CA2137283A1 - Paintable polyethylenes - Google Patents

Abstract

Paintable, thermoplastic polymer blends are prepared from (A) at least about 50 weight percent polyethylene, for example, high density polyethylene (HDPE), grafted with at least about 0.01 weight percent of an unsaturated organic compound, for example, maleic anhydride, and (B) a thermoplastic polymer containing polar groups, for example, a polyurethane or a polyester. Optionally, the grafted polyethylene of (A) can be diluted with an ungrated polyethylene, for example, ungrafted HDPE. These blends can be molded into various structural components, for example, automobile parts, and can be painted without the use of either a primer or a preliminary surface treatment, for example, chemical etching. The polyethylene blends also demonstrate excellent adhesion to various rigid polyurethane foams.

Description

W O ~3/25617 ~ 1 3 7 2 8 3 PCT/US93/05363 ,~ ' pAINTABI.E POLYE~ I,.ENES

s This invention relates to functionalized polyethylenes. In one aspect, the invention relates to polyethylenes grafted with an un~saturated organic compound containing at least one double bond and at least one -~
functional acid group, for example, maleic anhydride, while in another aspect, the invention relates to the high compatibility of these functionalized polyethylenes with various thermoplastic polymers containing a polar group. In one embodiment, the invention relates to articles molded from blends of functionalized polyethylenes and such polymers that can be painted without a surface pretreatment or a special primer while in another embodiment, the invention relates to laminates of 15 functionalized polyethylenes and certain polyurethane foams that demonstrate near perfect adhesion to one another.

Because of their light weight, durability, low cost and other desirable properties, thermoplastic polyolefins (TPO's~ have steadily grown in~use as a material of construction for a large array of consumer goods. ~ Por example, the automotive industry uses these materials in a `~-vari;ety o~f interior and exterior parts, while household appliance ~`;
manufacturers employ TPO's in everything from support structures to decorative facia. s-~
2s While TPO's have many desirable properties, they also have certain ~`
undesirable properties not the least of which is their reluctance to ~`
accept a paint or decorative print. TPO's are, by definition, hydrocarbon `~
polymers, typicalIy a polyethylene, polypro~ylene or an ethylene-propylene .j~
; ~ ~ rubber, and~as such, are nonpolar. Most paints are polar, and thus -`-, .
require a surface with some degree of polarity before they can adhere to it with any degree of desirable fastness. This problem has been ~ .
addressed, with varying degrees of success, in a number of different ways.

One relatively common solution is to apply a primer to the TPO.
Primers are typically compositions containing a halogenated polyolefin and an aromatic solvent, for example, a chlorinated polypropylene and toluene. ~;~
Wh1le primers are generally recognized as effective, they are expensive ~. ~

' , :
:

~ 1 37~ 3 -~

and their application is an extra step in the finishing of the TPO
article.
''.'~
Another method of enhancing the paintability of a TPO surface is to 5 subject the surface to a physical or chemical etching, or irradiating the surface with a plasma. While generally effective, these methods are more complex in nature than the application of a primer, and thus more difficult to control in terms of quality and consistency from part to part. In addition, these techniques are generally more expensive than the 10 simple application of a primer.

Yet another technlque~ and one that continues to grow in use, is to modify the physical and/or chemical properties of the TPO either by blending it with other thermoplastic polymers, or by incorporating into it s one or more polar groups, or both. For example, USP 4,~46,896 to Mitsuno et al. teaches a paintable~TPO comprising 20-80 weight percent polypropylene; 5- 8 weight percent of an ethylene copolymer consisting of ethylene, an ester unit of either alkyl acrylate or methacrylate, and an --unsaturated~dlcarboxylic acid anhydride; and 5-70 weight percent ethylene- -~
propyl~ene rubber. ~USP 4,888,391 to~Domine et al. teaches a paintable po~lyoléfin~ com2osition~compri;sing a blend of a polyoléfin as the continuous phasè with an ethylene/acrylate/acrylic acid terpolymer as the dlscontlnuous phase. Yet another teaching is USP 4,~45,005 to Aleckner, `-~ Jr. et~al. which teaches paintable TPO's comprising 2-25 weight percent of `~;
- 2s~ a copolymer of an ethylenically unsaturated carboxylic acid and ethylene;
3-50~weight~perc-nt of an ethylene-alpha-olefin copolymer; optionally a `~
crys~tall~ne~homopo1ymer or copolymer of propylene; 5-50 weight percent of an~inorganic flller~; and 10-3S welght percent of a polyethylene or a ~ `
cQpolymer of~eehylene and an alpha-olefin. These and other modified TPO ~`
compositions~all demonstrate some degree of efficacy, but none are ~completely satisfactory with respect to such;considerations as ease of `~
formulation and cost. ~`

, ~ 2- ~
'~ ~
. ~, .
'~ .

W 0 93/2S617 ~ 1 3 7 2 ~ 3 j PCT/US93/05363 1' ., .,. '' ';;~;

According to this invention, a paintable thermoplastic composition ~- comprises:

A. At least about 50 weight percent polyethylene grafted with at least about O.Ol weight percent, based on the weight of the ~ ;
polyethylene, of an unsaturated organic compound containing at least one double bond and at least one functional acid group; and ~
,,-:
B. At least one thermoplastic polymer containing polar groups. ` :

Preferably, the polyethylene is a high density polyethylene, and it ... `
5 comprises at least a~bout 80 weight percent of the composition. The .i`~
thermoplastic polymer is preferably a nylon or polyurethane. In one -embodiment of this invention, the compoaitions are molded into various cles,~for~ex1mp1e,;;automQb11e~;~parts, wh11e in another embodiment, the i~
gratéd~po ~ 1ene~(g-PE)~is~1am1nated to a polyurethane foam. In yet another~embodlment,~the~ g-PE~ is ~1ended~with and demonstrates excellent adhèsion~to other~materials, such as~wood~,~metal and latex paints. The paintable~thermaplastic compositions of~this invention can receive and `hold~p11nt without~the~use of a primer or preparatory surface treatment, as~can _ ny ot th- g-PE/oCher~m1~eria1 b1enis.

Any;ethylene polymer or`copolymer that can be grafted with an;a`~-u~noaturated organic~compound~containing at least one doubie~bond and a~ `~Y~
-; léast~one funct;iona1 ac1d group can be~used in ~his invention. Ethylene polym~ers and~copolymers fall~ into two broad categories, those prepared ^:
with a~free radical initiator at high temperature and high pressure, and ~i~ those prepared with~a coordination catalyst at high temperature andi~
relatively~ iow pressure. The formeriare gènerally known as low density -polyethylenes:(LDPE) and are characteri~ed ~y branched chains of polymerized-m~onomer units pendant from the polymer backbone. L~PE polymers generally have a density between Q.9lO and 0.935 g/cc. - ;

~3~

W O 93~25617 ~ t 3 7 2 8 ~ ~ P~r/US93/05363 Ethylene polymers and copolymers prepared by the use of a coordination catalyst, such as a Ziegler or Phillips catalyst, are generally known as linear polymers because of the substantial absence of branch chains of polymerized monomer units pendant fronl the backbone.
High density polyethylene (HDPE), generally having a density of 0.941 to 0.965 g/cc, is typically a homopolymer of ethylene, and it contains relatively few side branch chains relative to the various linear copolymers of ethyle~e and a~ olefin. HDPE is well known, commercially available in various grades, and is useful in this invention.

Linear copoly~ers of ethylene and at least one alpha-olefin of 3 to :
12 carbon atoms, preferably of 4 to 8 carbon atoms, are also well known, -~
commercially available and useful in this invention. As is well known in the art, the density of a linear ethylene/alpha-olefin copolymer is a 1S function of both the length of the alpha-olefin and the amount of such ~ -monomer in the copolymer relative to the amount of ethylene, the gre?ter ~
the length of the alpha-olefin and the greater the amount of alpha-olefin `:
present, ~the~lower the density of the copolymer. Linear low density `~
polyethylene (LLDPE) is typically a copolymer of ethylene and an alpha- .~-~olefin~of~3 to 12 carbon atoms, preferably 4 to 8 carbon atoms (for -`
example,~ l-butene, l-octene, etc.), that has sufficient alpha-olefin content to reduce the density of the copolymer to that of LDPE. When the .:~
copolymer contains even more alpha-olefin, the density will drop below ~ -- ~ about 0.9l g/cc and these copolymers are known as ultra low density : ~, - , .
- 25~ polyethylene (ULDPE) or very low density polyethylene (VLDPE). The densities~of these linear polymers generally range from 0.87 to 0.91 g/cc.
.:- -- ~

Both the materials made by the free radical catalysts and the ` -coordination catalysts~are well known in the art, as are their methods of :
preparation. Relevant discussions of both these materials and their .~-methods of preparation are found in USP 4,950,541 and the patents to which it refers, alll of which are incorporated herein by reference. HDPE is the `
preferred polyethylene for use in grafting in this invention. Preferably, .
the HDPE for grafting has a melt index of about 10-25 g/10 min, and a :`
density of about 0.95 - 0.965 g~cm3. ~ --; `.:
-4- -~

W O 93/25617 ~ 1 3 7 2 ~ 3 ` P ~ ~USg3/05363 Any unsaturated organic compound containing at least one double bond and at least one functional acid group that will graft to a polyethylene polymer or copolymer as described above can be used in the practice of this invention. Preferably, the compound to be grafted onto the polymeric s chain contains a double bond conjugated with the double bond of an acyl group, and preferably the compound has a moderate tendency to polymerize to yield polymers of relatively high molecular weight and which readily - undergo chain transfer reactions. Typical of such compounds are the acids - ~
and anhydrides, if any, of maleic, fumaric, acrylic, methacrylic, ~ :
10 itaconic, crotonic, alpha-methyl crotonic, cinnamic. Maleic anhydride is `~
the preferred unsaturated organic compound containing at least one double :
bond and at least one functional acid group.

The unsaturated organic compound content of the grafted polymer is ~
at least about 0.01 weight percent, and preferably at least about 0.05 ;
weight percent. The maximum amount of unsaturated organic compound -'~
content can vary to convenience, but typically it does not exceed about 5 ~ weight percent, preferably it does not exceed about 2 wei;ght percent, and ~-~
i~ ~ more preferably it does not exceed about 1 weight percent.
- ~
The unsaturated organlc compound can be grafted to the polymer by ``
any known technique, such as those taught in USP 3,236,917 which is . .~ , , incorporated~herein by reference. For example, the polymer is introduced into a two-roll mixer and mixed at a temperature of 60 C until a 2s relatively homogeneous mixture is obtained. A free radical initiator, ~;
such as benzoyl peroxide, is added along with the unsaturated compound and the components are mixed at 30 C until the grafting is completed.

An alternative and preferred method of grafting is taught in USP
,950,541, the disclosure of which is incorporated herein by reference, by ;using a twin-screw devolatilizing extruder as the mixing apparatus. The polymer and unsaturated organic compound are mixed and reacted within the extruder at temperatures at which the reactants are molten in the presence of a free radical initiator. Preferably, the unsaturated organic compound lS injected into a zone maintained under pressure within the extruder.

~1 372~3 The ethylene interpolymer used in this invention contains a plurality (i.e. more than one) of pendant o~ygen-containing groups. As here used, ethylene interpolymer means a polymer made from at least dthylene monomer and a monomer containing an o~ygen-containing group, the latter monomer including carbon monoxide. Optionally, these interpolymers may also include units derived ftom one or more other monomers containing ~,B~thyl~nic unsaturation. ~.g propvl~ne, 1-he~ne, l~ctane, butadiene, and the like. Typical of the monomers containing an o~ygen-containing group that can be used to make the --interpolymers used in this invention are acrylic acid, methacrylic acid, itaconic acid, crotonic acid, cY-methyl crotonic acid, cinnamic acid, carbon mono~ide, and the like. Representative of these interpolymers are EAA9 EMA, ECO, EPCO and EVA.
",,~;,, ~ ,~
lhe ethylene interpolymers used in this invention are sufficiently compatible with the grafted - -polyethylene (g-PE) such that the blend of the two does not separate either during or subse4uent to mixing. --~
The copolymer of ethylene and acrylic acid (EAA) manufactured and sold by The Dow Chernical Company ~-~
~- ~ und the trademark PRlMACOR is a preferred ethylene interpolymer for use in this inven~ion. . ~ -The molecular weights of these interpolymers can vary widely but for compression molding, ~;
typica11y the interpoiymers used i~ this embodiment have a melt inde~ (I., measured according to AST~ D-1238, condition 190 C/2.16 kg) between about 0.01 and about 3,000, preferably between about 0.1 and . ":~
about 300 g/~10 min. For inJection molding, the melt inde~c is typically between about 0.05 and about 1300, ~ .
preferably between about 0.5 and about 100 g/rnin.

The~g-PE comprises a~ least about 45 wt %, preferably at least about 5~ wt % and more preferably ac least about ~0 wt %, of the g-PElethylene interpolymer blend. Preferably only one interpolymer is blended with the g-PE, although blends of two or moro compatible interpolymers and the g-PE can be ~;
prepued if desired. Similarly, usually only ono g-PE is blended with tho interpolymer, although blends of two or more oompatible g-PE can be prepared if desired. Likewise, blends of two or mo~e g-PE and ~wo ~:~
or more inte~polymers can also be prepared as long as each component is compatible with the other compone~ts in terms of stability during processing and after molding.
~ ~' AMENOEO SHEE~

In certain embodiments of this invention~ the thermoplastic composition comprises one or more ~ ~
other cornponents to impart one or more desirable features to an article molded from the composition. For ~ `
..~ ,~ , d~ample, inert fillers such as talc, fiberglass, carbon fibers, etc., can be added to the composition to impart `' ~:
buL~c and/or physical strength to the rnolded compositiorl. Likewise, pigments, dyes, etc., can be added for `
color; an~io~idants, biocides, atc. for long-terrn stability; plasticizers, lubricants, etc. as processing aids; and the like. `.

. .. _. .-j :"
The g-PE and the ethylene interpolymer are mixad with one another in any conventional manner that ensures the creation of a relatively homogeneous blend. If the blend is molded into a linished article b,v 0 a~trusion, the g-PE and athylene interpolymer are typically introduced into the e~truder separately and mi~ed within it prior to e~trusio~. If the blend is molded by a compression or injection technique, then the two components are first well mi~ed by any conventional means, e.g., roller mill, agitator. etc., and then introduced as a homogeneous rnass into the mold. While the surfaces of the mold or die heads can be constructed or any material (usually stainless steel), preferably ~hese surfaces are constructed of or coated ; .
lS with a polyester or polyester film such as Myiar~ (rnanufactured by the E. I. Du Pont de ~emours Company)i Articles shaped under relatively low shear conditions, e.g., by compression molding, .
démonstratè~better paint adhesion than articles shaped under relatively high shear conditions, e.g., injection - .
molding. However, the compositions of t~us invention are particularly well adapted for produci~g paintable ~ ~ `
, inJection-molded rticles, such as automobile parts.

In~ anothar embodiment of this invention, the graifted polyethylene is "let-down" or diluted with virgini polyethyle~e or another g-PE prior to its use as a blend component or adh~sive. For e~ample, after the g-PE has been prepared as described in USP 4,950,541, it is then baclc-blended in an e:ctruder with Vlrgini polyethylene to a predeter nined diluOon. Let-down or dilution laitios will vary with the ultimiate Z5 applicadon~of the g-PE, but wcight rados between 1:10 a~id 10:1 are typical. ~-lhie following e~camples are illustrative of certain specific embodiments of this in~entionsi. All parts iand percentages are by weight unless otherwise noted.
. ~
AMENDED SHE~T ~:

~ .

~137283 SPECIFIC EMBODIMENTS :

Ex. 1~ and Controls C-l to C-7: Automotive Paint Adhesion Tasts -~
S ;'' Sarnr)le Pre~aration In all samples the grafted polyethylene was a high density polyethylene (HDPE! grafted with maleic anhydride (expressed as HDG) according to the procedure described in USP 4,950,541. In all samples the ''.!- `
ethylene interpolymer was Prirnacor~, either 1410 or 5980 (grades of EAA made by The Dow Chemical Company with an acrylic acid content of about 9.~ wt ~o and about 20 wt %, respectivelv).
The grafted polyethylene and ethylene interpolymer were fed into a Werner and Pfleiderer ZKS-30 twm-jcrew e~truder operated to about 210 C. The blends were made in one pass.
All samples were injection-molded using a 50 ton Negri-Bossi Injection ~older operated with a barrel temperature between 200 and 250 C, a barrel pressure of ~0 bars, cooling mold temperature of 85 F, lS and a residence time in the cooling mold of about l~ seconds. The samples were forraed into 6~ ,Y 6" .Y
3/4~ plaques.

Pain~ Adhesion Test P~otocols After the samples were washed, they were painted with a two-component polyurethane paint system ZO combining white paint iand isocyanate (e.g., 317LE19~47-SRA white paint iand Durethane~ LE 800 series sold by~ PPG Industnes, Inc.). Each plaquè W8 given a single top coat (no adhesion promoter or primer was applied), and baked for 40 mmutes at 180 F.
Initial patnt ~ion was detemuned using tho crosshatch and tape peel test of ASTM D3359-8 and the dime scrapo test of GM-9506-P. If these tests were successfully passed, then the samples were subjected to immersion in a water bath of 1~0,F accotding to GM4~66-P. Each ~sample was then inspected for blisters and wriIIkles. If this test was passed, then tho samplos wero subjected to a second series of the crosshatch llut tapo peol and timo sc~apo tests. Tho results of theso tosts aro summadzcd in tho Tablo 1.

AMENDED SHEET
.:

~137283 1 . `
, .....
g ` ~
, ."

TABLE 1 ' .`
Summary of Automo~ive Pa~nt Adhesio Tests for Samples Made bv Iniection Moldin ;~' . ~. , .
. , .:
E~amDle/ControlBlend Com~osition of Plaque ;~;:
Paintabilitv `'~' HDG;EA:A 1410= 1/1 4 E~ 1 with i % talc i 3 Ex. #1 with 10% talc 4 -~
4 HDG/EAA 1410=3/2 l E.~. #4 with 10% talc ~ - -6 HDG/E.~A 5980=9/1 4 :
C-1 HDPE 25055/EAA 1410= 1/1 3 ,; ' .
C-2 H~PE 25055/EAA 1410=7/3 0 .~ -~0 C-3 HDPE 25055/EAA 1410=9/1 0 C-4 HDPE 25055/HDG=1/1 0 - .: ~:

C~ HDG 0 `
C-~ EAA 1410 4~ ~ ~

Sample pla4ue shriveled. . .
: .
~ :

end of Svmbols Used in Tabl~ I
35 ~
HDG ~ High density polyethylene:(de~sity of 0.955 g/crn', MI of 25 g/10 min) graffed with about 1.5 wt ~ maleic anhydride; the :- ~ : HDG had a MI o~2.5 g/10 min.
~ : EAA 1410 : PrimacoP 1410 (MI of about 300 g/10 mi Talc ~ Micronlff 1000 by PSzer ~ -EAA 5980 PrimacoP 5980 (MI of about 300 g/10 min).
:
EDPE ~25053 `! I ~ ' laigh de~ i polyotkylene havi~g a density of ~0.955 g/cm3 alld a - MI of 25 g/10 min.

~`~ jO ~

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

h l 3 7 2 8 3 , ' Results and Conclusions In Table 1, column 1 reports the E.~tample and Control rlumber tor ~ach sample listed. Column 2 . `
reports the composition of each sample plaque, and Table 2 is a legend for the abbreviatiorls used in Table ~- .
1. Tha ratio tollowing the blend composition description, e.g. the l/l following HDG/EAA of E~ample 1, is the weight ratio of one comporlent to the other component. In E~ample l, half the cornposition by weight was HDG, and half was Prirnacor 1410. Tn Examples ~, 3 and j, the weight percent of talc was based on the total weight of the composition. i.e. in Example 2 the 1/1 blend of HDGIE~ 1410 constituted 95 wt %
of the composition and the talc the remaining S wt %.
Colurnn 4 reports the test results. In this column:
"' ' ~4" means that the painted plaque passed the crosshatch arld dime scrape tests in both the initial test and after the water immersion ~est:

. , ,:;
~3" mealls that the paint~d plaque passed both initial tests but failed either the crosshatch or dime scrape test aher the water immersion tes~

'2" means that the painted plaque passed both initial tests but failed both the cross hatch and dime scrape tests after the water immersion test;
~, "1- means that the painted plaque failed one of the initial crosshatch or dime scrape tests;
and ~;
~0~ means that the painted plaque failed both ir~itial tests.
. j, j ~ ! / ~ , .

Molding conditions directly influenco tho surface properties and thus the paintability of plaques.
~jection molding equiprnent, after meltin~ t'ho pollets, cool the moldings from the &ee surface to tho bulk.
In atdition, the shear ratio for injecdon molding is about 2000-5000/reciprocal seconds. The result of this thesmal and mechal~ical history is that the surface of injection molded articles are diffiwlt to paint wjthout a ~ -~
: .
`'`,:~
AMcl~JDE3 Si !E-~T

11 , , prior surface trea~ment, a.g. application of a primer or surface modification by chemical or mechanical ,:
etching. This is demonstrated by Controls C-l through C-7. Only Control C-7, a plaque made from 100 ;~
percent athylene acrylic acid copolymer, demonstrated near pertect adhesion, but the structural integrity of the plaque is unacceptable as demonstrated by the fact that the sample shriveled in the paint drying oven. :
Those plaques demonstrating good structural integrity, i.e. those contain~ng a high proportion of HDPE, even HDG (C~, demonstrated poor paint a&esion. ~
In contrast, the examples of this invention (Ex. I-o) demonstrate near perfect paint adhesion, with ~ ' and without a filler. As a consequence, articles injection mold~d from these composisions damonstrata both good structural integnty and pai~tability.
~0 Although the invention has been described in detail b,v the preceding axamples, such detail is for the purpose of illustration only and i9 not to be construed as a lirnitation upon the invention. Many variations can be madF upon the preceding e~amples without departing from the spirit and scope of the following claims.

, - ;":

f I "

~ ;'"' ' '"`~' ', ' ' ~.~'.' ' WO93/25617 PZZCI'/US93/05363 i~
~137283 Z~`

TABLE IB (Con~inued) ~
, .,, ~
SUMMARY OF AUTOMOTIVE PAINT ADHESION TESTS
FOR ~AMPLES MADE BY COMPRESSIOZN M~Zl DINZlG
Oven ~ ~
Ex./ Temp . -Control Composi~on of Plaque Pain~ tF~Z Result ....
32 HDG.02 250F t121.1 C) 250(121.1 C) 4 33 HDPEl~Z21HDC;.01=2.5n.5 250F (121.1 C) 250 (121.1 C) 4 34 HDPE10062/HDZG.01=3.3/6.6 250F (121.1 C) 250 (121.1 C) 4 HDPE10062/HD~.01=5/5 250F (121.1 C) 250 (121.1 C) 4 36 HDPE10062/HDG.01=6.6/3.3 250F (121 1 C) 250 (121.1 C) 4 37 HDPE10062/HDG.01=7.5/2.5 250F ~121.1 C) 250 (121.1 C) 4 38 HDPE10062/LLDPE.g.MAH(LLG)=5/5 250F (121.1 C) 250 (121.1 C) 4 39 LLG/CPA-EAA=9/1 250F (121.1 C) 250 tl21.1 C) 4 HDG.OI/PZ1410=812 180F (82.2 C) 220 (104.4 C) 3 41 HDG.01/Dow1ex~Zl2047=~ 4 180F (82.2 C) 220 (104 4 C) - 3 42 HDG.011930(Fiberglass)~ll 250F (121.1 C) 250 (121.1 C) 3 : :
C-28 ~ HDP1~1006VP141Z~ &t2 180F (82.2 C) 220 (104~4 C) 2 ~ ~ 25 C-29 HDPEtCP~UExxel~7/2/1 250F (121.1 C) 250 (121.1 C) 2 ;- C-30 HDG.01t93B~E;iberglass)=Z9/1 250F (121.1 C) 250 (121.1 C) 1 C-31 HDPE/P141&8t2 250F (121.1 C) 250(121.1 C) I
C-32 ~HDZPEl0062/polyes~ .5/.5 250F (121.1 C) 250 (121.1 C) G33 ;~HDPE10062/polyesZle~9/l 250F (121.1 C) 250 (121.1 C) ~o C-34 HDG.Ol~eflon) 250F (121.1 C) 250 (121.1 C) 0 ~ -.. ..
.
C-35 HDPEliZD06l2 ~ 250F (121.1 C) 250 (121.1 C) 0 C-36 l~PE1006~19(Fberglass)=9/1 250F (121.1 C) 250 (121.1 C) 0 C-37 HDZPEl0062/930(Flberglassk9/l 250F(121.1 C) 250(121~.1 C) O ~ i ` :
C-38 ~ZPEl0062.~l3Bl~tblerglass,~9/1 250F(121.1 C) 250 (121.1 C~Z o Z : ~ i ' li ! : Z ~ Z ' I j ~Z
C-39 HDPE1~93XZ~Fitlerglass)dl 250F (121.1 C) 25~`1 (i21.1 C) 0 C4a HDPE100521DER667Z~.5/.5 250F (121.1 C) 2S0 (121.1 C) 0 - C-41 HDZPEl0062JDER667ll Z9ll 250F (121.1 C) 250 (121.1 C) 0 ~ ;~

. .
~o C42 HDPE25055 250F (121.1 C) 250 (121.1 C) 0 ~- ~

:~ - 12-SUBSTITUTE SHEET ` -wo g3~25617 ~ 2, 8 ~ PCI`/US93/05. ~63 TABLE lC
I E(,END F()R C()MPOSITI()N C~FTABLI-~ IA ANP IB .;

s HDPE: HighDensily Polyethylene MAH: Malcic Anhydnde MI: Mell Index ' : .
PE: Polyethylene (v=2,5) Yeloci~y reading of injection molding, for Lwo differenl molding conditions, for exarnplc, 2 and 5, respeclively .-(v=0.2- 1.6) Velocily reading of injeclion molding for many differenl condi~ions arc from 0.2 1o 1.6 (mold 100) Molding lemperalure in injection molding is 100 F (37.8 C) ~ :
15 ~mel~430) Melling lemperature in injec~ion molding is 430 F (221.1 C) (Mylar) Mylar film installed on steel molding surfaces 919: Flbcrglass 919 by CertainTecd : ;
930: Flberglass 930 by CertainTeed ~
20 93B: Fiberglass 93B by CertainTeed . .
93X: . Fiberglass 93X by CertainTced -~AITANE~E94230: Ultr~ Low Density Polyethylene manufactured by The Dow :~ ~ Chemical Company - ~

- 25 CPA: Crystalline Polyamide ~ `
DER667: Dow epoxy resin 66 EAA:~ Copolymer of ethylene and acrylic acid EAAG: Ethylene/ac~ylic acid copolymer having 10 percent acid and a mell index of 2 which was grafted with 1 percent MAH
30 EC0: ` ethylenecarbonmonoxidecopolymer(weight lOpercentmono~
:: oxide) '-Exxe10r Exxelor VA 1830 ethylene/propylene copolymer grafted with and sold by Exxon , 35 HDG: HDPE grafted with MAH

: , . .:

SUBSTITUTE SHEET ~ ~

WO 93/25617 ~ 1 3 7~2 8:~ PCI~US93/05363 ~ ~
, . ' ., .

~ . .
TABLE IC (Corltinued) ~ -LEC.ENl) F(~R COMP081TIC)N ()FTABlE~S IA AND I

s HDG OI HDPE 10062 which was graftcd with abou~ 1 5 weight percen MAH; Ihe graf~ed product had a Ml of about lgllO min HDG 02: HDPE 25355 grafted with aboul 1.5 weight percent MAH; the grafted produc~ had a Ml of abou~ 2.5g/10 min - HDG 04: Ethylene/l-propene copolymer having a Ml of abou~ 25 g/10 min o and ~ densily of aboul 0 955 g/cm3 which was ~raf~ed with about 1 5 weight percent MAH; li-e ~raftcd product had a Ml of about 2 5 gllO min ~DPE 25355 Ethylenc/l-octene copolymer llaving a Mi of about 2S gllO min and a density of about 0 955 g/crn3 -~
HDPE 10062: PE homopolymer havillg a Ml of about lOg/10 min and a dcnsity of about 0 962 glcm3 Dowlex~ 2047: Ethylene/l~ctene copolyrner made by Ihe Dow Chemical Company having a MI of about 2.3gllO min and a density of aboutO.917 g/cm3 LLG: Dowlex~ 2047 ~rafted with about Ipercent by weight MAH
- Nylon: Capron 8207 by Allied-Sional `~

P1410: Primacor~ 1410 is an ethylene/~rylic acid copolymer m~de by ;~
The Dow Chemical Company having a Ml of about 0.5 g/10 min ;~
and abou~ 10 weight percenl acrylic acid content ~ ;
P5980: Primacor~9 5980 is an ethylene/acrylic acid copolymer made by `
The Dow Chemical Company having a Ml of about 300 g/10 min - ~ ~ and about 20 weight percenl acrylic acid content ~o Polyester. ~ Dow Research Material Polyester l B900~02RUl ~.
Po1yol: leffamine~9 M-2005 made by Texaco `
Talc: Microtuff~ 1000 by Pflær TPU: Thermoplastic Polyurethane made by The Dow Chemical Company and trademarked Pellethane TPU-80A: PELLE~ANE~92102-80A
TPU-9OA: PEELErHAN~9 2102-9OA
C: Indicates a comparative example; not an example of the invention SUBSTITUTE SHEE:T

W O 93/25617 ~ 1 3 7 ~ :~ PC~r/US93/05363 Re~ults and ConclusiQns In Tables lA and lB, column 1 reports the composit:ion of each of the blends. The legend for these compositions is reported in Table lC.
Column 2 reports the nature of the paint by curing temperature; column 3 ;
s the actual curing oven temperature; and column ~ the test results. -In column 4, ~4~ means that the painted plaque passed the crosshatch and o dime scrape tests in both the initial test and after the water immersion test;

~3u means that the painted plaque passed both initial tests but failed either the crosshatch or dime scrape test after the :~
s water immersion test; ;~
:
~2~ means that the painted plaque passed both initial tests but failed both the crosshatch and dime scrape tests after the water lmmersion test;

~1' means that the painted plaque failed one of the initial crosshatch or dime scrape tests; and ~
, .' ~; '0~ means that the painted plaque failed both initial tests.
:
25~ ~
Mo}ding conditions directly in1uence the surface properties and thus the paintability of the plaques. Compression molding equipment heat the samples f~rom the free suraces eO the bulk. Injection molding equipment, after~melting the pellets, cool the moldings from the free surface to the bulk. The pressure of the two moldings are also different as ;is the shear ratio. For a PE having a MI of 10 g/10 min, the shear ratio for injection molding is about 2000-5000/sec. The effects of these ;
two different thermal and mechanical histories can be seen in the results reported in Tables lA and lB. For example, C-1, prepared by injection molding, reports only marginal paint adhesion while Ex. 26, prepared by compression molding, reports essentially perfect adhesion.

. ~:

W O 93J25617 2 1 3 7 2 8 3 ` P ~ /US93/05363 ~

The effect of the molding surface on the paintability of the plaque is seen in a comparison of C-24 with Ex. 7, and of Ex.11-12 with C-34. In the first comparison (between injection molded samples~, the plaque of Ex.
s 7 outperformed the plaque of C-24 even though both failed to demo~nstrate an acceptable level of paint adhesion. The crosshatch and tape peel test has scores that range from 0 to 5B, and any score below 3B fails the test.
The plaque of Ex.~7 scored a 2B, but the plaque of C-24 scored a 0. These results show that the Mylar surface imparted some improvement to the paint adhesion properties of the plaque.

Similar effects in compression molded plaques are reported in Ex.
11-12 and C-34, but here the results are more marked. Ex. 11-12 report essentially perfect adhesion, while C-34 (prepared with a Teflon~ - coated 15 mold surface) reports virtually no adhesion.

Examples 1-6 report acceptable paint adhesion results on plaques made by injection molding. Controls 1-27 report unacceptable paint `
adhesion results, and most, if not all, of this can be attributed to the 20 method of fabricatlon (injection molding). Similar compositions, as shown ;~
aboYe, made by compression molding techniques demonstrate acceptable paint adhesion properties.

~ Ex~mples 8-42 show that plaques made from a wide variety of 2s ~compositions demonstrate excellent paint adhesion properties when made by ~`
compression molding. These compositions include simple g-PE diluted or let down with LLDPE ~Ex. 8-9) or HDPE (Ex. 10), g-PE itself (Ex. 11-12), -~
and blended with various thermoplastic polymers or simply fillers, for example, polyamide (Ex. 16-17), epoxy ~Ex. 18-19), nylon (Ex. 26), -fiberglass (Ex. 13-14), talc ~Ex. 29-30), etc.

Controls 28-29, 31-i3, and 35-42 show the effect of using an !
ungrafted polyethylene, alone or blended with various thermoplastic ~ `
polymers or fillers. -~

';
, ~.

-16- ~

W O 93/25617 2 ~ 3 7 2 8 3 PCI`/US93/05363 Ex. 42a and 42b: Additional Automotive Paint Adhesion Tests In both Examples, a one to one blend of HDE.04 and P1410 (see legend of Table lC) was prepared, 6.5~ x 2.5~ x 0.075U plaques of the blend were ' s made by injection molding, the plaques painted with a white top coat (no promoter, no primer) of the two-component polyurethane system described in Ex. 1-42, and then tested, all by the procedures described for Ex. 1-42.
Perfect paint adhesion was achieved in both examples.
~ ,.
, ~,.,,,~
Ex. 43-4~ and Cntrls C-~3 to C-~5: Adhesion of Polyethylene to Rigid Polyurethane Foam Sam~le PreDaration ;
~ ' ';,' The rigid polyurethane foam was an appliance polyether polyol/PMDI --based~formulation of The Dow Chemical Company utilizing two different ~';`
hydrochlorofluorocarbon blowing agents.~ Final in-place foam densities were io the rànge~of 2.~ 33.64~kg/m3)to 2.2 1b/ft3 (35~.24~kg/m3) inorder to aæsure~freeze~stabi~1~ity of~the~foam samples. These samples were prepared -~
utilizing~a~Bret~t~mold~which is standard industry~equ~ipmènt for ~~
`det ~ ~ ~ e ;flow~characterlst~ics of r1gld polyurethane foams. The polyethylene~panels were mounted ~in the bottom, middle and top of the 8rett~mold~for foaming such~that the effects of variations in foam density and~texture~cou1d be~assessed~ The results of the adhesion tests are reported~in~Table 2.

~" ~ ''`

W O 93/25617 ~ ~ 3 7 2 8~3 PCT/US93/0536 ADHESION OF POLYETHYLENES TO POLYURETHAN~
Ex./
Control Polyethylene Substrates Sample Sample #l #2-~

0 C-43 HDPE 25055 Fail Fail :~
C-44 Dowlex~ 2047 Fail Fail ~3 HDG.0l Pass Pass 44 HDG.0l~Dowlex~ 2047=4J6 Pass Pass ~ -~
C-45 HDG.0l/Dowlex~ 2047=l/9 Fail Fail The legend for the various compositions is in Table lC. ~Pass~
indi~ates perfect adhesion, that is, under stress the polyurethane foam fails before the interface between the foam and the g-PE. ~Fail~
indicates imperfect adhesion, that i9, under stress the interface between the foam and the g-PE fails before the foam. As the results of Table 2 ``~
report, g-PE demonstrates excellent adhesion properties to polyurethane ~foams~prepared with ~hydrochlorofluorocarbon blowing agents, while the --25~ ungra~fted polyethylene did~not. C-4;5 demonstrates that the g-PE is preferably~present is~certain~minimum amounts.

:: . . ~., Ex.~ 45-46;and~Cntr1s C-46 and C-47: Polyethylene/Wood Fiber Blends Sam~1e PreDaration Polyethylene and cedar fiber melt blends were made on a Haake 90 system operated at l90~degrees C and 60 rpm for 5 minutes. The Haake was heated to~th~e~run temperature, and then the polyethylene was added and `
~alIowed to melt with blending. The cedar fibers were then added and melt ;~
blended for~5 minutes. The mlelt blends were then extruded into sample sizes suitable for testing, the resuits of which are reported in Table 3.
~..
LDPE 723 is a branched PE homopolymer made by The Dow Chemical Company having a MI of about 8 9/l0 min and a density of about 0.916 s~cm3.
~ ~ ,' ' ` `

-18- ;

.~:

W O 93/25617 ~37 ~83 P ~ /US93/05363 TABLE 3 v TENSI~E STRENGTH AND PA~ ADHESION
OF CEDAR-FIBER/POLYETHYLENE BLENDS
Part A. Using Raw Cedar Fiber and Virgin Polyethylenes Ex.~ Tensile Elongation Density Control (kpsi) (percent) (g/cc) 1 0 . ~
C-46* 0.61 (g,202.9 kP) 1 1.034 45** 1.94 (13,366.6 kP) 1 1.033 ~
Part B. Using Refined Cedar Fi~er and Virgin Polyethylene ~ -Ex./ ~Tensile Elongation Density -~Control (kpsi) (percent) (g/cc) ' ;

C-47* 0.75 (5,167.5 kP) 1 1.059 46** I.72 (11,850.8 kP) 1 1.059 * 50 percent fiber + 50 percent LDPE 723 2s ** 50 percent fiber + 40 percent LDPE 723 + 10 percent HDG.04 -~
, j:

As~reported in Table 3, the~presence of g-PE in the blend ~ signific~antly increases the tensile strength of the composite without -~
- 30 adversely~ impacting~lts elongation and density properties. The effect is present in~c~omposit-es of both raw and refined wood fibers.

Alth4ugh~;the invention has been described in detail by the preceding `-xamples,~such d-tail is for the purpose of ilIustration only and is not -;
to be construed as a ~imitat~lon~upon the invention. Many variations can ~`
be made upon the preceding examples without departing from the spirit and ~-; , ~ scope~of the followin~ claims.~ ~ ~

.--:~, : -.~ -''~'- ' ' ~ S -`~`'`
..

- 1 9 - , ~ ,

Claims (13)

WHAT IS CLAIMED IS:

1. A paintable thermoplastic composition comprising:
A. At least about 50 wt % polyethylene grafted with at least about 0.01 wt %, based on the weight of the polyethylene, of an organic compound containing at least one double bond and at least one acyl group; and B. At least about 5 wt % of at least one ethylene interpolymer selected from the group consisting of ethylene/acrylic acid, ethylene/methacrylic acid, and ethylene vinyl alcohol.

2. The composition of Claim 1 in which the unsaturated organic compound is selected from the group consisting of maleic acid, fumaric acid, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, .alpha.-methyl crotonic acid, cinnamic acid, maleic anhydride, and mixtures thereof.

3. The composition of Claim 2 in which the polyethylene, prior to grafting with the organic compound, has a density between about 0.941 and about 0.965 g/cm3.

4. The composition of Claim 3 in which the organic compound is maleic anhydride.

5. The composition of Claim 4 in which the polyethylene, prior to grafting with organic compound, has a density between about 0.95 and about 0.965 g/cm3.

6. The composition of Claim 5 in which the polyethylene is grafted with at least about 0.1 wt % of maleic anhydride.

7. The composition of Claim 1 in which the ethylene interpolymer has a melt index between about 0.05 and about 1300 g/10 min.

8. The composition of Claim 7 in which the grafted polyethylene comprises at least about 70 wt % of the composition.

9. The composition of Claim 1 further comprising an inert filler.

10. The composition of Claim 10 in which the filler comprises at least about 5 wt % of the composition.

11. The composition of Claim 11 in which the filler is talc.

12. An injection molded article prepared from the composition of Claim 1.

13. An injection-molded article prepared from the composition of Claim 12.