JPH0794567B2 - Method for producing molded article having fluorine-containing thin surface layer - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention has properties such as lubricity, water repellency, light transmission, weather resistance, and antistatic properties, and is therefore used in various applications requiring these properties. The present invention relates to a method for producing a molded article having a thin surface layer containing fluorine.

[0002]

2. Description of the Related Art Many attempts have been made in the past to provide a base material made of a polymer material with a surface layer having characteristics not possessed by the base material, and it is now widely used due to its simplicity. The method is a method of forming a fluorine-containing additive-containing surface layer on a substrate by wet-coating a solution of a polymer containing a fluorine-containing additive on a substrate made of the same polymer in the air and heating and drying. However, this method has the following drawbacks.

(A) Since there is a wet process for coating a base material with a polymer solution containing a fluorine-based additive when forming the surface layer, it is necessary to heat and dry the coated polymer solution, and therefore the melting point and transition point are required. Thermoplastic polymer sheets and plastic molded products having a low viscosity cannot be used as a substrate because the dimensional stability is impaired. (B) Recently, by vacuum evaporation method, sputtering method, ion plating method, etc., a molded product having an extremely thin and uniform surface layer can be industrially obtained regardless of the shape of a flat surface, a spherical surface, an uneven surface, or the like. However, it is difficult to obtain a thin and uniform surface layer by the wet coating method of the above-mentioned fluorine-containing additive-containing polymer solution on the substrate.

(C) Since a solvent is used, there is a risk of explosion and poisoning. (D) The adhesiveness between the fluorine-containing additive-containing surface layer and the substrate is not sufficient, and the fluorine-containing surface layer is likely to peel off from the substrate during use. (E) The surface layer containing the fluorine-based additive is dissolved and lost during use and its function is deteriorated. A low temperature plasma polymerization method is known as a method for solving the above-mentioned drawbacks of the prior art in which a surface layer containing a fluorine-containing additive is provided on a substrate by a wet process, which is a vacuum of 0.01 to 10 Torr. A discharge plasma of a carrier gas such as N ₂ , Ar, He or the like is mixed with a monomer organic gas below, and a plasma polymerized film is formed on the surface of the substrate by contacting the mixed gas with the surface of the substrate to be treated. It is what makes me. The formation of this polymerized film is described by JL Vossen and W. Kern in “Thin Film Proc.
esses "Academic Press, New York (1978) No. 365
CAP diagram on page (Competitive Ablation and Polymer
Phenomenon shown in the
merization) and deletion (Ablation) are considered to be due to the race reaction.

However, the above-mentioned plasma polymerization method is an extremely effective method for forming a polymerized film of nitrogen, silicon and a compound having an unsaturated bond on the surface of a substrate. There is a drawback that it is difficult to form a polymerized film of a fluorine compound on a substrate. In order to solve the above-mentioned drawbacks of the plasma polymerization method, for example, (i) H ₂ gas or silicon element is added to the reaction system. ₂ gas is added, (ii) a reactive fluorine compound having a carbon-carbon double bond such as tetrafluoroethylene is used as a monomer raw material, (iii) a polymer in which H ₂ appears such as polyethylene or polypropylene as a base material A fluorine-containing surface layer has been formed on a substrate by a plasma discharge method such as (E. Kay, IUPAC Synposium on plasma C
hemistry, Limoges, France (1977) and T. Masuoka, H. Yas
uda, J. Polym, Sci., 20, 2633-2642 (1982)), this method achieves its purpose in that it forms a fluorine-containing surface layer on a substrate, while the H ₂ There are drawbacks such as the danger of gas explosion and the danger of explosion and poisoning of a fluorine compound having a carbon-carbon double bond.

On the other hand, when an organic polymer compound such as polyethylene or polypropylene is brought into contact with fluorine-containing plasma generated from fluorocarbons such as CF ₄ and CHF ₃ or fluorocarbon, the surface region of the organic polymer compound is exposed. A method for introducing and modifying fluorine has been proposed (JP-A-55).
-99932). In addition to the problem (iii), this method has a drawback that roughness due to etching is formed on the surface of the material to be modified.

[0007]

The object of the present invention is to improve the above-mentioned drawbacks of the prior art and to have various properties such as lubricity, water repellency, light transmission, weather resistance, antistatic property, etc. It is an object of the present invention to provide a manufacturing method capable of manufacturing a molded article having a fluorine-containing thin surface layer, which is not corroded and maintains smoothness, and which is used in various applications requiring these properties, in an extremely safe manner.

[0008]

As a result of various studies, the inventors of the present invention have recognized that they have advantages such as noncombustibility but are non-reactive, and it is difficult to form a thin layer on a substrate by conventional plasma treatment. It was thought that saturated fluorocarbon compounds such as CF ₄ and C ₂ F ₆ and sulfur fluoride compounds such as SF ₆ were surprisingly considered to have a lubricity, water repellency and light The inventors have found that a strong fluorine-containing thin layer having permeability, weather resistance, antistatic property, etc. can be formed without changing the properties of the substrate as a whole, and the present invention has been completed based on this finding.

That is, the gist of the present invention is a plasma generation system.
And the reaction gas supply path and exhaust attached to the plasma generation system
And a plasma reaction system having a channel.
Using a plasma device, a reaction gas of a saturated fluorocarbon compound or a sulfur fluoride compound is introduced into the plasma reaction system to generate microwave discharge plasma, which is then placed in the plasma reaction system.
When manufacturing a molded article having a fluorine-containing thin layer on a base material, the method for manufacturing a molded article, wherein the base material is a plasma reaction system and is arranged on the exhaust passage side to form the fluorine-containing thin layer on the base material. It is in.

As the fluorine compound used as a raw material in the production of the molded article of the present invention, any of a saturated fluorocarbon compound and a sulfur fluoride compound which are gasified at room temperature or gasified at a temperature during discharge treatment can be used. Examples thereof include CF ₄ and C ₂ F ₆ having low toxicity and nonflammability, and SF ₆ having nonflammability and noncorrosion.
These may be used alone or in combination, and may be diluted with an inert gas such as N ₂ , Ar, or He for the purpose of adjusting the discharge voltage.

The substrate used in the production of the molded article of the present invention includes natural polymers, synthetic polymers and ceramics, which may be used alone or in a mixture. Examples of the natural polymer include cotton, hemp, silk, and wood, and examples of the synthetic polymer include nylon, polyester, polycarbonate, polyacetal, polysulfone, polyether sulfone, polyester ether ketone, polyacrylate, and polyimide. , Polyaramid, polyvinyl alcohol, polyurethane, polymethacrylate, polycellulose, polyepoxide,
Examples thereof include polyvinyl chloride, and further ceramics include silicate glass, quartz glass, glasses such as borate glass and phosphate glass, alumina cement,
Cement such as Portland cement and magnesia cement, porcelain such as zircon porcelain, alumina porcelain and titanium porcelain and the like, and other inorganic substances such as copper, aluminum, iron, nickel and indium,
Examples thereof include oxides, amorphous materials and alloys. These may be used alone or as a mixture, and may have any shape such as fibrous shape, plate shape, sheet shape, block shape and the like.

[0012]

Microwave discharge plasma used in the present invention
As shown in FIG. 3, the apparatus is basically constituted by a plasma generation system (magnetron) 1, a waveguide 8, a plasma reaction system 2, a raw material, a carrier gas supply path 3 and an exhaust path 4, and the reaction system 2 Alumina tubes 6 and 6'are arranged inside the substrate, and the substrate 7 to be plasma-treated is arranged on the exhaust passage 4 side downstream from the plasma generation region. Preferred
The base material 7 is arranged downstream of the alumina tubes 6, 6 '.
By arranging the base material in this way, the etchant does not reach the base material, and only neutral radicals having a long life can reach the base material 7.

As a microwave plasma generation method used in the present invention, a microwave plasma is generated by a waveguide type method.
This is a method of generating plasma and causing a reaction to form a thin layer .

The thickness of the surface thin layer to be formed can be arbitrarily changed according to the intended use of the molded product. For example, a layer thickness of 0.001 to 10 .mu. To be done. When productivity of films, sheets and the like is required, continuous production is possible with a thickness of 0.001 to 0.1 μm.

[0016]

The present invention will be further described with reference to the following examples, but the present invention is not limited to these examples. Comparative Example 1 (1) Using a commercially available polyethylene terephthalate film (hereinafter abbreviated as PET film) as a substrate, CF ₄ as a raw material gas, and a plasma discharge device by high frequency discharge shown in FIG. 2 as a plasma discharge device, The PET film was plasma discharge treated.

The plasma discharge device shown in FIG. 2 includes a plasma generation system (high frequency power supply) 1, a plasma reaction system 2, raw materials,
The plasma reaction system 2 is basically composed of a carrier gas supply path 3 and an exhaust path 4, and a pair of aluminum electrodes 5 and 5'are arranged in the plasma reaction system 2 with a distance of 1.5 cm therebetween. A circular PET film 7 having a diameter of 3.2 cm, which was a processed product, was set.

CF ₄ as a raw material gas is introduced into the plasma reaction system 2 at a flow rate of 5 to 50 cm ³ / min under a pressure of 1 to 4 Torr through the raw material and the carrier gas supply passage 3 to obtain 50 W. A high frequency power of 13.56 MHz is applied to the electrodes 5 and 5'to generate a discharge, and a level of 0.25 to 30
A plasma discharge treatment was performed for a minute to form a thin surface layer on the PET film. The temperature of the PET film during discharge was not particularly controlled, but was kept below the glass transition point (69 ° C.).

(2) The ESCA spectrum (X-ray photoelectron spectrum) of the thin surface layer of the obtained plasma discharge treated PET film was measured, and as a result, formation of —CF ₂ — bond derived from fluorination of the benzene ring was observed. , = CF
Since no bond formation was observed, it is inferred that this skin layer has the structure:

[0020]

[Chemical 1]

[0021]

[Chemical 2]

The thickness of this thin surface layer was about 0.002 μm by ESCA analysis. (3) Next, changes in the contact angle of water drop (θ) as a function of the plasma discharge treatment time (t) are shown in a, b and c in FIG. In this figure, one dot (dot) means the average value of 3 to 4 measurements. The contact angle of the untreated PET film was 70 ° (t = 0 min), which was in agreement with literature values. From a, b, and c shown in FIG. 1, it was confirmed that the contact angle depended on the treatment time even when the raw material gas flow rate and pressure were varied, and the contact angle rapidly increased when the discharge treatment started. It reached 100-110 ° in 20 minutes and became constant thereafter.

Polytetrafluoroethylene (PTFE)
Has a contact angle of 108 °, the contact angle is 10 to 2 in this example.
It was found that the surface of the PET film treated with CF ₄ plasma discharge for 0 minutes had a hydrophobic property equivalent to that of PTFE.
In addition, it was confirmed that the measured results after about 24 hours after the treatment and the measured results after about 2 months of the same sample retained the same value within the error.

(4) Further, the surface roughness of the surface thin layer of the plasma discharge treated PET film was observed using a scanning electron microscope (SEM). As a result, this surface thin layer was found to be untreated PE.
It was found to have a uniform roughness due to etching compared to the T film. Example 1 (1) PET film as a base material and C as a raw material gas
The PET film was subjected to plasma discharge treatment by using the plasma discharge device by microwave discharge shown in FIG. 3 as the plasma discharge device of F ₄ .

The plasma discharge device shown in FIG. 3 is basically composed of a plasma generation system (magnetron) 1, a plasma reaction system 2, a raw material, a carrier gas supply passage 3 and an exhaust passage 4, and is provided inside the reaction system 2. Alumina tubes 6 and 6 ′ were arranged, and a rectangular (4.5 × 2.5 cm) PET film 7 as an object to be treated was set on the inner wall. CF ₄ which is a raw material gas is introduced into the plasma reaction system 2 under the same conditions as in Comparative Example 1 through the raw material and the carrier gas supply passage 3, and 160 W
With a microwave discharge of 2450 MHz at
Zuma was generated and plasma discharge treatment was performed for 0.25 to 30 minutes to form a thin surface layer on the PET film. Although the temperature of the PET film during discharge was not particularly controlled,
The temperature was kept below the glass transition point (69 ° C.).

(2) As a result of measuring the ESCA spectrum of the surface thin layer of the obtained plasma discharge PET film, it was confirmed that it had the same structure as the surface thin layer of the plasma discharge PET film obtained in Comparative Example 1. It was (3) Next, the change in the contact angle of water droplet (θ) as a function of the plasma discharge treatment time (t) is shown in d in FIG. In this figure, one point (dot) means the average value of 3 to 4 measurements. From d shown in FIG. 1, the contact angle rapidly increased when the discharge treatment started, reached about 105 ° in 20 minutes, and became constant thereafter. Therefore, in this example, CF _{4 for} 20 minutes
The surface of the PET film treated with plasma discharge is PTFE
It was found to have a hydrophobicity equivalent to that of In addition, it was confirmed that the measurement results after about 24 hours after the treatment and the measurement results after about 2 months of the sample also kept the same value within the error.

(4) Further, the surface roughness of the surface thin film layer of the plasma discharge treated PET film was observed using a scanning electron microscope (SEM).
It has been found that it has the same smoothness as the T film, and in this respect is different from the surface thin layer of the plasma discharge treated PET film of Comparative Example 1 having a uniform roughness. Comparative Example 2 (1) PET film as a base material and SF ₆ as a raw material
Was subjected to plasma discharge treatment using the same plasma discharge device as in Comparative Example 1.

The raw material SF ₆ is added to 1-2 torr (Tor).
Inert gas He at a flow rate of 10 SCC / min under the pressure of r)
With plasma reaction system 2 and 1 at 30W level
A high frequency power of 3.56 MHz was applied to the electrodes to cause discharge, and plasma discharge was performed for 1 to 30 minutes to form a thin layer on the PET film. (2) The change in the contact angle of water drop (θ) as a function of the plasma discharge treatment time (t) is shown in e in FIG. In this figure, one point (dot) means the average value of 3 to 4 measurements. From e shown in FIG. 1, the contact angle rapidly increased when the discharge treatment started, reached about 108 ° in 20 minutes, and became constant thereafter. Therefore, in this example, SF _{6 for} 20 minutes
The surface of the PET film treated by plasma discharge is PTF
It was found to have the same hydrophobicity as E.

[0029]

Industrial Applicability The method for producing a molded article having a fluorine-containing thin surface layer of the present invention is a saturated fluorocarbon compound having low toxicity and nonflammability or a fluorocarbon compound having nonflammability and noncorrosion during production. Since a sulfur fluoride compound is used, there is an advantage that it is safe with less danger of explosion and the like as compared with the conventional plasma discharge treatment.

Further, the molded article having the fluorine-containing thin surface layer of the present invention has properties such as lubricity, water repellency, light transmittance, weather resistance and antistatic property, and in particular, it is subjected to microwave plasma treatment. It has excellent smoothness and is preferably used in the following applications. (A) Magnetic tapes, magnetic disks, which require lubricity,
Optical recording disks, magnetic tape leader tapes, trailer tapes, sliding parts for precision equipment such as cameras and watches, sliding members such as ceramic artificial bone joints, or polymeric polymer release materials, etc. (b) Water repellency is required Waterproof map information film, moisture-proof film for chemicals and precision instruments, fishnets, window materials for vehicles including sunroofs, window materials for high-rise buildings, roof tiles, rain gear such as umbrellas, packaging packages, etc. ( C) Agricultural film for plant cultivation that requires light transmission, film for solar collectors or infrared absorption cells, etc. (d) Light weight that requires weather resistance and outdoor roof that is effective in reducing daytime lighting costs wood, etc., (e) dustproof wall materials that require antistatic properties, photographic plate making films, dustproof clothing, records, etc., (d) other vascular prostheses, artificial organs, medical materials such as blood back Oxygen, porous material or the like for high separation of hydrogen or the like.

[Brief description of drawings]

FIG. 1 is a plasma-treated film of the present invention and Comparative Example 1
3 is a graph showing the relationship between the water drop contact angle and the treatment time of the plasma-treated film of FIG.

FIG. 2 is a schematic view of a plasma discharge device by microwave discharge used in manufacturing a molded article of a conventional example.

FIG. 3 is a schematic view of a plasma discharge device by microwave discharge used in the production of the molded product of the present invention.

[Explanation of symbols]

 1 ... Plasma generation system 2 ... Plasma reaction system 3 ... Supply path 4 ... Exhaust path 7 ... Base material

Claims (6)

[Claims] 1. A plasma generating system and a plasma generating system
Plasma reactor with attached reaction gas supply passage and exhaust passage
And a reaction gas of a saturated fluorocarbon compound or a sulfur fluoride compound is introduced into the plasma reaction system to generate a microwave discharge plasma, and the reaction gas is placed in the plasma reaction system. that the manufacture of molded articles having a fluorine-containing thin layer on a substrate, said substrate comprising said plasma reaction system, a molded article having a fluorine-containing skin layer, characterized in that arranged in the exhaust path side Manufacturing method. 2. The saturated fluorocarbon compound is CF ₄ or C ₂ F.
_The method for producing a molded article according to claim 1, wherein the method is 6. 3. The method for producing a molded article according to claim 1, wherein the sulfur fluoride compound is SF ₆ . 4. The method for producing a molded article according to claim 1, wherein the base material is one kind of material selected from the group consisting of natural polymers, synthetic polymers and ceramics. 5. The method for producing a molded article according to claim 1, wherein the base material is a mixture of at least two kinds of materials selected from the group consisting of natural polymers, synthetic polymers and ceramics. 6. The method for producing a molded article according to claim 5, wherein the synthetic polymer is polyethylene terephthalate.