CN109880016B - Method for continuous preparation of water-in-oil high internal phase emulsion and polymer porous material - Google Patents

Abstract

The present invention relates to a method for continuously preparing a water-in-oil type high internal phase emulsion and a polymeric porous material. The solution obtained by dissolving the emulsifier in the hydrophobic monomer is used as the oil phase; the aqueous solution containing the electrolyte and the initiator is used as the water phase; the oil phase and the water phase are continuously added into the twin-screw extruder, and sheared by the twin-screw The oil phase and the water phase are fully emulsified to form an emulsion; after the oil phase and the water phase are fully emulsified to form an emulsion, the initiator initiates the hydrophobic monomer in the emulsion to obtain a polymer with a pore structure and adjustable pore structure and morphology Porous material. Compared with the prior art, the method of the invention is simple and feasible, can be used for continuous production of high internal phase emulsion, and obtains porous materials with special pore structure.

Description

Method for continuous preparation of water-in-oil high internal phase emulsion and polymer porous material

technical field

The invention belongs to the technical field of emulsion preparation and porous material preparation, in particular to a method for continuously preparing a water-in-oil type high internal phase emulsion and a polymer porous material.

Background technique

A high internal phase emulsion is an emulsion in which the volume of the dispersed phase accounts for 74.05% or more of the total emulsion. It has been widely used in the fields of food, fuel, oil recovery, cosmetics and porous materials. High internal phase emulsions are usually stabilized by 5-50% of the continuous phase nonionic emulsifier. Recently, nanoparticle-stabilized high internal phase emulsions have also been reported. High internal phase emulsions are usually prepared by gradually adding the dispersed phase dropwise to the continuous phase in the emulsification under the action of a stabilizer. The emulsification methods include mechanical stirring, magnetic stirring, shear emulsification, ultrasonic emulsification and the like. However, these emulsification methods are all batch type, that is, the emulsion is prepared by one kettle, one kettle or one bottle, which is not conducive to the stability of the emulsion product performance. So far, continuous large-scale preparation of emulsions has become an urgent problem to be solved in the field of emulsion technology.

In recent years, polymeric porous materials prepared by high internal phase emulsion template method have attracted wide interest in many fields due to their unique pore structure, high porosity and low density. Low dielectric constant substrates in medium, scaffolds for 3D cell culture in tissue engineering, carriers for catalysts and reactants in synthetic chemistry, etc., can also be used as templates for the preparation of inorganic porous materials. In the preparation of porous materials by the high internal phase emulsion template method, the stability of the emulsion and the uniformity of properties between batches of emulsion products are very important.

The stability of high internal phase emulsion is the focus of attention, which is affected by many factors. So far, there have been many reports on the effects of emulsion phase components, emulsifier properties and dosage, emulsion dispersion phase volume fraction, preparation temperature, and electrolyte concentration on the formation and stability of emulsions. To study the surface, in order to stabilize the high internal phase emulsion, the emulsifier must be able to quickly adsorb to the liquid-liquid interface, form a firm interfacial film, and be able to effectively reduce the interfacial tension of the two-phase interface in the emulsion. The stability of the emulsion belongs to the dynamic stability, which is stabilized by the mutual repulsion between the internal phase droplets. It is generally believed that nonionic emulsifiers stabilize HIPE through steric repulsion benefits. When a stable water-in-oil high internal phase emulsion is to be prepared, a nonionic emulsifier with low hydrophilic-lipophilic balance value, such as sorbitan monooleate (Span80, HLB=4.3), is generally required. In addition, the electrolyte also plays an important role in the high internal phase emulsion stability. The presence of electrolytes can weaken the interaction between emulsifiers and aqueous solutions, thereby increasing the interaction between emulsifiers and making them more ordered at the water-oil interface. Therefore, the addition of electrolyte can enhance the strength of the water-oil interface film, increase the elastic modulus and apparent yield stress of the emulsion, and then improve the stability of the emulsion. On the other hand, the electrolyte also inhibits the Ostwald ripening effect by reducing the solubility of the aqueous solution in the oil phase and improves the stability of the high internal phase emulsion. Although there have been many studies on high internal phase emulsions, their emulsification methods are still limited to intermittent production methods such as mechanical stirring, magnetic stirring, shear emulsification, and ultrasonic emulsification, which are not conducive to the stability of emulsion product performance. Therefore, continuous large-scale preparation Emulsion technology is still under development.

Chinese patent CN102838774B discloses a macromolecular-stabilized water-in-oil high internal phase emulsion of styrene, acrylic acid, and methyl methacrylate triblock copolymer as the precursor, and the low-density polymerization is prepared by the physical method of freeze-drying Methods of physical porous materials. The steps are as follows: adding styrene, acrylic acid and methyl methacrylate triblock copolymer into an organic solvent, stirring and dissolving to form a polymer solution, using the solution as an oil phase, and slowly adding a certain concentration of electrolyte aqueous solution as a water phase dropwise In the oil phase, under the action of mechanical stirring, a water-in-oil type high internal phase emulsion that is only stabilized by polymer macromolecules is formed. After being placed at room temperature for a period of time, the emulsion is directly frozen with liquid nitrogen to fix the morphology, and then frozen A low density polymeric porous material is formed after drying to remove water and organic solvents.

Chinese patent CN102838773B discloses a water-in-oil high internal phase emulsion stabilized by nanoparticles of styrene, acrylic acid and methyl methacrylate triblock copolymer as the precursor, and the ultra-low density is prepared by the physical method of freeze-drying Methods for polymeric porous materials. The steps are as follows: the electrolyte is added to the aqueous dispersion of styrene, acrylic acid, and methyl methacrylate triblock copolymer nanoparticles, and after the electrolyte is stirred and dissolved, it is used as the water phase, and then the water phase is slowly poured into the oil phase, and the Under the action of magnetic stirring, a water-in-oil type high internal phase emulsion was formed. After the high internal phase emulsion is placed at room temperature for a period of time, it is freeze-dried to form a low-density polymeric porous material.

Chinese patent CN102391416A discloses a method of stabilizing an oil-in-water high internal phase emulsion with inorganic nano-particle titanium dioxide, and polymerizing the emulsion as a template to obtain a hydrophilic polymer porous material. The steps are as follows: adding a water-soluble monomer, a water-soluble crosslinking agent, an electrolyte and an initiator into the aqueous dispersion of nano-titanium dioxide, stirring and dissolving, then adding a hydrophobic organic solvent dropwise and stirring to form an oil-in-water emulsion. Heating to initiate the reaction of monomers in the emulsion to obtain a hydrophilic polymer porous material.

The above three patents are all related patents on the preparation of water-in-oil high internal phase emulsion and the preparation of polymer porous materials previously studied by the inventors of the present application. Large-scale preparation of emulsions.

On the other hand, since Roberto Colombo and Carlo Pasqutti of Italy first developed co-rotating and counter-rotating twin-screw extruders in 1935, after more than 80 years of continuous improvement and perfection, twin-screw extruders have developed by leaps and bounds. , has been widely used in polymer processing industry and other industries. Although twin-screw extrusion has been widely used in the field of polymer processing and modification, its application in the field of emulsion preparation has not been reported.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a method for continuously preparing a water-in-oil type high internal phase emulsion and a polymer porous material in order to overcome the above-mentioned defects of the prior art.

The invention uses a twin-screw extruder to realize the continuous preparation of the water-in-oil type high internal phase emulsion and the continuous preparation of the polymer porous material.

The object of the present invention can be realized through the following technical solutions:

The present invention first provides a method for preparing a water-in-oil high internal phase emulsion by continuous extrusion, comprising the following steps:

The solution obtained after the emulsifier is dissolved in the hydrophobic monomer is used as the oil phase;

The aqueous solution containing electrolyte is used as the water phase;

The oil phase and the water phase are continuously added to the feeding port of the twin-screw extruder, and the water phase and the oil phase are fully mixed and emulsified through the shearing action of the twin-screw extruder. Phase lotion.

Further, the emulsifier is selected from one or more of the following substances: Span80, Span60, polyglyceryl alkenyl succinate or Hypermer T96.

Further, the hydrophobic monomer is selected from one or more of the following substances: styrene, divinylbenzene, 2-hydroxyethyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate -Ethylhexyl, lauryl acrylate, myristyl acrylate, laurate methacrylate, butyl acrylate, myristyl methacrylate, glycidyl methacrylate or ethylene dimethacrylate alcohol ester.

Further, the electrolyte is selected from one or both of sodium chloride or calcium chloride.

Further, the mass fraction of the emulsifier in the oil phase is 5% to 30%.

Further, the mass fraction of the electrolyte in the water phase is 0.5% to 3%.

Further, the oil phase and the water phase are continuously added to the twin-screw extruder in a volume ratio of 1:40 to 1:3, respectively.

Further, the screw speed of the twin-screw extruder is 50-350 rpm, and the temperature of the oil phase and the water phase in the twin-screw extruder is controlled at 20-50°C, preferably 30-40°C.

Further, the water phase also contains an initiator, the initiator is selected from one or both of potassium persulfate or ammonium persulfate, and the amount of the initiator is 1% to 3% of the mass of the hydrophobic monomer. %.

The purpose of adding the initiator is to make the final water-in-oil type high internal phase emulsion contain the initiator, so that under suitable initiation conditions, the hydrophobic monomer in the emulsion can be initiated by the initiator, and then the hydrophobic monomer in the emulsion can be obtained. Porous polymer material with tunable pore structure.

The present invention also provides a preparation method of the polymer porous material, comprising the following steps:

The solution obtained after the emulsifier is dissolved in the hydrophobic monomer is used as the oil phase;

The aqueous solution containing electrolyte and initiator is used as the water phase;

The oil phase and the water phase are continuously added to the feeding port of the twin-screw extruder, and the water phase and the oil phase are fully mixed and emulsified through the shearing action of the twin-screw extruder. phase emulsion;

After the oil phase and the water phase are sufficiently emulsified to form an emulsion, the initiator initiates the hydrophobic monomer in the emulsion to obtain a polymer porous material with pore structure and adjustable pore structure.

Further, the initiator is selected from one or both of potassium persulfate and ammonium persulfate, and the amount of the initiator is 1% to 3% of the mass of the hydrophobic monomer.

Further, the conditions for the initiator to initiate the hydrophobic monomer in the emulsion to obtain the polymer porous material are: heating the obtained emulsion to 60-90°C, preferably 70-80°C.

After initiating the polymerization of the hydrophobic monomer in the high internal phase emulsion and reacting to obtain a white solid, the solid product is washed with a rinsing solvent water, ethanol or a mixture of water and ethanol, and a porous material with a certain pore size can be obtained after drying.

Further, the emulsifier is selected from one or more of the following substances: Span80, Span60, polyglyceryl alkenyl succinate or Hypermer T96.

Further, the hydrophobic monomer is selected from one or more of the following substances: styrene, divinylbenzene, 2-hydroxyethyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate -Ethylhexyl, lauryl acrylate, myristyl acrylate, laurate methacrylate, butyl acrylate, myristyl methacrylate, glycidyl methacrylate or ethylene dimethacrylate alcohol ester.

Further, the electrolyte is selected from one or both of sodium chloride or calcium chloride.

Further, the mass fraction of the emulsifier in the oil phase is 5% to 30%.

Further, the mass fraction of the electrolyte in the water phase is 0.5% to 3%.

Further, the oil phase and the water phase are continuously added to the twin-screw extruder in a volume ratio of 1:40 to 1:3, respectively.

Further, the screw speed of the twin-screw extruder is 50-350 rpm, and the temperature of the oil phase and the water phase in the twin-screw extruder is controlled at 20-50°C, preferably 30-40°C.

The present invention continuously obtains a high internal phase emulsion with adjustable droplet size of the dispersed phase by adjusting the screw speed and the temperature of the barrel. The method of the invention is simple and feasible, suitable for continuous production, and obtains a high internal phase emulsion whose size and distribution of dispersed phase droplets can be adjusted.

The droplet size of the dispersed phase of the high internal phase emulsion was observed by optical microscopy, the morphology of the bulk polymer porous material was observed by scanning electron microscopy (SEM, S-3400N, JEOL), and the digital solid densitometer (EDS-300) was used to observe the morphology of the bulk polymer porous material. Determine its density. A balance and a vernier caliper were used to measure the mass and volume of the bulk polymer open-cell material and calculate the porosity.

The characteristics of the emulsion obtained by the method of the present invention, such as the size of the dispersed phase droplet, the pore size of the porous material, and the density of the porous material, are controllable.

The invention takes advantage of the good feeding performance, mixing and plasticizing performance, extrusion stability and other characteristics of the twin-screw extruder, combined with its forward-position conveying characteristics of materials, the twin-screw extruder is used for the first time in the emulsion Continuous preparation, especially continuous emulsification of high internal phase emulsions.

Compared with the prior art, the method of the present invention is simple and feasible, suitable for the continuous production of high internal phase emulsion and its polymer porous material, and meanwhile the twin-screw extruder can provide sufficient dispersion, distributive mixing, better temperature control, and It has good self-cleaning properties, therefore, the water-inclusive high internal phase emulsion and the polymer porous material prepared by the method of the present invention have higher quality and better process stability.

Description of drawings

Fig. 1 is the optical microscope image of the emulsion obtained in Example 1;

Fig. 2 is the scanning electron microscope image of the porous material obtained in Example 1;

Fig. 3 is the optical microscope image of the emulsion obtained in Example 2;

Fig. 4 is the scanning electron microscope image of the porous material obtained in Example 2;

5 is an optical microscope image of the emulsion obtained in Example 3;

6 is a scanning electron microscope image of the porous material obtained in Example 3;

7 is an optical microscope image of the emulsion obtained in Example 4;

FIG. 8 is a scanning electron microscope image of the porous material obtained in Example 4. FIG.

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

Example 1

To weigh 100 grams of span 80, add it to a mixture of 1600 grams of styrene and 400 grams of divinylbenzene, and the resulting organic solution is an oil phase. Weigh 300 grams of sodium chloride and 100 grams of potassium persulfate into 8000 grams of distilled water, and the resulting solution is an aqueous phase. The oil phase and the water phase were heated to 30°C, respectively, and then the oil phase and the water phase were added to the cylinder at a temperature of 30°C and a twin-screw speed of 350 rpm through a constant-flow pump at a feed rate of 1:3 by volume. in a twin-screw extruder. After the water phase and the oil phase are sheared by the twin-screw, the high internal phase emulsion comes out from the outlet of the extruder. The obtained high internal phase emulsion is heated to 70 ° C, the monomer in the high internal phase emulsion is initiated to polymerize, and the reaction is obtained to obtain a white solid, and the solid product is washed with a rinsing solvent water, ethanol or a mixture thereof, and dried to obtain a solid product with Porous materials with a certain pore size.

The size of the dispersed phase droplets of the high internal phase emulsion was observed by an optical microscope. The optical microscope image of the high internal phase emulsion obtained in this example is shown in Figure 1. According to Figure 1, it can be seen that the water separation phase droplets of the emulsion obtained in this example are The average diameter is 48 microns.

Scanning electron microscope (SEM, S-3400N, JEOL) was used to observe the morphology of the porous material. The SEM image of the porous material obtained in this example is shown in Figure 2. According to Figure 2, it can be calculated that the obtained porous material has a pore size of 47 microns.

The mass and volume of the obtained porous material were measured with a balance and a vernier caliper, respectively, and the porosity was calculated. The porosity of the porous material obtained in this example was 77%.

Example 2

600 grams of span 60 was weighed and added to a mixture of 1600 grams of 2-hydroxyethyl methacrylate and 400 grams of ethylene glycol dimethacrylate, and the resulting organic solution was an oil phase. Weigh 300 grams of sodium chloride and 300 grams of potassium persulfate into 10,000 grams of distilled water, and the resulting solution is an aqueous phase. The oil phase and the water phase were heated to 30°C, respectively, and then the oil phase and the water phase were added to the cylinder at a temperature of 30°C and a twin-screw speed of 100 rpm through a constant-flow pump at a feed rate of 1:4 by volume. in a twin-screw extruder. After the water phase and the oil phase are sheared by the twin-screw, the high internal phase emulsion comes out from the outlet of the extruder. The obtained high internal phase emulsion is heated to 70 ° C, the monomer in the high internal phase emulsion is initiated to polymerize, and the reaction is obtained to obtain a white solid, and the solid product is washed with a rinsing solvent water, ethanol or a mixture thereof, and dried to obtain a solid product with Porous materials with a certain pore size.

The size of the dispersed phase droplets of the high internal phase emulsion was observed through an optical microscope. The optical microscope image of the high internal phase emulsion obtained in this example is shown in Figure 3. According to Figure 3, it can be seen that the water separation phase droplets of the emulsion obtained in this example are The average diameter is 25 microns.

Scanning electron microscope (SEM, S-3400N, JEOL) was used to observe the morphology of the porous material. The SEM image of the porous material obtained in this example is shown in Figure 4. According to Figure 4, it can be calculated that the obtained porous material has a pore size of 27 microns.

The mass and volume of the obtained porous material were measured with a balance and a vernier caliper, respectively, and the porosity was calculated. The porosity of the porous material obtained in this example was 82%.

Example 3

200 grams of polyglyceryl alkenyl succinate and 100 grams of Hypermer T96 were weighed and added to a mixture of 1600 grams of 2-ethylhexyl acrylate and 400 grams of divinylbenzene, and the resulting organic solution was an oil phase. Weigh 200 grams of sodium chloride and 300 grams of potassium persulfate into 10,000 grams of distilled water, and the resulting solution is an aqueous phase. The oil phase and the water phase were heated to 30°C, respectively, and then the oil phase and the water phase were added to a cylinder with a constant flow pump at a feeding rate of 1:40 in volume ratio, and the cylinder temperature was set at 30°C, and the twin-screw speed was 150 revolutions per minute. in a twin-screw extruder. After the water phase and the oil phase are sheared by the twin-screw, the high internal phase emulsion comes out from the outlet of the extruder. The obtained high internal phase emulsion is heated to 70 ° C, the monomer in the high internal phase emulsion is initiated to polymerize, and the reaction is obtained to obtain a white solid, and the solid product is washed with a rinsing solvent water, ethanol or a mixture thereof, and dried to obtain a solid product with Porous materials with a certain pore size.

The size of the dispersed phase droplets of the high internal phase emulsion was observed by an optical microscope. The optical microscope image of the high internal phase emulsion obtained in this example is shown in Figure 5. According to Figure 5, it can be seen that the water separation phase droplets of the emulsion obtained in this example are The average diameter is 74 microns.

Scanning electron microscope (SEM, S-3400N, JEOL) was used to observe the morphology of the porous material. The SEM image of the porous material obtained in this example is shown in Fig. 6. According to Fig. 6, it can be calculated that the pore size of the obtained porous material is 68 microns.

The mass and volume of the obtained porous material were measured with a balance and a vernier caliper, respectively, and the porosity was calculated. The porosity of the porous material obtained in this example was 96%.

Example 4

To weigh 400 grams of sban 80, add it to a mixture of 1600 grams of glycidyl methacrylate and 400 grams of ethylene glycol dimethacrylate, and the obtained organic solution is an oil phase. Weigh 50 grams of sodium chloride and 100 grams of potassium persulfate into 10,000 grams of distilled water, and the resulting solution is an aqueous phase. The oil phase and the water phase were heated to 30°C, respectively, and then the oil phase and the water phase were added to the cylinder at a temperature of 30°C and a twin-screw speed of 50 revolutions per minute through a constant-flow pump at a feed rate of 1:5 by volume. in a twin-screw extruder. After the water phase and the oil phase are sheared by the twin-screw, the high internal phase emulsion comes out from the outlet of the extruder. The obtained high internal phase emulsion is heated to 70 ° C, the monomer in the high internal phase emulsion is initiated to polymerize, and the reaction is obtained to obtain a white solid, and the solid product is washed with a rinsing solvent water, ethanol or a mixture thereof, and dried to obtain a solid product with Porous materials with a certain pore size.

The size of the dispersed phase droplets of the high internal phase emulsion was observed by an optical microscope. The optical microscope image of the high internal phase emulsion obtained in this example is shown in Figure 7. According to Figure 7, it can be seen that the water-separating phase droplets of the emulsion obtained in this example are The average diameter is 30 microns.

Scanning electron microscope (SEM, S-3400N, JEOL) was used to observe the morphology of the porous material. The SEM image of the porous material obtained in this example is shown in Fig. 8. According to Fig. 8, it can be calculated that the pore size of the obtained porous material is 32 microns.

A balance and a vernier caliper were used to measure the mass and volume of the obtained porous material respectively, and the porosity was calculated. The porosity of the porous material obtained in this example was 81%.

The foregoing description of the embodiments is provided to facilitate understanding and use of the invention by those of ordinary skill in the art. It will be apparent to those skilled in the art that various modifications to these embodiments can be readily made, and the generic principles described herein can be applied to other embodiments without inventive step. Therefore, the present invention is not limited to the above-mentioned embodiments, and improvements and modifications made by those skilled in the art according to the disclosure of the present invention without departing from the scope of the present invention should all fall within the protection scope of the present invention.

Claims (5)

1. a method for preparing water-in-oil type high internal phase emulsion by continuous extrusion, is characterized in that, comprises the following steps: The solution obtained after the emulsifier is dissolved in the hydrophobic monomer is used as the oil phase; The aqueous solution containing electrolyte is used as the water phase; The oil phase and the water phase are continuously added to the twin-screw extruder, and the oil phase and the water phase are fully emulsified to form an emulsion through the shearing action of the twin-screw; The mass fraction of the emulsifier in the oil phase is 5%~30%, the mass fraction of the electrolyte in the water phase is 0.5%~3%, and the oil phase and the water phase are in a volume ratio of 1:40~1 : The ratio of 3 is continuously added to the twin-screw extruder; The screw speed of the twin-screw extruder is 50-350 rpm, and the temperature of the oil phase and the water phase in the twin-screw extruder is controlled at 20-50°C. 2. a kind of method for preparing water-in-oil high internal phase emulsion by continuous extrusion according to claim 1, is characterized in that, described emulsifier is selected from one or more in following material: Span80, Span60, Polyglyceryl alkenyl succinate or Hypermer T96; The hydrophobic monomer is selected from one or more of the following: styrene, divinylbenzene, 2-hydroxyethyl methacrylate, 2-ethylhexyl acrylate, 2-ethyl methacrylate Hexyl, lauryl acrylate, myristyl acrylate, laurate methacrylate, butyl acrylate, myristyl methacrylate, glycidyl methacrylate or ethylene glycol dimethacrylate. 3. a preparation method of polymer porous material, is characterized in that, The solution obtained after the emulsifier is dissolved in the hydrophobic monomer is used as the oil phase; The aqueous solution containing electrolyte and initiator is used as the water phase; The oil phase and the water phase are continuously added to the twin-screw extruder, and the oil phase and the water phase are fully emulsified to form an emulsion through the shearing action of the twin-screw; After the oil phase and the water phase are fully emulsified to form an emulsion, the initiator initiates the hydrophobic monomer in the emulsion to obtain a polymer porous material with pore structure and adjustable pore structure; The mass fraction of the emulsifier in the oil phase is 5%~30%, the mass fraction of the electrolyte in the water phase is 0.5%~3%, and the oil phase and the water phase are in a volume ratio of 1:40~1 The ratio of :3 is continuously added to the twin-screw extruder, and the amount of the initiator is 1% to 3% of the mass of the hydrophobic monomer; The screw speed of the twin-screw extruder is 50-350 rpm, and the temperature of the oil phase and the water phase in the twin-screw extruder is controlled at 20-50°C. 4. the preparation method of a kind of polymer porous material according to claim 3, is characterized in that, described initiator is selected from one or both in potassium persulfate or ammonium persulfate; The electrolyte is selected from one or both of sodium chloride or calcium chloride; The emulsifier is selected from one or more of the following substances: Span80, Span60, polyglyceryl alkenyl succinate or HypermerT96; The hydrophobic monomer is selected from one or more of the following: styrene, divinylbenzene, 2-hydroxyethyl methacrylate, 2-ethylhexyl acrylate, 2-ethyl methacrylate Hexyl, lauryl acrylate, myristyl acrylate, laurate methacrylate, butyl acrylate, myristyl methacrylate, glycidyl methacrylate or ethylene glycol dimethacrylate. 5. The preparation method of a kind of polymer porous material according to claim 3, it is characterized in that, the condition that the initiator triggers the hydrophobic monomer in the emulsion to obtain the polymer porous material is: the obtained emulsion is heated to 60～90 °C.

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