CA1334709C - Ethylene-acrylic acid type interpolymer compositions and films having increased slip and reduced block - Google Patents

Abstract

A composition comprising in intimate admixture (a) at least one copolymer of from 2 to 35 weight percent acrylic or methacrylic acid and 98 to 65 weight percent ethylene having a melt flow volume of from 0.01 to 50 dg/min; and being prepared by interpolymerization at a reactor temperature and pressure above its two-phase transition zone, and, (b) from 0.05 to 2 percent, by weight of the composition, of at least one secondary fatty acid amide of the formula R5-CO-NH-R6 wherein R5 is a mono-olefinically unsaturated alkyl group having from 17 to 23 carbon atoms and R6 is a mono-olefinically unsaturated alkyl group having from 18 to 24 carbon atoms. The polymers are preferably prepared at a tem-perature and pressure above the two-phase transition zone. The compositions are useful for making films and in extrusion coating of various substrates.

Description

1 74069-9lE
Thls appllcatlon ls a dlvlslonal appllcatlon of Canadlan Patent Appllcatlon 616,517 flled on 17 November, 1992 whlch ltself ls a dlvlslonal appllcatlon of Canadlan patent appllcatlon 556 806 flled on 19 January 1988.
Thls lnventlon relates to composltlons of ethylene lnterpolymerlzed wlth acryllc acld, methacryllc acld and lonomers thereof whlch contaln addltlves for substantlally reduclng the block and/or lncreaslng the sllp characterlstlcs of fllms and coatlngs made from the composltlon.
Fllms made from varlous ethylene lnterpolymers, vlz ethylene-acryllc acld, ethylene-methacryllc acld and lonomers thereof are well known. Such lnterpolymers are prepared commer-clally ln hlgh pressure reactors at elevated temperatures ln the presence of free radlcal catalysts. Dependlng on the condltlons of synthesls, the lnterpolymer may be composltlonally unlform and elther random or non-random, or lt may be composltlonally non-unlform.
As descrlbed ln Unlted States Patent No. 4,248,990, by composltlonally unlform lt ls meant that substantlally all of the polymer molecules have substantlally the -same chemical composition while the molecular weight thereof may vary. Randomness is generally me,asured by the ratio of percent adjacent interpolymerized acid to total percent interpolymerized acid in the inter-polymer. When this ratio is above 0.44 theinterpolymer is considered to be non-random, while below 0.44 it is considered to be random.

Also as described in U.S. Patent No. 4,248,990, the synthesls condltions will determine whether the interpolymerization is one-phase operation or two-phase operation. Generally, as the pres~ure and temperature of the reactor are reduced, there will be a transition from one-phaqe operation to two-phase operation evidenced by an increase in initiator demand, development of a significant temperature spread in the reactor, and the requirement of more power to maintain constant agitator speed, while the interpolymer product will exhibit a narrower molecular weight distribution, a decrease in the slope of the shear rate-shear stress curve for the melt, an increase in the environmental stress crack resistance, an increase in the maximum draw rate for film or filament, and an increase in the ratio of percent adjacent acid to percent total acid.
The interpolymer produced in two-phase operation will be compositionally non-uniform, while that produced in one-phase operation will be compositionally uniform.
In one-phase interpolymerization just above the 3 transition zone, the interpolymer product will be non-random, but will be increasingly random as the pressure and temperature are elevated above the transition zone.
At pressures more than 3.3 MPa above and temperatures more than 15C above the transition zone, the interpolymer is substantially random. When the 33,218A-F -2-synthesis conditions are at least 26.7 MPa above and 20C above the transition zone, the interpolymer product exhibits superior physical properties and surprisingly excellent optical properties. These superior random ethylene interpolymers and their method of preparation are disclosed in U.S. Patent 4,599,392.

Varlous additives for improving slip and antiblocking characteristics of ethylene interpolymers containlng acrylic acid, methacrylic acid and ionomers thereof have been known. Some of these were known before the above described effect of synthesis conditions on interpolymer properties was known. For example, U.S. Patent No . 3,597,382 described ethylene copolymers containing 2 to 25 weight percent of an a,~-ethylenically unsaturated carboxylic acid copolymerized therein and having a melt index of 0.01 to 50 dg/min, or inorganic salts thereof, in which the slip characteristics were improved by incorporating therein 0.02-l.0 weight percent of a secondary fatty acid amide of the formula R1-C0-NH-R2 wherein Rl was a mono-olefinically unsaturated hydrocarbon radical having 20 to 24 carbon atoms and R2 was saturated alkyl group 25~ having 14 to 26 carbon atoms. Secondary fatty acid amides in which Rl was saturated and in which R2 was mono-olefinically unsaturated were reported to be ineffective in improving the slip characteristics of the ethylene interpolymers into which it was 3 lncorporated-Similarly, U.S. Patent No. 3,595,827 describedethylene interpolymer compositions containing in addition to the secondary fatty acid amide of U.S.
Patent No. 3,597,382, 0.01 to 2 weight percent of synthetic amorphous silica having a surface area of 175 33,218A-F -3-74069-glE

to 400 m /g, a pore size of 80 to 250 A, at an average particle size of 0.5 to 8 mlcrons which synergistically improved the slip characteristics of the ethylene interpolymers, and also improved the antiblocking characteristics thereof.
Because of the state of technology at that time, it is believed that the ethylene interpolymers employed in the composi-tions in United States Patent Nos. 3,597,382 and 3,595,827 were compositionally non-uniform, prepared in two-phase operation.
In one aspect of the invention of the parent application, it has been discovered that the slip and/or block character-istics of a polar ethylene interpolymer, regardless of the synthesis conditions thereof, are synergistically improved when there is compounded therewith a saturated secondary fatty acid amide of the formula Rl-CO-NH-R2, wherein Rl and R2 are both saturated alkyl groups and an unsaturated or mixed unsaturated secondary fatty acid amide of the formula R3-CO-NH-R4, wherein R3 and R4 are alkyl groups, at least one of which is mono-olefini-cally unsaturated. In addition, the slip and/or block characteristics of the ethylene interpolymer are further improved by compounding therewith finely divided inorganic.
In the invention of this divisional application, it has been discovered that the handleability characteristics of an ethylene interpolymer, regardless of the synthesis conditions thereof, are improved when the interpolymer has compounded there-with an unsaturated secondary fatty acid amide of the formula R5-CO-NH-R6, wherein R5 and R6 are alkyl groups which are mono-74069-9lE
oleflnically unsaturated.
In the inventlon of dlvlsional appllcatlon 616,517, lt has also been dlscovered that the handleablllty characterlstlcs of a polar ethylene lnterpolymer prepared above the two-phase transl-tlon zone are lmproved when the lnterpolymer has compounded there-wlth a mixed unsaturated secondary fatty acid amlde of the formula R7-CO-NHR8, whereln R7 ls a saturated alkyl group and R8 ls a mono-oleflnlcally unsaturated alkyl group. In addltlon, the sllp and/or block characterlstlcs of the composltlonally unlform ethy-lene lnterpolymer are further lmproved by compoundlng therewlth aflnely dlvlded lnorganlc.
The types of ethylene lnterpolymers whlch may be employ-ed ln the composltlon of the lnventlons are the composltlonally unlform lnterpolymers, lncludlng the non-random, random, and superlor random lnterpolymers, and also the composltlonally non-unlform lnterpolymers, wlth the superlor random ethylene lnter-polymers belng preferred. As used hereln, the term "composltlon-ally non-unlform" ls used ln reference to ethylene lnterpolymers prepared below the two-phase transltlon zone. The term "non-random" ls used ln reference to the composltlonally uniformethylene interpolymers which have been prepared ~ust above the two-phase transltlon zone, l.e. 0 to 3.~ MPa and 0 to 15C
thereabove, and whlch have a ratio of percent interpolymerized ad~acent acld to the total percent lnterpolymerlzed acid of 0.44 to 1Ø The term "superior random" is used in reference to the compositionally uniform ethylene interpolymers which have been prepared well above the two-phase transltion zone, i.e. at least 26.7 MPa and 20C thereabove, and which have a ratio of percent interpolymerized acid less than 0.44. The term "random" is used in reference to the compositionally uniform ethylene interpolymers, excluding the superior random interpolymers, which have been prepared above the two-phase transition zone, i.e.
at 3.3 to 26.7 MPa or 15 to 20C thereabove, and which have a ratio of percent interpolymerized adjacent acid to the total percent interpolymerized acid less than 0.44. The term "compositionally uniform" is used collectively in reference to the non-random, random and superior random ethylene interpolymers prepared above the two-phase transition zone.

Regardless of the type of ethylene interpolymer employed, it will have acrylic acid or methacrylic acid interpolymerized therein. The amount of acrylic acid or methacrylic acid interpolymerized in the ethylene-acrylic acid or -methacrylic acid interpolymers employed in the composition may be from 2 to 35 percent by weight of the interpolymer, preferably from 5 to 20 percent by weight of the interpolymer.

Also suitable as the interpolymer in the composition of the inventions are the inorganic salts, or "ionomers", of the ethylene-acrylic acid interpolymers and the ethylene-methacrylic acid interpolymers with the acid content described above in which from 5 to 95 percent of the carboxyl groups therein are neutralized with metal cations to form ionically cross-linked products. Representative metal cations include, for example, cations of zinc, sodium, magnesium, potassium, lithium, calcium, barium and the 33,218A-F -6-,~

-like. For convenience, these inorganic salts are collectively referred to hereinbelow as ionomers.
The melt flow value of the ethylene interpolymers employed may be from 0.01 to 50 dg/min, preferably from 0.5 to 25 dg~min. As used herein, melt flow value is measured according to ASTM D-1238 condition E (190C/2.160 kg) unless otherwise indicated.
The secondary fatty acid amides which may be employed in the compositions have the general formula:
RCONHR' wherein R is a saturated alkyl group having from 11 to 25 carbon atoms and mono-olefinically unsaturated alkyl groups having from 17 to 23 carbon atoms, and R' is a saturated alkyl group having from 12 to 26 carbon atoms and mono-olefinically unsaturated alkyl groups having from 18 to 24 carbon atoms. As used in this detailed description to describe the secondary fatty acid amides unless otherwise noted, the term saturated" refers to the secondary fatty acid amides in which both R and R' are saturated;
the term ~unsaturated" refers to the secondary fatty acid amides in which both R and R' are mono-olefinically unsaturated; and, the term "mixed unsaturated" refers to the secondary fatty acid amides in which either R or R' is mono-olefinically unsaturated and the other R or R' is saturated.
Representative specific examples of amide groups containing a saturated alkyl group corresponding to R in the secondary fatty acid amides include lauramide, palmitamide, stearamide, arachidamide, behenamide, lignoceramide and cerotamide.

33,218A-F -7--~' Representative specific examples of amide groups containing an unsaturated alkyl group corresponding to R in the secondary fatty acid amides include oleamide, elaidamide, vacenamide and erucamide.
Representative specific examples of saturated alkyl groups corresponding to R' in the secondary fatty acid amides include lauryl, palmityl, stearyl, arachidyl, behenyl, lignoceryl and cerotyl. Representative specific examples of the unsaturated alkyl groups corresponding to R' in the secondary fatty acid amides include oleyl, elaidyl, vaccenyl and erucyl.
The finely-divided inorganics which may be employed in the composition of the invention are, for example, naturally occurring clay, aluminum silicate, diatomaceous earth, silica, talc, limestone, fumed silica, magnesium sulfate, magnesium silicate, alumina trihydrate, magnesium oxide and zinc oxide, with siliceous materials being preferred. The finely-divided inorganic preferably has a surface area of from 0.7 to 7.5 m2/g, an oil absorption value of from 21 to 175 g oil per 100 g inorganic, and a weight average particle size of from 0.02 to 30 microns with at least 60 percent of the inorganic particles being less than or equal to the weight average particle size.
One or more of the secondary fatty acid amides are employed in the composition in an amount of from 0.05 to 2 percent by weight of the composition. Used alone, the saturated secondary fatty acid amides function primarily to reduce the block characteristics (i.e. to improve the antiblock characteristics) of the interpolymer, whereas the unsaturated and mixed unsaturated secondary fatty 33,218A-F -8-- _ 1 334709 g acid amides function primarily to increase slip characteristics.

The 91ip and/or antiblock characteristics of the compositionally non-uniform, the non-random, the random, and the superior random ethylene interpolymers are synergistically improved when a saturated secondary fatty acid amide is employed in the composition, preferably in an amount of from 0.025 to l percent by weight of the composition, in combination with either an unsaturated or a mixed unsaturated secondary fatty acid amide, preferably in an amount of from 0.025 to l percent by weight of the composition. This is a synergistic result in that, at the same concentration of total additives, this combination of secondary fatty acid amides results in slip and/or antiblock characteristics which are more improved than when any type of secondary fatty acid amide is used alone.
The slip and/or antiblock characteristics of the composition are further improved when a finely-divided inorganic i~ employed "preferably in an amount of from 0.025 to 1.5 percent by weight of the composition, either with the combination of saturated with unsaturated or mixed unsaturated secondary fatty acid amides. A synergistic improvement is also observed when the inorganic is employed with the saturated secondary fatty acid amides alone, but the resulting slip characteristics of the composition are not generally commercially acceptable unless an unsaturated or mixed unsaturated secondary fatty acid amine is also present.

33,218A-F -9-74069-9lE
In addltlon, the optlcal propertles of the composltlon are not substantlally dlfferent from those of the ethylene lnter-polymer wlthout the addltlves.
In contrast to the composltlonally non-unlform ethylene lnterpolymers ln whlch, accordlng to U.S. Patent 3,5g7,382, only the mlxed unsaturated secondary fatty acld amldes of the above formula whereln R ls unsaturated and R' ls saturated are effectlve ln lncreaslng sllp, lt has been found that certaln unsaturated secondary fatty acid amldes are effectlve ln lmprovlng sllp characterlstlcs of the ethylene lnterpolymers descrlbed above.
For the composltlonally unlform lnterpolymers, the unsaturated secondary fatty acid amlde employed ln the lnventlon of thls dlvlslonal appllcatlon has the formula whereln R5 ls a mono-oleflnlcally unsaturated alkyl group havlng from 17 to 23 carbon atoms, preferably 19 to 23 carbon atoms, and especlally 21 carbon atoms, and R6 ls a mono-oleflnlcally unsatur-ated alkyl group havlng from 18 to 24 carbon atoms, preferably 20 to 24 carbon atoms, and especlally 22 carbon atoms. For the com-posltlonally non-unlform lnterpolymers, R5 ln the above formula should be a 19 to 23 carbon atoms unsaturated alkyl group, prefer-ably 21 carbons, and R6 should be 20 to 24 carbon unsaturated alkyl group, preferably 22 carbons.
Also ln contrast to the U.S. patent 3,597,382, lt has been found that a mlxed unsaturated secondary fatty acld amlde employed ln the lnventlon of dlvlslonal appllcatlon 616,517 of the formula wherein R7 is a saturated alkyl group having 13 to 25 carbon atoms, preferably 17 to 25 carbon atoms, and R6 is a mono-olefinically saturated alkyl group having 18 to 24 carbon atoms, preferably 20 to 24 carbon atoms, and especially 22 carbon atoms, are effective in improving the slip characteristics of compositionally uniform ethylene interpolymers to a commercially acceptable extent.

In the single additive system, the higher molecular weight secondary fatty acid amides appear to be more effective than the corresponding low molecular weight additive~. Generally, the more random the ethylene interpolymer, the more polar the interpolymer, and hence the leqs "soluble" the higher molecular weight aqditive, and e~pecially the higher molecular weight amide substituent (R5) of the additive. The less soluble the additive, the better the "bloom," and hence, the better lmprovement in slip characteristic~.
Thus, higher molecular weight additives such as erucyl stearamide are generally effective in all composition-ally uniform ethylene interpolymers, whereas the lower molecular weight additives such as oleyl palmitamide are generally only effective in the superior random ethylene interpolymers. Similarly, erucyl erucamide is ~generally effective in compositionally uniform and non-uniform interpolymers, whereas oleyl oleamide is generally effective in the superior random 3 interpolymers but generally ineffective in the compositionally non-uniform lnterpolymers.

The compositions according to this invention are readily prepared by intimately admixing the ethylene interpolymer with the secondary fatty acid amides and any inorganic. Mixing of the required 33,218A-F -11-components is readily carried out in a conventional mixing apparatus such as Banbury mixer or screw-type extruder.

The films according to this invention are readily prepared by extruding the resulting mixture in the form of a clear, fiexible, blown bubble tube which is subsequently cooled and collapsed onto rolls or is collapsed and conveyed through appropriate heat sealers and cutters, packaging and packaging structures where the ethylene interpolymer composition is employed at thicknesses in the range of 0.0025 to 0.3 mm. The compositions may also be employed in co- and multilayer extrusions and coatings.
In one embodiment, wherein the mixing device is a screw-type extruder, the additives are fed into the barrel of the extruder. The extruded mixture may be mixed with additional interpolymer(s) prior to final extrusion or may be fed directly into an extruder equipped with an annular die and extruded in the form of an inflated bubble or thin wall parison.

In a preferred embodiment, the mixing and extruding steps are carried out in a single apparatus which is a typical screw-type extruder that is equipped with a circular die and feed means placed along the extruder barrel which houses the screw or ~crews of the extrude~r. The secondary fatty acid amides and any inorganic are introduced as the polymer is being extruded at a rate such that a constant mixture is maintained. Similarly, concentràted master batches can be added to virgin material in the screw-type extruder.

33,218A-F -12-~ The slip and block characteristics of the composition are tested by compounding the additives with the ethylene interpolymer and extruding the mixture into film by the blown film method.

The slip characteristic is delineated by the coefficient of friction (COF) which ls measured on a flat, highly polished horizontal metal plane using a specimen "sled", a strain cell with a O to 300 gram range connected to a 10 millivolt recorder, and a driving force which moves the plane at the rate of 2.54 cm per 10 seconds. The sled is a 200 gram flat slab of stainless steel measuring 6.35 cm by 6.35 cm by 0.635 cm thick with the bottom surface covered with a sheet of sponge rubber. The specimen film which measures the 10.2 cm by 10.2 cm is first conditioned at 23C and 50 percent relative humidity for 8 hours before testing, and is then affixed against the sponge rubber surface of the sled. The sled with the specimen attached thereto is connected to the strain cell with the specimen in contact with the plane. Film-to-film measurements are made by covering the plane with the same film from which the specimens were obtained; film-to-metal measurements are made by placing the specimen affixed to the sled directly on the metal surface of the plane. The driving force moves the plane horizontally and the sled is held stationary by the strain cell. The pulling force against the strain 3 cell, caused by friction between the sled and plane, is recorded. The initial maximum peak reading is taken as the state force at which the relative movement between the film/film or film/metal surfaces begins. Kinetic force, the amount of force required to maintain the relative movement after it has started, is taken as the 33,218A-F -13-average of ~even 2.54-cm-spaced readings from the recorder. The static and kinetic coefficients of friction are then computed by the following equations:

S~atic COF = (static force, g)/(200 grams); and ~inetic COF = (sustained motion force, g)/(200 grams).

A film-to-film COF of less than 0.30 and a film-to-metal COF of less than 0.49 generally permit good handling for packaging processes.

Blocking is measured by employing a balanced beam which is provided with an empty water reservoir dangling from one end and a block measuring 9.525 cm by 9.525 cm by 2.54 cm (about 91 cm2 face) dangling from the other end. Immediately below the 91 cm2 block is a similar 91 cm2 block, the two 91 cm2 flat surfaces just touching together when no weight is applied to either end of the balance beam. The lower block is fixed and does not move. The balance beam rests on a blade-edge fulcrum and is very sensitive to small weights. Two film qpecimenq, each measuring about 15.2 cm by 15.2 cm are brought together qo that a complete side or face of one specimen is totally against a complete side or face of t-he other. The two-ply specimen so formed is centered between the two 91 cm2 blocks with the two ~blocks touching the upper and iower surfaces of the two-ply specimen, respectively. The protruding edges of the two-ply ~pecimen are separated from each other by hand and the freed edges of the upper ply are fixed to the outer edges of the upper block and lower block respectively, e.g. with a rubber band or adhesive, leaving the 91 cm2 portion of the two-ply specimen still clinging, ply-to-ply between the blocks. When the specimen is ready for testing, the restraint on the 33,218A-F -14- , beam is removed and water is rapidly dripped into the reservoir on the other end of the beam. For consistency from test to test, the rate of water dripping is at a substantially constant rate such that the drips are too fast to be easily counted. When the two plys of film become parted, the water addition is stopped and the weight of water in the reservoir is determined in grams. Each test of block is repeated a ~, plurality of times and results averaged. As reported herein, the block values are taken as the average of four specimens unless otherwise indicated.

From experience, the following approximate block ranges may be arbitrarily assigned the corres-p,onding relative effect on handleability andprocessing, although these ranges may change depending on the particular equipment and film compositions employed:

33,218A-~ -15--16- ~ 1 3 3 4 7 09 APProx. Block Ran~e (~) Relative Effect About 40 to about 100 A good 2Icceptshle range which generally gives no h~n~lin~ or unwinding problems.
About 100 to about 150 A high block range where one may encounter some h~n~3lin~ and ~lignment problems as well as slower and jerky unwinding.
Greater than 150 An excessive block range wherein h~n~ling problems are very pronounced and unwinding is seriously hampered; with very thick films one may encounter destructive block where unwinding causes tears or stretching and roll stock may completely solidify.

Film gloss and percent haze are determined according to ASTM D- 1746 and ASTM D- 1003-52, respectively The following examples are given as illustrations of the inventions. Throughout this specification and claims, all parts and percentages are by weight unless otherwise indicated.
Experiment I

A blown film sample was prepared by first compounding the following recipe 177C in a 6.35 cm, 20/1 L/D compounding extruder that was equipped with a metering, compression and mixing section;

33,218A-F -16-0.3 parts oleyl palmitamide;
0.2 pa~ts stearyl stea~amide;
0.1 parts diatomaceous earth (obtained under the designation Celite'~ 45~); and 49.4 parts ethylene-acrylic acid interp~lyme~
(app~oximately 9 veight percent acrylic acid, melt Clo~ value 1.5; p~epared at single phase synthesis conditions abo~t 26.7 MPa above and about 20~C above its respective phase transition zone).

The pelletized product from the extruder was fabricated into 61 cm lay flat film by usual inflation techniqueq on a 5.08 cm Cloucester blown film unit at 204C plastic temperature. The resultant film sample posseqqed a film-to-film kinetic and static COF of 0.15 and 0.18, respectiYely, a 20 film gloss of 23.7 a film haze of 5.70 percent and 43 grams of film blocking.
In comparison thereto, the above procedure was performed utilizing the qame ethylene-acrylic acid interpolymer without the inclusion of the amides or the diatomaceous earth. The requltant film had severe handling problems (i.e., a film-to-film kinetic and static COF of 1.16 and 0.97, respectively, and 159 grams fllm blocking) with substantially équivalent optical properties (i.e., a 20 film gloss of 21.6 and a film haze of 5.5 percent).

Experiment II

i The procedure of Experiment I was employed to demonstrate the synergistic effect of the amides and inorganic in the composition. A similar ethylene interpolymer (9 weight percent acrylic acid, melt flow 33,218A-F -17-~.~

value 3.0, synthesis at 26.7 MPa above and 20C above its respective phase transition zone) was used to prepare the films with and without various combinations of amides and/or inorganic at the same concentration of total additives. The composition and handling and optical characteristics are summarized in Table I. As can be seen, a combination of any two of any of the three additives (oleyl palmitamide, stearyl stearamide and inorganic) results in improved slip characteristics in comparison to either one or the additives alone;
however, only combinations of the saturated amide with the mixed unsaturated amide, or of saturated amide and the mixed unsaturated amide with the inorganic, resulted in films with acceptable block and optics, as well~as slip.

33,218A-F -1 8 -s TA0LE I
Coefficient of Priction5 1 Amide, ppm Inorganic, Film-to-Film Film-to-Metal ~10ck 6 Gloss7 Run op2 SS3 ppm4StaticKineticStaticKinetic ' q 20 45 3~ None None None 1.26 1.16 0.301.17 279.3 29.0 65.0 4 8000 None None 0.20 0.17 0.260.39 139.4 22.5 59.3 5~ None 8000 None 0.60 0.80 0.27~ 0.35 66.2 32.5 67.3 6* None None 8000 0.75 0.79 0.250.20 63.3 21.2 55.4 7 4000 None 4000 0.17 0.16 0.260.22 123.3 23.3 58.0 8~ None 4000 4000 0.36 0.39 0.180.28 86.7 24.9 59.6 9 4000 4000 None 0.15 0.25 0.130.38 86.8 22.8 65.5 10 3500 3500 1000 0.15 0.23 0.120.21 89.4 ?5-9 61.9 Notes for Table I:
1. Films made from an ethylene-acrylic acid interpolymer containing about 9 weight percent acrylic acid, havinq a melt flow value of about 3, and prepared at 26.? MPa above its respective two-phase transition zone.

2. Oleyl palmitamide. W

3. Stearyl stearamide.

4. Diatomaceous earth obtained under the desiqnation Celite 455.

5. See above for description of COF measurements. ~

6 See above for description of block measurements. ~J

7. ASTM D-1746. o 8. ASTM D-1003-52. - ~D
This composition is not within the scope of this invention; data supplied for purposes of comparison.

~ 334709 , Experiment III

, The procedure of Experiment I was further employed to demonstrate that an unsaturated amide (erucyl erucamide) in combination with a saturated amide (stearyl stearamide) is similarly effective in comparison to the mixed unsaturated amide in which R is saturated and R' is un~aturated (oieyl palmitamide in Table I or erucyl stearamide in Table II) in combination with the same saturated amide (stearyl stearamide). The compositions and handleability and optical characteristics are summarized in Table II.

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~ 334709 Experiment rv Additional data confirming the resultq of Experiments I, II and III was obtained by employing films and procedures similar to those of Experiments I, II and III except that the ethylene-acrylic acid interpolymer had a melt flow value of 2.5, contained 6.5 weight percent acrylic acid and was prepared at 31.0 MPa and 25C above it9 respective phase tran~ition zone, and that the interpolymer was fabricated into 12.7 cm layflat film on a 1.27 cm blown film unit made by Killion Extruders Inc. at 204 C plastic temperature.
The re~sults presented in Table III fu~r demanstrate the synergism observed in Tables I and II for the saturated secondary fatty acid amide in combination with the unsaturated or mixed unsaturated fatty acid amide where R i~ a mono-olefinically unsaturated alkyl group and R' is a saturated alkyl group (stearyl erucamide), with or without finely-divided inorganic. It should be noted that for this particular equipment, the low block range was observed to be approximately 20 to 75, high block was approximately 75 to 125, and excessive block was greater than about 125.

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E- . v E U c ~ ~ ,1 E ~ o ,., ,~ ~ V . ~ c .,1 ~ , o ~ o ~ ~

t U _~ O
~ I U~
f U~l O O O O O U ~
`; C~ O ~ ~ o O O _~ U
f`~ ~ t-l r ~ O J~
/~J 'O O ''~
L C U ~ C
.rl ~ O O V
0 0 o o o o o ~ ~ ,~

fl ~ ~ . Ll L~ Ul f,~ - aCJ U~ v uu~ u ~
I o o o o o ~~ o O ~ E ~ ~ ~ ~ ~ o ta r~ ~o ~ l ~o ~ ~ rrl u~
o 0 0 n o u~ ~ o o ~ ~ n o a a o u~ ~ L ~ ~ a~
U la v C~ o ~ ~ f ~ ~ a~ v ~ t-2 r~ f,~

. -24-Experiment V

The procedure of Experiment I was employed to demonstrate the erfectiveness of certain amides used alone as additives for a superior random ethylene interpolymer (9 weight percent acrylic acid, melt flow value 3.0, prepared at 26.7 MPa above and 20C above its .respective phase transition zone), and also for a random ethylene interpolymer (9 weight percent acrylic acid, melt flow value 3.0, prepared at 3.3 MPa above and 15C above its respective transition zone). The composition and slip characteristic~ are summarized in Table IV. Note that erucyl erucamide and erucyl stearamide in contrast to the lower molecular weight oleyl oleamide and oleyl palmitamide, which were ineffective in the compositions of U.S. Patent No.
3,597,382, are effective in the random ethylene interpolymer composition of the present invention.
These results are rather surprising in that, si'nce the compositionally uniform interpolymers generally result in smoother film surfaces with concomitantly higher COF's, the superior random interpolymer resulting in even smoother film surfaces than the random interpolymers, it would be expected that the handling properties of ~uch compositions would be more difficult to improve.

33,218A-F -24-TABLE IV
Coefficient of Friction6 Amide Film-to-Film Film to Metal Run Interpolymer Type ppm Static Kinetic Static Kinetic 27~ Al -- 0 1.40 1.40 0.60 28 Al EE3 2000 0.22 0.22 0.29 29 A2 ES4 2000 0.18 0.17 0.30 30~ ~ -- 0 1.26 1.16 0.30 Notes for Table IV:
1. Film made from a random ethylene-acrylic acid interpolymer containing about 9 wt.~ acrylic acid, having a melt flow value of about 3, and prepared at 3.3. MPa above and 15C above V
its respective two-phase transition zone.
2. Film made from a superior random ethylene-acrylic acid interpolymer containing about 9 wt.
acrylic acid, having a melt flow value of about 3, and prepared at 26.7 MPa above and 20C
above its respective two-phase transition zone.
3. Erucyl erucamide.
4. Erucyl stearamide.
5. See above for description of COF measurements.
This composition is not within the scope of this invention; data supplied for purpose of comparison.
o Experiment VI

. Additional data confirming the results of Experiment V was obtained by fabricating various interpolymers with various single amide additives into 30.5 cm layflat film by usual inflation techniques on a 3.81 cm Egan blown film unit at 204C plastic temperature. Both the superior random and the compositionally non-uniform interpolymers used contained 6.5 weight percent acrylic acid and had a melt flow value of 2.5 dg/min. However, the superior random interpolymer was prepared at 31.0 MPa and 15C
above its respective phase transition zone, while the non-uniform interpolymer was prepared below its respective phase transition zone. The results are presented in Table V.

33,218A-F -26-U E ~ ' ~ ~ ~ E
o ~ AC~ O u ~ ~

o C ~ C C
E t~ o o~,~, o ~o o o u~

A ~ ~ U U ~, u ~ ;
C ~ ~ .U--' c ~ C --~ ' ~ o E o o ~ C ~ ~ U
o O O O O O~ o .~ O.
~` c U ~ ~ I V~
E~ ", 3 ~ c .i o cO --I
hl U~ L~ ~ al cl v ~ ~ O
J ~ L~ ~ nu~
Ll 3 ~ L- . J O O
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C
L~ 0 v v~ ~ , e :1 . ni U .r~
E ~ o ~ ~ v~
al - ~ ~ alo . ~ c a~~ o O _~ ~`1 ~ N ~ E o~o E c-~
G ~: m ~: m ~: m ~ m o o c o ~ o .. L. ,~
U ~ al aJ--~ L- o N al o~
u ~ o ~ ~ ~ U E ~ c C al ~ o ~-al c ~ J ~ ~ al v ,~_~ O
L~ E-- E ~ , o, ~
O a ~ ~ ~ 0 ~ L~ ~ al _ ~ E ~ E ~ 3 c u al al 0 O~
a~ o _~ J o al ~ ~ C

Claims (5)

1. A composition comprising in intimate admixture (a) at least one copolymer of from 2 to 35 weight per-cent acrylic or methacrylic acid and 98 to 65 weight percent ethylene having a melt flow volume of from 0.01 to 50 dg/min; and being prepared by interpolymerization at a reactor temperature and pressure above its two-phase transition zone, and, (b) from 0.05 to 2 percent, by weight of the composi-tion, of at least one secondary fatty acid amide of the formula R5-CO-NH-R6, wherein R5 is a mono-olefinically unsaturated alkyl group having from 17 to 23 carbon atoms and R6 is a mono-olefini-cally unsaturated alkyl group having from 18 to 24 carbon atoms.

2. Composition of Claim 1 wherein the copolymer is prepared at a reactor temperature and pressure above or below its two-phase transition zone and R5 is a mono-olefinically unsaturated alkyl group having from 19 to 23 carbon atoms and R6 is a mono-olefini-cally unsaturated alkyl group having from 20 to 24 carbon atoms.

3. Composition of Claim 1 or 2 wherein from 5 to 95 percent of the carboxyl groups in the copolymer are neutralized with metal cations.

4. Composition of claim 3 wherein the metal cations are cations of zinc, sodium, magnesium, potassium, lithium, calcium or barium.

5. Composition of any one of Claims 1, 2 and 4 wherein the ethylene copolymer is prepared by polymerization at reactor pres-sure and temperature at least 26.7 above and 20°C above its two-phase transition zone, and wherein the copolymer has a ratio of adjacent polymerized polar monomer groups to the total polymerized polar monomer groups less than 0.44.