Note: Descriptions are shown in the official language in which they were submitted.
1~2;~3~"7
BACKGROUND OF THE INVENTION
Field of the Invention
.
This invention relates to polymeric compositions use-
ful in coating applications. More specifically, this invention
relates to polymer compositions having good melt flow under zero
shear conditions ahd useful in coating various substrates such
,.
as glass bottles which are employed as containers particularly
in the carbonated beverage and beer industries.
Description of the Prior Art
The hazards of using glass containers, particularly
glass bottles which contain beer or carbonated beverages, are
well known. Breakage of such bottles often takes place due to
the internal pressure exerted by the pressurized gas in the
carbonated beverage or beer as well as by dropping the bottles
and other impacts caused by external forces which occur not
only in the course of production and distribution of the bottled
product, but also as a result of handling of the bottled product
by consumers. Such breakage may result in injuries to the
human body. -
Coatings have been applied to such bottles in order to
prevent scattering of the broken glass upon breakage. In this
connection, see West German Patent PT 2,636,157 and U.S. Patent
3,823,032. The latter patent discloses that thermoplastic elas- '
tomers such as block copolymers of styrene and butadiene are 'i
useful in coating glass bottles. Thermoplastic elastomeric ~i
compositions, having improved environmental resistance, are 3
disclosed in U.S. Patent 3,686,365.
Because of the rather recent concern with environmental
considerations, it is especially desirable to be able to apply
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1122,3~7
proteetive eoatings to various substrates sueh as glass bottles
- in a non-polluting manner. The use of solid powder particles
to eoat these substrates eliminates the need for solvent and
the aeeompanying environmental problems. In this eonnection,
see U.S. Patent 3,737,401.
When the powder particles are deposited upon a substrate
sueh as a glass bottle, the particles must be heated to provide
a uniform molten coating on the glass bottle. The coating is then
eooled to provide a uniform solid eoating on the bottle.
When certain thermoplastic elastomers such as styrene/-
butadiene/styrene bloek copolymers are used as a major component
of the powder particles, the melt flow of the thermoplastic
elastomers is not suffieient to provide a uniform molten eoating.
Although it is known to use copolymers of alphamethylstyrene and
styrene with eertain elastomers to produee pressure sensitive
adhesives and to use sueh additives in hot melt coatings (see
U.S. Patent 3,932,332), the use of this additive does not provide
suffieient flow in thermoplastie elastomers at temperatures below
that at whieh the thermoplastie elastomer discolors.
It is also known to use hydrogenated aromatic hydro-
earbon petroleum resins as tackifiers for polymers sueh as styrene/-
isoprene/styrene block copolymers in a hot melt adhesive. For
example, United States Defensive Publieation T917008 diseloses
a hot melt adhesive eontaining a taekifier whieh is derived from
a polymerized eraeked naphtha fraetion and having a boiling point
between -10 and 280C. This fraction contains polymerizable
unsaturated hydrocarbons, inert paraffins and alkyl benzenes.
In some instances thermoplastic elastomer powder
partieles tend to eoalesee and become tacky, lumpy materials
whieh are diffieult to spray. Such powders tend to produce
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11223~7
eoatings which have the appearance of an orange peel. This
tendency of thermoplastic elastomers to stick together, coalesce,
agglomerate and/or exhibit "blocking"; results from an undesired
adhesion between touching particles such as occurs under moderate
pressure during storage of the particles. Particularly, storage
under somewhat elevated temperatures, and under pressures caused
by stacking bales or packages of polymer, create conditions
favorable for such agglomeration. If the particles of the
polymers agglomerate, then it frequently becomes necessary to
grind, crush, or otherwise masticate the mass in order to resep-
arate the particles or to again produce a utilizable particulate
material. Such mechanical treatment is burdensome and undesirable
beeause of inconvenience, added labor and time, cost, possible
eontamination of the elastomer, and possibly in some instances
even degradation of some of the polymeric products due to the
additional working, temperature and the like.
In attempting to ease this problem, it is known to apply
a dusting agent such as carbon black, talc, zinc stearate, rice
flour, ehalk, magnesium oxide, infusorial earth, or the like, to
the partieles in an effort to counteract the natural tackiness
- or bloekiness of the partieulate-form polymers. All of these
dusting agents, however, have some objectionable characteristics.
For example, adding color to the natural polymer may be undesir- 1-
able for some purposes. The dusting agents may be objectionable
for some end uses, such as in clear eoatings where the presence
of sueh agents eould cause haziness. Silica powder and some
grades of talc may possible pose health hazards under some circum-
stances that will restrict their use. Stearate powders at levels
sufficient to combat tackiness may adversely affect polymer
performance properties such as tack, adhesion, optical clarity,
and the like. For a more detailed discussion of the disadvantages
of p-ior art attempts to solve this general problem, see U.S.
_ 4 - ~,
. . .
-
.. . .
lZZ,3~7
Patents 3,528,841 and 4,027,067 and British Specification
1,200,532.
; SVMMARY OF THE INVENTION
In one aspect, the present invention provides a powder
composition useful for coating applications comprising a melt
blend mixture of
a) a block copolymer which is selectively hydrogenated
to at least some degree and having at least two kinds of polymer
blocks wherein one polymer block is designated by A and a second
polymer block is designated by B such that prior to hydrogenation,
l) each A is a polymer end block of a
; monovinyl or alpha alkyl monovinyl arene
having a number average molecular weight
in the rar.ge of from 5,000 to 75,000, the
blocks A comprising from 5 to 50% by weight
of total block copolymer, and
2) each s is a polymer mid block having a
number average molecular weight of from
30,000 to 300,000, and formed from a con-
jugated diene selected from homopolymers
of at least one conjugated diene having 4
to lO carbon atoms per molecule, the blocks
B comprising from 50 to 95% by weight of
the total block copolymer, and
25 , b) at least one melt flow modifier selected from the
: ` group consisting of
l) monovinyl arene homopolymers
. 2) alpha alkyl monovinyl arene homopolymers,
and
3) copolymers of monovinyl arenes and alpha-
.' ,. I
- !
: - 5 -
, ~
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,1 1.
~1~2347
alkyl monovinyl arenes
wherein the aromatic portions of the polymer described
in b) 1), 2) and 3) are at least partially hydrogenated
to remove the aromatic character thereof,
wherein the powder composition possesses good melt flow charac-
teristics under zero shear conditions.
In another aspect, the present invention provides a
process for preparing this powder composition. This process
comprises
A) melt blending a mixture of the block copolymer
described as (a) hereinbefore with the melt flow modifier described
as (b) hereinbefore to produce a molten mixture;
B) cooling the mixture to form a solid composition,
C) pelletizing the solid composition, and
D) grinding the pellets to desired particle size.
In still another aspect, the present invention provides
a non-tacky powder composition useful for coating applications.
This powder composition comprises tacky powder particles and,
adhering to the tacky surface of these tacky particles in a non-
-continuous layer, smaller solid particles which are hard and
non-tacky.
The tacky powder particles comprise a melt blend mixture
of
(1) a block copolymer and
(2) at least one melt flow modifier as described
hereinbefore.
The smaller solid particles are hard and non-tacky and comprise
at least one melt flow modifier described above with the provision
that such a melt flow modifier have a glass transition temperature
of at least about 20~C.
~,
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1~223~-7
In yet another aspect, the present invention provides
a process for preparing the non-tacky powder composition. This
process c~mprises t'
(A) melt blending a first composition comprising
(1~ the block copolymer, and
(2). at least one of the melt
flow modifiers,
(B) cooling the first molten composition to form a
solid composition,
(C) pelletizing the solid composition,
(D) dry blending the pelletized composition with the
hard, non-tacky solid and
(E) eomminuting the dry blend at a temperature below
the embrittlement temperature of the B block portion of the
thermoplastie elastomer to form hard, non-tacky powder particles.
In still another aspect, the present invention provides
a proeess for coating a glass eontainer and the coated glass con-
tainer obtained by the proeess. This proeess eomprises
A. preheating a glass eontainer,
B. applying on the external wall surfaee
of the eontainer the powder eomposition
deseribed above,
C. baking the eoated eontainer until the
powder partieles beeome molten and form a
smooth, molten coating on the glass surfaee,
D. applying to the eoated eontainer a
synthetie resin selected from the group
eonsisting of epoxy resins, polyurethanes,
polyearbonates, polyesters, polystyrenes,
ethylene/vinyl aeetate eopolymers and
aerylie homopolymers and eopolymers
wherein the synthetie resin is applied to
substantially the entire surfaee of the first
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coating and also to a part of the glass bottle surface,
E. baking the coated container until the synthetic
resin forms a smooth coating, and
F. cooling the coated bottle to substantially ambient
temperature.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Thermoplastic elastomers are polymeric materials that
behave in some ways like thermoplastics and in other ways like
elastomers. They behave like thermoplastics in that above their
softening point they may be processed using ordinary plastics
processing equipment. For example, they may be formed by thermo-
plastic injection molding, extrusion, blow molding, or vacuum
forming. On the other hand, when utilized below their softening
point, they behave like elastomers, i.e., they exhibit the prop-
erties normally associated with vulcanized rubbers without
having been subjected to vulcanization. Thus, such polymers
have the elastic and resilient properties of rubber but may be
processed and reprocessed like ordinary thermoplastics.
; The thermoplastic copolymers useful in the present
invention are block copolymers having at least two kinds of
polymer blocks. Copolymers useful in the present invention are
described in "Applied Polymer Science", Chapter 29, p. 394ff,
of Organic Coatings and Plastics Chemistry (Craver ~ Tess, 1975).
Preferred block copolymers for use in the present inven-
tion are radial or branched block copolymers. By "radial" or
"branched" copolymers is meant copolymers having the general
configuration
Z (BA)n
wherein each A group is a terminal block segment comprising a
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;23~7
polymer made from a monovinyl or alpha alkyl monovinyl arene
and each B is a block segment comprising a polymer made from a
conjugated diene, Z is derived from a polyfunctional compound
having at least three reactive sites, and n is not less than 3.
The radical block copolymer, as herein defined, must have at
least three block copolymer branches radiating from a nucleus Z.
The "Z" group which forms the nucleus from which the
polymer blocks of the radical block copolymer radiate is derived
from a polyfunctional compound having at least three reactive
sites capable of reacting with a carbon-lithium bond. Types
of polyfunctional compounds which can be used include the poly-
epoxides, polyisocyanates, polyimines, polyaldehydes, polyketones,
polyanhydrides, polyesters, polyhalides and the like. A pre-
ferred polyfunctional compound is a silica containing compound.
The preparation of the preferred radial block copolymers
of this invention may be by any technique known to those skilled
in this art, such as those described in United States Patents
3,932,327; 3,692,874 and 3,281,383.
These radial block copolymers are available commercially
as Solprene thermoplastic elastomers.
An important subgroup of these block copolymers com-
prises those thermoplastic elastomers in which the olefinic
double bonds in the diene polymer blocks are converted to
saturated hydrocarbon units by selective hydrogenation of the
preformed block copolymer. The object of the hydrogenation is
` to improve the environmental resistance of the olefinically
unsaturated block copolymer, particularly its resistance to
light, oxygen, ozone, and heat. The thermoplastic elastomeric
block copolymers useful in the present invention are at least
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1~22347
partially selectively hydrogenated as described in United States
Patent 3,810,957.
The thermoplastic elastomers useful in the present
invention comprise generally from 5 to 50, and preferably from
15 to 35% by weight monovinyl or alpha alkyl monovinyl arenes
and generally from 50 to 95, and preferably from 65 to 85% by
weight conjugated diene which is either substantially unhydrogen-
ated or at least partially hydrogenated.
The monovinyl arene or alpha alkyl monovinyl arene
useful as the aromatic block of the thermoplastic elastomer
; includes styrenes, alpha alkyl styrenes, ring alkylated styrenes,
such as vinyl toluene and t-butyl styrene, alpha, alpha dialkyl
styrenes, ring halogenated styrenes such as the chlorostyrenes,
` vinyl naphthalenes and the like or mixtures thereof. Styrene
and alpha methyl styrene are preferred.
The conjugated dienes useful in preparing the thermo-
, plastic elastomer include butadiene, alkyl substituted butadienes
-. such as isoprene,2,3-dimethyl butadiene, ethyl butadiene, methyl
pentadiene, ~piperylene) and the like, or mixtures thereof. The
alpha, gamma conjugated butadienes are preferred. Unsubstituted
alpha, gamma butadiene is particularly preferred.
A typical, but by no means exhaustive, list of suitable
block polymers includes the following:
Polystyrene-polybutadiene-polystyrene,
Polystyrene-polyisoprene-polystyrene,
Polystyrene-poly(random butadiene-styrene)-
polystyrene,
Poly(alpha-methylstyrene)-polybutadiene-poly-
(alpha-methylstyrene),
Poly(alpha-methylstyrene)-polyisoprene-poly-
(alpha-methylstyrene), and
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Poly(styrene-alpha-methylstyrene)-poly-
(butadiene-isoprene) (styrene-alpha-
-methylstyrene).
~he number avera~e molecular weight of the thermoplastic
elastomers useful in the present invention may be generally from
15,000 to 150, 000! and preferably from 50,000 to 80,000.
The conjugated diene portion of the thermoplastic
elastomer may be hydrogenated to any degree lncluding substan-
tially complete saturation whereas the aromatic portion is left
substantially unhydrogenated, e.g., less than 5%, preferably less
than 2% hydrogenated. The conjugated diene portions of the ther-
moplastic elastomers useful in the present invention are hydro-
genated to generally at least 10%, typically at least 50%, and
preferably at least 98%. Substantially complete hydrogenation
of the conjugated diene portion is preferred.
Thermoplastic elastomers which are at least partially
hydrogenated are preferred for use in the present invention
since these polymers have improved ultra violet light exposure
stability, improved outdoor weatherability, and improved thermal
stability. Also, unexpectedly, those polymers which are at
least partially hydrogenated do not "blush" or absorb water when
in contact with a caustic solution to the same extent as do those
polymers which are not at least partially hydrogenated. By
"blush" is meant that the coating acquires some degree of opaqueness
when in contact with an aqueous solution. ~
, The melt flow modifier useful in the present invention
may be selected from the group consisting of monovinyl arene
homopolymers, alpha alkyl monovinyl arene homopolymers, and
copolymers of monovinyl arenes and alpha alkyl monovinyl arenes
either with each other or with other comonomers. These modifiers
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2347
must be at least partially hydrogenated. Copolymers of monovinyl
arenes and alpha alkyl monovinyl arenes either with each other or
with other comonomers are preferred. Copolymers of these com-
pounds with each other are particularly preferred. Copolymers of
monovinyl arenes and alpha alkyl monovinyl arenes which are not
hydrogenated are described in United States Patent 3,932,332.
The monovinyl arenes useful in preparing the melt flow
modifier include styrene, ring alkylated styrenes such as vinyl
toluene and t-butyl styrene, vinyl naphthalenes, ring halogenated
styrenes such as the chlorostyrenes, and the like and mixtures
thereof. Styrene is a preferred monovinyl arene.
The alpha alkyl monovinyl arenes useful in preparing
the melt flow modifier include alpha methyl styrene, ring
alkylated alpha methyl styrenes, alpha, alpha dialkyl styrenes
and the like and mixtures thereof. Alpha methyl styrene is a
preferred alpha alkyl monovinyl arene.
When a copolymer comprising substantially only monovinyl
arenes and alpha alkyl monovinyl arenes is used as the melt flow
modifier, the copolymer contains generally from 10 to 50, and
preferably from 20 to 30% by weight monovinyl arene, and generally
from 50 to 90, and preferably from 70 to 80% by weight alpha alkyl
monovinyl arene. A particularly preferred copolymer is a copolymer
of styrene and alpha methyl styrene.
Many compounds could not be used as melt flow modifiers
in combination with the thermoplastic elastomer because such
compositions would not have satisfactory melt flow. For example,
compositions which have a melt index less than about 2.0 grams
per ten minutes at 200C do not have satisfactory melt flow.
(For details of the melt index test, see ASTM D-1238.) Even some
''' 1~2234q
of those compositions which have a melt index greater than about
2.0 grams per 10 minutes at 200C. are not useful in the present
invention since in the melt index test; there is a force which
pushes the material through an orifice whereas when powders are
melted on a substrate, no force is applied to the molten powder
particles. Thus, the compounds, useful as melt flow modifiers
in the present invention must result in a final composition having
sufficient melt flow under zero shear conditions.
Some compounds will form a mixture with the thermoplastic
elastomer which has a melt index greater than 2.0 but are not
compatible with the thermoplastic elastomer and thus result in 3
opaque compositions. Others are compatible but do not provide
enough plasticization to the phases to allow them to flow under
zero shear. Finally, some compounds which are otherwise accept-
able as melt flow modifiers are not useful in compositions used
to coat glass bottles because they do not provide compositons ,
., . ~
which possess sufficient fragment retention.
Unlike the copolymers described in U.S. Patent
3,932~332, the polymers useful as the melt flow modifiers in the
present invention must be at least partially hydrogenated, i.e.,
at least part of the arene nuclei must be saturated. If the arene
nucleus is benzene, the hydrogenated product would thus be cyclo-
hexane. The melt flow modifiers of the present invention are
generally at least 20, and preferably from 30 to 90~ hydrogenated.
Preferred melt flow modifiers for use in the present ~j
invention include a copolymer comprising 25% styrene and 75%
alpha methyl styrene which is about 35% hydrogenated, has a
softening point range between 42 and 62C., has a number average
molecular weight of 738, a weight average molecular weight of
1230, and a molecular weight distribution of 1.7. Another such
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11;22347
polymer is a copolymer comprising 25% styrene and 75% alpha
methyl styrene which is about 65% hydrogenated, has a softening
point range between 45 and 65C., has a number average molecular
weight of 725, a weight average molecular weight of 1120, and a
molecular weight distribution of 1.5.
By sol-ubility parameter is meant the square root of the
cohesive energy density. Eor a detailed discussion of this
term, see "Polymer Handbook" Section IV, pp. 341-68 by Brandrup, J
& Immergut, E. H. (Interscience Division of John Wiley & Sons, N.Y.,
N.Y., 1966). The melt flow modifiers useful in the present
invention may be chosen on the basis of their solubility parameters,
The preferred melt flow modifier for a particular thermoplastic
elastomer should have a solubility parameter between the solu-
bility parameter of the aromatic portion and the conjugated diene
or saturated diene portion of the thermoplastic elastomer. For
example, a particularly preferred thermoplastic elastomer com-
prises 80% by weight substantially totally hydrogenated butadiene
(having a solubility parameter of about 8) and 20~ by weight
styrene (having a solubility parameter of about 9). When this
particularly preferred thermoplastic elastomer is employed, the
melt flow modifier should have a solubility parameter of generally
from 6 to ll,and preferably from 8 to 9.
In the present invention there is employed generally
from 25 to 90, and preferably from 50 to 70% by weight thermo-
plastic elastomer and generally from 10 to 75, and preferablyfrom 30 to 50% by weight melt flow modifier.
The melt flow modifier useful in the present invention
must contain aromatic portions which are at least partially
hydrogenated in orde~ that the melt flow modifier will be com-
patible with both the aromatlc and aliphatic portions of the
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thermoplastic elastomers. The aromatic portion of the melt
flow modifier is compatible with the aromatic portion of the
thermoplastic elastomer and the hydrogenated or saturated
portion of the melt flow modifier is compatible with the ali-
phatic portion of the thermoplastic elastomer.
In a preferred embodiment of the present invention,
other materials known to those skilled in this art may be added
to the composition of the present invention. These materials
include adhesion promoters and stabilizers.
The adhesion promoters useful in the present invention
are preferably silanes but, in the broadest aspect of the present
invention, adhesion promoters such as titanates, isocyanates,
epoxies, phenoxies, or others known to those skilled in the art
may be employed. The preferred adhesion promoters are substituted
silanes or their corresponding silanols (i.e., the partially or
fully hydrolyzed derivative of the silane) or the corresponding
siloxanes (the polymeric form of the silanol) or mixtures of the
silane, silanol and siloxane. The silane has the general formula:
R2
Y - Rl - ~i - X
R3
wherein Y is selected from the group consisting of mercapto,
epoxy, amino, polymeric amino, methacryloxy, n-alkyls, aryls,
halogenated derivatives of the foregoing and mixtures thereof:
Rl is selected from the group consisting of alkylene, isoalkylene,
and cycloalkylene, each of 2 to 16 carbon atoms; X is selected
from the group consisting of a halogen, hydroxyl, alkoxy, and
acyloxy group; R2 and R3 are selected independently from the
group consisting of Y - Rl - ,X -, and methyl. The Rl group
may also contain more than one substituent group so long as no
23~7
single carbon atom holds more than one such group. Condensation
products of the substituted alkyl silanes are also applicable.
Illustrative of suitable silanes within this structural
formula are: gamma-glycidoxypropyl trimethoxysilane, beta-
(3,4-epoxycyclohexyl)ethyl trimethoxysilane, beta-glycidoxyethyl
triethoxysilane, beta-(3,4-epoxy-cyclohexyl) ethyl tri (beta-
methoxyethoxy) silane, beta-(3-epoxyethylphenyl) ethyl trimethoxy-
silane, gamma-glycidoxypropyl dimethyl methoxy-silane, beta-(epoxy-
ethyl) ethyl triethoxysilane, 4,5-epoxy-n-hexyl trimethoxysilane,
' 10 7,8-epoxy-n-octyl tripropoxysilane, 15,16-epoxy-n-hexadecyl
trimethoxysilane, 3-methylene-7-methyl-6,7-epoxyoctyl trimethoxy-
silane, and their corresponding silanols and siloxanes; t.he mercapto
alkyl silanes such as betamercaptoethyl trimethoxysilane, beta-
-mercaptopropyl trimethoxysilane, betà-(2-mercaptocyclohexyl) ethyl
r~ .
trimethoxysilane, beta-mercaptoethyl triethoxysilane, gamma-mer-
captopropyl dimethyl methoxy-silane, beta-mercaptoethyl triace-
toxysilane, and their corresponding silanols and siloxanes.
The adhesion promoters may generally be added to the
melt in liquid form, i.e., in 100% concentration or as a dispersion
in water, in C4-C16 hydrocarbon solvents such as pentane, hexane,
heptane, benzene, toluene, xylene, etc.-, or in other organic
solvents such as C2-C6 alkanols (e.g., isopropyl alcohol, sec.-
butyl alcohol, etc.) C3-C8 ketones (e.g., acetone, methylethyl
ketone, etc.) and chlorinated alkanes such as carbon tetra-
chloride, chloroform and ethylene dichloride. For the purpose
of convenience herein and in the appended claims, the term "silane"
will be understood to include the unhydrolyzed form (i.e., the
silane), the partially or fully hydrolyzed form (i.e., the silanol),
the condensation products resulting from the partially or fully
hydrolyzed form of the silane (i.e., the siloxane, also known as
2,347
polysiloxane), and mixtures of the aforesaid forms. A particularly
preferred adhesion promoter is gamma-glycidoxypropyl-trimethoxy
silane.
The total amount of adhesion promoter may be incorpo-
rated within the tacky powder particles. However, in the non-
-tacky aspects of this invention, some of the total amount of
adhesion promoter is preferably incorporated within the small
hard non-tacky particles which are surface deposited on the tacky
particles. Thus, in such an embodiment, part of the adhesion
promoter may be incorporated in the tacky powder particles and
part in the small, hard non-tacky powder particles. Alternatively,
the non-tacky powder composition may be slurried in a dispersion
of an adhesion promoter such as a silane in a suitable volatile
solvent followed by evaporation of the solvent. The non-tacky
powder composition is then coated with the adhesion promoter.
Finally, if the final powder composition is to be
applied to a glass container, part or all of the adhesion promoter
may be applied as a primer coat directly to the glass container
itself.
The incorporation of at least part of the adhesion
promoter in the tacky powder particles is preferred. Particularly
preferred is the incorporation of part of the adhesion promoter
in the tacky powder particles and the remainder of the adhesion
promoter is incorporated with the small, hard non-tacky particles.
The amount of adhesion promoter useful in the present
-- .
invention is generally from 0.1 to 10% by weight of the entire
powder composition. When the preferred silane adhesion promoters
are employed, the amount of silane is generally from 0.1 to 8,
and preferably from 2 to 5~ by weight based upon the weight of
the total composition.
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2347
The upper limit of this amount is determined by econo-
mic considerations and also by the fact that too large an amount
of adhesion promoter might be incompatible with the rest of the
powder composition and result in some degree of haziness.
!~ 5 Stabilizers may also be used in the composition of the
present invention especially if the coated article is to have a
long life. For example, a stabilizer against oxidation during
heating and aging and stabilizers against weathering (.V.V. stabili-
zers) may be added in amounts ~f generally less than 10, and
preferably from 1 to 3% by weight of the entire powder composition
Such stabilizers are known.to those skilled in the art
and include 2,4-dihydroxy-benzophenone, substituted hydroxyphenyl
benzotriazole, substituted benzotriazole, 2-hydroxy-4-~2-hydroxy-
-3-methacrylyloxy) propiobenzophenone, octylphenyl salicylate,
resorcinol monobenzoate, 1,3,5-trimethyl-2,4,6-tris (3,5-ditert-
-butyl-4-hydroxybenzyl) benzene, octadecyl 3-(3,5-ditert-butyl-
-4-hydroxyphenyl) propionate, tetra-bis methylene 3-~3,5-ditert-
-butyl-4 hydroxyphenyl)-propionate methane, 2~4-hydroxy-3,5-
-tertiary butyl anilino)4,6-bis(n-octyl thio) 1,3,5~triazine,
.zinc dibutyldithiocarbamate, 2,2-methylene-bis ~4-methyl-6-tertiary
butyl phenol), 2,2'-methylene bis(4,ethyl-6~tert-butyl phenol),
4,4-thiobis(6-tertiary-butyl m-cresol), tri (nonylated phenyl)
phosphite, nickel dibutyl dithiocarbamate, and dibutyl thiourea.
Mixtures of two or more of these stabilizers can also
25 be used.
. The non-tacky powder composition of the present inven-
tion can be prepared by first melt blending a first composition
compris`ing the thermoplastic elastomer and melt flow modifier.
This melt blending step can take place in any apparatus known
to those skilled in this art, such as a plastograph or a twin
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llZ2~47
screw melt extruder.
This melt blending step must be carried out at a
temperatu~e which is high enough to provide sufficient flow
while the composition is molten but low enough so that the
composition does not discolor. Such temperatures are generally
from 100 to 250, and preferably from 130 to 160C.
The molten composition must next be cooled until it
solidifies. Cooling may be done in air or by passing the molten
material through a water bath. When a silane is used as an
adhesion promoter in the present invention, the molten composition
is preferably air cooled. Water contact with the silane should
be kept to a minimum since water appears to affect the adhesion
properties of the silane. ;!
The solid composition is then pelletized and the
pellets are ground to desired particle size.
The particles can be ground by using any apparatus
known to those skilled in this art. Such apparatus include the
Micropul pulverizer, an Abbe mill, a Wiley mill and pin mills.
- The powder particles prepared according to this process
are tacky and tend to agglomerate thus making spraying difficult.
To solve the tackiness problem, the powder particles can be dry
blended with at least one of the melt flow modifiers described
hereinabove with the provision that this melt flow modifier must
itself be non-tacky, i.e., it must have a glass transition
temperature of generally at least 20, and preferably at least
40C.
The term "glass transition temperature" as used in this
application means the temperature at which the melt flow modifier
changes from a brittle, vitreous state to a plastic state.
When the tacky powder particles are dry blended with
-
2347
the non-tacky particles, the non-tacky particles adhere to the
surface of the tacky particles in a non-continuous layer to
form composite powder particles which do not agglomerate.
The powder composition of the present invention com-
prises generally from 3 to 20, and preferably from 8 to 12~ of
the small, hard, non-tacky particles comprising the adhesion
promoter, and generally from 80 to 97, and preferably from 88 to
92% by weight of the tacky powder particles.
The non-tacky particles comprising the adhesion pro-
moter having a glass transition temperature greater than about
20C. can additionally contain incorporated therein part of the
adhesion promoter as described herein~bove. Thus, the non-tacky
powder particles comprise generally from 90 to 100, and preferably
from 95 to 97% by weight melt flow modifier and generally from
0 to 10, and preferably from 3 to 5% by weight adhesion promoter.
As noted hereinabove, part of the adhesion promoter
may be added as a primer coat directly to the surface to be coated
rather than including it within the powder particles. Alterna-
; tively, instead of incorporating all of the adhesion promoter
wlthin the particular or applying part of the adhesion promoter as
a primer coat, part of the adhesion promoter may be applied as a
film surrounding the final powder particle. This file increases
the adhesion of the particles to the bottle surface. Combinations
of these methods may also be used.
If a mixture of a melt flow modifier and an adhesion
promoter is used to form the non-tacky powder particles, this
mixture is first melt blended in any apparatus known to those
skilled in this art as a plastograph or a single screw compounding
extruder or a mixing extruder or a twin screw melt extruder. This
extrudate is then cooled in air or water to form a solid composi-
tion. This solid composition is then formed into a powder using
- 20 -
llZ2;347
such apparatus as a knife edge chopping mill or an impact mill.
This second powder composition is then dry blended
with the first powder composition by any means known to tnose
skilled in this art. The blended powders are then comminuted
into a fine powder at temperatures below the embrittlement
temperature of the B block portion of the thermoplastic elastomer.
The dry blended powder composition may, for example, be added to
an impact pulverizer where the powders are ground using liquid
nitrogen as a cooling medium.
The non-tacky powder particles, comprising the melt
flow modifier and possibly the adhesion promoter, and the tacky
powder particles may be first dry blended and then comminuted, or
preferably, they may be dry blended and comminuted simultaneously
by, for example, dry blending the two kinds of particles in an
impact pulverizer.
Since the embrittlement temperature of the thermoplastic
elastomer is generally less than -30, down to less than -125C.,
the powder mixture should be comminuted at temperatures generally
less than -30, and preferably less than -125C.
The particle size of this powder composition may be
generally from 50 to 300, and preferably from 100 to 200 micro-
meters. The lower limit of particle size is based principally
- upon the economics of low temperature grinding whereas the upper
limit is set because of the need to achieve smooth coating and
ease of application with finer powders.
The present process may be carried out in a batch,
; continuous, or semi-continuous manner as described.
The powder particles produced according to the present
invention are generally useful in any application where good melt
flow is needed under zero shear conditions. Such applications
- 21 -
llZZ347
.
include roto-casting and coating of containers, particularly
glass bottles.
Although the powder particles thus produced are
generally useful in any application where good melt flow is
needed under zero shear conditions, they are particularly useful
for coating glass bottles to render them fragment retentive
and reusable.
The first coating of powder particles is applied to a
glass container such as a glass'bottle which is clean and dry.
The bottle can be coated with a lubricity size. Such sizes are
well known to those skilled in this art. They include poly-
ethylene, tin compounds, and titanium compounds.
The surface of the bottle to be sprayed can be vigorously
scrubbed with a warm water solution containing cleaning agent.
The bottle can then be thoroughly rinsed with warm tap water and
then followed with an acetone rinse to remove the water. The
bottles are then air dried.
The powder particles which are used for the basecoat
should also be thoroughly dried before use. The powder particles
are preferably dried for about ten hours in a vacuum oven at
about room temperature.
The powder particles may be applied by any means known
to those skilled in this art. For example, the powder particles
may be applied by electrostatic spraying, or fluidized bed.
Electrostatic spraying is preferred and the following description
of the coating process involves the use of electrostatic spraying.
The bottles are first placed in an oven for the purpose
of preheating. The temperature used in the preheat oven depends
upon the composition of the powder particles that will be sprayed.
Temperatures generally from 100 to 350, and preferably from 150
to 180~C. can be employed.
- 22 -
1122347
The amount of time the bottles are in the preheat oven
also depends upon the composition of the powder particles that -
will be sprayed onto the bottles. Residence times of generally
from O.S to 40, and preferably from 10 to 20 minutes can be
employed.
While the powder particles are being sprayed onto the
container, the container can be gently turned by a low speed
stirring motor. ~hen the container is sufficiently coated with ',
the powder particles, it is removed for baking. At this point,
the preheated container still looks white and powdery. It is
fused but not melted at this point.
The pressure which is required to feed the powder
particles through the electrostatic spraying gun is dependent
upon the stability rating of the powder particles. The powder
particle stability rating is a qualitative rating and ranges
from 1 to 5 with a powder having a rating of 1 defined as a free
flowing powder having no lumps and capable of being stored without
agglomeration. A powder having a rating of 2 is defined as one
which has lumps which can be broken up with mild agitation. A
powder having a rating of 3 is defined as one which has lumps
- which can be broken up only with violent agitation. A powder
having a rating of 4 is defined as one which contains large
lumps which cannot be broken up even with violent agitation.
A powder having a rating of 5 is defined as a completely
coalesced lump of polymer.
The powder particles of the present invention have
powder stability ratings of generally less than 3.0, and
preferably less than 1.5.
When the powder stability rating approaches 1, the
pressure within the electrostatic spray gun is relatively
1122347
uniform whereas when the powder stability rating approaches 5,
the pressure within the feed system fluctuates due to the
blocking caused by the larger par~icles.
After being sprayed, the glass bottle is placed in an
oven which is at a temperature of generally from 180 to 300,
and preferably from 215 to 235C. for generally from 1 to 40,
and preferably from 15 to 25 minutes.
The bottle is then removed from the oven and allowed
to air cool to room temperature: The weight of powder particle
that is coated on the glass bottle is generally at least 6 and
preferably at least 15 grams in order to achieve a glass fragment
retention of at least 90% on a 64 fluid ounce bottle which weighs
approximately 830 grams.
The amount of powder composition needed to achieve a
particular glass fragment retention level varies with the kind
of thermoplastic used as well as with the relative amounts of
thermoplastic elastomer and melt flow modifier.
When a second coating is to be applied, the bottle is
then again preheated at an oven temperature of generally from
60 to 350, and preferably from 100 to 120C. for 0.5 to 30, and
preferably from 10 to 20 minutes.
T~e topcoat comprises at least one synthetic resin.
The synthetic resins useful in the present invention are selected
from those having abrasion resistance, wet and dry scratch
resistance, chemical resistance, oil resistance, weather resistance
and clarity. Such resins include epoxy resins, polyurethanes,
polycarbonates, polyesters, polystyrenes, cellulosic resins such
as cellulose acetate, and cellulose nitrate, polyvinyl chloride,
polyamides, fluorocarbons, acrylic homopolymers and copolymers.
Acrylic homopolymers and copolymers are preferred for
- 24 -
1122347
use in the present invention. The term acrylic resin as used
herein includes any polymer, whether thermosetting or thermo-
plastic, which is prepared by the free-radical addition poly-
merization of one or more ethylenically unsaturated monomers,
at least 40 weight percent of which is selected from the group
consisting of acrylic and methacrylic acid, alkyl, cycloalkyl,
and aralkyl esters of acrylic and methacrylic acids, wherein
the ester moiety contains from l to about 18 carbon atoms, and
the hydroxyalkyl esters of acrylic and methacrylic acids, wherein
the hydroxyalkyl moiety contains from 2 to about lO carbon atoms.
Examples of suitable alkyl, cycloalkyl, aralkyl, and
hydroxyalkyl esters of acrylic and methacrylic acids include,
among others, methyl acrylate, ethyl acrylate, isopropyl acrylate,
n-butyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, methyl
methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate,
beta-hydroxyethyl acrylate, beta-hydroxyethyl methacrylate, beta-
-hydroxypropyl acryiate, and beta-hydroxypropyl methacrylate.
The remaining 60 weight percent or less of said ethyl-
enically unsaturated monomers consists of at least one monomer
selected from the group consisting of:
(1) acrylic monomers other than those cited herein-
above, which monomers generally encompass reactive
esters of acrylic and methacrylic acids, such as
glycidyl methacrylate, 2-aminoethyl acrylate,
2-aminopropyl methacrylate, 3-aminopropyl
methacrylate, and the like;
(2) amides, alkylol amides, and alkoxyalkyl amides
of acrylic and methacrylic, and acids, wherein
the alkyl moieties contain from l to 4 carbon
atoms and the alkoxy moiety contains from l to
llZ2347
8 carbon atoms, specific examples being acrylamide,
methacrylamide, methylol acrylamide, methoxymethyl
methacrylamide, butoxymethyl acrylamide, diacetone
acrylamide, and the like;
(3) alpha, beta-ethylenically-unsaturated dicarboxylic
acids and anhydrides, such as maleic acid, maleic anhy-
dride, fumaric acid, itaconic acid, mesaconic acid,
and the like;
(4) mono- and diesters of alpha, beta-ethylenically
unsaturated dicarboxylic acids, examples of which
esters are fumaric monoethyl ester, dimethyl
itaconate, diisopropyl maleate, dicyclohexyl maleic,
maleic acid mono (beta-hydroxyethyl) esters, and
the like;
lS (5) alpha, beta-ethylenically-unsaturated nitriles,
; such as acrylonitrile, methacrylonitrile, ethacrylo-
nitrile, and the like;
(6) ~inyl aromatic compounds, such as styrene, vinyl-
-toluene, vinyl naphthalene, chlorostyrene, bromo-
styrene, and the like;
(7) monounsaturated hydrocarbons, such as ethylene,
propylene, and the like.
Acrylic copolymers which contain from 5 to 20% by weight
hydroxypropyl methacrylate, 0 to 4% by weight acrylic or meth-
acrylic acid and the remainder being styrene or a Cl to C6 alkyl
ester of acrylic or methacrylic acid is preferred.
When the preferred thermoset acrylic polymers are used
as the topcoat in the present invention, the acrylic powder
particles include a curing agent for the acrylic polymer.
Typical curing agents include multifunctional
- 26 -
2347
isocyanates such as toluene isocyanate, polyols, pclycarboxylic
acids, hydroxylcarboxylic acids, polyamines, hydroxylamines,
and other compounds known to those skilled in this art.
One such curing agent comprises a blocked triisocyanate,
prepared by reacting three moles of 1-isocyanato-3-isocyanato-
methyl-3,5,5-trimethylcyclohexane with one mole of l,l,l-tris-
(hydroxymethyl) propane in methyl isobutyl ketone followed by
blocking with methyl ethyl ketoxime.
A preferred curing agent is methylene bis cyclohexyl
diisocyanate blocked with caprolactam.
The curing agent may be present in small amounts, gen-
erally from 20 to 50, and preferably from 30 to 40~ by weight
of the synthetic resin and curing agent.
; The synthetic resin topcoat can be applied by any method
known to those skilled in this art. For example, the topcoat can
be applied as a solution or as a dispersion of the synthetic resin
in an appropriate solvent or liquid.
Alternatively, the synthetic resin topcoat can be applied
as a powder. The topcoat can be applied by a spraying or a
dipping technique.
The topcoat can contain less than 10, and preferably
from 1 to 3~ by weight of the stabilizers against oxidation and
ultraviolet light.
The bottle is then heated in a baking oven which is at
a temperature of from 150 to 350, and preferably from 175 to
200C. for generally from 0.5 to 30, and preferably from 15 to
20 minutes. The temperature must be such as to allow the topcoat
to flow out and cure.
The bottle is then cooled to substantially ambient
temperatures. These bottles are then found to be both fragment
llZZ3~7
retentive and reusable.
Bottles coated with the compositions of the present
invention are fragment retentive. By "fragment retentive"
is meant that there is a certain degree of glass retention
when a filled glass bottle is dropped according to the follow-
ing test procedure. The test bottles are weighed and then filled
with 0.1 molar citric acid/water solution from a stock solution.
Three and six-tenths percent of the volume is displaced
with a stainless steel plug of exact size so as to leave a 3.6
headspace when removed. Then 0.4 grams/fluid ounce of sodium
bicarbonate tablets are added to the bottles. The bottle is
imediately capped and allowed to equilibrate overnight at 72C.
The bottles should have a pressure of approximately 60 psi.
The pressurized bottles are then tested for fragment
retention in a bottle drop chamber. The bottle drop chamber
comprises a platform on an electrically operated lift with a
calibrated height control and a remote electrical platform
release. The platform is centered over a heavy stainless steel
plate approximately three square feet which is set in concrete.
The chamber is enclosed for safety with heavy rubberized fabric
- and a polymethyl methacrylate observation panel.
The pressurized bottles are placed sideways on the
drop platform at a height of 4 feet, the chamber is closed,
and the platform released. All pieces of glass within a 3
foot diameter circle are collected, dried and weighed. The
ratio of the final weight of the glass pieces divided by the
original bottle weight, expressed as a percentage, is the
percentage retention.
The glass bottles coated with the powder composition
of the present invention have glass frasment retention of
- 28 -
llZZ347
generally at least 50%, and preferably at least 9~.
By "reusable" is meant that the bottle coating is not
substantially removed or destroyed during the cleaning and
sterilization procedures commonly employed by carbonated
beverage bottling companies. Several tests may be designed to
determine whether a particular coating is deemed capable of
withstanding such procudures.
The coated bottles of the present invention are sub-
jected to the following test. The coating of each bottle is
slit through to the glass with a pointed razor edge knife. The
coated bottle is-then immersed in an aqueous solution comprising
4.5% by weight sodium hydroxide and 0.5% by weight sodium
phosphate tribasic. This solution is maintained at 72C. in an
insulated seven gallon tank. The tank has a thermostatically
controlled electrical heater capable of maintaining the tempera-
ture at 72 + 2C.
The bottle is removed every hour and rinsed lightly
with warm water. The slit is picked at with a fingernail to
determine the adhesion of the coating to the glass. Then a few
drops of a 50/50% by weight ethanol/water solution containing
1% by weight phenolphthalein is rubbed lightly into the slit to
determine whether any of the sodium hydroxide solution has crept
laterally under the coating from the slit. The coating is also
observed for any signs of discoloration or haziness or any other
signs of coating failure.
Coating failure is defined as either looseness of the
coating or creepage of the sodium hydroxide solution. The longer
the coated bottles can remain in the sodium hydroxide solution
without deleterious result, the better these bottles will function
- 30 as "returnable" bottles.
. .
- 29 -
112Z;347
The coated bottles of the present invention can remain
in the sodium hydroxide solution at least 1, and preferably at
least 8 hours without any sign of substantial coating looseness
or caustic creepage.
The present invention is further illustrated by the
following examples. A11 parts and percentages in the examples
as well as in the specification and claims are by weight unless
otherwise specified.
EXAMPLE 1
A composition comprising 2678.6 grams of a Solprene
thermoplastic elastomer having a number average molecular
weight of 70,000, 1589 grams of Hercules XPS 541, copolymer of
25% by weight of styrene and 75% by weight alpha methylstyrene
(approximately 65% hydrogenated), 181 grams of gamma-glycidoxy-
propyl-trimethoxy silane and 90.8 grams of tetra-bis methylene
3-(3,5-ditertiary-butyl-4-hydroxyphenyl)- propionate methane are
placed in a twin screw melt extruder at 135C. The thermoplastic
elastomer comprises a block copolymer comprising 20% styrene
having a number average molecular weight of 16,000, and 80%
hydrogènated butadiene having a number average molecular weight
of 60,000, wherein the styrene blocks are on the end of the
polymer and the hydrogenated butadiene blocks are midhlocks. The
conjugated diene is substantially completely hydrogenated, i.e.,
more than about 98% of the double bonds are saturated. The
hydrogenated butadiene mid-block contains about 84% ethylene
groups and about 16% butylene groups.
When the molten composition exits from the extruder it
is air cooled to room temperature (about 25C.) and then chopped
into a coarse powder. The powder is then re-extruded in the
same manner to obtain a more uniform composition. The extrudate
.
- 30 -
: ~ f
12Z347
is then re-ground to form a powder. rhe coarse powder is then
placed in a pulverizer and cryogenically ground using liquid
nitrogen at a temperature of about -190C. The course
powder is ground to a fine powder having a diameter of about
250 micrometers.
The particles are applied by electrostatically spraying
onto a 64 fluid ounce glass bottle which has been preheated to
about 150C. The coated bottle is then baked in a forced
convection oven at 225C. for 20 minutes until a rather smooth
coating is produced. The coated bottle is then cooled to room
temperature.
The bottle has a coating which is substantially~clear
such than one can read through the bottle, writing, which is on
normal typewritten page. The page is wrapped around the outside
of the bottle with the typed portion facing toward the inside of
the bottle.
EXAMPLE 2
A first composition comprising 2,945 grams of a
Solprene thermoplastic elastomer having a number average molecular
weight of 70,000, 1586 grams of Hercules XPS 541 random copolymer-
of 25% by weight styrene and 75% by weight alpha methylstyrene
(approximately 65% hydrogenated), 181 grams of gamma-glycidoxy-
propyl-trimethoxy silane and 91 grams of tetra-bis methylene
3-(3,5-ditertiary-butyl-4-hydroxyphenyl)-propionate methane are
' 25 placed in a twin screw melt extruder at 135C. The thermoplastic
elastomer comprises a block copolymer comprising 20% styrene
having a number average molecular weight of 16,000 and 80% hydro-
genated butadiene having a number average molecular weight of
60,000 wherein the styrene blocks are on the end of the polymer
and the hydrogenated butadiene blocks are midblocks. The
conjugated diene is substantially completely hydrogenated, i.e.,
more than about 98% of the double bonds are saturated. The
- 31 -
llZZ347
hydrogenated butadiene midblock contains about 84% ethylene
groups and about 16% butylene groups.
; When the molten composition exits from the extruder it
is air cooled to room temperature (about 25C.) and then chopped
into pellets having a length of about l/8th inch and a diameter
of about 1/8th inch.
A second composition comprising 512 grams of the
Hercules XPS 541 polymer and 21.3 grams of the silane are separately
melt blended in the extruder and then air cooled at room tempera-
ture. The solid composition is then broken into a powder using
a knife chopping mill.
The pellets of the first composition and the powder of 1.
the second composition are then placed in an impact pulverizer
and cryogenically ground using nitrogen at a temperature of about
-190C. The pellets are ground to a powder having a diameter of
less than about 250 micrometers.
The final powder particles comprise a comparatively
large tacky particle with comparatively smaller, hard, non-tacky
particles adhering thereto. The larger particles contain the
thermoplastic elastomer, melt flow modifier, adhesion promoter,
and stabilizer. The smaller particles contain the melt flow
modifier and the adhesion promoter.
The powder particles of the present invention are hard
and non-tacky and do not coalesce even after 336 hours.
A 64 fluid ounce glass bottle is vigorously scrubbed
with a warm water solution containing cleaning agent. The bottle
is then thoroughly rinsed with warm tap water and then followed
with an acetone rinse to remove the water. The bottles are air
dried and then placed in a forced convection oven which is pre-
heated to about 150C. for about 15 minutes.
, ~ . .
- 32 -
' '
'
` llZ2347
The powder particles whlch are used for the basecoat
are dried for about ten hours in a vacuum oven at about room
temperature. The powder particles are applied using a ele-tro- ¦
static spraying gun.
- The bottle is then electrostatically sprayed with 40
to 50 grams of the powder particles prepared as described above.
While the powder particles are being sprayed onto the
bottle, the bottle is gently turned by a low speed stirring
motor. When the bottle is sufficiently coated with powder
particles, it is removed for baking. At this point, the preheated
bottle still looks white and powdery. It is fused but not melted.
After being sprayed, the bottle is placed in an oven s
which is at a temperature of 225C. for 20 minutes.
The bottle is then removed from the oven and allowed to
air cool to room temperature. The weight of powder particle
that is coated on the glass bottle is 11.7 grams.
The bottle is then again preheated in preparation for
the application of the second or topcoat coating. The coated
bottle is preheated at a temperature of 115C. for 15 minutes.
The topcoat is a thermosetting acrylic polymer which
is electrostatically sprayed onto the bottle. The acrylic
polymer contains within it 28.3% by weight of methylene bis
cyclohexyl diisocyanate blocked with caprolactam.
The bottle is then cured in a baking oven which is at
a temperature of 190C. for 20 minutes. The bottle contains
19.8 grams of topcoat.
The coated~bottle is then subjected to the following
test. The coating of the bottle is slit through to the glass in
two places and the bottle is immersed in an aqueous solution
comprising 4.5% by weight sodium hydroxide and 0.5% by weight i,.; .
' J
.~ ~
1~22347
sodium phosphate tribasic. This solution is maintained at
72C. in an insulated seven gallon tank. The tank has a
thermostatically controlled electrical heater capable of main-
taining the temperature at 72 + 2C.
The bottle is removed every hour and rinsed lightly
with warm water. The slits are picked at with a fingernail to
determine the adhesion of the coating to the glass. Then a few
drops of a 50/50% by weight ethanol/water solution containing
1~ by weight phenolphthalein is~rubbed lightly into the slits to
see whether any of the sodium hydroxide solution has crept
laterally under the coating from the slits. The coating is also
observed for any signs of discoloration or haziness or any other
signs of coating failure.
The coating around both slits does not have any sign
of substantial coating looseness or caustic creepage for over 8
hours.
This bottle is found to have a fragment retention of
97.8%.
EXAMPLES 3 - 6
Example 2 is repeated with the exception of the
differences noted in Table I. In Table I, "large particle"
means the tacky particle before it is coated with the non-agglo-
merating agent. By "small particle" is meant the smaller particles
used to keep the larger particles from agglomerating.
- 34 -
'.
` ` 1~22347
TABLE I
Powder
Example Stability Large Particle (%)
No. Rating T. E. M. F. M. A. p,C Stab.D
3 1.2 58 31.2 3.8 1.9
4 1.2 56.2 30.3 3.7 1.84
1.1 52.9 31.7 3.6 1.8
6 1.1 52.9 31.7 3.6 1.8
10 Example Small Particle (~)
No. M. F. M. A P. Film Appearance
3 4.8 .2 Slightly yellow
4 7.68 .3 Slightly yellow
9.8 .2 Slightly yellow
6 10.0 0 Slightly yellow
Example Fragment Basecoat Topcoat Caustic
No. RetentionWt. (g) Wt. (g) Test
3 99.4 14.4 18.2 8
(very slight
creep)
` 4 98.9 15.2 14.7 8
10.6 17.3 6
6 98 14.1 13.2 5
A = Thermoplastic Elastomer
B = Melt Flow Modifier
C = Adhesion Promoter `
D = Stabilizer
E = Caustic Test: number of hours that the coated bottle (with
the slit) can remain in the caustic solution
without substantial loosening of the film or
substantial creepage.
.
- 35 -
.~ s
11223'~7
The principles, preferred embodiments, and modes of
operation of the present invention have been described in the
foregoing specification. The invention which is intended to
be protected herein, however, is not to be construed as limited
to the particular forms disclosed, since these are to be
regarded as illustrative rather than restrictive. Variations
and changes may be made by those skilled in this art without
departing from the spirit of the invention.
.
`:
- 36 -
