KR102224439B1 - Composition for barrier film coating, barrier film comprising the same and preparation method thereof - Google Patents

Abstract

In the present specification, as a composition for coating a barrier film, the composition for coating a barrier film includes cellulose nanofibers; Water-soluble binders; Nano clay; Crosslinking agent; And a solvent, wherein the cellulose nanofibers, the water-soluble binder, and the nanoclay are crosslinked with each other, and a composition for coating a barrier film is disclosed.

Description

A composition for coating a barrier film, a barrier film including the same, and a method for manufacturing the same {COMPOSITION FOR BARRIER FILM COATING, BARRIER FILM COMPRISING THE SAME AND PREPARATION METHOD THEREOF}

The present invention relates to a composition for coating a barrier film having improved gas barrier and moisture barrier properties, a barrier film including the same, and a method of manufacturing the same.

[Explanation of nationally supported R&D]

This research was conducted under the supervision of Yulchon Chemical Co., Ltd. with the support of the Institute for Industrial Technology Evaluation. The name of the research project is an industrial core technology development project, and the title of the research project is high barrier cellulose nanoparticles with an oxygen permeability of 0.5/water permeability of 1.0 or less for food and pharmaceutical packaging materials. It is the development of a fiber-based eco-friendly transparent composite film (task number: 10067368).

Cellulose nanofibers (nano fibers) are natural fibers or synthetic fibers with a diameter of about 1 to 100 nm, and are generally expected to be developed for various uses such as reinforcing materials for composite materials.

In other words, because it is a natural-derived fiber extracted from plant biomass, it can contribute to the realization of a low-carbon society, and by breaking down to the nano level, various properties not found in conventional paper or pulp are expressed, and a resin composite material for the purpose of improving strength and reducing weight, It is expected to be used as various functional additives such as films and sheets utilizing transparency barrier properties, porous sheets utilizing nano-sized process control, thickeners and dispersants.

On the other hand, packaging materials used for packaging of foods, non-foods, pharmaceuticals, and the like are required to have gas/water barrier properties in order to suppress deterioration of the contents and maintain their functions and properties. Conventionally, for such a packaging material, a packaging material in which a metal foil made of a metal such as aluminum or a vinylidene chloride film is used as a gas barrier layer having little influence due to temperature and humidity has been generally used.

Cellulose nanofiber coating films are currently actively researching films and sheets utilizing transparency and gas barrier properties, but practical standards such as required performance and quality of coating films have not been established.

In particular, studies on moisture barrier properties are insufficient due to the properties of cellulose nanofibers bonded by hydrogen bonds, but in addition to oxygen barrier properties as packaging materials for foods and pharmaceuticals, the demand for moisture barrier properties is increasing.

KR 10-2013-0096755 A JP 6228118 B KR 10-2013-0018248 A

It is an object of the present invention to provide a composition for coating a barrier film having improved gas barrier properties as well as moisture barrier properties, a barrier film including the same, and a method of manufacturing the same, as compared with a conventional barrier film.

In exemplary embodiments of the present invention, as a composition for coating a barrier film, the composition for coating a barrier film is a cellulose nanofiber; Water-soluble binders; Nano clay; Crosslinking agent; And containing a solvent, the cellulose nanofibers; Water-soluble binders; And nano-clay; is cross-linked with each other provides a barrier film coating composition.

In still other exemplary embodiments of the present invention, a base film; And a barrier layer provided on the base film and including the composition for coating the barrier film described above.

In still other exemplary embodiments of the present invention, a method for preparing a composition for coating a barrier film described above, comprising: preparing cellulose nanofibers using pulp; Adding a water-soluble binder and nano clay to the aqueous solution containing the cellulose nanofibers; And adding a crosslinking agent to the aqueous solution.

In still other exemplary embodiments of the present invention, preparing a base film; And forming a barrier layer by applying the composition for coating the barrier film on the base film.

According to exemplary embodiments of the present invention, the composition for coating a barrier film of the present invention may include a water-soluble binder and nano clay in cellulose nanofibers, and thus a barrier film having excellent gas barrier and moisture barrier can be prepared.

1A to 1C show photographs of cellulose nanofibers according to concentrations according to an embodiment of the present invention.
2 shows a SEM photograph of a surface of a barrier film coated with a composition for coating a barrier film according to an embodiment of the present invention.
3 is a schematic diagram showing a method of preparing a composition for coating a barrier film according to an embodiment of the present invention.

In the present specification, when a certain part "includes" a certain component, it means that other components may be further included rather than excluding other components unless specifically stated to the contrary.

In the present specification, the degree of saponification of polyvinyl alcohol refers to the degree to which the acetate group in the polyvinyl alcohol molecule is substituted with a hydroxy group. Accordingly, the high degree of saponification of polyvinyl alcohol means that the polyvinyl alcohol has hydrophilicity, and in proportion to this, it means that it exhibits excellent barrier properties, that is, high gas barrier properties, against gases such as oxygen having non-polarity.

Specifically, it can be measured by the method described in JIS, and can be expressed as a ratio of the number of moles of the compound converted to -OH group to the number of moles of the compound having _{all -OCOCH 3 groups.}

Hereinafter, exemplary embodiments of the present invention will be described in detail.

In exemplary embodiments of the present invention, as a composition for coating a barrier film, the composition for coating a barrier film is a cellulose nanofiber; Water-soluble binders; Nano clay; Crosslinking agent; And containing a solvent, the cellulose nanofibers; Water-soluble binders; And nano clay; It provides a composition for coating a barrier film that is cross-linked with each other.

As a general barrier film coating composition, when the natural cellulose concentration is 1 wt% or more, the viscosity increases, it is difficult to form a film by casting, and it is difficult to satisfy the moisture barrier properties in addition to the gas permeability. In addition, even when cellulose nanofibers are blended with a silane coupling agent, there is a problem that it is difficult to form a barrier property of moisture permeability similarly.

In order to solve the above problem, the present inventors have mixed a water-soluble binder and nano-clay in a cellulose nanofiber coating aqueous solution made by a physical fluid collision method without chemical treatment unlike the prior art, and crosslinked with each other by a crosslinking agent to form a dense film, A composition for coating a barrier film that can improve oxygen and moisture barrier properties and has improved adhesion when coating as a barrier layer on a base film has been developed.

In an exemplary embodiment, the diameter of the cellulose nanofibers may be 1 to 100 nm, and the length may be 1 to 200 nm. When the diameter of the cellulose nanofibers is more than 100 nm, the gap between the fibers becomes large, and the gaps are connected in the film to form a through hole, and the structure may be a structure that allows gas such as oxygen or water vapor to easily permeate. When the diameter is less than 1 nm, a path way through which gas and moisture can easily pass may be formed, and the barrier properties may be deteriorated. In addition, when the length is more than 200 nm, the viscosity of the composition increases, and it may be difficult to obtain an even coating surface during coating.

In an exemplary embodiment, the content of the cellulose nanofibers may be 0.3 to 5% by weight, and preferably 1 to 3% by weight, based on the total weight of the composition for coating the barrier film. In the case of the present invention, even when the content is 0.3% by weight or more, the cellulose nanofibers are homogeneously dispersed, so that the moisture barrier property is excellent. When the content is less than 0.3% by weight, it is difficult to form a barrier layer, and when the content is more than 5% by weight, the viscosity increases and it is difficult to obtain an even coating surface.

In an exemplary embodiment, the water-soluble binder is polyvinyl alcohol (PVA), hydroxypropyl methyl cellulose (HPMC, Hydroxy Propyl Methyl Cellulose), 2-hydroxy ethyl cellulose (2-hydroxy ethyl cellulos1e), methyl cellulose (methyl cellulose). ), ethyl cellulose and polyethylene glycol (polyethyleneglycol) may be at least one selected from the group consisting of, preferably polyvinyl alcohol (PVA).

In an exemplary embodiment, the water-soluble binder is polyvinyl alcohol (PVA), and the saponification degree of the polyvinyl alcohol (PVA) may be 80 to 100 mol%.

In an exemplary embodiment, the content of the water-soluble binder may be 0.3 to 5% by weight, preferably 1 to 3% by weight, based on the total weight of the barrier film coating composition. The content of the water-soluble binder may be included in the same amount as the cellulose nanofibers to improve adhesion to the base film.

In an exemplary embodiment, the nanoclay is montmorillonite, laponite, bentonite, hectorite, beidellite, nontronite, macadite, It may be one or more selected from the group consisting of mica and fluorinated mica, preferably montmorillonite.

In an exemplary embodiment, the content of the nanoclay may be 0.05 to 5% by weight based on the total weight of the water-soluble binder. When the nano-clay content is less than 0.05% by weight, the barrier film may have very low gas or moisture barrier properties due to excessive physical voids inside, and when the nano-clay content is more than 5% by weight, the coating layer of the barrier film (Barrier layer) Since durability is significantly lowered, physical defects such as cracks may easily occur in the barrier film.

In an exemplary embodiment, the crosslinking agent may have two or more hydroxy groups. Since the crosslinking agent has two or more hydroxy groups, it is possible to construct a dense membrane by crosslinking cellulose nanofibers, water-soluble binders, and nanoclays. In addition, by including the crosslinking agent, the concentration of the composition can be lowered, so that the coating process can be smoothly performed and a composition having excellent barrier properties can be provided.

In an exemplary embodiment, the crosslinking agent is dialdehyde, glyoxal, glutaraldehyde, polycarboxylic acid, citric acid, succinic acid, tartaric acid. (tartaric acid), ethylmalonic acid (ethylmalonic acid) and adipic acid dihydrazide (adipic acid dihydrazide, ADH) may be at least one selected from the group consisting of, preferably glutaraldehyde (glutaraldehyde) may be. .

In an exemplary embodiment, the content of the crosslinking agent may be 0.05 to 5% by weight based on the total weight of the nanoclay. When the content of the crosslinking agent is less than 0.05% by weight, the cellulose nanofibers, the water-soluble binder, and the nanoclay may not be sufficiently crosslinked with each other, and when the content is more than 5% by weight, the crosslinking density of the composition increases rapidly, resulting in a solution coating. The process can be difficult to proceed.

In an exemplary embodiment, the solvent may be water, more specifically distilled water.

In an exemplary embodiment, the composition for coating the barrier film may be for manufacturing a food or pharmaceutical packaging material.

In exemplary embodiments of the present invention, a base film; And a barrier layer provided on the base film and including the composition for coating the barrier film described above.

In an exemplary embodiment, the base film may include polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polycarbonate (PC), polymethyl methacrylate (PMMA); Poly(methyl methacrylate)), polyimide (PI), oriented polypropylene (OPP), biaxially oriented polypropylene (BOPP), polyethylene 2,6-dicarboxyl naphthalate (PEN; Polyethylene 2,6-dicarboxyl naphthalate), polyethersulfone (PES), polyester or polystyrene (PS; Polystyrene), preferably polyethylene terephthalate (PET; polyethyleneterephthalate) or stretched polypropylene ( OPP; Oriented Polypropylene).

In an exemplary embodiment, the thickness of the base film may be 10 to 200 μm, and the thickness of the barrier layer may be 0.5 to 3.0 μm.

In exemplary embodiments of the present invention, as a method for preparing a composition for coating a barrier film, the method comprising: preparing cellulose nanofibers using pulp; Adding a water-soluble binder and nano clay to the aqueous solution containing the cellulose nanofibers; And adding a crosslinking agent to the aqueous solution.

Referring to FIG. 3, according to the method for preparing a composition for coating a barrier film of the present invention, a water-soluble binder and nano clay are added to the aqueous solution containing the cellulose nanofibers, and a crosslinking agent is added thereto to obtain cellulose nanofibers, water-soluble binder, and nanoparticles. By crosslinking the clays with each other, a dense film can be formed.

The pulp may be derived, for example, from wood, grass (eg sugarcane, bamboo) or pieces of cloth (eg textile waste, cotton, hemp or flax). The fibrous substrate comprising cellulose may be in the form of pulp (ie, a suspension of cellulose fibers in water), which may be prepared by any suitable chemical or mechanical treatment, or a combination thereof. For example, the pulp may be chemical pulp, chemithermomechanical pulp or mechanical pulp, or recycled pulp, or papermill broke, paper mill waste stream, waste from a paper mill, or a combination thereof. It may be, and preferably may be derived from a broad-leaved tree.

In an exemplary embodiment, the cellulose nanofiber may be manufactured using a fluid collision device, and specifically, the collision angle is 180 degrees, the collision direction is three directions, and the nozzle diameter is 0.3 mm, and the collision passes 100 times at a high pressure of 2800 bar. It can be manufactured by. The composition for coating a barrier film of the present invention produces cellulose nanofibers in a physical fluid impulse method using pulp without separate chemical treatment, so that a dense film is formed and the cellulose nanofibers are uniformly dispersed in an aqueous solution, thereby allowing gas or Moisture barrier properties can be improved.

In exemplary embodiments of the present invention, preparing a base film; And forming a barrier layer by applying the composition for coating the barrier film on the base film.

In an exemplary embodiment, the coating of the composition for coating the barrier film may be performed using a coma coating method, and the drying temperature may be 80 to 120° C., and the drying time may be performed for 1 to 10 minutes. have.

Hereinafter, specific embodiments according to exemplary embodiments of the present invention will be described in more detail. However, the present invention is not limited to the following examples, and various types of examples may be implemented within the scope of the appended claims. It will be understood that it is intended to facilitate the practice of the invention to those of skill in the art.

Example

Barrier Film manufacturing

[Example 1-Preparation of a composition for coating a barrier film]

The type of cellulose nanofibers was made of hardwood wood (Tuetsu Pulp), and using a fluid collision device, the collision angle was 180 degrees, the collision direction was 3 directions, and the nozzle diameter was 0.5 mm, and 100 passes at a high pressure of 2800 bar. One aqueous solution was used. Concentrations of aqueous cellulose nanofibers were prepared in 1.0wt%, 2.0wt%, and 3.0wt%.

Referring to FIGS. 1A-1C, the appearance of cellulose nanofibers by concentration can be confirmed. As the concentration increases, the intermolecular spacing of the cellulose nanofibers becomes narrower, and the entangled form like a thread increases. Therefore, it was confirmed that when the cellulose nanofibers were excessively included, the viscosity increased exponentially, making it difficult to perform a smooth coating process.

Polyvinyl alcohol was added to the cellulose nanofiber aqueous solution equally to the weight of the cellulose nanofibers to prepare a mixed aqueous solution, and after mixing 1 wt% of nanoclay (montmorillonite) compared to polyvinyl alcohol, an ultrasonic disperser for 3 hours The coating solution was reconstituted using.

Thereafter, at this time, a crosslinking agent (glutaraldehyde) having a composition of 2-hydroxy (acid) was added in an amount of 1 wt% compared to the nano clay to induce a crosslinking reaction between cellulose nanofibers + water-soluble binder + nanoclay (see FIG. 3).

[Example 2-Barrier Film Preparation]

In addition, PET50 (SKC) and OPP30 (Yulchon Chemical) were used as the coating base film.

Each coating solution prepared in various formulations in Example 1 was coated on each base film using a comma coater, and then dried at a drying temperature of 100° C. for 2 minutes to prepare a barrier film, and the thickness of the barrier layer after coating was 2 μm. Was measured.

Referring to FIG. 2 showing the SEM image of the surface of the barrier film, it can be seen that the water-soluble binder and the nano clays are closely entangled with each other in the cellulose nanofiber main chain like a thread.

Experimental example

Barrier Film performance evaluation

[Experimental Example]

In order to check the oxygen barrier properties of the barrier film prepared in the above example, the oxygen permeability was measured according to ASTM D3985, and the gas barrier properties were evaluated at 23°C/ 0%RH condition for 3 days using the OXTRAN equipment of MOCON. I did. In addition, the moisture permeability was measured according to ASTM D1249 in order to confirm the moisture barrier property, and the moisture permeability was evaluated for 3 days at 38°C/100% RH using Aquatran equipment of MOCON.

Barrier characteristics result of CNF (cellulose nanofiber)/PVA (polyvinyl alcohol)/nanoclay film forming film on PET50um base film Item In the composition
CNF/ PVA content (wt%) Oxygen permeability (cc/m ² .day) Moisture permeability
(g/m ² .day) PET 50um (uncoated) - 35 14.5 CNF/PVA 1 of 1 4 14.2 2 of 2 3.2 14.2 3 of 3 1.1 14.3 CNF/PVA/Nano Clay
(Does not include crosslinking agent)
-Nano Clay: Contains 1 wt% of PVA 1 of 1 1.0 9.8 2 of 2 0.8 9.2 3 of 3 0.5 9.1 CNF / PVA / Nano Clay / Crosslinking agent
-Nano Clay: Contains 1 wt% of PVA
-Crosslinking agent: contains 1wt% of nano clay 1 of 1 0.5 4.9 2 of 2 0.4 4.4 3 of 3 0.2 4.0

Barrier characteristics result of CNF (cellulose nanofiber)/PVA (polyvinyl alcohol)/nanoclay film forming film on OPP30um base film Item In the composition
CNF/ PVA content (wt%) Oxygen permeability (cc/m ² .day) Moisture permeability
(g/m ² .day) OPP 30um (uncoated) - 1500 6.5 CNF/PVA 1 of 1 384 6.4 2 of 2 365 6.2 3 of 3 291 6.1 CNF/PVA/Nano Clay
(Does not include crosslinking agent)
-Nano Clay: Contains 1 wt% of PVA 1 of 1 56 5.8 2 of 2 51 5.8 3 of 3 48 5.5 CNF / PVA / Nano Clay / Crosslinking agent
-Nano Clay: Contains 1 wt% of PVA
-Crosslinking agent: contains 1wt% of nano clay 1 of 1 5.1 4.0 2 of 2 4.8 3.8 3 of 3 4.3 3.5

Referring to Tables 1 and 2, in the case of coating the composition of the present invention on PET50/OPP30, which is a base film, it was found that when the maximum base film was PET50, the oxygen permeability was improved to 4.0g when 0.2cc OPP30, and moisture permeability. It was found that when the maximum base film was PET50, it was improved to 3.5g when 4.3cc OPP30.

In particular, it was found that when the concentration of cellulose nanofibers and polyvinyl alcohol of the coating composition was contained at a higher concentration than before, it had a more compact structure and thus barrier properties were improved.

Claims (18)

As a composition for coating a barrier film,
The barrier film coating composition includes cellulose nanofibers; Water-soluble binders; Nano clay; Crosslinking agent; And a solvent,
The cellulose nanofibers; Water-soluble binders; And nano clay; are crosslinked with each other,
The content of the cellulose nanofibers is 0.3 to 5% by weight based on the total weight of the composition for coating the barrier film,
The content of the water-soluble binder is 0.3 to 5% by weight based on the total weight of the composition for coating the barrier film,
The content of the nanoclay is 0.05 to 5% by weight based on the total weight of the water-soluble binder,
The content of the crosslinking agent is 0.05 to 5% by weight based on the total weight of the nano-clay, a composition for coating a barrier film. The method of claim 1,
The diameter of the cellulose nanofibers is 1 to 100 nm, characterized in that the length is 1 to 200 nm, barrier film coating composition. delete The method of claim 1,
The water-soluble binder is polyvinyl alcohol (PVA), hydroxypropyl methyl cellulose (HPMC, Hydroxy Propyl Methyl Cellulose), 2-hydroxy ethyl cellulose (2-hydroxy ethyl cellulos1e), methyl cellulose (methyl cellulose), ethyl cellulose (ethyl Cellulose) and polyethylene glycol (polyethyleneglycol), characterized in that at least one selected from the group consisting of, barrier film coating composition. The method of claim 1,
The water-soluble binder is polyvinyl alcohol (PVA), characterized in that the saponification degree of the polyvinyl alcohol (PVA) is 80 to 100 mol%, barrier film coating composition. delete The method of claim 1,
The nanoclay is montmorillonite, laponite, bentonite, hectorite, beidellite, nontronite, macadite, mica and fluorinated Composition for coating a barrier film, characterized in that at least one selected from the group consisting of mica. delete The method of claim 1,
The crosslinking agent is characterized in that it has two or more hydroxy groups, barrier film coating composition. The method of claim 1,
The crosslinking agent is dialdehyde, glyoxal, glutaraldehyde, polycarboxylic acid, citric acid, succinic acid, tartaric acid, ethyl Malonic acid (ethylmalonic acid) and adipic acid dihydrazide (adipic acid dihydrazide, ADH), characterized in that at least one selected from the group consisting of, barrier film coating composition. delete The method of claim 1,
The barrier film coating composition is characterized in that for manufacturing a food or pharmaceutical packaging material, a composition for coating a barrier film. Base film; And
A composition for coating a barrier film according to any one of claims 1, 2, 4, 5, 7, 9, 10 and 12 provided on the base film Barrier layer comprising a; Barrier film comprising a. The method of claim 13,
The base film is polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP; Polypropylene), polycarbonate (PC; polycarbonate), polymethyl methacrylate (PMMA; Poly(methyl methacrylate)) , Polyimide (PI), oriented polypropylene (OPP), biaxially oriented polypropylene (BOPP), polyethylene 2,6-dicarboxyl naphthalate (PEN; Polyethylene 2,6-dicarboxyl) naphthalate), polyethersulfone (PES), polyester, or polystyrene (PS). As a method for preparing a composition for coating a barrier film according to any one of claims 1, 2, 4, 5, 7, 9, 10 and 12,
Preparing cellulose nanofibers using pulp;
Adding a water-soluble binder and nano clay to the aqueous solution containing the cellulose nanofibers; And
A method for preparing a composition for coating a barrier film comprising a step of adding a crosslinking agent to the aqueous solution. The method of claim 15,
The method for producing a composition for coating a barrier film, characterized in that the cellulose nanofiber is produced using a fluid collision device. Preparing a base film; And
By applying the composition for coating a barrier film according to any one of claims 1, 2, 4, 5, 7, 9, 10 and 12 on the base film Barrier film manufacturing method comprising; forming a barrier layer. The method of claim 17,
Applying the composition for coating the barrier film is characterized in that it is carried out using a coma coating method, a barrier film manufacturing method.

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