useful as the materialHeat insulating material or filtering material. For example, the existing thermal insulation material is generally a special gel which uses gas to replace the liquid in the gel without changing the network structure or volume of the gel per se, and is the product after the hydrogel or the organic gel is dried. It has the features of nano level porous structure, high porosity, etc. and is one of the known solid materials with low density. Such insulation was first made in the 30's of the 20 th century by professor Kistler. The preparation process is complicated and long, and the preparation method is expensive and fragile, so that the preparation method does not attract attention for a long time. With the rapid development of sol-gel technology since the 70 s of the 20 th century, extensive attention has been paid to the research and development of inorganic heat insulating materials based on silica and synthetic polymer heat insulating materials represented by resorcin/formaldehyde and melamine/formaldehyde polycondensates. The porous structure with a large number of nanometer sizes in the heat-insulating material endows the material with ultrahigh porosity (80-99.8%) and high specific surface area (100-1600 m)²(0.004-0.500 g/cm) and ultralow density³) And the like, so that the material has wide application prospects in various fields such as optics, electricity, acoustics, heat, catalysis and the like.

Mixing organic silicon, ethanol and deionized water under an acidic condition, adding phenolic resin, adding ammonia water, carrying out sealed aging on the obtained phenolic resin-silicon dioxide composite hydrogel, carrying out solvent replacement by adopting ethanol and n-hexane to obtain phenolic resin-silicon dioxide composite gel containing an n-hexane solvent, and drying by using supercritical carbon dioxide to obtain the phenolic resin-silicon dioxide composite heat insulation material; dissolving cellulose in NaOH/urea/water solution to obtain cellulose solution, adding chitosan for blending, adjusting the pH value to be acidic to obtain chitosan-cellulose mixed sol, then mixing the chitosan-cellulose mixed sol with potassium permanganate solution, converting the chitosan in a sol system into chitosan carbon by a hydrothermal method, uniformly loading manganese dioxide in the chitosan carbon-cellulose sol system, and finally obtaining the manganese dioxide-chitosan carbon-cellulose gel urea-formaldehyde resin adhesive additive by freeze drying; according to patent CN106564235B, melamine, formaldehyde and water are placed in a reactor, a catalyst, a buffering agent, a solubilizer and a stabilizer are sequentially added, an emulsifier and a plasticizer are added after the melamine is completely dissolved, the mixture is placed in a closed container for gel aging to obtain gel, then absolute ethyl alcohol and acetone are used for replacement, the replaced gel material is subjected to solvent replacement by absolute ethyl alcohol solution, and finally, the melamine nano gel particles are obtained after drying.

The existing preparation processes are all improved aiming at the preparation process of sol-gel, no innovation is provided on the drying method, the preparation processes are complex, and the related preparation equipment is bulky, so that the cost is high.

Disclosure of Invention

The present invention is directed to provide a system for preparing a material having a nanoporous structure, which can prepare a material having a nanoporous structure with excellent performance at a low cost and in a simplified process.

The system for preparing a material having a nanoporous structure according to the present invention comprises: a heating unit for heating the preform containing the solvent to melt the preform and vaporize the solvent while maintaining the form of the preform; a bulking unit to bulk the heated material from the heating unit to a desired porosity; and a shaping unit that cools the expanded material from the expanding unit to obtain a material having a nanoporous structure.

By adopting the preparation system, the preform is melted and the solvent is gasified, namely, the expansion does not occur, by the heating unit under the state of keeping the shape unchanged. The heated material from the heating unit is then expanded by the expansion unit to increase the volume to the desired porosity, whereby the porosity can be controlled by controlling the expansion process performed in the expansion unit to obtain the desired material. The preparation system has simple structure and strong applicability, can greatly simplify the preparation process of the material with the nano porous structure, and reduces the cost. Compared with the existing freeze drying and supercritical drying preparation process, the preparation method is more convenient, quicker and more economical, and the aperture is adjustable, and the existing methods of supercritical carbon dioxide drying and vacuum freeze drying need to form gel before drying and then dry, but the method does not need the step of forming gel. In addition, the existing porous material preparation process generally adopts means such as high-temperature oil bath for puffing, and the puffing process is uncontrollable, so that the preparation system can control the puffing process and further realize the adjustment of porosity. The preparation system can prepare nano porous materials with the porosity of more than 80 percent, and can be suitable for preparing various materials with nano porous structures, such as heat insulation materials with nano porous structures, filter materials with nano porous structures and the like.

Preferably, a first heated mold and a second heated mold are provided, and the preform is placed between the first mold and the second mold; the heating unit comprises a stage of heating and pressurizing the prefabricated body when the first die and the second die are combined; the puffing unit comprises a stage of gradually moving the first die for a specified distance to a set position in a direction away from the second die so as to gradually puff the heated and pressurized material; and the shaping unit comprises a stage of continuously moving the first die in the direction away from the second die again after staying at the set position for a set time until the upper surface of the puffed material is in a non-contact state.

According to the present invention, it is possible to efficiently heat and pressurize a preform containing a solvent to melt and vaporize the solvent while keeping the shape of the heated material unchanged, when the first mold and the second mold are closed; then the heated and pressurized material gradually starts to be expanded at the stage that the first die gradually moves a specified distance to a set position in the direction away from the second die, and the material can be gradually expanded to increase the volume to reach the required porosity by controlling the expansion process; and then after the material stays at the set position for a set time, the first die is moved in the direction away from the second die again until the cooling and setting are started at the stage that the surface of the expanded material close to the side of the first die is in a non-contact state. The invention can realize the controllability of the puffing process by a simple structure.

Preferably, the device further comprises a closed container arranged between the first die and the second die; the closed container includes: an upper member and a lower member; the lower member includes a bottom portion placed on the second mold and a preform accommodating portion having a groove provided on the bottom portion; the upper member includes a top fixed to the first die to be movable therewith and a projection projecting from the top into the groove; the projection portion is sealingly fittable into and movable in the groove of the preform accommodating portion. The puffing of the present invention requires pressure released by steam to support the puffing, and by using the closed vessel, the steam can be prevented from escaping during the heating of the preform.

Preferably, the device further comprises a die cavity arranged in the first die and/or the second die in an area adjacent to the first die and the second die, and a feeding unit for extruding the prefabricated body into the die cavity.

Preferably, the porosity is controlled by controlling the speed of movement of the first die of the bulking unit. Therefore, the controllability of the puffing process can be conveniently realized according to the requirement.

Drawings

FIG. 1 is a schematic structural diagram of a system for preparing a material having a nanoporous structure according to a first embodiment of the invention;

FIG. 2 is a schematic structural view of a closed vessel in a production system according to a first embodiment of the present invention;

FIG. 3 is a schematic structural diagram of a system for preparing a material having a nanoporous structure according to a second embodiment of the invention;

FIG. 4 shows a schematic control block diagram of a system for preparing the material having a nanoporous structure according to the invention;

FIG. 5 shows a schematic flow chart of the preparation using the preparation system of the material having a nanoporous structure of the invention;

reference numerals:

1. an upper die (first die);

2. a lower die (second die);

3. a closed container;

4. an upper member (first member);

5. a lower member (second member);

6. a top portion;

7. a bottom;

8. a bump portion;

9. a preform accommodating portion;

s, accommodating space;

11. a first die;

12. a second mold;

13. a mold cavity;

14. a feed unit;

15. a feed inlet;

16. a feeding part;

17. an injection port.

Detailed Description

The present invention is further illustrated by the following examples, which are to be understood as merely illustrative and not restrictive.

Disclosed herein is a system for preparing a material having a nanoporous structure according to the present invention, comprising: a heating unit for heating the preform containing the solvent to melt the preform and vaporize the solvent while maintaining the form of the preform; a bulking unit to bulk the heated material from the heating unit to a desired porosity; and a shaping unit that cools the expanded material from the expanding unit to obtain a material having a nanoporous structure.

The above preform may be prepared in advance in a preform preparation unit, and for example, a solvent type resin and a solvent may be used for preparation, but the present invention is not limited thereto, and a water-soluble resin, an inorganic sol, a composite of a resin and an inorganic sol, and the like may be used in addition to a solvent type resin. The preform is allowed to contain a suitable amount of solvent, which can be vaporized at a certain temperature to allow the preform to expand and form a hole.

The heat insulation material with the nano-porous structure and the filtering material with the nano-porous structure can be prepared into preforms by adopting the same raw materials and processes, and different final products with the nano-porous structure based on different thicknesses of the preforms can be respectively used as the heat insulation material or the filtering material. For example, a preform for preparing a thermal insulation material having a nanoporous structure may be directly subjected to a subsequent preparation process using the preparation system of the present invention. And a thin layer can be coated on the carrier of the same prefabricated body, and then the preparation system is adopted to carry out the subsequent preparation process, so that the filtering material with the nano-porous structure is obtained.

The following description will be given by taking a solvent-based resin as an example of the preform, but the production system of the present invention is also applicable to preforms made of other materials.

The solvent type resin can be dissolved by a solvent to obtain a solution in which the solvent is uniformly dispersed in the solvent type resin, and a preform with the solvent type resin as a framework and a proper amount of the solvent uniformly dispersed in the solvent type resin can be obtained. Preferably, an excess of solvent is used to dissolve the starting material to provide sufficient dissolution of the starting material to ensure uniform dispersion of the solvent in the resin starting material to aid in the expansion of the product to provide a more uniform pore size distribution. The resin can be dissolved in a solvent in an amount of 0.2 to 10 times the weight of the resin. The amount of the solvent is different according to the dissolution performance of the resin. And some resin products are liquid, and can be uniformly mixed by adding a small amount of solvent. It is understood that the resin should be completely dissolved in the solvent. The preform preparation unit may be a conventional apparatus for preparing an aerogel preform, and may be mixed using a mixing device such as a mixer, a blender, or the like, so that the solvent is uniformly dispersed in the solvent-type resin. The resin and solvent may also be mixed by mechanical action under heated conditions. Mixing can be achieved using equipment with high temperature capabilities such as internal mixers, high temperature kneaders, twin-cone extruders, twin-screw extruders, twin-roll presses, and the like.

The solvent is used for making holes and can be gasified at a certain temperature to enable the prefabricated body to be expanded and formed with holes. Any solvent may be used as long as it can completely dissolve the resin. Preferably, a preform having a solvent content of 5 to 40wt% in total is prepared. Too high solvent content easily causes too large pore diameter or uneven pore diameter distribution, and too low solvent content easily causes insufficient puffing degree or unsuccessful puffing, so that the control of the solvent content in a certain range is beneficial to the uniform distribution of the pore diameter of the material and the control of the pore diameter size of the material, and the heat preservation and heat insulation performance of the material is improved. Thus, the solvent in the above-mentioned resulting solution can be reduced until the solvent reaches a desired content. The solvent of the resulting solution can be reduced, for example, by heating at a temperature below the glass transition temperature of the solvent-type resin, e.g., 25 to 200 ℃. The heating manner and apparatus are not limited as long as the content of the solvent is reduced to a desired content. The solvent is reduced at a lower heating temperature at a lower speed, but the heating temperature cannot be too high to avoid the resin from being expanded in advance, and if the solvent in the preform is gasified and expanded in advance at a too high heating temperature, the pore diameter and the pore diameter distribution of the product cannot be controlled to be uneven.

The system for preparing the material having a nanoporous structure according to the present invention is described in further detail below. The following examples are described by taking the preparation of the thermal insulation material having a nanoporous structure as an example, but the present invention is not limited thereto, and is also applicable to the preparation of the filter material having a nanoporous structure.

First, the preform containing the solvent (for example, a preform prepared using a solvent-based resin and a solvent) is heated in a heating unit while maintaining the form thereof, and the molten resin solvent is vaporized by melting the molten resin. The heating temperature for heating the preform to vaporize the molten solvent of the resin is preferably higher than the boiling point of the solvent and higher than the glass transition temperature of the solvent-based resin. More preferably, the heating temperature is 100 to 400 ℃. The heating temperature exceeds the boiling point of the solvent and the glass transition temperature of the resin, and is higher than the boiling point of the solvent and the glass transition temperature of the resin by a part, so that the rapid puffing of the resin is facilitated, the puffing time is shortened, and the temperature setting is not too high in consideration of the influence of the temperature on the pore diameter and the pore diameter distribution, the energy loss, the safety and the like. It will be appreciated that during heating (prior to expansion), it is ensured that the resin melts while the solvent vaporizes at this point in time, thereby facilitating the subsequent expansion of the material to form a nanoporous material having a uniform pore size distribution. The heating time can be reduced when the heating temperature is high. The heating means is configured to maintain the form of the resin melt solvent in a state where the resin melt solvent is vaporized without swelling. Preferably, maintaining its form can be achieved by controlling its volume to be constant.

Next, in the expansion unit, the heated material from the heating unit is expanded to increase the volume to achieve the desired porosity. The porosity is related to the degree of puffing, i.e. by controlling the puffing process in the puffing unit, the porosity of the material can be adjusted to achieve a specified level. The expansion may be such that the volume of the material expands in any one, two or three directions of XYZ. The requirements, operation processes, equipment or molds are different. The preparation system can ensure that the porosity of the prepared heat insulation material with the nano-scale aperture is 80-99%. And the volume increasing process of the materials in the puffing process is a gradual change process under a controllable state. In the present invention, expansion can be achieved by expanding the material in a die and by controllably moving the first die and/or the second die.

Preferably, a variable volume closed vessel may be provided between the first and second dies, the volume change of the vessel being controlled to control the expansion process to achieve the desired porosity. The puffing unit can be a die consisting of a first die and a second die of fixed size, and the first die and/or the second die can move relatively in a control manner to realize puffing. Specifically, the pressure relief speed can be controlled by controlling the demolding speed, so that the pressure during puffing is controlled to be slowly reduced, the material is uniformly puffed under the condition of pressure, and the porosity can be controlled. The pressure during puffing is gradually reduced from 20-0 MPa.

The first and second molds may be upper and lower molds moving in a vertical direction, or front and rear molds moving in a horizontal direction.

And finally, cooling the expanded material from the expansion unit in the shaping unit to obtain the heat insulation material with the nano porous structure. The volume of the material is no longer changed in the shaping unit, so that the shape of the material that has been subjected to the expansion process in the preceding expansion unit can be determined. In the shaping unit, for example, natural cooling means can be used.

Specifically, fig. 1 is a schematic structural diagram of a system for preparing a material having a nanoporous structure according to a first embodiment of the present invention.

As shown in fig. 1, in the present embodiment, the first die and the second die may be vertically movable upper and lower dies. I.e. comprising a heated upper die 1 and a lower die 2, with the preform interposed between the upper die 1 and the lower die 2. In the present embodiment, the preform may be in the form of a sheet, but the shape of the preform is not limited thereto, and other shapes may be adopted as necessary. The shapes of the upper die 1 and the lower die 2 may be set as needed, and may be flat plate-like or other shapes.

In the present embodiment, the heating means includes a stage of heating and pressurizing the preform when the upper mold 1 and the lower mold 2 are clamped (as shown in the right drawing of fig. 1). At this time, the preform placed between the upper mold 1 and the lower mold 2 is heated and pressurized, whereby the preform is melted and the resin melt solvent is vaporized, and the volume of the material is maintained. That is, the heated material is kept in a form without being subjected to pressure limitation, and at this time, swelling, that is, foaming does not occur although the solvent is vaporized. Preferably, the heating temperature can be 140-400 ℃, and the pressure value can be 0.01-20 MPa.

The puffing unit includes a step of gradually moving the upper die 1 in a direction away from the lower die 2 by a predetermined distance to a set position to gradually puff the heated and pressurized material (as shown in the left drawing of fig. 1). At this time, as the movement of the upper mold 1 (i.e., the mold release) is started, the pressure is gradually released, and thereby the material interposed between the upper mold 1 and the lower mold 2 gradually starts to swell. In the expansion unit, the material is not heated any more.

Specifically, the present invention includes a heating unit (not shown) for heating the upper mold 1 and the lower mold 2, and the heating unit may be any device capable of heating the upper and lower molds, and may be a device for heating by means such as heat carrier heating, resistance heating, or electric induction heating. The present invention further includes a pressure unit for generating a pressure between the upper and lower dies, for example, a hydraulic system acting on the upper die, and the pressure value output from the hydraulic system may be controlled by controlling the pressure setting unit, for example, by adjusting a pressure valve or the like.

The present invention further includes a driving unit such as a driving motor, a hydraulic cylinder, or an air cylinder, etc. connected to the upper mold 1 to drive the movement of the upper mold 1.

In addition, the invention can also comprise a control unit which is connected with the driving unit, the heating part and the pressure setting unit to control the driving unit, the heating part and the pressure setting unit, thereby realizing the control of the movement of the upper die, the heating temperature and the pressure value. The control unit may be, for example, a programmable controller. The control unit may include a control part that may control the moving state of the upper mold, the heating temperature, and the pressure, and a display part that may display parameters controlled by the control part, such as the moving state of the upper mold, the heating temperature, and the pressure value.

Further, the distance that the upper die 1 moves in the puffing unit is related to the expansion factor of the material, which also determines the porosity of the final product, and how much puffing factor is needed sets the corresponding moving distance. The movement time may be about 0.5s, for example. Therefore, in order to obtain a desired porosity, a desired upper mold moving distance may be set, that is, the set positions may be set at different heights as necessary.

The porosity of the material can be controlled by controlling the speed of movement of the upper die 1 of the expansion unit, i.e. the speed of demoulding. Specifically, the pressure relief speed can be controlled by controlling the demoulding speed so as to control the pressure during puffing, and the pressure during puffing is a process of slowly reducing from 20MPa to 0, so that the material can be uniformly puffed under the condition of pressure, and the porosity can be further controlled. Further, the speed of expansion and the speed of pressure release control the porosity and pore size of the final product.

The shaping unit comprises a stage of continuing to move the upper die 1 in a direction away from the lower die 2 again after staying at the set position P for a predetermined time until the upper surface of the puffed material is in a non-contact state. The non-contact state means that the upper surface of the expanded material is not in contact with other members or members, and in the present embodiment, does not contact with the upper mold 1. For the material which has reached the required swelling degree, the demoulding can be firstly postponed, the material is gradually shaped along with the gradual cooling of the material, the demoulding is continued after a certain time (namely the material stays at the set position P for a set time, the set time is preferably 10s-60 s) is maintained until the upper mould 1 is completely not contacted with the material, and the shaping of the swelled material can be completed through natural cooling.

FIG. 2 is a schematic view showing the structure of a closed vessel which can be used in the production system according to the first embodiment of the present invention. The closed vessel 3 may be interposed between the upper mold 1 and the lower mold 2. As shown in fig. 2, the closed casing 3 includes: an upper member 4 and a lower member 5. The lower member 5 includes a bottom 7 placed on the lower mold 2 and a preform accommodating part 9 having a groove provided on the bottom 7. The upper member 4 includes a top portion 6 fixed to the upper die 1 so as to be movable therewith and a lug portion 8 projecting downward from the top portion 6. The projection 8 can be sealingly inserted into and moved in a groove of the preform receiving portion 9, which between them constitutes a sealed receiving space S of the preform. The closed container can be made of metal with good heat-conducting property. The preform may be placed in the accommodating space S, and the closed container 3 may be heated and pressurized when the upper and lower molds are closed, so that the accommodated preform may be heated and pressurized by the upper and lower members. The upper member 4 is gradually moved in a direction away from the lower member 5 along with the movement of the upper die 1, so that the heated material in the accommodating space S is gradually expanded. Similarly to the above, the material which has reached the desired degree of expansion can be released from the mold temporarily, gradually set as the material is gradually cooled, and continue to be released from the mold after a certain period of time.

Fig. 3 is a schematic structural diagram of a system for preparing a material having a nanoporous structure according to a second embodiment of the invention.

As shown in fig. 3, the present embodiment includes a first mold 11 and a second mold 12 that move in the horizontal direction of heated water. Further, a cavity 13 provided in the first die 11 and/or the second die 12 in an area adjacent between the first die 11 and the second die 12, and a feeding unit 14 for extruding the preform into the cavity 13 are included. The feeding unit 14 may, for example, comprise a feeding opening 15 and a feeding portion 16 connected between the feeding opening 15 and the mold cavity 13. The feeding portion 16 may be formed in a screw-conveying structure to extrude the material into the cavity 13 through the injection port 17 and to stably disperse the material uniformly.

Similarly to the first embodiment, in the present embodiment, the heating means includes a stage of heating and pressurizing the preform when the first mold 11 and the second mold 12 are clamped. The puffing unit comprises a stage of gradually moving the first die 11 in a direction away from the second die 12 by a predetermined distance to a set position to gradually puff the heated and pressurized material. The shaping unit comprises a stage of continuing to move the first die 11 in the direction away from the second die 12 again after staying at the set position for a set time until the surface of the expanded material close to the side of the first die is in a non-contact state. The present embodiment also includes the above-described driving means, heating unit, pressure setting means, and control means. The porosity of the material can also be controlled by controlling the speed of demoulding.

The operation of the system for preparing a material having a nanoporous structure according to the present invention will be described in detail below with a specific example. This example is illustrated by a preform prepared using a solvent-based resin and a solvent, and the process flow is shown in FIG. 5.

Step S1, a preform is prepared.

Step S2, the preform is placed between the upper and lower dies. In this step, the preform may be directly placed between the upper and lower molds, may be placed in a closed container between the upper and lower molds, or may be injected into the mold cavity between the upper and lower molds.

Step S3, heating and pressurizing the preform at the set pressure value and heating temperature, in a specific example, the heating temperature is set to be 400 ℃ by the control unit, preferably 230 ℃ to 300 ℃, and the pressure is 0.01 to 20 MPa. The preform is heated to melt the resin and vaporize the molten solvent, and the preform is kept in a state of a constant shape without being swelled.

And step S4, releasing pressure and stopping heating, so that the upper die is gradually demoulded to a set position to enable the heated material to be expanded. In a specific example, the moving speed of the upper die is set to be 0.4-10 m/min through the control unit, the time is set to be 0.5-4 s, and the distance is determined according to the thickness of the material to be puffed, and generally can be 1-10 mm.

And step S5, after the material stays at the set position for a preset time, demoulding is continued until the upper surface of the puffed material is not contacted with other parts, so that the material is cooled and shaped. Preferably, the material is held under pressure and then slowly depressurized directly until the upper surface of the expanded material is not in contact with other parts, so that the material is cooled and set without holding more than once in the middle.

Finally, in step 6, the final product after sizing is taken out.

As the present invention may be embodied in several forms without departing from the spirit of essential characteristics thereof, the present embodiments are therefore illustrative and not restrictive, since the scope of the invention is defined by the appended claims rather than by the description herein, and all changes that fall within metes and bounds of the claims, or equivalence of such metes and bounds thereof are therefore intended to be embraced by the appended claims.

Claims

1. A system for preparing a material having a nanoporous structure, comprising:

a heating unit for heating the preform containing the solvent to melt the preform and vaporize the solvent while maintaining the form of the preform;

a bulking unit to bulk the heated material from the heating unit to a desired porosity; and

a shaping unit for cooling the expanded material from the expansion unit to obtain the material with nano-porous structure.

2. The production system according to claim 1,

providing a heated first mold and a second mold, the preform being disposed between the first mold and the second mold;

the heating unit comprises a stage of heating and pressurizing the prefabricated body when the first die and the second die are combined;

the puffing unit comprises a stage of gradually moving the first die for a specified distance to a set position in a direction away from the second die so as to gradually puff the heated and pressurized material;

the shaping unit comprises a stage of continuously moving the first die in the direction away from the second die again after staying at the set position for a set time until the surface of the puffed material close to the side of the first die is in a non-contact state.

3. The production system according to claim 2,

the closed container is arranged between the first die and the second die;

the closed container includes: a first member and a second member;

the second member includes a bottom portion placed on the second mold and a preform accommodating portion having a groove provided on the bottom portion;

the first member includes a top fixed to the first die so as to be movable therewith and a projection portion projecting from the top into the groove;

the projection portion is sealingly fittable into and movable in the groove of the preform accommodating portion.

4. The production system according to claim 2,

the device also comprises a die cavity arranged in the first die and/or the second die in an adjacent area between the first die and the second die, and a feeding unit for extruding the prefabricated body into the die cavity.

5. The production system according to any one of claims 1 to 4,

controlling the porosity by controlling a moving speed of the first die of the bulking unit.