U.S. patent application number 14/973265 was filed with the patent office on 2016-06-16 for novel compositions and methods to produce triazine-arylhydroxy-aldehyde condensates with improved solubility.
The applicant listed for this patent is Hexion Inc.. Invention is credited to Vinay MALHOTRA, Ganapathy S. VISWANATHAN.
Application Number | 20160168306 14/973265 |
Document ID | / |
Family ID | 45594580 |
Filed Date | 2016-06-16 |
United States Patent
Application |
20160168306 |
Kind Code |
A1 |
VISWANATHAN; Ganapathy S. ;
et al. |
June 16, 2016 |
NOVEL COMPOSITIONS AND METHODS TO PRODUCE
TRIAZINE-ARYLHYDROXY-ALDEHYDE CONDENSATES WITH IMPROVED
SOLUBILITY
Abstract
Compositions and methods for forming condensates and resin
compositions are provided. In one embodiment, a condensate is
formed from a reaction mixture including a triazine monomer, an
arylhydroxy monomer, an aldehyde monomer and an acid catalyst
having a pKa value of greater than 3.8. The condensates contain up
to 28 wt. % of nitrogen and have a melt viscosity of 3,000 cps or
less at 175.degree. C. The condensates may have a solubility of at
least 80 wt. % solids dissolved in an organic solvent for 120 hours
or greater. Also disclosed are methods for the manufacture of the
condensate as well as the condensate's use in fire-retardant epoxy
resin compositions suitable for the manufacture of laminates for
electronic applications. There is also disclosed a glycidylated
triazine-arylhydroxy-aldehyde condensate of this invention.
Inventors: |
VISWANATHAN; Ganapathy S.;
(Louisville, KY) ; MALHOTRA; Vinay; (Louisville,
KY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Hexion Inc. |
Columbus |
OH |
US |
|
|
Family ID: |
45594580 |
Appl. No.: |
14/973265 |
Filed: |
December 17, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12858096 |
Aug 17, 2010 |
9249251 |
|
|
14973265 |
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Current U.S.
Class: |
523/456 ;
524/352; 528/144 |
Current CPC
Class: |
C08K 5/05 20130101; C08L
63/04 20130101; C08L 63/00 20130101; C08G 14/10 20130101; C08G
59/623 20130101; C08L 61/34 20130101; C08L 61/34 20130101; C08G
59/68 20130101 |
International
Class: |
C08G 14/10 20060101
C08G014/10; C08L 63/00 20060101 C08L063/00; C08K 5/05 20060101
C08K005/05 |
Claims
1. A condensation product of a reaction mixture, comprising: a
triazine monomer; an arylhydroxy monomer selected from the group
consisting of phenol, xylenols, bis-phenols, alkylated bisphenols,
alkoxyphenols, dihydroxy benzene, naphthols, biphenols, alkylated
biphenols, trisphenols, and combinations thereof; an aldehyde
monomer; an acid catalyst having a pKa value range from 4 to 6,
wherein the acid catalyst comprises an organic acid, wherein the
condensation product comprises greater than 10 wt. % to about 28
wt. % of nitrogen and a melt viscosity from about 1100 cps to less
than 3,000 cps at 175.degree. C.
2. The condensation product of claim 1, wherein the organic acid is
selected from the group consisting of a monocarboxylic acid, a
dicarboxylic acid, and combinations thereof.
3. The condensation product of claim 2, wherein the organic acid is
selected from the group consisting of acetic acid, adipic acid,
ascorbic acid, benzoic acid, cinnamic acid, adipamic acid,
o-aminobenzoic acid, p-aminobenzoic acid, anisic acid,
anisylpropionic acid, barbituric acid, butyric acid, isobutyric
acid, caproic acid, isocapropic acid, chlorobutyric acid,
chlorocinnamic acid, chlorophenylacetic acid,
(chlorophenyl)propionic acid, trans-cinnamic acid, trans-crotonic
acid, dihydroxybenzoic acid (3,4 and 3,5), ethylbenzoic acid,
ethylphenylacetic acid, trans-furmaric acid, gallic acid,
glutaramic acid, heptanoic acid, hexahydrobenzoic acid, hexanoic
acid, m-hydroxybenzoic acid, p-hydroxybenzoic acid, hydroxybutyric
acid, mesitylenic acid, naphthoic acid, o-nitrophenylacetic acid,
nonanic acid, octanoic acid, phenylacetic acid, propionic acid,
iso-propylbenzoic acid, pyridinecarboxylic acid, suberic acid,
toluic acid (meta and para), trimethylacetic acid, valeric acid,
vinylacetic acid, succinic acid, glutaric acid, methylsuccinic
acid, and combinations thereof.
4. The condensation product of claim 1, wherein the reaction
mixture comprises: the triazine monomer; from about 3 to about 30
moles of the arylhydroxy monomer for each mole of the triazine
monomer; from about 1 to about 6 moles of the aldehyde monomer for
each mole of the triazine monomer; and the acid catalyst having a
pKa value range from 4 to 6, wherein the acid catalyst comprises
from greater than 0.1 wt. % to less than 1 wt. % based on the
weight of the arylhydroxy monomer.
5. The condensation product of claim 1, wherein the condensation
product maintains a Gardner number of less than 3 for 150 days or
greater.
6. The condensation product of claim 1, wherein the condensation
product comprises a melt viscosity from about 1100 cps to about
1700 cps at 175.degree. C.
7. The condensation product of claim 1, wherein the triazine
monomer comprises a structure having the formula: ##STR00008##
wherein R.sub.1 and R.sub.2 are each independently a hydrogen atom
or a functional group selected from the group consisting of an
amino group, an alkyl group having 1 to 4 carbon atoms, phenyl
group, a vinyl group, and combinations thereof.
8. The condensation product of claim 1, wherein the triazine
monomer and the aldehyde monomer comprise an aldehyde modified
triazine monomer.
9. The condensation product of claim 1, wherein the condensation
product comprises a solubility from about 33% to at least about 80
wt. % solids dissolved for 120 hours or greater in one or more
organic solvents having one or more functionalities selected from
the group consisting of an ether functionality, a ketone
functionality, an alcohol functionality, an ester functionality,
and combinations thereof.
10. The condensation product of claim 1, wherein the reaction
mixture further comprises a stabilizer selected from the group
consisting of cresol, N-methyl pyrrolidone, hydroquinone,
triethylcitrate, butyrolactone, glycerol, and combinations
thereof.
11. A flame-retardant epoxy resin composition, comprising: an epoxy
resin; and a condensation product of a reaction mixture comprising:
a triazine monomer; an arylhydroxy monomer; an aldehyde monomer; an
acid catalyst having a pKa value range from 4 to 6, wherein the
acid catalyst comprises an organic acid; and a stabilizer of a
non-reactive diluent selected from the group consisting of esters,
hydroxyaryl moieties, dihydroxyaryl moieties, amides, alcohols,
ketones, and combinations thereof, wherein the condensation product
comprises greater than 10 wt. % to about 28 wt. % of nitrogen and a
melt viscosity from about 1100 cps to less than 3,000 cps at
175.degree. C.
12. The epoxy resin composition of claim 11, wherein the epoxy
resin composition is free of a separate amine catalyst or a
phosphorous containing catalyst.
13. The epoxy resin composition of claim 11, further comprising a
phenolic-formaldehyde novolac curing agent selected from the group
consisting of phenol novolac, cresol novolac, naphthol novolac,
bisphenol A novolac, phenol-glyoxal condensate, and combinations
thereof and co-polymers thereof.
14. The epoxy resin composition of claim 11, wherein the organic
acid is selected from the group consisting of a monocarboxylic
acid, a dicarboxylic acid, and combinations thereof.
15. The epoxy resin composition of claim 14, wherein the organic
acid is selected from the group consisting of acetic acid, adipic
acid, ascorbic acid, benzoic acid, cinnamic acid, adipamic acid,
o-aminobenzoic acid, p-aminobenzoic acid, anisic acid,
anisylpropionic acid, barbituric acid, butyric acid, isobutyric
acid, caproic acid, isocapropic acid, chlorobutyric acid,
chlorocinnamic acid, chlorophenylacetic acid,
(chlorophenyl)propionic acid, trans-cinnamic acid, trans-crotonic
acid, dihydroxybenzoic acid (3,4 and 3,5), ethylbenzoic acid,
ethylphenylacetic acid, trans-furmaric acid, gallic acid,
glutaramic acid, heptanoic acid, hexahydrobenzoic acid, hexanoic
acid, m-hydroxybenzoic acid, p-hydroxybenzoic acid, hydroxybutyric
acid, mesitylenic acid, naphthoic acid, o-nitrophenylacetic acid,
nonanic acid, octanoic acid, phenylacetic acid, propionic acid,
iso-propylbenzoic acid, pyridinecarboxylic acid, suberic acid,
toluic acid (meta and para), trimethylacetic acid, valeric acid,
vinylacetic acid, succinic acid, glutaric acid, methylsuccinic
acid, and combinations thereof.
16. The epoxy resin composition of claim 11, wherein the reaction
mixture comprises: the triazine monomer; from about 3 to about 30
moles of the arylhydroxy monomer for each mole of the triazine
monomer; from about 1 to about 6 moles of the aldehyde monomer for
each mole of the triazine monomer; and the acid catalyst having a
pKa value range from 4 to 6, wherein the acid catalyst comprises
from greater than 0.1 wt. % to less than 1 wt. % based on the
weight of the arylhydroxy monomer.
17. The epoxy resin composition of claim 11, wherein the triazine
monomer comprises a structure having the formula: ##STR00009##
wherein R.sub.1 and R.sub.2 are each independently a hydrogen atom
or a functional group selected from the group consisting of an
amino group, an alkyl group having 1 to 4 carbon atoms, phenyl
group, a vinyl group, and combinations thereof.
18. The epoxy resin composition of claim 11, wherein the reaction
mixture further comprises a stabilizer selected from the group
consisting of cresol, N-methyl pyrrolidone, hydroquinone,
triethylcitrate, butyrolactone, glycerol, and combinations
thereof.
19. The epoxy resin composition of claim 11, wherein the
condensation product comprises a solubility from about 33% to at
least about 80 wt. % solids dissolved for 120 hours or greater in
one or more organic solvents having one or more functionalities
selected from the group consisting of an ether functionality, a
ketone functionality, an alcohol functionality, an ester
functionality, and combinations thereof.
20. A method for the preparation of a condensate product,
comprising: charging to a reaction vessel to form a reaction
mixture: a triazine monomer; from about 3 to about 30 moles of an
arylhydroxy monomer for each mole of triazine monomer, wherein the
arylhydroxy monomer is selected from the group consisting of
phenol, xylenols, bis-phenols, alkylated bisphenols, alkoxyphenols,
dihydroxy benzene, naphthols, biphenols, alkylated biphenols,
trisphenols, and combinations thereof; from about 1 to about 6
moles of an aldehyde monomer for each mole of triazine monomer; and
an acid catalyst having a pKa from greater than 4 to 6; and heating
the reaction mixture to a temperature of about 120.degree. C. to
about 165.degree. C. and substantially completing reaction of
arylhydroxy monomer in the reaction mixture, wherein the
condensation product comprises greater than 10 wt. % to about 28
wt. % of nitrogen and a melt viscosity from about 1100 cps to less
than 3,000 cps at 175.degree. C.
21. The method of claim 20, wherein the triazine monomer and the
aldehyde monomer comprise an aldehyde modified triazine
monomer.
22. The method of claim 21, wherein the aldehyde modified triazine
monomer comprises hexamethoxymethylmelamine, the arylhydroxy
monomer is selected from the group consisting of phenol, cresols,
xylenols, bisphenols, and combinations thereof, and the acid
catalyst comprises the arylhydroxy monomer.
23. The method of claim 20, further comprising charging a
stabilizer selected from the group consisting of cresol, N-methyl
pyrrolidone, hydroquinone, triethylcitrate, butyrolactone,
glycerol, and combinations thereof, or one or more organic solvents
having one or more functionalities selected from the group
consisting of an ether functionality, a ketone functionality, an
alcohol functionality, an ester functionality, and combinations
thereof, or a combination thereof.
Description
RELATED APPLICATION DATA
[0001] This application is a continuation application of co-pending
U.S. patent application Ser. No. 12/858,096, filed Aug. 17, 2010,
of which the entire content of the application is hereby
incorporated by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to compositions for use with
epoxy and other resins, to methods for their preparation, and
processes for using the same. In particular, the present invention
relates to triazine-arylhydroxy-aldehyde condensates having
improved solubility in solvents that are formed using an acid
catalyst having a pKa value of greater than 3.8.
BACKGROUND OF THE INVENTION
[0003] Epoxy resins have excellent moisture, solvent, chemical and
heat resistance properties, good adhesion, and superior mechanical
and electrical properties, which make epoxy resins suitable for use
in constructing and packaging electronic products. In many cases,
flame retardant materials are included in the epoxy resin
compositions for use in electronic applications and/or electronic
components that require high flame retardancy.
[0004] In one approach, the flammability of the epoxy resin can be
reduced by physically blending a flame-retardant additive with the
epoxy resin. Some examples of such additive-type flame retardants
include antimony trioxide, aluminum trihydroxide, elemental
phosphorous, and inorganic phosphorous compounds. Unfortunately,
such additive-type flame retardants may be toxic. Additionally,
such additive-type flame retardants may be difficult to integrate
with the epoxy compositions, thereby, necessitating a high initial
loading of the additive-type flame retardants that adversely
influences the electrical or mechanical properties of the epoxy
resin.
[0005] One commonly used flame-retardant in epoxy compositions for
printed wiring boards (PWB) in electronic equipment is a
halogenated aromatic flame-retardant, such as a brominated aromatic
flame-retardant. The brominated aromatic flame-retardant, for
example, tetrabromobisphenol A (TBBPA) based compounds, chemically
bond with the polymer chain. Unfortunately, such halogenated
aromatic flame-retardant may emit corrosive halides and toxic
compounds during a fire. Additionally, there has been an increased
global interest in environmental protection leading to a higher
demand for halogen-free flame-retardants (HFFR) in the epoxy
formulations for PWB.
[0006] Alternatively, phosphorous or nitrogen containing epoxies
and/or epoxy curatives as flame retardants have been considered for
improving flame retardancy. Unfortunately, relatively large
quantities of phosphorous-based compounds are needed to provide for
sufficient flame-retardancy, which quantities have been observed to
greatly reduce heat and moisture resistance of the epoxy
resins.
[0007] Nitrogen-based flame retardants are considered advantageous
as they are observed to have a low toxicity, are physically stable,
and in case of fire, have an absence of toxic and corrosive
emissions with a low evolution of smoke. More recently,
triazine-phenol-aldehyde (TPA) condensates have been described as
flame retardant additives for epoxy resins. TPA condensates with
high nitrogen content are also effective curing agents for epoxy
resins leading to high efficiency in flame retardancy without
compromising the mechanical and physical properties of the
polymer.
[0008] However, one difficulty with TPA condensates is that the
current condensate compositions exhibit higher viscosity and lower
nitrogen content than desired. For example, existing processes
typically produce an atomic nitrogen content of only about 1 to 10
wt. %. TPA condensates have also been observed to exhibit
instability at higher temperatures that limit the large scale
manufacturing of such condensates.
[0009] Conventional processes for forming TPA condensates have been
found to be disadvantageous as the resulting condensates exhibited
an undesirable increase in viscosity and also exhibited a decreased
solubility in commons solvents, such as methyl ethyl ketone (MEK)
and acetone, typically used in epoxy formulations. The solubility
of the TPA condensates in such solvents is important since residues
or insolubles in the epoxy resins may result in less than desirable
coating of substrates and degrade the quality of the laminates made
from the epoxy resins.
[0010] Other conventional TPA condensate formation processes
prepare compounds with large amounts of methanol as a reactant,
which present special challenges on commercial scale productions
including handling, waste, and expense.
[0011] Therefore, there is a need for forming flame-retardant
condensates, with improved viscosity and improved solubility that
are effective curing agents, provide fire-retardant properties to
epoxy compositions and which may be manufactured on a commercial
scale.
SUMMARY OF THE INVENTION
[0012] Embodiments of the invention are directed to condensates,
methods for making the condensates, and application of the
condensates in epoxy resins, prepregs of a porous substrate, and
laminates. In one aspect, the present invention provides for a
condensate product formed from a reaction mixture of a triazine
monomer, an arylhydroxy monomer, an aldehyde monomer, and an acid
catalyst having a pKa value range from greater than 3.8 to about
11, wherein the condensation product comprises up to about 28 wt. %
of nitrogen, a melt viscosity of less than 3,000 cps at 175.degree.
C., and a solubility of up to at least about 80 wt. % solids
dissolved for 120 hours or greater in one or more organic solvents
having one or more functionalities selected from the group
consisting of an ether functionality, a ketone functionality, an
alcohol functionality, an ester functionality, and combinations
thereof. The condensates described herein may be substantially free
of water and may have about 2 wt. % or less of free arylhydroxy
monomer. The triazine monomer and the aldehyde monomer may comprise
an aldehyde modified triazine monomer.
[0013] In another aspect, the present invention provides for a
flame-retardant epoxy resin composition including an epoxy resin
and a triazine-arylhydroxy-aldehyde condensate of a reaction
mixture including a triazine monomer, an arylhydroxy monomer, an
aldehyde monomer, and an acid catalyst having a pKa value range
from greater than 3.8 to about 11, wherein the
triazine-phenol-aldehyde condensate comprises up to about 28 wt. %
of nitrogen, a melt viscosity of less than 3,000 cps at 175.degree.
C., and a solubility of up to at least about 80 wt. % solids
dissolved for 120 hours or greater in one or more organic solvents
having one or more functionalities selected from the group
consisting of an ether functionality, a ketone functionality, an
alcohol functionality, an ester functionality, and combinations
thereof.
[0014] In another aspect, the present invention provides a method
for the preparation of a condensate product including charging to a
reaction vessel to form a reaction mixture a triazine monomer, from
about 3 to about 30 moles of an arylhydroxy monomer for each mole
of triazine monomer, from about 1 to about 6 moles of an aldehyde
monomer for each mole of triazine monomer, and an acid catalyst
having a pKa from greater than 3.8 to 11, heating the reaction
mixture to a temperature of about 120.degree. C. to about
165.degree. C. and substantially completing reaction of arylhydroxy
monomer in the reaction mixture.
[0015] In yet another aspect of this invention, the
triazine-phenol-aldehyde condensate as described herein, either
alone or in admixture with another epoxy curing agent and/or
another fire-retardant, may be used as a fire-retardant curing
agent for epoxy resins.
[0016] In another aspect, a prepreg of a porous substrate is
provided and includes a curable epoxy resin and a condensate of a
reaction mixture a triazine monomer, an arylhydroxy monomer, an
aldehyde monomer and an acid catalyst having a pKa of greater than
3.8 as the curing agent alone or in combination with another curing
agent.
[0017] In another aspect, a laminate is provided including one or
more prepregs impregnated with an epoxy resin and a condensate of a
reaction mixture a triazine monomer, a phenol monomer, an aldehyde
monomer and an acid catalyst having a pKa of greater than 3.8 alone
or together with another curing agent wherein the epoxy resin
composition is cured.
[0018] In another aspect, a glycidylated triazine-phenol-aldehyde
condensate is provided in a reaction mixture, wherein the
condensate prior to glycidylation is a reaction mixture comprising
a triazine monomer, a phenol monomer, an aldehyde monomer and an
acid catalyst having a pKa value range from greater than 3.8, and
comprises up to about 28 wt. % of nitrogen, a melt viscosity of
less than 3,000 cps at 175.degree. C., and a solubility of up to
about 80 wt. % solids dissolved for 120 hours or greater in one or
more organic solvents having one or more functionalities selected
from the group consisting of an ether functionality, a ketone
functionality, an alcohol functionality, an ester functionality,
and combinations thereof.
[0019] In another aspect, a composition suitable for electronic
applications is provided and includes an epoxy resin wherein for
each 100 parts of epoxy resin the composition contains about 0-30
parts of a phenolic-formaldehyde novolac, optionally an epoxy
curing accelerator, and about 30 to 60 parts of a
triazine-phenol-aldehyde condensate in a reaction mixture
comprising a triazine monomer, a phenol monomer, an aldehyde
monomer, and an acid catalyst having a pKa value range from greater
than 3.8 to about 11, wherein the triazine-phenol-aldehyde
condensate and comprises up to about 28 wt. % of nitrogen, a melt
viscosity of less than 3,000 cps at 175.degree. C., and a
solubility of up to at least about 80 wt. % solids dissolved for
120 hours or greater in one or more organic solvents having one or
more functionalities selected from the group consisting of an ether
functionality, a ketone functionality, an alcohol functionality, an
ester functionality, and combinations thereof.
[0020] In another aspect, a method for the preparation of a
condensate product is provided and includes charging to a reaction
vessel to form a reaction mixture of a triazine monomer, about 3 to
about 30 moles of a phenol monomer for each mole of triazine, an
acid catalyst having a pKa from 6 to about 11, and from about 1 to
about 6 moles of an aldehyde monomer for each mole of triazine
monomer, heating the reaction mixture at a temperature from about
165.degree. C. to about 180.degree. C., removing the phenol monomer
and any water from the reaction mixture, and steam sparging the
reaction mixture.
[0021] In another aspect, a method for the preparation of
condensate product is provided and includes charging to a reaction
vessel to form a reaction mixture of an aldehyde modified triazine
monomer and about 3 to about 30 moles of a phenol monomer for each
mole of aldehyde modified triazine monomer and heating the reaction
mixture to a temperature of about 130.degree. C. to about
180.degree. C. and substantially completing reaction of phenol
monomer in the reaction mixture.
DETAILED DESCRIPTION OF THE INVENTION
[0022] Embodiments of the invention are directed to condensates,
methods for making the condensates, and application of the
condensates in epoxy resins, prepregs of porous substrates, and
laminates.
[0023] In one aspect, the present invention provides for a
triazine-arylhydroxy-aldehyde condensate, such as a
triazine-phenol-aldehyde (T-P-A or TPA) condensate and processes
for the preparation of the triazine-arylhydroxy-aldehyde
condensate. The triazine-arylhydroxy-aldehyde condensate may be
formed from a reaction mixture of a triazine monomer, an
arylhydroxy monomer, and an aldehyde monomer, and an acid catalyst
having a pKa of greater than 3.8.
[0024] Through the choice of acid catalysts with a pKa value of
greater than 3.8, the triazine-arylhydroxy-aldehyde condensates
exhibit a viscosity range of 3000 cps or less at 175.degree. C.,
such as from about 200 cps to about 2000 cps, and contain from
about 8 wt. % to about 28 wt. % nitrogen content, for example, from
greater than about 10 wt. % to about 24 wt. % nitrogen content. The
triazine-arylhydroxy-aldehyde condensates described herein may be
substantially free of water as further described herein and may
have about 2 wt. % or less of free arylhydroxy monomer.
[0025] Additionally, it was surprisingly and unexpectedly
discovered that the triazine-arylhydroxy-aldehyde condensates
formed by the components and processes described herein have
improved solubility over those in the prior art. The
triazine-arylhydroxy-aldehyde condensates described herein were
observed to stay dissolved in an organic solvent at up to 80 wt. %
solids (or higher) for at least 120 hours (5 days) before
cloudiness set in, or precipitation, in the form of a white circle
at the bottom of the vial, began.
[0026] In particular, the triazine-arylhydroxy-aldehyde condensates
described herein were observed to provide an improved solubility by
dissolving completely in one or more organic solvents having one or
more functionalities selected from the group of an ether
functionality, a ketone functionality, an alcohol functionality, an
ester functionality, and combinations thereof, of which a ketone
functionality solvent, such as methyl ethyl ketone (MEK) may be
used. The condensates formed as described herein were observed to
have a solubility from less than 10 wt. % solids up to 80 wt. %
solids, such as from about 33 wt. % solids to about 75 wt. %
solids, to give a transparent solution (no turbidity) for 120 hours
or greater. Other condensates formed by the processes described
herein were observed to have a solubility up to 80 wt. % solids
(and sometimes greater) for at least 500 hours.
[0027] In comparison, most of the condensates from prior art
processes typically dissolve only up to 40 wt. % (solids) and in
selected cases roughly about 60 wt. % in common solvents such as
MEK.
[0028] The processes for forming the condensates as described
herein also allow for the production of the condensates in large
reaction vessels with improved control over melt viscosity than the
prior methods to produce similar condensates.
[0029] In one aspect, the triazine-arylhydroxy-aldehyde condensate
is formed from a reaction mixture of a triazine monomer, an
arylhydroxy monomer, and an aldehyde monomer, and an acid catalyst
having a pKa of greater than 3.8, which are described as follows.
In one embodiment, the triazine monomer may include an aldehyde
functional group, such as an aldehyde modified triazine monomer.
The aldehyde modified triazine monomer may be used in place of a
separate triazine monomer and a separate aldehyde monomer to form
the condensate.
The Triazine Monomer
[0030] The triazine monomer may be a triazine compound or a
triazine derivative. An example of a triazine compound is melamine
and an example of a triazine derivative is a melamine derivative.
The triazine derivative may also be an aldehyde modified triazine
monomer, such as hexamethoxymethylmelamine (HMMM) or
hexamethylolmelamine. The aldehyde modified triazine monomer may
provide for the aldehyde presence in the
triazine-arylhydroxy-aldehyde condensate and remove the need for a
separate aldehyde monomer.
[0031] One embodiment of the triazine monomer may be represented by
the following formula:
##STR00001##
wherein R.sub.1 and R.sub.2 may each be independently a hydrogen
atom or a functional group selected from the group of an amino
group (--NH.sub.2), an alkyl group having 1 to 4 carbon atoms, a
phenyl group, a vinyl group (--CH.dbd.CH.sub.2), or a group
containing a combination of the functional groups.
[0032] Suitable compounds that may be used as the triazine monomer
include compounds selected from the group of aminotriazine,
4-methyl-1,3,5-triazine-2-amine,
2-amino-4,6-dimethyl-1,3,5-triazine, melamine,
hexamethoxymethylmelamine, hexamethylolmelamine, guanamine,
acetoguanamine, propioguanamine, butyroguanamine, benzoguanamine,
vinylguanamine, 6-(hydroxyphenyl)-2,4-diamino-1,3,5-triazine, and
combinations thereof.
[0033] The triazine monomer may also be a mixture of one or more
triazine compounds, such as melamine, and a second amine compound,
such as benzoguanamine or acetoguanamine. The quantity of melamine
is at least 50% by weight of the mixture and the second amine
compound may be from about 0.5% to not more than about 50% by
weight of the mixture. In one embodiment, the amount of the second
amine compound may be from about 1% to not more than about 25% by
weight of the mixture.
[0034] The triazine monomer may also be a mixture of melamine and
two or more amines, such as benzoguanamine and acetoguanamine,
wherein the first of one or more amines is not more than about 35%
by weight of the mixture, the second of the one or more amines is
not more than 35% by weight of the mixture, and the quantity of
melamine is at least 50% by weight of the mixture. In one
embodiment, the benzoguanamine and acetoguanamine combined are not
more than 25% by weight of the mixture and the melamine is at least
75% by weight of the mixture.
The Arylhydroxy Monomer
[0035] The arylhydroxy monomer may be any suitable aromatic
monomer, such as a phenol monomer. The quantity of an arylhydroxy
monomer in the reaction mixture for forming the condensates as
described herein may be from about 3 to about 30 moles, such as
from about 9 to about 14 moles, of the arylhydroxy monomer for each
mole of triazine monomer. Thus, the molar ratio of arylhydroxy
monomer to triazine monomer may be from about 3:1 to about 30:1,
such as from about 9:1 to about 14:1. This quantity of arylhydroxy
monomer in the reaction mixture, i.e., charged to the reaction
vessel, may be greater than the amount which reacts in the
formation of the condensate. Free, non-reacted, arylhydroxy
monomer, such as phenol, may be distilled out of the reaction
mixture after completion of the condensate reaction.
[0036] Non-limiting examples of arylhydroxy monomers include phenol
(phenolic) monomer type compounds. A phenol monomer type compound
includes compounds having one or more aromatic hydroxyl groups per
molecule, including, for example, mononuclear or binuclear,
monohydroxyphenols or dihydroxyphenols (diphenolics, benzene
diols). Phenol monomer type compounds having at least one ortho or
para position available for bonding are preferred compounds. The
phenol monomer type compounds may be an unsubstituted or
substituted compound, for example, with an alkyl group, a phenyl
group, a hydroxybenzene group, an alkoxy group, and combinations
and subsets thereof. The phenol monomer type compound may also
include compounds having up to about 15 carbon atoms such as up to
about 8 carbon atoms.
[0037] Suitable phenol monomers include compounds selected from the
groups of cresols, xylenols, bis-phenols, alkylated bisphenols,
alkoxyphenols, dihydroxy benzene (diphenolics, benzene diols),
naphthols, biphenols, alkylated biphenols, trisphenols, and
combinations thereof.
[0038] Examples of suitable phenol monomers may include compounds
represented by the following formula:
##STR00002##
and X is an integer of 1 or 2, R.sub.3 and R.sub.4 are each
independently a functional group selected from the group of a
hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkyl
group having 1 to 4 carbon atoms with at least one carbon atom
being substituted with a hydroxybenzene group, an alkoxy group
having 1 to 4 carbon atoms, a phenyl group, a hydroxybenzene group,
and combinations and subsets thereof. The R.sub.3 and R.sub.4
functional groups may jointly form a common aromatic ring with or
without a hydroxyl group.
[0039] Specific examples of suitable compounds that may be used as
the phenol monomer include compounds selected from the group of
phenol, para-phenylphenol, 3-ethylphenol, 3-isopropylphenol,
3-methylphenol, 4-methylphenol, 2,6-dimethylphenol,
2,4-dimethylphenol, 2-methoxyphenol, 3-methoxyphenol, bisphenol-A,
resorcinol, catechol, alpha-naphthol, and combinations thereof, of
which phenol is preferred.
[0040] Mixtures of arylhydroxy monomers may also be used. For
example, a mixture of at least 90% by weight of phenol and 10% or
less by weight of an alkyl phenol, an alkoxy phenol, a dihydroxy
phenol, a substituted dihydroxy phenol, and combinations and
subsets thereof, may also be used as the phenol monomer.
The Aldehyde Monomer
[0041] The term "aldehyde monomer" herein includes compounds having
one or more aldehyde functional groups (--CHO) and any compounds
yielding aldehydes. The aldehyde monomer may be represented by the
formula R--CHO, and R may be an aliphatic or aromatic organic
functional group. The aldehyde monomer may be a dialdehyde such as
glyoxal. Suitable aldehydes include compounds selected from the
group of formaldehyde, acetaldehyde, i-butyraldehyde
(isobutyraldehyde), benzaldehyde, acrolein, crotonaldehyde,
salicylaldehyde, 4-hydroxybenzaldehyde, furaldehyde,
pyrrolaldehyde, cinnamaldehyde, terephthaldialdehyde, glyoxal, and
combinations thereof. Compounds yielding aldehydes include
compounds selected from the group of paraformaldehyde,
trioxymethylene, paraldehyde, and combinations thereof.
[0042] The quantity of aldehyde monomer used in manufacture of the
condensate as described herein varies from about 1 mole to about 6
moles, such as from about 2 to about 3.5 moles, for each mole of
the triazine monomer charged to the reaction vessel. Thus, the
molar ratio of aldehyde monomer or aldehyde functional groups to
triazine monomer may be from 1:1 to 6:1, such as from 2:1 to 7:2.
The quantity of aldehyde may be provided to a reaction mixture in
one or more separate additions.
[0043] In one embodiment of the aldehyde monomer, the monomer may
be a mixture of formaldehyde and one or more aldehydes. Suitable
aldehydes for the mixture may include acetaldehyde, i-butyraldehyde
(isobutyraldehyde), benzaldehyde, acrolein, crotonaldehyde, and
combinations thereof. The one or more aldehydes comprise from about
0.1 mole % to about 20 mole %, such as from about 1 mole % to about
10 mole % of the mixture.
[0044] The aldehyde monomer may be introduced neat or as about 20%
to about 50% solution in phenol to facilitate metering in the
reaction mixture. The aldehyde may be introduced in an aqueous
solution of 30 to 45% which may include an organic solvent from 5
to 15%. For example, if formaldehyde is the aldehyde monomer,
formaldehyde may be introduced as a 37% aqueous solution with 11%
methanol. Formaldehyde may also be generally charged to the
reaction mixture as 50 wt. % formalin. Formalin generally contains
small quantities of formic acid with about 0.03% of formic acid
being typical in a 50% formalin solution.
[0045] Further description of arylhydroxy monomers, triazine
monomers, and aldehyde monomers are more fully detailed in co-owned
U.S. Pat. No. 6,605,354, issued on Aug. 12, 2003, entitled "High
Nitrogen Containing Triazine-Phenol-Aldehyde Condensate", which is
incorporated by reference to the extent not inconsistent with the
recited claims and description herein.
The Acid Catalyst
[0046] The methods as described herein for manufacture of the
triazine-arylhydroxy-aldehyde condensate may utilize an acid
catalyst having a pKa acidity value of greater than 3.8. The pKa
acidity value, referred to as pKa or pKa value, may be from greater
than 3.8 to about 11. In one composition and method for forming the
condensate, a low pKa acidity value catalyst may be used having a
pKa value from greater than 3.8 to 6, such as from about 4 to about
5, for example, from about 4.1 to about 4.8. In another composition
and method for forming the condensate, a high pKa acidity value
catalyst may be used having a pKa value from greater than 6 to
about 11, for example, from about 8 to about 10.
[0047] Suitable catalysts having the desired pKa acidity values,
such as from greater than 3.8 to 6, may be organic acids. Suitable
organic acids include monocarboxylic acids, dicarboxylic acids, and
combinations thereof. Examples of suitable monocarboxylic acids
include, for example, acetic acid, adipic acid, ascorbic acid,
benzoic acid, cinnamic acid, adipamic acid, o- and p-aminobenzoic
acid, anisic acid, anisylpropionic acid, barbituric acid, butyric
acid, isobutyric acid, caproic acid, isocapropic acid,
chlorobutyric acid, chlorocinnamic acid, chlorophenylacetic acid,
(chlorophenyl)propionic acid, trans-cinnamic acid, trans-crotonic
acid, dihydroxybenzoic acid (3,4 and 3,5), ethylbenzoic acid,
ethylphenylacetic acid, trans-furmaric acid, gallic acid,
glutaramic acid, heptanoic acid, hexahydrobenzoic acid, hexanoic
acid, m-hydroxybenzoic acid, p-hydroxybenzoic acid, hydroxybutyric
acid, mesitylenic acid, naphthoic acid, o-nitrophenylacetic acid,
nonanic acid, octanoic acid, phenylacetic acid, propionic acid,
iso-propylbenzoic acid, pyridinecarboxylic acid, suberic acid,
toluic acid (meta and para), trimethylacetic acid, valeric acid,
vinylacetic acid, and combinations thereof.
[0048] Suitable dicarboxylic acids include, for example, acids
selected from the group of adipic acid, succinic acid, glutaric
acid, methylsuccinic acid, and combinations thereof.
[0049] Suitable acid catalysts having the pKa value of greater than
6, for example, include compounds selected from the group of
phenol, cresols, vanilla, acetylacetone, glycine, cysteine,
2,3-dichlorophenol, hydroquinone, chlorophenols, naphthols,
nitrophenols, tryptophan, tyrosine, xanthine, and combinations
thereof. In one embodiment of the acid catalyst having pKa values
of greater than 6, the acid catalyst may be the phenol monomer as
described herein.
[0050] The acid catalyst may be present from greater than 0.1% to
less than 1%, such as from about 0.2% to about 0.4% based on the
weight of the arylhydroxy monomer (phenol monomer) in the reaction
mixture. If the acid catalyst comprises the phenol monomer, no
additional acid catalyst amount may need to be added to the
reaction mixture.
[0051] When the phenol monomer is used as both the acid catalyst
and as the phenol monomer, the reaction to form the condensate may
be considered self-catalyzing, and under such circumstances a
separate acid and/or base catalyst is not needed.
[0052] Optionally, additional compounds may be used with the
reaction mixture and/or the epoxy resin. One additional compound is
a stabilizer that may be a non-reactive diluent that can reduce the
viscosity of the condensate or resin. The stabilizer may be an
organic compound, and may be cyclical, acyclical, aliphatic, or
aromatic in form. Suitable stabilizers may include, and are not
limited to, the following classes of compounds: esters, hydroxyaryl
moieties, dihydroxyaryl moieties, amides, alcohols, ketones, and
combinations and subsets thereof. Examples of suitable stabilizer
groups include alkylphenols, glycols, glycol ethers, and
combinations and subsets thereof. Examples of stabilizers include
compounds selected from the group of cresol, N-methyl pyrrolidone,
phenol, hydroquinone, triethylcitrate, butyrolactone, glycerol,
ethylene glycol, and combinations thereof. The stabilizer may be
added to the reaction mixture from 0.1 wt. % to 2 wt. % of the
reaction mixture, such as the triazine-phenol-aldehyde condensate.
The stabilizer is preferably added when a solid of the condensate
is to be formed and maintained. If a liquid solution of the
condensate is to be performed, preferably a solvent is added to the
condensate.
[0053] Optionally, a base catalyst may be introduced with the acid
catalyst described herein. The quantity of base catalyst, also
referred to as a catalytically effective quantity of amine
catalyst, will typically vary from about 0.01% to about 1% based on
the weight of the arylhydroxy monomer charged and preferably from
about 0.08% to about 0.3%, for example, from about 0.1% to about
0.2%. The base catalyst may have a pK basicity, or pKb from about 7
to about 11.5.
[0054] The base catalyst may be an aliphatic, a cycloaliphatic,
and/or a heterocyclic amine having a pK basicity (pKb) of 10 or
more, and may further be a secondary or tertiary amine. A tertiary
amine may have the formula R.sub.3N, with each R may be an alkyl
functional group having one to seven carbon atoms, and the nitrogen
atom may be part of a heterocyclic ring. In this regard, each of
the alkyl groups may be the same or different. A secondary amine
having a pKb of 10 or more may have the formula R.sub.1R.sub.2NH,
with each R may be an alkyl functional group of 2 to 4 carbon
atoms. Examples of amines for use as the base catalyst include
triethylamine, tributylamine, N-ethyl piperidine,
2-di(n-butylamino)ethanol, 2-di(isopropylamino) ethanol,
N-methylpyrrolidine, N,N-dimethyl cyclohexylamine, diethylamine,
di-n-butylamine, diisopropylamine, piperidine, pyrrolidine, and
combination thereof.
[0055] Examples of amines having a pK basicity of less than 10
include, and are not limited to, N-methylmorpholine, N-methyl
diethanolamine, triethanolamine, N,N'-dimethylpiperazine,
4-methylpyridine, 2,4-dimethylpyridine, N,N-diethylaniline, and
N,N-dimethylbenzylamine, and combinations thereof, may be used as
the base catalyst.
The Triazine-Arylhydroxy-Aldehyde Condensate
[0056] In one embodiment, the triazine-arylhydroxy-aldehyde
condensate may be represented by the following formula:
##STR00003##
[0057] The R.sub.7 and R.sub.8 functional groups of the formula
(III) may each independently be a hydrogen atom or a functional
group having formula (IV):
##STR00004##
where n may be an integer of 0 to 20 and X is an integer of 1 or 2.
The R.sub.5 and R.sub.6 functional groups may be independently a
hydrogen atom or a functional group selected from the group of an
alkyl group having 1 to 4 carbon atoms, an alkyl group having 1 to
4 carbon atoms with at least one carbon atom being substituted with
a hydroxybenzene group, an alkoxy group having 1 to 4 carbon atoms,
a phenyl group, a hydroxybenzene, and combinations and subsets
thereof. The R.sub.5 and R.sub.6 functional groups may jointly form
a common aromatic ring with or without a hydroxyl group.
[0058] The R.sub.7 and R.sub.8 functional groups may also jointly
form a benzoxazine functional group represented by the formula:
##STR00005##
[0059] In Formula (V), the R.sub.5 and R.sub.6 functional groups
are described above with regard to formula (IV), and Y is an
integer of 0 or 1. The benzoxazine functional group may be formed
during the high pKa process as described herein when the triazine
monomer and aldehyde monomer comprise an aldehyde modified triazine
monomer such as HMMM. Also, the benzoxazine functional group may be
formed when the para position of the phenol monomer is not
available for reacting with the aldehyde as in a para substituted
phenol monomer such as para-cresol. If the R.sub.8 functional group
is not part of formula (V), the R.sub.8 functional group may be a
hydrogen atom or a functional group having the formula (IV).
[0060] If the R.sub.7 and R.sub.8 functional groups of the formula
(III) are both hydrogen atoms, then between the R.sub.9 and
R.sub.10 functional groups of the formula (III), at least one of
the R.sub.9 and R.sub.10 functional groups may be a functional
group having the formula (V) or may be a functional group selected
from the group of --NHR.sub.11, --N(R.sub.11).sub.2, and
combinations thereof. The R.sub.11 functional group may be a
hydrogen atom or have the formula (IV).
[0061] The R.sub.9 and R.sub.10 functional groups may be each
independently be a hydrogen atom or a functional group selected
from the group of --NH.sub.2, --NHR.sub.11, --N(R.sub.11R.sub.12),
--N(R.sub.11).sub.2, --N(R.sub.12).sub.2, an alkyl group having 1
to 4 carbons, a phenyl group, a vinyl group (--CH.dbd.CH.sub.2), a
functional group having the formula:
##STR00006##
a benzoxazine functional group of formula (V), and combinations
thereof and subsets thereof. R.sub.11 and R.sub.12 may each
independently be a hydrogen atom or a functional group having the
formula (IV).
[0062] One example of an embodiment of the condensate formed by the
processes described herein may be represented by the following
formula:
##STR00007##
where the R.sub.13 functional group may have the formula (IV) given
above or may jointly form with the R.sub.14 functional group a
benzoxazine functional group having the formula (V) given above. If
the R.sub.14 functional group is not part of formula (V), the
R.sub.14 functional group may be a hydrogen atom or a functional
group having the formula (IV). The R.sub.15 and R.sub.16 functional
groups may each independently be a hydrogen atom or a functional
group having the formula (IV). The R.sub.15 and R.sub.16 functional
groups may also jointly form a benzoxazine functional group having
formula (V). R.sub.17 and R.sub.18 may each independently be a
hydrogen atom or a functional group having the formula (IV).
Similarly, the R.sub.17 and R.sub.18 may also jointly form a
benzoxazine functional group having formula (V).
[0063] The condensate in formula (VII) may be obtained by reacting
either melamine with phenol monomer and formaldehyde monomer or a
melamine derivative, such as HMMM, with a phenol monomer. It is to
be noted that if an aldehyde other than formaldehyde is utilized in
these reactions, the CH.sub.2 group that is given in the formulas
(IV), (V) and (VI) will be replaced with --CH(R) where the R group
originates from the R group of the aldehyde represented by the
formula R--CHO. The R could be an aliphatic or aromatic group
depending on whether the aldehyde is aliphatic or aromatic. For
example, R is a methyl group when the aldehyde is acetaldehyde and
R is a phenyl group when the aldehyde is benzaldehyde. The most
preferred aldehyde is formaldehyde.
[0064] Additionally, condensates may be prepared with low
arylhydroxy content and substantially free of water. After the
removal of the non-reacted (free) arylhydroxy monomer, such as
phenol, from the reaction mixture in the processes described
herein, the free arylhydroxy monomer content of the
triazine-arylhydroxy-aldehyde condensate may be less than about 2
wt. %, such as less than about 0.75% by weight of the condensate.
The triazine-arylhydroxy-aldehyde condensate formation processes
described herein have substantially all of the free water removed,
for example, less than about 1 wt. % and preferably less than 0.5
wt. % of water remains in the condensates.
[0065] The triazine-arylhydroxy-aldehyde condensates, as described
herein and further shown in the examples herein, may have a
solubility of up to at least 60% by weight and preferably greater
than 80% by weight of the condensate in one or more organic
solvents having one or more functionalities selected from the group
of an ether functionality, a ketone functionality, an alcohol
functionality, an ester functionality, and combinations thereof,
for at least 120 hours, such as for at least 500 hours. For
example, the condensate solutions prepared at 33 wt. % solids or
higher may remain in dissolved state without getting cloudy or
precipitating in the form of a white circle at the bottom of the
vial for at least 120 hours and in many instances for an indefinite
period of time.
[0066] The one or more organic solvents may each respectively have
one or more functionalities selected from the group of an ether
functionality, a ketone functionality, an alcohol functionality, an
ester functionality, and combinations thereof, of which a ketone
functionality solvent, such as methyl ethyl ketone (MEK) may be
used. Suitable solvents may be selected from a group of a ketone
solvent, an alcohol solvent, an ether solvent, a glycol ether
solvent, an ester solvent, a glycol ester solvent, and combinations
thereof. Each of the molecules of the solvents described herein may
have from 1 to 12 total carbon atoms, such as from 3 to 10 carbon
atoms. Examples of suitable solvents may include a compound
selected from the group of methyl ethyl ketone (MEK), methyl
isobutyl ketone (MIBK), acetone, methanol, isopropyl alcohol, 1
methoxy-2-propanol, and combinations thereof.
[0067] The triazine-arylhydroxy-aldehyde condensates as described
herein may contain up to about 28 wt. % of nitrogen, such as from
about 8 wt. % to about 28 wt. % of nitrogen, for example, from
about 8 wt. % to about 25 wt. %. In one embodiment, the
triazine-arylhydroxy-aldehyde condensates as described herein may
contain from greater than about 10 wt. % to about 24 wt. % of
nitrogen based on the weight of the condensate.
[0068] The triazine-arylhydroxy-aldehyde condensates described
herein may have a viscosity below 3,000 cps and even less than
1,700 cps, such as from about 200 cps to about 1200 cps, at
175.degree. C. The process for forming the
triazine-arylhydroxy-aldehyde condensates was also observed to have
provided for an improved viscosity control over prior resins. The
improved viscosity control was achieved by controlling the increase
in the viscosity of the resin to 20% or less, such as less than
10%, during and subsequent to arylhydroxy removal until the
condensate is finished as a solid by heating at temperatures up to
165.degree. C. during the final stages of production process in
large reactors. As such, triazine-arylhydroxy-aldehyde condensates,
such as melamine-phenol-formaldehyde condensates, formed with the
components described herein, exhibit a reduced increase of
viscosity when held at process temperatures at 165.degree. C.
instead of 175.degree. C.
[0069] In contrast, it is believed that prior art TPA condensates
undergo molecular rearrangements that result in a viscosity
increase and a reduced solubility in common solvents when held
(greater than 1 hour) at an elevated temperature, such as
175.degree. C. or greater, over time as a result of resin
degradation in the phenol removal step of the process.
[0070] Also, it has been observed that the
triazine-arylhydroxy-aldehyde condensates obtained by the high pKa
processes described herein (pKa of greater than 6) unexpectedly and
surprisingly exhibited increased reactivity, including self-curing
reactivity and exothermic heat generation, than condensates made
with added catalysts that have a pKa value of less than 5.
[0071] For example, a DSC (differential scanning calorimeter)
analysis of a condensate formed from a HMMM-phenol reaction mixture
described herein, such as in Example 9A, was observed to have an
exothermic reaction at around 183.degree. C. This exothermic
reaction indicates a self-curing reaction that was not observed in
prior art processes or the low pKa process of the current
invention.
[0072] Further examples of self-curing reactions were observed in
Examples 9A and 3. The condensate from the HMMM-phenol reaction
mixture, when heated at 175.degree. C. for only about 4 hours in
Example 9A, was observed to have a self-curing type reaction which
is evidenced by hardening of the resin. The condensate made from
melamine, phenol and formaldehyde reaction mixture in Example 3,
was observed to undergo a viscosity increase of greater than 100%
when heated at 175.degree. C. for 7 hours.
[0073] As the triazine-arylhydroxy-aldehyde condensates form such
processes described herein have been observed to exhibit
self-curing like behavior when heated at temperatures of above
165.degree. C., under such conditions the condensate may be
designated as a self-curing reaction and/or a self-curing
condensate.
[0074] In view of such reactivity, the
triazine-arylhydroxy-aldehyde condensates made from the high pKa
processes described herein may be prepared as a solution of the
triazine-arylhydroxy-aldehyde condensates in one or more organic
solvents having one or more functionalities selected from the group
of an ether functionality, a ketone functionality, an alcohol
functionality, an ester functionality, and combinations thereof, or
formed as a solid with a viscosity stabilizer, to preserve a
desired viscosity and reduce the reactivity of the condensate.
[0075] It has also been observed that the condensates formed by the
processes described herein exhibited improved color stability over
time. The condensates exhibited a Gardner color scale number of
less than 3, and maintained a Gardner color scale number of less
than 3, such as less than 1, for at least 150 days. Additionally,
the surprisingly and unexpectedly improved color stability was also
observed by the condensates having a color change on the Gardner
color scale number of less than 0.5, such as less than 0.2, for at
least 150 days. Alternatively, the improved color stability was
also observed by the condensates having a color change on the Hazen
Color scale value (also referred as APHA) of less than 20, such as
less than 8, for at least 150 days.
[0076] The Gardner color scale numbers and Hazen Color scale values
were observed for pilot plant batch results of Entry Numbers 1 and
2 (as shown in Tables II and III herein) formed using the process
in Example 2. For Entry Number 1, the initial Gardner color scale
number was observed to be 0.7 and the initial Hazen Color scale
value was observed to be 153, and when measured 154 days later, the
Gardner color scale number was observed to be 0.8 and the Hazen
Color scale value was observed to be 156. For Entry Number 2, the
initial Gardner color scale number was observed to be 0.53 and the
initial Hazen Color scale value was observed to be 125, and when
measured 154 days later, the Gardner color scale number was
observed to be 0.6 and the Hazen Color scale value was observed to
be 132.
[0077] The color scale values of the condensates measured above
were analyzed by dissolving the respective condensates in reagent
grade acetone to prepare a 30% solids solution (1 g resin, 2.33 g
acetone or 0.75 g in 1.75 g acetone), which was then mixed and
dissolved completely at ambient temperature and filtered using 0.45
micron syringe filter before being measured for respective colors
using a LICO.RTM. 100 LCM Plus colorimeter from Dr. Lange GmbH
& Co. KG, of Germany. The LICO.RTM. 100 LCM Plus colorimeter
can measure up to five different color values including Gardner
Color values and Hazen Color values (also referred as APHA). The
colorimeter measures the Gardner color value scale having a range
from 0 to 18 with an accuracy of about +/-0.1. The colorimeter
measures the Hazen (APHA) color value scale having a range from 0
to 1000 with an accuracy of about +/-2. At least three readings
were recorded for each color scale and the results were averaged.
While the average variation in APHA color value between
measurements was about 27, the variation in Gardner was about
0.1.
[0078] Additionally, it has been observed that the resins obtained
by a high pKa process described herein (pKa of greater than 6) were
unexpectedly and surprisingly observed to have higher T.sub.d
(temperature at which 5% weight loss occurs) and yield
significantly higher glass transition temperatures upon curing with
epoxies than the triazine-phenol-aldehyde condensates made by prior
art processes. The T.sub.d of these resins were found to be greater
than 300.degree. C., which is at least 15.degree. C. higher than
the resins made by the low pKa process. Also, these resins, when
cured with an epoxy cresol novolac, yielded unexpectedly high
T.sub.g of 189.degree. C. to 197.degree. C.
[0079] The triazine-arylhydroxy-aldehyde condensate as described
herein may be further reacted with additional formaldehyde, for
example, 5 to 15%, based on the weight of the initial amount of
formaldehyde in order to raise the glass transition temperature of
cured compositions of the triazine monomers, phenol monomers, and
aldehyde monomers condensate and an epoxy resin.
Methods for Forming Triazine-Arylhydroxy-Aldehyde Condensates
[0080] Embodiments of the condensates of the triazine monomers,
arylhydroxy monomers, and aldehyde monomers, may be prepared by the
process embodiments as follows. While the following processes are
described as using a phenol monomer as the arylhydroxy monomer, the
invention contemplates that arylhydroxy monomers other than phenol
may be used in the processes described below, and the following
description should not be construed or interpreted as limiting the
scope of the invention.
[0081] In all of the methods, the molar ratio of the reactants may
be from about 3 moles to about 30 moles, such as from about 9 to
about 14 moles of a phenol monomer for each mole of a triazine
monomer charged to a vessel and from about 1 to about 6 moles, such
as from about 2 to about 3.5 moles, of an aldehyde monomer for each
mole of triazine charged to a vessel.
[0082] The various reaction steps for preparation of the
condensates by the processes as described herein may be conducted
in the same reaction vessel. A non-reactive atmosphere, such as
nitrogen gas or a noble gas, is optionally employed to minimize
oxidation of aldehyde and discoloration of product. In the order of
charging ingredients to the reaction vessel, the aldehyde is
typically added after the triazine, phenol and catalyst except in
the high pKa acid catalyst method when the high pKa catalyst may be
added with or after the other components. In each of the methods
for the manufacture of the condensates, when aldehydes other than
formaldehyde are used, such other aldehydes are typically reacted
at a temperature of about 100.degree. C. or less prior to the
addition of formaldehyde.
The Low pKa Value Acid Catalyst Method
[0083] In the processes described herein for making the condensate
for the low pKa value acid catalyst method, the pH of the mixture
of arylhydroxy monomer and acid catalyst may be from about 2 to
about 4.
[0084] In one embodiment of the low pKa acid catalyst method, the
initial reaction mixture includes an acid catalyst having a pKa
acidity of from greater than about 3.8 to 6, such as a pKa acidity
from about 4.1 to about 4.8. The quantity of acid varies and is
generally from about 0.1% to 1% by weight (wt. %), such as from
about 0.1 wt. % to 0.5 wt. %, for example, from about 0.2 wt. % to
0.4 wt. %, based on the quantity of arylhydroxy monomer charged.
Suitable acid catalysts that may be used in the low pKa acid
catalyst method include the acid mentioned herein, and preferably
include an acid selected from the group of acetic acid, adipic
acid, ascorbic acid, benzoic acid, cinnamic acid, succinic acid,
and combinations thereof, among others.
[0085] One embodiment of the process to form a condensate from
triazine monomers, arylhydroxy monomers, and aldehyde monomers
includes charging the triazine monomer to a reaction vessel,
charging from about 3 to about 30 moles, such as about 9 to about
14 moles of an arylhydroxy monomer for each mole of triazine
monomer with about 0.1 wt. % to 0.5 wt. % of the acid catalyst
described herein relative to the weight of the arylhydroxy monomer.
The acid catalyst may have a pKa of about 3.8 to 6, such as a pKa
acidity from about 4.1 to about 4.8. In one example, the triazine
monomer is triazine, the arylhydroxy monomer is phenol, the
aldehyde monomer is formaldehyde, and benzoic acid is the acid
catalyst.
[0086] The reaction mixture is then heated at a temperature of
about 70.degree. C. to 110.degree. C. and then about 50% to 63% of
the total from about 1 mole to 6 moles, such as from about moles
2.2 to 3.2 moles (i.e., from about 1.1 to about 2.0 moles for the
from about moles 2.2 to 3.2 moles), of aldehyde monomer for each
mole of triazine monomer may be then charged to the reaction vessel
in one or more additions at this temperature. Alternatively, the
entire aldehyde monomer or the aldehyde modified triazine compound,
such as in HMMM described above, may be charged to the reaction
vessel on one addition process. The reaction mixture is then heated
to a temperature of about 120.degree. C. to about 140.degree. C. to
effect copolymerization of the three monomers and to remove water
and the temperature is maintained for about 1 to about 2 hours.
[0087] The reaction mixture is then cooled to a temperature which
does not exceed about 110.degree. C., such as that of about
70.degree. C. to about 110.degree. C., and the remainder of the
aldehyde monomer is added. The reaction mixture is then heated to a
temperature above 120.degree. C. to continue copolymerization and
remove water and the temperature is maintained for about 1 to about
2 hours until the reaction of the arylhydroxy monomer is
substantially complete.
[0088] The reaction mixture may then be heated to a temperature of
about 145.degree. C. to about 165.degree. C. to continue removing
water from the reaction mixture. The reaction mixture is then
distilled under full vacuum to remove most of the non-reacted
arylhydroxy monomer. Optionally, the reaction mixture may then be
further heated to further remove additional amounts of the
arylhydroxy monomer from the condensate, for example, to a
temperature not exceeding 180.degree. C. for phenol removal, when
steam sparging is adopted to remove trace amounts of the
arylhydroxy monomer from the condensate.
[0089] The recovered condensates were observed to have a range of
viscosity from about 200 cps to about less than 3000 cps, for
example as from about 1100 cps to about 1700 cps, and contain from
about 8 wt. % to about 28 wt. % nitrogen content, for example, from
greater than 10 wt. % to about 23 wt. % nitrogen content. The
recovered condensates exhibited a solubility in one or more organic
solvents having one or more functionalities selected from the group
of an ether functionality, a ketone functionality, an alcohol
functionality, an ester functionality, and combinations thereof, of
which methyl ethyl ketone (MEK) is preferably used, up to 80 wt. %
solids (or higher), such as from about 33 wt. % solids to about 75
wt. % solids to give a transparent solution (no turbidity) that
stayed dissolved for an indefinite period of time, such as greater
than or equal to 120 hours. For example, the recovered condensates
in the MEK solutions from about 33 wt. % solids to 80 wt. % and
higher stayed dissolved for an indefinite period of time, such as
greater than 500 hours.
[0090] Alternatively, subsequent to arylhydroxy monomer removal by
vacuum distillation and/or steam sparging, the condensate is cooled
to temperatures less than 165.degree. C. and tested for melt
viscosity. If the viscosity is higher than the desired value, such
as about 1400 cps, a small amount of an additive also referred to
as a stabilizer (or diluent), of about 0.1 to about 2% relative to
the weight of the condensate may be added. The addition of
stabilizer helps control the viscosity of the resin from increasing
significantly when held at elevated temperatures for longer
duration during the solidification (flaking) process depending on
the size of the batch.
[0091] A further aspect for the low pKa acid method is to produce
the solid product described by any of the low pKa processes
described herein, and add a stabilizer or alternatively, to further
dissolve the product in one or more organic solvents having one or
more functionalities selected from the group of an ether
functionality, a ketone functionality, an alcohol functionality, an
ester functionality, and combinations thereof, of which methyl
ethyl ketone (MEK) is preferably used, and finish as a composition
preferably of from about 30 wt. % to about 60 wt. % solids.
The High pKa Acid Catalyst Method
[0092] In the processes described herein for making the condensate
for the high pKa value acid catalyst method, the pH of the mixture
of arylhydroxy monomer and acid catalyst may be from about 4 to
about 6.
[0093] In one embodiment of the high pKa acid catalyst method, the
initial reaction mixture includes an acid catalyst having a pKa
acidity of from greater than 6, such as a pKa acidity value from
greater than 6 to about 11, and the quantity of acid catalyst
varies from about 0.1% to about 1% by weight, such as from about
0.1 wt. % to about 0.5 wt. %, for example, from about 0.2 wt. % to
about 0.4 wt. % based on the quantity of arylhydroxy monomer
charged. Alternatively, if the acid catalyst is phenol or other
arylhydroxy corresponding to the arylhydroxy monomer, no additional
acidic catalyst may need to be added, and the reaction can be
considered as self-catalyzing.
[0094] Suitable acid catalysts that may be used in the high pKa
acid catalyst method include phenol, cresols, vanilla,
acetylacetone, glycine, cysteine, 2,3-dichlorophenol, hydroquinone,
chlorophenols, naphthols, nitrophenols, tryptophan, tyrosine,
xanthine, and combinations thereof, among others.
[0095] One embodiment of the process to form a condensate from
triazine monomers, arylhydroxy monomer, and aldehyde monomers
includes charging the triazine monomer to a reaction vessel,
charging from about 3 to about 30 moles, such as from about 9 to
about 14 moles, of an arylhydroxy monomer for each mole of triazine
monomer with about 0.1 wt. % to about 0.5 wt. % of the acid
catalyst described herein relative to the weight of the arylhydroxy
monomer. The acid catalyst may have a pKa of 6 to about 11, such as
a pKa acidity from about 9 to about 10. In one example, the
triazine monomer is melamine, the arylhydroxy monomer is phenol,
the aldehyde monomer is formaldehyde, and phenol itself with a pKa
of about 10 performs as the acid catalyst.
[0096] The reaction mixture is then heated at a temperature of
about 70.degree. C. to 110.degree. C. about 50% to 63% of the total
from about 1 mole to 6 moles, such as from about 2.2 moles to 3.2
moles (i.e., from about 1.1 to about 2.0 moles of the about moles
2.2 to 3.2 moles), of aldehyde monomer for each mole of triazine
monomer is then charged to the reaction vessel at this temperature.
Alternatively, the entire aldehyde monomer or compound containing
the aldehyde component, such as in HMMM described above may be
charged to the reaction vessel. The reaction mixture is then heated
to a temperature of about 130.degree. C. to about 160.degree. C. to
effect copolymerization of the three monomers and to remove water
and the temperature is maintained for about 1 to 2 hours.
[0097] The reaction mixture is then cooled to a temperature of
about 110.degree. C. or less, such as that of about 80.degree. C.
to 110.degree. C., and any remainder of the aldehyde monomer is
added. The reaction mixture is then heated to a temperature above
120.degree. C. to continue copolymerization and remove water and
the temperature is maintained for about 1 to about 2 hours until
the reaction of the arylhydroxy monomer is substantially
complete.
[0098] The reaction mixture is then heated to a temperature of
about 145.degree. C. to about 165.degree. C. to continue removing
water from the reaction mixture. The reaction mixture is then
distilled under full vacuum to remove most of the non-reacted
arylhydroxy monomer. Optionally, the reaction mixture may then be
further heated to further remove additional amounts of the
arylhydroxy monomer from the condensate, for example, to a
temperature not exceeding 180.degree. C. for phenol removal, when
steam sparging is adopted to remove trace amounts of the
arylhydroxy monomer from the condensate.
[0099] The recovered condensates were observed to have a range of
viscosity from about 500 cps to about 3000 cps, for example as from
about 1000 cps to about 1800 cps, containing from about 8 wt. % to
about 28 wt. % nitrogen content, for example, from greater than
about 10 wt. % to about 25 wt. % nitrogen content.
[0100] The recovered condensates exhibited a solubility in one or
more organic solvents having one or more functionalities selected
from the group of an ether functionality, a ketone functionality,
an alcohol functionality, an ester functionality, and combinations
thereof, of which methyl ethyl ketone (MEK) is preferably used,
from less than 10 wt. % solids to 80 wt. % solids (or higher), such
as from about 33 wt. % solids to about 75 wt. % solids to give a
transparent solution (no turbidity) that stayed dissolved for an
indefinite period of time, such as greater than 500 hours. For
example, the recovered condensates in the MEK solutions from about
33 wt. % solids to 80 wt. % and higher stayed dissolved for an
indefinite period of time, such as greater than 500 hours.
Alternatively, the High pKa Acid Method May be as Follows.
[0101] A second embodiment of the high pKa acid process to form a
condensate from triazine monomers, arylhydroxy monomers, and
aldehyde monomers includes charging the triazine monomer to a
reaction vessel, charging from about 3 to about 30 moles, such as
from about 9 to about 14 moles, of an arylhydroxy monomer for each
mole of triazine, to about 1 to about 6 moles, such as from about
2.2 to about 3.2 moles, of an aldehyde monomer for each mole of
triazine monomer with an optional amount from about 0.1 wt. % to
about 0.5 wt. % of the acid catalyst described herein relative to
arylhydroxy monomer weight. The acid catalyst may have a pKa of 6
to about 11. In one example, the triazine monomer is melamine, the
arylhydroxy monomer is phenol, the aldehyde monomer is
formaldehyde, and the arylhydroxy monomer is the acid catalyst.
[0102] The reaction mixture is then gradually heated from about
165.degree. C. to about 180.degree. C. in the distillation mode to
remove water and the arylhydroxy monomer. Steam sparging is
performed in the manner described earlier to remove last traces of
arylhydroxy monomer, and the product is obtained as a solid.
[0103] In a further alternative embodiment for the high pKa acid
method, the process may be as follows for the reaction of a
triazine derivative monomer and arylhydroxy monomer.
[0104] A third embodiment of the reaction to form a condensate
includes an aldehyde modified triazine monomer (an alkylated
methylol triazine) and arylhydroxy monomer being charged to a
reaction vessel, charging from about 3 to about 30 moles, such as
from about 9 to about 14 moles of an arylhydroxy monomer for each
mole of the aldehyde modified triazine monomer with an optional
amount from about 0.1 wt. % to about 0.5 wt. % of the acid catalyst
described herein relative to the weight of the arylhydroxy monomer.
The acid catalyst may have a pKa of greater than 6 to about 11. In
one example, the alkylated methylol triazine (for the triazine
monomer and aldehyde monomer) is hexamethoxymethylmelamine (HMMM),
the arylhydroxy monomer is phenol, and the arylhydroxy monomer is
the acid catalyst.
[0105] The reaction mixture is then gradually heated to from about
130.degree. C. to about 180.degree. C. in the distillation mode to
remove water and the arylhydroxy monomer. Steam sparging may then
be performed in the manner described earlier to remove last traces
of the arylhydroxy monomer. Then, applying a vacuum gradually until
most of non-reacted arylhydroxy monomer is removed at about
180.degree. C. to reduce the arylhydroxy monomer level to <2% in
the final product. The process is concluded by discharging the
product as a solid from the reaction vessel.
[0106] A fourth embodiment for the high pKa acid method is to
produce the solid product described by any of the processes
described herein for the high pKa acid method, and add a stabilizer
or alternatively, to further dissolve the product in one or more
organic solvents having one or more functionalities selected from
the group of an ether functionality, a ketone functionality, an
alcohol functionality, an ester functionality, and combinations
thereof, of which methyl ethyl ketone (MEK) is preferably used, and
finish the composition preferably as 30 wt. % to 60 wt. %
solids.
[0107] In both the low pKa acid catalyst method and the high pKa
acid catalyst method described herein, after the reaction mixture
is substantially free of the initial aldehyde monomer charge, the
reaction mixture is heated to a temperature and time sufficient to
prevent gelation of the reaction mixture such as on the subsequent
addition of the remaining aldehyde monomer. The time and
temperature for this can vary. Thus, in the case of the low pKa
acid catalyst method, gelation has been prevented by heating in the
presence of added acid at a temperature of about 100.degree. C. to
140.degree. C. for about one to four hours. In the case of the high
pKa acid catalyst method, gelation has been prevented by heating to
a temperature of about 130.degree. C. to 160.degree. C. for about
0.5 to 2.5 hours.
[0108] Without wishing to be held to any theory of operation, at
the lower temperatures of less than 100.degree. C., it appears that
the principal reaction is methylolation of the triazine with the
aldehyde. In such low temperature methylolation the arylhydroxy
monomer acts principally as a diluent in the reaction mixture and
as a solvent for the intermediate methylolated triazine. At higher
temperatures, for example, above about 110.degree. C., the
methylolated triazine or melamine condensate reacts with the
arylhydroxy monomer and phenolation takes place. Again not wishing
to he held to any theory of operation, the heating step, in those
methods where it is performed after the initial methylolation,
appears to cause rearrangement of the intermediate melamine
condensate, so as to free up methylene groups to react with the
arylhydroxy monomer as well as inhibiting gelation of an
intermediate condensate.
[0109] Additionally, the processes described herein involving the
acid catalysts allow for processing at temperatures not exceeding
180.degree. C. during the arylhydroxy monomer removal process and
by cooling the reaction mixture below 170.degree. C., thereby,
minimizing the condensate degradation. For example, a resin formed
from the condensate held at a temperature of 165.degree. C. for 7
hours exhibited lower viscosity growth and better solubility than
the resin held at 175.degree. C.
[0110] Since the arylhydroxy monomer (phenol) is charged in excess
to the reaction mixture, a substantial quantity of arylhydroxy
monomer, such as phenol, will be distilled out of the reaction
vessel after the substantially complete reaction of the arylhydroxy
monomer with the intermediate condensate and formation of the
triazine-arylhydroxy-aldehyde condensate as described herein. The
triazine-arylhydroxy-aldehyde condensate may then contain less than
about 2% by weight of arylhydroxy monomer. Steam sparging with or
without vacuum at such temperatures can also be used to remove
arylhydroxy monomer in the product, particularly to achieve free
phenol levels of about 2% or less by weight, such as arylhydroxy
monomer levels of less than 0.75% by weight.
[0111] Any water which has not been distilled is also removed from
the reaction mixture so that the product is substantially free of
water, for example less than about 1% by weight and preferably less
than about 0.5% by weight. Water may be removed from the reaction
mixture by distillation. Whatever water is not removed during such
distillations, may be removed after completion of the reactions at
temperatures of about 145.degree. C. to 165.degree. C. and whatever
water remains is removed when the excess arylhydroxy monomer i.e.,
free or non-reacted phenol, is removed from the reaction mixture by
conventional techniques such as that used for removal of
arylhydroxy monomer from other novolac resins such as by raising
the temperature from about 160.degree. C. to less than about
180.degree. C., such as up to about 175.degree. C., together with
increasing the vacuum to about 27 inches or above of mercury.
Epoxy Compositions Derived from Triazine-Arylhydroxy-Aldehyde
Condensates
[0112] The triazine-arylhydroxy-aldehyde condensates, as described
herein, may be curing agents for epoxy resins and as intermediates
in epoxy compositions, and also provide fire-retardant properties
to epoxy compositions. The compositions of the invention are
applicable for use with re-enforcement materials such as glass
cloth and fiber, thereby providing composites, for example,
laminates, for printed wire boards with superior properties. The
compositions as described herein are also suitable in the
manufacture of molded products as well as for other uses which
employ phenolic novolac resins.
The Epoxy Resin Compositions
[0113] The epoxy resin used in the processes and compositions
described herein may include one or more epoxy resins. The epoxy
resin compositions used in making the flame retardant compositions
and laminates as described herein will typically have weight per
epoxy equivalent (WPE) values of about 190 to about 10,000 and
preferably about 190 to about 500.
[0114] Illustrative of the epoxy resins, there may be mentioned
those of diglycidyl ether resins, such as those having the above
mentioned WPE values, prepared by contacting a dihydroxy compound
with an excess of epichlorohydrin in the presence of an alkali
metal hydroxide where the dihydroxy compound may be: bisphenol A,
brominated bisphenol A, bisphenol F, resorcinol, neopentyl glycol,
cyclohexanedimethanol, and combinations thereof. Such resins are
also referred to as being based on or derived from the dihydroxy
compound involved, for example bisphenol A. Glycidylated
triazine-arylhydroxy-aldehyde condensate may be made by known
methods, i.e., by reaction of the triazine-arylhydroxy-aldehyde
condensate with excess epihalohydrins, such as epichlorohydrin, in
the presence of an alkali. Isolation is preferably performed below
100.degree. C. as there may be a tendency to self-crosslink.
[0115] Also, such conventional epoxy resin may be that of: epoxy
phenol novolacs, epoxy cresol novolacs, particularly glycidyl
ethers of an o-cresol/formaldehyde novolacs, aromatic glycidyl
amine resins such as triglycidyl-p-amino phenol,
N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenyl methane, glycidyl
ethers of a phenolic novolac, poly(glycidylated) copolymers of
glycidyl methacrylate where the comonomer includes unsaturated
compounds such as acrylates, methacrylates and styrene, and
mixtures and co-polymers thereof, such as phenol-cresol novolac and
phenol-bisphenol A novolac co-polymers, of the various conventional
epoxy resins.
[0116] Non-glycidylated epoxy resins may also be employed. Examples
of such non-glycidylated epoxy resins include: limonene dioxide
(weight per epoxy of 85); vinyl cyclohexene dioxide; divinyl
benzene dioxide; 5-vinyl-2-norbornene dioxide (weight per epoxy of
76); 1,5-heptadiene dioxide; 1,7-octadiene dioxide. The
non-glycidylated epoxy compounds are preferably used in conjunction
with glycidylated epoxy resins and are also useful as diluents.
[0117] The reaction to form an epoxy resin composition with the
condensate described herein may be performed free of a curing
accelerator, such as an amine catalyst or a phosphorous containing
catalyst. If the epoxy resin composition is formed without the
presence of a curing accelerator, the epoxy resin composition may
be considered, or designated, as self-curing.
[0118] Epoxy curing accelerators may be used in the epoxy
compositions in a quantity sufficient to accelerate the cure of the
epoxy resin. Generally, such quantity may be from about 0.05 to 0.5
parts based on 100 parts of the base epoxy resin and particularly
about 0.1 to 0.2 parts. Curing accelerator, also referred to as
catalyst, may include amine catalysts. Such amine catalysts may
include, and are not limited to 2-methylimidazole,
2-ethyl-4-methylimidazole, amines such as
2,4,6-tris(dimethylaminomethyl)phenol and benzyldimethylamine, and
organophosphorus compounds such as tributylphosphine and
triphenylphosphine. A separate curing accelerator may not need to
be used to form the epoxy resins/compositions; and the epoxy
component and the triazine-arylhydroxy-aldehyde condensate may
comprise a self-catalyzing formulation.
[0119] Compositions as described herein when used in electronic
applications such as laminates for the production of printed
circuit boards will typically comprise the following composition
based on 100 parts of an epoxy resin: (a) about 0-30 parts of
phenolic-formaldehyde novolac; (b) about 30-60 parts of the
triazine-arylhydroxy-aldehyde condensates as described herein; and
(c) optionally, an epoxy curing accelerator.
[0120] The triazine-arylhydroxy-aldehyde condensate may be used as
the curing agent alone and/or to impart flame-retardant properties
to the epoxy resin. Alternatively, the
triazine-arylhydroxy-aldehyde condensate may be used together with
one or more conventional epoxy resin curing agents and/or
flame-retardant agents.
[0121] A variety of curing agents well known in the art may be used
together with the triazine-arylhydroxy-aldehyde condensates as
described herein in curing the epoxy resin. The curing agents
include and are not limited to aromatic amines, polyamidoamines,
polyamides; dicyandiamide, phenolic-formaldehyde novolacs,
melamine-formaldehyde resins, melamine-phenolic-formaldehyde
resins, benzoguanamine-phenolic-formaldehyde resins and
combinations thereof. Examples of suitable curing agents of a
phenolic-formaldehyde novolac curing agent include compounds
selected from the group of phenol novolac, cresol novolac, naphthol
novolac, bisphenol A novolac, phenol-glyoxal condensate, and
combinations and subsets thereof.
[0122] Reactive diluents for the epoxy compositions may also be
present in the epoxy compositions to lower viscosity and improve
handling characteristics. Examples of reactive diluents include
neopentylglycol diglycidyl ether, butanediol diglycidyl ether,
resorcinol diglycidyl ether, cyclohexane dimethanol diglycidyl
ether, and combinations thereof.
[0123] When phenolic novolacs are used as curing agents, a catalyst
(accelerator) is generally employed and may be selected from
tertiary organic amines such as 2-alkylimidazoles,
benzyldimethylamine, and phosphines such as triphenylphosphine, and
combinations thereof.
[0124] The phenolic novolac curing agents are condensation products
of a phenol with an aldehyde or ketone, and the phenolic monomer
may be selected from phenol itself, cresols, xylenols, resorcinol,
bisphenol-A, paraphenyl phenol, naphthol, and combinations and
subsets thereof. Substituents for the phenolic monomers include
hydroxy, alkyl of 1 to 4 carbon atoms, alkoxy of 1 to 4 carbon
atoms as well as phenyl. Particularly preferred curing agents are
the phenol-formaldehyde novolacs, for example, where the phenol is
phenol itself, and ortho-cresol-formaldehyde novolacs having a
molecular weight of 600 to 5,000 and preferably about 1,000 to
5,000. Illustrative of the aldehydes for preparation of the
phenolic novolac curing agents there may be mentioned formaldehyde,
acetaldehyde, benzaldehyde and hydroxybenzaldehyde. Illustrative of
ketones for preparation of the phenolic novolac curing agents there
may be mentioned acetone, hydroxyacetophenone, and methyl ethyl
ketone.
[0125] A wide variety of solvents may be used in the epoxy
compositions as described herein including one or more organic
solvents having one or more functionalities selected from the group
of an ether functionality, a ketone functionality, an alcohol
functionality, an ester functionality, and combinations thereof.
Suitable solvents include halogenated solvents, ketone solvents,
alcohol solvents, ether solvents including glycol ethers, ester
solvents, such as glycol ester solvents including glycol acetates,
N,N-dimethylformamide, or combinations thereof, may be used in the
epoxy compositions. The latter is particularly useful when
dicyandiamide is used as curing agent. Ketones include acetone,
methyl ethyl ketone, diethyl ketone, and methyl isobutyl
ketone.
[0126] Phosphorus containing additives may be used for enhancing
the flame retardants properties of the epoxy formulations with the
triazine-arylhydroxy-aldehyde condensates described herein.
Examples of suitable phosphorus containing additives include
elemental red phosphorus, phosphorus and phosphoric acids,
triphenyl phosphine, triphenyl phosphine oxide, cyclic and linear
phosphazines such as various phenoxyphosphazene compounds,
tris(2-hydroxyphenyl)-phosphine oxide,
9,10-dihydro-9-oxa-10(2,5-dioxotetrahydro-3-furanylmethyl)-10-phosphphaph-
e nanthrene-10-oxide, melamine phosphate, melamine cyanurate,
non-halogenated phosphorus compounds in U.S. Pat. No. 3,702,878,
U.S. Pat. No. 5,481,017, U.S. Pat. No. 4,086,206, and
bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite (Ultranox 626
by GE Specialty Chemicals of Parkersburg, W. Va.) The quantity of
the phosphorus containing additive can vary from about one percent
to ten percent based on the weight of the triazine monomers, phenol
monomers, and aldehyde monomers additive.
Laminates of the Epoxy Resin Compositions
[0127] The laminates as described herein are conventional laminates
containing a reinforcing agent such as glass cloth, and a cured
resinous matrix comprising an epoxy resin and a
triazine-arylhydroxy-aldehyde condensate as described herein as a
curing agent and flame-retardant alone or together with other
curing agents and/or flame retardant agents for the epoxy resin.
The laminates may comprise the reinforcing agent together with the
cured epoxy compositions mentioned hereinabove.
[0128] The structure of the laminates as described herein are the
same as those of conventional laminates containing a reinforcing
agent such as glass cloth, and a resinous matrix comprising an
epoxy resin and a curing agent for the epoxy resin.
[0129] The laminates as described herein will generally contain
about 40% to 80% by weight of resinous matrix material to about 20%
to 60% by weight of reinforcing material such as glass cloth.
[0130] Conventional laminating techniques may be used in making the
laminates as described herein such as the wet or dry-lay-up
techniques. Multiple layers of resin impregnated reinforcing
material, upon curing, make up the laminate.
[0131] The pressure used in making the laminates can vary from the
contact pressure of applying a laminated lining to a tank wall to
the high pressure, for example, 1,000 psi or more, used in the
manufacture of electrical insulation sheets. The temperature used
in making the laminates can vary over a wide range such as that of
about room temperature to over 210.degree. C.
[0132] The laminate may be prepared at room temperature or by
heating under pressure a layer comprising at least one sheet of
prepreg comprising an epoxy resin as impregnate. The pressure used
in making the laminates can vary from the contact pressure of
applying a laminated lining to a tank wall to the high pressure,
for example, 1,000 psi or more, used in the manufacture of
electrical insulation sheets. The temperature used in making the
laminates can vary over a wide range such as that of about room
temperature to over 210.degree. C. The use of a solvent in the
laminate compositions is optional. Conventional laminating
techniques may be used in making the laminates as described herein,
for example, such as the wet or dry-lay-up techniques.
[0133] Reinforcing fibers or fabrics of reinforcing fibers for use
in laminates include glass fibers and mats, carbon and graphite
fibers, cellulosic paper, fibrous polyamide sheets, fibrous quartz
sheets, woven fibrous glass cloth, unwoven fibrous glass mat, and
the like. The epoxy resin composition will be impregnated in the
reinforcing fibers or fabrics or the interstices formed from such
fibers or fabrics. Fillers such as quartz powdered, mica, talc,
calcium carbonate and the like may also be added to the resinous
matrix in the manufacture of the laminate.
EXAMPLES
[0134] In order that those skilled in the art may more fully
understand the invention presented herein, the following procedures
and examples are set forth. Unless otherwise indicated, the
following units of measurement and definitions apply in this
application: all parts and percentages are by weight; temperatures
are in degrees centigrade (.degree. C.); and readings of vacuum are
in inches of mercury.
[0135] For the following examples, the data was derived in
accordance with the following procedures.
[0136] The weight average molecular weight (Mw) and number average
molecular weight (Mn) herein are measured using size exclusion gel
permeation chromatography (SEC) and phenolic compounds and
polystyrene standards. The sample molecular weight to be measured
is prepared as follows: the sample is dissolved in tetrahydrofuran
and the solution is run through a gel permeation chromatograph. Any
free phenolic in the sample is excluded from the calculation of
molecular weight. SEC as a measure of molecular weight is highly
dependant on the hydrodynamic volume of the material in solvent.
Highly branched or polycyclic materials tend to give lower values
than molecular weights determined by other means such as vapor
phase osmometry (VPO).
[0137] The nitrogen content of the condensate is determined based
on the moles of aldehyde (formaldehyde) and arylhydroxy (phenol)
monomer incorporated for every mole of triazine (melamine). While
the moles of aldehyde is the initial amount charged, amount of
arylhydroxy monomer incorporated is obtained by subtracting the
amount of non-reacted arylhydroxy monomer removed as vacuum
distillate from the amount initially charged.
[0138] In this calculation, any excess arylhydroxy monomer above 2%
is included as a part of non-reacted monomer. For the sake of
consistency, the weight of arylhydroxy monomer incorporated is its
molecular weight-1 (that is 94-1=93 for phenol) to allow loss of
one hydrogen atom because of its bonding with the aldehyde.
Similarly, for the triazine monomer, such as melamine, the weight
incorporated is its molecular weight minus the number of moles of
aldehyde tied to every mole of triazine. For example, 126-3 (if
there are 3 moles of formaldehyde for every mole of melamine)=123
will be the contribution from melamine to the molecular weight of
the condensate.
[0139] A closer look at Example 5 illustrates the method of
calculation. The initial mole ratio of F to M is 3.0. Phenol
incorporated or reacted (P.sub.R) in the product for every mole of
melamine is obtained as follows: {(593.5 g-417.8 g)/94.1}/0.6=3.11
where 593.5 g is the initial phenol charge, 417.8 g is the amount
of phenol monomer removed and 0.6 is the total of moles of melamine
charged. Therefore, the final mole ratio M:F:P.sub.R=1:3.0:3.11.
This amounts to a molecular mass of 123+(3*14)+(3.11*93)=454 where
14 is the molecular weight of methylene bridge that links melamine
and phenol monomer. Therefore, nitrogen content in the condensate
is 84/454*100=18.5 wt. % where 84 is simply the atomic weight of
nitrogen multiplied by 6 as there are 6 moles of nitrogen per mole
of melamine.
[0140] Determination of solubility in organic solvents, such as
methyl ethyl ketone (MEK) may be described as follows. An organic
solvent may have one or more functionalities selected from the
group of an ether functionality, a ketone functionality, an alcohol
functionality, an ester functionality, and combinations thereof,
for example, a ketone solvent, an alcohol solvent, an ether
solvent, a glycol ether solvent, an ester solvent, a glycol ester
solvent, and combinations thereof, of which methyl ethyl ketone
(MEK) is preferably used, among other solvents that are used in
epoxy formulations. Suitable solvents may include methyl ethyl
ketone (MEK), methyl isobutyl ketone (MIBK), acetone, methanol,
isopropyl alcohol, 1 methoxy-2-propanol, and combinations
thereof.
[0141] A 4-dram glass vial is charged with 1.5 g of powdered
triazine-arylhydroxy-aldehyde condensate made by the processes
described herein. To which is added various amounts of methyl ethyl
ketone (MEK) to give solutions with different concentration. The
table below gives the amounts of MEK to be added to 1.5 g of
condensate to yield the desired solids level.
TABLE-US-00001 MEK, g wt. % solids 13.5 10 3 33 2.25 40 1.5 50 1 60
0.65 70 0.38 80
[0142] For concentrations of 33% or below, the vial is capped and
contents mixed at ambient temperature for 5 to 10 minutes until
resin dissolves completely or no further dissolution occurs. For
concentrations greater than 33% the vial is capped, sealed with
insulation tape and heated in 60.degree. C. to 70.degree. C. oven
until most of the resin is dissolved. The sample vial is then taken
out and optionally mixed for 5 to 10 minutes until resin dissolves
completely or no further dissolution occurs. The solubility of the
condensate in MEK is noted. The vial is then allowed to sit at
ambient temperature of between about 20.degree. C. and about
25.degree. C., and observations are made on a daily basis.
[0143] For concentrations of 33 wt. % solids or higher, the
following criteria are applied to further differentiate the
solubility between different resins. It is not unusual for such
solutions to develop cloudiness (a stage when the solution would
not allow seeing through) over time which may eventually lead to a
solid circle of white coating at the bottom. It is either in the
rate at which this cloudiness/precipitation occurs or if such
phenomena occur at all that differentiates one resin to the other
in terms of their solubility.
[0144] A triazine-arylhydroxy-aldehyde condensate is observed to
exhibit excellent solubility if dissolved in an organic solvent up
to 75% solids, and in some embodiments may be greater than 75%
solids, such as 80 wt. % solids, and may stay dissolved for at
least 120 hours before cloudiness sets in or precipitation begins
in the form of flocculent or white circle at the bottom of the
vial. For example, a condensate of 33 wt. % solids in a solvent was
observed to remain dissolved for at least 120 hours before
cloudiness sets in or precipitation begins in the form of
flocculent or white circle at the bottom of the vial.
[0145] A triazine-arylhydroxy-aldehyde condensate is observed to
exhibit superior solubility if dissolved in an organic solvent up
to 75% solids, and in some embodiments may be greater than 75%
solids, such as 80 wt. % solids, and may stay dissolved for at
least 500 hours before cloudiness sets in or precipitation begins
in the form of flocculent or white circle at the bottom of the
vial. For example, a condensate of 33 wt. % solids in a solvent was
observed to remain dissolved for at least 500 hours before
cloudiness sets in or precipitation begins in the form of
flocculent or white circle at the bottom of the vial.
[0146] Triazine-arylhydroxy-aldehyde condensates prepared by the
high pKa process typically exhibit superior solubility, if
dissolved in an organic solvent, with up to 75% solids, and in some
embodiments may be greater than 75% solids, such as 80 wt. %
solids, and may stay dissolved for at least 500 hours before
cloudiness sets in or precipitation begins. For example, a
triazine-arylhydroxy-aldehyde condensate of 33 wt. % solids in a
solvent was observed to remain dissolved for at least 500 hours
before cloudiness sets in or precipitation begins.
[0147] Triazine-arylhydroxy-aldehyde condensates prepared by the
low pKa process typically exhibit excellent solubility, if
dissolved in an organic solvent, with up to 75% solids, and in some
embodiments may be greater than 75% solids, such as 80 wt. %
solids, and may stay dissolved for at least 120 hours before
cloudiness sets in or precipitation begins. For example, a
triazine-arylhydroxy-aldehyde condensate of 33 wt. % solids in a
solvent remained dissolved for at least 120 hours before cloudiness
sets in or precipitation begins. In fact, many of these resins also
exhibit superior solubility in spite of being held at 165.degree.
C. during production for long hours.
Determination of Melt Viscosities
[0148] Viscosities, at 175.degree. C., were determined with a cone
and plate viscometer from Research Equipment (London) Ltd. Number
40 and 100 spindles were used depending on the viscosity reading. A
factor multiplier of 340 was used for the Number 40 spindle and a
factor multiplier of 965 was used for the of 100 spindle values
shown from digital readout. For example, a digital reading of 5
obtained with a #40 cone spindle would be multiplied by 340 to give
a viscosity value of 1700 cps. Viscosities were also determined
using ARES Rheometer from Rheometric Scientific. Viscosities were
measured at 150.degree. C.-200.degree. C. using a parallel plate
assembly at 1% strain with 2.degree. C. per minute heating. The
viscosity thus measured is reported in mPas (1 mPas=1 cps).
[0149] Comparisons were made between resins made by prior
technology using the high basicity amine catalyst method and high
temperature acid catalyst method as described in the U.S. Pat. No.
6,605,354 against those made by low pKa and high pKa processes
described in this invention. For example, resins made by current
invention dissolved even up to 80 wt. % solids in MEK. Whereas, the
resin made by the high temperature acid catalyst method of prior
art gave a cloudy liquid with insoluble precipitates even at 40 wt.
% solids level. Also, while resins made by current invention stayed
dissolved in MEK at 33 wt. % solids from a minimum of 120 hours to
indefinite period of time, resins made by prior art turned cloudy
and precipitated in the form of a circle at the bottom of the vial
within 24 hours to 96 hours.
[0150] Examples of condensates formed from the components and
processes described herein are as follows.
Example 1
Preparation of Melamine-Phenol-Formaldehyde Condensate
[0151] The process for Example 1 was initiated by charging 546.0
grams (g) phenol (5.80 moles), 1.1 g benzoic acid (0.2% of phenol),
and 79.1 g melamine (0.63 moles) into a reaction vessel to form a
reaction mixture. The reaction mixture was heated to 80.degree. C.,
and 55.8 g of 50.4% aqueous formaldehyde (60% of total charge) was
added over 40 minutes. The reaction mixture was atmospherically
distilled while heating to 123.degree. C., and then maintaining the
123.degree. C. temperature for 2 hours, followed by reducing the
reaction mixture temperature to 80.degree. C. 37.2 g of 50.4%
aqueous formaldehyde (40% of total charge) was added over 30
minutes to the reaction mixture and then atmospherically distilling
the reaction mixture to 123.degree. C., maintaining the temperature
at 123.degree. C. for 1.5 hours, and increasing the temperature
over 45-50 minutes to 165.degree. C. and continuing to distill
atmospherically. Next, the reaction mixture was under a gradually
increasing vacuum over 3 hours to a full vacuum of at least 27
inches while maintaining a temperature of 163.degree.-165.degree.
C., then heating the reaction mixture to 175.degree. C. over 1 hour
under full vacuum, followed by maintaining the vacuum and
temperature at 175.degree. C. for 15 minutes, and then steaming the
reaction mixture (or water sparge) at 175.degree. C. for 60
minutes, and after 60 minutes, cooling the resin to
164.degree.-167.degree. C. in about 15 minutes. Further, the
process was concluded by removing the vacuum distillate (426.6 g)
and discharging the product (212.9 g) from the reaction vessel.
[0152] In this instance, no stabilizer was added as the melt
viscosity of the resin was 1333 cps at 175.degree. C. The
condensate dissolved completely in MEK, acetone, THF, methanol and
Dowanol PM at almost any concentration. The 33 wt. % to 60 wt. %
solids remained dissolved in MEK with only trace at the bottom for
instance for more than 240 hours. The 70 wt. % and 80 wt. % solids
remained dissolved in MEK indefinitely.
Example 2
Preparation of Melamine-Phenol-Formaldehyde Condensate
[0153] The process for Example 2 was initiated by charging 828.0
lbs phenol (8.8 moles), 1.66 lbs benzoic acid (0.2% of phenol), and
120 lbs melamine (0.95 moles) into a reaction vessel to form a
reaction mixture. The reaction mixture was heated to 80.degree. C.,
and 85.4 lbs of 49.79% aqueous formaldehyde (60% of total charge)
was added over 40 minutes. The reaction mixture was atmospherically
distilled while increasing the temperature of the reaction mixture
to 123.degree. C., then maintaining the 123.degree. C. temperature
for 2 hours before reducing the reaction mixture temperature to
80.degree. C. 57.2 lbs of 49.79% aqueous formaldehyde (40% of total
charge) was added in over 30 minutes to the reaction mixture,
followed by atmospherically distilled to 123.degree. C., maintained
at the temperature of 123.degree. C. for 1.5 hours, and then
increasing the temperature over 45-50 minutes to 165.degree. C. and
continuing to distill atmospherically. Next, the reaction mixture
was under a gradually increasing vacuum over 3 hours to full vacuum
of at least 27 inches while maintaining a temperature of
163.degree.-165.degree. C., followed by heating the reaction
mixture to 175.degree. C. over 1 hour under full vacuum, then
maintaining the vacuum and temperature at 175.degree. C. for 15
minutes before steaming the reaction mixture (or water sparge) at
175.degree. C. for 60 minutes, and after 60 minutes cooling the
resin to 164.degree.-167.degree. C. in about 15 minutes.
[0154] In this instance, the melt viscosity of the resin was 1983
cps at 175.degree. C. About 3.2 lbs each of ortho and para cresol
was added to the resin. The resin was held in the reactor for about
9 hours at 165.degree. C. Further, the process was concluded by
collecting the vacuum distillate (634 lbs) and discharging the
product (318 lbs) from the reactor assembly. The condensate
exhibited solubility similar to that of example 1. For instance,
the 33 wt. % solids dissolved readily in MEK and remained dissolved
for greater than 500 hours.
Example 3
Preparation of Melamine-Phenol-Formaldehyde Condensate
[0155] The process for Example 3 is initiated by charging 221.5 g
phenol (2.35 moles), 31.9 g melamine (0.25 moles), 36.6 g of 50%
formaldehyde (0.61 moles) into a reaction vessel to form a reaction
mixture, heating the reaction mixture under distillation mode until
distillation starts around 115-120.degree. C., gradually increasing
the temperature up to about 170.degree. C. while water and phenol
are removed atmospherically. Then, applying a vacuum gradually
until most of non-reacted phenol is removed, and water sparging the
reaction mixture at about 180.degree. C. to reduce the phenol level
to <1% in the final product. The process is concluded by
removing phenol (172 g) distillate and discharging the product
(87.3 g) from the reaction vessel. The recovered product exhibited
a solubility of almost any concentration such as from 33 wt. %
solids to 70 wt. % solids in common solvents such as MEK. Such
solutions remained dissolved in a MEK for greater than 500 hours or
indefinitely without precipitation.
Example 4
Preparation of Melamine-Phenol-Formaldehyde Condensate
[0156] The process for Example 4 was initiated by charging 593.5 g
phenol (6.31 moles) and 75.2 g melamine (0.60 moles) into a
reaction vessel to form a reaction mixture. The reaction mixture
was heated to 80.degree. C., and 53.14 g of 50.15% aqueous
formaldehyde (60% of total charge) was added over 15 minutes. The
reaction mixture was atmospherically distilled to 133.degree. C.,
then maintained at 133.degree. C. temperature for 2 hours, followed
by reducing the reaction mixture temperature to 80.degree. C. 35.45
g of 50.15% aqueous formaldehyde (40% of total charge) was added in
about 20 minutes to the reaction mixture, then atmospherically
distilling the reaction mixture to 133.degree. C., maintained at
133.degree. C. for 1.3 hours, and then increasing the temperature
over 60 minutes to 165.degree. C. while continuing to distill
atmospherically. Next, the reaction mixture was under a gradually
increasing vacuum over 2 hours to full vacuum of at least 27 inches
while maintaining a temperature of 163.degree.-165.degree. C., and
then heating the reaction mixture to 175.degree. C. under full
vacuum. Further, the process is concluded by removing the vacuum
distillate (439.7 g) and discharging the product (236.7 g) from the
reaction vessel. The condensate exhibited a solubility of 33% and
higher solids dissolved in a solvent for 120 hours or greater.
Example 5
Preparation of Melamine-Phenol-Formaldehyde Condensate
[0157] The process for Example 5 was initiated by charging 593.5 g
phenol (6.31 moles), 4.3 g of acetic acid (0.72% of phenol) and
75.2 g melamine (0.60 moles) into a reaction vessel to form a
reaction mixture. The reaction mixture was heated to 80.degree. C.,
and 64.1 g of 50.3% aqueous formaldehyde (60% of total charge) was
added in over 20 minutes. The reaction mixture went under
atmospherically distilling to 123.degree. C., then maintained at
123.degree. C. for 2 hours followed by reducing the reaction
mixture temperature to 80.degree. C. 42.5 g of 50.3% aqueous
formaldehyde (40% of total charge) was added over about 20 minutes
to the reaction mixture, followed by atmospherically distilling the
reaction mixture to 123.degree. C., then maintaining the
temperature at 123.degree. C. for 1.6 hours, and finally increasing
the temperature over 60 minutes to 165.degree. C. and continuing to
distill atmospherically. Next, the reaction mixture was under a
gradually increasing vacuum over 2 hours to full vacuum of at least
27 inches while maintaining a temperature of
163.degree.-165.degree. C., and then heating the reaction mixture
to 175.degree. C. under full vacuum. Further, the process is
concluded by removing the vacuum distillate (417.8 g) and
discharging the product (263.0 g) from the reaction vessel.
[0158] Similar to Example 3, the recovered product exhibited a
solubility of almost any concentration such as from 33 wt. % solids
to 70 wt. % solids in common solvents mentioned earlier such as
MEK. For example, the condensate exhibited a solubility of 33% and
higher solids dissolved in MEK for greater than 500 hours or
indefinitely.
Example 6
Preparation of Melamine-Phenol-Formaldehyde Condensate
[0159] The process for Example 6 was initiated by charging 593.5 g
phenol (6.31 moles), 1.2 g of benzoic acid (0.2% of phenol) and
75.2 g melamine (0.60 moles) into a reaction vessel to form a
reaction mixture. The reaction mixture was heated to 80.degree. C.
and 64.1 g of 50.3% aqueous formaldehyde (60% of total charge) was
added over 26 minutes. The reaction mixture was atmospherically
distilled to 123.degree. C., maintained at 123.degree. C. for 2
hours, and then reduced to 80.degree. C. 42.5 g of 50.3% aqueous
formaldehyde (40% of total charge) was added over about 17 minutes
to the reaction mixture, and then atmospherically distilled to
123.degree. C., and then maintaining the temperature at 123.degree.
C. for 1.4 hours followed by increasing the temperature over 50
minutes to 165.degree. C. and continuing to distill
atmospherically. Next, the reaction mixture was under a gradually
increasing vacuum over 2 hours to full vacuum of at least 27 inches
while maintaining a temperature of 163.degree.-165.degree. C.,
followed by heating the reaction mixture to 175.degree. C. under
full vacuum. Further, the process is concluded by removing the
vacuum distillate (413.7 g) and discharging the product (261.2 g)
from the reaction vessel.
[0160] Similar to example 3, the recovered product exhibited a
solubility of almost any concentration such as from 33 wt. % solids
to 70 wt. % solids in common solvents mentioned earlier such as
MEK. For example, the condensate exhibited a solubility of 33% and
higher solids dissolved in MEK beyond 500 hours or
indefinitely.
Example 7
Preparation of Melamine-Phenol-Formaldehyde Condensate
[0161] The process for Example 7 was initiated by charging 593.4 g
phenol (6.31 moles) and 0.86 g of triethylamine into a reaction
vessel to form a reaction mixture. The reaction mixture was heated
to 75.degree. C., and 75.6 g melamine (0.60 moles) was added and
mixed for 15 minutes. 53.81 g of 50.17% aqueous formaldehyde (50%
of total charge) was added over 30 minutes. 53.61 g of 50.17%
aqueous formaldehyde (50% of total charge) was added over 32
minutes. The reaction mixture was maintained at 75.degree. C. for 2
hours and then heated to 85.degree. C. before maintaining the
temperature for 30 minutes. The reaction mixture was
atmospherically distilled to 110.degree. C. and the temperature was
maintained at 110.degree. C. for 3 hours, before reducing the
reaction mixture temperature to 100.degree. C. under reflux mode.
4.21 g of benzoic acid slowly over 10 minutes was added and mixed
for over 5 minutes. The reaction mixture was then atmospherically
distilled to 110.degree. C. and the temperature maintained at
110.degree. C. for 2 hours. The reaction mixture was then
atmospherically distilled to 150.degree. C. and the temperature
maintained at 150.degree. C. for 2 hours before increasing the
temperature to 165.degree. C. while continuing to distill
atmospherically. Next, the reaction mixture was under a gradually
increasing vacuum over 1.5 hours to full vacuum of at least 27
inches while maintaining a temperature of 163.degree.-165.degree.
C. before heating the reaction mixture to 175.degree. C. under full
vacuum. Further, the process was concluded by discharging the
product (293.6 g) and the vacuum distillate (383.4 g) from the
reaction vessel.
[0162] The condensate exhibited solubility in variety of common
solvents described herein. Particularly, the 33% solids in MEK
solution remained clear with only a trace for greater than 408
hours and the 75% solids in MEK remained clear for greater than 500
hours or indefinitely.
Example 8
Preparation of Melamine-Phenol-Formaldehyde Condensate
[0163] The process for Example 8 was initiated by charging 593.5 g
phenol (6.31 moles), 1.2 g of benzoic acid (0.2% of phenol) and
75.2 g melamine (0.60 moles) into a reaction vessel to form a
reaction mixture. The reaction mixture was heated to 80.degree. C.
and 68.7 g of 50.1% aqueous formaldehyde (60% of total charge) was
added in over 30 minutes. The reaction mixture was atmospherically
distilled to 123.degree. C., and then maintaining the 123.degree.
C. temperature for 2 hours before reducing the reaction mixture
temperature to 80.degree. C. 45.8 g of 50.1% aqueous formaldehyde
(40% of total charge) was added over about 15 minutes to the
reaction mixture, followed by atmospherically distilling the
reaction mixture to 123.degree. C., maintaining the temperature at
123.degree. C. for 1.5 hours, and then increasing the temperature
over 50 minutes to 165.degree. C. and continuing to distill
atmospherically. Next, the reaction mixture was under a gradually
increasing vacuum over 2 hours to full vacuum of at least 27 inches
while maintaining a temperature of 163.degree.-165.degree. C.
before heating the reaction mixture to 175.degree. C. under full
vacuum. Further, the process is concluded by removing the vacuum
distillate (395.0 g) and discharging the product (279.2 g) from the
reaction vessel.
[0164] The product exhibited superior solubility in most solvents.
For example the 33% and higher solids remained dissolved in MEK
beyond 500 hours and indefinitely.
Example 9A
Preparation of HMMM-Phenol-Condensate
[0165] The process for Example 9A is initiated by charging 49.2 g
of HMMM (0.126 moles), 162.8 g phenol (1.73 moles) into a reaction
vessel to form a reaction mixture, heating the reaction mixture
under distillation mode until distillation starts around
155-160.degree. C., gradually increasing the temperature up to
about 180.degree. C. while water and phenol are removed
atmospherically. Then applying a vacuum gradually until most of
non-reacted phenol is removed at about 180.degree. C. to reduce the
phenol level to <2% in the final product. The process is
concluded by removing the vacuum distillate (129.0 g) and
discharging the product (55.8 g) from the reaction vessel. The
recovered product was found to dissolve readily at 33 wt. % to 70
wt. % solids dissolved in a solvent such as MEK and was observed to
remain dissolved in MEK solution for 500 hours or indefinitely
without precipitation. This composition is believed to be a
self-curing condensate composition.
[0166] The following Example 9B is a comparative example of a prior
art process for forming a condensate that illustrates the reduced
solubility using a strong acid in comparison to the improved
solubility of a process using a acid catalyst having a pKa value of
greater than 3.8. The prior art reaction shown in the following
Example 9B involves the use of a strong sulfonic acid, phenol, and
HMMM. The strong sulfonic acid, such as methane sulfonic acid (MSA)
catalyst, has a negative pKa value of -2.0.
Example 9B
Preparation of HMMM-Phenol-Condensate
[0167] The process for Example 9B is initiated by charging 99.9 g
of HMMM (0.256 moles), 326.9 g phenol (3.47 moles), 3.6 g of MSA
into a reaction vessel to form a reaction mixture, heating the
reaction mixture under distillation mode until distillation starts
around 110.degree. C., gradually increasing the temperature up to
about 180.degree. C. while water and phenol are removed
atmospherically. Then, applying a vacuum gradually until most of
non-reacted phenol is removed at about 200.degree. C. to reduce the
phenol level to <1% in the final product. The process is
concluded by removing the vacuum distillate (about 167.9 g) and
discharging the product (220 g) from the reaction vessel. The
recovered product was found to dissolve at 33 wt. % solids in MEK
and was observed to remain dissolved for less than 120 hours before
which the solutions turned cloudy with significant precipitate
floating at the bottom of the vial.
Example 10
Preparation of HMMM-p-Cresol-Condensate
[0168] The process for Example 10 is initiated by charging 182.2 g
of HMMM (0.47 moles), 298.7 g p-cresol (2.76 moles) into a reaction
vessel to form a reaction mixture, heating the reaction mixture
under distillation mode until distillation starts around
139.degree. C., gradually increasing the temperature up to about
175.degree. C. while methanol is removed atmospherically. Then,
applying vacuum gradually and increasing the temperature to about
185.degree. C. until most of non-reacted p-cresol is removed in the
final product. The process is concluded by removing atmospheric and
vacuum distillate (102.8 g, which includes about 90.2 g methanol)
and discharging the product (364.7 g) from the reaction vessel.
[0169] The condensate was found to exhibit self-curing like
behavior as evident from significant viscosity increase when held
at 175.degree. C. for longer duration. The condensate was found to
dissolve readily even at 33% for 120 hours as well as 60 wt. %
solids indefinitely in MEK without precipitation. Although the 60%
wt. % solids was trace-free, whereas the 33% had a small trace at
the bottom.
[0170] EXAMPLE 11A and 11B are a comparative example of a prior art
process compared with a process for forming a condensate as
described herein.
[0171] Preparation of Melamine-Phenol-Formaldehyde (MPF) Condensate
Based on U.S. Pat. No. 6,605,354.
[0172] This process is the manufacturing example 29 in the patent,
except that the M:F mole ratio was kept at 2.7 instead of 3 and
non-reacted phenol was distilled at 175.degree. C. instead of
190.degree. C.
[0173] In the comparative Example 11A, a process includes charging
593.5 g phenol (6.307 moles), 1.2 g oxalic acid (first pKa value of
1.2; 0.2% of phenol), and 75.2 g melamine (0.597 moles) into a
reaction vessel to form a reaction mixture. The reaction mixture
was then heated to 80.degree. C. and 57.9 g of 50.16% aqueous
formaldehyde was added over in 24 minutes. The reaction mixture was
atmospherically distilled to 123.degree. C., maintained at
123.degree. C. temperature for 2 hours, and then the reaction
mixture temperature was reduced to 80.degree. C. 38.6 g of 50.16%
aqueous formaldehyde was added over 20 minutes to the reaction
mixture and then atmospherically distilled to 123.degree. C., then
maintaining the temperature at 123.degree. C. for 1.5 hours, and
followed by increasing the temperature over 45-50 minutes to
165.degree. C. and continuing to distill atmospherically. Next, the
reaction mixture was under a gradually increasing vacuum over 2
hours to full vacuum of 29 inches while maintaining a temperature
of 163.degree.-165.degree. C., and then heating the reaction
mixture to 175.degree. C. over 1 hour under full vacuum. Further,
discharging the product (246.8 g) and the vacuum distillate (423.0
g) from the reaction vessel.
[0174] The condensate exhibited poor solubility in MEK. It formed a
cloudy solution in the beginning, which resulted in white insoluble
precipitate that settled at the bottom within a few hours. A TPA
condensate is described as having a poor solubility if it does not
completely dissolve even at 33% or less solids in an organic
solvent and may leave a thick white precipitate at the bottom
instantly.
[0175] In comparison Example 11B, a condensate from a process
described herein includes charging 593.5 g phenol (6.307 moles),
1.2 g benzoic acid (pKa value of 4.2; 0.2% of phenol), and 75.2 g
melamine (0.597 moles) into a reaction vessel to form a reaction
mixture. The reaction mixture was heated to 80.degree. C., and 57.9
g of 50.16% aqueous formaldehyde was added over 24 minutes. Then,
the reaction mixture was atmospherically distilled mixture to
123.degree. C., then maintained at 123.degree. C. temperature for 2
hours followed by reducing the reaction mixture temperature to
80.degree. C. 38.6 g of 50.16% aqueous formaldehyde was added over
20 minutes to the reaction mixture followed by atmospherically
distilling the reaction mixture to 123.degree. C., maintaining the
temperature at 123.degree. C. for 1.5 hours, and increasing the
temperature over 45-50 minutes to 165.degree. C. and continue to
distill atmospherically. Next, the reaction mixture was under a
gradually increasing vacuum over 2 hours to frill vacuum of 29
inches while maintaining a temperature of 163.degree.-165.degree.
C., heating the reaction mixture to 175.degree. C. over 1 hour
under full vacuum. Further, discharging the product (244.0 g) and
the vacuum distillate (428.0 g) from the reaction vessel.
[0176] The condensate exhibited superior solubility in MEK. The
condensate remained soluble for an indefinite period of time.
[0177] The properties of the resins in examples 1-11B are given
below in Table 1.
[0178] Table I: Properties of triazine-phenol-aldehyde condensates
are summarized below:
TABLE-US-00002 TABLE I Melt Viscosity at Arylhydroxy Mw/ Nitrogen
Example 175.degree. C., cps monomer, % Mw Mn Mn calcd. % 1 1365
0.75 448 315 1.42 24.3 2 1560 0.48 472 327 1.44 23.1 3 2602* 0.84
622 375 1.66 23.7 4 1037 0.29 417 308 1.35 20.5 5 1966 ND 533 353
1.51 18.5 6 1740 0.69 552 363 1.52 18.5 7 340 0.52 467 317 1.48
16.5 8 1966 0.76 601 382 1.57 17.0 9A 1788, 1938* 1.90 1097 511
2.15 17.9 9B 1040, 935* 0.57 607 326 1.56 10.3 Com- parative
Example 10 1003 3.0** 1845 651 2.84 10.4 11A 1674 0.81 475 340 1.40
19.1 Com- parative Example 11B 2178 0.15 500 347 1.44 19.2 Com-
parative Example- current invention *mPa s; ND = None Detected;
**Obtained by SEC while others were obtained by Gas
Chromatograph
[0179] The processes described herein were scaled up to pilot plant
size batches, and the following data was generated indicating that
the processes described herein had effective scalability from
laboratory scale to plant scale. The results of three pilot batches
are given below in Tables II and Tables III. Entries Number 1 and 2
are formed using the process in Example 2, with different heating
times. Entry number 3 is formed by the process as recited in
Example 1.
TABLE-US-00003 TABLE II Hours remained Entry Hours held Melt
viscosity, dissolved for 33% Number at 165 C. Phenol, % cps solids
and above 1 12.3 0.64 1560 528 2 16.8 0.67 1560 120 to 144 3 4.7
0.77 1333 >504
TABLE-US-00004 TABLE III Melt % Increase viscosity in viscosity
Melt viscosity Hours held of the from the Entry after phenol at 165
C. final resin, time of phenol Number removal, cps after removal
cps removal to final 1 1333 9 1560 17 2 1430 12 1560 9
[0180] Thus stability of these resins are clearly elucidated by
these pilot scale-ups, where in the viscosity increase during
processing is less than 20% in one case and less than 10% in the
other while the solubility rating in MEK was Superior for entry #1
and entry #3 with less heat history and Excellent for entry #2 with
longer heating time.
[0181] While the present invention has been described and
illustrated by reference to particular embodiments and examples,
those of ordinary skill in the art will appreciate that the
invention lends itself to variations not necessarily illustrated
herein. For this reason, then, reference should be made solely to
the appended claims for purposes of determining the true scope of
the present invention.
* * * * *