JP6517086B2 - Thermal radiation coating, light emitting diode (LED) illumination having the same, heat sink, back sheet for solar cell module - Google Patents

Description

The present invention has a high heat radiation property, efficiently discharged to the outside of the system the heat generated as the infrared heat radiation coating film and a light emitting diode having the same (LED) lighting, heat sink, to the back sheet for a solar cell module.

  As known for black body radiation, thermal radiation is a phenomenon in which thermal energy is emitted from an object as electromagnetic waves, in particular as infrared radiation, from the object. On the other hand, the phenomenon in which an object is warmed by electromagnetic waves emitted from a heat source is called absorption of thermal energy. Thermal radiation and thermal absorption reverse the direction of energy conversion, which follows the second law of thermodynamics. In order to make thermal radiation proceed advantageously, absorption of electromagnetic waves in a wide range of wavelengths and increase of surface area can be mentioned. However, the heat generation temperature of LED (light emitting diode) lighting, electronic parts and the like is about 70 to 200 ° C., and this heat is radiated in the infrared region, so it is not necessary to be a complete black body. Ceramics have been widely used since they have the characteristic of selectively emitting heat in the infrared region (see Patent Documents 1 to 3).

Japanese Patent Application Laid-Open No. 3-136807 Japanese Patent Application Laid-Open No. 10-279845 JP 2004-43612 A

However, in the prior art, it has been difficult in some cases to achieve both heat radiation and coating film adhesion.
An object of the present invention is to provide a thermally radiative paint, a light emitting diode (LED) illumination coated with the same, a heat sink, and a back sheet for a solar cell module, which can increase the emissivity in the infrared region and dissipate heat efficiently.

  As a result of investigations to solve the above problems, the present inventors use a specific ceramic, and further, by setting the compounding ratio of the ceramic powder (hereinafter also referred to as a ceramic) and the binder to a specific ratio, It has been found to enhance the radiation and the adhesion of the coating.

  The present invention comprises (a) ceramic powder having an average particle diameter of 0.1 to 50 μm and containing zinc oxide powder or titanium oxide powder or both, and (b) a binder which is a thermosetting resin or colloidal silica. The present invention relates to a thermally radioactive paint containing 30 to 100 parts by mass of zinc oxide powder and / or titanium oxide powder or the total of 100 parts by mass of the binder.

  In the present invention, (b) the binder is a phenol resin, alkyd resin, melamine urea resin, epoxy resin, polyurethane resin, silicone resin, vinyl acetate resin, acrylic resin, chlorinated rubber resin, vinyl chloride resin, fluorocarbon resin, cellulose It relates to the above-mentioned heat-emitting paint which is at least one of gum and colloidal silica.

  The present invention also relates to the above-mentioned heat-emitting paint having an emissivity of 0.90 or more in a wavelength range of 2 to 22 μm.

  The present invention also relates to a light emitting diode (LED) illumination in which the above-mentioned thermal radiation paint is applied at an average film thickness of 1 to 50 μm.

  Further, the present invention relates to a heat sink to which the above-mentioned heat radiation paint is applied at an average film thickness of 1 to 50 μm.

  The present invention also relates to a back sheet for a solar cell module, which is coated with the above-mentioned heat-emitting paint at an average film thickness of 1 to 50 μm.

  According to the present invention, it has become possible to provide a thermally radiative paint capable of increasing the emissivity in the infrared region and efficiently dissipating heat, a light emitting diode (LED) illumination coated with the same, a heat sink, and a back sheet for solar cell module.

It is a schematic diagram which showed the measuring method of the temperature of the LED bulb which painted the paint. It is a schematic diagram showing the heat sink which painted the paint. It is the expanded view which showed the solar cell module backsheet which painted the paint.

Embodiments of the present invention will be described below.
The present invention comprises (a) ceramic powder having an average particle diameter of 0.1 to 50 μm and containing zinc oxide powder or titanium oxide powder or both, and (b) a binder which is a thermosetting resin or colloidal silica. And a thermal radioactive paint containing 30 to 100 parts by mass of a total of zinc oxide powder and / or titanium oxide powder with respect to 100 parts by mass of the binder.

  As the zinc oxide powder and the titanium oxide powder used in the present invention, conventionally known ones can be used without particular limitation. For example, commercially available 23-K (Haxui Tech Co., Ltd., zinc oxide), TIG R-900 (Dupont Co., Ltd., titanium oxide), JR-1000 (Taika Co., Ltd., titanium oxide), etc. are suitably used. be able to. In addition, other ceramic powders having heat radiation characteristics may be included, and conventionally known ones can be used without particular limitation. Hereinafter, ceramic powder is used as a generic term including zinc oxide powder and titanium oxide powder. Examples of other ceramic powders that can be used include powders of silicon oxide, zirconium oxide, magnesium oxide, iron oxide, copper oxide, nickel oxide, and cobalt oxide.

The average particle diameter of the particles of the zinc oxide powder and the titanium oxide powder in the present invention is 0.1 to 50 μm from the viewpoint of heat radiation, but is preferably 1 to 45 μm from the viewpoint of coating properties. The average particle diameter of the ceramic powder that can be used other than these is also preferably 0.1 to 50 μm, more preferably 1 to 45 μm. If the average particle size of the ceramic powder exceeds 50 μm, it penetrates a film of 50 μm recommended film thickness for efficient heat radiation, and there is a risk that the strength of the coating film, the adhesion strength with the object to be coated, and the adhesion decrease. is there. On the other hand, if the average particle size of the ceramic powder is less than 0.1 μm, the ceramic powder may be completely covered with the binder, which may reduce the emissivity of the surface of the coating of the heat radioactive paint. These ceramic powders may be used alone or in combination of two or more. It is possible to use titanium oxide which is excellent in far-infrared radiation property, silicon oxide, or zinc oxide which is also high in near-infrared range. It is.
The average particle size of the ceramic powder can be measured, for example, by a laser diffraction type particle size distribution measurement method or the like.

  The ceramic powder in the present invention may have pores. Also, pores may be formed by aggregation of primary particles of the ceramic powder. The emissivity tends to be improved by including a ceramic having pores. About this, the inventors of the present invention think that the emissivity can be enhanced by having the pores and floating on the surface of the coating film after coating and the surface area of the coating film of the thermal radiation coating material can be expanded. There is. In addition, it is considered that the emissivity inherent to the ceramic can be expressed by increasing the proportion of the ceramic powder on the surface and decreasing the proportion of the resin (binder).

  It is preferable that the thermal radiation coating material of this invention is 0.90 or more in the emissivity in a 2-22 micrometers wavelength range. In addition, in order to obtain emissivity (also expressed as heat emissivity), an emissivity measurement device TSS-5X (manufactured by Japan Sensor Co., Ltd., wavelength range 2 to 22 μm) is generally used, and the measurement is performed in an acrylic case Do. If the emissivity (heat emissivity) is less than 0.90, the heat dissipation effect may be insufficient for non-metals.

  As a binder used for this invention, a conventionally well-known thing can be used and it does not specifically limit, For example, emulsion resin, such as a synthetic resin and water-based emulsion resin, is mentioned. Synthetic resins include synthetic resins such as alkyd resin, amino alkyd resin, acrylic resin, phenol resin, urea resin, melamine resin, epoxy resin, polyurethane, polyvinyl chloride, polyvinyl acetate and the like, among which acrylic resin from the viewpoint of price Is preferred. Further, as the aqueous emulsion resin, there are a silicone acrylic emulsion, an acrylic emulsion, a urethane emulsion, a urethane acrylic emulsion and the like, and among them, a silicone acrylic emulsion is preferable from the viewpoint of dispersibility and heat resistance. Furthermore, the synthetic resin has good mechanical stability and preferably has a glass transition temperature (hereinafter abbreviated as Tg) of 0 to 70 ° C. If the temperature is less than 0 ° C., the adhesion is good but the coating is too soft, and the abrasion resistance, the stain resistance, the drying property and the coating strength are inferior. If the temperature exceeds 70 ° C., the addition of an excess of a film-forming agent, a marked increase in the viscosity of the coating, a crack due to a decrease in the flexibility of the coating will occur, and the water resistance of the coating tends to decrease. If the temperature is in the range of 0 to 70 ° C., the above-mentioned problems do not occur and a good coating film is obtained.

  Moreover, as for the average molecular weight (The weight average molecular weight of standard polystyrene conversion by gel permeation chromatography) of the synthetic resin used as a binder, 100,000-200,000 are preferable. If the average molecular weight is less than 100,000, the coating strength is too weak, and the coating tends to peel off and stain resistance tends to be poor. If it exceeds 200,000, the coating film strength and the stain resistance do not matter but the viscosity tends to be high. More preferably, it is 130,000 to 170,000. If the weight average molecular weight is in the above range, the above-mentioned problems do not occur, and a good coating film is obtained. In the case of an aqueous emulsion resin, the solid content concentration (hereinafter, abbreviated as NV) is preferably 43 to 62% by mass. If the amount is less than 43% by mass, the NV in the paint tends to be low and the drying property tends to be poor. If the amount is more than 62% by mass, the paint viscosity tends to increase and the crack resistance tends to decrease. 10-70 mass% is preferable with respect to a heat | fever radioactive coating material, as for the compounding quantity of binders, such as a synthetic resin and water-based emulsion resin, 20-60 mass% is more preferable, and 30-50 mass% is more preferable. If it is less than 10% by mass, the workability tends to be increased due to the increase in the viscosity of the coating, while if it exceeds 70% by mass, the drying property and the stainability tend to be inferior.

  Moreover, in the case of application to a high temperature region exceeding 200 ° C., in order to provide heat resistance, it is particularly preferable to include a thermosetting resin as a binder. Such thermosetting resins are commercially available, and can be synthesized by conventional methods. As a thermosetting resin, Preferably an epoxy resin is mentioned, YDCN-700-10, YSLV-80XY (made by Tohto Kasei Co., Ltd., a brand name), etc. are mentioned. As a curing agent for this resin, known curing agents that are usually used can be used. For example, bisphenols having two or more phenolic hydroxyl groups per molecule such as amines, polyamides, acid anhydrides, polysulfides, boron trifluoride, bisphenol A, bisphenol F, and bisphenol S, phenol novolac resins, bisphenol A Novolak resin or phenol resin such as cresol novolac resin may, for example, be mentioned. These may be used alone or in combinations of two or more. Such phenolic resins are commercially available and can be synthesized by conventional methods. As said commercially available phenol resin, for example, Mirex XLC series and Mirex XL series (above, Mitsui Chemical Co., Ltd. make, brand name), and HE-200C-10 (Nippon Air Water Co., Ltd. make, phenol resin, trade name) )).

  Moreover, the coating film after sintering by a sol-gel method using colloidal silica etc. as a binder can turn into a ceramic, and all the coating films can have high heat radiation and high heat resistance.

  The present invention comprises (a) ceramics having an average particle diameter of 0.1 to 50 μm and containing zinc oxide powder or titanium oxide powder or both, and (b) a binder, wherein 100 parts by mass of the component (b) On the other hand, it is a thermally radioactive paint containing 25 to 100 parts by mass of the component (a). Moreover, it is preferable that it is 30-100 mass parts ceramic (powder) containing one or both of the said oxide powder or a titanium oxide powder with respect to 100 mass parts of said (b) binders. Furthermore, it is preferable that it is 40-90 mass parts from a heat radiation viewpoint, and it is especially preferable that it is 50-85 mass parts from a coating film viewpoint. If the amount of the component (a) is less than 25 parts by mass, it may be buried in the binder and the heat radiation performance may be reduced. Moreover, when the said (a) component exceeds 100 mass parts, many irregular unevenness may appear on the coating-film surface, and an external appearance may be impaired.

  The heat-radiating paint used in the present invention may generally be produced by filling or kneading other components together with the above-mentioned components. As such components, there are a film forming aid, a plasticizer, a pigment, a silane coupling agent, a dispersant, an antifoaming agent and the like.

  As a coalescent agent, butyl carbitol acetate, butyl carbitol, butyl cellosolve, butyl cellosolve acetate, benzyl acetate, 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, 2,2,4-trimethyl 1,3-Pentanediol diisobutyrate, 2,2,4-trimethyl-1,3-pentanediol 2-ethylhexanoate isobutyrate, 2,2,4-trimethyl-1,3-pentanediol Di 2- Ethyl hexanoate, 2-ethylhexyl glycol, propylene glycol monobutyl ether and the like can be mentioned. The content of the film-forming aid is preferably 0.1 to 20% by mass, more preferably 0.5 to 10% by mass, and more preferably 1 to 5% by mass in the heat-radiating paint. Is more preferred. Here, if the content of the film-forming agent is less than 0.1% by mass, film formation at the time of coating tends not to be obtained, and if it exceeds 20% by mass, the film formation is good but the film drying is deteriorated. Tend.

As the plasticizer, phthalic acid esters such as dioctyl phthalate (DOP), phosphoric acid esters such as triethyl phosphate (TEP), tributyl phosphate (TBP), phenyl glycidyl ether (PGE), benzyl alcohol, acetyl citric acid based plasticizer, epoxy plasticizers, trimethylene Li Tsu preparative based plasticizers, and the like. As for the compounding quantity of a plasticizer, 0.5-5 mass% is preferable in a thermal radiation coating material, 1-4 mass% is more preferable, 1.5-2.5 mass% is more preferable. If it is less than 0.5% by mass, the flexibility at low temperature tends to be poor, while if it is more than 5% by mass, the drying property and the stainability tend to be inferior.

  As a silane coupling agent, various things are mentioned and it has functional groups, such as an epoxy group, a styryl group, methacryloxy group, an acryloxy group, an amino group, a ureido group, a chloropropyl group, a mercapto group, an isocyanate group, and a sulfide group. However, epoxy groups are preferred. The content of the silane coupling agent is preferably 0.01 to 5% by mass, more preferably 0.02 to 4% by mass, and more preferably 0.03 to 3% by mass in the heat emitting paint. More preferably, Here, when the content of the silane coupling agent is less than 0.01% by mass, the effect of improving the coating film strength and water resistance tends to be insufficient, and when it exceeds 5% by mass, the paint balance is lost, adhesion There is a tendency to decrease in strength, viscosity, crack resistance, etc. and to increase viscosity over time.

  As the dispersant, alkylamine salt of polycarboxylic acid, alkyl ammonium salt, alkylol aminoamide, polycarboxylic acid polyaminoamide, ammonium salt of acrylic copolymer, polycarboxylic acid sodium salt, polycarboxylic acid ammonium salt, polycarboxylic acid Examples thereof include carboxylic acid amino alcohol salts, polyaminoamide-based carboxylates, and polyaminoamide-based polar acid ester salts.

  As the antifoaming agent, modified silicone antifoaming agent, special silicone antifoaming agent, silicone antifoaming agent, silica antifoaming agent, silica silicone antifoaming agent, hydrophobic silica, hydrophobic silicone, wax, special Wax, polysiloxane and the like can be mentioned.

  The blending amount of the dispersant and the antifoaming agent is preferably 0.1 to 5% by mass, more preferably 0.3 to 4% by mass, and still more preferably 0.5 to 3% by mass, in the heat emitting paint. If the amount is less than 0.1% by mass, the dispersion and defoaming properties of the paint tend to be low. On the other hand, if it exceeds 5% by mass, the dispersion and defoaming properties are good, but at the time of coating, the surface of the coating film is likely to be repelled and the appearance of coconut skin.

  In the case of producing a paint using the heat-radiative paint of the present invention, the method for producing the paint is not particularly limited, but first, it is necessary to disperse the ceramic powder in a binder. As this method, usually, a binder and a ceramic powder are mixed with water or an organic solvent, and this mixture is dispersed and kneaded using various dispersion and kneading devices such as a three-roll, ball mill, sand mill, bead mill, kneader, etc. It can be carried out. In the case where the binder is an emulsion resin, water or an organic solvent is not necessarily required, and can be appropriately used as needed.

In addition, it is preferable to use the above-mentioned dispersant at the time of dispersing the ceramic, because the dispersibility and the dispersion stability of the pigment become good. Examples of the pigment include inorganic pigments such as zinc white, lead white, lithopone, titanium dioxide, ultramarine blue, potassium blue ferrocyanide, and carbon black, and organic pigments containing an azo compound or the like. It can be mentioned.
The dispersing agent is preferably used in an amount of 50 parts by mass or less with respect to 100 parts by mass of the pigment at the time of dispersion of the ceramic powder. Large particle size titanium dioxide, silica powder or silicate powder, and other components may be added at the time of pigment dispersion or may be added after dispersion. Similarly, the total amount of water or organic solvent may be used at the time of dispersing the ceramic powder, or a part of them may be added after the dispersion. However, it is preferable to use water and an organic solvent at least 50 parts by mass or more at the time of dispersion with respect to 100 parts by mass of the total amount of binder and ceramic powder at the time of dispersion. When the amount is less than 50 parts by mass, the viscosity at the time of dispersion is too high, and dispersion may be difficult particularly when dispersed by a ball mill, sand mill, bead mill or the like.

  There is no restriction | limiting in particular as a water or an organic solvent used at the time of dispersion | distribution, As a organic solvent, a ketone type, alcohol type, an aromatic type etc. are mentioned, for example. Specifically, acetone, methyl ethyl ketone, cyclohexane, ethylene glycol, propylene glycol, methyl alcohol, ethyl alcohol, isopropyl alcohol, n-butyl alcohol, benzene, toluene, xylene, ethyl lactate, ethyl acetate and the like can be mentioned. These may be used alone or in combination of two or more.

  However, the choice of water or organic solvent is appropriately determined in combination with other materials such as ceramics, dispersants, etc. In some cases, the heat radiation performance which is a feature of the present invention when using a certain organic solvent It is self-evident that the organic solvent can not be used in the system if it is out of a specific range. Therefore, the organic solvent to be used is not limited, but an organic solvent suitable for the system must be selected.

  Next, brush coating, spray coating and roll coater coating are preferable as the coating method of the heat radiation coating material thus obtained, but electrostatic coating, curtain coating, dipping method, electrodeposition coating are preferable depending on the object to be coated. Etc. are also applicable. Furthermore, after coating, as a method of drying to form a coating, methods such as natural drying and baking can be used, and it is appropriately selected depending on the coating properties and the like.

  Although it does not specifically limit regarding the average film thickness after coating of a heat | fever radiation coating material, It is preferable that it is 50 micrometers or less. If it exceeds 50 μm, the influence of the thermal resistance in the film can not be ignored, and heat may not be sufficiently transmitted to the surface of the coating, which may lower the heat radiation efficiency. The average film thickness is preferably 1 μm or more. If it is less than 1 μm, the heat radiation effect may not be sufficiently exhibited.

The system for coating the heat radiation paint is not particularly limited, but the invention can be applied to a heat sink for an LED light bulb (LED illumination) and a back chassis of a liquid crystal television. For example, a heat sink 2 made of Al can be mentioned. The coating method is carried out by the above method, and as shown in FIG. 2, it is preferable to coat a portion not in contact with the heat source. Generally, a metal has a very low emissivity, and heat radiation can not be expected to be dissipated, so that coating on a metal surface with a heat radiation paint is useful for heat dissipation.
Moreover, the effect of the present invention can be expected as long as it is a non-metallic object that is an emissivity lower than that of the coating film. For example, as shown in FIG. 3, a solar cell module backsheet can be mentioned. In addition, as a coating site | part is shown in FIG. 3, a back seat surface is preferable.
Moreover, it is preferable that the average film thickness of the heat | fever radiation coating apply | coated to appropriate site | parts, such as LED lighting, a heat sink, and a solar cell module back sheet, is 1-50 micrometers.

  Hereinafter, the present invention will be more specifically described by way of examples. However, the present invention is not limited to the following examples.

(Examples 1 to 6, Comparative Examples 1 to 3, Reference Example 1)
Table 1 and Table 2 show trade names and blending ratios (mass ratios). The components were stirred until uniform to obtain a paint.

Below, the detail of each component is shown.
23-K (trade name): manufactured by Hakusui Tech Co., Ltd., zinc oxide, average particle diameter 5.5 μm
TIG R-900 (trade name): DuPont Co., Ltd., titanium oxide, average particle size 0.2 μm
JR-1000 (trade name): manufactured by Tayca Corporation, titanium oxide, average particle diameter 1.0 μm
Primal AC-3001 (trade name): Rohm and Haas Japan Co., Ltd., acrylic Emar tion SN Dispersant Santo 5029 (trade name): San Nopco Co., Ltd., ammonium poly carboxylic acid CS16 (trade name): nitrogen oil Chemical Co., Ltd., 2,2,4-trimethyl-1,3-pentadiol isobutyrate Nopco 8034 (trade name): San Nopco Ltd., hydrophobic silica polyethylene glycol Adekasizer NRS-602 (trade name): Asahi Electrification industry Ltd. make, adipic acid diester KBM-403 (brand name): Shin-Etsu Chemical Co., Ltd. make, 3-glycidoxypropyl trimethoxysilane

(Evaluation)
The evaluation items shown below were evaluated using the paints obtained in Examples 1 to 6 and Comparative Examples 1 to 3.

[Preparation of sample plate for measuring thermal emissivity
The measurement sample of thermal emissivity was coated on a 1 mm thick aluminum plate with a desk coater and dried by heating at 80 ° C. for 30 minutes. The film thickness was made to be 40 μm after drying.

Thermal Emissivity
Thermal emissivity is a value representing the ability to release thermal energy as compared to a perfect black body. Further, according to Kirchhoff's law, heat radiation and heat absorption are equivalent, and the relationship of heat emissivity = heat absorptivity holds. In addition, since energy incident on an opaque substance is simultaneously reflected and absorbed, the relationship of reflectance + absorptivity (emissivity) = 1 holds. Therefore, the thermal emissivity can be determined indirectly by measuring the reflectance.
In order to obtain the thermal emissivity based on the above principle, an emissivity measurement device TSS-5X (manufactured by Japan Sensor Co., Ltd., wavelength range 2 to 22 μm) was used. Moreover, the measurement was performed in an acrylic case.

[Measurement of LED bulb temperature]
Using the paints obtained in Examples 1 to 6 and Comparative Examples 1 to 3, the surface of the heat sink 2 made of Al and the vicinity of the LED bulb 1 were sprayed with a film thickness of 25 μm and dried by heating at 80 ° C for 30 minutes. The temperature was measured at two points (measurement points) shown in FIG. 1 in the vicinity of the heat sink 2 and the LED bulb 1 coated with this paint. The temperature was measured at two points (measurement points) as shown in FIG. 1 with a polyimide tape in which a thermocouple was cut into 3 × 5 mm, and the temperatures before and one hour after lighting were measured. The temperature difference before and after the lighting was determined.

[Coating film adhesion test]
Using the paints obtained in Examples 1 to 6 and Comparative Examples 1 to 3, the paint is applied to a 1 mm thick aluminum plate with a desk coater and dried by heating at 80 ° C. for 30 minutes. The thickness of the coating was adjusted to 40 μm after drying. Only this coating film portion was cut parallel to both the vertical and horizontal directions at an interval of 2 mm, and a cut of 25 squares was made by 5 × 5. A cellophane tape (manufactured by Nichiban Co., Ltd.) was strongly pressed to the grid pattern portion and then peeled off to determine the presence or absence of peeling of the coating film. The test was carried out with 4 samples, and the case where the number of peeled pieces was less than 10 squares was marked ○, and the case of 10 squares or more was marked x.

In comparison with Comparative Examples 1 and 3, the emissivity is 0.90 or less when the ceramics is less than or contained in the above range, and the heat dissipation property is lowered, whereas all of the examples 1 to 6 have emissivity The temperature could also be reduced by more than 1.degree. C. by more than 0.90. Moreover, it turned out that coating film adhesiveness is favorable in comparison with the comparative example 2 that ceramics are in the said range.
Reference Example 1 is the case where no paint is applied.

1: LED bulb, 2: heat sink, 3: coating, 4: heat source, 5: cover glass, 6: filler, 7: cell, 8: tab wire, 9: back sheet.

Claims (5)

(A) A ceramic powder containing zinc oxide powder or titanium oxide powder or both with an average particle diameter of 1 to 50 μm, and (b) a binder, wherein zinc oxide powder or titanium oxide is used per 100 parts by mass of the binder powder or the sum of both comprises 30 to 100 parts by weight, the binder is formed from a resin emulsion der Ru thermal radiation coatings, thermal radiation coating film an average thickness is 1 to 50 [mu] m.   The heat radiation coating film according to claim 1, wherein the emissivity in a wavelength range of 2 to 22 μm is 0.90 or more.   A light emitting diode (LED) illumination comprising the thermally emissive coating according to claim 1 or 2.   A heat sink having the heat radiation coating film according to claim 1 or 2.   The solar cell module backsheet which has a heat radiation coating film of Claim 1 or 2.

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