JP2012040687A - Exterior sheet, exterior sheet-layered steel plate, and method for producing the exterior sheet-layered steel plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel exterior sheet which is excellent in long-term weather resistance and can keep an antifouling effect even when exposed to rain or the like over a long period of time.SOLUTION: The exterior sheet is obtained by providing a hydrophilic layer to the embossed surface of a base material sheet having the embossed surface and is characterized in that the surface of the exterior sheet has ≤40° water contact angle when immersed in 5% hydrochloric acid for 24 hours. Since the hydrophilic layer has such property that hydrophilicity thereof is enhanced by contact with the rain, particularly, acid rain, the exterior sheet can keep the antifouling effect even when exposed to the rain or the like over a long period of time.

Description

  The present invention relates to an exterior sheet that is used outdoors and exhibits an antifouling effect when exposed to rain, and an exterior sheet laminated steel sheet using the exterior sheet.

  Conventionally, a decorative plate in which a metal plate is coated with polyvinyl chloride has been widely used in various fields such as interior and exterior materials for buildings, electrical products, miscellaneous goods and the like. Among them, a so-called vinyl chloride steel plate obtained by laminating a vinyl chloride sheet on a steel plate is frequently used because it can be embossed and printed and has excellent secondary workability.

  The vinyl chloride sheets used for this type of application have excellent weather resistance, and there is no problem such as deterioration of the sheet itself due to long-term exposure, but the composition contains a large amount of plasticizer and the like. There is a problem that the appearance deteriorates due to the attachment of dripping lines or the like which are thought to be caused by the fact that

  As one of means for solving such a problem, a means for increasing the hydrophilicity of the sheet surface can be mentioned. Specific methods for hydrophilizing the sheet surface include a method of forming a hydrophilic coating layer or modifying the sheet surface.

For example, there is a method of hydrophilizing the surface by adding a surfactant to a urethane resin or acrylic resin dissolved in an organic solvent on the surface of a vinyl chloride sheet.
Surfactants are substances that are used in many fields including detergents and emulsifiers and are indispensable for daily life, and are compounds having both a hydrophilic group and a hydrophobic group in one molecule. It is known that by adding a surfactant to a coating agent, the sheet surface can be hydrophilized by the effect of the hydrophilic group of the surfactant. However, surfactants generally have a low molecular composition and migrate (bleed) to the surface over time and are washed away with rain, so it is difficult to maintain long-term hydrophilicity.

Examples of the surface modification for hydrophilizing the sheet include corona treatment and plasma treatment of the sheet. By subjecting the sheet to corona treatment or plasma treatment, hydrophilic functional groups such as carboxyl groups, carbonyl groups, aldehyde groups, hydroxyl groups, and ether groups are formed on the sheet surface, thereby changing the sheet surface to be hydrophilic. Can do.
Such surface modification can be applied to a vinyl chloride sheet and can impart hydrophilic performance at a low cost. However, in terms of long-term weather resistance, the hydrophilic functional group on the surface changes with time. It is known that it is deactivated and does not show hydrophilicity, and it cannot be said that it is suitable for this assumed use.

In addition, by coating the surface of the vinyl chloride sheet with a photocatalyst, the surface becomes hydrophilic, and it is possible to impart antifouling properties due to the decomposition effect of the photocatalyst. A photocatalyst coating agent using titanium oxide is known as a photocatalyst (Patent Document 1).
It is known that the surface is highly hydrophilized in response to photoexcitation of the photocatalyst. By forming the photocatalyst layer on the sheet surface, antifouling effect due to hydrophilicity can be expected on the sheet. Further, since the adhered dirt can be decomposed by the photocatalytic effect, a higher antifouling effect can be expected. However, if the photocatalyst layer is formed directly on the sheet, not only the dirt adhered by the photocatalytic effect but also the sheet itself is decomposed, which is not preferable from the viewpoint of long-term weather resistance. In order to separate the sheet and the photocatalyst layer, it is possible to perform a method such as forming a primer coat on the sheet surface and then forming a photocatalyst layer, but the photocatalyst coating agent is generally expensive and the primer There is a problem that the number of steps for forming the coat is further disadvantageous in terms of cost.

Japanese Patent Application No. 8-528290

  Therefore, the present invention is excellent in long-term weather resistance, can maintain an antifouling effect even when exposed to rain for a long time, and preferably provides a new exterior sheet that does not contain a photocatalyst. It is.

  The present invention is an exterior sheet in which a hydrophilic layer is provided on an embossed surface of a base sheet having an embossed surface, and the water contact angle of the surface after being immersed in 5% hydrochloric acid for 24 hours is 40 ° or less. The exterior sheet | seat characterized by this is proposed.

Since the hydrophilic layer of the exterior sheet of the present invention has the property of increasing hydrophilicity by contact with rain, particularly acid rain, it has excellent long-term weather resistance, and even when exposed to rain for a long time. Antifouling effect can be maintained.
Such a hydrophilic layer can be formed, for example, by applying a coating agent containing an acrylic resin as a binder and containing 5 to 20 wt% of a fluorine silicate compound as a solid content, and blending a photocatalyst. One of the features is that it can be formed without any problems.
Therefore, the exterior sheet of the present invention is particularly suitable as an exterior sheet used for a building exterior material. For example, an exterior sheet-laminated steel sheet can be produced by laminating on a steel sheet.

  Hereinafter, an example of an embodiment of the present invention will be described, but the scope of the present invention is not limited to the embodiment described below.

<Exterior sheet>
An exterior sheet according to an example of the present embodiment (hereinafter referred to as “external exterior sheet”) is an exterior sheet formed by forming a hydrophilic layer on an embossed surface of a base sheet having an embossed surface.

<Base material sheet>
As the base sheet of the exterior sheet, for example, a sheet mainly composed of various resins such as acrylic, polycarbonate, polyester, and vinyl chloride can be used. Among these, a vinyl chloride sheet containing a vinyl chloride resin as a main component is preferable from the viewpoint of excellent weather resistance and low cost. As the vinyl chloride sheet, a commercially available vinyl chloride sheet can be used.

(Embossed surface)
In this exterior sheet, it is important to provide a hydrophilic layer on the embossed surface after the surface of the base material sheet is used as an embossed surface. Compared with the case where a hydrophilic layer is formed without providing an embossed surface, the hydrophilicity can be significantly increased.
Normally, when embossing is formed on the surface of a sheet such as a vinyl chloride sheet, the contact area with water increases, and on the contrary, there is a tendency to become water-repellent. It has been found that the hydrophilicity can be remarkably enhanced by providing a hydrophilic layer on the embossed surface.

Regarding the surface roughness of the embossed surface, Ra (centerline average roughness) is preferably 1 μm or more and 10 μm or less, Rz (maximum height) is preferably 5 μm or more and 20 μm or less, and Rz JIS (10 Point average roughness): preferably 10 μm or more and 20 μm or less, and Rp (average depth): 2 μm or more and 10 μm or less is preferable.
Further, the glossiness (gloss) is 50% or less, particularly 30% or less, and more preferably 10% or less.

Here, Ra (center line average roughness), Rz (maximum height), Rz JIS (ten-point average roughness), Rp (average depth) are JISB0601 (geometric characteristic specification of product (GPS) -surface properties. : Contour Curve Method—Terminology, Definition and Surface Property Parameters), for example, using a SE-3FK tester manufactured by Kosaka Laboratory Ltd. and using a 2 μm R diamond needle. .
The glossiness is measured according to JISZ8741-1997 (mirror glossiness-measuring method), and can be measured using, for example, a UGV-5DP tester manufactured by Suga Test Instruments Co., Ltd. The incident angle of the light source in the gloss measurement is set to 60 °.

  As a method for forming such an embossed surface on the surface of the base sheet, for example, the base sheet may be brought into contact with an embossing roll. As a specific example, after passing through a heating roll and a take-off roll, after being heat-treated with an infrared heater, it may be sent to a nip roll, an embossing roll, and a cooling roll.

<Hydrophilic layer>
The hydrophilic layer in the exterior sheet is preferably formed of a solvent-soluble coating agent that can be formed at a low temperature in order not to lose the embossed surface.
Specifically, it is preferably formed by applying a solvent-soluble coating agent containing a binder and a hydrophilizing agent and, if necessary, a curing agent or a curing catalyst to the embossed surface of the base sheet. When forming a hydrophilic layer, if it is subjected to a high temperature drying treatment, the embossed surface may be lost.

In addition, the hydrophilic layer in the exterior sheet has a property of increasing hydrophilicity when contacted with water, preferably an acidic liquid, and has a property of increasing hydrophilicity when contacted with rain, particularly acidic rain. Is a layer.
As an evaluation for judging the presence or absence of such characteristics, it can be evaluated by an accelerated test in which the water contact angle of the surface after being immersed in 5% hydrochloric acid for 24 hours is measured as follows.

That is, it is important that the exterior sheet has a water contact angle of 40 ° or less after being immersed in 5% hydrochloric acid for 24 hours. If the said water contact angle is 40 degrees or less, hydrophilic property will increase by contacting with rain, especially acid rain, and the antifouling effect can be exhibited. If the water contact angle is further reduced, further effects can be expected. Therefore, the water contact angle is more preferably 35 ° or less, and even more preferably 30 ° or less.
From another point of view, the water contact angle of the surface after being immersed in 5% hydrochloric acid for 24 hours is 40% or less, especially 45% or less, especially 50% or less. Is more preferable.

(Binder resin)
Preferable examples of the binder resin include an acrylic polyol resin, an acrylic silicone resin, a fluorine-containing silicone resin, a urethane resin and the like that are soluble in a solvent and contain a hydroxyl group and / or a carboxyl group. Among these, acrylic resins are preferable from the viewpoint of exterior use and cost.

  Examples of acrylic resins include acrylic, alkyl acrylate, alkyl methacrylate (alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, 2-ethylhexyl. Group, lauryl group, stearyl group, cyclohexyl group, etc.), and monomers having a crosslinkable functional group, such as carboxyl group, methylol group, acid anhydride group, sulfonic acid group, amide group, or methylolated amide group, amino It is preferable to include a monomer having a functional group such as a group (including a substituted amino group), an alkylolated amino group, a hydroxyl group, and an epoxy group.

Examples of monomers having the above functional groups include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, vinyl sulfonic acid, styrene sulfonic acid, acrylamide, methacrylamide, N-methyl methacrylamide, methylolated acrylamide. , Methylolated methacrylamide, diethylaminoethyl vinyl ether, 2-aminoethyl vinyl ether, 3-aminopropyl vinyl ether, 2-aminobutyl vinyl ether, dimethylaminoethyl methacrylate, and methylolated amino group, β-hydroxyethyl acrylate, β -Hydroxyethyl methacrylate, β-hydroxypropyl acrylate, β-hydroxypropyl methacrylate, β-hydroxy vinyl ether, 5-hydroxy Examples include pentyl vinyl ether, 6-hydroxyhexyl vinyl ether, polyethylene glycol monoacrylate, polyethylene glycol monomethacrylate, glycidyl acrylate, and glycidyl methacrylate. However, it is not necessarily limited to these.
In addition to the above, the following monomers such as acrylonitrile, methacrylonitrile, styrene, butyl vinyl ether, mono- or dialkyl esters of maleic acid and itaconic acid, methyl vinyl ketone, vinyl chloride, vinylidene chloride, vinyl acetate, vinyl pyridine, Vinylpyrrolidone, alkoxysilane having a vinyl group, polyester having an unsaturated bond, and the like may be used as a copolymerization component.

(Curing agent)
As a hardening | curing agent, an isocyanate compound, a block isocyanate compound, a melamine resin, a dibasic acid, a silane compound, an epoxy resin etc. can be used, for example. Among these, an isocyanate compound is preferable from the viewpoint of weather resistance and the like.

As the isocyanate compound, a compound having two or more isocyanate groups is preferable.
For example, the diisocyanate compound having two isocyanate groups is conventionally known and is not particularly limited. For example, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, xylene-1,4-diisocyanate, xylene- 1,3-diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylether diisocyanate, 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, naphthylene-1,4-diisocyanate, naphthylene-1,5-diisocyanate, 3,3'-dimethoxydiphenyl-4,4'-diisocyanate, tetramethylxylylene Aromatic diisocyanates such as diisocyanate, polyphenylene polymethylene polyisocyanate, carbodiimide modified product of 4,4'-diphenylmethane diisocyanate, uretonimine modified product, tetramethylene diisocyanate, hexamethylene diisocyanate, 2-methylpentane-1,5-diisocyanate, lysine diisocyanate Aliphatic diisocyanates such as aliphatic diisocyanate, isophorone diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylene diisocyanate, hydrogenated diphenylmethane diisocyanate and the like. These isocyanurate-modified products, burette-modified products, uretonimine-modified products, carbodiimide-modified products, and the like are also included.

In addition, the polyisocyanate compound having three or more isocyanate groups is a conventionally known one and is not particularly limited. For example, diisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, And adducts of the above diisocyanates, trimerized diisocyanates, and modified burettes obtained by reaction with water.
The above diisocyanate compounds and polyisocyanate compounds may be used alone or in combination of two or more.

(Curing catalyst)
Examples of the curing catalyst include an organic tin compound, an organic acidic phosphate ester, an organic titanate compound, and an aluminum chelate compound.

(Hydrophilic agent)
As the hydrophilizing agent, a silicate compound, particularly a silicate compound having a molecular weight of 250 to 3000 is preferable. If the molecular weight is 250 or more, it is not volatilized by heating when curing the coating film, and if it is 3000 or less, the coating film surface can be sufficiently hydrophilized. The molecular weight can be determined by GPC as mentioned above, and in the case of a commercial product, a value described in product information such as a catalog can be used.

A silicate compound will not be specifically limited if the said molecular weight is satisfy | filled, It can select from the raw material silicate compounds used in order to obtain the said modified silicate.
Among the above silicate compounds, a fluorine-modified silicate compound (also referred to as “fluorine silicate”) is preferable in consideration of the point that it easily comes out on the surface and the hydrophilization proceeds rapidly.

The fluorine silicate compound is a compound obtained by fluorine-modifying a tetraalkoxysilane condensate in the description of the raw material silicate compound. Specific examples of the fluorine silicate include GH-110, GH-700, and the like that are available from Daikin Industries.
Two or more kinds of silicate compounds can be mixed and used as necessary.

  As described above, as the most preferable hydrophilic layer, an acrylic resin is used as a binder, and a solvent-soluble coating agent obtained by blending a fluorine silicate compound is applied thereto, followed by drying at a low temperature, preferably 70 ° C. or less. It is preferable to form it in that the hydrophilicity is excellent while maintaining the embossed surface. A more preferable drying temperature is in the range of 60 to 70 ° C., and the drying time is preferably at least 2 minutes.

  At this time, the fluorine silicate compound is preferably blended in an amount of 5 wt% to 20 wt% in terms of solid content. If the fluorine silicate compound is blended in such a range, sufficient hydrophilicity can be obtained, and the silicate compound is retained in the binder, which is preferable from the viewpoint of maintaining the hydrophilicity of the coating film. From this point of view, the fluorine silicate compound is more preferably blended at a solid content of 5 wt% or more, or 15 wt% or less, and more preferably 5 wt% or more, or 10 wt% or less.

(Si ratio of hydrophilic layer)
The hydrophilic layer preferably contains 10 at% (atomic%) or more of Si with respect to the elemental composition ratio of the surface. If the surface of the hydrophilic layer contains 10 at% or more of Si, sufficient hydrophilicity can be obtained, so that an excellent antifouling function can be obtained, and this tendency further increases as the Si ratio increases. Therefore, the surface of the hydrophilic layer further preferably contains 12 at% or more of Si, and more preferably contains 15 at% or more.

(Hydrophilic layer thickness)
The thickness of the hydrophilic layer is preferably 1 μm to 10 μm, particularly preferably 3 μm to 7 μm, from the viewpoint of low glossiness, processability, durability, cost, and the like.

<Application>
This exterior sheet is exposed to rain, particularly acid rain for a long period of time, thereby causing a hydrolysis reaction to exhibit hydrophilicity and maintain an antifouling effect. It is particularly suitable as a sheet for use.

  The exterior sheet can be processed as it is to produce a product, or can be laminated on a steel sheet to produce a product as an exterior sheet-laminated steel sheet.

In order to manufacture a laminated sheet steel sheet for an exterior, for example, the embossed surface of a base sheet formed with emboss is coated with a solvent-soluble coating agent containing a fluorine silicate compound and dried at 70 ° C. or lower to make hydrophilic. What is necessary is just to manufacture by once forming the sheet | seat for exteriors made to form a layer, and laminating | stacking to a steel plate further. However, it is not limited to this manufacturing method.
A more preferable drying temperature is in the range of 60 to 70 ° C., and the drying time is preferably at least 2 minutes.

<Explanation of terms>
In the present invention, the “main component” includes the meaning of allowing other components to be contained within a range that does not interfere with the function of the main component, unless otherwise specified. At this time, the content ratio of the main component is not specified, but the main component (when two or more components are main components, the total amount thereof) is 50% by mass or more, particularly 70% by mass in the composition. %, More preferably 90% by mass or more (including 100%).

  In general, “sheet” is a thin product as defined by JIS and generally has a thickness that is small and flat instead of length and width. In general, “film” refers to length and width. A thin flat product having an extremely small thickness and an arbitrarily limited maximum thickness, usually supplied in the form of a roll (Japanese Industrial Standard JISK6900). For example, in terms of thickness, in the narrow sense, a film having a thickness of 100 μm or more is sometimes referred to as a sheet, and a film having a thickness of less than 100 μm is sometimes referred to as a film. However, since the boundary between the sheet and the film is not clear and it is not necessary to distinguish the two in terms of the present invention, in the present invention, even when the term “film” is used, the term “sheet” is included and the term “sheet” is used. In some cases, “film” is included.

In the present invention, when expressed as “X to Y” (X and Y are arbitrary numbers), “X is preferably greater than X” and “preferably Y”, with the meaning of “X to Y” unless otherwise specified. It means “smaller”.
Further, in the present invention, when expressed as “X or more” (X is an arbitrary number), it means “preferably larger than X” unless otherwise specified, and “Y or less” (Y is an arbitrary number). ) Includes the meaning of “preferably smaller than Y” unless otherwise specified.

  The present invention will be described more specifically with reference to the following examples. However, the following examples are not intended to limit the present invention, and all modifications can be made without departing from the spirit of the following description. It is included in the technical scope.

  First, raw materials used in the following examples, comparative examples, and reference examples will be described.

(1) Substrate sheet As a substrate sheet, 100 parts by mass of vinyl chloride resin having an average polymerization degree of 1000, 30 parts by mass of a plasticizer, other stabilizers and pigments are mixed in an appropriate amount, and this mixture is calendered. Thus, a sheet formed into a sheet having a thickness of 250 μm was used.
Further, this sheet was passed between a pair of rolls heated to 100 ° C. in which embossed patterns with an approximately 80 μm pitch and 80 μm depth were engraved on one roll surface to form an embossed surface.
The embossed surface thus formed was Ra: 2.3 μm, Rz: 12.0 μm, Rz JIS: 14.1 μm, Rp: 4.6 μm, and gloss: 7% or less.

(2) Coating agent Coating agent 1: Acrylic coating agent (“Udouble C3600” manufactured by Nippon Shokubai Co., Ltd.) 10.00 g, isocyanate curing agent (Asahi Kasei Co., Ltd., TPA-100) 0.78 g, diluting solvent (MEK) 9. 15g mixed and stirred.
Coating agent 2: Mixing 10.00 g of acrylic silicone coating agent (“Zemlac 5920B” manufactured by Kaneka), 2.00 g of aluminum chelate curing catalyst (CAT-101 manufactured by Kaneka), and 11.3 g of diluting solvent (MEK) -Stirred.

(3) Hydrophilizing agent Fluorosilicate-based hydrophilizing agent A: Fluorine-modified silicate ("Zeffle GH701" manufactured by Daikin, molecular weight 1200)
Alkyl silicate hydrophilizing agent B: Alkyl silicate ("MS-57" manufactured by Mitsubishi Chemical Corporation, molecular weight 1400)

  Next, the test method performed for performance evaluation is shown first.

(4) Blocking property After forming a coating layer on the surface of the sheet (sample) obtained in the examples and comparative examples, the coating layer is wound on the back surface and cured at 40 ° C. for 3 days, and then blocking property according to the following criteria. Evaluated.
○: Blocking did not occur.
X: Blocking occurred.

(5) Appearance After forming a coat layer on the sheets (samples) obtained in Examples and Comparative Examples, appearance defects such as deterioration in appearance due to emboss return due to drying of the coat layer were visually observed and evaluated according to the following criteria: did.
X: Appearance defects such as deterioration in appearance due to emboss return due to drying of the coating layer were observed.
○: There was no problem in appearance.

(6) Surface Si amount The surface elemental composition ratio of the surface of the sheet (sample) obtained in Examples and Comparative Examples was measured by an X-ray photoelectron analyzer (ESCA), and the amount of Si in the surface layer was calculated. .

(7) Initial water contact angle After the surfaces of the sheets (samples) obtained in Examples and Comparative Examples were washed with ethanol, standard water (72 mN / m) was dropped onto the surface in an environment of 23 ° C. × 50%. Then, after 30 seconds, the contact angle with water was measured using a contact angle meter for water (“FACECA-X type” manufactured by Kyowa Interface Science Co., Ltd.).

(8) Water contact angle after immersion in hydrochloric acid Sheets (samples) obtained in Examples and Comparative Examples were immersed in 5% hydrochloric acid (room temperature) for 24 hours, and the samples after immersion were washed with running water, and then 23 ° C. × 50%. Standard water (72 mN / m) was dropped on the surface under the environment, and 30 seconds later, contact with water using a water contact angle measuring instrument (“FACECA-X type” manufactured by Kyowa Interface Science Co., Ltd.) The corner was measured.

(9) Appearance evaluation after exposure for 3 months Sheets (samples) obtained in Examples and Comparative Examples were coated with an acrylic adhesive and thermally laminated on a steel sheet passed through a drying furnace at 300 ° C. to prepare a test sample. . This test sample was placed directly under the corrugated sheet outdoors, and an exposure test was conducted for 3 months. After 3 months, the state of the sample surface was visually confirmed and evaluated according to the following criteria.

○: No raindrops are observed.
Δ: Some raindrops are seen.
X: Significant raindrops are observed.

<Example 1>
A coating composition was prepared by adding 5 wt% of the fluorosilicate hydrophilizing agent A to the coating agent 1 in a solid content ratio.
The coating composition was applied to the embossed surface of the substrate sheet (250 μm thick vinyl chloride sheet) with a # 10 bar coater to form a coating layer, and dried at 60 ° C. for 2 minutes. The coat thickness was about 3 μm as a result of measurement with a contact-type thickness measuring machine. After drying, the coated surface and the back surface of the vinyl chloride sheet were overlapped and cured at 40 ° C. for 3 days to obtain a sheet (sample).
After curing, the coating layer adhesion, appearance, surface Si amount, initial water contact angle, and water contact angle after immersion in hydrochloric acid were measured. The samples were exposed outdoors for 3 months, and the antifouling property after the exposure test was evaluated. Table 1 shows the test results.

<Example 2>
A sheet (sample) was produced in the same manner as in Example 1 except that the drying temperature was 70 ° C. × 2 minutes.

<Example 3>
A sheet (sample) was produced in the same manner as in Example 1 except that 10 wt% of the fluorinated silicate hydrophilizing agent A was added and the drying temperature was 70 ° C. × 2 minutes.

<Example 4>
A sheet (sample) was prepared in the same manner as in Example 1 except that the coating agent 2 was used as the coating agent and the drying temperature was 70 ° C. × 2 minutes.

<Reference Example 1>
A sheet (sample) in which a coating layer was not provided on a vinyl chloride sheet was prepared and used as Reference Example 1.

<Comparative Example 1>
A sheet (sample) was prepared in the same manner as in Example 1 except that the fluorine silicate hydrophilizing agent A was not added to the coating agent 1.

<Comparative example 2>
A sheet (sample) was produced in the same manner as in Example 1 except that 2 wt% of the fluorinated silicate hydrophilizing agent A was added.

<Comparative Example 3>
A sheet (sample) was prepared in the same manner as in Example 1 except that the coating agent 2 was used as the coating agent and the fluorinated silicate hydrophilizing agent A was not added.

<Comparative example 4>
A sheet (sample) was prepared in the same manner as in Example 1 except that the fluorine silicate hydrophilizing agent A was not added to the coating agent 1 and the alkyl silicate hydrophilizing agent B was added in an amount of 5 wt% instead. .

(Discussion)
From these results, at least the sheet according to Example 1-4 becomes hydrophilic when the hydrophilic layer comes into contact with the acidic liquid, and the water contact angle is 40 ° in the accelerated test in which the sheet is immersed in 5% hydrochloric acid for 24 hours. I found out that And if it is such a sheet | seat, ie, the exterior sheet | seat which provides the said hydrophilic layer in the embossed surface of the base material sheet provided with the embossed surface, it will maintain the outstanding antifouling effect also in a 3-month exposure test Turned out to be possible.
As the degree to which the hydrophilicity is increased, it is preferable that the water contact angle of the surface after being immersed in 5% hydrochloric acid for 24 hours is 40% or less as compared with that before immersion, from the present example and the test results so far. Can think.
Such an effect is due to the hydrophilic layer of the present exterior sheet being hydrolyzed by contact with the acidic liquid to increase the hydrophilicity of the surface layer and the surface layer being formed on the embossed surface. This can be attributed to a synergistic effect.

Claims (9)

  An exterior sheet having a hydrophilic layer provided on an embossed surface of a base sheet having an embossed surface, wherein the surface has a water contact angle of 40 ° or less after being immersed in 5% hydrochloric acid for 24 hours. Sheet for exterior.   The exterior sheet according to claim 1, wherein the hydrophilic layer has a surface water contact angle of 40% or less after immersion in 5% hydrochloric acid for 24 hours.   The exterior sheet according to claim 1, wherein the hydrophilic layer contains a fluorine silicate compound.   The exterior sheet according to any one of claims 1 to 3, wherein the element composition ratio of the surface of the hydrophilic layer is such that the element composition ratio of Si is 10 at% or more.   The exterior sheet according to any one of claims 1 to 4, wherein the hydrophilic layer contains an acrylic resin as a binder and contains a fluorine silicate compound in a solid content of 5 wt% to 20 wt%.   The exterior sheet according to any one of claims 1 to 5, wherein the base sheet contains a vinyl chloride resin as a main component.   The embossed surface of a base sheet provided with an embossed surface is coated with a solvent-soluble coating agent containing a fluorine silicate compound and dried at 70 ° C or lower to form a hydrophilic layer. A method for producing an exterior sheet according to any one of the above.   An exterior sheet-laminated steel sheet obtained by laminating the exterior sheet according to claim 1 on a steel sheet.   The exterior sheet was formed once by coating the embossed surface of the base sheet with the embossed surface with a solvent-soluble coating agent containing a fluorine silicate compound and drying at 70 ° C. or lower to form a hydrophilic layer. Then, the manufacturing method of the laminated sheet steel for exterior sheets characterized by laminating this exterior sheet on a steel plate.