Aqueous dispersions of polyisobutylene particles and polyolefin particles

Abstract

This invention describes an aqueous dispersion composition. The composition comprises an aqueous dispersion of the following particles: a) polyisobutylene particles; and b) polyolefin particles, wherein the polyolefin particles are polyethylene or polypropylene particles, and the weight-to-weight ratio of the polyisobutylene particles to the polypropylene particles is in the range of 20:80 to 80:20. This composition can be used to prepare coatings on paper or paperboard substrates, which exhibit excellent moisture barrier properties and tackiness.

Description

Background Technology

[0001] This invention relates to aqueous dispersions of polyisobutylene and various polyolefins. These dispersions can be used to improve the moisture barrier properties of paper and paperboard substrates.

[0002] Traditionally, paper or paperboard is given moisture-barrier properties by applying a coating (usually molten polyethylene) to a paper substrate, followed by cooling and calendering. Polyethylene offers advantages such as heat-sealability, flexibility, and complete hydrophobicity; however, although standard in industry, polyethylene-coated paper and paperboard have several drawbacks. First, a thick coating, typically about 1 mil (25 micrometers), needs to be applied to the substrate to achieve the desired moisture-barrier properties, provide adhesion to the substrate, and prevent film defects such as pinhole leakage. Alternatives to polyethylene, such as acrylic resins, do not provide acceptable moisture-barrier properties. Furthermore, unlike polyethylene, acrylic resins cannot be easily heat-sealed. Polyvinylidene chloride (PVDC) is another alternative that provides excellent moisture protection with a low coating weight, but it degrades at low temperatures, leading to contamination of recycled materials and causing corrosion and damage to material recycling equipment.

[0003] Therefore, in the paper and paperboard coating industry, achieving acceptable moisture barrier properties at a fraction of the currently required standard film thickness would be an advantage, not only saving on raw material costs but also making coated products suitable for recycling. Furthermore, the reduction in the weight of finished products (e.g., paper cups), even by only 2%, would have a significant impact on transportation costs. Summary of the Invention

[0004] In one aspect, the present invention addresses a need in the art by providing a composition comprising an aqueous dispersion of the following particles: a) polyisobutylene particles; and b) polyolefin particles, which are polyethylene or polypropylene particles; wherein the weight-to-weight ratio of the polyisobutylene particles to the polyolefin particles is in the range of 20:80 to 80:20; wherein the composition has a solids content derived from the polyisobutylene particles and the polyolefin particles in the range of 20% by weight to 60% by weight; wherein the polyisobutylene particles and the polyolefin particles have a density in the range of 0.1 μm to 12 μm. 90 granularity.

[0005] In a second aspect, the present invention is an article comprising a film attached to a paper or paperboard substrate, wherein the film comprises 20% to 80% by weight of a polyisobutylene polymer and 20% to 80% by weight of a polyolefin; wherein the film has a thickness in the range of about 3 μm to 20 μm. Detailed Implementation

[0006] In a first aspect, the present invention is a composition comprising an aqueous dispersion of the following particles: a) polyisobutylene particles; and b) polyolefin particles, wherein the polyolefin particles are polyethylene particles or polypropylene particles, wherein the weight-to-weight ratio of the polyisobutylene particles to the polyolefin particles is in the range of 20:80 to 80:20; wherein the combination of the polyisobutylene dispersion and the polyolefin dispersion has a solids content in the range of 20% by weight to 60% by weight based on water, the polyisobutylene, and the polyolefin; wherein the polyisobutylene particles and the polyolefin particles have a density in the range of 0.1 μm to 12 μm. 90 granularity.

[0007] Aqueous dispersions of polyisobutylene polymer particles and polyolefin polymer particles are advantageously prepared by blending aqueous dispersions of polyisobutylene polymer particles and polyolefin polymer particles. The aqueous dispersions of polyisobutylene polymer particles can be prepared by dispersing resinous, flowable polyisobutylene into water under high shear conditions in the presence of a suitable surfactant. As used herein, “polyisobutylene” refers to isobutylene homopolymers and copolymers comprising repeating units of isobutylene and comonomers, wherein the isobutylene repeating units form the majority of the copolymer. Examples of copolymers include poly(isobutylene-isoprene) and poly(isobutylene-succinic anhydride), and examples of commercially available polyisobutylene (also known as polyisobutenes) homopolymers and copolymers include Oppanol B10, Oppanol B12, Oppanol B15, Oppanol B100, and Oppanol B200 polyisobutylene; Glissopal V190, Glissopal V500, Glissopal V640, and Glissopal V1500 polyisobutylene; Vistanex LM-MH, Vistanex LM-MS, and LM-H polyisobutylene; Laxess X Butyl RB 100, Laxess X Butyl RB 101-3, and Laxess X Butyl RB 402 isobutylene-isoprene copolymer; and HRD-350, HRD-400, HRD-450, HRD-500, HRD-600, HRD-650 and HRD 950 polyisobutylene.

[0008] Examples of suitable surfactants include anionic surfactants such as alkali metal C8-C. 20 - Alkylbenzene sulfonates and sulfates, as well as nonionic surfactants such as secondary alcohol ethoxylates and C8-C 20--alkyl glucosides. Specific examples of suitable anionic surfactants include sodium dodecylbenzenesulfonate and sodium dodecylbenzene sulfate. Secondary alcohol ethoxylates can be characterized by the following formula:

[0009] C 10--15 H -22-32 O(CH2CH2O) x H

[0010] Where x ranges from 8 to 50, and O(CH2CH2O) x H group is bonded to C 10--15 H 22--32 chain

[0011] The CH group on the [top / off]. Preferably, the secondary alcohol ethoxylate is characterized by the following formula:

[0012] C 12--14 H 26--30 O(CH2CH2O) x H

[0013] Wherein x is preferably 10 to 50, more preferably 10 to 40. Examples of commercially available suitable surfactants include TERGITOL. TM 15-S-40, TERGITOL 15-S-20, and TERGITOL TMN-10 are secondary alcohol ethoxylated surfactants (trademarks of The Dow Chemical Company or its affiliates). Suitable alkyl glucosides include decyl glucoside, dodecyl glucoside, and lauryl glucoside.

[0014] The D of dispersed polyisobutylene polymer particles as determined using a dynamic light scattering particle size analyzer (e.g., a Beckman LS230 particle size analyzer) 90 The particle size is in the range of 0.1 μm, preferably 0.2 μm, more preferably 0.5 μm to 12 μm, preferably to 8 μm, more preferably to 4 μm, and most preferably to 2 μm.

[0015] Aqueous dispersions of polyolefin particles can be prepared by continuous twin-screw extrusion methods as described in US 8,318,257 and US 7,803,865. Dispersions of polyolefin polymer particles can be prepared by dispersing the polymer particles in the presence of a dispersant, neutralizer, and coupling agent, as described, for example, in US 10612913. The dispersant is preferably a copolymer comprising structural units of ethylene and carboxylic acid monomers (i.e., an ethylene-carboxylic acid copolymer), wherein the copolymer has a melt flow index in the range of 50 g / 10 min to 2000 g / 10 min, and the weight-to-weight ratio of the structural units of ethylene monomers to carboxylic acid monomers is in the range of 95:5 to 70:30. The melt flow index range is determined by ASTM 1238 at a temperature of 190°C and a load weight of 2.16 kg.

[0016] As used herein, suitable polyolefin particles have a wide molecular weight range, but do not include polyolefin waxes, which can be described by the following formula:

[0017] H-(CH2CHR) x -H

[0018] Where R is H or CH3, and x is in the range of 72 to 360.

[0019] The neutralizing agent can be an inorganic or organic base. Examples of suitable inorganic bases include ammonia, potassium hydroxide, sodium hydroxide, and calcium hydroxide; examples of suitable organic bases include N,N-dimethylethanolamine (DMEA), diethylamine, and morpholine. The concentration of the neutralizing agent is preferably high enough to neutralize at least half of the carboxylic acid groups in the dispersion. For example, if the dispersion contains 0.05 mol of carboxylic acid groups by a given mass, at least 0.025 mol of a neutralizing agent such as N,N-dimethylethanolamine will be required. Therefore, the ratio of basic functional groups (preferably amine groups or ammonia) in the neutralizing agent to carboxylic acid groups in the dispersion is preferably at least 0.5:1. Compositions prepared with a dispersant and a neutralizing agent will contain the neutralizing agent or a salt thereof, or a combination thereof.

[0020] Coupling agents may be included to improve the compatibility between the dispersant and the polyolefin. Examples of suitable coupling agents include ethylene-co-maleic anhydride, which, when used, is present at a concentration ranging from 5% to 20% by weight, more preferably up to 10% by weight, based on the weight of the polyolefin, dispersant, and coupling agent.

[0021] The D90 particle size of the dispersed polyolefin particles was also determined using a dynamic light scattering particle size analyzer, and was within the range of 0.1 μm, preferably 0.2 μm, more preferably 0.5 μm, up to 12 μm, preferably up to 8 μm, more preferably up to 4 μm, and most preferably up to 2 μm.

[0022] Polyolefin dispersions are either polypropylene dispersions or polyethylene dispersions. As used herein, “polyethylene” refers to linear low-density polyethylene; low-density polyethylene; high-density polyethylene; ethylene-olefin copolymers, such as ethylene-co-octene copolymers, ethylene-co-hexene copolymers, or ethylene-propylene copolymers; ethylene-carboxylic acid ester copolymers, such as ethylene-methyl acrylate copolymers or ethylene-ethyl acrylate copolymers; ethylene-carboxylic acid copolymers, such as ethylene-methacrylic acid; and combinations thereof. (A polyethylene-carboxylic acid copolymer with an acid value less than 90 mg KOH / g is considered polyethylene.)

[0023] Commercial examples of waterborne polyethylene dispersions include CANVERA. TM 1110 polyolefin dispersion, HYPOD TM 2000 polyolefin dispersion and RHOBARR TM 320 Polyolefin Elastomer Dispersion. (CANVERA, HYPOD, and RHOBARR are trademarks of The Dow Chemical Company or its affiliates.)

[0024] As used herein, polypropylene refers to polypropylene homopolymers and copolymers comprising repeating units of polypropylene and comonomers, wherein the repeating polypropylene units form the majority of the copolymer.

[0025] The weight ratio of polyisobutylene polymer particles to polyolefin polymer particles (preferably polyethylene polymer particles) is preferably in the range of 25:75 to 70:30, more preferably in the range of 65:35.

[0026] After the dispersions are combined, the composition can be applied to paper or paperboard using a wire-wound doctor blade. The wet film is advantageously heated to remove water and form a dry coating, preferably to a temperature in the range of 50°C, more preferably from 70°C to 150°C, more preferably 120°C, to provide a final dry film with a thickness in the range of 3 μm, preferably from 6 μm, and more preferably from 8 μm to 20 μm, preferably up to 16 μm, and more preferably up to 12 μm.

[0027] In another aspect, the present invention is an article comprising a film attached to a paper or paperboard substrate, wherein the film comprises 20% to 80% by weight of a polyisobutylene polymer and 20% to 80% by weight of a polyolefin, said polyolefin being polyethylene or polypropylene, and wherein the film has a thickness in the range of about 4 μm to 20 μm. Preferably, the film comprises a polyisobutylene polymer and polyethylene as defined above. The weight-to-weight ratio of the polyisobutylene polymer to the polyolefin polymer (preferably a polyethylene polymer) in the film is preferably in the range of 25:75 to 70:30, more preferably to 65:35.

[0028] The weight density of paper or paperboard is 40 g / m³ 2 Up to 350g / m 2 Within this range. For paper, a preferred weight density is 60 g / m³. 2 Up to 100g / m 2 Within the range; for paperboard, a preferred weight density is 200 g / m³. 2 Up to 300g / m 2 Within the specified range. The paper or paperboard may be uncoated or pre-coated to create a smooth surface before applying the coating formulation.

[0029] It has been found that thin coatings of polyisobutylene-polyolefin films on paper or paperboard substrates impart desired moisture barrier properties as well as acceptable low levels of tack. The coated substrates are suitable for packaging applications requiring a relatively low ratio of coated resin to substrate weight for recycling purposes.

[0030] Example

[0031] Example 1 - Preparation of polyisobutylene resin dispersion A (PIBD-A)

[0032] HRD-400 polyisobutylene resin (50g, provided by Shandong Hongrui New Material Technology Co., Inc.) and TERGITOL were used. TM TMN-10 dispersant (2.8 g, 90% active) and water (2.2 g) were combined and mixed at 3500 rpm for 4 minutes using a FlackTek SpeedMixer DAC 150.1 FV-K. Then, an additional 45 g of water was gradually added under stirring to form a D-type dispersion with 50% solids content and a particle size of 1.13 μm. 90 Aqueous polyisobutylene (PIB) dispersion with particle size.

[0033] Example 2 - Preparation of polyisobutylene resin dispersion B (PIBD-B)

[0034] HRD-400 polyisobutylene (50g), TERGITOL TM 15-S-9 dispersant (2.5 g) and water (2.5 g) were combined and mixed at 3500 rpm for 4 minutes using a FlackTek SpeedMixer DAC 150.1 FV-K. Then, an additional 45 g of water was gradually added under stirring to form a D-type dispersant with 50% solids and a particle size of 1.03 μm. 90 Aqueous PIB dispersions with particle size distribution.

[0035] Example 3 - Preparation of polyisobutylene resin dispersion C (PIBD-C)

[0036] HRD-400 polyisobutylene resin (50 g) and Plantacare 2000UP decyl glucoside (5 g, 50% active, supplied by BASF) were combined and mixed at 3500 rpm for 4 minutes using a FlackTek SpeedMixer DAC 150.1FV-K. Then, an additional 45 g of water was gradually added under stirring to form a D-type polymer with 50% solids content and a particle size of 1.02 μm. 90 Aqueous PIB dispersions with particle size distribution.

[0037] Example 4 - Preparation of polyisobutylene resin dispersion D (PIBD-D)

[0038] HRD-400 polyisobutylene resin (50 g) and DS-4 sodium dodecylbenzenesulfonate (5 g, 23% active) were combined and mixed at 3500 rpm for 4 minutes using a FlackTek SpeedMixer DAC 150.1FV-K. Then, an additional 45 g of water was gradually added under stirring to form a D-type resin with 50% solids content and a particle size of 0.87 μm. 90 Aqueous PIB dispersions with particle size distribution.

[0039] CANVERA 1110 polyolefin dispersion (CANV, 43% solids) or RHOBARR 320 polyolefin dispersion (RHOB, 43% solids) was combined with the PIB dispersion at ambient temperature to form the compositions described in Table 1. All amounts listed are in grams of total dispersion without adjusted solids content.

[0040] Table 1 - Coating Compositions

[0041] Example number PIBD-A PIBD-B PIBD-C PIBD-D CANV RHOB Comparative Example 1 10 Comparative Example 2 10 Comparative Example 3 8.6 Example 1 8.6 10 Example 2 8.6 10 Example 3 8.6 10 Example 4 8.6 10 Example 5 8.6 10 Example 6 8.6 10 Example 7 8.6 10 Example 8 8.6 10 Example 9 2.2 10 Example 10 3.7 10 Example 11 5.7 10 Example 12 12.9 10 Example 13 20.1 10 Example 14 34.4 10 Example 15 77.4 10

[0042] The coating formulation was prepared by blending components at room temperature. The blend was then coated onto paper (60 g / m²) using a Mayer bar automated coating apparatus. 2 The coated film was dried at 100°C for 2 minutes, and the dry film thickness was controlled to be 10±2μm.

[0043] Table 2 shows the moisture vapor transmission rate (WVTR) performance at 38°C and 90% relative humidity. WVTR was measured using a MOCONTRAN Model 3 / 33 permeameter at 38°C and 90% relative humidity according to ASTM D3985-02. Comparative Example 3 is a pure PIB dispersion. Membrane viscosity was evaluated using a PT-1000 probe viscosity tester with a probe speed of 0.5 cm / s and a residence time of 1 s. WVTR is expressed in g / m³. 2•Measured daily. WVTR reduction refers to the percentage reduction in WVTR of the coatings from the PB / PE blend relative to the coatings from the corresponding unblended PE dispersions in Comparative Examples 1, 2, and 4.

[0044] Table 2 – WVTR Performance

[0045] Example number WVTR WVTR decreases Comparative Example 1 104.2 N / A Comparative Example 2 148.6 N / A Comparative Example 3 25.8 N / A Comparative Example 4 223.7 N / A Example 1 40.8 60.8％ Example 2 77.6 25.6％ Example 3 44.0 57.8％ Example 4 79.9 23.3％ Example 5 60.0 59.6％ Example 6 82.7 44.3％ Example 7 80.9 45.5％ Example 8 78.1 47.4％

[0046] Data indicate that coatings formed solely from polyethylene dispersions exhibit poor WVTR (>100 g / m³). 2 (·day). Conversely, coatings prepared using only PIB dispersions or blends of PIB and PE dispersions achieve less than 100 g / m³. 2 • WVTR per day. However, as shown in Table 3, a proper balance between WVTR and probe tack requires a coating formed from the blend. Probe tack is measured in grams. Low tack is essential for paper coating applications.

[0047] Table 3 - WVTR and probe tack of coatings from CANVERA and PIBD-A

[0048]

[0049]

[0050] The coating produced by blends of PIBD-A and CANVERA 1110 polyolefin dispersion (a dispersion of high-density polyethylene) exhibits excellent tack and WVTR properties over a wide range. In contrast, the coating produced by PIBD-A yields only poor tack (>4.5 g).

Claims

1. A coating composition comprising an aqueous dispersion of the following particles: a) polyisobutylene particles; and b) polyolefin particles, wherein the polyolefin particles are polyethylene particles or polypropylene particles, wherein the weight-to-weight ratio of the polyisobutylene particles to the polyolefin particles is in the range of 40:60 to 80:20; wherein the composition has a solids content derived from the polyisobutylene particles and the polyolefin particles in the range of 20% to 60% by weight; wherein the polyisobutylene particles and the polyolefin particles have a density in the range of 0.1 μm to 12 μm. 90 granularity.

2. The composition according to claim 1, wherein the polyolefin particles are polyethylene particles; Furthermore, the polyisobutylene particles are polyisobutylene homopolymer particles.

3. The composition according to claim 2, wherein the polyisobutylene particles and the polyethylene particles have a density (D) in the range of 0.5 μm to 4 μm. 90 granularity.

4. The composition according to claim 3, wherein the weight ratio of the polyisobutylene polymer particles to the polyethylene polymer particles is in the range of 40:60 to 65:

35.

5. The composition of claim 2, wherein the polyethylene particles comprise high-density polyethylene.

6. The composition of claim 2, wherein the polyethylene particles comprise an ethylene-co-octene copolymer or an ethylene-ethyl acrylate copolymer or a combination thereof.

7. The composition according to claim 3, wherein the composition further comprises a dispersant, a coupling agent, a neutralizing agent or a salt of a neutralizing agent; or a combination thereof.

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