Coating composition for food packaging material using natural product and production method thereof

Abstract

To provide a coating composition for food packaging materials that suppresses coagulation and gelation phenomenon generated by natural products and extends storage and circulation life.SOLUTION: The present invention can provide a coating composition for food packaging materials that includes natural products, a filler, an amine-based additive, and a surfactant, and can offer a method for producing a coating for food packaging materials that includes (1) a step of dissolving the natural product in a solvent, (2) a step of adding the filler and the surfactant, and (3) a step of adding the amine-based additive and heating while stirring.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a coating composition for food packaging materials using natural products and a method for producing the same. More specifically, by including natural products, fillers, amine-based additives, and surfactants, the present invention relates to a coating composition that suppresses the aggregation and gelation reactions of natural products and exhibits high liquid stability, and a method for producing the same.

Background Art

[0002] Conventional synthetic resin films in the food packaging field mainly include polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS), polyacrylonitrile (PAN), etc., which are general-purpose materials. After producing a polymer as a solvent-based coating agent, a thin film coating is applied on a substrate to produce a final packaging film. Usually, in a multilayer structure, various composite film forms are produced to provide a barrier property suitable for product characteristics.

[0003] However, polymers such as EVOH and PVDV, which are mainly used as coating liquids, have low solubility, so most of the solvent-based coating agents contain a high content of organic solvents. Such coating agents have caused continuous problems in terms of high cost, environmental problems due to the release of a large amount of VOCs, and the health and stability of workers manufacturing composite films.

[0004] Regarding this, Patent Document 1 provides a biodegradable barrier film that contains plate-like montmorillonite in a biodegradable resin and has a barrier property that can be biodegraded during embedding and prevent environmental pollution. In addition, Patent Document 2 provides a biodegradable film composition in which an inorganic filler is mixed with a biodegradable resin and the oxygen permeability is improved.

[0005] However, when using a biodegradable resin, there is a problem that a drastic viscosity change occurs during the storage and distribution period of the product, and rapid spoilage occurs.

Prior Art Documents

Patent Documents

[0006] [Patent Document 1] Korean Patent Registration Bulletin 10-2148518B (August 20, 2020) [Patent Document 2] Korean Patent Publication Bulletin 10-2023-0115728 (August 3, 2023) [Summary of the Invention] [Problems to be Solved by the Invention]

[0007] The present invention relates to a coating composition for a food packaging material that solves the above problems, uses an amine-based additive and a surfactant at the same time, suppresses the aggregation and gelation phenomena generated by natural products, and extends the storage and distribution periods.

[0008] The present invention relates to a manufacturing method for providing a coating composition for a food packaging material that exhibits high liquid stability by sequentially adding a filler, an amine-based additive, and a surfactant to natural products. [Means for Solving the Problems]

[0009] The present invention can provide a coating composition for a food packaging material containing a natural product, a filler, an amine-based additive, and a surfactant.

[0010] The natural product can contain any one or more selected from the group consisting of isolated whey protein (Whey protein isolate, WPI), concentrated whey protein (Whey protein Concentrate, WPC), soy protein (soy protein isolate, SPI), rice protein (rice protein isolate, RPI), oatmeal protein (oat protein isolate, OPI), pea protein (peaprotein isolate, PPI), casein, sodium caseinate, corn zein, gelatin, wheat protein (Gluten), dextrins, carrageenans, chitosan, starch, and cellulose (Cellulose).

[0011] The filler can contain any one or more selected from the group consisting of sorbitol, fructose, sucrose, mannitol, and glycerol (Glycerol).

[0012] The amine-based additive can contain any one or more selected from the group consisting of monoethylamine, monoethanolamine, monoisopropanolamine, diethylamine, diethanolamine, triethylamine, triethanolamine, dimethylethanolamine, propylamine, dodecylamine, cyclohexylamine, ethylenediamine, pyrrolidine, N,N-dimethyldodecylamine, N,N-dimethyloctadecylamine, and N,N-dimethylcyclohexylamine.

[0013] The surfactant can contain any one or more selected from the group consisting of cationic surfactants, anionic surfactants, nonionic surfactants, amphoteric surfactants, and lecithin-based surfactants.

[0014] The amine-based additive may be contained in an amount of 10 to 30 parts by weight with respect to 100 parts by weight of the natural product.

[0015] The surfactant may be contained in an amount of 3 to 10 parts by weight with respect to 100 parts by weight of the natural product.

[0016] The present invention provides a coating film for a food packaging material, including a base film and a barrier film formed on the base film and formed from the coating composition for a food packaging material.

[0017] The present invention provides a method for manufacturing a coating for a food packaging material, including: (1) a step of dissolving a natural product in a solvent; (2) a step of adding a filler and a surfactant; and (3) a step of adding an amine-based additive and heating while stirring.

[0018] The manufacturing method may include a step of adding a silane coupling agent after cooling the mixed solution produced in the step (3).

Effects of the Invention

[0019] The coating composition for a food packaging material of the present invention suppresses the aggregation and gelation phenomena generated by the natural product and has high liquid stability. Further, despite using a natural product, no drastic viscosity change occurs during the storage and distribution periods of the product, so rapid spoilage does not occur.

[0020] The coating film for a food packaging material of the present invention has excellent light transmittance and transparency and has improved oxygen permeability.

[0021] Through the method for manufacturing the coating composition for a food packaging material of the present invention, not only high liquid stability but also a coating composition for a food packaging material with an extended storage and distribution period can be manufactured.

Brief Description of the Drawings

[0022]

Figure 1

Mode for Carrying Out the Invention

[0023] It should be noted that the technical terms used in this specification are merely used to explain specific embodiments and are not intended to limit the present invention. Also, the technical terms used in this specification should be interpreted as meanings generally understandable by those with ordinary knowledge in the technical field to which the present invention pertains, unless otherwise defined specifically in this specification, and should not be interpreted in an overly comprehensive or narrowed meaning. Furthermore, if the technical terms used in this specification are incorrect technical terms that cannot accurately represent the idea of the present invention, they should be replaced with technical terms that can be correctly understood by ordinary technicians so as to be understood.

[0024] Also, general terms used in the present invention should be interpreted as defined in a dictionary or according to the context before and after, and should not be interpreted in an overly narrowed meaning.

[0025] Furthermore, the singular expressions used in this specification shall include plural expressions unless the context clearly indicates otherwise. In this application, terms such as "consisting of" or "including" should not necessarily be interpreted as including various components or a plurality of steps described in the specification. Among them, some components or some steps may not be included, or additional components or steps may be further included and should be interpreted as such.

[0026] Hereinafter, the present invention will be further specifically examined through examples, but the scope of the present invention is not limited by the following examples.

[0027] A coating composition for a food packaging material according to an embodiment of the present invention can include a natural product, a filler, an amine-based additive, and a surfactant. Specifically, by using an amine-based additive and a surfactant simultaneously, an aggregation and gelation phenomenon generated by the natural product is suppressed, and the present invention relates to a coating composition for a food packaging material with an extended storage and distribution period.

[0028] As the natural product, in the form of a polymer to which amino acids are bound, a carboxyl group (-COOH) and an amine group (-NH 2 ) are respectively present at the molecular chain terminals, and a large number of peptide bonds (-O = C-NH-) are included in the middle of the chain, and a protein excellent in oxygen barrier properties is used.

[0029] The natural product can include any one or more selected from the group consisting of whey protein isolate (WPI), whey protein concentrate (WPC), soy protein isolate (SPI), rice protein isolate (RPI), oat protein isolate (OPI), pea protein isolate (PPI), casein, sodium caseinate, corn zein, gelatin, gluten, dextrins, carrageenans, chitosan, starch, and cellulose.

[0030] The coating composition for the food packaging material includes a filler. During the production of the coating composition, the filler is located in the voids between the network structures formed by the protein chains, fills the voids, and enhances the barrier properties, thereby having the effect of smoothing the surface.

[0031] The filler can include any one or more selected from the group consisting of sorbitol, fructose, sucrose, mannitol, and glycerol.

[0032] The coating composition for food packaging materials contains an amine-based additive and can enhance storage stability by adjusting the viscosity of the composition. It is possible to adjust the desired viscosity according to the content of the amine-based additive, and maintain the viscosity at the initial viscosity during the storage of the coating composition.

[0033] The functional groups contained in the protein may form hydrogen bonds with each other and increase the viscosity. However, by using an amine-based additive, the functional groups can be blocked, preventing the sites where hydrogen bonds can form, thereby preventing an increase in viscosity.

[0034] Specifically, an amine-based additive is used to block the hydrogen bond between the carboxyl group and the ketone group contained in the protein structure.

[0035] When an amine-based additive is used, it is recognized that the effect of preventing an increase in viscosity due to blocking is maximized, which is different from the case when an acid compound is used as an additive. This is considered to act not only on the carboxyl group (-COOH) at the end of the protein but also on the ketone group (C=O) present in the middle of the chain.

[0036] The amine-based additive can include any one or more selected from the group consisting of monoethylamine, monoethanolamine, monoisopropanolamine, diethylamine, diethanolamine, triethylamine, triethanolamine, dimethylethanolamine, propylamine, dodecylamine, cyclohexylamine, ethylenediamine, pyrrolidine, N,N-dimethyldodecylamine, N,N-dimethyloctadecylamine, and N,N-dimethylcyclohexylamine.

[0037] The amine-based additive can be contained in an amount of 10 to 30 parts by weight, preferably 15 to 25 parts by weight, per 100 parts by weight of the natural product. When the amine-based additive is contained in an amount of less than 10 parts by weight, the viscosity of the coating composition changes rapidly. When it exceeds 30 parts by weight, the function of the natural product may decrease.

[0038] By containing a surfactant, the coating composition for food packaging materials can suppress the aggregation and gelation phenomena of the natural product, thereby improving the dispersibility, dispersion stability, storage stability, coating property, and processability of the coating composition.

[0039] The aggregation and gelation phenomena occur due to the exposed functional groups (e.g., -COO-) while denaturing the natural product, which is the main raw material of the coating composition, with heat and a base. Here, in the present invention, by containing a surfactant in the coating composition, the exposed functional groups can be reduced to the maximum extent, thereby preventing the aggregation and gelation phenomena and achieving high liquid stability. FIG. 1 illustrates the process of suppressing the reactivity by surrounding the natural product with a surfactant.

[0040] The surfactant can include any one or more selected from the group consisting of cationic surfactants, nonionic surfactants, amphoteric surfactants, and lecithin-based surfactants.

[0041] As the cationic surfactant, amine salts such as alkylamine salts, polyamines, and amino alcohol fatty acid derivatives, alkyl quaternary ammonium salts (dialkyldimethylammonium salts), aromatic quaternary ammonium salts (alkyldimethylbenzylammonium salts), pyridinium salts, imidazolium salts, or mixtures thereof can be used.

[0042] As the nonionic surfactant, a primary or secondary alcohol-based nonionic surfactant containing 1 to 25 moles of ethylene oxide, an alkyl polyglycoside-based nonionic surfactant, a fatty acid amide-based nonionic surfactant, or a mixture thereof can be used. Preferably, an alkyl polyglycoside-based nonionic surfactant having a linear or branched alkyl group with 8 to 22 carbon atoms can be used.

[0043] As the amphoteric surfactant, a fatty acid amide-based betaine having 8 to 22 carbon atoms, an amine-based alkylamine oxide having 8 to 22 carbon atoms, or a mixture thereof can be used.

[0044] As the lecithin-based surfactant, lecithin, hydrogenated lecithin, soybean phospholipid, hydrogenated lecithin / C12-16 alcohol / palmitic acid, or a mixture thereof can be used.

[0045] As the surfactant, it can be contained in an amount of 3 to 10 parts by weight, preferably 5 to 7 parts by weight, based on 100 parts by weight of the natural product. When the surfactant is contained in an amount of less than 3 parts by weight, coating itself is impossible due to extremely high viscosity. When it exceeds 10 parts by weight, the surfactant will excessively surround the natural product, blocking the functional groups that can bind to the silane coupling agent, resulting in poor adhesion to the substrate.

[0046] A coating film for a food packaging material according to an embodiment of the present invention is an oxygen barrier coating film, which can include a substrate film and a barrier film formed on the substrate film and formed from the coating composition for a food packaging material.

[0047] The base film can be a film made of polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polycarbonate (PC), polymethyl methacrylate (PMMA), polyimide (PI), stretched polypropylene (OPP), biaxially stretched polypropylene (BOPP), polyethylene 2,6-dicarboxylate naphthalate (PEN), polyethersulfone (PES), polyester or polystyrene (PS), etc.

[0048] The coating film for food packaging materials can further include a nylon film formed on the barrier film.

[0049] The coating film for food packaging materials is manufactured by comprising a step of applying the coating composition for food packaging materials on a base film with a certain thickness, and a step of drying the base film coated with the coating composition.

[0050] The transmittance of the coating film for food packaging materials is 89 - 90%, having appropriate transmittance and haze with a haze value of 5% or less, and the oxygen transmission rate is about 0.5 g / m 2 *day, having high barrier properties against oxygen.

[0051] The manufacturing method of the coating composition for food packaging materials which is an embodiment of the present invention includes: (1) a step of dissolving a natural product in a solvent; (2) a step of adding a filler and a surfactant; and (3) a step of adding an amine-based additive and heating while stirring, and can provide a coating composition for food packaging materials having high liquid stability.

[0052] The step (1) is a step of slowly adding a natural product to a solvent while stirring. At this time, it is preferable to use distilled water or purified water as the solvent.

[0053] The step (2) is a step of adding a filler and a surfactant after the stirring in the step (1) is completed to prevent the natural product from agglomerating again. In particular, by adding a surfactant, the manufacturing method can suppress the aggregation and gelation phenomena of the natural product, and can improve the dispersibility, dispersion stability, storage stability, coating property, and processability of the coating composition.

[0054] The step (3) is a step of diluting an amine-based additive in a solvent. After adding the amine-based additive and adjusting the pH of the solution to 8 or higher, stirring is performed, and the temperature is raised to 80 - 100 °C and heated for 30 - 120 minutes, preferably 30 - 60 minutes.

[0055] The manufacturing method of the coating composition for food packaging materials may include a step of adding a silane coupling agent after cooling the mixed solution produced in the step (3).

[0056] By using a silane coupling agent, excellent adhesion can be achieved between the base film of the coating film for food packaging materials and the barrier film formed by the coating composition. The silane coupling agent is preferably added in a ratio of 1:1 to 1:10 with the protein in terms of ensuring stable oxygen barrier properties. Specifically, as the silane coupling agent, aminosilane, epoxy silane, acrylic silane, etc. can be used.

[0057] Example 1: Examination based on whether or not an amine-based additive is contained (1) Manufacture of coating composition After slowly adding 5 g of whey protein isolate (WPI) to 86.25 g of distilled water under stirring, sorbitol was added at a ratio of 1:1 (wt%) with the whey protein, and 0.35 g of dialkyldimethylammonium salt was added.

[0058] After that, 1.25 g of each of the amine-based additives in Examples 1-1 to 1-3 or the acid additives in Comparative Examples 1-2 to 1-4 in Table 1 was added, and the mixture was stirred at 300 rpm using a mechanical stirrer and heated to 90 °C for 30 minutes. After cooling the mixed solution after the heating reaction was completed, the hydrolyzed silane coupling agent was added at a ratio of 1:1 (wt%) to whey protein.

[0059]

Table 1

[0060] (2) Production of coating film After closely adhering the base film (PET) to the glass plate of the coater, about 1 to 2.5 g of the coating compositions produced in Example 1 and Comparative Example 1 was dropped onto the upper part of the base film, and the coating composition was applied to the base film with a constant thickness using an applicator (YBA-5). The film coated with the coating composition was dried at 120 °C for 1 to 2 minutes using a hot air dryer to produce the coating films of Example 1 and Comparative Example 1.

[0061] Experimental Example 1 (1) Viscosity measurement Regarding the coating compositions produced in Example 1 and Comparative Example 1, as a measure of storage stability, the viscosity was measured at normal temperature and normal humidity conditions (20 ± 5 °C, 55 ± 5%) using a Brookfield DV-± viscometer (spindle: No. 3, rpm: 100 rpm). The initial viscosity at a temperature of 24 °C and a humidity of 51%, and the viscosities after 2 weeks and 2 months of storage were measured, and the measurement results are shown in Table 2.

[0062] (2) Transmittance and haze measurement For the coating films produced in Example 1 and Comparative Example 1, the light transmittance (%) and haze (%) including the base film were measured with a haze meter (NDH-7000), and the measurement results are shown in Table 2. The coating films produced immediately after the production of the coating agent were compared with those produced 2 weeks and 2 months after storage.

[0063] (3) Oxygen Transmission Rate (OTR) Measurement For the coating films produced in Example 1 and Comparative Example 1, using an oxygen permeability tester (OX-TRAN 2 / 22H), at a temperature of 23 °C, a humidity of RH 0%, and a sample area of 50 cm 2 , O 2 100%, the amount of oxygen permeating through the coating film within a certain period of time was measured, and the measurement results are shown in Table 2. Similar to the optical properties, the coating films produced immediately after the production of the coating agent were compared with those produced 2 weeks and 2 months after storage.

[0064]

Table 2

[0065] As shown in Table 2, when an amine-based additive was added as in Examples 1-1 to 1-3, the viscosity change rate was lower and the storage stability was better than when no additive was added as in Comparative Example 1-1 or when an acid additive was added as in Comparative Examples 1-2 to 1-4. In particular, in the case of Comparative Examples 1-1 to 1-4, a gelation phenomenon occurred in which the entire reactant became hard after 2 weeks and 2 months, and it was impossible to measure with a viscometer.

[0066] The transmittance of the coating films for food packaging materials according to Examples 1-1 to 1-3 was about 89%, and the haze was about 4%, which is appropriate for use as food packaging materials, having a certain light transmittance and haze, and the oxygen transmission rate was also about 0.5 g / m 2It was found to have excellent barrier properties as *day, and it was confirmed that the initial physical properties were maintained to some extent.

[0067] However, in the case of Comparative Examples 1-1 to 1-4, precipitation occurred on the film appearance over time, resulting in spots. Therefore, Examples 1-1 to 1-3 to which an amine-based additive was applied as an additive were judged to be preferable as conditions for satisfying the necessary physical properties while ensuring the storage stability of the coating composition.

[0068] Example 2: Examination based on whether or not a surfactant is contained (1) Production of coating composition After slowly adding 5 g of whey protein (Whey protein isolate, WPI) to 86.25 g of distilled water with stirring, sorbitol and whey protein were added at a ratio of 1:1 (wt%), and the surfactants of Examples 2-1 to 2-5 shown in Table 3 were added according to the content.

[0069] Thereafter, 1.25 g of triethylamine was added, and the mixture was stirred at 300 rpm using a mechanical stirrer and heated to 90 °C for 30 minutes. After cooling the mixed solution after the heating reaction was completed, a hydrolyzed silane coupling agent and whey protein were added at a ratio of 1:1 (wt%).

[0070]

Table 3

[0071] (2) Production of coating film The coating film was produced in the same manner as in the method of Example 1.

[0072] Experimental Example 2 (1) Measurement of viscosity, transmittance, haze, and oxygen transmission rate (OTR) In the same manner as in Experimental Example 1, the viscosity, transmittance, haze, and oxygen transmission rate (OTR) of the coating films produced in Example 2 and Comparative Example 2 were measured, and the measurement results are shown in Table 4.

[0073] (2) Substrate adhesion The substrate adhesion to the coating films produced in Example 2 and Comparative Example 2 was measured through ASTM D 3359 (Standard Test Methods for Rating Adhesion by Tape Test), and the measurement results are shown in Table 4.

[0074]

Table 4

[0075] As shown in Table 4, it can be confirmed that when a surfactant is added as in Examples 2-1 to 2-5, the effect on viscosity maintenance is superior to that when no surfactant is included as in Comparative Example 2-1.

[0076] Also, the coating films for food packaging materials according to Examples 2-1 to 2-5 had a certain light transmittance, haze, and oxygen transmission rate, and the initial physical properties were maintained to a certain extent even after the passage of time.

[0077] In particular, Example 2-1 showed superior results compared to Example 2-2, and Example 2-4 showed superior results compared to Examples 2-3 and 2-5.

[0078] On the other hand, in the case of Comparative Example 2-1, it can be seen that the light transmittance decreased rapidly with the passage of time, and the haze and oxygen transmission rate increased rapidly.

[0079] Therefore, it is judged that Examples 2-1 to 2-5 in which a surfactant is added during the production of the coating composition can minimize the exposed functional groups, thereby preventing aggregation and gelation phenomena, which is preferable for improving liquid stability.

Claims

1. A coating composition for food packaging comprising a natural product, a filler, an amine-based additive, and a surfactant.

2. The natural products include whey protein isolate (WPI), whey protein concentrate (WPC), soy protein isolate (SPI), rice protein isolate (RPI), oat protein isolate (OPI), pea protein isolate (PPI), casein, sodium caseinate, corn protein isolate (Corn protein isolate), and soy protein isolate (SOPI).

2. The coating composition for food packaging materials according to claim 1, comprising at least one selected from the group consisting of wheat protein, zein, gelatin, gluten, dextrin, carrageenan, chitosan, starch, and cellulose.

3. 2. The coating composition for food packaging materials according to claim 1, wherein the filler comprises at least one selected from the group consisting of sorbitol, fructose, sucrose, mannitol, and glycerol.

4. 2. The coating composition for food packaging materials according to claim 1, wherein the amine-based additive comprises at least one selected from the group consisting of monoethylamine, monoethanolamine, monoisopropanolamine, diethylamine, diethanolamine, triethylamine, triethanolamine, dimethylethanolamine, propylamine, dodecylamine, cyclohexylamine, ethylenediamine, pyrrolidine, N,N-dimethyldodecylamine, N,N-dimethyloctadecylamine, and N,N-dimethylcyclohexylamine.

5. 2. The coating composition for food packaging materials according to claim 1, wherein the surfactant comprises at least one selected from the group consisting of cationic surfactants, anionic surfactants, nonionic surfactants, amphoteric surfactants, and lecithin-based surfactants.

6. The coating composition for food packaging materials according to claim 1, wherein the amine-based additive is contained in an amount of 10 to 30 parts by weight based on 100 parts by weight of the natural product.

7. 2. The coating composition for food packaging materials according to claim 1, wherein the surfactant is contained in an amount of 3 to 10 parts by weight based on 100 parts by weight of the natural product.

8. A base film; A barrier film formed on the base film and made of the coating composition for food packaging materials according to any one of claims 1 to 7; A coating film for food packaging materials, comprising:

9. (1) dissolving a natural product in a solvent; (2) adding a filler and a surfactant; (3) adding an amine-based additive and heating while stirring; A method for producing a coating for food packaging, comprising:

10. The method for producing a coating for food packaging materials according to claim 9, further comprising the step of adding a silane coupling agent after cooling the mixture produced in step (3).

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