CA1150882A

CA1150882A - Adhesive blends and composite structures

Info

Publication number: CA1150882A
Application number: CA000375896A
Authority: CA
Inventors: Seymour Schmukler; John Machonis, Jr.; Mitsuzo Shida
Original assignee: Chemplex Co
Current assignee: Equistar Chemicals LP
Priority date: 1980-08-15
Filing date: 1981-04-22
Publication date: 1983-07-26
Also published as: DE3140987A1; FR2488614A1; GB2081723A; GB2081723B; FR2488614B1; NL8103772A; NL185155B; DE3126145A1; JPS5753578A; DE3140987C2; JPS628461B2; DE3126145C2

Abstract

Abstract Compositions of matter having properties that make them strong adhesives to various substrates and especially for adhering polypropylene to various polar substrates. These compositions comprise blends of a graft copolymer of a polyethylene backbone grafted with at least one grafting monomer comprising one or more of polymerizable ethylenically unsaturated carboxylic acids or the anhydrides of such acids blended with a blending resin that is a mixture of one or more linear low density polyethylenes and one or more polypropyl-enes. The disclosure also includes composite structures comprising one or more substrates and a blend of the above as the adhesive in contact with the substrate or substrates.

Description

liSi~38;~

ADHESIVE BLENDS AND COMPOSITE STRUCTURES

Composite structures of polypropylene (PPI
and polar substrates are finding great utility in industry at the present time. One solution to the problem of securely adhering polypropylene to these polar substrates, like nylon, ethylene-vinyl alcohol copolymers (EVOH), polyvinyl alcohol polymers, metals,glass or wood, etc., is to blend a polypropylene grated with an unsaturated carboxylic acid or acid derivative with polypropylene and use this material directly as an adhesive layer between polypropylene and a polar suhstrate. It would sometimes be preferable to use polyethylene grafted with unsaturated carboxylic acid and acid derivatives because of ease in preparation relative to polypropylene graft copolymers.
If one blends the polyethylene graft copolymers with polypropylene, however, relatively poor adhesion is obtained to polar polymers and other polar substrates. In some instances no adhesion at all is obtained between the graft copolymer blend with polypropylene and the polar substrate. The blends of this invention overcome these dîfficultïes.
Ey grafting suitable unsaturated carboxylic acids or acid anhydrides to a polyethylene backbone and blending the resulting graft copolymer with a mixture of a polyethylene copolymer made by low pressure polymerization (~usually designated as linear low density polyethylene or LLDPE) and a polypropylene we have obtained compositions with excellent adhesive strength to both polypropylene and to various substrates including polar polymers like nylon, ethylenevinyl alcohol copolymers, polyvinyl alcohol polymers, and other polar surfaces such as metals, glass, cellophane, paper, wood and many others.

3~

~150~

The invention in its b~roader aspects comprehends a modified polyolefin adhesive blend comprising: (a) about 0.1-40 parts by weight in the blend of a graft copolymer of about 70-99.999 wt.~ of a polyethylene backbone grafted with about 30-0.001 wt.% of at least one grafting monomer compris-ing at least one polymerizable ethylenically unsaturated carboxylic acid or carhoxylic acid anhydride for a total of 100% and (b) about 99.9-60 parts by weight of a blending resin mixture of about 25-75 wt.% of a linear low density ethylene copolymer containing a higher olefin in addition to ethylene haYing a density of about 0.91 to less than O.q4 and a substantial absence of long-chain branching and about 75-2S wt.% of a propylene polymer for a total of lQ0~.
The invention also comprehends a composite structure comprisin~, a substrate, and adhered thereto the above modified polyolefin blend.
The invention further comprehends a composite structure comprising, two or more substrates with adjacent pairs adhered together by an intervening layer of such modified polyolefin blend.
The term polyethylene used herein for the grafting backbone includes homopolymers of ethylene and copolymers of ethylene with propylene, butene-l and other unsaturated aliphatic hydrocarbons. Also it is preferable sometimes to graft the blends of two or more of the above homopolymers and copolymers.
The term polypropylene used herein as part of the blending resin includes propylene homopolymers and copolymers of propylene with ethylene, butene and other unsaturated aliphatic hydrocarbons. They are usually prepared using transitional metal catalysts. Especially preferable in this invention are propylene homopolymers and propylene copolymers prepared by the so-called block copolymerization process. It is sometimes preferable to use blends of two or more of the above homopolymers or copolymers as the polypropylene component of the blending resln .

r~

~15{)8~2 The term polyethylene polymers used herein as a blending resin includes copolymers of ethylene with up to 40% of such higher olefins as propylene, butene-l, hexene-l, octene-l, etc. It is sometimes preferable to use blends of two or more of the above copolymers, as the polyethylene component of the blend-ing resin. Preferable ethylene copolymers are those prepared by the low pressure method which produce the so-called linear low density polyethylenes or low pressure low density polyethylenes (LPLDPE). Especi-ally preferable are those linear low density poly-ethylenes which have narrow molecular weight distri-bution.
These linear low density polyethylenes have lS a unique set of properties which distinguish them from both conventional low density polyethylene (LDPE) resins andhigh density polyethylene resins. Because of the methods by which low density polyethylenes are pre-pared, they are highly branched materials which have a tendency to coil on themselves and when stretched out snap back and exclude other materials. The linear low density materials, on the other hand, as their name indicates, have very little of this long-chain branching and have on the backbone just short-chain branches introduced by the use of a comonomer. For this reason these polymers have melting points approximately 15-20 higher than that of conventional LDPE resins.
This linear structure allows the polymer to stretch out better and also to blend more easily with other polymers having linear structure like polypropyl-enes, polyethylenes and polybutene-l, etc. The range of density for linear low density polyethylenes is from about 0.91 to less than 0.94. This distinguishes LLDPE from ~DPE which range from 0.94 to 0.97. The structure of the linear low density polyethylenes differs from the high density materials by the fact 115~3882 that they contain considerably more of the comonomer than the high density polyethylene copolymers leading to a high degree of short chain branching. This difference in structure causes their properties to differ from those of HDPE and LDPE.
Linearity leads to good tensile and tear-properties while branching yields toughness, puncture resistance and tear strength, low temperature impact, low warpage and excellent environmental stress crack resistance. These differences from conventional low density polyethylene and high density polyethylene have caused LLDPE to be called a third generation of polyethylene - a different material, actually a hybrid with its own set of properties. Because it has its own set of properties, one cannot per se extrapolate and predict the properties of this material, when combined with other polymers, on the basis of the behavior of HDPE or LDPE in blends. Hence, it was surprising to note that these materials, when combined with poly-ethylene-graft copolymers and polypropylene are able to yield properties which are not possible when using LDPE or HDPE combined in the same way with polypropyl-ene and a polyethylene-graft copolymer.
The backbone of the graft copolymers includes homopolymers of ethylene and copolymers of ethylene with up to 40 weight percent of such higher olefins as propylene, l-butene and l-hexene and may contain up to 5% of said di- or triolefins as are used commercially in ethylene-propylene terpolymers such as ethylidene-norbornene, methylenenorbornene, 1,4-hexadiene and vinylnorbornene. Also, it is preferable sometimes to graft to blends of two or more of the above homopoly-mers, copolymers and terpolymers. While the above polymers represent the preferred embodiments of our invention they should not be regarded as limiting the invention in any way.

`1151~88Z

The unsaturated carboxylicacidsor acid an-hydrides used as the grafting monomers include compounds such as acrylic acid, methacrylic acid, maleic anhy-dride, 4-methyl cyclohex-4-ene-1,2-dicarboxylic acid anhydride, bicyclo(2.2.2)oct-5-ene-2,3-dicarboxylic acid anhydride, 1,2,3,4,5,8,9,10-octahydronaphthalene-

2,3-dicarboxylic acid anhydride, 2-oxa-1,3-diketospiro (4.4)non-7-ene,bicyclo(2.2.1)hept-5-ene-2,3-dicarboxylic acid anhydride, maleopimaric acid, tetrahydrophthalic anhydride, x-methylbicyclo(2.2.1)hept-5-ene-2,3-dicar-boxylic acid anhydride, x-methylnorborn-5-ene-2,3-dicarboxylic acid anhydride, norborn-5-ene-2,3-dicar-boxylic acid anhydride, Nadic anhydride, methyl Nadic anhydride, Himic anhydride, methyl Himic anhydride and other fused ring monomers described in U.S. patents

3,873,643 and 3,882,194, both assigned to the assignee hereof.
Cografting monomers as described in U.S.
patent 3,882,194 are also useful for preparing the graft copolymers of this invention.
Included among the conjugated unsaturated esters suitable for cografting are dialkyl maleates, dialkyl fumarates, dialkyl itaconates, dialkyl mesa-conates, dialkyl citraconates, alkyl acrylates, alkyl crotonates, alkyl tiglates and alkyl methacrylates where alkyl represents aliphatic, aryl-aliphatic and cycloaliphatic groups containing 1-12 carbon atoms.
Esters particularly useful in the cografted copolymers of this invention are dibutyl maleate, diethyl fumarate and dimethyl itaconate. Among the acids and acid an-hydrides particularly useful in the cografted copolymers of this invention are maleic anhydride, tetrahydroph-thalic anhydride, x-methylbicyclo(2.2.1)hept-5-ene-2, 3-dicarboxylic acid anhydride and bicyclo(2.2.1~hept-5-ene2,3-dicarboxylic acid anhydride.
It is often desirable to use more than one monomer in either or both classes of monomers in order 115t~882 to control the physical properties of the final prod-ucts. The method in general consists of heating a mixture of the polymer or polymers and the monomer or monomers with or without a solvent. The mixture can be heated to above the melting point of the polyolefin with or without a catalyst. Thus, the grafting occurs in the presence of air, hydroperoxides, other free radical catalysts or in the essential absence of those materials where the mixture is maintained at elevated temperatures and (if no solvent is used) preferably under high shear.
The graft and cograft copolymers of this invention are recovered by any method or system which separates or utilizes the graft copolymer that is pro-duced. Thus, the term includes recovery of the co-polymer in the form of precipitated fluff, pellets, powders and the like, as well as further chemically reacted or blended pellets, powders and the like or in the form of shaped articles formed directly from the resulting copolymer.
Any of the commonly known hydroperoxides which have a half life of at least 1 minute at 145C.
may be used in the method of this invention. Such hydroperoxides have the general formula R-O-OH, wherein R is an organic radical. Among the suitable hydro-peroxides are t-butyl hydroperoxide, p-menthane, hydro-peroxide, pinane hydroperoxide, and cumene hydroperox-ide, as well as others known in the art. The elevated temperature causes rapid decomposition of the hydro-peroxide which catalyzes the reaction between thepolyolefin and monomer to form the graft copolymcr.
Obviously, the more homogeneous the mixture prior to heating, the less mixing will be required of the solution or molten composition. Generally, in order to obtain a desirable conversion, it has been found that some form of mixing is highly desirable in the absence of a solvent even when a uniform mixture 115{3882 of all of the components of the composition is formed prior to heating. In general, when a solvent is not used, the composition should be heated to a tempera-ture above about 130~C. and it is preferred to use the temperatures ranging from about 200-360C. Tempera-tures substantially above about 360C. are generally to be avoided in order to avoid substantial decomposi-tion of the polymeric ingredients. However, if the decomposition products are not undesirable in the prod-uct, as in the production of high melt index waxes, higher temperatures may be employed. The reaction time required is quite short, being`of the magnitude of from a few seconds to about twenty minutes, although extended heating times do not substantially affect the product and may be employed when desired for any reason.
A convenient method of accomplishing the reaction is to premix the ingredients and then extrude the composition through a heated extruder. Other mix-ing means, such as a Brabender mixer, a Banbury mixer, roll mills and the like may also be employed for the process. In order to prevent undue increase in molecu-lar weight with a possibility of some crosslinking at elevated temperatures, it is desirable to carry out the reaction in a closed vessel. A conventional single or multiple screw extruder accomplishes this result without the use of auxiliary equipment and for this reason is a particularly desirable reaction vessel.
The resulting copolymers of this invention are found to consist of about 70-99.95 weight percent of polyethylene and about 0.05-30 weight percent of the unsaturated acid or acid anhydride or mixtures.
The cograft copolymers of this invention con-sist of about 50-99.9 weight percent of polyolefin, about 0.05-25 weight percent of the unsaturated acid or acid anhydride or mixtures thereof and about 0.05-25 weight percent of the unsaturated ester and mixtures thereof. These resulting graft copolymers are capable of being blended or reacted with a wide variety of other materials to modify the copolymer further.
The blends of this invention can be used to join polypropylene to a number of polar materials or it can be used to join two polar materials together.
The methods for this joining can be lamination, co-extrusion, extrusion lamination, coextrusion coating or any other method for joining dissimilar materials known to those skilled in the art. Some of these com-positions are polypropylene/adhesive of this invention/nylon, polypropylene/adhesive/ethylene-vinyl alcohol copolymer, polypropylene/adhesive/aluminum, polypropyl-ene adhesive/steel, polypropylene/adhesive/glass, polypropylene/adhesive/wood, polypropylene/adhesive/
leather, polypropylene/adhesive/nylon/adhesive/poly-propylene, and polypropylene/adhesive/EVOH/adhesive/
polypropylene.
Examples of other metal combinations are aluminum/adhesive/aluminum or adhesive/aluminum/adhe-sive or polypropylene/adhesive/aluminum/adhesive/poly-propylene. Other metals such as copper, steel, brass, etc., can also be used. Dissimilar metal examples are:
aluminum/adhesive/copper, aluminum/adhesive steel, aluminum/adhesive/brass, etc. One could also have combinationsin which one has a metal/adhesive/polar polymer. Examples of these would be aluminum/adhesive/
nylon or aluminum/adhesive/EVOH, or steel/adhesive/
nylon/adhesive/steel. Here, again, one skilled in the art can find a number of obvious combinations from the principles described above.
These materials can be used to manufacture many different useful articles. They can be used as packaging film, blow molded bottles, coextruded sheet which can be thermoformed into containers, coatings on glass bottles or wood or metal or even to join two metals, either the same metal or dissimilar metals, into a lamination. ~

g Blends of the graft copolymers with poly-propylene and LLDPE follow the similar procedures as those used in U.S. patents 4,087,587 and 4,087,588, both assigned to the assignee hereof. It is preferred S in this invention first to prepare a polyethylene in which an unsaturated monomer is grafted in a high con-centration and then the grafted polyethylene can be blended with a wide variety of non-grafted PP and LLDPE
so that we can control not only the amount of graft copolymer in the blend but also properties of the blends. The amount of graft copolymer in the blend is determined by the amount required to attain maximum adhesion with the substrate being used.
In preparing the blends in the examples below from the above graft copolymers, polypropylene, ethyl-ene homopolymers and copolymers, any blending equipment or technique may be used. As an example, blends can be prepared in an electrically heated Brabender Plasti-corder mixing head using a scroll-type mixer under the following conditions: temperature = 400F., rotor speed = 120 rpm and mixing time = 10 minutes after flux.
All blends contain an antioxidant, e.g., 1,000 ppm tetrakis [methylene 3-(3',5'-di-tert butyl-4'-hydroxyphenyl)proprionate] methane and 2,500 ppm di-stearyl thiodiproprionate.
In specific examples, the resultant blendswere compression-molded into films approximately 0.005-0.007 inches thick. The films were then heat-sealed to the substrate under evaluation at an appropriate temperature and time. These exemplary conditions are for:
1. Nylon 6 - 430F. and 2 seconds 2. Ethylene-vinyl a~cohol copolymer (EVOH) - 430F. and 5 seconds 3. Polypropylene - 500F. and 5 seconds

4. Aluminum - 430F. and 2 seconds The resultant composites were tested by cutting into 115~88Z

strips one inch wide. Adhesion is then tested by a T-peel test similar to that described in ASTM D 1876-72.
Example 1 X-methyl bicyclo(2.2.1)hept-5-ene-2,3-dicar-S boxylic acid anhydride (XMNA) is reacted with a highdensity polyethylene homopolymer resin in a twin screw extruder to give a graft copolymer resin with 1.5 wt.%
XMNA incorporation and a melt index of 1.6 gllO min.
The graft copolymer is blended in varying amounts with a random propylene-ethylene copolymer having a melt flow rate (~R) of 2. T-peel adhesion results are summarized below: -Graft Copolymer in Blend Adhesion to Nylon 6 (wt.%) (lbs/in) lS 3 0 Adhesion of these blends to polypropylene is excellent (>10 lbs/in).
Example 2 Using the same graft copolymer as described in Example 1, blends were prepared with a propylene-ethylene block copolymer having an MFR of 2. T-peel adhesion results are summarized below:
Graft Copolymer in Blend Adhesion to Nylon 6 (wt.%) (lbs/in) ' 0.3 0.0 Example 3 The same blends as used ~n Example 2 were heat-sealed to an ethylene-vinyl alcohol copolymer (EVOH). All these blends give extremely poor adhesion to EVOH. The samples could not be tested because they fell apart.
Example 4 2~inety percent of a propylene-ethylene block copolymer containing 7.8% ethylene with an MER of 3.4 115~88Z

was blended with 10 wt.% of the same graft copolymer as described in Example 1. This blend, when heat-sealed to EVOH and nylon 6-, gives poor heat seal adhesion.
Example 5 When 90% of a polypropylene homopolymer having an MFR of 4 blended with 10% of the same graft copolymer as described in Example 1 was heat-sealed to EVOH the resultant heat seal adhesion is 0.1 lb/in.
If this same blend were heat-sealed to a randon poly-propylene copolymer as described in Example 1, its adhesion is greater than 10 lb/in.
The above examples show that if a polyethyl-ene graft copolymer is blended with a polypropylene lS homopolymer, a random PP copolymer or a block PP co-polymer the adhesion is not satisfactory to polar polymers.
Example 6 A blend is prepared of a polypropylene block copolymer, a linear low density polyethylene and the graft copolymer described in Example 1. The polypro-pylene block copolymer contains ethylene, has an MFR
of 2 and a density of 0.902. The linear low density polyethylene contains butene-l, has an MI of 3 and a density of 0.922. The adhesion of blends containing various proportions of these materials are tested to nylon 6, EVOH and to a random polypropylene copolymer.
The results are shown in Table I.
TABLE I
Adhesion ~raft Nylon 61 Evo~2 pp3 PP LLDPE Copolymer lbJin lb/in lb/in .
90 -- 10 0.0 0.1 >10.0 65 25 10 2.1 1.2 >7.4 50 40 10 3.3 4.3 - 4.8 45 45 10 3.7 4.5 4.4 40 50 10 4.4 5.9 4.2 ~lS~)~82 25 65 10 >8,7 8.6 0.5 -- 90 10 ~6.5 >8.1 0.8 1. 1 mil of nylon 6 is heat-sealed to 5-7 mil of the adhesive blend on a heat sealer at a set temperature of 430F. for 2 sec. The nylon 6 is closest to the heated jaw.
2. 5-7 mil of the adhesive blend is heat-sealed to

5-7 mil of EVOH at a heat sealer set tempera-ture of 430F. with the following order of layers starting with the upper heated jaw: 3 mil Mylar~, adhesi~e blend, ~VO~.
3. 5-7 mil of adhesive blend is heat-sealed to 5-7 mil of PP at a set temperature of 500~F. for 5 sec. with the following order of layers starting with the upper heated jaw: 10 mil Teflon*, adhesi~re blend, PP, 10 mil Teflon.
It can be seen that there is a range of com-positions containing <65% polypropylene and >25% poly-propylene in which satisfactory adhesion to all three substrates can be obtained.
Example 7 Blends containing the same graft copolymer as described in Example 1, the polypropylene block copoly-mer described in Example 6 and a polyethylene homopoly-mer made by the high pressure method, having a melt index of 1.8 and a density of 0.922, are prepared.
T-peel adhesion to nylon 6, EVOH and the polypropylene random copolymer are shown in Table II.
TABLE II
Adhesion Nylon 6 EVOH PP
PP LDPE Copolvmer lbJin lb/in lb/in -- 10 0 . O ' O . 1 >10 2.2 0.6 >10 1.~ 1.4 5.6 -- 3.5 0.4 -- 90 10 4.1 -- 0.0 Comparison of the T-peel adhesions obtained in Example 6 to those of Example 7 show that linear low density polyethylenes give far superior adhesion re-* denotes Trademark liS~88;~

sults in comparison to those blends containing ordi-nary low density polyethylene.
Example 8 A blend is prepared containing 45% of a polypropylene block copolymer (MFR = 2, density =
0.922), 45% of a linear low density polyethylene (MI =
3, density = 0.922) and 10% of the graft copolymer described in Example 1. The blend (5-7 mil) is heat-sealed to 1 mil of "A wettability" aluminum at 430F.
and 2 seconds. The T-peel adhesion is 3.4 lb/in.
Exa~ple 9 Maleic anhydride is reacted with a polyethyl-ene resin in a twin screw extruder to give a graft co-polymer resin incorporating maleic anhydride. 10% of this graft copolymer is blended with 45% of a propylene-ethylene block copolymer having an MFR of 2 and 45% of a linear low density polyethylene with a melt index of 3. This material is adhered to various substrates with the following results in T-peel adhesion:
- Adhesion Substrate lb/in ~ EVOH 6.3 pP 3.5 Example 10 Bicyclo(2.2.1)hept-5-ene-2,3-dicarboxylic acid anhydride is reacted with a high density poly-ethylene homopolymer resin in a twin screw extruder to give a graft copolymer with incorporation of the unsat-urated anhydride described above. 10 wt.% of this graft copolymer is blended with 45 wt.% of a pr~pylene-ethylene copolymer having an MFR of 2 and 45 wt.% of an LLDPE with a melt index of 3. The T-peel adhesion results are summarized below:
Adhesion Substratelb/in -EVOH 7.2 pp 2.7 Example 11 A trilayer composite is prepared by heat-sealing at 500F. for 5 sec. the following layers:
nylon 6, a polypropylene adhesive of this invention (10 wt.% of the graft copolymer described in Example 1, 45 wt.~ of a block polypropylene copolymer and 45~-of a linear low density polyethylene), and a random copoly-mer of propylene and ethylene. The layers are arranged in the order given, i.e., nylon/adhesive/PP. The adhesion of the nylon to the adhesive layer is 2.7 lb/
in with film tear and the adhesion of the adhesive layer to the polypropylene is 3.7 lb/in.
Example 12 A similar construction as described in Example 11 was prepared using EVOH in place of poly-propylene. The T-peel adhesion obtained to the nylon layer is 2.7 lb/in with tear of the nylon layer, and to EVOH is 7.5 lb/in with tear of the EVOH layer.
Example 13 A construction of three layers was prepared in the heat sealer at 500F. and 5 sec. using polypro-pylene/adhesive layer/EVOH as the trilayer composition.
The adhesive layer is as described in Example 11. The T-peel adhesion results are:
Adhesion Substrate lb/in PP 3.8 EVOH 5.1 Example 14 A trilayer construction of PP/adhesive layer/
aluminum was prepared in the heat sealer at S00F. and 5 sec. The adhesive layer is as described in Example 11. The following T-peel adhesion results were obtained:
Adhesion Substrate lb/in pp 4.0 EVOH 4.5 ` 115~8~Z

Glossary of Terms EVOH - ethylene-vinyl alcohol copolymer HDPE - high density polyethylene LDPE - low density polyethylene LLDPE - linear low density polyethylene LPLDPE - low pressure low density polyethylene MFR - melt flow rate, ASTM d 1238, condition L
MI - melt index, ASTM D 1238, condition E
PP - polypropylene XMNA - x-methylbicyclo(2.2.1)hept-5-ene-2,3-dicarboxylic acid anhydride Having described our invention as related to the embodiments set out herein, it is our intention that the invention be not limited by any of the details of description, unless otherwise specified, but rather be construed broadly within its spirit and scope as set out in the appended claims.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A modified polyolefin adhesive blend comprising:
(a) about 0.1-40 parts by weight in said blend of a graft copolymer of about 70-99.999 wt.% of a polyethylene backbone grafted with about 30-0.001 wt.% of at least one grafting monomer comprising at least one polymerizable ethylenically unsaturated carboxylic acid or carboxylic acid anhydride for a total of 100% and (b) about 99.9-60 parts by weight of a blending resin mixture of about 25-75 wt.% of a linear low density ethylene copolymer containing a higher olefin in addition to ethylene having a density of about 0.91 to less than 0.94 and a substantial absence of long-chain branching and about 75-25 wt.% of a propylene polymer for a total of 100%.

2. The blend of claim 1 wherein said propylene polymer comprises propylene homopolymers and copolymers of propylene and one or more unsaturated aliphatic hydrocarbons.

3. The blend of claim 1 wherein said propylene polymer comprises a copolymer of propylene and ethylene.

4. The blend of claim 1 wherein said linear low density ethylene copolymer has a density of about 0.91 to less than 0.94.

5. The blend of claim 4 wherein said linear low density ethylene copolymer has a narrow molecular weight distribution.

6. The blend of claim 2 wherein said hydrocarbon comprises ethylene.

7. The blend of claim 1 wherein said ethylene copolymer blending resin comprises copolymers of ethylene and an unsatu-rated hydrocarbon.

8. The blend of claim 7 wherein said hydro-carbon comprises propylene, butene-1, hexene-1 or octene-1.

9. The blend of claim 7 wherein said hydro-carbon comprises propylene, butene-1, hexene-1 or octene-1 in an amount up to about 40 wt.% of said copolymer.

10. The blend of claim 1 wherein said graft-ing monomer comprises at least one of acrylic acid, methacrylic acid, maleic acid, itaconic acid, citra-conic acid, mesaconic acid, maleic anhydride, 4-methyl cyclohex-4-ene-1,2-dicarboxylic acid anhydride, bicyclo (2.2.2)oct-5-ene-2,3-dicarboxylic acid anhydride, 1,2, 3,4,5,8,9,10-octahydronaphthalene-2,3-dicarboxylic acid anhydride, 2-oxa-1,3-diketospiro(4.4)non-7-ene, bicyclo(2.2.1)hept-5-ene-2,3-dicarboyxlic acid anhy-dride, maleopimaric acid, tetrahydrophthalic anhydride, norborn-5-ene-2,3-dicarboyxlic acid anhydride, Nadic anhydride, methyl Nadic anhydride, Himic anhydride, methyl Himic anhydride, and x-methyl bicyclo(2.2.1) hept-5-ene-2,3-dicarboxylic acid anhydride.

11. A composite structure comprising:
(A) a substrate, and adhered thereto (B) a modified polyolefin blend according to claim 1.

12. The composite structure of claim 11 wherein said substrate comprises polar polymers, solid metals, glass, paper, wood or cellophane.

13. The composite structure of claim 11 wherein said substrate comprises nylon.

14. The composite structure of claim 11 wherein said substrate comprises aluminum.

15. The composite structure of claim 11 wherein said blend is according to claim 2.

16. The composite structure of claim 11 wherein said blend is according to claim 3.

17. The composite structure of claim 11 wherein said blend is according to claim 4.

18. The composite structure of claim 11 wherein said blend is according to claim 5.

19. The composite structure of claim 11 wherein said blend is according to claim 6.

20. The composite structure of claim 11 wherein said blend is according to claim 7.

21. The composite structure of claim 11 wherein said blend is according to claim 8.

22. The composite structure of claim 11 wherein said blend is according to claim 9.

23. The composite structure of claim 11 wherein said blend is according to claim 10.

24. The composite structure of claim 11 wherein said substrate comprises ethylene-vinyl alcohol copolymer.

25. A composite structure comprising:
(A) two or more substrates with adjacent pairs adhered together by (B) an intervening layer of a modified poly-olefin blend according to claim 1.

26. The composite structure of claim 25 wherein said (A) comprises polypropylene and a polar substrate.

27. The composite structure of claim 25 wherein said (A) comprises polypropylene and a nylon.

28. The composite structure of claim 25 wherein said (A) comprises polypropylene and ethylene-vinyl alcohol copolymer.

29. The composite structure of claim 25 wherein said (A) comprises polypropylene and aluminum.

30. The composite structure of claim 25 wherein said (A) comprises polar substrates.

31. The composite structure of claim 25 wherein said blend is according to claim 2.

32. The composite structure of claim 25 wherein said blend is according to claim 3.

33. The composite structure of claim 25 wherein said blend is according to claim 4.

34. The composite structure of claim 25 wherein said blend is according to claim 5.

35. The composite structure of claim 25 wherein said blend is according to claim 6.

36. The composite structure of claim 25 wherein said blend is according to claim 7.

37. The composite structure of claim 25 wherein said blend is according to claim 8.

38. The composite structure of claim 25 wherein said blend is according to claim 9.

39. The composite structure of claim 25 wherein said blend is according to claim 10.

40. The composite structure of claim 11 wherein said substrate comprises propylene homopolymers and copolymers of propylene and one or more unsaturated aliphatic hydrocarbons.