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EP0980394A1 - Procede de bromation des resines de polystyrene - Google Patents

Procede de bromation des resines de polystyrene

Info

Publication number
EP0980394A1
EP0980394A1 EP98914612A EP98914612A EP0980394A1 EP 0980394 A1 EP0980394 A1 EP 0980394A1 EP 98914612 A EP98914612 A EP 98914612A EP 98914612 A EP98914612 A EP 98914612A EP 0980394 A1 EP0980394 A1 EP 0980394A1
Authority
EP
European Patent Office
Prior art keywords
brominated polystyrene
polystyrene
bromine
brominated
polymer
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP98914612A
Other languages
German (de)
English (en)
Inventor
Billie B. Dadgar
Donald E. Balhoff
Charles H. Kolich
Meng-Sheng Ao
Homer C. Lin
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Albemarle Corp
Original Assignee
Albemarle Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
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First worldwide family litigation filed litigation Critical https://patents.darts-ip.com/?family=25313400&utm_source=google_patent&utm_medium=platform_link&utm_campaign=public_patent_search&patent=EP0980394(A1) "Global patent litigation dataset” by Darts-ip is licensed under a Creative Commons Attribution 4.0 International License.
Application filed by Albemarle Corp filed Critical Albemarle Corp
Priority to EP02028733A priority Critical patent/EP1293519B1/fr
Priority to EP02028731A priority patent/EP1293517B1/fr
Priority to EP10001769.8A priority patent/EP2189480B1/fr
Priority to EP10001768.0A priority patent/EP2189479B1/fr
Priority to EP02028732.2A priority patent/EP1293518B1/fr
Publication of EP0980394A1 publication Critical patent/EP0980394A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F8/00—Chemical modification by after-treatment
    • C08F8/18—Introducing halogen atoms or halogen-containing groups
    • C08F8/20—Halogenation

Definitions

  • This invention relates to novel, high quality brominated polystyrenes which are especially suitable for use as flame retardants in thermoplastic formulations.
  • Brominated polystyrenes are well established as flame retardants for use in thermoplastics, e.g., polybutylene terephthalate, polyethylene terephthalate and nylon. Recently, interest has been shown for expanding their use to syndiotactic polystyrene and polycyclohexylene dimethylene terephthalate.
  • brominated polystyrenes are produced by a reaction between polystyrene and a brominating agent (e.g., bromine or bromine chloride) in the presence of a solvent (e.g., dichloroethane) and a Lewis acid catalyst.
  • a brominating agent e.g., bromine or bromine chloride
  • the bromine and chlorine content, and the color (it is believed) are properties of the structure of the particular brominated polystyrene being considered.
  • the bromine content applies to the sum of (1) the bromine which is substituted onto the aromatic portions of the polymer, (2) the bromine which is substituted onto the alkyl portion of the polymer, e.g., the polymer backbone or which is present due to alkylation of the aromatic portion of the polymer, and (3) any ionic bromine present, e.g., sodium bromide.
  • the alkylation reaction is catalyzed by the Lewis acid catalyst and uses the reaction solvent (usually a 1 - 3 carbon atom dihaloalkane) as the alkylating agent.
  • the bromine for (1) is referred to herein as aromatic bromide, while the bromine for (2) is referred to as alkyl bromide.
  • ionic bromine hereinafter ionic bromide
  • Ionic bromide is not part of the polymer structure and is usually washed almost entirely from the brominated polymer product before the bromine content is measured.
  • the color of the brominated polystyrene is also believed to be due to polymer structure and not the result of some discreet impurity. Color may be caused by the above-mentioned alkyl bromide and/or the below-mentioned alkyl chloride substituents on the aromatic moieties.
  • the chlorine content is credited to chlorine which, like the bromine, is part of the polymer structure as an aromatic and/or an alkyl chloride.
  • the use of bromine chloride as the brominating agent is the largest contributor to the chlorine content.
  • the brominated polystyrene have a minimized alkyl bromide and/or alkyl chloride, i.e., alkyl halide, content.
  • Alkyl halides are not desirable as they are not as thermally stable as are aromatic halides and, thus, they can be easily converted to hydrogen halide, e.g., HBr or HC1, under normal end-use processing conditions. Hydrogen halide, in the presence of moisture, can cause severe corroding of metal process equipment. Also, there is the matter of color, which is also believed to be impacted by some alkyl halides.
  • a brominated polystyrene having almost all aromatic bromide will have desirable flame retarding characteristics as the bromine will not leave the aromatic moiety at processing temperatures, but rather, will leave at the very high temperatures which are encountered in the vicinity of an approaching flame front.
  • the halide is present as an aromatic or an alkyl halide, it is also desirable to minimize the total chlorine content of the brominated polystyrene as chlorine is not as efficacious or as stable a flame retardant constituent as is bromine.
  • prior art brominated polystyrenes do not exhibit high thermal stability.
  • Prior art polymers exhibit a 1% weight loss at temperatures less than 336° C when submitted to Thermo- gravimetric Analysis (TGA) and, indeed, most exhibit a 1% weight loss at temperatures around 300°
  • This invention provides for a novel brominated polystyrene which is very thermally stable as is evidenced by the polymer having a TGA 1 % weight loss at a temperature in excess of 340° C and, preferably, within the range of from 340° C to 380° C and, most preferably, within the range of from 345° C to 380° C. Most highly preferred is a TGA value at 1% weight loss which is within the range of from 345° C to 375° C. Comparisons between the low TGA values for prior art products and the TGA values for polymers of this invention are reported in the Examples and Tables infra. The high TGA temperatures which are characteristic of the polymers of this invention are not believed to be due to post reaction purification techniques. Rather, it is speculated that the enhanced thermal stability is due to the chemical makeup of the brominated polystyrene.
  • This invention also provides for a novel thermally stable brominated polystyrene which is comprised of polymer units having the formula:
  • each X is independently -H or a hydrolyzable halide, the identity of each X for each polymer unit being such that the brominated polystyrene contains less than 6,000 ppm hydrolyzable halides, and wherein the value of n for each polymer unit is such that the brominated polystyrene contains at least 68 wt% bromine.
  • preferred brominated polystyrenes will be those in which the hydrolyzable halide is bromide.
  • Such polymers may contain some hydrolyzable chloride, but the amount will be insignificant, say less than 100 ppm. If chlorine is present, its source would probably be the Lewis acid catalyst or the solvent used in the preparation of the brominated polystyrene.
  • Preferred brominated polystyrene polymers are those in which the chlorine content is not detectable in accordance with X-Ray Fluorescense analysis. It is beneficial, from the viewpoint of economy and performance, that the hydrolyzable bromide content be less than 4,000 ppm, say within the range of from 1,000 ppm to 3,000 ppm.
  • the brominated polystyrene of this invention are unique in that, from their very inception, the polymer has the very low hydrolyzable halide content discussed above. This is an important aspect as the polymers do not need further treatment to reduce the hydrolyzable halide content. Reduction of the hydrolyzable halide content, say by hydrolysis, is not desirable as it yields a polymer having hydrolysis residues, e.g., OH, in its structure which can alter the polymer's properties. It is preferred that the brominated polystyrenes of this invention contain little or no hydrolysis residues, say less than 500 ppm and preferably less than 100 ppm. The most preferred brominated polystyrenes of this invention will be those which provide, at the lowest cost, the highest bromine content and the lowest hydrolyzable halide content which obtain the desired performance.
  • This invention also provides for a brominated polystyrene having an actual M w which is within 20% of its calculated theoretical M w , the theoretical M w being based upon the actual bromine content of the brominated polystyrene and the M w of the polystyrene reactant used to produce the brominated polystyrene.
  • a difference between the actual M w and the theoretical M w , outside of the normal ⁇ margin of error for GPC analysis, is evidence of either cross-linking (increases the M w ) or polymer chain cleavage (decreases the M w ).
  • the 20% difference mentioned above for the brominated polystyrenes of this invention includes the ⁇ margin of error.
  • Preferred differences are those less than 20%, with differences of less than 10% being most preferred. Since GPC techniques can give different but similar values for the same polymer tested, defining a brominated polystyrene as being of this invention is best performed by taking the arithmetic average of five consecutive GPC determinations of the polymer to be tested. Other data averaging techniques are suitable, such as using the average of 10 consecutive GPC determinations with discard of the high and low values, the only requirement being that accurate and reproducible results are obtained.
  • the polystyrene reactant used in the production of the brominated polymers of this invention can be any of those which are commercially available. Generally, the polystyrene backbone will not have been hydrogenated and, thus, will have unsaturation. There is no need for the brominated polymers of this invention to be produced from anionically produced polystyrene as is taught in EPO 0 201 411; in fact, it is preferred that the polystyrene reactant not be an anionically produced polystyrene as such polymers are expensive and not readily available.
  • the aromatic pendant constituents of the polymer can be alkyl substituted, but in most cases, will not be so substituted.
  • the polystyrene used to produce the brominated polystyrenes of this invention will have a M w within the range of from 500 to 500,000 and a polydispersity within the range of from above 1 to 4.
  • the polystyrene reactant will have a M w within the range of from 100,000 to 300,000 and will have a polydispersity within the range of from 1.25 to 2.5.
  • the lower molecular weight polystyrene reactants will have a M w within the range of from 500 to 100,000 and a polydispersity less than 10 and preferably within the range of from above 1 to 4.
  • Higher molecular weight polymer reactants of this invention have a M w within the range of from 300,000 to 500,000 and a polydispersity within the range of from above 1 to 4.
  • the M w and polydispersity values are both based on gel permeation chromatography (GPC) techniques which are hereinafter described.
  • GPC gel permeation chromatography
  • the polystyrene used in the formation of the brominated polystyrenes of this invention not contain any additives, such as zinc stearate, paraffins, and mineral oils.
  • a highly preferred polystyrene is Styron ® 612 which is marketed by The Dow Chemical Company of Midland, Michigan.
  • the brominated polystyrenes of this invention exhibit additional superior physical properties, e.g., color. For flame retardants, color is an important property, with pure white being the ultimate goal. Due to the formation of various color bodies by all bromination processes, the industry has accepted near-white products as being acceptable.
  • the color of prior art brominated polystyrene expressed as a solution ⁇ E value, generally will fall within the range of 20 to 35.
  • the brominated polystyrenes of this invention feature ⁇ E values of less than 20 and preferably within the range of from 5 to 18. Most preferably, the ⁇ E value will be within the range of from 5 to 15.
  • brominated polystyrenes of this invention Another physical property of the brominated polystyrenes of this invention is that they have essentially no or very little odor when heated to a temperature above 150° C.
  • Ferro Corporation's Pyro-Chek ® brominated polystyrene flame retardant has a noticeable and strong odor at 150° C.
  • the strong odor is believed to be attributable to the presence of bromochloroethanes, e.g., bromodichloroethane, dibromochloroethane, dibromodichloroethane and tribromochloroethane, which are in the Pyro-Chek ® 68PB product.
  • bromochloroethanes are not seen in detectable quantities in the brominated polystyrenes of this invention.
  • the brominated polystyrenes of this invention are used in amounts which are within the range of from 5 to 20 wt%, the wt% being based on the total weight of the formulation.
  • the thermoplastics which may be most benefited by the subject brominated polystyrenes are polyethylene terephthalate, polybutylene terephthalate, polycyclohexylene dimethylene terephthalate, and nylon.
  • Conventional additives, such as antimony flame retardant synergist, antioxidants, UV stabilizers, pigments, impact modifiers, fillers, acid scavengers, and blowing agents, can be included with the formulations or foams as is appropriate. Analytical Methods
  • brominated polystyrene Since brominated polystyrene has good solubility in solvents such as tetrahydrofuran (THF), the determination of the total bromine content for the brominated polystyrene is easily accomplished by using conventional X-Ray Fluorescence techniques.
  • the sample analyzed is a dilute sample, say O.l ⁇ 0.05 g brominated polystyrene in 60 mL THF.
  • the XRF spectrometer can be a Phillips PW1480 Spectrometer. A standardized solution of bromobenzene in THF is used as the calibration standard.
  • the bromine values described herein and reported in the Examples are all based on the XRF analytical method.
  • the alkyl halide constituents of the brominated polystyrene are hydrolyzed with ethanolamine to yield amine hydrogen halide by-product which remains in the reaction mix.
  • the reaction mix is then titrated with AgNO 3 which will measure the amount of amine hydrogen bromide, amine hydrogen chloride and any ionic bromide and ionic chloride present in the starting material.
  • the amount of hydrolyzable bromide is determined by subtracting the ionic bromide content from the total bromide value just obtained.
  • the ionic bromide content is obtained by washing a separate sample of the brominated polystyrene being tested with water and measuring by AgN0 3 titration of the ionic bromide content in the wash water. Generally, the ionic bromide content will be low.
  • the flask contents are swirled to homogenize the solution (liquid portion), then the solution is carefully drained into a 400 mL tall form beaker containing a magnetic stirrer bar. Care is taken to keep any solution from running back along the flask neck.
  • the neck is washed inside and out with methanol to avoid loss of halogen.
  • the interior of the flask and the polymer cake are both rinsed several times with methanol in the same manner to remove surface solution, the washings all being collected in the beaker.
  • the beaker should now contain no more than 100 mL.
  • To the washed polymer cake in the Iodine flask is added 20 mL of reagent-grade dioxane.
  • the flask is stoppered and gently warmed with periodic swirling until the polymer dissolves.
  • the beaker is placed on a magnetic stirrer and the contents stirred rapidly. Then the dioxane and cake solution is slowly poured into the beaker.
  • the polymer precipitates in a very finely-divided form.
  • the outside of the neck and the interior of the Iodine flask is rinsed with methanol.
  • the residual polymer coagulates and the contents of the Iodine flask are washed into the beaker.
  • the flask is washed several more times to insure complete removal of halogen. At this point, the beaker should contain no more than 0150 mL.
  • ppm Br CmL AgNO : )x (normality AgNO- x T7.99 x 10") sample weight in grams
  • ppm Cl " (mL AgNO 3 Yx (normality AgNQ 3 ) x (3.545 x 10 4 sample weight in grams
  • the stirred bottle contents are acidified with 1 : 1 H 2 SO 4 to obtain a pink color.
  • the resultant solution is titrated with 0.01 N AgNO 3 using an automatic potentiometric titrator, such as a Methrom 716.
  • the ionic bromide content is calculated as follows:
  • ppm ionic bromide (mL AgNO 3 x (normality AgNO 3 ) x (7.99 x 10 4 ) sample weight in grams
  • brominated polystyrenes of this invention use is again made of the ready solubility of brominated polystyrene in easy-to-obtain solvents, such as chlorobenzene.
  • the analytical method used is quite straight-forward. Weigh 5 g ⁇ 0.1 g of the brominated polystyrene into a 50 mL centrifuge tube. To the tube also add 45 g ⁇ 0.1 g chloroben- zene. Close the tube and shake for 1 hour on a wrist action shaker. After the 1 hour shaking period, examine the solution for undissolved solids. If a haze is present, centrifuge the solution for 10 minutes at 4,000 rpm.
  • Thermogravimetric analysis is used to test the thermal behavior of both prior art brominated polystyrene and the brominated polystyrenes of this invention.
  • the TGA values are obtained by use of a TA Instruments Thermogravimetric Analyzer. Each sample is heated on a Pt pan from 25° C to 600° C at 10° C/min with a nitrogen flow of 50 - 60 ml/min.
  • the M w values were obtained by GPC using a Waters model 510 HPLC pump and, as detectors, a Waters Refractive Index Detector, Model 410 and a Precision Detector Light Scattering Detector, Model PD2000.
  • the columns were Waters, Styragel, 500A, 10,OO ⁇ and 100,000 A.
  • the autosampler was a Shimadzu, Model Sil 9A.
  • a polystyrene standard (M w 185,000) was routinely used to verify the accuracy of the light scattering data.
  • the solvent used was tetrahydro- furan, HPLC grade.
  • the test procedure used entailed dissolving 0.015 - 0.020 g of sample in 10 mL of THF.
  • M w BrPS M W PS + (M... PS ⁇ Atom. wt. Br - Atom, wt. H ⁇ Mol. wt. Stv. 0.0nCwt% Br)
  • PS is used interchangeably with and meant to designate polystyrene, while Sty. means styrene.
  • M w means weight average molecular weight as determined by GPC (light scattering detector) described infra.
  • a mixture of 770.0 g bromochloromethane (BCM, 9 ppm water) and 2.775 g A1C1 3 was prepared in a 5-L jacketed glass reactor equipped with a mechanical paddle stirrer, condenser, and thermowell.
  • the reactor and mixing tee were cooled with a circulating glycol bath to maintain a temperature of 0° C to 2° C throughout the 1 hour feed time and subsequent 1 hour cook.
  • the reaction mixture was then washed with water and neutralized with a mixture of aqueous sodium gluconate, sodium sulfite, and sodium hydroxide.
  • the solution was added dropwise to 1.8 L hot (90° C - 94° C) water containing 0.25 g dioctyl sulfosuccinate sodium salt (surfactant) to precipitate the product and distill the solvent.
  • the slurry was filtered and the off-white solid was washed with water. Drying to constant weight at 150° C gave 389.8 g.
  • EDC 1 ,2-dichloroethane
  • Example II was repeated using 230.8 g (2.00 mole) commercial bromine chloride with 80.20 g (0.770/n mole) polystyrene and 11.77 g Sb 2 0 3 .
  • the water washed and neutralized organic phase was divided into two equal portions. One portion was added to 1.5 L of methanol as in Example I to obtain 101.6 g of light yellow solid (product A) after drying to constant weight at 150° C. The other portion was added dropwise to 1.9 L of hot (89° C - 94° C) water to precipitate the product and distill the solvent.
  • the dry light yellow solid (product B) weighed 100.3 g.
  • the PS solution was pumped from the bottom valve of this feed reservoir to a jacketed, glycol-cooled mixing tee mounted on the reaction flask.
  • bromine was pumped from a tared feed reservoir to the same mixing tee where it combined with the polystyrene solution before dropping into the stirred catalyst suspension in the reaction flask.
  • Two Masterflex ® 7550-90 pumps were used.
  • the PS feed system used an all-Teflon feed line with pump head 77390 operating at a constant speed of 60 rpm. This provided a constant feed rate of 21.02/n mmol PS/min (21.89 g/min).
  • the bromine feed system used a combination of Teflon and Viton tubing with pump head 7518-10 operating at a rate of 70.05 mmol/min for the first 18 min, 38.80 mmol/min for 18 - 23 min, and 56.75 mmol/min for 23 - 165 min. Both feeds ended at 165 min.
  • the overall mol ratio of Br 2 /PS was 2.70.
  • a rinse of 260.95 g of dry BCM was used for the PS solution feed system to assure complete transfer of the polymer to the reaction flask.
  • the reaction temperature was maintained at 0° C to 4° C throughout the addition and subsequent 2.3 hour cook period (with nitrogen purge of the reactor overhead).
  • the weight increase for the caustic exit gas scrubber was 665.4 g (87.8% of theory for HBr).
  • the catalyst was deactivated by addition of 125.0 g of a 10 wt% aqueous solution of sodium gluconate. A 63.41 g portion of 10 wt% aqueous sodium sulfite was added, and the pH was adjusted to 14 by addition of 423.0 g of 10 wt% aqueous NaOH. After dilution with BCM (1334.6 g), the organic phase was separated and then washed with water (1011.8 g).
  • Example IV (Of the Invention) The procedure of Example IV was followed except that: a 2-L flask and 40 g of polystyrene were used; the A1C1 3 wt% (based on polystyrene) was 2.0 wt%; the feed mole ratio of bromine to polystyrene was 3.33; the total equivalents of bromine was 2.78; the temperature range was 0° C to 5° C; the feed times for the bromine/polystyrene was 32 min 38 min; and the cook time was 150 minutes.
  • Table 2 gives some of the properties of the brominated polystyrenes produced in Examples IV and V.
  • the brominated polystyrenes of this invention are not conventionally produced.
  • a suitable process comprises feeding a mixture of bromine and a solution of bromochloromethane and polystyrene (2.5 to 5 moles of bromine per mole of styrene in the polystyrene) to a reactor containing a further amount of bromochloromethane and a catalytic amount of A1C1 3 .
  • the mixture of polystyrene, bromochloromethane and bromine is substantially free of a bromination catalyst.
  • the phrase, "substantially free of a bromination catalyst”, is to be taken to mean less than a catalytically effective amount of catalyst. With such low amounts of catalyst, little or no catalyzed bromination or cross-linking should occur. Generally, such amounts will be less than 500 ppm based on the weight of polystyrene reactant present.]
  • the reaction temperature will be within the range of from 0° C to 10° C. After the reaction mass is formed, it is cooked 0.5 to 3 hours. After the cook period, the reaction product is worked up by adding sodium sulfite, sodium gluconate and sodium hydroxide to deactivated the catalyst, kill any remaining brominating agent and to adjust the reaction mass pH.
  • reaction mass is settled to obtain a two-phase reaction mass containing an organic phase, which contains, as a solute, the brominated styrenic polymer product and an aqueous phase.
  • the aqueous phase is decanted and the remaining organic phase is stripped of its solvent component. It is most convenient to accomplish this strip by pouring the organic phase into boiling water.
  • the brominated styrenic polymer product forms a precipitate.
  • the precipitate can be recovered by any liquid-solid separation technique, e.g., filtration and centrifugation. The recovered precipitate is then dried.
  • the iron content be kept to a minimum, say less than 10 ppm iron.
  • the introduction of iron into the product usually occurs due to iron equipment which is in contact with the reaction and product streams.
  • process equipment which does not act as a source of iron contamination.
  • the equipment can be glass-lined or corrosion resistant alloy.
  • Figure 1 is a schematic diagram depicting a process suitable for producing brominated polystyrenes of this invention.
  • polystyrenes that are useful to produce the brominated polystyrenes of this invention via the instant process are any of those which have been described supra. Also, as mentioned previously, it is preferred that the polystyrene be additive-free. Again, a most preferred polystyrene reactant is Styron ® 612 which is marketed by The Dow Chemical Company.
  • the catalyst used in the processes of this invention can be any of the aluminum based catalysts, e.g., A1C1 3 , AlBr 3 and Al. Mixtures of aluminum catalysts can also be used. Once the catalyst has been added to the reaction system, it may undergo some reaction without significant loss of catalytic activity, e.g., A1C1 3 may convert to some extent to AlBr 3 . A1C1 3 , because of its availability and price, is the catalyst of choice. The catalyst is used in an amount which is sufficient to obtain the catalytic effect sought.
  • catalytic amounts will depend on the activity of the catalyst, but will generally fall within the range of from 0.2 to 5 weight percent and preferably within the range of from 0.5 to 5 weight percent, based on the weight of the styrenic polymer being brominated. The most active catalysts will be used in the lower amounts, while the less active catalysts will be used in the higher amounts. When A1C1 3 is the catalyst, amounts within the range of from 0.5 to 3 weight percent are preferred.
  • the brominating agent is preferably bromine.
  • Bromine can be obtained commercially in the diatomic form or can be generated by the oxidation of HBr.
  • Br 2 can be supplied either as a liquid or a gas.
  • the amount of brominating agent used in the process should provide an overall mole ratio of total brominating agent to total styrenic polymer fed which will provide from 1 to 3 bromine substitutions per styrenic monomer unit in the polymer. It is preferred that the brominated polymer of this invention contain above 68 w ⁇ % bromine and most preferably within the range of from 69 to 71 wt% bromine.
  • the amount of brominating agent used in the process will be determined by the bromine content desired considering the highest bromine content which is obtainable with the process parameters chosen. The higher bromine contents will require the most brominating agent. It is pointed out that as perbromination is approached, it becomes more difficult to substitute the last bromines. Adding ever larger amounts of a brominating agent does not always attenuate this difficulty. However, it is helpful, in attempting to maximize the bromine content, to provide a small stoichiometric excess of brominating agent. Stoichiometric excesses up to 10% are preferred. The stoichiometry is easily determined as it requires one mole of Br 2 per substitution sought.
  • the practitioner will determine the bromine content sought on a weight basis and then will calculate, on an idealized basis, the number of moles of brominating agent needed to obtain the same. For example, if the styrenic polymer is polystyrene and the bromine content sought is 68 wt%, at least 2.7 moles of bromine per styrenic monomer unit will be required, not including any desired stoichiometric excess.
  • All of the bromine can be added with the polystyrene-bromochloromethane solution or a portion of the bromine can be pre-added to the reactor with the remainder being added with the solution. If pre-addition is to be used then the pre-added portion will amount to 0.5 to 5% of the total bromine used in the process. While the foregoing describes the overall quantitative relationship between the brominating agent and styrenic polymer, the quantitative relationship between these two reactants in the feed mixture has not been fully discussed. Generally, the mixture which is to be fed is formed from 1 to 8 moles of brominating agent per mole of styrenic monomer units at any time during the feed period.
  • the quantitative relationship can be constant or can vary within the above-mentioned range. (It is within the scope of this invention to allow for some excursions outside of the range so long as such does not do significant harm to the process efficiency or to product quality.)
  • a preferred range is from 2.5 to 5 moles of brominating agent per mole of styrenic monomer units to form the feed mixture.
  • the use of an amount of brominating agent in the feed mixture which gives a mole ratio of brominating agent to styrenic monomer units which is less than or greater than the selected overall mole ratio of brominating agent to styrenic monomer units will result in exhaustion of either the brominating agent or the styrenic polymer as a mixture constituent before exhaustion of the other constituent.
  • an overall molar ratio of bromine to styrenic monomer units of 3.0:1, and any excess if desired would be suitable.
  • the practitioner chooses to form a feed mixture in which the molar ratio of bromine to styrenic monomer units is 1 :1. It can be seen that the amount of polystyrene to be fed will be completed before obtaining the needed overall amount of bromine. In this case, the practitioner first uses the 1 : 1 mixture and then continues on with just a bromine feed after the polystyrene feed has been exhausted. If, on the other hand, the molar ratio in the feed mixture is chosen to be 5: 1 , then the bromine will first become exhausted and the feed will have to be finished with the polystyrene alone. Generally, it is preferred to have the overall molar ratio and the feed mixture ratio at least somewhat similar. In all cases though, the initial feed should preferably contain at least a molar ratio of bromine to styrenic monomer units of 1 : 1.
  • the bromine used in the process of this invention be essentially anhydrous, i.e., contain less than 100 ppm (weight basis) water and contain no more than 10 ppm organic impurities, e.g., oil, grease, carbonyl containing hydrocarbons, and iron. Available, commercial grade bromine may have such purity. If, however, such is not available, the organic impurities and water content of the bromine can be conveniently reduced by mixing together a 3 to 1 volume ratio of bromine and concentrated (94 - 98 percent) sulfuric acid. A two-phase mix is formed which is stirred for 10 - 16 hours. After stirring and settling, the sulfuric acid phase, along with the impurities and water, is separated from the bromine phase. To further enhance the purity of the bromine, the recovered bromine phase can be subjected to distillation.
  • the bromochloromethane solvent is preferably essentially anhydrous, containing less than
  • the instant process benefits from the reaction mass being in an anhydrous condition. Water tends to affect the catalytic activity of the aluminum catalyst, which effect may hinder the quick aromatic bromination of the styrene rings. If, for some reason, the practitioner has large amounts of water in the process and dewatering is not practical, then it may be possible to overcome the situation by simply increasing the amount of catalyst used. For the instant process, it is not a feature to use water to avoid cross-linking as is taught in U.S. 4,200,703, but rather, the subject process attenuates cross-linking by means which include the novel feeding of a non-catalyzed mixture of polystyrene and bromine to a reactor containing a catalyst.
  • the solutions of this invention preferably contain from 5 to 50 wt% polymer. More highly preferred are those which contain from 5 to 30 wt% polymer.
  • the bromination catalyst to which the bromine/styrenic polymer mixture is fed, to be in association with bromochloromethane so that the catalyst can be in a solution, slurry, dispersion or suspension. Such will enhance reaction mass mixing and mass transfer qualities.
  • the mixture of bromochloromethane and catalyst is best described as a suspension. Generally, it is suitable to use from 95 to 99.9 wt%, preferably from 99 to 99.8 wt%, bromochloromethane, based on the total weight of bromochloromethane and catalyst.
  • the styrenic polymer/brominating agent mixture feed should occur expeditiously, with consideration being given to the ability of the process equipment to handle the heat load from the exothermic process, the evolving HBr, and other process concerns.
  • the feed can occur over the shortest time period that will be allowed by the equipment without excursion outside of critical process parameters. Generally, it is anticipated that the feed period will be from 0.5 to 3 hours for a commercial-size plant. Shorter feed periods are expected for smaller scale processes.
  • the process of this invention occurs at a temperature within the range of from -20° C to 60° C and preferably within the range of from 0° C to 10° C. Most preferred temperatures are from 0° C to 5° C.
  • the pressure can be atmospheric, subatmospheric or superatmospheric.
  • a bromination catalyst say A1C1 3
  • A1C1 3 is suspended in essentially anhydrous bromochloromethane, to give an easily stirrable suspension.
  • the suspension is prepared in a glass-lined, stirred reactor and brought to a temperature within the range of from -5° C to 5° C. The mix is kept under an inert, dry atmosphere in the reactor.
  • a solution of a styrenic polymer and bromochloromethane is prepared and intimately mixed with a bromine stream to yield a homogenous mixture.
  • the mixture is fed into the stirred bromination catalyst suspension in the reactor.
  • the intimate mixing of the styrenic polymer solution and bromine can be accomplished in a number of ways.
  • the solution and bromine can be fed to a mixing device, e.g., a mixing nozzle, at the lower end of the diptube in the reactor which extends to a point below the suspension level.
  • the mixing device is designed to obtain the intimate mixing of the solution and bromine.
  • the mixing device acts to impart mixing energy, at the point of feed, to the intimate mixture and catalyst suspension.
  • Another technique for obtaining intimate mixing of the styrenic polymer solution and brominating agent is to use an exterior reactor loop having an in-line mixer, say an impingement mixer.
  • the use of an exterior reactor loop includes first charging the reactor with a bromination catalyst slurry, and suspension, and then withdrawing from the reactor a stream which is then fed to a mixer external of the reactor.
  • a mixture formed from at least bromine and styrenic polymer is also fed to the mixer to yield a second mixture which is formed from the two feeds to the mixer.
  • the second mixture is subsequently fed back to the reactor.
  • the stream withdrawn from the reactor will initially comprise the catalyst. After the second mixture is fed to the reactor and the process runs, the withdrawn stream will begin to comprise brominated polystyrene along with catalyst. As the process continues, the degree of bromination of the polystyrene will increase.
  • Reactor 1 is a stirred reactor and initially contains a suspension comprising catalyst and bromochloromethane.
  • Reactor discharge conduit 4 provides a stream from reactor 1 which is fed to pump 5.
  • Pump 5 pressurizes the stream so that it is fed with force via conduit 7 to impingement mixer 10.
  • Bromine is fed via conduit 20 to pump P, while, at the same time, a solution of polystyrene and bromochloromethane is fed via conduit 22 to pump P 2 .
  • Pumps 1 ⁇ and I? feed in-line mixer 11 to obtain an intimate mixture of bromine, polystyrene, and solvent.
  • This intimate mixture is fed to impingement mixer 10, wherein it is intimately mixed with the stream from reactor 1.
  • the discharge from impingement mixer 10 is fed via conduit 33 to reactor 1 through feed port 3.
  • the removal of contents from reactor 1 and their feed to impingement mixer 10 continues to occur until at least substantially all of the bromine and polystyrene/bromochloromethane solution have been fed.
  • the contents of reactor 1 change in composition during the bromine and bromochloromethane solution feeds.
  • the contents of reactor 1 comprise catalyst and solvent.
  • the reactor contents comprise and begin to become more rich in brominated polystyrene, some of which is underbrominated and some of which is of the degree of bromination sought.
  • the final bromination occurs. Removal of the reactor contents can continue to occur during the cook period to aid in mixing.
  • HBr HBr formed in the process is usually found in the head space above the reactor contents. It is preferred that the HBr be removed and passed to a water scrubber or stored as dry HBr. A dry, inert gas, say nitrogen, can be used as a pad over the reactor contents to minimize the presence of water therein.
  • the reactor in all cases, is preferably kept at a low temperature, e.g., from 0° C to 10° C, during the feed of the styrenic polymer and/or brominating feed, as the case may be, and most preferably from 0° C to 5° C. Also, after the feed is accomplished, the reactor is maintained for a cook period of from 0.5 to 6 hours and preferably from 0.5 to 1 hour.
  • the cook temperature is within the range of from 0° C to 10° C and preferably within the range of from 2° C to 5° C. The cook period serves to continue the bromination until the sought degree of bromination is obtained.
  • reaction parameters may be for a long period if the reaction parameters provide for mild bromination conditions during the bromine-polystyrene feed mixture or it may be for a short period if the parameters chosen provide for more severe bromination conditions.
  • the cook period can occur in the reactor.
  • the reaction mass can be treated with water, sodium sulfite, sodium gluconate and sodium hydroxide to deactivate the catalyst, kill any remaining brominating agent and to adjust the reaction mass pH.
  • the reaction mass is settled to obtain a two- phase reaction mass containing an organic phase, which contains, as a solute, the brominated styrenic polymer product, and an aqueous phase.
  • the aqueous phase is decanted and the remaining organic phase is stripped of its solvent component. It is most convenient to accomplish this strip by pouring the organic phase into boiling or near-boiling water. As the solvent is flashed off, the brominated styrenic polymer product forms a precipitate.
  • a surfactant such as dioctyl sulfosuccinate sodium salt
  • the amount of dioctyl sulfosuccinate used can be within the range of from 0.01 to 0.05 wt%, based upon the total weight of water and surfactant.
  • the precipitate can be recovered by any liquid-solid separation technique, e.g., filtration and centrifugation. The recovered precipitate is then dried.
  • a 0.910 g (6.82 mmol) portion of aluminum chloride was suspended (stirred at 250 rpm) in 190 g of dry (13 ppm water) bromochloromethane (BCM) in 1-L jacketed flask cooled to 0° C by circulating glycol bath.
  • BCM dry bromochloromethane
  • a 419.86 g portion of a 10.00 wt% solution of polystyrene (403.1/n mmol) in dry BCM was pumped at a constant rate of 8.46 g/min (8.13 mmol/min) to a jacketed, glycol- cooled mixing tee mounted on the reaction flask.
  • bromine was pumped at a constant rate of 6.09 g/min (38.1 mmol/min) to the same mixing tee where it combined with the polystyrene solution (feed mol ratio Br 2 /PS is 4.69) before dropping into the stirred catalyst suspension in the reaction flask.
  • the bromine feed was stopped after 30.0 min (1143.5 mmol) and the polystyrene solution feed was stopped after 49.6 min (overall mol ratio of Br 2 /PS is 2.84).
  • a rinse of 160 g of dry BCM was used for the polystyrene solution feed system to assure complete transfer of the polymer to the reaction flask.
  • the reaction temperature was maintained at 0° C - 5° C throughout the addition and subsequent 2 hr cook period.
  • the catalyst was deactivated by addition of 16.4 g of 10 wt% aqueous solution of sodium gluconate, and pH was adjusted to 14 by addition of 60.7 g of 10 wt% aqueous NaOH.
  • the reaction mixture was washed with 10 wt% aqueous sodium sulfite followed by a water wash.
  • the product was recovered from the organic phase by addition to vigorously stirred hot (90° C) water containing 0.02 wt% dioctyl sulfosuccinate sodium salt surfactant.
  • the solvent distilled from the hot water leaving a slurry of the brominated polystyrene product in water. After filtering, the powdery solid was rinsed with water and dried to constant weight in a vacuum oven (150° C/2 torr/5 hr). The dry solid weighed 127.08 g (95% yield). The product contained 69.6 wt% total Br and 3600 ppm hydrolyzable Br.
  • a Y-shaped mixing apparatus having a cooling jacket was equipped with 2 feed lines, each connected to a pump. One of the feed lines was for delivering bromine and the other was for delivering a PS and BCM solution.
  • Bromine (93.3 g, 31.3 ml or 0.583 mole), delivered at a rate of 1 ml/min (19.4 mmol/min), and a PS/BCM solution (22.4 g PS, 0.215 mole and 97 ml or 194 g of anhydrous BCM), delivered at 4 ml/min (7.17 mmol/min), were fed simultaneously from their respective feed lines into the cooled (5° C) Y-mixing apparatus.
  • the resultant intimate mixture from the mixing apparatus was then fed into a cooled (5° C) suspension of 0.45 g (2 wt% based on PS) of aluminum chloride in 49 ml (98 g) of anhydrous BCM. Evolved HBr was scrubbed by a caustic solution during the reaction. The feeds were complete in 35 minutes and the mixture was cooked for 2 hours at 5° C. After water and sodium sulfite washes, solid BrPS was isolated by precipitating from 500 ml of hot (90° C) water as described above. A total of 66 g of BrPS (97% yield) was obtained. The product contained 68.4 wt% total Br and 2800 ppm hydrolyzable Br.

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  • General Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
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  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)

Abstract

La présente invention concerne un polystyrène bromé thermiquement stable renfermant moins de 100 ppm de Cl- total, plus de 68 % en poids de brome et moins de 6000 ppm d'halogénure hydrolysable. Par rapport au polystyrène de départ, le polystyrène bromé présente peu ou pas de réticulation de polymère ou de clivage de chaîne.
EP98914612A 1997-05-07 1998-04-07 Procede de bromation des resines de polystyrene Withdrawn EP0980394A1 (fr)

Priority Applications (5)

Application Number Priority Date Filing Date Title
EP02028733A EP1293519B1 (fr) 1997-05-07 1998-04-07 Résines de polystyrène bromés
EP02028731A EP1293517B1 (fr) 1997-05-07 1998-04-07 Résines de polystyrène bromés
EP10001769.8A EP2189480B1 (fr) 1997-05-07 1998-04-07 Procédé de brome pour résines polystyréniques
EP10001768.0A EP2189479B1 (fr) 1997-05-07 1998-04-07 Procédé de brome pour résines polystyréniques
EP02028732.2A EP1293518B1 (fr) 1997-05-07 1998-04-07 Procédé de bromuration de résines de polystyrène

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US85246297A 1997-05-07 1997-05-07
US852462 1997-05-07
PCT/US1998/006996 WO1998050439A1 (fr) 1997-05-07 1998-04-07 Procede de bromation des resines de polystyrene

Related Child Applications (5)

Application Number Title Priority Date Filing Date
EP02028731A Division EP1293517B1 (fr) 1997-05-07 1998-04-07 Résines de polystyrène bromés
EP10001769.8A Division EP2189480B1 (fr) 1997-05-07 1998-04-07 Procédé de brome pour résines polystyréniques
EP02028733A Division EP1293519B1 (fr) 1997-05-07 1998-04-07 Résines de polystyrène bromés
EP02028732.2A Division EP1293518B1 (fr) 1997-05-07 1998-04-07 Procédé de bromuration de résines de polystyrène
EP10001768.0A Division EP2189479B1 (fr) 1997-05-07 1998-04-07 Procédé de brome pour résines polystyréniques

Publications (1)

Publication Number Publication Date
EP0980394A1 true EP0980394A1 (fr) 2000-02-23

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Application Number Title Priority Date Filing Date
EP98914612A Withdrawn EP0980394A1 (fr) 1997-05-07 1998-04-07 Procede de bromation des resines de polystyrene
EP02028732.2A Revoked EP1293518B1 (fr) 1997-05-07 1998-04-07 Procédé de bromuration de résines de polystyrène
EP10001769.8A Expired - Lifetime EP2189480B1 (fr) 1997-05-07 1998-04-07 Procédé de brome pour résines polystyréniques
EP10001768.0A Revoked EP2189479B1 (fr) 1997-05-07 1998-04-07 Procédé de brome pour résines polystyréniques
EP02028731A Expired - Lifetime EP1293517B1 (fr) 1997-05-07 1998-04-07 Résines de polystyrène bromés
EP02028733A Revoked EP1293519B1 (fr) 1997-05-07 1998-04-07 Résines de polystyrène bromés

Family Applications After (5)

Application Number Title Priority Date Filing Date
EP02028732.2A Revoked EP1293518B1 (fr) 1997-05-07 1998-04-07 Procédé de bromuration de résines de polystyrène
EP10001769.8A Expired - Lifetime EP2189480B1 (fr) 1997-05-07 1998-04-07 Procédé de brome pour résines polystyréniques
EP10001768.0A Revoked EP2189479B1 (fr) 1997-05-07 1998-04-07 Procédé de brome pour résines polystyréniques
EP02028731A Expired - Lifetime EP1293517B1 (fr) 1997-05-07 1998-04-07 Résines de polystyrène bromés
EP02028733A Revoked EP1293519B1 (fr) 1997-05-07 1998-04-07 Résines de polystyrène bromés

Country Status (5)

Country Link
EP (6) EP0980394A1 (fr)
JP (1) JP3882203B2 (fr)
CA (1) CA2286703C (fr)
DE (2) DE69832912T2 (fr)
WO (1) WO1998050439A1 (fr)

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US6518368B2 (en) 1996-06-14 2003-02-11 Albemarle Corporation Brominated polystyrene having improved thermal stability and color and process for the preparation thereof
US5637650A (en) 1996-06-14 1997-06-10 Ferro Corporation Brominated polysytrene having improved thermal stability and color and process for the preparation thereof
US6232393B1 (en) 1996-09-26 2001-05-15 Albemarle Corporation Polymers flame retarded with brominated polystyrenic resins
US6235831B1 (en) 1996-09-26 2001-05-22 Albemarle Corporation Polymer compositions containing brominated polystyrenic resins
US6232408B1 (en) 1996-09-26 2001-05-15 Albemarle Corporation Brominated polstyrenic resins
US6326439B1 (en) 1996-09-26 2001-12-04 Albemarle Corporation Process for brominating polystyrenic resins
US6521714B2 (en) 1996-09-26 2003-02-18 Albemarle Corporation Brominated polystyrenic resins
US6235844B1 (en) 1996-09-26 2001-05-22 Albemarle Corporation Brominated polystyrenic resins
JP4450510B2 (ja) * 1998-09-10 2010-04-14 アルベマール・コーポレーシヨン 改良臭素置換ポリスチレン系樹脂およびそれらの使用
CN100551659C (zh) 2004-05-20 2009-10-21 雅宝公司 制成粒状的溴化阴离子苯乙烯系聚合物及其制备和应用
CA2614096C (fr) 2005-06-30 2014-08-12 Albemarle Corporation Polymeres styrene bromes et leur preparation
ATE478897T1 (de) * 2005-12-21 2010-09-15 Albemarle Corp Herstellung brominierter styren-polymere oder - harze
EP1963377B1 (fr) 2005-12-21 2016-08-10 Albemarle Corporation Polymères styréniques anioniques bromés et leur préparation
EP2044133B1 (fr) 2006-07-20 2015-01-28 Albemarle Corporation Technologie de traitement pour la récupération de polymères styréniques bromés à partir de mélanges réactifs dans lesquels ils sont formés et/ou conversion de ces mélanges en granules ou en pastilles
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Publication number Publication date
DE69832912D1 (de) 2006-01-26
EP1293518A3 (fr) 2003-11-26
JP2001523297A (ja) 2001-11-20
CA2286703C (fr) 2010-06-22
EP2189480A1 (fr) 2010-05-26
DE69832912T2 (de) 2006-09-21
EP2189480B1 (fr) 2014-12-03
EP1293518A2 (fr) 2003-03-19
JP3882203B2 (ja) 2007-02-14
EP1293517A2 (fr) 2003-03-19
DE69832913D1 (de) 2006-01-26
EP2189479A1 (fr) 2010-05-26
EP1293519B1 (fr) 2005-12-21
EP2189479B1 (fr) 2014-12-24
EP1293517A3 (fr) 2003-11-26
EP1293519A3 (fr) 2003-11-19
CA2286703A1 (fr) 1998-11-12
EP1293519A2 (fr) 2003-03-19
WO1998050439A1 (fr) 1998-11-12
DE69832913T2 (de) 2006-09-14
EP1293517B1 (fr) 2005-12-21
EP1293518B1 (fr) 2014-12-24

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