JPH01101339A - Production of silicon dioxide-coated acrylic resin form - Google Patents

Abstract

PURPOSE:To obtain the titled form of high durability, coated with uniform film, by coating and curing a specific organosilicon compound on an acrylic resin form to make the primary coating film followed by contact with a silicon dioxide-supersaturated hydrosilicofluoric acid solution. CONSTITUTION:A mixture of (i) a silicon compound of formula I [R<1> is methacryloxy group-carrying organic group; R<2> is (alkoxy)alkoxy, acetoxy or Cl] and (ii) a hydrolyzate from a second silicon compound of formula II (R<3> is the same as R<2>) so that the ratio to R<1>SiO3/2-reduced weight A for the component (i) of SiO2-reduced weight B for the component (ii) satisfy the relationship: 0.1<B/A<0.5 is coated on an acrylic resin form followed by curing to make the primary film. The resulting acrylic resin form is brought into contact with (iii) a silicon dioxide-supersaturated hydrosilicofluoric acid solution to form a silicon dioxide film on said primary film, thus obtaining the objective form.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for producing a silicon dioxide-coated acrylic resin molded body, and particularly to acrylic resin molding such as an acrylic disk for an optical disk substrate having fine irregularities on the surface. The present invention relates to a method for producing a silicon dioxide film that can maintain the surface irregularities and form a highly durable and uniformly thick silicon dioxide film on a body surface.

[Prior Art] Transparency is required for substrates using light-based memory materials. Glass or transparent plastic is likely to be used as the transparent disc material. Glass and plastic as disc materials each have their own advantages and disadvantages, making material selection difficult.
Plastic is considered superior in terms of manufacturing costs.

However, since plastics such as PMMA and PC have good air permeability and water permeability, they may cause warping, or when used as a disk substrate, zero particles may enter from the back side of the substrate.
2. H20 diffuses into the recording film layer, resulting in performance deterioration due to oxidation of the recording layer. Therefore, in order to prevent this, Si3Na, Sin,
A process is performed to provide a base film such as 5i02. These base films are usually formed by vacuum methods such as vapor deposition and sputtering.

On the other hand, as a method for producing a silicon dioxide film, in addition to these methods such as vapor deposition and sputtering, a silicon dioxide film is formed on the surface of the base material by immersing the base material in a hydrosilicofluoric acid solution that is supersaturated with silicon dioxide. A method for forming the oxide (hereinafter abbreviated as "precipitation method") is known (for example, Japanese Patent Application Laid-Open No. 62-20876).
.

In particular, regarding the method of forming a silicon dioxide coating on a plastic molded body by a precipitation method, the plastic molded body is coated with silicon compounds such as organic silicon compounds, their hydrolysates, and colloidal silica and cured to form a primary coating. After that, a method is known in which a silicon dioxide film is formed on the primary film by a precipitation method (for example, Japanese Patent Application Laid-Open No. 61-1273).
4).

[Problems to be solved by the invention] When forming a silicon dioxide film on the surface of a plastic molded body by conventional vacuum methods such as vapor deposition and sputtering, ■ gas is generated from the substrate during film formation, resulting in a high quality film. is difficult to obtain.

(2) It is difficult to form a film that follows the uneven shape of tracking grooves formed on the surface of an optical disk substrate, grating lens, etc.

■ The obtained film has poor adhesion to the resin substrate and is easily peeled off due to temperature and humidity loads.

On the other hand, the deposition method allows film formation at a lower temperature than the vacuum method.

■ Uniform film formation on irregularly shaped surfaces is possible.

When such effects are achieved and the base film of the optical disk substrate is limited to a silicon dioxide film, it is expected that the problems of the above-mentioned sputtering or vapor deposition methods can be solved to some extent.

However, the primary film obtained by coating and curing silicon compounds such as organosilicon compounds, their hydrolysates, and colloidal silica on plastic substrates with fine irregularities such as front disk substrates and grating lenses,
Since the film thickness tends to be as thick as 0.5 to 30 μm, the irregularities on the substrate surface are likely to disappear, and even if silicon dioxide is coated on the primary film by a precipitation method, optical disk substrates and gratings that are suitable for practical use. There was a problem that lenses etc. could not be created.

[Means and effects for solving the problems] The present invention solves the above-mentioned conventional problems and provides a plastic molded product, especially an acrylic resin molded product, which can maintain surface irregularities and has excellent durability. A method of producing a silicon dioxide coating of uniform thickness is provided.

In the present invention, an acrylic resin molded body is coated with an organosilicon compound and cured to form a primary coating, and then the acrylic resin molded body with the primary coating is treated with a supersaturated hydrosilicofluoric acid solution of silicon dioxide. A method for producing a silicon dioxide-coated acrylic resin molded article, in which a silicon dioxide coating is formed on a primary coating by contacting the silicon compound with a methacryloxy group represented by the general formula (r); R'SiO3/2 of a silicon compound having a methacryloxy group represented by the general formula (1)
The ratio of the converted weight (A) to the Stow converted weight (B) of the silicon compound represented by formula (II) is 0.1<B/A
The gist of the present invention is a method for producing a silicon dioxide-coated acrylic resin molded article, which is formed by coating and curing a mixture containing a silicon dioxide-coated acrylic resin molded article in such a manner that the acrylic resin molded article is less than 0.5.

R' St (R')3...(ri5
i(R3)4...-(TI) (in the formula,
R1 is an organic group having a methacryloxy group, and R2 and R3 are one or more bonding groups selected from an alkoxy group, an alkoxyalkoxy group, an acetoxy group, and a chlorine element. ) When directly coating the surface of a plastic molded object with a silicon dioxide film using the precipitation method, the reactivity and wettability of the hydrosilicofluoric acid solution and the plastic are poor, resulting in weak adhesion and uneven film formation. However, if the plastic molded body is coated with an organosilicon compound and cured in advance, the silanol groups on the surface will become a place for bonding with the silicon component in the hydrosilicofluoric acid solution. It is possible to improve the adhesion and unevenness of the film.

However, the first method obtained by coating and curing an organosilicon compound
When the thickness of the subsequent coating is reduced to several hundred angstroms or less, the deposition method is used to create an even and uniform film.
In order to obtain a silicon dioxide film with strong adhesion, it is necessary to select an organic silicon compound depending on the type of plastic.

As a result of extensive research into organosilicon compounds suitable for forming primary coatings on acrylic resin molded bodies, the present inventors have discovered a silicon compound having a methacryloxy group represented by the general formula (1) above. The present invention has been completed based on the discovery that a mixed system of a hydrolyzate of a silicon compound represented by the general formula (TI) in a specific ratio is optimal.

The present invention will be explained in detail below.

In the present invention, among the silicon compounds used to form the primary film, γ-methacryloxypropyltrimethoxysilane is preferable as the silicon compound having a methacryloxy group represented by the general formula (I). Also, the general formula (
Examples of the silicon compound represented by II) include tetraethoxysilane, and its hydrolyzate is a silicon compound in which part or all of the alkoxy group, alkoxyalkoxy group, acyloxy group, or chlorine element is substituted with a hydroxyl group. It also includes those in which substituted hydroxyl groups are partially naturally condensed. These hydrolysates can be easily obtained, for example, by hydrolysis in a mixed solvent such as water and alcohol in the presence of an acid.

As the silicon compound having a methacryloxy group represented by the general formula (I), one type may be used alone or two or more types may be used in combination. Similarly, with respect to the silicon compound represented by the general formula (TI), 1 fm may be used alone or two or more types may be used in combination.

In the present invention, the mixing ratio of the silicon compound having a methacryloxy group represented by the general formula (I) and the hydrolyzate of the silicon compound represented by the general formula (II) is as follows:
R' of a silicon compound having a methacryloxy group represented by
S i 03/2 equivalent weight ff1(A) and the general formula (I
The ratio of the silicon compound represented by I) to the 5in2 equivalent weight (B) is set to be 0.1 and B/A<0.5.

The adhesion of the silicon dioxide coating obtained by the precipitation method is largely controlled by the average molecular weight of the acrylic resin of the acrylic resin molding forming the coating and the mixing ratio B/A of the silicon compound.

In the present invention, in order to obtain a silicon dioxide coating with strong adhesion, the average molecular weight of the acrylic resin substrate used is 8.
The above B/A ratio is preferably 0.1<B/
It needs to be A.

As a method for coating and curing such a mixture of silicon compounds on an acrylic resin molded body to form a primary film, a dip coating method using a coating solution prepared by dissolving the mixture of silicon compounds in various solvents is suitable. .

The primary coating to be formed can be applied to a glass substrate (for example, ordinary plate glass,
When a film is formed under similar conditions on (soda lime glass, etc.), the film can be formed under conditions such that a film with a thickness of 5 to 50 nm, preferably 10 to 30 nm, is created. desirable.

That is, if the primary coating is formed under conditions such that a coating with a thickness of up to about 50 nm is formed on a glass substrate, a coating that maintains the surface unevenness of the optical disk substrate can be obtained. If the primary film is created on a glass substrate under conditions where it becomes thicker than 50 nm, shape followability may deteriorate. Also, the film thickness was 5n on the glass substrate.
Conditions where the thickness is less than m are not suitable because this will result in a decrease in the adhesion strength of the silicon dioxide film obtained by the precipitation method.

In the present invention, in order to form a primary film having such a thickness, it is preferable that the silicon compound concentration in the coating liquid is 0.5 to 3% by weight.

As mentioned above, the conditions for forming the thickness of the primary coating are expressed using the glass substrate as a monitor when directly measuring the thickness of the primary coating on the acrylic resin substrate. The smoothness of the film is poor, making it difficult to measure the film thickness with a contact needle film thickness measuring device.

■ Because the silicon compound applied to the acrylic resin substrate gradually diffuses into the interior of the acrylic resin substrate, the interface between the acrylic resin substrate and the silicon compound is unclear, making it impossible to measure the film thickness by observation using an electron microscope, etc. It is.

This is because there are two problems.・In this way, the primary film created on the acrylic resin substrate has a film thickness below a certain level because the silicon compound having a methacryloxy group represented by the general formula (I-) penetrates into the inside of the acrylic resin substrate. If so, the shape of the optical disk substrate can be maintained. However, since the hydrolyzate of the silicon compound represented by general formula (II) is difficult to penetrate into the inside of the acrylic resin substrate,
If the mixing ratio (B/A) to the silicon compound having a methacryloxy group becomes high, the surface shape of the optical disk substrate will be damaged. Therefore, in the present invention, the mixing ratio B/A is set to B/A minus 0.5. “In the present invention, the acrylic resin substrate on which the primary film has been formed is then brought into contact with a supersaturated hydrosilicofluoric acid solution of silicon dioxide to form a silicon dioxide film on the primary film.

A supersaturated silicofluoric acid solution of silicon dioxide (hereinafter referred to as “
It is abbreviated as "processing liquid". ), silicon dioxide (silica gel, aerogel, silica glass,
Other silicon dioxide-containing substances) are dissolved in water or reagents (boric acid, aluminum chloride, metallic aluminum,
A supersaturated state of silicon dioxide is used, for example, by adding a solution (other than others) or increasing the temperature of the processing solution.

In the present invention, the concentration of hydrosilicofluoric acid in the treatment liquid that is brought into contact with the substrate of the acrylic resin molded body with the primary coating is preferably 1 to 3 mol/It, particularly silicofluoric acid that is higher than 3 mol/It. After saturating silicon dioxide in an aqueous solution of hydrohydric acid,
It is preferable to dilute it with water to a concentration of 1 to 3 mol/L because the film formation rate is fast and the film can be formed efficiently.

In addition, the treatment liquid (a) also contains (a) an aqueous solution of additives such as boric acid, chloride/aluminum chloride, etc. that is continuously added and mixed during contact with the molded body, and (i) metals such as aluminum are dissolved and mixed. ■It is a processing liquid in which the degree of supersaturation is maintained at all times by means such as temporarily cooling the temperature to saturate silicon dioxide, and then raising the temperature again, and (b) the total amount of processing liquid per minute. It is preferable that 3% or more of the treatment liquid is the treatment liquid that is filtered through a filter and returned.

At the time of contact, it is preferable to (1) continuously add and mix an aqueous solution such as boric acid or (2) dissolve and mix a metal such as aluminum in order to improve the rate of film formation.

In the case of boric acid, the amount added is 1 part of hydrosilicic acid in the processing solution.
5X10-'mol/Hr"'1.0xlO per mole
-' mol/Hr is preferable, and when metallic aluminum is dissolved, the amount dissolved is lXl0-' mol/hr to 1 mol of fluorosilicic acid/hydrogen acid in the treatment solution.
A range of 4X10-3 mol/hr is preferred.

Circulating the treatment liquid at a concentration of 3% or more is effective for continuously obtaining a homogeneous coating, and filtering the treatment liquid with a filter is preferable for obtaining a coating without irregularities.

When the treatment liquid is placed in a dipping tank and brought into contact with the molded body, it is necessary to allow the treatment liquid to flow in a laminar flow on the surface of the molded body during immersion in order to obtain an even and homogeneous coating. effective.

Note that the silicon dioxide film obtained by such a precipitation method contains adsorbed water and silanol groups, and in order to remove these, it is preferable to subject the film to heat treatment using high frequency waves or the like.

[Examples] Hereinafter, the present invention will be described in detail 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 γ-methacryloxypropyltrimethoxysilane 1.5
A mixture of 3 g of C3GL-0803P (manufactured by Chisso ■, solid content concentration 8% (hydrolyzate of tetraethoxysilane)) (B/A = 0.22) was mixed with ethanol: isopropyl alcohol: n-butyl alcohol = 5: A solution (silicon compound concentration: 0.9% by weight) dissolved in 250 mA of a mixed solvent of 3:2 (volume ratio) was coated with a 100 mm length and width and a thickness of 1.5 mm.
5mm acrylic resin flat plate (extruded plate, number average molecular weight 57
000) was immersed, pulled up at a speed of 15 cm/min, and then left at room temperature for 1 hour. - When a primary film was formed on a glass substrate under exactly the same conditions as the above operation, the film thickness was approximately 1 nm.

A silicon dioxide film was formed on the obtained primary coated acrylic flat plate using the silicon dioxide film manufacturing apparatus shown in FIG.

In FIG. 1, the dipping tank consists of an outer tank 1 and an inner tank 2, and the space between the inner tank 2 and the outer tank 1 is filled with water 3. This water is heated by a heater 4 to a temperature of 40° C., and is stirred to make the temperature distribution uniform. The inner tank 2 consists of a front part 6, a middle part 7, and a rear part 8, and each part has industrial silica gel powder used as a source of silicon dioxide to dissolve and dissolve silicon dioxide.
Saturated 2.5 mou/41 aqueous solution of hydrosilicofluoric acid 6
．． 5j2 is satisfied.

Using such a device, first, the circulation pump 10 was 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 11, and start circulating the treated liquid back to the front part 6 of the inner tank.

After that, AJ2 plate 123 with length and width of 50 mm and thickness of 3 mm
The sheet was immersed in the rear part 8 of the inner tank and held for 10 hours. In this state, the reaction solution became a treatment solution having appropriate levels of Sin and supersaturation. Here, the absolute removal rate of filter 11 is 1.5 μm.
, processing liquid circulation flow rate is 520mj! /m1n (The total volume of processing liquid is approximately 6.5ft, so the circulation flow rate is 8%/m1n.
n). Then, the acrylic flat plate 9 on which the primary coating was formed with the silicon compound was immersed vertically into the inner tank middle part 7, and the conditions were as described above (i.e., 8%/min circulation with the three AIL plates immersed). 1.5μ
(filtered with a filter of 500 ml) for 120 minutes.

The thickness of the silicon dioxide film obtained by the above treatment is approximately 110
It was 0n. This film-forming part is
on 5pectroscopy for Chem
As a result of analysis using ical analysis), it was confirmed that most of the material consisted of 5i02.

The obtained silicon dioxide film had a strong adhesion that could not be peeled off at all in a test in which a cellophane adhesive tape was attached and peeled off. Further, the acrylic resin substrate with the silicon dioxide coating was immersed in boiling water for 1 hour, but there was no change in the adhesion of the coating.

Comparative Example 1 2 g of γ-methacryloxypropyltrimethoxysilane was added to 250 ml of a mixed solvent of ethanol: isopropyl alcohol: n-butyl alcohol = 5:3:2 (volume ratio).
．． 100mm in length and width and 1.5m in thickness.
m acrylic flat plate (extruded plate, number average molecular weight 57,000)
was immersed, pulled up at a speed of 15 cm/min, and then left at room temperature for 1 hour.

A silicon dioxide film (100 nm) was formed on this primary coated acrylic flat plate in the same manner as in Example 1.

The obtained silicon dioxide coating was cloudy and uneven, and as a result of electron microscopic observation, it was found that silicon dioxide was sparsely attached in the form of particles.

Example 2.3, Comparative Examples 2 and 3 The following four types of acrylic flat plates (extruded plates, number average molecular weight 57,000) each having a diameter of 60 mm and a thickness of 1.5 mm were prepared.

(i) A silicon dioxide wave 11i (50 parts m thick) formed by the same process as in Example 1 (Example (ii)
A silicon dioxide film (10
0 nm thick) (Example 3) (iii) Silicon dioxide waves 11i (100 nm thick) were formed on both the front and back surfaces by sputtering (Comparative Example 2) (iv) Untreated (Comparative Example 3) Table 1 shows the results of measuring the moisture permeability of these materials according to JIS Z-0208 (40° C., 90% RH).

As is clear from Table 1, the silicon dioxide film formed by the precipitation method has a sufficient effect of blocking water vapor, and the effect was found to be greater than that of the silicon dioxide film formed by the sputtering method.

Table 1 Comparative Example 4 (see Example 3 of JP-A-61-12734)
207 parts of methyltrimethoxysilane, 341 parts of colloidal silica (manufactured by Yasan Kagaku Kogyo Co., Ltd., trade name Snowtex C0 solid content 20%) and 6 parts of acetic acid were mixed, and after stirring with an external cooler for 1 hour, the mixture was heated to room temperature. I left it for a day. To 160 parts of the hydrolyzate solution thus obtained were added 30 parts of ethyl cellosolve, 0.5 parts of ammonium chloride, and a small amount of a flow control agent to prepare a paint.

Pre-cleaned acrylic substrate (length 100mm.

Apply the above paint to a width of 100 mm and a thickness of 1.4 mm,
It was dried and cured by heating at 90° C. for 3 hours in a hot air drying oven.

A primary film with a thickness of approximately 5 μm was formed on the acrylic substrate.

Comparative Example 5 In Comparative Example 4, in order to form a primary film of several hundred angstroms on an acrylic substrate, ethyl alcohol: isopropyl alcohol: n-butyl alcohol = 5:3 was added to 4 parts of a hydrolyzate solution of methyltrimethoxysilane. :
, 2 (volume ratio), ammonium chloride, and a small amount of a flow control agent were added to prepare a coating liquid.

, an acrylic flat plate with length and width of 100 mm and thickness of 1.5 mm (
The coating solution was applied to an extruded plate (number average molecular weight: 57,000), and dried and cured by heating at 80° C. for 3 hours in a hot air drying oven. When a primary film was formed on a glass substrate under the same conditions as the above operation, the film thickness was approximately 10 parts m.

Thereafter, a silicon dioxide film (150 nm) was formed on the obtained acrylic substrate with the primary film in the same manner as in Example 1 using a silicon dioxide supersaturated solution of hydrosilicofluoric acid.

The resulting silicon dioxide coating had poor adhesion and was easily peeled off in a test in which cellophane adhesive tape was applied and peeled off.

[Effects of the Invention] As described in detail above, the method for producing a silicon dioxide-coated acrylic resin molded article of the present invention provides a method for producing a silicon dioxide-coated acrylic resin molded article by applying a methacrylic resin represented by the general formula (I) on the surface of the acrylic resin molded article.

By coating and curing a mixture containing a silicon compound having a roxy group and a hydrolyzate of the silicon compound represented by the general formula (II) in a specific ratio, a very thin silicon-containing coating with good adhesion is formed. According to the method of the present invention, the silicon dioxide film is coated as a primary film, and then a silicon dioxide film with good adhesion to the 10th film is formed on top of the first film. It is possible to form a coating that is much more durable than a silicon dioxide coating formed on the body surface.

■ In the coating method for forming the primary film, a dilute solution of a silicon compound can be used as the coating liquid, and furthermore, the silicon compound diffuses into the acrylic resin, so the optical disk substrate has a fine uneven shape. It is possible to coat the surface with a thin film without damaging its shape.

(2) After the primary coating is formed, silicon dioxide is precipitated into a film by contacting with a solution, so it is possible to form a silicon dioxide coating that follows the uneven shape of the surface of an acrylic resin optical disk substrate, etc.

■ Films can be formed on both the front and back surfaces at the same time, and the resulting silicon dioxide film not only has the effect of blocking the transmission of water vapor, oxygen, etc., but also has the effect of improving the wear resistance of the laser incident side surface of the optical disc. It is also equipped with

Excellent effects such as these can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a system explanatory diagram of the silicon dioxide film manufacturing apparatus used in the examples. 1...Outer tank, 2...Inner tank, 3...Water, 4...Heater, 5...
... Stirrer, 6... Inner tank front, 7...
Middle part of inner tank, 8... Rear part of inner tank, 9... Acrylic resin molded body, 10... Circulation pump, 11... Filter,
12... Metal aluminum plate, 13... Stirrer. Agent Patent Attorney Tsuyoshi Shigeno

Claims (4)

[Claims] (1) After coating an acrylic resin molded body with an organosilicon compound and curing it to form a primary coating, the acrylic resin molded body with the primary coating is brought into contact with a supersaturated hydrosilicofluoric acid solution of silicon dioxide. In the method for producing a silicon dioxide-coated acrylic resin molded article, the primary coating comprises a silicon compound having a methacryloxy group represented by the general formula (I) and a silicon dioxide coating formed on the primary coating by forming a silicon dioxide coating on the primary coating. (II) and the hydrolyzate of the silicon compound represented by the general formula (I).
R^ of a silicon compound having a methacryloxy group represented by
1SiO_3_/_2 equivalent weight (A) and general formula (II)
A silicon dioxide-coated acrylic product, characterized in that it is formed by coating and curing a mixture containing a silicon compound represented by the formula in such a manner that the ratio of the silicon compound to the SiO_2 equivalent weight (B) is 0.1<B/A<0.5. A method for producing a resin molded body. R^1Si(R^2)_3...(I) Si(R^3)_4...(II) (In the formula, R^1 is an organic group having a methacryloxy group, and R^2 and R ^3 is 1 selected from alkoxy group, alkoxyalkoxy group, acetoxy group, and chlorine element
A species or a plurality of linking groups. ) (2) The method for producing a silicon dioxide-coated acrylic resin molded article according to claim 1, wherein the acrylic resin molded article has a number average molecular weight of 80,000 or less. (3) Claim 1, wherein the conditions for creating the first film are such that a film with a thickness of 5 to 50 nm is created when the film is created on a glass substrate under similar conditions. Or the method for producing a silicon dioxide-coated acrylic resin molded article according to item 2. (4) The primary film is formed by applying a coating liquid containing 0.5 to 3% by weight of a silicon compound and drying the coating according to any one of claims 1 to 3. A method for producing a silicon dioxide-coated acrylic resin molded article.