JPH0441179B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a surface treatment method for making the surface of a fluorine-containing polymer hydrophilic using a plasma polymerization method without impairing the excellent properties of the fluorine-containing polymer. . [Prior Art] Fluorine-containing polymers have extremely excellent water absorption resistance, oil resistance, and stain resistance, and are widely used in fields that require these properties.
Particularly in recent years, attention has been focused on such excellent water absorption resistance, oil resistance, and stain resistance, and efforts have been made to use fluorine-containing polymers as medical materials, such as materials for contact lenses and intraocular lenses. is being considered. Medical materials using fluorine-containing polymers have excellent water absorption resistance, oil resistance, and stain resistance, as described above, and therefore, lipids,
Although it is a preferable material because it is less likely to cause stains due to adsorption or absorption of biological components such as proteins, it is poorly compatible with biological fluids due to its low hydrophilicity, which often causes various problems. For example, when such a fluorine-containing polymer is used as a material for contact lenses or intraocular lenses, the fluorine-containing polymer has poor compatibility with biological fluids such as tear fluid and aqueous humor. Problems arise when wearing these lenses, such as not being able to obtain a good feeling of use. Therefore, in order to solve such problems, it is necessary to modify the surface of the fluorine-containing polymer to make it hydrophilic. As a modification method to make the surface of a polymer hydrophilic,
For example, a method of immersing a polymer in a strongly oxidizing solution, a method of photo-oxidizing the polymer by irradiating it with ultraviolet rays,
A method of treating a polymer with oxygen plasma or the like is known. However, when these methods are applied to surface treatment of fluorine-containing polymers, there is a problem that the effect of surface treatment is temporary and changes significantly over time, resulting in rapid loss of hydrophilicity over time. have. [Problems to be Solved by the Invention] The present invention solves the above-mentioned problems of conventional modification methods such as large changes over time after surface treatment, and improves the quality of fluorinated polymers. The purpose of the present invention is to provide a surface treatment method for a fluorinated polymer that imparts good hydrophilicity to the surface of the fluorinated polymer without impairing its properties, and in which the hydrophilicity does not easily change over time. do. [Means for solving the problem] In the present invention, a specific mixed gas containing a hydrocarbon compound having a double bond and oxygen is used in the presence of a substrate made of a fluorine-containing polymer to be treated. By performing plasma polymerization, a thin film made of a plasma polymer (hereinafter referred to as "plasma polymer film") is integrally formed on the surface of the substrate, thereby improving the excellent properties of the fluorine-containing polymer. The purpose is to make the surface of a substrate made of a fluorine-containing polymer hydrophilic without impairing its properties. Examples of the hydrocarbon in the present invention include compounds represented by the following general formula (A). (In the formula, R ₁ , R ₂ , R ₃ and R ₄ are the same or different and are selected from alkyl groups such as methyl, ethyl and propyl groups, alkenyl groups such as vinyl, propenyl and allyl groups, and hydrogen atoms. ) As the compound represented by the above general formula (A),
For example, ethylene, propylene, 2-butene, isobutylene, 2-methyl-2-butene, 2,3-dimethyl-2-butene, 1-butene, 3-hexene, 2-ethyl-1-butene, 3-ethyl-3 −
hexene, 3,4-diethyl-3-hexene,
1,3-butadiene, 1,3,5-hexatriene, 2-vinyl-1,3-butadiene, 3-vinyl-1,3,5-hexatriene, 3,4-divinyl-1,3,5- Hexatriene, 2-pentene, 2-methyl-1-butene, 2,3-dimethyl-2-pentene, 3-methyl-3-hexene, 3
-ethyl-2-pentene, 3-methyl-4-ethyl-3-hexene, 2-methyl-3-ethyl-2
-pentene, 2,3-dimethyl-3-hexene,
Isoprene, 1,3-pentadiene, 3-methyl-1,3-pentadiene, 4-methyl-1,3-
Pentadiene, 3,4-dimethyl-1,3-pentadiene, 3-methyl-1,3,5-hexatriene, 3-vinyl-1,3-pentadiene, 3-
Methyl-4-vinyl-1,3,5-hexatriene, 3-vinyl-4-methyl-1,3-pentadiene, 3,4-dimethyl-1,3,5-hexatriene, 1,3-hexadiene, 2-ethyl-
1,3-butadiene, 3-ethyl-1,3-hexadiene, 4-ethyl-1,3-hexadiene,
3,4-diethyl-1,3-hexadiene, 3-
Vinyl-1,3-hexadiene, 3-ethyl-
1,3,5-hexatriene, 3-ethyl-4-
Vinyl-1,3,5-hexatriene, 3,4-
Diethyl-1,3,5-hexatriene, 3-vinyl-4-ethyl-1,3-hexadiene, 3-
Methyl-1,3-hexadiene, 4-methyl-
1,3-hexadiene, 3-ethyl-1,3-pentadiene, 3-ethyl-4-methyl-1,3-
Pentadiene, 3,4-dimethyl-1,3-hexadiene, 3-methyl-4-ethyl-1,3-hexadiene, 3-ethyl-4-methyl-1,3-
hexadiene, 3-methyl-4-ethyl-1,
Examples include 3,5-hexatriene, 3-vinyl-4-methyl-1,3-hexadiene, 1,4-pentadiene, and preferably ethylene, propylene, 1,3-butadiene, 1-butene, 2-butene or isobutylene. Other examples of hydrocarbons in the present invention include cyclic hydrocarbon compounds containing double bonds. Examples of the cyclic hydrocarbon compounds containing double bonds include benzene, toluene, ethylbenzene, propylbenzene, cumene, butylbenzene, xylene, ethyltoluene, cymene, diethylbenzene, trimethylbenzene, tetramethylbenzene, styrene, methylstyrene, Allylbenzene, divinylbenzene, 1-phenyl-1,
Aromatic hydrocarbons such as 3-butadiene, biphenyl, 1,2-diphenylethane, cyclopentene, cyclopentadiene, fulvene, cyclohexene, methylcyclohexene, cyclohexadiene, cyclobutene, cyclooctatetraene, menthene, limonene, di-pentene, terpinolene, Alicyclic hydrocarbons such as terpenene, phelandrene, sylvestrene, carene, pinene, and bornene; condensed polycyclic hydrocarbons such as pentalene, indene, and naphthalene; bicyclo-(2,2,1)-2
-bridged hydrocarbons such as heptene, spiro-(4,
5) Spiro ring hydrocarbons such as -1,6-decadiene and spiro(cyclopentane-1,1'-indene) can be mentioned, and preferably benzene,
Styrene, toluene, ethylbenzene, xylene, ethyltoluene, diethylbenzene or methylstyrene. These compounds are plasma polymerizable substances that can be gasified in a plasma polymerization system. Moreover, these compounds can be used in combination. The present invention is characterized in that hydrocarbons are mixed with oxygen in plasma polymerization, and this mixed gas is used.
20 mol% of inorganic gases such as carbon dioxide, water vapor, nitrogen, argon, helium, xenon, neon, etc.
You can add the following amount. Mixing ratio of hydrocarbon and oxygen (hydrocarbon/oxygen)
is usually 0.1 to 10 in molar ratio, preferably 0.2 to 6,
More preferably, it is 0.2-4. This mixing ratio
If it is less than 0.1, the production rate of the plasma polymer film will be slow and it will be impractical, and the durability of the plasma polymer film will be poor.If it exceeds 10, the hydrophilicity of the plasma polymer film will be insufficient. At the same time, localized areas with insufficient hydrophilicity occur. As the fluorine-containing polymer used in the present invention,
For example, homopolymers and copolymers of fluorine-containing monomers such as tetrafluoroethylene, fluorovinylidene, fluoroalkyl acrylate, fluoroalkyl methacrylate, fluoroketone, fluorovinylether, tetrafluoroethylene and propylene, fluoroalkyl acrylate, or fluoroalkyl A copolymer of a fluorine-containing monomer such as methacrylate and an alkyl acrylate or an alkyl methacrylate and a non-fluorine-containing monomer, obtained by reacting a fluorine-containing tetrabasic acid dianhydride with a fluorine-containing diamine It is obtained by reacting a polymer, a fluorine-containing diisocyanate, a polyalkylene glycol, and a diamine. Examples include, but are not limited to, fluorine-containing silicone polymers such as methyltrifluoropropylsiloxane. Additionally, additives such as reinforcing agents, plasticizers, stabilizers, etc. may be added to these polymers in order to improve their properties. Furthermore, the fluorine-containing polymer used in the present invention is
polymethyl methacrylate, polycarbonate,
Fluorine-containing materials such as tetrafluoromethane, hexafluoroethane, tetrafluoroethylene, octafluoropropane, perfluoromethylcyclohexane, and perfluorotoluene are pre-applied to the surface of fluorine-free polymers such as polystyrene, polyimide, polyamide, polysiloxane, and polyethylene terephthalate. Does not contain fluorine by forming a plasma polymer film of a compound or a mixture of these or a mixture of these and a hydrocarbon such as methane, or an inorganic fluoride such as nitrogen fluoride, boron fluoride, or fluorinated silane. Polymer surfaces that have been fluorinated by plasma treatment, polymer surfaces that do not contain fluorine that have been fluorinated with fluorine gas, hydrogen fluoride, metal fluorides, etc. The surface of a polymer that does not contain fluorine may be coated with a fluorine-containing polymer. The conditions for plasma polymerization in the present invention, such as the degree of vacuum in the reaction vessel, the flow rate of the above-mentioned mixed gas, and the discharge power, are the same as those for ordinary plasma polymerization, and are not particularly limited, but for example, The degree of vacuum in the reaction vessel can be 1 millimeter to 10 Torr, and the flow rate of the mixed gas can be 0.1 to 100 cc per minute (STP) under standard conditions when the capacity of the reaction vessel is 50 mm.
In addition, the discharge power is determined when the electron temperature of the plasma is 5,000 to 8,000.
It is preferable to adjust the discharge power so that the discharge power is constant. Incidentally, the electron temperature can be measured by the method described in JP-A-54-135574. If the electron temperature is less than 5,000 degrees, the formation rate of the plasma polymer film is slow, making it impractical; if it exceeds 80,000 degrees, the hydrophilicity of the surface of the fluorine-containing polymer may become uneven depending on the location. Moreover, the durability becomes inferior.
In order to impart even higher durability to the plasma polymer film, the discharge power is adjusted so that the electron temperature is between 5,000 and 60,000 degrees. The plasma polymerization time varies depending on the thickness of the plasma polymer film to be formed on the fluorine-containing polymer. The thickness of the plasma polymer film is not particularly limited, but is usually 1 to 1.
The thickness only needs to be about 5000 Å, so the plasma polymerization time can be short, for example, several tens of minutes or less. The apparatus used for plasma polymerization is, for example, as shown in FIG. 1, a coil 2 is provided at 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 this, and a high frequency power source 3 is connected to the coil 2. A substrate S made of a fluorine-containing polymer to be treated is held on a support stand 4 in the container 1, and while the inside of the reaction container 1 is evacuated, hydrocarbons and hydrocarbons are introduced into the reaction container 1 through the gas inlet 5. A mixed gas with oxygen is introduced, and a high frequency voltage is applied to the coil 2 from the power source 3 to generate plasma in the reaction vessel 1, and this plasma is made to act on the outer surface of the substrate S made of the fluorine-containing polymer. A plasma polymer film is then formed thereon. Alternatively, as shown in FIG. 2, a pair of electrodes 11, 11' facing each other is provided in a reaction vessel 10 constituted by a bell gear, and a substrate S made of a fluorine-containing polymer to be treated is held between them. , electrode 1
For example, an AC power source 12 is connected between electrodes 11 and 11', thereby generating plasma between electrodes 11 and 11'. This plasma is applied to the outer surface of the substrate S to form thereon a plasma polymer film made of a mixed gas of hydrocarbon and oxygen. Note 13
1 is an exhaust pipe, and 14 and 14' are reaction gas introduction pipes. In addition, as an apparatus for plasma polymerization, the first
For example, the energy source for plasma generation may be either a direct current or an alternating current power source without being limited to what is shown in the figures and FIG. 2. In the case of alternating current, the frequency may be low frequency, high frequency, or microwave. In the case of microwaves, the coupling method between the amplifier and the plasma system may be either a ladder type or a cavity type. Furthermore, the type of plasma generating electrode, ie, inductive type, capacitive type, etc., is not limited at all. [Examples] Examples of the present invention will be described below, but the present invention is not limited thereto. Example 1 Using the reaction vessel shown in FIG. 2, a contact lens and a disc (thickness 1 mm, diameter 15 mm) made of methyl methacrylate-perfluoroalkylethyl methacrylate copolymer were held on a support stand,
While introducing a mixed gas of ethylene (flow rate: 10 cc (STP)/min) and oxygen (flow rate: 10 cc (STP)/min) into the reaction vessel, a vacuum level of 50 mTorr was maintained within the vessel, and the electrode was 10 KHz alternating current power was applied to generate plasma with an electron temperature of 25,000±3,000 degrees, and a reaction was caused for 10 minutes to form a plasma polymer film on the surfaces of the contact lens and disk. The contact lenses were tested on 10 samples (the same applies to the following Examples and Comparative Examples). Regarding the contact lenses having the plasma polymer film obtained above, regarding the following five items (1) to (5), and regarding the disc, regarding one item (6),
Characteristic tests were conducted. The results are shown in Table 1.
In addition, in the characteristic test of contact lenses,
Represents the number of applicable samples out of 10 samples. (1) Removal of oil and other stains: After soaking a dry contact lens in water for 5 seconds, apply cold cream to the contact lens, and place the contact lens between your thumb and index finger.
After washing with water, it was taken out into the air and the state of adhesion of water droplets was observed. As a result, those that were oil-free and well wetted with water were rated as ○, and those that retained oil and repelled water were rated as ×. (2) Hydrophilicity: After a dry contact lens was immersed in water for 5 seconds, it was taken out into the air and the state of adhesion of water droplets on the contact lens was observed. As a result, a case where the entire lens surface was well wetted with water was marked as ○, and a case where the lens surface repelled water was marked as ×. (3) Good visibility when wearing contact lenses: Evaluate whether or not visibility worsens when wearing contact lenses.
Good visibility was rated ○, and cloudy visibility was rated ×. (4) Mobility on the eyeball when wearing contact lenses: When wearing contact lenses, evaluate whether they move when blinking. Those that move moderately are rated ○, and those that are difficult to move are rated ×. (5) Surface durability: A contact lens was held between the thumb and forefinger and rubbed under water 2000 times, then taken out into the air and the state of water droplet adhesion on the contact lens was observed. As a result, a case where the entire lens surface was well wetted with water was marked as ○, and a case where the lens surface repelled water was marked as ×. (6) Changes in contact angle over time: Changes in the contact angle of water over time were measured using a disc. Comparative Example 1 Characteristic tests similar to those in Example 1 were conducted using contact lenses and discs made of methyl methacrylate-perfluoroalkylethyl methacrylate copolymer without surface treatment by plasma polymerization. The results are shown in Table 1. Example 2 In Example 1, except that the mixing ratio of ethylene and oxygen (ethylene/oxygen) was set to 4 in molar ratio,
Plasma polymerization was carried out in the same manner as in Example 1, and the surfaces of contact lenses and disks were treated. Characteristic tests similar to those in Example 1 were conducted on the obtained contact lenses and discs. The results are shown in Table 1. Comparative Example 2 First, only ethylene was used as a gas component without oxygen, and the ethylene flow rate was set to 7.5 cc (STP)/
Plasma polymerization was carried out in the same manner as in Example 1, except that the temperature was set to min, and then oxygen was used as the gas component (flow rate
The same plasma polymerization was performed again using only 10 cc (STP)/min.) to perform surface treatment on contact lenses and discs. Characteristic tests similar to those in Example 1 were conducted on the obtained contact lenses and discs. The results are shown in Table 1. Example 3 Same as Example 1 except that 1-butene was used instead of ethylene and the mixing ratio of 1-butene and oxygen (1-butene/oxygen) was set to 1.0 in molar ratio. Plasma polymerization was performed to treat the surface of contact lenses and discs. Characteristic tests similar to those in Example 1 were conducted on the obtained contact lenses and discs. The results are shown in Table 1. Example 4 Plasma polymerization was carried out in the same manner as in Example 1, except that benzene was used instead of ethylene and the molar ratio of benzene and oxygen (benzene/oxygen) was 1.0, and contact lenses and The surface of the disc was treated. Characteristic tests similar to those in Example 1 were conducted on the obtained contact lenses and discs. The results are shown in Table 1. Example 5 Using the reaction vessel shown in Figure 2, a contact lens and disc made of dimethylpolysiloxane were held on a support, and tetrafluoroethylene (flow rate 10 cc (STP)/min.) was introduced into the reaction vessel. While maintaining a vacuum of 50 milliTorr inside the container, 10KHz AC power was applied to the electrodes to generate plasma, and the reaction continued for 20 minutes, causing a film to form on the surface of the contact lens and disk. A plasma polymer film containing element was formed. Thereafter, the contact lens and disk were taken out from the reaction vessel, washed with water, dried, and then held on the support stand within the reaction vessel again to undergo surface treatment by plasma polymerization in the same manner as in Example 1. Characteristic tests similar to those in Example 1 were conducted on the obtained contact lenses and discs. The results are shown in Table 1.

【table】

〔Effect of the invention〕

According to the present invention, as is clear from the results of the above-mentioned examples, plasma treatment is performed using a specific mixed gas containing a hydrocarbon and oxygen in the presence of a substrate made of a fluorine-containing polymer to be treated. By carrying out polymerization and forming a plasma polymer film on the surface of the base material, the surface of the fluorine-containing polymer can be easily modified, and a material having the following excellent properties is provided. be able to. (1) The surface is composed of plasma polymer,
Has excellent water wettability. (2) The plasma polymer is chemically stable and its hydrophilicity does not easily decrease over time, and therefore can maintain good water wettability over a long period of time. (3) The above plasma polymer is excellent in terms of mechanical strength, abrasion resistance, etc., and therefore has excellent durability. (4) It has the properties (1) to (3) above without impairing the excellent properties of the fluorine-containing polymer, such as water absorption resistance, oil resistance, and stain resistance. As described above, the material obtained by the surface treatment method for a fluorine-containing polymer of the present invention has both the excellent properties inherently possessed by the fluorine-containing polymer and the excellent properties possessed by the plasma polymer film of the present invention. For example, it has good compatibility with biological fluids,
It can be preferably used for medical materials that particularly require conditions such as being resistant to adsorption or absorption of oily substances such as lipids in biological fluids and resistant to contamination. In addition, as a stain-proofing method for fibers, there is a known method of coating the fiber surface with a fluorine-containing polymer, but although such a method makes it difficult for dirt to penetrate into the fiber, once the dirt has adhered, it In particular, oil-based stains are difficult to remove in washing water. However, by applying the present invention subsequent to such a method and making the surface hydrophilic, stains can be easily removed, so the present invention is also effective as a method for surface treatment of fibers.

[Brief explanation of drawings]

FIGS. 1 and 2 show examples of apparatus used in the plasma polymerization method of the present invention, with FIG. 1 showing a discharge tube type and FIG. 2 a Bergier type. 1... Reaction container, 2... Coil, 3, 12...
Power supply, 4... Support stand, 5... Gas inlet, 10...
Reaction container (Berzier type), 11, 11'... Electrode, 13... Exhaust pipe, 14, 14'... Reaction gas introduction pipe.

Claims (1)

[Claims] 1. A fluorine-containing product characterized in that a thin film of a plasma polymer is formed on the surface of a fluorine-containing polymer by performing plasma polymerization using a mixed gas containing a hydrocarbon compound having a double bond and oxygen. Polymer surface treatment method.