Method of preparing polyphenylene oxide composition and laminates using such compositions

A method of preparing a film-forming polyphenylene oxide (PPO) composition as well as a laminate using such composition, wherein a setting means selected from the group consisting of a crosslinking monomer, a crosslinking polymer, and mixtures thereof, and, optionally, an initiator are added to and mixed with PPO, and a sufficient film-forming property is provided to PPO by allowing the setting means and, if present, the initiator to crosslink, whereby the PPO composition has the ability to form a film. Further, when a plurality of such films are stacked and integralized to form a melt-clad laminate, the laminate exhibits low dielectric constant and loss, so as to be used effectively in superhigh frequency bands such as the X band used for satellite communication.

TECHNICAL BACKGROUND OF THE INVENTION 
This invention relates to methods of preparing polyphenylene oxide 
compositions as well as laminates, in particular, metal-clad laminates 
that use such compositions. 
The present polyphenylene oxide compositions should be in the for of film 
members. A plurality these film members are stacked and integralized into 
the metal-clad laminate with either or both of an overlaying and 
interpositions of metal foil or foils that form the desired electric 
circuit or circuits. Because the obtained laminate is excellent in high 
frequency characteristic, particularly in the dielectric characteristics, 
they find an effective utility in use with such super high frequency bands 
as, for example, the X-band of 10 GHz used in satellite communication or 
the like. 
DISCLOSURE OF PRIOR ART 
In general, for laminate materials to be effectively used in the superhigh 
frequency band for satellite communication or the like, the laminate 
materials must be excellent in the dielectric constant and dielectric loss 
at least in respect to the environmental resistance, and preferably low in 
the dielectric constant and loss, so as to achieve the desired high 
dielectric characteristics. To this end, poly-4-fluoroethylene, 
crosslinked polyethylene and alumina ceramics have been used as the 
materials for such laminates. However, poly-4-fluoroethylene and 
crosslinked polyethylene have proven to be defective in that they both 
have low glass-transition points and are likely to vary remarkably in the 
dielectric constant and loss when used in conjunction with high frequency 
bands. Alumina ceramics have also exhibited drawbacks. Thus, while its 
dielectric constant and loss are known to be relatively constant, its 
workability is poor, specifically when used for preparing the metal-clad 
laminate. Also, no simple and favorable process has been found for forming 
the electric circuits with, for example, a copper foil and the alumina 
ceramics. 
As for other materials which are constant in the dielectric constant and 
loss, i.e., materials low in the dielectric constant and relatively high 
in the glass-transition point, there can be enumerated polyether sulfone, 
polyetherimide, polysulfone and the like which are considered to be 
suitable, in their normal state, for adhering to the metal foil for the 
circuit arrangement. However, their thermoplasticity creates problems that 
arise upon wiring connections with respect to the metal foil circuit by 
means of a soldering, the heat of which causes a deterioration in their 
adhesion. 
It has been proposed in U.S. Pat. No. 4,059,568 to use polyphenylene oxide 
(hereinafter referred to as "PPO") which has a high glass-transition point 
and is known to yield excellent results, particularly when used in 
laminate materials to be utilized with superhigh frequency bands. However, 
the thermoplasticity of PPO still leaves the problem of the poor heat 
resistance unsolved. In this case, an optimum and reliable measure for 
improving the heat resistance of PPO would be to have it crosslinked, but 
it is impossible to crosslink PPO by a simple crosslinking process, such 
as the application of heat that is effective with thermosetting resins. 
It may be possible to provide a required heat resistance to PPO by blending 
PPO with a thermosetting resin. However, this causes a problem to arise in 
that, when the blending is carried out by means of melt extrusion, the 
inherently required high temperature melting results in a gelation of the 
resin so as to render its further processing difficult. Also, the blending 
of the thermosetting resin with PPO may deteriorate the dielectric 
characteristics and eventually the high frequency characteristic of PPO. 
Further, while calendering may be employed to obtain sheet materials of a 
PPO composition that contains a thermosetting resin so as to form the 
metal-clad laminate with such sheet materials and the metal foil or foils 
properly stacked, such calendering creates a gelation problem similar to 
that caused by the melt extrusion. 
Of course, if PPO could be processed into films by means of 
solvent-casting, such processing would be preferable because the casting 
could be performed at a lower temperature. However, the film casting of 
PPO alone has been difficult and, thus, it has been attempted to render 
PPO adaptable to simple and inexpensive casting processing by means of 
adding a crosslinking agent so as to obtain films of the PPO composition. 
Thus, K. Kariya et al. have suggested in Japanese Patent Application 
Laid-Open Publication No. 59-193,929 a method in which 1,2-polybutadiene 
is added to and mixed with PPO. A substrate consisting of fiberglass or 
the like is impregnated with this mixture and subjected to thermodrying. 
This renders the mixture to be in an intermediate or prepreg in B-stage. A 
plurality of such prepregs are stacked and pressed into a laminate. 
However, in this case the substrate itself is poor in the dielectric 
characteristics because of the use of the fiber glass or the like so that, 
notwithstanding the high dielectric characteristics of PPO, the eventually 
obtained laminate cannot maintain the desired high dielectric 
characteristics and is unsuitable for use in such superhigh frequency 
bands as the X band. 
TECHNICAL FIELD OF THE INVENTION 
A primary object of the present invention is, therefore, to provide a 
method of preparing polyphenylene oxide (PPO) compositions which can be 
formed into any required types of films in a lower temperature atmosphere 
so as to lower the production costs. Such a film is effectively used in 
forming the metal-clad laminates suitable for use in the superhigh 
frequency band. 
According to the present invention, this object can be realized by 
providing a method of preparing a PPO composition, wherein a setting means 
containing at least one polyfunctional component, for example, selected 
from the group consisting of a crosslinking monomer, a crosslinking 
polymer, and mixtures thereof, and, optionally, an initiator are added to 
and mixed with PPO, and a sufficient film-forming property is provided to 
PPO by allowing e.g., the setting means and, if present, the initiator to 
crosslink, whereby a film-forming property is provided to PPO. 
The "PPO composition" should not be limited to be the only one for forming 
the film, and the term "composition" herein used is to mean the 
composition in a state different from that of any finally hardened or 
cured resin material, including an intermediate setting state between A 
and C stages, such as the state of prepreg in B stage where any subsequent 
physical processing can be carried out. 
Other objects and advantages of the present invention shall become clear 
from the following description of the invention detailed with reference to 
preferred examples of the invention.

While the present invention shall now be described with reference to the 
preferred examples, it should be understood that the intention is not to 
limit the invention only to the particular examples but rather to cover 
all alterations, modifications, and equivalent methods possible within the 
scope of appended claims. 
DISCLOSURE OF PREFERRED EMBODIMENTS 
According to a first feature of the present invention, styrene copolymer 
(hereinafter referred to as "STP") and polybutadiene (hereinafter referred 
to as "PB") are added to and mixed with PPO to provide thereto a 
film-forming property and obtain a PPO composition in the form of a film. 
As used herein, PPO is a resin of the following general structural formula, 
##STR1## 
where R is a hydrocarbon radical having hydrogen or carbon of 1 to 3 in 
number and the respective R's may be all the same or different. For 
example, PPO may be poly-(2,6-dimethyl-1,4-phnylene oxide) having 
preferably a weight-average molecular weight (Mw) of 50,000 and a 
molecular-weight distribution (Mw/Mn) of 4.2 (Mn being a number-average 
molecular weight). 
Desirably used as STP is styrene-butadiene-block copolymer, 
styrene-isoprene-block copolymer or the like. The polymer state should 
desirably be of a high molecular weight. The block state may be, assuming 
that A and B represent polystyrene and polybutadiene (or polyisoprene), 
respectively, any of AB, ABA, ABAB and so on. PB is preferably, for 
example, one or a mixture of at least two of 1,2-polybutadiene, 
1,4-polybutadiene, maleic-, acrylic- or epoxy-modified 1,2-polybutadiene 
and the like. PPO, STP, and PB may, of course, be of any other structure 
and need not be restricted to the foregoing ones. 
It has been found that when PPO is present in an amount from 9 to 71 weight 
%, STP is present in an amount from above 19 and below 91 weight % and PB 
is present in an amount from below 40 weight %, a PPO composition in the 
form of a favorable film can be obtained. Referring now to the triangular 
diagram of FIG. 1 showing the composition ratios of PPO, STP and PB which 
are taken respectively on each of three sides of the diagram, zone C1, 
shaded with rightward upward hatches, denotes the area in which favorable 
PPO compositions are obtained; within zone D1, shown within the zone C1 as 
shaded with leftward upward hatches, more preferred PPO compositions are 
obtained, and within zone E1, shown within the zone D1 as shaded with 
vertical hatches, in which PPO is present in an amount above 20 and below 
70 weight %, STP is present in an amount above 30 and below 80 weight %, 
and PB is present in an amount below 20 weight %, a substantially optimum 
PPO composition is obtained. 
While the foregoing three component resins are usually mixed as dissolved 
in a solvent, it has been found preferable that the solid resin content be 
in a range of 10 to 30 weight As the solvent, one or a mixture of at least 
two of such halogenated hydrocarbons as trichloroethylene (Trichlene), 
trichloroethane, chloroform, methylene chloride and the like, such 
aromatic hydrocarbon as benzene, chlorobenzene, toluene, xylene and the 
like, carbon tetrachloride and the like may be used, but it is preferable 
to employ trichloroethylene alone or in a mixture thereof with other 
solvent. 
In obtaining the PPO composition in the form of a film, it is preferred to 
employ a solvent-mold casting. More specifically, the mixture solution of 
PPO, STP and PB in the solvent is cast to be, for example, 5 to 700 .mu.m 
thick on a planished iron plate, a casting carrier film or the like. When 
the casting carrier film is employed, such a resin film that is insoluble 
to the solvent such as polyethylene terephthalate (hereinafter referred to 
as "PET"), polyethylene, polypropylene, polyimide or the like can be used. 
Then, the cast solution is subjected to air-drying and/or hot air 
processing to remove the solvent from the solution. It is preferable that 
the drying temperature range be set to be lower at its upper limit than 
the boiling temperature of the solvent or, in the case of drying as left 
on the carrier film, lower than the heat-resistant temperature of the 
carrier film, while the lower limit is set taking into consideration the 
necessary drying time or the desired ease of processing. When, for 
example, trichlorethylene (hereinafter referred to as "TCE") and PET film 
are used, respectively, as the solvent and carrier film, the drying 
temperature range is set to be higher than a room temperature but lower 
than 80.C. The higher the drying temperature within this drying 
temperature range, the shorter the drying time. 
The term "film" herein used as the PPO composition should be interpreted in 
the broad sense and thus should include sheet, film, tape, layer, web or 
any equivalent thereto. The surface area or length perpendicular to the 
thickness direction of such products should not be restricted, and the 
thickness may be suitably set as required depending on the intended use. 
EXAMPLE 1 
In a reactor having a defoamer and of a capacity of 2 liters, 80 g of PPO, 
80 g of styrene-butadiene-block copolymer as STP, 40 g of PB and then 800 
g of TCE were added and sufficiently stirred to mix them until a 
homogeneous solution was obtained. The solution was thereafter defoamed 
and then applied onto a PET casting film to form thereon a film of 500 
.mu.m thick. In this state, the thus formed film was subjected to 
air-drying and then to drying with blown air heated to 50.degree. C., 
after which the dried film was released from the PET film and further 
dried for 30 minutes under a heat of 120.degree. C. As a result, the PPO 
composition film thus obtained was of a thickness of about 100 .mu.m. 
EXAMPLES 2 to 10 
Different PPO compositions were obtained through the same steps as in 
EXAMPLE 1 but with the composition ratios of PPO, STP and PB as shown in 
TABLE 1. 
COMATIVE EXAMPLES 1 to 6 
The ratios of PPO, STP and PB were varied as also shown in TABLE 1, 
solutions were prepared, and an attempt was made to obtain films through 
the same steps as in EXAMPLE 1. 
TABLE 1 
__________________________________________________________________________ 
EXAMPLES 
1 2 3 4 5 6 7 8 9 10 
__________________________________________________________________________ 
(1) 
PPO (g) 
80 40 120 
65 130 
60 30 90 25 20 
(2) 
STP (g) 
80 120 
70 130 
50 90 155 
50 100 
140 
(3) 
PB (g) 
40 40 10 20 20 50 15 60 75 40 
__________________________________________________________________________ 
COMATIVE EXAMPLES 
1 2 3 4 5 6 
__________________________________________________________________________ 
(1) 200 40 10 140 60 160 
(2) 0 0 140 20 40 40 
(3) 0 160 50 40 100 0 
__________________________________________________________________________ 
The obtained compositions were observed and tested in respect to the 
presence or absence of film-forming property, homogeneity, surface 
tackiness and tensile strength. The results are shown in TABLE 2 below, in 
which "X" indicates excellent state while hyphen "-" indicates an 
unmeasureable state. 
TABLE 2 
__________________________________________________________________________ 
EXAMPLES 
1 2 3 4 5 6 7 8 9 10 
__________________________________________________________________________ 
(1) 
Film-form. prop. 
X X X X X X X X X X 
(2) 
Homogeneity 
X X X X X X X X X X 
(3) 
Surface tack. 
X X X X X X X X X X 
(4) 
Tensile streng. 
350 
300 
400 
350 
400 
350 
250 
300 
200 
200 
(Kgf/cm.sup.2) 
__________________________________________________________________________ 
COMATIVE EXAMPLES 
1 2 3 4 5 6 
__________________________________________________________________________ 
(1) no 
no no 
no no 
no 
(2) -- 
-- -- 
-- -- 
-- 
(3) -- 
-- -- 
-- -- 
-- 
(4) -- 
-- -- 
-- -- 
-- 
__________________________________________________________________________ 
Referring also to FIG. 1 in which circular dots represent the composition 
ratios of EXAMPLES 1 to 10 and square dots represent those of COMATIVE 
EXAMPLES 1 to 6, it will be seen that the composition ratios of PPO, STP 
and PB used in EXAMPLES 1 to 10 reach favorable results, while the 
composition ratios of COMATIVE EXAMPLES which are outside zone Cl 
produce no film. 
According to a second feature of the present invention, PPO, polystyrene 
(hereinafter referred to as "PS"), triallyl isocyanurate (hereinafter 
referred to as "TAIC") and/or triallyl cyanurate (hereinafter referred to 
as "TAC") are mixed to provide a film-forming property and obtain a PPO 
composition. PPO has the same structure as that used in the foregoing 
EXAMPLES 1 to 10. PS should preferably be the one of a high molecular 
weight for the purpose of improving the film-forming property. Further, 
while TAIC and TAC are respectively an isomer, from the viewpoint of 
chemical structure, it has been known that they have substantially the 
same film-forming property, compatibility, solubility and reactivity, and 
either one or both of them may be used. 
Referring next to FIG. 2 showing composition ratios of PPO, PS and TAIC in 
a triangular diagram, the three components being taken respectively on 
each of three sides of the triangle, it is seen that favorable PPO 
compositions can be obtained in a zone C2 shaded by rightward upward 
hatches. That is, when the PPO is present in an amount from 10 to 90 
weight PS is present in an amount less than 90 weight % and TAIC (and/or 
TAC) is present in an amount below 60 weight % favorable results are 
obtained. Further, in a zone D2, located within the zone C2 and shaded 
with leftward upward hatches, more preferred PPO compositions can be 
obtained. In addition, in a zone E2, located within the zone D2 and shaded 
by vertical hatches, where PPO is present in an amount from 30 to 70 
weight PS is present in an amount from 20 to 60 weight % and TAIC (and/or 
TAC) is present in an amount from 10 to 40 weight %, substantially optimum 
PPO compositions particularly in the form of films can be obtained. 
In mixing PPO, PS and TAIC (and/or TAC), the same solvent as explained in 
connection with the first feature can be used, and their resultant 
solutions can be processed into films substantially through the same steps 
as those of the casting explained in connection with the first feature. 
EXAMPLE 11 
120 g of PPO, 40 g of PS, 40 g of TAIC, and 800 g of TCE as solvent were 
put in a reactor having defoamer and of a capacity of 2 liters, and 
sufficiently stirred and mixed until a homogeneous solution was obtained. 
The solution was applied onto a PET casting film to be a film of 500 .mu.m 
thick, by means of a coater. The film in this state was subjected to 
air-drying and further dried under a heat of 50.degree. C. After the 
drying the film formed on the PET casting film was released therefrom and 
then heated at 120.degree. C. to be dried for 30 minutes. The obtained PPO 
composition film had a thickness of about 100 .mu.m. 
EXAMPLES 12 to 21 
The composition ratio of PPO, PS and TAIC was variously changed as shown in 
the following TABLE 3, and PPO composition films were obtained through the 
same steps as in EXAMPLE 11. 
COMATIVE EXAMPLES 7 to 11 
The composition ratio of PPO, PS and TAIC was further changed as shown also 
in TABLE 3, to prepare differ.RTM.nt solutions, and an attempt was made to 
obtain films through the same steps as in EXAMPLE 11. 
TABLE 3 
__________________________________________________________________________ 
EXAMPLES 
11 12 
13 
14 15 16 17 18 19 20 21 
__________________________________________________________________________ 
(1) 
PPO (g) 
120 
80 
70 
20 40 60 100 
160 
110 
80 175 
(2) 
PS (g) 
40 80 
70 
140 
120 
40 90 20 10 10 5 
(3) 
TAIC (g) 
40 40 
60 
40 40 100 
10 20 80 110 
20 
__________________________________________________________________________ 
COMATIVE EXAMPLES 
7 8 9 10 11 
__________________________________________________________________________ 
(1) 200 40 190 40 10 
(2) 0 0 5 20 120 
(3) 0 160 5 140 70 
__________________________________________________________________________ 
The obtained compositions were observed and tested in respect to the 
presence or absence of the film-forming property, homogeneity, surface 
tackiness and tensile strength, results of which are given in TABLE 4 
below. In the Table, the mark "X" indicates excellent and hyphen "-" 
indicates unmeasurable. 
TABLE 4 
__________________________________________________________________________ 
EXAMPLES 
11 12 13 14 15 16 17 18 19 20 21 
__________________________________________________________________________ 
(1) 
Film-form. prop. 
X X X X X X X X X X X 
(2) 
Homogeneity 
X X X X X X X X X X X 
(3) 
Surfce tack. 
X X X X X X X X X X X 
(4) 
Tensile streng. 
500 
500 
450 
250 
350 
300 
450 
300 
200 
150 
250 
(Kgf/cm.sup.2) 
__________________________________________________________________________ 
COMATIVE EXAMPLES 
7 8 9 10 
11 
__________________________________________________________________________ 
(1) no no 
no no 
no 
(2) -- -- 
-- -- 
X 
(3) -- -- 
-- -- 
no 
(4) -- -- 
-- -- 
-- 
__________________________________________________________________________ 
As will be clear in view from FIG. 2, wherein circular dots represent the 
composition ratios of EXAMPLES 11 to 21 and square dots represent those of 
COMATIVE EXAMPLES 7 to 11, it has been found that the composition 
ratios of PPO, PS and TAIC used in EXAMPLES 11 to 21 reach favorable 
results, while the composition ratios of COMATIVE EXAMPLES which are 
outside the zone C2 in FIG. 2 do not provide any favorable composition 
films. 
According to a third feature of the present invention, PPO, STP and TAIC 
(and/or TAC) were mixed to provide a film-forming property and obtain a 
PPO composition. The same PPO and STP as those in the foregoing EXAMPLES 1 
to 10 can be used, and the same TAIC (and/or TAC) as those in the above 
EXAMPLES 11 to 21 can be used. 
Referring next to the triangular diagram of FIG. 3 of various composition 
ratios of PPO, STP and TAIC respectively taken on each side of the system, 
favorable PPO compositions can be obtained in a zone C3, shaded with 
rightward upward hatches, in which PPO is present in an amount above 7 and 
below 93 weight STP is present in an amount above 7 and below 93 weight %, 
and TAIC (and/or TAC) is present in an amount below 70 weight %, more 
preferred PPO compositions can be obtained in a zone D3, located within 
the zone C3 and shaded with leftward upward hatches, and most preferred 
PPO compositions can be obtained in a zone E3, located inside the zone D3 
and shaded with vertical hatches, wherein PPO is present in an amount 
above 10 and below 80 weight STP is present in an amount from 20 to 80 
weight % and TAIC (and/or TAC) is present in an amount below 60 weight %. 
The solvent used in mixing the three of PPO, STP and TAIC (and/or TAC) may 
be the same as that explained in connection with the first feature, and 
the film formation can be performed by means of substantially the same 
casting process as explained also in connection with the first feature. 
EXAMPLE 22 
In a reactor having a defoamer and of a capacity of 2 liters, a solution of 
110 g of PPO, 80 g of styrene-butadiene-block copolymer (SBS) as STP and 
10 g of TAIC with 800 g of TCE was prepared, and a PPO composition film of 
about 100 .mu.m thick was obtained through the same steps as in EXAMPLE I. 
EXAMPLE 23 to 34 
The composition ratio of PPO, STP and TAIC was varied as shown in the 
following TABLE 5 to obtain different PPO composition films through the 
same steps as in EXAMPLE 22. 
COMATIVE EXAMPLES 12 to b 16 
The composition ratio of PPO, STP and TAIC was varied as shown also in 
TABLE 5 to prepare different solutions, and an attempt was made to obtain 
films through the same steps as in EXAMPLE 22. 
TABLE 5 
__________________________________________________________________________ 
EXAMPLES 
22 23 24 25 26 27 28 29 30 31 32 
33 34 
__________________________________________________________________________ 
(1) 
PPO (g) 
110 
40 120 
40 40 20 40 20 50 170 
90 
180 
25 
(2) 
STP (g) 
80 150 
40 120 
40 160 
20 175 
20 20 30 
15 40 
(3) 
TAIC (g) 
10 10 40 40 120 
20 140 
5 130 
10 80 
5 135 
__________________________________________________________________________ 
COMATIVE EXAMPLES 
12 13 14 15 16 
__________________________________________________________________________ 
(1) 200 80 10 160 20 
(2) 0 0 160 10 20 
(3) 0 120 30 30 160 
__________________________________________________________________________ 
The obtained compositions were observed and tested in respect to the 
presence or absence of film-forming property, homogeneity, surface 
tackiness and tensile strength, the results of which are given in the 
following TABLE 6, in which the marks "X" and "-" indicate excellent and 
unmeasurable states, respectively. 
TABLE 6 
__________________________________________________________________________ 
EXAMPLES 
22 23 24 25 26 27 28 29 30 31 32 33 34 
__________________________________________________________________________ 
(1) 
Film-form. 
X X X X X X X X X X X X X 
prop. 
(2) 
Homogeneity 
X X X X X X X X X X X X X 
(3) 
Surface 
X X X X X X X X X X X X no 
tack. 
(4) 
Tensile 
450 
300 
400 
350 
200 
150 
100 
150 
150 
400 
300 
350 
150 
Streng. 
(Kgf/cm.sup.2) 
__________________________________________________________________________ 
COMATIVE EXAMPLES 
12 13 
14 15 
16 
__________________________________________________________________________ 
(1) no no 
no no 
no 
(2) -- -- 
-- -- 
-- 
(3) -- -- 
-- -- 
-- 
(4) -- -- 
-- -- 
-- 
__________________________________________________________________________ 
As will be clear in view of FIG. 3, in which circular dots represent the 
composition ratios of EXAMPLES 22 to 34 and square dots represent those of 
COMATIVE EXAMPLES, it is found that the composition ratios of PPO, STP 
and TAIC used in EXAMPLES 22-34 result in favorable compositions, while 
the ratios of COMATIVE EXAMPLES which are outside the zone C3 in FIG. 3 
never provide favorable films. 
According to a fourth feature of the present invention, PB is further added 
to and mixed with the solution of PPO, STP and TAIC (and/or TAC) of the 
third feature, to provide a film-forming property and obtain a PPO 
compound. PB may be the one used in EXAMPLES 1 to 10. According to this 
feature, a favorable PPO compound can be obtained when PPO is present in 
an amount above 10 and below 90 weight %, STP is present in an amount 
above 10 and below 90 weight %, TAIC (and/or TAC) is present in an amount 
less than 80 weight % and PB is present in an amount below 20 weight %, 
and most preferred PPO composition films can be obtained when PPO is 
present in an amount above 30 and below 80 weight %, STP is present in an 
amount above 20 and below 70 weight %, TAIC (and/or TAC) is present in an 
amount less than 50 weight % and PB is present in an amount below 10 
weight %. 
The solvent used in mixing PPO, STP and TAIC (and/or TAC) may be the same 
as that explained in connection with the first feature, and the casting 
referred to with reference also to the first feature may be carried out 
substantially through the same steps for forming the film. 
EXAMPLE 35 
In a reactor having a defoamer and of a capacity of 2 liters, 100 g of PPO, 
40 g of SBS as STP, 40 g of TAIC and 20 g of PB were mixed with 800 g of 
TCE to obtain a PPO composition film of 100 .mu.m thick through the same 
steps as in EXAMPLE I. 
EXAMPLES 36 to 45 
The composition ratios of PPO, STP, TAIC and PB were changed as shown in 
the following TABLE 7 to obtain different PPO composition films through 
the same steps as in EXAMPLE 35. 
COMATIVE EXAMPLES 17 to 23 
The composition ratios of PPO, STP, TAIC and PB were changed as shown also 
in TABLE 7, to prepare different solutions in an attempt to obtain films 
through the same steps as in EXAMPLE 35. 
TABLE 7 
__________________________________________________________________________ 
EXAMPLES 
35 36 37 38 39 40 
41 42 43 
44 45 
__________________________________________________________________________ 
(1) 
PPO (g) 
100 
100 
110 
120 
80 80 
130 
115 
40 
25 20 
(2) 
STP (g) 
40 60 40 40 100 
20 
30 45 80 
25 150 
(3) 
TAIC (g) 
40 20 40 20 15 80 
25 10 65 
140 
10 
(4) 
PB (g) 
20 20 10 20 5 20 
15 30 15 
10 20 
__________________________________________________________________________ 
COMATIVE EXAMPLES 
17 18 19 20 21 22 23 
__________________________________________________________________________ 
(1) 
200 20 85 10 100 40 190 
(2) 
0 20 45 100 
10 40 10 
(3) 
0 20 10 80 70 120 0 
(4) 
0 140 60 10 20 0 0 
__________________________________________________________________________ 
The obtained compositions were observed and tested in respect of the 
presence or absence of film-forming property, homogeneity, surface 
tackiness and tensile strength. The results are given in TABLE 8 below, in 
which marks "X" and "-" represent excellent and unmeasurable states, 
respectively. 
TABLE 8 
__________________________________________________________________________ 
EXAMPLES 
35 36 37 38 39 40 41 42 43 44 45 
__________________________________________________________________________ 
(1) 
Film-form. 
X X X X X X X X X X X 
prop. 
(2) 
Homogeneity 
X X X X X X X X X X X 
(3) 
Surface 
X X X X X X X X X no X 
tack. 
(4) 
Tensile 
400 
400 
400 
400 
400 
350 
400 
300 
250 
100 
250 
streng. 
(Kgf/cm.sup.2) 
__________________________________________________________________________ 
COMATIVE EXAMPLES 
17 18 
19 20 
21 22 
23 
__________________________________________________________________________ 
(1) no no 
X X no no 
no 
(2) -- -- 
no X -- no 
no 
(3) -- -- 
no no 
-- no 
no 
(4) -- -- 
-- -- 
-- -- 
-- 
__________________________________________________________________________ 
It will be seen from TABLE 8 that the composition ratios of PPO, STP, TAIC 
and PB used in EXAMPLES 35 to 45 result in favorable PPO composition, 
while those used in COMATIVE EXAMPLES 17 to 23 do not result in any 
favorable compositions. 
According to a fifth feature of the present invention, PPO, PS and PB are 
mixed to obtain PPO compositions having the film-forming property. Here, 
PPO and PB may be the same as those used in EXAMPLES 1 to 10, and PS may 
be that used in EXAMPLES 11 to 21. 
Referring to FIG. 4, a triangular diagram showing the composition ratios of 
PPO, PS and PB which are taken respectively on each of three sides of the 
diagram, it will be seen that favorable PPO compositions can be obtained 
in a zone C4, shaded with rightward upward hatches, wherein PPO is present 
in an amount above 8 and below 90 weight %, PS is present in an amount 
above 10 and below 92 weight % and PB is present in an amount below 24 
weight %; that more preferred PPO compositions can be obtained in a zone 
D4, located inside the zone C4 and shaded with leftward upward hatches, 
and that most preferred PPO composition films can be obtained in a zone 
E4, located inside the zone D4 and shaded with vertical hatches wherein 
PPO is present in an amount above 30 and below 80 weight %, PS is present 
in an amount above 20 and below 70 weight % and PB is present in an amount 
below 10 weight %. 
The solvent used in mixing PPO, PS and PB may be the same as that explained 
in connection with the first feature, and the casting explained also in 
connection with the first feature may be employed for forming the films as 
carried out substantially through the same steps. 
EXAMPLE 46 
In the reactor having a defoamer and of a capacity of 2 liters, 80 g of 
PPO, 110 g of PS and 10 g of PB were mixed with 800 g of TCE, and a PPO 
composition film of about 100 .mu.m thick was obtained through the same 
steps as in EXAMPLE 1. 
EXAMPLES 47 to 56 
The composition ratios of PPO, PS and PB were changed as shown in the 
following TABLE 9, and different PPO composition films were obtained 
through the same steps as in EXAMPLE 46. 
COMATIVE EXAMPLES 24 to 29 
The composition ratios of PPO, PS and PB were changed as shown also in 
TABLE 9 to prepare different solutions, and an attempt was made to obtain 
films also through the same steps as in EXAMPLE 46. 
TABLE 9 
__________________________________________________________________________ 
EXAMPLES 
46 47 48 49 50 51 
52 53 54 55 56 
__________________________________________________________________________ 
(1) 
PPO (g) 
80 100 
140 
40 40 80 
20 120 
25 20 170 
(2) 
PS (g) 
110 
80 50 150 
120 
80 
160 
35 170 
135 
20 
(3) 
PB (g) 
10 20 10 10 40 40 
20 45 5 45 10 
__________________________________________________________________________ 
COMATIVE EXAMPLES 
24 25 26 27 28 29 
__________________________________________________________________________ 
(1) 200 10 160 50 120 
20 
(2) 0 170 10 90 20 0 
(3) 0 20 30 60 60 80 
__________________________________________________________________________ 
The obtained compositions were observed and tested in respect of the 
presence or absence of film-forming property, homogeneity, surface 
tackiness and tensile strength. The results are given in TABLE 10 below, 
in which marks "X" and "-" represent excellent and unmeasureable states, 
respectively. 
TABLE 10 
__________________________________________________________________________ 
EXAMPLES 
46 47 48 49 50 51 52 53 54 55 56 
__________________________________________________________________________ 
(1) 
Film-form. 
X X X X X X X X X X X 
prop. 
(2) 
Homogeneity 
X X X X X X X X X X X 
(3) 
Surface X X X X X X X X X X X 
tack. 
(4) 
Tensile 300 
350 
350 
250 
300 
350 
200 
300 
200 
200 
300 
streng. 
(Kgf/cm.sup.2) 
__________________________________________________________________________ 
COMATIVE EXAMPLES 
24 
25 26 
27 28 
29 
__________________________________________________________________________ 
(1) no 
X no 
X X no 
(2) -- 
no -- 
no no 
no 
(3) -- 
X -- 
no no 
no 
(4) -- 
-- -- 
-- -- 
-- 
__________________________________________________________________________ 
In view of FIG. 4, in which the composition ratios of EXAMPLES 46 to 56 are 
plotted by circular dots and those of COMATIVE EXAMPLES 24-29 are 
plotted by square dots, it is found that the favorable PPO composition 
films can be obtained with the composition ratios of PPO, PS and PB in 
EXAMPLES 46 to 56, whereas no favorable PPO composition film were obtained 
using the ratios of COMATIVE EXAMPLES 24-29, which are outside the zone 
C4 in FIG. 4. 
According to the foregoing first to fifth features of the present 
invention, there has been provided a method in which PPO is mixed with at 
least one crosslinking polymer and/or crosslinking monomer as a setting 
means that includes polyfunctional components. According to a sixth 
feature of the present invention, PPO is mixed with at least one 
crosslinking polymer and/or monomer and an initiator. A PPO composition 
that exhibits excellent film-forming properties, solvent resistance, heat 
resistance and strength is thereby obtained. 
Referring to the sixth feature, the foregoing STP and PB are preferably 
used as the crosslinking polymers, but one or a mixture of two or more 
rubbers may be also used. As the crosslinking monomers, for example, other 
polyfunctional monomers than TAIC and TAC may be used such as ethylene 
glycol dimethacrylate, divinylbenzene, diallyl phthalate and the like, 
such acrylic acids as ester acrylate, epoxy acrylate, urethane acrylate, 
ether acrylate, melamine acrylate, alkyl acrylate, silicon acrylate and 
the like, such monofunctional monomers as vinyltoluene, ethyl vinyl 
benzene, stryene, paramethylstyrene and the like, and mixtures of such 
polyfunctional monomers. 
For the initiator, such organic peroxides as di-cumyl peroxide, t-butyl 
cumyl peroxide, di-t-butyl peroxide, ketone peroxide, peroxyketal, 
hydroperoxide, dialkyl peroxide, diacyl peroxide, peroxydicarbonate, 
peroxyesther and the like may be employed. Further, one or more peroxides 
selected from the group consisting of those compounds represented by 
following structural formulas (I), (II) and (III) may also be employed: 
##STR2## 
where R represents a hydrocarbon radical and R' and R" represent a 
hydrocarbon radical or a hydrogen, and R, may be the same as or different 
from R". 
The peroxides expressed by formula (I) include, for example, 
2,2-bis-t-butyl-peroxyoctane, n-butyl-peroxyvalerate, 
2,2-bis-t-butyl-peroxybutane, 2,5-dimethyl-hexane-2,5-dihydro-peroxide, 
2,2'-bis-t-butyl-peroxy-m-isopropyl-benzene (also known as (1,4 or 
1,3)-bis-t-butyl-peroxyisopropyl-benzene)), 
2,5-dimethyl-2,5-di-t-butyl-peroxyhexane, 
2,5-dimethyl-2,5-di-t-butyl-peroxyhexane-3 and the like. The compounds 
expressed by formula (II) include, for example, 
2,5-dimethyl-2,5-di-benzoylperoxyhexane and the like. The compounds 
expressed by formula (III) include, for example, 
di-t-butyl-peroxyisophthalate and the like. Among these peroxides listed 
above, in particular, 2,5-dimethyl-2,5-di-t-butyl-peroxyhexane-3 and 
.alpha.,.alpha.-bis-t-butyl-peroxy-m-isopropyl-benzene of formula (I) are 
preferred. 
When the initiator used in the present feature is the peroxide expressed 
by, for example, formula (I), the crosslinking property can be further 
enhanced by the application of external physical action as, for example, 
heating and irradiation of ultraviolet or radioactive ray, which causes 
O--O coupling in the initiator to be cut. That is, 
EQU R'--O--O--R--O--O--R".fwdarw.R'--.+.O--R--O.+.O--R" 
to cause radical reaction to take place, which reaction further proceeds as 
##STR3## 
According to this sixth feature, it has been found that the desired PPO 
composition can be obtained when PPO is present in an amount from 50 to 95 
weight %, the crosslinking polymer and/or crosslinking monomer is present 
in an amount from 5 to 50 weight and the initiator is present in an amount 
from 0.1 to 5.0 weight %. The solvent used in mixing them may be the same 
as explained in connection with the first feature, and the film formation 
may also be carried out by casting substantially through the same steps as 
in the case of the first feature. 
According to a seventh feature of the present invention a method of 
manufacturing a laminate using the PPO compositions is provided. In this 
case, PPO, crosslinking polymer and/or crosslinking monomer are used in 
preparing the PPO composition film for the manufacture of the laminate, 
wherein PPO may be the same as used in EXAMPLES 1 to 10, and the 
crosslinking polymer and/or the crosslinking monomer may be the same as 
those detailed in connection with the sixth feature. If an initiator is 
employed, it is also possible to use an initiators, other than the organic 
peroxides such as BISCUMYL, a product available from the Japanese firm 
NIPPON YUSHI KABUSHIKI KAISHA having the following structure (hereinafter 
referred to as "BC"): 
##STR4## 
BC has a one-minute half-life temperature of 330.degree. C. 
In mixing PPO with the crosslinking polymer and/or crosslinking monomer 
and, if desired, the initiator, the same solvent as that explained in 
connection with the first feature may be used and, in forming the films, 
the casting may be carried out substantially through the same steps as in 
the case of the first feature. 
According to a predetermined laminate design, an appropriate number of the 
PPO composition films, as well as such metallic foils as copper, aluminum 
or the like, are properly stacked and preferably heat-pressed so that the 
films will melt to bond with each other and with the metallic foils so as 
to form a laminate. In this case, the heat-press temperature is set 
depending on the reaction temperature of the initiator, and is usually 
within a range of about 150.degree. to 300.degree. C. The heat-press 
pressure and time are also to be appropriately set, and are preferable 
under 50 Kg/cm.sup.2 for 10 to 60 minutes. It is possible to add to such a 
laminate a further metallic foil as overlaid onto one or both surfaces of 
the laminate and bonded thereto through a further carried out hot-press 
step. 
EXAMPLES 57 
In a 2 liter reactor having a defoamer, 120 g of PPO, 40 g of SBS, 18 g of 
1,2 PB, 20 g of TAIC and 2 g of BC were mixed by adding TCE until a 
solution of 30 weight % was obtained. PPO composition films of 100 .mu.m 
thick were obtained substantially through the same steps as in EXAMPLE 1. 
Then, ten of these prepared films were stacked and pressed to be of a 
dimension of 200.times.200 mm, a copper foil of 35 .mu.m thick was placed 
on each of the upper and lower surfaces of the laminate, heat-press was 
carried out at a temperature of 240.degree. C. and under a pressure of 50 
Kg/cm.sup.2 for 30 minutes with respect to the laminate, and a both-faced 
copper-clad laminate was obtained. 
EXAMPLES 58 to 66 
The composition ratios of PPO, SBS, PB and TAIC were varied as shown in the 
following TABLE 11 with a suitable initiator (INIT) selected and added, 
and different PPO composition films were formed into different laminates 
through the same steps as in EXAMPLE 57. 
COMATIVE EXAMPLES 30 and 31 
The composition ratio of the materials of EXAMPLE 57 was varied as shown in 
TABLE 11, as COMATIVE EXAMPLES 30 and 31, in an attempt to obtain PPO 
composition laminates through the same steps as in EXAMPLE 57. 
TABLE 11 
__________________________________________________________________________ 
COMATIVE 
EXAMPLES EXAMPLES 
57 58 59 60 61 62 63 64 65 66 30 31 
__________________________________________________________________________ 
PPO (g) 
120 
120 120 
120 
120 
120 
120 
140 
160 
140 
188 172 
SBS (g) 
40 40 40 40 40 40 40 38 18 48 10 -- 
1,2PB (g) 
18 18 18 18 18 18 18 -- -- -- -- 8 
TAIC (g) 
20 20 20 20 20 20 20 20 20 10 -- -- 
INIT (g) 
BC2 
DCP2 
F2 G2 H2 I2 J2 H2 H2 H2 H2 I20 
__________________________________________________________________________ 
On the line of the initiator (INIT) in the above TABLE 11, DCP is dicumyl 
peroxide, F is t-butylcumyl-peroxide, G is di-t-butyl-peroxide, H is 
2,5-dimethyl-2,5-di-t-butyl-peroxyhexane-3, I is 
2,5-dimethyl-2,5-di-t-butyl-peroxyhexane, and J is 
.alpha.,.alpha.'-bis-t-butyl-peroxy-m-isopropyl-benzene. 
TABLE 12 shows the results of tests made on the obtained laminates in 
respect of (I) the room temperature peeling-strength, (II) soldering heat 
resistance, (III) insulation resistance, (IV) dielectric constant and (V) 
dielectric loss tangent, in which hyphens "-" indicate an unmeasurable 
state: 
TABLE 12 
__________________________________________________________________________ 
EXAMPLES 
57 58 59 60 61 62 63 64 65 66 
__________________________________________________________________________ 
(I) (Kg/cm) 
1.5 
1.8 
1.8 
1.8 
1.8 
1.8 
1.8 
1.8 
2.0 
2.0 
(II) (sec) 
20 30 60 60 60 60 60 60 60 30 
(III) (.OMEGA.) 
10.sup.15 
10.sup.15 
10.sup.15 
10.sup.15 
10.sup.15 
10.sup.15 
10.sup.15 
10.sup.15 
10.sup.15 
10.sup.15 
(IV) (9 GHz) 
2.6 
2.6 
2.6 
2.6 
2.6 
2.6 
2.6 
2.6 
2.6 
2.4 
(V) (9 GHz) 
0.003 
0.003 
0.003 
0.003 
0.003 
0.003 
0.003 
0.003 
0.003 
0.002 
__________________________________________________________________________ 
COMATIVE EXAMPLES 
30 
31 
__________________________________________________________________________ 
(I) (kg/cm) -- 
-- 
(II) (sec) -- 
-- 
(III) (.OMEGA.) 
-- 
-- 
(IV) (9 GHz) -- 
-- 
(V) (9 GHz) -- 
-- 
__________________________________________________________________________ 
It can be seen that the metal-load laminates of EXAMPLES 57 to 66 are 
extremely excellent in the room temperature peeling-strength, soldering 
heat resistance and insulation resistance, fairly excellent in the 
dielectric constant and dielectric loss tangent based on the U.S. Military 
Specification and Standard (MIL), excellent in high frequency 
characteristics, and thus suitable for use in such superhigh frequency 
bands as the X band. 
According to an eighth feature of the present invention, a step of 
irradiating the laminates with a radioactive ray may be added to the 
foregoing seventh feature so as to maintain the dielectric characteristics 
and to remarkably improve the room temperature peeling-strength and 
soldering heat resistance. In the case of this feature, PPO and 
crosslinking polymer and/or crosslinking monomer are used in making the 
PPO composition films for the preparation of laminate, as in the case of 
the seventh feature. PPO may be the same as used in the foregoing EXAMPLES 
1 to 10, while the crosslinking polymer and/or monomer may be the ones 
that exhibit a good crosslinking property when exposed to the irradiation. 
Such materials as disclosed in connection with the sixth feature may be 
also used as the crosslinking polymer and/or monomer. It is also possible 
to use poly-para-methylstyrene among the crosslinking resins or polymers 
disclosed in connection with the sixth feature, and TAIC among the 
crosslinking assistants or monomers disclosed also in connection with the 
sixth feature, in improving the crosslinking property by means of the 
irradiation. It has been found that TAIC increases the crosslinking degree 
up to 90% when exposed to 50 Mrad irradiation. The initiators explained in 
connection with the sixth feature and BC explained in connection with the 
seventh feature may be used concurrently. Other than such initiators as 
explained in the sixth feature, i.e., the organic peroxides, there may be 
enumerated as the initiator, benzoin, benzyl, allyldiazonium fluoroborate, 
benzylmethylketal, 2,2-diethoxyacetophenone, benzoyl isobutyl ether, 
p-t-butyl-trichloroacetophenone, 
benzyl-o-ethoxy-carbonyl-.alpha.-monooxime, biacetyl, acetophenone, 
benzophenone, tetramethylthiuram sulfide, azobisisobutyronitril, benzoyl 
peroxide, 1-hydroxycyclohexyl phenylethane, 
2-hydroxy-2-methyl-1-phenylpropane-1-one, 
1-(4-isopropylphenyl)-2-hydroxy-2-methylpropane-1-one, 
2-chlorothioxanthone, methylbenzoyl formate, 
4,4-bis-dimethyl-amino-benzophenone (Michler's ketone), 
benzoin-methyl-ether, methyl-o-benzoyl-benzoate, .alpha.-acyloxime ester, 
and the like. 
In mixing PPO with the crosslinking polymer and/or crosslinking monomer 
with the addition, if necessary, of the initiator, similarly to the 
foregoing features, the same solvent as explained in connection with the 
first feature may be employed to prepare a solution, and the film 
formation may be carried out by means of the casting substantially through 
the same steps as disclosed in connection with the first feature. 
The required number for a predetermined laminate design thickness of such 
films thus obtained and such metallic foils as copper or aluminum foils 
were properly sequentially stacked, and processed through the same steps 
as in the seventh feature into the metal-clad laminate of the design 
thickness of, for example, 0.2 to 2.0 mm, preferably about 0.6 to 0.8 mm, 
and suitable for a circuit design. Subsequentially the laminate was 
exposed to an irradiation (.beta. ray, .gamma. ray or the like) by an 
amount of 10 to 70 Mrad, preferably 40 to 60 Mrad, according to the 
composition ratio of the macromolecular materials employed, so as to 
induce the thermal melting and bonding property of PPO, to increase the 
crosslinking property at the bonding boundary surfaces between the films 
and the metallic foils, and to thereby complete the metal-clad laminate. 
EXAMPLES 67 to 76 
Each of the laminates prepared in the EXAMPLES 57 to 66 was exposed to 30 
Mrad irradiation (of .beta.ray). 
The thus obtained metal-clad laminates were tested in respect of (I) the 
room temperature peeling-strength, (II) soldering heat resistance, (III) 
insulation resistance, (IV) dielectric constant and (V) dielectric loss 
tangent. Results of such tests are given in TABLE 13. 
TABLE 13 
__________________________________________________________________________ 
EXAMPLES 
67 68 69 70 71 72 73 74 75 76 
__________________________________________________________________________ 
(I) (Kg/cm) 
2.4 
2.5 
2.5 
2.5 
2.5 
2.5 
2.5 
2.5 
2.5 
2.5 
(II) (sec) 
40 60 90 90 90 90 90 90 90 90 
(III) (.OMEGA.) 
10.sup.15 
10.sup.15 
10.sup.15 
10.sup.15 
10.sup.15 
10.sup.15 
10.sup.15 
10.sup.15 
10.sup.15 
10.sup.15 
(IV) (9 GHz) 
2.6 
2.6 
2.6 
2.6 
2.6 
2.6 
2.6 
2.6 
2.6 
2.4 
(V) (9 GHz) 
0.003 
0.003 
0.003 
0.003 
0.003 
0.003 
0.005 
0.003 
0.003 
0.002 
__________________________________________________________________________ 
As can be seen from comparison between TABLES 13 and 12 that, according to 
the present feature, the room temperature peeling-strength and soldering 
heat resistance of the laminates can be remarkably improved, while the 
insulation resistance, dielectric constant and dielectric loss tangent 
remain substantially unchanged so as to maintain the excellent dielectric 
characteristics. 
According to a ninth feature, PPO, TAIC (and/or TAC) are used as basic 
materials to obtain the laminate of the PPO composition films. PPO may be 
the same as in EXAMPLES 1 to 10 and TAIC (and/or TAC) may be the same as 
explained in connection with the second feature. In the present feature, 
it is desirable that PPO be present in an amount from 50 to 95 weight % 
and TAIC (and/or TAC) be present in an amount from 5 to 50 weight %. In 
mixing these materials, 0.1 to 5.0 weight % of an initiator is preferably 
added and mixed therewith. 
For the purpose of improving the film-forming property, it is further 
preferable to add to this mixture PB. 
In mixing these materials, the same solvent as explained in connection with 
the first feature may be used. Even a mere mixing may be sufficient. The 
films may be formed by means of the casting performed substantially 
through the same steps as explained in connection with the first feature. 
A required number of the films thus obtained and metallic foils are 
stacked to a predetermined laminate design thickness and processed through 
the same steps as in the seventh feature into a metalclad laminate having 
a thickness of preferably 0.6 to 0.8 mm, and suitable for a circuit 
design. 
In forming the laminate, if desired, it may be possible to employ even a 
resin-impregnated substrate, which may be glass cloth, glass mat, 
polyester cloth, aramid fiber cloth, paper, unwoven cloth or the like, 
impregnated with a resin solution containing PPO, TAIC (and/or TAC) and, 
if necessary, an initiator and/or PB and dried. The impregnation may be 
made alternatively with a solution containing such other material than PB 
as the crosslinking polymer and/or monomer disclosed in the sixth feature, 
added to PPO, TAIC (and/or TAC) and, if necessary, an initiator, the 
solution being also dried. 
In forming the laminate with such a resin-impregnated substrate, a required 
number of the PPO composition films and metallic foils for a predetermined 
design thickness of the laminate are stacked on the substrate, a stack 
thus obtained is heat-pressed so that the resin-impregnated substrate, PPO 
composition films and metallic foils will be mutually firmly bonded, with 
the adhesion of PPO being utilized, and the desired metal-clad laminate 
will be obtained. In this case, the heatpress temperature is set depending 
on the reaction temperature of the initiator, usually within a range of 
150.degree. and 300.degree. C., while the pressure and time are set 
preferably to be 10 to 150 Kg/cm.sup.2 and for about 10 to 90 minutes. 
EXAMPLE 77 
180 g of PPO, 170 g of SBS, 650 g of TAIC, 20 g of 
2,5-dimethyl-2,5-di-t-butyl-peroxyhexane-3 (PH25B) and 3000 g of TCE were 
mixed while being heated to 50.degree. C. in a container having an 
agitator until completely dissolved and a resin solution was obtained A 
glass cloth of E glass 100 .mu.m thick (104.5 g/m.sup.2) was immersed into 
the resin solution and was dried at 70.degree. C. for 5 minutes. A prepreg 
having a resin content of 50% was then prepared. 
Six of the above prepregs were stacked with copper foils of 18 .mu.m, the 
stack was heated and compressed by means of a laminating press at 
200.degree. C. under 10 kg/cm.sup.2 for 40 minutes, and a laminate of a 
thickness of 0.8 mm and both of its outermost surfaces being copper-clad 
was obtained. Various properties of this laminate are as shown in Table 
14. 
EXAMPLE 78 
250 g PPO, 250 g SBS, 500 g TAIC, 20 g PH25B and 3000 g TCE were employed 
and a laminate, both of its outermost surfaces being copper-clad, was 
prepared in the same manner as in EXAMPLE 77. The properties of the 
laminate are as shown in Table 14. 
EXAMPLE 79 
330 g PPO, 320 g SBS, 250 g TAIC, 20 g PH25B and 3000 g TCE were employed 
and a laminate, both of its outermost surfaces being copper-clad, was 
prepared in the same manner as in EXAMPLE 77. The properties of the 
laminate are as shown in Table 14. 
TABLE 14 
______________________________________ 
EX- EX- EX- 
AMPLE 77 
AMPLE 78 AMPLE 79 
______________________________________ 
Specific 
Inductivity 3.5 3.4 3.4 
(1 MHz) 
Dielectric 
Loss(1 MHz) 0.003 0.003 0.0025 
Soldering 
Heat (260.degree. C.) Bef. PCT 
120&lt; 120&lt; 120&lt; 
Resist. (sec.) Aft. PCT 
60&lt; 60&lt; 60&lt; 
Oven Heat 
Resist. (.degree.C.) 
280 280 280 
Solvent 
Resist. (boiled TCE) 
Good Good Good 
Volume 
Resistivity (.OMEGA.-cm) 
5 .times. 10.sup.15 
5 .times. 10.sup.15 
5 .times. 10.sup.15 
Insulation 
Resistance (.OMEGA.) 
5 .times. 10.sup.14 
7 .times. 10.sup.14 
7 .times. 10.sup.14 
Water Absorption (%) 
0.20 0.15 0.15 
______________________________________ 
The laminate including resin-impregnated substrate and prepared in the 
above-mentioned manner can be exposed to heat and/or an irradiation of 
ultraviolet light or radioactive ray (.beta. or .gamma. ray), and radical 
reaction takes place so as to enhance the hardening of the laminate. 
In preparing the metal-clad laminate, it is not always necessary to stack 
the metallic foils simultaneously with the film. 
EXAMPLE 80 
In the reactor having the defoamer, 140 g of PPO, 60 g of TAIC and 4 g of 
2,5-dimethyl-2, 5-t-butyl-peroxyhexane-3 as the initiator were mixed by 
adding TCE until the mixture became a solution of 20 weight %. PPO 
composition films of 100 .mu.m thick were obtained substantially through 
the same steps as in the foregoing EXAMPLES. Six of such films were 
stacked and heat-pressed at a temperature of 200.degree. C., under a 
pressure of 50 Kg/cm.sup.2 and for 30 minutes, and a laminate of 0.8 mm 
thick was obtained. 
EXAMPLE 81 
160 g of PPO, 40 g of TAIC and 2 g of 
2,5-dimethyl-2,5-di-t-butylperoxyhexane-3 as the initiator were mixed by 
adding TCE until the mixture became a 15 weight % solution. This solution 
was used in having a glass cloth impregnated therewith to form through 
drying a resin-impregnated substrate. Thereafter, a copper foil, three of 
the thus obtained resin-impregnated substrates and a copper foil were 
stacked in the order mentioned and heat-pressed at a temperature of 
200.degree. C., under a pressure of 50 Kg/cm.sup.2 and for 30 minutes so 
as to be formed into a laminate of 0.8 mm thick. 
EXAMPLE 82 
The composition ratio of EXAMPLE 80 was changed to 100 g of PPO, 100 g of 
TAIC, and 4 g of .alpha.,.alpha.-bis-t-butylperoxy-m-isopropyl benzene as 
the initiator, and a laminate similar to that of EXAMPLE 80 was obtained 
substantially through the same steps. 
EXAMPLE 83 
The composition ratio of EXAMPLE 81 was changed to 180 g of PPO, 20 g of 
TAIC, and 2 g of 2,5-dimethyl-2,5-t-butylperoxyhexane-3 as the initiator, 
to obtain a laminate including the resin-impregnated substrates similar to 
that of EXAMPLE 81 substantially through the same steps. 
EXAMPLE 84 
The composition ratio of EXAMPLE 80 was changed to 140 g of PPO, 40 g of 
TAIC, 20 g of 1,2-PB, and 4 g of 2,5-dimethyl-2,5-t-butylperoxyhexane-3 to 
form the PPO composition films, 15 sheets of which were stacked and 
heat-pressed under a pressure of 100 Kg/cm.sup.2, but without changing 
other conditions of the steps of EXAMPLE 80 for forming the laminate 
thereof. 
EXAMPLE 85 
The composition ratio of EXAMPLE 81 was changed to 120 g of PPO, 40 g of 
TAIC, 40 g of 1,2-PB, and 2 g of 
.alpha.,.alpha.'-bis-t-butylperoxy-m-isopropylbenzene as the initiator, 
and a laminate including the resin-impregnated substrates similar to that 
of EXAMPLE 81 was obtained through a heat-press process that used a 
temperature and time of 200.degree. C. and 60 minutes, respectively, but 
without changing the other conditions. 
EXAMPLE 86 
The composition ratio of EXAMPLE 80 was changed to 160 g of PPO, 20 g of 
TAIC, 20 g of 1,2-PB, and 2 g of an initiator, and a laminate similar to 
that of EXAMPLE 80 was obtained substantially through the same steps. 
The thus obtained laminates of EXAMPLES 80 to 86 were tested in respect of 
(I) the room temperature peeling-strength, (II) soldering heat resistance, 
(III) insulation resistance, (IV) dielectric constant and (V) dielectric 
loss tangent. The results are given in TABLE 15 as follows: 
TABLE 15 
______________________________________ 
EXAMPLES 
80 81* 82 83* 84 85* 86 
______________________________________ 
(I) (Kg/cm) 
2.0 2.5 2.0 2.5 2.0 2.5 2.0 
(II) (sec) 
60 &gt;120 60 &gt;120 90 &gt;120 90 
(III) (.OMEGA.) 
10.sup.15 
10.sup.15 
10.sup.15 
10.sup.15 
10.sup.15 
10.sup.15 
10.sup.15 
(IV) 2.6 3.0 2.65 2.95 2.6 2.9 2.55 
(10 GHz) 
(V) (10 GHz) 
0.003 0.004 0.003 
0.003 0.003 
0.003 0.002 
______________________________________ 
From comparisons of TABLE 15 with TABLES 12 and 13, it will be appreciated 
that the room temperature peeling-strength, soldering heat resistance and 
dielectric characteristics remained excellent. Regarding the soldering 
heat resistance the test for which has been carried out throughout the 
seventh to the ninth features by measuring required time (sec) until the 
laminate surface starts to blister after being put in a solder bath of 
260.degree. C., it is found that the laminates including the 
resin-impregnated substrate of glass cloth according to EXAMPLES 81, 83 
and 85 denoted by mark "*" in TABLE 15 provide a further improved 
soldering heat resistance. It has been further found that the laminates of 
EXAMPLES 80 to 86 are also high in solvent resistance, as proved by 
dipping them in a boiling TCE solution for 5 minutes, resulting in no 
surface change at all and thus showing that their hardening is sufficient. 
According to the present invention, further modifications are possible. For 
example, other combinations of the materials for the PPO composition than 
those referred to in the foregoing EXAMPLES may be adopted. In an event, 
as will be readily appreciated, where such materials as PB, TAIC, TAC and 
the like which per se do not have the film-forming property are employed 
as the setting means, it is necessary to add means for providing to PPO 
the film-forming property, such as polystyrene, poly-paramethylstyrene or 
the like referred to. In the case, on the other hand, when such 
crosslinking polymer as STP which itself has both of the setting and 
film-forming properties, it is of course not required to add any other 
means for providing to PPO the film-forming property. 
Further, the PPO composition according to the present invention is suitable 
not only for making the laminates, but also in the form of a single film 
as further hardened to be in C-stage, in which instance the film may be 
provided on one surface with, for example, a printed-wiring so as to form 
a circuit film. 
It will be also appreciated that, in adhering the metallic foil to the 
films, the use of the PPO composition according to the present invention 
allows such adhesion to be reliably achieved without using any separate 
adhesive such as epoxy resin or the like, and that, in this respect, too, 
the invention achieves improvements in the heat-resistance and high 
frequency characteristics. 
Further, as PPO exhibits a low dielectric constant and less dielectric 
loss, another feature of the present invention lies in the preparation of 
a PPO resin composition that has a desired dielectric constant by mixing 
with the aforementioned PPO compositions an inorganic filler. Such a 
filler can be chosen such that the final PPO resin composition exhibits 
any desired dielectric constant. It is preferable to use an inorganic 
filler that has as large a dielectric constant as possible. Thus, the 
inorganic filler should preferably be of a relative dielectric constant of 
above 10. 
Suitable inorganic fillers include such ceramics as titanium dioxide 
ceramics, barium titanate ceramics, lead titanate ceramics, strontium 
titanate ceramics, calcium titanate ceramics, bismuth titanate ceramics, 
magnesium titanae ceramics, lead zirconate ceramics, and the like. These 
fillers can be used alone or in a mixture of two or more. This mixture can 
be sintered. Further, the ceramics can be refined or can be present as raw 
materials. If used as raw materials, the ceramics are preferably crushed 
after sintering. The inorganic fillers have different dielectric 
properties depending not only on their composition but also on their 
sintering and crushing conditions, i.e., particle size and particle size 
distribution. Their sintering condition varies according to the particular 
inorganic filler, but it is substantially the same as the calcining 
condition of ceramic dielectrics made from these fillers. While some of 
the calcined ceramic dielectrics are very hard and not easily crushed, it 
is necessary to crush the dielectric until a fixed particle size is 
obtained because, to a large extent, the particle size determines the 
dielectric properties. Further, since the particle size intimately relates 
to the ease of fabrication of uniform PPO resin compositions that include 
the inorganic filler, it is preferable that the inorganic filler be of 
finely divided particles of a size less that 50 .mu.m so that the 
production of the final product is not inconvenient. The particle size 
should preferably be in the range of 0.1 to 20.mu.m, or, most preferably, 
in the range of 0.5 to 7 .mu.m so as to avoid difficulties that may arise 
when the particle size is too small. 
While the inorganic filler may be used without any special surface 
treatment, it is possible to perform a surface treatment to improve, for 
example, the heat resistance and water absorption of the hardened 
composition. To this end, coupling agents such as silane, titanium, and 
the like are used. 
With the use of inorganic fillers that exhibit high dielectric constants, 
the resulting PPO resin compositions are relatively high in their 
dielectric constant in their hardened product state. It is also possible 
to adjust the dielectric constant of the hardened product of the PPO resin 
composition over a wide range by choosing the appropriate type and amount 
of the dielectric material used as the inorganic filler. That is, the 
inorganic filler acts as a dielectric constant adjuster and any type of 
filler high in dielectric constant may be used when it is only intended to 
elevate the dielectric constant. The upper limit of the amount of 
inorganic filler that can be used in the PPO resin composition is the 
point where undesirable loss of strength of the PPO resin composition 
occurs, such as where the hardened PPO resin composition product becomes 
porous. 
The composition ratio of the inorganic filler may be up to 450 parts by 
weight with respect to 100 parts by weight of the PPO resin composition 
except any solvent utilized, i.e., the resin composition including PPO, 
setting means, initiator, and any other organic material added as desired. 
In practice, the ratio should be below 400 parts, preferably below 200 
parts by weight of the PPO resin composition, as ratios over 450 parts by 
weight create undesirable strength deterioration. There is substantially 
no lower limit since the mere addition of an inorganic filler has a 
positive effect on the PPO resin composition. However, the addition of 
less than 5 parts by weight of inorganic filler to 100 parts by weight of 
the PPO resin composition causes no appreciable effect, while a 
practically appreciable effect arises when the inorganic filler is added 
in an amount of at least 30 parts by weight to 100 parts by weight of the 
PPO resin composition. 
The adjustment of the dielectric constant by the addition of an inorganic 
filler may be illustrated as follows. A PPO composition comprising 70 
par&:s by weight of PPO, 15 parts by weight of styrene-butadiene 
copolymer, 14 parts by weight of triallyl isocyanurate, and 1 part by 
weight of dicumyl peroxide exhibits a dielectric constant of 2.6 and a 
dielectric loss of 0.002 at 23.degree. C. and 1 MHz. When 255 parts by 
weight of barium titanate are added to 100 parts by weight of this PPO 
composition, the dielectric constant and dielectric loss of the PPO 
composition becomes 9.2 and 0.009 at 23.degree. C. and 1 MHz, 
respectively. Since the dielectric constant of barium titanate is 2000, 
the composition ratio of barium titanate added as the inorganic filler 
bears a close relationship to the dielectric properties of the PPO resin 
composition. Accordingly, the dielectric constant of the PPO resin 
composition can be set by fixing the composition ratio of the inorganic 
filler to the level that achieves the desired dielectric constant. 
To this end, the PPO composition and any other organic materials are 
dissolved in a suitable solvent so as to obtain a solution of 5 to 50 
weight %. An inorganic filler is added to the solution to adjust the 
dielectric constant of the resin composition solution. Of course, the 
inorganic filler is not dissolved but is dispersed in the solution. A 
substrate is impregnated with this PPO resin/inorganic filler composition 
by dipping the substrate into the solution so as to deposit the 
composition onto the substrate. The solvent may be removed from the 
produced prepreg by, e.g., drying or the composition may be semi-hardened 
so as to be in the B stage. The resin composition content of the prepreg 
is preferably from 30 to 80 weight %. 
The produced product, such as a laminate, of the PPO resin/inorganic filler 
composition retains the desirable properties of PPO and is excellent in 
its dielectric properties, heat resistance, chemical resistance, and 
dimensional stability. Furthermore, the dielectric constant of the 
composition can be set by the appropriate selection of the type and amount 
of the added inorganic filler, while the dielectric loss of the 
composition remains low. The following examples illustrate this aspect of 
the present invention. 
EXAMPLE 87 
In a 2 1. reactor having a vacuum means, 100 g of PPO, 30 g of 
styrene-butadiene copolymer, 40 g of triallyl isocyanurate, and 2 g of 
2,5-dimethyl-2,5-di-t-butyl-peroxyhexane-3 were mixed with 750 g of 
trichloroethylene sufficiently into a uniform solution. Thereafter, 150 g 
of powdery barium titanate (BaTiO.sub.3) of an average particle size of 1 
to 2 m was added and mixed with the solution in a ball mill for about 24 
hours, so as to be uniformly dispersed therein. Deaeration was then 
performed and the resultant PPO resin composition solution was applied 
onto a film of polyethylene terephthalate (PET) by means of a coating 
applicator so as to be 500 m thick. The coating was dried at 50.degree. C. 
for about 10 minutes. The produced film of the composition was separated 
from the PET film and was further dried at 170.degree.C. for 20 minutes to 
completely remove trichloroethylene and a sheet of the PPO resin 
composition having a thickness of about 150 m was obtained. Four of the 
sheets were stacked and joined under conditions of 220.degree. C. and 50 
kg/cm.sup.2 for 30 minutes, to have them completely set, and a laminate 
was thereby obtained. 
EXAMPLES 88-107 
EXAMPLES 88 to 107 as well as COMATIVE EXAMPLES 32 and 33 were carried 
out to obtain a variety of laminates. The process steps were substantially 
iden&:ical to those of EXAMPLE 87. The composition ratio of the solution 
as well as the solid state properties of the obtained laminates, including 
those of EXAMPLE 87, are as shown in TABLE 16, in which the composition 
ratio of the inorganic filler is shown in parts by weight with respect to 
100 parts of the PPO composition solution. 
TABLE 16 
__________________________________________________________________________ 
COMATIVE 
EXAMPLES EXAMPLES 
87 88 89 90 91 92 93 94 95 96 32 33 (*6) 
__________________________________________________________________________ 
Composition Ratio (wt. %) 
PPO 100 
100 100 100 
100 
100 
100 
100 100 
100 100 40 
Crosslink. 30 30 30 30 30 30 30 30 30 30 30 40 
polymer (*1) 
Crosslink. 40 40 40 40 40 40 40 40 40 40 40 120 
monomer (*2) 
Initiator (*3) 
2 2 2 2 2 2 2 2 2 2 2 6 
Inorg. A 87 
A 145 
A 200 
B 87 
A 47 
C 87 
A 58 
A 35 
H 58 
J 36 
-- -- 
filler (*4) B 58 D 17 
G 12 
E 6 
F 3 
Solid State Properties: 
Dielec. 9.2 
11.5 
12.8 
8.0 
8.6 
8.1 
14.6 
7.2 6.9 
15.0 
2.7 3.0 
const. (1 MHz) 
Dielec. 0.009 
0.010 
0.011 
0.009 
0.010 
0.010 
0.012 
0.011 
0.010 
0.015 
0.003 
0.003 
loss (1 MHz) 
Soldering heat 
120 
120 120 120 
120 
120 
120 
120 120 
90 30 90 
resist. (sec) 
Chemical OK OK OK OK OK OK OK OK OK OK OUT OK 
resist.(*s) 
Thermal exp. coeff. 
XY direct. (ppm/.degree.C.) 
45 40 40 50 45 45 45 50 50 50 100 20 
__________________________________________________________________________ 
97 98 99 100 101 102 103 104 105 106 107 
__________________________________________________________________________ 
Composition Ratio (wt. %): 
PPO 100 100 100 40 40 40 40 40 40 40 25 
Crosslink. 30 30 30 40 40 40 40 40 40 40 25 
polymer 
Crosslink. 40 40 40 120 120 120 120 120 120 120 50 
monomer 
Initiator 2 2 2 6 6 6 6 6 6 6 2 
Inorg. K 145 
L 116 
M 116 
A 63 
B 73 
C 73 
G 49 
K 121 
L 97 
M 97 
N 99 
filler 
Solid State Properties: 
Dielec 8.0 9.5 10.0 
8.5 9.0 9.1 
7.0 10.7 
9.5 10.2 
10.5 
const. (1 MHz) 
Dielec. 0.004 
0.005 
0.003 
0.004 
0.005 
0.004 
0.004 
0.004 
0.004 
0.005 
0.003 
Soldering heat 
120&lt; 
120&lt; 
120&lt; 
120&lt; 
120&lt; 
120&lt; 
120&lt; 
120&lt; 
120&lt; 
120&lt; 
120&lt; 
resist. (sec) 
Chemical OK OK OK OK OK OK OK OK OK OK OK 
resist. 
Thermal exp. coeff. 
15 15 15 17 16 16 19 15 15 15 15 
XY direct. (ppm/.degree.C.) 
__________________________________________________________________________ 
*.sup.1 styrenebutadiene copolymer 
*.sup.2 triallyl isocyanurate 
*.sup.3 2,5dimethyl-2,5-di-t-butyl-peroxybexane-3 
*.sup.4 A = BaTiO.sub.3 ; B = PbZrO.sub.3 ; C = PbTiO.sub.3 ; D = Sr 
TiO.sub.3 ; E = CaTiO.sub.3 ; F = MgTiO.sub.3 ; G = BaZrO.sub.3 ; H = 
K.sub.2 OPbO-SiO.sub.2 glass; J = Pb,Zr.sub.0.5 Ti.sub.0.5 O.sub.3 
*.sup.5 appearance change after 5 min. dipping in boiled TCE. 
*.sup.6 laminate including glass cloth. 
K = TiO.sub.2 ; L = Bi.sub.4 Ti.sub.3 O.sub.12 ; M = TiO.sub.2 
+BaTiO.sub.3 + ZrO.sub.2 calcined power; N = TiO.sub.2 + BaTiO.sub.3 + 
SrTiO.sub.3 calcined powder 
While the invention has been described in terms of various preferred 
embodiments, the skilled artisan will appreciate that various 
modifications, substitutions, omissions, and changes may be made without 
departing from the spirit thereof. Accordingly, it is intended that the 
scope of the present invention be limited solely by the scope of the 
following claims, including equivalents thereof.