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

Abstract

The present invention can provide a coating composition for a food packaging material, comprising: a natural product; a filler; an amine additive; and a surfactant. The invention can provide the preparation method of the coating composition for the food packaging material. The preparation method comprises the following steps: 1) dissolving a natural product in a solvent; 2) adding a filling agent and a surfactant; and 3) adding an amine additive, and heating while stirring.

Description

Technical Field

[0001] The present invention relates to a coating composition for food packaging materials using natural products and a method for preparing the same, and more particularly to a coating composition for food packaging materials using natural products and a method for preparing the same, the coating composition containing natural products, fillers, amine additives and surfactants, thereby suppressing the aggregation and gelation reactions of the natural products and exhibiting high liquid phase stability. Background Art

[0002] The existing synthetic resin films in the field of food packaging mainly include polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS), polyacrylonitrile (PAN) and the like as general materials. Currently, these polymers are prepared into solvent-based coating agents and then thin-film coated on the substrate to manufacture the final packaging film. Multilayer structures are usually used to manufacture composite films of various shapes to impart barrier properties suitable for product characteristics.

[0003] However, polymers such as EVOH and PVDC, which are mainly used as coating liquids, have low solubility, and therefore, most of them are solvent-based coating agents with a high organic solvent content. Such coating agents have continuously caused environmental problems such as low economic efficiency and large amounts of VOC emissions, as well as health issues for workers in composite film production and stable performance of the coating agents.

[0004] In connection with this, Patent Document 1 provides a biodegradable barrier film having barrier properties, which can be biodegraded when landfilled by including plate-like montmorillonite in a biodegradable resin, thereby preventing environmental pollution. In addition, Patent Document 2 provides a biodegradable film composition, which improves oxygen permeability by mixing an inorganic filler in a biodegradable resin.

[0005] However, when a biodegradable resin is used, there is a problem that a very large change in viscosity occurs during storage and distribution of the product, and decay occurs rapidly.

[0006] [Prior art literature]

[0007] [Patent Document]

[0008] (Patent Document 0001) Korean Patent Publication KR 10-2148518B (2020.08.20)

[0009] (Patent Document 0002) Korean Patent Publication No. KR 10-2023-0115728 (August 3, 2023) Summary of the invention

[0010] Problems to be solved by the invention

[0011] The present invention relates to a coating composition for food packaging materials, which solves the above-mentioned problems and suppresses aggregation and gelation phenomena caused by natural substances by using an amine additive and a surfactant at the same time, thereby extending the storage and circulation period.

[0012] The present invention relates to a method for preparing a coating composition for food packaging materials, which can exhibit high liquid phase stability by adding an amine additive and a surfactant in stages.

[0013] Methods used to solve problems

[0014] The present invention can provide a coating composition for food packaging materials, which comprises: a natural product; a filler; an amine additive; and a surfactant.

[0015] The natural product may 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.

[0016] The filler may include any one or more selected from the group consisting of sorbitol, fructose, sucrose, mannitol and glycerol.

[0017] The amine additive may 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.

[0018] The surfactant may include at least one selected from the group consisting of a cationic surfactant, an anionic surfactant, a nonionic surfactant, an amphoteric surfactant, and a lecithin-based surfactant.

[0019] The amine additive may be included in an amount of 10 to 30 parts by weight relative to 100 parts by weight of the natural product.

[0020] The surfactant may be included in an amount of 3 to 10 parts by weight relative to 100 parts by weight of the natural product.

[0021] The present invention provides a coating film for food packaging material, comprising: a substrate film; and a barrier film formed on the substrate film and formed from the coating composition for food packaging material.

[0022] The present invention provides a method for preparing a coating composition for food packaging materials, comprising the following steps: 1) dissolving a natural substance in a solvent; 2) adding a filler and a surfactant; and 3) adding an amine additive and heating while stirring.

[0023] The preparation method may include the following steps: cooling the mixed solution prepared in step 3), and then adding a silane coupling agent.

[0024] Effects of the Invention

[0025] The coating composition for food packaging material of the present invention suppresses the coagulation and gelation phenomena caused by natural products, thereby having high liquid phase stability. In addition, even if natural products are used, the viscosity does not change greatly during the storage and circulation of the product, so it does not decay quickly.

[0026] The coating film for food packaging material of the present invention has excellent light transmittance and transparency, and has improved oxygen permeability.

[0027] The method for preparing a coating composition for food packaging materials of the present invention can prepare a coating composition for food packaging materials that has high liquid phase stability and has a prolonged storage and distribution period. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The diagram schematically shows the process by which surfactants encapsulate natural substances and inhibit their reactivity. DETAILED DESCRIPTION

[0029] The technical terms used in this specification are used only to illustrate specific embodiments. It should be noted that these technical terms are not intended to limit the present invention. In addition, the technical terms used in this specification should be interpreted as the meanings commonly understood by ordinary technicians in the technical field to which the present invention belongs. Unless they are otherwise specifically defined in this specification, they cannot be interpreted in an overly general or overly narrowed sense. In addition, if the technical terms used in this specification are erroneous technical terms that cannot accurately describe the idea of ​​the present invention, the erroneous technical terms should be replaced and understood by technical terms that can be accurately understood by ordinary technicians in the field.

[0030] In addition, general terms used in this specification should be interpreted according to the definitions in dictionaries or according to the context, and should not be interpreted in an excessively narrow sense.

[0031] In addition, the description of the singular used in this specification includes the meaning of the plural number if no other meaning is generated in the context. In this application, the terms "composed of" and "including" should not be interpreted as necessarily including various constituent elements or various steps recorded in the specification, but should be interpreted as not including some of the constituent elements or some of the steps, or further including additional constituent elements or steps.

[0032] Hereinafter, the present invention will be described in more detail by way of examples, but the scope of the present invention is not limited to the following examples.

[0033] The coating composition for food packaging material according to one embodiment of the present invention may include: natural materials; fillers; amine additives; and surfactants. Specifically, the present invention relates to a coating composition for food packaging material, which uses amine additives and surfactants at the same time to inhibit the aggregation and gelation phenomena caused by natural materials, and prolongs the storage and circulation period.

[0034] As a natural product, protein is used. This protein is in the form of a polymer with amino acids bonded together, and contains a carboxyl group (-COOH) and an amine group (-NH 2 ), contains multiple peptide bonds (-O=C-NH-) in the middle of the chain, thus having excellent oxygen isolation properties.

[0035] The natural product may 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.

[0036] The coating composition for food packaging material contains a filler. When the coating composition is prepared, the filler is located in the gaps between the network structures formed by protein chains, thereby filling the gaps to improve the barrier properties and imparting a smooth surface effect.

[0037] The filler may include any one or more selected from the group consisting of sorbitol, fructose, sucrose, mannitol and glycerol.

[0038] The coating composition for food packaging material contains an amine additive to adjust the viscosity of the composition, thereby improving storage stability. The desired viscosity can be adjusted according to the content of the amine additive, and the viscosity is maintained at the initial viscosity during storage of the coating composition.

[0039] Functional groups contained in proteins can increase viscosity by forming hydrogen bonds with each other, but the present invention can prevent viscosity increase by blocking the functional groups using amine additives to block sites capable of forming hydrogen bonds.

[0040] Specifically, an amine additive is used in order to block hydrogen bonds between carboxyl groups and keto groups included in the protein structure.

[0041] When an amine additive is used, unlike when an acid compound is used as an additive, the effect of preventing viscosity increase due to blocking becomes the greatest. This may be because the amine additive reacts not only with the carboxyl group (-COOH) at the end of the protein, but also with the keto group (C=O) in the middle of the chain.

[0042] The amine additive may 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.

[0043] The amine additive may be included in an amount of 10 to 30 parts by weight relative to 100 parts by weight of the natural product, and preferably, may be included in an amount of 15 to 25 parts by weight. When the content of the amine additive is less than 10 parts by weight, the viscosity of the coating composition may change very quickly, and when it exceeds 30 parts by weight, the function of the natural product may decrease.

[0044] Since the coating composition for food packaging materials contains a surfactant, aggregation and gelation of natural substances can be suppressed, thereby improving the dispersibility, dispersion stability, storage stability, coating properties, and processability of the coating composition.

[0045] The natural substance as the main raw material of the coating composition is subjected to thermal and alkali denaturation to expose functional groups (e.g., -COO-), which causes aggregation and gelation. Therefore, in the present invention, the coating composition contains a surfactant to minimize the exposed functional groups, thereby preventing aggregation and gelation, and achieving high liquid phase stability. Figure 1 The diagram schematically shows the process by which surfactants encapsulate natural substances and inhibit their reactivity.

[0046] The surfactant may include at least one selected from the group consisting of a cationic surfactant, a nonionic surfactant, an amphoteric surfactant, and a lecithin-based surfactant.

[0047] The cationic surfactant may be alkylamine salts, amine salts such as polyamines and amino alcohol fatty acid derivatives, alkyl quaternary ammonium salts (dialkyldimethylammonium salts), aromatic quaternary ammonium salts (benzalkonium chloride), pyridinium salts, imidazolium salts or mixtures thereof.

[0048] The nonionic surfactant may be a primary or secondary alcohol nonionic surfactant containing 1 to 25 moles of ethylene oxide, an alkyl polyglucoside nonionic surfactant, a fatty acid amide nonionic surfactant, or a mixture thereof. Preferably, an alkyl polyglucoside nonionic surfactant having a linear or branched alkyl group with a carbon number of 8 to 22 may be used.

[0049] The amphoteric surfactant may be fatty acid amide betaine having 8 to 22 carbon atoms, amine having 8 to 22 carbon atoms, ie, alkyl amine oxide, or a mixture thereof.

[0050] The lecithin-based surfactant may include lecithin, hydrogenated lecithin, soybean lecithin, hydrogenated lecithin / C12-16 alcohol / palmitic acid or a mixture thereof.

[0051] The surfactant may be included in an amount of 3 to 10 parts by weight relative to 100 parts by weight of the natural product, and preferably, may be included in an amount of 5 to 7 parts by weight. When the content of the surfactant is less than 3 parts by weight, coating cannot be performed due to very high viscosity, and when the content exceeds 10 parts by weight, the functional groups that can be combined with the silane coupling agent are blocked due to excessive wrapping of the natural product by the surfactant, thereby causing a decrease in substrate adhesion.

[0052] As an embodiment of the present invention, the coating film for food packaging material is an oxygen barrier coating film, which may include: a substrate film; and a barrier film formed on the substrate film and formed from the coating composition for food packaging material.

[0053] The substrate film may be a film composed of polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polycarbonate (PC), polymethyl methacrylate (PMMA), polyimide (PI), oriented polypropylene (OPP), biaxially oriented polypropylene (BOPP), polyethylene 2,6-naphthalate (PEN), polyether sulfone (PES), polyester or polystyrene (PS) and the like.

[0054] The coating film for a food packaging material may further include a nylon film formed on the barrier film.

[0055] The production of the coating film for food packaging material comprises the following steps: coating the coating composition for food packaging material on a substrate film with a certain thickness; and drying the substrate film coated with the coating composition.

[0056] The coating film for food packaging material has suitable light transmittance and haze, wherein the light transmittance is 89 to 90%, the haze value is less than 5%, and the oxygen permeability is about 0.5 g / m 2 *day, so it has high oxygen barrier properties.

[0057] As one embodiment of the present invention, a method for preparing a coating composition for food packaging materials comprises the following steps: 1) dissolving a natural substance in a solvent; 2) adding a filler and a surfactant; and 3) adding an amine additive and heating while stirring, thereby providing a coating composition for food packaging materials having high liquid phase stability.

[0058] The step 1) is a step of slowly adding the natural product to the solvent while stirring. At this time, distilled water or purified water is preferably used as the solvent.

[0059] The step 2) is a step of adding a filler and a surfactant to prevent the natural product from agglomerating again after the stirring in the step 1) is completed. In particular, the preparation method can suppress the agglomeration and gelation of the natural product by adding a surfactant, and can improve the dispersibility, dispersion stability, storage stability, coating property and processability of the coating composition.

[0060] The step 3) is a step of diluting the amine additive in a solvent. After adding the amine additive and adjusting the pH of the solution to above 8, the temperature is raised to 80 to 100° C. while stirring, and heated for 30 to 120 minutes, preferably, for 30 to 60 minutes.

[0061] The method for preparing the coating composition for food packaging materials may include the following steps: cooling the mixed solution prepared in step 3), and then adding a silane coupling agent.

[0062] By using a silane coupling agent, it is possible to provide excellent adhesion between the substrate film of the coating film for food packaging materials and the barrier film formed by the coating composition. From the viewpoint of ensuring stable oxygen barrier properties, the silane coupling agent is preferably added in a ratio of silane coupling agent to protein of 1:1 to 1:10. Specifically, aminosilane, epoxysilane, acrylic silane, vinylsilane, methylsilane, etc. can be used as the silane coupling agent.

[0063] Example 1: Analysis based on whether amine additives are contained

[0064] (1) Preparation of coating composition

[0065] 5 g of whey protein isolate (WPI) was slowly added to 86.25 g of distilled water under stirring, and then sorbitol was added in a ratio of sorbitol to whey protein isolate of 1:1 (wt%), and 0.35 g of dialkyldimethylammonium salt was added.

[0066] Then, 1.25 g of the amine additives of Examples 1-1 to 1-3 or the acid additives of Comparative Examples 1-2 to 1-4 in Table 1 were added, stirred at 300 rpm using a mechanical stirrer, and heated to 90° C. for 30 minutes. After the mixed solution that had completed the heating reaction was cooled, the hydrolyzed silane coupling agent was added in a ratio of 1:1 (wt%) to the whey protein isolate.

[0067]

Table 1

[0068] Additive Type Example 1-1 Ethylenediamine Example 1-2 Triethanolamine Examples 1-3 Triethylamine Comparative Example 1-1 No additives added Comparative Example 1-2 Acetic acid Comparative Examples 1-3 hydrochloric acid Comparative Examples 1-4 sulfuric acid

[0069] (2) Manufacturing coating film

[0070] After the substrate film (PET) was sufficiently close to the glass plate of the coating machine, about 1 to 2.5 g of the coating composition prepared according to Example 1 and Comparative Example 1 was dropped on the upper part of the substrate film, and the coating composition was applied to the substrate film with a certain 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, thereby manufacturing the coating films of Example 1 and Comparative Example 1.

[0071] Experimental Example 1

[0072] (1) Measuring viscosity

[0073] For the coating compositions prepared according to Example 1 and Comparative Example 1, the viscosity was measured (spindle: No. 3, rpm: 100 rpm) at normal temperature and humidity conditions (20±5°C, 55±5%) using a DV-± viscometer from Brookfield as a storage stability scale. The initial viscosity at a temperature of 24°C and a humidity of 51%, the viscosity after storage for 2 weeks, and the viscosity after 2 months were measured and are shown in [Table 2].

[0074] (2) Measurement of transmittance and haze

[0075] The light transmittance (%) and haze (%) of the coating films prepared according to Example 1 and Comparative Example 1 were measured using a haze meter (NDH-7000) and are shown in [Table 2]. The coating films prepared immediately after the coating agent was prepared and the coating films prepared after storage for 2 weeks and 2 months were compared.

[0076] (3) Measure oxygen transmission rate (OTR)

[0077] For the coating films prepared according to Example 1 and Comparative Example 1, oxygen permeability tester (OX-TRAN 2 / 22H) was used to measure the oxygen permeability of the coating films at a temperature of 23°C, a humidity of 0% and a sample area of ​​50 cm. 2 , O 2 The amount of oxygen permeating the coating film within a certain period of time at 100% is shown in [Table 2]. Similar to the optical characteristics, the coating film produced immediately after the coating agent was prepared and the coating film produced after storage for 2 weeks and 2 months were compared.

[0078]

Table 2

[0079]

[0080] As shown in [Table 2], it can be confirmed that the viscosity change rate is low and the storage stability is excellent when an amine additive is added as in Examples 1-1 to 1-3, compared with the case where no additive is added as in Comparative Example 1-1 or the case where an acid additive is 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 in which the entire reactant solidifies occurs after 2 weeks and 2 months, making it impossible to measure with a viscometer.

[0081] It can be confirmed that the coating films for food packaging materials according to Examples 1-1 to 1-3 have certain transmittance and haze, with a transmittance of about 89% and a haze of about 4%, which are suitable for food packaging materials, and their oxygen barrier properties are also about 0.5 g / m 2 * Day, it has excellent barrier properties and it is confirmed that the initial physical properties can be maintained to a certain extent.

[0082] However, in the case of Comparative Examples 1-1 to 1-4, precipitation occurred on the film appearance over time, resulting in spots. Therefore, it was determined that Examples 1-1 to 1-3 using amine additives as additives could ensure the storage stability of the coating composition and were suitable as conditions for satisfying the required physical properties.

[0083] Example 2: Analysis based on whether surfactant is contained

[0084] (1) Preparation of coating composition

[0085] 5 g of whey protein isolate (WPI) was slowly added to 86.25 g of distilled water under stirring, and then sorbitol was added in a ratio of sorbitol to whey protein isolate of 1:1 (wt%), and surfactants of Examples 2-1 to 2-5 described in [Table 3] were added according to the content.

[0086] Then, 1.25 g of ethylenediamine was added, and the mixture was stirred at 300 rpm using a mechanical stirrer, and the temperature was raised to 90° C. and heated for 30 minutes. After the mixed solution that had completed the heating reaction was cooled, the hydrolyzed silane coupling agent was added in a ratio of 1:1 (wt%) to the whey protein isolate.

[0087] 【Table 3

[0088]

[0089] (2) Preparation of coating film

[0090] By the same method as in Example 1, a coating film was produced.

[0091] Experimental Example 2

[0092] (1)Measure viscosity, transmittance, haze, and oxygen permeability (OTR)

[0093] The viscosity, light transmittance, haze, and oxygen permeability (OTR) of the coating films produced according to Example 2 and Comparative Example 2 were measured by the same method as in Experimental Example 1, and are shown in [Table 4].

[0094] (2) Adhesion to substrate

[0095] The substrate adhesion of the coating films produced according to Example 2 and Comparative Example 2 was measured based on ASTM D 3359 (Standard Test Methods for Rating Adhesion by Tape Test) and is shown in [Table 4].

[0096] 【Table 4

[0097]

[0098] As shown in [Table 4], it was confirmed that the addition of a surfactant as in Examples 2-1 to 2-5 had a significant effect on maintaining viscosity, compared with the case where no surfactant was included as in Comparative Example 2-1.

[0099] In addition, the coating films for food packaging materials according to Examples 2-1 to 2-5 have certain light transmittance, haze, and oxygen permeability, and can maintain the initial physical properties to a certain extent after a certain period of time.

[0100] In particular, Example 2-1 showed excellent results compared to Example 2-2, and Example 2-4 showed excellent results compared to Example 2-3 and Example 2-5.

[0101] On the contrary, in the case of Comparative Example 2-1, it can be seen that the light transmittance thereof sharply decreases with the passage of time, and the haze and oxygen permeability increase rapidly.

[0102] Therefore, when preparing the coating composition, Examples 2-1 to 2-5 in which a surfactant is added can minimize the exposed functional groups, thereby preventing aggregation and gelation phenomena, and are judged to be suitable for improving the stability of the liquid phase.

Claims

1. A coating composition for food packaging material, wherein: The coating composition for food packaging material comprises: natural matter; filler; amine additive; and surfactant.

2. The coating composition for food packaging material according to claim 1, wherein The natural product includes 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.

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

4. The coating composition for food packaging material according to claim 1, wherein The amine additives 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.

5. The coating composition for food packaging material according to claim 1, wherein The surfactant includes at least one selected from the group consisting of a cationic surfactant, an anionic surfactant, a nonionic surfactant, an amphoteric surfactant and a lecithin surfactant.

6. The coating composition for food packaging material according to claim 1, wherein The amine additive is included in an amount of 10 to 30 parts by weight relative to 100 parts by weight of the natural product.

7. The coating composition for food packaging material according to claim 1, wherein The surfactant is included in an amount of 3 to 10 parts by weight relative to 100 parts by weight of the natural product.

8. A coating film for food packaging material, wherein: The coating film for food packaging material comprises: a substrate film; and A barrier film formed on the substrate film, the barrier film being formed from the coating composition for food packaging material according to any one of claims 1 to 7.

9. A method for preparing a coating composition for food packaging material, wherein: The preparation method of the coating composition for food packaging material comprises the following steps: 1) Dissolve natural substances in solvents; 2) adding fillers and surfactants; and 3) Add an amine additive and heat while stirring.

10. The method for preparing the coating composition for food packaging material according to claim 9, wherein: The preparation method of the coating composition for food packaging material comprises the following steps: After cooling the mixed solution prepared in step 3), a silane coupling agent is added.

Images