JP2008247399A - Heat-insulating paper container - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tray-type heat-insulating paper container such as a paper cup for use in eating or drinking food after pouring hot water in it or a lunch box or the like requiring heat keeping state in a microwave oven and the like, wherein the container shows a less environmental load concerning a waste material processing and the like, has no accumulation of manufacturing energy, and shows a superior heat-insulating effect as well as a superior surface ornamental characteristic. <P>SOLUTION: This is a heat-insulative paper container 1 heated and foamed under application of a heat-insulative raw paper 2 having a foamed layer 22a at the outer surface of a paper base material 20 made of paperboard, wherein the foamed layer 22a is coated with a coating liquid having non-organic powder 23 with sodium hydrogencarbonate of 1 to 25 wt.% mixed and dispersed in a solution of water-soluble resin such as polyvinyl alcohol or the like and a foam controlling layer is applied onto the foamed layer 22a. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a heat-insulating paper container such as a paper tray for a heat-insulating paper cup or a lunch box that is heated by a microwave oven or the like for instant food or beverage that is poured by boiling water, and especially for paper. The present invention relates to a heat-insulating paper container that is molded into a container shape using foamed paper having a foamed layer on a main substrate and then heated and foamed.

  Conventionally, heat insulation cups made of foamed polystyrene for pouring hot water into the contents of instant noodles, instant miso soup, instant soup, etc. are known, but related to waste treatment with the increase in waste in recent years There are problems such as environmental hormones and the risk of elution of environmental hormones by pouring hot water, and heat-insulating paper cups that are easy to dispose of and easy to incinerate, and that do not have the risk of elution of environmental hormones, have become the mainstream. I came.

  As an example of the heat insulating paper cup, for example, as shown in the partially cutaway perspective view of FIG. 6B, the paper cup body (12) is covered with a protective cover (13) for heat insulation. There is an insulation cup (8). More specifically, as shown in FIG. 6 (b), the outer surface of the side wall (14) of the paper cup body (12), which includes the side wall (14) and the bottom wall (not shown), As shown in the sectional view of FIG. 6 (a), a fan-shaped embossed paper (16) in which one side of a liner paper (18) is embossed, and a thin paper (17) are further stuck thereon. There is a paper heat insulating cup (8) by winding and fixing a heat insulating protective cover (13) (see, for example, Patent Document 1).

  However, the above-mentioned paper heat insulating cup (8) has sufficient heat insulation by the protective cover (13), but has heat insulation wound around the outer surface of the side wall (14) of the paper cup body (12). In addition to the increase in the material of the protective cover (13) itself and its manufacturing cost, there was a problem that the manufacturing energy including its winding and the like increased.

  Further, for example, as shown in the partially cutaway front view of FIG. 7, the outer surface of the paper cup body (12) is in contact with the outer surface of the paper cup body (12), and the bottom curl is formed on the lower inner side. A paper outer sleeve (11) having (4) is covered, and the inner surface of the upper opening of the paper outer sleeve (11) is adhered so as to be in the upper curl (4) of the paper cup body (12). And a double container type heat insulating cup (7) provided with a space layer (5) between the side wall (14) of the paper cup body (12) and the paper outer sleeve (11). (For example, refer to Patent Document 2).

  However, in the double container type heat insulating cup (7), the material and the manufacturing cost of the paper outer sleeve (11) itself are increased, and the manufacturing energy for sticking it to the outer side of the paper cup body (12). In addition to the difficulty of increasing the volume, the top of the cup with hot water poured into it becomes hot, and the paper outer sleeve (13) itself collapses while being held by hand, and the paper outer sleeve (13) There was a problem that the space layer (5) between the paper cup main body (12) and the heat insulation effect was lost.

  In addition, for example, there is a heat insulating cup (not shown) in which embossed paper is wrapped and pasted on the outer surface of a paper cup body. In this heat insulating cup, since the cup outer surface has irregularities, the small size described in the recesses is small. There was a problem that characters (names of raw materials of contents, nutritional components, etc.) were difficult to read, and the appearance was not good and lacked cosmetics.

  As a solution to the above-mentioned problems, that is, problems such as increased production energy, poor heat insulation effect or lack of cosmetics, for example, as shown in the side sectional view of FIG. Insulation using post-foamed heat insulating paper (9), in which a heat-foamable microcapsule-type foaming agent (6) is contained in the intermediate layer (15) of the multilayer (three-layer) paper made with 19) There is a paper container (not shown), and this insulating paper container is heated in an oven or the like, so that the micro-layer in the intermediate layer (15) is shown in the side sectional view of FIG. There is one in which gas is generated from the capsule-type foaming agent (6) and the intermediate layer (15) swells to provide a heat insulating effect (for example, see Patent Document 3).

The above prior art documents are shown below.
JP-A-8-58762 JP 2003-191940 A JP 2002-254532 A

  However, in the heat insulating paper container using the foamed heat insulating paper (9) containing the microcapsule type foaming agent (6), most of the microcapsules themselves are mainly composed of vinylidene chloride and acrylonitrile. In addition to the problem of residual monomers, there is a risk of generation of chlorine gas, cyanide gas, dioxin, etc. at the time of disposal (incineration), and there is a problem that the burden on the environment increases.

  The present invention solves the problems of the prior art, and the object of the present invention is a lunch box that needs to be kept warm in an insulating paper container such as an instant food or instant drink that is poured by boiling water or a microwave oven. An object of the present invention is to provide a heat-insulating paper container such as a tray-like heat-insulating paper container such as a box that has a low environmental burden related to waste disposal, has a low manufacturing energy, has an excellent heat-insulating effect, and has an excellent cosmetic surface. .

  In order to achieve the above object in the present invention, first, in the invention of claim 1, a heat insulating foamed paper container using a foamed paper having a foamed layer on the outer surface of a paper substrate, The foam layer is a heat insulating paper container comprising a coating liquid in which an inorganic powder mainly composed of sodium hydrogen carbonate is mixed and dispersed in a water-soluble resin solution.

  In the invention of claim 2, the water-soluble resin in the coating solution is polyvinyl alcohol or starch, and the heat insulating paper container of claim 1 is provided.

  According to a third aspect of the present invention, the mixing ratio of the inorganic powder to the coating liquid is in the range of 1 to 25% by weight. It is.

  According to a fourth aspect of the present invention, there is provided the heat insulating paper container according to any one of the first to third aspects, wherein a foam control layer containing silicon oxide is applied to the surface of the foam layer. .

  Furthermore, in invention of Claim 5, it is set as the heat insulation paper container in any one of Claims 1 thru | or 4 by which the thermoplastic resin layer is given to the inner surface of the said paper base material. is there.

  Since this invention is the above structure, there exist the following effects.

  That is, according to the first aspect of the present invention, there is provided a heat insulating paper container formed by using a foam base paper having a foam layer applied to the outer surface of a paper base material, and then foamed by heating. Consists of a coating solution in which inorganic powders mainly composed of sodium hydrogen carbonate are mixed and dispersed in a water-soluble resin solution, so that the production energy is less than conventional double containers and the hydrogen carbonate as a blowing agent. In addition to having good foaming performance, sodium maintains good hygiene even when touched by food, etc. The gas generated during heating and foaming is mainly carbon dioxide, so there is no problem in terms of safety. It can be a heat insulating paper container.

  Further, according to the invention of claim 2, the water-soluble resin in the coating liquid is polyvinyl alcohol or starch, so that the dispersion of inorganic powder mainly composed of sodium hydrogen carbonate in the resin solution. The polyvinyl alcohol and starch are resins that are excellent in coating properties on paper and can be made into a coating solution that is more suitable for forming a foamed layer. But there is.

  In addition, according to the invention according to claim 3, by setting the mixing ratio of the inorganic powder to the coating liquid in the range of 1 to 25% by weight, a heat insulating paper container capable of obtaining a good heat insulating state, can do. If the mixing ratio of this inorganic powder is less than 1% by weight, the heat insulating property obtained by heat-treating it becomes poor, for example, inferior to polyethylene foamed paper, etc. When the mixing ratio exceeds 25% by weight, suitability for application to a paper substrate is deteriorated, and it is difficult to control foaming of the obtained foamed layer due to excessive foaming, resulting in poor surface properties. In addition to the problem, there is a problem that the material cost increases, which is not preferable.

  According to the invention of claim 4, since the foam control layer containing silicon oxide is applied to the foam layer surface, the foam control layer containing silicon oxide has gas barrier properties. Permeation of gas generated by heating is controlled (controlled), cracking of the foam layer and surface roughness due to partial overfoaming can be prevented, and excellent surface smoothness can be achieved. It can be set as the heat insulating paper container which is excellent also in the cosmetics which are not lacking in the character etc. which are printed.

  Furthermore, according to the invention according to claim 5, the thermoplastic resin layer is applied to the inner surface of the paper base material, so that a sealant layer for molding into a cup, a tray, a paper molding container or the like can be obtained. In addition, the water resistance of the paper container can be imparted.

  Therefore, the present invention has less environmental impact related to waste treatment etc. in heat insulating paper containers such as instant foods that are poured with hot water and tray-like heat insulating paper containers such as lunch boxes that need to be kept warm in a microwave oven, etc. It has excellent practical effects in applications such as a heat-insulating paper container that is not bulky in production energy, has an excellent heat insulating effect, and imparts cosmetic properties to the printed layer on the surface.

  The best mode for carrying out the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is an explanatory diagram showing an example of the heat insulating paper container of the present invention, and FIG. 2 is a schematic diagram illustrating an example of the heat insulating paper constituting the heat insulating paper container of the present invention. These are the schematic diagrams explaining an example of the foaming state of the heat insulation paper which comprises the heat insulation paper container of this invention. Moreover, FIG. 4 explains manufacture of one example of the heat insulating paper container of the present invention, and FIG. 5 is an explanatory view showing another example of the heat insulating paper container of the present invention.

  The heat insulating paper container of the present invention is made of, for example, various paperboards as shown in a cross-sectional view in which a part of FIG. 1A is a cut-out cross section and an enlarged part of the cut-out cross section in FIG. When the heat insulating paper container (1) using the heat insulating base paper (2) in which the foam layer (22a) before foaming is applied to the outer surface of the resulting paper base (20) is heated in an oven or the like, FIG. As shown in (2), it is a heat insulating paper container (1) in which the foam layer is foamed to form a foam layer (22b) having heat insulation.

  The foamed layer (22a) before foaming is coated with a coating liquid in which an inorganic powder mainly composed of sodium hydrogen carbonate is mixed in a water-soluble resin solution (heat insulating paper container ( 1), when it is heated in an oven or the like, as shown in the schematic diagram of FIG. 1 (c), the gas generated from sodium hydrogen carbonate in the inorganic powder (23) (mainly carbon dioxide) This is a post-foaming heat insulating paper container (1) in which the foam layer (22a) shown in 1 (b) is foamed to form a foam layer (22b) having heat insulation properties.

  Thus, as the foamed layer (22a) before foaming, the coating liquid in which the inorganic powder (23) mainly composed of sodium hydrogen carbonate is mixed and dispersed in the water-soluble resin solution on the outer surface of the paper substrate (20). Since the heat insulating base paper (2) is obtained by coating with, for example, to obtain the heat insulating paper container (1) that does not increase the energy cost for manufacturing compared to the conventional double container shown in FIG. Can do. Further, since the gas generated when the foamed layer (22a) before foaming containing sodium hydrogen carbonate as a foaming agent is foamed by heat treatment in an oven or the like, non-toxic carbon dioxide is the main component, so there is no safety problem. It can be set as a property paper container (1).

The paper base material (20) constituting the heat insulating base paper (2) is a paperboard of about 200 to 300 g / m ² , and especially for foods, a paper made of virgin pulp that does not contain a fluorescent dye or the like. For example, ivory, cup base paper, etc. are mentioned as suitable board paper.

  The main raw material for the water-soluble resin solution forming the foam layer (22a) is, for example, a water-soluble polymer such as starch-based resin, cellulose-based resin, protein-based resin, polyvinyl alcohol-based resin, and latex-based resin. , Polyacrylic acid salts, styrene-maleic anhydride, aqueous silicones, phosphates, ethyleneimine compounds, fatty acid esters and the like, or mixed aqueous solutions thereof.

  However, in the present invention, the water-soluble resin in the coating solution for forming the foamed layer (22a) shown in FIG. 1 (b) is taken into account in view of the applicability to the paper substrate (20) and the like. Or it is a starch.

  Thus, by using polyvinyl alcohol or starch as the water-soluble resin, the dispersion of these inorganic resin powders mainly composed of sodium hydrogen carbonate is improved in the resin solution, thereby providing a coating solution having excellent coating suitability. The polyvinyl alcohol and starch are resins excellent in the suitability for coating on paper, and are also more suitable water-soluble resins for forming the foamed layer (22a). Furthermore, these resins contain residual monomers as compared to the case of the insulated paper container using the post-foamed heat insulating paper (9) containing the conventional microcapsule type foaming agent shown in FIGS. 8 (a) and 8 (b). There is no problem or concern about generation of chlorine gas, cyanide gas, dioxin, etc. at the time of disposal (incineration), and there can be no problem that the environmental load increases.

  In addition, the inorganic powder (23) is mainly composed of sodium hydrogen carbonate, but may be a mixture of extender pigment, silica, calcium carbonate, etc. in consideration of coating suitability and whiteness. At least sodium bicarbonate is preferably 50% by weight or more from the viewpoint of foamability and heat insulation.

  In addition, an auxiliary agent such as a dispersant or an antifoaming agent can be mixed in the coating liquid in which inorganic powder mainly composed of sodium hydrogen carbonate is dispersed in the water-soluble resin solution, and this improves coating suitability. Application of the coating liquid includes a Mayer bar coater, a roll coater, a curtain coater, or a gravure coater, and may be appropriately selected depending on the state of the paper substrate (20) (winding, etc.), coating thickness, and the like. it can.

  In addition, the thickness of the foamed layer (22a) before foaming obtained by the above coating is preferably about 10 to 100 μm, which is relatively thick. If the thickness is too thick, foaming cannot be controlled, and foam film cracking occurs. If it occurs, or if it is too thin, foaming is insufficient and the heat insulation is not sufficient, which is not preferable. In addition, the foam layer (22a) before foaming preferably has a JIS-P-8119 Beck smoothness of about 10 seconds or more and less than about 1000 seconds.

  Further, for example, when the foamed layer (22a) before foaming having the above-described thickness shown in FIG. 1 (b) is heat-treated for a predetermined time in an oven or the like at a predetermined temperature, the amount of sodium bicarbonate in the foamed layer (22a) or the amount of water Although depending on the type of the functional resin, the foamed layer (22b) swelled about twice as much as the foamed layer (22a) before foaming can be obtained as shown in FIG. 1 (c).

  In the present invention, the mixing ratio of the inorganic powder mainly composed of sodium hydrogen carbonate is in the range of 1 to 25% by weight with respect to the coating solution in consideration of the heat insulating property of the foamed layer (22a), that is, the foaming property. It is what.

  Thus, it can be set as the heat insulation paper container from which a favorable heat insulation state is obtained by making the mixing ratio of the inorganic powder with respect to a coating liquid into the range of 1 to 25 weight%. If the mixing ratio of the inorganic powder is less than 1% by weight, the heat insulating property is poor. For example, it becomes inferior to polyethylene foam paper or the like. This is not preferable because there are problems such as difficulty and poor surface properties, and a problem that the cost of materials increases.

  In the present invention, for example, as shown in the side sectional view of FIG. 2A, a water-soluble resin made of polyvinyl alcohol or the like on the foamed layer (22a) surface on the outer surface of the paper substrate (20) and A heat insulating paper container using a heat insulating base paper (2) provided with a foam control layer (25) containing silicon oxide powder is provided.

  As described above, the foam control layer (25) containing silicon oxide is formed by providing the foam control layer (25) containing water-soluble resin such as polyvinyl alcohol and silicon oxide on the surface of the foam layer (22a). Since it has a gas barrier property, for example, as shown in the side sectional view of FIG. 2 (a), the foam layer (22b) foamed by the heat treatment suppresses (controls) the permeation of the gas generated by the heating of sodium bicarbonate. Further, since the crack of the foamed layer and the rough surface due to partial overfoaming and the like are prevented, the surface smoothness can be improved, and the printed layer (27 formed on the foam control layer (25)) ), In particular, a heat-insulating paper container (1) excellent in cosmetics with no missing lines such as characters.

  For example, as shown in the side sectional view of FIG. 3 (a), if this foam control layer is not present on the foam layer (22a) before foaming, the state of the coating liquid (amount of inorganic powder, dispersion state, etc.) Due to excessive heat treatment, etc., for example, as shown in the schematic diagram showing the side cross-section of FIG. 3B, the foamed layer (22b) after heating is cracked or roughened by partial overfoaming. There is a concern that the surface smoothness may be inferior, and thus the surface smoothness is inferior, leading to missing characters in the printed layer (27) thereon.

  The foam control layer (25) containing silicon oxide may be a vapor deposition film such as silica vapor deposition, in which silicon oxide powder is dispersed in an aqueous solution of a water-soluble polymer such as polyvinyl alcohol or ethylene-vinyl alcohol copolymer. It can also be.

  The content% by weight of the silicon oxide powder constituting the foam control layer (25) with respect to the water-soluble resin solution such as polyvinyl alcohol is not particularly limited, but it is 2 to 30% in consideration of coating suitability and gas barrier properties. % Is sufficient.

  The foam control layer (25) can be formed by a Mayer bar coater, a roll coater, a curtain coater, or a gravure coater. The thickness of the foam control layer (25) is not particularly limited, but may be about 3 to 10 μm. For example, foaming of the foamed layer as described above can be controlled.

  Furthermore, in the present invention, for example, as shown in FIG. 2A, a thermoplastic resin layer (26 on the inner surface of a paper substrate (20) made of paperboard or the like having a foam layer (22a) on the outer surface. ) Is used as the heat insulating base paper (2).

  Thus, by making the heat insulating base paper (2) in which the thermoplastic resin layer (26) is laminated on the inner surface of the paper base material (20), heat sealability to the paper is imparted when molding cups, trays and the like. In addition to serving as a sealant layer, water resistance can be imparted to the paper container.

  Examples of the thermoplastic resin constituting the thermoplastic resin layer (26) include olefin resins such as polyethylene resin, polypropylene resin, and polyolefin copolymer resin, nylon, polyester resin, polyvinyl alcohol, and ionomer resin. And appropriately selected according to the application.

  As a method for laminating the thermoplastic resin layer (26), there are an extrusion coating method in which a selected thermoplastic resin is melted and applied, or a method of laminating the thermoplastic resin film in a laminate.

  Further, for example, the printed layer (27) as shown in FIG. 3 (a) is not necessarily required, but the surface of the foamed layer (22a) before foaming on the paper substrate (20) or the figure. 2 (a) is applied to the surface of the foam control layer (25), and this printed layer (27) is partially printed with colored ink used for product description, etc. In some cases, the entire surface is printed with colored ink, and the printing method can be obtained by a known printing method such as an offset printing method or a gravure printing method. As described above, the surface property of the foam layer (22a) becomes important for printing.

  By using the heat insulating base paper (2) as described above, for example, a paper cup as shown in FIG. 1 (a) is prepared, and this is heated by an oven or the like at 150 ° C. for about 2 minutes. It can be set as a foam-type heat insulating paper container (1).

When producing a paper cup as an example of the heat insulating paper container (1) as shown in FIG. 1 (a), for example, a heat insulating base paper (2) as shown in FIG. 1 (b) is used. As shown in FIG. 4 (a), as shown in FIG. 4 (b), as shown in FIG. 4 (b), as shown in FIG. 4 (b), one of the left and right edges of the fan-shaped blank (40) that forms the body portion. When the body portion is formed by sealing with a general heat seal bar or the like, the portion of the laminating portion (42) is foamed, and the inner edge of the laminating portion (42) which is roughened by foaming Since there is a risk that the moisture of the contents may invade from the exposed end face (43) and the edge wick becomes worse, the heat sealing method becomes important, and in order to suppress foaming in the heat seal in this way As a sealing method, for example, a heat press method for sealing while applying pressure or an ultrasonic wave Processing by the dynamic and the like are preferably used.

  Further, as the heat insulating paper container of the present invention, for example, a heat insulating paper box (3) as shown in the perspective view of FIG. Can be used.

  The heat insulating paper box (3) is manufactured, for example, as shown in the development view of FIG. 5 (a), with a bottom plate (50), a top plate (52), and four side plates (51) connected thereto. The blanks (46) using the heat insulating base paper which has a bonding part (42) on both ends of two right and left side plates is used, and the bonding part (42) of this blanks (46) and the part of a crease are used. After heat-sealing with an ultrasonic sealer vibrator, as shown in FIG. 5 (b), an adhesive is applied to the bonding portion (42) to form a box, and this is heated in an oven at about 150 ° C. It is possible to obtain a desired heat insulating paper box (3) by heating for about minutes.

  Specific examples of the present invention will be described below.

  For foaming layer, 90 parts by weight of 10% strength polyvinyl alcohol resin (completely fighting type: manufactured by Kuraray Co., Ltd.) is mixed with 10 parts by weight of sodium hydrogen carbonate powder: Cerbon SC-K (manufactured by Eiwa Kasei) and dispersed. A coating solution was prepared.

The above coating solution was applied to the surface of 260 g / m ² ivory paper using virgin pulp as a paper substrate (20) with a Mayer bar coater to form a foam layer (22a) before foaming. The coating amount was 40 g / m ^{2 by} wet and dried to prepare a heat insulating base paper (2). This heat insulating base paper (2) was treated as a foamed paper sample in which a foamed layer (22b) was formed by treatment for 2 minutes at 150 ° C. in a ventilated oven.

  In order to compare the state of the foamed layer (22b) by replacing the water-soluble resin, the same procedure as in Example 1 was conducted except that the water-soluble resin solution was a 45% aqueous acrylic resin: Bonron (Mitsui Chemicals) aqueous solution. Thus, a sample of foamed paper was prepared.

  As a result of performing the following evaluations on the samples obtained in the above examples, the foamability of the foamed layer (22a) before foaming having a thickness of 60 μm in Example 1 in which polyvinyl alcohol was used as the water-soluble resin was the thickness. A foamed layer (22b) foamed to about 150 μm was obtained, and a uniform foamed layer (22b) could be obtained without excessive foaming. On the other hand, in Example 2 in which the water-soluble resin was replaced with the water-based acrylic resin, the dispersion state of the coating liquid was poor and the reaction occurred when partly mixed, and the foam layer (22a) before foaming having a thickness of 60 μm was thick. It remained in the foamed layer (22b) foamed to about 80 μm, and there were film cracks and the like.

  In addition, as the heat insulation property, the foamed paper sample obtained above was wound around a paper cup body, and after injecting hot water of about 95 ° C., the temperature of the surface at the time when 3 minutes passed was measured, In Example 1, it was 70 ° C, whereas in Example 2, it was 79 ° C.

  As described above, the heat-insulating paper container of the present invention is excellent in practical use in applications such as paper cups and trays for pouring hot water and food containers such as lunch boxes that need to be kept warm in a microwave oven or the like. It is effective.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates an embodiment of a heat-insulating paper container according to the present invention, in which (a) is a cross-sectional view with a part cut away, and (b) is an enlarged cross-sectional view of (a). (C) is an expanded sectional view after the heat processing of (a). The example of the heat insulating base paper which comprises the heat insulating paper container of this invention is shown, (a) is the sectional side view before the foaming, (b) is sectional drawing after heat processing. The other example of the heat insulating base paper which comprises the heat insulating paper container of this invention is shown, (a) is the sectional side view before the foaming, (b) represents the cross section after heat processing. It is a schematic diagram. It explains manufacture of an example of the heat-insulating paper container of the present invention, (a) is a plan view of blanks forming the trunk of the container, and (b) is a cylinder of the trunk. It is a fragmentary sectional view when shape | molding. The other example of the heat-insulating paper container of the present invention will be described. (A) is a plan view of the blanks, and (b) is a perspective view of a heat-insulating paper box produced using the blanks. is there. An example of a conventional paper heat insulation cup will be described. (A) is a cross-sectional view of a protective cover constituting the cup, and (b) is a cross-sectional perspective view in which a part thereof is cut away. . An example of a conventional double container type heat insulation cup will be described, and a part thereof will be a perspective view with a cutaway section. It explains one example of a heat insulating base paper constituting a conventional microcapsule type heat insulating paper container, (a) is a side sectional view before foaming, (b) is a cross section after heat treatment FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Thermal insulation paper container 2 ... Thermal insulation base paper 3 ... Thermal insulation paper box 4 ... Bottom curl 4a ... Upper curl 5 ... Spatial layer 6 ... Microcapsule type foaming agent 7 ... Thermal insulation cup 8 ... Insulating paper cup 9 ... Back foam insulation paper 11 ... Paper outer sleeve 12 ... Paper cup body 13 ... Protective cover 14 ... Side wall 15 ... Intermediate layer 16 ... Embossed paper 17 ... Thin paper 19 ... Polyethylene layer 20 ... Paper base material 22a ... Foam layer 22b before foaming ... Foam layer after heat treatment 23 ... Inorganic powder 25 ... Foam control layer 26 ... Thermoplastic resin layer 27 ... Print layer 40 ··· Fan-shaped blanks 42 ··· Laminated portion 43 ··· End faces of both ends of the laminated portion 46 ··· Blanks of paper box 50 · · · Bottom plate 51 · · · Side plate 52 · · · Top plate 53 ··· Insertion piece

Claims (5)

  A heat-insulating paper container using foamed paper with a foamed layer on the outer surface of the paper substrate, and foamed by heating. The foamed layer is a mixture of water-soluble resin solution and inorganic powder mainly composed of sodium hydrogencarbonate. A heat-insulating paper container comprising a dispersed coating liquid.   The heat-insulating paper container according to claim 1, wherein the water-soluble resin in the coating liquid is polyvinyl alcohol or starch.   The heat insulating paper container according to claim 1 or 2, wherein the mixing ratio of the inorganic powder to the coating liquid is in the range of 1 to 25% by weight.   The heat insulating paper container according to any one of claims 1 to 3, wherein a foam control layer containing silicon oxide is applied to the foam layer surface.   The heat insulating paper container according to any one of claims 1 to 4, wherein a thermoplastic resin layer is applied to an inner surface of the paper base material.

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