RU686191C - Method of manufacturing diffusion chromizing film - Google Patents

Description

The invention relates to methods for producing thermochromic films, in particular thermochromic films based on cholesteric liquid crystals, and can be used for digital or color temperature displays, for visualizing thermal, 9. b infrared radiation, for de (} {there is a copy, in acoustic holography D-medical .it, d, D. Lime method TfJifoToeneHMP thermochromic film, in which a mixture of cholesteric liquid crystals is introduced 8 solution of a polymer resin in an organic solvent (for example , acrylic resin in toluene.) After “evaporation of the solvent, the polymer base remains with the liquid crystal distributed in it. However, such films are unstable - their color and temperature characteristics change rapidly over time, and the brightness of the colors changes The closest known among the technical nature and the achieved effect to the proposed one is the method of manufacturing a thermochromic film based on cholesteric liquid crystals, which consists in 3 that the thermochromic composition based on cholesteric liquid crystalloses is emulsified in a solution of a hydrophilic polymer, for example polyvinyl alcohol, the resulting emulsion is applied to a substrate and dried. The film formed has the property of selective light scattering depending on temperature, which allows its use for temperature indication. In order to achieve high color contrast, a light-absorbing black layer is further provided, which is most suitably applied as a carbon black emulsion in an aqueous solution of polyvinyl alcohol. After applying a blackened light-absorbing layer, the film is re-dried. To achieve high stability over time, a further protective layer is applied in the form of an aqueous solution of polyvinyl alcohol, after which drying is carried out. Thus, the method under consideration consists in sequentially applying three layers to the substrate: protective, working and blackening, and after applying each layer, it is dried for 3-4 hours. As a result, the production of a thermochromic film is a lengthy process (12-24 h, depending on the drying mode), which is a significant disadvantage of the isaesta method. In addition, due to the oxidation of components during drying, as well as ruptures and fusion of pseudocapsules, the color-selective scattering brightness decreases. There is also a hi-dimensional distribution of colors on the surface of the film. The aim of the invention is to increase the brightness of the colors of the film and reduce the duration of its manufacture. The goal is achieved in that in the known method of manufacturing a thermochromic plaque. including the sequential deposition of layers from an aqueous solution of a hydrophilic polymer, from an aqueous emulsion of cholesteric liquid crystals containing the indicated polymer, and from a suspension of soot in an aqueous solution of the same polymer and their drying, each deposited layer is cooled to a gel state, and the wire is dried by drying t after cooling the last layer. A method of manufacturing a film is as follows. . Example 1. A 15% aqueous solution of polyvinyl alcohol is prepared and, using a contact die, applied to an organic glass substrate, then cooled to a gel-like state, which corresponds to 1 ° C, resulting in polyvinyl alcohol desalination and fixing it in the form of a gel-like layer. In a similar manner to the thus formed protective layer, 10 g of the cholesteric composition (55% by weight of cholesteryl oleates and 45% by weight of cholesteryl pelargonate in 75 ml of a 15% aqueous solution of polyvinyl alcohol) are applied. The film is cooled a second time until the applied emulsion transitions to a gel state (up to). A 5% suspension of carbon black in a 15% aqueous solution of polyvinyl alcohol is applied in the same manner to the formed working layer, after which the film is again cooled until the applied suspension passes and the gelled state (up to). The film is then dried at 30 ° C for 3 hours at a constant relative humidity of 20%. Example 2. A film was prepared analogously to Example 1, but instead of cooling to a gel state, after applying each layer, drying was carried out at 30 ° C for 3 hours at a constant relative humidity of 20%. Sample A t20% aqueous solution of polyvinyl alcohol is prepared and applied with a contact die to the under / south of a polished stainless steel sti, and then cooled to gel oor: kneszgo has combined to 2 ° C. An emulsion is applied to the protective layer thus formed 25 g of a cholesteric composition (50 wt.% Cholesterol, 30 wt.% Cholesteryl pelargonate. May 20.% Cholesteryl chloride in 100 ml. 20% aqueous solution of polyvinyl alcohol), after which the film is cooled until the applied emulsion in a gel state . A 5% suspension of soot in a 20% aqueous solution of polyethyl alcohol is applied to the formed working layer, after which the film is again cooled until the applied emulsion passes (gel state 8 (foo 2 ° C). Then, the film is dried at 25 ° С for 4 hours at a constant relative humidity of 20%. Example 4. A film was obtained analogously to Example 3, but instead of cooling to a gel state, after each layer was applied, drying was carried out at 25 ° C for 4 hours at a constant relative humidity of 20%. Examples 5-12. A film is prepared analogously to Examples 1-4 using various cholesteric compositions. Tables 1 and 2 show the compositions, manufacturing conditions, and quality of the resulting film. As can be seen from the above data, the application of the proposed method allows to reduce the duration of the film production by 3 times with a simultaneous decrease in the intensity of the selective scattering a 2-2.5 times. Thus, the proposed method makes it possible to increase both the productivity of the equipment used and the quality of the obtained thermochromic films. 6) ESA Patent 3620889, CL 161-5, published. 1971 British Patent 1161039; cells, G 1 D, olublik. 1969.

Cholesteric composition

example

91% cholesteryl oleate

 5 . 9% cholesteryl pergonate

6 7

m

79% cholesteryl oleate 21% cholesteryl pergonate

8

| «|

92% cholesteryl oleate, 3%

9. cholesterolzalerate, 5% cholesterylpelargonate

10 11

80% cholesteryl oleate, 10% cholesteryl undecylite, 10% cholesteryl alerate

12

Table,

Methodology

composition manufacturing

but according to example

acc. to example 2 acc. with example 2

acc. with an example of e resp. with example 3

in accordance with example 4 acc. with example 3

acc. with example 4

L is the wavelength of light.

Claims (1)

: The claims METHOD FOR PRODUCING THERMO; CHROMIUM FILM, including after jqoBaTenbHoe the deposition of layers from an aqueous solution of a hydrophilic polymer, from an aqueous emulsion of cholesteric liquid crystals containing the specified polymer, from a suspension of soot in table 2 an aqueous solution of the same polymer and drying thereof, characterized in that what. in order to increase the brightness of the color of the film and reduce the time for its manufacture, each deposited layer is cooled to a gel state, and drying is carried out after cooling of the last layer.