Production of poly(arylene sulfide sulfone) with excess water to alkali metal sulfide

An improved process for producing poly(arylene sulfide sulfone) of increased molecular weight is provided. The process employs an Li salt of C.sub.1 -C.sub.20 carboxylic acid as a polymerization auxiliary and is carried out in an organic amide solvent by reacting a dihalogenated aromatic sulfone with an alkali metal sulfide in the presence of 10-15 moles of water per mole of the alkali metal sulfide at temperatures within the range of from 160.degree. C. to 230.degree. C.

This invention relates to a process for producing poly(arylene sulfide 
sulfone). 
Poly(arylene sulfide sulfone) materials are generally classified as 
amorphous, heat resistant resins and are expected to be useful in the 
production of electrical and electronic parts and automotive parts, as 
well as in fields where amorphous and heat resistance properties are 
required. 
Poly(arylene sulfide sulfone) may be prepared by a process comprising 
reacting a dihalogenated aromatic sulfone with an alkali metal sulfide 
such as sodium sulfide in an organic amide solvent such as N-methyl 
pyrrolidone. This process resembles the process for preparing 
poly(phenylene sulfide) disclosed in Japanese Patent Publication No. 
SHO-45-3368. However, the polymer produced by this of process is too low 
in molecular weight to be satisfactorily used in molding applications, in 
particular injection molding. Poly(phenylene sulfide) resin which is 
crystalline in nature may be cross-linked by controlled thermal oxidation 
in air to increase its molecular weight to a level at which it can be 
satisfactorily used in molding applications. Poly(arylene sulfide sulfone) 
which is amorphous in nature should be preferably subjected to further 
polymerization rather than thermal oxidation cross-linking in order to 
achieve an increased molecular weight suitable for use in molding, since 
it is expected to be useful in fields where clarity is important. The 
thermal oxidation cross-linking treatment tends to cause the resin 
material to discolor to an undesirable extent. 
Thus, there have been various processes for producing poly(arylene sulfide 
sulfone) with an increased molecular weight through polymerization rather 
than thermal oxidation cross-linking. For example, U.S. Pat. No. 4,016,145 
describes such a process in which an alkali metal carboxylate is added as 
a polymerization auxiliary in the polymerization system. U.S. Pat. No. 
4,127,713 discloses a process in which a sodium carboxylate is added as a 
polymerization auxiliary with water into the polymerization system. The 
latter U.S. Pat. states that although addition of water will adversely 
affect the desired increase in the molecular weight of poly(arylene 
sulfide sulfone) if a lithium carboxylate is added into the polymerization 
system, use of a sodium carboxylate will result in achievement of an 
increased molecular weight with the assistance of added water. Although, 
both these known processes are to some extent effective in increasing the 
molecular weight of poly(arylene sulfide sulfone), the resulting products 
have a level of increased molecular weight which is insufficient to allow 
them to be successfully used in forming and molding various articles, such 
as fibers, films, sheets and pipings. Consequently, a further increase in 
the molecular weight of poly(arylene sulfide sulfone) is needed. 
Japanese Patent Public Disclosure (KOKAI) No. SHO-62-190228 teaches the 
addition of water to the polymerization system in which poly(phenylene 
sulfide) is being prepared. However, the object and effect of the 
invention of this patent disclosure are different from those of the 
present invention. 
An object of the present invention is to overcome the above-discussed 
problem of molecular weight with the prior art poly(arylene sulfide 
sulfone) materials and, thus, to provide an improved process for producing 
poly(arylene sulfide sulfone) in which the polymerization is effected at 
temperatures between 160.degree. C. and 230.degree. C. using a lithium 
carboxylate auxiliary in the presence of a large proportion of water, i.e. 
about 10-15 moles of water per mole of the alkali metal sulfide reactant 
in the polymerization system, so as to significantly enhance the molecular 
weight increasing effect of the lithium carboxylate auxiliary that has 
been recognized to be unacceptably low in the prior art. 
Accordingly, the present invention provides an improved process for 
producing poly(arylene sulfide sulfone) comprising reacting a 
dihalogenated aromatic sulfone with an alkali metal sulfide in the 
presence of a polymerization auxiliary in an organic amide solvent, 
characterized in that the polymerization auxiliary used is a lithium 
carboxylate of the general formula: 
EQU RCOOLi 
(wherein R is an organic group having from 1 to 20 carbon atoms) and that 
the polymerization is effected at a temperature between 160.degree. C. and 
230.degree. C. in the presence of water in a proportion of from 10 to 15 
moles per mole of the alkali metal sulfide reactant in the reaction 
system. 
The invention will be described in more detail below. 
The polymerization auxiliary used in the process comprises one or more 
lithium carboxylates represented by the general formula: 
EQU RCOOLi 
wherein R is an organic group having from 1 to 20 carbon atoms. Examples of 
organic groups of 1-20 carbon atoms include alkyl, cycloalkyl, aryl, 
alkylaryl and arylalkyl groups having 1-20 carbon atoms and the 
above-listed groups containing one or more hetero atoms. Examples of 
lithium carboxylates which may be mentioned include lithium acetate, 
propionate, isobutyrate, butyrate, valerate, hexanoate, heptanoate, 
octanoate, nonanoate, n-decanoate, undecanoate, dodecanoate, 
octadecanoate, nonadecanoate, heneicosanoate, benzoate, toluylate, 
ethylbenzoate, cuminate, n-propylbenzoate, 2,3,4-trimethylbenzoate, 
2,3,4,5-tetramethylbenzoate, pentamethylbenzoate, naphthoate, 
anthracenecarboxylate, phenanthrenecarboxylate, phenylacetate and 
nicotinate and mixtures thereof. The lithium carboxylates may be used 
either in the anhydrous or hydrate form. The amount of the lithium 
carboxylate added in the process ranges from 0.05 to 4 moles, preferably 
from 0.1 to 2 moles, per mole of the alkali metal sulfide. If the lithium 
carboxylate is added in too small an amount, the molecular weight of the 
product polymer will not be increased to an acceptable level. On the other 
hand, use of the lithium carboxylate auxiliary in an unduly large amount 
would only add to the cost of production and would not be practical for 
industry. 
The water present in a proportion of 10-15 moles, preferably 11-14 moles, 
per mole of the alkali metal sulfide in the polymerization system 
according to the invention may be made up by externally added water and/or 
by hydration water of, for example the alkali metal sulfide and lithium 
carboxylate used. The water provided by the added water and/or the 
hydration water should be present, in total, in the specified proportion 
in the polymerization system, regardless of the relative proportions 
thereof derived from the added water and the hydration water. 
The dihalogenated aromatic sulfones which may be used in the invention are 
represented by the following formula (1): 
##STR1## 
where X and X', which may be the same or different, represent 
independently fluorine, chlorine, bromine or iodine; groups R.sub.1, which 
may be the same or different, represent independently hydrogen or an 
organic group having 1-20 carbon atoms; and Y represents SO.sub.2 or 
SO.sub.2 -Y'-SO.sub.2, where Y' is Ar or Ar-Z-Ar (wherein Ar is a divalent 
unsubstituted arylene group or an arylene group carrying C.sub.1-20 
organic groups(s), Z is O, S, SO, SO.sub.2, CR.sub.2 R.sub.3 or SiR.sub.2 
R.sub.3, where R.sub.2 and R.sub.3, which may be the same or different, 
represent independently hydrogen or a C.sub.1-20 organic group). 
Examples of the dihalogenated aromatic sulfones which may be used in the 
invention include 4,4'-difluorodiphenyl sulfone, 4,4'-dichlorodiphenyl 
sulfone, 4,4'-dibromodiphenyl sulfone, 4,4'-di-iododiphenyl sulfone, 
4-bromo-4'-fluorodiphenyl sulfone, 4-fluoro-4'-iodo-3-methyldiphenyl 
sulfone, 4,4'-dichloro-2,2'-dimethyldiphenyl sulfone, 
4,4'-dibromo-2,2',5,5'-tetramethyldiphenyl sulfone, 
4,4'-dichloro-2,2',5,5'-tetrapropyldiphenyl sulfone, 
2,2'-dibutyl-4,4'-difluorodiphenyl sulfone, 
4,4'-dichloro-2,2',3,3',5,5',6,6'-octamethyldiphenyl sulfone, 
1,4-bis(4-chlorophenyl sulfonyl)benzene, 2,4-bis(4-fluorophenyl 
sulfonyl)toluene, 2,6-bis(4-bromophenyl sulfonyl)naphthalene, 
1,5-bis(4-iodophenyl sulfonyl)-7-ethyl-naphthalene, 
4,4'-bis(4-chlorophenyl sulfonyl)biphenyl, 4,4'-bis(4-bromophenyl 
sulfonyl)diphenyl methane, 4,4'-bis(4-bromophenyl sulfonyl)diphenyl ether, 
4,4'-bis(4-chlorophenyl sulfonyl)diphenyl sulfide, 4,4'-bis(4-chlorophenyl 
sulfonyl)diphenyl sulfone, and 5,5'-bis[3-ethyl-4-(4-chlorophenyl 
sulfonyl)phenyl]nonane and mixtures thereof. 4,4'-Dichlorodiphenyl sulfone 
is preferred. One or more other dihalogenated aromatic compounds, for 
example p-dihalogenated benzenes, such as p-dichlorobenzene; 
m-dihalogenated benzenes, such as m-dichlorobenzene; o-dihalogenated 
benzenes, such as o-dichlorobenzene; dichloronaphthalene, 
dibromonaphthalene, dichlorobenzophenone, dichlorodiphenyl ether, 
dichlorodiphenyl sulfide, dichlorodiphenyl, dibromodiphenyl and 
dichlorodiphenyl sulfoxide may be used as additional comonomers in a 
proportion of less than 10 mole % with respect to the dihalogenated 
aromatic sulfone present. Provided that the linearity of the product 
polymer is not significantly disturbed, a minor proportion of 
polyhalogenated aromatic compounds containing three or more halogen atoms 
per molecule may be additionally employed. 
Examples of the alkali metal sulfides which may be used in the invention 
include sulfides of lithium, sodium, potassium, rubidium and cesium and 
mixtures thereof which may be used in the hydrate form. The alkali metal 
sulfide may be prepared by reacting an alkali metal hydrosulfide with an 
alkali metal base or reacting hydrogen sulfide with an alkali metal base. 
In the present process, the alkali metal sulfide may be formed in situ 
prior to introduction of the dihalogenated aromatic sulfone into the 
reaction system. Of course, the sulfide may be prepared outside the 
reaction system and then introduced to the system. Of the above-listed 
alkali metal sulfides, sodium sulfide is preferably used in the process. 
The organic amide solvent used in the invention may be cyclic or acyclic. 
Examples of solvents which may be mentioned include N,N-dimethyl 
acetamide, N,N-dimethyl formamide, hexamethylphosphoramide, 
N-methyl-.epsilon.-caprolactam, N-ethyl-2-pyrrolidone, 
N-methyl-2-pyrrolidone, tetramethyl urea and mixtures thereof. Of these, 
N-methyl-2-pyrrolidone is preferred. 
The polymerization temperature in the present process ranges from 
160.degree. C. to 230.degree. C., preferably from 190.degree. C. to 
210.degree. C. If the temperature is less than 160.degree. C., an unduly 
prolonged time is required to achieve an acceptable polymerization degree. 
Use of polymerization temperatures above 230.degree. C. will be 
accompanied with significant degradation of the resultant polymer. Due to 
this degradation, the polymerization degree achieved may remain low. The 
polymerization time depends on the polymerization temperature employed. 
The lower is the temperature, the longer the time required, while if a 
higher temperature is used, a shorter time will suffice. Generally, the 
polymerization time ranges from 10 minutes to 100 hours, preferably from 1 
to 15 hours. 
In the present process, it is preferable for the alkali metal sulfide and 
the dihalogenated aromatic sulfone to be employed in a molar ratio of from 
1.00:0.90 to 1.00:1.10 (alkali metal sulfide:dihalogenated aromatic 
sulfone). The proportion of solvent used may vary over a wide range, but 
preferably ranges from 3 to 30 moles of the solvent per mole of the alkali 
metal sulfide. 
By conducting the polymerization under the above-specified conditions, the 
product poly(arylene sulfide sulfone) is yielded in granular form. It is 
therefore possible to recover the product by simply filtering the reaction 
mixture. The recovered product may be conveniently washed with warm water. 
By conducting filtration, the organic solvent can also be recovered so 
that it may be reused in the process. 
The product poly(arylene sulfide sulfone) according to the present process 
should comprise at least 90 mole % of the structural unit of the following 
formula (2): 
##STR2## 
wherein groups R.sub.1 and Y are as defined hereinbefore. 
The product polymer may optionally comprise less than 10 mole % of the 
total structural units of comonomeric units, for example, p-phenylene 
sulfide unit 
##STR3## 
m-phenylene sulfide unit 
##STR4## 
o-phenylene sulfide unit 
##STR5## 
phenylene sulfide ketone unit 
##STR6## 
phenylene sulfide ether unit 
##STR7## 
diphenylene sulfide unit 
##STR8## 
and the like. 
Because the present poly(arylene sulfide sulfone) product is linear in its 
macromolecular structure and also is desirably increased in molecular 
weight, it is very suitable for use not only in injection molding but also 
in extrusion molding of such articles as fibers, films, sheets, pipings 
and the like. If necessary, the polymer may be mixed with an additive 
before use, for example, reinforcing fillers, such as ceramic fibers 
(e.g., glass, carbon or alumina fibers), aramide fibers, wholly aromatic 
polyester fibers, metallic fibers and whiskers (e.g., of potassium 
titanate); inorganic fillers such as calcium carbonate, mica, talc, 
silica, barium sulfate, calcium sulfate, kaolin, clay, pyroferrite, 
bentonite, sericite, zeolite, nepheline syenite, attapulgite, 
wollastonite, ferrite, calcium silicate, magnesium carbonate, dolomite, 
antimony trioxide, zinc oxide, titanium oxide, magnesium oxide, iron 
oxides, molybdenum disulfide, graphite, gypsum, glass beads, powdered 
glass, glass balloons, quartz, quartz glass; and organic and inorganic 
pigments. 
Further, conventional additives, for example, mold release agents, silane 
or titanate coupling agents, lubricants, heat stabilizers, weathering 
agents, nucleating agents, blowing agents, corrosion inhibitors, 
ion-trapping agents, flame-retardants and flame-proofing aids may be 
incorporated, if necessary. 
If desired, the poly(arylene sulfide sulfone) product of the present 
invention may be blended with one or more of homopolymers and random or 
block-graft copolymers based on, for example, polyethylene, polybutadiene, 
polyisoprene, polychloroprene, polystyrene, polybutene, poly 
.alpha.-methylstyrene, polyvinyl acetate, polyvinyl chloride, poly 
acrylates, polymethacrylates, polyacrylonitrile, polyamides (e.g., nylon 
6, nylon 66, nylon 610, nylon 12, nylon 11, nylon 46), polyesters (e.g., 
polyethylene terephthalate, polybutylene terephthalate, polyarylate), 
polyurethanes, polyacetals, polycarbonates, polyphenylene oxide, 
polyphenylene sulfide, polysulfones, polyethersulfones, polyaryl sulfones, 
polyether ketones, polyether ether ketones, poly(phenyl sulfide ketone), 
polyimides, polyamide imides, silicone resins, phenoxy resins and fluorine 
resins.

EXAMPLE 
The invention will be illustrated in more detail with reference to the 
following examples which are presented only for illustrative purposes and 
the invention is in no sense limited thereto. 
In the Examples, the reduced viscosity was determined at a temperature of 
30.degree. C. in a solution containing 0.5 g of polymer per each 100 ml of 
a mixed solvent comprising phenol and 1,1,2,2-tetrachloroethane in a 
weight ratio of 3:2. 
EXAMPLE 1 
A one liter-capacity autoclave was charged with 0.4 moles of sodium sulfide 
(Na.sub.2 S.2.8H.sub.2 O), 0.4 moles of 4,4'-dichlorodiphenyl sulfone 
(referred to as DCDPS hereinafter), 400 g of N-methyl-2-pyrrolidone 
(referred to as NMP hereinafter), 0.2 moles of lithium acetate and 3 moles 
of distilled water (H.sub.2 O/Na.sub.2 S ratio=10.3). The temperature was 
raised to 200.degree. C. and the mixture was allowed to react for 5 hours. 
On completion of this 5-hour polymerization, the reaction system was 
cooled and the reaction mixture was filtered. The resulting polymeric 
product was washed repeatedly with warm water and once with acetone and 
dried overnight under heat and vacuum to give while granular 
poly(phenylene sulfide sulfone) in a yield of 99%. The polymer showed a 
reduced viscosity of 0.65. 
The reaction conditions and results are summarized in Table 1. 
EXAMPLES 2-8 
The general procedure of Example 1 was repeated with various water 
proportions (H.sub.2 O/Na.sub.2 S molar ratios), polymerization 
auxiliaries, temperatures and times. The results are set forth in Table 1. 
COMATIVE EXAMPLE 1 
In an autoclave, 400 g of NMP, 0.765 moles of sodium sulfide (Na.sub.2 
S.2.8H.sub.2 O) and 0.383 moles of lithium acetate were mixed. The mixture 
was heated to 205.degree. C. to distill off 20.5 g of water along with 3.1 
g of NMP. Thus an H.sub.2 O/Na.sub.2 S molar ratio of 1.3 was achieved in 
the system. After cooling to 100.degree. C., the system was charged with 
0.75 moles of DCDPS and an additional amount (100 g) of NMP. The system 
was reheated to 200.degree. C. and allowed to react at this temperature 
for a period of 5 hours. 
Except for the above, the procedure of Example 1 was repeated. The results 
are shown in Table 1. 
The resulting polymer was powdery. The yield was 94%. The polymer had a 
reduced viscosity of 0.11. These results are suggestive of the fact that 
where the ratio of water to sodium sulfide has been unduly reduced due to 
dehydration of the reaction system, the molecular weight increasing effect 
of the polymerization auxiliary lithium acetate is seriously diminished. 
COMATIVE EXAMPLE 2 
The procedure of Example 1 was repeated except that the addition of 
distilled water was omitted (H.sub.2 O/Na.sub.2 S=2.8). The results are 
shown in Table 1. The resulting polymer (at 97% yield) was powdery and 
exhibited a reduced viscosity of 0.43. These results are suggestive of the 
fact that, although the molecular weight of the polymer of this 
Comparative Example was increased to some extent by the addition of 
lithium acetate, its reduced viscosity was unsatisfactorily low in 
comparison with those of Examples 1-8 and a further increase in the 
molecular weight would be necessary before the polymer could be 
successfully used in molding applications. 
COMATIVE EXAMPLE 3 
The procedure of Example 1 was repeated except that distilled water was 
added in an amount of 2 moles instead of 3 moles (H.sub.2 O/Na.sub.2 
S=7.8). The results are shown in Table 1. The product polymer was 
granular. The yield was 99%. The polymer had a reduced viscosity of 0.34. 
Although the proportion of water was increased in this Comparative Example 
as compared with Comparative Example 2, the molecular weight increasing 
effect of the lithium acetate was poor and not acceptable. 
COMATIVE EXAMPLE 4 
The procedure of Example 1 was repeated except that distilled water was 
added in an amount of 6 moles instead of 3 moles (H.sub.2 O/Na.sub.2 
S=17.8). The results are shown in Table 1. The resultant polymer was in 
the form of agglomerates. The yield was 99%. The polymer had a reduced 
viscosity of 0.53. This Example indicates that when an excessive 
proportion of water is present in the polymerization system, the 
polymerization auxiliary lithium acetate becomes less effective in 
increasing the molecular weight of the resulting polymer. 
COMATIVE EXAMPLE 5 
The procedure of Example 3 was repeated except that the polymerization 
stage was conducted at a temperature of 140.degree. C. for a period of 15 
hours. The results are shown in Table 1. A powdery polymer was obtained in 
a yield of 97%. The polymer had a reduced viscosity of 0.42. The results 
are indicative of the fact that a lower reaction temperature results in a 
poor increase in the molecular weight. 
COMATIVE EXAMPLE 6 
The procedure of Example 3 was repeated except that the polymerization 
temperature was 240.degree. C. The results are shown in Table 1. A powdery 
polymer was obtained in a yield of 96%. The polymer had a reduced 
viscosity of 0.38. This Example illustrates that excessively high 
polymerization temperatures adversely affect the action of increasing the 
molecular weight of the polymer. 
COMATIVE EXAMPLE 7 
The procedure of Example 3 was repeated except that the sodium acetate was 
used in place of the lithium acetate. The results are shown in Table 1. 
The polymer was obtained in a yield of 99% and granular. The polymer had a 
reduced viscosity of 0.44. This Example shows that sodium acetate is less 
effective in increasing the molecular weight of polymer than lithium 
acetate. 
COMATIVE EXAMPLE 8 
The procedure of Example 3 was repeated with omission of the polymerization 
auxiliary. The results are shown in Table 1 below. A granular polymer was 
obtained in a yield of 99%. The polymer had a reduced viscosity of 0.30. 
This Example illustrates that the addition of water in the absence of the 
lithium carboxylate auxiliary is not effective in achieving a polymer with 
a molecular weight that is increased to a useful extent. 
TABLE 1 
__________________________________________________________________________ 
charged charged 
polymeri- 
charged monomers polymeri- 
auxiliary/ 
zation 
polymeri- 
DCDPS/NMP Na.sub.2 S/DCDPS 
H.sub.2 O/Na.sub.2 S 
zation 
Na.sub.2 S 
tempera- 
zation reduced 
(moles/ (moles/ (moles/ 
auxil- 
(moles/ 
ture time yield 
visco- 
1000 g) moles) moles) 
iary*.sup.2 
moles) 
(.degree.C.) 
(hrs.) 
(%) 
city 
__________________________________________________________________________ 
Ex. 1 
1.0 1.0 10.3 AcOLi 
0.5 200 5 99 0.65 
Ex. 2 
1.0 1.0 11.5 AcOLi 
0.5 200 5 99 0.68 
Ex. 3 
1.0 1.0 12.8 AcOLi 
0.5 200 5 98 0.76 
Ex. 4 
1.0 1.0 14.5 AcOLi 
0.5 200 5 99 0.58 
Ex. 5 
1.0 1.0 12.8 AcOLi 
0.5 160 10 98 0.61 
Ex. 6 
1.0 1.0 12.8 AcOLi 
0.5 220 3 99 0.63 
Ex. 7 
1.0 1.0 12.8 AcOLi 
0.5 160 5 99 0.71 
200 2 
Ex. 8 
1.0 1.0 12.8 BzOLi 
0.5 200 5 97 0.60 
Comp. 
1.5 1.02*.sup.1 
1.3 AcOLi 
0.5 200 5 94 0.11 
Ex. 1 
Comp. 
1.0 1.0 2.8 AcOLi 
0.5 200 5 97 0.43 
Ex. 2 
Comp. 
1.0 1.0 7.8 AcOLi 
0.5 200 5 99 0.34 
Ex. 3 
Comp. 
1.0 1.0 17.8 AcOLi 
0.5 200 5 99 0.53 
Ex. 4 
Comp. 
1.0 1.0 12.8 AcOLi 
0.5 140 15 97 0.42 
Ex. 5 
Comp. 
1.0 1.0 12.8 AcOLi 
0.5 240 5 96 0.38 
Ex. 6 
Comp. 
1.0 1.0 12.8 AcONa 
0.5 200 5 99 0.44 
Ex. 7 
Comp. 
1.0 1.0 12.8 -- -- 200 5 99 0.30 
Ex. 8 
__________________________________________________________________________ 
*.sup.1 Since dehydration of the reaction system was effected, Na.sub.2 S 
was increased by 2% to compensate for the loss thereof that was expected 
to be caused by decomposition during the dehydration. 
*.sup.2 Ac = acetyl and Bz = benzoyl. 
From the foregoing, it is apparent that the present process for producing 
poly(arylene sulfide sulfone) is characterized by the presence of water in 
a proportion as large as 10-15 moles per mole of an alkali metal sulfide 
reactant in an organic amide solvent and also the selection of suitable 
polymerization temperatures within a specified range, by the enhanced 
molecular weight increasing effect exerted by lithium carboxylate 
auxiliary. The poly(arylene sulfide sulfone) materials produced according 
to the process are expected to be useful in production of various 
articles, such as electrical and electronic parts and automotive parts, as 
well as in other industrial fields where amorphous and heat resistance 
properties are required, because their increased molecular weight permits 
them to be successfully employed in injection and other molding processes.