DE1966299A1 - Method of making a composite - Google Patents

Description

PATENT LAWYERS 8 MUNICH 8O, MAUERKiRCHERSTR. 48

Df. BfB Dipl.-Ing. Stapf, 8 MOnchwi W, MmwffcirdnrttraB «45 · Yours Z.ich »n Yours Sdirelbwi Unw Ziidwa 21 491 Dahin 24 · kUQt | 97I Lawyer file no. 21 491

Monsanto Company
St. Louis, Missouri / USA

"Process for the production of a composite material"

The invention relates to a method for producing a composite of oriented filler in one Polymer.

In a preferred embodiment, the present relates to Invention a method for orienting filler materials in a polymeric preparation. as well

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This invention relates in a preferred embodiment to a method for forming a force field in a Filler suspension in a prepolymer system through which the filler particles move in a uniform direction are oriented and polymerized the system for fixing the powder particles in their oriented position will. The invention also relates to a method for forming a force field in a filler suspension a non-viscous molten polymer, whereby the filler particles are oriented in a uniform direction and the semicircle is cooled in order to fix the powder particles in their oriented position.

! Stirring or moving or shaking liquids or powders in a container is usually done by mechanical devices, such as submerged stirring paddles that rotate or vibrate, co-operate with submerged stationary paddles a rotating or vibrating container and submerged blades or leaves and containers that move both rotate around each other as well as swing. In some cases where you can completely stir the liquid Wants to keep isolated, the stirring process is carried out avoiding stirring devices immersed in the liquid causes. For example, the physical

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Inertia of the contents mixing when the container is vibrated. Furthermore, "already mixing is carried out by means of a magnetic stirring element, usually a permanent magnet in the form of a rod, the rod being magnetically coupled to a rotating external magnet.

Attempts continued to be made to sound waves to be used for stirring liquids. One such method is described in U.S. Patent 2,693,394. Furthermore, acoustic-mechanical transducers were used to measure liquids without stirring to achieve conventional mechanical agitators. An apparatus of this type is shown in U.S. Patent 3 072 808. However, these methods all have the disadvantage that, strictly speaking, they apply to liquids are limited and can only be used for particulate materials. In addition, have the particulate materials that can be used generally have a high density, thereby correspondingly large-scale devices with regard to the force to be performed become necessary.

So far, numerous investigations have also been looked at- lent the controlled orientation of synthetic fibers

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serrf made by electrostatic devices, such as at. the production of fiber wallpapers. In this process, a strong, electrostatic field is used Orientation of the fibers used is substantially perpendicular to the surface of the paper or substrate Direction. Electrostatic dispersion and orientation processes have also been used in the textile industry Control of the fiber flow applied. However, in all of these prior art methods, the media used, gaseous non-conductors, such as air.

It is therefore an object of the present invention to provide a method which is capable of a uniform Dispersion of particulate material during polymerization of a liquid medium until its viscosity reaches a point where it is sufficient is large to prevent further movement and settling of the particles.

The method according to the invention is illustrated by the drawings explained in more detail, in which corresponding devices with novel features with regard to their shape, construction, Arrangement and combination for carrying out the method are shown.

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In the accompanying drawings (5 sheets) is;

Fig. 1 is a schematic illustration which explains the properties of the zeta potential and the zeta potential shows for an outer shell and an arrangement of ions around a particle;

Fig. 2 is a graph showing the effect of the decrease in "

electrical potential as a function of distance from the particle surface shows;

3 is a schematic side elevation of a reaction vessel for carrying out the method according to the invention;

4 shows a schematic side elevation of a reaction vessel for carrying out the method according to the invention rens showing a modified form of the electrodes used herein;

Fig. 5 is a schematic side elevation of a slightly modified form of reaction vessel for the implementation of the method according to the invention, the random Orientation of the particulate material in one

Lobt-conducting liquid medium shortly after the generation -. '., * Ti-: ~ i iilekirtüüiien field is shown;

9 ν ^fi %% * fi '■■ -' ^fi ? 9AD λβ, - .. - 6 -

6 is a schematic side elevation of the reaction vessel of Fig. 5, the distribution of the particulate material after the generation of the electric field according to a slightly longer duration is shown j

Fig. 7 is a schematic side elevation of the reaction vessel of Fig. 5 showing the distribution of particulate matter in a manner similar to that shown in FIG is illustrated in Figure 6, except after a longer period;

8 is a schematic side elevation of a reaction vessel; which is similar to that of Fig. 5, the arrangement of the particulate material being shown after all movement of the particulate material has ceased;

Fig. 9 is a schematic side elevation of another modification of the reaction vessel for carrying out the process according to the invention, the distribution of the particulate Material in a non-conductive liquid medium after the creation of an electric field will be shown;

Fig. 10 is a schematic side elevation of another

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modified form of the reaction vessel to carry out of the method according to the invention, wherein the distribution of the particulate material in a non-conductive liquid medium is shown when no electric field has been generated;

. FIG. 11 is a schematic side elevation of a reaction vessel, which is similar to that of Figure 10, wherein the distribution lung λ is shown of the particulate material after for 9 minutes, an electric field was generated;

FIG. 12 is a schematic side elevation of the reactor of FIG Figure 10, showing the distribution of particulate matter after 3 minutes a much stronger one electric field was generated in the reaction vessel;

Fig. 13 is a schematic side elevation of the modified form of a reaction vessel showing the distribution of the particulate matter is shown when no electric field has been generated in the reaction vessel;

Figure 14 is a schematic side elevation of the reaction vessel of Figure 13, showing the distribution of particulate matter after 1 minute an electric field was generated in the reaction vessel;

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Figure 15 is a schematic side elevation of the reaction vessel of Fig. 13 »where the distribution of the particulate Material is shown after an electric field has been generated for 10 minutes;

Figure 16 is a schematic side elevation of a reaction vessel with flat electrodes, showing the force field and the flow of fluid in it

17 is a schematic side elevation of a reaction vessel with pointed electrodes, the force field and showing the flow of fluid therein;

18 is a schematic side elevation of a reaction vessel with a flat and a pointed electrode; showing the force field and the flow of fluid therein, and

Figure 19 is a schematic side elevation of a reaction vessel with flat parallel plates that are the same Have the size of the reaction vessel and show the force field formed.

Definitions

Because the use of electrical phenomena for control

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the behavior of particulate material in one fluent medium is a relatively new field, it seems necessary to use the following definitions for here to give the terms used.

Electrostatic potential - the potential difference that occurs remaining in an electric field. In contrast to electromotive or electrokinetic forces, electrostatic effects or phenomena are the result of Coulomb forces. These effects are generally prevalent in a gaseous medium and can be used to control the movement of particulate materials in air such as in electrostatic paint spraying, fiber flocculation, xerography and electrostatic stencil printing.

Electrokinetic Potential - the potential difference that occurs in an electric field as a result of relative movement between a solid and a liquid at the substance / liquid interface, sometimes known as the zeta potential, which are electrokinetic effects or phenomena that accompany this relative movement

(1) electroosmosis, i.e. movement of a liquid along a solid in an electric field,

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(2) electrophoresis or cataphoresis, i.e. movement of one Pesticide suspended in a liquid in an electric field,

(3) streaming potential, i.e. formation of a potential difference between the inflow and outflow part of a fluid vein, which passes a solid, and

(4) Precipitation potential, i.e. the formation of a potential difference between top and bottom in a container in which a solid suspended in a liquid Powder gradually settles to the bottom.

Force field (field force) - a field or a region under the influence of an electrical force, where the electrokinetic potential makes a significant contribution to the total force and often predominates in the total force. While Coulomb forces can be present, electrokinetic forces resulting from the formation of a zeta potential are considerable.

Dispersion - a suspension of particulate material in a liquid medium in which the fibers or particles are not constricted by other particulate material and the particulate material can move in all dimensions.

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Orientation - a state of three-dimensional predetermined positional arrangement in a liquid medium.

Packing - the degree to which the particulate material fills a volume of space.

rod-like - particulate material - as "fiber" g

Are defined.

Mixing - the term "mixing" is used herein in its generally accepted meaning in the art, ie as combining or combining into a mixture or agglomerating or fusing to form a more or less homogeneous whole. This definition does not include the complete loss of identity of an element and elements such as fibrous material or particulate material must be distinguished. The term "mixing" includes the process of mixing, blending.

Aspect ratio - a comparative term obtained by dividing the nominal length by the nominal diameter (cross section) of the particulate material. (The effectiveness of reinforcement in composite systems is

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directly dependent on the aspect ratio of the particulate material used as filler).

Particulate matter (filler) - very small particles of a solid of a size sufficient to have physical and mechanical bulk properties of the solid. "Particles" are defined as particulate material with an aspect ratio less than 5, "fibers" as particulate material with an aspect ratio greater than 5. (In determining the aspect ratio of particulate material that is not circular in cross-section, the length of the fiber is compared to an equivalent diameter of a circle that has the same average circumference as the particulate material).

Whisker - a monocrystalline fiber.

Reinforcement - the term "reinforcement" is used here primarily with a view to improving the properties of an element in the mechanical or structural sense, such as improving strength, modulus, impact strength, creep (flow, deformation).

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Coupling "smi1tel" - a means which "is supposed to cause the surface of a reinforcing fiber to bond with a matrix", as in the pallet of aminosilanes.

thermoplastic - a resin plastic that can flow under heat and pressure without degradation, like polystyrene, polypropylene and the polycarbonates etc.

Thermosetting - a resin or plastic that does not flow under the conditions of heat and pressure without degradation, such as the phenolic, epoxy, polyester and polyimide resins, etc.

The present invention relates generally to a method in which electrokinetic phenomena are caused various physical and chemical changes can be used. In particular, this relates to Invention of orienting and packing of particulate

pourable materials in a liquid medium, such as a Prepolymer system. In general, the filler, which can consist of reinforcing fibers, into a liquid medium with a lower dielectric constant h & t, introduced and released in a predetermined position, in which it is held while the medium is solidified ii cooling or polymerization. In the bye it is possible to use a force field

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ORIGINAL _ _u

-H-

des, by, containing a particulate material liquid matrix is formed to obtain the following results:

1. Untangling the lasers

2. Disperse the fibers

3. Orientation of the fibers in the liquid medium according to, a predetermined pattern

4 ·. Mixing the fibers with the matrix without any noticeable physical damage to the fibers and

5. packing the fibers in the predetermined desired arrangement,

There are generally three different forces acting from a distance and acting to move particulate matter Material can be used. These are the gravitational, magnetic and electrical forces. These forces generally act individually on each particle or on each fiber and are not necessarily based on mechanical domes or the interaction of Particles. However, the gravitational and magnetic forces have different components, such as the need to that in a magnetic system either the particles or the liquid must be ferromagnetic, to achieve effective speeds au. In a similar way

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The use of gravitational forces has several disadvantages, such as the limitation of movement in practically only one direction. It has been found that electrical forces for a general Application are particularly useful.

To carry out the present invention, it is necessary to have an electrical power source for forming a Form potential difference in the container. The forces acting on the system that cause the fluid to flow contribute, act within a predetermined volume part of this system. The nature of the forces, their directions and their location depends on the size and shape of the kettle and that of the electrodes. The shape of the Kettle is generally determined by the shape and size of the final product desired. The shape of the electrodes depends on the desired distribution of the particulate material in the product. · The type of Forces, the directions and the position thereof are also influenced by the electric field and they are still dependent on the electrical properties of the system.

The main force that enables the unique results of the present invention is due to an electrical

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roped field generated within a liquid is formed under conditions such that electrokinetic effects arise. -The phrase "electrokinetic Potential "has been explained above and its functions can be seen from Figures 1 and 2. The electrokinetic Effects are to be understood in more detail when one imagines a particle in a solution.

A charge can be on the particle in different ways but it is usually the result of the absorption of ions from solution. The absorbed ions induce a charge with the opposite gate sign in the neighboring molecules and they become through the Ion-induced dipole attraction close to the surface held. A charge in the liquid is created by the attraction of ions of opposite charge the charged surface. Layers of opposite electrical charges are therefore formed as with one Capacitor. The. inner shell of this double layer is tight and compact, while the outer shell is loosened up and is diffuse, with a high concentration of ions near the inner shell and with an increasing distance ion concentration decreasing from the surface of the particle. The inner shell sticks wherever it goes moved, firmly attached to the particle, while the outer diffuse

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Shell of oppositely charged ions slightly stripped off can be.

The total potential drop between the surface of a particle and the main body of the solution can be divided into two parts, the first being the potential between the inner shell and the particle surface. The second portion, as similar zeta or electrokinetic Po denotes tential, relates to the potential drop within the outer shell, which extends from the outer edge of the inner shell to the body of the solution. This zeta potential with the diffuse outer shell and the arrangement of the ions around a particle is shown schematically in Fig. 1, in which X represents the surface of the particle and Y represents a point in the solution located at a distance. Pig. Figure 2 shows the extent to which the potential decreases as the distance from the particle surface increases.

A more detailed description of this effect can be found in the "Encyclopedia of Electro-chemistry" by Clifford A. Hampel, pages 471 to 475.

In the more detailed description of the invention Procedure is to be detailed in the drawings

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go, explain the practical embodiments of the present invention. File A ₁ denotes an electrokinetic dispersion and stirring system which generally may consist of a reaction vessel 1 (Fig. 3) "made of any suitable non-conductive material such as glass, quartz or various plastic and synthetic resin materials The upper end of the vessel 1 can be opened for the introduction of a non-conductive liquid and particulate material. A first electrical conductor or an electrode 2 is connected to the lower end of the reaction vessel 1 and protrudes into it in the manner shown in FIG. 1. This first electrode 2 can be sealed by a suitable, liquid-sealing sealing ring 3. A second electrode 4 is secured by a closure cap 5, which in turn is movably arranged at the upper end of the reaction vessel upper edge of the vessel 1 can be secured by a liquid-tight closure The electrode 4 is secured in the cap by a liquid-tight closure 6. Each of the electrodes 2 and 4 are in turn connected to a suitable power source for the electrical potential (not shown).

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Fig. 4 shows a modified form of the reaction vessel .Α «, which is designed according to a particular embodiment, wherein it is substantially similar to the reaction vessel A-. In the reaction vessel A ^, each of the electrodes 2 and 4 is substantially round in cross section and the opposite end surfaces are flat. In the present reaction vessel Ap, each of the electrodes 2 and 4 with conical shaped to the outside, exactly like entgegen- set identified enlarged heads provided 9 and 10. FIG.

Fig. 5 shows another modified form of reaction vessel A_ with a slightly different shape of the vessel as such. In addition, one of the Electrodes have a pointed end, while the opposite electrode has a round-shaped flat disc. When using this type of electrode, the flow of a medium and a distribution of the particulate Material. The effects of this type of reactor are described in detail below, along with further information.

These devices have a wide range of uses and are particularly useful for detangling and dispersing Fibers and whiskers that are "immersed in non-conductive liquids" are suitable without a substantial amount

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Fiber or whisker breakage occurs. The devices are also for moving or stirring non-conductive liquids and useful for mixing liquid multicomponent polymerizable systems. They also serve to to keep particulate material in polymerizable liquid media in dispersion. A particularly important one Use of these devices according to the 'method of The present invention is an orientation of dispersed rod-like particulate materials to effect in polymerizable liquid media.

Using the electric fields described here enables many unique results. If the electric Field is formed in a vessel that contains a liquid and a particulate material very noticeable and immediately occurring changes can be observed. Wake up to the formation of the electric field between Immediate movement of the liquid is detected on the electrodes. Generally there is the beginning in that every particle and every fiber seeks to untangle itself from the mass of particulate matter. The continued application of the electric field creates a condition through electrokinetic effects the extensive dispersion of the particulate material

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BAO ORiGlNAl.

and the fibers. This by itself causes a thorough mixing of the fibers with the base material (matrix). In addition, it should be noted that this mixing has a significant advantage over the mixing methods previously used according to the prior art. In that no physically active devices are used for mixing, no noticeable damage to the Paserraaterialien that normally occur with even slight g tem contact with a physically-acting element are formed. By adjusting the electrodes in a manner as will be described in detail below, it is possible to obtain any desired orientation of the fiber material and the particulate material in the liquid medium. In addition, by suitable selection and positioning of the electrodes, it is possible to obtain dense fiber packings in a predetermined desired arrangement. The knowledge of these phenomena and the essential hell that the electrokinetic forces play in their formation leads to many possible uses, especially in the case of reinforced plastics, as will be explained below.

One of the most important uses of the one described above Devices and methods consists in the formation of a composite material from fiber-reinforced plastic

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_ ₂₂ _ 1366299

substance, i.e. a polymeric preparation that regulates contains oriented fibers, being made from a mixture of filler with a prepolymer system will. In this process, a force field is used on the final mix to turn the filler into the desired Orientate and hold a position. The force field is maintained until essentially polymerization occurs so that the filler is held in an oriented position with no contribution from the force field, whereafter abandoned the force field and the polymer can finally be cured. The term "prepolymer system" as used herein includes both monomers such as prepolymers with suitable catalysts, initiators, inhibitors, regulators, curing agents etc. The method of the present invention additionally comprises mixing a filler with a non-viscous melt of a polymerizate using a force field used in the obtained slurry for orientation of the filler and the slurry with the oriented one Filler is cooled to at least a temperature at which the polymer is sufficiently viscous to to hold the filler in an oriented position without the aid of the force field. After that, the force field can be removed and the polymer can be further cooled.

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BATH ORIGINAL

The position of the force field depends to a large extent on the shape and type of the end product. Since the greatest possible reinforcement of the filled polymeric preparation is achieved in the directions which run parallel to the orientation of the filler, it can "especially in the manufacture of objects in complex
Molds, it may be desirable to use separate force fields at the different sections of the molds, in order to achieve a filler orientation that provides optimal overall reinforcement of the article.

The strength of the force field required depends on many factors, such as the extent of the desired orientation, the amount, size and shape of the filler which is to be incorporated into the prepolymer or the polymer system, and the viscosity of the prepolymer
or polymeric medium and the heat generated by using the force field in the polymer system »The following examples describe some suitable force fields which can be used in the practical implementation of the invention. It is possible for the person skilled in the art, taking into account the properties that he desires in the end article, in connection with this description, stronger or weaker force fields with the same or
to use almost equal success.

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_ 1965299

Some of the filler materials that can be used in the present invention are particulate Materials · which can be either non-conductive or electrically conductive materials. The present invention provides a solution to the alignment and packing problems in the manufacture of fiber-reinforced Composites, in that the force fields used provide a unique way of packing the particles and depict their orientation without causing fiber damage. Some of the most essential Requirements for good alignment and tight packing of the particles are in the strong field areas of the system!

1) The dielectric constant of the suspended fibers must be considerably larger than that of the liquid;

2) the electric field used must be intense enough to cause sufficient agitation, and

3) the resulting agitation must be large enough to initially disperse the particulate material, and it must be allowed on the other hand not be so great that an intense electrokinetic Flow of the liquid is caused in the last stages.

The filler material should preferably have a dielectric constant have which is at least 1 1/2 times greater than the dielectric constant of Liquid.

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BATH ORIGINAL

1965299

In the case of a system selected, the particulate material should be: quartz and other forms of silicon dioxide such as dehydrated silica sol, "fumed silica", silica gel, glass fibers, gristobalite, etc., mineral silicates such as wollastonite, spodumene, mica, mullite, sillimanite, asbestos such as earcidystotile and , Forsterite and hercynite, clays such as kaolinite, dickite, hacrite, beidellite, bentonite, hectorite, montmorillonite, nontronite _? Saponite and attapulgite, metals such as iron, cobalt, hiekel, aluminum, sense, lead, magnesium, calcium, strontium, barium, titanium, zirconium, vanadium, chromium, manganese, copper and zinc, the corresponding oxides of the metals given above and other inorganic ones Materials like heavy metal phosphates, sulfides, and sulfates.

The filler can be in the form of particles or fibers. Particle-containing prepolymer systems are more pourable and deformable than prepolymer systems, '

which contain a corresponding amount of fibrous fillers. However, fibrous fillers are concerned with the structural properties like much greater improvements possible in terms of compressive, tensile, flexural and shear strength and the modulus compared to granular material. The fiber reinforcement also improves, especially with regard to impact resistance, toughness and creep, the dynamic

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1900299

mix mechanical properties to a much greater extent than in the case of granular material. The filler systems can therefore be formulated in such a way that they optimally achieve the desired properties of the respective end product Y / eise deliver.

The bonding of the filler to the cured polymer can be achieved by simple, mechanical bonding by means of physical Forces can be achieved or the filler can be in the polymer by one in the prepolymer system contained coupling agent, which both with the filler and the polymer to form a chemical bond reacts, present chemically bonded.

A prepolymer system can have a proportion of orientable filler together with a proportion of a non-orientable filler Contain reinforcing agents. Optimal proportions of polymer to non-oriented reinforcing agent Preparations which can be poured or shaped (for example by injection molding) can be formed into an oriented filler with very high strength, high modulus and high impact resistance.

The proportion of filler to be used depends on various requirements, such as the processability of the

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ORIGINAL BATHROOM.

19CG299

set (Yerbund) mixtures or the further processability of the end product, the prepolymer system intended for use, the particle size and shape, the design of the deformation device, the type and strength of the force field, the specific gravity of the filler and "especially the degree of reinforcement required," . Depending on these and other factors, the filler can range from about 5 to about 95 wt -.. $> be the Endzube- like reitung a preferred range that is useful for achieving a significant strengthening in the implementation of this method is in the range from about 40 to about 90% by weight of the total preparation. If no filler orientation is provided in the reinforcement of the polymer, a lower range of filler concentration from about 5 to about 50% by weight may be preferred.

The polymers useful in the present invention include synthetic and natural resin materials, which are sufficiently liquid or when heated to the movement of the filler particles after creation to enable a force field in the filler-polymer mixture in an oriented position. It belong also the monomers or prepolymers of synthetic thermoplastic and thermosetting resins with a

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BATH

19CG299

Flow viscosity in a range that allows for the movement of the bulking material particles into an oriented position after application 'a force field in the filler-monomer or Allows prepolymer mixture. Particularly preferred polymers have relatively high flexural and tensile strengths and moduli without amplification. Such polymers include, for example, thermosetting resins such as the polyesters, polyimides, phenol formaldehydes and epoxy resins and thermoplastic resins such as the vinyl polymers or copolymers, the polycarbonates and the like. However, other resin systems can normally be used for purposes where properties other than strength and rigidity are desired, increased and expanded Have utility when packed or reinforced in accordance with this invention. Such polymers include polyolefins, polyvinyl chloride and polyurethanes.

After the particulate material in the force field Once oriented and embedded, the matrix can then be polymerized in any conventional manner. For example, if this is a hit-curable matrix, the use of heat on the catalyzed System cause hardening of the matrix. The polymerization processes used in this invention are

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borrowed and therefore neither explained nor explained here in detail described. However, it is also possible to carry out the polymerization reactions according to the method and apparatus of To expedite the applicant (attorney's file 18 993). This type of polymerisation forms the subject of another Invention and is neither explained nor described here.

The size and shape of the electrode is determined by the desired size and shape of the final product. The electrodes must be made of an electrically conductive material such as copper or stainless steel. However, it will be different specific material intended for use is determined by the system. The electrodes can be in direct contact The two surfaces of the electrodes can be in contact with the liquid or as a modification be isolated from the liquid medium by air, a vacuum or a solid dielectric. But when the electrodes are isolated from the liquid, higher voltages are required.

The flow of liquid dielectrics as a result of the build-up of an electric field, as in the present invention used results from a number of factors. The liquid usually contains at least Traces of ionizable material, such as water, which under

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the influence of the field is decomposed. Furthermore, ions can enter the electrode surfaces through electrochemical reactions are formed. These ions tend to move in the direction of the electrode regardless of their origin of the opposite charge and at the same time with the more polar groups of the liquid dielectric to interact electrostatically, thereby pulling the molecules with them. Generally the ions have opposite charge, unequal size, charge and ability to form complexes with the dielectric molecules. As a result a relatively rapid flow of the liquid towards an electrode develops in the areas the greatest field strength. The return (the cycle) of the liquid takes place in exactly the opposite direction to or in areas of relatively weak field strength. This occurs when the field strength is not uniform is.

The flow of the liquid also occurs in the presence of the electrical double axis described above the phase interfaces. The passage of a small amount of free charge from the liquid near or at the Interface on the Featatoffoberfläohe represents a reduction in free energy in the system. If in the System an electric field is built up, the

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Solid will receive a force in one direction and the diffuse, charged layer will flow with the liquid close to the interface in the opposite direction, usually along the interface. This effect ,, which is also known as electroosmosis, is easily observed in the cell walls in systems where the non-conducting liquid has a very low conductivity and the effects as a result of the lonentrans- λ ports are very low. The liquid moves in the circuit away from the phase interfaces in areas depending on constrictions, which are formed by the cell shape, and on gravitational forces. When particulate solids are suspended in the liquid, the particles move qualitatively as one would expect from electrical double layers. Normally, however, the circulation of the liquid in a closed system quickly disrupts the flow pattern of the suspended particles resulting from electrical forces. Furthermore, the image of the normal electric double layer is completely superimposed when the suspended particles touch the electrodes and receive a strong opposite charge.

Another phenomenon of the flow of the non-conductive liquid is important. In a heterogeneous system

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(like "for a particulate dispersed in a liquid Solid content), in which a non-uniform, electric field is built up, becomes an energy minimum achieved when the flow lines of the electric field through a maximum volume of material with high dielectric constant. This has been mentioned earlier. If the dielectric constant of the solid material is considerably larger than that of the liquid, the particles in the areas will be relative Weak field strength migrate to such stronger field strength, whereby they displace the liquid until the Flow mass passing through the solid phase has reached a maximum. Similarly, the liquid becomes tend to displace solid particles from the areas of high field strength when the liquid phase is the has a larger dielectric constant. Even in homogeneous solutions, the component can contain liquids of the highest dielectric constant tend to collect in the area of the greatest field strength. It can be accepted will be that solid conductors in such systems have a substantially unlimited dielectric constant.

Rod-shaped particles with a high dielectric constant, which in a liquid with a lower dielectric constant

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BAD ORiQiMAI,

trizitätskonstante in which an electric field is built up, are dispersed, tend to also be forced in an axial direction with the leldströmungslinien from ä.en same reasons as the move Leuchen from weak to strong field regions in non-homogeneous fields. If these particles are aligned with the field, with the other conditions remaining the same, the liquid-particle system has lower f

Energy, i.e. a larger rope the total length of the. Flow lines runs through a material with a higher dielectric constant than with random orientation. A System of this type can be viewed as a capacitor with a plurality of movable plates. If with one such capacitor a uniform voltage is used (as is generally the case in the present system is the case), it will tend to behave in such a way that there is a potential minimum between the interfaces and increase its capacity and energy storage.

Although the particle-liquid system in which there is a constant electric field flow, there is no decrease experiences of free energy as the particulate material aligns with the field and toward the stronger field moves, the energy of the entire capacitor (which holds the charged electrical

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■ _ 1965299

which includes) during this process 201. To the extent that as the migration and alignment progresses, so will the Capacity increases and the charge is supplied to the electrodes, which at constant voltage increases the in the capacitor stored energy corresponds to:

E = 1/2 CV ² = 1/2 QV = 1/2

where E = energy of the charged capacitor in joules

V = the voltage with which the capacitor is charged

Q = the charge stored in the capacitor in coulombs and

C «is the capacitance, coulombs per volt.

A strong flow of the liquid can therefore be caused in many dielectric liquid systems be that one uses strong, non-alternating and generally non-uniform electric fields. The energy requirements for such stirring appear to be about the same, and possibly something less than if one wanted to achieve similar success after conventional mechanical stirring. The electrokinetic ^ However, agitation has certain advantages in the manufacture of composite materials, local ones high shear and impact forces lead during the mechanical

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Niche stirring process with whisker or short-fiber dispersions often results in a substantial proportion of the
Particle breaks. This can be avoided in the electrokinetic stirring, because the individual particles relatively mild, non-mechanical forces are subjected to and the secondary shear forces arising from the flow and particle-particle interactions' also not Λ are approximately as heavy as in the mechanically stirred systems.

As mentioned earlier, the size and shape of the electrode will depend on the desired size and shape of the final product
certainly. It also affects both the size and shape of the electrodes and the size and shape
of the vessel the force fields to a large extent, which in turn determine the flow patterns of both the liquid media as well
affect the fiber media. These effects are explained in detail in FIGS. 16-19.

16 shows a reaction vessel A. with an essentially flat pair of electrodes 21, 22. the
Electrodes are much smaller in diameter than the cross-sectional diameter of vessel A .. The lines of force,
which occur when a potential is built up between the electrodes are indicated by the solid lines.

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draws. The pasers could initially be like that flow as- it is essentially through the dotted Lines is shown. The lines could then be oriented along the lines of force. The liquid would as well flow in accordance with the lines of force.

The Pig. Figure 17 illustrates a modified shape of a reaction vessel A ₁ - having an upper electrode 24 and a lower electrode 25 which have relatively sharp tips. In this type of electrode system, the field strengths expand in a very narrow pattern between the two electrodes and do not tend to fill a large part of the diametrical cross-section of the vessel.

18 shows a vessel Ag with an upper, pointed electrode 27 and a relatively flat lower electrode 28. The lines of force formed by these types of electrodes show the image represented by the solid lines. It should be noted that the lines of force are more concentrated at the tip of the electrode 27 and that they tend to spread out at the lower electrode 28 as well. The passers also tend to have a spatial distribution that is roughly coincident with the force field. It is to be noted that the pointed electrodes tend to cone the field eu

2098U / 1282 " ⁵⁷ "

trieren, while the relatively flat electrodes form a much wider force field. Of course that's more focused sorry for the more intense.

A fairly uniform system arises in the case of the heating vessel A ^ that in Pig. 19 explains iet and relative has flat electrodes 30 and 31. In this vessel the electrodes 30 and 31 are the same diametrical Size as the vessel. If the electrodes 30 and 31 are completely parallel to one another, the lines of force can expand uniformly between the two electrodes »

On the basis of the force field and flow images described, it is possible to determine the effects of the movement of the particle Material occurring phenomena to be explained here in detail. In fact, there is initially an arrangement; in the form of a voluminous mass, with the particles TOI
pulled Qt

of the earth to the lines of the strongest part are driven, namely to the lines of force,

which run directly between the two electrodes » Of course, a stronger force field is required for concentrated systems.

If the hawkers have a total zeta potential,

201114/1192 ^{0RK3! NAL} inspecteo

in the,

- 5ο -

they will move towards an electrode. The particles will tend to migrate to the electrode that is oppositely charged *. Of course it will the system evolves towards the state with the least free energy. There are actually two states of free energy affecting each of the particles. The first of these states is the free energy that helps orient the fiber in the field and the second is the free energy that acts on the migrations of the fiber as a result of the charge on it.

It has been found according to the present invention that the energy required for such agitation, i.e. for agitation of the particulate material through the liquid, is often about the same or possibly less than that of conventional mechanical agitation to get a similar result. Since “electrokinetic” stirring is common in fell cases occur in many areas in the manufacture of composite materials. Too much more effective Possible uses of this · unique · * process » belong to the system

Contains fibers or whiskers and the production of g

f
goaetntn objects by means of a polymerization in

situ. With mechanical stirring · »of whiskers or short * ·

20ISU / 12S2. "

ORlQlNAt iNSPECTED

fibrous dispersions usually experience high local shear and impact forces, causing a substantial Fraction of particles breaking occurs. However, this breaking occurs in the electrokinetic stirring in which the individual particles and fibers are subjected to moderate, non-mechanical forces and those from the flow and the secondary mechanical forces involved in particle interactions are not very strong reduced or mostly avoided completely.

The invention is further illustrated by the following, non-limiting examples.

B eiaplel 1

ThisB example explains the use of a pretty inconsistent electric field to form a relatively rapid flow of the liquid in the areas high field strength towards an electrode and the strong circulation of the liquid in the opposite direction in the areas of relatively weak field strength. In Fig. 4- a vertically arranged cylindrical Pyrex reaction vessel, which has a circular horizontal cross-section, with methyl ethyl acrylate monomers, the Contains 25 ppm hydroquinone and a trace of water.

2098U / 1282 " ⁴⁰ -

In this system were 6.3 mm thick flat head screws Introduced as housing electrodes. The creation of a static electric field of several hundred yoIt per cm showed a noticeable flow. With several a thousand yoIt per cm a violent heat occurred in the area high field strength between the screw heads.

Example 2

The following example illustrates the orientation of particles and rapid stirring in a graphite particle containing Hylon flake system. With this particular system a relatively short, vertically positioned Pyrex reaction vessel was used. The reaction vessel also had a circular horizontal cross-section. The container of the reaction vessel had an inner diameter of 76 mm and the top electrode or anode was made by grinding a sharp point on a 6.3 mm thick Bolts made of stainless steel. The lower electrode or cathode consisted of a 25 »4 mm 3» 1 mm strong washer, which was attached to the end of a 6.3 mm thick bolt, with all parts made of stainless steel was. The distance from the tip of the upper electrode to the center of the lower electrode was 2.1 cm. That Vessel was filled with a carbon tetrachloride-hexane mixture

- 41 -

filled and in this mixture, were graphite-containing Nylon wallpaper flakes (1.0 mm long, aspect ratio: 60) suspended. The solvent had a density of 1.14 g per ml. Fig. 5 shows the statistical distribution of the fibers in the non-conductive liquid before the build-up of an electric field, Fig. 6 shows the orientation and packing the fibers around the electrode after applying a field strength of 2000 volts for 3 minutes. Fig. 7 shows the packing in random orientation of the fibers after an electric field of 2000 yoIt 9 minutes was generated. It can be seen from Figures 6 and 7 that some of the nylon flake particles containing graphite particles are at the electrode, but it can be seen that the dispersed fibers are rigid and aligned along the field flow. In this system only a split second was needed to to let the fibers jump into the array. Fig. Shows the close packing of the fibers in the region of the maximum Flow at 20 minutes after applying 23,000 volts.

The result of this experiment shows that certain preconditions for a rigid alignment and an effective, close packing must be given in the field area of high strength, such as the condition that the electrokinetic currents

2098U / 1282 " ⁴² "

SAD ORIGINAL

tion of the liquid must be relatively low. The particles become rigid after the electrical during the procedure Field aligned and follow the individual flow lines even if it is curved lines that are several times longer than the electrode spacing.

Example 3

A reaction vessel similar to the reaction vessel of Example 1 was used, and methyl methacrylate monomer was charged into the reaction vessel. 0.79 mm long "©" glass fibers were added to the liquid monomer. The reaction vessel was made of glass, had an inner diameter of 25 mm and an electrode spacing of approximately 3 cm. The minimum potential in the housing was H 000 volts direct current between the electrodes. Immediately after the tension was built up, the liquid circulated vigorously in the housing and the tangled pile of fibers was dispersed in the liquid after a few minutes. In the meantime, the dispersed fibers began to collect at the anode and after about 10 minutes the fibers in the housing assumed approximately the position shown in FIG. At the housing potential of H,000 volts direct current, the glass fibers moved from the lower to the upper electrode and collected there. At 20,000 volts DC

209814/1282 \ " ⁴³ "

ORFOLNAL INSPSCTEO

After about 10 minutes, the particles assume the arrangement illustrated in FIG. 9 and are longitudinally aligned according to the electric field.

There was no tendency for the fibers to be pushed away from the pile by the rapidly circulating fluid. The power was then turned off and the fibers allowed to settle to the bottom of the housing. It became cumene hydroperoxide (0.103 ml in 70 $ solution) and then an equivalent amount of triethylboron pyridine complex in η-hexane was added.

After a potential of 23,000 volts had built up in the housing, there was considerable mixing and an initial current observed from approx. 2 10 amperes. The casing current gradually decreased as the fibers at the anode collected. The mixing with the current also decreased and after 20 minutes there was no agitation more sufficient to move the remaining amount of loose fibers from the bottom of the case.

60 minutes after adding the free radical initiator and After the electrical field had built up in the housing, the liquid phase had become extremely viscous and it entered bubbles in the space between the electrodes. To this

2098U / 1282

At this point, the applied electric field was turned off and a stream of air was directed onto the glass tube in order to keep the strongly exothermic reaction under control. After cooling for one hour, the case was placed in an oven of 100 ⁰ G for 30 minutes to terminate the polymerization. After cooling to room temperature, the glass jacket was removed and the sample was cut through in a plane perpendicular to the electrode axis. The cut-off surface of the upper piece with the anode still intact was polished and examined microscopically under 500-fold magnification. Only ends of glass fibers could be seen, which shows the alignment with the flow of the electric field. The fiber distribution was uniform and the packing fairly dense. Photomicrographs were then taken of a thin disk of the resulting composite material. The disk was polished and photographed with 165 and 320 times diametrical magnification. The photographs showed that the individual fibers had been aligned parallel to the built-up field. The few fibers that had collected around the shaft of the anode were again oriented radially to the electric field.

2098U / 178?

BATH

Example 4

This example summarizes the species the. various phenomena occurring in the force fields of the present invention.

A reaction vessel similar to the one illustrated in FIGS. 5 to 8 was filled with a mixture of carbon tetrachloride and hexane, and then to this mixture was added a quantity of titanium dioxide particle-containing nylon flakes, 1.01 mm in size and one Diameter of 0.177 mm. After the addition of the flakes, a force field of 2000 volts was created between the electrodes. Fig. 10 shows the distribution of the flakes before the application of the voltage. Fig. 11 illustrates the dispersion of the flakes after 9 minutes after the application of a voltage of 2000 V. Figure 12 illustrates the dispersion of the flakes after a further 3 minutes using a voltage of 23,000 V. Figures 13, 14 and 15 show how nylon flakes of the same diameter containing graphite particles are suspended in the same solution. a means, behave in a housing with different electrode shapes. Fig. 13 shows the dispersion of the flake material before the Anl egen the tension, Fig. 14 the diapering after 1 minute when using

BATH ORIGINAL

application of a voltage of 2200 volts and FIG. 15 the diapering after 10 minutes when using 2200 volts. In this last given case was the case 76.2 mm long and 76 »2 mm in diameter, a distance between the electrodes of 2 cm and a capacity of 1000 to 23,000 volts. Same attempts were made with glass and silicon carbide whisker fibers instead of nylon flakes »In one of the behavior of In a manner similar to nylon, these fibers were disentangled, dispersed when a strong electric field was generated and oriented.

It goes without saying that changes and modifications in shape, construction, arrangement and combination of the parts opposite dtn described here and executed embodiments can be made, deviating from the inventive idea without sound.

128

Claims (6)

Patent pending hy A method of making an oriented filler composite. in a polymer, characterized in that one mixes a filler with a prepolymer system by means of an electrokinetic ^ forces for orienting the filler, creating an electric field and brings about a polymerization of the mixture of oriented filler and prepolymer system, which is at least sufficient to the To hold the filler in place before switching off the electric field. 2. The method according to claim 1, characterized in that the prepolymer system is a polyester prepolymer system is used. 3. The method according to claim 1, characterized in that the prepolymer system is a polyimide prepolymer system is used. 4. The method according to claim 1, characterized in that the prepolymer system is an epoxy prepolymer system is used. 209814/1282 " ⁴ °" 5. "The method according to claim 1, characterized in that the prepolymer system is a vinyl prepolymer system is used. 6. The method according to claim 1, characterized in that the prepolymer system is a polyurethane prepolymer system is used. 2098U / 178 7. COPY