Orange thermal-sensitive colorant and preparation method thereof

Abstract

The present invention aims to disclose an orange thermal colorant and a preparation method thereof. The orange thermal colorant is 3-dibutylamino-7-ethoxyacylfluoran. Compared with the prior art, the reaction raw materials are readily available, the production process is simple, and the product is stable. Not only can orange thermal paper, film, and thermal color-forming materials be produced, but also thermal color-forming materials of any color can be produced by color matching, thereby achieving the purpose of the present invention.

Description

Technical Field

[0001] The present invention relates to a thermosensitive colorant and a preparation method thereof, in particular to an orange thermosensitive colorant and a preparation method thereof. Background Art

[0002] Currently, thermal printing is widely used in many industries due to its simplicity and convenience.

[0003] Thermal colorants are special compounds that, unlike traditional dyes, are inherently colorless. When applied or distributed on various substrates, such as paper, plastic film, metal film, textiles, and solvents, they react chemically with thermal developers under the influence of heat, pressure, and additives to produce colored compounds, achieving color development. These compounds are used in the production of thermal and pressure-sensitive paper, color-shifting coatings, and are widely used in a variety of applications, including labels, fax machines, receipts, documents, color-shifting coatings, and writing materials.

[0004] Existing heat-sensitive couplers that produce orange color are rare. Existing orange heat-sensitive couplers include 3-cyclohexylamino-6-chlorofluoran and 3-diethylamino-6,8-dimethylfluoran. However, the raw materials for these orange heat-sensitive couplers are difficult to obtain, resulting in high production costs, poor product color, unstable color development, and a tendency to prematurely colorize.

[0005] Therefore, there is a particular need for an orange thermosensitive coloring agent and a preparation method thereof, which can print all colors required by users to solve the above-mentioned existing problems. Summary of the Invention

[0006] The object of the present invention is to provide an orange thermosensitive color-forming agent and a preparation method thereof, which addresses the deficiencies of the prior art and has readily available raw materials, a simple process, low production cost, stable product and bright color.

[0007] The technical problem solved by the present invention can be achieved by adopting the following technical solutions:

[0008] In a first aspect, the present invention provides an orange thermal coupler, wherein the orange thermal coupler is 3-dibutylamino-7-ethoxyacylfluoran, and its molecular formula is as follows:

[0009]

[0010] In a second aspect, the present invention provides a method for preparing an orange thermosensitive coupler, comprising the following steps:

[0011] Dissolve dibutyl benzoic acid in concentrated sulfuric acid, stir and dissolve, add ethyl p-hydroxybenzoate or ethyl p-methoxybenzoate, condense and then precipitate, neutralize, perform ring-closure reaction under alkaline conditions, decolorize with activated carbon, cool and crystallize, and dry to obtain the finished product.

[0012] In a preferred embodiment of the present invention, the ratio of concentrated sulfuric acid to dibutyl benzoic acid is 2-8:1, preferably 4-6:1; and the concentration of concentrated sulfuric acid is 90-110%, preferably 100-105%.

[0013] In a preferred embodiment of the present invention, the temperature of the condensation reaction is 5-50°C, and optimally 10-30°C.

[0014] In a preferred embodiment of the present invention, the molar ratio of dibutyl benzoic acid to ethyl p-hydroxybenzoate or ethyl p-methoxybenzoate is 1.0-1.5:1, and optimally 1.05-1.2:1.

[0015] In a preferred embodiment of the present invention, the ring-closure reaction is carried out under alkaline conditions in the presence or absence of a solvent, and the temperature of the ring-closure reaction is 60-100°C, and optimally 80-90°C.

[0016] Furthermore, the solvent is benzene, toluene, ethanol or methanol.

[0017] Compared with the prior art, the orange thermal colorant and preparation method of the present invention have readily available reaction raw materials, a simple production process, and a stable product. Not only can orange thermal paper, film, and thermal color-forming materials be produced, but also thermal color-forming materials of any color can be produced by color matching, thereby achieving the purpose of the present invention.

[0018] The features of the present invention can be clearly understood by referring to the detailed description of the preferred embodiments below. DETAILED DESCRIPTION

[0019] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is further explained below in combination with specific details.

[0020] The orange thermal coupler of the present invention is 3-dibutylamino-7-ethoxyacylfluoran, and its molecular formula is as follows:

[0021]

[0022] Example 1

[0023] In a 1000ml three-necked flask, add 200g of concentrated sulfuric acid and 100g of fuming sulfuric acid, add 100g of dibutyl benzoic acid at 30-40℃, stir and dissolve after addition, cool to below 10℃, slowly add 56g of ethyl p-hydroxybenzoate at 10-20℃, keep warm at 15-20℃ for 24 hours after addition, add 1000g of ice water, stir for 1 hour, filter, add the filter cake to 200ml of water, add 500ml of toluene, neutralize with sodium carbonate while stirring to pH>9, reflux for 3 hours, separate the water layer, wash the organic phase with water until neutral, add 5g of activated carbon, reflux for dehydration, filter the activated carbon, cool and crystallize, filter and dry to obtain 90g of the finished product.

[0024] Example 2

[0025] In a 1000ml three-necked flask, add 200g of concentrated sulfuric acid and 100g of fuming sulfuric acid, add 100g of dibutyl benzoic acid at 30-40℃, stir and dissolve after addition, cool to below 10℃, slowly add 68g of ethyl p-methoxybenzoate at 10-2℃, keep warm at 15-20℃ for 24 hours after addition, add 1000g of ice water, stir for 1 hour, filter, add the filter cake to 200ml of water, add 500ml of toluene, neutralize with sodium carbonate while stirring to pH>9, reflux for 3 hours, separate the water layer, wash the organic phase with water until neutral, add 5g of activated carbon, reflux for dehydration, filter the activated carbon, cool and crystallize, filter and dry to obtain 102g of the finished product.

[0026] Example 3

[0027] In a 1000ml three-necked flask, add 400g of concentrated sulfuric acid, add 100g of dibutyl benzoic acid at 30-40℃, stir and dissolve after addition, cool to below 10℃, slowly add 68g of ethyl p-methoxybenzoate at 10-20℃, keep warm at 25-30℃ for 32 hours after addition, add 1000g of ice water, stir for 1 hour, filter, add the filter cake into 200ml of water, add 500ml of toluene, neutralize with sodium carbonate while stirring to pH>9, reflux for 3 hours, separate the water layer, wash the organic phase with water until neutral, add 5g of activated carbon, reflux for dehydration, filter the activated carbon, cool and crystallize, filter and dry to obtain 98g of the finished product.

[0028] Example 4

[0029] In a 1000ml three-necked flask, add 300g of concentrated sulfuric acid and 100g of fuming sulfuric acid, add 100g of dibutyl benzoic acid at 30-40℃, stir to dissolve after addition, cool to below 10℃, slowly add 65g of ethyl p-methoxybenzoate at 5-10℃, keep warm at 10-15℃ for 32 hours after addition, add 1000g of ice water, stir for 1 hour, filter, add the filter cake to 200ml of water, add 500ml of toluene, neutralize with sodium carbonate while stirring to pH>9, reflux for 3 hours, separate the water layer, wash the organic phase with water until neutral, add 5g of activated carbon, reflux for dehydration, filter the activated carbon, cool and crystallize, filter and dry to obtain 105g of the finished product.

[0030] Thermal coating experiment:

[0031] 10 g of the product was mixed with 20 g of 10% PVA solution, 0.5 g of emulsifier (sodium acrylate) was added, and the mixture was ground into an emulsion with a particle size of 0.8 μm using a ball mill.

[0032] 15 g of bisphenol S and 30 g of 10% PVA were mixed, 1.0 g of emulsifier (sodium acrylate) was added, and the mixture was ground with a ball mill to an emulsion with a particle size of 1.0 μm.

[0033] Mix the above two emulsions at 6g / m 2 The coating amount is applied on the paper, and the thermal paper begins to emit orange statically when heated to 80 degrees.

[0034] The basic principles, main features and advantages of the present invention are shown and described above. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention, which is defined by the appended claims and their equivalents.

Claims

1. Application of 3-dibutylamino-7-ethoxyacylfluoran as an orange thermal coupler. The molecular formula of the 3-dibutylamino-7-ethoxyacylfluoran is as follows:

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