Note: Descriptions are shown in the official language in which they were submitted.
p~
This invention relates to an impro~ed molding
material structure of a thermoplastic resin composition
which is capable of producing molded articles in which
glass fibers are dispersed uniformly in the resin matrix
with longer average fiber length to improve various
properties of molded articlesg said structure being
also improved in processing characteristics and free
from such problems as damaging molding machines through
frictional abrasion with the glass fibers contained therein.
Molded articles of glass flber reinforced thermo-
p:Lastic resins have been used as useful moldin~ materials
having excellent physical properties, especla].ly
mechanical strength, as well as excellent moldability
inherent in thermoplastic resins. Since oil shock in
19739 they have further arrested attention as utili-
zation of the material with higher added value and
improvement of their physlcal properties has been keenly
longed for. In prior art9 these molded articles have
been prepared especially by injection molding f`rom
various molding materials. Among them, typical
commercially available injection molding material for
glass iber reinforced thermoplastic products is
constituted of chopped strands of a glass fiber dispersed
in a thermoplastic resin9 which is prepared by extrusion
of a thermoplastic resin together with glass fibers.
Alternatively, another type of molding material havlng
glass fiber core enclosed within a thermoplastic resin
as outer coating or shell is also known in the art9 as
disclosed by U.S. Patent 29877~501 and U.S. Patent
3,608~033. The molding material of the former type,
-- 2 --
8~
while it is advantageous in simple and easy preparation
procedure 7 it is entirely impossible to have mono-
filaments with longer lengths dispersed uniformly
throughout the resin. Thus~ this type of molding
material can enjoy only limited reinforcing effect with
glass fibers inherent within such a structure. On the
other hand, in the latter type of molding materia].g the
glass fibers are present as core in the central portion
of the material covered with a uni-layer coating of a
thermoplastic resin. Consequently, the glass fibers
fail to be uniforml,y dispersed in the resin when
fabrlcated into a molded article. ~urthermore, with
such a uni-layer coverage of ~glass fibers~ the molding
material cannot be free from the problem of damaging
mechanical parts at the time of molding because glass
fibers exposed by disintegration of outer shell are
directly contacted with such mechanical parts.
It is an object of the present invention to
provide a molding material of Klass fiber reinforced
thermoplastic resin which will not cause damaging of
molding machines through frictional abrasion and can
be molded into an article in which glass fibers with
longer length are dispersed uniformly to improve
reinforcing characteristics of the thermoplastic resin.
Another object of the present invention is to
provide a process for producing a molding material of
glass fiber reinforced thermoplastic resin as mentioned
above by a simple and safe as well as economical
procedure.
Still another object of the present invention
8~L~
is to prov.ide a molded ar-ticle of glass fiber reinforced
thermoplastic resin improved in physical properties,
especially mechanical streng-th.
According to the present invention, there is
provided a molding material structure w:hich comprises (1) at
least one inner pillar-shaped body, each comprising a bundle
of glass fiber filaments and a non-orien-ted thermoplastic
resin, the glass fiber being respectively separated Erom each
other and extending in parallel to each other through the
said non-oriented resin and (2) an outer cove.ring layer of
an oriented thermop:l.asti.c res:i.n which is suhstant:ia:l.:Ly
oriented in the axial direction of the glass fiber filaments
and compatible with the non-oriented thermoplastic resin in
the inner pillar-shaped body wherein glass fiber content in
the composition is from 5 .to 60 % by weight, the proportion
oE the thermoplastic resin in the inner body from 0.25 to 18 %
by weight and that in the outer layer from 9~.75 to 22 % by
weight, each being based on the total composition arl~ the
~o
length of the structure is from 1~~ mm.
The improved molding material structure o:E the
present invention may be bet-ter understood with reference
to the acccompanying drawings, in which:
Fig. 1 shows cross-sectional view in the vertical
direction of one embodiment of the present invention
shaped in right cyl.indrical pellet, in whi.ch there are
five inner bodies of a thermoplastic resin containing
glass fiber filaments embedded in an outer covering
layer of thermoplas-tic resin;
dm~
L7
Fig. 2 perspective, partially exploded view of
the right cylindrical pellet, of which vertical cross-
sectional view is shown in Fig. 1, taken along the line
A-A in Fig. 1, showing only the ou-ter covering resin
layer portion from which the inner resin bodies containing
glass fiber filaments are plucked out;
""~ ~ ,
,J~'
(1rn ~
Fig. 3 perspective view of the lnner resin
body plucked out from the right cylindrical pellet as
shown in Flgs. l and 2j
Fig. 4 schematic illustrat;ions of the structures
of prior art9 indicating the states of fracture thereof;
Figo 5 a flow sheet a illustrative schematically
of the steps of the process for preparation of the molding
material structure of the present inventionj and
Fig 6 a longitudinal cross-sectional view of
one example of a die to be used for preparation of the
molding material structure of the present invention.
~ s shown in ~ . 1, at least one inner res:ln
body 2 containlng a large number of mono-filaments 3 are
embedded in outer covering resin layer l. In one aspect~
the inner thermoplastic resin body in the present molding
material structure is required to be non-oriented~ while
the outer covering thermoplastic resin layer substantially
oriented. The terms "non-oriented" and "substantially
oriented" herein used mean whether there is substantial
shrinkage of the resin in a certain direction when
measured under conditions as hereinafter specified.
The inner thermoplastic resin body 2 of the
present structure contains a large number of mono-
filaments which extend in parallel to each other through
2~ the resin body in the longitudinal direction thereof7
as shown in ~i~. 3. The resin in the inner body has an
interseptal function for separating the filaments from
each other so that the resultant molded article may
contain uniformly dispersed glass fibers with longer
lengthO Such a structure of the inner body is critical~
because glass fibers which are not well separated from
each other but contained as a bundle of filaments in the
molding material will fail to be un~formly dispersed in
the resultant molded article. The filaments 3 ln the
inner body 2 may be derived conveniently from commercially
available glass fiber rovings. Such glass fiber rovings
generally consist of from 500 to 20000 end filaments
with diameters from ~ to 20 microns. These glass rovings
are usually treated with so called sizing compound,
typically silicon type coupling agents, during manu-
facturing steps of glass fibers. Most of the presently
avallable ~lass ~iber rovlngs conta:ln about l wt.% of
such a coupling agent, lubricant or sheafing agent.
The shape of the inner body is not specifically limited
insofar as such a large number of filaments of glass fiber
can extend through the resin matrix separately in
parallel to each other. While its vertical cross--
section is generally ellipsoidal or spherical, it
may also be otherwise such as triangular, rectangular
or multangular. The number of such inner bodies may be
variable from l to 40 or even higher, preferably from
1 to 10 depending on various conditions in the intended
uses or preparation methods, but it is most preferably
from l to 5.
~5 mentioned aboveg the outer covering resin
layer l of the present molding material structure is
required to be substantially oriented in the axial
direction of the glass fiber filaments contained in the
inner resin body as described aboveO One of the
advantage of the molding material structure of the present
-- 6 ~
invention resides in that it causes little damage of
mechanical parts during molding operations. While being
not bound by any theory, it is believed that such an
effect is due to the specific structure of the in~ention.
To speak of injection molding9 pellets of a molding
material are not still molten in the zone extending from
feed zone to compression zone of a screw in an injection
or extrusion moldin~ machine but there occurs me:Lting of
pellets simultaneously with fracture thereof. ~rictional
abrasion of metals such as screw or barrel is considered
ko be due to the friction with glass flber before the
resin containing ~,lass fiber is molten. ~or example9
in case of the blended glass fiber composition of prior
artg abrasion in the region from feed zone to compression
zone is so great that after a month's operation the
in~ection molding machine may sometimes fail to give
favorable molded articles. In other words, at meltingg
kneading and measuring portions of the screw wherein
the thermoplastic resin is sufFiciently molten to exhibit
excellent lubricating effect, there occurs substantially
no abrasion of screw or barrel. The specific structure
of the present invention serves to earlier melting of
local sections of the thermoplastic resin around the
glass fiber. Namely9 the outer covering resin layer
which is oriented in the axial direction of glass fiber
is liable to be readily broken in the oriented direction
(longitudinal fracture~ through shearing force in the
feed zone and compression zone of the screw. As the
result of such longitudinal fracture of the outer
covering resin~ the molding material is separated into
the mass of khe oriented outer layer and the inner
body containing glass fiber filaments enclosed within
non-oriented thin layer resin (see Fig. 2 and Fig. 3).
Thusg the inner resin body containing glass fiber
filaments is removed from the outer covering resin
layer and therefore the thin resin portion around the
glass fiber is directly heatedg without intermedi.ary
poorly thermoconductive resin layerg in the screw to
be readily moltenO In contrastg as shown in Fig. L~(a)g
when the glass fiber is enclosed within only one non-
oriented resin structure, it takes a long time before
whole of a thick resin portion around the fiber is
molten and therefore the machine suffers from
frictional abrasion of screw or barrel1 furthermoreg
the fibers are also broken together with the resing
failing to give molded articles containing glass
fibers with long average lengthO On the other hand,
as shown in Fig. 4~b)g when a bundle of glass fiber
filaments is enclosed only within an oriented resin,
the glass fibers are exposed as the result of longitudinal
fracture of the oriented resin in the screw to be
directly contacted with metals to cause friction.
In the molding material structure according to
the present inventiong the glass fiber content in the
inner thermoplastic resin body is from 5 to 60 % by
weight based on the total compositiong the proportion
of the non-oriented resin in the inner body from 0.25
to 18 % by weight and the proportion of the orienked
resin in the outer covering resin layer from 94O75 to
22 % by weight~ each being based on the total composition.
- 8 -
~8E~7
In the present inventiong the thermoplastic resin
to be used for the oriented outer covering resin layer is
required to be compatible with the thermoplastic resin to
be used for the non-oriented resin body. The word
"compatible" herein mentioned means that one resin contains
common monomeric units contained in another resin or that
there occurs no inter-layer peel-off between one resin and
another. The compatibility of typical combinations of the
thermoplastic resins for use in the inner layer and outer
layerg respectively, are set forth in the following
Table 1:
_able 1
. _ __ ___ __ _ __ __ ___ __
PS AS ABS PPl~, PE PP POM PC PA PMMA PVC Ionomer
'PS---'''-'~- C __ _. __ __ _ __ _ _~ _.
AS N C _ _ _ _ _ _ _ _ _ _
_ _ _ _ _ .................... __I
ABS N C C _ _ _ _
PPE C N N C _ _ _
PE N N N N C _ _ _ _ _
PP N N N N C C _ _
POM N N N N N N C
. _ _ _ _ I . _ _
PC N C C C N N N C
. . _ __ . __
PA N N N N N N N N C _
PMMA N C C N N N N L N C ¦ _
PVC N N C N N N N N C C
_ _
Ionomer N N N N C C L N C N N C
(note) C=compatibleg L=limitedly compatible, N=non-
compatible~ PS=polystyrene(including high-impact poly-
styrene)~ AS=acrylonitrile-styrene copolymer; ABS=acrylo-
nitrile-butadiene-styrene copolymer(including methyl
methacrylate-butadiene-styrene~ methyl methacrylate-
acrylonitrile-butadiene styrene and acrylonitrile-
butadiene-a-methyl-styrene-styrene copolymers) 3 PPE=
polyphenylene ether(including modified PPE)~ PE=poly-
ethylene; PP-polypropylene; POM=polyoxymethy:Lene J PC=
polycarbonate; PA=polyamide; PMMA=polymethyl methacrylate
PVC=polyvinyl chloride
g
.7
The degree of orientation of the outer covering
thermoplastic resin layer can easily be judged and tested
by compression breaking of the molding material by means
of, for example, pincers with muscular strengthg etc. to
effect longitudinal fracture thereof. By such a test
method, the state of fracture in cylinders of a molding
machine as mentioned above can easily be visualized.
More quantitatively, howeverg the substantial orientation
required for the outer thermoplastic resin layer is
defined as having at least 0.5 % therma] shrinkage in
the axial direction which is observed when the oriented
resin, from which the non-oriented glass fiber containing
inner layer has been removed, :Ls exposed to heat at a
temperature higher by about Ll5C than the ~icat softening
point (~STM-D-1525) of the oriented resin for 30 minutes.
Such a degree of orientation can readily be imparted to
the resin by extruding a molten resin through an
extruder, followed by cooling.
The non-oriented thermoplastic resin in the
inner body as described above can generally be derived
from an emulsion of a thermoplastic resin. In order to
permeate through mono-filaments of glass fiber roving,
such an emulsion is required to have affinity with glass
fiber and a low viscosity of 100 centi-poise or less.
~or this purpose9 it is preferred to use an aqueous
emulsion having small particles of a thermoplastic resin
dispersed in waterO When glass fiber roving is immersed
in such an aqueous emulsion and dried, small particles
of the resin are adhered around each mono-filament of
the glass fiber. Such small particles of a thermoplastic
-- 10 -
resin will form, even when molten at a high temperature
to be fused with each other~ a substantially non-orîented
resin matrix.
The resin component in the non-oriented resin
matrix is preferred to have a melt flow property (which
depends primarily on molecular weight within the same
kind of resins) which is the same as or superior to
(i.e. smaller in molecular weight than) that of the
thermoplastic resin for the outer layer, so that
dispersion of glass fibers in injection molded products
obtained from the resultant molding material may be good
to improve physical properties~ e.g. Izod impact strength,
by about 10 to 20 %.
The molding material structure of the present
invention is not particularly limited in its shape but
inclusive of all shapes and sizes known in the art as
pellets. Preferably9 however, it is shaped in cylinders
with spherical or ellipsoidal cross-sections vertical to
the axial direction of the glass fibers contained
therein with shorter diameters ranging from l mm to 8 mm
and lon~er diameters ~an!~ing!~rom 1 m~ to 15 mm~ the 1ength
of tk~cyl~n~e~s bqing preferably ~`r~rn l ~ to 2~ mm~l If
desired, other shapes including cylinders with tri-
angular, rectangular, multangular cross-sections may
also be employed.
There may be employed various methods for
preparation of the molding material structure of the
present invention as described above. Referring now
to a preferred embodiment of the process according to
the present invention as illustrated in Fig. 5 and 6~
38~L7
the process ~or preparation of the present molding
material structure is described in detail belowO The
process of the present invention comprises first treating
at least one g].ass fiber roving comprising from 500 to
20000 end filaments with an aqueous emulsion of a
thermoplastic resin to disperse each filament uniformly
in said emulsion, followed by drying, to form an inner
thermoplastic resin body containing the glass fiber mono-
filaments extending therethrough in parallel to each other
separated by the thus formed non-orientedg thin inter-
septal resin and then applying extrusiorl coating on the
thus formed inner layer of another thermoplastic r-esin
which is compatlble with said thermoplastic resin ~or
inner body to form an outer covering layer oriented in
the direction of extrusion on said non-oriented inner
resin body, and pelletizing the glass fiber roving
enclosed within double structured layers into suitable
size of pellets.
One of the specific features of the process
according to the present invention resides in pre-
treatment of glass fiber roving wlth an emulsion of a
thermoplastic resin which is compatible with the thermo-
plastic resin to be used for extrusion coating. As
mentioned above~ commercially available glass fiber
roving generally employs a bundle of about 2,000 filamentsg
each filament being in the order of about 10 micron3 in
diameter. It is almost impossible in principle to coat
each element of the filaments by extrusion coating of
a highly viscous molten resin which is incompatible with
glass fibers. By treating a glass fiber roving ~hich
- 12 -
is hydrophilic in nature previously with an aqueous resin
emulsion which is low in viscosity9 each of the glass
fiber ~ilaments can be coated with said resin, thereby
improving protection of the glass fibers as well as
dispersibility(diffusion) of the glass fibers in the
thermoplastic resin.
As shown in ~igo 5, glass fiber roving 4 is
led into pre-treatment liquid bath 5 to be immersed
therein. The pre-treatment liquid bath 5 is provided
for coating an aqueous emulsion of a resin which is of
the same kind as or compatible with the thermoplastic
resin 13 supplied from the extruder 7. The aqueous resin
emulsion is permitted to permeate into the glass fiber
roving Ll while it is immersed in and passed through said
liquid bath to thereby coating each element of glass fiber
mono-filaments with the aqueous resin emulsion to be
adhered thereon.
Immersion of the glass f'iber roving in said
resin emulsion may simply be conducted by passing -through
said resin emulsion which is contained in a conventional
liquld bath. Alternatively, a vibrator such as ultra-
sonic vibrator is provided in said emulsion liquid bath
so as to vibrate the emulsion~ whereby the immersion
effect(coating adhesion effect) can be complete and
production speed can also be accelerated.
The amount o~ the emulsion to be adhered by
coating in the pre-treatment bath may be from 5 to 30
parts by weight as calculated as the resi,n content
adhered after drying said emulsion9 preferably ]5 to 25
3 parts by weight9 per 100 parts by weight of the emulsion
- 13 -
coated glass fiber roving after drying. With an amount
of less than 5 parts by weight~ the glass fibers cannot
completely be dispersed in the thermoplastic resin~
whileg an amount in excess of 30 parts by weight is
difficult to be coated uniformly by once-thru immersion.
~or coating such a large amount of resin~ adhesion by
way of several times repeated coating or any other
specific device is required. For the purpose of the
present invention9 no such specific concern is necessary.
The solid component(mainly resin component) in
said resin emulsion may be within the range from 30 to
70 % by weight as is conta:Lned in conventional commer-
cially available emulsions~ thus requiring no specl~lc
emulsion to be used.
The emulsion coated on the glass fiber roving
4 in the pre-treatment bath 5 is dried by a heater 6.
The heater 6 may be any of those utilizing radiant heat
such as nichrome wire heater~ etc or those utilizing
heated air. Especiallya when drying ls conducted by
use of a far infrared ray heater~ utilization efficiency
of electricity is good. I'he lnternal atmosphere
temperature in the heater 6 through whlch the glass
fiber roving 4 is passed may sufficiently be about 100
to 350C. In case of some latices which are not good in
heat-resistance and may cause irregularity through
thermal shrinkage at higher temperatures such as SB latex,
it is desired to effect drying at 100 to 150C.
The extruder may be any of conventionally
used extruders for thermoplastic resins~ so long as
it can feed stably a plastified molten resin without
- 14 -
output irregularity to a die 8. The extrusion die ~ is
provided for the purpose of extrusion coating of the glass
fiber roving. It may be a die frequently used f'or wire
coating9 etc. But, when five bundles of glass fiber
roving are to be included within one pellet, for
exampleg it is preferred to introduce five bundles of`
the emulsion treated glass fiber roving as described
above individually one by one into said die. Further-
more, it is also preferred to have a die structure which
enables another coating9 namely twice~double) coating~
of the five bundles by such a method as sheafing the
five bundles at one spot in the die. Double extrusion
coating is preferable because g,lass fiber rovings~ which
usually consist of a bundle of 500 to 20000 ends of very
fine filaments as mentioned above, are liable to be
loosened to permit filaments exposed on the surface of
the extrusion coated strand(linear body) if only one
coating is applied. The glass fibers exposed on the
surface may be separated in the subsequent pelletizing
step from the resin due to :Lnsufficient adhesion to the
resT,n~ resulting in unfavorable scattering of such
separated glass fibers.
The die structure~ which may differ depending
on production speed~ is preferably such that the internal
pressure in the resin may be increased and the pressure
beared 'by the resin extruded may actuate in the direction
of alleviating the drawing force imposed on said coated
strandO ~?ig. 6 shows one example of the extrusion
coating die for double coating.
- 15 -
The
The heater 6 and the die 8 should prererably
be disposed such that the glass fiber roving dried and
heated in the heater 6 may smoothly be introduced into
the die 8 without abrupt flection and withou-t too much
cooling. For~ if a ~lass fiber roving having 5 % or- more
of the emulsion adhered, which is considerably rigid,
is abruptly flexed, there is a fear that it may be
broken to cause entanglement thereof` at the inlet portion
of the die.
The strand having glass fiber cores coated with
a thermoplastic resin by the extrusion coatin~ die ~ to a
desired glass fiber- content is cooled in a cooling water
bath 9 to be solidified and wound up by a roll 10. Said
strand is pelletized by a pelletizer (cutting machine) 11
to a desired strength. Said pellets are stocked up in a
hopper 12 to be provided for use as molding material.
The glass fiber content in the final glass fiber
reinforced thermoplastic resin molding material is prefer-
ably from 5 to 60 % by weight. With a content less than
5 % by weight~ there is no remarkable effect of reinforce-
ment with glass fibers. On the other hand, a content
exceeding 60 % by weight will make molding of the material
difficult. The amount of the resin to be coated by emul-
sion treatment is from 0.25 to 18 % by weight, while that
by extrusion coating from 94.75 to 22 % by weight.
The thermoplastic resin to be used for the aqueous
emulsion in the ~irst step and that for the extrusion c02t-
ing may be of the same kind or compatible with each other.
These thermoplastic resins are generally selected from
those as mentioned in Table 1. Preferable classes of
16 -
.
. ~ ~
combinations of these resins to be widely used in
commercial application are set forth in Table ~ below.
Table 2
Oriented resin (formed Non-oriented resin (formed
Class by extrusion coating? from aqueous emulsion)
1 Polystyrene(including Polystyrene resin or
rubber-modified high- Styrene-butadiene resin
impact polystyrene)
2 Acrylonitrile-styrene Acrylonitrile-styrene
resin resin, or a copolymer of
styrene with at least one
monomer selected from the
group consisting of
acrylonitrile, acrylic
acid(derivative) and
methacrylic acid
(derivative)
3 Acrylonitrile-butadiene- 1'he same resin as in
styrene resin; Methyl Class 29 or a resin of
methacrylate-acrylo- the same kincl as the
nitrile-styrene- oriented resin
butadiene resin9 Methyl
methacrylate-styrene-
butadiene resinl or
Acrylonitrile-butadiene-
~-methyl styrene-
styrene ~esin
Ll Polyphenylene ether Polyphenylene etherg
or modified poly- modified polyphenylene
phenylene ether ether or polystyrene
resin
Polyethylene or Polyethyleneg poly-
polypropylene propyleneg ethylene-
vinyl acetate copolymer
or ethylene-methacrylic
acid copolymer resin
The thermoplastic resins as mentioned above to
be used in the present invention have generally the
melt-flow rates as shown in Table 3 belowg which are
measured by ISO R1133~1969 "Determination of the Melt
~low Rate of Thermoplastics" or a method similar thereto
under conditions as given in the same Table.
- 17 -
Table 3
MFR measurement The range
Thermoplastic conditions (tem- of MFR
resin v~lue Remarks
Polystyrene 200C9 5 ~g 1 100 Rubber
~procedure ~) modified
po ly~
styrene
being
included
: Acrylonitrile- 220~g 10 kg 1 - 100 Acrylo-
styrene nitrile/
styrene=
5/95-70/30
ABS type resin 220C, 10 kg 1 - 1~0
PPE 250C~ 10 kg 1 - 100 Modified
PPE:
bein~;
included
P~ 190C, 2.16 kg 0.03 - 100
(procedure 4)
PP 230Cg 2.16 kg 0.1 - 100
(procedure 12)
:
In the following Table 4 g there are shown the
physical properties of the injection molded test pieces -~
prepared from the molding material of the present inven-
tion utilizing AS resin as thermoplastic resin as obtained
by the procedure as described in the following ~xample 1
as compared with those prepared by the methods of prior
artg namely by blending chopped strands of glass fiber .-.
with molten AS resin (reference example l)g by applying
only emulsion coating of AS resin on glass fiber roving
(reference example 2)g by applying only extrusion coating
of AS resin on glass fiber roving (reference example 3)
and by first applying a solution coating of AS resin
dissolved in methyl ethyl ketone on glass fiber rovingg
followed by extrusion coating of AS resin treference
example 4)g using the same AS resins, respectively.
Table 4
Refer- Refer- Refer- Refer-
ence ence ence ence
AS example example example example Example
resin 1 Z _ 3 4 ~
Pre-treatment None None AS None AS 20% AS
of glass emulsion MEK emulsion
fiber treat- solu- treat-
ment tion ment
alone
Glass fi~er
content in
solvent 20 20 20 20 20
separation
method)
Tensile
strength 730 1100 1100 800 850 1200
JIS K6871)
Elongation
(%; JIS 2 2 2 2 2 2
K6871)
Flexural
strength 1070 1500 1400 1400 1300 1640
ASTM D790)
Flexural
(Kg/cm2; 35 7000062000 60000 55000 73000
ASTM D790)
Izod impact 5-13 5-11
strength 1 5 5 0 7 (greatly (greatly 11
(Kg cm/cm~ ' fluc- fluc-
JIS K6871) tuated) tuated)
Heat
distortion 70 99 99 95 98 102
temperature
(Cj JIS K6871)
Dispersion of bad(in-
glass fibers suffi-
(vis.ible good bad cient good
observation glass
of injection fiber
molded plate) dis-
persion)
- 19 --
L7
Table 4 (contld)
Refer- Refer- Refer- Refer-
ence ence ence ence
AS example example example example Example
resin 1 2 3 4
Average un- un-
glass fiber measur_ measur-
length in - 0.4 mm 0.75mm able due able due 1.2 mm
the molded to the to the
article presence presence
(microscopic of glass of glass
observation fiber fiber
of glass balls balls
fibers
separated
by solvent)
Abrasion of
inJection
molding
machine
(visible None abraded abraded - - None
observation
af-ter half
year
operation)
As apparently seen from ~able 4, the glass
fiber reinforced thermoplastic resin molding composition
of the present invention can produce injection molded
articles having excellent physical properties9 being
superior over commercially available glass fiber :
reinforced AS resin (reference example 1) in impact
stren~th (Izod impact strength) by as much as twice,
and also remarkably in heat~resistance (heat distortion
temperature). Furthermoreg creep characteristics at a
high temperature are also found to be extremel.y
improvedO It is believed that such improvements in
physical properties can be ascribed to uniform disper-
sion of glass fiber filaments and longer average glass
fiber length in the thermoplastic resin of the injection
molded article produced from the pellet of the present
- 20 -
invention. ~urthermore, the injection molded article
prepared from the present molding material has physical
properties superior to those prepared from any other
material known in the art~ and the Lnjection molding
machine can be f'ree from abrasion by use of the molding
material of the present invention.
The present invention is further illustrated
by the following Examples and ~omparison example.
Example 1
~our bundles of glass fibers (2000 end, 13 ~
filaments in one bundle) are immersed in a AS resin (AN-
25 %~ M.~.R.=5 g/10 min.) emulsion with 50 % solld compo-
nents. The bundles subjected to coating treatment with
said emulsion are dried under an atmosphere at 200C.
After drying~ the AS resin coated roving contains 80 parts
by weight of glass fibers and 20 parts by weight of AS resin.
AS resin is extruded through an extruder
maintained at a barrel temperature of 160 to 180C on
the hopper side and 200 to 220C on the outflowing side
and a die temperature o~ 220C at the rate o~ 12 kg/hour
and supplied to the die. Winding speed of the emulsion
treated glass fiber bundle obtained above is controlled
at 20 m/min.~ with the diameter of the extrusion coated
strand being 3.8 mm~ and only one strand being wound up.
This s'crand is cut into pellets with 3.5 mm length by a
pelletizer. The pellet obtained contains 20 wt.% of
glass fibers~ l~ wt.% of non oriented AS resin and 76 wt.%
of oriented AS resin. The degree of orientation of the
oriented AS resin is measured at 160C by the method as
described above to be 1 % shrinkage. The pellet can be
8~L7
readily broken with pincers to be separated into broken
pieces of oriented resin and broken pieces of non-
oriented resin containing glass fibers. This pellet is
molded by conventional injection mo:Lding to obtain an
article having physical properties as shown in Table L~.
In addition to the excellent physical properties as
mentioned aboveg the dispersion of the glass fibers ln
the molded article is found to be good without ag,glo-
meration(balls) of glass ~ibers. Further, comparison is
made about the melt flow property between the AS resin
obtained by salting out the AS emulsion used in this
Example and the AS resin supplied from the extruder.
That isg melt flow properties of these resins are
measured byg for example, Melt Flow Rate measuring
device as determined in IS0 R1133 under the condition
of 220C, 10 Kg load to give the same result of 5 g/10 min.
Example 2 ;
Example 1 is repeated using an AS resin emulsion
of which AS resin after salting out has a melt flow rate
of 10 g/10 min. and anAS resin with a melt flow rate of
5 g/10 min. to be supplied from the extruderg under other-
wise the same conditions as in Example 1, to prepare a
pellet with strand diameter of 3.8 mm~ and length of
3.5 mm. By injection molding the resultant pellet by
conventional methodg there is obtained a molded article
which is bekter in uniformity of the glass fibers
dispersed in the molded article as well as surface
appearance improved in flatness and gloss. The melt
flow property(injection molding pressure) is also slightly
(by about 10 % decrease) improved. As to the physical
properties~ I~od impact strength is slightly improved to
be 13 kg-cm/cm as compared with Example 19 other
properties being comparable to those of Example 1.
Example 3
Four bundles of a glass fiber (2000 end~ 15 u~
mono~filaments in one bundle) are immersed in a styrene-
butadiene resin (St~Bd=6/4) emulsion (solid componentsO
45 %) and dried at 110C. The emulsion coated bundles
after drying contains 85 parts by weight of ~lass f'ibers
and 15 parts by weight of styrene-butadiene resin.
A polystyrene resin is extruded throu~h an extruder
maintained at a barrel temperature of 160 to 1~0C on
the hopper side and 200 to 220C on the outlet side
and a die temperature of 220C and supplied to an
extrusion coating dieO The glass fiber is wound up
at a speed of 5 ~.~min. with extruded strand diameter
being 3.2 mm~. Said strand is cut into pellets of
5 mm length. Said pellets contain 30 wt.% of the
glass f'ibers~ 5.3 wt.% of non-oriented SB resin and
64.7 wt.~ of oriented PS resin. When inJection molding
of the pellets is performed by conventional method,
the dispersion of the glass fibers is found to be good
to give an injection molded article having improved
physical properties. The styrene-butadiene resin used
in this Example has a melt flow rate of 10 g/10 min.
and the polystyrene of 3 g/10 min. (measured under the
conditions of IS0-R1133~ procedure 8).
Example 4
Three bundles of glass fiber (each bundle
comprising 2000 end filaments with diameters of 13 ~)
- 23 -
are immersed in an aqueous polystyrene resin emulsion
with solid content of 40 % to apply coating treatmen~ on
each roving~ followed by drying in an atmosphere main-
tained at 200C. The composition of the roving coated
with polystyrene resin after drying consists of ~5 parts
by weight of glass fiber and 15 parts by weight of
polystyrene resin. A mixture of polyphenylene ether
resin and polystyrene resin (PPE/PS=4/6, M.F~R.=7 g/10
min.) is extruded through an extruder at cylinder
temperature and die temperature of 270Cg respectively
at the rate of 75 kg/hour to be fed into the dieO On
the other hand, winding speed of the glass fiber roving
as prepared above ls controlled at 20 rn/minute with
diameter of extrusion coated strand of 3.2 mm, five
strands being wound up at one time. The resultant
strand is cut into pellets by a pelletizerO Glass
fiber content in this pellet is found to be 20 wt.%.
This pellet is injection molded by conventional method
to obtain a molded article having Izod impact strength
of 20 kg.cm/cm and a heat distortion temperature of
145C. ~or comparative purpose, there are prepared
pellets of a mixture of the polyphenylene ether
mixture with 20 % of glass flber prepared by blending
glass fiber with the polyphenylene ether mixture in an
extruder~ both being of the same kind as used in the
above Example. The pellets are similarly injection
molded to obtain an article having an Izod impact
strength of 10 kg-cm/cm and a heat distortion temperature
of 140C. From this comparison, the improved effect of
the present invention can be apparently seen and
24 -
the glass fibers in the molded article of the present
invention are found to be well dispersed therein without
agglomeration (balls) of glass ~ibersg exhibiting a good
appearance.
Example 5
Example 1 is repeated except that an a~ueous
emulsion (solid: 50 %) of ethylene-vinyl acetate copolymer
(vinyl acetate 28 %) is used in place of the AS emulsiong
and a high density polyethylene (density=0.950, MX=
3 g/10 min) in place of the AS resin for the extrusion
coated outer coverihg layer resin. The resultant molding
material produces a molded article improved in mechanical
properties to the same extent as observed in Éxa~p~e 1.
Comparison example
lg ~n substantially the same step as in Example 1
in place of the AS resin emulsion~ there is prepared a
20 wto% AS resin solution by dissolving an AS resin with
substantially the same molecular weight as that contained
in the AS emulsion in methyl ethyl ketone. The same
glass rovlng as used in Example 1 is immersed in said
AS resin solutiong followed by drying. The roving after
drying contalns 20 % by weight of AS resin adhered
thereon. Under the same conditions as in Example 1,
the AS resin is extrusion coated on this roving to a
final glass fiber content of 20 % by weightg followed
by pelletizingO The pellets obtained are injection
molded to ob~ain an injection molded articleg in which
glass fibers are insufficiently dispersed. The
injection molded articles have various fluctuations in
physical pro~erties~ especially Izod impact stren~th.
While there may be considered various factors which will
affect physical properties of the molded product such
as viscosity of the AS resin methyl ethyl ketone solutiong
penetration degree of the resin solution into the roving
and balance in amounts of the coating or adhesion of the
resin on the roving, it ls believed that the insufficient
dispersion of the glass fibers in the final molded
product is ascribable to still insufficient affinity
between the glass fibers and methyl ethyl ketone due to
which no complete coatinK can be applied previously on
the glass fibers.
As described above, the moldlng material of
the glass ~iber reinforced thermoplastlc resin of the
present invention is a molding material which is very
excellent in glass fiber reinforcing effect. For
molding the material of the present invention, there
can be used various molding machines known in the art
such as in~ection molding machine or an ext~uder and
the material can be used as it is when applying these
machines. Due to uniform dispersion of the glass
fibers in the material of the present invention~ it
can produce molded articles with excellent physical
properties and surface appearance of good smoothness
and gloss. Furthermoreg the oriented outer resin is
readily broken in a molding machine and the non-oriented
resin present as thin film layer around glass fibers (an
easily be molten to effect lubricating action between
glass fibers and metals in molding machines, whereby
abrasion of machines is very small. Thusg a variety of
uses will be expected of the materi~l provided by the
present invention.
~ 2~ _
