Modified polyolefin resin and a composition containing the same

A modified polyolefin resin and a composition containing therein such modified polyolefin, having excellent adhesive property and heat-sealing property at the time of high speed forming operations, the modified polyolefin resin consisting essentially of: a copolymer of ethylene and .alpha.-olefin having 4 or more carbon atoms, the copolymer having a density in a range of from 0.890 to 0.910 g/cm.sup.3, a ratio of a weight-average molecular weight (Mw) to a number-average molecular weight (Mn) of Mw/Mn=2 to 15, and a product of a melt tension (g) and a melt-index (g/10 min.) of a molten resin measured at 160.degree. C. of 4 or below; and unsaturated carboxylic acid or derivatives thereof grafted on the ethylene type copolymer at a ratio of from 0.01 to 3% by weight.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a modified polyolefin resin and a composition 
containing the same. 
Polyolefins modified with polymerizable monomers having in their molecules 
a polar group such as unsaturated carboxylic acid and its derivatives have 
been widely used for imparting adhesive property, dying property, and 
miscibility with other resins to those polyolefins which are primarily 
non-polar, hence no adhesive property and compatibility with other polar 
substances, and for producing a composite material by blending such 
polyolefins and other substances. For instance, such modified polyolefins 
are used for the manufacture of a multi-layered film and sheet in the form 
of a laminated product with metals or polar resins (such as polyamide, 
polyester, copolymer of ethylene and vinyl alcohol, polyvinyl halide, and 
so forth). Besides this, the modified polyolefins are also used for 
adhesion between a coated protective layer and a metal constituting a 
metal shaped article. Further, such polyolefin per se or a composition 
containing the same in it is used for obtaining a composition having good 
dispersibility and excellent mechanical strength, with increased 
compatibility and adhesivity between filler, pigment, etc. and the matrix 
resin. In certain other cases, the modified polyolefin per se is present 
in the matrix resin in a state of its being in a favorable dispersion to 
thereby improve impact resistance and other properties of the matrix 
resin. 
The present invention is directed to the modified polyolefin resin capable 
of being widely used in such use, and, in particular, to a resin 
composition effective for manufacture of a composite film or sheet. 
2. Description of Prior Arts 
The technique of modifying an ethylene type copolymer containing ethylene 
as the principal constituent (hereinafter abbreviated as "polyethylene") 
with a polar monomer has been well known. Above all, polyethylene which 
has been modified with unsaturated carboxylic acid or its anhydride 
possesses good adhesion with metal, epoxy resin, and so forth, hence it is 
used for a metal pipe coating, etc., and moreover such modified 
polyethylene is capable of producing a composite of a high barrier resin 
by joining a composite film or sheet composed of the ethylene type resin 
with nylon, ethylene and vinyl alcohol copolymer, polycarbonate resin, 
polyethylene terephthalate, aluminum foil, etc., on account of which it 
has been widely used as the food packing material. 
There are several kinds of polyethylene used for modified polyethylene such 
as high pressure method, low density polyethylene (.rho.=0.915 to 0.930 
g/cm.sup.3), medium or low pressure method, high density polyethylene 
(.rho.&gt;0.94 g/cm.sup.3), medium or low pressure method, medium density 
polyethylene (.rho.=0.93 to 0.95 g/cm.sup.3), and so forth. A linear 
copolymer of much lower density is disclosed in, for example, Japanese 
Unexamined Patent Publication No. 165413/1982, which is directed to a 
metal laminate body using a linear, low density polyethylene having a 
density of 0.915 to 0.935 g/cm.sup.3 (which will hereinafter be 
abbreviated as "LLDPE"). 
According to that invention, use of LLDPE would contribute to improve the 
adhesive strength and the stress-cracking resistance of the resin 
composition. However, while the resin composition to be obtained with use 
of LLDPE might be superior in its adhesive strength and the 
stress-cracking resistant property to the resin composition with the 
conventional medium or low pressure method, high density polyethylene and 
high pressure method, low density polyethylene as the base material, it 
must be said that such resin composition still falls short of its adhesive 
strength and heat-sealing property at the time of high speed molding of 
the resin composition, which is the principal performance to be the gist 
of the present invention. 
Further, Japanese Unexamined Patent Publication No. 170940/1982 discloses a 
modified polyethylene using a medium or low pressure method ethylene 
copolymer having a density of from 0.900 to 0.940 g/cm.sup.3. In the 
examples of this Japanese Unexamined Patent Publication, however, there is 
only description of an example of the modified polyethylene having a 
density in a range of from 0.920 to 0.925 g/cm.sup.3, and nothing is said 
about the effect to be derived from the characteristics of the 
polyethylene according to the present invention with the exception of the 
description such that, when used for coating of metal material, such 
modified polyethylene provides excellent durability in adhesion (such as 
resistance to warm water, resistance to stress-cracking, and so forth). 
Furthermore, as a copolymer having a much lower density, there has been 
known a modified resin obtained by modification of a copolymer of ethylene 
and .alpha.-olefin with a low degree of crystallization in a range of from 
30% to a few percent (.rho.=0.86 to 0.88 g/cm.sup.3) and a copolymer 
rubber of ethylene and .alpha.-olefin (.rho.=0.86 to 0.87 g/cm.sup.3) of 
much lower density. For example, Japanese Unexamined Patent Publication 
No. 82/1979 discloses a blend of a modified polymer obtained by grafting 
maleic anhydride on a copolymer of ethylene and .alpha.-olefin having a 
degree of crystallization of 30% or below and a crystalline polyolefin 
resin. However, examples in this Unexamined Japanese Patent Publication 
disclose only a copolymer having a density of not reaching 0.89 g/cm.sup.3 
(which is expressed in terms of a comonomer composition), but not a single 
description can be seen in it as to the effect to be derived from 
definition of the physical properties that can be expressed by a value of 
a product of melt tension and melt-index of the polymer material. Besides 
this, there have been proposed various techniques of blending an 
unmodified rubbery copolymer and a modified substance of a crystalline 
polyolefin, and so on, although no use has ever been made of a polymer 
having the density and the characteristics as that of the present 
invention. 
Possibility of obtaining a copolymer having a density of from 0.890 to 
0.910 g/cm.sup.3 by copolymerization of ethylene and .alpha.-olefin has 
been known per se. This technique, however, has not been put into practice 
upto recent years, because of various difficulties to be overcome for the 
purpose of its production in an industrialized scale, such as manner of 
handling the polymer (in particular, agglutination of polymer particles), 
increase in components soluble in solvent, and others. In recent years, 
such industrialized production has become feasible owing to improvement in 
the slurry polymerization method or improvement in the gas-phase 
polymerization method. 
SUMMARY OF THE INVENTION 
The present inventors have conducted studies and researches as to 
applicable extent of such low density polyethylene, as the result of which 
they have found out that, of those polyethylenes of such low density 
range, use of a low density polyethylene having a particular range of 
physical properties would contribute to improve various properties 
required of the modified polyethylene having excellent adhesive property. 
On the basis of this finding, they have arrived at the present invention. 
It is therefore an object of the present invention to provide a modified 
polyolefin resin and a composition containing therein such modified 
polyolefin having excellent adhesive property and heat-sealing property at 
the time of high speed molding. 
It is another object of the present invention to provide a composite body 
of the modified polyolefin having a high rate of adhesive sustaining ratio 
at a relatively high temperature. 
According to the present invention, in one aspect thereof, there is 
provided a modified polyolefin resin, which consists essentially of: a 
copolymer of ethylene and .alpha.-olefin having 4 or more carbon atoms, 
said copolymer having a density in a range of from 0.890 to 0.910 
g/cm.sup.3, a ratio of a weight-average molecular weight (Mw) to a 
number-average molecular weight (Mn) of Mw/Mn=2 to 15, and a product of a 
melt tension (g) and a melt-index (g/10 min.) of a molten resin measured 
at 160.degree. C. of 4 or below; and unsaturated carboxylic acid or 
derivatives thereof grafted on said ethylene type copolymer at a ratio of 
from 0.01 to 3% by weight. 
According to the present invention, in another aspect of it, there is 
provided a modified polyolefin resin composition, which consists 
essentially of: (1) a modified polyolefin resin composed of a copolymer of 
ethylene and .alpha.-olefin having 4 or more carbon atoms, said copolymer 
having a density in a range of from 0.890 to 0.910 g/cm.sup.3, a ratio of 
a weight-average molecular weight (Mw) to a number-average molecular 
weight (Mn) of Mw/Mn=2 to 15, and a product of a melt tension (g) and a 
melt-index (g/10 min.) of a molten resin measured at 160.degree. C. of 4 
or below, and unsaturated carboxylic acid or derivatives thereof grafted 
on said ethylene type copolymer at a ratio of from 0.01 to 3% by weight; 
and (2) unmodified polyolefin type resin blended with said modified 
polyolefin resin at a ratio of from 1:99 to 99:1 (by weight) with a 
content of said unsaturated carboxylic acid or derivatives thereof present 
in said blended composition ranging from 0.01 to 1% by weight. 
The foregoing objects, other objects as well as specific ingredients to 
obtain the modified copolymer, and method and conditions for such 
modification according to the present invention will become more apparent 
and understandable from the follow-detailed description thereof when read 
in connection with several preferred examples thereof. 
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
By the use of the modified polyolefin resin composition according to the 
present invention, there can be obtained a polymer blend capable of 
exhibiting its adhesive strength even under stringent shaping conditions 
and having a high adhesive sustaining ratio at a relatively high 
temperature. 
For the production of the low density polyethylene satisfying such 
requirements, there may be adopted a method as disclosed in Japanese 
Unexamined Patent Publications Nos. 68306/1984, 230011/1984, and others. 
When ethylene and .alpha.-olefin are subjected to the copolymerization 
under the conditions as described in these Japanese Unexamined Patent 
Publications, using the catalysts as described therein, there can be 
obtained a copolymer having a density of from 0.890 to 0.910 g/cm.sup.3 . 
It should however be noted that the present invention is not necessarily 
restricted to the polymerization method and polymerization catalysts as 
disclosed in these Japanese Unexamined Patent Publications, but any other 
methods may be possibly adopted, provided that the copolymerization is 
effected with use of the Ziegler catalyst. 
The copolymer to be obtained is a copolymer of ethylene and .alpha.-olefin 
(.rho.=0.890 to 0.910 g/cm.sup.3). However, since the copolymer produced 
by using propylene as the .alpha.-olefin is somewhat inferior in its 
mechanical strength, etc. for the purpose of its use as the base resin for 
the modified resin, it is preferable to use a copolymer of the 
.alpha.-olefin having 4 or more carbon atoms, or more particularly, the 
.alpha.-olefin having from 4 to 8 carbon atoms, from the aspect of the 
physical properties of the copolymer, though a quantity of propylene may 
be included for the copolymerization. The molecular weight distribution of 
the copolymer may be indicated in terms of distribution by flow ratio (FR) 
of the molten polymer and gel-permeation chromatography (GPC). Those 
copolymers having relatively narrow distribution of Mw/Mn in a range of 
from 2 to 15 (or more preferably below 10) and an FR value of 30 or below 
indicate favorable result. When a ratio of Mw/Mn exceeds 15, the shaping 
property of the copolymer resin becomes superior, but its required 
adhesive strength lowers. From the standpoint of melt tension as an index 
for the degree of branching, those copolymers having a low melt tension 
per melt-index, and a product of the melt tension (g) and the melt-index 
(g/10 min.) of 4 or below, or more preferably 2.5 or below, are desirable. 
When this value exceeds 4, the shaping property of the copolymer resin 
becomes satisfactory, while its adhesive strength as required becomes 
lowered. With the high pressure method polyethylene as the branching type 
polymer, its melt tension after the grafting reaction increases, even if 
it has a low density, thus inviting unfavorable result. 
As the monomer for the modification, use may be made of unsaturated 
carboxylic acid or its derivatives. Examples of the unsaturated carboxylic 
acid are: acrylic acid, methacrylic acid, maleic acid, fumaric acid, 
itaconic acid citraconic acid, and so forth. Suitable derivatives of the 
unsaturated carboxilic acids include acid anhydrides, esters, amides, 
imides, metal salts, and so on, examples of which are: maleic anhydride, 
citraconic anhydride, itaconic anhydride, methyl acrylate, methyl 
methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl 
methacrylate, glycidyl acrylate, glycidyl methacrylate, hydroxyethyl 
acrylate, hydroxybutyl acrylate, maleic acid monoethyl ester, maleic acid 
diethyl ester, fumaric acid monomethyl ester, fumaric acid dimethyl ester, 
itaconic acid monomethyl ester, itaconic acid diethyl ester, acryl amide, 
methacryl-amide, maleic acid monoamide, maleic acid diamide, maleic 
acid-N-monoethyl amide, maleic acid-N,N-diethyl amide, maleic 
acid-N-monobutyl amide, maleic acid-N,N-dibutyl amide, fumaric acid 
monoamide, fumaric acid diamide, fumaric acid-N-monoethylamide, fumaric 
acid-N,N-diethylamide, fumaric acid-N-monobutylamide, fumaric 
acid-N,N-dibutylamide, maleimide, N-butyl maleimide, N-phenyl maleimide, 
sodium acrylate, sodium methacrylate, potassium acrylate, potassium 
methacrylate, and others. Furthermore, as the alicyclic unsaturated 
carboxylic acids, the following are appropriate examples thereof: 
cis-4-cyclohexene-1,2-dicarboxylic anhydride (commonly called 
tetrahydrophthalic anhydride), cis-4-cyclohexene-1,2-dicarboxylic acid 
(commonly called tetrahydro-phthalic acid), 
endo-bicyclo[2,2,1]-5-heptene-2,3-dicarboxylic anhydride (commonly called 
high mix acid anhydride), endo-bicyclo[2,2,1]-5-heptene2,3-dicarboxylic 
acid (commonly called high mix acid), 
endo-bicyclo[2,2,1]-1,2,3,4,7,7-hexachloro-2-heptene-5,6-dicarboxylic 
anhydride (commonly called chlordanic anhydride), 
endo-bicyclo[2,2,1]-1,2,3,4,7,7-hexachloro-2-heptene-5,6-dicarboxylic acid 
(commonly called chlordanic acid), and others. 
As the other polar monomer, there may be used vinyl chloride, vinyl 
acetate, vinyl formamides (e.g., N-vinyl formamide), vinyl ethers, vinyl 
silanes (e.g., triethoxy vinyl silane), and others. 
Moreover, at the graft-modification of these polar monomers, there may also 
be effected mixed use of the above-listed monomers or graft 
copolymerization of the non-polar monomers (e.g., styrene, etc. as 
disclosed in Japanese Unexamined Patent Publication No. 34659/1972) with a 
view to improving the graft efficiency, the adhesive property, and so 
forth. 
To an extent that does not impair the characteristics of the present 
invention, there may also be feasible to carry out improvement by blend of 
second and third polymers. Examples of such improvement are: blending of a 
rubber component, blending of low crystalline polyethylenes having much 
lower density, blending of ethylene-vinyl acetate copolymer, 
ethylene-ethyl acrylate copolymer, and so forth. For the purpose of this 
blending, the techniques as disclosed in Japanese Unexamined Patent 
Publications Nos. 98784/1976, 80334/1977, etc. may be used. 
For the grafting reaction, there may usually be adopted any known methods. 
That is to say, it is only sufficient that the polyolefin, the unsaturated 
carboxylic acid or its monomeric derivatives, and a radical generator be 
brought into mutual contact under such conditions that the radical 
generator may effectively act on these components. For this grafting 
reaction, there may be used any of various methods such as the 
melt-kneading method using an extruder, etc.; the solution method, by 
which the polymer is dissolved into a solvent; the slurry method, in which 
the polymer particles are suspended in a medium; and the gas phase method. 
With a view to improving the adhesive capability, it is also possible to 
treat the copolymer with an epoxy resin or a poly-functional compound, 
etc. containing therein the amino group, the hydroxyl group, and so forth 
during or after the grafting reaction, or to adopt a method of removing 
the unreacted monomers and the by-produced volatile components by the 
operations of simple heating, washing, or else. 
The quantity of the monomer to be modified by the grafting may preferably 
be in a range of from 0.01 to 10% by weight in terms of the weight of the 
base resin, on which the grafting is to be done. More preferred range may 
be from 0.01 to 3% by weight. Further, in a blend of the modified 
polyolefin resin and the unmodified polyolefin resin, it is desirable that 
the monomer may be so mixed as to bring its quantity in a range of from 
0.01 to 5% by weight, or more preferably from 0.01 to 1% by weight, in 
terms of the quantity of the modified monomer in the total composition. 
Outside the above-mentioned range, when the quantity of the modified 
monomer is small, the adhesive strength as intended by the present 
invention is not sufficient; and when its quantity is large, not only 
gelation, coloring, deterioration in the polymer, and so forth tend to 
readily occur at the time of the grafting reaction, but also improvement 
in the adhesive property can no longer be recognized. 
In the present invention, the modified polyolefin resin as obtained in the 
above-described manner is useful per se, and can be employed for various 
purposes, but it can also be used in the form of a composition blended 
with unmodified polyolefin resin. 
As the unmodified polyolefin resin to be blended with the graft-modified 
polyolefin resin, there may be used any of those resins which are known 
generally as polyolefin. Examples of such unmodified polyolefin resins 
are: homopolymer of ethylene, copolymers of ethylene and other 
.alpha.-olefins, homopolymer of propylene, copolymers of propylene and 
other olefins, homopolymer of .alpha.-olefins having more number of 
carbon, copolymers of such .alpha.-olefin of high carbon content and other 
.alpha.-olefins, random copolymers of these olefins as the principal 
constituent and partially polymerizable other polar monomers, block 
copolymers, and graft copolymers. More concretely, there may be 
exemplified the following: high density polyethylene medium or low 
pressure method, linear low density polyethylene, high pressure method, 
low density polyethylene, copolymer of low crystalline ethylene and 
.alpha.-olefin, copolymer rubber of ethylene and .alpha.-olefin, copolymer 
rubber of ethylene, .alpha.-olefin and diene, polypropylene, copolymer of 
propylene and .alpha.-olefin, polybutene-1, poly-4-methyl-pentene-1, 
poly-3-methylbutene-1, copolymer of ethylene and vinyl ester (e.g., 
copolymer of ethylene and vinyl acetate), copolymer of ethylene and 
acrylic acid ester (e.g., copolymer of ethylene and ethyl acrylate), 
copolymer of ethylene and unsaturated carboxylic acid (e.g., copolymer of 
ethylene and acrylic acid), polyethylene modified with unsaturated 
carboxylic acid, polypropylene modified with unsaturated carboxylic acid, 
and so forth. 
The blending of the modified polyethylene having the particular physical 
properties according to the present invention and these polyolefins can be 
usually done by an extruder, a kneader, Banbury mixer, and other mixing 
and kneading machines. The blending ratio may be in a range of from 1:99 
to 99:1 (by weight), or preferably from 5:95 to 95:5 (by weight), or more 
preferably from 20:80 to 80:20 (by weight), or so. From the standpoint of 
economy, however, a range of from 10:90 to 60:40 (by weight) is highly 
preferable. 
It is also possible to add to the adhesive composition to be used in the 
present invention various additives such as stabilizers, pigments, 
fillers, and so on, which are usually used in the polyolefin resins, 
within such an extent that does not impair its effect of adhesiveness. It 
is further possible to add thereto various reforming materials such as 
copolymer rubber of ethylene and .alpha.-olefin, and others. 
The modified polyolefin obtained by graft-modification of such polyolefin, 
or the adhesive composition prepared by use of such modified polyolefin 
possesses characteristics such that not only it exhibits high degree of 
adhesiveness at a normal temperature by being combined with polar resins, 
metals, and so on, but also it loses its adhesive capability to a less 
extent even at a relatively high temperature, hence it is superior to 
those conventional compositions in respect of its exhibiting a 
well-balanced performance. 
Furthermore, the resin composition according to the present invention 
possesses appropriate melting point and pliability, in addition to which 
it has good seal-forming property as a heat-sealing layer for a composite 
film, hence it exhibits excellent capability in its sealing strength as 
well as heat-resistant sustaining property of the sealing strength in 
comparison with those of ethylene/vinyl acetate copolymer which has 
conventionally been used. 
The polar resin layer to be used for this purpose may be exemplified as 
follows: ethylene/vinyl alcohol copolymer, polyamide resin, polyester 
resin, polyvinyl halide, and so forth. 
The ethylene/vinyl alcohol copolymer is one obtained by partially or 
substantially totally saponifying the acetic acid group in the 
ethylene-vinyl acetate copolymer to turn it into the hydroxyl group. There 
is no restriction to its chemical composition. For example the 
ethylene/vinyl alcohol copolymer having an average molecular weight of 
from 10,000 to 100,000 and the ethylene content of from 10 to 70 mol % is 
usually used. In consideration, however, of the gas-barrier property, the 
film forming property, and so forth of the copolymer, it is preferable to 
use the ethylene/vinyl alcohol copolymer obtained by saponifying the 
ethylene/vinyl acetate copolymer with the ethylene content of from 50 to 
30 mol % in a manner to bring its degree of saponification to 90% or 
higher. 
As the polyamide resin, there may be used those linear high polymers having 
the amide bond and to be obtained by opening the ring of lactam, 
condensation of diamine and dicarboxylic acid, and so on; for example such 
linear high polymers having an average molecular weight of from 15,000 to 
60,000 and [.eta.]=1.0 to 6.0, or so are used. Examples of such linear 
high polymers that can be used are: Nylon 6, Nylon 6.6, Nylon 6.10, Nylon 
11, Nylon 6.11, Nylon 6T, and so forth. Further, there may also be used 
polyester amide, polyether amide, polyamide-imide, etc. containing in its 
molecules those bonds other than amide. 
The polyester resin refers to a thermoplastic polyester resin which is 
principally composed of dibasic acid and diol. Representative examples of 
such polyester resins are: polyethylene terephthalate, polybutylene 
terephthalate, polyethylene isophthalate, polyethlener 2,6-naphthalene 
dicarboxylate, polyphenylene terephthalate, copolycondensate of bisphenol 
A and terephthalic acid, and other aromatic polyesters. These polyester 
resins may also be modified products which are partially softened with 
diol such as polyethylene oxide, glycol, etc. or plural copolycondensates 
such as polyester amide, polyester/ether amide, in which the polyamide 
component is partially mixed to be integrated. 
Examples of the polyvinyl halides are: polyvinyl chloride, polyvinylidene 
chloride, and so forth. 
As the metal for producing complex bodies by use of the adhesive resin 
according to the present invention, there may be exemplified aluminum, 
iron, stainless steel, and other ferrous alloys; copper, nickel, and so 
on. Of these metals, aluminum and iron are preferably used. These metal 
materials, at the time of producing a composite body, can be used in 
various forms such as foil, sheet, plate, tube, and various other 
configurations. Such metal materials may be subjected in advance to the 
surface treatment such as chromic acid treatment, titanium compound 
treatment, and others, which are effective for adhesion and 
corrosion-prevention. Use of those resins such as epoxy resin as the 
primer, depending on necessity, is the technique that can be applied to 
the manufacture of a laminated body which is the object of the present 
invention. 
With a view to enabling those persons skilled in the art to put the present 
invention into practice, and to prove superiority of the present invention 
over the conventional product, the following preferred examples of the 
present invention and comparative examples of the conventional product are 
presented. It should be noted, however, that the present invention is not 
limited to these preferred examples alone, but any changes and 
modifications may be made in the ingredients used and the reaction 
conditions adopted, without departing from the spirit and scope of the 
invention as recited in the appended claims. 
(Method for Measuring the Physical Properties) 
(1) Melt-index (MI) and Flow Ratio (FR): 
The melt-index (MI) was measured on the basis of a load of 2.16 kg in 
accordance with ASTM-D1238. Polyethylene type resin was measured at 
190.degree. C., and polypropylene type resin was measured at 230.degree. 
C. 
The flow ratio (FR) was measured in the same manner as mentioned above for 
the flow rate (g/10 min.) of the resin at the respective shearing stress 
of 10.sup.6 dyn/cm.sup.2 and 10.sup.5 dyn/cm.sup.2, from which a ratio of 
Q.sub.10 6/Q.sub.10 5 was found. The magnitude of the FR value is 
considered to correspond to the molecular weight distribution. 
(2) Molecular Weight Distribution: 
The molecular weight distribution was measured by the gel permeation 
chromatography (GPC). The device used for the measurement was Model 
"HLC-811" manufactured by Toyo Soda Manufacturing Co., Ltd., Japan, and 
two units of the chromatographic column (TSK-gel and GMH-6), each having 
60 cm in length. The measurement was carried out at 140.degree. C. using 
orthodichlorobenzene as the solvent. The molecular weight was expressed in 
terms of the polyethylene conversion. 
(3) Thermal Analysis: 
The measurement was done by the differential scanning calorimetry (DSC) 
method. The device used for the measurement was Model "Parkin-Elmar I". 
(4) Melt Tension (MT): 
An orifice having a diameter of 2 mm, a length of 8 mm, and an in-flow 
angle of 180.degree. was mounted on a melt tension meter manufactured by 
Toyo Seiki K.K., Japan. The measurement was done at a temperature of 
160.degree. C., a quantity of extrusion of 0.25 g/min., and a take-up 
speed of 152 cm/min. Melt tension is expressed in g. 
I. Manufacture of Polymer 
The polymers as shown in Table 1 below were used. 
TABLE 1 
__________________________________________________________________________ 
MI Melting 
Heat of 
(g/10 MT Density point 
fusion 
min.) (g) MI .times. MT 
(g/cm.sup.3) 
Mw/Mn 
FR (.degree.C.) 
(Kcal/g) 
__________________________________________________________________________ 
.circle.A *.sup.1 
1.5 1.2 1.8 0.900 
7.0 24 90 18 
.circle.B *.sup.2 
0.82 
2.6 2.1 0.907 
7.9 20 117 13.8 
.circle.C *.sup.3 
0.40 
8.0 3.2 0.904 
24.5 55 119 12.6 
.circle.D *.sup.4 
3.9 0.6 2.4 0.88 8.7 12 60 18 
.circle.E *.sup.5 
1.8 -- -- 0.86 3.0 18 -- -- 
.circle.F *.sup.6 
2.0 12 24 0.918 
18.9 30 -- -- 
.circle.G *.sup.7 
1.8 0.92 
1.7 0.921 
3.3 20 119 -- 
.circle.H *.sup.8 
0.7 6.2 4.3 0.925 
10.2 65 116 -- 
.circle.I *.sup.9 
11 &lt;0.5 
&lt;5.5 0.964 
-- 22 134 -- 
.circle.J *.sup.10 
0.7 -- -- 0.90 -- -- 150 -- 
__________________________________________________________________________ 
(NOTE) 
*.sup.1 Copolymer of ethylene and butene1 as disclosed in Example 3 of 
Japanese Unexamined Patent Publication No. 68306/1984 
*.sup.2 DFDA 1137 NT (polyethylene) produced by Union Carbide Corporation 
U.S.A. 
*.sup.3 DFDA 1138 NT (polyethylene) produced by Union Carbide Corporation 
U.S.A. 
*.sup.4 Copolymer of ethylene and butene1 as disclosed in Japanese 
Unexamined Patent Publication No. 82/1979 
*.sup.5 JSR EPO2P (ethylene/propylene rubber) produced by Nippon Syntheti 
Rubber Co. Ltd. 
*.sup.6 NOVATECH F250 (high pressure method, low density polyethylene) 
produced by Mitsubishi Chemical Industries Ltd. 
*.sup.7 GP-2 (ethylene/butene1 copolymer) produced by Union Carbide 
Corporation, U.S.A. 
*.sup.8 GP-1 (ethylene/butene1 copolymer) produced by Union Carbide 
Corporation, U.S.A. 
*.sup.9 Medium or low pressure, high density polyethylene 
*.sup.10 Propylene/ethylene copolymer 
II. Manufacture of Modified Polyolefin 
0.5 part by weight of maleic anhydride and 0.025 part by weight of 
.alpha.,.alpha.-di-t-butyl peroxyparaisopropylbenzene were mixed with 100 
parts by weight of each of the polymers .circle.A , .circle.B , 
.circle.C , .circle.D , .circle.E , .circle.F , and .circle.G as 
listed in Table 1 above. Then, the mixture was melted and kneaded at 
230.degree. C. by use of a single shaft extruder having an inner diameter 
of 30 mm and a length-to-diameter ratio of L/D=24 to thereby carry out the 
grafting reaction. The graft-modified polymer was sufficiently extracted 
with acetone to remove the unreacted monomers, after which the quantity of 
maleic anhydride as grafted was found by means of the infrared 
spectroscopy. The results are as shown in Table 2 below. 
III. Manufacture of Resin Blend 
Each of the above-mentioned graft-modified polymers was blended with 
various polyolefins. The blending operation was done by use of a single 
shaft extruder having an inner diameter of 40 mm. The polyethylene type 
resin was melted and kneaded at 210.degree. C., while the propylene type 
resin was melted and kneaded at 230.degree. C. The results are as shown in 
Table 2 below. 
IV. Measurement of Adhesive Strength 
The above-mentioned resin compositions and the saponified resin of 
ethylene/vinyl acetate copolymer ("SOANOL-E": a registered trademark for 
the resin product of Nippon Synthetic Rubber Co., Ltd.) was co-extruded 
through a die to thereby from a composite inflation film composed of a 
blended composition layer of modified ethylene copolymer (inner layer) and 
a saponified resin layer of ethylene/vinyl acetate copolymer (outer 
layer). 
The co-extrusion was done through a die having an inner diameter of 80 mm 
at a die temperature of 210.degree. C., an extruder at the side of the 
blended composition of modified ethylene copolymer having a diameter of 40 
mm, L/D=24, and at a temperature of 210.degree. C., and an extruder at the 
side of the saponified resin of ethylene-vinyl acetate copolymer having a 
diameter of 30 mm, L/D=20, and at a temperature of 210.degree. C. The 
take-up speed of the composite inflation film was 6.5 m/min., its below-up 
ratio was 1.2, thickness of the saponified resin film of ethylene/vinyl 
acetate copolymer was 50 microns, and thickness of the blended composition 
of the modified ethylene copolymer was 50 microns. 
In the next place, while maintaining the conditions for the extrusion by 
the extruder as they were, the film take-up speed and the cooling air 
quantity were controlled to thereby produce a composite film, each of the 
constituent resin layers having thickness of 25 microns. Measurement of 
this composite film for its T-shaped peeling strength was based on JIS 
K6854. The results of the measurements are as shown in Table 2 below.

EXAMPLES 1 to 5 
Polyethylene .circle.A was modified, with which various polyolefins were 
blended to prepare different polymer blends. Using these polymer blends 
and saponified resin of ethylene/vinyl acetate copolymer (EV-OH resin), a 
composite film was formed. These various composite films exhibited their 
favorable adhesive strength, though, depending on the resin to be blended, 
there was a difference in the value of such adhesive strength. The results 
are as shown in Table 2 below. 
EXAMPLES 6 to 8 
The same experiment as mentioned in the preceding Examples was conducted 
with use of polyethylene .circle.B . The results are as shown in Table 2 
below. 
COMATIVE EXAMPLE 1 
The same experiment as in Example 1 above was conducted by use of polymer 
.circle.C with wide distribution of the molecular weight, though its 
density, etc. were within the predetermined range. The adhesive strength 
of the modified resin was lower than that of Example 1. The results are as 
shown in Table 2 below. 
COMATIVE EXAMPLE 2 
Polymer .circle.D having its density slightly lower than the 
predetermined range was used. The resulted modified polymer exhibited its 
favorable adhesive strength at a normal temperature, but its adhesive 
sustaining ratio at 60.degree. C. was lower than that of Example 3. The 
results are as shown in Table 2 below. 
COMATIVE EXAMPLES 3 to 5 
High pressure method, low density polyethylene was used. This polymer have 
a large melt tension characteristic due to its branching. The resulted 
modified resin exhibited its adhesive strength inferior to that the 
modified resin in Example 1 above, and its adhesive sustaining ratio was 
also low. The same results were obtained even in the case of blending high 
pressure method, low density polyethylene and propylene/ethylene 
copolymer, as shown in Table 2 below. 
COMATIVE EXAMPLE 6 
Modified resin of ethylene/propylene rubber was used. The resin showed its 
favorable adhesive strength at a normal temperature, but its adhesive 
sustaining ratio was also poor. The results are as shown in Table 2 below. 
COMATIVE EXAMPLE 7 
Using linear, low density polyethylene .circle.G the same experiment as 
in Example 1 above was conducted. The resulted resin was poor in its 
adhesive strength in comparison with the resin of Example 1 above. The 
results are as shown in Table 2 below. 
COMATIVE EXAMPLE 8 
Using linear, low density polyethlene .circle.H , the same experiment as 
in Example 1 above was conducted. The resulted resin was poor in its 
adhesive strength in comparison with the resin of Example 1 above, and its 
adhesive sustaining ratio was also poor. The results are as shown in Table 
2 below. 
TABLE 2 
__________________________________________________________________________ 
Quantity of 
Quantities of 
maleic modified 
Adhesive strength 
Adhesive 
Polyolefin 
anhydride polyolefin in 
with EV-OH resin 
sustaining 
used for 
grafted 
Blending 
polymer blend 
(g/15 mm) [23.degree. C.] 
60.degree. C. 
ratio at 23.degree. C. 
modification 
(%) resin 
(wt. %) 25.mu./25.mu. 
50.mu./50.mu. 
50.mu./50.mu. 
(%) 
__________________________________________________________________________ 
Example 1 
.circle.A 
0.48 -- 100 320 780 550 0.71 
Example 2 
" " .circle.I 
30 65 980 710 0.72 
Example 3 
" " .circle.F 
30 350 800 560 0.70 
Example 4 
" " .circle.G 
30 400 900 660 0.73 
Example 5 
" " .circle.J 
30 120 350 260 0.73 
Example 6 
.circle.B 
0.17 -- 100 300 450 -- -- 
Example 7 
" " .circle.F 
30 70 650 -- -- 
Example 8 
" " .circle.G 
30 55 350 -- -- 
Comparative 
.circle.C 
0.20 -- 100 30 120 -- -- 
Example 1 
Comparative 
.circle.D 
0.45 .circle.F 
30 310 720 470 0.65 
Example 2 
Comparative 
.circle.F 
0.40 -- 100 30 50 30 0.60 
Example 3 
Comparative 
" " .circle.F 
30 45 65 45 0.70 
Example 4 
Comparative 
" " .circle.J 
30 30 45 35 0.80 
Example 5 
Comparative 
.circle.E 
0.36 .circle.F 
30 300 650 420 0.65 
Example 6 
Comparative 
.circle.G 
0.37 -- 100 60 145 100 0.70 
Example 7 
Comparative 
.circle.H 
0.36 -- 100 35 110 65 0.55 
Example 8 
__________________________________________________________________________ 
As described in the foregoing, when the modified polyolefin resin and the 
composition containing the same are used, there can be obtained a 
composite body which is excellent in its adhesive property as well as its 
heat-sealing property at a high speed forming, and which has high adhesive 
sustaining ratio at a relatively high temperature condition, hence the 
resin according to the present invention is industrially useful.