Coated paper article

Abstract

The present invention relates to an article comprising paper coated with a coating, the coating comprising a poly-C2-C3-olefin, a dispersant, and a C5-C 26 -alkyl primary aliphatic amide, wherein the coating has a coating weight in the range of 1 g / m 2 to 20 g / m 2 . The article of the present invention has desirable water vapor transmission rate and coefficient of friction characteristics.

Description

[Technical field]

[0001] The present invention relates to coated paper articles, and more particularly to paper substrates coated with a polyolefin coating. The coated paper substrates have been found to have useful moisture vapor transmission rate properties.

[0002] Consumer demand for sustainable papers used in packaging has led to interest in improving the barrier properties and recyclability of coated papers. The barrier performance of paper is known to be enhanced with polyolefin coatings, which also provide heat seal properties. Furthermore, the application of an extruded polyolefin layer onto a paper substrate has led to an increase in the barrier properties of papers up to 10 g / m2. 2 It has been difficult to achieve coating areal densities (coating weights) below 60 g / m. Achieving these ultra-low coating weights is difficult when the paper substrate is 60 g / m 2 This is particularly important in flexible packaging applications where the market requires greater than 85% fiber recycling by weight based on the mass of the article, with paper having areal densities (basis weights) less than 100%.

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

[0004] The present invention relates to a poly-C2-C3-olefin, a dispersant, and a C5-C 26 The present invention addresses the need in the art by providing an article comprising a paper overlying a dry coating comprising: 2~20 g / m 2 has a coating weight in the range of. The article of the present invention has advantageous water vapor transmission rate and coefficient of friction characteristics.

Mode for Carrying Out the Invention

[0005] The present invention relates to an article comprising paper over which a dry coating is applied, the coating comprising a poly-C2-C3-olefin, a dispersant, and a C5-C 26 -alkyl primary aliphatic amide, wherein the coating has a coating weight in the range of 1 g / m 2 ~20 g / m 2 has a coating weight in the range of. The article of the present invention has advantageous water vapor transmission rate and coefficient of friction characteristics.

[0006] As used herein, "poly-C2-C3-olefin" refers to polyethylene, polypropylene, and poly(ethylene-propylene) copolymers. Polyethylene may be an ethylene-C4-C 10 -α-olefin copolymer (i.e., linear low density polyethylene), for example, an ethylene-1-butene copolymer, an ethylene-1-hexene copolymer, and an ethylene-1-octene copolymer. A 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.

[0007] The article of the present invention comprises poly-C2-C3-olefin particles, a dispersant, and C5-C 26A wet coating of a composition comprising an aqueous dispersion of an alkyl primary aliphatic amide, preferably having a pH in the range of 8 to 11, is applied to paper and then the wet coating is preferably dried at an elevated temperature to remove water, which is conveniently prepared.

[0008] The poly-C2-C3 olefin particles are believed to contain a C2-C3 polyolefin and some amount of a dispersant and a primary aliphatic amide associated therewith, and 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.

[0009] The dispersant is a copolymer of ethylene and a carboxylic acid monomer or its salt. Examples of suitable dispersants include lithium, sodium, and potassium salts of ethylene-acrylic acid copolymers, ethylene-methacrylic acid copolymers, and ethylene-itaconic acid copolymers.

[0010] 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, up to 70:30, more preferably up 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.

[0011]

Chemical formula

[0012] 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).

[0013] C5-C26 -alkyl primary aliphatic amides may be linear or branched and may be saturated or partially unsaturated with 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. C5-C 26 -alkyl primary aliphatic amides preferably have a melting point in the range of 50 °C or 65 °C to 115 °C or 100 °C or 90 °C.

[0014] The concentration of poly-C2-C3-olefin in the coating is preferably in the range from 40 or 60 or 70 weight percent to 95 or 90 weight percent, based on the weight of the polyolefin, the dispersant, and the C5-C 26 -alkyl primary aliphatic amide. The concentration of the dispersant is preferably in the range from 4 or 9 or 15 weight percent to 50 or 40 or 30 weight percent, based on the weight of the polyolefin particles, the dispersant, and the C5-C 26 -alkyl aliphatic amide. The concentration of the C5-C 26 -alkyl primary aliphatic amide is preferably in the range 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.

[0015] The pH of the composition used to prepare the article can be adjusted to the desired level by adding a neutralizing agent such as KOH.

[0016] The composition advantageously contains C 10 ~C24 It further contains a stabilizing amount of an anionic surfactant such as a 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. The article is preferably prepared by applying the composition to a paper substrate using a drawdown bar and subsequently removing water at an elevated temperature, preferably as described in the following section.

[0017] 1 g / m 2 or 2 g / m 2 or 5 g / m 2 to 20 g / m 2 or 12 g / m 2 or 10 g / m 2 It has been discovered that coating weights in the range from 1 g / m to 20 g / m, or 2 g / m to 12 g / m, or 5 g / m to 10 g / m can be achieved with desirable water vapor transmission rate (MVTR) and coefficient of friction (CoF) characteristics.

[0018] Method for preparing a coated substrate and method for measuring coating weight UPM Brilliant 62 Glassine Paper (basis weight 62 g / m 2 ) was coated with a polyolefin dispersion using a drawdown bar and dried in a forced air oven at 100 °C for 2 minutes to a final coating surface density (coating weight) of 8 g / m 2 (~8 - 9 μm coating thickness). Coating weights were measured by punching holes in the coated and uncoated UPM papers with a circular die to form disks having a specific diameter (D cm). The coated disks (W1) were weighed against the uncoated disks (W2), and the coating weight was calculated by the following formula.

[0019]

Equation

[0020] 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 permeation 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.

[0021] 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 100 mm of the flat surface at a speed of 2.5 mm / s. The force Fd (unit: gram weight) reaching the plateau when the thread was moved steadily was recorded. The dynamic CoF was calculated as Fd / 200.

[0022] Measurement of Degree of Neutralization The degree of neutralization of the polyolefin dispersion was determined by the following formula.

[0023]

Number

Example

[0024] 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. Solids content refers to the solids weight % of polyolefin, dispersant, aliphatic amide, and anionic surfactant in the dispersion. PS refers to the particle size of the particles in micrometers determined by dynamic light scattering.

[0025] PL1280 refers to AFFINITY™ PL 1280 LLDPE ethylene-octene copolymer. V4200 refers to VERSIFY™ ethylene-propylene copolymer. N960 refers to NUCREL™ N960 ethylene-methacrylic acid copolymer. OA (oleamide, melting point 70 °C) is a C 18 -alkyl mono-unsaturated primary aliphatic amide. EA (erucamide, melting point 80 °C) is a C 22 -alkyl mono-unsaturated primary aliphatic amide. BA (behenamide, melting point 112 °C) is a C 22 -alkyl saturated primary aliphatic amide. EBS (ethylene bis-stearamide, melting point 145 °C) is a C 38 -alkyl secondary aliphatic amide. OPA (oleyl palmitamide, melting point 60 - 66 °C) is a C 34 -alkyl secondary aliphatic amide. SEA (stearyl erucamide (5uracamide), melting point 70 - 75 °C) is a C 40 -alkyl secondary aliphatic amide.

[0026] 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%.

[0027]

Table 1

[0028] General Procedure for Preparing a Polyolefin Dispersion That Is an Aqueous Dispersion The aqueous dispersion was prepared by the following general procedure. 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 that was an intermediate.

[0029] 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.

[0030] Each aqueous dispersion was taken out of 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).

[0031] 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.

[0032] [Table 2]

[0033] The data shows the improvement in MVTR of the coating containing primary aliphatic amide when compared to either a coating without amide additive or a coating containing secondary aliphatic amide. 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 An article comprising paper coated with a coating, the coating comprising poly-C ２ to C ３ -olefin, a dispersant, and C ５ to C ２６ -alkyl primary aliphatic amide, and the coating has a coating weight in the range of 1 g / m ２ to 20 g / m ２ of the article. Claim 2 The poly-C ２ -C ３ -olefin, the dispersant, and the C ５ -C ２６ -alkyl primary aliphatic amide, the concentration of the polyolefin is in the range of 40 to 95% by weight, the concentration of the dispersant is in the range of 4 to 50% by weight, and the C ５ -C ２６ -alkyl primary aliphatic amide is in the range of 0.5 to 5% by weight. The article according to claim 1 Claim 3 The dispersant is a salt of an ethylene-acrylic acid copolymer or a salt of an ethylene-methacrylic acid copolymer, and the C ５ to C ２６ -alkyl primary aliphatic amide is a C １０ to C ２４ -alkyl primary aliphatic amide, and the coating has a coating weight in the range of 5 g / m ２ to 10 g / m ２ The article according to claim 2, having. Claim 4 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 said poly-C ２ -C ３ -olefin is an ethylene-C ４ -C １０ -α-olefin copolymer. The article according to claim 3 Claim 5 The ethylene-C ４ -C １０ -α-olefin copolymer is an ethylene-1-octene copolymer, and the article according to claim 4. Claim 6 Said C １０ to C ２４ -alkyl primary aliphatic amide is a C １６ to C ２２ -alkyl primary aliphatic amide, and the poly-C ２ to C ３ -olefin is polypropylene, the article according to claim 3. Claim 7 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 is a poly(ethylene-propylene) copolymer. The article according to claim 3 Claim 8 The poly-C ２ -C ３ -olefin, the dispersant, and the C ５ -C ２６ -alkyl primary aliphatic amide, based on the weight of the poly-C ２ -C ３ -olefin concentration is in the range of 60 to 90% by weight, the dispersant concentration is in the range of 9 to 40% by weight, and the C ５ -C ２６ -alkyl primary aliphatic amide concentration is in the range of 1 to 4% by weight, the article according to claim 2. Claim 9 the poly-C ２ -C ３ -olefin, the dispersant, and the C １６ -C ２２ -alkyl primary aliphatic amide, based on the weight of the poly-C ２ -C ３ -olefin concentration is in the range of 60 to 90% by weight, the dispersant concentration is in the range of 9 to 40% by weight, and the C １６ -C ２２ -alkyl primary aliphatic amide concentration is in the range of 1 to 4% by weight, the article according to any one of claims 4 to 7.

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