阅读说明：本技术 包含纳米纤维素的柔性包装膜 (Flexible packaging film comprising nanocellulose ) 是由 S·达斯 T·S·库鲁甘蒂 S·T·姆哈斯克 P·N·谢斯 于 2019-09-17 设计创作，主要内容包括：本发明涉及包含纳米纤维素的聚合物组合物,包含由所述聚合物组合物形成的一个或多个层的膜,以及其包装。本发明的一个目的是提供重量轻的、有成本效益的且可持续性的聚合物组合物和由其制成的膜。本发明的另一个目的是提供具有改进的热性能和机械性能的单材料膜。本发明人已经令人惊讶地发现,包含具有特定长宽比的纳米晶体纤维素的膜提供了改善的功能性能,如热性能和机械性能,并且进一步地,所述膜更好地适于回收。进一步优选地发现,包含聚烯烃(更优选聚乙烯)与具有特定长宽比的纳米晶体纤维素组合的膜提供了改善的功能性能,如热性能和机械性能,其适于包装家庭护理和个人护理产品。(The present invention relates to a polymer composition comprising nanocellulose, a film comprising one or more layers formed from said polymer composition, and packaging thereof. It is an object of the present invention to provide a polymer composition and films made therefrom that is lightweight, cost effective and sustainable. It is another object of the present invention to provide a single material film having improved thermal and mechanical properties. The inventors have surprisingly found that a film comprising nanocrystalline cellulose having a specific aspect ratio provides improved functional properties, such as thermal and mechanical properties, and further that the film is better suited for recycling. It has further preferably been found that films comprising a polyolefin, more preferably polyethylene, in combination with nanocrystalline cellulose having a specific aspect ratio provide improved functional properties, such as thermal and mechanical properties, which are suitable for packaging home care and personal care products.)

1. A polymer composition comprising:

i. a thermoplastic polymer;

nanocrystalline cellulose; and

(ii) a compatibilizing agent, which is selected from the group consisting of,

wherein the nanocrystalline cellulose has an aspect ratio of 1:1 to 1: 4.

2. The composition of claim 1, wherein the nanocrystalline cellulose has a number average particle size of 25nm to 600 nm.

3. The composition of claim 1 or 2, wherein the compatibilizer is selected from the group consisting of ethylene vinyl acetate copolymer (EVA), styrene-butadiene-styrene block copolymer (SBS), Ethylene Acrylic Acid (EAA), copolymers of polyethylene and maleic anhydride, and combinations thereof.

4. The composition according to any one of the preceding claims 1 to 3, wherein the thermoplastic polymer is selected from polyolefins, preferably from low density polyethylene, high density polyethylene, linear low density polyethylene, polyolefin elastomers, copolymers of ethylene and vinyl acetate, and polyesters.

5. The composition according to any one of the preceding claims 1 to 4, wherein the nanocrystalline cellulose is surface-modified, preferably treated with sulfur.

6. The composition of any preceding claim 1 to 5, wherein the composition comprises a wetting dispersant.

7. The composition of any preceding claim 1 to 6, wherein the wetting dispersant is a blend of fatty acid ester copolymers having acidic groups.

8. A monolayer film comprising the polymer composition of any of the preceding claims 1 to 7.

9. A multilayer film wherein at least one layer comprises the polymer composition according to any one of the preceding claims 1 to 7.

10. The film according to any one of claims 8 or 9, wherein the film comprises from 50 to 97 wt% of a polyolefin, preferably polyethylene, based on the total weight of the film.

11. The film according to any one of claims 8 to 10, wherein the film comprises from 0.5 to 5 wt% nanocrystalline cellulose, based on the total weight of the film.

12. The film according to any one of claims 8 to 11, wherein the film comprises 0.5 to 5 wt% of a compatibilizing agent, based on the total weight of the film.

13. The film according to any one of claims 8 to 12, wherein the film comprises from 0.5 to 5 wt.% of wetting dispersant, based on the total weight of the film.

14. A flexible package comprising the film of any one of claims 8 to 13.

15. A process for preparing a polymer composition according to any one of the preceding claims 1 to 7, comprising the steps of:

i. providing a thermoplastic polymer;

providing nanocrystalline cellulose in solid agglomerated form having a spherical diameter of 4 to 40 microns, more preferably 14 to 16 microns;

providing a compatibilizing agent;

at a temperature in the range of from 130 ℃ to 210 ℃ in a range of from 785 to 12560s^-1Combining the thermoplastic polymer, nanocrystalline cellulose, compatibilizer, preferably produced by a screw having a compression ratio of 1.5 to 1.8 and a screw rotation of preferably 40 to 60 nm;

v. providing a polymer composition, wherein the crystalline cellulose is modified in situ to provide a thermoplastic polymer matrix of nanocrystalline cellulose having an aspect ratio of 1:1 to 1: 4.

Technical Field

The present invention relates to polymer compositions comprising nanocellulose, films and containers comprising one or more layers formed from the polymer compositions, and packaging thereof.

Background

Plastics and articles containing plastics are widely used for packaging products having an inherently short life, such as personal care products and home care products. Although some of the plastic is recycled, most of it is disposed of in landfills. The handling and recycling of plastic-containing articles is of particular importance for environmental and economic reasons.

Polymer-based multilayer packaging materials are often used to combine the respective properties of different polymers. The multi-layer packaging material allows the package to perform a combination of functions not possible with a single layer and provides greater flexibility in package design. The multilayer packaging material also reduces the cost and reduces the amount of polymer material required compared to a single layer material performing the same function. In this way, the concept of customized packaging functionality is created to adequately protect sensitive products and achieve extended shelf life. For example, in printed packaging films, polyolefins such as Polyethylene (PE) or polypropylene (PP) are often combined with polyethylene terephthalate (PET), and in such multilayer films, the polyethylene terephthalate (PET) layer is suitable for printing, and the PE layer provides excellent sealing properties.

However, due to their poor recyclability, most multilayer films are typically incinerated or landfilled, which offsets efforts toward recycling economy and crude oil independence. Currently, there is a trend to replace multilayer packages with different types of polymeric materials with film laminates or multilayer films made from a single type of polymeric material. Film laminates or multilayer films having a single material, such as a polyolefin, and a small amount of other polymeric material are still considered films made of a single material and are relatively easy to recycle.

The inclusion of biomaterials in combination with synthetic thermoplastic polymers in the composition overcomes to some extent the problems of long-term environmental pollution and high raw material costs associated with the use of synthetic thermoplastics. One such biological material of interest is nanocellulose, including nanocrystalline cellulose, cellulose nanofibers, whiskers, and microfibrillated cellulose.

Dispersing nanocellulose in polymer compositions has proven to be very challenging. Attempts to disperse nanocellulose in polymer compositions have involved modifying the nanocellulose surface, which improves dispersion to some extent, but has not completely solved the dispersion problem, as such surface-modified nanocellulose fibrils may still tend to agglomerate when blended with the polymer. The dispersion problem is even more pronounced when the nanocellulose fibrils are prepared as a 2% dispersion or gel in water and it is desired to replace the water with some material that is more compatible with the thermoplastic polymer composition. Natural nanocellulose tends to form agglomerates in the polymer composition due to poor compatibility between nanocellulose and thermoplastic polymers and creates a weakness that reduces the mechanical properties of films made from the polymer composition.

Compatibilizers have been used in the past to improve the dispersion of nanocellulose in polymer compositions. Compatibilization is the process of adding substances to immiscible blends of polymers to increase their stability. The polymer compositions often include unstable phase morphology, resulting in poor mechanical properties. Compatibilization of the system will produce a more stable and better miscible phase morphology by creating interactions between the two otherwise immiscible (or partially miscible) polymers.

One such attempt to compatibilize nanocellulose and polymers was made in WO2017/049021a1(API IP HOLDING LLC), which discloses a polymer composite with a polymer, nanocellulose and a compatibilizer. The nanocellulose comprises cellulose nanocrystals and/or cellulose nanofibrils, and the compatibilizing agent comprises a maleated polymer.

More recently, WO2017/192838a1(Dow Global Technologies LLC) discloses a polymer blend comprising polyethylene and nanocellulose, which provides improved properties when compared to a polymer blend without nanocellulose. The average particle diameter of the nanocrystalline cellulose is 4 to 5 nanometers in width and 50 to 500 nanometers in length. It also discloses monolayer and multilayer films comprising the polymer blend.

It is still desirable to disperse the nanocellulose uniformly in the polymer matrix.

It is therefore an object of the present invention to provide a polymer composition and films made therefrom that is lightweight, cost effective and sustainable.

It is another object of the invention to provide a single material film having improved thermal and mechanical properties.

It is a further object of the present invention to provide a single material film for recyclable flexible packaging applications.

It is yet another object of the present invention to provide packaging films wherein the non-recyclable thermoplastic material is at least partially replaced by nanocrystalline cellulose without compromising the performance of such films.

It is yet another object of the present invention to use a combination of polyethylene nanocrystalline cellulose composites to obtain films with properties suitable for flexible packaging, preferably for home care and personal care products.

It is yet another object of the present invention to provide a method for uniformly dispersing dried natural nanocrystalline cellulose in a polymer matrix with minimal damage to the nanocellulose and improved mechanical and thermal properties compared to polymers without nanocellulose.

It is yet another object of the present invention to provide a method of producing a film in which nanocrystalline cellulose is produced in situ from agglomerated nanocrystalline cellulose, thereby reducing the risk of using nano-sized particles in production equipment.

Disclosure of Invention

The inventors have surprisingly found that a film comprising nanocrystalline cellulose having a specific aspect ratio provides improved functional properties, such as thermal and mechanical properties, and further that the film is better suited for recycling. It has further preferably been found that films comprising a polyolefin, more preferably polyethylene, in combination with nanocrystalline cellulose having a specific aspect ratio range provide improved functional properties, such as thermal and mechanical properties, which are suitable for the preparation of flexible packaging, preferably for home care and personal care products.

The present invention is directed to providing polymer compositions and films prepared with such polymer compositions, wherein the nanocrystalline cellulose is uniformly dispersed into the polymer matrix with minimal damage and/or agglomeration. The present invention provides a process by which the tendency of nanocrystalline cellulose to form aggregates in a thermoplastic polymer matrix is significantly minimized. The present invention achieves at least some of the above objects by providing a polymer composition having a thermoplastic polymer and nanocrystalline cellulose having a specific aspect ratio in the presence of a compatibilizing agent, and preferably a wetting and dispersing agent (a wetting and dispersing agent). As used herein, "aspect ratio" refers to the ratio between the diameter and the length of the nanocrystalline cellulose. The higher the aspect ratio, the shorter the nanocrystalline cellulose relative to the diameter. For the purposes of the present invention, the aspect ratio ranges from 1:1 to 1: 4.

"film" means a sheet-like structure having a length, a width and a thickness (caliper), wherein the length and the width each greatly exceed the thickness, i.e., 1,000 times or more, said structure having one layer (monolayer) or a plurality of respectively adjacent layers (multilayer), each layer being a continuous structure formed from a single type of thermoplastic polymer resin, including blends thereof.

Detailed Description

According to a first aspect of the invention, a polymer composition is disclosed having a thermoplastic polymer, nanocrystalline cellulose, a compatibilizer, and preferably a wetting dispersant.

Thermoplastic polymers

The polymer composition of the present invention comprises a thermoplastic polymer.

The thermoplastic polymer may be any one of the plastics selected from the group consisting of: polyesters, polyolefins, polyamides, Polystyrenes (PS), polyanhydrides, polyacrylates, polyhydroxyalkanoates, thermoplastic elastomers, thermoplastic polyurethanes, Polycarbonates (PC), polylactic acids (PLA), acrylonitrile/butadiene/styrene copolymers (ABS), styrene/acrylonitrile copolymers (SAN), Polyoxymethylene (POM), biodegradable thermoplastics, starch-based thermoplastics, derivatives and/or mixtures thereof.

Preferably, the thermoplastic polymer is a polyolefin. The term "polyolefin" as used herein includes a class of thermoplastic polymers widely used in the consumer and petrochemical industries and refers to polymers comprising, in polymerized form, a major amount of an olefin monomer, such as ethylene or propylene (based on the weight of the polymer), and optionally may comprise one or more comonomers.

Polyolefins are generally prepared from simple olefins (also known as olefins having the formula C)_nH_2nOlefin(s) as a monomer. For example, Polyethylene (PE) is prepared by reacting the olefin ethylene (C)₂H₄) Polyolefins produced by polymerization. The polypropylene (PP) is made of olefin propylene (C)₃H₆) Another common polyolefin is prepared. Copolymers of ethylene and propylene are also thermoplastic polymers useful according to the present disclosure.

In some embodiments of the invention, the polyolefin may also include elastomeric polymers such as homopolymers of conjugated dienes (especially butadiene or isoprene), and random or block copolymers and terpolymers of at least one conjugated diene (especially butadiene or isoprene) with at least one aromatic u-olefin (especially styrene and 4-methylstyrene), aromatic diene (especially divinylbenzene). In other embodiments of the invention, the polyolefin may include natural or synthetic Polyisoprene (PI) and Polybutadiene (PB).

Other non-limiting examples of polyolefins include, but are not limited to, ethylene-based polymers such as High Density Polyethylene (HDPE), Low Density Polyethylene (LDPE), Linear Low Density Polyethylene (LLDPE), homogeneously branched linear ethylene/polyolefin interpolymers, or homogeneously branched substantially linear ethylene/α -olefin interpolymers; propylene-based polymers such as propylene homopolymers and propylene interpolymers, which may be random or block copolymers, branched polypropylenes, or propylene-based terpolymers; blends of two or more polyolefins, such as blends of ethylene-based polymers and propylene-based polymers discussed above; halogenated ethylene-based polymers, such as chlorinated ethylene-based polymers and fluorinated ethylene-based polymers.

One preferred polyolefin according to the present invention is polyethylene. "polyethylene" or "ethylene-based polymer" refers to a polymer comprising greater than 50 weight percent of units derived from ethylene monomer. This includes polyethylene homopolymers or copolymers (referring to units derived from two or more comonomers), common forms of polyethylene known in the art including Low Density Polyethylene (LDPE); linear Low Density Polyethylene (LLDPE); ultra Low Density Polyethylene (ULDPE); very Low Density Polyethylene (VLDPE); single-site catalyzed linear low density polyethylenes, including linear and substantially linear low density resins (m-LLDPE); medium Density Polyethylene (MDPE); and High Density Polyethylene (HDPE).

"LDPE" may also be referred to as "high pressure ethylene polymer" or "highly branched polyethylene" and is partially or fully homopolymeric or copolymeric. LDPE resins typically have a viscosity in the range of 0.916 to 0.935g/cm³Density within the range. The term "LLDPE" includes resins prepared using conventional Ziegler-Natta catalyst systems as well as single site catalysts, including but not limited to dual metallocene catalysts (sometimes referred to as "m-LLDPE") and constrained geometry catalysts, and including linear, substantially linear, or heterogeneous polyethylene copolymers or homopolymers. LLDPE contains less long chain branching than LDPE and includes substantially linear ethylene polymers, which are further described in U.S. patent 5,272,236, U.S. patent 5,278,272, U.S. patent 5,582,923 and U.S. Pat. No. 5,733,155; homogeneously branched linear ethylene polymer compositions such as those in U.S. Pat. No. 3,645,992; heterogeneously branched ethylene polymers such as those prepared according to the process disclosed in U.S. Pat. No. 4,076,698; and/or blends thereof (such as those disclosed in US3,914,342 or US5,854,045). LLDPE can be produced via gas phase, solution phase or slurry polymerization, or any combination thereof, using any type of reactor or reactor configuration known in the art. "MDPE" means a density of from 0.926 to 0.935g/cm³The polyethylene of (1). "MDPE" is typically prepared using chromium or Ziegler-Natta catalysts or using single site catalysts, including but not limited to dual metallocene catalysts and constrained geometry catalysts, and typically has a molecular weight distribution ("MWD") of greater than 2.5. The term "HDPE" refers to a density greater than about 0.935g/cm³Typically prepared with a Ziegler-Natta catalyst, a chromium catalyst, or a single site catalyst including, but not limited to, a dual metallocene catalyst and a constrained geometry catalyst. The term "ULDPE" refers to a density of 0.880 to 0.912g/cm³Typically prepared with a Ziegler-Natta catalyst, a chromium catalyst, or a single site catalyst (including but not limited to dual metallocene catalysts and constrained geometry catalysts).

A wide variety of polyethylenes can be used depending on a number of factors including, for example, the desired properties of the polymer composition, the desired properties of the film and/or article made from the polymer blend, and the desired properties of the article made from such film. It may be preferred to use a blend of two or more different polyethylenes.

Preferably, the polyethylene has a density in the range of 0.870g/cm³To 0.970g/cm³More preferably, the density is in the range of 0.920g/cm³To 0.955g/cm³. Preferably, the density is at least 0.900g/cm³More preferably at least 0.910g/cm³And still more preferably at least 0.915g/cm³Most preferably at least 0.920g/cm³But usually not more than 0.970g/cm³And still more preferably not more than 0.960g/cm³And still more preferably not more than 0.960g/cm³And most preferably not more than 0.955g/cm³. Preferably, the polyethylene has a melt index (I) of 50g/10 min or less₂) Preferably 20g/10 min or less, wherein the melt index is measured at 190 ℃ and 2.16Kg standard weight. All individual values and subranges up to 20g/10 minutes are included herein and disclosed herein. For example, the polyethylene may have a melt index from a lower limit of 0.2, 0.25, 0.5, 0.75, 1, 2, 4, 5, 10, or 15g/10 minutes to an upper limit of 1, 2, 4, 5, 10, or 15g/10 minutes. In some embodiments, the polyethylene has a melt index (I) of at most 15g/10 minutes₂). In some embodiments, the polyethylene has a melt index (I) of at most 10g/10 minutes₂). In some embodiments, the polyethylene has a melt index (I) of less than 5g/10 minutes₂)。

Polyethylenes particularly suitable for use in the present invention include Linear Low Density Polyethylene (LLDPE), Low Density Polyethylene (LDPE), High Density Polyethylene (HDPE), Enhanced Polyethylene (EPE), and combinations thereof. Various commercially available polyethylenes are contemplated for use in the polymer compositions of the present invention. Examples of commercially available LDPE that can be used according to the present invention include LDPE available under the name DOW LDPE from the Dow Chemical Company^TMAnd AGILITY^TMThose obtained. Examples of commercially available LLDPE's that can be used in accordance with the present invention include DOWLEX, available from the Dow Chemical Company^TMLinear low density polyethylene, e.g. DOWLEX^TM2038.68G. Examples of commercially available HDPE that may be used in embodiments of the present invention include those available under the name DOW from the Dow Chemical Company^TMHDPE resins and DOWLEX^TMThose obtained. In addition to the HDPE resin, the polyolefin used in the polymer composition may also include an enhanced polyethylene. Examples of commercially available enhanced polyethylene resins that may be used in accordance with the present invention include ELITE^TM、ELITE^TMAT and AFFINITY^TMReinforcing polyethylenes, e.g. ELITE^TM5400G, which is commercially available from the Dow Chemical Company. An example of another polyethylene resin that may be used in accordance with the present invention is INNATE available from the Dow Chemical Company^TMA polyethylene resin. Based on the teachings herein, any other suitable commercially available polyethylene may be selected for the polymer combinationA compound (I) is provided.

Preferably, the thermoplastic polymer is a blend of two or more polymers. The polymer blend preferably comprises a combination of two or more of LDPE, LLDPE, metallocene LLDPE and HDPE. Preferred combinations of thermoplastic polymers include LLDPE and LDPE, metallocene LLDPE and LDPE, HDPE and LDPE. The most preferred combination is metallocene LLDPE and LDPE. Preferably, the LLDPE is a bimodal terpolymer LLDPE.

The polymer composition according to the invention comprises 40 to 99 wt.% of the thermoplastic polymer. Preferably, the polymer composition comprises at least 50 wt% of the thermoplastic polymer, further preferably at least 55 wt% of the thermoplastic polymer, further preferably at least 60 wt%, most preferably at least 65 wt%, but generally not more than 97 wt%, further preferably not more than 95 wt%, further more preferably not more than 90 wt%, and most preferably not more than 85 wt%, based on the weight of the polymer composition. Preferably, the polyolefin is polyethylene.

Nanocrystalline cellulose

The polymer composition of the present invention comprises nanocrystalline cellulose having an aspect ratio of 1:1 to 1: 4.

Preferably, the nanocrystalline cellulose has an aspect ratio of at least 1:1, still preferably at least 1:1.1, and further preferably at least 1:1.5, but generally not more than 1:4, still preferably not more than 1:3, and most preferably not more than 1: 2.

Preferably, the polymer composition comprises from 0.01 to 30 wt%, more preferably from 0.01 to 20 wt%, still more preferably from 0.01 to 10 wt% of nanocrystalline cellulose. More preferably, the polymer composition comprises 0.5 to 5 wt% of nanocrystalline cellulose by weight of dry matter, based on the total weight of the polymer composition. Preferably, the amount of nanocrystalline cellulose in the polymer composition is at least 0.5 wt%, still preferably at least 1 wt%, further preferably at least 1.5 wt%, still more preferably 2 wt%, and most preferably at least 3 wt%, but generally not more than 10 wt%, still preferably not more than 8 wt%, still more preferably not more than 6 wt%, and most preferably not more than 5 wt%. In yet another embodiment of the polymer composition, the amount of nanocrystalline cellulose in the composition is preferably at least 10 wt.%, still preferably at least 11 wt.%, further preferably at least 12 wt.%, still more preferably at least 14 wt.%, and most preferably at least 15 wt.% of the composition, but generally not more than 25 wt.%, still preferably not more than 22 wt.%, still more preferably not more than 21 wt.%, and most preferably not more than 20 wt.% of the composition.

Nanocrystalline cellulose is commercially available as a liquid composition having a solids content of 5 wt.%, more preferably having a solids content of 12 wt.%. The nanocrystalline cellulose may be in the form of a suspension or a solid. The powder form may be prepared by spray drying or freeze drying processes. Preferably, when the nanocrystalline cellulose is in solid form, it is preferably in powder form. Preferably, the nanocrystalline cellulose in solid form has at least 0.7g/cm³The density of (c). Preferably, the nanocrystalline cellulose XRD has a crystallinity index of at least 75%, preferably 87%, still preferably at least 90%, further preferably at least 95%, still further preferably at least 98%, and most preferably 99%.

Nanocrystalline cellulose is preferably prepared by dissolving pulp, cotton, bleached kraft pulp (softwood pulp, hardwood pulp) using acid hydrolysis. The nanocrystalline cellulose is preferably modified by chemical modification by various methods known to those skilled in the art of preparing nanocrystalline cellulose, including but not limited to TEMPO-mediated oxidation, cationization, carboxylation, and polymer grafting.

The nanocrystalline cellulose is preferably a linear long chain glucose polymer rich in oxygen, particularly hydroxyl groups. These hydroxyl groups form hydrogen bonds, which give the nanocrystalline cellulose its intrinsic strength, while providing a reactive surface for the hydroxyl groups on two of the crystal faces. Although not all hydroxyl groups are equally reactive and accessible, they are sufficient to allow multiple reactions. Hydroxyl groups are also responsible for the inherent hydrophilicity of nanocrystalline cellulose. The nanocrystalline cellulose is preferably surface modified, and is also preferably treated with sulfur.

Preferably, the nanocrystalline cellulose also comprises acidic groups attached to its surface, which allow for reaction with various bases. While many traditional products (such as cellulose acetate, carboxymethyl cellulose, and cellulose ethers) take advantage of the reactivity of cellulose, nanocrystalline cellulose allows for the incorporation of a variety of hydrophobic structures. This makes the material compatible with a large amount of solvent and polymer matrix. Nanocrystalline cellulose may be hydrophobic or hydrophilic.

One gram of nanocrystalline cellulose preferably comprises more than 125 trillion (10)¹⁶) Particles, each preferably having 4500nm²Theoretically providing about 550m of surface area²Per g surface area of nanocrystalline cellulose material. The surface area is affected by the mass of the dispersion of particles in the medium and whether the nanocrystalline cellulose material has dried or redispersed back into the medium.

Preferably, the nanocrystalline cellulose is a charged nanocrystalline cellulose material, and the functional group imparts a negative charge to the crystal surface.

Preferably, the nanocrystalline cellulose is from Celluforce as Celluforce NCC^TMAre commercially available.

The number average particle size of the nanocrystalline cellulose present in the polymer composition is preferably in the range of 25 to 600nm, more preferably 25 to 170 nm. Most preferably, the nanocrystalline cellulose is substantially spherical.

Preferably, the number average particle size of the nanocrystalline cellulose in the polymer composition is at least 25nm, still preferably at least 50nm, further preferably at least 60nm, still further preferably at least 100nm, and most preferably at least 125nm, but generally not more than 600nm, preferably not more than 550nm, still preferably not more than 450nm, still more preferably not more than 400nm, and most preferably not more than 350 nm.

The nanocrystalline cellulose may preferably be combined with the thermoplastic polymer prior to forming the melt phase. In a preferred embodiment, the nanocrystalline cellulose may be combined with the thermoplastic polymer in the form of a blend, master batch, compound, pellet, or powder. Nanocrystalline cellulose may also be combined with a thermoplastic polymer while forming a melt phase. The nanocrystalline cellulose may be introduced into the melt phase in the form of a blend, masterbatch, compound, pellet, or powder comprising both the hydrophilic cellulose and the thermoplastic polymer.

Compatilizer

The polymer composition according to the invention comprises a compatibilizer.

Preferably, the compatibilizer is selected from the group consisting of Ethylene Vinyl Acetate (EVA), Ethylene Acrylic Acid (EAA), styrene butadiene styrene block copolymer (SBS), copolymers of polyethylene and maleic anhydride, and combinations thereof.

Compatibilization in polymer chemistry is the addition of substances to immiscible blends of two or more polymers to increase their stability. Generally, and without wishing to be bound by theory, the function of the compatibilizing agent used in the present invention is to reduce the interfacial tension (i.e., enhance the interface between the phases) and thus improve the mechanical properties of the stabilized blend (e.g., reduce the size and morphology of the phase separated phases). The compatibilizing agent is believed to strengthen the interface by extending the interface from a sharp change in composition and properties to a wider gradual transition interface. Polymer blends often include unstable phase morphology, resulting in poor mechanical properties. Compatibilizing the system will result in a more stable and better miscible phase morphology by creating interactions between two or more otherwise immiscible (or partially miscible) polymers.

The polymer composition according to the present invention comprises a compatibilizer, which is preferably a maleated polymer selected from the group consisting of maleated polyethylene, maleated polypropylene, maleated polystyrene, maleated polylactide, maleated poly (ethylene terephthalate), and combinations thereof. Preferably, the maleated polymer is biomass-based, biodegradable, and/or compostable. In some embodiments, the maleated polymer is biomass-based, biodegradable, and/or compostable. Preferably, the thermoplastic polymer and maleated polymer may be formed from common polymers, which are preferably biomass-based, biodegradable, and/or compostable. The maleated polymer may be derived from, for example, maleic anhydride produced from biomass-derived 5-hydroxymethylfurfural.

Preferably, the compatibilizer is maleic anhydride grafted polyethylene (MAH-g-PE). It is believed that MAH-g-PE further enhances the compatibility of nanocrystalline cellulose within the polyethylene matrix. The grafted polyethylene can be any number of grafted polyethylenes, including, for example, Ultra Low Density Polyethylene (ULDPE), Low Density Polyethylene (LDPE), Linear Low Density Polyethylene (LLDPE), Medium Density Polyethylene (MDPE), High Density Polyethylene (HDPE), high melt strength high density polyethylene (HMS-HDPE), Ultra High Density Polyethylene (UHDPE), and combinations thereof. In some embodiments, the grafted polyethylene comprises linear low density polyethylene, or high density polyethylene.

The compatibilizing agent is present in the polymer composition at a concentration of from 0.1 to 10 weight percent, more preferably from 0.1 to 5 weight percent, based on the weight of the composition. Preferably, the amount of compatibilizer in the polymer composition is at least 0.1 weight percent, still preferably at least 0.5 weight percent, further preferably at least 0.8 weight percent, and most preferably at least 1 weight percent, but generally not more than 5 weight percent, still preferably not more than 4.5 weight percent, and most preferably not more than 3 weight percent. Most preferably, the polymer composition comprises 1 to 3 wt% of the compatibiliser, based on the weight of dry matter.

Preferred polymer compositions comprise 40 to 99 wt% of the thermoplastic polymer, 0.01 to 30 wt% of the nanocrystalline cellulose and 0.1 to 10 wt% of the compatibilizer. In the preparation of films from such polymer compositions, the polymer composition is further blended with a thermoplastic polymer prior to forming the film. Without wishing to be bound by theory, it is believed that the process of blending the polymer composition with the thermoplastic polymer prior to forming the film avoids degradation of the composition and improves the thermal stability of the film produced.

Wetting and dispersing agent

The polymer composition of the present invention preferably comprises a wetting dispersant.

The wetting dispersant is present in the polymer composition at a concentration of 0.5 wt.% to 30 wt.%, based on the weight of the composition. Preferably, the amount of wetting dispersant in the polymer composition is at least 0.5 wt.%, still preferably at least 1 wt.%, further preferably at least 1.5 wt.%, most preferably at least 2 wt.%, but generally not more than 30 wt.%, still preferably not more than 20 wt.%, and most preferably not more than 10 wt.%. Preferably, the polymer composition comprises from 0.5 to 10 wt%, more preferably from 0.5 wt% to 5 wt% of wetting dispersant, based on the weight of dry matter.

Preferably, the wetting dispersant is a blend of different fatty acid esters having a melting range and includes a low melting portion and a high melting portion. Without wishing to be bound by theory, it is believed that the low melting fraction provides rapid wetting and low melt viscosity and reduces the compaction of the nanocrystalline cellulose in the first part of the extrusion process. The wetting dispersant adsorbs onto the nanocrystal surface, which results in a more uniform dispersion. The high melting point portion reduces the melt viscosity of the masterbatch or compound during extrusion. This results in improved processing.

Preferably, the wetting dispersant is commercially available and is a fatty acid ester copolymer having acidic groups and having 65% actives adsorbed onto silica, commercially available as BYK-P4101 from BYK Chemie.

Other components:

the polymer composition according to the present invention may comprise at least one of an oxidizing agent, a colorant, a slip agent (slip agent), a pigment, an antioxidant, an antiblock agent, a processing aid, or a combination thereof, which may be incorporated into the polymer composition by blending prior to an appropriate stage of the process.

Process for preparing a polymer composition

According to a second aspect of the present invention there is provided a process for preparing the polymer composition of the first aspect, the process comprising the steps of:

i. providing a thermoplastic polymer;

providing a substrate having a thickness of 4 to 40 microns; more preferably 14 to 16 microns in spherical diameter solid agglomerated form of nanocrystalline cellulose;

providing a compatibilizing agent;

at a temperature in the range of from 130 ℃ to 210 ℃ in a range of from 785 to 12560s^-1Combining the thermoplastic polymer, the nanocrystalline cellulose in solid agglomerated form, the compatibilizer, preferably by a screw having a compression ratio of 1.5 to 1.8 and a screw rotation of preferably 40 to 60 rpm;

v. providing a polymer composition, wherein the nanocrystalline cellulose is modified in situ to provide a thermoplastic polymer matrix of nanocrystalline cellulose having an aspect ratio of 1:1 to 1: 4.

In the first step of preparing the polymer composition according to the invention, the nanocrystalline cellulose in agglomerated form is combined with a thermoplastic polymer or polymer combination prior to or simultaneously with the formation of the melt phase. For example, the nanocrystalline cellulose in agglomerated form may be combined with a polymer or combination of polymers in the form of a blend, masterbatch, pellet, compound, or powder. Alternatively, the nanocrystalline cellulose in agglomerated form may be introduced into the melt phase in the form of a blend, masterbatch, pellet, compound, or powder containing the nanocrystalline cellulose in agglomerated form and a polymer or combination of polymers.

Preferably, the polymer composition according to the present invention may be prepared by melt blending the components according to the first aspect in specified amounts with a twin screw extruder before feeding to the extruder or other equipment for film manufacture. Such a polymer composition may also be prepared by drum blending the specified amounts of the components according to the first aspect before feeding to an extruder or other equipment for film manufacture. In some embodiments, the polymer composition of the present invention may be in the form of pellets. For example, the components may be melt blended and then formed into pellets using a twin screw extruder or other techniques known to those skilled in the art based on the teachings herein.

Films prepared from polymer compositions

According to a third aspect of the present invention, there is disclosed a film comprising the polymer composition of the first aspect or prepared according to the method of the second aspect. The film may be prepared by any method generally known in the art including, but not limited to, compression molding, injection molding, blown film extrusion, and more preferably the film is prepared by blow molding.

Preferably, the compression moulded film comprises a thermoplastic polymer, nanocrystalline cellulose, a compatibilizer, wherein the nanocrystalline cellulose has an aspect ratio of 1:1 to 1:4 and preferably has a number average particle size of 395nm to 505 nm.

Preferably, the injection molded component comprises a thermoplastic polymer, nanocrystalline cellulose, a compatibilizer, wherein the nanocrystalline cellulose has an aspect ratio of 1:1 to 1:4, and preferably has a number average particle size of 125nm to 150 nm.

Preferably, the extrusion blown film comprises a thermoplastic polymer, nanocrystalline cellulose, a compatibilizer, wherein the nanocrystalline cellulose has an aspect ratio of 1:1 to 1:4, and preferably has a number average particle size of 65nm to 150 nm.

Preferably, the extruded casting film comprises a thermoplastic polymer, nanocrystalline cellulose, a compatibilizer, wherein the nanocrystalline cellulose has an aspect ratio of 1:1 to 1:4, and preferably has a number average particle size of 65nm to 150 nm. Extrusion blown or cast films may preferably be oriented in the machine direction, the transverse direction, or both.

Preferably, the film according to the invention is a monolayer film or a multilayer film. Such monolayer and multilayer films can generally be prepared using techniques known to those skilled in the art based on the teachings herein. The multiple layers of the film may include tie/sealant layers between the layers, or laminated to each other or otherwise bonded together with different film structures. Preferably, the film is a blown film or a cast film.

Preferably, the ratio of the weight percent of nanocrystalline cellulose to the weight percent of the compatibilizing agent in the film is between 1:3 and 1: 5.

Preferably, the membrane according to the invention has a thickness of 10 to 300 microns, more preferably 10 to 100 microns, still preferably 10 to 75 microns, preferably 30 to 50 microns.

Preferably, in some embodiments, the film according to the invention is printed, preferably reverse printed.

Preferably, a method for preparing a membrane according to any one of the preceding aspects, the method comprising the steps of:

i. providing a thermoplastic polymer, preferably in an amount of 40 to 99 wt.%;

providing a substrate having a thickness of 4 to 40 microns; more preferably 14 to 16 microns in spherical diameter, preferably in an amount of 0.01 to 30 wt%;

providing a compatibilizing agent, preferably in an amount of 0.1 to 10 weight percent;

785 to 12560s at a temperature of 130 ℃ to 210 ℃^-1Combining the thermoplastic polymer, nanocrystalline cellulose, compatibilizer, preferably produced by a screw having a compression ratio of 1.5 to 1.8 and a screw rotation of preferably 40 to 60 nm;

v. providing a polymer composition, wherein the crystalline cellulose is modified in situ to provide a thermoplastic polymer matrix of nanocrystalline cellulose having an aspect ratio of 1:1 to 1: 4; .

Combining the polymer composition prepared from step (v) with a thermoplastic polymer; and the combination of (a) and (b),

forming a film.

According to another aspect of the invention, a package formed from the film according to the third aspect of the invention is disclosed. Examples of such packaging may include flexible packaging, pouches, stand-up pouches, and prefabricated packaging or pouches. Such packages may be formed using techniques known to those skilled in the art in view of the teachings herein.

Some embodiments of the present invention will now be described in detail in the following examples.

Examples

Example 1: polymer compositions having nanocrystalline cellulose in a polymer matrix were evaluated.

The polyethylene polymer, nanocrystalline cellulose, compatibilizer, and wetting agent were provided in the specific amounts as provided in table 1 and mixed (melt compounded) in a screw extruder to prepare the polymer composition.

TABLE 1

The polymer composition was then injection molded to produce injection molded articles and various parameters were tested, the resulting data being given in table 2.

The measurement technology comprises the following steps:

SEM analysis:crystal morphology and structure can be determined by standard techniques known to those skilled in the art, such as Scanning Electron Microscopy (SEM). SEM is an imaging and analysis technique based on the detection of electrons and X-rays emitted from a material when irradiated by a scanning electron beam. Imaging allows the user to distinguish between primary particle and agglomerate sizes.

Automated image analysis using computer software enables a user to determine the particle size distribution. Scanning Electron Microscopy (SEM) is a particle counting technique and produces a number weighted size distribution. Thus, the numbers quoted herein for particle length and width generally refer to the average value for the population of particles, and more specifically the D [1,0] number-length average value for the particle length or particle width, respectively.

Thermogravimetric analysis:thermogravimetric analysis (TGA) is a thermal analysis method in which changes in the physical and chemical properties of a material are measured as a function of elevated temperature or as a function of time. Thermogravimetric analysis (TGA) was measured in a Perkin Elmer Pyris1 TGA instrument.

A rheometer:rheology is defined as studying the flow and deformation of a material, which describes the interrelationship between force, deformation and time. The most common flow behavior and most easily measured on a rotational rheometer or viscometer is shear flow. The rheology of the polymer composition was measured by MCR101, Anton Paar, UK.

DSC analysis:differential scanning volumeThermal methods ("DSCs") are a thermal analysis technique that measures temperature and heat flow associated with the transformation of a material as a function of time and temperature. These measurements provide quantitative and qualitative information about the sample transitions involving endothermic or exothermic processes, or changes in heat capacity. Crystallinity has a large influence on the hardness, density, transparency, softening point and diffusion of solid materials. Many polymers have both crystalline and amorphous regions. In these cases, the crystallinity is specified as a percentage of the mass of the material as crystals with respect to the total mass. Crystallinity can be measured using X-ray diffraction techniques and Differential Scanning Calorimetry (DSC). DSC measurements were performed in a differential scanning calorimeter-Waters Q100 instrument and the data recorded and provided in table 2.

TABLE 2

The data presented in table 2 show that the film 1 according to the invention has improved mechanical and thermal properties compared to film a. The film 1 according to the invention has a higher enthalpy, which indicates that it can absorb a higher thermal energy before deformation when compared to the comparative film a, allowing a wider heat sealing window.