Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
43-4104A
.
1~5~1150
FOAM PROCESSING AID
Cro~s-References to ~elated A lications
_ PP _ _
None
ack~round of the Invention
This invention relates to improved cellular plastic
materials and to a proceqs for making such materlals.
The ba~ic proce~ses for making a vinyl chloride polymer
"sponge" or "foam" material from a plastisol are well known. In
many of such processes, the plastlsol may be expanded or foamed
and then heated to ~use or sinter the expanded vln~1 chloride
polymer. The formation of the cellular qtructure may be accom-
plished in various ways. One method of foaming a plastiæol is
a process wherein a gas is dissolved in the pla~tisol under
pressure. Upon release of the pre~sure, the dissolved gas expands
in the plastisolJ forming a cellular mass. The plastisol may
al~o be foamed by mechanically beating or whipping alr into the
plastisol. Chemical blowlng agents capable of liberating a gas
below a temperature at which the plastisol gels also have been
extensively employed ln foaming or expanding plastisols. The
mo~t common method~ however~ is the use of blowing agent~, such
as the azodlcarbonamlde typeJ to foam an already fuqed plastisol.
Although other processes for expanding plastisols are available,
the above-mentioned processing techniques are the most widely
uqed.
In the past~ it has been difficult to control the density
and cell size Or polymer foam~, whether formed from plastisols
or by the techniques o~ calendered ~heet and extrusion techniques.
Since the vl~cosities of plastisols used in the manufacture of
mechanically frothed foam materials are relatively low, the
cellular 3tructure of the ungelled foam tends to collapse or
::
-2- ~ ~
~15i~
breakdown i the foam is allowed to stand even for a short
period of time before the plastisol is gelled and fused~
Also, degeneration of the cellular structure of the foamed
plastisol has been experienced when the foamed material is
heated to gel and fuse the plastisol. Additionally, if the
plastisol has a low melt viscosity, the cell structure
degenerates in a very short time period when azodicarbonamide-
type blowing agents are used. Still further, extruded foams,
unless narrowly controlled, will overblow at the die face and
result in a large and irregular cell structure.
In accordance with the present invention, a particu-
lar class of processing aids are provided which, when incor-
porated in a foam formulation, contribute to stabilizing the
structure of the foamed cells, reduce surface imperfections and
decrease the density of certain foams, such as vinyl dry blend
foams.
The following patents have been considered in the
preparation of the present application:
U.S. 2,909,493 discloses a method for making cellu-
:, .
lar vinyl chloride resins which comprises adding materials to
. .
the plastisol which react in the plastisol to form thickening
. . .
agents. The materials which are added to the plastisol, and
which react with each other to form thickening agents within
the plastisol, are an aliphatic acid and a material which
reacts with the acid at a temperature below the gelling tem- ~;
perature of the plastisol (e.g. sodium hydroxide) to form a
fatty acid soap.
U.S. 3,338,845 describes a process for the prepara-
tion of foamed materials which comprises heating an organic ~ ~
isocyanate with a secondary amine, such reaction being carried ~;
out in the presence of a polyvinyl halide and an additional
-3-
51~5~ `
substance which is reactable with the isocyanate. Such
reactable material is certain disclosed alcohols and `~
naphthenic acids~ ~
U.S. 3,409,580 discloses a plastisol comprising a `
polyvinyl halide, a piasticizer therefor and a small amount
of an amine which acts to improve Elow characteristics and
froth stability of the plastisol. In addition to the amine,
a naphthenic acid or an ether alcohol may be used.
U.S. 3,454,507 discloses the preparation of foamed ;
polyvinyl chloride compositions in the presence of a pore-
size controlling additive which is a copolymer of at least
one unsaturated compound and one compound which is a deriva-
tive of a mono- or di-protic unsaturated acid. Typical
copolymers disclosed are copolymers of methacrylates and
fumarates and copolymers of a long chain alkyl ester of
acrylic or methacrylic acid with an acrylic or methacrylic
acid ester of a polyalkylene glycol. The copolymers may also
comprise other comonomers such as ethyl acrylate and the like.
A typical additive comprises the reaction product of
2-ethylhexyl acrylate, ethyl acrylate and a polyethylene
glycol methacrylate. At least one of the monomers utilized
to prepare the pore size controlling additive must contain at
least one polyoxyalkylene residue terminated with an alkyl,
aryl, aralkyl, alkaryl or acyl group.
In accordance with the present invention there is
provided a class of foam processing aids which include liquid
homopolymers of alkyl acrylate esters wherein the alkyl
radical is linear or branched chain and contains from 1 to
about 24 carbon atoms, and liquid copolymers of an alkyl
acrylate ester with a dissimilar alkyl acrylate ester.
~ -4-
.
.
,.
~63 S~L~L5~
In a preferred embodi.ment of the present invention
there is provided a composition comprising a foamed plastic
and from about 0.025 to about 2.0 percent, based on the
weight of said plastic, of a processing aid consisting of a
liquid polymer of one or more alkyl acrylate esters wherein
the alkyl radical in each of said esters contains from 1 -:
to about 24 carbon atoms, said polymer having a molecular
weight of from about 2,000 to about 10,000 and being a homo ;
polymer of an alkyl acrylate ester or a copolymer consisting
of an alkyl acrylate ester copolymerized with a dissimilar .
alkyl acrylate ester.
In a further embodiment of the present invention .-
there is provided a method of improving the processability `
and characteristics of plastic foams which comprises incor~
porating therein from about 0.025 to about 2 percent, based .
on the weight of said plastic, of a processing aid consisting
of a liquid polymer of one or more alkyl acrylate esters : ~
wherein the alkyl radical in each of said esters contains .. : :
~ .
from 1 ~o about 24 carbon atoms, said polymer having a molecu~
20 lar weight of from about 2,000 to about 10,000 and being a
homopolymer of an alkyl acrylate ester or a copolymer consis- .- ~
ting of an alkyl acrylate ester copolymerized with a dissimilar :
alkyl acrylate ester. ~ .
'`: ':, .,
Utilization of the processing aids provided by the
present invention afford improved cell structure and
stabilization thereof, reduction of surface imperfections of
the foamed material and the preparation of foams having
decreased density. ~:
The foam processing aids provided by the
present invention include liquid homopolymers of alkyl
,'' `''
-4a- .
1~5~l~5~ -
acrylate esters wherein the alkyl radical is linear or
branched chain and contains from 1 to about 24 carbon atoms,
and liquid copolymers of an alkyl acrylate ester with a
dissimilar alkyl acrylate ester. Preferred alkyl acrylate
homopolymers are those wherein the alkyl radical contains
from about 3 to about 12 carbon atoms, e.g. polypropyl
acrylate, polybutyl acrylate, polyhexyl acrylate, poly-
octyl acrylate, polydecyl acrylate, polydodecyl acrylate.
The copolymers consist o-f ~1) from about 5 to about
95% by weight of an alkyl acrylate ester wherein the alkyl
constituent contains from about 1 to about 12 carbon atoms
and ~2) from about 95 to about 5% by weight of a dissimilar
alkyl acrylate ester wherein the alkyl constituent contains
from about 3 to about 24 carbon atoms. In a preferred
embodiment of the invention, the processing aid consists of
a copolymer of (1) from about 5 to about 95% by weight of
an alkyl acrylate ester wherein the alkyl constituent contains
from about 1 to about 12 carbon atoms and (2) from about -
95 to about 5~ by weight of a dissimilar alkyl acrylate
ester wherein the alkyl constituent contains from about 3
to about 18 carbon atoms. In a yet more preferred embodi-
ment of the invention, the useful modifying copolymers con-
sist of (1) from about 2~ to about 50% by weight of an
alkyl acrylate ester wherein the alkyl constituent contains
from about 2 to about S carbon atoms and (2) from about 80
to about 50% by weight of a dissimilar alkyl acrylate ester
wherein the alkyl constituent contains from about 6 to
about 12 carbon atoms.
The processing aids utilized herein are characterized
43-4104A
,
~S~LS~ .
by their liquidity, ranging from free-flowing to viscous at
room temperature or slight~.y above. The polymers have an average
molecular weight of from about 2000 to about 1OJOOOJ a pref'erred
molecular we~ght range being from about ~OGO to about 6000.
particularly useful molecular weight range is from about 3500 t~
about 5000.
Tough or rubbery acrylic materia].s such as those fre-
quently used AS extenders or impact value modj.fiers are unsuitable
for use as processing aids in accordance with the purposes of ~:
this invention. . .
Typical acrylic polymeric materials whlch are util.i~e~
as processin~ aids in accordance with the present invention
i.nclude the following: ~ :
Copolymer of 50 parts of 2-ethylhexyl acrylate and :
50 parts of octadecyl acrylate (molecular weight - 4,040)
Homopolymer of octadecyl acrylate (molecular weight =
2,470)
Homopolymer of lauryl acrylate (molecular weight = 1,980) ..
Copolymer of 30 parts of ethyl acrylate and 70 parts
of 2-ethylhexyl acrylate (molecular weight = 4,690)
Copolymer of 30 parts of ethyl acrylate and 70 parts
of 2-ethylhexyl acrylate (mo~.ecular weight = 3,600) ;
Homopolymer of propyl acrylate
Homopolymer of butyl acrylate .. :
Homopolymer of heptyl acrylate
Homopolymer of nonyl acrylate :-
Homopolymer of decyl acrylate
Homopolymer of tetradecyl acrylate
Homopolymer of hexadecyl acrylate :
Copolymer of 85 parts of hexyl acrylate and 15 parts of
propyl acrylate
... ..... . .. . .. . .
43~4104A
~51~50
Copolymer of 25 parts of heptyl acrylate a~d 75 parts
of nonyl acrylate
Copolymer of 35 parts of amyl acrylate and 65 parts of
dodecyl acrylate
Copolymer of 45 parts of decyl acrylate and 55 parts
of heptadecyl acrylate
Copolymer of 15 parts of dodecyl acrylate and 85 parts
of butyl acrylate
Copolymer of 75 parts of dodecyl acrylate and 25 parts
of pentadecyl acrylate ~:
Copolymer of 60 parts of nonyl acrylate and 40 parts of
decyl acrylate
Copolymer of 45 parts o~ ethyl acrylate and 55 parts .
of dodecyl acrylate
Copplymer of 40 parts of ethyl acrylate and 60 parts
of 2-ethylhexyl acrylate (molecular weight = 6,760)
Homopolymer o~ lauryl acrylate (molecular weight = 8,930)
Copolymer of 90 parts of methyl acrylate and 10 parts
of butyl acrylate (molecular weight - 10,230)
Copolymer of 80 parts of butyl acrylate and 20 parts of
lauryl acrylate (molecular weight = 5,410) .~ .
Copolymer of 40 parts of butyl acrylate and 60 parts
o~ lauryl acrylate (molecular weight = 6,790)
Homopolymer of octadecyl acrylate (molecular weight =
3,200)
Copolymer of 30 parts ethyl acrylate and 70 parts of
2-ethylhexyl acrylate (molecular weight = 4,760)
Copolymer of 90 parts of ethyl acrylate and 10 parts
of butyl acrylate (molecular weight = 5J320)
Homopolymer of lauryl acrylate (molecular weight = 7,400)
l~)5~ lS~ `
Homopolymer of methyl acrylate (molecular weight =
8,920)
Copolymer of 90 parts of methyl acrylate and 10 parts -
of butyl acrylate (molecular weight = 2,100)
Homopolymer of methyl acrylate (molecular weight =
9,730)
Homopolymer of lauryl acrylate (molecular weight =
9,500)
The foamed materials which are used in the composi-
tions of this invention may be any foamed materials. Such
foams may be utilized in various techniques such as powder
casting of plasticized dry blend foams, rotational molding of
vinyl foam dry blends, injection molding of vinyl foams, calen-
dered vinyl foams, low density vinyl -foams formed from plasti-
sols, extrusion of rigid vinyl foams, extrusion and injection -
molding of polyolefin foams and similar techniques. Any plas-
tic materials capable of being formed into a foam composition
are useful in the compositions of the present invention. ;
The concentration of the acrylate processing aid in ~
the polymer foam will vary with the particular polymer foam ;
system being used and with the size of the polymer particles,
thus indicating that a surface phenomenon occurs. Generally,
the amount of processing aid which is added will be from
about 0.025 to about 2 percent by weight, based on the weight
of the foam. Preferably, the processing aid is added at a
level of from about 0.05 to about 0.25 percent in powder coat-
ing formulations, from about 0.25 to about 0.75 percent in
plastisol formulations, from about 0.05 to about 0.25 percent
in calendering formulations, from about 0.05 to about 0.50
percent in extrusion formulations, from about 0.05 to about
0.50 percent in injection molding formulations and
.
~ -8-
~ ~ .
. . .
1~5~S~
from about 0.10 to about 0.75 percent in rotational molding
formulations.
Illustrative of foamed thermoplastic materials
which may be advantageously modified in accordance with the
present invention include the polyacetals, polyacrylics,
chlorinated polyethers, polyfluorocarbons, nylon molding com-
pounds, polyolefins, polycarbonates, vinyl polymers and co~
polymers, urethane elastomers and the like. ~-
Specifically, an important class of foamed polymers
which are beneficially modified with the acrylic materials of
the invention are those obtained from a polymerizable monomer
compound having ethylenic unsaturation.
A particularly preferred class of foamed polymers
which are used consist of the polymerized vinyl and vinylidene
compounds, i.e., those having the CH2 = C ~ radical. Compounds
having such a radical are, for example, the solid polymeric
alkenes, such as polyethylene, polypropylene, polyisobutylene
or ethylene/propylene copolymers; polymerized acrylyl and
alkacrylyl compounds such as acrylic, fluoroacrylic and meth-
acrylic acids, anhydrides, esters, nitriles and amides, for
example, acrylonitrile, ethyl or butyl acrylate, methyl or
ethyl methacrylate, methoxymethyl or 2-(2-butoxyethoxy)ethyl
methacrylate, 2-(cyanoethoxy) ethyl 3-(3-cyanopropoxy) propyl
acrylate or methacrylate, 2-(diethylamino)ethyl or 2-chloro-
ethyl acrylate or methacrylate, acrylic anhydride or methacry-
lic anhydride; methacrylamide or chloroacrylamide; ethyl or
butyl chloroacrylate; the olefinic aldehydes such as acrolein,
methacrolein and their acetals, the vinyl and vinylidene
halides such as vinyl chloride, vinyl fluoride, vinylidene
fluoride and l-chloro-l-fluoroethylene; polyvinyl ;
alcohol; the vinyl carboxylates such as vinyl acetate,
43-4104A
"
~ 5~S~
viny~ chloroacetate, vinyl propionate, and vinyl 2-ethylhexa-
noate; the N-vinyl imides such as N-vinyl phthalimide and N-
vinyl succinamide; the N-vinyl lactams such as N-vinyl capro-
lactam and N-vinyl butyrolactam; vinyl aromatic hydrocarbon :
compounds such as styrene, alphamethylstyrene, 2,4-dichloro-
styrene, alpha- or beta-vinylnaphthalene, divinyl benzene an~ ~.
vinyl fluorene; the vinyl ethers such as ethyl vi.nyl ether or
isobutyl vinyl ether; vinyl-substituted heterocyclic compounds :.
such as vinyl pyridine, vinyl pyrrolidone, vinylfuran or vi.nyl-
thiophene; the vinyl or viny}idene ketones such as methyl vinyl
ketone or isopropenyl ethyl ketone, vinylidene cyanide. Foams
of homopolymers of the above compounds or copolymers and ter-
polymer.s thereof are beneficially used in the compositions of
the present i.nvention. Examples of such copolymers or terpolymers ..
are those obtained by polymerization of the following monomer
mixtures; vinyl chloride/vinyl acetate, ethylene/vinyl chloride/
vinyl acetate, acrylonitrile/vinyl pyridine, styrene/methyl
methacrylate, styrene/N-vinyl pyrrolidone, cyclohexyl metha-
crylate/vinyl chloroacetate, acrylonitrile/vinylidene cyanide,
m~thyl methacrylate/vinyl acet~te, ethyl acrylate/methacrylamide/
ethyl chloroacrylateJ vinyl chloride/vinylidene chloride/vinyl .
acetate. : .
Other foamed polymers of compounds having the ethylenic
group, ~ C = C \ , are homopolymers, copolymers and terpolymers - ...
of alpha-, beta-olefinic dicarboxylic acids and derivatives
thereof of such as the anhydrides, esters, amides, nitriles and
imides, f`or example~ methylg butyl, 2-ethylhexyl or dodecyl fuma-
rate or maleate; maleic, chloromaleic, citraconic or itaconic .:
anhydride; fumaronitrile, dichlorofumaronitrile or citracononitrile;
fumaride, maleamide or N-phenyl maleamide. Examples of parti
-10- ~ .
43-4104A
:~S3~:~S~
cularly useful polymers and terpolymers prepared from the alpha-,
beta-olefinic dicarboxylic compounds are the copolymers of maleic
anhydride and a vinyl compound such as ethylene, propylene, iso- :.
butylene, styrene, alpha ~ethylstyrene, vl.nyl acetate, vinyl
propionate, methyl isopropenyl ketone, isobutyl vinyl ether, the
copolymers o~ dialkyl fumarate such as ethyl or butyl fumarate
and vinyl compounds such as styrene, vinyl acetate, vi.nylidene
chloride, ethyl methacrylate, ac.rylonitrile and the li.kc.
The compounds Or the invention act as processing ai.ds
for the foamed polymers and copolymers of unsaturated, cyclic
esters of carbonic acid, ~or example, homopolymeric vinylene
carbonate or the copolymers of v~.nylene carbonate with ethylenic ~-
compounds such as ethylene, vinyl chloride, vinyl acetate, 1,3-
butadiene, acrylonitrile, methacrvlonitrile, or the esters of
methacrylic or acrylic acid.
The compoun~s of the invention are also used as pro-
`` cessing aids for foams of polyarylcarbonate polymers such as thelinear polyarylcarbonates formed from diphenols or dihydroxy
aromatic compounds including single and fused-r~ng nucleii with
2G two hydroxy groups as well as monohydroxy-substituted aromatic
residues joined in pai.rs by various connecting linkages. Examples
of the foregoing include dihydroxy benzenes, naph~a.lenes and
the like, the dihydroxydiphenyl ethers, sulfones, alkanes, ketones
and the like.
The compounds of the invention also act as processing
aids for foamed polymers, copolymers or terpolymers of poly-
merizable compounds having a plurali.ty of double bonds~ for ex-
ample, rubbery~ con~ugated diene polymerizates such as homopoly-
merized 3-butadiene, 2-chlorobutadiene or isoprene and linear
copolymers or terpolymers such as butadiene/acrylonitrile, iso-
--11--
.... ..
43-~lO~A
~OS~S~ ' '
butylene/butadiene, butadiene/styrene; esters of saturated di-
or poly-hydroxy compounds with olefinic carboxylic acids such as
ethylene glycol dimethacrylate, triethylene glycol dicrotonate
or glyceryl triacrylate; esters o~ olefinic alcohols with dicar-
boxylic acids or with olefinic monocarboxylic acids such as
diallyl adipate, divinyl succinateJ diallyl fumarate, allyl meth-
acrylate or crotyl acrylate and other diethylenically unsaturated
compounds ~uch as diallyl carbonate, divinyl ether or divinyl-
benzene, as well as the crosslinked polymeric materials such as
~0 methyl methacrylate/diallyl methacrylate copolymer or butadiene/
styrene/divinyl benzene terpolymer.
The compounds of the present invention are well suited
as processing aids for foamed resin compositions o~ the polyester
type, for example, the linear polyesters which are obtained by
the reaction of one or more polyhydric alcohols with one or ~ore
alpha, beta-unsaturated polycarboxylic acids alone or in combi-
nation with one or more saturated polycarboxylic acid compounds,
or the crosslinked polyester resins which are obtalned by reacting
a linear polyester with a compound containing a CH2 = C group. ~ :
The compounds o~ the present invention are processing
aids for foamed epoxy resins. Such resins are condensation
products formed by the reaction of a polyhydroxy compound and
epichlorohydrin, which condensation products are subsequently
cured by the addition of crosslinking agents. The hydroxy com~
pounds may be, ~or exampleJ ethylene glycol, 4,4l-isopropyli-
denediphenol and similar materials. The crosslinking agent
employed in the curing step may be a dicarboxylic compound such
as phthalic anhydride or adipic acid, but is more generally a
polyamine such as ethylene diamine, paraphenylamine diamine or
diethylene triamine.
-12-
- : ~ : . . .
43-4104A
.
:l~Sl~S(~
Foamed polyurethanes are a class of polymer materials
which are used in accordance with the present invention. The
polyurethanes, like the above-mentioned polyesters, are materials
which are employed i.n structural applications, ~or example, as
insulating foams. Essentially, the polyurethanes are condensati.on
products of a diis~cyanate and a compound having a molecular weight
of at l.east 500 and preferably about 1500-500C and at least two
reacti.ve hydrogen ions. The use~ul active-hydrogen containing
compounds may be polyesters prepared from polycarboxylic acids
and polyhydric alcohols, polyhydric polyalkylene ethers having
at least two hydroxy groups, polythioether glycols, polyester-
amides and similar materials.
The polyesters or polyester amides used for the pro-
ducti.on of the polyurethane may be branched and/or linear, for
example, the esters of adipic, sebasic, 6-aminocaproi.c, phthalic,
isophthalic, terephthalic, oxalic, malonic, succinic, maleic,
cyc].ohexane-1,2-dicarboxylic, cyclohexane-1,4-dicarboxylic,
polyacrylic naphthalene-1,2-dicarkoxylic, fumaric or itaconic ~:
acids with po].yalcoho].s such as ethylene glycol, diethylene
glycol, pentaglycol, gl.ycerol, sorbitol, triethanolamine and/or
amino alcohols such as ethanolamine, 3-aminopropanol, and with
mixtures of the above polyalcohols and amines.
The alkylene glycols and polyoxyalkylene or polythio-
alkylene glycols used in the production of polyurethanes may be
ethylene glycol, propylene glycol, butylene glycol, diethylene
glycol, triethylene glycol, polythioethylene glycol, dipropylene
glycol and the like.
Generally~ any of the polyesters, polyisocyanate-modified
polyesters, polyester amides, polyisocyanate-modified polyester~
amides, alkylene glycols, polyisocyanate-modified alkylene glycols,
43-4104A
~S~L15~ ~
polyoxyalkylene glycols having three reactive hydrogen atoms, :
three reactive carboxylic and/or especially hydroxyl groups rnay
be employed in the proAuction o~ polyurethanes. Moreover, any
organic compound containing at least two radica~s selected from
the group consisting of hydroxy and carboxy grouI)s may be
employed.
The organic polyisocyanates useful for the production
of polyurethanes include ethylene dilsocyanate, ethyl.idene
dlisocyanate~ propylene-1,2 di.isocyanate, m-phenylene diisocyanate,
2,4-tolylene diisocyanate, triphenylmethane triisocyanate, or
polyisocyanates in blocked or inactive form such as the bis-phenyl ~:
carbamates of tolylene diisocyanate and the like.
The compounds of the present invention are also ~Ise~ul
as processing aids for fo~med linear polymers obta-Lned by the
self-condensation of bifunctional compounds, for example, the
polyethers which are derived by the self-condensation of dihy~ric
alcohols such as ethylene glycol, propylene glycol or hexamethy- :~
lene glycol; the polyesters which are obtained by the self-con-
densation of hydroxy acids such as lactic acid or 4 hydroxybutyri.c
acid; the polyamides which are prepared by the self-condensati.on
of aminocarboxyli.c acids such as 4-aminobutyric acid; the poly-
anhydrides which are formed by the self-condensation of dicarboxylic
acids such as sebasic or adipic acid.
The preferred foamed synthetic polymer materials which .
are used in the compositions of the present invention are the
foamed vinyl halide polymersJ rigid and flexible polyurethane
foams, foamed epoxy resins, ABS and GRS foamed rubbers. The vinyl
halide polymers can be simple, mixed homopolymers of vinyl chlo-
ride or polyvinylidene chloride, or copoly.ners or terpolymers
in which the essential po].ymeric structure of polyvinyl chloride
-14-
. ,- . .
43 410~A
~51~5~ : -
is interspersed at intervals with res~dues of other ethylenically
unsaturated compounds copolymerizable therewith. The essential
properties of the polymeric structure of polyvinyl ch~ oride is
retained if not more than about 40 percent of a comonomer is
copolymerized therewith. Especlally preferred copolymers include
ethylene/vinyl chloride and vinyl chloride/acry~onitrile copolymers.
Especially preferred terpolymers include ethylene/vinyl chloride/
acrylonitrile, ethylene/vinyl chloride/acr~lic acid and ethylene/
vinyl chloride/acrylamide terpolymers.
Accordingly~ it is apparent that the processing aids
of the present invention may be used with ~ny plastic material
whether thermoplastic or thermoset in charact~r.
The polymer formulations which are used in accordance
with the present invention may contain various conventional ad-
ditives such as fillers~ extenders, crosslinking agents and
colorants. Minor amounts of stabilizers, for example, are usually
incorporated to reduce the effects of heat and ]ight.
The foamed composition may be formed from a self-blowirlg
polymer or the polymer may be blown by chemical or mechnaical
~0 means or by the use of compressed gas. Fillers which are frc-
quently employed to lower the cost of the finished material and
to modify its properties include calcium carbonate and magnesium
silicate. When fillers are employed, they are generally present
in an amount of up to about 150 parts by weight of ~iller per
100 parts by weight of polymer formulation.
Where a colored or tinted composition is desired, colo-
rants or color-pigments are incorporated in amounts of from about
one to about five parts by weight to 100 parts by weight of polymer.
Surfactants such as silicones are normally added to
~0 foam formulations which are mechanically frothed. The surfactants
reduce the surface tension of the foam and thereby increase the
air or gas entrapment characteristics of the ~oam.
-15-
` 43-4104A
~L~59~LS~ `
The acrylate processing aids described herein and the
methods of their production are well known to those skilled in
the art. The polymers can be obtained ~or example, by solution
polymerization of a monomer or a mixture of two monomers in an
inert organic diluent while in contact with a peroxidic catalyst.
Another method for preparing the disclosed processing aids
is by a mass polymerization process wherein a monomeric ingredient
or mixture of monomeric ingredients is mixed with a polymeri-
zation catalyst at a temperature sufficient to cause ~olymeri-
zation. Emulsion polymerization procedures which entail poly-
meriæing a monomer or a mixture of monomers as an emulsion in
the presence of a suitable emulsifying agent are also suitable
for the preparation of the processing aids of this invention.
In the emulsion polymerization procedure, which is the preferred
process for preparing the acrylate resins~ polymerization of the
monomer or mixture of monomers is effected in the presence of
water which contains dissolved therein a suitable catalyst and an
emulsion stabiliæing agent. Examples of suitable catalysts include
ammonium persulfate, benzoyl peroxideJ hydrogen peroxide, sodium
perborate and other water-solubles of peroxy acids. I'he peroxy
compounds useful as catalysts may be present in amounts from
about 0.02 to about 2.0 percent by weight of the polymerizable
compounds. Illustrative of the emulsion stabilizing agents
useful in this process are various wetting agents, which are in
general organic compounds containing both hydrophobic and hydro-
philic radicals such as sodium alkyl sulfate, sulfated aromatic
ether alcohols, sodium akyl aryl sul~onates, ~atty alcohol sul-
fates, sorbitan trioleate and the like. The emulsion polymerization
is ordinarily carried out at a temperature in the range of ~rom
~0 65co to 95C. depending upon the nature of the polymerization
system and the particular catalyst used.
-16-
1(3 S~L5~1t
The invention will be more readily understood by refe-
rence to the fol.Lowing examples in which parts are ~iven by wei~ht
unless otherwise stated. There are, of courseJ many other forms
of this invention which will become obvious to one skiLled in the
art once the invention has been fully disclosed and lt w-ill
accordingly be re~ognized that these examples are given for the -~
purpose o~ illustrating specific embodiments of the inventlon only
and ~re not to b~ con~trued as limiting the scope of this inven~
tion in any way.
In the following examples, all proportions of mater~als
are given in parts by weight.
EXAMPLE 1
This example lllustrates the effect on foam density
of an acrylate copolymer of the i.nvention ~ethyl acry].ate/~-
ethylhexyl acrylate, 30/70) in flame retarded PVC dry blend
~oams.
The ~llowing resi.n formulations are prepared:
Batch
I,~,redlent =~
Polyvinyl chloride resin 100 ~OG 100
2 ' 5 5 5
Stab~lizer 3 3
Blow~ng agent 4 4 4
Filler 20 20 20
s
Acrylate ~opolymer ---- 0.1 0.1
.. .. .
Santicizer 711, a mixed phthalate prepared from a mixture
of C~ C~, Cll alcohols and phthalic anhydride. Presently
availab:L~ from Monsanto Company.
~ DyphosR, ~National Lead) - dibasic lead pho~phite
KemporeR SD125 - azodicarbonamide (50~ active)
DuramiteR - CaC03
Ethylacrylate/2-ethylhexyl acrylate copolymer (30/70)
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43-4104A
.. . .
~1315115~
The resin batches are prepared using a spatula mix
in the follo~Jing sequence.
1. Heat liquids to 50C. for 10 min.
2. Heat resin for 10 min. at 77C.
3. Add liquids to resinJ mix and dry
for 10 min. -
. Add CaCn~ and (Rt 77C.) Batch No. 1 ~or
30 min.; Batch No. 2 for 30 min.: Batch
No. 3 for 40 min.
The foam densities (processed at 1~5C.) are as
follow~:
; Batc~ No. 1: 29.5 lbs. per cu.ft.
Batch No. 2: 24.2 lbs. per cu.ft. ;
Batch No. 3: 23.7 lbs. per cu.ft.
The data indicate that addition of the acrylate co-
polymer lowered the foam density (thus affording a f~am having
enhanced rebound characteristics) and that overdrying ~Batch
No. 3) did not adversely affect the blend. By using the acrylate
copolymer, a drier blend is obtainable which is casier to work
with in powder coating operations. The problem of foam deterl- ~
oration at longer drying times is t!hus overcome. :
Similar advantageous results are afforde~ when processing
aids other than di~2-ethylhexyl acrylate are used, especially
medium to long chain alkyl acrylates, and when other polymers
are substituted for PVG, i.e. polyurethanes, rubbery foams,
polycarbonates and polyester foams.
EXAMPLE 2
This example illustrates the effect of acrylate co-
polymer concentration on cell structure and ~o~m density of
flame retarded PVC dry blend foam.
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~S~lSal
PVC foam samples are prepared by spatula mixing using
the following procedure:
. Dry lngredients are heated for 10 min. ~t 77C. and
liqui.d ingredients are heated for 10 min. at 50C. The dry in
gredients are then combined with the liquid ingredients ~nd
sp~tula mixed. The ingredients are further blended for 10 min.
at 11'7C. and ~lame retardant ls added. The total mlx i.~ then
dried an additional 15 mln. at 77C. The dr~e~ blend~ ~re then
fused for 5 min. at 185C.
The followi.ng formulations are prepared in the above-
described manner:
Batch
Ingredient No.l No.2 ~R~ No.4 No.5
Polyvinylchloride resin100 100 100 100 100
Plasticizer 25 25 25 25 25
Plasticizer 25 25 25 25 25
Stabi.lizer 3 ~ ~ 3 3
Blwoing Agent 4 4 4 4 4
Flame retard~nt 20 20 20 ~0 20
2Q Acrylate copolymer ____ 0.05 0.1 0.25 0-5
Density ~ cu.ft. ~ 29.0 .26.5~4.720.726.0
SanticizerR 711 (Monsanto) - mixed C7_ll phthalate esters
SanticizerR 148 (Monsanto) - isodecyl diphenyl phosphate
DyphosR (Na~ional Lead) - dibasic lead phosphitc
KemporeR SD125 (50~ active)
PhosgardRLSV (Monsanto) - propri.etary phosphoru~ Lormula-
tion presently av~ilable
-Ethy~ acryl~te/2-ethylhexyl acrylate (30/70)
The data indicate that addition of ac~ylate copolymer
~0 lowered foam den~ity at acrylate concentrations of 0.05,.0~1 and
0.25 parts. At 0.5 part~ acrylate, the foam den6ity increa~ed.
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~L~S~LlS(~
Accordingly, lowered foam densities are afforded at acrylate
concentrations of less than 0.5 parts. Additionally, visual
and microscopic observation of the prepared foams indicate
that, although 0.25 parts acrylate copolymer affords the
lowest density of the above batches, the cell size was equiva-
lent to the cell size of the control. At ~.1 parts acrylate
copolymer, the cell structure is much improved (i.e. uniform)
and at a 20 percent lower density than the control.
Similar results are afforded when PVC is substituted
by polyolefins, e.g. polyethylene, and epoxy foams.
While the invention has been described hereinabove
with regard to certain illustrative embodiments, it is not
so limited since many modifications and variations are possible
in the light of the above teachings. It is understood there- ;
fore that -the invention may be practiced otherwise than as ;
specifically described without departing from the spirit and
scope of the invention.
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