KR20120078625A - Continuous process for preparing rubber-modified styrene polymer from conjugated diene - Google Patents

Abstract

PURPOSE: A continuously manufacturing method of rubber-modified polymer from conjugated diene is provided to reduce energy and CO2 because of not requiring solvent removal process as a stripping function using distillation or water, and not having bale formation through the stripping function by direct distillation of solvent or water. CONSTITUTION: A continuously manufacturing method of rubber-modified polymer comprises a step of manufacturing rubber solution by polymerizing a conjugated diene based-monomer in a first reactor under the presence of solvent; a step of removing solvent by contacting styrene-based monomer to the rubber solution; and a step of conducting polymerization by putting the styrene-based monomer into the rubber solution in a second reactor. The conjugated diene-based monomer is a butadiene, isoprene, or combinations thereof.

Description

Method for continuously preparing rubber-modified styrene polymer from conjugated diene {CONTINUOUS PROCESS FOR PREPARING RUBBER-MODIFIED STYRENE POLYMER FROM CONJUGATED DIENE}

The present invention relates to a method for continuously preparing a rubber-modified styrene polymer from conjugated diene. More specifically, the present invention relates to a method of directly injecting a rubber prepared by solution polymerization into a polymerization process of a rubber-modified styrene-based polymer to reduce energy and CO _{2 and} to improve productivity.

In general, styrene resin is excellent in transparency, thermal stability, processability has been produced a lot of commercially. In particular, high impact polystyrene resins having enhanced impact resistance have been developed by introducing rubber particles into styrene resins. These high impact polystyrene resins disperse rubber, especially polybutadiene particles, having low glass transition temperature (Tg) in monovinylidene aromatic compounds such as styrene, alpha-methyl styrene and ring-substituted styrene in a matrix of styrene polymers. The impact resistance is strengthened.

Rubbers used as impact modifiers for high-impact polystyrene resins, in particular polybutadiene, have a wide variety. There are more than 95% high cis polybutadiene and styrene butadiene copolymer with styrene content of 10-50%, and it is selectively used in the production of high impact polystyrene resin.

1 is a schematic process diagram of a method for continuously preparing a rubber-modified styrene polymer from a conventional conjugated diene. As shown in the related art, a general method for preparing a high impact polystyrene resin is polymerizing butadiene monomer, removing solvent and water through a stripping process, preparing rubber in a bale form, and manufacturing the high impact polystyrene resin. A styrene monomer is dissolved in the ground rubber after a milling step for use in the process. Thereafter, the rubber solution and the styrene monomer dissolved in the styrene monomer were mixed and continuously added to the reactor to polymerize, thereby preparing the final high impact polystyrene. The method includes the step of removing the solvent and water during rubber production and the step of preparing the rubber in the form of a bale, in which case there is a lot of energy consumption due to the use of a large amount of steam and at the same time waste water is generated. In addition, there is a disadvantage in that a lot of energy consumption even when grinding and dissolving the rubber bale.

Several methods have been proposed for separating rubber from rubber solutions.

For example, in US Pat. No. 6,951,901, rubber is polymerized by anionic polymerization using n-hexane as a solvent under n-buthyllithuim catalyst. The remaking process is started.

However, the method also requires a step of polymerizing the butadiene monomer and then removing the solvent using water to separate the rubber and forming a rubber bale, and in order to introduce the rubber bale into the high impact polystyrene resin polymerization process A process of crushing the bale and dissolving it in a styrene monomer is necessary. Therefore, energy is consumed through several steps, and there are disadvantages such as waste water generation and manufacturing cost increase.

Therefore, it is necessary to develop a method capable of directly injecting a rubber solution into a HIPS polymerization process without forming a rubber bale.

An object of the present invention is to continuously prepare a rubber-modified styrene-based polymer from conjugated diene, by preparing a rubber by solution polymerization and then directly supplying the rubber solution to HIPS polymerization, thereby stripping by distillation or water. To provide a method that does not require a solvent removal process.

Another object of the present invention is to provide a method in which energy and CO ₂ can be reduced because there is no bale formation process through direct distillation of solvent or stripping with water.

It is still another object of the present invention to provide a method having excellent productivity since the rubber-modified styrene polymer can be continuously produced from the conjugated diene.

Another object of the present invention is to provide a method for minimizing energy consumption, generating no waste water, and lowering manufacturing costs.

Technical problems to be achieved by the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the following description.

One aspect of the present invention relates to a method of continuously preparing a rubber-modified styrenic polymer from conjugated diene. The method comprises polymerizing a conjugated diene monomer in a first reactor in the presence of a solvent to prepare a rubber solution; Contacting the rubber solution with a styrene monomer to remove the solvent; And it comprises a step of polymerizing in a second reactor by adding a styrene monomer to the rubber solution from which the solvent is removed.

The conjugated diene monomer may be butadiene, isoprene or a combination thereof.

In embodiments, the first reactor may be polymerized using an organometallic catalyst.

In embodiments, the catalyst may be added at 0.04 to 0.5% by weight of the conjugated diene monomer.

After the polymerization in the first reactor, a reaction terminator may be added. In a specific embodiment, the reaction stopper may be added at 0.05 to 0.5 wt% of the conjugated diene monomer.

In one embodiment, the styrene-based monomers may be contacted so that the rubber component may be added in an amount of 8 to 25 wt% when the solvent is removed.

In a specific embodiment, when the styrene-based monomer is added to the rubber solution from which the solvent is removed, the styrene-based monomer and the solvent may be added so that the rubber component becomes 4 to 10% by weight.

In a specific embodiment, the phase change in the second reactor can be reacted to a previous time point to polymerize a solid content of 10-20%.

In addition, after the polymerization in the second reactor, the polymer may be introduced into the third reactor to polymerize a solid content of 30 ~ 50%.

In addition, after the polymerization in the third reactor, the polymer may be introduced into the fourth reactor to polymerize a solid content of 60 ~ 70%. In a specific embodiment, the flow improver may be added to the fourth reactor.

In addition, after the polymerization in the fourth reactor, the polymer may be introduced into the fifth reactor to polymerize a solid content of 72 ~ 85%.

The method does not form a rubber bale.

The present invention is a method of continuously producing a rubber-modified styrene-based polymer from conjugated diene, by preparing a rubber by solution polymerization and then supplying the rubber solution directly to the HIPS polymerization, the solvent by distillation or stripping with water It does not require the removal process, and there is no baling process through direct distillation of solvent or stripping with water, which saves energy and CO ₂ , and it is possible to continuously prepare rubber modified styrene polymer from conjugated diene. It is excellent and has the effect of providing the method of minimizing energy consumption, generating no waste water, and lowering the manufacturing cost.

1 is a schematic process diagram of a method for continuously preparing a rubber-modified styrenic polymer from a conventional conjugated diene.
2 is a schematic process diagram of a method for continuously preparing a rubber-modified styrenic polymer from conjugated diene according to one embodiment of the present invention.
3 schematically shows a continuous polymerization apparatus for continuously preparing a rubber-modified styrenic polymer from conjugated diene according to one embodiment of the present invention.

2 is a schematic process diagram of a method for continuously preparing a rubber-modified styrenic polymer from conjugated diene according to one embodiment of the present invention. The method comprises polymerizing a conjugated diene monomer in a first reactor in the presence of a solvent to prepare a rubber solution; Contacting the rubber solution with a styrene monomer to remove the solvent; And it comprises a step of polymerizing in a second reactor by adding a styrene monomer to the rubber solution from which the solvent is removed.

The conjugated diene monomer may be butadiene, isoprene or a combination thereof.

The conjugated diene monomer may be polymerized to solution polymerization in the presence of a solvent when preparing a rubber solution. The solvent includes n-hexane, cyclo-hexane, toluene, and the like, but is not necessarily limited thereto.

When preparing the rubber solution, the conjugated diene monomer may be added in an amount of 15 to 35 wt% and a solvent of 65 to 85 wt%. The rubber polymerization reaction is stable in the above range.

In embodiments, the first reactor may be polymerized using an organometallic catalyst. The organometallic catalyst includes n-buthyllithuim, ethyllithuim, propyllithuim, isopropyllithuim, tert-buthyllithuim, and the like, but is not limited thereto. In embodiments, the catalyst may be added at 0.04 to 0.5% by weight of the conjugated diene monomer. The rubber polymerization reaction is stable in the above range, and has excellent impact strength and discoloration resistance when producing a rubber-modified styrene polymer. Preferably it can be added at 0.05 to 0.5% by weight of the conjugated diene monomer input amount.

When the conversion rate after polymerization in the first reactor is 98% or more, preferably 100%, additives such as a reaction terminator and an antioxidant may be added.

As the reaction stopping agent Alpha- (nonylphenyl) -omega-hydroxypoly- (oxy-1,2-ethanediyl) and alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol and isopropyl alcohol can be used as the branched phosphate-based reaction terminator. It is not necessarily limited thereto. Of these, alpha- (nonylphenyl) -omega-hydroxypoly- (oxy-1,2-ethanediyl) is preferably a phosphate-based reaction terminator. The reaction stopper may be added at 0.05 to 0.5% by weight of the conjugated diene monomer. In the above range, the rubber component does not discolor and smooth reactivity can be obtained. Preferably it is 0.1-0.3 weight%.

In addition, the antioxidants include Octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, triethylene glycol-bis-3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionate , 4,6-Bis (octylthiomethyl) -o-cresol may be used, but is not necessarily limited thereto. These can be applied individually or in mixture of 2 or more types. Among these, Octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate is preferable. The antioxidant may be added at 0.2 ~ 0.8% by weight of the conjugated diene monomer input amount. There is an advantage of excellent thermal stability in the above range. Preferably it is 0.3-0.6 weight%.

The rubber solution prepared as described above is in a state dissolved in a solvent, and the rubber solution dissolved in the solvent is contacted with a styrene monomer to remove the solvent.

That is, in the present invention, unlike the prior art, the solvent is removed by contacting with a styrene monomer.

The styrene monomers include styrene, α-methylstyrene, α-ethylstyrene, p-methylstyrene, and the like. Among these, preferably styrene.

In the contact method, a rubber solution may be added to a styrene monomer, or a styrene monomer may be added to a rubber solution. At this time, it is preferable to add a styrene monomer so that the rubber component is 8 to 25% by weight. The solvent is removed after the styrene monomer is added, and the solvent may be removed by vacuuming the reactor. The pressure of the reactor is 10 to 755 torr, preferably 50 to 750 torr.

The rubber solution from which the solvent is removed is dissolved in a styrene monomer, and a styrene monomer is added thereto to polymerize the rubber-modified styrene polymer. The styrene monomers include styrene, α-methylstyrene, α-ethylstyrene, p-methylstyrene, and the like. Among these, preferably styrene.

Polymerization for the production of the rubber-modified styrene-based polymer may be applied by block polymerization, solution polymerization and the like. Preferably solution polymerization can be applied.

In an embodiment, the styrene-based monomer and the solvent may be added together to the rubber solution from which the solvent is removed to polymerize. When the styrene monomer and the solvent are added together, the rubber component is added in an amount of 4 to 10% by weight. For example, it is added so that it may become 82 to 94 weight% of a styrene monomer, 4 to 10 weight% of a rubber component, and 2 to 8 weight% of a solvent.

As the solvent, an aromatic solvent such as ethylbenzene, benzene, xylene, toluene, methyl ethyl ketone, or the like may be used.

In the second reactor, the solid phase content may be polymerized to 10-20% by reacting before the phase transition.

Figure 3 schematically shows a continuous polymerization apparatus for continuously producing a rubber-modified styrenic polymer from the conjugated diene according to one embodiment of the present invention. A step is a rubber polymerization process, B is a rubber modified styrene polymerization process.

As shown, the conjugated diene monomer and the solvent are added to the first reactor 10 and polymerized.

The first reactor 10 may be preferably a reactor having a stirrer of a double-helical-ribbon type. The reaction conditions of the first reactor is polymerized for 70 to 150 minutes at 50 ~ 100 ℃.

In the polymerization, when the conversion rate is 98% or more, preferably 100%, a reaction terminator is added, and the styrene monomer is brought into contact with the rubber solution dissolved in the solvent to remove the solvent. Removing the solvent by contacting the styrene-based monomer may be performed in the first reactor 10 or may be performed in a separate reactor. The rubber solution discharged from the first reactor 10 is transferred to the rubber solution reservoir 15 through the line 1. The rubber solution passing through the line 1 is in the state of a rubber solution dissolved in a styrene monomer without a solvent present. The components of the rubber solution are 75 to 92% by weight of the styrene monomer and 8 to 25% by weight of the rubber component. The viscosity of the rubber component (25 ° C) may be in the range of 60 to 200 cps. At this time, the viscosity of the rubber component is prepared by dissolving in styrene monomer 5% by weight and then measured the solution Viscosity of the rubber solution at 25 ℃ using Cannon-Fenske viscosity tube.

The styrene-based monomer and the solvent are again added to the rubber solution reservoir 15 to dissolve the rubber solution. The rubber solution is continuously introduced into the second reactor 20 for polymerizing the rubber-modified styrene polymer through the line (2). The rubber solution passing through the line 2 is in a state in which a rubber solution is dissolved in a styrene monomer and a solvent. The components of the rubber solution are 82 to 94% by weight of the styrene monomer, 4 to 10% by weight of the rubber component and 2 to 8% by weight of the solvent.

The rubber solution is reacted in the second reactor 20 at a temperature of 110 to 135 ° C. for 0.5 to 1.5 hours before the phase transition to produce a first polymer having a solid content of 10 to 20%. The second reactor 20 may be preferably applied to a full charge type in which a polymerization mixture is supplied to the bottom of the reactor in a continuous flow stirred reactor (CSTR), and reactants are directed upward to the reactor.

The first polymer is continuously introduced into the third reactor 30 via the line 3. The third reactor 30 may be polymerized at 125 to 145 ° C. for 1.5 to 3.0 hours to produce a second polymer having a solid content of 30 to 50%. The third reactor 30 may be a continuous flow stirred reactor (CSTR) is applied. In embodiments, a continuous flow stirred reactor (CSTR) with an agitation device in the form of an anchor may be applied.

The second polymer is continuously introduced into the fourth reactor 40 through the line 4 again. The fourth reactor 40 may be reacted at 130 to 150 ° C. for 1.5 to 3.0 hours to generate a third polymer having a solid content of 60 to 70%. The fourth reactor 40 may also be applied to a continuous flow stirred reactor (CSTR). Preferably, the flow improver may be added to the fourth reactor. As the flow improver, mineral oil, silicone oil, or the like may be used. The flow improver It can be used at 1.0 to 5.0% by weight based on the final polymer product after the volatile remover.

The third polymer is continuously introduced into the fifth reactor 50 through the line 5. In the fifth reactor 50, a fourth polymer having a solid content of 72 to 85% may be formed by reacting for 0.5 to 1.0 hour in the range of 140 to 190 ° C. The fifth reactor 50 is divided into four regions from the inlet to the outlet, and a full charge type flow flow reactor capable of temperature control and easy control of reaction heat generated by polymerization may be preferably applied.

The fourth polymer may be added to the volatile remover 60 through the line 6 to remove unreacted monomers and solvents.

As such, the method of the present invention eliminates the need for water removal by introducing a rubber manufacturing process in the first half of the rubber-modified styrene-based polymerization process, and does not require a stripping process for water removal, and does not undergo a rubber bale manufacturing process and a grinding process. It is possible to prepare a high impact polystyrene resin by a conventional manufacturing method.

Hereinafter, the configuration and operation of the present invention through the preferred embodiment of the present invention will be described in more detail. It is to be understood, however, that the same is by way of illustration and example only and is not to be construed in a limiting sense.

Details that are not described herein will be omitted since those skilled in the art can sufficiently infer technically.

Example

Example 1

25 wt% butadiene monomer and 75 wt% normal hexane were added to the first reactor, and then 0.04 wt% of the butadiene monomer was added to the catalyst n-buthyllithuim (Aldrich's 15 wt% diluent). Polymerization at 2.0 hours. When the conversion ratio of butadiene monomer is 100%, 0.2 wt% of the butadiene monomer is added to the reaction terminator (HPSS-81, manufactured by IC Chemical Co., Ltd.), and 0.4 wt% of the butadiene monomer is added to the antioxidant (SONGNOX 1076). It was. The styrene monomer was added to the rubber solution dissolved in the prepared normal hexane, the styrene monomer was added so that the rubber component was 12% by weight, and the normal hexane was removed under a vacuum condition of 200 torr. After the rubber solution dissolved in the styrene monomer prepared above was transferred to a rubber solution reservoir, the styrene monomer, rubber component, and ethylbenzene in the rubber solution reservoir each contained 89% by weight of styrene monomer, 6% by weight of rubber component, and 5% of ethylbenzene. Styrene monomer and ethyl benzene were added to the rubber solution reservoir so as to be the weight%. The rubber solution dissolved in the styrene monomer and ethylbenzene was continuously added to the second reactor of the high-impact polystyrene polymerization process and reacted at 125 ° C. for 1.0 hour in the second reactor until the phase transition point before the first phase having a solid content of 13%. A polymer was produced and the first polymer was continuously introduced into a third reactor to polymerize at 135 ° C. for 2.0 hours to produce a second polymer having a solid content of 40%. While continuously adding the second polymer to the fourth reactor and adding 2.0% by weight of mineral oil, which is a flow improver, was reacted at 140 ° C. for 2.0 hours to produce a third polymer having a solid content of 65% and adding the third polymer. Continuously added to the fifth reactor was reacted for 0.8 hours in the range of 150 ~ 170 ℃ to prepare a fourth polymer having a solid content of 75%. The fourth polymer was added to a volatile remover to remove unreacted monomer and solvent, and then pelletized to prepare a final polymerized product.

Example 2

The same process as in Example 1 was carried out except that the amount of n-buthyllithuim catalyst in the first reactor was changed to 0.2% by weight and the residence time was changed to 1.5 hours.

Example 3

The same process as in Example 1 was carried out except that the amount of n-buthyllithuim catalyst in the first reactor was changed to 0.5 wt% and the residence time was changed to 1.1 hours.

Comparative Example 1

The same process as in Example 1 was carried out except that the amount of n-buthyllithuim catalyst in the first reactor was changed to 0.03 wt% and the residence time was changed to 3.0 hours.

Comparative Example 2

The same process as in Example 1 was carried out except that the amount of n-buthyllithuim catalyst in the first reactor was changed to 0.6 wt% and the residence time was changed to 1.1 hours.

Comparative Example 3

In the same manner as in Example 1, except that the amount of n-buthyllithuim catalyst in the first reactor was changed to 0.2% by weight, the amount of reaction stopper was changed to 0.04% by weight, and the residence time was changed to 1.5 hours.

Comparative Example 4

In the same manner as in Example 1, except that the amount of n-buthyllithuim catalyst in the first reactor was changed to 0.2% by weight, the amount of reaction stopper was changed to 0.6% by weight, and the residence time was changed to 1.5 hours. Normal polymerization was not possible due to the residual polymerization terminator.

Resin characterization and physical property analysis of the injection molded product were performed on the prepared final polymer.

(1) Izod impact strength was measured by ASTM D256 (unit: kgfcm / cm).

(2) Flowability: measured by ASTM D1238 (g / 10min, 5kg, 200 ° C).

(3) Heat resistance property: It measured by ISO R306B (5 kg, 50 degreeC / hr, degreeC).

(4) Rubber particle size: measured by Malvern's Mastersizer S Ver 2.14 (㎛).

(5) Yellowness Index (Yellow Index): It was measured by SUGA Test Instrument Co., Ltd. SM-T45-H1 model.

(6) Solution Viscosity: A rubber solution sample dissolved in normal hexane polymerized in the first reactor was taken to remove normal hexane, and only rubber components were taken. The rubber thus prepared was dissolved in styrene monomer to prepare 5 wt%, and the solution Viscosity of the rubber solution was measured at 25 ° C. using a Cannon-Fenske viscosity tube.

division Example Comparative example One 2 3 One 2 3 4 First reactor
n-buthyllithuim 0.04
weight% 0.2 wt% 0.5
weight% 0.03
weight% 0.6
weight% 0.2
weight% 0.2
weight% Reaction stopper 0.2 wt% 0.2 wt% 0.04% by weight 0.6
weight% Residence time 2.0 1.5 1.1 3.0 1.1 1.5 1.5 Solution Viscosity 200
cps 170
cps 100
cps reaction
Impossible 60
cps 170
cps
color
Bad 170
cps Second reactor Solid content 13% Reaction temperature 125 ℃ Stirring speed 145 rpm Residence time 1.0 hours
Third reactor Solid content 40% Reaction temperature 135 ℃ Stirring speed 100 rpm Residence time 2.0 hours Fourth reactor Solid content 65% Reaction temperature 140 ° C Stirring speed 20 rpm Residence time 2.0 hours 5th reactor Solid content 75.0% Reaction temperature 1 zone / 2 zone / 3 zone / 4 zone = 150 ° C / 155 ° C / 160 ° C / 170 ° C Residence time 0.8 hours Properties
result Impact strength 12.3 12.2 12.5 Rubber
polymerization
Reactor
reaction
Impossible 4.5 12.1 polymerization
Impossible liquidity 3.5 3.4 3.6 3.9 3.5 Heat resistance characteristic (VST) 90 89 91 90 88 Rubber Particle Size 2.7 2.8 2.6 0.6 2.7 Yellow road 7.5 8.0 -7.0 7.3 20.0

As shown in Table 2, when the amount of catalyst input as shown in Comparative Example 2, the rubber polymerization reaction did not proceed, when the catalyst is added in excess as shown in Comparative Example 3, the molecular weight of the polymerized rubber is lowered and polymerized rubber The solution viscosity of was lowered to 60cps, and the impact strength was sharply lowered due to the smaller rubber particle size of the final product when manufacturing high impact polystyrene resin. When the amount of the reaction terminator was small as in Comparative Example 4, the polymerized rubber component became colored, and the yellowness of the final product increased sharply when the high impact polystyrene resin was prepared. When the reaction stopper was added in an excessive amount as in Comparative Example 5, a high reactivity polystyrene resin produced caused a sharp decrease in reactivity, and thus, normal operation was not possible.

Although the embodiments of the present invention have been described above with reference to the accompanying drawings and tables, the present invention is not limited to the above embodiments, but may be manufactured in various forms, and common knowledge in the art to which the present invention pertains. Those skilled in the art can understand that the present invention can be implemented in other specific forms without changing the technical spirit or essential features of the present invention. It is therefore to be understood that the embodiments described above are in all respects illustrative and not restrictive.

10: first reactor 20: second reactor
30: third reactor 40: fourth reactor
50: fifth reactor 60: volatile remover

Claims (14)

Preparing a rubber solution by polymerizing the conjugated diene monomer in a first reactor in the presence of a solvent;
Contacting the rubber solution with a styrene monomer to remove the solvent; And
Adding a styrene monomer to the rubber solution from which the solvent was removed to polymerize in the second reactor;
A method for continuously producing a rubber-modified styrene polymer from the conjugated diene, characterized in that it comprises a step.
The method of claim 1, wherein the conjugated diene monomer is butadiene, isoprene or a combination thereof.
The method of claim 1, wherein the polymerization is carried out using an organometallic catalyst in the first reactor.
The method of claim 3, wherein the catalyst is characterized in that the addition of 0.04 to 0.5% by weight of the amount of conjugated diene monomer.
The method of claim 1, wherein the reaction terminator is added after the polymerization in the first reactor.
The method of claim 5, wherein the reaction stopping agent is characterized in that the addition of 0.05 to 0.5% by weight of the amount of conjugated diene monomer.
The method of claim 1, wherein the styrene-based monomer is brought into contact with the rubber component so as to be added in an amount of 8 to 25% by weight when the solvent is removed.
The method of claim 1, wherein a styrene monomer and a solvent are added to the rubber solution from which the solvent is removed so that the rubber component is 4 to 10% by weight during polymerization.
The method according to claim 1, wherein the second reactor reacts to a previous point of phase transition to polymerize a solid content of 10-20%.
The method according to claim 1, wherein after the polymerization in the second reactor, the polymer is introduced into a third reactor to polymerize a solid content of 30 to 50%.
The method according to claim 10, wherein after the polymerization in the third reactor, the polymer is introduced into a fourth reactor to polymerize a solid content of 60 to 70%.
12. The method of claim 11, wherein a flow enhancer is added to the fourth reactor.
12. The method of claim 11, wherein after the polymerization in the fourth reactor, the polymer is introduced into a fifth reactor to polymerize a solid content of 72 to 85%.
12. The method of claim 11, wherein the method does not form a rubber bale.

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