Note: Descriptions are shown in the official language in which they were submitted.
~o~
FIELD OF THE IN~ENTION
Thls inventlon relates to polyamide composltionscontainlng reinforclng materials. More partlcularly, the in-
ventlon relates to compositlon~ Or polyamide resins contaln-
ing a mineral flller and an alkali metal titanate~
BACKGROUND OF THE INVENTION
It is known in the art to rein~orce polyamide re-
sins with varlous ~illers, for example, glass,asbestos,
wollastonite, silica, and the like. The filler ls ususlly
bonded to the polyamide through a silane coupling agent.
The flller is ordinarily chosen on the basis of
the end use propertle~ deslred in the rinal article molded
from the re~ln mixture. Fo~ some uses, such as automotlve
body parts, a resln ls needed that ls strong and tough, ~ree
o~ warpage, stl~, lmpact resi~tant and hlgh-temperature-
dlstortlon reslstant 9 and has good surface appearance.
Polyamlde reslns contalnlng a mlneral riller such as wollas-
tonlte, or sllica, have heat distortion temperatures that
are generally too low to be of use ln auto body parts.
Furthermore, in molded parts that contain notches mineral
rilled polyamide resins do not have as 800d strength as ls
desirable in many applications. On the other hand, polyamide
reslns contalning glass generally produce artlcles with a
high heat distortion temperature and at high glass loadings
(e.~., 30% by weight) acceptable notch toughness, but the
hlgh loading tends to degrade other properties such as sur-
face appearance and Gardner impact strength. Furthermore,
they tend to warp on sub~ection to high temperatures. Poly-
amides reinforced with wollastonite or slllca and glass
~ibers ofrer no advantage over glass relnforced polyamide.
-- 2 --
. ' ' ,,
~(~4~Z5
In fact, notch toughness is inrerior to glass relnforced
; polyamide.
The mineral-rllled polyamide reslns contalning an
alkall metal titanate that are provided by thls lnvention
; overcome the deficlencies mentioned above in glass fiber
contalning products and produce molded articles having hlgh
heat distortion temperatures and good strength properties
: (both tensile and notch toughness) and generally good lm-
pact strength. They also have better elongatlon propertles,
have an esthetically pleaslng surface appearance, and pro-
duce low warpage compared to polyamide reinforced wlth mix-
tures of mineral and glass fiber.
SUMMARY OF THR INVENTION
. ___ __
Thls invention provldes a polyamide composition com-
prlslng (1) 50-75% by wel~ht based on the wel~ht o~ the compo-
sltlon of at least one hlgh molecular welght polyamide, (2)
between about 20-48 . 5% by welght based on the welght of the
composltion of a particulate mineral filler comprising sllica
or a metalllc sillcate having a molsture content of less than
20 2% by weight of the flller and having at least 70% of its
j partlcles less than 10 mlcrons ln size and having an average
particle slze of between about 1-5 microns, (3) between
a~out 0.25 and 2% by welght based on the weight Or the mlner-
al flller of a silane coupling agent, and (4) between about
1 and 20~ by welght based on the welght of the composltion
of a fibrous alkall metal tltanate contalning less than 5%
water by welght of the titanate.
DESCRIPTION OF THE INVENTION
The polyamides useful in this inventlon are the
.
hlgh molecular weight polyamides normally employed in
.
-- 3 --
polyamlde reslns used to make molded artlcles. Thus the term
"high molecular weight polyamlde" iEl u~ed in the moldlng art,
and the polyamides employed ln the resln composition wlll
have a relatlve viscoslty Or between about 40 and 80 as
measured as de~crlbed ln ASTM D-789-72. Examples of 9uch
hlgh molecular welght polyamldes lnclude polyhexamethylene
adlpamlde, polycaprolactam, polydodecyl adlpamide, poly-`
tetramethylene adlpamlde, polyhexamethylene sebacamide, poly-
hexamethylene dodecamide, and copolymers such as caprolactam
and hexamethylene adlpamlde, as well as blends of the fore-
going, particularly a blend of polyhexamethylene adlpamide
and about 5-25% by weight Or polycaprolactam.
The particulate mineral flllers useful herein
lnclude slllca tcrystalllne or amorphous) or a metalllc
slllcate such as calclum slllcate or alumlnum sllicate.
The rlller should have a molsture (water)content of less
than about 2% by weight ln order to obtain the lmpro~ed
propertie~ of the articles molded from the reslns of thls
invention, and thus, ln some lnstances the filler should
be the calclned form. In addltlon, the properties of the
molded artlcle depend in part on the size of mineral filler
particles employed and it has been found that at least 75%
of the partlcles, by weight, should have a size less than 10
microns and that the average flller particle size should be
between about 1 and 5 microns. Preferably, at least 98% of
the particles by weight should have a slze less than 10
microns and the partlcles should have an average size less
than 1-3 microns. Further, in a preferred composition the
mineral filler will comprise between about 25% and about 35%
by weight.
The compositions require the presence of a silane
coupling agent to bond the mineral filler and the alkali
metal titanate to the polyamide. These are known coupling
agents and include amino-, epoxy-, and vinyl-containing
silanes such as 3-aminopropyltriethoxysilane, N-~ -(amino-
ethyl)- y-aminopropyltrimethoxysilane, and the like.
The alkali metal titanate fibers are single crys-
tals, and for use herein should contain less than 5~ water by
weight, preferably less than 1~ water. The preferred titanate
fiber is potassium titanate. The fibers should have a diameter
of between about 0.05-0.3 micron, preferably 0.1-0.2 micron;
and a length to diameter ratio of at least 15:1, preferably
at least 25:1, and most preferably between 30:1 and 50:1. The
alkali metal titanate fibers should be present in an amount
between about 1 and 20~ by welght based on the weight of the
composltion, preferably between 5 and 10~. The alkali metal
can be sodium, potassium, lithium, rubidium and the like.
The compositions of this invention may, of course,
contain conventional additives. These include mold lubricants
such as stearyl alcohol, metallic stearates, ethylene bis-
stearamide~ and the like; heat stabilizers such as copper
salts and alkali metal halides; and pigments.
Any of several methods ~or mixing the ingredients
of the resin composites are used so long as good dispersi-
bility is obtained. Ordinarily, the polyamide ingredient is
in the form of a molding powder, i.e., as granules or cubes,
although any form suitable as a feed to an extrusion appara-
tus is satisfactory. Preferably, the ingredients are melt
blended by feeding th~m into an extruder either individually,
premixed, or partly premixed, in any combination. For con-
venience, a twin-screw extruder is preferred.
t` '
': ' ':
~0~ '25
The composltions of thls inventlon can be inJected
under normal lnJectlon-molding pressure into molds for shap-
lng i~nto molded artlcles.
In the examples whlch rOllOw:
Tenslle strength and Elong,ation were measured as
described ln ASTM D-63~.
Flexural Modulus was measured as described ln
ASTM D-790. It i8 a measure of stirfness.
Heat Dlstortion Temperature is a test comblning the
effect of creep and flexural modulus versus temperature, mois-
ture content and thermal history. It wasmeasured as described
in ASTM D-648-72.
Izod Impact was measured as described in ASTM
D-256.
Gardner Impact was measured by usln~ a aardner
Laboratory Impact tester (model Ia-1125) using a sample holder
that had a 1.5 inch dlameter hole under the point of impact.
Thls openlng and the 0.25 lnch radlus tlp on the 4 pound dart
correspond to the speclflcations of Procedure B ln ASTM
D-3029-72~ The test specimen, a 5 x 3 x 1/8 inch plaque,
was placed over the hole, unclamped and the dart dropped from
a helght determined by the staircase method as ln Sectlon 11,
ASTM D-3029-72, varyln~ helght rather than welght. Data are
reported as average lmpact at break in foot-pounds/lnch,
correctlng for sample thickness.
Test specimens used to determine propertles were
stored, prlor to testlng in glass ~ars sealed with tape
untll tested dry-as-molded. All physlcal tests were on dry-
as-molded 1/8 lnch thick specimens except Heat Dlstortlon
3C Temperature, whlch was measured on 5 x 1/2 x 1/8 inch bars
annealed 0.5-hour ln 150C. silicone oll.
In the following exa~ples and comparison~, all
parts and pel~centages are in parts by weight unless other-
wise specified. The examples illustrate the compo~itions o~
the invention.
EXAMPLE 1
i A premix was made by surface coating 59.8~ poly-
hexamethylene adipamide (Zyte ~ 101) having a relative vis-
cosity of between about 43 and 52, with 0.2~ (0.5~ based
; on mineral filler) of 3-aminoprop~ltriethoxysilane. 35.0
of a mineral filler of wollastonite (calcium silicate, ob-
tained from Interpace Corporation as P-4 sollastonite) con-
taining less than 2~ water in which at least 70~ o~ the
mineral filler particles were less than 10 microns in size
and in which the particles had an average size between about
5 microns, and 5.0~ potassium titanate fibers (Fybe ~ D,
obtained ~rom the Du Pont Compan~) containing less than 1~ ~,
` water, were then added.
The premix was starve fed at about 25 pph (11.36
kg/hr) to a screw extruder (a Werner & Pfleiderer ZSK-28).
The extruder had a screw configuration and barrel tempera-
ture profile as follows:
-- 7 --
t-; -
~3~ ~t~
Temperature (C.) Screw Confi~ura ion
-
Rear 265-270 Type (No. o~ Elements)
Front 270-280 031-024/024
Die 275-280 031-045/045/125/2 Feed
031-045/045 R Transition
031-045~045
Other Data 031-030/060 (3)
Vacuum 30 in. (76.20 cm) 037-305/045 Kneading Block
Screw 175-225 rpm 061-030/010 Reverse
031-045/045 (2) Vacuum Port
031-045/045 (2)
031-030/030
031-024/048 (2)
Tlp ~ `
The pelletized product`was dried overnlght in a
70-80C. oven wlth about 20 lnch vacuUm, then molded into test
bar~ (5 x 0~5 x 1/8 inch) (12.7 x 1.27 x 0.32 cm) on a 3-ounce
Van Dorn reclprocatlng screw moldlng machine. Plaques (5 x 3
x 1/8 inch and 5 x 3 x 1/16 lnch) ~2.7 x 7.62 x 0.32 cm and
` 20 12.7 x 7.62 x 0.16 cm) were molded on a 6 ounce Van Dorn`re-
ciprocatln~ screw moldin~ machlne. Generally, the molding
conditlons were as follows:
_
-- 8 --
~: "
~ .- -. .. .. ~. - - .~ .
~rature (C.) 3-oz. Van Dorn 6~oz. Van Dorn
Rear 270 280
Center 275 280
Front 280 280
Nozzle 280 280
Melt 295 295
Mold 90 90
Cycle (sec.)
In~ectlon 15 or 20 15 or 20
Hold 25 or 20 25 or 20
Ram Fast Fast
Screw ~rpm) 60 60
Physical propertles were measured on drg-as-molded
test specimens and are tabulated in Table 1.
Comparison Te~ts
Compo~ltlons for comparl~on were prepared as in
Example 1. The compo~itions contalned ~he same polyamide,
mlneral flller, and sllane as uqed ln Example 1. The
compositlons are tested as rOllOws: :~
comParison B
Comparison A (Glass Containing~~
(Wollastonlte Composition) Composltlon)
59.8% polyamide 59.8% polyamide
0.2% 3-aminopropyl- 0.2% 3-amlnopropyl-
trlethoxysilane trlethoxysllane
40% P-4 Wollastonite 35% P-4 Wollasto~ite
5% glass fiber (OCF
K 828, 1/8 in.
chopped strand
3 rlber)
3~'~S
Comparl~on C
A thlrd comparlson compos:ition was prepared by
mlxing glass fibers (the same as used in Comparlson B) with
the same polyamlde used ln Example 1 until the mixture con-
talned 15~ glass by wei~ht and extrudlng the mixture through
a 2 lnch Sterllng slngle screw extruder having a rear tèm-
perature of 275-300C., a center temperature o~ 285C., a
rront temperature Or 280C., a die temperature of 270-285C.
and a melt temperature Or 290-305C. The vacuum was 27-28
inches; the screw velocity 40-50 rpm and the screw a 31:1
L/Dgeneral purpose design with gradual transition and vacuum
extension.
Plaques and bars were molded rrom these composi-
tlon as ln Example 1 and physical properties measured on
dry-as-molded test specimens. ~he propertles are tabulated
- in Table 1.
-- 10 --
: - : . . .. .. .
~, ~ ~,n~
D S
C~
l ~ ~- ~O O O
O ~
N -
H C:
~ ~ C~ O
U~ C~ CO ~ t-
~ 2~ O O O O
~d
04
`E;
H
,
0~
h~_
h ~ .
ON c~~ --I o ~ - .
h ~--oo ,~ ,~ N
o~
~ ~ ~o
h :~rla~
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,~ O ~:
C~
F~ ~ , ~ ' N
J 5
p~
O
_~ ~ ;
o~
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S: ~ 0 .o
o ~ ~ ala~ 0 ,D
~d~
u~ ~ ~ o~r o ~:o u, ~ o~
O ~l~rl ~O I ~ 0~ ~ ~o O ~
0 ~C ~) ~1 ~I ~ ~ a3 ~1 ~rl bD
O rJ ~ 0 ~h ~ ~I h ~ bO h
c~ p, ~ ~ ~1 ~ o ,~ ~d ~ ~ td ~
~t ~ O0~ 0 041r~ O~ o~ln
~C o ~o3 ~ :~3 o
C> C> V
.
-- ,11 --
1~ '3~i
As shown by the Table, the compositlon Or Example l
exhlblts better elongation and notched Izod values than
either comparison composit~ons ~ or C' and al~o better than
com~arl~on com~o~it1On U whlch is ~ resented herein to show
there ~ ~ n~ ~yner~1~tlc erfect u~nn c:omhininF the mlneral
riller and ~,la~s rlbers.
F,XAMPLE 2
The procedure of Example l was followed to prepare
two compositions of the following ingredients:
Com~ositlon l Com~osltion 2
69.85% polyamlde (the 59.8% polyamlde (the
polyamlde used polyamlde used
ln Example l) ln Example l)
20% of a mlneral 30% Or the silica
filler of sllica used ln compo-
partlcles con- sition l
tainlng less
than 2% water ln
; which at least
: 20 98% Or the par-
tlcles are less
than lO microns
in slze and have
; an average size
between about
-- 1-5 mlcrons
(Penna. Sand and
Glass Company -
Min-U-Sil~ lO)
0.15% 3-aminopropyl- 0.2~ 3-amlnopropyl-
triethoxysilane trlethoxysilane
- 10% of the fibrous 10% of the flbrous
- potasslum titan- potassium tltan-
ate used in ate used in
- Example l Example l
The mixture of each was extruded as in Example l,
and molded as in Rxample l. :
.
Comparison Tests
Comparlson ComPositlon A
A compositlon Or about 60% o~ the polyamlde used
above, 0.2g of the sllane used above and 40% Or the slllca
used above was prepared, extruded and molded as above.
Comparlson Composltlon B
A composltion Or about 60% Or the polyamlde used
above, 0.2% Or the sllane used above, 30% Or the sllica used
above and 10% Or the glass flber used ln Comparison Compo-
sion C Or Example 1 was prepared, extruded and molded asabove.
Comparlson Compositlon C
Glass-contalnlng composltion C o~ ~xample 1 was
used as Comparlson Composition C Or thl~ Example.
Properties are tabulated in Table 2.
~043~
~ ~ s ~s
C) ~ ., ,, ~
h O h O h h
O rl O O O O
h ~ E~ ~ Ei O O O
~ G v~
V~ ¢
S ~
h
C~ bO -
O O O ~ O
h ~ h ~1 ~ ~ a~
I
.
J~ S
1 o
h O 3 3 3 ,1 ,~
U~ ~
O Cq ~ P
~t
I ~a
t~ ~
.C r~ ~I c~l ~ o
Cl, C~ C~ ~ ~U O
~ zo ,~ ,~ ~ o o
o
h
h
O ~ ~ C~
J~ ~d o t~
N U~ h ~ `-- ~ ~Il~ a~ ~
~ ,~ N
~ a ~ E r'
m ~ Q
E~ E~ ~
h ~ ~ ~ ~o ~ o ~D
~ ~ tQ O L~
x ~ ~ ~ t
a~ ~o
o ~:
a~ o
J~
` ~1 1~ o~ N
~i ~1*.
~_,
O
~1 ~1
P
a) s
~ O O O O O ~'
rl bD-rl o O ~ o
q 0~ ~ ~ ~1
, ~n 3 t~
E~ ~ ~ ~ ~ ~t
U~
~I N
r~ ~ ~ ~ m c)
O O O ~d ~
., ~ o ~ ~ o ~ ~q ~ o ~q
O ~ ~1 0 ~ ~ td O ~ ~d .
o a1 o a~ o ~ ~ tn ~ ~ ~ bO h ~ ~ ~ h
P --I ~ ~1 ~ h u~ h u~ o h D
~ ~ ~e ~ o~ ~d o~ ~ o~S,
o ~ o ~ O 0~ ~0 ~0 0
X X O O O O O O
C)C~ C)V C~C) -
-- 14 _
.
3~3~
As shown in Table 2, the composltlons of thls ln-
ventlon have better notched Izod values and better surface
appearance than any other comparison composltlons ln Example
2. They also have better Heat Dlstortlon Temperatures than
Comparison Composltion A and better elongation than Comparison
Composltlons B and C.
EXAMPLE 3
The procedure of Example l was followed to prepare,
extrude and mold the followlng composltions:
- lO A. 49.8% of the polyamlde used ln
Example l
10% of polycaprolactam havlng
a relatlve viscoslty between
41 and 52 (Pla~kon~ 8200 -
Allied Chemlcal Company)
30~ of the sillca mlneral flller
u8ed ln Example 2
0.2% 3-amlnopropyltrlethoxysllane
10% of the flbrous potasslum titanate
used ln Example l
B. 59.8~ polyamlde (same as ~sed ln
Example l)
30% slllca (used in Example 2)
0.2% 3-aminopropyltriethoxysilane
10% fibrous potasslum titanate
contalnlng less than 5% water
(Fybex~ L)
C. 49.8% of the polyamlde o~ Example 3A
10% of the polycaprolactam of Example
3A
0.2~ 3-aminopropyltriethoxysilane
10~ of the fibrous potassium titanate
used in Example 3B
30% of the silica mineral filler material
of Example 3A
D. 49.8~ of the polyamide of Example 3A
10% of the polycaprolactam of Example
3A
; 30% of the ~ollastonite mineral filler
. 10 used in Example 1
0.2~ 3-aminopropyltriethoxysilane
10~ of the fibrous potassium titanate
used in Example 3C.
PropertLe~ ere tebuleted in Teble 3.
,
.
'
- 16 -
- ` `:
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t~ h O h O O O
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.q ~
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t~ ~ S ~ ~O ~oo~
L~ C~ ~ N O N0~
H O ~I H ~10
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o
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v~ h ~>`-- ~ co
~ a ~ ,~
tr~ h :~ ~Q
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a
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- h ~rl ~1 ~0 ~O
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C~
-- 17 --
~0~3~3ZS
The preceding representative examples may be varled
wlthln the scope of the disclosure hereln, as understood and
~racticed by one skilled ln the art, to achleve substantlally
the same results.
The fore~oi.n~ det,a~léd descrl~tion has been F~lven
for clearness Or understandin~ only and no unnecessary llml-
tations are to be understood therefrom. The lnventlon ls not
llmited to the exact details shown and descrlbed ror obvious
modlfications will occur to those skllled ln the art~
- 18 -
.. . . .
.: - . . , : . . .
