JP2003270678A - Sheet type display device and method of manufacturing the same - Google Patents

Abstract

(57) [abstract] (with correction) [PROBLEMS] To produce a resin composition particle,
Pulverization, resin composition that is easy to spheroidize, spherical, light,
Resin composition particles excellent in responsiveness of migration and rotation, sheet-type display devices using the resin composition particles, excellent in display response and memory properties, suitable for these resin composition particles and sheet-type display devices A simple manufacturing method. SOLUTION: From a resin composition containing a thermoplastic resin, a wax, and a coloring agent as required, and excluding the coloring agent and having a specific gravity of less than 1, subjected to sheeting, pulverization and spheroidizing treatment, Get the particles. The display can be performed by rotating and / or migrating the resin composition particles in a space or the like in the sheet. The amount of the wax is preferably more than 100 parts by weight based on 100 parts by weight of the thermoplastic resin in the resin composition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet type display device for displaying by rotating and / or migrating resin composition particles in a sheet by the action of an electric field, and resin composition particles and a resin used therefor. The present invention relates to a composition and a method for manufacturing these devices and resin composition particles. For more details,
The present invention relates to a technique in which the resin composition particles are produced through melting, blending, pulverizing and spheroidizing treatments.

[0002]

2. Description of the Related Art Conventionally, there has been proposed a display device called an electronic paper, a paper-like display, a digital paper, etc., which displays an image by changing optical absorption or reflection by an electric field.

This display device is extremely stable against changes in temperature and electrical noise, and has a memory property capable of maintaining display even when power supply is stopped.

Further, since the display is made by utilizing the reflection / scattering of natural light, it is an ideal display device capable of suppressing eye strain caused by the flicker of the light source such as seen in a liquid crystal device or a cathode ray tube.

As an element used in such a display device for changing optical absorption and reflection by an electric field, electrophoretic particles having a combination of hemispheres having different colors and electrical characteristics are used as dielectric elements. Microcapsules encapsulated with a liquid, as in JP-A-01-086116, a solvent in which electrophoretic particles are dispersed is colored, and microcapsules encapsulating the solvent, a liquid crystal containing a dichroic dye and a smectic liquid crystal / There are polymer composite membranes.

These methods are expected as a substitute for paper because they have a memory property, can retain image information without a power source, and are reflection type display devices.

Since the device may be coated on a PET (polyethylene terephthalate) film having an electrode,
A thin, light, and bendable sheet-type display device can be provided.

In particular, US Pat. No. 4,126,854,
Also, the display medium described in each of the specifications of Nos. 4,143,103 and using the hemispheres of electrophoretic rotating particles divided into different colors and charging characteristics has an excellent contrast as compared with other methods. Known as a characteristic display.

As shown in FIG. 1, this display medium has a plurality of voids 2 filled with a dielectric liquid, and a substrate 3 which is an optically transparent layer, and electrophoretic rotating particles 1 in the voids 2. The structure has

Further, since the electrophoretic rotating particle 1 has two surface regions having different colors and different charging characteristics in one particle, when an electric field is applied, as shown in FIG. Then, an image can be displayed.

In FIG. 2, (a) is before application of an electric field,
(B) shows the state after the electric field is applied, and (c) shows the state after the voltage is applied.

In FIG. 2A, the electrophoretic rotating particle 1 is located below the void 2. The electrophoretic rotating particle 1 is composed of hemispherical portions 4 and 5 having different colors.

Here, when an electric field is applied, the hemispherical portion 4
Is positively charged, and the hemispherical portion 5 is easily negatively charged.

In this case, when an electric field is applied so that the upper electrode is negative, the electrophoretic rotating particles 1 rotate while migrating upward as shown in (b) as the electric field is applied, and eventually as shown in (c). With the hemisphere part 4 facing upward,
Reach the top of. In this state, the sheet type display device can display.

Particles capable of such migration and / or rotation are hereinafter referred to as migration rotating particles. That is, the invention of the present application relates to movements such as migration, rotation, and combination of migration and rotation of particles, and the migration-rotating particles are used in this sense.

For example, generally, particles having a function of vertically migrating in a sheet, particles having a function of vertically migrating in a void in a sheet, particles having a function of rotating in a void in a sheet, Particles or the like having a function of rotating while moving up and down in the voids in the sheet can be used in the sheet-type display device according to the present invention, and migration rotating particles may include all of such cases. Is. However, it may be limited to only a part of the above functions from the context.

As the method and material for producing such electrophoretic rotating particles, (1) Carnauba wax, carbon black and titanium dioxide as described in US Pat. No. 5,262,098 are used, and (2) Japanese Patent Laid-Open No. 11-8506, in which two types of melted wax particles different in particle size are combined, spherically shaped by surface tension and then solidified.
No. 7, JP-A-11-85068, a method of vapor-depositing metal, carbon black, antimony sulfide, etc. on the surface of particles of glass, resin, etc., (3) JP-A-11-85069, JP-A-11-85069 11-161206, zinc oxide is used as a material, and a particle is formed from a photosensitive material using a toner as a color former, and a color is developed by exposure, development, and fixing treatment, for example, a hydrophilic polymer is a halogen as a color former. Those to which silver halide is added have been proposed.

Further, for example, when a resin is used,
A method for producing particles by producing a rolled sheet in which two colored resins are stuck together by a roller or a press and then crushing and heat-treating with hot air is disclosed in JP-A-01-2825.
It is proposed in Japanese Patent Publication No. 89.

On the other hand, as the electrophoretic rotating particles, Japanese Patent Publication No.
JP-A-015115 and the like propose a method in which a dye, a dielectric liquid, and titanium dioxide as electrophoretic rotating particles are enclosed in a cell constituted by electrodes. However, in this method, problems such as fading of the dye on the electrode and aggregation of titanium oxide occurred.

After that, in summary in Japanese Patent Application Laid-Open No. 01-086116, as shown in FIG. 3, titanium oxide as the electrophoretic particles 1 and the dielectric liquid 6 colored with a dye are placed in the voids of the microcapsules 7. A method of encapsulation was proposed to solve the above problems. Examples of methods for preparing microcapsules include a phase separation method, an interfacial polymerization method, an insolubilization reaction method, and the like.

Further, in JP-A-5-317805, a phase separation method, particularly a gum arabic / gelatin complex coacervation method is used.

Further, in US Pat. No. 5,961,804, as shown in FIG. 4, two kinds of electrophoretic particles 1 having different colors are dispersed in a void 2 filled with a dielectric liquid to generate an electric field. There is also proposed a method of displaying by causing each particle to migrate in different directions by application of. In this method, a pigment or a pigment coated with a resin is electrophoresed by an electric field.

[0023]

In a display device using electrophoretic rotating particles, it is effective that the specific gravity of the particles is small in order to maintain a display even in the absence of an electric field. It is also advantageous in terms of responsiveness of migration and rotation, which means how quickly the migration and rotation depend on the application of an electric field. In particular, when it is almost equivalent to the dielectric liquid (specific gravity 0.8 to 1.1), the memory property and the responsiveness of migration and rotation are very high.

However, the electrophoretic rotating particles are often colored in one or two colors, and when a pigment having a large specific gravity such as titanium oxide is blended and used as the colorant, the electrophoretic rotating particles are colored. Specific gravity often increases.

Therefore, it is desirable that the resin component constituting the electrophoretic rotating particles has a specific gravity as small as possible.

A thermoplastic resin is preferable as the resin having a small specific gravity. As the thermoplastic resin, a polyolefin-based polymer or a blend thereof is preferable, and particularly polyethylene (low-density polyethylene has a specific gravity of 0.92 to 0.9).
3. Specific gravity of high density polyethylene is 0.94 to 0.95)
Polypropylene (specific gravity 0.9 to 1.0) is effective.

However, thermoplastic resins typified by polyethylene and polypropylene often have problems in the production of electrophoretic rotating particles.

First, in order to produce a large amount of electrophoretic rotating particles, a method of crushing a resin or a resin composition and then subjecting it to heating, classification, or the like is used. Thermoplastics typified by polyethylene and polypropylene are used. Resins generally have problems that they are not easily pulverized and it is difficult to reduce the particle size.

Further, there is a problem that exceptionally crushable high density polyethylene or the like has a high melt viscosity and is hardly spheroidized by spheroidizing treatment by heating.

In order to reduce the specific gravity, it is important to reduce the addition amount of the inorganic pigment such as titanium oxide as much as possible. However, such reduction in the addition amount often makes pulverization more difficult. Therefore, the above problem is more serious.

The present invention solves these various problems, and when producing resin composition particles, it is easy to form a sheet, crush, and spheroidize, and is spherical and light, and has a responsiveness to migration and rotation. A resin composition capable of forming or forming excellent resin composition particles, a sheet type display device having excellent display responsiveness and a memory property, and further, such a resin composition particle or sheet type display device effectively It is intended to provide a method of manufacturing.

Still another object and advantage of the present invention are:
It will be apparent from the following description.

[0033]

According to the present invention, in a sheet type display device for displaying by rotating and / or migrating resin composition particles in a sheet by the action of an electric field, the resin composition particles are Thermoplastic resin and wax,
Provided is a sheet-type display device which is made of a resin composition optionally containing a colorant and has a specific gravity of less than 1 excluding the colorant.

10 of the thermoplastic resins in the resin composition
The amount of wax is preferably more than 100 parts by weight based on 0 parts by weight.

Further, according to the present invention, in the method for manufacturing such a sheet type display device, the resin composition particles are melt-blended with a thermoplastic resin and a wax to form a resin composition, and the resin composition. A step of molding the composition into a sheet, a step of crushing the sheet to form a small piece of the resin composition (also referred to as a resin composition piece in the present specification), and heating the resin composition piece, A method of manufacturing a sheet type display device manufactured by a method including a step of spheroidizing.

In the step of melt-blending the thermoplastic resin and the wax to form a resin composition, a colorant is blended with the thermoplastic resin to form a blend, and then the wax is added to the blend. It is preferable that it is a stage of further blending.

By these techniques, when the resin composition particles are produced, the resin composition particles can be easily formed into a sheet, pulverized or spheroidized, and are spherical, light and excellent in responsiveness to migration and rotation. It is possible to obtain a sheet-type display device which is excellent in display responsiveness and memory property.

Further features of the present invention will be clarified in the embodiments of the invention and the drawings described below.

[0039]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings and examples. It should be noted that these drawings, examples, and explanations are merely illustrative of the present invention and do not limit the scope of the present invention. It goes without saying that other embodiments may belong to the scope of the present invention as long as they match the gist of the present invention. In the drawings, the same parts are designated by the same reference numerals.

The resin composition forming or capable of forming the resin composition particles according to the present invention contains a thermoplastic resin, a wax, and optionally a coloring agent, and the specific gravity of the resin composition excluding the coloring agent is 1 It is smaller.

This resin composition may contain a colorant in addition to the thermoplastic resin and the wax. Further, finally, although it is in the form of particles as the resin composition particles, in addition, in the case of an amorphous shape as the resin composition piece before the spheroidizing treatment described later, the resin composition piece is obtained by pulverization. In the case of a sheet-like material, the sheet may have various forms such as an arbitrary shape before obtaining the sheet.

The "sheet form" in this case also includes a laminated sheet having a two-layer structure, as described later.

The resin composition particles according to the present invention are
Particles produced from this resin composition, which rotate and / or migrate under the action of an electric field.

This resin composition facilitates the production of the above-mentioned sheet, the crushing thereof, and the spheroidizing of the resin composition pieces obtained by the crushing. Further, the resin composition particles are spherical and light, and have excellent responsiveness to migration and rotation.

The thermoplastic resin used in the present invention is a component that constitutes a resin composition together with wax,
It is for finally giving the resin composition a shape as particles.

The thermoplastic resin is not particularly limited,
Those having good compatibility with the wax are preferable. When the compatibility is poor, uniform blending becomes difficult, and the two phases may be separated or the wax may exude (bleed out) after blending, which is not preferable in many cases.

This compatibility can be judged by the solubility parameter. That is, the difference between the solubility parameter of the thermoplastic resin and the solubility parameter of the wax is
It is preferably 0.2 or less. If it is larger than 0.2, the wax and the resin may be separated or the sphericity may be insufficient.

The compatibility is sufficient if the two phases are not separated and visible when observed under a microscope at a magnification of about several tens of times after blending with the thermoplastic resin. If it is difficult to see, pigments may be mixed in advance with either the thermoplastic resin or the wax and blended.

As the thermoplastic resin which can be used, a polyolefin-based polymer and a blend thereof are preferable, and polyethylene, polypropylene, a copolymer thereof and a blend thereof are particularly preferable.

In all cases, the specific gravity is low and the compatibility with wax is often good.

In particular, polyethylene and polypropylene having a small specific gravity are preferable because it is easy to obtain those having stable quality.

The polyolefin-based polymer also includes a copolymer.

There are various kinds of copolymers such as random copolymers and block copolymers, and if these are taken into consideration, there are a wide variety of blends.

Among these various kinds of thermoplastic resins, which is the most suitable for practical use of the present invention, compatibility with wax, specific gravity, and coloring pigment are added. In this case, it can be easily determined by observing the dispersed state of the pigment.

Specific examples of polyethylene include various high-density polyethylenes and low-density polyethylenes. For example, Tosoh Corporation's trade name Petrosen can be mentioned.

Specific examples of polypropylene include various polypropylenes. For example, Novalak from Mitsubishi Chemical Corporation.

In the present invention, the main steps of giving the thermoplastic resin a shape as particles are crushing treatment and spheroidizing treatment, but the wax according to the present invention is used in order to improve the efficiency of this crushing treatment. It is useful for enabling the chemical treatment.

The wax is hard in the unmelted state and can be ground into a composition with a thermoplastic resin.
Since it melts at a relatively low temperature, its melt viscosity is low, and even a part of the thermoplastic resin is dissolved, it is easy to mold the resin composition particles into a spherical shape. Thermoplastic resin 1
When the amount of the wax exceeds 100 parts by weight with respect to 00 parts by weight, the efficiency of pulverization is improved. The amount of the wax is more preferably more than 200 parts by weight with respect to 100 parts by weight of the thermoplastic resin.

The upper limit is not particularly limited,
For 100 parts by weight of the thermoplastic resin, 9 parts of the wax
If the amount is more than 00 parts by weight, the strength of the resin composition particles becomes insufficient, and problems such as breakage easily occur.

In the case of using an inorganic pigment as a colorant, if the content of the pigment is lowered in order to lower the specific gravity of the resin composition, the pulverization efficiency may be lowered. Therefore, the role of wax in the present invention. Is important.

Unless the object of the present invention is violated, in the present invention, the wax is fragile in the solid state, melts at a relatively low temperature, and shows a low-viscosity liquid regardless of animal, plant, or synthetic product. It includes fatty acids, alcohols, esters of fatty acids and alcohols, and saturated hydrocarbons with a high degree of polymerization, called waxes or waxes.

This includes solid esters represented by esters of higher fatty acids such as spermaceti, beeswax and cinnamon wax with higher monohydric alcohols, as well as petroleum products such as paraffin synthetic wax which is one of petroleum products. Wax and wax could also be included.

Of these, paraffin-based synthetic wax is preferable because stable quality is easily obtained.

An example of the paraffin-based synthetic wax is ethylene wax.

Specific examples of the ethylene wax include High Wax 100P, High Wax 200P, High Wax 210P and High Wax 22 under the trade name of Mitsui Chemicals, Inc.
0P etc. can be mentioned.

It is preferable that the specific gravity of the resin composition excluding the colorant is less than 1 because the resin composition can be hardly affected by the gravity when it is held in the dielectric liquid, and therefore the storage stability of the position in space is excellent. Because. Such excellent storage of the position in the space improves the memory property of the image shown when used in a display device or the like.

If there is a slight difference from the specific gravity of the dielectric liquid, the resin composition particles will eventually float or settle. Due to the design of the display device, it is preferable that the display device sinks rather than floats.

From this meaning, the specific gravity of the resin composition particles is
It may be preferable to add the additional condition that the specific gravity of the surrounding dielectric liquid is equal to or higher than that of the surrounding dielectric liquid.

Generally, when the specific gravity of the resin composition or resin composition particles is high, it is necessary to increase the specific gravity of the dielectric liquid. A halogen-containing compound is often used in order to increase the specific gravity of the dielectric liquid. Halogen-containing compounds are generally carcinogenic and also volatile, and are therefore often unfavorable in terms of environmental hygiene.

In this respect, the use of the resin composition or the resin composition particles according to the present invention has an advantage that it is not necessary to use such a halogen-containing compound.

In connection with the crushing treatment of the resin composition described later, it may be preferable that the Izod impact strength of the resin composition at −50 ° C. is in the range of 0.5 to 30 J / m. If it is higher than 30 J / m, the pulverization treatment efficiency may decrease. On the other hand, if it is less than 0.5 J / m, the variation in size of the resin composition piece becomes large, which is not preferable in some cases.

The amount of the wax is preferably more than 100 parts by weight with respect to 100 parts by weight of the resin in the resin composition. This is because if the amount of wax is 100 parts by weight or less, the efficiency of pulverization processing often decreases.

A comparison of the pulverization treatment efficiency is made, for example, by
It can be determined by how long it takes to complete processing up to a predetermined size.

The wax in the present invention has a melting point and has a low viscosity in a molten state, and the viscosity is preferably in the range of up to 1000 mPa · s. This is because when such a wax is used, the spheroidizing treatment described later proceeds smoothly. This viscosity is JIS
It can be measured according to K 6862.

The coloring of the resin composition or resin composition particles is not particularly limited, and either dyes or pigments can be used, but the method of blending the pigment with the thermoplastic resin and wax is stable. Quality is easy to obtain, which is preferable.

Examples of white pigments include titanium dioxide of anatase and rutile type, barium titanate, light,
Known pigments such as heavy calcium carbonate, alumina, zinc oxide, zinc sulfide, antimony oxide, lead sulfate, and silicon dioxide can be used.

In order to increase the whiteness, it is desirable to use titanium dioxide having a high hiding ratio and a particle size of 100 to 300 nm.

As the black pigment, known pigments and dyes such as carbon black, magnetite, aniline black, and complex oxides of copper, cobalt, iron, manganese, chromium and the like can be used.

Further, in order to improve dispersibility and prevent discoloration of the resin, the pigment may be surface-treated with an inorganic substance, a silane compound, a resin or the like.

In addition to pigments and dyes, tricalcium phosphate, in order to control electrical characteristics such as ζ potential of particles,
Inorganic substances such as calcium salts such as calcium chloride and calcium oxide, and surfactants such as metal soap, nonionic, anionic, cationic and amphoteric may be appropriately mixed.

Colorants other than white and black include 1) azo pigments such as soluble azo pigments, monoazo pigments and disazo pigments, and (2)
Examples include polycyclic pigments such as phthalocyanine-based, quinacridone-based, periline-based, perinone-based, and isoindoline-based pigments.

The resin composition particles according to the present invention are
In order to enable display on a sheet-type display device, it is often colored in one color as shown in the example of FIG. 4 or in two colors as shown in FIG.

The above-mentioned "specific gravity is less than 1" relates to the whole in the case of such particles which are entirely colored with one color or two colors.

When pigments of different colors are used and colored in two colors, if the specific gravity is different for each of the spheres forming the different surface regions, the sphere having either color is used. In many cases, it is not preferable because a problem that the portion tends to be on the upper side occurs, and the above-mentioned memory property and migration and rotation responsiveness are impaired. Therefore, it is desirable that the specific gravities of the two spherical portions be as close to each other as possible.

Next, as an example of a method of manufacturing the resin composition particles and the display device according to the present invention, resin composition particles (including two different colors containing a thermoplastic resin and a wax) having different surface regions ( In the specification of the present application, a method for producing (also simply referred to as bicolor particles) and a method for producing a display device using the resin composition particles will be described in detail.

First, a thermoplastic resin, a wax and a colorant are blended to prepare a resin composition having two different colors.

The method of blending the thermoplastic resin, the wax and the colorant includes a method of blending all of them at the same time, a method of blending two of them, and a method of blending the other one, and a method of increasing the colorant. Various methods such as a method using a thermoplastic resin or wax contained in the concentration (masterbatch method) can be adopted, but first, the thermoplastic resin and the colorant are blended, and the wax is blended with this blended product. The method for obtaining the resin composition is preferable because the dispersion state of the colorant is often better than the method in which the thermoplastic resin and the wax are first blended.

As a method of blending the thermoplastic resin and the colorant to obtain a blended product, a method of kneading using a device such as a roll mill, a kneader, an extruder or a homogenizer is suitable.

Then, when a wax is blended with this blended product, a roll mill, a kneader, an extruder, a homogenizer or the like can be used.

In any case, heating is appropriately performed if necessary.

Then, the resin composition is molded into a sheet. In order to produce the two-color particles by crushing, as shown in FIG. 5, two resin compositions having different colors are laminated in a sheet form.

The different surface areas of the resin composition particles can be produced from the lamination of these two sheets.

In order to laminate in a sheet form, the resin composition is melted, the melt is extruded into a sheet form and laminated, or the melt is gradually spread into a sheet form by a rolling roll or the like. A method of laminating with a heating / pressing press can be used. In many cases, the resin composition according to the present invention does not have sufficient tensile strength when it is spread, so the method using a rolling roll or a pressure press is often preferable.

Then, this sheet is crushed to prepare a resin composition piece.

As a method of crushing the sheet, any known method can be adopted as long as it does not violate the gist of the present invention.

For example, a method of dry pulverization such as a jet mill or a centrifugal mill, or a method of wet pulverization such as a ball mill or a dyno mill can be mentioned.

A low-temperature pulverization method of pulverizing by cooling with liquid nitrogen can be preferably used.

The purpose of pulverizing the resin composition laminate is to make the resin composition laminate into resin composition pieces prior to producing the resin composition particles.

The shape of the resin composition piece is not particularly limited and is often an angular irregular shape. However, in order to obtain resin composition particles having uniform properties, the size of the resin composition piece should be within a predetermined range. It is preferable to align them.

The apparatus used for the above pulverization method is often equipped with parts such as a simple sieve having the function of making the particle diameters uniform, but it is used for the sheet type display apparatus according to the present invention. Is often inadequate for

Therefore, in such a case, techniques such as sieving, centrifuging, wet or dry classification for uniformizing the particle size can be adopted. For example, decantation and the use of cyclones.

The particle size (diameter) of the resin composition particles according to the present invention is preferably 200 μm or less,
It is more preferably between 100 μm. Therefore, the size of the resin composition piece can be adjusted and selected so that the sphere-converted particle size falls within such a range. The spherical equivalent particle size is
It can be determined as a sphere-equivalent particle diameter by volume using a Coulter counter.

However, since the same particle size adjustment and selection can be performed at the resin composition particle stage, at the resin composition piece stage, the particle size adjustment is not selected and the resin composition particle size is not selected. It is also possible to adjust and select the particle size only in the step, or in the step of the resin composition piece, to select and adjust the particle size in the first step, and in the step of the resin composition particle, to adjust the particle size in the second step, It is also possible to make a selection.

Then, the resin composition piece is heated to be spherical.

Examples of the heating method for spheroidizing include hot air treatment and heating with water, silicone oil or the like. When the resin composition piece is exposed to hot air or immersed in heated water or silicone oil, the resin composition melts and becomes spherical due to surface tension.

The resin composition according to the present invention melts at a relatively low temperature because the thermoplastic resin is partially dissolved in the wax. In order to sufficiently exert this effect, the wax in the invention of the present application has a melting point and has a low viscosity in a molten state, and the viscosity is up to 100.
It is desirable to be in the range of 0 mPa · s. This is because melting and spheroidizing treatment of the resin composition according to the present invention become easier.

Finally, the spherical particles thus obtained are collected by filtration, precipitation, centrifugation, etc., washed and dried to obtain bicolor particles.

At this stage, a process for making the particle diameters uniform may be performed. In such a case, as in the case of the resin composition piece, techniques such as sieving, centrifugation, wet or dry classification, etc. can be adopted.

According to the method for producing resin composition particles according to the present invention, which comprises using the composition according to the present invention having various characteristics as described above and producing the resin composition particles as described above, It can be easily produced by a known method, and a resin composition piece can be easily produced by pulverizing this.
Furthermore, resin composition particles having excellent sphericity can be easily produced from this resin composition piece.

The sheet type display device according to the present invention can be manufactured by filling the voids inside the substrate with the dichroic particles and the normally transparent dielectric liquid.

As a method of filling the voids inside the substrate with the two-color particles and the dielectric liquid, (1) US Pat. No. 4,143,
No. 103, a method of dispersing two-color particles in silicone rubber before curing, curing the silicone rubber, and swelling the silicone rubber with silicone oil, (2) "A Newl"
y Developed Electrical Tw
isting Ball Display, "M.I. Sa
itoh et. al. : Proc. of SI
D, Vol 23 / 4.1982, two-color particles are coated with a toluene-soluble thermoplastic resin, dispersed in polyvinyl alcohol, cured, and then immersed in toluene.
(3) By using the interfacial polymerization described in JP-A-8-234686, a dielectric liquid and two-color particles are covered with a thermoplastic resin film to form microcapsules, and the microcapsules are placed in a transparent resin. A method of dispersing is included.

As a method for producing the microcapsules, known methods such as an interfacial polymerization method, an in situ polymerization method and a complex coacervation method are used.

The microcapsules are dispersed in a known resin such as polyvinyl alcohol or silicone rubber, and PE
A display device can be manufactured by applying it to a T film or the like and providing a counter electrode. Alternatively, the electrophoretic particles and the dielectric liquid may be enclosed in a cell having a counter electrode.

By using mineral oil, animal oil, vegetable oil or dimethyl silicone as the dielectric liquid, a highly safe sheet type display device can be provided. More specifically, there are isoparaffin, oleic acid, linoleic acid, olive oil, castor oil, soybean oil and the like. In some cases,
In some cases, it is possible to use an organic solvent such as toluene or acetone or pure water.

Whether or not it is suitable as a dielectric liquid is, for example, that migration of particles can be increased by making the charge amount larger than that of other dielectric liquids, and that components in particles are difficult to extract. It can be mentioned that it is difficult for the body fluid to be transferred from the space filled with the body fluid into the base material which is the outside thereof. These can be selected by trial and error in a model experiment.

The sheet-type display device thus manufactured is excellent in display response and its memory property.

FIG. 6 is a model diagram showing a cross section of an example of the sheet type display device according to the present invention. In FIG. 6, the void 2 containing the electrophoretic rotating particles 1 and the dielectric liquid 6 is the base material 3
Exists inside.

A grid-like transparent electrode 8 is formed on the base material 3.
However, there is a grid-shaped electrode 9 that is orthogonal to the grid of the transparent electrode 8, and these are sandwiched by the substrates 12 and 13. The substrate 12 is transparent to allow visual inspection 15.

When a voltage is applied from the power source 14 in this state, the electrophoretic rotation occurs as shown in FIGS. 2 (a) to 2 (c),
Display the statue.

This image is retained even after the voltage application is stopped.

Although the two-color particles have been described above, the particles are made of a resin composition containing a thermoplastic resin and a wax, which is used for a sheet type display device utilizing the migration of particles, and has a surface area of one color. In the case of resin composition particles (also referred to simply as one-color particles in the present specification), almost the same steps can be adopted.

In the case of one-color particles, the spheroidizing treatment cannot be said to be essentially necessary treatment, but it is effective for increasing the contrast of the display device. The spherical shape facilitates aggregation of electrophoretic particles due to a reduction in frictional resistance, a reduction in contact area, etc., and thus the electrophoretic particles completely cover the display surface side of the display device, and the contrast is improved.

To use one color particles as electrophoretic particles,
Encapsulate in microcapsules with dielectric liquid.

Further, as shown in FIG. 3, a display device can also be manufactured by encapsulating two types of electrophoretic rotating particles of different colors in microcapsules or cells.

[0125]

EXAMPLES The present invention will now be described in more detail with reference to examples.

The physical properties and the like were measured by the following methods.

(Viscosity) The viscosity was measured according to JIS K 6862.

(Particle Size) The sphere-converted particle size of the resin composition piece was determined as a sphere-converted particle size (sphere equivalent diameter) by volume using a Coulter counter manufactured by Beckman Coulter, Inc.

The average particle size of the resin composition particles is CLS-1.
(Manufactured by Garai Co., Ltd.) and using a microscope, the light-shielding method was used.

(Trueness) Beckman Coulter Co., Ltd.
An image of the particles was taken using a Coulter counter manufactured by Co., and the shape factor was measured by image analysis. When the shape factor was 1.0 to 1.1, it was determined to be a true sphere.

The low-density polyethylene resin has a specific gravity of about 0.92, and the high-density polyethylene resin has a specific gravity of 0.92.
4. The specific gravity of wax was about 0.95, and the specific gravity of polypropylene was 0.92.

Example 1 32 parts by weight of a low density polyethylene resin (melt index 150) was kneaded with 20 parts by weight of titanium dioxide by a roll mill.

This blend was rolled using a roll mill.
A white resin composition was prepared by diluting in a molten state with 48 parts by weight of ethylene wax (melting point: 125 ° C., viscosity: 27.5 mPa · s at 140 ° C.). Its specific gravity was 1.08.

On the other hand, 24.25 parts by weight of a low density polyethylene resin (melt index 150) was kneaded with 1 part by weight of carbon black and 18 parts by weight of magnetite by a roll mill.

Then, this blend was diluted in a molten state with 56.75 parts by weight of ethylene wax (melting point: 125 ° C., viscosity at 140 ° C .: 27.5 mPa · s) using a roll mill to obtain a black resin. A composition was made. Its specific gravity was 1.06.

Then, using a pressure press at a temperature of 130 ° C., a thickness of 15 μm was obtained from each of the colored resin compositions described above.
m sheets were produced.

Under pressure, the sheets are heated to a temperature of 11
By fusing at 0 ° C., a two-layer laminate including a white layer and a black layer as shown in FIG. 5 was produced.

Next, this laminate was immersed in liquid nitrogen and then pulverized using an ultrasonic homogenizer.
Although there was a distribution of μm to 120 μm, a resin composition piece having an average particle size of 50 to 80 μm by sphere conversion could be produced.

When this resin composition piece was dipped in dimethyl silicone oil heated to 150 ° C., it melted and became a spherical shape due to its surface tension, and became a two-color particle. Its specific gravity was 1.07.

Particles having a particle size of 80 μm or more and particles having a particle size of 30 μm or less were removed by sieving.

The resin composition particles were dispersed in a two-component silicone rubber, the rubber was immersed in dimethyl silicone oil (10 cst) having a specific gravity of 0.95 for 10 hours, and a counter electrode was installed to form a display device. It was made. When an electric field of 1.1 kv / mm was applied between the electrodes, the bicolor particles rotated in the void of dimethyl silicone oil.

The difference in specific gravity between the dimethyl silicone oil and the two-color particles is 0.12, and when used in a sheet type display device, good memory performance is expected.

Example 2 16 parts by weight of a low-density polyethylene resin (melt index 20) was mixed with 2 parts of titanium dioxide.
0 parts by weight were kneaded with a roll mill.

This blend was rolled using a roll mill.
A white resin composition was prepared by diluting in a molten state with 64 parts by weight of ethylene wax (melting point: 125 ° C., viscosity: 27.5 mPa · s at 140 ° C.). Its specific gravity was 1.08.

On the other hand, 16.4 parts by weight of a low-density polyethylene resin (melt index 20) was added with magnetite 18
Parts by weight were kneaded with a roll mill.

This blend was rolled using a roll mill.
A black resin composition was prepared by diluting in the molten state with 65.6 parts by weight of ethylene wax (melting point: 125 ° C., viscosity: 27.5 mPa · s at 140 ° C.). Its specific gravity was 1.06.

The colored resin compositions were each pulverized by a jet mill pulverizer to prepare resin composition particles having an average sphere-converted particle size of 3 μm by volume using a Coulter counter.

By dipping the resin composition particles in dimethyl silicone oil heated to 180 ° C., a spherical shape was obtained.

Isoparaffin having a specific gravity of 0.78 (trade name Isopar G manufactured by Exxon Chemical Co.) was used as resin composition particles.
Dispersed in such a manner that the solid content concentration becomes 3% by weight (white and black ratio 1: 1).
It was sealed in a cell provided with a counter electrode (electrode spacing 90 μm) consisting of a tin oxide) transparent electrode and a metal electrode. When a voltage of 300 V was applied between the electrodes, white and black particles migrated in different directions.

Example 3 19.6 parts by weight of polypropylene resin (melt index 60) was kneaded with 2 parts by weight of carbon black (particle size 20 nm) by a roll mill.

This blend was rolled using a roll mill.
A black resin composition was prepared by diluting in a molten state with 78.4 parts by weight of propylene wax (melting point: 135 ° C., viscosity at 180 ° C .: 5.1 mPa · s). Its specific gravity was 0.92.

The black resin composition was pulverized by a jet mill pulverizer to prepare resin composition particles having an average sphere-converted particle diameter of 3 μm by volume using a Coulter counter.

By immersing the resin composition particles in dimethyl silicone oil heated to 180 ° C., a spherical shape was formed.

The resin composition particles were dispersed in isoparaffin having a specific gravity of 0.78 (trade name Isopar G manufactured by Exxon Chemical Co., Ltd.) so that the solid content concentration was 5% by weight, and the dispersion liquid was sealed in a cell. . When 200 V was applied between the electrodes, the particles migrated.

Comparative Example 1 80 parts by weight of a low-density polyethylene resin (melt index 150) was mixed with 20 parts by weight of titanium dioxide by a roll mill.

When this blend was pulverized with an ultrasonic homogenizer, it could not be pulverized even after 1 hour, and resin composition pieces or resin composition particles could not be produced.

Example 4 The blend obtained in Comparative Example 1 was mixed with an ethylene wax (melting point: 12) using a roll mill.
Viscosity at 5 ° C and 140 ° C 27.5 mPa · s) 40
A white resin composition was produced by diluting in a melted state with 1 part by weight.

When this resin composition was ground with an ultrasonic homogenizer, it was possible to grind in 40 minutes.

[Comparative Example 2] 80 parts by weight of a high-density polyethylene resin (melt index 0.35) was mixed with 20 parts by weight of titanium dioxide by a uniaxial kneader. Then, this blend was pulverized by a sand grinder to a volume-average particle size of 1 μm using a Coulter counter.

When the particles were heated in dimethyl silicone oil, they became non-angular, but spherical particles could not be produced.

[0161]

EFFECT OF THE INVENTION The resin composition according to the present invention is easy to form into sheets, pulverize and spheroidize when producing resin composition particles, and it is spherical and light, and has responsiveness to migration and rotation. Excellent resin composition particles can be formed.

The resin composition particles according to the present invention are spherical and light, and have excellent electrophoretic and rotational responsiveness, and the sheet type display device has excellent display responsiveness and its memory property.

Further, according to the method for producing the resin composition particles and the sheet type display device according to the present invention, when the resin composition particles are produced, sheeting, crushing and spheroidizing are facilitated.

The invention shown in the following supplementary notes can be derived from the contents disclosed above.

(Supplementary Note 1) A resin composition capable of forming or forming resin composition particles that rotate and / or migrate by the action of an electric field, comprising a thermoplastic resin, a wax, and optionally a colorant, A resin composition having a specific gravity of less than 1 excluding a colorant.

(Supplementary Note 2) The resin composition according to Supplementary Note 1, wherein the amount of the wax exceeds 100 parts by weight based on 100 parts by weight of the thermoplastic resin.

(Supplementary Note 3) The resin composition according to Supplementary Note 1 or 2, wherein the thermoplastic resin is at least one selected from the group consisting of polyolefin-based polymers and blends thereof.

(Supplementary Note 4) The resin composition according to any one of Supplementary Notes 1 to 3, wherein the thermoplastic resin is at least one selected from the group consisting of polyethylene, polypropylene, copolymers thereof, and blends thereof. object.

(Supplementary Note 5) The wax has a melting point,
5. The resin composition according to any one of appendices 1 to 4, which has a viscosity at the melting point of 100 to 1000 mPa · s.

(Supplementary Note 6) The resin composition according to any one of Supplementary Notes 1 to 5, wherein the wax is a paraffinic synthetic wax.

(Supplementary Note 7) The difference between the solubility parameter of the thermoplastic resin and the solubility parameter of the wax is
7. The resin composition according to any one of appendices 1 to 6, which is 0.2 or less.

(Supplementary Note 8) A sheet-type display device which displays by rotating and / or migrating resin composition particles comprising the resin composition according to Supplementary Notes 1 to 7 in a sheet by the action of an electric field.

(Supplementary Note 9) A step of melt-blending a thermoplastic resin and a wax to form a resin composition, a step of molding the resin composition into a sheet, and a step of crushing the sheet to prepare a resin composition piece. And a step of heating the resin composition piece to make it spherical, the method for producing resin composition particles comprising the resin composition according to any one of appendices 1 to 7.

(Supplementary Note 10) The step of melt-blending the thermoplastic resin and the wax to form a resin composition is as follows.
10. The method for producing resin composition particles according to appendix 9, which comprises blending the thermoplastic resin with a colorant to form a blend, and further blending a wax with the blend.

(Supplementary Note 11) The method for producing resin composition particles according to Supplementary Note 9 or 10, wherein the sheet produced in the step of molding the resin composition into a sheet is a sheet having two layers having different colors.

(Supplementary Note 12) In the method of manufacturing a sheet type display device according to supplementary note 8, the resin composition particles are melt-blended with a thermoplastic resin and a wax to form a resin composition, and the resin composition. Sheet type display manufactured by a method including a step of molding an article into a sheet, a step of crushing the sheet to form a resin composition piece, and a step of heating the resin composition piece to be spherical. Device manufacturing method.

(Supplementary Note 13) The step of melt-blending the thermoplastic resin and the wax to form a resin composition,
13. The method for producing a sheet type display device according to appendix 12, comprising blending a colorant with the thermoplastic resin to form a blended product, and further blending a wax with the blended product while heating.

(Supplementary Note 14) The method for producing a sheet-type display device according to Supplementary Note 12 or 13, wherein the sheet produced in the step of molding the resin composition into a sheet is a sheet having two layers of different colors.

[Brief description of drawings]

FIG. 1 is a cross-sectional model diagram of a sheet-type display device using electrophoretic rotating particles that are two-color particles.

FIG. 2 is a model diagram showing a state of electrophoretic rotating particles that electrophoretically rotate by applying an electric field.

FIG. 3 is an example of a cross-sectional view of a microcapsule for a display device.

FIG. 4 is another example of a cross-sectional view of a microcapsule for a display device.

FIG. 5 is a cross-sectional view of a laminate of a resin composition of a thermoplastic resin and a wax.

FIG. 6 is a model diagram showing a cross section of an example of a sheet-type display device according to the present invention.

[Explanation of symbols]

1 Electrophoretic rotating particles 2 void 3 base materials 4 hemisphere 5 hemisphere 6 Dielectric liquid 7 microcapsules 8, 9 electrodes 12,13 substrate 14 power supply 15 Visual inspection

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C08L 101: 00) F term (reference) 4F070 AA13 AA15 AC04 AC14 AC15 AC94 AE04 AE19 DA11 DA46 DC01 4J002 AE001 AE031 AE041 BB032 BB122 DA036 DE046 DE106 DE116 DE126 DE136 DE146 DE186 DE236 DG026 DG046 DJ016 EN056 FD096 GQ00

Claims (4)

[Claims] 1. A sheet-type display device for displaying by rotating and / or migrating resin composition particles in a sheet by the action of an electric field, wherein the resin composition particles selectively contain a thermoplastic resin and a wax. A resin composition containing a colorant, and excluding the colorant has a specific gravity of 1
A smaller sheet-type display device. 2. Ten of the thermoplastic resins in the resin composition
The sheet type display device according to claim 1, wherein the amount of wax exceeds 100 parts by weight with respect to 0 parts by weight. 3. The method for manufacturing a sheet-type display device according to claim 1, wherein the resin composition particles melt-blend a thermoplastic resin and a wax to form a resin composition, and the resin. A sheet mold manufactured by a method including a step of molding the composition into a sheet, a step of crushing the sheet to form a resin composition piece, and a step of heating the resin composition piece to be spheroidized. Manufacturing method of display device. 4. The step of melt-blending the thermoplastic resin and the wax to form a resin composition comprises blending the thermoplastic resin with a colorant to form a blend, and then adding the blend to the blend. The method for manufacturing a sheet type display device according to claim 3, further comprising blending wax.