Aqueous dispersions of polyisobutylene and polyolefin particles

Abstract

An aqueous dispersion composition is described that includes an aqueous dispersion of a) polyisobutylene particles and b) polyolefin particles that are polyethylene or polypropylene particles, wherein the weight to weight ratio of the polyisobutylene particles to the polypropylene particles is in the range of 20:80 to 80:20. The composition is useful for making coated paper or paperboard substrates that have excellent moisture barrier and adhesion properties.

Description

[Background technology]

[0001] The present invention relates to aqueous dispersions of polyisobutylene and different polyolefins, which are useful for improving the vapor barrier properties of paper and paperboard substrates.

[0002] Moisture barrier properties have traditionally been imparted to paper or paperboard by applying a coating, usually molten polyethylene, to the paper substrate, followed by cooling and calendering. Polyethylene has the advantages of being heat-sealable, flexible, and omniphobic. Nevertheless, although standard in the industry, polyethylene-coated paper and paperboard have several drawbacks. First, a thick coating, typically about 1 mil (25 microns), must be applied to the substrate to achieve the desired moisture barrier properties, provide adhesion to the substrate, and avoid film defects such as pinhole leaks. Alternatives to polyethylene, such as acrylic, do not provide acceptable moisture barrier properties. Furthermore, unlike polyethylene, acrylic is not easily heat-sealable. Polyvinylidene chloride (PVDC) is another alternative, which provides excellent moisture barrier properties at low coat weights but decomposes at low temperatures, causing contamination of recyclables and corrosion and damage to material recycling equipment.

[0003] Therefore, it would be advantageous in the art of paper and paperboard coatings to achieve acceptable moisture barrier properties at a fraction of the standard film thickness required today, not only to save on raw material costs but also to make the coated product suitable for recycling. Furthermore, a reduction in the weight of the final article (e.g., a paper cup), even by as little as 2 percent by weight, has a noticeable impact on shipping costs. Summary of the Invention

[0004] In one aspect, the present invention provides a composition comprising an aqueous dispersion of a) polyisobutylene particles and b) polyolefin particles, which are polyethylene or polypropylene particles, wherein a weight to weight ratio of the polyisobutylene particles to the polyolefin particles is in the range of 20:80 to 80:20, the composition having a solids content resulting from the polyisobutylene particles and the polyolefin particles in the range of 20 to 60 weight percent, and the polyisobutylene particles and the polyolefin particles having a D 90 The present invention addresses a need in the art by providing a composition having a particle size.

[0005] In a second aspect, the invention is an article comprising a film applied to a paper or paperboard substrate, the film comprising 20 to 80 weight percent polyisobutylene polymer and 20 to 80 weight percent polyolefin, the film having a thickness in the range of about 3 μm to 20 μm. DETAILED DESCRIPTION OF THE INVENTION

[0006] In a first aspect, the present invention provides a composition comprising an aqueous dispersion of 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, the dispersion of the polyisobutylene and polyolefin combination having a solids content in the range of 20 to 60 weight percent, based on the weight of the water, polyisobutylene, and polyolefin, and the polyisobutylene and polyolefin particles have a D 90 It has a particle size.

[0007] The aqueous dispersion of polyisobutylene and polyolefin polymer particles is advantageously prepared by blending an aqueous dispersion of polyisobutylene polymer particles with an aqueous dispersion of polyolefin polymer particles. The aqueous dispersion of polyisobutylene polymer particles may be prepared by dispersing resinous, flowable polyisobutylene in 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 a comonomer, with the isobutylene repeating units forming the majority of the copolymer. Examples of copolymers include poly(isobutylene-isoprene) and poly(isobutylene-succinic anhydride), and examples of commercially available polyisobutylene (also called polyisobutene) homopolymers and copolymers include Oppanol B10, Oppanol B12, Oppanol B15, Oppanol B100, and Oppanol B200 polyisobutylenes; Glissopal V190, Glissopal V500, Glissopal V640, and Glissopal V1500 polyisobutenes; Vistanex LM-MH, Vistanex LM-MS, LM-H polyisobutenes; 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 alkali metal C8-C 20 - anionic surfactants such as alkyl benzene sulfonates and sulfates, as well as secondary alcohol ethoxylates and C8-C 20 -alkyl glucosides and other nonionic surfactants. Specific examples of suitable anionic surfactants include sodium dodecylbenzenesulfonate and sodium dodecylbenzenesulfonate. Secondary alcohol ethoxylates are compounds of the following formula: C10~15 H -22~32 O(CH2CH2O) x H where x is 8 to 50 and O(CH2CH2O) x H group is C 10~15 H 22~32 Preferably, the secondary alcohol ethoxylate has the formula: C 12~14 H 26~30 O(CH2CH2O) x H where x is preferably 10 to 50, preferably 10 to 40. Commercially available examples of suitable surfactants include TERGITOL™ 15-S-40, TERGITOL 15-S-20, and TERGITOL TMN-10 secondary alcohol ethoxylate surfactant (trademarks of The Dow Chemical Company or its affiliates). Suitable alkyl glucosides include decyl glucoside, dodecyl glucoside, and lauryl glucoside.

[0009] D of dispersed polyisobutylene polymer particles 90 The particle size, as determined using a dynamic light scattering particle size analyzer (e.g., a Beckman LS230 Particle Size Analyzer), is in the range of from 0.1 μm, preferably from 0.2 μm, more preferably from 0.5 μm, to 12 μm, preferably to 8 μm, more preferably to 4 μm, and most preferably to 2 μm.

[0010] Aqueous dispersions of polyolefin particles may be prepared by a continuous twin-screw extrusion process, such as those described in U.S. Patent Nos. 8,318,257 and 7,803,865. Dispersions of polyolefin polymer particles may be prepared by dispersing polymer particles in the presence of a dispersant, a neutralizing agent, and a coupling agent, as described, for example, in U.S. Patent No. 10,612,913. The dispersant is preferably a copolymer (i.e., an ethylene-carboxylic acid copolymer) containing ethylene structural units and carboxylic acid monomer structural units, the copolymer having a melt flow index ranging from 50 g / 10 min to 2000 g / 10 min, and the weight-to-weight ratio of ethylene structural units to carboxylic acid monomer structural units ranging from 95:5 to 70:30. The melt flow index range is determined according to ASTM 1238 at a temperature of 190°C and a load of 2.16 kg.

[0011] As used herein, suitable polyolefin particles have a broad molecular weight range but do not include polyolefin waxes, which have the following formula: H-(CHCHR) x -H where R is H or CH3 and x ranges from 72 to 360.

[0012] The neutralizing agent may be an inorganic or organic base. Examples of suitable inorganic bases include ammonia, potassium hydroxide, sodium hydroxide, and calcium hydroxide, while examples of suitable organic bases include N,N-dimethylethanolamine, 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 dispersant. For example, if the dispersant contains 0.05 moles of carboxylic acid groups, at least 0.025 moles of a neutralizing agent such as N,N-dimethylethanolamine would be required. Therefore, the ratio of base functional groups, preferably amine groups or ammonia, in the neutralizing agent to carboxylic acid groups in the dispersant is preferably at least 0.5:1. The composition prepared using the dispersant and neutralizing agent includes the neutralizing agent, or a salt thereof, or a combination thereof.

[0013] A coupling agent may be included to improve compatibility between the dispersant and the polyolefin. One example of a suitable coupling agent is ethylene-co-maleic anhydride, which, if used, is present in a concentration ranging from 5 to 20 weight percent, more preferably up to 10 weight percent, based on the weight of the polyolefin, dispersant, and coupling agent.

[0014] Dispersed polyolefin particles D 90 The particle size, also determined using a dynamic light scattering particle size analyzer, is in the range of from 0.1 μm, preferably from 0.2 μm, more preferably from 0.5 μm, to 12 μm, preferably to 8 μm, more preferably to 4 μm, and most preferably to 2 μm.

[0015] The polyolefin dispersion is a polypropylene dispersion or a polyethylene dispersion. As used herein, "polyethylene" refers to linear low-density polyethylene; low-density polyethylene; high-density polyethylene; ethylene-alkene copolymers such as ethylene-co-octene copolymer, ethylene-co-hexene copolymer, or ethylene-propylene copolymer; ethylene-carboxylic acid ester copolymers such as ethylene-methyl acrylate copolymer or ethylene-ethyl acrylate copolymer, and ethylene-carboxylic acid copolymers such as ethylene-methacrylic acid; and combinations thereof. (A polyethylene-carboxylic acid copolymer is considered to be polyethylene if it has an acid value of less than 90 mg KOH / g.)

[0016] Commercially available examples of aqueous polyethylene dispersions include CANVERA™ 1110 polyolefin dispersion, HYPOD™ 2000 polyolefin dispersion, and RHOBARR™ 320 polyolefin elastomer dispersion. (CANVERA, HYPOD, and RHOBARR are trademarks of The Dow Chemical Company or its affiliates.)

[0017] As used herein, polypropylene refers to polypropylene homopolymer and copolymers comprising repeat units of polypropylene and a comonomer, with the polypropylene repeat units forming the majority of the copolymer.

[0018] The weight to weight ratio of polyisobutylene polymer particles to polyolefin polymer particles, preferably polyethylene polymer particles, is preferably in the range of from 25:75 to 70:30, more preferably up to 65:35.

[0019] After the dispersions are combined, the composition can be applied to paper or paperboard using a wire-wound drawdown bar. Advantageously, the wet film is heated to a temperature preferably in the range of 50°C, more preferably 70°C to preferably 150°C, more preferably 120°C to remove water and form a dry coating, providing a final dry film having a thickness in the range of 3 μm, preferably 6 μm, more preferably 8 μm to 20 μm, preferably 16 μm, more preferably 12 μm.

[0020] In another aspect, the invention is an article comprising a film applied to a paper or paperboard substrate, the film comprising 20 to 80 weight percent polyisobutylene polymer and 20 to 80 weight percent polyolefin, which is polyethylene or polypropylene, the film having a thickness in the range of about 4 μm to 20 μm. Preferably, the film comprises polyisobutylene polymer and polyethylene as defined hereinabove. The weight-to-weight ratio of polyisobutylene polymer to polyolefin polymer, preferably polyethylene polymer, in the film is preferably in the range of 25:75 to 70:30, more preferably up to 65:35.

[0021] The weight density of the paper or paperboard is 40 g / m 2 ~350g / m 2 For paper, the preferred weight density is in the range of 60 g / m 2 ~100g / m 2 and for paperboard, the preferred weight density is in the range of 200 g / m 2 ~300g / m 2 The paper or paperboard may be uncoated or may be pre-coated to produce a smooth surface prior to application of the coating formulation.

[0022] It has been discovered that thin coatings of polyisobutylene-polyolefin films on paper or paperboard substrates provide desirable vapor barrier properties combined with an acceptably low level of tack. The coated substrates are suitable for packaging applications requiring a relatively low ratio of coated resin to substrate weight for recycling purposes. [Example]

[0023] Example 1 - Preparation of Polyisobutylene Resin Dispersion A (PIBD (Polyisobutylene Resin Dispersion)-A) HRD-400 polyisobutylene resin (50 g, supplied by Shandong Hongrui New Material Technology Co., Inc.), TERGITOL™ TMN-10 dispersion (2.8 g, 90% active ingredient), and water (2.2 g) were combined and mixed for 4 minutes at 3500 rpm using a FlackTek SpeedMixer DAC 150.1 FV-K. Additional water (45 g) was then added gradually with stirring to a final mixture with a 50% solids content and a D of 1.13 μm. 90 An aqueous polyisobutylene (PIB) dispersion having particle size was formed.

[0024] Example 2 - Preparation of Polyisobutylene Resin Dispersion B (PIBD-B) HRD-400 polyisobutylene resin (50 g), TERGITOL™ 15-s-9 dispersion (2.5 g), and water (2.5 g) were combined and mixed for 4 minutes at 3500 rpm using a FlackTek SpeedMixer DAC 150.1 FV-K. Additional water (45 g) was then added slowly with stirring to produce a mixture with 50% solids and a D of 1.03 μm. 90 An aqueous PIB dispersion having particle sizes was formed.

[0025] Example 3 - Preparation of Polyisobutylene Resin Dispersion C (PIBD-C) HRD-400 polyisobutylene resin (50 g) and Plantacare 2000UP decyl glucoside (5 g, 50% active ingredient, supplied by BASF) were combined and mixed for 4 minutes at 3500 rpm using a FlackTek SpeedMixer DAC 150.1 FV-K. Additional water (45 g) was then added gradually with stirring to a final solids content of 50% and a D of 1.02 μm. 90 An aqueous PIB dispersion having particle sizes was formed.

[0026] Example 4 - Preparation of Polyisobutylene Resin Dispersion D (PIBD-D) HRD-400 polyisobutylene resin (50 g) and DS-4 sodium dodecylbenzene sulfonate (5 g, 23% active ingredient) were combined and mixed for 4 minutes at 3500 rpm using a FlackTek SpeedMixer DAC 150.1 FV-K. Additional water (45 g) was then added gradually with stirring to a final solids content of 50% and a D of 0.87 μm. 90 An aqueous PIB dispersion having particle sizes was formed.

[0027] 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 listed in Table 1. All amounts listed are grams of total dispersion unadjusted for solids content. [Table 1]

[0028] The coating formulation was prepared by blending the ingredients at room temperature. The blend was wire bar coated onto a paper sheet (60 g / m) using a Meyer bar automatic film coating device. 2 The coated film was dried at 100°C for 2 minutes, and the thickness of the dried film was controlled to 10±2 μm.

[0029] Table 2 shows the water vapor transmission rate (WVTR) performance at 38°C and 90% relative humidity. WVTR was measured according to ASTM D3985-02 at 38°C and 90% relative humidity using a MOCON TRAN Model 3 / 33 Permeation Analyzer. Comparative Example 3 is a pure PIB dispersion. Film tack was evaluated using a PT-1000 probe tack tester at a probe speed of 0.5 cm / sec and a dwell time of 1 second. WVTR is reported in g / m 2 WVTR reduction refers to the percent reduction in WVTR of coatings from PB / PE blends relative to coatings from the corresponding unblended PE dispersions in Comparative Examples 1, 2, and 4. [Table 2]

[0030] The data show that coatings formed from polyethylene dispersions alone exhibit poor WVTR (100 g / m 2 In contrast, 100g / m 2 WVTRs of less than 10 days have been achieved using coatings prepared from PIB dispersions alone or blends of PIB and PE dispersions. However, as Table 3 shows, a suitable balance of WVTR and probe tack requires coatings formed from blends. Probe tack is measured in grams. Low tack is necessary for paper coating applications. [Table 3]

[0031] Coatings made from blends of PIBD-A and CANVERA 1110 polyolefin dispersion, a dispersion of high density polyethylene, provided excellent adhesion and WVTR performance over a wide range. In contrast, coatings made from PIBD-A alone provided poor adhesion (above 4.5 g).

Claims

1. A composition comprising an aqueous dispersion of a) polyisobutylene homopolymer particles and b) polyethylene particles, a weight to weight ratio of the polyisobutylene homopolymer particles to the polyethylene particles in the range of 20:80 to 80:20; 1. A composition having a solids content resulting from particles of the polyisobutylene homopolymer and the polyethylene in the range of 20 to 60 weight percent, the polyisobutylene homopolymer particles and the polyethylene particles having a D90 particle size in the range of 0.1 μm to 12 μm.

2. 10. The composition of claim 1, wherein the particles of polyisobutylene homopolymer and polyethylene have a D90 particle size in the range of 0.5 μm to 4 μm.

3. The composition of claim 1, wherein the weight-to-weight ratio of the polyisobutylene homopolymer particles to the polyethylene polymer particles is in the range of 25:75 to 65:

35.

4. The composition of claim 1 , wherein the polyethylene polymer particles comprise high density polyethylene.

5. 10. The composition of claim 1, wherein the polyethylene polymer particles comprise an ethylene-co-octene copolymer or an ethylene-ethyl acrylate copolymer, or a combination thereof.

6. The composition of claim 1 further comprising a dispersing agent, a coupling agent, a neutralizing agent, or a salt of a neutralizing agent, or a combination thereof.

Images