CA1083291A - Adhesive blends - Google Patents

Abstract

Abstract of the Disclosure Compositions of matter having among other desirable characteristics strong adhesive properties to various substrates, these compositions comprising blends of a graft copolymer of a high density polyethylene and at least one unsaturated fused ring carboxylic acid anhydride blended with a polyethylene resin of one or more homopolymers of ethylene, copolymers of ethylene and an alpha-olefin or any or all of these.

Description

ADI~ ES I VE B LENDS
Background of the Invention various polymer and resin mixtures have been proposed for adhesives witll strong bonding properties for various substrates and these have been successful to varying degrees.
~lowever, the blends of this invention have remarkably superior properties when used as adhesives. Thus the object of this invention is to provide modified polyolefin resins with improved adhesion to substrates such as polar polymers, metals, glass, paper, wood, etc. These resins can be applied in any conventional manner and typical application processes are lamination, extrusion coating, coextrusion, powder coating, blow molding, etc.
It is well known that laminates of polyolefins with dissimilar substrates have many desirable characteristics.
Among these are heat sealability and barrier properties.
However, it is often difficult to bond polyolefins to dissimilar substrates because of the differences in physical and chemical structures. To overcome the bonding difficulties, it has been proposed in the past to use either an adhesive layer between the polyolefin and the substrate or a more expensive, highly polar copolymer of the olefin such as an ionomer resin in place of the - conventional polyolefin. This latter is not entirely successful - because, although the ionomer resin may show good adhcsion, the bond formed is easily weakened by exposure to moisture or common solvents.
Another method for improving the adhesion of a polyolefin to a substrate is to graft polar functional groups onto the polyolefin backbone chain. The most common combination is maleic anhydride grafted to polypropylene. However, grafting - of maleic anhydride on a polyethylene backbone when applicd as in this invention does not give the adhesive power of the products of this invention.

'; . -1- $~

;
.~ . .

1~83Z91 Summary of the Invention .
By grafting suitable unsaturated fused ring carboxylic acid anhydrides to a high density polyethylene and blending the resultant graft copolymer with a polyethylene resin that is either a homopolymer of ethylene, a copolymer of ethylene and an alpha-olefin, or a terpolymer of ethylene, an alpha-olefin and a diene or a mixture of these, we have obtained composites with excellent adhesive strength to various substrates including polar polymers, metals, glass, paper, wood and the like. These composites also have exceptional heat sealability. Furthermore the adhesive bond formed is not easily affected by moisture or common solvents. Surprisingly, the adhesive strength of the blends is synergistic in that it is better than that of either component when tested alone. This occurs despite the fact that - ;
the concentration of fused ring, carboxylic acid anhydride in the blends is reduced by dilution with the ungrafted resin component.
The blends of graft copolymer and ethylene polymer or copolymer of this invention have improvements over previous .
systems of which applicants are aware and these improvements include: eliminating the need for additional adhesive layers when bonding unmodified polyolefins to dissimilar substrates-;
: :
economic advantages due to eliminating the need to use costly, - -highly polar copolymers of olefins; excellent bond stren-~tll; ~lld -~ -~ - .
`~ - moisture and solvent insensitivity of the adhesive bond between the blends of this invention and various substrates.
,~ According to this invention, there are provided blends of polyethylene polymers with copolymers comprising polyolefins which are modified by grafted unsaturated fused rin~, carboxylic acid anhydride~monomers to exhibit improved adhesion to various substrates.
I~
More particularly the invention pertains in one aspect 3 to a modified polyolefin blend having improved adhesion to :: A
. ~ ' .
......
..:... , ~ : . ` ,............ .
.... ... ,.............. .. :, . . .

1083Z9l various substrates and consistillg essenti~lly of a~ut ~.]-~
parts by weight in the blend of a graft copolymer of about 70-99.999 wt. ~ of a high density polyethylene back~one grafted with about 30-0.001 wt. ~ of at least one compound containing at ]east one member of the group consisting of unsaturated acyclic, carbocyclic, heterocyclic, and polycyclic moieties which are fused to at least one carboxylic acid anhydride-containing ring; and about 99.9-5 parts by wei~llt of a ~ ctll~l-ene resin selected from the class consisting of homopolymers of ethylene, copolymers of ethylene and alpha-olefin, terpolymers of ethylene, alpha-olefin and diene and mixtures of these poly-ethylene resins.
Another aspect of the invention comprehends a composlte structure comprising a solid substrate, and adhered thereto a modified polyolefin blend according to the above.
When a high density polyethylene polymer or copolymer is applied to a substrate such as aluminum or nylon, little or no adhesion is seen as is well known in the art. When a poly-ethylene graft copolymer prepared, for example, according to U.S. Patent 3,873,643 or 3,882,194, is applied to nylon, the adhesion ia poor, but when a blend of a graft copolymer and --high density homopolymer is applied to nylon, the resulting blend has excellent adhesion to nylon. Surprisingly, the ad-hesion of the blends is better than that of either component when tested alone This occurs despite the fact that the concent~ation of the graft copolymer in the blend is reduced by dilution with the ungrafted resin component. Similarly, the same synergistic effect of increased adhesion is observed when using ethylene-~, hexene-l copolymer, ethylene-propylene-diene terpolymer, low `; 30 .

~,. . ~.. . - - .

density poly~.hylene homopolymer or mixtures o~ any or all of these as blending resins~
The graft copolymers disclosed herein are described and c~ai~?d in the above U. S. Patents 3,873,643 and 3,882,194, both assigned to the assignee hereof.

, Description of the Prefer~ed Embodiments The term "high density polyethylene" used herein for the grafting backbone includes polymers of ethylene and copolym~rs with prop~lene, butene and other unsaturated aliphatic hydrocar-bons. Tnese high density polyethylenes and copolymers are prepared usually using transitional metal catalysts and are also often ~ ;
~ re~erred to as low or medium pressure polyethylenes as opposed -,~ to low density polyethylene which often involves high pressure `~' and free radical initiators. Pref~rably, such high density poly-~' ethylene has a density of about 0.930 - 0.970. Also, it is .:;
preferable sometimes to graft to blends of two or more of the above horopolymers and copolymers.
The term "polyolefin" used herein for the blending resin includes ethylene poly;ners and copolymers of ethylene with t . 20 propylene, butene and other unsaturated aliphatic hydrocarbons.
--~ Especially preferable in this invention are ethylene homopolymers prepared by either the low or hiyh pressure methods (linear or high density polyethylenes and branched or low density poly-ethylenes, respectively) and such copolymers of ethylene with up ' to 40 eight percent of such higher olefins such as propylene, butene and l-hexene and which may contain up to 5 weight percent of such di- or triolefins as are uscd comm~rcially in ethylene-propylene terpolymers such as ethylidenenorbornene, me~hylene-~',t~ norborneno, 1~ 4-hexadiene and vinylbornenc. It is prefcrable So~e~tim2s to use blends of two or more of the above homopolymers, copol~mers and terpolymers as the blendin~ resin.
" ~
.

... _~_ 1~83Z9l The u~satu~ated Lused ring carhoxylic acid anhyarides us~d as the grafting monomers are compounds which contain one or mor~ carbocyclic, acyclic, polycyclic and/or heterocyclic moieties not includi~ the anhydride ring.
Fused ring is d~fined in the "International Encyclopedia of Chemical Science, D. Van Nostrand Co., Inc., Princeton, New Jersey, 196' a, "a structural ~lement in the formula of a chemical com~ound consisting of t~;o rings that are joined by having two atoms in com~on". ~ - ~
Tne compounds may be simplet bridged, carhocyclic, ~ -heterocyclic, polycyclic or complex. These compounds may contain ~`
up to 35 car~on atoms. These classes are represented respectively by the follo,ring structures which are meant to be illustrative rather tnan limiting:

~ :
.,ij ~ .

... ~ .

.",~` `' , .
j , ~1 ,i;~`
~';' ~ ~j .

, ' ~
'`` !

.... . . . .

~83291 .

, .. . .
~ o , ~ -, .,., ", ,~ ~ o ~\v ~ ~ o~ U
R Q 'O

.. ~ ~ 'd O O ~d ~ ~1 a a) ~ ~ ~ ~ m .,~ ~ ~ ~æ
. ~ ~ ~ ~ ~d --X `-'. ~ ~ X ~ ~ o O
: ~ ~Q r Q Q
~, h O O
r~ rl ~, Q ~d , Q 'd .~ .
J
~ d o~ ~ X ~

~ ~} e ~ 0 ~ u 'd ~ O ~ .
\ 'd \~ X
P~ R
,'.`

'a o ~

~, A ~ / A N ~ o U U

Qh ~\ ' ` ` ~ .0 ~ 3 Q 3 ~ ~ ~, ~ x a) ~

,;

1083Z9l It is often desirable in making the graft copolymers to use more t~an one monomer in order to control the physical p~operties of the final graft copolymers.
The method of making the graft copoiymers of the blends of this inven'cion consists in general of heating a mixture of the polymer or polymers and the monomer or monomers to be grafted in a solvent or above the melting point of the polyolefin with or without an initiator. Thus, the grafting occurs in the presence of air, hydroperoxides, other free radical initiators or - 10 in the essential absence of these materials where the mixture is maintained at elevated temperatures and preferably under high shear.
In ma'.~ing the graft copolymers used in this invention, the mixture of high density polyethylene or its copolymers and .....
monomer or monomers is heated in a solvent or above the melting point of the polyethylene at reaction temperatures and under reacting conditions described below and thereafter the resulting graft copolymer is recovered for later blending with the poly-ethylene resin. The term "recovered" means any method or system which separates the graft copolymer that is produced. Thus, the term includes recovery of the copolymer in the form of precip- ~;
itated fluff, pellets, powders and the like. -Any of the commonly known hydroperoxides which have a half life of at least one minute at 145C. may be used as an initiator. Such hydroperoxides have the general formula R-O-OH
wherein R is an organic radical. Among the suitable hydro-s ~ peroxides are t-butyl hydroperoxide, p-menthane hydroperoxide, pinane hydroperoxide, and cumene hydroperoxide, as well as others known in the art. The elevated temperature causes rapid decom-position of the hydroperoxide which initiates the reaction `i between the polyolefin and monomer to form the graft copolymer.
.

. , ~ , ~, _,,~. . - - --~;. . , . . :~

Obviously, the more homogeneous the mixture prior to heating, the less mixing will be required of the solution or molten co~position. Generally, in order to obtain a desirable conversion, it has been found that some form of mixing ic highly desirable in the absence of a solvent even when a uniform mix-ture of all of the components of the composition is formed prior to heating. In general, when a solvent is not used, the compo-sition should be heated to a temperature above about 130C., and -it is preferred to use the temperatures ranging from about 200C.
to about 360C. Temperatures substantially above about 360C.
are generally to be avoided in order to avoid substantial decom-position of the polymeric ingredients. The reaction time required ~;
is quite short, being OL the magnitude of from a few seconds to about 20 minutes, although extended heating times do not substan-,., tially affect the product and may be employed when desired.
A convenient ~.ethod of accomplishing the grafting reaction is to premix the ingredients and then extrude the com-~ position through a heated extruder. Other mixing means, such ,; as a Brabender/mixer, a Banbury/mixer, roll mills and the like may also be employed for the process. In order to preventundue increase in molecular weight with a possibility of some cross-linking at elevated temperatures, it is desirable to carry out the reactlon in a closed reactlon vessel. A conventional - single or multiple screw extruder accomplishes this result without the use of auxiliary equipment a~ for this reason is a partic-ularly desirable reaction vessel, although it is by no means ., ~ .

` necessary.

~ he resulting graft copolymers used in the blends of .~:
this invention are found to consist of about 70-99.999 weight per-cent of hish density polyethylene or copolymers and about 30-0.001 weight percent of the unsaturated fused ring carboxylic acid .: ~

,:

.
. ~._.. , .. . . .. - - :. .
:~.~ . .

1(~8329~
anhydride, ~sp~cially prererr~d is about 0.001-5 wt.~ o~ anhydridc in the graft co?olymer, 2ncl thcs~ resulting cJr~f t copolymers ~r~c capable of blending with a ~:ide variety of polyethylene resins to procluce th adhesive com?ositions of this invention.
Excellent mono~c~rs in the graft copolymcr of this in-vention include ~-methylcyclohex-~-en~-1,2-dicarboxylic acid anhydride, tetrahydrophth~.lic anhyclricle, x-methylnorborn-S-c~ne-

2,3-dicarboxylic anhydride, norborn-5-en2-2,3-dicarboxylic an-hydride, maleo-?imaric acid, and bicyclo(2.2.2)oct-5-ene-2,3-dicarboxylic anhydride.
It is preferrecd in this in~ntion first to prepare a high density polyethylene in which a graft monomer is grafted in a high concentration and then the modified polyethylen~ can then ., be blended ~ith a wide vzriety of non-grafted polyolefins 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 t~i.h the substrate being used. These substrates include polar polymers, wood, metal, glass, cellophane, ,~ .
, 20 paper and many others.
; The following ex.amples illustrate the preparation of the graft copolymers of ihe bl~nds of this inv~ntion and the ~ethods by wnich they are ~ade.

Example 1 n electrically heated C. W. Brabender, Inc. mixing head was modifi~d so that it could hold pressure. To this reactor was charged a mi~:ture of R.36 ~arts of NBDA, 0.68 parts of t-butyl hydroperoxide (TBHP) and 90.96 parts of a high density polyethylene powder havincJ an ~ILMI of 7. Th~ reactor was closcd, purged with . ~ .

., ~ .
;
'`'`
?
.. ~. . . . , - .: . ~
.. . . . . . .

1~83Z9l nitro~en and vacuumed until free of oxygen and heated to 260C.
After reaching 160C. agitation was started at 160 rpm. After 15 minutes at 260C. and 160 rpm, the mixture was cooled, quenched in cold hexane, dissolved in trichlorobenzene at 130~C. precip-itated in cold methylethylketone and dried at 95C. and 0.2 mm mercury absolute pressure overnight. The product contained 1.68 weight percent NBDA by elemental analysis. The HLMI of the product was 0.11. For higher MI products, a higher shear reactor can be used as shown in the following Examples 2 through 13.

Example 2 The same equipment as in Example 1 was charged with ~ 8.36 parts of NBDA and 91.64 parts of the polyethylene of Example : 1. The conditions now were 300-310C. at 275 rpm for 15 minutes in an oxygen-free atmosphere. The product, after recovery in the same manner, contained 4.75 weight percent NBDA by elemental analysis and the HL~II was 1.83. Thus, at the higher temperature and rpm, graft level and HLMI are higher.

Examples 3 (Comparative) and 4 ~ Under the same conditions as Example 2, except that `~ 20 the reaction times were only 5 minutes, maleic anhydride (M~) and XWNA were grafted to a polyethylene of HLMI = 7 with the results t~ shotm in Table I.

~ TABLE I
~' ~` , .
Wt.% Wt.~
Example Anhydride Grafted Product No. Anhydride Charged Anhydride HLMI

3 MA 5.00 2.62 1.50

4 X~L~A 9.08 1.56 12.08 .,. ~ .
~ The product of XMNA grafting is clearly more processable .
than the product of ~A grafting. When MA was reacted for 15 min-utes as in Example 2, the product HLMI was too low to measure.
.: .

' ~ -10-`' : ....
.:, .
.. . .

1~)8329~
Examples 5 through 8 Under the same conditions and in the same equipment as in Exam?le 2, a variety of fused ring anhydrides were grafted to polyethylene with the results shown in Table II.
In all cases, the ~ILtlIs of the graft polymer product were higher than the starting polyethylene.

TABLE II

Wt. % Wt.%
Example Anhydride Anhydride Grafted Product No. ~Ionomer Chargedl Anhydride2 HLMI
S X~A 9.08 3.018.26 6 4-.lTHPA8.47 1.1120.38 7 BOD~ 9.08 3.989.01 8 Maleo- 20.42 2.3410.57 Pimaric Acid Amounts charged are equimolar and equivalent to

5.0 weight percent MA.

2After solution and precipitation as in Example 1 to remove monomers and ungrafted homopolymers. -- -' ~

Example 9 A mixture ol 15 pounds tetrahydrophthalic anhydride , . - - .
; (THPA) and 150 pounds of high density polyethylene (7HLMI) is prepared by spraying an acetone solution of THPA onto the high -~ density polyethylene powder of Example 1 followed by evaporation of the solvent. This mixture is fed to a corotating twin-screw extruder e~uipped with five heating zones. The feed rate is ~ about 50 pounds per hour (pphl and the screw speed is 300 rpm.
,` The temperature profile is Zone 1 = 200C., Zone 2 = 270C., Zone 3 = 320C., Zone 4 = 270C., Zone 5 = 230C., and die !
temperature = 180C. To Zone 2 is added a mixture of catalyst (TBHP) and solvent (o-dichlorobenzene, ODCB) at a rate of about .~ .

1083Z9l 0.3 p?h TBHP and 3.1 pph ODCB. The reaction mixture is de-volatilized at Zone 4.
The properties of the resulting polyethylene/THPA
gra~t co~olymer are shown below:
Percent THPA incorporation 0.5 ; Melt Index 0.24 Tensile yield, psi 4560 Tensile break, psi 3290 Elongation, percent 850 10 Example 10 A mixture of 15 pounds NBDA and 150 pounds high density .. . .
polye',hylene (7 H~lI) is prepared by spraying an acetone solution of ~3D.~ onto the high density polyethylene powder of Example 1 follo;ed by evaporation of the solvent. This mixture is fed to a corotating twin-screw extruder equipped with five heating zones.
The temperature profile is Zone 1 = 200C., Zone 2 = 270C., Zone 3 = 320C., Zone 4 = 270C., Zone 5 = 230C. and die temperature = 180C. To Zone 2 is added about 0.4 pph TBEIP and 4.7 pph ODCB.
The reaction mixture is devolatilized at Zone 4.
The properties of the resulting polyethylene/NBDA graft co~ol~er are shown below~
., :"~
i`~ Percent NBDA incorporation 3.3 r,;~ ~ Melt Index 0.16 Tensile yield, psi 4030 Tensile break, psi 2630 Elongation, percent 400 ....
Example 11 High density polyethylene (7 HLMI) is fed to a corotatiny twin-screw extruder equipped with five heating zones. The feed rate is about 50 pph and the screw speed is 225 rpm. The temper-ature ?rofile is Zone 1 = 200C., Zone 2 = 270C., Zone 3 = 320C., ~ Zon~ 4 = 270C., Zone 5 = 230C. and die temperature = 180C.
.,~ , To Zone 2 is added a mixture of XMNA and t-butyl hydroperoxide (TBH?) at a rate of about 6 pph XMNA and 0.3 pph TBHP. The re-actio~ mixture is d~volatilized at Zone 4.

~.`
.~^.; .

~.

1~}83Z~

Tne properties of the resulting polyethylene/XMNA
g~aft copoly.~er are shown below:
Percent XMNA incorporation 1.8 ~lelt Index 0.28 Tensile yield, psi 4090 Tensile break, psi 2560 Elongation, percent 1020 Exa~les 12 and 13 High density polyethylene (7 ~LMI) and, respectively, tetrahydro?htnalic anhydride and bicyclol2.2.1)hept-5-ene~2,3-dicarboxylic acid anhydride are fed as dry blends to a corotating twin-screw extruder equipped with five heating zones. The feed ; rates are ~0 p?h of resin and 5 pph of anhydride. One percent ; by weight of TBHP catalyst as a 10% solution in ODCB is fed into Zone 2. T:~e screw speed is 300 rpm. The temperature profile is Zone 1 = 200C., Zone 2 = 270C., Zone 3 = 320C., Zone 4 = 270C., Zone 5 = 230C. and die temperature = 180C. The reaction mixture is devolatilized at Zone 4 and recovered.

Exam?les 14-16 A high density ethylene-hexene-l copolymer (8 HLMI, 0.943 density) is fed to a corotating twin-screw extruder equipped with five heating zones. The feed rate is about 50 pph and the screw speed is 250 rpm. The temperature profile is Zone 1 = 200C., Zone 2 = 270C., Zone 3 = 320C., Zone 4 =
270C., Zone S = 230C. and die tempera~re = 180C. The monomer(s) with dissol-.ed catalyst are added to Zones 2 and 3 at equal rates.
~`~ The mixture is devolatilized at Zone 4.
onomer feed concentrations and properties of the graft .~
~ copolymers are given below: ~
,, ~
:~ .

.
.,` ' ' :
, .. , . - . . . .: .

- TAB LE I I I
FEED GRAFT COPOLYMERS
Exam. ~A DBM TBHP
No. Wt.% Wt.% Wt.% M. I . % XMNA ~ DBM

14 3.8 none none 0.66 1.2 none 3.0 4.9 0.25 0.83 1.5 0.2 16 3.0 15.2 0.75 0.64 1.4 1.1 Thus, cografting is readily achieved with XMNA and ~;

dibutyl maleate (DBM).

Exam~le 17 -An electrically heated C. W. Brabender, Inc. mixing head was modified so that it could hold pressure. To this re-actor was charged a mixture of 5.0 parts of NBDA, 5.0 parts of diethyl fumarate (DEF), 0.1 part of TBHP and 89.9 parts of high density polyethylene ~7 HLMI). The reactor was closed, purged ¦ with nitrogen and vacuumed until essentially free of oxygen and heated to 300C. Agitation at 275 rpm was started when the ;, .
temperature reached 160C. After 15 minutes at 300C. and 275 rpm, the mixture was removed from the reactor, quench cooled in , ~ ~
~ 20 hexane, dissolved in trichlorobenzene at 130C., precipitated in ~ -: ' .
cold methylethylketone and dried at 95C. and 0.2 mm`mercury absolute pressure overnight. The precipitated product contained 2.3% by weight of NBDA mers and 1.7% by weight of DEF mers. The HLMI of the gross product was 10.8. Thus, cografting is readily achieved with ~BDA and DEF as well as with XMNA and DBM.
:, j: ; :
In preparing the blends of this invention from the above graft copolymers and the polyethylene resin or resins any :~, .
blending equi?ment or technique may be used. As an example only, 1~ all of the blends were prepared in an electrically heated Brabcnder ;~- 30 Plasticorder mixing head using a scroll type mixer under the following conditions: temperature = 350F., rotor speed = 120 rpm . and mixing time = 5 minutes after flux.

`` : - ~4-,.. . . ... . . - ~. ~. ~ . . .

1~83Z9~

Example 18 X~A is reacted with high density polyethylene homo-polymer resin in a twin-screw extruder to give a graft copolymer resin with 1.O weight percent XMNA inCOrpOration and a melt index of 0.8 gm/10 min. The abo,ve graft copolymer is blended in vary-ing amounts with a high density polyethylene homopolymer resin of a melt index of 0.21 gm/10 min. ana a density of 0.96 gm/cc using the procedure described above. The blends as well as the -graft copolymer resin itself and the high density polyethylene ~
. .
,- 10 homopolymer resin itself are tested for adhesion to nylon 6 film using the following procedure. ~ ~ ~
~,, The resultant blends were compression molded into films ~ ' t ~ .
~ approximately 0.006 inch thick at 350F. The films were then ', pressed to the substrate under evaluation in a Pasadena Hydraulic , compression molding press having plates 8" x 8". The samples " to be tested were held at 400F. for 3 minutes at 1000 psig '," followed by quenching in a cold Pasadena Hydraulic Press held ~ at 4000 psig. Slip sheets were used between the blend and the ~- ' ,, substrate in order to provide a tab for subsequent testing of ~`, 20 the composite.
'i:i ;', The resultant composites were tested by cutting into ' .:- .
,' strips of varyi~ widths from 1/16 inch to 1/2 inch. The tab of ~ the test substrate is attached to a fixed support and weights ,, ~
were hung in increments of 50 grams to the tab of the test film forming a 180 peel angle. Attempts were made to maintain an angle of 90 between the peel angle and the composite under test.
; The width of the test strip and the number of weights required to completely separate the composite were recorded.
The T-peel test described above is similar to the test -' 30 described by Dickert et al in Tappi, Vol. 51, No. 6, June, 1968, '~ on page 66A, except that the Tappi test used 30 grams weights and ; ` .
.. , ; ` _ 1 ~_ .
.~ . . . - ~ . . . .. . . . . .

1~83Z9~

a one minute interval was used before the next weight was added.
The point of fzilure in our test is the actual number of weiyhts put on the sa~p'e rather than subtracting one-half of the last weight as described in Dic~ert et al.
The procedure herein described is also related to AST~
D 1876-72 ~-peel strength of adhesives ~ith the following differ-ences:
1. A ~otor driven instrument is used in ASTM D 1876-72 and the test panel is 12 inches long by 6 inches wide. The first 3 inches of length are bent back to form a 90 bend.
2. The separation rate of the bond is 5 inches per minute.
3. Ihe strip width is one inch.
4. Ihe peel strength is determined from the autographic curve for the first 5 inches of peeling after the initial peak.
5. T~e average peeling load in pounds per inch of the specimen width required to separate the adherends is reported.
The results obtained are summarized below:

Graft Copolymer Adhesion to Nylon 6 20ir Blend No. of Weights No. of Weights t.%) (l/16" strip)(l/2" strip) ~:`
O <1 <1 ll ~11 4 ~ll 3 ll O ~l 3 ': ! ~ ~ 1 0 0 < 1 2 As shown by the table, surprisingly, the adhesion of the blends is better than that of either component when tested alone.
This occurs despite the fact that the concentration of anhydride in the blends is reduced by dilution with the ungrafted resin component.
. .
..
:
~ -16-: ,~
.:; ,~..... . . . .... ..
, ~-:~ : , , - . -10~3Z9l Example 19 The graft copolymer resin described in Example 18 is blended at the 3 weight percent level with an ethylene-hexene-l copolymer resin of a melt index of 0.26 gm/10 min. and a density of 0.95 gm/cc. The blend as well as the graft copolymer resin itself and the ethylene-hexene-l copolymer resin itself are tested for adhesion to both nylon 6 film and aluminum foil. The results obtained are summarized below:

Graft abpolymer Alhesion to Nylon 6 Adhesion to Aluminum in Blend No. of~eightsNo. of Weights (wt.%) (1/16" strip)(V16" strip) : O <1 <1 3 >11 6 100 ~1 4 As shown by the above data, alpha-olefin copolymers of ethylene may be used as the blend resin with excellent results.
Furthermore, the adhesion of the blend is better than that of either component when tested alone to various substrates, e.g., nylon and aluminum.
'~:

Example 20 The graft copolymer resin described in Example 18 is blended at the 5 weight percent level with an ethylene-propylene-diene terpolymer resin manufactured by Co~olymer Rubber and - Chemical Corporation and designated Epsyn~5509. The blend as well as the graft copolymer resin itself and the EPDM resin itself '~ are tested for adhesion to nylon 6 film. The results obtained ` are summarized below.
,:-;, Grafted Copolymer Adhesion to Nylon 6 in BlendNo. of '~eights ~ 30 (wt.~)(1/16" strip) ,'. O <1 ` 5 8 100 <1 ,` ~
'' ' ~:

. S .. .

- 1~83291 As shown above, terpolymers of ethylene, an alpha-olefin and a diene may be used as the blend resin with exce~ent results.

., Example 21 The graft copolymer resin described in Example 18 is blended at the 3 weight percent level with a low density poly-ethylene homopolymer resin of a melt index of 3.4 gm/10 min.
and a density of 0.935 gm/cc. The blend as well as the graft copolymer resin itself and the low density polyethylene resin itself are tested for adhesion to both nylon 6 film and aluminum foil. The results obtained are summarized below:

Graft obpolymer Adhesion to Nylon 6 Adhesion to Aluminum in BlendNo. of WeightsNo. of Weights (wt.~) (1/16" strip) (1/16" strip) -O <1 <1 100 <1 4 '~
As shown by the above data, low density homopolymers of ethylene may be used as the blend resin with excellent re-j`; sults. Again, the adhesion of the blend is better than that ;,,~
~` 20 of either component when tested alone to various substrates, . i~
i~ e.g. nylon and aluminum.
, .. . .
i ;~:
Example 22 XMNA together with dibutyl maleate (DBM) are reactedwith an ethylene-butene-l copolymer resin in a twin-screw extruder to give a cografted copolymer resin with 1.4 weight percent X~A
. g~
and 1.1 weight percent DBM incorporation and a melt index of 0.64 gm/10 min. The above graft copolymer is blended at the 3 weight . percent level with an ethylene-hexene-l copolymer resin of a melt index of 0.26 gm/10 min. and a density of 0.95 gm/cc. The blend ~`i` 30 as well as the graft copolymer resin itself and the ethylene-` hexene copolymer resin itself are tested for adhesion to nylon 6 -~ film. The results obtained are summarized below:
. .

: ~ - , .. . .

Graft Co?olymerAdhesion to Nylon 6 in Blend No. of Weights (~t.~) (1/16" strip) 100 <1 As s.:o,m above, alpha-olefin copolymers of ethylene fused rinq acid cografted with unsaturated/carboxylic ~nhydride plus ester monomers may be used as tne graft copolymer component with excellent results.
' ~
Ex--~ple 23 The craft copolymer resin described in Example 1~ is blended at the 5 weight percent level with a high density poly-ethylene homopolymer resin of a melt index of 0.21 gm/10 min.
and a density of 0.96 gm/cc. The blend as well as DuPont Surlyn~
1652 ionomer resin are tested for adhesion to nylon 6 film. As prepared, it required 5 ~-eights to separate a 1/16 inch strip of the ionomer resin fro~ the nylon film and 11 weights to separate a 1/16 inch strio of the graft copolymer blend from the 20 nylon film. If a drop OL water is placed at the point of sepa- -ration of the .est film ænd nylon film, one weight is sufficient to completely separate the ionomer resin film from the nylon film, whereas, 11 weights are required to separate the graft copolymer blend film fro~ the nylon film with or uithout the drop of water.
This shows that the adhesive bond formed between the ionomer resin and nylon is readily affected by moisture, whereas, the adhesive bond formed bet~;een the graft copolymer blends and nylon is not easily affected by moisture.

Example 24 The graft co?olvmer described in Example 18 is blended into a mixture of 30 wei~ht percent of a terpolymer of ethylene, propylene and e,hylidene norbornene and 70 weight percent of a .

:~ -19-.j ..... . .. . . . . . . . .

1(~83Z9l high density polyethylene with a high load melt index of 13 and a density of 0.954. The graft copolymer itself, the mixture of the two polymers, and the graft copolymer blend were tested for adheslon to aluminu~ foil with the followirg results:

Graft Copolymer Adhesion to Aluminum in Blend~DPE-EPDM~o. of ~eights (wt.~) Mixture1/16" strip) O 100 <1 ' .

The results demonstrate that mixtures of ethylene-propylene terpolymer and high density polyethylene can be used as the blend resin with excellent results. Again, the adhesion of the blend is better than that of either component when tested ; alone.
,j .
Example 25 X~NA is reacted with a high density polyethylene homo-.1! polymer resin in a twin-screw extruder to give a graft copolymer resin with 1.0 weight percent incorporation. The above graft copolymer is blended in varying amounts with a polyethylene homopolymer resin whose density is .96+ and melt index is 0.2.
For comparison purposes XMN~ is reacted with a low - ~ density polyethylene homopolymer in a twin-screw extruder to give a graft copolymer with 1.0 wt.% XM~A incorporation. The graft copolymer is blended in varying amounts with the same `IY polyethylene homopolymer described above.

The blends as well as the graft copolymers themselves and the polyethylene homopolymer itself are tested for adhesion ~,;i.~
to nylon 6 films. The results obtained are su~arized below:

, , ~ -20-, ,, ,~
. . .: - , , .

1083Z9l XMNA Graft CopolymerAdhesion to Nylon 6 prepared from HDP~No. o Weights (Wt.% in Blend)(1/16" strip) O <1 100 <1 XMNA Graft CopolymerAdhesion to Nylon 6 10prepared from LDPENo. of Weights (Wt.~ in Blend)(1/16" strip) :' o <1 ".
<1 - 15 <1 <1 :: 100 <1 '~
:
As shown by the table, surprisingly, the blends con-taining the high density polyethylene graft copolymer are adhesive to nylon whereas the blends containing the low density ~ 20 polyethylene graft copolymer are ineffective even though the '$~ grafting monomer and resultant graft incorporation are equivalent.
~ Furthermore, it is surprising that the XMNA graft copolymer pre-;~ pared from high density polyethylene when blended with high density polyethylene has adhesion to nylon that is greater than either component alone, i.e., a synergistic effect is obtained. -These examples clearly indicate that the nature of the graft . i .
copolymer has to be very specific to produce effective adhesive ;
blends. Not only does the anhydride have to be of a very ~ ;~
specific type, i.e., fused ring, but also the polyethylene back~
bone must be high density.

; Exam ~e 26 Dex 000, a commercial polyethylene acrylic acid graft copolymer ha~ng an acrylic acid content of 1.0 wt.~ is ; . . .. .
` ~ blended with a polyethylene homopolymer resin whose density is -~

0.96~ and whose melt index is 0.2 gm/10 min.
,. ~, '':

; .
.

- . . . . . - . . . .. . . .. .

The blend, the blending resin, and the graft copolymer itself are tested for adhesion to nylon 6 film.
For comparison purposes X~NA is reacted with high density polyethylene homopolymer resin in a twin-screw extruder to give a graft copolymer with 1.0 wt.% ~INA incorporation. ~his graft copolymer is blended with the same resin and in the same proportion as the acrylic acid graft copolymer described above.
The results are summarized as follows:

Acrylic Acid GraftAdhesion to Nylon 6 10Copolymer in Blend No. of Weights (wt. %)(1/16" strip) ', O <1 <1 100 <1 XMNA Graft Copolymer Adhesion to Nylon 6 in BlendNo. of Weights (wt. ~)(1/16" strip) O <1 ~11 20 100 <1 These examples show that the acrylic acid copolymer when blended with polyethylene does not have any adhesion to nylon. In comparison, the fused ring anhydride XMNA graft co-- polymer blend shows excellent adhesion to the non-porous nylon surface.
,'.~ ' : ' Example 27 Dexon 1001, a commercial acrylic acid graft copolymer having a melt index of 50 and an acrylic acid graft content of

6 wt.% is blended in varying amounts with a high de~ity poly-ethylene homopolymer resin of a melt index of 0.21 gm/10 min.
and a density of 0.96 gm/cc. The blends as well as the graft ~ copolymer resin itself, and the high density polyethylene homo-; polymer resin itself, are tested for adhesion to nylon 6 film.
The results are summarized below:

. ~:~ .- - ..

^ Adhesion to Nylon Grart Co~olymer in blend No. of weic~llts (wt. ~) (1/1~" strip) 3 <1 <1 <1 <1 100 < 1 As can be seen, the acid graft copolymer blends do not have any adhesion to nylon. In comparison, a qraft of this invention used at levels of 3 and 5 wt.~, when blended in the same manner, gives adhesion to nylon of 11 weiqhts.
:
Ex~m~le 28 X~A is reacted with a high density polyethylene homopolymer in a twin-screw extruder to give a graft copolymer resin ~7ith 1.0 ~J~. % incorporation and whose melt viscosity =
1~5 x 105 poise (nA). The above graft copolymer is blended with -a polyethylene homopolymer resin whose density is .96+ and whose melt shear viscosity is 3.4 x 10 poise (~B) at the 5 wt.% level, `; 20 where nA is the shear viscosity of the graft copolymer and nB is r;'~ the shear viscosity of the blending resin.
;~ For comparison purposes the high density graft copolymer resin described.above is blended with a low molecular weight ~-,~ polyethylene homopolymer whose melt viscosity is 4 x 102 poise t '` ~ (~B) at the 5 wt.~ level. The results obtained are summarized . . . - - i, .
below:
Adhesion to Nylon No. of Weights nA
(1/16" strip) log ~}3 X~ Graft Copolymer I blended with HDPE Homopolymer 11 <2 ~A Graft Copolymer blended with low ~r.~ Polyethylene 0 >2 ~! The low molecular weight polyethylelle docs not sa ti.sfy the specification, log ~B <2, and the resultant blend does not `` sho~ any adhesioI-; ho~everr hi~h molecular wei~ht polyethylene . ~ .:
satisfyinq the specification does exhibit stronq adhesion.
: 23 `' ` ~. ` .. . . .
, - , -,`, . .`- ~ , , ~ , . ,.. ,.. ~ ,. , - ~ .
. . ,; ,. , ~ . .

~083291 ~.xam]c 29 _ __ __ ~ ic anhydride is r~acted ~7ith a high density poly-ethylene ho~nopolymer resin in a twin-scrc.~ extruder to give a graft co2olymer resin tith 2.~ wt.% maleic anhydride incorpor-ation and a hi~n load melt index of 6.9 ym/10 min. The above graft copolymer is blended in varying amounts with a high density polyethylene homopolyrner resin of a melt index of 0.21 gm/10 min.
and a density of 0.96 gm/cc using the procedure described above.
The blends as ~ell as the gra~t copolymer resin itself and the high density polyethylene homopolymer resin itself are tested for adhesion to nylon 6 film using the procedure described above.
Tne results are summarized as follows:

Adhes-ion to Nylon 6 Graft Copolymer inNo.of Weights Blends (wt.~_ (1/16" strip) 3 Cl ; 5 ' 25 <1 20100 <1 This example shows that despite the fact that maleic ' anhydride is grafted to the exact same backbone as is ~ ~A and also blended with the exact same blending resin as in Example 18 for the X~A, the adhesion of blends with maleic anhydride grafted copolymer is extremely poor when compared wi~h those of an X~A graft copolymer. This emphasizes that not all anhydrides are equivalent in producing blends for adhesion to a nylon 6 substrate.
Example 30 The ~`~A gxaft copolymer described in Example 18 is blPnd~d in varying amounts with a polyethylene copolymer of a melt index of 0.26 and a density of 0.953. The b]ends are testcd for adhesion to nylon 6 as describecl ahove. The results are as f~ows:
. 24 :
~dhesion to Mylon 6 Gra~ t Copolymer inNo. of WeicJh-t~
~l~nds (wt.~) (l/16" stripl _ 3 >ll lS 3 Exam?le 31 The rnaleic anhydride qraft copolymer described in Example 29 is blended in varying amounts with a polyethylene copolymer of a melt index of 0.26 and a density of 0.953. The blends are tested for adhesion to nylon 6 as described above and with ,he following results:

Adhesion to Nylon 6 -Graft Copolymer inNo. of Weights Blends (wt.%) (1/16" strip) ., . - :

~1 .,', : . .
q 20 At equal weight percent of graft copolymer ~7hen com~
pared to the X~A grafted copolymer blends of Example 30, it can be seen that the adhesion of the latter is far superior to the blends of the maleic anhydride grafted copolymers. In ~-fact, the adhesion to nyIon of the blends of this Example 31 is ;~ poor. This emphasizes again that fused ring anhydride grafts ~; -are superior and not all anhydride-grafted copolymers are equiv-alent in adhesion to a typical substrate, namely nylon.

All parts and percentages herein are by weight.

A summarizing list of the abbreviations used herein to identiIy chemical ingredients is as follows:
. ~ .
BOD~ - bicyclo(2.2.2)oct-5-ene-2,3-dicarboxylic acid anhydricle DB.I - dibutyl maleate DEF - di~thyl fumarate - EPD`I - ethylene-propylene diene terpolymer :

~083Z91 , , .

4-MTHPR - 4-methylcyclohex-4-ene-1,2-dicarboxylic acid anh~dride HDPE - high density polyethylene LDPE - low density polyethylene MA - maleic anhydride NBDA - bicyclo(2.2.1)hept-5-ene-2,3-dicarboxylic acid anhydride ODCB - o-dichlorobenzene .
: TBHP - t-butyl hydroperoxide THPA - tetrahydrophthalic anhydride ~ X~A - x-methylbicyclo(2.2.1)hept-5-ene-2,3-: dicarboxylic acid anhydride ` Having described our invention as related to the em-. bodiments 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.
',~';, .
, .
, . .
s ~
J

`!; , `'',` ~ ~ ' '. ' "
: . : - - , .

~ ' ' , ' .
~ .
"` .
'i;
" ::
:
' .' .

,:".'.,~ ''' ":,' '' `, ' .,. ' .' " ' - ' ' . ''' ' ~

Claims (35)

WE CLAIM:

1. A modified polyolefin blend having improved adhesion to various substrates and consisting essentially of:
(A) about 0.1-95 parts by weight in said blend of a graft copolymer of about 70-99.999 wt.% of a high density polyethylene backbone grafted with about 30-0.001 wt.% of at least one compound containing at least one member of the group con-sisting of unsaturated acyclic, carbocyclic, heterocyclic, and polycyclic moieties which are fused to at least one carboxylic acid anhydride-containing ring and (B) about 99.9-5 parts by weight of a polyethylene resin selected from the class consisting of homo-polymers of ethylene, copolymers of ethylene and alpha-olefin, terpolymers of ethylene, alpha-olefin and diene and mixtures of these polyethylene resins.

2. The blend of claim 1 wherein said (B) resin comprises an ethylene homopolymer.

3. The blend of claim 1 wherein said (B) resin comprises a copolymer of ethylene and an alpha-olefin.

4. The blend of claim 1 wherein said (B) resin comprises a terpolymer of ethylene, alpha-olefin and diene.

5. The blend of claim 2 wherein said (B) comprises polyethylene of a density of from about 0.910-0 965.

6. The blend of claim 1 wherein said (B) comprises a linear copolymer of at least 60 wt.% of ethylene and up to 40 wt.% of an alpha-olefin containing 4-6 carbon atoms for a total of 100 wt.%.

7. The blend of claim 1 wherein said (B) comprises a terpolymer of ethylene, propylene and up to 5 wt.% for a total of 100 wt.% of a member of the group consisting of cyclic and acyclic aliphatic dienes and mixtures thereof.

8. The blend of claim 1 wherein said (B) comprises a mixture of ethylene polymers, ethylene-alpha-olefin copolymers and ethylene-propylene-diene terpolymers.

9. The blend of claim 1 wherein said (B) comprises a mixture of ethylene polymers and ethylene-alpha-olefin copolymers.

10. The blend of claim 1 wherein said graft copolymer of (A) comprises a high density polyethylene polymer and 4-methyl-cyclohex-4-ene-1,2-dicarboxylic acid anhydride.

11. The blend of claim 1 wherein said (B) comprises a mixture of ethylene polymers and ethylene-propylene-diene ter-polymers.

12. The blend of claim 1 wherein said graft copolymer of (A) comprises a high density polyethylene polymer and at least one monomer comprising tetrahydrophthalic anhydride.

13. The blend of claim 1 wherein said carboxylic acid anhydride of (A) consists essentially of x-methyl bicyclo(2.2.1) hept-5-ene-2,3-dicarboxylic acid anhydride.

14. The blend of claim 1 wherein said (B) consists essentially of an ethylene-hexene-1 copolymer resin of a melt index of about 0.26 gm/10 min. and a density of about 0.96 gm/cc.

15. The blend of claim 1 wherein said (B) consists essentially of an ethylene-propylene-diene terpolymer resin.

16. The blend of claim 1 wherein said (B) consists essentially of a low density polyethylene homopolymer resin of a melt index of about 3.4 gm/10 min. and a density of about 0.935 gm/cc.

17. The blend of claim 1 wherein said polyethylene backbone consists essentially of a high density polyethylene having a density of about 0.930-0.970 gm/cc.

18. The blend of claim 1 wherein said compound is present in an amount of about 0.001-5 wt.% and said high density polyethylene backbone in an amount of about 99.999-95 wt.%.

19. The blend of claim 1 wherein said moiety is carbocyclic.

20. The blend of claim l wherein said compound contains up to about 35 carbon atoms.

21. The blend of claim 1 wherein said graft copolymer contains one or more of said anhydrides.

22. The blend of claim 1 wherein said polyethylene of (B) is selected to satisfy the equation:
log <2, where nA = the shear viscosity of graft copolymer nB = the shear viscosity of said polyethylene.

23. The blend of claim l wherein said carboxylic acid anhydride of (A) consists essentially of an acid anhydride taken from the group consisting of 4-methylcyclohex-4-ene-1,2-dicarboxylic acid anhydride, bicyclo(2.2.2)oct-5-ene-2,3-dicarboxylic acid anhydride, and bicyclo(2.2.1)hept-5-ene-2,3-dicarboxylic acid anhydride.

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

25. The composite structure of claim 24 wherein said substrate comprises a member of the class consisting of polar polymers, solid metals, glass, paper, wood and cellophane.

26. The composite structure of claim 24 wherein said substrate is taken from the group consisting of nylon and aluminum.

27. The composite structure comprising:
(A) a solid substrate, and adhered thereto (B) a modified polyolefin blend according to claim 2, claim 3 or claim 4.

28. The composite structure comprising:
(A) a solid substrate, and adhered thereto (B) a modified polyolefin blend according to claim 5, claim 6 or claim 7.

29. The composite structure comprising:
(A) a solid substrate, and adhered thereto (B) a modified polyolefin blend according to claim 8, claim 9 or claim 10.

30. The composite structure comprising:
(A) a solid substrate, and adhered thereto (B) a modified polyolefin blend according to claim 11, claim 12 or claim 13.

31. The composite structure comprising:
(A) a solid substrate, and adhered thereto (B) a modified polyolefin blend according to claim 14, claim 15 or claim 16.

32. The composite structure comprising:
(A) a solid substrate, and adhered thereto (B) a modified polyolefin blend according to claim 17, claim 18 or claim 19.

33. The composite structure comprising:
(A) a solid substrate, and adhered thereto (B) a modified polyolefin blend according to claim 20, claim 21 or claim 22.

34. The composite structure comprising:
(A) a solid substrate, and adhered thereto (B) a modified polyolefin blend according to claim 23.

35. The blend of claim 1 wherein said (A) comprises a high density copolymer of at least 60 wt.% ethylene and up to 40 wt.% of an alpha-olefin containing from 4 to 6 carbon atoms.