JP7278580B2 - tray - Google Patents

Description

The present invention relates to trays.

Conventionally, a metal tray is used for cooking in an oven. Metal trays have excellent heat resistance, so they are less likely to deform even after repeated heating and cooking. However, metal trays have high thermal conductivity and are heavy, so there is a problem that the user is likely to get burned. Also, food can stick to metal trays.

In recent years, not only metal trays but also resin trays have been developed. A tray made of a resin having a high melting point is not easily deformed even when heated to a temperature below the melting point. In addition, since resin trays have low thermal conductivity, they are less likely to cause burns to the user.

However, when resin trays are repeatedly used as oven attachments in a high temperature range exceeding 200° C., it may be difficult to maintain their shape due to the property of resin to soften with temperature. Therefore, in such applications, composite materials (also called fabrics) with resins reinforced with high heat-resistant fibers such as glass fibers are used. Conventionally, fabrics are formed into three-dimensional shapes without drawing. In this molding, for example, a portion of the fabric is folded to form a tray having a bottomed rectangular tube shape with a bottom and sides. When a portion of the fabric is folded to form a square tube shape with a bottom, a seam is formed inside the square tube, for example, at the boundary between two adjacent sides. The position of the seam is not limited to this location, but if there is a seam on the inner surface of the tray, food may enter the seam, which is not hygienic.

JP 2018-079596 A JP 2017-178398 A

SUMMARY OF THE INVENTION It is an object of the present invention to provide a seamless tray which is excellent in heat resistance and releasability and into which food may enter.

According to one aspect of the present invention, there is provided a tray comprising a bottom portion and side portions extending in a height direction from the bottom portion, wherein the bottom portion and the side portions are made of single-layered fabric. The fabric includes a woven fabric and fluororesin layers formed on both sides of the woven fabric, and the first radius of curvature defined by the inner surface of the bottom portion and the inner surface of the side portion is 1.5 mm The outer edge of the bottom portion is a polygon having three or more corners, and the side portion has a plurality of sidewalls corresponding to the number of the three or more corners, and two adjacent A second radius of curvature defined by the inner surface of one of the side walls and the other side wall of the side walls is 5 mm or more .

ADVANTAGE OF THE INVENTION According to this invention, while being excellent in heat resistance and releasability, a seamless tray can be provided.

The perspective view which shows an example of the tray which concerns on embodiment. FIG. 2 is a plan view showing the tray shown in FIG. 1; FIG. 2 is a cross-sectional view showing the tray shown in FIG. 1; Sectional drawing which shows the other example of the tray which concerns on embodiment. FIG. 4 is an enlarged cross-sectional view showing an enlarged portion A of FIG. 3 ; Sectional drawing which shows roughly an example of the production line which concerns on an impregnation coating process. Sectional drawing which shows roughly 1 process of the manufacturing method of the tray which concerns on embodiment. Sectional drawing which shows roughly the other process of the manufacturing method of the tray which concerns on embodiment. Sectional drawing which shows roughly the other process of the manufacturing method of the tray which concerns on embodiment. Sectional drawing which shows roughly the other process of the manufacturing method of the tray which concerns on embodiment.

Conventionally, a resin tray made of the above fabric is three-dimensionally formed by, for example, cutting the fabric into a predetermined development shape, folding a part of the fabric, and heat-treating the cut fabric. The fabric contains a high heat-resistant fiber as a core material, and has a fluororesin layer on both sides thereof, and the fluororesin layer includes, for example, polytetrafluoroethylene (PTFE) and perfluoroalkoxyalkane (PFA). Because it is used, the tray has high heat resistance and is highly releasable from food. However, folding a portion of the fabric to form a three-dimensional tray results in overlapping portions of the fabric on at least a portion of the tray, for example, forming a seam around the portion. If a seam is formed, food may enter the seam when used as a tray for placing food. It is difficult to completely wash the food that has entered the seams of the tray.

The inventors of the present invention have developed a seamless three-dimensional fabric by drawing a fabric having a core material of high heat resistance fiber and fluororesin layers on both sides thereof so as to form a tray shape. Succeeded in forming a tray.

That is, the tray according to the embodiment includes a bottom portion and side portions extending from the bottom portion along the height direction. The bottom part and the side parts are made of a single layer fabric. The fabric includes a woven fabric and fluororesin layers formed on both sides of the woven fabric.

As used herein, "single layer structure" means that the fabric is not laminated in two or more layers and the fabrics are not spliced together. Since the bottom and side portions of the tray according to the embodiment are made of a single-layer fabric, the tray does not have a seam. In other words, there is no layered fabric on the bottom and sides of the tray.

Also, the fabric forming the tray includes a woven fabric and fluororesin layers formed on both sides of the woven fabric. That is, since the fluororesin layers are present on the inner and outer surfaces of the tray, the tray has excellent heat resistance and releasability.

Since the tray according to the embodiment has no seams, it is possible to prevent food from entering the seams. Therefore, it is hygienic even when the tray is reused. Furthermore, since the fluororesin layer is present on the inner surface of the tray, when food is placed on the tray and heated in an oven or the like, the food is less likely to stick to the surface of the tray. The tray according to the embodiment is also hygienically excellent in this respect.

The fluororesin layer may include a first fluororesin layer and a second fluororesin layer. That is, the fabric may include a woven fabric, a first fluororesin layer formed on the woven fabric, and a second fluororesin layer formed on the first fluororesin layer. The second fluororesin layer can have higher permeation resistance than the first fluororesin layer. The moisture vapor transmission rate of the fabric including the second fluororesin layer may be 25 g/m ² ·day·mm or less. This value is the measured value obtained under JIS K 7129-1 test condition 1 (temperature of transmission cell: 40 ° C., humidity of high humidity chamber: 100%, humidity of low humidity chamber: 10%). It is obtained by dividing by the thickness (mm).

When the fabric includes a woven fabric, a first fluororesin layer formed on the woven fabric, and a second fluororesin layer formed on the first fluororesin layer, when drawing the fabric In addition, cracks are less likely to occur in the resulting tray. This is considered to be due to the following reasons. First, since the first fluororesin layer exists in the gap between the warp and the weft that form the woven fabric (also referred to as the inside of the woven fabric) and on the surface of these threads, the first fluororesin layer It is fused to the woven fabric with sufficient peel strength. In addition, the second fluororesin layer is formed on the first fluororesin layer, and since these layers are layers that mainly contain fluororesin, they are compatible with each other and have good adhesion even at high temperatures. is high. Therefore, when the fabric is drawn, the woven fabric and the first fluororesin layer are less likely to separate, and the first fluororesin layer and the second fluororesin layer are less likely to separate. Therefore, the fabric can be stretched relatively flexibly in response to applied pressure without the woven fabric and each fluoroplastic layer delaminating from each other. As a result, cracks on the surface and inside of the tray obtained after processing can be reduced.

Hereinafter, trays according to embodiments will be described in detail with reference to the drawings.

1 is a perspective view showing an example of a tray according to an embodiment; FIG. 2 is a plan view showing the tray shown in FIG. 1. FIG. 3 is a cross-sectional view showing the tray shown in FIG. 1. FIG. 4 is an enlarged cross-sectional view showing an enlarged portion A of FIG. 3. FIG.

The tray 10 includes a bottom portion 11 having an outer edge 110, and side walls 12a, 12b, 12c and 12d extending from the outer edge 110 of the bottom portion 11 along the height direction. In this specification, the four side walls 12a, 12b, 12c, and 12d may be collectively referred to as the side surface portion 12. As shown in FIG. The bottom portion 11 and the side portion 12 can form, for example, a cylindrical shape with a bottom.

The shape of the outer edge 110 of the bottom portion 11 is not particularly limited. The shape of the outer edge 110 of the bottom portion 11 may be, for example, circular, elliptical, or polygonal with three or more corners. When the shape of the outer edge 110 of the bottom portion 11 is a polygon having three or more corners, the number of wall surfaces (side walls) of the side portion is the same as the number of corners of the outer edge 110 of the bottom portion 11 . That is, when the shape of the outer edge 110 of the bottom portion 11 is a polygon having three or more corners, the entire side portion is composed of a plurality of side walls corresponding to the number of three or more corners. FIG. 1 shows, as an example, the case where the outer edge 110 of the bottom portion 11 is rectangular. In this case, the tray has the shape of a rectangular cylinder with a bottom and four side walls.

As shown in FIGS. 1-3, the upper end 121 of the side portion 12 is open. The tray 10 may further comprise a flange portion 13 extending from the upper end 121 of the side portion 12, as shown in FIGS. 1-3. The flange portion 13 can be omitted. If the tray 10 is provided with a flange 13, the edge of the flange 13 is the edge of the fabric. On the other hand, if the tray 10 does not have the flange portion 13, for example, the upper end 121 of the side portion 12 is the edge of the fabric (not shown). The edge of the fabric is, for example, an exposed portion where the woven fabric and the fluororesin layer are cut, and there is a possibility that a very small gap exists between the woven fabric and the fluororesin layer. There is a possibility that the food may get into this small gap or moisture contained in the food may permeate. If the tray 10 is provided with the flange portion 13, it is possible to reduce the possibility that the food and the moisture contained in the food will seep into the edges of the fabric. Moreover, if the tray 10 is provided with the flange portion 13, the flange portion 13 can be grasped when carrying the heated tray 10, so that the tray 10 can be easily carried.

FIG. 4 is a cross-sectional view showing a tray 10 according to another example. The flange portion 13 may have a downward protrusion 130 . The downward projecting portion 130 extends along the height direction of the tray 10 at the edge of the flange portion 13 , for example, along the direction perpendicular to the in-plane direction of the bottom portion 11 . The downward projecting portion 130 may be provided along the entire periphery of the edge of the flange portion 13 . If the flange portion 13 has the downward projecting portion 130, for example, even if the tray 10 is subjected to heat cooking using an oven or the like, the entire tray 10 is less likely to be deformed, which is preferable.

FIG. 5 is an enlarged cross-sectional view showing a portion A of FIG. 3 in an enlarged manner. 1 to 5, including this FIG. 5, includes a woven fabric 3 and fluororesin layers 6 formed on both sides of the woven fabric 3. As shown in FIG. 1 to 5, the fluororesin layer 6 includes two layers, a first fluororesin layer 4 formed on the woven fabric and a second fluororesin layer 5 formed on the first fluororesin layer. .

The bottom portion 11 and the side portion 12 are made of a single layer fabric. In other words, the bottom part 11 and the side part 12 are formed from a continuous fabric and have no overlapping fabric. FIGS. 1 to 5 show the case where the flange portion 13 as well as the bottom portion 11 and the side portion 12 are made of single-layer fabric. That is, the bottom portion 11, the side portion 12 and the flange portion 13 are made of a continuous fabric. The details of the woven fabric and the fluororesin layer that constitute the fabric will be described later.

The bottom portion 11 has an inner surface facing the space surrounded by the side portions 12 and an outer surface on the opposite side of the inner surface. The side 12 has an inner surface facing the side 12 itself and an outer surface opposite the inner surface. For example, in FIGS. 1-4, sidewall 12a has an inner surface facing opposing sidewall 12c and an outer surface opposite the inner surface. Side walls 12b, 12c and 12d similarly have inner and outer surfaces. The flange portion 13 has an inner surface extending from the inner surface of the side portion 12 and an outer surface present on the opposite side of the inner surface.

The inner surface of the bottom portion 11 and the inner surface of the side portion 12 form an inner surface 14 of the tray 10 . The outer surface of the bottom portion 11 and the outer surface of the side portion 12 constitute the outer surface 15 of the tray. The inner surface 14 and outer surface 15 of tray 10 are seamless. The inner surface of the bottom portion 11 , the inner surface of the side portion 12 , and the inner surface of the flange portion 13 may constitute the inner surface 14 of the tray 10 . The outer surface of the bottom portion 11 , the outer surface of the side portion 12 , and the outer surface of the flange portion 13 may constitute the outer surface 15 of the tray 10 .

The “height direction” along which the side surface portion 12 extends from the bottom surface portion 11 may be a direction (90°) orthogonal to the inner surface of the bottom surface portion 11, or a direction inclined from the orthogonal direction. may This height direction may be a direction that is inclined, for example, within the range of 1° to 89° from the direction orthogonal to the inner surface of the bottom surface portion 11 . The height direction along which the side surface portion 12 extends from the bottom surface portion 11 can be appropriately changed according to the usage pattern of the tray 10 .

The radius of curvature defined by the inner surface of bottom surface portion 11 and the inner surface of side surface portion 12 may be 1.5 mm or more. This radius of curvature is also called the first radius of curvature. The first radius of curvature is, for example, the radius of curvature of the curved surface at the tip of the dashed arrow indicated by symbol R1 in the cross-sectional view shown in FIG. Although the upper limit of the first curvature radius is not particularly limited, it is, for example, 7 mm or less. The first radius of curvature is preferably in the range of 2mm to 3.5mm. If the first radius of curvature is excessively small, it may be difficult to wash the food adhering to the vicinity of the boundary between the inner surface of the bottom surface portion 11 and the inner surface of the side surface portion 12 . Moreover, when the tray 10 is manufactured by drawing, the fabric tends to crack and wrinkle, which is not preferable.

As shown in FIGS. 1 to 5, when the shape of the outer edge 110 of the bottom portion 11 has three or more corners, the tray 10 has a plurality of side walls corresponding to the number of corners. For two adjacent side walls, the radius of curvature defined by the inner surface of one side wall and the inner surface of the other side wall is 5 mm or more. This radius of curvature is also called a second radius of curvature. The second radius of curvature is, for example, the radius of curvature of the curved surface at the tip of the dashed arrow indicated by symbol R2 in the plan view shown in FIG. Although the upper limit of the second radius of curvature is not particularly limited, it is, for example, 30 mm or less. The second radius of curvature is preferably in the range of 7mm to 20mm. If the second radius of curvature is too small, it may become difficult to wash the food adhering to the corners of the inner surface of the tray. Moreover, when the tray 10 is manufactured by drawing, the fabric tends to crack and wrinkle, which is not preferable.

In one aspect, the second radius of curvature at a position facing the outer edge 110 of the bottom portion 11 is smaller than the second radius of curvature at a position away from the bottom portion 11 in the height direction. For example, the second radius of curvature defined between two sidewalls increases continuously along the height direction along which the sidewalls extend. In this case, for example, the second radius of curvature near the outer edge 110 of the bottom surface portion 11 is smaller than the second radius of curvature near the upper end 121 of the side surface portion 12 . The second radius of curvature near the outer edge 110 of the bottom surface portion 11 is, for example, within the range of 7 mm to 30 mm, preferably within the range of 7 mm to 20 mm. The second radius of curvature near the upper end 121 of the side surface portion 12 is, for example, within the range of 8 mm to 33 mm, preferably within the range of 8 mm to 23 mm. The vicinity of the outer edge 110 of the bottom surface portion 11 is defined as the distance from the inner surface of the bottom surface portion 11 to the upper end 121 of the side surface portion 12, which is the depth H of the tray (see also FIG. 3), as will be described later. It refers to a position at a height greater than 0% and less than or equal to 10%. On the other hand, the vicinity of the upper end 121 of the side portion 12 refers to a position at a height of 90% or more and less than 100% based on the depth H of the tray.

Both the first radius of curvature and the second radius of curvature can be measured using a CNC (Computer Numerical Control) image measuring machine or contour shape measuring machine. As the CNC image measuring machine, for example, NEXIV VMZ-R4540 manufactured by Nikon Corporation and a measuring machine having equivalent functions can be used. As the contour shape measuring machine, for example, CONTOURECORD 1700SD3 manufactured by Tokyo Seimitsu Co., Ltd. or a measuring machine having an equivalent function can be used.

Since the bottom portion 11 and the side portion 12 are made of a continuous fabric, their thicknesses are close to each other. The fabric thickness T (shown in FIG. 3) is, for example, in the range 0.1 mm to 1 mm. The thickness of the bottom portion 11 is, for example, within the range of 0.1 mm to 1 mm. The thickness of the side surface portion 12 is, for example, within the range of 0.1 mm to 1.5 mm. The thickness of bottom surface portion 11 and the thickness of side surface portion 12 may be different from each other. The thickness T of the fabric is preferably in the range 0.15 mm to 0.5 mm. When the thickness T of the fabric is within this range, there is an advantage that the tray made of the fabric has sufficient mechanical strength and the fabric can be easily stretched during the drawing process. If the thickness T of the fabric is too small, wrinkles tend to form around the curved surface, which is not preferable.

The dimensions of each portion of the tray 10 are not particularly limited. 2 and 3 show L 1 , L ₂ , W ₁ , _{W 2 and} H as examples of the dimensions of the parts of the tray 10 . In FIG. 2, L ₁ represents the length of the bottom portion 11 in the long side direction. Reference character L ₂ represents the length from the upper end of the side wall 12b to the upper end of the side wall 12d that are opposed to each other. Reference W ₁ represents the length of the bottom surface portion 11 in the short side direction. Reference character _W2 represents the length from the upper end of the side wall 12a to the upper end of the side wall 12c facing each other. In FIG. 3 , the depth H of the tray 10 is represented by the height distance from the surface of the bottom portion 11 to the upper end of the side portion 12 .

The texture of the woven fabric that the fabric comprises can be, for example, a plain weave or a twill weave. Preferably, the woven fabric is a high heat resistant fiber. The woven fabric can be, for example, at least one selected from the group consisting of glass fibers, alumina fibers and silica fibers. Among these, it is preferable to use glass fiber as the woven fabric from the viewpoint of food sanitation, the viewpoint of balance between hardness and strength, and the viewpoint of low cost.

The specifications of the glass fiber are not particularly limited, but may be, for example, the specifications shown below. The weight per unit area of the woven fabric is, for example, in the range of 75 g/m ² to 800 g/m ² . The yarn density of the woven fabric is, for example, in the range of 10 threads/25 mm to 65 threads/25 mm. The yarn density in the warp direction of the woven fabric may be different from the yarn density in the weft direction. The thickness of the woven fabric is, for example, in the range of 0.07 mm to 0.7 mm. The TEX count of one thread is, for example, in the range of 22 g/1000 m to 540 g/1000 m.

The fluororesin layer is formed on both sides of the woven fabric. The fluororesin layer contains at least one selected from the group consisting of polytetrafluoroethylene (PTFE), perfluoroalkoxyalkane (PFA), and perfluoroethylene propene copolymer (FEP). The fluororesin layer preferably contains PTFE from the viewpoint of heat resistance, chemical resistance and mechanical strength. The fluororesin layer can include a first fluororesin layer and a second fluororesin layer. The first fluororesin layer can be omitted.

The first fluororesin layer is formed, for example, on both sides of the woven fabric. The first fluororesin layer formed on the woven fabric can exist in the gaps between the warp and weft threads forming the woven fabric and on the surfaces of these threads. Since the first fluororesin layer exists between the woven fabric and the second fluororesin layer, the adhesiveness between the woven fabric and the first fluororesin layer and the first fluororesin layer and the second fluororesin layer are improved. Adhesion to the layer can be enhanced. Therefore, if the fluororesin layer includes the first fluororesin layer and the second fluororesin layer, cracks in the manufactured tray can be reduced. The first fluororesin layer may be colored by containing an inorganic pigment, carbon black, or the like.

The thickness of the first fluororesin layer is, for example, within the range of 2 μm to 30 μm, preferably within the range of 10 μm to 25 μm. If the thickness of the first fluororesin layer is too small, the adhesiveness between the woven fabric and the second fluororesin layer cannot be sufficiently enhanced, and when the fabric is subjected to drawing, cracks and delamination between layers may occur. may become more likely to occur. If the thickness of the first fluororesin layer is excessively large, when the tray is used for cooking, the residual stress generated by the drawing process is released and the tray tends to be easily deformed.

The surface shape of the first fluororesin layer laminated on the woven fabric is affected by the shape of the woven fabric. The thickness of the first fluororesin layer is preferably such that the unevenness of the surface caused by the shape of the woven fabric is flattened. The thickness of the first fluororesin layer that satisfies this requirement is, for example, about 10 μm to 25 μm. It is preferable that the surface of the first fluororesin layer is nearly flat, because the adhesion between the first fluororesin layer and the second fluororesin layer is excellent.

The first fluororesin layer contains, for example, at least one selected from the group consisting of polytetrafluoroethylene (PTFE), perfluoroalkoxyalkane (PFA), and perfluoroethylene propene copolymer (FEP). Preferably, the first fluororesin layer mainly contains PTFE. The first fluororesin layer may contain only one kind of fluororesin, or may contain two or more kinds of fluororesins. By including PTFE as the fluororesin in the first fluororesin layer, the first fluororesin layer having excellent heat resistance, chemical resistance and mechanical strength can be obtained. The first fluororesin layer may contain a colorant as described above. As the colorant, for example, at least one selected from the group consisting of inorganic pigments and carbon black can be used.

The first fluororesin layer can be formed on the woven fabric by impregnation coating, for example. Details of the impregnation coating will be described later.

The second fluororesin layer is formed on the first fluororesin layer. The second fluororesin layer is formed, for example, on both sides of the first fluororesin layer formed on both sides of the woven fabric. The second fluororesin layer is, for example, a film made of fluororesin. The second fluororesin layer has higher permeation resistance than the first fluororesin layer. The water vapor transmission rate of the fabric including the second fluororesin layer is, for example, 25 g/m ² ·day·mm or less. The second fluororesin layer can be made of a film produced by any one of the following three production methods. That is, the second fluororesin layer can be a film obtained by extruding a pellet in a heated and melted state into a flat shape, or a film obtained by compression molding a powder into a cylindrical shape and then cutting it into thin pieces. Alternatively, the second fluororesin layer can be formed by applying a liquid dispersion of powder to the woven fabric or the first fluororesin layer, firing the coated layer, and then applying an external compressive force to the fired film. It may also be a film with improved permeation resistance by reducing microscopic voids between resin molecules. The second fluororesin layer may or may not be light transmissive. When the second fluororesin layer is light transmissive, the user of the tray can recognize the color of the first fluororesin layer when the first fluororesin layer is colored.

The thickness of the second fluororesin layer is, for example, within the range of 8 μm to 150 μm, preferably within the range of 15 μm to 80 μm. If the thickness of the second fluororesin layer is excessively small, when the tray 10 is manufactured by drawing, cracks are likely to occur at a portion bent with a small radius of curvature, or even if cracks do not occur, a single layer on the inner surface of the tray may occur. It is not preferable because it may become impossible to achieve sufficient permeation resistance as a membrane structure. If the thickness of the second fluororesin is excessively large, when the tray is used for cooking, the residual stress generated by the drawing process is released and the tray tends to be easily deformed.

The second fluororesin layer contains, for example, at least one selected from the group consisting of polytetrafluoroethylene (PTFE), perfluoroalkoxyalkane (PFA), and perfluoroethylene propene copolymer (FEP). Preferably, the second fluororesin layer mainly contains PTFE. The second fluororesin layer may contain only one kind of fluororesin, or may contain two or more kinds of fluororesins. Since the second fluororesin layer mainly contains PTFE as the fluororesin, it is possible to obtain the second fluororesin layer excellent in heat resistance, chemical resistance and mechanical strength. When the second fluororesin layer contains PTFE, the ratio of the weight of PTFE to the weight of the second fluororesin layer is, for example, in the range of 70% to 100%, preferably in the range of 95% to 100%. It is in.

Next, an example of a tray manufacturing method according to an embodiment will be described with reference to the drawings. Here, a case where the fluororesin layer includes a first fluororesin layer and a second fluororesin layer will be described.

<Fabric manufacturing>
First, a laminate is formed by forming a first fluororesin layer on a woven fabric. FIG. 6 is a cross-sectional view schematically showing an example of an apparatus and production line for impregnating and coating a glass cloth as a woven fabric with PTFE.

Reference numeral 30 in the figure denotes a delivery roll that delivers glass cloth 31 as a base material. An impregnation bath 33 filled with an aqueous dispersion 32 of PTFE resin particles is arranged downstream of the delivery roll 30 . The glass cloth 31 wound around the delivery roll 30 is fed through the roll 34a to the side of the roll 34b arranged in the aqueous dispersion 32 of the impregnation tank 33, and the aqueous dispersion 32 is applied to the glass cloth 31. A pair of doctor rolls 35 are arranged above the impregnation tank 33 to scrape off excess aqueous dispersion 32 . Above the doctor roll 35, the heating furnaces 7 are arranged so that the heat treatment temperatures are different from each other. The heating furnace 7 is divided into three blocks, a drying section 7a, a heating section 7b, and a baking section 7c, in order from the bottom. is controlled as Downstream of the heating furnace 7, rolls 34c, 34d and 34e and a winding roll 9 are arranged.

Using the apparatus having the above configuration, the first fluororesin layer is formed on the woven fabric by the following procedure.

First, the glass cloth 31 wound around the delivery roll 30 is sent to the roll 34b side arranged in the PTFE resin particle aqueous dispersion 32 of the impregnation tank 33, and the aqueous dispersion 32 is applied to the glass cloth 31. Next, excess aqueous dispersion 32 applied to the surface of glass cloth 31 is scraped off by a pair of doctor rolls 35 . Subsequently, the glass cloth 31 coated with the PTFE resin is sent to the drying section 7a of the heating furnace 7, and the coated PTFE resin is dried at a temperature of 100° C. or less to evaporate the moisture in the aqueous dispersion 32. Next, the glass cloth 31 is sent to the heat treatment section 7b and slowly heat-treated at, for example, 305° C. to remove the surfactant, additive, binder, etc. in the aqueous dispersion 32 .

In the subsequent firing section 7c, firing may or may not be performed. When firing is performed in the firing section 7c, the firing temperature is set to a temperature equal to or higher than the melting point of the PTFE resin. The laminate 8 that has passed through the baking section 7c is wound up on a winding roll 9 via rolls 34c, 34d and 34e. Thus, a laminate is obtained in which the first fluororesin layer is formed on the woven fabric.

Here, "drying" is preferably a step of evaporating water in the coated PTFE resin aqueous dispersion at a temperature of 100° C. or less. In addition, the "heat treatment" is a step of treating and removing components other than the PTFE resin, such as surfactants, additives, and binders, in the applied aqueous dispersion of PTFE resin particles within a predetermined temperature range. is preferred. The temperature range of the heat treatment is preferably 305°C or higher and lower than 340°C.

Next, a second fluororesin layer is laminated on the first fluororesin layer included in the obtained laminate. When the first fluororesin layer is omitted, the second fluororesin layer may be laminated on the woven fabric. However, if a fabric consisting of only the woven fabric and the first fluororesin layer is subjected to drawing, which will be described later, the fabric tends to tear, which is not preferable.

As an example of the method of laminating the second fluororesin layer, there is a method of thermally laminating a PTFE film on the first fluororesin layer. That is, here, a PTFE film is used as the second fluororesin layer. A PTFE film can be obtained, for example, by compression-molding a fluororesin molding powder obtained by suspension polymerization into a cylindrical shape at 50 MPa, firing at 350 to 420° C., and cutting. As the second fluororesin layer, not only a PTFE film but also a PFA film or an FEP film can be used.

Thermal lamination can be performed, for example, by the following method.

First, the laminate and PTFE film produced above are cut into desired dimensions. They are then laminated together using a roll laminator. This bonding is performed under the conditions that the roll temperature is in the range of 360° C. to 420° C., the linear pressure is in the range of 20 N/cm to 60 N/cm, and the roll speed is in the range of 1 m/min to 4 m/min. . By performing lamination under such conditions, the first fluororesin layer and the second fluororesin layer are sufficiently adhered over the entire surface, so that separation due to subsequent heating during tray manufacture can be suppressed.

The roll temperature is, for example, 360° C. to 420° C., preferably 380° C. to 400° C., as described above. If the roll temperature is lower than 360°C, there is a possibility of causing poor fusion, and if it exceeds 420°C, PTFE decomposes, which is not preferable.

The linear pressure is, for example, 20 N/cm to 60 N/cm, preferably 30 N/cm to 40 N/cm, as described above. If the linear pressure is lower than 20 N/cm, there is a possibility that defective fusion may occur.

The roll speed is, for example, 0.5 m/min to 4 m/min, as described above. If the roll speed is lower than 0.5 m/min, the production efficiency will be poor, and if it is higher than 4 m/min, there is a possibility that defective fusion may occur.

<Tray manufacturing>
An example of a method of manufacturing the tray shown in FIG. 1 using the fabric produced by the method described above will now be described with reference to FIGS. A tray is processed into a three-dimensional shape by subjecting one sheet of fabric to a drawing process. The tray therefore consists of a single-layer fabric. 7 to 10 show cross-sectional views of fabrics, molds, etc. for each step of the tray manufacturing method.

First, the fabric 100 is placed on the concave mold 20 as shown in FIG. Although the shape of the fabric 100 is not particularly limited, for example, a square, rectangular or circular fabric is used. The concave mold 20 has a concave portion 200 and a flat portion 201 . The shape and dimensions of the concave portion 200 of the concave mold 20 are preferably changed according to the desired shape of the tray. The shape of the concave portion 200 of the concave mold 20 is, for example, a cube, a rectangular parallelepiped, or a cylindrical shape.

Next, as shown in FIG. 8, the flat portion 201 of the concave mold 20 and the outer peripheral portion of the fabric 100 are fixed. This fixing is performed using fixing jigs 22a and 22b. If the fixing by the jig is loose, there is a possibility that the fabric 100 will come off from the jig in the squeezing process, which will be described later. Therefore, it is preferable to strongly fix the fabric 100 to the flat portion 201 of the concave mold 20 .

Subsequently, as shown in FIG. 9, a convex mold 21 having convex portions 210 is prepared. The shape of the convex portion 210 of the convex mold 21 is preferably the same as the shape of the concave portion 200 of the concave mold 20 . Moreover, it is preferable that the dimension of the convex portion 210 of the convex mold 21 is smaller than the dimension of the concave portion 200 of the concave mold 20 . The radius of curvature of the edge 211 of the projection 210 is preferably the same as the first radius of curvature of the intended tray. That is, by appropriately changing the radius of curvature of the edge portion 211 of the convex portion 210, the first radius of curvature of the manufactured tray can be controlled.

Next, the convex mold 21 is heated to 260.degree. C. to 390.degree. The temperature of the convex mold 21 can be appropriately changed according to the melting point of the fluororesin forming the fabric 100, the thickness of the fabric 100, and the like. After that, as a drawing step, while maintaining the temperature of the convex mold 21, the convex mold 21 is moved to the fabric 100 so that the convex part 210 enters the concave part 200 of the concave mold 20 through the fabric 100. Press down gradually. By doing so, the fabric 100 is gradually stretched along the shape of the convex portion 210 . By gradually stretching the fabric 100, cracks and wrinkles in the manufactured tray 10 can be suppressed. Less cracks and creases in the manufactured tray are preferable because food can be prevented from entering cracks and creases.

As shown in FIG. 10, when the entire surface of the convex portion 210 of the convex mold 21 comes into contact with the concave portion 200 of the concave mold 20 via the fabric 100, the heating of the convex mold 21 is stopped. In this state, when the convex mold 21, the concave mold 20 and the fabric 100 are cooled to room temperature, the shape of the stretched fabric 100 is fixed and the tray 10 shown in FIG. 1 is obtained.

The tray according to the embodiment is suitably used for cooking with heat in an oven. Since the tray according to the embodiment has excellent heat resistance, the tray is not easily deformed even if the food is repeatedly cooked at a temperature within the range of 200° C. to 280° C., for example. The tray can be used as a cooking tray or cooking sheet. The tray according to the embodiment can also be placed on a metal tray and used for cooking. Alternatively, when cooking using far-infrared rays as a heat source, the tray according to the embodiment can be used as a simple pan instead of a metal pan. The tray according to the embodiment is excellent in heat resistance and releasability, and has no seams, so that food can be prevented from entering the seams.

[Example]
Examples are described below, but embodiments are not limited to the examples described below.

(Example 1)
A glass cloth was prepared as the woven fabric. This glass cloth has a mass per unit area of 195 g/m ² , a thread density in the longitudinal direction of 40 threads/25 mm, a thread density in the transverse direction of 30 threads/25 mm, and TEX counts of the warp and weft threads. were both 68 g/1000 m.

A glass cloth was cut into a predetermined size, and the impregnation coating described with reference to FIG. 6 was repeated multiple times. An aqueous dispersion in which PTFE resin particles and carbon black were dispersed was used as the coating liquid. The solid content concentration of the PTFE resin in this aqueous dispersion was 58 wt %. By repeating the impregnation coating, a laminate was obtained in which the first fluororesin layer was formed on the glass cloth. This laminate had the first fluororesin layers on both sides of the glass cloth, and the thickness of the laminate was about 240 μm.

Next, a PTFE film (manufactured by Chukoh Kasei Kogyo Co., Ltd.) having a thickness of about 25 μm is laminated on both sides of the first fluororesin layer, and the roll temperature is 400 ° C., the linear pressure is 30 N / cm, and the roll speed is 0.5 m / min. Thermal lamination was performed under the conditions of As a result, a fabric was obtained in which the second fluororesin layers were formed on both sides of the first fluororesin layer. This fabric was colored black because the first fluororesin layer contained carbon black as a coloring agent.

The resulting fabric was drawn by the method described with reference to FIGS. 7-10 to produce trays having the shapes shown in FIGS. 1-3. However, the flange portion of the manufactured tray had the downward protrusion described in FIG. 4 over its entire circumference. This tray was made of a single-layered fabric having a bottom portion and side portions extending in the height direction from the bottom portion. The tray further included a flange portion extending from the upper edge of the side portion.

The dimensions of each portion of the manufactured tray will be described with reference to FIGS. 2 and 3. FIG. The length L ₁ of the bottom portion in the long side direction was 255 mm. The length L ₂ from the upper end of the short side wall facing each other to the upper end of the other short side wall was 261 mm. The length W ₁ of the bottom portion in the short side direction was 217 mm. The length _W2 from the upper end of the long side wall facing each other to the upper end of the other long side wall was 223 mm. The thickness T of the fabric was 0.29 mm. The depth H of the tray was 10 mm.

Using a contour measuring machine (CONTOURECORD 1700SD3 manufactured by Tokyo Seimitsu Co., Ltd.), the first radius of curvature defined by the inner surface of the bottom surface and the inner surface of the side surface was measured to be 2.5 mm. Also, a CNC image measuring machine (NEXIV VMZ-R4540 manufactured by Nikon Corporation) was used to measure the second radius of curvature defined by the inner surfaces of two adjacent side walls. The second radius of curvature near the outer edge 110 of the bottom portion 11 was 7.2 mm. In the vicinity of the upper end 121 of the side surface portion 12, the radius of curvature defined by the inner surfaces of the two adjacent side walls was 8.1 mm.

The tray according to Example 1 was free of seams and cracks (rips). Food was placed on this tray and cooked at a set temperature of 280° C. for 60 minutes using a cooking oven. Even after cooking at a high temperature of 280° C., the releasability of the food from the tray was good, and the tray was hardly deformed. That is, the tray according to Example 1 was excellent in heat resistance and releasability, and had no seams.

(Example 2)
As described below, Example 2 was fabricated in the same manner as Example 1, except that the dimensions of each portion of the tray (see also FIG. 2) were varied and the formation of the downward protrusion was omitted. A tray was produced.

In the tray according to Example 2, the length L ₁ of the bottom portion in the long side direction was 265 mm. The length L ₂ from the upper end of the short side wall facing each other to the upper end of the other short side wall was 269 mm. The length W ₁ of the bottom surface in the short side direction was 227 mm. The length _W2 from the upper end of the long side wall facing each other to the upper end of the other long side wall was 231 mm. The thickness T of the fabric was 0.29 mm. The depth H of the tray was 10 mm.

Using a contour measuring machine (CONTOURECORD 1700SD3 manufactured by Tokyo Seimitsu Co., Ltd.), the first curvature radius defined by the inner surface of the bottom surface and the inner surface of the side surface was measured to be 3.5 mm. . Also, a CNC image measuring machine (NEXIV VMZ-R4540 manufactured by Nikon Corporation) was used to measure the second radius of curvature defined by the inner surfaces of two adjacent side walls. The second radius of curvature near the outer edge 110 of the bottom surface portion 11 was 9.5 mm. In addition, in the vicinity of the upper end 121 of the side portion 12, the radius of curvature defined by the inner surfaces of the two adjacent side walls was 12.5 mm.

The tray according to Example 2 had no seams or cracks. Food was placed on this tray and cooked at a set temperature of 280° C. for 60 minutes using a cooking oven. Even after cooking at a high temperature of 280° C., the releasability of the food from the tray was good, and the tray was hardly deformed. That is, the tray according to Example 2 was excellent in heat resistance and releasability, and had no seams.

(Example 3)
A tray according to Example 3 was produced in the same manner as in Example 1, except that the second fluororesin layer was omitted.

The tray according to Example 3 did not have a seam, but a minute tear occurred in a part of the edge portion of the inner surface of the tray stretched by the drawing process. However, even when the food was placed on this tray and cooked using a cooking oven at a set temperature of 280° C. for 60 minutes, the tray was hardly deformed. In addition, the releasability of the food from the tray was good even after cooking. That is, the tray according to Example 3 was excellent in heat resistance and releasability, and had no seams.

(Comparative example 1)
First, in the same manner as in Example 1, a fabric was obtained in which the second fluororesin layers were formed on both sides of the first fluororesin layer. By folding this fabric and heat-treating it, a tray having a rectangular parallelepiped shape with an open top including a portion where the fabric was double-layered was produced.

Using a contour measuring machine (CONTOURECORD 1700SD3 manufactured by Tokyo Seimitsu Co., Ltd.), the first curvature radius defined by the inner surface of the bottom surface and the inner surface of the side surface was measured to be 2.0 mm. . Also, a CNC image measuring machine (NEXIV VMZ-R4540 manufactured by Nikon Corporation) was used to measure the second radius of curvature defined by the inner surfaces of two adjacent side walls. The second radius of curvature near the outer edge 110 of the bottom surface portion 11 was 0.1 mm. In the vicinity of the upper end 121 of the side portion 12, the radius of curvature defined by the inner surfaces of the two adjacent side walls was 1.0 mm.

Food was placed on the tray according to Comparative Example 1 and cooked at a set temperature of 280° C. for 60 minutes using a cooking oven. Even after cooking at a high temperature of 280° C., the releasability of the food from the tray was good, and the tray was hardly deformed. However, the tray according to Comparative Example 1 had a portion where the fabric was laminated. In other words, the tray according to Comparative Example 1 did not have a single layer structure, but had seams. When food is placed on such a tray and repeatedly heated and cooked, there is a high possibility that the food will get into the seams and/or corners, for example. And if food gets into the seams and/or corners, it is considered difficult to clean, which is undesirable.

(Comparative example 2)
The same method as in Comparative Example 1, except that the first radius of curvature is 0.5 mm, and the radius of curvature defined by the inner surfaces of two adjacent side walls near the upper end 121 of the side surface portion 12 is 1.0 mm. A tray according to Comparative Example 2 was produced.

Food was placed on the tray according to Comparative Example 2 and cooked at a set temperature of 280° C. for 60 minutes using a cooking oven. Even after cooking at a high temperature of 280° C., the releasability of the food from the tray was good, and the tray was hardly deformed. However, the tray according to Comparative Example 2 had a portion where the fabric was laminated. In other words, the tray according to Comparative Example 2 did not have a single layer structure, but had seams. When food is placed on such a tray and repeatedly heated and cooked, there is a high possibility that the food will get into the seams and/or corners, for example. And if food gets into the seams and/or corners, it is considered difficult to clean, which is undesirable.

As described above, both the trays produced in Examples 1 and 2 and the tray produced in Example 3 could be used as practical trays. However, the trays made in Examples 1 and 2 were superior to the tray made in Example 3 in that no tears occurred. That is, the fluororesin layer preferably includes not only the first fluororesin layers formed on both sides of the woven fabric but also the second fluororesin layers formed on the first fluororesin layers on both sides of the tray. .

It should be noted that the present invention is not limited to the above-described embodiments, and various modifications can be made in the implementation stage without departing from the scope of the invention. Further, each embodiment may be implemented in combination as appropriate, in which case the combined effect can be obtained. Furthermore, various inventions are included in the above embodiments, and various inventions can be extracted by combinations selected from a plurality of disclosed constituent elements. For example, even if some constituent elements are deleted from all the constituent elements shown in the embodiments, if the problem can be solved and effects can be obtained, the configuration with the constituent elements deleted can be extracted as an invention.
Hereinafter, the invention described in the scope of claims at the time of filing of the present application will be additionally described.
[1] A tray comprising a bottom portion and side portions extending in a height direction from the bottom portion,
The bottom part and the side part are made of a fabric with a single-layer structure,
The fabric includes a woven fabric and a fluororesin layer formed on both sides of the woven fabric.
[2] The tray according to [1], wherein the fabric has a water vapor transmission rate of 25 g/m ² ·day·mm or less.
[3] The tray according to [1] or [2], wherein a first radius of curvature defined by the inner surface of the bottom portion and the inner surface of the side portion is 1.5 mm or more.
[4] the outer edge of the bottom portion is a polygon having three or more corners;
The side portion has a plurality of side walls corresponding to the number of the three or more corners,
Regarding the two adjacent side walls, the second radius of curvature defined by the inner surface of one side wall and the other side wall is 5 mm or more. tray.
[5] The fluororesin layer includes a first fluororesin layer formed on the woven fabric and a second fluororesin layer formed on the first fluororesin layer,
The first fluororesin layer contains at least one selected from the group consisting of polytetrafluoroethylene (PTFE), perfluoroalkoxyalkane (PFA), and perfluoroethylene propene copolymer (FEP) [1]- The tray according to any one of [4].
[6] The second fluororesin layer contains at least one selected from the group consisting of polytetrafluoroethylene (PTFE), perfluoroalkoxyalkane (PFA), and perfluoroethylene propene copolymer (FEP) [ 5].
[7] The tray according to any one of [1] to [6], wherein the woven fabric is at least one selected from the group consisting of glass fiber, alumina fiber and silica fiber.
[8] The tray according to any one of [1] to [7], wherein the fabric has a thickness of 0.1 mm to 1 mm.
[9] The tray according to any one of [1] to [8], wherein the fabric does not have a portion where two or more layers overlap.
[10] The tray according to any one of [1] to [9], which is used for cooking with heat in an oven.

DESCRIPTION OF SYMBOLS 3... Woven fabric 4... 1st fluororesin layer 5... 2nd fluororesin layer 6... fluororesin layer 7... Heating furnace 8... Laminated body 9... Winding roll 10... Tray 11... Bottom Part 12a to 12d Side wall 13 Flange 14 Inner surface 15 Outer surface 20 Concave mold 21 Convex mold 22a to 22b Fixing jig 30 Delivery roll 31 Glass cloth 32 Aqueous dispersion 33 Impregnation tank 34 Roll 35 Doctor roll 100 Fabric 110 Outer edge of bottom surface 121 Upper end of side surface 131 Lower protrusion 200 Concave portion 201 Flat portion 210 Convex portion 211 Edge portion R1 First radius of curvature R2 Second radius of curvature.

Claims (8)

A tray comprising a bottom portion and side portions extending in a height direction from the bottom portion,
The bottom part and the side part are made of a fabric with a single-layer structure,
The fabric includes a woven fabric and fluororesin layers formed on both sides of the woven fabric,
A first curvature radius defined by the inner surface of the bottom portion and the inner surface of the side portion is 1.5 mm or more,
The outer edge of the bottom portion is a polygon having three or more corners,
The side portion has a plurality of side walls corresponding to the number of the three or more corners,
A second radius of curvature defined by the inner surface of one side wall and the other side wall of two adjacent side walls is 5 mm or more. 2. The tray according to claim 1, wherein said fabric has a water vapor transmission rate of 25 g/m ^<2> *day*mm or less. The fluororesin layer includes a first fluororesin layer formed on the woven fabric and a second fluororesin layer formed on the first fluororesin layer,
1 or 2, wherein the first fluororesin layer contains at least one selected from the group consisting of polytetrafluoroethylene (PTFE), perfluoroalkoxyalkane (PFA), and perfluoroethylene propene copolymer (FEP) 2. The tray according to 2 . 4. The second fluororesin layer contains at least one selected from the group consisting of polytetrafluoroethylene (PTFE), perfluoroalkoxyalkane (PFA), and perfluoroethylene propene copolymer (FEP). Tray as described. The tray according to any one of claims 1 to 4, wherein said woven fabric is at least one selected from the group consisting of glass fiber, alumina fiber and silica fiber. A tray according to any preceding claim , wherein the fabric has a thickness of 0.1 mm to 1 mm. A tray according to any one of claims 1 to 6, wherein the fabric does not have two or more overlapping portions. The tray according to any one of claims 1 to 7, which is used for cooking with heat in an oven.

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