JP4851904B2 - Fluorine resin coated steel sheet - Google Patents

Description

  The present invention relates to a fluororesin-coated steel sheet used for building materials such as roofs, walls and signboards.

Fluororesin-coated steel sheets are excellent in weather resistance, heat resistance, and the like, and thus have been used in various fields, and many have been provided so far. For example, the fluororesin coating described in Patent Document 1 is formed by coating a film mainly composed of fluororesin on a base material such as aluminum, and is non-adhesive, wear resistant, and corrosion resistant. Improvements are being made.
JP-A-6-133855

  However, in conventional fluororesin-coated steel sheets, if a large pressure is applied to the front and back of the steel sheet by being wound in a coil shape, pressure marks (pressure marks) are generated on the surface that is a decorative surface, and the appearance is impaired. It was a thing that would be lost. Moreover, once a pressure mark is generated in this way, the coil does not disappear over time even if the coil is unwound and left unattended.

  This invention is made | formed in view of said point, and it aims at providing the fluororesin coating steel plate which can prevent generation | occurrence | production of a pressure mark.

In the fluororesin-coated steel sheet according to claim 1 of the present invention, the fluorine clear layer 6 in which the mass ratio of the fluororesin and the acrylic resin is 75:25 to 90:10, the inorganic fired pigment is 10 to 35% by mass , the organic pigment A polyester resin coating having a glass transition temperature of 10 to 20 ° C. and a glass transition temperature of 10 to 30% by mass and a fluorine colored layer 5 formed of a fluorine resin coating containing an acrylic resin. The film 3 is formed on the back surface of the steel plate 1.

  According to the fluororesin-coated steel sheet according to claim 1 of the present invention, the ratio of the fluororesin is 75 parts by mass or more with respect to 100 parts by mass of the total fluoropolymer and acrylic resin in the fluororesin coating film. Crystallization of the coating is promoted, plastic deformation due to compression can be suppressed, and when the glass transition temperature of the polyester resin coating is 20 ° C. or less, the polyester resin coating is softened and cushioned. As a result, even if the fluororesin coating film and the polyester resin coating film are pressed against each other by coiling or the like, pressure marks can be prevented from being generated on the surface of the fluororesin coating film. .

  Embodiments of the present invention will be described below.

As shown in FIG. 1, the fluororesin-coated steel sheet according to the present invention is formed by laminating a primer layer 4, a fluorine colored layer 5, and a fluorine clear layer 6 in this order on the surface of the steel sheet 1, and at the back of the steel sheet 1 The polyester resin coating film 3 can be formed by laminating in this order . However, the weight ratio of fluorocarbon resin and an acrylic resin in the fluororesin coating film 2 located on the outermost surface (full Tsu containing clear layer 6) is 75: 25 to 90: 10. Moreover, the glass transition temperature (Tg) of the polyester resin coating film 3 is 10-20 degreeC.

  Although it does not specifically limit as the steel plate 1 in this invention, For example, plated steel plates, such as a hot-dip aluminum-zinc alloy plating steel plate and a hot dip galvanization steel plate, a stainless steel plate etc. can be used.

  Prior to the formation of the primer layer 4, a chemical conversion treatment layer (not shown in FIG. 1) can be formed on both surfaces of the steel plate 1. Examples of the chemical conversion treatment layer include a chromate (chromate) treatment layer, a phosphate treatment layer, and a composite oxide film.

  The chromate (chromate) treatment layer is formed from a hydrated oxide containing trivalent chromium and hexavalent chromium by treating the surface of the steel sheet 1 with an aqueous solution containing hexavalent chromium and an inorganic acid such as sulfuric acid. Can be formed as a layer. Moreover, a phosphate process layer is a layer which consists of a 3rd phosphate formed by processing the surface of the steel plate 1 using the aqueous solution containing a 1st phosphate and phosphoric acid. Examples of the type of phosphate include zinc phosphate, manganese phosphate, and iron phosphate. In addition, the thickness of the chemical conversion treatment layer is generally 1 to 2 μm in the case of the phosphate treatment layer.

  The primer layer 4 is a surface of the steel plate 1 as a primer for the purpose of improving the adhesion of the coating film or imparting rust prevention properties (in the case of forming a chemical conversion treatment layer, a chemical conversion treatment is performed). Layer surface). As the undercoat paint (primer) for forming the primer layer 4, for example, an epoxy resin-based paint, a polyurethane resin-based paint, or the like can be used. A rust preventive pigment or the like can be contained. And after applying the undercoat paint to the surface of the steel plate 1 using a spray, bar coater, roller curtain coater, curtain flow coater, roll coater, etc., it is dried by heating it through a hot air drying furnace or a dielectric heating device. The primer layer 4 can be formed by curing. The primer layer 4 can be formed so as to be in close contact with the chemical conversion treatment layer when the chemical conversion treatment layer is formed in advance, and may be in direct contact with the steel plate 1 when the chemical conversion treatment layer is not formed. Can be formed. At this time, two or more kinds of primer layers 4 having different compositions may be sequentially laminated to form a multilayer primer layer 4 having two or more layers. The coating amount of the undercoat paint and the film thickness of the primer layer 4 can be adjusted as appropriate, but the film thickness of the primer layer 4 is preferably 1 to 10 μm.

As the intermediate coating material for forming the fluorine coloring layer 5, a fluorine resin coating material containing an inorganic fired pigment, an organic pigment, and an acrylic resin can be used. Examples of the fluororesin used in this fluororesin coating material include polyvinylidene fluoride, polytrifluoroethylene chloride, polytetrafluoroethylene, etc. Examples of the solvent include xylene / isobutyl alcohol, n- Examples thereof include butyl alcohol, propylene glycol monomethyl ether, cyclohexane, DBE (dibasic acid ester), and Solevesso .

  Examples of the inorganic calcined pigment include, for example, white pigments such as titanium oxide, zinc white, and lead white, yellow pigments such as iron oxide yellow, yellow lead, and cadmium yellow, orange pigments such as molybdate orange, bengara, cadmium red, Red pigments such as red lead, red and iron oxide red, green pigments such as chromium oxide and chrome green, blue pigments such as bitumen, ultramarine and cobalt blue, purple pigments such as manganese violet, iron black, graphite, carbon black, etc. In addition to black pigments, calcium carbonate, barium sulfate, silica, alumina white, gloss white, and the like can be used. The content of such an inorganic fired pigment in the fluorine-colored layer 5 is preferably 10 to 35% by mass.

  Examples of organic pigments that can be used include fast yellow, disazo yellow, pyrazolone orange, lake red C, brilliant carmine 6B, quinacridone red, phthalocyanine blue, and phthalocyanine green. The content of such an organic pigment in the fluorine colored layer 5 is preferably 10 to 30% by mass.

  Then, after applying the intermediate coating to the surface of the primer layer 4 using a spray, bar coater, roller curtain coater, curtain flow coater, roll coater, etc., it is heated through a hot air drying furnace or a dielectric heating device. The fluorine-colored layer 5 can be formed by drying and curing. The coating amount of the intermediate coating and the film thickness of the fluorine colored layer 5 can be adjusted as appropriate, but the film thickness of the fluorine colored layer 5 is preferably 10 to 20 μm.

As the top coat for forming the fluorine clear layer 6, a fluororesin paint containing a fluororesin and an acrylic resin is used. Examples of the fluororesin used in this fluororesin coating material include polyvinylidene fluoride, polytrifluoroethylene chloride, polytetrafluoroethylene, etc. Examples of the solvent include xylene / isobutyl alcohol, n- Examples thereof include butyl alcohol, propylene glycol monomethyl ether, cyclohexane, DBE (dibasic acid ester), and Solevesso. Here, the weight ratio of fluorocarbon resin and acrylic resin definitive fluorine clear layer 6 is 75: 25 to 90: such that 10, in which previously adjusted the amount of the fluororesin in the top coat. In addition, the pigment is not contained in the top coat.

  Then, after applying the top coat to the surface of the fluorine colored layer 5 using a spray, bar coater, roller curtain coater, curtain flow coater, roll coater, etc., it is heated by passing it through a hot air drying furnace or a dielectric heating device. The fluorine clear layer 6 can be formed by drying and curing.

  In this way, the fluororesin coating film 2 having a mass ratio of fluororesin and acrylic resin of 75:25 to 90:10 can be formed on the surface of the steel plate 1, but the total amount of fluororesin and acrylic resin is 100 mass. If the ratio of the fluororesin to the part is less than 75 parts by mass, crystallization of the fluororesin coating film 2 cannot be promoted, and plastic deformation due to compression cannot be suppressed. When the ratio of the fluororesin exceeds 90 parts by mass with respect to 100 parts by mass of the total amount of the fluororesin and the acrylic resin, the adhesion with the fluorine colored layer 5 or the primer layer 4 is lowered.

  Here, the top coating may be applied after the intermediate coating for forming the fluorine-colored layer 5 is dried and cured, but after the top coating is applied to the surface of the intermediate coating before drying and curing, the intermediate coating is applied. You may use what is called wet on wet (two coat one baking) which finishes by baking and drying a coating material and a top-coat coating material simultaneously. When this construction method is used, the adhesion between the fluorine colored layer 5 and the fluorine clear layer 6 can be further improved. The film thickness of the fluorine clear layer 6 is preferably 5 to 10 μm. Thus, when the film thickness of the fluorine clear layer 6 is 5 μm or more, weather resistance and gloss can be further enhanced. However, when the fluorine clear layer 6 becomes excessively thick, wrinkles may occur, so the upper limit of the film thickness of the fluorine clear layer 6 is 10 μm as described above.

  On the other hand, a polyester resin coating film 3 is formed on the back surface of the steel plate 1 through a primer layer 4. Formation of the primer layer 4 on the back surface of the steel plate 1 can be performed in the same manner as the formation of the primer layer 4 on the surface of the steel plate 1. Examples of the polyester resin paint for forming the polyester resin coating film 3 include a dibasic acid (linear monomer) such as terephthalic acid and a dihydric alcohol (linear monomer) such as 1,6-hexanediol. For example, xylene / isobutyl alcohol, n-butyl alcohol, propylene glycol monomethyl ether, cyclohexane, DBE (dibasic acid ester) can be used. Solevesso, ketones, aromatic hydrocarbons and the like can be used. The polyester resin paint contains a melamine resin as a cross-linking agent, an inorganic calcined pigment or organic pigment as described above, a silica powder as a matting agent, a silica powder as a matting agent, a surface conditioner or a curing catalyst, and the like. May be. Here, if the molecular weight of the polyester resin contained in the polyester resin coating is adjusted to 6000 to 10,000 in advance, the glass transition temperature of the polyester resin coating film 3 can be easily set to 10 to 20 ° C. And after applying the polyester resin paint to the back surface of the steel plate 1 using a spray, bar coater, roller curtain coater, curtain flow coater, roll coater, etc., this is heated through a hot air drying furnace or a dielectric heating device. The polyester resin coating film 3 can be formed by drying and curing. The coating amount of the polyester resin paint and the film thickness of the polyester resin coating film 3 can be adjusted as appropriate, but the film thickness of the polyester resin coating film 3 is preferably 5 to 15 μm.

  Thus, although the polyester resin coating film 3 whose glass transition temperature is 10-20 degreeC can be formed in the back surface of the steel plate 1, it is tackiness (adhesiveness) that a glass transition temperature is less than 10 degreeC. Will become bigger. Then, for example, when the fluororesin-coated steel sheet is wound into a coil shape, it becomes very difficult to unwind the coil later, and a plurality of fluororesin-coated steel sheets cut to a predetermined size are stacked. In some cases, it becomes very difficult to remove them one after another. On the other hand, when the glass transition temperature exceeds 20 ° C., the polyester resin coating film 3 cannot be softened and the cushioning property cannot be improved.

  As described above, a fluororesin-coated steel sheet as shown in FIG. 1 can be manufactured. In the fluororesin-coated steel sheet produced in this way, the following advantageous effects can be obtained as compared with the conventional steel sheet. That is, when the ratio of the fluororesin is 75 parts by mass or more with respect to 100 parts by mass of the total of the fluororesin and the acrylic resin in the fluororesin coating film 2 formed on the surface of the fluororesin coated steel sheet, The crystallization of No. 2 is promoted, and plastic deformation due to compression can be suppressed. Moreover, when the glass transition temperature of the polyester resin coating film 3 formed on the back surface of the fluororesin-coated steel sheet is 20 ° C. or less, the polyester resin coating film 3 is softened and the cushioning property can be improved. . As a result, even if the fluororesin coating film 2 and the polyester resin coating film 3 are pressed against each other by coiling or the like, it is possible to prevent pressure marks from being generated on the surface of the fluororesin coating film 2.

  Hereinafter, the present invention will be specifically described by way of examples.

Example 1
As the steel plate 1, a molten 55% aluminum-zinc alloy plated steel plate having a thickness of 0.40 mm was used. A chemical conversion treatment layer was formed on both surfaces of the steel plate 1 using a coating chromate solution (“ZM-1300AN” manufactured by Nihon Parkerizing Co., Ltd.). And after apply | coating undercoat (primer) to the surface of this chemical conversion treatment layer, this is heated for 45 second to the final reached temperature of 190 degreeC, and is hardened by drying, The primer layer 4 with a film thickness of 5 micrometers is formed on both surfaces of the steel plate 1 Formed.

  Here, as the undercoat paint, an epoxy resin primer (“Fine Tough D Primer GL64P” manufactured by Nippon Fine Coatings Co., Ltd.) was used.

  Next, after applying an intermediate coating on the surface of one primer layer 4, this was heated to a final temperature of 250 ° C. for 45 seconds to be dried and cured, thereby forming a fluorine colored layer 5 having a thickness of 20 μm. .

  Here, as the intermediate coating material, a fluorine resin coating material (“Dick Flow EF” manufactured by Nippon Fine Coatings Co., Ltd.) blended with an organic pigment and an inorganic fired pigment as shown in [Table 1] below was used. .

  Next, after applying a top coating to the surface of the fluorine colored layer 5, this was heated and dried at a final temperature of 250 ° C. for 45 seconds to form a fluorine clear layer 6 having a thickness of 5 μm.

  Here, a fluororesin paint (“Dick Flow EF Clear” manufactured by Nippon Fine Coatings Co., Ltd.) was used as the top coat. The mass ratio of the fluororesin and the acrylic resin in the fluororesin coating film 2 (fluorine clear layer 6) located on the outermost surface is 75:25.

  On the other hand, after applying a polyester resin coating to the primer layer 4 on the back surface of the steel plate 1, the polyester resin coating film 3 having a film thickness of 5 μm is formed by heating and drying the polyester resin coating for 45 seconds to a final temperature of 250 ° C. Thus, a fluororesin-coated steel sheet as shown in FIG. 1 was produced.

  Here, “NSC833-20” manufactured by Nippon Fine Coatings Co., Ltd. was used as the polyester resin paint. The glass transition temperature of the polyester resin coating film 3 is 20 ° C.

(Example 2)
A fluororesin-coated steel sheet was produced in the same manner as in Example 1 except that the mass ratio of the fluororesin and the acrylic resin in the fluoroclear layer 6 was 80:20.

(Example 3)
A fluororesin-coated steel sheet is produced in the same manner as in Example 1 except that the mass ratio of the fluororesin and the acrylic resin in the fluoroclear layer 6 is 80:20 and the glass transition temperature of the polyester resin coating 3 is 10 ° C. did.

  In addition, as a polyester resin coating material for forming the polyester resin coating film 3, “NSC833-10” manufactured by Nippon Fine Coatings Co., Ltd. was used.

Example 4
A fluororesin-coated steel sheet is produced in the same manner as in Example 1 except that the mass ratio of the fluororesin and the acrylic resin in the fluoroclear layer 6 is 90:10 and the glass transition temperature of the polyester resin coating 3 is 15 ° C. did.

  In addition, as a polyester resin paint for forming the polyester resin coating film 3, “NSC833-15” manufactured by Nippon Fine Coatings Co., Ltd. was used.

( Reference Example 5)
As the steel plate 1, a molten 55% aluminum-zinc alloy plated steel plate having a thickness of 0.40 mm was used. A chemical conversion treatment layer was formed on both surfaces of the steel plate 1 using a coating chromate solution (“ZM-1300AN” manufactured by Nihon Parkerizing Co., Ltd.). And after apply | coating undercoat (primer) to the surface of this chemical conversion treatment layer, this is heated for 45 second to the final reached temperature of 190 degreeC, and is hardened by drying, The primer layer 4 with a film thickness of 5 micrometers is formed on both surfaces of the steel plate 1 Formed.

  Here, as the undercoat paint, an epoxy resin primer (“Fine Tough D Primer GL64P” manufactured by Nippon Fine Coatings Co., Ltd.) was used.

  Next, after applying an intermediate coating on the surface of one primer layer 4, this was heated to a final temperature of 250 ° C. for 45 seconds to be dried and cured, thereby forming a fluorine colored layer 5 having a thickness of 20 μm. .

  Here, as the intermediate coating material, a fluororesin coating material (“Dick Flow EF” manufactured by Nippon Fine Coatings Co., Ltd.) blended with an organic pigment and an inorganic fired pigment as shown in [Table 1] was used. . The mass ratio of the fluororesin and the acrylic resin in the fluororesin coating film 2 (fluorine colored layer 5) located on the outermost surface is 75:25.

  On the other hand, after applying a polyester resin coating to the primer layer 4 on the back surface of the steel plate 1, the polyester resin coating film 3 having a film thickness of 5 μm is formed by heating and drying the polyester resin coating for 45 seconds to a final temperature of 250 ° C. Thus, a fluororesin-coated steel sheet as shown in FIG. 2 was produced.

  Here, “NSC833-20” manufactured by Nippon Fine Coatings Co., Ltd. was used as the polyester resin paint. The glass transition temperature of the polyester resin coating film 3 is 20 ° C.

( Reference Example 6)
A fluororesin-coated steel sheet was produced in the same manner as in Reference Example 5 except that the mass ratio of the fluororesin and the acrylic resin in the fluorocolored layer 5 was 80:20.

( Reference Example 7)
A fluororesin-coated steel sheet is produced in the same manner as in Reference Example 5 except that the mass ratio of the fluororesin and the acrylic resin in the fluorocolored layer 5 is 80:20 and the glass transition temperature of the polyester resin coating 3 is 10 ° C. did.

  In addition, as a polyester resin coating material for forming the polyester resin coating film 3, “NSC833-10” manufactured by Nippon Fine Coatings Co., Ltd. was used.

( Reference Example 8)
A fluororesin-coated steel sheet is produced in the same manner as in Reference Example 5 except that the mass ratio of the fluororesin and the acrylic resin in the fluorocolored layer 5 is 90:10 and the glass transition temperature of the polyester resin coating 3 is 15 ° C. did.

  In addition, as a polyester resin paint for forming the polyester resin coating film 3, “NSC833-15” manufactured by Nippon Fine Coatings Co., Ltd. was used.

(Comparative Example 1)
A fluororesin-coated steel sheet is produced in the same manner as in Example 1 except that the mass ratio of the fluororesin and acrylic resin in the fluoroclear layer 6 is 70:30 and the glass transition temperature of the polyester resin coating 3 is 10 ° C. did.

  In addition, as a polyester resin coating material for forming the polyester resin coating film 3, “NSC833-10” manufactured by Nippon Fine Coatings Co., Ltd. was used.

(Comparative Example 2)
A fluororesin-coated steel sheet is produced in the same manner as in Example 1 except that the mass ratio of the fluororesin and the acrylic resin in the fluoroclear layer 6 is 70:30 and the glass transition temperature of the polyester resin coating 3 is 35 ° C. did.

  In addition, as a polyester resin paint for forming the polyester resin coating film 3, “For Dick Flow Rimen (green color)” manufactured by Nippon Fine Coatings Co., Ltd. was used.

(Comparative Example 3)
A fluororesin-coated steel sheet is manufactured in the same manner as in Example 1 except that the mass ratio of the fluororesin and the acrylic resin in the fluoroclear layer 6 is 80:20 and the glass transition temperature of the polyester resin coating 3 is 35 ° C. did.

  In addition, as a polyester resin paint for forming the polyester resin coating film 3, “For Dick Flow Rimen (green color)” manufactured by Nippon Fine Coatings Co., Ltd. was used.

(Comparative Example 4)
A fluororesin-coated steel sheet is produced in the same manner as in Example 1 except that the mass ratio of the fluororesin and the acrylic resin in the fluoroclear layer 6 is 95: 5 and the glass transition temperature of the polyester resin coating 3 is 10 ° C. did.

  In addition, as a polyester resin coating material for forming the polyester resin coating film 3, “NSC833-10” manufactured by Nippon Fine Coatings Co., Ltd. was used.

(Pressure mark accelerated lab test)
Each fluororesin coated steel sheet was subjected to a pressure mark accelerated laboratory test. This test was performed as follows. That is, after stacking two sheets of fluororesin-coated steel sheets cut to a size of 5 cm × 5 cm, a load of 4.9 MPa (50 kg / cm ² ) was applied to the stacked samples with a press machine for 24 hours. Then, the samples were peeled off one by one, and the appearance of the fluororesin coating film 2 (fluorine clear layer 6) of each sample was visually observed and evaluated according to the following criteria. The results are shown in [Table 2] below.

  “O”: No pressure mark was generated.

  “△”: Some pressure marks were generated.

  “×”: A pressure mark is generated.

(hardness)
About each fluororesin coated steel plate, the pencil hardness test based on 13.2.3 of JIS G 3322 was done, and hardness was evaluated. The results are shown in [Table 2] below.

(Processability)
About each fluororesin coating steel plate, the bending test based on 13.2.2 of JISG3322 was done, and the workability was evaluated by observing the presence or absence of the crack in a bending part with a 10 times loupe. The results are shown in [Table 2] below. In addition, “2T” in the following [Table 2] means that cracks do not occur in the case of two plates whose inner thickness of bending is the display thickness (T: 0.40 mm).

(SST)
Each fluorine resin coated steel sheet was subjected to a salt spray test (SST) based on JIS Z 2371. The results are shown in [Table 2] below.

  As seen in [Table 2] above, it was confirmed that no pressure marks were generated in the fluororesin-coated steel sheets of any of the examples.

It is sectional drawing which shows an example of embodiment of this invention. It is sectional drawing which shows an example of embodiment of a reference example .

Explanation of symbols

1 Steel plate 2 Fluorine resin coating 3 Polyester resin coating

Claims (1)

Fluorine resin paint in which the fluorine clear layer in which the mass ratio of the fluororesin and the acrylic resin is 75:25 to 90:10 contains 10 to 35% by mass of the inorganic fired pigment, 10 to 30% by mass of the organic pigment, and the acrylic resin And a polyester resin coating film having a glass transition temperature of 10 to 20 ° C. is formed on the back surface of the steel sheet through a fluorine colored layer formed in Painted steel sheet.

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