WO2014116053A1

WO2014116053A1 - Method for modifying surface hydrophilicity of ptfe

Info

Publication number: WO2014116053A1
Application number: PCT/KR2014/000703
Authority: WO
Inventors: 정용호; 석동찬; 정현영
Original assignee: 한국기초과학지원연구원
Priority date: 2013-01-28
Filing date: 2014-01-24
Publication date: 2014-07-31
Also published as: CN104955884B; KR101480094B1; JP6091659B2; KR20140096526A; JP2016504480A; CN104955884A

Abstract

The present invention relates to a method for modifying the surface hydrophilicity of PTFE. Specifically, the present invention relates to a method for modifying the surface hydrophilicity of PTFE by means of a plasma treatment. More specifically, the present invention relates to a method for modifying the surface hydrophilicity of PTFE by generating plasma by means of hydrocarbon gas and a mixed gas of carbon compounds, and exposing the plasma on the surface of the PTFE. Furthermore, the present invention relates to a method for modifying the surface hydrophilicity of PTFE under atmospheric pressure conditions.

Description

Hydrophilic Modification Method of PETF Surface

The present invention relates to a method of hydrophilic modification of PTFE surfaces. Specifically, the present invention relates to a method for modifying PTFE surface hydrophilicity by plasma treatment. More specifically, the present invention relates to a method of hydrophilic modification of a PTFE surface by generating a plasma with a mixed gas of a hydrocarbon-based gas and a carbon compound and exposing it to the PTFE surface. More particularly, it relates to a method of hydrophilic modification of PTFE surface under atmospheric pressure.

Polytetrafluoroethylene (hereinafter referred to as PTFE) is a colorless, odorless white powder prepared by free radical polymerization of tetrafluoroethylene monomers. The PTFE has a heat resistance and low temperature durability of -270 to 300 degrees due to the combination of very strong C, -F, and is well known as a material having excellent chemical resistance and insulation. In addition, it has excellent non-tackiness due to strong hydrophobicity and low surface energy by -F atoms, and has a very low coefficient of friction due to repulsive force between -F atoms.

PTFE with this feature is a semicrystalline polymer discovered by accident by Roy Plunkett in 1938 and patented by DuPont in 1941 and named Teflon. Since it was first commercialized for military and industrial purposes in 1946, and since 1960, it has been widely applied to electric, electronic, medical, and energy materials as well as filter applications.

However, as mentioned above, PTFE has a lack of hydrophilicity due to strong hydrophobicity and low surface energy and difficulty in attaching to other materials, thus making it difficult to process and form for use in various industrial fields.

Thus, in recent years, various methods for increasing hydrophilicity and adhesion have been continued to facilitate the processing and molding of PTFE through modification of PTFE such as, for example, "surface modification" or "surface coating".

As a prior art for the modification of PTFE, US Pat. No. 5,300,300 discloses a method using PTFE resin for water treatment membrane applications, which discloses fluorine-containing units and hydrophilic pores within the membrane to impart hydrophilicity to the PTFE membrane. It is known to add hydrophilicity by coating with a hydrophilic fluorine containing polymer comprising a non-fluorinated vinyl monomeric unit.

In addition, Korean Patent Application No. 1994-0026594 (method for producing modified polytetrafluoroethylene and its use), including polymerization of a monomer in an aqueous medium by a suspension polymerization method using a permanganate initiator at a temperature of 60 ° C. or lower, A method for producing a polymer of tetrafluoroethylene containing perfluorine having 1 to 4 carbon atoms in the fluoroalkyl chain is disclosed.

These prior art methods of modifying PTFE have the problem of complex steps, long processes, and high costs.

On the other hand, in addition to the modification methods of PTFE disclosed through the aforementioned conventional techniques, as a method for modifying PTFE, a method of modifying the surface of a polymer material such as PTFE using plasma is used.

The method of modifying the surface of a polymer material such as PTFE using plasma is aimed at reducing the contact angle of water to the surface of the polymer material to have hydrophilicity. For example, if the contact angle is less than 90 °, the water droplets may lose their shape and hydrophilicity may appear that wets the surface of PTFE. If the contact angle is greater than 90 °, the water droplet may not wet the surface of PTFE while maintaining the shape of the sphere. And hydrophobicity, which is a unique feature of PTFE, which flows easily according to external forces.

As a method of using a plasma for modifying the surface of a polymer material such as PTFE to change the contact angle, a method such as a high voltage corona discharge and a direct current plasma discharge may be used.

The high voltage corona discharge fills the reactor with atmospheric pressure in a vacuum chamber, ionizes the reactor by electrons emitted from the electrode, and forms a plasma that has the same positive and negative charge as the electrons. It refers to a method of reacting on a surface and depositing on a surface or modifying a surface.

Japanese Laid-Open Patent Publication No. 1985-13823 is a conventional technique for modifying the surface of a polymer material such as PTFE using such a high voltage corona discharge. This patent discloses a case where the surface of vinyl chloride is treated with chlorine gas at atmospheric pressure.

The DC plasma discharge is similar to the high voltage corona discharge, but fills the reactor in the vacuum chamber with an amount of 0.01 to 5 torr, using the plasma generated through the glow discharge, that is, the ionized reactor.

As a conventional technique for modifying the surface of a polymer material such as PTFE using such a DC plasma discharge, there is Japanese Patent Laid-Open No. 1986-171740. This patent discloses a case of modifying a surface of a PMMA polymer material under argon gas pressure of 0.1 torr.

The problems of the above patents have a common problem that the contact angle reduction is not great and the surface properties are rough. There is also a problem that must be performed in a vacuum.

The present invention is to recognize the above problems and needs, and to provide a simple method for overcoming the above problems. That is, the present invention provides a method for modifying the surface of PTFE by a simple plasma treatment using a hydrocarbon gas and a carbon compound gas at atmospheric pressure.

The present invention comprises the steps of generating a plasma with a mixed gas of a hydrocarbon gas and a carbon compound; It provides a method of hydrophilic modification of the surface of PTFE, comprising exposing the PTFE to the generated plasma. The hydrocarbon gas is preferably acetylene, and the carbon compound gas is preferably carbon dioxide.

The present invention is characterized in that the amount of carbon dioxide supplied is greater than the amount of acetylene supplied.

The present invention is characterized in that the acetylene supply amount is a maximum of 0.08, based on the supply amount of the carbon dioxide 1. Excessive acetylene feed would rather reduce the hydrophilicity of the surface of the PTFE and cause discoloration.

In the hydrophilic character, the acetylene supply amount has a threshold value up to 0.08, based on the supply amount of carbon dioxide 1, but the supply of excess acetylene discolors PTFE.

The maximum supply amount of acetylene gas, which is free from discoloration of PTFE and provides the maximum hydrophilicity value (lowest contact angle), is 0.03, based on the supply amount 1 of the carbon compound gas.

The present invention is characterized in that the plasma treatment is performed under atmospheric pressure.

In the present invention, the PTFE material may be in various forms, for example powder, sheet and block.

1 is a schematic diagram illustrating a DBD type plasma generating apparatus of the present invention.

2 is a graph showing the results of the first experiment.

3 is a graph showing the results of the second experiment.

Fig. 4 is a photograph of the surface of PTFE after plasma treatment when the gas supply ratio of carbon dioxide and acetylene gas is 1: 0.02.

Figure 5 is a micrograph of the powder of the hydrophilized PTFE surface of the powder using the tubular plasma module of the present inventors Korean Application No. 10-2012-0078234 using the gas combination used in the first experiment.

1. 제 1 실험1. First Experiment

A DBD-type plasma generator operating under atmospheric pressure was prepared. It will be apparent to those skilled in the art that various types of DBD types may be used. Examples of various types of DBD type devices are shown in FIG. 1. As a gas generating plasma, a mixture of nitrogen, carbon dioxide, and acetylene gas was supplied to the plasma generating region, and high frequency power of 30 kH and 1 kW was applied to the high voltage electrode 210.

The gas feed rate was 250 lpm for nitrogen, acetylene for 0.1 lpm, and carbon dioxide for 0.01 to 1 lpm.

The PTFE sheet was moved to the plasma generating region in the plasma generator at a rate of 10 mm / second. The gap between the sheet and the DBD module was 4 mm.

The hydrophilic modification of the plasma treated PTFE was confirmed by a contact angle measuring method (Goniometer, KRUSS DSA100) according to the water droplet contact angle measuring method.

After performing this experiment twice, the average of each measured contact angle was recorded, and the result is referred to FIG. 2.

As shown in Figure 2, it can be seen that the contact angle is improved when the supply amount of carbon dioxide is more than acetylene. In addition, it can be seen that the surface hydrophilic modification of PTFE is improved as the supply amount of carbon dioxide is increased.

2. 제 2 실험2. 2nd experiment

The first experiment and the experimental method were the same, and only the gas supply rate was changed as follows.

The gas feed rate was 250 lpm for nitrogen, 1 lpm for carbon dioxide, and acetylene for 0.02 to 0.1. The result is shown in FIG.

As shown in FIG. 3, the surface hydrophilicity of PTFE is improved as the supply amount of acetylene increases with respect to the carbon dioxide supply amount 1, but it can be seen that the surface hydrophilicity of PTFE is lowered from the supply amount of 0.08 or more with respect to the carbon dioxide supply amount 1.

4 is a photograph of the surface of PTFE after plasma treatment when the gas supply ratio of carbon dioxide and acetylene gas is 1: 0.02 in the above experiment. Through the second experiment, it was confirmed that when the excess acetylene gas was supplied, the PTFE surface was discolored. 5 shows this.

Claims

Generating a plasma with a mixed gas of a hydrocarbon gas and a carbon compound;

Exposing PTFE to the generated plasma;

Hydrophilic Modification of PTFE Surface.
The method of claim 1,

The hydrocarbon gas is acetylene,

Hydrophilic Modification of PTFE Surface.
The method according to claim 1 or 2,

The carbon compound gas is carbon dioxide,

Hydrophilic Modification of PTFE Surface.
The method of claim 3, wherein

The supply amount of carbon dioxide is greater than the acetylene supply amount,

Hydrophilic Modification of PTFE Surface.
The method of claim 3, wherein

The acetylene supply amount is 0.08 maximum, based on the supply amount of carbon dioxide 1,

Hydrophilic Modification of PTFE Surface.
The method of claim 5,

The acetylene supply amount is a maximum of 0.03, based on the supply amount of carbon dioxide 1,

Hydrophilic Modification of PTFE Surface.
The method of claim 1,

The plasma treatment is performed under atmospheric pressure,

Hydrophilic Modification of PTFE Surface.
The method of claim 1,

The PTFE material includes a powder, a sheet and a block,

PTFE surface hydrophilic modification method.