RU2138530C1 - Composition for manufacturing thermal indicator coating - Google Patents

Abstract

FIELD: thermosensitive materials. SUBSTANCE: invention is designed for color indication of solids, for example, for identifying precious papers or articles provided with dye-labeled tag. Composition contains (in wt %) thermosensitive substances, amide-containing acryl resin (1.5-15), butanol (40-60), and ethylacetate (20-40), said thermosensitive substances being 1-hexadecanol (0.5-7), 4-ethylphenol (0.5-5), and, additionally, melamine-formaldehyde resin (1-10). EFFECT: increased visualization quality. 3 cl

Description

 The invention relates to compositions for obtaining a thermal indicator coating and can be used for color indication of the temperature of solids, for example, for identifying a security or a product equipped with a label (tag) with a label from the aforementioned paint.

 A known composition for obtaining a thermal indicator coating containing thermosensitive substances, amide-containing acrylic resin, butanol and ethyl acetate. Moreover, as heat-sensitive substances, it contains cholesterol esters, for example, cholesterylpelargonate, cholesteryl valerate and cholesteryl oleate (Russian patent N 1354697, CL C 09 D 5/26, 1981 - prototype).

 Such a composition makes it possible to obtain sufficiently thin and uniform coatings with a high intensity of selective reflection, including in the temperature range of the human body. Nevertheless, it is not without drawbacks, which primarily include its rather high cost due to the high cost of the mentioned cholesterol esters (see, for example, "Janssen chimica" - catalog handbooc of fine chemicals for research and industry, 1993-1994) . At the same time, attempts to incorporate cheaper thermosensitive substances into the same polymer matrix — an amide-containing acrylic resin — did not lead to the desired results.

The basis of the invention is the task of creating a composition for obtaining a thermal indicator coating, which, thanks to the use of cheaper low molecular weight thermosensitive substances and a polymer matrix, modified so as to enable the inclusion of the above thermosensitive substances, would be inexpensive and at the same time consistent with the main technical requirements for such compositions, including the ability to obtain uniform coatings with high intensity of mudflow tive reflection (color brightness) including the human body temperature range (not lower than 31 ^o C), possessing sufficient strength with a relatively small thickness.

The problem is solved in that the composition for obtaining a thermo-indicator coating containing thermosensitive substances, an amide-containing acrylic resin, butanol and ethyl acetate, according to the invention contains 1-hexadecanol and 4-ethyl phenol as heat-sensitive substances and additionally contains melamine-formaldehyde resin in the following ratio of components, wt. %:
1-hexadecanol - 0.5-7.0
4-Ethylphenol - 0.5-5.0
Amide-containing acrylic resin - 1.5-15.0
Melamine formaldehyde resin - 1-10
Butanol - 40-60
Ethyl Acetate - 20-40
The temperature of 31 ^o C was chosen as the minimum acceptable for visualization of the temperature transition, since it is, on the one hand, the average temperature of human skin under normal conditions, and on the other hand, is a temperature that is rarely higher than air temperature in the warm season. This temperature provides a composition with a lower limit of the content of 4-ethylphenol (0.5 wt.%), Having a melting point of 42-45 ^o C. The upper limit of the content of this substance (5 wt.%) With a lower limit of the content of 1-hexadecanol (0, 5 wt.%), Having a melting point of 48-50 ^o C, provides visualization of the transition through a temperature of about 42 ^o C, which is necessary for the use of the composition in countries with hot climates.

The composition for obtaining a thermal indicator coating in General is obtained as follows. Acrylic and melamine-formaldehyde resins are added to the mixture of solvents - butanol and ethyl acetate (specific amounts of all components are given below in the table). To the resulting solution was added 1-hexadecanol and 4-ethylphenol. Stirred and applied to the surface of the label (label) in the form of a round, oval or other form of spots with an area of 1-5 cm ² . Dried at a temperature of 50-60 ^o C to dry completely.

 As a result of the above actions, a so-called “identification tag” is formed on the surface of the label, which is a copolymer of melamine-formaldehyde resin and acrylate having a mesh structure, in the cells of which thermosensitive substances - 1-hexanol and 4-ethyl phenol are included.

 To obtain a “label” of various coloring, various pigments can be added to it, the color of which is determined by aesthetic (consumer's taste) or technical (base color - in this case labels - under the “label”) conditions. In any case, whether the “label” will be colored or not, it becomes transparent or almost transparent upon thermal exposure, that is, it “disappears”. So, for example, a white “label” applied to a blue label when exposed to a specific temperature by a heat field becomes “blue” because the blue field of the label appears underneath. Changing the ratio of thermosensitive substances in this composition, you can visualize a different temperature transition (see table).

 All the compositional options described in the table make it possible to obtain a coating of sufficient strength with a relatively small thickness. Moreover, they have a high intensity of selective reflection (color brightness). Nevertheless, it should be noted that with a decrease in the proportion of resins with respect to the proportion of thermosensitive substances, the thickness of the resulting coating decreases, and hence its strength. In addition, this leads to a relative decrease in the intensity of selective reflection, since the cells of the resulting copolymer are apparently not enough to include the entire amount of heat-sensitive substances in them (option No. 4).

 On the other hand, a decrease in the fraction of heat-sensitive substances with respect to the fraction of resins also leads to a decrease in the intensity of selective reflection (brightness). The coating in this case turns out to be excessively thick, which in turn also reduces the intensity of selective reflection (option N 6).

 It should also be noted that the quality of the coating and the intensity of selective reflection are affected by the unbalanced portions of the resins, which is also obviously associated with a deterioration in the structural characteristics of the copolymer formed as a result of the modification of the melamine-formaldehyde resin (options NN 7 and 8). Finally, it must be borne in mind that with an increase in the proportion of amide-containing acrylic resin, the proportion of the most acceptable solvent for it, ethyl acetate, should also increase.

The value of the mentioned temperature transition can determine the source of the thermal field, which affects the "label". So, at a temperature of the order of 31-36 ^o C, a person’s hand (finger) is a convenient source of thermal field. At a higher temperature, the flame of a match, cigarette, etc. can be used as the indicated source.

 The described composition, as can be seen from the presented examples, will allow to obtain high-quality thermal indicator coatings, the cost of which is at least 5-10 times lower than the cost of coatings obtained using a known composition.

Claims (1)

Composition for producing a thermo-indicator coating containing thermosensitive substances, an amide-containing acrylic resin, butanol and ethyl acetate, characterized in that it contains 1-hexadecanol and 4-ethyl phenol and additionally contains melamine-formaldehyde resin in the following ratio of components, wt.%:
1-hexadecanol - 0.5 - 7.0
4-Ethylphenol - 0.5 - 5.0
Amide-containing acrylic resin - 1.5 - 15.0
Melamine formaldehyde resin - 1 - 10
Butanol - 40-60
Ethyl Acetate - 20 - 40

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