Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
1920090
~liJ/o~
POLYVINY~ ~A$ID~ COMPOUND~ EAVING I~PROV~D ~URFACEB
AND ARTICLE~ T~EREF~OM
FI~LD OF ~HE INVENTION
S This disclosure pertains to the field of a lubricant
systems for polyvinyl halide resin. In particular, the
invention pertains to impact modified polyvinyl chloride
compounds, and lubricant systems incorporated therein for
improved low temperature impact, high surface gloss and
gloss retention after thermoforming. The invention also
pertains to rigid or semi-rigid extruded, molded or
thermoformed articles including appearance layers in a
multi-layer article having layers of similar or dissimilar
polymer matrices.
AC~GRO~ND OF TH~ INV~NTION
¦ A variety of compounding additives for polyvinyl
halide are well established in the art. Particularly,
lubricants for rigid polyvinyl halide are essential for
processing of rigid PVC and are characterized for their
inter-particle activity as in the case of external
lubricants or their intra-particle activity as in the case
of internal lubricants. The term particles herein
specifically pertain to the micron sized primary particles
resulting from the breakdown of agglomerates of polyvinyl
halide undergoing fusion and flow in a melt-process stream.
The term "melt" is not technically precise, as polyvinyl
halide polymers lack sufficient crystallinity to undergo a
sharp melt transition. Processing of PVC i6 in some
instances achieved in a temperature range and work load
such that less than the entire volume matrix is in a true
'
- 2 - ~ J ~ 7~
melt state and some of the material passes through the
processing zone as partially fused primary particle flow
units. A detailed treatise on the behavior of PVC
undergoing fusion in the melt process is found in Summers,
J. W., A Review Of PolYvinvl Chloride Mor~holoav And
Fusion, SPE RETEC- Chicago Section, 1986.
Often a balance is sought in incorporation of internal
and external lubrication because several end-product
physical properties are adversely affected by over- or
under lubrication. It is generally understood that under-
lubrication of polyvinyl halide results in shortened time
until degradation ensues, beginning with premature fusion
and rapid viscosity rise followed by degradation and
discoloration. Over-lubrication is often associated with
less than optimal fusion and work level imparted to the
mass, thus resulting in poor tensile and impact strength,
under these circumstances. ~
:, :;::
An extensive art for lubrication of PVC has been
previously published. U.S. Patent No. 4,824,583, for ;~
example teaches the lubrication of rigid PVC with a
combination of saponified triglyceride, and oxidized
polyolefin. The desired effects are seen in the
comparison of the extent of discoloration after time at -~
190C melt processing. Absent is a teaching to the effect
of this lubricant system on surface gloss or resulting
physical properties of the compound. Optimization of these
properties takes on greater importance assuming that -~
processing conditions do not entail discoloration by over~
1 30 working the compound. That is, within a reasonable
processing window for any given compound, it is important
to determine the effect of the lubrication system on
~,
- 3 ~
physical properties. The extent of extended work
capability is only one aspect evidencing the safety margin
to be expected in processing a given compound.
U.S. patent No. 4,481,324 is a detailed teaching on
the nature of polyglycerol structure on lubrication of PVC.
The focus is on processing stability and gloss effects
imparted by adjusting the internal/external lubricating
mechanism via the degree of polymeriæation (Dp), the degree
of esterification (n) and carbon chain length (Cx) of the
ester group. External lubricants (higher Dp, "n", and Cx)
are characterized by migration to the metal-polymer
interface in processing, generally yielding surface gloss
while delaying fusion according to amount used. ~his is
contrasted with internal, more polymer soluble lubricants,
for example glycerol monostearate. According to the
empirical data of U.S '324, glycerol monostearate exhibits
a relatively short fusion time of 6 minutes under the
controlled Brabender fusion test, and would not contribute
to surface gloss enhancement. Moreover, fusion time is not
affected by an increase in amount of glycerol monostearate
used. The inventive lubricants of U.S. '324 are those
exhibiting higher dynamic stability time (DTS) and higher
gloss, that is, di-glycerol- mono, di and tri ester of C12
I to C20 acid.
The study of lubrication per se in simple compounds of
polyvinyl halide does not reveal a complete picture
additionally because commercial compounds must contain a
variety of other ingredients. Each ingredient imparts first
order and second order effects. Process aids, impact
modifiers and pigments have a drastic effect on overall
properties, and lubrication with these components present
-
must be adapted, there being no predictable rules or
extrapolations available for the practitioner. Moreover,
stabilizers, lubricant systems, pigments and impact
modifiers often create interferences with each other in
attaining an acceptable balance of the critical properties
in modified PVC compounds. Thus, one impact, lubricant or
stabilizer system individually optimized does not suggest
the best combination nor is predictive of successful
utilization in a PVC compound. The best balance in all
three critical performance attributes- processibility,
gloss and physical properties are desired. In as much as
high surface gloss, high processibility and good physical
properties in the best balance are desired, extensive
studies aimed at this objective have been undertaken with
the result that particular preferred lubricant, impact and
pigmentation systems have been found which impart a
superior balance of gloss, processing stability, impact
strength, and HDT.
~UMMARY OF T~E INVENTION
¦ 20 In one aspect, this invention is directed to high
gloss polyvinyl halide compounds. The object of the
invention is the maximization of surface gloss, impact
strength and processing stability for extruded or molded
compounds by the incorporation of additive systems
disclosed hereinbelow. These aspects are generally
achieved for a polyvinyl chloride compound comprising from
0.01 to 10 phr ~ ~;
,~
7 ~ J ~
each of: glycerol monostearate, fatty salt, hydrocarbon,
and a fatty acid in specified amounts to provide high
gloss, gloss retention, processibility and physical
properties. The preferred embodiments are further limited
by: the amount of impact modifier, optional rutile titanium
dioxide, an absence of mineral wax lubricant, epoxidized
material and less than about 2 parts each per hundred parts
polyvinyl halide (phr) of carboxylic salt, and monoester of
glycerol. The compounds of this invention are rigid and
exhibit an HDT under a 66 psi load of at least 60C and
exhibit an improved balance of variable height impact
strength (VHIT), room temperature Izod, -40C Izod impact
strength and dynamic process stability (DTS).
DE~TAII.ED DESCRIPTION
In general, the components of the compounds of the
present invention are polyvinyl halide, stabilizer, impact
modifier, a lubricant system and optional ingredients such
as pi~nent, filler, and colorant, etc., each specified
herein. In particular, the preferred embodiment of the
invention comprises in a specified amount polyvinyl
chloride homopolymer, an acrylic impact modifier, an MBS
impact modifier, a tin stabilizer, epoxidized vegetable
oil, mineral oil, a long chain carboxylic acid, a metal
salt of a long chain carboxylic acid, and an alkyl ester of
an alkyl polyol, preferably a mono -C16 to C18- ester of
glycerol. Preferred optional components are coated
titanium dioxide, and polymeric acrylic processing aid.
Rigid compounds of this invention are distinguished
from non-rigid compounds. Rigid compounds of this
- 30 invention conform to the definition of ASTM-D883 for rigid
-
::
plastics that have a modulus of elasticity, either in
flexure or in tension, greater than 700 Mpa (100,000 psi)
at 23C and 50% relative humidity when tested in accordance
with either ASTM Method D747 - Test for Stiffness of -
Plastics by Means of a Cantilever Beam, ASTM Method D790 -
Test for Flexural Properties of Plastics and Electrical
Insulating Materials, ASTM Method D638 - Test for Tensile
Properties of Plastics, or ASTM Method D882 - Test for
Tensile Properties of Thin Plastic Sheeting tlg83).
The term polyvinyl halide used herein means polyvinyl
fluoride, polyvinyl chloride, polyvinylidene chloride
halogenated derivatives thereof and mixtures. These are
homopolymers or copolymers, and well known and commercially
available worldwide. Polyvinyl chloride polymers
conte~plated for use in the present invention include those
prepared in a variety of ways. PVC polymers can be
prepared by polymerization methods including: mass,
suspension, dispersion, and emulsion processes. A mass
process is described in U.S. Patent No. 3,522,227. A phase
inversion process may also be used and is disclosed in U.S.
Patent No. 3,706,722. A useful skinless, suspension PVC
resin is taught in U.S. Patent No. 4,711,908, in particular
example 4 in that disclosure. The preparation of porous,
skinless, crosslinked PVC resin can be prepared with the
25 direction of U.S. Patent No. 4,755,699, with particular
reference to example 1 of that disclosure. PVC resins used
herein are preferably those made by suspension or mass
processes. Suspension or mass PVC resins used herein are
- particulate homopolymer or rigid copolymer resin having a
30 particle size average ranging from ~bout 70 microns to 250
micron~.
-- 7 --
Suitable comonomers that vinyl fluoride and
polyvinylidene chloride may be included in minor amounts in
the vinyl chloride polymer(s) are the olefins, unsaturated
carboxylic acids such as acrylic acid, methacrylic acid,
ethacrylic acid, ~-cyanoacrylic acid, and the like; esters
of acrylic acid, for example, methyl acrylate, ethyl
acrylate, butyl acrylate, 2-ethylhexyl acrylate, octyl
acrylate, cyanoethyl acrylate, hydroxethyl acrylate and the
like; vinyl esters such as vinyl acetate and vinyl
propionate; esters of methacrylic acid, such as methyl
methacrylate, ethyl methacrylate, hydroxyethyl
methacrylate, butyl methacrylate, and the like; nitriles,
such as acrylonitrile and methacrylonitrile; acrylamides,
such as methyl acrylamide, N-methylol acrylamide, N-butoxy
1 15 methacrylamide, and the like; halogen containing vinyl
I monomers such as vinyl fluoride, vinylidene chloride, 1,2 -
dichoroethylene, vinylidene fluoride, vinylidene and vinyl
bromide; vinyl ethers such as ethylvinyl ether, chloroethyl
vinyl ether and the like; the vinyl ketones, styrene and
styrene derivatives including ~-methyl styrene, vinyl
toluene, chlorostyrene; vinyl naphthalene; cross-linking
monomers such as diallyl phthalate, trimethylol propane
triacrylate, allyl methacrylate and the like; allyl and
vinyl chloroacetate, vinyl pyridine, and methyl vinyl
ketone; and any copolymerizable monomers or mixtures of
monomers having suitable reactivity ratios with vinyl
chloride and known to those skilled in the art.
Particularly preferred are non-crosslinked polyvinyl
chloride homopolymer resins substantially free of gel
particles.
The inherent viscosity (I.V.) (ASTM D-1243) of
polyvinyl chloride used in this invention generally ranges
`~
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- 8 ~
from about 0.2 to about 4.0, with a preferred I.V. range of
from about 0.35 to about 1.2 and a more preferred I.V.
range of from about 0.5 to about 0.95. A combination of ~ -
PVC polymers each having a different average molecular
weight should be avoided to the extent that gloss is
significantly reduced. The more preferred I.V. range is
from 0.5 to 0.95, with the most preferred range from 0.52
to 0.80.
HDT modifiers may also be employed. These can be
copolymers comprising a monomer of the formula:
Rl--C = CH2
~ R2 (I)
[R3]X
wherein X is 0, or 1, the non-substituted ring carbons are
bonded to hydrogen, R1 is hydrogen, C1-C22 alkyl or halo
Cl-C22 alkyl; R2 and R3 are independently hydrogen, Cl-C22
alkyl, halo (Cl-C22) alkyl, or C1-C22 substituted alkyl.
The term copolymer refers generally to a polymer
containing two or more than two monomers, one of which is
defined by (I). Copolymers comprise (I) copolymerized with
other comonomers. Other comonomers include acrylates,
methacrylates, like methylmethacrylate (II), acrylonitrile
(III), methacrylonitrile, ~-chloroacrylonitrile,
ethacrylonitrile, anhydrides such as maleic anhydride, N- :
substituted maleimide and styrene (IV). A combination of
more than one species of I can be combined to comprise the
monomer composition of the HDT modifier. Specific examples
include a copolymer selected from the group consisting of
I/II, I/III, I/IV, I/II/III, I/II/IV, I/III/IV,
I/II/III/IV, and graft copolymers of either I/II, I/II/III,
~ .
I/II/IV, I/III, I/IV, I/III/IV graft polymerized on a
rubbery polydiene, polyacrylate; alpha olefin copolymer,
EPDM rubber, or butyl rubber or mixture thereof. Preferred
are copolymers containing from about 50% by weight to about
95% by weight of (I).
Polyimide HD~ modifiers for use herein include
polyimides, copolymers of vinyl aromatic and imide
derivatives of an ethylenic unsaturated dicarboxylic acid
such as a copolymer of alpha methyl styrene-styrene-N-
cyclohexyl maleimide, also included are imidized
polymethylmethacrylate, imidized styrene-maleic anhydride
copolymer, acrylic-imide copolymer, polyglutarimide,
polyitaconamide, and the like. Polyimide HDT modifiers
also include copolymers derived from a comonomer of N-
substituted maleimide expressed by the general formula:
1l
CH C
N -R
CH- C
~ 20 0
¦ wherein R is hydrogen, a non-substituted or substituted
hydrocarbon group, cyclic aliphatic hydrocarbon group or
aromatic hydrocarbon group, any of these having from 4 to
20 carbon atoms. Examples of R include t-butyl,
cyclohexyl, phenyl, 2-chlorophenyl, benzyl, 2-methyl
phenyl, 2-ethyl phenyl, 2,6-dichlorophenyl, 2,6-diethyl
phenyl, and the like. The most preferred imide HDT
modifiers are imidized polymethylmethacrylate. Examples of
the preparation o polyimides are described by Kopchik,
U.S. Patent No. 4,246,374, and Schroder, et al. U.S.
Patent No. 3,284,425. Imidized PMMA is commercially
av~ilable from the Rohm and ~aas Company under the trade
. .- ~,,
' ~
-- 10 --
names of Paraloid~ HT-510, Paraloid~ EXL-4151, Paraloid~
EXL-4171, Paraloid~ EXL-4241 and Paraloid~ EXL-4261. In
general, the degree of imidization can rànge from about 10
to 80 percent, preferably from 20 to about 60 percent.
Other heat distortion modifiers useful herein include
post chlorinated polyvinyl chloride, polycarbonate,
halogenated polycarbonate, polysulfones, polyesters, and
polyacrylates.
Generally, the PVC compounds herein will contain a
thermal stabilizer. The preferred thermal stabilizer
system emplcyed herewith is a combination of tin compound
and a co-stabilizer. The organotins are preferred tin
compounds and include dimethyl tin-bis
isooctylthioglycolate (methyltin), di-butyltin-bis-
isooctylthioglycolate (butyltin), octyltin-bis
isooctylthioglycolate, dialkyl tin di-carboxylates,
methyltin mercaptides, butyltin mercaptides, dialkyl tin
bis(alkyl mercaptocarboxylate) including di-n-octyltin-
S,S'-bis(isooctyl mercaptoacetate), and butylthiostannoic
acid, and mixtures thereof. Any alkylated tin having
features such as low toxicity e.g. higher alkyl types, FDA
approval, USP class 6 approval, good color, clarity and
compatibility, low plate-out on equipment, and non-staining
properties are desirable and preferred for use in this
invention. The more preferred stabilizer system of a tin
compound and epoxide co-stabilizer can contain any other
stabilizers such as derivatives of barium, cadmium, zinc,
antimony or lead containing heat stabilizers.
Co-stabilizers may be employed for example, phosphite
stabilizers, polymeric phosphites, thioesters such as
dilauryl thiodipropionate, beta-diketones and epoxy
derivatives. Co-stabilizer may be present at from 0.1 to
lo weight parts, preferably from 0.3 to about 5 phr, and
most preferably from 1.0 to 4.0 weight parts per 100 weight
parts combined of PVC and HDT modifier (phr). The
preferable costabilizer is an epoxy material.
Antioxidants are optionally present and include the
various hindered alkylated phenolics such as 2,6-di-t-
butyl-4-methyl phenol also referred to as butylated hydroxy
toluene, bis-phenols such as 2,2'-methylenebis(4-methyl-6-
t-butylphenol~, thio-phenols such as 4,4'-dihydroxydiphenyl
sulfide, otherwise referred to as thiodiphenol, and di-
phenyl ethers such as 4,4'-dihydroxydiphenyl ether, and
mixtures thereof. When used, antioxidants are generally
present in an amount from about 0.05 to 5 parts per hundred
weight parts PVC and pre~erably at from 0.1 to 1.0 phr.
Preferred antioxidants are those having acceptability under
applicable FDA regulations.
Polymeric impact modifiers may be present. Post-
chlorinated polyethylene is an exemplary po~ymeric impact
modifier. CPE is obtained from the chlorination of
polyethylene having a density (ASTM-D1505-57T) of from
about 0.91 to about 0.98 gram/cc. at 25C., a melting point
usually in the range of from about ~OO~C to 130C., and
melt index (according to ASTM-D1238-57T) above about 0.05,
more preferably in the range from about 0.05 to about 20.
A method of preparing such a CPE material is more fully
described in U.S. Patent 3,299,182. Suitable embodiments
are commercially available from Dow Chemical Inc., or E.I.
DuPont deNemours, Inc. CPE materials generally contain
from about 5% to about 50% wt. of combined chlorine. Those
- 12 -
containing from about 25% to about 40% wt. of combined
chlorine are preferred with PVC, and those containing from
about 32% to about 38% chlorine are most preferred.
The preferred impact modifier comprises an MBS type
optionally with an acrylic type. The principal embodiments
of MBS types are copolymers of methylmethacrylate,
butadiene, and styrene. Acrylonitrile may also be present
(MABS). Preferred impact modifiers generally contain a
rubbery core component, the particulars of this core being
beyond the scope of the invention. Various preferred core
embodiments include polymers derived from 1,3-butadiene,
isoprene, acrylates, olefins, styrene, or mixtures so long
as the core polymer exhibits a Tq of less than zero.
Preferably the Tg of the rubbery core polymer is below -
30C. The rubbery rore polymer is preferably present inthe polymerization of the shell comprising styrene and
! methyl methacrylate. Commercial embodiments of MBS include
Paraloid~ XM-653 and BTA-733 from Rohm and Haas, Inc., and
Kane-Ace~ B-56 and B-22 available from Kanegafuchi, Inc. A
combination of two acrylic impact modifiers, the minor
proportion being one containing a diene component and the
major proportion being one without a diene component is
most preferred. Both MBS and acrylic type polymeric impact
modifiers can also referred to as multi-stage polymers. A
commercially available diene containing acrylic is
~ Durastrength~ 200 from Atochem North America, Inc. Non-
!1' diene containing versions are Paraloid~ KM-330 or KM-334
from Rohm and Haas, Inc. The total amount of impact
modifier present is from 0 to 30 weight parts preferably
from 5 to less than 25 phr, and most preferably from lO to
about 20 phr. Total MBS and acrylic impact modifier are
-~ each present at
.,
..
,
;,
"A
';,~,
- 13 - ~ . J L~ ~ ~
preferably 0 to 15 phr, more preferably 4 to 12 phr, and
most preferably 5 to 10 phr.
The essential lubricants used in the present invention
comprise a long chain carboxylic acid, a metal salt of a
long chain carboxylic acid, an alkyl ester of an alkyl
polyol, and a hydrocarbon. The carboxylic acids include
C6-C24 carboxylic acids like undecylic acid, lauric acid,
myristic acid, palmitic acid, margaric acid, stearic acid,
oleic acid, ricinoleic acid, behenic acid, chlorocaproic
acid, hydroxy capric acid, hydroxy stearic acids and the
like. Preferred are Cl6-Cl8 carboxylic acids like stearic
acid.
The long chain carboxylic acids are employed at from 0.01
phr to about 10 phr, preferably the carboxylic acids are
employed at from 0.1 phr to about 5 phr, more preferably
from 0.2 to 2 phr and most preferably from 0.5 phr to
about 1.1 phr.
The metal salts of long chain aliphatic carboxylic
acids are sometimes referred to as metal carboxylate soaps. ~ -~
Metal carboxylate soaps include calcium, lithium, magnesium
and zinc salts of C8 to C30 carboxylic acids. The calcium
salts are preferred, with calcium salts of Cl6 to C18
carboxylic acids more preferred such as calcium stearate.
A metal carboxylate salt is preferably employed at from
0.01 to about 10 phr, preferably from 0.2 to 5 phr, more
preferably 0.5 to 2.5 phr, and most preferably from 1.0 to
2.0 phr.
The alkyl esters of alkyl polyols include glycol
esters and glycerol esters like ethylene glycol ester and
- 30 propylene glycol ester. Also included are oligomeric
3 ~ 3
glycol esters or oligo-glycerol esters. Specific examples
include glycerol mono 2-ethylhexanoate, diglycerol
monostearate, triglycerol mono stearate, a polyglycerol
ester of a C8 to C22 carboxylic acid such as hexaglycerol
5 mono stearate, hexaglycerol distearate, or any of the
glycerol, diglycerol, triglycerol or polyglycerol partial
esters of oleic acid. Preferred are the esters derived
from the reaction of glycerol and a C16 to C18 carboxylic
acid, with more preferred versions being mono-C16 to C18
10 esters of glycerol such as glycerol monostearate (GMS).
The esters of alkyl polyols are available commercially from
Henkel Int., Inc. The alkyl polyol esters are employed at
from 0.1 phr to 10 phr generally, preferably from 0.2 to 5,
more preferably from 0.3 to 2.0 phr and most preferably
15 from 0.5 to 1.3 phr.
The hydrocarbon or derivative of hydrocarbon used
herein in combination with other components include
paraffins such as paraffin oils and mineral oils,
microcrystalline wax, paraffin wax, and low molecular
20 weight polyolefin such as polyethylene wax, either in
liquid, powder or flakes. These are commercially available
from Sonneborn Division of Witco Chem. Co., Inc., Penreco
Inc., Union Oil Co., Inc., and Frank B. Cross, Co., Inc
Mineral oil is the preferred hydrocarbon. The hydrocarbon
25 is employed at from 0.1 to 10 phr, preferably 0.2 to 5 phr,
more preferably from 0.5 to 3 phr and most preferably from
1.0 to 2.0 phr.
Optional lubricating components include epoxide
materials like epoxidized oils, epoxidized linseed oil,
30 epoxidized tall oil, epoxidized soy oil, and epoxy
derivatives of bisphenol A, for example, the reaction
3 . .:
- 15 - -
product of epichlorohydrin and bisphenol-A. Generally as
liquids or meltable solids, epoxy materials include
dig~lycidylether of bisphenol A, having molecular weight
above about 370. A variety of commercial sources for
epoxy containing materials is listed in Chemical Week
Buyers' Guide, October, 1990. Epoxy resins are availablP
under the Epon~ trademark of Shell Chemical Co., Inc. The
most preferred epoxide containing materials are the
epoxidized oils like epoxidized soybean oil (ESO) and
epoxidized linseed oil. The epoxy materials are used at
from O.1 to 10 phr, more preferably at 1 to 6 phr and most
preferably at from 1 to 4 phr.
The chemically modified waxes and mineral waxes are
most preferably avoided. These include montan wax, and
montan ester waxes which may be mixtures of long chain
acids, long chain esters and resinous portions. Reference
i5 made to Kirk-Othmer Encvclopedia of Chemical TechnolooY,
Wiley Interscience, Vol. 23, 1978, Pg. 471. Montan ester
wax is available from Hoechst-Celanese Inc.
. ~
The above specified ranges of amounts of each
component in the invention is expressed in terms of weight
parts of the component per 100 weight parts of PVC (phr).
The range of optional lubricant components is the same as
specified above.
There is an optimal total amount of lubricant beyond
which there are negative effects on HDT and impact
strength. Generally the lubricant system compri6es a total
~ of about 1 to 10 phr of the above components, preferably
??1 from 3 to about 8 phr total and more preferably from about
~ 30 3.5 up to 7 phr and most preferably from about 3.5 to about
~? : .
" ' '~
?,,ijG . ., ~
J ~
- 16 -
6.2 phr. The precise total amount of lubricant desired
will depend on *he I.V. of the PVC present. Generally, a
lesser total amount of lubricant is required when
lubricating a PVC having an I.Y. less than about 0.6.
Whereas, when lubricating a PVC of I.V. 0.6 or higher,
relatively higher amounts of lubricating ingredients are
suggested. Several combinations are suggested herein
within practical ranges. Optimization of particular
individual formulations is beyond the scope of the present
invention, and can be achieved by one skilled in the art
after reasonable trial and error.
At least one optional plasticizer may be included in a
minor amount ranging from 0.1 t~ about 10 phr, preferably
from 1 to 5 phr, the upper limit otherwise controlled by
not allowing the flexural modulus to drop below 100,000
psi. Specific examples of plasticizers include carboxylic
acid esters such as the various esters of adipic acid,
azelaic acid, phthalic acid, benzoic acid, citric acid,
isobutyric acid, isophthalic acid, sebacic acid, isosebacic
acid, stearic acid, tartaric acid, oleic acid, succinic
acid, phosphori~ acid, terephthalic acid, trimellitic
acid, and mixtures. Other plasticizers include for
example, partial esters of the above carboxylic acids,
ethers, glycol and pentaerythritol derivatives, glycolates
and glycerol derivatives. These are set forth in The
Technoloav of Plasticizers, by Sears and Darby, pages 893-
1085, John Wiley & Sons, New York, 1982. Preferred
plasticizers are C4 and higher alkyl diesters of phthalic
acid, such as di-2-ethylhexyl phthalate, and di-
3C isodecylphthalate bisphthalates, C8 and higher alkyltriesters of trimellitic acid such as tri-octyltrimellitate
(TOTM). Various polymeric plasticizers can also be
utilized such as the polyesters, polyolefins,
polyepichlorohydrins, polya¢rylates, ethylene copolymers,
and copolymers prepared from di- and monoolefins.
Polyester plasticizers are generally made from a
dicarboxylic acid having from about 3 to about 12 carbon
atoms and from a diol having from about 2 to about lOOO ~-
carbon atoms with propylene glycol being preferred.
Examples of suitable polyesters include various esters made
from adipic acid such as a polyester having a molecular
weight of 6,000, e.g., Paraplex0 G-40, a polyester made
from adipic acid having a molecular weight of about 2,200,
Paraplex0 G-50, a polyester made from adipic acid having a
molecular weight of about 3,300, Paraplex0 G-54, a
polyester made from azelaic acid having a molecular weight
of about 2,200, Plastolein0 975, a polyester made from
sebacic acid such as Paraplex0 G-25, a polyester made from
glutaric acid, a polycaprolactone polyester, and the like.
Paraplex is a trademark of C.P. Hall Co. and Plastolein i8 -
a trademark of Emery Industries, Inc. Plasticizer is
preferably avoided to achieve higher HDT. For semi-rigid -~
compound a small a~ount is preferred.
:' ~
The PVC compounds disclosed herein will typically
contain optional additives such as: pigments, blowing
agents, coupling agents, processing aids, fillers,
antistatic agents, anti-fogging agents, flame retardants,
smoke suppressants, colorants all of which are commercially
available and partially listed in Modern Plastics ~ -;
EncycloDedia 1988 published by McGraw Hill Co. ~-
Exemplary antistats are commercially available under
the Glycolube0 trademark of Lonza Corp. An exemplary
~:
::
- 18 ~
antifogging agent includes the alkyl phenol ethoxylates as
for example those commercially available under the Surfonic
trademark of Texaco, Inc~
Adjustment of melt viscosity can be achieved as well
as increasing melt strength by employing process aids such
as those containing polyacrylates. It has been found that
these do not interfere with gloss at useful levels.
Exemplary processing aids are copolymers of
polymethylmethacrylate. Paraloid~ X-120ND, K-120N, K-175
from Rohm and Haas, Inc. are a few examples. Reference to
others is found in The Plastics and Rubber Institute:
International Conference on PVC PrQcessin~, April 26-28
(1983), Paper No. 17.
Fillers are optional and include clay, barytes,
calcium carbonate, talc, mica, silica, aluminum trihydrate,
dolomite and fiber reinforcement such as carbon, glass and
boron fibers. Where used, calcium carbonate which has a
particle sizes average of from 0.02 to 1.0 micron,
preferably 0.02 to 1.0 micron and is treated with from
~ about 1% to 5% by weight of fatty acid is preferred. The
¦ precipitated calcium carbonates having these features are
available from Pfizer Minerals, Inc. under the Ultraflex~
trademark. Preferable levels of fillers are 0 to 10 phr,
more preferably 0 to 5 phr, and most preferably zero.
Exemplary opacifying pigments include titanium
dioxide, preferably rutile grades. Rutile grades can be
- surface coated with ingredients such as silica, zirconia,
alumina, or other minerals, including combinations of
these. The extent of coating is in a range of fro~ about
2% to about 99% surface ~rea coverage. Zinc co~ted ~iO2
,~ ~
~;
-- 19 --
should be avoided as it induces degradation with PVC. An -
example of uncoated Tio2 is designated R-100 from E.I.
DuPont de Nemours. An example of lightly coated Tio2 is
Tioxide~ RFC-6 from Tioxide of Canada Ltd. and contains a
combination of zirconia and silica coatings. More
preferred Tio2 grades are coated, for example, with from 90
% to 99.99 % of the surface covered with silica may also be
used. Commercial versions include Tipure0R-960 from E.I.
DuPont de Nemours, Inc., and Zopaque0 RCL-6 from SCM
Corporation.
The impact performance levels preferred are a room
temperature notched IZOD of at least above about 2 ft.-
lbs/in. (of notch) and more preferably at least 4 ft.-
lbs./in. The Preferred notched Izod impact properties at -
40 achieved were greater than 1.0 ft.-lbs./in. and more
preferred embodiments greater than 2 ft.-lbs./in. The
most preferred embodiments achieved a notched Izod at -40~C
of greater than 4 ft.-lbs./in. of notched, with some
examples below having greater than 6 ft.-lbs./in. of notch.
The preferred compositions exhibited a Brabender dynamic -
thermal stability time at 200C and 50 rpm with a No. 5
mixing head of at least 20 minutes with the more preferred
embodiments exhibiting a DTS time of 25 or more minutes and
the most preferred embodiments achieved a DTS time of 30
minutes or more. Compounds of the present invention in the
fused state exhibit an HDT at 66 psi of at least 58C, more
preferably 60C and most preferably at least 64C. It is
possible with the compositions to include an amount of heat
distortion modifier to raise the HDT preferably at least
3C higher. Useful HDT modifiers including the
aforementioned copolymers of alpha methyl styrene, styrene-
acrylonitrile copolymers, imidized acrylic polymer,
polycarbonate, halogenated polycarbonate, styrene maleic
r~
~ 20 ~
anhydride copolymers, and the like may be employed to raise
HDT.
The invention will be better appreciated by the
following examples in which comparisons are made between
examples not a subject of this invention with those which
exemplify the improvements of this invention. All amounts
of ingredients are shown in weight parts. The following
ASTM test procedures were used in evaluation the
performan¢e parameters measured.
Pro~erty Test
Notched IZOD Impact Strength ASTM-D256
Heat Distortion ~emp.* ASTM-D648
Inherent Viscosity ASTM-D1243
Dynamic Thermal Stability Brabender Plasticorder~
(DTS)
Gloss at 60 Glossgard0 II glossmeter
A~ 66 F6i on unanncalcd compre~sion molded plaques
: '
The compounds of the present invention can be utilized
in melt forming processes such as, for example, injection
molding, extrusion, co-extrusion, thermoforming,
lamination, compression molding, calendering, and the like,
including uses for a capping layer in a co-extr~sion or
lamination of sheet or profile such as a capping layer on a
substrate in the form of a layer of the compound in the
fused state in intimate contact with a substrate selected
from the group consisting of metal, wood, a thermoset
article, and a thermoplastic article.
Specific articles derived from the invention include
sheeting for thermoforming of shower stalls, wall panels,
bathtubs, tub enclosures, refrigerator panels cabinetry and
'.,,
'~ 8
- 21 -
the like, doors, vertical and horizontal blinds, sporting
equipment, automotive components, appliance components,
components used in molded parts for boats, housewares,
plumbing ware, signs and business machine housings. Thus,
the present invention has extended the useful range of
applications for polyvinyl halide-based thermoplastic
articles where the improved combination of properties are
needed and where it is desirable to combine the compo~nd
with a substrate for improved asthetics and economy.
The DTS test measures the time-torque relationship at
selected temperatures using an instrument such as the
Brabender Plasticorder0. Model EPL-V30Z is a suitable
model. The test value generally reported and u.sed for
comparison is the 'IDTS time". DTS time is defined as the -
time elapsed from the time the rotors are turned on in the
presence of the sample, including the time the instrument
torque falls to its minimum value, up to the point where
torque has risen about 50 to lO0 meter-grams from the
minimum. This time is limited by the stability limits of
the composition under shear. DTS time is dependent on
inherent polymer properties, but also on temperature,
sample ~ize, compound formulation, instrument operating
conditions, degree of instrument maintenance, and other
conditions. In the examples below, DTS was run using a no.
5 mixing head, with a bowl temperature of 400F, other
conditions controlled to provide for accurate comparisons.
The preferred compounds of this invention surprisingly gave
a DTS time at 400F (204 C) of at least 20 minutes, more
preferred embodiments gave 25 minutes or higher. This was
achieved while at the same time, the preferred compounds
exhibited excellent impact strength. The occurrence of a
- boost in both gloss and impact strength properties was
- ~.
',3
- 22 -
unexpected and defied the expected trend based on the
conventional understanding of lubrication interferences
with impact strength achievement.
VARIABLE HEIGHT IMPACT STRENGTH
Variable Height Impact Test. A weight (typically 8
lbs.) is placed in a cylindrical tube and a conical dart
(typically with a 1/8" diameter tip) is attached to the
bottom of the weight. The sample is placed below the
cylinder and the weight with dart attached is dropped,
while contained by the cylinder, onto the sample. The
height of the weight is increased until the dart puncture
area show a failure ttypically when a crack appears in the
impacted area and light can be clearly seen through the
crack). The height of the weight is then lowered
incrementally until the impacted points pass the test (when
no crack through which light can be seen is made). The
height is then increased again until a failure occurs and
I then decreased until a pass occurs. Typically 9 to 16
¦ impacts are made per test. The height (of the dart above
the sample) at which 50% of the time a pass occurs is taken
as the value to be used to calculate the average impact
strength. This value is the weight times the height and is
usually reported in inch-pounds. The inch-pounds are then
divided by the average thickness of the sample (here
approximately 20 mils. a mil = 0.001 inch~ and the final
value is reported as inch-pounds per mil.
- I.V. - INHERENT VISCOSITY (ASTM-D1243)
The inherent viscosity is measured for PVC using
cyclohexanone as the solvent. The polymer is dissolved in
~ ' ' :
~j
~1 .
2 ~
- 23 -
the solvent at a concentration of 0.2 gram per 100 mls. of
cyclohexanone at 90C for 90 minutes and then measured with
a viscometer in a water bath at 30C.
EXAMPLES 1-31
S The compounds listed in table A below were prepared by
hand mixing the components in a Henschel high intensity
powder mixer to form a uniform powder blend. The powder
blend was banded on a heated r~ll mill until well fused.
The temperature of the material on the mill was
approximately 379F. Sheets were removed from the mill and
compression molded into plaques used for physical testing.
A portion of the sheets taken from the mill were also cubed
~ and cubes were used for measurement of DTS. The cubes were
¦ extruded on a laboratory sized Brabender extruder using a
4 " X 0.020 " strip die to prepare samples for 60 gloss
measurement and VHIT testing. In each compound 100 weight
parts of polyvinyl chloride homopolymer having an I.V. of
0.68 was used. Two weight parts of tin stabilizer and -
eight parts acrylic impact modifier stabilizer (2 parts of
one containing a diene component and 6 parts of one absent
a diene component) was included in each example except for
~ example 22 which contained only two parts of acrylic impact
3 modifier. The remaining components in each example are
listed in table A on the basis of weight parts. Table B
illustrates the properties obtained from the compression
~ molded plaques made from the milled sheets. A least two
c gloss measurements were obtained from each extruded 4" wide
strip and averaged if different. Gloss measurements were
;~ obtained at 60 using a Gardner Glossgard II gloss meter
supplied from Pacific Scientific, Inc. The gloss readings
using this method and taken directly from the extruded
.,
. . .
';`
. j; . .
~la~
- 24 -
compounds with out further polishing yield preferably a
gloss of at least 40%, more preferably 50% and most
preferably greater than 55~ for the compounds of the
invention.
JS-,t 6~ ~
~ --o-o E -o -o -o -o =o ~ ~ ~:
_ N _ O _ O _ O ___ ~t
~r N O O _ 10 O _ O O In
~ ~I tq O O Y~ 0 0 o o In O .,
N N _ It) _ O O _ O O 't
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~ ~ o ~ _ o 0 _ o o r B
~ ¦ N _ 0 _ _ O _ O O ~ r~
O r~ lo _ Il~ O 0 O O ~r o~
_ _ _ _ _ _ _ _ _ _ :,~:,.
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~, L~ ~ ~ o u o ~ o o t ~ ;~
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N N _ O O O O _ O _ 0 O N
_ _ _ _ _ _ _ _ _ _ _ _
æ _ O ~ O O O 0 O O ~ O 0
N N ; O _ IO 0 0 O O 0 O ~3
Z N N O _ _ _ O 0 O O ~ O C~
N I_ _ _ _ 0 0 O O O ~ O .
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æ L~ O O O u~ O 0 O O u~ O ~
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r1~ 2 0 _ _ t-~ ~1 _ ~ 1~ O _ O _ ~
L~ ~ 0 ~ ~ 0 æ ~ N 1~ ~-~I I~D _ 8 0 ~
E 3 N C~ _ 8~ æ N ~ O _ 8 _ ¦
E ~ ~ o ~ æ ~O ~ ~ N _ ~ I .
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- 28 -
It can be seen from table A the effect on gloss of the
lubricant system. Example 1 contains a combination of
acrylic and MBS impact modifier and a preferred lubricant
system containing ES0, Ca stearate, GMS, mineral oil and
stearic acid. The gloss is high at 58.6. Example 6
confirms the high glo55 using this system. Example 1 was
extruded on a sheet extrusion device. The sheet was
measured for initial gloss before thermoforming. The draw
ratio of initial to drawn thickness was 2:1. There was ~ -~
lo surprisingly no loss in gloss measured at the region which
was drawn at the 2:1 ratio.
In commercial practices of sheet forming, typically a
polishing stack is used and gloss is enhanced to a level of
greater than 70 and preferably qreater than 80. The
lS preferred embodiments of the invention can be polished in
this manner and will typically exhibit a gloss of 80 or
I higher and will lose less than 10% of the initial polished
¦ gloss when drawn at least 2:1 during thermofor~ing. It is
recognized in the art that one can expect at least a 20%
gloss reduction after thermoforming. In one thermoforming
run the compound in sheet form was polished to a gloss of
85. A 145 mil sheet was drawn by thermofor~ing. Quite
unexpectedly, the gloss measured at a point having
thickness of 70-75 mils, correspondinq to a 2:1 draw ratio,
was 85.
Example 2 illustrates the loss of some gloss by
~ eliminating ES0; example 3 shows reduction in gloss on
3 elimination of mineral oil; example 4 shows reduction in
3 gloss on elimination of Ca stearate; example 5 with GMS
(ester of polyol) eliminated, a likewise reduction; example
7 is absent carboxylic acid and gloss is reduced; example 8
., ~
':
' -:
,;,
ib ~ L;~
-- 29 --
is absent both ESO and mineral oil, however noting in table
B that DTS is reduced to 21 minutes and gloss was lower
than example one. Higher DTS is preferred. Example 9
illustrates a gain in DTS on addition of ESO.
Gloss is reduced on elimination of GMS and mineral oil
as example 10 illustrates. Elimination of both ES0 and GMS
in example 11 shows reduced gloss and significantly lower
DTS (19 min.). Elimination of mineral oil and stearic acid
caused reduced gloss and reduced -40c Izod as shown in
example 12. Gloss ranged from about 36 to about 44 for
examples 13-16 wherein calcium stearate and at least one
other preferred lubricant was eliminated. The use of ES0
shows in examples 13 and 15 versus 14 and 16 a recovery in
DTS, however, low temperature impact is not as good without
carboxylate salt. Gloss is also reduced in example 17
when GMS and mineral oil are absent.
Example 23 illustrates that high gloss can be obtained
(64.5) with the elimination of MBS impact modifier, however
it is noted the drastic lowering of -40C Izod impact.
3 . ~
- 30 -
Example 22 illustrates the elimination of the six
parts of acrylic impact modifier and is comparable to
example 1 which contains eight parts of acrylic impact
modifier. The same lubrication system is used however,
example 22 has lower gloss and significantly lower -40C
impact.
Examples 19, 20 and 21 have no polyol ester, no
carboxylate salt and no ESO. Examples 20 and 21 have only
one component of lubricant system, namely, mineral oil, and
stearic acid, respectively. The gloss is reduced and -40C
impact is low. Examples 19-21 have unacceptable DTS times
of 13, 14 and 9.5 minutes.
Examples 24 - 28 illustrate poor DTS time when at
¦ least one lubricant of the invention is missing, as well as
~ 15 the negative effects on gloss and -40C Izod.
I
Example 30 is comparable to example 1 to show the
significant loss in gloss with the use of montan wax which
is a mineral wax. Example 30 had a 37.4 gloss rating with
the use of 1.0 phr montan wax, but the gloss rating
~ 20 increased when montan wax was eliminated and stearic acid
¦ was used in a preferred amount.
The data of example 31 shows that there is obtained,
good gloss with the use of a relatively higher level of GMS
and carboxylic acid, however this leads to reduced -40C
impact strength.
.-:
Example 29 is comparable with example 1 except for the
use of 10 phr CaCO3 filler. The data shows that DTS, glo~s
','~'~ '-; :
. "~
~:
,,:
C~
- 31 -
and notched Izod impact strength are reduced with the use
of filler.
5~, . : , , . , '''' :,,: ,~,' ': '' '' , : ', '
- 32 -
B~amples 32- 7
The examples below illustrate the effect on gloss of
various Tio2 embodiments. These compounds listed in table
C were prepared similarly to the previous examples except
for hand mixing of the powder compound. The following base
compound is included in Examples 32-37:
PVC (I.V. 0.68)100
Acrylic Process aid 2
Acrylic Impact Modifier 2 *
Stabilizer 2
ESO 8
Ca Stearate 1.5
GMS
Mineral Oil 1.5
Stearic Acid 0.8
* DurastrengthR 200, ex. Atochemie
- 33 -
,
., In addition to the above weight parts of ingredients,
Examples 32-37 contain the following:
EXANPL~
~BLE C ~ 9
32 33 34 35 36 37
I
Acrylic Impact Mod~ - 6
Acrylic Impact Mod2 6 6 6 6 6
, MBS Impact Mod. (A)3 8 8 ~ 8 8 8
il MBS Impact Mod.(B)4 - - 8
Tio2 (A) 5 4.5 - 4.5 _ _ 4.5
Tio2 (B) 6 - 4.5 - - - - ~
Tio2 (C) 7 - - - 4.5
Tio2 (D) 8 - _ _ _ 4.5
1 RM-334 ex. Rohm and Haas, Inc.
2 KM-330 ex. Rohm and Haa~, Inc.
3 KM-653 ex. Rolun and ~3aas, Irlc.
4 BTA-733 ex. Rohm and Haa~, Inc.
5 uncoated TiO : ~-100, ex. DuPont
6 non-chalking, coated TiO : R-FC-6, ex. Tioxide of Canada
7 non-chalking, coated Tio: R-960 ex. DuPont
8 non-chalking, coated TiO : 2CL-6 ex. SCM Chemical
The above compou~ds were measured for 60 gloss with
the following results:
~xample
32 33 . 34 35 36 37
60 gloss 79.9 80.6 80.1 87. 3 86.1 82.1
DTS (Min) 33.5 36.5 34.5 35 33 32
~'
:~
,~
2 ~
- 34 -
The above examples 32-37 also exhibited an HDT at 66
psi of at least 66C, and room temperature notched Izod
impact strength of at least 16 ft.-lbs./in.
Noting the above gloss measurements, it can now be
appreciated that the above compounds have a good balance of
desirable properties. Especially good gloss was obtained
with the use of heavily coated Tio2 and is preferred.
