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BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to clay filled blends and more specifically, it
relates to clay filled blends of ethylene/vinyl ester copolymers modified
with processing oil.
2. Description of the Prior Art
Use of fillers in compounding of adhesives, coatings, mastics, etc. is old
art. Generally, the use of fillers contributes stiffness and resistance to
elevated temperatures for blends. In addition, fillers increase the
density of the blend; and, because most fillers are far less costly than
resinous binders, the final filled blends are significantly less costly
than are the unfilled precursors.
Clay is a useful filler for many resin-based blends because it is low in
cost and can readily be blended in conventional equipment. However, blends
which contain both ethylene/vinyl acetate (EVA) copolymer and clay at
elevated temperatures often rapidly decompose and liberate copious
quantities of anhydrous acetic acid (HAc).
Schwartz U.S. Pat. No. 3,904,456 is related to a method for inhibiting
transmission of airborne noise by interposing in the air space between the
noise source and the location to be insulated a thin, dense normally
self-supporting film or sheet composed essentially of from about 10 to
about 40% by weight of ethylene/vinyl acetate copolymer having an average
vinyl acetate content of from about 10 to about 42% by weight and a glass
transition temperature of at least about 30.degree. C. below the average
ambient temperature in the air space, and from about 60 to about 90% by
weight of inorganic filler materials, such as sulfates, carbonates,
oxides, etc. of barium, calcium, cadmium, etc., effective to produce an
overall density greater than at least 2 grams per cubic centimeter.
EVA copolymers have been used industrially for nearly two decades, however,
they are not known to be used in conjunction with processing oils as
articles of commerce. This could well be an outgrowth of the way EVA
commercialization has proceeded. That is, most EVA blends are based on
EVA/paraffin wax technology, where paraffin wax weight is often up to ten
times the weight of the EVA present. Furthermore, despite the obvious
savings inherent in using lower-cost, lower-quality waxes, such as scale
wax or slack wax, all attempts to do this have failed. The reason was
always the same--the oil content of the wax migrated and destroyed the
effectiveness of the coating or adhesive when the oil reached the bond or
sheet surface. Thus, compounders "knew" that oil could not be used in EVA
blends and technology developed along other lines.
Rundle U.S. Pat. No. 3,497,375 discloses coating compositions for wooden
concrete molds consisting of ethylene/vinyl acetate copolymer and
paraffinic oil. There is no filler employed in the coating compositions of
this patent.
Monaghan U.S. Pat. No. 3,379,193 discloses teeth covers made of
ethylene-vinyl acetate copolymer in itself or in combination with mineral
oil and, if desired, with fibers and coloring materials. The preferred
formulation is disclosed to be 47% by weight of ethylene-vinyl acetate
copolymer, 47% by weight of mineral oil, 5% by weight of nylon fibers, and
1% by weight of titanium dioxide.
German Patent Application No. 2,319,431 discloses sound deadening
composites suitable for use in automobiles which consist of a highly
filled polymer sheet (for example, 300-1200 or even up to 1500 parts of
filler per 100 parts of polymer) which on its backside is provided with a
filler material sheet, e.g., a polymer foam. Suitable polymers for use are
disclosed to be terpolymers of ethylene, propylene and a non-conjugated
diene (EPDM), polyvinyl chloride (PVC), mixed polymers of ethylene and
vinyl acetate (EVA), styrene-butadiene mixed polymers (SBR) and mixtures
of these materials with thermoplastic polymers, such as polystyrene and
polyolefins.
Boyer U.S. Pat. No. 3,010,899 discloses blends of ethylene/vinyl acetate
resin and mineral oil which are either rubbery or grease like depending
upon the proportion of oil to resin and can be used as a substitute for
crepe rubber or as a grease. It is further disclosed that fillers such as
carbon black or finely divided clays can be added to the rubbery products
to increase hardness and produce materials suitable as floor tile. As
indicated for example in claim 11, the filler, carbon black, is present in
a "minor amount" while the oil-ethylene/vinyl acetate copolymer mixture is
present in a "major amount". In Example 2 an oil+resin/carbon black ratio
of 4 parts by weight to 1 part by weight is indicated.
Rosenfelder U.S. Pat. No. 3,203,921 discloses the use of compositions
consisting essentially of 73-88% by weight of a homo- or copolymer of
ethylene (which can be ethylene/vinyl acetate or ethylene/ethyl acrylate
copolymer), 2-7% by weight of an aliphatic paraffinic hydrocarbon mineral
oil and 10-20% by weight of a mineral filler, (for example, calcium
carbonate, barium sulfate, etc.) for preparing blow-molded objects such as
dolls.
SUMMARY OF THE INVENTION
According to the present invention there is provided a composition
consisting essentially of (a) from about 5 to about 50% by weight of clay;
(b) processing oil in an amount that the weight ratio of oil:clay is at
least about 1:4 (c) from about 5 to about 50% by weight of at least one
copolymer of ethylene with at least one comonomer selected from the group
consisting of vinyl esters of saturated carboxylic acids wherein the acid
moiety has up to 4 carbon atoms, the ethylene content of said copolymer
being from about 60 to about 90% by weight, the vinyl ester comonomer
content of said copolymer being from about 10 to about 40% by weight, said
copolymer optionally containing from 0 to about 30% by weight of
additional comonomer selected from the group consisting of unsaturated
mono- or dicarboxylic acids of 3 to 5 carbon atoms and esters of said
unsaturated mono- or dicarboxylic acids wherein the alcohol moiety has 1
to 8 carbon atoms, carbon monoxide and sulfur dioxide, and the melt index
of said copolymer being from about 0.1 to about 500; and (d) from 0 to
about 90% by weight of inert organic or filler additive.
In the context of the present invention the terms "inert organic additive"
and "inert filler additive" means that such organic additive does not
react with the clay ingredient of the present composition and that the
inert filler additive does not react with the ethylene/vinyl ester
copolymer ingredient of the present composition.
DETAILED DESCRIPTION OF THE INVENTION
A highly effective way was discovered to enable the use of substantial
amounts of clay in EVA blends. It consists of pretreating the clay or a
clay/Whiting (naturally occurring ground limestone, CaCO.sub.3, from
Georgia Marble Company) blend with a processing oil, prior to addition of
the EVA and fluxing the mixture. Thus, two steps are involved:
(1) It is necessary to add oil to blends to passivate the clay.
(2) Proper sequencing is necessary to attain success in the mixing
operation when complex mixtures are made; that is, use of Sequence A,
below, during intensive mixing will be successful; while Sequence B may
fail, if the EVA/clay mixture is heated before the clay is passivated:
Sequence A: "X"--Clay--"Y"--Oil--Mix--EVA--Mix.
Sequence B: "X"--Clay--EVA--Mix--Oil--"Y"--Mix.
In the above illustration, "X" and "Y" may be either nothing or other inert
fillers or diluents or resins which do not influence the otherwise
probable adverse reaction of EVA with untreated clay.
The ethylene copolymers suitable for the composition of the present
invention are copolymers with at least one comonomer selected from the
group consisting of vinyl esters of saturated carboxylic acids wherein the
acid moiety has up to 4 carbon atoms. Thus, terpolymers of ethylene and
the above comonomers are also suitable. In addition terpolymers of
ethylene/vinyl ester and up to about 30% by weight of a third comonomer
selected from the group consisting of unsaturated mono- or dicarboxylic
acids of 3 to 5 carbon atoms and esters of said unsaturated mono- or
dicarboxylic acids wherein the alcohol moiety has 1 to 8 carbon atoms,
carbon monoxide and sulfur dioxide can also be employed.
The ethylene content of the copolymer is from about 60 to about 90%,
preferably from about 65 to about 85% by weight and the comonomer content
is from about 10 to about 40%, preferably from about 15 to about 35% by
weight. A mixture of two or more ethylene/vinyl ester copolymers can be
used in the blends of the present invention in place of a single copolymer
as long as the average values for the comonomer content will be within the
above indicated range.
Employing a copolymer containing over 28% non-ethylenic comonomer (such as
vinyl acetate) results in blends that are less stiff and have lower
tensile strength, while their elongation is increased. The most preferred
level is about 18 to 28 weight percent. Below 18% vinyl acetate, the
blends become much stiffer, lose elongation, and oil compatibility
problems arise. Even blends made with nonbleeding oils become "oily" as
polyethylene homopolymer is approached.
Melt index of the copolymer can range from about 0.1 to about 500,
preferably from about 0.1 to about 50.
Physical properties, principally elongation, decline to lower levels when
the ethylene copolymer melt index is above about 30. Lower melt index
ranges, about 1 to 10, are most preferred to maintain strength.
Generally from about 5 to about 50% by weight of the ethylene/vinyl ester
copolymer is employed in the composition of the present invention,
preferably from about 5 to about 40% by weight, and most preferably from
about 10 to about 40% by weight.
In accordance with the above, suitable ethylene/vinyl ester copolymers are
such as ethylene/vinyl acetate, ethylene/vinyl acetate/acrylic acid,
ethylene/vinyl acetate/methacrylic acid, ethylene/vinyl acetate/carbon
monoxide/ and ethylene/vinyl acetate/sulfur dioxide. Particularly suitable
copolymers are ethylene/vinyl acetate, ethylene/vinyl acetate/methacrylic
acid and ethylene/vinyl acetate/carbonmonoxide copolymers.
The oil ingredient of the composition of the present invention is known as
processing oil. Three types of processing oils are known-paraffinic,
aromatic and naphthenic. None of these are pure, the designations identify
the major oil type present.
Paraffinic oils tend to "bleed" from blends. Bleeding is normally not
desirable, but could be useful in specialty applications, for example, in
concrete forms where mold release characteristics are valued.
On the other hand, naphthenic and aromatic oils are non-bleeding when used
in proper ratios and are thus preferable for uses such as automotive
carpet backsize.
Processing oils are also subdivided by viscosity range. "Thin" oils can be
as low as 100-500 SUS (Saybolt Universal Seconds) at 100.degree. F.
(38.degree. C.). "Heavy" oils can be as high as 6000 SUS at 100.degree. F.
(38.degree. C.).
A processing oil is the key ingredient required for passivation of clay in
simple blends based on the EVA, clay, and inert fillers. The capacity of a
given amount of oils in passivation of clay is limited. Thus, while a 3:1
clay-oil blend can be mixed without difficulty, a 4:1 blend shows signs of
EVA decomposition. Accordingly the amount of oil present in the
compositions of the present invention should be such that the weight ratio
of oil:clay is at least about 1:4. For certain applications up to about
30% by weight of oil can be employed in the composition of the present
invention.
Table A summarizes the composition, properties and origin of various
processing oils.
TABLE A
__________________________________________________________________________
CLASSIFICATION AND CHARACTERISTICS OF PROCESSING OILS
CARBON
VISCOSITY
ATOMS
ASTM SUS.sup.(2)
% MOL.
TRADE NAME
TYPE
TYPE
SP. GR
100.degree. F.
210.degree. F.
C.sub.A
C.sub.N
C.sub.P
WT..sup.(3)
__________________________________________________________________________
"CIRCOSOL"
4240 N 103 0.95
2525
87 21
39
40
395
"CIRCOSOL"
5600 N 103 0.95
5945
135 20
38
42
450
"CIRCOSOL"
450 N 103 0.94
515
52 21
37
42
355
"SUNPAR"
150 P 104 B
0.88
500
64 4
27
69
530
"SUNPAR"
2280 P 104 B
0.89
2907
155 4
25
71
720
"SUNDEX"
790 A 102 0.98
3500
85.7
37
28
35
375
"SUNDEX"
8600T A 101 0.98
-- 300 30
22
48
--
"SUNTHANE"
450 N 103 0.93
502
52 15
43
42
355
"SUNTHANE"
4240 N 103 0.88
2206
85 18
41
41
400
"FLEXON"
340 A 102 0.95
130
38.7
31
41
28
"FLEXON"
766 N 104 A
0.90
503
58.2
1
45
54
"FLEXON"
865 P 104 B
0.87
332
43-61
4
27
69
"FLEXON"
815 P 104 B
0.90
2650
155 2
32
66
"FLEXON"
676 N 103 0.93
1200
72 15
40
45
"FLEXON"
391 A 102 0.98
4010
92 28
43
29
"TUFFLO"
60 P -- 0.88
600
68 4
26
70
550
"TUFFLO"
80 P 0.90
2640
155 4
23
73
720
"TUFFLO"
500.sup.(4)
N 0.94
518
52 22
36
42
355
"TUFFLO"
2000.sup.(4)
N 0.95
2150
82 20
39
41
390
"TUFFLO"
491.sup.(5)
A 0.99
7060
128 40
20
40
425
"TUFFLO"
2000.sup.(5)
N 0.93
2110
97 12
38
50
460
"TUFFLO"
6024.sup.(5)
N 0.89
175
43 1
50
49
345
"TUFFLO"
6204 N 0.91
1750
91 2
49
49
__________________________________________________________________________
.sup.(1) A = aromatic; N = naphthenic P = paraffinic. As classified by
supplier
.sup.(2) SUS = Saybolt Universal Seconds .congruent. 5 .times. Viscosity
in centipoise (cp)
.sup.(3) as provided by supplier
.sup.(4) from Philadelphia
.sup.(5) from Houston
Source of Circosol, Sunpar, Sundex, Sunthane oils was Sun Oil
Source of Flexon oils was Exxon
Source of Tufflo oils was Arco
The third essential ingredient of the composition of the present invention
is clay. A standard text defines clay as "a disperse system of mineral
fragments of hydrated aluminum silicate of which particles smaller than
two microns predominate." "The term `clay` refers to a physical condition
and not to a definite chemical composition" (Kaolin Clays and Their
Industrial Uses--J. M. Huber Corporation, New York, N.Y., 2nd edition,
1955 p.15). A common way of writing the formula is Al.sub.2
O.sub.3.2SiO.sub.2.2H.sub.2 O. Clays used in rubber are classified as
"hard" and "soft" types. "Clays which produce a high modulus, high tensile
strength, good resistance to abrasion, and a stiff, uncured compound are
called `Hard` clays." (Ibid, p. 15) "Those that produce lower modulus . .
. etc. are called `Soft` clays." "This is an arbitrary classification and
has no connection with geological formation or chemical composition."
The amount of clay in the composition of the present invention should be
from about 5 to about 50% by weight, preferably from about 15 to about 50%
by weight and most preferably from about 15 to about 25% by weight.
Polymers, both homo- and copolymers, other than the ones referred to above,
and filler, other than clay can also be used to some extent in the
composition of the present invention without significantly interfering
with the advantages obtained by the present invention. Similarly other
ingredients can also be added to the compositions of the present invention
by a compounder in order to obtain some desired effect, such as reduction
of cost, or enhancement of physical property. Accordingly, extender
resins, waxes, foaming agents, antioxidants etc. that are widely used,
particularly in hot melts, can be included in the compositions of the
present invention in an amount of up to about 90% by weight, preferably up
to about 75% by weight and most preferably in an amount of from about 10
to about 50% by weight.
A commercially sized batch-type Banbury or equivalent intensive mixer is
entirely suitable for preparing the compositions of the present invention.
A Farrel continuous mixer ("FCM") is also an excellent mixing device. In
either instance, dry ingredients are charged in routine fashion. It is
convenient in most cases to inject the oil component directly into the
mixing chamber of either unit as per widely used practice with this type
of equipment. Oil addition should precede fluxing of the charge. A mix
cycle of about 3 minutes is generally adequate for the Banbury mixer at an
operating temperature usually between 325.degree. and 375.degree. F. The
operating rate for the FCM unit generally will fall within ranges
predicted by literature prepared by the Farrel Company, Ansonia,
Connecticut. Again, temperatures between 325.degree. and 375+ F. are
effective. In both cases, a very low oil level, say about 2-3%, may
require higher temperatures, while oil levels above about 7% may mix well
at lower mixer temperatures. While not evaluated, it is expected that
other devices for handling viscous mixes (MI of 0.1 to 20) should be
entirely satisfactory--but in any case, prototype trials in advance are
desirable.
Once blends are mixed, routine commercial practices may be used, such as
underwater melt cutting plus drying or use of sheeting plus chopping
methods, to produce a final pelletized product.
Primary use for the compositions of the present invention will probably be
in the sheeting field, particularly for low cost, dense, sound-deadening
structures. Outstanding characteristics such as improved "hand", "drape",
reduced stiffness, and reduced thickness of the extruded sheeting result
from the compositions of the present invention.
Low-level filler uses are of course also possible, (see e.g., the
compositions of Table II below). While these blends are very simple hot
melt compositions, they are indicative of blends which can be used for
compounding (after inclusion of tackifiers, fillers, extenders, etc.)
blends for use in: hot melt adhesives applied by wheel applicators or
guns; and coating blends for corrugated shipping containers, or for
coating of paperboard carton stock.
The blends of the present invention can readily be extruded onto a
substrate, such as an automotive carpet, or can be extruded or calendered
as unsupported film or sheet. Depending upon the equipment used, and the
compounding techniques employed, it is possible to extrude wide ranges of
film thickness, from below 20 mils to above 75 mils. While not
demonstrated, a film thickness of even less than 10 mils and over 100 mils
could probably be readily attained. This then provides industry with an
opportunity to vary the amount of sound deadening to be attained by
varying film thickness, density of blends, ratio of filler load to binder,
and similar techniques well known in the art.
In the application of the compositions of the present invention in carpets,
the initial "soft" carpet manufacturing stages--tufting of loops, cutting
them to form a plush if desired, dyeing and drying, and then storing as
unbacked "soft" roll goods until ready to apply a back-coating--are
entirely similar to well-known methods as already described in patents,
e.g.,: Stahl, U.S. Pat. No. 3,645,948. The disclosure of this patent is
hereby incorporated by reference.
The following examples are given for the purpose of illustrating the
present invention. All parts and percentages are by weight unless
otherwise specified.
EXAMPLE 1 AND COMPARATIVE EXAMPLE 1
As indicated above, blends which contain both ethylene/vinyl acetate
copolymer and clay rapidly decompose and liberate copious quantities of
anhydrous acetic acid. A blend that shows such characteristics is
illustrated in Table I. Both blends were premixed for about 1/2 minute
before being charged to the Banbury mixer. Optionally, the Banbury mixer
can be used as the premix vessel, merely by rotating the mixing blades for
15-30 seconds before lowering the ram which closely confines the blend
ingredients in the mix chamber. Blend C-1 decomposed within two minutes in
a standard Banbury mixer blending cycle. It turned gray, emitted copious
quantities of anhydrous acetic acid and was discarded. On the other hand,
the blend of Example 1 was readily milled in a Banbury mixer with no signs
of degradation, no gray color and no emission of acetic acid.
TABLE I
______________________________________
Ingredients (parts by wt.)
Ex. C-1 Ex. 1
______________________________________
EPDM.sup.(1) 6 6
EVA #1.sup.(2) 11 11
"SUPREX" Clay.sup.(3)
5 5
"CIRCOSOL" 4240 -- 8
______________________________________
.sup.(1) terpolymer of ethylene, propylene and a nonconjugated diene.
.sup.(2) 25% vinyl acetate, 75% ethylene, M.I. = 6.
.sup.(3) Georgia hard clay from J.M. Huber Co., (chemically = Al.sub.2
O.sub.3 . 2SiO.sub.2 . 2H.sub.2 O)?
EXAMPLES 2-3 AND COMPARATIVE EXAMPLES 2-3
Four compositions were prepared as shown in Table II. Melt preparation can
be accomplished in any convenient stirred laboratory-type beaker or tank.
The order of addition was as follows.
Blend C-2: (1) wax melted, (2) EVA added, (3) clay added after EVA
dissolved, (4) blended 10 minutes and poured.
Blend C-3: (1) wax melted, (2) clay added, (3) blended 10 minutes, and (4)
EVA added.
Blend Ex. 2: (1) wax melted, (2) "CIRCOSOL" oil added, (3) clay added, (4)
EVA added.
Blend Ex. 3: (1) wax melted, (2) "CIRCOSOL" oil added, (3) oven dried clay
added, (4) EVA added,
Viscosity measurement was done by a Brookfield Thermosel where blend is
maintained at 190.degree. C. and viscosity was measured at appropriate
intervals.
TABLE II
______________________________________
Ingredients Ex. C-2 Ex. C-3 Ex. 2 Ex. 3
______________________________________
EVA #2.sup.(1)
30 30 30 30
Paraffin Wax.sup.(2)
50 50 45 45
"SUPREX"Clay 20 20 20 20
"CIRCOSOL" 4240
-- -- 5 5
Clay:Oil Ratio 4:1 4:1
Thermosel Viscosity
(cp) After Time
Exposure of X Hrs.
AT 190.degree. C.
Initial 2300 1800 1150 1100
1 Hr. 4500 2200 1200 1100
5 Hr. -- 2700 1300 1100
10 Hr. -- 3100 1350 1100
15 Hr. -- 3350 1400 1100
20 Hr. -- -- 1550 1120
30 Hr. -- -- 1800 1200
40 Hr. -- -- -- 1400
50 Hr. -- -- -- 1750
60 Hr. -- -- -- 2300
______________________________________
.sup.(1) 25% vinyl acetate, 75% ethylene, 25 MI.
.sup.(2) "Pacemaker" 53, a fullyrefined paraffin wax, from Cities Service
& Continental Oil Corporation.
In comparing blend C-2 vs C-3, it is evident that both are highly
unstable--but C-3 is less unstable than is C-2, as the result of a
modified compounding procedure. In both cases, the "pot life" under
practical application conditions, is not acceptable.
Example 2 and Example 3 blends are clearly far more stable than are C-2 and
C-3. The stability increase is directly attributable to the passivating
effect of the processing oil present.
The decomposition/stability data of the present examples shows that the
processing oil passivation method is effective with low filler level hot
melt blends also.
Table II shows that the clay:oil ratio for Examples 2 and 3 is 4:1. The
blends of Example 2 and
Example 3 are stable for far longer than are the clay containing, oil-free
blends of Comparative Blends C-2 and C-3. Blends C-2 and C-3 increase in
viscosity so rapidly that they are of little or no value in commercial
systems. By contrast, the Example 2 blend will have a useful "pot life" at
190.degree. C. of perhaps 20 to 30 hours; while blend Example 3, based on
clay which has been oven dried for 24 hours at 120.degree. C. prior to
compounding, will have a "pot life" approaching 50 hours.
EXAMPLES 4-7 AND COMPARATIVE EXAMPLE 4
The ingredients were premixed in a one-gallon (about 3.8 liter) can by
shaking manually for about one half minute. The charge was then added to
Banbury type laboratory size intensive high shear mixer. Mix conditions
employed were fluxing for three minutes at the temperature of
325.degree.-375.degree. F. (about 160.degree.-190.degree. C.). Composition
and physical properties of the blends are summarized in Table III.
A processing oil is a key ingredient required for passivation of clay in
simple blends based on EVA, clay, and inert fillers. The capacity of a
given amount of oil in passivation of clay is limited. This is shown by
examination of Table III, where a 3:1 clay:oil blend can be mixed without
difficulty, but a 4:1 blend show signs of EVA decomposition.
Comparative Example 4 of Table III has no clay but does have 72.5% of an
inert filler--#9 whiting. The blend can readily be made in a commercial
intensive mixer, by batch means, such as a Banbury Mixer, or by continuous
means, such as a Farrel Continuous Mixer. Other intensive mixers should be
equally effective. There were no signs of blend degradation noted, such as
darkening, or emission of acetic acid (HAc) vapor formed on decomposition
of EVA resin.
Examples 4 through 7 show what happens as a portion of the Whiting is
replaced, weight for weight, by "Suprex" clay. Blends of Examples, 4, 5,
and 6 are stable and process well. No acid odor develops. Blend 7 is no
longer stable; within a 3-minute Banbury cycle at about 350.degree. F.,
the relatively high amount of clay (4 times the oil weight) has caused the
EVA resin to degrade, as evidenced by the pungent acetic acid odor which
results when EVA resins decompose. Thus, for this specific system, the
limit of clay addition is between 3 and 4 times the amount of oil added.
TABLE III
______________________________________
Ingredients Ex. C-4 Ex. 4 Ex. 5
Ex. 6
Ex. 7
______________________________________
EVA #1 16 16 16 16 16
EVA #3.sup.(1)
4.2 4.2 4.2 4.2 4.2
"CIRCOSOL" 4240
7.3 7.3 7.3 7.3 7.3
#9 Whiting.sup.(2)
72.5 65.2 57.9 50.6 43.3
"SUPREX" Clay
-- 7.3 14.6 21.9 29.2
SP.GR. Of Blend
1.79 1.78 1.78
1.82
No
Tensile
Strength,.sup.(3) PSI
606 631 630 673 TESTS
kPa 4180 4350 4350 4640 MADE-
Elongation, .sup.(3) %
34 36 48 46 BLEND
Thickness of NOT
Strip, Mils 59 59 59 59 STABLE
mm 1.50 1.50 1.50
1.50
(ACETIC
Stiffness of ACID
Strip,.sup.(4) g
66 63 65 84 ODOR)
Clay:oil Ratio
-- 1:1 2:1 3:1 4:1
______________________________________
.sup.(1) 7.5% VAc; 92.5% ethylene; 1.2 M.I.
.sup.(2) CaCO.sub.3, as commercial ground limestone; from Georgia Marble
Co.
.sup.(3) Tensile strength & elongation measurements were made using ASTM
Method D 1708 at crosshead speed of 2 in (5.1 cm)/min. Samples were 0.876
in. (2.23 cm) .times. 0.187 in. (0.47 cm) in size, at strip thickness
shown in table. (Instron Tester used.)
.sup.(4) Stiffness of strip was measured by placing a 1" .times. 6" (2.54
cm .times. 15.2 cm) strip on a platform balance, and measuring the force
required to make the ends of the test strip meet, at room temperature.
Table III also shows the change in properties which occurs in a blend that
contains a fixed percentage of EVA, oil, and filler, at 72.5% filler load,
as the filler is changed from all Whiting (C-4) to a substantial
substitution of clay for Whiting (Ex. 6). The tensile strength has
increased by about 10%, while the elongation has increased by about 35%.
However, the blend has also become substantially stiffer--by almost 30%.
This effect may or may not be desirable, depending upon the contemplated
end use.
EXAMPLES 8-11
The blends were prepared according to the method of the preceding examples.
Compositions and physical properties are summarized on Table IV. The data
shows that oils other than "CIRCOSOL" 4240 are also highly effective in
preventing EVA decomposition resulting from contact during mixing with
clay at elevated temperatures. Thus, paraffinic and aromatic oils are as
effective as "CIRCOSOL" 4240, which is naphthenic oil.
Table IV further shows that the choice of the type of oil and its viscosity
is also influential and must be considered by the compounder. Changing the
oil type and the oil viscosity will influence key properties such as
tensile strength, elongation, and stiffness--all of which are important to
the compounder. None of these changes are "good" or "bad" on an arbitrary
basis; the skilled compounder knows that the proper balance of properties
is the key to matching end-use demands and thus will employ clay/oil
systems when advantages result. This includes deciding whether the
ultimate surface characteristic should be "dry"--or slightly oily. For
most end uses, a dry feel is required. However, for certain uses, such as
mold or form release coatings, a slightly oily surface could prove highly
advantageous. As the data show, "dry" surfaces are best secured by
inclusion of aromatic or naphthenic oils, while paraffinic oils have a
definite tendency towards "bleeding".
TABLE IV
______________________________________
Ingredients Ex. 8 Ex. 9 Ex. 10 Ex. 11
______________________________________
EVA #1 16 16 16 16
EVA #3 4.2 4.2 4.2 4.2
"CIRCOSOL" 4240
#9 Whiting 50.6 50.6 50.6 50.6
"SUPREX" Clay
21.9 21.9 21.9 21.9
"FLEXON 391" 7.3 -- -- --
"FLEXON 865" -- 7.3 -- --
"SUNDEX 8600T"
-- -- 7.3 --
"SUNPAR 2280"
-- -- -- 7.3
SP.GR. of Blend
1.81 1.79 1.81 1.77
Tensile
Strength, PSI
693 516 785 519
kPa 4780 3560 5410 3580
Elongation, %
38 46 42 36
Stiffness, g 84 97 91 86
Thickness of
Strip, Mils 59 59 59 59
mm 1.50 1.50 1.50 1.50
Does Oil
Exude? NO YES- NO YES-
1 Day 1 Day
Banbury HAc
Odor? NO NO NO NO
______________________________________
EXAMPLES 12-19 AND COMPARATIVE EXAMPLES 5-10
These examples provide further illustration of the composition of the
present invention with different types of EVA copolymer and with varying
levels of clay, oil and filler compared to filler compositions without
clay. Compositions, and physical properties are summarized in Table V. In
spite of the difficulty in precisely measuring physical properties of thin
strips, of thermoplastic blends the overall conclusion remains; i.e.,
inclusion of clay in blends is useful to the compounder who seeks
additional stiffness and higher elongation in such blends. This
combination might be of particular value when blends are to be used to
produce molded articles. Table V also shows that compounding is possible
over a wide variation in type of EVA and over a broad range of filler
levels. Finally, Example 19 shows once again the need to maintain enough
oil to passivate the clay. In this case, the 5:1 clay:oil ratio proved to
be too high.
TABLE V
__________________________________________________________________________
Ex.
Ex.
Ex.
Ex.
Ex.
Ex.
Ex.
Ex.
Ex.
Ex.
Ex.
Ex.
Ex.
Ex.
Ingredients
C-5
12 C-6
13 C-7
14 C-8
15 C-9
16 C-10
17 18 19
__________________________________________________________________________
EVA #4.sup.(1)
-- -- -- -- -- -- -- -- -- -- -- -- -- 18
EVA #2 15 15 10 10 9 9 11.25
11.25
10.5
10.5
8.0
8.0
-- --
EVA #1 15 15 10 10 9 9 11.25
11.25
10.5
10.5
8.0
8.0
-- --
EVA #5 .sup.(2)
-- -- -- -- -- -- -- -- -- -- -- -- 21 --
"CIRCOSOL" 4240
5 5 5 5 7 7 7.5
7.5
9.0
9.0
9.0
9.0
9 7
#9 Whiting
65 60 75 70 75 68 70 62.5
70 65 75 66 60 40
"SUPREX"Clay
-- 5 -- 5 -- 7 -- 7.5
-- 5 -- 9 10 35
SP.GR. of Blend
1.64
1.65
1.87
1.87
1.87
1.85
1.76
1.76
1.76
1.73
1.85
1.87
1.74
1.84
Tensile
Strength, PSI
458
542
685
695
585
579
557
534
488
500
482
479
490
568
kPa 3160
3740
4720
4790
4030
3990
3840
3680
3360
3450
3320
3300
3380
3920
Elongation, %
326
418
18 23 19 27 37 56 38 50 23 25 51 12
Thickness of
strip, Mils
68 67 58 58 59 58 62 62 62 62 58 57 62 59
mm 1.73
1.70
1.47
1.47
1.50
1.47
1.57
1.57
1.57
1.57
1.47
1.45
1.57
1.50
Stiffness of
strip, g 79 81 84 94 73 75 65 67 62 60 53 60 98 132
Odor noted.sup.(3)
No No No No No No No No No No No No No Yes
__________________________________________________________________________
.sup.(1) 18% VAc; 82% ethylene; M.I. = 2.5
.sup.(2) 28% Vinyl Acetate; 72% ethylene; M.I. = 6.0
.sup.(3) Odor of acetic acid, indicative of decomposition of EVA Resin.
EXAMPLES 20-23
Most of the earlier examples (except for Ex. 7 & 19) had a clay content of
about 20% or below. The effects noted earlier apply with equal force at
higher levels as illustrated in Table VI. Here, the first pair of
blends--Examples 20 and 21--show the same effect for both of th | | |
