DE923038C - Method for separating water from a solid resinous colloid separated from a liquid phase - Google Patents

Description

The invention relates to a method for separating water from a dimensionally stable solid resinous colloid with no evaporation of the liquid.

When creating solids, where one or more components are in the liquid phase with each other react, represents the separation of the solid matter from the liquid phase or the separation the liquid from the solid phase is a difficult operation. For example Much of the liquid, like water, is made up of a solid, like a resin, that passes through Emulsion polymerization of the monomers is formed, are separated by first doing the formed dispersion consisting of separate colloidal particles to form a pulp is precipitated, whereupon this is filtered off to form a filter cake. This in The water remaining on the filter cake can then in a known manner by means of evaporation heated air can be removed. This process is costly and time consuming. With one of these Process in which the water is evaporated out of the filter cake develops the surface of which has a crust that makes it difficult to remove the water from inside the filter cake. Another method of separating the water from the slurry is that the mass is heated in order to bring the particles contained in it to agglomerate, whereupon the to-

Collected mass filtered off and then the filter cake by evaporation of the liquid is dried. However, the dried resin obtained in this way has an unfavorable physical condition Structure, as it forms a fine, dusty powder, its handling during further processing is difficult. Drastic means are required to 'get the fine, dusty powder To compress spheres or similarly shaped bodies, as it is for the purpose of easier handling is desirable. When such agents are employed, the densified resin forms one hard, non-porous mass, and it is difficult to dissolve in most solvents. A process has now been found by means of which the water is separated from the Particles of existing mass can be separated more easily, effectively and economically can than it was previously known. The inventive method consists in that a dimensionally stable Mixture, which water and a thermoplastic, resinous, irreversibly precipitated Contains colloid, is heated in air, whose on the moist thermometer of a psychrometer read temperature of at least the agglomeration temperature of the resinous matter to remove a considerable part of the water in the liquid state. the Any remaining moisture can be added to it by means of conventional drying measures be driven out.

One such resin, which is difficult to obtain in the dry state, is that by emulsion polymerization a monomeric dienocarbon hydrogen, in particular 1,3-butadiene, and one monomeric, aromatically substituted vinyl compound, especially styrene, obtained resin. the Dispersion of this resinous copolymer becomes a slurry or paste of agglomerates precipitated or flocculated colloidal particles. But if the porridge contains too much water, in order to be dimensionally stable, it will remove the excess water at a temperature treated below the point of agglomeration of the resin until a mass is formed separate particles is obtained which has a consistency such that it is dimensionally stable Mass can be molded. This dimensionally stable mass is then so long on a Maintained temperature above the agglomeration point of the resin until no more liquid was added more to be deposited. If the sioh forming pulp is inherently dimensionally stable, d. H. forms a kind of paste, then it is not necessary to separate off excess water, and the mass is up to or ibis above the agglomeration temperature of the resin is heated in order to separate further amounts of water in the liquid state.

The process according to the invention will now be illustrated using the example of a special thermoplastic, resin-like, irreversibly precipitated colloid that has arisen by emulsion polymerization of a mixture of styrene and 1,3-butadiene. ^6s

example 1

85 parts of styrene and 0.1 part of dodecyl mercaptan were dispersed in water and polymerized with 15 parts of i, 3-butadiene, the aqueous phase consisting of 200 parts of water, 5 parts of sodium abietic acid and 0.1 part of potassium persulfate. The polymerization was carried out at 51.7 ° until the dispersion had a solids content of 32.5%, whereupon 0.5% phenyl- β- naphrhylamine was added to bring the reaction to a standstill to bring and to protect the finished product from oxidation. The dispersion was precipitated by adding a 3% solution of commercial alum in order to deposit the resin in the form of a pulp.

The pulp containing 8 to 10% solids was at 26.7 °, i.e. H. at a temperature below the agglomeration temperature of the resin, which is between 55.6 and 58.3 °, filtered on a vacuum drum filter. The thus obtained The filter cake contained 400% moisture, calculated on the completely dry substance. The filter cake was crushed by forcing it through a grid with 6.35 mm openings had a center point distance of 9.5 mm. When the resin passes through the Lattice, the resin was converted into a strand 6.35 mm in diameter, with the Lengths of the strand pieces depended on how far the mass went through each of the grid openings could be advanced without tearing off under the effect of its own weight. the The length of the strands was in general between 3.2 and 12.7 mm. The resin comminuted into such strands then fell into such a way measured amount on an endless belt that it formed a layer thereon about 10 cm thick. This 10 cm thick resin layer was then passed into a heating chamber, where the resin was left for 5 minutes was exposed for a long time to hot air, the psychrometer temperatures of which were 60 and 65.6 °. the moist air was moved downward through the resin layer at a speed of 76.25 m per Minute and with a drop in static pressure of 6.35 mm. Before heating, the moisture content was of the resin was 400% calculated on the completely dry substance, and after heating for 5 minutes the moisture content was 120%. The moisture still remaining in the resin was reduced to 0.75%, based on dry matter, removed by another 26-minute treatment with hot air, their psychrometric temperatures 38.9 and 65.6 degrees, respectively. Again, the air was down through the resin layer moves at a speed of 76.25 m per minute.

For comparison, the same resin was used with the same moisture percentage in the

Treated for the apparatus used for the experiment described above, but now using dry air, which had a temperature of 65.6 ° on the dry thermometer. After In 5 minutes only 10% of the total moisture was removed. It took 44 minutes to remove the same amount of moisture under these conditions as in that described first Attempt were removed in 5 minutes. A total of 74.5 minutes were needed to complete the Moisture content reduced to 0.75%, calculated on dry matter, while for the The operation described first only required 31 minutes.

This resulted in a time saving of 139%. if the moisture contained in the filter cake from 400% to 0.75% using the Process according to the invention is reduced, in relation to the usual, with dry hot air

ao working drying process. In addition to this saving in drying time will also be a light-colored, colored resin obtained, since the harmful, water-soluble salts during the The first 5 minutes of the drying process must be removed, since the water is a liquid and is not separated as vapor. The resin obtained has a lighter color also because it is not exposed to the drying temperature for as long as is the case with conventional drying processes necessary is.

Example 2

The experiment of Example 1 was repeated, but instead of the mixed polymer was made from 85 parts of styrene and 15 parts of 1,3-butadiene, a resinous copolymer composed of 90 parts of styrene and 10 parts of 1, 3-butadiene used. The resin was heated in a humid air, its psychrometer temperatures 68.3 and 79.4 degrees, respectively.

In this case it was possible to save 140% of drying time when drying the resin the method according to the invention can be observed, compared to the application of the usual Drying method with hot, dry air.

Polyvinyl chloride resins and copolymers of vinyl chloride and another for copolymerization suitable monomers can also be treated with advantage by the process according to the invention. The following example illustrates the treatment of a vinyl chloride copolymer according to the invention Procedure.

Example 3

95 parts of vinyl chloride were mixed with 5 parts of maleic acid diethy ester in the presence of 0.15 Share potassium persulfate until the reaction is complete. The dispersion thus obtained was precipitated with calcium chloride and the resulting slurry became at a temperature filtered from 26.7 °. This temperature is below the agglomeration temperature of the resin, which is between about 89.4 and 90.6 °. The filter cake had a moisture content of 248%, calculated on completely dry substance.

The filter cake was then kept at a temperature of 91.1 °, i.e. above the agglomeration temperature of the resin, using moist, hot air, the temperature of which was measured on the moist thermometer 91.1 °, i.e. also a temperature above the agglomeration point of the resin fraud. After the resin had been heated under these conditions for 20 minutes, 55.7% of the water had been driven off and the resin now had a moisture content of ud ⁰ / », calculated on a completely dry substance. But if the usual drying methods with hot, dry air were used, then a drying time which was 10% longer was necessary in order to remove the same amount of water.

The resin obtained in this way had a lighter color, since it was only relatively warm to the heat exposed for a short period of time and because soluble salts were removed during drying.

The same, already stated for the above examples Shortening the drying time is also observed when using the inventive method on polystyrene, copolymers of acrylonitrile and styrene and especially on the resinous ones Copolymers of 30 parts of acrylonitrile and 70 parts of styrene and on polyvinyl chloride and similar thermoplastic resins are used. The shortening of the drying time was also observed in the case of copolymers from vinyl chloride and alkyl-substituted maleic acid esters, alkyl-substituted fumaric acid esters as well as dimethyl and diethyl maleic acid and fumaric acid esters.

Any thermoplastic, resinous, precipitated, irreversible colloid can advantageously be according to the invention Procedure to be dewatered. Usually, the mixture that is formed when a polymer is precipitated Dispersion obtained cannot be dewatered by the process according to the invention, since the mixture of resin and water is too thin to retain its shape. It is first necessary to have one sufficient amount of water from the mixture at a temperature below the point of agglomeration to remove the resin so as to form a dimensionally stable mass of the resin. Under In this context, dimensionally stable is understood to be a mass that is shaped or crushed and which retains the form given to it during this process without a supporting one Device such as a hollow mold. Under certain polymerization conditions the solid content of the dispersion is sufficient to form a mass when it precipitates form, which can be dewatered by heating above the agglomeration point of the resin. In general, a precipitated mass with 20 to 30% solids is an ideal dimensionally stable one Product. Above 30 to 50% dry matter content, the ■ amount of water consumed by means of

of the method according to the invention can be deposited, more and more from.

When the dispersion has precipitated to form a slurry and the latter at a Tempe-S temperature below the agglomeration point of the resin to form a dimensionally stable If the mass is dehydrated, it is preferable to put this dimensionally stable mass in spheres or in rod-like form Shape body. This is done by

ίο the dimensionally stable mass through a grid through or through another form with the necessary openings. If circular Openings are provided, resulting in rod-shaped bodies, which are then divided into smaller ones Break sections, the length of which depends on the respective load-bearing capacity or tensile strength of the depend on the individual strand. The dimensionally stable mass can also be made by a wide, but thin one Forming device are pressed, a solid sheet-like mass is formed, which is then on a Conveyor belt and further into the heating chamber. The dimensionally stable mass can be in any other desired shape can be converted before using the inventive method is drained.

The aggregation temperature is to be understood as the temperature at which the resin particles show a tendency to melt or cake together; it is determined as follows:

i. A precipitation solution is prepared by dissolving 12 g of aluminum sulfate in 100 ecm of water; 2. one dilutes this solution with water to 2 l, whereby the temperature should not be higher than 26.7 °;

3. the precipitation solution is shaken vigorously and stirred;

4. Slowly add 300 ecm of dispersion with about 30% solids content of the substance to be tested Materials added;

5. The mixture is nitrated through a vacuum filter to remove excess liquid;

6. the wet, solid matter collected in the filter is carefully transferred to a glass plate, so that the filter cake forms a flat and continuous surface;

7. You press a thermocouple, which has an aluminum or silver plate at the connection point, into the top of the wet, solid one Mass, so that the surface temperature can be measured;

8. The mass to be tested is placed on a wet, solid substance with the thermometer inside a source of radiant or high frequency energy and heats the fabric quickly and poses the intensity of the heat source so that the surface evaporation is kept small;

9. The first appearance of exuded moisture is the temperature at that begins the agglomeration. The temperature increases continuously during the shrinkage process continue to do so until no more moisture is expelled; the temperature, at which the drainage is completed is also recorded;

10. the observed initial and final temperatures during the release of water in liquid form characterizes the temperature interval of the agglomeration.

Typical aggregation data for some thermoplastic resins

resin

Agglomeration

temperature syneresis

occurs at ⁰ C

Heat source

1. Copolymer of 27 parts 1,3-butadiene
and 73 parts of styrene

2. Copolymer of 15 parts of i, 3-butadiene
and 85 parts of styrene

3. Copolymer of 10 parts of 1,3-butadiene
and go share styrene

4. Copolymer of 95 parts of vinyl chloride
and 5 parts of maleic acid diethyl ester

The agglomeration does not usually take place at a specific temperature level, rather, they are observed within a temperature range of generally 2.8 to 5.6 ° C. Resins with an agglomeration temperature below 37.8 ° are suitable for the invention Process suitable, but not exactly practical in the

- With regard to the fact that a temperature of 37.8 ° is already normal room temperatures and it would consequently be necessary at artificially lowered temperatures to work. If moist air is used as a heating medium

36.7 to 40.0

55.6 to 58.3

61.7 to 63.9 89.4 to 90.6 250 W infrared lamp, 15.6 cm ab- i ° 5 stood from the surface of the resin

the same

the same

250 W infrared lamp, 3.8 cm from the surface of the resin

is used, resins with an aggregation temperature above 100 ° are not effective be treated as it is not possible under normal conditions, the psychrometric temperature to bring the moist air above 100 ° on the moist thermometer. When resins with an agglomeration temperature above 100 ° are to be treated, either the moist Air at elevated pressure or another heating method can be used. As an an example the use of infrared lamps can serve as another such method of heating;

however, the infrared light must be used under such conditions that the heat is jetted into the resinous mass at such a high speed that it passes through Overcomes cooling caused by evaporation. Will the heat at insufficient speed irradiated, then the resin is not heated above its agglomeration temperature, and the usual cooling due to evaporation occurs. ίο If necessary, evaporation can be avoided are made by covering the resin layer with a layer of saturated air. Another method heating consists in the application of high frequency electricity. Here, too, there must be warming be made under conditions under which the evaporation of water from the resin mass is suppressed. If polyvinyl chloride, its softening point above of 93.3 ° is to be dewatered according to the method according to the invention, it is necessary to work in a special apparatus under increased pressure, since the temperatures required above the agglomeration temperature of the polyvinyl chloride above the water vapor saturation point lie in the air.

In general, a slurry containing less than 20% solids will not retain its shape. and often it cannot even be formed. Porridges with more than 30% solids are im generally unsuitable for molding. Is the solid content of the pulp to be treated? If more than 20% substances are present, the filtering operation can be omitted. The filtering of the pulp is only necessary if the solid matter content is below the limit that it allows the mass to be given a shape.

The mass to be treated can vary in its resinous properties between hard and brittle on the one hand and foldable-pliable on the other hand, depending on the proportion of those present in it individual monomers. All copolymers resulting from the reaction of a mixture of a monomer Diene hydrocarbon with conjugated double bonds and an aryl-substituted monomer Vinyl compound emerge, the latter substance in proportions of 90 to 70 parts by weight and the monomeric diene hydrocarbon is present at 5 to 30 parts by weight (based on the Total amount of all reactive monomers present), are thermoplastic and resinous and can be treated according to the method of the invention.

Any diolefin having conjugated double bonds can be used as a resin formation component are, for example, 1,3-butadiene, isoprene, 2,3-dimethyl-i, 3-butadiene, 2-ethyl-i, 3-butadiene, 1,3-dimethyl -1,3-butadiene, 1, 3-pentadiene, 2,4-pentadiene, 3-methyl-2, 4-pentadiene, 3, 4-D1-methyl-2, 4-pentadiene, dihexadienes with straight and branched chain, the heptadienes and homologues and analogous compounds and the hydrocarbon substitution products of the aforementioned compounds. The preferred compound with conjugated double bonds used is the i, 3-butadiene.

The monomeric aryl-substituted vinyl compound of the resin can also be a monomeric aromatic Be a compound which is substituted in the α- or ^ -position with an unsaturated aliphatic radical is like styrene or the substituted styrenes, for example m-chlorostyrene, p-chlorostyrene, the isomers Dichlorostyrenes, alkylstyrenes, for example methylstyrene, isopropylstyrene, and also vinylnaphthalene etc. A particularly suitable class of these monomers is formed by the monomeric aryl-substituted ones Vinyl compounds, preferably styrene.

The service styrene resins obtained and treated by the process according to the invention are deposited in the form of a porous, dust-free, strand-like mass, the color of which varies between white and cream. The advantage of this porous and dust-free structure is particularly appreciated by paint manufacturers. It is necessary to soak the resin in an aromatic solvent such as B. toluene to dissolve before it can be converted to the base of a paint. If the resin is in the form of dust, it does not dissolve in the paint solvent, but rather has a tendency to agglomerate and form lumps caused by small amounts of the dusty resin sticking together to form a skin which isolate the inside, undissolved resin from the outside solvent. This skin must be removed by mechanical means or by continued stirring and rubbing of the solvent before the resin can be completely dissolved. The porous, dust-free spheres that are obtained by the process according to the invention quickly and completely saturate with the solvent and are dissolved in it, since the capillary cavities in the spheres suck the solvent into their interior and thus the swelling of the spheres Allow inside as well as from the outside. The resin prepared according to the processes known to date has a viscosity of 20 to 25 seconds for a 20 ° / o solution in xylene at 20 ⁰ for his caused by trituration dissolution. In contrast, the resin produced by the process according to the invention showed a viscosity between 30 and 38 seconds.

Various changes and modifications can be made without changing the area to leave the inventive idea.

Claims (5)

Patent claims: i. Method for separating water from iao one containing water and a thermoplastic resinous irreversibly precipitated colloid unrestricted dimensionally stable mass, characterized in that the mixture is heated in an air whose on wet thermometer of a pshrometer read temperature of at least the agglomeration temperature of the resin equals, whereupon the remaining moisture through Usual drying process is driven out. 2. The method according to claim i, characterized in that that the mass is at a temperature below its point of agglomeration and prior to agglomeration and separating the water into a large number of smaller parts is formed. 3. The method according to claim 1 or 2, characterized characterized in that a resinous colloid is used for treatment, which by the in aqueous Emulsion polymerization of a mixture of a monomeric diene compound with conjugated double bonds and a monomeric aryl-substituted vinyl compound is generated. 4. The method according to claim 3, characterized in that a resinous colloid is used obtained by copolymerization of i, 3-butadiene and styrene, in particular by copolymerization of a mixture of 10 to 20, preferably 10 to 15 parts of i, 3-butadiene and 90 to 80, preferably 90 to 85 parts of styrene. 5. The method according to claim 1 or 2, characterized in that a resinous Colloid comes for treatment, which takes place in the aqueous emulsion polymerization of vinyl chloride or a mixture of vinyl chloride and dialkyl maleic acid ester or dialkyl fumaric acid ester is produced. © 9585 1.55