DE2635101A1 - IMPROVED HIGH MOLECULAR POLYAETHERSULPHONES - Google Patents

Description

TLEDTKE - BüHLING ^m KlNNE - GROUP Patent attorneys:

Dipl.-Ing. Tiedtke Dipl.-Chem. Bühling Dipl.-Ing. Kinne Dipl.-Ing. Group

Bavariaring 4, P.O. Box 20 24 03 8000 Munich 2

Tel .: (0 89) 53 96 53-56

Telex: 5 24 845 tipat

cable. Germaniapatent Munich

4th August 1976

B 7517

ICI case Z / Pm 28939

ICI United States Inc. Wilmington, USA

Improved high molecular weight polyether sulfones

The invention relates to a process for the preparation of improved polyether sulfones.

Polyether sulfones are important and valuable polymers in the manufacture of films, panels and molded parts. SoI-ehe Polymers are normally made by reacting an alkali metal salt of a dihydric phenol with a 4,4'-dihalodiphenylsulfone compound manufactured. The alkali metal salt is usually by reaction of a strong base, for example Potassium or sodium hydroxide with a dihydric phenol obtain. In British patent specification 1,078,234 this is described above process, wherein bis-

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Dresdner Bank (Munich) Account 3939 844

Postal check (Munich) account 670-43-804

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phenol A is used. It is also from "British Patent 1,264,900 the conversion of a bisphenol A or a mixture of bisphenol A and an unsubstituted one Biphenol with an equimolar amount of a 4,4'-dihalodiphenyl sulfone known in the presence of potassium carbonate. This document shows that to achieve For polymers of desired molecular weight, the molar amount of potassium carbonate used is not less than that combined molar amount of dihydric phenol present

10 and the 4,4 ^f -dihalodiphenyl sulfone should be. The polymerization of the potassium _{diphenoxide salt of 3 * 3 'J} 5.5 ^f -tetramethyl-4,4'-biphenol with 4,4'-dichlorodiphenyl sulfone is also known. (Schultze: Advances in Chemistry Series (ACS) Vol. 91 , pp. 692-702) 1969)).

However, it can be found in the known publications

no indication that polyether sulfones with controllable molecular weights in the range between 20,000 to 125 were prepared from 3,3 ', 5,5'-tetraalkyl-4,4'-dihydroxybiphenyl using a stoichiometric excess of 0 to 30 % of an alkali metal carbonate or bicarbonate can be. Learner are according to the prior art of 3,3 ** 5,5'-tetraalkyl-4,4'-öihydroxybiphenyl-derived polymeric polyether sulfones with a density of not more than

ρ 25 1.20 g / cm not known.

It has now been found that if a 3,3 ', 5,5'-Tetraalky 1-4,4'-dihydroxybiphenyl with an essentially equal molar amount of a 4,4'-Dihalogendiphenylsulfonver ™ bond and about 0 to 30 % stoichiometric Excess of an alkali metal carbonate or bicarbonate is reacted in the presence of a dipolar, aprotic solvent, improved polymers are formed. The polymers not only have excellent high thermoforming temperatures and other advantageous properties, but the polymers produced by the process also have over-

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surprisingly, unusually low densities. These lower densities provide an obvious cost saving in the manufacture of films, plates or molded parts.

The invention is a method for

Preparation of a polyether sulfone polymer with a molecular weight of between 20,000 and 125,000, wherein an essentially equimolar reaction of a 3,3'-5,5'-tetraal- IQ kyl-4,4'-dihydroxybiphenyls with a 4,4'-EL halodiphenylsulfone compound or- _y icarbonats in the presence of d ipolaren aprotic and about 0 to 30% stoichiometric excess of an alkali metal _carbonate; liquid solvent performs.

Furthermore, according to the invention, a 3.3 ^f >

5.5 ^f -Tetraalkyl-4,4'-dihydroxybiphenyl-derived polyether sulfone polymer with a molecular weight of 20,000

2 to 125,000 and a density of not more than 1.20 g / cm

20 created.

The reactants which can be used according to the invention and which are to be critically selected are detailed below described.

That which can be used in the method according to the invention

3.3 ^l , 5.5 ^l -Tetraalkyl-4,4 ^t -dihydroxybiphenyl has the formula:

no - <\.

wherein R- ^, R ^, R- * and R ^ are alkyl groups which are the same or can be different.

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As used herein, the term "alkyl groups" refers to any monovalent radical derived from a saturated aliphatic hydrocarbon by the removal of a hydrogen atom therefrom. The term includes both straight chain and branched materials having 1 to about 12 carbon atoms. Preferred results are achieved with the alkyl substituents having 1 to about 5 carbon atoms. In the compositions of the invention, it is preferred to use symmetrical biphenyls, for example those in which the substituent R ₁ equals R ^ and Rp "equals Rh. A specific starting compound which most preferred is tetramethylbiphenyl (TMBP) in which the alkyl substituents are all methyl groups. Other biphenols which are useful include those in which the alkyl substituent can be ethyl, propyl, or sec-butyl. Under the term "molecular weight" is to be understood as the average molecular weight, unless otherwise stated.

The tetraalkylbiphenols used in the process of the invention are commercially available or can be prepared according to the teaching of US-PS 3 8o4 865.

The halogen atoms in the dihalodiphenyl compound are preferably chlorine atoms for economic reasons. The Plus derivatives are more expensive, but they cause polymer formation to occur at a faster rate. The bromine derivatives are comparable to the chlorine derivatives, however, the reaction temperature may require adjustment. The iodine derivatives generally react more slowly.

The alkali metal carbonate or bicarbonate is preferred Potassium carbonate, although other alkali metal carbonates such as sodium carbonate can also be used can. In the same way, the bicarbonates, for example potassium bicarbonate, can also be used in the process of the invention.

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can be used. The amount of carbonate or bicarbonate has been found to be critical in forming the desired polymers. It has been found that in particular a stoichiometric excess of about 0 to 30 % is essential in order to provide the polymers with the desired properties. Quantities smaller than 0 % stoichiometric excess give polymers with an undesirable, low molecular weight. Correspondingly, amounts in excess of 30 % yield polymers with molecular weights in excess of 125,000. Such polymers are difficult to process. The term “stoichiometric” is to be understood as meaning one equivalent of base per chlorine atom. The polyether sulfone product exhibits a combination of good properties including density, molecular weight, hardness, glass transition temperature, solution resistance, flexural and tensile strength. While properties such as low density, high glass transition temperature and solvent resistance characterize all polymers according to the invention, polymers with a higher molecular weight still show a slight increase in toughness., Optimal bending and tensile properties are found in polymers with a molecular weight of 30,000 to 80,000 .

The polymerization reaction times can vary and are dependent on the molecular weight desired.

For example to produce a polymer having low molecular weight (for example, 20 000), the one should be 2 hours the reaction at about 130 to 150 ⁰ C, and to proceed for about 4 to 5 hours at 150 ° to 170 ⁰ C. The polymers of higher molecular weight requires longer reaction times, generally 2k to 48 hours at 130 ° to 150 ⁰ C and further polymerization at 150 ⁰ 170 ⁰ C. Shorter times at a higher temperature are possible, but in view of possible adverse results, for example polymer degradation and undesirable color formation

not recommendable. Lower temperatures, for example 100 to 125 ° C, can reduce the reaction rate considerably.

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lent slow down. Preferred temperature ranges are 140 ° to 160 ° C, with reaction times between 4 and 100 Hours. Furthermore, when selecting the temperature for the reaction, the Take into account the boiling point of the solvent. Of course, the temperature of the reaction should never be in the substantially exceed the boiling point at atmospheric pressure. The polymerization is left at two, if desired Temperature levels progress to the removal of any Azeotrops that may be present during the reaction to facilitate. For example, the water-containing azeotrope at the lower temperature level to remove the Water to be distilled. The solvent can then be used again. To oxidative side reactions too avoid the polymerization is expediently in an inert atmosphere, for example under nitrogen carried out. The reaction is preferably carried out under conditions to eliminate any substantial amounts of water formed to remove.

The polymerization reaction requires the presence of a bipolar, aprotic reaction solvent. Specific solvents that can be used in the process of the invention include: dimethylacetamide, hexamethylphosphoramide, sulfolane, dimethyl sulfoxide and tetramethylurea. A particularly preferred solvent is dimethylacetamide. A sufficient amount of solvent should be used to allow adequate agitation of the reaction mixture during the polymerization process, particularly as the reaction mixture becomes more viscous, usually a ratio of 5 to 8 parts of solvent per one part of the biphenyl and 4,4'- Dihalodiphenylsulfone mixture appropriate. A larger amount of solvent should be used for the formation of higher molecular weight polymers. Water is easily formed in the polymerization reaction. When the water in amounts of about 0 5 _s to 1 wt -.% Of the reaction mixture is formed, it is advisable to remove this water, preferably by

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Distillation of a water-containing azeotrope present in the system. Can be Obwohl'eine variety of inert azeotropic bilr emissive organic liquids, such as benzene, xylene and chlorobenzene used for this purpose> ^ ^st ^ ^e - ⁿ preferably azeotrope formers toluene. In general, the amount of azeotrope former required is determined by the amount of water released during the reaction. Quantities of 25 to 33 wt -.% Of the amount of the solvent medium are considered to be appropriate to the

10 Keep the system sufficiently anhydrous.

If desired, the polyether sulfone polymers using a mixture of starting diphenyl monomers. For example, can 15Polymers can be made from a mixture of tetraalkylbiphenol with bisphenol A or thiodiphenol. The polyether sulfones, those made from such a mixture tend to have lower and higher glass transition temperatures Exhibit densities.

The polymer resulting from the process of the invention can be isolated, recovered and, if desired, according to cleaned using the usual techniques. For example, the solid polymer can be formed by high speed mixing of the polymer solution (A previous filtration of the polymer solution is optimal) with excess water or an organic non-solvents such as methanol or acetone can be isolated. Filtration, a thorough wash of the. Filter cake with water and vacuum drying provide an essentially salt-free polymer. Methanol and acetone are also valuable washing reagents for the removal of colored and low molecular weight impurities. Because Due to their high volatility, their use facilitates the drying of the solid polymers. Redeposition techniques can use selected polymer solvents, for example dimethyl acetamide, chloroform or pyridine in

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Combination with non-solvents, such as water, methanol or acetone, in addition to the reaction solvents lock in. A particularly preferred purification technique involves spontaneous reprecipitation from cyclic ones Ether with almost quantitative yields of the purified amorphous polymer. Those subjected to this cleaning technique After compression molding, polymers not only show increased tensile strength and flexural strength, but also have increased thermal resistance and an approximation of the molecular

10 weight range.

Cyclic ethers which are suitable for spontaneous redeposition include dioxane, tetrahydrofuran, 2-methy! Tetrahydrofuran, tetrahydropyran, epichlorohydrin, 1,3-dioxolane, 1,2-epoxypropane and ¹ 1,4'-dimethyl mdioxane.

The thermal stability of the polymer can alternatively or in addition to the spontaneous redeposition

2O by an additive, for example trisfnonylphenyl) phosphite or by extraction and subsequent redeposition be improved. The measurement of thermal influences by differential scanning calorimetry (DSC) and Visual examination of the compression molded polymers showed that the thermal stability can be improved by 25.degree.

The following examples serve to explain the invention in more detail. In the examples, all are percentages based on weight, unless otherwise stated.

The densities were determined by the air displacement method using a Beckman air compression pycnometer, model 930 determined. Glass transition (Tg) values were obtained by running a sample in the 990 Differential Scanning Thermal Analyzer "available from Du Pont-Instruments, analyzed. The analysis was carried out in a nitrogen atmosphere using a standard heating rate of 10 ° C / min. carried out.

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Example '1 (stoichiometric amount of KpCO,)

In a 3-neck reaction flask equipped with a 30 cm Vigreux column connected to a Dean-Stark trap and a vertical condenser were 6.05 g (0.025 mol) of tetramethylbiphenol, .100 ml of dimethylacetamide ,. 7.18 g (0.025 mol) 4,4'-dichlorophenyl sulfone, 3.45 g (0.025 mol) potassium carbonate and 30 ml toluene were used. the Batch was heated in a nitrogen atmosphere at 138-145 ° C for 64 hours while the toluene was heated at 105-133 ° C Untef ~ Hickfluss was boiled and the water of reaction was collected. That Toluene was then distilled off at pot temperatures of 150 ° to 165 ° C. for 3.5 hours. After cooling, that became Product deposited with 1.6 liters of water in a mixer.

The product was filtered and washed with water until it was essentially free of Cl ". The product was a dull white, spongy solid with low block density.

Examples 2-7

Examples 2-7 prepared according to the procedure

of Example 1 with various amounts of KpCO show the properties listed in Table I. As can be seen from Table I, in certain examples the product was additionally washed with methanol or acetone. In these examples, a product part was marked with either Washed 10 parts of methanol or acetone per polymer part. The polymer of Example 5 was made from a 5 # Pyridine solution precipitated again by adding 10 parts of water. The product of Example 6 was made from a 5 # Polymer solution in chloroform deposited again by adding 3 parts of methanol. Both the extra laundry and Reprecipitation techniques also improve the purity of the polymer by removing the low molecular weight and

35 colored by-products.

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Example 8 is a comparative example using of NaoII instead of KpCCL.

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Table I.

OO CD OO

Examples 1 ' _{2 3} 4th 5 6th 7th comparison
8th K ₂ CO ₃ O 5 10 15th 20th 26th 26th NaoH

(% stoichiometric excess)

Solvent-yes wash-I ^ O

Methanol acetone

yes yes yes yes yes yes

Yes

Yes / Yes

yes yes yes yes

Reprecipitation

Pyridine / H ₂ O - - - j'a - -

Chloroform/

Methanol """""J^a"

Yield {%) 100 97 9 ^ 92 88 82 92

MG 25,000 46,000 62,000 75,000 85,000 90,000 90,000 42,000

reduced viscosity (RV) 0.425 0.617 0.824 0.88 0.95 1.08 1.02 0.44 in 100 ml CHCl ₃ ) Tg. ( ⁰ C.) 250 ° 273 ° 270 ° 275 ° 270 ° 265 ° 275 ° 255 °

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Comparative example 8

24.22 g (0.1 mol) of TMBP were dissolved in a mixture of 49 g (44.5 ml) of dimethyl sulfoxide (DMSO) and 140 g (127 ml) of chlorobenzene in a 50 ml 4-necked flask equipped with a paddle stirrer, a thermometer, an N ₂ inlet tube, a dropping funnel and a fractionating column. The column was connected to a water separator and a condenser. The clear, amber solution was heated under a nitrogen atmosphere at 63-83 ⁰ C while 17.5 g of a 46.5% NaOH solution (0.20 equivalents) were added over a period of 7 minutes. The resulting thin slurry was stirred at 114 ° - 134 ^O C and heated water for 2 hours azeotropically removed. 44.5 ml additional DMSO was added while chlorobenzene was distilled off at 134-160 ° C. for one hour. A slurry was obtained. A heated solution of 28.72 g (0, l mol) of 4,4'-dichlorophenyl sulfone in chlorobenzene (30%) were added to the slurry at 155 ° to 158 ⁰ C over a period of 15 minutes. An additional 44.5 ml of DMSO was added while the separated solids dissolved. The final stage of the reaction was carried out at 156 ° -16O ° C. for 4.5 hours. During this time the viscosity of the slurry increased. The product was cooled and treated with 2 ml x methyl iodide at 125 ° C for 10 minutes to methylate the remaining phenolic hydroxyl groups. On cooling the product was obtained as a moist solid. The solid was mixed well with 1500 ml of HpO, filtered and washed free of chloride with water. The moist filter cake was then transferred to 1 liter of methanol, stirred well and filtered. The product was washed with methanol, air-dried and then ^{vacuum-dried at 120 °} C. and 1 mm mercury pressure for 3 hours. The polymer yield was 45.3 g (99.3 Ji).

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Some polyether sulfone polymers were compression molded into 76.2 mm diameter disks using a 50 fir press (Pasadena Hydraulics, Inc.). The electrically heated pressure rollers were used with the top rollers having a temperature of 315 ° C and the bottom rollers having a temperature of 299-31o ° C. The weight of each polysulfone polymer sample was 10 grams. The lubricant _was Fluorglide _> that from Chemplast Com. is available. The samples were heated for 10 minutes at 315 ⁰ C with no pressure, then 10 minutes at 315 ° C and 492 kg / cm ^2. The molded parts were removed at 85 ⁰ C.

The properties of the by the above procedure molded parts produced are shown in Table "II.

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example 1 Table II comparison
6 7 8 certainly. Density (g / cc.) 1.16 2 3 , 18 1.20 1.22 agreed. tensile strenght
(I / kg / cm) - 1.19 1.18 1, - 785 certainly. Compression stretch 2
(/ kg / cm ^) _ 845 815 Hardness 3 (Barcol) 18-23 1230 985 15-20 12 14-22 25-28 1> The tensile strength became according to ASTM-D-638 O
CD 2. The compressive strain became according to ASTM-D-790 I. CO
CD 3, The Barcpl hardness became according to ASTM-D-2583 CO 1046

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The polymers of the invention are also useful in the manufacture of films and extruded sheets. Standard solvent casting and extrusion techniques can be used here, as described, for example, in the Encyclopedia of Polymer Science and Technology, Interscience Publishers, Volume 6, pages 764-777.

Example 9 below illustrates the production of a film using a solvent cast method. Examples 10, 11 and 12 illustrate three techniques for improving thermal stability. Others improved Properties are listed in Table III.

Example 9

1.6 g of polymers _{3 /} prepared according to the procedure of Example 2 were dissolved in 64 ml of pyridine and filtered. The clarified solution was poured onto a glass plate inside a Teflon frame in a dry and dust-free CX atmosphere. A clear film with 38.1 μα thickness was obtained after 2k hours at a temperature of 65 ⁰ C. The film was tested and showed a tensile strength of 625

2 Ji?

kg / cm, a module of 2.2 xlCr kg / cm and an elongation of

4.5 %.
25th

Example 10 Purification by dioxane (spontaneous reprecipitation)

A sample of 50 g TMBP-Polyäthersulfon, which according to Example 3 was prepared and which by a solvent treatment step was cleaned with acetone at room temperature, is mixed with 930 ml of dioxane and 20 Minutem stirred long, after 20 minutes when most of the polymer The solution is passed through a Whatman filter paper # 4 and a layer of Super Cel filter aid filtered. The filtration is completed within 20-30 minutes. The filter cake is washed with 250 ml of dioxane.

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The combined filtrate is then gently stirred for 24 hours at room temperature. During this time, the purified polymer spontaneously reprecipitates. The product is filtered, washed with 300 ml of dioxane and 500 ml of methanol, and thereafter ° C / l6 hours at atmospheric pressure and at 8O ⁰ C / <1 mm for 68 hours at 65 dried. The product is obtained in 72% yield as a light yellow powder. The properties of the untreated and the dioxane-treated product (as amorphous powder and compression molded sample) are given in Table III below.

Table III Comparisons of a dioxane-treated and untreated

th Mn Polymers Example 10 MG Example 13 Dioxane treated M.G untreated 25 900 "ΉΓΓ 15 800 63 800 RV (CHCl _x ) 62 200 2.47 Tg ( ⁰ C) ^ 3.94 Cl (*) 0.872 Compression molding: 0.824 275 Tensile strength (kg / cm ² ) 270 0.14 Module (10 ⁴ kg / cm ² ) 0.38 Compression elongation (kg / cm) - 873 Elongation ( % ) 815 2.21 clarity 2.46 1480 colour 985 4.0 5.85. very good very good slightly amber Amber Colours Colours

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- 17 -, B 7517 Example 11 Tris (nony! Phenyl) phosphite additive

A sample of 15 g of TMBP sulfone with RV = 0.69, acetone-washed and prepared as in Example 2 of the invention, was mixed with 150 ml of acetone containing 0.15 g of tris (nonylphenyl) phosphite. The slurry is stirred and the solvent is allowed to gradually evaporate at room temperature. The product is then C / <1 mm 2 to 5 hours getrocknet.Sin Preßformling of this polymer was ⁰ at 70 at a higher 25 ° C temperature than in a control sample with no additive prepared. No thermal decomposition is noted in the treated sample. Some degradation is observed at the corners of the control sample. The DSC analysis showed that the beginning of the thermal influences in the treated sample was ^{25 ° C. higher than that of the control sample.}

Example 12 Extraction with subsequent redeposition

of the polymer

20th

14.5 g of a sample of an acetone-washed polyether sulfone, which was prepared according to Example 2, was dissolved in 300 ml of chloroform. The solution was extracted three times with 50 ml of 0.23 M H ₂ SO ₁₁ , followed by six extractions with

75 ml of water. The chloroform solution was then filtered through a filter aid layer. The polymer was precipitated by adding one part of the chloroform solution to two parts of rapidly stirred methanol. The polymer separates as a white solid and is filtered

30 and washed with methanol and acetone. The polymer is dried at 95 ° / <1 mm for 4 hours. The product has an excellent color. A Preßformling of this polymer was prepared ^aer at a 25 ° C higher temperature than a control sample, had a better color

35 and showed no thermal decomposition. The control sample

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showed some decomposition at the corners. The DSC analysis showed that the beginning of the thermal influences in the treated sample was ^{25 ° C. higher than that of the control sample.}

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Claims (8)

Claims 1. A process for the preparation of polyether sulfone polymers having a molecular weight between 20,000 and 125,000, characterized in that essentially equimolar amounts of a 3,3 ', 5,5'-tetraalkyl-4,4'-dihydroxybiphenyl and a dihalodiphenylsulfone compound are present in the presence an alipolar aprotic solvent and about 0 to 30 % stoichiometric excess of an alkali metal carbonate or bicarbonate. 2. The method according to claim 1, characterized in that that as dihalodiphenyl sulfone 4,4'-dichlorodiphenyl sulfone is used. 3. The method according to any one of claims 1 or 2, characterized in that the biphenol is 3,3 ', 5,5'-tetramethy1-4,4'-dihydroxybiphenyl is used. 4. The method according to any one of the preceding claims, characterized in that the alkali metal carbonate used is potassium carbonate, which is used in 5 to 26 % stoichiometric excess. 5. Polyether sulfone polymer made by a process according to one of claims 1 to 4. 6 .. Polymer according to claim 5, characterized in that it is derived from 3,3 ', 5,5'-Tetraalky1-4,4'-dihydroxybiphenyl and has a molecular weight of 20,000 to 125,000 and a density of not more than 1.20 g / cm x ³ . 7. Polymer according to one of claims 5 or 6, characterized in that it is made by spontaneous redeposition a cyclic ether. 709808/1046 - 20 - B 7517 8. Polymer according to claim 7, characterized in that that the cyclic ether is dioxane. 9 · Use of a polyether sulfone polymerizing according to Einach one of claims 5 to 7, produced by a method of claims 1 to 4 for moldings. 7 0 μ _t \ 0 8/1 0 k 6