Polyolefin dispersion compositions for making high vapor transport hydrophobic coatings

Abstract

The present invention provides compositions for water vapor permeable hydrophobic coating comprising a blend of (i) a primary polyolefin dispersion of one or more large particle size polyolefins having a melting point of at least 95 C., and an average particle size of from 1 to 5 microns, and containing a volatile base and a 14 to 40 carbon long chain linear carboxylic acid dispersing agent, and (ii) a film forming second dispersion of one or more polymers having an average particle size of from 0.1 to 1.0 microns chosen from one or more polyolefins having a melting point from 50 to 90 C. further containing an at least partially neutralized olefin containing dispersing agent, one or more alkyl celluloses which further contain a plasticizer having a boiling point of 250 C. or greater and containing an at least partially neutralized olefin containing dispersing agent, and one or more acrylic emulsion polymers having a Tg of from 0 to 60 C. wherein the particle size ratio of the primary polyolefin dispersion to the second dispersion ranges from 3:1 to 29:1.

Claims

1. A composition comprising a blend of (i) a primary polyolefin dispersion of one or more large particle size polyolefins having a melting point of at least 95 C., and an average particle size of from 1 to 5 microns, and containing a volatile base and a 14 to 40 carbon long chain linear carboxylic acid dispersing agent, and (ii) a film forming second dispersion of one or more polymers having an average particle size of from 0.1 to 1.0 microns chosen from an amount of 10 to 30 wt. %, as solids of one or more polyolefins having a melting point from 50 to 90 C. further containing an at least partially neutralized olefin containing dispersing agent, an amount of not more than 7.5 wt. % as solids of one or more alkyl celluloses which further contain a plasticizer having a boiling point of 250 C. or greater and containing an at least partially neutralized olefin containing dispersing agent, and an amount of not more than 17.5 wt. %, as solids of one or more acrylic emulsion polymers having a Tg of from 0 to 60 C. or, wherein in the blend of primary polyolefin dispersion and the second dispersion, the particle size ratio of the primary polyolefin dispersion to the second dispersion ranges from 3:1 to 29:1.

2. The composition as claimed in claim 1, wherein the melting point of the one or more polyolefins in the primary polyolefin dispersion ranges from 95 to 180 C.

3. The composition as claimed in claim 1, wherein the amount of the second dispersion of one or more polymer ranges from 10 to 27.5 wt. %.

4. The composition as claimed in claim 1, wherein the average particle size of the one or more polymer in the second dispersion ranges from 0.12 to 0.7 microns.

5. The composition as claimed in claim 1, wherein the melting point of the one or more polymer in the second dispersion ranges from 60 to 90 C.

6. The compositions in accordance with 1, above, further comprising one or more pigments, fillers or extenders.

7. The composition as claimed in claim 1, wherein the (i) primary polyolefin dispersion contains as a dispersing agent a long chain linear carboxylic acid which is a linear fatty acid.

8. The composition as claimed in claim 1, wherein the (i) one or more polymers in the primary polyolefin dispersion is chosen from a polyolefin elastomer, a high density polyethylene, ethylene-propylene copolymers, polypropylenes, olefin block copolymers, and mixtures thereof.

9. The composition as claimed in claim 1, wherein the (ii) one or more polymers in the second dispersion is a polyolefin and comprises a polyolefin plastomer, a linear low density polyethylene, an ethylene-C.sub.4 to C.sub.12 olefin copolymers, or mixtures thereof.

10. The composition as claimed in claim 1, wherein the melting point of each of the one or more polyolefins in the (i) primary polyolefin dispersion is at least 20 C. higher than the melting point of each of the one or more polymers in the film forming second dispersion.

Description

(1) Examples:

(2) 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.

(3) TABLE-US-00001 TABLE 1 Raw Materials for Polyolefin Dispersions Melting Point Melt Density Material Composition ( C.) Index (g/cm.sup.3) TE* (%) Primary polyolefin Polyolefin elastomer 96 30 0.902 910 dispersion 1 Primary polyolefin Ethylene-octene block 111 5.0 0.887 1000 dispersion 2 copolymer primary polyolefin High density polyethylene 128 44 0.951 10 dispersion 3 Second dispersion polymer Ethylene/ethylacrylate 95 21 0.930 750 5 OR Primary dispersion copolymer (20% EA) polymer 4 Primary polyolefin Maleated high density 127 12 0.954 100 dispersion 4 polyethylene Second dispersion polymer Ethylene/octene olefin 68 1000 0.87 110 1 plastomer Second dispersion polymer Ethylene/octene olefin 70 500 0.874 190 2 plastomer Base 1 Dimethyl ethanolamine (DMEA) Base 2 Potassium hydroxide (KOH) Dispersing agent 1 Sodium laureth sulfate anionic surfactant (70% w/w in water) Olefin containing dispersing Ethylene acrylic acid 77.2 300 0.958 390 agent 1 copolymer (20% AA) Olefin containing dispersing Ethylene acrylic acid 75 C. 1300 0.955 350 agent 2 copolymer (20% AA) Second dispersion polymer EHA, Sty, MMA, MAA 3.5 40.sup.1 n/a n/a n/a 3 wt. % MAA (as % of mers) single stage emulsion polymer Long chain linear carboxylic (80/20) Long chain linear 92 120 acid dispersing agent (~25 C. primary carboxylic avg.) acid/polyethylene Modified polyolefin 1 Hydrocarbon/maleic 75 154 anhydride copolymer Modified polyolefin 2 Maleic anhydride (~5.5 123 45 0.99 wt. %) modified PE wax Second dispersion polymer Ethyl cellulose n/a n/a n/a n/a 4 .sup.1Glass transition temperature (DSC). *Tensile elongation at break

(4) TABLE-US-00002 TABLE 2 Dispersion Compositions Dispersion Composition (wt. %, solids) A 80% Second dispersion polymer 1; 20% Olefin containing dispersing agent 2 B 84% Second dispersion polymer 5; 12% Modified polyolefin 2; 4% Dispersing agent 1 C 95.5% Second dispersion polymer 5; 4.5% Long chain linear carboxylic acid dispersing agent +KOH (neutralizing agent) D 80% Second dispersion polymer 5; 20% Olefin containing dispersing agent 1 E 94.2% Second dispersion polymer 1; 5.8% Dispersing agent 1 F 80% Second dispersion polymer 5; 20% Olefin containing dispersing agent 1 G 78% Primary polyolefin dispersion 3; 15% Modified polyolef in 2; 7% Long chain linear carboxylic acid dispersing agent H 80% Second dispersion polymer 1; 20% Olefin containing dispersing agent 2 with DMEA I 88% Primary polyolefin dispersion 1; 7% Modified polyolefin 2; 5% Long chain linear carboxylic acid dispersing agent with DMEA J 86% Primary polyolefin dispersion 2; 7% Modified polyolefin 1; 7 Long chain linear carboxylic acid dispersing agent with DMEA K 74% Second dispersion polymer 4; 17% dibutyl sebacate.sup.1; 9% oleic acid.sup.2 with ammonia L 78% Primary polyolefin dispersion 3; 15% Modified polyolef in 2; 7% Long chain linear carboxylic acid dispersing agent M Second dispersion polymer 2; Olefin containing dispersing agent 1 (80/20) N Second dispersion polymer 2; Olefin containing dispersing agent 1 (80/20) O Second dispersion polymer 3; Measured Tg - 40 C.; 41.5 wt. % solids; pH 7.5, contains ammonia P Same as E, above. .sup.1Plasticizer; .sup.2Long chain linear carboxylic acid dispersing agent.

SYNTHESIS EXAMPLES

Dispersion Preparation

(5) Dispersions A to P

(6) Aqueous dispersions A to P having compositions as disclosed in Table 2, above, were formed from raw materials disclosed in Table 1, above, using the conditions as described in Table 3, below, were prepared using the following general procedure:

(7) Components 1 to 3 listed in Table 3, below, were fed into a 25 mm diameter twin screw extruder using a controlled rate feeder; using the feed rate in grams/minute (g/min) as indicated in Table 3. Components 1 to 3 were forwarded through the extruder and melted to form a liquid melt material.

(8) The extruder temperature profile was ramped up to the temperature listed in the Polymer Melt Zone column of Table 3, below. Water and volatile base and/or neutralizing agent were mixed together and fed to the extruder at a rate indicated in Table I for neutralization at an initial water introduction site. Then dilution water was fed into the extruder in one or two locations (1.sup.st and 2.sup.nd locations) via two separate pumps at the rates indicated in Table 3. The extruder temperature profile was cooled back down to a temperature below 100 C. near the end of the extruder. The extruder speed was around 470 rpm in most cases as recorded in Table 3. At the extruder outlet, a backpressure regulator was used to adjust the pressure inside the extruder barrel to a pressure adapted to reduce steam formation (generally, the pressure was from 2 MPa to 4 MPa).

(9) Each aqueous dispersion exited from the extruder and was filtered through a 200 micrometer (m) filter. The resultant filtered aqueous dispersions had a solids content measured in weight percent (wt. %); and the solids particles of the dispersion had a volume mean particle size measured in microns and recorded in Table 3, below. In some cases the particle size mode is also recorded. The solids content of the aqueous dispersion was measured using an infrared solids analyzer; and the particle size of the solids particles of the aqueous dispersion was measured using a COULTER LS-230 particle size analyzer (Beckman Coulter Corporation, Brea, Calif.). The solids content and the average particle size (PS) of the solids particles of the dispersion are indicated in Table 3, below.

(10) TABLE-US-00003 TABLE 3 Composition and Process Conditions for Dispersions A to P Dilution Base/ Water Extruder Initial Water Surfactant 1.sup.st/2.sup.nd Temp in Disper- Polymer Part 2 Part 3 feed rate feed rate feed rate Polymer Melt Extruder sion (feed rate, g/min) (feed rate, g/min) (feed rate, g/min) (g/min) (g/min) (g/min) Zone ( C.) Speed (rpm) A Second n/a olefin containing (14.4) DMEA 85/0 90 470 dispersion dispersing agent 2 (5.8) polymer 1 (15.1) (60.5) B Primary Modified n/a (3.4) Dispersing 105 150 450 polyolefin Polyolefin 2 agent 1 dispersion 4 (13.4) (6.4) (93.7) C Primary n/a Long chain linear (2.0) 23% wt. 106/0 160 470 dispersion carboxylic acid KOH polymer 4 dispersing agent (2.2) (108.4) (5.1) D Primary n/a olefin containing (12.0) DMEA 70/0 160 470 dispersion dispersing agent 1 (4.6) polymer 4 (15.1) (60.5) E Second n/a n/a (2.0) Dispersing 60/0 80 470 dispersion agent 1 polymer 1 (53) (3.3) F Primary n/a olefin containing (18.0) DMEA 110/0 160 470 dispersion dispersing agent 1 (6.9) polymer 4 (22.7) (90.8) G Primary Modified Long chain linear (18.3) DMEA 80/0 160 470 polyolefin Polyolefin carboxylic acid (2.5) dispersion 3 2 (11.3) dispersing agent (59.0) (5.3) H Second n/a olefin containing (14.4) DMEA 85/0 90 470 dispersion dispersing agent 2 (5.8) polymer 1 (15.1) (60.5) I Primary Modified Long chain linear (11.5) DMEA 75/0 160 470 polyolefin Polyolefin carboxylic acid (1.4) dispersion 1 2 dispersing agent (3.8) (66.5) (5.3) J Primary Modified Long chain linear (7.8) DMEA 80/0 130 470 polyolefin Polyolefin 1 carboxylic acid (3.7) dispersion 2 (5.3) dispersing agent (65.0) (5.3) K Second Dibutyl Oleic acid (14.6) 28% 140/0 145 470 dispersion sebacate (5.1) ammonia polymer 4 (9.6) (2.2) (42.0) L Primary Modified Long chain linear (73.1) DMEA 240/110 160 1200 polyolefin Polyolefin carboxylic acid (8.9) dispersion 3 2 (45.4) dispersing agent (235.9) (21.2) M Second n/a Modified Polyolefin 1 (15.5) DMEA 90/0 90 470 dispersion (15.1) (5.8) polymer 2 (60.4) N Second n/a Modified Polyolefin 1 (15.5) DMEA 90/0 90 470 dispersion (15.1) (5.6) polymer 2 (60.4) O Second n/a n/a n/a n/a n/a n/a n/a dispersion polymer 3 P Second n/a n/a (2.0) Dispersing 60/0 80 470 dispersion agent 1 polymer 1 (53) (3.3) Particle % Size Vmean Viscosity cP Dispersion Solids (microns) pH (Rv2, 50 rpm) A 38.11 0.19 9.9 407 B 50.5 0.79 3 100 C 54.03 1.6 11 n/m D 49.09 3.4 9.97 1672 E 53.9 0.64 3.7 596 F 49.1 11.2 n/m G 48.29 2.5 9.5 320 H 42.53 0.152 9.8 1250 I 51.08 2.78 9.2 1920 J 46.76 2.86 9.9 722 K 26.5 0.19 9.0 25 L 50.04 2.71 9.2 440 M 34.31 0.523 9.8 168 (128 nm mode) N 35.7 0.44 9.8 248 (135 nm mode) O n/a n/a n/a n/a P 53.9 0.64 3.7 596

(11) Coating preparation: Films of each sample were made using a 152.4 micron (6 mil) drawdown bar on either uncoated printer paper, or coated Leneta chart paper. The films were cured at 90 C. for 10 minutes.

(12) Test methods:

(13) Moisture vapor transport: Measurements were taken by filling glass jars with a known amount of deionized (DI) water, covering the top of each jar with either a control (uncoated printer paper) or a paper sample coated with the indicated composition. The edges of the paper were sealed with electrical tape. The samples were placed in a constant temperature (23 C.) constant relative humidity (50%) chamber. The initial weight was recorded and weight loss was measured for up to 14 days to determine the water loss through the coated paper or control. The rate was calculated in grams/m.sup.2-day and compared to the uncoated paper control.

(14) One aspect of the present invention is the ability to have high moisture vapor transport through these coatings (acceptable performance is >50% of the moisture vapor transport rate of the uncoated substrate (labeled control).

(15) Hydrophobicity: Hydrophobicity of each coating was evaluated by measuring the contact angle of a water droplet on the surface of the coating. Contact angle measurements were made using a VCA Optima Contact Angle device (AST Products, Inc., Billerica, Mass.), with a 1 l drop of deionized water. Values reported above are the average of three measurements. Acceptable contact angles are at least 115 degrees.

(16) The second aspect of this invention is the ability of the coating to be a barrier to liquid water. A way to measure the water repellency of a coating is by measuring the contact angle of a water droplet on the surface of the coating. The higher the contact angle, the more hydrophobic the coating.

(17) While the coating made with the blend of Dispersion G (primary polyolefin dispersion) and Dispersion B (secondary polyolefin dispersion) have good vapor transport, it lacks good liquid water barrier properties as evidenced by the low contact angle (how well liquid water wets the coating surface). In contrast, the coating made with Dispersion A as the binder POD (secondary polyolefin dispersion) has very good moisture vapor transport properties and very high water contact angles (>123). Results of performance testing of the various Examples are reported in Table 4, below.

(18) TABLE-US-00004 TABLE 4 Moisture Vapor Transport (MVTR) and Contact Angle Measurements on Uncoated Paper MVTR Primary Second Wt.% Second Particle Contact (g-m.sup.2/day) Example Dispersion Dispersion Dispersion Size Ratio Angle 704 % of Average Control (uncoated Printer Paper) (n = 7) Control Inventive Examples 1 I H 5 18 134 585.34 83.1 2 I H 10 18 130 455.36 64.7 3** I H 15 18 131 313.89 44.6 4** I H 20 18 117 168.00 23.9 5 L N 5 22 134 565.9 80.4 6 L N 10 22 130 550.0 78.1 7 L N 15 22 131 426.2 60.5 8 L N 20 22 117 407.6 57.9 9 G A 10 13.2 123 595.9 84.6 10 G A 20 13.2 131 412.0 58.5 11** G A 30 13.2 123 146.8 20.8 12 G A 5 13.2 126 618.9 87.9 13 G P 5 3.2 123 641.0 91.0 14 G P 10 3.2 117 604.8 85.9 15 G P 15 3.2 115 511.1 72.6 16 L K 5 14 119 576.5 81.9 17 L 0 5 29 129 466.9 66.3 18 L 0 10 29 127 499.6 71.0 19 L 0 15 29 117 412.0 58.5 Comparative Examples 20 L 0 20 29 93 546.4 77.6 21 G P 20 3.2 112 458.0 65.0 22 L K 10 14 107 577.4 82.0 23 L K 15 14 99 594.2 84.4 24 L K 20 14 107 592.4 84.1 25 B H 10 5.2 ND 646.3 91.8 26 B H 20 5.2 52 489.8 69.6 27 B H 30 5.2 37 47.7 6.8 28 B H 40 5.2 52 46.9 6.7 29 F H 5 74 104 17.7 2.5 30 F H 10 74 106 17.7 2.5 31 F H 15 74 107 16.8 2.4 32 F H 20 74 106 15.0 2.1 33 E* H 10 4.2 58 322.7 45.8 34 E* H 20 4.2 61 17.7 2.5 35 E* H 30 4.2 59 15.9 2.3 36 E* H 40 4.2 65 15.9 2.3 37 D H 5 22 105 36.25 5.1 38 D H 10 22 107 18.57 2.6 39 D H 15 22 104 18.57 2.6 40 D H 20 22 107 15.92 2.3 41 J H 5 19 122 182.14 25.9 42 J H 10 19 123 48.63 6.9 43 J H 15 19 116 38.02 5.4 44 J H 20 19 No No ND data data 45 G B 5 3.2 115 602.1 85.5 46 G B 10 3.2 103 595.9 84.6 47 G B 15 3.2 90 580.0 82.4 48 G B 20 3.2 91 596.8 84.8 **-Denotes Comparative; *-Denotes second dispersion polymer used in place of primary polyolef in dispersion polymer

(19) Inventive Examples have both high moisture vapor transport measurements, as well has high (>115 degree) contact angles. Exceptions were those in which too high an amount of the second dispersion polymer were present; in those Examples 3, 4 and 11, the second dispersion polymer was soft and fluid and filled in too much interstitial space and reduced the porosity of the coating. Thus, the preferred amount of the second dispersion polymer in the Dispersion I/Dispersion H blend is <15% the total solids of the primary polyolefin and the secondary polymer in the composition. For the Dispersion G/Dispersion A blends, the preferred amount of the second dispersion polymer is <30% of the total solids of the primary and secondary polymer in the composition. In Example 21, too much of the alkyl cellulose interfered with hydrophobicity; it is preferable to use 17.5% or less alkyl cellulose, based on the total solids of the primary polyolefin and the secondary polymer in the composition. Too much acrylic binder in the Dispersion L/Dispersion O blends reduces the contact angle due to the increased amount of surfactant introduced into the system, thus reducing the hydrophobicity of the blend.