Heat-resistant and oil-resistant food tray paper

Abstract

The present invention relates to a high-temperature, heat-resistant, and oil-resistant food tray paper that is suitable for use in ovens and air fryers and has high recyclability, as well as a method for manufacturing the same. To address the lack of heat resistance and recycling issues associated with conventional polyethylene coatings, the present invention applies a three-stage coating process—undercoating, top coating, and back coating—to the paper. The undercoating secures barrier properties through pigment coating, while the top coating imparts oil resistance and heat resistance by using oil-resistant modified starch and water-resistant surface strength reinforcing additives. The back coating ensures paper curl control and strong water resistance. Through this, the invention provides a disposable food tray paper that can be used stably even at high temperatures of 180°C to 200°C, offers excellent processability such as adhesive bonding, is environmentally friendly based on natural compounds, and is recyclable.

Description

Technology Field

[0001] The present invention relates to a heat-resistant oil-resistant tray paper that is recyclable with secured dissociability and can be used as a disposable container and for safe storage of food processed at high temperatures such as ovens and air fryers, and a method for manufacturing the same. Background Technology

[0002] The market for disposable containers is experiencing explosive growth due to their convenience and time-saving benefits. Currently, among disposable containers, polyethylene-coated products are the mainstream among paper-based options to address hygroscopicity issues. Polyethylene is used in various household goods due to its lightweight nature, excellent chemical stability, water resistance, flexibility, insulation, and moldability. While products utilizing this material offer superior food hygiene and economic efficiency, as well as various performance capabilities such as heat sealing, they have the disadvantage of poor heat resistance. Furthermore, they are non-recyclable; incineration causes air pollution such as smoke, and landfilling takes hundreds of years to decompose, posing a problem that contributes to soil contamination.

[0003] To address these issues, switching from conventional polyethylene to acrylic-based materials offers environmental advantages such as recyclability and rapid natural decomposition when landfilled; however, due to significant price increases compared to polyethylene, it remains in the market introduction stage.

[0004] The air fryer market has been growing rapidly recently, and since they operate at temperatures of 180°C to 200°C—higher than those of microwave ovens—polyethylene or acrylic-based oil-resistant agents cannot be used. Additionally, there is an increasing trend in bakeries to bake and sell bread directly, aiming to appeal to customers with the freshness and taste of freshly baked goods and differentiate themselves from competitors. These market changes are diversifying into specialized bakery sections within convenience stores and shop-in-shop formats within franchise stores. While oven temperatures for baking bread are high, ranging from 170°C to 230°C, which is close to the melting point of general polyethylene (110°C), methyl methacrylate resin, used in recyclable water-based paper cups, is difficult to use at temperatures above 160°C to 180°C due to the generation of odors and smoke.

[0005] Currently, silicone-coated or impregnated paper foil is used as a product capable of withstanding such high temperatures. Paper foil is primarily used in low basis weight products ranging from 30 g / m² to 80 g / m², while high basis weight products of 200 g / m² or more are difficult to produce due to high coating volume and drying loads. Although silicone coating offers excellent heat resistance and thermal stability, the raw materials cannot be recycled, and it is very difficult to form them into container shapes. In particular, due to the high release properties of silicone coating, adhesion is difficult during the process of making containers using adhesives, such as paper trays. This makes it difficult to produce containers with complex shapes, and there is a disadvantage that only simplified containers in the form of molds can be manufactured.

[0006] Therefore, the most widely used alternative in the current market is a coating method utilizing fluorine-based oil-resistant agents. However, as controversies regarding the harmful effects of fluorine-based oil-resistant agents persist and regulations are spreading globally, a technical approach to utilizing new materials is urgently needed.

[0007] Recently, research on securing barrier properties using nanocellulose, a fiber-based raw material, has been actively underway and has been shown to be advantageous in terms of heat resistance and barrier properties. However, since nanocellulose is very expensive, has a high viscosity increase rate, and requires consideration of the effects of chemicals depending on the manufacturing method, it is expected that it will take a long time to commercialize.

[0008] In conclusion, to develop oil-resistant paper suitable for air fryers or ovens while considering market demand for eco-friendliness, and which is economical and commercially viable, it is essential to address issues of paper recyclability, human health hazards, and workability, such as adhesive adhesion. Prior art literature

[0009] US Patent Publication US10519604B2 The problem to be solved

[0010] The present invention aims to solve the problems of the aforementioned prior art. Specifically, it secures the recyclability of paper while possessing heat resistance capable of withstanding high-temperature ovens or air fryers of 180°C to 200°C. Furthermore, it aims to provide convenience as a stable disposable container from the moment bread is baked in the oven until it is delivered to and stored by developing paper that satisfies workability qualities, such as glue bonding, required in the paper tray processing process. means of solving the problem

[0011] The oil-resistant agents used to achieve the aforementioned objectives actually have many limitations. In particular, oil-resistant agents capable of exhibiting heat resistance are extremely limited, and most are naturally derived products rather than chemically synthesized ones. Generally, modified products of naturally derived materials such as starch and hydroxypropyl methylcellulose, or substances like polyvinyl alcohol and styrene-butadiene latex, can be used. However, these agents exhibit oil resistance through chemical modification rather than possessing it inherently; since their effectiveness is significantly lower than that of existing products, they are difficult to use alone and require a separate processing step.

[0012] In the present invention, the coating of the paper is performed three times.

[0013] First, the primary coating, which is the undercoating (12), is applied in an amount of 6 g / m² to 30 g / m² to ensure barrier properties, thereby allowing the top coating (13) agent to remain perfectly on the paper surface. The undercoating (12) is mainly performed by applying a general pigment coating or an agent capable of forming a barrier. In the case of the pigment coating, suitable pigments such as clay, calcined clay, calcium carbonate, and coating talc are used, along with binders such as styrene-butadiene latex and other additives such as dispersants, flow improvers, water retention enhancers, water-resistant agents, and color pigments. In the case of the barrier coating, agents such as polyvinyl alcohol, which can generally improve air permeability, are used in combination rather than alone. If the amount of undercoating (12) applied is too low, the top coating (13) liquid penetrates into the paper, making it difficult to form a perfect barrier; if it is excessive, it increases costs and requires drying a large amount of water, which makes actual production difficult due to the load on the dryer, so it is necessary to adjust the amount of application appropriately. The undercoating (12) is applied using blade coating, rod coating, or air knife coating, etc.

[0014] Second, the purpose of the secondary coating, which is the top coating (13), is to enable oil resistance and heat resistance. The top coating (13) uses oil-resistant modified starch, and 0.2% to 5% of alkyl ketene dimer is added relative to the starch to reinforce water resistance. Additionally, because the product surface is susceptible to scratches and wear, 0.5% to 5% of a water-resistant agent or starch hardener is added to supplement the surface strength of the top coating (13) to ensure oil resistance and water resistance, and the coating amount is set to 2g / ㎡ to 7g / ㎡. The top coating (13) is also applied using blade coating, rod coating, or air knife coating, and it is also possible to utilize gravure for some applications. In the case of oil-resistant starch, since its oil resistance is weaker than that of conventional oil-resistant agents, it can only be used directly in low basis weights of 20g / ㎡ to 60g / ㎡, and for oil-resistant trays of 200g / ㎡ to 300g / ㎡, the amount of penetration into the paper is too large, making it difficult to process directly. Therefore, a method is used in which oil-resistant starch is left on the surface through a primer-type undercoating (12), and then the starch is coated with a top coating (13).

[0015] Third, the third coating, which is a back coating (14), is primarily intended to control the curl of the paper after coating and to ensure strong water resistance to prevent wetting caused by condensation during refrigeration or freezing. While white non-fluorescent paper, such as food paper or cup paper base paper (11), is mainly used, it is acceptable to use kraft paper in accordance with recent trends. Cup paper base paper (11) has strong internal sizing to prevent edge wicking, so there is no problem, but if the sizing level of the base paper (11) among non-fluorescent paper types is low, sizing can be added in the back coating (14) to compensate for the product characteristics. In particular, since domestic bakery products contain a lot of vegetables, if water resistance is weak, customer complaints may arise due to wetting on the surface or back under refrigeration or freezing conditions; therefore, improving water resistance is essential for domestic products.

[0016] After coating, the material is dried using a dryer (2), which is a drying facility. The hot air used at this time is affected by speed, but the temperature effect is minimal, such as with silicon or fluorine-based materials, so it can be adjusted according to the amount of material being dried. Effects of the invention

[0017] The oil-resistant tray base paper according to the example of the present invention is composed mostly of natural compounds, so there are no problems with resource recycling, and it is capable of natural decomposition when landfilled. In addition, the workability during the manufacturing process, such as paper glue bonding, is similar to existing products, and it retains the heat resistance of natural materials, allowing it to be used even at high temperatures of 180°C to 200°C. This enables the use of air fryers and allows for the production of trays that can be used for baking bread in some bakeries. Brief explanation of the drawing

[0018] Figure 1 shows the coating structure of the paper of the present invention. Figure 2 shows a schematic diagram of the field equipment for the coating processing method of the paper of the present invention. Figure 3 shows the results of a heat resistance test under conditions of 200°C for 30 minutes in an air fryer. Specific details for implementing the invention

[0019] The present invention will be described in detail below. These examples are for the purpose of explaining the present invention and are not intended to limit the present invention. Unless otherwise specifically indicated, the terms parts and percentages are read as parts by weight and weight percentages, respectively.

[0020] The high temperature heat-resistant and oil-resistant food tray paper of the present invention is composed of a base paper (11), an undercoating layer (12), and a top coating layer (13) as shown in FIG. 1, and additionally includes a back coating layer (14) as needed.

[0021] The base paper (11) is a white non-fluorescent paper, such as food paper or cup paper, and it is also possible to use kraft paper according to recent trends. In the case of cup paper base paper (11), there is no problem as the internal sizing is strong to prevent edge wicking, but in the case of non-fluorescent paper, the sizing level of the base paper (11) is often low, in which case the characteristics of the product can be supplemented by adding sizing in the back coating (14).

[0022] The undercoating layer (12) is formed on the upper surface of the base paper (11) and includes pigment and binder. The pigment of the undercoating layer (12) is one or more selected from the group consisting of clay, fired clay, talc, and calcium carbonate. The binder includes styrene-butadiene latex or styrene-acrylic latex, and the binder is included in an amount of 7 to 15 parts by weight per 100 parts by weight of pigment. The application amount of the undercoating layer (12) is 6 to 30 g / m². The undercoating layer (12) secures barrier properties so that the top coating (13) chemical can remain perfectly on the paper surface.

[0023] The top coating layer (13) is formed on the upper part of the under coating layer (12) and comprises oil-resistant modified starch, alkyl ketene dimer, and a starch curing agent. The alkyl ketene dimer is added in an amount of 0.2% to 5% relative to the starch to reinforce water resistance. The starch curing agent is added in an amount of 0.5% to 5% to reinforce surface strength. The top coating layer (13) exhibits heat resistance at high temperatures of 180°C to 200°C. The coating amount of the top coating layer (13) is at a level of 2g / m² to 7g / m².

[0024] The undercoating layer (12) and the top coating layer (13) are formed by blade coating, rod coating, or air knife coating. Some may also utilize gravure coating.

[0025] The back coating layer (14) is formed on the lower rear surface of the base paper (11) and contains starch and alkyl ketene dimer. The alkyl ketene dimer is 0.5 to 100 parts by weight of starch. 2.5It is included in weight percent. The back coating layer (14) is intended to control the curl of the paper after coating and serves to ensure strong water resistance to prevent wetting caused by condensation during refrigerated or frozen storage.

[0026] The manufacturing method of the present invention will be explained with reference to FIG. 2. FIG. 1 shows the coating structure of the paper of the present invention. FIG. 2 shows a schematic diagram of the field equipment for the coating processing method of the paper of the present invention.

[0027] As shown in FIG. 1, the undercoating (12) is coated with pigments using a heat-resistant material to improve the coverage of the paper surface, and the top coating (13) utilizes oil-resistant modified starch, etc. to provide oil resistance and water resistance, and supplements the lack of water resistance and surface strength. The back coating (14) is primarily intended to control the curl of the paper after coating the top surface, and secures strong water resistance to prevent wetting caused by condensation during refrigeration or freezing storage.

[0028] FIG. 2 shows a schematic diagram of equipment for implementing such a product. The coating unit performs coating using a chemical transfer roll (1) that transfers the chemical, a rubber roll which is a backing roll (4) for coating on paper, and a metering unit (3) for subsequent metering, utilizing equipment such as a rod, blade, and air knife. The pre-metering unit (5) is responsible for pre-regulating the amount of coating. This can also be done using gravure coating.

[0029] The manufacturing process is as follows. First, a base paper (11) to be processed is prepared. An undercoating is applied as a primary coating (12) to the upper surface of the base paper (11). The undercoating (12) is applied by transferring a coating liquid containing pigment and binder to the base paper (11) through a chemical transfer roll (1) and a backing roll (4), and controlling the amount of application with a metering unit (3) to apply it in a coating amount of 6 g / m² to 30 g / m² using a blade coating, rod coating, or air knife coating method. After the undercoating (12), it is dried through a dryer chamber (2), which is a drying facility.

[0030] Next, a top coating is applied as a secondary coating (13) on top of the undercoating layer (12). The top coating (13) is applied by transferring a coating solution containing oil-resistant modified starch, alkyl ketene dimer, and starch curing agent through a chemical transfer roll (1) and a backing roll (4), and controlling the amount of application with a metering unit (3) to apply a coating amount of 2 g / m² to 7 g / m² using a blade coating, rod coating, or air knife coating method. After the top coating (13), it is dried through a dryer chamber (2).

[0031] If necessary, back coating is performed on the lower rear surface of the base paper (11) as a third coating (14). The back coating (14) is applied by applying a coating solution containing starch and an alkyl ketene dimer. After back coating (14), it is dried through a dryer chamber (2).

[0032] After coating, the material is dried through a dryer chamber (2). The hot air used at this time is affected by speed, but the temperature effect is minimal, such as with silicon or fluorine-based materials, so it can be adjusted according to the amount of material being dried.

[0033] Figure 3 shows the results of a heat resistance test under conditions of 200°C for 30 minutes in an air fryer. In the case of the comparative example, a water-based acrylic coating, it was observed that smoke was generated at high temperatures, and the oil-resistant agent deformed and the color changed. On the other hand, the fluorine-based and the starch-based of the present invention showed no unusual characteristics at high temperatures as oil-resistant materials, and it was confirmed that the materials utilizing starch and pigments also withstood high temperatures. This is inferred to be due to the characteristics of natural compounds.

[0034] The test method used in the example is as follows.

[0035] The water resistance test uses the TAPPI T-205 method, a cob test. This test evaluates water resistance by holding a 1-inch height of water on a piece of paper with an area of ​​1 square meter for 60 or 600 seconds and measuring the weight of the absorbed water in grams.

[0036] The oil resistance test uses the TAPPI T-559 method, a 3M Kit test. It is a simple measurement method most commonly used for paper and cardboard, in which a numbered drop of oil is placed on the paper, the oil penetration state is observed after 15 seconds, and the maximum oil resistance point at which no oil penetration occurs is read and recorded.

[0037] The Hot Mazola Oil Test is used for high-temperature oil resistance testing. As a method to measure oil resistance at high temperatures, Mazola corn oil, which is widely used in practice, is poured into a water resistance test cob in a chamber maintained at 110°C, and after waiting for 2 minutes, the ratio of the area where the oil has penetrated into the paper is measured.

[0038] The heat resistance test uses the FUME Test. This method involves setting the air fryer temperature to 200°C, placing a paper sample in a tray, and operating it for 30 minutes to check for the generation of fumes, which are burnt residues on the paper.

[0039] The evaporation residue was calculated by conducting an experiment in accordance with the Food Code and measuring the amount of residue after eluting with 500 milliliters of a 4 percent acetic acid solution and evaporating the solution.

[0040] Glue adhesion is evaluated by using an OHP film with a thickness of 108 micrometers to uniformly apply glue to the surface of the paper, attaching the front and back surfaces of the paper, and then separating them after 1 minute to assess the degree of adhesion.

[0041] The present invention will be explained in more detail through the following examples.

[0042] Example 1:

[0043] This is the result of a laboratory test using a Meyer rod with 250g / m² of cup paper base paper (11).

[0044] In Comparative Example 1 with undercoating (12) An acrylic binder was used, and the coating amount was 8.2 g / m². The wet coating amount was 21 g / m², and the solid content of the coating liquid was 40.0 percent. Surface water resistance (surface Cobb) was 20 g H2O / m², and oil resistance (3M Kit) was 9.5. High-temperature oil resistance (Mazola Oil) was 100 percent, and the evaporation residue (acetic acid) was 4 percent, which was 15 ppm. The dissociation rate (coating paper recycling) was 95 percent, and full bonding performance was good. Fume generation occurred in the air fryer.

[0045] In Comparative Example 2 with undercoating (12) A fluorine-based binder was used, and the coating amount was 0.15 g / m². The wet coating amount was 11 g / m², and the solid content of the coating liquid was 1.4 percent. Surface water resistance (surface Cobb) was 12 g H₂O / m², and oil resistance (3M Kit) was 10.5. High-temperature oil resistance (Mazola Oil) was 2.2 percent, and the acetic acid residue (evaporation residue) was 4 percent at 7 ppm. The dissociation rate (coating paper recycling) was 98 percent, and full bonding performance was good. No fume generation occurred.

[0046] In Comparative Example 3 with undercoating (12)A silicone binder was used, and the coating amount was 1.8 g / m². The wet coating amount was 5 g / m², and the solid content of the coating liquid was 40.0 percent. Surface water resistance (surface Cobb) was 8 g H2O / m², and oil resistance (3M Kit) was 11. High-temperature oil resistance (Mazola Oil) was 3.4 percent, and the evaporation residue (acetic acid) was 4 percent, at 12 ppm. The dissociation rate (coating paper recycling) was 46 percent, and full bonding performance was poor. There was no fume generation.

[0047] In Example 1, a starch binder was used as the undercoating (12), and the coating amount was 8.6 g / m². The wet coating amount was 57 g / m², and the solid content of the coating liquid was 15.0 percent. The surface water resistance was 64 g H2O / m², and the oil resistance was 6. The high-temperature oil resistance was 12 percent, and the acetic acid evaporation residue was 4 percent, which was 42 ppm. The dissociation rate of the coating paper recycling was 89 percent, and the adhesive bonding was good. There was no fume generation.

[0048] In Example 2, a pigment binder was used for the undercoating (12), and the coating amount was 18.3 g / m². The wet coating amount was 28 g / m², and the solid content of the coating liquid was 65.0 percent. An oil-resistant starch binder was used for the top coating (13), and the coating amount was 4.5 g / m². The wet coating amount was 30 g / m², and the solid content of the coating liquid was 15 percent. The surface water resistance was 102 g H2O / m², and the oil resistance was 3M Kit. The high-temperature oil resistance was Mazola Oil, which failed, and the acetic acid residue was 4 percent, which was 64 ppm. The dissociation rate of the coating paper recycling was 94 percent, and the full bonding performance was good. There was no fume generation.

[0049] In Example 3, a pigment binder was used for the undercoating (12), and the coating amount was 18.3 g / m². The wet coating amount was 28 g / m², and the solid content of the coating liquid was 65.0 percent. An oil-resistant starch binder was used for the top coating (13), and the coating amount was 4.5 g / m². The wet coating amount was 30 g / m², and the solid content of the coating liquid was 15 percent. The surface water resistance (surface coating) was 21 g H₂O / m², and the oil resistance (3M Kit) was 9.5. The high-temperature oil resistance (Mazola Oil) was 6.4 percent, and the acetic acid (evaporation residue) was 4 percent, which was 66 ppm. The dissociation rate of the coating paper recycling was 90 percent, and the adhesive bonding was good. There was no fume generation.

[0050] In Example 1, Jungwon Chemical's DH-3000 was used as the acrylic oil-resistant agent, and in Example 2, a mixture of Japan's Asahi Guard AG-060 and ethanol was used as the fluorine-based agent, and SilForce SM3628 was used as the silicone for the test. In Example 3, Ingredion's Filmkote 2030 was used as the oil-resistant starch.

[0051] As shown in the comparative example, in the case of acrylic oil-resistant agents, as shown in Figure 3, it was confirmed that smoke was generated at high temperatures and the color changed as the oil-resistant agent deformed.

[0052] Comparative Examples 2 and 3, the fluorine-based and silicone types, showed no specific issues at high temperatures as oil-resistant papers; however, it was confirmed that those utilizing starch and pigments also withstood high temperatures. This is inferred to be due to the characteristics of natural compounds. In the case of oil-resistant starch, despite a large coating amount, it exhibited low water resistance and penetration into the paper substrate, resulting in low oil resistance; thus, it was confirmed that it is difficult to use immediately and requires additives to improve its physical properties. Furthermore, it was confirmed that there is a weakness in productivity because the low concentration of the coating solution and the high required coating amount result in a high drying load, requiring a significant amount of energy for drying in actual field use, and the speed cannot be increased if there are limitations in the dryer.

[0053] Example 2:

[0054] Changes in physical properties due to changes in undercoating (12) were confirmed.

[0055] In Example 4, clay was used as the main pigment for the undercoating (12), and styrene-butadiene was used as the binder. The solid content was 64.8 percent, the wet coating amount was 24.6 g / m², and the solid coating amount was 16 g / m². The main binder of the top coating (13) was starch, the water-resistant additive alkyl ketene dimer was 1.50 percent, and the starch curing agent was 1.00 percent. The solid coating amount was 4.6 g / m², the solid content was 15 percent, and the wet coating amount was 30.7 g / m². The surface water resistance surface Cove was 23 g H2O / m², and the surface oil resistance surface 3M Kit was 10. The high-temperature oil resistance Mazola Oil was 6 percent, and the evaporation residue acetic acid was 4 percent, which was 12 ppm. The dissociation rate of the coating paper recycling was 96 percent, and the glue bonding properties were good. There was no heat fume generation.

[0056] In Example 5, polyvinyl alcohol was used as the main pigment for the undercoating (12), and styrene butadiene was used as the binder. The solid content was 15 percent, the wet coating amount was 40 g / m², and the solid coating amount was 6 g / m². The main binder of the top coating (13) was starch, the water-resistant additive alkyl ketene dimer was 1.50 percent, and the starch curing agent was 1.00 percent. The solid coating amount was 4.4 g / m², the solid content was 15 percent, and the wet coating amount was 29.3 g / m². The surface water resistance surface Cobb was 26 g H2O / m², and the surface oil resistance surface 3M Kit was 10. The high-temperature oil resistance Mazola Oil was 12 percent, and the evaporation residue acetic acid was 4 percent, which was 64 ppm. The dissociation rate of the coating paper recycling was 86 percent, and the glue adhesion was average. There was no heat fume generation.

[0057] In Example 6, calcined clay was used as the main pigment for the undercoating (12), and styrene butadiene was used as the binder. The solid content was 49.8 percent, the wet coating amount was 36.1 g / m², and the solid coating amount was 18 g / m². The main binder of the top coating (13) was starch, the water-resistant additive alkyl ketene dimer was 1.50 percent, and the starch curing agent was 1.00 percent. The solid coating amount was 4.9 g / m², the solid content was 15 percent, and the wet coating amount was 32.7 g / m². The surface water resistance surface cob was 32 g H2O / m², and the surface oil resistance surface 3M Kit was 9.5. The high-temperature oil resistance Mazola Oil was 11 percent, and the evaporation residue acetic acid was 4 percent, which was 9 ppm. The dissociation rate of the coated paper recycling was 96 percent, and the adhesive bonding was good. There was no heat fume generation.

[0058] In Example 7, talc was used as the main pigment of the undercoating (12) and styrene butadiene was used as the binder. The solid content was 55.1 percent, the wet coating amount was 21.8 g / m², and the solid coating amount was 12 g / m². The main binder of the top coating (13) was starch, the water-resistant additive alkyl ketene dimer was 1.50 percent, and the starch curing agent was 1.00 percent. The solid coating amount was 4.1 g / m², the solid content was 15 percent, and the wet coating amount was 27.3 g / m². The surface water resistance surface Cove was 26 g H2O / m², and the surface oil resistance surface 3M Kit was 10. The high-temperature oil resistance Mazola Oil was 9 percent, and the evaporation residue acetic acid was 4 percent, which was 14 ppm. The dissociation rate of the coating paper recycling was 91 percent, and the glue bonding properties were good. There was no heat fume generation.

[0059] In Example 8, GCC 95, a calcium carbonate, was used as the main pigment of the undercoating (12), and styrene acrylic was used as the binder. The solid content was 64.9 percent, the wet coating amount was 35.4 g / m², and the solid coating amount was 23 g / m². The main binder of the top coating (13) was starch, the water-resistant additive alkyl ketene dimer was 1.50 percent, and the starch curing agent was 1.00 percent. The solid coating amount was 4.5 g / m², the solid content was 15 percent, and the wet coating amount was 30 g / m². The surface water resistance surface cove was 23 g H2O / m², and the surface oil resistance surface 3M Kit was 10. The high-temperature oil resistance Mazola Oil was 13 percent, and the evaporation residue acetic acid was 4 percent, which was 22 ppm. The dissociation rate of the coated paper recycling was 91 percent, and the adhesive bonding was good. There was no heat fume generation.

[0060] In Example 9, GCC 95, a calcium carbonate, was used as the main pigment of the undercoating (12), and styrene-butadiene was used as the binder. The solid content was 65.1 percent, the wet coating amount was 35.4 g / m², and the solid coating amount was 23 g / m². The main binder of the top coating (13) was starch, the water-resistant additive alkyl ketene dimer was 1.50 percent, and the starch curing agent was 1.00 percent. The solid coating amount was 4.6 g / m², the solid content was 15 percent, and the wet coating amount was 30.7 g / m². The surface water-resistant surface coating was 23 g H2O / m², and the surface oil resistance was 10. The high-temperature oil resistance was 13 percent, and the evaporation residue, acetic acid, was 4 percent, which was 159 ppm. The disintegration rate of the coated paper recycling was 98 percent, and the adhesive bonding was good. There was no heat fume generation.

[0061] In the case of the undercoating (12), it was confirmed that the final physical properties were not affected by various formulations, and there were no major problems even when using clay, calcined clay, talc, calcium carbonate, etc. However, as shown in Example 9, when using calcium carbonate, there is a problem of dissolving and leaching out in the acetic acid used for evaporation residue inspection, so as calcium carbonate can dissolve and leach out, as shown in Example 8, it is possible to address this by changing to a product with increased acid resistance in styrene butadiene latex or changing to styrene acrylic latex to suppress leaching as much as possible and increasing the binder content.

[0062] Example 3:

[0063] Changes in physical properties were confirmed when the composition of the top coating (13) was changed.

[0064] As a result of checking the effect of the coating amount, when styrene butadiene latex coating amount of 15 g / m² was used for the undercoating (12) and 3.5 g / m² was used for the topcoating (13) with 1.5 percent additive, the surface coating was 23 g H2O / m², 3M Kit was 9.5 percent, Mazola Oil was 9 percent, acetic acid was 4 percent was 13 ppm, the dissociation rate was 98 percent, the adhesive bonding was good, there was no fume generation, and no cracks occurred.

[0065] When styrene-butadiene latex was applied in an amount of 15 g / m² for the undercoating (12) and 5.5 g / m² was applied with 1.5 percent additive for the topcoating (13), the surface coating was 20 g H2O / m², 3M Kit was 10, Mazola Oil was 5 percent, acetic acid was 4 percent, and the dissociation rate was 91 percent, the adhesive bonding was good, there was no fume generation, and no cracks occurred.

[0066] When styrene-butadiene latex was applied in an amount of 15 g / m² for the undercoating (12) and 7.5 g / m² with 1.5 percent additive was applied for the topcoating (13), the surface coating was 12 g H2O / m², the 3M Kit was 11 percent, the Mazola Oil was 1 percent, the acetic acid was 4 percent, the dissociation rate was 85 percent, the adhesive bonding was average, there was no fume generation, and no cracks occurred.

[0067] When styrene-butadiene latex was applied in an amount of 15 g / m² for the undercoating (12) and 10.5 g / m² with 1.5 percent additive was applied for the topcoating (13), the surface coating was 80 g H2O / m², the 3M Kit was 3, the Mazola Oil failed, the acetic acid was 4 percent 67 ppm, the dissociation rate was 80 percent, the adhesive bonding was poor, there was no fume generation, and cracks occurred.

[0068] As a result of checking the effect of the curing agent, when styrene butadiene latex was applied in an amount of 15 g / m² for the undercoating (12) and 3.5 g / m² was applied with 0.5 percent of the curing agent for the top coating (13), the surface coating was 23 g H2O / m², 3M Kit was 9.5 percent, Mazola Oil was 9 percent, acetic acid was 4 percent was 17 ppm, the dissociation rate was 98 percent, the adhesive bonding was good, there was no fume generation, and no cracks occurred.

[0069] When styrene-butadiene latex was applied in an amount of 15 g / m² for the undercoating (12) and 5.5 g / m² was applied with 1.0 percent of a hardener for the topcoating (13), the surface coating was 20 g H2O / m², 3M Kit was 10, Mazola Oil was 5 percent, acetic acid was 4 percent, and the dissociation rate was 91 percent, the adhesive bonding was good, there was no fume generation, and no cracks occurred.

[0070] When styrene-butadiene latex was applied in an amount of 15 g / m² for the undercoating (12) and 7.5 g / m² was applied with 1.5 percent of a hardener for the topcoating (13), the surface coating was 12 g H2O / m², 3M Kit was 11, Mazola Oil was 1 percent, acetic acid was 4 percent, and the dissociation rate was 85 percent, the adhesive bonding was average, there was no fume generation, and no cracks occurred.

[0071] When styrene-butadiene latex was applied in an amount of 15 g / m² for the undercoating (12) and 10.5 g / m² was applied with 2.0 percent of a hardener for the topcoating (13), the surface coating was 80 g H2O / m², 3M Kit was 3, Mazola Oil failed, acetic acid 4 percent was 54 ppm, the dissociation rate was 80 percent, the adhesive bonding was poor, no fume was generated, and cracks occurred.

[0072] In the case of Example 3, the pigment used in the undercoating (12) was fixed with calcined clay, and the oil-resistant modified starch in the top coating (13) was fixed with Ingredion Filmkote 2030, and the change was confirmed by varying the additives and the amount of coating. The change in the state of the top coating (13) was confirmed by changing the weight of the additives, alkyl ketene dimer and starch hardener, together.

[0073] It was observed that when the amount of hardener added increases, the coating layer hardens and cracks form on the surface during processing after paper coating. At the same time, it was observed that even when the amount of coating increased, cracks formed in the coating layer, and the material penetrated into the paper and easily leached out. However, this can be adjusted depending on the type of starch and the ratio of amylopectin used in the top coating (13).

[0074] Example 4:

[0075] Top coating (13) optimization was performed.

[0076] In Example 10, for the undercoating (12), calcined clay was used as the pigment and styrene-butadiene latex was used in a weight ratio of 15, with a coating amount of 17.6 g / m². For the top coating (13), 100% oil-resistant modified starch, 1.50 percent additives, and a coating amount of 5.5 g / m² were used. The surface water resistance of the surface coating was 23 g H2O / m², and the surface oil resistance of the surface 3M Kit was 9.5. The high-temperature oil resistance of Mazola Oil was 9 percent, and the acetic acid evaporation residue was 4 percent, which was 13 ppm. The dissociation rate of the coated paper recycling was 98 percent, and the adhesive bonding performance was good. There was no heat fume generation.

[0077] In Example 11, for the undercoating (12), calcined clay was used as the pigment and styrene-butadiene latex was used in a weight ratio of 15, with a coating amount of 18.3 g / m². For the top coating (13), 50% oil-resistant modified starch, 50% polyvinyl alcohol, 1.50% additives, and a coating amount of 7.6 g / m² were used. The surface water resistance of the surface coating was 19 g H₂O / m², and the surface oil resistance of the surface 3M Kit was 10. The high-temperature oil resistance of Mazola Oil was 11%, and the acetic acid evaporation residue was 4%, which was 16 ppm. The dissociation rate of the coated paper recycling was 94 percent, and the adhesive bonding performance was good. There was no heat fume generation.

[0078] In Example 12, for the undercoating (12), calcined clay was used as the pigment and styrene-butadiene latex was used in a weight ratio of 15, with a coating amount of 15.7 g / m². For the top coating (13), 40% oil-resistant modified starch, 30% polyvinyl alcohol, 30% modified dextrin, 1.50% additives, and a coating amount of 6.4 g / m² were used. The surface water resistance of the surface Cobb was 32 g H2O / m², and the surface oil resistance of the 3M Kit was 10.5. The high-temperature oil resistance of Mazola Oil was 6%, and the acetic acid evaporation residue was 4%, which was 21 ppm. The dissociation rate of the coated paper recycling was 98 percent, and the adhesive bonding performance was good. There was no heat fume generation.

[0079] In Example 13, for the undercoating (12), calcined clay was used as the pigment and styrene-butadiene latex was used in a weight ratio of 15, with a coating amount of 21.4 g / m². For the top coating (13), modified dextrin 90, hydroxypropyl methylcellulose 10, additive 1.50 percent, and a coating amount of 4.9 g / m² were used. The surface water resistance of the surface Cobb was 37 g H2O / m², and the surface oil resistance of the 3M Kit was 10.5. The high-temperature oil resistance of Mazola Oil was 7 percent, and the evaporation residue of acetic acid was 4 percent, which was 17 ppm. The dissociation rate of the coated paper recycling was 96 percent, and the adhesive bonding performance was good. There was no heat fume generation.

[0080] In the top coating (13) formulation, the oil-resistant modified starch was tested using Ingredion Filmkote 2030, and the polyvinyl alcohol used was a Chinese product from Wanwei, grade 17-99, with a degree of polymerization of 1700 and a saponification rate of 99 percent. The modified dextrin was STABILYS BA 25, a mixed product of Octenyl Succinic Anhydride esterified maltodextrin and starch manufactured by Roquette. It is a representative alkylated dextrin that strengthens the oil-resistant emulsion film formation function by introducing lipophilic octenyl succinic acid side chains to a hydrophilic dextrin backbone. In the case of this product, if used alone, fine cracks may occur and the coating layer may break. To compensate for this, polyvinyl alcohol or hydroxypropyl methylcellulose was utilized to form a coating layer with water retention and a perfect finish. In this case, there is an advantage in that oil resistance can be secured even without using oil-resistant starch.

[0081] Example 5:

[0082] This shows the results of the coating test. This is the result of conducting a production test using the production equipment shown in Figure 2.

[0083] In the acrylic type, 100 parts by weight of Pigment-1 clay, 100 parts by weight of binder, and a coating amount of 6.8 g / m² were used for the undercoating (12). The top coating (13) was not used. 100 parts of starch and 0.7 parts of alkyl ketene dimer were used for the back coating (14). The surface water resistance was 20 g H2O / m², and the surface oil resistance was 9.5. The high-temperature oil resistance was 15 percent for Mazola Oil, and the evaporation residue was 4 percent for acetic acid, which was 19 ppm. The dissociation rate of the coated paper recycling was 93 percent, and the adhesive bonding was good. There was fume generation. Workability was the same as the existing one.

[0084] In the conventional fluorine-based coating, 100 parts by weight of Pigment-1 clay, 100 parts by weight of binder, and a coating amount of 0.3 g / m² were used for the undercoating (12). The top coating (13) was not used. 100 parts of starch and 0.7 parts of alkyl ketene dimer were used for the back coating (14). The surface water resistance was 21 g H2O / m², and the surface oil resistance was 10.5. The high-temperature oil resistance was 12 percent for Mazola Oil, and the acetic acid evaporation residue was 4 percent, which was 11 ppm. The dissociation rate of the coated paper recycling was 91 percent, and the adhesive bonding was good. There was no fume generation. Workability was the same as the conventional one.

[0085] In Example 14, 100 parts by weight of clay, which is Pigment-1, and styrene-butadiene, which is a binder, were used as the undercoating (12), with an application amount of 17 g / m². For the top coating (13), 100 parts of oil-resistant starch, 1.5 parts of alkyl ketene dimer, which is a water-resistant chemical, and 1 part of a starch curing agent were used, with an application amount of 5.5 g / m². For the back coating (14), 100 parts of starch and 0.7 parts of alkyl ketene dimer were used. The surface water resistance of the surface coating was 124 g H2O / m², and the surface oil resistance of the surface 3M Kit was 10.5. The high-temperature oil resistance of Mazola Oil was 22 percent, and the acetic acid evaporation residue was 4 percent, which was 16 ppm. The dissociation rate of the coated paper recycling was 95 percent, and the adhesive bonding performance was good. There was no fume generation. Workability was good.

[0086] In Example 15, 100 parts by weight of pigment-2 calcined clay, 13 parts by weight of styrene butadiene as a binder, and a coating amount of 24 g / m² were used for the undercoating (12). For the top coating (13), 30 parts of polyvinyl alcohol, 50 parts of dextrin, 20 parts of hydroxypropyl methylcellulose, 1.5 parts of alkyl ketene dimer as a water-resistant agent, 1.5 parts of a starch curing agent, and a coating amount of 5.6 g / m² were used. For the back coating (14), 100 parts of starch and 0.7 parts of alkyl ketene dimer were used. The surface water resistance of the surface coating was 22 g H2O / m², and the surface oil resistance of the surface 3M Kit was 8.5. The high-temperature oil resistance of Mazola Oil was 24 percent, and the acetic acid as an evaporation residue was 4 percent, which was 22 ppm. The dissociation rate of the coated paper recycling was 86 percent, and the adhesive bonding was good. There was no fume generation. Workability was good.

[0087] In Example 16, 0 parts by weight of calcined clay (pigment-2) and 30 parts by weight of calcium carbonate (pigment-3) were used as the undercoating (12), 13 parts by weight of styrene butadiene as the binder, and a coating amount of 16 g / m² were used. As the top coating (13), 40 parts of oil-resistant starch, 30 parts of polyvinyl alcohol, 30 parts of dextrin, 1.5 parts of alkyl ketene dimer as a water-resistant agent, 1 part of starch curing agent, and a coating amount of 5.5 g / m² were used. As the back coating (14), 100 parts of starch and 0.7 parts of alkyl ketene dimer were used. The surface water resistance of the surface coating was 22 g H2O / m², and the surface oil resistance of the surface 3M Kit was 9.5. The high-temperature oil resistance of Mazola Oil was 24 percent, and the evaporation residue of acetic acid was 4 percent, which was 23 ppm. The disintegration rate of the coated paper recycling was 92 percent, and the adhesive bonding was good. There was no fume generation. Workability was good.

[0088] In Example 17, 0 parts by weight of calcined clay (pigment-2) and 70 parts by weight of calcium carbonate (pigment-3) were used as the undercoating (12), 15 parts by weight of styrene acrylic as the binder, and an application amount of 12 g / m² were used. As the top coating (13), 90 parts of dextrin, 10 parts of hydroxypropyl methylcellulose, 2.5 parts of alkyl ketene dimer as a water-resistant agent, 1 part of starch hardener, and an application amount of 5.6 g / m² were used. As the back coating (14), 100 parts of starch and 0.7 parts of alkyl ketene dimer were used. The surface water resistance of the surface coating was 22 g H2O / m², and the surface oil resistance of the surface 3M Kit was 10.4. The high-temperature oil resistance of Mazola Oil was 24 percent, and the evaporation residue of acetic acid was 4 percent, which was 28 ppm. The dissociation rate of the coated paper recycling was 89 percent, and the adhesive bonding was good. There was no fume generation. Workability was good.

[0089] During actual production, the same base paper (11) was used to verify the results on-site. As a result of the field test, it was confirmed that overall stable resistance to induction and heat resistance was secured. Explanation of the symbols

[0090] 1 : Chemical transfer roll 2: Dryer Chamber 3 : Metering unit 4 : Backing Roll

Claims

Claim 1 A heat-resistant and oil-resistant food tray paper comprising: a base paper; an undercoating layer formed on the upper surface of the base paper and comprising a pigment and a binder; a top coating layer formed on the upper surface of the undercoating layer and comprising oil-resistant modified starch, an alkyl ketene dimer, and a starch curing agent; and a back coating layer formed on the lower rear surface of the base paper and comprising starch and an alkyl ketene dimer, wherein the undercoating layer forms a barrier that prevents the oil-resistant modified starch of the top coating layer from penetrating into the base paper, thereby causing the top coating layer to remain on the surface, wherein the top coating layer is configured to exhibit heat resistance and oil resistance under high temperature conditions of 180°C to 200°C, wherein the alkyl ketene dimer of the back coating layer is included in an amount of 0.5 to 2.5 weight percent relative to 100 weight parts of the starch, and wherein the back coating layer is configured to ensure water resistance that prevents wetting caused by condensation during refrigerated or frozen storage.

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