Note: Descriptions are shown in the official language in which they were submitted.
11223SO
The present invention relates to a composition
suitable for manufacturing a polyvinyl chloride-based resin foam.
In the prior art, polyvinyl chloride-based resin foams
(hereinafter abbreviated as PVC resin foams) have been
manufactured by several different processes. For example, (1)
the resin is blended or impregnated with a decomposable foaming
agent, which is a compound decomposable at an elevated tempera-
ture with evolution of a gas, and the resin blend is fabricated
with heating by the techniques of extrusion molding, injection
molding or other conventional molding means whereby the resin
is expanded into a foam by the gas produced by the decomposition
of the foaming agent; (2) a so-called plastisol of pasty
consistency is first prepared by admixing the resin with a
plasticizer and the plastisol is processed into a foam with
entrainment of air by a suitable mechanical means or,
alternatively, the plastisol is further admixed with a
decomposable foaming agent and the blend is heated, whereby,
the foaming agent is decomposed to produce a gas simultaneously
; with the gelation of the plastisol; (3) a resin blend containing
a decomposable foaming agent is first fabricated into shaped
` articles such as plates, slabs, rods, tubes and the like by
rolling or other suitable mechanical means at a temperature
lower than the decomposition temperature of the foaming agent
and then the shaped articles are heated to effect expansion
into foam by the decomposition of the foaming agent; or (4) a
metal mold is filled with a resin blend containing a decomposable
foaming agent, optionally, with admixture of a volatilizable
foaming agent, an organic solvent with which the resin is
swellable and a softening agent, and the resin blend is heated
under pressure in the metal mold, to produce a melt which gells,
`:
. ~ ~
,
112Z3S()
followed by cooling to room temperature while still in the metal
mold and under pressure to give a shaped article, which is
subse~uently heated again at a temperature higher than the
softening temperature of the resin to effect expansion of the
resin blend into a foam with the gas produced by the decomposi-
tion and/or vaporization of the foaming agents.
As is understood from the above description, the gas as
the entity which effec~s expansion of the resin blend and is
confined in the PVC resin foam is mostly either the atmospheric
air entrained by a mechanical means or a gas which is a
decomposition product of the decomposable foaming agent. The
mechanical entrainment of atmospheric air is, however,
unsatisfactory because foams of fine and uniform cell structure
and high expansion can not readily be obtained even by the use
of a very elaborate mixing apparatus. The use of a decomposable
foaming agent is undesirable when a white PVC resin foam is
desired, because, most of the practically employed decomposable
foaming agents are azo compounds which form colored decomposition
products leading necessarily to yellowish or brownish coloring
of the resin foam manufactured therewith. Furthermore, the
cell structure of a resin foam obtained with a decomposable
foaming agent is not always satisfactory in its fineness and
uniformity, especially, when a resin foam of high expansion
is desired.
In addition to the above drawbacks, the above
described methods (1) to (3) are not suitable for the
preparation of rigid or semi-rigid foams of high expansion, i.e.
the methods are limited to the manufacture of soft or flexible
resin foams; and method (4) is disadvantageous from the stand-
point of efficiency and production cost as the process must be
- 2 -
B
l~Z23~0
carried out batch-wise and the time taken for the preparation
of a batch of the foam is long due to the complexity of the
process.
Another source of gas for resin foams is a
volatilizable foaming agent which is a compound of relatively
low boiling point and which is readily converted to a gas when
the resin blend containing it is heated. Thus, if the heating
temperature is above the softening point of the resin, resin
foams are obtained. This class of foaming agents is desirable
owing to the absence of colored decomposition products, leading
to the coloration of the resin foams, since the formation of the
gas is effected not by the decomposition but merely by the
vaporization of the foaming agent.
; The use of a volatilizable foaming agent has been
successful in the manufacture of several kinds of plastic foams
such as polystyrene resin foams, but no successful process
has been developed hitherto for the preparation of PVC resin
foams, although the reason for the difficulty has not yet been
completely analyzed.
Thus, an object of the present invention is to
provide a composition suitable for manufacturing PVC resin
foams containing a foaming agent of the volatilizable type.
According to an aspect of the invention there is
provided a resin composition expandable into a foam by heating
which comprises 100 parts by weight of a polyvinyl chloride-based
resin having an average degree of polymerization not exceeding
2,000 and a pore volume not exceeding 0.20 ml/g; and at least 1
part by weight of a volatilizable foaming agent selected from
the group consisting of a hydrocarbon, a halogenated hydrocarbon
and mixtures thereof having a boiling point not exceeding 90C
and impregnated in said polyvinyl chloride-based resin.
-- 3 --
11223SO
The main ingredient of the compositions described
herein is a PVC resin which may be a homopolymer or a copolymer
mainly composed of vinyl chloride. When the PVC resin is a
copolymer, it is preferable that the proportion of the monomer
or monomers copolymerized with vinyl chloride not exceed 40% by
weight or, in other words, at least 60% by weight of the resin
constituents should be vinyl chloride, from the standpoint that
the resultant resin foams may have excellent flame retardancy,
high mechanical strength and other desirable properties inherent
to vinyl chloride resins.
The ethylenically unsaturated monomers copolymerizable
with vinyl chloride are well known in the art as exemplified
by vinyl esters such as vinyl acetate and vinyl propionate;
vinylidene halides such as vinylidene chloride and vinylidene
fluoride; vinyl halides other than vinyl chloride such as
vinyl fluoride; acrylic acid and esters thereof such as ethyl
acrylate; methacrylic acid and esters thereof such as methyl
methacrylate; acrylonitrile, methacrylonitrile; maleic acid
- and esters and anhydride thereof; fumaric acid and esters
; 20 thereof; and olefins such as ethylene and propylene.
Among the above named comonomers, vinyl acetate is
most preferred since a copolymer of vinyl chloride and vinyl
acetate not only is susceptible to impregnation with a foaming
agent but also has a markedly reduced melt viscosity so that
smoothness in foaming is ensured leading to the formation of
resin foams with a further improved fine and uniform cell
structure. In order that such an advantageous effect can be
expected by the use of the copolymer, the content of vinyl
acetate in the copolymer resin is preferably at least 3~ by
weight with the upper limit being 40~ by weight as set forth
above.
-- 4 --
'.~
~lZZ3SO
The essential parameters for the PVC resins used in
the resin compositions described herein are the average degree
of polymerization and the pore volume. The average degree of
polymerization, which is readily determined by the measurement
of the solution viscosity of the resin, preferably does not
- exceed 2,000since a PVC resin having an average degree of
polymerization larger than 2,000 has an extremely high melt
viscosity and poor gelation so that resin foams of high expansion
can not readily be obtained even with a large amount of the
foaming agent impregnated in the resin. On the other hand, the
lower limit of the average degree of polymerization is deter-
- mined in consideration of the desired mechanical properties
of the resin foams prepared with the resin. For example, a
PVC resin having an average degree of polymerization of less
than 300 can only give fragile and mechanically inferior resin
foams.
The other important parameter for the PVC resin is
the pore volume which preferably does not exceed 0.20 ml/g or,
more preferably, 0.10 ml/g of the resin. This value of the
pore volume is rather small in comparison with ordinary PVC
resins which have pore volumes of about 0.25 ml/g or more, when
the resin is a homopolymer of vinyl chloride. The pore volume
is a value determined with a mercury-pressurizing porosimeter
where the mercury pressure is increased from 1 to 100 kg/cm2 so
- that the mercury is forced into pores of the resin particles
having a pore diameter of about 30 ~m or less.
The above limitation of the pore volume is essential
because a PVC resin having a larger pore volume is poor in
retention of the foaming agent and permits dissipation of the
foaming agent not only during storage of the resin composition
~,
112Z3SO
impregna-ted with the foaming agent but also in the molding
process of the resin composition into a shaped article of resin
foam, hence, foamed bodies of high expansion can not readily
be obtained.
The PVC resins which can meet the above requirements
are obtained by the suspension polymerization of vinyl chloride ;:
monomer or a monomer mixture mainly composed of vinyl chloride
monomer in an aqueous medium containing a suspending agent in
the presence of a free radical polymerization initiator soluble
in the monomer phase.
The volatilizable foaming agent to be impregnated in
the above described PVC resins is, as mentioned above, a hydro-
carbon or a halogenated hydrocarbon compound having a boiling
point not exceeding 90C or, preferably, not exceeding 70C.
~hen a foaming agent having a boiling point higher than 90C
is employed, the resin foams once expanded exhibit extensive
shrinkage upon standing so that the resultant foamed body has
an unsatisfactory cell structure in respect of fineness and
uniformity.
The hydrocarbon or halogenated hydrocarbon compounds
suitable for use as a foaming agent in the compositions described
; herein are exemplified by propane, butane, isobutane, pentane,
neopentane, n-hexane, isohexane, n-heptane, methyl chloride,
methylene chloride, chloroform, carbon tetrachloride, ethylidene
chloride, ethylidene fluoride, trichloroethylene, 1,2-dichloro-
ethane, trichlorofluoromethane, dichlorodifluoromethane,
chlorotrifluoromethane, bromotrifluoromethane, tetrafluoro-
methane, dichlorofluoromethane, chlorodifluoromethane, trifluoro-
methane, trichlorotrifluoroethane, dichlorotetrafluoroethane,
dibromotetrafluoroethane, chloropentafluoroethane, hexafluoro-
L~
112Z3SO
ethane, l-chloro-l,l-difluoroethane and the like. These
volatilizable foamlng agents may be used in cornbination.
The extent of impregnation of the PVC resins with the
above mentioned volatilizable foaming agents depends on the
- desired degree of expansion into resin foams. Generally, the
degree of impregnation must be increased when a foamed body of
high expansion ratio is desired. When a foamed body of low
expansion is desired, 3~ by weight or less of a foaming agent
may sometir,les be sufficient. The amount of the foaming agent
is, however, in the range from 1 to 30% by weight or more in
most cases where foamed bodies of adequate expansion are to be
obtained.
The impregnation of the PVC resin with a volatilizable
foaming agent noted above is carried out in principle by
bringing these components into contact with each other.
Particularly, the PVC resin in a powdery form may merely be
blended with the foaming agent so that the foaming agent is
absorbed in the resin particles. When the foaming agent is
gaseous at room temperature and under atmospheric pressuré,
a convenient method for impregnation is to introduce the PVC
resin, water and dispersing agent into a pressurizable vessel,
e.g. an autoclave, equipped with a stirrer to forrn a suspension
of the resin powder in the aqueous medium and then the foaming
agent is introduced into the suspension with pressurization
followed by agitation of the mixture at temperatures of 30 to
90 C for 3 to 20 hours. After absorption equilibrium has been
established inside the vessel and the mixture is cooled to
room temperature, the resin having absorbed the foaming agent
is taken out of the vessel, dehydrated by a suitable means, such
as centrifugal separation, and dried under air flow at a
B
11223SO
relatively low temperature of, say, 50C or less to give the
desired PVC resin impregnated with the foaming agent.
The thus prepared resin composition impregnated with
the volatilizable foaming agent can be, as such, fabricated into
shaped resin foam articles by a conventional technique such as
injection molding, extrusion molding or compression molding in
a metal mold in which gelation of the resin and expansion of the
gelled resin by the gas produced by the vaporization of the
foaming agent take place simultaneously. It is optional that the
resin composition be, prior to fabrication, admixed with
additives conventionally used in the molding of PVC resins, such
as plasticizers, flame retardants, anti-oxidants, anti-static
agents and the like, at a relatively low temperature to prevent
premature vaporization of the foaming agent.
As mentioned earlier, one of the problems in obtaining
a foamed PVC resin body is to ensure fineness and uniformity
of the cell structure of the resin foam, especially, when the
ratio of expansion of the foam is extremely high or when the
foam has a bulk density of, for example, 0.10 g/cm3 or less.
Of course, depending on the manufacturing conditions, the foams
could have a bulk density of about 0~30 g/cm3. Improvement of
the cell structure of PVC resin foams is expected through the
use of foam conditioning agents. This invention discloses
certain types of thermoplastic resins as particularly effective
foam conditioning agents.
The foam-conditioning resins disclosed herein include
acrylic resins and styrene-based resins and these resins are
particularly effective when they have a reduced viscosity of at
least 3.0 dl/g as measured in a chloroform solution of 0.1 g/100
ml concentration at 25C. These foam-conditioning resins are
-- 8 --
'~
11223~0
blended with the PVC resin impregnated with the volatilizable
foaming agent in an amount of from 0.5 to 30 parts by weight per
100 parts by weight of the PVC resin impregnated with the
foaming agent before the resin composition is molded into shaped
resin articles.
An acrylic resin suitable as the foam-conditioning
resin is either a polymethyl methacrylate or a copolymeric resin
mainly composed of methyl methacrylate and one or more of
acrylic esters such as methyl acrylate, ethyl acrylate, n-butyl
acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, n-butyl
methacrylate, 2-ethylhexyl methacrylate and the like. The
content of methyl methacrylate in the acrylic resin is preferably
in the range from 60 to 95% by weight.
It is preferable that the acrylic resin, as the foam-
conditioning resin, have a reduced viscosity of at least 3.0 dl/g,
or, more preferably, at least 5.0 dl/g as measured in a
chloroform solution of 0.1 g/100 ml concentration at 25C.
It is preferable to use an acrylic resin with a higher
reduced viscosity or, in other words, having a higher average
degree of polymerization when the average degree of polymeriza-
tion of the PVC resin approximates the upper limit of 2,000.
Further, it is preferable to use an acrylic resin prepared by
the emulsion polymerization of the acrylic monomers. Additional
improvements are obtained by the use of such a resin, e.g., in
the smoothness of feeding into a molding machine, which reduces
the danger of blockage of the inlet for the resin composition
fed to the machine, in addition to the acceleration of uniform
gelation of the resin composition and increased expandability
of the gelled and molten resin composition.
The amount of the acrylic resin, as the foam-
.~'
l~Z~350
conditioning agent, to be admixed is from 0.5 to 30 parts by
weight or, preferably, from 3 to 20 parts by weight per 100 parts
by weight of the PVC resin impregnated with the foaming agent.
Larger amounts of the acrylic resin than noted above cannot
give any further improvement and, instead, undesirably effect
the properties inherent to PVC resins such as flame retardancy.
Styrene-based resins is the other class of foam-
conditioning resins. The styrene-based resin may be a homo-
polymer of styrene but it is preferably a copolymer mainly
composed of styrene with a minor amount of acrylonitrile as
the comonomer. It is, of course, optional that the copolymer
include one or more of other comonomers copolymerizable with
styrene and acrylonitrile. The styrene-based resin should have
a reduced viscosity of at least 3.0 dl/g as measured in a
chloroform solution of 0.10 g/100 ml concentration at 25 C. It
is preferable that the styrene-based resin have a reduced
viscosity as high as possible when the vinyl chloride-based
resin has an average degree of polymerization approximating the
upper limit of about 2,000.
The above mentioned comonomers copolymerizable with
styrene and acrylonitrile are exemplified by esters of acrylic
acid such as methyl acrylate, ethyl acrylate, n-butyl acrylate,
isobutyl acrylate, 2-ethylhexyl acrylate and the like; esters
of methacrylic acid such as methyl methacrylate, ethyl
methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate
and the like; maleic and fumaric acids and esters thereof and
maleic anhydride.
The above described styrene-based resins can be
prepared by a conventional method of polymerization but it is
preferable that the resins be prepared by emulsion polymerization
in an aqueous medium.
-- 10 --
~'
1~22350
The amount of the styrene-based resin to be used, as
the foam~conditioning agent, may be the same as with the acrylic
resins, i.e. in the range from 0.5 to 30 parts or, preferably,
from 3 to 20 parts by weight per 100 parts by weight of the
PVC resin impregnated with the volatilizable foaming agent.
The mechanism by which the improvement is obtained in
the cell structure of the resin foams by the addition of the
foam-conditioning resin is presumably that: the gelation of the
PVC resin is accelerated by the foam-conditioning resin and the
melt viscosity of the PVC resin in the molding step is adequately
controlled or increased so that the expandability of the foams
is enhanced and the cell walls of the foams are strengthened to
have a higher resistance against coalescence or collapse of the
foams as well as that the shrinkage of the once formed foams
at an elevated temperature is prevented with improved retention
of the gas produced by the vaporization of the foaming agent.
It was further discovered that the above described
foam-conditioning effect obtained by the addition of a foam-
conditioning resin is further enhanced when certain kinds of
nucleating agents are present in combination with the foam-
conditioning resin. One type of suitable nucleating agent is
a fine powdery inorganic material such as calcium carbonate,
talc, barium sulfate, fumed silica, titanium dioxide, clay,
aluminum oxide, bentonite, diatomaceous earth and the like
having an average particle diameter of 30 ~m or less, or
preferably, 10 ~m or less. Coarser particles of these inorganic
powders affect the fluidity of the molten resin in the molding
step adversely so that the surface condition of the foamed
bodies obtained with admixture of such coarser powders is
deficient in luster, sometimes, with striation and inferior
uniformity of the cell structure.
-- 11 --
1~223~0
Another class of suitable nucleating agents is the
product of the combination in about equivalent amounts of an acid
such as boric acid or organic acids, e.g. citric acid, tartaric
acid and oxalic acid and a carbonate or hydrogencarbonate of
sodium, potassium or ammonium such as sodium carbonate, sodium
hydrogencarbonate, potassium carbonate, ammonium hydrogencar-
bonate and the like.
The amount of the nucleating agent to be added in
combination with the foam-conditioning resin is in the range
from 0.01 to 20 parts by weight per 100 parts by weight of the
PVC resin impregnated with the foaming agent. When the amount
of the nucleating agent is in excess of 20 parts by weight, the
ratio of expansion of the foamed resin is decreased and the
resultant foamed body has inferior properties including less
smooth surfaces.
It is optional that the resin composition described
herein be admixed with a known decomposable foaming agent in so
far as the amount thereof is limited to, say 5 or less parts by
weight per 100 parts by weight of the PVC resin impregnated with
the volatilizable foaming agent. A suitable decomposable foaming
agent is exemplified by azo compounds such as azodicarbonamide,
azobisisobutyronitrile, diazoaminobenzene, diethylazodicar-
boxylate, diisopropylazodicarboxylate and the like; nitroso
compounds such as N,N'-dinitrosopentamethylene tetramine, N,N'-
dimethyl-N,N'-dinitroso terephthalamide and the like; and
sulfonylhydrazide compounds such as benzenesulfonylhydrazide,
toluenesulfonylhydrazide, 4,4'-oxy-bis(benzenesulfonylhydrazide),
3,3'-di(sulfonehydrazidephenyl)sulfone, toluenedisulfonyl-
hydrazone, thio-bis(benzenesulfonylhydrazide), toluenesulfonyl-
azide, toluenesulfonyl semicarbazide, 4,4'-oxy-bis(benzene-
sulfonylhydrazide) and the like; as well as sodium hydrogen-
- 12 -
3~;0
carbonate.
The use of these decomposable foaming agents isdesirable in order to further improve the fineness and uniformity
of the cell structure of the resin foams and to reduce the
shrinkage of the foamed body so that the shape of the foamed body
is better retained. However, the use of too much of a
decomposable foaming agent is undesirable due to the coloration
of the foamed body by the colored decomposition products thereof
and the roughened surface condition of the foamed body without
additional advantages. It is also preferable to add a
conventional decomposition promotor such as certain kinds of
zinc compounds, copper compounds and the like to accelerate
the decomposition of the decomposable foaming agent and enhance
gas evolution at a temperature lower than the molding temperature
of the resin composition.
The above described expandable resin compositions with
admixture of a foam-conditioning resin are advantageous for
manufacturing shaped bodies from PVC resin foams. The composi-
tions can give resin foams of high expansion with fine and
uniform cell structure regardless of the rigidity of the desired
foamed products, which can range from soft and flexible to hard
and rigid, by any one of conventional continuous fabrication
procedures including extrusion molding, injection molding,
compression molding and the like without any extra cost.
In the following, examples of the present invention
are given to ilLustrate the invention in further detail. In the
examples all parts are by weight. The methods for the deter-
mination of the degree of impregnation of the volatilizable
foaming agent in the PVC resin and the pore volume of the resin
are as follows.
~lZ23SC~
Amount of impregnation of the volatilizable foaming
àgent: the PVC resin impregnated with the volatilizable
foaming agent was heated in an air oven at 130C for 2 hours
and the amount of impregnation was calculated by the equation
(Wl - W2)/W2 x 100 (~), taking the weights before and after
heating as Wl and W2, respectively.
Pore volume of the PVC resin: the pore volume was
determined with a mercury-pressurizing porosimeter, Model 70
made by CARL ERBA Co., where the pressure of mercury was
increased from 1 to 100 kg/cm2 and expressed in ml per gram of
the resin.
EXAMPLE 1 (Experiments No. 1 to No. 13)
Into an autoclave of 5 liter capacity equipped with a
stirrer were introduced 1,000 g of a vinyl chloride homopolymer
or a copolymer resin composed of vinyl chloride and vinyl
acetate as indicated in Table 1, in which P and Vp stand for the
average degree of polymerization and the pore volume of the
resin, respectively, and 2,000 g of purified water; then 150 g of
trichlorofluoromethane and 200 g of butane were introduced
into the autoclave with pressurization followed by temperature
elevation with agitation up to 70C and continued agitation at
the same temperature for 8 hours to impregnate the resin with
trichlorofluoromethane and butane as the volatilizable foaming
agents.
After cooling to room temperature and discharging
the excess foaming agents out of the autoclave, the thus
impregnated resin was taken out of the autoclave, dehydrated
and dried under air flow at 40 to 50C for about 8 hours.
The degree of impregnation of the resin with the
- 14 -
~2Z35~
foaming agents was determined just after preparation and after
storage at 20C for 1 week to give the results set out in Table 1.
100 parts of the above obtained resin impregnated
with the foaming agents was blended with 2 parts of a tin-
containing stabilizing agent and 1 part of calcium stearate
and the resin blend was fabricated into a foamed cylindrical
rod by extrusion molding with an extruder machine operated with
the conditions given below.
The bulk density of the foamed rod obtained in each ~-
of the experiments was as given in Table 1.
Operating conditions of the extruder machine:
Screw diameter 20 mm
Screw length 400 mm
Screw compression ratio 3.0
Die 5 mm diameter opening
and 70 mm land length
Screens one with 80 mesh
opening and one with
100 mesh opening
Cylinder temperature Cl = 60 to 120C
C2 = 100 to 160C
C3 = 120 to 180C
Die temperature about 130 C
Revolutions 50 r.p.m.
The foamed rod obtained in Experiment No. 9 was very
fragile. Although the foamed rod obtained in Experiment No. 11
had a high ratio of expansion, it was inferior in flame
retardancy.
11223S~)
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-- 16 --
~'
~2Z3S~)
EXAMPLE 2 tExperiments No. 14 to No. 26)
Into the autoclave used in Example 1 were introduced
1,000 g of a copolymer resin composed of 88% by weight of vinyl
chloride and 12~ by weight of vinyl acetate, and having a pore
volume, Vp, of 0.010 ml/g and an average degree of polymerization
P, of about 650, 2,000 g of purified water and 1.0 g of a
partially saponified polyvinyl alcohol; and then one or two
volatilizable foaming agent(s) as indicated in Table 2 in
amounts also as indicated in Table 2 were introduced into the
autoclave, if necessary, with pressurization followed by
agitation for 8 hours at 70C to impregnate the resins with the
foaming agent(s).
The notations for the volatilizable foaming agent(s)
used in this Example are as follows and will hereafter be used in
other examples.
PR: propane
PE: pentane
HE: n-hexane
TCFM: trichlorofluoromethane
MC: methyl chloride
BU; butane
MEC: methylene chloride
DCTFE: dichlorotetrafluoroethane
DCDFM: dichlorodifluoromethane
DCFM: dichlorofluoromethane
TCE: 1,1,2-trichloroethane
TCDFE: tetrachlorodifluoroethane
ISO: isooctane
The degree of impregnation with the foaming agent(s)
and the bulk density of the foamed cylindrical rods, fabricated
~llZZ350
in the same manner as in Example 1, were as set out in Table 2.
The foamed rods in Experiments Nos. 24 to 26 exhibited large
shrin~age after molding.
- 18 -
1~22350
1-' I
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'~ O ~: ô ,, a)
n + LL, U~. O
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. ~ ~1 O
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~0 ~0 ~ ~
~~ O ~ O ~ O
+ ~ ~ O
~_ ~_ ~ O
1 _ _ ~ ~
_ ~
O O ~ 0
~1~4 01L1 0 . O
+ ~ ~ 0 ~
~_ _ ~ O
_ ~
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O ~0 ~0 ~ O
m ~ + ,, ~ o
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a ~ o .
,,m r~ o .
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a~~ O ~ o . ,,
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- 19 -
- EP
112Z3SO
EXAMPLE 3 (Experiments No. 27 to No. 33)
Into a 100 liter capacity autoclave made of stainless
steel and equipped with a stirrer were introduced 30 kg of
the vinyl chloride and vinyl acetate copolymer resin used in
Example 2, 50 kg of purified water and 15 g of a partially
saponified polyvinyl alcohol; and further a mixed foaming agent
composed of butane and trichlorofluoromethane in a 2:1 ratio
was introduced with pressurization into the autoclave in an
amount as indicated in Table 3, followed by agitation for 8
hours at a temperature also as indicated in Table 3 to impregnate
the resin with the foaming agent. The dehydration and drying of
the resin impregnated with the foaming agent were undertaken
in the same manner as in Example 1. The degree of impregnation
with the foaming agent was as set out in Table 3.
Resin blends were prepared each with 100 parts of the
above obtained resin impregnated with the foaming agent, 2 parts
of a tin-containing stabilizing agent and 1 part of calcium
stearate and the resin blend was fabricated into a foamed body
in the form of a slab by extrusion molding with an extruder
machine operated with the conditions as given below.
The bulk density, heat conductivity, as measured at
20C according to the method specified in JIS A 1413, and
compression strength, as measured at 20C according to the
method specified in ASTM D 1621, of the foamed slabs were
determined to give the results sèt out in Table 3.
Operating conditions of the extruder machine:
Screw diameter 65 mm
Screw length 1,300 mm
Screw compression ratio 2.0
- 20 -
Z3S~
Die 100 mm width and 8 mm
height
Screens one with 80 mesh
opening and
one with 100 mesh
opening
Cylinder temperature Cl = 80C
C2 = 120C
C3 = 150C
Die temperature 120 C
Revolutions 30 r.p.m.
- 21 -
.~`' '.
~lZZ3~
_ _
~ ~. o a) o o o
._ ._ ,., .... ,.......... ....... ., .
~ ~o oo o ~o ~ 0
__ _ , ~ . . _... .. .....
~_ ~D ~ . O O
o~ o o o~
o _ . . _._ __ .. .. .. .. . .
~ .- C- ~ O O ~D
~ _ _ . __. .. .. .
~ ~ a: o ~i o o
I . . . .. . _
I CO ~ ~ ~ o o ~
_, _ ~ _O_~ O _ ,__~,
o o o o' o
. _ _.. c,_.. .~
o g
~) ~ ~ ~ .,.~ .
. o ~ ~ ~ b~
O b~ .,1 ~ ~ ~ ~
b4 ~ m ~1 ~ +' ~ ~ a) ~,
.~ a) O s~ ~1 ~ E; ~a o ~ 6 h ~
6 h ,1-~1~ 3 a) a~ 3 o O ~ bO
~ ~0 'a ~: ~ ~ ~ ~ ~ ~ 3~ ~Y
6 ~ ~ S~ &~ h O
~ ~ ~ a~ ~ ~ a~
a~ ~ ~ ~ D ~ U~ 6
~ o X ~ ~ ~+~ o
X E~ 0 a~ 6 ,~ bo a~ h ,~ o ~
r~ c~ 6 ~ ~ H 3 la 3 ....
-- 22 --
E~7
~LlZ23~i0
EXAMPLE 4 (Experiments No. 34 to No. 43)
The proceduxe of Example 1 for the preparation of a
vinyl chloride and vinyl acetate copolymer resin impregnated with
a mixed foaming agent of trich~orofluoromethane and butane was
repeated; where the resin used had a vinyl acetate content,
average degree of polymerization, P, and pore volume, Vp, as
indicated in Table 4. The degree of impregnation with the
foaming agent as determined just after preparation and after
storage for 1 week at 20C were as set out in Table 4.
Expandable resin compositions were prepared each by
blending 100 parts of the above prepared copolymer resin
irnpregnated with the ~ixed foaming agent, 2 parts of a tin-
containing staiblizing agent and 1 part of calcium stearate
along with or without the addition of 1 part of talc, as the
nucleating agent, 1 part of an azodicarbonamide compound,
CELMIC 133 a trade mark of Sankyo Kasei Co., Japan, as a
decomposable foaming agent, and either one of the acrylic
resins E-l and E-2 as defined below in an amount given in Table 4.
The acrylic resins used as the foam-conditioning
agent in the experiments and designated as E-l or E-2 in
Table 4 were the following products, respectively:
E-l: a copolymeric resin composed of 90% by weight
of methyl methacrylate and 10% by weight of
ethyl acrylate and having a reduced viscosity
of 10 dl/g at 25C in a 0.1 g/100 ml chloroform
solution, and
E-2: an acrylic resin commercially available under
the trade mark PARALOID K-120 from Rohm & Haas
Co .
- 23 -
~"7
l~ZZ35~J
The expandable resin compositions were fabricated
into foamed rods by extrusion molding with theJex~ruder machine
and operating conditions used in Example l; and the foamed rods
were examined for bulk density and cell structure to give the
results as set out in Table 4. The evaluation of the cell
structure given in Table 4 was determined according to the
following standards.
Cell structure A: cell diameter not exceeding 500 ~m
Cell structure B: cell diameter from 500 ~m to 2,000~m
The foamed rod obtained in Experiment No. 40 was
fragile. In Experiment No. 43 premature expansion of the resin
composition took place while still in the die leading to the
appearance of flow marks on the surface of the foamed rod.
- 24 -
B?
350
Table 4
Experiment No. 34 35 36 37 38
Content of vinyl
acetate, % by12 12 5 20 30
PVC weight
resin
p 520 520 350 700 1000
Vp, ml/g 0.010 0.010 0.009 0.0120.020
Impre~ nation As 11 0 11 0 8.0 10.3 7.5
with mixed prepared . .
foaming
weight Alt r 10.3 10.3 7.4 9.7 7.0
Nucleating agent Yes Yes Yes Yes Yes
Decomposable No Yes Yes Yes Yes
foaming agent
Acrylic resin E-1 E-1 E-2 E-2 E-2
(parts) (10.0) (10.0) (6.0) (6.0) (6.0)
:
t~e~ o density,0.05C 0.045 0.05C 0.051 u.10
. structure A A A A A
Cont'd.
~2Z350
Table 4 Cont'd.
3940 41 42 43
4010 30 2 45
1300270 1600 800 810
0;023 0.'010 0.050 0.060 0.020
7. 9.0 6.0 6.99 5
6.6 8.0 4.0 5.48.5
Yes No No No Yes
Yes No No No No
E-2 None None None None
0 20 0.~4 0.30 0.23 0.11
A B B B B
D
- 26 -
2350
EXAMPLE 5 (Experiments No. 44 to No. 54)
Into the autoclave used in Example 1 were introduced
1,000 g of the vinyl chloride and vinyl acetate copolymer resin
used in Example 2, 2,000 g of purified water and 1.0 g of a
partially saponified polyvinyl alcohol; and then one or two
volatilizable foaming agents as indicated in Table 5 and in
amounts also as indicated in Table 5 was introduced into the
autoclave with pressurization followed by agitation at 70C
for 8 hours to impregnate the resin with the foaming agent(s).
The degree of impregnation with the foaming agent(s) was as set
out in Table 5.
Expandable resin compositions were prepared each by
blending 100 parts of the copolymer resins impregnated with
the volatilizable foaming agent(s), 1 part (Experiments No. 44 to
No. 46) or 3 parts (Experiments No. 47 to No. 54) of a nucleating
agent as indicated in Table 5 along with or without the addition
of 6 parts of an acrylic resin (METABLEN P551, a trade mark of
Mitsubishi Rayon Co., Japan) as the foam-conditioning agent.
The nucleating agents used in the experiments were as
follows.
ORBEN: a trade mark of Shiraishi Calcium Co., Japan for an
organic complex of a colloidal hydrated aluminum
silicate having an average particle diameter of about
0,5 ~m;
HAKUENKA O: a trade mark of Shiraishi Calcium Co., Japan for a
calcium carbonate filler having an average particle
diameter of 0.02 to 0.03 ~m;
Titanium Dioxide A-100: a filler grade titanium dioxide havlng
an average particle diameter of about 0.15 to 0.25 ~m,
a product of Ishihara Sangyo Co., Japan;
- 27 -
B~
Z3~0
AEROSIL 200: a trade mark of Nippon Aerosil Co., Japan for a
fumed silica filler having a specific surface area
of about 200 m2/g and an average particle diameter
of about 0.012 ~m;
AEROSIL 380: a trade mark of Nippon Aerosil Co., Japan for
a fumed silica filler having a specific surface
area of about 380 m2/g and an average particle
diameter of about 0.002 ~m;
A12O3C: an alumina filler having an average particle diameter
of about 0.005 to 0.02 ~m, a product of Nippon
Aerosil Co., Japan;
Barium Sulfate #100: a product of Sakai Chemical Co., Japan,
having an average particle diameter of about 0.6 ~m;
SATENTON No. 5: a trade mark of Tsuchiya Kaolin Co., Japan
for a clay product;
3S Talc: a talc product of Nitto Funka Kogyo Co., Japan.
The expandable resin compositions thus prepared were
fabricated into foamed bodies in the form of a cylindrical
rod by extrusion molding with the extruder machine and the
operating conditions used in Example 4; and the foamed rods
were examined for their bulk density to give the results as set
out in Table 5.
- 28 -
B`
~223~0
Table 5
Experiment No. 1 44 45 46 . 4~8
Volatilizable PR PE TCFM BU BU
foaming (300) (300) (300)(300) (200)
agent (g) MEC
. . _
Impregnation with
foaming agent, 6.5 7.0 15.4 7.3 11.0
% by weight
Nucleating ORBEN ORBEN HAKU- Titanium A~ROSIL
agent ENKA A-100 200
.
Decomposable No No No No No
foaming agent
. _ ._
Acrylic resin Yes Yes Yes Yes Yes :~ -
foamed rod, g/ml0.0890.093 0 077 0.080 0.039
Cont'd.
- 29 -
B`;
~l~Z350
Table 5 Cont ' d .
I l I
49 50 51 52 53 54
TCFM TCFM TCFM TCFM TCDFE IS0
( 200 ) ( 30 ) ( 100 ) ( 200 ) ( 200 ) ( 200 )
PE BU BU BU
( 1 00 ) ( 3 ) ( 100 ) ( 400 )
. .__ . . . ,
12.4 3.4 8.2 15.0 9.8 7.4
. . .__ .
2 Barium Talc Clay AEROS I I HAKU-
3 Sulfate 380 ENKA O
# 100 .. .. __ -, ~
Yes Yes Yes Yes Yes Yes .
Yes Yes Yes Yes No No
. .
59_ _ 0 . 15 0 . 073 0. 030 0 . 70 0 . 81 .
B -30_
~Z2350
EXAMPLE 6 (Experiments No. 55 to No. 68)
Into a 100 liter capacity autoclave made of stainless
steel and equipped with a stirrer were introduced 30 kg of
a copolymer resin composed of 884 by weight of vinyl chloride
and 12~ by weight of vinyl acetate and having an average degree
of polymerization, P, of about 850 and a pore volume, Vp, of
0.015 ml/g, 50 kg of purified water and 15 g of a partially
saponified polyvinyl alcohol; and then 6 kg of trichlorofluoro-
methane and 3 kg of butane were introduced with pressurization
into the autoclave followed by agitation at 70C for 8 hours to
impregnate the resin with trichlorofluoromethane and butane as
the volatilizable foaming agents. After completion of impregna-
tion, cooling to room temperature and discharging of excess
foaming agents, the resin was dehydrated by centrifugal
separation and dried under air flow at 40 to 50C. The total
amount of foaming agents in the resin was 11.84 by weight.
Expandable resin compositions were prepared each by
blending 100 parts of the above obtained copolymer resin
impregnated with the volatilizable foaming agents, 2 parts of a
tin-containing stabilizing agent and 1 part of calcium stearate
along with or without the addition of talc (Experiments other
than No. 59) in an amount indicated in Table 6, or a combination
of 0.5 part of sodium hydrogencarbonate and 0.4 part of citric
acid (Experiment No. 59) as a nucleating agent, a decomposable
foaming agent and an acrylic resin as a foam-conditioning agent
as given in Table 6.
The notations used in Table 6 for the decomposable
foaming agents and the acrylic resins are as follows:
AIBN: ~ azobisisobutyronitrile,
PTS: p-toluenesulfonyl hydrazide,
- 31 -
l~ZZ350
OBS: 4,4'-oxy-bis(benzenesulfonyl hydrazide),
DNM: dinitrosopentamethylenetetramine, and
CETMIC 133: see Example 4;
E-3: a copolymer resin composed of 80% by weight of
methyl methacrylate, 10% by weight of butyl
acrylate and 10% by weight of ethyl acrylate
having a reduced viscosity of 5.5 dl/g at 25C,
E-4: a copolymer resin composed of 85~ by weight of
methyl methacrylate and 15% by weight of butyl
acrylate having a reduced viscosity of 5.0 dl/g
at 25C,
E-5: an acrylic resin commercially available under
the trade mark of PARALOID K-125 from Rohm & Haas
Co., and
E-6: an acrylic resin commercially available under
the trade mark of PARALOID K-125 from Rohm &
~aas Co.
Each of the resin compositions was fabricated into a
foamed body in the form of a slab by extrusion molding with
2~ the extruder machine and the operating conditions used in
Example 3; and the foamed slabs were examined for their bulk
density, cell structure, appearance, compression strength,
other mechanical properties and heat conductivity. The
determination of the compression strength was carried out in
accordance with the method specified in ASTM D 1621 and the heat
conductivity was determined in accordance with the method
specified in JIS A 1413. The results are set out in Table 6.
In Experiments No. 67 and No. 68, premature expansion
of the resin compositions took place while still in the die
leading to broken foams and appearance of flow marks on the
- 32 -
`1
~lZ2350
surface of the foamed slabs. The appearance of the foamed slab
obtained in Experiment No. 66 was also less satisfactory. The
cell structure of the foamed slabs was satisfactory in all of
the experiments except that the foamed slab in Experiment No. 65
exhibited less uniformity in its cell structure.
~.,
llZZ35~
Table 6
Experiment No. 55 56 57 58 59
agent, parts 1.0 1.0 1.0 1.0 (Steeet)
Decomposable AIBN PTS OBS DNM CEL~IC
foaming agent (1.0) (1.0) (1.0) (1.0) 133
(parts) + (1.0)
Urea
(1.0)
Acrylic resin E-3 META- E-4 E-5 E-5
(parts) (5.0) BLEN (5.0) (1.0) (20)
; P 501
(5.)
Bulk .
g/ml 0.034 0.0350.035 0.030 0.033
~ ..
compression
PirepseOrf kg/cm~ 3.3 3.5 3.5 3.0 3.4
folaabed strength,5.1 5.4 5.4 4.8 5.3
Tensile
kg/cm~ 5.0 5.2 5.3 4.8 5.1
Heat con-
ductivity,0.025 0.0260.026 0.025 0.028
kcal/m.hr.~C .
Cont'd.
- 34 -
B~
112Z350
Table 6 Cont'd.
60 61 62 63 64 65 66 67 68
l.0 0.02 15 1.0 1.0 0.005 30 1.0 1.0
AIBN None None ELMIC CELMIC None None CELMIC CELMIC
(1.0) (335) (330) (330) 1330)
E-5 E-5 E-5 E-6 E-6 E-3 E-3 E-3 E_3
(30) (10) (25) (10) (10) (5.0) (5.o)(5.0 (0.3)
0.035 0.034 0.040 0.033 0.045 0.070 0.059o.oao o .095
.
3.8 3.6 4.8 3.3 5.0 7.3 6.0 7.3 12.4
6.7 6.5 7.8 5.5 8.1 10.3 8.8 13.0 20.l
5.5 5.4 7.0 5.3 7.8 10.5 9.0 16.8 21.3
.
0.028 0.027 0.029 0.028 0.031 0.037 0.035 0.038 0.043
B` - 35 _
~lZZ3~(~
EXAMPLE 7 (Experiments No. 69 to No. 89)
Into an autoclave of 5 liter capacity made of
stainless steel and equipped with a stirrer were introduced
1,000 g of a homopolymeric polyvinyl chloride resin or a
copolymer resin composed of vinyl chloride and vinyl acetate as
indicated in Table 7, 2,000 g of purified water, and one or
two volatilizable foaming agents as indicated in Table 7 in
amounts also as given in Table 7 with, if necessary,
pressurization followed by agitation at 70C for 8 hours to
impregnate the resins with the volatilizable foaming agent(s).
After completion of impregnation, cooling to room temperature
and discharging of excess foaming agent(s), the resins were
dehydrated by filtration and dried under air flow at 40 to 50C
for about 5 hours. The resins thus obtained were examined for
the amount of foaming agent(s) contained therein to give the
results as set out in Table 7. Further, the resins were kept at
20C for 1 week to examine the foaming agent(s) loss by
dissipation during storage. The decrease in the amount of
foaming agent(s) ranged from 6 to 9~ for each of the resins.
Expandable resin compositions were prepared each by
blending 100 parts of the above obtained resins impregnated
with the volatilizable foaming agent(s), 2 parts of a tin-
containing stabilizing agent and 1 part of calcium stearate
along with or without the addition of a nucleating agent, a
decomposable foaming agent and an acrylic resin (E-l) as the
foam-conditioning agent as indicated in Table 7. The resin
compositions were each fabricated into a foamed body in the form
of a cylindrical rod by extrusion molding. The operating
conditions of the extruder machine were as follows:
- 36 -
~'
23~0
Operating conditions of the extruder machine:
Screw diameter 25 mm
Screw length 750 mm
Screw compression ratio 3.0
Die 8 mm diarneter opening
and
100 mm land length
Screens one with 80 mesh
opening and
one with 100 mesh
opening
Cylinder temperature Cl = 60 to 120C
C2 = 100 to 160C
C3 = 120 to 180C
Die temperature 100 to 130 C
Revolutions 50 r.p.m.
The thus obtained foamed rods were examined for bulk
density and the condition of their cell structure to give the
results as set out in Table 7.
The cell structure C indicates that the foam cells
had a diameter exceeding 1 mm and the structure was coarse and
not uniform. I
The foamed rod obtained in Experiment No. 84 was
fragile and the foamed rods obtained in Experiments No. 88 and
No. 89 exhibited shrinkage after molding.
.,
~2Z350
Table 7
_ I . .... .__
Experiment No. 69 70 71 72 73 74
. . .
Content of
vinyl acetate, 5 10 0 10 10 10
% by weight
PVC ____ .
resin P 400 750 750 1000 1000 1000
Vp, ml/g 0.011 0.013 0.060 0.025 0.025 0.025
Volatilizable TCFM TCFM TCFM TCFM TCFM TCFM
foaming agent (150) (150)(150) (150) (150) (150)
used (g) + + + + + +
BU BU BU BU BU BU
(100) (100)(100) (100) (100) (100)
.
Impregnation with
foaming agent, % by 11.0 10.8 7.8 9.7 9.7 9.7
weight
. __ . .
Nucleating Talc Talc Talc HAKU- oRsE~ Talc
agent (parts) (1.0) (1.0) (1.0) ENKA (5) (0.5)
(parts~ None C(330) (OT03(OB5N)(0 5) (2)
i '''' -~ ~~~~~--I 1 ~ I 1 0 ~
~roper- Bulk
ties of density, 0.065 0.045 0.0600.054 0.052 0.053
foamed g/ml
rod . .
_ ~ structure A A A A A A
) Sodium hydrogerlcarbonate
Cont'd.
B - 38 -
1122~0
Table 7 Cont'd.
76 77 78 79 80 81 1 92 83
1010 10 10 10
10001700 850 850 850850 850 850 850
. .
0.025 0.029 0.015 0.015 0.015 0.015 0.015 0.015 0.015
TCFM TCFM PR BU PE TCFM TCFM TCFM TCFM
(l~0) (150) (300) (3) (30) (3) (3) (100) (200)
BU BU BU BU BU
(100) (100) (300) (100) (400)
9.7 9.3 6.5 7.5 8.3 15.6 3.4 8.6 15.0
Talc Talc Talc Talc Talc Talc Talc Talc Talc
(0.05) (1.0) (0.5) (0.5) (1.0) (1.0) (1.0) (1.0) (1.0)
~_
SHC None None None CELMIC CELMIC CELMI CELMIC CELMIC
(5)133 133 133 133 133
(2.0) (0.5) (~.5) (0.5) (0.5)
~0 5 5 5 5 5
0.0460.0680.0800.071 0.0850.0580.0900.069 0.045
.... .
A A A A A A A A A
Cont'd.
39 -
~122350
Table 7 Cont'd.
_ 85 86 ¦ ~7 8~ ¦ ag
lo 10 1'-
290 ~00 1700 2100 850 850
0.0l5 0.030 0.25 0.12 0.015 ~.015
TCFM TCFM TCFM TCFM TCDFE IS0
(150) (150) (150) (150) (200) (200)
BU BU BU BU
(200) (200) (200) (200)
9.0 7.8 2.7 3.5 10.3 7.6
I Talc Talc None None Talc Talc
(.1 ) ( I .0) (1 .) (1 )
None None AIBN None CE~MIC CELMI
(1.0) (335) (335)
O O O 10 O O
0 . 1 5 ~ i 1 . 1 1 . 1 0 . 78 0 . 93
-- 40 --
11~2~0
EXAMPLE 8 (Experiments No 90 to No. 103)
.
Into an autoclave of 100 liter capacity made of
stainless steel and e~uipped with a stirrer were introduced 30 kg
of a copolymer resin composed of 90% by weight of vinyl chloride
and 10% by weight of vinyl acetate and having an average degree
of polymerization of 1,050 and a pore volume of 0.023 ml/g, 50 kg
of purified water and 15 g of a partially saponified polyvinyl
alcohol; and then 6 kg of trichlorofluoromethane and 3 kg of
butane were introduced into the autoclave with pressurization
followed by agitation at 70C for 8 hours to impregnate the
resin with trichlorofluoromethane and butane as the volatilizable
foaming agents. After completion of impregnation, cooling to
room temperature and discharging of excess foarning agents, the
resin was dehydrated by centrifugal separation and dried under
air flow at 40 to 50C. The total amount of trichlorofluoro-
methane and butane in the thus impregnated resin was 12.0% by
weight.
Expandable resin compositions were prepared each by
blending 100 parts of the above prepared resin impregnated with
the volatilizable foaming agents, 2 parts of a tin-containing
stabilizing agent and 1 part of calcium stearate along with or
without the addition of 1 part of talc as the nucleating agent,
0.5 part of CELMIC 133 as the decomposable foaming agent and
one of the acrylic resins E-7 to E-13 in an amount as indicated
in Table 8. The resin compositions were fabricated into
foamed bodies in the form of a slab by use of an extruder
machine operated with the conditions as given below:
The nucleating agent was omitted in Experiments No. 100
and No. 101 and the decomposable foaming agent was omitted
30 in Experiments No. 100 and No. 102.
`F$
~1223SO
Acrylic resins:
E-7: a copolymer resin composed of 90% by weight of
methyl methacrylate and 10% by weight of ethyl
acrylate and having a reduced viscosity of 4.5
dl/g at 25 C,
E-8: a copolymer resin composed of 90% by weight of
methyl methacrylate and 10% by weight of ethyl
acrylate and having a reduced viscosity of 7.0
dl/g at 25C,
E-9: a copolymer resin composed of 90% by weig-ht of
methyl methaerylate and 10% by weight of ethyl
acrylate and having a reduced viscosity of 11.0
dl/g at 25C,
E-10: a copolymer resin eomposed of 90% by weight of
methyl methaerylate and 10% by weight of ethyl
aerylate and having a redueed viseosity of 15.3
dl/g at 25C,
E-ll: a eopolymer resin eomposed of 95% by weight of
methyl methacrylate and 5% by weight of butyl
aerylate and having a redueed viseosity of 10.7
dl/g at 25C,
E-12: a copolymer resin eomposed of 80% by weight of
methyl methaerylate, 5% by weight of ethyl
aerylate, 5% by weight of butyl aerylate and
10% by weight of butyl methacrylate and having
a reduced viseosity of 11.0 dl/g at 25C, and
E-13: a eopolymer resin composed of 80% by weight of
methyl methaerylate and 20% by weight of ethyl
acrylate and having a reduced viscosity of 2.0
dl/g at 25 C.
~ - 42 -
~Z;2 3SO
Operating conditions of the extruder machine:
Screw diameter 65 mm
Screw length 1,950 mm
Screw compression ratio 3.0
Die 100 mm width and
8 mm height
Screens one with ao mesh
opening and
one with 100 mesh
opening
Cylinder temperature Cl = 95 C
C2 = 130C
C3 = 150C
Die temperature 120C
Revolutions 20 r.p.m.
The thus obtained foamed slabs were examined for bulk
density, cell structure, compression strength as determined by
the method specified in ASTM D 1621 and flexural strength as
determined by the method specified in ISO R 1209 to give the
results set out in Table 8.
In Experiments No. 98 and No. 99, premature expansion
of the resin compositions took place while still in the die
leading to broken foams and shrinkage of the foamed slabs after
molding, with less uniform cell structure. The foamed slabs
obtained in Experiments No. 102 and No. 103 were also less
uniform in their cell structure although no premature expansion
of the resin compositions took place.
The results given in Table 8 show that an acrylic resin
with an increased reduced viscosity can give the advantages of:
the possibility of reducing the amount of the acrylic resin
required, increased gas retention for forming the foams,
stabilization of the foam cells and a decrease in the shrinkage
;~
23~0
of the foams. On the other hand, when the acrylic resin used
has a low reduced viscosity or the amount of the acrylic resin
is insufficient, the resultant foams break, shrink after
molding and have a coarser cell structure.
- 44 -
~11223~0
Table 8
Experiment No. gn 9l 92 93 94 95
A~rylic resin E-7 (E68) (5)E-11 (6)2E(23o
.
; Bulk 0.048 0.048 0.043 0.050 0.049 0.067
Proper-!cell A A A A A A
tieS Of~S~trUcture
foamed I Compression
slab~stren/gth2, 3.4 3.43.o 4.5 4.4 6.3
!
Flexural
strength, 5.7 5.65.0 6.3 6.0 9.3
¦ kg/cm2
Cont'd.
Table 8 Cont'd.
96 97 98 99 100 lOl l02 l03
E-10E-10 E-10 E-13 E-7 E-7 NoneNone
(5)(25) (0.3) (5) (10)(10)
0.0~2 0.0500.23 0.250.12 0.095 0.16 0.-l5
A A B B 3 B C C
3.03.6 21.0 22.3 _ _ _
5.l6.5 29.3 30.4 _ _ _ _
.~'
- 45 -
~1223~0
EXAMPLE 9 (Experiments No. 104 to No. 111)
Into an autoclave of 10 liter capacity made of
stainless steel and equipped with a stirrer were introduced 3 kg
of a homopolymerlc polyvinyl chloride resin or vinyl chloride
and vinyl acetate copolymer resins whereinthe vinyl acetate resin
content is given in Table 9,having an average degree of
polymerization and a pore volume as indicated in Table 9, 5 kg
of purified water and 1.5 g of a partially saponified polyvinyl
alcohol; and then 600 g of trichlorofluoromethane and 300 g of
butane were introduced into the autoclave with pressurization
followed by agitation at 70C for 8 hours to impregnate the
resins with trichlorofluoromethane and butane as the
volatilizable foaming agents. After completion of impregnation,
cooling to room temperature and discharging of excess foaming
agents, the resins were dehydrated by filtration and dried under
air flow at 40 to 50C for 5 hours. The total amount of the
foaming agents in the thus impregnated resins were as set out
in Table 9.
Expandable resin compositions were prepared each by
blending 100 parts of the above obtained resins impregnated
with the volatilizable foaming agents, 2 parts of a tin-
containing stabilizing agent, 1 part of calcium stearate, 1 part
of talc as a nucleating agent and 10 parts of one of the acrylic
resins E-7, E-10 or E-13 as a foam-conditioning agent. The
resin compositions were fabricated into foamed bodies in the
form of a cylindrical rod in the same manner as in Example 7.
The bulk density and the cell structure of these foamed rods
were as set out in Table 9. The foamed rods obtained in
Experiments No. 109 and No. 110 exhibited slight shrinkage
after molding.
- 46 -
B`
llZ23~
The results given in Table 9 show that when the vinyl
chloride-based resin has an increased degree of polymerization,
the use of an acrylic resin with a correspondingly increased
reduced viscosity is preferable; and foamed rods of high
expansion with uniform cell strueture can be obtained from a
resin with a relatively redueed eontent of vinyl aeetate, whieh
otherwise requires a relatively high fabrieation temperature,
by suitable selection of the aerylie resin used as the foam-
eonditioning agent.
- 47 -
~`'
.~
1~223SO
I o o~ ~,_
~ O u~ r-~ ~ O ~
,~ a: o ~ o m
_
C C~
~ o ~ ~o
~1 O 0 O I r O c~
O O
_ g r-~ ,_ .
o ~ ~ ~ ~0 0
r- O
O ~_~ O
_
O O ~ _~ O
~ ~ r- t O
~ _ O ~ O
l_ O 0 O O
O O Ir~ 1~ r- _ ~O
~ a~ o ~ o o c
_ O r O
_ - o ~ 1 O-` ~D ~
a~ o O O O I r O ¢
1) ~ O ~ O
D _
(~ U~ O C\J O o U~
0~ O ~ O
~_ _ O
r- o _~ ao
o u~ 8 O r- O O
~ O ~ O'
r . _
_ h
.,, ,~ ~
a) J ~~ 1~ ~i u~ ~ ~1 3
+~ ~ ~ 0 ~ ~1 ~: ~ ~ h
~ ~ a~ ,n .,, ~h--- ~ a~ ~
a~ o ~ O ~ P~u~ m ~ b~ ~
'~:~ ~O~`o ~ ~ ~ ~
I . o ~ ~ .
B
-- 48 --
1122350
EXAMPLE 10 (Experiments No. 112 to No. 125)
Into an autoclave of 5 liter capacity made of
stainless steel and equipped with a stirrer were introduced 1,000
g of a homopolymeric polyvinyl chloride resin or a copolymer
resin of vinyl chloride and vinyl acetate, wherein the vinyl
acetate content, average degree of polymerization and pore
volume are indicated in Table 10, 2,000 g of purified water and
1.0 g of a partially saponified polyvinyl alcohol; and then
150 g of trichlorofluoromethane and 100 g of butane were
introduced into the autoclave with pressurization followed by
agitation at 70C for 8 hours to impregnate the resins with
trichlorofluoromethane and butane as the volatilizable foaming
agents. After completion of impregnation, cooling to room
temperature and discharging of excess foaming agents, the resins
were dehydrated by filtration and dried under air flow at 40 to
50C for about 5 hours.
The total amount of the foaming agents in the resins
impregnated therewith were determined to give the results as
set out in Table 10. The loss of the foaming agents by
dissipation during storage at 20C for 1 week ranged from
6 to 9% for each of the resins.
Expandable resin compositions were prepared each by
blending 100 parts of the above obtained resins impregnated with
foaming agents, 2 parts of a tin-containing stabilizing agent
and 1 part of calcium stearate along with or without the
addition of a nucleating agent of the type and in an amount
indicated in Table 10, a decomposable foaming agent also as given
in Table 10 and a copolymer resin S-l composed of 70~ by weight
of styrene and 30% by weight of acrylonitrile and having a
reduced viscosity of 12.0 dl/g at 25C as a styrene-based
- 49 -
iB
1~22350
foam-conditioning resin in an amount indicated in Table 10.
The resin compositions were fabricated into foamed bodies in the
form of a cylindrical rod by extrusion molding. The operating
conditions of the extruder machine were substantially the same
as in Example 7.
The thus obtained foamed rods were examined for bulk
density and cell structure to give the results as set out in
Table 10.
~-? - 50 -
3;:~
Table 10
Experiment No. 112 113 11~ 115 116 117
Content of
vinyl acetate, 5 10 0 10 10 10
PVC Y ~ g~ _ . . .. ._................... .
resin 400 750 750 10001000 1000
Vp, ml/g0.011 0.013 0.060 0.025 0.025 0.025
Impre ~gnation with
volatilizable foaming 11.0 10.8 7.8 9.7 9.7 9.7
agent, % by weight
Nucleatin~ agent Talc Talc Talc Talc Talc ORBEN
(parts~ (2.0) (1.0) (1.0) (0.03) (0.5) (5)
Decomposable None CEL~IIC None SHC CELMIC AIBN
foaming agent 133 (4.0) 133 (0.5)
(parts) (1.0) (1.5)
Styrene-based 6.06.0 10.08.0 8.0 8.0
resin (S-1),
parts
Proper-- Bulk
ti es o f density, 0.060 0.044 0.061 0.049 0.050 0.055
foamed g/ml
rod Cell
structure A A A A A A
Cont'd.
- 51 -
:L1223~;i0
Table lO Cont'~.
3 - r---0-- l21 1Z~ 123 1Z4 -
lo ~ 10 10 10 ~ 10 ~1
lO00 1700 11000 1000 1000 1700 2100 1800
_ .
0.025 0.02~ 0.030 0.030 0.030 0.25 0.21 0.025
. ....................................... ,
9.7 9.3 9.4 9.4 9.4 2.7 3.5 6.0
_ l
HAKU- Talc Talc None None None None Talc
ENKA (1.0) (~ 0) _ ¦ - (1 0)
( 3) None None AIBN None None None None
¦ 8.0 lO.0 None None 8 None 8 None
. _ .
jo.o60 0.069 0,Z0 ~ 0.20 1.1 ~.1 0.30
; A A C ~ ~ C C B
B 52
23S~
EXAMPLE 11 (Experiments No. 126 to No. 135)
Into an autoclave of 5 liter capacity made of stainless
steel and equipped with a stirrer were introduced 1,000 g of
a copolymer resin composed of 90% by weight of vinyl chloride
and 10% by weight of vinyl acetate and having an average degree
of polymerization of 850 and a pore volume of 0.015 ml/g, 2,000
g of purified water and 1.0 g of a partially saponified
polyvinyl alcohol; and then one or two kinds of volatilizable
foaming agent(s) as indicated in Table 11, was added or
introduced with pressurization into the autoclave followed by
agitation at 70 C for 8 hours to impregnate the resin with the
foaming agent(s).
After completion of impregnation, cooling to room
temperature and discharging of excess foaming agent(s), the
resins were dehydrated by centrifugal separation and dried
under air flow at 40 to 50C. The amount of the foaming agent(s)
contained in each resin impregnated therewith was as set out in
Table 11.
Expandable resin compositions were prepared each by
20 blending 100 parts of the above obtained resins impregnated
with the foaming agent(s), 2 parts of a tin-containing
stabilizing agent and 1 part of calcium stearate with talc as
a nucleating agent, CELMIC 133 as a decomposable foaming agent
and the styrene-based copolymer resin S-l as a foam-conditioning
agent each in an amount as indicated in Table 11. The resin
compositions were fabricated into foamed rods in the same
manner as in the preceding example. The bulk density of the
thus obtained foamed rods were as set out in Table 11. The
: foamed rods in Experiments No. 133 and No. 134 shrank after
molding.
- 53 -
B
~223~0
~,,, , .. ._. ___ O r~
, ~ o o o
~ o ~ ~o U~ ~
~ ~ ~ 0 ~ o o
_, . o
. ~o oo U~ o~
~1 ~ ON ~-- t~
_ O
" 8 ~ 8 o o o u~ o
,_ -`
~ ~o+~~ a~ o u~ O
_ ~ ~_ _, 0 N O O
~,! O ~m"` _o o ~ o
,Ij Xô ~o o o
~1 ~ ~ o~ ~ oi ~ ~ uO
~1 _ ~ . _ o
~o 0 o o U~ o
o
r_
O 1~ O J
0~ 1~ ~ O Il~ O
_~ .
O
~0 U~ O O ~ 0~
O I
_
.
~ ~ ~ ~ ~ ~ - ~
+~
bO .~ ~ ~ ~ ~a~ ,~
N ~ ~ ~ bl~ h ~ ~ I u~ o
.,, ,~ ~a ~J~ ~ u~ I cn u~
~ ~ ~D ~ ~: ~0 a) ~ ~ a~ ~ ~ Q~ ~
" ." ~_ bO ~ ~ h ~ h ~ ~ 6
,1 Q) ~--1 ~ H ~0 a~ 5: ~ a~
a~ .~ E~ ~ 6 ~t~ ~ ~ h~l ~ ~ 6 h~
~ ~1 ~ ~ ~ ~~ ~1 ~ 07 ~! (a
X o o 6 o ~ ~ ~) ~) ~ o
4-1 H ~1`~ E~ C~ U~ h m
-- 54 --
B`
~223~;~
EXAMPLE 12 (Experiments No. 136 to No. 142)
Into an autoclave of 100 liter capacity made of
stainless steel and equipped with a stirrer were introduced 30 kg
of a copolymer resin composed of 90% by weight of vinyl chloride
and 10% by weight of vinyl acetate and having an average degree
of polymerization of 1,050 and a pore volume of 0.023 ml/g,
50 kg of purified water and 15 g of a partially saponified
polyvinyl alcohol, and then 6 kg of trichlorofluoromethane and
3 kg of butane were introduced into the autoclave with
pressurization followed by agitation at 70C for 8 hours to
impregnate the resin with trichlorofluoromethane and butane as
the volatilizable foaming agents. After completion of
impregnation, cooling to room temperature and discharging of
excess foaming agents, the resin was dehydrated by centrifugal
separation and dried under air flow at 40 to 50C. The total
amount of the foaming agents in the resin impregnated therewith
was 12.0~ by weight.
Expandable resin compositions were prepared each by
blending 100 parts of the above obtained copolymer resin
impregnated with the foaming agents, 2 parts of a tin-
containing stabilizing agent, 1 part of calcium stearate,
1 part of talc as a nucleating agent, 0.5 part of CELMIC 133
as a decomposable foaming agent and one of the styrene-based
copolymer resins S-2 to S-5 as described below as a foam-
conditioning agent in an amount indicated in Table 12. The
resin compositions were fabricated into foamed bodies in the
form of a slab by extrusion molding with an extruder machine
operated as in Example 8.
The thus obtained foamed slabs were examined for
bulk density, cell structure, compression strength and flexural
- 55 -
~22~
strength to give the results as set out in Table 12. In
Experiments No. 141 and No. 142, premature expansion of the resin
compositions took place while still in the die leading to broken
foams and shrinkage of the foamed slabs after molding.
Styrene-based copolymer resins:
S-2: a copolymer resin composed of 70% by weight of
styrene and 30% by weight of acrylonitrile and
having a reduced viscosity of 2.0 dl/g at 25C,
S-3: a copolymer resin composed of 70% by weight of
styrene and 30~ by weight of acrylonitrile and
having a reduced viscosity of 4.0 dl/g at 25C,
S-4: a copolymer resin composed of 70% by weight of
styrene and 30% by weight of acrylonitrile and
having a reduced viscosity of 10.0 dl/g at 25C,
and
S-5: a copolymer resin composed of 75% by weight of
styrene and 25% by weight of acrylonitrile and
having a reduced viscosity of 14.6 dl/g at 25C.
The results given in Table 12 show that a styrene-
based copolymer resin with an increased reduced viscosity as thefoam-conditioning agent can give the advantages of: improved
gas retention or foam building, stabilization of foams and
reduced shrinkage even when the amount of the resin admixed is
relatively small; whereas the use of a resin with a smaller
reduced viscosity leads to broken foams and increased shrinkage
after molding resulting in coarser cell structure, especially,
when the amount of addition is insufficient.
;
~ - 56 -
llZZ350
~ ~ ~ ~,-- ,`
~o o 0 ~
. ~0 ~D ~) ~ ~ . .
U2~ o ~ .
o u~ô J '~ ~O ~O
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J 1
I U~ U~ 'C .
~1 U~OI O ~
c~ JO J '~ O~ 1
~1 __ _ O N
~ _l ~0 O, _ ~, 0~
~ ~0 ~t ~ J
,~ U~CO O '~
~o
. ~ h ~ h ~ON
zo ~ ~: U~ ~1 ~1 ~ h ~:: E3 ~ ~ o
u~ ~1 ~ E~ ~I h ~i h ~) h
O ~ bO ~ +~ ~D
~ ' ~ m ~ b~ ~ ~ ~ ~ ~ x
.,~ S~ h h o~
h ~1 ~ p, vl ~ R
~o~--~ o a~ ~a
Q~ h
. I:L1 Ul h
.
lD
D; - 57-
112~3~
EXAMPLE 13 (Experiments No. 143 to No. 148)
Into an autoclave of 10 liter capacity made of stain-
less steel and equipped with a stirrer were introduced 3 kg of
a homopolymeric polyvinyl chloride resin or a copolymer resin
of vinyl chloride and vinyl acetate, wherein the content of
vinyl acetate, the average degree of polymerization and pore
volume were as given in Table 13, 5 kg of purified water and
1.5 g of a partially saponified polyvinyl alcohol; and then 600
g of trichlorofluoromethane and 200 g of butane were introduced
into the autoclave with pressurization followed by agitation at
70C for 8 hours to impregnate the resin with trichlorofluoro-
methane and butane as the volatilizable foaming agents. After
completion of impregnation, cooling to room temperature and
discharging of excess foaming agents, the resin was dehydrated
by filtration and dried under air flow at 40 to 50C for 5
hours. The total amount of the foaming agents in the resin
impregnated therewith was as given in Table 13.
Expandable resin compositions were prepared each by
blending 100 parts of the above obtained resin impregnated
with the volatilizable foaming agents, 2 parts of a tin-
containing stabilizing agent, 1 part of calcium stearate, 1 part
of talc as a nucleating agent, 0.5 part of CELMIC 133 as a
decomposable foaming agent and a styrene-based resin of the type
and in the amount as indicated in Table 13 as a foam-conditioning
agent. The resin compositions were fabricated by extrusion
molding into foamed rods in the same manner as in Example 7.
The bulk density and cell structure of these foamed rods were
as set out in Table 13. The foamed rod in Experiment 147
shrank to some extent after molding and breakage of the foam
took place in Experiment No. 148 resulting in shrinkage of the
foamed rod after molding.
- 58 -
~D
3~0
The results given in Table 13 show that the styrene-
based resin as the foam-conditioning agent should preferably have
an increased reduced viscosity when the vinyl chloride-based
resin has a relatively large degree of polymerization. A foamed
rod of high expansion with a uniform cell structure can be
obtained even with a vinyl chloride-based resin with zero or a
relatively small vinyl acetate content, which otherwise
requires a relatively high fabricating temperature, by suitable
selection of the foam-conditioning agent.
On the other hand, a copolymer resin having a
relatively low degree of polymerization can give a foamed rod of
high expansion even with a styrene-based resin, as the foam-
conditioning agent, having a relatively low reduced viscosity
when the content of vinyl acetate in the copolymer resin is
large but a foamed rod of high expansion can only be obtained
with difficulty with a copolymer resin of low vinyl acetate
content.
- 59 -
D-` .
llZZ3~
Table 13_ '
I
Experiment No.143 14~ 145 14~ 147 148
_ .
Conten-t of
vinyl acetate, 5 10 0 10 10 0
PVC ~ by weight
., .
resin P 700 1500750 800 1500 850
Vp, ml/g 0.021 0.033 0.0370.021 0.033 0.038
_ =
Im~ r egnation wi th
~`oaming agent, 11 . 5 lO . 5 lO . 1 11. 5 lO . 5 lO . O
/O by we ight
Styrene-based S-5 S-5 S-5 S-3 S-3 S-2
resin (parts) (6) (10) (10)(10) (10) (10)
:.,
Proper- Bulk 0.043 0.059 0.0550.050 0.073 o. 15
ties of density,
foamed g/ml
rod
Cell A A A A A C
structure
l l
~'
-- 60 --
