JPH0812118B2 - Temperature sensitive material - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is directed to printing substrates and background color
The present invention relates to a temperature-sensitive material that develops and changes color in response to temperature changes without any restrictions .

[0002]

2. Description of the Related Art Conventionally, a temperature-sensitive ink prepared by microencapsulating a cholesteric liquid crystal composition and mixing it in an ink vehicle usually has a temperature of dark colors such as black, dark green, navy blue, purple, brown, and red. The spectrum changed according to the change. Therefore, prepare black printing paper,
Two steps were required, such as offset printing the background with black ink. In addition, the form and use of the printed matter tend to be standardized, which sometimes imposes restrictions on application and handling.

[0003]

DISCLOSURE OF THE INVENTION The present invention uses a liquid crystal composition prepared by dispersing a conventional cholesteric liquid crystal in a nematic liquid crystal or a solvent to form a printed matter having a uniform shape and intended use. or is of, or response to the constraints on the application surface and handling
Be Rukoto not, can freely design in without being the color of the limitations of the printing substrate or background, color on a substrate in accordance with the temperature change,
It that aims to create a temperature sensitive material that changes color. Further, by using a temperature sensitive material of the present invention, functions well as authenticity Determination of preventing copying and forgery by copying machines
Etc. and the application means for, Ru can provide high value-added print.

[0004]

Means for Solving the Problems] temperature sensitive material of the present invention, the partial liquid crystal of the cholesteric system liquid or solvent nematic
A liquid crystal composition containing a dispersion, an intermediate dye to reduce sufficiently the effects of the light reflected diffusely transmitted through the liquid crystal composition at the substrate surface, a dye, by combining dye material such as a pigment, a liquid crystal composition the interference color of the object is sufficiently stressed, printing base
It is a temperature- sensitive material that develops and changes color on the base material in response to temperature changes without being restricted by the color of the material or background . As a method of combining a dye material with a liquid crystal composition, firstly, a liquid crystal composition
Ink vehicle that binds microcapsules encapsulating
The dye material method of adding uniformly dispersed, secondly,
The dye material uniformly on the wall film formation material of the microcapsules
There is a method of dispersing and adding.

Examples of the temperature-sensitive cholesteric liquid crystal used in the present invention include cholesteryl chloride, cholesteryl bromide, cholesteryl acetate, cholesteryl 2-ethylhexanoate, cholesteryl n-nonanoate, cholesteryl oleate, and linoleic acid. Cholesteryl, cholesteryl decanonate, cholesteryl laurate, cholesteryl isobutyrate, cholesteryl myristate, oleic cholesteryl carbonate, nonyl cholesteryl carbonate, methyl cholesteryl carbonate, ethyl cholesteryl carbonate, butyl cholesteryl carbonate, isopropyl cholesteryl carbonate, etc. alone or in combination. Can be used.

As a medium for dispersing the cholesteric liquid crystal, a Schiff nematic liquid crystal, a cyanobiphenyl nematic liquid crystal (having 2 to 7 carbon atoms in the alkyl group,
Carbons 3,5 alkoxyl group), another liquid crystal of nematic such terphenyl nematic liquid crystal (the number of carbon atoms in the alkyl group 5), can be used an ordinary ink vehicle or the like.
Further, when the medium is colorless, a medium to which a coloring material such as an intermediate dye or a pigment is added may be used. Further, additives such as antioxidants and preservatives may be added and used.

[0007]

[Action] temperature-sensitive material of the present invention, cholesteric liquid crystals
Liquid crystal composition in which is dispersed in a nematic liquid crystal or solvent
For an ink vehicle that combines encapsulated microcapsules
Dye material was evenly dispersed and added, or
Dye material is uniformly dispersed in the wall film forming substance of Ikuro capsule.
The temperature-sensitive material of the present invention, because it is the temperature-sensitive material added by
The as a printing ink when used, transmitted through the liquid crystal composition
In a situation where the effect of light diffusely reflected on the substrate surface is reduced
Dyes, dyes, pigments and other coloring materials are uniform on the substrate
Fixes in such a dispersed state that the scattered light from the substrate surface is sufficient
Since it absorbs , the interference color of the liquid crystal composition changes depending on the temperature change.
Fully emphasized, not subject to color restrictions on the printed substrate or background
The printed matter having good spectral changes is obtained, et al.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 (a) and 1 (b) are conventionalsame(C) is a book
The composition and working principle (optical effect) of the temperature-sensitive material of the invention are shown.
Figure 1 (a), (b), (C)Are each black
Base material (2)OrA certain temperature on the white base material (3)Under
Refractive index (N)Microencapsulated liquid crystal composition
(1), Combined with the ink vehicleFilm thickness (h)mark
PrintingThin film layerAs opposed toIncident light (A) enters at incident angle (i)
Reflected light when shining (B),The thin film layer is transmitted at an angle of refraction (θ).
Absorbed light (C) absorbed by the black substrate (2)as well asscattering
The state of light (D) is shown.

Since the incident light (A) is almost absorbed by the black base material (2) of FIG. 1 (a), it is considered that there is no influence of the scattered light (D), but it is scattered on the white base material (3). The interference of the interference light is canceled by the strong influence of the light (D), and it is difficult to capture the interference color.
In FIG. 1C, the white base material (3) for the incident light (A )
Since the oil-soluble dye (4) uniformly dispersed in the ink vehicle sufficiently absorbs the reflected light from the scattered light (D)
Is suppressed, and the interference color due to the liquid crystal composition (1) is sufficiently emphasized.

The relationship between (θ) and (N) is expressed by N = sini / sin θ. Further, the wavelength when the light reflected on the upper surface and the light reflected on the lower surface of the liquid crystal composition (1) are maximally mutually strengthened is represented by λ _max , and the wavelength when they are weakened each other is represented by λ _min , the following equation is obtained. ^{_{λ max = 4h (N 2 -sin}} 2 i) 0.5 / (2n-1) λ min = 2h (N 2 -sin 2 i) 0.5 / n where, n is an integer.

The addition amount of the purple dye and the yellow dye as the oil-soluble dye (4) added to the ink vehicle is 2
For a liquid crystal composition that develops a green color (black background) at 6.5 ° C., the ambient temperature is 25.4 ° C., 26.7 ° C., and 3
At 0.5 ° C., the regions are as shown in FIGS. 2 (a), 2 (b) and 2 (c). In the figure, the region (Y) is from yellow to brown (λ _max is about 570 nm or more, i =
0) shows the addition amount of a yellowish dye, and similarly, in the region (G) , the color of the liquid crystal composition to which the above dye is added ranges from yellow green to blue green (λ _max is 480 nm to 570 nm).
, I = 0), and the region (V) ranges from blue to purple (λ _max is about 400 nm to 480 nm, i
= 0) purple type. Based on FIG. 2, a desired addition amount can be appropriately selected and used.

The above liquid crystal composition (1) comprises olein cholesteryl carbonate 80 parts, cholesteryl bromide 5 parts, and p-ethoxybenzylidene-p'-butylaniline (EBBA).
(Abbreviated) 15 parts by weight of the liquid crystal composition . This liquid
Microcapsules Encapsulating Crystalline Composition (1)
As the oil-soluble dye (4) to be added to the ink vehicle , any oil-soluble dye can be used, and examples thereof include disperse dyes, architectural dyes, a part of metal-containing acid dyes, sulfur dyes and disperse dyes. In addition to photo-whitening agents and oil-soluble dyes such as naphthol dyes, insoluble pigments (pigment pigments), lakes (lake pigments), natural dye pigments, nitroso pigments, nitro pigments, azo pigments, phthalocyanines Pigments,
An organic pigment such as a quinacridone pigment, a dioxazine pigment, or an isoindolinone pigment, which is used alone or in combination, is used.

[0013] Figure 3 is a printed material prepared by using a temperature indicating inks consisting of temperature sensitive material of the present invention will be described the working principle. The ink is one that develops heat and changes color at room temperature, and the shape of the segment was printed so as to indicate the room temperature from 25 ° C to 29 ° C. When the room temperature is lower than 25 ° C., the color of each segment is brown. Room temperature is 2
When the temperature reaches 5 ° C., only the temperature indicating ink (5) that develops color (green) at 25 ° C. develops color and displays 25 ° C. Then, when the room temperature reaches 26 ° C., in addition to the temperature-sensitive ink (5) which develops color (green) at 25 ° C., the temperature-sensitive ink (6) which develops color (green) at 26 ° C. develops and discolors to 26 ° C.
Is displayed. Furthermore, when the room temperature is 27 ° C., a temperature indicating ink (5) that develops color (green) at 25 ° C. and 26 ° C.,
In addition to (6), the temperature-sensitive ink (7) that develops color (green) at 27 ° C. develops color and displays 26-27 ° C. Similarly, at room temperature of 28 ° C., the temperature indicating ink (8) that develops color (green) at 28 ° C. develops color and displays 28-27 ° C. Finally, at room temperature of 29 ° C., the temperature indicating ink (9) that develops color (green) at 29 ° C. develops color to display 28-29 ° C. Also,
When the room temperature exceeds 29 ° C., all of the thermosensitive inks show a blue to purple color to notify that the measurement range has been exceeded. In FIG. 3, the temperature indicating inks (5), (6), (7), which develop colors at the respective temperatures,
The composition of the liquid crystal composition (1) contained in (8) and (9) is 79.6 to 89.6 of oleic cholesteryl carbonate.
0.8 parts, cholesteryl bromide 4.2-5.5 parts and EB
It will be decided at BA15.

Three-component liquid crystal set of olein cholesteryl carbonate, cholesteryl bromide and EBBA (constant at 15%)
FIG. 4 shows the relationship between the mixing ratio C [%] of oleic cholesteryl carbonate and the absolute temperature T [K] when a green color is formed on the black background in the product (1). As shown in the figure, in a specific range of the mixing ratio of oleic cholesteryl carbonate, 72% to 85%, the relationship between the mixing ratio C [%] of oleic cholesteryl carbonate and the color development temperature T [K] is considered to be approximately linear. Therefore, apply it to an appropriate approximation formula,
By performing the simulation, it is possible to predict the color temperature from the mixing ratio of carbonate oleic cholesteryl, calculates the mixing ratio from the coloring temperature.

Figure5(A), (b) are conventional,same(C) is
The present inventionofPrinciple and working principle of microcapsule (optical
It is a schematic diagram showing the effect. The microcapsules (1
0) Is a core substance and a wall film forming substance (11) Consists of a core
Temperature sensitiveLiquid crystal composition(1) is used to form a wall film
quality(11) Form a hydrophilic thin film. Figure5
(A) and (b) are black base materials (2), respectively.OrWhite base material
(3) Microcapsule (10)ToIncident light (A)
Reflected light (B), absorbed light (C) and scattered light when incident
The state of (D) is shown. Figure5(A) Black base material
In (2), most of the incident light (A) is absorbed, so scattered light
(D) is considered to have no effect,5(B) white
On the base material (3), the influence of scattered light (D) is strong and interference light strikes.
It is erased and it is difficult to capture the interference color. Figure5In (c),My
Dispersed uniformly in the wall film forming substance of black capsuleWater soluble
dye(12)ByIncident light (A) and white base material
Light reflected from (3)Is enoughabsorptionIsOf scattered light (D)
InfluenceButHold downBeSoLiquid crystal compositionInterference color due to (1)
ButEnoughTo be emphasized.

The microcapsules of the present invention are usually prepared by a coacervation method in which 0.05% to 5% of a cationic black dye is added to an aqueous solution in which a wall film forming substance composed of gelatin and gum arabic is dissolved. It is microencapsulated. The microcapsules were combined with an ink vehicle to form an ink, which was screen-printed on white wood free paper. The printed matter shows a yellowish brown color at room temperature (less than 28.4 ° C), but when a copy is attempted with a color copier, the glass turns green at a surface temperature of 28.4 ° C or higher and purple at 30.5 ° C or higher. Therefore, this printed matter cannot be reproduced by a copying machine. As the wall film forming substance used for microencapsulation, for example, gelatin, shellac, gum arabic, rosin, rosin ester, ethyl cellulose, carboxymethyl cellulose, paraffin, tristearin, polyvinyl alcohol, polyethylene, polypropylene, acrylic resin, Vinyl resin, polyisobutene, polybutadiene, epoxy resin, phenol resin,
Polyurethane, polyester, polyamide, silicone, polystyrene, melamine resin and the like can be used alone or in combination. Further, if necessary, a pigment material may be added to the wall film forming substance and used in the capsule manufacturing process.

As the microencapsulation method, for example,
Perform by the usual methods such as coacervation method, interfacial polymerization method, in-situ polymerization method, submerged curing coating method, phase separation method from organic solvent, submerged drying method, air suspension coating method, spray dry method, etc. You can The prepared capsule slurry is decanted or treated with a stabilizer, filtered or pulverized, and dispersed in an appropriate binder to obtain an ink. For example, screen printing or offset printing is performed on the printing substrate. Alternatively, it may be used in combination with an intaglio, letterpress, offset, gravure, flexo, screen-printed material, and the like. Alternatively, it can be used not only as a printing ink but also as a paint or coating agent.

Examples of the printing substrate include plain paper such as high-quality paper and coated paper, film-like materials such as glassine paper, cellophane paper, and freon film, polyethylene, polyprene, vinyl chloride, polyurethane and Teflon sheet. Sheet-like material, fluororubber, isoprene rubber, butyl rubber, silicone rubber, natural rubber and other latex-like material, polyester, polyamide, polyamideimide,
Polyethylene, polypropylene, cellulose acetate, Polycarbonate, polyvinyl chloride, a resin plate-like object such as fluorine resin, it is possible to also print to those of the shaped metal foil such as aluminum foil, non-coated paper, medium-quality paper It is desirable to use plain paper with low gloss and reflection, such as recycled paper and Japanese paper, which has excellent ink transfer properties.

As the water-soluble dye ( 12 ) to be added to the wall film forming substance ( 11 ) of the microcapsule ( 10 ) of the present invention , any hydrophilic one can be used, for example,
Water-soluble dyes such as direct dyes, acid dyes, metal-containing acid dyes, basic dyes, cationic dyes, mordant dyes, acid mordant dyes, azoic dyes, soluble architectural dyes, soluble sulfur dyes, reactive dyes, natural minerals, man-made An inorganic color pigment such as an inorganic compound or the like, which is used alone or in combination, is used.

Preferred ink vehicles for binding the microcapsules ( 10 ) of the present invention include oils and fats such as linseed oil, olive oil, castor oil, sunflower oil, whale wax, beeswax, lanolin, carnauba wax, candee. Natural waxes such as rear wax and montan wax, paraffin wax, microcrystalline wax, oxidation wax, ester wax, synthetic waxes such as low molecular weight polyethylene, lauric acid,
Higher fatty acids such as myristic acid, palmitic acid, stearic acid, flomenic acid and hebenic acid, higher alcohols such as stearyl alcohol and hebenyl alcohol, soaps such as petrolatum and glycerin, hydrocarbons such as glucose, ethylene glucose and amylose , Esters such as fatty acid ester, amides such as stearamide, oleinamide, polyamide resin, polyester resin, epoxy resin, polyurethane resin, acrylic resin, vinyl chloride resin, cellulose resin, polyvinyl -Based resins, petroleum-based resins, ethylene-vinyl acetate copolymer resins, phenol-based resins, styrene-based resins, rosin-modified resins, resins such as terbine resins, natural rubber,
An ink vehicle composed of elastomers such as styrene-butadiene rubber, isoprene rubber, and chloroprene rubber, tackifiers such as hydrogenated petroleum resin, silicone, liquid paraffin, and fluororesin, which may be used alone or in combination, may be used. Further, if necessary, an ink vehicle composition obtained by adding a surfactant, a filler, an antioxidant, a desiccant, etc. to the ink vehicle may be used. Further, when the ink vehicle is colorless and transparent, it can be used by adding an appropriate intermediate dye, dye, pigment or the like if necessary.

[0021]

The temperature-sensitive material of the present invention is a cholesteric material.
Liquid crystal of liquid crystal of nematic liquid crystal or solvent
Inkibihi coupling the microcapsules encapsulating Narubutsu
The pigment material is evenly dispersed and added to the
Distributes the pigment material to the wall film forming substance of the microcapsules.
It is a temperature-sensitive material that is dispersed and added to
By using the material as a printing ink, the printing group
Depending on the temperature change, without being restricted by the color of the material or background
Printed matter is obtained showing a spectral change Te, Ru obtained printed matter impart added value. In addition , standard body temperature and mechanical heat generated by office equipment control the color of the printed substrate and background.
Without being limited, color according to temperature changes, since the discoloration,
In particular, it is possible to prevent copying or forgery by a color copier or a scanner.

[0022]

[Brief description of drawings]

FIG. 1 is a diagram illustrating a configuration and an operating principle of a conventional temperature-sensitive material and a temperature-sensitive material of the present invention.

FIG. 2 is a diagram showing a region of interference color at each temperature when a purple dye and a yellow dye are added to a liquid crystal composition .

FIG. 3 is a diagram illustrating a configuration and an operating principle of a printed material using the temperature-sensitive material of the present invention.

FIG. 4 is a mixing ratio C [%] of oleic cholesteryl carbonate in a liquid crystal composition and a color development temperature (green) T on a black background.
The figure which showed the relationship with [K].

FIG. 5 is a schematic view of conventional and present microcapsules .

[0024]

[Explanation of symbols]

1 The liquid crystal composition 2 Kokushokumotozai 3 white substrate 4 oil-soluble dyes 5-9 thermochromic ink 10 microcapsule 11 wall membrane forming material 12 a water-soluble dye

Claims (2)

[Claims] 1. A liquid crystal composition obtained by dispersing a cholesteric liquid crystal in a nematic liquid crystal or a solvent is used as a microcapsule.
Ink to bind the microcapsules
Uniformly dispersed in Le intermediate dyes, dyes, dye material such as a pigment
Are limited by the color of the printing substrate and the background.
A temperature-sensitive material that develops and changes color in response to temperature changes. 2. The liquid crystal composition is microencapsulated.
At that time, a pigment material such as an intermediate dye, a dye or a pigment is uniformly dispersed and added to the wall film forming substance of the microcapsule ,
Do not combine the microcapsules with an ink vehicle.
The temperature-sensitive material according to claim 1, wherein