JPS59122565A - Thermochromic ink composition - Google Patents

Abstract

PURPOSE:A thermochromic ink that contains the leuko-form of a basic dye and molecular sulfur, thus it is coated on the surface of rubber articles and shows that vulcanization is over by changing its color, when the temperature reaches the operation level. CONSTITUTION:The leuko-form of a basic dye such as leuko malachite green, preferably 2-10wt%, molecular sulfur, preferably 10-20wt%, further preferably, a water-soluble or dispersible resin or polymer such as PVA, 5-10wt%, and the rest part of solvent, preferably not dissolving the leuko dye and the molecular sulfur are added to give the objective ink. USE:It is also useful in judging the completion of sterilization of surgical operation tools and packed food products.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermochromic ink that changes color under certain heating conditions, particularly when vulcanization conditions are reached when vulcanizing rubber, when sterilization conditions are reached when heat sterilized, or Concerning thermochromic inks that change color and display when certain industrial heating conditions are reached. Conventionally, when vulcanizing rubber, the vulcanization temperature and vulcanization time are set, and vulcanization is achieved by heating at a certain temperature for a certain period of time. I had hemorrhoids. However, the temperature distribution within the vulcanization chamber is not necessarily uniform;
In addition, since the appearance of the rubber hardly changes during vulcanization, it is difficult to confirm, resulting in defective products due to insufficient vulcanization or over vulcanization, resulting in product loss, laborious inspections, and unnecessary energy consumption. It had the disadvantage of being consumed.

This invention solves the above-mentioned drawbacks, and if it is applied to the surface of a rubber molded product before vulcanization, it will change color when the set vulcanization conditions are met, making it easy to confirm the completion of vulcanization. The present invention relates to a thermochromic ink composition that can be used as a thermochromic ink composition.

In addition, in the sterilization of surgical tools, food bags, etc., the same method can be used to clearly indicate the criteria for determining whether sterilization has been completed or not.

This ink composition can be used in various marking methods in the form of writing instrument ink, stamp ink, and printing ink.

This invention applies the principle that when the leuco form of a basic dye and molecular sulfur are mixed and dispersed and heated, the sulfur melts, opens the ring, and reacts with the leuco form to develop color.

leucoindigo, leucocrystal violet,
Examples include leuco forms of basic dyes such as acetyl leucomethylene blue, benzoyl leucomethylene blue, p-chlorobenzoyl methylene blue, or 3,4-dichlorobenzoyl leucomethylene blue.

The essential components of this invention are the leuco basic dye and molecular sulfur, but in order to form an ink composition, these two components must be mixed and dispersed in a vehicle. Next, the components forming the vehicle will be described. Water-soluble or water-dispersible resins, resins or polymers forming the vehicle include:
Polyvinyl alcohol, polyvinyl pyrrolidone, polyethylene oxide, carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose, resins such as sodium polyacrylate, processed starch products such as starch or dextrin, water-soluble polyethylene emulsion, water fi
Examples include aqueous emulsions of synthetic resins such as polyurethane emulsions and water-soluble polyacrylic emulsions, and these resins or polymers can be used without particular limitation as long as they are water-soluble or water-dispersible.

The solvent that forms the vehicle must be able to dissolve or disperse the resin and polymer and be insoluble in the leuco form of the basic dye and molecular sulfur, and must be water alone or a mixture of water-soluble organic solvents containing water as the main component. A solvent is used.

Water-soluble organic solvents are added to adjust the viscosity and drying rate of ink compositions, or to increase the solubility of resins, and are added to aliphatic solvents such as methanol, ethanol, isopropanol, etc.
Polyhydric alcohols such as ethylene glycol, diethylene glycol, and glycerin of diethylene glycol are used.

However, when adding these organic solvents, care must be taken not to dissolve leuco bodies and molecular sulfur.

In addition to the above-mentioned components, conventional dyes and pigments are used to control the color development of the ink, and surfactants, preservatives, fragrances, and the like may be added to ensure good application of the ink composition to the surface to be coated.

The ink composition of the present invention contains 1 leuco form of basic dye per 100 parts by weight of ink (hereinafter "parts by weight" is simply referred to as "parts").
-15 parts, preferably 2 to IO parts, molecular sulfur is usually 2 to 5 times the leuco form, 5 to 80 parts, preferably 10 to 20 parts.
parts, the resin or polymer is 2 to 20 parts, preferably 5 to 10 parts, and the solvent is added to make a total of 100 parts.

If the leuco form of the basic dye is less than 1 part, the color development will be indistinct, and if it exceeds 15 parts, a large amount of molecular sulfur will be required, resulting in an inappropriate viscosity of the ink composition and indistinct discoloration. If the molecular sulfur content is less than 5 parts, the color development of the leuco body will be incomplete, and if it exceeds 30 parts, the viscosity will be inappropriate.

The ink composition of the present invention includes a low viscosity composition such as a writing instrument ink, a medium viscosity composition such as a stamping ink, a high viscosity composition such as a printing ink, and a composition having a wide range of viscosity. The ratio of the components must be adjusted accordingly depending on the desired viscosity.

To prepare the composition of the present invention, the resin or polymer is dissolved in a solvent, and if necessary, a surfactant, preservative, or fragrance is added thereto to form a vehicle. To this vehicle, add the leuco form of basic dye, molecular sulfur, and if necessary solid content such as pigment, mix thoroughly using a stirrer or triple roll, etc., and prepare an ink composition, or mix the leuco form and sulfur. When the particle size and difficulty of pulverization are different, there is a method of separately mixing and pulverizing the leuco body and the vehicle, and the sulfur and the vehicle, and then mixing the two.

Next, examples will be described to further clarify the invention.

Example 1 Ai: 5 parts of polyvinyl alcohol (Riorebovar PVA-117 manufactured by Kuraray) and water
In addition to 80 parts, the heating loss at room temperature is A,
to completely dissolve and disperse. 15 parts of titanium oxide and 2 parts of leuco crystal violet are added to this vehicle and thoroughly mixed and stirred.

Part B Polyvinyl alcohol 5 parts water
Prepare a vehicle using 90 parts in the same manner as above, add molecular sulfur, and mix and stir.

Combine A liquid and B liquid and further mix. The coating film of this ink turned colorless to dark blue by heating at 180'C for 5 seconds.

Example 2 To 10 parts of polyvinyl alcohol and 7 parts of acrylic acid emulsion, 85 parts of water (Mobiny #761 manufactured by Hekinuto Synthesis Co., Ltd.) was added and stirred thoroughly until the polyvinyl alcohol was completely dissolved to form a vehicle.Molecular sulfur 15 parts benzoyl Four parts of leucomethylene blue were added and further stirred and mixed to obtain an ink from which a water-resistant coating film was obtained. When this 11-liter coat of ink is heated at 20°C for 10 minutes, the color changes from colorless (almost colorless to light yellow) to blue. Procedural Amendment April 118, 1981 Kazuo Wakasugi, Commissioner of the Patent Office 1. Indication of the case: 1982 Patent No. 4M No. 229440 2, Name of the invention: Thermochromic ink composition 3, Person making the correction: Postal code: 537 Telephone number: 06-972-12414;
Date of the amendment order: March 9, 1982 5. Item 6 of the application to be amended and the title of the invention in the specification. Contents of the amendment (11) The amended application will be resubmitted.

(2) Title of invention in the specification "Thermochromic ink" Corrected to ``thermochromic ink composition.''

Claims (1)

[Claims] A thermochromic ink composition comprising a leuco basic dye and molecular sulfur.