JPH06218861A - Ultraviolet absorbing laminate and window using the same - Google Patents

Abstract

PURPOSE:To obtain a laminate having sufficient light fastness even against the irradiation with solar rays over a long period of time by adding a specific amt. of an ultraviolet absorber to a lyotropic type cholesteric liquid crystal composed of a linear homopolysaccharide derivative. CONSTITUTION:A lyotropic type cholestric liquid crystal consisting of a linear homopolysaccharide derivative and a solvent is laminated to a substrate 1 to obtain a partially transparent laminate. Herein, a 0.001-5wt.% of an ultraviolet absorbent is added to the liquid crystal 2. As the linear homopolysaccharide derivative, hydroxypropyl cellulose obtained by reacting propylene oxide with cellulose is designated. As the ultraviolet absorber, benzotriazole, hindered amine and benzoate type comds. are designated. By this constitution, a laminate having sufficient light fastness against the irradiation with solar rays over a long period of time is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated body in which a lyotropic cholesteric liquid crystal having excellent thermal stability is laminated and a window using the laminated body.

[0002]

2. Description of the Related Art Conventionally, there have been three types of liquid crystals, nematic, smectic, and cholestic, and they have been extensively researched and developed. It is known that the cholesteric liquid crystal shows a rainbow interference color by selectively reflecting visible light due to the helical molecular arrangement, and this coloration reversibly changes depending on temperature. The liquid crystal also includes a lyotropic liquid crystal that takes a liquid crystal phase by mixing a thermotropic liquid crystal that changes from an individual to a liquid crystal by heating and a solvent.

Here, the present invention relates to a lyotropic cholesteric liquid crystal having a solvent effect, not to a nematic liquid crystal used for a thin display and a thermotropic cholesteric liquid crystal used for a temperature indicating material. Further, as the high molecular type, there are liquid crystals in which a linear homopolysaccharide derivative (for example, "hydroxypropyl cellulose) is dissolved at a high concentration and liquid crystals in which polyamino acid esters (for example, poly-γ-benzyl-L-glutamate) are dissolved in a specific solvent. is there. This lyotropic polymer cholesteric liquid crystal is such that the existence of such liquid crystal is basically known, and the interference colors (purple, indigo, blue, green, yellow, orange, and It is known that the color of red also changes reversibly with temperature, and that the temperature range for coloration depends on the concentration, molecular weight and type of solvent.

Therefore, the inventors of the present invention can also be applied to general organic solvents (for example, acetone, ethanol, propylene glycol, etc.) as a solvent of this lyotropic cholesteric liquid crystal, but especially pay attention to a water solvent as a representative example. Then, by multi-faceted examination of a lyotropic cholesteric liquid crystal composed of a linear homopolysaccharide derivative and water, excellent coloration and reversible change of transparency-opacity due to white turbidity change of phase transition were obtained. This led to the proposal of a weather resistant laminate and a window using the same.

A lyotropic cholesteric liquid crystal composed of a linear homopolysaccharide derivative and water has been studied with regard to the compounds, solvents, additives and the like as its raw materials. However, the durability against light has not been examined. In particular,
When used for a window as in the present invention, it is necessary to satisfy light resistance. The water-soluble linear homopolysaccharide derivative used in the present invention is a colorless compound and does not absorb in the visible region to the near infrared region of 400 nm to 1100 nm, which accounts for about 80% of solar radiant energy. Therefore, it can be said that the liquid crystal used in the present invention is essentially stable to light having a wavelength longer than visible light. However, soda lime sheet glass, which is generally widely used as window glass, absorbs light with a wavelength of 290 nm or less, but it is
It is necessary to absorb ultraviolet rays of 290 nm to 380 nm and obtain sufficient light resistance.

[0006]

A problem to be solved by the invention is that a lyotropic cholesteric liquid crystal comprising a linear homopolysaccharide derivative and a solvent is laminated on a substrate and at least a part of which is transparent. It is an object of the present invention to provide a laminated body having sufficient light resistance even when it is absorbed and irradiated with a solar ray for a long time, and a window using the laminated body.

[0007]

The present invention has been made to solve the above-mentioned problems, and at least a lyotropic cholesteric liquid crystal comprising a linear homopolysaccharide derivative and a solvent is laminated on a substrate. A partially transparent laminate, wherein 0.001 to 5% by weight of an ultraviolet absorber is added to the liquid crystal, and a lyotropic type laminate comprising a linear homopolysaccharide derivative and a solvent. A window using a laminated body in which cholesteric liquid crystal is laminated on a substrate and at least a part of which can be seen through, wherein a laminated body formed by adding 0.001 to 5% by weight of an ultraviolet absorber to the liquid crystal is used. It provides a window.

The present inventors have selected, as a representative example of linear homopolysaccharide derivatives, cellulose having high stability among linear homopolysaccharides, and hydroxypropyl cellulose obtained by reacting the cellulose with propylene oxide is selected. It has been selected, but is not particularly limited thereto. FIG. 2 is a spectroscopic absorption spectrum of the 1% by weight aqueous solution of hydroxypropylcellulose placed in a 1 cm cell made of quartz and measured in the ultraviolet region of 190 nm to 400 nm. Thus, even a linear homopolysaccharide derivative consisting of carbon, oxygen, and hydrogen can
Absorption by tailing from the shoulder is observed in the wavelength range of 0 nm to 380 nm in the ultraviolet region. However, C-C, C
The interatomic bond energy of —O and C—H is 350 nm or less, and it can be said that this object can be satisfied by cutting ultraviolet rays of 350 nm or less in a linear homopolysaccharide derivative in which at least a functional group is a hydroxypropyl group. In addition, the maximum sensitivity wavelength that causes photodegradation of a polymer is generally 2
It is in the wavelength range of 90 nm to 320 nm. In addition, the spectral transmittance at 350 nm of the soda-lime float plate glass mainly used as the substrate in the present invention (a representative example is a product of Central Glass Co., Ltd.) is 3 mm thickness / 78.1%, 5 mm.
Even at a thickness of 19 mm, such as thickness / 70.3%, 10 mm thickness / 54.0%, 19 mm thickness / 33.7%, about one third of the amount of light is still transmitted. However, the spectral transmittance at 300 nm is 3 mm thickness / 0.1%, and the ultraviolet rays below 300 nm are absorbed by the glass substrate. As a result, the tailing weak absorption spectrum of 300 nm in FIG.
To 380 nm to 380 nm ultraviolet light may be absorbed. Furthermore, at least the ultraviolet rays on the short wavelength side of 300 nm to 350 nm, which have a great influence on photodegradation even in this wavelength range, may be cut off.

FIG. 1 is a cross-sectional view of one embodiment of the laminate of the present invention, in which 1 is a substrate, 2 is a lyotropic cholesteric liquid crystal composed of a linear homopolysaccharide derivative having an ultraviolet absorber and a solvent, 3 Is a seal. The ultraviolet absorber mentioned here is a general term for additives that prevent deterioration with respect to ultraviolet rays, as long as it contributes to absorption and stability. The amount of the ultraviolet absorber added may be selected from the range of about 0.001 to 5% by weight, preferably about 0.01 to 0.5% by weight. Examples of ultraviolet absorbers include benzotriazole-based, hindered amine-based, and benzoate-based compounds. More specifically, TINUVIN-P and CHIMASSOR of Ciba-Geigy Japan
B-944FL, TINUVIN-120, etc. and Sumitomo Chemical's Sumsorb 110, 250, 300, 340, 35
There is 0 etc. In particular, when the solvent is water, Sumisorb 110S may be added.

The linear homopolysaccharide derivative as a raw material of the present invention and the solvent are not particularly limited, and additives may be added. As for the water solvent, for example, a liquid crystal added with a water-soluble electrolyte (eg, sodium chloride, potassium chloride, sodium sulfate, etc.) is a phase in which a liquid crystal state that changes color due to the ionic effect of the water-soluble electrolyte changes to a clouded aggregate state. The transition temperature shifted to the low temperature side as compared with the liquid crystal having no water-soluble electrolyte. The degree of this shift temperature is
It was possible to control by the concentration of the water-soluble electrolyte, and by this method the cloudiness onset temperature of the liquid crystal could be freely set and the phase transition temperature could be easily lowered to the room temperature range. The amount of the water-soluble electrolyte added to the aqueous solution is preferably about 0.1 to 10% by weight. Further, a water-soluble compound may be added for the purpose of improving characteristics such as a white turbidity change rate and haze adjustment.

This white turbidity change is caused not only in the laminate which changes its color depending on the temperature of the natural environment, but also at 35 ° C., for example.
When a liquid crystal that undergoes a phase transition in (1) is laminated between flat glass (for example, heat-absorbing glass) and used for a window, especially when direct sunlight such as the summer sun in the summer selectively hits the window glass, the absorption of solar radiation causes The window glass was selectively heated, and as a result, only the irradiated part was selectively clouded to shield light and prevent glare. The feature of this light shielding is that the stronger the irradiation, the higher the temperature of the irradiation surface and the more opaque it becomes. Further, this liquid crystal did not cause convection due to its high viscosity, and automatically changed automatically due to changes in the environment due to the intensity of direct sunlight, movement of the irradiation surface, and the like. This is
It is intended to provide a window having an ideal blind that selectively and automatically shields only the irradiation part. In this way, in order to directly use the energy of direct sunlight,
To protect the liquid crystal, it is essential to absorb ultraviolet rays as in the present invention.

Further, since a laminated body using a plate glass with a transparent conductive film as a substrate can electrically control heat generation of transparent-opaque, when it is used as a window, the electronic curtain can be used without depending on the environment such as sunlight. Windows with windows can be provided. In addition, by selecting the concentration of this linear homopolysaccharide derivative,
A high-concentration aqueous solution that shows a liquid crystal state by supercooling below, and is a colorless transparent substance in a non-liquid crystal state at the daytime use temperature of about 5 ° C to 30 ° C in areas where antiglare is required and changes to cloudiness from about 40 ° C. Are also included in the present invention. More specifically, it is assumed that the present invention also includes a state change of cloudy opaque-colorless and transparent state without color change, and a lyotropic cholesteric liquid crystal comprising the linear homopolysaccharide derivative of the present invention and water is 20 % Means a high-concentration aqueous solution of not less than%.

The shape of the laminated body can be freely selected, and the size is not particularly limited, and it is sufficient that the laminated body has a transparent portion in which the inside can be directly viewed. The substrate is mainly used because glass and plastic are transparent, but metal, ceramics or the like may be used on one side. Further, in the case of a soda-lime glass substrate, when the solvent is a liquid crystal of water, it becomes more stable if a thin film of silicon oxide is coated on the surface to prevent the elution of the alkali content. The encapsulation should be such as to prevent evaporation of the solvent, which is not specifically described here.

The laminated body has a window, an outdoor table,
Widely used outdoors such as advertising lights and tiles. In particular, an excellent window can be obtained by using this laminate for a window. Examples of the windows include windows of ordinary buildings, vehicles such as automobiles and railway cars, and windows of transport planes such as aircraft and elevators. Of course, this window has a broad meaning, and includes a door with a window, a partition, etc., as well as a transparent glass door, a screen, and a wall.

Therefore, the present inventors conducted a light resistance comparison test with and without an ultraviolet absorber. The stack is 1.9m
Liquid crystal was laminated at a thickness of 0.2 mm between substrates of m-thick 60 mm × 60 mm square soda lime glass, and the outer circumference was sealed with a copper tape with an adhesive having a width of 8 mm. The liquid crystal was sufficiently dissolved in 50 parts by weight of hydroxypropyl cellulose (average polymerization degree: 175, viscosity of 2% aqueous solution at 20 ° C .: 8.5 cps, hydroxypropyl group: 62.4%) and 30 parts by weight of water. A high concentration solution was used. As test samples, S1 was a laminate made of liquid crystal having no ultraviolet absorber, S2 was an ultraviolet absorber, and a laminate and a laminate were prepared by adding 0.1 wt% of Sumitomo Chemical's Sumisorb 110S. These samples were irradiated with ultraviolet rays for comparison.
Therefore, the UV irradiator emits a wavelength of 295 nm to 450 nm, and in particular, the UV is an SUV-F2 type manufactured by Eye Graphics Co., which has a level 30 times higher than that of a weather meter. The UV intensity is 100 mw, the black panel temperature is 63 ° C. 8, 24, 48 under irradiation distance of 235 mm
After irradiation for 24 hours, the temperature was returned to room temperature of 24 ° C. and color observation was performed. The results are clear, and S1 having no ultraviolet absorber shows an initial green color of 8 hours after irradiation of orange, showing a color difference of 23.45 and a color change (measured by Minolta color difference meter CR-100). After a lapse of time, it became colorless and pale and cloudy, that is, haze was observed and some air bubbles were generated. After 48 hours, both haze and bubbles expanded. In contrast to S1, S2 was stable without any particular change.

[0016]

INDUSTRIAL APPLICABILITY As described above, according to the present invention, as a result of the lyotropic cholesteric liquid crystal comprising the linear homopolysaccharide derivative and the solvent being stably maintained because the ultraviolet absorber absorbs the ultraviolet rays, It is possible to provide a laminate having sufficient light resistance to irradiation of sunlight for a long period of time and a window using the laminate. As a result, it has become possible to use it with durability even in windows of buildings, vehicles, etc. where the usage conditions are extremely severe.

[Brief description of drawings]

FIG. 1 is an example of a laminate having an ultraviolet absorber according to the present invention.

FIG. 2 is a spectral absorption spectrum from 190 nm to 400 nm of a 1% by weight aqueous solution of hydroxypropyl cellulose.

[Explanation of symbols]

 1 substrate 2 liquid crystal with ultraviolet absorber 3 spacer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location G02F 1/13 500 505 9017-2K

Claims (2)

[Claims] 1. A laminate in which a lyotropic cholesteric liquid crystal comprising a linear homopolysaccharide derivative and a solvent is laminated on a substrate and at least a part of which is transparent, and 0.001 to 5 parts by weight of an ultraviolet absorber is added to the liquid crystal. %, And a laminated body characterized by being added. 2. A window using a laminate in which a lyotropic cholesteric liquid crystal composed of a linear homopolysaccharide derivative and a solvent is laminated on a substrate and at least a part of which is transparent, and an ultraviolet absorber is added to the liquid crystal in an amount of 0.001. From 5% by weight
A window characterized by using a laminated body formed by adding.