JPH0680446A - Dimmable laminated glass - Google Patents

Abstract

(57) [Summary] [Object] To provide a dimmable laminated glass which is inexpensive, has a high dimming function, has little deterioration with time, and can artificially adjust the light transmittance as necessary. [Structure] A polyvinyl butyral aqueous solution (average polymerization degree: 800, acetalization degree: 9 mol% by weight, aqueous solution concentration: 10% by weight) having a cloud point of 39 to 40 ° C. between two upper and lower transparent inorganic glass plates 10. The light layer 40 is encapsulated to produce a dimmable laminated glass. This dimmable laminated glass is transparent at an ambient temperature of, for example, 25 ° C.
When the temperature rises to 5 ° C, it becomes opaque (milky white) automatically. In addition, the total light transmittance was 86.3% in the initial transparent state (immediately after production) and 47.9% in the opaque state, and the transmittance with time (3
8,000 hours) when transparent, 85.0%, when opaque 48.
It is 9%, which shows good dimmability with little deterioration with time. The light transmittance can be artificially adjusted by providing a heating unit and / or a cooling unit for the light control layer 40.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used, for example, in window materials for buildings and automobiles, is inexpensive, has little deterioration over time, and is capable of artificially adjusting the transmittance of visible light as necessary. Regarding glass.

[0002]

2. Description of the Related Art An aqueous solution of an N-isopropylacrylic (or methacrylic) amide polymer has a so-called cloud point, which is transparent at a temperature below a certain temperature (for example, 30 ° C. or less) and becomes opaque at a temperature higher than that temperature.

An aqueous solution of this polymer is used as a light control layer, and the light control layer is sandwiched between two transparent plates to prepare a light blocking material, which is used, for example, in greenhouses, show windows and buildings. It has been proposed to use it on a wall or a skylight to automatically reduce an increase in internal temperature under hot weather in summer (see, for example, Japanese Patent Publication No. 61-7948).

Further, there has been proposed a light control glass in which a nematic liquid crystal light control material is sandwiched between two transparent plates with transparent electrodes. This is to control the light transmittance by applying an electric field to the liquid crystal substance (see, for example, JP-A-1-
62615).

In addition, a method of using an electrochromic material which controls the light transmittance by utilizing a redox reaction,
A method of using a photochromic material utilizing light energy such as ultraviolet rays has also been proposed (for example, Japanese Patent Application Laid-Open No. HEI 2-
(See Japanese Patent No. 85274).

[0006]

However, the method of using an aqueous solution of N-isopropylacryl (or methacryl) amide polymer has a large deterioration of its dimming function with the passage of time, and the light is diminished regardless of the ambient temperature. It is impossible to artificially control the transmittance of the.

The method of using a nematic liquid crystal substance is limited in its use because an expensive liquid crystal is generally used. Further, since the light resistance of liquid crystal is insufficient, it is disadvantageous for use as a window material exposed outdoors. Moreover, although the line-of-sight property is good when opaque without applying an electric field, the light-shielding property is poor.

Further, the method of using an electrochromic material or a photochromic material cannot be used as a window material that requires a dimming function for a long period of time because its dimming function deteriorates greatly over time.

The present invention is intended to solve the above problems, and an object thereof is to have a high dimming function at a low cost, with little deterioration over time, and further to artificially adjust the light transmittance as required. The purpose of the present invention is to provide a dimmable laminated glass that can be adjusted dynamically.

[0010]

In order to achieve the above object, the dimmable laminated glass of the present invention has a dimming layer made of an aqueous polyvinyl acetal solution having a cloud point sandwiched between two transparent plates. ing. Furthermore, it preferably has a heating means and / or a cooling means for the light control layer.

The aqueous polyvinyl acetal solution used in the present invention must have a so-called cloud point, which is transparent at a temperature below a certain temperature and becomes opaque at a temperature above that temperature.

The cloud point of the aqueous solution is preferably in the range of 0 to 80 ° C., more preferably in the range of 15 to 55 ° C., in consideration of the environmental temperature in which the product is used. The concentration of the aqueous solution is generally 0.1 to 20% by weight.
It is considered as a degree.

The aqueous polyvinyl acetal solution having such a cloud point can be produced by a known polyvinyl acetal production technique.

That is, a specific polyvinyl acetal obtained by subjecting polyvinyl alcohol to a condensation reaction (acetalization reaction) with aldehydes can be prepared by completely dissolving it in an appropriate amount of cold water or room temperature water.

As the aldehydes, generally used are monoaldehydes such as formaldehyde, acetaldehyde, butyraldehyde and hexyl aldehyde, and single aldehydes such as dialdehydes such as glyoxal, or mixed aldehydes of two or more kinds.

The polyvinyl acetal aqueous solution having a cloud point generally has an acetalization degree of 2 to 70 mol%.
And is prepared using polyvinyl acetal having an average degree of polymerization of 300 to 3000.

The above-mentioned numerical values are merely guidelines for use, and there is a cloud point even if the numerical values are out of the range. On the contrary, there are some which have no cloud point even within the range of this numerical value.

For example, the degree of acetalization depends on the type of polyvinyl acetal used. When polyvinyl butyral is used, it has a cloud point with an acetalization degree of about 5 to 25 mol%. When polyvinyl acetoacetal is used, it has a cloud point when the degree of acetalization is about 30 mol% or more.

The cloud point also differs depending on the saponification degree of polyvinyl alcohol used in the production of polyvinyl acetal, and polyvinyl alcohol having a saponification degree of 60 mol% or more is generally used.

In order to adjust the cloud point, a coagulant composed of a water-soluble salt can be dissolved in the polyvinyl acetal aqueous solution.

Examples of such coagulants include MSO ₄ , M
SO ₃ , MNO ₃ , MNO ₂ , MPO ₄ , MHPO ₄ ,
Examples thereof include MCO ₃ , MHCO ₃ and MCl (provided that M is an alkali metal or an alkaline earth metal). These water-soluble salts are dissolved in the polyvinyl acetal aqueous solution in the minimum necessary amount within the range not exceeding the saturated solubility.

Further, in order to assist dispersion and emulsification in a system in which an aqueous polyvinyl acetal solution is phase-separated, and to adjust the viscosity, water-soluble polymer substances such as polyvinyl alcohol, polyvinylpyrrolidone, carboxymethyl cellulose, dextrin, and gum arabic. Can be dissolved in a small amount.

To sandwich a polyvinyl acetal aqueous solution having a cloud point as a light control layer between two transparent plates, for example, two transparent plates made of transparent organic glass such as transparent inorganic glass or polycarbonate are opposed to each other. Then, a space is formed between them through a spacer. Next, the above-mentioned aqueous solution is sealed in this space, and the periphery thereof is sealed with an appropriate sealing material.

The dimmable laminated glass thus obtained is
It becomes transparent below the cloud point and becomes opaque above the cloud point, and has a light control function automatically. However, the light transmittance cannot be artificially controlled. In order to artificially control the light transmittance, heating means and / or cooling means for the light control layer are provided.

The heating means can be constructed, for example, by forming a transparent conductive thin film on a transparent plate and connecting a power source terminal to this conductive thin film to energize the conductive thin film. In this case, the conductive thin film serves as a heating element.

Specifically, an ITO (mixture of indium oxide and tin oxide) thin film is formed on at least one transparent plate, and the light control layer is sandwiched between two transparent plates. Then, by connecting a power source terminal to the ITO thin film, a dimmable laminated glass provided with a heating means can be obtained.

In order to enhance the heat transfer effect to the light control layer, it is preferable to form the ITO thin film, which is a heating element, on the surface of the light control layer. The resistance of the conductive thin film (ITO thin film) used is preferably 10 to 400 Ω / sq.

When the resistance of the conductive thin film is less than 10 Ω / sq, the transparency of the ITO thin film is lowered and the resistance is 400%.
Those exceeding Ω / sq are not preferable because it takes too long to reach the required temperature.

As another embodiment of the heating means, a high resistance wire such as a nichrome wire may be preliminarily spread on the transparent plate in a mesh shape or in parallel to form a heating element.

Further, the cooling means, for example, one transparent plate encapsulating the light control layer and a separately prepared transparent plate are opposed to each other with a spacer interposed therebetween, and the periphery thereof is surrounded by the refrigerant inlet and the refrigerant. Seal with an appropriate seal, leaving the outlet and
A refrigerant space is formed.

Then, if the refrigerant is passed through the refrigerant inlet which communicates with the refrigerant space, a dimmable laminated glass having a cooling means can be obtained. As the refrigerant, it is preferable to use a fluid such as cooled water or air.

When the cloud point of the light control layer is room temperature or higher, the laminated glass is usually transparent. To make the laminated glass opaque, it is heated by a heating means to make it opaque. On the contrary, when the cloud point of the light control layer is at room temperature or lower, the laminated glass is usually opaque. To make the laminated glass transparent, it is cooled by a cooling means to be transparent.

In general, the heating method is simpler and cheaper than the cooling method, so that the heating method is preferable. Further, if both the heating means and the cooling means are provided, the cloud point changes quickly, and a transparent state and an opaque state can be obtained in a short time.

It is preferable that the light control layer is provided with a moisture-proof layer having an insulating function. The moisture-proof layer is formed between the light control layer and the heating means (conductive thin film or high resistance wire). Specifically, it is formed on the transparent plate on which the conductive thin film or the spread high resistance wire is formed.

The moisture-proof layer having an insulating function prevents direct contact between the light control layer and the heating means (conductive thin film or high resistance wire), prevents the risk of electric leakage, etc. It has the function of further improving deterioration over time.

As the moisture-proof layer having an insulating function, both inorganic and organic substances can be used. For example, a SiO ₂ film can be formed on the transparent plate on which the transparent conductive film and the high resistance wire are formed by a sputtering method, a vapor deposition method or the like. The film thickness of this SiO ₂ is 30 in order to obtain a sufficient moisture-proof effect and insulating property, and in consideration of heat transfer property.
It is desirable to be in the range of 0 to 4000Å.

As the transparent plate, safety glass using an intermediate film can be used. Here, examples of the intermediate film include a polyvinyl butyral intermediate film, a vinyl chloride-based intermediate film, a urethane-based intermediate film, and an EVA-based intermediate film.

[0038]

The polyvinyl acetal having a cloud point used in the present invention can be easily synthesized from an inexpensive compound by a conventional technique and can be manufactured at a low cost.

The polyvinyl acetal aqueous solution having a cloud point has a different visible light transmittance between a state below the cloud point and a state above the cloud point, and is transparent when the sunlight is weak and the environmental temperature is below the cloud point. Next, it transmits light rays well.

On the contrary, when the sunlight becomes strong and the ambient temperature rises above the cloud point, it becomes opaque and it becomes difficult for light rays to pass therethrough, and the rise in internal temperature can be automatically suppressed to a low level.

Further, when the light control layer is heated above the cloud point by the heating means, the laminated glass becomes in an opaque state. If it is desired to maintain the opaque state, the heating may be maintained. Just stop.

When the dimming layer is cooled to below the cloud point by the cooling means, the laminated glass becomes transparent and changes to a state in which visible light can be transmitted.

[0043]

EXAMPLES Examples and comparative examples of the present invention will be shown below. Example 1 See FIG. Two upper and lower transparent inorganic glass plates (thickness 1mm)
10 are opposed to each other via a spacer 20 made of an acrylic resin with a space therebetween, and the periphery thereof is sealed with a sealing body 30 made of an epoxy resin leaving an inlet for an aqueous solution to form a space (thickness 1 mm). did.

After pouring 40 an aqueous solution of polyvinyl butyral (average degree of polymerization: 800, degree of acetalization: 9 mol%, concentration of aqueous solution: 10% by weight) having a cloud point of 39 to 40 ° C. into this space, the injection port of the aqueous solution was sealed. Then, a dimmable laminated glass was produced.

This dimmable laminated glass was transparent at an ambient temperature of 25 ° C. Further, this dimmable laminated glass became opaque (milky white) when it was heated to 45 ° C.

Further, in order to evaluate the dimming property and deterioration with time, the dimming laminated glass produced was measured according to JIS R
According to 3212, the total light transmittance was measured at the initial stage (immediately after the production) and the elapsed time (after 3000 hours).

As a result, in the initial stage, the transparent state was 86.3.
%, 47.9% when opaque, 85.0% when transparent and 48.9% when opaque over time, showing good dimming resistance without deterioration.

Example 2 See FIG. In Example 1, an ITO thin film (thickness 1000 Å) 50 having a resistance of 50 Å / sq was deposited on the upper surface of the lower transparent inorganic glass plate 10, and a SiO ₂ thin film (thickness 1000 Å) 60 was deposited thereon. . Reference numeral 51 is a power supply terminal. Otherwise, perform the same as in Example 1,
A dimmable laminated glass was produced.

The dimmable laminated glass obtained was transparent at an ambient temperature of 25 ° C. Further, this dimmable laminated glass became opaque (milky white) when it was heated to 45 ° C.

The initial light transmittance (immediately after production) of this dimmable laminated glass was 86.5% when it was transparent and 48.1% when it was opaque. showed that.

Further, this dimmable laminated glass was placed at 25 ° C.
When the ITO thin film 50 was energized by using a 100-volt power source at the ambient temperature of No. 2, it became opaque in about 10 seconds after energization, and became transparent in about 10 seconds when the energization was stopped.

Example 3 See FIG. In Example 2, a net-like nichrome wire 70 was used instead of the ITO thin film 50. Reference numeral 71 is a power supply terminal. Other than that was performed like Example 3, and the light control laminated glass was produced.

The obtained dimmable laminated glass was transparent at an ambient temperature of 25 ° C. Further, this dimmable laminated glass became opaque (milky white) when it was heated to 45 ° C.

The initial light transmittance (immediately after production) of this dimmable laminated glass was 84.5% when it was transparent and 47.7% when it was opaque. showed that.

Further, this dimmable laminated glass was placed at 25 ° C.
When the reticulated nichrome wire 70 was energized by using a 100-volt power source at the ambient temperature of No. 3, it became opaque about 10 seconds after the energization, and became transparent about 10 seconds after the energization was stopped.

Example 4 See FIG. In Example 2, the lower transparent inorganic glass plate 10 and another transparent inorganic glass plate 11 (thickness 1 mm) 11
Spacers 21 were made to face each other with a space therebetween, and the periphery thereof was sealed with a seal body 31 leaving a refrigerant inlet 81 and a refrigerant outlet 82 to form a refrigerant space (thickness 1 mm) 80. Other than that was performed like Example 2, and the light control laminated glass was produced.

The dimmable laminated glass obtained was transparent at an ambient temperature of 25 ° C. Further, this dimmable laminated glass became opaque (milky white) when it was heated to 45 ° C.

The total light transmittance of the dimmable laminated glass at the initial stage (immediately after its production) was 85.7% when it was transparent and 48.0% when it was opaque. showed that.

Further, this dimmable laminated glass was heated to 50 ° C.
To the opaque state by heating to the refrigerant inlet 81 to outlet 8
When the air of 25 ℃ was circulated to 2, the heart was about 1 after circulation.
It became transparent in 0 seconds.

Example 5 In Example 2, instead of the polyvinyl butyral aqueous solution 40 having a cloud point of 39 to 40 ° C., the cloud point is 42 to 44 ° C.
Polyvinyl acetoacetal aqueous solution (aqueous solution concentration 15
Wt%) was used. Other than that was performed like Example 2, and the light control laminated glass was produced.

The obtained dimmable laminated glass was transparent at an ambient temperature of 25 ° C. Further, this dimmable laminated glass became opaque (milky white) when it was heated to 45 ° C.

The total light transmittance of this dimmable laminated glass at the initial stage (immediately after production) was 86.7% when it was transparent and 50.2% when it was opaque. showed that.

Further, this dimmable laminated glass was placed at 25 ° C.
When the ITO thin film 50 is energized at the ambient temperature of
It becomes opaque about 20 seconds after turning on the power, and about 10 when turning off the power.
It became transparent in seconds.

Example 6 In Example 1, about 2% by weight of sodium sulfate was dissolved in an aqueous polyvinyl butyral solution 40 having a cloud point of 39 to 40 ° C. to adjust the cloud point of the aqueous solution 40 to 32 to 33 ° C. . Other than that was performed like Example 1, and the light control laminated glass was produced.

This dimmable laminated glass was transparent at an ambient temperature of 25 ° C. Further, this dimmable laminated glass became opaque (milky white) when it was heated to 45 ° C.

The total light transmittance of this dimmable laminated glass at the initial stage (immediately after production) was 86.3% when it was transparent and 49.0% when it was opaque. showed that.

Comparative Example 1 In Example 1, a nematic liquid crystal (RO) was used instead of the polyvinyl butyral aqueous solution 40 having a cloud point of 39 to 40 ° C.
-TN-403: manufactured by Rodick Co., Ltd. was dispersed in a polymer matrix (BY-301B: manufactured by Asahi Denka Co., Ltd.), and a liquid crystal light control layer composed of an emulsion of several μm of liquid crystal microcapsule was used.

Further, an ITO thin film (thickness 1000 Å) was vapor-deposited on the surfaces of the upper and lower transparent inorganic glass plates 10 in contact with the liquid crystal light control layer, and power terminals were connected to the upper and lower ITO thin films. Other than that was performed like Example 1, and the light control laminated glass was produced.

The initial (immediately after production) total light transmittance of this dimmable laminated glass was 88.6% when transparent and 83.0% when opaque, and the total light transmittance when opaque was high.
Poor dimming.

The transparent state means that a voltage of 100 V is applied to the power source terminals of the upper and lower ITO thin films.
The opaque state is a milky white state when no voltage is applied to the power source terminals of the upper and lower ITO thin films.

Comparative Example 2 In Example 1, the polyvinyl butyral aqueous solution having a cloud point of 39 to 40 ° C. was replaced with a poly-N-isopropylacrylamide aqueous solution having a cloud point of 28 to 32 ° C. (aqueous solution concentration 4% by weight). A light control layer was used. Other than that was performed like Example 1, and the light control laminated glass was produced.

This dimmable laminated glass was transparent at an ambient temperature of 25 ° C. Further, this dimmable laminated glass became opaque (milky white) when it was heated to 45 ° C.

The total light transmittance of this dimmable laminated glass was 86.3% when it was transparent at the initial stage (immediately after the production).
44.9% when opaque, with time (after 3000 hours)
Then, it was 83.5% when it was transparent and 57.0% when it was opaque, and it is easy to deteriorate and the dimming property is not good.

Comparative Example 3 In Example 1, instead of the polyvinyl butyral aqueous solution 40 having a cloud point of 39 to 40 ° C., a polyvinyl butyral aqueous solution having no cloud point (average polymerization degree 800, acetalization degree 3 mol%, aqueous solution concentration) was used. 10% by weight) was used. Other than that was performed like Example 1 and the laminated glass was produced.

This laminated glass was transparent at an ambient temperature of 25 ° C., and even if it was heated to raise the temperature, it did not become opaque (milky white) but remained transparent and had no light control function. The initial total light transmittance was 86.5%.

[0076]

As described above, in the light-controllable laminated glass of the present invention, the light-controlling layer made of an aqueous polyvinyl acetal solution having a cloud point is sandwiched between two transparent plates. It becomes transparent when it is below the cloud point, becomes opaque when the environmental temperature is above the cloud point, and the light transmittance becomes low, and it has a high dimming function automatically, and it is cheap and has little deterioration of the dimming function. A dimmable laminated glass is obtained.

Further, the dimmable laminated glass of the present invention which has a heating means and / or a cooling means for the light control layer has an advantage that the light transmittance can be artificially controlled in addition to the above effects. is there.

Therefore, when the former dimming laminated glass is used for a skylight of a building or an automobile, a greenhouse or a window of a show window, for example, it becomes an opaque state automatically in the hot sun in summer and blocks light rays. The rise in internal temperature can be reduced.

When the latter dimmable laminated glass is used, for example, in windows of buildings or automobiles, it can be artificially made into an opaque state to block light rays and impart a blind or blind function. It is convenient.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a laminated glass of Example 1 according to the present invention.

FIG. 2 is a sectional view of a laminated glass of Example 2 according to the present invention.

FIG. 3 is a sectional view of a laminated glass of Example 3 according to the present invention.

FIG. 4 is a sectional view of a laminated glass of Example 4 according to the present invention.

[Explanation of Codes] 10 Transparent Inorganic Glass Plate 11 Transparent Inorganic Glass Plate 20 Spacer 21 Spacer 30 Sealing Material 31 Sealing Material 40 Dimming Layer 50 Heating Means (ITO Thin Film) 51 Power Supply Terminal 60 Insulation / Moisture Proofing Layer (SiO ₂ Thin Film) 70 Heating means (reticulated nichrome wire) 71 Power supply terminal 80 Refrigerant space 81 Refrigerant inlet 82 Refrigerant outlet

Claims (2)

[Claims] 1. A dimmable laminated glass, wherein a dimming layer made of a polyvinyl acetal aqueous solution having a cloud point is sandwiched between two transparent plates. 2. The dimmable laminated glass according to claim 1, further comprising heating means and / or cooling means for the light control layer.