Greaseproof paper and packaging bags

Abstract

To provide oil resistant paper which is environmentally friendly and excellent in oil resistance and heat sealability, and a packaging bag having said oil resistant paper.SOLUTION: An oil-resistant paper according to one embodiment of the present invention is heat-sealable oil-resistant paper, which comprises a paper base material containing an oil-resistant agent and a heat-seal layer, with the paper base material laminated on one or both surfaces of the heat-seal layer, and a smoothness of the surface of the heat-seal layer measured according to JIS-P 8119 (1998) is 9 to 200 seconds.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to greaseproof paper and packaging bags. [Background technology]

[0002] Grease-resistant paper is widely used as packaging material for food products such as prepared dishes and fast food to prevent oil from seeping out from the packaged contents and staining the outer surface with oil.

[0003] In recent years, with changes in eating habits, grease-resistant paper laminated with resin films such as polyethylene and polyethylene terephthalate has been used for bags made by heat sealing, such as bags for take-out fried foods and packaging bags for microwave ovens (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2016-22957 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in laminated paper with a resin film laminated thereon, the surface on which the resin film is laminated has oil resistance, but there is a risk that oil resistance cannot be imparted to the surface on which the resin film is laminated, or to the inside or sides of the paper base material. In addition, if the contents to be packaged are humid, water droplets may accumulate in the package and adhere to the contents, causing the contents to become soft and deteriorating in quality. Furthermore, the laminated paper cannot be recycled as waste paper because the film remains, and there is a risk that it may lead to marine pollution as microplastics. Therefore, there is a demand for an environmentally friendly greaseproof paper that is excellent in oil resistance and heat sealability to replace laminated paper.

[0006] The present invention has been made in light of the above circumstances, and has an object to provide an grease-resistant paper that is environmentally friendly and has excellent oil resistance and heat sealability, and a packaging bag comprising the grease-resistant paper. [Means for solving the problem]

[0007] The grease-resistant paper according to an embodiment of the present invention is a grease-resistant paper having heat-sealing properties, and comprises a paper base material containing an grease-resistant agent and a heat-sealing layer, the paper base material having a heat-sealing layer laminated on one or both sides, and the smoothness of the surface of the heat-sealing layer, measured in accordance with JIS-P8119 (1998), is 9 seconds or more and 200 seconds or less. Effect of the Invention

[0008] According to the present invention, it is possible to provide greaseproof paper that is environmentally friendly and has excellent oil resistance and heat sealability. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] [Description of the embodiment of the present invention] The grease-resistant paper of one embodiment of the present invention is a grease-resistant paper having heat-sealing properties, comprising a paper base material containing an grease-resistant agent and a heat-sealing layer, the paper base material having a heat-sealing layer laminated on one or both sides, and the smoothness of the surface of the heat-sealing layer, measured in accordance with JIS-P8119 (1998), is 9 seconds or more and 200 seconds or less.

[0010] The grease-resistant paper has excellent oil resistance even inside and on the sides of the paper base material because the paper base material contains an oil-resistant agent. In addition, the smoothness of the surface of the heat-sealing layer is 9 seconds or more and 200 seconds or less, so that the blocking suppression effect between the heat-sealing layers can be improved. Therefore, the grease-resistant paper can provide grease-resistant paper with excellent oil resistance and heat-sealing properties. In addition, the grease-resistant paper is environmentally friendly because it does not use a resin film.

[0011] The greaseproof paper preferably has a surface smoothness of 8 to 30 seconds measured according to JIS-P8119 (1998) on the paper substrate on which the heat seal layer is laminated, which can further improve the effect of suppressing blocking between the heat seal layers.

[0012] The heat seal layer preferably contains an olefin resin as a main component, which allows the heat seal layer to exhibit heat seal strength not only at room temperature but also at low temperatures.

[0013] The main component of the oil-resistant agent is preferably a fluorine-based resin, an acrylic resin, a synthetic rubber latex, or a combination thereof. By the main component of the oil-resistant agent being a fluorine-based resin, an acrylic resin, or a synthetic rubber latex, the grease-resistant paper has good oil resistance.

[0014] The amount of the oil-proofing agent added is preferably 4.0 kg / t or more and 10.0 kg / t or less relative to the pulp fibers of the paper base material. When the amount of the oil-proofing agent added relative to the pulp fibers of the paper base material is within the above range, the oil resistance and the adhesion between the paper base material and the heat seal layer are excellent. "kg / t" refers to the amount added (kg) per ton of pulp fibers of the paper base material.

[0015] The moisture permeability of the greaseproof paper according to JIS-Z0208 (1976) is 600g / m 2 ·1500g / m for 24 hours or more 2 When the moisture permeability of the greaseproof paper is within the above range, moisture in the packaged contents is less likely to turn into water droplets and the humidity is kept at an appropriate level, so that the quality of the contents can be well maintained.

[0016] A packaging bag according to another embodiment of the present invention includes the grease-resistant paper. Since the packaging bag includes the grease-resistant paper, the packaging bag has excellent oil resistance and heat sealability.

[0017] [Details of the embodiment of the present invention] The present invention will be described in detail below. The following description of the components may be based on representative embodiments or specific examples, but the present invention is not limited to such embodiments. The greaseproof paper according to one embodiment of the present invention will be described in detail below. The amount of each material (bone-dry internal amount) added to the paper base material described below refers to the mass ratio relative to the bone-dry mass of the pulp of the paper base material, unless otherwise specified. Furthermore, the content of each material added to the composition for forming a heat-sealing layer refers to the bone-dry mass ratio of each material relative to the mass of the entire heat-sealing layer, unless otherwise specified.

[0018] <Oil-resistant paper> The greaseproof paper comprises a paper substrate and a heat seal layer on at least one surface of the paper substrate. The heat seal layer may be of single layer or multi-layer structure.

[0019] [Paper base material] The paper base material is obtained by papermaking a slurry containing raw pulp. The paper base material may be either a single layer or a multilayer. (Raw pulp) The paper base material is preferably made of raw pulp as a main component. Examples of the raw pulp that can be used to form the paper base material include virgin pulp, recycled pulp, and combinations of these pulps.

[0020] Examples of virgin pulp include chemical pulps such as bleached hardwood kraft pulp (LBKP), bleached softwood kraft pulp (NBKP), unbleached hardwood kraft pulp (LUKP), unbleached softwood kraft pulp (NUKP), semi-bleached hardwood kraft pulp (LSBKP), semi-bleached softwood kraft pulp (NSBKP), hardwood sulfite pulp, and softwood sulfite pulp; and pulps produced chemically or mechanically from mechanical pulps (MP) such as stone ground pulp (SGP), pressed stone ground pulp (TGP), chemi-ground pulp (CGP), groundwood pulp (GP), and thermomechanical pulp (TMP). These pulps may be used alone or in combination.

[0021] Examples of waste paper pulp that can be used include disintegrated waste paper pulp, disintegrated and deinked waste paper pulp (DIP), and disintegrated, deinked and bleached waste paper pulp, which are produced from, for example, brown waste paper, kraft envelope paper, magazine paper, newspaper paper, flyer paper, office paper, corrugated cardboard paper, white waste paper, Kent waste paper, imitation waste paper, and land certificate paper, and can be used alone or in combination.

[0022] (oil resistant agent) The oil-resistant agent may be one or more of the following compounds: fluorine-based resin, starch, cellulose derivative, gelatin, casein, soy protein, polyvinyl alcohol, polyisoprene, polymer or copolymer of chloroprene, polydiene, polyalkene, polymer or copolymer of vinyl monomer, synthetic rubber latex, polyurethane resin, polyester resin, polyamide resin, olefin-maleic anhydride resin, silicone resin, acrylic resin, melamine resin, vegetable wax, animal wax, mineral wax, petroleum wax, synthetic hydrocarbon wax, 12-hydroxystearic acid amide, stearic acid amide, phthalic anhydride imide, higher fatty acid amide or ester or ketone or ether of chlorinated hydrocarbon. Among the above-mentioned oil-resistant agents, from the viewpoint of oil resistance, it is preferable to add an oil-resistant agent mainly composed of acrylic resin, synthetic rubber latex, or fluorine-based resin, and fluorine-based resin is particularly preferable. By adding an oil-resistant agent whose main component is a fluororesin to the paper base material, this grease-resistant paper has excellent oil resistance even in the inside and sides of the paper base material with a small amount of added oil-resistant agent. It is presumed that the oil-resistant agent whose main component is a fluororesin is easily dispersed in the paper base material due to the high surface tension of the fluororesin, and is therefore able to exhibit oil resistance even with a small amount added.

[0023] Examples of the fluorine-based resin include anionic fluorine-based resins and cationic fluorine-based resins. Commercially available anionic fluorine-based oil-resistant agents include Asahi Guard (registered trademark) AG-E080 and AG-E090 manufactured by Asahi Glass Co., Ltd., Unidyne (registered trademark) TG-8111 and TG8731 manufactured by Daikin Industries, Ltd., and Solvera (registered trademark) PT5060 and PT5045 manufactured by Solvay. Commercially available cationic fluorine-based oil-resistant agents include Asahi Guard (registered trademark) AG-E060 and AG-E070 manufactured by Asahi Glass Co., Ltd., and CAPSTONE (registered trademark) P620 and P623 manufactured by DuPont. Among these, anionic fluorine-based resins are preferred from the viewpoint of obtaining oil resistance at a low addition amount.

[0024] The lower limit of the amount of the oil-proofing agent added is preferably 4.0 kg / t of the pulp fibers of the paper base material. The upper limit of the amount of the oil-proofing agent added is preferably 10.0 kg / t, more preferably 8.0 kg / t of the pulp fibers of the paper base material. By adding the amount of the oil-proofing agent to the pulp fibers of the paper base material within the above range, the oil resistance and the adhesion between the paper base material and the heat seal layer are excellent.

[0025] (Other additives) Other additives may be added to the paper base material as necessary, such as fillers, pigments, sizing agents, coagulants, oil-proofing agents, fluorescent whitening agents, aluminum sulfate, retention aids, drainage aids, dry strength agents, wet strength agents, coloring dyes, coloring pigments, water-resistant agents, etc., which may be used alone or in combination.

[0026] (Papermaking) The paper base material can be made by using a known papermaking machine to make a raw material slurry containing the above-mentioned raw material pulp and additives. If necessary, a calendering step can also be provided.

[0027] [Heat seal layer] The heat seal layer is formed by applying a composition for forming a heat seal layer to one or both sides of a paper substrate.

[0028] The heat seal layer preferably contains an olefin resin as a main component. Examples of the olefin resin include polyethylene resin and polypropylene resin. Examples of the polyethylene resin include low density polyethylene (LDPE), linear low density polyethylene (LLDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), ethylene acrylic acid copolymer (EAA), ethylene-methacrylic acid copolymer (EMAA), ethylene-ethyl acrylate copolymer (EEA), ethylene-methyl acrylate copolymer (EMA), ethylene-vinyl acetate copolymer (EVA), carboxylic acid modified polyethylene, ionomer, and derivatives thereof, and mixtures thereof. Examples of the polypropylene resin include polypropylene (PP) homopolymer, random polypropylene (random PP), block polypropylene (block PP), chlorinated polypropylene, carboxylic acid modified polypropylene, and derivatives thereof, and mixtures thereof. Among these, ethylene acrylic acid copolymer is more preferable from the viewpoint of heat sealability in a low temperature range of about 100 to 130°C.

[0029] The lower limit of the content of the olefin resin relative to the total solid content of the heat seal layer is 50.0% by mass, preferably 90.0% by mass. If the content of the olefin resin is less than 50.0% by mass, sufficient heat sealability may not be obtained. On the other hand, the upper limit of the content of the olefin resin is 100.0% by mass, preferably 95.0% by mass.

[0030] (Other additives) The heat seal layer of the present invention may contain additives other than those mentioned above. Examples of the additives include water-soluble polymers, adhesives, inorganic pigments, organic pigments, sizing agents, viscosity modifiers, coloring dyes, coloring pigments, water-resistant agents, lubricants, and the like, which may be used alone or in combination.

[0031] [Properties of greaseproof paper] (Smoothness) The lower limit of the Beck smoothness of the surface of the heat seal layer measured in accordance with JIS-P8119 (1998) is 9 seconds, more preferably 15 seconds. The upper limit of the smoothness is 200 seconds, more preferably 150 seconds. If the smoothness is below the lower limit, the surface of the greaseproof paper becomes rough (the contact area becomes small), and the heat seal strength may decrease. If the smoothness exceeds the upper limit, the blocking suppression effect of the heat seal layer may decrease. By having the smoothness of the surface of the heat seal layer be 9 seconds or more and 200 seconds or less, the blocking suppression effect between the heat seal layers can be improved, and adhesion of the contents can be prevented.

[0032] The lower limit of the smoothness of the surface of the paper substrate on which the heat seal layer is laminated is preferably 5 seconds, more preferably 8 seconds. The upper limit of the smoothness is preferably 180 seconds, more preferably 30 seconds. If the smoothness is below the lower limit, the surface of the greaseproof paper becomes rough (there are many voids), and the heat seal layer coating liquid penetrates too much into the paper substrate, which may reduce the heat seal strength. If the smoothness exceeds the upper limit, the effect of suppressing blocking between the heat seal layers may decrease.

[0033] (Oil resistance) The lower limit of the kit value, which is an index of the oil resistance of the greaseproof paper, is preferably 5 or more, and more preferably 6 or more. If the kit value is less than 5, the paper may not function as an greaseproof paper. There is no particular upper limit to the kit value of the greaseproof paper. Here, the "kit value" refers to the oil resistance of the surface and cross section measured under conditions of 23°C and 50% humidity (JAPAN TAPPI No. 41 Paper and Paperboard - Oil Repellency Test Method - Kit Value by Kit Method), and the higher the value, the higher the oil resistance.

[0034] (moisture permeability) The moisture permeability of the greaseproof paper is measured under condition B in accordance with JIS-Z0208

[1976] Moisture permeability test method for moisture-proof packaging materials [cup method]. When the greaseproof paper is used after being processed into bags, the lower limit of the moisture permeability is 600 g / m2 24h is preferred, 900g / m 2 The upper limit of the moisture permeability is preferably 1500 g / m 2 24h is preferred, 1200g / m 2 By having the moisture permeability in the above range, the moisture in the packaged contents is unlikely to turn into water droplets while having good oil resistance, and since the humidity is kept at an appropriate level, the quality of the contents can be maintained at a good level.

[0035] According to the present invention, it is possible to provide greaseproof paper having excellent oil resistance and heat sealability. In addition, since the greaseproof paper has a detachable heat seal layer, it can be recycled, and since it does not use a resin film, it is possible to protect the environment.

[0036] [Manufacturing method of greaseproof paper] The method for producing the grease-resistant paper is not particularly limited, but may include, for example, a process for making a pulp slurry that is the raw material for the paper base material, a process for producing a composition for forming a heat-seal layer, and a process for applying the composition for forming a heat-seal layer to at least one surface of the paper base material.

[0037] In the papermaking process, a raw material slurry containing the above-mentioned raw material pulp, oil-proofing agent and other additives is made using a known papermaking machine.

[0038] Next, it is preferable to have a step of drying one side of the paper base material made in the papermaking step with a Yankee dryer to form a glossy surface. In this step, the surface in contact with the Yankee dryer is formed as a glossy surface. More specifically, a wet paper is pressed against the Yankee dryer with a so-called blanket, and the mirror surface of the cylinder surface of the Yankee dryer is transferred to the wet paper, thereby obtaining a glossy surface of one-sided gloss kraft paper. In the drying process with the Yankee dryer, the surface temperature of the dryer is in the range of 100°C to 150°C, and the paper is pressed against the mirror surface of the Yankee dryer. In addition, the surface not in contact with the Yankee dryer is formed as a non-glossy surface. On the non-glossy surface side, the smoothness is adjusted by adjusting the material of the blanket or the pressure of the touch roll that presses the blanket against the Yankee dryer. Among the above adjustment methods, the method of adjusting the pressure of the touch roll is preferable. As a result, it is possible to increase the difference between the front and back smoothness of the glossy surface and the non-glossy surface while maintaining the density of the paper base material. The paper base material having a glossy side and a non-glossy side can suppress blocking by laminating a heat seal layer on the non-glossy side, and the non-glossy side can exhibit excellent printability. Here, the "glossy side" refers to the side that has gloss. The "non-glossy side" refers to the side that does not have gloss.

[0039] As described above, the Beck smoothness of the surface of the paper base material onto which the heat seal layer is laminated is preferably 8 seconds or more and 30 seconds or less, and when the grease-resistant paper has a heat seal layer on one side, the Beck smoothness of the non-glossy side of the paper base material is adjusted to be within this range.

[0040] In the heat seal layer forming composition producing step, a heat seal layer forming composition containing an olefin-based resin as a main component is produced.

[0041] The composition for forming a heat seal layer can be applied by a known coating method, for example, a known coating machine such as a two-roll size press coater, a gate roll coater, a blade metering coater, a rod metering coater, a blade coater, an air knife coater, a roll coater, a brush coater, a kiss coater, a squeeze coater, a curtain coater, a die coater, a bar coater, or a gravure coater can be used.

[0042] The lower limit of the coating amount (solid content equivalent) of the composition for forming the heat seal layer on one side is 2.5 g / m 2 If the coating amount does not satisfy the lower limit, the heat seal layer may not have sufficient oil resistance and heat sealability. On the other hand, the upper limit of the coating amount is preferably 3.5 g / m. 2 If the coating amount exceeds the upper limit, blocking suppression may decrease. Also, if the coating layer becomes too thick, coating residue may be easily generated during the folding process when the coating layer is processed into a packaging bag.

[0043] For drying the applied heat seal layer-forming composition, a known drying device can be used, such as an infrared drying device, a hot air drying device, or a contact type dryer.

[0044] The greaseproof paper thus obtained can be appropriately finished using various known finishing devices such as a super calendar, a gloss calendar, a soft calendar, and a matte calendar.

[0045] <Packaging bag> A packaging bag according to another embodiment of the present invention includes the greaseproof paper. Since the packaging bag includes the greaseproof paper, the packaging bag has excellent oil resistance and heat sealability. In addition, since the packaging bag has high moisture permeability, moisture from the contents is less likely to turn into water droplets, and the humidity is kept at an appropriate level, so the quality of the contents can be well maintained.

[0046] <Other embodiments> The present invention is not limited to the above-described embodiment, and can be embodied in various other forms in addition to the above-described forms with various modifications and improvements.

[0047] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0048] [Examples 1 to 9 and Comparative Examples 1 to 2] (Paper base manufacturing) First, 100% by mass of hardwood kraft pulp [LBKP] was prepared to obtain a pulp slurry. To this pulp slurry, the oil-resistant agents (fluororesin: Daikin's "Unidyne TG8811", synthetic rubber latex: commercially available product, acrylic resin: commercially available product) were added in the amounts shown in Table 1. In addition, aluminum sulfate, retention aid, and sizing agent were added as other additives. The obtained pulp slurry was made into a paper base material using an on-top type Fourdrinier papermaking machine. The basis weight of the paper base material was 50.0 g / m 2 It was.

[0049] (Lamination of heat seal layer) Next, a heat seal layer is formed on one side of the paper base material, and the basis weight is 53.0 g / m 2 The composition for forming the heat seal layer was as shown in Table 1. The following olefin resins and coating amounts were used in the composition for forming the heat seal layer. In Table 1, "-" indicates that the corresponding component was not used.

[0050] [Comparative Example 3] A single layer of laminated paper was prepared containing a polypropylene film. The base paper is made of commercially available kraft paper (basis weight 50.0 g / m 2 ) was used. The polypropylene film was prepared by extrusion laminating a commercially available polypropylene resin using a pelleter, and laminated on only one side of the base paper to a thickness of 20 μm.

[0051] The grease-resistant paper obtained as described above was subjected to various evaluations.

[0052] (Smoothness) The Beck smoothness of the surface of the heat seal layer and the surface of the paper substrate on which this heat seal layer was laminated was measured in accordance with JIS-P8119 (1998).

[0053] (Oil resistance) The kit value of the surface and cross section of the greaseproof paper was measured according to JAPAN TAPPI No. 41 Paper and paperboard - Oil repellency test method - Kit method. A kit value of 5 or more indicates good grease resistance.

[0054] (moisture permeability) The moisture permeability of the greaseproof papers of the Examples and Comparative Examples was measured under condition B in accordance with JIS-Z0208

[1976] Moisture permeability test method for moisture-proof packaging materials [cup method].

[0055] (Heat seal strength) Using a thermal gradient tester (manufactured by Toyo Seiki Seisakusho Co., Ltd.), the samples were processed under conditions of atmospheric pressure of 2 atm, sealer pressure of 2 kg / cm, sealer time of 1 second, and seal temperature of 140°C, and then the peel strength of the heat-sealed portion was measured using a load cell type tensile tester. The evaluation criteria were as follows: ○ and △ indicate good heat-seal strength. ○: Peel strength is 3.0 N / 25 mm or more. △: The peel strength is 2.0 N / 25 mm or more and less than 3.0 N / 25 mm. ×: The peel strength is less than 2.0 N / 25 mm.

[0056] (Blocking suppression) For each of the Examples and Comparative Examples, two sheets of greaseproof paper were placed together with the heat seal layer coated surfaces, and a 1 kg pressure roller was applied to each sheet in a reciprocating motion. After storing the sheets for one day at 40°C, the sheets were peeled off with both hands, and the results were evaluated according to the following three-level scale. If the evaluation was ○ or △, the blocking inhibition was good. ○: No blocking occurs and peeling occurs smoothly. Δ: There is some blocking, but the peelability is within the range where there is no problem. ×: Blocking occurred, and peelability was poor.

[0057] The evaluation results of each of the examples and comparative examples are shown in Table 1.

[0058] [Table 1]

[0059] As shown in Table 1, Examples 1 to 9, which have a paper substrate containing an oil-proofing agent and a heat-seal layer having a surface smoothness of 9 seconds or more and 200 seconds or less, were excellent in oil resistance, heat seal strength, and blocking suppression. In particular, the paper substrate on which the heat-seal layer is laminated has a surface smoothness of 8 seconds or more and 30 seconds or less, and the coating amount of the composition for forming a heat-seal layer on one side is 2.5 g / m 2 More than 3.5g / m 2 The following Examples 1 to 3 were excellent in heat seal strength and blocking suppression properties. On the other hand, the grease-resistant papers of Comparative Examples 1 and 2, in which the surface smoothness of the heat seal layer was less than 9 seconds or more than 200 seconds, were inferior in either the heat seal strength or the blocking inhibition property. Comparative Example 3 is a polypropylene (PP) laminated paper, which is undesirable from the viewpoint of environmental pollution. In addition, since the paper has low moisture permeability, it is considered that the freshness of the contents may decrease when used as a packaging bag. As described above, the grease-resistant paper was shown to have excellent oil resistance and heat sealability. Furthermore, the greaseproof paper has a releasable heat seal layer, which makes it recyclable, and since no resin film is used, it is environmentally friendly. [Industrial Applicability]

[0060] The greaseproof paper of the present invention is environmentally friendly, has excellent oil resistance and heat sealability, and is suitable as a packaging material for food, etc.

Claims

1. A grease-resistant paper having heat sealability, A paper substrate; Heat seal layer Equipped with The paper base material has a heat seal layer laminated on one or both sides, The heat seal layer does not contain an inorganic pigment, The surface of the heat seal layer has a smoothness of 9 seconds or more and 200 seconds or less, as measured in accordance with JIS-P8119 (1998); The surface has an oil resistance of 7 or more. A greaseproof paper having a moisture permeability according to JIS-Z0208 (1976) of 600 g / m 2 ·24 h or more and 1500 g / m 2 ·24 h or less.

2. A grease-resistant paper having heat sealability, A paper substrate; Heat seal layer Equipped with The paper base material has a heat seal layer laminated on one or both sides, The heat seal layer does not contain an inorganic pigment, The surface of the heat seal layer has a smoothness of 9 seconds or more and 200 seconds or less, as measured in accordance with JIS-P8119 (1998); The surface has an oil resistance of 7 or more. The grease-resistant paper, wherein the heat seal layer has an ethylene-acrylic acid copolymer content of more than 90.0% by mass.

3. The oil-resistant paper according to claim 1 or 2, wherein the smoothness of the surface of the paper base material on which the heat seal layer is laminated, as measured in accordance with JIS-P8119 (1998), is 8 seconds or more and 30 seconds or less.

4. A packaging bag comprising the greaseproof paper according to any one of claims 1 to 3.

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