Organic reversible thermochromic microcapsule with long service life and large color difference and preparation method thereof

Abstract

The invention discloses an organic reversible thermochromic microcapsule with long service life and large color difference and a preparation method thereof. A wall material of the organic reversible thermochromic microcapsule is prepared from the following raw materials in percentage by weight through polymerization: 30-95% of acrylate and / or methacrylate, 5-70% of a divinyl and / or polyvinyl monomer mixture, and 0-10% of an acrylic acid and / or methacrylic acid mixture, and a core material is composed of a colour former 3,3-di(4-dimethylaminophenyl)-6-dimethylamino phthalide, a color developing agent 4,4'-dihydroxydiphenylsulfone, and a solvent selected from 1-dodecanol, 1-tetradecanol, 1-hexadecanol and 1-octadecanol; and the preparation method is implemented through carrying out prepolymerization on monomers and carrying out suspension polymerization on the obtained product. The obtained organic reversible thermochromic microcapsule has the advantages of long service life and large color difference; the microcapsule does not release formaldehyde, and does not contain bisphenol A, so that the microcapsule is safer to use.

Description

technical field [0001] The invention relates to an organic reversible thermochromic microcapsule and a preparation method thereof, in particular to an organic reversible thermochromic microcapsule of an acrylate-based wall material and a preparation method thereof, and belongs to the field of fine chemicals. Background technique [0002] Organic reversible thermochromic material refers to a functional material that can change color when the temperature is higher or lower than a specific temperature, and has a memory function and can be used repeatedly. Organic reversible thermochromic materials based on the mechanism of electron gain and loss are generally composed of a chromogenic agent, a chromogenic agent, and a solvent. The chromogenic agent determines the color of the color-changing material system, and the color depth is mainly determined by the chromogenic agent. The effect of system discoloration temperature. [0003] Because the organic reversible thermochromic com...

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Problems solved by technology

[0003] Because the organic reversible thermochromic compound composed of electron donor dyes has bright colors, sensitive discoloration, and lower price than liquid crystal materials, it has been used in textile printing and dyeing, printing ink, anti-counterfeiting, temperature-indicating materials, and coatings. Its main disadvantage is that when the color changes, the solvent in it will change from solid to liquid or from liquid to solid, so it is easily affected by the environment. When encountering strong acid, it will lose the reversibility of discoloration. It will react with weakly acidic chromogenic agents, and will also lose the reversibility of discoloration, and may be dissolved in some organic solvents, so it is required to isolate the organic reversible thermochromic compound from the use environment, a method of isolating It is to use polymer materials to wrap organic reversible thermochromic materials to obtain microcapsules containing organic reversible thermochromic materials. This preparation process is also called microencapsulation. Organic reversible thermochromic compounds in microcapsules are called As the core material, the polymer material wrapped around the core material is called the wall material, which requires the wall material to be resistant to strong acids and alkalis and organic solvents, not easy to degrade, the wall material is transparent, and the light absorption rate is low, which can prevent discoloration of organic reversible thermochromic materials The impact of sharpness and vividness

[0004] There are many documents on the preparation of organic reversible thermochromic microcapsules, but there are not many types of wall materials. Chinese patent CN102477290 discloses a thermosensitive color-changing material microcapsule and its preparation method. The raw material of the wall material is melamine resin prepolymer. Chinese patent The wall material disclosed in CN102807853 is a wall covering system formed by styrene-maleic anhydride copolymer and urea-formaldehyde resin prepolymer. Although urea-formaldehyde resin honey and melamine resin have good sealing performance, their light transmittance is poor, resulting in urea-formaldehyde resin Organic reversible thermochromic material microcapsules made of resin and melamine resin as the wall material have small color difference when the color changes; due to the incompatibility of urea-formaldehyde resin or melamine resin with the thermochromic compound, the organic reversible thermal The color-changing microcapsules will quickly lose their color-changing properties after experiencing temperature changes, and their service life is short; in addition, whether it is urea-formaldehyde resin or melamine resin, formaldehyde may be released during use, and formaldehyde is a recognized carcinogen; other common The wall material has gelatin. Although the light transmission of gelatin is better than that of urea-formaldehyde resin and melamine resin, but limited by the nature of gelatin, its stability is poor and it is easy to degrade

Most of the existing organic reversible thermochromic compounds based on the electron gain and loss mechanism use bisphenol A as the chromogenic agent. Bisphenol A is an endocrine disruptor, and its accumulation in nature and the environment will cause serious environmental and ecological problems.

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