CN105316003A - Flexibility solar heat preservation liquid-crystal-polymer thin film and preparing method thereof - Google Patents

Abstract

The invention relates to a flexible solar thermal insulation liquid crystal polymer film and a manufacturing method thereof. It includes the following components: liquid crystals account for 58.5% to 78.5%, azo dyes account for 1% to 3%, and polymers account for 19.5% to 39.5%. The preparation method of the flexible solar thermal insulation liquid crystal polymer film of the present invention comprises the following steps: 1) fully mixing liquid crystal, azo dye, and polymer prepolymer in a dark room or under red light; 2) coating to a thickness of 10 -500um liquid film; 3) Irradiate with ultraviolet light for 0.5-30 minutes to initiate a polymerization reaction, so that liquid crystal and azo dyes form droplets and distribute in the polymer to prepare a flexible solar thermal insulation liquid crystal polymer film. The flexible solar thermal insulation liquid crystal polymer film prepared by the present invention can heat the objects and air covered by the film under the irradiation of high-energy light in sunlight; when there is no sunlight at night, it can reflect the infrared rays emitted by the objects covered by the film , so as to reduce energy loss and achieve better heat preservation effect.

Description

A flexible solar thermal insulation liquid crystal polymer film and its manufacturing method

technical field

The invention relates to a flexible solar thermal insulation liquid crystal polymer film and a manufacturing method thereof, belonging to the solar energy utilization technology.

Background technique

Today is an era of rapid technological development, and the consumption of energy is increasing, so the requirements for energy conservation and environmental protection are getting higher and higher. Solar energy has attracted widespread attention as a renewable clean energy.

At present, one way of using solar energy is the greenhouse plastic greenhouse in the agricultural field, which uses sunlight to heat up the greenhouse during the day and maintains the temperature of the plastic greenhouse by reducing convection. However, ordinary plastic films cannot block the infrared radiation of objects in the greenhouse at night, resulting in large heat loss.

Another way to use solar energy is solar water heaters, which convert light energy into heat energy, store it in liquid substances such as water with a large specific heat, and then use it, although the use of thermal insulation materials and vacuum reduces the convection and heat dissipation of heat. Conduction loss, but at night, the heat still has a large heat loss through the infrared radiation of the heat collecting tube.

Due to the infrared radiation of objects, this type of solar energy utilization method has a large heat loss problem at night.

PDLC is currently a common film material that changes optical reflectivity. By applying an electric field on both sides of the PDLC film, the order of the liquid crystal molecules in the liquid crystal droplets in the film is changed to control the optical reflectivity of the PDLC film. However, this method has many problems such as complex manufacturing process and high cost, changing the light reflectivity of the film requires a control device, high application cost, and energy consumption in the control process.

Under the action of external light, azo compounds will undergo molecular isomerization, that is, under the irradiation of high-energy light such as ultraviolet light, azo molecules will be isomerized to a high-energy structural state, and the molecular form will take a certain shape; After disappearing, through infrared light or thermal relaxation, the azo molecule will return to a low-energy structural state, and the molecular form will return to its original form.

Contents of the invention

The object of the present invention is to provide a flexible solar thermal insulation liquid crystal polymer film that can reflect infrared rays at night in consideration of the above problems.

Another object of the present invention is to provide a simple, convenient and practical method for manufacturing a flexible solar thermal insulation liquid crystal polymer film.

The technical solution of the present invention is: the flexible solar thermal insulation film of the present invention includes the following components: liquid crystals account for 58.5% to 78.5%, azo dyes account for 1% to 3%, and polymers account for 19.5% to 39.5%. .

The manufacturing method of the flexible solar thermal insulation film of the present invention comprises the following steps:

1) Fully mix the liquid crystal, azo dye, and polymer prepolymer in a dark room or under red light;

2) Coating into a liquid film with a thickness of 10-500um;

3) Irradiate with ultraviolet light for 0.5-30 minutes to initiate a polymerization reaction, so that liquid crystals and azo dyes form microdroplets and distribute in the polymer to prepare a flexible solar thermal insulation liquid crystal polymer film.

The invention aims at the problem of heat loss caused by infrared radiation, and the flexible solar heat preservation liquid crystal polymer film prepared by using azo liquid crystal polymer can transmit sunlight during the day and realize the heating of the object covered by the film; at night, it can reduce the infrared radiation of the covered object. Reflection, so that the infrared radiation will not be lost to the outside, so as to achieve a better heat preservation effect. The flexible solar thermal insulation liquid crystal polymer film of the present invention uses the high-energy light in the sunlight to convert the transmission and reflection of the film, does not consume energy itself, and does not require additional control equipment, which is convenient for large-scale use and promotion, and is especially suitable for agricultural production. Applications such as plastic insulation greenhouses and solar water heaters.

In the existing liquid crystal polymer film, the liquid crystal is distributed in the polymer in the form of tiny droplets, and the application of transparent and opaque film is realized under the condition of different electric field conditions by using the optical anisotropy of the liquid crystal material. For ordinary liquid crystal polymer films, the orientation of liquid crystals is controlled by applying an external electric field through transparent electrodes, that is, the transparency of the film is controlled by the voltage applied to the electrodes.

Azo compounds are substances with the same molecular formula that can change the internal structure of the molecule under the irradiation of high-energy light. When the high-energy light does not exist, the internal molecules will relax back to the original state.

The flexible solar thermal insulation film prepared by using azo, liquid crystal and polymer, realizes the photoisomerization of azo molecules under the irradiation of high-energy light components of sunlight, and induces the order of liquid crystal molecules in liquid crystal droplets in the polymer film The azo liquid crystal polymer film is transparent to the incident sunlight, thus warming the objects and air covered by the film; when there is no sunlight at night, the azo molecules return to their original state, and the liquid crystal molecules in the liquid crystal droplets Losing order, the azo liquid crystal polymer film is opaque, reflecting the infrared rays emitted by the objects covered by the film, thereby reducing energy loss and achieving better heat preservation effect.

The flexible solar thermal insulation (liquid crystal) film proposed by the present invention is to irradiate the azo material with the ultraviolet component in the sunlight, and induce the molecular isomerization of the azo material to realize the orientation control of the liquid crystal, so no additional control facilities are needed, and the transparency and opacity can be automatically completed The conversion greatly facilitates the application implementation.

Description of drawings

Figure 1 is a schematic diagram of the structure of an ordinary liquid crystal polymer film, 1 is an isotropic transparent polymer, 2 is a liquid crystal droplet in which the liquid crystal molecules are arranged in disorder, and 3 is a liquid crystal droplet in which the liquid crystal molecules are arranged in an orderly manner under the action of an electric field. drop, 4 is the liquid crystal molecule in the liquid crystal droplet, and 5 is the transparent conductive electrode.

Fig. 2 is a schematic diagram of the structure of the azo liquid crystal polymer film of the present invention, 1 is an isotropic transparent polymer, 6 is a liquid crystal droplet in which liquid crystal molecules are disorderly arranged under the coupling of low-energy state azo molecules, and 7 is a high-energy state Liquid crystal droplets in which liquid crystal molecules are arranged in an orderly manner induced by azo molecules, 8 is liquid crystal molecules in azo liquid crystal droplets, 9 is azo molecules in a low energy state, and 10 is azo molecules in a high energy state.

Figure 3 shows a schematic diagram of the photoisomerization of azo compounds in the present invention, 11 is the low-energy state of azo molecules, and 12 is the high-energy state of azo molecules, when the azo molecules receive the irradiation of high-energy light, Absorbing the energy of light, the molecular form changes, isomorphism into a high-energy state; when the high-energy light is no longer irradiated, the azo molecules in the high-energy state return to a low-energy state under the irradiation of infrared low-energy light or through thermal relaxation.

detailed description

Example 1:

The following components: liquid crystal E7 accounted for 68.5%, methyl red azo dye accounted for 2%, polymer prepolymer (with photoinitiator) accounted for 29.5%, fully stirred evenly in a red light or dark place; Coated into a liquid film with a thickness of 50um; irradiated with an ultraviolet lamp for 10 minutes to complete the polymerization reaction of the polymer and make a flexible solar thermal insulation liquid crystal polymer film.

Example 2:

The following components: liquid crystal E7 accounted for 74.5%, methyl yellow azo dye accounted for 1%, polymer prepolymer (with photoinitiator) accounted for 24.5%, fully stirred evenly in a red light or dark place; Coated into a liquid film with a thickness of 30um; irradiated with an ultraviolet lamp for 20 minutes to complete the polymerization reaction of the polymer and make a flexible solar thermal insulation liquid crystal polymer film.

Example 3:

Mix the following components: liquid crystal E9 accounts for 64%, methyl red azo dye accounts for 1%, polymer prepolymer (with photoinitiator) accounts for 35%, and stir well in a red light or dark place; Coated into a liquid film with a thickness of 30um; irradiated with an ultraviolet lamp for 3 minutes to complete the polymerization reaction of the polymer and make a flexible solar thermal insulation liquid crystal polymer film.

The flexible solar thermal insulation film formed in the above embodiments replaces the common plastic film, which transmits sunlight in the daytime and is opaque at night, so that the infrared radiation of the covered objects will not be lost, so that the solar energy can be used more effectively.

The above-mentioned embodiments are used to illustrate the present invention, rather than to limit the present invention. Within the spirit of the present invention and the protection scope of the claims, any modification and change made to the present invention will fall into the protection scope of the present invention.

Claims (2)

1. A flexible solar thermal insulation liquid crystal polymer film, characterized in that it includes the following components: liquid crystal accounts for 58.5% to 78.5%, azo dye accounts for 1% to 3%, and polymer accounts for 19.5% to 39.5%. . 2. The manufacture method of the flexible solar thermal insulation liquid crystal polymer film according to claim 1, is characterized in that comprising the steps: 1) Fully mix the liquid crystal, azo dye, and polymer prepolymer in a dark room or under red light; 2) Coating into a liquid film with a thickness of 10-500um; 3) Irradiate with ultraviolet light for 0.5-30 minutes to initiate a polymerization reaction, so that liquid crystals and azo dyes form microdroplets and distribute in the polymer to prepare a flexible solar thermal insulation liquid crystal polymer film.