JPH03143965A - Weather-resistant coating material - Google Patents

Abstract

PURPOSE:To obtain the title material forming a transparent film with excellent visible light transmittance and weatherability and excellent ultraviolet shielding ability in the form of a thin film by selecting a weather-resistant coating material forming a transparent film wherein specified fine particles are dispersed on the surface of a base material which is protected from ultraviolet deterioration. CONSTITUTION:The surface of a base material which is protected from ultraviolet deterioration (e.g. the surface of a plastic film) is coated with the title coating material forming a transparent film wherein fine particles of an ultraviolet shielding metal oxide pref. zinc oxide are dispersed (e.g. one consisting of an acrylic resin, zinc oxide and methyl ethyl ketone).

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a weather-resistant paint that forms a transparent ultraviolet screening agent film.

[Problems to be solved by the conventional technology and the invention] Weather resistance becomes a problem when used in Ogai when the organic resin fill is 1%.
The yellowing or strength deterioration of organic resin composite materials such as panels, molded products, fiber-reinforced plastics, and Noembla is due to the decomposition of the organic resin structure.The main cause of this is the ultraviolet rays contained in sunlight. Flowers are mentioned. Therefore, if a coating that blocks ultraviolet rays while transmitting visible light every minute is formed on the object 1r, it becomes possible to prevent deterioration and obsolescence without impairing the transparency or color tone of the base material.

Conventionally, the edge method for applying UV shielding agents while maintaining transparency and imparting weather resistance uses benzophenone-based, benzotriazole-based, salicylate-based and substituted acrylic materials.
- Toryl-based exclusive A] Mechanical ultraviolet absorber is blended into the paint,
A method of applying a 1α adhesive film to the object to be protected against ultraviolet deterioration, or directly adding, adhering, or adhering these TJa-based ultraviolet absorbers to the object to be prevented from ultraviolet deterioration. A method is known in which an inorganic ultraviolet shielding agent such as butane oxide is added to a paint and applied directly to the object.

First, apply a paint containing an organic ultraviolet absorber,
A method to improve the weather resistance of the base material will be described. The above-mentioned organic ultraviolet absorbers are easily degraded by ultraviolet rays, and their effects do not last long.In addition, they tend to bleed out and disappear as a result of a diffusion phenomenon than the coating film small binder, and they also tend to be easily lost due to the absorption of ultraviolet rays. The wavelength absorption edge is limited to about 350 nm in most cases, and there are drawbacks such as a narrow UV shielding wavelength range.Also, there is a limit to solubility in various binders, so the amount added is limited to a small amount. Therefore, in order to block enough UV rays, it is necessary to apply a deep coat of paint. It also has the disadvantage of poor thermal stability and cannot be heated or heated at high temperatures.

When forming a coating film on a base material, the concentration of the UV absorber is low due to its low compatibility with the binder resin.
When forming a coating film on J& material, it is necessary to have a coating thickness of 4", so the coating method is limited to screen printing, which can provide a thick coating. Offset printing, gravure printing, etc. cannot handle this, so workability is poor. , printing, and cost are the only problems.

As mentioned above, in the coating method using a paint containing an if-based UV absorber, the UV shielding wavelength range is narrow7, so the IE effect of preventing UV deterioration on the base material is weak, and the UV absorber is The shielding effect itself does not last long because of deterioration and disappearance due to breathing alone. Next, even when adding a good mechanical UV absorber directly to plastic films, panels, molded products, etc., there are concerns that the 4Tha UV absorber itself deteriorates easily, and that the UV absorber is absorbed outside the resin due to breathing. The agent disappears. Due to the low solubility of the ultraviolet absorber in the resin, it is difficult to obtain sufficient ultraviolet absorption ability only near the resin surface. ′, Because ultraviolet rays penetrate into the resin, lateral deterioration of the resin occurs from the surface, causing pod deformation and reduced strength. The direct dispersion of pigments and coloring dyes into resins and the poor coating properties of paints with poor hiding properties make them difficult to use in applications requiring transparency.

Therefore, the technical problem of the present invention is to have a UV shielding ability over a wide range right up to the visible light range, and to have good visible light transmittance (good visibility, excellent weather resistance, and sufficient UV shielding ability with a thin film). It is an object of the present invention to provide a weather-resistant paint that can be applied in large quantities with a low one-stroke process by using coating methods such as gravure printing, off-hit printing, and spraying.

Therefore, an object of the present invention is to provide a weather-resistant paint that has UV blocking ability, good transparency for visible light and other light, and low scattering property.

[Means for Solving the Problems] The present invention is a weather-resistant paint that forms a transparent film in which ultraviolet-shielding metal oxide fine particles are dispersed on the surface of a substrate whose deterioration due to ultraviolet rays is to be prevented. The metal oxide is preferably zinc oxide. Further, the particle size of the zinc oxide is preferably 0.1 μm or less.

In addition, the content of zinc oxide in the solid content of the paint is 5 to 9.
Paints that are 0% by weight are preferred. The transparent film preferably has a haze of 10 or less.

The present inventor, Raso, focused on zinc oxide as an inorganic material that effectively blocks ultraviolet rays, as shown in Figure 1. After preparing the following fine particles-r, they are uniformly dispersed in a binder with a solid content of 5 to 90 weight [iL%] to block ultraviolet rays up to the visible ``X: line'', making them invisible to the eyes. We have discovered that a weather-resistant paint can be made that prevents photodeterioration while transmitting visible light well.

However, the particle size of the zinc oxide used here is 0.1 μm.
If it is more than m, relatively? (Table 1 stone mass per i7π~7 is small, so the ultraviolet shielding ability is low;
Because the light scattering in the IIf visual range is large, the height is high,
[Unable to obtain a weather-resistant paint.

That is, the fine particles of zinc oxide used in the present invention have a particle size of 0.1 μm or less, but considering transparency and ultraviolet shielding properties, preferably 90% of them are 0.005-0. .0
It is preferable that the particles be ultrafine particles that fall within the RJf Fla of 5 μm.

In addition, the amount of zinc oxide ultrafine particles added is 1 + 5 for the solid content of the paint.
If it is less than 9% by weight, the UV shielding ability will be insufficient.
At 0fffffi% or more, the proportion of the binder is too small and a sufficient film cannot be formed. Must be %.

Historically, it is preferably 40 to 80 frL sewing %. Also,
The haze of the transparent film formed by the Weather Resistance Department makes objects on solid surfaces look fresher! It must be less than 10, preferably less than 1, so that it is visible to JJ. There is no limit to the thickness of the transparent film, but from the viewpoint of workability, it is preferably 2.
A film thickness of 0 μm or less is preferable, but historically, a film thickness of 1 to 5 μm, which can be used by gravure printing or offset printing, is more suitable for HF.

As a result, a coating film made of a weather-resistant paint in which ultrafine zinc oxide particles are uniformly dispersed in a binder can shield ultraviolet rays evenly, while at the same time shielding the entire wavelength range of +4 visual potential. It exhibits high transmittance throughout the film and has excellent transparency.

Oxidized lead fine particles having such properties are, for example,
It can be manufactured by the method described in Specification I Town of Special Ff Application No. 130422 of 1999.

The zinc oxide powder having a particle size of 0.1 μm or less used in the present invention can be produced by a vapor phase evaporation-precipitation method, heat treatment of fine particles of zinc oxide of 20 Å or less, or the like.

-'JJ', When the binder is used as a paint, it has excellent weather resistance (YI), is resistant to deterioration by ultraviolet rays, and has a high transparency of 1! It must be able to form a film that has IJW characteristics and at the same time has excellent 145 youthfulness relative to the object to be coated.

Types of binders that have the properties listed in 1- are:
Any ordinary organic binder or inorganic binder can be used, such as polyester resin type, vinyl resin type, acrylic resin type, fluorine resin type, silicone resin type, alkaline binder such as IL acid soda, etc. cate-based, inorganic-J L'lid-based such as linica sol and alumina sol,
Examples include metal alkoxide systems such as detraethine ciscine, phosphate systems such as aluminum phosphate, metal salt systems such as tin acetate, metal soap systems, and metal compound systems.

Alternatively, two or more of the materials listed below may be mixed or reacted to be used as a binder.

, E, these binders are selected from aromatic hydrocarbons, alecols, esters, ketones, needles, saturated hydrocarbons, chlorinated carbons, fluorinated carbons, and water. It is used by dissolving or dispersing one or two persimmons in a solvent.

Furthermore, the fine particles of zinc oxide need to be uniformly dispersed in the binder, and for this purpose, e.g.
A gamma triter, a sand glider, a high-speed impeller mill, a jet mill, a nida, a paint seeker, a homogenizer, a super) f-crossing dispersion machine, etc. are used in conjunction with tp and my paper. In addition, one type of lead oxide fine particles selected from 41 acid type, Campling type, surfactant, metal soap type, metal salt type, alkaline dinocate type, phosphate type, metal alkoxide type, etc. Alternatively, it is preferable to use two or more kinds to further promote dispersibility.

Next, the method for applying the weather-resistant paint described in No. 011 will be explained. , brush painting, spin: 1-F,
Gravure printing, offset printing, spray method, doctor blade, bar twoter, letterpress printing, screen printing,
A transparent film can be formed by pad printing, planographic printing, flexo printing, etc. In addition, as the base material of the object, plastic film, plastic panel, white glass 7
Examples include molded products, FRP products, engineering plastic products, etc., and there are no restrictions on the shape of the object.

The paint of the present invention uses a binder to provide fluidity and film strength! Since it is necessary for j1 to fill in the spaces between ZnO particles, zinc oxide accounts for 90% of the solid content.
It is preferably less than % by weight. Otherwise, the coating becomes extremely brittle. Furthermore, if the zinc oxide content is less than 5π■%, the proportion of light that does not pass through the zinc oxide increases, which is undesirable because the ultraviolet absorption efficiency decreases.

The coating film produced using the coating film-forming material of the present invention not only has excellent ultraviolet blocking properties, but also has excellent translucency, sanitary properties, weather resistance, and the like.

Next, the highly translucent weather-resistant paint according to the present invention will be specifically explained with reference to Examples, but the present invention is not limited thereto.

[Example 1 15 parts of core acrylic resin, 15 parts by weight of zinc oxide with a particle size of 0.1 μm or less (average particle size 0.01 μm), and 7 parts of methyl ethyl ketone were mixed, and mixed in a sand mill for 2 hours. The mixture was stirred and dispersed to prepare a weather-resistant paint.

[Example 2] 13 parts by weight of fine particle zinc oxide (average particle size 0.01 μm),
A weather-resistant paint was prepared by stirring and mixing 15 parts by weight of fluorine resin and 40 parts of butyl acetate in a sand mill for 3 hours.

[Comparative Example 1] 2,4-dihydre L, a benzophenone ultraviolet absorber
A weather-resistant paint was prepared by mixing 5 parts by weight of 1-quinbenzophenone, 45 parts by weight of acrylic resin, and 60 parts by weight of medel ethyl ketone in a Nando mill for 2 hours.

[Comparative Example 2] In Example 1, fine particles of zinc oxide were replaced with fine particles of titanium oxide (f average particle size: 0.03 μm), and other than that, a fly was created using the same formulation and dispersion H method.

[Comparative Example 3] 100 parts by weight of polyethylene terephthalate was blended with 0.3 parts by weight of 2-hydroquine-4-melquin benzophenone as an ultraviolet absorber, a sheet was prepared by a known method, and this sheet was cut lengthwise into 3 parts. The film was stretched .5 times and 3.5 times horizontally to obtain a film with a thickness of 100 μm.

[e/i cloth, test] The following film was created using the paint created above.

The paint prepared in Example 1 was applied to a 100 μm thick polyethylene terephthalate film by gravure printing to a dry film thickness of 3 μm to prepare a sample.

Next, the paint prepared in Example 2 was applied onto the surface of a 100 μm thick polyethylene prephthalate film by gravure printing to a dry film thickness of 4 μm to prepare a sample.

Next, the paint prepared in Comparative Example 1 was applied onto a transparent polyethylene terephthalate (PET) film (thickness: 100 μm) using a reverse-1-ting method to give a dry film thickness of 30 μm, thereby preparing a sample.

The paint prepared in Comparative Example 2 was applied by gravure printing onto the surface of a 100 μm thick bot ethylene terephthalate film to a dry film thickness of 3 μm to prepare a sample.

The film obtained in Comparative Example 3 was used as a sample.

First, the reflection ratio was measured against wavelength for fine particles of titanium oxide (ie, used in Comparative Example 2) and fine particles of zinc oxide (used in Example 1), and the results are shown in the graph of FIG.

Next, the spectral transmittance of each film coated with the paint prepared in each of the Examples and Comparative Examples as described above was measured. The results are shown in FIG.

Furthermore, weather resistance tests were conducted on each of the above films. That is, each of the above films was placed outdoors at a research institute in Funabashi City, Chiba Prefecture for two years from January 1980 to January 1999, and an outdoor exposure test was conducted. The spectral transmittance, haze value, and tensile strength were measured before the exposure test, and after the exposure test,
Its spectral transmittance, haze value, and tensile strength were measured. The results are shown in Table 1.

Figure 1 shows the reflectance curves of fine-particle oxide (Ifi lead) and fine-particle butane oxide.The fine-particle zinc oxide used in the present invention does not absorb in the visible light range, and in the ultraviolet region, it absorbs almost all wavelengths below 380 nm. (11) line.On the other hand, fine particle titanium oxide shows a line of 3.
There is almost no absorption in the wavelength range of 50 to 380 nm, and the effect of preventing ultraviolet deterioration is weak.

FIG. 2 is a graph showing the results of measuring the spectral transmittance of the gold films coated with the weather-resistant paint of the present invention and the comparative paint, using the coating materials of Example 1.2 and Comparative Example 1.2.30. be.

In the spectral transmittance curve shown in Figure 2, the filters coated with paints containing fine particles and zinc oxide in Examples 1 and 2 transmit visible light well over the entire range, while in the ultraviolet range,
Sharp absorption] 111 line is shown, and the absorption edge is 385
It turned out that it was around nm. On the other hand, in the film prepared by applying the paint containing the benzophenone ultraviolet absorber in Comparative Example 1 and the film prepared in Comparative Example 3 containing the benzophenone ultraviolet absorber in the film paste, absorption started slightly from the visible range. , a gentle absorption IIh line is drawn, and its absorption edge is at 360 to 340 nm. In the film made using titanium oxide of Comparative Example 2, absorption begins at around 500 nm in the visible range and then shows a gentle absorption curve in the ultraviolet range, with the absorption edge at around 330 nm. From the second point onwards, by using fine particles of zinc oxide as an ultraviolet absorber, it is possible to effectively transmit b-division light, and at the same time, it is effective over a wide range of ultraviolet rays. ! ! It is possible to create weather-resistant paints that exhibit abrasive properties.

Next, in Table 1, which is the result of the outdoor exposure test, Example 1
．． The film coated with the paint No. 2 remains strong even after being exposed outdoors.
There was almost no decrease in the ultraviolet shielding effect, and the visible light transmittance was only slightly reduced, so the transparency was almost unchanged and the tensile strength was only slightly decreased. be. On the other hand, in Comparative Example 1, which is a coated film using an organic UV absorber, and Comparative Example 3, which is a coating film in which an organic UV absorber is mixed, the transmittance at 365 nm, which is a measure of the UV shielding effect after the outdoor @ dew test, has increased. The effectiveness is significantly reduced. Furthermore, at the same time, a decrease in transmittance at 550 nm was observed, indicating that transparency was also beginning to be lost. As described above, since the ultraviolet shielding effect has weakened, deterioration of the film due to ultraviolet rays contained in sunlight progresses, and a significant decrease in tensile strength is observed.

The above tendency was more remarkable in Comparative Example 1.

In Comparative Example 3 using titanium oxide, since it is an inorganic UV absorber, the change over time is relatively small, so the UV shielding function of the coating film is affected, and although the deterioration as a film is suppressed to a certain degree, In terms of ultraviolet shielding effect and transparency, it is considerably inferior to when zinc oxide is used.

[Effects of the Invention] As explained above, the present invention has zinc oxide fine particles with a particle size of 0.1 μm or less dispersed in a binder at 5 to 90% by weight in the solid content of the paint so as to have a haze of 10 or less. The weather-resistant paint produced the following remarkable technical effects.

First, this paint is applied to the base material, I:, and even if the thin film that is formed after drying is, for example, 2 to 3 μm, it covers a wide range of spaces and blocks ultraviolet rays, while at the same time transmitting visible light well. ,
Moreover, it becomes possible to form a coating film with excellent weather resistance.

Second, by applying this paint to various objects for which it is desired to suppress ultraviolet deterioration, it is possible to easily and inexpensively bring about two effects in terms of the amount of ultraviolet deterioration.

Thirdly, as a result, an economical weather-resistant coating material that can maintain the added value of objects for a longer period of time can be provided.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the results of measuring the reflectance of fine particle zinc and titanium oxide used in the present invention. FIG. 2 is a graph showing the spectral transmittance +11+ line of a coating film formed by applying the weather-resistant paint of the present invention in comparison with a comparative example.

Claims (1)

[Scope of Claims] 1. A weather-resistant paint that forms a transparent film in which ultraviolet-shielding metal oxide fine particles are dispersed on the surface of a base material that is to be prevented from degrading by ultraviolet rays. 2. The weather-resistant paint according to claim 1, wherein the metal oxide is zinc oxide. 3. The weather-resistant paint according to claim 2, wherein the particle size of the zinc oxide is 0.1 μm or less. 4. The content of the zinc oxide in the solid content of the paint is 5 to 9.
The weather-resistant paint according to claim 2, which has a content of 0% by weight. 5. Claim 1, wherein the transparent film has a haze of 10 or less.
Weather-resistant paint as described in section.