DE2255102A1 - PROCESS FOR ENCAPSULATING A LIQUID, SEMI-SOLID OR SOLID CORE MATERIAL IN A SHELLING MATERIAL - Google Patents

Description

November 10, 1972

■ ρ 4970

Patent attorneys

D! Pl.-Ing. A. Grönecker 2255102

Dr.-hp H. Xlnkefdey
D. f.-Ing. W. Stook / nair
äilit43

Xerox Corporation
Xerox Square, Rochester, Few York 14-603, USA

Method for encapsulating a liquid, - semi-solid or solid core material in a shell material

The invention relates to a method for encapsulating a liquid, semi-solid or solid core material in a shell material; it relates in particular to a method for Encapsulating the substantially soluble portion of a core material in the substantially soluble portion of a Shell material, the solubility of which is different from the solubility of the core material ..

The invention is described below with reference to the manufacture of electrostatographic developer materials, in particular special materials, but is not restricted to this field of application

The creation and development of images on the surface vcn - ', iiotokond-active materials by electrostatic means

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is known per se. That in U.S. Patent 2,297,691 basic electrostatographic imaging processes described is that you have a photoconductive insulating layer with a uniform electrostatic Charges, exposing the electrostatically charged layer to an image of light and shadow in order to dissipate the electrostatic charge on the exposed areas of the layer, and the electrostatic latent image thereby obtained by applying a finely divided electrolytic material, commonly referred to as "toner". The toner is usually attracted to the areas of the layer which retain charge, thereby forming a toner image corresponding to the electrostatic latent image. This powder image can then be applied to a carrier surface, for example Paper, to be transferred. The transferred image can then be made permanent on the carrier surface by means of heat be fixed. Instead of uniform charging of the photoconductive layer and subsequent exposure of the layer to a light and shadow image, the latent Image also through direct charging of the layer in an image-like manner Configuration can be generated. The powder image can be on the photoconductive layer itself fixed v / ground, if, the PuI Verbildtransfersstufe should be omitted. The above-mentioned heat setting can also be carried out by other suitable ones Fixing processes, for example by treatment with a solvent or by applying a top coat, can be replaced »

There are already various methods of applying the known electroscopic toner particles on the latent electrostatic image to be developed. A development process is known as "cascade development" (see US Pat. No. 2,618,552). In this procedure a developer material made up of relatively large carrier particles consists of: electrostatically attracted fine

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Partial toner particles are encased, applied to the surface carrying the latent electrostatic image and The composition is rolled over or drizzled over it the carrier particle is selected so that the toner particles are triboelectric with the desired polarity being charged »When the mixture is allowed to trickle onto or over the latent image bearing surface is allowed to roll away, the toner particles are removed from the. charged areas of the latent image are electrostatically attracted and captured but not deposited on the uncharged or background areas of the image. Most the toner particles that are randomly deposited in the background districts are removed by the rolling carrier, since the electrostatic attraction between the toner and the carrier is greater than that between the toner and the carrier non-loaded background. The carrier and excess toner particles are then recycled. This technique works extremely well for developing line copy images.

Another method for developing latent electrostatic Images is the "magnetic brush method" described, for example, in U.S. Patent 2,843,063. With this one Process acts - a magnet as a carrier for the developer material, which consists of toner and magnetic carrier particles. The magnetic field of the magnet causes the magnetic carrier particles in a brush-like configuration relay a message. This "magnetic brush" is used with the latent electrostatic image · bearing surface brought into contact and the toner particles are as a result of the electrostatic Attraction pulled down by the magnetic brush onto the latent image «.

Another method of developing latent electrostatic Images is the so-called "powder cloud process"

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(powder cloud process), as for example in the US patent 2,221,776. In this process, a developer material that is made up of electrically charged There is toner particles in a gaseous fluid, past the surface carrying the latent electrostatic image. As a result of the electrostatic attraction, the toner particles are drawn down from the gas onto the latent image. This method is particularly suitable for developing continuously toned images. Other development processes, such as »the" touchdown "development as shown in the US Pat. No. 3,166,432 may be described in certain appropriate cases can also be used.

The toner particles are usually thermoplastic Resins selected to have melting points well above the. respective Ambient temperatures are that during the electrostatic Deposition (development) can occur, and in most cases it is caused by radiant heat on the image substrate fixed. Except as described in U.S. Patent 2,297,691 Developing powder or toner materials is already one A number of additional toner materials have been developed, particularly for use in the more recent development processes including the cascade development mentioned above. These new toner materials generally consist of several different materials improved resins mixed with different pigments, such as carbon black! see in this context, for example U.S. Patent 2,659,670 in which a toner resin from a phenol-formaldehyde, modified with rosin is, the US Re issue patent specification 25 136, in which a below Using a resin made from polymerized styrene electrostfitographic toner, and U.S. Patent 3 079 34-2, in which a plasticized mixed polymer resin is described in which the comonomers styrene and a methacrylate from the group butyl, isobutyl, ethyl, Are propyl and isopropyl.

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Heretofore, these toners have generally been prepared by thoroughly mixing a thermally softened resin and a coloring agent to form a uniform dispersion, for example, by mixing these raw materials in a rubber mill or the like, and then pulverizing this material after cooling to form small particles This comminution of the colored resin has heretofore been mostly accomplished by atomizing the material with a nozzle. Although this process can produce some excellent toners, it has certain disadvantages. For example, this results in a rather wide range of particle sizes in the toner parti No ₀ Although the average particle size is of the toner produced by this method is generally within the range between about 5 and about 10 microns, even single particles are often produced, whose size range from sub-micron to to more than 20 microns. In addition, these atomized toners usually contain some free black particles as a result of the breakdown by fine agglomerates. In addition, this toner manufacturing process has certain limitations on the material selected for the toner because the colored resin must be sufficiently brittle to be pulverized at an economically viable production rate. ”The problem that arises According to this requirement, ₉ then ₉ if the colored resin is sufficiently brittle for a really high rate of pulverization, it tends to have an even broader particle size range during pulverization. to form including a relatively large percentage of fines and when it is used so developing in electroratographic imaging devices is often subject to further pulverization. All other requirements placed on electrostatographic developers or toners, including the requirement that they must be storage-stable, non-agglomerating and have the correct triboelectric properties for development and

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need to have a low melting point for heat fusing are only exceeded by the additional requirements that must be met in this toner production process. Some developer materials, while "having certain desirable properties, such as suitable triboelectric properties, are unsuitable because they have a tendency to cake together, to form bridges and agglomerates during handling and storage. The tendency of the toner particles to form on the images The flow properties of many toners are adversely affected when the relative humidity is high. The triboelectric properties are adversely affected when the relative humidity is high or low Fourth, some toner particles with change in relative humidity and are therefore not suitable for use in electrostatographic imaging systems, particularly in automatic devices, in which toners with stable and voi ^: Ij, predictable triboelectric values are required suitable. Another factor affecting the stability of the triboelectric properties of the toner is that the toner particles can be compressed (toner impaction). When the toner particles are used in automatic devices and recycled through many cycles, the many collisions that occur between the toner particles result , the carrier particles and other surfaces occur in the device, to the fact that the toner particles are welded onto the surface of the carrier particles or otherwise pressed into the carrier particles. The gradual accumulation of toner material permanently fixed on the surface of the carrier particles leads to a change in the triboelectric value of the carrier particles and thus contributes directly to the deterioration of the copy quality through possible impairment (destruction) of the carrier's capacity to carry toner.

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particles to contribute «,

Other methods of making toners are known, for example, by spray drying a colored resin solution as described in US Pat. No. 2,357,809. Although small, well-shaped particles can be produced by this method, some particles tend to bleed out of the dye and to be unstable under the influence of light, heat and / or handling. Since! Toner VOr ₃ are exposed to many of these influences during or after the image generation, they are therefore not always suitable for all purposes «,

Another method for producing a toner is that a Hara dissolved in a solvent having a low melting point is spray-dried and then the spray-dried particles obtained are dissolved in a solution of a second, shell-forming resin ₉ in a solvent that is a ITicht-solvent is of the resin having the low melting point are dispersed ₈ ^ form of encapsulated toner particles as described in US Patent No. 3,338,991 "laughing this method, although encapsulated toners are produced, however, there is a Multi-step process that is time consuming and required multiple treatment processes and containers and the use of different solvents. In addition, a sticky core or liquid cannot be collected and the second solvent must not swell the core «

The difficult part of most encapsulation manufacturing is there in preventing agglomeration at some point in the process <> Agglomeration is one of the previously known spray drying encapsulation processes during storage or spraying of the iProclaier charge

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materials a major problem. Overcoming these problems there would be a wide scope in terms of the choice of materials, solvents, temperature range, etc. Material concentrations allow and the appropriate selection of conditions for most core and wall combinations enable., The difficulty or impossibility of manufacture is of very small microcapsules of a desired size with a relatively narrow size distribution also a major limitation of the previously known encapsulation methods. In addition, the manufacture of an encapsulated electrostatographic toner material, which under Application of pressure can be fixed, beneficial, as non-encapsulated materials, the so-called cold Cold flow tend to form sticky images on the copy sheet, which often appear on other neighboring ones Stain leaves (to be transferred). Toner particles, that contain non-encapsulated materials that are subject to cold flow tend to break down during manufacture and bridges during shipping in bins as well as within the electrostatographic imaging device to form, glue together and adhere to each other. Also, the toner material should be able to hold a charge of the Assume correct polarity, for example, in cascade, magnetic brush, or touchdown development systems is brought into contact with the surface of the carrier materials. Some toner materials that have many properties which are desirable in electrostatographic toners disperse poorly and can be used in automatic Copying and duplicating devices not used »Other toners distribute themselves well, but produce images that which are characterized by low density, poor resolution or a high background. Also ßind some toners are unsuitable for processes in which an electri, i; ostatograpbischG Transfer is applied.

In general, the term "phase

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separation "to understand the separation of a liquid phase or a solid phase from a liquid phase", A suitable form of liquid phase separation of aqueous media is known as coacervation and is described, for example, in US Patents 2,800,457 and 2,800,458 US Patent 2,800,458 described method comprises an undesirably large number of stages and _is} that (1) forming an emulsion with a gellable colloidal material (2) by adding an aqueous salt solution at a temperature above the melting point of the colloidal sol induces coacervation, (3) the colloid gels by pouring the coacervate mixture into a cool salt solution, (4) washing with water and filtering to remove the salt, (5) hardening the filter cake with an aqueous formaldehyde solution, (6) removing residual Formaldehyde 'washes with water and filtered and (7) adjusts the water concentration or the remaining liquid Liquid removed if desired. A further disadvantage is that it is extremely difficult to control the particle size distribution. Also, many microencapsulation processes are limited to producing particles that are about 40 microns and larger based on the average particle diameter. Earlier phase separation encapsulation processes in liquid media avoid this lower limit, but they have the same difficulties with regard to controlling the particle size and also with regard to the coordination of the conditions to prevent agglomeration

Spherical particles are desirable for many uses. Spray drying and some other encapsulation processes produce spherical particles «. Most of the other toner production process lead to irregular shaped particles as in the method in which the grinding or pulverizing an agglomerated mass is erforderliöh ₀ As

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the previously known encapsulation methods have one or more of these disadvantages there remains a need for an improved encapsulation method.

It is therefore an object of the present invention to provide an improved method for encapsulating a liquid, semi-solid or solid granular material in a shell material which does not have the disadvantages described above, is simple, effective and one-step and can be carried out continuously problems with agglomeration, caking, bridging and blocking of the particles do not arise. Another object of the invention is to provide a method for encapsulating a liquid, semisolid or solid core material in a sheath material, by means of which it is possible to very small microcapsules of a desired size and a gesteue ⁷ "th; prepare size distribution, stable electrostatic A further object of the invention is to provide a method of encapsulation of toner particles that have a low melting point and provide images with a high density, excellent resolution, low background and which do not experience distribution and compression problems in electrostatographic imaging systems.

It has now been found that these goals can be achieved with a method for Encapsulation of liquid, semi-solid and solid core materials in a shell material can be achieved in which a Single phase solution of the core and shell materials in a single one Stage sprayed or, atomized and spray-dried.

The invention relates to a method for encapsulating a

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liquid, semi-solid or solid core material in a shell material, which is characterized in that a single-phase solution of the core material and the shell material is produced and this solution is spray-dried _{or the like}

The invention is in particular a method for encapsulating the · substantially soluble portion of a core, which is characterized in the material is substantially soluble portion of a shell material of which solubility is different from the solubility of the notch material ₉ that

(a) the core material and the shell material in at least one relatively volatile solvent dissolves under, formation a solution,. ·

(b) produces small individual drops from the solution practically at the same time,

(c) at least some of the solvent is removed from the individual droplets by evaporation, thereby increasing the concentration of the dissolved core material and shell material increased and practically all of the core material, preferably in the form of a The solvent-poor phase is separated, and

(d) removing additional solvent from the individual droplets, causing the shell material to deposit around the core material with the formation of practically dry, "small", spherical ones Particles in which the core material is encased in the shape of a capsule by the shell material.

The inventive method consists in principle that one selects the starting materials including the solvent or the solvent mixture so that during the Drying by changing the concentration of the solvent or solvents and the dissolved materials and in some cases the reduction in the pH value or the temperature of the atomized solution results in a phase separation of the nucleus

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terials in the form of a low-solvent phase with a high Surface tension is caused in a solution of the shell material. The solution of the shell material then surrounds the core phase and encapsulates it and finally forms when the solvent evaporates from the particles in the air a practically dry, solid capsule shell, "In the separated core material phase and the separated shell material phase it can be a low-solvent phase or a non-solvent-free phase Act phases. The encapsulated product obtained in this way can be processed in any conventional or suitable manner and collected in a dry, free-flowing manner.

The desired core and wall materials can be selected first can be selected according to the desired capsule properties. Then the solvent or the solvent mixture can so selected to achieve the desired encapsulation. This selection is made on the basis of solubility of core and wall material and solvent volatility. Having selected the desired core and wall materials can be used to determine the general Solubility properties of the materials are carried out. Once these general characteristics have been established possible solvent combinations are selected and determined by determining the solvent ratios at the cloud point examined more closely. In the simple cases, the preliminary tests are sufficient to enable the selection of a suitable solvent system to allow. However, the procedure used for these simple cases is easiest to understand: if there is alo simplified version of the for more complicated cases applied method »is considered in which either the mutual solubility of the core and wall materials is limited or difficulties in finding the

»» ΤηTi 4 ™ pt τ · "Ϊ il * l Q

Conditions for the phase separation of the Kerry occur without simultaneous precipitation of the wall material. For more complicated ones

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Cases, a solubility range chart is used, In a diagranim with the solubility parameter and the hydrogen bonding parameter an area is drawn as coordinates that includes the solvents in which the Core and wall materials are soluble «, For simplicity, two-dimensional diagrams can be used, it should but also possible polarity effects "are taken into account. The solubility range is determined by titrating a Solution of the core and wall materials against a non-solvent, the cloud point being taken as the limit of the solubility range. Use is made of the fact made that both parameters for the mixture can be calculated by the following equation, which is only for the solubility parameter is indicated:

where mean: x. and6 * · the volume fraction and the solubility parameter of the solvent i and b _m the solubility parameter for the mixture.

If you consider the solubility ranges of the two wall and core materials is entered in the same diagram, then, provided that no interaction occurs, the Starting solution lie within the overlap area of the two surfaces. In addition, the solvent composition should be such that when the solvent mixture evaporates, the two parameters move in such a direction that leads to a point which is within the range of solubility of the wall material, but outside the solubility range of the core material. This point should can be achieved "while the solution of the wall material is still flowable enough to allow the formation of a united (uniform) Allow core phase if so desired. In practice, it should be assumed that there are no significant changes

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effect occurs between the core and wall materials, can be checked by looking at the cloud points of mixed solutions determined. The cloud point also changes to a certain extent with the core and wall material concentration and therefore concentration limits should be set.

Further features and advantages emerge from the following description in conjunction with FIGS. 1 and 2 of the enclosed Drawing. Mean:

Fig. 1 is an example of a solubility diagram of the above discussed Kind and

2 shows the schematic representation of the processes which take place when the method according to the invention is carried out.

In the solubility area diagram shown in Fig. 1 of the accompanying drawings, points are for some solvents used. The solvent selected for carrying out the method according to the invention as shown in FIG. 1 would be approximately correspond to point A and could be a 1/1 mixture (related on the volume) of methyl ethyl ketone and heptane. Further experiments would then have to be carried out to determine whether any significant change in solubilities due to any interaction between the core and wall materials occurs, and about the properties and composition of those formed on evaporation of the solvent To determine phases. With the proposed solvent ByStem and assuming no interactions, solvent evaporation would cause the.parameters from the point Ä along the dashed line in the direction of point D (pure heptane). At point B the phase separation of the core material would occur

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begin and after the further evaporation, a phase separation of the wall material would begin at point C and three phases (excluding any solid pigment etc. which may be present) arise, as shown in FIG. 2. Further removal of the solvent will lead to a complete phase separation of the wall material and a subsequent removal of the solvent phase by evaporation and finally a complete drying and hardening of the capsules ₀

Although there are only two materials in this example, the specified procedure can also be used for combinations of several Materials are applied. If there is more than one soluble core and wall material, the parameters for the Solvents should be within a range that all materials should overlap and all core materials begin with the phase separation in front of each of the wall materials. Further core materials could thus be used in the example shown with cloud points between points A and B and other wall materials with cloud points between 0 and D exist. All materials should be compatible with one another for a given phase, for example all core materials or a deposited core or wall can be formed.

In one embodiment, the encapsulated particles are made by selecting the components in an egg phase solution in which all of the substantially soluble portions of the core and shell materials are dissolved in a single solution agent system to allow the sequential phase separation of the core and shell materials during the drying process . In the Einphasenlösungsmittelsystem is made of the differences in solubility and the Pplymerisatinkompatibilität the various core and Hüllenraaterialies use ₅ ■

so that the core material is separated or excreted in a higher solvent concentration than is necessary for phase separation of the wall material when the solvent is removed. In this embodiment, the solvent system remains a mutual (common) solvent for the core and wall material during the drying and phase separation which is caused by the polymer incompatibility. For the purposes of the present invention, polymers are incompatible with one another if they are not miscible with one another in a common (reciprocal) solvent system. That is, when the concentration of the solvent system is reduced, one polymeric material separates out in the form of a phase before the other polymeric material. In this embodiment, the phase separation due to the polymer incompatibility, combined with a lower solubility, can also be used. In addition, the materials need not be polymers, but other core materials and film-forming shell materials can also be used. Furthermore, a single solvent can be used in this embodiment, but solvent mixtures can also be used, which can be used with advantage in certain core and wall materials. If a single solvent is used, the system should be such that partial removal of the solvent causes the core material to separate out preferably in the form of a phase and that further removal of the solvent causes the shell material to wrap around the core material Deposits forming a wall. When using several mutually miscible solvents in a system, the system should be such that the partial removal by evaporation of each solvent in the ratio in which they are removed causes a phase separation of the less soluble core material and further solvent removal ^: tion leads to the fact that the more soluble shell material '■■

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deposits around the core material to form a wall.

In another embodiment of the method according to the invention are the encapsulated particles produced by selection 4 © 3? Components in a single phase solution, in'der all essentially soluble parts of the core and shell materials are dissolved in a mixture of two solvents and in one of the two solvents is a non-solvent for the core material and by evaporation during can be sufficiently concentrated after drying to reduce the To effect phase separation of the core material before the deposition of the shell material. In this embodiment the solvent system during drying to a non-solvent for the core material, but remains a solvent for the wall material. This embodiment can also be viewed as a mutual (common) solvent / preferred solvent system and that includes each System in which the wall material remains in solution. In an example of this embodiment, in a solvent system, which consists of chloroform and isopropanol, the polymeric reaction products of isopropylidenediphenoxypropariol j and adipic acid as the core material and the reaction product]

j a dimer acid with a linear diamine (e.g. Emerez j

1540 from Emery Industries, Inc.) 'solved. I.

In a further preferred embodiment of the method according to the invention, the encapsulated particles are produced by selecting the components in a single-phase solution in which all essentially soluble parts of the core and V / andmaterials are dissolved in a mutual (common) solvent mixture and in which the solvent mixture during the drying first a 'non-solvent for the core material and later a Mcht-solvent for the wall material. This embodiment can be used as exchange-ι

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Lateral solvent / reciprocal non-solvent system and this includes any system in which three phases, the nucleation phase, the wall formation phase and the solvent phase, coexist during the final stages of drying. An example of this embodiment is a solvent system consisting of chloroform and heptane in which the polymeric reaction product of isopropylidenediphenoxypropanol and adipic acid as a potential core material and polystyrene as a potential shell material are dissolved. In the three above-mentioned embodiments, the solvent system in the starting solution initially represents a common (mutual) solvent for the core and wall materials _o If a solvent mixture is used, the change in the concentration of the more volatile solvent causes the core material to phase separate before deposition the wall material,

In another preferred embodiment of the process according to the invention, the encapsulated particles are produced by selecting the components in a single-phase solution in which the essentially soluble parts of the core and shell materials are dissolved in a solvent system in order to ensure the successive phase separation of the core and shell materials during the Allow drying to change the pH of the solution. For example, a single phase solution of the core and shell materials is prepared and then spray dried so that the relatively volatile solvent system is evaporated to form dry, finely divided, encapsulated particles. However, when water soluble materials are used and the core material is soluble only at a high pH, the volatilization and evaporation of an ammoniacal or alkaline solution of the core and wall materials results zn of ammonia or an other alkaline material by spray-drying

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a lower pH value, which results in a phase separation of the core material with a subsequent phase separation of the Wall material causes dry, finely divided, encapsulated particles to form

In another preferred embodiment of the invention according to the "method, the encapsulated particles are produced

such
provides through / selection of the components in a single-phase solution in which all essentially soluble parts of the core and shell materials are dissolved in a solvent system that the successive phase separation of the core and shell materials during drying by cooling the solution with or without vacuum during drying is possible. For example, the core material can be produced by phase separation by cooling during spray drying with or without vacuum, whereby the temperature of the droplets is lower than the initial temperature and is controlled by controlling the pressure and the temperature of the introduced air or another drying gas and the solvent vapor concentration.

If a single core product is desired, the Core materials and solvents are selected so that it is ensured that the core phase has a noticeably higher surface tension than the wall phase, the system should also be such that the nuclear void forms during the the residual solution carrying the wall phase is sufficiently flowable to move and coalesce the separated particles to allow the core phase that forms first *

Any suitable solvent system can be used in the process according to the invention are used, whereby it is mainly important to ensure that all essentially soluble parts of the core and shell materials are soluble in this solvent or in this solvent mixture and the evaporation properties

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Shafts of the solvent or the solvent mixture are such that they allow a successive phase separation of the core and shell materials during drying. Examples of suitable solvents are water, benzene, chlorobenzene, methanol, ethanol, propanol, isopropanol, butanol, chloroform, methyl ethyl ketone, ethyl acetate, heptane, hexane, cyclohexane, ethylene dichloride, methylene dichloride, tetrahydrofuran, acetone, dimethylformamide, dichloromethane, alkanes and those with an alkane Boiling point from about 0 to about 200 ^° C. In general, the appropriate amount of solvent and non-solvent materials for controlling subsequent phase separation can be easily determined by first considering the relative solubilities of the core and shell materials in the solvent system suitable temperatures determined. Suitable temperatures are those temperatures at which a solution of a suitable concentration of the core and shell materials in the solvent system can be obtained. Thus, by merely adjusting the solvent system concentration, many compositions are useful at room temperature.

Any suitable liquid, semi-solid or solid material which is soluble in the same solvent or in the same solvent mixture as the shell material can be used as the core material for the production of an encapsulated product by the process according to the invention. Examples of typical liquid core materials are water, oils, low molecular weight polymers such as polyester (e.g. Co-Rezyn 3 from Interplastic Corporation), polyester-based urethane polymers (e.g. Formrez P- ⁰ Z10 from Witco Chemical Corporation), epoxidized bisphenol A - ^ crylat (eg Epocryl U-12 from Shell Chemical Company), the reaction product of dimerized linoleic acid with diamines or polyamines (eg Versamid II5 and 140 from General

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Mills Chemical Division), polyamides (e.g. polyamides 315, 235 ■ and 34-0 from Union Carbide Corporation), polybutadiene (e.g. Poly B-D, a liquid polybutadiene resin with terminal Hydroxyl groups from Sinclair Petrochemicals Incorporated), silicone rubbers (e.g. W 981 from Union Carbide), mixed polyesters of phthalic acid and an alkyl dicarboxylic acid, condensed with an alkyl diol (e.g. "Santicizers 4-QJ? and 411 der Monsanto Chemical Company) and mixtures thereof. Examples of typical semi-solid core materials are polyester (e.g. Epon 872 from Shell Chemical Company), urethane polymers polyester-based (e.g. Formrez P-314, P-211 and MG-4 from the company Witco Chemical Corporation), epoxidized phenol-formaldehyde resins (e.g. epoxy-Wovolak ERLB-0449 from Union Carbide Corporation), polyisobutylene (e.g. Oppanol B-10 from Badische Anilin- und Soda-Fabrik), the reaction product of dimerized linoleic acid with, diamines or polyamines (a * B " Versamid 100 from General Mills Chemical Division) and Mixtures of these. Examples of typical solid core materials are polyurethane elastomers (e.g. Estane 5701, 5 702, 5 710 and 5 714 from B.F. Goodrich Company), polyester-based alkyd resins, Polyester-based urethane polymers (e.g. Formrez P-410, P-610 and L10-72 from Y / itco Chemical Corporation), Polyamides, such as the reaction products of dimerized linoleic acid with diamines, etc. Polyamines (e.g. Versamide 712, 948 and 950 from General Mills Chemical Division), the reaction products of dimeric acids with linear Diamines (e.g. Emerez 1530 »1538 and 1540 from Emery Industries Incorporated), ester resins such as rosin esters and modified rosin esters, polyvinyl acetate, the polymeric reaction product of isopropylidenediphenoxypropanol and adipic acid, the polymeric reaction product of isopropylidenediphenoxypropanol and sebacic acid, G ^ c-di-urea, polyacetaldehyde, Styrene / butadiene block copolymers (e.g. Kraton 4113 from Shell Chemical Company) and mixtures thereof «,

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As a shell material for the according to the method according to the invention encapsulated product, any suitable material can be used which is in the same solvent or in the same Mixed solvent as the core material is soluble. The shell material can be a homopolymer or a copolymer act of 2 or more monomers or a terpolymer. Examples of typical envelope materials are polystyrenes (e.g. PS-2, Styron 666 and 678 from Dow Chemical Company, Lustrex 99 from Monsanto Chemical Company) , Styrene / methacrylate copolymers and styrene / acrylate copolymers, Polycarbonates (e.g. Lexan 101, a poly (4,4'-dioxydiphenyl-2,2'-propane carbonate) General Electric Company), polyethers, low molecular weight polyethylene, Polyesters, such as polymeric acrylic and methacrylic acid esters, fumarate polyester resins (e.g. Atlac Bisphenol A from the company Atlas Chemical Company), Dione isopolyester resins made by the company Diamond Shamrock Chemical Company, crooked hair polyester resins (e.g. K-2200 and K-1979 from Lawter Chemicals, Incorporated), Polyamides such as a.B. the reaction product of terephthalic acid and an alkyl-substituted hexamethylenediamine (e.g. Trogamid T Dynamit Nobel 3aies Corporation), the Heaktionspro-. products of dimerized linoleic acid with diamines or polyamines (e.g. Versamid 712, 948 and 950 from General Mills Chemical Division), the reaction products of dimeric acids with linear diamines (e.g. Emerez 1530, 1538, 1540 and 1580 of the Emery Industries Incorporated), naturally occurring materials such as gelatin, corn, gum arabic and the like, as well as mixtures thereof.

Although for the preparation of electrostatographic toner materials are all well-known resin production materials electroscopic nature and form when coming out of the solution contiguous balls, can be used to produce the shell material solution, has been shown _t that electrically insulating, water-insoluble, thermoplastic or heat:

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hardening synthetic polymer resins in the thermoplastic stage form toners which have many highly desirable properties, particularly for use in automatic copying machines in which heat fusing is used to fix the toner image on the copy sheet. In the event that the finished toner is to be used in a process in which other toner image fixing processes are used, the resins can be modified accordingly. For example, when the toner image by melting by means of solvent vapor, as described in US Patent No. 2,716,907 describes or is fixed adhesive coating or by printing by applying the core and shell materials used need not necessarily be at relatively low temperatures softenable be. Since, as described in the introduction, the core and shell materials are first brought into solution in the process according to the invention, care must be taken that "those core and shell materials are selected which are mutually soluble in a solvent or in a solvent mixture and can therefore do so many thermoplastic or thermosetting resins can be used in the thermoplastic step. In the manufacture of electrostatographic toners, shell material resins containing a relatively high percentage of a styrenic resin provide images of good quality. The styrenic resin may be a homopolymer of styrene or of or act styrene homologues ί copolymers of styrene with other monomers containing a single, with a double bond to a carbon | exhibit atom-bonded methyl group Examples of typical monomeric materials being copolymerized with styrene by addition polymerization kö. Possible are p-chlorostyrene, vinyl naphthalene, ethylenically unsaturated monoolefins such as ethylene, propylene, butylene, isobutylene and the like, vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate, vinyl butyl chloride and the like, esters of aliphatic α-methyl en-mono -

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carboxylic acids, such as methyl acrylate, ethyl acrylate, n-butyl acrylate, Isobutyl acrylate, dodecyl acrylate, n-octyl acrylate, 2-chloroethyl acrylate, Phenyl acrylate, methyl-ot-chloroacrylate, methyl methacrylate, Ethyl methacrylate, butyl methacrylate and the like, acrylonitrile, Methacrylonitrile, acrylamide, vinyl ethers, such as vinyl methyl ether, vinyl isobutyl ether, vinyl ethyl ether and the like, vinyl ketones, such as vinyl methyl ketone, vinyl hexyl ketone, methyl isopropenyl ketone and dglo, vinylidene halides such as vinylidene chloride, vinylidene chlorofluoride and the like »and N-vinyl compounds, such as N-vinylpyrrole, !! - vinyl carbazole, N-vinylindole, N-vinylpyrrolidone and Like., · As well as mixtures thereof. The styrene resins can also be obtained by polymerizing mixtures of two or more of these unsaturated monomeric materials are made with a styrene monomer.

For an electrostatographic toner, the shell material of the encapsulated toner should have a blocking temperature of at least about 38 ^° C. If the encapsulated toner is characterized by a blocking temperature of less than about 38 C, the toner particles tend to agglomerate during storage and machine operation and they form undesirable films on the surface of reusable photoreceptors which adversely affect the quality of the image . It will be understood that the specific formulas given for the units contained in the shell material resins of the invention represent the vast majority of the units present but not the presence of. Exclude monomer units or reactants other than those specified. The ratio of core and shell materials to the solvent system can in general be any practical dilution. For example, the dissolved solids content of the solution can be about 0.5 to about 50.0% by weight, 1χ; 2θί »; · ^ν η ^ uf> ■.! ■>. e solution, it can vary, but it can also vary beyond that, whereby a general limitation is the phase

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separation of the core material and another the practical one Make availability of the concentration of the solute. The ratio of shell material to core material can be any have a suitable value and it generally varies with thickness, strength, porosity and solubility properties of the desired shell, in general, therefore, the ratio of shell material to core material should be between about 99 parts by weight of shell material to about 1 part by weight of core material to about 1 part by weight of shell material be about 99 parts by weight of core material. The preferred range is about 7 parts by weight ratio Shell material to about 1 part by weight of core material to about 1 part by weight of shell material to about 7 parts by weight of core material, when encapsulated particles with the best surface properties are to be obtained. In general The thickness of the shell material can be determined by the ratio of the amount of the core material to be encapsulated to the amount of the shell material being controlled. Therefore, if a thicker shell layer is desired, more shell material should be used because the ratio of shell material to core material remains constant during the method according to the invention. The size of the encapsulated particles also influences the shell thickness, since the shell thickness at a constant grain / The smaller the particles, the lower the shell ratio. is. '■

The solubilities of those which can be used in the process according to the invention Core and shell materials can vary considerably in a selected solvent system. So is for example a fully hydrolyzed styrene / maleic anhydride polymorizate soluble to about 2.0% by weight in water, but at least about 20.0% by weight in a 50/50 volume ratio soluble in methanol and water. The solutions of the desired grain and shell materials can be in proportion diluted or in concentrated form in water alone

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or by selecting a solvent or a mixture of solvents which depends on the relative solubilities of the materials used. aside from that The concentration of the core and shell materials can be increased by adding a solubilizing agent such as another hydrophilic liquid such as methanol or ethanol can be increased. . '

The core or shell material, or both the .. core and the shell material can be pigmented or colored or by adding a suitable pigment or a suitable one Dye or by adding both a pigment and a dye to the solution of the core and shell materials pigmented and colored. Through a suitable selection of the coloring agent and the solution system iait the desired surface, Interaction and solubility properties the pigment or the dye or the pigment and the dye in many cases in the core material or in the cladding material or at the interface between the core material and the shell material are concentrated. A dye is generally concentrated in the phase, core or wall, in which he is soluble. The solubilities obtained during encapsulation could potentially take the dye somewhere urge, but this would be a special case. For example, a dye that is soluble in the core material, which is insoluble in the shell material and soluble in the solvent phase, probably after phase separation of the wall be concentrated on the exterior of the capsules. In some cases, dyes form separate phases such as Pigment particles because of insufficient solubility in the core and wall materials, i.e. when the dye is removed of the solvent is soluble in the solution or only little or no solubility in the grain or Wall material has. In these cases, the solubility of the dye controls the

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however still flowable phases where the dye particles be concentrated in the dry capsule.

A pigment is generally concentrated in the granular or wall material which is preferentially adsorbed by the solution. With most carbon blacks, and probably with most pigments, the tendency to become adsorbed increases with increasing polarity and hydrogen bonding of the polymer. : The material that is deposited in the form of a low-solvent phase is also more easily absorbed. Therefore, in a system in which the polymeric reaction product of isopropylidenediphenoxypropanol and adipic acid is used as the core material and polystyrene as the wall material with carbon black as the colorant, all three factors favor the absorption of the polymeric reaction product of isopropylidenediphenoxypropanol and adipic acid, so that the carbon black becomes focused on the core phase. With polyisobutylene as the core material and poly (4-, 4'-dioxydiphenyl-2j2'-propane carbonate) as the wall material, the polyisobutylene has a low tendency to be adsorbed, not even by a low-solvent phase, and the soot remains in the Solution of the wall material to be deposited in the capsule wall ■ suspended. Surface active agents and Stability I lisa factors including such materials which} \ added for other reasons, such as _o Kernweichmacher-, f may alter the adsorption properties and therefore lead to DA i, that the pigment is concentrated in a different phase.

As the coloring agent for the encapsulated particles, any suitable pigment or dye or any suitable pigment and dye can be used. Electrostatographic Toner paints are known and include, for example Soot, uigrosine dye, aniline blue, calco oil blue, chrome yellow, Chrome green, ultramarine blue, cobalt blue, duPont-Oil .Red, Benzidine yellow, quinoline yellow, methylene blue chloride, phthalocyanine blue or green, halachite green oxalate, pine soot, Benrjal pink and

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Mixtures of these. The pigment or the dye or the pigment and the dye should be present in the toner in an amount sufficient to render it highly colored so that it provides a clearly visible image on a recording material. For example, if conventional xerographic copies are desired of typewritten documents, Toner, a black pigment such as carbon black or a black dye, such as ₀ to Amaplaöt black dye contained by National Aniline Products Incorporated. The pigment is preferably used in an amount of about 3 to about 20 weight percent based on the total weight of the colored toner, whereby better images are obtained. When the toner colorant used is a dye, significantly smaller amounts of colorant can be used.

When a pigment is used as the colorant for the toner particles, the process of the invention consists in that one an insoluble pigment is dispersed in a solution of the desired core and shell materials by vigorous stirring, then dries under controlled conditions so that some of the relatively volatile solvent is driven off is, and the core material preferably separates in the form of a phase with the formation of fine particles, and then further removing the solvent, thereby causing the shell material to be in the form of a phase around the core material, thereby forming the wall. In this process there is practically no free pigment formed because the pigment was found in the core or wall material or at the interface between the core and wall material v / can earth. The pigment need not necessarily be included in both the core and the wall of the particles to no, it can instead be included either in the core or in the V / and or in neither

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In addition, since the core material phase is desired to separate to form a continuous internal matrix, the pigment concentration is preferably low if the pigment is to form part of the core. Also, if the pigment is to form part of the shell, the concentration of pigment is preferably not so high as to prevent an impermeable shell from forming or otherwise adversely affecting the integrity of the shell, since the encapsulated toner particles generally have sizes within the range of If about 0.5 to about 35 microns is generated, the pigment should preferably be less than about 0.1 micron in diameter and, if possible, be smaller, as this not only benefits the uniformity of the final product color, but also a more stable suspension of the pigment is achieved before drying. In any event, the diameter of the pigment particles or other insoluble material should be about J5 volume% of the core diameter as the maximum for satisfactory encapsulation. There are simple relationships between particle diameter, core diameter and wall thickness. In particular, the wall thickness is directly proportional to the particle diameter ₀ If r the Yolumenverhältnis of core material to wall material as, the volume fraction of the

cw ⁷ ■

Core material as X _n , the capsule diameter and the core diameter

knife with d or -: - d, the total volume and the core volume with V or Y and the wall thickness with W, so the Wall thickness can be calculated as follows:

X _c = T ₀ A - (1 / 6Το _ο ² ) / (1 / 6τΓά ³ ) - d _o ³ / d ³

d = (X

Cu

\ i = (d - dJ / 2 = (d / 2) (1-- X _C ^V3 )

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For a volume ratio of core material to wall material from 1 to 1 is therefore W = (d / 2) (1-0.794), which corresponds to about 0.1 d. To achieve good effects in the production of Spray-dried toners, as further described in the examples below, become commercially available Carbon black pigments are used whose average particle size (in diameter) is within the range of about 200 millimicrons down to et v / a 20 millimicrons · By taking into account the solubility or the absorption, this can be Colorants are caused to deposit, as indicated above, in the core material or in the shell material.

By controlling the amount of core and shell materials in of the solution, the particle size and the amount of colorant in the solution or in the suspension and the size the droplets formed during drying and the size of the finished encapsulated particles formed after drying being controlled. For example, by changing the atomization speed the particle size changed without changing the solution concentration. This result is achieved because practically the amount of liquid solvent driven off by evaporation in each droplet of the same size is the same, as a result of which essentially an equal weight of core material and shell material remains with formation of the finished encapsulated particles.

In general, there are three methods of atomization used in the industry: atomization or spraying through nozzles under pressure, through two fluid nozzles and through centrifugal or spinning disks. For numerous uses in the Spray drying uses centrifugal disc atomizers which rarely clog and where erosion is seldom serious is and whereby, even if siG occurs, the operating characteristics are seldom affected ίίοίν atomizer can be changed and those under the Loaded under the action of gravity or under low pressure

'centrifugal disk atomizers)

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can be. Changes in particle size caused by the atomizer as a result of changes in the properties of the raw material or production speeds can usually be compensated for by changing the disk speed. The energy costs, especially compared to the two-fluid atomizers (two-fluid atomizers), are generally low. This atomization process, which is particularly suitable for slurries, slurries and highly viscous, thixotropic ¹ materials, is therefore used in many technical spray dryers such as are available for large-scale industrial processes. In general, the operation of the centrifugal disks depends on the introduction of a liquid or a semi-liquid into a rotating element, from which it is thrown out in the radial direction by the centrifugal force. The high velocity of the liquid leaving the rotor, including the fact that it flies apart (diverges), favors the disintegration of the liquid into small droplets.

Spray drying is the preferred working method with which it is possible to practice the one-step encapsulation process of the invention. Depending on the solvent used or the solvent mixture used, heating or cooling may or may not be required and for Encapsulation of core material within the wall material can any suitable atomization method can be used. For example, a single phase solution of the core and shell materials is made produced in which all essentially soluble parts of the core and shell materials are in solution, and this is then spray dried so that the relatively 'volatile solvent or the solvent mixture is volatilized and evaporated with the formation of dry, fine egg!) igen, encapsulated particles. As the core material preferably in the form of a phase from the spray-dried solution in each individual droplet separates with formation

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of the particle core, the shell material is then deposited around and encloses the core material.

In some instances where the shell material may tend to form separate, homogeneous, solid shell particles, this tendency can be reduced by changing the solvent system to change the ratio of surface tension and viscosities of the core material phase and the shell material phase in order to achieve a continuous., solution of the shell-forming material around the core material. In this manner, the encapsulation process of the present invention can produce large quantities of encapsulated material with an average particle size range of from about 0.5 "to about 1000 microns. The unit used for atomizing and drying is generally a spray dryer such as that used for example manufactured by Bowen Engineering Corporation of North Branch, New Jersey This unit is a laboratory conical dryer that uses air simultaneously and has a replaceable atomizing head located near the top the drying chamber is fixed and is fitted in the drying air distributor ring. the material used in the following examples most commonly atomizer is the ßektorenscheiben variant. This atomizer-type _t, as in this case, preferred when the liquid to be atomized a suspended Pi gment may be included, since other atomizing devices are often subject to erosion during atomization under high speed agitation with these solids.

Once the solution has been atomized to the correct droplet size, it moves through the drying air in the spray drying chamber until the solvent evaporates is aborted, with the core and shell materials

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• - 33 -

remain in the form of a single, spherically shaped particle, in which the core material is surrounded (encapsulated) by the shell material “This evaporation is caused by a high surface-to-mass ratio in the atomized droplets and the drying air speeds up 'The time' during which these droplets in suspension in the drying air being held is hereinafter referred to as "dwell time". Maintaining the right temperature the drying air is important for the effective operation of the system because the drying air is required to drive off the solvent or solvent mixture in each droplet by evaporation during the "hold time", while at the same time the particles must be cool enough when they leave the drying air chamber so as not to get to the Glue or agglomerate sides of the collection device in the collection device. It has been found that the most of the desirable encapsulated toner particles do this Result can be achieved by keeping the temperature of the drying air introduced at such a value which is just above the minimum value required to achieve evaporation of the solvent during the holding time (Residence time) is required. This result is obtained with polymer / solvent systems, because because of the evaporation of the solvent after the droplets are heated with the Air has come into first contact, the droplets tend to cool down so that they do not are more sticky when they leave the drying chamber, even if the initial temperature of the drying air is them would make you sticky. If one of the less volatile solvents is used, the droplets sometimes require a longer "hold time" or smaller droplets with a higher solids concentration can be used to achieve this result, so the solvents also at evaporate faster in the drying chamber at lower temperatures. With most common thermoplastic resins,

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those used in toners and those used for fusing by heat fusing or under pressure in electrostatographic Imaging processes are provided, the problem of excessive stickiness of the toner particles, which leave the drying chamber, thereby avoiding the fact that the existing air in polystyrene casings at a Maintains temperature of about 57 ° G (135 ° F) or below, depending on Calibration temperature of the resin. If for any reason a resin is used that is sticky at low temperatures is, for example, near room temperature, or when the "hold time" in the drying air chamber is so short that higher than average air inlet temperatures are required, it may be useful to quench the dried toner particles with a stream of cold air, if they leave the drying chamber in order to reduce their stickiness and their agglomeration and sticking in that Prevent Collectors »However, this level is unusual and not required for most common materials. That Material emerging from the spray dryer is collected in a cyclone collector, from which the completely dried particles can be withdrawn at the end of the process or continuously. It was also found that in the practical Implementation of the "method according to the invention vacuum or any method can be used with its Help it is possible to make a solution with or without the use of Ϋ / poor, depending on the volatility of the solvent system evaporate.

According to the method according to the invention, it is possible, by atomizing and drying a core and shell material containing solution without prior process steps the microencapsulation to achieve a core material in a shell material. This method can be used in a wide variety of ways Shell materials to a microencapsulation

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subject by choosing the right solvent or mixture of solvents. The method can be carried out with core materials, which are normally liquid, semi-liquid or solid and which can also consist of more than one substance, it also being possible for the shell material to contain more than one substance. The invention is particularly advantageous when the main core and shell materials have similar solubilities, for example when they are both hydrophobic and mutually (jointly) soluble in certain solvents. As explained above, the US Patent 3,338,991 is in the encapsulation according to the use of various solvents required, the use that is a solvent for the shell-forming resin which is a non-solvent for the core material _(. Also according to US In a microencapsulation according to the present invention, the core and shell materials are in a homogeneous solution until the solution is fine The present invention also relates to an improved method of encapsulating electrostatic / graphic developer materials which is much simpler u nd; provides electrostatographic toner particles with improved particle size uniformity. It has also been found that this method of manufacturing electrostatographic toners is capable of producing an encapsulated electrostatographic toner having an extremely small particle size. Both the evenness of the. Particle size as well as the fineness of the particle size, which can be achieved by the encapsulation process according to the invention, lead to toner encapsulated by this process

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- 36 -

with an extremely high resolution that can really be used in any electrostatographic process including those described above can. The ultimate resolution of an electrostatographic Namely, the imaging system is constrained by the largest toner particles in the area for development of the electrostatic latent image electrostatographic toner are included, regardless of the particular development method used »Even if now an optical system and an electrostatographic plate are able to provide latent electrostatic images with an extremely high resolution, so will the resolution of the Overall system deteriorates when the latent image is developed with an electrostatographic toner, the particles with a size substantially larger than the dimensions of any part of the latent image. It was found that the toner material obtained by these processes had a uniform spherical shape with a greatly improved Has development ability, especially in cascade systems, in which the developer uses the Plate rolls. Accordingly, the encapsulation method of the present invention is in many respects similar to the other methods Production of electrostatographic toners with a high resolution superior »With it it is possible to encapsulate Manufacture toner in a single step in a simple, economical, and effective manner with the same results as in a common time consuming multi-step encapsulation process receives. With the method according to the invention it is possible to use the previously known encapsulation methods to avoid own agglomeration problems. This also removes the limitations associated with manufacturing consist of toner particles by pulverization particle formation processes. With its help it is possible to create a electrostatographic toner with an extremely small particle size to manufacture. In addition, the particle

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the size range of the toner formed is considerably narrowed, so that the probability is greatly reduced or completely eliminates the fact that any particles are much larger than the average size as shown in an electrostatic graphic produced by a conventional method Toner may be contained * In addition, according to the invention it is possible to use an electrostatographic To manufacture toner that contains a liquid or sticky material that is not normally present in conventional homogeneous toner particles can be used.

The encapsulation method of the present invention is applicable to any System applicable in which the core and shell materials can be deposited sequentially in the form of a phase, and it is also applicable to any microencapsulation of the small particles are desired, such as, for example obtained by spray drying. The average size and size distribution of the microcapsules can be by Changing atomization and drying conditions in the same way and over the same size range varies are like atomizing and drying a solution with a single solute. In addition, it is according to the invention Process possible to encapsulate particles with different shell materials, e.g. a hydrophobic, lipophilic or lipophobic in nature. The inventive Process is particularly advantageous for the manufacture of a solid, coated toner material which is disclosed in is in an extremely fine state, for example consists of particles from about 0.5 "to about 35 microns in diameter. The particular particle size is for the The method according to the invention is not critical, but it is determined by the use for which the coated particle is intended. So, for example, is a finely ground one Powder or a finely dispersed liquid having particles on the order of about 0.5 to about 10 microns

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desirable for vitaraine and other nutritional supplements, for Substances to be incorporated into cosmetic preparations and for insecticides. A powdery material having a particle size of up to about 200 microns is desirable for rodenticides.

The encapsulated products of the invention can be used in compositions due to their unique properties can be used in a wide variety of Αηγ / endings. on In the cosmetic field, products such as soap bars, lotions and creams can be formulated to encapsulate, v / ater contain soluble ingredients that are in non-encapsulated form in the form of the other ingredients of the respective preparation would be unstable or incompatible. Because certain antibacterial agents, such as chlorinated phenols and neomycin sulfate, after prolonged contact with the soap are incompatible, it is possible by the present invention, for example, to produce a soap bar that contains these two ingredients.

In the field of landv,:. I ^ tschaft, encapsulated with advantage Nutritional supplements and medicines are made. For example, water-soluble fertilizers, e.g. Ammonium nitrate, urea and superphosphate, for fertilization of the soil can be encapsulated if a slow release of the fertilizer or a longer duration of action is desired is, for example, when a rapid release would "burn" the vegetation. To control pests Encapsulated insecticides can be applied to vegetation or incorporated into the soil without this the vegetation is damaged; moreover, the insecticide is not dissolved by moisture or rain and washed away so that the insecticide remains where it was applied until it is removed from the insect »Antihelminthics such as piporazine phosphate are included

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Or citrate and MethyIrοsanilinechlorid, can be encapsulated in Form incorporated into the putter of pets, with the encapsulated anthelmintics in the feed tasteless and are protected against decomposition even during storage in the feed. Rodenticides, e.g. Calcium cyanide, thallium sulfate and sodium fluoroacetate, the are unstable in the presence of moisture or have an offensive odor or taste to the rodents can also be encapsulated with advantage.

■ '. ι

Vitamins, minerals, amino acids and other Nährmittelzusätze can incorporated into the animal feed and even overall during storage to degradation under adverse conditions, such as _o air FeuchtigkeLt ^ and incompatible ingredients in the feed composition are protected in an encapsulated form. Similarly, nutritional additives can be incorporated into compositions for human consumption. .

The present invention can be used for medical treatment be used by both animals and humans. According to the method of the invention, drugs can be encapsulated v / ground, so that after ingestion they are released over a longer period of time, resulting in sustained therapeutic effect. To relieve the problem of stomach irritation or nausea caused by medication, such as emetine hydrochloride, quinacrine hydrochloride and p-aminosalicylic acid, coatings that do not dissolve in the stomach. Medicines such as penicillin can also be used accordingly and certain glandular extracts that are produced under acidic conditions or enzymes such as those found in the stomach are inactivated, advantageously encapsulated.

The following examples illustrate various methods of

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Manufacture of the encapsulated materials of the invention are intended to explain the invention in more detail without, however, limiting it thereto. The ones specified therein Unless otherwise stated, parts and percentages relate to weight. The examples where there is if it is not a matter of comparative examples, the various preferred embodiments of the invention are intended Explain the procedure.

The term "stick point" used in the following examples indicates the temperature at which a material adheres to a metallic substrate; for example, a continuous line of the sample is equilibrated on a hot Kofler pad for about 12 hours and then gently brushed away. The "sticking point" is the lowest temperature at which the sample sticks to the metallic plate of the hot Kofler block will. The blocking temperature is determined as the lowest temperature to which the toner has been exposed for an equilibration period, and at which the "crusty" mass formed can no longer be easily broken down into the original particles. The term "geometric standard deviation" is the deviation that occurs in determining the particle size and which is measured by the ratio between the particle diameter, which applies to 84% of the - ^ robe, and the particle diameter of at least 50 % of the sample.

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In a mixture of chloroform and heptane (with a volume ratio of 1: 1.3 chloroform / heptane) a solution of about 90 g of a polystyrene and about 180 g of the reaction product of isopropylidenediphenoxypropanol and adipic acids - with an average molecular weight of 4400 was prepared. Carbon black was dispersed in the solution by vigorous stirring. The final concentrations were about 1.5 percent of polystyrene, about 3.0 percent of the reaction product of isopropylidenediphenoxypropanol and adipic acid, about 0.5 percent of carbon black, and about 95.0 percent of solvent. The dispersed carbon black solution was prepared using a laboratory spray dryer from Bowen Engineering Incorporated, 76.2 cm (30 inches) in diameter, with a spinning disk atomizer operating at about 30,000 rpm and a feed speed of about 100 ml / minute was operated, spray-dried, the inlet temperature of the drying ^{air was about 43 ° C (HO 0} P) and the outlet temperature of the air was about 35 ° C (95 ⁰ P). The dry product was

volume- .

a powder with an average particle diameter of about 10.6 microns with a geometric standard deviation of about 1.51. The electron microscopic examination of the embedded Particle showed that the individual particles were mainly spherical and had a pigmented core was surrounded by a clear shell '. The glue dot, the blocking tests and scanning electron microscope examination of the crushed particles revealed that the shell was Polystyrene and the core was mainly the reaction product of isopropylidenediphenoxypropanol and adipic acid.

B e i s ρ i e 1 2

In a mixture of cyclphexane and ethylene dichloride (volume ratio Cyclohexane / ethylene dichloride = 2.2: 1.0) became a Solution of about 94.9 g of a polystyrene and about 142.3 g of des Reaction product of isopropylidenediphenoxypropanol and sebacin

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acid with an average molecular weight of 5650, soot was dispersed in the solution by vigorous stirring. The final concentrations were approximately 1.5 percent polystyrene, about 2.0 percent of the reaction product of isopropylidenediphenoxypropanol and sebacic acid, about 0.2 percent carbon black and about 96, ¹ J per cent of solvent. The solution with the carbon black dispersed therein was prepared using a laboratory spray dryer from Bowen Engineering, Incorporated, 76.2 cm (30 inches) in diameter and with a sector disk atomizer operating at about 50 rpm and a feed speed of about 200 ml / minute was operated, spray-dried. The inlet temperature of the drying air was about 57 ° C (135 ° F) »the outlet temperature of the air was about kl ° C (105 ° F). The dry product was a powder with a volume average particle diameter of about 7.9 microns and a geometric standard deviation of about 1.75. Electron microscopic examination showed that the individual particles were primarily spherical and had a pigmented core had, which was surrounded by a clear shell. The sticking point, the blocking tests and the examination of the crushed particles with the scanning electron microscope showed that the polystyrene shell and the core consisted mainly of the reaction product of isopropylidenediphenoxypropanol and sebacic acid.

Example 3

In a mixture of chloroform and heptane (chloroform / heptane volume ratio = 1: 1.3), a solution of about 8716 g of a polystyrene and about 8716 g of the reaction product of isopropylidenediphenoxypropanol and adipic acid. Under With vigorous stirring, carbon black was dispersed in the solution. The final concentrations were about 4.8 percent of polystyrene, approx 4.8 percent of the reaction product of isopropylidenediphenoxypropanol and adipic acid, about 0.5 percent carbon black and about 89.9 percent solvent. The solution with the dispersed carbon black was in

8/0601

a spray dryer from Bowen Engineering, Incorporated, 1.5 m (5 feet) in diameter with a sector disk atomizer, that at about 21,000 rpm and one. Feed rate of about 530 ml / minute, spray dried. The inlet temperature of the drying air was about 57 ° C (135 ° F) and the outlet temperature of the air was about 52 ° C (125 ° F). The dry product was a powder with a volume average particle diameter of about 14.7 microns and a geometric standard deviation of '" about 1.52. The electron microscopic examination showed that the individual particles were primarily spherical and had a pigmented core, which was surrounded by a clear shell. The glue dot, the blocking tests and the examination of the crushed particles with the scanning electron microscope showed that the polystyrene shell and the core were mainly consisted of the reaction product of isopropylidenediphenoxypropanol and adipic acid. -

Example 4

In a mixture of chloroform and heptane (volume ratio of chloroform / heptane = 1: 1.3), a solution of about 431 g of a polystyrene having about ¹ 131 g of the reaction product of isopropylidenediphenoxypropanol and adipic acid having an average molecular weight of from 856O prepared. Soot was dispersed in the solution with vigorous stirring. The final concentrations were about 4.8 percent of polystyrene, about 4.8 percent of the reaction product of isopropylidenediphenoxypropanol and adipic acid, about 0.5 percent of carbon black, and about 89.9 percent of solvent. The dispersed carbon black solution was prepared using a laboratory spray dryer from Bowen Engineering, Incorporated, 76.2 cm (30 inches) in diameter with a sector disk atomizer operating at about 50,000 rpm and a feed rate of about 200 ml / minute was operated, spray-dried. The inlet temperature of the drying air was about

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69.5 C (157 F) and the outlet temperature of the air was about 56.5 ° C (13 ¹ ^ ⁰ F). The dry product was a powder with a volume average particle diameter of about 1 *}. 1 micron and a geometric standard deviation of about 1.56. Electron microscopic examination showed that the individual particles were primarily spherical and had a pigmented core surrounded by a clear shell. The sticking point, the blocking tests and the examination of the crushed particles with the scanning electron microscope showed that the polystyrene shell and the core consisted mainly of the reaction product of isopropylidenediphenoxypropanol and adipic acid.

Example 5

A solution of about 2156 g of a polystyrene and about 2156 g of the reaction product of isopropylidenediphenoxypropanol and adipic acid with an average molecular weight of 4200 was prepared in a mixture of chloroform and heptane (volume ratio chloroform / heptane = 1: 1.3). With vigorous stirring, carbon black was dispersed in the solution. The final concentrations were about 4.8 percent of polystyrene, about 4.8 percent of the reaction product of isopropylidenediphenoxypropanol and adipic acid, about 0.5 percent of carbon black, and about 89.9 percent of solvent. The solution with the carbon black dispersed therein was prepared using a laboratory spray dryer from Bowen Engineering, Incorporated, 76.2 cm (30 inches) in diameter and a sector disk atomizer (spinning disk atomizer) operating at about 50,000 rpm and a feed speed of about 200 ml / minute was operated, spray-dried. The inlet temperature of the drying air was about 63 ⁰ C (145 ⁰ F) and the outlet temperature of the air was approximately 46 ° C (115 ⁰ F). The dry product was a powder with a volume average particle diameter of about 12.9 microns and a geometric standard deviation of about 1.53. the

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electron microscopic examination showed that the individual Particles were primarily spherical with a pigmented core surrounded by a clear shell. Of the Glue dot that showed blocking tests and examination of the crushed particles with the scanning electron microscope, that the shell made of polystyrene and the core mainly made of the reaction product of isopropylidenediphenoxypropanol and adipic acid passed.

Example 6

A solution in chloroform of about 400 g of a polystyrene and about 400 g of the reaction product of isopropylidenediphenoxypropanol and adipic acid having an average molecular weight of 614O was prepared. Carbon black was dispersed in the solution with vigorous stirring. The final concentrations were about 3.4 percent of polystyrene, 3.4 percent of the reaction product of isopropylidenediphenoxypropanol and adipic acid, about 0.4 percent of carbon black, and about 92.8 percent of solvent. The solution with the carbon black dispersed therein was prepared using a laboratory spray dryer from Bowen Engineering, Incorporated, 76 * 2 cm (30 inches) in diameter and a sector disk atomizer operating at about 50,000 rpm and a feed rate of about 200 ml / Minute was operated, spray-dried. The inlet temperature of the drying air was about 116 ⁰ C (240 ⁰ P), the outlet temperature of the air 'was about 82 ° C (l80 ° P). The dry product was a powder with a volume average particle diameter of about 12.9 microns and a geometric standard deviation of about 1.65. The electron microscopic examination showed that the individual particles were mainly spherical and had a pigmented core which was surrounded by a clear shell. The sticking point, the blocking tests and the examination of the crushed particles with the scanning electron microscope showed that the polystyrene shell and the core were mainly.

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consisted of the reaction product of isopropylidenediphenoxypropanol and adipic acid.

Example 7 ; ^: · '■''■■■

In a mixture of methylene chloride and acetone (methylene chloride: acetone = 1: 1) was a solution of about M42.5 g of a polystyrene and about 1 ^ 7.5 g of polybutadiene with terminal hydroxyl groups (e.g. Poly BD from Sinclaur Petrochemicals, Incorporated) manufactured. With vigorous stirring, carbon black was dispersed in the solution. The final concentrations were about 3/4 percent of polystyrene, about 1.1 percent of hydroxy-terminated polybutadiene, about 0.5 percent of carbon black, and about 95.0 percent of solvent. The solution with the carbon black dispersed therein was prepared using a spray dryer from Bowen Engineering, Incorporated, 1.5 m (5 feet) in diameter with a sector disk atomizer operating at about 21,000 rpm and at a feed rate of about 200 ml / minute was operated, spray-dried. The inlet temperature of the drying air was about 63.5 ° C ^(J l l6 ° F) and the outlet temperature of the air was about 52 ⁰ C (126 ⁰ F). The dry product was a powder with a volume average particle diameter of about 15 * 5 microns and a geometric standard deviation of about 1.60. The electron microscopic examination of the individual particles showed that they were primarily spherical and had a core that was surrounded by a pigmented shell. The sticking point, the blocking tests and the examination of crushed particles with the scanning electron microscope showed that the shell of polystyrene and the core consisted mainly of the polybutadiene with terminal hydroxyl groups.

Example 8

In a mixture of chloroform and isopropyl alcohol (volume ratio Chloroform: isopropyl alcohol = 1: 2) became a solution

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of about 200 g of the reaction product of a dine acid with a linear diamine (Emerez 1540 from Emery Industries, Incorporated) and about 200 g of the reaction product of isopropylidenediphenoxypropanol and adipic acid with an average molecular weight of 4400. With vigorous stirring, carbon black was dispersed in the solution. The final concentrations were about 4.8 percent of the reaction product of the dimer acid with the linear diamine, about 4.8 percent of the reaction product of isopropylidenediphenoxypropanol and adipic acid, and about 0.1 percent of carbon black, and about 90.9 percent of the solvent. The solution with the carbon black dispersed therein was prepared using a laboratory spray dryer from Bowen Engineering, Incorporated, 76.2 cm (30 inches) in diameter and a sector disk atomizer. operated at about 50,000 rpm and a feed rate of about 200 ml / minute, spray dried. The inlet temperature of the drying air was about 66.5 ° C (151 ° F) and the outlet temperature of the air was about 48 ⁰ C '(LL8 ° F). The dry product was a powder with a volume average particle diameter of about 11.6 microns and a geometric standard deviation of about 1.56. Electron microscopic examination showed that the "individual particles were mainly spherical in shape and had a core surrounded by a shell, both the core and the shell containing pigment. The sticking point, the blocking tests and the Examination of crushed particles with the scanning electron microscope showed that the shell consisted of the reaction product of dimeric acid with a linear diamine and the core consisted mainly of the reaction product of isopropylidenediphenoxypropanol and adipic acid.

Example 9

In a mixture of cyclohexane and ethylene dichloride (cyclohexane: Ethylene dichloride = 2.2: 1.0) became a solution of about 118.7 g of a polystyrene and about 118.7 grams of the reaction product of

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Ml

Isopropylidenediphenoxypropanol and sebacic acid with an average molecular weight of 5650. Carbon black was dispersed in the solution with vigorous stirring. The final concentrations were about 1.5 percent of polystyrene, about 1.5 percent of the reaction product of isopropylidenedephenoxypropanol and sebacic acid, about 0.3 percent of carbon black, and about 96.7 percent of solvent. The solution with the carbon black dispersed therein was prepared using a spray dryer from Bowen Engineering, Incorporated, having a diameter of 1.5 m (5 feet) with a sector disk atomizer operating at about 50,000 rpm and at a feed rate of about 200 ml / Minute was operated, spray-dried. The inlet temperature of the drying air was about 58 ⁰ C (137 ° F) and the outlet temperature of the air was about 43 ⁰ C (HO ⁰ F). The dry product was a powder with a volume average particle diameter of about 11.0 microns and a geometric standard deviation of about 1.82. The electron microscopic examination showed that the individual particles were mainly spherical and had a pigmented core which was surrounded ^{by a clear shell 1.} The sticking point, the blocking tests and the examination of the crushed particles with the scanning electron microscope showed that the polystyrene shell and the core consisted mainly of the reaction product of isopropylidenedphenoxypropanol and sebacic acid.

Example 10

In a mixture of tetrahydrofuran and benzene (volume ratio Tetrahydrofuran: Benzene = 2: 1) became a solution of about 10.0 g of a polystyrene and about 20.0 g of a polyurethane elastomer (Estane 5701 from B.F. Goodrich). The final concentrations was about 0.3 percent of the polystyrene, about 0.7 percent of the polyurethane elastomer, and about 99 percent 'of solvents. The solution was made using a laboratory spray dryer 12 inches in diameter with a spinning disc atomizer running at about 37,000 rpm and

* 309828/0681

operated at a feed rate of about 55 ml / minute, spray dried. The temperature of the drying air was about 25 ⁰ C (77 ° P). The dry product was a powder with a volume average particle diameter of about 12.0 microns. The electron microscopic examination showed that the individual particles were mainly spherical and had a core which was surrounded by a shell. The sticky point, the blocking tests and the examination of crushed particles with an optical and a scanning electron microscope showed that the shell was made of polystyrene and the core was mainly made of the polyurethane elastomer.

Example 11

A solution of about 1.5.0 g of a polystyrene and about 15.0 g of a polyurethane elastomer (Estane 5710 from BF Goodrich) was prepared in a mixture of tetrahydrofuran and benzene (volume ratio tetrahydrofuran: benzene = 2: 1). The final concentrations were about 0.5 percent of the polystyrene, about 0.5 percent of the polyurethane elastomer, and about 2.0 percent of the solvent. The solution was spray dried using a 12 inch diameter laboratory spray dryer with a spinneret operating at about 33,000 rpm and a feed rate of about 33 ml / minute. The inlet temperature of the drying air was about ¹ IO ⁰ C (104 ° F). The dry product was a powder with a volume average particle diameter of about 13.0 microns. The electron microscopic examination showed that the individual particles were mainly spherical and had a core which was surrounded by a shell. The sticky point, the blocking tests and the examination of crushed particles with an optical and a scanning electron microscope showed that the "shell was made of polystyrene and the core was mainly made of the polyurethane elastomer.

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Example 12

A solution of about 10.0 g of a polystyrene and about 20.0 g of a polyurethane elastomer (Estane 5710 from BP Goodrich) was prepared in a mixture of tetrahydrofuran and benzene (volume ratio tetrahydrofuran: benzene = 2: 1). The final concentrations were about 0.7 percent of the polystyrene, about 1.3 percent of the polyurethane elastomer, and about 98.0 percent of the solvent. The solution was spray dried using a 12 inch diameter laboratory spray dryer and a spinneret operating at about 2,000 rpm and a feed rate of about 37 ml / minute. The temperature of the drying air was about 40 ⁰ C (1OJj ⁰ F). The dry product was a powder with a volume average particle diameter of about 18.0 microns. The electron microscopic examination showed that the individual particles were mainly spherical and had a core which was surrounded by a shell. The sticking point, the blocking tests and the examination of crushed particles with an optical and a scanning electron microscope showed that the polystyrene shell and the core consisted mainly of the polyurethane elastomer.

Example 13

In a mixture of tetrahydrofuran and benzene (volume ratio Tetrahydrofuran: Benzene = 2: 1) became a solution of about 5.0 g of a styrene / n-butyl methacrylate copolymer (approx. 65/35 Percent by weight) and about 10.0 g of a polyurethane elastomer (Estane 5701 from B.F. Goodrich). The final concentrations were about 0.3 percent of styrene / n-butyl methacrylate copolymer, about 0.7 percent of the polyurethane elastomer and about 99.0 percent of the solvent. The solution was taking Using a laboratory spray dryer 30.5 cm (12 inches) in diameter with a spinning disc atomizer capable of

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was operated at about 2 * 1,000 rpm and a feed rate of about 35 ml / minute, spray-dried. The temperature of the drying air was about 30 ⁰ C (86 ° P). The dry product was a powder with a volume average particle diameter of about 11.0 microns. The electron microscopic examination showed that the individual particles were mainly spherical and had a core which was surrounded by a shell. D. The adhesive point, the blocking tests and the examination of crushed particles with an optical and a scanning electron microscope showed that the shell consisted of the styrene / n-butyl methacrylate copolymer and the core consisted mainly of the polyurethane elastomer.

Example 14

In tetrahydrofuran, a solution of about 1.1 g of a styrene / n-Butylmethaerylat-copolymer (about-65/35 weight percent) and about 10.0 g of a polyurethane elastomer (571 ¹ I Estane from BF Goodrich) were prepared. The final concentrations were about 0.2 percent of the styrene / n-butyl methacrylate copolymer, about 1.8 percent of the polyurethane elastomer, and about 98.0 percent of solvent. The solution was spray dried using a 12 inch diameter laboratory spray dryer and a spinning disc atomizer operating at about 33,000 rpm. The inlet temperature of the drying air was about 25 ° C (77 ° F). The dry product was a powder with a volume average particle diameter of about 9 * 0 microns. The electron microscopic examination showed that the individual particles were mainly spherical and had a core which was surrounded by a shell. The sticking point, the blocking tests and the examination of crushed particles with an optical and a scanning electron microscope showed that the shell consisted of the styrofoam / n-butyl methacrylate copolymer and the core consisted mainly of the polyurethane elastomer.

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Example 15

A solution of about 1.0 g of a styrene / n-butyl methacrylate copolymer (about 65/35 percent by weight) and about 3/4 g of a polyurethane elastomer ( Estane 571 ^ from BF Goodrich). The final concentrations were about 0.2 percent of the styrene / n-butyl methacrylate copolymer, about 0.8 percent of the polyurethane elastomer and about 99-0 percent of the solvent. The solution was spray dried using a 12 inch diameter laboratory spray dryer with a spinning disc atomizer operating at about 33,000 rpm. The inlet temperature of the drying air was about 25 ⁰ C (77 ° F). The dry product was a powder with a volume average particle diameter of about 8.0 microns. The electron microscopic examination showed that the individual particles were mainly spherical and had a core which was surrounded by a shell. The sticking point, the blocking tests and the examination of crushed particles with an optical and a scanning electron microscope showed that the shell consisted of the styrene / n-butyl methacrylate copolymer and the core consisted mainly of the polyurethane elastomer.

Example l6

In a mixture of tetrahydrofuran and benzene (volume ratio tetrahydrofuran: benzene = 3: 1), a solution of about 2.5 g of a styrene / n-butyl methacrylate copolymer (about 65/35 percent by weight) and about 5.0 g of a Polyurethane elastomers (Estane 5702 from BF Goodrich) produced. The final concentrations were about 0.3 percent of the styrene / n-butyl methacrylate x ¹ copolymer, about 0.7 percent of the polyurethane elastomer, and about 99 »0 percent of solvent. The solution was taking

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·. - 93 τ

Use of a laboratory spray dryer with a diameter of 12 inches (30.5 cm) with a pneumatic * atomizer operating at about 40,000 rpm, spray dried. The inlet temperature the drying air was about 25 ° C (77 ° F). The dry product was a powder with a volume average particle diameter of about 3.0 microns. The electron microscopic examination showed that the individual Particles were mainly spherical with a core surrounded by a shell. The glue point that Blocking tests and examination of crushed particles with an optical and a scanning electron microscope showed that the shell made of the styrene / n-butyl methacrylate copolymer and the core consisted mainly of the polyurethane elastomer.

Example 17

In a mixture of chloroform and tetrahydrofuran (volume ratio of chloroform: tetrahydrofuran = 20: 1), a solution of about 5.0 g of poly (4.4 ^l -dioxyphenyl-2.2 ^t -propane carbonate) (Lexän der GE Company) and about 5.0 g of a polyurethane elastomer (Estane 5701 from BF Goodrich). The final concentrations were about 0.5 percent of the poly (4,4'-dioxyphenyl-2,2'-propane carbonate), about 0.5 percent of the polyorethane elastomer, and about 99.0 percent of the solvent. The solution was spray dried using a 12 inch diameter laboratory spray dryer with a spinning disc atomizer operating at about 33,000 rpm. The inlet temperature of the drying air was about 21 ° C (7O ⁰ F). The dry product was a powder with a volume average particle diameter of about 11.0 microns. The electron microscopic examination showed that the individual particles were mainly spherical and had a core which was surrounded by a shell. The sticky point, blocking tests and examination of crushed particles with an optical and a scanning electron microscope showed that the

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Shell made of the poly (Ji, ¹ ! '- dioxyphenyl-2,2'-propane carbonate), and the core consisted mainly of the polyurethane elastomer.

Example 18

In a mixture of chloroform and tetrahydrofuran (volume ratio chloroform: tetrahydrofuran = 2: 1) a solution of about 3.0 g of a poly ( ¹ J ₁ ¹ J'-dioxyphenyl-2,2'-propane carbonate), (Lexan 101 from GE Company) and about 10.0 g of a polyurethane elastomer (Estane 5701 from BF Goodrich). The final concentrations were about 0.5 percent of the poly ( ¹ L, V-dioxyphenyl-2,2'-propane carbonate), about 1.5 percent of the polyurethane elastomer, and about 98-0 percent of the solvent. The solution was spray dried using a 12 inch diameter laboratory spray dryer with a spinning disc atomizer operating at about 33,000 rpm. The inlet temperature of the drying air was about 21 C (70 ⁰ F). The dry product was a powder with a volume average particle diameter of about 12.0 microns. The electron microscopic examination showed that the individual particles were mainly spherical and had a core which was surrounded by a shell. The glue point, the blocking tests and examination of crushed particles with an optical and a scanning electron microscope showed that the shell of poly (i |, ¹ J '-dioxyphenyl-2,2' propane carbonate) and the core mainly composed of the Polyurethane elastomers passed.

Example 19

In a mixture of tetrahydrofuran and benzene (volume ratio Tetrahydrofuran: Benzene = 2: 1) became a solution of about 3.5 g of a polystyrene, 5 g of a polyurethane elastomer (Estane 5701 from B.F. Goodrich) and about 1.5 g of a polyester (Epon 872 from Shell Chemical Company). The final concentrate

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The ions were about 1.7 percent of the polystyrene, about 2.5 percent of the polyurethane elastomer, about 0.8 percent of the polyester, and about 95.0 percent of the solvent. The solution was spray dried using a 12 inch diameter laboratory spray dryer with a spinach sprayer operating at about 24,000 rpm and a feed rate of about 15 ml / minute. The temperature of the drying air was about 35> 6 ° C (96 ⁰ P). The dry product was a powder with a volume average particle diameter of about 10.0 microns. Electron microscopic examination showed that the one of its particles were mainly "spherical" with a core surrounded by a shell. The sticking point, blocking tests, and examination of crushed particles with an optical and a scanning electron microscope showed that the shell made of polystyrene and the core mainly consisted of the polyurethane elastomer and the polyester.

Example 20

A solution of about 6.5 g of a polystyrene, about 5 * 0 g of a polyurethane elastomer (Estane 5701 from BP Goodrich) and about 1.5 g a polyester (Eppn 872 from Shell Chemical Company). The final concentrations were approximately 0.5 percent polystyrene, about 0.4 percent of the polyurethane elastomer, about 0.1 percent of the polyester and about 99 _s 0 percent of solvent. The solution was spray dried using a laboratory spray dryer 30.5 (12 inches) in diameter and a spinning disc atomizer operating at about 2,000 rpm and a feed rate of about 20 meters / minute. The temperature of the drying air was about 4O ⁰ C (I04 ° F) in the dry product, there was a powder having a volume-

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average particle diameter of about 12.0 microns. The electron microscopic examination showed that the individual particles were mainly spherical and had a core that was surrounded by a shell. old glue point, demonstrated the blocking tests and examination of crushed particles with an optical and a scanning electron microscope, that the shell made of polystyrene and the core consisted mainly of the polyurethane elastomer and the polyester.

Example 21

A solution of about 5.0 g of a polystyrene and about 5.0 g of a CLr diurea was prepared in a mixture of benzene and dimethylformamide (volume ratio benzene: dimethylformamide = 9: 1). The final concentrations were about 0.5 percent of the polystyrene, about 0.5 percent of the Cg diurea, and about 99.0 percent of the solvent. The solution was spray dried using a 12 inch diameter laboratory spray dryer with a spinneret operating at about 3000 rpm and a feed rate of about 40 ml / minute. The temperature of the drying air was about 50 ⁰ C (122 ⁰ P). The dry product was a powder with a volume average particle diameter of about 15.0 microns. The electron microscopic examination showed that the individual particles were mainly spherical and had a core which was surrounded by a shell. The sticky dot, blocking tests, and examination of crushed particles with an optical and scanning electron microscope showed that the polystyrene shell and the core consisted primarily of the Cj-g-diurea.

Example 22

In chlorobenzene with a small amount of benzophenone, a solution of about 10.3 g of a polystyrene and * about 1.1 g of a

30982 8 / 0.6 81

Polyacetaldehyde produced. The final concentrations were about 4.5 percent of polystyrene, about 0.5 percent of polyacetaldehyde, and about 95 percent of solvent. The solution was spray dried using a 12 inch diameter laboratory spray dryer and a spinning disc atomizer operating at about 24,000 rpm and a feed rate of about 5 ml / minute. The temperature of the drying air was about ¹ IO ⁰ C (104 ⁰ F). The dried product is a powder with a volume average particle diameter of about 14.0 microns. The electron microscopic examination showed that the individual particles were mainly spherical and had a core which was surrounded by a shell. The glue dot, blocking tests, and examination of crushed particles with an optical and scanning electron microscope showed that the shell was made of polystyrene and the core was mainly made of polyacetaldehyde.

Example 25

In a mixture of hexane, ethyl acetate and toluene (volume ratio Hexane: ethyl acetate: toluene = 50: 31: 1) became a solution of about 1.0 g of a styrene / n-butyl methacrylate copolymer (about 65/35 percent by weight) and about 5.0 g of a silicone rubber (W 98I from Union Carbide Corporation) at about 1 percent Benzoyl peroxide made. The final concentrations were about 0.3 percent of the styrene / n-butyl methacrylate copolymer, about 1.2 percent of the silicone rubber, about 0.01 percent of benzoyl peroxide, and about 98.5 percent of solvent. The solution was made using a 12 inch diameter laboratory spray dryer and a spinning disc atomizer, operated at about 33,000 rpm, spray dried. The inlet temperature of the drying air was about 25 ° C (77 ° F). During the drying process, cooling was started in order to facilitate the primary deposition of the silicone rubber core material.

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cheap. The electron microscopic examination showed that the individual particles were mainly spherical and one Have core, which was surrounded by a shell. The glue dot, the blocking tests and the examination of crushed particles with an optical and a scanning electron microscope showed that the shell made of the styrene / n-butyl methacrylate copolymer, and the core was mainly composed of the silicone rubber.

Although specific materials and process conditions above for the production of encapsulated materials by the method according to the invention are indicated, this is intended to mean the present Invention should not be limited in any way. Other wall materials, core materials, solvents, Substituents and methods other than those enumerated above can be used in place of those used in the preceding examples Materials and conditions can be applied with similar results being obtained. Otherwise, be on it pointed out that the present invention can be changed and modified in many ways without changing the framework the present invention can be relied on.

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Claims (1)

PATENT CLAIMS 1. Method of encapsulating a liquid, semi-solid or solid Core material in a shell material, characterized in that a single-phase solution of the core material and the shell material and this solution is spray-dried. 2. The method according to claim 1, characterized-in that one a shell material is used, the solubility of which is different from the solubility of the core material in the single phase solution is. 3. A method of encapsulating the substantially soluble portion of a core material in the substantially soluble portion a shell material with a solubility different from that of the core material, characterized in that, that he "(a) the core material and the shell material in at least one relatively volatile solvent dissolves to form a solution, (b) produces small individual droplets from this solution, (c) at least a portion of the solvent is removed from the individual droplets by evaporation, thereby donating the concentrate of the dissolved core material and shell material increased and practically all of the core material in the form of a low-solvent phase is deposited, and (d) removing additional solvent from the droplets, causing the shell material to precipitate around the core material with the formation of practically dry, small, spherical particles in which the core material of the shell material is surrounded spherically. Yy. Procedure according to. Claim 3, characterized in that the Core material, the shell material and the solvent in such a way 30 98 28/0681 that chooses a change in the concentration of the solvent and the core material and the shell material result in the core material being in the form of a low-solvent phase with a high surface tension in a solution of the shell material separates. 5. The method according to claim 3 and / or h _t, characterized in that the deposited in the form of a low-solvent phase with a high surface tension core material is surrounded with the solution of the shell material and a practically dry, solid capsule shell is formed by evaporation of the solvent. 6. The method according to at least one of claims 3 to 5 $, characterized in that the solvent is selected taking into account the solubility of the core material and the shell material in the solvent and the volatility of the solvent. 7. The method according to at least one of claims 3 to 6, characterized in that the solvent is one of several Solvents existing solvent mixture used. 8. The method according to at least one of claims 3 to 7, characterized in that the solubility of the core material and of the shell material determined in the solvent. 9. The method according to at least one of claims 3 to 8, characterized in that solvent combinations are used as solvents selected by determining the solvent ratio at the cloud point. 10. The method according to at least one of claims 3 to 9, characterized characterized in that a solubility range is determined which includes the solvents in which the core material and the shell material are soluble. 309828/0681 : - 61 11. The method according to at least one of claims 3 to 10, characterized characterized in that the solubility range is determined by a solution of the core material and the Shell material is titrated against a non-solvent and the cloud point is taken as the limit of the solubility range . . 12. The method according to at least one of claims 3 to 11, characterized characterized in that one uses a core material and a shell material each consisting of several substances. · 13 · Method of encapsulation, the essentially soluble portion a core material in the substantially soluble portion of a shell material, the solubility of which depends on the solubility of the core material is different, characterized in that '· (a) the core material and the shell material in a solvent dissolves to form a single-phase solution of the core material and the shell material, (b) produces small individual drops from this solution, (c) at least some of the solvent is removed from the individual droplets by spray drying the solutions, whereby the core material and the shell material are deposited one after the other in a separate phase, and (d) removing additional solvent from the droplets, causing the shell material to precipitate around the core material with the formation of practically dry, small spherical particles in which the core material of the shell material is surrounded in a capsule shape. Ik. ■ Method according to claim 13, characterized in that the core material phase is deposited at a higher concentration of the solvent than it is used to deposit the Hüll.en- 309828/0681 materials is required. 15 · The method according to claim 13 and / or Ι **, characterized in that that the solvent is a common solvent for the core material and the shell material during the removal thereof remains and the phase separation due to the incompatibility between the core material and the shell material is effected. 16. The method according to at least one of claims 13 to 15, characterized characterized in that a solvent is used which consists of several substances. 17 · Method of encapsulating the substantially soluble portion of the core material in the substantially soluble fraction of a shell material, the solubility of which depends on the solubility of the core material is different, characterized in that one (A) the core material and the shell material dissolve in mutually miscible solvents to form a Single phase solution of the core material and the shell material, (b) produces small individual drops from this solution and (c) at least some of the solvents are removed from the droplets by spray drying the solution, some of which Removal of the mutually miscible solvents in the ratio in which they are removed causes the phase separation of the core material and the other Removal of the miscible solvents results in the shell material surrounding the core material precipitates around. 18. Method of encapsulating the substantially soluble portion a core material in the substantially soluble portion of a shell material, the solubility of which depends on the solubility of the core material is different, characterized in that 309828/0681 -e- '■ man (a) Dissolve the core material and the shell material in a mixture of two solvents to form a single phase solution of the core material and the shell material, wherein a solvent of the solvent mixture is a The core material is non-solvent and is sufficiently concentrated by evaporation during drying can be so that there is the phase deposition of the core material causes prior to the deposition of the shell material, (b) produces small individual drops from this solution, (c) at least a portion of the mixture of the two solvents by spray drying the solution is removed from the droplets, creating the core material and the shell material successively subject to phase separation, and (.d) further proportions of the mixture of the two solvents removed from the droplets, whereby the shell material is deposited around the core material to form practically dry, small, spherical particles in which the core material of the shell material is capsule-shaped is surrounded. 19. The method according to claim 18, characterized in that the mixture of the two solvents during drying a solvent for the shell material remains. 20. The method according to claim l8 and / or 19, characterized in that that the polymeric reaction product of isopropylidenediphenoxypropanol as the core material and adipic acid, the shell material being the reaction product of a dimer acid and a linear one Diamines and a mixture of chloroform and isopropanol can be used as the solvent. 21. Method of encapsulating the substantially soluble portion a core material in the substantially soluble portion of a shell material, the solubility of which depends on the solubility. 309828/0681 of the core material is different, characterized in that that he (a) the core material and the shell material are dissolved in a common (reciprocal) solvent mixture Forming a single phase solution of the core material and the shell material, the common solvent mixture first a non-solvent for the core material and then a non-solvent during drying for the casing material, (b) produces small individual droplets from this solution, (c) at least a portion of the common solvent mixture by spray drying the solution from the droplets removed, whereby the core material and the cladding material successively undergo phase deposition, and (d) removing additional solvent from the droplets, causing the shell material to precipitate around the core material with the formation of practically dry, small, spherical particles in which the core material of the shell material is surrounded in a capsule shape. 22. The method according to claim 21, characterized in that during the final stage of solvent removal, a core material forming phase, a shell material forming phase, and a solvent phase coexist. 23 · The method according to claim 21 and / or 2.2, characterized in that that the polymeric reaction product of iso- -oT.
propylidendiphenoxypropaiy and adipic acid, polystyrene as shell material and a mixture of chloroform and heptane as solvent mixture. 2 ¹ J. A method for encapsulating the substantially soluble portion of a core material in the substantially soluble portion of a shell material, the solubility of which depends on the solubility. of the core material is different, characterized in that one 30982 8/0681 (a) the core material and the shell material in a solvent system from the group of water, ammonia and the volatile alkaline materials dissolves with formation a single phase solution of the core material and the shell material, (b) produces small individual droplets from this solution, (c) at least a portion of the solvent system is removed from the droplets by spray drying the solution, whereby the core material and the shell material are successively subjected to phase deposition, and. (d) removing additional solvent from the droplets, whereby the shell material is deposited around the core material with the formation of practically dry, small, spherical particles in which the core material is surrounded by the shell material in the shape of a capsule. 25 «Method of encapsulating the substantially soluble portion a core material, in the substantially soluble portion of a shell material, its solubility depends on the solubility of the core material is different, characterized in that (a) the core material and the shell material in a solvent dissolves to form a. Single phase solution of the core material and the shell material, (b) produces small individual droplets from this solution, (c) cools the individual droplets, creating at least one Part of the core material is deposited in the form of a separate phase from the solution, and (d) removing at least a portion of the solvent from the droplets, thereby causing the shell material to wrap around the core material around precipitates with the formation of practically dry, small, spherical particles in which the Core material is surrounded by the shell material in a capsule shape. 309828/0681 - 'efe 4 26. The method according to claim 25, characterized in that a vacuum is applied. 27. The method according to at least one of claims 1 to 26, characterized in that a solvent with a boiling point between about O ⁰ C and about 200 ⁰ C is used. 28. The method according to at least one of claims 1 to 27, characterized characterized in that the shell material and the core material are in a ratio of between about 99 parts by weight Shell material and about 1 part by weight core material and about 1 part by weight shell material about 99 parts by weight Core material used. 29. The method according to at least one of claims 1 to 28, characterized characterized in that the thickness of the shell is controlled by adjusting the proportion of the core material to the shell material varies. 30. The method according to at least one of claims 1 to 28, characterized characterized in that ran controls the thickness of the shell material deposited around the core material by controlling the size of the spherical, encapsulated particles. 31. The method according to at least one of claims 1 to 30, characterized in that the core material and the A colorant from the group of dyes and pigments is added to the shell material. 32. The method according to at least one of claims 1 to 31, characterized in that the size of the spherical, encapsulated particles to a value between about 0.5 and about 1,000 microns. 309828/0681