JPH0582203B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD OF THE INVENTION The present invention relates to disposable food packaging. In particular, it relates to materials for browning foods when cooking them using microwaves to obtain a flavor similar to that of conventional cooking methods, and for accelerating the heating of liquid foods such as soups. BACKGROUND TECHNOLOGY Conventionally, microwave cooking has not been able to brown foods like normal cooking, and the flavor has not been as good as that of normal cooking methods. For this reason, conventional methods have been used to brown foods by incorporating into food containers a film or layer that is particularly heated by microwaves. For example, a thin layer of a semiconductor such as tin oxide is applied to a ceramic container (JP-A-50-9132, JP-A-50-9133).
(Japanese Unexamined Patent Publication No. 1984-84391), an example of applying aluminum foil to the food itself in the same way as disaccharides (Japanese Patent Application Laid-Open No. 1984-84391), and an example of coating the food itself with an edible material that easily browns, such as a disaccharide (Japanese Unexamined Patent Publication No. 1984-84391). Publication No. 95144, JP-A-51-95145
Examples of vapor-depositing an aluminum film on a base sheet (Japanese Patent Laid-Open No. 53-99280), Examples of using a carbon material to be heated (Japanese Patent Laid-Open Nos. 56-42022, 44534-1983) Furthermore, an example using a very thin conductive film (Japanese Patent Publication No. 15548/1983)
and so on. However, these methods have problems in that they do not provide sufficient heating effects or browning, and that they themselves burn due to heating, and are also expensive. Problems to be Solved by the Invention In view of the current situation, the inventors of the present invention have conducted extensive research and have found that when a heat-resistant insulating protective layer is provided on a conductive sheet made of a conductive substance, a heat-resistant pigment, and fibers, good heat generation properties can be achieved. They discovered that food can be browned without burning the heat-generating sheet itself, leading to the completion of the present invention. An object of the present invention is to provide a disposable, inexpensive paper food container material. Another object of the present invention is to provide a heating sheet with improved heat resistance that browns food, accelerates heating of food, and prevents the heating sheet itself from burning in microwave cooking. Means for Solving the Problems The present invention provides a heating accelerator for microwave cooking, characterized in that a heat-resistant insulating protective layer is provided on at least one side of a conductive sheet containing a conductive substance, a heat-resistant pigment, and fibers. It is. The heating accelerator of the present invention is used as a container for cooking food in a microwave oven such as a microwave oven. For example, it can be used as a food container itself, such as as a saucer for beautifully browning foods such as pies, and for other paper applications, a container containing food can be placed on the heating accelerator of the present invention and heated. You can also do that. Furthermore, when cooking liquid foods such as soup in a microwave, the foods usually do not undergo convection. As a result, for example, noodles were not mixed sufficiently and were sloppy. However, when the sheet obtained according to the present invention is used at the bottom of a food container, the food is heated from below, making it possible to generate convection currents. Although the conductive sheet may be formed by any method, for example, a dry or wet paper-making method that is normally used for manufacturing nonwoven fabrics, paper, etc. can be suitably used. The ratio of the fibers and heat-resistant pigments in the conductive sheet to the conductive substance that generates heat is 0.5 parts by weight of the conductive substance per 100 parts by weight of the fibers and heat-resistant pigments.
The range is from 2000 parts by weight. This is because the degree of heat generation differs depending on the conductive material used, so the amount to be blended also differs depending on the material. For example, in the case of a conductive substance with high conductivity and a high aspect ratio, such as metal fiber, the blending amount is sufficient in the range of about 0.5 to 10 parts by weight, and in the case of a powdered conductive substance, it is sufficient to mix 1000 to 2000 parts by weight. It is necessary to mix approximately parts by weight. The relationship between conductivity and calorific value is currently not well understood. It is generally believed that eddy currents are generated in conductive materials by microwaves, and that heat is generated when the currents flow through the antibodies. The materials used in the present invention are as follows. The fibers serve as a binder for forming a sheet of conductive material. Considering the case of wet paper making, cellulose fibers are effective, but when the heating accelerator exhibits higher heat generation properties, inorganic fibers with high heat resistance are preferable. Examples of materials that can be used are listed below. Examples of cellulose fibers include wood pulp and linter pulp for paper making, and these fibers may be used alone or in combination. Furthermore, in addition to cellulose pulp, there are natural fibers such as cotton, chemical fibers such as rayon, polyvinyl alcohol fibers, polyester and polyacrylonitrile, synthetic pulps such as polyethylene and polypropylene, and inorganic fibers such as rock wool and glass fibers. It may be a pulp slurry containing. The conductive substance is a substance that causes the heating accelerator for microwave ovens to generate heat. Highly conductive and high aspect ratio metal fibers are preferred, but other materials can also be used. Examples of substances used are shown below. Fibers, granules or whiskers of metals such as steel, stainless steel, copper, aluminum, nickel and nickel chrome, metal oxides such as tin oxide and antimony oxide, fibers and powder coated with these metals and metal oxides. There are grains or whiskers, fibers, whiskers, and granules of carbon and inorganic and organic substances that are fired in carbon and reducing atmosphere to give conductivity, and these can be used alone or Mix and use. The conductive sheet of the present invention contains a filler in order to improve the whiteness of the base paper, improve suitability for printing, and impart nonflammability. In that case, the filler is not particularly limited as long as it has heat resistance, and any filler commonly used in paper making can be used. Preferred fillers include aluminum hydroxide, dawsonite, calcium hydroxide, magnesium hydroxide, calcium carbonate, gypsum, calcium aluminate, zinc borate, barium borate, borax, kaolin clay, alumite, and basic magnesium carbonate. Possible powders include inorganic hydrous compounds, perlite, antimony oxide, red phosphorus, and molybdenum-containing compounds. In the wet papermaking method, other paper-making aids such as a paper strength enhancer, a sticky agent, a sizing agent, etc., which are commonly used, may be used as necessary. The heat-resistant insulating protective layer serves as a protective layer for contact between the food and the conductive sheet, and also provides wettability and blocks air to prevent the conductive sheet from catching fire. It is necessary to provide it on at least one side of the conductive sheet. Examples of the material for the heat-resistant insulating protective layer include a resin film layer made of polyester such as polyethylene terephthalate, polysulfone, polymethylpentene, or methylpentene copolymer. The insulating protective layer may be provided by any method such as dry lamination or extrusion lamination. Furthermore, in order to improve adhesion at that time, the conductive sheet may be coated with an anchoring agent or subjected to activation treatment such as corona treatment. EXAMPLES Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples. The following weight ratios are expressed based on insulation dry weight. Example 1 400ml of freeness in a large amount of water being stirred
CSF softwood bleached kraft pulp 47.5 parts by weight and 47.5 parts by weight
Part by weight of aluminum hydroxide (manufactured by Showa Denko K.K., H
-42), 5 parts by weight (pulp and aluminum hydroxide)
5.26 parts by weight per 100 parts by weight of acrylic fiber whose surface is coated with nickel metal and 1 part by weight of cationic polyacrylamide (hereinafter referred to as PAM) (manufactured by Hakuto Kagaku Co., Ltd., R-605). , mix for a few minutes. Then, 0.1 part by weight of anionic
After adding PAM and stirring for several minutes, paper was made according to a conventional wet paper making method. At that time, the dispersion concentration was approximately 0.2%. A 25 μm thick PET film was laminated on both sides of this sheet to obtain a heating accelerator for microwave ovens. Example 2 In a large volume of water with stirring, 30 parts by weight of pulp, 68 parts by weight of aluminum hydroxide, 2 parts by weight (2.04 parts by weight per 100 parts by weight of pulp and aluminum hydroxide)
weight part) stainless steel fiber (8 μm diameter and 3 mm length)
SUS304 stainless steel fiber (manufactured by Nippon Seisen Co., Ltd.) and 1 part by weight of cationic PAM were added and mixed for several minutes. Subsequently, 0.1 parts by weight of anionic PAM was added and stirred for several minutes, and then paper was made according to a normal wet paper making method. Next, a PET film was laminated in the same manner as in Example 1 to obtain a heating accelerator for microwave ovens. Table 1 shows the effects of heating in a microwave oven using the heating accelerator of the present invention. Pour 50c.c. of 20℃ tap water into a Pyrex beaker.
The heating accelerator obtained according to the present invention was cut into 2.5 cm square pieces and pasted on the outside bottom of the beaker, and microwave cooking was performed for 30 seconds in a regular microwave oven. We investigated the rise in temperature of the water during this time. As a result, when nothing is pasted (Comparative Example 1)
It was shown that the temperature of the heating accelerator of the present invention increases compared to that of the present invention.

【table】

[Table] Effects of the Invention As explained above, the heating accelerator of the present invention is produced by mixing a conductive substance with fibers and a heat-resistant pigment to make paper when manufacturing a conductive sheet, and adding heat-resistant insulation to at least one side of the sheet. By providing a protective layer, it is possible to brown foods in microwave cooking, and the heating accelerator itself does not burn, resulting in improved heat resistance at low cost and continuously. This has the effect of providing a heat generating sheet.

Claims (1)

[Scope of Claims] 1. A heating accelerator for microwave cooking, characterized in that a heat-resistant insulating protective layer is provided on at least one side of a conductive sheet containing a conductive substance, a heat-resistant pigment, and fibers. 2. The conductive sheet may be made of metals such as steel, stainless steel, nickel chrome, copper, or aluminum, or metal oxides such as zinc oxide, tin oxide, or antimony oxide, or fibers, whiskers, or powder coated with these materials. A sheet in which a conductive material selected from granules, fibers, powders, or flakes made of carbon or organic or inorganic substances imparted with conductivity through reduction is dispersed. The heating accelerator for microwave cooking according to claim 1, characterized in that: 3. Claims 1 or 2, characterized in that the heat-resistant insulating protective layer is made of a synthetic resin selected from the group consisting of polyester, polysulfone, polymethylpentene, methylpentene copolymer, etc. The heating accelerator for microwave cooking described above. 4 Heat-resistant pigments include aluminum hydroxide, dawsonite, calcium hydroxide, magnesium hydroxide, calcium carbonate, gypsum, calcium aluminate, zinc borate, barium borate, borax, kaolin clay, alumite, basic magnesium carbonate, etc. inorganic-containing compounds, or perlite,
The heating accelerator for microwave cooking according to claim 1, 2 or 3, which is selected from powders such as antimony oxide, red phosphorus, and molybdenum-containing compounds. 5 The fibers are wood pulp, cellulose pulp such as linter pulp, natural fibers such as cotton, rayon, polyvinyl alcohol fibers, polyester, polyacrylonitrile, phenolic fibers, fluororesin fibers, meta- or para-aramid fibers. , organic fibers such as polyamide-imide fibers, synthetic pulps made of polyethylene, polypropylene, etc., inorganic fibers such as alumina fibers, rock wool, and glass fibers. Promotion material.