WO1991004853A1

WO1991004853A1 - Polymeric composition having enhanced surface energy and method for obtaining same

Info

Publication number: WO1991004853A1
Application number: PCT/US1990/005597
Authority: WO
Inventors: Eric S. Gardiner; John T. Geoghegan; Dale L. Haner
Original assignee: Arizona Chemical Company
Priority date: 1989-10-02
Filing date: 1990-10-02
Publication date: 1991-04-18
Also published as: KR920702288A; JPH05500677A; EP0494959A4; EP0494959A1

Abstract

A polymeric composition having enhanced surface energy and a method for obtaining the same, such method comprising blending from about 99.5 % to about 90.0 % by weight of the polymeric material with from about 0.5 % to about 10.0 % by weight of an amphiphile having the formula: RA(CHR2[CH2]nA1)mR1 where R and R1 are selected from the group consisting of the alkyl, aryl, alkylaryl, acyl and arylacyl derivatives of an aliphatic or aliphatic/aromatic mono-acid with a molecular weight of from about 200 to about 500 daltons, A and A1 are polar atoms or groups, R2 is selected from the group consisting of H, CH¿3? and C2H5, n is from 0 to 3 and m is from 2 to 20. A and A?1¿ are selected from the group consisting of O, S, -NR3- and carboxyl, with R3 selected from the group consisting of H, CH¿3? and C2H5. An adhesive tape prepared from the product of the method is also disclosed.

Description

POLYMERIC COMPOSITION HAVING ENHANCED SURFACE ENERGY AND METHOD FOR OBTAINING SAME

The present invention relates to low or medium density organic polymeric materials, particularly polyole- fins, having enhanced surface energy and to methods for obtaining the same. Low density polyethylene (LDPE) and other low and medium density polyolefins such as polypropylene, alpha- olefin modified polypropylene, polystyrene, TPX, i.e. poly(4- methylpentene-1) , and other organic polymeric mate¬ rials are used in high volume applications in the packaging industry in the form of injection molded parts, free ex¬ truded films and extrusion coatings on substrates such as paper, metal foils or non-woven fabrics. As such, it is often desirable to print or coat an exterior polymeric surface to enhance visual appeal, list ingredients, adver- tise, or protect the surface. There is also interest in using films of low and medium density polyolefins with acrylic based or other water-borne adhesives to produce adhesive tapes.

Because of the inherent low surface energy of these polymeric materials, the surface must be modified, that is made more polar, in order to accept most printing ink and coating or adhesive formulations. The current industry practice for surface modification of these materi¬ als is to oxidize the surface through flame or corona dis- charge treatment. Either of these treatments produces an acceptable surface, raising the surface energy from about 28 to about 42 dynes/cm². However, the effect is transient and surfaces that reside too long between treatment and printing or coating (i.e., greater than about four weeks) must be retreated for successful application.

In general, adhesive tapes of current technology employ MYLAR^R or other polyesters of high surface energy, rather than polyolefins, as film substrates for water-borne adhesives. Although these films are adequate for present uses, there exists a need for films with the strengths and costs of polyolefins combined with the high surface energies of polyesters.

It is, therefore, an object of the present inven- tion to provide a polymeric composition having enhanced surface energy.

It is another object of the present invention to provide low and medium density organic polymeric materials with increased surface energies which are stable for extend- ed time periods.

It is another object of the present invention to provide a method for producing a polymeric material having enhanced surface energy.

It is another object of the present invention to provide a composition for increasing the surface energy of low and medium density organic polymeric materials.

It is another object of the invention to provide high surface energy materials which are suitable for use as adhesive tape substrates. The present invention provides a method for en¬ hancing the surface energy of a surface of a low or medium density, low surface energy organic polymeric material. The method comprises blending from about 99.5% to about 90.0% by weight of the polymeric material with from about 0.5% to about 10.0% by weight of an a phiphile having the formula

where R and R¹ are selected from the group consisting of the alkyl, aryl, alkylaryl, acyl and arylacyl derivatives of an aliphatic or aliphatic/aromatic mono-acid with a molecular weight of from about 150 to about 500 daltons, R² is se¬ lected from the group consisting of H, CH₃ and C₂H₅, A and A¹ are polar atoms or groups, m is from 2 to 20 and n is from 0 to 3. Examples of polar atoms or groups that are useful as A and A¹ include, but are not restricted to, O, S, -NR³- or carboxyls. When A or A¹ is -NR³-, R³ is selected from the group consisting of H, CH₃ and C₂H₅. The value of n may be, but it is not necessarily, the same throughout the amphiphile. In preferred methods, the blending of the polymeric material with the amphiphile is accomplished by either melt blending, the blending of two solutions contain¬ ing the polymer and the amphiphile, blending in a high shear mixer or adding the amphiphile as a solid or liquid to the polymeric material during extrusion. Alternatively, the amphiphile could be added to the polymer during work-up immediately after polymerization.

Examples of alkyl, aryl, alkylaryl, acyl and arylacyl derivatives of an aliphatic or aliphatic/aromatic mono-acid with molecular weights of from about 150 to about 500 daltons include, but are not restricted to, alkylben- zenes, aliphatic alcohols, acyl derivatives of saturated fatty acids having carbon atom chain lengths of from about 10 to 26 atoms, soya and tall oil fatty acids, alkylbenzoic acids and tall oil, wood and gum rosin acids.

The present invention also provides for a low or medium density polyolefinic composition with a high surface energy. The high surface energy does not decrease over a period of months. This is in contrast to corona discharge, as normally carried out, which produces a metastable oxi¬ dized high energy surface. After about 3 to 4 weeks the surface reverts to a lower surface energy. Consequently, printing and adhesive qualities rapidly deteriorate on storage. The composition is comprised of from about 99.5% to about 90.0% of a low or medium density, low surface energy polyolefin and from about 0.5% to about 10.0% by weight of the amphiphile described above. In a preferred composition R=R¹, R² is hydrogen, A = A¹ = oxygen, m is 9 and n = 1 and the composition is comprised of about 98% of the polyolefin and about 2% of the amphiphile. In another preferred composition R = R¹, R² is hydrogen, A = A¹ = -NR³-, R³ = hydrogen, m is 14, and n = 1 and the composition is comprised of about 98% of the polyolefin and about 2% of the amphiphile. In yet another preferred composition, R = R¹, R² is hydrogen, A = A¹ = carboxyl, m is 7, n = 5 and the composition is comprised of about 98% of the polyolefin and about 2% of the amphiphile.

The present invention also provides for a composi¬ tion for increasing the surface energy of a low or medium density, low surface energy organic polymeric material whereby the composition is added to the polymeric material. The composition has the formula:

where the composition is the amphiphile described previous¬ ly. The present invention also provides for an adhe¬ sive tape comprising a low or medium density polyolefinic composition comprising from about 99.5% to about 90.0% by weight of a low or medium density, low surface energy pol¬ yolefin and from about 0.5% to about 10.0% of an amphiphile as previously described, and a water-dispersed adhesive. By use of the word "tape" is meant strips, film, sheets and other similar geometries.

When the present invention is used to produce adhesive tapes, the adhesive can be any water-based solution or dispersion. For example, acrylic adhesives work quite well. Best results are achieved with adhesives that can act as hydrogen donors for hydrogen bonding.

The amphiphile disclosed in the present invention has a central hydrophilic component and two lipophilic components (represented by R and R¹ in the above formula) attached to either end of the central component. Without being bound by the theory, it is believed that the two lipophilic regions are most compatible with the organic polymeric material. Therefore, it is thought that the amphiphile is anchored in the polymeric material by those lipophilic portions. The hydrophilic portion comprising alternating organic and polar groups, in the middle of the amphiphile, is less compatible with the organic polymeric material. Therefore, it is thought that the hydrophilic segment resides at the surface of the polymeric material. It is believed that this hydrophilic segment raises the surface energy of the polymeric material. Since the lipo- philic segment of the amphiphile is anchored in the polymer¬ ic material, the surface energy of the polymeric material is increased on a more permanent basis than is possible using previous techniques. The presence of a nitrogen in the central compo¬ nent provides an additional advantage over other polar components. The resulting amphiphile acts as an active hydrogen donor in addition to accepting hydrogen bonding. Therefore, it is possible to tailor the amphiphile for a specific use requiring hydrogen donation from a particular surface coating.

The amphiphile is generally formed by the reaction of, for example, polyglycols, polysulfides, polyimines or polyester diols with hydrophobes such as fatty acids, rosin acids, alkylphenols or aryl or aliphatic alcohols. The chain length of the hydrophilic segment, polyethylene glycol for example, varies from 2-20 units (where a unit is com¬ posed of 1, 2, 3 or 4 carbon atoms and one polar atom or group, for example, one oxygen, sulfur or nitrogen atom or carboxyl group) with a preferred length of about 10 units. The hydrophobes generally have chain lengths of from about 10 to about 26 atoms. The aromatic, aliphatic or mixed alcohols have molecular weights from about 150 to about 500 daltons. There is a preferable limitation to the length of the hydrophilic portion of the amphiphile. At lengths of 2 units the addition of the amphiphile to the polymeric material does not significantly increase the surface energy of the material. At chain lengths of above 20 units, al- though there may be initial improvement in surface energy, the amphiphile leaches easily into aqueous liquids. This results in an eventual lowering of the surface energy of the polymeric material and consequently a loss in printabil- ity or suitability as a substrate for adhesive tape. In general, the optimum chain length is 10 units, although specific product usage may require greater or lesser chain lengths. The increase in surface energy of the polymeric material is measured by the contact angle of water on the surface of the polymeric material. This contact angle is related to printability and suitability as a substrate for adhesive tape. Surface energy is also related to surface polarity and wettability and is extremely difficult to measure directly. Consequently, surface energy is normally measured indirectly by using liquids of known surface ener¬ gy. When a match occurs, the liquid spreads rapidly over the surface. The surface energy of the surface is then equal to the surface energy of the liquid. More simply, the contact angle of a single substance, for example water, can be measured and the surface energy estimated. Generally, a required contact angle can be determined for the property desired. In the case of printing with normal inks, the water contact angle should be between about 60° to about 70°. In the case of acrylic based adhesives (applied as an aqueous dispersion) , the water contact angle should be between about 50° and about 70°. Untreated low density polyethylene, for example, shows a contact angle of 91°. The addition of between 0.5 and 10.0% of the amphiphile to the polymeric material results in contact angles between 70° and 30°.

In addition, it is preferable that the amphiphile concentration not exceed 10% by weight. At amphiphile addition amounts of greater than 10% there is an indica¬ tion of significant phase separation between the amphiphile and the polymeric material. Once phase separation occurs, there is no improvement in printability or adhesion and little change in the surface energy.

The organic polymeric material is not restricted to low density polyethylene. Other low and medium density polyolefins such as polypropylene, alpha-olefin modified polyethylene and polypropylene, polystyrene, and TPX are also suitable for treatment with the amphiphile for raising their surface energies. These other polyolefins are blended with the amphiphile in like manner as polyethylene. In order to provide a more complete understanding of the invention, the following examples are offered by way of illustration and not by way of limitation.

EXAMPLE I A series of amphiphiles were prepared by the esterification of carboxylic acids. These materials were prepared by reacting a polyethylene glycol of the indicated molecular weight with a slight excess over two equivalent weights of the chosen acids under the indicated conditions shown in Table I. The amphiphiles were produced in a reac¬ tor arranged for nitrogen blanketing and stirring with an exit condenser to condense removed water. An acidic cata¬ lyst was employed for convenience. Table I summarizes reaction conditions and the amphiphiles produced.

TABLE I SYNTHESIS OF AMPHIPHILE A-I

REACTION

CARBOXYLIC ACID PEG* CATALYST CONDITIONS AMPHIPHILE PRODUCED

Type Wt. q. Mol. Wt. Wt. q. Type Wt. . Hours T. C # Acid No. Gardner Yield %¹¹ State

TORA^J 520 150 112 H₃P0₄ 0.4 29 280 A 11 7 89 Viscous TORA^] 520 165 150 H₃P0₂ 0.6 32 260 B 12 6 92 viscous

Liquid

TORA^J 520 400 300 H₃P0₂ 0.6 29 260 11 94 Viscous

Liquid

WOOD'¹ 543 400 300 H₂S0₄ 0.2 39 270 D 11 88 Viscous ROSIN Liquid GUM³ 506 400 300 H₃P0₂ 0.6 25 270 12 93 Viscous ROSIN Liquid

DIST.^ 482 400 300 H₃P0₂ 0.6 28 270 90 Viscous TORA Liquid STEARIC⁵ 350 400 249 PTSA⁹ 0.5 20 220 ,10 98 Waxy

Solid

PALMITIC⁶ 406 400 300 H₃P0₂ 0.6 22 220 H ,10 98 Waxy

Solid

TOFA 208 400 249 H₃P0₄ 0.3 22 220 12 98 Liquid

TABLE I (continued) NOTES FOR TABLE I

1. Acintol R Types S Tall Oil Rosin, Arizona Chemical Company

2. W W Wood Rosin, Hercules

3. Gum Rosin, Brazil

4. Beviros 95 Distilled Tall Oil Rosin, Arizona Chemical Company

5. Aldrich Chemical Co., 95% Pure

6. Aldrich Chemical Co., 99% Pure

7. Acintol EPG Tall Oil Fatty Acid, Arizona Chemical Company

8. Linear Polyethylene Glycols of Carbowax Type Produced by Union Carbide at Various Molecular Weights

9. Para-toluene sulfonic acid

10. Molten Color

11. As % of Theory

EXAMPLE II A glass reactor, fitted with a condenser to col¬ lect condensate, a stirrer and arranged for nitrogen blan¬ keting, was charged with 200 parts of branched 18 carbon fatty acids (Sylfat™, Arizona Chemical Co., D-1 fatty acid, acid number 178) , lOOg of polyethylene glycol (average molecular weight of 400, an average of 9.1 moles of ethyl¬ ene oxide per chain) and 0.5g of phosphorus acid. The reactor was blanketed with nitrogen, stirred, and the tem- perature raised to 200°C and held at that temperature for seven hours. After completion of the reaction, the mixture was stripped under vacuum to remove the excess unreacted fatty acid. The resulting amphiphile, J, was produced in 82.5% yield, with a Gardner color of 5 and an acid number of 6.3. This amphiphile was a mobile liquid at room temper¬ ature.

EXAMPLE III The general procedure of Example II was followed to produce amphiphile K. In this case, 40g of nonylphenol ethylene oxide condensate (Igepal 710, GAF Corp., 10-11 mole of ethylene oxide condensate) was reacted with 21g of tall oil rosin (AN 175) for 29 hours in the presence of 21mg of hypophosphorus acid catalyst at 270°C. After completion of the reaction, the amphiphile K was analyzed by gel phase chromatography which indicated a purity of 89% with the major impurity excess rosin (about 10%) . The amphiphile K was a viscous oil at room temperature with a Gardner color of 4 and an acid number of 15.

EXAMPLE IV Amphiphile L was prepared as follows in a glass reactor fitted with stirrer, heater, nitrogen blanketing, and an exit condenser. Twenty grams of polyethylene glycol (molecular weight of 400) 18.6g of methyl decanoate and 0.2g of para-toluene sulfonic acid were charged to the reactor. The mixture was stirred and heated to 130"C for 1 hour and then 160°C for 1 1/2 hours. The resulting amphi¬ phile was analyzed by gel phase chromatography and deter- mined to be about 98% pure in 100% yield. The amphiphile L had a Gardner color of 3, an acid number of 2 and was a mobile liquid at room temperature.

EXAMPLE V A 251g sample of Permapol^® P-3 Polyol (Thiokol) , a mixed hydroxyl terminated oxygen-sulfur ether having a typical structure of -CH₂CH₂S CH₂CH₂0 CH CH₂S CH₂CH₂0 CH₂0 CH₂CH₂S CH₂ CH₂0-

I

CH₃ and a molecular weight of 500, was reacted with 350g of tall oil rosin acid in the presence of 0.6g of 50% aqueous hypo- phosphous acid and was heated at 270°C for four hours. The product, amphiphile M, was obtained in essentially quantita¬ tive yield as a viscous amber oil with an acid number of 12.4.

EXAMPLE VI A sodium dispersion was prepared in a Morton flask with 9.2 g of sodium dispersed in 250 ml of distilled tet- rahydrofuran and mixed at 20°C. With continued stirring, a mixture of 22.5 g of polyethylene glycol 400 and 30.1 g of l- romohexadecane was added to the reaction mixture and the mi.':ure was raised to reflux. After 48 hours, the sodium was removed by filtration and the tetrahydrofuran was evapo¬ rated from the reaction mixture. The crude amphiphile, bis- hexadecyl polyethylene glycol ether, was dissolved in ethyl ether. The ether solution was washed with water and then purified on a silica gel column to produce the purified amphiphile N. Amphiphile N was obtained as a viscous, pale yellow oil.

EXAMPLE VII Preparation of a hicrh surface energy polyolefin. An organic polymeric composition with a high surface energy was prepared as follows. A low density polyethylene (Alathon^®, with 0.92-0.94 specific gravity, characterized by a melt index of 3.5-4.5 condition E ASTM Standard, produced by the DuPont Company; Tenite^® 1924, with 0.92-0.94 specific gravity, characterized by a melt index of 3.5-4.5 condition E ASTM Standard, produced by Eastman Kodak; or Dow Resin 5004, with 0.92-0.94 specific gravity, characterized by a melt index of 3.5-4.5 condition E ASTM Standard, produced by Dow Chemical Company) and the selected amphiphiles at various levels were combined together in melt form, by mixing in an extruder or by mixing in a high shear mixer. The means of compounding was not important so long as intimate mixing was accomplished. After compounding, the polymeric product was extruded as a film or was extruded as a film directly onto glass. The surface energy of the film was measured by determination of the contact angle. Table II details polymeric composition produced and the contact angles determined.

Amphiphile C was also master batched in an extrud- er. Polyethylene resin and the amphiphile were combined in an extruder and then extruded. The extrudate was chopped to make normal resin pellets. The master batch was then ex¬ truded onto metal, paper and as a free film. Contact angles determined on those substrates confirm the contact angles shown in Table II. These substrates have also been success¬ fully printed in a plant trial seven weeks after a coated board was produced. TABLE II

WATER⁵ CONTACT ANGLES OF LDPE COMPOSITIONS

WATER CONTACT ANGLE <^b) 2% BY WEIGHT 5% BY WEIGHT 10% BY WEIGHT

91

75

82 75

71 57 58 56

65 63 49 57 30 36 31 25 63 16 62 53 74 60 69 70

81 63

TABLE II. continued

(a) Distilled water with 0.01% by weight aniline blue added for contrast

(b) Decreasing contact angle equals increased surface energy.

EXAMPLE VIII Amphiphile C from Example I was composited with the polyolefin Alathon 1640 (DuPont) at 1, 2 and 5 weight percent as in Example VII. Water contact angles were deter¬ mined and the results are listed in Table III. As may be seen in Table III, measurement of the contact angle is less reproducible as the concentration of the amphiphile is increased. This we speculate is related to the limited solubility of the amphiphile in the polyolefin.

TABLE III

Weight Percent of Water Contact Amphiphile Angle

1 81 + 4 2 71 ± 12 5 57 + 12

EXAMPLE IX Synthesis of an Amphiphilic Amide:

Tall oil rosin was first converted to the rosin acid chloride which was reacted with the polyimine in a pyridine solution. The reaction mixture was maintained at between 0°C to 2°C for 2 hours and then slowly warmed to room temperature over 1 hour. The mixture was held at room temperature for 30 minutes. The product was coagulated by pouring the reaction mixture into a large excess of hexanes. The coagulated product was washed with hexane and redis- solved in methanol. The methanol solution was transferred to another vessel and the methanol was removed by evapora¬ tion. Table IV details the amphiphiles produced. TABLE IV SYNTHESIS OF AMPHIPHILE 0

Carboxylic Acid Polyimine Diamine Amphiphile

Gardner Tvpe Wt(α) Mol. Wt. Type ^b Wt( ) Mol. Wt. # Color Yield

TORA 25 302 PEI 24.7 600 0 >18 70%^c

(a) TORA = tall oil resin acid;

(b) PEI = polyethylene imine.

(c) As determined by infrared and NMR Spectroscopy.

EXAMPLE X

Synthesis of Polyolefins with High Surface Energy:

Low or medium density polyolefins were combined with selected amphiphiles, as shown in Table V, as melts or by solvent blending. The means of compounding was not important so long as intimate mixing was accomplished. After compounding, the polymeric product was extruded as a film or was extruded as a film directly onto glass. The surface energy of the film was measured by determination of the contact angle of water. Table V details polymeric compositions produced and the contact angles determined.

TABLE V WATER^a CONTACT ANGLES OF POLYOLEFIN COMPOSITIONS

Amphiphile Polyolefin" Water Contact Angle⁰

2%^d 5% None PS 77

O PS 70 70

(a) Distilled water with 0.01% by weight aniline blue added for contrast.

(b) PS = polystyrene. (c) Decreasing contact angle equals increasing surface energy.

(d) Amphiphile, by weight, added to polyolefin. EXAMPLE XI

Synthesis of Amphiphilic Polyesters :

To prevent redistribution and transesterification during esterification, tall oil rosin was first converted to the rosin acid chloride . The acid chloride was reacted with a l inear polyester diol , as shown in Table VI , in toluene at 90 ° C, with pyridine as an HC1 scavenger . The product was decanted from over precipitated pyridinium hydrochloride , and the solvent removed by distillation . The product had the characteristics indicated in Table VI .

TABLE VI SYNTHESIS OF AMPHIPHILE P Carboxylic Acid Polyester Diol Amphiphile

Gardner Tvpe^a Wt(g) Tvpe^b Wtfg) Mol. Wt. # Acid No.^c Color Yield TORA 50 PCL 44 630-912 P 25.6 >18 86%

(a) TORA = Tall Oil Rosin Acid;

(b) PCL = polycaprolactone;

(c) mg KOH/g amphiphile

EXAMPLE XII Synthesis of Polyolefins With High Surface Energy

Low or medium density polyolefins were combined with selected amphiphiles, as shown in Table VII, as melts, by mixing in an extruder or by solvent blending. The means of compounding was not important so long as intimate mixing was accomplished. After compounding, the polymeric product was extruded as a film or was extruded as a film directly onto glass. The surface energy of the film was measured by determination of the contact angle of water. Table VII details polymeric compositions produced and contact angles determined.

TABLE VII WATER^a CONTACT ANGLES OF POLYOLEFIN COMPOSITIONS Amphiphile Polyolefin^b Water Contact Angle^c l%^d 2%

None LDPE 91

None PP 82

P PP 70 65 P LDPE 78 75

(a) Distilled water with 0.01% by weight aniline blue added for contrast.

(b) LDPE = low density polyethylene; PP = polypro¬ pylene (c) Decreasing contact angle equals increasing sur¬ face, (d) Amphiphile, by weight, added to polyolefin.

EXAMPLE XIII

Preparation of Amphiphile 0: Amphiphile Q was prepared by the esterification of tall oil rosin acid (Acinol R Type S Tall Oil Rosin, Arizona

Chemical Company) with polyethylene glycol (Carbowax type,

Union Carbide, molecular weight of 400) . Slightly over two equivalent weights of the polyethylene glycol were reacted with the tall oil rosins, in the presence of a phosphoric acid catalyst, at 260°C for 29 hours. The reaction was carried out under a nitrogen blanket with stirring and an exit condenser to condense removed water. The resulting amphiphile Q had an acid number of 11 mg KOH/g of product and a Gardner color of 7. The amphiphile was a viscous liquid produced in 94% yield. EXAMPLE XIV

Preparation of Film:

Amphiphile Q of Example XIII was combined with low density polyethylene (LDPE) in an extruder, giving a film with 3% by weight of amphiphile. In general, the means of compounding the film was not important so long as intimate mixing was accomplished. The film was extruded onto a paper substrate. A water-dispersed acrylic latex adhesive formu¬ lation was roll coated onto the exposed LDPE surface, air dried for 20 minutes at room temperature and then fused by heating for 3 minutes at 100°C.

EXAMPLE XV The adhesive coated film of Example XIV was cut into 1 inch by 5 inch strips and adhered to stainless steel plates. Adhesion was then tested as 180° peel strength with a separation rate of 12 inches/minute. At short dwell times (dwell time is the contact time of adhesive to steel between application and testing) , between 30 minutes and 1 hour, the composites gave good peel strength (see Table VIII) with failure occurring at the adhesive/steel interface. With longer dwell times, greater than 3 hours, the composite failed within the paper substrate. In all cases, there was no failure at the LDPE/acrylic interface.

TABLE VIII

Adhesive Dwell Time (hr) 180° Peel Strength (oz/in)^a Avery Chemical ^b 0.5 60.5

ROBOND^c 1.0 96.9

ROBOND >3 (d)

(a) Film thicknesses for both coatings were 1 mill (0.001 inch. (b) A proprietary acrylic supplied by Avery Chemical, tackified with 30% by weight AQUATAC 6085 (Arizona Chemical) . (c) ROBOND PS-95, formerly Rohm and Haas E2395 supplied by Rohm and Haas.

(d) Failure occurred within paper substrate; no peel strength recorded. From the foregoing, it may be seen that the addi¬ tion of the amphiphile to a low density polyolefin greatly increases the surface energy of the low density polyolefin. Since printing and adhesion are most efficient at water contact angles of less than 70°, the addition of the amphi- phile greatly increases the usability of the polymeric material. The example also illustrates that the surface energy of the polymeric material can be raised to the de¬ sired level by the addition of the appropriate amount of amphiphile to the polymeric material. This improvement in the surface energy of the polymeric material extends beyond low density polyethylene to a wide range of low and medium density polyolefins, including polypropylene, alpha-olefin modified polypropyl¬ ene and polyethylene, polystyrene and TPX. In addition, the surface energy is improved for a period of time greater than 8 months as compared to prior treatments which were effec¬ tive only for a period of four weeks or less. Therefore, the present invention provides for a means of increasing the surface energy of low and medium density organic polymeric materials for relatively long periods of time.

It is also shown that an effective adhesive tape is produced from the high surface energy polyolefins of the present invention. When subjected to tests for peel strength, the bond fails in the substrate and not at the polymer surface.

Various of the features of the invention which are believed to be new are set forth in the appended claims.

Claims

THE CLAIMS :

1. A low or medium density polyolefinic composi¬ tion comprised of: from about 99.5% to about 90.0% by weight of a low or medium density, low surface energy polyolefin; and from about 0.5% to about 10.0% by weight of an amphiphile having the formula:

RA(CHR²[CH₂]_nA¹)_mR¹ where R and R¹ are selected from the group consisting of the alkyl, aryl, alkylaryl, acyl and arylacyl derivatives of an aliphatic or aliphatic/aromatic mono-acid with a molecular weight of from about 150 to about 500 daltons, A and A¹ are selected from the group consisting of 0, S, -NR³- or car¬ boxyl groups and R³ is selected from the group consisting of H, CH₃ and C₂H₅, R² is selected from the group consisting of H, CH₃ and C₂H₅, n is from 0 to 3 and m is from 2 to 20.

2. The composition of Claim 1 wherein R and R¹ are identical, R² is hydrogen and A and A¹ are oxygen.

3. The composition of Claim 1 wherein R and R¹ are identical, R² is hydrogen and A and A¹ are selected from the group consisting of oxygen and sulfur.

4. The composition of Claim 1 wherein R and R¹ are identical, R² is hydrogen and A and A¹ are -NH-.

5. The composition of Claim 1 wherein R and R¹ are identical, R² is hydrogen and A and A¹ are carboxyls.

6. The composition of Claim 1, 2, 3, 4 or 5 wherein said polyolefin is selected from the group consist¬ ing of polyethylene, polypropylene, alpha-olefin modified polypropylene, polystyrene and poly(4-methylpentene-l) .

7. The composition of Claim 1, 2, 3, 4 or 5 wherein m is from 4 to 12.

8. The composition of Claim 1, 2, 3 , 4 or 5 wherein m is 9.

9. The composition of Claim 1, 2, 3, 4 or 5 comprised of: between about 99% and about 95% of said polyole¬ fin; and between about 1% and about 5% of said amphiphile.

10. A composition for increasing the surface energy of a low or medium density, low surface energy organ¬ ic polymeric material, said composition having the formula:

RA(CHR²[CH₂]_nA¹)_mR¹ where R and R¹ are selected from the group consisting of the alkyl, aryl, alkylaryl, acyl and arylacyl derivatives of an aliphatic or aliphatic/aromatic mono-acid with a molecular weight of from about 150 to about 500 daltons. A and A¹ are selected from the group consisting of O, S, -NR³- and carbo- nyl and R³ is selected from the group consisting of H, CH₃ and C₂H₅, R² is selected from the group consisting of H, CH₃ and C₂H₅, n is from 0 to 3 and m is from 2 to 20, whereby said composition is blended with the organic polymeric material to form a polymeric material with an increased surface energy.

11. The composition of Claim 10 wherein R and R¹ are identical, R² is hydrogen and A and A¹ are oxygen.

12. The composition of Claim 10 wherein R and R¹ are identical, R² is hydrogen and A and A¹ are selected from the group consisting of oxygen and sulfur.

13. The composition of Claim 10 wherein R and R¹ are identical, R² is hydrogen and A and A¹ are -NH-.

14. The composition of Claim 10 wherein R and R¹ are identical, R² is hydrogen and A and A¹ are carboxyls.

15. The composition of Claim 10, 11, 12, 13 or 14 wherein m is from 4 to 12.

16. The composition of Claim 10, 11, 12, 13 or 14 wherein m is 9.

17. An adhesive tape comprising:

A low or medium density polyolefinic composition comprised of: from about 99.5% to about 90.0% by weight of a low or medium density, low surface energy pol¬ yolefin; and from about 0.5% to about 10.0% by weight of an amphiphile having the formula:

RA(CHR²[CH₂] _nA^λ)^R¹ where R and R¹ are selected from the group con¬ sisting of the alkyl, aryl, alkylaryl, acyl and arylacyl derivatives of an aliphatic or aliphatic/aromatic mono-acid with a molecular weight of from about 200 to about 500 daltons, A and A¹ are selected from the group consisting of

O, -NR³-, carboxyl and S, R² and R³ are selected from the group consisting of H, CH₃ and C₂H₅, n is from 0 to 3 and m is from 2 to 20; and a water dispersed-adhesive.

18. The adhesive tape of Claim 17 wherein R and R¹ are identical, R² is hydrogen and A and A¹ are oxygen.

19. The adhesive tape of Claim 17 wherein R and R¹ are identical, R² is hydrogen and A and A¹ are selected from the group consisting of oxygen and sulfur.

20. The adhesive tape of Claim 17 wherein R and R¹ are identical, R² is hydrogen and A and A¹ are NH.

21. The adhesive tape of Claim 17 wherein R and R¹ are identical, R² is hydrogen and A and A¹ are carboxyls.

22. The adhesive tape of Claim 17, 18, 19, 20 or 21 wherein said polyolefin is selected from the group con¬ sisting of polyethylene, polypropylene, alpha-olefin modi¬ fied polypropylene, polystyrene and poly(4-methylpentene- 1) .

23. The adhesive tape of Claim 17, 18, 19, 20 or 21 wherein m is from 4 to 12.

24. The adhesive tape of Claim 17, 18, 19, 20 or 21 comprised of: between about 99% and about 95% of said polyole¬ fin; and between about 1% and about 5% of said amphiphile.

25. The adhesive tape of Claim 17, 18, 19, 20 or 21 wherein the adhesive is an acrylic adhesive.

26. A method for increasing the surface energy of a low or medium density, low surface energy organic polymer¬ ic material comprising blending from about 99.5% to about 90.0% by weight of said polymeric material with from about 0.5% to about 10.0% by weight of an amphiphile having the formula

RA(CHR²[CH₂]_nA¹)_mR¹ where R and R¹ are selected from the group consisting of the alkyl, aryl, alkylaryl, acyl and arylacyl derivatives of an alphatic or aliphatic/aromatic mono-acid with a molecular weight of from about 150 to about 500 daltons, R² is selected from the group consisting of H, CH₃ and C₂H₅, A and A¹ are selected from the group consisting of 0, S, -NR³- or carboxyl groups, R³ is selected from the group consisting of H, CH₃ and C₂H₅, m is from 2 to 20 and n is from 0 to 3.

27. The method of Claim 26 wherein R and R¹ are identical, R² is hydrogen and A and A¹ are oxygen.

28. The method of Claim 26 wherein R and R¹ are identical, R² is hydrogen and A and A¹ are selected from the group consisting of oxygen and sulfur.

29. The method of Claim 26 wherein R and R¹ are identical, R² is hydrogen and A and A¹ are - NH -.

30. The method of Claim 26 wherein R and R¹ are identical, R² is hydrogen and A and A¹ are carboxyls.

31. The method of Claims 26, 27, 28, 29 or 30 wherein said polymeric material is selected from the group consisting of polyethylene, polypropylene, alpha-olefin modified polypropylene, polystyrene and poly(4-methylpene- tene-1) .

32. The method of Claims 26, 27, 28, 29 or 30 wherein is from 4 to 12.

33. The method of Claims 26, 27, 28, 29 or 30 wherein m is 9.

34. The method of Claims 26, 27, 28, 29 or 30 wherein there is between about 99% and about 95% of said organic polymeric material and there is between about 1% and about 5% of said amphiphile.