JP2009185107A - Hydrophilic coating material and hydrophilic coated object - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve adhesion respecting the hydrophilic coating material to dissolve the problem: although, of methods to develop antifouling effect or antistatic effect by imparting hydrophilicity to the surface of a substrate, the method of forming the film by coating a hydrophilic coating material consisting mainly of a tetrafluoroethylene resin graft-polymerized with sulfonic acid (hereinafter referred to as "Nafion" (R)) is one of the most effective, the method poses the problem of lack of adhesion to plastics and metal substrates. <P>SOLUTION: In the hydrophilic coating material containing the tetrafluoroethylene resin having graft-polymerized sulfonic acid, by mixing a heat-curable fluororesin and a curing component or mixing an acrylic silicone resin in a specific ratio and by conducting heat curing, the adhesion jumpingly improves. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a hydrophilic paint containing a tetrafluoroethylene resin grafted with sulfonic acid (hereinafter also referred to as “Nafion (registered trademark of US DuPont)”). The present invention relates to a hydrophilic paint having improved adhesion to a manufacturing material (base material) and a hydrophilic coated body in which the hydrophilic paint is applied to the surface of the base material.

  One of the methods to impart hydrophilicity to the surface of various base materials such as siding, and to produce anti-contamination effect and anti-static effect, mainly consists of tetrafluoroethylene resin (Nafion) grafted with sulfonic acid. There is a method of applying a hydrophilic paint. The coated body in which the hydrophilic coating is formed on the surface of the base material by this method has either a static contact angle or a dynamic receding contact angle of 30 ° or less in a non-photoexcited state (a state where no light is irradiated). It exhibits a hydrophilic action.

On the other hand, the method using a so-called known photocatalyst (metal oxide such as titanium oxide) has the following problems. That is,
1. Since a back reaction occurs, prior to the application of the clear containing the photocatalyst, a barrier coat to protect the base from the back reaction must be further applied, and equipment for the additional process must be newly installed.

2. Since hydrophilicity is manifested only by light irradiation, it is difficult to carry out a hydrophilic shipping inspection at the time of manufacture and shipment.
JP-A-9-227805

However, in the case of a hydrophilic paint mainly composed of Nafion (registered trademark), there are problems to be solved as follows. That is,
Nafion (registered trademark) is originally a fluororesin and does not have adhesiveness, and the sulfonic acid group contained in the polymer structure is a negative ion and tends to attract positive ions, so plastic materials, metal materials, etc. It adheres to a certain extent to the base material by the suction force between the weak ions. However, there was not enough adhesiveness to exhibit wear resistance.

  The present invention has been made in view of the above-described points, and overcomes the weakness of the hydrophilic coating mainly composed of Nafion (registered trademark) to improve the adhesiveness, thereby improving the adhesiveness. Applying to the surface of a substrate with a smooth surface, etc., and forming a film, it is possible to impart hydrophilicity to express antifouling and antistatic effects and to exhibit excellent wear resistance. It is intended to provide a hydrophilic coated body using the same paint.

  In order to achieve the above object, the hydrophilic paint according to the present invention (Claim 1) is a hydrophilic paint containing a tetrafluoroethylene resin (Nafion (registered trademark)) obtained by graft polymerization of sulfonic acid. A curable fluororesin and its curing agent are contained in a range of 20 to 85% by mass in the resin component.

  According to the hydrophilic paint having the above-described configuration, the content of the resin component of the thermosetting fluororesin and its curing agent (curing agent resin) is 20 mass of the total resin component (including the resin component in Nafion). When less than%, sufficient adhesion to the substrate cannot be secured, while when it exceeds 85% by mass of the total resin component, it is represented by the hydrophilicity of Nafion (registered trademark), which is the main component of the hydrophilic paint, This is because the so-called photocatalytic effect is not effectively exhibited. And the extremely low adhesive force of Nafion is supplemented by containing the resin component of the thermosetting fluororesin and its curing agent in the range of 20 to 85% by mass in the total resin components as described above.

  In other words, Nafion has only a sulfonic acid reactive functional group, but sulfonic acid has a property that it is difficult to form a covalent bond because of its strong ionicity. By taking advantage of this property and coexisting with a thermosetting fluororesin, which is a resin component that is compatible with Nafion and easily binds to the surface of the substrate, and its curing agent, the adhesive force is greatly improved, workability and Abrasion resistance is also improved. As a result, hydrophilicity is imparted to the surface of the base material in a non-photoexcited state, and an anti-contamination effect or an anti-static effect is exhibited. In addition, since the compounding ratio of the curing agent with respect to the thermosetting fluororesin varies depending on the type of the curing agent (resin for use), it is not limited, but usually 5 to 40 weights per 100 parts by weight (mass) of the thermosetting fluororesin ( Mass) part.

  In order to achieve the above object, the hydrophilic paint according to the present invention (Claim 2) is a hydrophilic paint containing a tetrafluoroethylene resin obtained by graft polymerization of sulfonic acid, wherein the acrylic silicone resin is contained in the resin component. It is contained in the range of 20 to 70% by mass.

  According to the hydrophilic paint having the above structure, when the content of the acrylic silicone resin is less than 20% by mass of the total resin components (including the resin component in Nafion), sufficient adhesion to the substrate cannot be ensured. On the other hand, if it exceeds 70% by mass of the total resin components, the so-called photocatalytic effect represented by the hydrophilicity of Nafion (registered trademark), which is the main component of the hydrophilic paint, cannot be effectively exhibited. And the extremely low adhesive force of Nafion is supplemented by containing acrylic silicon resin in the range of 20-70 mass% in all the resin components as mentioned above. In addition, taking advantage of the property that Nafion's sulfonic acid covalent bond is difficult to form, and by coexisting with an acrylic silicon resin that is compatible with Nafion and easily binds to the surface of the substrate, adhesion is greatly improved. To improve the workability and wear resistance. As a result, hydrophilicity is imparted to the surface of the base material in a non-photoexcited state, and an anti-contamination effect or an anti-static effect is exhibited.

  As described in claim 3, the thermosetting fluororesin curing agent in the hydrophilic paint according to claim 1 is any one of (block) isocyanate, melamine resin, polyamide, acid anhydride, and silane coupling agent. It is preferable that it is a mixture of 1 to 5 types selected.

  Thus, the thermosetting fluororesin forms a film only after inducing a crosslinking reaction by a curing agent, which simultaneously means improvement of film strength and base adhesion. The curing agents listed in the claims are most suitable for obtaining the maximum effect.

  As described in claim 4, a photocatalyst can be included in the pigment component of the hydrophilic paint.

  By comprising in this way, in the hydrophilic coating material of any one of Claims 1-3, there exists a photocatalytic effect, such as deodorizing, antibacterial, and air purification, without decomposing | disassembling Nafion. Further, the photocatalyst as a pigment component is any one of 1 to 4 types selected from titania sol, titanium oxide surface-coated with zeolite, titanium oxide surface-coated with silica, and titanium oxide surface-coated with apatite. It is preferable to use one or a mixture of two or more.

  The hydrophilic coated body according to claim 5 is a surface of the substrate by applying the hydrophilic paint according to any one of claims 1 to 4 to the substrate surface and heating at a temperature of 80 to 200 ° C. It is characterized by being formed into a film.

  According to the hydrophilic coated body having the above-described configuration, since the heat resistant temperature of the vinyl chloride resin is around 80 ° C., it should be heated and baked at 80 ° C. or higher, while Nafion and thermosetting fluororesin are 200 ° C. Is the upper limit temperature. More specifically, the coated body in which the hydrophilic paint according to the present invention is applied to the surface of the base material is placed in an oven having an atmospheric temperature of 80 ° C. to 200 ° C. and baked for 5 to 30 minutes, or a conveyor for transporting the coated body is used. It can be baked for 1 to 3 minutes in a high velocity oven equipped with a hot air discharge temperature of 80 ° C. to 200 ° C. and a high wind speed.

  The hydrophilic paint having the above structure and the hydrophilic coated body using the paint have the following excellent effects.

  Nafion (registered trademark) is a hydrophilic polymer, and unlike conventional photocatalytic paints, it does not receive light, that is, exhibits hydrophilicity in a non-photoexcited state, and also exhibits anti-contamination and antistatic effects. As described above, since the adhesiveness is low, even if a coating film is formed when applied to a substrate having a smooth surface such as a plastic material or a metal material, it is easily peeled off, so that the implementation is difficult. On the other hand, according to the hydrophilic paint of the present invention, the contained Nafion has only a reactive functional group having a sulfonic acid, and the sulfonic acid has a strong ionicity and is difficult to form a covalent bond. By making use of it, coexistence of the thermosetting fluororesin and its curing agent resin or acrylic silicon resin, which is compatible with Nafion and easily binds to the surface of the base material, the adhesion of Nafion is low. Can be adequately compensated. In addition, by improving the adhesive strength of the hydrophilic paint, it is possible to simultaneously improve the workability and friction resistance of the coated body to which the hydrophilic paint of the present invention is applied.

  Hereinafter, embodiments of the hydrophilic paint of the present invention will be described.

Example 1
A thermosetting fluororesin and its curing agent are used as resin components.

a) Thermosetting fluororesin (trade name “Fluonate K702” manufactured by Dainippon Ink and Chemicals, Inc.) 20
b) Melamine resin for curing agent (trade name “Super Becamine L105-60” manufactured by Dainippon Ink and Chemicals, Inc.)
c) Nafion (registered trademark) solution (trade name “Nafion DE2020” manufactured by DuPont, USA) 50
d) N-butyl acetate 25
Since the non-volatile content of a) is 50% by mass and the non-volatile content of b) is 60% by mass, the cross-linked fluororesin in which a) and b) are combined and its curing agent component is 13 parts by mass. In addition, since the non-volatile content of c) is 20% by mass, the content of the crosslinkable fluororesin and its curing agent component in the paint resin component is 56.5% by mass.

This solution (hydrophilic paint) was applied to a polyester resin baked paint plate by spraying. The coating amount was 100 g / m ^2, and it was baked in an atmosphere of 140 ° C. for 10 minutes (heated at a temperature of 140 ° C. for 10 minutes).

Comparative Example 1
Example 1 c) A sample was prepared in the same manner as in Example 1 except that the amount of Nafion solution was 10, and the content of the cross-linked fluororesin and the curing agent component in the coating resin component was 86.7% by mass. did.

Example 2
Acrylic silicon resin is used as a resin component.

  A paint was prepared according to the following formulation.

a) Acrylic silicone resin (product of Showa Polymer "Polysol AP3900") 40
b) Ethylene glycol 10
c) Nafion solution (Nafion DE2020, a product manufactured by DuPont, USA) 30
d) Water 20
Since the non-volatile content of a) is 50% by mass and the non-volatile content of c) is 20% by mass, the content of the acrylic silicon resin in the paint resin component is 77% by mass.

This solution was applied to a PVC plate by spraying. The coating amount was 100 g / m ^2, and it was dried in an atmosphere at 80 ° C. for 10 minutes.

Comparative Example 2
Example 2 is the same as Example 2 except that the content of the acrylic silicon resin in the paint resin component is 18.2% by mass by setting a) the acrylic silicon resin to 8 and c) the Nafion solution to 90. A sample was prepared.

Example 3
(This is an example using a silane coupling agent as the curing agent)
a) Thermosetting fluororesin (trade name “Fluonate K702” manufactured by Dainippon Ink and Chemicals, Inc.) 30
b) Isocyanate-based silane coupling agents (Momentive Performance Chemicals)
(Product name “Y-5187” manufactured by Japan) 3
c) Nafion (registered trademark) solution (trade name “Nafion DE2020” manufactured by DuPont, USA)
d) N-butyl acetate 26
e) Curing accelerating catalyst "dibutyltin diacetate 0.1% solution" 1

Since the non-volatile content of a) is 50% by mass and the non-volatile content of b) is approximately 100% by mass, the total amount of the cross-linked fluororesin and the curing agent component of a) and b) is 18 parts by mass. Further, since the non-volatile content of c) is 20% by mass, the content of the cross-linked fluororesin and the curing agent component in the paint resin component is 64.3% by mass.

This solution (hydrophilic paint) was applied to a polyester resin baked paint plate by spraying. The coating amount was 100 g / m ^2, and it was baked in an atmosphere of 140 ° C. for 10 minutes (heated at a temperature of 140 ° C. for 10 minutes).

In addition to the silane coupling agent, it goes without saying that (block) isocyanate, melamine resin, polyamide, and acid anhydride can be used, and two kinds selected from the above-mentioned curing agents including the silane coupling agent are used. Five mixtures can also be used.

Example 4
(This is an example containing a photocatalyst)
A thermosetting fluororesin and its curing agent are used as resin components.

a) Thermosetting fluororesin (trade name “Fluonate K702” manufactured by Dainippon Ink and Chemicals, Inc.) 20
b) Melamine resin for curing agent (trade name “Super Becamine L105-60” manufactured by Dainippon Ink and Chemicals, Inc.)
c) Nafion (registered trademark) solution (trade name “Nafion DE2020” manufactured by DuPont, USA) 50
d) N-butyl acetate 10
e) Photocatalytic titanium oxide slurry (product of Ishihara Sangyo Co., Ltd.) “STS-100” 15
Since the non-volatile content of a) is 50% by mass and the non-volatile content of b) is 60% by mass, the cross-linked fluororesin in which a) and b) are combined and its curing agent component is 13 parts by mass. Further, since the non-volatile content of c) is 20% by mass, the content of the crosslinkable fluororesin and its curing agent component in the paint resin component is 56.5% by mass. Moreover, since the non-volatile content of STS-100 is 20 mass%, the photocatalyst density | concentration which occupies for the whole non-volatile content will be 11.5 mass%.

This solution (hydrophilic paint) was applied to a polyester resin baked paint plate by spraying. The coating amount was 100 g / m ^2, and it was baked in an atmosphere of 140 ° C. for 10 minutes (heated at a temperature of 140 ° C. for 10 minutes).
Table 1 below shows the comparative performance test results.

・接着性
碁盤目テープ剥離試験：碁盤目セロテープ（登録商標）剥離で100/100の良好な接着性を確認して「○」と判定した。逆にチョーキングあるいは塗膜の白濁があり、その面での碁盤目セロテープ（登録商標）剥離が100/100より悪い場合を「×」と判定した。
・親水性
動的・後退接触角を測定した。動的・後退接触角：３０°以下を○、８０°以上を×とした。手順としては、まず水平に静置した試料表面に水滴を２μｌ滴下し、１分経過後に更に４μｌ滴下して追加した。１分経過後にその追加分の４μｌを吸引して、更に１分経過後にその界面の接触角を測定した。
・加工性
基材を１８０°折り曲げてそのときのクラック発生をルーペで確認。クラック発生なしを○、クラックが発生したものを×とした。
・耐摩擦性
テーバー磨耗試験。荷重１ｋｇで２００回転時の減量が２ｍｇ以下であれば○とし、同条件下での減量が２ｍｇを超える場合には×とする。
・上記各実施例または各比較例の塗料を塗布した基材の種類
実施例１、実施例３、実施例４および比較例１はポリエステル塗装鋼板（高温で焼付け 可能）、実施例２、比較例２は塩ビ板（低温乾燥のみ可能）である。
・メチレンブルー分解活性
この分媒活性はＪＩＳ Ｒ １７０３−２に定義されている。消臭・抗菌・大気浄化等の光触媒効果を再現性のある数値として表記しうる代表的な尺度が、メチレンブルーを用いた分解活性指数であるが、このメチレンブルーは光照射による劣化が極めて少なく、逆にラジカル（遊離基）と選択的に反応するため、光触媒反応でラジカルが生じると急速に脱色するという特性を有している。光触媒反応の効果と目される消臭・抗菌・大気浄化作用は、すべて発生するラジカルにより惹起されるものであるから、メチレンブルーの分解とこれらの効果の間には密接な相関関係が存在する。

-Adhesive cross-cut tape peeling test: 100/100 good adhesiveness was confirmed by cross-cut cello tape (registered trademark) peel, and judged as "O". On the other hand, a case where there was choking or cloudiness of the coating film, and the peeling of the cellar cellotape (registered trademark) on that surface was worse than 100/100, was judged as “x”.
・ Hydrophilicity Dynamic and receding contact angles were measured. Dynamic and receding contact angle: O for 30 ° or less and x for 80 ° or more. As a procedure, first, 2 μl of water droplets were dropped on the surface of a sample that was allowed to stand horizontally, and 4 μl was further dropped after 1 minute. After 1 minute, 4 μl of the additional amount was sucked, and after another 1 minute, the contact angle of the interface was measured.
・ Machinability Bending the substrate 180 ° and confirming the occurrence of cracks with a loupe. The case where no crack was generated was indicated as “◯”, and the case where a crack occurred was indicated as “X”.
・ Abrasion resistance Taber abrasion test. If the weight loss at 200 revolutions is 2 mg or less with a load of 1 kg, it is marked as ◯, and if the weight loss under the same condition exceeds 2 mg, it is marked as x.
-Types of base materials to which the paints of the above examples or comparative examples are applied Examples 1, 3, 4, and 1 are polyester-coated steel sheets (can be baked at high temperatures), Example 2, and Comparative Examples 2 is a vinyl chloride plate (only low temperature drying is possible).
-Methylene blue decomposition activity This solvent separation activity is defined in JIS R 1703-2. A representative measure that can be used to express photocatalytic effects such as deodorization, antibacterial activity, and air purification as a reproducible value is the degradation activity index using methylene blue. Since it reacts selectively with radicals (free radicals), it has the property of rapidly decoloring when radicals are generated by photocatalytic reactions. Since the deodorizing, antibacterial, and air purification effects that are considered to be the effects of the photocatalytic reaction are all caused by radicals generated, there is a close correlation between the decomposition of methylene blue and these effects.

Claims (5)

  In a hydrophilic paint containing a tetrafluoroethylene resin graft-polymerized with sulfonic acid, a thermosetting fluororesin and its curing agent are contained in a range of 20 to 85% by mass in the resin component. Hydrophilic paint.   A hydrophilic paint containing a tetrafluoroethylene resin graft-polymerized with sulfonic acid, wherein an acrylic silicon resin is contained in a range of 20 to 70% by mass in the resin component.   The curing agent of the thermosetting fluororesin is a mixture of 1 to 5 types selected from any of (block) isocyanate, melamine resin, polyamide, acid anhydride, and silane coupling agent. Item 1. The hydrophilic paint according to Item 1.   The hydrophilic paint according to any one of claims 1 to 3, wherein the pigment component of the hydrophilic paint contains a photocatalyst.   The hydrophilic paint according to any one of claims 1 to 4 is applied to a surface of a substrate, and the film is formed on the surface of the substrate by heating at a temperature of 80 to 200 ° C. Item 5. A hydrophilic coated body in which the hydrophilic paint according to any one of Items 1 to 4 is coated on a surface.