JP2006233073A - Photocatalytic coating, and steel plate and tent cloth each coated with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photocatalytic coating that is imparted with prescribed photocatalytic functions, has a shortened curing time after coating, gives a cured coating film not decomposed by photocatalytic actions, and exhibits flexibility, and to provide a steel plate and a tent cloth suffering from no peeling of the coating film even when bent after coated with the photocatalytic coating. <P>SOLUTION: The photocatalytic coating comprises Nafion (R) as an organic resin binder that is not decomposed by photocatalytic actions and exhibits flexibility after dried and cured. The steel plate and the tent cloth are each coated with the coating. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a photocatalyst coating containing a metal oxide having a photocatalytic function, a steel plate coated with the coating, and a tent.

  Recently, a photocatalyst coating containing a metal oxide having a photocatalytic function excellent in stain resistance and antibacterial properties has attracted attention.

  In addition, the paint used for the coating of building exterior walls, body steel plates, tents, etc. has a good appearance and is resistant to dirt such as rain-stain stains, that is, contamination resistance (environmental pollution). It is hoped that

  Therefore, a method for effectively using a coating material or a surface treatment material (hereinafter collectively referred to as a paint) having a photocatalytic function that exhibits stain resistance and antibacterial properties and is excellent in hydrophilicity is being sought. Generally, when a metal oxide having a photocatalytic function is blended as a paint, a hydrophilic resin binder (hydrophilic polymer) is usually used in order to sufficiently exhibit a photocatalytic function against environmental dirt.

  Further, the photocatalytic function has a problem that the organic resin binder to be blended as a paint is also decomposed to excite a severe oxidation-reduction reaction and the coating film is deteriorated and durability is inferior.

  Therefore, when blending a photocatalyst paint, a vitreous inorganic binder called silica sol is exclusively used.

  A photocatalyst coating material containing silica sol and having excellent dispersion stability has already been filed (for example, see Patent Document 1).

Furthermore, a titanium oxide coating composition in which silica sol is used as a binder and the binder does not deteriorate by photocatalytic action has already been filed (for example, see Patent Document 2).
Japanese Patent Laid-Open No. 11-343426 (page 1-5) JP 2000-73297 A (page 1-12)

  A paint using a silica sol as a binder that does not deteriorate while blending a metal oxide having a photocatalytic function has a problem that it takes a long time to cure.

  In addition, the cured coating film has no flexibility and cannot be applied to a color steel sheet that is bent after coating. Furthermore, it is also unsuitable for use as a tent place paint that is frequently assembled and folded.

  An object of the present invention is to provide a predetermined photocatalytic function in order to eliminate the above-mentioned problems, shorten the curing time after coating, and further prevent the cured coating film from being decomposed by the photocatalytic action, further improving flexibility. Another object of the present invention is to provide a photocatalyst coating material having a steel plate and a tent where the coating film does not peel even if the photocatalyst coating material is applied and then bent.

  In order to achieve the above-mentioned object, the invention according to claim 1 is directed to a metal oxide having a photocatalytic function, which has a molecular chain having a large binding energy and is not decomposed by a photocatalytic action, and has a low intermolecular cohesive force and is dry cured. It is characterized by being a photocatalyst coating compounded later with an organic resin binder having flexibility.

  According to the invention according to claim 1 having the above-described configuration, since the resin binder is not decomposed, the coating film is not deteriorated and has a long life and can exhibit a photocatalytic function for a long time. Moreover, since it has flexibility after drying and curing, a photocatalyst coating material that does not crack or peel off the coating film even when it is bent after coating can be obtained.

  The invention according to claim 2 is characterized in that the resin binder is Nafion (registered trademark) which is polytetrafluoroethylene in which a sulfonic acid group is graft-polymerized.

  According to the invention according to claim 2 having the above-described configuration, Nafion (registered trademark of DuPont) is not decomposed by the photocatalytic function, but also exhibits super hydrophilicity after drying and curing. And a very effective photocatalytic coating.

  The invention according to claim 3 is characterized in that the metal oxide is porous titanium oxide.

  According to the invention according to claim 3 having the above-described configuration, since the titanium oxide is porous, it is possible to form a coating film that can sufficiently exhibit not only the antifouling function but also the deodorizing function.

  The invention according to claim 4 is characterized in that the photocatalyst paint according to any one of claims 1 to 3 is a steel plate coated with a thickness of 5 μm or more.

  According to the invention which concerns on Claim 4 which has said structure, since the hardened coating film has a softness | flexibility, it can be set as the steel plate which can be bent after coating. In addition, since the photocatalyst coating having a thickness of 5 μm or more is applied, a coating film that can sufficiently exhibit the stain resistance function, the deodorizing function, and the antibacterial function can be formed.

  The invention according to claim 5 is a tent place to which the photocatalyst paint according to any one of claims 1 to 3 is applied to a thickness of 5 μm or more.

  According to the invention which concerns on Claim 5 which has said structure, it is set as the tent place provided with the coating film which exhibits a predetermined photocatalytic function, using the photocatalyst coating material which can be apply | coated also to the tent place which repeats folding and an assembly. Can do.

  As described above, according to the present invention, not only is it not deteriorated by the photocatalytic function, but also the coating film after drying and curing has flexibility and super hydrophilicity, and is very effective against environmental pollution. It can be set as a simple photocatalytic coating. Furthermore, it has a coating film that does not peel off even if the substrate coated with the photocatalyst paint is bent, and it is possible to obtain a steel plate that can be bent after coating and a tent place that can be repeatedly folded and assembled.

  Hereinafter, embodiments of the photocatalyst coating material according to the present invention will be described in detail.

  The photocatalyst coating material according to the present invention is a coating material in which a photocatalytic metal oxide is blended using Nafion (registered trademark of DuPont), which is polytetrafluoroethylene in which sulfonic acid groups are graft-polymerized, as a resin binder.

  The Nafion (registered trademark of DuPont) is an organic polymer that is generally used as a solid electrolyte of a polymer solid fuel cell, and is a resin that is highly stable to electrochemical reactions.

  For this reason, the present inventor has confirmed that the photocatalytic reaction, which is a kind of electrochemical reaction, is very stable.

  As the metal oxide having a photocatalytic function, titanium oxide, zinc oxide, tin oxide, and the like are present. In particular, titanium oxide that has a stable photocatalytic function and is easily available is preferably used. The titanium oxide is in the form of fine particles, and a predetermined amount of the titanium oxide is mixed in an appropriate resin binder, an organic solvent, water, and the like, and stirred to produce a predetermined photocatalyst paint.

  In general, as a resin binder that disperses photocatalytic metal oxides such as titanium oxide, in order to promote the reaction of the photocatalyst, and to clean the coating surface by utilizing superhydrophilicity, which is one of the photocatalytic properties. In addition, a hydrophilic resin binder is employed.

  However, when a photocatalytic metal oxide is blended with a hydrophilic resin binder, there is a problem that durability is shortened because binder decomposition (self-collapse of the binder) occurs due to an intense redox reaction due to photocatalytic action.

  Therefore, a glassy inorganic binder called silica sol is currently used. Since this silica sol exhibits almost the same properties as glass, it is stable to photocatalysis but has no flexibility and has two fatal defects that require a long time for the curing reaction.

  And since there is no softness | flexibility, if the member once painted is bent, a crack will generate | occur | produce in a coating film or peeling will arise. In addition, since the curing reaction takes a long time, it is unsuitable for high-speed continuous production of colored steel sheets.

  However, the present inventor uses the above-mentioned Nafion (registered trademark of DuPont), which is an organic polymer generally used as a solid electrolyte of a polymer solid fuel cell, as a binder, and uses titanium oxide, which is a photocatalytic metal oxide, as a binder. When the blended composition was generated, it was revealed that the binder constituting the composition exhibits hydrophilicity but does not deteriorate without receiving a photocatalytic action.

  Moreover, it became clear that the coating material produced | generated by mix | blending a solvent (for example, ethanol) with said composition was very short in the drying time after coating.

  Therefore, the photocatalyst paint obtained by mixing a predetermined amount of Nafion (registered trademark of DuPont), titanium oxide and a suitable solvent such as ethanol and water and mixing them, exhibits the conventional photocatalytic function and super hydrophilicity. In addition, the resin binder does not deteriorate and the paint has a short drying time.

  It was also revealed that the photocatalyst paint using Nafion (registered trademark of DuPont) as a binder has a very flexible coating film.

  Therefore, the coating material is also suitable for high-speed continuous production of coated products, and can be applied to a color steel plate that is bent after coating. Furthermore, it has been found that the photocatalyst paint can be applied to tents that are repeatedly folded and assembled.

  Further, since the binder does not self-destruct, the binder does not deteriorate even if the blending amount of the photocatalytic metal oxide to be blended is increased. Therefore, it is possible to increase the concentration of the metal oxide to the extent that it can be applied as a paint.

  If it is a coating material containing a photocatalytic metal oxide, it exhibits super hydrophilicity and is less susceptible to environmental pollution. Furthermore, it is also possible to exert other deodorizing functions and antibacterial functions, which are other photocatalytic functions.

  In order to sufficiently exhibit the deodorizing function and antibacterial function described above, the coating film itself needs to have a sufficient gas adsorption capacity. To that end, the adsorption surface area of the coating film may be increased. Further, in order to increase the adsorption surface area of the coating film, a metal oxide such as titanium oxide blended in the coating material having a large specific surface area may be employed. For example, porous titanium oxide manufactured by Ishihara Sangyo Co., Ltd. ST-01 can be used.

  Furthermore, by setting it as the coating film more than predetermined thickness (for example, 5 micrometers or more), an adsorption | suction function can be carry | supported not only on the apply | coated surface but the inside of the coating film thickness direction. For this reason, the deodorizing function can be sufficiently exerted even on the gas or liquid adsorbed inside.

  Next, a specific example of a photocatalyst paint will be described.

Example A: Titanium oxide ST-01 (manufactured by Ishihara Sangyo Co., Ltd .: adsorption surface area of 300 m ² / g), 50 parts by weight of Nafion DE2021 (DuPont product 20% solution) and 40 parts by weight of ethanol were blended. A photocatalyst coating material according to the present invention prepared in the above manner.

  Comparative Example B: Photocatalyst paint using Snowtex 20 (manufactured by Nissan Chemical Industries, Ltd.), which is a hydrophilic polymer, instead of Nafion DE2021, and water instead of ethanol.

Using Example A and Comparative Example B, using a PET film as a base material and applying 50 g / m ^{2 of} photocatalyst paint on the surface, curing time, presence or absence of photocatalytic effect, and bending Table 1 shows the results of examining the state of the coating film. The photocatalytic effect was confirmed by the antifouling effect and the deodorizing effect.

  The antifouling effect was visually inspected for the contamination state of the photocatalyst construction part and the non-construction part by natural exposure outdoors for two months. Further, in the deodorization experiment, measurement was performed by changing the concentration of ammonia 3 hours after irradiation with a 20 W fluorescent lamp from a distance of 50 cm.

表１から明らかなように、本発明に係わる実施例Ａは、光触媒効果（防汚染効果と消臭効果）を有し、折り曲げても剥離が生じず良好な接着性を保ち、さらに乾燥硬化時間も１分と短時間でよいことが明らかとなった。また、通常の親水性ポリマーをバインダとした光触媒塗料（比較例Ｂ）では、光触媒効果は有しているが、乾燥硬化後に折り曲げると剥離が生じた。また、塗装後の乾燥硬化時間も４０分と長時間必要であった。

As is apparent from Table 1, Example A according to the present invention has a photocatalytic effect (antifouling effect and deodorizing effect), does not cause peeling even when folded, and maintains good adhesion, and further has a drying and curing time. It was revealed that a short time of 1 minute was sufficient. In addition, the photocatalyst paint (Comparative Example B) using a normal hydrophilic polymer as a binder has a photocatalytic effect, but peeling occurred when it was bent after drying and curing. Also, the drying and curing time after coating required 40 minutes.

  In other words, photocatalyst paints containing titanium oxide, which is a metal oxide, using Nafion (registered trademark of DuPont), which is a polytetrafluoroethylene graft-polymerized with sulfonic acid groups, as a binder, have antifouling function and anti-fouling properties. It not only has a predetermined photocatalytic effect by exerting a photocatalytic function such as an odor function, but the drying and curing time after coating may be very short, the applied coating film has flexibility, and the substrate is bent. However, it was found that the coating film had an effect of not peeling off.

  The reason is that the bond energy of the C—F bond constituting the fluororesin is large, and a very dense and stable molecular chain is formed. Therefore, the crystallinity is high, and the chemical resistance and weather resistance are high. It is highly stable to electrochemical reactions, and further, due to the small atomic radius and low polarizability of F atoms, intermolecular cohesion is reduced, and the properties of low surface tension and low coefficient of friction are not shown. It is thought that it becomes easy to be deformed by the force from. (Refer to page 306 of Encyclopedia of Plastics / Functional Polymer Materials: Issued by Industry Research Association Encyclopedia Publishing Center (2004)).

  As described above, the photocatalyst coating material according to the present invention is obtained by blending a metal oxide (for example, titanium oxide) having a photocatalytic function into an organic resin binder that is not decomposed by the photocatalytic function and has flexibility after drying.

  Therefore, what has the above-mentioned property (it does not deteriorate by a photocatalytic action and a coat has flexibility) should just be used as a resin binder. However, a normal resin binder is decomposed by photocatalysis because of the bond C—H bond between carbon and hydrogen, and therefore does not have a C—H bond, and has a large bond energy as described above. It is preferable to use Nafion (registered trademark of DuPont) having -F bond.

  The chemical formula of Nafion (registered trademark of DuPont) is shown below.

上記の化学式で表されるように、前記ナフィオン（Ｎａｆｉｏｎ：デュポン社の登録商標）は、パーフルオロスルホン酸を側鎖に有する高分子４フッ化エチレンの繰り返し単位からなるグラフトポリマー（スルホン酸基がグラフト重合されたポリ４フッ化エチレン）であり、Ｃ−Ｈ結合は有しておらず、電気化学反応に対して高度に安定なＣ−Ｆ結合であるので、光触媒作用を受け難い構造であるといえる。

As represented by the above chemical formula, the Nafion (registered trademark of Dupont) is a graft polymer (a sulfonic acid group having a sulfonic acid group having a repeating unit of a high molecular weight tetrafluoroethylene having perfluorosulfonic acid in a side chain. Graft-polymerized poly (tetrafluoroethylene), which has no C—H bond and is a highly stable C—F bond with respect to an electrochemical reaction, and is therefore not susceptible to photocatalysis. It can be said.

  As described above, the photocatalyst coating material according to the present invention (Example A) is a titanium oxide which is a metal oxide having a photocatalytic function by using an organic resin binder which is not easily decomposed due to photocatalysis and has flexibility after drying. Thus, the coating film after coating does not deteriorate and has a long life, and can exhibit a photocatalytic function for a long time. Moreover, since it has flexibility after drying, a photocatalyst coating material that can maintain a stable coating film state can be obtained without peeling off the coating film even if it is bent after coating.

  For this reason, it has been found that the present invention can be applied to a surface treatment material for a colored steel plate that is bent after coating, and a surface treatment material for a tent that is repeatedly folded and assembled.

  Furthermore, by using porous titanium oxide and making it a coating film with a predetermined thickness or more (according to a deodorization experiment, 5 μm or more), the gas adsorption ability is enhanced, and the photocatalyst has a deodorizing function and an antibacterial function against outside air The activity can be improved.

  In addition to colored steel plates and tents, of course, it can be used as a paint to prevent contamination of exterior walls, gate pillars, lockers, etc., and also to prevent and deodorize automobile bodies and glass surfaces. Is possible.

  It can also be used as a surface treatment material for antifouling and deodorizing effects on interior equipment such as a sofa in a vehicle.

  As described above, according to the present invention, not only is it not deteriorated by the photocatalytic action, but also the coating film after drying and curing has flexibility and also exhibits super hydrophilicity, which is extremely resistant to environmental pollution. A photocatalyst paint having an effective antifouling effect and having a long life can be obtained. Furthermore, since the drying and curing time can be very short, it can also be applied to a color steel plate production line that is continuously produced while performing high-speed baking.

  Moreover, the photocatalyst coating material which can be apply | coated also to the thin plate steel plate which performs a bending process after coating, the tent place which repeats folding and an assembly, etc. can be obtained.

  Therefore, it is possible to obtain a foldable steel sheet or tent that has a contamination prevention function and a deodorization function and is coated with a long-life coating film.

Claims (5)

  A metal oxide having a photocatalytic function is blended in an organic resin binder that has a molecular chain with a large binding energy and is not decomposed by photocatalysis, and has low intermolecular cohesive force and flexibility after drying and curing. Photocatalyst paint.   The photocatalyst coating material according to claim 1, wherein the resin binder is Nafion (registered trademark), which is polytetrafluoroethylene in which a sulfonic acid group is graft-polymerized.   The photocatalyst coating material according to claim 1 or 2, wherein the metal oxide is porous titanium oxide.   A steel plate, wherein the photocatalyst paint according to any one of claims 1 to 3 is applied to a thickness of 5 µm or more. A tent place, wherein the photocatalyst paint according to any one of claims 1 to 3 is applied to a thickness of 5 µm or more.