JP2019108172A - Method of manufacturing container for heated food using microwave oven - Google Patents

Abstract

To provide a method of manufacturing a container for a heated food using a microwave oven which is configured to: propose a new exhaust structure that replaces exhaust of steam using a tongue-shaped opening by a conventional U-shaped or V-shaped slit and enables good steam exhaust, at the same time; realize improvement of sealing performance and suppression of foreign material contamination; and include a lid part in which an exhaust part is formed by which perforation work time can be reduced, work efficiency is improved, and is composed of exhaust elongated holes.SOLUTION: In a lid fitting container 1 which comprises a container body part 100 and a lid body part 10 made of a synthetic resin sheet, in obtaining the lid body part by forming an exhaust part for exhausting to the outside steam generated from a food product stored in the container body part, a plurality of exhaust elongated holes 21 having width of 0.15 to 1.0 mm are drilled to form a group of exhaust elongated holes 20 by turning on irradiation of a laser beam on the lid body part to form a through hole by the lapse of preparation time (t), thereafter by turning off the irradiation of the laser beam after expanding the through hole to a predetermined long hole shape by the lapse of operation time (t).SELECTED DRAWING: Figure 1

Description

  The present invention relates to a microwave oven-heated food container, and more particularly to a method of manufacturing a container capable of efficiently discharging water vapor from a lid.

  When cooking cooked food at a retail store such as a convenience store or the like after cooking or bringing it home after cooking, the container for packaging these foods has a container body portion and a lid portion fitted with the opening thereof. It consists of a combination. In particular, since it is a single-use container used for one-time use such as storage, display, and sale of food, the lid fitting structure is simplified as much as possible. Therefore, currently, molded articles of synthetic resin sheets are the mainstream of containers.

  A microwave oven (microwave irradiation) is usually used for cooking and reheating food. Therefore, the food container is provided after being put in a microwave and heated as it is. Focusing on foods actually sold, there are foods with a large amount of water such as soups, and foods with a small amount of water per weight such as stir-fry, etc. The types of foods are quite versatile. The problem here is that water vapor is generated from the food in the container when the food is cooked by the microwave oven.

  In the lid fitting container, if the fitting between the container body and the lid is loosened, exhaust of the internally generated water vapor is easy. However, when the fitting on the lid side is loose, there is a concern that foreign matter may be mixed due to problems such as the lid being easily detached at an intermediate stage of manufacturing, shipping and display. For this reason, the reputation from the food purchaser is not desirable. Then, the cover which formed the hole part for exhausting the water vapor | steam generated internally to the container exterior is proposed (refer patent document 1, 2 grade | etc.,). According to the lid of the container represented by patent documents 1 and 2, the tongue-like opening by U-shaped or V-shaped cut is formed in the lid. Water vapor is released to the outside of the container through this tongue-shaped opening.

  The exhaust efficiency of the tongue-shaped opening with a U-shaped or V-shaped cut is good. However, the fact that the exhaust of water vapor is good also increases the risk of foreign matter intrusion from the tongue-like opening. Therefore, in this case, a sealing tape for closing the tongue-like opening may be attached. Furthermore, a film member for covering the tongue-like opening may be separately covered if necessary. For example, when a film member is placed, a wall surrounding the tongue-shaped opening is provided on the lid side, and a gap is formed around the tongue-shaped opening. And a passage of water vapor is formed also in this wall part, and the structure was complicated. Moreover, when the tongue piece by a cut is broken and it falls in the inside of a container, the problem in which the foreign material itself is mixed is also included.

  As described above, containers using an existing structure for exhausting water vapor require materials other than those necessary only for food packaging, which inevitably raises costs. In addition, the shape of the tongue-shaped opening by cutting is uniform, and there are many restrictions on the peripheral structure.

JP, 2012-50672, A Utility model registration No. 3056026

From a series of circumstances, the inventor has been searching for a new exhaust structure to replace water vapor exhaust using a tongue-shaped opening with a U-shaped or V-shaped incision. Among them, it was found that a structure in which a fine long hole exhaust part was provided in the lid of the container was effective. And since it was a fine long hole, it turned out that the tolerance to breakage or foreign material mixing is also good.

The present invention has been made in view of the above-mentioned point, and proposed a new exhaust structure replacing the water vapor exhaust using a tongue-shaped opening with a conventional U-shaped or V-shaped incision, It is possible to achieve efficient steam exhaust, at the same time to improve the sealing performance and to suppress the contamination, and at the same time, it is also advantageous in reducing the material cost, with less restrictions on the shape of the lid, compared to the circular hole shape. Disclosed is a method of manufacturing a container for a microwave oven heated food having a lid portion having an exhaust portion formed of a long exhaust hole , which can shorten a drilling operation time and improve the operation efficiency.

That is, according to the first aspect of the present invention, there is provided a lid fitting comprising a container main body for containing food for microwave oven heating, and a lid made of a synthetic resin sheet to be fitted with the opening of the container main body. a container, wherein obtain a lid portion forming the exhaust part for exhausting water vapor generated from the food contained in the container main body to the outside Runisaishite, said lid face turned to preparation time application of the laser beam to (t ₃ After forming a through hole by the passage of) and expanding to a predetermined long hole shape by the passage of the working time (t ₄ ) after that, the emission length of width 0.15 to 1.0 mm by turning off the irradiation of the laser beam The present invention relates to a method of manufacturing a container for microwave oven heating food characterized in that a plurality of holes are formed to form an elongated exhaust hole group.

According to the manufacturing method of the container for microwave oven heating according to the invention of claim 1, a lid made of a container main body for containing food for microwave heating, and a synthetic resin sheet fitted with the opening of the container main body the closure fitting vessel equipped with a body portion, Runisaishite obtain the lid portion forming the exhaust part for exhausting water vapor generated from the food contained in the container main body portion to the outside, the irradiation of laser beam to the lid surface width by turning off the irradiation of the laser beam after expansion to a predetermined long hole shape with the lapse of turning on, preparation time (t ₃₎ has elapsed by the through-hole formation and subsequent work time (t ₄₎ 0 . For exhausting water vapor using a tongue-shaped opening with a conventional U-shaped or V-shaped cut in order to form a plurality of elongated exhaust holes by forming a plurality of elongated exhaust holes of 15 to 1.0 mm Instead, good water vapor emissions And sealing performance improvements, achieves contamination suppression, more efficiently can be exhausted steam, together less restriction on the shape of the lid portion, it is possible reduce material costs. In addition, since the exhaust long hole can be easily and quickly formed in the lid surface, the drilling operation time can be shortened as compared with the circular hole shape, the operation efficiency is improved, the production amount is increased, and the mass productivity is particularly excellent. In particular, in the case of conventional physical processing methods such as needle stick and drill, it takes a long time and, in addition, there is a point that sufficient processing accuracy can not be obtained. Although it can not be wiped out and it takes time and effort for subsequent cleaning, such problems can be solved at once with laser beam irradiation.

It is a whole perspective view of the isolation | separation state of the container for microwave oven heating which concerns on one Embodiment of this invention. It is a 1st fragmentary sectional view of the container for microwave oven heating. It is a 2nd fragmentary sectional view of the container for microwave oven heating. It is a time chart which shows the relation between laser beam irradiation and penetration. It is a perspective view of the exhaust long hole group vicinity of other embodiment. It is a top view of the top view figure of the exhaust long hole group. It is the enlarged photograph which image | photographed the exhaust long hole group of the cover part. It is an enlarged photograph of the exhaust long hole group. It is a photograph of the lid part after microwave oven heating.

  The food container 1 according to one embodiment of the present invention is a combination of the container body 100 and the lid 10 fitted with the opening 101 of the container body 100, as shown in the overall perspective view in the separated state of FIG. It consists of In particular, the food is contained in the container interior 103 of the container body 100, and is heated or heated by microwave irradiation of the microwave (heat cooking) while the lid 10 is covered. Therefore, the food container 1 is a "microwave heated food container".

An exhaust long hole 21 is formed in the lid surface portion 11 of the lid portion 10. As illustrated, a plurality of the elongated exhaust holes 21 are provided, and a plurality of the elongated exhaust holes 21 are gathered to form an exhaust portion including the elongated exhaust hole group 20. During heating or heating by the microwave, the water vapor generated from the food C (see FIG. 3) contained in the container body 100 is exhausted to the outside of the food container 1 through the long exhaust holes 21. Since a plurality of elongated exhaust holes 21 are formed to form the elongated exhaust hole group 20, water vapor can be exhausted more efficiently. In the lid portion 10 of the present embodiment, a concave portion 30 appropriately dug down from the lid surface portion 11 is formed on the whole or a part of the lid surface portion 11. An elongated exhaust hole group 20 is formed in the concave portion 30. Further, in the drawing, the lid surface upper peripheral wall portion 35 is formed so as to surround the concave portion 30.

  By provision of the concave portion 30, when the water vapor jetted from the long exhaust hole 21 is liquefied and becomes water droplets, the water droplets are accumulated in the concave portion 30 and do not spread in the lid surface portion 11. As a result, the wet portion of the lid surface portion 11 can be reduced. The lid surface upper peripheral wall portion 35 is an enclosure and is provided for the purpose of preventing the leakage of water droplets.

  The fitting of the illustrated container body 100 and the lid 10 is referred to as an inner fitting, in which the periphery of the lid 10 is fitted into the opening 101 of the container body 100. Around the lid portion 10, a peripheral wall portion 15 having a U-shaped cross section that fits inside the opening portion 101 of the container main body portion 100 is provided. In the form of the inner fitting, the close contact between the container body 100 and the lid 10 is strong. Therefore, it becomes difficult to detach lid part 10 easily.

  In the container body portion 100, the opening step portion 107 is provided in the opening portion 101, and the peripheral wall portion 15 of the lid portion 10 can be received and fitted inside. The container body 100 is formed of an opening 101, a body 104, and a bottom 105 from the upper side, and becomes a pot-shaped or bowl-shaped container having an inner volume sufficiently corresponding to the amount of food. The cross-sectional shapes of the container body 100 and the lid 10 are appropriate and are circular in the drawing. It is also possible to have a cross-sectional shape such as a polygon or an oval.

  Food containers 1 (combination of container body 100 and lid 10) are mainly sold at convenience stores, supermarkets, department stores, restaurants, delicatessen specialty stores (delicatessen), coffee shops, shops such as service areas, etc. Containers used for packaging food including various dishes such as lunch, sugar beet, noodle dishes, soup dishes, and also various beverages such as coffee, cocoa, black tea, green tea and herbal tea. The mainly envisaged application is a single-use container (disposable container) used for one-time use called one-way or disposable. By using a single-use container, it is convenient for food hygiene management.

  The use of the food container 1 is mainly for use as a single-use container. Therefore, the lid portion 10 is formed of a synthetic resin sheet (plastic resin sheet) which can be mass-produced inexpensively and simply. Specifically, the lid 10 is a sheet (synthetic resin sheet) of a thermoplastic resin such as polyethylene, polypropylene, polystyrene, polyethylene terephthalate (PET resin) or the like, and further, a biodegradable thermoplastic resin such as polylactic acid. It is a sheet. Although the thickness of the synthetic resin sheet is appropriate, it is about 1 mm or less in thickness, and usually 200 to 700 μm in thickness. Then, the synthetic resin sheet is molded by vacuum molding. When a synthetic resin sheet is used as a raw material, vacuum forming is simple and optimum in consideration of mass productivity at the time of molding, processing accuracy and the like. In addition, as described later, this is because processing by laser beam irradiation is also considered.

  In the combination of the container body portion 100 and the lid portion 10, the raw material resin of the synthetic resin sheet may be the same type or a different type. In particular, since the food container 1 copes with heating by a microwave oven, the container main body side may be made of expanded polystyrene or paper in consideration of heat conduction. The kind of resin to be used is suitably selected by the use, the contents, and the package object. In the embodiment disclosed in FIG. 2 etc., the lid 10 is made of polystyrene, and the container body 100 is made of expanded polystyrene.

  The fitting portion of the container body 100 and the lid 10 in the illustrated embodiment and the long exhaust hole group 20 (long exhaust hole 21) in the illustrated embodiment will be described using the partial cross-sectional views of FIGS. 2 and 3. FIG. 2 shows the lid in the separated state, and FIG. 3 shows the lid in the fitted state (fitting or joining). The peripheral wall 15 of the lid 10 with a U-shaped cross-sectional view is formed of the lid contact wall 16, the circumferential groove bottom 17, and the inner side wall 18. A flange portion 19 is provided on the outer edge of the lid close contact wall portion 16. In the opening 101 of the container body 100 corresponding to this, the outer flange portion 109, the opening peripheral wall portion 106, and the opening step portion 107 are formed at the lower end thereof.

  Furthermore, as understood from the state of FIG. 3, when the peripheral wall 15 of the lid 10 is fitted into the opening 101 of the container body 100, the lid adhesion wall 16 is in close contact with the opening peripheral wall 106 ( Wear it. Thus, the airtightness of the inside of the food container 1 is enhanced. However, the escape route of the water vapor generated from the food C accommodated in the inside of the container 1 for food by that amount is lost. Therefore, the internally generated water vapor Vp is released to the outside of the food container 1 through the long exhaust holes 21 formed in the lid surface portion 11 of the lid portion 10. In this manner, the food container 1 is abnormally expanded, and the problem of deformation or unnatural opening of the lid is avoided.

  A laser beam is irradiated to the lid surface 11 to form the long exhaust holes 21 in the lid surface portion 11 of the lid surface portion 11 of the lid body 10. In the case of physical processing methods such as needle piercing and drilling, for example, when forming the elongated exhaust holes 21, in addition to requiring much time, there is a point that sufficient processing accuracy can not be obtained. In addition, in the case of hole formation, the problem of the generation of fine powder can not be removed, and it takes time and effort for subsequent cleaning. Therefore, irradiation of a laser beam is used because it is possible to easily and quickly form an elongated exhaust hole in the lid surface.

  The laser beam is not particularly limited as long as it can obtain processing output, processing accuracy and the like, and various lasers such as a carbon dioxide gas laser, a YAG laser, a semiconductor laser, and an argon laser and their irradiation devices are used. As described above, when the material of the lid portion is formed of a sheet of synthetic resin, the elongated exhaust holes are drilled easily and in a short time by laser beam irradiation. Especially excellent in mass productivity.

  The shape of each exhaust elongated hole 21 is exactly a rectangular shape having semicircular end portions (see FIG. 8). However, the shapes of both end portions are ignored as an error range, and the aperture area is calculated simply as a rectangle. Also in the following, the exhaust long hole will be described as a rectangle. Here, the exhaust long holes 21 constituting the long exhaust hole group 20 will be described in more detail. First, the width (short side of the rectangle) of each of the elongated exhaust holes 21 is, for example, 0.15 to 1.0 mm. More preferably, the width of the elongated exhaust hole 21 is 0.3 to 0.5 mm.

  The lower limit of the width of the elongated exhaust hole 21 is to obtain an opening amount sufficient for exhausting water vapor generated at the time of microwave oven heating. The lower limit of 0.15 mm of the width is a value roughly considering the current processing technology. If the width of the elongated exhaust hole 21 is less than 0.15 mm, it is considered that the elongated exhaust hole becomes too narrow, and the exhaust efficiency of water vapor from the elongated exhaust hole 21 decreases. As a result, the lid 10 fitted to the container body 100 is easily detached by the internal pressure. It is also considered as the lower limit on the accuracy of the laser beam irradiation apparatus.

  In addition, when the lid 10 formed of a synthetic resin sheet is irradiated with a laser beam, the resin sheet is dissolved at the irradiation site to open a hole. However, if the width of the setting is too narrow, there is a possibility that the melted resin may be bonded to each other when it is cooled and solidified due to the heat of laser beam irradiation. As a result, a desired appropriate elongated exhaust hole is not formed at the irradiation site, and sufficient steam exhaust is lost. Therefore, the lower limit of the width is 0.15 mm, preferably 0.3 mm, for the purpose of making it difficult to cause inadvertent rejoining.

  The upper limit of the width of the elongated exhaust hole 21 is to have a size for effectively suppressing the entry of foreign matter into the inside of the food container 1. For example, in the case of a minute insect or the like generally recognized as a foreign matter, when the width is smaller than 1.0 mm, the penetration into the container is substantially prevented. Therefore, the upper limit of the width is 1.0 mm, more preferably 0.5 mm.

  Next, the length of the elongated exhaust hole 21 is, for example, in the range of 1 to 12 mm, preferably in the range of 4 to 7 mm. The width of the elongated exhaust hole 21 is fine as described above. Therefore, an appropriate length is required because it is effective for exhausting internally generated water vapor. The lower limit of the length can be approximately realized as a long hole and is an amount considering the exhaust of water vapor. The upper limit of the length is due to the need to maintain the strength of the lid 10 itself. In the case where the lid portion 10 is formed of a synthetic resin sheet, as the length of the elongated exhaust hole 21 becomes longer, bending deformation or the like tends to occur near the elongated exhaust hole. Then, although the width of the long exhaust hole 21 is narrowed as described above, the long exhaust hole 21 is easily opened in a spindle shape. Then, in order to suppress the opening accompanying such a careless deformation of the elongated exhaust hole, the upper limit of the length of the elongated exhaust hole is 12 mm, for example, and preferably 7 mm.

In addition, the sum of the open areas of the exhaust long hole group 20 (exhaust portion) formed by collecting a plurality of long exhaust holes 21, that is, the open areas of all the long exhaust holes 21 on the lid surface 11 (ie, The sum of the width and length of the elongated exhaust hole is exemplified in the range of 0.3 to 100 mm ² . The minimum amount of the total open area corresponds to the area when two minimum elongated exhaust holes (width: 0.15 mm, length: 1 mm) are formed. Of course, the area amount is a value for food with a very small amount of water vapor generation. Therefore, in consideration of the types of food that can be handled, the lower limit of the total of the practical open area is considered to be 0.5 mm ² , and further 1 mm ² .

For example, in the case of noodle cooking, the volume of the container for food also increases because the amount of soup in addition to the noodles is large. Then, the heating time by the microwave oven becomes long, and the amount of water vapor generated in the entire container relatively increases. In this case, in order to promote the good exhaust of water vapor from the long exhaust holes, it is necessary to increase the total opening area. However, even if the elongated exhaust holes are increased beyond the necessary capacity, there is a concern that the labor for drilling may increase and the strength of the lid may decrease. Therefore, 100 mm ² as the upper limit of the total open area, 80 mm ² are derived as a more preferable upper limit. Since the total open area of the elongated exhaust hole group is in the above-mentioned range, the microwave oven heated food container (lid part) can cope with many foods distributed in the market.

  The great advantage of adopting the shape of the long exhaust hole 21 described above is that the working time is shortened. This is particularly effective in forming the elongated exhaust hole group 20 constituted of the plurality of elongated exhaust holes 21. In the embodiment, a laser beam such as a carbon dioxide gas laser is irradiated to the lid surface portion 11 of the lid portion 10, and the long exhaust hole 21 is formed. About this situation, the work time chart (schematic diagram) of FIG. 4 is assumed. The horizontal axis in the figure is time (t).

The upper part of FIG. 4 corresponds to, for example, the case where a circular hole-shaped exhaust hole is formed. In the figure, the repetition on the unevenness of “_Π” indicates the irradiation (ON: upper side) of the laser beam and its stop (OFF: lower side). A figure consisting of a combination of S-shaped and straight lines directly below it is the appearance of a hole formed in the lid portion upon irradiation. In particular, it may be read as the amount of penetration (depth). The stretched S-shaped portion is in a state in which the resin sheet of the lid portion is melted by the laser beam irradiation. It is a preparation state which has not yet reached penetration immediately after so-called irradiation, and the time in between is represented as "t ₁ ". The flat portion is a state in which a hole is developed to a predetermined size through it. It is a so-called actual working state, and the time in between is represented as "t ₂ ". Then, the time is not either, for example, expressed as the waiting time, such as moving to another bore (t _i).

As can be seen from the ON-OFF state of the laser beam irradiation and the graph of the amount of drilling, not all of the laser beam irradiation time is actually the time for actually expanding the hole, but the preparation time for digging the hole (t ₁ ) Also occur. In the case of the circular hole-shaped exhaust hole, the preparation time (t ₁ ) and the operation time (t ₂ ) are frequently repeated in order to form a plurality of fine holes. Therefore, the preparation time (t ₁ ) is inevitably accumulated. Furthermore, the irradiation position is changed to another place one after another in order to form a plurality of fine holes. Then, position adjustment and the like during that time becomes the waiting time (t _i ), and the time is also accumulated without fail.

On the other hand, the lower part of FIG. 4 corresponds to the case where the elongated exhaust hole disclosed in the present invention is formed. In the figure, the repetition on the unevenness of “_Π” indicates the irradiation (ON: upper side) of the laser beam and its stop (OFF: lower side). However, since the long exhaust hole is long, the irradiation time is set to be long. A figure consisting of a combination of S-shaped and straight lines directly below it is the appearance of a hole that is formed in the lid by irradiation and can be read as the amount of penetration (depth). As in the upper stage, the stretched S-shaped portion is in a preparation state in which the resin sheet of the lid portion is dissolved by the irradiation of the laser beam, and the time between them is represented as “t ₃ ”. A flat part is an actual working condition in which a hole is developed to a predetermined size (length) through, and the time is represented as "t ₄ ". Also in this example, a waiting time (t _j ) such as position adjustment for changing the irradiation position occurs.

Even in the case of the long hole formation, the preparation time (t ₃ ) and the waiting time (t _j ) can not be eliminated. Furthermore, it may take extra time for the length of the long hole. However, once the long hole is penetrated by the preparation time (t ₃ ), it is considered that the operation time (t ₄ ) for expanding to a predetermined rectangular shape is sufficient. Therefore, as can be seen from the comparison between the upper and lower portions in FIG. 4, in the formation of the elongated holes on the lower portion side, the cumulative amount of the preparation time (t ₃ ) is relatively reduced compared to the upper portion. From this result, when obtaining the same amount of open area, the total amount of preparation time (t ₃ ) decreases, leading to time reduction. In addition, since the irradiation position frequently changes on the upper side, a large amount of waiting time (t _i ) is accumulated. On the other hand, since long holes are formed on the lower side, the number of changes in the irradiation position is smaller than on the upper side, and the cumulative amount of waiting time (t _j ) is generally small. From these comparisons, it can be said that the number of treatments per hour (the number of products produced) increases. According to the inventor's trial, the number of productions per hour increased approximately 1.5 times. As described above, the manufacturing method according to the long hole of the present application has a great advantage that the drilling operation time can be shortened compared with the circular hole shape, the operation efficiency is improved, and the production amount is increased.

  FIG. 5 is an overall perspective view of a lid 10x according to another embodiment. In the illustrated lid portion 10x, a concave portion 30 is formed in the lid surface portion 11x, and a long exhaust hole group 20 including a plurality of long exhaust holes 21 is bored in the concave portion 30. Unlike in FIGS. 1 and 2, the lid surface upper peripheral wall portion 35 is omitted. As can be seen from the lid surface 11x of FIG. 4, the shape of the lid surface 11x can be simplified. In other words, there are fewer structural restrictions on food containers, which is effective in reducing material costs.

  Each plan view of FIG. 6 shows another embodiment of the exhaust long hole group formed in the lid 10 (lid surface 11). The exhaust long hole group 20a in FIG. 6A is disposed in such a manner that the direction of each exhaust long hole 21 is gradually inclined. The illustrated concave portion 30a is rectangular. The exhaust long hole group 20 b of (b) is formed to have a substantially circular shape by forming the long exhaust hole 21. The illustrated concave portion 30b is circular. The exhaust long hole group 20c of (c) is formed in a shape imitating the letter "A" of the alphabet by drilling the long exhaust hole 21. The illustrated concave portion 30c has a rectangular shape. That is, the exhaust long hole group is configured as a planar figure. Planar figures include not only figures but also letters and symbols.

  The shape and direction of the planar figure of the elongated exhaust hole group are freely controlled by the setting at the time of laser beam irradiation. For this reason, restrictions such as a U-shape or a V-shape such as a tongue-shaped opening by a conventional cut are eliminated. By the plan figure of the exhaust long hole group formed by drilling the long exhaust hole, various information such as the manufacturer's and seller's trademarks, marks, logos and even the date of manufacture can be displayed through the exhaust long hole group It becomes. The arrangement of the elongated exhaust holes may be one or more than one on the lid surface of the lid. This is properly defined by the design of the food container.

  As described above, considering the size of the elongated exhaust hole in the food container (microwave oven heated food container) of the present invention, since it is extremely fine, it is possible to effectively suppress the entry of foreign matter such as insects and the like. . Therefore, in the food container of the present invention, a member such as a film covering or excreting a hole responsible for the exhaust of a lid found in a conventional container can be omitted. Therefore, the food container of the present invention can contribute to the reduction of the cost of packaging materials without the need for time-consuming operations such as microwave oven heating or opening at the time of heating. By considering the total open area of the elongated exhaust holes, the food container of the present invention is an extremely suitable packaging material that can cope with the amount of water vapor generated from various types of food. Furthermore, since various exhaust long hole groups can be formed depending on the arrangement of the exhaust long holes, in addition to the restriction of the shape design of the lid portion being reduced, the freedom of the shape of the long exhaust hole group itself is also enhanced.

[Preparation of container for microwave oven heating food]
The container for microwave oven heating food was an article consisting of a combination of a container body and a lid. The said "preparation of the container for microwave oven heating foodstuffs" assumed packaging of food with a large quantity. For the lid portion, a sheet material of heat resistant biaxially oriented polystyrene (heat resistant OPS) resin was used. This was processed into a disk-like lid by vacuum forming. The maximum diameter of the lid was about 175 mm, and the maximum diameter of the lid was about 135 mm. The material thickness of the lid portion was 0.3 mm. A heat-resistant expanded polystyrene sheet material (polypropylene film adherend) was used for the container body. The resultant was vacuum-formed into a bowl-like (pot-like or bowl-like) container body with a circular cross-section. The opening diameter (inner diameter) of the container body was about 160 mm and the depth was 70 mm, and the internal volume of the container body (food-containable volume) was about 800 mL.

[Formation of exhaust long holes]
At the time of formation of the elongated elongated holes, using a known carbon dioxide gas laser irradiation apparatus generally used in the resin processing field, nine types of exhausted gases different in size and number with respect to the central portion of the lid obtained by the above molding A long hole group was formed, and Examples 1 to 9 were produced (see Tables 1 and 2). In Tables 1 and 2, the size of the elongated exhaust hole (measured value) {width (mm), length (mm)} in order from the top, the configuration of the elongated exhaust hole group {arrangement of the elongated exhaust hole (horizontal x vertical) , The number of exhaust long holes (pieces)}, the opening area {per exhaust long hole (mm ² ), total opening area (mm ² )}.

  For reference, FIG. 7 is a photograph of the exhaust long hole group of the lid of the sixth embodiment. FIG. 8 is an enlarged photograph (magnification 50 times) of each exhaust long hole constituting the long exhaust hole group. The upper part of FIG. 8 is the long exhaust hole of the first embodiment, and the lower part of the same drawing is the long exhaust hole of the sixth embodiment. As can be seen from the drawing, the elongated exhaust hole had a long rectangular shape with rounded ends. In addition, the numerical value of the width and the length of the elongated exhaust hole was a simple average of the numerical values obtained by measuring the elongated exhaust hole in each example. Further, in the calculation of the aperture area, the rounded portion shape of the both end portions can be ignored, and it is regarded as a rectangular shape and is the product of the “maximum width” and the “maximum length”.

[Microwave heating test of food]
The types of food actually sold are quite diverse. Therefore, the inventors selected "curry udon" as a food having a large amount of water and a long time required for microwave heating. The same amount (about 620 g in total) of the curry udon was accommodated in any of the container main body portions, and the lid portions (Examples 1 to 9) of the preparation were properly fitted. And it used for the heating test using the high output type microwave oven introduced into the convenience store etc. The heating condition in the microwave oven was set to an output of 1600 W in order to obtain a high heating load condition in which the output is higher than that of the commonly used 1500 W. The microwave oven heating time was made into 2 minutes or more on the said output conditions, and it cut off to 2 minutes and 30 seconds as an upper limit. Then, after 2 minutes, it was observed whether or not the lid portion fitted with the container body portion was detached by the water vapor pressure generated internally.

[Results and discussion of microwave oven heating test]
With respect to the lids of Examples 1 to 9, the lid did not come off the container main body at all when 2 minutes of microwave heating had elapsed. FIG. 9 is a photograph obtained by photographing a state in which 2 minutes have elapsed using the lid of Example 6.

  As described above, the disclosed microwave heating test is a test in which the heating load is higher than the conditions usually performed. Even under the conditions, the exhaust long hole group of each example sufficiently exhibited the exhaust performance of the internally generated water vapor. In addition, the food used for the experiment also has a large amount of water and a large amount of water, and requires a large amount of heating time. Therefore, the good steam exhaust even under these severe conditions strongly affirms the effectiveness of the exhaust long hole of the present invention.

[About the size range of the exhaust long hole]
From the test results using the lids of Examples 1 to 9, the ranges for the exemplary elongated exhaust holes can be derived as follows. From Table 1 and Table 2 listed above, the minimum width of the elongated exhaust hole is Example 7. Therefore, the lower limit value of the width is set to 0.15 mm, preferably 0.3 mm, in consideration of the processing accuracy and the number of the irradiation apparatus. Since the maximum width is Example 9, the upper limit is 1.0 mm. Although it is possible to raise the upper limit of the width, the upper limit is 1.0 mm from the viewpoint of preventing the contamination. Therefore, the range of the width of the elongated exhaust hole is 0.15 to 1.0 mm, preferably 0.3 to 0.5 mm.

  From Table 1 and Table 2, the minimum length of the exhaust long hole is Example 7. Therefore, in consideration of the processing accuracy and the number of the irradiation apparatus, the lower limit value of the length is set to 1 mm, preferably 4 mm in consideration of other examples. The maximum length was 12 mm from Example 4. Of course, it is also possible to make it longer. However, in consideration of securing the strength of the long exhaust hole portion and contamination and the like, 12 mm is the practical upper limit. Therefore, the length of the elongated exhaust hole is in the range of 1 to 12 mm, preferably 4 to 7 mm in consideration of the length of another embodiment.

Subsequently, for the sum of the open areas of the elongated exhaust holes (the sum of the open areas of all the elongated exhaust holes on the lid surface), it is possible to derive a range of approximately 35 to 65 mm ² from the test results in this example. it can. In addition to this result, the range of 0.3 to 100 mm ² , preferably 1 to 80 mm ² was specified in consideration of the variety of properties, capacity and the like of the food which is the content.

  As described above, the method for producing the container for microwave oven heating food of the present invention is a good steam exhaust and sealing instead of the steam exhaust using the conventional U-shaped or V-shaped tongue-shaped opening. It is possible to improve the stopping performance, exhaust the steam more efficiently, reduce the restrictions on the shape of the lid, reduce the material cost, and easily and quickly exhaust the lid surface A hole can be bored, and a method with excellent mass productivity can be provided. The provision of the elongated exhaust hole formed under appropriate conditions in the lid portion makes it possible to realize good exhaust of water vapor, which is extremely effective as a substitute for a packaging container for a microwave oven having an existing slit structure.

1 Container for food (container for microwave oven heating food)
DESCRIPTION OF SYMBOLS 10, 10x Lid part 11, 11x Lid surface part 15 Peripheral wall part 16 Lid adhesion wall part 20, 20a, 20b, 20c Exhaust long hole group 21 Exhaust long hole 30 Concave part 35 Lid surface upper peripheral wall part 100 Container main part 103 Inside of container 104 Barrel portion 105 Bottom portion 106 Opening peripheral wall 107 Opening step C Food Vp Steam

Claims (1)

A lid fitting container comprising: a container main body portion for containing food for microwave heating; and a lid portion made of a synthetic resin sheet to be fitted to the opening portion of the container main body portion,
Runisaishite obtain the lid portion forming the exhaust part for exhausting water vapor generated from the food contained in the container main body portion to the outside,
Laser beam irradiation is turned on at the lid surface portion, a through hole is formed by the passage of preparation time (t ₃ ), and it is expanded to a predetermined long hole shape by passage of the subsequent operation time (t ₄ ). By turning off
A manufacturing method of a container for microwave oven heating food, wherein a plurality of elongated exhaust holes having a width of 0.15 to 1.0 mm are formed to form an elongated exhaust hole group.

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