JP4179984B2 - Highly water-repellent structure and method for producing the same - Google Patents

Description

  The present invention relates to a structure having high water repellency and a method for producing the same.

  Typical examples of conventional water-repellent films include fluorine-based resin films such as polytetrafluoroethylene (PTFE) and tetrafluoroethylene-hexafluoropropylene copolymer resin (FEP). Moreover, it is generally performed to impart water repellency by applying a fluorine coating agent, and films in which layers of a fluorine coating agent are formed on various films are commercially available. Furthermore, there is a method in which the surface of the substrate is roughened and the water repellent compound is chemically adsorbed on the surface (see Patent Document 1).

  In order to obtain a surface having water repellency, it is necessary to make the surface tension of the substance or object (structure) lower than the surface tension of water. As an index (numerical value) indicating the contact angle with water, the falling angle with respect to water, or the like is used. The contact angle is a portion where the free surface of the water droplet is in contact with the surface of the substance or object when the water drop is in contact with the surface of the substance or object, and the water droplet is an angle formed by the surface of the water droplet and the surface of the substance or object. It means the angle on the side that includes. The falling angle refers to the angle of the surface of the substance or object when the water droplet starts to fall when the surface of the substance or object is allowed to stand still and the surface of the substance or object is gradually inclined (horizontal plane). Angle).

JP 2002-53689 A

  However, in the conventional fluorine-based film, although a film having transparency is obtained, the water repellency is about 100 to 130 ° in terms of water contact angle, and a sufficiently satisfactory film is not obtained. It's real. In addition, when a water-repellent coating agent (such as a fluorine-based coating agent) is coated on a general-purpose film so that the film surface has a water-repellent function, the coating layer is removed by the water-repellent coating agent. There was a problem of separation.

Therefore, the subject of this invention is providing the highly water-repellent structure which can exhibit the outstanding water repellency, and its manufacturing method.
Another object of the present invention is to provide a highly water-repellent structure capable of stably maintaining high water repellency and a method for producing the same.

  As a result of intensive studies to solve the above problems, the inventors of the present invention have performed laser ablation by irradiating the surface of a mixture in which a polymer component and water-repellent fine particles are uniformly mixed with each other. The surface and the polymer component in the vicinity thereof are removed, and the uneven surface due to the water-repellent fine particles is exposed on the surface, so that excellent water repellency can be exhibited, and the high water repellency can be stably maintained over a long period of time. It was found that a highly water-repellent structure that can be maintained over a long period of time is obtained. The present invention has been completed based on these findings.

That is, the present invention relates to a polymer component comprising at least one fluororesin selected from vinylidene fluoride resin, hexafluoropropylene resin, hexafluoroacetone resin, and polytetrafluoroethylene resin, and 100 parts by weight of the polymer component. Is a structure containing 50 to 800 parts by weight of inorganic water-repellent fine particles, surface-modified to ablate the polymer component in the vicinity of the surface by laser irradiation , and contact angle of pure water (23 A highly water-repellent structure characterized in that it has a surface including a portion having a (° C.) of 140 ° or more.

The highly water-repellent structure of the present invention preferably further has a surface including a portion where the falling angle (23 ° C.) of pure water is 80 ° or less .

Examples of the inorganic water-repellent particles, the contact angle of water on the surface (23 ° C.) is not preferable is 90 ° or more microparticles.

  The highly water-repellent structure preferably has a sheet shape or a film shape.

The present invention is also a method for producing the highly water-repellent structure, wherein at least one selected from a vinylidene fluoride resin, a hexafluoropropylene resin, a hexafluoroacetone resin, and a polytetrafluoroethylene resin. A substrate containing a polymer component made of a fluororesin and 50 to 800 parts by weight of inorganic water-repellent fine particles with respect to 100 parts by weight of the polymer component is irradiated with a laser to remove the surface and the polymer component in the vicinity thereof. A method for producing a highly water-repellent structure characterized by ablating. In the said manufacturing method, it is preferable that the fluence of a laser is 0.05-10 J / cm < ² >.

  According to the highly water-repellent structure of the present invention, excellent water repellency can be exhibited. Moreover, high water repellency can be maintained stably.

Hereinafter, embodiments of the present invention will be described with reference to the drawings as necessary. In addition, the same code | symbol may be attached | subjected to the same site | part or member.
[Highly water-repellent structure]
The highly water-repellent structure of the present invention is a structure containing a polymer component and water-repellent fine particles, and a portion having a contact angle (23 ° C.) of pure water of 140 ° or more (referred to as “high water repellency portion”). In some cases). Therefore, although the highly water-repellent structure of the present invention is a structure made of plastic material (plastic structure), the surface has a high water repellency with a contact angle of pure water larger than that of the conventional structure. The site | part is formed at least partially (partially or entirely), and can exhibit the outstanding high water repellency.

  The contact angle (23 ° C.) of pure water at the highly water-repellent portion on the surface of the highly water-repellent structure is not particularly limited as long as it is 140 ° or more (140 ° or more and less than 180 °), but preferably 145 ° or more. It is particularly preferable that the angle is 150 ° or more. The upper limit of the contact angle of pure water (23 ° C.) at the highly water-repellent portion of the surface of the highly water-repellent structure is not particularly limited as long as it is less than 180 °, and is, for example, 170 ° or less (preferably 165 ° The angle may be 160 ° or less.

  In the highly water-repellent structure of the present invention, the surface including a highly water-repellent portion having a pure water contact angle (23 ° C.) of 140 ° or more (sometimes referred to as “highly water-repellent surface”) The water-repellent portion may be formed at least partially on the surface and does not have to be the entire surface. That is, the highly water-repellent structure has a contact angle (23 ° C.) of pure water of 140 ° or more in at least a part of the surface. Specifically, the highly water-repellent structure may have a pure water contact angle (23 ° C.) of a predetermined portion of the surface of 140 ° or more, and a pure water contact angle (23 ° C.) of the entire surface. It may be 140 ° or more.

  Further, in the highly water-repellent structure, the surface (highly water-repellent surface) including a highly water-repellent portion having a contact angle of pure water at 23 ° C. of 140 ° or more is at least one of all surfaces. And all the surfaces need not have highly water-repellent sites. That is, at least one surface of the highly water-repellent structure has a highly water-repellent portion having a pure water contact angle (23 ° C.) of 140 ° or more. Specifically, for example, when the highly water-repellent structure has a film-like form, at least one surface (one surface or both surfaces) has a pure water contact angle (23 ° C.) of 140 ° or more. It has a part.

  The contact angle of pure water on the surface of the highly water-repellent structure is, for example, a known or conventional method such as a liquid suitability method in which pure water droplets are formed on the surface and the droplets are measured from the side, or the Wilhelmy method. The contact angle measurement method can be used. As a method for measuring the contact angle of pure water on the surface of the highly water-repellent structure of the present invention, a liquid suitability method can be suitably employed. Specifically, after placing a highly water-repellent structure on the stage (horizontal state) of a contact angle measurement meter using a contact angle measurement meter (for example, “CA-X” manufactured by Kyowa Interface Science Co., Ltd.) Pure water droplets on the surface of the highly water-repellent structure are formed by forming droplets of pure water on the surface (horizontal state) of the highly water-repellent structure and measuring the contact angle by checking the droplets with a microscope from the side. The contact angle can be measured.

  In the case where the highly water-repellent structure has a portion where the contact angle (23 ° C.) of pure water is less than 140 ° (sometimes referred to as “low water repellency portion”), The contact angle of pure water (23 ° C.) is not particularly limited, but is desirably 90 ° or more (preferably 100 ° or more, more preferably 120 ° or more).

  As described above, the highly water-repellent structure of the present invention has a highly water-repellent portion having a pure water contact angle (23 ° C.) of 140 ° or more on the surface. In addition, as long as such a highly water-repellent part is formed at least partially on one surface, the shape thereof is not particularly limited. For example, the shape is linear, curved, circular, polygonal, or a combination thereof. Examples include a shape that is partially formed on the surface in various shapes (for example, a pattern shape), a shape that is formed over the entire surface, and the like. In addition, as a highly water-repellent structure, from the viewpoint of effectively exhibiting the high water repellency, the highly water-repellent part is 50% or more with respect to the entire surface on which the highly water-repellent part is formed (preferably 70% or more, more preferably 90% or more).

  The highly water-repellent structure is composed of a resin composition containing a polymer component and water-repellent fine particles, and a contact angle (23 ° C.) of pure water at least at a part of the surface should be 140 ° or more. For example, the structure is not particularly limited. As a highly water-repellent structure, a surface portion (including the vicinity of the surface) including an inside where a polymer component and water-repellent fine particles are uniformly or almost uniformly mixed, and a portion where the ratio of the polymer component is reduced from the inside. It is preferable that it is a structure which has the structure comprised by these. The highly water-repellent structure having such a structure is not a structure in which a layer containing water-repellent fine particles is formed on the surface, and the ratio of the polymer component at a predetermined portion of the surface portion is smaller than the ratio of the polymer component inside. It has the structure which becomes. The concentration gradient of the polymer component is merely generated in a form in which the ratio of the polymer component at a predetermined portion of the surface portion is reduced as compared with other portions such as the inside. In addition, the highly water-repellent structure having such a structure can be produced, for example, by processing using ablation of a polymer component by laser irradiation as shown below.

(Polymer component)
The polymer component is not particularly limited, and not only a polymer material having a single chemical structure including a copolymer but also a polymer alloy or polymer blend made of a plurality of polymer materials having different chemical structures may be used. it can. The polymer component may be either an organic polymer component or an inorganic polymer component, but an organic polymer component is preferred. The organic polymer component is not particularly limited, and various organic resins such as a thermoplastic resin, a thermosetting resin, and an ultraviolet curable resin can be used, and a thermoplastic resin is preferable.

  Specifically, examples of the polymer component include fluorine resins such as vinylidene fluoride resin, hexafluoropropylene resin, hexafluoroacetone resin, and polytetrafluoroethylene resin; methacrylates such as polymethyl methacrylate (PMMA). Styrene resins such as polystyrene, acrylonitrile-styrene copolymer (AS resin), acrylonitrile-butadiene-styrene copolymer (ABS resin); polyamide; polyimide (PI); polyetherimide (PEI); polyamideimide Polyesterimide; Polycarbonate (PC); Polyacetal; Polyarylene ether such as polyphenylene ether; Polyphenylene sulfide; Polyarylate; Polyaryl; Polysulfone (polysulfone); Polyether sulfones (PES) (polyether sulfone); Polyurethanes; Polyester resins such as polyethylene terephthalate (PET); Polyether ketones such as polyether ether ketone and polyether ketone ketone; Polybutyl acrylate, Polyacrylic Polyacrylic acid esters such as ethyl acid; Polyvinyl esters such as polybutoxymethylene; Polysiloxanes; Polysulfides; Polyphosphazenes; Polytriazines; Polycarboranes; Polynorbornene; Epoxy resin; Polyvinyl pyrrolidone; Polydienes such as polyisoprene and polybutadiene; Polyalkenes such as polyisobutylene; Polyethylene, polypropylene, ethylene-propylene copolymer, etc. Resins such as olefin resins (such as thermoplastic resin) including without being limited thereto. Only one type of polymer component may be used, or two or more types may be used in combination.

  In the processing by laser ablation as shown below, a part of the ablated polymer component adheres to the surface, or a part of the polymer component during the ablation remains on the surface. Since it may not be possible to remove all, the polymer component is the contact angle (23 ° C.) of pure water on the surface of the base material consisting only of the polymer component (base material having a smooth surface). Those exceeding 90 ° are preferred, and those more than 100 ° (particularly 120 ° or more) are more preferred.

  The contact angle of pure water on the surface of the polymer component is the same as the contact angle of pure water on the surface of the highly water-repellent structure after the polymer component is formed into a flat plate (for example, a liquid suitable method or It can be measured by a Wilhelmy method or the like. Specifically, after the polymer component is formed into a flat plate shape, the polymer component is placed on a stage (horizontal state) of a contact angle measuring meter (for example, “CA-X” manufactured by Kyowa Interface Science Co., Ltd.). The contact angle of pure water on the surface of the polymer component is measured by forming a drop of pure water on the surface (horizontal state) of the flat plate made of this polymer component, and measuring the contact angle by checking the droplet with a microscope from the side. Can be measured.

  Therefore, as the polymer component, a polymer component containing a fluorine-based resin can be suitably used, and a polymer component composed only of a fluorine-based resin is particularly preferable.

  In addition, as for fluorine resin, the contact angle (23 degreeC) of the pure water in the surface of the film which consists only of this fluorine resin is less than 140 degrees, and is about 100-130 degrees normally.

  As a polymer component, it can select suitably according to the use, physical property, etc. of a highly water-repellent structure.

  In the case of producing a highly water-repellent structure using a processing method by laser ablation as shown below, a polymer component having an absorption wavelength in the wavelength region of laser light is usually used as the polymer component. However, in the present invention, even when a polymer component that does not have an absorption wavelength in the wavelength region of the laser beam is used as the polymer component, the water-repellent fine particles absorb the irradiation energy of the laser beam, Even a polymer component that does not originally have an absorption wavelength in the wavelength region can be processed by laser ablation of the polymer. Therefore, in the present invention, the polymer component can be appropriately selected and used regardless of the type of laser light to be irradiated (for example, the wavelength region of the laser light to be irradiated).

(Water repellent fine particles)
The water-repellent fine particles are not particularly limited as long as they are water-repellent fine particles. For example, fine particles having a pure water contact angle (23 ° C.) exceeding 90 ° on the surface can be suitably used, and more preferably. Is preferably fine particles of 100 ° or more (particularly 120 ° or more). The water-repellent fine particles can be used alone or in combination of two or more.

  The contact angle of pure water on the surface of the water-repellent fine particles is determined by pressing the water-repellent fine particles to form a flat product, and then the contact angle of pure water on the surface of the highly water-repellent structure or the surface of the polymer component. Can be measured by the same method as in the case of the contact angle of pure water (for example, the liquid suitability method or the Wilhelmy method). Specifically, after forming the flat plate by pressing the water-repellent fine particles, the flat plate formed of the water-repellent fine particles is measured with a contact angle meter (for example, “CA-X” manufactured by Kyowa Interface Science Co., Ltd.). Is placed on the stage (horizontal state), and a droplet of pure water is formed on the surface (horizontal state) of the flat plate with these water-repellent fine particles, and the contact angle is measured by checking the droplet with a microscope from the side. Thus, the contact angle of pure water on the surface of the water-repellent fine particles can be measured.

  It is important that the water-repellent fine particles are fine particles. For example, the average particle diameter is preferably 300 μm or less (preferably 5 nm to 100 μm, more preferably 10 nm to 1,000 nm).

  As such water-repellent fine particles, water-repellent fine particles made of various materials (or raw materials) can be used, and any of inorganic water-repellent fine particles and organic water-repellent fine particles may be used. As the water-repellent fine particles, inorganic water-repellent fine particles can be suitably used.

  Inorganic water-repellent fine particles include periodic table group 1 elements such as lithium, sodium, potassium, rubidium and cesium; periodic table group 2 elements such as magnesium, calcium, strontium and barium; scandium, yttrium and lanthanoid elements (lanthanum, cerium) Periodic group 3 elements such as actinoid elements (actinium etc.); periodic table group 4 elements such as titanium, zirconium and hafnium; periodic table group 5 elements such as vanadium, niobium and tantalum; chromium, molybdenum, tungsten, etc. Periodic table group 6 elements; periodic table group 7 elements such as manganese, technetium and rhenium; periodic table group 8 elements such as iron, ruthenium and osmium; periodic table group 9 elements such as cobalt, rhodium and iridium; nickel, palladium and platinum Periodic table 10 elements such as copper, silver, gold, etc. Group 1 element; Group 12 element of periodic table such as zinc, cadmium, mercury; Group 13 element of periodic table such as boron, aluminum, gallium, indium, thallium; Group 14 element of periodic table such as silicon, germanium, tin, lead; A particulate inorganic compound containing an inorganic atom (inorganic element) such as a group 15 element of the periodic table such as antimony or bismuth; a group 16 element of the periodic table such as sulfur, or a carbon compound consisting only of carbon atoms. In addition, the said inorganic compound may contain the 1 type (s) or 2 or more types of inorganic type atom.

  As long as it has a fine particle form, the inorganic water-repellent fine particles may be composed of simple inorganic elements, including oxides of inorganic elements (including complex oxides), hydroxides, halides (chlorides, etc.) ), Oxo acid salts (nitrates, sulfates, phosphates, carbonates, etc.).

  The inorganic water-repellent fine particles include carbon-based water-repellent fine particles containing only carbon atoms; silicon-based water-repellent fine particles containing silicon atoms; metal-based repellent fine particles containing various metal atoms such as iron atoms, titanium atoms, and aluminum atoms. Water-based fine particles; phosphorus-based water-repellent fine particles containing phosphorus atoms; sulfur-based water-repellent fine particles containing sulfur atoms can be suitably used.

  Specifically, as the inorganic water-repellent fine particles, for example, carbon black fine particles, acetylene black fine particles, silica fine particles, iron powder fine particles, ferrite fine particles, titanium oxide And the like.

  The surface of the water-repellent fine particles may be subjected to various surface treatments. For example, a water-repellent surface treatment for imparting water repellency may be performed. Therefore, as the water-repellent fine particles, water-repellent fine particles that have been subjected to a water-repellent surface treatment so that the contact angle (23 ° C.) of pure water on the surface exceeds 90 ° can also be used.

  The ratio of the water-repellent fine particles is not particularly limited, and can be selected, for example, from 10 to 1000 parts by weight, preferably 50 to 800 parts by weight (more preferably 100 to 100 parts by weight) with respect to 100 parts by weight of the polymer component. 500 parts by weight). When the ratio of the water-repellent fine particles is more than 1000 parts by weight with respect to 100 parts by weight of the polymer component, the strength of the sheet or film due to the polymer component network is lowered. The effect of the reduction is reduced.

  The highly water-repellent structure of the present invention includes, for example, various additives such as pigments and hydrophilic fine particles as long as it can maintain excellent water repellency as a component other than the polymer component and the water-repellent fine particles. It may be.

  Note that the highly water-repellent structure of the present invention has a surface including a portion where the falling angle (23 ° C.) of pure water is 80 ° or less (preferably 65 ° or less, more preferably 40 ° or less, particularly 10 ° or less). It is suitable to have. In particular, if the contact surface (23 ° C.) of pure water has a surface including a portion where the drop angle (23 ° C.) of pure water is 80 ° or less, the surface water repellency is further improved. It can be exhibited more effectively. If the highly water-repellent structure has a pure water falling angle (23 ° C.) of more than 80 °, the water droplets are highly adherent to the surface and will not easily fall off.

  The falling angle of pure water on the surface of the highly water-repellent structure can be measured by a known or conventional falling angle measuring method. Specifically, after placing a highly water-repellent structure on the stage (horizontal state) of a contact angle measurement meter using a contact angle measurement meter (for example, “CA-X” manufactured by Kyowa Interface Science Co., Ltd.) Forming pure water droplets on the surface (horizontal state) of the highly water-repellent structure and gradually tilting the stage on which the highly water-repellent structure is placed while checking the droplets from the side with a microscope At this time, by measuring the angle of the stage when the pure water droplet starts to fall, the falling angle of pure water on the surface of the highly water-repellent structure can be measured.

  Moreover, the highly water-repellent structure of the present invention may have a porous structure (for example, a porous structure having open cells, a porous structure having closed cells, etc.). When the highly water-repellent structure has a porous structure, the uneven surface derived from the porous structure has a shape with unevenness due to the water-repellent fine particles, compared to the case where it does not have a porous structure. Thus, it becomes possible to exhibit even more excellent high water repellency. The highly water-repellent structure having such a porous structure has a porous structure having a porosity of 1 to 80% (preferably 5 to 70%, more preferably 10 to 60%). desirable. As described above, when the highly water-repellent structure has a porous structure having a porosity of 1 to 80% (particularly, a porous structure having open cells), the highly water-repellent structure is converted into a water-repellent filter or the like. Can also be used.

  The shape of the highly water-repellent structure is not particularly limited and may be any shape as long as it is composed of a polymer component and water-repellent fine particles. For example, a sheet-like or film-like shape or a plate In addition to the shape, a polyhedron shape, a shape consisting of only a spherical surface (spherical shape, etc.), a shape consisting of a flat surface and a spherical surface (cylindrical shape, conical shape, dome shape, etc.) and the like can be mentioned.

  In addition, when the highly water-repellent structure has a sheet-like or film-like shape, the thickness of the highly water-repellent structure can be appropriately selected according to the application, for example, 0.1 to 500 μm. (Preferably 1 to 300 μm, more preferably 10 to 150 μm). Since the highly water-repellent structure may have a plate shape or a polyhedral shape, the thickness of the highly water-repellent structure can be selected from a range of 0.1 μm or more, for example.

  Further, the surface on which the highly water-repellent portion of the highly water-repellent structure is formed may be a flat surface or a spherical surface. Of course, both a flat surface and a spherical surface may be used.

(Production method)
The method for producing a highly water-repellent structure according to the present invention includes a polymer component and water-repellent fine particles, and has a surface including a portion having a pure water contact angle (23 ° C.) of 140 ° or more. The method is not particularly limited as long as it is a method capable of obtaining a highly water-repellent structure. For example, it is composed of a resin composition containing a polymer component and water-repellent fine particles, and the ratio of the polymer component is reduced from the inside in which the polymer component and the water-repellent fine particles are uniformly or almost uniformly mixed. A highly water-repellent structure having a structure constituted by a surface portion (including the vicinity of the surface) including a site is formed on a base material containing a polymer component and water-repellent fine particles, for example, as shown in FIG. It can be manufactured by irradiating a laser to ablate the polymer component in the surface and a predetermined portion in the vicinity of the surface, thereby at least partially modifying the surface of the substrate. By this ablation of the polymer component, the ratio of the polymer component at the surface of the substrate and the portion irradiated with the laser in the vicinity of the surface is reduced from that before irradiation. When a base material in which the components are uniformly or almost uniformly mixed is used, the proportion of the polymer component at the surface of the base material and the portion irradiated with the laser near the surface is higher than the inside due to ablation of the polymer component. Will be reduced. In other words, the ratio of the water-repellent fine particles in the surface of the base material and the portion irradiated with the laser in the vicinity of the surface is increased, thereby obtaining a highly water-repellent structure. In particular, the portion of the surface on which the polymer component was ablated is a surface (uneven surface) in which a minute uneven structure is formed by water-repellent fine particles, and the contact angle (23 ° C.) of pure water at the portion is 140 ° or more. It has become.

  As described above, in the present invention, the highly water-repellent structure can be formed by surface modification by laser irradiation, and specifically, it is formed by surface modification by ablating the surface and a polymer component in the vicinity thereof by laser irradiation. be able to.

  The amount of the polymer component removed by ablation is not particularly limited as long as the contact angle (23 ° C.) of pure water is 140 ° or more due to the removal of the polymer component by ablation. The contact angle (23 ° C.) can be selected as appropriate.

  Further, the substrate is not particularly limited as long as it is a substrate composed of a resin composition containing a polymer component and water-repellent fine particles, but the components such as the polymer component and water-repellent fine particles are uniformly or almost uniformly mixed. The base material comprised by the resin composition which can be used can be used suitably. That is, as a substrate for obtaining a highly water-repellent structure, a substrate in which components such as a polymer component and water-repellent fine particles are uniformly or almost uniformly dispersed is suitable. Such a substrate can be formed using a known molding method (for example, an extrusion molding method, a molding method using a mold, or the like). In addition, the shape of the substrate can be appropriately selected according to the shape of the target highly water-repellent structure.

  FIG. 1 is a schematic bird's-eye view showing an example of a method for producing a highly water-repellent structure according to the present invention. In FIG. 1, 1 is a base material, 1a is the upper surface (surface) of the base material 1, 21, 22,..., 2n-1, 2n (n is an integer of 1 or more), respectively. Irradiated site [sometimes referred to as “laser irradiation unit”; (21, 22,..., 2n−1, 2n) may be collectively referred to as laser irradiation unit 2], 3 is irradiated by laser 4 4 (laser 4a is a lens, 5 is a lens, 5 is a focal point of the laser 4, 6 is an irradiation direction of the laser 4, and 7 is a movement of the focal point 5 of the laser 4). Direction. A is an XY stage. The substrate 1 is a plastic substrate in which a polymer component and water-repellent fine particles are uniformly or almost uniformly mixed. Further, an fθ lens is used as the lens 4a.

  In FIG. 1, the laser 4 irradiates the substrate 1 in the direction of the irradiation direction 6, that is, in a direction parallel to the Z axis. The laser 4 can be focused by using the lens 4a. The substrate 1 has a film-like form, and the upper surface 1a of the substrate 1 is a plane parallel to the XY plane (or perpendicular to the Z axis).

  Further, the laser 4 irradiates the focal point 5 while moving the focal point 5 in the direction of the movement direction 7 (that is, the direction parallel to the X axis) in a line shape. The moving direction 7 is a direction perpendicular to the irradiation direction 6 and parallel to the surface 1 a of the substrate 1. The moving speed of the focal point 5 when moving the focal point 5 of the laser 4 in a line shape in the moving direction 7 is not particularly limited, and is, for example, 10 to 1,000,000 μm / second (preferably 100 to 10). , 000 μm / second).

  In this way, the laser 4 is irradiated by irradiating the base 4 with the laser 4 focused on the surface 1a of the base 1 and moving in the moving direction 7 which is perpendicular to the irradiation direction 6. In the portion (laser irradiation part) 2 formed, ablation (explosive scattering phenomenon) occurs in the polymer component constituting the substrate 1, thereby removing the polymer component and increasing the contact angle of pure water (23 ° C.). A part (high water repellency part) of 140 ° or more is formed. On the other hand, in the part (laser non-irradiation part) 3 where the laser 4 is not irradiated, it is not affected by the laser irradiation and maintains the original state, and the pure water contact angle (23 ° C.) is 140. It is less than °.

  More specifically, the laser beam 4 is irradiated in the direction of the irradiation direction 6 with the focal point 5 being focused on one end portion of the laser irradiation unit 2 to be one of the laser irradiation units. Is moved in a line in the direction of movement 7 to the other end. Thereafter, the focal point 5 of the laser 4 is moved in a line to the other end in accordance with a method similar to the moving method of the focal point 5 in accordance with one end of the part to be the other laser irradiation part. Furthermore, by repeating the movement of such a focal point as necessary, a laser irradiation part can be formed and a highly water-repellent part can be formed.

  The laser focal point can be moved by moving the relative position between the laser and the lens and the substrate, for example, by moving the laser and the lens and / or the irradiated substrate. Specifically, the laser irradiation is performed by, for example, placing the irradiated sample (irradiated substrate) on a precise XY stage that can be moved precisely in a two-dimensional direction and moving it two-dimensionally. Samples can be made anywhere. Further, it may be moved two-dimensionally or three-dimensionally using a precise XYZ stage that can be moved precisely in two-dimensional or three-dimensional directions. Therefore, the focal point of the laser can be moved in the irradiation direction.

  FIG. 2 shows a cross-sectional model diagram of a highly water-repellent structure obtained by such a manufacturing method (a manufacturing method using surface processing by laser irradiation). FIG. 2 shows a cross-sectional model diagram of the highly water-repellent structure obtained by the manufacturing method shown in FIG. 1, and FIG. 2 (a) is a cross-sectional model diagram of the substrate before laser irradiation, and FIG. ) Is a model diagram of a highly water-repellent structure which is a substrate after laser irradiation. In FIG. 2, 81 is a substrate before laser irradiation (substrate not irradiated with laser), 81a is the surface of the substrate 81, 82 is a highly water-repellent structure which is a substrate after laser irradiation, and 82a is highly water-repellent. The surface of the structure 82, 82b is a recess formed on the surface 82a of the highly water-repellent structure 82, 8a is a polymer component particle, and 8b is a water-repellent fine particle. 2A, the base material 81 has a smooth surface 81a, and the inside is in a state where the particles of the polymer component 8a and the water-repellent fine particles 8b are uniformly or almost uniformly mixed. Plastic substrate. When the substrate 81 is subjected to surface processing by laser irradiation as shown in FIG. 1, a highly water-repellent structure 82 as shown in FIG. 2B is produced. In the highly water repellent structure 82, the surface 82a has little or no particles of the polymer component 8a, the concave portion 82b is formed, and the surface is a rough surface formed by the water repellent fine particles 8b. This is a plastic structure in which the polymer component particles 8a and the water-repellent fine particles 8b are mixed uniformly or almost uniformly. As described above, the surface treatment by laser irradiation removes the surface of the base material and the polymer component particles in the vicinity of the surface by ablation, thereby forming a surface having an uneven surface by the water-repellent fine particles.

  Note that FIG. 2 is a model diagram and includes simplified contents for easy explanation. For example, in FIG. 2, a particulate polymer component (polymer component particles) is used as the polymer component, but the shape of the polymer component in the substrate is not particularly limited. It may be a shape such as a matrix shape. Of course, the polymer component in the substrate may have a shape in which these shapes are combined.

  In FIG. 2, the particle shape of the particulate polymer component and the water-repellent fine particles are both perfect circles, and the sizes thereof are the same. The size is not particularly limited, and is usually an indefinite shape (the size and shape are irregular). Furthermore, both the particulate polymer component and the water-repellent fine particles are regularly arranged, but the arrangement form of these particles is not particularly limited and is usually irregularly arranged. It has a form.

  As described above, in the present invention, a highly water-repellent structure having excellent water repellency, which is not conventionally available, can be produced by a simple method of laser irradiation.

(laser)
The laser to be irradiated is not particularly limited as long as it can cause ablation to the polymer component constituting the substrate. In addition, as a laser, even if the wavelength of the laser beam is not at the absorption wavelength of the polymer component (absorption peak wavelength or its region), the polymer component may be ablated due to the effect of laser absorption by the water-repellent fine particles. There are cases where it is possible. In some cases, the polymer component can be ablated by going through a multiphoton absorption process. Therefore, as a laser, a laser having an oscillation wavelength at the absorption wavelength of the polymer component, or a wavelength region that is a harmonic of the absorption wavelength of the polymer component (for example, a second harmonic, a third harmonic, a fourth harmonic, etc.) In addition, a laser having an oscillation wavelength, a laser capable of absorbing irradiation energy in the water-repellent fine particles (such as a laser having an oscillation wavelength at the absorption wavelength of the water-repellent fine particles), and the like can be used.

  Specifically, as a laser having an oscillation wavelength of 400 nm or less, for example, a KrF excimer laser with an oscillation wavelength of 248 nm, an XeCl excimer laser with an oscillation wavelength of 308 nm, or a YAG laser with an oscillation wavelength of 355 nm is used. A third harmonic, a fourth harmonic of a YAG laser having an oscillation wavelength of 355 nm, or the like can be preferably used.

On the other hand, the laser having an oscillation wavelength exceeding 400 nm is not particularly limited as long as it is a laser capable of causing ablation of a polymer component via a multiphoton absorption process, for example, via a multiphoton absorption process. It is possible to cause the base material to absorb light in the ultraviolet wavelength region, and to cause the base material to ablate by the light absorption, the wavelength is around 750 nm to 800 nm, and the pulse width is 1 × 10 ^−9. Lasers of seconds (0.000000001 seconds) or less (sometimes referred to as “ultra-short pulse laser”) can be preferably used. Examples of such an ultrashort pulse laser include a laser using a titanium / sapphire crystal as a medium (titanium sapphire laser).

  Note that light absorption via a multiphoton absorption process means light absorption in which a plurality of photons are simultaneously absorbed by a substance when a high-density photon exists, and this multiphoton absorption process is used. In laser processing, it is possible to perform processing by utilizing a phenomenon that cannot originally occur with the energy of one photon. In addition, since the processing uses a nonlinear phenomenon, processing exceeding the diffraction limit of the irradiation wavelength is possible despite the use of light.

  The laser can be appropriately selected according to the type of polymer component, the type of water-repellent fine particles, and the like.

In the present invention, the fluence of the irradiating laser (laser fluence) is not particularly limited, is preferably from 0.05~10J / cm ^2, particularly 0.1~8J / cm ² (0.15~5J / Cm ² ). If the laser fluence is less than 0.05 J / cm ² , sufficient ablation cannot be caused and the effect may not be sufficient. On the other hand, if the laser fluence exceeds 10 J / cm ² , the power is very high. Since it becomes strong, the disappearance of the base material becomes large, and even if the effect is obtained, an excessive amount is etched.

  Since the highly water-repellent structure of the present invention has a highly water-repellent portion having a contact angle (23 ° C.) of pure water of 140 ° or more at least partially on the surface thereof, the water-repellent structure is utilized. It can be suitably used in applications. For example, when the highly water-repellent structure has a porous structure (particularly, a porous structure having open cells), it can be used as a water-repellent filter, a water-repellent membrane, a water-repellent separator, and the like.

  The highly water-repellent structure of the present invention may be used as it is as a plastic member, or may be used in combination with other members. The highly water-repellent structure can be subjected to arbitrary processing and processing, for example, processing such as stretching and shrinking, and further post-processing can be performed as necessary.

  In addition, according to the method of the present invention, high water repellency can be imparted to a plastic substrate that does not have high water repellency, so that the added value of the plastic substrate can be increased.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples. Example 3 is not included in the scope of the present invention, but is described as a reference.

(Example 1)
Trade name “D2E” [manufactured by Daikin; polytetrafluoroethylene (PTFE) dispersion] and trade name “# 4500” (manufactured by Tokai Carbon Co., Ltd .; carbon black), former: latter = 1: 3 (weight) Ratio: PTFE dispersion was in the ratio of solid content), and the mixture was mixed in an aqueous medium for 2 minutes using a mixer, and then this mixture was poured into methanol to obtain a coagulated product. Further, the coagulated material was subjected to filtration treatment and then dried at 100 ° C. for 2 hours to remove the solvent. To this, n-dodecane was added as an auxiliary so that the solid content was 55% by weight, filled into a metal tube, subjected to pressure preforming at 0.2 MPa, and then a ram extruder (Reduction Ratio). (RR) = S ₀ / S ₁ = 50; S ₀ was extruded at the exit area, and S ₁ was the inlet area) to obtain a round bar-shaped (cylindrical) extruded product having a diameter of 20 mm and a length of 10 m.

  Next, this round bar-shaped extrudate was rolled between metal rolls to obtain a sheet-like base material having a thickness of 0.2 mm and a width of 100 mm. This sheet-like substrate is dried at 150 ° C. to remove the auxiliary agent, and further, only the X-axis direction (length direction) of this sheet-like substrate is stretched twice, and the sheet-like substrate having a thickness of 150 μm. (May be referred to as “sheet-like substrate A”).

This sheet-like substrate A is cut into a predetermined size, placed on an XY stage, and shaped into a top hat, which is a YAG laser having a wavelength of 355 nm, a fluence of 0.28 J / cm ² and a repetition frequency of 30 kHz. The third harmonic (355 nm) is focused on the silicon wafer surface by an fθ lens to a diameter of 150 μm, and a laser beam is scanned at a speed of 200 mm / second by a galvano scanner to form an ablation line on the surface of 60 mm in length. Further, next to that, the center of irradiation was separated by 150 μm and the formation of a line was sequentially repeated 400 times to perform surface processing by laser irradiation to form a 60 mm square irradiation portion. With respect to the surface of the irradiated portion, the contact angle was measured to be 153 °, and the sliding angle was measured to be 8 °.

  Furthermore, using a reflection electron microscope (SEM) (manufactured by Hitachi, Ltd.), the surface of the irradiated portion in the sheet-like substrate A subjected to surface processing by laser irradiation was observed, and the result is shown in FIG. Thus, on the surface, aggregates of carbon black fine particles of about 40 nm were mainly observed, and polytetrafluoroethylene (PTFE) particles and fibers were hardly observed. Therefore, it was confirmed that the surface of the irradiated part was mainly composed of carbon black.

(Comparative Example 1)
A sheet-like substrate (sheet-like substrate A) having a thickness of 150 μm was produced in the same manner as in Example 1 except that laser irradiation was not performed. With respect to this sheet-like substrate A, the contact angle was measured to be 136 °, and when the falling angle was measured, it did not fall even at 90 °.

  In addition, when the surface of the sheet-like base material A was observed using a reflection electron microscope (SEM) (manufactured by Hitachi, Ltd.), as shown in FIG. 3B, the surface was polytetrafluoroethylene. It was confirmed that the particles and fibers of (PTFE) and carbon black were dispersed at the same ratio as the mixing ratio at the time of mixing.

  FIG. 3 is a view showing a photograph regarding the shape of the surface when observed with a reflection electron microscope (SEM), and FIG. 3 (a) is a sheet-like substrate subjected to surface processing by laser irradiation in Example 1. The photograph regarding the shape of the surface of the irradiation part in the material A is shown, and FIG. 3 (b) shows the photograph regarding the shape of the surface of the sheet-like substrate A in Comparative Example 1. In FIG. 3, “PTEF particles” means polytetrafluoroethylene (PTFE) particles, and “PTFE fibers” mean fibers made of polytetrafluoroethylene (PTFE). “CB fine particles” means carbon black (CB) fine particles.

(Example 2)
An N-methylpyrrolidone (NMP) solution of polyvinylidene fluoride (PVdF) (concentration: 20% by weight) and a trade name “# 4500” (manufactured by Tokai Carbon Co., Ltd .; carbon black), the former: the latter = 1: 3 ( After mixing at a ratio of weight ratio: PVdF NMP solution in terms of solid content, the solvent (NMP) was removed by drying at 230 ° C. to obtain a sheet-like substrate having a thickness of 0.2 mm (“sheet-like substrate B”). May be called).

  Surface treatment by laser irradiation was performed in the same manner as in Example 1 except that the sheet-like substrate B was used instead of the sheet-like substrate A. When the contact angle of the surface of the irradiated portion irradiated with laser during this surface processing was measured, it was 146 °, and the fall angle was 38 °.

(Example 3)
The toluene solution of polystyrene (concentration: 10% by weight) and the trade name “# 4500” (manufactured by Tokai Carbon Co., Ltd .; carbon black), the former: the latter = 1: 3 (weight ratio; the toluene solution of polystyrene is converted to a solid content) Then, the solvent (toluene) was removed by drying at 100 ° C. to obtain a sheet-like base material having a thickness of 0.2 mm (sometimes referred to as “sheet-like base material C”).

  Surface treatment by laser irradiation was performed in the same manner as in Example 1 except that the sheet-like substrate C was used instead of the sheet-like substrate A. When the contact angle of the surface of the irradiated part irradiated with laser during this surface processing was measured, it was 141 °, and the fall angle was measured, which was 65 °.

FIG. 1 is a schematic bird's-eye view showing an example of a method for producing a highly water-repellent structure according to the present invention. FIG. 2 shows a cross-sectional model diagram of the highly water-repellent structure obtained by the manufacturing method shown in FIG. 1, and FIG. 2 (a) is a cross-sectional model diagram of the substrate before laser irradiation, and FIG. ) Is a model diagram of a highly water-repellent structure which is a substrate after laser irradiation. FIG. 3 is a view showing a photograph regarding the shape of the surface when observed with a reflection electron microscope (SEM), and FIG. 3 (a) is a sheet-like substrate subjected to surface processing by laser irradiation in Example 1. The photograph regarding the shape of the surface of the irradiation part in the material A is shown, and FIG. 3 (b) shows the photograph regarding the shape of the surface of the sheet-like substrate A in Comparative Example 1.

Explanation of symbols

1 Base material 1a Upper surface (surface) of the base material 1
2 Part irradiated with laser 4 (laser irradiation part)
3 Site not irradiated with laser 4 (laser non-irradiated part)
DESCRIPTION OF SYMBOLS 4 Laser 4a Lens 5 Focus of laser 4 6 Irradiation direction of laser 4 7 Moving direction of focus 5 of laser 4 81 Base material before laser irradiation 81a Surface of base material 81 82 High water-repellent structure which is a base material after laser irradiation Body 82a Surface 82b of highly water-repellent structure 82b Recessed portion formed on surface 82a of highly water-repellent structure 82 8a Polymer component particles 8b Water-repellent particles

Claims (6)

A polymer component comprising at least one fluororesin selected from vinylidene fluoride resin, hexafluoropropylene resin, hexafluoroacetone resin, and polytetrafluoroethylene resin , and 50 to 800 with respect to 100 parts by weight of the polymer component A structure containing parts by weight of inorganic water-repellent fine particles, which is subjected to surface modification by ablating the surface and the polymer component in the vicinity thereof by laser irradiation, and the contact angle (23 ° C.) of pure water is 140 ° or more A highly water-repellent structure characterized by having a surface including a portion that is Furthermore, the highly water-repellent structure of Claim 1 which has the surface containing the site | part whose falling angle (23 degreeC) of pure water is 80 degrees or less. The highly water-repellent structure according to claim 1 or 2, wherein the inorganic water-repellent fine particles are fine particles having a water contact angle (23 ° C) of 90 ° or more on the surface thereof. The highly water-repellent structure according to any one of claims 1 to 3, which has a sheet-like or film-like shape. A method for producing the highly water-repellent structure according to any one of claims 1 to 4, comprising a vinylidene fluoride resin, a hexafluoropropylene resin, a hexafluoroacetone resin, and a polytetrafluoroethylene resin. A substrate containing at least one fluororesin selected from the following: a polymer component and 50 to 800 parts by weight of inorganic water-repellent fine particles with respect to 100 parts by weight of the polymer component; And a method for producing a highly water-repellent structure, characterized by ablating a polymer component in the vicinity thereof. Laser fluence of 0.05-10 J / cm ² The method for producing a highly water-repellent structure according to claim 5.

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