JPH0457768A - Food packaging bag - Google Patents

Abstract

PURPOSE:To prevent food from becoming excessively dry and vapor from condensing within a bag when the food enclosed within the bag is heated in an electronic oven by laminating the inner surface of one side of a packaging bag consisting of a gas-impermeable sheet with an aqueous sheet having a specific unit weight, gas permeability and water resistance. CONSTITUTION:A packaging bag consisting of a gas-impermeable sheet has the inner surface of at least one side thereof laminated with a hydrophobic nonwoven fabric sheet having a unit weight of at most 50g/m<2>, a gas permeability of at least 10cc/cm<2>.sec and a water resistance of at least 100mm. A series of consecutive bags having a perforation for facilitating tearing between each bag are rolled on a roller, preferably received in a case or bag-like container to permit the bag to be fed therethrough in a reoccurring sequence. The bag can be easily taken out one by one at each usage. A juicy food is first placed into a container such as dish and then enclosed within the bag or dry food is placed directly into the bag and, when such a bag is heated in an electronic oven, the water vapor being produced is prevented from condensing and, consequently, the food is prevented from becoming watery to permit the food of a fine flavor to be obtained.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a food packaging bag for preventing food from drying out when the food is cooked in a microwave oven, and further to a packaging bag that can be used to heat foods such as hamburgers and okonomiyaki in the microwave as they are packaged.

[Conventional technology]

Conventionally, when cooking food in a microwave oven at home, vinylidene chloride or polyethylene films have been used to prevent the food from overdrying. Additionally, takeout foods such as hamburgers are packaged in impermeable sheets to prevent sauce and ketchup from leaking out. These impermeable sheets include thin paper laminated with polyethylene film, thin paper laminated with aluminum foil, and further laminated with polyethylene film. Bag-shaped bags may be made of an impermeable sheet alone, or may have a part of the inside lined with a water-absorbing sheet, or a part of the bag may have a breathable waterproof film or holes to allow water vapor to pass through during heating. For light, those using processed film are used. The present applicant proposed a food container for heating in a microwave oven using a breathable waterproof sheeter in Japanese Patent Application No. 1-339578.

[Problem to be solved by the invention]

When food is wrapped in an impermeable sheet such as plastic wrap and heated in a microwave oven, there is a problem in that water vapor evaporated from the food condenses on the inner surface of the container, and the condensed water droplets adhere to the container and deteriorate the flavor. Breathable waterproof films are very expensive and are not used as wraps for heating in microwave ovens. If a breathable waterproof sheet made of microfibers or the like is used alone, it tends to overdry the food to be heated. In addition, scissors are required for cutting, making it inconvenient.Furthermore, it does not stick to bowls or plates, and does not have the retention properties of aluminum foil, so it is difficult to use it as is as a wrap. . The present inventors have conducted intensive studies to develop a packaging material for heating in a microwave oven that can be used easily like plastic wrap, does not overdry food, and does not cause condensation inside. I have completed t2.

[Means and effects for solving the problems] The present invention is a packaging bag made of an air-impermeable sheet, which has a fabric weight of 50 g/m2 or less and an air permeability of 10 cc/cm on the inside of at least one side.
A food packaging bag characterized by being laminated with hydrophobic non-woven fabric sheets having a water resistance of 100 mm or more and a water resistance of 100 mm or more, and the bag is continuous through a cutting perforation and is rolled. A food packaging bag is further characterized in that a plurality of the bags are housed in a box or bag-like container so that the bags can be taken out one by one.Outer layer The impermeable sheet used for this purpose is to prevent the moisture that evaporates from the food during heating from spreading outside more than necessary, and to prevent water and oil from seeping outside.It is made of polyvinylidene chloride, polyethylene, polypropylene, etc. Single or laminated films made of polyester, etc., thinly laminated films of polyethylene or polypropylene on paper such as thin paper, etc. are used.Polypropylene, polyester, and polyvinylidene chloride are preferable in terms of heat resistance during heating.Printing on the surface When applying this, it is preferable to use paper such as tissue paper laminated with polyethylene or polypropylene in terms of ease of printing and heat-sealing properties.Although sheets laminated with aluminum foil are impervious to electronics, Although it is not recommended because it cannot be heated in the microwave, it may be used partially in a small area due to the design.In this case, it is necessary to consider the position and size so that the food inside does not become heated. The hydrophobic nonwoven fabric sheet constituting the food packaging bag of the invention has a basis weight of 50 g/+++" or less and a water resistance that meets JIS standards.
The length is at least 100 mm, preferably 150 mm by the L-1092A method, and the air permeability is JIjL-1096.
In method A, it is 10 cc/cya"/sec or more, preferably 20 cc/am"/see or more. Since the packaging bag of the present invention is usually disposable, it is cost-effective, and
From the viewpoint of handling, it is preferable that the basis weight is small, and 50
g/m” or less.Air permeability is 1Occ/cm”/
If it is smaller than .see, the water vapor emitted by the food cannot be sufficiently diffused to the outside, and the surface of the food becomes moist. For example, the moisture permeable film (Mitsui Toatsu Espoir) has a high water pressure resistance of 2000 mm, but its breathability is approximately Qcc/c.
m”・SeC, when food is heated and cooked in a bag, condensation does not form on the top of the food, but it does form on the bottom.Also, if the water resistance is low, food may not be placed directly in the packaging bag. It is undesirable because the moisture that condenses on the inner surface of the impermeable sheet when heated returns through the hydrophobic nonwoven sheet and wets the food surface.Heat the food using a bag made of hydrophilic material, such as pulp paper with a water resistance of Qmm. When cooked, it evaporates; moisture is absorbed by the pulp paper and wets the surface of the food that comes into contact with the pulp paper, which is undesirable.The hydrophobic nonwoven fabric sheet may be made of hydrophobic material as long as it satisfies water resistance and breathability. The material may be made of a hydrophilic material such as a water-repellent material such as pulp paper, etc., but from the viewpoint of food safety and ease of processing when processing into a bag, additives and processing agents may not be added. It satisfies water resistance and air permeability without using it, and has heat-sealing and heat-cutting properties.The average fiber diameter is 10μ or less and the basis weight is 3 to 30 g/m.
Preferably, a laminated nonwoven fabric in which a reinforcing sheet is laminated on a melt-blown nonwoven fabric of polyolefin resin such as polyethylene or polypropylene having a weight of 5 to 15 g/m2 is preferably used. From the viewpoint of heat resistance during heating in a microwave oven, polypropylene having a high melting point is more preferable. If the basis weight of the melt-blown nonwoven fabric is 3 g/m'' or less, it is difficult to obtain sufficient water resistance, and if the basis weight is 30 g/m'' or more, vapor permeability decreases and the cost increases, making it uneconomical. The melt-blown nonwoven fabric is preferably laminated with another hydrophobic nonwoven fabric to form a composite sheet for reinforcement, improved water resistance, improved heat retention after cooking, and the like. Lamination of hydrophilic materials is not preferable because water resistance decreases and the food tends to absorb moisture that evaporates from the food during heating, resulting in overdrying of the food. The hydrophobic nonwoven fabric to be laminated and integrated is selected from heat bonded nonwoven fabrics, entangled nonwoven fabrics, spunpond nonwoven fabrics, etc., with a basis weight in the range of 5 to 50 g/re'', but spunpond nonwoven fabrics with high modulus and high reinforcing effect are preferred even at low basis weights. If the basis weight is greater than 50 g/m'', the laminated nonwoven fabric becomes bulky and has a hard texture, resulting in poor handling properties and high cost. As long as the lamination and integration do not impair air permeability and water resistance, flat calendering may be used to lightly adhere the entire structure, or hot embossing, ultrasonic bonding, adhesives, etc. may be used to form dots or lines. It is also possible to adhere partially or only the periphery. When partially adhering, the area of the adhesion part is generally 1 to 1 in order to balance air permeability, water resistance, strength, etc.
A range of 30% is preferable, but it varies depending on the date of each sheet and is not limited to this range. Furthermore, when flat calendering is carried out under such strong conditions that the surface becomes a melted film, dew condensation tends to form on the filmed surface, which is not preferable. The packaging bag of the present invention can achieve its purpose even if the inside of at least one side is made of the above-mentioned hydrophobic nonwoven fabric sheet, and the other side is made of an impermeable film or the like alone, but food can be directly put therein for cooking. In this case, if the lower side is made of an impermeable film alone, dew condensation tends to occur at the bottom of the food product, so it is preferable that the entire inside surface is made of the above-mentioned hydrophobic nonwoven fabric sheet. The effect of the present invention can be obtained by simply overlapping the impermeable sheet and the hydrophobic nonwoven fabric sheet, but from the viewpoint of ease of handling when packaging foods, heat embossing in the form of dots, lines, etc. It is desirable that they be integrated by bonding by a method such as , ultrasonic bonding or the like. Adhesion does not need to cover the entire surface; it is preferable that the distance between the adhesion points is, for example, 3 cm or more to ensure sufficient space between the impermeable sheet and the hydrophobic nonwoven sheet, and It is sufficient if the area around the opening is bonded to an extent that does not interfere with handling. Then, the composite sheet is folded in half in the width direction so that the hydrophobic nonwoven fabric sheet is on the inside, or the two sheets are stacked and the edges are fused and sealed. Add a fusion seal and a perforation for separation and roll it up. Alternatively, separate one sheet at a time and store multiple sheets together in a pop-up container or bag. The shape of the bag is a square or rectangle with two or three sides closed, or a triangle with two sides closed. If necessary, the bag may have a gusset to make it thicker. .

【Example】

Further, the present invention will be explained by specific examples. Example 1, Comparative Example 1 Ultrafine fiber nonwoven fabric with an average fiber diameter of 3μ and a basis weight of 5 g/lo'' obtained by melt blowing polypropylene, and a fabric with a basis weight of 13
g/m'' polypropylene spunbond nonwoven fabric was laminated and subjected to bin point embossing to make a laminated nonwoven fabric.The water resistance of this laminated nonwoven fabric was 323 mm, and the air permeability was 5.
0 cc/am''/sec. This laminated nonwoven fabric and a polyethylene film with a thickness of about 50 μm were overlapped and bonded by hot embossing in a lattice shape with intervals of about 5 cm. The weight of this laminated sheet was 20 cm, and the nonwoven fabric side was on the inside. 2
The sheets were stacked, and both ears were heat-sealed, and perforations were made across the entire width at 30cm intervals for separation, and a number of bags were made into a continuous sheet through the perforations, which was then rolled up into a roll. The resulting rolled bag could be easily separated at the perforations, and when a hamburger was placed inside and heated in a microwave, condensation formed between the laminated nonwoven fabric and the polyethylene film, but the surface of the bread remained damp. It did not have any tinge, nor did it have a dull taste, and had a good taste. On the other hand, without overlapping polyethylene film. When a hamburger was placed in a bag made only of laminated nonwoven fabric and heated in a microwave oven, the surface of the bread was a little dry. Comparative Example 2 A bag was produced in the same manner as in Example 1 by laminating a hydrophilic mixed paper with a basis weight of 15 g/m'' consisting of 70% pulp and 30% polypropylene fibers with a melt-blown nonwoven fabric instead of the polypropylene spunbond nonwoven fabric. The water resistance of the laminated non-woven fabric is 90mm, and the breathability is 15c.
When I put a hamburger in this bag and heated it in the microwave, the bottom of the bread was damp.

【Effect of the invention】

The packaging bag of the present invention can be easily taken out one by one each time it is used, and food with a lot of juice can be placed in a container such as a plate, while food with no liquid can be placed in the bag as is and placed in the microwave. It can be heated and cooked. By using the food packaging bag of the present invention, the following effects can be obtained. ■Small storage space. ■It is clean and can be easily taken out as needed for use. ■ Even when cooked in a microwave oven, the steam generated does not condense and wet the food, making it possible to obtain food with good flavor. ■Because it has a non-woven layer, it has high heat retention and can keep food warm for a long time.

Claims (3)

[Claims] (1) A packaging bag made of an impermeable sheet, with a fabric weight of 50 g/m^2 or less on the inside of at least one side, and an air permeability of 10
A food packaging bag characterized by being laminated with hydrophobic nonwoven fabric sheets having a water resistance of cc/cm^2·sec or more and a water resistance of 100 mm or more. (2) The food packaging bag according to item 1, characterized in that the bag is continuous through a cutting perforation and is rolled. (3) The food packaging bag according to item 1, characterized in that the plurality of bags are stored in a box or bag-like container so that the bags can be taken out one by one.