JP2007231072A - Coating composition and article using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating composition which is excellent in water resistance, insulation properties, and resistance to ultraviolet degradation and is useful to provide traffic signals and lighting apparatuses being nonbulky and having durability and high waterproofness by sealing electrical conduction parts such as wirings, electrical contacts, and wires. <P>SOLUTION: The coating composition substantially consists of a fluoropolymer being soluble in a solvent and having a molecular weight of not less than 10,000 and a solvent in which the fluoropolymer is dissolved. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a coating composition and its use. More specifically, the present invention relates to a water-resistant coating composition composed of a fluoropolymer soluble in a solvent, and a conductive part such as a wiring, an electrical contact, or an electric wire by applying it. The present invention relates to a stopped article, such as a light emitting diode (LED) device or an electronic device. Since the coating composition of the present invention is particularly excellent in water resistance, insulation, and UV degradation resistance, it is advantageous for articles mainly used outdoors, such as outdoor advertising devices, traffic signal devices, electric light display devices, road sign devices, and the like. Can be used for

  In traffic signal devices and the like, light-emitting devices equipped on them are rapidly shifting from light bulbs and fluorescent lamps to LEDs in order to save energy and reduce maintenance costs. For example, in traffic signals that can use a large and strong housing that can maintain high waterproof performance, most of these light emitting devices already use LEDs. In addition, the number of red taillights for automobiles that use LEDs is also increasing. In the device equipped with these light emitting devices, the LED itself takes the form of a small chip, but a large base is required to mount the LED chip, and a large transparent to ensure a waterproof function. A housing or cover is required. Furthermore, in the future, it is expected that LEDs will be used in lighting devices that should be lit overnight, such as general road or highway lighting and outdoor lighting, but considering these points and the problems of the traffic signals mentioned above, etc. Therefore, it is highly desirable to provide a traffic signal or lighting device that is not bulky, durable, and has a high waterproof function.

  Moreover, in order to solve such a problem, it is conceivable to seal the LED with a waterproof paint in order to provide a waterproof function to the LED used as the light emitting device. Inferior, limited use outdoors. Insulating coating agents for circuit boards are also commercially available, but this coating agent is inferior in heat resistance in addition to UV-decomposability, for example, it cannot withstand heat generation when used in lighting devices. There is. Further, although this coating agent has water resistance, it is poor in oil resistance, so it is easily contaminated.

  When the conventional technology is specifically examined, it is not for imparting a waterproof function to the LED, but Patent Document 1 discloses a water-based coating film waterproof for imparting waterproof properties to buildings such as a rooftop, a veranda, and a bathtub. Fluoropolymer-containing topcoat paint for materials is described. This water-based top coating composition comprises a coating film waterproofing layer comprising a vinyl acetate copolymer aqueous dispersion (component A) and a cementitious binder (component B), component A, a fluoropolymer dispersion (component C), and A composite waterproof layer having a paint film layer made of a pigment. However, in the case of this top coat, the desired effect cannot be achieved with only the paint film layer, and since an aqueous dispersion of a fluoropolymer is used, it is difficult to achieve the effect by moisture such as LED. It is not suitable for those whose performance can be degraded.

  Moreover, although it is not for giving a waterproof function to LED similarly, in patent documents 2 and 3, in order to express waterproofness in baking paint and other paints, the fluorine-containing copolymer which can be dissolved in an organic solvent is used. The use is described. However, in the case of these fluorine-containing copolymers, it is necessary to use a reaction catalyst together in order to obtain a coating film strength, so that not only the preparation of the paint becomes complicated, but also the reaction catalyst used in combination is an electric circuit. For example, it cannot be used for insulation purposes such as an electric circuit.

  Further, Patent Document 4 describes a liquid water-repellent paint characterized by comprising low molecular weight ethylene tetrafluoride resin particles and a binder resin, which are useful for painting automobile bodies, tableware, and the like. However, the coating film of this paint provides water repellency, but cannot guarantee waterproofness. Therefore, further improvement is required for outdoor use under harsh conditions.

  Furthermore, Patent Document 5 is not for providing a waterproof function to an LED, but in an EL light emitting device in which a light emitting part is sealed with a protective layer, the protective layer is coated over the entire circumference of the light emitting part. An EL light-emitting element comprising a waterproof coat layer made of a fluorine-based monomer and a waterproof film layer made of Teflon (registered trademark) or a silicon tube covering the waterproof coat layer is described. However, since the waterproof coating layer must be formed from a fluorine-based monomer, it is difficult to handle the raw materials during film formation, and the film formation process is complicated and complicated because the protective layer itself has a two-layer structure. .

Japanese Patent Laid-Open No. 6-116531 (abstract, claims, paragraphs 0022 and 0042) JP-A-57-34107 (Claims) JP-A-57-34108 (Claims) JP-A-8-217993 (abstract, claims, paragraph 0018) JP-A-5-152067 (abstract, claims)

  In view of the above-mentioned problems in the conventional technology, the object of the present invention is to seal conductive parts such as wiring, electrical contacts, electric wires, etc., and is not bulky, durable, and has a high waterproof function. An object of the present invention is to provide a coating composition excellent in water resistance, insulation and UV-decomposition resistance, which is useful for providing a traffic signal and a lighting device.

  Another object of the present invention is to provide articles in which the coating composition of the present invention is applied to seal conductive parts such as wires, electrical contacts, and electric wires, particularly articles used mainly outdoors, such as outdoor advertising devices, traffic signals, etc. It is to provide LED devices and other electronic devices such as a device, an electric light display device, and a road sign device.

  These and other objects of the present invention will be readily understood from the following detailed description.

  In one aspect, the present invention resides in a coating composition which is substantially composed of a fluoropolymer soluble in a solvent and a solvent in which the fluoropolymer is dissolved. The coating composition of the present invention can be preferably formed into a film by application to obtain a coating (coating film) having a predetermined thickness, and the application at that time depends on the performance of the obtained coating film. It may be a two-time coating or two or more over-coatings.

  In another aspect of the present invention, there is provided an article comprising the article and a coating layer formed from the coating composition of the present invention in which at least a conductive portion contained in the article is sealed. is there. The conductive portion of the article is typically exposed from the article before being sealed with the coating composition of the present invention.

Furthermore, the present invention provides
An LED device including one or more LED elements, wherein the LED elements and the conductive parts connected to the LED elements are sealed with a coating layer formed from at least the coating composition of the present invention. LED device,
A flexible circuit board on which a functional element is surface-mounted, wherein the functional element of the circuit board and a conductive portion connected to the functional element are formed from at least the coating composition of the present invention,
An electronic device equipped with one or more functional elements, wherein the functional elements of the electronic device and the conductive parts connected to the functional elements are sealed with at least a coating layer formed from the coating composition of the present invention Electronic devices,
A coated electric wire in which the exposed electric wire is sealed with a coating layer formed from at least the coating composition of the present invention;
There are others.

  Here, the “conductive portion”, when used in this specification, can be any electrical connection used to construct the article of the present invention, as can be easily understood from the following description. Includes means. Examples of suitable electrical connection means are not limited to those listed below, but can include electrical contacts such as electrical circuits, electrical wiring, conductor wires, flip chips, bumps, and the like. In the present invention, an antenna (antenna) is also defined as a “conductive portion”.

  In addition, the “functional element”, when used in the present specification, includes any part, component, or the like that can function actively or passively in an electronic device or other apparatus. Typical examples of active elements are not limited to those listed below, but light emitting elements such as LED chips, semiconductor elements such as IC chips and LSI chips, capacitors (capacitors), reactors, inductors, resistors Others can be mentioned.

  According to the present invention, a sealing layer (referred to as a “coating layer” in the present invention) can be easily formed when a conductive portion such as an electric circuit, electric wiring, electric contact, or electric wire is sealed. Furthermore, to provide a coating composition capable of imparting excellent water resistance, insulation, durability, particularly UV-decomposability, etc. to the resulting sealed article due to the physical properties of the coating layer. Can do.

  In addition, since this coating composition is obtained by dissolving a fluoropolymer in a solvent, it is not only easy to prepare, but also can be applied by a simple application means such as brush coating or dip coating. Therefore, this coating composition can be easily applied to a medium having surface irregularities such as a circuit board on which LED chips are surface-mounted or a semiconductor substrate on which LSI chips are mounted. A coating film having an arbitrary thickness can be formed by changing the above.

  Furthermore, in the case of an LED device, for example, the type of light emission can be arbitrarily adjusted by adjusting the thickness of the coating film. For example, since the coating composition is inherently transparent, when the coating layer is formed as a thin film or formed by a single coating, direct light can generally be emitted from the coating layer. In contrast, when the coating layer is formed as a thick film or formed by a plurality of coatings, generally diffused light can be emitted. In particular, LEDs are point light sources that are difficult to use for illumination as they are, but by forming the coating composition of the present invention as a multilayer coating layer, water resistance and outdoor weather resistance are improved and a light diffusion effect is realized. Can lead to lighting applications.

  Furthermore, since the resulting coating layer has excellent water resistance, insulation, durability, particularly UV-decomposability, various articles utilizing these excellent characteristics, such as outdoor advertising equipment, traffic, etc. LED devices such as a signal device, an electric light display device, and a road sign device, other electronic devices, a lighting device, a covered electric wire, and the like can be provided. Even if these articles are exposed to harsh conditions outdoors such as ultraviolet rays and wind and rain for a long period of time, they can stably maintain their excellent characteristics for a long period of time. For example, the articles of the present invention will typically be able to continue to be used for about 10 years without degradation or breakage of properties. Of course, since the coating composition of the present invention is based on a fluoropolymer, other good characteristics derived from the fluoropolymer, such as heat resistance and oil resistance (contamination resistance), should be reflected in the resulting article. Can do.

  In addition, the article of the present invention has a very excellent water resistance (noting the use in water), as defined by the JIS protection class according to Japanese Industrial Standard C0920 (equivalent to IEC 60529), 7 grade (waterproof type). Or more; it can be used under conditions that are close to underwater use because it has a level that does not allow water to enter if it is immersed in water at a depth of 15 cm to 1 m for 30 minutes. It becomes. For example, in a device that requires a direct current power supply such as an LED, resistance to water, that is, water resistance, is more important than conventional light emitting devices (bulb, fluorescent lamp) that require an alternating current power supply. This is because when an AC power supply is used, water is electrolyzed and oxygen and hydrogen are not generated in large quantities even if the insulation is broken to some extent by water. On the other hand, when a DC power supply is used, oxygen and hydrogen may be generated due to the presence of water even under application of a low voltage that can light the LED. Wirings such as copper, lead, and tin that are used tend to ionize and dissolve in water. However, since the coating composition of the present invention is remarkably excellent in water resistance, it can be applied to, for example, an LED, and the LED can be exposed outdoors, where water is easily applied, where the humidity is high, and condensation may occur. However, even if it is disposed in a place or the like, the LED is not deteriorated or unusable. In addition, the durability of the coating composition of the present invention and the special UV decomposition resistance are added to these characteristics, so that future market expansion is expected not only for LEDs but also for other articles of the present invention. it can.

  This invention exists in the articles | goods which apply | coated this and apply | coated it and sealed electrically conductive parts, such as a wiring, an electrical contact, and an electric wire, for example, an LED apparatus, various electronic devices, an antenna, etc. Hereinafter, the present invention will be described with respect to preferred embodiments thereof.

  A first aspect of the present invention resides in a coating composition which is substantially composed of a fluoropolymer soluble in a solvent and a solvent in which the fluoropolymer is dissolved. The fluoropolymer used as the main component in the present invention can exhibit various characteristics useful for the practice of the present invention, derived from its molecular structure, fluorine atoms contained in the molecule, and the like. The fluoropolymer is, for example, substantially transparent and does not adversely affect light transmission. In addition, the fluoropolymer has water resistance, insulation, durability including ultraviolet decomposition resistance, heat resistance, oil resistance (contamination resistance) and the like as characteristics unique to the polymer. Further, since the fluoropolymer of the present invention can be easily dissolved in a solvent, it can be easily applied by coating. In particular, since the fluoropolymer of the present invention does not need to be dissolved in a solvent at a high temperature, not only the handleability is remarkably improved, but the use of the fluoropolymer is expanded. In addition, in the conventional technology, in order to form a fluororesin coating, treatments such as adding a reaction catalyst and a crosslinking agent to the coating composition to increase the film strength or introducing a crosslinked structure are included. Although necessary, in the practice of the present invention, it is not necessary to incorporate special additives that can cause or participate in the reaction with the fluoropolymer.

  In the practice of the present invention, the fluoropolymer is not particularly limited as long as it has excellent characteristics as described above and is sufficiently exhibited in a coating composition or article that can obtain these characteristics. Including a wide range of fluororesins and fluororubbers. Also, the molecular weight of the fluoropolymer can be varied within a wide range, but is usually about 10,000 or more. The molecular weight of the fluoropolymer is preferably in the range of about 50,000 to about 200,000, more preferably in the range of about 50,000 to about 150,000. This is because when the molecular weight of the fluoropolymer is such a high molecular weight, the above-described characteristics are more favorably expressed.

  The fluoropolymers that can be used in the practice of the present invention are not limited to those listed below, but include fluoropolymers such as FEVE, PVDF (polyvinylidene fluoride), and THV. These fluoropolymers may be used alone or in combination of two or more.

  The FEVE-based fluoropolymer is a fluorine-containing copolymer containing, for example, fluoroolefin, cyclohexyl vinyl ether, alkyl vinyl ether and hydroxyalkyl vinyl ether as essential components. In such a copolymer, fluoroolefin, cyclohexyl vinyl ether, alkyl vinyl ether and hydroxyalkyl vinyl ether are 40 to 60 mol%, 5 to 45 mol%, 3 to 15 mol% and 0 to 30 mol%, respectively. Perfluoroolefins, in particular chlorotrifluoroethylene or tetrafluoroethylene, are used as the fluoroolefin. A fluorine-containing copolymer containing fluoroolefin, cyclohexyl vinyl ether, and glycidyl vinyl ether as essential constituent components is also an example of the FEVE fluoropolymer.

  When the PVDF fluoropolymer is a rubber (elastomer) system, it is composed of, for example, a fluororubber composed of a copolymer of vinylidene fluoride, tetrafluoroethylene and propylene, or a copolymer of vinylidene fluoride and hexafluoropropylene. Fluororubber, vinylidene fluoride, fluorinated rubber made of a copolymer of hexafluoropropylene and tetrafluoroethylene are included. Moreover, when it is a resin system soluble in a solvent, the PVDF polymer includes a vinylidene fluoride polymer, a vinylidene fluoride tetrafluoroethylene copolymer, and the like.

  Particularly useful fluoropolymers for the practice of the present invention are THV-based fluoropolymers, particularly multi-component fluoropolymers comprising at least hexafluoropropylene (HFP) and vinylidene fluoride (VdF). Such multi-component fluoropolymers typically include binary fluoropolymers composed of hexafluoropropylene (HFP) and vinylidene fluoride (VdF), tetrafluoroethylene (TFE), hexafluoropropylene (HFP) and vinylidene fluoride. It is a ternary fluoropolymer composed of a ride (VdF). Such a THV-based fluoropolymer is particularly easily soluble in a solvent, and is not only excellent in the above-mentioned characteristics such as water resistance, insulation properties, and UV degradation resistance, but also has a rough surface such as a circuit board. In addition, it can be applied by a simple method such as brushing or dipping, and a thick coating can be easily formed by repeated coating.

  In the binary or ternary fluoropolymer described above, the composition ratio of TFE, HFP and VdF of the fluoropolymer can be varied within a wide range. However, when a fluoropolymer is used for the purpose of sealing an article, it is desired to have good fluidity, good workability, and low permeability such as moisture. Those having crystallinity and melting point are preferred. For example, when used in an LED, light transmittance is also important in order to maintain the intensity of light emitted from the LED. From this point of view, a fluoropolymer containing about 36 to 72% by weight of TFE, about 0 to 56% by weight of HFP, and about 30 to 65% by weight of VdF is optimal. When such a composition ratio is deviated and the content of TFE increases, the color becomes milky white and the transparency decreases. In addition, the fluoropolymer having such an optimal composition ratio maintains chemical resistance close to that of PTFE, and has a low material permeability with a crystallinity of about 30% that cannot be obtained with fluororubber, Furthermore, there is an advantage of having flexibility. That is, since such a fluoropolymer has flexibility, for example, when it is applied to a flexible circuit board, it can easily follow the deformation and does not generate defects such as cracks. And can be advantageously used in the manufacture of electronic devices in which the arrangement of components and the like is complicated.

  For reference, a THV fluoropolymer comprising a composition ratio of tetrafluoroethylene (TFE) 36 to 72% by weight, hexafluoropropylene (HFP) 0 to 56% by weight, vinylidene fluoride (VdF) 8 to 45% by weight, A comparison of characteristics with general-purpose fluororesins is as follows.

Note) Evaluation criteria: Excellent>Good>Yes> No PTFE: Polytetrafluoroethylene PFA: Perfluoroalkyl-modified PTFE
FEP: Copolymer of tetrafluoroethylene and hexafluoropropylene PVdF: Polyvinylidene fluoride ETFE: Copolymer of ethylene and tetrafluoroethylene

THV-based fluoropolymers are commercially available, for example, as THV series from Dyneon. Examples of THV currently available include THV220, THV415, THV500, and the like. In the present invention, THV220 is particularly useful, and its characteristics include, for example, a melting point of 122 ° C., a glass transition point of 5 ° C., flame retardancy of V-0 (according to UL-94), and water permeability of 17. The refractive index is 7 g / m ² · 24H and the refractive index is 1.36. The various properties of these THV-based fluoropolymers are described in detail in the technical data of Dyneon.

  The coating composition of the present invention is obtained by dissolving an appropriate amount of the above-described fluoropolymer in a solvent. The solvent used in the practice of the present invention is not particularly limited as long as the fluoropolymer can be easily dissolved and the properties of the resulting coating composition and article are not adversely affected. Suitable solvents are ketone solvents, ester solvents, furan solvents, polar solvents and the like. These solvents may be used alone or in combination of any two or more solvents.

  Examples of usable solvents include, for example, acetone (dimethyl ketone), MEK (methyl ethyl ketone), diethyl ketone, MIBK (methyl isobutyl ketone), and the like. Examples of ester solvents include methyl acetate, ethyl acetate, and butyl acetate. Examples of the furan solvent include THF (terolahydrofuran). Examples of the polar solvent include NMP (N-methyl-2-pyrrolidone). These solvents are particularly suitable for dissolving a THV fluoropolymer.

  Further, for example, as a solvent suitable for dissolving the PVDF-based fluoropolymer, for example, NMP (N-methyl-2-pyrrolidone), DMAC (dimethylacetamide), DMSO (dimethylsulfoxide), DMF (N, N-dimethylformamide) and the like Examples include polar solvents and mixed solvents of butyl acetate, MIBK (methyl isobutyl ketone) and toluene.

  In dissolving the fluoropolymer in these solvents, the amount of the fluoropolymer can be varied within a wide range depending on the type of the fluoropolymer and the solvent, the details of the coating composition, and the like. Usually, the fluoropolymer can be used in an amount of up to about 25% by weight, preferably about 5-20% by weight, more preferably, based on the total amount of the coating composition. Can be used in an amount of about 10-15% by weight. When the amount of the fluoropolymer used is less than 1% by weight, not only a coating solution having a viscosity suitable for coating cannot be obtained, but also various properties derived from the fluoropolymer can be obtained even if a coating film is obtained. The film cannot be presented. On the other hand, if the amount of the fluoropolymer used exceeds 20% by weight, not only a coating solution having a viscosity suitable for coating can be obtained, but even if a coating film is obtained, the strength and other properties are inferior. You can only get things.

  The coating composition of the present invention consists essentially of two components, a fluoropolymer and a solvent, but, if necessary, assists in the preparation of the resulting coating composition or provides additional properties to the resulting composition. In order to impart the above, an additive generally used in the preparation of a fluoropolymer solution may be contained. Examples of suitable additives include surfactants, coloring materials, and light diffusing agents.

  The coating composition of the present invention can be easily dissolved simply by adding a fluoropolymer and optional additives to a solvent and stirring. Further, since the obtained coating solution has an appropriate viscosity, it can be directly applied to the surface of the article to be applied using a conventional technique such as brush coating, dip coating, or spray coating. . Moreover, depending on the case, it may be dripped at a predetermined site | part by techniques, such as potting, and a sealing part may be formed. The coating solution may be applied once or may be applied two or more times depending on the properties required for the coating film. After the application is completed, the obtained coating film is dried and cured. The drying operation may be left at room temperature, but if necessary, drying may be accelerated using a heater or oven. .

  The thickness of the coating after drying, that is, the thickness of the coating layer (or sealing layer) covering the surface of the article varies depending on the coating amount and the number of coatings of the coating solution. In the case of the present invention, the thickness of the covering layer is usually at least about 10 μm. Such a thin coating layer can be obtained by a single application of the coating solution, and exhibits excellent light transmittance while exhibiting water resistance and the like. The thickness of the coating layer increases as the number of times the coating solution is applied, and as a result, white turbidity resulting from the multilayer structure occurs, and light from the light source can be diffused. The thickness of the coating layer is preferably about 50 μm or more, and preferably in the range of about 60 to 100 μm when light is not diffused.

  The coating composition of the present invention has remarkable properties such as light transmission or light diffusivity, water resistance, insulation, UV degradation resistance, solution applicability and the like. It can be used to form layers, sealing layers and the like. A particularly suitable article is an article provided with a portion to be formed with a covering layer, a sealing layer, or the like, typically a conductive portion, in a surface region or an exposed portion. That is, the coating composition of the present invention can be applied to an article and used to at least seal a conductive part contained in the article. Since exposed conductive parts (such as electrical circuits, wiring, and antennas as described above) can be protected from moisture, ultraviolet rays, and other adverse effects, the characteristics of the conductive parts and the articles equipped with them can be maintained stably over a long period of time. In addition, since sufficient water resistance and the like can be ensured with only the coating composition, the use of a housing, a hood, etc. can be eliminated, and the size of the article can be reduced.

The present invention also resides in an article comprising the article and a coating layer formed from the coating composition of the present invention in which at least the conductive portion contained in the article is sealed. Articles according to the present invention may include a wide range of articles with conductive portions, typical examples of which are not limited to those listed below,
An LED device, in which the LED element of the device and the conductive portion connected to the LED element are sealed with at least the coating layer of the present invention,
A rigid or flexible circuit board (also referred to as a printed wiring board) on which a functional element is surface-mounted, and at least the functional element of the circuit board and the conductive portion connected to the functional element are sealed with the coating layer of the present invention What has been
An electronic device equipped with a functional element, in which the functional element of the device and the conductive portion connected to the functional element are sealed with at least the coating layer of the present invention,
A covered electric wire, in which the exposed electric wire is sealed with at least the coating layer of the present invention, including those covered with the coating layer of the present invention, such as an antenna.

  More specifically, the application is not limited to those listed below, but the LED device is, for example, a traffic signal (for example, a road signal, a railway signal, a construction sign with a signal lamp, etc.), an electric display board (for example, Elevating type large-sized electric light display board, news board, vehicle-mounted sign, ring light, etc.), road sign (direction board, delta flash, traffic jam display board, tunnel driving guidance light, etc.) and outdoor advertising media (eg, large LED TV, advertising light) , Pole signs, internally illuminated signboards, channel letters, edge lights, etc.), in-vehicle lights, and the like.

  The circuit board is a rigid printed board made of, for example, paper phenol resin, glass epoxy resin, fluororesin (PTFE, etc.), or a flexible printed board made of polyimide resin or hydrocarbon resin (PE, PP, etc.). In addition, the LED chip or the semiconductor chip mounted on the surface is included. As a supplementary explanation, in a flexible printed circuit board, the base material is usually made of a flexible film, such as an acrylic resin, a polyester resin, a polyurethane resin, a polyvinyl chloride resin, a hydrocarbon resin, etc. in addition to a polyimide resin. Can be formed. In addition, the conductive portions such as wirings, circuits, and contacts on the base material can be formed in an arbitrary pattern by a method similar to that generally used for manufacturing a printed circuit board. For example, a wiring pattern layer such as a wiring can be formed from a conductive metal such as copper, nickel, gold, silver, aluminum or an alloy thereof using a technique such as plating, vapor deposition, or ink jet printing. Moreover, after affixing a conductor film on the whole surface of a film base material, you may form a wiring pattern layer by selectively etching it. If necessary, the wiring pattern layer may be formed using a technique such as soldering.

  1 to 3 each show an example of a linear light including a circuit board on which an LED chip is mounted. In addition, in the top view (A) of each drawing, the coating layer 5 is shown with an oblique line in order to help understanding the arrangement state.

  FIG. 1 shows a linear light in which an LED chip 3 is mounted on the surface of a circuit board 1 made of glass epoxy resin. The LED chip 3 can emit white light. The copper wiring 2 is exposed on the surface of the circuit board 1, and the covered lead wire 6 is connected to this and fixed with the solder 4. The exposed wiring 2, the connecting portion between the wiring 2 and the lead wire 6, and the LED chip 3 are sealed with a coating layer 5 so as to cover the whole. The coating layer 5 can be easily formed by spot-dropping and curing the coating composition of the present invention by a drop method. In the illustrated example, the coating composition of the present invention is applied only to the portion of the surface of the circuit board 1 that must be covered at a minimum. The adhesion of the coating composition to the circuit board 1 is very good, and the coating layer 5 does not peel off during use.

  FIG. 2 shows a modification of the circuit board 1 shown in FIG. In the case of the illustrated circuit board 1, the application area of the coating composition of the present invention is enlarged and spreads over the entire surface of the circuit board 1 on which the LED chip 3 is mounted. In the case of this example, the coating composition can be applied, for example, by spray application (spray method). By covering the entire surface of the circuit board 1 with the coating composition, the water resistance, insulation, durability and the like of the circuit board 1 can be further improved. The adhesion of the coating composition to the circuit board 1 is very good, and the coating layer 5 does not peel off during use.

  FIG. 3 shows another modification of the circuit board 1 shown in FIG. In the case of the illustrated circuit board 1, the coating composition of the present invention is uniformly applied to the entire surface of the circuit board 1 to form the coating layer 5. In this example, the coating composition can be applied by, for example, dip coating (dip method). By coating the entire surface of the circuit board 1 with the coating composition, the water resistance, insulation, durability and the like of the circuit board 1 can be further improved, and the usage of the circuit board 1 can be further expanded. The adhesion of the coating composition to the circuit board 1 is very good, and the coating layer 5 does not peel off during use.

  In addition, although not shown, the coating composition of the present invention can also be used to protect or seal the exposed portion of the wire. That is, the electric wire is usually provided in a state of being covered with a vinyl chloride resin or the like, and the coating is peeled off at a necessary place and the internal electric wire is exposed, but the exposed electric wire is externally attached. In order to protect against the influence, the exposed electric wire can be coated and protected with the coating composition of the present invention. Similarly, when the coating composition of the present invention is coated to protect the surface of various antennas (aerials), the antenna must be used for a long period of time without any defects such as corrosion. Can do.

  Subsequently, the present invention will be described with reference to examples thereof. Needless to say, the present invention is not limited to these examples.

Example 1
Preparation of Test Circuit Board and Evaluation of Insulation (1) Glass epoxy resin and (2) paper phenol resin having a width of 47 mm, a length of 72 mm, and a thickness of 1.5 mm were prepared as the base material 1. As shown in FIG. 4, two copper wirings (width 1.5 mm × length 63 mm × thickness 0.05 mm) 2 are partially solder-plated on the surface of the substrate 1 and etched. Is formed by. A lead wire 6 was attached to one end face of each copper wiring 2 with lead solder 4. A test circuit board (comparative example) before mounting the LED chip was obtained.

  Next, in the test circuit board (comparative example), the coating composition 5 of the present invention is spray-applied so as to cover substantially the entire copper wiring 2 (see FIG. 4), and is cured by drying. It was. The coating composition used in this example is obtained by dissolving 10 g of a fluororesin (trade name “THV220A”, manufactured by Dinion) in 40 g of ethyl acetate. A test circuit board (example of the present invention) in which the two copper wirings 2 were covered with a coating layer 5 having a thickness of 100 μm was obtained.

  Each test circuit board was placed in a beaker containing water and submerged to a position indicated by W in FIG. After maintaining the immersion state for 60 minutes or more, the resistance between two unshorted wires on the circuit board was measured in water. The measurement of resistance was performed using a measuring instrument conforming to the safety standard of IEC61010, which is usually used for testing electrical wiring, and “KEW MATE MODEL 2000” (trade name) manufactured by Kyoritsu Electric Instruments Co., Ltd. Measurement results as shown in Table 1 below were obtained.

  As can be understood from the measurement results shown in Table 1 above, when a coating layer is formed by applying the coating composition of the present invention, a sufficient insulating property can be secured, as in the comparative example. When the coating layer is not formed, insulation cannot be obtained.

  Further, assuming that the circuit board for testing is actually used, a current of about 5 V, which is the same as the LED power supply, was passed through the lead wire underwater. Oxygen and hydrogen bubbles began to develop after the passage. When 10 minutes or more passed, it was confirmed by visual observation that the copper wiring, solder, etc. of the substrate were dissolved, so the evaluation test was stopped at that time. In the case of the example of the present invention, such a problem was not recognized.

Example 2
Production of LED-mounted circuit board and lighting test After producing a test circuit board (comparative example) as described in Example 1, an LED chip (trade name “E1S02” was straddled across two copper wirings 2. −3G ”(manufactured by Toyoda Gosei Co., Ltd.) 3 and fixed with lead solder 4. After the LED chip 3 was mounted, the coating composition 5 of the present invention was sprayed and cured by drying so as to cover substantially the entire copper wiring 2 of the circuit board (see FIG. 4). As in Example 1, the coating composition used in this example was prepared by dissolving 10 g of a fluoropolymer (trade name “THV220A”, manufactured by Dyneon) in 40 g of ethyl acetate. An LED-mounted circuit board (example of the present invention) in which two copper wirings 2 were covered with a coating layer 5 having a thickness of 100 μm was obtained.

  The LED-mounted circuit board was placed in a beaker containing water and submerged to a position indicated by W in FIG. The circuit board was submerged and energized, and the LED was kept on for 8 hours or more. The lighting continued without interruption, and no oxygen or hydrogen was generated during that time. Further, as shown in FIG. 3, the coating composition of the present invention is dip-coated on an LED linear light (trade name “White LED board unit NP-00014”, manufactured by Shibasaki), and a circuit board having an average film thickness of 70 μm is formed at the lower end. Was energized in a state of being submerged 1 m from the water surface, and the LED was kept on for 2 hours or more. From this, it can be seen that the LED-mounted circuit board of this example has a water resistance of 7 or more (waterproof type) as defined by JIS protection class (according to Japanese Industrial Standard C0920).

Example 3
Production of LED-mounted circuit board and lighting test An LED-mounted circuit board was produced by the method described in Example 2. However, in the case of this example, the coating composition obtained by dissolving a fluororesin (trade name “THV220A”) in ethyl acetate was applied repeatedly by brushing instead of spray coating on the circuit board. An LED-mounted circuit board (example of the present invention) in which the two copper wirings 2 were covered with a coating layer 5 having a thickness of 500 μm was obtained.

  The LED-mounted circuit board was placed in a beaker containing water and submerged to a position indicated by W in FIG. The circuit board was submerged and energized, and the LED was kept on for 8 hours or more. The light from the LED changed from clear light to diffused light, but lighting was continued without interruption, and no generation of oxygen or hydrogen was observed during that time.

It is the top view (A) and sectional drawing (B) which showed an example of the circuit board of this invention carrying an LED chip. It is the top view (A) and sectional drawing (B) which showed another example of the circuit board of this invention carrying an LED chip. It is the top view (A) and sectional drawing (B) which showed another example of the circuit board of this invention carrying an LED chip. It is a perspective view of the LED chip mounting circuit board produced in the Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Circuit board 2 Wiring 3 LED chip 4 Solder 5 Coating layer 6 Lead wire

Claims (12)

  A coating composition comprising a fluoropolymer that is soluble in a solvent and has a molecular weight of 10,000 or more, and a solvent in which the fluoropolymer is dissolved.   The coating composition of claim 1, which does not contain additives that can cause or participate in the reaction with the fluoropolymer.   The coating composition according to claim 1 or 2, wherein the fluoropolymer is a FEVE fluoropolymer, a PVDF fluoropolymer, a THV fluoropolymer, or a mixture thereof.   The coating composition according to claim 1, wherein the fluoropolymer is a multi-component fluoropolymer including at least hexafluoropropylene (HFP) and vinylidene fluoride (VdF).   The coating composition according to claim 1, wherein the fluoropolymer is composed of a ternary fluoropolymer composed of tetrafluoroethylene (TFE), hexafluoropropylene (HFP), and vinylidene fluoride (VdF). object.   The coating composition according to any one of claims 1 to 5, which is applied to an article and used to at least seal a conductive part contained in the article.   An article comprising the article and a coating layer formed from the coating composition according to any one of claims 1 to 5, wherein at least a conductive portion contained in the article is sealed.   The article according to claim 7, wherein the conductive portion is a portion exposed from the article.   The article according to claim 7 or 8, wherein the article is an LED device, and an LED element of the device and a conductive portion connected to the LED element are sealed with at least the covering layer.   The article is a flexible circuit board on which a functional element is surface-mounted, and the functional element of the circuit board and a conductive portion connected to the functional element are sealed with at least the covering layer. The article according to 8.   The said article | item is an electronic device carrying a functional element, The functional element of this device and the electroconductive part connected to this functional element are sealed by the said coating layer at least. Goods.   The article according to claim 7 or 8, wherein the article is a covered electric wire or antenna, and an exposed metal portion of the electric wire or antenna is sealed with at least the covering layer.

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