[0001] This invention relates to a molding resin, to a method of producing the molding resin
and to shaped articles formed from the molding resin. More particularly, it pertains
to molding resins comprising a polyarylene ester and a reinforcing filler, to a method
of producing such molding resins and to shaped articles formed from such molding resins.
[0002] Many polyesters have been suggested for use as molding resins and engineering thermoplastics
since the earliest practical development of such polymers by Whinfield and Dickson.
Although several of such polyesters and copolyesters have found commercial success
as film and fiber products, few have been successful as molding resins and engineering
thermoplastics. Two of the more successful, polyethylene terephthalate.and polytetramethylene
terephthalate prepared from aliphatic diols and terephthalic acid, suffer from certain
deficiencies as engineering thermoplastics. They are both quite flammable and have
rather low glass transition temperatures which can limit their usefulness to relatively
low temperatures.
[0003] The present invention discloses improved molding resins that yield molded articles
possessing a) improved fire safety performance, particularly reduced afterglow, b)
improved resistance to heat distortion and c) improved resistance to flow at elevatea
temperatures in comparison with reinforced polyalkylene terephthalates. According
to the present invention there is provided a molding resin comprising an intimate
blend of a
![](https://data.epo.org/publication-server/image?imagePath=1978/51/DOC/EPNWA1/EP78300028NWA1/imgb0001)
polyarylene ester and a reinforcing filler, the polyarylene ester consisting essentially
of units derived from a C
8 to C
25 aromatic dicarboxylic acid and a diphenol comprising from 60 to 100 mol percent 1,2-bis-(4-hydroxyphenyl)ethane
and from 40 to O mol percent of a C
6 to C
25 diphenol, said inherent viscosity of said polyarylene ester at 30°C, is at least
0.5 as determined at a concentration of 0.5 grams polyester per 100 ml solution in
a solvent mixture of 60 parts by weight of phenol and 40 parts by weight of sym-tetrachloroethane.
The present invention also provides a process of producing a molding resin comprising
the intimate blending of the polyarylene ester with the reinforcing filler and the
shaped articles molded from these molding resins.
[0004] The molding resins of the present invention comprise an intimate blend of a polyarylene
ester and a reinforcing filler preferably ranging from 2 to 60 weight percent of the
total composition. Such polyarylene esters consist essentially of units derived from
at least one C
8 to C
25 aromatic dicarboxylic acid and a diphenol comprising from 60 to 100 mol percent 1,2-bis-(4-hydroxyphenyl)ethane
and from 40 to 0 mol percent of at least one C
6 to C
25 diphenol.
[0005] The polyarylene ester component of the molding resin of the present invention is
the condensation product of at least one C
8 to C
25 aromatic dicarboxylic acid and a diphenol comprising from 60 to 100 mol percent 1,2-bis(4-hydroxyphenyl)ethane
and from 40 to 0 mol percent of at least one C
6 to C
25 diphenol. The polyesters are described in Belgian Patent 850,978 and have ,been found
to possess superior fire safety performance and are capable of yielding crystalline
compositions which have superior solvent resistance and stress cracking resistance.
[0006] While essentially any suitable C
8 to C
25 aromatic dicarboxylic acid and admixture thereof can be used in the preparation of
the polyarylene esters, the preferred aromatic dicarboxylic acids comprise at least
one acid of isophthalic acid, terephthalic acid, 3,3'-, 3,4'-and 4,4'- bibenzoic acids
and bis(carboxyphenyl)ethers, bis(carboxyphenyl) sulfides, bis(carboxyphenyl) sulfones,
bis(carboxyphenyl)methanes, 1,2-bis(carboxyphenyl)ethanes and 2,2-bis(carboxyphenyl)propanes
in which the carboxy groups are in the 3 or 4 positions. Mixtures of one or more of
the aromatic dicarboxylic diacids with minor quantities, generally less than 25 mol
percent, et C
2 to C
20 aliphatic diacids can also be' used. The quantities of aliphatic diacids in general
are selected so that they do not cause a significant loss in Tg of the resulting polyesters.
Prefer-
[0007] ably the quantity is limited to a loss in Tg of not more than 10°C. The acid or admixture
of acids is combined with 1,2-bis(4-hydroxyphenyl)ethane or with 1,2-bis(4-hydroxyphenyl)ethane
in admixture with essentially any other suitable diphenol or mixture of diphenols
to provide the aromatic polyesters of the present invention. Representative diphenols
comprise at least one diphenol of resorcinol, . hydroquinone, 3,3'-, 3,4'- and 4,4'-
diphenols, or diphenols represented by the formula:
wherein the hydroxyl groups are in the 3- or 4- positions, Y is 0, S, SO2, C=0, CH2, CH(CH3), C(CH3)2, (CH2)2 or (CH2)3 and R is H or a C1 to C4 alkyl radical and m = 0 to 4. Examples of diphenols according to formula I include
bis(4-hydroxyphenyl)methane, -1,2-bis(3-hy-, droxyphenyl) ethane, 1-(3-hydroxyphenyl)-2-(4-hydroxyphenyl)
ethane,2,2-bis(4-hydroxyphenyl)propane, bis(4-hydroxyphenyl)ether, bis(4-hydroxyphenyl)sulfide
and bis(4-hydroxyphenyl)sulfone.
While the diphenol must contain at least 60 mol percent 1,2-bis(4-hydroxyphenyl)ethane,
it is preferred to use a diphenol which comprises at least 90 mol percent, 1,2-bis(4-hydroxyphenyl)ethane
because these polyesters are generally crystalline and exhibit a rather rapid rate
of crystallization and polyarylene esters in which 1,2- bis(4-hydroxyphenyl) ethane
is substantially the only di- phenolic component
![](https://data.epo.org/publication-server/image?imagePath=1978/51/DOC/EPNWA1/EP78300028NWA1/imgb0003)
can be used to advantage to obtain more rapid rates of crystallization.
[0008] The inherent viscosity of the polyesters determined at 30°C. and in a solvent combination
of 60 parts by weight phenol and 40 parts by weight sym-tetrachloroethane at a concentration
of 0.5 g per dl, is at least 0.5 and is preferably at least 0.7. The selection of
acid and diphenol components is made so that the polyester preferably has a glass
transition temperature of at least 100°C. and a melt.viscosity at 350°C. determined
in a capillary rheometer at a shear rate of 100 sec
-1 of less than 10
5 poise. For.crystalline polyesters prepared by condensation of aromatic diacid and
diphenol comprising at least 90 mol percent l,2-bis(4-hydroxyphenyl)ethane, the aromatic
dicarboxylic acid is preferably selected so that the melting point of the polyarylene
ester is less than 350°C. A preferred group of the polyarylene esters comprises those
polyesters obtained by condensation of a diphenol comprising at least 90 mol percent
l,2-bis(4-hydroxyphenyl)ethane and a dicarboxylic acid comprising at least 67 mol
percent isophthalic acid. Of this group, One of the preferred combinationsis obtained
from 1,2- bis(4-hydroxyphenyl)ethane and isophthalic acid without additional components.
Such preferences are based on the availability and cost of the acid as well as on
the desirable glass transition and melting points of the resulting polyesters.
[0009] Since molding cycles are preferably rapid, it is desirable that a crystalline polyester
crystallize in the short period during which the polymer is cooling in the hold. Thus
a molding material for uses where high temperature dimensional stability is important,
needs to have a rapid rate of crystallization. The glass transition temperature, the
melting point and the rate of crystallization can be determined by means of differential
scanning calorimetry as described in Belgian Patent 850,978.
[0010] The crystallization rate is expressed as the inverse of the time required for one
half of the crystallization exotherm observed when a sample is cooled at a rate of
20
0C. per minute. A rate of crystallization of about 0.2 minutes
-1 or greater as determined by this method is satisfactory in injection molding of polymers
because the cooling rate in the molding operation is generally much faster than the
cooling rate used in the determination of rate of crystallization. However, a crystallization
rate of about 0.5 minutes
-1 or greater is more preferable and for rapid molding cycles a crystallization rate
of about one minute or greater is even more preferred.
[0011] The polyarylene ester component of the present invention can be produced by a convenient
method such as by melt condensation or solvent condensation of mixtures of aromatic
dicarboxylic acids and diphenol diesters selected to provide polyarylene esters of
the desired fire safety performance and processability. They can be produced by melt
or solution polymerization of selected mixtures of phenol esters of aromatic dicarboxylic
acids and diphenols and by interfacial polymerization of salts of diphenols and aromatic
dicarboxylic acid dihalides. Thus, while the combination is formally a condensate
of diacid and diphenol, in practice the reactants are diacids and diphenol esters,
or phenyl esters of diacids and diphenols, or salts of diphenols and diacid halides.
One method of preparation is the nelt condensation of mixtures of aromatic dicarboxylic
acids and diphenol diesters. Another method is the melt condensation of mixtures of
aromatic dicarboxylic acids and diphenol diesters' to a prepolymer stage of inherent
viscosity in the range of 0.1 to 0.4 followed by solid state polymerization to advance
the polymer to an inherent viscosity above 0.5.
[0012] The molding resins of the present invention are prepared by intimately blending the
polyarylene.ester with sufficient reinforcing filler which is generally from 2 to
60 weight percent of the total composition. Preferably, the amount of reinforcing
filler is in the range of from 5 to 40 weight percent of the total composition to
achieve a sufficient degree of reinforcement without an excessive increase in melt
viscosity. It is to be understood that the indicia of reinforcement are increases
in the tensile strength, stiffness or impact strength of the filled composition in
comparison with the unfilled composition.
[0013] In general, any reinforcement can be used such as granular, plate-like, acicular
or fibrous fillers of suitable size for reinforcement. The fillers may be metallic
such as aluminum, iron, nickel, copper or zinc or may be non-metallic such as carbon
filaments, silicates, clays, calcined clays, asbestos, silica, titanium dioxide, titanate
whiskers, glass flakes and fibers and the like.
[0014] The preferred reinforcing fillers include any kind of glass fibers usually used for
reinforcing thermoplastic resins and are relatively soda free glasses comprising lime-aluminum
borosilicate glass such as types "C" and "E" glass. The fibers may be in the form
of filaments, or bundled into strands, ropes or rovings and the like. They are conveniently
used in the form of chopped strands of up to 5 cm. in length and preferably in the
range of 0.3 cm.to 2.5 cm. in length. Other addi tives such as colorants, plasticizets,
stabilizers, hardeners and the like can be incorporated into the molding resins.
[0015] Blending of the polyarylene ester and the reinforcing filler is carried out in any
convenient way, such as by dry mixing pellets or powder of polyarylene ester with
the filler and melt blending and extrusion, or by adding filler to molten polyarylene
ester,.blending and extrusion. The polyarylene ester, the reinforcing filler and any
other additives are preferably as free as possible of water. Mixing is preferably
carried out in as short a time as possible to provide a sufficiently intimate and
uniform blend and at a temperature selected for adequate melt viscosity but insufficient
to cause thermal degradation of the resin. The blend can be extruded and cut up into
molding compounds such as granules, pellets, etc. by conventional techniques.
[0016] The molding resins can be molded in any equipment conveniently used for reinforced
thermoplastic compositions e.g., a 14 gm. Arburg machine with temperature in the range
of 250° to 350°C. and mold temperature of 100° to 150 C. can be used. Depending on
the molding properties of the polyarylene ester, the amount of reinforcing filler
and the crystallization behavior of the polyarylene ester, those skilled in the art
will be able to make the conventional adjustments in molding cycles to accommodate
the composition.
[0017] The invention is further illustrated but is not intended to be limited by the following
examples in which ratios of monomers are mol ratios and all other parts and percentages
are by weight unless specified otherwise.
EXAMPLE A
POLY(1,2-BIS(4-HYDROXYPHENYL)ETHANE)ISOPHTHALATE
[0018] A charge consisting of 8.2 parts of isophthalic acid and 14.8 parts of 1,2-bis(4-acetoxyphenyl)ethane
is placed in a reaction vessel equipped with a stirrer, con denser and receiver. The
vessel is evacuated and purged with nitrogen three times. A nitrogen blanket is maintained
in the reactor while it is heated to 250°C, for about three hours during which period
approximately 3.5 to 4.0 parts of acetic acid distills. Thereupon the vessel is evacuated
to a pressure of 125 mm. and heating at 275°C. is continued for one half hour during
which period an additional 1 to 1.5 parts of acetic acid distills, The vacuum is then
increased to reduce the pressure to about 0.1 to 0.2 mm. and the temperature is raised
to 290°C. for an additional hour. At this point the reaction mixture becomes so viscous
that further stirring is difficult. Heating is stopped, the reaction mixture is again
blanketed with nitrogen and allowed to cool. The resultant polymer is light yellow
in color, crystalline and demonstrates an inherent viscosity of 0.57 in the phenol-tetrachloroethane
solvent.
EXAMPLE B
POLY(1,2-BIS(4-HYDROXYPHENYL)ETHANE)ISOPHTHALATE
[0019] A similar reaction is carried out under the same conditions and with the reactants
and equipment described in Example A except that after the initial three hour period
the temperature is raised to 275°C. and the pressure is reduced to 125 mm. for 30
minutes. Thereafter, the temperature is raised to 290
oC. during the final period at high vacuum of 0.1 to 0.2 mm. The resultant polymer
demonstrates an inherent viscosity of 0.83 and is crystalline and a clear light yellow
in color.
EXAMPLES C - U
[0020] Examples C to U are carried out by reacting mixtures of diphenol diacetates and isophthalic
acid by the melt method of Example A, with adjustment in the temperature and heating
cycle appropriate for the rheology and morphology of the particular polyester or by
melt polymerization to a prepolymer followed by solid state polymerization of the
crystalline polyester. Compositions and physical property data are set forth in Table
1. Melt Viscosities are determined at 316°C. with a Sieglaff-McKelvey Rheometer at
a shear rate of 100 sec
-1, using a capillary with a length to diameter ratio of 25 to 1.
[0021] The data show that polyester combinations containing high levels of 1,2-bis(hydroxyphenyl)ethane
and acids such.as isophthalic acid are opaque and exhibit crystalline melting points
below 300°C. and crystallize rapidly while in contrast, polyester combinations containing
substantial amounts of other diphenols and polyester combinations containing substantial
amounts of substituted acids such as 5-t-butyl-isophthalic acid are amorphous.
[0022] Fire safety performance is conveniently determined by the Underwriter's Laboratory
"Test for Flammability of Plastic Materials - UL-94, September 17, 1973" using the
ratings which became effective February 1, 1974. The polyesters of 1,-2-bis-(4-hydroxyphenyl)ethane
are found to be superior in their UL-94.rating to polyesters containing a substantial
amount of bisphenol A(2,2-bis(4- hydroxyphenyl)propane.
[0023]
![](https://data.epo.org/publication-server/image?imagePath=1978/51/DOC/EPNWA1/EP78300028NWA1/imgb0005)
PREPARATION OF MOLDING RESINS
EXAMPLE 1
[0024] Polyisophthalate of 1,2-bis(4-hydroxyphenyl) ethane prepared as in Example C, is
extruded and chopped to yield pellets of approximately 3 to 5 mm in length and 2 mm
in diameter. 85 parts by weight of the pellets are blended in a tumble blender with
15 parts by weight of chopped glass strand, 4.8 mm length, containing 800 filaments
of .13 micron diameter per strand supplied by Owens Corning Fiberglas Corporation
under the trade name Owens-Corning Fiberglas 419. The blend of polyester and glass
fiber is force fed to the chopper of a single stage extruder heated to 320°C. and
is slowly extruded through the strand die. The strand is cooled and chopped to provide
pellets of molding resin.
[0025] The molding resin is injection molded in a 14 gm. Arburg machine at a temperature
of 315°C. and a mold temperature of 122°C. to provide test bars. The test bars are
tested for tensile strength and elongation, ASTM D-638; flexural strength and modulus,
ASTM D-790; impact strength ASTM D-256; heat distortion ASTM D-648. The data are presented
in Table 2.
EXAMPLES 2 and 3
[0026] Molding resins are prepared as in Example 1 with the polyisophthalate of 1,2-bis(4-hydroxyphenyl)ethane
and respectively 22.5 and 30 parts by weight of glass fiber per 100 parts by weight
of total composition. The molding resins are infection molded into test bars and subjected
to physical testing. The data are presented in Table 2.
![](https://data.epo.org/publication-server/image?imagePath=1978/51/DOC/EPNWA1/EP78300028NWA1/imgb0006)
[0027] Example 2 is subjected to the Underwriter's UL-94 test. The rating for samples 1.58
mm in thickness is V-0 (average flame out time within 5 seconds, no afterglow). In
comparison, the polyester of Example 2 without glass fibar reinforcement is rated
V-0 (average flame out time within 3 seconds with afterglow). A test bar of Example
2 with a heat distortion temperature of 183°C. was subject- . ed to a load in the
range of 0.14 to 0.28 kg cm
-2 for 20 minutes at 210°C. No flow or deformation occurs. In contrast, a. test bar
of a reinforced polytetramethylene tarephthalate, containing 30 weight percent glass
fiber, having a heat distortion temperature of 212°C, shows considerable flow and
deformation under similar conditions and fails the UL-94 test.
EXAMPLES 4 - 9
[0028] folding resins are prepured as in Example 1 by blending polyarylene ester Examples
K, L, M, N, P and R with 30 weight percent of the total composition of Owens-Corning
Fiberglas 419. The molding resins are molded into
![](https://data.epo.org/publication-server/image?imagePath=1978/51/DOC/EPNWA1/EP78300028NWA1/imgb0007)
bars. Considerable enhancement of the tensile strength, modulus and heat distortion
temperature is obtained in comparison with the unfilled polyesters.'
EXAMPLES 10 - 13
[0029] These examples are prepared for comparative purposes. A polyarylene ester similar
to Example U comprising the condensation product of bisphenol A and isophthalic acid,
of inherent viscosity 0.8 is blended with glass fiber in the manner described in Example
1. The molding resins thus obtained are molded into test bars and tested for physical
properties. Examples 10, 11 and 12 contain 15, 22.5 and 30 weight percent of glass
fiber; Example 13 is the unreinforced polyester. The data are presented in Table 3
and show that the heat distortion temperature of this polyester is relatively unaffected
by the reinforcing filler in contrast to the pronounced effect obtained in Examples
1-3 comprising the polyisophthalate of 1,2-bis(4-hydroxyphenyl)ethane.
![](https://data.epo.org/publication-server/image?imagePath=1978/51/DOC/EPNWA1/EP78300028NWA1/imgb0008)
EXAMPLES 14 - 16
[0030] Molding resins containing 30 weight percent glass fiber are prepared in the manner
of Example 1 from polyester Examples S and T. The molding resins are molded into test
bars. The tensile strength and modulus of the polyesters are. enhanced by the addition
of glass fiber. However, little improvement in heat distortion temperature is obtained.
1. A molding resin comprising an intimate blend of a polyarylene ester and a reinforcing
filler; the polyarylene ester consisting essentially of units derived from a C8 to C25 aromatic dicarboxylic acid and a diphenol comprising from 60 to 100 mol percent l,2-bis-(4-hydroxyphenyl)ethane
and from 40 to O mol percent of a C6 to C25 diphenol, said inherent viscosity of said polyarylene ester at 34°C. is at least
0.5 as determined at a concentration of 0.5 grams polyester per 100 ml solution in
a solvent mixture of 60 parts by weight of phenol and 40 parts by weight of sym-tetrachloroethane.
2.A crystallinemolding resin according to Claim 1 in which the melt viscosity of said
polyarylene ester at 350°C is less than 105 poises determined at a shear rate of 100 sec-1 with a capillary rheometer.
3. A molding resin according to either of Claims 1 or 2 in which said reinforcing
filler is a granular, plate-like, acicular or fibrous filler and comprises from 2
to 60 weight percent of the molding resin.
4. A molding resin according to any of the preceding claims in which said reinforcing
filler is a fibrous non-metallic filler.
5. A molding resin according to any of Claims 1 to 3 in which said reinforcing filler
is glass fiber.
6. A molding resin according to any of the preceding claims in which said aromatic
dicarboxylic acid comprises isophthalic acid, terephthalic acid t-butyl-isophthalic
acid, 3,3'-,3,4'- or 4,4'-bibe- zoic acid or a bis-(carboxyphenyl)ether, bis(carbc
phenyl) sulfide, bis(carboxyphenyl) sulfone, bis( carboxyphenyl) methane, 1,2-bis(carboxyphenyl)
ethane, or a 2,2-bis(4-carboxyphenyl) propane, wherein the carboxy groups are in the
3- or 4- positions.
7. A molding resin according to any of the preceding claims in which said C
6 to C
25 diphenol comprises resorcinol, hydroquinone, a 3,3'-,3,4'- or 4,4'- diphenol or a
diphenol represented by the formula
![](https://data.epo.org/publication-server/image?imagePath=1978/51/DOC/EPNWA1/EP78300028NWA1/imgb0009)
where the hydroxyl groups are in the 3- or 4- positions, Y is 0, S, SO
2, C=O, CH
2, CH(CH
3), C(CH
3)
2, (CH
2)
2 or (CH
2)
3, and R is H or a C
1 to C4 alkyl radical and n = 0 to 4.
8. A molding resin according to any of the preceding claims in which said C6 to C25 diphenol comprises hydroquinone, resorcinol, bis(4-hydroxyphenyl)methane, 1,2-bis(3-hydroxyphenyl)ethane,
1-(3-hydroxyphenyl)-2-(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl)propane, bis(4-hydroxyphenyl)ether,
bis(4-hydroxyphenyl) sulfide and bis(4-hydroxyphenyl) sulfone.
9. A molding resin according to any of the preceding claims in which said polyarylene
ester has a crystallization rate of at least 0.2 min-1.
10. A crystalline molding resin according to Claim 1 comprising from 2 to 60 weight
percent of the total composition of the reinforcing filler and said polyarylene ester
consisting essentially of recurring units represented by the formula
![](https://data.epo.org/publication-server/image?imagePath=1978/51/DOC/EPNWA1/EP78300028NWA1/imgb0010)
and having an inherent viscosity at 30
oC. of at least 0.7 as determined at a concentration of 0.5 grams polyester per 100
ml solution in a solvent mixture of 60 parts by weight of phenol and 40 parts by weight
of sym-tetrachloroethane.
11. A molding resin according to Claim 10 in which said reinforcing filler is a granular,
plate-like, acicular or fibrous filler.
12. A process of producing a molding resin according to Claim 1 comprising the intimate
blending of the polyarylene ester with the reinforcing filler.
13. A shaped resin article molded from a molding resin according to Claim 1."