Patent Application
20090130372
The present invention relates to an adhesive structure and a manufacturing method thereof. More specifically, the present invention relates to an adhesive structure that forms a minute structure on a surface of a base thereof, thus being capable of adhering onto an adhesion target without using welding, an adhesive, or the like, and relates to a manufacturing method of the adhesive structure.
Heretofore, adhesion using welding or an adhesive, adhesion using an interposed fastening member such as a hook-and-loop fastener and a bolt, and the like have been employed in adhesion of materials.
However, in manufacturing processes of these adhesive structures, for example, there have existed adhesive materials such as the bolt, the hook-and-loop fastener body and the adhesive, and fastening apparatuses such as a tooling machine for fastening the bolt, an adhesive coating machine and a spot welding machine, and accordingly, there have been various problems owing to restrictions caused therefrom. For example, in the welding, the welding apparatus and a spark prevention measure have been required, and in the adhesive, a countermeasure has been required, which is against a work environment where a solvent volatilizes and adheres onto clothes of a worker. Moreover, also in the case of the adhesion by the hook-and-loop fastener, the adhesive has been used for fixing the hook-and-loop fastener itself to an adhesion target.
In order to solve these problems, such a countermeasure of changing the adhesive to a non-solvent adhesive of a hot-melt type has been taken in the field of the environment; however, as steps, there have been a coating step and a heating step, and accordingly, there have been problems such as an increase of working hours and an increase of cost. Moreover, also in the welding, friction welding and the like have been developed; however, even in this case, development and introduction of new equipment have been required, which has not leaded to reduction of the hours required for the steps and reduction of the cost.
Meanwhile, there have been proposed a functional board and a functional device, which include a group of minute protrusions of organic polymer, and proposed a microbiochip and an optical device, which use these minute protrusions (refer to Japanese Patent Unexamined Publication No. 2004-170935).
The present invention has been made in order to solve the above-described problems. It is an object of the present invention to provide an adhesive structure capable of adhering onto the adhesion target without requiring the adhesive materials or the adhesion apparatuses, such as the welding and the adhesive, and to provide a manufacturing method of the adhesive structure.
An adhesive structure according to a first aspect of the present invention includes: a base; and a plurality of protrusions, in which tip ends are spherical with a radius of 300 nm or less, and a radius of cross sections perpendicular to a longitudinal direction is 300 nm or less, the protrusions being provided on a surface of the base.
A method of manufacturing an adhesive structure according to a second aspect of the present invention includes the steps of: forming protrusions, in which tip ends are spherical with a radius of 300 nm or less, and a radius of cross sections perpendicular to a longitudinal direction is 300 nm or less; and providing the protrusions on a surface of a base.
A description will be made below in detail of embodiments of an adhesive structure of the present invention and a manufacturing method thereof based on the drawings.
As shown in
Specifically, as shown in
F∝A/D2 (1)
In the expression (1), algebraic symbol A indicates a constant depending on a dielectric constant of a material of the protrusions, and algebraic symbol D indicates a nearest distance between the protrusions 1 and the adhesion target 2.
As shown in
The protrusions 1 in the adhesive structure 10 of the present invention have the columnar structure in which the radius of the cross sections of the protrusions 1, which are perpendicular to the longitudinal direction thereof, is 500 nm or less. When the radius of the protrusions exceeds 500 nm, the protrusions 1 are hindered from entering the minute irregularities of the surface of the adhesion target 2, and the van der Waals force comes not to act therebetween. Meanwhile, when the radius is less than 50 nm, the adjacent protrusions 1 sometimes stick to one another. Hence, the radius of the cross sections of the protrusions 1 is preferably within a range of 50 to 500 nm, more preferably, 50 to 300 nm inclusive.
Here, as shown in (a) to (d) of
Moreover, as shown in
Note that a shape of the cross sections of the protrusions 1, which are with respect to the longitudinal direction thereof, is preferably circular; however, without being limited to this, the shape may be polygonal such as tetragonal and pentagonal.
Moreover, it is preferable that the above-described protrusions be made of a material with a dielectric constant of 2 or more (ASTMD 150, @ 1 MHz, 20° C.). When the dielectric constant is less than 2, the van der Waals force acting on the tip ends of the protrusions is not sufficient, and the adhesion strength is prone to be insufficient.
Furthermore, from a viewpoint of controlling the dielectric constant of the material, it is preferable that the protrusions be made of a composite material containing a conductive substance. As such a conductive substance, there can be mentioned: a carbon raw material such as carbon black, graphite, black lead and carbon nanotube; particles of metal such as copper, silver and nickel; indium tin oxide; titanium oxide; metal fiber such as stainless steel fiber; and the like.
Still further, it is preferable that the material of the above-described protrusions be resin. In the case where the protrusions are composed of the resin, when the protrusions contact the surface of the adhesion target, the protrusions are deformed owing to flexibility/collapsibility of the resin, whereby the number of contacts with the minute irregularities of the surface of the adhesion target is increased, thus making it possible to further ensure the adhesion strength. As the resin composing the protrusions, there can be suitably used: acrylic resin such as polymethacrylate and polyacrylate; polyamide resin such as 6-Nylon and 6,6-Nylon; polyolefin resin such as polystyrene, polyethylene and polypropylene; polyvinyl chloride; polyurethane; polycarbonate; polyacetal; polytetrafluoroethylene; and the like. Moreover, a composite resin material such as a particle reinforced one, a fiber reinforced one and a mineral reinforced one can also be suitably used.
Moreover, from a viewpoint of the flexibility/collapsibility of the protrusions, it is preferable that a bending elastic modulus of the protrusions be 5 GPa or less. When the bending elastic modulus exceeds 5 GPa, it becomes difficult to ensure the flexibility for allowing the protrusions to follow the shape of the minute irregularities of the adhesion target.
Furthermore, it is more preferable that the resin composing the above-described protrusions be a material of which dielectric constant and bending elastic modulus belong to the above-described ranges.
Moreover, it is preferable that an aspect ratio of the above-described protrusions be within a range of 1 to 15. When the aspect ratio is less than 1, it becomes difficult for the protrusions to follow the adhesion target, and the entire adhesion strength becomes prone to be decreased. When the aspect ratio exceeds 15, the protrusions are sometimes broken by a pressing pressure. It is more preferable that the aspect ratio be within a range of 1 to 4. In this case, the protrusions are less likely to collapse at the time of manufacture thereof, and a yield thereof can be improved. Note that, in this specification, as shown in
In the adhesive structure of the present invention, it is possible to coat, on the above-described protrusions, a thin film with a thickness of 300 nm or less. Specifically, as shown in
Note that the protrusions may have a hollow shape formed of only the thin film. Typically, it is possible to form such a thin film by chemical vapor deposition (CVD) and physical vapor deposition (PVD), which use a vacuum state, a plasma state and the like, dipping into a solution, and the like.
Moreover, while the adhesive structure of the present invention is composed by forming the plurality of minute protrusions 1 on the base 4 as shown in
Furthermore, the adhesive structure of the present invention can be provided with a distribution of the adhesion strength. For example, the protrusions are arrayed while setting a distance among the protrusions at an unequal pitch, thus making it possible to easily peel the adhesive structure from the adhesion target in the case of reusing or tearing down the adhesive structure firmly adhered thereonto. Moreover, it is possible to set the unequal pitch of the protrusions freely in any of lengthwise, crosswise and oblique directions. Furthermore, it is also possible to set such an inter-protrusion distance for each of the protrusions or for each of units, each of which is formed by combining an arbitrary number of the protrusions.
Moreover, it is possible to form the protrusions integrally with the surface of the base by a transcription method, an injection molding method, and the like. These methods enable the protrusions to be formed also on a surface of the composite resin material. In the resin material into which a reinforcement material (filler) is mixed, in general, the reinforcement material is not exposed to the surface of the resin material, but is covered with a resin layer. Accordingly, a resin component of the surface is softened and molded, whereby the protrusions composed only of the resin component can be obtained.
In the adhesive structure of the present invention, the same material as that of the protrusions 1 can be used as the base 4 on which the protrusions 1 are formed. Besides the above, a variety of materials can be appropriately selected and used according to purposes. For example, a metal oxide such as alumina, resin such as polyimide resin and epoxy resin, metals such as aluminum, silicon, iron, titanium and magnesium, glass, and the like can be used.
Moreover, the hook-and-loop fastener can also be obtained by using the adhesive structure of the present invention. Specifically, in two of the adhesive structures, surfaces thereof on which the protrusions are formed are contacted with each other, whereby the hook-and-loop fastener can be obtained. The surfaces of the adhesive structures, on which the protrusions are formed, are contacted with each other, whereby the van der Waals force acts between the protrusions, and the adhesive structures can be firmly adhered onto each other.
Next, a description will be made of the manufacturing method of the adhesive structure of the present invention.
In the manufacturing method of the present invention, the protrusions 1 and the base 4 are integrally formed by the transcription method, whereby the above-described adhesive structure is obtained. For example, it is possible to form the protrusions by so-called stamp molding of heating the base, thrusting a molding die against the base, and flowing the resin therein (refer to
Moreover, in another manufacturing method of the present invention, the protrusions 1 and a base 5 are formed separately from each other, and then the protrusions 1 and the base 5 are integrated with each other, whereby the above-described adhesive structure can be obtained. Specifically, after the protrusions 1 are formed on a film or the like in advance, the protrusions 1 are integrated with the base 5 made of the glass, the metal, the ceramics, the resin or the like, whereby the adhesive structure can be obtained (refer to
Here, the transcription method (nanoimprinting method) is a method capable of producing ultraprecise resin surfaces in quantity at low cost by a molding die processed minutely to a nanometer size. As the die (stamper) for use, there are dies in which grooves are formed on silicon, ceramics (SiC) and the like by an electron beam lithography method, metal dies formed by inversion of these by electroforming, and the like. Moreover, as the transcription method, there are a heating type (hot-emboss method), an ultraviolet curing type (UV curing method), and the like.
The present invention will be described below more in detail by examples and a comparative example; however, the present invention is not limited to these examples.
In each of the examples, the adhesive force and the dielectric constant were measured by the following methods.
Glass, iron plates, silicon wafers were used as the adhesion targets. Each of the adhesion targets was mounted on the surface having the protrusions, and a load of 100 g was applied thereto, and the adhesion target and the surface were left standing for 30 minutes. Thereafter, the adhesion strength was measured by tensile strength.
The dielectric constant was measured in conformity with ASTMD 150. Measurement conditions were set at 1 MHz and 20° C.
Polystyrene films (PS films; dielectric constant: 2.5) with a thickness of 200 μm were fabricated by a spin casting method. Thereafter, on a surface of each of the films, a sample with an area of 5 mm square was fabricated by the nanoimprinting method. On the sample, columnar protrusions with a tip end radius of 90 nm and a length of 1.2 μm were arrayed at an interval of 180 nm.
When the adhesive forces were measured by using these samples, the adhesion strengths became 43.1 N/cm2 in the glass, 68.1 N/cm2 in the iron plate, and 74.7 N/cm2 in the silicon wafer.
Polystyrene films (dielectric constant: 2.5) with a thickness of 200 μm were fabricated by the spin casting method. Thereafter, on a surface of each of the films, a sample with an area of 5 mm square was fabricated by the nanoimprinting method. On the sample, columnar protrusions with a tip end radius of 125 nm and a length of 1.2 μm were arrayed at an interval of 250 nm.
When the adhesive forces were measured by using these samples, the adhesion strengths became 31.0 N/cm2 in the glass, 49.0 N/cm2 in the iron plate, and 53.8 N/cm2 in the silicon wafer.
Polystyrene films (dielectric constant: 2.5) with a thickness of 200 μm were fabricated by the spin casting method. Thereafter, on a surface of each of the films, a sample with an area of 5 mm square was fabricated by the nanoimprinting method. On the sample, columnar protrusions with a tip end radius of 250 nm and a length of 1.2 μm were arrayed at an interval of 500 nm.
When the adhesive forces were measured by using these samples, the adhesion strengths became 15.6 N/cm2 in the glass, 24.5 N/cm2 in the iron plate, and 26.9 N/cm2 in the silicon wafer.
Polystyrene films (dielectric constant: 2.5) with a thickness of 200 μm were fabricated by the spin casting method. Thereafter, on a surface of each of the films, a sample with an area of 5 mm square was fabricated by the nanoimprinting method. On the sample, columnar protrusions with a tip end radius of 90 nm and a length of 1.2 μm were arrayed at an interval of 270 nm.
When the adhesive forces were measured by using these samples, the adhesion strengths became 19.2 N/cm2 in the glass, 30.2 N/cm2 in the iron plate, and 33.3 N/cm2 in the silicon wafer.
Polystyrene films (dielectric constant: 2.5) with a thickness of 200 μm were fabricated by the spin casting method. Thereafter, on a surface of each of the films, a sample with an area of 5 mm square was fabricated by the nanoimprinting method. On the sample, columnar protrusions with a tip end radius of 90 nm and a length of 1.2 μm were arrayed at an interval of 360 nm.
When the adhesive forces were measured by using these samples, the adhesion strengths became 10.8 N/cm2 in the glass, 17.0 N/cm2 in the iron plate, and 18.7 N/cm2 in the silicon wafer.
Polytetrafluoroethylene films (PTFE films; dielectric constant: 2.1) with a thickness of 200 μm were fabricated by the spin casting method. Thereafter, on a surface of each of the films, a sample with an area of 5 mm square was fabricated by the nanoimprinting method. On the sample, columnar protrusions with a tip end radius of 90 mm and a length of 1.2 μm were arrayed at an interval of 180 nm.
When the adhesive forces were measured by using these samples, the adhesion strengths became 33.2 N/cm2 in the glass, 52.3 N/cm2 in the iron plate, and 57.4 N/cm2 in the silicon wafer.
6-Nylon films (PA6 films; dielectric constant: 3.3) with a thickness of 200 μm were fabricated by the spin casting method. Thereafter, on a surface of each of the films, a sample with an area of 5 mm square was fabricated by the nanoimprinting method. On the sample, columnar protrusions with a tip end radius of 90 nm and a length of 1.2 μm were arrayed at an interval of 180 nm.
When the adhesive forces were measured by using these samples, the adhesion strengths became 66.0 N/cm2 in the glass, 103.9 N/cm2 in the iron plate, and 114.2 N/cm2 in the silicon wafer.
6-Nylon films (dielectric constant: 3.3) with a thickness of 200 μm were fabricated by the spin casting method. Thereafter, on a surface of each of the films, a sample with an area of 5 mm square was fabricated by the nanoimprinting method. On the sample, columnar protrusions with a tip end radius of 90 nm and a length of 1.2 μm were arrayed at an interval of 270 nm.
When the adhesive forces were measured by using these samples, the adhesion strengths became 25.6 N/cm2 in the glass, 46.2 N/cm2 in the iron plate, and 50.7 N/cm2 in the silicon wafer.
6-Nylon films (dielectric constant: 3.3) with a thickness of 200 μm were fabricated by the spin casting method. Thereafter, on a surface of each of the films, a sample with an area of 5 mm square was fabricated by the nanoimprinting method. On the sample, columnar protrusions with a tip end radius of 90 nm and a length of 1.2 μm were arrayed at an interval of 360 nm.
When the adhesive forces were measured by using these samples, the adhesion strengths became 14.4 N/cm2 in the glass, 26.0 N/cm2 in the iron plate, and 28.5 N/cm2 in the silicon wafer.
Vinyl chloride films (dielectric constant: 3.2) with a thickness of 200 μm were fabricated by the spin casting method. Thereafter, on a surface of each of the films, a sample with an area of 5 mm square was fabricated by the nanoimprinting method. On the sample, columnar protrusions with a tip end radius of 90 nm and a length of 1.2 μm were arrayed at an interval of 180 nm.
When the adhesive forces were measured by using these samples, the adhesion strengths became 46.4 N/cm2 in the glass, 73.0 N/cm2 in the iron plate, and 80.3 N/cm2 in the silicon wafer.
Polypropylene films (PP films; dielectric constant: 2.3) with a thickness of 200 μm were fabricated by the spin casting method. Thereafter, on a surface of each of the films, a sample with an area of 5 mm square was fabricated by the nanoimprinting method. On the sample, columnar protrusions with a tip end radius of 90 nm and a length of 1.2 μm were arrayed at an interval of 180 nm.
When the adhesive forces were measured by using these samples, the adhesion strengths became 43.5 N/cm2 in the glass, 68.5 N/cm2 in the iron plate, and 75.3 N/cm2 in the silicon wafer.
Polypropylene films (dielectric constant: 2.3) with a thickness of 200 μm were fabricated by the spin casting method. Thereafter, on a surface of each of the films, a sample with an area of 5 mm square was fabricated by the nanoimprinting method. On the sample, columnar protrusions with a tip end radius of 90 nm and a length of 1.2 μm were arrayed at an interval of 270 nm.
When the adhesive forces were measured by using these samples, the adhesion strengths became 16.9 N/cm2 in the glass, 30.5 N/cm2 in the iron plate, and 33.5 N/cm2 in the silicon wafer.
Polypropylene films (dielectric constant: 2.3) with a thickness of 200 μm were fabricated by the spin casting method. Thereafter, on a surface of each of the films, a sample with an area of 5 mm square was fabricated by the nanoimprinting method. On the sample, columnar protrusions with a tip end radius of 90 nm and a length of 1.2 μm were arrayed at an interval of 360 nm.
When the adhesive forces were measured by using these samples, the adhesion strengths became 9.5 N/cm2 in the glass, 17.1 N/cm2 in the iron plate, and 18.8 N/cm2 in the silicon wafer.
Polystyrene films (dielectric constant: 2.5) with a thickness of 200 μm were fabricated by the spin casting method. Thereafter, on a surface of each of the films, a sample with an area of 5 mm square was fabricated by the nanoimprinting method. On the sample, columnar protrusions with a tip end radius of 90 nm and a length of 1.2 μm were arrayed at an interval of 180 nm.
When the adhesive force in the case where two of the samples were used and the protrusions thereof were contacted with each other was measured, the adhesion strength became 37.6 N/cm2.
6-Nylon films (dielectric constant: 3.3) with a thickness of 200 μm were fabricated by the spin casting method. Thereafter, on a surface of each of the films, a sample with an area of 5 mm square was fabricated by the nanoimprinting method. On the sample, columnar protrusions with a tip end radius of 90 nm and a length of 1.2 μm were arrayed at an interval of 180 nm.
When the adhesive force in the case where two of the samples were used and the protrusions thereof were contacted with each other was measured, the adhesion strength became 88.0 N/cm2.
Polypropylene films (dielectric constant: 2.3) with a thickness of 200 μm were fabricated by the spin casting method. Thereafter, on a surface of each of the films, a sample with an area of 5 mm square was fabricated by the nanoimprinting method. On the sample, columnar protrusions with a tip end radius of 90 nm and a length of 1.2 μm were arrayed at an interval of 180 nm.
When the adhesive force in the case where two of the samples were used and the protrusions thereof were contacted with each other was measured, the adhesion strength became 38.2 N/cm2.
Polystyrene films with a thickness of 200 μm were fabricated by the spin casting method. Thereafter, on a surface of each of the films, carbon nanotubes (dielectric constant: 3.3) with a diameter of 1 to 10 nm and a length of 1 μm were implanted in a density of 4×1010 cm2, and a sample with an area of 5 mm square was fabricated.
When the adhesive forces were measured by using these samples, the adhesion strengths became 54.7 N/cm2 in the glass, 98.7 N/cm2 in the iron plate, and 108.4 N/cm2 in the silicon wafer.
Polystyrene films (dielectric constant: 2.5) with a thickness of 200 μm were fabricated by the spin casting method. Thereafter, on a surface of each of the films, a sample with an area of 5 mm square was fabricated by the nanoimprinting method. On the sample, columnar protrusions with a tip end radius of 600 nm and a length of 1.2 μm were arrayed at an interval of 1.2 μm.
When the adhesive forces were measured by using these samples, the adhesion strengths became 2.9 N/cm2 in the glass, 4.5 N/cm2 in the iron plate, and 5.0 N/cm2 in the silicon wafer.
In accordance with the examples and
Moreover, in accordance with Examples 1, 6, 7, 10 and 11, as the dielectric constant of the material composing the protrusions is becoming higher, the adhesion strength is enhanced. This is because, from the above-described expression (1), the van der Waals force rises as the dielectric constant is becoming higher.
Furthermore, from Examples 14 to 16, it is understood that the hook-and-loop fastener using the adhesive structures of the present invention has strong adhesion strength.
Still further, from Example 17, it is understood that strong adhesion strength can be obtained even if the adhesive structure of this application is formed by embedding the separately fabricated protrusions into the surface of the base.
The entire contents of Japanese Patent Application No. 2005-263762 (filed on Sep. 12, 2005) are incorporated herein by reference.
The description has been made above of the contents of the present invention along the embodiments and the examples; however, it is self-obvious to those skilled in the art that the present invention is not limited to the descriptions of these, and that various modifications and improvements are possible. Specifically, it is possible to form the protrusions in the present invention not only on the base but also on the surface of the adhesion target. In this case, there is also an effect that the protrusions are intertwined with each other, and a more robust adhesive structure can be obtained.
The minute protrusions are formed on the surface of the base of the structure or the like, thus making it possible for the structure to adhere onto the opposite member without requiring the adhesive materials such as the adhesive or the adhesion apparatuses. In such a way, simplification and cost reduction of a manufacturing process of industrial products can be realized.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2005-263762 | Sep 2005 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2006/315809 | 8/10/2006 | WO | 00 | 3/5/2008 |
