Note: Descriptions are shown in the official language in which they were submitted.
2~a~
-- 1 --
Core-Shell Pol~mer and Its IJse
The pres&nt invenl:ion relates to a core shell
polymer and a resin composition insuring high impact
s-trength and improved weld characteristics as produced
by melt-blending said core-shell polymer.
[Background of the invention]
Polyoxymethylene (PO~) resin has been employed as
a molding material in the manufacture of various parts
such as gears, reels, cord clips, etc. but because
these moldings are not good enough in impact strength,
many attempts have been made to improve PO~ resin in
this quality parameter.
However, because of the very structure of POM
resin, no blending resin is available that is
sufficiently compatible ~ith POM resin.
Furthermore, because of the high crystallinity of
POM resin, any improvement in its physical properties
that may be ob-tained by alloying with other resins
compromises its weld strength and elongation.
Moreover, because o~ its inadequate thermal stabi-
lity, POM resin is not suited for high-temperature
blending.
Heretofore a number o:E core-shell polymers have
been proposed for melt-blending for the purpose of
improving the impact strength oE matrix resins. ~ny
core-shell polymer consisting of a rubbery elastomer
core and a glassy polymer shell, in particular, has the
advantage of greater reproducibility of dispersion
uniformity because the state of its dispersion in a
matrix resin is less susceptible to the influence of
melt-blending conditions.
Such core-shell polymers have heretofore been used
as impact modifier for a variety of matrix resi.ns such
as polycarbonate, poly(butylene terephthalate),
2 ~
-- 2
polyamide, poly(phenylene oxicle), etc. as well as
various allo-~s thereo~.
However, the core-shel:l polymers heretofore avai-
lable contain ingredients that enco~lrage thermal
degradation of POM resin. q~herefore, these known core-
shell polymers can hardly be even blended with POM
resin. If they could be blerlded, the resulting
compositions would be inadequate in -thermal stability.
A POM resin composition with improved impact
strength is dlsclosed in U.S.P. ~,~04,716, for
instance. This is a POM resin composition forming
thermoplastic IPN tinterpene-trated polymer networks)
with a polyure-thane elas~omer but has many dis-
advantages. Thus, in order to ob-~ain a su~ficiently
high impact strength, it is necessary to use the
polyurethane elastomer in a fairly large proportion so
that the modulus of elasticity is markedly sacri~iced.
Moreover, it is impossible to obtain a composition
having satisfactory thermal stability, weatherability,
fluidity and weld strength and elongation
characteristics.
European Patent Laid-open Publication No. 115,373
discloses a POM resin composition containing a rubbery
elastomer prepared by emulsion-polymerization of Cl 8
alkyl acrylates. However, -the production of this com-
position requires special blending conditions and if
the ordinary blending conditions are used, a
sufficiently stable POM resin composition cannot be
obtained. Moreover, no ingenuity has been exercised in
regard to therrnal stab;lity in the emulsion
polymerization stage.
U.S.P. ~,713,~1~ discloses a POM resin composition
containing a core-shell polymer and a reactive
titanate. However, even with this core-shell polymer,
the POM resin composition is unstable, undergoing
decomposition.
Particularly the core-shell polymer used in the
examples described in ll.S.P. ~,713,~1~ and EP~A-115,373
is deficient in thermal stability (Comparative Example
1 of this specifica-tion).
Disclosed in IJ.S.P. 4,639,~ is a POM resin
composition containing a rubbery elastomer obtained by
emulsion polymerization of butadiene but here is no
exercise of ingenuity in the emulsion polymer, either,
and the thermal stability of thls composition is poor.
U.S.P. 3,749,755 discloses a POM resin composition
containing a rubbery elastomer but its thermal
stability is unsatisfactory.
Japanese Patent Examined No. 15331/19~4 discloses
a method for producing a thermoplastic resin like
acrylonitrile-acrylate-styrene (AAS resin) using
emulsion polymerization technique improved on impact
strength. This is, however, copolymer not a blend
mix-ture.
It is generally acknowledged that a polymer blend
composed of crystalline polymers is insufficient in the
strength and elongation of welds. For example, a POM
resin composition containing a poly urethane elastomer
as a blending resin for improved impact strength is
markedly compromised in weld strength and elongation.
Moreover, among engineering plastics, POM resin
does not necessarily rank high in weatherability. When
blended with a poly urethane elastomer for improved
impact strength, POM resin provides only a composi-tion
markedly compromised in weatherability.
In the above state of the art, therefore, devel-
opment of an impact modifier which, in a POM resin
composition, provides sufficient impact strength and
insures sufficient weld strength and elongation as well
as improved thermal stability has been keenly demanded.
Moreover, POM resin is particularly poor in
weatherability among various engineering plastics.
2 ~
-- 4 ~
24205-903
This parameter has not been overtly improved by the prior art
mentioned above and, therefore, development of a P~M resin
composition improved not only in impact strength but also in
weatherability has been demanded.
The inventors of the present invention explored this
field of art attempting to develop a core-shell polymer capable
of providing an improved POM resin composition and found that
the surfactant and the polymerization initiator used in the
preparation of the core-shell polymer had adverse effects on the
thermal stability of POM resin. Based on this finding, attempts
were made to improve the weld strength and elongation and
weatherability of POM resin, and it ~as ultimately discovered
that the above-mentioned problems could be solved all at once
by melt-blending a core-shell polymer of the construction
described hereinafter. The present invention is based on the
above findings.
[Detailed description of the invention]
The present invention is therefore directed to a core-
shell polymer comprising a rubbery polymer core and a glassy
polymer shell as produced by emulsion polymerization in the
presence of an oligomeric surfactant and a neutral radicals-
liberating polymerization initiator, to a process for producing
the core-shell polymer, to a polyoxymethylene resin composition
containing the core-shell polymer, and a resin product molded
from the composition.
In accordance with the present invention, an emulsion
polymerization is carried out using the following surfactant and
initiator.
~ r~ 9 ~
- 4a -
24205-903
The surfactant -to be used in the present inventio~ is
an oligomeric surfactan-t such as those which have been used in
emulsion polymerization reactions for certain special purposes.
For example, oligomeric surfactants of the following formula can
be employed.
2 ~ 5
R, R2 ~ ~ R3 Rl ~ r ~2l-1 R2n
- S(O)z ~ c- c - _ - c - c ~ c _ c _
~ 11 X~ ~1 I~ 2 JY2 ~ Xn
In the above formula, R means an alkyl group of 5
to 20 carbon atoms, preferably 6 to 12 carbon atoms; Z
is equal to 0, 1 or 2; preferably 0 or l, and more
preferably 0; n is a positive in-tegral number;
R2n~ respectively means -H~ -C~3~ -C2Hs or -COO~I;
R2n respectively means -H~ -CH3~ -C2Hs~ -COOH or
-CH2COOH; Xn means -COOH, -CONH2~ -OCH3~ -OC2~s~ -CH20H~
~ , -CONH2~ -COOC2~140H~ -COOC3H60H~ -CONHCH20H~
~J
-CO~HCH3~ -CON~C2Hs~ -CONHC3H7~ -COOCH3~ -COOC2Hs~ -CN~
-OCOCH3~ -OCOC2Hs~ or -COOCH2-~ H2-
The molecular wei.ght of the oligomeric surfactant
to be used in accordance wi.-th the invention is about
200 to 5000, preferabl.y about 1500 to 3000, with the
degree of polymerization (~lYa) ranging from about 6 to
50.
The oligomeric surfactant as such may be water-
soluble. If not, it is converted to a water-soluble
salt by reacting with an oxide, hydroxide or alcohol.
The water-soluble salt mentioned just above in-
cludes, among others, alkali metal salts, alkaline
earth metal salts, Group III heavy me-tal salts,
ammonium salt, substituted ammonium ~alts, e-tc.~ and
most preferably the ammonium salt.
These oligomeric surfactants can be synthesized,
for example as described in Japanese Patent Publication
No. 47-34832, by addition-polymerizing relevant
monomers in an anhydrous sol.vent in the presence of an
2 ~ j ! t
-- 6
alkyl mercaptan or further oxid:izing the oligomer with
hydrogen peroxide or ozone -to the corresponding
sulfoxide or su:lfone.
The alky:L mercapl:an merltiorled above incl~ldes,
among others, n-octyl mercaptan, n-dodecyl mercap-tan,
t-dodecylmercaptan, n-decyl mercaptan and 90 on.
The monomers mentioned above include ~,~-ethylen-
ically unsaturated monomers having at least one polar
group, such as (meth)acrylic acid, ~-ethyl acrylate,
10 ~-methyl acrylate, ~,~-dimethyl acrylate, caproic acid,
itaconic acid, fumaric acid, maleic acid, (meth)acryl-
amide, vinyl ethyl ether, vinyl methyl ether, allyl
alcohol, vinylpyrrolidone, (meth)acrylonitrile, ethyl-
acrylonitrile, methyl (meth)acrylate, ethyl acrylate,
15 hydroxyethyl ~meth)acrylate, hydroxypropyl
(meth)acrylate, vinyl acetate, vinyl propionate, N-
isoproylacrylamide, N--ethylacrylamide, N-
methylacrylamide, glycidyl (meth) acrylate, N-me-thylol-
acrylamide and so on.
The solvent used for the above-mentioned addition
polymerization is preferably a lower alkanol such as
methanol, ethanol, isopropyl alcohol and so on.
The above addition polymerization is generally
carried out in the temperature range of about 20 to
25 100C.
The proportion of said oligomeric surfactant in
the prac~ice of the present invention is selected with
reference to the particle stabilizing power of the
surfactant.
In the present invention oligomeric anionic
surfactant is used preferably.
The neutral radicals-liberating polymerization
initiator includes initiators of the azo typel such as
azobis (isobutyronitrile), dimethyl 2l2'-azobis (iso-
35 butyrate), 2,2'-azobis (2-amidinopropane)
dihydrochloride, etc. and peroxides such as cumene
~ 3
-- 7
hydroperoxide, diisopropylbenzene hydroperoxide,
hydrogen peroxide and so on. These ini~iators can be
used independently or in combina-tion.
The emulsion polymerization in a reaction system
containing said oligomeric surfactant and ini-tiator
gives rise to a core-shell polymer which is sub-
stantially free of sulfur oxide compounds or lean in
sulfur oxide compounds.
The low sulfur oxide compound (e.g. sulfate,
persulfate, etc.) content means tha-t the result of an
ordinary qualitative test for sulfate ions is negative.
R typical test is as follows. Five grams of a
sample (core-shell polymer) is weighed into a 50 ml
conical ~lask, 20 ml of deioni~ed water is added and
the mixture is stirred wi-th a magnetic stirrer for 3
hours at room temperature.
The mixture is then ~ilterecl through a No. 5 C
filter paper and the filtrate is divided into halves.
To one of the halves is added 0.5 ml of 1% barium
chloride aqueous solution and the relative turbidity of
the halves is evaluated (qualitative test for sulfate
ion).
The impact streng-th of a POM resin composition
containing such a core-shell polymer, particularly one
free of sulfur oxide compounds, is very excellent.
The core-shell polymer according to the present
invention can be produced by the so-called seeded
emulsion polymerization method, which is a serial
multi-stage emulsion polymerization method in which a
polymer formed in the preceding stage is covered with a
polymer formed in the following stage.
It is preferable that in the seed particle-forming
stage, the monomer, surfactant and water be fed to the
reactor and, then, the initia-tor be added so as to
initiate the emulsion polymerization reaction.
The first-s-tage polymerization i.5 the reaction
forming a rubbery polymer.
The monomer for cons-tituting such rubber polymer
includes, among others, conjugated dienes and alkyl
acrylates contai~ing 2 to 8 carbon atoms in the alkyl
moiety, as well as mixtures thereof.
Such a monomer or monomers is polymerized to give
a rubbery polymer with a glass transition -temperature
of not higher than -30C.
Among said conjugated dienes can be reckoned buta-
diene, isoprene, chloroprene ancl so on, although
butadiene is particularly pre~erred.
Among said alkyl acrylates whose alkyl moieties
contain 2 to ~ carbon a-toms each are ethyl acrylate,
propyl acryla~e, bu-tyl acrylate, cyclohexyl acryla-te,
2-ethylhexyl acrylate and so on, although bu-tyl
acrylate is particularly desirable.
In this -First stage polymerization reaction, mono-
mers copolymerizable with said conjugated dienes and/oralkyl acrylates can be copolymerized. ~nong such
monomers can be reckoned various aromatic vinyl or
vinylidene compounds such as styrene, vinyltoluene, ~-
methylstyrene, etc., vinyl or vinylidene cyanide
compounds such as acrylonitrile, methacrylonitrile,
etc., and alkyl methacrylates such as methyl
methacrylate, butyl methacrylate and so on.
When the first-stage polymerization system does
not contain a conjugated diene or, if i-t does, in a
proportion of not more than 20 weight % o~ the total
monomer ~or the first-stage reaction, an improved
impact strength can be implemented by incorporating a
crosslinking monomer and a grafting monomer in small
proportions. The crosslinking monomer mentioned above
includes, among others, aromatic divinyl monomers such
as divinylbenzerle etc., and alkane polyol polyacrylates
or polymethacrylates such as ethylene glycol
diacrylate, ethylene gl~col dimethacrylate, but~lene
glycol diacrylate, hexanediol diacr~late, haxanediol
dimethacrylate, oligoet:hylene glycol diacrylate, olio-
ethylene glycol dimethacr~late, trimethylolpropane di-
acrylate, trlmethylolpropane dimethacrylate,
trimethylolpropane -triacrylate, trimethylolpropane
trimethacrylate and so on. Parti.cularly preferred are
butylene glycol diacrylate and hexanediol diacrylate.
The grafting monomer includes, among others, allyl
esters of unsaturated carboxylic acids, such as allyl
acrylate, allyl methacrylate, diallyl maleate, diallyl
fumarate, diallyl i-taconate and so on, although allyl
methacrylate is particularly preferred.
The above crosslinking monomer and grafting
monomer are used in a proportion o~ 0.01 to 5 weigh-t %
each, preferably 0.1 to 2 weight % each, based on the
total monomer for the first-stage polymeri~ation
reaction.
The rubbery polymer core preferably accounts for
50 to 90 weight % of the total core-shell polymer. If
the proportion of the core is either below or above the
above-mentioned range, the resin composition prepared
by melt-blending the core-shell polymer may not be
improved well in impact strength.
Moreover, the low-temperature impact strength may
not be adequately improved if the glass transition tem-
perature of the core is higher than -30C.
The outer phase of the core shell polymer is con
stituted by a glassy polymer.
As examples of the monomer constituting the glassy
polymer, there may be mentioned methyl methacrylate and
various monomers copolymerizable with methyl
methacrylate.
This monomer is either methyl methacrylate as such
9 ~
-- 10 --
or a mixture of methyl methacrylate and one or more
other monomers copolymerizable ~:ith me-thyl
methacrylate, and forms a cJlassy polymer with a glass
transition temperature of not lower than 60C.
The monomers copolymerizable with methyl meth-
acrylate include various vinyl polymerizable monomers,
e.g. alkyl acrylates such as ethyl acrylate, butyl
acrylate, etc., alkyl methacrylates such as ethyl meth-
acrylate, butyl methacrylate, etcO, aromatic vinyl or
vinylidene compounds such as s-tyrene, vinyltoluene, ~-
methylstyrene, etc., and ~inyl or vinylidene cyanides
such as acrylonitrile, methacrylonitrlle and so on.
Particularly preferred are ethyl acrylato, styrene and
acrylonitrile.
This outer shell phase preferably accounts for 10
to 50 weight % of the total core-shell polymer. If the
proportion of the shell phase is below or above the
above-mentioned range, the resin composition prepared
by melt-blending the core-shell polymer may not be
improved sufficiently in impact strength.
An intermediate phase may be interposed between
the first-stage polymer phase and the final-stage
polymer phase. Such an intermediate phase can be
provided by subjecting a polymerizable monomer having
functional groups, such as glycidyl methacrylate,
unsaturated carboxylic acids, etc., a polymerizable
monomer forming a glassy polymer such as methyl
methacrylate, or a polymerizable monomer forming a
rubbery polymer such as butyl acrylate.
A variety of intermediate phases can be selected
according to the desired properties of the core-shell
polymer.
The polymerizing proportions may be appropriately
chosen according to the monomers used. For example,
when a glassy polymer is to be used as the intermediate
1 1 - 2 ~
phase, its polymerizing ratio can be calculated
assuming this phase as a part of the shell and when -the
intermediate phase is a rubbery pol~mer, i-~s ratio can
be calculated as a part of the core.
The structure of a core-shell polymer having such
an intermediate phase may, for example, be a multi-
layer system including an additional layer between a
core and a shell or a salami-like sys-tem in which an
intermediate layer is dispersed as small particles in
the core. In a core-shell polymer of the salami type,
the intermediate phase which i~ usually dispersed may
form a new core in the center of the core polymen.
Such a core-shell polymer is sometimes formed when
styrene or the like is used as the monomer for
constituting the intermediate phase.
The use of such a core-shell polymer having an
intermediate phase results not only in improvements in
impact strength but also improved flexural modulus,
increased heat distortion temperature and improved
appearance (molding delamination and pearlescence,
variation of color due to change in refractive index).
The core-shell polymer of the present invention
can be made available in the form of granules, flakes
or powders, for example by the following procedures.
(1) A latex is produced by the per se known seeded
emulsion polymerization method in the presence of said
surfactant and initiator.
(2) This latex is then subjected to the freqze-thaw
cycle to separate the polymer.
(3) Then, the polymer is dehydrated centrifugally and
dried.
By the above recovery procedure, the solvent and
surfactant used in the emulsion polymerization can be
largely removed.
Alternatively, at step (2) above, the latex as it
is may be dried and used.
2~3~ ~b
- 12 -
The spray-drying method using a spray drier can
also be utilized for recovery oi -~he core-shell polymer
from the latex.
The core-shell polymer thus isolated may be pro-
cessed into pellets by means of an extruder or
pelletizer or be directly melt-blended with matrix
resin for achieving improved impact strength.
The POM resin composition of the present invention
contains 5 to 100 weight parts, pre-ferably 10 to 80
weight parts, of said core-shell polymer based on 100
weight parts of POM resin.
If the proportion of the core-shell polymer is
less than 5 weight parts, no improvement may be
realized in impact strength, while the use o~ the core-
shell polymer in excess of 100 weight parts may xesult
in marked decreases in the rigidity and thermal
properties of the product resin.
The POM resin which can be used in the present
invention may be a homopolymer of formaldehyde or a co-
polymer of formaldehyde or a cyclic oligomer thereof
with an alkylene oxide containing at least 2 geminal
carbon atoms in the backbone chain and any of such
polyoxymethylene homopolymer resins and
polyoxyrnethylene copolymer resins can be employed.
In the production of a POM resin composition
according to the present invention, the melt-blending
method is employed.
Melt-blending is generally performed in an appro-
priate temperature range between 1~0C and 240C,
where the resins melt and the viscosity of the
composition will not be too low.
The melt-blendinc3 operation can be performed using
a calender, Banbury mixer or a s:inc31e-screw or multi-
screw extruder.
The resin composition of the present invention may
further contain various additives and other resins in
~J ~ ?j ~
- 13 -
appropriate proportions.
Among the additives rnentioned above are flame
Letardants, mold releases, wea-ther resistance agents,
antioxidants, antistatic agents, heat resistanc~
agents, colorants, reinforcements, surfactants,
inorganic fillers, lubricants and so on.
The resin compositions of -the invention may be
molded into ar-ticles of desired shapes, by ordinary
molding techniques such as injec-tion molding, extrusion
molding, compression molding and so on, at a
temperature of 200-300C.
The core-shell polymer of the present invention,
when melt-blended with POM resin, imparts an excellent
impact strength.
Moreo~er, the resin composi-tion containing the
core-shell polymer of the invention is more thermally
stable than the corresponding resin composition
containing any of the known core-shell polymers and
displays better fluidity, thermal stability,
appearance, weatherability and weld strength and
elongation than the resin composition containing a
polyurethane elastomer.
[Examples]
The following working examples and reference exam-
ple are intended to illustrate the present invention infurther detail and should by no means be construed as
limiting the metes and bounds of the invention. It
should be understood that, in the working and reference
examples, all parts are by weight. The following
abbreviations are used in the examples.
Styrene St
Acrylonitrile AN
Ethyl acrylate EA
Methyl methacrylate M~A
2-Ethylhexyl acrylate 2EHA
Butadiene Bd
- 14 -
Butyl acrylate BA
1,4-Butylene glycol diacrylate BGA
Allyl methacrylate AQMA
Methacrylamide MAM
Methacrylic acid MAA
2,~' Azobis(isobutyronitrile~ AIBN
Deionized water DIW
2,2'-Azobis(2-amidinopropane) dihydrochloride V50
(Wako Pure Chemicals, V50)
Hydrogen peroxide H2O~
Vitamin C (ascorbic acid) VC
Sodium persulfate SPS
Sodium octylsulfosuccinate NP
(Neocol P, Dai-ichi Kogyo Seiyaku Co. Ltd.)
OS soap (potassium oleate, Kao Corporation) OS
Tetrasodium ethylenediaminetetraacetate EDTA
Dodecyl mercaptan DMP
Oligomeric surfactant Surfactant A
This surfactant was synthesized as in Example 13
20 described in Japanese Kokai Patent Application No. 53-
10682, adjusted to pH 7.5 with aqueous ammonia and
diluted with purified water to make a solid content of
10%.
~ J3 ~ 3
n-dodecyl- S - ¦-C-C ~ C-C
Il COVC~13 a }I COOI~ b
(wherein a:b = 7:3, a -~ b = 13.6
[Composition]
MAA 155 g
MMA 360 ~
n-DMP 109 g
AIBN 4.4
Isoprop~l alcohol 314 g
Molecular weic3ht 1310
- 15 -
Oligomeric surfactant Surfac-tant B
This surfactant was synthesized as follows;
A 7-liter pol~meriza-tion reactor equipped wi-th a
reflux condenser was charged wi-th 1550 g of isopropyl
alcohol, 231 g of MMA, 546 g of MAA, 137 g of
hydroxyethyl acrylate and 170 g of t-DMP, and the
charge was heated to 60C with stirring in a nitrogen
stream. Then, 21 g of AIBN was added to initiate a
polymerization, and the internal temperature was
increased to 75C. The reaction mix-ture was cooled to
not more than 40C, then 2000 g of DIW was added
thereto, and adjusted -to p~l 7.5 with aqueous ammonia.
Isopropyl alcohol was distilled off under reducted
pressure, and it was dilut~d with DIW to make a solid
content of 10~.
r~ l~3 ~ r' I ~ r~Cl~3~
n-dodecyl-S- -C-C - ~I-C-C - - ¦-C-C - - H
~ COOCH3 ~H COOC2~0 lH COO~ C
[wherein a:b:c: 47:24:129, a ~ b -~ c = 39.3,
Molecular weight 3500~4000] )
Example 1 Production of core-shell polymer A
A 7-liter autoclave was charged with 975 g of DIW,
1.47 g of 25~ aqueous am~lonia, 10.5 g of surfactant A,
and 0.525 g of MAM and, after nitrogen purging, the
internal temperature was increased to 70. A seed
monomer mixture of the following composition was then
added and dispersed over l0 minutes, after which 10.5 g
of a 10~ aqueous solution of V50 was added for the
formation of seed particles.
Seed monomer mix-ture
EA 51.608 g
AQMA 0.263 g
BGA 0.105 g
Then, 1168.8 g of DIW, 21 g of surfactant A, 4.2 g
3 ~ ~ 3
- 16 -
of 25% aqueous ammonia, 10.5 g of a 10% aqueous
solution of EDTA, 0.525 g of t-DMP and 3.497 g of MAM
were added and the temperature was increased to 70C.
Then, 10O92 g of an initiator solution of the
following composition was added to lnitiate the core
polymerization.
Initiator solution
10% V50 105.0 g
25% Aqueous ammonia 4.2 g
Then, the following core monomer mixture and sur-
factant solution were continuously fed over a period of
240 minutes. The balance of the initiator solution was
fed over 480 minutes. After completion of feed, the
mixture was stirred for 12 hours to give a core latex.
Core monomer mixture
Bd 420.00 g
2EHA 376.~5 g
MMA 195.30 g
Surfactant solution
Surfac-tant A 105.00 g
5~ Aqueous MAM 35.07 g
Shell polymerization was initiated by adding 14.5
g of the following initiator solution.
Initiator solution
10% V50 13.5 ~
25% Aqueous ammonia 0.9 g
Thereafter, the following shell monomer emulsion
was continuously fed over 120 minutes for further
seeded polymerization.
Shell monomer emulsion
MMA 404.1 g
EA ~5 0
BGA 0.9 g
Surfactant A 27.0 g
DIW 630.0 g
25% Aqueous ammonia 0.54 g
3 ~
17 -
The temperature was increased to 90C and the
reaction mixture was kept ~or 1 hour. Af-ter cooling,
the mixture was filtered -through a 300-mesh stainless
steel screen to give a core-shell pol~ner latex.
This latex was frozen, filtered through a glass
filter and dried.in an air current at 40C for 24 hours
to give core-shell pol~er A.
Example 2 Production of core-shell polymer B
A 5-li-ter polymerization reactor equipped with a
reflux condenser was charged with 1.200 g of DIW, 1.68 g
of 25% aqueous ammonia, 7 g of surfactant A and 0.14 g
of MAM and the charge was heated to 70C with stirring
in a nitrogen stream. Then, 27.86 g of a seed monomer
mixture of the following composition was added and
dispersed over 10 minutes, followed by addi-tion of 21 g
of a 10% aqueous solution of V50 to initiate a seed
polymerization.
Seed monomer mixture
EA 27.664 g
AlMA 0.14 g
BGA 0.056 g
After 7 g of MAM was added, a monomer emulsion
prepared by adding 210 g of surfactant A, 900 g o DIW
and 2.80 g of 25% aqueous ammonia to 1400 g of a core
monomer mixture of the following composition and a
mixture of 21.0 g of a 10% aqueous solution of V50 and
0.63 g of 1% aqueous ammonia were continuously fed over
180 minutes for further seeded polymerization
Core monomer mixture
BA 1215.2 g
MMA 140.0 g
BGA 2.8 g
AlMA 7.0 g
The reaction temperature was increased to 80C for
keeping for 1 hour and, then, cooled to 70C.
After 9 g of a 10% aqueous solution of ~50 and
- 18 -
0.27 g oE 1% aqueous amlnonia were added, the following
shell monomer emulsion, 12 g of a 10% aqueous solution
of V50 and 0.36 g of 1% aqueous ammonia w~re
continuously fed over 60 minutes for further seeded
polymeriza~ion.
Shell monomer emulsion
MMA 540.0 g
EA 60.0 g
Surfactant A 30.0 g
DIW 500.0 g
25% Aqueous ammonia 0.92 g
The temperature was increased to 80C, where the
mixture was kept for 1 hour. After cooling, the
reaction mixture was filtered through a 300-mesh
stainless steel screen to give a core-shell polymer
latex.
This latex was frozen at -15C, filtered through a
glass filter and dried in an air current at 60C for 2
hburs to give core-shell polymer B.
Example 3 Production of core-shell polymer C
According to the method of Example 1, core-shell
polymer C was produced using surfactant B instead of
surfactant A.
Example 4 Production of core-shell polymer D
A 2-liter polymerization vessel equipped with a
reflux condensex was charged with 600 g of DIW and 20 g
of surfactant B and the mixture was stirred under a
nitrogen stream and heated to 35C. 35 g of EA was
added to the above mixture and dispersed for 10
minutes. 12 g of a 3% aqueous solution of H2O2 and 12
g of a 2~ aqueous solution of VC were added for
polymerization of seed latex.
665 g of a core monomer mixture of the under-mentioned
composition was mixed with 135 g of surfactan-t B and 95
g of DIW. Then, the mixture was ~ed to the reaction
mixture over a period of 2~0 minutes, followed ~y 72.5
~ 3
- 19 -
g of a 3% a~ueous solution of H~O2 and 72.5 g of a 2%
aqueous solution of VC were continuously fed over a
period of 300 minutes for seeded polymerization. While
the monomer solution was fed, the reaction -temperature
was kept at the range from 35C to 40C.
Core monomer mixture
BA 697.20 g
AlMA 1.40 g
BGA 1.40 g
The reaction mixture was kept for one hour at the
same temperature after finish of feeding monomers, and
was subject to the shell pol~merization.
32.9 g of a 3~ aqueous solution of H2O2 and 32.~ g
of VC was fed to the reaction mixture over a period of
15 150 minutes, and 431 g of a shell monomer emulsion of
the under-mentioned composition was continuousl~ fed
over a period of 90 minutes for seeded pol~nerization.
While the monomer solution was fed, the reaction
temperature was kept at the range from 35C to 40C.
Shell monomer emulsion
St 240 g
AN 60 g
Surfactant B ~7.0 g
DIW 102.0 g
The reaction mixture was kept for one hour at the
same temperature, then, cooled and filtered through a
300-mesh stainless steel sieve to give a core-shell
polymer latex.
This latex was frozen at -15C and filtered
through a glass filter. The solid was then dried in a
current of air at 60C overnight to give core-shell
polymer D.
The compositions of core-shell polymers A to D are
shown in Table 1.
Example 5 Production of POM resin composition (1)
Seventy parts of Tenac C4510, a POM copolymer
2~ 3
- 20 -
.resin o Asahi Chemical [ndustry Co., Ltd., and 30
parts of core-shell polymer A prepared ln Example 1
were dried to a moisture con-tent of not rnore than 0.3%
and using a twin-screw extruder (PCM-30; Ikegai
Corporation), the mixture was melt-blended a-t a
cylinder temperature o~ 200C and a die head
temperature o~ 200C to give pellets of POM resin
composition (1).
Examples 6 to 12 Production of POM resin compositions
(2) to (8)
In the same manner as Example 5, pellets o~ POM
resi.n compositions (2) to (8) were produced according
to the formulas shown in Table 2.
Comparative Examples 1 and 2 Production of core-shell
polymers E and F
In the same manner as Example 4, core-shell
polymers E and F were produced according to the
compositions shown in Table 1.
Comparative Examples 3 to 7 Production of POM resin
compositions (9) to (13)
In the same manner as Example 5, pellets of POM
compositions (9) to (13) were produced according to the
formulas shown in Table 2.
Impact strenqth testinq of resin prodllcts
Resin compositions (1) through (13) were dried at
110C for 1 hour and using an injection molding machine
(TS-100, Nissei Plastics Co.), each composition was
molded at a cylinder temperature of 200C and a nozzle
temperature of 200C.
Notched Izod testpieces, 3.2 mm -thick, were
prepared in accordance with JIS K7110. The impact
strength of these testpieces were measured at 23C in
accordance with ~IS K7110.
Incidentally, melt-blending could not be made with
POM resin compositions (10) and (11) (Comparative
Examples 4 and 5). The results of blending are shown
~S,)~3~"~
- 2] -
below in the table 2.
Determination of welcl e~ ion reten-tion rates of
resin products
Using testpieces conforming to JIS k7113
, the ratio of the elonga-tion at break of a testpiece
with two point g~tes a-t both ends to that of a
testpiece with a one-poin~ gate at one end was
determined by the tensile test method according to JIS
k7113. The results are set forth in the table 2.
[Weatherability Test]
The color difference between non-exposed and
exposed injection molded specimen obtained from POM
resin compositions (5) and (13) by the Sunshine Super
Long-Life Weather Meter~ (Suga Test Instruments) were
measured using ~80 Color Measuring System~ (Nippon
Denshoku Kogyo).
The results are shown in Table 3.
[Thermal Stability Test]
The color difference between non-kept and kept
injection molded specimen obtained from POM resin
compositions (5) and (13) in the drier setting at 150C
for 50 hours were measured using ~80 Color Measuring
System~.
The results are shown in Table 3.
[Thermal s-tability Test (]cept melting)]
The color difference between non-kept and kept
injection molded specimen obtained from POM resin
compositions (5) and (13) in the in~ection molding
system setting the cylinder temperature of 230C before
molding, were measured using **80 Color Measuring
System~.
The results are shown in Table 3.
[Qualitative test for sulfate ion]
The sulfate ions in core-shell polymers A ~o E,
KM-330 were determined.
Thus, 5 g of each sample was weighed into a 50 ml
- 22 -
conical flask, 20 ml of deionized water was added and
the mixture was stirred with a magneti.c stirrer for 3
hours.
The mixture was filtered through a No. 5 C filter
paper and the filtrate was divided into halves. Then,
0.5 ml of a 1~ aqueous solution of barium chloride was
added to one of the halves and the relative turbidity
of the two halves was examined.
In this qualitative test, no sulfate ion was
detected in core-shell polymers A to D but sul-fate ions
were detected in core-shell polymers E and KM~330.
- 23 -
Table 1 Compositions of Core-Shell Polymers
_~_ _
Ex. No. 1 2 3 4 Comp. Comp.
Ex. 1 ~x. 2 l
I _ I
Impact Modifier A B C D E F
Core
, 11
BA 60.76 _ 66.234 79.68 69.51
BGA 0.0070.1428 0.007 0.133 0.16 0.14
AQMA 0.0180.357 0.018 0.133 0.16 0.35
Bd 28.1 _ 28.1 _ _ _
_
MMA 13.05 7.0 13.05 _ _ _
I - _ ._
EA 3.451.3832 3.45 3.5 _ _
I -- _
2EHA 25.2 _ 25.2 _ _ _ l
_ I
MAM O.12 O.357 O.12 _
. _
Core/MID//Sh01170//30 70//3070//3070//30 80//2070//30
Shell _
I
MMA 27.0 27.027.0 _ 18.0 27.0
I _
EA 3.0 3.0 3.0 _ 2.0 3.0
_
BGA 0.06 _ _0.06 _
AN _ _ _ 6.0 _ _
I
St _ _ _ 24.0 _ _
I .
Surfactant A A B B NP OS
¦ Polymeri~ation V50 V50 V50 H202/VC SPS V50
Initiator
, _ _
~ J
- 2~ -
Table 2
. _
¦ Examples 5 6 7 8 9 10 11 12
Resin (1) (2) (3)(4) (5) (6) (7) (8)
composition _
Impact (A) (B) (D)(C) (C) (C) (C) (C)
Modifier
I
Ratio of POM
to Impact
Modifier
POM-l 70 70 100100 100 100
POM-2 100
POM-3 100
Impact
Modifer30 30 40 40 20 60 40 40 l
_ I
Izod impact 31.218.0 14.8 33.9 22.1 38.2 41.6 35.1
(kgf-cmlcm) l
. _ I
Elongation(%) 70/200 601170
(with
weldIwithout
weld) . l
- I
POM-1: Tenac C4510
(Asahi Chemical Industry Co., Ltd.; POM copolymer)
POM-2: Tenac C3510
(Asahi Chemical Indus-try Co., Ltd.; POM copolymer)
POM-3: Tenac 4010
(Asahi Chemical Industry Co., Ltd.; POM homopolymer)
2 ~ ~5 J JA ~
- 25
Table 2 (Continued)
Examples Co~p. 6x, Comp. Ex. 4 Comp, Ex. 5 Col~p. ~. 6 ~ 7
Resin (9) (10) (11) (12) (13)
composition
_
Impact (E) (F) KM-330 TPU TPU
¦Modifler
Ratlo oflOO/40 100/40 100140 100/40 100/20
POM-l to
Impact
¦ Modifier
Izod impact _* _* _* 13.6
(kgf cm/cm)
_
Elongation _* _* _* 2.8/400
weld/without
KM-330 : impact modifier (Rohm & Haas Co.)
TPU ; polyurethane elastomer; Elastollan ET-680-10 (Takeda Badische
Urethane Industries, LTD.)
* The resin compositions (9) and (11) (Comparative Example~ 3
and 5) foamed copiously owing to decomposition of POM during
blending and could not be molded.
The resin composition (10) (Comparative Example 4) made smoke
and had discolored during blending.
Table 3
Resin compositions (5) (13)
Weatherability (~E) 0.90 11.0
Thermal stability(~E) 3.5 12.1
Thermal stability 1.2 5.8
(kePt melting~ (~E)
~ ,
