JP2002019257A - Plastic container printed by temperature indicating ink and method for printing plastic container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plastic container capable of improving toy properties, exquisiteness by discoloring, unexpectedness, design effect and the like by printing a temperature indicating ink directly on a surface of the container so that the print is discolored by a temperature change. SOLUTION: A method for printing the plastic container comprises the step of printing the container directly with the temperature indicating ink. The plastic container is printed by the temperature indicating ink. The used temperature indicating ink preferably contains, in the case of ultraviolet curing type, a photopolymerization initiator of 0 to 20 pts., a photosensitizer of 0 to 20 pts. and a temperature indicating pigment of 1 to 50 pts. with respect to a vehicle of 100 pts. In the case of the ink of the ultraviolet curing type, the method also comprises the steps of, in the case of the ultraviolet curing type of the indicating ink, printing a printing ink containing an ultraviolet curing type ink composition as a base, and then emitting the ultraviolet ray to the printing surface to cure the ultraviolet curable component of the ink.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic container on which a temperature indicating ink is directly printed when displaying and decorating a plastic container, particularly a product name, a design, and the like, and a method for printing the plastic container.

[0002]

2. Description of the Related Art Conventionally, a thermometer has been used to measure the temperature of the contents of a container. On the other hand, the temperature indicating ink captures a change in temperature as a change in color. Although the accuracy of temperature indicating inks is generally inferior to other measurement methods, temperature measurement can be easily performed without using special instruments, and the temperature distribution of places, planes, and three-dimensional objects that cannot be measured by other methods. You can also know. At present, reversible temperature indicating inks put into practical use include a metal complex salt type, a cholesteric liquid crystal type, and a metamocolor type.

[0003]

Recently, there is a demand for plastic containers to be differentiated from others and to add commercial value, and in particular, functional printing is required.
By the way, it was troublesome to use a thermometer each time to know the temperature inside the container. The present invention solves such a problem, and directly prints with a temperature indicating ink on the surface of a plastic container or on the surface of the plastic container to form a plastic container that changes color due to a change in temperature. The purpose is to provide.

[0004]

Means for Solving the Problems The present invention relates to a plastic container printed with a temperature indicating ink and a printing method thereof.

[0005] It is particularly preferred that the temperature indicating ink is of an ultraviolet curable type. Further, the ink of the present invention may be an alkali-releasing ink as described in, for example, Japanese Patent No. 2989935 and Japanese Patent No. 2999334 so that the container and the printed portion can be separated after recovery. Good.

As a means for printing characters, patterns, figures, and the like on a plastic container with a temperature indicating ink, ordinary printing methods such as screen printing, gravure printing, flexographic printing, and offset printing are used. preferable. For screen printing, 1
A silk screen version of about 00 to 420 mesh is preferable.

[0007] The temperature indicating ink used in the present invention is:
In the case of an ultraviolet curing type, 0 to 20 parts of a photopolymerization initiator, 0 to 20 parts of a photosensitizer, and 1 to 1 part of a temperature pigment are added to 100 parts of a vehicle.
Particularly preferred is 50 parts.

In the printing method of the present invention, printing may be performed without treating the surface of the plastic container prior to printing. However, the surface of the plastic container may be subjected to a treatment such as a frame or corona discharge, or an anchor coat treatment. You may do.

[0009] The material of the plastic container is not particularly limited, and many kinds of resins such as polyvinyl chloride, polystyrene, acryl, polyester and polyolefin are used. The plastic according to the present invention can contain additives such as a colorant, an ultraviolet absorber, and an antistatic agent at an appropriate ratio, if necessary.

In the case where the temperature indicating ink used in the present invention is an ultraviolet-curing type, the printing method is to perform printing with a printing ink based on an ultraviolet-curing ink composition when the ultraviolet-curing type is used. The printing surface is irradiated with ultraviolet rays to cure the ultraviolet curable components in the printing ink.

The plastic container of the present invention can be obtained by hollow molding, biaxial stretch blow molding, injection molding, or the like.

When the temperature indicating ink used in the present invention is of an ultraviolet curing type, many photopolymerization initiators are known. Examples thereof include benzophenone, diethoxyacetophenone, 1-hydroxycyclohexylphenylketone. 2-methyl- (4-methylthiophenyl) -2-morpholinopropan-1-one,
Benzoin alkyl ether, benzyl, benzyl dimethyl ketal, camphorquinone, 2-ethylanthraquinone, methyl benzoylbenzoate, 4-phenylbenzophenone, 3,3'-dimethyl-4-methoxybenzophenone, thioxanthone, 2,4-diethylthioxan Son, methylphenylglyoxylate, benzoylphosphine oxide, 1-trimethylbenzoyldiphenylphosphine oxide and the like. Examples of the photosensitizer include triethanolamine, methyldiethanolamine, triisopropanolamine, 4,4
'-Diethylaminobenzophenone, ethyl 4-dimethylaminobenzoate, 4-dimethylaminobenzoic acid-n-
Butoxyethyl and isoamyl 4-dimethylaminobenzoate.

Although the photopolymerization initiator can be used alone, it is often used in combination with a photosensitizer to improve photopolymerizability.
The most suitable photopolymerization initiator and photosensitizer are selected depending on the ink vehicle component used. The criterion is determined depending on the purpose, such as the curing speed, the presence or absence of coloring at the time of curing, the presence or absence of a pigment, and the intensity of odor after curing. The amount used is relative to the ink vehicle.
Although a photopolymerization initiator and a photosensitizer can be used in amounts of 1 to 20 parts, respectively, when used in a large amount, the curing speed is fast but the molecular weight does not increase, the strength of the cured film is lowered, and the odor is also not strong. The most desirable use range is 2 to 10 parts as a combined amount of both. In that case, the usage ratio of the photopolymerization initiator and the photosensitizer depends on the type and the component ratio of the vehicle component, and in the case of an ink to which a coloring pigment described below is added,
It is necessary to change the ratio of the two depending on the ultraviolet absorbing power specific to the pigment, and the ratio is not uniform. Pigments are roughly classified into organic pigments and inorganic pigments in terms of chemical composition, but are also classified into colored pigments and non-colored pigments (enrichment pigments) in terms of application. When it comes to UV curing, the category of application is more important.

In order to observe discoloration, colorless and transparent are preferred, but pigments may be used as long as they do not affect discoloration. Of the color pigments, the inorganic pigments include lead white, zinc white, zinc sulfide,
White pigments such as titanium dioxide, blue pigments such as ultramarine, navy blue and cobalt blue, green pigments such as chromium oxide, pyridian, and chrome green, graphite, titanium yellow, yellow iron oxide, molybdate orange, cadmium pigments, and red stalks And black pigments such as iron black, titanium black and carbon black; metal pigments such as aluminum powder and bronze; and pearl pigments such as mica. However, there are many inorganic pigments that must be avoided from the viewpoint of safety and hygiene, and harmless ones are selected from the above.
For organic pigments, monoazo, disazo, condensed azo,
Indanthrone type, indigo type, thioindigo type, quinacridone type, phthalocyanine type, dioxazine type, isoindolinone type, pyrrolopyrrole type, etc. can be used.According to the curing method called ultraviolet irradiation, light fastness with less fading It is desirable to select and use a pigment having a high degree.

In order to obtain good color development, a large amount of pigment is blended with a vehicle in which a small amount of a pigment dispersant is added, and a pulverization pressure is physically applied by utilizing the viscosity improvement caused by the oil absorption. An easy state is created, and sufficient kneading is performed by a general medium dispersing machine such as a ball mill or a roll mill in the color material industry. The thus obtained high-concentration pigment dispersion (toner) is replenished and adjusted with a deficient vehicle so as to obtain a predetermined pigment concentration at the time of ink formulation.

In the ink composition used in the present invention, the properties of the printing ink, such as viscosity, fluidity, and thixotropy, are maintained, the ink buildup is maintained and increased, shrinkage buffering during curing, surface matting, and slip property imparting. Various non-colored pigments (enrichment pigments) can be used for the purpose of improving the strength of the film.
Commonly used extender pigments include talc, kaolin,
Silica, precipitated barium sulfate, precipitated calcium carbonate,
Inorganic pigments such as alumina white and white carbon,
Waxes such as polyethylene wax, polypropylene wax, and polyfluorinated polyethylene wax, and fine powders of artificial and / or natural polymers such as polyamide resin, polyimide resin, melamine resin, benzoguanamine resin, cellulose, and collagen. The amount of these can be freely determined according to the purpose. In the ink composition of the present invention, in order to adjust the finished state of the cured film,
Leveling and / or antifoaming agents can be added.
Among these, various leveling agents and defoaming agents generally sold in the market are used after confirming by a test those which are well compatible with the vehicle component and can obtain surface smoothness. The type and amount used do not limit the content of the ink composition of the present invention, and may be appropriately determined. Usually, the total amount of the leveling agent and / or the antifoaming agent is 0.5 to 0.5% of the total ink amount. 5% by weight are used.

In addition, if necessary, an ultraviolet absorber, a wetting improver, an antioxidant and the like can be used.

As the temperature indicating ink, conventionally known inks are used, and reversible or irreversible inks are selected depending on the use and purpose. Examples of reversible temperature indicating inks include, for example,
As an inorganic compound-based pigment, iodide of a heavy metal such as Hg, Ag, Cu, Pb or a complex salt thereof is used as a pigment,
Some are made into ink by adding a vehicle. For example, those having a pigment composition of Ag ₂ HgI ₄ and Cu ₂ HgI ₄ change color at specific temperatures of 50 ° C. and 70 ° C., respectively, but the temperature can be set between 40 ° C. and 70 ° C. by a two-component mixed system. . Currently 40 ℃, 50 ℃, 60 ℃ for low temperature
130 ° C, 150 ° C, 1 ° C, 70 ° C and high temperature
70 ° C. is commercially available. In addition, the pink color of the cobalt chloride solution becomes blue when the temperature is increased, and the heavy metal halide and the chelate complex are reversibly discolored. As an organic compound, for example, as a condensed aromatic ring-substituted ethylene derivative, spiropyrans reversibly change from colorless to colored when heated and melted. Bianthrone and dixanthylene change colorless to green and colorless to dark blue-green, respectively. Liquid crystals are classified into, for example, three forms, nematic, smectic, and cholesteric. Of these, cholesteric liquid crystals are mainly used in response to temperature. Most of cholesteric liquid crystals are derivatives of cholesterol. The discoloration temperature depends on the type of liquid crystal and the mixing ratio, but the order of discoloration is red, orange, yellow, green, blue,
Although purple, the temperature range from red to green is small, and the temperature range from green to purple is large. Normally, it is preferable to make the background black to make the discoloration easy to see. Metamocolor is also used. Metamocolor is composed of three components, the electron-donating color-forming organic compound relates to the color, the electron-accepting compound relates to the concentration, and the polar organic compound relates to the color change temperature.

As the quasi-reversible temperature indicating ink, for example, Ni
And Co hexatetramine salts discolor at relatively low temperatures
However, in a humid atmosphere, crystallization water is taken in again to restore the color. So
Irreversible temperature indicating inks include 3 (NH₄)₂O ・ Fe₂
O₃・ 12MoO₃・ 19H₂O ⁵⁾, Co (AsO₄)₂(Pyr)₂. Ten
H₂O, (NH₄)₃H₆[Fe (MoO₄)₆]. 7H ₂O, CoSi
F₆, Co (C₆H₅O₇)₂, [Cu (Pyr)₂] (CN
S)₂, (NH₄) ₃VO₃, CoNH₄PO₄. H₂O, Cu
(OH)₂, [Co (NH₃)₅Cl] Cl₂, 3 (NH₄)
₂O. Al₂O₃. 12MoO₃. 19H₂O, (NH₄)₂U₂O
₇, [Cr (NH₃) ₅Cl] SiF₆, [Co (NH₃)₆H. P
₂O₇, CdCO₃, NH₄MnP₂O₇Are used. What
Note that these irreversible temperature indicating inks are always controlled by temperature control.
In places where monitoring is not possible or where visual
This is convenient because there is a record of the degree.

When the luminous ink used in the present invention is of an ultraviolet curable type, the irradiation of ultraviolet rays on the printing surface is usually performed by a high-pressure mercury lamp or a metal halide lamp having a wavelength of about 200 to 450 nm. And the integrated amount of ultraviolet light is 100 to 500 mj / cm.
² is preferred. Also, usually, in the case of electron beam irradiation,
The irradiation is performed at an irradiation amount of 100 KGy, and 30 to 60 KGy is preferable.

[0021]

EXAMPLE 1 A reversible temperature indicating ink whose temperature changes at 5 to 15 ° C. was prepared.
Using a mesh screen plate made of Tetron (registered trademark), screen printing was performed on an untreated polyethylene terephthalate container of carbonated drinking water, and a UV light of 200 mj / cm ² was irradiated with a 120 W / cm metal halide lamp to obtain a cured film. . When this container was cooled to 5 to 15 ° C., the color changed to a color, and the carbonated drinking water was almost ready for drinking. The optimum temperature range varies depending on the season, and is 7-8 in summer.
℃, 9-10 ℃ in spring and fall, 11-12 ℃ in winter,
In the case of a container that changes color in this range, it can be known whether or not the temperature is in accordance with the season.

Example 2 A reversible metamocolor thermometer ink whose temperature changes at a temperature of ° C.
Screen printing was performed on an untreated polyethylene terephthalate container for tea using a mesh screen plate made of Tetron, and irradiation with an integrated ultraviolet light amount of 200 mj / cm ² was performed using a 120 W / cm metal halide lamp to obtain a cured film. When this container was heated, it changed color and the tea was ready to be drunk.

Example 3 An irreversible temperature indicating ink whose temperature changes at ° C. was screen-printed on a non-treated polyethylene terephthalate container of a pharmaceutical container using a screen plate made of mesh tetron, and the integrated amount of ultraviolet light was 200 mj using a 120 W / cm metal halide lamp. / Cm ² to obtain a cured film.
When this container was heated, the color changed at 50 ° C. or higher, and then the temperature was raised to room temperature, but the color changed. From this,
This vessel was found to have been heated to 50 ° C. or higher.

[0024]

According to the printing of the plastic container of the present invention, compared to printing with an ink containing a general coloring pigment, a printed matter appears or disappears due to a change in temperature, so that practicality, toy properties, discoloration can be achieved. Can enhance the taste, unexpectedness, design effect, etc. For example, it is easy to see at a glance whether or not the temperature of soft drinks is suitable for drinking, and use a temperature-measuring ink whose color appears or disappears at around 42 ° C, especially for plastic containers used in bathrooms. Thus, the degree of hot water can be easily known, and since the elephant by printing appears or disappears due to a change in the temperature of the bathroom, it has a toy property. There are three types of reversible temperature indicating inks: metal complex salts, cholesteric liquid crystals, and metamocolor. The metal complex salts are extremely excellent in light resistance and are therefore suitable for outdoor use. Further, the cholesteric liquid crystal system has a high discoloration accuracy, and thus is most suitable for medical use and other applications in which the temperature distribution is known. A fantasy color that changes one after another is suitable as a container for decoration. The metamocolor system can be freely selected for its color type and discoloration temperature, and changes colorfully, so that it can be used as a container for household daily necessities, a container for decoration, a container for toys, and the like. For example, for containers related to cold chains, -1
Discolored at 8 ° C, in the case of containers related to chilled foods, discolored at -5 to 5 ° C, in containers related to cold drinks, discolored at 5 to 10 ° C, temperature related In the case of containers, those that change color at 0 to 35 ° C., in the case of containers related to room temperature and air conditioning, those that change color in 10 to 30 ° C., and in the case of containers that change with body temperature, 25
Containers discoloring at -40 ° C, bath containers, discoloring at 38-42 ° C, hot food related containers discoloring at 50-80 ° C, kitchen containers In the case of (1), a material that changes color at 50 to 150 ° C. can be used for applications that make use of its appropriate temperature, warning display, variously changing fun, and unexpectedness. In addition, for industrial use, it can be used in a wide range of fields such as measuring the temperature of a radiator-related container of an automobile and measuring the temperature distribution of the container. In a beverage container such as beer, a beer can always be drunk at a suitable drinking temperature by selecting and printing a temperature indicating material suitable for the container. In addition, the temperature indicator portion on the side of the container body corresponding to the beer portion remaining after drinking beer develops color in accordance with the beer temperature (appropriate temperature), but the temperature in the space above the container rises, Since no color is formed, the liquid level of the remaining beer can always be confirmed. For beverages other than beer, the appropriate drinking temperature and the remaining liquid level can be sensed by printing the appropriate drinking temperature on each container.

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Claims (7)

[Claims] 1. A method for printing a plastic container, wherein the temperature indicating ink is printed directly on the plastic container. 2. The method according to claim 1, wherein the printing is performed by screen printing. 3. The method according to claim 2, wherein the screen has a mesh size of 100 to 420 mesh. 4. The method for printing a plastic container according to claim 1, wherein the temperature indicating ink is an ultraviolet curing type. 5. The temperature-indicating ink comprises 0 to 20 parts of a photopolymerization initiator, 0 to 20 parts of a photosensitizer, and 1 to 50 parts of a temperature pigment based on 100 parts of a vehicle. ~
5. The method for printing a plastic container according to any one of 4. 6. A plastic container printed by the method according to claim 1. 7. The plastic container according to claim 6, wherein the plastic container is a plastic container for toiletries.