KR20220000682A - Coating composition comprising protein with improved water resistance and manufacturing method of the same - Google Patents

Abstract

The present invention provides a coating composition comprising a protein with improved water resistance, which is based on a protein as a main component and can control the viscosity and concentration to a level suitable for forming a film, inhibits decomposition of the protein to improve durability and barrier properties while overcoming an odor occurring problem when being manufactured in a film-type coating layer or food packaging material, and ensures excellent water resistance; and a method for manufacturing the same.

Description

Coating composition containing protein with improved water resistance and manufacturing method thereof

The present invention relates to a method for improving the water resistance of a high molecular protein, a composition for coating comprising a protein with improved water resistance, and a method for manufacturing the same, and more particularly, a high molecular protein and a low molecular weight lipophilic filler (plasticizer) as main components It is a natural product-based coating composition that can control the viscosity and concentration of the composition to a level suitable for forming a film, and inhibits protein decay, and uses the composition as a film-type coating layer or a dry coating film when manufactured as a food packaging material. It can improve the durability and water resistance of natural products, and while maintaining the excellent oxygen barrier properties unique to natural products, it prevents the change over time when the viscosity increases during storage and distribution of the liquid coating composition, and the problem of odors due to decay. It relates to a coating composition comprising a protein having improved water resistance and a method for producing the same.

Recently, various processed foods such as retort foods, lunch boxes, instant noodles, and instant rice, which are easy to store and cook, have been released. Packaging is done by sealing with a cover in the form of a film or by putting food in a food packaging material in the form of a film and sealing the entrance.

Referring to FIG. 1, the conventional barrier film for food packaging, which is a barrier film used at this time, has a thermal adhesive layer 1 disposed at the bottom as a lower layer in contact with food, and an intermediate layer on the upper surface of the thermal adhesive layer 1, oxygen and moisture. It may have a structure in which the blocking layer 2 is disposed, and the printing and finishing layer 3 is disposed on the upper surface of the oxygen and moisture blocking layer 2 .

At this time, it is important to maintain the freshness of the food for a long time by providing an appropriate barrier to moisture or air to the film-type cover and food packaging material. Materials used for conventional film-type covers and food packaging materials are largely metal foil, such as aluminum foil, processed paper, or plastic.

Among them, metal foil has high mechanical strength and high barrier properties against external environments such as moisture, oxygen and ultraviolet rays, but has a problem in that it is heavier than processed paper or plastic and rusts when in contact with acidic food, making it difficult to store for a long time. Processed paper has the advantages of low price and easy recycling, but it is weak against moisture, so there is a limit to the types of food that can be packaged. In the case of plastics, despite the advantages of light weight, excellent physical strength, and almost no corrosion or oxidation, microplastics are generated during disposal after use, which negatively affects the environment.

In order to solve the problem of the conventional coating composition used for such food packaging materials, attempts are being made to use a biodegradable or biodegradable synthetic resin with rotting properties as a material. However, the biodegradable or biodegradable synthetic resin has a barrier property that is inferior to that of the general synthetic resin, and thus the thickness of the packaging material must be increased to realize the same barrier performance. This causes a problem of increasing the weight and cost of the packaging material. In addition, biodegradable or biodegradable synthetic resins are only applied to some special fields because the manufacturing process is difficult and the manufacturing cost is high, and in fact, synthetic resins having rotting properties are not widely used industrially.

In addition, most biodegradable or biodegradable synthetic resins in fields such as food packaging materials, not industrial products, do not realize sufficient oxygen permeability (oxygen barrier rate) or water permeability (moisture barrier rate) when coated with a thin film, and are solid at room temperature. In most cases, it is difficult to prepare a liquid composition because it exists as a high-molecular polymer. In particular, manufacturing with an eco-friendly aqueous coating solution is currently more difficult.

Recently, without using a synthetic resin as a material, some techniques have been disclosed in which a natural product having a property of decaying over a certain period of time after manufacturing a film is used as a material.

In particular, a lot of protein is used as such a natural product. In order to mold a natural product into a form such as a coating layer or a film, it must be a polymer in the form of a polymer, because the protein is a polymer material having relatively well these characteristics.

However, the protein coating solution prepared as an aqueous solution causes decay accompanied by a bad odor when 1 to 2 weeks have elapsed after production, and it is difficult to obtain a shelf life sufficient for commercial distribution, and a coating composition containing protein is used. In the process of distribution, the produced film for packaging material has problems such as significantly lowering the functionality of the film due to the occurrence of holes in the protein coating layer inside the film due to causes such as mold.

Accordingly, as the barrier properties of the film are lowered, the industrial value as a coating composition is inevitably lowered, such as the food contained in the food packaging material is exposed to oxygen and moisture and is quickly damaged.

Therefore, in the case of preparing a coating composition using protein as a main component, a solution to such decay and odor is also very important.

The most common natural product-based coating solution composition is prepared as an aqueous solution having a solid content of 20% by mixing protein and sorbitol in a 1:1 ratio by weight. The storage stability of this mixture composition is shown in FIGS. 3a, 3b, and 3c. In the case of the mixed solution, Figure 3a is a photograph immediately after preparing a 1:1 mixed aqueous solution of protein and sorbitol having a total solid content of 20%, and FIG. This is a photograph after, and FIG. 3c is a photograph 8 weeks after preparing a 1:1 mixed aqueous solution of protein and sorbitol having a total solid content of 20%.

As shown in Fig. 3a, when the protein is diluted in water, it is spread in the water in a slightly cloudy state at first, but as time goes on, it gradually changes to a porridge-like change with time. And, after 2 weeks elapsed after a certain period of time, as shown in FIG. 3b , the viscosity increased significantly and gelled, and the protein was solidified in the form of tofu. And, after the lapse of 8 weeks, as shown in FIG. 3c, it is decomposed.

The solidification phenomenon of the aqueous protein solution is that when powdery high molecular protein particles, which are a quaternary structure or a mixture of tertiary and quaternary structures, are dispersed in water, the protein particles become tertiary, and when they are hydrated, they are released into a secondary structure. This is a phenomenon in which the prepared liquid composition appears to have finally become a gel as it becomes a thick liquid with high viscosity, and a large number of strong hydrogen bonds occur between the loosened secondary structure of the high molecular protein.

When a coating composition containing a protein changes over time during storage or distribution and the viscosity increases rapidly, it is not easy to manufacture a film-type coating layer or a food packaging material using the coating composition itself, but the prepared coating layer It may not be uniformly formed and the film shape of the food packaging material may not be maintained in a good shape.

Since the protein itself does not have water resistance, the dried film layer formed of the protein polymer has weak water barrier properties compared to its excellent oxygen barrier ability. Therefore, when a food packaging film prepared with such a coating composition is in contact with moisture for a long period of time in a humid environment, there may be a problem that the protein layer present inside the film-type packaging material is denatured by moisture, and this is ultimately the Decreases blocking performance. When such a problem occurs in a functional barrier film used as a food packaging material, it is a direct cause of exposing oxygen or moisture to food, so there is a problem that the commercial property as a coating composition for controlling or blocking oxygen or moisture permeability disappears.

Accordingly, the present applicant uses an environment-friendly and harmless protein as the main ingredient, but minimizes the protein decay problem and the increase in viscosity to prepare a distribution composition for coating, and this coating composition is excellent for coated film packaging materials. By providing water resistance to maintain the unique properties of the food packaging film even in the unavoidable moisture contact environment that occurs during the distribution process of packaging materials, it is applied to a wider variety of items compared to the previous protein-containing composition and food packaging film manufactured using the same. A review was made on the development of a coating composition containing a protein with improved water resistance.

Domestic Registration Publication No. 10-1742708 Domestic Registration Publication No. 10-1820878

Natural product-based coating compositions for food packaging materials have problems of decay and odor generation, viscosity increase, and gelation of the composition occurring during storage and distribution. There is a problem of quality deterioration caused by poor water resistance of

The present invention improves the antiseptic and water resistance of a polymer protein, the first of which is a polymer, among the manufacturing components of a conventional oxygen-blocking natural coating agent that mixes a natural product-based high molecular protein polymer and a natural product-based hydrophilic plasticizer (filler) during the distribution period of the composition By preventing or alleviating decay, odor, viscosity increase and gelation, a sufficient shelf life is secured, and a packaging film is manufactured using this to improve the durability and water resistance of the manufactured film, and the second By replacing hydrophilic plasticizer (filler) with lipophilic filler, it maintains excellent oxygen barrier ability and is a packaging material that can be distributed for a long time without deterioration of barrier ability even when the dried coating film of the final packaging film is exposed to moisture during distribution and storage. An object of the present invention is to provide a coating composition comprising a protein with improved water resistance, which is a natural product-based eco-friendly material capable of producing , and a method for manufacturing the same.

The present invention provides hydrophilic amine groups distributed in a linear polymer protein molecule as a first solution in order to lower the hydrophilicity of the polymer protein and impart lipophilicity among the components of the coating composition consisting of a hydrophilic polymer protein and a hydrophilic plasticizer (filler). Block with oily acid. Substances that can be used for this purpose are collectively defined as "Hydrophobic Blocking agents".

As a second solution, cross-linking between protein molecules is induced, thereby reducing the size of pores formed inside the dry film compared to an untreated protein coating layer when forming a dry film, and improving the physical properties of the dry film. induce For this purpose, substances that can be used to induce crosslinking are collectively defined as "Cross linking agents".

As a third solution, the existing "plasticizer", which is an extremely hydrophilic material, is to be replaced with a relatively lipophilic material. In the present invention, the definition of the existing material is defined as "filler" rather than "plasticizer". More specifically, conventional plasticizers (fillers) are defined as “hydrophilic fillers” and fillers of the present invention having good water resistance are defined as “hydrophilic fillers”.

One aspect of the invention is a protein; and lipophilic monomolecular monoacid; Including, wherein the lipophilic monomolecular monoacid is bound to a secondary amine (-NH-) in a protein molecule through a covalent bond by a neutralization reaction, and as a result, hydrophilicity is reduced and water resistance is improved. A composition is provided.

According to a preferred feature of the present invention, the coating composition further comprises a crosslinking agent and a filler, and by neutralizing the lipophilic monomolecular mono-acid, the crosslinking agent and the filler with ammonia to improve compatibility with an aqueous protein solution and block reaction rate and the crosslinking reaction rate can be controlled.

According to a preferred feature of the present invention, the coating composition may include a repeating unit represented by the following formula (1).

<Formula 1>

In Formula 1, functional group 1 and functional group 3 are reaction sites in a protein molecule capable of binding to an acidic substance, respectively.

According to a preferred feature of the present invention, the lipophilic monomolecular monohydric acid as a blocking agent can block the protein using one of sorbic acid and benzoic acid.

According to a preferred feature of the present invention, a cross linker can be used to improve the physical durability of the dry coating film of the composition, and the cross-linking agent is zinc oxide solution, malic acid, citric acid. , maleic acid (Maleic Acid), maleic anhydride (Maleic Anhydride), one or more of phthalic acid (Phthalic acid) may be used in combination.

According to a preferred feature of the present invention, the lipophilic monomolecular monohydric acid or polyhydric acid can be mixed and neutralized in a molar ratio of 1:1 using ammonia water having a concentration of 28% so that the lipophilic monomolecular monohydric acid and polyhydric acid are neutralized. have.

According to a preferred feature of the present invention, the protein is whey protein isolate (WPI), whey protein concentrate (WPC), soy protein isolate (Isolated soy protein, ISP), rice protein (rice protein) isolate, RPI), oat protein isolate (OPI), pea protein isolate (PPI), corn protein (Corn zein), may include any one or more selected from the group consisting of.

According to a preferred feature of the present invention, the lipophilic monomolecular monohydric acid is sorbic acid, and the protein content in the composition comprises 5 to 15 parts by weight based on 100 parts by weight of the coating composition, and the sorbic acid is It may be included in a ratio of 10 to 30 parts by weight based on 100 parts by weight of the solid content of the protein contained in the coating composition.

According to a preferred feature of the present invention, as a crosslinking agent, zinc oxide may be further included, wherein the zinc dioxide is 10 to 20 parts by weight based on 100 parts by weight of the solid content of the protein contained in the coating composition. may be included.

According to a preferred feature of the present invention, the coating composition further comprises a lipophilic filler, and the filler is a lipophilic material, at least one or more of aliphatic monohydric acids such as oleic acid and octanoic acid and aliphatic monohydric alcohols such as cetyl alcohol. can

까지 1시간 30분 동안 승온한 후 90

에서 2시간 이상 교반하여 11% 단백질 수용액을 마련하는 제2 단계; 상기 11% 단백질 수용액을 60

까지 냉각하는 제3 단계; 상기 11% 단백질 수용액에 상기 30% 소르빈산 암모니아 수용액을 투입하여 제1 혼합물을 마련하고, 상기 제1 혼합물을 45

내지 60

를 유지한 채 4시간 이상 교반하여 소르빈산이 단백질의 2차 아민과 화학 결합되어 단백질의 관능기를 블록하는 제4 단계; 상기 제1 혼합물에 12% 이산화아연 용액을 투입하고 45 내지 60

에서 6시간 이상 더 교반하여 단백질을 가교하여 제2 혼합물을 마련하는 제5 단계; 상기 제2 혼합물을 상온으로 냉각하는 제6 단계; 상기 제2 혼합물을 필터링하는 제7 단계; 및 상기 제2 혼합물에 충진제를 투입하는 제8 단계; 를 포함하는 내수성이 개선된 단백질을 포함하는 코팅용 조성물의 제조 방법을 제공한다.Another aspect of the present invention, the first step of preparing a 30% sorbic acid-ammonia aqueous solution by adding sorbic acid and ammonia aqueous solution to water; Mix water and protein in a ratio of 8:1 and

After heating for 1 hour and 30 minutes until 90

a second step of preparing an 11% aqueous protein solution by stirring for 2 hours or more; 60 of the 11% protein aqueous solution

a third step of cooling to A first mixture was prepared by adding the 30% aqueous ammonia sorbate solution to the 11% protein aqueous solution, and the first mixture was 45

to 60

a fourth step of blocking the functional group of the protein by chemically bonding the sorbic acid with the secondary amine of the protein by stirring for at least 4 hours; A 12% zinc dioxide solution was added to the first mixture, and 45 to 60

a fifth step of preparing a second mixture by cross-linking the protein by further stirring at a temperature of 6 hours or more; a sixth step of cooling the second mixture to room temperature; a seventh step of filtering the second mixture; and an eighth step of adding a filler to the second mixture; It provides a method for producing a composition for coating comprising a protein with improved water resistance comprising a.

According to an embodiment of the present invention, in the production and distribution of a high molecular protein aqueous solution capable of reducing the amount of microplastics generated by replacing synthetic resins and producing a more eco-friendly coating agent, changes in the composition over time, spoilage and By effectively preventing the odor problem and improving the water resistance of protein solids in the dry coating, which is a weakness of the existing prior art, it is possible to manufacture a stable protein composition in various distribution environments, thereby satisfying the requirements of more diverse applications. suggest possible directions.

In particular, by remarkably improving the performance degradation of the film due to high humidity during long-term storage of the film, which was a problem due to the weak water resistance of the protein layer in the production of a functional film for blocking oxygen and moisture, a natural product that is currently being tried in a limited way It is possible to expand the scope of the manufacturing industry of the composition for the base coating.

In addition, the composition for coating comprising a protein with improved water resistance prepared by the present invention can significantly improve water resistance compared to the filler mentioned in the prior art, and the coating film coated with the protein with increased crosslinking density has internal pores Since the size of the particle is reduced and the pores are reduced, the content of the required filler can be reduced, and the side effects caused by excessive use of the filler with weak water resistance can be reduced.

1 is a cross-sectional view showing the structure of a conventional food packaging film.
2 is a flowchart schematically illustrating a method for improving water resistance of an aqueous protein solution according to an embodiment of the present invention.
Figures 3a to 3c are photographs showing the change over time and the decay phenomenon of the conventional protein / sorbitol aqueous solution.
4A is a photograph showing the precipitation phenomenon occurring in the protein aqueous solution due to shock when the lipophilic acidic material is directly injected into the protein aqueous solution without neutralizing it.
4B is a photograph of a stable aqueous protein solution obtained when shock is prevented by adding the lipophilic acidic substance to the aqueous protein solution after neutralization.
Figures 5a to 13b are photographs each showing the decay occurrence time of the coating composition according to the present invention and the conventional coating composition.
14 shows that when a hydrophobic material as a filler is used in excess relative to the solid content of the protein, incompatibility with an aqueous protein solution increases, and when a coating film is formed by coating such a composition, the excess filler is micro-seeding, gloss loss, whitening phenomenon It is a photograph showing that it causes side effects such as.

Hereinafter, preferred embodiments of the present invention will be described. However, embodiments of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below.

In addition, 'including' a certain component throughout the specification means that other components may be further included, rather than excluding other components, unless otherwise stated.

composition for coating

The present invention starts with an analysis of the cause for preventing thickening and gelation of a composition due to a hydration reaction of a protein that occurs during storage after preparation of an aqueous polymer protein solution.

The composition for coating according to an embodiment of the present invention uses a naturally-derived polymer protein as a binder, and includes a lipophilic monomolecular mono-acid for the block of an amine group, which is a functional group in the protein molecule. The lipophilic monomolecular monohydric acid is chemically bonded to a secondary amine (-NH-) present in the polymer protein by a covalent bond by a neutralization reaction, and blocks the hydrophilic amine group, which causes the weak water resistance of the protein polymer. It lowers the hydrophilicity of the protein and prevents protein decay. The lipophilic monomolecular monoacid will be described in more detail below. In addition, the coating composition may further include at least one of monomolecular diacids such as zinc oxide solution or maleic anhydride as a crosslinking agent in order to increase the crosslinking density of the protein.

Proteins have a carboxyl group (-COOH) and an amine group (-NH ₂ ) at the ends of molecular chains, respectively, and amino acids as shown in Chemical Formulas 2 and 3 in the middle of the molecular chain have a plurality of peptide bonds , -CO-NH-) as a compound in the form of a polymer, in which a ketone and a secondary amine are continuously present in the middle of the chain.

<Formula 2> amino acid

<Formula 3> peptide bond structure of amino acids.

As shown in the following Chemical Formula 4, among the components of the coating composition, a polymer protein is a backbone for forming a dry film and can be viewed as a binder having a linear structure such as a fiber. General linear polymers (e.g. PET, acrylic, PE, etc.) realize sufficient oxygen permeation blocking rate when the polymer is prepared in liquid form, coated and dried, and when the dry film thickness is a thin film (DFT 1㎛ ~ 5㎛) hard to do It is difficult to realize an excellent blocking rate against oxygen and moisture in a coating solution composition prepared solely from a high molecular protein, similar to a general linear polymer. The oxygen permeation blocking ability is completed by filling the pores created between the protein molecules with a sufficient amount of filler when the linear polymer proteins overlap each other and dry into a fibrous structure.

<Formula 4>

High molecular weight proteins include whey protein isolate (9410 WPI), whey protein concentrate (8000 WPC), isolated soy protein (ISP), rice protein isolate (RPI), oat protein isolate (OPI), It may include any one or more selected from the group consisting of pea protein isolate (PPI), corn protein (Corn zein), wheat protein (Gluten), and the present invention is not limited thereto.

In this embodiment, isolated soy protein (ISP, purity 99%) is used for the protein in consideration of commercial competitiveness in terms of price and smoothness of material supply, and the protein content is protein per 100 parts by weight of the coating composition The solid content may be 5 to 15 parts by weight.

The industry generally suggests a coating composition having a protein content of 10 g in 100 g of the final coating solution composition, but even a composition with this content does not sufficiently prevent an increase in the viscosity of the coating composition due to changes over time during storage, and eventually distribution is difficult. It is considered an impossible product. Therefore, the content of protein mentioned in the prior art cannot be given a technical meaning, and it is only correct to judge it as a target content for manufacturing a commercial product.

As shown in Formula 5 below, there are four types of hydrophilic groups in the polymer protein molecule, all of which induce strong hydrogen bonds to induce thickening and gelation of aqueous solutions (jelly, jelly, etc.) is understood

<Formula 5> Structure of a functional group in a protein molecule.

In this embodiment, by blocking the lipophilic and non-polar monomolecular acidic substance with an amine-based hydrophilic group inside the protein, the hydrophilicity of the polymer protein is weakened and the lipophilicity is strengthened to increase the water resistance of the protein molecule, and between the hydrophilic functional groups of the protein molecule. It is intended to prevent the thickening phenomenon that occurs during storage of the protein aqueous solution by blocking the hydrogen bonding that occurs in

Among the functional groups capable of inducing hydrogen bonding in a protein molecule, one functional group 1 and one functional group 4 exist at the end of one protein molecule, and n functional groups 2 and 3 exist in proportion to the molecular weight of each protein. Therefore, it can be estimated that the main cause of thickening or gelation is mainly caused by functional groups 2 and 3 rather than functional groups 1 and 4. Of these, the ketone group corresponding to 2 may hydrate with water to induce an enolketol reaction, but it is not easy to block the second functional group with a lipophilic (or non-polar) material because of its low reactivity.

Domestic registration publication No. 10-1742708 and domestic registration publication No. 10-1820878, which exist as domestic prior art, induce a reaction with the second functional group (ketone group) of the protein by injecting a primary amine into an aqueous protein solution, and through this By generating an oxime monomer in a protein molecule, it prevents decay and alleviates changes over time. This is a technology clearly different from the method of implementing the improvement of water resistance, prevention of aging, and prevention of decay by blocking the third functional group proposed by the present invention.

The present invention blocks highly reactive functional group 3 (secondary amine) with a lipophilic (non-polar) acidic monomolecular substance to impart lipophilicity to protein molecules to enhance water resistance, and also hydrogen generated in aqueous protein solution through this An object of the present invention is to prepare an aqueous protein solution in which the viscosity of the composition is stably maintained during the distribution process by preventing or alleviating the thickening caused by hydrogen bonding that occurs during storage of the aqueous protein solution by reducing binding.

Monomolecular acidic substances include acetic acid, formic acid, and many other low molecular weight aliphatic acids, all of which can impart similar functions. However, the hydrophilic monomolecular acidic substance soluble in water has the effect of lowering the viscosity, but the effect of improving the water resistance is insignificant.

As a first means to achieve the purpose of reducing viscosity, preventing thickening, and improving water resistance, a protein aqueous solution is prepared by blocking proteins with various low molecular weight monoacids, and then coated and cured to prepare a film, heat resistance and drying of the dried coating film Sorbic acid ((mp 135 ℃, bp 228 ℃) was selected as the most suitable monomolecular acidic material through comparative experiments on film strength, water resistance, and antiseptic properties. The sorbic acid is a relatively safe material widely used as a preservative for edible beverages, In order to prepare an aqueous solution, it is mainly prepared as a neutralized product in the form of sodium sorbate to prepare an aqueous solution.

And, as a substance similar to the sorbic acid, there are benzoic acid (mp 122 ℃, bp 250 ℃), propionic acid (mp -20.5 ℃, bp 141.15 ℃), etc., as a natural material, octanoic acid (mp -16.7 ℃, bp 239.7 ℃) ), but it was inferior to sorbic acid ((mp 135℃, bp 228℃) in water resistance, heat resistance of dry coating, and scratch resistance.

이하)와 일시적인 친수성을 부여하기 위한 수단으로 저분자 산성물질에 블록할 중화제는 비점이 낮은 저분자의 중화제가 바람직할 것이다. 예를들면 비점이 37.7℃인 농도 28%의 암모니아수를 이용하여 소르빈산을 중화하고 수용액으로 제조하여 사용할 수 있다.일 실시 예에 따르면, 본 실시 예의 코팅용 조성물에서 단백질 고형분 100중량부에 대한 소르빈산 고형분의 함량 범위는 10 내지 30중량부가 적당하다. 상기 소르빈산은 단백질의 아민기에 대하여 블록을 유도하여 단백질의 친수성과 수소결합을 감소시키는 기능을 구현할 수 있는 1가산의 단분자 물질이다. When the monomolecular monoacid is directly mixed with a high molecular protein having a large amount of amine groups, flocculation, seeding, and precipitation of the protein occur due to strong reactivity. In order to prevent this, sorbic acid neutralized with sodium can be used, but in this case, the binding force between sorbic acid and sodium ions is very strong, so it is difficult for sodium ions to be separated from sorbic acid, and as a result, it becomes difficult for sorbic acid to block the amine group of the protein. In addition, sodium does not evaporate and remains in the dry coating film, thereby reducing the water resistance of the produced film. In order to solve this disadvantage, it is preferable to neutralize sorbic acid with a neutralizing agent having an appropriate dissociation temperature rather than a metal ion such as sodium. At this time, the heat hydration process temperature of the protein (100

As a means for imparting temporary hydrophilicity with the following), a neutralizing agent with a low boiling point to block the low molecular weight acidic substance will be preferable. For example, sorbic acid may be neutralized using ammonia water having a concentration of 28% with a boiling point of 37.7° C. and prepared as an aqueous solution. According to one embodiment, the sorbic acid solid content with respect to 100 parts by weight of the protein solid content in the coating composition of this embodiment. The content range is suitable from 10 to 30 parts by weight. The sorbic acid is a mono-acid monomolecular substance capable of implementing a function of reducing the hydrophilicity and hydrogen bonding of a protein by inducing a block with respect to the amine group of the protein.

Since high molecular weight protein and sorbic acid are quickly and strongly bound by neutralization reaction, sorbic acid can easily block the amine functional groups (functional groups 1 and 3) of the protein. Specifically, by the neutralization reaction, sorbic acid may induce a block of amine-based functional groups (H2N-, -NH-), which are the first or third functional groups present in the protein molecule.

At this time, the main action mechanism and effect of the coating composition is to block the sorbic acid (Sorbic acid) in the secondary amine group (-NH-) of the protein which accounts for the majority by a neutralization reaction, thereby preventing the thickening phenomenon by interfering with the hydrogen bonding of the 3rd functional group. and finally, a low-viscosity aqueous solution can be obtained. In addition, as an additional effect, when the solid content of the protein is 10 parts by weight based on 100 parts by weight of the total composition, when 1 part by weight or more of the sorbic acid is added, the sorbic acid acts as a preservative in the aqueous protein solution, showing excellent anti-corruption and odor prevention effects. was confirmed through the present invention. This mixing ratio means that the minimum mixing amount of the sorbic acid solid content is 10 parts by weight or more with respect to 100 parts by weight of the protein solid content.

At this time, when sorbic acid is used alone with respect to 100 parts by weight of protein, if the content of sorbic acid is used too low, less than 10 parts by weight, it is difficult to expect a sufficient decrease in viscosity, and the anti-corruption effect of the aqueous protein solution is also not sufficiently implemented. Conversely, if the content of sorbic acid as a solid content exceeds 50 parts by weight based on 100 parts by weight of the protein solid content, the viscosity lowering effect and the anti-corruption effect are excellently realized, but the hydrophilicity of the protein polymer rapidly decreases, resulting in the precipitation of the polymer protein in the aqueous solution. , If the composition on which the protein is deposited is coated and dried, seeding occurs on the surface of the dried coating film and the side effect of reduced gloss occurs.

When sorbic acid and zinc dioxide are mixed with respect to 100 parts by weight of protein solid content, the hydrophilicity of the protein is further reduced as the protein is crosslinked by zinc dioxide, so the seeding and gloss reduction in aqueous solution are further reduced due to the increase in the lipophilicity of the protein. increase Therefore, when zinc dioxide, which is a crosslinking agent, is mixed with sorbic acid, the amount of sorbic acid used should be reduced within an appropriate range in order to achieve a desirable dry coating film.

In the present invention, a mixture of sorbic acid and zinc dioxide was used, and the content of sorbic acid was determined to be 30 parts by weight as solid content with respect to 100 parts by weight of protein solid content. In this case, the appropriate mixing amount of zinc dioxide was limited to 10 to 20 parts by weight based on the solid content.

When the content of zinc dioxide is fixed to 20 parts by weight with respect to 100 parts by weight of protein and sorbic acid is mixed, when the sorbic acid is used in excess of 30 parts by weight or more, the viscosity lowering effect and the anti-corruption effect are more excellently realized, but the protein The hydrophilicity of the polymer decreases more rapidly, so that the polymer protein may precipitate in an aqueous solution and precipitate may occur. This happens again.

Therefore, when mixed with zinc dioxide, it exhibits sufficient viscosity lowering effect and anti-thickening ability, and the amount of sorbic acid used, which does not show precipitation or seeding, is 10 to 30 parts by weight as solid content based on 100 parts by weight of protein solids based on soybean protein. have.

The chemical bond between the protein and sorbic acid can be viewed as a covalent bond through a neutralization reaction, and it is clearly distinguished from the case where an anti-corruption material is added to the coating composition as an additive to not chemically react with the protein and is simply mixed. In addition, by applying the present invention, various monovalent acids can be used to block proteins and block hydrogen bonds to prevent or alleviate the increase in the viscosity of the aqueous protein solution, but all monovalent acids do not exhibit anti-corruption effects.

In this embodiment, the most preferable lipophilic monomolecular monoacid may be defined as sorbic acid. The sorbic acid is a food additive and has very low toxicity to the human body and is a material used as a food preservative in general edible beverages and the like. As a material of similar lipophilic aliphatic monoacid, benzoic acid, octanoic acid, etc. can be substituted for sorbic acid. However, the antiseptic effect is not sufficiently realized compared to that of sorbic acid.

Hereinafter, the present embodiment will be described as using sorbic acid as the lipophilic monomolecular monoacid.

The composition for coating of this embodiment may include a repeating unit represented by the following formula (1).

<Formula 1>

In Formula 1, functional group 1 is a primary amine, functional group 2 is a ketone group, functional group 3 is a secondary amine, and functional group 4 is a carboxylic acid group. And, among them, functional group 1 and functional group 3 become binding (reaction) sites in the protein molecule capable of binding to acidic substances, respectively.

In addition, protein polymers can be crosslinked to improve physical properties such as adhesion, abrasion resistance, scratch resistance, and hardness as well as chemical properties such as water resistance and decay of the coating film. Zinc dioxide was selected as an internal crosslinking agent for aqueous protein solutions. A dry film with a three-dimensional network structure formed by crosslinking is formed more rigidly than a dry film formed by simple physical entanglement of a protein polymer, a linear polymer, and through this, the physical and chemical properties of the dry film can be improved. .

By using a low molecular polyacid as an internal crosslinking agent, a neutralization reaction can be induced in the 3rd functional group at various positions on the protein polymer line, and thus, internal crosslinking of the protein polymer aqueous solution can be attempted. Low molecular weight polyacids include various types of industrial organic acids (maleic acid, phthalic acid, adipic acid, etc.) and naturally derived polyacids (malic acid, citric acid, etc.).

Among them, maleic anhydride, malic acid, and citric acid, which can be prepared in aqueous solution without a neutralizer, can be considered as crosslinking agents of the present invention. OH) containing malic acid and citric acid has a crosslinking effect such as durability improvement, but has no anti-corruption effect, but rather increases the viscosity of the composition and the improvement effect on water resistance is very insignificant.

The following Chemical Formula 6 is the hydroxyl group structure of malic acid, and the following Chemical Formula 7 is the hydroxyl group structure of Citric Acid.

<Formula 6> Malic Acid

<Formula 7> Citric Acid

On the other hand, maleic anhydride has an effect of inhibiting the increase in viscosity, and the abrasion resistance and water resistance of the dry protein film are also improved. However, maleic anhydride is difficult to classify as a natural product-based material, and the effect of improving water resistance and water repellency is weak compared to the case of using zinc dioxide. Formula 8 below shows the structure of maleic anhydride.

<Formula 8> Maleic anhydride

When lipophilic mono-molecule mono-acid blocking agent or poly-acid, which is a crosslinking agent, is directly added to an aqueous protein solution, it is not miscible with water due to the lipophilicity of the mono-molecule mono acid or cross-linking agent, and shock due to incompatibility with the protein solution is generated. Protein aqueous solution may precipitate or precipitate may occur. And hydrophilicity is given to the polyacid, which is a crosslinking agent, to prevent the problem of precipitation or precipitation of the protein aqueous solution of this embodiment.

As another type of internal crosslinking agent, polyvalent metal salts can be considered. For example, hydrolyzate of TEOS (Tetra ethoxy ortho silicate), a derivative of silicic acid, hydrolyzate of other functional silanes such as aminosilane and epoxy silane, aqueous boric acid solution, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, titanium dioxide, etc. have.

Among them, silicic acids and titanium dioxide have poor storage properties and compatibility, which causes shock and forms a strong precipitate. Also, if the amount of silicic acids and titanium dioxide is increased enough to express water resistance when used alone, the hardening reaction with the aqueous protein solution proceeds rather than There is a problem in that the long-term storage properties of the aqueous protein solution are very poor.

In addition, boric acid and polyvalent alkali metals are hydrophilic materials, and polyvalent metal materials of this series exhibit anti-corruption and viscosity lowering effects, but have a disadvantage in that water resistance is weakened.

For this reason, in the present invention, a zinc dioxide solution was selected and used as an internal crosslinking agent excellent in compatibility, storage properties, and water resistance. The dosage of zinc dioxide solution must be determined through experimentation. When used in excess, due to the water repellency (hydrophobicity, lipophilicity) of zinc dioxide, it causes micro-seeding by aggregating proteins in the aqueous solution, and Reduces gloss and causes haze.

However, when an appropriate content is used, it increases the water repellency of the dried coating film as well as the excellent water resistance improvement effect. By mixing zinc dioxide, which functions as a water repellent and an internal crosslinking agent, together with sorbic acid, which has an antiseptic effect and a viscosity lowering effect, viscosity stability and antiseptic properties of the aqueous solution were obtained. It can exhibit very good synergy in

<Formula 9> Schematic diagram of the internal cross-linking reaction between high molecular weight protein and zinc dioxide.

Formula 9 shows the crosslinking reaction of zinc dioxide, and in the zinc dioxide solution, zinc dioxide acts as a cross-linker for protein molecules, thereby increasing the molecular weight of the protein and making the hydrophilic portion relatively hydrophobic. When the molecular weight of the protein increases and the hydrophilic portion becomes hydrophobic, the water resistance of the coating composition is improved. In addition, in the case of forming a dry film by coating the composition prepared in this way, the film structure is more densely formed than the conventional composition, thereby improving the water resistance of the dry film as well as mechanical properties (eg, scratch resistance, abrasion resistance, adhesion). It is possible to implement a coating film.

Chemical formula 10 illustrates the structure of a polymer protein with improved water resistance by blocking with sorbic acid and crosslinking with zinc dioxide.

<Formula 10> Example of the mechanism of action of proteins, sorbic acid (blocking agent), and zinc dioxide (crosslinking agent).

When the three-dimensional network structure of the dry coating film is formed more densely, the size of the micropores present inside the coating film is reduced, which gives a very positive synergistic effect in realizing excellent oxygen barrier properties and moisture barrier properties. Zinc dioxide acts as a strong water repellent and prevents moisture exposed on the surface of the dry film from penetrating into the dry film, so it is possible to minimize the performance degradation of the packaging material due to humidity, and in conclusion, it can improve the distribution stability of the manufactured packaging material. can be further improved.

In the present invention, an aqueous solution of 12% concentration of zinc dioxide was used, not powder. It is a composition often called a zinc-ammonium-carbonate (molar ratio 1:2:2) solution and is partially used as a crosslinking agent for water-based polymers. It is mainly known as a crosslinking agent that reacts with the carboxyl group present at the terminal of the water-based acrylic polymer, but its effect is insignificant and therefore has little industrial use. The aqueous solution may be, for example, a product of BASF (product name: ZINC OXID SOLUTION #1, BASF), but the present invention is not limited thereto. The reason why BASF's zinc dioxide aqueous solution was used is because this product is commercially mass-produced and has a reasonable price and easy procurement and handling compared to direct production of zinc dioxide aqueous solution.

In the present invention, through a long-term study, it was confirmed that the aqueous zinc dioxide solution is suitable for proteins and is a very good crosslinking agent with various advantages.

And, in this embodiment, distilled water or purified water and tap water may be used as the solvent of the coating composition.

On the other hand, the composition for coating according to the present invention may further include a filler. In order to improve the oxygen and moisture barrier properties and provide barrier properties to the dry coating film, it is necessary to physically fill numerous micropores existing in the three-dimensional network structure of the dry coating film formed of proteins by mixing an appropriate amount of filler.

In the existing industry, this is conventionally referred to as "elastomer", but in the present invention, it is defined as "fillers" to explain the functional role of the material used.

When the aqueous protein solution composition blocked with sorbic acid of this embodiment and crosslinked with zinc dioxide is coated on the base film and the drying process is performed, a physical drying process is performed according to the evaporation of moisture to form a three-dimensional network structure, Forms a coating film with good water resistance. The barrier property to oxygen is that the liquid filler mixed with protein properly penetrates into the numerous pores formed inside the protein film, which is formed like a fiber, and then keeps the pores filled, and then in the cooling process. By drying to a smooth surface, the properties required for the film are expressed.

To this end, in general, the coating composition including the filler should be heat-dried at a temperature higher than the melting point of the filler during the drying process after the coating operation, and an appropriate time for the filler to penetrate sufficiently is required. Thereafter, the film is cooled to room temperature to complete film production.

In summary, the oxygen and moisture permeation prevention ability of the coating composition is not realized by the protein, which is the binder, but depends on the mixed filler, so an appropriate kind of filler must be selected, an appropriate amount must be added, And it requires sufficient temperature and time in the drying process.

A typical filler among naturally-derived natural products is sorbitol (Sorbitol, m.p: about 95 ° C., aliphatic polyhydric alcohol) obtained from glucose, and the appropriate drying process temperature of the coating solution composition using sorbitol is about 100 ° C. or higher. In addition, an appropriate mixing ratio is to use a protein and a filler in a ratio of 1:1 (a ratio of 100 parts by weight of sorbitol to 100 parts by weight of protein) by weight of the solid content.

In previous studies, aliphatic polyhydric alcohols such as sorbitol were mainly studied as preferred fillers, but according to the results obtained through the present invention, additionally, aliphatic monohydric alcohols such as cetyl alcohol, aliphatic monohydric acids such as oleic acid, and polyacids such as malic acid and citric acid They can also be used sufficiently as fillers.

The aliphatic polyhydric alcohol is, for example, fructose, sucrose, mannitol, propylene glycol, glycerol, and polyethylene glycol (Polyethylene glycol, PEG200, PEG400, PEG600, etc.) etc.

The aliphatic monohydric alcohols include, for example, cetyl alcohol, lauryl alcohol, which is solid at room temperature and insoluble in water.

The aliphatic monoacid includes, for example, oleic acid, cetylic acid, and lauryl acid. In addition, natural substances with a small molecular weight compared to protein include casein, gelatin, wheat protein, Gluten, chitosan, dextrins, pectin, carrageenans, and the like. .

And, as the polyacid, for example, there are hydrophilic natural substances such as malic acid and citric acid.

In the present invention, any one or more selected from these groups may be used as the filler, and the present invention is not limited thereto. However, since the aliphatic polyhydric alcohol-based filler has excellent oxygen barrier properties but is very vulnerable to moisture, it does not meet the goal to be solved in the present invention. In this embodiment, preferably, a fatty acid monoacid-based filler may be used, for example, oleic acid may be preferably used as a filler.

According to the contents of the prior art, in general, the filler may include 50 to 150 parts by weight of solid content based on 100 parts by weight of natural protein solids that are not artificially denatured, and preferably 95 to 105 parts by weight is recommended.

However, in the present invention, the protein was appropriately modified using sorbic acid and zinc dioxide, and the content of the lipophilic filler is 30 parts by weight of the pure protein solid content excluding the solid content of sorbic acid and zinc dioxide in the aqueous protein solution with improved water resistance. To 70 parts by weight can be used, preferably 45 to 55 parts by weight is recommended. When this range is satisfied, there is a more advantageous effect in terms of suppressing the appearance defect of the coating layer due to an excessive amount of the filler and implementing excellent oxygen barrier properties.

If the content of the lipophilic filler is less than 30 parts by weight, the pores of the dry coating film are not sufficiently filled, and thus a problem of increasing oxygen permeability may occur. In addition, due to insufficient adhesion between the base film and the dried protein layer, a problem of peeling between the coating layer and the base film may occur.

And, when the content of the filler exceeds 70 parts by weight, the gloss and transparency of the dried coating film may decrease in the process of drying the composition after coating, and the dried coating film or the prepared packaging material is exposed to moisture for a long time in a high temperature and high humidity environment. When stored in the state of being, the surface may be whitened or haze may occur due to incompatibility with moisture penetrating into the fine pores existing on the surface of the dried coating film, which may cause poor appearance.

As a lipophilic aliphatic monoacid, a water-insoluble filler, it is a method to inject oleic acid into an aqueous protein solution without shock. It is preferable to use In this case, the oleic acid aqueous solution is prepared as a high-viscosity milky creamy paste.

The present invention is a technology for improving the water resistance of natural polymeric protein used as a binder among components of a natural product-based coating agent being studied for oxygen permeability control in food packaging materials.

Protein-based coatings for controlling oxygen permeability are often composed of high molecular weight natural proteins and low molecular weight hydrophilic fillers. While this type of mixture exhibits excellent oxygen permeation barrier properties, changes over time due to viscosity increase during storage of the coating solution and decay And the problem of odor generation due to decay occurs, and the dry coating film has excellent oxygen permeation barrier properties, but water resistance is very weak, so it is difficult to realize water barrier properties. has the disadvantage of not being easy to distribute.

Since most of the ingredients in food are organic, the barrier properties for both oxygen and moisture are important for the coating film used to seal and store food or organic substances. The composition for coating of this embodiment, including protein, sorbic acid and zinc oxide solution, implemented excellent water resistance, water repellency, and mechanical properties when forming a coating layer, and blocking oxygen among barrier properties By substituting an aliphatic polyhydric alcohol-based filler (eg, sorbitol) with excellent water resistance (eg, oleic acid) for excellent water-resistance but very vulnerable to moisture, a composition excellent in oxygen barrier properties and moisture barrier properties was prepared. Through this, it is possible to greatly improve the storability of food or organic matter.

In addition, since the coating composition can be prepared as a solution with a low viscosity while maintaining a sufficient concentration by denaturing the protein using sorbic acid and zinc dioxide, etc., it provides a composition with a good shelf life and stable workability during the coating process. A composition for coating can be provided.

In addition, the packaging material to which the coating composition of this embodiment is applied does not thermally decompose or evaporate the functional group for preventing spoilage in the dry coating film, so the storage or distribution period of the packaging material made of the film can be improved, and It can reduce problems such as loss of packaging materials or secondary contamination of packaged food or organic matter.

Method for preparing a composition for coating

Hereinafter, examples of a method for preparing a coating composition comprising a protein having improved water resistance of the present invention will be described as follows.

In order to prepare the coating composition of this embodiment, as a semi-finished product, a protein aqueous solution having a solid content of 11%, a sorbic acid-ammonia aqueous solution having a solid content of 30%, a zinc dioxide-ammonia-bicarbonate aqueous solution having a solid content of 12%, and oleic acid having a solid content of 20% - Prepare each of the ammonia aqueous solution pastes. An aqueous solution of sorbic acid-ammonia with a solid content of 30% acts as a blocking agent for the amine groups of the protein, and an aqueous solution of zinc dioxide-ammonia-bicarbonate with a solid content of 12% serves as a protein crosslinking agent, and an oleic acid-ammonia solution paste with a solid content of 20% acts as a filler to fill the pores created in the dry film.

Here, the first reason for preparing each substance as an aqueous ammonia solution and adding it to the aqueous protein solution is that each substance is a substance that does not dissolve in water. When sorbic acid and zinc dioxide, which are solids, are added directly to an aqueous solution at room temperature, they do not dissolve in water and exist as solid precipitates. At room temperature, liquid oleic acid is also insoluble in water, so it exists as an emulsion suspension when strongly stirred. When lipophilic (non-hydrophilic) substances present in the form of fine solid particles or emulsions exist in aqueous solution, only the protein molecules that come into contact with the particle surface in a state where the particle surface area is very small, the neutralization reaction occurs, and some proteins do not react at all. do.

At this time, as shown in FIG. 4A , when a lipophilic acidic substance reacts excessively with a specific protein molecule, the protein molecule abruptly loses its hydrophilicity and precipitates. In addition, the protein that did not get a chance to react does not have the effect of improving water resistance and lowering the viscosity. That is, as shown in FIG. 4B , in order to induce a uniform neutralization reaction for all protein molecules, the lipophilic acidic material is neutralized and converted into a hydrophilic material, and then it is added to the protein aqueous solution to spread it evenly inside the protein aqueous solution. For this purpose, it is preferable to use sorbic acid, zinc dioxide, and oleic acid to prepare an aqueous ammonia solution, respectively.

The second reason is to properly control the reactivity (rate) of the amine group of the polymer protein and the monomolecular acid substance. In general, the neutralization reaction occurs immediately at room temperature and the reaction rate is very fast.

However, when a monomolecular acid is neutralized with an organic amine and added to an aqueous protein solution, the amines located in the protein molecule (specifically, functional groups 1 and 3) are neutralized in advance, and the neutralizing agent bound to the acid group of the lipophilic monomolecular molecule may be thermally decomposed or dissociated. It cannot react with the monomolecular acid until it reacts with the acidic group of the lipophilic monomolecular molecule exposed as thermal decomposition of the neutralizing agent proceeds in the heating process. Therefore, the effect of reacting the lipophilic acid with the protein polymer as evenly as possible can be expected.

In this example, sorbic acid, zinc dioxide, and oleic acid were prepared and used as aqueous ammonia solutions, respectively, to prevent shock in the acidic material input process and induce an even neutralization reaction in the high molecular protein aqueous solution so that the block and crosslinking proceeded as uniformly as possible. compositions can be prepared.

On the other hand, neutralizing agents that can be used to prepare an aqueous solution of a lipophilic monomolecular acidic substance may be a primary amine, a secondary amine, a tertiary amine, or any combination thereof other than aqueous ammonia.

For example, the primary amine is methylamine, methanolamine, ethylamine, ethanolamine, propylamine, 3-amino-1-propanol (3-amino -1-propanol), isopropylamine, monoisopropanolamine, tert-butylamine, butylamine, hexylamine, dodecylamine ), cyclohexylamine, ethylenediamine, or hexamethylenediamine, but is not limited thereto.

The secondary amine is dimethylamine, diethylamine, diethanolamine, dipropylamine, N-ethylmethylamine, N-methylpropylamine (N -methylpropylamine), 3-(methylamino)-propanol [3-(methylamino)-propanol], N-isopropylmethylamine (N-isopropylmethylamine), dibutylamine, di-sec-butylamine (di- sec-butylamine), dioctylamine, N-methylcyclohexylamine, pyrrolidine, pyridine, or diethylenetriamine may be, but not limited to, does not

The tertiary amine is trimethylamine, trimethanolamine, triethylamine, triethanolamine, dimethylethanolamine, N,N-dimethylpropylamine, N ,N-dimethylbutylamine, 3-dimethylamino-1-propanol, N,N-dimethyldodecylamine, N,N-dimethylocta Decylamine (N,Ndimethyloctadecylamine), tripentylamine, N,N-dimethylcyclohexylamine (N,Ndimethylcyclohexylamine), 3-(dimethylamino)benzyl alcohol [3-(dimethylamino)benzyl alcohol] or N,N ,N',N'-tetramethyl-1,4-butanediamine (N,N,N',N'-tetramethyl-1,4-butanediamine), but is not limited thereto.

The neutralizing agent may be appropriately selected and used according to variables such as heating temperature and reaction time applicable to the manufacturing process.

In order to prepare the composition for coating of this embodiment, an aqueous solution of sorbic acid is prepared in a first step (S10). In this embodiment, the sorbic acid aqueous solution may be 30% sorbic acid-ammonia aqueous solution.

The 30% sorbic acid-ammonia aqueous solution may be prepared by mixing 25 to 35 parts by weight of sorbic acid, 30 to 40 parts by weight of water, and 25 to 35 parts by weight of an aqueous ammonia solution (NHOH) per 100 parts by weight of sorbic acid-ammonia aqueous solution. As the aqueous ammonia solution, an aqueous ammonia solution having a concentration of 25 to 35% may be used depending on the product being distributed. Ammonia water with a concentration of 28% is the most common product.

In this embodiment, as a unit by weight, 30% sorbic acid-ammonia aqueous solution may be prepared by mixing 36.5 g of water and 33.5 g of 28% aqueous ammonia solution (NHOH) with 30 g of sorbic acid. The 30% sorbic acid-amine aqueous solution, which is an amine-neutralizing acidic substance aqueous solution prepared as an intermediate, should be dissociated at a desired rate in a manufacturing environment of less than 100°C. If an aqueous solution is prepared by neutralizing a lipophilic monomolecular acid substance with an amine having a too high evaporation point (boiling point), the dissociation rate of the amine blocked in the acid monomolecules is very slow in the production process maintained at less than 100°C. As a result, the neutralization reaction that blocks the amine group of the protein does not occur or the productivity is very low.

In addition, if there are a lot of lipophilic monomolecular acid materials blocked with amines having a high boiling point in the final prepared coating composition, considering that the drying process temperature of a typical food packaging agent is in the range of about 100°C to 120°C , the acidic monomolecular substances blocked by high boiling point amines remain even after the drying process, so the effect of reducing the viscosity or improving water resistance of the protein composition is insufficient. have.

For this reason, in the present invention, sorbic acid, a lipophilic monomolecular acid, was neutralized with ammonia (bp 37.7 ° C., but ammonia does not have a large binding force with organic acids, so even if the neutralized solution is left at room temperature, decomposition and evaporation occur slowly, and when heated, the temperature As the temperature rises, it actively dissociates and evaporates.

According to the results of the study of the present invention, an appropriate dissociation rate appears in the range of 45°C to 60°C, so that it reacts uniformly with the protein. increases, and thus protein precipitation, precipitation, seeding, etc., may occur, and thus the non-uniformity of the protein in the final coating composition may increase.

As a comparative example, when an aqueous solution is prepared by neutralizing a lipophilic monomolecular acid with triethylamine (bp about 89°C) and a protein block is attempted with this aqueous solution, the dissociation temperature of triethylamine is high and the reactivity for the protein block is very high. It is slow, and when the temperature in the reactor is maintained close to 100° C. in order to increase the reaction rate in order to shorten the reaction time, there is a problem in that the polymer protein component is denatured by heat along with rapid water evaporation.

The 20% oleic acid-ammonia aqueous solution may be prepared by mixing 15 to 25 parts by weight of oleic acid, 65 to 75 parts by weight of water, and 8 to 10 parts by weight of an aqueous ammonia solution (NHOH) per 100 parts by weight of oleic acid-ammonia aqueous solution. As the aqueous ammonia solution, an aqueous ammonia solution having a concentration of 25 to 35% may be used. In this embodiment, as a unit by weight, 71 g of water and 9 g of a 28% aqueous ammonia solution (NHOH) are mixed with 20 g of oleic acid to prepare a 20% oleic acid-ammonia aqueous solution paste.

Next, as a second step, a protein mixture is prepared and stirred while heating to sufficiently hydrate (gelatinize) the protein powder in the form of particles. At this time, an 11% protein aqueous solution may be prepared by mixing water and protein in a ratio of 8:1 (S20).

In this embodiment, 800 g of water and 100 g of isolate soy protein (ISP, 99%) are stirred and mixed at room temperature at a linear speed of 4 m/s. Thereafter, the temperature is gradually increased for 1 hour and 30 minutes while stirring the temperature to 90° C. at a linear speed of 4 m/s, and maintained at 90° C. for more than 2 hours. and the reactors (functional groups 1, 2, 3, and 4) inside the isolated soy protein are evenly hydrated in the aqueous solution to ensure a uniform reaction probability. At this time, the stirring temperature is preferably to be a temperature of less than 100 ℃ in the manufacturing process including water, and more preferably to be maintained at 90 ℃.

Next, as a third step, the previously prepared 11% soy protein isolate aqueous solution is cooled to 60° C. over 30 minutes while maintaining a linear speed of 4 m/s (S30). The reason for cooling is to prevent rapid evaporation of ammonia that may occur when 30% sorbic acid-ammonia aqueous solution, which is a previously prepared lipophilic monomolecular acid-ammonia aqueous solution, is added at a high temperature. The higher the reaction temperature in the input process of 30% sorbic acid-ammonia aqueous solution, the more side effects due to excessive dissociation of ammonia, for example, the increase in seeding, precipitation, precipitation, and gloss deterioration.

After that, while maintaining the agitation at a linear speed of 4 m/s, 100 g of the previously prepared 30% sorbic acid-ammonia aqueous solution (30 g as sorbic acid solids) was slowly added to 900 g of the 11% soy protein isolated aqueous solution over about 20 minutes. Prepare a mixture, and stir the first mixture at 45 to 60° C. for at least 4 hours to prepare an aqueous isolated soy protein solution in which sorbic acid is chemically combined with a secondary amine to block functional groups (S40).

In this manufacturing process, if the stirring temperature of the first mixture is higher than 60° C., excess sorbic acid, which has lost its hydrophilicity due to the rapid dissociation of ammonia, is exposed to water, and if the rate is too fast, it excessively reacts with a specific protein molecule in the aqueous solution, Or, the unreacted sorbic acid is not properly dissolved and aggregates, and a large number of insoluble lumps are formed or precipitated by seeding. And, when the stirring temperature is lower than 45° C., the dissociation rate of ammonia is lowered, so that the rate at which sorbic acid blocks the protein functional group becomes very slow, which may cause a problem in that productivity is greatly reduced. Preferably, the stirring temperature is maintained at 60°C.

Next, 150 g of a 12% solids zinc dioxide solution (18 g as solids) was added to the first mixture while stabilizing the temperature in the range of 45 to 60° C. and maintaining a stirring speed of 4 m/s linear speed over about 20 minutes, and 6 hours A fifth step of preparing a second mixture by crosslinking the protein by stirring is performed (S50). At this time, the high molecular protein blocked with sorbic acid in the first mixture is already in a reduced hydrophilicity state.

If the solid content of zinc dioxide added to the aqueous solution in which 30 parts by weight of sorbic acid as a solid content is blocked with respect to 100 parts by weight of the solid content of the isolated soybean protein is greater than 20 parts by weight, the protein polymer that has lost excessive hydrophilicity is precipitated, so that lumps in the final coating composition may occur. Zinc dioxide is preferably contained in an amount of 10 to 20 parts by weight based on 100 parts by weight of the isolate soy protein solid content (130 parts by weight of the total protein solids blocked by sorbic acid when quantified including sorbic acid).

At this time, the zinc dioxide contained in the zinc dioxide solution serves as a crosslinking agent and a water repellent agent. When the stirring temperature is higher than 60°C, zinc dioxide is precipitated in the second mixture after stirring, and a large number of lumps are generated. There may be a problem in that the time required for the process increases rapidly, which leads to an increase in manufacturing cost. This is a problem stemming from the properties of the neutralizing agent, ammonia, and not the properties of zinc dioxide.

The preferred stirring temperature set in the present invention is to stir for at least 6 hours while maintaining 45 ℃. If the temperature is maintained at 60°C, the reaction time can be shortened to about 4 hours, but residues may increase during fine seeding and filtering, which may cause difficulties in the filter process. In order to prevent possible difficulties during mass production, the reaction temperature was lowered to 45℃, and this reaction temperature is not an absolute temperature. In this case, the 12% zinc dioxide solution may be a 12% zinc dioxide-ammonia-bicarbonate aqueous solution, and BASF's ZINC OXIDE SOLUTION #1 may be used, but the present invention is not limited thereto.

Next, a sixth step ( After performing S60), the seventh step (S70) of filtering the patched protein aqueous solution by filtering with a fine mesh such as a #300 filter or a Cuno filter of 5 μm or less is performed to improve the water resistance according to an embodiment of the present invention. Improved aqueous protein solutions can be prepared.

In addition, in order to complete the preparation of the coating composition, the eighth step (S80) of adding a lipophilic filler to the aqueous protein solution (second mixture) with improved water resistance prepared by the above process should be performed. In this case, the filler may be at least one of aliphatic monohydric alcohols such as cetyl alcohol, aliphatic monohydric acids such as oleic acid, and polyacids such as maleic acid and phthalic acid, but the present invention is not limited thereto.

As the lipophilic filler of this example, an oleic acid-ammonia aqueous solution paste having a solid concentration of 20% was used.

The 20% oleic acid-ammonia aqueous solution paste may be prepared by mixing 15 to 25 parts by weight of oleic acid, 65 to 75 parts by weight of water, and 8 to 10 parts by weight of an aqueous ammonia solution (NHOH) per 100 parts by weight of oleic acid-ammonia aqueous solution. As the aqueous ammonia solution, an aqueous ammonia solution having a concentration of 25 to 35% may be used. In this example, as a unit by weight, a 20% oleic acid-ammonia aqueous solution was prepared by mixing 71 g of water and 9 g of a 28% aqueous ammonia solution (NHOH) with 20 g of oleic acid. It was used as a filler.

Experiment example

Hereinafter, various properties according to the components of the coating composition will be compared and described.

1) Preparation of semi-finished intermediate composition

Table 1 below shows the components and contents for preparing the intermediate intermediate, and as shown in Table 1, as an intermediate for preparing the composition for coating of this example, 36.5 g of water (DW) is mixed with 30 g of sorbic acid at room temperature, and , while stirring at a linear speed of 2 m/s or less, slowly add 33.5 g of 28% aqueous ammonia solution (NHOH) to prepare 30% sorbic acid-ammonia aqueous solution, and after cooling, filter with a mesh #300 mesh and pack . Then, 20 g of oleic acid was mixed with 71.1 g of water at room temperature, 8.9 g of 28% aqueous ammonia solution (NaOH) was added while stirring at a linear speed of 2 m/s or less, and the mesh was stirred at a linear speed of 4 m/s for 2 hours. Filter and wrap with # 100 mesh to prepare a 20% oleic acid-ammonia aqueous solution paste.

Preparation table for neutralized aqueous solution of lipophilic acid. Ingredient name 30% sorbic acid
aqueous solution (g) 20% oleic acid
aqueous solution (g) M.W. One Sorbic Acid 30.0 - 112.13 2 Oleic Acid - 20.0 282.46 3 28% NH4OH 33.5 8.9 125.14 4 D.W. 36.5 71.1 - Total 100.0 100.0 - NV(%) 30.0 20.1 - Appearance of aqueous solution pale yellow transparent milky white paste viscosity of aqueous solution 30 or less over 50,000 cP.s

2) Preparation of coating composition

Table 2 below shows the components and contents of the coating composition. As shown in Table 2, 800 g of water and 100 g of isolated soybean protein were first stirred at room temperature with a mechanical stirrer, and then the temperature was raised to 90° C. for 2 hours. During the second stirring, an 11% aqueous protein solution is prepared. In Table 2, () indicates the weight of the actual solid content.

After that, 100 g of 30% sorbic acid-ammonia aqueous solution (30 g of pure sorbic acid solid content) was further added to each sample, mixed with 900 g of 11% protein aqueous solution to make 1 kg mixture, and 3rd stirring at 60 ° C. for 4 hours to prepare the first mixture and (#1), 150 g of a 12% zinc dioxide solution (18 g of solids of pure zinc dioxide) was added to the first mixture, followed by fourth stirring at 45° C. for 6 hours to prepare a second mixture (# 2), and then The second mixture is cooled to room temperature and filtered through a fine mesh to prepare a coating composition in which a filler is not mixed.

That is, Example #1 contains 100 g of isolate soy protein and 100 g of 30% sorbic acid-ammonia aqueous solution (30 g parts by weight as pure sorbic acid), 150 g of 12% zinc dioxide aqueous solution (18 g parts by weight as pure zinc dioxide) and a filler. 250 g of 20% oleic acid-ammonia aqueous solution (the weight of pure oleic acid is 50 parts by weight based on 100 parts by weight of protein).

#2-9 are comparative examples.

#2-6 was prepared to compare the performance change of the coating composition according to the inclusion of the filler, the type of filler, and the amount used.

#2 contains 100 g of isolate soy protein and 100 g of 30% sorbic acid-ammonia aqueous solution (30 g parts by weight as pure sorbic acid), but no crosslinking agent and filler.

#3 added 150g of 12% zinc dioxide aqueous solution (18g parts by weight as pure zinc dioxide) compared to #2, and no filler was included.

In #4, compared to #1, a 20% oleic acid-ammonia aqueous solution, which is a lipophilic fatty acid, 250g (the weight of pure oleic acid was 50 parts by weight based on 100 parts by weight of protein) was further added. #4 is an example to compare the performance change according to the excessive use of the lipophilic filler.

#5 and #6 are examples for comparing oleic acid, which is a lipophilic filler, and sorbitol, which is a hydrophilic filler.

#7-9 does not contain sorbic acid and zinc dioxide solution. This was prepared for performance comparison of protein compositions with improved water resistance and intrinsic properties of unmodified pure soy protein.

#7 is a 10% aqueous solution with a protein concentration containing 900 g of water and 100 g of soy protein, without sorbic acid, zinc dioxide solution and filler, #8 contains 1900 g of water and 100 g of soy protein, sorbic acid, zinc dioxide solution, and It is a 5% aqueous solution with a protein concentration that does not contain a filler, and is prepared to measure the change in viscosity over time according to the concentration of the protein, measure the oxygen permeability and compare the water resistance when the protein is alone.

#9 contains 800 g of water, 100 g of soy protein and 100 g of sorbitol, does not contain sorbic acid and zinc dioxide solution, and is a mixture of 100 g of protein and 100 g of sorbitol, a hydrophilic polyhydric alcohol, and #7 and #8, which are aqueous solutions of protein alone. It was prepared to measure the change in viscosity, comparison of water resistance, and oxygen permeability when protein and sorbitol were mixed in comparison with sorbitol.

Preparation chart of each composition division Example comparative example One 2 3 4 5 6 7 8 9 One water 800 800 800 800 800 800 800 800 800 2 Soy Protein Powder 100 100 100 100 100 100 100 100 100 3 water 100 1100 4 30% sorbic acid aqueous solution 100 100 100 100 100 100 5 12% Zinc Dioxide Solution 150 150 150 150 150 6 20% oleic acid solution 250 500 7 100% Sorbitol Powder 50 100 100 synthesis 1400 1000 1150 1650 1200 1250 1000 2000 1000 of the whole composition
Protein content (%) 7% 13% 7% 8% 8% 8% 10% 5% 10% Total weight of protein (g) 100 100 100 100 100 100 100 100 100 Total weight of sorbic acid (g) 30 30 30 30 30 30 - - - Total weight of zinc dioxide (g) 18 - 18 18 18 18 - - - Total weight of oleic acid (g) 50 - - 100 - - - - - Total weight of sorbitol (g) - - - - 50 100 - - 100 NV (%) Total composition 14 13 12.8 20 20 14 10 5 20

3) Viscosity measurement

As a storage stability measure for the coating composition prepared according to #1-9, the viscosity was measured at room temperature and humidity (20±5° C., 55±5%) using a Brookfield, DV-± viscometer (spindle: No. 63, rpm: 10rpm), the initial viscosity at a temperature of 24° C. and a humidity of 51% and the viscosity after 2 weeks of storage were measured.

Viscosity measurement results according to the storage period of each composition. Viscosity Example comparative example #One #2 #3 #4 #5 #6 #7 #8 #9 One Day 1 899 815 108 959 72 84 2627 60 4500 2 Day 2 2351 10600 108 983 84 84 15000 150 16000 3 Day 3 2975 10800 96 851 84 96 19000 565 28000 4 1 week later 3400 10830 108 720 96 96 38700 1176 29000 5 2 weeks later 2927 10600 108 780 96 96 57000 120 17000 6 after 3 weeks 3059 10600 96 800 96 84 Gel Corruption Gel 7 after 4 weeks 3065 10300 98 790 94 88 - - - 8 6 months later 3150 9800 100 750 96 82 - - - 9 after 12 months 3230 10100 95 760 93 94 - - -

When the viscosity values of #1, #2, #3 and #7, #8 are compared with reference to Table 3, when the content of protein in the total amount of the total composition is lowered, there is a phenomenon that the viscosity is also lowered in the same direction.

Comparing aqueous solutions with similar protein concentrations, it can be seen that #2 modified by adding 30 parts by weight of sorbic acid as compared to aqueous solution #7 with protein alone has a lower viscosity and is very stable without changing over time during storage.

It can be seen that #3, in which 18 parts by weight of zinc dioxide is added to #2, has a lower viscosity compared to #2 and is also very stable over time.

#1, in which 50 parts by weight of oleic acid, a lipophilic monobasic acid, was added to #3, the viscosity was increased compared to #3, but it can be seen that the change over time is very stable. This is thought to be a natural phenomenon that occurs when the aqueous solution of oleic acid, a lipophilic substance, is a milky white paste with a very high viscosity, and the low-viscosity aqueous protein solution is mixed with the high-viscosity aqueous solution of oleic acid.

#4 is a comparative example in which an excess of oleic acid aqueous solution was added to #1. In this case, the viscosity of the composition is further lowered, which is accompanied by problems such as haze, reduced gloss, and precipitation as excessive incompatibility occurs in the composition and shock is induced due to excessive use of the oleic acid aqueous solution paste, which is a lipophilic material. is a phenomenon that appears In the case of excessive use of lipophilic monomolecules such as sorbic acid and zinc dioxide, there is a phenomenon in which the viscosity is abnormally lowered in proportion to problems such as deterioration of gloss, haze, and precipitation.

#5 and #6 are comparative groups in which lipophilic oleic acid is replaced with hydrophilic sorbitol compared to #1 and #4. Sorbitol, a hydrophilic substance that dissolves well in water, has very good compatibility with aqueous protein solutions, so it is related to the amount of sorbitol used. It shows a very low viscosity without In this case, the viscosity stability of the composition is also very good, and there are no problems of gloss deterioration, seeding, or haze at all, but the water resistance problem of the dry coating film is not improved.

#7 is a protein concentration of 10%, and #8 is a composition having a protein concentration of 5%. #9 is a case in which sorbitol is mixed with a protein concentration of 10%. Even in this case, sorbitol had little effect on the viscosity of the aqueous protein solution.

#7 and #9 increased their viscosity very quickly during storage and gelled after about 3 weeks.

In the case of #8, the protein concentration was lower than that of #7, so the initial viscosity was very low, but the viscosity increased rapidly over a period of about one week. However, the viscosity of the composition began to decrease with the occurrence of decay, and in this case, it was impossible to specify a significant viscosity value.

Referring to Table 3, when the composition for coating (#1-6) according to the embodiment contains sorbic acid and zinc dioxide solution (#1-6), the viscosity change rate is less than 110%, and the viscosity is measured after 2 weeks It can be seen that the viscosity change rate is significantly lower than that of Comparative Example #7-9, which is not possible or the viscosity change rate after 1 week exceeds at least 1000%, so that the storage stability is also excellent. In particular, in the case of #7, which reproduces the conventional technique, gelation occurred in which the entire reactant was hardened after 3 weeks, and measurement with a viscometer was impossible. In the case of #9 using sorbitol, gelation occurred after 3 weeks, and measurement with a viscometer was impossible.

4) Evaluation of liquid stability of the coating composition

In order to compare the degree of decay according to the presence or absence of sorbic acid, each of Examples (#1-6) and Comparative Example (#7-9) were put in a container and sealed, and then under normal temperature and humidity conditions (temperature 20±5℃, humidity 55). The timing and degree of decay of the coating composition were observed over time while stored at ±5%), and the results are shown in Table 4 and FIGS. 5A to 13B.

Figures 5a and 5b show a photograph 1 day after production of #1 and a photograph 8 weeks after production, Figures 6a and 6b are a photograph 1 day after production of #2 and 8 weeks after production Figures 7a and 7b show a photograph 1 day after production of #3 and a photograph 8 weeks after production of #3, and FIGS. 8a and 8b are 1 day after production of #4 The rear photograph and the photograph after 8 weeks after production are shown, and FIGS. 9A and 9B are the photograph 1 day after production of #5 and the photograph 8 weeks after production, and FIGS. 10A and 10B is a photograph of #6 one day after production and a photograph eight weeks after production, and FIGS. 11A and 11B are a photograph of one day after production of #7 and a photograph three weeks after production of #7. 12a and 12b show a photograph one day after production of #8 and a photograph three weeks after production of #8, and FIGS. 13A and 13B are photographs and a photograph one day after production of #9 The picture was taken after 7 weeks had elapsed.

The timing of spoilage according to the storage period of each composition. Viscosity Example comparative example #One #2 #3 #4 #5 #6 #7 #8 #9 One 1 week later ○ ○ ○ ○ ○ ○ ○ ○ ○ 2 2 weeks later ○ ○ ○ ○ ○ ○ △ X △ 3 3 weeks later ○ ○ ○ ○ ○ ○ X - △ 4 4 weeks later ○ ○ ○ ○ ○ ○ - - X 5 after 8 weeks ○ ○ ○ ○ ○ ○ - - 6 3 months later ○ ○ ○ ○ ○ ○ - - - 7 6 months later ○ ○ ○ ○ ○ ○ - - - 8 after 12 months ○ ○ ○ ○ ○ ○ - - -

(○ = good, △ = onset of corruption, X = apparent corruption)

Referring to Table 4 and FIGS. 5A to 13B, in the case of #7-8, a comparative example that does not contain sorbic acid and zinc dioxide solution, decay occurred in the coating composition after 2 weeks, and sorbic acid and zinc dioxide solution were not included. In the case of Comparative Example #9 containing sorbitol, corruption occurred in the coating composition after 3 weeks, and in the case of Example #1-6 containing sorbic acid, it was confirmed that decay did not occur even after 8 weeks. In the case of #2, which does not contain a dioxide solution, there was a slight thickening phenomenon in which weak thixotropy was observed at one week after manufacture.

5) Preparation of coating film

After attaching a 38 μm thick base film (PET) to the glass plate of the coater, drop about 1-2.5 g of the coating composition prepared according to #1-9 on the upper part of the base film, and then drop the bar coater # 3 (Mayer bar) was used to apply the coating composition to the base film to a certain thickness (dry film thickness: DFT about 1㎛). Then, the coating film of #1-9 was prepared by drying the film coated with the coating composition at 120° C. for 3 to 5 minutes using a hot air dryer.

6) Measurement of oxygen and moisture visible light transmittance and adhesion

With respect to the coating film prepared according to #1-9, the amount of oxygen passing through the coating film within a certain time (24 hours) _{at a temperature of 23° C. and O 2 100% using an oxygen permeability meter was measured and shown in Table 5 below} indicated. In addition, the adhesion of each coating film was tested through a measurement of water permeability, a measurement of visible light transmittance, and a cross cutter test, and the results are shown in Table 5.

Table of physical properties test results of the coated film. Classification(#) oxygen permeability
(cm ³ /m ² day) water permeability
(g/m ² days) Transmittance (%)
(visible light) Adhesion (EA)
(PET) #One 0.1~0.3 28-35 90.6 97/100 #2 80-85 85-90 91.0 70/100 #3 55 to 60 65-70 90.6 80/100 #4 0.5~0.8 16-20 82.5 85/100 #5 0.3~0.5 100 or more 91.2 95/100 #6 0.3~0.5 100 or more 90.1 88/100 #7 100 or more not measurable 90.5 60/100 #8 100 or more not measurable 90.8 62/100 #9 0.3~0.5 not measurable 90.2 83/100

Referring to Table 5, #7, 8, and 9 were dissolved by water, so it was impossible to measure the water permeability. The oxygen permeability of the coating films according to #1, 4, 5, 6, and 9 were all 0.1 to 0.8 cm ³ /m ² day (1 or less), indicating that they had excellent barrier properties. In addition, #2, 3, 7, and 8 without fillers lack oxygen barrier properties, but protein crosslinked #2 and #3 have improved oxygen barrier properties compared to #7 and #8.

7) Possible side effects from excessive use of lipophilic fillers

14 is a photograph showing that a defective phenomenon due to incompatibility occurs in a dry coating film when an excessive amount of a hydrophobic material is used. The compositions prepared in #1 and #4 were coated with Mayer bar #3 on a 100 μm PET film and dried by heating at 120° C. for 3 minutes with a hot air dryer to prepare a film having a dry film thickness of about 1 μm. Then, it was left for 3 hours in an environment of 25 ℃ room temperature and 75% humidity.

Referring to FIG. 14 , it can be seen that, when an excessive amount of a lipophilic material is used as in #4, haze and a decrease in gloss occur in the dried coating film due to an increase in incompatibility. Although the same lipophilic filler was used, no defects occurred in composition #1 using an appropriate content. It can be estimated that when a packaging film is manufactured using a composition containing an excess of lipophilic filler, it may adversely affect product appearance and visible light transmittance in the manufacturing and distribution process of the final film. Therefore, it can be seen that the preferred amount of oleic acid used is less than 100 parts by weight based on 100 parts by weight of the protein solid content in the aqueous protein solution whose water resistance is modified with sorbic acid and zinc dioxide. The correct amount of the lipophilic filler to be used should be determined by comparing the filler content according to the type of the modified protein aqueous solution.

8) Hydrophobicity measurement and water resistance comparison.

Hydrophobicity can be expressed as a contact angle. In order to compare the hydrophobicity of the surfaces of the prepared coating films, the surface contact angle of the films coated with each composition was measured. Table 6 shows the measured contact angles. The contact angle was measured using a Kruss contact angle measuring instrument (model name: DSA 30).

In addition, about 0.5 g (3 drops) of water droplets were dropped on the dry coating film, left at room temperature for 10 minutes, and then the water droplets were wiped off to observe the phase change of the contact area of the droplets.

Compositions #7, 8, and 9 were dissolved by water after 2 minutes of the dry coating film on the spot where the water droplet fell.

Measurement result of contact angle of droplet of each composition Classification(#) Droplet contact angle measurement (60 seconds) Water resistance against water drops (after 10 minutes) #One 75.3° Good #2 64.8° Good #3 68.9° Good #4 83.8° Good #5 47.7° Good (reduced gloss) #6 43.0° Good (reduced gloss) #7 60.3° Dissolved within 2 minutes #8 61.3° Dissolved within 2 minutes #9 57.1° Dissolved within 2 minutes

The present invention is not limited by the above-described embodiment. Accordingly, various types of substitution, modification and change will be possible by those skilled in the art within the scope not departing from the technical spirit of the present invention described in the claims, and it is also said that it falls within the scope of the present invention. something to do.

Claims (12)

protein; and
lipophilic monomolecular monoacid; including,
The lipophilic monomolecular monoacid is combined with a secondary amine (-NH-) in a protein molecule through a covalent bond by a neutralization reaction to block the amine group of the protein. A composition for coating comprising a protein with improved water resistance. According to claim 1, wherein the coating composition further comprises a crosslinking agent and a filler, and neutralizing the lipophilic monomolecular monoacid, the crosslinking agent and the filler with ammonia to improve compatibility with an aqueous protein solution, block reaction rate and crosslinking A coating composition comprising a protein having improved water resistance by controlling the reaction rate. [Claim 3] The composition for coating according to claim 1 or 2, comprising a protein having improved water resistance comprising a repeating unit represented by the following formula (1).
<Formula 1>

In Formula 1, functional group 1 and functional group 3 are binding sites in a protein molecule capable of binding to an acidic substance, respectively. The coating composition of claim 1 or 2, wherein the lipophilic monomolecular monohydric acid is blocked with one of sorbic acid and benzoic acid as blocking agents. composition. The method according to claim 1 or 2, wherein zinc oxide solution, malic acid, citric acid, maleic acid are used as a cross linker to improve the physical durability of the dry coating film of the composition. Acid), maleic anhydride, and phthalic acid (Phthalic acid), one or two or more of a mixture containing a composition for coating comprising a protein with improved water resistance. According to claim 5, wherein the lipophilic monomolecular monoacid and polyacid to neutralize the monoacid and polyacid and the lipophilic monomolecular monoacid and polyacid and the molar ratio of 1: 1 to 28% aqueous ammonia containing a protein with improved water resistance. A composition for coating. According to claim 1 or 2, wherein the protein, whey protein isolate (9410 WPI), whey protein concentrate (8000 WPC), soy protein isolate (Isolated soy protein, ISP), rice protein (rice protein isolate, RPI) , Oat protein (oat protein isolate, OPI), pea protein (pea protein isolate, PPI), corn protein (Corn zein), including any one or more selected from the group consisting of a protein containing improved water resistance A composition for coating. According to claim 1 or 2, wherein the lipophilic monomolecular monohydric acid is sorbic acid,
The protein contains 5 to 15 parts by weight based on 100 parts by weight of the coating composition,
The sorbic acid is a coating composition comprising a protein with improved water resistance included in a ratio of 10 to 30 parts by weight based on 100 parts by weight of the solid content of the protein. According to claim 1 or 2, further comprising zinc oxide (Zinc oxide), wherein the zinc dioxide is contained in a ratio of 10 to 20 parts by weight based on 100 parts by weight of the protein solid content containing a protein with improved water resistance. A composition for coating. According to claim 1 or 2, further comprising a lipophilic filler (Fillers),
The filler, an aliphatic monohydric acid, and a coating composition comprising a protein with improved water resistance of at least one of an aliphatic monohydric alcohol. A first step of preparing a 30% sorbic acid-ammonia aqueous solution by adding sorbic acid and an aqueous ammonia solution to water;
a second step of mixing water and protein in a ratio of 8:1, raising the temperature to 90°C for 1 hour and 30 minutes, and then stirring at 90°C for 2 hours or more to prepare an 11% aqueous protein solution;
a third step of cooling the 11% aqueous protein solution to 60°C;
The 30% sorbic acid-ammonia aqueous solution was added to the 11% protein aqueous solution to prepare a first mixture, and the first mixture was stirred for 4 hours or more while maintaining 45 to 60° C. a fourth step of blocking the functional group of the protein by binding;
a fifth step of preparing a second mixture by adding a 12% zinc dioxide solution to the first mixture and further stirring at 45 to 60° C. for 6 hours or more to cross-link the protein;
a sixth step of cooling the second mixture to room temperature;
a seventh step of filtering the second mixture; and
an eighth step of adding a filler to the second mixture; A method for producing a coating composition comprising a protein with improved water resistance comprising a. The method of claim 11, wherein the protein comprises 5 to 15 parts by weight based on 100 parts by weight of the coating composition, and the sorbic acid comprises a protein with improved water resistance including 10 to 30 parts by weight based on 100 parts by weight of the protein. A method for preparing a composition for coating.

Images