JPH064695B2 - Plasma polymerization treatment method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a plasma polymerization treatment method, and more specifically, to a uniform thin film having excellent hydrophilicity on the surface of a substrate, which hydrophilicity does not change with time. The present invention relates to a plasma polymerization treatment method for forming.

(Prior Art) Conventionally, as a method for hydrophilizing the surface of various substrates, a method of oxidizing the surface of the substrate in oxygen plasma to hydrophilize the surface is known. However, oxygen plasma has the following drawbacks. That is, since oxygen atoms and oxygen molecules have a high electron affinity and easily become negative ions in plasma, an auto ionization phenomenon occurs. Therefore, the plasma state in the reaction vessel is not uniquely determined by the energy applied from the outside, for example, high-frequency power or microwave power, and spatially sparse and dense regions of ions are generated or they vibrate. It makes you unstable.

The surface hydrophilic treatment method using oxygen plasma makes it difficult to perform a uniform surface treatment. Further, even if the surface is made hydrophilic by oxygen plasma treatment, there is a drawback that the hydrophilicity changes with time and the hydrophilicity deteriorates with time.

As a surface hydrophilic treatment method other than the oxygen plasma treatment method, a chemical treatment method such as immersing the polymer in a highly oxidizing solution or introducing a hydrophilic functional group into the polymer molecule, and irradiating the polymer with ultraviolet rays Then, a method of performing photo-oxidation is known. However, each method has a drawback that the hydrophilicity deteriorates due to a change with time.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned drawbacks and has excellent hydrophilicity on the surface of the substrate by the plasma polymerization treatment, and the hydrophilicity does not change with time, and further oil etc. Uniform thin film with excellent dirt removability and durability (hereinafter referred to as "plasma polymerized film")
The present invention provides a surface treatment method for forming a.

(Means for Solving Problems) The present invention uses a nitro compound represented by the general formula: R—NO ₂ (wherein R represents a hydrocarbon group having 1 to 10 carbon atoms), Plasma electron temperature is 1 × 10 ⁴ −3.5 ×
The present invention provides a plasma polymerization treatment method characterized by forming a thin film on the surface of a substrate by carrying out plasma polymerization in the range of 10 ⁴ K.

Hereinafter, the present invention will be described in detail.

The nitro compound represented by R-NO _2,: Formula
Nitromethane, nitroethane, 1-nitropropane, 2
-Nitropropane, 1-nitrobutane, 2-nitrobutane, 2-methyl-1-nitropropane, 1-nitropentane, 1-nitrohexane, 2-nitrohexane, 1-
Nitropropene, 2-methyl-1-nitropropene, 1
-Saturated or unsaturated aliphatic nitro compounds such as nitrodecane, nitrocyclopentane, nitrocyclohexane,
Nitrocycloheptane, nitrocyclooctane, 1-nitrocyclooctene, (nitromethyl) cyclohexane, (nitromethyl) cyclopentane, 1-nitro-1
Saturated or unsaturated alicyclic nitro compounds such as cyclohexene, and nitrobenzene, o-nitrotoluene,
m-nitrotoluene, p-nitrotoluene, 1-nitronaphthalene, 2-nitronaphthalene, (nitromethyl)
Aroma such as benzene, o- (nitromethyl) toluene, m- (nitromethyl) toluene, p- (nitromethyl) toluene, 2-nitro-m-xylene, 4-nitro-m-xylene, 3-nitro-o-xylene. Group nitro compounds and the like can be mentioned. Among these nitro compounds, a saturated or unsaturated aliphatic nitro compound and / or a saturated or unsaturated alicyclic nitro compound are preferably used.

All of these nitro compounds are plasma-polymerizable substances that can be gasified in a plasma reaction system.

These nitro compounds can be used alone or in combination of two or more, and when used in combination of two or more,
The mixing ratio is not particularly limited.

R in the general formula: R-NO ₂ represents a hydrocarbon group having 1 to 10 carbon atoms, but when the number of carbon atoms in the hydrocarbon group is 11 or more, the hydrophilicity of the obtained plasma polymer film is Is insufficient.

In the present invention, the nitro compound is used, and examples of the compound include hydrogen, carbon monoxide, carbon dioxide, water vapor, nitrogen, carbon mononitride, carbon dinitride, ammonia, carbon disulfide, argon, helium, xenon, neon. You may mix and use gas, such as 20 mol% or less.

In the practice of the present invention, the conditions of the plasma polymerization treatment, for example, the degree of vacuum in the reaction vessel, the amount of the nitro compound used, the discharge power, etc., can be appropriately determined based on the conditions used in the usual plasma polymerization reaction. . For example, the degree of vacuum in the reaction vessel is 1 mm Torr-10 Tor.
When the volume of the reaction vessel is 50, the amount of the nitro compound used is about 0.1 to 100 cc per minute as a standard state gas volume. In the present invention, the electron temperature of the plasma in the reaction vessel is 1 × 10 ⁴ -3.5 × 10 ⁴ by adjusting the amount of the nitro compound used, the degree of vacuum in the reaction vessel, the discharge power, and other conditions. It is preferable to adjust it so that it falls within the range of K. When the electron temperature of plasma is 1 × 10 ⁴ K, the generation rate of the plasma polymer film is slow, and it is difficult to form a uniform plasma polymer film.
On the other hand, when it exceeds 3.5 × 10 ⁴ K, the hydrophilicity of the obtained plasma polymer film becomes insufficient. In particular, the electron temperature of plasma is preferably in the range of 1 × 10 ⁴ -2.5 × 10 ⁴ K, and in this range, a plasma polymer film whose hydrophilicity does not change with time can be formed. it can.

The electron temperature used in the present invention is as described in JP-A-54-135.
It is measured by the method described in Japanese Patent No. 574.

The plasma treatment time in the present invention depends on the thickness of the plasma polymer film to be formed on the substrate. The thickness of this plasma polymer film is not particularly limited, but normally, it may be about 1-5,000 Å. Therefore, the plasma polymerization treatment time can be short, for example, several tens of minutes or less.

The plasma polymerization treatment of the present invention can be carried out, for example, using an apparatus as shown in FIG. A coil 2 is provided on one end of a small diameter portion of a reaction vessel 1 connected to a vacuum pump (not shown), a high frequency power source 3 is connected to the coil 2, and a substrate S is held on a support 4 in the reaction vessel 1. The gas of the nitro compound is introduced into the reaction container 1 through the gas introduction pipe while the reaction container 1 is evacuated. A high frequency voltage is applied to the coil 2 from a power source 3 and the electron temperature is measured by a thermal probe 6 (described in JP-A-54-135574), the gas flow rate, the degree of vacuum in the reaction vessel and / or the discharge. While adjusting the electron temperature within a predetermined range by adjusting the electric power, plasma is generated in the reaction vessel 1, and the plasma is made to act on the surface of the substrate S to form the plasma polymer film by the nitro compound on the substrate S. Formed on the surface of.
It is also possible to use an apparatus composed of a bell jar as shown in FIG. Reaction vessel 10
A pair of electrodes 11 and 11 'facing each other are provided inside, a substrate S is held between them, and an AC power supply 12, for example, is connected between the electrodes 11 and 11'.
A plasma is generated between 1 '. At this time, the electron temperature is measured by the thermal probe 15, and the electron temperature is adjusted within a predetermined range by adjusting the gas flow rate, the degree of vacuum in the reaction vessel and / or the discharge power. This plasma is caused to act on the surface of the substrate S to form a plasma polymer film on the surface of the substrate S by the nitro compound. In addition, 13 is an exhaust pipe, 1
Reference numerals 4 and 14 'are gas introduction pipes.

The apparatus for carrying out the plasma polymerization treatment of the present invention is not limited to those shown in FIGS. 1 and 2, and for example, the energy source for plasma generation is either a direct current or an alternating current power source. May be In the case of alternating current, the frequency may be any of low frequency, high frequency, and microwave. Here, in the case of microwave, the coupling method between the amplifier and the plasma system may be either a ladder type or a cavity type. Further, the type of the plasma generating electrode, that is, the induction type, the capacitance type and the like are not limited at all.

As the substrate used in the present invention, any material capable of forming a plasma polymer film can be used. For example, optical products, particularly optical products utilizing light transmission, refraction or reflection, and various Examples of the material include cell culture beds and artificial organs. Representative examples of optical products include contact lenses, intraocular lenses, spectacle lenses, camera lenses, various lenses such as flannel lenses, window glass, various flat or curved glass such as automobile window glass, prisms for single-lens reflex cameras, Examples include various prisms such as triangular prisms, various mirrors having a convex surface, a concave surface, a flat surface, and the like. Among these optical products, materials for products that use light transmission or refraction include poly (halogenated) alkyl (meth) such as polymethyl methacrylate, polycyclohexyl methacrylate, and polyperfluoroalkyl ethyl methacrylate.
Poly (dihalogenated) aryl (meth) acrylates such as acrylate, polyphenylmethacrylate, polyhalogenated phenylmethacrylate, polyallyldiglycol carbonate, polydiallylphthalate, polydiallyl compounds such as polyadamantanedialyl compounds,
Transparent organic polymers such as poly (halogenated) vinyl compounds such as polystyrene, polyhalogenated styrene, polyvinyl chloride, polyvinylidene fluoride, and polyethylene, polydiacrylate compounds, polyimide, polyamide, polyurethane, polysiloxane, and silicone. Examples thereof include inorganic polymer compounds, inorganic glass such as lead glass and quartz glass, and transparent metal oxides such as indium oxide, tin oxide and lead oxide. Further, as a material of an optical product utilizing the reflection of light, for example, a mirror surface by vapor deposition of aluminum, tin, zinc, silver, etc., a mirror surface by sputtering of aluminum, tin, zinc, silver, nickel, chromium, or nickel, There is no particular limitation as long as it has a mirror surface by plating such as chrome,
Although commonly used plastics, metals, ceramics and the like can be used, when these are used, the formation of the plasma polymer film is performed on the mirror surface.

In these optical products, in order to impart various functions to the optical surface, the optical surface may be subjected to desired treatment in advance. These treatments include, for example, coating with a transparent polymer,
Treatment with a plasma of a gas of a hydrocarbon compound, a halogenated hydrocarbon, an organic silicon compound, hydrogen, nitrogen, helium, neon, argon, xenon or a mixed gas of two or more of these can be mentioned.

Typical examples of the cell culture bed include petri dishes, micro timers, plates, fine particles used as carriers for containers such as bottles and fibers, and the like.
Examples of the material for these cell culture beds include natural polymers, synthetic resins, synthetic rubber, glass, ceramics and the like.

Representative examples of artificial organs include artificial kidneys, artificial hearts, and organs. Materials for these artificial organs include high-density polyethylene, low-density polyethylene,
Examples thereof include polypropylene, polystyrene, polyvinyl chloride, polyurethane, polyacrylonitrile, polyethylene terephthalate, nylon-6,6 and silicone rubber.

(Examples) Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.

Example 1 Using the reaction vessel (internal volume: 400 m) shown in FIG. 1,
A polystyrene plate was held as a base on the support 4. Reaction container 1 using nitroethane as the nitro compound
Gas flow rate from the gas inlet pipe 5 to 2cc (STP) / min
While introducing into the reactor, the inside of the reaction vessel was maintained at a vacuum degree of 10 milliTorr. High temperature power 13.56MHz is applied to the coil 2 and the discharge power is adjusted to adjust the electron temperature (2.2 ± 0.2) ×
Plasma of 10 ⁴ K was generated and plasma polymerization treatment was performed for 10 minutes to form a plasma polymer film on the surface of the polystyrene plate.

The contact angle of water on the surface of the obtained polystyrene plate was measured by the droplet method. Further, the contact angle of this water was measured every predetermined time, and the change with time was examined. The results are shown in Table 1.

Also, the thickness of the plasma polymer film formed on the surface of the polystyrene plate is such that a silicon wafer is placed next to the polystyrene plate and plasma polymerization processing is performed to form a plasma polymer film on the wafer at the same time. Ellipsometer (trade name, GAER)
It was determined by measurement using a TNER ellipsometer L117 type), and the result was 650 ± 100A.

Example 2 Obtained by performing plasma polymerization treatment in the same manner as in Example 1 except that 1-nitropropane was used as the nitro compound and the electron temperature was (1.9 ± 0.2) × 10 ⁴ K. The contact angle of water and the change with time of the contact angle of the plasma polymer film were determined, and the results are shown in Table 1.

Example 3 A plasma polymer obtained by performing plasma polymerization treatment in the same manner as in Example 1 except that nitrobenzene was used as the nitro compound and the power temperature was (1.3 ± 0.2) × 10 ⁴ K. The contact angle of water and the change with time of the contact angle of the film were determined. The results are shown in Table 1.

Comparative Example 1 With respect to the same substrate as in Example 1 which was not subjected to the plasma polymerization treatment, the contact angle of water and the change with time of the contact angle were determined. The results are shown in Table 1.

Example 4 A plasma polymerization treatment was carried out in the same manner as in Example 1 except that 1-nitro-1 cyclohexene was used as the nitro compound and the power temperature was (1.6 ± 0.2) × 10 ⁴ K. The contact angle of water and the change with time of the contact angle of the obtained plasma polymer film were determined. The results are shown in Table 1.

Example 5 A 1/1 (molar ratio) mixed gas of nitroethane and nitromethane was used as the nitro compound, and the power temperature was set to (2.1
The plasma polymerization treatment was performed in the same manner as in Example 1 except that the value was ± 0.2) × 10 ⁴ K, and the contact angle of water and the change with time in the contact angle of the obtained plasma polymer film were determined.
The results are shown in Table 1.

Example 6 Plasma polymerization treatment was performed in the same manner as in Example 1 except that a glass plate was used as the substrate, and the contact angle of water and the change with time of the contact angle of the obtained plasma polymer film were determined.
The results are shown in Table 1.

Comparative Example 2 Plasma polymerization treatment was carried out in the same manner as in Example 1 except that high frequency power was applied so that the power temperature of the plasma was (4.0 ± 0.3) × 10 ⁴ K, and the obtained plasma weight was obtained. The contact angle of water and the change with time of the contact angle of the united film were determined. The results are shown in Table 1.

Comparative Example 3 A plasma polymerization treatment was carried out in the same manner as in Example 1 except that high frequency power was applied so that the power temperature of the plasma was (0.6 ± 0.2) × 10 ⁴ K. The contact angle of water and the change with time of the contact angle of the united film were determined. The results are shown in Table 1.

Comparative Example 4 Plasma polymerization treatment was performed in the same manner as in Example 1 except that triethylamine was used as a compound to be introduced into the reaction vessel and the power temperature was (2.5 ± 0.2) × 10 ⁴ K.
The contact angle of water and the change with time of the contact angle of the obtained plasma polymer film were determined. The results are shown in Table 1.

Comparative Example 5 Obtained by performing plasma polymerization treatment in the same manner as in Example 1 except that 1-nitrododecane was used as the nitro compound and the power temperature was (1.3 ± 0.2) × 10 ⁴ K. The contact angle of Mizuno and the change with time of the contact angle of the plasma polymer film were determined. The results are shown in Table 1.

Example 7 Plasma polymerization treatment was performed in the same manner as in Example 1 on a contact lens obtained by cutting from polymethylmethacrylate and a slice plate having a thickness of 0.4 mm and a diameter of 13 mm.

Then, each of the 10 plasma polymerization treated contact lenses and the sliced plate were tested for the following 6 items. The results are shown in Table 2.

Test 1: Removal of dirt such as oil After immersing the dried contact lens in water for 5 seconds,
Cold cream was applied to a contact lens, the contact lens was sandwiched between the thumb and forefinger, washed with water, and then taken out into the air to observe the state of water droplet adhesion. As a result, ○ those that are not oily and wet well with water
The one in which oil remained and the water was repelled was designated as x.

Test 2: Hydrophilicity The dried contact lens was immersed in water for 5 seconds and then taken out into the air, and the contact state of water droplets on the contact lens was observed. As a result, the case where the entire lens surface was well wetted with water was evaluated as ○, and the case where the lens surface repelled water was evaluated as ×.

Test 3: Good Visibility When Wearing It was evaluated whether the visibility deteriorates when the contact lens is worn, and a good visibility was evaluated as ◯, and a cloudy one was evaluated as x.

Test 4: Mobility on eyeball when worn When the contact lens was worn, it was evaluated whether or not it moved by blinking.

Test 5: Durability of the surface Place the contact lens between your thumb and index finger, and
After rubbing 000 times, it was taken out into the air and the state of water droplets adhering to the contact lens was observed. As a result, the case where the entire lens surface was well wetted with water was evaluated as ○, and the case where the lens surface repelled water was evaluated as ×.

Test 6: Change with time of contact angle The slice plate was left in the air, and the change with time of the contact angle of water was measured for this slice plate.

Comparative Example 6 The same test as in Example 7 was carried out except that the plasma polymerization treatment was not performed, and the results are shown in Table 2.

Example 8 Acrylic acid 300 m, n-butyl methacrylate 28
0m, ethylene glycol dimethacrylate 30m
, 6 mg of benzoin were polymerized, the obtained polymer was cut into a contact lens shape and a slice shape, and an esterification reaction was performed in n-butyl alcohol to soften the contact lens and slice plate. Was manufactured. The contact lens and the slice plate having a thickness of 0.4 mm and a diameter of 13 mm were subjected to plasma polymerization treatment in the same manner as in Example 1.

Then, 10 pieces of each of the plasma-polymerized contact lenses and the slice plate were tested in the same manner as in Test 1 to Test 6 of Example 7. The results are shown in Table 2.

Comparative Example 7 The same test as in Example 8 was carried out except that the plasma polymerization treatment was not performed, and the results are shown in Table 2.

Example 9 Ten polystyrene petri dishes were subjected to plasma polymerization treatment in the same manner as in Example 1.

After storing the above 10 petri dishes in the air for 24 hours, 2
The Chinese hamster lung-derived cell line V-79, which had been subjected to high-temperature sterilization treatment for 4 hours and was separately cultivated, was inoculated into each dish as free cells with a 0.25 wt% trypsin solution, and contained 10 wt% fetal bovine serum. Eagle M
Using EM medium (manufactured by Nissui Pharmaceutical Co., Ltd.), carbon dioxide gas 5% by volume,
Cell culture was performed at a temperature of 37 ° C. in an incubator in an atmosphere of 95% by volume of air.

When the culture time reached 120 minutes, each petri dish was taken out of the incubator, the medium was removed, and the dish was washed with phosphate buffered normal saline, and then the pronase EDTA solution 1m was added.
Was added to each dish to release the cells adhering to the surface of the culture bed, and the number of cells was measured using a hemocytometer. Then, the ratio of the number of adhered cells to the total number of cells (adhesion rate) was determined. The results are shown in Table 3.

Comparative Example 8 The same test as in Example 9 was carried out except that the plasma polymerization treatment was not performed, and the results are shown in Table 3.

(Effects of the Invention) The plasma polymer film obtained by the plasma polymerization treatment method of the present invention is (1) excellent in hydrophilicity, and its hydrophilicity does not change with time, (2) stains such as oil adhere (3) Various lenses such as contact lenses, various prisms and various mirrors can be suitably used for surface treatment of optical products.

(4) The plasma polymerization method of the present invention is extremely useful industrially because it has excellent compatibility with biological substances such as cells and can be suitably used for surface treatment of cell culture beds and artificial organs. is there.

[Brief description of drawings]

1 and 2 show an example of an apparatus used in the plasma polymerization treatment method of the present invention. FIG. 1 shows a discharge tube type and FIG. 2 shows a bell jar type. 1. ． ． Reaction vessel (discharge tube type), 2. ． ． coil,
3,12. ． ． Power supply, 4. ． ． Pedestal, 5. ． ． Gas inlet pipe, 6, 15. ． ． Thermal probe, 10. ． ． Reaction vessel (bell jar type), 11, 11 '. ． ． Electrodes, 13. ． ． Exhaust pipe, 14, 14 '. ． ． Gas inlet pipe

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location G02B 1/10 Z 7132-2K 5/04 Z 9224-2K 5/08 Z 9224-2K G02C 7 / 04

Claims (2)

[Claims] 1. A nitro compound represented by the general formula: R—NO ₂ (wherein R represents a hydrocarbon group having 1 to 10 carbon atoms), and the electron temperature of plasma is 1 × 10 ⁴ −. 3.5 x
A plasma polymerization treatment method characterized by forming a thin film on the surface of a substrate by performing plasma polymerization in the range of 10 ⁴ K. 2. The plasma polymerization treatment method according to claim 1, wherein the substrate is an optical product, a cell culture bed or an artificial organ.