JP5778962B2 - Foamed resin coated metal sheet and method for producing the same - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a foamed resin coated metal sheet having excellent vibration damping properties, bending workability, and coating film adhesion.

  Damping materials for absorbing vibrations at various parts are used in home appliances, office equipment, and moving bodies such as automobiles, and the demand for damping materials is great. Damping materials are important because they increase the product value by improving the quietness of the product. However, it is necessary to use damping materials for a large number of vibration parts, which causes high costs. . For this reason, the use of vibration materials is reduced or omitted by imparting vibration damping to the steel sheet itself used as the housing to suppress vibration of the entire product, thereby reducing costs and improving added value. Attempts have been made.

  The applicant of the present invention is also a foamed resin coating laminated metal plate in which a foamed resin coating film is laminated on the surface of the metal plate as a metal plate having vibration damping properties, An air bubble provides a coated metal sheet derived from a thermally expandable capsule or a chemical foaming agent (Patent Document 1).

  However, the above-mentioned coated metal sheet has a thermal expansion capsule or an unfoamed resin coating containing a chemical foaming agent applied to the surface of the metal plate, and then the temperature of the thermal expansion capsule exceeds the expansion start temperature or chemical foaming. It was obtained through a process of baking at a temperature at which the agent decomposes. And when a coating-film laminated metal plate is produced by such a method, a foamed resin coating film having a sufficient film thickness can be formed by a thermally expandable capsule, but the coating film becomes brittle, and a chemical foaming agent In this case, a large amount of the decomposition gas cannot be introduced into the coating film, and a foamed resin coating film having a sufficient film thickness cannot be obtained. Moreover, the said coating-film laminated metal plate had room for improvement also in the point of bending workability and coating-film adhesiveness.

JP 2009-234069 A

  This invention was made | formed in order to solve the said subject, Comprising: It raised as the subject to provide the foaming resin coating-film laminated metal plate which is excellent in damping property, bending workability, and coating-film adhesiveness.

  The foamed resin-coated laminate metal plate of the present invention that has solved the above-mentioned problems is a foamed resin-coated laminate metal plate having a foamed resin coating film having a film thickness of 150 μm or more on the surface of the metal plate, The resin coating film is formed using a resin composition containing a thermally expandable capsule and a chemical foaming agent in a mass ratio of 0.03 to 1.2 in a total amount of 3% by mass to 31% by mass. .

  In addition, in this specification, the total content rate of the said thermally expansible capsule and a chemical foaming agent means the content rate in 100 mass% of solid content in a resin composition.

  In the foamed resin-coated laminated metal plate of the present invention, the resin composition contains a resin, the thermally expandable capsule, and the chemical foaming agent, and a resin composition for forming a non-foamed layer. It is a preferred embodiment that it is divided into things.

  In the present invention, there is provided a method for producing the above foamed resin-coated laminated metal plate, wherein a foam layer-forming resin composition containing a resin, a thermally expandable capsule and a chemical foaming agent is applied to the surface of the metal plate. Forming a lower layer, drying the lower layer at a temperature at which the chemical foaming agent does not decompose, and forming an upper layer by applying a non-foamed layer forming resin composition to the surface of the lower layer after drying And a step of baking the upper layer and the lower layer at a temperature equal to or higher than the expansion start temperature of the thermally expandable capsule and the chemical foaming agent is decomposed in this order. The manufacturing method of a film | membrane laminated metal plate is also included.

  In this specification, the temperature at which the coating film is dried or baked means the highest temperature reached by the metal plate.

  In the method for producing a foamed resin-coated metal sheet of the present invention, the step of drying the lower layer is performed at a temperature lower than the expansion start temperature of the thermally expandable capsule, or the step of baking the upper layer and the lower layer is performed. It is a preferred embodiment that the heating is carried out at from 60 to 250 ° C. for 60 to 150 seconds.

  According to the present invention, it was possible to produce a foamed resin coated metal sheet having excellent vibration damping properties, bending workability, and coating film adhesion.

  The foamed resin coated metal sheet of the present invention (hereinafter sometimes referred to simply as “coated film metal sheet”) has a foamed resin film having a film thickness of 150 μm or more on the surface of the metal sheet. Using a resin composition which is a laminated metal plate and the foamed resin coating film contains a thermally expandable capsule and a chemical foaming agent in a mass ratio of 0.03 to 1.2 in a total amount of 3% to 31% by mass. It is formed. Hereinafter, the coated metal sheet of the present invention will be described in detail.

(Metal plate)
The metal plate used in the present invention is not particularly limited, and examples thereof include a steel plate or a non-ferrous metal plate, and a plated metal plate obtained by plating these with a single metal or various alloys. Specifically, for example, steel plates such as hot-rolled steel plates, cold-rolled steel plates, stainless steel plates, etc .; Examples thereof include non-ferrous metal plates such as aluminum, titanium, and zinc, or plated non-ferrous metal plates obtained by plating them. These metal plates may be subjected to, for example, phosphate treatment, chromate treatment, pickling treatment, alkali treatment, electrolytic reduction treatment, silane coupling treatment, inorganic silicate treatment, and the like as surface treatment.

(Foamed resin coating)
The coated metal sheet of the present invention has a foamed resin coating film having a thickness of 150 μm or more (preferably 170 μm or more, more preferably 300 μm or more) on at least one surface of the metal plate. If the film thickness of the foamed resin coating film is less than 150 μm, the vibration damping improvement effect due to the provision of the foamed resin coating film on the metal plate surface may not be sufficiently obtained. Since the damping property of the metal plate is improved as the thickness of the foamed resin coating film increases, the upper limit is not particularly limited, but is preferably 850 μm (more preferably 800 μm, more preferably 700 μm). This is because, when a foamed resin coating film is obtained using a resin composition containing a chemical foaming agent, the resin composition coating film is formed by taking time around the decomposition temperature of the chemical foaming agent (for example, about 150 ° C.). If baked, since the gas generated from the chemical foaming agent can be introduced into the coating in a fine and large amount while maintaining the resin viscosity in the resin composition high, a thick foamed resin coating can be obtained. . However, baking conditions for industrially used continuous coating lines are high temperature and short time (specifically, PMT (maximum temperature reached by metal plate) 200 ° C. to 250 ° C. for 60 seconds to 120 seconds from a cost standpoint. In such a baking condition, it is difficult to keep the resin viscosity high in the resin composition, and the gas generated from the chemical foaming agent cannot be introduced into the coating film in a fine and large amount. It is difficult to obtain a foamed resin coating film having a film thickness exceeding 850 μm. That is, the upper limit of the film thickness of the foamed resin coating film is naturally determined from the viewpoint of high-speed productivity.

(Resin composition)
The foamed resin coating in the coated metal sheet of the present invention has a resin composition containing a thermally expandable capsule and a chemical foaming agent in a mass ratio of 0.03 to 1.2 and a total of 3 to 31% by mass. It is formed using things.

  Thermally expandable capsules expand when a liquid (eg, hydrocarbons) contained in a thermoplastic resin shell is gasified to form a balloon, and foam a resin coating to form a thick film By improving the vibration resistance, the vibration damping property of the coated metal sheet is improved. Since the resin outer shell is often composed of a relatively hard material, if there are too many balloons, the foamed resin coating film becomes brittle, which may reduce the bending workability of the coated metal sheet. . On the other hand, a chemical foaming agent generates gas (for example, carbon dioxide, nitrogen, etc.) by thermal decomposition, and bubbles are introduced into the resin coating film. It has the effect of improving the bending workability of the film-laminated metal plate. However, if the amount of bubbles due to the chemical foaming agent increases too much, the strength of the foamed resin coating film is insufficient, and the foamed resin coating film is easily destroyed (the coating film is easily torn). There are cases where the adhesion of the coating film is lowered.

  In the present invention, by adjusting the mixing ratio of the thermally expandable capsule and the chemical foaming agent in the resin composition and the total content, it is excellent in all of vibration damping properties, bending workability, and coating film adhesion. It was possible to provide a coated metal sheet.

<Resin>
In the present invention, the resin (base resin) used as the resin composition is not particularly limited, and examples thereof include general-purpose polyester resins, acrylic resins, urethane resins, polyolefin resins, fluorine resins, and silicones. Resin can be used. Among these resins, polyester resins are preferable.

<Heat expandable capsule>
The thermally expandable capsule used in the present invention is gasified when a gasizable liquid is encapsulated in a thermoplastic resin shell and heated above the expansion start temperature of the thermally expandable capsule. There is no particular limitation as long as the liquid can be retained in the outer shell. In the present invention, it is preferable to use a thermally expandable capsule having a thermal expansion start temperature of 150 ° C. or higher (more preferably 170 ° C. or higher) and 210 ° C. or lower (more preferably 190 ° C. or lower). When the coated metal sheet of the present invention is produced by a continuous coating line, 150 ° C. is used as an organic solvent (described later) for diluting the resin composition in order to keep the viscosity change low when applying the resin composition. In many cases, an organic solvent having a boiling point of about a degree is used, and by using a thermally expandable capsule having a thermal expansion start temperature of 150 ° C. or higher, a resin composition (more specifically, a resin composition for forming a foam layer described later) ), The thermally expandable capsules can be prevented from expanding. Further, by using a thermally expandable capsule having a thermal expansion start temperature of 210 ° C. or less, a coating film of a resin composition (more specifically, a dry coating film and a non-foaming layer formation of a resin composition for forming a foam layer described later) When the laminate with the coating film of the resin composition for baking is baked, the thermally expandable capsule can be rapidly expanded.

  Specific examples of thermally expandable capsules include the “Expansel” series available from Nippon Philite, “Advancel (registered trademark)” series from Sekisui Chemical Co., Ltd., and “Matsumoto” from Matsumoto Yushi Seiyaku Co., Ltd. Examples include the “Microsphere (registered trademark)” series and the “Kureha Microsphere (registered trademark)” series manufactured by Kureha. Even when the liquid expands by gasification, these thermally expandable capsules are difficult to burst because the outer shell is excellent in deformability, and can remain in an expanded state in the foamed resin coating film. These thermally expandable capsules may be used alone or in combination of two or more.

<Chemical foaming agent>
The chemical foaming agent used in the present invention is not particularly limited as long as it generates gas upon thermal decomposition, but is preferably a chemical foaming agent having a decomposition temperature of 200 ° C. or lower. Since the thermal decomposition reaction of the chemical foaming agent proceeds slowly, when a chemical foaming agent having a decomposition temperature exceeding 200 ° C. is used, the coating film of the resin composition (more details will be described later) in the continuous coating line. When a laminate of a dry coating film for forming a foam layer resin composition and a coating film for a non-foam layer forming resin composition) is baked at a high temperature for a short time, the chemical foaming agent cannot be sufficiently foamed. There is a case. The lower the decomposition temperature of the chemical foaming agent, the better, but the lower limit is preferably 100 ° C. The decomposition temperature of a chemical foaming agent depends not only on its constituent materials but also on the particle size, and the smaller the chemical foaming agent particle size, the lower the decomposition temperature. Take it.

  As the chemical foaming agent, either an organic foaming agent or an inorganic foaming agent can be used. Examples of the organic foaming agent include azo compounds, nitroso compounds, sulfonyl hydrazide compounds, and the like. Specifically, azodicarbonamide, barium azodicarboxylate, azobisisobutyronitrile, N, N′-dinitrosopentamethylenetetramine, p-toluenesulfonyl hydrazide, p, p′-oxybis (benzenesulfonyl hydrazide), Examples include hydrazodicarbonamide, diphenylsulfone-3,3-disulfonylhydrazide, p-toluenesulfonyl semicarbazide, trihydrazinotriazine, and biurea. Of these, azo compounds such as azodicarbonamide, barium azodicarboxylate, and azobisisobutyronitrile are preferable. Examples of the inorganic foaming agent include sodium hydrogen carbonate and zinc carbonate. These chemical foaming agents may be used alone or in combination of two or more.

<Mass ratio>
In the present invention, the mass ratio of the thermally expandable capsule and the chemical foaming agent in the resin composition (thermally expandable capsule / chemical foaming agent) is 0.03 to 1.2. When the mass ratio is less than 0.03, the foamed resin coating film to be formed retains a large number of bubbles derived from the chemical foaming agent. However, the strength of the foamed resin coating film is insufficient, and the adhesiveness of the foamed resin coating film tends to be reduced (the coating film is torn off). When the mass ratio exceeds 1.2, the foamed resin coating film contains a large amount of foamed thermally expandable capsules. Since the heat-expandable capsule has a hard outer shell, the formed foamed resin coating film becomes tough but brittle, and the vibration damping property and bending workability of the coated metal sheet tend to be lowered. The mass ratio between the thermally expandable capsule and the chemical foaming agent is preferably 0.030 to 1.0, more preferably 0.11 to 0.70.

<Total content of thermally expandable capsule and chemical foaming agent>
The total content of the thermally expandable capsule and the chemical foaming agent in the resin composition is 3% by mass to 31% by mass. When the total content is less than 3% by mass, a foamed resin coating film having a sufficient film thickness cannot be obtained, and the vibration damping properties of the metal plate may not be sufficiently improved. Moreover, when the said content rate exceeds 31 mass%, the balloon of a thermal expansion and the residue of the chemical foaming agent after decomposition | disassembly (For example, sodium hydrogencarbonate was used as a chemical foaming agent in a foamed resin coating film. In this case, a large amount of sodium carbonate) will be present, and as a result, the resin content in the foamed resin coating film will be lowered, which may reduce the bending workability of the resulting coated metal sheet. is there.

<Content of chemical foaming agent>
The resin composition of the present invention preferably contains a chemical foaming agent in an amount of 2.5% by mass to 30% by mass (more preferably 5% by mass to 30% by mass, and still more preferably 7% by mass to 30% by mass). When the resin composition contains the chemical foaming agent within the above range, a coated metal sheet with excellent balance between bending workability and coating film adhesion can be obtained.

  Since the chemical foaming agent is gasified to form bubbles in the coating film, the chemical foaming agent itself does not remain in the foamed resin coating film, but a residue specific to the chemical foaming agent remains in the film. Therefore, if these residues are analyzed, the amount of chemical foaming agent used can be determined.

<Resin composition for forming foamed layer, resin composition for forming non-foamed layer>
The resin composition used in the present invention is preferably divided into a foamed layer-forming resin composition containing a resin, a thermally expandable capsule, and a chemical foaming agent, and a non-foamed layer-forming resin composition. Using these compositions, a coating film of a resin composition (more specifically, a lower layer of a foam layer-forming resin composition and an upper layer of a non-foamed layer-forming resin composition) by a method described later. The laminated metal plate is further excellent in vibration damping, coating adhesion, and bending workability by baking and integrating the coating to form a foamed resin coating. Can be made.

  When using the resin composition for foaming layer formation and the resin composition for non-foaming layer formation, it is preferable that the thermally expansible capsule and the chemical foaming agent are contained only in the resin composition for foaming layer formation. The reason will be described later.

  The types of resins (base resins) used for the resin composition for forming a foam layer and the resin composition for forming a non-foam layer may be different from each other, but the coating films ( In detail, it is preferable that it is the same kind from an adhesive viewpoint of the upper layer and lower layer) mentioned later.

<Additives>
The resin composition used in the present invention may contain a crosslinking agent in order to ensure the coating film strength. When the resin composition is composed of a foam layer-forming resin composition and a non-foamed layer-forming resin composition, even if only one of them contains a crosslinking agent, both contain a crosslinking agent. May be. Examples of the crosslinking agent include melamine resins such as “Sumimar (registered trademark)” series manufactured by Sumitomo Chemical Co., Ltd. and “Cymel (registered trademark)” series manufactured by Cytec Technology. The crosslinking agent is 5 parts by mass with respect to 100 parts by mass of the resin component in the above composition (in the case where the resin composition for forming the foamed layer and the resin composition for forming the non-foamed layer is formed). It is preferable to add to 35 parts by mass (more preferably from 10 to 25 parts by mass).

  In the above composition, in addition to the crosslinking agent, the matte agent, extender pigment, rust inhibitor, anti-settling agent, wax, metal fine particles, etc. Known additives used in the field may be added, but they may not be added. This is because these additives do not contribute to the improvement of vibration damping properties of the coated metal sheet.

(Manufacturing method of foamed resin coated metal sheet)
The coated metal sheet of the present invention may be produced by any method, but is preferably produced using the above-mentioned foamed layer forming resin composition and non-foamed layer forming resin composition. Specifically, the step of applying a foam layer forming resin composition containing a resin, a thermally expandable capsule and a chemical foaming agent to the surface of the metal plate to form a lower layer, and the chemical foaming agent do not decompose A step of drying the lower layer at a temperature, a step of applying an unfoamed layer-forming resin composition to the surface of the lower layer after drying and forming an upper layer, and an expansion start temperature of the thermally expandable capsule or higher, And the method of baking the said upper layer and the said lower layer in this order at the temperature which the said chemical foaming agent decomposes | disassembles, and the method of producing the coating-film laminated metal plate of this invention is mentioned.

  When the coated metal sheet of the present invention is produced in one coat using a resin composition (corresponding to the resin composition for forming a foamed layer of the present invention) containing a resin, a thermally expandable capsule and a chemical foaming agent. When the coating film of the composition is baked to decompose (foam) the chemical foaming agent, the generated gas escapes from the surface of the coating film into the atmosphere, and a foamed resin coating film having a sufficient film thickness is obtained. It may not be possible. On the other hand, as described above, if a coated metal sheet is produced with two coats using the lower foam layer forming resin composition and the upper non-foam layer forming resin composition, the upper layer and lower layer During baking, the upper layer prevents the gas generated in the lower layer from escaping into the atmosphere and can be retained in the coating film, thus forming a foamed resin coating film with a large film thickness and excellent vibration damping properties. It becomes easy.

  Hereinafter, the manufacturing method of the coating-film laminated metal plate of this invention is demonstrated in detail.

<Lower layer formation process>
The resin composition for forming a foam layer used in the lower layer forming step is prepared by mixing the above resin with a heat-expandable capsule, a chemical foaming agent and, if necessary, additives such as a crosslinking agent and a leveling agent, and diluting with an organic solvent or the like. It is preferable to adjust to a viscosity suitable for coating. The mass ratio between the thermally expandable capsule and the chemical foaming agent contained in the foam layer-forming resin composition, and the total content are as described above for the entire resin composition including the non-foam layer-forming resin composition described below. There is no particular limitation as long as it is within the range.

  The organic solvent used for dilution is not particularly limited, and is preferably an organic solvent having a low boiling point from the viewpoint of facilitating the subsequent drying step. In addition, when manufacturing the coating-layer laminated metal plate of this invention by a continuous coating line, it is using the organic solvent whose boiling point is 120 to 180 degreeC from a viewpoint of suppressing the viscosity change of resin in a subsequent baking process. preferable.

  Examples of the organic solvent include aromatic hydrocarbons such as toluene and xylene; aliphatic esters such as ethyl acetate and butyl acetate; alicyclic hydrocarbons such as cyclohexane; and aliphatic hydrocarbons such as hexane and pentane. And the like; ketones such as methyl ethyl ketone and cyclohexanone. In addition, it is possible to use a solvent having a strong polarity (such as ketones or dimethylformamide). However, since the thermally expandable capsule may swell over time due to these polar solvents, the resin composition may be used immediately before use. Care should be taken such as mixing. Said organic solvent may be used independently or may be used in combination of 2 or more type.

  The method for applying the resin composition for forming a foam layer to a metal plate is not particularly limited, and for example, a bar coater method, a roll coater method, a spray method, a curtain flow coater method, or the like can be employed.

  The coating amount of the foam layer-forming resin composition is not particularly limited as long as the film thickness of the finally obtained foamed resin coating film can be 150 μm or more.

<Drying process>
Drying after applying the resin composition for forming the foam layer to the metal plate is performed by heating the metal plate after the lower layer is formed at a temperature at which the chemical foaming agent is not decomposed. In addition, the drying process in the case of producing the coated metal sheet of the present invention on a continuous coating line is performed in a short time (specifically, about 60 seconds to 120 seconds) from the viewpoint of cost. Under such short drying conditions, a chemical foaming agent having a relatively large particle size is not decomposed even when heated to a temperature higher than the decomposition temperature of the chemical foaming agent (or the upper limit temperature if there is a range of decomposition temperatures). For this reason, if it is the said drying time, the upper limit of drying temperature is 60 degreeC (preferably 50 degreeC, More preferably, it is higher than the decomposition temperature of the chemical foaming agent to be used (the upper limit temperature when the decomposition temperature has a width). (40 ° C) may be set higher.

  The above drying temperature is not only a temperature at which decomposition of the chemical foaming agent is suppressed, but is also a preferred embodiment that is lower than the expansion start temperature of the thermally expandable capsule. When the thermally expandable capsule of the foam layer forming resin composition expands, irregularities are formed on the surface of the lower layer, and the surface smoothness cannot be maintained. Therefore, it is necessary to apply the resin composition for forming the non-foamed layer for the upper layer. There are cases where it cannot be performed uniformly.

  In addition, the value described in the catalog can be employ | adopted for the decomposition temperature of a chemical foaming agent, and the expansion | swelling start temperature of a thermally expansible capsule, and can also be measured also by thermal analysis.

  Specifically, a method of drying for about 60 seconds to 120 seconds at a maximum reached temperature of about 130 to 160 ° C. of the metal plate can be mentioned.

<Upper layer forming process>
After the lower layer is dried, the non-foamed layer forming resin composition is applied on the lower layer. The composition used in this step is preferably adjusted to a viscosity suitable for coating by mixing the resin and additives such as a crosslinking agent and a leveling agent as necessary, and diluting with an organic solvent. Examples of the organic solvent used in this step and the coating method of the composition include those described above.

  The resin composition for forming a non-foamed layer is used for preventing a gas generated in the lower layer from escaping into the atmosphere in a subsequent baking step. For this reason, in 100% by mass of the solid content in the composition, the resin content is 60% by mass or more (more preferably 70% by mass or more, more preferably 80% by mass or more, particularly preferably 90% by mass or more). It is preferable.

  The resin composition for forming a non-foamed layer may not include a thermally expandable capsule or a chemical foaming agent, but may include a thermally expandable capsule or the like as long as the object of the present invention is not impaired. Specifically, in the solid content of 100% by mass of the resin composition for forming a non-foamed layer, the total of the thermally expandable capsule and the chemical foaming agent is 5% by mass or less (preferably 2% by mass or less, more preferably 1% by mass). % Or less).

  The adhesion amount of the resin composition for forming a non-foamed layer is particularly limited as long as the effect of using the composition can be exhibited and the film thickness of the foamed resin coating film finally obtained is 150 μm or more. However, it is preferably applied to the lower layer so that the dry film thickness is 10 μm or more (more preferably 15 μm or more). If the film thickness of the upper layer is too thin, the gas generated in the lower layer may escape from the surface of the upper layer, and it may not be possible to ensure excellent vibration damping properties. The upper limit of the film thickness of the upper layer is not particularly limited. In the present invention, if the foam layer-forming resin composition and the non-foamed layer-forming resin composition are applied so that the upper layer and the lower layer have the same film thickness, the upper layer can be formed using common coating conditions. And the lower layer can be formed.

<Baking process>
In this step, the thermal expandable capsule and the chemical foaming agent are foamed by baking the upper and lower coating layers at a temperature equal to or higher than the expansion start temperature of the thermally expandable capsule and the chemical foaming agent is decomposed, and a crosslinking agent. If there is, cure the resin. Since the rate of progress of the thermal decomposition reaction of the chemical foaming agent is moderate, baking at a temperature as high as possible within the range where yellowing of the resin does not occur is preferable because the baking time can be shortened.

  Specifically, the metal plate is baked for about 60 seconds to 150 seconds (more preferably 80 seconds to 130 seconds) at a maximum temperature of 180 ° C. to 250 ° C. (more preferably 200 ° C. to 230 ° C.). From the viewpoint of high speed productivity.

(Characteristic)
As a measure of vibration damping properties of the coated metal sheet of the present invention, the loss factor is preferably 0.0035 or more. In addition, the loss coefficient of the electrogalvanized steel sheet measured in the Example mentioned later was 0.0020.

  In addition, the present invention can be implemented in a mode in which various improvements, modifications, and variations are added based on the knowledge of those skilled in the art without departing from the spirit of the present invention.

  Hereinafter, the present invention will be described in detail based on examples. However, the following examples are not intended to limit the present invention, and all modifications made without departing from the spirit of the preceding and following descriptions are included in the technical scope of the present invention. Unless otherwise specified, “part” means “part by mass” and “%” means “% by mass”.

  First, the evaluation method used in the production example will be described below.

[Thickness evaluation 1]
In the production example, after applying the resin composition for forming a non-foamed layer, the metal plate was heated and dried at a maximum temperature (PMT) of 200 ° C. to 220 ° C. for 100 seconds to 130 seconds, and an unfoamed resin coating film ( A metal plate having an upper layer and a lower layer was produced. Next, a 15 mm × 25 mm sample was cut out from this metal plate, and the film thickness of the resin coating film before foaming was determined from cross-sectional observation by SEM.

[Thickness evaluation 2]
A 15 mm × 25 mm sample was cut out from the foamed resin coating film laminated metal plate produced in the production example, and the film thickness of the foamed resin coating film was determined from cross-sectional observation by SEM.

[Evaluation of coating film adhesion]
A 50 mm x 50 mm sample was cut out from the foamed resin-coated laminated metal plate produced in the production example, and a tape peeling test (tape used: “Cello Tape (registered trademark) No. 405” manufactured by Nichiban) was performed on this sample Calculate the area of the foamed resin film attached to the tape and divide by the entire area of the tape attached to the foamed resin film to calculate the occupancy of the film on the tape surface. The difficulty of film breakage was evaluated according to the following three evaluation criteria.
(Evaluation criteria)
◎: Occupancy rate 15% or less ○: Occupancy rate 15% to 49% or less ×: Occupancy rate 49% or less

[Bending workability evaluation]
A 50 mm × 50 mm sample was cut out from the foamed resin-coated laminated metal plate produced in the production example, subjected to a 5T bending test, and then allowed to stand at room temperature (25 ° C.) for 1 week. Was measured, and bending workability was evaluated according to the following three evaluation criteria.
(Evaluation criteria)
◎: No crack ○: There is a crack of 10 mm or less ×: There is a crack of more than 10 mm

[Vibration evaluation]
The foamed resin-coated laminated metal plate produced in the production example was cut into a width of 30 mm and a length of 150 mm, the length from the end to the length direction was 5 mm, and the width direction was 15 mm. The yarn was glued in the direction. About the obtained test piece, the damping ratio was measured using the hanging impact excitation method (FIG. 5) described in JIS G 0602 (1993). Specifically, the test piece is suspended with the length from the support column to one end being 500 mm, a sensor is attached to the metal plate side 80 mm below the starting point, and 20 mm below the sensor center (length from one end is 105 mm) Then, the surface of the resin coating at 15 mm in the width direction is hit vertically with 5 to 15 N using an impulse hammer. The ambient temperature was room temperature. As shown in FIG. 5 of JIS G 0602 (1993), the excitation force F is sent from the hammer through the amplifier to the analysis device, and the response acceleration A is also sent from the sensor to the analysis device. The analysis conditions this time were an analysis frequency (upper limit frequency) of 10 kHz, a sampling frequency (data acquisition speed) of 25.6 kHz, and a cutoff frequency of the bandpass filter was 850 Hz for the high pass and 910 Hz for the low pass. The obtained damping ratio was doubled to determine the loss factor, and the damping performance was evaluated.

1. Paint of resin composition for forming foam layer The following resin (base resin) and a crosslinking agent are mixed at a solid content mass ratio of 100: 20 to obtain a mixture. Here, the following thermally expandable capsule and chemical foaming agent are obtained. And a mass ratio (thermally expandable capsule / chemical foaming agent) in the range of 0 to 2 and the total content in the solid content of 100% by mass of the resin composition for forming a foamed layer is 0 to 70% by mass. After that, the solid content concentration is adjusted to 50 to 60% using the following organic solvent, and then stirred with a disper stirrer at 3000 rpm × 5 minutes to form a foam layer-forming resin composition paint Was prepared.

Resin (base resin): Organic solvent-soluble polyester resin “Byron (registered trademark) 600 (Tg 47 ° C.)” manufactured by Toyobo Co., Ltd.
・ Crosslinking agent: Melamine resin (“Sumimar (registered trademark) M-40ST” manufactured by Sumitomo Chemical Co., Ltd., solid content: 80%)
・ Organic solvent: xylene 50% + cyclohexanone 50% mixed solvent (Daishin Chemical)
-Chemical foaming agent: Cellmic (registered trademark) 266 (manufactured by Sankyo Kasei Co., Ltd., decomposition temperature 140 ° C to 170 ° C)
Thermally expandable capsule: EXPANSEL 980-120 (manufactured by Nippon Philite, foaming start temperature 158 ° C., maximum foaming temperature 215 ° C. to 235 ° C.)

2. Paint of non-foamed layer forming resin composition The above resin (base resin) and a crosslinking agent are mixed at a solid content mass ratio of 100: 20, and the solid content concentration is adjusted to 50 to 60% using the above organic solvent. It adjusted so that it might become, and it stirred at 3000 rpm x 5 minutes with the disper stirrer, and prepared the coating material of the resin composition for non-foaming layer formation.

(Production Examples 1-41)
The prepared paint for forming a foam layer was applied to an A4 size electrogalvanized steel sheet having a plate thickness of 0.8 mm with a bar coater, and heated and dried at PMT 150 ° C. for 80 seconds to form a lower layer. Next, the prepared coating composition for forming a non-foamed layer is applied onto the lower layer with a bar coater and heated at PMT 210 ° C. for 120 seconds (Production Example 41 is heated at PMT 230 ° C. for 120 seconds). Were integrated by baking, and foamed resin-coated laminated metal plates 1 to 41 were produced.

  About the obtained coating-film laminated metal plates 1-41, the film thickness, coating-film adhesiveness, bending workability, and damping property were evaluated by said method. The results are shown in Table 1.

Claims (4)

On the surface of the metal plate, a foamed resin coating layer metal plate having a foamed resin coating layer and a non-foamed layer made of a non-foaming layer forming resin composition,
The total film thickness of the foamed resin coating layer and the non-foamed layer is 150 μm or more and 850 μm or less,
The foamed resin coating layer contains a thermally expandable capsule and a chemical foaming agent in a mass ratio of 0.03 to 0.70 in a total of 15 mass% to 31 mass% , and the content of the chemical foaming agent is It is formed using the resin composition for foaming resin coating-film layer formation which is 15 mass% or more . The foaming resin-coating laminated metal plate characterized by the above-mentioned. A method for producing a foamed resin coated metal sheet according to claim 1 ,
Applying a foam layer forming resin composition containing a resin, a thermally expandable capsule and a chemical foaming agent to the surface of the metal plate to form a lower layer;
Drying the lower layer at a temperature at which the chemical blowing agent does not decompose;
Applying a non-foamed layer forming resin composition to the surface of the lower layer after drying to form an upper layer;
A foamed resin-coated laminated metal sheet comprising the steps of baking the upper layer and the lower layer in this order at a temperature equal to or higher than the expansion start temperature of the thermally expandable capsule and the chemical foaming agent is decomposed. Manufacturing method. The manufacturing method of the foaming resin coating-film laminated metal plate of Claim 2 which performs the process of drying the said lower layer below the expansion start temperature of the said thermally expansible capsule. The manufacturing method of the foaming resin coating-film laminated metal plate of Claim 2 or 3 which performs the process of baking the said upper layer and the said lower layer by heating at 180 to 250 degreeC for 60 second-150 second.