TW201722726A - Absorbent sheet - Google Patents

Abstract

Provided is an absorbent sheet for microwave ovens, which is free from ply separation even if heated in a microwave oven. A film layer (10) of this absorbent sheet (1) comprises: a surface layer (11) that is formed from a polyester; an inner layer (12) that is positioned below the surface layer (11) and is formed from a polyester; and a plurality of open pores (14) that penetrate through the surface layer (11) and the inner layer (12). The inner layer (12) is formed from a polyester that is modified with a bi- or higher functional compound having an epoxy group; and the film layer (10) and a fiber layer (13) are at least partially bonded with each other.

Description

Absorbent sheet

The present invention relates to an absorbent sheet for a microwave oven that can absorb juice escaping from food.

Absorbent sheets for absorbing juice which are exuded from slices of fish, beef, etc. which are placed on a tray made of expanded polystyrene or the like are known. For example, Patent Document 1 discloses a food packaging material for a microwave oven, comprising: a first layer formed by a hydrophobic fiber sheet in contact with a food, a second layer formed of a water-absorbent sheet to form water, and a second layer The laminated sheet of the outermost layer formed of the thermoplastic synthetic resin film of the hole is perforated with a squeezing roller and a cooling roll, and the vent hole is passed through the outermost thermoplastic synthetic resin film.

[Advanced technical literature] [Patent Literature]

[Patent Document 1] Japanese Patent No. 4060261

Patent Document 1 discloses that a layer of a hydrophobic fiber sheet, a water-absorbent sheet, and a thermoplastic synthetic resin film is adhered to by a layer formed by heat or a partially melted resin or the like. . However, if a laminated sheet formed of different materials is heated in a microwave oven, interlayer peeling may occur.

The present invention provides an absorbent sheet which does not cause interlayer peeling even when heated in a microwave oven.

The present invention relates to an absorbent sheet for a microwave oven comprising a film layer on which a food is placed and a fiber layer capable of absorbing juice flowing from the food.

The absorbent sheet according to the present invention is characterized in that the film layer has a surface layer made of polyester, an inner layer made of polyester between the surface layer and the fiber layer, and the inner surface layer and the inner layer. A plurality of openings of the layer, wherein the inner layer is formed of a polyester modified with a compound having two or more functional groups, and the film layer and the fiber layer are bonded to each other at least in part.

The film layer has a flat portion and a plurality of concave portions located between the flat portions, and the plurality of openings are located in the flat portion, so that the juice oozing from the food can be gradually passed from the flat portion directly contacting the food through the opening. Move toward the fiber layer to absorb it.

The plurality of openings are further located in the recess, Therefore, the juice flowing into the concave portion can be quickly moved to the fibrous layer for absorption.

The film layer and the fiber layer are joined to each other only in the concave portion. In the flat portion, since the film layer and the fiber layer are separated from each other, a temporary storage of juice can be formed between the film layer and the fiber layer in the flat portion. Space.

Since the ratio of the area of the flat portion to the surface area of the film layer is in the range of 30 to 70%, it is possible to suppress the occurrence of liquid return (rewetting) from the opening located in the flat portion.

Further, the first direction and the second direction intersecting therewith, the diameter of the opening is 0.5 mm to 3.0 mm, and the plurality of openings are disposed apart from each other in the first direction and the second direction, and the first direction In addition, since the separation size in the second direction is 3.0 mm to 20.0 mm, the contact surface of the food is not dried, and the excess oil content from the food can be gradually absorbed, and good rewetting can be exhibited.

Since the concave portion is a concave groove that extends linearly, the juice that has accumulated in the concave portion can be quickly moved to the fiber layer through the opening, and the juice layer can be prevented from being absorbed into the thin film along the concave groove. The outside.

Since the fiber layer contains at least one type of fiber selected from the group consisting of pulp fibers, rayon fibers, polyester fibers, and sheath-sheath thermoplastic fibers having a sheath melting point of 200 ° C or higher, the desired amount can be absorbed. Keep the liquid and keep it, even if it is heated in a microwave oven, it won't Loss of liquid absorption.

Since the thickness dimension in the flat portion of the fiber layer is larger than the thickness dimension in the concave portion of the fiber layer, the juice absorbed by the fiber layer from the opening of the flat portion can be absorbed in a relatively large amount and held.

Since the fiber density in the concave portion of the fiber layer is higher than the fiber density in the flat portion of the fiber layer, the juice flowing into the concave portion can be quickly absorbed.

Since the film layer has a high melting point portion and a low melting point portion in the flat portion, the low melting point portion exhibits sealing properties even at a relatively low temperature, and the film layer and the fiber layer can be stably joined.

In the absorbent sheet of the present invention, since the inner layer of the film layer is formed of a polyester modified with a compound having a bifunctional or higher epoxy group, the surface layer and the fiber layer are strongly bonded to each other via the inner layer. Therefore, even if it is heated by a microwave oven, there is no concern that interlayer peeling occurs between the film layer and the fiber layer.

1‧‧‧Absorbable flakes

10‧‧‧film layer

11‧‧‧ surface layer

12‧‧‧ inner layer

13‧‧‧Fiber layer

14‧‧‧Opening

15‧‧‧ Flat Department

16‧‧‧ recess

X‧‧‧1st direction

Y‧‧‧2nd direction

The drawings show aspects of a particular embodiment of the invention, and are not only indispensable for the invention, but also include alternative and desirable embodiments.

Fig. 1 is a perspective view of an absorbent sheet of the present invention.

FIG. 2 is a cross-sectional view taken along line II-II of FIG. 1. FIG.

3 is a graph showing measurement results of a thermal state of a sample cut out from a flat portion in a film layer by differential scanning calorimetry (Differential Scanning Calorimetry).

[Formation for carrying out the invention]

The following embodiments relate to the absorbent sheet shown in the attached drawing, and are not only indispensable for the invention, but also include a selective and desirable structure. Hereinafter, the absorbent sheet of the present invention will be described with reference to the attached drawings.

As shown in FIG. 1 and FIG. 2, the absorbent sheet 1 includes a first direction X, a second direction Y intersecting therewith, a thickness direction Z, a film layer 10 on which food is placed, and a juice absorbing from the food. Fiber layer 13. The film layer (porous PET film) 10 has a surface layer 11 made of polyester, an inner layer 12 made of polyester disposed on the lower side of the surface layer 11 and disposed between the surface layer 11 and the fiber layer 13. The film layer 10 has a desired heat resistance as described later, and also has a function of gradually moving the juice oozing out from the food to the fiber layer 13, and also functions as a juice transition layer. Further, the film layer 10 is a so-called hydrophobic layer, the inner layer is a so-called low temperature sealing layer, and the fiber layer 13 is a so-called hydrophilic layer.

The absorbent sheet 1 has a flat portion 15 which is separated from each other in the first direction X and extends in the second direction Y, and a plurality of concave groove-like recesses 16 (sealing lines) which are positioned between the flat portions 15. Forming a film The surface layer 11 and the inner layer 12 of the layer 10 are joined to each other by bonding or fusion, and the film layer 10 and the fiber layer 13 are thermally fused to each other in the concave portion 16. The absorbent sheet 1 has a cross-sectional shape in which the flat portion 15 and the concave portion 16 alternately overlap each other in the first direction X.

In the film layer 10 and the fiber layer 13, since the surface of the film layer 10 is smooth, the bonding by the adhesive is low, but the bonding strength is low, and even when the bonding between the materials is low, the affinity between the materials is low. The required joint strength cannot be achieved. In the present embodiment, since the inner layer 12 of the thin film layer 10 is a polyester modified with a compound having a bifunctional or higher epoxy group, the surface layer 11 made of polyester has a high water absorbing polarity. The affinity of any layer of the fiber layer 13 also becomes high. Therefore, in the recessed portion 16, the surface layer 11 sandwiching the inner layer 12 and the three layers of the fiber layer 13 are firmly joined to each other by thermal bonding.

Further, since the polyester resin has a high melting point, the surface layer 11 and the inner layer 12 are not melted after being heated by a microwave oven for food conditioning. Therefore, even after the absorbent sheet 1 is heated by using a microwave oven, there is no case where the inner layer 12 is melted and peeled off from the fiber layer 13. Therefore, there is no concern that interlayer peeling occurs between the film layer 10 and the fiber layer 13 after heating in a microwave oven.

The surface layer 11 can be formed using a film formed of a well-known polyester resin formed of a polycondensate of a dicarboxylic acid and a diol. Although polyethylene terephthalate (PET) and polybutylene terephthalate (PBT) are exemplified as the polyester resin which can be used in the present invention, it is not limited thereto.

The inner layer 12 can be used to have the aforementioned known polyester resin A film formed of a polyester resin modified with a bifunctional or higher epoxy compound is formed. Although it can be mentioned: ethylene glycol diepoxypropyl ether, polyethylene glycol diepoxypropyl ether, hexamethylene diglycidyl ether, bisphenol A diglycidyl ether, trimethylolpropane triglycidyl Ether, glycerol triglycidyl ether, epoxidized soybean oil, epoxidized linseed oil, heterocyclic isocyanuric acid triglycidyl ester, phenol novolac type epoxy resin, cresol novolak type epoxy resin, bis-phenylene The phenol tetraglycidyl ether is not limited to these examples, and examples of the compound having a bifunctional or higher epoxy group. The inner layer 12 may further contain at least one of a stearic acid or a lithium acetate, a sodium salt, a potassium salt, a magnesium salt, a calcium salt, a zinc salt or a manganese salt, and may also be incorporated in the molecule. More than one carboxylic acid functional polyolefin.

At least one type selected from the group consisting of pulp fibers, rayon fibers, polyester fibers, and sheath-sheath thermoplastic fibers having a sheath melting point of 200 ° C or higher can be used for the fibrous layer 13 which can absorb the juice escaping from the food. The fibers formed by the fibers are not woven. In the fiber nonwoven fabric in which the fiber layer 13 is formed, in consideration of flexibility and bulkiness, it is suitable to use a gas-laid fiber nonwoven fabric, and various known fiber nonwoven fabrics such as a spun fiber nonwoven fabric and an SMS fiber nonwoven fabric can be used.

Since the usual polyester resin used for the surface layer 11 has a melting point of about 250 ° C, it is necessary to heat treatment in order to melt and join the fiber layer 13 . When such a high-temperature treatment is performed, the high-melting-point component in the heat-fusible fiber formed of the composite fiber including the low-melting component and the high-melting component is melted by the synthetic fiber constituting the fiber layer 13, and the fiber layer is formed. 13 deterioration or hardening concerns, but by the surface layer The inner layer 12 formed of a polyester resin having a relatively low melting point is disposed between the fiber layer 13 and the inner layer 12, and the inner layer 12 functions as a low-temperature sealing layer, and the high temperature treatment of the synthetic fiber or higher is not performed. The film layer 10 and the fiber layer 13 can be joined.

In the absorbent sheet 1, the film layer 10 and the fiber layer 13 are joined to each other in the concave portion 16, whereas the film layer 10 and the fiber layer 13 are not joined to each other at the flat portion 15. Therefore, in the flat portion 15, the film layer 10 and the fiber layer 13 are not joined, and a space 18 for temporarily storing the juice oozing out from the food is formed between the inner layer 12 and the fiber layer 13. Further, even if the surface layer 11 and the inner layer 12 are thermally shrunk by heating by the microwave oven, the inner layer 12 is not thermally bonded to the flat portion 15 of the fiber layer 13, and the fiber layer 13 can be prevented from following the surface layer 11 and the inner layer 12 The case of heat shrinkage and deformation. Therefore, warpage of the absorbent sheet 1 due to heat shrinkage of the surface layer 11 and the inner layer 12 can be suppressed.

Further, referring to FIG. 1, a plurality of openings 14 penetrating the surface layer 11 and the inner layer 12 are formed in the film layer 10. The opening 14 is formed at least in the flat portion 15 at the film layer 10. Since the film layer 10 is not liquid-absorbent, the juice running out of the food cannot be directly transferred to the fiber layer 13, but a plurality of openings 14 can be formed in the flat portion 15 contacting the food. The juice gradually migrates to the fibrous layer 13. In other words, by forming a plurality of minute openings 14 in the hydrophobic film layer 10, the juice is immediately absorbed from the contact surface of the food to be in a dry state, and the oil and moisture which can be a delicious component are not absorbed. The situation, and only let the excess oil and so on slowly move to the fiber layer 13 to suck It is collected, so after heating in a microwave oven, the fried material can be maintained in a juicy state for a certain period of time (about 3 to 5 minutes).

Further, it is preferable that the opening 14 is located not only in the flat portion 15 but also in the concave portion 16. Since the juice oozing out from the contact surface of the food contacting the flat portion 15 is moved inwardly toward the concave portion 16, by forming a plurality of openings 14 in the concave portion, the juice accumulated in the concave portion 16 can be quickly moved toward the fibrous layer 13 mobile. Further, the concave portion 16 is linearly extended in the second direction Y, and the juice which is not absorbed in the fiber layer 13 can be discharged to the outside from the edge of the absorbent sheet 1 opposed to the second direction Y (discharged to the outside) Within the order). The concave portion 16 may have a curved shape or a lattice shape in addition to a straight shape, or may have a shape that intermittently extends in a certain direction.

In the present embodiment, the plurality of openings 14 are arranged in a size required to be separated from the second direction Y in the first direction X. The opening 14 is circular, and has a diameter of 0.5 mm to 3.0 mm, and is 3.0 mm to 20.0 mm in the first direction X and/or the second direction Y, and is preferably a separation size (pitch) of 5.0 mm to 10.0 mm. Is configured. In the example of the drawing, the plurality of openings 14 are arranged at equal intervals in the first direction X and the second direction Y. However, as long as the effect of the technique of the present invention can be achieved, the openings 14 may be arranged at equal intervals in the first direction X and the second direction Y. Further, the opening 14 may have various known shapes such as an elliptical shape, a rectangular shape, and a rhombic shape in addition to a circular shape.

In the method of forming the plurality of openings 14 in the film layer 10, in addition to the piercing process by the pins, well-known hot embossing (intaglio) processing can be used, for example, in the manufacture of the absorbent sheet 1, Let be a table The polyester film of the top layer 11 and the epoxy-modified polyester film which becomes the inner layer 12 can be formed by pressurizing and heating a part between a heat roll provided with a needle-like protrusion (hub) and an anvil roll. . In such hot embossing, it is preferable to set the temperature of the heat roller to be higher than the melting point of the polyester, that is, to be 200 ° C or higher. Further, when a plurality of openings 14 are formed by hot embossing, by thermally sealing the peripheral portion of the opening 14, the surface layer 11 and the inner layer 12 are only at the peripheral portion of the opening 14 without using an adhesive. They are joined to each other. Further, the juice oozing out from the surface layer 11 can be guided to the opening 14 more than the fiber density of the other portions of the film layer 10. Further, by forming the opening edge by the seal line, the sheet strength of the opening 14 is relatively high, and it is possible to suppress the shape from being collapsed and closed.

Referring to FIG. 2, in the fiber layer 13, the thickness dimension D1 in the flat portion 15 is larger than the thickness dimension D2 in the concave portion 16, specifically, the thickness dimension D1 in the flat portion 15 is 1.0 to 3.0 mm, in the recess 16 The thickness dimension D2 is 0.2 to 1.0 mm. Further, the fiber density in the concave portion 16 is higher than the fiber density of the flat portion 15 of the fiber layer 13. Specifically, the fiber density in the flat portion 15 is 0.03 to 0.1 g/cm ³ , and the fiber density of the concave portion 16 is 0.12 to 0.2 g/cm ³ . In this way, since the fiber density of the fiber layer 13 in the flat portion 15 directly contacting the food is relatively low, the contact surface is dried except that the excess oil contained in the food moving from the opening 14 is not rushed. In addition to the case, the thickness dimension D1 is relatively large and can absorb ‧ to maintain a sufficient amount of juice. Further, the fiber layer 13 is loosened by being joined to the film layer 10 in the flat portion 15, and is excellent in cushioning property. Further, since the concave portion 16 has a relatively high fiber density, the juice accumulated in the concave portion 16 can be quickly absorbed. Further, since the fiber density is relatively high in the concave portion 16, the rigidity is high, the twist of the absorbent sheet 1 can be suppressed, and the flat portion 15 is relatively soft and soft, so that the absorbent sheet 1 can be made to follow. The shape of the food is deformed. In this way, by arranging the flat portion 15 and the concave portion 16 in a well-balanced manner, the sheet strength required for the absorbent sheet 1 and the ease of deformation of the sheet can be achieved.

Moreover, the wide dimension (the dimension in the first direction X) W1 of the flat portion 15 is 2.0 to 7.0 mm, and the wide dimension (the dimension in the first direction X) W2 of the concave portion 16 is 0.5 to 3.0 mm, and the flat portion 15 is The wide size W1 becomes larger than the wide size W2 of the recess 16. As described above, since the wide size W1 of the flat portion 15 is larger than the wide size W2 of the concave portion 16, the food can be stably placed, and the juice can be slowly moved to the fibrous layer 13 at the flat portion 15.

The area ratio of the area of the flat portion 15 to the film layer 10 is preferably in the range of 30 to 70% in plan view. By setting the area ratio of the flat portion 15 within this range, the absorbent sheet 1 having good rewet properties can be obtained. That is, by adjusting the area of the flat portion 15 directly contacting the food, it is possible to suppress the liquid which is absorbed by the fiber layer 13 from flowing back from the flat portion 15. However, the film layer 10 itself does not pass through the liquid, but is returned to the liquid through the opening 14. Therefore, not only the area ratio of the flat portion 15, but also the opening area ratio of the opening 14 in the entire flat portion 15 must be predetermined. Within the scope. Specifically, the opening area of the opening 14 with respect to the surface area of the flat portion 15 (the total area ratio of the openings 14) is 10 to 30%. When such an open area ratio is 10% or less, the juice oozing from the food cannot be removed. When the fiber layer 13 is passed, the juice stays on the surface layer 11 for a relatively long period of time, and there is a concern that the food absorbs the juice. On the other hand, when the opening area ratio is 30% or more, the total area of the opening 14 is relatively large, and the contact surface of the absorption speed-increasing food is immediately dried, so that moisture which is delicious can be generated. The oil also absorbs the concerns.

In the method of forming the flat portion 15 and the concave portion 16 in the absorbent sheet 1, for example, in a state in which the film layer 10 having a plurality of openings 14 and the fiber non-woven fabric which is the fiber layer 13 are laminated, let it pass A heat roller having a plurality of ridge portions (hubs) protruding from the outer peripheral surface and an anvil roll having a flat outer peripheral surface can be formed by pressurizing and heating a portion. Further, a laminate in which the film layer 10 having the opening 14 and the fiber layer 13 are laminated is passed between a heat roller having a plurality of needle-like projections and a ridge portion and an anvil roll, and is heated by pressure. It is also possible to form a plurality of openings 14 and a plurality of recesses 16 at substantially the same time in the same process in the absorbent sheet 1.

Hereinafter, the results of evaluation of heat resistance, rewet property, and water absorption of the absorbent sheet 1 of the present invention will be described.

The evaluation of heat resistance was carried out in the next order.

(1) A sample of 10 cm × 10 cm was taken from the absorbent sheet 1.

(2) Place 1 tsp (about 5 g) of mayonnazi in the center of the surface layer 11 of the sample.

(3) Heating in a 1000 W microwave oven for 1 minute, 2 minutes, and 3 minutes.

(4) After heating, the temperature of each sample was measured with a hand-held thermometer.

(5) Remove the residual nectar from the sample and confirm the appearance of the sample.

(6) Gently wash the sample with a neutral detergent, let it dry, and use a digital camera to enter Line photography.

(7) Heating for 3 minutes If the appearance of the sample did not change, it was judged to have heat resistance.

The evaluation of the rewet property was carried out in the next order.

(1) Three sheets of 10 cm × 10 cm samples were taken from the absorbent sheet 1.

(2) Install the sample under 10 cm of the nozzle tip of the automatic burette.

(3) 1 ml of a red raw liquid colored in red was dropped on the surface layer 11 of the sample at a rate of 1.0 ml/3 seconds. The red raw food liquid was prepared by mixing 1 liter of 0.9% NaCl aqueous solution, 1.63 g of yellow No. 5, 8.5 g of red No. 102, and 2 g of red No. 2.

(4) After dropping 1 ml of the red raw liquid, it was allowed to stand for 1 minute.

(5) One piece of the filter paper having the weight (A) measured in advance and 500 g of the weight were placed in the sample.

(6) After 3 minutes, the weight was removed, and the weight (B) of the filter paper after absorbing the red raw liquid was measured.

(7) When B-A (unit g) is 0.50 g or less, it is judged that the rewet is good.

The sample of the absorbent sheet 1 of the present invention and the sample of the absorbent sheet 1 of the present invention were prepared by the above-described production method. Table 1 shows the details of the sample to be evaluated and the evaluation results.

As can be understood from Table 1, the surface layer 11 is a polyester, and the inner layer 12 is an epoxy-modified polyester of the absorbent sheets 1 of Examples 1 to 5, that is, there is no interlayer peeling and warping after heating in a microwave oven. The situation that occurs and has good rewetting properties. On the other hand, in Comparative Examples 1 and 2 in which the rubber-based hot-melt adhesive and the polyethylene film were used in the inner layer 12 instead of the epoxy-modified polyester, interlayer peeling occurred by heating by a microwave oven. Again, by the knot of Table 1 As a result, it can be confirmed that any of the air-laid pulp, the polyester non-woven fabric, and the absorbent paper can be used for the fibrous layer 13 of the absorbent sheet 1 for a microwave oven.

Further, since the absorbent sheet 1 is provided with good rewetting property and heat resistance, it is used as a cooking sheet (oil sheet) which is laid on a heat-resistant tray, for example, in order to drain the fried fried material. ) is also suitable for use. Since the absorbent sheet 1 is excellent in heat resistance, it does not crack even when it is exposed to high temperature (180 degrees), and since it has good rewetting property, the sheet contact surface of the fried material does not become too dry. It also contains a moderate amount of oil, so it can prevent rapid cooling, and the fried material can be maintained in a juicy state for a certain period of time (3 to 5 minutes).

3 shows the measurement results of the thermal state of the sample (2.0 mg) cut out from the flat portion 15 (the non-existing region of the concave portion 16) in the film layer 10 by a differential scanning calorimeter (DSC measuring device). chart. Here, the "melting point" means the peak top temperature of the endothermic peak when the DSC measuring device changes from a solid shape to a liquid state when measured at a temperature increase rate of 10 ° C /min. As the DSC measuring device, a well-known measuring device which is generally used in the field can be used. For example, a DSC-60 type DSC measuring device manufactured by Shimadzu Corporation can be used. The measurement was carried out by setting 2.0 mg of the sample in a DSC measuring device (temperature at the start, 40 ° C), setting the holding temperature at 300 ° C, melting for 5 minutes, and rapidly cooling in liquid nitrogen. The rapidly cooled sample was heated at 10 ° C /min, and the peak top temperature of the endothermic peak was measured as the melting points Tm1 and Tm2. The measurement was performed twice (N=2), and the average was graphically represented.

Referring to Fig. 3, two melting points of the low melting point Tm1 and the high melting point Tm2 were measured as melting points. The low melting point Tm1 is about 75 to 80 ° C, the high melting point Tm2 is about 245 to 255 ° C, and the high melting point Tm2 is a value close to the melting point of a usual polyester resin. Therefore, in the flat portion 15 (including the opening 14) in the film layer 10, the polyester resin used for the surface layer 11 is mixed with the modified polyester resin used for the inner layer, and it can be confirmed that the film is relatively low. The temperature seals the fibrous layer 13 to the film layer 10.

The present invention has been described above with reference to the embodiments, but the present invention is not limited thereto, and various modifications can be made. For example, in the illustrated example, although the opening 14 does not penetrate the fiber layer 13, a part or all of the plurality of openings 14 may penetrate the fiber layer 13. Further, although the inner layer 12 and the surface layer 11 are laminated only on one surface of the fiber layer 13, the inner layer 12 and the surface layer 11 may be laminated on both surfaces of the fiber layer 13. At this time, the opening 14 and the recess 16 may be disposed on both surfaces of the fiber layer 13, or may be disposed on only one surface.

1‧‧‧Absorbable flakes

14‧‧‧Opening

10‧‧‧film layer

12‧‧‧ inner layer

11‧‧‧ surface layer

16‧‧‧ recess

15‧‧‧ Flat Department

13‧‧‧Fiber layer

Y‧‧‧2nd direction

X‧‧‧1st direction

Claims (11)

An absorbent sheet for a microwave oven comprising: a film layer on which a food is placed; and an absorbent sheet for a microwave oven capable of absorbing a fiber layer of the juice escaping from the food product, wherein the film layer has a polyester a surface layer, an inner layer made of polyester between the surface layer and the fiber layer, and a plurality of openings penetrating the surface layer and the inner layer, wherein the inner layer is made of an epoxy having two or more functions. The polyester is modified by the base compound, and the film layer and the fiber layer are bonded to each other at least in part. The absorbent sheet for a microwave oven according to the first aspect of the invention, wherein the film layer has a flat portion and a plurality of concave portions located between the flat portions, and the plurality of openings are located in the flat portion. The absorbent sheet for a microwave oven according to the second aspect of the invention, wherein the plurality of openings are further located in the concave portion. The absorbent sheet for a microwave oven according to the second or third aspect of the invention, wherein the film layer and the fiber layer are joined to each other only in the concave portion, and the film layer and the fiber layer are mutually in the flat portion. separable. The absorbent sheet for a microwave oven according to the second aspect of the invention, wherein the ratio of the area of the flat portion to the surface area of the film layer is in the range of 30 to 70%. The absorbent sheet for a microwave oven according to any one of the items 1 to 3, further comprising: a first direction and In the second direction intersecting, the diameter of the opening is 0.5 mm to 3.0 mm, and the plurality of openings are disposed apart from each other in the first direction and the second direction, and the separated dimension in the first direction or the second direction It is 3.0mm~20.0mm. The absorbent sheet for a microwave oven according to the second or third aspect of the invention, wherein the concave portion is a concave groove extending linearly. The absorbent sheet for a microwave oven according to any one of the first aspect of the present invention, wherein the fiber layer comprises a core fiber having a melting point of 200 ° C or more in a pulp fiber, a ray fiber, a polyester fiber or a sheath portion. At least one type of fiber selected from the group consisting of thermoplastic fibers. The absorbent sheet for a microwave oven according to any one of the first to third aspect, wherein the thickness of the flat portion of the fiber layer is larger than a thickness of the concave portion of the fiber layer. The absorbent sheet for a microwave oven according to any one of the first aspect of the invention, wherein the fiber density of the concave portion of the fiber layer is higher than the fiber density of the flat portion of the fiber layer. The absorbent sheet for a microwave oven according to the second or third aspect of the invention, wherein the film layer has a high melting point portion and a low melting point portion in the flat portion.