U.S. patent application number 13/976803 was filed with the patent office on 2013-10-24 for radiation curable coating compositions for metal.
This patent application is currently assigned to AKZO NOBEL COATINGS INTERNATIONAL B.V.. The applicant listed for this patent is Gary Pierce Craun, Kenneth James Gardner, Patricia Miller. Invention is credited to Gary Pierce Craun, Kenneth James Gardner, Patricia Miller.
Application Number | 20130280544 13/976803 |
Document ID | / |
Family ID | 43706753 |
Filed Date | 2013-10-24 |
United States Patent
Application |
20130280544 |
Kind Code |
A1 |
Craun; Gary Pierce ; et
al. |
October 24, 2013 |
RADIATION CURABLE COATING COMPOSITIONS FOR METAL
Abstract
Various embodiments of radiation curable coating compositions
are provided. In one embodiment, a radiation curable coating
composition includes a (meth)acrylate functional compound and an
adhesion promoting (meth)acrylate compound. The radiation curable
coating composition can also include a (meth)acrylate functional
compound, a poly(meth)acrylate and a reactive diluent. The
(meth)acrylate functional compound can be made from the reaction of
a multifunctional isocyanate, a polyol and a hydroxyl functional
(meth)acrylate in the presence of a catalyst.
Inventors: |
Craun; Gary Pierce; (Berea,
OH) ; Gardner; Kenneth James; (Independence, OH)
; Miller; Patricia; (Cleveland, OH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Craun; Gary Pierce
Gardner; Kenneth James
Miller; Patricia |
Berea
Independence
Cleveland |
OH
OH
OH |
US
US
US |
|
|
Assignee: |
AKZO NOBEL COATINGS INTERNATIONAL
B.V.
Arnhem
NL
|
Family ID: |
43706753 |
Appl. No.: |
13/976803 |
Filed: |
December 23, 2011 |
PCT Filed: |
December 23, 2011 |
PCT NO: |
PCT/EP2011/073931 |
371 Date: |
June 27, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61427582 |
Dec 28, 2010 |
|
|
|
Current U.S.
Class: |
428/461 ;
524/507 |
Current CPC
Class: |
C09D 133/04 20130101;
C08F 222/1006 20130101; C08F 230/02 20130101; C08G 18/672 20130101;
C09D 4/00 20130101; Y10T 428/31692 20150401; C08F 220/18 20130101;
Y10T 428/31699 20150401; C09D 133/14 20130101; C08G 18/48 20130101;
C08G 18/672 20130101; C09D 175/16 20130101; C08G 2390/40
20130101 |
Class at
Publication: |
428/461 ;
524/507 |
International
Class: |
C09D 133/04 20060101
C09D133/04 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 10, 2011 |
EP |
11154036.5 |
Claims
1. A radiation curable coating composition comprising a
(meth)acrylate functional compound, a poly(meth)acrylate and a
reactive diluent.
2. The coating composition of claim 1, wherein the
poly(meth)acrylate is present in an amount up to about 20 wt % of
the coating composition.
3. The coating composition of claim 1, wherein the
poly(meth)acrylate comprises tricyclodecyl dimethanol diacrylate,
dipropylene glycol diacrylate, or a combination thereof.
4. The coating composition of claim 1, wherein the reactive diluent
is present in an amount from about 20 to about 95 wt % of the
coating composition.
5. The coating composition of claim 1, wherein the reactive diluent
comprises a mono(meth)acrylate.
6. The coating composition of claim 1, wherein the (meth)acrylate
functional compound is made from the reaction of a multifunctional
isocyanate, a polyol and a hydroxyl functional (meth)acrylate in
the presence of a catalyst.
7. The coating composition of claim 6, wherein the molar ratio of
multifunctional isocyanate/polyol/hydroxyl functional
(meth)acrylate is about 1/0.1-2/0.2-5.
8. The coating composition of claim 6, wherein the hydroxyl
functional (meth)acrylate comprises a hydroxyl monomer, 4-hydroxy
butyl (meth)acrylate, butane diol mono-(meth)acrylate, hydroxy
propyl (meth)acrylate, hydroxy ethyl (meth)acrylate, an extended
hydroxyl (meth)acrylate, polycaprolactone (meth)acrylate, or a
combination thereof.
9. The coating composition of claim 6, wherein the multifunctional
isocyanate comprises an isocyanate, a di-isocyanate, a
poly-isocyanate, an aliphatic isocyanate, an aromatic isocyanate,
di-hexamethylene, poly-hexamethylene, hexane diisocyanate,
isophorane, MDI, or a combination thereof.
10. The coating composition of claim 6, wherein the polyol
comprises a polyester, a diol, an alcohol, a polycarbonate,
polypropylene glycol, polyethylene glycol, polytetramethylene
oxide, or a combination thereof.
11. The coating composition of claim 6, wherein the catalyst
comprises a tin catalyst, dibutyl tin di-laurate, dibutyl tin
oxide, a zirconium catalyst, zirconium propionate, a bismuth
catalyst, bismuth neodecanoate, a tertiary amine, triethylene
diamine, or a combination thereof.
12. The coating composition of claim 1, further comprising at least
one multifunctional (meth)acrylate.
13. A packaging comprising: a metal substrate; and the radiation
curable coating composition of claim 1.
14. The packaging of claim 13, wherein the radiation curable
coating composition directly contacts the metal substrate without a
prime coat.
15. A method of coating a packaging comprising: a) preparing the
radiation curable coating composition of claim 1; and b) applying
the radiation curable coating composition to the packaging.
16. The method of claim 15, wherein the packaging is a metal
substrate.
Description
BACKGROUND OF THE INVENTION
[0001] The present disclosure relates to radiation curable coating
compositions that can provide useful coatings and coated surfaces
for packaging materials such as metal cans. Currently available
radiation curable coatings such as those that cure through
ultra-violet ("UV") radiation or electron beam ("EB") radiation
have a tendency to be inflexible cured coatings that are prone to
higher levels of shrinkage. Consequently, coatings utilizing
chemistry for such curing have been heretofore recognized by those
skilled in the art to be inadequate in terms of direct to metal
adhesion, formability, and retort resistance as well as limited in
application in terms of adhesion and extensibility within the
flexible packaging industry. Attempts to address these concerns can
lead to disadvantages of relying on either; (1) processes which
require high temperature flash before initiating the radiation
cure, as in polyurethane dispersions ("PUD's"), (2) cationic
chemistry, which suffers the disadvantage of humidity inhibition of
cure, photoinitiator, and currently, high cost due to supply
issues, (3) application of high temperature bake, post radiation
cure, and/or application of prime coat, to confer adhesion, and/or
(4) reliance on conventional solvent and waterborne thermoset
chemistries which regress to the disadvantages of releasing
volatile organic compounds ("VOCs"), BADGE/NOGE moieties. Thus, any
composition which addresses one or more of these issues, while also
dispensing with one or more of these disadvantages in radiation
cure coatings chemistry would provide one or more benefits for use
while positively impacting safety, health, and environmental
concerns.
[0002] While adhesion promoters are known in the art, it is
surprising that higher levels of these compounds than normally used
in supplier literature or other published information offer such a
significant improvement in adhesion and do not cause severe
problems with blush resistance of the cured coating. Higher levels
are especially useful on "cleaned only" metal substrates without
pretreatment and chrome free substrates.
SUMMARY OF THE INVENTION
[0003] The present invention includes radiation curable coating
compositions comprising a (meth)acrylate functional compound and an
adhesion promoting (meth)acrylate compound as well as radiation
curable coating compositions comprising a (meth)acrylate functional
compound, a poly(meth)acrylate and a reactive diluent. The present
invention also includes packaging comprising: a metal substrate;
and a radiation curable coating composition disposed on the
substrate.
[0004] Further, the present invention includes methods of coating a
packaging comprising: a) preparing a radiation curable coating
composition as described herein; and b) applying the coating
composition to the packaging. The radiation curable coatings of the
present invention have been found to be hard, flexible and exhibit
good adhesion to metal substrates. The coated films of the present
invention can withstand retort conditions with minimal blush and
minimal loss of adhesion.
DETAILED DESCRIPTION OF THE INVENTION
[0005] The present invention includes radiation curable coating
compositions comprising a (meth)acrylate functional compound and an
adhesion promoting (meth)acrylate compound as well as radiation
curable coating compositions comprising a (meth)acrylate functional
compound, a poly(meth)acrylate and a reactive diluent. The
(meth)acrylate functional compound can be made for non-limiting
example from the reaction of a multifunctional isocyanate, a polyol
and a hydroxyl functional (meth)acrylate in the presence of a
catalyst. The (meth)acrylate functional compound and the adhesion
promoting (meth)acrylate compound may each be a monomer, an
oligomer, or combination thereof, and references to a monomer are
understood to include an oligomer and vice-versa.
[0006] In some embodiments, the (meth)acrylate functional compound
is present in an amount up to about 50 wt % of the coating
composition. The (meth)acrylate functional compounds can be made
from various materials known in the art, such as and without
limitation, a (meth)acrylate functional polyester, a (meth)acrylate
functional polyacrylate, a (meth)acrylate functional polyether, a
(meth)acrylate functional polycarbonate, an oil polyol ether, a
(meth)acrylate functional urethane, a (meth)acrylate functional
compound of WO 2008/151286 (the contents of which are incorporated
herein by reference), or a combination thereof. One possible
(meth)acrylate functional compound is a urethane, made readily but
not exclusively from the reaction of a multifunctional isocyanate,
a polyol and a hydroxyl functional (meth)acrylate in the presence
of a catalyst.
[0007] The adhesion promoting (meth)acrylate compound may be for
non-limiting example a phosphate (meth)acrylic-functional monomer,
a carboxylate (meth)acrylic-functional monomer, a phosphate
(meth)acrylic-functional oligomer, a carboxylate
(meth)acrylic-functional oligomer, or a combination thereof. In
some embodiments, the phosphate (meth)acrylic-functional monomer
may include phosphate esters or hydroxyl functional esters of
methacrylic acid. The carboxylate (meth)acrylic-functional
monomer/oligomer may include without limitation carboxylic acid
functional esters, carboxylic acid functional ethers and
combinations thereof. In certain embodiments of the invention, the
phosphate (meth)acrylic-functional monomer/oligomer may be present
in an amount up to about 12 wt % of the coating composition. The
carboxylate (meth)acrylic-functional monomer/oligomer may be
present in an amount from about 0.5 to about 50 wt % of the coating
composition.
[0008] The adhesion promoting (meth)acrylate compound may be
present in an amount up to about 65 wt % of the total coating
composition film forming components.
[0009] In some embodiments of the invention, the poly(meth)acrylate
is present in an amount up to about 25 wt % of the coating
composition or from about 5 to about 15 wt %. The
poly(meth)acrylate may include without limitation tricyclodecyl
dimethanol diacrylate, dipropylene glycol diacrylate, and the like,
as well as combinations thereof.
[0010] The reactive diluent can be present in an amount up to about
95 wt % of the coating composition or from about 20 to about 60 wt
%. The reactive diluent may include without limitation a
mono(meth)acrylate.
[0011] Multifunctional isocyanates for use in the present invention
include but are not limited to an isocyanate, a di-isocyanate, a
poly-isocyanate, an aliphatic isocyanate, an aromatic isocyanate,
di-hexamethylene, poly-hexamethylene, hexane diisocyanate,
isophorane, MDI, and combinations thereof.
[0012] Polyols for use in the present invention include but are not
limited to polyesters, diols, alcohols, polycarbonates,
polypropylene glycol, polyethylene glycol, polytetramethylene
oxide, and combinations thereof. In some embodiments of the
invention, the polyol has a molecular weight of about 100 to about
10,000, or about 500 to about 5000.
[0013] Suitable hydroxyl functional (meth)acrylates include but are
not limited to a hydroxyl monomer, 4-hydroxy butyl (meth)acrylate,
butane diol mono-(meth)acrylate, hydroxy propyl (meth)acrylate,
hydroxy ethyl (meth)acrylate, an extended hydroxyl (meth)acrylate,
polycaprolactone (meth)acrylate, and combinations thereof. The
amount of the hydroxyl functional (meth)acrylate can range from
about 5% to about 95% by weight based on the weight of the
(meth)acrylate functional compound, and in other examples from
about 25% to about 75% by weight based on the weight of the
(meth)acrylate functional compound.
[0014] In some embodiments of the invention, the molar ratio of
multifunctional isocyanate/polyol/hydroxyl functional
(meth)acrylate is about 1/0.1-2/0.2-5, about 1/0.25-0.75/0.5-2.5,
or about 1/0.5/2. On a weight basis, the ratio can be about 1 to
about 75% of the multifunctional isocyanate to up to about 90% of
the polyol to about 1 to about 99% of the hydroxyl functional
(meth)acrylate. In some embodiments, there is a slight excess of
hydroxyl functionality over isocyanate functionality which allows
the reaction to proceed to at least 99% conversion of the
multifunctional isocyanate.
[0015] Additional hydroxyl functional materials can be included
with the hydroxyl functional (meth)acrylate. Additional hydroxy
functional materials can include but are not limited to alcohols,
diols, polyols, polyesters, polyethers (such as for non-limiting
example, benzyl alcohol, trimethylol propane, polypropylene glycol,
hexane diol), and combinations thereof.
[0016] The catalyst can be a catalyst suitable for polymerization
such as without limitation a tin catalyst such as dibutyl tin
di-laurate or dibutyl tin oxide, a zirconium catalyst such as
zirconium propionate, a bismuth catalyst such as bismuth
neodecanoate, a tertiary amine catalyst such as triethylene
diamine, or a combination thereof. The amount of the catalyst can
range from about 1 ppm to about 10,000 ppm, from about 10 ppm to
about 1,000 ppm, or from about 20 ppm to about 200 ppm. It is
generally convenient to employ the catalyst in the form of a
solution in an organic solvent. Examples of suitable solvents
include without limitation aromatic hydrocarbon solvents,
cycloaliphatic polar solvents (such as cycloaliphatic ketones
including cyclohexanone), polar aliphatic solvents (such as
alkoxyalkanols including 2-methoxyethanol), the diol starting
material, and combinations thereof.
[0017] An air atmosphere and an effective inhibitor such as for
example methoxy hydroquinone, hydroquinone, di-tert butyl
hydroquinone, butylated hydroxyl toluene, phenothiazine, or a
combination thereof can be used to prevent free radical
polymerization of the hydroxyl functional (meth)acrylate
monomer/oligomer. The inhibitor may be present in an amount of
about 10 to about 10,000 ppm. The reaction of the multifunctional
isocyanate, the polyol and the hydroxyl functional (meth)acrylate
can be carried out at a temperature that ranges from about ambient
temperature to about 70.degree. C. or about 110.degree. C., an in
other examples from about 90.degree. C. to about 100.degree. C.
Typically, at least 90% conversion, and in some embodiments at
least 99% conversion of the isocyanate groups can be obtained in
about 1 hour at 90.degree. C. Additionally, a diluent may be added
during the reaction to reduce viscosity, such as for non-limiting
example a free radical reactive species such as a (meth)acrylate, a
methyl(meth)acrylate, isobornyl (meth)acrylate, t-butyl cyclohexyl
(meth)acrylate, tricyclodecyl dimethanol di(meth)acrylate, or a
combination thereof. The diluent may be present in an amount up to
about 75% or more of the total batch weight.
[0018] Various embodiments of the present invention provide
radiation cured coating compositions that are essentially free of
BADGE and NOGE even when cured with low energy curing, such as
electron beam curing. The various radiation cured coating
compositions described herein have improved flexibility and are,
for example, more flexible than coatings with other (meth)acrylate
coatings. The coating compositions of the present invention can
also provide retort resistance for rigid packaging applications
according to the most common retort tests know for rigid packaging
applications. The curable coating compositions of the present
invention can be used without the need for a prime coat so as to be
in direct contact to metal substrates. The coating compositions can
be applied to substrates in any manner known to those skilled in
the art.
[0019] The following examples are given for the purpose of
illustrating the described systems and processes and should not be
construed as limitations on the scope or spirit thereof.
EXAMPLES
Example 1
Preparation of a Urethane Oligomer
[0020] In a 1 liter flask, 99 g of Bayer N-3900 was mixed with 200
g of polypropylene glycol 2000, 153 g of isobornyl acrylate, 57.6 g
of 4-hydroxy butyl acrylate and 0.15 g of phenothiazine. The
mixture was placed in a 90 .degree. C. hot water bath under an air
blanket and stirred. To the resulting mixture, 0.5 ml of a 10%
solution of di-butyl tin di-laurate in methyl ethyl ketone was
added. The resulting mixture was held for 2 hours then cooled.
Example 2
[0021] The following ingredients were added under agitation while a
mixing operation was done under medium speed agitation. The
finished coating was drawn down over a metal substrate and cured
under electron beam at a minimum setting of 3 megarads per 90
kilovolts.
TABLE-US-00001 Weight Percent of Formulation A B C D E F G H I J
Oligomer 0 4 40.45 0 40 25.33 54 53.7 53.4 52.2 Laromer TBCH 57 55
34.4 34.4 21.7 44.37 36 35.8 35.6 34.8 SR 833 - ADCP 16 15 9.11
9.11 21.8 10.8 0 0.5 0.5 0.5 Generad 40 4 4 2.5 2.5 1.7 3.1 0 0 0.5
0.5 Photomer 4046 9 9 5.3 45.75 3.6 5.8 0 0 0 2 Lubricant 14 13
8.24 8.24 11.2 10.6 10 10 10 10 Total 100 100 100 100 100 100 100
100 100 100 adhesion 5 5 5 5 5 5 0 0 0 3 direct to metal * Erichsen
Cup 4 4 3 5 3 3 0 0 0 3 Formation * Retort Blush 3 3 3 5 3 3 0 0 0
2 60 mins @ 262 F.** Pencil Hardness 2 H 2 H 2 H 3 H 2 H 2 H N/A
N/A N/A H * Rating 0-5, 5 = excellent **Blush ratings: 5 - no
blush, 4 - very slight, 3 - slight, 2 - blushed, 1 and 0 -
failure
* * * * *