JP2012020751A - Paper food container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a paper food container excellent in heat insulation property.SOLUTION: A coating agent 3 in which thermally expandable microcapsules 4 are dispersed is applied to the surface of base paper 2, heated and dried, thereby expanding the thermally expandable microcapsules 4 and forming a heat insulation layer 5 on the base paper 2. A resin film 6 is applied to the heat insulation layer 5, thereby obtaining the paper food container 1 excellent in heat insulation property.

Description

  The present invention relates to a paper food container, and more particularly, to a paper food container excellent in heat insulation using a thermally expandable microcapsule.

  Ordinary paper food containers usually have a resin film on the inner surface (inner side) of the base paper to obtain oil resistance and water resistance. There is a hate to chip, so if you put a hot thing inside the container or heat it with a microwave oven etc., the outer surface (outside) would become hot and you could not hold the paper container.

  For this reason, as shown in Patent Document 1, a food container having a heat storage resin surface formed from a heat storage resin composition including a heat-expandable microcapsule containing a heat storage agent has been proposed. It was very doubtful whether an excellent heat insulation effect could be expected from the heat storage performance of the conductive microcapsules.

JP 2003-237848 A

  Accordingly, the inventors of the present application have repeated many trials and errors to find out the heat insulating effect of the thermally expandable microcapsules and use this to provide a paper food container having excellent heat insulating properties. Made possible.

  The present invention has been developed in view of such circumstances, and the invention according to claim 1 is characterized in that a coating agent in which thermally expandable microcapsules are dispersed on the surface of a base paper is coated and dried by heating. The heat-expandable microcapsule is expanded to form a heat insulating layer on the base paper, and a resin film is bonded onto the heat insulating layer.

  The invention described in claim 2 is based on the premise of claim 1 and is characterized in that the thermally expandable microcapsules are dispersed at a ratio of 1 to 40% by weight with respect to the coating agent.

  The invention described in claim 3 is based on the premise of claims 1 and 2, when a resin film is bonded onto the heat insulating layer, an adhesive is applied to the heat insulating layer formed on the base paper. A resin film is bonded after drying.

  According to a fourth aspect of the present invention, on the premise of the first to third aspects, when the thermally expandable microcapsule expands, the coating agent layer itself expands accordingly.

  Therefore, in the invention of claim 1, the thermally expandable microcapsules are expanded by dispersing the thermally expandable microcapsules in the coating agent, coating the surface of the base paper, and drying by heating. Since it relates to a paper food container in which a heat insulating layer is formed on a base paper and a resin film is bonded on the heat insulating layer, it goes without saying that it has oil resistance and water resistance. Even if a hot thing is put inside or heated with a microwave oven or the like, the heat insulating layer is present and the outer surface becomes hot and there is no fear that the paper food container cannot be held.

  In the invention of claim 2, since the heat-expandable microcapsules are blended at a ratio of 1 to 40% with respect to the coating agent, sufficient dispersibility is obtained at the time of blending and stirring with the coating agent. During heat drying, a uniform expansibility can be obtained.

  In the invention of claim 3, when the adhesive coated on the heat insulating layer is dried, adhesiveness as a sticky rubber is obtained, so that the bonding operation of the resin film to the heat insulating layer becomes easy, The adhesion between the two is improved.

  In the invention according to claim 4, when the thermally expandable microcapsule expands, the coating agent layer itself expands accordingly, so that a heat insulating effect can be further expected.

1 is an overall perspective view showing a paper food container according to an embodiment of the present invention. It is a principal part expanded sectional view of a base paper. It is explanatory drawing explaining the process until producing a paper food container. FIG. It is explanatory drawing of a thermally expansible microcapsule. It is an enlarged photograph which shows the state which expanded the thermally expansible microcapsule in cross section. It is an enlarged photograph which shows the state which expanded the thermally expansible microcapsule from the plane.

  The present invention applies a coating agent in which thermally expandable microcapsules are dispersed on the surface of the base paper and heat-drys to expand the thermally expandable microcapsules to form a heat insulating layer on the base paper, By pasting a resin film on the heat insulating layer, a paper food container having excellent heat insulating properties is provided.

  The paper food container 1 according to this embodiment will be described in detail below with reference to the preferred embodiment illustrated in the drawings. As shown in FIGS. The thermal expansion microcapsule 4 is expanded by applying the coating agent 3 in which the thermal expansion microcapsule 4 is dispersed and drying by heating, so that the heat insulating layer 5 is integrally formed on the base paper 2. By sticking the resin film 6 on the heat insulation layer 5, the paper food container excellent in heat insulation is obtained. In addition, although the box-shaped container was shown in FIG. 1, this invention is not limited to this, It can be set as a cylinder shape and other various shapes.

  Therefore, the process until the container 1 is manufactured will be described in detail. First, as shown in FIGS. 3 and 4, first, a sheet-like processed base paper 11 that becomes the base paper 2 of the paper food container 1 is wound on the winding roll 12. The processing base paper 11 is transferred to the “coating machine” side via a plurality of guide rolls 13. In this “coating machine”, the storage pan 14 of the coating agent 3 in which the thermally expandable microcapsules 4 are dispersed (mixed and stirred) at a certain ratio is disposed. The coating agent 3 in which the thermotension microcapsules 4 are dispersed is applied to the surface of the processing base paper 11 through the coating roll 15. In this case, if the coating amount is large, the excess amount is removed by the rod coater 16. The dispersion amount of the thermally expandable microcapsule 4 is 1 to 40%, but in consideration of the dispersion example described later, among them, the range of 10 to 20% is the most, especially in terms of weight ratio. It turned out to be preferable.

  In addition, although the brand name "Matsumoto Microsphere" manufactured and sold by Matsumoto Yushi Seiyaku Co., Ltd., whose address is 2-1-3, Shibukawa-cho, Yao-shi, Osaka, was used for the thermally expandable microcapsule 4. As shown in FIG. 5, the thermally expandable microcapsule 4 is formed by encapsulating a liquid hydrocarbon Y in a shell X made of a thermoplastic polymer such as acrylonitrile, and the microcapsule 4 is heated. As a result, first, the thermoplastic polymer constituting the shell X softens, and at the same time, the encapsulated liquid hydrocarbon Y begins to gasify and the internal pressure rises, and the microcapsules themselves expand. During expansion, the internal pressure and the tension and external pressure of the shell polymer are balanced to maintain the balloon-like expansion state. However, if heating continues, the gas diffuses and diffuses through the thinned shell X. In contrast, the tension and the external pressure of the shell X win and contract.

  Further, as the coating agent 3 in which the microcapsules 4 are dispersed, an acrylic / polyester / polyolefin resin or emulsion, PVA, EVA, or the like is used.

  Hereinafter, a dispersion example of the coating agent 3 and the heat-expandable microcapsule 4 will be shown in a weight ratio, but the present invention is not limited to this, and is adapted to the use of the product and the selected coating agent 3. The formulation can be changed.

<First dispersion example>
1. EVA 60%
2. Microcapsule 12%
3. 28% water

<Second dispersion example>
1. Aqueous acrylic emulsion 70%
2. Microcapsule 12%
3. 18% water

<Third dispersion example>
1. EVA 60%
2. Microcapsules 20%
3. 20% water

<Fourth dispersion example>
1. 90% aqueous acrylic emulsion mixture
2. Microcapsule 10%

  Of these dispersion examples, the first dispersion example was the best in exhibiting the dispersibility during blending and stirring and the expandability during heating.

  Therefore, this time, as shown in the drawing, the processed base paper 11 coated with the coating agent 3 is transferred to the “burner” side through the guide roll 13 and is heated and dried by the gas burner 17 in the process of passing through the paper. This heat drying is performed at a temperature of about 700 ° C. As a result, as shown in FIGS. 6 and 7, the heat-expandable microcapsules 4 expand about 80 times to form the heat insulating layer 5. As a result, the coating agent layer itself also expands, and a fine uneven shape appears on the surface of the heat insulating layer 5. However, it should be noted that if the amount of heating is small, the bulge of the microcapsule 4 becomes small, and if the amount of heating is large, the bulge becomes large. is there. However, when heated too much, the microcapsules 4 contract on the contrary. Moreover, even if the microcapsule 4 expands, the heat insulating layer 5 is not destroyed.

  Next, the processing base paper 11 on which the heat insulating layer 5 is formed is transferred to the “dry chemical coating machine” side through the guide roll 13. On the “dry chemical coating machine” side, a storage pan 19 for a dry adhesive 18 such as an acrylic copolymer resin is disposed. In this transfer process, the dry adhesive 18 is applied to the surface of the heat insulating layer 5. Coating is performed via the coating roll 20.

  Since the dry adhesive 18 has the property of exhibiting tackiness when water is blown off, it is transferred to the “drying dryer” side through the guide roll 13 as it is, and a gas hot air dryer (FIG. (Not shown) to obtain tackiness. In addition, the product name "Life Bond RA-1A, RA-4B" manufactured and sold by Nichiei Kako Co., Ltd., which has an address in Higashi-Osaka-shi 6-1-33 Wakae-cho, Osaka Prefecture, was used for this adhesive 18. .

  Then, the resin film 6 is transferred to the “dry laminating machine” side, and the resin film 6 is bonded to the surface of the adhesive 18 via the dielectric roll 21 by thermocompression bonding. In addition, about the resin film 6, cheap things, such as PET, PP, and PE, are used.

  Finally, the base paper 11 to which the resin film 6 is bonded is transferred to the roll cutter 23 through the pressure roll 22, cut with the roll cutter 23, punched into a predetermined shape, and then the resin film. If the six surfaces are assembled inside, a paper food container 1 as shown in FIG. 1 can be easily produced. Alternatively, even when the processed base paper 11 is wound up on a paw prill (not shown) and then cut with a roll cutter 23 and punched into a predetermined shape, the paper food container 1 is obtained in the same manner. In any case, the paper food container 1 has a heat insulating layer 5 formed between the base paper 2 and the resin film 6 and the heat insulating layer 5 is formed of the thermally expandable microcapsules 4. It is an excellent translation.

  Therefore, the produced container 1 does not cause peeling between the heat insulating layer 5 and the base paper 2 and between the heat insulating layer 5 and the resin film 6 even when hot water of about 100 ° C. is put into the container 1 and when it is cut. Since the cut powder of the heat insulating layer 5 is not generated from the cut end, the adhesiveness to the base paper 2 is good and the resin film 6 is bonded on the heat insulating layer 5. Adhesion is also good. Moreover, if necessary, it is also possible to perform offset printing on the outer surface side to which the resin film 6 is not bonded to give a desired pattern or character.

  In the above embodiment, the heat insulating layer 5 is formed on the inner side (inner surface) of the container 1, but the present invention is not limited to this, and the heat insulating layer 5 is formed on the outer side (outer surface). Alternatively, the heat insulation layer 5 can be formed on both sides.

  According to the present invention, an excellent heat insulating effect was obtained by actively utilizing the performance of the heat-expandable microcapsules. Therefore, if this is applied to various paper food containers, it will be very convenient.

DESCRIPTION OF SYMBOLS 1 Paper food container 2 Base paper 3 Coating agent 4 Thermally expansible microcapsule 5 Heat insulation layer 6 Resin film 11 Processing base paper 12 Winding roll 13 Guide roll 14 Storage pan 15 Coating roll 16 Rod coater 17 Gas burner 18 Dry adhesive 19 Housing Pan 20 Coating Roll 21 Dielectric Roll 22 Pressure Roll 23 Roll Cutter X Shell of Thermally Expandable Microcapsule Y Hydrocarbon Encapsulated in Shell

Claims (4)

  By applying a coating agent in which thermally expandable microcapsules are dispersed on the surface of the base paper and heating and drying, the thermally expandable microcapsules are expanded to form a heat insulating layer on the base paper, and on the heat insulating layer. A paper food container characterized in that a resin film is bonded to the paper.   2. The paper food container according to claim 1, wherein the thermally expandable microcapsules are dispersed at a ratio of 1 to 40% by weight with respect to the coating agent.   When bonding a resin film on a heat insulation layer, an adhesive is applied to the heat insulation layer formed on the base paper, and after drying, the resin film is bonded. The paper food container according to any one of 2 above.   4. The paper food container according to claim 1, wherein when the thermally expandable microcapsule expands, the coating agent layer itself expands accordingly.