JPS6223294B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates generally to color displays, and specifically to the shutter of color displays, which do not themselves qualify as displays. The color display of the present invention is activated by differential color-darkening information in the form of an image or contrasting tint appearing beneath the surface shutter layer of the display.

The present invention particularly relates to magnetically operated substantially two-dimensional shutters that produce reversible and variable degrees of transparency or translucency. More particularly, the present invention relates to an improved shutter display that increases visual differentiation by providing a contrasting coloration when comparing the shutter layer to the underlying substrate. The present invention relates to a shutter display having such selective tints of color.

U.S. Patent No. issued February 14, 1961
No. 2971916 disperses magnetic particles in an oily liquid,
It is disclosed that the magnetic particles are contained in microcapsules, the capsules are coated on the magnetized portion of a magnetic sheet, and the capsules are finally pressure-ruptured against the receptor sheet, resulting in the magnetic particles transferring to the receptor sheet. .

U.S. Pat. No. 3,221,315, issued November 30, 1965, discloses iron flakes as a desirable magnetic material having the shutter effect and being dispersed in the oil contained in the microcapsules used in the display. details a magnetic-responsive display using The display of that patent exhibits a difference in appearance between a selected portion and a non-selected portion by means of magnetic particles that are oriented to transmit more or less light in response to an effective magnetic force applied to the selected portion. . However, the patent does not mention the use of color contrasting effects or colorants with respect to the various elements of the capsule, including the display base material and binder film.

U.S. Patent No. 3320523 issued May 16, 1967
No. 1, No. 1, No. 1, No. 1, No. 1, No. 1, No. 1, No. 1, 2006, 2006, 2003, discloses a magnetic field detector comprising a dry emulsion coating of a magnetic material in an aqueous medium. The magnetic particles are aligned to varying degrees at different magnetic field strengths, and the alignment is revealed by changes in the reflection of the projected light. However, it does not discuss the contrast effect of hues or the suitability of coloring materials.

U.S. Pat. No. 3,683,382, issued August 8, 1972, also discloses a magnetic-responsive display. However, this display used a coating of mobile magnetic particles in the base layer, and the coating was of such a thickness that all projected light on the coating would be completely absorbed if not reflected from the magnetic particles. Therefore, light does not completely pass through the coating in any mode of particle arrangement. The shutter effect is then completely eliminated, so no mention is made of the combined effect of the various shades provided in the substrate layer or in the coating.

U.S. Pat. No. 3,673,597, issued June 27, 1972, discloses a magnetic-responsive display that utilizes the coating of microcapsules containing light-reflective pigments and magnetic particles in a molten dispersion medium. Contains sexual flakes. Once melted, the fusible medium permanently positions the flakes and pigments within the microcapsules. Projected light on the display appears reflected from the flakes or from the pigment. The contents of the microcapsules do not transmit the projected light and either reflect or absorb it.

It operates by reflecting projected light and uses a coating of mobile magnetic flake particles as a reflector.
A magneto-responsive display is "reflective" when the mobile magnetic flake particles are uniformly arranged so as to significantly reflect the projected light. When the magnetic particles are arranged in such a way that the projected light is transmitted and not reflected, the particles are generally "absorbing," in which case the coating is thick enough to penetrate deep into the coating without escaping anywhere within the coating. absorbed by internal reflection between particles,
be captured. "Transmissive" is indicated when the coating is not so thick that non-reflective projected light is absorbed by subsurface particles. The "transmission type" is indicated when the magnetic particles are aligned such that the projected light is transmitted and the concentration of particles below the surface is low enough for the light beam to emerge from the coating on the opposite side of the projection.

Prior art magnetic-responsive displays have generally been unsatisfactory for at least two reasons. First, there were displays using high magnetic particle concentrations and thick coatings such that all light rays that entered the coating and were not reflected from it were absorbed within the coating, producing a black display image. These thick "ray-trapping" coatings do not allow adequate light transmission to take advantage of the contrast provided by the substrate layer. The coating requires a large amount of material and is therefore generally expensive. Additionally, relatively strong signal-like magnetic fields are required to properly align large amounts of magnetic material and provide optimal imaging. Second, the visual contrast between reflective and absorptive or transmissive particles is generally weak due to the absence of colorant components and the presence of small amounts of magnetic material, and there is no difference in hue exhibited between each type. It was a shutter type display. In addition, in order to maximize the contrast of a display that does not have the advantage of differences in color between each type,
It was necessary to make the arrangement of the magnetic material almost perfect.

The present invention significantly improves magnetically responsive displays by providing a shutter display with enhanced contrast between reflective and transmissive types through the use of colorants in the paint containing magnetic particles. . Another improvement is the provision of colorants in the base material, which can also be used in the film-forming matrix binder present in the paint or overcoat. The colorant may be dispersed or dissolved; if dissolved, it is considered a molecular dispersion.

One object of the present invention is to provide an improved magnetically responsive obscurant shutter display with increased visual contrast using a colorant as an element in contact with a magnetically responsive material. be. In addition, it is an object of the present invention to provide an improved shutter having microcapsules containing a colorant as a visual contrast enhancer and an oily dispersion of magnetic particles as a reflective element.

Another object of the invention is to include in the film,
It is an object of the present invention to provide an improved shutter having a large number of microcapsules arranged in an array, where the shutter exhibits a significant contrast in visual appearance between transmission and reflection due to the arrangement of magnetic particles. Another object of the invention is to provide a display having improved shutter with high transmission properties in a film having microcapsules containing colorants either in the walls of the microcapsules or in the microcapsules. The microcapsules are in such a large quantity in the film that adjacent microcapsules are in fact in contact with each other, and the shutter is in contact with an underlying substrate having a hue that contrasts with the hue of the colorant in the microcapsules. at least partially).

In addition, it is a further object of the present invention to have a clear contrast in color in terms of the difference between reflective and transmissive types, and to make the capsules within a critical mass suitable for the amount of magnetic material and the size of the capsule. The aim is to provide a shutter using capsule film.

The article of the present invention is a reversible, selective, variable, displayable, substantially two-dimensional shutter. The article is magnetically operable and consists of a binder enriched with microcapsules containing a dispersion of colorant and magnetic material in a liquid medium. The magnetic material is generally in the form of flakes, mobile and free to move in the liquid medium in the microcapsules. A magnetic field near the capsule's film aligns the magnetic flakes. The plane in which particle alignment occurs reflects the projected light when the flakes are parallel to the plane of the film, and transmits the projected light when the flakes are perpendicular to the plane of the film.

A key feature of the article of the invention is the use of colorants and different shades to improve the visual contrast between the transmissive and reflective versions of the shutter display element. In this application, the term "coloring material" means a colored substance, and the visual impression of the substance is defined as a "hue." The use of colorants and their different shades is achieved by providing the colorant in a dispersion of encapsulated magnetic particles, and when the alignment of the magnetic particles is parallel to the substrate display surface, the shade of the encapsulated colorant changes. It relates to the display surface of the substrate exhibiting a tint as shown and when the alignment of the magnetic particles is perpendicular to the substrate surface, the tint of the substrate surface is shown. The proper concentration and density of magnetic particles is critical to the success of the article.

The microcapsules are generally substantially spherical;
They range in size from about 5 to about 1000 microns (or slightly larger) in average diameter. The shape of the spherical capsule is important to ensure that the magnetic particles move within the capsule. The size of the capsule is also related to the mobility of the magnetic particles. The longest part of the magnetic particle should not be so large relative to the size of the capsule that the mobility of the particle within the capsule is impaired. Magnetic particles that are too large restrict their mobility, and particles that are too small tend to lose their flake-like properties.

The capsule wall material is generally a combination of materials or a film-forming polymeric material that does not affect or dissolve the materials within the capsule, and is substantially permeable to allow operation of the present invention. Examples of suitable materials include those commonly used to form capsules for other purposes: natural materials such as gelatin and gum arabic; poly(acrylic acid), poly(methacrylic acid), poly(vinyl synthetic polymeric substances such as alcohols) and copolymers such as poly(methyl vinyl ether-co-maleic anhydride) and poly(styrene-co-maleic anhydride) (hydrolysed and non-hydrolysed). The encapsulating liquid is generally an oily material that is substantially insoluble in water, since suitable capsule wall materials are usually water soluble. However, organic solvent soluble polymers can also be used in the capsules of the present invention, provided there are no adverse effects between the capsule wall and the capsule contents.

As mentioned above, the liquid contained in the capsule is
Preferably it is oily and insoluble in water. Exemplary materials include mineral and vegetable oils, including volatile liquids such as benzene, toluene and cyclohexane and non-volatile liquids such as chlorinated biphenyl and peanut oil. Depending on the choice of capsule wall material,
Water-soluble or aqueous capsule contents may also be used. It should be understood that combinations of liquids may also be used. The containing liquid acts as a dispersion medium for the colorant and mobile magnetic particles. The success of the present invention is dependent on the mobility of the magnetic particles in a magnetic field, and the containing dispersion medium is within the range of about 1 to about 1000 centipoise or perhaps slightly higher, preferably within the range of about 5 to 30 centipoise, compared to It was found that the viscosity should be unaffected by the target temperature. A dispersion medium that is too viscous will not respond or will respond slowly to a magnetic field, while a dispersion medium that is too low in viscosity will provide unstable shatter.

The magnetic particles should be flakes, disks, plates or leaves in nature. The particles have an average length of about 0.5 microns, with an average longest length ranging from about 1 to about 40 microns. The "flakeness" of the particles is described in terms of a quantity known as the "aspect ratio." The aspect ratio is the ratio of the surface area of one average flake side to the average flake cross-sectional area, and the aspect ratio of suitable magnetic particles is approximately 5.
It should be between 100 and preferably between about 5 and 40. It should be stated that effective shutter operation requires that the projected light be completely transmitted through the shutter element without being absorbed. It appears that the larger the aspect ratio of the magnetic particles, the more the projected light passes through the shutter film as they are of a transmissive type. The magnetic particles are made of iron, especially carbonyl iron,
It can be nickel, stainless steel and other alloys and other paramagnetic materials. The magnetic particles may be non-magnetic flakes coated with or otherwise combined with a magnetic material to provide magnetic responsiveness.

Although the colorant is preferably molecularly dispersed (dissolved) in the dispersion medium, insoluble colorants are also useful if finely dispersed. The purpose of the colorant is to increase the visual contrast between the projected light reflected from the capsule coating colorant and the projected light reflected from a medium of a different shade than the colorant. A finely dispersed colorant scatters projected light more than a molecularly dispersed colorant. The average particle size of the undissolved colorant should not exceed about 1 micron, and the final undissolved colorant particle size is preferably about 0.1 to 0.5 micron. Examples of suitable colorants are manufactured by Hilton-Davis Chemical Company, Cincinnati, Ohio under the trade names listed below.
Oil Red, a dye sold by Company, Cincinnati, Ohio
Hidaco) 20-6051; Oil Yellow Hidaco (Oil
Western Solvent and Chemical Company, Romulus, Michigan (Western Solvent and Chemical Company, Romulus, Michigan)
and Chemicals Company, Romulus,
Dyes sold by Michigan), Oil Yellow 3G; Oil Yellow AR15138; Oil Yellow 151137; Oil Yellow IOS15679;
& Co. Wilmington, Delaware (EIdupont de Nemours & Co.,
Oil Yellow NB (Solvent Yellow) is a dye sold by Wilmington, Delaware.
56, P-diethylaminoazobenzene - Color Index 11021); Oil Blue A, and a pigment sold by Hilton-Davis Chemical Company under the trade names:
Permanent red 2B, 5-17-F-102; Phthalocyanine green, blue shade, 5-65-
There is F-41.

The capsules can be manufactured by any convenient method already disclosed in the prior art. The capsule manufacturing method for the present invention is not part of the present invention.
A preferred method of manufacturing the capsules is as follows: September 12, 1967
U.S. Patent No. 1, each issued on April 1, 1969.
No. 3341466 and No. 3436355. Depending on the particular concentration to be maintained of magnetic particles in the shutter film, the following concentrations and volumes are preferably used in combination with others; the capsules contain about 50% of the liquid capsule core material dispersion From about 95
Preferably it should contain from 75 to 85% by weight, and the liquid capsule core material should preferably contain from about 5 to about 60% by weight.
It should contain from 15 to 30% by weight of magnetic particles and in addition from about 1 to about 20, preferably from 2 to 10%, colorant.

In order to create a cohesive and effective shutter,
The capsules are held within a film formed of a polymeric binder material. The binder material does not interfere with the transmission of light between capsules and also acts as an adhesive between the capsules and the substrate. The binder material can be dissolved in any solvent used to disperse the capsules. The only requirement for the solvent is that it not have an adverse effect on the capsule wall material and at the same time dissolve the binder material. Of course,
The binder material should dry as a substantially transparent film. If an aqueous solvent is used to disperse the capsules, binder materials such as starch, guar gum, gum arabic, polyvinyl alcohol, gelatin, carboxymethyl cellulose, water-soluble acrylate polymers, etc. are suitable; Polymer and copolymer latex coating systems, such as, are also suitable. When using an organic solvent, suitable binder materials include polystyrene and polystyrene copolymers, polyvinyl acetate and its copolymers, organic solvent soluble acrylate polymers and copolymers, nitrocellulose, ethylcellulose, polybutadiene, polyurethane, etc. There is. In short, any substantially transparent polymeric material that meets the above requirements can be used as a binder.

A dry film consisting of a binder material and a capsule is the shutter of the present invention. The film is constructed such that when the magnetic particles are aligned parallel to the film, they substantially block the transmission of the projected light, and when the magnetic particles are aligned perpendicular to the film, the projected light is substantially transmitted. It must be done. To produce a film in this manner, the capsules must be present in the shutter in such an amount that adjacent capsules are in virtual contact with each other, and the concentration of magnetic flake particles in the film must be such that the particles The total flat surface area is
Approximately 1 of the shutter area covered by the film
10 times, preferably 2.0 to 4.75 times. "Particle planar area" is the surface area of only one side of each particle. Although the reason is not completely understood, the "Coverage ratio" of the total flat side grain area to the shutter film area is affected by irregularities in grain shape, imperfections in film formation, and reflection type. is clearly larger than 1 due to the incomplete alignment of the particles and the possibility of incomplete dispersion of the flakes in some capsules. The above idea is that when the shutter is a reflective type, the individual magnetic particles need to overlap to some extent, but when the shutter is a transmissive type, care must be taken not to make the concentration of magnetic particles so high that the projected light is absorbed. There must be.

Measurement of the planar area of magnetic particles involves floating a known amount of the magnetic flake particles on the surface of water under carefully controlled conditions and then measuring the covered surface to calculate the surface shielded per unit amount of particle. This can be done by measuring. A detailed description of methods for measuring the area of particle planes is given in “Aluminum Paints and Powders” by J.D. Edwards and R.I. Uley, Reinhold Publishing Co., New York (1955).
Found on pages 18-22.

The film can be used with or without adhesion to a contrastingly colored substrate display surface. In any case, the shutter film is used in combination with an underlying surface that is at least partially of a somewhat different shade. The shutter film can be formed by coating a substrate surface (regular or irregular) with a dispersion of the capsules in a liquid solvent of a binder material. The painted dispersion is then dried, creating a thin film of capsules encapsulated in a binder material, conforming and adhering to the substrate surface. An example of a regular substrate surface is a polyethylene terephthalate plastic film. An example of an irregular substrate surface is paper or other fibrous material (woven or non-woven). Gross irregularities exhibited by the surface of an embossed, engraved, molded or otherwise shaped article are also included within the meaning of regular or irregular surface.

The shutter film is placed in contact with but not adherent to the underlying surface and can be used in combination with an underlying surface of different shades. This is undesirable as a method of using the shutter film because satisfactory operation requires virtually intimate contact between the film and the underlying surface.

As a method of applying the composition, any method of application which allows sufficient control of the thickness of the coating and therefore of the concentration of magnetic particles in the shutter film is suitable. On small surfaces, bar-
Painting methods such as spray, air knife, reverse roll, extrusion, and curtain methods can be used for large surfaces.

The visual response of the coatings of the present invention as a function of the coating weight used to make the magnetically responsive display will now be described with reference to various figures. The coating weight is referred to as an "active" coating weight, meaning that it contains no binder material. “Active” paint weight is 25
A series of 500 x 38 inch (3300 square feet) painted dry capsules and poundage of capsule contents. Graphs were made from the coatings and displays produced in Examples 1 and 2 of the invention, generally relating to the effect of the shutter and the base colorants of the invention.
In these examples, the colorant-containing capsules are yellow;
The color of the underlying substrate is red.

Figure 1 shows the active coating materials and Hunter Color light reflection values on the “a” chromaticity axis (red→green) for reflective and transmissive display coatings.
light refectance values). [Hunter chromaticity scales, developed by Richard S. Hunter, have an "L" axis that corresponds to luminosity, an "a" axis that measures hues from red to green, and an "a" axis that measures hues from yellow to blue. b”
The numbers on the axis represent what was established by equally matching human visual senses. RS Hunter, “Photoelectric tristimulus colorimetry using a three-color filter,” National View of Standard Circular No.
429, U.S. Government Printing Office 1942] Figure 2 shows the difference in the "a" axis of Hunter color units between reflective and transmissive types for various active coating weights.

FIG. 3 shows the color purity of the reflected light from the display in reflection and transmission for various active coating weights.

FIG. 4 shows the dominant wavelength of reflected light from the display in reflective and transmissive modes for various active coating weights.

To explain the diagram in detail, the vertical axis of FIG. 1 generally shows hue extending from red human vision at one end to green human vision at the other end. The test shutter display considered in this invention has a red opaque base layer, and the effectiveness of the shutter is determined by the extent to which the red base is obscured by the operation of the shutter for various paint weights. A decrease in the value on the vertical axis means a decrease in redness. First, the line labeled "reflective" represents the test shutter display in which the magnetic flakes are aligned parallel to the substrate surface, thus shielding the red substrate as much as possible. It can be seen that at points where the active coating weight is very low, the red color is not well hidden because it is incompletely covered by the magnetic flakes. The reflective curve goes from a red scale to a green scale at about 15 pounds per series of active coating. The line labeled "transmission" then represents the test shutter display when the magnetic flakes are aligned perpendicular to the substrate surface, thus maximizing the visibility of the red substrate.
At very low active paint weights, the magnetic particles do little to obscure the red color, but as paint weight increases, the magnetic flakes tend to block the appearance of the red substrate. The transmission curve goes from a red scale to a green scale at 35-40 pounds per series of active coating.

As described above, the line in FIG. 2 represents the difference (Δ) in the "a" axis unit between the reflective and transmissive hunter colors described in FIG. The difference shows the difference in colorants between reflective and transmissive types at various paint weights. It can be seen that the curve peaks at about 15 pounds per series. On either side of the peak, the color difference is reduced. On the side where the coating weight is low, when using the reflective type, the color difference of the substrate is not sufficiently hidden, so the difference in color decreases, and on the side where the coating weight is high, when using the transmissive type, the alignment of the magnetic particles is poor. and edge effects mask some of the hue of the substrate, thereby reducing color differences.

By reading Figures 3 and 4 together, we can determine the dominant wavelength of reflected light from the test shutter display in reflective and transmissive types, and the percentage of reflected light (within 1 or 2 nanometers) at that dominant wavelength. can. It should be understood that the shade of the unpainted substrate exhibits a dominant wavelength of 613 nanometers and a color purity of 71% at that wavelength. The reflective version exhibits a color purity of 45-50% over the entire paint weight range, with a dominant reflection wavelength of about 574-577 nanometers (yellow) above about 15 pounds per series of active paint weights. In the transmission type, color purity decreases as the coating weight increases,
Its color purity decreases almost linearly at dominant wavelengths from above 600 nanometers (orange) to below 580 nanometers.

The figures described above are useful in generally describing shutter displays. It is contemplated that the diagram could be used to depict paint weights that are highly suitable for effective shutter display. however,
Since shutter displays are made for human visual response, the effectiveness of the display is best judged by visual response. Effective shutter spray requires a surprisingly narrow range of active coating weights, which in turn requires a narrow range of magnetic flake concentrations and, more specifically, a narrow range of satisfactory coating weights. The desired shielding ratio is obtained.

Looking at FIG. 2, it can be seen that the difference between the coloring material of the capsule and the hue of the substrate is about 60% of the maximum.
To a lesser extent, the shutter display was found to be visually effective. The range of satisfactory active coating weights for the component systems of the figures (Examples 1 and 2) is therefore from about 10 to about 30 pounds per series. The active coating weight range is about
Represents a range of magnetic flake shielding ratios from 2.0 to about 4.75.

Capsules for use in the present invention can be made by any of several known encapsulation methods. The presently preferred method is US Pat.
It is similar to that disclosed in No. 3341466.
The method produces relatively uniformly sized capsules with a small amount of capsule core and generally having an average diameter ranging from less than 10 microns to more than 1000 microns and possibly as large as 15000 microns.

As mentioned above, preferred encapsulation methods are disclosed in the prior art, but for clarity, suitable encapsulation methods are repeated below.

The wall-forming polymeric materials are pork skin gelatin and gum arabic, which have an isoelectric point of about PH 8-9.

2-Put the following into a beaker.

Water 800 ml Gelatin aqueous solution containing 11% by weight of pork skin gelatin with an isoelectric point of PH8-9
180 ml Aqueous solution of gum arabic containing 11% by weight of gum arabic 180 ml Next, the system was stirred and the temperature was raised to approximately 40-55°C, and the pH of the system was adjusted to approximately 40-55°C using a 20% by weight aqueous sodium hydroxide solution. Adjust to 9. Next, 160 g of magnetic particle dispersion in oil is added to the system as a capsule inner layer. The system is agitated until the magnetic particle-containing oil is dispersed to the desired size, such as on the order of about 5-80 microns. Once this point is reached, the pH of the system is slowly lowered to about 4.2-4.4 while stirring to induce coacervation, which only takes a few minutes. While stirring, the temperature of the system is lowered to room temperature (25±5° C.) over a period of about 30 minutes, and a composite polymer liquid material is precipitated around the oil droplets that form the internal phase containing the magnetic particle suspension. With continued stirring, the system is cooled to about 10° C., causing the liquid wall precipitate of the polymer composite material to gel. These gelled capsules are complete apart from the next step of crosslinking and curing in the residual aqueous vehicle. Curing is 25
This can be achieved by adding 10 ml of an aqueous solution of glutaraldehyde at % by weight and stirring for 1 to 20 hours, during which time the temperature of the capsule slurry is adjusted to room temperature.

The capsules are generally used and painted, preferably in an aqueous medium. When using capsules made by the method described above, it is convenient to paint the capsules directly from the aqueous capsule manufacturing vehicle.
However, if otherwise desired or necessary, additional materials can be used with the production vehicle or the aqueous production vehicle can be replaced with other aqueous component systems and different or additional binder materials can be used. It is also possible.

Capsules with dry capsule walls can be formulated into coating compositions having aqueous or organic vehicle component systems. It is, of course, required of any coating composition that the viscosity and solids content be appropriate for the desired application process.

In the examples below, "percent" means percent by weight.

Example 1 In this example, a coating composition was prepared using the previously disclosed encapsulation method. The oil contained in the capsule may be, for example, dioctyl phthalate, chlorinated biphenyl or a high boiling petroleum solvent. Small amounts of surfactants can be used to facilitate dispersion of the magnetic particles. The high-boiling petroleum solvent is, for example, a solvent consisting of 48.6% paraffin and 51.4% naphthene and having a boiling point range of 390 to 496〓 (from Magnaflux Corporation under the trade name Magnaflux Oil). Commercially available] is fine.
The surfactant may be sorbitan triolate.
Combinations of solvents can also be used. The magnetic particles are flakes of nickel metal with an aspect ratio of about 16 and a longest dimension of about 40 microns. The magnetic flakes are MD-
It may be commercially available from Alcan Aluminum Corporation (Elisa Base, New Jersey) under the trade name 756. The flakes have been determined to have a specific shielded area of 5600 cm ² per gram of flake by Alkane Aluminum Corporation using the method described above. The specific coverage area amounts to approximately 1.2 pounds of theoretical or complete flake coverage per series. The magnetic particles are about 19% of the capsule component system (about 33% for oil). The coloring material is the above-mentioned Oil Yellow 3G, which accounts for 1-5% of the capsule component system. The capsules are about 5 to 80 microns in average diameter and contain about 80% magnetic particle oil dispersion.

The vehicle for the coating composition is aqueous and includes a binder material such as acrylic or styrene-butadiene latex, methyl- or carboxymethyl cellulose, starch or poly(vinyl alcohol).

Binder materials can be used alone or in combination, and a typical coating composition, when manufactured,
From the capsule ingredient system, strain the water until it is about 40% capsule, then add the capsule slurry to about 100%
Parts by weight and 10% poly(vinyl alcohol) solution approx.
Make in combination with 100 parts by weight.

Dyes can be used alone or in combination to obtain the desired color, and typical dyes that can be used as colorants in the production of capsules and display sprays for the coating compositions of this example are listed above. .

Combinations of different types of magnetic flakes can be used if desired or necessary.

Example 2 The composition of Example 1 is painted onto a transparent sheet of polymeric material such as polystyrene or polyethylene terephthalate, and when dry, the composition is covered with an opaque substrate layer of red enamel. In the first exemplary shutter, the composition was applied to a thickness of approximately 43 microns when dry. The dry thickness corresponds to a total coating weight of about 25 pounds per series and an active coating weight of about 20 pounds per series. The dry film thickness of the composition of Example 1 was approximately
Represents a magnetic flake concentration of 3.8 pounds. As specified in Example 1, the flakes used in this example have a theoretical shielding of about 1.2 pounds per series; and the flakes of this coating have a shielding of about 3.8 pounds per series. The shielding ratio in this example is approximately 3.2.
When viewed through the transparency, this first example shutter exhibited a bright red color when in transmission mode and a deep yellow-gold color when in reflection mode. When the display's shutter was partially reflective and partially transmissive, there was a noticeable contrast between the yellow-gold and red colors.

In a second exemplary shutter, the composition is
The coatings were applied to a dry thickness of 36 microns (approximately 12 pounds active coating weight per series). The corresponding shielding ratio is about 1.9, and when viewed through a transparent sheet,
This second exemplary shutter exhibited a bright red color when in transmissive mode, and was substantially the same shade as the first exemplary shutter when in transmissive mode. However, when in the reflective mode, this second exemplary shutter exhibited a mixed red and yellow hue, without the strong red-gold contrast of the first exemplary shutter in the reflective mode. The flakes do not adequately shield the substrate.

In a third exemplary coating, the composition was applied to about 70%
Coatings were applied to a dry thickness of microns (approximately 33 pounds active coating weight per series). The corresponding shielding ratio is approximately 5.3. This third exemplary device exhibited a yellow-gold color when viewed through a reflective transparent sheet. When this third exemplary coating was placed in what was previously referred to as transmission, however, a dark gold color (black-gold color) was exhibited. The dark gold color, with virtually no red color visible, indicates that the projected light did not pass through the film and was absorbed there. Therefore, if the coating is too thick, more of the projected light will be absorbed than transmitted, the transmission will become absorption, and the coating will become a light trap rather than a shutter.

Several additional exemplary shutters were made with various coating weights, and the results of testing of the exemplary shutters resulted in the accompanying figures.

Neither the thin coating (second example) nor the thick coating (third example) resulted in an increase in contrast due to the difference in hue. If the coating is too thin, the color of the base will be dominant, and if the coating is too thick, the color of the paint will be dominant. In particular, there is no correlation of different shades unless the colorant concentration and magnetic flake shielding comply with the critical conditions of the present invention.

It should, of course, be understood that the narrow coating weight range is critical to the concentration or density of magnetic particles used therein. The basic decisive parameters for making a shutter display effective are:
It is the planar area of magnetic particles per unit area of the display surface, previously defined as the shielding ratio. about
We have found that only shielding ratios from 2.0 to about 4.75 produce visually pleasing shutter display.

Example 3 The coating composition of Example 1, except that the capsule-containing colorant is a phthalocyanine green microdispersed pigment, used at a concentration of about 2% based on oil, and has an average particle size of about 0.1 micron. was manufactured again.

Displays made using this composition exhibited the same critical paint weight range for shutter effect as found in Example 2 above using dissolved dyes.

Example 4 In this example, the coloring material is oil yellow.
NB (P-diethylaminoazobenzene, color index 11021), which is a capsule ingredient.
1.4%, and the magnetic material is International Nickel CO., Inc.
,) from Huntington, West Virginia
Metallic nickel flakes commercially available under the trade name BM-155-5A (aspect ratio is approximately 40, longest dimension is approximately
A coating composition was prepared in the same manner as in Example 1, except that the coating composition was 40 microns). The magnetic flakes are about 20% of the encapsulated component. The oil to be encapsulated was selected from those mentioned in Example 1. The composition,
A flexible transparent film, such as a 3 mil thick polyethylene terephthalate film, was coated with an amount such that the flake shielding ratio in this coating was approximately 3.2. Dry coatings on transparent films can be used with a variety of substrate elements to provide effective color shutter elements.

When the shutter element is placed on a substrate printed with a different shade of color than the colorant in the shutter element, a complete shutter display is created. The shutter element was placed on a printed substrate sheet with green text. When using the reflective type, the printing on the substrate was not visible. When in transmission, the print on the substrate was clearly visible through the shutter element. The comparative shade difference between the shutter element colorant and the printing colorant is
It provides outstanding subjective visual contrast, resulting in an improved display of the print.

The effectiveness of the display of this embodiment is enhanced by placing the substrate print on a substrate substrate having a hue as close as possible to that of the colorant of the shutter element.
In fact, the unprinted substrate portions visible through the transmission shutter had the same appearance as the reflection shutter.

The shutter effect and therefore the value of the display is lost when the coating is not within a satisfactory range. When the coating weight is very light, the substrate printing is always easy to see; when the coating weight is very heavy, the substrate printing is difficult to see, no matter what type of shutter the shutter is.

Example 5 In this example, a coating composition is made using capsules made by the preferred method previously disclosed, separated from the making vehicle, and dried. The capsules, with an average diameter of about 40 microns, contain about 84% oily internal phase dispersion consisting of about 2% colorant, 19% magnetic flakes, and the remainder mineral oil as an oily liquid. The coloring material is a green microdispersed pigment such as phthalocyanine green and has an average particle size of about 0.1 micron. The magnetic flakes have an aspect ratio of approximately 16 and the longest length is approximately
It is 40 micron nickel. To make the coating composition, the capsules are dispersed in a solution of 5% ethylcellulose in toluene as the solvent, making the capsules 25% of the composition.

The present compositions are used in the same manner as the compositions of the previous examples. from 2.0 per square meter for the color shutter display elements described in this application.
A coating of one shade that provides flat surface coverage within a defined area of 4.75 square meters is an embodiment of the invention when used with a substrate having a different shade.

Example 6 In this example, the coating composition of Example 5 was spray-coated onto a black-painted molded body. The coating thickness is adjusted to 1-3 mils to provide coverage of the flat surface within the specified range. The shutter effect of this example was the same as that of the previous example.

Example 7 In this example, a transparent film with a substrate tint was used to make a shutter display. A magnetic flake capsule coating composition, such as the yellow composition of Example 1, is coated onto a transparent carrier sheet at a coating weight such that the dry film magnetic flake shielding ratio is from 2.0 to 4.75. The capsule coating is then sequentially coated with a colored lacquer, such as nitrocellulose, containing an oil blue dye dissolved in a suitable organic solvent. When projected onto the capsule side of the display and the white light is reflected from the display in a reflective manner, the reflected light has a yellow tint. On the other hand, if the display is of a transmission type, the reflected white light will have a green tint.
The brightness of the green tint is enhanced by placing a highly reflective surface on the lacquer side of the display.

[Brief explanation of the drawing]

Figure 1 shows the relationship between active coating amount and Hunter value. FIG. 2 shows the relationship between the difference in Hunter value and the amount of active coating between the reflective type and the transmission type. FIG. 3 shows the relationship between the amount of active coating and the color purity of reflected light in the reflective type and the transmission type. FIG. 4 shows the relationship between the amount of active coating and the dominant wavelength of reflected light from the reflective type and the transmissive type.

Claims (1)

[Scope of Claims] 1. (a) a large number of substantially spherical microcapsules containing a liquid and magnetic flakes, and (b) a coloring material (c) a substantially transparent substance surrounding (a) and (b). a magnetically responsive, reversible shutter film made of a polymeric binder material, wherein the microcapsules have a total particle flat surface area of the magnetic flakes that is 2.0 to 4.75 times the area of the shutter film. a magnetically responsive, reversible shutter film present in the shutter film in an amount.