JP2002036442A - Highly durable coating film structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new highly durable coating film structure capable of effectively suppressing a photodegradation or the like for a long period and providing excellent durability at a relatively low cost. SOLUTION: The highly durable coating film structure comprises an organic coating film executed on a base and a finishing coating film executed on an uppermost layer so that the uppermost finishing coating film is formed as a transparent silicone resin film containing an inorganic ultraviolet absorber.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a highly durable coating film structure. More specifically, the invention of this application relates to a high-durability coating composition that is useful as a roof tile, an outer wall material, an interior material, or the like, and is inexpensive and has excellent durability.

[0002]

2. Description of the Related Art Conventionally, in the case of building materials such as roof tiles, exterior materials, and interior materials, painted products in which a paint is applied to the surface of a ceramic base material such as cement, a resin base material, or a metal base material. Has been widely used. Usually, in these coated articles, organic paints as solutions or emulsions are used as paints.

Further, in recent years, organic paints have been unable to provide sufficient performance in terms of weather resistance and corrosion resistance due to deterioration due to light, rainwater, and the like, and are therefore coated using inorganic coating agents. Therefore, such an inorganic coating agent has already been put into practical use.

[0004]

However, in the case of the conventional inorganic coating agent, although the material itself has relatively good weather resistance and corrosion resistance, it is used for 10 years to 1 year.
In the long term of 5 years, the coating deteriorates,
Causes chalking and eventually discolors.

[0005] In the case of externally related products such as exterior materials, exteriors, rain gutters and the like, the durability performance required for the members is on the level of 30 years.

In the case of an inorganic coating agent,
Since it is more expensive than organic paints that have been used widely in the past, it has been a major problem to reduce the amount of use.

[0007] Under these circumstances, in order to extend the life of the coating film by adding a general UV absorber or a light stabilizer to the inorganic coating agent, and to reduce the amount of the inorganic coating agent, the inorganic coating agent is used. It has been studied to arrange a general organic film having a poor light degradation resistance or the like as a coating film using the agent only as the uppermost layer and a lower layer. In other words, by using an inorganic coating agent only for the uppermost layer to make the structure relatively inexpensive, and by adding an ultraviolet absorber to the inorganic coating agent, the coating film itself with the inorganic coating agent, Another object of the present invention is to improve the durability by suppressing the deterioration of the underlying organic film. However, when organic substances are used as UV absorbers or light stabilizers, these substances gradually escape from the coating surface, causing bleed-out or deterioration of these organic UV absorbers themselves. The problem of losing efficacy was inevitable.

Although the use of an inorganic UV absorber in place of an organic UV absorber has been considered, it is difficult to uniformly disperse it in the whole coating film and it is not easy to suppress color change. For example, there is a problem that weather resistance and durability are not always practically sufficient.

Therefore, the invention of this application solves the conventional problems as described above, and is capable of effectively suppressing photodeterioration and the like for a long period of time, having excellent durability and being relatively inexpensive. It is an object of the present invention to provide a new highly durable coating composition that can be used.

[0010]

Means for Solving the Problems The present invention solves the above-mentioned problems. First, an organic coating film is applied to a substrate, and a top coating film is applied to the uppermost layer. A highly durable coating composition, which is a film composition, wherein the uppermost top coating film is formed as a transparent silicone resin film containing an inorganic ultraviolet absorber.

Further, the invention of this application is characterized in that, secondly, the transparent silicone resin film is formed of one of a silicone resin comprising a polymer of a hydrolyzable organosilane and a silicone resin which is a modified product thereof. The above-mentioned highly durable coating composition is provided as a coating of one or more kinds of compositions. Thirdly, the modified silicone resin is an acrylic-modified silicone. High durability coating composition characterized in that it is at least one member selected from the group consisting of epoxy resin, epoxy-modified silicone resin, polyester-modified silicone resin, alkyd-modified silicone resin and phenol-modified silicone resin. Provide body.

Fourth, the invention of this application relates to any one of the above inventions. Fourth, the inorganic ultraviolet absorber is a fine particle having a primary particle size of 0.01 to 0.5 μm. Fifth, a silicone resin composition for forming a transparent silicone resin film is provided as a weight ratio to the solid content of the composition, A highly durable coating composition comprising 1-30% of an inorganic ultraviolet absorber fine particle, and sixthly, a silicone-based coating composition for forming a transparent silicone-based resin film. The resin composition is obtained by mixing a paste obtained by adding inorganic ultraviolet absorbent fine particles to a hydrolyzable organosilane or a silica-dispersed oligomer prepared by hydrolyzing the same to a silicone resin. Endurance Sex coating structure, the seventh, inorganic ultraviolet absorbers, provides high durability coating structure, which is a zinc oxide.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The invention of this application has the features as described above, and embodiments thereof will be described below.

[0014] The invention of this application is to form a low-durability transparent, that is, a clear silicone resin film on the uppermost layer, and to use an inorganic ultraviolet absorber contained therein to form an inexpensive underlayer organic coating film. Is protected from ultraviolet rays and has a long-term durability. In this case, the transparent silicone resin film is preferably exemplified by one or more of a silicone resin composed of a polymer of a hydrolyzable organosilane and a silicone resin which is a modified product thereof. Can be constituted as a coating film of the composition of the above.

The hydrolyzable organosilane is, for example,
Six_Four, RSix_Three, R_TwoSix _Two, R_ThreeSix
_Two(X in the formula is a chlorine atom or OR¹And R is
The same or different, a hydrocarbon group such as an alkyl group,
An alkenyl group or an aryl group;¹Is carbonized
That a hydrogen group or a part thereof may be a hydrogen atom
May be selected from various types represented by K
Rear (transparency) silicone resin is
Silane or chloroalkoxysilane or alkoxy
Solvent-free or using multiple silanes
Is prepared by hydrolysis and polymerization in an organic solvent.
It is. Usually, these hydrolyzable organosilanes are
Trifunctional or bifunctional ones are more preferably used. So
In the general formula, the organic groups R, R¹A typical example of
Examples include a methyl group, an ethyl group, and a phenyl group.

Although the prepared silicone resin is difficult to express as a clear chemical structure, for example, the following repeating structure can be considered.

[0017]

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The curing of such a silicone resin is most commonly caused by heat or a catalyst by means of a functional silanol group (Si-OH) or an alkoxy group (Si-OR).
¹ ) is considered as forming a siloxane bond by condensation reaction by dehydration or dealcoholization.

In the invention of this application, a modified silicone resin is exemplified as a suitable silicone resin constituting the transparent silicone resin film. As the modified silicone resin, epoxy-modified, polyester-modified, alkyd-modified, and phenol-modified silicone-based resins are exemplified by acrylic silicone (acryl-modified).

The modification in this case can be carried out by various methods, but a condensation reaction and an addition reaction are typical. In the case of the condensation reaction, the alcoholic hydroxyl group of the organic resin and the functional group (silanol group or alkoxy group) of the silicone resin are heated without a catalyst or in the presence of a catalyst such as an organic titanate, and are condensed by a dehydration reaction or a dealcoholization reaction.

In the case of the addition reaction, there are a method of introducing silane or siloxane by hydrosilylation to an unsaturated group-containing organic resin under a platinum catalyst, and a method of reacting a hydroxyalkyl group-containing siloxane with a melamine resin or an isocyanate compound.

A filler may be added to these transparent silicone resins at a level that does not impair its clearness. Examples of the filler include a small amount of pigment and extender pigment such as silica powder and barium sulfate. At that time, if necessary, a dispersant, a thickener, a coupling agent, and the like can be used.

An inorganic ultraviolet absorber is blended with the transparent silicone resin. The inorganic ultraviolet absorbing agent to be blended is indispensable for protecting the action by ultraviolet rays with a clear silicone-based coating.

Generally, organic UV absorbers include 2
Benzooliazole-based compounds such as (2'hydroxy-5-methylphenyl) benzotriazole and 2,4-
There is a benzophenone-based compound such as dihydroxybenzophenone, etc., which bleeds out by vibrating with the energy of ultraviolet rays and sublimates from the organic resin. In addition, a phenomenon occurs in which the ultraviolet absorber itself deteriorates and the effect is lost, and a long-term effect cannot be expected. Although it depends on the amount of addition, it usually has a life of 2 to 3 years.

On the other hand, fine particles of zinc oxide, cerium oxide, zirconium oxide, iron oxide, titanium oxide and the like are used as the inorganic ultraviolet absorber of the present invention. In the present invention, the fine particles of zinc oxide and titanium oxide are excellent in ultraviolet ray cutting ability. However, in the case of zinc oxide,
It is necessary to devise a particle size and a dispersion method in order to obtain a clear coating film. It should be noted that titanium oxide has some concealing properties.

These inorganic ultraviolet absorbers, especially fine particle zinc oxide, have a primary particle size (non-agglomerated particles) of 0.01 to 0.1 in silicone resin.
It is desirable to be blended as 5 μm. And about the compounding ratio, as a weight ratio with respect to the solid content of a silicone-type resin composition, generally, 1
It is appropriate that the amount is not less than 30% by weight and not more than 30% by weight. More preferably, the content is 5% by weight or more and 20% by weight or less.

In general, for example, when the coating amount of a silicone resin is about 10 g / m ² , it is difficult to obtain a sufficient ultraviolet ray cutting effect when the amount is less than 1% by weight, while it exceeds 30% by weight. In such a case, the transparency and gloss of the transparent silicone resin coating film tend to be lost, and the performance such as the strength is also deteriorated.

In order to uniformly disperse the particulate zinc oxide in the silicone resin, it is effective to prepare a paste of the particulate zinc oxide in advance and mix it with the silicone resin.

That is, zinc oxide can be easily dispersed in a hydrolyzable organosilane monomer represented by the general formula (R ⁰ ) _n SiX _4-n used for an organosilane silica-dispersed oligomer solution. Have excellent long-term storage stability. Therefore, it is effective to use the hydrolyzable organosilane in a paste state in which fine zinc oxide is added and dispersed. In addition to directly adding the zinc oxide fine particles to the hydrolyzable organosilane, the silica oxide dispersion solution of the organosilane prepared by partially hydrolyzing the hydrolyzable organosilane of (R ⁰ ) _n SiX _4-n is added to the silica dispersion oligomer solution of the organosilane. May be added and dispersed. A paste using a silica-dispersed oligomer solution prepared by partially hydrolyzing the hydrolyzable organosilane has better long-term stability. On the other hand, a paste using a monomer solution is advantageous in that the preparation process is short. Which system is used can be selected as needed. In the above formula, R ⁰ represents a substituted or unsubstituted monovalent hydrocarbon group having 1 to 8 carbon atoms, and X represents a hydrolyzable group. n
Is an integer of 0 to 3.

As in the invention of this application, if there is a clear silicone resin coating containing an inorganic ultraviolet absorber (for example, fine particle zinc oxide) having a semi-permanent life on the uppermost layer, the lower layer is coated. The film may be an inexpensive organic paint that does not have weather resistance, and this allows a wider range of choices of paint and coating composition.

Of course, the reason why the silicone-based clear resin is used here is that the resin itself has excellent weather resistance. Since it is necessary to fix the ultraviolet absorber for a long period of time, the uppermost layer containing the ultraviolet absorber is required to have weather resistance, and the weather resistance of the resin determines the life of the component.

According to the present invention, it is possible to enhance the weather resistance of a coated product, so that a ceramic-based exterior material, a metal-based exterior material,
It is suitable to be applied to a base material of an exterior material that is used outdoors, such as a resin-based exterior material, and that requires particularly high weather resistance.
Of course, the coating method at that time is not particularly limited.

With respect to the organic coating film which is formed as a base layer of the clear silicone resin coating film, various organic coating materials may be used for forming the organic coating film. The selection can be made in consideration of the adhesion to the clear silicone resin coating film, the coating property, the color tone, and the like. For example, use of an epoxy emulsion paint, an acrylic emulsion paint, an acrylic silicone emulsion paint, or the like is exemplified.

The thickness of the coating film of the silicone-based paint containing the inorganic ultraviolet absorber is not particularly limited.
What is necessary is just about 0.1-300 micrometers. If the coating film is thin, problems occur in adhesion and weather resistance. When the film thickness is large, the curability,
A problem occurs in paintability.

The baking is not limited, but may vary depending on the catalyst added.
Is the general baking temperature. Therefore, examples will be shown below, and the invention of this application will be described in more detail. Of course, the invention of this application is not limited by the following examples. Further, in the following, unless otherwise specified,% means parts by weight and parts means parts by weight. <Preparation of paste (C-1)> Methylmethoxysilane 5
For 0 part, 40 parts of fine particle zinc oxide having an average particle diameter of 0.04 μm, 5 parts of a carboxylic dispersant, and 5 parts of a diluting solvent were added, and the mixture was stirred and mixed with a disper for about 30 minutes. One more
Fine particle zinc oxide paste (c-1) was prepared by dispersing using mm glass beads with a dispersing machine (Dino mill manufactured by Ichimaru Enterprise) (flow rate: 25 kg / hr, vessel volume: 1.5 liters, 5 times). In the same manner, a paste (c-2) was prepared for fine-particle titanium oxide having an average particle size of 0.04 μm. <Preparation of Pastes (Z-1, Z-2, Z-3)> Fine particles of zinc oxide are added and dispersed in an oligomer solution prepared by partially hydrolyzing a hydrolyzable organosilane to prepare a paste. That is, 0.17 g of 1/1000 normal hydrochloric acid was added to 50 parts of methyltrimethoxysilane, and the mixture was allowed to stand for 2 days. Then, 40 parts of fine zinc oxide having an average particle size of 0.04 μm were added, and a carboxylic acid-based dispersant 5 was added. And 5 parts of a diluting solvent, and stirred and mixed with a disper for about 30 minutes. One more
Fine particle zinc oxide paste (Z-1) is obtained by dispersing using a glass bead with a dispersing machine (Dino mill manufactured by Ichimaru Enterprise Co., Ltd.) (flow rate: 25 kg / hr, vessel capacity: 1.5 liters, 5 times). Similarly, the amount of 1 / 1000N hydrochloric acid was 1.7 g,
7 g of the paste obtained, respectively (Z-
2) and (Z-3). (Examples 1 to 3 and Comparative Examples 1 to 3) An organic paint (types are shown in Table 1) having a film thickness of 30 μm is applied to a ceramic substrate composed of a cement-based inorganic plate preheated to 60 ° C. in advance. And then baking at 90 ° C. for 20 minutes to form an organic coating layer. Next, a fine zinc oxide paste prepared in the above (c-1) was added to a clear silicone resin as shown in Table 1 and a non-added zinc oxide paste was prepared, and then coated to a film thickness of 30 μm. do it,
Example 1 in which a particulate zinc oxide paste having a silicone-based coating film formed by baking at 120 ° C. for 20 minutes was added.
Comparative Examples 1 to 3 and Comparative Examples 1 to 3 not added. The addition amount of the fine particle zinc oxide was 10% based on the resin solid content in the paint.

For evaluation of the obtained coating film, a sunshine weatherometer test of an accelerated weather resistance test according to JIS was performed. Table 2 shows the evaluation results of the weather resistance. It can be seen that when an inorganic ultraviolet absorber (fine-particle zinc oxide) is added to the clear silicone coating of the uppermost layer, the organic layer thereunder is protected and the weather resistance is excellent.

[0037]

[Table 1]

[0038]

[Table 2]

(Examples 4 to 6, Comparative Examples 4 to 6) Example 1
To 3, and the samples shown in Table 3 were prepared and evaluated in the same manner as Comparative Examples 1 to 3.

However, fine particle titanium oxide was used instead of fine particle zinc oxide. Fine particles of titanium oxide tend to have a lower clear feeling of the coating film and become whiter. As shown in the evaluation results in Table 4, when an inorganic ultraviolet absorber (fine particle titanium oxide) was added to the clear silicone coating of the uppermost layer, the organic layer thereunder was protected and the weather resistance was excellent. You can see that.

[0041]

[Table 3]

[0042]

[Table 4]

(Examples 7 to 9, Comparative Example 7) (c-1) such that the amount of fine zinc oxide was 10% by weight based on the solid content of acrylic silicone (Neosidaka # 5000 Isaam paint). (Z-1), (z-2), (z-3)
Was added and the mixture was stirred gently to prepare a clear acrylic silicone paint containing an ultraviolet absorber. The obtained paint is applied to a glass plate (30
μm) and baked at 120 ° C. for 20 minutes.

From the results shown in Table 5, it can be seen that when the amount of hydrochloric acid added during the preparation of the paste is too large (z-3), the dispersion in the paint is poor. In addition, a mixture of a zinc oxide paste obtained by adding fine particle zinc oxide to a silica-dispersed oligomer solution prepared by partially hydrolyzing a hydrolyzable organosilane into an acrylic silicone paint is more suitable for a hydrolyzable organosilane monomer. It can be seen that the storage stability for a long time is superior to that obtained by adding a paste obtained by directly adding fine-particle zinc oxide to the mixture. On the other hand, the monomer dispersion type is advantageous in that the preparation process is shorter than the oligomer dispersion type. For this reason, it is advisable that the two be used as needed.

[0045]

[Table 5]

[0046]

As described in detail above, according to the invention of this application, it is possible to suppress light deterioration and the like effectively and for a long period of time, to have excellent durability and to be relatively inexpensive. A new highly durable coating composition can be provided.

Claims (7)

[Claims] 1. A coating composition comprising an organic coating applied to a substrate and an overcoat applied to the uppermost layer, wherein the topcoat applied to the uppermost layer is transparent containing an inorganic ultraviolet absorber. A highly durable coating film formed as a silicone resin film. 2. The transparent silicone resin film is a coating film of a composition of one or more of a silicone resin composed of a polymer of a hydrolyzable organosilane and a modified silicone resin. The highly durable coating composition according to claim 1, wherein the coating composition is formed as: 3. The modified silicone resin comprises one or more of an acrylic-modified silicone resin, an epoxy-modified silicone resin, a polyester-modified silicone resin, an alkyd-modified silicone resin, and a phenol-modified silicone resin. The highly durable coating composition according to claim 2, wherein 4. The highly durable coating according to claim 1, wherein the inorganic ultraviolet absorber is a fine particle having a primary particle size of 0.01 to 0.5 μm. Membrane construct. 5. A composition of a silicone resin for forming a transparent silicone resin film, wherein inorganic ultraviolet absorbent fine particles are blended at a ratio of 1 to 30% by weight to a solid content of the composition. The highly durable coating composition according to any one of claims 1 to 4, characterized in that: 6. A silicone-based resin composition for forming a transparent silicone-based resin film is obtained by adding inorganic ultraviolet absorbent fine particles to a hydrolyzable organosilane or a silica-dispersed oligomer prepared by partially hydrolyzing the same. The highly durable coating composition according to any one of claims 1 to 5, wherein the paste obtained is mixed with a silicone resin. 7. The highly durable coating composition according to claim 1, wherein the inorganic ultraviolet absorber is zinc oxide.