Food packaging sheets, coatings for food packaging sheets, food packaging containers

Abstract

To provide a food packaging sheet that is excellent in oil resistance and blocking resistance, as well as excellent in food release properties and low gloss. [Solution] A food packaging sheet comprising a coating layer arranged on a substrate, wherein the coating layer has endothermic peaks measured by a differential scanning calorimeter within the ranges of 40°C to 80°C and 100°C to 150°C. Preferably, the coating layer contains wax particles (A1), and the surface of the coating layer has 830 to 17,000 protrusions / mm² with a diameter of 3 μm to 13 μm, originating from the wax particles (A1). 2 The food packaging sheet having the aforementioned.

Description

[Technical Field]

[0001] The present invention relates to a food packaging sheet, a coating agent, and a food packaging container that exhibit excellent oil resistance and peelability to various foods, and suppress blocking between coated materials and gloss derived from resin films. [Background technology]

[0002] Traditionally, laminated sheets, made by laminating a resin film onto a paper base material, have been used for food packaging sheets and containers to prevent oil stains from food-derived oil components and to prevent food from sticking. However, in recent years, efforts to reduce environmental impact have attracted global attention, and efforts are being made to reduce the amount of plastic used and to design recyclable products. Accordingly, in the field of food packaging sheets and containers, there is active development of paper-coated food packaging sheets that are easy to recycle and reduce the amount of plastic used, by forming a coating film by applying a coating agent to a paper base material. As an example of such packaging sheets, Patent Document 1 describes how the durability against various foods is enhanced by adding an appropriate amount of wax.

[0003] However, the packaging sheet disclosed in Patent Document 1 had a problem in that it was somewhat poor at releasing foods that tend to stick to the packaging sheet, such as cheese. Also, in the recent market, when it comes to food packaging sheets that use paper as a base material, there is a demand for food packaging sheets that can be felt as paper, and food packaging sheets with a strong gloss derived from resins, etc., tend to be avoided because they appear to have a poor texture. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2018-16769 [Overview of the project] [Problems that the invention aims to solve]

[0005] The problem that this invention aims to solve is to provide a food packaging sheet, a coating agent for food packaging sheets, and a food packaging container that have excellent oil resistance and blocking resistance, as well as excellent food release properties and low gloss. [Means for solving the problem]

[0006] The inventors of this invention have diligently conducted research to solve the above-mentioned problems, and as a result, have arrived at this invention. In other words, the present invention relates to a food packaging sheet having a coating layer arranged on a substrate, wherein the coating layer has endothermic peaks measured by a differential scanning calorimeter within the ranges of 40°C to 80°C and 100°C to 150°C.

[0007] Furthermore, the present invention provides that the coating layer contains wax particles (A1), and the surface of the coating layer has 830 to 17,000 protrusions / mm² with a diameter of 3 μm to 13 μm. 2 Regarding the above-mentioned food packaging sheets.

[0008] Furthermore, the present invention relates to the food packaging sheet in which the wax particles (A1) have a melting point in the range of 100°C to 150°C.

[0009] Furthermore, the present invention relates to the food packaging sheet described above, wherein the coating layer comprises a resin having constituent units derived from alkyl (meth)acrylate monomers and / or styrene monomers.

[0010] Furthermore, the present invention relates to a coating agent for food packaging sheets comprising at least wax particles (A1) having a melting point of 100°C or more and 150°C or less, and wax particles (A2) having a melting point of 40°C or more and 80°C or less.

[0011] Furthermore, the present invention defines a particle diameter D such that the cumulative frequency from the small particle diameter side is 50% in the volume-based cumulative particle diameter distribution. 50 In this case, the D of the wax particles (A1) 50It relates to the coating agent for food packaging sheets that is 3 μm or more and 11 μm or less.

[0012] The present invention also relates to a food packaging container provided with a coating layer having endothermic peaks measured by a differential scanning calorimeter within the ranges of 40°C or more and 80°C or less and 100°C or more and 150°C or less, respectively.

Effect of the Invention

[0013] According to the present invention, in addition to being excellent in oil resistance and blocking resistance, it has excellent peelability of food, and it has become possible to provide a food packaging sheet with low gloss, a coating agent for food packaging sheets, and a food packaging container.

Mode for Carrying Out the Invention

[0014] Hereinafter, the present invention will be described in detail. Prior to the description of the present invention, first, terms, symbols, etc. used in this specification will be described. A numerical range specified using "~" includes the numerical values described before and after "~" as the lower limit value and the upper limit value. When expressed as "(meth)acryl", "(meth)acrylo", "(meth)acrylic acid", "(meth)acrylate", and "(meth)acryloyloxy", unless otherwise specified, they represent "acryl or methacryl", "acrylo or methacrylo", "acrylic acid or methacrylic acid", "acrylate or methacrylate", and "acryloyloxy or methacryloyloxy", respectively. "Monomer" and "monomer" are synonymous. The particle diameter at which the cumulative frequency from the small particle diameter side in the volume-based cumulative particle size distribution becomes 50% is abbreviated as D 50 For simplicity. "Coating agent for food packaging sheets" may be abbreviated as "coating agent". Unless otherwise specified, each of the various components used in this specification is interpreted to be independently usable alone or in combination of two or more.

[0015] <Coating Agent for Food Packaging Sheets> The coating agent of the present invention contains at least wax particles (A1) having a melting point of 100°C or higher and 150°C or lower, and wax particles (A2) having a melting point of 40°C or higher and 80°C or lower. In addition, the melting point of the wax particles in this specification is defined as the temperature at the peak of the endothermic peak measured by a differential scanning calorimeter (DSC).

[0016] Examples of the material of the wax particles (A1) include polyethylene wax, oxidized polyethylene wax, modified polyethylene wax, polypropylene wax, oxidized polypropylene wax, modified polypropylene wax, and the like.

[0017] The presence of the wax particles (A1) in the coating layer is considered to form irregularities on the surface of the coating layer, contributing to an improvement in blocking resistance and a reduction in the gloss of the coating layer surface. The D 50 of the wax particles (A1) in the coating agent is preferably 3 μm or more and 11 μm or less.

[0018] Examples of the material of the wax particles (A2) include carnauba wax, beeswax, paraffin wax, modified paraffin wax, montan wax, ethylene vinyl acetate copolymer wax, microcrystalline wax, and the like.

[0019] The presence of the wax particles (A2) on the surface of the coating layer is considered to contribute to an improvement in the peelability with respect to various foods. The D 50 of the wax particles (A2) in the coating agent is preferably 0.1 μm or more and 1 μm or less.

[0020] The reason why the effects can be obtained by using these wax particles (A1) and wax particles (A2) in combination is not clear, but it is thought that the wax particles (A1) form convex portions on the surface of the coating layer and mainly contribute to an improvement in blocking resistance, and the wax particles (A2) mainly contribute to an improvement in peelability, and the presence of these two types of particles contributes to oil resistance and low gloss.

[0021] When preparing the coating agent, the wax particles may be added directly as powder, or as a dispersion of the wax particles. When adding the powder, it may be dispersed using a disperser or similar device as needed.

[0022] <Resin> The coating agent of the present invention preferably contains a resin. Examples of resins include acrylic resins, styrene-acrylic resins, and styrene resins. There are no particular restrictions as long as the resin does not impair the formation of the coating layer, but it is preferably in the form of resin particles, and more preferably in the form of core / shell type resin particles.

[0023] Preferably, the core / shell type resin particles are those in which resin particles consisting of acidic group-containing monomers are synthesized, then neutralized to form a shell portion that can dissolve in water, and then hydrophobic monomers are dropped into the shell portion to form a core portion. This method allows each component to be given functions that improve film-forming properties and coating hardness, thus enabling food packaging sheets to have both oil resistance and blocking resistance.

[0024] As for the synthesis method of the resin, known polymerization methods such as solution polymerization, emulsion polymerization, suspension polymerization, and bulk polymerization are possible. In the present invention, emulsion polymerization is preferred because it allows for easy acquisition of a resin dispersion with high molecular weight, low viscosity, and high solid content in an aqueous medium.

[0025] The resin preferably has structural units derived from alkyl (meth)acrylate monomers and / or styrene monomers. It is also preferable that it has structural units derived from acidic group-containing monomers.

[0026] <Alkyl (meth)acrylate monomer> Examples of alkyl (meth)acrylate monomers include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, pentyl (meth)acrylate, and iso-butyl (meth)acrylate. Examples include tert-butyl (meth)acrylate, pentyl (meth)acrylate, isoamyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, etc. Of these, methyl (meth)acrylate, n-butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate are preferred.

[0027] <Styrene monomer> Examples of styrene monomers include styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, m-methylstyrene, vinylnaphthalene, benzyl acrylate, benzyl methacrylate, phenoxyethyl acrylate, phenoxyethyl methacrylate, phenoxydiethylene glycol acrylate, phenoxydiethylene glycol methacrylate, phenoxytetraethylene glycol acrylate, phenoxytetraethylene glycol methacrylate, phenoxyhexaethylene glycol acrylate, phenoxyhexaethylene glycol methacrylate, phenyl acrylate, and phenyl methacrylate. Of these, styrene and α-methylstyrene are preferred.

[0028] <Acidic group-containing monomers> The monomers constituting the resin preferably further contain constituent units derived from acidic group-containing monomers. Examples of acidic group-containing monomers include (meth)acrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, citraconic acid, and cinnamic acid. Of these, (meth)acrylic acid is preferred.

[0029] <Food packaging sheets> The food packaging sheet of the present invention is characterized in that a coating layer is arranged on a base material and has endothermic peaks measured by a differential scanning calorimeter within the ranges of 40°C to 80°C and 100°C to 150°C. The inventors have found that by having these two endothermic peaks, the food packaging sheet can achieve excellent oil resistance, peelability, and blocking resistance, while also reducing the gloss of the coating layer.

[0030] When the coating layer is formed from the coating agent for food packaging sheets of the present invention, the above endothermic peaks are endothermic peaks originating from the melting points of wax particles (A1) and wax particles (A2), respectively.

[0031] The coating layer contains wax particles (A1), and the surface of the coating layer has 830 to 17,000 protrusions / mm² with a diameter of 3 μm to 13 μm, originating from the wax particles (A1). 2 It is preferable to have such protrusions. Having such protrusions on the surface of the coating layer is expected to further improve oil resistance, peelability, and blocking resistance, and to further reduce the gloss of the coating layer. In this specification, the diameter of the protrusions refers to the diameter of the major axis of the protrusions forming the protrusions on the surface of the coating layer. The protrusions on the surface of the coating layer were observed using a scanning electron microscope (SEM), and the number of protrusions within a diameter range of 3 to 13 μm was visually counted, and the obtained value was measured in mm². 2 It was calculated by converting it to the number of items per unit.

[0032] It is presumed that when there are 830 or more protrusions on the surface of the coating layer, originating from wax particles (A1) with a diameter of 3 μm to 13 μm, the amount of light diffusely reflected from the surface of the coating layer decreases, resulting in low gloss. Furthermore, if the coating layer contains resin, the contact area with the resin decreases, which is thought to improve blocking resistance.

[0033] When the surface of the coating layer has 17,000 or fewer protrusions with a diameter of 3 μm to 13 μm, originating from wax particles (A1), it is presumed that coating defects will be less likely to occur on the surface of the coating layer, and the surface area of ​​the coating layer will be appropriately reduced, thereby increasing oil resistance and peelability. Therefore, even if sticky foods such as cheese adhere to the coating layer, it is likely to peel off easily.

[0034] The coating layer preferably further contains a resin, and more preferably contains a resin having structural units derived from alkyl (meth)acrylate monomers and / or styrene monomers.

[0035] Preferably, the coating layer further contains wax particles (A2) with a melting point between 40°C and 80°C. The inclusion of wax particles (A2) further improves the release properties from various foods.

[0036] <Base material> Examples of substrates include porous sheets such as paper, nonwoven fabric, and woven fabric; plastic films such as polyethylene film, polypropylene film, polyester film, and nylon film; and metal foils such as aluminum foil. Furthermore, the substrate may consist of multiple layers formed by laminating the above substrates. From the viewpoint of wettability and environmental considerations, the substrate of the surface to which the coating agent is applied (also called coating or painting) is preferably paper.

[0037] <Coating method for coating agents> As coating methods of the coating agent on the base material, knife coater, comma coater, roll coater, bar coater, gravure coater, flexo coater, dipping, etc. can be mentioned. After coating the coating agent on the base material, it is preferable to form a coating layer by means such as heating as appropriate. Further, the coating agent may be applied in multiple layers as necessary, or may be applied to both sides of the base material.

Example

[0038] Hereinafter, the present invention will be specifically described with reference to examples. In the examples, unless otherwise specified, "parts" means "parts by mass", and "%" means "% by mass".

[0039] The addition amount of the wax in the present invention is expressed in phr. Phr represents the addition amount (% by mass) relative to 100% by mass of the resin (solid content).

[0040] <Measurement of melting point and glass transition temperature> The melting point and glass transition temperature (hereinafter sometimes abbreviated as "Tg") of the resin, wax particles (A1), and wax particles (A2) were measured using a DSC (differential scanning calorimeter, DSC2500 manufactured by TA Instruments). A 3 mg sample was precisely weighed and placed in an aluminum pan, and an empty (blank) aluminum pan as a reference was set in a DSC measurement holder, and measured under a temperature rising condition of 10 °C / min to obtain a DSC curve. In the obtained DSC curve, the temperature at the apex of the endothermic peak derived from melting was defined as the melting point. Further, the temperature at the intersection of the straight line obtained by extending the low-temperature side baseline to the high-temperature side and the tangent line drawn at the point where the curvature on the low-temperature side of the melting peak is maximum (extrapolated onset temperature of melting) was defined as Tg.

[0041] <Acid value> It was determined by potentiometric titration with a potassium hydroxide-ethanol solution based on the method described in JIS K2501.

[0042] <D 50 measurement> D of the resin, wax particles (A1), and wax particles (A2) 50These particles were each diluted 500 times with water, and approximately 5 ml of the diluted solution was measured using dynamic light scattering (the measuring device was NanoTrac UPA; manufactured by MicroTrac Bell). 50 The following was determined: In the volume-based cumulative particle size distribution obtained by measurement, the particle size at which the cumulative frequency from the small particle size side becomes 50% is D. 50 That's what I decided.

[0043] <Preparation of coating agent> [Example 1] 60.0 parts of butyl alcohol were charged into a reaction vessel (reaction tank) equipped with a stirrer, thermometer, dropping funnel, and reflux valve, and the internal temperature of the reaction vessel was raised to 110°C under a nitrogen atmosphere. Next, 40.0 parts of styrene, 30.0 parts of α-methylstyrene, and 30.0 parts of acrylic acid were charged into the dropping funnel as monomer (a-1), and then 5 parts of azoisobutyronitrile were added and dissolved, and the mixture was added dropwise over 2 hours. After the addition was complete, the reaction was carried out at 110°C for 4 hours. After the reaction, the mixture was cooled to 80°C, neutralized with 28.3 parts of 25% aqueous ammonia, diluted with 220.0 parts of water, and the butyl alcohol was removed by distillation to adjust the non-volatile content to 30% to obtain an aqueous solution of the polymer (shell portion). The Tg of the obtained polymer (shell portion) was 120°C. Next, the internal temperature of the reaction vessel was adjusted to 80°C, and 100 parts of water were added to the reaction vessel. Then, 94.0 parts of styrene and 100.0 parts of 2-ethylhexyl acrylate were added to a dropping funnel as monomers. The internal temperature of the reaction vessel was raised to 80°C, and under a nitrogen atmosphere, 17.0 parts of a 10% aqueous solution of ammonium persulfate was added. After 5 minutes, the monomer mixture from the dropping funnel was added dropwise over 2 hours to carry out the reaction. After the dropwise addition was complete, the reaction was continued for another 3 hours at 80°C to obtain resin 1. The Tg of the polymer (core) portion was -12°C, the average particle size of the resin was 85 nm, and the acid value of the nonvolatile content of the resin was 78 mg KOH / g. To the obtained resin 1, Chemipearl W410 (polyethylene wax manufactured by Mitsui Chemicals, Inc., nonvolatile content: 40%, melting point: 110°C, D) was added as wax particles (A1). 50 :9μm) 6phr and wax particles (A2) as AQUACER497 (BYK paraffin wax, 50% non-volatile content, melting point: 50℃, D 50A coating agent was prepared by adding a predetermined amount of (0.2 μm) and water to adjust the non-volatile content to 40%. The obtained coating agent was applied to one side of commercially available paper (weighing 60 g) using a bar coater #12. After coating, a food packaging sheet was obtained by drying in a hot air oven at 100°C for 60 seconds.

[0044] [Example 2] 35.9 parts of water were charged into a reaction vessel (reaction tank) equipped with a stirrer, thermometer, dropping tank, and reflux valve. Separately, 20.4 parts of 2-ethylhexyl acrylate, 19.2 parts of styrene, 0.4 parts of acrylic acid, 0.8 parts of Emal 0 (sodium lauryl sulfate, active ingredient 97% or more, manufactured by Kao Corporation), and 16.2 parts of water were pre-mixed and stirred to prepare an emulsion of ethylenically unsaturated monomers, which was then charged into the dropping tank. After raising the internal temperature of the reaction vessel to 80°C and thoroughly purging with nitrogen, 3.2 parts of a 5% aqueous solution of potassium persulfate was added as a polymerization initiator, and the emulsion of ethylenically unsaturated monomers was added dropwise from the dropping tank over 2 hours while maintaining the internal temperature at 80°C to carry out emulsion polymerization. After the dropwise addition was complete, the reaction was continued for a further 3 hours while maintaining the temperature at 80°C. Then it was cooled to 50°C and neutralized by adding 0.2 parts of 25% aqueous ammonia. Further water was added to adjust the non-volatile content concentration to 40.0% to obtain styrene-acrylic resin 2. The glass transition temperature (Tg) of resin 2 was 1°C. Chemipearl W410 (polyethylene wax manufactured by Mitsui Chemicals, Inc., non-volatile content: 40%, melting point: 110°C, D) was added to the obtained resin 2 as wax particles (A1). 50 :9μm) 6phr and wax particles (A2) as AQUACER497 (BYK paraffin wax, 50% non-volatile content, melting point: 50℃, D 50 A coating agent was prepared by adding a predetermined amount of (0.2 μm) and water to adjust the non-volatile content to 40%. The obtained coating agent was applied to one side of commercially available paper (weighing 60 g) using a bar coater #12. After coating, a food packaging sheet was obtained by drying in a hot air oven at 100°C for 60 seconds.

[0045] [Example 3] An aqueous dispersion of acrylic resin 3 was prepared in the same manner as in Example 2, except that the ethylenically unsaturated monomers were changed to 22.4 parts methyl methacrylate, 19.6 parts butyl acrylate, and 2.0 parts methacrylic acid, and a food packaging sheet was obtained. The Tg of resin 3 was 20°C.

[0046] [Examples 4-15, Comparative Examples 1-7] A coating agent was prepared in the same manner as in Example 1, except that the materials and amounts added were changed as listed in Table 1, and a food packaging sheet was obtained. In Table 1, V100 is listed within wax particles (A2) for convenience, but it is wax particles other than wax particles (A1) and (A2) as described below.

[0047] The raw materials listed in Table 1 are as follows: <Wax particles (A1)> ·A1-1: Chemipearl W410, manufactured by Mitsui Chemicals, polyethylene wax, melting point = 110℃, D 50 =9μm ·A1-2: Chemipearl W200, manufactured by Mitsui Chemicals, polyethylene wax, melting point = 110℃, D 50 = 6μm · A1-3: Micropro200, manufactured by MP Gokyo Food & Chemical Co., Ltd., modified polypropylene wax, melting point = 150℃, D 50 = 8μm A1-4: Chemipearl W308, manufactured by Mitsui Chemicals, polyethylene wax, melting point = 130℃, D 50 = 6μm A1-5: Chemipearl W400, manufactured by Mitsui Chemicals, polyethylene wax (melting point = 110℃, D 50 (=4μm)

[0048] <Wax particles (A2)> ·A2-1: AQUACER497, manufactured by BYK, paraffin wax, melting point = 55℃, D 50 = 0.2 μm • A2-2: AQUACER561, manufactured by BYK, beeswax wax, melting point = 65℃, D 50 = 0.8 μm A2-3: AQUACER541, manufactured by BYK, montane ester wax, melting point = 80°C, D 50 = 0.5 μm <Wax particles other than wax particles (A1) and (A2)> • V100: Chemipearl V100, manufactured by Mitsui Chemicals, ethylene vinyl acetate copolymer wax, melting point = 38℃, D 50 = 12 μm

[0049] Evaluation items and evaluation methods The evaluation items and evaluation methods for the coated sheets obtained in each example and comparative example are as follows.

[0050] <Endothermic peak temperature of food packaging sheets> The obtained food packaging sheets were impregnated with methyl ethyl ketone and left to stand at 25°C for 3 days. Subsequently, the methyl ethyl ketone extract eluted from the food packaging sheets was dried and solidified. The resulting solidified material was subjected to DSC measurement using the same method as the melting point measurement described above, and the temperature of the peak of the endothermic peak in the obtained DSC curve was recorded.

[0051] <Diameter and number of protrusions on the surface of the coating layer of food packaging sheets> The surface of the coating layer of the obtained food packaging sheet was observed using a scanning electron microscope (SEM, JEOL Corporation, JSM-6010PLUS / LV). Magnification: 1000x, Observation area: 12,000 μm² 2 Observations were made, and the diameter of the major axis forming the convex portion was defined as the diameter of the convex portion. For the observed convex portions, the number of convex portions within the diameter range of 3 to 13 μm was visually counted. The obtained values ​​were expressed in mm. 2 It was converted to the number of items per unit.

[0052] <Oil resistance of food packaging sheets> To evaluate the oil resistance of the obtained sheets, several drops of salad oil (canola oil, manufactured by Nisshin Oillio Co., Ltd.) heated to 80°C were dropped onto the coated surface (coated surface), and the state of staining on the surface of the coated layer and the state of seepage of the salad oil to the back of the sheet (the side of the sheet opposite the coated layer) were observed. [Evaluation Criteria] A: Even after 30 minutes since application, there is no staining or bleed-through (extremely good). B: After 30 minutes following application, staining is visible, but there is no bleed-through (good). C: No show-through was observed 10 minutes after application, but show-through occurred after 30 minutes (usable). D: Show-through occurred less than 10 minutes after application (unusable).

[0053] <Release properties of food packaging sheets> A slice of cheese was placed on the coated side (coated surface) of the food packaging sheet and heated in a microwave oven at 600W for 1 minute. The degree of adhesion of the cheese to the coated surface was observed immediately after heating. The slice of cheese used was Snow Brand Megmilk's "Torokeru Slice" (registered trademark). [Evaluation Criteria] A: The cheese slid off the coated surface simply by tilting the food packaging sheet 90° (extremely good). B: The food packaging sheet was tilted 90°, and the cheese slid off the coating with just one application of force using a spatula (good). C: The cheese didn't slide off easily, but I was able to completely remove it from the coated surface with a spatula (usable). D: The cheese could not be removed from the coated surface even with a spatula (unusable).

[0054] <Blocking resistance> After the obtained coated sheets are tightly packed together so that the coated surfaces are in contact with each other, 4 kgf / cm² is applied. 2 The samples were held under pressure for 24 hours in a 40°C, 80% RH (relative humidity) environment. The ease with which the adhered coated sheets could be peeled apart and the condition of the coated surface after peeling were observed. [Evaluation Criteria] A: The coated sheets were not sticking to each other (excellent condition). B: The coated sheets were stuck together, but they could be separated by applying force horizontally to the coated surface (good). C: The coated sheets were stuck together, and applying force horizontally to the coated surface did not allow them to be separated. However, applying force vertically allowed the coated sheets to be separated, and there was no damage to the coated surface (usable). D: The coated sheets were stuck together, and applying force perpendicular to them caused damage to the coated surface, or the coated sheets could not be separated (unusable).

[0055] <Glossiness of food packaging sheets> A coating layer was formed by applying a coating agent to a 50 μm thick polyethylene terephthalate (PET) film. The reflectance of the resulting coated surface was measured using a gloss meter (BYK micro-gloss gloss meter) at an incident angle of 60° and the reflectance was read. [Evaluation Criteria] A: Less than 70.0%. The glossiness derived from the resin film when light is shone on it is absent, and the texture of the paper base material remains both to the touch and visually (extremely good). B: 70.0% to less than 80.0%. There is no glossiness from the resin film when light is shone on it; the texture of the paper base material remains visible, but the tactile feel is smooth (good). C: 80.0% to less than 90.0%. When light is shone on it, a glossy appearance derived from the resin film is visible, and the texture is smooth to the touch, but the texture of the paper remains visible to the naked eye (usable). D: 90.0% or higher. The gloss derived from the resin film is strong when light is shone on it, and the texture derived from the resin film is clearly discernible both by touch and sight (unusable).

[0056] [Table 1]

[0057] From the above results, it has become clear that the food packaging sheet of the present invention has excellent oil resistance, release properties, and blocking resistance, as well as low gloss.

Claims

1. A food packaging sheet comprising a coating layer arranged on a substrate, wherein the coating layer has endothermic peaks measured by a differential scanning calorimeter within the ranges of 40°C to 80°C and 100°C to 150°C.

2. The coating layer contains wax particles (A1), and the surface of the coating layer has 830 to 17,000 protrusions / mm² with a diameter of 3 μm to 13 μm. 2 A food packaging sheet according to claim 1, having the characteristics of the food packaging sheet according to claim 1.

3. The food packaging sheet according to claim 2, wherein the wax particles (A1) have a melting point in the range of 100°C to 150°C.

4. The food packaging sheet according to claim 1, wherein the coating layer comprises a resin having structural units derived from alkyl (meth)acrylate monomers and / or styrene monomers.

5. A coating agent for food packaging sheets comprising at least wax particles (A1) having a melting point of 100°C or more and 150°C or less, and wax particles (A2) having a melting point of 40°C or more and 80°C or less.

6. In a volume-based cumulative particle size distribution, the particle size at which the cumulative frequency from the small particle size side accounts for 50% is defined as D. 50 In this case, the D of the wax particles (A1) 50 The coating agent for food packaging sheets according to claim 5, wherein the particle size is 3 μm or more and 11 μm or less.

7. A food packaging container comprising a coating layer having endothermic peaks, measured by a differential scanning calorimeter, within the ranges of 40°C to 80°C and 100°C to 150°C, respectively.

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