JPS5947232A - High molecular substance dissolution and device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (4) Technical Field and Prior Art It is difficult to rapidly obtain a homogeneous solution of water-soluble polymer particles in water. This is because it forms a film of concentrated solution, which causes the particles to stick together and coagulate. Once the aggregates form, they penetrate the drainage water very slowly;
As a result, a sticky mass of polymer is formed and the overall dissolution is very slow. This problem is particularly acute when the particles are small, for example between 0.1 and 10 μm in diameter.

If polymer particles are simply dispersed in water with stirring, significant condensation is unavoidable. To minimize this, it is known to add polymer particles to water in the form of a dispersion in oil or other non-aqueous liquids. It is well known that strong stirring is required and this stirring is carried out for a considerable period of time in order to improve the solubility M'fr.

A mechanical device suitable for achieving this purpose is U.S. Pat.
Katzer in No. 468,322
This is a T-joint with an in-line turbulence-inducing barrel arrangement as described in . Significant mixing occurs at the tee and melting begins at this point, but the melting system is then transferred to an elongated turbulence inducer for the purpose of improving contact and melting. The transit time between the T-joint and the outlet of the turbulence inducer is generally several seconds or more.

Although such a device is suitable for large particles, for example 10 μm or larger, a major drawback remains that when the particles are small, for example from 0.1 to 5 μm, polymer agglomerates are produced. Generally, when mixing such particles in water as a dispersion in oil, it is inevitable that some agglomeration will occur, so that a homogeneous solution will be less than 1 after a long dissolution time.
It's just a U that gets 41.

It is known that the addition of surfactants to the total dispersion or water that promotes the dispersion of oil in water greatly facilitates the dissolution of polymer particles. This is reflected in U.S.C.
Hawkins in issue 2,203
Published by = h and still British Patent No. 1.364,
This is contradicted in No. 873. Surface-active dispersants suitable for this purpose are described in their specifications and may be conveniently referred to as active agents. In addition to facilitating the dissolution of the polymer particles, especially when the particles are very small, the use of an activator is acceptable, e.g. to produce a polymer solution with the best properties as a flocculant. It's starting to look like this.

Despite these advantages of the active agent, the inventors have found that its use is associated with a number of disadvantages. First, the use of large amounts of active agent is costly and environmentally undesirable.

Second, the amount of activator must be carefully selected. Optimal results require selection of a critical amount of activator, which depends on, for example, water quality, water flow, chemical type of activator,
Polymer dispersion viscosity, intensity and time of agitation, and in water? The inventors have discovered that it depends on the reamer concentration. It is therefore not possible to administer the active agent at a single level - yielding optimal properties under all conditions encountered in practice.

Thirdly, is it to dispersion liquid + bamboo water? Homogeneous mixing (7) may be inconvenient or even difficult, making the dispersion unstable and/or resulting in blockage of the mixing equipment.

Orifice mixers are known to help mix immiscible liquids together.

In DE 2533108, there are examples in which an orifice mixer is used to mix a dispersion in a water-soluble [rimer] oil with water in the presence of an activator for the purpose of producing an aqueous polymer solution. It is clear that the orifice mixers used are conventional orifice mixers each having a 90 DEG feed inlet at one end of the mixing chamber and an outlet orifice at the opposite end of the mixing chamber.

The mixture emerging from the orifice passes with turbulence through a mixture containing a baffle plate located 4 meters from the orifice and then through a charging mixer. It is therefore clear that the orifice mixer is considered to perform only a portion of the total mixing required. The mixing chamber has a volume of 10 ccg and the total flow rate of the mixing chamber is (8
) 1025 ml 1 minute, from the time dissolution begins after first contact with the liquid until mixing is almost complete, ie the average residence time at the orifice is approximately 600 milliseconds. The subsequent mandatory mixing and baffle plate running times would be even longer.

Object and Structure of the Invention The inventors have discovered the surprising fact that the rate of dissolution and the quality of the final solution are strongly influenced by what happens at the time of first contact of the dispersion with water, i.e. during the first few milliseconds. I made a discovery. All previous attempts have ultimately utilized continuous light shearing and other mixing forces for concentration, but have not recognized the criticality of using these forces virtually simultaneously with contact. The method according to the present invention for dissolving polymeric particles, which are a dispersion of particles in a non-aqueous liquid, in water involves mixing the dispersion with water with sufficient stirring to begin substantial dissolution of the particles and water. and substantially uniformly dispersing the particles in the water dispersion within less than 100 milliseconds from the onset of substantial dissolution, and allowing the particles to complete dissolution in the water.

Description of Structure and Effects of the Invention It can be seen that substantial dissolution of the particles in water begins immediately after contact of the dispersion with water.

However, if the non-aqueous liquid is highly immiscible with water and the agitation is slow, the initial contact will result in laminar flow. This is because substantial dissolution begins only when the shaking and stirring progress and the water and the dispersion are completely mixed.

Substantially homogeneous dispersion of the dispersion in water is possible if substantially no agglomeration of the particles occurs before total dissolution of the particles in water takes place. Substantially homogeneous dispersions are usually mixed with a large amount of water (possibly an aqueous polymer solution) and complete dissolution occurs in this water rather than in the water used to form the initial mixture. It is done in the vine.

The substantially homogeneous dispersion becomes a dispersion broken up into substantially single particulate droplets. That is, each droplet of non-aqueous liquid in the resulting oil-in-water dispersion contains substantially one particle of polymer.

Although obtaining droplets with more than one polymer particle and evenly distributed droplets gives the best results, it is possible to obtain suitable results even if all droplets contain some polymer particles rather than a single one. can be obtained. Typically, each droplet contains no more than 500 polymer particles, most preferably no more than 100 polymer particles. The best binding is between 1 and 50, preferably between 1 and 5, most preferably 1, of each droplet.
It is obtained when it contains 2 polymer particles.

Obtaining a substantially homogeneous dispersion requires the application of vigorous agitation, especially high shear.

The dispersion is substantially homogeneously dispersed in water; the high shear required is generally in considerable excess over what the final polymer solution can sustain without undergoing polymer collapse. Therefore, the shear is applied for only the time necessary to achieve the desired dispersion, and the theorist's optimum would be to apply an infinite amount of shear in a very short period of time. However, in practice, shearing is carried out for more than a short period of time, until the protective oil phase is stripped from the individual polymer particles and they are wetted substantially independently.

High shear or other agitation can be accomplished by forcing the dispersion of water and polymer particles through a suitable device capable of applying suitable shear substantially simultaneously with contact. The application of shear is followed by the water and dispersion undergoing a rapid pressure drop. Typically this will be at least 1.4, generally at least 3, preferably at least 6 ky/crl
, L,, Bashige 6~12'plcrlz Shikashi, generally 15 kg/cry? It cannot be exceeded.

This pressure drop generally occurs within less than 50 milliseconds, preferably less than 25 milliseconds. This occurs as a result of the water and dispersion being forced out in a shear mixer with moving parts, for example with the rotating blades of an emulsifier. but,
The best results are most conveniently obtained by using mixers that apply electrostatic elements to the shearing, ie, do not have high speed rotating parts.

Substantially homogeneous dispersions are best produced by forcing the water and dispersion with one or more compressors, particularly by using orifice mixers to create large pressure drops. Thus, a preferred method is to place the dispersion and water into an orifice mixer, thereby making all of the contact between the dispersion and water possible, and ejecting the resulting mixture from the orifice within less than 100 milliseconds from the time of initial contact. Including. Contacting may occur substantially simultaneously with discharge from the orifice. This is because the mixture of water and dispersion is released substantially simultaneously when it is made, but generally the mixture is 2 + 3 before release.
Mi! It is created for J seconds.

The orifice mixer has a mixing chamber with a dispersion sump inlet, a water sump inlet and an orifice tube, each leading to the mixing chamber. As a result, the mixing of the water and the dispersion and the initiation of dissolution of the polymer particles in the water takes place in this mixing chamber. The orifice is narrower than the cross section of the mixing chamber just before it. For example, the orifice and the mixing chamber are generally substantially cylindrical, and the radius of the orifice is 505 mm larger than the radius of the mixing chamber immediately before it.
Less than 6 is typical, e.g. a mixing chamber radius of 20-40
25 to 33 inches, preferably 25 to 33 inches.

Shearing may occur solely as a result of extrusion from the orifice, or during the movement of the dispersion from the device to the orifice, or immediately (a few milliseconds) after the mixture is ejected from the orifice, as described below. A mixer may also be used as a shearer.

If shear is applied in addition to the discharge from the orifice, a substantially cylindrical outer housing (which may be a mixing chamber or a housing directed from the orifice) and a movable substantially Conveniently this is done by forcing the mixture 4 through a helical groove formed between the inner housing of the cylinder and the inner housing which is fitted with a shear helical winding, i.e. inside the outer housing. The plug is cleverly a cylindrical plug with a spiral groove formed on its outer surface.

Another advantage of using a shear helical winding is that it imparts a rotational motion to the mixture exiting the orifice mixer, which causes the mixture to flow substantially immediately after exiting the orifice, i.e.
The preferred result is to facilitate homogeneous mixing of the resulting oil-in-water dispersion and the bulk dilution water, which occurs within 2.3 milliseconds.

Agitation may continue after shearing (eg, in copious amounts of water), but as such will only be sufficient to break up the dispersion into the desired substantially homogeneous distribution.

The pressure drop between the point at which dispersion and water come into contact in the mixer and the point at which the discharged mixture obtains a stable pressure, for example as a result of being forced into a large volume of water, is high and very fast. I have to do it. This time should be less than 100 milliseconds, generally less than 50 milliseconds, and best results are obtained when the time is less than 25 milliseconds, and the necking time is less than 5 milliseconds, such as 5 to 10 milliseconds. Typically, during this short period of time, the oil dispersion and water dispersion medium will be mixed at least 1.4
, preferably at least 3, generally at least 6 kl/
is subjected to a pressure drop of i. The preferred pressure drop is approximately 6
~12, most preferably 7-11.5 ky/d (in the D range, but in some cases a pressure drop of 15' y/cn is desirable.

The shear required to disperse the dispersion from the start of dissolution or the start of other agitation is less than 20 milliseconds;
Most preferred is less than 10 milliseconds, with best results obtained between 0 and 3 milliseconds.

(15) The method of the present invention thus provides vigorous stirring or shearing substantially simultaneously with contact and only for a very short time, i.e., much more than the 600 milliseconds required before the onset of shearing in DE 24 33 108. U.S. Patent No. 3,46
It differs fundamentally from all known methods in that it takes orders of magnitude less time than the several seconds or more in conventional in-line mixing devices such as No. 8,322.

The inventor of the present invention is a conventional orifice mixer? If used to mix water and a dispersion of water-soluble polymer particles in a non-aqueous liquid, and if there is any obstruction to the flow rate of the dispersion to and from the mixer. It has been discovered that the dissolution of the polymer in the mixer is only partial and there is a risk that the mixer may become clogged with polymer cells. The inventor minimizes this problem by providing an inlet for the dispersion reservoir. The inlet therefore has a diameter in the orifice of the mixing chamber, for example from 10% to 50 inches of the diameter of the duct leading up to the orifice. When the dispersion flow (16) is interrupted, the polymer barrel will block the orifice, but since the orifice is narrow compared to the diameter of the duct, the dispersion flow will continue and push the plug of polymer gel out of the orifice.

Instead of, or generally in addition to, providing such an orifice, a valve is provided at the inlet of the dispersion reservoir at or near the point where it terminates in the mixer, so that during normal flow, the flow of dispersion This valve is opened, and when the flow rate decreases, the valve is automatically closed. for example,
A non-returning ball valve may be provided in the hollow where the inlet terminates in the mixing chamber, and more generally at a short distance upstream from that point, for example upstream of the orifice as described above. The valve energizes the pole and goal to close the inlet, and when the flow rate from the inlet decreases, the inlet? - means for allowing the inlet to be closed by the flow valve and open by the flow when the flow rate is used.

Although it is necessary to maintain the pressure drop at the selected value for optimal performance, the extrusion rate of the orifice mincer may be varied as required if the polymer dosing rate to the water is varied. This is difficult to do. Another feature of the invention is to control the pressure drop k9 across the mixer by adjusting the effective exit area of the orifice. This involves mounting an aperture plate adjacent to the orifice with an aperture overlapping the orifice but at a different VC center than the orifice, and rotating the aperture plate at 21 at orifice 6 to expose the desired effective exit surface of the orifice. can be sent away by

The opening plate or orifice offset may be rotated relative to the nozzle. The opening plate is fixed to the block forming the inner mixing chamber, the mixing chamber and the opening plate are rotated, and the opening plate is fixed to the housing forming the orifice mixer.

Particularly good results are obtained when the inlet enters the mouth of the mixing chamber away from the orifice and the chamber has a cross section that is substantially small compared to the sum of the purchasing sections of the first and second populations. obtained, thereby substantially enhancing the flow of liquid from the inlet as it passes through the mixing chamber and into the orifice.

The cross-section of the chamber may extend toward the orifice.

As mentioned above, the mixture exiting the orifice is preferably discharged substantially directly into the water.

For example, between the orifice (or the next shear helix) and the water collecting the droplets, there can be a gap of up to 2α, no more than 5 tyn, but preferably less than 1 ctn. The mixture can be discharged onto a baffle plate to more evenly disperse it in a large volume of water. Good 1
In this system, the mixture is dispersed from an orifice into the top of the inner@II chamber, which is communicated with the surrounding outer chamber by a generally horizontal powerful plate, so that the water and dissolved polymer flow down the inner chamber, and The entire outer chamber flows through its top outlet and is then further blended with dilution water. The choice of chamber size and flow rate determines the lysis time before use.

The dispersion used as a source of the polymer particles of this invention can be any dispersion of small, water-soluble particles in a non-aqueous medium. The particles may be dry polymer particles or particles of polymer solids. The particles may be prepared by solution polymerization, emulsion polymerization, suspension polymerization, or may be prepared in an oil phase state, or may be prepared separately and then added to the oil phase.

The term "dispersion" is a broad term that includes any system of particles dispersed in a non-aqueous liquid, whether or not the characteristics of the particles are such that the system can properly be called an emulsion. used in meaning.

Preferably, acrylic monomers are used, such as phase inversion polymerization (rev
ersed phase polymerizat
ion) to make polymer particles.

The particles are generally between 0.1 and 10 μm in size, with 0.3
A size of ~5 μm is most preferred. The dispersion may contain dispersion stabilizers or other dispersants. These may be included as in-situ polymerization of aqueous monomers dispersed in oil. The water may be removed, for example by azeotropic distillation after completion of the polymerization. In this case the polymer particles will be substantially dry.

However, the method and apparatus of the present invention can be used even if the particles are aqueous gels. Typically, the dispersion has a weight of polymer solids d
0.3 to 3, generally 0.75 to 1.5 parts by weight of non-aqueous liquid, and 0 to 10 parts by weight, generally 0 to 1.
Contains 3M parts of water absorbed in the polymer particles. The amount of water mixed into the dispersion to initiate dissolution, e.g. M' of the water fed to the orifice mixer, is generally from 50 to 1000, preferably from 100 to 30, per weight of polymer solids.
It is 0 parts by weight.

The method of the present invention can be carried out with or without the use of all activators, e.g. I discovered that. Regardless of the presence or absence of an activator, the present invention hydrates each particle substantially independently to rapidly ensure total dissolution, and the resulting solution is similar to that of conventional rf reamer dispersions. It is clear that the aggregation performance is improved compared to the performance obtained when dissolving using a stirring system.

In the accompanying drawings, FIG. 1 is a schematic diagram of one form of the device, FIG. 2 is a longitudinal sectional view of another form of the device with sheared helical windings shown in perspective, and FIG. 3 is a schematic representation of another form of the device. Device 1
4 to 7 are graphs showing the results obtained by the present invention in comparison with the results obtained by conventional shear mixing.

The apparatus shown in FIG. 1 below is a modification of a conventional air-water nozzle, in which the air supply path is replaced by a dispersion liquid supply path, and does not include any moving parts. In particular, this device constitutes a high shear nozzle 1 leading from a nozzle orifice 2 to a chamber 3. The nozzle 1 has a cylindrical body 4 with a tangential port 5 for water and an axial feed channel 6 for a reservoir of polymer dispersion in oil exiting from a feed orifice 7 . There is a spiral baffle plate 8 on the wall of the room that creates a whirlpool in the water.

The chamber 3 may be a gap in which the liquid mixture is sprayed, for example, into running water, but is preferably filled with running water, and the nozzle orifice 2 is used directly in the water.
1 is fixed to the lid 11 of a container 12 filled to the bottom with water,
It consists of an orifice mixer 10 with a gasket 13 between the lid and the container.

The mixer 10 consists of a housing 14 having a first population 15 and a second population 16 and forming an inner mixing chamber 17 leading to an orifice 18 .

A water supply duct 19 is inserted into the inlet 15. This inlet duct terminates in a nozzle 21, which is fastened with a screw 20 for fixing the water supply nozzle. Immediately in front of the nozzle 21, a shear helical winding 22 is installed in the duct. The shear winding is a solid cylinder that fits snugly into the bore of the duct 19 and has a helical groove 23 around its outer surface.

The second port 16 is fitted with a member 24 forming a cylindrical duct 25 terminating in the open end 26 of the mixing chamber 17 . cage 27
together with the member 24 constitute a number of folds 28, 29 parallel to the axis of the duct.

The helical spring 30 slides between a number of folds 29 and is guided by these folds to engage the sole 31.

As the dispersion flows through the lumen 25, the flow of dispersion displaces the tube 31 from the open end 26 of the duct, causing the dispersion to flow into the chamber 1.
Enter 7. If the flow of dispersion is slow, spring 30 snaps the gurl into open end 26 and seals duct 25 from entry of water from chamber 17.

The arrangement of the cage 27 and the corrugations 28, 29 is such that the flow of water from the duct 19 towards the orifice 18 is unobstructed.

The mixing chamber includes not only the area where the inlet exits but also the orifice 1.
It also includes a mixing region 32 that rotates coaxially with 8.

This region of rotation is a cylindrical passage containing a shear helix 33 (like helix 22, shown in perspective).

The helical winding is a solid cylinder that is loosely fitted into the mixing region 32 and has a helical groove 34 on its outer surface.

The mixer shown in FIG. 3 consists of a housing 40 containing a mixing chamber 41 formed in a mixing chamber block 42 coaxial with a first annular cavity 43 and a second coaxial cavity 44 . A water supply duct 45 and a polymer supply duct 46 are bolted to the housing 40. Duct 46 is a non-return valve assembly 47
The assembly consists of a pole 48 which is biased against a seat 50 by a spring 49, the pole ensuring that the flow of polymer flowing from the duct into the mixing chamber 41 is biased by the spring. - Close the duct at the seat when it reaches a level that allows the lever to be held in the seat.

The mixing chamber 41 opens into an orifice 51 in which the liquid streams mixed therein are directed into a duct 56 under high shear. Orifice 51 is coaxial with the mixing chamber. opening 5
An aperture plate 52 having a diameter of 3 is fixed to the block 42;
Orifice 51 and eccentric loading. Arm 54 is fixed to block 42 and is movable through radial groove 55 to rotate block 42 about its axis and rotate orifice plate 52 eccentrically with respect to orifice 51 .

The duct 56 includes shear helical windings 57 to impart a fast rotation to the flow passing through the duct 56, and the flow is discharged into the water for treatment.

EMBODIMENTS Refer to FIGS. 4 to 7 for the following embodiments. Each figure shows the settling rate of a 2-chamber clay suspension after addition of 3 m9/l of polymer. into the suspension to evaluate the development rate of flocculation performance]? Aggregation performance was evaluated 2 hours after addition of the lipolymer. In each of FIGS. 4 to 7, curve A is the curve obtained by carrying out the method of the present invention, and curve B is the curve obtained by the low shear mixing method described in Example 1. The activator of Example 2-4 is "Ethylan 55"
(Ethylan55).

Example-1 Polyacrylamide as a polymeric bone is prepared as a fine dispersion in oil by a phase inversion suspension polymerization method. The particles are substantially anhydrous as a result of azeotropic distillation of the dispersion, and the dispersion contains approximately the same amount of
3'f IJ Mama - Consists of oil, 4? Lima particles have an average size of 2 μm. One part of this dispersion was mixed with 99 parts of water using a kneading head as shown in FIG.
% activity yJ? A reamer solution was obtained.

The pressure drop between the entry point and the nozzle orifice 2 is approximately 8.
5yu//'□2 (125p, s, i), entrance point 7
The residence time between and orifice 2 was approximately 9.2 milliseconds. The orifice size was 9 diameters.

Under this condition, the size of the solution droplet formed by the orifice is approximately 220 μm. Experiments with the droplets emerging from the orifice showed that they contained microdroplets of non-aqueous liquid, and the diameter of these microdroplets was 2-4 μm. Each aqueous droplet contained an average of approximately 1 (27) microdroplets. Since 50 volumes of the polymer-in-oil dispersion are polymer, this indicates that each polymer particle is substantially independently wetted in each aqueous droplet.

The droplets further flow into a container 3 containing water and continue to dissolve.

A sample of the polymer solution was immediately evaluated for flocculation performance as described above and is represented by curve A in FIG.

As a control, a predetermined amount of the same polymer dispersion as described above was added to 8 oz.
A 0.5% active Hq IJ mom solution was prepared by pouring it into 1 liter of water. The container was immediately capped and shaken by hand for 10 seconds.

The solution was allowed to stand and flocculation performance was evaluated from time to time over a period of 2 hours. This is representative of low shear activation conditions, but the fourth
It is indicated by curve B in the figure.

Initial results were performed with polymer dispersions in oil without any chemical activators. FIG. 4 compares the rate at which cohesive performance is achieved for low-shear and high-shear activation methods.

Best (28) performance was achieved after 1 hour using high shear activation according to the present invention. Only low dissolution of the polymer was obtained under low shear activation, and only a slight improvement in the performance of the polymer was achieved after 2 hours of aging.

The experiment of U-Bay Knee Example 1 was repeated with the addition of 1% chemical activator to the polymer dispersed in oil. The results in Figure 5 show that using high shear activation, the best flocculation performance occurred after approximately 25 minutes. Under low shear activation, maximum performance required 1 hour to achieve, and flocculation performance did not reach the results when using high shear activation conditions.

Example 3 - The experiment of Example 1 was repeated with the addition of 2.5% chemical activator to the polymer dispersed in oil. The results in Figure 6 show that using high shear activation, the best flocculation performance was obtained after 10 minutes. Under low shear wave activation conditions, peak performance was less than that obtained with high shear activation, and the rate of development of cohesive performance was therefore slow, with full performance achieved after 20 minutes.

Example 4 The experiment of Example 1 was repeated with the addition of 5% chemical activator to the polymer dispersed in oil. The results in Figure 7 show that using high shear activation the highest flocculation performance was obtained after 20 minutes. Under low-shear activation conditions, the maximum performance was lower than that obtained under high-shear activation, and although the maximum performance was obtained quickly and the optimal result was obtained after 10 minutes, the development speed of cohesive performance was relatively low. low.

These examples show that the high shear method of the present invention uniformly gives better agglomeration results than those of conventional low shear methods even in the presence of an activator, and that the best results in the absence of an activator. Indicates that the

[Brief explanation of the drawing]

1 is a schematic diagram of one form of the device; FIG. 2 is a longitudinal cross-sectional view of another form of the device with a shear helical winding shown in perspective; FIG. FIGS. 4-7 are longitudinal cross-sectional views of two configurations of the apparatus; FIGS. 4-7 are graphical illustrations illustrating the results obtained by the present invention as compared to conventional shear mixing; FIGS.

Claims (1)

[Claims] 1. When dissolving the polymer particles of the polymer particle dispersion in the non-aqueous liquid in water by mixing them with water, the dispersion is mixed with water with sufficient stirring and the particles are poured into the water. 100% from the start of substantial dissolution.
Mi! A method characterized in that the dispersion is substantially homogeneously dispersed in water and the dissolution of the particles in water is completed in less than J seconds. 2. Subjecting the mixture to shear caused by a pressure drop of at least 1.4 ky/dl, preferably at least 6 ky/crl, during less than 50 milliseconds, or less than 25 milliseconds, from the onset of substantial dissolution. 2. The method of claim 1, wherein the dispersion is substantially homogeneously dispersed in water by applying the water. 3. The method according to claim 1, wherein the dispersion obtained is mixed with a large amount of dilution water substantially immediately after dispersing the dispersion in water. 4. A patent comprising forcing a dispersion and water into an orifice mixer, thereby bringing the dispersion and water into contact, and releasing the resulting mixture from the orifice within less than 100 milliseconds from the time of total contact. A method according to claim 1. 5. The pressure drop between the point of contact between said water and the dispersion and the substantially constant pressure of the mixture after discharge is at least 1.
．． 4 ky/crl, preferably at least 6 ky/crl
CI! 5. A method according to claim 4, wherein this pressure drop is obtained over a period of less than 50 milliseconds, preferably at least less than 25 milliseconds after contact. 6. The method of claim 4 or claim 5, wherein said liquid mixture is discharged substantially directly from said orifice into a volume of dilution water. 7. The orifice mixer has a mixing chamber having an inlet for dispersion and an inlet for water, and the outlet of the orifice communicates from the mixing chamber, and (a) the inlet for the dispersion is in the mixing chamber; ends as an orifice, and/
(b) The inlet of the dispersion reservoir near the point where the dispersion terminates in the mixing chamber includes a valve, the valve being opened by the flow of dispersion during normal flow and controlling the flow rate. Automatically close the inlet when the temperature decreases (to 1'
4. The method according to claim 4, wherein the method comprises: 8+Preferably, the pressure drop between the pressure at the point of contact between the water distribution and the dispersion and the substantially constant pressure after discharge from said orifice adjusts the effective exit area of said orifice. In addition, an aperture plate having an aperture bounded by the orifice at the center is provided in contact with the orifice, and the opening plate is rotated relative to the orifice to obtain the desired effective 1 value of the orifice.
1. The method as claimed in any one of claims 4 to 7. 9. The mixture is placed between the VC substantially cylindrical side housing and the movable substantially cylindrical inner housing to promote substantially homogeneous distribution of the dispersion into the water. The method according to any one of claims 1 to 8, in which pressing t13 is performed from the formed spiral groove. 10 The above dispersion contains 61 parts by weight of polymer solids, 0.
Formed by 3 to 3 parts of non-aqueous liquid and 0 to 1011 parts by weight of water absorbed by the polymer particles, 50 to 1000 parts by weight of water leaf 1 to be mixed with the dispersion to initiate dissolution. 10. The method according to any one of claims 1 to 9, wherein the oil-in-water dispersant is substantially absent. 11. Any one of claims 1 to 10, wherein the homogeneous dispersion of the dispersion in water is carried out by dispersing the non-aqueous liquid in water as droplets each containing 1 to 5 particles of polymer. The method described in Section 1. 12. A first volume of the mixing chamber defining a mixing chamber, into which the dispersion of polymer particles is placed in the non-aqueous liquid;
Jq in a non-aqueous liquid consisting of Kiji population in the mixing chamber containing water and the orifice from the mixing chamber.
l) In an orifice mixer suitable for dissolving polymer particles of a polymer particle dispersion in water, the orifice mixer (3) (a) terminates in the mixing chamber of the orifice; b) Near the location where the first population ends in the mixing chamber, with a burr? (c) means for biasing the orifice to close the inlet, including a non-returnable pulp so that the inlet is closed at the H-pole when the flow rate through the inlet falls; means for varying the exit area, preferably located adjacent to the orifice;
and an aperture grate having an aperture overlapping the merifice but having a different center from the orifice, and means for imparting relative rotation to the aperture plate and the orifice;
and (d) having a substantially cylindrical outer housing immediately before or after the orifice and a movable substantially cylindrical inner housing defining a helical groove between the inner and outer housings. An orifice mixer comprising at least one component selected from the above.