CA1155596A

CA1155596A - Process for stabilizing polyarylates with an aromatic phenol

Info

Publication number: CA1155596A
Application number: CA000363255A
Authority: CA
Inventors: Louis M. Maresca
Original assignee: Union Carbide Corp
Current assignee: Union Carbide Corp
Priority date: 1979-10-29
Filing date: 1980-10-24
Publication date: 1983-10-18
Also published as: EP0028030B1; DE3068059D1; JPS5679124A; EP0028030A1; US4281099A; ATE7705T1

Abstract

ABSTRACT OF THE DISCLOSURE

Described herein is a process for preparing melt stable polyarylates having a reduced viscosity of from about 0.4 to greater than 1.0 dl/g which comprises reacting a diester derivative of a dihydric phenol with an aromatic dicarboxylic acid to produce a polyarylate having a reduced viscosity of from about 0.5 to greater than 1.0 dl/g, and then adding a stabilizing amount of an aromatic phenol to the polyarylate to form a poly-arylate substantially free of anhydride linkages.

Description

1 ~55~6 12,628 ~Z~
This invention is directed to a process for preparing melt stable polyar~lates having a reduced viscosity of from about 0.4 to greater than 1.0 dl/g which comprises reacting a diester derivative o a dihydric phenol with an aromatlc dicarbo~ylic acid to produce a polyarylate having a reduced viscosity of from about 0.5 to greater than 1.0 dl/g and then adding a stabilizing amount of an aromatic phenol to ~he polyarylate to form a polyaryLate substantially free of anhydride linkages.
Polyarylates are polyesters derived from a dihydric phenol, particularly 2,2-bis(4-hydroxyphenyl~-propane also identified as bisphenol-A, and an aromatic dicarboxylic acid, particularly mixtures of ~erephthalic and isophthalic acids. These polyarylates are high temperature, high per~ormance thermoplastic polymers with a good combination of thermal and mechanical pro-perties. They also have good processability which allows them to be molded into a variety of articles, Many processes have been described in the litera-ture for the preparation of polyarylates. One such process is the diaceta~e process. In the diacetate process, a dihydric phenol is converted to its diester derivative which is then reacted with an aromatic dicarboxylic acid to form ~he polyarylate.
A proposed reaction mechanism for the preparation of polyarylates by the diacetate process is illustrated for the reaction of bisphenol-A diacetate and a ~ixture of isophthalic and terephthalic acids:
~' 1 ~ 555~6 12,528 0=~ 0 .~ O
r,.
10=~

¦ ~ o ~1 O I _ 0=~ ~-0 ~=0 O
~-=0 ~ ,p 0=~

O ~ S ~ = ~
o T t~)--O
æ
. ~1 o = \
S
e~
_ ~ _ T

~$5~S~
12,628 In addition to producing the polyarylate (E), the reaction of iso and/or terephthalic acids ~B) and bisphenol-A diacetate (A) can produce anhydride ~F), either by way of .he inte~mediate mixed anhydride (C) or by the direct reaction of two molecules of the phthalic acid (B), accompanied by the loss of water . Due to the reactivity of anhydride, (F) 3 only a low equil-ibrium concentration of anhydride linkages will remain in the polymer backbone at the end of the reaction.
These anhydride linkages are believed to be labile enough to cause loss of molecular weight when the polymer is exposed to high temperatures~ i.e., 320-400C, ~hich are those needed to fabricate the polyaryLate.
Therefore, elimination of these anhydride linkages prior to processing the polyarylate is deemed nec-essary to help prevent the loss of molecular weight.
It has been surprisingly discoverad that the addition of an aromatic phenol at the end of the poly-arylate orming reaction eliminates the anhydride linkages and stabilizes it without significantly effecting the aromatic ester linkage.
U.S. Patent 4,011,196 describes the addition of a hindered phenol antio~idant or stabilizer in a small or stabilizing amount to a polyester resin-forming reaction mixture during the initial transesterification stage in which a zinc catalyst is used,or during the final polymeriza~ion stage before the desired intrinsic viscosity of the polymer is reached.
However, the tra~sesterification process des-cribed in thi~ reference would not produce anhydride li~55~ 12,628 linkages.
Japanese publication J5 0130-845 describes aromatic polyesters prepared from aromatic dicarboxylic acids and bisphenols mixed with 0.01 to 1 weight percent of phenolic stabilizers. An example in this pubLication describes the addition of 0.5 parts of 2,6-di-tert-butyl-4-methylphenol dissolved in acetone to an aromatic polyester derived from 2,2-bis(4-hydroxyphenyl)propane and a 1:1 terephthalic and isoph~halic acid dichloride mixture.
However, the interfacial poLymeriæation of this reference would not be expected to produce anhydride linkagesO
DESCRIPTION OF THE XNVENTION
The present invention is directed to a process or the preparation of a melt stable polyarylate having a reduced viscosity of from about 0.4 to greater than 1.0 dl/g, which comprises reacting a diester derivative of a dihydric phenol with an aromatic dicarboxylic acid, at a ~emperature o~ from about 260 to about 350C,to produce a polyarylate having a reduced viscosity of from about 0.5 to greater than 1.0 dl/g,and then adding a stabilizing amount of an aromatic phenol to the poly-arylate to form a polyarylate substantially ~ree of anhy-dride linkages; said aromatic phenol should be free o~
substituents in at least one of the positions ortho to the hydroxy group.

~55S~ 12,628 The present process comprises reacting:
(a) at least one diester derivative of a dihydric phenol having the following formula:
o (Y)z / (Y) O
R-C-0- ~ R' ~ R

wherein R is independently selected from an alkyl radical having from 1 to about 6 carbon atoms, preferably 1~ met;lyl, or a cycloalkyl radical having from 4 to about 7 carbon atoms, y is independently selected from alkyl groups of 1 to 4 carbon atoms, chlorine or bromine, z independently has a value of from 0 to 4, inclusive~
and R' is independently selected from a direct bondg a divalent saturated aliphatic hydrocarbon radical, particularly alkylene or alkylidene radicals having from 1 to 8 carbon atoms, especially C(CH3)2, cycloalltylene or cycloalkylidene radicals having up to and including 9 carbon atoms, 0, S, S0, SO2, and C0, x is 0 or 1; and (b~ at least one aromatic dicarboxylic acid, at a temperature of from about 260 to about 350C, to produce a polyarylate having a reduced viscosity of from about 0.5 to greater than 1.0 dl/g; and (c) adding a stabilizing amount of an aromatic phenol to the polyarylate to form a.polyarylate sub-stantially free of anhydride linkagesj said aromatic phenol being free of substituents in at least one of the positions ortho to the hydroxy group.
The diester derivative of the dihydric phenol is preparet by reacting a dihydric phenol with an acid .~l5-~5~ 12,628 anhydride derived from ~cids contRining from 2 to 8 oarbon atoms under conventional esterificatlon conditions.
The preferred acid anhydride iB acet$c anhydride~
Optionally,the dihydric phenol i~ reacted with the acid anhydride in the presence of an esterification catalyst, either in the presence or ~bsence of a solvent.
. The dihydric phenols that may be used ln this invention include the following:

2,2-bis-(4-hydroxyphenyl)propane, bis-(2-hydroxyphenyl)methan~, bis-~4-hydroxyphenyl)methanel bis-(4-hydroxy-2,6-dimethyl~3-methoxyphenyl)methane, 1,1-bis-(4-hydroxyphenyl~ethane, 1,2-bis-~4-hydroxyphenyl)ethane, 1,1-bis-(4-hydroxy-2~chlorophenyl)ethane, l,l-bis-(3-methyl-4-hydro~yphenyl)ethane, 1,3-bis^(3-me~hyl-4-hydroxyphenyl)propane~
2,2-bis-(3-pheny1-4-hydroxyphenyl)propane, 2,2-bis-(3-isopropyl-4-hydroxyphenyl)propane, 2,2-bis-(2-isopropyl-4-hydroxyphenyl)propane, 2~2-bis-(4-hydroxyphenyl)pentane,

3,3-bi~-(4-hydroxyphenyl)pentane, 2,2-bis-(4-hydroxyphenyl)heptane, 1,2-bis-(4-hydroxyphenyl)-1,2-bis-(phenyl)-propane,

4,4~(dihydroxydiphenyl)ether, 4,4'-(dihydroxydiphenyl)sul~ide, 4,4'~(dihydroxydiphenyl)sulfone, 4,4 ~(dihydroxydiphenyl)sul~oxide, 4,4'- dihydroxybenzophenone 4,4'- dihydroxybiphenyl 1 ~5~55S l2,62~

hydroquinone~ and naphthalene diol6.
These dihy~ric phenols may be used ind~vidually or in any c~m~ination which when rPacted with an aronatic dicarboxylic acid produce poly~rylate polymers that essentially do not crystallize during the reaction and reoovery steps. The preferred dihydric phenol is 2,2-bis~4-hydroxyphenyl)pr~pane, The aroma~ic dicarboxyllc acids tha~ may be used in this invention lnclude terephthalic acid, isophthalic acid, an~ of the nap~thalene dicarboxylic aci~ and mix-tures thereof, as well as alkyl substi~uted homologs of these carboxylic acids, wherein the ~lkyl group contains from 1 to about 4 carbon a~oms, and aeids containing o~her inert substituents such as halides, alkyl or aryl e~hers and the like. Preerably, mixtures of isophthalic and terephthalic aeids are used. The isoph~halic ac$d to terephthallc scid ratio in the mixture is abou~ 20:80 to about 100:0, while the most preferred acid ratio is about 25:75 ~o about 50:50. Also, from about 0.5 to about 20 percent of aliphatic diaeids containing from 2 ~o about 20 carbon atoms, such as adipic acid, ~ebacic acid, and the like,may be additionally used in ~he polymerization reaction.
The dihydri~ phenols and aromatic diearboxylic acids are selected ~o that ~he polyarylate produced re~in6 in an es6entially amorphous 6tate during the polymerization a~d recovery step.
A wide variety of aromatic phenols can be used herein including oligomeric and pol~meric aromatic phenols.

55~
1~,628 However, the aromatic phenol must have at least one of the positions ortho to the hydroxyl group free of substi-tuents. Also, the total number of unhindered hydro~y groups should not exceed three.
The aromatic phenols are selectecl from the following formulae:
(IH)b (I) (Ir)a (A)c wherein Ar is an aromatic radical derived fro~l a hydrocarbon such as be~zene, naphthalene and anthracene and containing 6 to 30 carbon atoms; a is an in~eger of ~rom 1 to 5; b is an integer of from 1 to 15 with the proviso that the number of unhindered hydroxy groups is at least one and should not exceed 3; c is equal to any remaining free position on the Ar radical, taking into account that there may be up to three hydroxy groups, each with one adjacent unsubstituted position;
A is a substiLuent which is non-rea~tive with the ester linkage o the polyarylate ~Ider the reaction conditions, such as halo, alkyL, aryl~ alkylene, arylene, alkylaryl, arylalkyl, -Oaryl, -Oalkyl, -OCOaryl, -OCOalkyl, -COOalkyl, O
-COGaryl,-~alkyl, -~aryl, -SO2aryl, -SO2alkyl, -S03-alkyl, -SO3- aryl~ wherein the aryl and arylene contains 6 to about 30 carbon atoms and the al*yl or alkylene contains 1 to about 8 carbon atoms;

5~5~
12,628 (~)d (OH)d , ,1 1 (A)c (A)c wherein Rl is lndependently an aromatic radical derived ~rom a hydrocarbon such as benzene, naphthalene and anthracene containing 6 to 30 carbon atoms; B is independently a di~ect bond or a divalent radical such as -0-~ -S-, -S-S-, -~-, -SO-, -S02-, -0-~-0-, alkylene, a~ylene, alkylarylene, arylalkylene, -~-alkyléne~
O ~ O C
-C~arylene-C-, -N-C-O-, -N-C-N- and the like, wherein the arylene contains 6 to about 30 carbon atoms and the alkyl-ene contains 1 to about 20 carbon atoms; A and c are as pre-viously defined; f and g are independently integers of ~rom 1 to 15; d is an integer of from 1 to 15, with the proviso that the number of unhindered hydroxy groups is at least one and does not exceed 3.
(OH)1-2 (III) ~
~,,~ (A)0_4 wherein A is as previously defined.
The preferred aromatic phenols include p-phenyl-phenol, p-cumylphenol, 4-hydroxybenzophenone, ~ naphthol, hydroxy terminated polysulfone, and hydroxy terminated polyethersulfone, The aromatic phenol is added to the polymerization reaction in a stabilizing amount, that is in amounts of rom 0.01 to about 10, and pre~erably, ~rom about 0.1 to about - 2.0 mole percent, based on the amount of the starting _ 9 _ 3 ~ 5 3 3 ~ ~i 12, 628 ~n~terisï~. The ~romat~c phenol :L8 opt~onally added in a solven~. The ~olvent~ discu~6ed, in~ra, are preferred.
The~e~actlon of the diester der$vative of ~ dihy dr~c phenol with ~he aromatic dicArbo:Rylic ~cid is c~rried out i~ ~he pre~ence .of from about 10 to ~lbout 6D,"
prefersbly from ~bout 25 to about 40~ and mo~t prefer-ably~ from about 30 ~co abouc 40 ~eight percen~, based on ~he weight of ~he pOly8rylflt2 produced3 of ~ ~olven~.
The ~ol~ent m~ay be a diphenyl e~her compound ~al~o lcnown ~s diphenyl ~xide3.
The diphenyl ether compound may be ~ul~s~c~tuted.
The~e ~ub~tituent6 are ~elec~ed from alkyl groups, chlorine" bromine or any 6ub~tituerlt which does not interfere with the polyaryla~e forming reaction or the reaction forming the diester derivati~e of the d~lhydr~c phenol.
o, the ~olvent may be a cycloaliphatic, fiub~ituted aromatic" ~r heteroaromatic compound, which conta~n~ ~t least one benzylic ~nd/or tertiary hydrogen 2 0 atom .
These compounds have a boiling point of from ~5~5~6 12,628 about 150 to about 350C, preferably from about 180 to about 280C, and most preferably from about 180 to about 220C, at atmospheric pressure. Additionally, these compounds have a solubility parameter, at a temperature of 250C, of + 4 within the solubility parameter of the polyarylate being produced. Solubility parameter is a measure for correlating polymer solvent interaction. It is defined in "Properties of Polymers", D. W. Van Krevelen, Elsevier Scientific Publishing Co., Amsterdam-Oxford-New York, 1976, pp. 141-155, as the square root of the cohesive energy density.
The cycloaliphatic compounds are of the following formulae:
~ R
\~1 (IV) 13 or;

(V) ~t~

wherein Rl is inde?er.~ently alkyl of 1 to 6 car-bon atoms, cycloalkyl of 6 to 18 carbon atoms, and a is an integer of 1 or 2.
The substituted aromatic compounds are of the following formuLae:

Ç~2)b (VI) ~

wherein R2 is independently alkyl of 1 to 6 car-bon atoms~ cycloalkyl of 6 to 18 carbon atoms and aralkyl ~55~
1~,628 or alkaryl of 7 to 18 carbon atoms and wherein the carbon atom of R2 attached directly to the benzene nucleus has 1 or 2 attached hydrogen atoms, and b i5 an integer of 1 to 6.
(R~)~

(VII) ~ ~2~n W11er~in ~3 i5 inde~endently alk.yl of 1 to 6 car-bon atoms, cycloalkyl of 6 to 18 carbon atoms~ c is an integer of 1 or 2, and n is an integer of 1 to 6.
L0 Th heteroaromatic compounds are of the following formula:
(R4~ d (VIII) ~

wherein A is S, 0, or -CH_~-, R4 is independently alkyl of 1 to 6 carbon atoms~ or cycloalkyl of 6 to 18 carbon atoms and wherein the ca~bon atom of R4 attached directly to ~he heteroaromatic nucleus has 1 or 2 attached hydrogen atoms, and d is an integer of 1 to 4.
The preferred compounds encompassed by structures ~V)through ~nI~ include xylenes, cumene, diethylbenzene, diisopropyl benzene~ tetrahydronaphthalene or decahydro naphthalene.
Additionally, the cycloaliphatic, substituted aromatic or heteroaromatic compounds may be used with up to 90 weight percent of other compounds such as diphenyl ether, dimethylsulfone, etc.

, - ~2 1~,628 l~e ~ImG~lt of ~aid ~olvents could vary during the polymerizatit~n reaction. For e~ample3 1~ may lbe advanta,geous to increase progre~siveïy the am~unt of these ~olvent~ to malntsin the reac~cion oledium ~t constant v~c~ity.
The reaction of the diester derivat~ve of ~he dihydric phenol with the aromatic dicarboxyliLc acid may lbe perfvrmed in the presence of a ca~alyst~
The use of a d~phenyl e~her ~olvent may be used with a magnesium catalyst.
The magnesium ca~alyst-iæ ~elec~ed from magne ium, magnesium oxide and a magne~ al~ of an ~n~rganic acid9 or organic acid or mi~ture~ ~hereo~. The 881t8 of the organ~c acid include acetate~ prDpior~ate~, benzoates, oxalateæ, acetylacetonates, or ~xtures thereo.

The catalyst may also include manqanese or æinc salt~s. The salts of the organic-acids inelude acetates, propionates, benzoa~es, oxalates,, ~cetylacetonstes, or mixtures thereof. The most preferred cataly~t i~ magne~lum ~cet~te. The cataly~t~ when used, i8 present ln the react~on ln a c~taly~ically effective am~unt ~hich can be, fDr example, from ~bout 1 to about 100~ preferably r~ about 10 to ~bout 50 parts per ~illion, b~sed on he weight vf the polyarylate produced.
The reaction Qf the die~ter d~rivative of the 11S~
12,628 dihydric phenol with the aromatic dicarboxylic acid is performed with these reactan~s present in the ratio of from about 0.85:1.00 to about 1.10:1.00, preferably from about 0.98:1.02 to about 1.02:0.98, diester derivative:
aromatic dicarboxylic acid.
The process of this invention is carried out at a temperature of from about 260 to about 350C and prefer-ablyg from about 275 to about 295C. The present process is generally conducted in an inert atmosphere (such as argon or nitrogen). The process is preferably carried out at atmospheric pressure although higher and lower pressures may be used. Obviously, at pressures higher than atmospheric pressure, higher temperatures will result.
The polymerization reaction is conducted for a period of time su~ficient to produce a polyarylate having a reduced viscosity of at least about 0.5 to greater than 1.0 dl/gm, which time is generally less than about 10 hours. The reaction time is generally in the range of from about 4 hours to about 8 hours, depending on the particular polyarylate being prepared. The addition of the aromatic phenol to the polymerization reaction causes a decrease in molecular weight. Therefore, the polymeriz-ation should be carried out until the reduced viscosity is above about 0.05 dl/g of the desired reduced viscosity and then the ar~matic phenol added to the polymerization.
Following this addition, the polymerization is continued for about 10 to about 180, and preferably, from about 10 to about 45 minutes.
The polymerization reaction of this invention may be carried out batchwise or continuously and by using any apparatus desired. Moreover, the reactants may be 1~555r)6 12,628 added to the polymerization zone in any way or order desired as long as the aromatic phenol is added after the desired molecular weight has been exceeded as deter-mined by having the reduced viscosity exceed the desired reduced viscosity by about 0.05 dl/g~
The diester derivative of the dLhydric phenol may be formed, in ~ L by adding the dihydric phenol together with the acid anhydride, an aromatic dicarboxylic acid and solvent to the reactor and the reaction carried out in a single reaction zor.e under combined esterification and poly-meriz~tion conditions as described above. Additionally, the dies~er derivative of the dihydric phenol may be flrst prepared and then an aromatic dicarboxylîc acid added to ~he same raaction vessel with the polymerization being carried ou~ under the conditions described above.
The polyarylate polymer having a reduced viscosity of at least about 0.4 dl/g is recovered in its final form by methods well known to those in the art, such as by direct devolatilization in an extruder under conditions sufficient to remove the solvent,coagulation~ spray drying, and the like.
The polyarylates may also be prepared by first forming a polyarylate prepolymer having a reduced viscosity of from about 0.1 to about 0.4 dl/gm, by reac-ting the diester derivative of a dihydric phenol with an aromatic dicarboxylic acid under the conditions des-cribed previously J for a reaction time of about 3 hours.
The polyarylate prepolymer may be added directly, after its formation, to a vented extruder wherein the molecular weight is increased to form a polymer having ~555~ l2,628 a reduced viscosity of from about 0.5 to greater than about 1.0 dl/gm. For example, the molecular weight of polyarylate prepolymer is increased in the extruder at a temperature of from about 300 to about 350C, under a vacuum of about 0.3 to about 2mm Hg and a residence time of from about 10 to about 30 minutes. The aromatic phenol can be added to the polymer in ~he extruder after the desired molecular weight has been exceeded as determined by having the redueed viscosity exceed the desired reduced viscosity by about 0.05 dl/g.
The process of this invention produces normally solid polyarylates having a reduced viscosity of from about 0.4 to greater th~n about 1.0, preferably from about 0.6 to about 0.8 dl/gm, as measured in chloroform (0.5 g/dl chloroform) or other suitable solvent at 25Co In those instances where the polyarylate is not soluble in chloroform, other solvents known in the art such as parachlorophenol, phenol/tetrachloroethane (60/40) 3 etc. may be used. Reduced viscosities of the polyarylates measured in these solvents generally have the same reduced viscosity range.
The polyarylates may be prepared in the presence of materials such as molecular weight regulators, anti-oxidants, and the like.
The polyarylates obtained b~ the process of this invention may be used together with the welL-known additives such as plastici~ers, pigments, lubricating agents, mold release agents, stabili2ers, inorganic fillers, and the 11ke. These polyarylates may also be blended with other polymers.

ss~s 12,628 EX~PIES
The following examples serve to give specific illustrations of the practice of ~his invention but they ~re not intended in any way to limit the scope of this invention. In these ex~mples, all parts and per-centage~ are on a weight basis unless otherwise 6pecif~ed.
Comparative Example A
A three neck, 250 ml round bottom flask was equipped with a mechanical stirrer, a nitrogen inlet and a vacuum jacketed vigreux column and distillation head. 31.20 g ~0.10 moles) of bisphenol-A diacetate, 8.30 g (0~05 moles) of isophthalic acid, 8.30 g (0.05 moles) of terephthalic acid and 10.74 g of diphenyl ether were charged to the flask. The system was purged with nitrogen for 1 hour at room temperature. While maintaining a constant nitrogen purge the reaction mixture was heated to between 260 and 270C. Acetic acid began to distill at this point. After one hour, the temperature was increased to between 290 and 300C. A partial vacuum (150 mm of Hg) was applied to the reaction after 2 hours at this temperature. The vacuum was reduced to <lmm of Hg in a stepwise fashion (50 mm/30 min.). After an additional one hour at 290-300C
and a full vacuum (~lmm of Hg) the system was allowed to cool to ambient temperature. The resulting polyarylate was ground and then dried under vacuum at a temperature of 120 to 130C for 24 hours.
The reduced viscosity of this polymer was measured in chloroform (0.50 gm/100 ml) at 25C and found to be 0.52 dl/g.

I~S55~ 12,628 The melt stability of the polymer was measured in a Tinius Olsen thermodyne (melt flow cell) at 375C. The polymer was added to the preheated (375C) chamber of the termodyne and put under a constant pressure of 44psi.
After 10 and 30 minutes at 375G,samples of the polymer were taken by allowing the polymer to flow freely from the bottom of the cavity. The reduced viscosity o~ these samples was measured in chloroform (0.50 gm/100 ml) at 25C and found to be 0~42 and 0.37 dl/g,respectively.
~
The procedure as described in COmparative Example A to prepare a polyarylate polymer was exactl~ repeated except that 30 minutes before the reaction was stopped~
the vacuum was released with nitrogen. A solution of 0.0085 g (5 x 10 5 moles) of p-phenylphenol in 1 ml o~
diphenyl ether was added to the vessel. The resulting mix~ure was stirred 15 minutes before a full vacuum (~1 mm of Hg) was reapplied. A~ter an additional 30 minutes under full vacuwm and a temperature of 290-300C, the reaction mixture was allowed to cool to ambient temperature.
The polymer was ground and d~ied as described in Comparative Example A. The reduced viscosity of this polymer was measured in chloroform (0.50 gm/100 ml) at 25C and ~ound to be 0.57 dl/g~
The polymer was then added to a Tinius Olsen thermo-dyne and tested by the procedure described in Compara-tive Example A. The reduced viscosity o~ the samples obtained after 10 and 30 minutes in the thermodyne were 0.58 and 0.52 dL/g, respectively.

5 ;~J ~
12,6~8 ,~
The proced~re o Example 1 ~8S exEIctly repeated except: ~hat 0.017 ~g (1 x 10 4 ~nole~) of p-pheny:Lphe~
was added ~n~tead of 0 . 0085 g of the p-phenylphenol The reduced vi~coslty of ~che polymer ~ormed ~nd the reduced viscosity of ~amples obtained ~f~er 10 ~d 3V
~inutes in the thermodyne are ~hown in the ~able~

The procedure of Example 1 was ex~c:tly repeated exa~ep~c that 0.039 g (2 x lO 4 9~01e6~ vf 4-hydroxybenzo~
pheno~e was added~.
The reduced ~i~cosity of the polymer ~ormed ,~nd the reduced vl;cosi~y of sample~ ob~alned ~fter 10 and 30 minute~ in the thermodyne are æhown in the Table.
E~
The procedure of Example 1 W8S exactly repeated except ltha~ 0.029 ~ (2 x lO 4 ll~oleæ~ o~ naph~hol was ~dded.
The reduced vi8s~0~1ty o~E ~he polymer formed ~nd the reduced vi cosi~cy of æanple~ obta:Lned ~f~er 10 and 30 minu~e~ in the thermodyne are ~hown in the Table.
~J e~ I
!

The procedure of Exampl~ 1 was 2xactly repeated except th~t 0.106 g (2 2c 10 4 moles) of octadeeyl 3- J
(3~ ,5'~ t-~utyl 41-hydroxyphe:lyl~ propr~or~ate (~r~nox 1079,* ~old by Ciba-Ge~gy Corporation) ~as ~dded.
The reduced ViSCofiity of the polymer formed ~nd the reduced vi~co~ity of ~amples obtained after lO and 30 minute~ in ehe thermodyrle are sho~n in ~he Ta~le.
.
*TradelTark = ~9 .~ .

~5 12,62 Com~arative Example C
The reactor sJstem consisted of a hot oil heated one gallon reactor fitted with a nitrogen inlet, mechan-ical agitator, and fractionating colu~n ~packed with ceramic saddles) connected to an overhead t~ke-off devlce consisting of a condenser and a receivPr.
The reactor was charged with 1200 grams of bisphenol-A
diacetate, 319.1 grams of isophthalic acld, 319.1 grums of terephtha~ic acid and 740 grams of diphenyl ether (35 weight percent based on the p~lymer produced). The reactor system was purged with nitrogen for 20 minutes and then the heater turned on to raise the temperatures of the reactor ~o abou~ 280C (the oil heater was set at about 300C~. Acetic acid star~ed to distill when the temperature of the mixture reached about 260C. Acetic acid distillatlon was followed by measuring its Level in the receiver. Ater about 3.0 hours at 280C, the power draw on the a~itator began to increase which indicated a viscosity increase. The reaetion was terminated after 5.5 hours at reflux by discharging the contents of the reactor under nitrogen. The reaction product was sllowed to cool to room temperature. ~le reaction product was ground to particles having an average size below l/4 inch and stored in an oven at 50-60C, for about 10-15 hours under a vacuum of 75 mm Hg. The poLymer was isolated by feeding the reaction product to a single srrew two vent extruder and flashing off ~he solvent. The barrel temperature of the extruder w~s 325C, the first vent was under a vacuum of about ~5.~5~
12,628 500 mm Hg, and the second vent was under a vacuum of about 15-20 mm Hg. The residence time of the polymer in the extruder was 2-5 minutes. The polymer had a reduced viscosity of 0.82 dl/g as measured in chloroform (0.50 gm/100 ml) at 25C.
The polymer was then added to a Tinius Olsen thermo-dyne and tested by the procedure as described in Compara-tive Example A. The reduced viscosity of the samples obtained after 10 and 30 minutes in the thermodyne were 0.72 and 0.66 dl/g, respectively.

Exam~e 5 The procedure as described in Comparative Example C to prepare a polyarylate polymer was exactly repeated except that 30 minutes before the end of the reaction, 1.31 g of p-phenylphenol in 20ml. of diphenyl ether was added.
The polymer produced had a reduced viscosity of 0.62 dl/g as measured in chloroform (0.50 gm/100 ml) at 25C.
The polymer was then added to a Tinius Olsen thermo-dyne and tested by the procedure as described in Compara-tive Example A. The reduced viscosity of the samples obtained after 10 and 30 minutes in the thermodyne were 0O59 and 0.55 dl/g, respectively.

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e~

O O

... . D n o CL ~0 n ~; -22-5~8 12,628 The data in the Table shows that without adding an aromatic phenol to the polymerization reaction, as in Comparative Examples A and C, there is a signi.ficant reduction in the reduced viscosity of the polymer after processing in the thermodyne for 10 and 30 minutes. The viscosity of the polymer prepared in comparative Example A, without aromatic phenol, is reduced 19.9 and 28.8 percent, respectively, after 10 and 30 minutes, while the viscosity of the polymer prepared in Comparative Example C, without aromatic phenol, is reduced 12.2 and 23 percent, respectively, after 10 and 30 minutes.
Further, when a hindered phenol, i.e., octadecyl 3-(3',5'-di-t-butyl 4'-hydroxyphenyl)propionate was used (Comparative Example B), no stabilization occurred.
However, when the aromatic phenol of this inven-tion is added to the polymerization reaction (Examples 1 to 4 and 6), the viscosity of the polymer is reduced only by a maximum of 6.7 percent after lO minutes, and only by a maximum of 15.6 percent after 30 minutes.
Therefore, when a polyarylate prepared with the aromatic phenol, according to the present invention, is molded or fabricated at the required molding temperature, it does not undergo the severe degradation as does the material prepared without aromatic phenol. Accordingly, no loss of properties is observed.

Claims

12,628 WHAT IS CLAIMD IS:

1. A process for preparing a melt stable poly-arylate having a reduced viscosity of frvm about 0.4 to greater than 1.0 dl/gm, which process comprises reacting:
(a) at least one diester derivative of a dihydric phenol having the following formula:

wherein R is independently selected from an alkyl radical having from 1 to about 6 carbon atoms, or cycloalkyl having from 4 to about 7 carbon atoms, y is independently selected from alkyl groups of 1 to 4 carbon atoms, chlorine, or bromine, z indepen-dently has a value of from 0 to 4, inclusive, and R1 is independently selected from a direct bond, a divalent saturated aliphatic hydrocarbon radical having 1 to 8 carbon atoms, a cycloalkylene or cycloalkylidene radical having up to and including 9 carbon atoms, O, S, SO, SO2, CO, x is 0 or 1; with (b) at least one aromatic dicarboxylic acid, at a temperature of from about 260 to about 350°C;
to form a polyarylate having a reduced viscosity of from about 0.5 to greater than 1.0 dl/g; and (c) adding a stabilizing amount of an aro-matic phenol to the polyarylate to form a polyarylate substantially free of anhydride linkages; said aromatic phenol being free of substituents in at least one of 12,628 the positions ortho to the hydroxy group and the total of unhindered hydroxy groups should not exceed three.

2. A process as defined in claim 1 wherein the diester derivative of a dihydric phenol has the following formula:

wherein y and z are as defined in claim 1.

3. A proeess as defined in claim 2 wherein each z is 0.

4. A process as defined in claim 1 wherein the aromatic dicarboxylic acid is a mixture of isophthalic acid and terephthalic acid.

5. A process as defined in claim 4 wherein the isophthalie acid to terephthalic acid ratio in the mixture is about 20:80 to about 100:0.

6. A process as defined in claim 1 wherein the aromatic phenol is added in amounts of from 0.01 to about 10 mole percent, based on the amount of the starting materials.

7. A process as defined in claim 6 wherein the aromatic phenol is added in a solvent.

8. A process as defined in claim 6 wherein the aromatic phenol contains at least one and not more than three unhindered hydroxy groups.

9. A process as defined in claim 6 wherein the aromatic phenol is selected from p-phenyl phenol, p-cumylphenol, 4-hydroxybenzophenone,.beta.-naphthol, hydroxy terminated polysulfone or hydroxy terminated polyethersulfone.

12,628

10. A process as defined in claim 1 wherein the reaction of the diester derivative of the dihydric phenol and aromatic dicarboxylic acid is carried out in the presence of from about 10 to about 60 weight percent, based on the weight of polyarylate produced, of a solvent.

11. A process as defined in claim 10 wherein the solvent is diphenyl ether.

12. A process as defined in claim 10 wherein the solvent is a cycloaliphatic,substituted aromatic, or heteroaromatic compound which contains at least one benzylic and/or tertiary hydrogen atom.

13. A process as defined in claim 12 wherein the solvent is selected from zylenes, cumene, diethybenzene, disopropyl benzene, tetrahydronaphthalene or decahydro-napthalene.

14. A process as defined in claim 1 wherein the reaction of the diester derivatives of the dihydric phenol with the aromatic dicarboxylic acid is performed in the presence of a catalyst.

15. A process as defined in claim 14 wherein the catalyst is selected from magnesium, magnesium oxide and a magnesium or zinc salt of an inorganic acid, or organic acid, or mixtures thereof.

16. A process as defined in claim 15 wherein the catalyst is magnesium acetate.

12,628

17. A process as defined in claims14, 15 or 16 wherein the catalyst is used in amounts of from about 1 to about 1000 parts per million,based on the weight of the polyarylate produced.

18. A process as defined in claim 1 which is carried out at a temperature of from about 275 to about 295°C.

19. A process as defined in claim 1 wherein the polyarylate produced has a reduced viscosity of from about 0.5 to about 0.8.

20. A process for preparing a melt stable polyarylate having a reduced viscosity of from about 0.4 to greater than 1.0 dl/gm which process comprises reacting:
(a) an acid anhydride derived from an acid containing from 2 to 8 carbon atoms;
(b) at least one dihydric phenol having the following formula:

wherein y is independently selected from alkyl groups of 1 to 4 carbon atoms, chlorine or bromine, z independently has a value of from 0 to 4, inclusive and R' is indepen-dently selected from a direct bond, a divalent saturated hydrocarbon radical having 1 to 8 carbon atoms, a cyclo-alkylene or cycloalkylidene radical having up to and including 9 carbon atoms, O, S, SO, SO2, CO, x is 0 or 1;
and 12,628 (c) at least one aromatic dicarboxylic acid, at a temperature of from about 260 to about 350°C, to form a polyarylate having a reduced viscosity of from about 0.5 to greater than 1.0 dl/g; and (d) adding a stabilizing amount of an arom-atic phenol to the polyarylate to form a polyarylate sub-stantially free of anhydride linkages; said aromatic phenol being free of subsituents in at least one of the positions ortho to the hydroxy group and the total of unhindered hydroxyl groups should not exceed three.

21. A process as defined in claim 20 wherein the acid anhydride is acetic anhydride.

22. A process as defined in claim 20 wherein the dihydric phenol has the following formula:

wherein y and z are as defined in claim 20.

23. A process as defined in claim 22 wherein each z is 0.

24. A process as in claim 20 wherein the aromatic dicarboxylic acid is a mixture of isophthalic acid and terephthalic acid.

25. A process for preparing a melt stable poly-arylate having a reduced viscosity of from about 0.4 to greater than 1.0 dl/gm, which process comprises the following steps:
I. Forming a polyarylate prepolymer having a reduced viscosity of from about 0.1 to about 0.4 dl/gm by reacting:
(a) at least one diester derivative of a 12,628 dihydric phenol having the following formula:

wherein R is independently an alkyl rad-ical having from 1 to about 6 carbon atoms or cycloalkyl having from 4 to about 7 carbon atoms, y is independently selected from alkyl groups of 1 to 4 carbon atoms, chlorine, or bromine, z inde-pendently has a value of from 0 to 4, inclusive, and R' is independently selected from a direct bond, a divalent saturated aliphatic hydrocarbon radical having 1 to 8 carbon atoms, a cycloalkylene or cycloalkylidene radical having up to and including 9 carbon atoms, O, S, SO, SO2, CO, x is 0 or 1;
with (b) at least one aromatic dicarboxylic acid at a temperature of from about 260 to about 350°C:
II. heating the prepolymer so formed in a vented extruder under vacuum at a temperature of from about 300 to about 350°C for a period of time sufficient to form a polyarylate having a reduced viscosity of from about 0.5 to greater than 1.0 dl/g; and III. adding a stabilizing amount of an aro-matic phenol to the polyarylate to form a poly-arylate substantially free of anhydride linkages;

12,628 said aromatic phenol being free of substituents in at least one of the positions ortho to the hydroxy group and the total of unhindered hydroxyl groups should not exceed three,

26. A polyarylate produced by the process of claims 1, 20 or 25.