DE2009065B2 - PROCESS FOR MANUFACTURING STABILIZED POLYPHENYLENE OXIDES - Google Patents

Description

Il

(1)

in the R ₁ . R ₂ . R, and R _s a hydrogen, chlorine, bromine or iodine atom, a methyl, ethyl. Propyl, allyl, phenyl. Benzyl. Methylbenzyl-, chloromelhyl-, bromomethyl-. Cyanoethyl, cyano. Methoxy-, alhoxy-, chlorometho.xy-, phenoxy-. Nitro or amino group, R _{4 is} hydrogen, chlorine. Bromine or iodine atom and η denotes the degree of polymerization, with a boron trihalide or a complex of this boron compound with water. Amines, amides. Nitriles. Ethers, hydroxyl groups. Carboxylic acids. Sulfonic acids. Esters. Treated ketones, nitro compounds or phosphines at temperatures below 100 C for a period of 2 to 120 minutes.

2. The method according to claim 1, characterized in that the treatment in the presence 1 to 200 times the amount by weight, based on polyphenylene oxide. an inert reaction medium performs.

3. The method according to claim I and 2. characterized .'5 that one has a boron trifluoride complex with methanol. Ethanol. Acetic acid, ethyl formal. Phenol. Diethyl ether Ethylamine or acetonitrile used.

4. The method according to claim I to 3, characterized in that gaseous boron trifluoride used.

substituted hydrocarbon or alkoxy radical, so these substituents are subject to partial oxidation during the polymerization and are formed Aldehyde or hydroxyl groups, which are the reason for the deterioration in the polymer properties are due to thermal oxidation. Stand under certain polymerisation conditions also hydroperoxides in the polymers, which also impair the thermal stability. Besides, one accepts. that the polymers contain small amounts of impurities are difficult to remove in conventional cleaning applications and which also reduce the quality of the polymer as a result of thermal!. · "cause oxidation. In addition, there are some causes of thermal instability not yet clarified.

The object of the invention was therefore to overcome the aforementioned disadvantages and a method for to develop effective stabilization of polyphenylene oxides.

Thus, the invention relates to a process for the preparation of stabilized polyphenylene oxides, which thereby is marked. that a polyphenylene oxide of the general formula I

45

Polyphenylene oxides have hitherto been of great interest as excellent polymers in terms of both their thermal and chemical resistance as well as their mechanical and electrical resistance Properties found. However, the polyphenylene oxides are oxidationscmpi'mdlicli at elevated temperatures. They are thermally oxidized relatively quickly, especially at high temperatures in the presence of air or oxygen. a decrease in strength and a deterioration in flow properties occur.

It has been found that by thermal oxidation caused an adverse effect on the polymer properties is mainly due to dcpolymerization. The depolymerization is formed by the terminal free hydroxyl groups or by electron transfer as a result of cleavage caused by hydrogen atoms from the terminal hydroxyl groups. 3 sit polyphenylene oxides in at least one de · 2-, 3-. 5 or 6 positions the Phenylenbaustcine z. L. such oxidizable substituents as a hydrocarbon radical or a R,

..— O-

R,

-H

in the R ₁ . R ₂ . R ₃ and R _{5 are} hydrogen, chlorine. Bromine or iodine, a methyl, ethyl, propyl. Allyl-. Phenyl, benzyl. Methylbenzyk Chloromelhyl-. Bromomethyl-. Cyanoethyl. Cyano, methoxy, ethoxy. Chloromethoxy-. Phenoxy-. Nitro or amino group c. R ₄ denotes a hydrogen, chlorine, bromine or iodine atom and η denotes the degree of polymerization with a boron trihalide or a complex of this boron compound with water. Amines. Amides. Nitriles. Ether. Hydroxyl groups. Carboxylic acids. Sulfonic acids. Esters. Ketones. Nitro compounds or phosphines treated at temperatures below 100 C for a period of 2 to 120 minutes.

The polyphenylene oxides produced in this way show no discoloration even at high temperatures, no decreased strength or poor fluidity.

The process of the invention gives thermostable polyphenylene oxides in high yield.

It has not yet been clarified by which reaction the stabilization of polyphenylene oxides takes place with relatively small amounts of the boron compound. That However, the method of the invention is surprisingly effective. The fact that opposite thermal Oxidation-sensitive polyphenylene oxides can be stabilized effectively and within a short time, was previously not considered possible and is of great economic importance.

Specific examples of the boron compounds are boron trifluoride. Boron trichloride. Boron tribromide. Boron triiodide. Trimethyl boron, triethyl boron. Tri-n-butyl boron, diflutromethyl boron. Chlorodimethylboron, Difluorovinylboron, Chlor-1-Boraindan. Boron trifluoride complexes with aniline. Piperidine, pyridine. Ethylamine, triethylamine,

N-Meihvl-N-phenylaeeiamid. Acetonitrile. DiälhvlinlKT. Bulsläthcr, Telrahyclrofunin. Methanol. Ethanol. I ¹ IiC [UiI. p-cresol. 2.6-Di-tcrt.-hat> 1 -p-krusnl. I sMüs.iurc. Ethyl firm. Methylacelal. Acetone or Tnmcthv! Phosphine. Borlrichloridkomplexe with Aiii s Im or pyridine, a complex from Diehlorälhylbor with

I iimeiliylaniin. Boron trihromide complexes with aniline ,, o.i Pv ridin. or trimelhylboron complexes with Ammoiii.ii .. Triamylphosphine or Athykimin.

! "jιc used in the method of the invention '.h-ngean boron compound is not particularly limited: μ mialervvcise are 0.01 to 10 percent by weight. ■ .. Approximately 0.1 to 5 percent by weight, based on

ι, s (weight of polyphenylene oxide. use "!.

specific examples of polyphenylene oxides of the general Formula (I) are:

Poly-2.o-dimethyl-1,4-phenyleno \ id.

Poly-i-diethyl-l ^ -phenylene oxide.

Poly-2,6-dipropyl-1,4-phenylene oxide.

Poly-I-methyl-o-isopropyl-1,4-phenylene oxide.

Poly ^ .fi-dimethoxy-l ^ -phenvlenoxid.

Poly ^ .o-dichloromethoxy-l ^ -phonylene oxide.

Poly-dichloromethyl-1,4-phenylene oxide.

Poly ^ .a-dibromomethyl-1- ^ -phenylcnoxid.

Poly-2,6-diphenyl-l. 4-phenylene oxide.

Poly ^ .o-ditolyl-M-phenylcnoxide.

Poly-2.6-dichloro! -1.4-phenylene oxide or

Poly-2.5-dimethyl-1.4-pbenylene oxide.

30th

In general, the handling of the polyphenylene oxide is used preferably carried out with the boron compound in the presence of a reaction medium. in order to be able to better control the process conditions according to the invention. The procedure will /. B. carried out so that the boron compound is directly a solution of the polyphenylene oxide in one reaction medium or a polymerization reaction mixture added from the polymer and a reaction medium. The procedure can be carried out according to the Polymerization or stabilization conditions can be selected arbitrarily. The reaction medium is any medium inert to polyphenylene oxide and the boron compound is suitable, provided that it is in the Ikhandlungstenipcralur is liquid. Even if that Process in the presence of a small amount of a medium reactive with the boron compound is carried out, this does not have any further adverse effect. The boron compound is through Reaction with the reactive reaction medium partly consumed.

Examples of such reaction media are aliphaticc. cycloaliphatic or aromatic hydrocarbons or their derivatives, such as nitriles. Halides. Hydroxides. Ether. Ketones. Lactones or sulfonates. Generally heptane. Benzene, Toluene. Xylene. Monochlorobenzene. Dichlorobenzene, nitrobenzene. , -'-methoxyethyl alcohol. Methylcyclohexane, Dichloromethane, dichloroethane. Chloroform, cresol. Diethyl ether Tetrahydrofuran. Dioxane. Cyclohexa »fco non. Acetonitrile or mixtures thereof are used.

The reaction medium is used in 1 to 2 (X) times the weight, preferably in 2 to 100 times the weight, based on the polyphenylene oxide. ^fi 5

If the process is carried out in the absence of a reaction medium, this is generally done * / .. B. so. that the polyphenylene oxide is in powder form with the boron compound, either in gaseous form or liquid form.

The process can be carried out either under normal pressure or under increased or reduced pressure carried out to the boron compound and / or the reaction medium in the desired Aguregatzusland bring to.

The temperature can be within the temperature range, in which no decomposition of the polyphenylene oxide occurs, can be freely selected and omitted 100 C.

The duration of treatment depends on the type of boron compound and the treatment temperature. It is 2 to 120 minutes, preferably 5 to 60 minutes.

If the process of the invention is carried out in the presence of a reaction medium, the liquid obtained after the treatment of the polyphenylene oxide with the boron compound is finished poured into a sufficient amount of a solvent poor in terms of polyphenylene oxide, a polymer separating out. The polymer is then filtered off and one receives the desired product after washing and drying. Bad solvents for polyphenylene oxide are z. B. aliphatic hydrocarbons such as heptane. Hexane. Potroethcr or Ligroin. Alcohols, like methanol. Ethanol. Propanol. Butanol or cyclohexanol. Ketones, such as acetone or meth / ethyl ketone. Ethers, such as diethyl ether or benzyl ether. Acids such as sulfuric acid or acetic acid. Acid anhydrides. such as acetic anhydride, or acid amide c. like dimethylformamide.

In some cases, the stabilized polymer can also be obtained by following the Treatment of the polyphenylene oxide with the boron compound or its complex obtained liquid evaporated to dryness or spray dried.

If a polyphenylene oxide stabilized by the process of the invention and an unstabilized polyphenylene oxide are each pressed for 10 minutes at 270 ° C. with a pressure of 100 kg cm ² to form a film and their colorations are compared, it can be seen that the unstabilized polymer has been thermally oxidized and has turned brown. while the film made from the stabilized polymer is hardly colored.

Example I.

H) Og yellowish white poly-2,6-dimethyl-1,4-phenylene oxide with a maximum viscosity number of 0.72 dl g (measured in chloroform at 25 C) are in 900 ml Xylene dissolved. After adding 10 g of a boron trifluoride-diethyl ether complex the mixture is stirred at 70 ° C. for 1 hour. Then the mixture is poured into 250OmI methanol. The separating Precipitation is filtered off. washed with methanol and water and then 10 hours at 90 C dried. 96.1 g (96.1%) of stabilized material are obtained and discolored, white polymer with a Maximum viscosity number of 0.64 dl g.

As a measure of the thermal resistance to oxidation of the stabilized polyphenylene oxide, the discoloration and the cross-linking ratio are dependent determined by the duration of the heating.

The stabilized and the unstabilized polyphenylene oxide are each pressed for 10 minutes at 270 "C under a pressure of 100 kg" cm ² to form films 1 mm thick

Foil found Trum that this did not stabilize Has discolored polymer according to Hiaiin. while that stabilized polymer is hardly colored.

In addition, the stabilized and the unstabilized polyphenylcivixide are each 1.5 percent by weight, based on polymer. 2.6-Di-lert.-but \ l-p-cresol is incorporated as a stabilizer. The mixtures are processed in each case 7 minutes at 2S0 C on a whale kneader and then 10 minutes at 270 C under a pressure of 100 kg cnr to foils 1 mm thick pressed. Lin color comparison of Films shows that the unstabilized polymerizate a discoloration occurred after Tiefhraun is. while the stabilized polymer has hardly discolored.

Furthermore, 0.05 mm thick films, each made of chloroform solutions of the stabilized and des unstabilized polymer have been prepared, in an oxygen atmosphere for 30 minutes at 210.degree held. The films are then each extracted for 10 hours with chloroform in a Soxhlet apparatus. The ratio of the film weights after and before the extraction. expressed in percent, is expressed as the reduction ratio of the respective polymer viewed. In this test, the result is not stabilized Polymer has a crosslinking ratio of 91.4%. while the crosslinking ratio of the stabilized Polymer is 49.7%.

Example 2

20.0 g of the poly-2,6-dimethyl-1,4-phenylene oxide used in Example I. are dissolved in 80 ml of xylene. After adding 0.2 g of a boron trifluoride-diethyl ether complex the mixture is stirred at 50 ° C. for 5 minutes. When working up according to the example I get 19.2 g (95.9 ", I of a stabilized, decolorized polymer.

Hei the test of the thermal oxidation resistance According to Example I, the film made from the ϊ unstabilized polymer is colored brown, while the film made from the stabilized polymer shows no discoloration. The networking ratio of the stabilized polymer is · 50.2 "■■ ,.

Example 3

10.0 g of poly-2,6-dipiethyl-1,4-phenylene oxide with a limiting viscosity number of 0.68 dl / g (measured in chloroform at 25 ° C.) are dissolved in 90 g of xylene. After adding 0.6 g of a boron trifluoride-phenol complex, the mixture is kept at 60 ° C. for 20 minutes. Working up as in Example 1 gives 9.59 g of a stabilized, er.'-colored Ρ ° ^{| ν} merizate with an intrinsic viscosity of 0.60 dl / g. When testing the thermal oxidation resistance according to Example I, the unstabilized polymer shows a brown discoloration, while the stabilized polymer is not discolored.

Example 4

Example 3 is repeated, but instead of the boron trifluoride-phenol complex, the in Boron compounds listed in Table I are used. The reaction conditions and the yields are also given in Table I. Work-up is carried out according to Example 1 in each case.

When testing the thermal resistance to oxidation According to Example 1, it can be seen that the films made from the unstabilized polymers in each case are discolored brown, while the films made from the stabilized polymers are hardly colored in each case are.

Tabel

Search

No

I.
τ

3
4th
5
6th
7th
8th
9
10

Horverhiruluiii:

Boron trifluoride-methanol-complcx
Boron trifluoride ethanol complex
Boron rifluoride-acetic acid complex
Boron rifluoride ethyl formate complex Boron rifluoride phenol complex
Boron rifluoride-phenol complex
Boron trifluoride dieth ν lather complex Boron rifluoride diethvlether complex Boron trifluoride acctonitrile complex
Boron rifluoride. gaseous

Menno
«Si Tompcnilur
I Cl Line
iMin.i Aushciili.
K icuichls
pro / cnll 1.0 70 30th 96.3 0.5 60 10 97.7 1.0 50 30th 96.8 0.5 60 30th 97.5 1.0 60 30th 94.1 0.3 50 5 97.2 0.1 70 60 97.1 0.2 30th IO 98.8 0.5 60 30th 97.9 not determined 60 30th 97.5

Example 5

Example 3 is carried out using 0.8 g of a boron trifluoride-ethylamine complex in place of the boron trifluoride-PhcnoI complex and a reaction time of 30 minutes instead of 20 minutes. This gives 9.71 g of a stabilized polymer.

When testing the thermal resistance to oxidation according to Example 1, the stabilized material changes color Polymer less than the unstabilized

PnlvmrrUiit Example 6

Example 3 is made using 0.8 g of boron tribromide instead of the trifluoride-phenol complex repeated. The reaction time is 1 hour at 70 ° C. When working up according to Example 1, this is obtained one 9.59 g of a stabilized polymer.

When checking the thermal oxidation properties According to Example I, it can be seen that the films made from the stabilized polymer are less discolored are than the films made from the unstabilized polymer.

Example 7

Hinc reaction liquid. clic 19.8 g poly-2.6-dimcthy! - !, 4-phenylene oxide with a maximum viscosity of 0.77 dl / g, produced by oxidation polymerization of 2,6-xylenol in a mixture of xylene and a small amount of methanol in the presence a manganese chloride sodium methylate catalyst, is distilled at 50 C / KX) Torr freed from methanol and water. After adding 1.0 g of a boron trifluoride-diethyl ether complex to the residue, the mixture is kept at 60 ° C. for 10 minutes. The mixture obtained is poured into a large amount of methanol containing a small amount of hydrochloric acid. The separating Precipitate is filtered off, washed and then dried at 90 ° C. for 10 hours. You get 18.8g of a stabilized polymer with an intrinsic viscosity of 0.75 dl / g.

The test of the thermal resistance to oxidation according to Example I shows that this stabilized The polymer is much less discolored than the unstabilized polymer.

Example 8

10.0 g of each of the polyphenylene oxides listed in Table II are dissolved in 100 ml of xylene. To Addition of 0.5 g of a boron trifluoride-diethyl ether complex the solutions are stirred for 30 minutes at 60 ° C. Working up is carried out according to the example I.

When the thermal oxidation resistance is tested according to Example I, it is found that the films from the unstabilized polymers are each colored brown, while the films from the stabilized Polymers are hardly colored in each case.

Table II St. yield Ver (Cicweight Polvphcnvlcnoxiil (dl g) * l per / cnt) No 0.59 95.1 - - I. Poly-2.6-dichloro 0.57 94.3 1,4-phenylene oxide 2 Poly-2,6-diphenyl- 0.62 96.9 1,4-phenylene oxide 3 Poly-2,6-dimethoxy 1,4-phenylene oxide

*) In chloroform at 25 C.

109 582.

Claims (1)

Patent claims: I. Process for the production of stabilized polyphenylene oxides, d a d υ r c h g e k e η η 7 e i c h η e l. that a polyphenylene oxide of the general formula (I) R.