WO2017171371A1

WO2017171371A1 - Porous structure and preparation method thereof

Info

Publication number: WO2017171371A1
Application number: PCT/KR2017/003358
Authority: WO
Inventors: 이원민; 이병섭; 구양서
Original assignee: 주식회사 지엘켐
Priority date: 2016-03-28
Filing date: 2017-03-28
Publication date: 2017-10-05
Also published as: KR101756862B1

Abstract

The present invention relates to a porous structure and a preparation method thereof. The porous structure is prepared by mixing a porous structure, a microcapsule foaming agent, and a binder and heating them to allow foaming. Prepared by mixing a porous structure, such as silica-based aerogel, with a microcapsule foaming agent and a binder, the porous structure of the present invention is prevented from being blown like powder as well as having typicality. Hence, the porous structure can be formed into specific steric shapes, thus finding applications in various fields including heat insulation materials.

Description

Porous Structure and Manufacturing Method Thereof

The present invention relates to a porous structure and a method for manufacturing the same, and more particularly, to a porous structure prepared by mixing the pore structure and the microcapsule blowing agent.

Structures having a pore structure are high-tech materials with high porosity and very low density with a specific surface area of several hundred m2 / g. The pore structure has excellent thermal insulation, high specific surface area, high porosity and light weight, so it can be used as a heat shield, molecular filter, semiconductor gas sensor and aerospace material.

Among the structures having a pore structure, the airgel is a high-tech material having a porosity of 90% or more, a specific surface area of several hundred m2 / g, a low density, and low thermal conductivity. In addition, the airgel has a lot of pores distributed between the materials, due to the influence of the pores distributed in the material has a very low refractive index and low dielectric constant. Therefore, the porous airgel can be applied in various fields such as dielectric, catalyst, catalyst carrier, heat insulating material, electrode material and soundproof material.

In particular, silica airgel is a material having a three-dimensional network structure, in particular, because it has a low thermal conductivity, it is a material that can be used as a heat insulating material for buildings, refrigerators, automobiles, aircraft, cargo holds and the like.

However, silica airgel is not good mechanical properties due to high porosity, in particular, silica airgel has a very low density and has a form of an unstructured powder has a problem of poor workability. Accordingly, there are various limitations in using silica airgel as a heat insulating material, and its use is difficult to expand.

In order to solve this problem, it is also possible to manufacture and use aerogel blanket by dipping aerogel into nonwoven fabric or glass fiber, but this also has a problem that the aerogel powder is blown, and thus additional construction such as covering the finishing material after construction This is a necessary inconvenience.

Alternatively, the silica aerogel can be imparted with the form by filling the structure, plastic bag, etc., but this method has the disadvantage that the cutting of the structure is impossible.

In addition, the method of filling an airgel into a structure such as an airgel blanket structure or a nonwoven fabric should have a high content of silica airgel per volume in order to realize low thermal conductivity, which has a disadvantage of having a high material cost per unit volume. have.

The present invention is to solve the problems of the prior art as described above, an object of the present invention is to provide a structure having a high porosity while imparting the formability by applying a microcapsule blowing agent and a binder to the airgel.

According to a feature of the present invention for achieving the object as described above, the present invention is prepared by foaming through heating after mixing the pore structure, the microcapsule blowing agent and the binder.

The pore structure is any one of silica-based nanoporous material, silica airgel, alumina-based pore material, titania-based pore material, zirconia-based pore material or carbon-based pore material, or a mixture thereof.

The diameter of the microcapsule blowing agent is 10 ~ 60㎛, the heating includes a primary heating and secondary heating, the primary heating is 80 ~ 150 ℃, the secondary heating is made at 130 ~ 200 ℃.

The binder is ethylene vinyl acetate (EVA), polyvinyl alcohol (PVA), acryl (acryl), acrylamide (acrylamide), vinyl chloride (PVC), polyvinyl acetal, acrylic, It is any one of saturated polyester type, polyamide type, polyethylene type, natural rubber type, synthetic rubber type, silicone type, or melamine type, or a mixture thereof.

According to another feature of the present invention, the present invention provides a method for producing a porous structure to form a mixture by adding a binder to the pore structure and the microcapsule blowing agent, and a drying step of heating the mixture to remove the moisture and solvent of the binder And re-heating the mixture to a relatively high temperature to foam the microcapsule blowing agent.

In the drying step, the mixture is heated at 80 ° C to 150 ° C, and in the foaming step, the mixture is heated at 130 ° C to 200 ° C.

Following the foaming step may further include a cutting step for cutting the prepared porous structure in a predetermined form.

The mixture is dried and foamed in a container having a constant shape.

The porous structure according to the present invention as described above and the method of manufacturing the same have the following effects.

The porous structure of the present invention is prepared by mixing a microcapsule blowing agent and a binder in a pore structure such as a silica-based airgel, so that the powder is prevented from flying and has crystallization. Accordingly, the porous structure can be manufactured in a specific three-dimensional shape has the advantage that can be utilized for various uses, such as insulation.

In addition, the porous structure of the present invention has a very high porosity because the pores of the pore structure and the foamed pores of the microcapsule blowing agent are added. Accordingly, the porous structure of the present invention has a low thermal conductivity, and when used as a heat insulating material, the heat insulating property is greatly improved.

In addition, the porous structure of the present invention includes a microcapsule blowing agent as well as a pore structure such as a silica airgel, so that the foamed pores increase the overall porosity, the specific gravity of the relatively expensive pore structure can be relatively low. Accordingly, the manufacturing cost for manufacturing the porous structure is lowered, thereby improving the economic efficiency.

1 is a photograph showing an embodiment of a porous structure according to the present invention.

Figure 2 is a photograph of the cross-sectional view of one embodiment of the porous structure according to the present invention under a microscope.

Figure 3 is a flow chart showing sequentially one embodiment of a method for producing a porous structure according to the present invention.

Hereinafter, some embodiments of the present invention will be described in detail through exemplary drawings. In adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are assigned to the same components as much as possible even though they are shown in different drawings. In addition, in describing an embodiment of the present invention, if it is determined that the detailed description of the related known configuration or function is to interfere with the understanding of the embodiment of the present invention, the detailed description thereof will be omitted.

In addition, in explaining the component of the Example of this invention, terms, such as 1st, 2nd, A, B, (a), (b), can be used. These terms are only for distinguishing the components from other components, and the nature, order or order of the components are not limited by the terms. If a component is described as being "connected", "coupled", or "mixed" to another component, that component may be directly connected or mixed with that other component, but there is another component between each component. It will be understood that may be "connected", "coupled" or "mixed".

Porous structure according to the present invention is a three-dimensional structure processed by mixing a pore structure, a microcapsule foaming agent and a binder, as shown in Figure 1 after being manufactured in a specific form and cut for various uses, such as insulation, cold protection goods or shoes It can be used for a variety of purposes, such as soles. Among them, the heat insulating material may have a very wide application, such as home appliances such as aircraft, space suits, refrigerators, as well as heat insulating material of the building. In particular, since the porous structure according to the present invention is very easy to process the shape, it can be used in various places by cutting to the desired thickness and size.

The pore structure constituting the porous structure according to the present invention is a structure containing micropores, in this embodiment is a silica airgel. The pore structure may be various examples including fine pores, for example, silica airgel, as well as any one of silica-based nanoporous material, alumina-based pore material, titania-based pore material, zirconia-based pore material or carbon-based pore material It may be a mixture of these. That is, the pore structure may be selected from various pore materials containing the micropores developed in the past.

In the present invention, a microcapsule blowing agent is added to the pore structure. The microcapsule foaming agent is foamed through heating to form pores, and is a thermally expandable microcapsule. The microcapsule foaming agent has a property of rapidly expanding (expanding) at high temperatures, through which the particles increase in volume and have low specific gravity. In addition, the microcapsule foaming agent is a fine and uniform independent bubble is formed, it is possible to expand even in a mixed state with the binder. As an example of the structure of the microcapsule blowing agent, it may be a structure surrounding the outside of the hydrocarbon with an acrylic thermoplastic resin. Accordingly, the outer resin is softened by heating, and the vapor pressure of the foaming agent is increased to expand the outer resin, and when the heating is stopped, the outer resin is cured to have a porous structure.

On the other hand, the mixture of the pore structure and the microcapsule blowing agent may be bonded to each other through a binder. The binder is ethylene vinyl acetate (EVA), polyvinyl alcohol (PVA), acryl (acryl), acrylamide (acrylamide), vinyl chloride (PVC), polyvinyl acetal, acrylic, It may be any of saturated polyester, polyamide, polyethylene, natural rubber, synthetic rubber, silicone, or melamine, or a mixture thereof. In this embodiment, the binder is an EVA-based aqueous emulsion adhesive.

The pore structure, the microcapsule blowing agent and the binder should be mixed at an appropriate magnification, and the binder content is relatively high. Since the binder removes moisture through the heating process described below, the weight of the binder is reduced in the porous structure after processing.

(Production example 1)

1 is a photograph of a porous structure produced by the present invention. The pore structure used in this example is silica airgel. The silica airgel was an airgel prepared by the method of 'silica airgel prepared using the method and the silica airgel prepared using the method' of the Republic of Korea Patent Publication No. 10-2015-0078955.

The thermal conductivity of the silica airgel used is 0.026 (W / mK) and the microcapsule blowing agent has a particle size of 20㎛ ~ 50㎛. The microcapsule blowing agent is CELLCOM-CAP170K (Geumyang), the initial expansion temperature is 130 ℃ ~ 150 ℃ and the maximum expansion temperature is 160 ℃ ~ 180 ℃. As the binder, an EVA-based aqueous emulsion type adhesive having a solid content of 50% was used.

The pore structure, the microcapsule blowing agent and the binder are mixed inside the container, and the silica airgel, the microcapsule blowing agent and the binder are mixed in a weight ratio of 2: 2: 10, respectively. Here, the mixing ratio of silica airgel and microcapsules is selected in consideration of both the shaping and the adiabatic effect. In the mixing ratio of silica airgel and microcapsules, when the relative content of the airgel increases, the thermal insulation effect increases but the crystallinity decreases. On the contrary, when the silica airgel content decreases relatively, the crystallization is improved, but the thermal insulation effect cannot be expected. .

The mixture is prepared by heating. The heating process consists of primary heating and secondary heating. Here, the primary heating is a drying step for removing the water and the solvent of the binder by heating the mixture, the secondary heating can be seen as a foaming step for foaming the microcapsule blowing agent contained in the mixture. Secondary heating for foaming takes about 5 to 10 minutes.

The secondary heating is made at a relatively high temperature than the primary heating, specifically, the primary heating is made at 80 ℃ ~ 150 ℃, the secondary heating is preferably made at 130 ℃ ~ 200 ℃. . For reference, in the present invention, the initial expansion temperature of the microcapsule blowing agent is 130 ℃ ~ 150 ℃, the maximum expansion temperature is 160 ℃ ~ 180 ℃ CELLCOM-CAP170K.

On the other hand, in the Preparation Example 1, the mixture of silica airgel, microcapsule blowing agent, and binder, each at a weight ratio of 2: 2: 10, is first heated to a temperature of 80 ° C to 100 ° C in a drying oven and dried. In this process, water and solvent of the binder are removed.

Subsequently, the dried mixture is placed in a container in an oven at 180 ° C. to 200 ° C., and then secondaryly heated and foamed. That is, in this process, the microcapsule foaming agent is foamed. Accordingly, the porosity of the porous structure is very high because the pores of the pore structure and the foamed pores of the microcapsule foaming agent are added. Therefore, the specific gravity of the raw material of the pore structure required to manufacture the porous structure to implement the same insulation performance can be lowered. Figure 2 is a photograph confirmed by the microscope after cross-sectional processing of the porous structure of FIG. As a result of the test, the thermal conductivity of the manufactured insulation was measured to be 0.028 (W / mK). For reference, 0.028 (W / mK), which is a thermal conductivity obtained when the present production method is applied, is almost the same as that of a conventional product, that is, a product manufactured by using only silica aerogel without foaming agent. Therefore, according to the present invention, not only the same heat insulating effect can be obtained at a relatively low cost, but also the formation of more various shapes can be easily made by giving a shaping.

Of course, if necessary, after the foaming step, a cutting step of cutting the manufactured porous structure into a predetermined form may be further included. Since the porous structure is prepared by mixing the microcapsule blowing agent and the binder in the pore structure, the powder is prevented from being blown, and at the same time, it has a crystallization, and thus the porous structure can be manufactured and cut into a specific three-dimensional shape. Reference figure 1 is a cross-sectional view of the prepared porous structure is shown. In this way, even when the porous structure is cut, the porous structure maintains a three-dimensional shape, and thus the porous structure of the present invention can be cut after cutting into various shapes.

In the foregoing description, the present invention is not necessarily limited to these embodiments, although all of the components constituting the embodiments according to the present invention are described as being combined or operating in combination. In other words, within the scope of the present invention, all of the components may be selectively operated in combination with one or more. In addition, the terms "comprise", "comprise" or "having" described above mean that the corresponding component may be inherent unless specifically stated otherwise, and thus excludes other components. It should be construed that it may further include other components instead. All terms, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art unless otherwise defined. Terms used generally, such as terms defined in a dictionary, should be interpreted to coincide with the contextual meaning of the related art, and shall not be interpreted in an ideal or excessively formal sense unless explicitly defined in the present invention.

The above description is merely illustrative of the technical idea of the present invention, and those skilled in the art to which the present invention pertains may make various modifications and changes without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention but to describe the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention.

Claims

Porous structure prepared by mixing the pore structure, the microcapsule blowing agent and the binder and then foaming through heating.
The porous structure of claim 1, wherein the pore structure is any one of silica-based nanoporous material, silica airgel, alumina-based pore material, titania-based pore material, zirconia-based pore material, or carbon-based pore material.
According to claim 2, wherein the diameter of the microcapsule blowing agent is 10 ~ 60㎛, the heating includes a primary heating and secondary heating, the primary heating is 80 ~ 150 ℃, the secondary heating is 130 ~ Porous structure made at 200 ℃.
The method of claim 1, wherein the binder is ethylene vinyl acetate (EVA), polyvinyl alcohol (PVA), acrylic (Acryl), acrylamide, vinyl chloride (PVC) ), A polyvinyl acetal (polyvinyl acetal), acrylic, saturated polyester, polyamide, polyethylene, natural rubber, synthetic rubber, silicone or melamine-based porous structure of any one or a mixture thereof.
As a method for producing a porous structure,

Adding a binder to the pore structure and the microcapsule blowing agent to form a mixture,

A drying step of heating the mixture to remove water and solvent from the binder;

And re-heating the mixture to a relatively high temperature to foam the microcapsule blowing agent.
The method of claim 5, wherein the pore structure is any one of silica-based nanoporous material, silica airgel, alumina-based pore material, titania-based pore material, zirconia-based pore material or carbon-based pore material or a mixture thereof Way.
The method of claim 6, wherein the binder is ethylene vinyl acetate (EVA), polyvinyl alcohol (PVA), acryl (acryl), acrylamide (acrylamide), vinyl chloride (PVC), polyvinyl acetal (polyvinyl) acetal), acrylic, saturated polyesters, polyamides, polyethylenes, natural rubbers, synthetic rubbers, silicones or melamines, or a mixture thereof.
The method of claim 5, wherein the mixture is heated at 80 ° C. to 150 ° C. in the drying step, and the mixture is heated at 130 ° C. to 200 ° C. in the foaming step.
According to claim 5, Porous structure manufacturing method further comprises a cutting step of cutting the porous structure produced in a predetermined form following the foaming step.
The method of claim 5, wherein the mixture is dried and foamed in a container having a predetermined shape.