Water borne polyolefin dispersion coatings, and methods of making

Abstract

The present invention provides aqueous polyolefin dispersion compositions for use in metal coatings, such as can coatings, comprising one or more polyolefin base polymer, one or more at least partially neutralized olefinic stabilizing agent having an acid number (AN) of from 80 to 250, preferably, a polyolefin stabilizing agent, such as an olefin-carboxylic acid copolymer or a blend of two such polymers, an optional coupling agent having an acid number (AN) of from 10 to 70 and a melt index of from 500 to 5,000,000 grams of polymer melt passing in 10 minutes through a heated syringe or cylinder at 190 C. with a plunger loaded with 2.16 kg, preferably, a polymer, and a hindered phenolic antioxidant containing an ester linkage dispersed in the polyolefin dispersion composition. The hindered phenolic antioxidant containing an ester linkage can be masterbatched with a polyolefin base polymer, polyolefin stabilizing agent or a coupling agent which is a polymer, melt mixed with the remaining polyolefin composition and then dispersed with aqueous media and a neutralizing agent to form the aqueous dispersion.

Claims

1. A coating comprising a substrate having thereon one or more layers or films of a polyolefin dispersion composition comprising: one or more polyolefin base polymers chosen from a polyolefin, a carboxylic acid functional polyolefin and a carboxylate functional polyolefin, from 1 to 40 wt. %, based on the total solids of the polyolefin dispersion composition, of one or more olefinic stabilizing agents having an acid number (AN) of from 80 to 250, from 0 to 50 wt. %, based on the total solids of the polyolefin dispersion composition, of one or more coupling agents having an acid number (AN) of from 10 to 70 and a having a melt index of from 500 to 5,000,000 grams of polymer melt passing in 10 minutes through a heated syringe or cylinder at 190 C. with a plunger loaded with 2.16 kg; and, dispersed in at least one of the one or more polyolefin base polymers, the one or more olefinic stabilizing agents which are polymers, or the one or more coupling agents which are polymers, at least one hindered phenolic antioxidant containing an ester linkage, wherein when having a thickness of 10 microns, the coating exhibits a methyl ethyl ketone double rub resistance of 100 double rubs or more until the coating is cut through and the substrate becomes visible in any area according to ASTM D 5402-06, Method 3 (2011), using bleached cheese cloth (Grade 50) having 2824 threads per 2.54 cm2.54 cm square and a 906 g (32 ounce) ball peen hammer, wherein the cloth is fastened with a wire to the flat end of the hammer and rubbed against the coating back and forth across the coating, the cloth being re-dipped into MEK every 25 double rubs.

2. The coating as claimed in claim 1, wherein the phenolic antioxidant containing an ester linkage comprises at least one hydroxyphenylpropionic acid ester or a combination thereof with one or more second antioxidants.

3. The coating as claimed in claim 2, wherein the phenolic antioxidant containing an ester linkage is benzenepropanoic acid, 3-(1,1-dimethylethyl)--[3-(1,1-dimethylethyl)-4-hydroxyphenyl]-4-hydroxy--methyl-1,1-(1,2-ethanediyl) ester (CAS Registry No. 32509-66-3).

4. The coating as claimed in claim 1, wherein the total amount of hindered phenolic antioxidant containing an ester linkage ranges from 200 ppm to 10,000 ppm of total polyolefin dispersion composition solids.

5. The coating as claimed in claim 1, wherein the amount of the one or more olefinic stabilizing agents comprises an olefin-carboxylic acid copolymer or a blend of two such polymers.

6. The coating as claimed in claim 1, wherein the coating comprises from 2 to 30 wt. %, based on the total solids of the polyolefin dispersion composition, of the one or more coupling agents.

7. The coating as claimed in claim 1, wherein the one or more coupling agents is a maleic anhydride grafted polyolefin.

8. The coating as claimed in claim 1, wherein the one or more polyolefin base polymers comprises polyethylene, polypropylene, poly(alpha-olefin) copolymers, poly(alpha-olefin) terpolymers, or blends of any of these.

9. The coating as claimed in claim 1, wherein the substrate is a metal container, lid or closure for food or beverage.

10. A method of making a polyolefin dispersion composition for making the coating as claimed in claim 1 comprising: (i) melt blending the hindered phenolic antioxidant containing an ester linkage, the one or more polyolefin base polymers, the one or more olefinic stabilizing agents and the one or more coupling agents, if any, or (ii) (a) melt blending the polyolefin base polymer, any coupling agent, and the olefinic stabilizing agent and (b), separately, melt blending the hindered phenolic antioxidant in any of a one or more polyolefin base polymers, one or more olefinic stabilizing agents, or one or more coupling agents to form an antioxidant dispersion; followed by dispersing the melt of (i) or a melt of both (ii) (a) and (b) in water along with a sufficient amount of one or more volatile base to neutralize from 50 to 300% of the carboxylic acid groups in the one or more polyolefin base polymers, the one or more olefinic stabilizing agents, and the one or more coupling agents to form the polyolefin dispersion composition.

11. An aqueous polyolefin dispersion composition comprising, as the dispersed phase, particles comprising: one or more polyolefin base polymers chosen from a polyolefin, a carboxylic acid functional polyolefin and a carboxylate functional polyolefin; from 1 to 40 wt. % based on the total solids of the aqueous polyolefin dispersion composition, of one or more olefinic stabilizing agents having an acid number (AN) of from 80 to 250; from 0 to 50 wt. %, based on the total solids of the aqueous polyolefin dispersion composition, of one or more coupling agents having an acid number (AN) of from 10 to 70 and a having a melt index of from 500 to 5,000,000 grams of polymer melt passing in 10 minutes through a heated syringe or cylinder at 190 C. with a plunger loaded with 2.16 kg; and, dispersed in at least one of the one or more olefinic stabilizing agents, or the one or more coupling agents, at least one hindered phenolic antioxidant containing an ester linkage, wherein the phenolic antioxidant containing an ester linkage is benzenepropanoic acid, 3-(1,1-dimethylethyl)--[3-(1,1-dimethylethyl)-4-hydroxyphenyl]-4-hydroxy--methyl-1,1-(1,2-ethanediyl) ester (CAS Registry No. 32509-66-3).

12. The aqueous polyolefin dispersion composition as claimed in claim 11, wherein the total amount of hindered phenolic antioxidant containing an ester linkage ranges from 200 ppm to 10,000 ppm of total aqueous polyolefin dispersion solids.

13. The aqueous polyolefin dispersion composition as claimed in claim 11, wherein the one or more olefinic stabilizing agents comprises an olefin-carboxylic acid copolymer or a blend of two such polymers.

14. The aqueous polyolefin dispersion composition as claimed in claim 11, wherein the dispersion comprises from 2 to 30 wt. %, based on the total solids of the aqueous polyolefin dispersion composition, of the one or more coupling agents.

15. The aqueous polyolefin dispersion composition as claimed in claim 11, wherein the one or more coupling agents is a maleic anhydride grafted polyolefin.

16. The aqueous polyolefin dispersion composition as claimed in claim 11, wherein the one or more polyolefin base polymers comprises polyethylene, polypropylene, poly(alpha-olefin) copolymers, poly(alpha-olefin) terpolymers, or blends of any of these.

17. A coating comprising a substrate having thereon one or more layers or films formed by: applying the aqueous polyolefin dispersion composition of claim 11 to the substrate to form one or more coating layers; and drying the one or more coating layers to form the one or more layers or films.

Description

EXAMPLES

(1) The Examples that follow illustrate the present invention. Unless otherwise stated, in all of the Examples that follow, temperature is room temperature and pressure is atmospheric pressure.

(2) TABLE-US-00001 TABLE 1 Raw Materials for Polyolefin Dispersions Trade Name Supplier Description/Chemical structure Butyl CELLOSOLVE Dow.sup.2 Ethylene glycol mono-butyl ether n-butanol Dow.sup.2 n-butyl alcohol Irganox 1010 BASF.sup.1 Pentaerythritol tetrakis(3-(3,5-di-tert- butyl-4-hydroxyphenyl)propionate) (CAS # 6683-19-8) Irganox 3114 BASF.sup.1 1,3,5-Tris[4-hydroxy-3,5-bis(2- methyl-2-propanyl)benzyl]-1,3,5- triazinane-2,4,6-trione (CAS #27676-62-6) Irganox 1330 BASF.sup.1 1,3,5-Trimethyl-2,4,6-tris(3,5-di-tert- butyl-4-hydroxybenzyl)benzene (CAS # 1709-70-2) Hostanox O3 Clariant.sup.1 benzenepropanoic acid, 3-(1,1- dimethylethyl)--[3-(1,1- dimethylethyl)-4-hydroxyphenyl]-4- hydroxy--methyl-1,1-(1,2- ethanediyl) ester (CAS #32509-66-3) .sup.1Leverkusen, DE; .sup.2Midland, MI.

(3) TABLE-US-00002 TABLE 1A Raw Materials Melting Point Melt Density Material Composition ( C.) Index (g/cm.sup.3) AN Polyolefin ethylene/hexene-1 copolymer 129 44 0.95 0 base (CAS # 24213-02-9) polymer 1 Polyolefin propylene-ethylene copolymer 145 35 0.9 0 base (CAS # 9010-79-1) with polymer2 800 ppm Irganox 3114 blended in Polyolefin propylene-ethylene copolymer 145 35 0.9 0 base (CAS# 9010-79-1) polymer 3 or PP Polyolefin 1-1.5% Maleic anhydride 12 0.95 13 base grafted polyethylene polymer 4 (CAS# 25213-02-9) Coupling 4-7% maleic anhydride 130 >1000 45 agent 1 grafted polypropylene Coupling 4-7% maleic anhydride 110 >1000 45 agent 2 grafted polyethylene (CAS# 9006-26-2) stabilizing Ethylene Acrylic acid 0.96 300 155 agent (21 mol. %) copolymer (CAS# 9010-77-9)

Synthesis Examples: Polyolefin Dispersion Preparation

(4) The solid composition of the prototype dispersions were kept the same, i.e., 70 wt. % polyolefin base polymer/22.5% olefinic stabilizing agent/7.5 wt % coupling agent. Acid functionality was neutralized with dimethylethanolamine (DMEA, Acros Organics, CAS 108-01-0) at 150% of theoretical based on carboxylic acid present (calculated as the weighted average value of the measured acid numbers of the individual ingredients in the polyolefin dispersion compositions). Unless otherwise indicated in Table 1, above, or Table 2, below, the total resin blend, including any masterbatches, was fed into a 25 mm diameter twin screw extruder by means of a controlled rate feeder where it was forwarded and melted. The extruder temperature profile was ramped up to approximately 160 C. prior to the addition of the initial water and DMEA, and subsequently, dilution water was added. The extruder speed was 1200 rpm. Amine neutralizing agent and water were mixed together and fed to the extruder at the initial water introduction point. The dilution water was fed via two separate pumps, and it was introduced at two locations into the dilution zone of the extruder. The initial water and dilution water streams were pre-heated to the extruder temperature. At the extruder outlet, a back-pressure regulator was used to adjust to a pressure of approximately 300 psig inside the extruder barrel to reduce steam formation at the operating temperature. The resulting dispersions were cooled and filtered through 800, 200 and 50 micron bag filters followed by a 20 micron cartridge filter. The various compositions for each composition are shown in Table 2, below.

(5) TABLE-US-00003 TABLE 2 Dispersion Compositions MEK Resin composition Antioxidant and nominal loading double Example (wt ratio) (ppm on resin solids) (cycles) Comparative 70/22.5/7.5 Polyolefin 530 ppm Irganox 3114 in Polyolefin <25 Example 1 base polymer 2/stabilizing base polymer 2 agent/coupling agent 1 Comparative 70/22.5/7.5 Polyolefin 600 ppm Irganox 3114 post added 40 Example 3 base polymer 2/stabilizing plus 530 ppm Irganox 3114 in PP agent/coupling agent 1 Comparative 70/22.5/7.5 Polyolefin 600 ppm Irganox 1010 post added 85 Example 4 base polymer 2/stabilizing plus 530 ppm Irganox 3114 in PP agent/coupling agent 1 Comparative 70/22.5/7.5 PP/stabilizing 560 ppm Irganox 1010 dusted on PP <25 Example 5 agent/coupling agent 1 Comparative 70/22.5/7.5 PP/stabilizing 1100 ppm Irganox 1010 dusted on PP 90 Example 2 agent/coupling agent 1 Comparative 70/22.5/7.5 PP/stabilizing 600 ppm Hostanox-O3 antioxidant <25 Example 6 agent/coupling agent 1 post added plus 560 ppm Irganox 1010 dusted on PP Comparative 70/22.5/7.5 PP/stabilizing 1000 ppm Hostanox-O3 antioxidant 65 Example 7 agent/coupling agent 1 post added plus 560 ppm Irganox1010 dusted on PP during dispersion Example 1 70/22.5/7.5 PP/stabilizing 420 ppm Hostanox O3 melt blended <25 agent/coupling agent 1 in to dispersion through PP masterbatch Example 2 70/22.5/7.5 PP/stabilizing 630 ppm Hostanox O3 melt blended 185 agent/coupling agent1 in to dispersion through PP masterbatch Example 3 70/22.5/7.5 PP/stabilizing 840 ppm Hostanox O3 melt blended 200 agent/coupling agent 1 into dispersion through PP masterbatch Example 4 70/22.5/7.5 PP/stabilizing 530 ppm Hostanox O3 melt blended 200 agent/coupling agent 1 into dispersion through PP masterbatch + 530 ppm Irganox 3114 in PP resin Example 5 64/7/22/7 Polyolefin base 640 ppm Hostanox O3 melt blended 200 polymer 1/Polyolefin into dispersion through base polymer 1 base polymer 4/stabilizing masterbatch agent/coupling agent 2 Example 6 70/22.5/7.5 PP/stabilizing 420 ppm Hostanox O3 melt blended 200 agent/coupling agent 1 into dispersion through Masterbatch in coupling agent 1 Comparative 70/22.5/7.5 PP/stabilizing 840 ppm Irganox 1010 melt blended <25 Example 8 agent/coupling agent 1 into dispersion through PP masterbatch Comparative 70/22.5/7.5 PP stabilizing 840 ppm Irganox 3114 melt blended <25 Example 9 agent/coupling agent 1 into dispersion through PP masterbatch Comparative 70/22.5/7.5 PP 840 ppm Irganox 1330 melt blended <25 Example 10 masterbatches/stabilizing into dispersion through PP masterbatch agent/coupling agent 1

(6) As shown in Table 2, above, master batches of polypropylene (PP) polyolefin base polymer with various indicated amounts of antioxidant loading were prepared by melt blending. The antioxidant containing PODs were prepared by combining the indicated amounts of antioxidant containing masterbatches. For example, to achieve a 600 ppm level of Hostanox O3 antioxidants (AO) and 750 ppm level of Irganox 3114 AO, a 7000 g PP pellet mixture was prepared consisting of 3500 g of a mix of 42.9% PP masterbatch with 50 ppm Hostanox O3 AO and 57.1% of PP masterbatch with 2060 ppm Hostanox O3 AO (masterbatches) and 3500 g of a mix of 23.4% PP masterbatch with 126 ppm Irganox 3114 AO and 76.6% PP masterbatch with 1920 ppm Irganox 3114 AO (masterbatches). To the pellet mixture was added 2250 g of a polyolefin stabilizing agent and 750 g of coupling agent 1. The pellet mixture was combined with a mechanical stirrer to uniformly distribute pellet component. Several of these 10 kg batches were prepared and were fed to the emulsification extruder to prepare the POD, as described above.

(7) Antioxidant dispersions in polyolefins were melt blended or polyolefins having dusted on antioxidants were provided for making aqueous dispersion. Post addition of antioxidants was done by dissolving the indicated antioxidant in 1/1 butyl CELLOSOLVE/n-butanol mixture at 10 wt. % concentration and mixing the solution with dispersion without any further formulation steps.

(8) Coating Preparation:

(9) All coatings were applied to aluminum can body stock (X1178591212 clear aluminum can stock (All Foils Inc., Cleveland, Ohio) with a wire wound draw down bar to target a dry coating thickness of 7-10 microns. Coating curing was done at 225 C. for 4 minutes in a VWR 1640 forced air convection oven (VWR, Radnor, Pa.).

(10) Test Methods:

(11) MEK Double Rubs:

(12) MEK double rub testing was performed according to ASTM D 5402-06 Method 3 (2011) 2011) on the coatings made according to the Coating preparation using bleached cheese cloth (Grade 50) having 2824 threads per 2.54 cm2.54 cm square and a 906 g (32 ounce) ball peen hammer, wherein the cloth was fastened with a wire to the flat end of the hammer and rubbed against the coating back and forth across the coating, the cloth being re-dipped into MEK every 25 double rubs. The cloth was repositioned to a fresh area or replaced after every panel. The number reported in Table 2, above is total number of back and forth rub cycles until the coating is cut through and the substrate becomes visible in any area. An acceptable MEK Double rub result is 100 rubs or higher.

(13) As shown in Table 2, above, all coating compositions comprising masterbatches or antioxidant dispersions of hindered phenolic antioxidant containing an ester linkage in Examples 2 to 6 gave good MEK double rub results, indicating that the coatings formed therefrom had good thermal resistance. Example 1 did not have enough antioxidant when formed as an antioxidant dispersion in polypropylene. However, Example 6 gave excellent results with the same amount of hindered phenolic antioxidant dispersed as an antioxidant dispersion in a polymeric coupling agent. These examples indicate the preferred polymer for forming an antioxidant dispersion is a coupling agent or a polyolefin stabilizing agent having some water dispersibility and compatibility with the antioxidant. Example 4 indicates that the antioxidant dispersion can effectively comprise a second phenolic antioxidant not containing an ester linkage and lower the needed amount of the hindered phenolic antioxidant containing an ester linkage in the compositions. All of the Comparative Examples failed to include antioxidant dispersions, either as masterbatches or as dispersed in a polyolefin. In addition, the Comparatives 1, 8, 9 and 10 all failed in part because they failed to comprise a hindered phenolic antioxidant containing an ester linkage.