DE1962677C3 - Process for the production of polyphenylene oxides - Google Patents

Description

(A)

are built up and whose terminal hydroxyl groups are converted into substituents which are inactive towards oxygen at elevated temperatures, characterized in that the polymers are repeating basic units of the formula

CH., - CH - R "

-ophenyl or methylphenyl. R, represents methyl or phenyl.

5. The method according to claim I. characterized in that Rj and R _v (ür MliIivI and R- _{n is} phenyl.

6. The method according to claim 1, characterized in that P .., and R _{b is} phenyl and \ füi methyl.

7. The method according to claim 1, characterized in that R _h and R _{1 is} phenyl and R _{1 is} methyl.

8. The method according to claim 1, characterized in that R.,. R _h and R, represent phenyl.

(B) The invention relates to polyphenylene oxides stabilized against thermal degradation with a mean molecular weight of at least 10 (too. those made up of basic units of the formula

CH,

contain, where R _{a is} methyl or phenyl and R _h door phenyl. Is chlorophenyl or methylphenyl and the B units are 1 to 20 mol percent of the total amount of Α units and B units and have an average molecular weight in the range from 10,000 to 30,000.

2. Polyphenylene oxides according to claim 1, characterized in that the Α units are 2,6-dimethyl-1,4-phenylene oxide units and the B units are 2 - methyl - 6 - (n - phenyl ether) -1.4 - phenylene oxide units.

3. Polyphenylene oxides according to claim!, Characterized characterized in that the A units are 2-methyl-6 ■■ phenyl-1,4-phenylene oxide units and the B units, 2- methyl- 6- (n-phenylethyl) -1,4-phenylene oxide units are.

4. Process for the preparation of compounds according to Claims I to 3 by oxidative coupling of a phenol of the formula

R.,

are built up and their terminal H \ dro \\ l- »Groups are converted into substituents, which at increased Temperatures are inactive to oxygen. which are characterized in that d'e polymers always recurring basic units of the formula

CH, -CH-R _h

40 R.

OH

V ''

wherein R., is methyl or phenyl and then the I hydroxyl end groups of the copolymer in substituents, which at elevated temperature are stable to oxygen, characterized in that the phenol the form! A during the oxidative union with 1 to 20 molar props of a phenol of the formula

OH

R.

R ₁ ,

ClI.,

copolymerisieri, where R _{h is} phenyl. Chlorine, where R., for methyl or phenyl and R _h for phenyl. Sees chlorophenyl or methylphenyl and the B units are 1 to 20 mole percent of the total amount of the A units and B units and an average molecular weight in the range of K) O (K)

(A) 5 ° to 30,000.

It was found that such compounds are more resistant to discoloration at elevated temperatures than masked polymers which are not secondary . (- carry carbon atom.

Polyphenylene oxides, sometimes also called Polyphenylenülher represent, as a general class, an extremely interesting group of novel ones Polymers. These polymers, and / were both homopolymers and copolymers as well their manufacturing processes were in their own US patents 33 Od X74 and 33 06X75 geol'feiibarl. These polyphenylene oxides have numerous interesting properties, which is why they are also used for

(B) have found numerous commercial / widespread uses. In general, these polyphenylene oxides are poly (2.6-disubstituted-1.4-phenylene oxides, which are male by oxidative association on 2.6-disulfide phenols.

for use at high temperatures in the presence of Luit or other oxygen-rich Case should include these polyphenylene oxides as shown 1.31. preferably be masked. d. h .. it should be yours terminal hydroxyl group can be converted into an oxidative substituent. This can be done using The general procedures are done as they apply to masking hydroxyl blocked polymers find: but preferably this is done by warm masking, as in the US patent 3D 75 228 is described, whereby likewise all developing hydroxyl groups are developed and masked. The observation was, however, accepted masked polyphenylene oxides, which have an alkyl substituent at the benjolkcrn, are somewhat involved Oxygen react. Are these compounds more quickly in the presence of an oxygen hall When exposed to high temperatures, these alkyl groups themselves are slowly oxidized and thereby caused crosslinking and slight discoloration of the polymer.

An investigation of various alkyl substances on the basic phenylene oxide periods showed that those containing a secondary - / - carbon atom, For example, carry an isopropyl, isobutyl or - / - Phenyläthylsubstiluenten against this oxidative Are more prone to attack than straight-chain alkyl groups. which contain a primary - (- carbon atom. For example the polymer of 2,6-diisoprop \ I-phenol is more susceptible to this oxidative attack than the polymer of 2-methyl-6-isopropylphenol. which in turn is more susceptible to oxidative attack than the polymer of 2,6-dimethylphenol. This Copolymers are also susceptible to oxidative attack. those made from these phenols be watching. It was therefore surprising when it was found that a masked Polyphenylene oxide copolymer. which was made from a mixture of phenols, of which at least one phenol has a substituent with a secondary carbon atom and the other is phenol did not have such a substituent, were more stable to discoloration at elevated temperatures {ils polymers or copolymers made from phenols that have alkyl groups. which only contained primary «carbon atoms. This was all the more surprising as for the unmasked Copolymers the opposite is true. Furthermore, it was found that in the event that the secondary «Carbon atom had a phenyl group bonded directly, as for example in the </ - phenylethyl, the effect on the copolymers was stronger than in in the event that the substituent was completely aliphatic, such as in isopropyl.

The amount of phenol with a secondary '/ carbon atom required for the copolymer only has to be Between 1 and 20 mole percent of the total amount of phenol amount to the Hei position of the polyphenyl, noxide copolymers is oxidatively combined, surprisingly it was found that the copolymers which contained 3 to 6 mol percent of this phenol, for reasons not yet known had a lower glass wall limit temperature than the copolymers. which contained smaller or larger quantities and lower molding temperatures allowed.

Although can be used for the production of polyphenylene phenols two sckundäre '/ include carbons, such phenols give the same relatively large amounts ^' ^ ^"ι ^ ^{Ρ Γα. 1ιεηί1εη} diphenoquinones This tendency to form diphenoquinones is in animal division of Copolymers, although reduced, are still clearly present, which is why it is more expedient, but not necessary, to use phenols which have only one substituent which carries a secondary carbon atom.

The masked polyphenylene oxide copolymers. which have been shown to be thermally stable are those masked copolymers in which 1 to 20 mole percent of the base periods of the copolymer 2,6-disubstituted phenylene oxide units in which one or both substituents have a secondary '/ -Carbon atom and the rest of the basic periods from 2,6-disubstituted phenylene oxide units in which one substituent is straight-chain alkyl and the other substituent is straight-chain Is alkyl or aryl. In order for such copolymers to have useful properties, should these copolymers had an average molecular weight of at least 10,000,000 Polyphenylene oxides have basic periods of the formula

and the formula

R,

IH)

on. wherein R is a straight alkyl radical. straight-chain ilalogenoalkyl radical in which the halogen is located on a carbon atom other than the «/ carbon atom or denotes a straight-chain aralkyl radical in which the aryl radical is located on a carbon atom other than the carbon atoms. R _{1 has} the same meaning as R and also denotes aryl or halogenatedaryl, R ₂ denotes alkyl, including aralkyl, which has a secondary - (carbon atom and R- denotes one of the substituents delineated _{by R 1 and R-. For R. R 1.} R, and R, are typical examples of substituents and methods of making them are disclosed in the aforementioned U.S. patents.

An increase in the chain length of the substituents on the benzene nucleus of the basic phenylene oxide periods does not give the polyphenylene oxides any prominent ones Properties compared to the properties obtained when the substituents are one have a lower number of carbon slol atoms.

In addition, many phenols with longer-chain substituents are not as easily accessible as those with shorter chain length. As stated above, aralkyl groups are. the a secondary have κ-carbon atom, more effective than alkyl groups, which have a secondary carbon atom. Furthermore, a Substiuienl favors with a secondary «carbon atom the

Formation of diphenoquinone not to the extent that two such substituents do. Therefore According to the invention, such polyphenylene oxides are from the large group described above preferred, the masked polyphenylene oxide copolymers having a number average molecular weight of at least 10,000 and their base periods both the formula

CH ₃

IO

O-

(A)

like the formula

CH ₃ -CH

20th

(B)

where R _{a is} methyl or phenyl, R _{b is} phenyl, chlorophenyl or methylphenyl and the B units are 1 to 20 mol percent of the total number of Α units and B units.

These copolymers are, as already stated above was produced by the oxidative combination of the corresponding phenols. The ones for making of the polyphenylene oxides required phenols, which have the basic periods A, are 2,6-Dimethylphenyl (2,6-xylenol) and 2-methylethylphenylphenyl The first phenol is readily available as a by-product of the carbonaceous substance or by direct means Methylation of either phenol or o-cresol is available, while the latter is readily available through phenol direct methylation of o-phenyl phenol (2-phenyl phenol) is to be obtained, with the high selectivity of the o-Mcthylierumg in its own German patent 12 63 010 is disclosed and claimed. For the production of polyphenylene oxides with that of the form! B corresponding basic periods are easy by reacting styrene or the corresponding chlorinated or methylated nuclei Styrene with either o-phenylphenol or o-cresol with formation of 2-phenyl -6- (n-phenylethyl) -phynol. 2- methyl-6 - («- phenylethyl) phenol or the abovementioned phenyl ether-substituted phenols accessible, wherein the Phenylkcm the Phcnyliithyl-Substilucnlen 1 to 5, preferably 1 to 2 Having chlorine or methyl substituted such. B. 2 - methyl - 6 - [α - (4 - chlorophynyl) - ethyl] phcnol or 2 - Methyl - 6 - [α -1 (2,4 - dimethylphynyl) - ethyl] phcnol.

In the preparation of the copolymers, the individual phenols either before the oxidative combination be mixed, or one of the phenols can be oxidatively combined and the other phenol or the other phenols are then added to form segmented copolymers. in the In general, the oxidative cleaning reaction is carried out in that air or another oxygen-containing Gas in a solution of a basic copper (II) amine complex in an inert solvent, how /. B. in toluene or benzene, is introduced, you · likewise either the oxidatively to be connected Contains phenols or to which the phenols are slowly added to the reaction mixture Further details of this oxidative union reaction can be found in the aforementioned US patents can be removed.

After the oxidative union is finished. the catalyst residue is removed or inactive fourth, for example by washing out the copolymer solution with water, which generally contains an acid to remove the catalyst, and furthermore by adding a strong gelling agent, by adding a precipitant for copper or by precipitating the polymer from the reaction mixture. Since the masking reaction takes place in a solution of the polymer, the catalyst is generally separated from the solution of the polymer or inactivated in the solution, so that the polymer does not have to be dissolved again before masking.

The masking reaction is carried out to remove the to convert terminal hydroxyl groups into substituents against a sauersteffhaltige atmosphere are inert at elevated temperatures. To mask the polyphenylene oxide copolymer can Various means are used, for example, can be carried out on the hydroxyl groups Reacting with acid anhydrides or acyl halides ester groups are formed. Ether substituents can through implementation with ethereal means. such as B. dimethyl sulfate, alkyl halides in the presence a base and copper are introduced. You can decolorize and reposition with at the same time masked with an alkali metal adduct of a diaryl ketone and then made to react with numerous masking agents. You can can also be thermally masked with numerous masking agents, as in that already mentioned above US Patent 33 75 228 is described, which has the additional advantage that the resulting Hydroxyl groups are formed and masked at the same time.

Before or at the same time as masking, the copolymer can be treated with a metal and an alkanoic acid. This method leads when applied to the inventive Copolymers for the production of the masked polyphenylene ether copolymers and for an end product, which has the highest light permeability after a predetermined period of heat aging.

The invention is described in more detail below with reference to the examples, in which, if not something else specifically noted is all parts and percentages based on weight and weight Temperature degrees Celsius.

Example I.

This example demonstrates the general procedure that is used to make the copolymers finds. In a vigorously stirred solution of 0.1 g of copper (I) chloride, 0.59 g of trimethylamine, 0.15 ml Ν, Ν, Ν ', Ν'-Tetramcthylcndiamine and 100 ml of benzene, in which 10 g of anhydrous magnesium sulfate are suspended oxygen was introduced. After the copper (I) chloride was completely dissolved, were 10 g of the total weight of the mixture of phenols dissolved in 30 ml of benzene over a period of time slowly added over a period of 15 minutes. The addition of

Phenol solution led to a liner exothermic reaction. In general, the reaction was continued until the molecular viscosity of the polymer 0.6 dl / g in chloroform at 25 °. This was done with the help of a calibrated pipette, for which a Calibration table had been prepared showing the dependence of the outflow time from the pipette on the showed the limiting molar viscosity of the polymer in the solution. In general, there was a response time for this 90 minutes after all the phenol has been added.

To obtain an unmasked sample of the copolymer, designated nc in the tables below is, part of the reaction mixture was poured into methanol, which with aqueous hydrochloric acid »5 solution was acidified to precipitate the polymer, which then redissolved and precipitated several times and then filtered off and dried. To obtain a sample of the polymer that is used at Ambient conditions had been masked and designated ac in the following tables a portion of the polymer solution is treated with enough diethylene triamine to pass the copper catalyst through To inactivate chelation of the copper ion. After filtering the polymer solution, so much lithium ketyl became of the benzophenone was added until the color of the ketyl persisted in the solution. This implementation converts all hydroxyl groups of the polymer into their corresponding lithium salts. Based on the amount of the lithium reacted with the polymer was an excess of the calculated amount of acetic anhydride is added to acetic acid ester with the hydroxyl groups of the polymer to form (acetate masked). This masked polymer was then poured into the Polymer solution isolated in methanol, redissolved and precipitated several times, filtered off and then dried.

If copolymers were heat-masked so that not only the hydroxyl groups present were masked, ₄ c but also the hydroxyl groups that formed were developed and masked, which are denoted by hc in the following tables, the polymer was first isolated as mentioned above, dissolved in benzene, acetic anhydride is then added to the solution, this is placed in a pressure vessel and heated ^{to 250 ° C. for 15 minutes.} After cooling, the polymer was isolated in the manner described above.

The use of acetic anhydride to mask the polymers shows the effect of masking. Similar results are obtained when the other sequestering agents described above are used in place of acetic anhydride. In some of the following examples, the polymer was masked at ambient conditions and then the effect of this dual treatment was determined by warm masking. These polymers are designated ac + he in the tables below. ^ ⁰

In the following examples, the stabilization effect was i.e. the resistance to discoloration at elevated temperatures, determined by that the time was recorded in hours after which the light transmission 0.32 to 0.37 mm thick films made from these polymers after heat aging in an oven with air circulation was reduced to 80% of the original value. The result is in the following Tables referred to as "hours to 80%" This procedure balances all differences from the original Value that depends on whether the polymer has been masked or not. For example, improved masking the original light transmission of the polymer at ambient conditions. It would therefore be an inadmissible comparison if one were to use the method to achieve a certain level of light transmission Compare the time required for the masked and unmasked polymer would because even if the two polymers were aged at the same rate, i. H. the would have the same stability, the masked polymer until this particular value is reached would take a long time. The values for the control are those for the homopolymer of the phenol, for example 2,6 - dimethylphenol, comparable values that do not have the d? .s secondary-u-carbon atom Contains carrying substituents used for the preparation of the copolymer of the example would. A comparison of the value for the copolymer and the homopolymer shows the improvement in stability against heat aging that could be achieved by producing the copolymers and likewise the need to mask the copolymer.

Example 2

A copolyphenylene oxide containing, as an essential ingredient, 1 mole percent fundamental periods, the Substituents with a secondary r <carbon atom had, was prepared by oxidative combination of 2,6-xylenol, the 1.6 mole percent 2-methyl-6- (r £ -phenylethyl) -phenol contained. The results after heat cooling are shown below in Table I listed.

table

Hours up to 80%

nc ac + he

Control Copolymercs 10
6th

35
42

If this example is repeated while reducing the amount of 2-methyl-6 - (<; - phenylethyl) phenol to 0.58% the copolymer did not give a better result than the control homopolymer, whereby It could be seen that at least 1 mol percent is required to achieve an improvement in stability are.

Example 3

Example 2 was repeated with the modification that the amount of 2-methyl-6 - («- phenylethyl) phenol in various copolymers on (a) 1.75. (b) 3.0, (c) 6.0 and (d) 12.6 mole percent, respectively. Another copolymer Ie) was made from 2,6-dimethylphenol produced, the 10 mole percent 2-phenyl-6- (ii-phcnylüthyl) -phenol contained. The results are shown in Table II below.

609 611/155

Table 11

hours to StI " " 35 nc IK 5X 34 control IO K) 52 58 Copolymer (al K) 19th 55 Copolymer (bl S. 24 65 Copolymer Ieι T 3 X 73 C'opolymeres Id ι -) 55 74 Copolymer (ei ->

Similar results are also obtained if instead of the 2,6-xylene in the above examples 2-phenyl-6-methylphynyl is used. Likewise, similar results are obtained when the corresponding phenols which, instead of the r / -Phcnyliithylsubsiituierten of the above phenols n- (chlorophenyl-ethyl of the above examples and << - (methylphenyl-ethylsubstituents can be used as the phenol having a substituent with a secondary! (- has carbon atom. Stable copolymers are obtained even if the amount of the phenol containing a Suhstituenten with a secondary "carbon atom up to 20 mol-per / ent was increased. If this limit is exceeded, the stability decreases. why a Exceeding this amount does not bring any advantages.

The color-stabilizable polyphenylene oxides according to the invention can be used for all of the above US patents mentioned uses of the polyphenylene oxides, z. B. serve as molding compounds for the production of molded products, fibers and films, which, if desired, by solution or melt spinning or can be crystal-oriented with the help of casting processes. Because of their improved Color instability after heat aging can make them especially useful for manufacturing, as shown above

ίο the above products are used, the are to be exposed to elevated temperatures during their use.

Various modifications can also be made. For example, before the

'5 final shaping in the composition fillers, dyes, pigments, lubricants and others Stabilizers are installed. Since the polymers are in many readily available solvents, such as z. B. xylene, benzene or chloroform are soluble.

Solutions of these polymers can be used to make protective coatings on substrates or a to form electrical insulation on metallic conductors.

The limit molar viscosity of the polymer of 0.6 dl g mentioned in Example 1 corresponds to the number average molecular weight (Ai _n ) of 30,000. B. osmometrically determined number average molecular weights of a series of samples against the also determined limiting molar viscosity of these samples on double logarithmic paper one obtains a straight line which allows the determination of the number average of the molecular weight corresponding to the limiting molar viscosities.

Claims (1)

Patent claims: i. Polyphenylene oxides stabilized against thermal degradation with an average molecular weight of at least 10,000, consisting of basic units the formula CH ₁