[Invention Title]

OIL COLLECTING STRUCTURE AND A PREPARATION METHOD THEREOF

[Technical Field]

The present invention relates to an oil collecting structure and a preparation method thereof.

[Background Art]

The sea takes up 70% of the Earth' s total surface area and abounds with a variety of biological resources and mineral resources, and therefore the sea is a repository of resources that humans should conserve its ecological environment. However, the marine ecosystem has been rapidly ruined due to various causes including oil spills from the accidents of large-sized oil tankers and the accidents occurred in transit by land, as well as factory wastewater flowing from large-scale industrial complexes, domestic wastewater discharged from large cities, and fertilizer ingredients and excrement used for agricultural and stockbreeding activities.

In particular, oil spills from ships involved in marine accidents may bring irreparable calamities to humanity because the spills destroy the ocean ecosystem over a long period of time even after the oil is collected as well as at the beginning of the oil spill accidents. The spilled oil can be partially removed by means of control and cleanup works. But, oil spills generally remain in the marine environment throughout a complicated weathering process doing a fatal damage to varied marine life. Thus, the only way to minimize damage in case of oil spills is an effective and prompt cleanup work.

Meanwhile, methods for removing oil leaked into the seas, streams, and rivers from oil spills caused by navigating and sinking of ships, accidents of oil tankers on the land, oil-refining facilities, oil storages, oil pipelines, gas stations, etc. include oil removal apparatus utilizing methods that absorb oil by means of centrifugal separation or mechanically, chemical/biochemical treatments, spilled oil combusting methods, etc.

<6> Particularly, the methods used include an application of oil emulsifier that neutralizes oil, a method of absorbing oil with oil absorbing fabrics and then collecting and treating the oil, and a method of installing an oil diffusion preventive fence to prevent oil from spreading along the surface of the water.

<7> However, the absorption methods using mechanical apparatuses may be ineffective to treat oil as water can be absorbed along with oil. And the methods for removing waste oil from the surface of the water by using chemicals may have a problem of secondary environmental pollution due to remaining oil sediment even if oil is removed from the surface of the water, because oil is coagulated together with the chemicals. Also, the method of spreading the oil emulsifier may neutralize oil but potentially involve water pollution due to chemical components of the oil emulsifier and the method of installing the oil diffusion preventive fence may have a shortcoming in removing oil floating on the surface of the water.

<8> To solve these problems above, oil absorbents absorbing oil exclusively are used. And these absorbents use oleophilic nonwoven fabrics or ones made in the form of mat, e.g. kapok, using plants or animal hair presenting oleophilic property themselves.

<9> The oleophilic nonwoven fabrics, in general, are a kind of pressed cotton made by needle-punching a thinly spun polypropylene fiber. The polypropylene fiber is oleophilic and effective in absorbing oil as the fiber may have a huge surface area due to the entanglement of the fiber. But, the absorbents such as the oleophilic nonwoven fabrics may produce a toxic gas in the process of incineration treatment after oil absorption.

:io> In the case of domestic oil spill accidents, oil fences are used as a general treatment process. In order to prevent oil from spreading, huge fences, i.e. oil fences, are installed in the affected areas by the accidents to confine oil in the fences and skim oil using a skimmer, a tool for skimming oil lumps, or to absorb oil by absorbers. But, a thin film of oil called oil film may still exist on the surface of the areas even after oil is skimmed, which may ruin fish farms by blocking the supply of oxygen into the water. Thus, eliminating the oil film may be one of the most cost and effort consuming processes in oil spill accidents in the seas.

<ii> Korean Patent No. 10-103211 discloses a method for absorbing oil by mixing polypropylene and feathers of ducks, geese, chickens, etc. and making the mixture felts to absorb oil spilled into the seas or rivers.

<i2> Korean Patent No. 10-0725240 discloses a method for absorbing oil spills using a phenol resin foaming agent as oil absorbent.

<i3> US Patent No. 6,391,120 discloses a method for absorbing oil using coconut coir pith.

<14> US Patent No. 7,655,149 discloses a method for absorbing oil using kenaf balls.

<i5> US Patent No. 7,914,672 discloses a method of freezing oil by means of critical fluid and removing the oil.

<i6> However, the preceding disclosures may be utilized locally to remove and/or collect oil but still lack of economic feasibility.

<i7> Accordingly, the inventors of the present invention completed the present invention by developing a structure capable of separating and collecting oil exclusively while passing water through a mesh type scaffold on which a hydrophilic polymer layer is coated, in the course of the research into effective methods for collecting oil.

<18>

[Disclosure]

[Technical Problem]

<19> The object of the present invention is to provide an oil collecting structure and a method for preparing the same.

:20>

[Technical Solution]

2i> In order to achieve the aforementioned object, the present invention provides an oil collecting structure, wherein a hydrophilic polymer layer is coated on the surface of a mesh type scaffold and a water-resistant fortifier is additionally coated thereupon. <22> Further, the present invention provides a method for preparing the oil collecting structure including the following steps of: coating a hydrophilic polymer layer on the surface of a mesh type scaffold (step 1); and spraying a water-resistant fortifying solution onto the surface of the hydrophilic polymer layer coated at step 1 (step 2).

<23> Furthermore, the present invention provides a method for collecting oil existent on the surface of the water by using the oil collecting structure.

<24>

[Advantageous Effects]

<25> According to the present invention, the oil collecting structure may collect oil exclusively by passing water through the structure but separating oil exclusively, through which oil existent on the surface of the water may be collected without having a secondary pollution. Further, cross-linking the hydrophilic polymer formed on the surface of the structure to prevent the hydrophilic polymer from being removed easily by water may extend the period of using the structure of the present invention.

<26>

[Description of Drawings]

<27> FIG. 1 is a drawing schematically illustrating the oil collecting structure of the present invention.

<28> FIG. 2 is a graph illustrating changes in durability according to the cross-linkage of a hydrophilic polymer.

<29> FIG. 3 is a graph illustrating changes in durability according to the addition of a water-resistant fortifier.

<30> FIG. 4 and FIG. 5 are graphs obtained as a result of the measurement of the contact angles of the hydrophilic polymer layers in Examples 1, 2, 3, 5,

6, and 7; and of the contact angles of the hydrophilic polymer layers in

Comparative Examples 1 to 6.

3i> FIG. 6 are images showing the integration of an oil collecting structure, a beaker, and a transparent container for the evaluation of oil separating characteristics.

32> FIG. 7 is an image showing a result of oil separation using a mesh on which hydrophilic polymer is not coated (control group

<33> FIG. 8 is an image showing a result of oi separation using the structure prepared in Comparative Example 3.

<34> FIG. 9 is an image showing a result of oi separation using the structure prepared in Comparative Example 2.

<35> FIG. 10 is an image showing a result of oi separation using the structure prepared in Comparative Example 1.

<36> FIG. 11 is an image showing a result of oi separation using the structure prepared in Example 3.

<37> FIG. 12 is an image showing a result of oi separation using the structure prepared in Example 2.

<38> FIG. 13 is an image showing a result of oi separation using the structure prepared in Example 1.

<39> FIG. 14 is an image showing a result of oi separation using the structure prepared in Comparative Example 8.

<40> FIG. 15 is an image showing a result of oi separation using the structure prepared in Comparative Example 9.

<4i> FIG. 16 is an image showing a result of oi separation using the structure prepared in Comparative Example 10.

<42> FIG. 17 is an image showing a result of oi separation using the structure prepared in Example 4.

<43> FIG. 18 is an image showing a result of oi separation using the structure prepared in Example 5.

<44> FIG. 19 is an image showing a result of oi separation using the structure prepared in Example 6.

i 5> FIG. 20 is an image showing a result of oi separation using the structure prepared in Example 7.

-46>

47> description of Figures>

48> 10: oil collecting structure

49> 11: mesh type scaffold

50> 12: hydrophilic polymer layer <51>

[Best Mode]

<52> The present invention provides an oil collecting structure, wherein a hydrophilic polymer layer is coated on the surface of a mesh type scaffold and a water-resistant fortifier is coated thereupon. The oil collecting structure according to the present invention is schematically provided in FIG. 1.

<53> Referring to FIG. 1, an oil collecting structure (10) according to the present invention has a hydrophilic polymer layer (12) coated on the surface of a mesh type scaffold (11). As the hydrophilic polymer layer (12) is formed as a layer on the surface of the scaffold, water may pass through the openings of the mesh type scaffold while oil may not pass through and therefore exclusively oil may be collected effectively.

<54> For the mesh type scaffold (11), a metal mesh, nonwoven fabric, etc. may be used. Considering the strength of the scaffold, the metal mesh may desirably be used, but not limited thereto. In addition, the mesh type scaffold may be in the shape of sphere or polygon and may desirably be in the shape of circle or tetragon, but not limited thereto.

<55> The metal mesh may desirably be of a metal material such as stainless steel, aluminum, and titanium. Using the stainless steel whose strength and corrosion resistance against water are desirable, which is also inexpensive, may be more preferable, but not limited thereto.

<56> For the mesh type scaffold, the 10 to 500 mesh scaffold may desirably be used. If the meshes of the scaffold exceed 500, the meshes may be clogged up by hydrophilic polymer due to the excessively small size of the meshes. But, if the meshes of the scaffold are less than 10, oil may not be separated exclusively due to the excessively large size of the meshes.

57> In the meantime, for the hydrophilic polymer in the oil collecting structure according to the present invention, one or more types of polymer may be used, which may be selected from a group consisting of polyethylene glycol (PEG), polyvinyl alcohol (PVA), polyvinyl acetate (PVAc), polyvinyl pyrrol idone (PVP), polyethylene oxide (PE0), and carboxymethyl cellulose (CMC) .

<58> Further, a water-resistant fortifier is coated and formed on the hydrophilic polymer layer and may be formed on, at least, part of the surface of the hydrophilic polymer layer. As the water-resistant fortifier is coated on the hydrophilic polymer layer, water resistance may be improved further and thus the hydrophilic polymer layer may be prevented from being come off or dissolved by water, and therefore the period of using the structure may be extended further.

<59> For the water-resistant fortifier, aluminum sulfate or ethylene carbonate may be used, but using the both together may be more desirable, but not limited thereto. Materials reactive with hydrophilic polymer to improve water resistance of the hydrophilic polymer may also be used properly.

<60> Further, the oil collecting structure according to the present invention may have a reinforced water resistance and hydrophilic property sufficient to separate oil by using a water-resistant fortifier such as ethylene carbonate because ester group of carbonate helps possess hydrophilic property and facilitate the formation of cross-linked structure, and makes the fortifier insoluble in water.

<6i> In the meantime, the hydrophilic polymer layer may desirably be cross- linked. By means of cross-linkage, the hydrophilic polymer layer may have a certain degree of strength and water resistance, which may extend the period of using the oil collecting structure according to the present invention.

<62> Furthermore, the present invention provides a method for preparing the oil collecting structure, which includes the following steps of: coating a hydrophilic polymer layer on the surface of a mesh type scaffold (step 1); and spraying a water-resistant fortifying solution onto the surface of the hydrophilic polymer layer coated at step 1 (step 2).

63> Hereinafter, each step of the preparation method for the oil collecting structure according to the present invention will be described in detail.

54> According to one embodiment, step 1 coats a hydrophilic polymer layer on the surface of a mesh type scaffold.

S5> For the mesh type scaffold, a metal mesh or nonwoven fabric may be used and such materials as stainless steel, aluminum, and titanium may desirably be used for the strength of the scaffold. Among these, stainless steel, which is inexpensive and whose strength and corrosion resistance against water are desirable, may desirably be used, but not limited thereto.

<66> And for the mesh type scaffold, a 10 to 500 mesh scaffold may desirably be used. If the meshes of the scaffold exceed 500, the meshes may be clogged up by hydrophilic polymer due to the excessively small size of the meshes. But, if the meshes of the scaffold are less than 10, separating oil may be difficult due to the excessively large size of the meshes.

<67> Further, coating the hydrophilic polymer layer at step 1 may desirably be performed by preparing a polymer solution after dissolving one or more types of polymer selected from a group consisting of polyethylene glycol (PEG), polyvinyl alcohol (PVA), polyvinyl acetate (PVAc), polyvinyl pyrrol idone (PVP), polyethylene oxide (PE0), and carboxymethyl cellulose (CMC) by a solvent and by coating the prepared polymer solution on the mesh type scaffold.

<68> The polymer solution may desirably comprise 10 to 50 wt% hydrophilic polymer. If the polymer solution includes less than 10 wt% hydrophilic polymer, a hydrophilic polymer layer may be formed excessively thinly and thus may not have hydrophilic property sufficient to separate oil. But, if the polymer solution includes over 50 wt hydrophilic polymer, coating on the mesh type scaffold may not be easy due to the excessive amount of the hydrophilic polymer as included.

i69> According to one embodiment, step 2 sprays a water-resistant fortifying solution onto the surface of the hydrophilic polymer layer coated at step 1.

:70> The water-resistant fortifier, which is used to improve water resistance of the hydrophilic polymer layer, may improve the water resistance of the hydrophilic polymer layer and thus may extend the period of using the oil collecting structure.

7i> For the water-resistant fortifier, aluminum sulfate or ethylene carbonate may be used, but using the both together may be more desirable, but not limited thereto. Materials reactive with hydrophilic polymer to improve water resistance of the hydrophilic polymer may also be used properly.

<72> The water-resistant fortifying solution may desirably comprise 10 to 20 wt% water-resistant fortifier. If the water-resistant fortifying solution includes less than 10 wt% water-resistant fortifier, the fortifying effect by the water-resistant fortifier may not be fully realized. But, if the water- resistant fortifying solution includes over 20 wt% water-resistant fortifier, hydrophilic property may deteriorate while water resistance may be reinforced due to the excessive inclusion of the water-resistant fortifier.

<73> According to the present invention, the preparation method for the oil collecting structure may additionally include, prior to step 2 of applying the water-resistant fortifier, a step of cross-linking the hydrophilic polymer coated at step 1. Through the cross-1 inkage, the strength and water resistance of the hydrophilic polymer layer may be improved, which may accordingly extend the usage life of the oil collecting structure prepared according to the preparation method disclosed in the present invention.

<74> The cross-linkage may desirably be performed by means of irradiation, and the irradiation may desirably be performed with the radiation dose of 10 to lOOkGy. If the irradiation is performed with the dose of less than lOkGy, hydrophilic polymer may not be efficiently cross-linked. But, if the irradiation is performed with the dose of over lOOkGy, economic losses may be incurred due to the excessive dosage of radiation.

<75> Further, the present invention provides a method for collecting oil existent on the surface of the water using the oil collecting structure.

;76> The oil collecting structure in which a hydrophilic polymer layer is coated on the surface of a mesh type scaffold, through which water is passed but oil is not passed, may be effective to collect oil exclusively. By using the oil collecting structure to collect oil existent on the surface of the water, the oil collecting structure may replace conventional oil absorbents, oil fence, etc. and may collect oil effectively.

77> Oil may be collected by equipping ships with the oil collecting structure at the rear of the ships and simply navigating the ships towards an oil spilled area may be effective to collect oil. But, the collecting method of the present invention is not limited thereto and a proper means or tools to which the structure can be applied may be used to collect oil.

<78>

<79> Hereinafter, the present invention will now be described in greater detail with examples. However, the following examples are intended only to be illustrative, and not to limit the scope of the claims.

<80>

<8i> <Example 1> Preparation of Oil Collecting Structure 1

<82> Step l: By using a stirrer, 20 wt polyvinyl alcohol, 15 wt% polyethylene glycol, and 65 wt% purified water were stirred at a speed of 2000rpm for 1 hour, and then the product of the stirring was coated on a stainless steel mesh with 200 meshes. Afterwards, a hydrophilic polymer layer was formed by drying the mesh in an oven at a temperature of 80 ^° C for approximately 1 hour.

<83> Step 2: By using a stirrer, 10 wt% aluminum sulfate, 5 wt% ethylene carbonate, and 85 wt% purified water were stirred at a speed of 500rpm for 1 hour, and then the product of the stirring was applied onto the hydrophilic polymer layer formed at step 1. Afterwards, an oil collecting structure according to the present invention was prepared by drying the mesh in an oven at a temperature of 80 ^° C for approximately 1 hour.

<84>

<85> <Example 2> Preparation of Oil Collecting Structure 2

;86> An oil collecting structure was prepared by performing in the same manner as Example 1, except for the differences at step 2 in Example 1 that 10 wt aluminum sulfate, 3 wt ethylene carbonate, and 87 wt% purified water were stirred and then the product of the stirring was sprayed onto a hydrophilic polymer layer.

87>

88> <Example 3> Preparation of Oil Collecting Structure 3

^9> An oil collecting structure was prepared by performing in the same manner as Example 1, except for the differences from step 2 in Example 1 that 10 wt aluminum sulfate, 1 wt% ethylene carbonate, and 89 wt purified water were stirred and then the product of the stirring was sprayed onto a hydrophilic polymer layer.

<90>

<9i> <Example 4> Preparation of Oil Collecting Structure 4

<92> An oil collecting structure was prepared by performing in the same manner as Example 1, except for the difference from step 1 in Example 1 that 20 wt% polyacrylic acid was used instead of polyvinyle alcohol and the difference from step 2 in Example 1 that 10 wt% aluminum sulfate and 90 wt% purified water were stirred.

<93>

<94> <Example 5> Preparation of Oil Collecting Structure 5

<95> An oil collecting structure was prepared in the same manner as Example

3, except for the difference from step 1 in Example 3 that 20 wt% polyacrylic acid was used instead of polyvinyle alcohol.

<96>

<97> <Example 6> Preparation of Oil Collecting Structure 6

<98> An oil collecting structure was prepared in the same manner as Example

2, except for the difference from step 1 in Example 1 that 20 wt% polyacrylic acid was used instead of polyvinyle alcohol.

<99>

ioo> <Example 7> Preparation of Oil Collecting Structure 7

ioi> An oil collecting structure was prepared in the same manner as Example

1, except for the difference from Example 1 that 20 wt% polyacrylic acid was used instead of polyvinyle alcohol.

02>

03> <Example 8> Preparation of Oil Collecting Structure 8

04> Step 1: By using a stirrer, 15 wt% polyacrylic acid, 15 wt% polyethylene glycol, and 70 wt purified water were stirred at a speed of 2000rpm for 1 hour, and then the product of the stirring was coated on a stainless steel mesh with 200 meshes. Afterwards, a hydrophilic polymer layer was formed by drying the mesh in an oven at a temperature of 80 ^° C for approximately 1 hour. <i05> Step 2: By using a stirrer, 10 wt aluminum sulfate and 90 wt% purified water were stirred at a speed of 500rpm for 1 hour, and then the product of the stirring was applied onto the hydrophilic polymer layer formed at step 1. Afterwards, an oil collecting structure according to the present invention was prepared by drying the mesh in an oven at a temperature of 80 ^° C for approximately 1 hour.

<106>

<i07> <Example 9> Preparation of Oil Collecting Structure 9

<io8> An oil collecting structure was prepared in the same manner as Example

8, except for the differences from step 2 in Example 8 that 10 wt aluminum sulfate, 1 wt% ethylene carbonate, and 89 wt% purified water were stirred and then the product of the stirring was applied onto a hydrophilic polymer 1 ayer .

<109>

<iio> <Example 10> Preparation of Oil Collecting Structure 10

<ui> An oil collecting structure was prepared in the same manner as Example

8, except for the differences from step 2 in Example 1 that 10 wt% aluminum sulfate, 3 wt% ethylene carbonate, and 87 wt% purified water were stirred and the product of the stirring was applied onto a hydrophilic polymer layer.

112>

ii3> <Example 11> Preparation of Oil Collecting Structure 11 ·

ii4> An oil collecting structure was prepared in the same manner as Example

8, except for the differences from step 2 in Example 8 that 10 wt% aluminum sulfate, 5 wt% ethylene carbonate, and 85 wt% purified water were stirred and then the product of the stirring was applied onto a hydrophilic polymer layer .

15>

i6> <Example 12> Preparation of Oil Collecting Structure 12

|i7> Step 1: By using a stirrer, 10 wt% polyacrylic acid, 15 wt% polyethylene glycol, and 75 wt purified water were stirred at a speed of 2000rpm for 1 hour, and then the product of the stirring was coated on a stainless steel mesh with 200 meshes. Afterwards, a hydrophilic polymer layer was formed by drying the mesh in an oven at a temperature of 80 ^° C for approximately 1 hour.

<ii8> Step 2'· By using a stirrer, 10 wt% aluminum sulfate and 90 wt% purified water were stirred at a speed of 500rpm for 1 hour, and then the product of the stirring was applied onto the hydrophilic polymer layer formed at step 1. Afterwards, an oil collecting structure according to the present invention was prepared by drying the mesh in an oven at a temperature of 80 ^° C for approximately 1 hour.

<119>

<i20> <Example 13> Preparation of Oil Collecting Structure 13

<i2i> An oil collecting structure was prepared in the same manner as Example

12, except for the differences from step 2 in Example 12 that 10 wt% aluminum sulfate, 1 wt% ethylene carbonate, and 89 wt% purified water were stirred and then the product of the stirring was applied onto a hydrophilic polymer 1 ayer .

<122>

<i23> <Example 14> Preparation of Oil Collecting Structure 14

<i24> An oil collecting structure was prepared in the same manner as Example

12, except for the differences from step 2 in Example 12 that 10 wt% aluminum sulfate, 3 wt% ethylene carbonate, and 87 wt% purified water were stirred and then the product of the stirring was applied onto a hydrophilic polymer 1 ayer .

125>

i26> <Example 15> Preparation of Oil Collecting Structure 15

i27> An oil collecting structure was prepared in the same manner as Example

12, except for the differences from step 2 in Example that 10 wt% aluminum sulfate, 5 wt% ethylene carbonate, and 85 wt purified water were stirred and then the product of the stirring was applied onto a hydrophilic polymer 1 ayer .

28>

29> Comparative Example 1>

30> By using a stirrer, 20 wt polyvinyle alcohol and 80 wt purified water were stirred at a speed of 2000rpm for 1 hour and then the product of the stirring was coated onto a stainless mesh with 200 meshes. Afterwards, a hydrophilic polymer layer was formed by drying the mesh in an oven at a temperature of 80 ^° C for approximately 1 hour.

<I31>

<i32> Comparative Example 2>

<i33> Comparative Example 2 was performed in the same manner as Comparative

Example 1, except for the differences from Comparative Example 1 that 15 wt% polyvinyle alcohol and 85 wt% purified water were stirred and then the product of the stirring was coated.

<134>

<i35> Comparative Example 3>

<i36> Comparative Example 3 was performed in the same manner as Comparative

Example 1, except for the differences from Comparative Example 1 that 10 wt% polyvinyle alcohol and 90 wt% purified water were stirred and then the product of the stirring was coated.

;137>

:i38> Comparative Example 4>

i39> Comparative Example 4 was performed in the same manner as Comparative

Example 1, except for the differences from Comparative Example 1 that 5 wt% polyvinyle alcohol and 95 wt% purified water were stirred and then the product of the stirring was coated.

I40>

i4i> Comparative Example 5>

42> Comparative Example 5 was performed in the same manner as Comparative

Example 1, except for the differences from Comparative Example 1 that 20 wt% polyvinyle alcohol, 5 wt% polyethylene glycol, and 75 wt purified water were stirred and then the product of the stirring was coated.

>

Ά> Comparative Example 6>

i5> Comparative Example 6 was performed in the same manner as Comparative

Example 1, except for the differences from Comparative Example 1 that 20 wt% polyvinyle alcohol, 10 wt% polyethylene glycol, and 70 wt% purified water were stirred and then the product of the stirring was coated.

<146>

<147> Comparative Example 7>

<i48> Comparative Example 7 was performed in the same manner as Comparative

Example 1, except for the differences from Comparative Example 1 that 20 wt% polyvinyle alcohol, 15 wt% polyethylene glycol, and 65 wt% purified water were stirred and then the product of the stirring was coated.

<149>

<i50> Comparative Example 8>

<i5i> Comparative Example 8 was performed in the same manner as Comparative

Example 1, except for the differences from Comparative Example 1 that 20 wt% polyacrylic acid, 15 wt polyethylene glycol, and 65 wt% purified water were stirred and then the product of the stirring was coated.

<152>

<i53> Comparative Example 9>

<i54> Comparative Example 9 was performed in the same manner as Comparative

Example 1, except for the differences from Comparative Example 1 that 15 wt% polyacrylic acid, 15 wt% polyethylene glycol, and 70 wt purified water were stirred and then the product of the stirring was coated.

155>

i56> Comparative Example 10>

157> Comparative Example 10 was performed in the same manner as Comparative

Example 1, except for the differences from Comparative Example 1 that 10 wt% polyacrylic acid, 15 ^' wt polyethylene glycol, and 75 wt% purified water were stirred and then the product of the stirring was coated.

58>

59> Compositions of the hydrophilic polymer solution and water-resistant fortifying (aluminum sulfate and ethylene carbonate) solution, which are used in Examples 1 to 15 and Comparative Examples 1 to 10, are listed below.

50>

[Table 1]

Analysis <164>

<165> (1) Measurement of Durability Changes of Hydrophilic Polymer according to Cross-linkage

<i66> In order to measure changes in water resistance, i.e. durability of hydrophilic polymer, according to the cross-linkage of the hydrophilic polymer, a hydrophilic polymer layer was formed on a metal scaffold and the product of which was cross-linked with the electron irradiation of 50kGy, and the product was cleaned at a speed of lOOOrpm in a purified water tank for 24 hours and then the product was dried to measure the changes of weight before/after the cleaning and to analyze residuals of the hydrophilic polymer. The results of the measurement and analysis are provided in FIG. 2.

<i67> (Sample No. 1: 20 wt% polyvinyle alcohol and 80 wt% purified water;

Sample No. 2: 20 wt% polyvinyle alcohol, 5 wt% polyethylene glycol, and 75 wt% purified water; Sample No. 3: 20 wt% polyvinyle alcohol, 10 wt% polyethylene glycol, and 70 wt% purified water; Sample No. 4: 20 wt% polyvinyle alcohol, 10 wt polyethylene glycol, and 70 wt purified water; Sample No. 4: 20 wt polyvinyle alcohol, 15 wt% polyethylene glycol, and 65 wt% purified water)

168> Referring to FIG. 2, in the cases of Samples No. 1 to 4, to which radiation is not exposed, the residuals after the cleaning are approximately 10%. Based on this, it is confirmed that most of the hydrophilic polymer layer was washed off during the cleaning process. On the other hand, in the cases of Samples No. 1 to 4, which are cross-linked, the residuals after the cleaning are approximately 90%. Based on this, it is confirmed that, when the hydrophilic polymer is cross-linked, water resistance is improved and accordingly the hydrophilic polymer is not easily washed off by water.

69>

70> (2) Measurement of Durability Changes of Hydrophilic Polymer according to the Addition of Water-Resistant Fortifier

71 >

i2> The hydrophilic polymer layer added with the water-resistant fortifier in Examples 4 to 15 and the hydrophilic polymer layer not added with the water-resistant fortifier in Comparative Examples 8 to 10 were cleaned at a speed of lOOOrpm in a purified water tank for 24 hours, and the products of which ware dried to measure the changes in weight before/after the cleaning and to analyze the hydrophilic polymer residuals. The result of the measurement and analysis are provided in FIG. 3.

<i73> Referring to FIG. 3, the hydrophilic polymer layers in Examples 4 to 15 presented a much higher residual quantity ratio compared to the hydrophilic polymer layers in Comparative Examples 8 to 10. Further, when the content of the added water-resistant fortifier (ethylene carbonate) increases, the residuals increase. Based on this, it is confirmed that durability, i.e. water-resistance, of the hydrophilic polymer is improved by the water- resistant fortifier.

<174>

<i75> (3) Analysis of Contact Angle of Hydrophilic Polymer Layer

<176> Contact angles of the hydrophilic polymer layers formed in Examples 1,

2, 3, 5, 6, and 7 and of the hydrophilic polymer layers formed in Comparative Examples 1 to 7 were analyzed and the results of the analysis are provided in FIG. 4 and FIG. 5.

177> Referring to FIG. 4, all the hydrophilic polymer layers formed in

Examples 1 to 6 had a contact angle of maximum 40 degrees, which presents hydrophilic property. When the amount of added ethylene carbonate, as a water-resistant fortifier, increases, the contact angle decreases.

i78> Referring to FIG. 5, the contact angle of the formed hydrophilic polymer layers is lowered, when the content of the hydrophilic polymer increases according to Comparative Examples 1 to 7.

79> Therefore, it is confirmed that a problem of deteriorating hydrophilic property due to the excessive addition of the fortifier can be prevented by adjusting the amount of the added water-resistant fortifier, and that the contact angle, i.e. degree of hydrophilic property, was changed according to the content of the hydrophilic polymer.

Experimental Example 1> Evaluation of Oil Separating Characteristics <182> (1) Evaluation of Characteristics of Oil Separation by means of

Hydrophilic Polymer Film 1

<i83> In order to evaluate the characteristics of oil separation by means of hydrophilic polymer film, a solution mixed with distilled water of 100ml and soybean oil of 100ml was separated by using the oil collecting structures prepared in Examples 1 to 3 and in Comparative Examples 1 to 3. As shown in FIG. 6, the separation was performed by integrating an oil collecting structure, a beaker, and a transparent container, and the results of the separation are provided in FIGs. 7 to 13.

<i84> Referring to FIG. 7, a stainless mesh with 200 meshes (control group) on which the hydrophilic polymer layer was not coated was not able to separate oil at all.

<i85> Referring to FIGs. 8 to 10, the structures prepared in Comparative

Examples 1 to 3 were able to separate oil partially, but a complete separation was not made. It is considered that a sufficient degree of hydrophilic property to separate oil was not obtained due to an insufficient content of hydrophilic polymer.

:i86> On the contrary, as shown in FIGs. 11 to 13, the structures prepared in

Examples 1 to 3 were able to separate most of oil. Based on this, it is confirmed that when the amount of added ethylene carbonate as a water- resistant fortifier increases, oil can be separated more desirably.

i87> Based on the results above, it is confirmed that oil can be separated effectively by using the oil collecting structure according to the present invention, and that oil can be separated more effectively with the addition of ethylene carbonate.

88>

89> (2) Evaluation of Characteristics of Oil Separation by means of

Hydrophilic Polymer Film 2

?o> A solution mixed with distilled water of 100ml and soybean oil of 100ml was separated by using the oil collecting structures prepared in Examples 4 to 7 and in Comparative Examples 8 to 10, and the results of the separation are provided in FIGs 14 to 20. <i 9 i> Referring to FIGs. 14 to 16, the structures prepared in Comparative

Examples 8 to 10 were able to separate oil partially, but were not able to separate oil from the mixed solution completely.

<i92> On the contrary, as shown in FIGs. 17 to 20, the oil collecting structures prepared in Examples 4 to 7 were able to separate oil from the mixed solution completely.

<i93> Based on the results . above, it is confirmed that oil separating capability as well as water resistance of the hydrophilic polymer film were improved by the addition of water-resistant fortifier, and it is considered that the oil collecting structure according to the present invention may be used effectively for collecting oil.

<1 4>

<i95> (3) Evaluation of Characteristics of Oil Separation according to the

Mesh Size of the Mesh Type Scaffold

<i96> In order to analyze the separation speed according to the mesh size of the mesh type scaffold, the mesh sizes were varied from 50 to 400 as seen in Examples 1 and 4, and the oil separation speeds were analyzed based on this. d 7> The analysis was performed after integrating the oil collecting structures prepared in Examples 1 and 4 and a beaker and a transparent container, and then providing the mixture of 50ml water and 50ml soybean oil stirred for one hour by using a stirrer, and the results thereof are provided in Table 2 below.

198>

199> [Table 2]

oi> As shown in Table 2 above, both the water and the soybean oil were all passed through the 50 mesh scaffold and accordingly separation did not occur due to the excessively large size of the mesh. On the contrary, the 100 to 400 mesh size scaffolds were all able to separate the soybean oil from the water .

Based on the results above, it is confirmed that, if the mesh size is denser, the separation time tends to be longer, and thus it is considered that the oil separation time can be controlled effectively by adjusting the mesh size of the mesh type scaffold.