WO1998051714A1 - N-ethylhydroxylamine en tant qu'agent inhibiteur de la polymerisation des radicaux libres - Google Patents

N-ethylhydroxylamine en tant qu'agent inhibiteur de la polymerisation des radicaux libres Download PDF

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Publication number
WO1998051714A1
WO1998051714A1 PCT/US1998/009041 US9809041W WO9851714A1 WO 1998051714 A1 WO1998051714 A1 WO 1998051714A1 US 9809041 W US9809041 W US 9809041W WO 9851714 A1 WO9851714 A1 WO 9851714A1
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Prior art keywords
eha
shortstopping
free radical
monomer
ethylhydroxylamine
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Application number
PCT/US1998/009041
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English (en)
Inventor
Patrick E. Brutto
Thomas H. Marman
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Angus Chemical Company
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Publication date
Application filed by Angus Chemical Company filed Critical Angus Chemical Company
Priority to AU72819/98A priority Critical patent/AU7281998A/en
Publication of WO1998051714A1 publication Critical patent/WO1998051714A1/fr

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    • 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
    • C08F2/00—Processes of polymerisation
    • C08F2/38—Polymerisation using regulators, e.g. chain terminating agents, e.g. telomerisation
    • C08F2/42—Polymerisation using regulators, e.g. chain terminating agents, e.g. telomerisation using short-stopping agents
    • 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
    • C08F36/00—Homopolymers and copolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds
    • C08F36/02—Homopolymers and copolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds the radical having only two carbon-to-carbon double bonds
    • C08F36/04—Homopolymers and copolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds the radical having only two carbon-to-carbon double bonds conjugated

Definitions

  • N-ETHYLHYDROXYLAMINE AS A SHORTSTOPPING AGENT FOR FREE RADICAL POLYMERIZATION
  • This invention is related to the general field of free radical polymerization. More particularly, it relates to what are called “shortstopping agents", which are used to prevent a free radical polymerization reaction from proceeding to completion.
  • free radical polymerization is the emulsion polymerizations used in making elastomers such as styrene-butadiene rubber (SBR), butadiene rubber (BR), and acrylonitrile-butadiene rubber (NBR). These polymerizations are carried out using “hot” and “cold” reactions (referring to the temperature of the reaction).
  • a free radical initiator is used in both types, although they are usually different initiators, to generate the free radicals which start the reactions.
  • the growing polymer regenerates free radicals at the ends of the polymer chain.
  • the properties of the polymers produced vary with the degree of polymerization i.e. the percentage of the monomers converted. It is generally desirable to stop the polymerization at a predetermined degree of conversion. For example, when making SBR using a "cold" reaction, it is common to stop the polymerization at about 60-65 % conversion.
  • At least three areas are of concern when employing a shortstopping agent, in addition to primary function i.e. whether it is effective in stopping a free radical polymerization.
  • the proposed shortstopping agent must be able to stop the reaction, but it should not be so readily removed from the reaction mixture as to permit the polymerization to proceed after the residual monomer is stripped off. If a free radical polymerization reaction is stopped short of completion, a large amount of unreacted monomer remains. This is typically removed from the polymer by steam stripping, recovered, and recycled. If the shortstopping agent is too volatile it vaporizes with the unreacted monomer and too little remains with the polymer so that further polymerization can occur.
  • the shortstopping agent will be recovered with the monomer and will suppress polymerization of the recycled monomer. This will make it necessary to add extra initiator to start the reaction when the recycled monomer is reused.
  • the shortstopping agent is not volatile, and does not vaporize with the monomer, excessive polymerization may occur in the recovery equipment. This is often called "popcorn" polymer. It adheres to the monomer recovery equipment, making it necessary to open and clean it frequently, which is clearly undesirable.
  • the second area of concern is whether the shortstopping agent is corrosive.
  • nitrosamines The third area of concern is the formation of nitrosamines. Some of these materials have been found to be carcinogenic in laboratory animal testing and they are regulated in several countries. They can be formed by the reaction of amines with nitrosating agents such as NO x or sodium nitrite. Hydroxyl amines are one class of shortstopping agents. In US Patent 3,222,334
  • N,N' dialkylhydroxylamines are disclosed to be useful shortstopping agents.
  • One example of such materials is N,N'-diethylhydroxylamine (DEHA).
  • DEHA N,N'-diethylhydroxylamine
  • This compound may also be used as an agent to suppress polymer growth in residual polymer left after cleaning the equipment used to carry out free radical polymerizations, according to Japanese Kokai 64-13041.
  • N-monoalkylhydroxylamines have been suggested also as shortstopping agents, particularly isopropylhydroxylamine (IPHA) in US Patent 5,384,372. It was shown that IPHA has the advantage of not making nitrosamines, which the other materials tested did produce. They included DEHA plus sodium dimethyl thiocarbamate, hydroxylamine, and hydroxylamine sulfate.
  • shortstopping agents have been disclosed, alone or in combination with the hydroxylamines. Examples include sodium polysulfide and sodium dimethyl dithiocarbamate. IPHA has been suggested as a shortstopping agent in a mixture with sodium polysulfide in US Patent 5,504, 168. Again, the ability to avoid making nitrosamines was important to the patentees. Both mono and dialkylhydroxylamines were suggested in US Patent 3,296,177 as shortstopping agents, but in the form of the bisoxalate salts, made by reacting the hydroxylamines with oxalic acid. Monoethylhydroxylamine (EHA) has not been disclosed as a shortstopping agent for free radical polymerizations as far as the present inventor is aware.
  • EHA Monoethylhydroxylamine
  • EHA monoethylhydroxylamine
  • the invention is a method of stopping free radical polymerizations before completion by adding as a shortstopping agent, N-ethylhydroxylamine or salts thereof (both being included within the acronym EHA).
  • EHA N-ethylhydroxylamine or salts thereof (both being included within the acronym EHA).
  • the EHA may be present in amounts of up to about 2 parts by weight for each 100 parts by weight of the initial amount of monomer (2 phm).
  • the EHA will be added in an amount within the range of about 0.01 to 2.0 phm, more preferably in the range of about 0.05 to 0.1 phm.
  • EHA could be mixed with other shortstopping agents including IPHA, DEHA, sodium polysulfide, and sodium dimethyldithiocarbamate.
  • EHA may be used as a shortstopping agent for any free radical polymerization.
  • it may be used for polymerization of conjugated diolefins including 1,3 butadiene, 2-chlorobutadiene, 1 ,3 isoprene, piperylene, chloroprene and related compounds.
  • the shortstopping agent of the invention may also be used for polymerizations in which copolymers of conjugated diolefins and monoolefms are being made, such as copolymers of the conjugated diolefins mentioned above with monoolefms such as styrene, vinyl naphthalene, acrylic acid, methacrylic acid, acrylonitrile, and related compounds.
  • polymerizations using free radical reactions of ethylenically unsaturated monomers also may use the shortstopping agent of the invention.
  • monomers in such polzmerizations include vinyl halides, acrylates, acrylamides, vinyl esters and related compounds.
  • the invention is the use of N-ethylhydroxylamine or salts thereof (EHA) as a shortstopping agent for free radical polymerizations, such as those mentioned above where conjugated diolefins are polymerized alone or in combination or copolymerized with monoolefms.
  • EHA N-ethylhydroxylamine or salts thereof
  • the invention is an improvement in the emulsion polymerization of conjugated dioefins, optionally including monoolefms, comprising adding an effective amount of EHA when predetermined conversion has been reached.
  • Such emulsion polymerizations are usually carried out at elevated temperatures of about 50 to 70 °C (hot reactions) or at below ambient temperatures of about 5 to 15°C (cold reactions). Typically, such reactions are not permitted to continue until all the monomer(s) has been consumed.
  • the properties of the polymer change as the molecular weight increases, as might be expected. The most desirable properties are found in polymers made by only partial conversion of the monomer(s).
  • shortstopping agents to the reacting mixture to prevent the polymerization from continuing. As discussed above, many shortstopping agents have been suggested and used in commercial practice. They are added at a suitable time so that the reaction is stopped at the desired percentage conversion of the monomer(s), but they should have other characteristics as well.
  • a shortstopping agent should not only stop the polymerization reaction at the desired percentage conversion, but it should have no deleterious effect on the polymer itself, such as adding color. In addition, it should not be corrosive so that the polymerization equipment is not damaged and the polymer contaminated by corrosion products.
  • Some of the otherwise effective shortstopping agents are known to be corrosive, such as sodium polysulfide.
  • a problem of more recent concern relating to the selection of a shortstopping agent is their potential for reacting with NO x and nitrates to form nitrosamines. Such materials have been found to be carcinogenic in laboratory tests and have been regulated in certain countries. Therefore, use of shortstopping agents which may form nitrosamines is to be avoided.
  • IPHA isopropylhydroxylamine
  • the presence of the shortstopping agent in the recovered monomer(s) is not desirable, since it will be recycled and hinder the subsequent polymerization reaction when it is removed.
  • the shortstopping agent remain with the polymer, but that enough of the agent go off with the monomer(s) so that it suppresses popcorn polymer formation in the equipment used to recover the monomer(s).
  • Such polymerization is a problem in commercial production since the equipment must be taken out of service periodically for cleaning.
  • the cleaning is not complete, residual polymer can be a source of continued growth when the equipment is returned to service.
  • Hydroxylamines and their salts have been used as shortstopping agents, particularly N,N' -dialkylhydroxylamines, such as diethylhydroxylamine (DEHA).
  • DEHA diethylhydroxylamine
  • dialkylhydroxylamines are able to form nitrosamines and consequently, they are not always acceptable where formation of nitrosamines is regulated. Hydroxylamine is shown to produce nitrosamines in US 5,384,372.
  • IPHA Isopropylhydroxylamine
  • EHA monoethylhydroxylamine
  • EHA has been found to be relatively non-corrosive and more water soluble than IPHA and it is expected not to produce nitrosamines.
  • the amount of EHA needed to shortstop free radical polymerizations has been found to be similar to other shortstopping agents. Amounts up to about 2 parts by weight for each 100 parts by weight of the initial monomer(s) may be used (abreviated as “phm” hereafter). Preferably, about 0.01 to 2.0 phm will be used, more preferably about 0.05 to 0.1 phm.
  • the EHA will be added to the reacting mixture at a suitable time so that the desirable percentage conversion will be achieved. Typically, this is about 50 to 70 % conversion of the initial monomer(s).
  • N-ethylhydroxylamine or its salts such as the hydrochloride, acetate, or sulfate may be used.
  • the salts of hydroxylamines have often been prepared because of their more desirable physical properties.
  • EHA could be mixed with other shortstopping agents such as IPHA,
  • EHA effectiveness of EHA as a shortstopping agent was examined by carrying out cold polymerization of styrene and butadiene monomers.
  • the reaction mixture given in Table A below was prepared and placed in 8oz (227mL) glass bottles. The bottles were tumbled continuously in a water bath held at 5°C . The reaction proceeded with samples being taken at two hour intervals to determine the extent of the polymerization reaction.
  • the EHA was added at a time which corresponded to about 60 % conversion. The amount added was varied to determine the optimum amount needed to shortstop the polymerization. However, the reaction should be fully stopped and in each case the emulsion was aged for a week at 50°C to determine whether further polymerization occurred.
  • the percentage conversion was measured by withdrawing a small amount of the emulsion from the bottle with a syringe, drying the sample at 150-175°C and then weighing the residue. A correction was made for non-volatile materials expected to be present, such as potassium hydroxide and potassium chloride. The results shown in Table B record the results of these tests.
  • Example 2 As has been already explained, the volatility of a shortstopping agent has an effect on the subsequent polymerization of the recovered polymer, on the formation of popcorn polymer in the equipment used to recover the unreacted monomer(s), and on the amount of free radical inititator required.
  • a closed-loop distillation apparatus was used to compare the volatility of EHA with other shortstopping agents.
  • a 1 % by weight solution of each shortstopping agent was prepared in deionized water. It was boiled at 70°C under a reduced pressure of 265 mmHg absolute, which approximates the conditions under which unreacted monomers are stripped from polymerized mixtures after a shortstopping agent has been added.
  • Example 4 The corrosivity of a 1 wt. % solution of EHA in chlorinated tap water (approximately 125 wppm total hardness) was determined by immersing half of test coupons of C1010 mild steel, 304 stainless steel, and 316 stainless steel in separate solutions. After four weeks in sealed containers having an atmosphere of either air or nitrogen at a temperature of 50°C the coupons were removed from the jars, acid cleaned, and then weighed to determine how much metal had been removed. The results are reported in Table F below.
  • EHA is similar to IPHA in corrosivity to C 1010 steel and that both are less corrosive than DEHA. SP, SDD, and tap water were still more corrosive. Both of the stainless steels were resistant to corrosion by any of the shortstopping agents.

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

Abstract

Nouvel agent inhibiteur conçu pour arrêter la polymérisation des radicaux libres et consistant en N-éthylhydroxylamine ou certains de ses sels (EHA). Il est aussi efficace que les hydroxylamines apparentées, mais beaucoup moins volatil, de sorte qu'il tend à rester avec le polymère plutôt que d'en être pratiquement supprimé quand on enlève et qu'on récupère le monomère ou les monomères n'ayant pas subi de réaction. EHA n'est pas corrosif pour les métaux utilisés dans des installations commerciales de polymérisation d'émulsions et on pense qu'il ne laissera apparaître aucun produit secondaire indésirable de nitrosamine.
PCT/US1998/009041 1997-05-16 1998-05-04 N-ethylhydroxylamine en tant qu'agent inhibiteur de la polymerisation des radicaux libres WO1998051714A1 (fr)

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1083185A1 (fr) * 1999-09-09 2001-03-14 Atofina Chemicals, Inc. Compositions pour arrêter une polymérisation radicalaire en émulsion
EP1132408A1 (fr) * 2000-03-07 2001-09-12 Atofina Chemicals, Inc. Compositions d'arrêt de polymérisations en émulsion par radicaux libres et latex stables ainsi préparés
WO2002038617A1 (fr) * 2000-11-07 2002-05-16 Dow Global Technologies Inc. Procede d'interruption de processus de polymerisation dans la fabrication de caoutchoucs synthetiques
WO2013110865A1 (fr) 2012-01-24 2013-08-01 Arkema France Procede de preparation de polymeres halogenes
WO2013188632A1 (fr) * 2012-06-14 2013-12-19 Dow Global Technologies Llc Composés alkyl hydroxylamines et leur utilisation pour arrêter des polymérisations par radicaux libres
WO2014052212A1 (fr) * 2012-09-28 2014-04-03 Dow Global Technologies Llc Composés d'alkylhydroxylamine et leur utilisation pour l'interruption de polymérisations par radicaux libres
JP2015519466A (ja) * 2013-06-13 2015-07-09 アンガス ケミカル カンパニー アルキルヒドロキシルアミン化合物およびフリーラジカル重合を重合停止させるためのそれらの用途

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US3296177A (en) * 1964-11-13 1967-01-03 Pennsalt Chemicals Corp Stopping agents for synthetic rubber polymerization
US3341487A (en) * 1964-07-21 1967-09-12 Pennsalt Chemicals Corp Process for stopping emulsion polymerizations by the addition of dithiocarbamate salts and alkyl hydroxyl amines
US5384372A (en) * 1994-03-30 1995-01-24 The Goodyear Tire & Rubber Company Shortstopping of free radical polymerizations
US5396004A (en) * 1992-10-21 1995-03-07 Betz Laboratories, Inc. Compositions and methods for inhibiting vinyl aromatic monomer polymerization

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3341487A (en) * 1964-07-21 1967-09-12 Pennsalt Chemicals Corp Process for stopping emulsion polymerizations by the addition of dithiocarbamate salts and alkyl hydroxyl amines
US3296177A (en) * 1964-11-13 1967-01-03 Pennsalt Chemicals Corp Stopping agents for synthetic rubber polymerization
US5396004A (en) * 1992-10-21 1995-03-07 Betz Laboratories, Inc. Compositions and methods for inhibiting vinyl aromatic monomer polymerization
US5384372A (en) * 1994-03-30 1995-01-24 The Goodyear Tire & Rubber Company Shortstopping of free radical polymerizations

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001122913A (ja) * 1999-09-09 2001-05-08 Atofina Chemicals Inc 遊離基乳化重合のショートストップのためのニトロソアミン阻害性組成物
KR100730904B1 (ko) * 1999-09-09 2007-06-22 알케마 인코포레이티드 유리 라디칼 유화 중합을 연쇄정지시키기 위한 니트로사민 억제 조성물
EP1083185A1 (fr) * 1999-09-09 2001-03-14 Atofina Chemicals, Inc. Compositions pour arrêter une polymérisation radicalaire en émulsion
EP1132408A1 (fr) * 2000-03-07 2001-09-12 Atofina Chemicals, Inc. Compositions d'arrêt de polymérisations en émulsion par radicaux libres et latex stables ainsi préparés
WO2002038617A1 (fr) * 2000-11-07 2002-05-16 Dow Global Technologies Inc. Procede d'interruption de processus de polymerisation dans la fabrication de caoutchoucs synthetiques
US9221933B2 (en) 2012-01-24 2015-12-29 Arkema France Process for preparing halogenated polymers
WO2013110865A1 (fr) 2012-01-24 2013-08-01 Arkema France Procede de preparation de polymeres halogenes
WO2013188632A1 (fr) * 2012-06-14 2013-12-19 Dow Global Technologies Llc Composés alkyl hydroxylamines et leur utilisation pour arrêter des polymérisations par radicaux libres
CN104364276A (zh) * 2012-06-14 2015-02-18 陶氏环球技术有限责任公司 烷基羟胺化合物以及它们在速止自由基聚合中的应用
US9234052B2 (en) 2012-06-14 2016-01-12 Angus Chemical Company Alkyl hydroxylamine compounds and their use for shortstopping free radical polymerizations
WO2014052212A1 (fr) * 2012-09-28 2014-04-03 Dow Global Technologies Llc Composés d'alkylhydroxylamine et leur utilisation pour l'interruption de polymérisations par radicaux libres
US9309331B2 (en) 2012-09-28 2016-04-12 Angus Chemical Company Alkyl hydroxylamine compounds and their use for shortstopping free radical polymerizations
JP2015519466A (ja) * 2013-06-13 2015-07-09 アンガス ケミカル カンパニー アルキルヒドロキシルアミン化合物およびフリーラジカル重合を重合停止させるためのそれらの用途

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