CA2204904A1 - Oxidation of sulfur-containing polymers by no2/n2o4 - Google Patents
Oxidation of sulfur-containing polymers by no2/n2o4Info
- Publication number
- CA2204904A1 CA2204904A1 CA002204904A CA2204904A CA2204904A1 CA 2204904 A1 CA2204904 A1 CA 2204904A1 CA 002204904 A CA002204904 A CA 002204904A CA 2204904 A CA2204904 A CA 2204904A CA 2204904 A1 CA2204904 A1 CA 2204904A1
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- sulfur
- poly
- oxidation
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G75/00—Macromolecular compounds obtained by reactions forming a linkage containing sulfur with or without nitrogen, oxygen, or carbon in the main chain of the macromolecule
- C08G75/02—Polythioethers
- C08G75/0204—Polyarylenethioethers
- C08G75/0286—Chemical after-treatment
- C08G75/0295—Modification with inorganic compounds
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G75/00—Macromolecular compounds obtained by reactions forming a linkage containing sulfur with or without nitrogen, oxygen, or carbon in the main chain of the macromolecule
- C08G75/02—Polythioethers
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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)
- Inorganic Chemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Polymers With Sulfur, Phosphorus Or Metals In The Main Chain (AREA)
- Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
Abstract
The invention concerns a process for the oxidation of a sulphurous polymer in which the solid polymer is brought into contact with liquid or gaseous N2O4.
The resultant polymer is suitable for preparing highly stressed functional parts.
The resultant polymer is suitable for preparing highly stressed functional parts.
Description
. ~ CA 02204904 l997-0~-08 ' Description Oxidation of sulfur-cont~;n;ng polymers by NO2/N2O4 The in~ention relates to the oxidation of sulfur-con-t~;n; ng polymers by NO2/N2O4 as oxidizing agent.
Sulfur-cont~in;ng polymers such as poly(arylene thio-ethers) have long been known. Because of their high heat distortion temperature and good chemical resistance, these polymers are used for highly stressed components.
However, in some applications, higher material require-ments are made. Specifically, an increase in the glass transition temperature of the polymers is frequently desirable. It is described that by a polymer-analogous oxidation of poly(phenylene sulfide) in acetic acid by concentrated nitric acid for 24 hours at 0 to + 5~C, a conversion to poly(phenylene sulfoxide) is said to be possible (US 3,303,007). "Polymer-analogous" means the con~ersion of one polymer into another. However, the properties quoted for the polymer formed indicate that no polymer having a sulfur/oxygen ratio of 1 to 1 was obtained, since otherwise the values for the heat distor-tion temperature would have to be higher. Disadvantages of the process described are firstly the long reaction time necessary, secondly the possibility of electrophilic addition and thirdly the acid attack o~ the strong mineral acid on the thioether bond in the case of long reaction times (degradation reactions).
It is known that NO2 and its dimer N2O4 are in chemical equilibrium with each other (~ollemann-Wiberg, Lehrbuch der Anorganischen Chemie, ~Textbook of inorganic chemistry], Walter de Gruyter & Co. Berlin 1964, 70th Edition, pp. 238/239).
Sulfur-cont~in;ng polymers such as poly(arylene thio-ethers) have long been known. Because of their high heat distortion temperature and good chemical resistance, these polymers are used for highly stressed components.
However, in some applications, higher material require-ments are made. Specifically, an increase in the glass transition temperature of the polymers is frequently desirable. It is described that by a polymer-analogous oxidation of poly(phenylene sulfide) in acetic acid by concentrated nitric acid for 24 hours at 0 to + 5~C, a conversion to poly(phenylene sulfoxide) is said to be possible (US 3,303,007). "Polymer-analogous" means the con~ersion of one polymer into another. However, the properties quoted for the polymer formed indicate that no polymer having a sulfur/oxygen ratio of 1 to 1 was obtained, since otherwise the values for the heat distor-tion temperature would have to be higher. Disadvantages of the process described are firstly the long reaction time necessary, secondly the possibility of electrophilic addition and thirdly the acid attack o~ the strong mineral acid on the thioether bond in the case of long reaction times (degradation reactions).
It is known that NO2 and its dimer N2O4 are in chemical equilibrium with each other (~ollemann-Wiberg, Lehrbuch der Anorganischen Chemie, ~Textbook of inorganic chemistry], Walter de Gruyter & Co. Berlin 1964, 70th Edition, pp. 238/239).
2 NO2 s N2O~ + 13.9 kcal CA 02204904 1997-0~-08 Depending on the temperature and concentration, a greater or lesser portion of the NO2 is present as N2O4. At a concentration of more than 99 % NO2/N2O4 in a closed system, at 27~C 80 % of the nitrogen dioxide is present 5 as N2O4 and at 50~C 60 % is still present as N2O4. Not until 135~C is only 1 % N204 still present.
The object of the invention is to develop processes for the oxidation of sulfur-cont~;n;ng polymers such as poly(arylene sulfides) which require substantially shorter reaction times at mild reaction temperatures. The use of poly(arylene sulfides) having relatively high molecular weights as starting material is also desirable.
The object was achieved by the use of NO2/N204 as oxidizing agent, the proportion of N2O4 being determined by the reaction temperature (see above).
The e~uilibrium system NO2/N2O4 used for the oxidation is termed N204 below.
The invention relates to a process for the oxidation of a sulfur-cont~;n;ng polymer in which the sulfur-con-2 0 t~; n; ng polymer is brought into contact with NO2 or N2O4.
The oxidation of the sulfur-cont~;n;ng polymer N2O4 according to the invention leads with high selec-tivity to the formation of sulfoxide bridges. This is all the more surprising since N2O4 is an extremely strong oxidizing agent. By appropriate use of the amount of N2O4 and the choice of reaction duration it is possible either to convert the sulfur bond completely into the sulfoxide bond or to achieve any desired partial oxidation of the sulfur bonds in the sulfur-cont~;n;ng polymer. A hetero-geneous oxidation or partial oxidation of the sulfur-cont~;n;ng polymer can proceed fully in and right through a material or only at the surface of a material. A
heterogenous oxidation right through is achieved all the more easily, the finer is the material. Particularly , CA 02204904 1997-0~-08 suitable materials for oxidation right through are ultrathin or ultrafine particles, fibers, films, moldings or coatings. In this case a highly uniform oxidation is achieved. Ultrathin or ultrafine denotes a diameter or a thickness of up to 50 ~m, preferably 1 to 30 ~m, in particular 5 to 25 ~m. The invention therefore further relates to particles, fibers, films, moldings or coatings o~ poly(arylene sulfoxide) ha~ing a diameter or a thick-ness of up to 50 ~m.
The ultrathin or ultrafine poly(arylene sulfoxide) parts can be produced by oxidation of appropriately ~;m~ncioned poly(arylene sulfide) parts and feature a very high homogeneity of composition or a very uniform degree of oxidation, by which means, for example, the mechanical, physical and chemical properties are improved. Ultrathin or ultrafine poly(arylene sulfoxide) parts show, for example, because of their homogeneity, improved heat stability and chemical resistance.
For example, woven fabrics or no~woveLls made of ultrathin poly(arylene sulfoxide) fibers are suitable for pro~ ;ng filters for high-temperature applications.
Ultrafine particles of poly(arylene sulfoxide) are particularly suitable for producing foamed poly(arylene ~ulfide). Poly(arylene sulfoxide) as a blowing agent for poly(arylene sulfide) is described in German Patent Application P 44 28 737.2 of 15th August 1994 with the title "Poly(arylene sulfide) foams and process for their production", which is incorporated herein by reference.
The expression sulfur-contA;n;ng polymers includes polymer~ which contain at least one arylene thioether unit (-AR-S-; Ar: arylene) or an aliphatic thioether unit (-Alk-S-; Alk: alkylene), eg. poly(arylene thioethers) or polysulfides. The arylene groups can comprise m~nsnnclear or polynuclear aromatics. The arylene groups comprise at least one 5- or 6-membered ring which can contain one or . CA 02204904 1997-0~-08 more heteroatoms and can be unsubstituted or substituted.
Heteroatoms are, eg., nitrogen or oxygen, substituents are, eg. linear or branched alkyl groups. The sulfur-containing polymers can also contain, apart from sulfur bridges (-S-), sulfoxide groups (-SO-) or sulfone groups (-SO2-). Arylenes are, for example, phenylene, biphenyl-ene (-C6X4-C6H4-) or naphthylene which can be monosubsti-tuted ~r polysubstituted. Substituents are, for example, straight-chain, cyclic or branched C1-C20-hydrocarbon radicals, such as C1-C10-alkyl radicals, eg. methyl, ethyl, n-propyl, isopropyl, n-butyl, t-butyl or n-hexyl, or C6-C14-aryl radicals, eg. phenyl or naphthyl; halide, sulfonic acid, amino, nitro, cyano, hydroxyl or carboxyl groups.
Preferred sulfur-containing polymers are poly(arylene thioethers), also termed poly(arylene sulfide), in particular poly(phenylene sulfide).
In the oxidation of poly(arylene sulfide) by N2O4, poly(arylene sulfoxides) are formed. Poly(arylene sul-foxides) are polymers which contain at least one arylenesulfoxide unit (-Ar-SO-; Ar = arylene radical, SO = sulfoxide group).
Poly(arylene sulfides), in particular poly(phenylene sulfide), may be prepared on the basis of the reaction of dihalogenated aromatics with sodium sulfide according to ~n~o~ns and HILL. Poly(phenylene sulfide) and its prepa-ration are described in ''u~ nn~s Encyclopedia of Industrial Chemistry, Volume A21, B. Elvers, S. Hawkins and G. Schulz (Eds.), VCH, Weinheim-New York 1992, pp.
463-472), which is incorporated herein by reference. The synthesis of sulfone-cont~;n;ng poly(arylene sulfides) is described in Chimia 28 (1974) 567, which is incorporated herein by reference.
A suitable sulfur-cont~;n;ng polymer is, for example, one ha~ing a mean molecular weight Mw of 4000 to 400,00Q, . CA 02204904 1997-0~-08 - preferably 10,000 to 150,000, in particular 25,000 to 100,000, determined by GPC.
The mean particle size D50 of the polymers used is generally in the range of about 5 x 10-7 to about 5 x 10-2 m, preferably about 10-5 to about 10-3 m, and in particular about 10-5 to about 2 x 10~4m.
The sulfur-cont~in;ng polymer is generally present in solid form at the beg;nn;ng of the oxidation reaction. It can also be used in dissolved form or in suspension.
When dissolved sulfur-cont~;n;ng polymer is used, the reaction with N2O4 is a homogeneous oxidation reaction.
When solid or suspended sulfur-cont~;n;ng polymer is used, the reaction with N204 is a heterogeneous oxidation reaction.
The suspension medium for the sulfur-cont~;n;ng polymer is generally a chemically inert sol~ent. Thus, liquids can be used in which the reaction product is insoluble, for example acetic acid, l,1-dichloroethane, dichloro-methane or 1,1,2-trichloro-1,2,2-trifluoroethane. Xow-ever, it is also possible to use liquids in which theoxidation product dissolves, such as dichloroacetic acid, trichloroacetic acid or trifluoroacetic acid.
The reaction temperatures are generally in the range from minus 40 to + 100~C, preferably from minus 5 to 80~C. The reaction time required depends on the supply of N2O4 and the type of reactor chosen and is generally 1 minute to 5 hours, preferably 15 minutes to 120 minutes, and in particular 15 minutes to 60 minutes. When the reaction conditions are optimized, it is possible to achieve reaction times below one minute.
The oxidation according to the invention is carried out, for example, in an atmosphere comprising N2O4 having a concentration greater than 40 mol %, preferably greater CA 02204904 1997-0~-08 than 60 mol %, and in particular greater than 70 mol %.
The reaction can be carried out in a reactor whose temperature can be controlled, statically or with stir-ring, at atmospheric pressure or under pressure.
Oxidation by N204 can be performed by liquid N204.
In the oxidation of a sulfide group to sulfoxide, N204 is reduced to N203. By a subsequent reaction with atmos-pheric oxygen, this N203 can be reoxidized back to N204 and thus reco~ered, so that the process described here can be carried out highly cost-effectively.
The reoxidation of N203 to N204 can also take place, for example, in a loop reactor in which the N204 is circu-lated; in the reaction loop it oxidizes the sulfur-containing polymer and in the return loop is brought into contact with oxygen and reoxidized to N204.
It is also possible to carry out the reaction with substoichiometric amounts of N204 if oxygen or air is blown through the reaction solution. In this case, the N203 formed in the reaction is immediately reoxidized to N204 in the reaction mixture and can thus oxidize a plurality of sulfide groups to sulfoxide. The N204 used under such reaction conditions acts as an oxygen transfer agent (catalyst). Consequently, the degree of oxidation of the polymer can be set specifically by the reaction duration.
After oxidation is completed, the N204 can be expelled from a reactor, eg. from a solution or suspension, by a vigorous air stream or oxygen stream and condensed out in a cooling apparatus and thus recovered.
In addition, it is possible to carry out the reaction with a substoichiometric amount of N204 in an autoclave with an oxygen overpressure. The N203 formed in the oxidation is here immediately reoxidized to N204.
. CA 02204904 1997-0~-08 When a sol~ent or suspension medium is used, the reaction can be carried out either discontinuously in a stirred tank (batch process) or in a continuous reactor, for example a reactor cascade, comprising a plurality of pots, or a flow tube. When a reactor cascade is used, the reaction products can, for example, be combined with the solvent or dispersion medium in the first cascade pot, the reaction and oxygen addition can take place in the second cascade pot and the N204 can be expelled when oxidation is completed in a third cascade pot.
The N204 (after the reoxidation with oxygen) and, if appropriate, the solvent or suspension medium, can be used for further reactions either in a discontinuous or in a continuous reaction course, so that in the oxidation reaction all components can be used again and no residues cont~m;n~ting the environment occur.
The degree of oxidation of the polymer which can be achieved depends on the precise reaction conditions.
When air or oxygen is added during the reaction, because of the immediate reoxidation of the N203 formed to N204, higher degrees of oxidation can be achieved than corres-pond to the stoichiometry of the N204 used.
The oxidation products of the reaction of N204 with a sulfur-contA;n;ng polymer are in many cases soluble in dichloroacetic acid and can be processed therefrom in conventional proce~ses.
The oxidized or partially oxidized sulfur-contA;n;ng polymers obtained according to the invention may either be processed thermoplastically or may be further pro-cessed, for example, by customary sintering processes,but this is dependent on their melting points. The first group, i.e. the compounds which can be processed thermo-plastically, can be converted into moldings and func-tional components by processing methods customary for . , CA 02204904 1997-0~-08 ~.
thermoplastics, eg. injection molding or extrusion. The molding compounds can also contain known pulverulent fillers such as chalk, talc, clay, mica and/or fibrous reinforcing agentsr such as glass fibers and carbon fibers, whiskers, and other conventional additives and processing aids, eg. lubricants, release agents, antioxi-dants and W stabilizers. Such components are used a~
heavy-duty functional components, for example in aircraft and automobile construction and in chemical plant con-struction.
The second group, ie. the polymers which can be processedby sintering processes, are used in functional components having high temperature and chemical stress.
The compounds obtained according to the invention can, moreover, also be added in powder mixtures to other high-temperature thermoplastics, eg. PPS or liquid-crystal polymers. If this polymer mixture is rapidly heated in a mold, the sulfoxide bridges are reduced to sulfide, gas evolution occurring. This gas evolution leads to foaming of the thermoplastics used.
In the examples, Tg is the glass transition temperature, Tm is the melting point.
Examples 1. In a reaction vessel, 3 g of a poly(phenylene sulfide) (PPS) powder (Mw 30,000) having a mean particle diameter of 500 x 10~6m were reacted in 5 ml of N2O4 at a temperature of minus 40~C for 2 hours.
After the reaction, the polymer powder was separated off from the N2O4 and dried. In the infrared spectrum and also in the ESCA spectrum, only the exclusive formation of sulfoxide groups could be observed.
Tg: 240~C, Tm: 2 370~C (decomposition).
The sulfur/oxygen ratio of the polymer obtained was 1:1 in the ESCA analysis, ie. the S bridges of the PPS used . ~ CA 02204904 1997-0~-08 r were oxidized to SO groups.
2. In a reac~ion vessel, 3 g of a poly~phenylene sulfide) (PPS) powder (Mw 30,000) having a mean particle diameter of 500 x 10~6m were reacted in 5 ml of N2O4 at a temperature of 50~C for 1 hour.
After the reaction, the polymer powder was separated off from the N204 and dried. In the infrared spectrum and also in the ESCA spectrum, likewise, only the exclusive ~ormation of sulfoxide groups could be observed.
Tg: 240~C, Tm: ' 370~C (decomposition).
The sulfur/oxygen ratio of the polymer obtained was 1:1 in the ESCA analysis.
The object of the invention is to develop processes for the oxidation of sulfur-cont~;n;ng polymers such as poly(arylene sulfides) which require substantially shorter reaction times at mild reaction temperatures. The use of poly(arylene sulfides) having relatively high molecular weights as starting material is also desirable.
The object was achieved by the use of NO2/N204 as oxidizing agent, the proportion of N2O4 being determined by the reaction temperature (see above).
The e~uilibrium system NO2/N2O4 used for the oxidation is termed N204 below.
The invention relates to a process for the oxidation of a sulfur-cont~;n;ng polymer in which the sulfur-con-2 0 t~; n; ng polymer is brought into contact with NO2 or N2O4.
The oxidation of the sulfur-cont~;n;ng polymer N2O4 according to the invention leads with high selec-tivity to the formation of sulfoxide bridges. This is all the more surprising since N2O4 is an extremely strong oxidizing agent. By appropriate use of the amount of N2O4 and the choice of reaction duration it is possible either to convert the sulfur bond completely into the sulfoxide bond or to achieve any desired partial oxidation of the sulfur bonds in the sulfur-cont~;n;ng polymer. A hetero-geneous oxidation or partial oxidation of the sulfur-cont~;n;ng polymer can proceed fully in and right through a material or only at the surface of a material. A
heterogenous oxidation right through is achieved all the more easily, the finer is the material. Particularly , CA 02204904 1997-0~-08 suitable materials for oxidation right through are ultrathin or ultrafine particles, fibers, films, moldings or coatings. In this case a highly uniform oxidation is achieved. Ultrathin or ultrafine denotes a diameter or a thickness of up to 50 ~m, preferably 1 to 30 ~m, in particular 5 to 25 ~m. The invention therefore further relates to particles, fibers, films, moldings or coatings o~ poly(arylene sulfoxide) ha~ing a diameter or a thick-ness of up to 50 ~m.
The ultrathin or ultrafine poly(arylene sulfoxide) parts can be produced by oxidation of appropriately ~;m~ncioned poly(arylene sulfide) parts and feature a very high homogeneity of composition or a very uniform degree of oxidation, by which means, for example, the mechanical, physical and chemical properties are improved. Ultrathin or ultrafine poly(arylene sulfoxide) parts show, for example, because of their homogeneity, improved heat stability and chemical resistance.
For example, woven fabrics or no~woveLls made of ultrathin poly(arylene sulfoxide) fibers are suitable for pro~ ;ng filters for high-temperature applications.
Ultrafine particles of poly(arylene sulfoxide) are particularly suitable for producing foamed poly(arylene ~ulfide). Poly(arylene sulfoxide) as a blowing agent for poly(arylene sulfide) is described in German Patent Application P 44 28 737.2 of 15th August 1994 with the title "Poly(arylene sulfide) foams and process for their production", which is incorporated herein by reference.
The expression sulfur-contA;n;ng polymers includes polymer~ which contain at least one arylene thioether unit (-AR-S-; Ar: arylene) or an aliphatic thioether unit (-Alk-S-; Alk: alkylene), eg. poly(arylene thioethers) or polysulfides. The arylene groups can comprise m~nsnnclear or polynuclear aromatics. The arylene groups comprise at least one 5- or 6-membered ring which can contain one or . CA 02204904 1997-0~-08 more heteroatoms and can be unsubstituted or substituted.
Heteroatoms are, eg., nitrogen or oxygen, substituents are, eg. linear or branched alkyl groups. The sulfur-containing polymers can also contain, apart from sulfur bridges (-S-), sulfoxide groups (-SO-) or sulfone groups (-SO2-). Arylenes are, for example, phenylene, biphenyl-ene (-C6X4-C6H4-) or naphthylene which can be monosubsti-tuted ~r polysubstituted. Substituents are, for example, straight-chain, cyclic or branched C1-C20-hydrocarbon radicals, such as C1-C10-alkyl radicals, eg. methyl, ethyl, n-propyl, isopropyl, n-butyl, t-butyl or n-hexyl, or C6-C14-aryl radicals, eg. phenyl or naphthyl; halide, sulfonic acid, amino, nitro, cyano, hydroxyl or carboxyl groups.
Preferred sulfur-containing polymers are poly(arylene thioethers), also termed poly(arylene sulfide), in particular poly(phenylene sulfide).
In the oxidation of poly(arylene sulfide) by N2O4, poly(arylene sulfoxides) are formed. Poly(arylene sul-foxides) are polymers which contain at least one arylenesulfoxide unit (-Ar-SO-; Ar = arylene radical, SO = sulfoxide group).
Poly(arylene sulfides), in particular poly(phenylene sulfide), may be prepared on the basis of the reaction of dihalogenated aromatics with sodium sulfide according to ~n~o~ns and HILL. Poly(phenylene sulfide) and its prepa-ration are described in ''u~ nn~s Encyclopedia of Industrial Chemistry, Volume A21, B. Elvers, S. Hawkins and G. Schulz (Eds.), VCH, Weinheim-New York 1992, pp.
463-472), which is incorporated herein by reference. The synthesis of sulfone-cont~;n;ng poly(arylene sulfides) is described in Chimia 28 (1974) 567, which is incorporated herein by reference.
A suitable sulfur-cont~;n;ng polymer is, for example, one ha~ing a mean molecular weight Mw of 4000 to 400,00Q, . CA 02204904 1997-0~-08 - preferably 10,000 to 150,000, in particular 25,000 to 100,000, determined by GPC.
The mean particle size D50 of the polymers used is generally in the range of about 5 x 10-7 to about 5 x 10-2 m, preferably about 10-5 to about 10-3 m, and in particular about 10-5 to about 2 x 10~4m.
The sulfur-cont~in;ng polymer is generally present in solid form at the beg;nn;ng of the oxidation reaction. It can also be used in dissolved form or in suspension.
When dissolved sulfur-cont~;n;ng polymer is used, the reaction with N2O4 is a homogeneous oxidation reaction.
When solid or suspended sulfur-cont~;n;ng polymer is used, the reaction with N204 is a heterogeneous oxidation reaction.
The suspension medium for the sulfur-cont~;n;ng polymer is generally a chemically inert sol~ent. Thus, liquids can be used in which the reaction product is insoluble, for example acetic acid, l,1-dichloroethane, dichloro-methane or 1,1,2-trichloro-1,2,2-trifluoroethane. Xow-ever, it is also possible to use liquids in which theoxidation product dissolves, such as dichloroacetic acid, trichloroacetic acid or trifluoroacetic acid.
The reaction temperatures are generally in the range from minus 40 to + 100~C, preferably from minus 5 to 80~C. The reaction time required depends on the supply of N2O4 and the type of reactor chosen and is generally 1 minute to 5 hours, preferably 15 minutes to 120 minutes, and in particular 15 minutes to 60 minutes. When the reaction conditions are optimized, it is possible to achieve reaction times below one minute.
The oxidation according to the invention is carried out, for example, in an atmosphere comprising N2O4 having a concentration greater than 40 mol %, preferably greater CA 02204904 1997-0~-08 than 60 mol %, and in particular greater than 70 mol %.
The reaction can be carried out in a reactor whose temperature can be controlled, statically or with stir-ring, at atmospheric pressure or under pressure.
Oxidation by N204 can be performed by liquid N204.
In the oxidation of a sulfide group to sulfoxide, N204 is reduced to N203. By a subsequent reaction with atmos-pheric oxygen, this N203 can be reoxidized back to N204 and thus reco~ered, so that the process described here can be carried out highly cost-effectively.
The reoxidation of N203 to N204 can also take place, for example, in a loop reactor in which the N204 is circu-lated; in the reaction loop it oxidizes the sulfur-containing polymer and in the return loop is brought into contact with oxygen and reoxidized to N204.
It is also possible to carry out the reaction with substoichiometric amounts of N204 if oxygen or air is blown through the reaction solution. In this case, the N203 formed in the reaction is immediately reoxidized to N204 in the reaction mixture and can thus oxidize a plurality of sulfide groups to sulfoxide. The N204 used under such reaction conditions acts as an oxygen transfer agent (catalyst). Consequently, the degree of oxidation of the polymer can be set specifically by the reaction duration.
After oxidation is completed, the N204 can be expelled from a reactor, eg. from a solution or suspension, by a vigorous air stream or oxygen stream and condensed out in a cooling apparatus and thus recovered.
In addition, it is possible to carry out the reaction with a substoichiometric amount of N204 in an autoclave with an oxygen overpressure. The N203 formed in the oxidation is here immediately reoxidized to N204.
. CA 02204904 1997-0~-08 When a sol~ent or suspension medium is used, the reaction can be carried out either discontinuously in a stirred tank (batch process) or in a continuous reactor, for example a reactor cascade, comprising a plurality of pots, or a flow tube. When a reactor cascade is used, the reaction products can, for example, be combined with the solvent or dispersion medium in the first cascade pot, the reaction and oxygen addition can take place in the second cascade pot and the N204 can be expelled when oxidation is completed in a third cascade pot.
The N204 (after the reoxidation with oxygen) and, if appropriate, the solvent or suspension medium, can be used for further reactions either in a discontinuous or in a continuous reaction course, so that in the oxidation reaction all components can be used again and no residues cont~m;n~ting the environment occur.
The degree of oxidation of the polymer which can be achieved depends on the precise reaction conditions.
When air or oxygen is added during the reaction, because of the immediate reoxidation of the N203 formed to N204, higher degrees of oxidation can be achieved than corres-pond to the stoichiometry of the N204 used.
The oxidation products of the reaction of N204 with a sulfur-contA;n;ng polymer are in many cases soluble in dichloroacetic acid and can be processed therefrom in conventional proce~ses.
The oxidized or partially oxidized sulfur-contA;n;ng polymers obtained according to the invention may either be processed thermoplastically or may be further pro-cessed, for example, by customary sintering processes,but this is dependent on their melting points. The first group, i.e. the compounds which can be processed thermo-plastically, can be converted into moldings and func-tional components by processing methods customary for . , CA 02204904 1997-0~-08 ~.
thermoplastics, eg. injection molding or extrusion. The molding compounds can also contain known pulverulent fillers such as chalk, talc, clay, mica and/or fibrous reinforcing agentsr such as glass fibers and carbon fibers, whiskers, and other conventional additives and processing aids, eg. lubricants, release agents, antioxi-dants and W stabilizers. Such components are used a~
heavy-duty functional components, for example in aircraft and automobile construction and in chemical plant con-struction.
The second group, ie. the polymers which can be processedby sintering processes, are used in functional components having high temperature and chemical stress.
The compounds obtained according to the invention can, moreover, also be added in powder mixtures to other high-temperature thermoplastics, eg. PPS or liquid-crystal polymers. If this polymer mixture is rapidly heated in a mold, the sulfoxide bridges are reduced to sulfide, gas evolution occurring. This gas evolution leads to foaming of the thermoplastics used.
In the examples, Tg is the glass transition temperature, Tm is the melting point.
Examples 1. In a reaction vessel, 3 g of a poly(phenylene sulfide) (PPS) powder (Mw 30,000) having a mean particle diameter of 500 x 10~6m were reacted in 5 ml of N2O4 at a temperature of minus 40~C for 2 hours.
After the reaction, the polymer powder was separated off from the N2O4 and dried. In the infrared spectrum and also in the ESCA spectrum, only the exclusive formation of sulfoxide groups could be observed.
Tg: 240~C, Tm: 2 370~C (decomposition).
The sulfur/oxygen ratio of the polymer obtained was 1:1 in the ESCA analysis, ie. the S bridges of the PPS used . ~ CA 02204904 1997-0~-08 r were oxidized to SO groups.
2. In a reac~ion vessel, 3 g of a poly~phenylene sulfide) (PPS) powder (Mw 30,000) having a mean particle diameter of 500 x 10~6m were reacted in 5 ml of N2O4 at a temperature of 50~C for 1 hour.
After the reaction, the polymer powder was separated off from the N204 and dried. In the infrared spectrum and also in the ESCA spectrum, likewise, only the exclusive ~ormation of sulfoxide groups could be observed.
Tg: 240~C, Tm: ' 370~C (decomposition).
The sulfur/oxygen ratio of the polymer obtained was 1:1 in the ESCA analysis.
3. Poly(phenylene sulfoxide) (PPSO) In a reaction vessel, 108 g of a poly(phenylene sulfide) (PPS) powder (Mw 30,000) having a mean particle diameter of 20 x 10~6m were dispersed in 500 ml of dichloroacetic acid at a temperature of 10~C. With good stirring, 40 ml of N2O4 were added dropwise in the course of 40 minutes.
The temperature of the reaction mixture was increased to 40~C and an air current of 50 l/min was blown through for 80 minutes. A homogenous brownish solution resulted. The N2O4 was then expelled with a more vigorous air current (100 l/min), the solution was precipitated in water, and the product was filtered off by suction, washed with water and dried. In the infrared spectrum and also in the ESCA spectrum, only the exclusive formation of sulfoxide groups could be observed.
Tg: 240~C, Tm: ' 370~C (decomposition).
The sulfur/oxygen ratio of the polymer obtained was 1:1 in the ESCA analysis.
The temperature of the reaction mixture was increased to 40~C and an air current of 50 l/min was blown through for 80 minutes. A homogenous brownish solution resulted. The N2O4 was then expelled with a more vigorous air current (100 l/min), the solution was precipitated in water, and the product was filtered off by suction, washed with water and dried. In the infrared spectrum and also in the ESCA spectrum, only the exclusive formation of sulfoxide groups could be observed.
Tg: 240~C, Tm: ' 370~C (decomposition).
The sulfur/oxygen ratio of the polymer obtained was 1:1 in the ESCA analysis.
4. Poly(phenylene sulfoxide) (PPSO) A dispersion of poly(phenylene sulfide) (PPS) powder (Mw 30,000) having a mean particle diameter of 20 x 10~6m in acetic acid and N2O4 dissolved in acetic acid was ~ ~ CA 02204904 1997-0~-08 "
continuously added to a reactor cascade comprising three reaction vessels. The temperature of the first cascade pot was 40~C and that of the second and third pots was 50~C. In the second pot, an air current of 50 l/min was additionally passed through, and in the third cascade pot an air stream of 100 l/min was passed through. The mean residence time of the overall cascade was approximately 90 minutes. After passage through the cascade, the polymer powder was filtered off by suction, washed with water, separated off and dried. In the infrared spectrum and also in the ESCA spectrum, the formation of sulfoxide groups could be observed.
Tg: 240~C, Tm: ~ 370~C (decomposition).
The sulfur/oxygen ratio of the polymer obtained was 1:0.75 in the ESCA analysis.
continuously added to a reactor cascade comprising three reaction vessels. The temperature of the first cascade pot was 40~C and that of the second and third pots was 50~C. In the second pot, an air current of 50 l/min was additionally passed through, and in the third cascade pot an air stream of 100 l/min was passed through. The mean residence time of the overall cascade was approximately 90 minutes. After passage through the cascade, the polymer powder was filtered off by suction, washed with water, separated off and dried. In the infrared spectrum and also in the ESCA spectrum, the formation of sulfoxide groups could be observed.
Tg: 240~C, Tm: ~ 370~C (decomposition).
The sulfur/oxygen ratio of the polymer obtained was 1:0.75 in the ESCA analysis.
5. Production of ultrathin poly(arylene sulfoxide) fibers The production of ultrathin poly(phenylene sulfide) fibers is described, for example, in EP 283 520 Bl (Example 4, page 8), which is incorporated herein by reference.
Ultrathin poly(arylene sulfide) or poly(phenylene sulfide) fibers are treated with N2O4 similarly to Examples 1, 2 or 4.
Ultrathin poly(arylene sulfoxide) or poly(phenylene sulfoxide) fibers are obtained.
Examples 1 and 2 show that different reaction tempera-tures give the same results.
Ultrathin poly(arylene sulfide) or poly(phenylene sulfide) fibers are treated with N2O4 similarly to Examples 1, 2 or 4.
Ultrathin poly(arylene sulfoxide) or poly(phenylene sulfoxide) fibers are obtained.
Examples 1 and 2 show that different reaction tempera-tures give the same results.
Claims (10)
1. A process for the oxidation of a sulfur-containing polymer, which comprises bringing the sulfur-con-taining polymer into contact with an NO2/N2O4 equi-librium system, with the oxidation occurring in an N2O4 atmosphere having a concentration of greater than 40 mol% or being carried out using liquid N2O4.
2. The process as claimed in claim 1, wherein the sulfur-containing polymer is present in solid form, dissolved or suspended.
3. The process as claimed in claim 1 or 2, wherein the sulfur-containing polymer is a poly(arylene sulfide), in particular poly(phenylene sulfide).
4. The process as claimed in one or more of claims 1 to 3, wherein the mean particle size D50 of the sulfur-containing polymers is in the range from about 5 x 10-7 to about 5 x 10-2 m, preferably about 5 x 10-5 to about 10-3 m, and in particular about 10-5 to about 10-4 m.
5. The process as claimed in one or more of claims 1 to 4, wherein the oxidation is carried out in an atmosphere having a concentration of preferably greater than 60 mol% and in particular greater than 70 mol%.
6. The process as claimed in one or more of claims 1 to 5, wherein NO2 or N2O4 is used as catalyst in the presence of oxygen.
7. The process as claimed in one or more of Claims 1 to 6, wherein the sulfur-containing polymer is suspended in acetic acid, 1,1-dichloroethane, chloro-methane, 1,1,2-trichloro-1,1,2-trifluoroethane, dichloroacetic acid, trichloroacetic acid or tri-fluoroacetic acid.
8. The process as claimed in one or more of Claims 1 to 7, wherein the sulfur-containing polymer is used as powder, fiber, nonwoven, woven fabric, film or molding.
9. A particle, fiber, film or molding of poly(arylene sulfoxide) having a diameter or a thickness of up to 50 µm.
10. Use of the oxidized sulfur-containing polymer obtained as claimed in one or more of claims 1 to 8 for the production of moldings and functional components.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP4440010.1 | 1994-11-09 | ||
| DE19944440010 DE4440010A1 (en) | 1994-11-09 | 1994-11-09 | Oxidn. of sulphur-contg. polymers, esp. polyarylene sulphide |
| DE19531163.9 | 1995-08-24 | ||
| DE19531163A DE19531163A1 (en) | 1995-08-24 | 1995-08-24 | Oxidn. of sulphur-contg. polymer and ultra-fine poly:arylene sulphoxide |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2204904A1 true CA2204904A1 (en) | 1996-05-23 |
Family
ID=25941838
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002204904A Abandoned CA2204904A1 (en) | 1994-11-09 | 1995-11-06 | Oxidation of sulfur-containing polymers by no2/n2o4 |
Country Status (8)
| Country | Link |
|---|---|
| EP (1) | EP0791027B1 (en) |
| JP (1) | JPH10508646A (en) |
| KR (1) | KR970707212A (en) |
| AT (1) | ATE184036T1 (en) |
| CA (1) | CA2204904A1 (en) |
| DE (1) | DE59506741D1 (en) |
| TW (1) | TW337528B (en) |
| WO (1) | WO1996015178A1 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0829505A1 (en) * | 1996-09-17 | 1998-03-18 | Ticona GmbH | Soluble polyarylenesulphoxides, process for the manufacture and use thereof |
| DE19916495A1 (en) | 1999-04-12 | 2000-10-19 | Ticona Gmbh | Process for the oxidation of polyarylene sulfide to polyarylene sulfoxide using nitric acid |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4251575A (en) * | 1974-10-31 | 1981-02-17 | Phillips Petroleum Company | Chemical treatment of poly(arylene sulfide)-containing articles |
| US3948865A (en) * | 1974-10-31 | 1976-04-06 | Phillips Petroleum Company | Chemical treatment of arylene sulfide polymers |
| JP2820976B2 (en) * | 1989-09-19 | 1998-11-05 | 株式会社クラレ | Composite fiber excellent in dimensional stability and method for producing the same |
| JPH03104923A (en) * | 1989-09-19 | 1991-05-01 | Kuraray Co Ltd | Polyphenylene sulfide fiber excellent in dimensional stability and production thereof |
| WO1991018041A1 (en) * | 1990-05-16 | 1991-11-28 | Solvay & Cie | Functional polymers derived from arylene polysulphides, and production method therefor |
| US5209855A (en) * | 1991-12-10 | 1993-05-11 | Phillips Petroleum Company | Continuous acid washing of polymer resin with controlled metering of acid |
| DE4314736A1 (en) * | 1993-05-04 | 1994-11-10 | Hoechst Ag | Oxidation of polyarylene sulfides |
-
1995
- 1995-11-06 EP EP95937866A patent/EP0791027B1/en not_active Expired - Lifetime
- 1995-11-06 DE DE59506741T patent/DE59506741D1/en not_active Expired - Fee Related
- 1995-11-06 WO PCT/EP1995/004339 patent/WO1996015178A1/en not_active Application Discontinuation
- 1995-11-06 KR KR1019970703097A patent/KR970707212A/en not_active Application Discontinuation
- 1995-11-06 CA CA002204904A patent/CA2204904A1/en not_active Abandoned
- 1995-11-06 JP JP8515696A patent/JPH10508646A/en active Pending
- 1995-11-06 AT AT95937866T patent/ATE184036T1/en not_active IP Right Cessation
- 1995-11-27 TW TW084112631A patent/TW337528B/en active
Also Published As
| Publication number | Publication date |
|---|---|
| ATE184036T1 (en) | 1999-09-15 |
| TW337528B (en) | 1998-08-01 |
| EP0791027A1 (en) | 1997-08-27 |
| DE59506741D1 (en) | 1999-10-07 |
| WO1996015178A1 (en) | 1996-05-23 |
| KR970707212A (en) | 1997-12-01 |
| EP0791027B1 (en) | 1999-09-01 |
| JPH10508646A (en) | 1998-08-25 |
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