Method and apparatus for modifying fluoropolymer resin

Abstract

An improved method for modifying a fluoropolymer and a modification apparatus are provided. The method for modifying a fluoropolymer comprises a first process of irradiating ultraviolet light having an intensity in a wavelength range of at least 205 nm or less onto a first fluid containing an organic compound containing at least one of an oxygen atom and a nitrogen atom, and bringing the first fluid irradiated with ultraviolet light into contact with a fluoropolymer; and a second process of irradiating the ultraviolet light onto a second fluid containing gas or mist-like water, and bringing the second fluid irradiated with ultraviolet light into contact with the fluoropolymer. The modification apparatus comprises at least one fluid supply port for supplying a first fluid containing an organic compound containing at least one of an oxygen atom and a nitrogen atom, and a second fluid containing gas or mist-like water into a chamber, and a light source for irradiating ultraviolet light having an intensity in a wavelength range of at least 205 nm or less toward the first fluid and the second fluid within the chamber.

Description

Technology Field

[0001] The present invention relates to a method for modifying fluoropolymer resin and a modification apparatus. Background Technology

[0002] A method for modifying hydrophobic fluoropolymer resins into hydrophilic ones has been known for some time.

[0003] Patent Document 1 describes a method of contacting a substrate (91) made of fluoropolymer resin with the liquid surface of an aqueous ethanol solution (90), and irradiating the main surface (92) of the substrate (91) in contact with the aqueous ethanol solution (90) with ultraviolet light from an ArF excimer laser to modify the main surface (92) to be hydrophilic (see FIG. 10). Prior art literature

[0004] Japanese Patent Publication No. Hei 6-279590 The problem to be solved

[0005] Patent Document 1 discloses two methods for irradiating ultraviolet light onto a surface (92). As shown in FIG. 10, the first method is to place a light source (95a) above a container (93) that holds an aqueous ethanol solution (90), and to irradiate ultraviolet light (L8) onto the surface (92) by passing through the substrate (91) from the back side of the substrate (91). The second method is to place a light source (95b) below the container (93) and to irradiate ultraviolet light (L9) onto the surface (92) through the container (93) and the aqueous ethanol solution (90).

[0006] When adopting the first method, since ultraviolet light (L8) passes through the substrate (91), only thin substrates can be processed, and even if the substrate is thin, the ultraviolet light (L8) is absorbed by the substrate (91), so there is a problem that the amount of ultraviolet light (L8) reaching the main surface (92) is reduced, and the fluoropolymer resin constituting the substrate (91) is degraded by the ultraviolet light (L8). When adopting the second method, when ultraviolet light (L9) passes through the container (93) and the ethanol aqueous solution (90), the ultraviolet light (L9) is absorbed by the ethanol aqueous solution (90) or scattered by the ethanol aqueous solution (90), so there is a problem that the amount of ultraviolet light (L9) reaching the main surface (92) is reduced significantly.

[0007] Based on these problems, the purpose is to provide an improved method for modifying fluoropolymer resin and a modification apparatus. means of solving the problem

[0008] The method for modifying a fluoropolymer according to the present invention comprises: a first process of irradiating a first fluid containing an organic compound containing at least one of an oxygen atom and a nitrogen atom with ultraviolet light having an intensity in a wavelength range of at least 205 nm or less, and contacting the first fluid irradiated with ultraviolet light with a fluoropolymer; and

[0009] A second process is provided in which ultraviolet light is irradiated onto a second fluid containing gas or mist-like water, and the second fluid irradiated with ultraviolet light is brought into contact with a fluoropolymer resin.

[0010] In the present invention, ultraviolet light having an intensity in a wavelength range of at least 205 nm or less is used for the radicalization of an organic compound containing at least one of an oxygen atom and a nitrogen atom in the first process, and for the radicalization of a gas or mist-like water in the second process.

[0011] The terms used in this specification are explained. "Radical" refers to an atom or molecule having an unpaired electron. As will be described in detail later, radicals have high reactivity with other molecules because they have unpaired electrons. "Radicalization" refers to the generation of a radical from a radical source. "Organic compound containing at least one of an oxygen atom and a nitrogen atom" indicates that the molecular structure of the organic compound contains at least one oxygen atom or a nitrogen atom.

[0012] The first fluid comprises an organic compound containing at least one of an oxygen atom and a nitrogen atom. The organic compound exists in the first fluid as a gas, liquid, or mist. In the first process, the organic compound containing at least one of an oxygen atom and a nitrogen atom is radicalized by the ultraviolet light. The radicals obtained from the organic compound containing at least one of an oxygen atom and a nitrogen atom hydrophilize the surface of the hydrophobic fluoropolymer resin. In the second process, water molecules (H2O) contained in the second fluid are radicalized by the ultraviolet light to generate OH radicals and hydrogen radicals. The generated OH radicals and hydrogen radicals hydrophilize the surface layer of the fluoropolymer resin. The "surface layer" includes the surface of the object and the area near the surface within the interior of the object.

[0013] In the present invention, ultraviolet light is used for the radicalization of the first fluid and the second fluid, and the generated radicals are used for the hydrophilization of the fluoropolymer surface layer. In Patent Document 1, ultraviolet light from an ArF excimer laser is irradiated onto an aqueous ethanol solution, but the purpose of irradiating ultraviolet light in Patent Document 1 is the radicalization of ethanol molecules in the aqueous ethanol solution, not the radicalization of water molecules in the aqueous ethanol solution. In this respect, the present invention is significantly different from Patent Document 1.

[0014] In the second process, the target subjected to the ultraviolet light is a second fluid comprising gaseous or misty water. The expression "second fluid comprising gaseous or misty water" implies that the second fluid has H2O in a gaseous state (i.e., water vapor), or, even if in a liquid state, has H2O in a state in which the liquid consists of particles capable of being suspended within the fluid. Since the attenuation of ultraviolet light passing through the gaseous or misty second fluid is less than the attenuation of ultraviolet light passing through water contained in a container, more ultraviolet light can be irradiated onto the fluoropolymer resin. Consequently, hydrophilization can be promoted more effectively than in the conventional method.

[0015] Hydrophilization of the surface of a fluoropolymer refers to a treatment that increases the affinity of the surface with water molecules. If fluorine atoms on the surface of a fluoropolymer are replaced with polar functional groups that do not contain fluorine atoms, the hydrophilicity of the fluoropolymer surface is increased. As will be described in detail later, if the fluoropolymer is modified from hydrophobic to hydrophilic, for example, the fluoropolymer can be strongly bonded to other materials.

[0016] It is acceptable to perform the second process after the first process, or to perform the first and second processes in parallel. As one method of performing the first and second processes in parallel, the ultraviolet light is irradiated onto a gaseous or misty mixed fluid, which is a mixture of a first fluid in the form of a gas or mist and a second fluid in the form of a gas or mist. Although details will be described later, when ultraviolet light is irradiated onto the mixed fluid, the organic compounds in the first fluid and the water molecules in the second fluid are radicalized in parallel, and the surface layer of the fluoropolymer (i.e., the surface and the interior near the surface) becomes hydrophilic. Hydrophilization extending not only to the surface but also to the interior near the surface improves adhesion strength. Furthermore, processing multiple processes in parallel shortens the processing time and simplifies the apparatus and system. Additionally, when performing the second process after the first process, it is acceptable for the first fluid to contain organic compounds existing as a liquid.

[0017] At least one of the first process and the second process may be performed by irradiating ultraviolet light toward the fluid in contact with the fluoropolymer. To irradiate ultraviolet light toward the fluid in contact with the fluoropolymer, for example, the ultraviolet light is irradiated from the light source toward the fluoropolymer while the distance between the light source emitting the ultraviolet light and the fluoropolymer is brought close, and the fluid is flowed through the said distance. As a result, the fluid present near the surface of the fluoropolymer or inside the fluoropolymer, which is required for the modification treatment, can be radicalized. Consequently, a large number of radicals can be brought into contact with the fluoropolymer.

[0018] The above organic compound may include at least one of a hydroxyl group, a carbonyl group, and an ether bond. Since a functional group including at least one of a hydroxyl group, a carbonyl group, and an ether bond can be formed on the surface of the fluoropolymer, strong hydrophilicity can be imparted to the surface of the fluoropolymer.

[0019] The above organic compound may include at least one selected from the group consisting of alcohols, ketones, aldehydes, carboxylic acids, and phenols.

[0020] The above organic compound may include at least one selected from the group consisting of alcohols having 10 or fewer carbon atoms and ketones having 10 or fewer carbon atoms.

[0021] The above organic compound may include at least one selected from the group consisting of alcohols having 2 to 4 carbon atoms and acetone. Alcohols having 2 to 4 carbon atoms and acetone have excellent ease of availability and economic efficiency. Alcohols having 2 to 4 carbon atoms have excellent safety and ease of handling. Since acetone has a high vapor pressure, it is easy to form an atmosphere of relatively high concentration.

[0022] The above organic compound may include at least one of an amino group, an imino group, or a cyano group.

[0023] The above organic compound may include at least one selected from the group consisting of amines having 4 or fewer carbon atoms and nitriles having 4 or fewer carbon atoms. Amines having 4 or fewer carbon atoms and nitriles having 4 or fewer carbon atoms are excellent in terms of ease of availability and cost-effectiveness.

[0024] The above ultraviolet light may be generated by a xenon excimer lamp.

[0025] The modification device of the present invention is,

[0026] At least one fluid supply port for supplying into a chamber a first fluid comprising an organic compound containing at least one of an oxygen atom and a nitrogen atom, and a second fluid comprising gas or mist-like water, and

[0027] A light source is provided that irradiates ultraviolet light having an intensity in a wavelength range of 205 nm or less toward the first fluid and the second fluid within the chamber, and

[0028] The surface layer of the workpiece is hydrophilized with the first fluid irradiated with the ultraviolet light and the second fluid irradiated with the ultraviolet light.

[0029] The above fluid supply port may be positioned, for example, on the wall or ceiling of the chamber. If there is only one fluid supply port, typically, said fluid supply port is connected to both the source of the first fluid and the source of the second fluid. However, the source may be an integrated source that supplies both the first fluid and the second fluid. If there is only one fluid supply port and an integrated source is used, said fluid supply port is connected to the integrated source. If there are multiple fluid supply ports, at least one fluid supply port is connected to the source of the first fluid, and the remaining fluid supply ports are connected to the source of the second fluid. Furthermore, when the fluid supply port is connected to the source, it may be connected by interposing a fluid supply path, such as piping, between the fluid supply port and the source. Effects of the invention

[0030] An improved method for modifying fluoropolymer resin and a modification apparatus can be provided. Brief explanation of the drawing

[0031] Figure 1 is a drawing showing one embodiment of a fluoropolymer modification system. Figure 2a is a diagram illustrating the modification mechanism. Figure 2b is a diagram illustrating the modification mechanism. Figure 2c is a diagram illustrating the modification mechanism. Figure 2d is a diagram illustrating the modification mechanism. Figure 3a is a diagram illustrating the modification mechanism. Figure 3b is a diagram illustrating the modification mechanism. Figure 3c is a diagram illustrating the modification mechanism. Figure 3d is a diagram illustrating the modification mechanism. FIG. 4 is a diagram illustrating a first variation of a fluid source. FIG. 5 is a diagram illustrating a second variation of a fluid source. FIG. 6 is a drawing illustrating a first modified example of a modification device. FIG. 7 is a drawing illustrating a second modified example of a modification device. Figure 8a shows the results of ATR-FTIR analysis of the surface layer of five samples. Figure 8b shows the results of ATR-FTIR analysis of the surface layer of five samples. Figure 9 is a graph showing the relationship between processing time and contact angle. FIG. 10 is a diagram illustrating a conventional method of modifying fluoropolymer resins. Specific details for implementing the invention

[0032] Embodiments are described with reference to the drawings. Furthermore, each drawing disclosed in this specification is illustrated schematically only. That is, the dimensional ratios in the drawings do not necessarily correspond to the actual dimensional ratios, and the dimensional ratios do not necessarily correspond between the drawings.

[0033] [Overview of the Reforming System]

[0034] Below, an embodiment of a fluoropolymer resin modification system and a method for modifying a fluoropolymer resin using the modification system is shown. FIG. 1 shows a fluoropolymer resin modification system. The modification system (100) comprises a modification device (20) and a fluid supply source (30) that supplies fluid to the modification device (20).

[0035] The modification device (20) comprises a light source (3) and a fluid supply port (2) connected to a fluid supply source (30). The fluid supply source (30) supplies a first fluid (F1) containing an organic compound containing at least one of an oxygen atom and a nitrogen atom, and a second fluid (F2) containing water molecules, to the chamber (5). Details of the first fluid (F1), the second fluid (F2), and the fluid supply source (30) will be described later.

[0036] The ultraviolet light (L1) emitted by the light source (3) is vacuum ultraviolet light, more specifically, ultraviolet light that exhibits intensity in a wavelength range of at least 205 nm or less. As used in this specification, "ultraviolet light that exhibits intensity in a wavelength range of at least 205 nm or less" refers to light having an emission band of 205 nm or less. Such light includes, for example, (1) light that exhibits an emission spectrum in which the peak emission wavelength exhibiting maximum intensity is 205 nm or less while exhibiting intensity in a broad wavelength band; (2) light that exhibits an emission spectrum in which one of the multiple peaks is included in a wavelength range of 205 nm or less while exhibiting an emission spectrum that exhibits multiple maximum intensities (multiple peaks); and (3) light in which the light of 205 nm or less exhibits an integrated intensity of at least 30% or more with respect to the total integrated intensity within the emission spectrum.

[0037] For example, a xenon excimer lamp is used as the light source (3). The peak emission wavelength of the xenon excimer lamp is 172 nm. The light emitted from the xenon excimer lamp is easily absorbed by a first fluid containing an organic compound containing at least one of an oxygen atom and a nitrogen atom, and a second fluid containing water in the form of gas or mist. And, many radicals are generated from the organic compound containing at least one of an oxygen atom and a nitrogen atom and water molecules, respectively.

[0038] [Work to be treated]

[0039] In the present embodiment, the workpiece (10) is an object composed entirely of fluoropolymer resin. However, the workpiece (10) may not be an object composed entirely of fluoropolymer resin. The workpiece (10) may have an area where fluoropolymer resin is exposed on at least a portion of its surface. The workpiece (10) may be a rigid plate-shaped substrate, a long flexible film, or a three-dimensional shape rather than a plate shape.

[0040] Specific examples of the workpiece (10) to be treated include medical fluoropolymer resins or high-frequency printed circuit boards. By converting the surface of the fluoropolymer resin from hydrophobic to hydrophilic, the bonding strength between the fluoropolymer resin and other materials can be increased. In the case of a printed circuit board, for example, the bonding strength between the base material (fluoropolymer resin) and the copper plating film can be increased, and as a result, the effect of making it difficult for the copper plating to peel off is expected.

[0041] [Radical generation of the first fluid by the reforming device]

[0042] The mechanism of radical generation in the first fluid by the reforming device is explained. First, the case of an organic compound containing an oxygen atom is explained. Ethanol (C2H5OH) is given as an example of an organic compound containing an oxygen atom. The chemical reaction equation for the process of generating radicals by irradiating an ethanol molecule with ultraviolet light (hν) is shown.

[0043]

[0044]

[0045]

[0046] As shown in equations (1) to (3) above, when ultraviolet light (hν) is irradiated onto an ethanol molecule, the energy of the ultraviolet light cuts the bonds between atoms constituting the ethanol molecule, generating radicals composed of carbon atoms, hydrogen atoms, and oxygen atoms (sometimes denoted as “{CHO} radicals”) and hydrogen radicals (sometimes denoted as “H·”). {CHO} radicals include radicalized C and radicalized O. Depending on which of C and O is radicalized and at which position of C is radicalized, three types of {CHO} radicals are formed as shown in equations (1) to (3) above. It cannot be said that any {CHO} radical is generated in equal proportions.

[0047] In addition, the three types of chemical reaction equations shown in equations (1) to (3) above are for a {CHO} radical having one atom with an unpaired electron. It is acceptable for a {CHO} radical having two or more atoms with unpaired electrons to be generated by irradiation with ultraviolet light.

[0048] Next, the case of organic compounds containing nitrogen atoms is described. Ethylamine (C2H5NH2) is given as an example of an organic compound containing nitrogen atoms. The chemical reaction equation for the process of generating radicals by irradiating an ethylamine molecule with ultraviolet light (hν) is shown.

[0049]

[0050]

[0051]

[0052] As shown in equations (4) to (6) above, when ultraviolet light (hν) is irradiated onto an ethylamine molecule, the energy of the ultraviolet light cuts the bonds between atoms constituting the ethylamine molecule, generating radicals composed of carbon atoms, hydrogen atoms, and nitrogen atoms (sometimes denoted as “{CHN} radicals”) and hydrogen radicals. A radical is an atom or molecule having an unpaired electron. {CHN} radicals include those in which C is radicalized and those in which N is radicalized. Depending on which of C or N is radicalized and at which position of C is radicalized, three types of {CHN} radicals are formed as shown in equations (4) to (6) above. It cannot be said that any {CHN} radical is generated in equal proportions.

[0053] In addition, the three types of chemical reaction equations shown in equations (4) to (6) above are for a {CHN} radical having one atom with an unpaired electron. It is acceptable for a {CHN} radical having two or more atoms with unpaired electrons to be generated by irradiation with ultraviolet light.

[0054] [Modification Mechanism]

[0055] Referring to FIGS. 2a to 2d, the mechanism of modification of the surface layer of a workpiece (10) by the first process and the second process is explained when the first fluid is an organic compound containing oxygen atoms. FIGS. 2a to 2d are drawings that allow for understanding the chemical structure of the surface or surface layer of the fluoropolymer resin of the workpiece (10).

[0056] FIG. 2a shows the generation of radicals immediately before the fluoropolymer (11) (here, PTFE) is modified. As shown in FIG. 2a, on the surface of the fluoropolymer (11) before surface modification, there are many fluorine atoms (F) bonded to carbon atoms (C). Near the surface of the fluoropolymer (11), there are {CHO} radicals generated from ethanol molecules and hydrogen radicals.

[0057] Fluorine atoms contained in the fluorine resin (11) are in a bonded state with carbon atoms. The bonding energy between carbon atoms and fluorine atoms is high at 485 kJ / mol, so a very large amount of energy is required to separate fluorine atoms and carbon atoms by heat or light.

[0058] Here, the electronegativity of the fluorine atom is 4.0 and the electronegativity of the hydrogen atom is 2.2, and the two are significantly different. Because of this, hydrogen radicals can approach the fluorine atom through electrostatic attraction and break the bond between the fluorine atom and the carbon atom by forming HF (hydrogen fluoride). The bond energy between the hydrogen atom and the fluorine atom is higher at 568 kJ / mol, and since HF is released from the surface of the fluorine resin as a gas, the reaction for the formation of HF proceeds irreversibly. At the location where fluorine is removed from the surface of the fluorine resin (11), a {CHO} radical or a hydrogen radical binds.

[0059] FIG. 2b shows the appearance of the fluorine resin (11) of FIG. 2a after surface modification with radicals of the first fluid. FIG. 2b illustrates a configuration where six fluorine atoms are removed, hydrogen radicals are bonded to three of the locations, and CHO radicals are bonded to the remaining three locations, but it does not matter if fluorine atoms remain on the surface. Also, the number of bonded hydrogen radicals and the number of bonded CHO radicals do not need to be the same. For example, it does not matter if CHO radicals are bonded to all the locations where fluorine atoms were removed. On the surface of the fluorine resin (11), at least some parts have functional groups composed of carbon atoms, hydrogen atoms, and oxygen atoms (hereinafter referred to as "CHO ​​functional groups").

[0060] In FIG. 2b, the {CHO} functional group shown in (a) is formed by the {CHO} radical obtained by the formula (3) combining with the fluoropolymer (11). In FIG. 2b, the {CHO} functional group shown in (b) is formed by the {CHO} radical obtained by the formula (1) combining with the fluoropolymer (11). In FIG. 2b, the {CHO} functional group shown in (c) is formed by the {CHO} radical obtained by the formula (2) combining with the fluoropolymer (11).

[0061] The {CHO} functional group combined with the fluoropolymer (11) has polarity. The {CHO} functional groups shown in (b) and (c) of FIG. 2b each have a hydroxyl group at their terminals, so they exhibit strong hydrophilicity. The {CHO} functional group shown in (a) of FIG. 2b forms an ether bond with the fluoropolymer (11), so it does not exhibit hydrophilicity as strong as the hydroxyl group, but exhibits a certain degree of hydrophilicity. Also, in FIG. 2b, for convenience of explanation, different functional groups (a), (b), and (c) are shown in an adjacent arrangement, but in reality, it does not matter if the same functional groups are adjacent to each other.

[0062] FIG. 2c shows that in the second process, water molecules contained in the second fluid come close to the surface of the fluoropolymer (11), and radicals are generated from the water molecules. As shown in FIG. 2c, when ultraviolet light is irradiated onto gaseous or misty H2O, the energy of the ultraviolet light cuts the bonds between HO in H2O, generating OH radicals (sometimes denoted as "OH·") and hydrogen radicals.

[0063] FIG. 2d shows the appearance of the surface layer of the fluoropolymer after the second process. The surface of the fluoropolymer (11) has many hydrocarbon groups. OH radicals and hydrogen radicals generated from H2O cut the CH bonds contained in the hydrocarbon groups and remove hydrogen atoms from the hydrocarbon groups. Then, as shown in FIG. 2d, OH radicals generated from H2O bond to the places where hydrogen atoms were removed. In FIG. 2d, the functional groups enclosed by the dashed circles represent the functional groups added in the second process. By performing the second process in this way, OH groups are added to the hydrocarbon groups added in the first process, and further hydrophilization of the surface of the fluoropolymer is carried out.

[0064] Additionally, if the surface of the fluoropolymer (11) is hydrophilized by the first process, as shown in FIG. 2c, water molecules can approach the surface of the fluoropolymer (11) in the second process. Some water molecules can penetrate into the interior near the surface of the fluoropolymer (11). The water molecules that penetrate into the interior of the fluoropolymer (11) are decomposed by ultraviolet light (L1) to generate hydrogen radicals and OH radicals.

[0065] Hydrogen radicals located inside near the surface of the fluoropolymer (11) cut the CF bonds located inside near the surface of the fluoropolymer, thereby removing fluorine. OH radicals bind to the location where fluorine was removed, generating an OH group (see FIG. 2d). Additionally, hydrogen atoms may be removed from the bound OH radicals to generate a CO group. The CO group is also an oxygen-based functional group that exhibits hydrophilicity. In this way, hydrophilization proceeds inside near the surface of the fluoropolymer (11). Furthermore, as shown in FIG. 2d, hydrogen radicals may bind to the location where fluorine was removed.

[0066] The above describes the mechanism for modifying the surface layer of a fluoropolymer resin by the first and second processes when the first fluid is an organic compound containing oxygen atoms. In principle, the second process proceeds after the first process. However, both the first and second processes proceed locally within the chamber over a short period of time. Therefore, in practice, the first and second processes may be performed in parallel. Details will be described later.

[0067] In addition, since the reaction of generating radicals by irradiating the gas with ultraviolet light proceeds regardless of pressure, it is not necessary to make the chamber, which is the reaction field, a reduced pressure environment. However, in order to replace the atmosphere inside the chamber (5) with a desired gas atmosphere in a short time, it is acceptable to connect a vacuum pump to the fluid outlet (6) to reduce the pressure inside the chamber (5).

[0068] Next, referring to FIGS. 3a to 3d, the modification mechanism of the surface layer of the workpiece (10) by the first and second processes when the first fluid is an organic compound containing nitrogen atoms will be explained. FIGS. 3a to 3d are drawings that allow for understanding the chemical structure of the surface or surface layer of the fluoropolymer resin of the workpiece (10). In the following, the description of parts common to the modification mechanism when the fluid is an organic compound containing oxygen atoms will be appropriately omitted.

[0069] FIG. 3a shows the generation of radicals just before the fluoropolymer resin (11) (here, PTFE) is modified. As shown in FIG. 3a, ethylamine molecules absorb ultraviolet light to generate {CHN} radicals and hydrogen radicals. Hydrogen radicals cleave CF bonds. At the site where fluorine is removed from the surface of the fluoropolymer resin (11), {CHN} radicals or hydrogen radicals bind.

[0070] FIG. 3b shows the appearance of the fluorine resin (11) of FIG. 3a after surface modification with radicals of the first fluid. FIG. 3b illustrates the appearance in which six fluorine atoms are removed, hydrogen radicals are bonded to three of them, and {CHN} radicals are bonded to the remaining three. As such, on the surface of the fluorine resin (11), at least some parts have functional groups (hereinafter referred to as “{CHN} functional groups”) consisting of carbon atoms, hydrogen atoms, and nitrogen atoms.

[0071] In FIG. 3b, the {CHN} functional group shown in (d) is formed by the {CHN} radical obtained by the formula (6) combining with the fluoropolymer (11). In FIG. 3b, the {CHN} functional group shown in (e) is formed by the {CHN} radical obtained by the formula (4) combining with the fluoropolymer (11). In FIG. 3b, the {CHN} functional group shown in (f) is formed by the {CHN} radical obtained by the formula (5) combining with the fluoropolymer (11).

[0072] FIG. 3c shows the generation of radicals of the second fluid in the second process. FIG. 3d shows the modification of the surface layer of the fluoropolymer (11) with the generated second fluid. In FIG. 3d, the functional group enclosed by the dashed circle represents the functional group added in the second process. Even when the first fluid is an organic compound containing nitrogen atoms, the hydrophilization of the surface of the fluoropolymer is further advanced by performing the second process, just as when the first fluid is an organic compound containing nitrogen atoms.

[0073] The above describes the mechanism for modifying the surface of a fluoropolymer by the first and second processes. In the sections "Radical generation of the first gas by the modification device" and "Modification mechanism," as the first fluid, ethanol (C2H5OH) was cited as an example of an organic compound containing oxygen atoms, and ethylamine (C2H5NH2) was cited as an example of an organic compound containing nitrogen atoms. However, the fluid may be used for hydrophilization in the first process if it contains an organic compound containing at least one of oxygen atoms and nitrogen atoms, without being limited to these examples.

[0074] However, the organic compound containing an oxygen atom only needs to include at least one of a hydroxyl group, a carbonyl group, and an ether bond. Since a functional group including at least one of a hydroxyl group, a carbonyl group, and an ether bond can be formed on the surface of the fluoropolymer, strong hydrophilicity can be imparted to the surface of the fluoropolymer. In particular, it only needs to include at least one selected from the group consisting of alcohols, ketones, aldehydes, carboxylic acids, and phenols. Furthermore, it is preferable to include at least one selected from the group consisting of alcohols having 10 or fewer carbon atoms and ketones having 10 or fewer carbon atoms. Among these, alcohols having 2 to 4 carbon atoms and acetone offer excellent ease of availability and economic efficiency. In particular, alcohols having 2 to 4 carbon atoms offer excellent safety and ease of handling. Additionally, because acetone has a high vapor pressure, it is easy to form an atmosphere of relatively high concentration. In addition, the organic compound containing a nitrogen atom may include at least one of an amino group, an imino group, or a cyano group, and is more preferably selected from the group consisting of an amine having 4 or fewer carbon atoms and a nitrile having 4 or fewer carbon atoms. For example, it may be methylamine, ethylamine, or acetnitrile.

[0075] [Fluid Source]

[0076] Referring to FIG. 1, the fluid supply source (30) of the present embodiment will be described. The fluid supply source (30) has a container (55) containing an aqueous ethanol solution (51) and a carrier gas supply pipe (52) that supplies a carrier gas (G1) to the aqueous ethanol solution (51) inside the container (55). By sending the carrier gas (G1) into the liquid of the aqueous ethanol solution (51), the aqueous ethanol solution (51) is evaporated by a bubbling method, thereby simultaneously extracting a first fluid (F1) containing ethanol gas and a second fluid (F2) containing water vapor, and sending them to a reforming device (20) through the fluid supply pipe (56). In this case, the reforming device (20) can perform the first process and the second process in parallel.

[0077] The carrier gas (G1) is an inert gas, for example, nitrogen gas. The fluid supply source (30) can send a mixed fluid, in which a first fluid (F1) containing the carrier gas (G1) and ethanol gas and a second fluid (F2) containing water vapor are mixed, to the reforming device (20) through the fluid supply pipe (56). Additionally, the second fluid (F2) may contain mist-like water in addition to water vapor.

[0078] The fluid supply source (30) can adjust the mixing ratio of ethanol gas, water vapor, and carrier gas (G1) in the mixed fluid in the reforming device (20) by adjusting the amount of liquid, temperature, or ethanol concentration in the ethanol aqueous solution (51). The amount of carrier gas (G1) supplied can be adjusted using a valve (54) while observing the flow meter (53). A supply pipe may be placed to supply the ethanol aqueous solution (51) to the container (55). A discharge pipe may be placed to discharge the ethanol aqueous solution (51) from the container (55). A heater may be placed to control the temperature of the ethanol aqueous solution (51) inside the container (55). The ethanol aqueous solution (51) of this embodiment is used in which an amount of anhydrous ethanol and an amount of water are mixed in a 1:1 ratio. Also, in this specification, anhydrous ethanol refers to high-concentration ethanol in which ethanol accounts for 95 vol% or more.

[0079] [Reforming device]

[0080] With reference to FIG. 1, details of the modification device (20) will be described. The modification device (20) comprises a chamber (5), a light source (3), a fluid supply port (2) for supplying a first fluid (F1) and a second fluid (F2) into the chamber (5), a fluid discharge port (6) for discharging the fluid inside the chamber (5) out of the chamber (5), and a table (15) for placing a workpiece (10). In the present embodiment, the light source (3) is placed in a light source chamber (8) positioned above the chamber (5), and the light source chamber (8) and the chamber (5) are separated by a light-transmitting material such as quartz glass.

[0081] The modification device (20) is used, for example, in the following order. A workpiece (10) is brought onto a table (15) from outside the modification device (20) using a conveying mechanism not shown. A first fluid (F1) and a second fluid (F2) are supplied into the chamber (5) from the fluid supply port (2), and the atmosphere inside the chamber (5) is replaced with the first fluid (F1) and the second fluid (F2). After the replacement is finished, the light source (3) is turned on to perform the modification process while continuing to supply the first fluid (F1) and the second fluid (F2) into the chamber (5). After the modification process is finished, the light source (3) is turned off, the supply of the first fluid (F1) and the second fluid (F2) is stopped, and the workpiece (10) is removed from the table (15) out of the chamber (5).

[0082] [Variation Example]

[0083] Various embodiments of the fluid source and the reforming device can be considered. Variations of the fluid source and the reforming device are shown.

[0084] Referring to FIG. 4, a first variation of a fluid source is described. The fluid source (31) comprises a container (65) containing an ethanol liquid (61) and a container (75) containing a liquid water (71).

[0085] A carrier gas supply pipe (62) is inserted into the liquid of the ethanol liquid (61), and a carrier gas (G1) is sent from the carrier gas supply pipe (62) to volatilize the ethanol liquid (61) by a bubbling method. As a result, a first fluid (F1) containing the carrier gas (G1) and the ethanol gas is extracted. The ethanol liquid (61) may be high-concentration ethanol and may be anhydrous ethanol. The ethanol liquid (61) may also be an aqueous ethanol solution.

[0086] A carrier gas supply pipe (72) is inserted into the liquid of water (71), and a carrier gas (G2) is sent from the carrier gas supply pipe (72) to volatilize the water (71) by a bubbling method. As a result, a second fluid (F2) containing the carrier gas (G2) and water vapor is extracted. Additionally, it does not matter whether the water (71) is heated to volatilize it, or the water (71) is stirred to volatilize it, or the water (71) is subjected to ultrasonic vibration to volatilize it. As described above, the water contained in the second fluid (F2) does not necessarily have to be water vapor, but may be mist-like water suspended within the carrier gas (G1).

[0087] The pipe (66) through which the first fluid (F1) flows and the pipe (76) through which the second fluid (F2) flows are joined at the joining section (67) and connected to the reforming device (20). Alternatively, the pipe (66) and the pipe (76) may not be joined, and the pipe (66) and the pipe (76) may be connected to the reforming device (20) separately. The carrier gas (G1) and the carrier gas (G2) may be the same gas or different gases.

[0088] By adjusting the flow rate ratio of the carrier gas (G1) and the carrier gas (G2), the mixing ratio of the first fluid (F1) and the second fluid (F2) can be adjusted. A flow rate adjustment valve for adjusting the mixing ratio of the two fluids may be placed in the junction section (67).

[0089] By not allowing the carrier gas (G2) to flow and allowing the carrier gas (G1) to flow, the second fluid (F2) can be sent to the reforming device (20) without sending the first fluid (F1). Conversely, by not allowing the carrier gas (G1) to flow and allowing the carrier gas (G2) to flow, the first fluid (F1) can be sent to the reforming device (20) without sending the second fluid (F2). Additionally, a three-way valve for switching the flow of the two fluids may be placed in the confluence section (67). The timing of supplying the first fluid (F1) and the second fluid (F2) can be offset.

[0090] Referring to FIG. 5, a second modified example of a fluid source is described. The fluid source (32) employs a direct vaporization method. The fluid source (32) is equipped with a container (85) containing an aqueous ethanol solution (81), a carrier gas supply pipe (87) through which a carrier gas (G6) flows, a vaporizer (88), a mass flow controller (83) for controlling the liquid volume of the aqueous ethanol solution (81), and a mass flow controller (84) for controlling the gas volume of the carrier gas (G6). Using the mass flow controllers (83, 84), a fixed amount of carrier gas (G6) and a fixed amount of aqueous ethanol solution (81) are supplied to the vaporizer (88). The vaporizer (88) uses the supplied carrier gas (G6) to instantly vaporize the entire amount of the supplied aqueous ethanol solution (81). Additionally, as shown in FIG. 5, the ethanol aqueous solution (81) can be discharged from the container (85) by sending a pressurized gas (G5) to the container (85) containing the ethanol aqueous solution (81). Also, in FIG. 5, the ethanol aqueous solution (81) containing the first fluid (F1) and the second fluid (F2) is supplied to the vaporizer (88), but it is also acceptable to supply the first fluid (F1) and the second fluid (F2) to the vaporizer (88) separately.

[0091] Referring to FIG. 6, a first modified example of a modification device is described. The modification device (21) has two light sources (3) arranged such that the longitudinal direction of each light source (3) faces inward from the front of the drawing. A plurality of fluid supply ports (2) for the first fluid (F1) and the second fluid (F2) are formed on the ceiling of the chamber (5) so as to process the workpiece (10) evenly. The location and number of fluid supply ports (2) can be set considering the flow of the first fluid (F1) and the second fluid (F2). Likewise, the location and number of fluid discharge ports (6) can also be set.

[0092] The light source (3) is housed in a tube (33) that extends inward from the front of the drawing. In the tube (33), at least the portion facing the workpiece (10) is made of a material that transmits ultraviolet light (L1), such as quartz glass. The space (34) between the light source (3) and the tube (33) is filled with an inert gas that is difficult to absorb ultraviolet light. In addition, it prevents deterioration of the fluid contained in the atmosphere from adhering to the surface of the light source (3), thereby preventing a decrease in the illuminance of the light source (3).

[0093] The first fluid (F1) and the second fluid (F2) may be sent into the chamber (5) simultaneously as a mixed fluid (F1+F2) as shown in FIG. 6. Alternatively, the second fluid (F2) may be sent into the chamber (5) after the first fluid (F1) has been sent into the chamber (5). In addition, the first process and the second process may be processed in different chambers.

[0094] Referring to FIG. 7, a second modified example of a modification device is described. The modification device (22) irradiates ultraviolet light (L1) from a light source (3) toward a second fluid (F2) passing through a pipe (46). As a result, the second fluid (F2) is radicalized. Then, the second fluid (F2), containing hydrogen radicals and OH radicals, is ejected from the tip (47) of the pipe (46) toward a workpiece (10) on a table (15). When hydrogen radicals and OH radicals come into contact with the surface of the fluoropolymer in the workpiece (10), a hydrophilic layer is formed on the surface of the workpiece (10).

[0095] In this embodiment, by maintaining the distance between the workpiece (10) and the tip (47) of the pipe (46) and moving the workpiece (10) and the tip (47) relative to each other, only the area requiring modification on the workpiece (10) can be selectively processed. Also, in this embodiment, it is not necessary to fill the entire processing space enclosed by a chamber, etc. with the second fluid (F2). Furthermore, the modification device (22) can be used in the same way whether the first fluid (F1) is used or a mixed fluid of the first fluid (F1) and the second fluid (F2) is used.

[0096] For the above, one embodiment of a reforming system and variations of the fluid supply source and reforming device constituting the reforming system have been described. However, the present invention is not limited to the above-described embodiments and variations, and variations may be combined or various changes or improvements may be made to the above embodiments and variations within the scope of not departing from the spirit of the present invention.

[0097] Examples

[0098] The effect of the above modification method was confirmed through ATR-FTIR analysis and contact angle measurement experiments.

[0099] [ATR-FTIR Analysis]

[0100] As workpieces (10), five PTFE (polytetrafluoroethylene) substrates manufactured by Yodogawa Hutech Co., Ltd. were prepared, and on four of them, a modification system (100) of the embodiment shown in FIG. 1 was used to perform a hydrophilization treatment on the surface layer of the workpieces (10).

[0101] The common processing conditions are as follows. A substrate was placed inside the chamber (5) at a distance of 1 mm from the light source (3). A xenon excimer lamp with a peak wavelength of 172 nm was used as the light source (3). The radiant intensity at the surface of the light source (3) was 30 mW / cm² 2 It was. Nitrogen gas was used as the carrier gas (G1), 2L (2×10⁻⁶) per minute. -3 m 3 An amount of ) was sent, and the liquid in the container (55) was vaporized by bubbling. As described later, the liquid varies depending on the sample.

[0102] Samples S1 to S5 have the following characteristics.

[0103] [Table 1]

[0104]

[0105] Sample S1 is a substrate (PTFE resin) that has not undergone modification treatment.

[0106] Sample S2 is a sample that has been irradiated with ultraviolet light for 30 seconds under an ethanol gas atmosphere. That is, it is a sample that has undergone only the first process for 30 seconds.

[0107] Sample S3 is a sample that has been irradiated with ultraviolet light for 120 seconds under an ethanol gas atmosphere. That is, it is a sample that has undergone only the first process for 120 seconds.

[0108] Sample S4 is a sample irradiated with ultraviolet light for 30 seconds under the atmosphere of a vaporized aqueous ethanol solution. That is, it is a sample in which the first and second processes were performed for 30 seconds. The aqueous ethanol solution is 10 mL (1 × 10⁻⁶). -5 m 3 ) anhydrous ethanol and 10 mL (1 × 10⁻⁶ -5 m 3It is a liquid obtained by mixing water.

[0109] Sample S5 is a sample that has been irradiated with ultraviolet light for 120 seconds under an atmosphere of a vaporized aqueous ethanol solution. That is, it is a sample in which the first and second processes have been performed for 120 seconds. The aqueous ethanol solution used in S5 is the same as the aqueous ethanol solution used in S4.

[0110] Figures 8a and 8b show the results of ATR-FTIR analysis on the surface layers of five samples. In ATR-FTIR, a crystal with a higher refractive index than the sample is placed in close contact with the sample surface, and infrared light is irradiated onto the sample from the crystal side. By measuring the total internal reflection that penetrates near the surface and is reflected, the absorption spectrum of the sample surface layer (approximately 1 μm from the surface) is obtained. In Figures 8a and 8b, the horizontal axis represents the wavenumber, and the vertical axis represents the absorbance. Higher absorbance indicates greater absorbed infrared light energy. S1 to S5 in each figure represent the absorption spectra of samples S1 to S5, respectively. A Bruker VERTEX 70v was used as the measurement device. Diamond was used as the high refractive index crystal. The angle of incidence of the infrared light was set to 45 degrees.

[0111] The OH bonds in the surface layer have a wavenumber of 3300–3400 cm -1 It exhibits strong absorption in the vicinity. The surface CH bonds have a wavenumber of 2900–3000 cm⁻¹. -1 It exhibits strong absorption in the vicinity. From Fig. 8a, it can be seen that the OH and CH bonds in the surface layer are most numerous in the order of samples S5, S4, S3, S2, and S1. The C=O bonds in the surface layer have wavenumbers of 1700–1710 cm⁻¹. -1 Strong absorption is exhibited in the vicinity. From Fig. 8b, it was found that the C=O bonds in the surface layer were most numerous in the order of samples S5, S4, S3, S2, and S1.

[0112] It was found that OH bonds, CH bonds, and C=O bonds were formed by the modification of the surface layer of the fluoropolymer resin, as they were almost non-existent in the untreated sample S1. Furthermore, it was found that the modification of the surface layer proceeded in the order of samples S5, S4, S3, and S2, and that samples S4 and S5, which underwent modification treatment under an aqueous ethanol atmosphere, showed modification of the surface layer compared to samples S2 and S3, which underwent modification treatment only under an ethanol gas atmosphere, and that samples S3 and S5, which underwent a treatment time of 120 seconds, showed modification of the surface layer compared to samples S2 and S4, which underwent a treatment time of 30 seconds.

[0113] [Measurement of Contact Angle]

[0114] Using the modification system (100) of the embodiment shown in FIG. 1, a hydrophilization treatment was performed on the surface layer of the workpiece (10). For the workpiece (10), PTFE (polytetrafluoroethylene) manufactured by Yodogawa Hutech Co., Ltd. was used. Nitrogen gas was introduced as a carrier gas (G1) into the liquid in the container (55) at a rate of 2 L (2 × 10⁻⁶) per minute. -3 m 3 The liquid in the container (55) was sent to the chamber (5), vaporized by bubbling, and supplied to the chamber (5). As described later, the liquid varies depending on the sample. A substrate was placed inside the chamber (5) at a distance of 1 mm from the light source (3). A xenon excimer lamp with a peak wavelength of 172 nm was used as the light source (3). The radiant intensity at the surface of the light source (3) was 30 mW / cm² 2 It was. Nitrogen gas was used as the carrier gas (G1), 2L (2×10⁻⁶) per minute. -3 m 3An amount of liquid was sent, and the liquid in the container (55) was vaporized by bubbling. To measure the water contact angle, a contact angle meter DMs-401 manufactured by Kyowa Interface Chemical Co., Ltd. was used. From the measurement results of the contact angle meter, the contact angle was calculated by the elliptical curve fitting method. This calculation of the contact angle was performed at each of three locations on the surface of the same workpiece (10). The average value of the water contact angles measured at the three locations was calculated, and the said average value was determined as the final water contact angle. Other measurement conditions for the water contact angle were based on JIS R 3257 “Test method for wettability of substrate glass surface”.

[0115] Figure 9 is a graph showing the relationship between the treatment time (sec) and the contact angle (deg) of the modification.

[0116] The horizontal axis represents the processing time of the workpiece (10), and the vertical axis represents the water contact angle of the surface of the workpiece (10). A lower water contact angle indicates that hydrophilization is progressing.

[0117] As shown in FIG. 9, the contact angle in the untreated state was 119 degrees, indicating high hydrophobicity. The solid line D1 is the measurement result when an aqueous ethanol solution is used as the "liquid in the container (55)" and the first fluid and the second fluid are used (i.e., when both the first process and the second process are performed). The dashed line D2 is the measurement result when an ethanol liquid (anhydrous ethanol) is used as the "liquid in the container (55)" and only the first fluid is used (i.e., when only the first process is performed). The dotted line D3 is the measurement result when water is used as the "liquid in the container (55)" and only the second fluid is used.

[0118] From FIG. 9, it was found that if both the first and second processes are performed, hydrophilization can be achieved in a shorter time compared to the case where only the first process is performed. In addition, it was found that hydrophilization cannot be achieved with only the second process, but can be achieved by combining the second process with the first process. Explanation of the symbols

[0119] 1: Chamber 2: Fluid supply port 3: Light source 5: Chamber 6: Fluid outlet 7: Tip 8: Light source chamber 10: Workpiece 11: Fluoropolymer 15: Table 20, 21, 22: Reforming device 30, 31, 32: Fluid supply source 33: Container 34: Space 46: Piping 47: Tip (of piping) 51, 81: Aqueous ethanol solution 52: Carrier gas supply pipe 53: Flow meter 54: Valve 55, 65, 75, 85: Container 56: Fluid supply pipe 61: Liquid ethanol 62: Carrier gas supply pipe 66, 76: Piping 67: Confluence 71: Water 72, 87: Carrier gas supply pipe 83, 84: Mass flow controller 88: Vaporizer 100: Reforming System F1: First Fluid F2: Second Fluid G1, G2, G6: Carrier Gas G5: Pressure Gas L1: Ultraviolet Light

Claims

Claim 1 A method for modifying a fluorine resin, characterized by comprising: a first process of irradiating a first fluid containing an organic compound containing oxygen atoms with ultraviolet light having an intensity in a wavelength range of at least 205 nm or less, and contacting the first fluid irradiated with ultraviolet light with a fluorine resin; and a second process of irradiating a second fluid containing gas or mist-like water with ultraviolet light, and contacting the second fluid irradiated with ultraviolet light with a fluorine resin. Claim 2 A modification method according to claim 1, characterized by irradiating the gaseous or misty mixed fluid, wherein the first fluid and the second fluid are mixed in the gaseous or misty form, with the ultraviolet light, and performing the first process and the second process in parallel. Claim 3 A modification method according to claim 1, characterized by performing the second process after the first process. Claim 4 A modification method according to any one of claims 1 to 3, wherein at least one of the first process and the second process is performed by irradiating the ultraviolet light toward a fluid in contact with the fluoropolymer resin. Claim 5 A modification method according to any one of claims 1 to 3, wherein the organic compound comprises at least one of a hydroxyl group, a carbonyl group, and an ether bond. Claim 6 A modification method according to claim 5, wherein the organic compound comprises at least one selected from the group consisting of alcohols, ketones, aldehydes, carboxylic acids, and phenols. Claim 7 A modification method according to claim 6, wherein the organic compound comprises at least one selected from the group consisting of alcohols having 10 or fewer carbon atoms and ketones having 10 or fewer carbon atoms. Claim 8 A modification method according to claim 7, wherein the organic compound comprises at least one selected from the group consisting of alcohols having 2 to 4 carbon atoms and acetone. Claim 9 delete Claim 10 delete Claim 11 A modification method according to any one of claims 1 to 3, characterized in that the ultraviolet light is generated by a xenon excimer lamp. Claim 12 A modification apparatus characterized by comprising at least one fluid supply port for supplying a first fluid containing an organic compound containing oxygen atoms and a second fluid containing gas or mist-like water into a chamber, and a light source for irradiating ultraviolet light having an intensity in a wavelength range of 205 nm or less toward the first fluid and the second fluid within the chamber, and hydrophilizing the surface layer of a workpiece with the first fluid irradiated with ultraviolet light and the second fluid irradiated with ultraviolet light.

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