U.S. patent application number 10/947265 was filed with the patent office on 2006-07-27 for flame-retardant thermoset composition, method, and article.
This patent application is currently assigned to General Electric Company. Invention is credited to John Robert Campbell, Bryan Duffey, John Austin Rude, Prameela Susarla, Michael Alan Vallance, Gary Williams Yeager, Kenneth Paul Zarnoch.
Application Number | 20060167142 10/947265 |
Document ID | / |
Family ID | 34393937 |
Filed Date | 2006-07-27 |
United States Patent
Application |
20060167142 |
Kind Code |
A9 |
Campbell; John Robert ; et
al. |
July 27, 2006 |
FLAME-RETARDANT THERMOSET COMPOSITION, METHOD, AND ARTICLE
Abstract
A curable composition includes a functionalized poly(arylene
ether) resin, an acryloyl monomer, and a phosphorus flame
retardant. The composition exhibits an improved balance of
properties such as toughness, flame retardance, heat-resistance,
and moisture resistance. It is useful, for example, as an
encapsulant for semiconductor products.
Inventors: |
Campbell; John Robert;
(Clifton Park, NY) ; Duffey; Bryan; (Ballston Spa,
NY) ; Rude; John Austin; (Ballston Lake, NY) ;
Susarla; Prameela; (Clifton Park, NY) ; Vallance;
Michael Alan; (Loudonville, NY) ; Yeager; Gary
Williams; (Rexford, NY) ; Zarnoch; Kenneth Paul;
(Scotia, NY) |
Correspondence
Address: |
GENERAL ELECTRIC COMPANY;GLOBAL RESEARCH
PATENT DOCKET RM. BLDG. K1-4A59
NISKAYUNA
NY
12309
US
|
Assignee: |
General Electric Company
|
Prior
Publication: |
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Document Identifier |
Publication Date |
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US 20050075427 A1 |
April 7, 2005 |
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Family ID: |
34393937 |
Appl. No.: |
10/947265 |
Filed: |
September 23, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10678471 |
Oct 3, 2003 |
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10947265 |
Sep 23, 2004 |
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10188181 |
Jul 2, 2002 |
6812276 |
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10947265 |
Sep 23, 2004 |
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09683214 |
Dec 3, 2001 |
6905637 |
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10947265 |
Sep 23, 2004 |
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Current U.S.
Class: |
524/115 |
Current CPC
Class: |
C08L 51/08 20130101;
C08K 5/5313 20130101; C08L 2201/02 20130101; C08F 283/08 20130101;
C08G 65/48 20130101; C08K 5/5313 20130101; C08L 71/126 20130101;
C08F 290/062 20130101; C08G 65/485 20130101 |
Class at
Publication: |
524/115 |
International
Class: |
C08K 5/49 20060101
C08K005/49 |
Claims
1. A curable composition, comprising: a functionalized poly(arylene
ether) resin; an acryloyl monomer; and a phosphorus flame retardant
having the formula ##STR25## wherein M.sup.d+ is a metal ion or an
onium ion; d is 1, 2, 3, or 4 according to the identity of M and
its oxidation state; each occurrence of R.sup.23 and R.sup.24 is
independently C.sub.1-C.sub.18 hydrocarbyl; and each occurrence of
m and n is 0 or 1.
2. The composition of claim 1, wherein the functionalized
poly(arylene ether) resin is a capped poly(arylene ether) resin
having the formula Q(J-K).sub.y wherein Q is the residuum of a
monohydric, dihydric, or polyhydric phenol; y is 1 to 100; J
comprises repeating structural units having the formula ##STR26##
wherein R.sup.1 and R.sup.3 are each independently selected from
the group consisting of hydrogen, halogen, primary or secondary
C.sub.1-C.sub.12 alkyl, C.sub.2-C.sub.12 alkenyl, C.sub.2-C.sub.12
alkynyl, C.sub.1-C.sub.12 aminoalkyl, C.sub.1-C.sub.12
hydroxyalkyl, phenyl, C.sub.1-C.sub.12 haloalkyl, C.sub.1-C.sub.12
hydrocarbyloxy, and C.sub.2-C.sub.12 halohydrocarbyloxy wherein at
least two carbon atoms separate the halogen and oxygen atoms;
R.sup.2 and R.sup.4 are each independently selected from the group
consisting of halogen, primary or secondary C.sub.1-C.sub.12 alkyl,
C.sub.2-C.sub.12 alkenyl, C.sub.2-C.sub.12 alkynyl,
C.sub.1-C.sub.12 aminoalkyl, C.sub.1-C.sub.12 hydroxyalkyl, phenyl,
C.sub.1-C.sub.12 haloalkyl, C.sub.1-C.sub.12 hydrocarbyloxy, and
C.sub.2-C.sub.12 halohydrocarbyloxy wherein at least two carbon
atoms separate the halogen and oxygen atoms; m is 1 to about 200;
and K is a capping group selected from the group consisting of
##STR27## wherein R.sup.5 is C.sub.1-C.sub.12 alkyl;
R.sup.6-R.sup.8 are each independently selected from the group
consisting of hydrogen, C.sub.1-C.sub.18 hydrocarbyl,
C.sub.2-C.sub.18 hydrocarbyloxycarbonyl, nitrile, formyl,
carboxylate, imidate, and thiocarboxylate; R.sup.9-R.sup.13 are
each independently selected from the group consisting of hydrogen,
halogen, C.sub.1-C.sub.12 alkyl, hydroxy, and amino; and wherein Y
is a divalent group selected from the group consisting of ##STR28##
wherein R.sup.14 and R.sup.15 are each independently selected from
the group consisting of hydrogen and C.sub.1-C.sub.12 alkyl.
3. The curable composition of claim 2, wherein Q is the residuum of
a monohydric phenol.
4. The curable composition of claim 1, wherein the capped
poly(arylene ether) comprises at least one capping group having the
structure ##STR29## wherein R.sup.6-R.sup.8 are each independently
selected from the group consisting of hydrogen, C.sub.1-C.sub.18
hydrocarbyl, C.sub.2-C.sub.12 hydrocarbyloxycarbonyl, nitrile,
formyl, carboxylate, imidate, and thiocarboxylate.
5. The curable composition of claim 4, wherein R.sup.6 is hydrogen
or methyl, and R.sup.7 and R.sup.8 are hydrogen.
6. The curable composition of claim 1, comprising about 5 to about
90 parts by weight of the functionalized poly(arylene ether) per
100 parts by weight total of the functionalized poly(arylene ether)
and the acryloyl monomer.
7. The composition of claim 1, wherein the acryloyl monomer
comprises at least one acryloyl moiety having the structure
##STR30## wherein R.sup.18 and R.sup.19 are each independently
selected from the group consisting of hydrogen and C.sub.1-C.sub.12
alkyl, and wherein R.sup.18 and R.sup.19 may be disposed either cis
or trans about the carbon-carbon double bond.
8. The composition of claim 1, wherein the acryloyl monomer
comprises at least one acryloyl moiety having the structure
##STR31## wherein R.sup.20-R.sup.22 are each independently selected
from the group consisting of hydrogen, C.sub.1-C.sub.12
hydrocarbyl, C.sub.2-C.sub.18 hydrocarbyloxycarbonyl, nitrile,
formyl, carboxylate, imidate, and thiocarboxylate.
9. The composition of claim 8, wherein the acryloyl monomer
comprises at least two acryloyl moieties.
10. The composition of claim 8, wherein the acryloyl monomer
comprises at least three acryloyl moieties.
11. The composition of claim 1, wherein the acryloyl monomer is
selected from trimethylolpropane tri(meth)acrylate, 1,6-hexanediol
di(meth)acrylate, neopentyl glycol di(meth)acrylate, ethylene
glycol di(meth)acrylate, propylene glycol di(meth)acrylate,
cyclohexanedimethanol di(meth)acrylate, butanediol
di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene
glycol di(meth)acrylate, isobornyl (meth)acrylate, methyl
(meth)acrylate, methacryloxypropyl trimethoxysilane, ethoxylated
(2) bisphenol A di(meth)acrylate, 4-biphenyl (meth)acrylate,
4,4'-biphenol di(meth)acrylate, and mixtures thereof.
12. The composition of claim 1, comprising about 10 to about 95
parts acryloyl monomer per 100 parts by weight total of the
functionalized poly(arylene ether) and the acryloyl monomer.
13. The composition of claim 1, wherein each occurrence of R.sup.23
and R.sup.24 is independently C.sub.1-C.sub.6 alkyl.
14. The composition of claim 1, wherein each occurrence of R.sup.23
and R.sup.24 is methyl or ethyl.
15. The composition of claim 1, wherein M is aluminum and each
occurrence of m and n is zero.
16. The composition of claim 1, wherein the phosphorus flame
retardant is aluminum tris(diethylphosphinate).
17. The composition of claim 1, comprising about 0.1 to about 50
parts by weight of the phosphorus flame retardant per 100 parts by
weight total of the functionalized poly(arylene ether) and the
acryloyl monomer.
18. The composition of claim 1, further comprising an aromatic
bisphosphoramidate flame retardant of the formula ##STR32## wherein
A is a monocyclic aromatic radical and D.sup.1 is a C.sub.1-4
primary or secondary alkyl radical or both D.sup.1 radicals taken
together are ethylene.
19. The composition of claim 1, further comprising an aromatic
polyphosphate flame retardant having the formula ##STR33## wherein
each occurrence of R.sup.6-R.sup.8 is independently selected from
the group consisting of hydrogen, C.sub.1-C.sub.18 hydrocarbyl,
C.sub.2-C.sub.12 hydrocarbyloxycarbonyl, nitrile, formyl,
carboxylate, imidate, and thiocarboxylate; r is 2 to about 20; and
each occurrence of s is 0, 1, or 2, with the proviso that at least
one occurrence of s is 1.
20. The curable composition of claim 1, further comprising a
nitrogen-containing flame retardant selected from triazines,
guanidines, cyanurates, isocyanurates, ammonium polyphosphates, and
mixtures thereof.
21. The curable composition of claim 20, wherein the
nitrogen-containing flame retardant comprises a melamine
polyphosphate represented by the formula ##STR34## wherein g has an
average value of about 3 to about 10,000, and the ratio of f to g
is about 0.5:1 to about 1.7:1.
22. The composition of claim 1, further comprising an alkenyl
aromatic compound having the formula ##STR35## wherein each
occurrence of R.sup.16 is independently hydrogen or
C.sub.1-C.sub.18 hydrocarbyl; each occurrence of R.sup.17 is
independently halogen, C.sub.1-C.sub.12 alkyl, C.sub.1-C.sub.12
alkoxyl, or C.sub.6-C.sub.18 aryl; p is 1 to 4; and q is 0 to
5.
23. The curable composition of claim 22, wherein the alkenyl
aromatic monomer is selected from styrene, .alpha.-methylstyrene,
2-methylstyrene, 3-methylstyrene, 4-methylstyrene,
2-t-butylstyrene, 3-t-butylstyrene, 4-t-butylstyrene,
1,3-divinylbenzene, 1,4-divinylbenzene, 1,3-diisopropenylbenzene,
1,4-diisopropenylbenzene, styrenes having from 1 to 5 halogen
substituents on the aromatic ring, and combinations thereof.
24. The composition of claim 22, comprising about 10 to about 500
parts by weight alkenyl aromatic monomer per 100 parts by weight
total of the functionalized poly(arylene ether) and the acryloyl
monomer.
25. The composition of claim 1, further comprising an allylic
monomer.
26. The composition of claim 25, wherein the allylic monomer is
selected from diallyl phthalate, diallyl isophthalate, triallyl
mellitate, triallyl mesate, triallyl benzenes, triallyl cyanurate,
triallyl isocyanurate, and mixtures thereof.
27. The composition of claim 25, comprising about 10 to about 500
parts by weight allylic monomer per 100 parts by weight total of
the functionalized poly(arylene ether) and the acryloyl
monomer.
28. The curable composition of claim 1, further comprising about 5
to about 95 weight percent of a particulate filler, based on the
total weight of the composition.
29. The curable composition of claim 28, wherein the particulate
filler is fused silica.
30. The curable composition of claim 28, wherein the particulate
filler comprises a first fused silica having an average particle
size of about 0.03 micrometer to less than 1 micrometer, and a
second fused silica having an average particle size greater than 1
micrometer to about 30 micrometers.
31. The curable composition of claim 1, further comprising a curing
catalyst.
32. The curable composition of claim 31, wherein the curing
catalyst is selected from benzoyl peroxide, dicumyl peroxide,
methyl ethyl ketone peroxide, lauryl peroxide, cyclohexanone
peroxide, t-butyl hydroperoxide, t-butyl benzene hydroperoxide,
t-butyl peroctoate, 2,5-dimethylhexane-2,5-dihydroperoxide,
2,5-dimethyl-2,5-di(t-butylperoxy)-hex-3-yne, di-t-butylperoxide,
t-butylcumyl peroxide,
.alpha.,.alpha.'-bis(t-butylperoxy-m-isopropyl)benzene,
2,5-dimethyl-2,5-di(t-butylperoxy)hexane, di(t-butylperoxy)
isophthalate, t-butylperoxybenzoate, 2,2-bis(t-butylperoxy)butane,
2,2-bis(t-butylperoxy)octane,
2,5-dimethyl-2,5-di(benzoylperoxy)hexane,
di(trimethylsilyl)peroxide, trimethylsilylphenyltriphenylsilyl
peroxide, and mixtures thereof.
33. The curable composition of claim 1, further comprising a curing
inhibitor.
34. The curable composition of claim 33, wherein the curing
inhibitor is selected from diazoaminobenzene, phenylacetylene,
sym-trinitrobenzene, p-benzoquinone, acetaldehyde, aniline
condensates, N,N'-dibutyl-o-phenylenediamine,
N-butyl-p-aminophenol, 2,4,6-triphenylphenoxyl, pyrogallol,
catechol, hydroquinone, C.sub.1-C.sub.6-alkyl-substituted
catechols, dialkylhydroquinone, 2,4,6-dichloronitrophenol,
halogen-ortho-nitrophenols, alkoxyhydroquinone, mono- and di- and
polysulfides of phenols and catechols, thiols and oximes and
hydrazones of quinone, phenothiazine, dialkylhydroxylamines, and
combinations thereof.
35. The curable composition of claim 1, further comprising an
additive selected from dyes, pigments, colorants, antioxidants,
heat stabilizers, light stabilizers, plasticizers, lubricants, flow
modifiers, drip retardants, flame retardants, antiblocking agents,
antistatic agents, flow-promoting agents, processing aids,
substrate adhesion agents, mold release agents, toughening agents,
low-profile additives, stress-relief additives, and combinations
thereof.
36. A curable composition, comprising: a (meth)acrylate-capped
poly(2,6-dimethyl-1,4-phenylene ether) resin, a
(meth)acrylate-capped poly(2,6-dimethyl-1,4-phenylene
ether-co-2,3,6-trimethyl-1,4-phenylene ether) resin, or a mixture
thereof; an acryloyl monomer selected from trimethylolpropane
tri(meth)acrylate, hexanediol di(meth)acrylate,
cyclohexanedimethanol di(meth)acrylate, methacryloxypropyl
trimethoxysilane, ethoxylated (2) bisphenol A dimethacrylate,
4-biphenyl (meth)acrylate, 4,4'-biphenol di(meth)acrylate, and
mixtures thereof; an aluminophosphorus flame retardant having the
formula ##STR36## wherein each occurrence of R.sup.23 and R.sup.24
is independently C.sub.1-C.sub.6 alkyl, and each occurrence of m
and n is 0; a melamine polyphosphate represented by the formula
##STR37## wherein g has an average value of about 3 to about
10,000, and the ratio of f to g is about 0.5:1 to about 1.7:1; and
fused silica.
37. A cured composition, comprising the reaction product obtained
by curing the curable composition of claim 36.
38. A curable composition, comprising: about 5 to about 40 parts by
weight of a (meth)acrylate-capped poly(2,6-dimethyl-1,4-phenylene
ether) resin, a (meth)acrylate-capped
poly(2,6-dimethyl-1,4-phenylene
ether-co-2,3,6-trimethyl-1,4-phenylene ether) resin, or a mixture
thereof; about 60 to about 95 parts by weight of an acryloyl
monomer selected from trimethylolpropane tri(meth)acrylate,
hexanediol di(meth)acrylate, cyclohexanedimethanol
di(meth)acrylate, methacryloxypropyl trimethoxysilane, ethoxylated
(2) bisphenol A di(meth)acrylate, 4-biphenyl (meth)acrylate,
4,4'-biphenol di(meth)acrylate, and mixtures thereof; about 1 to
about 50 parts by weight of aluminum tris(diethylphosphinate); and
about 0.1 to about 5 parts by weight of a melamine polyphosphate;
about 100 to about 2,000 parts by weight of fused silica; wherein
all parts by weight are based on 100 parts by weight total for the
(meth)acrylate-capped poly(arylene ether) resin and the acryloyl
monomer.
39. A cured composition, comprising the reaction product obtained
by curing the curable composition of claim 38.
40. A cured composition, comprising the reaction product obtained
by curing the curable composition of claim 1.
41. The cured composition of claim 40, having a UL94 rating of V-0
or V-1 at a thickness of 1 to 10 millimeters.
42. The cured composition of claim 40, having a glass transition
temperature of at least 120.degree. C.
43. The cured composition of claim 40, wherein the composition
dried for 24 hours at 115.degree. C. exhibits a weight difference
less than .+-.0.05% after exposure to 168 hours at 85.degree. C.
and 85% relative humidity and redrying for 24 hours at 115.degree.
C.
44. An article comprising the cured composition of claim 37.
45. An article comprising the cured composition of claim 39.
46. An article comprising the cured composition of claim 40.
47. A method of preparing a curable composition, comprising:
blending a functionalized poly(arylene ether) resin; an acryloyl
monomer; and a phosphorus flame retardant having the formula
##STR38## wherein M.sup.d+ is a metal ion or an onium ion; d is 1,
2, 3, or 4 according to the identity of M and its oxidation state;
each occurrence of R.sup.23 and R.sup.24 is independently
C.sub.1-C.sub.18 hydrocarbyl; and each occurrence of m and n is 0
or 11 to form an intimate blend.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of U.S.
application Ser. No. 10/678,471 filed Oct. 3, 2003.
BACKGROUND OF THE INVENTION
[0002] Curable compositions are often used to encapsulate
electronic components. These encapsulating materials must be
self-extinguishing in the case of ignition. Commercially available
compositions for encapsulation typically employ a combination of
halogenated aromatic compounds and antimony oxides to achieve flame
retardance. However, the halogenated aromatic compounds interfere
with the recycling of electronic devices, and concerns have been
raised about health effects associated with antimony oxides. There
is therefore a need for flame-retardant encapsulant compositions
that reduce or eliminate halogenated aromatic compounds and
antimony oxides while maintaining or improving the balance of
toughness, heat resistance, and moisture resistance.
BRIEF DESCRIPTION OF THE INVENTION
[0003] One embodiment is a curable composition, comprising: a
functionalized poly(arylene ether) resin; an acryloyl monomer; and
a phosphorus flame retardant having the formula ##STR1## wherein
M.sup.d+ is a metal ion or an onium ion; d is 1, 2, 3, or 4
according to the identity of M and its oxidation state; each
occurrence of R.sup.23 and R.sup.24 is independently
C.sub.1-C.sub.18 hydrocarbyl; and each occurrence of m and n is 0
or 1.
[0004] Other embodiments, including filled curable compositions,
cured compositions, and articles comprising the cured compositions,
are described in detail below.
DETAILED DESCRIPTION OF THE INVENTION
[0005] The present inventors have found that excellent flame
retardance, heat resistance, moisture resistance, and toughness are
exhibited by a cured composition comprising the cured product of: a
functionalized poly(arylene ether) resin; an acryloyl monomer; and
a phosphorus flame retardant having the formula ##STR2## wherein
M.sup.d+ is a metal ion or an onium ion; d is 1, 2, 3, or 4
according to the identity of M and its oxidation state; each
occurrence of R.sup.23 and R.sup.24 is independently
C.sub.1-C.sub.18 hydrocarbyl; and each occurrence of m and n is 0
or 11.
[0006] The functionalized poly(arylene ether) may be a capped
poly(arylene ether), a ring-functionalized poly(arylene ether), or
an acid- or anhydride-functionalized poly(arylene ether). A capped
poly(arylene ether) is defined herein as a poly(arylene ether) in
which at least 50%, preferably at least 75%, more preferably at
least 90%, yet more preferably at least 95%, even more preferably
at least 99%, of the free hydroxyl groups present in the
corresponding uncapped poly(arylene ether) have been functionalized
by reaction with a capping agent.
[0007] The capped poly(arylene ether) may be represented by the
structure Q(J-K).sub.y wherein Q is the residuum of a monohydric,
dihydric, or polyhydric phenol, preferably the residuum of a
monohydric or dihydric phenol, more preferably the residuum of a
monohydric phenol; y is 1 to 100; J comprises repeating structural
units having the formula ##STR3## wherein m is 1 to about 200,
preferably 2 to about 200, and R.sup.1 and R.sup.3 are each
independently hydrogen, halogen, primary or secondary
C.sub.1-C.sub.12 alkyl, C.sub.2-C.sub.12 alkenyl, C.sub.2-C.sub.12
alkynyl, C.sub.1-C.sub.12 aminoalkyl, C.sub.1-C.sub.12
hydroxyalkyl, phenyl, C.sub.1-C.sub.12 haloalkyl, C.sub.1-C.sub.12
hydrocarbyloxy, C.sub.2-C.sub.12 halohydrocarbyloxy wherein at
least two carbon atoms separate the halogen and oxygen atoms, or
the like; R.sup.2 and R.sup.4 are each independently halogen,
primary or secondary C.sub.1-C.sub.12 alkyl, C.sub.2-C.sub.12
alkenyl, C.sub.2-C.sub.12 alkynyl, C.sub.1-C.sub.12 aminoalkyl,
C.sub.1-C.sub.12 hydroxyalkyl, phenyl, C.sub.1-C.sub.12 haloalkyl,
C.sub.1-C.sub.12 hydrocarbyloxy, C.sub.2-C.sub.12
halohydrocarbyloxy wherein at least two carbon atoms separate the
halogen and oxygen atoms, or the like; and K is a capping group
produced by reaction of a phenolic hydroxyl group on the
poly(arylene ether) with a capping agent. The resulting capping
group may be ##STR4## or the like, wherein R.sup.5 is
C.sub.1-C.sub.12 alkyl, or the like; R.sup.6-R.sup.8 are each
independently hydrogen, C.sub.1-C.sub.18 hydrocarbyl,
C.sub.2-C.sub.18 hydrocarbyloxycarbonyl, nitrile, formyl,
carboxylate, imidate, thiocarboxylate, or the like;
R.sup.9-R.sup.13 are each independently hydrogen, halogen,
C.sub.1-C.sub.12 alkyl, hydroxy, amino, or the like; and wherein Y
is a divalent group such as ##STR5## or the like, wherein R.sup.14
and R.sup.15 are each independently hydrogen, C.sub.1-C.sub.12
alkyl, or the like. As used herein, "hydrocarbyl" refers to a
residue that contains only carbon and hydrogen. The residue may be
aliphatic or aromatic, straight-chain, cyclic, bicyclic, branched,
saturated, or unsaturated. The hydrocarbyl residue, when so stated
however, may contain heteroatoms over and above the carbon and
hydrogen members of the substituent residue. Thus, when
specifically noted as containing such heteroatoms, the hydrocarbyl
residue may also contain carbonyl groups, amino groups, hydroxyl
groups, or the like, or it may contain heteroatoms within the
backbone of the hydrocarbyl residue.
[0008] In one embodiment, Q is the residuum of a phenol, including
polyfunctional phenols, and includes radicals of the structure
##STR6## wherein R.sup.1 and R.sup.3 are each independently
hydrogen, halogen, primary or secondary C.sub.1-C.sub.12 alkyl,
C.sub.2-C.sub.12 alkenyl, C.sub.2-C.sub.12 alkynyl,
C.sub.1-C.sub.12 aminoalkyl, C.sub.1-C.sub.12 hydroxyalkyl, phenyl,
C.sub.1-C.sub.12 haloalkyl, C.sub.1-C.sub.12 aminoalkyl,
C.sub.1-C.sub.12 hydrocarbyloxy, C.sub.1-C.sub.12
halohydrocarbyloxy wherein at least two carbon atoms separate the
halogen and oxygen atoms, or the like; R.sup.2 and R.sup.4 are each
independently halogen, primary or secondary C.sub.1-C.sub.12 alkyl,
C.sub.2-C.sub.12 alkenyl, C.sub.2-C.sub.12 alkynyl,
C.sub.1-C.sub.12 aminoalkyl, C.sub.1-C.sub.12 hydroxyalkyl, phenyl,
C.sub.1-C.sub.12 haloalkyl, C.sub.1-C.sub.12 aminoalkyl,
C.sub.1-C.sub.12 hydrocarbyloxy, C.sub.1-C.sub.12
halohydrocarbyloxy wherein at least two carbon atoms separate the
halogen and oxygen atoms, or the like; X may be hydrogen,
C.sub.1-C.sub.18 hydrocarbyl, or C.sub.1-C.sub.18 hydrocarbyl
containing a substituent such as carboxylic acid, aldehyde,
alcohol, amino radicals, or the like; X also may be sulfur,
sulfonyl, sulfuryl, oxygen, or other such bridging group having a
valence of 2 or greater to result in various bis- or higher
polyphenols; n (i.e., the number of phenylene ether units bound to
X) is 1 to about 100, preferably 1 to 3, and more preferably 1 to
2. Q may be the residuum of a monohydric phenol, such as
2,6-dimethylphenol, in which case n is 1. Q may also be the
residuum of a diphenol, such as
2,2',6,6'-tetramethyl-4,4'-diphenol, in which case n is 2.
[0009] In one embodiment, the capped poly(arylene ether) is
produced by capping a poly(arylene ether) consisting essentially of
the polymerization product of at least one monohydric phenol having
the structure ##STR7## wherein R.sup.1 and R.sup.3 are each
independently hydrogen, halogen, primary or secondary
C.sub.1-C.sub.12 alkyl, C.sub.2-C.sub.12 alkenyl, C.sub.2-C.sub.12
alkynyl, C.sub.1-C.sub.12 aminoalkyl, C.sub.1-C.sub.12
hydroxyalkyl, phenyl, C.sub.1-C.sub.12 haloalkyl, C.sub.1-C.sub.12
aminoalkyl, C.sub.1-C.sub.12 hydrocarbyloxy, C.sub.1-C.sub.12
halohydrocarbyloxy wherein at least two carbon atoms separate the
halogen and oxygen atoms, or the like; and R.sup.2 and R.sup.4 are
each independently halogen, primary or secondary C.sub.1-C.sub.12
alkyl, C.sub.2-C.sub.12 alkenyl, C.sub.2-C.sub.12 alkynyl,
C.sub.1-C.sub.12 aminoalkyl, C.sub.1-C.sub.12 hydroxyalkyl, phenyl,
C.sub.1-C.sub.12 haloalkyl, C.sub.1-C.sub.12 aminoalkyl,
C.sub.1-C.sub.12 hydrocarbyloxy, C.sub.1-C.sub.12
halohydrocarbyloxy wherein at least two carbon atoms separate the
halogen and oxygen atoms, or the like. Suitable monohydric phenols
include those described in U.S. Pat. No. 3,306,875 to Hay, and
highly preferred monohydric phenols include 2,6-dimethylphenol and
2,3,6-trimethylphenol. The poly(arylene ether) may be a copolymer
of at least two monohydric phenols, such as 2,6-dimethylphenol and
2,3,6-trimethylphenol.
[0010] In one embodiment, the capped poly(arylene ether) comprises
at least one capping group having the structure ##STR8## wherein
R.sup.6-R.sup.8 are each independently hydrogen, C.sub.1-C.sub.18
hydrocarbyl, C.sub.2-C.sub.18 hydrocarbyloxycarbonyl, nitrile,
formyl, carboxylate, imidate, thiocarboxylate, or the like. Highly
preferred capping groups include acrylate
(R.sup.6=R.sup.7=R.sup.8=hydrogen) and methacrylate
(R.sup.6=methyl, R.sup.7=R.sup.8=hydrogen). It will be understood
that the term "(meth)acrylate" means either acrylate or
methacrylate.
[0011] In another embodiment, the capped poly(arylene ether)
comprises at least one capping group having the structure ##STR9##
wherein R.sup.5 is C.sub.1-C.sub.12 alkyl, preferably
C.sub.1-C.sub.6 alkyl, more preferably methyl, ethyl, or isopropyl.
The advantageous properties of the invention can be achieved even
when the capped poly(arylene ether) lacks a polymerizable function
such as a carbon-carbon double bond.
[0012] In yet another embodiment, the capped poly(arylene ether)
comprises at least one capping group having the structure ##STR10##
wherein R.sup.9-R.sup.13 are each independently hydrogen, halogen,
C.sub.1-C.sub.12 alkyl, hydroxy, amino, or the like. Preferred
capping groups of this type include salicylate (R.sup.9=hydroxy,
R.sup.10-R.sup.13=hydrogen).
[0013] In still another embodiment, the capped poly(arylene ether)
comprises at least one capping group having the structure ##STR11##
wherein A is a saturated or unsaturated C.sub.2-C.sub.12 divalent
hydrocarbon group such as, for example, ethylene, 1,2-propylene,
1,3-propylene, 2-methyl-1,3-propylene, 2,2-dimethyl-1,3-propylene,
1,2-butylene, 1,3-butylene, 1,4-butylene, 2-methyl-1,4-butylene,
2,2-dimethyl-1,4-butylene, 2,3-dimethyl-1,4-butylene, vinylene
(--CH.dbd.CH--), 1,2-phenylene, and the like. These capped
poly(arylene ether) resins may conveniently be prepared, for
example, by reaction of an uncapped poly(arylene ether) with a
cyclic anhydride capping agent. Such cyclic anhydride capping
agents include, for example, maleic anhydride, succinic anhydride,
glutaric anhydride, adipic anhydride, phthalic anhydride, and the
like.
[0014] There is no particular limitation on the method by which the
capped poly(arylene ether) is prepared. The capped poly(arylene
ether) may be formed by the reaction of an uncapped poly(arylene
ether) with a capping agent. Capping agents include compounds known
in the literature to react with phenolic groups. Such compounds
include both monomers and polymers containing, for example,
anhydride, acid chloride, epoxy, carbonate, ester, isocyanate,
cyanate ester, or alkyl halide radicals. Capping agents are not
limited to organic compounds as, for example, phosphorus and sulfur
based capping agents also are included. Examples of capping agents
include, for example, acetic anhydride, succinic anhydride, maleic
anhydride, salicylic anhydride, polyesters comprising salicylate
units, homopolyesters of salicylic acid, acrylic anhydride,
methacrylic anhydride, glycidyl acrylate, glycidyl methacrylate,
acetyl chloride, benzoyl chloride, diphenyl carbonates such as
di(4-nitrophenyl)carbonate, acryloyl esters, methacryloyl esters,
acetyl esters, phenylisocyanate,
3-isopropenyl-.alpha.,.alpha.-dimethylphenylisocyanate,
cyanatobenzene, 2,2-bis(4-cyanatophenyl)propane,
3-(.alpha.-chloromethyl)styrene, 4-(.alpha.-chloromethyl)styrene,
allyl bromide, and the like, and substituted derivatives thereof,
and mixtures thereof. These and other methods of forming capped
poly(arylene ether)s are described, for example, in U.S. Pat. Nos.
3,375,228 to Holoch et al.; 4,148,843 to Goossens; 4,562,243,
4,663,402, 4,665,137, and 5,091,480 to Percec et al.; 5,071,922,
5,079,268, 5,304,600, and 5,310,820 to Nelissen et al.; 5,338,796
to Vianello et al.; U.S. Patent Application Publication No.
2001/0053820 A1 to Yeager et al.; and European Patent No. 261,574
B1 to Peters et al.
[0015] In a preferred embodiment, the curable composition further
comprises an alkenyl aromatic monomer, and the capped poly(arylene
ether) is be prepared by reaction of an uncapped poly(arylene
ether) with an anhydride in the alkenyl aromatic monomer as
solvent. This approach has the advantage of generating the capped
poly(arylene ether) in a form that can be immediately blended with
other components to form a curable composition. Using this method,
no isolation of the capped poly(arylene ether) or removal of
unwanted solvents or reagents is required.
[0016] A capping catalyst may be employed in the reaction of an
uncapped poly(arylene ether) with an anhydride. Examples of such
compounds include those known to the art that are capable of
catalyzing condensation of phenols with the capping agents
described above. Useful materials include, but are not limited to,
basic compounds including, for example, basic compound hydroxide
salts such as sodium hydroxide, potassium hydroxide,
tetraalkylammonium hydroxides, and the like; tertiary alkylamines
such as tributyl amine, triethylamine, dimethylbenzylamine,
dimethylbutylamine and the like; tertiary mixed alkyl-arylamines
and substituted derivatives thereof such as N,N-dimethylaniline;
heterocyclic amines such as imidazoles, pyridines, and substituted
derivatives thereof such as 2-methylimidazole, 2-vinylimidazole,
4-(dimethylamino)pyridine, 4-(1-pyrrolino)pyridine,
4-(1-piperidino)pyridine, 2-vinylpyridine, 3-vinylpyridine,
4-vinylpyridine, and the like. Also useful are organometallic salts
such as, for example, tin and zinc salts known to catalyze the
condensation of, for example, isocyanates or cyanate esters with
phenols. The organometallic salts useful in this regard are known
to the art in numerous publications and patents well known to those
skilled in this art.
[0017] The functionalized poly(arylene ether) may be a
ring-functionalized poly(arylene ether). In one embodiment, the
ring-functionalized poly(arylene ether) is a poly(arylene ether)
comprising repeating structural units of the formula ##STR12##
wherein each L.sup.1-L.sup.4 is independently hydrogen, a
C.sub.1-C.sub.12 alkyl group, an alkenyl group, or an alkynyl
group; wherein the alkenyl group is represented by ##STR13##
wherein L.sup.5-L.sup.7 are independently hydrogen or methyl, and a
is an integer from 0 to 4; wherein the alkynyl group is represented
by ##STR14## wherein L.sup.8 is hydrogen, methyl, or ethyl, and b
is an integer from 0 to 4; and wherein about 0.02 mole percent to
about 25 mole percent of the total L.sup.1-L.sup.4 substituents in
the ring-functionalized poly(arylene ether) are alkenyl and/or
alkynyl groups. Within this range, it may be preferred to have at
least about 0.1 mole percent, more preferably at least about 0.5
mole percent, alkenyl and/or alkynyl groups. Also within this
range, it may be preferred to have up to about 15 mole percent,
more preferably up to about 10 mole percent, alkenyl and/or alkynyl
groups.
[0018] The ring-functionalized poly(arylene ether) may be prepared
according to known methods. For example, an unfunctionalized
poly(arylene ether) such as poly(2,6-dimethyl-1,4-phenylene ether)
may be metallized with a reagent such as n-butyl lithium and
subsequently reacted with an alkenyl halide such as allyl bromide
and/or an alkynyl halide such as propargyl bromide. This and other
methods for preparation of ring-functionalized poly(arylene ether)
resins are described, for example, in U.S. Pat. No. 4,923,932 to
Katayose et al.
[0019] In another embodiment, the functionalized poly(arylene
ether) is the product of the melt reaction of a poly(arylene ether)
and an .alpha.,.beta.-unsaturated carbonyl compound or a
.beta.-hydroxy carbonyl compound to produce an acid- or
anhydride-functionalized poly(arylene ether). In some embodiments
both acid and anhydride functionality may be present. Examples of
.alpha.,.beta.-unsaturated carbonyl compounds include, for example,
fumaric acid, maleic acid, maleic anhydride, itaconic acid,
itaconic anhydride, citraconic acid, citraconic anhydride, as well
as various derivatives of the foregoing and similar compounds.
Examples of .beta.-hydroxy carbonyl compounds include, for example,
citric acid, malic acid, and the like. Such functionalization is
typically carried out by melt mixing the poly(arylene ether) with
the desired carbonyl compound at a temperature of about 190 to
about 290.degree. C.
[0020] There is no particular limitation on the molecular weight or
intrinsic viscosity of the functionalized poly(arylene ether). In
one embodiment, the composition may comprise a functionalized
poly(arylene ether) having a number average molecular weight of
about 1,000 to about 25,000 atomic mass units (AMU). Within this
range, it may be preferable to use a functionalized poly(arylene
ether) having a number average molecular weight of at least about
2,000 AMU, more preferably at least about 4,000 AMU. In another
embodiment, the composition may comprise a functionalized
poly(arylene ether) having an intrinsic viscosity of about 0.05 to
about 0.6 deciliters per gram (dL/g) as measured in chloroform at
25.degree. C. Within this range, the functionalized poly(arylene
ether) intrinsic viscosity may preferably be at least about 0.08
dL/g, more preferably at least about 0.1 dL/g. Also within this
range, the functionalized poly(arylene ether) intrinsic viscosity
may preferably be up to about 0.5 dL/g, still more preferably up to
about 0.4 dL/g. Generally, the intrinsic viscosity of a
functionalized poly(arylene ether) will vary insignificantly from
the intrinsic viscosity of the corresponding unfunctionalized
poly(arylene ether). Specifically, the intrinsic viscosity of a
functionalized poly(arylene ether) will generally be within 10% of
that of the unfunctionalized poly(arylene ether). It is expressly
contemplated to employ blends of at least two functionalized
poly(arylene ether)s having different molecular weights and
intrinsic viscosities. The composition may comprise a blend of at
least two functionalized poly(arylene ethers). Such blends may be
prepared from individually prepared and isolated functionalized
poly(arylene ethers). Alternatively, such blends may be prepared by
reacting a single poly(arylene ether) with at least two
functionalizing agents. For example, a poly(arylene ether) may be
reacted with two capping agents, or a poly(arylene ether) may be
metallized and reacted with two unsaturated alkylating agents. In
another alternative, a mixture of at least two poly(arylene ether)
resins having different monomer compositions and/or molecular
weights may be reacted with a single functionalizing agent. The
composition may, optionally, comprise a blend of a functionalized
poly(arylene ether) resin and an unfunctionalized poly(arylene
ether) resin, and these two components may, optionally, have
different intrinsic viscosities.
[0021] The curable composition may comprise about 5 to about 90
parts by weight of the functionalized poly(arylene ether) per 100
parts by weight total of the functionalized poly(arylene ether) and
the acryloyl monomer. Within this range, the amount of the
functionalized poly(arylene ether) resin may preferably be at least
about 10 parts by weight, more preferably at least about 15 parts
by weight. Also within this range, the amount of the functionalized
poly(arylene ether) resin may preferably be up about 80 parts by
weight, more preferably up to about 60 parts by weight, still more
preferably up to about 50 parts by weight.
[0022] The composition comprises an acryloyl monomer. In one
embodiment, the acryloyl monomer comprises at least one acryloyl
moiety having the structure ##STR15## wherein R.sup.18 and R.sup.19
are each independently selected from the group consisting of
hydrogen and C.sub.1-C.sub.12 alkyl, and wherein R.sup.18 and
R.sup.19 may be disposed either cis or trans about the
carbon-carbon double bond. Examples of acryloyl monomers having the
above structure include, for example, unsaturated polyester resins
obtained by reaction of at least one polyhydric alcohol with at
least one polybasic acid comprising an unsaturated polybasic acid.
Suitable unsaturated polyester resins are described, for example,
in U.S. Pat. No. 6,521,703 to Zarnoch et al.
[0023] In another embodiment, the acryloyl monomer comprises at
least one acryloyl moiety having the structure ##STR16## wherein
R.sup.20-R.sup.22 are each independently selected from the group
consisting of hydrogen, C.sub.1-C.sub.12 hydrocarbyl,
C.sub.2-C.sub.18 hydrocarbyloxycarbonyl, nitrile, formyl,
carboxylate, imidate, and thiocarboxylate. In one embodiment, the
acryloyl monomer comprises at least two acryloyl moieties. In
another embodiment, the acryloyl monomer comprises at least three
acryloyl moieties. Suitable acryloyl monomers include, for example,
trimethylolpropane tri(meth)acrylate, 1,6-hexanediol
di(meth)acrylate, neopentyl glycol di(meth)acrylate, ethylene
glycol di(meth)acrylate, propylene glycol di(meth)acrylate,
cyclohexanedimethanol di(meth)acrylate, butanediol
di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene
glycol di(meth)acrylate, isobornyl (meth)acrylate, methyl
(meth)acrylate, ethoxylated (2) bisphenol A di(meth)acrylate (it
will be understood that the number following the ethoxylated term
refers to the average number of ethoxy groups in the ethoxylate
chains attached to each oxygen of bisphenol A), 4-biphenyl
(meth)acrylate, 4,4'-biphenol di(meth)acrylate, and the like, and
mixtures comprising at least one of the foregoing acryloyl
monomers.
[0024] The composition may comprise about 10 to about 95 parts
acryloyl monomer per 100 parts by weight total of the
functionalized poly(arylene ether) and the acryloyl monomer. Within
this range, the amount of the acryloyl monomer may preferably be at
least about 20 parts by weight, more preferably at least about 30
parts by weight, still more preferably at least about 40 parts by
weight. Also within this range, the amount of the acryloyl monomer
may preferably be up to about 90 parts by weight, more preferably
up to about 85 parts by weight, still more preferably up to about
80 parts by weight.
[0025] The composition comprises a phosphorus flame retardant
having the formula ##STR17## wherein M.sup.d+ is a metal ion or an
onium ion; d is 1, 2, 3, or 4 according to the identity of M and
its oxidation state; each occurrence of R.sup.23 and R.sup.24 is
independently C.sub.1-C.sub.18 hydrocarbyl; and each occurrence of
m and n is 0 or 1. When M.sup.d+ is a metal ion, M may be, for
example Mg, Ca, Al, Sb, Sn, Ge, Ti, Zn, Fe, Zr, Ce, Bi, Sr, Mn, Li,
Na, or K. In particular, M.sup.d+ may be, for example, Mg.sup.2+,
Ca.sup.2+, Al.sup.3+, Sb.sup.3+, Sn.sup.4+, Ge.sup.4+, Ti.sup.4+,
Zn.sup.2+, Fe.sup.2+, Fe.sup.3+, Ce.sup.3+, Ce.sup.4+, Bi.sup.3+,
Sr.sup.2+, Mn.sup.2+, Mn.sup.3+, Mn.sup.4+, Li.sup.+, Na.sup.+ or
K.sup.+ In one embodiment, M.sup.d+ is Al.sup.3+ or Zn.sup.2+. The
ion M.sup.d+ may also be an onium cation, such as an ammonium
cation (including mono-, di-, tri-, and
tetra-(C.sub.1-C.sub.12)-hydrocarbyl ammonium cations), a
phosphonium cation (including mono-, di-, tri-, and
tetra-(C.sub.1-C.sub.12)-hydrocarbyl phosphonium cations), or a
sulfonium cation (including mono-, di-, and
tri-(C.sub.1-C.sub.12)-hydrocarbyl sulfonium cations). In another
embodiment, M.sup.d+ is Al.sup.3+. In one embodiment, each
occurrence of R.sup.23 and R.sup.24 is independently
C.sub.1-C.sub.6 alkyl. In another embodiment, each occurrence of
R.sup.23 and R.sup.24 is methyl or ethyl. In one embodiment, each
occurrence of m and n is zero. Suitable phosphorus flame retardants
include, for example, metal salts of dimethylphosphinate,
diethylphosphinate, di-n-propylphosphinate, di-n-butylphosphinate,
di-n-hexylphosphinate, dicyclohexylphosphinate,
di-2-ethylhexylphosphinate, diphenylphosphinate,
di-o-tolylphosphinate, dimethylphosphonate, diethylphosphonate,
di-n-propylphosphonate, di-n-butylphosphonate,
di-n-hexylphosphonate, dicyclohexylphosphonate,
di-2-ethylhexylphoshate, diphenylphosphonate,
di-o-tolylphosphonate, dimethylphosphate, diethylphosphate,
di-n-propylphosphate, di-n-butylphosphate, di-n-hexylphosphate,
dicyclohexylphosphate, di-2-ethylhexylphoshate, diphenylphosphate,
di-o-tolylphosphate, and the like, and mixtures thereof. A
preferred phosphorus flame retardant is aluminum
tris(diethylphosphinate). Preparation of phosphorus flame
retardants is described, for example, in U.S. Pat. Nos. 6,255,371
and 6,547,992 to Schlosser et al., and 6,355,832 and 6,534,673 to
Weferling et al.
[0026] The composition may comprise about 0.1 to about 50 parts by
weight of the phosphorus flame retardant per 100 parts by weight
total of the functionalized poly(arylene ether) and the acryloyl
monomer. Within this range, the phosphorus flame retardant amount
may preferably be at least about 1 part by weight, more preferably
at least about 4 parts by weight, still more preferably at least
about 8 parts by weight. Also within this range, the phosphorus
flame retardant amount may preferably be up to about 40 parts by
weight, more preferably up to about 30 parts by weight, still more
preferably up to about 20 parts by weight.
[0027] The composition may, optionally, comprise additional flame
retardants. In one embodiment, the composition comprises an
aromatic bisphosphoramidate flame retardant of the formula
##STR18## wherein A is a monocyclic aromatic radical and D.sup.1 is
a C.sub.1-4 primary or secondary alkyl radical or both D.sup.1
radicals taken together are ethylene. The monocyclic aromatic
radical A may be, for example, an aromatic hydrocarbon radical or
substituted aromatic hydrocarbon radical wherein the substituent(s)
may be, for example, alkyl, alkoxy, nitro or carbalkoxy groups. The
preferred aromatic radicals are phenyl, 2,6-dialkylphenyl
(especially 2,6-xylyl), and 2,3,6-trialkylphenyl or
2,4,6-trialkylphenyl (especially 2,3,6-trimethylphenyl or
2,4,6-trimethylphenyl). Each D.sup.1 radical is primary or
secondary C.sub.1-4 alkyl, preferably methyl, or both of said
radicals taken together are ethylene. Bisphosphoramidates of the
desired molecular structure may be prepared by the reaction of a
corresponding secondary diamine such as piperazine or
N,N'-dimethylethylenediamine with a diaryl chlorophosphate of the
formula (AO).sub.2POCl in the presence of a tertiary amine. This
method of preparation is described in Talley, J. Chem. Eng. Data,
volume 33, pages 221-222 (1988). When present, the aromatic
bisphosphoramidate may be used in an amount of about 0.1 to about
30 parts by weight per 100 parts by weight total of the
functionalized poly(arylene ether) and the acryloyl monomer.
[0028] In another embodiment, the composition optionally comprises
an aromatic polyphosphate flame retardant having the formula
##STR19## wherein each occurrence of R.sup.6-R.sup.8 is
independently selected from the group consisting of hydrogen,
C.sub.1-C.sub.18 hydrocarbyl, C.sub.2-C.sub.12
hydrocarbyloxycarbonyl, nitrile, formyl, carboxylate, imidate, and
thiocarboxylate; r is 2 to about 20; and each occurrence of s is 0,
1, or 2, with the proviso that at least one occurrence of s is 1.
Preferably, each occurrence of R.sup.6 is hydrogen or methyl, each
occurrence of R.sup.7 and R.sup.8 is hydrogen, r is 2 to about 10,
and each occurrence of s is 1. The aromatic polyphosphate flame
retardant may be prepared by reacting phenyl dichlorophosphate with
an excess of the dihydroxybenzene of interest in the presence of
magnesium or aluminium chloride to give the bis(hydroxyphenyl)
phenyl phosphate; this material is then reacted with the
appropriate acryloyl chloride in the presence of an acid acceptor
such as a tertiary amine to give the structure of interest. When
present, the aromatic polyphosphate flame retardant may be used in
an amount of about 0.1 to about 30 parts by weight per 100 parts by
weight total of the functionalized poly(arylene ether) and the
acryloyl monomer. The composition may, optionally, include
additional flame retardants including, for example, antimony oxides
(e.g., Sb.sub.2O.sub.5 and Sb.sub.2O.sub.3), magnesium hydroxide,
the diglycidyl ether of tetrabromobisphenol A, dibromostyrenes, and
the like.
[0029] The composition may, optionally, comprise a
nitrogen-containing flame retardant. Suitable nitrogen-containing
flame retardants include triazines, guanidines, cyanurates,
isocyanurates, ammonium polyphosphates, and the like, and mixtures
thereof. Suitable triazines include those having the formula
##STR20## wherein R.sup.25, R.sup.26, and R.sup.27 are each
independently C.sub.1-C.sub.12 alkyl, C.sub.1-C.sub.12 alkoxyl,
C.sub.6-C.sub.12 aryl, amino, C.sub.1-C.sub.12 alkyl-substituted
amino, or hydrogen. Preferred triazines include melamine (Chemical
Abstracts Service Registry No. 108-78-1), melam (3576-88-3), melem
(1502-47-2), melon (32518-77-7), ammeline (645-92-1), ammelide
(645-93-2), ureidomelamine (16439-79-5), acetoguanamine (542-02-9),
benzoguanamine (91-76-9), and the like. Triazines further include
salts and adducts of these compounds with boric acid, phosphoric
acid. Examples include melamine phosphate, melamine pyrophosphate,
and melamine polyphosphate. Suitable guanidine compounds include
guanidine, aminoguanidine, and the like; and their salts and
adducts with boric acid, carbonic acid, phosphoric acid, nitric
acid, sulfuric acid, and the like; and mixtures thereof. Suitable
cyanurate and isocyanurate compounds include the salts and adducts
of the triazine compounds with cyanuric acid and isocyanuric acid,
such as melamine cyanurate and melamine isocyanurate. The
nitrogen-containing flame retardants are known in the art, as are
methods for their preparation, and many are commercially
available.
[0030] In one embodiment, the nitrogen-containing flame retardant
synergist comprises a melamine polyphosphate represented by the
formula ##STR21## wherein g has an average value of about 3 to
about 10,000, and the ratio of f to g is about 0.5:1 to about
1.7:1. Within this range, the average value of g specifically may
be at least about 5, more specifically at least about 10. Also
within this range, the average value of g specifically may be up to
about 1,000, more specifically up to about 500. Within the above
range, the ratio of f to g specifically may be at least about
0.7:1, more specifically at least about 0.9:1. Also within this
range, the ratio of f to g specifically may be up to about 1.3:1,
more specifically up to about 1.1:1. Melamine polyphosphates may be
prepared by reacting polyphosphoric acid and melamine, as described
in U.S. Pat. No. 6,025,419 to Kasowski et al., or by heating
melamine pyrophosphate under nitrogen at 290.degree. C. to constant
weight, as described in International Patent Application No. WO
98/08898 A1 to Jacobson et al.
[0031] When present in the composition, the nitrogen-containing
flame retardant may be used in an amount of about 0.1 to about 30
parts by weight, based on 100 parts by weight total of the
functionalized poly(arylene ether) and the acryloyl monomer. Within
this range, the nitrogen-containing flame retardant synergist
amount specifically may be at least about 0.5 parts by weight, even
more specifically at least about 0.8 parts by weight. Also within
this range, the nitrogen-containing flame retardant synergist
amount specifically may be up to about 25 parts by weight, more
preferably up to about 20 parts by weight.
[0032] In one embodiment, the composition comprises the phosphorus
flame retardant and the nitrogen-containing flame retardant. In
this embodiment, the weight ratio of the phosphorus flame retardant
to the nitrogen-containing flame retardant may be about 1:1 to
about 100:1. Within this range, the ratio specifically may be at
least about 2:1, more specifically at least about 5:1. Also within
this range, the ratio may specifically be up to about 50:1, more
specifically up to about 25:1. Any of the above flame retardants
may, optionally, be used in combination with conventional flame
retardants for polyphenylene ether compositions such as, for
example, resorcinol bis(diphenyl phosphate), or bisphenol A
bis(diphenyl phosphate).
[0033] The composition may, optionally, further comprise an alkenyl
aromatic monomer. The alkenyl aromatic monomer may have the formula
##STR22## wherein each occurrence of R.sup.16 is independently
hydrogen or C.sub.1-C.sub.18 hydrocarbyl; each occurrence of
R.sup.17 is independently halogen, C.sub.1-C.sub.12 alkyl,
C.sub.1-C.sub.12 alkoxyl, or C.sub.6-C.sub.18 aryl; p is 1 to 4;
and q is 0 to 5. Unspecified positions on the aromatic ring are
substituted with hydrogen atoms. Suitable alkenyl aromatic monomers
include, for example, styrene, .alpha.-methylstyrene,
2-methylstyrene, 3-methylstyrene, 4-methylstyrene,
2-t-butylstyrene, 3-t-butylstyrene, 4-t-butylstyrene,
1,3-divinylbenzene, 1,4-divinylbenzene, 1,3-diisopropenylbenzene,
1,4-diisopropenylbenzene, styrenes having from 1 to 5 halogen
substituents on the aromatic ring, and the like, and combinations
thereof. When the composition comprises an alkenyl aromatic
monomer, it may be present at about 10 to about 500 parts by weight
alkenyl aromatic monomer per 100 parts by weight total of the
functionalized poly(arylene ether) and the acryloyl monomer. Within
this range, it may be preferable to use an alkenyl aromatic monomer
amount of at least about 25 parts by weight, more preferably at
least about 50 parts by weight. Also within this range, it may be
preferable to use an alkenyl aromatic monomer amount of up to about
300 parts by weight, more preferably up to about 100 parts by
weight.
[0034] The composition may, optionally, further comprise an allylic
monomer. An allylic monomer is an organic compound comprising at
least one, preferably at least two, more preferably at least three
allyl (--CH.sub.2--CH.dbd.CH.sub.2) groups. Suitable allylic
monomers include, for example, diallyl phthalate, diallyl
isophthalate, triallyl mellitate, triallyl mesate, triallyl
benzenes, triallyl cyanurate, triallyl isocyanurate, mixtures
thereof, partial polymerization products prepared therefrom, and
the like. When the composition comprises an allylic monomer, it may
be present at about 10 to about 500 parts by weight allylic monomer
per 100 parts by weight total of the functionalized poly(arylene
ether) and the acryloyl monomer. Within this range, it may be
preferable to use an allylic monomer amount of at least about 25
parts by weight, more preferably at least about 50 parts by weight.
Also within this range, it may be preferable to use an allylic
monomer amount of up to about 300 parts by weight, more preferably
up to about 100 parts by weight.
[0035] The curable composition may, optionally, further comprise a
curing catalyst to increase the curing rate of the unsaturated
components. Curing catalysts, also referred to as initiators, are
well known to the art and may be used to initiate the
polymerization, cure or crosslink any of numerous thermoplastics
and thermosets including unsaturated polyester, vinyl ester and
allylic thermosets. Non-limiting examples of curing catalysts are
those described in U.S. Pat. Nos. 5,407,972 to Smith et al., and
5,218,030 to Katayose et al. The curing catalyst for the
unsaturated portion of the thermoset may include any compound
capable of producing free radicals at elevated temperatures. Such
curing catalysts may include both peroxy and non-peroxy based
radical initiators. Examples of useful peroxy initiators include,
for example, benzoyl peroxide, dicumyl peroxide, methyl ethyl
ketone peroxide, lauryl peroxide, cyclohexanone peroxide, t-butyl
hydroperoxide, t-butyl benzene hydroperoxide, t-butyl peroctoate,
2,5-dimethylhexane-2,5-dihydroperoxide,
2,5-dimethyl-2,5-di(t-butylperoxy)-hex-3-yne, di-t-butylperoxide,
t-butylcumyl peroxide,
.alpha.,.alpha.'-bis(t-butylperoxy-m-isopropyl)benzene,
2,5-dimethyl-2,5-di(t-butylperoxy)hexane, di(t-butylperoxy)
isophthalate, t-butylperoxybenzoate, 2,2-bis(t-butylperoxy)butane,
2,2-bis(t-butylperoxy)octane,
2,5-dimethyl-2,5-di(benzoylperoxy)hexane,
di(trimethylsilyl)peroxide, trimethylsilylphenyltriphenylsilyl
peroxide, and the like, and mixtures comprising at least one of the
foregoing curing catalysts. Typical non-peroxy initiators include,
for example, 2,3-dimethyl-2,3-diphenylbutane,
2,3-trimethylsilyloxy-2,3-diphenylbutane, and the like, and
mixtures comprising at least one of the foregoing curing catalysts.
The curing catalyst for the unsaturated portion of the thermoset
may further include any compound capable of initiating anionic
polymerization of the unsaturated components. Such anionic
polymerization catalysts include, for example, alkali metal amides,
such as sodium amide (NaNH.sub.2) and lithium diethyl amide
(LiN(C.sub.2H.sub.5).sub.2); alkali metal and ammonium salts of
C.sub.1-C.sub.10 alkoxides; alkali metal and ammonium hydroxides;
alkali metal cyanides; organometallic compounds such as the alkyl
lithium compound n-butyl lithium and the Grignard reagent phenyl
magnesium bromide; and the like; and combinations comprising at
least one of the foregoing anionic polymerization catalysts.
[0036] In a preferred embodiment, the curing catalyst may comprise
t-butylperoxybenzoate or dicumyl peroxide. The curing catalyst may
promote curing at a temperature of about 0.degree. C. to about
200.degree. C.
[0037] When present, the curing catalyst may be used in an amount
of about 0.1 to about 10 parts by weight per 100 parts total of the
functionalized poly(arylene ether) and the acryloyl monomer. Within
this range, it may be preferred to use a curing catalyst amount of
at least about 0.5 parts by weight, more preferably at least about
1 part by weight. Also within this range, it may be preferred to
use a curing catalyst amount of up to about 5 parts by weight, more
preferably up to about 3 parts by weight.
[0038] The curable composition may, optionally, further comprise a
curing promoter to decrease the gel time. Suitable curing promoters
include transition metal salts and complexes such as cobalt
naphthanate; and organic bases such as N,N-dimethylaniline (DMA)
and N,N-diethylaniline (DEA). Preferably, cobalt naphthanate and
DMA are used in combination. When present, the promoter may be used
in an amount of about 0.05 to about 3 parts, per 100 parts total of
the functionalized poly(arylene ether) and the acryloyl
monomer.
[0039] The composition may, optionally, further comprise a curing
inhibitor, which functions to prevent premature curing of the
composition. Suitable curing inhibitors include, for example,
diazoaminobenzene, phenylacetylene, sym-trinitrobenzene,
p-benzoquinone, acetaldehyde, aniline condensates,
N,N'-dibutyl-o-phenylenediamine, N-butyl-p-aminophenol,
2,4,6-triphenylphenoxyl, pyrogallol, catechol, hydroquinone,
C.sub.1-C.sub.6-alkyl-substituted catechols, dialkylhydroquinone,
2,4,6-dichloronitrophenol, halogen-ortho-nitrophenols,
alkoxyhydroquinone, mono- and di- and polysulfides of phenols and
catechols, thiols and oximes and hydrazones of quinone,
phenothiazine, dialkylhydroxylamines, and the like, and
combinations comprising at least one of the foregoing curing
inhibitors. Preferred curing inhibitors include benzoquinone,
hydroquinone, and tert-butylcatechol. When present, the curing
inhibitor amount may be about 0.01 to about 10 parts by weight, per
100 parts by weight total of the functionalized poly(arylene ether)
resin and the acryloyl monomer. Within this range, the curing
inhibitor amount may preferably be at least about 0.1 part by
weight. Also within this range, the curing inhibitor amount may
preferably be up to about 2 parts by weight.
[0040] The composition may further comprise one or more fillers,
including particulate fillers and fibrous fillers. Examples of such
fillers well known to the art include those described in "Plastic
Additives Handbook, 4th Edition" R. Gachter and H. Muller (eds.),
P. P. Klemchuck (assoc. ed.) Hanser Publishers, New York 1993,
pages 901-948. A particulate filler is herein defined as a filler
having an average aspect ratio less than about 5:1. Non-limiting
examples of fillers include silica powder, such as fused silica and
crystalline silica; boron-nitride powder and boron-silicate powders
for obtaining cured products having high thermal conductivity, low
dielectric constant and low dielectric loss tangent; the
above-mentioned powder as well as alumina, and magnesium oxide (or
magnesia) for high temperature conductivity; and fillers, such as
wollastonite including surface-treated wollastonite, calcium
sulfate (in its anhydrous, hemihydrated, dihydrated, or trihydrated
forms), calcium carbonate including chalk, limestone, marble and
synthetic, precipitated calcium carbonates, generally in the form
of a ground particulate which often comprises 98+% CaCO.sub.3 with
the remainder being other inorganics such as magnesium carbonate,
iron oxide, and alumino-silicates; surface-treated calcium
carbonates; talc, including fibrous, modular, needle shaped, and
lamellar talc; glass spheres, both hollow and solid, and
surface-treated glass spheres typically having coupling agents such
as silane coupling agents and/or containing a conductive coating;
and kaolin, including hard, soft, calcined kaolin, and kaolin
comprising various coatings known to the art to facilitate the
dispersion in and compatibility with the thermoset resin; mica,
including metallized mica and mica surface treated with
aminosilanes or acryloylsilanes coatings to impart good physical
properties to compounded blends; feldspar and nepheline syenite;
silicate spheres; flue dust; cenospheres; finite; aluminosilicate
(atmospheres), including silanized and metallized aluminosilicate;
natural silica sand; quartz; quartzite; perlite; Tripoli;
diatomaceous earth; synthetic silica, including those with various
silane coatings, and the like.
[0041] Preferred particulate fillers include fused silica having an
average particle size of about 1 to about 50 micrometers. A
particularly preferred particulate filler comprises a first fused
silica having a median particle size of about 0.03 micrometer to
less than 1 micrometer, and a second fused silica having a median
particle size of at least 1 micrometer to about 30 micrometers. The
preferred fused silicas have essentially spherical particles,
typically achieved by re-melting. Within the size range specified
above, the first fused silica may preferably have a median particle
size of at least about 0.1 micrometer, preferably at least about
0.2 micrometer. Also within the size range above, the first fused
silica may preferably have a median particle size of up to about
0.9 micrometer, more preferably up to about 0.8 micrometer. Within
the size range specified above, the second fused silica may
preferably have a median particle size of at least about 2
micrometers, preferably at least about 4 micrometers. Also within
the size range above, the second fused silica may preferably have a
median particle size of up to about 25 micrometers, more preferably
up to about 20 micrometers. In one embodiment, the composition
comprises the first fused silica and the second fused silica in a
weight ratio of about 70:30 to about 99:1, preferably about 80:20
to about 95:5.
[0042] Fibrous fillers include short inorganic fibers, including
processed mineral fibers such as those derived from blends
comprising at least one of aluminum silicates, aluminum oxides,
magnesium oxides, and calcium sulfate hemihydrate. Also included
among fibrous fillers are single crystal fibers or "whiskers"
including silicon carbide, alumina, boron carbide, carbon, iron,
nickel, copper. Also included among fibrous fillers are glass
fibers, including textile glass fibers such as E, A, C, ECR, R, S,
D, and NE glasses and quartz. Preferred fibrous fillers include
glass fibers having a diameter of about 5 to about 25 micrometers
and a length before compounding of about 0.5 to about 4
centimeters. Many other suitable fillers are described in U.S.
Patent Application Publication No. 2001/0053820 A1 to Yeager et
al.
[0043] The formulation may also contain adhesion promoters to
improve adhesion of the thermosetting resin to the filler or to an
external coating or substrate. Also possible is treatment of the
aforementioned inorganic fillers with adhesion promoter to improve
adhesion. Adhesion promoters include chromium complexes, silanes,
titanates, zirco-aluminates, propylene maleic anhydride copolymers,
reactive cellulose esters and the like. Chromium complexes include
those sold by DuPont under the tradename VOLAN.RTM.. Silanes
include molecules having the general structure
(RO).sub.(4-n)SiY.sub.n wherein n=1-3, R is an alkyl or aryl group
and Y is a reactive functional group which can enable formation of
a bond with a polymer molecule. Particularly useful examples of
coupling agents are those having the structure (RO).sub.3SiY.
Typical examples include vinyl triethoxysilane, vinyl
tris(2-methoxy)silane, phenyl trimethoxysilane,
.gamma.-methacryloxypropyltrimethoxy silane,
.gamma.-aminopropyltriethoxysilane,
.gamma.-glycidoxypropyltrimethoxysilane,
.gamma.-mercaptopropyltrimethoxysilane, and the like. Silanes
further include molecules lacking a reactive functional group, such
as, for example, trimethoxyphenylsilane. Titanates include those
developed by S. J. Monte et al. in Ann. Chem. Tech Conf. SPI
(1980), Ann. Tech Conf. Reinforced Plastics and Composite Inst. SPI
1979, Section 16E, New Orleans; and S. J. Monte, Mod. Plastics
Int., volume 14, number 6 pg. 2 (1984). Zirco-aluminates include
those described by L. B. Cohen in Plastics Engineering, volume 39,
number 11, page 29 (1983). The adhesion promoter may be included in
the thermosetting resin itself, or coated onto any of the fillers
described above to improve adhesion between the filler and the
thermosetting resin. For example such promoters may be used to coat
a silicate fiber or filler to improve adhesion of the resin
matrix.
[0044] When present, the particulate filler may be used in an
amount of about 5 to about 95 weight percent, based on the total
weight of the composition. Within this range, it may be preferable
to use a particulate filler amount of at least about 20 weight
percent, more preferably at least about 40 weight percent. Also
within this range, it may be preferable to use a particulate filler
amount of up to about 93 weight percent, more preferably up to
about 91 weight percent.
[0045] When present, the fibrous filler may be used in an amount of
about 2 to about 80 weight percent, based on the total weight of
the composition. Within this range, it may be preferred to use a
fibrous filler amount of at least about 5 weight percent, more
preferably at least about 10 weight percent, yet more preferably at
least about 15 weight percent. Also within this range, it may be
preferred to use a fibrous filler amount of up to about 60 weight
percent, more preferably up to about 40 weight percent, still more
preferably up to about 30 weight percent.
[0046] The aforementioned fillers may be added to the thermosetting
resin without any treatment, or after surface treatment, generally
with an adhesion promoter.
[0047] The curable composition may, optionally, further comprise
one or more additives known in the art, such as, for example, dyes,
pigments, colorants, antioxidants, heat stabilizers, light
stabilizers, plasticizers, lubricants, flow modifiers, drip
retardants, antiblocking agents, antistatic agents, flow-promoting
agents, processing aids, substrate adhesion agents, mold release
agents, toughening agents, low-profile additives, stress-relief
additives, and the like, and combinations thereof. Those skilled in
the art may select suitable additives and determine suitable
amounts.
[0048] One embodiment is a curable composition, comprising: a
(meth)acrylate-capped poly(2,6-dimethyl-1,4-phenylene ether) resin,
a (meth)acrylate-capped poly(2,6-dimethyl-1,4-phenylene
ether-co-2,3,6-trimethyl-1,4-phenylene ether) resin, or a mixture
thereof; an acryloyl monomer selected from trimethylolpropane
tri(meth)acrylate, hexanediol di(meth)acrylate,
cyclohexanedimethanol di(meth)acrylate, methacryloxypropyl
trimethoxysilane, ethoxylated (2) bisphenol A di(meth)acrylate, or
a mixture thereof; an aluminophosphorus flame retardant having the
formula ##STR23## wherein each occurrence of R.sup.23 and R.sup.24
is independently C.sub.1-C.sub.6 alkyl, and each occurrence of m
and n is 0; and fused silica.
[0049] Another embodiment is a curable composition, comprising:
about 5 to abut 40 parts by weight of a (meth)acrylate-capped
poly(2,6-dimethyl-1,4-phenylene ether) resin, a
(meth)acrylate-capped poly(2,6-dimethyl-1,4-phenylene
ether-co-2,3,6-trimethyl-1,4-phenylene ether) resin, or a mixture
thereof; about 60 to about 9 parts by weight of an acryloyl monomer
selected from trimethylolpropane tri(meth)acrylate, hexanediol
di(meth)acrylate, cyclohexanedimethanol di(meth)acrylate,
methacryloxypropyl trimethoxysilane, ethoxylated (2) bisphenol A
di(meth)acrylate, or a mixture thereof; about 1 to about 50 parts
by weight of aluminum tris(diethylphosphinate); and about 100 to
about 2,000 parts by weight of fused silica; wherein all parts by
weight are based on 100 parts by weight total for the
(meth)acrylate-capped poly(arylene ether) resin and the acryloyl
monomer.
[0050] Another embodiment is a method of preparing a curable
composition, comprising: blending a functionalized poly(arylene
ether) resin; an acryloyl monomer; and a phosphorus flame retardant
having the formula ##STR24## wherein M.sup.d+ is a metal ion or an
onium ion; d is 1, 2, 3, or 4 according to the identity of M and
its oxidation state; each occurrence of R.sup.23 and R.sup.24 is
independently C.sub.1-C.sub.18 hydrocarbyl; and each occurrence of
m and n is 0 or 1, to form an intimate blend.
[0051] There is no particular limitation on the method by which the
composition is prepared. The composition may be prepared by forming
an intimate blend comprising the functionalized poly(arylene
ether), the acryloyl monomer, and the phosphorus flame retardant.
When the composition comprises an alkenyl aromatic monomer and a
capped poly(arylene ether), the composition may be prepared
directly from an unfunctionalized poly(arylene ether) by dissolving
the uncapped poly(arylene ether) in a portion of the alkenyl
aromatic monomer, adding a capping agent to form the capped
poly(arylene ether) in the presence of the alkenyl aromatic
monomer, and adding the acryloyl monomer, the phosphorus flame
retardant, and any other components to form the thermoset
composition.
[0052] There is no particular limitation on the method by which the
composition may be cured. The composition may, for example, be
cured thermally or by using irradiation techniques, including radio
frequency heating, UV irradiation and electron beam irradiation.
When heat curing is used, the temperature selected may be about
80.degree. to about 300.degree. C. The heating period may be about
5 seconds to about 24 hours. Curing may be staged to produce a
partially cured and often tack-free resin, which then is fully
cured by heating for longer periods or at higher temperatures.
[0053] One embodiment is a cured composition obtained by curing any
of the above-described curable compositions. It will be understood
that the term "curing" includes partially curing and fully curing.
Because the components of the curable composition may react with
each other during curing, the cured compositions may be described
as comprising the reaction products of the curable composition
components.
[0054] Another embodiment is an article comprising any of the cured
compositions. The curable composition is useful for fabricating a
wide range of articles, and it is particularly suitable for use as
an encapsulant for electronic devices. The composition exhibits
highly desirable properties. For example, in one embodiment, the
cured composition may exhibit a UL94 flammability rating of V-1,
preferably, V-0, at a thickness of 1 to 10 millimeters. The cured
composition may exhibit a glass transition temperature of at least
120.degree. C., preferably at least 130.degree. C., more preferably
at least 140.degree. C. The cured composition also exhibits low
moisture absorption that is highly reversible. The cured
composition dried for 24 hours at 115.degree. C. exhibits a weight
difference less than .+-.0.05%, preferably less than .+-.0.02%,
more preferably less than .+-.0.01%, after exposure to 168 hours at
85.degree. C. and 85% relative humidity and redrying for 24 hours
at 115.degree. C. By less than .+-.0.05%, it is meant that the
absolute value of the weight change is less than 0.05%.
[0055] The invention is further illustrated by the following
non-limiting examples.
EXAMPLES 1 AND 2, COMPARATIVE EXAMPLES 1-3
[0056] Several compositions were prepared and molded using the
components and amounts summarized in Table 1, where all amounts are
expressed as parts by weight (pbw). A methacrylate-capped
poly(2,6-dimethyl-1,4-phenylene ether) resin ("Methacrylate-capped
PPE") having an intrinsic viscosity of about 0.3 deciliters per
gram was prepared according to procedures described in U.S. Patent
Application Publication No. 2001/0053820 A1 to Yeager et al. Fused
silicas were obtained from Denka as FB-74 having an average
particle size of 30.4 micrometers and a surface area of 1.6
meter.sup.2/gram, and FS-20 having an average particle size of 5.0
micrometers and a surface area of 6.7 meter.sup.2/gram. Hexanediol
diacrylate was obtained from Sartomer as SR238. Trimethylolpropane
trimethacrylate (TMPTMA) was obtained from Sartomer as SR350.
Methacryloxypropyl trimethoxysilane (MAPTMS) was obtained from Dow
Corning as Z-6030. A conductive carbon black was obtained as
Printex XE-2 from Degussa. Triphenyl phosphate was obtained from
Akzo Nobel. Piperazine bis(di-(2,6-dimethylphenyl)phosphoramidate)
(sometimes referred to as piperazine diphosphonate ester) was
prepared by the reaction of 2,6-dimethylphenol (GE Plastics) with
phosphorus oxychloride in the presence of magnesium chloride to
give xylyl dichlorophosphate, which was further reacted in
methylene chloride solvent with piperazine (Aldrich) in the
presence of triethylamine (Aldrich) to give the desired product.
Aluminum tris(diethylphosphinate) was obtained as OP930 from
Clariant. A dried colloidal powder of antimony pentoxide was
obtained from Nyacol as Nyacol A1590.
[0057] Molding compounds were prepared as follows. The fused
silicas were combined with the MAPTMS in a plastic container. The
container was then placed into a two-axis, centrifugal mixer and
allowed to mix for 15 seconds at 1400 rpm. The container was then
allowed to stand and cool for 5 minutes. After cooling, the
methacrylate-capped poly(2,6-dimethyl-1,4-phenylene ether) was
added to the container, which was again placed in the centrifugal
mixer and allowed to mix for 15 seconds at 1400 rpm, allowed to
stand and cool for 1 minute, and then mixed again for 15 seconds at
1400 rpm. The remaining components of the formulation were then
added and the resulting mixture was gently folded together with a
spatula. After folding, the mixture was again placed in the
centrifugal mixer and allowed to mix for 15 second at 1400 rpm.
After the compound was allowed to cool, it was placed in a two-roll
mill for further mixing. The mill utilized a chilled roll
(35.degree. C.) and a hot roll (50-70.degree. C.) and ran at a
speed of about 8-16 meters/minute and roll ratio of 1:1-2:1. The
gap in the nip was set initially at 0.5 millimeters and was
decreased to 0.25 millimeters as mixing progressed. The molding
compound was allowed to mix on the two-roll mill for 6-10 minutes,
during which the compound was cut from the roll 10 times. After
mixing was complete, the compound was cut from the two-roll mill
and placed in a sealed jar for storage in a freezer.
[0058] Test samples ("coupons") were prepared from the molding
compound by first compression molding the material into 3.175
millimeter thick disks, and then cutting the disks into the
appropriately sized bars for testing. Compression molding of the
molding compound was performed at 150.degree. C. under a pressure
of 4.82-6.89 megapascals. A cure time of 5 minutes was sufficient
for the 3.175 millimeter thick part. After compression molding, the
plaques were post-cured in a circulating air oven at 175.degree. C.
for 1 hour. After post-curing the 3.175 millimeter thick plaques
were cut into 1.27 centimeter wide strips using a diamond-wheeled
wet saw of the kind typically used for cutting ceramic floor tile.
The 1.27 centimeter wide by 3.175 millimeter thick strips were then
cut to length for testing. After cutting was completed, the coupons
were washed thoroughly with isopropyl alcohol and dried in an
open-air oven for one to two hours at 110.degree. C. Coupons used
for moisture gain testing were then sanded smooth on their cut
edges using 180, 220, and then 400 grit sandpaper. The molded
surfaces were not sanded. After sanding was completed, the coupons
were again cleaned in isopropyl alcohol and again dried in an
open-air oven at 110.degree. C. for 2 hours.
[0059] Flammability testing was conducted according to
Underwriter's Laboratory procedure UL94 using samples 3.175
millimeters (one-eighth inch) thick and 12.7 millimeters (one-half
inch) wide. Glass transition temperatures (T.sub.g) and
coefficients of thermal expansion (CTE) were determined by thermal
mechanical analysis according to ASTM D6341. CTE values are
expressed in units of parts per million (ppm), which are equivalent
to micrometers/meter/.degree. C. Thermal Mechanical Analysis (TMA)
was performed on a TA 2950 TMA Thermo Mechanical Analyzer.
Experimental parameters were set at: 0.05 Newton of force, nitrogen
purge, and 1.0 sec/point sampling interval. The sample temperature
was ramped at 5.degree. C./min from 25.degree. C. to 250.degree. C.
then cooled at 10.degree. C./min to 0.degree. C. The second heat
ramped from 0.degree. C. at 5.degree. C./min to 250.degree. C. Data
was reported from the second heat. CTE values were measured both
above and below the glass transition temperature.
[0060] Moisture absorption of the materials was determined by
measuring the weight of a given coupon before and after
conditioning in a controlled humidity chamber. Prior to
conditioning the coupons were cut to the dimensions of
6.35.times.1.27.times.0.3175 centimeters, dried for 1 hour at
115.degree. C., and then weighed to the nearest 0.0001 gram. After
conditioning for 168 hours, at 85.degree. C. and 85% relative
humidity, the coupons were immediately weighed and then allowed to
dry overnight at ambient conditions. Following the overnight dry,
the coupons were placed in an open-air oven for 2 hours at
115.degree. C. and then immediately weighed. Weight changes are
expressed in Table 1 as a percentage relative to the pre-weighed
value.
[0061] All property results are summarized in Table 1. The UL94
flammability results show that the phosphorus flame retardant is
more effective, on a weight basis, than either triphenyl phosphate
or the piperazine phosphate compound. Only the compositions with
the phosphorus flame retardant achieved the highly desirable V-0
rating. The results also show that the compositions with phosphorus
flame retardant closely approach their initial weight after
exposure to high humidity followed by re-drying. In contrast, the
compositions with triphenyl phosphate lost weight, possibly because
of volatilization of the triphenyl phosphate, and the composition
with the piperazine phosphate gained weight, possibly because of
irreversible water absorption. TABLE-US-00001 TABLE 1 Ex. 1 Ex. 2
C. Ex. 1 C. Ex. 2 C. Ex. 3 Composition Fused silica FB-74 66.40
66.40 66.40 66.40 66.40 Fused silica FS-20 16.60 16.60 16.60 16.60
16.60 Methacrylate-capped PPE 4.25 4.10 3.97 4.25 4.10 Dicumyl
peroxide 0.32 0.32 0.32 0.32 0.32 Carbon black 0.20 0.20 0.20 0.20
0.20 4-t-Butyl catechol 0.04 0.04 0.04 0.04 0.04 Hexanediol
diacrylate 7.89 7.62 7.37 7.89 7.62 TMPTMA 2.20 2.12 2.05 2.20 2.12
MAPTMS 0.50 0.50 0.50 0.50 0.50 Aluminum tris(diethylphosphinate)
1.60 2.10 0 0 0 Piperazine diphosphonate ester 0 0 2.55 0 0
Triphenyl phosphate 0 0 0 1.60 2.10 Properties Total burn time for
5 samples (sec) 17.5 2.4 37.1 271.4 78.3 Average burn time per
sample (sec) 3.5 0.5 15.1 54.3 15.7 Continuous Burn? no no no yes
no Drip? no no no no no UL 94 rating V-0 V-0 V-1 no ranking no
ranking T.sub.g (.degree. C.) 144 144 110 101 89 CTE < T.sub.g
(ppm) 14 12 15 16 18 CTE > T.sub.g (ppm) 22 22 22 19 12 weight
change after 168 hours at +0.200 .+-. 0.004 +0.211 .+-. 0.002
+0.194 .+-. 0.006 +0.156 .+-. 0.012 +0.091 .+-. 0.042 85.degree.
C./85% RH (%) weight change after redrying (%) +0.002 .+-. 0.004
-0.007 .+-. 0.003 +0.066 .+-. 0.008 -0.011 .+-. 0.008 -0.053 .+-.
0.004
EXAMPLES 3-11
[0062] A composition was prepared and molded according to the
procedure described above. Cyclohexanedimethanol diacrylate was
obtained from Sartomer as CD 406. A partially calcium saponified
glycolic ester of montanic acid (montan wax) in a micronized form
was obtained as CERIDUST.RTM. 5551 from Clariant. A fused silica
having a median particle size of 17.7 micrometers and a surface
area of 3.1 meter.sup.2/gram was obtained as FB-570 from Denka.
Another fused silica having a median particle size of 0.7
micrometers and a surface area of 6.2 meter.sup.2/gram was obtained
as SFP-30M from Denka. A colorant blend consisted of 57 parts of
red colorant obtained as SANDOPLAST.RTM. Red G and 43 parts of
green colorant obtained as SANDOPLAST.RTM. Green GSB, both from
Clariant. Compositions are summarized in Table 2. Spiral flow
length was determined using a spiral flow mold with a channel depth
of 0.762 millimeters and a Gluco molding machine. Conditions used
for the measurements were: platen temperature, 165.degree. C.; mold
temperature, 150.degree. C.; injection pressure, 6.89 megapascals;
injection speed and time varied with the composition, but an
injection speed of about 7.62 centimeters/second was typical, as
was an injection time of about 6 seconds; cycle time, 180 seconds.
The composition may be ground to a dry powder, or converted to a
hard pellet. Shore D hardness of pellets was measured according to
ASTM D2240. A qualitative friability test was conducted by grinding
the composition using a mortar and pestle, and sieving the
resulting powder to a maximum particle size of 600 micrometers. A
composition was judged to be friable if the composition was easily
ground into a dry powder and the powder did not self-sinter after
24 hours storage at room temperature (i.e., it remained a finely
ground powder). Properties are summarized in Table 2. The results
show that the compositions exhibit high spiral flow, and that they
are suitable for handling as either pellets or powders.
TABLE-US-00002 TABLE 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7 Ex. 8 Ex. 9
Ex. 10 Ex. 11 Composition Methacrylate-capped PPE, IV = 0.12 13.18
0 25.28 22.12 18.96 15.80 12.64 0 6.32 Methacrylate-capped PPE, IV
= 0.30 0 13.18 0 0 0 0 0 9.48 6.32 Cyclohexanedimethanol diacrylate
52.71 52.71 37.91 41.07 44.23 47.39 50.55 53.71 50.55 Montan wax 0
0 2.7 2.7 2.7 2.7 2.7 2.7 2.7 Dicumyl peroxide 2.15 2.15 2.15 2.15
2.15 2.15 2.15 2.15 2.15 4-t-Butyl catechol 0.13 0.13 0.13 0.13
0.13 0.13 0.13 0.13 0.13 Aluminum tris(diethylphosphinate) 7.56
7.56 7.56 7.56 7.56 7.56 7.56 7.56 7.56 Fused silica FB-570 417.474
417.474 417.474 417.474 417.474 417.474 417.474 417.474 417.474
Fused silica SFP-30 M 46.386 46.386 46.386 46.386 46.386 46.386
46.386 46.386 46.386 Colorant 0.54 0.54 0.54 0.54 0.54 0.54 0.54
0.54 0.54 Properties Spiral Flow (meters) 1.54 0.27 0.42 0.53 0.61
0.66 0.90 -- 0.46 Pellet Hardness (Shore D durometer) 44 -- 55 55
55 -- -- -- -- Friable? yes yes yes yes yes yes yes -- yes
EXAMPLES 12-17, COMPARATIVE EXAMPLES 4-6
[0063] Seven compositions varying primarily in flame retardant type
and amount were compounded, molded, and tested for flammability
according to Underwriter's Laboratory procedure UL94. All samples
contained silica, a colorant (carbon black or Keystone Green dye),
a mold release agent (LICOWAX.RTM. S or LICOWAX.RTM. OP from
Clariant), a flame retardant (melamine polyphosphate obtained from
Ciba as MELAPUR.RTM. 200, aluminum tris(diethyl phosphinate)
obtained from Clariant as OP930, or Clariant OP1311, which is
believed to be a 9:1 weight/weight mixture of aluminum tris(diethyl
phosphinate) and melamine polyphosphate), an initiator (dicumyl
peroxide or t-butylperoxy benzoate), t-butylcatechol inhibitor, an
acryloyl monomer (ethoxylated bisphenol A dimethacrylate obtained
from Sartomer as SR348; 4-biphenyl methacrylate, CAS Reg. No.
46904-74-9, obtained from Hampford Research; or 4,4'-biphenol
dimethacrylate, CAS Reg. No. 13082-48-9, prepared according to Liu
et al., Polymer Preprints (American Chemical Society, Division of
Polymer Chemistry) (2002), 43(2), 1067), a functionalized
poly(arylene ether) (methacrylate monocapped
poly(2,6-dimethyl-1,4-phenylene ether) having an intrinsic
viscosity of about 0.3 dL/g or methacrylate dicapped
poly(2,6-dimethyl-1,4-phenylene ether) having an intrinsic
viscosity of about 0.12 dL/g). Some samples included a
styrene-maleic anhydride copolymer. Compositions and flammability
test results are presented in Table 3. The quantity "total burn
time for 5 samples (sec)" represents the total of first and second
burn times for five samples of each composition. A composition was
deemed to have passed the UL94 V-0 test if it exhibited a total
burn time less than 50 seconds with no individual sample having a
burn time greater than 10 seconds. The results, presented in Table
3, show that the aluminum tris(diethyl phosphinate) and melamine
polyphosphate are individually effective as flame retardants, and
that their combination is synergistically effective. TABLE-US-00003
TABLE 3 Ex. 12 Ex. 13 Ex. 14 Ex. 15 C. Ex. 4 C. Ex. 5 C. Ex. 6 Ex.
16 Ex. 17 Silane-treated silica 85.60 85.60 85.60 85.60 85.60 85.60
85.60 85.00 85.47% Fumed silica -- -- -- -- -- -- -- 0.50 --
Keystone Green pigment 0.20 0.20 0.20 0.20 0.20 0.20 0.20 -- --
Carbon black -- -- -- -- -- -- -- 0.36 0.20 Licowax OP 0.40 0.40
0.40 0.40 0.40 0.40 0.40 0.30 -- Licowax S -- -- -- -- -- -- -- --
0.20 Melamine polyphosphate -- -- -- -- 2.85 3.00 3.45 -- -- OP1311
1.66 1.40 1.20 -- -- -- -- 1.25 1.25 Aluminum tris(diethyl
phosphinate) -- -- -- 1.40 -- -- -- -- -- Dicumyl peroxide 0.36
0.36 0.36 0.36 0.36 0.36 0.36 -- -- t-Butyl peroxybenzoate -- -- --
-- -- -- -- 0.36 0.38 t-Butylcatechol 0.06 0.06 0.06 0.06 0.06 0.06
0.06 0.06 0.06 Ethoxylated bisphenol A dimethacrylate 9.96 10.18
10.35 10.18 8.95 8.82 8.44 2.75 2.95 4-biphenyl methacrylate -- --
-- -- -- -- -- 2.75 2.95 4,4'-biphenol dimethacrylate -- -- -- --
-- -- -- 3.67 3.94 PPE monomethacrylate, 0.30 IV 1.76 1.80 1.83
1.80 1.58 1.56 1.49 -- -- PPE dimethacrylate, 0.12 IV -- -- -- --
-- -- -- 2.18 1.74 Styrene-maleic anhydride copolymer -- -- -- --
-- -- -- 0.82 0.86 Total burn time for 5 samples (sec) 6.1 20.4
29.7 35.9 219.8 302.7 16.7 13.1 11.0 pass UL 94 V-0? yes yes yes
yes no no yes yes yes
[0064] While the invention has been described with reference to a
preferred embodiment, it will be understood by those skilled in the
art that various changes may be made and equivalents may be
substituted for elements thereof without departing from the scope
of the invention. In addition, many modifications may be made to
adapt a particular situation or material to the teachings of the
invention without departing from the essential scope thereof.
Therefore, it is intended that the invention not be limited to the
particular embodiment disclosed as the best mode contemplated for
carrying out this invention, but that the invention will include
all embodiments falling within the scope of the appended
claims.
[0065] All cited patents, patent applications, and other references
are incorporated herein by reference in their entirety.
* * * * *