Polyolefin dispersion containing a primary aliphatic amide additive

Abstract

The present invention relates to a composition comprising a) poly-C2-C3-olefin particles, b) a dispersant, and c) a C5-C26-alkyl primary aliphatic amide. The composition of the present invention is useful for preparing a coating having desirable water vapor transmission rate and coefficient of friction properties on paper.

Description

Technical Field

[0001] The present invention relates to a polyolefin dispersion, a primary aliphatic amide additive, and more specifically, a composition containing a C5-C 26 -alkyl primary aliphatic amide. The composition has been found to be useful as a coating for paper substrates.

Background Art

[0002] Consumer demands for sustainable paper used in packaging are focused on improving the barrier properties and recyclability of coated paper. The barrier performance of paper is known to be enhanced with polyolefin coatings, which also provide heat-sealing properties. Furthermore, it has been difficult to achieve a coating surface density (coating weight) of less than 10 g / m 2 by applying an extruded polyolefin layer onto a paper substrate. Achieving these ultra-low coating weights is particularly important in flexible packaging applications where the paper substrate has a basis weight (grammage) of less than 60 g / m 2 and the market requires a fiber recycling of more than 85% by weight based on the mass of the article.

[0003] As disclosed in U.S. Patent No. 10,612,193 (B2) (column 2, table 2), ultrathin coatings can be prepared by applying an aqueous polyolefin emulsion onto a paper substrate and subsequently curing it. Nevertheless, it remains difficult to meet the targets for water vapor transmission rate (MVTR) and coefficient of friction (CoF). Therefore, preparing a thin coating that meets the application requirements for MVTR and provides recyclable packaging would be an advancement in the field of coated paper substrates.

Summary of the Invention

[0004] The present invention addresses a need in the art by providing a composition, which composition comprises a) poly-C2-C3-olefin particles, b) a dispersant which is a copolymer of ethylene and a carboxylic acid monomer or a salt thereof, and c) an aqueous dispersion of a C5-C 26 -alkyl primary aliphatic amide, wherein the concentration of the polyolefin particles ranges from 40 to 95 weight percent, the concentration of the dispersant ranges from 4 to 50 weight percent, and the concentration of the C5-C 26 -alkyl primary aliphatic amide ranges from 0.5 to 5 weight percent, and these concentrations are based on the weight of the poly-C2-C3-olefin particles, the dispersant, and the C5-C 26 -alkyl primary aliphatic amide. The composition of the present invention can be used to provide an ultrathin coating on a paper substrate having advantageous water vapor transmission rate and coefficient of friction properties.

DETAILED DESCRIPTION OF THE INVENTION

[0005] The present invention is a composition which composition comprises a) poly-C2-C3-olefin particles, b) a dispersant which is a copolymer of ethylene and a carboxylic acid monomer or a salt thereof, and c) an aqueous dispersion of a C5-C 26 -alkyl primary aliphatic amide, wherein the concentration of the polyolefin particles ranges from 40 to 95 weight percent, the concentration of the dispersant ranges from 4 to 50 weight percent, and the concentration of the C5-C 26 -alkyl primary aliphatic amide ranges from 0.5 to 5 weight percent, and these concentrations are based on the weight of the poly-C2-C3-olefin particles, the dispersant, and the C5-C 26 -alkyl primary aliphatic amide.

[0006] As used herein, "poly-C2-C3-olefin particles" refers to polyethylene particles, polypropylene particles, and poly(ethylene-propylene) copolymer particles. Polyethylene is ethylene-C4-C 10-α-olefin copolymers (i.e., linear low density polyethylene), such as, for example, ethylene-1-butene copolymers, ethylene-1-hexene copolymers, and ethylene-1-octene copolymers. Commercially available linear low density polyethylene is AFFINITY PL1280 LLDPE ethylene-octene copolymer (a registered trademark of The Dow Chemical Company or its affiliates). Polyethylene may also be, for example, high density polyethylene commercially available as DOW (trademark) DMDA-8940 NT 7 HDPE resin, or low density polyethylene. An example of a commercially available ethylene-propylene copolymer is VERSIFY (trademark) 4200 propylene-ethylene copolymer (a trademark of The Dow Chemical Company or its affiliates), and a commercially available polypropylene is Braskem 6D43 random copolymer. Particles that are believed to contain a C2-C3 polyolefin and some amount of a dispersant and a primary aliphatic amide associated therewith preferably have a volume average particle size in the range of 200 nm or 300 nm to 5 μm or 3 μm or 1.5 μm when measured by dynamic light scattering.

[0007] The dispersant is a copolymer of ethylene and a carboxylic acid monomer or a salt thereof. Examples of suitable dispersants include ethylene-acrylic acid copolymers, ethylene-methacrylic acid copolymers, and ethylene-itaconic acid copolymers, as well as their lithium, sodium, and potassium salts.

[0008] The weight-to-weight ratio of ethylene structural units to carboxylic acid monomer is preferably in the range from 95:5, more preferably from 90:10, most preferably from 85:15, to 70:30, more preferably to 75:25. As used herein, the term "structural unit" of a specified monomer refers to the residue of the monomer after polymerization. For example, the structural unit of methacrylic acid is as follows.

Chemical formula

[0009] Examples of commercially available dispersants include PRIMACOR™ 5980i ethylene-acrylic acid copolymer and NUCREL 960™ ethylene-methacrylic acid copolymer (trademarks of The Dow Chemical Company or its affiliates).

[0010] C5~C 26 -alkyl primary aliphatic amides may be linear or branched and may be saturated or partially unsaturated having one or two or three double bonds. The aliphatic amide may also be a C 10- ~C 24 -alkyl primary aliphatic amide or a C 16 ~C 22 -alkyl primary aliphatic amide. Examples of suitable aliphatic amides include linear and branched C 18- -alkyl monounsaturated aliphatic amides, linear and branched C 18 -alkyl saturated aliphatic amides, linear and branched C 22 -alkyl monounsaturated aliphatic amides, and linear and branched C 22 -alkyl saturated aliphatic amides. The C5~C 26 -alkyl primary aliphatic amide preferably has a melting point in the range of 50°C or 65°C to 115°C or 100°C or 90°C.

[0011] The concentration obtained by subtracting any associated dispersant or primary aliphatic amide from the poly-C2~C3-olefin particles is in the range of 40 or 60 or 70 weight percent to 95 or 90 weight percent based on the weight of the polyolefin, dispersant, and C5~C 26 -alkyl primary aliphatic amide. The concentration of the dispersant is in the range of 4 or 9 or 15 weight percent to 50 or 40 or 30 weight percent based on the weight of the polyolefin particles, dispersant, and C5~C 26 -alkyl aliphatic amide. The C5~C 26- The concentration of the alkyl primary aliphatic amide is from 0.5 or 1 to 5 or 4 or 3 weight percent based on the weight of the polyolefin particles, the dispersant, and the C5 - C 26 - alkyl aliphatic amide.

[0012] To adjust the pH of the composition to a desired level, preferably in the range of 8 - 11, a neutralizing agent such as KOH is advantageously used.

[0013] The composition preferably further comprises a stabilizing amount of an anionic surfactant such as a C 10 - C 24 linear or branched alkyl or aralkyl carboxylate, sulfate, or phosphate, or a nonionic surfactant such as a secondary alcohol ethoxylate or an ethylene oxide propylene oxide block copolymer surfactant. The composition can be prepared as shown in the Examples section.

[0014] 1 g / m 2 or 2 g / m 2 or 5 g / m 2 to 2 20 g / m 2 or 12 g / m 2 or 10 g / m

[0015] Methods for preparing the coated substrate and for measuring the coating weight UPM Brilliant 62 Glassine Paper (basis weight 62 g / m 2 ) was coated with the polyolefin dispersion using a drawdown bar and dried in a forced air oven at 100 °C for 2 minutes to give 8 g / m 2The final coating surface density (coating weight) (coating thickness of about 8 - 9 μm) was achieved. The coated UPM paper and the uncoated UPM paper were punched with a circular die to form discs with a specific diameter (D cm), and the coating weight was measured. The coated disc (W1) was weighed against the uncoated disc (W2), and the coating weight was calculated by the following formula.

Number

[0016] Measurement of water vapor transmission rate The water vapor transmission rate (MVTR) was determined according to ASTM E96 / E96M. The coated paper sample was sealed to the open end of a permeable cup, and subsequently the sample was exposed to a controlled temperature and humidity environment (typically a humidity chamber). The MVTR was determined based on measuring the mass uptake of the cup as a function of time.

[0017] Measurement of coefficient of dynamic friction The coefficient of dynamic friction (CoF) was measured using a Texture Analyzer equipped with a sliding friction rig according to TAPPI T549. One piece of the coated paper was fixed to the bottom of a 200 g weight thread with the coated side facing down. Another piece of the coated paper was fixed to a flat surface with the coated side facing up. A thread was attached to the thread, and the thread was pulled so that it crossed at least a 100 mm plane at a speed of 2.5 mm / s. The force Fd (unit: gram weight) reached at the plateau when the thread was moved steadily was recorded. The dynamic CoF was calculated as Fd / 200.

[0018] Calculation of degree of neutralization The degree of neutralization of the polyolefin dispersion was determined by the following formula.

Number

Example

[0019] Table 1 shows the components and feed rates used to prepare Examples 1 to 4 and Comparative Examples 1 to 5. The feed rates are shown in parentheses. The general procedure is shown in Table 1 below. PO refers to polyolefin. Amide refers to aliphatic amide. H2O o refers to the initial water ratio. H2O d refers to the dilution water ratio. The solid content refers to the solid content weight % of polyolefin, dispersant, aliphatic amide, and anionic surfactant in the dispersion, and PS refers to the particle size in micrometers determined by dynamic light scattering.

[0020] PL1280 refers to AFFINITY (trademark) PL 1280 LLDPE ethylene-octene copolymer. V4200 refers to VERSIFY (trademark) ethylene-propylene copolymer. N960 refers to NUCREL (trademark) N960 ethylene-methacrylic acid copolymer. OA (oleamide, melting point 70 °C) is C 18 -alkyl mono-unsaturated primary aliphatic amide. EA (erucamide, melting point 80 °C) is C 22 -alkyl mono-unsaturated primary aliphatic amide. BA (behenamide, melting point 112 °C) is C 22 -alkyl saturated primary aliphatic amide. EBS (ethylene bis-stearamide, melting point 145 °C) is C 38 -alkyl secondary aliphatic amide. OPA (oleyl palmitamide, melting point 60 - 66 °C) is C 34 -alkyl secondary aliphatic amide. SEA (stearyl erucamide, melting point 70 - 75 °C) is C 40 -alkyl secondary aliphatic amide.

[0021] The neutralization degrees of Comparative Examples 1 to 4 and Examples 1 to 6 were 75%, and the neutralization degrees of Comparative Example 5 and Example 7 were 80%.

[0022]

Table 1

[0023] General procedure for preparing a polyolefin dispersion which is an aqueous dispersion The aqueous dispersion was prepared by the following general procedure.

[0024] PO, N960, and amide (except for Comparative Examples 1 and 5) were fed into a 25 mm diameter twin-screw extruder using separately controlled speed feeders. An anionic surfactant (oleic acid) was pumped as a liquid into the melt zone of the extruder at a feed rate of 3.4 mL / min using an Isco syringe pump. PO, N960, and amide were passed through the extruder and melted to form a liquid melt material which is an intermediate.

[0025] The temperature profile of the extruder was raised to a maximum of 150 °C. Water and 30% KOH aqueous solution were mixed, and after a uniform polymer melt was formed, it was fed into the extruder at the first water introduction location, and then dilution water was fed into the extruder. The extruder speed was 450 rpm for all samples except for Comparative Example 5 where the extruder speed was 400 rpm. At the extruder outlet, a back pressure regulator was used to adjust the pressure inside the extruder barrel to a pressure adapted to reduce steam formation, generally in the range of 2 MPa to 4 MPa.

[0026] Each aqueous dispersion was taken out from the extruder and first filtered through a 200 μm filter. The solid content of the dispersion was measured using an infrared solid analyzer, and the volume average particle size of the polymer particles was measured using a COULTER (trademark) LS-230 particle size analyzer (Beckman Coulter Corporation, Fullerton, CA).

[0027] Table 2 shows the MVTR and CoF of the examples and comparative examples. The coating thickness of each sample was 8 gsm. PO:N960:amide refers to the w / w / w ratio of polyolefin, dispersant, and aliphatic amide.

[0028]

Table 2

[0029] The data show the improvement in MVTR of coatings containing primary aliphatic amides when compared to either coatings without amide additives or coatings containing secondary aliphatic amides. For certain applications, a dynamic CoF of 0.3 or less is acceptable, and for other applications, a CoF of less than 0.2 is required.

Claims

Claim 1 A composition comprising: a) poly-C ２ to C ３ -olefin particles, b) a dispersant which is a copolymer of ethylene and a carboxylic acid monomer or a salt thereof, and c) an aqueous dispersion of a C ５ to C ２６ -alkyl primary aliphatic amide, wherein the concentration of the polyolefin particles ranges from 40 to 95% by weight, the concentration of the dispersant ranges from 4 to 50% by weight, and the concentration of the C ５ to C ２６ -alkyl primary aliphatic amide ranges from 0.5 to 5% by weight, and the concentrations are based on the weights of the poly-C ２ to C ３ -olefin particles, the dispersant, and the C ５ to C ２６ -alkyl primary aliphatic amide, a composition. Claim 2 The dispersant is an ethylene-acrylic acid copolymer or a salt thereof, or an ethylene-methacrylic acid copolymer or a salt thereof, and the C ５ to C ２６ -alkyl primary aliphatic amide is a C １０ to C ２４ -alkyl primary aliphatic amide, and the composition according to claim 1. Claim 3 Said C １０ to C ２４ -alkyl primary aliphatic amide has a melting point in the range of 50°C to 115°C, and the C １６ to C ２２ -alkyl primary aliphatic amide, and the poly-C ２ to C ３ -olefin particles are ethylene-C ４ to C １０ -α-olefin copolymer particles. The composition according to claim 2 Claim 4 The ethylene-C ４ -C １０ -α-olefin copolymer particles are ethylene-1-octene copolymer particles, and the composition according to claim 3. Claim 5 Said C １０ ~C ２４ -alkyl primary aliphatic amide is a C having a melting point in the range of 50°C to 115°C １６ ~C ２２ -alkyl primary aliphatic amide, and the poly-C ２ ~C ３ -olefin particles are polypropylene particles. The composition according to claim 2 Claim 6 Said C １０ ~C ２４ -alkyl primary aliphatic amide has a melting point in the range of 50°C to 115°C, and is a C １６ ~C ２２ -alkyl primary aliphatic amide, and the poly-C ２ ~C ３ -olefin particles are poly(ethylene-propylene) copolymer particles. The composition according to claim 2. Claim 7 The poly-C ２ -C ３ -olefin particles, the dispersant, and the C １０ -C ２４ -alkyl primary aliphatic amide, based on the weight of the poly C ２ -C ３ The concentration of the olefin is in the range of 60 to 90% by weight, the concentration of the dispersant is in the range of 9 to 40% by weight, and the C １０ -C ２４ The concentration of the alkyl primary aliphatic amide is in the range of 1 to 4% by weight. The composition according to claim 2 Claim 8 Said poly-C ２ -C ３ olefin particles, said dispersant, and said C １６ -C ２２ -alkyl primary aliphatic amide, based on the weight of said poly-C ２ -C ３ -olefin concentration is in the range of 60 to 90% by weight, the concentration of said dispersant is in the range of 9 to 40% by weight, and the concentration of said C １６ -C ２２ -alkyl primary aliphatic amide is in the range of 1 to 4% by weight, the composition according to any one of claims 3 to 6.

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