Matte coating film

Abstract

To provide a roofing matte coating film that exhibits a matting effect at oblique incidence and that enables a uniform matte appearance to be obtained irrespective of observation angle and film thickness.SOLUTION: A matte coating film for roofing is provided, wherein a difference (Δ60G) between a 60-degree specular gloss of a dry coating film having a film thickness of 30 μm or more and 40 μm or less and a 60-degree specular gloss of a dry coating film having a film thickness of 60 μm or more and 80 μm or less is less than 5, a 85-degree specular gloss of the dry coating film having a film thickness of 30 μm or more and 40 μm or less is 20 or more and 40 or less, and a difference (Δ85G) between the 85-degree specular gloss of the dry coating film having a film thickness of 30 μm or more and 40 μm or less and the 85-degree specular gloss of the dry coating film having a film thickness of 60 μm or more and 80 μm or less is less than 15.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a matte coating for roofs. [Background technology]

[0002] BACKGROUND ART Matte coating compositions for giving a matte appearance to the exterior of buildings have been known (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2021-138799 Summary of the Invention [Problem to be solved by the invention]

[0004] The technology disclosed in Patent Document 1 is a technology for imparting a matte appearance to a topcoat layer applied to decorative materials used on building walls, etc. Recently, there has been a demand for coatings with a matte effect that reduces gloss and glare, even for coatings used on metal roofs such as galvanized iron. Matte coatings for roofs are required to have a consistent matte appearance regardless of the angle at which they are observed. Conventional matte coatings are generally evaluated based on 60-degree gloss. In contrast, roof coatings are required to have inconspicuous gloss variations, especially in oblique light. In other words, evaluating a matte appearance based solely on 60-degree gloss may not be appropriate. Furthermore, when roof coatings are applied by hand using a roller or the like, it is difficult to achieve a completely uniform film thickness to prevent gloss variations at the joints where the coating becomes thicker. Therefore, a uniform matte appearance is required regardless of film thickness.

[0005] When conventional matte coating films are used as matte coating films for roofs, it is difficult to satisfy the above requirements, and the development of a new matte coating film for roofs has been desired.

[0006] The present invention has been made in view of the above, and aims to provide a matte coating film for roofs that provides a matte effect in oblique light and that provides a uniform matte appearance regardless of the angle at which it is observed or the film thickness. [Means for solving the problem]

[0007] The present disclosure relates to a matte coating film for roofs, in which the difference (Δ60G) between the 60° specular gloss of a dry coating film having a thickness of 30 μm or more and 40 μm or less and the 60° specular gloss of a dry coating film having a thickness of 60 μm or more and 80 μm or less is less than 5, the 85° specular gloss of a dry coating film having a thickness of 30 μm or more and 40 μm or less is 20 or more and 40 or less, and the difference (Δ85G) between the 85° specular gloss of a dry coating film having a thickness of 30 μm or more and 40 μm or less and the 85° specular gloss of a dry coating film having a thickness of 60 μm or more and 80 μm or less is less than 15. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a matte coating film for roofs which provides a matte effect in oblique light and a uniform matte appearance regardless of the angle at which it is observed or the film thickness. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the description of the following embodiments.

[0010] [Matte coating] The matte coating film according to this embodiment is a matte coating film for roofs. The roof on which the matte coating film is formed is not particularly limited, but examples thereof include roofs installed on structures installed outdoors, such as metal roofs made of galvanized iron or steel sheet. Metal roofs have a coating film formed on their surface to prevent corrosion and the like. Furthermore, if the coating film deteriorates, it must be repainted. The matte coating film according to this embodiment may be a coating film formed in advance on the surface of a roof, or may be a coating film obtained by repainting an existing coating film.

[0011] The matte coating film according to this embodiment has a dry coating film thickness of 30 μm to 40 μm and has an 85-degree specular gloss of 20 to 40. This provides a matte effect to the coating film when exposed to oblique light. In other words, even when a person views light incident at an acute angle on the matte coating film formed on the roof surface, a desirable matte effect is obtained.

[0012] In the matte coating film according to this embodiment, the difference (Δ60G) between the 60 degree specular gloss (60Ga) of a dry coating film having a thickness of 60 μm or more and 80 μm or less and the 60 degree specular gloss (60Gb) of a dry coating film having a thickness of 30 μm or more and 40 μm or less is less than 5. This relationship is expressed by the following formula (1). (Δ60G) = (60Ga) - (60Gb) < 5 (1)

[0013] In the matte coating film according to this embodiment, the difference (Δ85G) between the 85 degree specular gloss (85Ga) of a dry coating film having a thickness of 60 μm to 80 μm and the 85 degree specular gloss (85Gb) of a dry coating film having a thickness of 30 μm to 40 μm is less than 15. This relationship is expressed by the following formula (2): (Δ85G) = (85Ga) - (85Gb) < 15 (2)

[0014] The matte coating film according to this embodiment satisfies both the conditions of the above formulas (1) and (2), thereby achieving a uniform matte appearance regardless of the viewing angle and film thickness. A dry coating film having a thickness of 30 μm to 40 μm is the thickness of a dry coating film that is normally assumed. In contrast, a dry coating film having a thickness of 60 μm to 80 μm is twice the thickness. When forming a matte coating film by manually applying paint using a roller or the like, it is expected that some of the painted areas will overlap. In other words, it is expected that the film thickness of the dry coating film will be up to twice as thick in some areas as in other areas. The matte coating film according to this embodiment achieves a uniform matte appearance even when the film thickness is uneven.

[0015] In this specification and claims, the 85-degree specular gloss and the 60-degree specular gloss are values ​​measured in accordance with the "specular gloss" specified in JIS K5600 4-7.

[0016] The matte coating film according to this embodiment preferably contains at least two types of porous amorphous silica, (S1) and (S2).

[0017] In this specification and claims, non-porous crystalline silica is a general term for silicon dioxide (SiO2) in a solid state in which atoms (or molecules) are aggregated without forming crystals with an ordered spatial arrangement, and which has microscopic pores, and is typified by silica gel, precipitated silica, and fumed silica.

[0018] The average particle size (D50) of the porous amorphous silica (S1) is preferably 1 μm or more and 4 μm or less. The average particle size (D50) of the porous amorphous silica (S2) is preferably 4 μm or more and 7 μm or less. The mass ratio of (S1) to the total mass of (S1) and (S2) is preferably 35 mass% or more and 70 mass% or less. This provides a matte effect to the coating film when illuminated obliquely, and a uniform matte appearance is obtained regardless of the angle of observation or film thickness. Although the reason for this effect is unclear, it is believed that the combination of two types of porous amorphous silica with different particle sizes forms a dense round, resulting in a uniform matte appearance regardless of the angle of observation. Furthermore, it is believed that the inclusion of the porous amorphous silica (S1) in the matte coating film can reduce the 60° specular gloss, and the inclusion of the porous amorphous silica (S2) can reduce the 85° specular gloss.

[0019] The porous amorphous silica (S1) and (S2) preferably have an oil absorption of 200 or more and 350 or less (oil absorption unit: ml / 100 g). This reduces the mass per particle of the porous amorphous silica (S1) and (S2), allowing for an increase in the number of silica particles per mass. This allows for a matte coating film that is less susceptible to film thickness fluctuations to be obtained. Furthermore, by suppressing the mass proportion of silica, the handleability of the composition and the water resistance of the coating film can be maintained.

[0020] The matte coating film according to this embodiment preferably further comprises porous amorphous silica (S3) in addition to the porous amorphous silica (S1) and (S2). The porous amorphous silica (S3) is surface-treated, and preferably has an average particle size (D50) of 1 μm or more and 7 μm or less. Examples of surface treatments include MgF2 treatment, inorganic treatment, and hydrophobic treatment. The oil absorption of such porous amorphous silica (S3) is, for example, 150 or more and 250 or less (oil absorption unit: ml / 100 g).

[0021] The porous amorphous silica (S3) contained in the matte coating film improves the water resistance of the matte coating film, thereby achieving favorable performance as a matte coating film for roofs. The content of the porous amorphous silica (S3) in the matte coating film is preferably 2.4 to 5.0 mass%.

[0022] From the viewpoint of improving the water resistance of the coating film, the porous amorphous silica (S1) and (S2) may be surface-treated like the porous amorphous silica (S3), but they may not be surface-treated. If the porous amorphous silica (S1) and (S2) are surface-treated, it may be difficult to satisfy the conditions for the preferred oil absorption. For example, a combination in which the porous amorphous silica (S1) and (S2) are not surface-treated and the porous amorphous silica (S3) is surface-treated is preferred.

[0023] The matte coating film according to this embodiment contains a resin component for forming the coating film in addition to the porous amorphous silica. The resin component is not particularly limited, and examples thereof include silicone resin, alkyd resin, urethane resin, epoxy resin, urea resin, fluororesin, and acrylic resin. These resins may be used alone or in combination. Furthermore, resins obtained by copolymerizing multiple types of resins or modified resins may also be used.

[0024] The matte coating film according to this embodiment may contain pigments, additives, and the like in addition to those described above. Examples of pigments include color pigments and extender pigments, and specific examples include inorganic pigments such as titanium dioxide, carbon black, calcium oxide, barium sulfate, silica, clay, talc, and silica sand, as well as organic pigments such as phthalocyanine blue. Examples of additives include dispersants, viscosity modifiers, driers, leveling agents, and anti-sagging agents. The above are examples of pigments, additives, and the like, and are not particularly limited, and conventionally known pigments and additives can be used.

[0025] [Matte paint composition] The matte coating composition used to form the matte coating film according to the above embodiment contains the porous amorphous silica (S1) and (S2). It also preferably contains the porous amorphous silica (S3). The matte coating composition may further contain the resin component, pigment, additive, solvent, etc.

[0026] The above-mentioned matte coating composition may be a one-component coating, or a two-component coating consisting of a base agent and a curing agent. Examples of one-component coatings include coatings containing the resin components described above. Examples of two-component coatings consisting of a base agent and a curing agent include coatings using alkyd resins modified with silicone or the like. The base agent of the above-mentioned coatings may include, for example, a copolymer of at least one of an unsaturated fatty acid and an alkyd resin having an oxidatively polymerizable group, an acrylic copolymer, and silicone. The curing agent of the above-mentioned coatings may include, for example, a polyisocyanate and a silane coupling agent.

[0027] [Matte coating film formation method] The method for forming a matte coating film according to the embodiment includes a coating step of coating the matte coating composition on the roof surface of a building. The roofing material in this embodiment is not particularly limited, but examples thereof include metal roofs of buildings such as houses. Examples of such metal roofs include, but are not particularly limited to, galvanized iron roofs and steel roofs. Furthermore, metal roofs include coating films applied on these roofing materials.

[0028] The method for applying the coating composition is not particularly limited, but a manual application method using a brush, roller, spray, or the like is preferred. This allows a coating film of the desired thickness to be formed. Furthermore, the matte coating film according to this embodiment can obtain a uniform matte appearance even if there is some variation in the film thickness.

[0029] When a coating film formed on a roof surface is to be repainted, a step of removing the coating film and rust originally formed on the roof surface and a step of polishing the roof surface may be carried out prior to the painting step. The above-mentioned methods are not particularly limited, and known methods can be used.

[0030] Before the step of applying the above-mentioned matte coating composition, a step of applying a primer coating to the roof surface may be carried out. As the primer coating, known paints can be used.

[0031] After the painting process, the roof to which the paint has been applied is cured for a predetermined period of time, thereby forming a matte coating film on the surface of the roof. The curing conditions are not particularly limited, and the roof to which the paint has been applied can be left under natural conditions, for example.

[0032] While the preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments and can be modified within the scope of the present invention. [Example]

[0033] Examples of the present invention will be described below, but the present invention is not limited to these examples.

[0034] [Preparation of Matte Paint Composition] Example 1 The matte coating composition of Example 1 was prepared according to the formulation shown in Table 1. In the following tables, unless otherwise specified, the numerical values ​​indicating the contents in the tables refer to parts by mass.

[0035] [Table 1]

[0036] The details of the raw materials shown in Table 1 are as follows:

[0037] Acrylic resin: Haliacron 8006 (Harima Chemicals, non-volatile content 50±1%, acid value 5 or less), Haliacron 8283 (Harima Chemicals, non-volatile content 54.5±1.5%, acid value 3 or less) Viscosity modifier: fatty acid amide paste, organic bentonite Color pigments: carbon black, yellow iron oxide, ferric oxide, titanium oxide Extender pigment: barium sulfate Solvent: C10 aromatic hydrocarbon, mineral spirits Additives: drier, defoamer, anti-skinning agent

[0038] (Other Examples and Comparative Examples) For the other examples and comparative examples, matte coating compositions for each example and comparative example were prepared using the same method and blending ratio as in Example 1, except that the content of porous amorphous silica was as shown in Table 2 below.

[0039] [Table 2]

[0040] The type and properties of the silica used in each table are listed below.

[0041] <Porous amorphous silica (S1)> S1-a: Nipsil E-220A, average particle size: 1.5 μm, oil absorption: 230 ml / 100 g, untreated, manufactured by Tosoh Silica Corporation S1-b: SYLYSIA 320 Average particle size: 3.2μm, oil absorption: 330ml / 100g, untreated, manufactured by Fuji Silysia Chemical Co., Ltd. S1-c:SYLYSIA 350 Average particle size: 3.9μm, oil absorption: 320ml / 100g, untreated, manufactured by Fuji Silysia Chemical Co., Ltd.

[0042] <Porous amorphous silica (S2)> S2-a: Nipgel AZ-6A0, average particle size: 4.5 μm, oil absorption: 315 ml / 100 g, untreated, manufactured by Tosoh Silica Corporation S2-b: Nipgel BY-601, average particle size: 5.0 μm, oil absorption: 205 ml / 100 g, untreated, manufactured by Tosoh Silica Corporation S2-c:SYLYSIA 440 6.2μm, oil absorption: 220ml / 100g, untreated, manufactured by Fuji Silysia Chemical Co., Ltd. S2-d:SYLYSIA 370 6.4μm, oil absorption: 280ml / 100g, untreated, manufactured by Fuji Silysia Chemical Co., Ltd.

[0043] <Porous amorphous silica (S3)> S3-a: SYLYSIA 445 6.17 μm, oil absorption: 220 ml / 100 g, MgF2 treated, Fuji Silysia Chemical Ltd. S3-b: Silophorbic 704 6.2 μm, oil absorption: 170 ml / 100 g, hydrophobic treatment, Fuji Silysia Chemical Ltd.

[0044] <Other Silica> SX:SYLYSIA 450 Average particle size: 8.0μm, oil absorption: 220ml / 100g, untreated, manufactured by Fuji Silysia Chemical Co., Ltd.

[0045] Gloss Value (Matte coating production) The matte coating compositions of each Example and Comparative Example were applied to art paper as a substrate using a 6 mil (150 μm) applicator and aged at 23° C. for 3 days to produce a dried coating film with a thickness of 30 μm to 40 μm. In the same manner, coating was performed using a 12 mil (300 μm) applicator to produce a dried coating film with a thickness of 60 μm to 80 μm.

[0046] (Gloss value measurement) The 60-degree specular gloss and 85-degree specular gloss of the dried coating film prepared above were measured in accordance with the "specular gloss" specified in JIS K5600 4-7. A three-angle gloss meter, MULTI GLOSS268A (manufactured by KONICA MINOLTA), was used for the measurements. The results are shown in Table 3. Dry coating films with a film thickness of 30 μm or more and 40 μm or less: 6 mil gloss, and dry coating films with a film thickness of 60 μm or more and 80 μm or less: 12 mil gloss. The difference in 6 mil gloss from 12 mil gloss is shown in Table 3 as "6 mil vs. 12 mil gloss difference."

[0047] (Evaluation: Coating gloss (oblique light)) Those having a 6 mil gloss of 20 or more and 40 or less at 85-degree specular gloss were rated as pass (◯), and those outside the above range were rated as fail (×). The results are shown in Table 3.

[0048] (Evaluation: Gloss dependence on film thickness (general)) In the 60-degree specular gloss, a difference in gloss between 6 mil and 12 mil of less than 5 was evaluated as pass (◯), and a difference outside the above range was evaluated as fail (×). The results are shown in Table 3.

[0049] (Evaluation: Gloss dependence on film thickness (oblique light)) In the 85-degree specular gloss test, a difference in gloss between 6 mil and 12 mil of less than 15 was evaluated as pass (◯), and a difference outside the above range was evaluated as fail (×). The results are shown in Table 3.

[0050] [water resistance] (Matte coating production) A 7 x 15 cm galvanized iron plate (#320 polished) was used as the substrate, and after applying a primer paint (one-component Hi-Pon Fine Decro, manufactured by Nippon Paint Co., Ltd.) to the surface of the substrate, the matte paint composition of each Example and Comparative Example was applied under the following conditions: First, the matte paint composition was diluted 10% with paint thinner A (manufactured by Nippon Paint Co., Ltd.). Then, a coating amount of 100±10 g / m was applied. 2 The coating was applied twice by brush painting, and then aged at 23°C for 7 days to obtain substrates on which matte coating films according to the examples and comparative examples were formed.

[0051] (Water resistance test and evaluation) After coating, each substrate was submerged in water at 23°C for 7 days. One minute after removal from the water, and three hours later, coating adhesion was evaluated using the adhesion test specified in JIS K 5600-5-6 (cross-cut method: grid, 4 mm, 25 squares). Of the JIS K 5600-5-6 classifications 0 to 5, classifications 0 to 2 were considered pass, and anything outside the above range was considered fail. Evaluation was based on the following criteria. The results are shown in Table 3.

[0052] (Evaluation criteria) 〇 The evaluation one minute after lifting meets the passing criteria (capable of adapting to extremely harsh external environments). △ The evaluation one minute after being pulled up does not meet the pass criteria, but the evaluation three hours after being pulled up meets the pass criteria (it is possible to adapt to the external environment). × The passing criteria are not met either 1 minute or 3 minutes after being pulled up (unable to adapt to the external environment).

[0053] [Finishing quality] (Matte coating production) A 4 x 90 cm Bonded steel plate was used as the substrate. After a primer (one-component Hi-Pon Fine Decro, manufactured by Nippon Paint Co., Ltd.) was applied to the surface of the substrate, the matte paint composition according to each Example and Comparative Example was applied under the following conditions: First, the matte paint composition was diluted to 15% with paint thinner A (manufactured by Nippon Paint Co., Ltd.). Then, a coating amount of 100±10 g / m was applied. 2 The coating was applied twice, by brush and roller. Specifically, the periphery of the substrate was painted with a brush, the center was painted with a roller, and the center was then patched. The coating was then cured, and the finish was visually evaluated the day after painting according to the following evaluation criteria. ◎ and ○ were considered pass, and △ and × were considered fail. The results are shown in Table 3.

[0054] (Evaluation criteria) ◎ Has a subdued (low) gloss, and there is no noticeable difference in gloss between the joint and its surrounding area. ◯: Has a subdued (low) gloss, and the difference in gloss between the joint and its surrounding area is slight. △: The gloss is somewhat high, or there is a noticeable difference in gloss between the joint and its surrounding area. x: The gloss is high, or there is a significant difference in gloss between the joint and its periphery, or both.

[0055] [Table 3]

[0056] From the results shown in Table 3, it is clear that the matte coating films of each Example provide a matte effect in oblique light, and provide a uniform matte appearance regardless of the viewing angle or film thickness.

Claims

[Claim 1] A matte coating film for roofs, the difference (Δ60G) between the 60-degree specular gloss of a dry coating film having a film thickness of 60 μm or more and 80 μm or less and the 60-degree specular gloss of a dry coating film having a film thickness of 30 μm or more and 40 μm or less is less than 5; The 85-degree specular gloss of a dried coating film having a film thickness of 30 μm or more and 40 μm or less is 20 or more and 40 or less, A matte coating film in which the difference (Δ85G) between the 85 degree specular gloss of a dry coating film having a film thickness of 60 μm or more and 80 μm or less and the 85 degree specular gloss of a dry coating film having a film thickness of 30 μm or more and 40 μm or less is less than 15.

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