JP7543845B2 - Paper tray - Google Patents

Description

The present invention relates to paper trays. In particular, the present invention relates to paper trays formed using blanks based on paperboard, capable of storing frozen foods such as ice cream and powdered foods.

Paper trays are used in retail settings such as supermarkets and convenience stores as food packaging materials, for example. They come in a variety of forms, but because they are based on paper, they are widely used not only because of their cost advantage, but also as an environmentally friendly packaging material.

Also, various shapes are possible depending on the contents. A thermoplastic resin layer is applied to the surface of the paper base material used as a blank to impart water resistance, and the thermoplastic resin layer can be sealed to form a three-dimensional paper tray. A lid can also be sealed to seal the entire tray.

However, unlike plastic-based trays, which are made by assembling flat blanks based on paper, there are areas where the blanks overlap when assembled.

This part becomes thicker, creating a step between it and the surrounding area. When attempting to seal the paper tray, this step can become a seal defect, creating problems with sealing. In particular, when packaging liquid contents, there has been a demand for improvement as this can cause leakage problems, which are considered a serious defect in packaging materials.

For example, Patent Document 1 proposes a blank for a rectangular tray with edges, in which tongue pieces are provided at the four corners of the edge to join the edges in two directions. However, in this case, it is unavoidable that a step will be created at the joint of the tongue pieces, and there is a risk that the gaps caused by these steps will cause a lack of sealing and lead to leakage of the contents.

JP 2000-255546 A

The applicant filed patent applications No. 2020-59941 and No. 2020-165616 with the objective of solving this problem and providing a paper tray with good sealing properties and no step at the joint of the flange formed from the edge piece.

The present invention relates to an improvement of the inventions described in Patent Application Nos. 2020-59941 and 2020-165616, and aims to provide a paper tray that has no step at the joint of the flange formed from the edge piece, has good sealing properties, and can protect the contents from light by covering them with a light-blocking lid, even when the contents are ones that deteriorate when exposed to light.

That is, the invention described in claim 1 is a paper tray made of a paper blank,
The paper blank is made of a backing paper and a thermoplastic resin layer formed on both sides of the backing paper or on the surface that will become the inner surface of the tray.
The paper tray is composed of a bottom, side panels, and a rim piece.
The side panels rise up and surround the bottom to form a tray.
The edge piece is continuous with the upper end of the side panel and parallel to the bottom surface to surround the periphery of the tray to form a flange;
The backing paper constituting the blank has a corner portion of the tray where a portion between a side panel and an adjacent side panel is cut away, and a portion between an edge piece and an adjacent edge piece is cut away,
The thermoplastic resin layer is laminated on both sides of the mount or on the inner surface of the tray, including the portion where the mount has been cut away;
The side panels that surround the bottom are connected to the adjacent side panels by a thermoplastic resin layer in the area where the backing was cut away, and are sealed between the adjacent side panels.
Similarly, the edge pieces are sealed and connected to each other by the thermoplastic resin layer at the cut-out portion of the backing paper to form a tray.
When the bottom surface has a shape of a regular octagon stretched vertically and horizontally, and the side panels connected to the four non-stretched sides are called corner panels and the edge pieces continuing from the corner panels are called corner edge pieces, and the side panels connected to the other sides of the bottom surface are called main side panels and the edge pieces continuing from the main side panels are called main edge pieces, the main side panels are folded so that they are overlapped on the corner panels and the main edge pieces are overlapped on the corner edge pieces, and the side end faces of the main edge pieces are butted together and arranged without overlapping,
When the length of the base of the corner plate is C, the distance between the tip of the corner plate and the main edge piece adjacent to the corner plate is f, and the thickness of the backing paper is t, f>C/2+2t;
The paper tray is characterized in that the backing paper has light-blocking properties.

Next, the invention described in claim 2 is a paper tray as described in claim 1, characterized in that the thermoplastic resin layer is made of one or more resins selected from the group consisting of polyethylene resin, polypropylene resin, polyethylene terephthalate resin, and polybutylene terephthalate resin.

Next, the invention described in claim 3 is the paper tray described in claim 1 or 2 , characterized in that the backing paper is made by papermaking with a black or dark color pigment blended therein.

Next, the invention described in claim 4 is a paper tray described in any of claims 1 to 3, characterized in that the backing paper has a light-shielding layer in its layer structure, and this light-shielding layer is made of a light-absorbing layer.

Next, the invention described in claim 5 is a paper tray described in any of claims 1 to 3, characterized in that the backing paper has a light-shielding layer in its layer structure, and this light-shielding layer is made of a light-reflective layer.

According to the present invention, it is possible to provide a paper tray with good sealing performance, without any step at the joint of the flange formed from the edge piece.

The present invention is a paper tray made of paper blanks. The paper tray is composed of a bottom surface, side panels, and edge pieces. The side panels rise up and surround the bottom surface to form the tray, making the paper tray more environmentally friendly, highly water-resistant, and easy to form into a tray from a flat blank.

In addition, in the present invention, the edge pieces are continuous with the upper ends of the side panels and are parallel to the bottom surface, surrounding the tray to form a flange that surrounds the periphery of the paper tray. Since there are no steps in the flange due to overlapping blanks, it is easy to seal the lid material, making it possible to produce a paper tray with better airtightness.

In other words, the backing paper that makes up the blanks is cut out at the corners of the tray so that there is no overlap between adjacent side panels when the side panels are erected, and the edge pieces are also cut out so that there is no overlap between adjacent edge pieces when the entire edge piece is formed. This makes it possible to eliminate overlapping areas between blanks when assembling the blanks into a paper tray to form a three-dimensional object.

The thermoplastic resin layer is laminated on both sides of the backing or on the inner surface of the tray, including the area where the backing has been cut out, and the side panels that rise up around the bottom are sealed and connected to the adjacent side panels by the thermoplastic resin layer in the area where the backing has been cut out. Similarly, the edge pieces are sealed and connected to the adjacent edge pieces by the thermoplastic resin layer in the area where the backing has been cut out to form the tray, which makes it possible to assemble the paper tray without the blanks overlapping, and the lack of overlapping ensures flatness, so that even when a lid is attached to the paper tray and sealed to the flange, the paper tray can be made to have good sealing properties.

In addition, the backing that makes up the blanks contains a light-blocking layer in its layer structure, so even if the contents stored in the container are ones that deteriorate when exposed to light, the contents can be protected from light by covering them with a light-blocking lid.

According to the invention described in claim 2 , the thermoplastic resin layer is made of one or more of polyethylene resin, polypropylene resin, polyethylene terephthalate resin, and polybutylene terephthalate resin, which is more suitable as a sealant when assembling paper trays and allows the sealant to be designed according to the application of the paper tray. In particular, when polyethylene terephthalate resin or polybutylene terephthalate is selected, a paper tray with better heat resistance can be realized.

FIG. 1 is a schematic perspective view for explaining one embodiment of a paper tray according to the present invention. FIG. 2 shows a backing portion of one embodiment of a blank constituting a paper tray according to the present invention, with FIG. 2(a) being an explanatory planar development schematic view, and FIG. 2(b) being an explanatory sectional view. Figure 3 is a schematic planar development diagram of a backing sheet to explain that, at a corner of one embodiment of a paper tray according to the present invention, when the side panels are raised to form a paper tray, the backing sheet between the side panels and adjacent side panels is cut out so that the side panels of the backing sheet do not overlap with the adjacent side panels, and that when the paper tray is formed, the backing sheet between the edge pieces and adjacent edge pieces is cut out so that the edge pieces do not overlap with the adjacent edge pieces. FIG. 4 is a schematic plan view illustrating a window cutout portion of a backing paper in one embodiment of the paper tray according to the present invention. FIG. 5 is a schematic plan view illustrating a blank having thermoplastic resin provided thereon, including the window cutout portion of the backing, in one embodiment of the paper tray according to the present invention. Figure 6 is a schematic plan view illustrating the state of a paper tray according to one embodiment of the present invention, in which thermoplastic resin is applied to both the front and back surfaces of the backing paper or the inner surface of the tray, after which punching is completed and the blank is completed. FIG. 7 is a schematic plan view of a second embodiment of a paper tray according to the present invention. FIG. 8 is a schematic plan view of a blank sheet used for the paper tray shown in FIG. FIG. 9 is an enlarged view of a corner portion of a blank sheet used for the paper tray shown in FIG. 8, and is an explanatory diagram of the length C of the base side of the corner plate and the distance f between the tip of the corner plate and the tip of the flange portion. FIG. 10 is an enlarged view of a corner portion of a blank sheet used in a third embodiment of the paper tray according to the present invention. FIG. 11 is an enlarged explanatory plan view showing a corner portion of the blank sheet shown in FIG. 10 after it has been formed into a tray-type paper container.

The present invention will now be described in more detail with reference to the drawings. However, the present invention is not limited to the examples shown here. The present invention is defined by the claims.

Figure 1 is a schematic perspective view for explaining one embodiment of a paper tray according to the present invention.

The present invention is a paper tray 100 formed from a paper blank 40. As shown in the perspective schematic diagram of one embodiment in Figure 1, it has a bottom plate 1 and is surrounded by side plates 2, and at the upper end of the side plate 2, an edge piece 3 is formed that is continuous with the side plate 2 and parallel to the bottom surface 1.

In this example, the bottom surface 1 has a shape obtained by stretching a regular octagon in the vertical and horizontal directions, and therefore, in Fig. 1, the side panels 2 connected to the four non-stretched sides are distinguished from the side panels 2 connected to the other sides of the bottom surface, and the side panels 2 connected to the four non-stretched sides are called "corner panels" and given the reference number _22. On the other hand, the side panel 22 connected to the other side is called "main side panel" and given the reference number _21. Also, the edge piece 3 connected to the corner panel ₂₂ is called "corner edge piece" and given the reference number ₃₂ , and the edge piece 3 connected to the main side panel ₂₁ is called "main edge piece" and given the reference number _31. The same applies to the following explanation.

The edge pieces 3 surround the periphery of the paper tray 100 to form a flange 4. Therefore, as can be seen from Fig. 1, the flange 4 is octagonal and is composed of eight edge pieces 3. Of these eight edge pieces 3, four are main edge pieces ₃₁ , and the remaining four are corner edge pieces _32. These main edge pieces ₃₁ and corner edge pieces ₃₂ are arranged alternately in the circumferential direction, and the side end faces of the main edge pieces ₃₁ and the side end faces of the corner edge pieces ₃₂ are butted against each other, so that there is no gap or step between them. Therefore, the flange 4 is flat all around and is flush with the surface.

In the example shown in Fig. 1, the bottom plate 1 is octagonal as described above, and therefore there are eight side plates 2. Of these eight side plates 2, four are main side plates ₂₁ , and the remaining four are corner plates _22. These main side plates ₂₁ and corner plates ₂₂ are arranged alternately in the circumferential direction. The main edge piece ₃₁ is connected to the main side plate ₂₁ , and the corner edge piece ₃₂ is connected to the inner plate ₂₂ .

As shown in Figure 1, the three-dimensional paper tray 100 with the side panel 2 standing upright can be used as an octagonal container for storing contents.

In the present invention, the paper blank 40 is composed of a backing 20 and a thermoplastic resin layer 30 formed on both sides of the backing 20 or on the surface that will become the inside of the tray 100, and the three-dimensional formation of the paper tray 100 can be performed by sealing and adhering the thermoplastic resin layer 30. In addition, since the blank 40 is covered on both sides of the front and back or on the surface that will become the inside of the tray 100 with the thermoplastic resin layer 30, it is possible to impart excellent water resistance to the paper tray 100.

The edge piece 3 formed as the flange 4 of the paper tray 100 can be used to seal the lid material to this portion, sealing the entire paper tray 100. As mentioned above, the flange 4 is flush and flat all around, so it is possible to seal the lid material without any gaps.

This paper tray 100 is made of paper-based materials, making it an excellent environmentally friendly packaging material, and can be made airtight if necessary, making it a highly convenient paper tray 100 that can be used in a wide range of applications.

In addition, the present invention can eliminate the overlap of blanks 40 when forming a solid shape, which has traditionally been a drawback of paper trays 100. In particular, it is possible to eliminate the overlap of the flange 4 portion that surrounds the periphery of the paper tray 100, which is formed by edge pieces 3, and make it flat. Therefore, it is possible to make a paper tray 100 with excellent sealing properties.

As mentioned above, the blank 40 used to manufacture the paper tray 100 is composed of a backing 20 and a thermoplastic resin layer 30 formed on both sides of the backing 20 or on the surface that will become the inside of the tray 100. Figure 2 shows the backing 20 and the thermoplastic resin layer 30, with Figure 2(a) being a schematic planar development diagram for explaining the shape of the backing 20, and Figure 2(b) being a cross-sectional diagram for explaining the layer structure of the backing 20.

As shown in the planar development schematic diagram 9 of the example shown in FIG. 2(a), the backing paper 20 of the paper tray 100 has side panels 2 that rise around the bottom surface 1, and the side panels 2 have edge pieces 3 that are continuous with the upper ends of the side panels 2, and when the paper tray 100 is made, the edge pieces 3 form a flange that is parallel to the bottom surface 1.

In the embodiment shown in Fig. 2(a), the bottom plate 1 has a quadrilateral shape with the four corners 10 chamfered. Therefore, the bottom plate 1 is octagonal and has one side, and the side plate 2 stands up surrounding this octagonal bottom plate 1, so this side plate 2 has eight sides. Also, the edge piece 3 is connected to the upper end of each side plate 2, so it also has eight sides.

In addition, in FIG. 2(a), the fold line 5 between the bottom surface 1 and the side panel 2 is a valley fold, and the fold line 6 between the side panel 2 and the edge piece 3 is a mountain fold, so that the paper tray 100 rises up toward the front side of FIG. 2(a) to become three-dimensional.

At this time, unlike the planar development view of the conventional blanks 40, a V-shaped cut-out portion 11 is provided so that the blanks 40 do not overlap when made into a three-dimensional object. This cut-out portion 11 is cut out between the side panels 2 and adjacent side panels 2 in the backing paper of the corners 10 of the paper tray 100 so that the side panels 2 do not overlap when the side panels 2 are raised to form the paper tray 100, and is also cut out between the edge pieces 3 and adjacent edge pieces 3 so that the edge pieces 3 do not overlap when the paper tray 100 is formed.

Therefore, when the fold line 5 between the bottom surface 1 and the side panel 2 is folded in a valley shape to raise the side panel 2, the V-shaped cut-out portion between the side panels 2 is closed, and the side panels 2 become continuous with each other.

In addition, if the fold line 6 between the side panel 2 and the edge piece 3 is folded in a mountain fold to make the edge piece 3 parallel to the bottom surface 1, the edge pieces 3 will also be continuous with each other to form a flange 4 that surrounds the periphery of the paper tray 100.

When the paper tray 100 is formed into a three-dimensional shape, the edge piece 3 surrounds the periphery of the paper tray 100 and forms a horizontal surface, so it is possible to seal the lid material to the edge piece 3 and seal the entire paper tray 100.

The mount 20 must have light-blocking properties. Because the mount 20 has light-blocking properties, even if the contents stored therein are ones that deteriorate when exposed to light, the contents can be protected from light by covering them with a light-blocking lid.

Such a light-shielding backing 20 may be, for example, a paper layer made by blending a black or dark colored pigment. Carbon black is a suitable pigment. An example of such a backing 20 made by blending a black or dark colored pigment is "Zebra C Acid-Resistant Cup Base Paper" manufactured by Nippon Paper Crecia Co., Ltd.

Also, as shown in FIG. 2(b), the layer structure may include a light-shielding layer. The mount 20 shown in FIG. 2(b) is constructed by laminating two paper layers 20a and 20c made of paper fibers with a light-shielding layer 20b in between.

The light-shielding layer 20b may have light-absorbing properties, absorbing incident light and preventing its transmission, or it may have light-reflecting properties, reflecting incident light and preventing its transmission.

As described above, the light-absorbing light-shielding layer 20b can be a paper containing black or dark pigments. It can also be a black or dark printed layer, or a black or dark colored plastic film.

Examples of the light-reflective light-shielding layer 20b include metal foil or a metal-deposited film. For example, a deposition film in which an aluminum deposition film is formed on a plastic film can be used as the light-shielding layer 20b.

Next, FIG. 3 is a schematic planar development diagram of the backing 20 to explain that, at the corners of one embodiment of the paper tray according to the present invention, when the side panel 2 is raised to form the paper tray 100, the backing 20 between the side panel 2 and the adjacent side panel 2 is cut out so that the side panel 2 of the backing 20 does not overlap with the adjacent side panel 2, and that when the paper tray 100 is formed, the backing 20 between the edge piece 3 and the adjacent edge piece 3 is cut out so that the edge piece 3 does not overlap with the adjacent edge piece 3.

As mentioned above, in the present invention, in the backing 20 forming the blank 40, the backing 20 between adjacent side panels 2 is cut out so that the side panels 2 do not overlap when the side panels 2 are raised to form the paper tray 100, and the backing 20 between adjacent edge pieces 3 is also cut out.

In the example shown in FIG. 3, the cut out portions 11 in the mount 20 are punched out in pairs close to each other to form one window cutout 12, forming four window cutouts 12 at the four corners of the mount 20.

In Figure 3, the planar development of the blank 40 is shown with dashed lines to make it easier to understand the positional relationship between the window cutout 12 and the side panel 2 and edge piece 3.

Figure 4 is a schematic plan view illustrating the window cutout portion of the backing paper 20 in one embodiment of the paper tray 100 according to the present invention.

As mentioned above, the window cutouts 12 shown in FIG. 3 are located at the four corners of the mount 20. The relationship between the window cutouts 12 for providing the cut-out portions 11 and the mount 20 is as shown in FIG. 4.

The blank 40 for the paper tray 100 according to the present invention is obtained by providing a thermoplastic resin layer 30 on both the front and back sides of the backing paper 20 provided with the window cutout 12 in this manner, or on the side that will become the inside of the tray 100. That is, in the present invention, the thermoplastic resin layer 30 is laminated on the front and back sides of the backing paper 20, or on the side that will become the inside of the tray 100, including the window cutout 12 of the backing paper 20 (see FIG. 5).

In this way, by laminating the backing paper 20 and the thermoplastic resin layer 30 and then punching out the blanks 40 for the paper tray 100, it is possible to more accurately and productively produce the blanks 40 for the paper tray 100 according to the present invention.

To create the blank 40, the four corners are separated and removed from the backing 20 after lamination of the thermoplastic resin 30 shown in Figure 4.

Figure 6 is a schematic plan view of one embodiment of the paper tray 100 according to the present invention, showing the state in which the blank 40 is completed after the thermoplastic resin 30 is applied to both the front and back sides of the backing 20 or the inner surface of the tray 100 and punching is completed.

In the blank 40 for the paper tray 100 according to the present invention, the backing 20 is cut as shown in the planar development diagram 9 in FIG. 2, and a thermoplastic resin layer 30 is provided on both the front and back surfaces or on the surface that will become the inside of the tray 100.

The thermoplastic resin layer 30 covers not only the mount 20 but also the cut-out portion 11 that is provided so that there is no overlap between the mounts 20 of the blanks 40. This portion forms a window cutout portion 12 in the mount 20, but only the thermoplastic resin layer 30 is laminated on both the front and back sides or on the surface that will become the inside of the tray.

The blank 40 shown in FIG. 6 has a bottom surface 1 at its center, and side panels 2 that rise up around the bottom surface 1 have edge pieces 3 formed at the upper ends of the side panels 2 that are continuous with the bottom surface 1 and are parallel to the bottom surface 1. In FIG. 6, the fold line 5 between the bottom surface 1 and the side panels 2 is a valley fold, and the fold line 6 between the side panels 2 and the edge pieces 3 is a mountain fold, so that the paper tray 100 rises to the front side of FIG. 6 and becomes three-dimensional.

At this time, at the corners 10 of the paper tray 100, the side panel 2 and the adjacent side panel 2 can be sealed by the thermoplastic resin layer 30 in the portion where the backing 20 has been cut away, and similarly, the edge piece 3 and the adjacent edge piece 3 can also be sealed by the thermoplastic resin layer 30 in the portion where the backing 20 has been cut away. In this way, the paper tray 100 is formed by sealing between the side panel 2 and the adjacent side panel 2, and between the edge piece 3 and the adjacent edge piece 3. For example, heat sealing can be used for this sealing.

The thermoplastic resin layers 30 are laminated so that the thermoplastic resin layers 30 face each other, and are bonded to each other by applying heat and pressure to heat seal, thereby enabling the layers to be bonded to each other.

Thermoplastic resin layer 30 is generally made of polyolefin-based thermoplastic resins. Specifically, ethylene-based resins such as low-density polyethylene resin (LDPE), medium-density polyethylene resin (MDPE), linear low-density polyethylene resin (LLDPE), ethylene-vinyl acetate copolymer (EVA), ethylene-α-olefin copolymer, and ethylene-methacrylic acid resin copolymer, as well as blends of polyethylene and polybutene, and polypropylene-based resins such as homopolypropylene resin (PP), propylene-ethylene random copolymer, propylene-ethylene block copolymer, and propylene-α-olefin copolymer can be used.

To form the thermoplastic resin layer 30, a film of molten resin can be formed using an extruder or the like to form a layer on the mount 20. Alternatively, the thermoplastic resin layer 30 can be formed on both sides or one side of the mount 20 by laminating a material that has already been formed into a film.

For this thermoplastic resin layer 30, in addition to the aforementioned polyethylene resin and polypropylene resin, one or more of polyethylene terephthalate resin and polybutylene terephthalate resin can be used. These can be appropriately selected and used depending on the application and required quality of the paper tray 100.

In particular, when polyethylene terephthalate resin or polybutylene terephthalate resin is used, the paper tray 100 has high heat resistance, for example, when used in applications involving microwave heating.

In this way, the present invention makes it possible to provide paper trays with good sealing properties, without any step at the joint of the flange formed from the edge piece, and because the backing paper contains a light-blocking layer in its layer structure, even when contents that deteriorate when exposed to light are placed inside, the contents can be protected from light by covering them with a light-blocking lid.

In the above example, the side end face of the main edge piece ₃₁ and the side end face of the corner edge piece ₃₂ are butted together so that there is no gap or step between them, but it is also possible to butt the side end faces of the main edge pieces ₃₁ together to form a flange 4 without a step.

Fig. 7 is a schematic plan view of a paper tray 200 in which the side end faces of the main edge pieces ₃₁ are butted together to form a flange 4 without a step. Fig. 8 is a schematic plan view of a blank sheet used in the paper tray 200.

In this example, the corner plate ₂₂ is rectangular, while the main side plate ₂₁ is inverted trapezoidal. When assembling the paper tray 200 from the blank sheet, the blank sheet is folded to overlap the main side plate ₂₁ with the corner plate ₂₂ , and the main edge piece ₃₁ with the corner edge piece ₃₂ , and the side end faces of the adjacent main edge pieces ₃₁ are butted against each other so that there is no step between the main edge pieces ₃₁ and _31. The flange 4 of the paper tray 200 assembled in this way is also flat and flush all around. This allows the lid to be sealed without any gaps.

Incidentally, the flange 4 of the paper tray 200 thus assembled forms a flat surface without any steps, but gaps may occur between the main edge pieces 3 ₁ and 3 _1. Fig. 9 is an enlarged view of the corner portion of the blank sheet, and is an explanatory diagram of the length C of the bottom side of the corner plate 2 ₂ and the distance f between the tip of the corner plate 2 ₂ and the tip of the main edge piece 3 ₁ adjacent to this corner plate 2 _2. Regarding the value of f, geometrically, when f = C/2, the side end faces of the main edge pieces 3 ₁ should fit closely together and no gaps should occur, but in reality, it has been found that gaps occur when f = C/2 due to the thickness of the backing sheet 20 and the thickness of the thermoplastic resin layer 30. Even if gaps occur, they do not lead to the occurrence of pinholes as long as they are within a certain range.

If an excessive gap occurs between the main edge pieces ₃₁ , it will result in poor sealing when sealing the lid material. Therefore, by making f>C/2, the side end faces of the main edge pieces ₃₁ do not overlap on the corner plate ₂₂ during molding, and the gap is within the allowable range, allowing for safe molding.

Furthermore, if the thickness of the backing 20 is t, then by making f>C/2+2t, the gap will be further reduced, further increasing safety.

Next, FIG. 10 is an enlarged view of a corner portion of a blank sheet in a third embodiment of the paper tray according to the present invention, and is an explanatory diagram of a notch 11x. Also, FIG. 11 is an explanatory plan view showing the blank sheet shown in FIG. 10 after it has been formed into a paper tray 300.

In this example, the mount 20 is provided with cutouts 11x at both ends of the main edge piece _31. This has the effect of removing in advance the portion of the mount 20 that is most likely to overlap, making it more difficult for the main edge pieces ₃₁ to overlap each other. Since the corner edge piece ₃₂ overlaps the inside of this cutout 11x, no light is allowed to enter through this cutout 11x. Therefore, the contents can be protected from light by covering the paper tray 300 with a light-shielding lid.

The same applies when a notch is provided in the main side panel ₂₁ instead of the main edge piece ₃₁ .

REFERENCE SIGNS LIST 1: bottom plate 2: side plate 2 ₁ : main side plate 2 ₂ : corner plate 3: edge piece 3 ₁ : main edge piece 3 ₂ : corner edge piece 4: flange 5: fold line 6: fold line 10: corner 11: cut-out portion 11x: cutout 12: window cut-out portion 20: backing 20a: paper layer 20b: light-shielding layer 20c: paper layer 30: thermoplastic resin layer 40: blank 100: paper tray 200: paper tray 300: paper tray

Claims (5)

A paper tray made of a paper blank,
The paper blank is made of a backing paper and a thermoplastic resin layer formed on both sides of the backing paper or on the surface that will become the inner surface of the tray.
The paper tray is composed of a bottom, side panels, and a rim piece.
The side panels rise up and surround the bottom to form a tray.
The edge piece is continuous with the upper end of the side panel and parallel to the bottom surface to surround the periphery of the tray to form a flange;
The backing paper constituting the blank has a corner portion of the tray where a portion between a side panel and an adjacent side panel is cut away, and a portion between an edge piece and an adjacent edge piece is cut away,
The thermoplastic resin layer is laminated on both sides of the mount or on the inner surface of the tray, including the portion where the mount has been cut away;
The side panels that surround the bottom are connected to the adjacent side panels by a thermoplastic resin layer in the area where the backing was cut away, and are sealed between the adjacent side panels.
Similarly, the edge pieces are sealed and connected to each other by the thermoplastic resin layer at the cut-out portion of the backing paper to form a tray.
When the bottom surface has a shape of a regular octagon stretched vertically and horizontally, and the side panels connected to the four non-stretched sides are called corner panels and the edge pieces continuing from the corner panels are called corner edge pieces, and the side panels connected to the other sides of the bottom surface are called main side panels and the edge pieces continuing from the main side panels are called main edge pieces, the main side panels are folded so that they are overlapped on the corner panels and the main edge pieces are overlapped on the corner edge pieces, and the side end faces of the main edge pieces are butted together and arranged without overlapping,
When the length of the base of the corner plate is C, the distance between the tip of the corner plate and the main edge piece adjacent to the corner plate is f, and the thickness of the backing paper is t, f>C/2+2t;
A paper tray, characterized in that the backing paper has light-blocking properties. The paper tray according to claim 1, characterized in that the thermoplastic resin layer is made of one or more resins selected from the group consisting of polyethylene resin, polypropylene resin, polyethylene terephthalate resin, and polybutylene terephthalate resin. 3. The paper tray according to claim 1, wherein the backing paper is made by papermaking with a black or dark color pigment blended therein. 4. The paper tray according to claim 1, wherein the backing sheet has a light-shielding layer in its layer structure, the light-shielding layer being made of a light-absorbing layer. 4. The paper tray according to claim 1, wherein the backing sheet has a light-shielding layer in its layer structure, the light-shielding layer being made of a light-reflective layer.

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