Note: Descriptions are shown in the official language in which they were submitted.
Backqround Of The Invention
Field Of The Invention
The present invention relates to a high impact
polyamide composition. More particularly, the
present invention is concerned with a polyamide
composition comprising at least one polyamide having
a specific relative viscosity in sulfuric acid, at
least one ethylene ionomer resin and at least one
monoepoxy or carbonate compound. The polyamide
composition may further comprise an elastomeric
olefin copolymer, an elastomeric styrene copolymer,
and/or a polyvalent alcohol. The polyamide composi-
tion has excellent mechanical strength and thermal
resistance properties so that it can advantageously
be employed in the manufacture of various automobile
parts and sporting goods. The polyamide composition
also has excellent impact strength, especially
excellent weld-line impact strength.
Discussion Of Related Art
Heretofore, various polyamide compositions
having improved impact strength have been proposed.
For example, these include a polyamide composition
comprising a polyamide and, blended therewith, an
ethylene ionomer resin (see, for example, U.S.
Patent No. 3,845,163 and Japanese Patent Application
7~7
Publication Specification No. 54-4743/1979), and a
polyamide composition comprising a polyamide and,
blended therewith, an ionomer resin or an elastomer
having a low tensile elasticity and having a speci-
fic polar group, capable of bonding with the poly-
amide, wherein particles of the ionomer resin or
elastomer having a diameter of about 1 ~m or less
are dispersed in the polyamide (see, for example,
Japanese Patent Application Publication Specifica-
tion No. 55-44108/1980). Moreover, the known poly-
amide compositions include a polyamide composition
comprising a polyamide and, blended therewith, an
ionomer resin and a monoepoxy or carbonate compound
~see, for example, Japanese Patent Application
Publication Specification No. 53-44180/1978), and a
polyamide composition comprising a polyamide and,
blended therewith, an ionomer and an elastomeric
olefin copolymer (see, for example, Japanese Patent
Application Laid-Open Specification No. 58-
23850/1983).
All of the above-mentioned known polyamide
compositions, however, have a drawback in that
although shaped articles made therefrom exhibit
improved impact strength at their portions other
than the weld-line portions, they are not always
l3~7a67
good with respect to impact strength at their weld-
line portions and the average of the impact
strengths at their weld-line portions is low. Weld
lines are the lines or surfaces along which a poly-
mer must reunite and adhere to itself after flowing
around an interference during molding. In the manu-
facture of a shaped article from polyamide composi-
tions, the shaped articles, except those having an
extremely simple configuration, are generally caused
to have one or more weld-lines. If the shaped
articles are poor with respect to the impact
strength at their weld line portions, they have
difficulties in practical use.
Summarv Of The Invention
With a view toward developing a polyamide com-
position which is capable of providing shaped arti-
cles which are excellent ln Izod impact strength at
their weld-line portions as well as ln portions
other than the weld-line portions, the present
inventors have conducted extensive and intensive
studies. As a result, it has unexpectedly ~een
found that a polyamide composition comprising a
polyamide having a relative viscosity as high as
3.15 or more, an ethylene ionomer resin and a mono-
epoxy or carbonate compound can be easily molded
-- 4 --
i3~7~67
into various shaped articles such as automobile
parts, sporting goods and the like by injection
molding etc., which articles are excellent in Izod
impact strength at their weld-line portions as well
as at portions other than the weld-line portions, as
compared to conventional polyamide compositions. It
has also been found that the above polyamide compo-
sition can be further improved with respect to the
Izod impact strength at the weld-line portions of
shaped articles obtained therefrom by addition
thereto of an elastomeric olefin copolymer, an
elastomeric styrene copolymer and/or a polyvalent
alcohol. Based on these novel findings, the present
invention has been completed.
It is, therefore, an object of the present
invention to provide a novel high impact polyamide
composition which is useful for forming a shaped
article having excellent Izod impact strength at its
weld-line portions as well as portions other than
the weld-line portions.
The foregoing and other objects, features and
advantages of the present invention will be apparent
to those skilled in the art from the following
detailed de~cription and appended claims.
130~&7
Detailed_Description Of The Prese t Invention
According to the present invention, there is
provided a high impact polyamide composition com-
prising at least one polyamide (A)~ at least one
ethylene ionomer resin (B) and at least one mono-
epoxy or carbonate compound (C) of the formula (I)
Rl R3
X ~I)
wherein R1, R2, R3 and R4 each independently
repxesent a hydrogen atom or a lower alkyl
group, and X represents a divalent group of the
formula (II) or ~III) \/ l l
O , o O
lCI
(II) (III)
the welght proportion of the polyamide (A)
relative to the total of the components (A) and (B)
being 60 to 95 %, the weight proportion of the
ethylene ionomer resin (B) relative to the total of
the components (A) and (B) being 40 to 5 %, and the
weight proportion of the compound (C) relative to
the total of the components (A) and (B) being 0.05
to 5.0 %;
-- 6 --
13~7~7
the polyamide (A) having a relative viscosity
of at least 3.15 as measured at 25 C with respect
to a solution prepared by dissolving 1 g of the
polyamide in 100 ml of 98 % sulfuric acid.
Polyamides useful as the component (A~ of the
polyamide composition of the present invention are
linear high molecular weight compounds having amide
linkages. Representative examples of polyamides
- include homopolymers such as nylon 66, nylon 6,
nylon 610, nylon 612 and nylon 46, and copolymers
such as nylon 66 copolymers, e.g., nylon 66-6 and
nylon 66-610. These polyamides may be used alone or --
in combination. These homopolymers and copolymers
may be used in the form of a polymer blend such as a
polymer blend of homopolymers and a polymer blend of
a homopolymer and a copolymer. Representativë exam-
ple of polymer blends of homopolymers include a
polymer blend of nylon 66 and nylon 6 and a polymer
blend of nylon 66 and nylon 610. Representative
examples of polymer blends of a homopolymer and a
copolymer include a polymer blend of nylon 66 and a
nylon 66 copolymer and a polymer blend of nylon 66,
a nylon 66 copolymer and at least one of the other
nylons. Among the above-mentioned polyamides, nylon
66, a nylon 66 copolymer comprislng nylon 66 as a
. . .
13~ i7
major component, a polymer blend of nylon 66 and the
nylon 66 copolymer, and a polymer blend of nylon 66,
the nylon 66 copolymer and at least one of the other
nylons are most preferred from the standpoint of
heat resistance and mechanical properties.
According to the present invention, for attain-
ing Izod impact strength improvement at weld lines,
it is requisite that at least one polyamide to be
used as the component (A) of the present composition
have a relative viscosity of at least 3.15, prefer-
ably at least 3.45, as measured at 25 C with
respect to a solution prepared by dissolving 1 g of
the polyamide in 100 ml of 98 % sulfuric acid. In
the present invention, the relative viscosity is
measured in accordance with the method set forth in
Japanese Industrial Standard K6810. That is, the
relative viscosity of the polyamide is determined by
a ~ethod in whlch l g of a polyamide is dissolved
in l00 ml of 98 ~ sulfuric acid and the viscosity of
the resultant polyamide solution is measured at
25 C by means of an Ostwald viscometer. In the
present invention, the component (A) may be
comprised of a single polyamide having a relative
vi~cosity of at least 3.15. The component (A) may
also be comprised of a plurality of different poly-
1307~67
amides each having a relative viscosity of at least
3.15. Alternatively, the component (A) may also be
a blend of at least two polyamides having different
relative viscosities, provided that the relative
viscosity of the blend is at least 3.15. For
example, a polyamide having a relative viscosity of
less than 3.15 may be used in combination with a
~ different polyamide having a relative viscosity of
3.15 or more, for example more than 3.30, to thereby
form a polyamide blend for the component (A), pro-
vided that the polyamide blend has a relative visco-
sity of at least 3.15 as a whole.
By the use of at least one polyamide having a
relative viscosity of at least 3.15, preferably at
lea~t 3.45, an ethylene ionomer resin a~ will be
defined later can be homogeneously dispersed in the
polyamide matrix in the form of uniform particles
having a particle size as small as I ~m or less.
This homogeneous di~persion of the ethylene ionomer
resin ln the polyamide matrix enables the polyamide
composition to be formed into a shaped article
having improved weld-line impact strength. There is
no particular upper limit with respect to the rela-
tive viscosity of the component (A). However, the
relative viscosity of the polyamide is generally not
l307a~7
higher than about 5Ø A polyamide having a rela-
tive viscosity higher than 5.0 is not preferred from
the viewpoints of melt fluidity and economy.
As mentioned hereinbefore, a blend of poly-
amides having different relative viscosities may be
employed as the component (A) in the present inven-
tion. From the viewpoints of imparting excellent
melt fluidity to the polyamide composition and
obtaining a shaped article having excellent weld-
line Izod impact strength, it is preferred that the
polyamide blend be comprised of a polyamide having a
relative viscosity of at least 3.3 and a polyamide
having a relative viscosity of from 2.5 to 3.0, and
that the content of the former polyamide in the
polyamide blend be 70 % by weight or less. When the
content of the polyamide having a relative viscosity
o~ at least 3~3 in the polyamide blend exceeds 70 %
by welght, the polyamide composition tends to have a
poor melt fluidity.
The ethylene ionomer resin to be employed as
the component (B) of the high impact polyamide com-
position oi the present invention i9 a copolymer
comprising ethylene monomer units, ethylenically
unsaturated carboxylic acid monomer units, and
ethylenically unsaturated carboxylic acid metal salt
-- 10 --
13~ 7
monomer units. The copolymer may further comprise
ethylenically unsaturated carboxylic ester monomer
units. It is preferred that the molar proportion of
the ethylene monomer units relative to the total of
the monomer units contained in the copolymer be 90
to 98 %. The copolymer may be used alone or in
co~bination.
The above-mentioned ethylenically unsaturated
carboxylic acid monomer units are units derived from
an ethylenically unsaturated carboxylic acid contai-
ning 3 to 8 carbon atoms, such as acrylic acid,
methacrylic acid and ethacrylic acid.
The ethylenically unsaturated carboxylic acid
metal salt monomer units constituting part of the
ethylene ionom0r resin to be employed in the present
lnvention are units derived from a metal salt of an
ethylenically unsaturated carboxylic acid as
mentloned above. As suitable metals to be incor-
porated in the ethylenically unsaturated carboxylic
acid metal salt monomer units, there may be
mentioned, for example, metals of Groups IA, IB,
IIA, IIB and IIIA and fourth period metals of Group
VIII o the periodic table, such as Na, K, Cu, Mg,
Ca, Ba, Zn, Cd, Al, Fe, Co and Ni. Of these, Na, K,
Mg, Ca, Ba and Zn are preferred.
- 11 -
:
1~)7(~67
The ethylenically unsaturated carboxylic ester
monomer units constituting part of the ethylene
ionomer resin to be employed in the present inven-
tion are units from an alkyl ester of an ethyl-
enically unsaturated carboxylic acid containing 3 to
8 carbon atoms, such as acrylic acid, methacrylic
acid and ethacrylic acid. Representative examples
of suitable alkyl esters to be employed in the
present invention include methyl acrylate, ethyl
acrylate, n-butyl acrylate, tert-butyl acrylate,
isobutyl acrylate, methyl methacrylate, ethyl meth-
acrylate, n-propyl methacrylate, isopropyl meth-
acrylate, n-butyl methacrylate, tert-butyl meth-
acrylate and isobutyl methacrylate. Of these,
methyl acrylate, ethyl acrylate, methyl meth-
acrylate, isobutyl acrylate and n-butyl methacrylate
are preferred.
The ethylene ionomer resin to be employed in
the present invention may be produced according to
customary procedures. For example, the resin may be
produced by first copolymerizing ethylene with an
ethylenically unsaturated carboxylic ester according
to the known high-pressure ethylene polymerization
method, subsequently saponifying the resultant co-
polymer and finally subjecting the saponified co-
~3C~6~7
polymer to reaction for the formation of the metal
salt. Generally, it is difficult to produce a
copolymer of ethylene and an ethylenically
unsaturated carboxylic ester having an ethylene unit
molar proportion of less than 90 %r using a conven-
tional device for preparing a high-pressure poly-
ethylene. On the other hand, when the ethylene unit
molar ratio exceeds 98 %, the impact strength of the
ultimate shaped article will be insufficient.
With respect to the ethylene ionomer resin to
be employed in the present invention, it is
preferred that the number of moles of ethylenically
unsaturated carboxylic ester monomer units (a), the
number of moles of ethylenically unsaturated
lS carboxylic acid monomer units (~) and the number of
moles of ethylenically unsaturated carboxylic acid
metal salt monomer units (y) satisfy the inegual-
ities.
0~ 0.6, and
a + ~ + Y
0.1 < <0.9.
a + ~ + Y
In general, the greater the content of the
ethylenically unsaturated carboxyllc ester monomer
units in the ionomer resin, the greater the improve-
13~7(?67
ment in impact strength of the polyamide composi-
tion. This is especially true when nylon ~6 is used
as the component (A). However, when the content of
the ester monomer unlts is too large, especially
when the value of the formula
as defined above is more than 0.6, the
a + ~ + Y
physlcal properties, such as tensile strength, of
the polyamide composition are disadvantageously
deteriorated. With respect to the content of the
ethylenically unsaturated carboxylic acid salt
monomer units, when the content is too small, espe
cially when the value of the formula as
a + ~ + Y
defined above is less than 0.1, the fluidity of the
polyamide composition in its molten state is dis-
advantageously low. On the other hand, when the
content is large, especially when the value of
the formula is more than 0.9, the improve-
a + ~ + Y
ment in impact strength of the polyamide composition
is insufficient. It is required that the ethyleni-
cally unsaturated carboxylic acid monomer units be
present in the ethylene ionomer resin because these
units increase the affinity between the ethylene
ionomer resin and the polyamide in the polyamide
- 14 -
130'7067
composition of the present invention.
The ethylene ionomer resin to be employed in
the prasent invention may preferably have a melt
index of from 0.2 to 5 g/10 min as measured at a
cylinder temperature of 190 C under a load of
2160 g in accordance with ASTM D-1238. When the
melt index of the ethylene ionomer resin is less
than 0.2, the polyamide composition not only has
poor melt fluidity and impact strength but also
suffers silver streaking in the molding process
thereof. On the other band, when the melt index of
the ethylene ionomer resin is more than 5, the poly-
amide composition has a poor impact strength.
Moreover, the polyamide composition of the
present invention may contain at least one elasto-
meric copolymer (~) which is selected from the group
consisting of elastomeric olefin copolymers and
elastomeric styrene copolymers.
The elastomeric olefin copolymer may be a co-
polymer of ethylene and an alpha-olefin having at
least 3 carbon atoms, preferably 3 to 8 carbon
atoms. As specific examples of such a copolymer,
there may be mentloned, for example, poly(ethylene-
co-propylene), poly(ethylene-cobutene-1), poly(ethy-
lene-co-hexene-1), poly(ethylene-co-4-methylbutene-
~3~'71~
1) and poly(ethylene-co-4-methylpentene-1). These
may be used either alone or in mixture. Of these,
poly(ethylene-co-propylene) and poly(ethylene-co-
butene-1) are preferred.
In place of the above copolymer of ethylene and
an alpha-olefin having at least 3 carbon atoms,
there may be employed as the elastomeric olefin
copolymer a terpolymer of ethylene, an alpha-olefin
having at least 3 carbon atoms and an unconjugated
diene monomer. As the suitable diene monomer, there
may be mentioned, for example, methylene norbornene,
ethylidene-norbornene, 1,4-hexadiene and dicyclo-
pentadiene.
The molar proportion of each component of the
elastomeric olefin copolymer is not critical. How-
ever, it is preferred that the content of alpha-
olefin monomer unitc in the copolymer be 10 to 40 %
by mole, more preferably 15 to 35 % by mole, because
the glass transition temperature and the degree of
crystallinity of the elastomeric olefin copolymer
must be low to ensure a substantial improvement of
the impact ~trength at low temperatures of the
polyamide composition of the present invention.
On the other hand, as the elastomeric styrene
copolymer, there may be mentioned, for example, sty-
- 16 -
l~Q17~7
rene-butadiene rubber and a hydrogenated block
copolymer of styrene and butadiene.
The elastomeric olefin copolymer to be employed
in the present invention preferably has a melt index
of from 1 to 10 g/10 min as measured at a cylinder
temperature of 190 C under a load of 2160 g in
accordance with ASTM D-1238. ~hen the melt index of
the elastomeric olefin copolymer is less than 1, the
polyamide composition tends to not only have insuf-
ficient melt fluidity and impact strength but also
suffers silver streaking in the molding process
thereof. On the other hand, when the melt index of
the elastomeric olefin copolymer is more than 10,
the polyamide composition tends to have insufficient
impact strength. With respect to the elastomeric
styrene copolymer, it preferably has a melt index of
from 0.01 to 30 g/10 mln as measured at a cylinder
temperature of 230 C under a load of 2160 g in
accordance with ASTM D-1238. When the melt index of
the elastomeric styrene copolymer is less than 0.01,
the polyamide composition tends to not only have
insufficient melt fluidity and impact strength but
also suffers silver streaking in the molding process
thereof. On the other hand, when the melt index of
the elastomeric styrene copolymer is more than 30,
- 17 -
13~ 7
the polyamide composition tends to have insufficient
impact strength~
The elastomeric olefin copolymer or elastomeric
styrene copolymer in the polyamide composition
serves to improve the impact strength at low tem-
peratures of the composition. The weight proportion
of the ethylene ionomer resin to the elastomeric co-
polymer in the polyamide composition is generally
from 30 ~ to 95 %. When the amount of the elasto-
meric copolymer is too small, i.e., less than 5 %
relative to the amount of the ethylene ionomer
resin, incorporation of the elastomeric copolymer
in the polyamide composition does not lead to
desirable impact strength improvement at low temper-
atures. On the other hand, when the a~ount of the
elastomeric copolymer is too large, i.e., more than
70 % relative to the amount of the ethylene ionomer
resin, properties such as impact strength of the
polyamide composition tend to deteriorate.
In the polyamide composition of the present
invention, the weight proportion of the polyamide
(A) relative to the total of the components (A) and
(B) or the total of the components (A), (B) and (D)
is 60 to 95 %, and the weight proportion of the
ethylene ionomer resin (B) relative to the total of
13~'7~67
the components (A) and (B) or the weight proportion
of the total of the components (B) and (D) relative
to the total of the components (A), (B) and (D) is
40 to 5 %~
In the composition of the present invention,
there is incorporated as the component (C) at least
one monoepoxy or carbonate compound o~ the formula
(I)
Rl R3
X (I)
wherein R1, R2, R3, R4, and X are as defined above.
It is preferred that each of R1, R2, R3 and R4
have 1 to 3 carbon atoms.
Representative examples of monoepoxy compounds
Lnclude ethylene oxide, propylene oxide and butylene
oxide, and Representative examples of carbonate
compounds lnclude ethylene carbonate, propylene
carbonate and butylene carbonate.
The weight proportion of the compound (C) rela-
tive to the total of the components (A) and (B) or
the total of the components (A), (B) and (D) is in
the range of from 0.05 to 5.0 %~ preferably 0O5 to
3.0 ~.
- 19 -
i3(~
The monoepoxy compounds and carbonate compounds
are believed to chemically bind the polyamide with
the ethylene ionomer resin. Also, it is believed
that the monoepoxy compounds and carbonate compounds
form partial crosslinking between the polyamides and
between the ethylene ionomer resins. The above-
mentioned binding and crosslinking would stahilize
the morphology of the dispersed particles of the
ethylene ionomer resin in the polyamide composition,
thereby improving the Izod impact strength, partic-
ularly at the weld lines where complicated melt flow
of the polyamide composition occurs.
When the weight proportion of the component (C)
relative to the total of the components (A) and (B)
or the total of the components (A), (B) and (D) is
less than 0.05 %, the above-mentioned impact
strength improvement cannot be attained. On the
other hand, when the weight proportion of the com-
ponent (C) exceeds 5.0 %, excessive gelation occurs
during the melt kneading of the polyamide composi-
tion, thereby causing the production efficiency to
be lowered. Moreover, when the weight proportion of
the component (C) exceeds 5.0 %, a portion of the
component (C) remains unreacted and is left in the
ultimate shaped article. Further, the injection
- 20 -
~3Q~
molding o~ this composition produces a shaped
article having undesirable silver streaks on its
surface, which lower the commercial value of the
shaped article. The incorporation of the component
(C) in the polyamide composition in an amount
exceeding 5.0 % causes the impact strength of the
polyamide composition to be low.
With respect to the the polyamide composition
of the present invention, use of a polyvalent
alcohol having 2 to 20 carbon atoms as a component
(E) together with the above-mentioned component (C)
can further enhance the impact strength-improving
effect of the present invention. This polyvalent
alcohol acts as a dispersion medium for the mono-
epoxy compounds and carbonate compounds, and facili-
tates their dispersion in the polymer.
Suitable examples of polyvalent alcohols
include glycerin, ethylene glycol and pentaerythri-
tol. The polyvalent alcohol is preferably used in
the polyamide composition in a weight proportion of
10 to 100 % relative to the compound (C). When the
weight proportion is less than 10 %, the dispersion
of the compound (C) tends to be insufflcient. On
the other hand, use of the polyvalent alcohol in a
weight proportion of more than 100 % does not
13~
contribute to further improvement of the dispersion
o~ the compound (C).
In manufacturing the polyamide composition of
the present invention, it is necessary to simul-
taneously melt knead the components (A), (B), (C),
optionally together with the component (D) and/or
the component (E). Desired weld~line impact
strength improvement cannot be attained by melt
kneading in a manner where the components (A) and
(C~ are first melt kneaded and the resultant blend
is melt kneaded with the component (B). This fact
evidences that the component (C), i.e., monoepoxy or
carbonate compound, is involved in the binding
between the polyamide and the ethylene ionomer
resln.
The above-mentioned melt kneading may be con-
veniently conducted using a customary extruder. The
components of the polyamlde composltlon may be melt
kneaded at a temperature which is higher than the
~ melting temperature of the polyamide but lower than
the decomposltlon temperature of the polyamide.
For example, when the polyamlde is nylon 66,
the melt kneading temperature is generally in the
range of from 260 to 310 C. When the polyamide is
nylon 6, the melt kneadlng temperature is generally
13~7C1~7
in the range of from 230 to 310 C. The residence
time of the components in the extruder is generally
in the range o~ from 30 sec to ~ min. With respect
to the extruder apparatus, a twin screw extruder is
preferred to a single screw extruder.
When the component (D), i.e., at least one
elastomeric olefin copolymer and/or at least one
ela~tomeric styrene copolymer, is used in the
present invention, the component (D) may either be
simultaneously melt kneaded with the components (A),
(B) and (C), optionally with the component (E), or
first melt kneaded with the component (B) and sub-
seguently melt kneaded with the components (A) and
(C), optionally with the component (E).
For example, the polyamide composition accord-
lng to the present invention may be manufactured as
foLlows. Polyamide pellets, ethylene ionomer resin
pellets, elastomeric olefin or styrene copolymer
pellets, a monoepoxy or carbonate compound and a
polyvalent alcohol compound are blended together in
a tumbler blender or by a Henschel mixer. The
resultant blend is melt kneaded by means of a twin
screw extruder under conditions as mentioned herein-
before. In thls instance, there can be employed a
charge method in which only the polyamide pellets
13~7~
are supplied from the hopper of the extruder and the
other polymer pellets and compounds are fed from the
vent aperture of the extruder.
Additives of the types generally employed for a
polyamide composition may be added to the polyamide
composition of the present invention, if desired.
Examples of such additives are a lubricant such as a
stearic metal salt, ethylenebistearylamide and a
wax; a heat resisting agent such as a copper com-
pound, a metal halide and an organic heat stabili-
zer; a weather resisting agent such as a manganese
compound and carbon black; a reinforcing material
such as glass fibers, talc, kaolin, mica, wollasto-
nite and carbon fibers; and a colorant such as a
pigment and a dye. Other additives such as a heat
stabilizer and a weather resisting agent of the type
employed for an ethylene ionomer resin, an elastome-
ric olefin copolymer and an elastomeric styrene
copolymer may also be added to the polyamide com-
position of the present invention, if desired.
Any desired shaped articles such as automobile
parts, sporting goods and the like can be readily
produced from the the polyamide composition of the
present lnvention by means of, for example, an
in~ection molding machine. Shaped articles from the
- 24 -
~3g~ (,r~
polyamide composition of the present invention have
an excellent impact strength, as compared to that of
shaped articles made from conventional polyamide
compositions. In particular, with respect to a
S shaped article made from the polyamide composition
of the present invention, the Izod impact strength
variation from point to point is advantageously
small over the entire body of the article, especial-
ly between the non-weld-line portions and the weld-
line portion thereof. Also, with respect to a
shaped article made from the polyamide composition
of the present invention, the average Izod impact
strength over the entire body of the article is
advantageously high. Accordingly, shaped articles
lS made from the polyamide composition of the present
invention can advantageously be employed in various
applications where extremely high impact strength is
required. Thus, the polyamide composition of the
present invention can provide very strong automobile
parts and sporting goods.
Detailed DescriPtion Of Preferred Embodiments
The present inventlon will now be described in
more detail with reference to the following Examples
and Comparative Examples, which should not be
construed as limiting the scope of the present
- 25 -
13~
invention.
With respect to the following Examples and
Comparative Examples, the physical properties were
measured as follows.
(1) Weld-line Izod impact strength
Izod impact strength was measured at 23 C in
accordance with ASTM-D256, except that a strip-form
test specimen having a weld line perpendicular to
the lengthwise direction of the strip, which line is
in the middle of the length of the strip, was pre-
pared, and that a notch was made at one end of the
line. The test specimen was prepared by injection
molding a polyamide composition at a cylinder tem-
perature of 280 C using a metal mold having two
inlets and a strip-form cavity therebetween. The
polyamide composition was lnjected into the cavity
slmultaneously from both the inlets.
(2) Izod lmpact strength at low temperature
Izod impact strength was measured at 0 C in
accordance with ASTM-D256.
(3) Silver streaks
Strip-form test specimens were prepared by
in~ection molding a polyamide compositlon at a
cylinder temperature of 300 C. The surface of each
of the test specimens was observed by naked eye to
~ i3~;~u6 7
determine the occurrence of silver streaks.
(4) Melt fluidity
Using an injection molding machine having a
cylinder temperature of 280 C, a polyamide composi-
tion was injected into the cavity of a metal mold
maintained at a temperature of 80 C, which cavity
had been provided in the form of a spiral passage
having a width of 15 mm, a thickness of 2 mm and a
total length of 1340 mm. The polyamide composition
so injected flowed over a certain distance in the
cavity, and solidified. The distance from the
entrance of the cavity was measured as a parameter
for measuring the melt fluidity of the polyamide
composition.
(5) Diameter of ionomer resin or elastomer
component particles dispersed in the polyamide
composition
A test speclmen obtained by in~ection molding
at a cylinder temperature of 280 C was immersed in
liquid nitrogen for 1 hour and then cracked by
applying an impact thereto. Ionomer resin or
elastomer components present in the sur~ace portion
o~ the thus obtained section were extracted with
heated xylene, and then the resultant section was
observed using a scanning electron microscope (SEM)
- 27 -
13(~7(~i7
to determine the particle diameters. The extraction
of ionomer resin or elastomer components led to a
formation of holes in the section, which holes were
observa~le using the electron microscope.
The below-defined polymers were employed in the
following Examples and Comparative Examples, and the
meaning of each of the abbreviations employed is as
follows.
(Polymers)
Ethylene ionomer resin No. 1:
a copolymer comprising
94.5 mol% of ethylene monomer units,
2.0 mol% of acryllc acid monomer units,
2.2 mol% of zinc acrylate monomer units, and
1.3 mol% of isobutyl acrylate monomer uni-ts;
and
having a melt index of 1.0 g/10 min.
Ethylene ionomer resin No. 2:
a copolymer comprlslng
94.1 mol% of ethylene monomer units,
2.7 mol% of acrylic acid monomer units, and
3.2 mol% of zinc acrylate monomer units; and
havlng a melt index of 0.4 g/10 min.
Ethylene ionomer resin No. 3:
a copolymer comprising
- 28 -
13(~7~ ~
91 mol% of ethylene monomer units,
5 mol% of methacrylic acid monomer units, and
4 mol% of zinc methacrylate monomer units; and
having a melt index of 0.4 g/10 min.
Elastomeric olefin copolymer:
a copolymar comprising
90.4 mol% of ethylene mon~mer units, and
9.6 mol% of propylene monomer units; and
having a melt index of 4.5 g/10 min.
Elastomeric styrene copolymer:
Kraton G 1652 manufactured by Shell Chemical Co.
(Abbreviations)
EC: ethylene carbonate
PC: propylene carbonate
GL: glycerin
PE: pentaerythritol
Example 1
76 Parts by welght of a nylon 66 having a
relative vlsco~ity of 3.76, 24 parts by weight of
ethylene ionomer re~in No. 1 and 2.0 parts by weight
of ethylene carbonate were charged into a tumbler
blendsr and blended for 3 minutes, and then the
blend was kneaded at a cylinder temperature of
280 C at a qcrew revolution speed of 200 rpm and
extruded at an extrusion rate of 8 kg/hr by means of
- 29 -
13~'7(;~7
a twin-screw extruder PCM30(manufactured and sold by
Ikegai Corp., Japan) to obtain pellets. The thus
obtained pellets were subjected to the weld-line
Izod impact strength measurement. The result is
shown in Table 1.
Example 2
Substantially the same procedures as described
in Example 1 were repeated, except that a nylon 66
having a relative viscosity o~ 3.30 was used. The
result is shown in Table 1.
Comparative Example 1
Substantially the same procedures as described
in Example 1 were repeated, except that a nylon 66
having a relative viscosity of 2.86 was used. The
result is shown in Table 1.
Comparative Example 2
Substantially the same procedures as described
in Example 1 were repeated, except that ethylene
carbonate was not used. The result is shown in
Table 1.
As apparent from the results shown in Table 1,
in the case where the relative viscosity of the
nylon 66 used ls less than 3.15, and in the case
where neither a monoepoxy compound nor a carbonate
2S compound is used, the Izod impact strength of the
- 30 -
-- 13(~7~
polyamide composition is low.
Examples 3 to 5 and Comparative Example 3
Polymer blending, extrusion and pelletization
were conducted in substantially the same manner as
described in Example 1, except that a pelletized
nylon-66 having a relative viscosity of 2.86 and a
pelletized nylon-66 having a relative viscosity of
3.76 were employed in proportions as indicated in
Table 1. The resultant pellets of the polyamide
compositions were molded, and sub;ected to Izod
impact strength and melt fluidity measurements.
The melt fluidity of the polyamide compositions
of Examples 1 and 2 was also measured. The results
are show in Table 1.
The results of Examples 3 to 5 and Comparative
Example 3 demonstrate that with respect to polyamide
composltions in which a polyamide having a relative
viscosity of at lea~t 3.3 i5 employed in combination
with a polyamide having a relative viscosity within
the range of from 2.5 to 3.0, when the average
relative viscosity thereof is at least 3.15, the
polyamide compositions exhibit excellent Izod impact
strength at their weld lines.
As apparent from the results of Examples 1 and
3 to 5, a polyamide composition containing as the
- 31 -
13~7U ~7
component (A) a polyamide blend comprising a poly-
amide having a relative viscosity of at least 3.3
and a polyamide having a relative viscosity of from
2.5 to 3.0 in a weight proportion of 70/30 or less
has an Pxcellent fluidity.
Further, as apparent from a comparison of
Example 2 with Example 4, even if the relative
viscosities are the same, i.e., 3.30, the polyamide
composition containing as the component (A) a poly-
amide blend of a nylon 66 having a relative visco-
sity of 2.86 and a nylon 66 having a relative visco-
sity of 3.76 exhibits better melt fluidity and weld-
line impact strength than the polyamide composition
containing as the component (A) a single kind of a
lS polyamide, i.e., a nylon 66 having a relative visco-
sity of 3.30.
Example 6
70 Parts by welght of a nylon 66 having a rela-
tlve viscosity of 3.76, 22.5 parts by weight of
ethylene ionomer resin No. 1, 7.5 parts by weight of
ethylene propylene rubber ~EP) and 1.5 parts by
weight of ethylene carbonate were charged into a
tumbler blender and blended for 3 minutes, and then
the blend was melt kneaded and extruded by means of
a twin-screw extruder PCM30~manufactured and Rold by
- 32 -
1~'7~6~
Ikegai Corp., Japan) to obtain strands. The strands
were cooled in water and cut with a cutter to obtain
pellets. The thus obtained pellets were subjected
to weld-line Izod impact strength measurement and
Izod impact strength measurement at low temperature.
The results are shown in Table 1.
Example 7
Pellets were prepaxed in substantially the same
manner as in Example 6 except that Kraton G1652 (a
thermoplastic styrene elastomer manufactured and
sold by Shell Chemical Co., Ltd.) was used in place
of the ethylene propylene rubber. The obtained
pellets were sub~ected to weld-line Izod impact
strength measurement and Izod impact strength
measurement at low temperature. The results are
shown in Table 2.
Example 8
Polyamlde composition pellets were produced in
substantially the same manner as in Example 6,
except that there were employed 35 parts by weight
of a nylon 66 having a relative viscosity of 2.86
and 35 parts by weight of a nylon 66 having a rela-
tive viscosity of 3.76 instead of 70 parts by weight
of a nylon 66 having a relative vi~cosity of 3~76.
The results are shown in Table 2.
- 33 - ,,~
~'7~7
Example 9
Polyamide composition pellets were produced in
substantially the same manner as in Example 8,
except that Xraton G1652 as mentioned hereinbefore
was used in place of the ethylene propylene rubber.
The results are shown in Table 2.
Example 10
Substantially the same procedures as described
in Example 6 were xepeated, except that 30 parts by
weight of ethylene ionomer resin No.1 were used in
place of the ethylene propylene rubber, to thereby
obtain a polyamide composition. With respect to the
polyamide composition, Izod impact strength at 0 C
and Izod impact strength at the weld-line thereof
were measured in accordance with ASTM-D256. The
results are shown in Table 2.
From the Izod impact strengths of the composi-
tions at 0 C mea~ured in Examples 6, 7 and 10, it
is apparent that the incorporation of an elastomeric
olefin or styrene copolymer, namely an ethylene
propylene rubber or a Kraton, leads to an improve-
ment in high-impact properties.
As is apparent from the results in Examples 8
and 9, the composition in which an ethylene propy-
lene rubber or a Kraton is incorporated is excellent
- 34 -
~3C~'7~67
in high-impact properties at 0 C even in the case
where a combination of a polyamide having a relative
viscosity of 3.3 or more and another polyamide
having a relative viscosity of from 2.5 to 3.0 is
used.
Examples 11 to 14 and Comparative Examples 4 and 5
Ethylene carbonate was added to a mixture of 76
parts by weight of a nylon 66 having a relative
viscosity of 3.76, 18 parts by weight of ethylene
ionomer resin No. 1 and 6 parts by weight of an
ethylene propylene rubber in various amounts of from
0 to 8.0 parts by weight as shown in Tables 2 and 3.
In substantially the same manner as described in
Example 1, from each of the resulting mixtures,
polyamide composition pellets were prepared and
~ub~ected to weld-line Izod impact strength measure-
ment and silver streak observation. The results are
shown in Table~ 2 and 3.
As iq apparent from the results of Examples 11
to 14 and Comparative Examples 4 and 5, the composi-
tion containing no ethylene carbonate exhibited low
weld-line Izod impact strength. On the other hand,
with respect to the composltions each containing an
ethylene carbonate, the weld-line Izod impact
strength increased according to an increase in the
- 35 -
13~ 67
amount of ethylene carbonate added, but when the
amount of ethylene carbonate was as high as 8 parts
by weight, the weld-line Izod impact strength was
decreased and formation of a silver streak was
observed. Therefore, the polyamide composition
containing ethylene carbonate in an amount as high
as 8 parts by weight is disadvantageous in practical
use.
Examples 15 to 19
Glycerin was blended with a nylon 66, ethylene
ionomer resin No. 1, an ethylene propylene rubber
and ethylene carbonate in amount ratios as shown in
Table 3 as follows. First, 76 parts by weight of
nylon 66 having a relative viscosity of 3.76, 18
parts by weight of ethylene ionomer resin No. 1, 6
parts by weight of ethylene propylene rubber and 0
to 3 parts by weight of glycerin were charged into a
tumbler blender and blended for 3 minutes. Then, to
the resulting mixture was added 2.0 parts by weight
of ethylene carbonate and the mixture was blended
for 3 minutes. In substantially the same manner as
ln Example 1, polyamide composition pellets were
prepared from the mixture and sub~ected to weld-line
Izod impact strength measurement. The results are
shown in Table 3.
- ~3C~7(~'7
As is apparent from the results for Examples 15
to 19 in Table 1, the Izod impact strengths of the
polyamide composition in which glycerin is Lncorpo-
rated, as measured at the weld line of the composi-
tions, are high as compared with those of the co~po-
sitions in which glycerin is not incorporated, and
are increased with an increase in the amount of
glycerin incorporated, but when the ratio of the
amount of ethylene carbonate to that o~ glycerin is
decreased to less than 1:1, the above~mentioned
increase of the Izod impact strength of glycerin-
incorporated compositions does not result.
Example 20
Substantially the same procedures as those of
Example 16 were repeated, except that 38 parts by
weight of a nylon 66 having a relative viscosity of
2.86 and 38 parts by weight of a nylon 66 having a
relative vlscosity of 3.76 were used, to thereby
obtain polyamide composition pellets. The pellets
were sub~ected to the measurement of the weld-line
Izod impact strength. The fluidity at the time of
molding was measured with respect to the polyamide
compositions of Examples 17 and 20. The results are
shown in Table 1.
From the comparison of Example 20 with Example
- 13~7 a~
17, it is apparent that the polyamide composition
which contains a combination of a nylon 66 having a
relative viscosity of 2.86 and another nylon 66
having a relative viscosity of 3.76 and which has an
average relative viscosity of 3.30 is excellent both
in Izod impact strength as measured at the weld-line
of the composition and in fluidity at the time of
molding, as compared with the composition containing
a nylon 66 having a relative viscosity of 3.30
alone.
Example 21
35 parts by weight of nylon 66 having a rela-
tive viscosity of 2.86, 35 parts by weight of nylon
66 having a relative viscosity of 3.76, 22.5 parts
by weight of ethylene ionomer resin No. 3, 7.5 parts
by weight of ethylene propylene rubber and 0.25 part
by weight of glycerin were charged into a tumbler
blender and blended for 3 min to thereby obtain a
blend. Then, to the blend were added 0.5 part by
welght of ethylene carbonate and 0.2 part by weight
of 4,4'-butylidene-bis(3-methyl-6-tert-butyl phenol)
(Yoshinox BB, manufactured and sold by Yoshitomi
Pharmaceutical Industries, Ltd., Japan), and the
resulting mixture was blended for 3 min. The
resultlng blend was sub~ected to kneading and extru-
` ~3~ 7~ ~
sion in substantially the same manner as described
in Example 1, to thereby obtain polyamide composi-
tion pellets. The pellets were sub~ected to ~he
measurements of the weld~line Izod impact stren~th
and the Izod impact strength at 0 C. The results
are shown in Table 1. As is apparent from Table 1,
the composition is high both in weld-lLne Izod
impact strength and in Izod.impact strength at 0 C.
Examples 22 to 27 and Comparative Examples 6 and 7
Eight types of polyamide composition pellets
were separately prepared in substantially the same
manner as in Examples 16 to 20 e~cept that nvlon 6,
nylon 610, ethylene ionomer resin Nos. 1 and 2,
propylene carbonate and pentaerythritol were used as
components in various loadings as shown in Tables 3
and 4.
The thus obtained polyamide composition pellets
were sub~ected to the measurement of the weld line
Izod impact strength. The results are shown in
Tables 3 and 4. As i9 apparent from the results,
the polyamide compositions obtained in Examples 22
to 27, which have relative viscosities in the range
of 3.15 or more, are excellent in weld-line Izod
impact strength, while the compositions obtained ln
Comparative Examples 6 and 7, which have relative
- 39 -
~3~
viscosities in the range of less than 3.15 are poor
in weld-line impact strength.
- 40 -
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