CA1105632A - Process for making polymer solutions - Google Patents
Process for making polymer solutionsInfo
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- CA1105632A CA1105632A CA273,680A CA273680A CA1105632A CA 1105632 A CA1105632 A CA 1105632A CA 273680 A CA273680 A CA 273680A CA 1105632 A CA1105632 A CA 1105632A
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- polymer
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- aqueous medium
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J3/00—Processes of treating or compounding macromolecular substances
- C08J3/02—Making solutions, dispersions, lattices or gels by other methods than by solution, emulsion or suspension polymerisation techniques
- C08J3/09—Making solutions, dispersions, lattices or gels by other methods than by solution, emulsion or suspension polymerisation techniques in organic liquids
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- Dispersion Chemistry (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Processes Of Treating Macromolecular Substances (AREA)
Abstract
PROCESS FOR MAKING POLYMER SOLUTIONS
Abstract of the Disclosure A process is provided for the preparation of a solution of a polymer in a hydrocarbyl solvent which process comprises separating a polymer from a dispersion of small sized particles thereof in an aqueous medium, adding a hydrocarbyl solvent to the separated polymer and transferring the solvent-polymer mixture to a dissolving section wherein the mixture is agitated to yield a solution of said polymer. Such polymer solutions may be used to produce a latex, a caulking or sealing compound or for chemical modification.
Abstract of the Disclosure A process is provided for the preparation of a solution of a polymer in a hydrocarbyl solvent which process comprises separating a polymer from a dispersion of small sized particles thereof in an aqueous medium, adding a hydrocarbyl solvent to the separated polymer and transferring the solvent-polymer mixture to a dissolving section wherein the mixture is agitated to yield a solution of said polymer. Such polymer solutions may be used to produce a latex, a caulking or sealing compound or for chemical modification.
Description
5~i3;2 This inven~ion is direc~ed to a novel process for preparing a solution of a polymer in a hyclrocarbyl solvent.
Conventional methods for dissolving a polymer in a solvent usually require the rubber to be as ~mall pieces, normally generated by chopping or grinding, in a suitable vessel to which is added the solvent. This is then subjected to agitation and usually heated somewhat in order to reduce the time necessary to cause the polymer to go lnto solution. In spite of this, it is a costly and time-consuming operation.
There is also known, in the field of butyl rubbers, a process whereby a slurry of butyl rubber and unreacted monomers in methyl chloride is passed from the reactor, wherein the butyl rubber is formed, to a flash tank wherein the slurry is contacted with a hot hydro-carbon which is a solvent for the polymer, the rubber being converted into a solution in the hydrocarbon and the methyl chloride and unreac~ed monomers vaporized and removed for purification and re-use.
We have now discovered a novel process for preparing a solutlon of a polymer in a hydrocarbyl solvent wherein a water wet small particle size polymer crumb is separated from the bulk of the water, a hydrocarbyl solvent is added to the separated polymer crumb which, on being agitated at slightly eleva~ed temperatures, rapidly yields a solution of the polymer in the hydrocarbyl solvent.
According to the present invention, there îs provided a process for preparing a solution of a polymer in a hydrocarbyl solvent which comprises subjecting a
Conventional methods for dissolving a polymer in a solvent usually require the rubber to be as ~mall pieces, normally generated by chopping or grinding, in a suitable vessel to which is added the solvent. This is then subjected to agitation and usually heated somewhat in order to reduce the time necessary to cause the polymer to go lnto solution. In spite of this, it is a costly and time-consuming operation.
There is also known, in the field of butyl rubbers, a process whereby a slurry of butyl rubber and unreacted monomers in methyl chloride is passed from the reactor, wherein the butyl rubber is formed, to a flash tank wherein the slurry is contacted with a hot hydro-carbon which is a solvent for the polymer, the rubber being converted into a solution in the hydrocarbon and the methyl chloride and unreac~ed monomers vaporized and removed for purification and re-use.
We have now discovered a novel process for preparing a solutlon of a polymer in a hydrocarbyl solvent wherein a water wet small particle size polymer crumb is separated from the bulk of the water, a hydrocarbyl solvent is added to the separated polymer crumb which, on being agitated at slightly eleva~ed temperatures, rapidly yields a solution of the polymer in the hydrocarbyl solvent.
According to the present invention, there îs provided a process for preparing a solution of a polymer in a hydrocarbyl solvent which comprises subjecting a
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polymer in the form of small sized par~icles dispersed in an aqueous medium to a separation process whereby the bulk of the aqueous medium is removed, the still wet small particles of polymer are removed, a hydrocarbyl solvent is added thereto and mixed therewith and the mi~ture is transferred to a dissolving section wherein the mixture is agitated, optionally while being heated to a slightly elevated temperature, to rapidly yield a solution of said polymer in said hydrocarbyl solvent, which solution also contains dispersed water.
One oE the problems associated with the prepara-tion o~ polymer solutions is that it is normally necessary to use polymer which is pure, dry and of small particle size. The polymer is normally in a compacted form and consequently has a well formed surEace for contact with the solvent. The small particle size is frequently achieved by chopping or grinding of large masses of previously dried polymer or occasionally by a finishing process which yields essentially dry par~icles.
Generally, the surface area of the polymer particles is small compared to their volume. A solvent ac~s on a polymer which is soluble therein at the surface of the polymer and the time required to dissolve the polymer depends upon the surface area available for contact with the solvent. With the present process no chopping or grinding is necessary thereby eliminating a high energy consuming step, the sur~ace of the polymer particles is lrregular, exhibiting a very high sur~ace area and the polymer particles have a low bulk density (i.e. are not compacted). Further, the polymer does not need to be .~
dried, a further energy saving ~ac~or. The polymer has a high surface area for contact with the solvent which leads to a high rate of dissolvin~ of the polymer in the solvent. Further, the present process is not a~ected by the presence of water on the sur~ace o~ t~e polymer particles.
In the present process, suitable polymers are those that can be obtained as small sized particles dis-persed in an aqueous medium. Such polymers include thermoplastic and rubbery polymers. Thermoplastics include the poly-alpha-C2-C6-olefin homo- and copolymers, e.g. polyethylene and polybutylene, polyvinyl chloride, polyvinylidene chloride, copolymers containing a major proportion of vinyl chlorlde or vinylidene chloride, and polystyrene. Rubbery polymers include the styrene-conjugated diolefin polymers, e.g.
styrene-butadiene rubbers, the poly C4-C6 conjugated diolefins, e.~. polybutadiene, ethylene-propylene-diene monomer polymers~ polyisobutylene and the iso~utylene-C~-C6 conjugated dioleEin copolymers, e.g.
isobutylene-isoprene copolymers. All such polymers must be essentially soluble in a hydrocarbyl solvent.
Generally, the suitable polymers are either manufactured in an aqueous medium or are recovered in an aqueous medium. For example, in a Ziegler-type process Eor the manuEacture of high density polyethylene the polymer slurry, after catalyst removal, may be contacted with an aqueous medium, such as water to provide a dispersion of polymer particles in the aqueous medium. In a suspension process for the manufacture oE polyvinyl '~
rs~,3 chloride, the aqueous suspension, a~ter dumping from ~he reactor and stripping of residual monomer may be coagulated to provide a dispersion of polyvinyl chloride particles in an aqueous medium, especially water. In the emulsion polymerization of styrene ancl butadiene the latex from the reactors is stripped o~ residual monomers and then coagulated to yield a dispersion of styrene-butadiene polymer particles in an aqueous medium. In the manu-facture of butyl rubber, the slurry of butyl polymer and unreacted monomers in methyl chloride is contacted with an aqueous medium and subjected to stripping to remove unreacted monomers and methyl chloride, yielding a dis-persion o~ butyl polymer particles ln an aqueous medium.
Such aforementioned dispersions of polymer particles in an aqueous medium, also frequently referred to as slurries, may contain from about 2 to about 25 weight per cent of polymer, preferably from about 4 to about 20 weight per cent, and most preferably from about 4 to about 10 weight per cent~ o~ polymer in the aqueous medium. The size of the particles o~ polymer is up to about 2.5 cm, preferably up to about 1.5 cm, as the larges-t dimension. Under no circumstances does the term small sized particles of polymer dispersed in an aqueous medium include a latex.
In the present process, the slurry o~ small sized polymer particles in an aqueous medium is subjected to a separation process wherein the bulk o~ the aqueous medium is removed, yielding small sized polymer particles usually having a sur~ace coating of the aqueous medium. The amount of the aqueous medium associated wi-th the polymer par-ticles aEter the separation may be Erom about 5 to 1 ~ '
, .
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polymer in the form of small sized par~icles dispersed in an aqueous medium to a separation process whereby the bulk of the aqueous medium is removed, the still wet small particles of polymer are removed, a hydrocarbyl solvent is added thereto and mixed therewith and the mi~ture is transferred to a dissolving section wherein the mixture is agitated, optionally while being heated to a slightly elevated temperature, to rapidly yield a solution of said polymer in said hydrocarbyl solvent, which solution also contains dispersed water.
One oE the problems associated with the prepara-tion o~ polymer solutions is that it is normally necessary to use polymer which is pure, dry and of small particle size. The polymer is normally in a compacted form and consequently has a well formed surEace for contact with the solvent. The small particle size is frequently achieved by chopping or grinding of large masses of previously dried polymer or occasionally by a finishing process which yields essentially dry par~icles.
Generally, the surface area of the polymer particles is small compared to their volume. A solvent ac~s on a polymer which is soluble therein at the surface of the polymer and the time required to dissolve the polymer depends upon the surface area available for contact with the solvent. With the present process no chopping or grinding is necessary thereby eliminating a high energy consuming step, the sur~ace of the polymer particles is lrregular, exhibiting a very high sur~ace area and the polymer particles have a low bulk density (i.e. are not compacted). Further, the polymer does not need to be .~
dried, a further energy saving ~ac~or. The polymer has a high surface area for contact with the solvent which leads to a high rate of dissolvin~ of the polymer in the solvent. Further, the present process is not a~ected by the presence of water on the sur~ace o~ t~e polymer particles.
In the present process, suitable polymers are those that can be obtained as small sized particles dis-persed in an aqueous medium. Such polymers include thermoplastic and rubbery polymers. Thermoplastics include the poly-alpha-C2-C6-olefin homo- and copolymers, e.g. polyethylene and polybutylene, polyvinyl chloride, polyvinylidene chloride, copolymers containing a major proportion of vinyl chlorlde or vinylidene chloride, and polystyrene. Rubbery polymers include the styrene-conjugated diolefin polymers, e.g.
styrene-butadiene rubbers, the poly C4-C6 conjugated diolefins, e.~. polybutadiene, ethylene-propylene-diene monomer polymers~ polyisobutylene and the iso~utylene-C~-C6 conjugated dioleEin copolymers, e.g.
isobutylene-isoprene copolymers. All such polymers must be essentially soluble in a hydrocarbyl solvent.
Generally, the suitable polymers are either manufactured in an aqueous medium or are recovered in an aqueous medium. For example, in a Ziegler-type process Eor the manuEacture of high density polyethylene the polymer slurry, after catalyst removal, may be contacted with an aqueous medium, such as water to provide a dispersion of polymer particles in the aqueous medium. In a suspension process for the manufacture oE polyvinyl '~
rs~,3 chloride, the aqueous suspension, a~ter dumping from ~he reactor and stripping of residual monomer may be coagulated to provide a dispersion of polyvinyl chloride particles in an aqueous medium, especially water. In the emulsion polymerization of styrene ancl butadiene the latex from the reactors is stripped o~ residual monomers and then coagulated to yield a dispersion of styrene-butadiene polymer particles in an aqueous medium. In the manu-facture of butyl rubber, the slurry of butyl polymer and unreacted monomers in methyl chloride is contacted with an aqueous medium and subjected to stripping to remove unreacted monomers and methyl chloride, yielding a dis-persion o~ butyl polymer particles ln an aqueous medium.
Such aforementioned dispersions of polymer particles in an aqueous medium, also frequently referred to as slurries, may contain from about 2 to about 25 weight per cent of polymer, preferably from about 4 to about 20 weight per cent, and most preferably from about 4 to about 10 weight per cent~ o~ polymer in the aqueous medium. The size of the particles o~ polymer is up to about 2.5 cm, preferably up to about 1.5 cm, as the larges-t dimension. Under no circumstances does the term small sized particles of polymer dispersed in an aqueous medium include a latex.
In the present process, the slurry o~ small sized polymer particles in an aqueous medium is subjected to a separation process wherein the bulk o~ the aqueous medium is removed, yielding small sized polymer particles usually having a sur~ace coating of the aqueous medium. The amount of the aqueous medium associated wi-th the polymer par-ticles aEter the separation may be Erom about 5 to 1 ~ '
3~
about 60 weight per cent based on polymer plus aqueous medium. Preferably, the amount of water may be from about 20 to about 60 weight per cent and most preferably from about 40 to about 6~ weight per cent. Means of achieving such a separation are well known the ar~ and include various forms of density gradient separation, filtering and passage over separatory screens so that the aqueous phase is separated. Particularly useful are the stationary or vibrating screen separators whereby still wet polymer particles are retained on top of the screens, which are preferably inclined at an angle to the horizontal, and the aqueous phase drains away through the screens.
The .so-separated wet polymer particles are then re~oved and a h~drocarbyl solvent is added and mixed with the polymer particles. A simple method of achieving this is to remove the wet polymer particles from the separation s~age and to transfer them to a receiving vessel and to add a hydrocar~yl solvent simultaneously to the polymer particles in the vessel. It is preferred that the residence time in the receiving v0ssel be short enough that dissolving of t~e polymer does not take place to a significant extent, for example, less than about 2 weight per cent of the polymer is dissolved in the solvent~
preferably less than 0.5 weight per cent is dissolved. It is preferred that the hydrocarbyl solvent act as a carrier to transfer the polymer to the next stage in the process.
The amount of solvent fed to the receiving vessel will normally be from about 25 to about 100 volume per cent of 0 the total required to make the polymer solution. Pre-~ ~5~3~
ferably the amount of solvent is from about 40 to about 75 volume per cent of the total required.
Suitable hydrocarbyl solvents are those which will dissolve the particular polymer. Thus for the rubbery polymers, suitable solvents include the C5-C10 alkanes and the C6-C8 aromatic hydrocarbons, typical examples being hexane and toluene respectively. For vinyl chloride type polymers suitable solvents include tetra-hydrofuran and cyclohexanone and for vinylidene chloride polymers suitable solvents include tetrahydrofuran and 1,4-dioxane.
In the present process, the ~ixture of polymer particles and solvent is then transferred from the receiving vessel by means well known in the art, prefer-ably by means o a screw type pump, to the dlssolving section. The dissolving section comprises one or more vessels equipped with agitators and optionally with temperature control means. Polymer particles wetted with a solvent are well known as being sticky and adhere `
readily to each other and to any available surEace. Thus, it is desirable in the dlssolving section not to have internal heat exchange colls Eor control of the tempera-ture; rather, a jacketed vessel having external hea-ting coils is more suitable. Additional heat can also be provided by supplying heated solvent. Thus a stream o solvent which has been heated to a suitable temperature o from about 35 to about 100C may be introduced along with the mixture of polymer particles and solvent or directly to the dissolving section. The amount of heated solvent so introduced may be from about 0 to about 75 ~ `563;~
volume per cent of the total required to make the polymer solu-tion, pre~erably Erom about 25 to about 60 volume per centO The temperature in the dissolving section is dependent on the nature of the polymer-solvent system.
For example, for polyvinyl chloride-1,4-dioxane, the temperature will usually be between about 50 and 100C. For styrene-butadiene polymer and hexane or ~or isobutylene-C4-C6 conjugated diole-fin polymer and hexane, the temperature will usually be between about 20 and 60C. The temperature to which heated solvent is actually heated is readily ascertained and depends on the temperature to be achieved in the dissolving section and on the volume per cent oE the solvent beirlg heated.
For e~ample, for the styrene-butadiene polymer hexane system or Eor the isobutylene-C4~C6 conjugated diole~in polymer hexane system, the original mix~ure o~
polymer particles and hexane fed to the dissolving section may be at a temperature of about 15 to about 40C, the heated hexane may constitute about 25 to about 60 volume per cent of the total used and may be at a tempera-ture o~ about 35 ~ 70C and the temperature in the dissolving section may be about 35 - 60C.
~lternatively, the hexane added to the polymer particles in the receiving vessel may be at a temperature of abou~
10 to about 50C, no further hexane is added and thR
~ temperature in the dissolving section may be maintained at - abou-t 30 to about 50C.
The dissolving section comprises one or more vessels or one vessel divided into two or more connected compartments. The vessels are equipped with agitators and _ ~ _ ,. ,.~ .
~ 5~
may9 depending on the temperature and pressure conditions to be found therein, be pressure vessels capable of operation at pressures of l to 30 psig, preferably 1 to 15 psig. In one preferred system two vessels in series are used, each being equipped with an agit:ator and the material flow is such that essentially no shor~-circuiting of solvent can occur, using design means well known in the art. In another preferred system, a single vessel is used, the vessel being sub-divided into two or more, and up to six, connected compartments, the connection being by direct overflow or underflow from one compartment to the next, each compart~ent bei.ng connected to the next alternately by an over~low at the top of the vessel or an underflow at the bottom of the vessel. Each compartment is equipped with an agitator. Such a compartmented vessel may be in a horizontal or ver~ical position, a horizon~al vessel being preferred.
The concentration of polymer in the solution obtained from ~he dissolving section is from about 2 to about 25 weight per cent 7 preferably from about 10 to about 20 weight per cent and most preferably Erom about 12 to about 18 weight per cent.
The over~low ~rom the dissolving sectiGn will normally be to a storage vessel, for feeding to a sub-sequent operation which may be the production of a latex, the production of a caulking or sealing compound or for a chemical modification process.
In an example of the process o-f this invention, a butyl rubber slurry in water is fed to a separatory screen which is inclined at an angle of about 30 to the _ g _ i3~
horizontal. The butyl rubber is a copoly~er oE about 98.
moles of isobutylene and about 1.~ moles of isoprene and has a Mooney (ML-12 at 125C) of 50. The butyl rubber slurry contains about 5 weight per cent of butyl rubber in water and is normally at a temperature of about 50 to about 70C, in this example about 60C. The majority of the water is separated on the separatory screen by passing through the screen and the wet bu-~yl rubber which comprises about 50 weight per cent butyl rubber and about 50 weight per cent water is removed from the sur-face of the screen by gravity and is passed into an open receiving vessel o about 1,000 U.S. gallon capacity. The rate oE
passage of wet butyl rubber to the receiving vessel is about 8,000 pounds per hour, i.e. about 4,000 pounds per hour dry rubber basis and typically may range Erom about 2,000 to about 20,000 pounds per hour. To this vessel is also fed a supply of hexane at such a rate for this example as to be 50% of that necessary to prod~lce the rubber solution. The he~ane is at a temperature oE about Zl to 22C. The concentra-tion of rubber in the finally produced solution is to be about 14 wei~h~ per cent: thus the hexane is added to the receiving vessel at about 2,200 U.S. gallons -per hour. The residence time in the receiving vessel is very short, only being from about 10 seconds ~o about 2 minutes. The mixture of butyl rubber and hexane is removed from the bottom of the receiving vessel by means of a suitable pump. An especially preferred pump is one wherein a single screw rotor operates within an elastomeric stationary female sleeve, such as a Moyno (Trademark) pump. The butyl rubber/hexane ~S~i3~
mixture is transferred to a dissolving tank, which is a horizontal dissolving tank having four essentiall~
separated compartments. Each compartment is equipped with an agitator. The butyl rubber/hexane mixture is fed through an inlet at the bottom half of the end wall of the tank directly into the Eirst compartment which is separated from the second compartment by means of a vertical baffle, attached to the bottom of the interior of the tank and being about two-thirds of the height of the tank. The second compartment is separated -from the third compartment by a vertical bafle, attached to the top of the interior of the tank and reaching down abou~
two-thirds of the height of the tank. The third compart-ment is, in turn, separated from the ourth and final compartment by a vertical ba~fle, attached to the ~ottom of the interior of the tank and being about two-thirds of the height of the tank. The fourth compartment is terminated by a final vertical baffle attached to the top of the interior of the tank and reaching down about two-thirds oE the height o~ the tank, this final baffle being located only a short distance from the end wall of the tank and the final product from the dissolving tank is removed via an outlet in the top half of this end wall.
The total volume of the tank is about 40,000 U.S. gallons and each compartment is about one quarter of the total ; volume. A stream of hot hexane is also fed into -the firs-t compartment of the dissolving tank. The temperature of the hexane is about 50C and the volume of hexane is that necessary to produce the inal desired concentration of the rubber in the solution and in this example is about '~
~ 3 ~
50% of the total necessary hexane and is added at a rate of about 2,200 U.S. gallons per hour. No additional heat is put into the dissolving tank and the temperature oE the solution removed from the last compartment is about 45C. The product removed rom the outlet line Erom ~he fourth compartment of the dissolving tank is a solution of butyl rubber in hexane containing about 14 weigh~ per cent of butyl rubber, and is transferred to a storage vessel from which it may be used for a chemical modifica~ion, for the preparation of a caulking or sealing compound or for the preparation of a butyl rubber latex. Any excess water which may separate from -the solution may be removed by draining either Erom the fourth compartment oE the dis-solving tank or from the storage vessel. The amount of water present in the solution may be from about 2 to about 25 weight per cent, mos-t preferably from about 10 to about 20 weight per cent and in this example is about 12 to 14 weight per cent.
about 60 weight per cent based on polymer plus aqueous medium. Preferably, the amount of water may be from about 20 to about 60 weight per cent and most preferably from about 40 to about 6~ weight per cent. Means of achieving such a separation are well known the ar~ and include various forms of density gradient separation, filtering and passage over separatory screens so that the aqueous phase is separated. Particularly useful are the stationary or vibrating screen separators whereby still wet polymer particles are retained on top of the screens, which are preferably inclined at an angle to the horizontal, and the aqueous phase drains away through the screens.
The .so-separated wet polymer particles are then re~oved and a h~drocarbyl solvent is added and mixed with the polymer particles. A simple method of achieving this is to remove the wet polymer particles from the separation s~age and to transfer them to a receiving vessel and to add a hydrocar~yl solvent simultaneously to the polymer particles in the vessel. It is preferred that the residence time in the receiving v0ssel be short enough that dissolving of t~e polymer does not take place to a significant extent, for example, less than about 2 weight per cent of the polymer is dissolved in the solvent~
preferably less than 0.5 weight per cent is dissolved. It is preferred that the hydrocarbyl solvent act as a carrier to transfer the polymer to the next stage in the process.
The amount of solvent fed to the receiving vessel will normally be from about 25 to about 100 volume per cent of 0 the total required to make the polymer solution. Pre-~ ~5~3~
ferably the amount of solvent is from about 40 to about 75 volume per cent of the total required.
Suitable hydrocarbyl solvents are those which will dissolve the particular polymer. Thus for the rubbery polymers, suitable solvents include the C5-C10 alkanes and the C6-C8 aromatic hydrocarbons, typical examples being hexane and toluene respectively. For vinyl chloride type polymers suitable solvents include tetra-hydrofuran and cyclohexanone and for vinylidene chloride polymers suitable solvents include tetrahydrofuran and 1,4-dioxane.
In the present process, the ~ixture of polymer particles and solvent is then transferred from the receiving vessel by means well known in the art, prefer-ably by means o a screw type pump, to the dlssolving section. The dissolving section comprises one or more vessels equipped with agitators and optionally with temperature control means. Polymer particles wetted with a solvent are well known as being sticky and adhere `
readily to each other and to any available surEace. Thus, it is desirable in the dlssolving section not to have internal heat exchange colls Eor control of the tempera-ture; rather, a jacketed vessel having external hea-ting coils is more suitable. Additional heat can also be provided by supplying heated solvent. Thus a stream o solvent which has been heated to a suitable temperature o from about 35 to about 100C may be introduced along with the mixture of polymer particles and solvent or directly to the dissolving section. The amount of heated solvent so introduced may be from about 0 to about 75 ~ `563;~
volume per cent of the total required to make the polymer solu-tion, pre~erably Erom about 25 to about 60 volume per centO The temperature in the dissolving section is dependent on the nature of the polymer-solvent system.
For example, for polyvinyl chloride-1,4-dioxane, the temperature will usually be between about 50 and 100C. For styrene-butadiene polymer and hexane or ~or isobutylene-C4-C6 conjugated diole-fin polymer and hexane, the temperature will usually be between about 20 and 60C. The temperature to which heated solvent is actually heated is readily ascertained and depends on the temperature to be achieved in the dissolving section and on the volume per cent oE the solvent beirlg heated.
For e~ample, for the styrene-butadiene polymer hexane system or Eor the isobutylene-C4~C6 conjugated diole~in polymer hexane system, the original mix~ure o~
polymer particles and hexane fed to the dissolving section may be at a temperature of about 15 to about 40C, the heated hexane may constitute about 25 to about 60 volume per cent of the total used and may be at a tempera-ture o~ about 35 ~ 70C and the temperature in the dissolving section may be about 35 - 60C.
~lternatively, the hexane added to the polymer particles in the receiving vessel may be at a temperature of abou~
10 to about 50C, no further hexane is added and thR
~ temperature in the dissolving section may be maintained at - abou-t 30 to about 50C.
The dissolving section comprises one or more vessels or one vessel divided into two or more connected compartments. The vessels are equipped with agitators and _ ~ _ ,. ,.~ .
~ 5~
may9 depending on the temperature and pressure conditions to be found therein, be pressure vessels capable of operation at pressures of l to 30 psig, preferably 1 to 15 psig. In one preferred system two vessels in series are used, each being equipped with an agit:ator and the material flow is such that essentially no shor~-circuiting of solvent can occur, using design means well known in the art. In another preferred system, a single vessel is used, the vessel being sub-divided into two or more, and up to six, connected compartments, the connection being by direct overflow or underflow from one compartment to the next, each compart~ent bei.ng connected to the next alternately by an over~low at the top of the vessel or an underflow at the bottom of the vessel. Each compartment is equipped with an agitator. Such a compartmented vessel may be in a horizontal or ver~ical position, a horizon~al vessel being preferred.
The concentration of polymer in the solution obtained from ~he dissolving section is from about 2 to about 25 weight per cent 7 preferably from about 10 to about 20 weight per cent and most preferably Erom about 12 to about 18 weight per cent.
The over~low ~rom the dissolving sectiGn will normally be to a storage vessel, for feeding to a sub-sequent operation which may be the production of a latex, the production of a caulking or sealing compound or for a chemical modification process.
In an example of the process o-f this invention, a butyl rubber slurry in water is fed to a separatory screen which is inclined at an angle of about 30 to the _ g _ i3~
horizontal. The butyl rubber is a copoly~er oE about 98.
moles of isobutylene and about 1.~ moles of isoprene and has a Mooney (ML-12 at 125C) of 50. The butyl rubber slurry contains about 5 weight per cent of butyl rubber in water and is normally at a temperature of about 50 to about 70C, in this example about 60C. The majority of the water is separated on the separatory screen by passing through the screen and the wet bu-~yl rubber which comprises about 50 weight per cent butyl rubber and about 50 weight per cent water is removed from the sur-face of the screen by gravity and is passed into an open receiving vessel o about 1,000 U.S. gallon capacity. The rate oE
passage of wet butyl rubber to the receiving vessel is about 8,000 pounds per hour, i.e. about 4,000 pounds per hour dry rubber basis and typically may range Erom about 2,000 to about 20,000 pounds per hour. To this vessel is also fed a supply of hexane at such a rate for this example as to be 50% of that necessary to prod~lce the rubber solution. The he~ane is at a temperature oE about Zl to 22C. The concentra-tion of rubber in the finally produced solution is to be about 14 wei~h~ per cent: thus the hexane is added to the receiving vessel at about 2,200 U.S. gallons -per hour. The residence time in the receiving vessel is very short, only being from about 10 seconds ~o about 2 minutes. The mixture of butyl rubber and hexane is removed from the bottom of the receiving vessel by means of a suitable pump. An especially preferred pump is one wherein a single screw rotor operates within an elastomeric stationary female sleeve, such as a Moyno (Trademark) pump. The butyl rubber/hexane ~S~i3~
mixture is transferred to a dissolving tank, which is a horizontal dissolving tank having four essentiall~
separated compartments. Each compartment is equipped with an agitator. The butyl rubber/hexane mixture is fed through an inlet at the bottom half of the end wall of the tank directly into the Eirst compartment which is separated from the second compartment by means of a vertical baffle, attached to the bottom of the interior of the tank and being about two-thirds of the height of the tank. The second compartment is separated -from the third compartment by a vertical bafle, attached to the top of the interior of the tank and reaching down abou~
two-thirds of the height of the tank. The third compart-ment is, in turn, separated from the ourth and final compartment by a vertical ba~fle, attached to the ~ottom of the interior of the tank and being about two-thirds of the height of the tank. The fourth compartment is terminated by a final vertical baffle attached to the top of the interior of the tank and reaching down about two-thirds oE the height o~ the tank, this final baffle being located only a short distance from the end wall of the tank and the final product from the dissolving tank is removed via an outlet in the top half of this end wall.
The total volume of the tank is about 40,000 U.S. gallons and each compartment is about one quarter of the total ; volume. A stream of hot hexane is also fed into -the firs-t compartment of the dissolving tank. The temperature of the hexane is about 50C and the volume of hexane is that necessary to produce the inal desired concentration of the rubber in the solution and in this example is about '~
~ 3 ~
50% of the total necessary hexane and is added at a rate of about 2,200 U.S. gallons per hour. No additional heat is put into the dissolving tank and the temperature oE the solution removed from the last compartment is about 45C. The product removed rom the outlet line Erom ~he fourth compartment of the dissolving tank is a solution of butyl rubber in hexane containing about 14 weigh~ per cent of butyl rubber, and is transferred to a storage vessel from which it may be used for a chemical modifica~ion, for the preparation of a caulking or sealing compound or for the preparation of a butyl rubber latex. Any excess water which may separate from -the solution may be removed by draining either Erom the fourth compartment oE the dis-solving tank or from the storage vessel. The amount of water present in the solution may be from about 2 to about 25 weight per cent, mos-t preferably from about 10 to about 20 weight per cent and in this example is about 12 to 14 weight per cent.
Claims (15)
1. A process for preparing a solution of a polymer in a hydrocarbyl solvent which comprises subjecting a polymer in the form of a slurry in an aqueous medium of small sized polymer particles of up to about 2.5 cm as the largest dimension to a separation process whereby the bulk of the aqueous medium is removed, the still wet particles of polymer are removed from the separation process and transferred to a receiving vessel and hydrocarbyl solvent is simultaneously added to said receiving vessel, the residence time of the mixture in the receiving vessel being short enough that less than about 2 weight per cent of the polymer dissolves in the solvent, the mixture is transferred from said receiving vessel to a dissolving section wherein the mixture is agitated, optionally while being heated to a slightly elevated tempera-ture, to rapidly yield a solution of said polymer in said hydrocarbyl solvent, which solution also contains dispersed water.
2. The process of Claim 1 wherein the polymer in the slurry in the aqueous medium forms from about 2 to about 25 weight per cent of such slurry.
3. The process of Claim 1 wherein the separation process comprises passage over a stationary or vibrating screen separator yielding still wet particles of polymer retained on top of the screen and the aqueous medium drains away through the screens.
4. The process of Claim 2 or 3 wherein the still wet particles of polymer contain from about 5 to about 60 weight per cent of the aqueous medium based on polymer plus aqueous medium.
5. The process of Claim 3 wherein the dissolving section comprises one or more vessels equipped with agitators.
6. The process of Claim 5 wherein the dissolving section contains two vessels connected in series.
7. The process of Claim 5 wherein the dissolving section is a single vessel subdivided into two to six connected compartments, each compartment being equipped with an agitator.
8. The process of Claim 7 wherein each compartment is connected to the next by direct overflow or underflow from one compartment to the next.
9. The process of Claim 5 wherein the solution from said dissolving section contains from about 2 to about 25 weight per cent of polymer in said solution.
10. The process of Claim 9 wherein the solution also contains from about 2 to about 25 weight per cent of water present in the solution.
11. The process of Claim 3 wherein the amount of solvent added to the receiving means is from about 25 to about 100 volume per cent of the total required to make the polymer solution.
12. The process of Claim 11 wherein from about 0 to about 75 volume per cent of the hydrocarbyl solvent required to make the polymer solution is added to the dissolving section and is at a temperature of about 35° to about 100°C.
13. The process of Claims 1, 3 or 7 wherein the polymer is a thermoplastic polymer selected from poly-alpha-C2-C6-olefin polymers, polyvinyl chloride, polyvinylidene chloride and copolymers containing a major proportion of vinyl chloride or vinylidene chloride.
14. The process of Claims 1, 3 or 7 wherein the polymer is a rubbery polymer selected from styrene-conjugated diolefin polymers, poly C4-C6 conjugated diolefins, ethylene-propylene-diene monomer polymers, polyisobutylene and isobutylene - C4-C6 conjugated diolefin polymers.
15. The process of Claims 1, 3 or 7 wherein the polymer is one of a styrene-butadiene polymer or an isobutylene-C4-C6 conjugated diolefin polymer and the hydrocarbyl solvent is hexane.
Priority Applications (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA273,680A CA1105632A (en) | 1977-03-10 | 1977-03-10 | Process for making polymer solutions |
| BE185775A BE864702A (en) | 1977-03-10 | 1978-03-09 | PROCESS FOR PRODUCING A POLYMER SOLUTION |
| IT67509/78A IT1111612B (en) | 1977-03-10 | 1978-03-09 | PROCEDURE FOR THE PREPARATION OF POLYMER SOLUTIONS |
| FR7806815A FR2383210B1 (en) | 1977-03-10 | 1978-03-09 | PROCESS FOR PRODUCING POLYMER SOLUTION |
| JP2716778A JPS53112941A (en) | 1977-03-10 | 1978-03-09 | Production of polymer solution |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA273,680A CA1105632A (en) | 1977-03-10 | 1977-03-10 | Process for making polymer solutions |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1105632A true CA1105632A (en) | 1981-07-21 |
Family
ID=4108123
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA273,680A Expired CA1105632A (en) | 1977-03-10 | 1977-03-10 | Process for making polymer solutions |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JPS53112941A (en) |
| BE (1) | BE864702A (en) |
| CA (1) | CA1105632A (en) |
| FR (1) | FR2383210B1 (en) |
| IT (1) | IT1111612B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4469826A (en) * | 1983-06-02 | 1984-09-04 | Sun Chemical Corporation | Process for the production of dispersions of polymers in non-aqueous vehicles |
| EP2313441B1 (en) * | 2008-08-05 | 2012-10-03 | Dow Global Technologies LLC | Solvent transfer process for organic polymers |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL216461A (en) * | 1956-04-18 | |||
| GB1022710A (en) * | 1964-02-17 | 1966-03-16 | Columbian Carbon | Method of dissolving eltasomers |
| FR1428643A (en) * | 1964-02-17 | 1966-02-18 | Columbian Carbon | Process for dissolving elastomers in organic solvents |
| FR1444438A (en) * | 1964-08-01 | 1966-07-01 | Basf Ag | Process for the preparation of polymer solutions |
| FR1444478A (en) * | 1964-08-08 | 1966-07-01 | Basf Ag | Process for preparing anhydrous solutions of polymers |
-
1977
- 1977-03-10 CA CA273,680A patent/CA1105632A/en not_active Expired
-
1978
- 1978-03-09 JP JP2716778A patent/JPS53112941A/en active Pending
- 1978-03-09 BE BE185775A patent/BE864702A/en not_active IP Right Cessation
- 1978-03-09 FR FR7806815A patent/FR2383210B1/en not_active Expired
- 1978-03-09 IT IT67509/78A patent/IT1111612B/en active
Also Published As
| Publication number | Publication date |
|---|---|
| JPS53112941A (en) | 1978-10-02 |
| FR2383210B1 (en) | 1985-07-05 |
| FR2383210A1 (en) | 1978-10-06 |
| IT1111612B (en) | 1986-01-13 |
| IT7867509A0 (en) | 1978-03-09 |
| BE864702A (en) | 1978-09-11 |
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