U.S. patent application number 10/896567 was filed with the patent office on 2005-01-06 for phosphorus-containing flame-retardant hardeners, epoxy resins, advanced epoxy resins and cured epoxy resins.
This patent application is currently assigned to Chun-Shan Wang. Invention is credited to Lin, Ching Hsuan, Shieh, Jeng-Yueh, Wang, Chun-Shan.
Application Number | 20050004339 10/896567 |
Document ID | / |
Family ID | 21679337 |
Filed Date | 2005-01-06 |
United States Patent
Application |
20050004339 |
Kind Code |
A1 |
Wang, Chun-Shan ; et
al. |
January 6, 2005 |
Phosphorus-containing flame-retardant hardeners, epoxy resins,
advanced epoxy resins and cured epoxy resins
Abstract
The present invention discloses an active-hydrogen-containing
phosphorus compound for cross-linking a resin and for imparting
flame-retardancy to the cured resin, and in particular to a cured
frame-retardant epoxy resin prepared by reacting the hardener with
a di- or poly-functional epoxy resin via an addition reaction
between the active hydrogen and the epoxide group. The present
invention also discloses an epoxy resin made from the
active-hydrogen-containing phosphorus compound and
epihalohydrin.
Inventors: |
Wang, Chun-Shan; (Tainan,
TW) ; Shieh, Jeng-Yueh; (Tainan, TW) ; Lin,
Ching Hsuan; (Tainan, TW) |
Correspondence
Address: |
JACKSON WALKER LLP
2435 NORTH CENTRAL EXPRESSWAY
SUITE 600
RICHARDSON
TX
75080
US
|
Assignee: |
Chun-Shan Wang
|
Family ID: |
21679337 |
Appl. No.: |
10/896567 |
Filed: |
July 22, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10896567 |
Jul 22, 2004 |
|
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10066455 |
Jan 30, 2002 |
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6797821 |
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Current U.S.
Class: |
528/108 |
Current CPC
Class: |
H05K 1/0326 20130101;
C08G 59/4021 20130101; C08G 59/504 20130101; C08G 59/621
20130101 |
Class at
Publication: |
528/108 |
International
Class: |
C08G 059/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 20, 2001 |
TW |
90123251 |
Claims
What is claimed is:
1-25. (Cancelled).
26. A phosphorus-containing frame-retardant advanced epoxy resin
and cured epoxy resin having the following formula (J): 24wherein
0<h<10; T=L or M, wherein 25the formula (J) represents the
advanced epoxy resin, when T=L; and the formula (J) represents the
cured epoxy resin, when T=M; 26wherein l and m are independently
are 0, 1 or 2, and l+m>0; 27wherein R.sup.1, R.sup.2
independently are H, C1.about.C18 alkyl, C6.about.C18 aryl,
C6.about.C18 substituted aryl, C6.about.C18 aryl methylene, or
C6.about.C18 substituted aryl methylene; 28wherein R is C1-C4 alkyl
or C6-C18 aryl; and n is an integer of 0 to 5; Ep is 29or a
phenol-aldehyde novolac epoxy resin backbone, and when Ep is the
phenol-aldehyde novolac epoxy resin backbone, the flame-retardant
advanced epoxy resin and the cured epoxy resin represented by the
formula (J) is prepared by reacting a phosphorus-containing
flame-retardant hardener having the following formula (A) with a
phenol-aldehyde novolac epoxy resin having the following formula
(II) 30wherein Q, X, l and m are defined as above; 31wherein
R.sup.3 is hydrogen, or --CH.sub.3, and g is an integer of 1-6.
27. The phosphorus-containing frame-retardant advanced epoxy resin
and cured epoxy resin according to claim 26, wherein Ep in the
formula (J) is 32wherein Y is --C(CH.sub.3).sub.2--.
28. The phosphorus-containing frame-retardant advanced epoxy resin
and cured epoxy resin according to claim 26, wherein Ep in the
formula (J) is the phenol-aldehyde novolac epoxy resin backbone,
wherein R.sup.3 in the phenol-aldehyde novolac epoxy resin (II) is
--CH.sub.3.
29. The phosphorus-containing frame-retardant advanced epoxy resin
and cured epoxy resin according to claim 26, wherein R.sup.1 and
R.sup.2 are hydrogen, and n is 0.
30. The phosphorus-containing frame-retardant advanced epoxy resin
and cured epoxy resin according to claim 26, wherein X is 33
31-37. (Cancelled).
Description
FIELD OF THE INVENTION
[0001] The present invention relates generally to an
active-hydrogen-containing phosphorus compound for cross-linking a
resin and for imparting flame-retardancy to the cured resin, and in
particular to a cured frame-retardant epoxy resin prepared by
reacting the hardener with a di- or poly-functional epoxy resin via
an addition reaction between the active hydrogen and the epoxide
group. It also relates to an epoxy resin made from the
active-hydrogen-containing phosphorus compound and
epihalohydrin.
BACKGROUND OF THE INVENTION
[0002] Typical hardeners for epoxy resins and advanced epoxy resins
are phenol-formaldehyde novolac resin, dicyandiamide,
methylenedianiline, diaminodiphenyl sulfone, phthalic anhydride,
and hexahydrophthalic anhydride, etc. The advanced epoxy resins and
cured epoxy resins prepared with these hardeners do not have flame
retardancy, and thus can not meet the safety requirements.
[0003] Several approaches for modification of epoxy backbone for
enhancing the thermal properties of epoxy resins have been
reported. Aromatic bromine compounds in conjunction with antimony
oxide are widely used as a flame retardant for epoxy resins.
Tetrabromobisphenol A is a typical example of the aromatic bromine
compounds used as a flame retardant for epoxy resins. An excess
amount of epoxy resin is reacted with tetrabromobisphenol A to
prepare an advanced epoxy resin having two terminal epoxide groups,
as shown in the following formula: 1
[0004] wherein Ep is a bi-radical group of the backbone of the
epoxy resin, and m is an integer of 1-10. The advanced epoxy resin
can be used in preparing a flame-retardant printed circuit board
(FR-4) by impregnating glass fibers with the advanced epoxy resin
and heating the resulting composite to cure the advanced epoxy
resin. Furthermore, the advanced epoxy resin can be employed to
encapsulate microelectronic devices, in which the advanced epoxy
resin is cured at a high temperature with a curing agent, so that
an encapsulant having a flame-retardant property is formed. Typical
examples can be found in U.S. Pat. Nos. 3,040,495 (1961); 3,058,946
(1962); 3,294,742 (1966); 3,929,908 (1975); 3,956,403 (1976);
3,974,235 (1976); 3,989,531 (1976); 4,058,507 (1997); 4,104,257
(1978); 4,170,711 (1979); and 4,647,648(1987)].
[0005] Although the tetrabromobisphenol A-containing advanced epoxy
resin shows flame retardant property, major problems encountered
with this system are concerned with the generation of toxic and
corrosive fumes during combustion such as dioxin and
benzofuran.
[0006] The flame retardant having a small molecular weight tends to
lower the mechanical properties of the epoxy resins, and
migrate/vaporize from the epoxy resins such that the flame
retardancy thereof diminishes.
[0007] It is an object of this invention to provide a
phosphorus-containing flame retardant hardener for cross-linking a
resin and for imparting flame-retardancy to the cured resin.
[0008] It is another object of this invention to provide advanced
epoxy resins and cured epoxy resins with good thermal stability,
superior heat resistance, and without environmental problem, which
are suitable for use in making printed circuit boards and in
semiconductor encapsulation applications.
[0009] It is also an object of this invention to provide
phosphorus-containing flame-retardant epoxy resins which are
suitable for Use in making printed circuit boards and in
semiconductor encapsulation applications.
SUMMARY OF THE INVENTION
[0010] In order to accomplish the aforesaid objects, a
flame-retardant hardener containing one of the following
phosphorus-containing rigid groups was synthesized in the present
invention: 2
[0011] wherein R.sup.1 and R.sup.2 independently are H,
C1.about.C18 alkyl, C6.about.C18 aryl, C6.about.C18 substituted
aryl, C6.about.C18 aryl methylene, or C6.about.C18 substituted aryl
methylene; and Ar is an un-substituted or substituted phenyl or
phenoxy radical. The hardener of the present invention is prepared
by bounding the phosphorus-containing rigid group to bisphenol-A
(BPA), diamonodiphenyl methane (DDM), diaminodiphenyl sulfone
(BDS), melamine (MA) or dicyandiamide (DICY). The
phosphorus-containing bisphenol-A of the hardeners of the present
invention can be reacted with an excess amount of epoxy resin to
prepare a flame-retardant advanced epoxy, which is suitable for use
in making printed circuit boards.
[0012] The present invention also provides a flame-retardant epoxy
resin by reacting the hardener of the present invention with an
excess of epihalohydrin in the presence of an alkali metal
hydroxide.
[0013] The present invention also provides a cured flame-retardant
epoxy resin by using the hardener of the present invention and a
cured flame-retardant epoxy resin from the flame-retardant epoxy
resin of the present invention. The cured flame-retardant epoxy
resins so prepared have a high glass transition temperature (Tg),
high decomposition temperature and high elastic modulus, and are
free of toxic and corrosive fumes during combustion, and thus are
suitable for printed circuit board and semiconductor encapsulation
applications.
DETAILED DESCRIPTION OF THE INVENTION
[0014] A phosphorus-containing compound prepared in accordance with
the present invention has a formula selecting from the group
consisting of (A) to (I): 3
[0015] wherein
[0016] l and m independently are 0, 1 or 2, and l+m>0; i and j
independently are 0, 1 or 2, and 0<i+j<4; k is 0 or 1, and
i+k<3;
[0017] Z is --NH.sub.2, --CH.sub.3 or phenyl; 4
[0018] R.sup.1, R.sup.2 independently are H, C1.about.C18 alkyl,
C6.about.C18 aryl, C6-C18 substituted aryl, C6.about.C18 aryl
methylene, or C6.about.C18 substituted aryl methylene; 5
[0019] wherein R is C1-C4 alkyl or C6-C18 aryl; and n is an integer
of 0 to 5.
[0020] Preferably, the phosphorus-containing compound of the
present invention has a structure of the formula (A).
[0021] Preferably, the phosphorus-containing compound of the
present invention has a structure of the formula (B).
[0022] Preferably, the phosphorus-containing compound of the
present invention has a structure of the formula (C).
[0023] Preferably, the phosphorus-containing compound of the
present invention has a structure of the formula (D).
[0024] Preferably, the phosphorus-containing compound of the
present invention has a structure of the formula (E) or (F).
[0025] Preferably, the phosphorus-containing compound of the
present invention has a structure of the formula (G).
[0026] Preferably, the phosphorus-containing compound of the
present invention has a structure of the formula (H) or (I).
[0027] Preferably, R.sup.1 and R.sup.2 are hydrogen. Preferably, n
is 0.
[0028] Preferably, X is 6
[0029] when the phosphorus-containing compound of the present
invention has a structure of the formula (A).
[0030] Preferably, X is --CH.sub.2-- or 7
[0031] when the phosphorus-containing compound of the present
invention has a structure of the formula (B).
[0032] Preferably, Ar is phenoxy, when the phosphorus-containing
compound of the present invention has a structure of one of the
formulas (A) to (D).
[0033] Preferably, Ar is phenyl, when the phosphorus-containing
compound of the present invention has a structure of one of the
formulas (F) to (I).
[0034] Preferably, i and j are 0 or 1.
[0035] Preferably, Z is --NH.sub.2.
[0036] Preferably, k is 0.
[0037] The present invention also discloses a phosphorus-containing
frame-retardant advanced epoxy resin and cured epoxy resin having
the following formula (J): 8
[0038] wherein
[0039] 0<h<10;
[0040] T=L or M, wherein 9
[0041] the formula (J) represents the advanced epoxy resin, when
T=L; and
[0042] the formula (J) represents the cured epoxy resin, when
T=M;
[0043] A' is 10
[0044] wherein Q, X, l and m are defined as above; and
[0045] Ep is 11
[0046] or a phenol-aldehyde novolac epoxy resin backbone, and when
Ep is the phenol-aldehyde novolac epoxy resin backbone, the
flame-retardant advanced epoxy resin and the cured epoxy resin
represented by the formula (J) is prepared by reacting the
phosphorus-containing compound (A) with a phenol-aldehyde novolac
epoxy resin having the following formula (II) 12
[0047] wherein R.sup.3 is hydrogen, or --CH.sub.3, and g is an
integer of 1-6.
[0048] Preferably, Ep in the formula (J) is 13
[0049] wherein Y is --C(CH.sub.3).sub.2--.
[0050] Preferably, Ep in the formula (J) is the phenol-aldehyde
novolac epoxy resin backbone, wherein R.sup.3 in the
phenol-aldehyde novolac epoxy resin (II) is --CH.sub.3.
[0051] A suitable process for preparing the flame-retardant
advanced epoxy resin (J) comprises reacting the
phosphorus-containing compound (A) with an excess amount of an
epoxy resin having the following formula: 14
[0052] wherein Ep is defined as above.
[0053] The phosphorus-containing compounds (A) to (I) of the
present invention can be used as a flame-retardant hardener for an
epoxy resin, when there is more than one active hydrogen contained
therein; and can be used as a flame retardant for the epoxy resin,
if there is only one active hydrogen contained therein.
[0054] Suitable processes for preparing the phosphorus-containing
compounds (A)-(I) of the present invention include (but not
limited) processes utilizing the following reactions:
[0055] Compounds (A)-(D): Substituted BPA, DDM, DDS, MA and DICY
types 15
[0056] Compounds (E) and (F): Dicyandiamide addition product types
16
[0057] Compounds (G)-(I): Substited melamine and dicyandiamide
types 17
[0058] l, m, i, j, k, Z, X, Q and Q' in the aforesaid reactions for
synthesizing the phosphorus-containing compounds (A)-(I) are
defined as above.
[0059] The QOH reactant used in the aforesaid reactions for
synthesizing the phosphorus-containing compounds (A)-(D) may be
prepared by the following reactions (1) and (2): 18
[0060] wherein DOPO is an abbreviation of
9,10-dihydro-9-oxa-10-phosphaphe- nanthrene 10-oxide, R.sup.1 and
R.sup.2 are defined as above.
2-(6-Oxid-6H-dibenz<c,e><1,2>oxa-phosphorin-6-yl)
methanol (abbreviated as ODOPM) can be synthesized when R.sup.1 and
R.sup.2 in the reaction (1) are both hydrogen. 19
[0061] R.sup.1, R.sup.2 and Ar in the reaction (2) are defined as
above. Diphenoxy phosphoryl methanol (abbreviated as DPOM) can be
synthesized when R.sup.1, R.sup.2are both hydrogen, and Ar is
phenoxy in the reaction (2).
[0062] The Q' Cl reactant used in the aforesaid reactions for
synthesizing the phosphorus-containing compounds (G)-(I) may be
prepared by the following reactions (3) and (4): 20
[0063] wherein ODOPC in the reaction (3) is an abbreviation of
2-(6-oxid-6H-dibenz<c,e><1,2>oxa-phosphorin-6-yl)chloride;
21
[0064] wherein R, n and Ar In the reaction (4) are defined as
above. Diphenyl phosphoryl chloride (abbreviated as DPC) can be
synthesized, when R is hydrogen and Ar is phenyl in the reaction
(4).
[0065] The present invention further synthesized a
phosphorus-containing flame-retardant cured epoxy resin by curing
an epoxy resin or advanced epoxy resin with the hardener of the
present invention alone or together with the conventional curing
agent for the epoxy resin in a molten state. The conventional
curing agent for the epoxy resin preferably is selected from the
group consisting of phenol-formaldehyde novolac resin,
dicyandiamide, methylenedianiline, diaminodiphenyl sulfone,
phthalic anhydride and hexahydrophthalic anhydride. Preferably, the
curing reaction is carried out at a temperature higher than
150.degree. C. and with a stoichiometric amount of the hardener and
the curing agent, i.e. the equivalent ratio of the epoxide group in
the epoxy resin and/or advance epoxy resin and the functional
groups in the hardener and the curing agent is about 1:1. More
preferably, the curing reaction is carried out in the presence of a
curing promoter such as triphenylphosphine, and in an amount of
0.01-10.0 parts by weight of the curing promoter per 100 parts by
weight of the epoxy resin and/or advance epoxy resin. The
phosphorus-containing flame-retardant cured epoxy resin of the
present invention is suitable for use in making a flame-retardant
printed circuit board as a matrix resin and in semiconductor
encapsulation.
[0066] Preferably, the phosphorus-containing flame-retardant cured
epoxy resin of the present invention contains 0.5-30 wt %, and more
preferably 0.5-5 wt %, of phosphorus.
[0067] A suitable epoxy resin for use in the present invention can
be any known epoxy resin, for examples those having two epoxide
groups such as bisphenol A epoxy resin, bisphenol F epoxy resin,
bisphenol S epoxy resin and biphenol epoxy resin, and those having
more than two epoxide groups such as phenol formaldehyde novolac
epoxy and cresol formaldehyde novolac epoxy (CNE) with 4-18
functional groups, and mixtures thereof.
[0068] An advanced epoxy resin suitable for use in the present
invention can be prepared by conducting a curing reaction of the
conventional curing agent for an epoxy resin and using an excess
amount of an epoxy resin in a molten state.
Preparation of Phosphorus-Containing Hardeners
[0069] i). Substituted Bisphenol-A (BPA), Diamonodiphenyl Methane
(DDM), Diaminodiphenyl Sulfone (DDS), Melamine (MA) or
Dicyandiamide (DICY) Types
[0070] Preparation Example 1-A (P-1-A, ODOPM-BPA-A):
[0071] To an one liter four-inlet flask equipped with a
thermocouple and temperature controller, a reflux condenser, a
nitrogen feed and a mechanical stirrer, 1 mole (228 g) bisphenol-A
(BPA) was added, heated to 170.degree. C. and then stirred to a
molten state. 0.7 g (0.3 wt %) potassium acetate was mixed with the
molten BPA followed by adding slowly 1 mole (246 g)
2-(6-oxid-6H-dibenz<c,e><1,2>oxa-phosphorin-6-- yl)
methanol (ODOPM). The mixture was heated gradually to a temperature
of 220.degree. C. when the addition of ODOPM was completed. The
substitution reaction was continued for 6 hours. The reaction
product was dissolved in cyclohexanone, and washed with water
several times before the solvent was evaporated under vacuum to
obtain ODOPM-BPA-A (P-1-A). Yield, 98%; softening temperature,
125-132.degree. C. Phosphorus content: 6.79%.
[0072] Preparation Example 1-B (P-1-B, ODOPM-BPA-A):
[0073] To an one liter four-inlet flask equipped with a
thermocouple and temperature controller, a reflux condenser, a
nitrogen feed and a mechanical stirrer, 1 mole (228 9) bisphenol-A
(BPA) was added, heated to 170.degree. C. and then stirred to a
molten state. 1.14 g (0.5 wt %) potassium acetate was mixed with
the molten BPA followed by adding slowly 1.5 mole (369 g) ODOPM.
The mixture was heated gradually to a temperature of 220.degree. C.
when the addition of ODOPM was completed. The substitution reaction
was continued for 8 hours. The reaction product was dissolved in
cyclohexanone, and washed with water several times before the
solvent was evaporated under vacuum to obtain ODOPM-BPA-B (P-1-B).
Yield, 96%; softening temperature, 136-140.degree. C. Phosphorus
content: 8.16%.
[0074] Preparation Example 1-C (P-1-C, ODOPM-BPA-A):
[0075] To an one liter four-inlet flask equipped with a
thermocouple and temperature controller, a reflux condenser, a
nitrogen feed and a mechanical stirrer, 1 mole (228 g) bisphenol-A
(BPA) was added, heated to 170.degree. C. and then stirred to a
molten state. 1.14 g (0.5 wt %) potassium acetate was mixed with
the molten BPA followed by adding slowly 2 mole (492 g) ODOPM. The
mixture was heated gradually to a temperature of 220.degree. C.
when the addition of ODOPM was completed. The substitution reaction
was continued for 10 hours. The reaction product was dissolved in
cyclohexanone, and washed with water several times before the
solvent was evaporated under vacuum to obtain ODOPM-BPA-C (P-1-C).
Yield, 92%; softening temperature, 143-148.degree. C. Phosphorus
content: 9.06%.
[0076] Preparation Example 2 (P-2, DPOM-BPA):
[0077] To an one liter four-inlet flask equipped with a
thermocouple and temperature controller, a reflux condenser, a
nitrogen feed and a mechanical stirrer, 1 mole (228 g) bisphenol-A
(BPA) was added, heated to 170.degree. C. and then stirred to a
molten state. 0.7 g (0.3 wt %) potassium acetate was mixed with the
molten BPA followed by adding slowly 1 mole (264 g) diphenoxy
phosphoryl methanol (DPOM). The mixture was heated gradually to a
temperature of 220.degree. C. when the addition of DPOM was
completed. The substitution reaction was continued for 8 hours. The
reaction product was dissolved in cyclohexanone, and washed with
water several times before the solvent was evaporated under vacuum
to obtain DPOM-BPA (P-2). Yield, 98%; softening temperature,
118-124.degree. C. Phosphorus content: 6.54%.
[0078] Preparation Example 3 (P-3, ODOPM-DDM):
[0079] To an one liter four-inlet flask equipped with a
thermocouple and temperature controller, a reflux condenser, a
nitrogen feed and a mechanical stirrer, 1 mole (198 g)
diaminodiphenylmethane (DDM) was added, heated to 170.degree. C.
and then stirred to a molten state. 0.7 g (0.3 wt %) potassium
acetate was mixed with the molten DDM followed by adding slowly 1
mole (246 g) ODOPM. The mixture was heated gradually to a
temperature of 220.degree. C. when the addition of ODOPM was
completed. The substitution reaction was continued for 8 hours. The
reaction product was dissolved in cyclohexanone, and washed with
water several times before the solvent was evaporated under vacuum
to obtain ODOPM-DDM (P-3). Yield, 98%; softening temperature,
145-149.degree. C. Phosphorus content: 6.57%.
[0080] Preparation Example 4 (P-4, DPOM-DDM):
[0081] To an one liter four-inlet flask equipped with a
thermocouple and temperature controller, a reflux condenser, a
nitrogen feed and a mechanical stirrer, 1 mole (198 g)
diaminodiphenylmethane (DDM) was added, heated to 170.degree. C.
and then stirred to a molten state. 0.7 g (0.3 wt %) potassium
acetate was mixed with the molten DDM followed by adding slowly 1
mole (264 g) DPOM. The mixture was heated gradually to a
temperature of 220.degree. C. when the addition of DPOM was
completed. The substitution reaction was continued for 8 hours. The
reaction product was dissolved in cyclohexanone, and washed with
water several times before the solvent was evaporated under vacuum
to obtain DPOM-DDM (P-4). Yield, 98%; softening temperature,
136-141.degree. C. Phosphorus content: 6.31%.
[0082] Preparation Example 5 (P-5, ODOPM-DDS):
[0083] To an one liter four-inlet flask equipped with a
thermocouple and temperature controller, a reflux condenser, a
nitrogen feed and a mechanical stirrer, 1 mole (248 g)
diaminodiphenyl sulfone (DDS) was added, heated to 180.degree. C.
and then stirred to a molten state. 0.7 g (0.3 wt %) potassium
acetate was mixed with the molten DDS followed by adding slowly 1
mole (246 g) ODOPM. The mixture was heated gradually to a
temperature of 220.degree. C. when the addition of ODOPM was
completed. The substitution reaction was continued for 8 hours. The
reaction product was dissolved in cyclohexanone, and washed with
water several times before the solvent was evaporated under vacuum
to obtain ODOPM-DDS (P-5). Yield, 92%; softening temperature,
147-152.degree. C. Phosphorus content: 5.88%.
[0084] Preparation Example 6 (P-6, DPOM-DDS):
[0085] To an one liter four-inlet flask equipped with a
thermocouple and temperature controller, a reflux condenser, a
nitrogen feed and a mechanical stirrer, 1 mole (248 g)
diaminodiphenyl sulfone (DDS) was added, heated to 180.degree. C.
and then stirred to a molten state. 0.79 (0.3 wt %) potassium
acetate was mixed with the molten DDS followed by adding slowly 1
mole (264 g) DPOM. The mixture was heated gradually to a
temperature of 220.degree. C. when the addition of DPOM was
completed. The substitution reaction was continued for 8 hours. The
reaction product was dissolved in cyclohexanone, and washed with
water several times before the solvent was evaporated under vacuum
to obtain DPOM-DDS (P-6). Yield, 92%; softening temperature,
141-146.degree. C. Phosphorus content: 6.28%.
[0086] Preparation Example 7 (P-7, ODOPM-MA):
[0087] To an one liter four-inlet flask equipped with a
thermocouple and temperature controller, a reflux condenser, a
nitrogen feed and a mechanical stirrer, 1 mole (126 g) Melamine
(MA) and 500 ml N,N-dimethylacetamide (DMAc) were added, heated to
90.degree. C. and then stirred until MA was dissolved completely.
0.63 g potassium acetate was mixed with the resulting solution
followed by adding slowly 1 mole (246 g) ODOPM. The mixture was
heated gradually to a temperature of 168.degree. C. when the
addition of ODOPM was completed. The substitution reaction was
continued for 8 hours. The reaction mixture was cooled and
filtered, and the resulting cake was dried to obtain ODOPM-MA
(P-7). Yield, 98%; softening temperature, 129-134.degree. C.
Phosphorus content: 8.76%. Nitrogen content: 23.73%.
[0088] Preparation Example 8 (P-8, DPOM-MA):
[0089] To an one liter four-inlet flask equipped with a
thermocouple and temperature controller, a reflux condenser, a
nitrogen feed and a mechanical stirrer, 1 mole (126 g) Melamine
(MA) and 500 ml N,N-dimethylacetamide (DMAc) were added, heated to
90.degree. C. and then stirred until MA was dissolved completely.
0.63 g potassium acetate was mixed with the resulting solution
followed by adding slowly 1 mole (264 g) DPOM. The mixture was
heated gradually to a temperature of 168.degree. C. when the
addition of DPOM was completed. The substitution reaction was
continued for 8 hours. The reaction mixture was cooled and
filtered, and the resulting cake was dried to obtain DPOM-MA (P-8).
Yield, 98%; softening temperature, 124-130.degree. C. Phosphorus
content: 8.33%. Nitrogen content: 22.58%.
[0090] Preparation Example 9 (P-9, ODOPM-DICY):
[0091] To an one liter four-inlet flask equipped with a
thermocouple and temperature controller, a reflux condenser, a
nitrogen feed and a mechanical stirrer, 1 mole (86 g) dicyandiamide
(DICY) and 500 ml N,N-dimethylacetamide (DMAc) were added, heated
to 90.degree. C. and then stirred until DICY was dissolved
completely. 0.6 g potassium acetate was mixed with the resulting
solution followed by adding slowly 1 mole (246 g) ODOPM. The
mixture was heated gradually to a temperature of 168.degree. C.
when the addition of ODOPM was completed. The substitution reaction
was continued for 8 hours. The reaction mixture was cooled and
filtered, and the resulting cake was dried to obtain ODOPM-DICY
(P-9). Yield, 98%; softening temperature, 138-143.degree. C.
Phosphorus content: 9.87%. Nitrogen content: 17.83%.
[0092] Preparation Example 10 (P-10, DPOM-DICY):
[0093] To an one liter four-inlet flask equipped with a
thermocouple and temperature controller, a reflux condenser, a
nitrogen feed and a mechanical stirrer, 1 mole (86 g) dicyandiamide
(DICY) and 500 ml N,N-dimethylacetamide (DMAc) were added, heated
to 90.degree. C. and then stirred until DICY was dissolved
completely. 0.6 g potassium acetate was mixed with the resulting
solution followed by adding slowly 1 mole (264 g) DPOM. The mixture
was heated gradually to a temperature of 168.degree. C. when the
addition of DPOM was completed. The substitution reaction was
continued for 8 hours. The reaction mixture was cooled and
filtered, and the resulting cake was dried to obtain DPOM-DICY
(P-10). Yield, 98%; softening temperature, 129-135.degree. C.
Phosphorus content: 9.34%. Nitrogen content: 16.87%.
[0094] ii). Dicyandiamide Addition Product Type
[0095] Preparation Example 11 (P-11, DOPO-DICY):
[0096] To an one liter four-inlet flask equipped with a
thermocouple and temperature controller, a reflux condenser, a
nitrogen feed and a mechanical stirrer, 1 mole (86 g) dicyandiamide
(DICY) was added, heated to 120.degree. C. and then stirred to a
molten state. 1 mole (216 g)
9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) was added
slowly to the molten DICY, and the resulting mixture was heated
gradually to a temperature of 190.degree. C. when the addition of
DOPO was completed. The addition reaction was continued for 4
hours. The reaction mixture was cooled to obtain DOPO-DICY (P-11).
Yield, 96%; softening temperature, 137-143.degree. C. Phosphorus
content: 10.26%. Nitrogen content: 18.54%.
[0097] Preparation Example 12 (P-12, DPP-DICY):
[0098] To an one liter four-inlet flask equipped with a
thermocouple and temperature controller, a reflux condenser, a
nitrogen feed and a mechanical stirrer, 1 mole (86 g) dicyandiamide
(DICY) was added, heated to 120.degree. C. and then stirred to a
molten state. 1 mole (234 g) diphenyl phosphite (DPP) was added
slowly to the molten DICY, and the resulting mixture was heated
gradually to a temperature of 190.degree. C. when the addition of
DPP was completed. The addition reaction was continued for 4 hours.
The reaction mixture was cooled to obtain DPP-DICY (P-12). Yield,
96%; softening temperature, 134-138.degree. C. Phosphorus content:
9.68%. Nitrogen content: 17.50%.
[0099] iii). Substituted Melamine and Dicyandiamide Types
[0100] Preparation Example 13 (P-13, ODOPC-MA):
[0101] To an one liter four-inlet flask equipped with a
thermocouple and temperature controller, a reflux condenser, a
nitrogen feed and a mechanical stirrer, 1 mole (126 g) Melamine
(MA) and 500 ml N,N-dimethylacetamide (DMAc) were added, heated to
120.degree. C. and then stirred until MA was dissolved completely.
1 mole (251 g)
2-(6-oxid-6H-dibenz<c,e><1,2>oxa-phosphorin-6-yl)chloride
(ODOPC) was added slowly to the resulting solution. The mixture was
heated gradually to a temperature of 170.degree. C. when the
addition of ODOPC was completed. The reaction was continued for 16
hours. The reaction mixture was cooled and filtered, and the
resulting cake was dried to obtain ODOPC-MA (P-13). Yield, 94%;
softening temperature, 137-142.degree. C. Phosphorus content:
9.10%. Nitrogen content: 24.67%.
[0102] Preparation Example 14 (P-14, DPC-MA):
[0103] To an one liter four-inlet flask equipped with a
thermocouple and temperature controller, a reflux condenser, a
nitrogen feed and a mechanical stirrer, 1 mole (126 g) Melamine
(MA) and 500 ml N,N-dimethylacetamide (DMAc) were added, heated to
120.degree. C. and then stirred until MA was dissolved completely.
1 mole (253 g) diphenyl phosphoryl chloride (DPC) was added slowly
to the resulting solution. The mixture was heated gradually to a
temperature of 168.degree. C. when the addition of DPC was
completed. The reaction was continued for 10 hours. The reaction
mixture was cooled and filtered, and the resulting cake was dried
to obtain DPC-MA (P-14). Molecular weight: 558. Yield, 94%;
softening temperature, 131-135.degree. C. Phosphorus content:
9.05%. Nitrogen content: 24.53%.
[0104] Preparation Example 15 (P-15, ODOPC-DICY):
[0105] To an one liter four-inlet flask equipped with a
thermocouple and temperature controller, a reflux condenser, a
nitrogen feed and a mechanical stirrer, 1 mole (86 g) dicyandiamide
(DICY) and 500 ml N,N-dimethylacetamide (DMAc) were added, heated
to 120.degree. C. and then stirred until DICY was dissolved
completely. 1 mole (251 g) ODOPC was added slowly to the resulting
solution. The mixture was heated gradually to a temperature of
170.degree. C. when the addition of ODOPC was completed. The
reaction was continued for 8 hours. The reaction mixture was cooled
and filtered, and the resulting cake was dried to obtain ODOPC-DICY
(P-15). Molecular weight: 515. Yield, 96%; softening temperature,
134-139.degree. C. Phosphorus content: 10.32%. Nitrogen content:
18.64%.
[0106] Preparation Example 16 (P-16, DPC-DICY):
[0107] To an one liter four-inlet flask equipped with a
thermocouple and temperature controller, a reflux condenser, a
nitrogen feed and a mechanical stirrer, 1 mole (86 g) dicyandiamide
(DICY) and 500 ml N,N-dimethylacetamide (DMAc) were added, heated
to 120.degree. C. and then stirred until DICY was dissolved
completely. 1 mole (253 g) DPC was added slowly to the resulting
solution. The mixture was heated gradually to a temperature of
170.degree. C. when the addition of DPC was completed. The reaction
was continued for 8 hours. The reaction mixture was cooled and
filtered, and the resulting cake was dried to obtain DPC-DICY
(P-16). Molecular weight: 519. Yield, 96%; softening temperature,
127-132.degree. C. Phosphorus content: 10.25%. Nitrogen content:
18.51%.
[0108] Preparation of Phosphorus-Containing Advanced Epoxy Resins
and Cured Epoxy Resins
[0109] i). An Advanced Epoxy Resin Prepared from Bisphenol A Epoxy
Resin and ODOPM-BPA
[0110] Example A (P-A):
[0111] To a one liter reactor equipped with a temperature
controller, a reflux condenser, a nitrogen feed, a vacuum system
and a mechanical stirrer, 564 g diglycidyl ether of bisphenol A
(BPA epoxy resin) having an epoxide equivalent weight (EEW) of 188
was added, and heated to 110.degree. C. while stirring and
vacuuming (<100 mmHg) for a period of 30 minutes to remove a
trace amount of water contained in the epoxy resin. The vacuuming
was stopped, and dried nitrogen was introduced into the reactor
until the atmospheric pressure was reached. The temperature of the
reactor was raised to 130.degree. C., and 228 g ODOPM-BPA-A (P-1-A)
was then added while stirring. After a molten mixture of
ODOPM-BPA-A and BPA epoxy resin was formed, 500 ppm (based on total
weight) ethyl triphenyl phosphonium chloride was added, and the
temperature of the reaction mixture was increased to 160.degree. C.
and maintained at 160.degree. C. for two hours. The equivalent
ratio of epoxide group to hydroxyl group was 3.0:1 at the starting
point of the reaction. The resultant advanced epoxy resin had an
EEW of 396.
[0112] Example B (P-B):
[0113] The procedures of Example A were repeated except that
ODOPM-BPA-A (P-1-A) was replaced by ODOPM-BPA-B (P-1-B). The
equivalent ratio of epoxide group to hydroxyl group was 3.0:1 at
the starting point of the reaction. The resultant solid advanced
epoxy resin had an EEW of 424.
[0114] Example C (P-C):
[0115] The procedures of Example A were repeated except that
ODOPM-BPA-A (P-1-A) was replaced by ODOPM-BPA-C (P-1-C). The
equivalent ratio of epoxide group to hydroxyl group was 3.0:1 at
the starting point of the reaction. The resultant solid advanced
epoxy resin had an EEW of 453.
[0116] Control Example A:
[0117] The procedures of Example A were repeated except that
ODOPM-BPA-A (P-1-A) was replaced by bisphenol A. The equivalent
ratio of epoxide group to hydroxyl group was 2.04:1 at the starting
point of the reaction. The resultant solid advanced epoxy resin
(designated as Control) had an EEW of 483.
[0118] Control Example B:
[0119] The procedures of Example A were repeated except that
ODOPM-BPA-A (P-1-A) was replaced by tetrabromobisphenol A. The
equivalent ratio of epoxide group to hydroxyl group was 2.58:1 at
the starting point of the reaction. The resultant solid advanced
epoxy resin (designated as TBBA) had an EEW of 483.
[0120] Control Example C:
[0121] The procedures of Example A were repeated except that
ODOPM-BPA-A (P-1-A) was replaced by bis(3-hydroxyphenyl) phenyl
phosphate (BHPP). The equivalent ratio of epoxide group to hydroxyl
group was 2.04:1 at the starting point of the reaction. The
resultant solid advanced epoxy resin (designated as BHPP) had an
EEW of 483.
[0122] ii). Preparation of a Cured Epoxy Resin from an Advanced
Epoxy Resin
[0123] Cured epoxy resins were prepared from the advanced epoxy
resins prepared in Examples A-C and Control Examples A-C with a
curing agent selected from phenol-formaldehyde novolac resin (PN),
melamine-phenol-formaldehyde-novolac resin (MPN) and dicyandiamide
(DICY).
[0124] The advanced epoxy resin was mixed with the curing agent
(1:1 equivalent ratio) at 150.degree. C. with stirring, and the
well mixed molten mixture was poured into a hot aluminum mould,
cured in an oven at 175.degree. C. for one hour, and then postcured
at 200.degree. C. for two hours.
[0125] The thermogravimetric analysis data of the resulting cured
epoxy resins are shown in Table 1. The flame-retardant properties
of the resulting cured epoxy resins are shown in Table 2.
1TABLE 1 TGA data Temperature Temperature Rapid rate Specimens of 5
wt % of 10 wt % Tr (.degree. C.) Char yield at Advanced Content of
Tg loss, .degree. C. loss, .degree. C. Step 1 Step 1 Step 2 Step 2
700.degree. C., (%) epoxy Hardener P (%) (.degree. C.) Air N.sub.2
Air N.sub.2 Air N.sub.2 Air N.sub.2 Air N.sub.2 Control PN 0 110
417 423 445 441 466 474 634 -- 2 15 P-A PN 1.54 131 387 387 417 413
455 452 674 -- 17 24 P-B PN 2.20 120 377 383 407 401 444 441 590
597 20 26 P-C PN 2.96 115 367 367 397 393 452 438 622 614 22 27
Control MPN 0 125 393 407 417 427 474 478 623 -- 1 16 P-A MPN 1.67
143 367 377 387 397 438 450 633 -- 15 20 P-B MPN 2.36 140 357 367
377 387 415 435 641 585 18 22 P-C MPN 2.97 136 347 347 367 369 397
415 662 612 21 25 Control DICY 0 132 393 393 417 417 478 481 628
658 2 6 P-A DICY 1.86 150 367 377 387 387 433 441 627 676 12 16 P-B
DICY 2.61 140 357 363 377 387 429 419 621 692 15 19 P-C DICY 3.26
137 347 353 363 367 390 407 614 674 17 21 BHPP PN 4.27 105 345 347
361 361 380 376 532 530 35 37 TBBA PN 17.72* 124 361 363 365 367
386 380 -- -- 10 23 *Content of Br --: Step 2 of rapid rate was not
found
[0126]
2TABLE 2 Flame retardant properties (UL-94 test) Content of flame-
Burning time Specimens retardant element (%) (Sec) Fume* Drip
Classification PN Control P (0.00%) 89 - Yes V-2 P-A-PN P (1.54%)
18 -- No V-1 P-B-PN P (2.20%) 0 -- No V-0 P-C-PN P (2.96%) 0 -- No
V-0 MPN Conrol P/N (0.00/3.11%) 36 + No V-2 P-A-MPN P/N
(1.67/3.93%) 2 -- No V-0 P-B-MPN P/N (2.36/3.71%) 0 -- No V-0
P-C-MPN P/N (2.97/3.11%) 0 -- No V-0 DICY Control P/N (0.00/2.78%)
52 + No V-2 P-A-DICY P/N (1.86/3.36%) 0 -- No V-0 P-B-DICY P/N
(2.61/3.14%) 0 -- No V-0 P-C-DICY P/N (3.26/2.96%) 0 -- No V-0
TBBA/PN Br (17.72%) 1 ++ Yes V-0 BHPP/PN P (4.27%) 0 -- No V-0 *++:
heavy; +: slightly; -: scarcely; --: no fume.
[0127] The data in Tables 1 and 2 show that the cured epoxy resins
prepared from the ODOPM-BPA advanced epoxy resins of the present
invention have excellent flame retardant properties in comparison
with the conventional cured epoxy resins prepared from BPA advanced
epoxy resins, especially no fume and dripping occur in the
combustion test, and thus is very suitable for the printed circuit
board applications.
[0128] Curing of Epoxy Resins with the Phosphorus-Containing
Hardeners and Nitrogen-Phosphorus-Containing Hardeners
[0129] i). Using P-1 to P-16 Hardeners
[0130] Examples 1-16:
[0131] Cured epoxy resins were prepared from a cresol formaldehyde
novolac epoxy resin (CNE) with the hardeners P-1 to P-16 prepared
in Examples 1 to 16 in an equivalent ratio of epoxide:active
hydrogen=1:1 and with 0.2 wt % of triphenylphosphine as a curing
accelerator. The mixture was grounded into fine powders to give
thermosettable epoxy resin powders. The resin powders were cured in
a mold at 150.degree. C. and 50 kg/cm.sup.2 for a period of one
hour and then at 170.degree. C. for two hours and further postcured
at 200.degree. C. for three hours to obtain cured specimens.
[0132] Control Example 1:
[0133] The procedures of Example 1 were repeated except that
ODOPM-BPA-A (P-1-A) used in Example 1 was replaced by phenol
formaldehyde novolac resin (PN) to cure the cresol formaldehyde
novolac epoxy resin (CNE) in the curing reaction.
[0134] Control Example 2:
[0135] The procedures of Example 1 were repeated except that
ODOPM-BPA-A (P-1-A) used in Example 1 was replaced by
tetrabromobisphenol A (TBBA) to cure the cresol formaldehyde
novolac epoxy resin (CNE) in the curing reaction.
[0136] Control Example 3:
[0137] The procedures of Example 1 were repeated except that
ODOPM-BPA-A (P-1-A) used in Example 1 was replaced by
bis(3-hydroxyphenyl) phenyl phosphate (BHPP) to cure the cresol
formaldehyde novolac epoxy resin (CNE) in the curing reaction.
[0138] Control Example 4:
[0139] The procedures of Example 1 were repeated except that
ODOPM-BPA-A (P-1-A) used in Example 1 was replaced by dicyandiamide
(DICY) to cure the cresol formaldehyde novolac epoxy resin (CNE) in
the curing reaction.
[0140] Control Example 5:
[0141] The procedures of Example 1 were repeated except that
ODOPM-BPA-A (P-1-A) used in Example 1 was replaced by melamine (MA)
to cure the cresol formaldehyde novolac epoxy resin (CNE) in the
curing reaction.
[0142] Control Example 6:
[0143] The procedures of Example 1 were repeated except that
ODOPM-BPA-A (P-1-A) used in Example 1 was replaced by bisphenol A
(BPA) to cure the cresol formaldehyde novolac epoxy resin (CNE) in
the curing reaction.
[0144] Control Example 7:
[0145] The procedures of Example 1 were repeated except that
ODOPM-BPA-A (P-1-A) used in Example 1 was replaced by
diaminodiphenylmethane (DDM) to cure the cresol formaldehyde
novolac epoxy resin (CNE) in the curing reaction.
[0146] Control Example 8:
[0147] The procedures of Example 1 were repeated except that
ODOPM-BPA-A (P-1-A) used in Example 1 was replaced by
diaminodiphenyl sulfone (DDS) to cure the cresol formaldehyde
novolac epoxy resin (CNE) in the curing reaction.
[0148] The dynamic mechanical analysis (DMA) properties of the
resulting cured epoxy resins are shown in Table 3; the
thermogravimetric analysis data thereof are shown in Table 4; and
the flame-retardant properties thereof are shown in Table 5.
3TABLE 3 dynamic mechanical analysis (DMA) properties Glass
transition Flexural strength temperature at 50.degree. C. Specimens
Hardeners (Tg, .degree. C.) dyne/cm Example 1 P-1 154 6.9 Example 2
P-2 142 7.3 Example 3 P-3 232 7.8 Example 4 P-4 186 7.1 Example 5
P-5 243 8.3 Example 6 P-6 202 7.4 Example 7 P-7 226 8.1 Example 8
P-8 178 7.2 Example 9 P-9 208 8.1 Example 10 P-10 186 7.1 Example
11 P-11 223 8.5 Example 12 P-12 189 7.8 Example 13 P-13 224 8.3
Example 14 P-14 181 7.2 Example 15 P-15 225 8.3 Example 16 P-16 187
7.5 Control Ex. 1 PN 176 7.2 Control Ex. 2 TBBA 120 6.1 Control Ex.
3 BHPP 125 6.8 Control Ex. 4 DICY 243 8.1 Control Ex. 5 MA 211 8.1
Control Ex. 6 BPA 150 6.8 Control Ex. 7 DDM 238 8.5 Control Ex. 8
DDS 242 8.7
[0149]
4TABLE 4 TGA data Char Maximum thermal yield degradation (%) at
Specimens Hardener Td 10% .degree. C. temperature .degree. C.
700.degree. C. Example 1 P-1 383 413 32 Example 2 P-2 471 405 31
Example 3 P-3 373 398 42 Example 4 P-4 371 395 39 Example 5 P-5 387
401 40 Example 6 P-6 381 401 38 Example 7 P-7 387 421 37 Example 8
P-8 385 413 34 Example 9 P-9 387 421 42 Example 10 P-10 381 403 40
Example 11 P-11 395 429 38 Example 12 P-12 389 403 36 Example 13
P-13 391 411 38 Example 14 P-14 385 403 35 Example 15 P-15 395 429
42 Example 16 P-16 383 413 39 Control Ex. 1 PN 427 473 29 Control
Ex. 2 TBBA 387 407 34 Control Ex. 3 BHPP 393 409 37 Control Ex. 4
DICY 418 468 12 Control Ex. 5 MA 395 441 12 Control Ex. 6 BPA 417
446 15 Control Ex. 7 DDM 413 422 30 Control Ex. 8 DDS 417 438
28
[0150]
5TABLE 5 Flame retardant properties (UL-94 test) Burning Content of
P, N time Specimens Hardener or Br (Sec) Drip Fume Classification
Example 1 P-1 P (3.62) 0 No No V-0 Example 2 P-2 P (3.54) 0 No No
V-0 Example 3 P-3 P/N (3.75/3.39) 0 No No V-0 Example 4 P-4 P/N
(3.67/3.31) 0 No No V-0 Example 5 P-5 P/N (3.54/3.19) 0 No No V-0
Example 6 P-6 P/N (3.47/3.13) 0 No No V-0 Example 7 P-7 P/N
(2.29/6.20) 0 No No V-0 Example 8 P-8 P/N (2.25/6.11) 0 No No V-0
Example 9 P-9 P/N (3.38/6.09) 0 No Yes V-0 Example 10 P-10 P/N
(3.32/6.01) 0 No No V-0 Example 11 P-11 P/N (2.38/4.30) 0 No No V-0
Example 12 P-12 P/N (2.35/4.24) 0 No No V-0 Example 13 P-13 P/N
(2.31/6.27) 0 No No V-0 Example 14 P-14 P/N (2.30/6.25) 0 No No V-0
Example 15 P-15 P/N (3.44/6.22) 0 No No V-0 Example 16 P-16 P/N
(3.43/6.19) 0 No No V-0 Control Ex. 1 PN 0 86 Yes No V-2 Control
Ex. 2 TBBA Br (21.19) 0 Yes Yes V-0 Control Ex. 3 BHPP p (4.20) 0
No No V-0 Control Ex. 4 DICY N (6.32) 46 Yes Yes V-2 Control Ex. 5
MA N (6.31) 32 No Yes V-2 Control Ex. 6 BPA 0 91 Yes Yes V-2
Control Ex. 7 DDM N (2.81) 83 Yes Yes V-2 Control Ex. 8 DDS N
(2.67) 78 Yes Yes V-2
[0151] It can be seen from Table 3 that the cured epoxy resins of
the present invention have glass transition temperatures (Tg) about
60.degree. C. higher than that of the epoxy resin cured with the
conventional flame-retardant TBBA hardener. The data in Table 4
show that the cured epoxy resins of the present invention have a
better thermal stability and higher char yield than those of the
conventional epoxy resin cured by flame-retardant TBBA. The data in
Table 5 indicate that the cured epoxy resins of the present
invention have excellent flame retardant properties, especially no
fume and dripping occur in the combustion test, and thus is very
suitable for use in the semiconductor encapsulation applications.
The flame-retardant hardeners containing the phosphorus-containing
rigid groups disclosed in the present invention can be used to
prepare flame-retardant cured epoxy resins having improved thermal
properties and flame-retardancy, as shown in Tables 3 to 5. The
nitrogen and phosphorus elements contained in the hardeners of the
present invention have a synergistic effect in flame-retardancy of
the cured epoxy resin.
[0152] ii). Using Phosphorus-Containing BPA Hardener (P-1-A)
Prepared in Preparation Example 1-A
[0153] Various amounts of the hardener ODOPM-BPA-A (P-I-A) were
separately mixed with bisphenol (BPA) to form a mixed curing agent
for cresol formaldehyde novolac epoxy resin (CNE) to determine the
flame-retardant effect of phosphorus. The mixed curing agents
consisting of P-1-A/BPA in various weight ratios (0/100, 25/75,
50/50, 75/25, and 100/0) were prepared. Triphenyl phosphine
(Ph.sub.3P) powder was used as a curing accelerator. The CNE was
mixed with the above mixed curing agents and 0.2 wt % Ph.sub.3P in
a mill at 25.degree. C. to give thermosettable epoxy resin powders,
wherein the equivalent ratio of epoxide group to hydroxyl group is
1:1. The resin powders were cured in a mould at 150.degree. C. and
50 kg/cm.sup.2 for a period of one hour and then at 170.degree. C.
for two hours and further postcured at 200.degree. C. for three
hours to obtain cured specimens.
[0154] For comparison, various weight ratios of tetrabromobisphenol
A (TBBA) and PN (25/75, 75/25, 100/0) were also used as a curing
agent to prepare the cured specimens as above.
[0155] The cured specimens were subjected to the thermogravimetric
analysis and the UL-94 test. The results are shown in Table 6 and
Table 7.
[0156] It can be seen from Table 6 that the Tg values of the
phosphorus-containing cured epoxy resin specimens of the present
invention (P-1-A/BPA) are about 30.degree. C. higher than those of
the conventional bromine-containing cured epoxy resin specimens.
Furthermore, the phosphorus-containing cured epoxy resin specimens
of the present invention exhibit significantly higher thermal
degradation temperatures and higher char yields in comparison with
the conventional bromine-containing cured epoxy resin
specimens.
[0157] The data in Table 7 show that 1.13% phosphorus content of
the phosphorus-containing cured epoxy resin of the present
invention can produce substantially the same flame-retardant effect
as 11.92% bromine content of the conventional bromine-containing
cured epoxy resin. In addition, the phosphorus-containing cured
epoxy resin specimens of the present invention generate much less
fumes in the combustion test.
[0158] The results shown in Tables 6 and 7 indicate that the
phosphorus-containing cured epoxy resin of the present invention is
very suitable for semiconductor encapsulation applications.
6TABLE 6 TGA data Content of Temperature Temperature Rapid rate
flame- of 5 wt % of 10 wt % Tr (.degree. C.) Char yield at
retardant loss, .degree. C. loss, .degree. C. Step 1 Step 1 Step 2
Step 2 700.degree. C. (%) Specimens element Tg(.degree. C.) Air
N.sub.2 Air N.sub.2 Air N.sub.2 Air N.sub.2 Air N.sub.2 P (%)
P-1-A/BPA (0/100) 0 150 407 397 421 417 436 446 -- -- 4 15
P-1-A/BPA (25/75) 1.13 142 397 387 413 413 435 440 -- -- 8 21
P-1-NBPA (50/50) 2.08 146 383 381 405 401 425 435 620 -- 15 24
P-1-NBPA (75/25) 2.91 151 363 367 393 393 416 421 610 -- 21 27
P-1-A/BPA (100/0) 3.62 154 357 353 393 383 412 413 561 567 28 32 Br
(%) TBBA/PN (25/75) 6.39 130 371 381 379 383 385 393 -- -- 5 16
TBBA/PN (50/50) 11.92 127 369 377 379 387 385 395 -- -- 7 17
TBBA/PN (75/25) 16.82 124 363 367 369 391 387 401 -- -- 10 23
TBBA/PN (100/0) 21.29 121 367 369 371 395 391 407 -- -- 12 25 --:
Step 2 of rapid ratewas not found
[0159]
7TABLE 7 Flame retardant properties (UL-94 test) Burning Specimens
time (Sec) Fume* Drip Classification P-1-A/BPA P % 0/100 0 91 + Yes
V-2 25/75 1.13 8 + No V-0 50/50 2.08 0 -- No V-0 75/25 2.91 0 -- No
V-0 100/0 3.92 0 -- No V-0 TBBA/PN Br % 25/75 6.39 20 ++ Yes V-1
50/50 11.92 6 ++ Yes V-0 75/25 16.82 0 + No V-0 100/0 21.19 0 - No
V-0 *++: heavy; +: slightly; -: scarcely; --: no fume.
[0160] The phosphorus-containing compounds (A)-(I) of the present
invention have an active hydrogen, and thus can be used as a
staring material for the preparation of flame-retardant epoxy
resins by reacting with epihalohydrin under alkaline condition as
disclosed in U.S. Pat. No. 4,499,255. The details of this US patent
are incorporated herein by reference. The flame-retardant epoxy
resins so prepared will have one of the formulas (EP-A) to (EP-I)
as follows: 22
[0161] wherein l, m, i, j, k, Z, X, Q and Q' are defined as above;
and L' is hydrogen or 23
[0162] provided that at least two L' are L.
[0163] Preferably, the flame-retardant epoxy resins (EP-A) to
(EP-I) are prepared from the preferred phosphorus-containing
compounds of the present invention.
[0164] Preferably, the flame retardant epoxy resin has the formula
(EP-A).
[0165] Preferably, the flame retardant epoxy resin has the formula
(EP-B).
[0166] The present invention further synthesizes a
phosphorus-containing flame-retardant cured epoxy resin by curing
the epoxy resin selected from (EP-A) to (EP-I) with the
conventional curing agent for the epoxy resin, which preferably is
selected from the group consisting of pherol-formaldehyde novolac
resin, dicyandiamide and hexahydrophthalic anhydride. Preferably,
the curing reaction is carried out at a temperature higher than
150.degree. C. and with stoichiometric amount of the curing agent
(hardener). More preferably, the curing reaction is carried out in
the presence of a curing promoter such as triphenylphosphine, and
in an amount of 0.01-10.0 parts by weight of the curing promotor
per 100 parts by weight of the epoxy resin. The
phosphorus-containing flame-retardant cured epoxy resin of the
present invention is suitable for use in making a flame-retardant
printed circuit board as a matrix resin and in semiconductor
encapsulations.
[0167] Preparation of Phosphorus-Containing Epoxy Resins and Cured
Epoxy Resins
[0168] i). Preparation of Phosphorus-Containing Epoxy Resins
[0169] Example 17 (P-D):
[0170] To a reaction vessel equipped with a temperature controller,
a mechanical stirrer, a reflux condenser, a dean stark trap and a
vacuum system was added 91.2 g (0.4 equivalent) of
2-(6-oxid-6H-dibenz<c,e>- ;<1,2>oxa-phosphorin-6-yl)
methyl-bisphenol-A (ODOPM-BPA-A) (P-1-A), 185 g (2 equivalents) of
epichlorohydrin (EPI), and 54 g of 1-methoxy-2-hydroxy propane as a
solvent. After stirring at room temperature and atmospheric
pressure to thoroughly mix the contents, the temperature was raised
to 65.degree. C. and the pressure was reduced to 160 mm Hg
absolute. To the resultant solution was continuously added 32 g of
50% aqueous sodium hydroxide solution at a constant rate over a
period of 1 hour. During the addition of the sodium hydroxide, the
water was removed by codistilling with epichlorohydrin and solvent.
The distillate was condensed and introduced into the dean stark
trap, wherein two distinct phases, an aqueous phase (top) and an
organic epichlorohydrin-solvent phase (bottom) were formed. The
aqueous phase was removed continuously and disregarded. The organic
phase was continuously returned to the reactor. After completion of
the sodium hydroxide addition, the reaction mixture was maintained
at a temperature of 65.degree. C. and a pressure of about 160 mm Hg
absolute for an additional 30 minutes. The reaction mixture was
washed with deionized water two or three times to remove salt after
cooling, and subsequently distilled to remove residual EPI
resulting in a phosporus-containing epoxy resin (P-D) having an
epoxide equivalent weight (EEW) of 298-301.
[0171] Example 18 (P-E):
[0172] The procedures of Example 17 were repeated except that 82.8
g (0.4 equivalent)
2-(6-oxid-6H-dibenz<c,e><1,2>oxa-phosphorin-6-yl)
methyl-4,4'-biphenol-A (ODOPM-BP) was used to replace ODOPM-BPA-A
(P-1-A). The resultant phosphorus-containing epoxy resin (P-E) had
an EEW of 279-281.
[0173] Example 19 (P-F):
[0174] The procedures of Example 17 were repeated except that 95.6
g (0.4 equivalent)
2-(6-oxid-6H-dibenz<c,e><1,2>oxa-phosphorin-6-yl)
methyl-4,4'-sulfonyl diphenol-A (ODOPM-SDP) was used to replace
ODOPM-BPA-A (P-1-A). The resultant phosphorus-containing epoxy
resin (P-F) had an EEW of 315-319.
[0175] Control Example 9 (BPA-9):
[0176] The procedures of Example 17 were repeated except that 45.6
g (0.4 equivalent) bisphenol-A (BPA) was used to replace
ODOPM-BPA-A (P-1-A). The resultant phosphorus-containing epoxy
resin (BPA-9) had an EEW of 181-185.
[0177] Control Example 10 (BP-10):
[0178] The procedures of Example 17 were repeated except that 37.2
g (0.4 equivalent) 4,4'-biphenol-A (BP) was used to replace
ODOPM-BPA-A (P-1-A). The resultant phosphorus-containing epoxy
resin (BP-10) had an EEW of 159-162.
[0179] Control Example 11 (SDP-11):
[0180] The procedures of Example 17 were repeated except that 50 g
(0.4 equivalent) 4,4'-sulfonyl diphenol (SDP) was used to replace
ODOPM-BPA-A (P-1-A). The resultant phosphorus-containing epoxy
resin (SDP-11) had an EEW of 191-195.
[0181] Control Example 12 (TBBA-12):
[0182] The procedures of Example 17 were repeated except that 108.8
g (0.4 equivalent) tetrabromobisphenol A (TBBA) was used to replace
ODOPM-BPA-A (P-1-A). The resultant phosphorus-containing epoxy
resin (TBBA-12) had an EEW of 356-359.
[0183] Control Example 13 (BHPP-13):
[0184] The procedures of Example 17 were repeated except that 71.6
g (0.4 equivalent) bis(3-hydroxyphenyl) phenyl phosphate (BHPP) was
used to replace ODOPM-BPA-A (P-1-A). The resultant
phosphorus-containing epoxy resin (BHPP-13) had an EEW of
253-256.
[0185] ii). Preparation of a Cured Epoxy Resin from a
Phosphorus-Containing Epoxy Resin
[0186] Cured epoxy resins were prepared from the epoxy resins
prepared in Examples 17-19 and Control Examples 9-13 with
phenol-formaldehyde novolac resin (PN) as a curing agent.
[0187] The epoxy resin was mixed with the curing agent (1:1
equivalent ratio) at 150.degree. C. with stirring, and the well
mixed molten mixture was poured into a hot aluminum mould, cured in
an oven at 170.degree. C. for one hour, and then postcured at
200.degree. C. for two hours.
[0188] The dynamic mechanical analysis (DMA) properties of the
resulting cured epoxy resins are shown in Table 8; the
thermogravimetric analysis data thereof are shown in Table 9; and
the flame-retardant properties thereof are shown in Table 10.
8TABLE 8 dynamic mechanical analysis (DMA) properties Glass
transition Flexural strength temperature at 50.degree. C. Specimens
Epoxy resins (Tg, .degree. C.) dyne/cm Example 17 P-D 132 6.5
Example 18 P-E 127 6.9 Example 19 P-F 189 8.1 Control Ex. 9 BPA-9
127 6.3 Control Ex. 10 BP-10 121 6.5 Control Ex. 11 SDP-11 187 8.3
Control Ex. 12 TBBA-12 117 6.3 Control Ex. 13 BHPP-13 105 6.9
[0189]
9TABLE 9 TGA data Char Maximum thermal yield Epoxy degradation (%)
at Specimens resins Td 10% .degree. C. temperature .degree. C.
700.degree. C. Example 17 P-D 397 427 42 Example 18 P-E 401 441 44
Example 19 P-F 381 398 38 Control Ex. 9 BPA-9 417 442 26 Control
Ex. 10 BP-10 425 456 24 Control Ex. 11 SDP-11 393 409 18 Control
Ex. 12 TBBA-12 409 418 35 Control Ex. 13 BHPP-13 377 393 38
[0190]
10TABLE 10 Flame retardant properties (UL-94 test) Epoxy Content of
Burning Specimens resins P or Br time (Sec) Drip Fume
Classification Example 17 P-D P (4.04) 0 No No V-0 Example 18 P-E P
(4.29) 0 No No V-0 Example 19 P-F P (3.88) 0 No No V-0 Control Ex.
9 BPA-9 0 81 No Slightly V-2 Control Ex. 10 BP-10 0 93 No Slightly
V-2 Control Ex. 11 SDP-11 0 72 Yes Yes V-2 Control Ex. 12 TBBA-12
Br (37.7) 0 No No V-0 Control Ex. 13 BHPP-13 P (4.64) 0 No No
V-0
[0191] It can be seen from Table 8 that the cured epoxy resins of
the present invention have glass transition temperatures (Tg) about
higher than those of the conventional bisphenol-A cured epoxy resin
and the conventional flame-retardant TBBA cured epoxy resin. The
data in Table 9 show that the cured epoxy resins of the present
invention have a better thermal stability and higher char yield
than those of the conventional flame-retardant TBBA epoxy resin
cured by phenol-formaldehyde novolac resin (PN). The data in Table
10 indicate that the cured epoxy resins of the present invention
have excellent flame retardant properties, especially no fume and
dripping occur in the combustion test, and thus is very suitable
for use in the semiconductor encapsulation applications. The
flame-retardant epoxy resins containing the phosphorus-containing
rigid group (ODOPM) bonded to BPA, BP and SDP disclosed in the
present invention can be used to prepare flame-retardant cured
epoxy resins having improved thermal properties and
flame-retardancy, as shown in Tables 8 to 10.
[0192] The presently disclosed embodiments are therefore considered
in all respects to be illustrative and not restrictive. The scope
of the invention is indicated by the appended claims rather than
the foregoing description, and all changes that come within the
meaning and range of equivalents thereof are intended to be
embraced therein.
* * * * *