Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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TITLE
ORTHOESTER-PROTECTED POLYOLS FOR
LOW VOC COATINGS
CROSS-REFERENCE TO RELATED APPLICATION
This application claims priority under 35 U.S.C. ~119 from U.S.
Provisional Application Serial No. 60/555,162 (filed March 22, 2004),
which is incorporated by reference herein as if fully set forth.
FIELD OF THE INVENTION
This invention relates to the protection of hydroxyl groups in
poly(meth)acrylates useful in the production of low volatile organic
compound content coatings using polyisocyanates for cross-linking.
BACKGROUND OF THE INVENTION
A key to refinish coatings is the ability to deliver a refinished
vehicle to the customer as quickly as possible with a maximum level of
appearance. The consumer wants to have a good-looking, repaired
vehicle as quickly as possible to minimize the inconvenience of being
without a vehicle. The repair shop wants to maximize the utilization of his
capital investment and minimize the overall labor and cost in repairing a
vehicle. Thus, productivity in the overall repair process and good
appearance are critical.
Additionally, pressures exist worldwide to develop low volatile
organic compounds ("VOC"), that is, environmentally friendly coating
systems. One key to resolving these issues is through the dramatic
reduction or elimination of solvents used in coatings. These new, low
VOC coatings need to meet key customer attributes including productivity,
appearance, and film properties while being robust, user-friendly systems.
Currently, the automotive refinish market is comprised mostly of
two-component coatings capable of curing at ambient conditions into
cross-linked, three-dimensional, thin films. These coatings are
predominantly solvent based and use hydroxyl/isocyanate curing. One
component of the system contains the hydroxyl functional species; the
other component contains the isocyanate. These components are mixed
just prior to spraying on the vehicle. These two-part coatings need to
remain at a low enough viscosity to allow for spraying over an extended
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tirr~fra~mewnd ~th~r~;-~ftev spraying, require rapid curing to a three-
dimensional network on the vehicle to maximize productivity and physical
properties.
In repairing damage such as dents to auto bodies, the original
coating in and around the damaged area is typically sanded or ground out
by mechanical means. Sometimes the original coating is stripped off from
a portion or off the entire auto body to expose the bare metal underneath.
After repairing the damage, the repaired surface is coated, preferably with
low VOC coating compositions, typically in portable or permanent low cost
painting enclosures vented to atmosphere to remove the organic solvents
from the freshly applied paint coatings in a safe manner from the
standpoint of operator health and explosion hazard. Typically, the drying
and curing of the freshly applied paint takes place within these
enclosures. Furthermore, the foregoing drying and curing steps take
place within the enclosure to prevent the wet paint from collecting dirt in
the air or other contaminants.
As these paint enclosures take' up significant floor space of typical
small auto body paint repair shops, these shops prefer to dry and cure
these paints as fast as possible. More expensive enclosures are
frequently provided with heat sources such as conventional heat lamps
located inside the enclosure to cure the freshly applied paint at
accelerated rates. Therefore, to provide more cost effective utilization of
shop floor space and to minimize fire hazards resulting from wet coatings
from solvent based coating compositions, there exists a continuing need
for fast curing coating formulations that cure under ambient conditions
while still providing outstanding performance characteristics, particularly
chip resistance, mar-resistance, durability, and appearance.
A key aspect of the productivity in refinish coatings is the ability for
physical dry. High productivity coatings need to be able to dry to the
touch very rapidly to allow for application of subsequent coats. Clears
that are used for repairing smaller spots on a damaged vehicle (spot
repair clears) need to have as low an overspray as possible to minimize
the amount of taping needed to protect the undamaged painted area.
High glass transition temperature ("T~"), higher weight average molecular
CA 02557439 2006-08-24
wo Z~eio~~~ Ct ~~,~j a~~;i~~",~~r~orm very well in these types of
productsosioosss~
because of their ability to physically dry.
To develop a lower VOC productive system, therefore, it is critical
to produce high Tg, relatively high Mw acrylics that can be used as
components of productive systems for physical dry without adversely
effecting pot life.
WO 02/10298 discloses blocking polyols with hydrolyzable silyl
groups. JP 2001-163922 describes reacting an oligomer comprising a
polyorl:hoester, either an alpha- or beta-glycol, and an ethylenic
unsaturated group with a resin having at least tvvo hydroxyl groups. WO
02/057339 describes protecting hydroxyl groups through the use of
spiroorthocarbonate groups. U.S. Patent No. 6,297,329 issued to van
den Berg et al. on October 2, 2001, discloses a coating composition
comprising a first compound comprising at least one bicyclo- or spiro-
orthoester group and a second compound comprising at least two
hydroxyl-reactive groups. U.S. Patent No. 6,045,870 issued to Noura et
al. on April 4, 2000, discloses the protection of carboxyl groups through
silylation.
It is desirable to improve physical dry and long pot life through the
use of novel polymers with protected hydroxyls. The coatings disclosed
herein are stable under anhydrous conditions but become active, or de-
block, after application via the absorption of atmospheric moisture, which
will release the initial hydroxyl groups. Once the hydroxyl group is
released, it will quickly react with the isocyanate cross-linker to develop a
three-dimensional network, and very rapid film formation will occur.
SUMMARY OF THE INVENTION
The invention relates to a coating composition wherein orthoester
groups block the hydroxyl groups of the poly(meth)acrylate. The
orthoester groups can be removed through hydrolysis in order to facilitate
cross-linking through reaction with polyisocyanate compounds. The
invention also relates to a process for curing the aforementioned coating
composition. The invention also relates to a process for coating
substrates wherein a clear coat comprising the aforementioned coating
composition is coated over a base coat. The invention also relates to a
-3-
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proves~s~mt~r~aio~Ktng trre nyaroxy groups or a poiy~metn)acryate
compound through reaction with an orthoester compound.
DETAILED DESCRIPTION OF THE INVENTION
Applicants specifically incorporate the entire content of all cited
references in this disclosure. Applicants also incorporate by reference the
co-owned and concurrently filed application Serial No. entitled
"Ketal-Protected Polyols for Low VOC Coatings."
Where a range of numerical values is recited herein, unless
otherwise stated, the range is intended to include the endpoints thereof,
and all integers and fractions within the range. It is not intended that the
scope of the invention be limited to the specific values recited when
defining a range.
In the context of this disclosure, a number of terms shall be
utilized.
The term "(meth)acrylate" denotes both acrylate and methacrylate.
The term "polydispersity" of a polymer is a ratio of MW to number
average molecular weight ("Mn").
The term "low VOC coating composition" means a coating
composition that includes the range of from 0.1 kilograms (1.0 pounds per
gallon) to 0.72 kilograms (6.0 pounds per gallon), preferably 0.3 kilograms
(2.6 pounds per gallon) to 0.6 kilograms (5.0 pounds per gallon), and
more preferably 0.34 kilograms (2.8 pounds per gallon) to 0.53 kilograms
(4.4 pounds per gallon) of the solvent per liter of the coating composition.
All VOCs are determined under the procedure provided in ASTM D3960.
In one embodiment, the present invention concerns a coating
composition comprising a poly(meth)acrylate containing at least two
hydroxyl groups blocked by hydrolyzable orthoester groups and at least
one polyisocyanate compound.
In another embodiment, the invention concerns a process for
blocking the hydroxyl groups of poly(meth)acrylates comprising thermally
reacting a poly(meth)acrylate containing at least two hydroxyl group with
at least one orthoester compound.
-4-
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wy°omcr~wa°wnsvmeam rormmg a nyaroiyzaaie ester through
reaction between at least two hydroxyl groups of a poly(meth)acrylate and
at least one orthoester compound to form hydrolyzable orthoester groups.
In one embodiment, from about 30% to 100% of hydroxyl groups are
blocked by an orthoester compound. In a preferred embodiment, an
orthoester compound blocks substantially all of the hydroxyl groups_ By
"substantially all of the hydroxyl groups" is meant vinyl ether compounds
have blocked at least 70% of the hydroxyl groups.
In a preferred embodiment, coating compositions are formulated by
first taking a poly(meth)acrylate compound containing at least two
hydroxyl groups and protecting the hydroxyl groups through an acid
catalysis reaction with at least one orthoester compound. The
etherification reaction results in a poly(meth)acrylate compound wherein
the hydroxyl groups have been blocked by orthoester groups. When
needed for use in a coating composition, the blocked poly(meth)acrylate
compound is unblocked by hydrolyzing the orthoester groups with water,
optionally in the presence of an acid catalyst, either prior to or
simultaneously with the addition of an polyisocyanate compound. The
unblocked hydroxyl groups of the poly(meth)acrylate compound can freely
react with the polyisocyanate compound to produce coating compositions
by any method known to one of ordinary skill in the art.
Non-limiting examples of poly(meth)acrylates used in the coating
composition are polymerized monomers of acrylic and methacrylic acid
esters of straight-chain or branched monoalcohols of 1 to 20 carbon
atoms. Preferred esters are alkyl acrylates and methacrylates having 1 to
12 carbons in the alkyl group such as methyl acrylate, ethyl acrylate,
propyl acrylate, isopropyl acrylate, butyl acrylate, pentyl acrylate, hexyl
acrylate, 2-ethyl hexyl acrylate, nonyl acrylate, lauryl acrylate, methyl
methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl
methacrylate, butyl methacrylate, pentyl methacrylate, hexyl
methacrylate, 2-ethyl hexyl methacrylate, nonyl methacrylate, lauryl
methacrylate, and the like. Isobornyl methacrylate and isobornyl acrylate
monomers can be used. Cycloaliphatic (meth)acrylates can be used such
as trimethylcyclohexyl acrylate, t-butyl cyclohexyl acrylate, cyclohexyl
-5-
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m~th'~~hr~ylat~; "i~t~k~t~~'n'yl methacrylate, ~-ethylhexyl methacrylate, and
the
like. Aryl acrylates and methacrylates such as benzyl acrylate and benzyl
methacrylate also can be used.
Ethylenically unsaturated monomers containing hydroxy
functionality including hydroxy alkyl acrylates and hydroxy alkyl
methacrylates, wherein the alkyl group has 1 to 4 carbon atoms, can be
used. Suitable monomers include hydroxyethyl acrylate, hydroxypropyl
acrylate, hydroxyisopropyl acrylate, 2,3-dihydroxypropyl acrylate,
hydroxybutyl acrylate, dihydroxybutyl acrylate, hydroxyethyl methacrylate,
hydroxypropyl methacrylate, hydroxyisopropyl methacrylate, hydroxybutyl
methacrylate, dihydroxypropyl methacrylate, dihydroxybutyl methacrylate
and the like, and mixtures thereof. Hydroxy functionality may also be
obtained from monomer precursors, for example, the epoxy group of a
glycidyl methacrylate unit in a polymer. Such an epoxy group may be
converted, in a post polymerization reaction with water or a small amount
of acid, to a hydroxy group.
Suitable other olefinically unsaturated comonomers that can be
used include acrylamide and methacrylamide and derivatives such as
alkoxy methyl (meth) acrylamide monomers, such as methacrylamide, N-
isobutoxymethyl methacrylamide, and N-methylol methacrylamide;
malefic, itaconic, and fumaric anhydride and its half and diesters; vinyl
aromatics such as styrene, alpha methyl styrene, and vinyl toluene; and
polyethylene glycol monoacrylates and monomethacrylates.
Other functional monomers such as itaconic or malefic anhydride,
the half ester thereof, acrylonitrile, allyl methacrylate, aceto acetoxyethyl
methacrylate, methylacryl amidoglycolate methyl ether, ethylene urea
ethyl methacrylate, 2- acrylamide-2 methyl propane sulfonic acid, trialkoxy
silyl ethyl methacrylate, reaction products of mono epoxy esters or mono
epoxy ethers with alpha-beta unsaturated acids, and reaction products of
glycidyl (meth)acrylate with mono functional acids up to 22 carbon atoms
can be used.
Preferably, the M" of the poly(meth)acrylate is in the range of from
about 200 to about 50,000. More preferably, the M" of the
poly(meth)acrylate is in the range of from about 300 to about 20,000.
-6-
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~ve~n°w~or~ pre~~rabiy; the M~ of the poly(meth)acrylate is in the
range of
from about 500 to about 6,000. All molecular weights referred to herein
are determined by gel permeation chromatography ("GPC") using a
polystyrene standard.
The poly(meth)acrylate preferably includes in the range from 2 to
200, more preferably in the range from 2 to 50, and most preferably in the
range from 2 to 20 hydroxyl groups per poly(meth)acrylate compound.
In a preferred embodiment, the poly(meth)acrylate has a
polydispersity in the range of from about 1.5 to about 10Ø In a more
preferred embodiment, the poly(meth)acrylate has a polydispersity in the
range of from about 1.5 to about 5Ø In an even more preferred
embodiment, the poly(meth)acrylate has a polydispersity in the range of
from about 1.5 to about 3Ø
The polyisocyanate compound of the coating composition includes
one or more cross-linking agents having at least two isocyanate groups.
Any of the conventional aromatic, aliphatic, cycloaliphatic, isocyanates,
trifunctional isocyanates, and isocyanate functional adducts of a polyol
and a diisocyanate can be used. Typically useful diisocyanates are 1,6-
hexamethylene diisocyanate, isophorone diisocyanate, 4,4'-biphenylene
diisocyanate, toluene diisocyanate, bis cyclohexyl diisocyanate,
tetramethylene xylene diisocyanate, ethyl ethylene diisocyanate, 2,3-
dimethyl ethylene diisocyanate, 1-methyltrimethylene diisocyanate, 1,3-
cyclopentylene diisocyanate, 1,4-cyclohexylene diisocyanate, 1,3-
phenylene diisocyanate, 1,5-naphthalene diisocyanate, bis-(4-
isocyanatocyclohexyl)-methane, and 4,4'-diisocyanatodiphenyl ether.
Typical trifunctional isocyanates include triphenylmethane
triisocyanate, 1,3,5-benzene triisocyanate, and 2,4,6-toluene
triisocyanate. Trimers of diisocyanates also can be used, such as the
trimer of hexamethylene diisocyanate, which is supplied by Bayer Corp.,
Pittsburgh, Pa., under the trademark Desmodur~ N 3300A. Other suitable
polyisocyanates from Bayer Corp. include Desmodur~ N 3390A BA/SN
and Z 4470BA polyisocyanates.
The relative amount of cross-linking agent used in the coating
composition is adjusted to provide a molar equivalent ratio of
-7-
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~'N'~'Ol~'dH-~NfW'~ i~rfi'hw range of from about 0.5 to about 5, preferably in
the
range of from about 0.7 to about 3, and more preferably in the range of
from about 0.85 to about 2.
The coating composition is suitable for use as a clear or pigmented
composition. The coating composition can be used as a monocoat, as a
basecoat, or as a primer.
The coating composition can include additional components such
as solvents, catalysts, pigments, fillers, and conventional additives.
Some of the suitable solvents include aromatic hydrocarbons, such
as petroleum naphtha or xylenes; esters, such as, butyl acetate, t-butyl
acetate, isobutyl acetate or hexyl acetate; and glycol ether esters, such as
propylene glycol monomethyl ether acetate. The amount of organic
solvent added depends upon the desired solids level as well as the
desired amount of VOC of the composition. If desired, the organic solvent
may be added to both the components of the coating composition.
The coating composition preferably includes a catalytic amount of
a catalyst for accelerating the curing process. Generally, in the range of
about 0.001 % to about 5%, preferably in the range of from about 0.002%
to about 3%, more preferably in the range of from about 0.005% to about
1.5% of the catalyst is utilized, all in weight percent based on the total
weight of cross-linkable and cross-linking component solids. A wide
variety of catalysts can be used, such as tin compounds, including dibutyl
tin dilaurate and dibutyl tin diacetate, and tertiary amines such as
triethylenediamine. These catalysts can be used alone or in conjunction
with carboxylic acids, such as acetic acid. One of the commercially
available catalysts, sold under the trademark Fastcat~ 4202 dibutyl tin
dilaurate (Elf Atochem North America, Inc., Philadelphia, Pa.), is
particularly suitable.
Hydrolyzing the protective group leads to the recovery of the
original poly(meth)acrylate with hydroxyl groups available for cross-
linking. Hydrolysis can occur in water, optionally in the presence of an
acid catalyst. Suitable acids, for example, include acetic acids and the
like, phosphorous and phosphoric acids and their esters, hydrochloric
acid, perchloric acid, hydrobromic acid, sulfuric acid and its half-esters,
_g_
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'sfxlfio~h'id v'bid~°'I'r~C~'vb'd~cylbenzenesulfonic acid, and
compounds that
generate acids upon hydrolysis such as, for example, POC13, SOCI2, and
PCIS.
The hydrolysis reaction can occur before or concurrently with the
addition of cross-linker. Preferably, the blocked poly(meth)acrylates are
unblocked, and the hydroxyl groups thus recovered, concurrently with the
addition of cross-linker. It is to be understood that as the water contacts
the orthoester groups present in the composition, the orthoester groups
will start to hydrolyze, eventually leading to cross-linking of the
composition. The water may be introduced in a variety of ways. For
example, especially in the case of a coating, the water may be introduced
into the uncross-linked or cross-linking (while the cross-linking is taking
place) coating by absorption from the air. Absorption is very convenient
for making an uncross-linked coating composition that is stable until
exposed to (moist) air. Alternatively, water may be mixed in a mixing
head or spray-mixing head (for a coating) just before cross-linking is to
take place.
The coating composition can contain one or more coloring or
special effect producing pigments. Examples of inorganic or organic
coloring pigments include titanium dioxide, micronized titanium dioxide,
iron oxide pigments, carbon black, azo pigments, phthalocyanine
pigments, quinacridone pigments, and pyrrolopyrrol pigments. Examples
of special effect producing pigments include aluminum flake, copper
bronze flake, and other metal flakes; interference pigments such as, for
example, metal oxide coated metal pigments, for example, titanium
dioxide coated or mixed oxide coated aluminum, coated mica such as, for
example, titanium dioxide coated mica and graphite special effect
pigments.
Examples of fillers include silicon dioxide, aluminium silicate,
barium sulfate, and talcum.
The coating composition may also include conventional additives
such as wetting agents; leveling and flow control agents, for example,
BYK~ 320 and 325 (high molecular weight polyacrylates; BYK-Chemie
USA Inc., Wallingford, Conn.), BYK~ 347 (polyether-modified siloxane),
_g_
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"a'nd°'gel'~'"'~~306"°C'~cil~°~~Nfd'i--modified
dimethylpolysiloxane); rheology
control agents such as fumed silica; defoamers; surfactants; and
emulsifiers to help stabilize the composition. Other additives that tend to
improve mar resistance can be added, such as silsesquioxanes and other
silicate-based micro-particles. Such additional additives will, of course,
depend on the intended use of the coating composition. Any additives
that would adversely affect the clarity of the cured coating will not be
included when the composition is used as a clear coating. The foregoing
additives may be added to either component or both depending upon the
intended use of the coating composition.
To improve weatherability of the coating, from about 0.1 to about 5
weight percent, preferably from about 0.5 to about 2.5 weight percent,
and more preferably from about 1 to about 2 weight percent of ultraviolet
light stabilizers screeners, quenchers,and antioxidants can be added to
the composition, the percentages being based on the total weight of the
binder and cross-linking components solids. Typical ultraviolet light
screeners and stabilizers include the following:
Benzophenones such as hydroxy dodecycloxy benzophenone, 2,4-
dihydroxy benzophenone, and hydroxy benzophenones containing
sulfonic acid groups.
Benzoates such as dibenzoate of diphenylol propane and tertiary
butyl benzoate of diphenylol propane.
Triazines such as 3,5-dialkyl-4-hydroxyphenyl derivatives of
triazine and sulfur containing derivatives of dialkyl-4-hydroxy phenyl
triazine and hydroxy phenyl-1,3,5-triazine.
Triazoles such as 2-phenyl-4-(2,2'-dihydroxy benzoyl)-triazole and
substituted benzotriazoles such as hydroxy-phenyltriazole.
Hindered amines such as bis(1,2,2,6,6-entamethyl-4-piperidinyl
sebacate) and di[4(2,2,6,6-tetramethyl piperidinyl)]sebacate; and any
mixtures of any of the above.
Preferably, the hydrolyzable orthoester group is an orthoformate
group. Even more preferably, the hydrolyzable orthoester group has the
following chemical structure:
-10-
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R~ ~ ~Rs
~C O
R2 O
wherein R~ and R2 are, independently, alkyl substituents of 1 to 6 carbon
atoms or cyclic substituents of 5 to 7 atoms; and R3 is H, an alkyl
substituent of 1 to 6 carbon atoms, or an aromatic substituent.
In another embodiment, the invention concerns a process for
curing coating composition comprising thermally reacting a
poly(meth)acrylate containing at least two hydroxyl groups with at least
one orthoester compound, hydrolyzing the product of the thermal reaction
step to unblock the poly(meth)acrylate containing at least two hydroxyl
groups, and reacting the unblocked poly(meth)acrylate containing at least
two hydroxyl groups with at least one polyisocyanate compound.
Preferably, the orthoester compound has the following chemical
structure:
R~ ~ ~Rs
~C O R4
R2 O
wherein R~ and R2 are, independently, alkyl substituents of 1 to 6 carbon
atoms or cyclic substituents of 5 to 7 atoms; R3 is H, an alkyl substituent
of 1 to 6 carbon atoms, or an aromatic substituent; and R~. is an alkyl
substituent of 1 to 6 carbon atoms. Preferable orthoester compounds
include triethylorthoformate, trimethylorthoformate,
triethylorthopropionate, trimethylorthopropionate, and 2-ethoxy-1,3-
dioxalane. In a preferred embodiment, the orthoester compound is
triethylorthoformate.
The blocking reaction is thermal, which means performed by heat
without the need for a catalyst. A catalyst may be used, however, if
desired. To block the hydroxyl groups of a poly(meth)acrylate compound,
the poly(meth)acrylate is heated with an excess of an orthoester
compound. The thermal reaction preferably occurs in the temperature
range of from about 70°C to about 200°C and even more preferably
-11-
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~~o~bl#rs~~'iff~'th~b'-tdr~1'~'dr'~fi~r'e range of from about 110"C; to about
150°C.
The hydroxyl groups are blocked, for example, by the following reaction:
R~- \ /R3 R~-O R3
/C-O-R4 -E HO~C/Polyol H~ \C O~ ~Pol of
Y
Ra-O Ha R2-O
wherein R~ and R2 are, independently, alkyl substituents of 1 to 6 carbon
atoms or cyclic substituents of 5 to 7 atoms; R3 is H, an alkyl substituent
of 1 to 6 carbon atoms, or an aromatic substituent; and R4 is an alkyl
substituent of 1 to 6 carbon atoms. "Polyol" represents the
poly(meth)acrylate backbone.
Blocking the hydroxyl groups of the poly(meth)acrylate compound
can reduce the viscosity of the coating composition, thus allowing for the
preparation of higher solids, lower VOC coating compositions. If
necessary, the viscosity of the blocked poly(meth)acrylate can be
adjusted using, for example, ethyl acetate.
In an alternative embodiment, coatings of the invention can
comprise at least one of a spiroorthocarbonate compound and an amide
acetal compound. Spiroorthocarbonate compounds are described in co-
pending, co-owned application Serial No. 60/261,450, and amide acetal
compounds are described in co-pending, co-owned application Serial No.
60/509,885.
Preferably the spiroorthocarbonate compound has the following
chemical structure:
R ~ ~ ~s
O O
wherein R5 and R6 are, independently, hydrocarbylene or substituted
hydrocarbylene bridging groups that have at least two bridging carbon
atoms. It is preferred that there independently be 2 or 3 atoms in each
bridge between oxygen atoms. By hydrocarbylene is meant a group
containing only carbon and hydrogen that has two free valences to carbon
-12-
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f~at~ofhi's;~~~r4c~°jbn~hlt~re~fv~l~nces are not to the same carbon
atom. By
substituted hydrocarbylene is meant one or more hydrogen atoms are
substituted for by a functional group that does not interfere with the
desired reactions of, or the formation of, the compound involved. Suitable
functional groups include halo, ether including alkoxy, hydroxyl, etc.
Preferred groups for R5 and R6 each independently have the
formula -CR~R$-CR9R~o-(CR~~R1~)~-, wherein n is 0 or 1, and each of R~-
R12 independently is hydrogen, hydrocarbyl, or substituted hydrocarbyl,
provided that any two of R7-R12 vicinal or geminal to each other taken
together may form a ring. In one preferred form R5 and R6 are the same.
Independently preferred groups for R7-R~2 are hydrogen; alkyl, especially
alkyl containing 1 to 10 carbon atoms, more preferably methyl or ethyl;
and hydroxyaklyl, especially hydroxymethyl. Substitution patterns for
specific preferred compounds are given in Table 1.
Table 1
Com R5 R6
ound
R~ R$ R9 Rio R~,R~~n R~ R$ R9 Rio R~~R~2n
A CH3 H H H H H 1 CH3 H H H H H 1
B H H CH20H C~HS H H 1 H H CH~OH C2H5 H H 1
C H H H H - - 0 H H CH~OH C~HS H H 1
D H H H H H H 1 H H CH~OH CZHS H H 1
E H H H H H H 1 H H H H H H 1
F CH3 H H H - - 0 CH3 H H H - - 0
G H H H H - - 0 H H H H - - 0
H H H n-C4H9 C~HS H H 0 H H n-C4H9 C~HS H H 0
I H H n-CBH~~H - - 0 H H n-CBH~~H - - 0
Preferably, the amide acetal compound has the following chemical
structure:
R1~ R1s
R16 R19
~N
R15 R20
R14 O I ~O R21
wherein R13-R21 are, independently, hydrogen, C1 to C22 alkyl, C1 to C2o
alkenyl, C1 to C2o alkynyl, C1 to C2o aryl, C~ to C2o alkyl ester, or C~ to
C2o
-13-
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~ta~ral~i~il~~~~~rkie~~p~~~li~l~~~~l~k~~;~~~lkenyl, alkynyl, aryl, or aralkyl
each optionally
having at least one substituent selected from the group consisting of halo,
alkoxy, nitro, amino, alkylamino, dialkylamino, cyano, alkoxy silane and
amide acetal (difunctional), and carbamoyl.
In a further alternative embodiment, coatings of this invention can
comprise at least one of a conventional acrylic polymer, a polyester, a
reactive oligomer, a dispersed acrylic polymer, an aldimine or ketimine,
and a polyaspartic ester.
The conventional acrylic polymer suitable for use in the present
invention can have a GPC MW exceeding 5,000, preferably in the range of
from 5,000 to 20,000, more preferably in the range of 6,000 to 20,000,
and most preferably in the range of from 8,000 to 12,000. The Tg of the
acrylic polymer varies in the range of from 0°C to 100°C,
preferably in the
range of from 30°C to 80°C.
The acrylic polymer suitable for use in the present invention can be
conventionally polymerized from typical monomers, such as alkyl
(meth)acrylates having alkyl carbon atoms in the range of from 1 to 18,
preferably in the range of from 1 to 12, and styrene and functional
monomers such as hydroxyethyl acrylate and hydroxyethyl methacrylate.
The polyester suitable for use in the present invention can have a
GPC MW exceeding 1,500, preferably in the range of from 1,500 to
100,000, more preferably in the range of 2,000 to 50,000, still more
preferably in the range of 2,000 to 8,000, and most preferably in the range
of from 2,000 to 5,000. The Tg of the polyester varies in the range of from
-50°C to 100°C, preferably in the range of from -20°C to
50°C.
Suitable polyesters can be conventionally polymerized from
suitable polyacids, including cycloaliphatic polycarboxylic acids, and
suitable polyols, which include polyhydric alcohols. Examples of suitable
cycloaliphatic polycarboxylic acids are tetrahydrophthalic acid,
hexahydrophthalic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-
cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 4-
methylhexahydrophthalic acid, endomethylenetetrahydrophthalic acid,
tricyclodecanedicarboxylic acid, endoethylenehexahydrophthalic acid,
camphoric acid, cyclohexanetetracarboxylic acid, and
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WO 2005/092934 PCT/US2005/008887
"cyc~cHb~~~n'e~tetl~~~~~f~~c~~ylic acid. The cycloaliphatic polycarboxylic
acids
can be used not only in their cis but also in their trans form and as a
mixture of both forms. Examples of suitable polycarboxylic acids, which,
if desired, can be used together with the cycloaliphatic polycarboxylic
acids, are aromatic and aliphatic polycarboxylic acids, such as, for
example, phthalic acid, isophthalic acid, terephthalic acid,
halogenophthalic acids, such as, tetrachloro- or tetrabromophthalic acid,
adipic acid, glutaric acid, azelaic acid, sebacic acid, fumaric acid, malefic
acid, trimellitic acid, and pyromellitic acid.
Suitable polyhydric alcohols include ethylene glycol, propanediols,
butanediols, hexanediols, neopentylglycol, diethylene glycol,
cyclohexanediol, cyclohexanedimethanol, trimethylpentanediol,
ethylbutylpropanediol, ditrimethylolpropane, trimethylolethane,
trimethylolpropane, glycerol, pentaerythritol, dipentaerythritol,
tris(hydroxyethyl) isocyanate, polyethylene glycol, and polypropylene
glycol. If desired, monohydric alcohols, such as, for example, butanol,
octanol, lauryl alcohol, ethoxylated, or propoxylated phenols may also be
included along with polyhydric alcohols. The details of polyester suitable
for use in the present invention are further provided in the U.S. Patent No.
5,326,820. One commercially available polyester, which is particularly
preferred, is SCD~-1040 polyester, which is supplied by Etna Products
Inc., Chagrin Falls, Ohio.
Useful reactive oligomers are covered in U.S. Patent No.
6,221,494. Non-alicyclic (linear or aromatic) oligomers can also be used,
if desired. Such non-alicyclic-oligomers can be made by using non-
alicyclic anhydrides, such as succinic or phthalic anhydrides, or mixtures
thereof. Caprolactone oligomers described in U.S. Patent No. 5,286,782
can also be used.
Typical useful dispersed acrylic polymers are prepared by
dispersion polymerizing at least one vinyl monomer in the presence of a
polymer dispersion stabilizer and an organic solvent. The polymer
dispersion stabilizer may be any of the known stabilizers used commonly
in the field of dispersed acrylic polymers. These dispersed acrylic
polymers are covered in U.S. Patent No. 5,763,528.
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WO 2005/092934 PCT/US2005/008887
=~SY~~it~~ble'~~'It~~rn~i~r~~s~''imay be prepared firom aldehydes such as
acetaldehyde, formaldehyde, propionaldehyde, isobutyraldehyde, n-
butyraldehyde, heptaldehyde, and cyclohexyl aldehydes by reaction with
amine. Representative amines that may be used to form the aldimine
include ethylene diamine, ethylene triamine, propylene diamine,
tetramethylene diamine, 1,6-hexamethylene diamine, bis(6-
aminohexyl)ether, tricyclodecane diamine, N,N'-dimethyldiethyltriamine,
cyclohexyl-1,2,4-triamine, cyclohexyl-1,2,4,5-tetraamine, 3,4,5-
triaminopyran, 3,4-diaminofuran, and cycloaliphatic diamines.
Suitable polyaspartic esters are typically prepared by the reaction
of diamines such as isophorone diamine with dialkyl maleates such as
diethyl maleate.
The foregoing polyaspartic ester and selected aldimines are
supplied commercially under the trademark Desmophen~ amine co-
reactants by Bayer Corp.
Suitable ketimines are typically prepared by the reaction of ketones
with amines. Representative ketones, which may be used to form the
ketimine, include acetone, methyl ethyl ketone, methyl isopropyl ketone,
methyl isobutyl ketone, diethyl ketone, benzyl methylketone, diisopropyl
ketone, cyclopentanone, and cyclohexanone. Representative amines
which may be used to form the ketimine include ethylene diamine,
ethylene triamine, propylene diamine, tetramethylene diamine, 1,6-
hexamethylene diamine, bis(6-aminohexyl)ether, tricyclodecane diamine,
N,N'-dimethyldiethyltriamine, cyclohexyl-1,2,4-triamine, cyclohexyl-
1,2,4,5-tetraamine, 3,4,5-triaminopyran, 3,4-diaminofuran, and
cycloaliphatic diamines. Preparation and other suitable imines are shown
in U.S. Patent No. 6,297,320.
In another embodiment, the invention concerns a process for
coating a substrate comprising applying a base coat to the substrate,
applying a clear coat over the base coat wherein the clear coat comprises
a poly(meth)acrylate containing at least two hydroxyl groups blocked by
hydrolyzable orthoester groups and at least one polyisocyanate
compound, hydrolyzing the orthoester groups of the poly(meth)acrylate
containing at least two hydroxyl groups, and cross-linking the unblocked
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'~~Ij~(~ni~ethi')abiyi~~~~''~iic~~'''the hydrolyzing step through reaction
with at
least one polyisocyanate compound.
The coating composition can be supplied in the form of a two-pack
coating composition. Generally, the cross-linkable component and the
cross-linking component are mixed; typically just prior to application to
form a pot mix. The mixing can take place though a conventional mixing
nozzle or separately in a container. A layer of the pot mix generally
having a thickness in the range of 15,um to 200,um is applied over a
substrate, such as an automotive body or an automotive body that has
precoated layers, such as electrocoat primer. The foregoing application
step can be conventionally accomplished by spraying, electrostatic
spraying, roller coating, dipping, or brushing the pot mix over the
substrate. The layer after application is typically dried to reduce the
solvent content from the layer and then cured at a temperature ranging
from ambient to about 204°C. Under typical automotive original
equipment manufacturer ("OEM") applications, the dried layer of the
composition can be typically cured at elevated temperatures ranging from
about 60°C to about 160°C in about 10 to 60 minutes. Preferably,
for
automotive refinish applications, curing can take place at about ambient
to about 60°C, and for heavy duty truck body applications, curing can
take
place at about 60°C to about 80°C. The cure under ambient
conditions
occurs in about 30 minutes to 24 hours, generally in about 30 minutes to
4 hours to form a coating on the substrate having the desired coating
properties. It is further understood that the actual curing time can depend
upon the thickness of the applied layer, the cure temperature, humidity,
and on any additional mechanical aids, such as fans, that assist in
continuously flowing air over the coated substrate to accelerate the cure
rate. It is understood that actual curing temperature would vary
depending upon the catalyst and the amount thereof, thickness of the
layer being cured, and the amount of the cross-linking component utilized.
The suitable substrates for applying the coating composition
include automobile bodies; any and all items manufactured and painted
by automobile sub-suppliers; frame rails; commercial trucks and truck
bodies, including but not limited to beverage bodies, utility bodies, ready
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''rr~'ix''~'cw~r~~t~vd~i~~~fy'"v~'~f~l'icle bodies, waste hauling vehicle
bodies, and
fire and emergency vehicle bodies, as well as any potential attachments
or components to such truck bodies, buses, farm, and construction
equipment; truck caps and covers; commercial trailers; consumer trailers;
recreational vehicles, including but not limited to, motor homes, campers,
conversion vans, vans, pleasure vehicles, pleasure craft snow mobiles, all
terrain vehicles, personal watercraft, motorcycles, boats, and aircraft.
The substrate further includes industrial and commercial new construction
and maintenance thereof; cement and wood floors; walls of cdmmercial
and residential structures, such office buildings and homes; amusement
park equipment; concrete surfaces, such as parking lots and drive ways;
asphalt and concrete road surface; wood substrates; marine surfaces;
outdoor structures, such as bridges; towers; coil coating; railroad cars;
printed circuit boards; machinery; OEM tools; signage; fiberglass
structures; sporting goods; and sporting equipment.
EXAMPLES
The present invention is further defined in the following Examples.
It should be understood that these Examples, while indicating preferred
embodiments of the invention, are given by way of illustration only. From
the above discussion and these Examples, one skilled in the art can
ascertain the preferred features of this invention, and without departing
from the spirit and scope thereof, can make various changes and
modifications of the invention to adapt it to various uses and conditions.
The meaning of abbreviations is as follows: "hr." means hour(s),
"min." means minute(s), "sec." means second(s), "d." means day(s), "ml"
means milliliter(s), "cm" means centimeter(s), "mm" means millimeter(s),
"g" means gram(s), "N" means newton(s), "HEMA" means 2-hydroxyethyl
methacrylate, "IBOA" means isobornyl acrylate, "MMA" means methyl
methacrylate, "Mn" means number average molecular weight, "MW" means
weight average molecular weight, "cps" means centipoise.
EXAMPLE 1
Orthoester Composition A
200 ml of HEMA/IBOA copolymer (HEMA/IBOA = 37/63; M" _
1,700; MW = 2,450) 55% solution in aromatic hydrocarbon was placed into
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"'a "~'.~~"li'f~~''~as'k"~y~rq~~i~d with a magnetic stirrer, a thermocouple,
and a
downward condenser. The flask was flashed with nitrogen gas, and 100
ml of 2-ethoxy-1,3-dioxalane was added. The flask was placed into a
150°C oil bath for 1.5 hr. Then, 15 Torr vacuum was applied at
140°C in
the oil bath to remove all volatile components. After 1 hr., the flask was
filled with nitrogen, and 30 ml of dry butyl acetate was added to adjust
viscosity. The polymer solution was chilled down to room temperature
and dispensed into an airtight container. 1R spectrum of the mixture
showed no significant signal from hydroxyl groups in the 3,100-3,300 cm-'
region.
EXAMPLE 2
Orthoester Composition B
1 ,700 ml of HEMA/MMA/IBOA copolymer (HEMA/MMA/IBOA =
22/15/63; M" = 1,490; Mw = 2,330) 55% solution in aromatic hydrocarbon
was placed into a 2 liter flask equipped with a mechanical stirrer, a
thermocouple, and a downward condenser. The flask was flashed with
nitrogen gas, and 350 ml of 2-ethoxy-1,3-dioxalane was added. The flask
was placed into a 150 °C oil bath for 1 hr. Then, 15 Torr vacuum was
applied at 140 °C in the oil bath to remove all volatile components.
After
1 hr., the flask was filled with nitrogen, and 100 ml of dry ethyl acetate
was added to adjust viscosity. The polymer solution was chilled down to
room temperature and dispensed into an airtight container. 1R spectrum
of the mixture showed no significant signal from hydroxyl groups in the
3,100-3,300 cm's region.
EXAMPLE 3
Orthoester Composition C
400 ml of HEMA/IBOA copolymer (HEMA/IBOA = 37/63; M" _
1,700; Mw = 2,450) 55% solution in aromatic hydrocarbon was placed into
a 1 liter flask equipped with a magnetic stirrer, a thermocouple, and a
downward condenser. The flask was flashed with nitrogen gas, and 400
ml of triethyl orthoformate was added. The flask was placed into a 150-
170°C oil bath for 1.5 hr. Then, 15 Torr vacuum was applied at
70°C in
the oil bath to remove all volatile components. After 1 hr., the flask was
filled with nitrogen, and 30 ml of dry ethyl acetate was added to adjust
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'~isc'd'sify:" ~'h~e ~~b[~~t~r''s'olution was chilled down to room temperature
and dispensed into an airtight container. 1R spectrum of the mixture
showed no significant signal from hydroxyl groups in the 3,100-3,300 cm ~
region.
EXAMPLE 4
Three coating compositions were created. The first, Coating A,
contained neither unprotected nor orthoester-protected
HEMA/MMA/IBOA. The second, Coating B, contained protected
HEMA/MMAIIBOA (in the form of Orthoester Composition B). The third,
Coating C, contained unprotected HEMA/MMA/IBOA. To create the
coating compositions, the components in Table 2 were mixed. All three
coatings contained a spiroorthocarbonate component (3,9-dibutyl-3,9-
diethyl-1,5,7,11-tetraoxaspiro[5,5]undecane) as described in Experiment
2 of co-pending, co-owned application Serial No. 60/261,450, wherein 2-
ethyl-1,3-hexanediol replaces 2-butyl-2-ethyl-1,3-propanediol.
Table 2
DESCRIPTION Coating Coating Coating
A B C
H EMA/MMAIIBOA
0 p 21.7
22/15/63
Spiroorthocarbonate
Compound (from 16 12 11
1 1 9
Experiment 2 of Serial. . .
No.
60/261,450
Orthoester Composition
B
0 17.6 0
from Example 2
Propylene Glycol 1 2 0
63 19
Monomethylether Acetate. .
2% Dibutyl Tin Dilaurate
in
5.69 5.69 5.45
Ethyl Acetate
10% BYKR 306 in Xylene1.16 1.16 1.11
TOTAL 24.6 38.8 40.3
rmyemC~-iiwuiiieu uuneuiyipolysiloxane sUppllB° Dy tfyK-l:nemle
The components in Table 3 were mixed.
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Table 3
DESCRIPTION Coating Coating Coating
A B C
Desmodur Z 4470 BA 4.21 0 0
DesmodurR N 3300A 26.4 21.1 19.7
Propylene Glycol
Monomethylether 4.74 0 0
Acetate
TOTAL 35.4 21.1 19.7
muayanme uuner or isopnorone ansaayanme suppnea ay gayer ~:orp.
Zlsocyanate trimer of hexamethylene diisocyanate supplied by Bayer Corp.
The resultant mixture for each coating of Table 3 was added to the
resultant mixture for each coating of Table 2 and stirred. To these
mixtures was added Nacure~XP-221. The final volumes of the three
coating compositions are listed in Table 4.
Table 4
PART Coating Coating Coating
A B C
Table 1 Mixture24.6 38.8 40.3
Table 2 Mixture35.4 21.1 19.7
NacureR XP-221 0.65 0.65 0.62
TOTAL 60.7 60.6 60.6
iu ro sownon or aoaecymenzene sultomc acid In isopropanol; Klng Industries,
Norwalle, Conn.
The three coating compositions were tested for Gardner Holt
viscosity, cotton tack free time, BK3 time, and water spot rating.
Gardner-Holt viscosity was measured under ASTM test D1545.
In order to determine cotton tack free time, a coated panel is
allowed to dry for a set period of time (for example, 30 min.). A cotton ball
is dropped from a height of 2.5 cm onto the surface of the panel, and the
cotton ball is left on the surface for a set time interval (for example,
intervals of 30 min.). The panel is then inverted. These steps are
repeated until the cotton ball drops off the panel on inversion (that is, the
cotton tack free time).
The dry time of a coated layer of the composition was measured as
BK3 surface dry time under ASTM test D5895.
Water spot rating is a measure of how well the coating composition
is cross-linked early in the curing of the coating composition. Water spot
damage on the coating composition indicates that the cure is not
complete and further curing of the coating composition is needed before
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°tf'ie''cod'fi'ii~"'C'or'i~'b'~'s~tic~~i ''can be wet sanded, buffed,
or moved from the
spray booth. The water spot rating is determined as follows. Panels
coated with the test coating compositions were laid on a flat surface and
deionized water was applied with a pipette at 1 hr. timed intervals. A drop
of about 1.25 cm in diameter was placed on the panel and allowed to
evaporate. The spot on the panel was checked for deformation and
discoloration. The panel was wiped lightly with cheesecloth wetted with
deionized water followed by lightly wiping the panel dry with the cloth.
The panel was then rated on a scale of 1 to 10. A rating of 10 is best - no
evidence of spotting or distortion of discoloration; rating 9 - barely
detectable; rating 8 - slight ring; rating 7 - very slight discoloration or
slight distortion; rating 6 - slight loss of gloss or slight discoloration;
rating
- definite loss of gloss or discoloration; rating 4 - slight etching or
definite distortion; rating 3 - light lifting, bad etching, or discoloration;
rating 2 - definite lifting; and rating 1 - dissolving of the coating
composition.
Table 5 shows the cure improvement found in Coating B because
of the addition of the orthoester group (Orthoester Composition B)
compared with Coating A without substantially harming potlife. Coating C
versus Coating B is a comparison of the unprotected material (C) versus
protected material (B). Coating B has better potlife at higher solids (75%
versus 72% solids) with similar cure.
Table 5
TEST Coating A Coating Coating
B C
Solids 75 75 72
WT Solids 45 45 43.2
NCO/OH 1.40 1.03 1.03
Gardner-Holt 0 A A A
hr.
Gardner-Holt 1 C H H
hr.
Gardner-Holt 2 D I M
hr.
Cotton Tack Free ~$ 5 4
Time in hr.
BK3 in min. 621 170 156
Water Spot Rating 7 10 9
after 4 hr.
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EXAMPLE 5
For each of the coating compositions D-H, Portions 1, 2, and 3
were mixed together to form the coating composition as shown in Table 6.
Coatings G and H contained an amide acetal compound as described in
Example 4 of co-pending, co-ov~rned application Serial No. 60/509,885.
Each of the coating compositions was applied with a doctor blade over a
separate phosphated cold roll steel panel primed with a layer of
PowerCron° Primer supplied by PPG, Pittsburgh, Pa., to a dry
coating
thickness of 50,~m. Coating compositions D-F were air dried at ambient
temperature conditions, and a second set of panels was baked for 20 min.
at 60°C. Coating compositions G and H were baked for 20 min. at
60°C.
Table 6
Description Coating Coating Coatin Coating Coating
D E F G H
Portion 1
IBOA/HEMA Acrylic-
30 0 0 0 0
Un rotected
H drox I
Orthoester
Composition 0 26.36 39.51 4.0 4.0
C (from
Exam 1e 3
Amide Acetal
Compound (from
0 0 0 15.0 15.0
Example 4 of
Serial
No. 60/509,885
But I Acetate 11.94 11.11 14.72 0 0
Diisobut I Ketone0 0 0 2.41 1.42
Flow Additive 0.3 0.35 0.47 0.42 0.42
Catal st Solution1.5 5.32 7.18 1.51 1.51
'
Portion 2
Tolonate HDT" 10.74 10.74 10.74 0 0
Desmod _
u
S Z 4470
B 0 0 0 10.39 10.39
A
Desmodur~' XP 0 0 0 16.96 16.96
2410
Diisobut I Ketone0 0 0 2.05 2.05
Portion 3
25% Sulfonic
Acid' in
0 0.77 1.04 0 1.44
Iso ro anol
Acetic Acid 0 0 0 0.14 0
'20% BYK° 301 flow additive in propylene glycol monomethyl ether
acetate supplied
by BYK-Chemie
ZCoating compositions D-F: 1 % di butyl tin dilaurate in ethyl acetate
supplied by Elf
Atochem North America
3Coating compositions G-H: 10% di butyl tin dilaurate in ethyl acetate
supplied by Elf
Atochem North America
"Isocyanate trimer of hexamethylene diisocyanate supplied by Rhodia, Inc.
(Cranbury,
N.J.)
5lsocyanate trimer of isophorone diisocyanate supplied by Bayer Corp.
eisocyanate trimer of hexamethylene diisocyanate supplied by Bayer Corp.
'Aromatic sulfonic acid; Nacure° XP-221 in isopropanol supplied by King
Industries
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~'~i~v~tia~~i~~i~~' ~°b'Y~i~'ositions were tested for BK3 time, BK4
time,
cotton tack free time, water spot rating, swell ratio, Person Hardness,
Fischer Hardness, MEK solvent resistance, gel fraction, viscosity, time to
gel, and weight solids.
Cotton tack free time, BK3 time, and water spot rating tests were
performed as described in Example 5.
The dry time of a coated layer of the composition was also
measured as BK4 surface dry time under ASTM test D5895.
The swell ratio of a free film (removed from a sheet of TPO-
thermoplastic olefin) was determined by swelling the film in methylene
chloride. The free film was placed between two layers of aluminum foil
and using a LADD punch, a disc of about 3_5 mm in diameter was
punched out of the film and the foil was removed from the film. The
diameter of the unswollen film ("Do") was measured using a microscope
with a 10x magnification and a filar lens. Four drops of methylene
chloride were added to the film and the film was allowed to swell for a few
second and then a glass slide was placed over the film and the swollen
film diameter ("DS") was measured. The swell ratio was then calculated
as follows: Swell Ratio = (DS)2/(Do)2.
The change in film hardness (Person Hardness) of the coating was
measured with respect to time by using a Person hardness tester Model
No. 5854 (ASTM D4366), supplied by Byk-Mallinckrodt, Wallingford,
Conn. The number of oscillations (referred to as Person number) was
recorded.
Fischer Hardness was measured using a Fischerscope~ hardness
tester (the measurement is in N/mm2).
The MEK Solvent Resistance Test was performed by rubbing a
coated panel (100 times) with an MEK (methyl ethyl ketone) soaked cloth
using a rubbing machine, and excess MEK was wiped off. The panel was
then rated from 1-10. Rating of 10 means no visible damage to the
coating, 9 means 1 to 3 distinct scratches, 8 means 4 to 6 distinct
scratches, 7 means 7 to 10 distinct scratches, 6 means 10 to 15 distinct
scratches with slight pitting or slight loss of color, 5 means 15 to 20
distinct scratches with slight to moderate pitting or moderate loss of color,
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"4rrrV~a~~i~°~~Chat~f~~r~'sat~~itfi~'~o blend into one another, 3 means
only a few
undamaged areas between blended scratches, 2 means no visible signs
of undamaged paint, 1 means complete failure, that is, bare spots are
shown. The final rating was obtained by multiplying the number of rubs
by the rating.
Gel Fraction was measured according to the procedure set forth in
U.S. Patent No. 6,221,494 at column 8, line 56 to column 9, line 2, which
procedure is hereby incorporated by reference.
Viscosity was measured on an ICI cone & plate viscometer in
centipoises at 10,000 sec ~ shear rate and/or in seconds using a Zahn #2
cup viscometer.
Time to Gel is the time it takes for a liquid coating to gel.
The weight solids are measured using pre-weighed aluminum
dishes:
1 ) 2-4 ml of Aromatic 100 solvent from ExxonMobil
Chemical Company (Houston, Tex.) are placed in the
aluminum dish;
2) 0.2 - 0.4 g of the experimental material is weighed into
the dish containing the solvent;
3) the multi-component clear coating is allowed to sit for 60
min. at room temperature;
4) the sample is then placed in an oven at 110 +l- 5 °C for
60 min.;
5) the sample is removed from the oven, allowed to cool at
room temperature, and weighed;
6) the weight solids is calculated as:
Weight solids = Weight of sample in AI dish after oven heating x 100
Weight of initial experimental sample
The results of the tests are shown in Table 7.
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Table 7
Test Coatin Coating Coatin Coating Coatin
D E F G H
Weight Solids
55 --- --
Theoretical --- ---
Weight Solids
___ 53.6 55.4 83 85
Measured
ICI Viscosity 30 35 40 --- ---
(cps)
Time to Gel 157 min.> 5.5 > 6 hr. > 24 > 24
hr. hr. hr.
BK3 TIME (min.) 203 66.1 87.3 --- ---
BK4 TIME (min.) 484 212 441 --- ---
Cotton Free Tack
235 180 225
Time min. --- ---
APP - WET Good Good Good Good Good
APP/clarity -DRY Good Good Good Good Good
Water Spot Rating
7 8 8
after 4 hr. --- ---
Water Spot Rating
7 8 8
after 1 d. --- ---
Water Spot Rating
8 g g 10 10
60 C bake - Initial
Water Spot Rating
60 C Bake + 1 8 8.5 8 10 10
d.
at Room Tem erature
MEK Rub after
4 hr.
700 800 750
at Room Tem erature --- ---
MEK Rub after
1 d.
800 800 800
at Room Temperature --- ---
MEK Rub
750 800 800 650 700
60 C Bake - Initial
MEK Rub
60 C Bake + 1 800 800 800 800 750
d.
at Room Tem erature
MEK Rub after
30 d.
700 800 700 ---
at Room Tem erature ---
MEK Rub
60 C Bake + 30 700 800 700 800 750
d.
at Room Tem erature
Swell Ratio after
1 d
. 1,86 1.75 1.88 ---
at Room Tem erature ---
Swell Ratio after
7 d.
1.61 1.66 1.84
at Room Temperature --- ---
Swell Ratio after
30 d
. 1.63 1.67 1.82
at Room Tem erature --- ---
Swell Ratio
2.06 1.88 2.04 1.85 2.31
60 C Bake - Initial
Swell Ratio
60 C Bake + 1 1.75 1.74 1.86 1.81 2.18
d.
at Room Tem erature
Swell Ratio
60 C Bake + 7 1.68 1.67 1.82 2.1 2.15
d.
at Room Tem erature
Swell Ratio
60 C Bake + 30 1.63 1.67 1.82 2.1 2.16
d.
at Room Tem erature
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WO 2005/092934 PCT/US2005/008887
i .~y'~,i'~~~a~Cfi~i:;~~~
''aft''' ~~"d".',~
at Room Tem erature92.49 93.29 91.09 --- ---
Gel Fraction
60 C Bake + 30 94.29 93.8 92.27 92.37 91.79
d.
at Room Tem erature
Persoz Hardness
after
23 55 61 --- -
4 hr. at Room - -
Tem erature
Persoz Hardness
after
128 163 159 --- --
1 d. at Room Tem -
erature
Persoz Hardness
135 166 159 79 145
60 C Bake - Initial
Persoz Hardness
60 C Bake + 1 216 206 180 86 130
d.
at Room Tem erature
Fischer Hardness
after
33.6 62 57.5 --- ---
1 d. at Room Tem
erature
Fischer Hardness
after
106 79 89 --- ---
7 d. at Room Tem
erature
Fischer Hardness
after
30 d. at Room 118 122 114 --- ---
Temperature
Fischer Hardness
54.4 54 51 23 43.1
60 C Bake - Initial
Fischer Hardness
60 C Bake + 1 99 83 68 27 31.3
d.
at Room Tem erature
Fischer Hardness
60 C Bake + 7 162 145 81.6 49 59
d.
at Room Tem erature
Fischer Hardness
60 C Bake + 30 154 126 111 73 81
d.
at Room Tem erature
Zahn # 2 (in sec.)
-_- ___ ___ 21.06 20.19
Initial:
Zahn # 2-1 hr. --- --- --- 27.61 45.56
Zahn # 2-2 hr. --- --- --- 33.15 64.06
Zahn # 2-3 hr. --- --- --- 36.88 71.75
Zahn # 2-4 hr. --- --- --- 38.54 75.59
Zahn # 2-5 hr. --- --- --- 41.03 79.31
Zahn # 2-6 hr. --- --- --- 42.23 85.68
Comparing coatings E and F to coating D shows significant
advantages of using polymers with protected hydroxyl groups over the use
of more conventional acrylics with hydroxyl groups in coatings. Coatings
E and F have significantly improved time to gel and early cure, as
indicated by improved BK3 times and higher 4 hr. and 1 d. room
temperature hardness, over coating D.
-27-
CA 02557439 2006-08-24
WO 2005/092934 PCT/US2005/008887
~'tv'tin~~'~'~~h'~f 'H show that coatings using polymers with
protected hydroxyls can be made at very high solids (83-85%) and low
VOC (<2.1 pounds per gallon) while maintaining good cure and pot life
(>24 hr. in time to gel and up to 6 hr. for fihe viscosity to double).
_~8_
