Method for beaching shellac using chlorine dioxide and alcohol solvent, and application thereof

A technology for bleaching shellac and alcohol solvents, which is applied in the direction of applications, medical preparations of non-active ingredients, pharmaceutical formulas, etc. It can solve the problems of prolonging the bleaching time, affecting the bleaching efficiency, and short product life, so as to improve the bleaching efficiency. The effect of increasing the application range and improving stability

Inactive Publication Date: 2012-04-11
KUNMING UNIV OF SCI & TECH
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, this technology has high requirements on the control accuracy of the pH value of the colloid analysis. If the pH value of the colloid analysis is too high, it will increase the consumption of shellac and increase the difficulty of subsequent dehydration. If the pH value of the colloid analysis is too low, the product life will be shorter.
The third type of technology represented by Chinese patent application (92105048.8) uses sodium chlorate to bleach shellac in an ethanol system. The mild condition also reduces the bleaching temperature at the same time, and the mildness of the bleaching condition makes the color index of the bleached shellac low and the thermal stability improved, but the problem is that the used bleaching agent sodium chlorate
[0007] The low solubility in ethanol affects the bleaching efficiency of the system and prolongs the bleaching time

Method used

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  • Method for beaching shellac using chlorine dioxide and alcohol solvent, and application thereof
  • Method for beaching shellac using chlorine dioxide and alcohol solvent, and application thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0024] Take 100g of purple film (commercially available grade A purple film, the color is purple-red, color index ≤18) and 300g of absolute ethanol are mixed, the constant temperature water bath is heated to 65 ℃, the mixture is put into the water bath and fully stirred to obtain a mass ratio of 1:3 lac ethanol solution, add 210mL chlorine dioxide (commercially available industrial product), the available chlorine content is 10g / L, control the pH between 4.0-6.0 during the bleaching process, stir and bleach at 65℃ for 2h to obtain bleaching Glue solution, add dilute sulfuric acid with a mass percentage of 5% to the bleached glue solution, adjust the pH of the bleached glue solution to 3, and make the bleached shellac precipitate flocculent, and then repeatedly rinse with water to precipitate the shellac to wash water After the pH value is 7, filter and dry at room temperature for more than 7 days to obtain bleached shellac with dark yellow color and the absorbance of ethanol sol...

Embodiment 2

[0026] Take 100g of purple film (commercially available grade A purple film, the color is purple, color index ≤18) and 500g of absolute ethanol are mixed, the constant temperature water bath is heated to 70 ℃, the mixture is put into the water bath and fully stirred to obtain a mass ratio of 1:5 methanol solution of shellac, add 420mL chlorine dioxide (commercially available industrial product), the available chlorine content is 20g / L, control the pH between 4.0-6.0 during the bleaching process, stir and bleach at 70℃ for 4h to obtain bleaching Glue solution, add 3% dilute sulfuric acid to the bleaching glue solution to adjust the pH of the bleaching glue solution to 4, so that the bleached shellac will precipitate out in a flocculent state, and then repeatedly rinse with water to precipitate shellac to the pH value of the washing water After it is 7, filter dry and dry at room temperature for more than 7 days to obtain bleached shellac with yellow color. E 490 It is 11.3% of th...

Embodiment 3

[0028] Take 100g of purple film (commercially available grade A purple film, the color is purple, color index ≤18) and 200g of absolute ethanol are mixed, the constant temperature water bath is heated to 80 ℃, the mixture is put in the water bath and fully stirred to make the mass ratio 1:2 lac ethanol solution, add 595mL chlorine dioxide (commercially available industrial product), the available chlorine content is 20g / L, control the pH between 4.0-7.0 during the bleaching process, stir and bleach at 80℃ for 1h to obtain bleaching Glue solution, add 10% dilute sulfuric acid to the bleaching glue solution to adjust the pH of the bleaching glue solution to 2, so that the bleached shellac will precipitate out in flocs, and then repeatedly rinse with water to precipitate the shellac to the pH value of the washing water After it is 7, filter and dry at room temperature for more than 7 days to obtain bleached shellac with light yellow color. E 490 It is 9.6% of the original purple fi...

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Abstract

The invention discloses a method for beaching shellac using chlorine dioxide and an alcohol solvent. The method comprises the following steps of: dissolving shellac using the alcohol solvent into solution, adding chlorine dioxide to the solution under the condition of constant temperature and stirring the solution for bleaching for certain time, thereby obtaining bleached shellac solution; adding dilute sulphuric acid to the bleached shellac solution so that the bleached shellac is separated out, and then repeatedly washing the bleached shellac until the pH of washing water is neutral; and drying the shellac at the room temperature, thus obtaining the bleached shellac, wherein the absorbance of the ethanol solution in the position of 490 nm can be reduced to 1.6% of the raw material shellac, while the color index thereof can be reduced to be less than 0.5#; and other technical indexes are capable of meeting the requirements of the refined bleached shellac level I. The method is characterized in that: bleaching conditions are mild; a non-alkaline condition is adopted; the bleaching temperature is low; the dosage of an acidic precipitator is low; the color index of the obtained bleached shellac is low; and accurate control and regulation can be performed by adjusting the dosage of the chlorine dioxide, etc; therefore, the application of the bleached shellac in special fields can be extended.

Description

Technical field [0001] The invention relates to a method for bleaching shellac with chlorohydrin solvents and its application. Background technique [0002] Shellac is also called shellac. It is a purple-red colloid secreted by lac insects parasitic on the host plant after absorbing the sap. It is a natural condensate formed by components such as tungoleic acid and shellac. Because of its brownish-red color, film-forming properties and water vapor permeability, it is often used to extract natural pigments, make furniture paints and insulating materials. [0003] Shellac contains slightly different components depending on the place of production, but usually contains about 67.9% of C, 9.1% of H and 23.0% of O, and its molecular formula meets the empirical formula (C 4 H 6 O) n , The relative molecular mass of fresh shellac (uncured shellac) is about 1000, so it can be inferred that the value of n in the molecular formula of shellac is about 15, generally 6-22. On averag...

Claims

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Application Information

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IPC IPC(8): C09F1/02A23B7/16A23G3/54A61K8/98A61K47/46
Inventor 唐辉黄喜坚张晓春
Owner KUNMING UNIV OF SCI & TECH
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