JPH091046A - Manufacture of laminate - Google Patents

Abstract

PURPOSE: To easily manufacture a laminate in which a coat having the high stability of optical properties such as a refractive index is laminated on a backing of poor heat resistance by applying a metal alkoxide type paint on the backing and placing the laminate in an environment of relative humidity of a specified value or less. CONSTITUTION: This process for manufacturing a laminate is a process in which a metal alkoxide type paint is applied on a backing, and the product is placed in an environment of 70% or more relative humidity. In this process, the treatment temperature is not limited in particular. However, since the treatment requires a long time at a lower temperature, while the deformation of the backing of an organic material is caused at a higher temperature, the preferable temperature is 40-100 deg.C. With regard to the treatment time, which depends on relative humidity, an effect for removing residual unreacted groups is not obtained when it is short, and the effect corresponding to its length is not obtained when it is too long, so that 50-1200hr is usually preferable. By placing the product in the above environment, the hydrolysis of the residual alkoxy group in the coat and the polycondensation of the residual hydroxyl group are accelerated, stabilizing the structure of fine particles which form the coat.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminate in which a coating film made of a cured product of a metal alkoxide paint is laminated on a substrate. In particular, the present invention relates to a laminate in which a coating having a high stability of optical properties such as a refractive index is laminated on a base material having low heat resistance, which is a cured product obtained by curing a metal alkoxide-based coating material at a low temperature.

[0002]

2. Description of the Related Art In recent years, transparent plastic materials have been widely used for liquid crystal display devices, optical lenses, spectacle lenses, windows of buildings, etc. in place of glass, taking advantage of their characteristics of light weight, easy workability and impact resistance. However, many of these materials have a high refractive index, and external rays are reflected, causing optical obstacles due to reflection.

The reason why the transparent plastics material reflects an external light ray is that when light is incident on the transparent plastics material from the air, the reflection of the light at the interface is caused by the difference in the refractive index between the air and the transparent plastics material. Because it will happen.

In order to reduce the above-mentioned reflection of light, there has been a method of laminating thin films having different refractive indexes on a transparent plastic material by using a vacuum deposition method, an ion plating method, a sputtering method or the like. This method has advantages such as film thickness control and antireflection effect in a wide wavelength range. However, when manufacturing a thin film, it is necessary to manufacture the thin film in a limited space. Not suitable for
There is a problem that it is industrially unsuitable from the viewpoint of cost and cannot be applied to a base material having a complicated shape.

As another method, there has been a method of laminating thin films having various refractive indexes on a transparent plastic material using a metal alkoxide paint. This method is based on a technique called a sol-gel method. This method is advantageous in terms of cost because continuous production is possible, and since it has shape compatibility, it can be applied to a substrate having a complicated shape. Can also provide antireflection performance. This metal alkoxide-based paint is obtained by adding a solvent and water to the metal alkoxide, and through the hydrolysis and polycondensation process of the alkoxy group. An inorganic coating is obtained. However, in order to stabilize the optical properties such as the refractive index of this inorganic coating, it is necessary to remove residual alkoxy groups, residual hydroxyl groups, residual solvent and residual water to the utmost limit. For this purpose, the thermosetting temperature needs to be several hundreds of degrees Celsius or higher, and there is a problem that it is difficult to apply it to a substrate having low heat resistance. Therefore, when the curing temperature is lowered, for example, when an organoalkoxysilane-based coating material is applied onto a resin base material and cured at about 80 ° C., the obtained laminate is subjected to a high humidity environment or a thermal shock environment. When left in a harsh environment such as, there is a problem that the refractive index of the coating changes with time and the antireflection performance is not stable.

[0006] As a known technique that may be used to solve the above problems, a catalyst for silicone polymerization or the like may be added to improve the reactivity of the organoalkoxysilane in the paint (Japanese Patent Laid-Open No. 3-31380). Publication, JP-A-3-
52977), it is conceivable to increase the molecular weight of the organoalkoxysilane in the paint and decrease the amount of silanol groups remaining in the molecule.

However, when the reactivity at room temperature is improved by these methods, the storage stability of the paint is lowered,
Pot life may be shortened. Further, even coatings obtained by using these techniques have insufficient optical stability at a curing temperature of around 100 ° C.

[0008]

SUMMARY OF THE INVENTION The present invention is intended to solve these problems, and an object thereof is to provide a base material having low heat resistance with a cured product of a metal alkoxide-based coating material such as a refractive index. It is an object of the present invention to provide a method capable of easily producing a laminated body in which a coating having high stability of optical properties is laminated.

[0009]

The metal alkoxide-based paint referred to in the present invention is a paint obtained by hydrolyzing and polycondensing a metal alkoxide represented by the following general formula (1) in an organic solvent such as alcohol. It is a thing. R _n M (OR ¹ ) _m (1) In the formula, R is an organic group represented by an alkyl group, R ¹ is an alkyl group, and M is a metal atom. Although n and m are natural numbers, the sum of n and m is equal to the valence of the metal atom M.

Examples of the metal alkoxide include alkoxysilane represented by the following general formula (2) and alkoxytitanium represented by the following general formula (3). During ^{_{R n Si (OR 1) m}} ··· (2) Ti (OR 1) 4 ··· (3) formula, R, R ^1, n and m are the same as above.

As the above-mentioned alkoxysilane, for example,
Tetramethoxysilane, tetraethoxysilane, tetra-n-propoxysilane, tetra-iso-propoxysilane, tetra-n-butoxysilane, tetra-sec
-Butoxysilane, tetra-tert-butoxysilane, monomethyltrimethoxysilane, monomethyltriethoxysilane, monomethyltri-n-propoxysilane, monomethyltri-iso-propoxysilane, monomethyltri-n-butoxysilane, monomethyltri-s
ec-butoxysilane, monomethyltri-tert-butoxysilane, ethyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyldi-n-propoxysilane, dimethyldi-iso-propoxysilane, dimethyldi-n-butoxysilane, dimethyldi- sec-butoxysilane, dimethyl di-ter
t-butoxysilane, diethyldiethoxysilane, trimethylmonomethoxysilane, trimethylmonoethoxysilane, trimethylmono-n-propoxysilane, trimethylmono-iso-propoxysilane, trimethylmono-n-butoxysilane, trimethylmono-sec-butoxy Examples thereof include silane, trimethylmono-tert-butoxysilane, and triethylethoxysilane. From the viewpoint of reactivity of hydrolysis and polycondensation, tetramethoxysilane, tetraethoxysilane, and monomethyltriethoxysilane are preferable, and tetraethoxysilane is particularly preferable. Used.

As the above-mentioned alkoxy titanium, tetra-
Iso-propoxy titanium, tetra-n-butoxy titanium and the like are preferably used from the viewpoint of reactivity of hydrolysis and polycondensation.

As a method for curing the metal alkoxide-based paint, heat curing is generally used. For example, the curing process of the alkoxysilane represented by the formula (2) is schematically shown below.

[0014]

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That is, when an alkoxysilane-based coating material is applied to a substrate and heat-cured, a silica coating film is obtained through the above reaction process. However, this silica coating is a porous body having fine pores, and since it has many unreacted residual groups, in order to stabilize its optical properties, residual alkoxy groups, residual hydroxyl groups, residual solvents, It is necessary to remove residual water to the limit. For this reason, the present invention is characterized by placing in an environment with a relative humidity of 70% or more instead of heat curing.

In the present invention, the environment with a relative humidity of 70% or more is preferably an environment with a relative humidity of 80% or more, more preferably a relative humidity of 95% or more. If the relative humidity is less than 70%, the effect of removing residual unreacted groups and the like cannot be obtained.

The temperature when placed in an environment having a relative humidity of 70% or more is not particularly limited, but when the temperature is low, the treatment takes time, and when the temperature is high, the organic base material is deformed. Since it easily occurs, 40 to 100 ° C
Is preferable, and 50-90 degreeC is especially preferable.

Although the time for placing in the environment with the relative humidity of 70% or more depends on the relative humidity, if the time becomes short,
Since the effect of removing the residual unreacted groups cannot be obtained, and the effect corresponding to the time cannot be obtained even if the time is too long, it is usually 5
0 to 1200 hours are preferable, and 100 to 1000 hours are more preferable.

Further, it is preferable to carry out an appropriate heat treatment at a deformation temperature of the substrate or lower after the substrate is placed in the high humidity environment because the adhesion between the coating and the substrate is improved.

The base material used in the present invention is not particularly limited as long as it is a base material to which a metal alkoxide paint can be applied, and examples thereof include polycarbonate, acrylic resin, polyvinyl chloride, polystyrene, polyester, polyurethane, Organic substrate made of polyethylene terephthalate, cellulose triacetate, etc .; inorganic made of silicate glass such as silicate glass, alkali silicate glass, soda lime glass, potassium lime glass, lead lime glass, barium glass, borosilicate glass, etc. Although a substrate can be used, the present invention can be cured at a low temperature as described above, so that the effect is exerted particularly in the case of an organic substrate.

In the organic base material, polycarbonate,
Acrylic resins are preferred.

The shape of the base material is not particularly limited.

The method of applying the metal alkoxide-based coating material is not particularly limited, and a commonly used method can be applied, for example, brush, spray coating, dip coating,
Examples thereof include spin coating, roll coating, and flow coating.

[0024]

[Function] By coating a metal alkoxide-based paint on a substrate and placing it in an environment with a relative humidity of 70% or more, the hydrolysis reaction of the residual alkoxy groups in the film and the polycondensation reaction of the residual hydroxyl groups are promoted. Since the fine particle structure forming the coating film is stabilized, a laminated body in which the coating films having high optical property stability are laminated can be obtained.

[0025]

Embodiments of the present invention will be described below. In addition, the evaluation method of each physical property regarding the laminated body shown in the result was as follows.

(1) Refractive index and film thickness The refractive index and film thickness of the coating film of the obtained laminate were measured using an ellipsometer (DVA-36L, manufactured by Mizojiri Optical Co., Ltd.). (2) Aging test 1 The laminated body is kept in an atmosphere of −40 ° C. for 30 minutes, then taken out, and immediately after that, kept in an atmosphere of 80 ° C. for 30 minutes.
This is set as one cycle, then, taken out, and immediately after that, it is placed again in an atmosphere of −40 ° C. to start the second cycle. Such thermal shock test was performed for 210 cycles.
After the thermal shock test was completed, the refractive index and the film thickness were measured. (3) Aging Change Test 2 The laminate was left in an environment of a temperature of 60 ° C. and a relative humidity of 95% for 1 week, then taken out, and the refractive index and the film thickness were measured.

(Example 1) Isopropyl alcohol 15
1 mol of tetraethoxysilane and 6 mol of water containing hydrochloric acid at a ratio of 0.3 wt% were stirred for 2 hours, and the mixed sol was further diluted with isopropyl alcohol to obtain a metal having a solid content concentration of 2.0 wt%. An alkoxide-based paint was obtained. The solid content concentration means that all Si atoms in the coating material are Si.
It is the weight percentage of the SiO _{2 in} the paint when it is considered to be O ₂ .

Polycarbonate plate (made by Teijin Ltd., trade name "Teijin Panlite", 100 mm x
40 mm x 1 mm. In order to improve the film-forming property, the polycarbonate plate was previously subjected to corona discharge treatment under conditions of a distance between the electrode and the substrate of 5 mm, a power supply of 4.5 kW, and a treatment time of 1 second. ) Was dipped, and dip coating was performed at a pulling rate of 300 mm / min. The obtained coated product is heated to a temperature of 80 ° C. and a relative humidity of 95% under an environment of
After standing for a time, a laminate was obtained. Using the obtained laminate,
Each physical property was evaluated by the above evaluation methods, and the results are shown in Table 1.

Example 2 A laminated body was obtained in the same manner as in Example 1 except that the coated product was left in an environment of a temperature of 60 ° C. and a relative humidity of 95% for 500 hours. The physical properties were evaluated and the results are shown in Table 1.

(Example 3) Isopropyl alcohol 30
3 mol and 0.0 mol of tetraethoxysilane with respect to 0 mol
Stir and mix 9 mol of water containing hydrochloric acid at a ratio of 4% by weight for 3 hours.
I combined. This mixture is then added to tetra-iso-propo
A sol in which 7 mol of xyltitanium was added and stirred and mixed for 3 hours
Is further diluted with isopropyl alcohol to obtain a solid concentration
A 2.0% by weight metal alkoxide coating material was obtained. In addition,
The solid content concentration means that all Si atoms in the above coating are SiO 2._Two
And all Ti atoms are TiO_TwoIf you think
Of SiO _TwoAnd TiO_TwoBy weight percentage in Japanese paint
You.

A polycarbonate plate similar to that used in Example 1 was dipped in the obtained coating material, and dip-coated at a pulling rate of 240 mm / min. The obtained coated product was left in an environment of a temperature of 80 ° C. and a relative humidity of 80% for 250 hours to obtain a laminate. Each physical property was evaluated by the above-mentioned evaluation method using the obtained laminate, and the results are shown in Table 1.

(Comparative Example 1) The coated article was not left in a high humidity environment, but in an environment of a temperature of 100 ° C. and a relative humidity of 5% or less.
A laminate was obtained in the same manner as in Example 1 except that it was allowed to stand for a period of time, and its physical properties were evaluated by the above-described evaluation methods. The results are shown in Table 1. .

(Comparative Example 2) The coated product was not left in a high humidity environment, but 250 in a temperature of 80 ° C. and a relative humidity of 50%.
A laminate was obtained in the same manner as in Example 1 except that it was allowed to stand for a period of time, and its physical properties were evaluated by the above-described evaluation methods. The results are shown in Table 1. .

[0034]

[Table 1]

[0035]

In the method for producing a laminate of the present invention, the metal alkoxide-based coating material is applied onto a substrate and placed in an environment with a relative humidity of 70% or more. Since the polycondensation reaction of the residual hydroxyl groups is promoted and the fine particle structure forming the coating is stabilized, a laminate having a coating having high optical property stability is obtained.

Claims (1)

[Claims] 1. A method for producing a laminate, which comprises coating a substrate with a metal alkoxide-based coating and placing it in an environment having a relative humidity of 70% or more.