Note: Descriptions are shown in the official language in which they were submitted.
1078Z~
BACKGROUND OF THE INVENTION
Field of the Invention
This invention relates to caustic-resistant
coatings for glass, and particularly such coatings which
include a primer of a combination of an epoxy resin and
an organofunctional silane. The invention has particular-
ly valuable utility for providing clear, caustic
resistant, adherent coatings for glass containers which
strengthen the container and provide a safety factor.
Description of the Prior Art
Copolymers of alpha-olefins and alpha, beta-
ethylenically unsaturated carboxylic acids when used as
coatings for surfaces such as glass bottles, do not
change the physical appearance of the bottles. The
coatings exhibit good initial adhesion to glass, but
the adhesion deteriorates rapidly in the presence of
high humidity due to hydrophilicity. Beverage bottles
of the returnable type are sterilized in a hot caustic
solution (e.g., 5 percent NaOH, 70C.). One or two
15-minute caustic treatments have been found to destroy
the adhesion between the glass and the polymers.
In Belgian Patent 822,689, issued May 28, 1975,
improved adhesion between glass and ionic copolymers
has been achieved by priming the glass with amino- or
epoxy functional silane or epoxy resins. About five
~ 15-minute caustic treatments can be tolerated before the
- adhesion between glass and the ionic copolymer
,
deteriorates. Still further improvement in caustic
resistance, e.g., 10 to 15 treatments, is achieved by
overcoating the ionic copolymer layer with a polymeric,
;'
~ -2-
': ,
~ . 1078266
hydrophobic protective layer, e.g., nylon.
Wells ~. S. Patent 3,297,186 describes a
method of permanently sealing glass surfaces together
using an adhesive composition consisting essentially of
a major portion of an epoxy resin, a curing agent and a
minor amount of an amino-substituted alkylalkoxysilane.
There is no teaching in this patent that a polymer or
other nonsilicious material will form a strong caustic-
resistent bond to glass via this adhesive.
Kiel U. S. Patent 3,666,539 describes glass
coatings having increased permanency of adhesion and
capable of being rapidly cured at elevated temperatures.
The coatings consist essentially of at least one carboxyl
functional acrylic resin, at least one hydroxyl containing
epoxy resin and a small effective amount of an ambi-
functional epoxy reactive silane. The coating is said
to exhibit permanency of adhesion to a glass surface
when soaked in 3 percent by weight aqueous NaOH solution
- at 160F. (71C.) for a relatively short period of time.
~ 20 The acrylic compound acts as a curing agent, and the
coating provides only poor protection against caustic.
S~MMARY OF THE INVENTION
It has now been found that clear coatings on
; glass, particularly returnable glass bottles, which
exhibit improved caustic-resistance to 15-minute treat-
ments in 5 percent by wei~ht solution of NaOH at 70 to
80C. comprise, (l) a primer layer consisting
essentially of a combination of (A) an organofunctional
silane and (B) an epoxy resin containing a curing agent
taken from the group consisting of an amine and a
:
': ' ,
1~'78~6
polyamide compound where (A) and (B) are in a single
layer or in individual layers, with the proviso that the
silane layer (A) is adjacent the glass and (2) a copoly-
meric layer consisting essentially of a copolymer of
alpha-ole~ins of the fo~mula R-CH=C~, where R is a radical
selected from the class consisting of hydrogen and alkyl
radicals having from 1 to 8 carbon atoms, and alpha,
beta-ethylenically unsaturated carboxylic a.cids having
from 3 to 8 carbon atoms, said copolymeræ having from O
to 100 percent of the carboxylic acid groups ionized by
neutralization with metal ions, said metal ions having an
ionized valence of from one-to three inclusive when the
. unsaturated acid is a monocarboxylic acid and an ionized
valence of one when the unsaturated acid is a dicarbox-
; ylic acid and said metal ions being selected from the
group consisting of uncomplexed and complexed metal ions,
. said copolymer being a direct copolymer of the alpha-
olefins and the unsaturated carboxylic acid in which the
carboxylic acid groups are randomly distributed over all
molecules and in which (a) the alpha-olefin content of the
copolymer is at least 70 mol percent, based on the alpha-
~ olefin-acid copolymer, (b) the unsaturated carboxylic acid
content of the copolymer is from 0.2 to 5 mol percent,
~. based on the alpha-olefin-acid copolymer, and (c) any
9, other monomer component copolymerized in said copolymer
fJ' being monoethylenically unsaturated and being in an amount
~. of O to 29.8 mol percent, based on the alpha-ole~in-acid
copolymer.
.~ DETAILED DESCRIPTION OF THE INVENTION
The improved clear, caustic-resistant coatings
, for glass comprise (1) a primer layer consisting
'''''; :.. ~_
, .
1078;266
essentially of a combination of (A) an organofunctional
silane and (B) an epoxy resin in either a single layer,
or in individual layers with the silane layer adjacent
the glass; and (2) a copolymeric layer which is more
fully described below. A curing agent, e.g., polyamide
or amine, is present with the epoxy resin. The primer
layer(s) may be applied by any one of a number of well
known coating means such as spraying of a liquid
dispersion or solution, dipping into a solution or
dispersion, fluidized bed powder coating, electrostatic
powder spraying, etc. Such coatings meet the standard
of resisting delamination for at ~east twelve 15-minute
. treatments in 5 percent by weight caustic solution at
70 to 80C.
Suitable silane compounds useful in the primer
layer or as a separate layer are organofunctional
silanes of the formula: (RO)3Si(CH2)xR~ where RO is a
hydrolyzable alkoxy group, R being an alkyl radical of 1
to 4 carbon atoms; Rl is a functional organic group, e.g.,
/O\ HCl
NH2-, CH2-CH-CH2O-, and -NH-CH2CH2-NH-CH2-C6H4-CH=CH2;
and x is a whole number of 1 to 4. Useful silanes are
gamma-aminopropyltriethoxy silane, gamma-glycidoxy-
; propyltrimethoxy silane and N-vinylbenzylaminoethyl-
3-trimethoxysilylpropylamine hydrochloride which is
preferred.
Epoxy resins useful in combination with the
silane compounds include epichlorohydrin/bisphenol A
- types, epoxy compounds containing one or more oxirane
. .
:~ 1078Z66
o
. , / \ ,
rings, CH2-CH , e.g., cycloaliphatic epoxies, etc. The
epoxy resihs contain a curing agent. Polyamides and
amines are preferred curing agents but acid or anhydride
epoxy curing agents are useful. Amine and polyamide
curing agents include resin materials such as, for example,
primary amine functional acrylic resins. I~hen a reactive
polyamide is used, very thin primer coatings, e.g., 0.2
mil (0 .005 mm.) in thickness, perform well. When the
epoxy resins contain other type curing agents thicker
coatings are necessary (higher percentage of solids in the
dispersion). The ratio of epoxy resin to curing agent
ranges from 1:1 to 4:1 and perhaps slightly higher.
The concentration range for the aqueous
epoxy systems ranges from 7. 5 to 40 percent by weight
total solids. The degree of caustic resistance is de-
pendent on the concentration (viscosity) of epoxy resin.
Aqueous epoxv systems are preferred over organic solvent
systems and powder form for economic reasons. Aqueous
epoxy systems are better from pollution and fire hazard
standpoints. Small amounts of water soluble organic
solvents can be used in the aqueous epoxy systems, how-
ever, to enhance the wetting characteristics of the
system. Eligible water soluble organic solvents are se-
lected to be chemically inert with resoect to other
components in the primer systems.
referably the silane compound and epoxy resin
, . .
are present in a single layer. Not only is one priming
-l operation eliminated but the presence of the silane
~: I
l 3~ compound stabilizes the dispersion viscosity.
,.
--6--
, ' .
.
1078266
The primer compounds can be applied to the
glass surface over a wide range of conditions. For
example, the glass, at room temperature, preferably in the
form of a bottle, but the glass can be flat or have other
shapes, can be sprayed with a dispersion or solution of
the primer containing epoxy resin, epoxy curing agent and
an organofunctional silane; or the glass can be sprayed
with a dispersion or solution of organofunctional silane
and, preferably after drying, sprayed with a dispersion
or solution of epoxy resin or the epoxy resin can be
applied in the form of a powder. The solution tempera-
tures range from 20C. up to 70C. or more. The
concentration range of the silane compound when present
with the epoxy resin is about 0.05 to 5 percent by weight,
preferably about 2 percent by weight, based on the total
weight of dispersion. When applied separately the
organofunctional silane is present in a range of about
0.05 to 10 percent by weight, preferably about 2 percent
by weight. A wetting agent, e.g., alcohols and ethers
such as methanol, ethanol, diethylene glycol monoethyl ether,
etc. and nonionic detergents such as the Igepal~ series
sold by General Aniline and Film Company can be used in con-
junction with the epoxy dispersions. Other coating tech-
niques as previously described are also useful. The primer
layer(s) is cured to the gel point which is understood to be
to the point of solidification and not complete curing of
the primer layer(s). Curing can be conducted by using con-
vection air, e.g., 5 to 8 minutes at 205C. or 60 to 120
- seconds in an infrared oven with the surface of the quartz
; 30 heaters at 788C. The cured primer layer(s) can range in
--7--
~~" ~(~78'~;6
thickness from 0.1 to 3.0 mils (0.003 to o.o8 mm. ) .
Additives can be used in con~unction with the
epoxy resin to extend the uncured pot life of the epoxy
resln system. Additives eligible for use in practlce of
this invention include acetic acid and metal salts which
form a complex with the epoxy curing agents. Water soluble
zinc salts are preferred and zinc chloride is most pre-
ferred, because epoxy resinæ cured in the presence of zinc
salts are not discolored and because the use of zinc salts
provides an epoxy dispersion of increased viscosity more
suitably adapted as a coating composition. The zinc salts
are used in an amount of about 5 to 50 percent by weight
and, preferably, about 15 to 30 percent by weight, of the
amount of curing agent in the epoxy system.
Onto the cured primed surface of the glass is
placed a copolymer of alpha-olefins, preferably an ionic
~; copolymer powder. The copolymers can be O to 100 percent
neutralized with metal ions. Also use~ul is a blend o~
such copolymer powder and a nylon powder. Preferred
copolymers are described in U.S. Patent 3,264,272. The
copolymers may be applied in the form of a powder of 100
mesh or finer particles. Preferably the particles which
make up the powder are in the form of spherlcal-shaped
particles having an average diameter of 10 to 100 microns
and are characterized by having a surface that is rough
and is covered with hemispherical-shaped bumps about 0.1
micron in diameter at the base. The unique, spherical-
- shaped particles can be prepared by a method described in
;~ U.S. Patent No. 3,933,954.
",~..1~, ~
` `-``` 1~78;~
,
Illustrati~e o~ the polymers are copolymers
of alpha-ole~ins of the formula R-CH= ~ , where R i8
hydrogen or an alkyl radical of 1 to 8 carbon atoms; and
alpha, beta-ethylenically unsaturated carboxylic acids
having from 3 to 8 carbon atoms, and, optionally, a
noethylenlcally unsaturated monomer. Suitable olefins
include ethylene, propylene, butene-l, pentene-l, hexene-l,
heptene-l, 3-methylbutene-1, 4~methylpentene-1, etc. The
preferred olefin ~s ethylene. Although polymers o~
ole~ins having higher carbon nu~bers can be employed in
the pre~ent invention, they are not materials which are
readily obtained or a~ailable. The concentration of the
alpha-ole~in is at least 70 mol percent in the co~olymer
and is preferably greater than 80 mol percent. Exa~ples
of alpha, beta-ethylenically unsaturated carboxylic acids
are acrylic acid, methacrylic acid, ethacrylic acid,
ltaconic acid, maleic acid, fumaric acid, monoesters Or
said dicarboxylic acids, such as methyl hgdrogen maleate,
methyl hydrogen fumarate, ethyl hydrogen ~umarate and
maleic anhydride. Although maleic anhydrlde is not a
carboxylic acid in that it haB no hydrogen attached to
the carboxyl groups, it can be considered an acid ~or
the purposes of the pxesent invention because of its
chemical reactivity being that o~ an acid. Similarly~
other alpha, beta~m~noethylenically unsaturated anhydrides
o~ carboxylic acids can be employed. The preferred
unsaturæted carboxylic acids are methacrylic and
,; .
acrylic aclds. As indicated, the concentrat~on of acldic
monomer ln the copolymer is from 0.2 mol percent to
5.0 mol percent.
,... .
. _9 _
~078;~66
me copolymer base need not necessarily comprise
a two component polymer. Thus, although the olefin
content of the copolymer should be at least 70 mol percent,
more than one ole M n can be employed to provide the
hydrocarbon nature of the copolymer base. Additionally,
other copolymerizable monoethylenically un~aturated
monomer~, illustrative member~ of whlch are mentioned
below in this and the following paragraph, can be
s employed in combination with the olefin and the carboxylic
acid comonomer. The scope of base copolymer~ suitable
; for use in the present invent~on is illustrated by the
~ollowing two component examples: ethylene/acrylic acid
~-. copolymers, ethylene/methacrylic acid copolymers, ethylene/
itaconic acid copolymers, ethylene/methyl hydrogen maleate
copolymeræ, and ethylene/maleic acid copolymers, etc.
~xamples of tri-component copolymers include: ethylene/
acryl~c acid/methyl methacrylate copolymers, ethylene/
methacrylic acid/ethyl acrylate copolymer~, ethylene/
itaconic acid/methyl methacrylate copolymers, ethylene/
methyl hydrogen maleate/ethyl acrylate copolymers,
; eth~lene/methacrylic acid/vinyl acetate copolymers~
ethylene/acrylic acid/vinyl alcohol copolymers,
ethylene/propylene/acrylic acld copolymers, ethylene/
styrene/acryl~c acid copolymers, ethylene/methacryl~c
acld/acrylonitrile copolymers, ethylene/iumaric acid/
vinyl methyl ether copolymeræ, ethylene/vinyl ehloride/
acrylic acid copolymers, ethylene/vinylidene chloride/
acrylic acid copolymers, ethylene/vinyl fluoride/methacrylic
; acid copolymer~, and ethylene/chlorotrifluoroethylene/
methacryl~c acid copolymers.
~ `
, ~
--10 -
-
07B;~66
Other particularly preferred third monomerlc
components are the alkyl esters of an alpha, beta-
ethylenically unsaturated carboxylic acid of 3 to 8
carbon atoms where the alkyl radical has 4 to 18 carbon
atoms. Particularly preferred are the terpolymers
obtained from the copolymerization of ethylene,
methacrylic acid and alkyl esters of methacrylic and/or
acrylic acid with butanol.
The concentration of the third optional
component ls 0.2 to 25 mol percent, based on the weight -
of copolymer, pre~erablg from 1 to 10 mol percent.
Representative examples of the third component include
n-butyl acrylate, isobutyl acrylate, secondary butyl -
acrylate, tertiary butgl acrylate, n-butyl methacrylate,
b isobutyl methacrylate, sec-butyl methacryla~e, t~butyl
methacrylate, n~pentyl acrylate, n-pentyl methacrylate,
isopentyl acrylate, isopentyl methacrylate, n-hexyl
acrylate, n-hexyl methacrylate, 2-ethyl-hexyl acrylate,
2-ethyl-hexyl methacrylate, stearyl acrylate, stearyl
methacrylate, n-butyl ethacrylate, 2-ethyl hexyl
ethacrylate. Also, the third component includes
mono- and di-esters of 4 to 8 carbon atom dicarboxylic
acid such aæ n-butyl hydrogen maleate, sec~butyl
hydrogen maleate, isobutyl hydrogen maleate, t-butyl
hydrogen maleate, 2-ethyl hexyl hydrogen maleate, stearyl
hydrogen maleate, n-butyl hydrogen fumarate, sec-butyl
hydrogen fumarate~ isobutyl hydrogen fumarate, t-butyl
hydrogen fumarate, 2-ethyl hexyl hydrogen fumarate,
stearyl hydrogon fumarate, n-butyl fumarateg sec-butyl
~umarate, i~obuty~ fumarate, t-butyl ~umarate, 2-ethyl
,; -11-
.,.
. ~
''' ' ' '
:` 1078266
hexyl fumarate, stearyl fumarate, n-butyl maleate, sec-
butyl maleate, isobutyl maleate, t-butyl maleate, 2-
ethyl hexyl maleate, stearyl maleate. The preferred
alkyl esters contain alkyl yroups of 4 to 8 carbon
atoms. The most preferred contain 4 carbon atoms in the
alkyl ester group. Representative examples of the
most preferred esters are n-butyl acrylate, isobutyl
acrylate, n-butyl methacrylate, isobutyl methacrylate,
tertiary butyl acrylate, tertiary butyl methacrylate.
The copolymers may also, after polymerization
but prior to any ionic crosslinking, be further modified
by various reactions to result in polymer modifications
which do not interfere with the ionic crosslinking.
~alogenation of an olefin acid copolymer is an example
of such polymer modification.
The preferred base copolymers, however, are
those obtained by the direct copolymerization of ethylene
with a monocarboxylic acid comonomer.
Metal ions which are suitable in forming the
ionic copolymers employed in the present invention can be
divided into two categories, uncomplexed metal ions and
complexed metal ions. In the uncomplexed metal ions the
valence of the ion corresponds to the valence of the
metal. These metal ions are obtained from the commonly
known and used metal salts. The complexed metal ions are
, those in which the metal is bonded to more than one type
of salt group, at least one of which is ionized and at
least one of which is not. Since the formation of the
ionic copolymers requires only one ionized valence state,
it will be apparent that such complexed metal ions are
-12-
1078Z66
equally well suited in the present invention. The term
"metal ion having one or more ioni~ed valence states"
- means a metal ion having the general formula Me+nXm,
where n is the ionic charge and is at least one, X is
a nonionized group and n+m equal the valence of the
metal. The utility of complexed metal ions employed in
the formation of ionic copolymers corresponds in their
ionized valences to those of the uncomplexed metal ions.
The monovalent metals are, of course, excluded from the
class of complexed metal ions but higher valent metals
may be included depending on how many metal valences are
complexed and how many can be ionized. The preferred
metal ions are those in which all but one metal valences
are complexed and one is readily ionized. Such compounds
are in particular the mixed salts of very weak salts,
such as oleic and stearic acid, with ionizable acids,
such as formic and acetic acid.
The uncomplexed metal ions which are suitable in
forming the ionic copolymers useful in the present in-
vention, therefore comprise for the alpha-olefin-mono-
carboxylic acid copolymers, mono-, di- and trivalent
ions of metals in Groups I, II, III, IV-A and VIII of
the Periodic Table of Elements (see page 392, Handbook
of Chemistry and Physics, Chemical Rubber Publishing Co.,
37th ed.). Uncomplexed monovalent metal ions of the
metals in the stated groups are also suitable in forming
the ionic copolymers with copolymers of olefins and
ethylenically unsaturated dicarboxylic acids. Suitable
monovalent metal ions are Na+, K+, Li+, Cs+, Ag+, Hg+ and
Cu+. Suitable divalent metal ions are Be+2, Mg+2, Ca+2,
,;
-13-
;,,,
..
-` 1078266
Sr 2, Ba+2, Cu+2, Cd+2, Hg+2, Sn+2 pb+2 Fe+2 Co+2
Ni+2 and Zn+2. Suitable trivalent metal ions are Al+3,
Sc+3, Fe+3 and Y+3.
The preferred metal ions, regardless of the
nature of the base copolymer are Na+ and Zn+2. These
metals are preferred because they result in ionic co-
polymers having the best combination of improvement in
solid state properties with retention of melt
fabricability. It is not essential that only one metal
ion be employed in the formation of the ionic copolymers
and more than one metal ion may be preferred in
certain applications.
While it is not necessary that the copolymers
be neutralized, preferably they are neutralized in the
range of 10 to 50 percent. It has been found that co-
polymeric layers comprising 100 percent neutralized
copolymers are also useful. The fully neutralized
copolymeric layers may be applied as such or may result
from caustic treatment of glass bottles coated with a
;~ 20 partially neutralized copolymeric layer.
~ The melt index of the copolymer ranges from 0.1
- g./10 minutes to 500 g./10 minutes, preferably 10 to
150 g./10 minutes.
The nylon powder used in the blend with
copolymers of alpha-olefins to improve abrasion and
; heat resistance can be prepared from polycaprolactam
(6-nylon), polyhexamethylene adipamide (66-nylon),
polyhexamethylene sebacamide (610-nylon), polyhexa-
- methylene dodecamide, as well as similar aliphatic
polycarbonamides. The nylons must be capable of being
:
-14-
1078266
melted to form the protective layer, thus the lower
melting nylons are particularly useful. Crystal Clad¢i3
nylon powder sold by General Mills is useftll. This
nylon is prepared from hexamethylene diamine, sebacic
acid and another component which is believed to be a
linoleic dimer or trimer.
The blend of copolymer and nylon powder can
be prepared by dry blending the components to form a
homogeneous mixture. Melt blending the copolymer
and nylon resins prior to the production of the powder
results in a powder useful to form coatings with
properties equal to or superior to those produced from
the dry blend. In general 60 to 90 parts hy weight of
., .
copolymer powder are blended with 10 to 40 parts by
weight of nylon powder. A preferred blend is 80 parts by
weight copolymer powder and 20 parts by weight of nylon
powder.
The copolymer powder or blend with nylon
powder can be placed on the primed surface by conventional
electrostatic powder coating equipment. For flat glass
objects, such as microscopic slides used in laboratory
testing, the powder can be applied in such a manner that
a cloud of powder falls or is sprinkled onto the glass
held essentially horizontal. The copolymer powder
or blend thereof is fused by convection heating or -
infrared radiation heating above the fusing pOillt to
form continuous coatings, 4 to 12 mils (0.1 to 0.3 mm.),
preferably 8 to 10 mils (0.2 to 0.25 mm.) in thickness.
The fused ionic copolymer coating is desirably of such
thickness to retain 90 to 100 percent of the glass
-15-
~78Z~;6
., .
fragments when a bottle pressured to 60 psig (4.22 kg./
sq. cm.) is dropped 4 feet (1.22 m.) onto a metal slab.
While the coating thickness can vary, it is desirable
to keep it as thin as possible to obtain the desired
results.
A nylon protective layer can optionally be
present on the copolymer layer. In forming the protective
layer a nylon powder can be applied and fused over the
layer of copolymer, or a nylon film may be laminated to
the copolymer layer. It is desirable that the
protective layer be clear and abrasive and heat
resistant. Thickness of the protective layer is in the
order of 1.5 to 2.0 mils (0.04 to 0.05 mm.).
The present invention has particular utility in
providing returnable glass bottles for carbonated
beverages which are stronger and more resistant to
fracture on impact than glass alone and which, in case of
fracture, provide a valuable safety factor by retaining
the broken gIass. The coatings in their preferred
embodiments exhibit excellent resistance to hot caustic
treatment solutions used to sterilize returnable glass
bottles. The coatings of the present invention are also
useful on other glass items such as fluorescent light
bulbs, and protective screens for television tubes.
~ EXAMPLES OF THE INVENTION
;~ The following Examples furtller illustrate the
invention. All percentages are by weight unless otherwise
indicated. The caustic solution is a 5 percent solution
at 80C. unless otherwise indicated.
-16-
1~378~66
''
EXA~IE 1
Glass slides were primed with N-vinylbenzyl-
aminoethyl-3-trimethoxysilylpropylamine hydrochloride,
Dow Corning silane QZ-85069*J by dipping in a 2 percent
aqueous dispersion at ambient temperature for 30 seconds
followed by air drying. me primed glass slide~ were
dipped in an acetone solution of an epoxy resin of the
formula:
/0 ~ C~ OH
CH2 -cH2~o-c6H4-c-c6E4-o-cH2-cH-cH23n
i CH3
~ where n is in the range of 1 to 20, Genepoxy~ 205 General
- Mills Co., containing a reactive polyamide containing ex-
cess amine groups as a curing agentJ Versamid~ 5201 HR 65
General Mills Co. Total solids in the acetone solution
were 55 percent and the epoxy resin/curing agent weight
ratio was 1.4:1Ø The epoxy/curing agent coating was
;; cured by maintaining the slides under an infrared radiation
quartz heater manufactured by Hugo N. Cahnman Associates,
Ine., Model ES-10 (1000 wattsJ 240 volts) for about
7 minutes. While still hot the slides were dipped in an
ionic copolymer powder of a 24 percent sodium neutralized
copolymer of ethylene with 11 percent methacrylic acid
having a melt index o~ 20.4 g./10 minutes (ASTM D-1238,
Condltion E) having a ~olume average particle size of
37 microns dete~mined by a Quantimet Image Analyzing
,~'! Computer- The ionic copolymer was prepared as described
P! in Example 1 of U.S. Patent 3,933,954, issued January 20,
;~ 1976. The powder was then fused by placing the
slides under a horizontally mounted quartz heater for
`
~denctes trade mark
~:,
-17-
--= .,
1078Z66
r
about 60 seconds. The ionic copolymer coating was about
8 mils (0.20 mm) thick. The coated slides were treated
by placing them in caustic solution for fifteen minute
periods. The three-layer coating was still tenaciously
bonded to the glass after 41 fifteen-minute periods.
The above procedure was repeated except that
the epoxy layer was omitted and the ionic copolymer
coating was top coated with about a 3-mil (0.08 mm.) thick
layer of nylon powder, Crystal Clad~ EP~2100 General Mills
Company and believed to be a 610/636 copolymer. The
glass slides withstood thirteen periods of the caustic
solution.
The procedure of paragraph one above was
repeated except that the silane layer was omitted. After
the epoxy layer was cured, it delaminated from the glass
slide after only one fifteen-minute period in caustic
solution.
The procedure of paragraph one above was re-
peated except that the layer of ionic copolymer was
omitted. After the epoxy layer was cured, it withstood -;
62 fifteen-minute periods in caustic solution.
The procedure of paragraph one above was
repeated except that in lieu of the epoxy layer the
silane-treated slides were dipped in about a 12 percent
chloroform solution of a low molecular weight polyamide ;
derived from a reaction of dimer acid (aliphatic,
dibasic acid produced by the polymerization of un-
saturated fatty acids), Emerz~ 1537, Emory Industries,
air dried and coated with ionic copolymex powder. In
two fifteen-minute periods in caustic solution (70C.)
-18-
1078266
the ionic copolymer layer delaminated from the polyamide -
layer, the polyamide layer was tenaciously bonded to the
glass after 20 fifteen-minute periods in the caustic
solution.
FXAMPLE 2
Glass slides were primed with the silane
described in Example 1 and were air dried. The slides
; were then dipped in an aqueous solution of epoxy resin
of the formula:
O\ CH3 OH
CH2-CH-C~I2~O-C6H4-C-C6H4-o CH2 C 2~n
` CH3
where n is in the range of 1 to 20, General Mills Co. TS~
679~, 50 percent solids dispersion, containing a reac-
tive polyamide containing excess amine groups as a cur-
ing agent, Versamid3 5501 General Mills Co. Total
solids in the dispersion were adjusted to 15 percent.
The epoxy/curing agent weight ratio was 1.4:1Ø The
; epoxy layer was cured by maintaining the slides under
j 20 the quartz heater described in Example 1 for 2 minutes.
The slides were then dipped in the ionic copolymer powder
described in Example 1 and the powder fused as described
in that Example. The coated slides withstood at least 36
fifteen-minute periods in the hot caustic solution of
Example 1.
The above procedure was repeated except that the
ionic copolymer described in Example 1 was replaced with
an unneutralized acid copolymer powder having a melt
' index of 10g./10 minutes and containing 9.0 percent
,~ 30 methacrylic acid. The glass slides withstood at least
.. --19--
, ' ' ~
~ 1078Z66
20 fifteen-minute periods in the caustic solution
without delamination.
The above procedure was repeated except that
the silane primer layer was omitted. The glass slides
withstood only two fifteen-minute periods in the caustic
solution before delamination of the ionic copolymer
layer.
EXAMPLE 3
Glass slides were primed with the silane
described in Example 1 and were air dried. The slides
were preheated under the quartz heater of Example 1
for about 15 seconds and dipped in epoxy powder, Vitralon~
80-1005, Pratt and Lambert Company. The powder was cured
under the quartz heater for about 2 minutes. The thick-
ness of the epoxy layer was about 1.0 mil (0.025 mm.).
The slides were then dipped in the ionic copolymer powder
described in that Example. The coated slides withstood at
least 49 fifteen-minute periods in the caustic solution of
Example 1 without sign of delamination.
The above procedure was repeated except that
the silane primer layer was omitted. The glass slides
withstood four fifteen-minute periods in the caustic
solution before delamination of the ionic copolymer
layer.
EXAMPLE 4
--
Glass slides were primed with the silane
; described in Example 1 and were air dried. The slides
were then primed with an aqueous dispersion of an
epoxy resin of the formula:
; 30
~ -20-
-~ 1078266
,
O CH OH
;~ / \ , 3
CH2-CH-CH2~O-C6H4-C-C6H4 O CH2 C 2~n
CH3
where n is in the range of 1 to 20, TSX 679 General Mills Co.,
containing as the curing agent a modified amine A-100~,
General Mills Company which is a ketone blocked amine of
,, ~ Rl
~ .
, the formula -R-N=C \ and a molecular weight of
~" \R2
' 10 about 1100; functionality of about 4; equivalent weight
,~ of about 275; blocking agent: methyl isobutyl ketone.
' Total solids for the dispersion was adjusted to 16.6
percent and the epoxy-curing agent ratio was 1.26 to 1Ø
~` The epoxy layer was cured under a horizontally
xi mounted quartz heater by maintaining the slides under
;, the heater for 2 minutes. The slides were then dipped
/~ in the ionic copolymer powder described in Example 1 and
`~, the powder fused as described in that Example. The
coated slides withstood at least 2~ fifteen-minute
periods in the hot caustic solution of Example 1 without
sign of delamination.
;
The above procedure was repeated except that
the curing agent was omitted in the aqueous epoxy
dispersion. The epoxy resin was adjusted to 10 percent
~ and the epoxy layer was cured for greater than 6 minutes
`l under the quartz heater described in Example 1. The
final ionic copolymer coated slides showed signs of
delamination after four fifteen-minute periods in the
' hot caustic solution.
.:,
," O
,~ ,
-21-
;
:.
~ 1078Z~;6
.
EXAMPLE 5
Glass beverage bottles (Coca Cola returnable
bottles No. 53201) were primed with the silane described
in Example l and were air dried. The bottles were
dipped in the aqueous solution of epoxy resin as described
. in Example 2. The total solids of the epoxy resin
solution was adjusted to 25 percent and the epoxy/curing
agent ratio was 2.0 to lØ The epoxy layer was cured in
a convection air oven for 7 minutes at about 205C.
, lO The bottles were coated with the ionic copolymer as
described in Example l, and the powder was fused as
described in that Example. Cuts were made in the bottle
coatings to simulate extreme bottle abuse. The bottles
withstood 40 fifteen-minute periods in the caustic
solution (70C.) of Example l. After each period the
bottles were abused in an American Glass Research bottle
line simulator.
EXAMPLE 6
Glass beverage bottles described in Example 5
were primed with gamma-aminopropyltriethoxysilane, ~ -
- NH2-(CH213-Si-(OC2H5)3 A-llO0~ manufactured by Union
Carbide by dipping the bottles in a 2 percent aqueous
solution for 30 seconds at ambient temperature and were
air dried. The bottles were dipped in the epoxy
) ~
i, dispersion described in Example 5 and cured as described
in that Example. The bottles were preheated to 177C.
~ in a convection air oven and coated with the ionic
-~ copolymer powder described in Example l using a Gema~
:. .
electrostatic spray gun (60 kilovolts), Interrad
3 Corporation. The ionic copolymer powder was fused by
., .
-22-
, ,
... . . . . .
, ' ' .' ' ' , ,,'' : '. : ~' '' ' '
, - - :- ~ .
- -` 1078266
post heating the bottles in the infrared oven described
in Example 1 for about 45 seconds. The coatings were
about 8 mils (0.2 mm.) thick. The bottles withstood 30
fifteen-minute periods in the caustic solution of Example
1 followed each time in the AGR line simulator of Example
5 without any signs of delamination.
The above procedure was repeated except that
the epoxy layer was omitted. After undergoing seven -
caustic treatments (70C.) as indicated above, coatings
on 50 percent of the bottles delaminated from the glass,
especially in the neck area.
The procedure described in the first paragraph
of this Example except that the silane was a 2.0 percent
!, .
aqueous dispersion as described in Example l and the
epoxy layer was omitted. After undergoing nine caustic
` treatments (70~C.) as indicated above in paragraph 1
of this Example, coatings on 50 percent of the bottles
delaminated from the glass, especially in the neck area. ~ -
- EXAMPLE 7
Glass beverage bottles as described in Example
5 were primed with the silane described in Example 1 and
were air dried. The bottles were dipped in the aqueous
solution of epoxy resin as described in Example 2
-. except that the total solids (epoxy and curing agent)
was adjusted to 7.5 percent. The epoxy/curing agent ratio
was 2 to 1. The epoxy layer was cured in an infrared
radiation oven described in Example 1 for about one
minute. The bottles were then coated with the ionic
copolymer powder as described in Example 6. After
thirteen fifteen-minute periods in the caustic solution
-23-
78Z66
,..... .:
(70C.) some signs of delamination appeared in the neck ;
area of the bottles.
EXAMPLE 8
Glass beverage bottles as described in Example
5 were dipped in an aqueous epoxy dispersion as described
in Example 2 containing about 2.0 percent silane as
described in Example 1. The dispersion was adjusted to
contain about 7.5 percent epoxy resin and curing agent.
The epoxy/curing agent ratio was 2:1. The epoxy layer
.. . .
was cured as described in Example 7 followed by coating
with ionic copolymer powder as described in Example 6.
After thirteen fifteen-minute periods in caustic solution
(70C.) some signs of delamination appeared in the
, neck area of the bottles.
EXAMPLE 9
~! Glass beverage bottles as described in Example
.~ 5 were primed and cured as described in Example 7 except
that the aqueous epoxy dispersion contained silane
~ described in Example l; the total solids was 15 percent
.j
epoxy and curing agent and 2 percent silane. After
'-~ coating the bottles as described in Example 6, the bottles
., .
;,~ survived 24 fifteen-minute periods in caustic solution
(70C.) with no observable delamination.
The above procedure was repeated except that the
, epoxy dispersion was adjusted to 20 percent epoxy plus
curing agent and 2 percent silane. The bottles survived
24 fifteen-minute periods in the caustic solution (70C.)
with no observable delamination.
;- The procedure of paragraph one of this Example
was repeated except that the epoxy dispersion was adjusted
-24-
.
,, . ~ , :: . . ......................................... :
- . . : ... . . .
~ ~`` 1078Z66
to an epoxy/curing agent ratio of 1.4 to 1 (7.5 percent
epoxy plus curing agent and 2 percent silane). The
bottles survived 28 fifteen-minute periods in the caustic
solution (70C.) with no observable delamination.
~, EXAMPLE 10
Glass beverage bottles as described in Example
5 were primed with the silane as described in Example 1
and were air dried. The bottles were dipped in an
aqueous epoxy dispersion containing an epoxy compound
of the formula:
HOC~I CH2OH
CH2-CH-CH2-0~ C~- O-CH2-CH-~CH2
CH3 O
~pogen~ 401 containing an epoxy curing agent 242 manu-
factured by M and T Chemical Company. The dispersion
was adjusted to contain 40 percent epoxy plus the curing
agent. The epoxy/curing agent ratio was 1.25 to 1Ø
The epoxy layer was cured as described in Example 7.
The bottles were coated with the ionic copolymer as
described in Example 6. The bottles survived 20
f ~ fifteen-minute periods in the caustic solution (70C.)
with no observable delamination.
The above procedure was repeated except that
the epoxy dispersion was adjusted to contain 35 percent
epoxy plus the curing agent. The epoxy/curing agent
ratio was 1.25 to 1Ø Some delamination of the coatings
,, in the neck area of the bottles was noted after 12
~, fifteen-minute caustic treatment (70C.) periods.
EXAMPLE 11
"
Glass beverage bottles were coated using an
-25-
. - ~ -
' - ' - -: : '
.~--
` 1078266
aqueous dispersion of 34.96 parts of liquid epoxy resin
solution designated as Genepoxy~ 37 OH 55, General Mills
Company; 3.85 parts of silane designated as Dow Silane
~-6032~, Dow Chemical Company; 4.81 parts of a reactive
polyamid curing agent designated as Versamid~ 125, General
Mills Company; 0.71 parts of glacial acetic acid; 3.67 parts
of diethylene glycol monoethyl ether as a wetting agent;
and 52 parts of water. The epoxy/curing agent weight ratio
was 4:1 and the total solids in the dispersion were about 25
percent. The epoxy was cured as described in Example 5.
The bottles were coated with ionic copolymer as described
in Example 1, and the powder was fused as described in
Example 1.
EXAMPLE 12
-- .
Glass beverage bottles were coated using an
: aqueous dispersion of 28.27 parts of the epoxy of the pre-
, vious example; 3.60 parts of the silane of the previous
example; 5.91 parts of the epoxy curing agent of the pre-
vious example 0.56 parts of zinc chloride; 4.92 parts of
~ 20 diethylene glycol monoethyl ether; and 56.74 parts of water.
; The epoxy/curing agent weight ratio was 2.63:1 and the total
,~ solids in the dispersion were about 23.5 percent. The
epoxy was applied and fused as described in Example 11.
EXAMPLE 13
Glass beverage bottles were coated using an
aqueous dispersion of 40.7 parts of the epoxy of Example 11;
3.8 parts of the silane of Example 11; 46.6 parts of a
, primary amine of functional acrylic resin epoxy curing
- agent such as that material designated as Dow XD-7080,
.
; 30 Dow Chemical Company; and 44.2 parts of water. The
. ~ .
,,~ -26-
, . .
.. . .
i~ ~
~. .. .
1078Z66
epoxy/curing agent weight ratio was 2:1 and the total
solids in the dispersion were about 35 percent. The epoxy
. was cured and the ionic copolymer was applied and fused as
described in Example 7.
,
'~ 10
. ~
.~
,, .
'~'
'',~, ~
.
,,
,
, I .
-27-
~ ~'
'.,
.
' :. ~- - . , , ., ', .. .
- : . . . .
