JPH04239038A - Silicon dioxide coated body and its production - Google Patents

Abstract

PURPOSE:To prepare a coated body by coating a plastic molding or a like base with a silicon dioxide film having durability and a uniform thickness. CONSTITUTION:A silicon dioxide-coated body is prepared by forming on a plastic molding or a like base (a) a layer (b) prepared by applying and curing at least one silicon compound selected from the group consisting of an organosilane, its hydrolyzate and colloidal silica, a layer (c) of a silicon dioxide film formed by bringing an aqueous hydrosilicofluoric acid solution (i) supersaturated with silicon dioxide and having a specified silicon concentration into contact with the layer (b) and a layer (d) of a silicon dioxide film formed by bringing an aqueous hydrosilicofluoric acid solution (ii) supersaturated with silicon dioxide and having a silicon concentration higher than that of the solution (i) into contact with the layer (c) in the given order.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a plastic molded article,
Regarding methods for improving surface conditions such as surface hardness, weather resistance, and chemical resistance of substrates such as metal plates, or methods for suppressing water absorption and gas permeability of plastic moldings, etc., especially for plastic moldings and other substrates. The present invention relates to a method for forming a highly durable silicon dioxide film on a surface.

0002

[Prior Art] In recent years, silicon dioxide film deposition methods have been developed with the following advantages: 1. Low-temperature deposition is possible. 2. Deposition costs are low because no vacuum system is required. 2. Large-area, large-volume deposition is possible. Due to its advantages, a method of forming silicon dioxide on the surface of a substrate by bringing the substrate into contact with a supersaturated aqueous solution of hydrosilicic fluoric acid (hereinafter referred to as the "precipitation method") is attracting attention (
For example, JP-A-60-33233, JP-A-62-208
76).

In particular, regarding the method of forming a silicon dioxide film on a plastic molded body by a precipitation method, the plastic molded body is coated with organic silicon compounds and their hydrolysates and cured to form a primary film, and then the silicon dioxide film is formed by a precipitation method. A method of forming a silicon dioxide film on a primary film is known (for example, JP-A-61-12734).

0004

[Problem to be Solved by the Invention] Normally, even if attempts are made to form a silicon dioxide film on an untreated plastic surface by a precipitation method, silicon dioxide is not obtained in the form of a film, but particles are attached to the surface. appear. This is presumed to be because there is no site on the plastic surface for reaction with the silicon species in the hydrosilicofluoric acid aqueous solution. Japanese Patent Publication No. 61-12734
The primary coating described in 2. provides a base for reaction with the silicon species in the aqueous solution of hydrosilicofluoric acid, so by covering the plastic molded article with the primary coating in advance, It has become possible to obtain silicon dioxide in the form of a film using the precipitation method.

However, if the conditions of the precipitation method (film-forming temperature, hydrosilicofluoric acid concentration) are changed in order to improve the film quality of the silicon dioxide film obtained by the precipitation method, the primary film is deposited on the plastic surface in advance. Even if a silicon dioxide film is formed, depending on the conditions of the precipitation method, a silicon dioxide film may not be obtained, or even if it is obtained, it becomes cloudy.

The present invention solves the above-mentioned conventional problems and provides a coating in which a plastic molded article or other substrate is covered with a highly durable and uniformly thick silicon dioxide coating, and a method for manufacturing the same. purpose.

[0007]

[Means for Solving the Problems] The present invention provides a substrate formed by coating and curing at least one silicon compound selected from the group consisting of a) a substrate, b) organosilanes, their hydrolysates, and colloidal silica. c) a layer of a silicon dioxide coating formed by contacting the b) layer with an aqueous solution of hydrosilicofluoric acid (a) having a predetermined silicon concentration in which silicon dioxide is supersaturated; and d) a silicon dioxide coating layer in which silicon dioxide is supersaturated. of a silicon dioxide coating formed by contacting the layer c) with an aqueous silicofluoric acid solution (b) which is in a state of The gist is a silicon dioxide coated body formed by laminating layers a), b), c) and d) in this order.

The present invention will be explained in detail below. The substrate used in the present invention may be a plastic molded body, a metal plate, etc., but examples of the plastic molded body include, but are not limited to, polyvinyl chloride, polystyrene, polycarbonate, polymethyl methacrylate,
From thermoplastic resins, elastomers, and polymer blends thereof, such as polyamide, polyacetal, polybutylene terephthalate, polyethylene, polypropylene, aromatic polyester, polyether ketone, polyimide, polyacrylonitrile, polyphenylene sulfide, polyphenylene oxide, polysulfone, etc. It is a thermosetting resin molded body represented by polydiethylene glycol bisallyl carbonate, phenol resin, etc. The shape and size of the molded body are arbitrary.

In the present invention, the organosilane used for forming layer b) is typically represented by the general formula (1).
Examples include silicon compounds represented by
Dimethyldimethoxysilane, methyltrimethoxysilane, tetraethoxysilane, phenyltrimethoxysilane, phenylmethyldimethoxysilane, vinyltriethoxysilane, vinyltris(β-methoxyethoxy)silane, vinyltriacetoxysilane, γ-methacryloxypropyltrimethoxysilane , γ-aminopropyltriethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyl(methyl)dimethoxysilane, N-bis(β-aminoethyl)-γ-aminopropyl(methyl)dimethoxysilane, -hydroxyethyl)-γ-aminopropyltriethoxysilane, γ-chloropropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, β
Typical examples include -(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3,3,3-trifluoropropyltrimethoxysilane, methyltrichlorosilane, and dimethyldichlorosilane. In addition, the hydrolyzate of the silicon compound represented by the general formula (1) refers to a silicon compound in which a part or all of the alkoxy group, alkoxyalkoxy group, acyloxy group, or chlorine element is substituted with a hydroxyl group, and some naturally condensed substituted hydroxyl groups. These hydrolysates can be obtained, for example, by hydrolysis in a mixed solvent such as water and alcohol in the presence of an acid.

[0010] Colloidal silica also refers to particles with a particle size of 1 to 1
It is a sol prepared by dispersing ultrafine silica particles of 0.00 mm in diameter in water or an alcohol-based dispersion medium, or a dry powder obtained by removing the dispersion medium from this sol, and commercially available products can be used. In the present invention, layer b) is formed on a plastic molded body or other substrate using at least one silicon compound selected from the group consisting of organosilanes, their hydrolysates, and colloidal silica, and the method for forming the layer b) may be a wet method in which it is applied as a paint and then dried using heat, ultraviolet rays, or electron beams, or a dry method such as vacuum evaporation, ion plating, sputtering, or plasma polymerization; The wet method is preferable for forming a film on a shaped plastic molded body.

The thickness of the layer b) to be formed is not particularly limited, but is usually preferably in the range of 0.1 to 10 μm. If the thickness of this coating layer is too small, the adhesion of the silicon dioxide film obtained by the subsequent precipitation method tends to decrease, which is not appropriate. On the other hand, if it is excessive, it is uneconomical. However, if a silicon compound having an amino group is used for the polycarbonate base, and a silicon compound having a methacryloxy group is used for the polymethyl methacrylate base, b
) Even if the layer is as thin as several nanometers to 0.1 μm, the adhesion of the silicon dioxide film obtained by the subsequent precipitation method is strong. In addition, if the base is a plastic molded body,
In order to further improve the adhesion of layer b), before forming b), the plastic substrate surface is modified by corona discharge treatment, plasma treatment, ultraviolet irradiation, etc., or a resin primer layer is formed in advance. You can leave it as is.

The plastic molded article or other substrate on which the layer b) has been formed as described above is then brought into contact with supersaturated aqueous solutions of hydrosilicofluoric acid (a) and (b) of silicon dioxide, and b) A silicon dioxide coating is formed over the layer. Generally, properties such as density and refractive index of the silicon dioxide film obtained are greatly influenced by the concentration of hydrosilicofluoric acid and temperature. Generally, the higher the concentration of hydrosilicic fluoric acid and the higher the film formation temperature, that is, the temperature of the aqueous solution of hydrosilicic fluoric acid, the denser the silicon dioxide coating can be obtained.

However, in order to obtain a dense silicon dioxide film on the substrate on which layer (b) has been formed, if a highly concentrated aqueous solution of hydrosilicofluoric acid is used or film formation is attempted at high temperature, the layer (b) A silicon dioxide coating cannot be obtained by dissolving in an aqueous solution of hydrosilicofluoric acid. (2) Even if a silicon dioxide coating is obtained, there are problems such as uneven thickness, cloudy, and uneven thickness.

In the present invention, the substrate on which the layer b) is formed is first brought into contact with an aqueous solution of hydrosilicofluoric acid (a) having a predetermined silicon concentration, preferably a silicon concentration of 2.0 mol/liter or less. After forming the silicon dioxide coating (layer (c)), the silicon fluoride film is formed to have a silicon concentration higher than that of the hydrosilicofluoric acid aqueous solution (a), preferably a silicon concentration of 2.5 mol/liter or more. A transparent and uniform silicon dioxide coating (layer d) is obtained by contacting with an aqueous hydrogen acid solution (b). The silicon concentration of the hydrosilicofluoric acid aqueous solution (b) is preferably 0.6 to 2.5 mol/liter higher than the silicon concentration of the hydrosilicofluoric acid aqueous solution (a).

[0015] Contact with the hydrosilicofluoric acid aqueous solution (a) is carried out at 30°C.
It is preferable to carry out the liquid temperature below, usually 15 to 3
Contact is made for 10 minutes to 200 minutes at a liquid temperature of 0°C. If the thickness of the layer c) is usually 10 to 50 nm, for example 20 nm, then a uniform layer d) can be coated thereon. If the contact temperature of the hydrosilicofluoric acid aqueous solution (a) is T1℃, the contact temperature of the hydrosilicofluoric acid aqueous solution (b) is (T1℃+5℃
) or higher, particularly at a liquid temperature of 25°C or higher, and usually at a liquid temperature of 30 to 50°C for 30 minutes to 300 minutes.
contact for minutes. d) The preferred thickness of the layer is 50 to 300
It is nm. The contact with the hydrosilicofluoric acid aqueous solution is not limited to the above two times, but may be performed three or more times. In this case, it is preferable that the silicon concentration of the liquid be increased in sequence, with the silicon concentration of the first liquid being the value of (a) above, and the silicon concentration of the last liquid being the value of (b) above.

FIG. 1 shows a system diagram of the silicon dioxide coating manufacturing apparatus used in the present invention. In FIG. 1, the immersion tank consists of an outer tank 1 and an inner tank 2, and the space between the inner tank 1 and the outer tank 2 is filled with water 3. This water is heated with a heater 4 to maintain a constant temperature, and is heated with a stirrer 5 to make the temperature distribution uniform.
is being stirred.

The inner tank 2 consists of a front part 6, a middle part 7, and a rear part 8, and each part is filled with an aqueous solution of hydrosilicofluoric acid of a predetermined concentration in which silicon dioxide is dissolved and saturated using industrial silica gel powder as a source of silicon dioxide. It is filled with 6.5 liters. here,
The three-way cocks 13a, 13a', 13b, and 13b' are adjusted, and the circulation pump 12a is operated to pump out a certain amount of the reaction liquid from the rear part 8 of the inner tank, filter it with the filter 11a, and then transfer it to the inner tank 6.
Start circulating the processing liquid back to the Here, the mesh of the filter 11a is 1.5 μm, and the reaction liquid circulation flow rate is set to 520 cc/min (since the total amount of reaction liquid is 6.5 liters, the circulation flow rate is about 8%/min).

[0018] After that, the length is 50 mm, the width is 50 mm, and the thickness is 3.
Three aluminum plates 15 with a diameter of 3 mm are immersed in the rear part 8 of the inner tank, and the stirrer 16 is activated to promote dissolution of the aluminum plates. By maintaining this state for 16 to 30 hours, the reaction solution becomes a processing solution having an appropriate degree of silicon dioxide saturation (capable of forming a silicon dioxide film). The silicon concentration in the reaction solution is measured directly by plasma emission spectroscopy after sampling the reaction solution and cooling it at a temperature of 10° C. or lower for about 10 hours.

When the reaction solution has the ability to form a silicon dioxide film, silicon dioxide is generated in the reaction solution as particles, grows, and is eventually filtered by the filter 11a, causing clogging of the filter. After aluminum addition 3
This tendency is observed after 0 to 50 hours have elapsed, leading to a decrease in the circulating flow rate. Therefore, after returning the reaction liquid in the piping and filter 11a to the inner tank 2, the circulation of the reaction liquid is started at the rear part of the inner tank.
, filter 11b, circulation pump 12a, and inner tank front part 6 in this order: three-way cocks 13a, 13a', 13b,
13b' and restarting the circulation of the reaction liquid, the circulation flow rate of the reaction liquid is restored to 520 cc/min. Here, the mesh of the filter 11b is 1.5 μm, same as the filter 11a.

In this state, the circulation pump 12b is operated,
5% hydrofluoric acid aqueous solution 10 is in cleaning liquid tank 9, filter 1
1a, circulation pump 12a, and cleaning liquid tank 9 in this order, the clogged filter 11a is cleaned and regenerated. In accordance with the above procedure, the three-way cocks 13a, 13a', 13b,
A silicon dioxide coating can be continuously obtained by immersing a plastic molded body coated with various silicon compounds in the inner tank middle part 7 for a predetermined time while adjusting the filter 13b' and switching the filter.

[0021]

EXAMPLES The present invention will be explained in detail below with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples unless it exceeds the gist thereof. Example 1, Comparative Example 1 First, γ-glycidoxypropyltrimethoxysilane
350 parts by weight, water-dispersed colloidal silica (manufactured by Nissan Chemical Co., Ltd., trade name Snowtex-C, solid content 20%)
14 parts by weight, 9 parts by weight of distilled water, and 3 parts by weight of a 1.2N aqueous hydrochloric acid solution were mixed and refluxed at 80°C for 4 hours, and then 57 parts by weight of the solvent was distilled at a distillation temperature of 80 to 90°C. Hydrolyzate solution of γ-glycidoxypropyltrimethoxysilane containing colloidal silica thus obtained 66
A paint was prepared by adding 100 parts by weight of ethyl cellosolve, a curing catalyst, and a small amount of a flow control agent. Apply this paint to a surface of 100 mm long and 100 mm wide that has been cleaned in advance.
．． It was coated on a 1 mm polydiethylene glycol bisallyl carbonate (hereinafter referred to as CR-39) flat plate by a dipping method, and heat-treated in a hot air drying oven at 120°C for 30 minutes. CR-
A layer b) having a thickness of 4 μm was formed on the No. 39 flat plate.

The CR-39 flat plate on which the above b) layer was formed was immersed in the interior middle part 7 of the silicon dioxide coating production apparatus shown in FIG. 1, and then held for 30 minutes to remove the silicon dioxide coating (
c) layer) was created. The concentration of the hydrosilicofluoric acid aqueous solution circulating in the silicon dioxide coating manufacturing apparatus is 1.2 mol/liter, and the temperature during film formation is adjusted to 3.2 mol/liter by adjusting the heater 4.
The temperature was kept at 0°C.

As described above, a silicon dioxide coating (layer c) having excellent transparency and uniformity was obtained on the CR-39 flat plate. The thickness of the coating was examined and found to be approximately 30 nm. b above
) layer and c) layer laminated in this order (Example 1), and CR-39 flat plate coated with only layer b) (
Comparative Example 1) was immersed in the interior middle part 7 of the silicon dioxide coating manufacturing apparatus shown in FIG. 1, and then held for 60 minutes. The concentration of the hydrosilicofluoric acid aqueous solution circulating in the silicon dioxide coating manufacturing apparatus was 3.2 mol/liter, and the heater 4 was adjusted so that the temperature during film formation was 32°C.

CR in which layer b) and layer c) are laminated in this order
-39 flat plate has a transparent and uniform silicon dioxide coating (d) layer)
was formed. The thickness of the obtained layer d) was examined and found to be approximately 70 nm. That is, on the CR-39 plate, c
This means that a silicon dioxide coating of about 100 nm was obtained by combining layers ) and d). However, C coated with only layer b)
It was confirmed by measuring the contact angle that the surface of the R-39 flat plate was hydrophobic, and the formation of a silicon dioxide coating (layer d) was not observed when the fracture surface was observed using an electron microscope.

[0025] The silicon dioxide coating (c) layer plus d
) Layer ) had a strong adhesive strength that did not peel off at all in a test in which cellophane adhesive tape was attached and peeled off. In addition, even though it was immersed in boiling water for 1 hour, there was no change in adhesive strength.

Example 2, Comparative Example 2 First, an undercoating liquid was prepared according to the following procedure. First, 240 parts by weight of methyl isobutyl ketone, 160 parts by weight of methacrylic acid.
Parts by weight, while maintaining a mixture of 40 parts by weight of γ-methacryloxypropyltrimethoxysilane at 75°C under a nitrogen atmosphere, a solution of 0.5 parts by weight of benzoyl peroxide dissolved in 60 parts by weight of methyl isobutyl ketone was prepared over a period of 2 hours. added. After maintaining the same temperature for an additional 2 hours, a solution of 0.5 parts by weight of benzoyl peroxide dissolved in 60 parts by weight of methyl isobutyl ketone was added over 1 hour, and the mixture was kept at 75°C for 4 hours. Then 750 parts by weight of methyl isobutyl ketone, 240 parts by weight of methyl ethyl ketone, 630 parts by weight of isopropanol, 2
-(2'-hydroxy-di-t-butylphenyl)-5
-20 parts by weight of chlorobenzotriazole was added. This solution will be referred to as copolymer solution 1.

On the other hand, 221 parts by weight of γ-aminopropyltriethoxysilane was added to 178 parts by weight of methyl nadic anhydride while maintaining the temperature at 70°C over a period of 1 hour.
After keeping warm for an hour, 530 parts by weight of ethanol and 1070 parts by weight of isopropanol were added. This solution will be referred to as silane solution 1. and 10% copolymer solution 1
0 parts by weight and 10 parts by weight of silane solution 1 were mixed to prepare an undercoat, and this undercoat was applied to a previously washed polycarbonate substrate and dried by heating at 120° C. for 30 minutes in a hot air drying oven. A 5 μm thick undercoat layer was formed on this substrate.

Next, a top coat for layer b) to be applied on the base coat was prepared in the following manner. First, γ−
Glycidoxypropyltrimethoxysilane 80 parts by weight, methyltrimethoxysilane 144 parts by weight, colloidal silica (manufactured by Nissan Chemical Industries, Ltd., trade name Snowtex-C, solid content concentration 20%) 71 parts by weight and 0.1 normal Mix 170 parts by weight of hydrochloric acid aqueous solution,
Hydrolysis was carried out by refluxing at ~85°C for 2 hours.

To 410 parts by weight of the ternary cohydrolyzate solution thus obtained, 3 parts by weight of ethyl cellosolve 7,
A top coat was prepared by adding 1.3 parts by weight of ammonium perchlorate and a small amount of a flow control agent. The top coat thus obtained was applied onto the polycarbonate coated with the undercoat layer and cured by heating at 130° C. for 60 minutes in a hot air drying oven. The thickness of this topcoat was approximately 5 μm, and the total thickness of layer b) was 10 μm.

An attempt was made to form a silicon dioxide coating (layer c) by a precipitation method on a polycarbonate flat plate on which layer b) had been formed using the above double coating method. The concentration of the hydrosilicofluoric acid aqueous solution was 1.5 mol/liter, and the film was formed at a temperature of 27° C. for about 50 minutes. A silicon dioxide coating (layer c) with excellent transparency and uniformity was obtained on the polycarbonate flat plate. The thickness of the coating was examined and found to be approximately 40 nm.

A polycarbonate flat plate in which the b) layer and c) layer were laminated in this order (Example 2) and a polycarbonate flat plate in which the c) layer was not formed (Comparative Example 2) were
After being immersed in the interior middle part 7 of the silicon dioxide coating manufacturing apparatus shown in FIG. 1, it was held for 120 minutes. Note that the concentration of the hydrosilicofluoric acid aqueous solution was 4.0 mol/liter, and the temperature during film formation was 32°C.

A transparent uniform silicon dioxide coating (layer d) was formed on a polycarbonate flat plate in which layers b) and c) were laminated in this order. The thickness of the obtained layer d) was examined and found to be approximately 160 nm. That is, a silicon dioxide coating having a total thickness of about 200 nm was obtained on the polycarbonate flat plate, including layers c) and d). However, the surface of the polycarbonate flat plate on which layer c) was not formed was still hydrophobic, and no formation of the silicon dioxide film (layer d) was observed.

The silicon dioxide coating (layer c) plus layer d) had such strong adhesion that it did not peel off at all in a test in which cellophane adhesive tape was applied and peeled off. In addition, even though it was immersed in boiling water for 1 hour, there was no change in adhesive strength.

Example 3, Comparative Example 3 10 parts by weight of γ-aminopropyltriethoxysilane was diluted with 1000 parts by weight of isopropyl alcohol.
) It was used as a coating liquid for layer formation. This coating solution was applied by dipping onto a polycarbonate flat plate measuring 100 mm long, 100 mm wide and 1.1 mm thick, which had been cleaned in advance, and then dried in a hot air drying oven at 80°C for 30 minutes.
Heat treatment was performed for 0 minutes. Approximately 15 on the polycarbonate plate
A layer b) of nm was formed.

The polycarbonate flat plate on which the layer b) was formed was immersed in the interior middle part 7 of the silicon dioxide coating production apparatus shown in FIG. 1, and then held for 30 minutes to form a silicon dioxide coating (layer c). Note that the concentration of the hydrosilicofluoric acid aqueous solution circulating in the silicon dioxide film manufacturing apparatus is 1.
8 mol/liter, and the heater 4 was adjusted so that the temperature during film formation was 30°C.

As described above, a silicon dioxide coating (layer c) having excellent transparency and uniformity was obtained on a polycarbonate flat plate. The thickness of the coating was examined and found to be approximately 30 nm. A polycarbonate flat plate (Example 3) in which the above b) layer and c) layer were laminated in this order, and a polycarbonate flat plate (Comparative Example 3) coated with only the b) layer were used in the interior of the silicon dioxide coating manufacturing apparatus shown in Fig. 1. After being immersed in the middle part 7, it was held for 60 minutes. In addition, the concentration of the hydrosilicofluoric acid aqueous solution circulating in the silicon dioxide film manufacturing apparatus is 2.5 mol / liter,
The heater 4 was adjusted so that the temperature during film formation was 40°C.

A transparent and uniform silicon dioxide coating (layer d) was formed on the polycarbonate flat plate in which layers b) and c) were laminated in this order. The thickness of the obtained layer d) was examined and found to be approximately 70 nm. That is, a silicon dioxide film having a total thickness of about 100 nm was obtained on the polycarbonate flat plate by layer c) and layer d). However, the surface of the polycarbonate plate coated with only layer b) was still hydrophobic, and no formation of a silicon dioxide film (layer d) was observed.

[0038] The silicon dioxide coating (c) layer plus d
) Layer ) had a strong adhesive strength that did not peel off at all in a test in which cellophane adhesive tape was attached and peeled off. In addition, even though it was immersed in boiling water for 1 hour, there was no change in adhesive strength. From the results of Examples 1 to 3 and Comparative Examples 1 to 3, it can be seen that the formation of layer c) enables the formation of a silicon dioxide film on the surface of the plastic molded body even under all conditions of the precipitation method.

Examples 4 to 6, Comparative Examples 4 to 6 10 parts by weight of γ-aminopropyltriethoxysilane was diluted with 1000 parts by weight of isopropyl alcohol to prepare a coating solution for forming layer b). A length of 100 mm was cleaned in advance with this coating solution.
Polycarbonate flat plate, 100mm wide and 1.1mm thick.
Then, it was applied by dipping onto a polycarbonate film measuring 100 mm long, 100 mm wide and 100 μm thick, and heat-treated in a hot air drying oven at 80° C. for 30 minutes. polycarbonate flat plate,
A layer b) of about 15 nm was formed on the film.

The polycarbonate flat plate and film on which the above b) layer was formed were immersed in the interior middle part 7 of the silicon dioxide coating manufacturing apparatus shown in FIG. 1, and then held for 20 minutes to form a silicon dioxide coating (layer c). did. The concentration of the hydrosilicofluoric acid aqueous solution circulating in the silicon dioxide film manufacturing apparatus was 1.5 mol/liter, and the heater 4 was adjusted so that the temperature during film formation was 28°C.

As described above, a silicon dioxide coating (layer c) having excellent transparency and uniformity was obtained on a polycarbonate flat plate. The thickness of the coating was examined and found to be approximately 20 nm. The polycarbonate flat plate and film in which the above b) layer and c) layer were laminated in this order were placed in the interior middle part 7 of the silicon dioxide film manufacturing apparatus shown in Fig. 1 under the conditions of each precipitation method shown in Table 1 (30°C , concentration 2.5-4.0 mol/liter) for about 60-100 minutes to form a transparent silicon dioxide film (d) layer) with a uniform thickness of 100 nm each on the polycarbonate flat plate and film. did. A transparent and uniformly thick layer d) was formed on the polycarbonate plate and film.

[0042] The silicon dioxide coating (c) layer plus d
) Layer ) had a strong adhesive strength that did not peel off at all in a test in which cellophane adhesive tape was attached and peeled off. In addition, even though it was immersed in boiling water for 1 hour, there was no change in adhesive strength.

[0043] The water absorption rate of each obtained polycarbonate flat plate was determined based on the JISK-6911 method, and the water vapor permeability of the polycarbonate film was determined based on the JISZ-0208 method (
40° C., 90% RH). Results first
Shown in the table. For comparison, Table 1 includes Comparative Examples 4 and 5, which were obtained under the conditions of the d) layer precipitation method at 30°C and a concentration of 1.0 to 2.0 mol/liter, and untreated samples. The measurement results for the polycarbonate flat plate and polycarbonate film are also listed as Comparative Example 6. From Table 1, it is inferred that the silicon dioxide coating created using a treatment liquid with a higher silicon concentration is denser and has higher gas barrier properties.

Comparative Examples 7 to 9 An attempt was made to form the d) layer directly on the b) layer in exactly the same manner as in Examples 4 to 6 except that the c) layer was not formed. The results are shown in Table 2. From the results in Table 2, it can be seen that unless layer c) is formed, it becomes difficult to obtain a silicon dioxide film as the silicon concentration of the treatment liquid increases. That is, from the results of Examples 4 to 6 and Comparative Examples 7 to 9, it is clear that the formation of layer c)

[0045]
Table 1
Deposition method conditions Film forming temperature
Treatment liquid concentration Moisture permeability
Water absorption rate (℃
) (mol/liter) (g/24hr・m2)
(%) −−−−−−−−−−−−−−−−−
−−−−−−−−−−−−−−−−−−−−−−−−−
−−−−−−−−−−−−−−−−−−−−−−−−−
-- Comparative example 4 30 1
．． 0 28.7
0.31 Comparative example 5 30
2.0 12.0
0.20 Example 4 30
2.5
2.67 0.07 Example 5
30 3.0
1.97 0.03 Example 6 30 4.0
1.88 0.
02 Comparative Example 6 -----
------ 30.2
0.33

[0046]
Table 2 d) Layer deposition conditions Film forming temperature Processing solution concentration d) Layer appearance
(℃) (mol/liter)
−−−−−−−−−−−−−−−−−−−−−−−−
−−−−−−−−−−−−−−−−−−−−−−−−−
−−−−−−− Comparative example 7 30
2.5 Partial cloudiness
Comparative example 8 30
3.0 Cloudy, uneven
Comparative example 9 30 4.0
Unable to form film

It is clear that it is possible to form a dense silicon dioxide film on the surface of the plastic molded article.

Examples 7 to 9 A 100 nm silicon dioxide film was formed on a polycarbonate plate on which layers b) and c) were formed in exactly the same manner as in Examples 4 to 6, using the conditions of each deposition method shown in Table 3. (d)
layer) was formed. A transparent silicon dioxide coating (layer d) having a uniform thickness was formed on the polycarbonate flat plate. This means that a silicon dioxide film having a thickness of about 120 nm in total from layers c) and d) was obtained on the polycarbonate substrate.

Both of the silicon dioxide coatings (layer c) and layer d) had such strong adhesion that they did not peel off at all in a test in which cellophane adhesive tape was applied and peeled off. In addition, even though it was immersed in boiling water for 1 hour, there was no change in adhesive strength. Each of the obtained polycarbonate flat plates was placed in a hot air dryer at a predetermined temperature (85 to 100°C) and taken out after 2 hours, and the presence or absence of cracks was examined. The results are shown in Table 3. The ○ mark in the table means "no cracks", and the X mark "
Each indicates that cracks occur.

Comparative Example 10 A 120 nm thick layer c) was formed on a polycarbonate flat plate on which the layer b) had been formed in exactly the same manner as in Examples 7 to 9, under the same conditions as in Examples 7 to 9. The obtained polycarbonate flat plate was placed in a hot air dryer at a predetermined temperature and taken out after 2 hours, and the presence or absence of cracks was examined. The results are shown in Table 3.

From Table 3, it can be seen that in Examples 7 to 9, cracks are less likely to occur in the silicon dioxide coatings at high temperatures than in Comparative Example 10, and this tendency is greater as the film forming temperature is higher.

[0052]
Table 3 Precipitation method conditions Crack generation temperature Film forming temperature Treatment liquid concentration 85℃ 90℃ 95℃ 10
0℃ (℃) (mol/
liter) −−−−−−−−−−−−−−−−
−−−−−−−−−−−−−−−−−−−−−−−−−
−−−−−−−−−−−−−−−−−−−−−−−−−
--- Example 7 30
2.5 ○
X X Example 8 35
2.5 ○
○ X X Example 9
40 2.5 ○
○ ○ X Example 1
0 −−−−− −−−−−−−
X X X
X

[0053]
Table 4 d) Layer deposition conditions Film forming temperature Processing solution concentration d) Layer appearance
(℃) (mol/liter)
−−−−−−−−−−−−−−−−−−−−−−−−
−−−−−−−−−−−−−−−−−−−−−−−−−
------- Comparative example 11 30
2.5 Partial cloudiness
Comparative example 12 35
2.5 Cloudy, uneven Comparative example 13 40 2.5
Unable to form film

Comparative Examples 11-13 An attempt was made to form the d) layer directly on the b) layer in exactly the same manner as in Examples 7 to 9 except that the c) layer was not formed. The results are shown in Table 4. From the results in Table 4, it can be seen that unless layer c) is formed, it becomes more difficult to obtain a silicon dioxide film as the film is formed at a higher temperature. That is, from the results of Examples 7 to 9 and Comparative Examples 11 to 13, c)
It is clear that the formation of the layer makes it possible to form a silicon dioxide coating on the surface of the plastic molded article that is less likely to cause cracks.

[0055]

Effects of the Invention As detailed above, the method for manufacturing a silicon dioxide coated body of the present invention is to form a layer formed by coating and curing a hydrolyzable organosilane with good adhesion on the surface of a plastic molded body or other substrate in advance. Then, a silicon dioxide coating (c) layer) is applied by a precipitation method under conditions that allow a transparent film with a uniform thickness to be obtained, and then a silicon dioxide coating (d) layer) is applied by a precipitation method.
c) Under all conditions of the precipitation method, such as increasing the silicon concentration in the treatment solution and increasing the temperature, in order to obtain a dense silicon dioxide film by forming a layer,
It has become possible to obtain on the substrate surface a transparent silicon dioxide coating (layer d) which is transparent, has excellent thickness uniformity, has high gas barrier properties and water absorption prevention properties, and is less likely to crack at high temperatures.

[Brief explanation of the drawing]

FIG. 1 is a system explanatory diagram of a silicon dioxide film manufacturing apparatus used to carry out the present invention.

[Explanation of symbols]

1...Outer tank 2...Inner tank 3...Water 4...Heater 5...Agitator 6...Inner tank front 7...Inner tank middle 8...Inner tank rear 9...Cleaning liquid tank
10...5% HF aqueous solution 11...Filter 12...Circulation pump 13...Three-way cock
14...Base

Claims (7)

[Claims] Claim 1: a) a substrate; b) a layer formed by coating and curing at least one silicon compound selected from the group consisting of organosilanes, their hydrolysates, and colloidal silica; c) supersaturated silicon dioxide; a layer of a silicon dioxide film formed by contacting the aqueous solution of hydrosilicofluoric acid (a) with a predetermined silicon concentration in a state of A layer of a silicon dioxide film formed by contacting the layer c) with an aqueous silicofluoric acid solution (b) having a silicon concentration higher than that of the aqueous hydrofluoric acid solution (a), a), b) , c) and d) are laminated in this order. 2. The hydrosilicofluoric acid aqueous solution (a) is 2.
The silicon dioxide coated body according to claim 1, wherein the silicon dioxide-coated body has a silicon concentration of 0 mol/liter or less, and the hydrosilicofluoric acid aqueous solution (b) has a silicon concentration of 2.5 mol/liter or more. [Claim 3] The organosilane has the following general formula (1
) The silicon dioxide coated body according to claim 1, which is a silicon compound represented by: R1nSi(R2)4-n (1) (wherein R1 is a hydrocarbon group having 1 to 6 carbon atoms, a vinyl group, a methacryloxy group, an amino group, a mercapto group, an epoxy group, or an organic group having fluorine or chlorine. , R2
is an alkoxy group, an alkoxyalkoxy group, an acetoxy group, or a chlorine element, and n is an integer of 0 to 2. ) 4. The silicon dioxide coated body according to claim 1, wherein the base body is a plastic molded body. Claim 5: a) on the surface of the substrate, b) the following general formula (1):
R1nSi(R2)4-n (1) (wherein R1 is a hydrocarbon group having 1 to 6 carbon atoms, a vinyl group, a methacryloxy group, an amino group, a mercapto group, an epoxy group, or an organic group having fluorine or chlorine. , R2
is an alkoxy group, an alkoxyalkoxy group, an acetoxy group, or a chlorine element, and n is an integer of 0 to 2. )
c) At least one silicon compound selected from the group consisting of silicon compounds represented by the formula, their hydrolysates, and colloidal silica is coated and cured, and c) silicon dioxide is supersaturated and the silicon concentration is 2.0 mol/ liter or less of the hydrosilicofluoric acid aqueous solution in b) above.
contacting the layer and forming a silicon dioxide coating thereon; d
) Furthermore, silicon dioxide is in a supersaturated state and the silicon concentration is 2.
A method for producing a silicon dioxide-coated substrate, which comprises contacting the layer c) with an aqueous solution of hydrosilicofluoric acid having a concentration of 5 mol/liter or more to form a silicon dioxide coating on the layer c). 6. The silicon concentration of the hydrosilicofluoric acid aqueous solution (b) is 0.6 to 0.6 to
The silicon dioxide-coated substrate according to claim 1, which has a high content of 2.5 mol/liter. 7. Claim 1, wherein the contact temperature of the aqueous solution of hydrosilicofluoric acid (a) is 30° C. or lower, and the contact temperature of the aqueous solution of hydrosilicic acid (b) is 25° C. or higher. The silicon dioxide-coated substrate described in Section 1.