JPS63130017A - Container for electronic oven - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Industrial field of application The present invention relates to a container for an oven/microwave range◇
More specifically, unexploded aA retains its full rigidity as a container in the temperature range from room temperature to around 200°C,
Moreover, it has excellent heat retention properties for cooked foods and is inexpensive. This product relates to food containers that can be used in cooking appliances such as microwave ovens, microwave ovens/ranges, and gas ranges.

Conventional technology In recent years, with the diversification of eating habits, the increasing number of housewives working, and the advancement of food packaging technology, home-cooked foods that use metal, such as microwave ovens, microwave ovens, and gas ranges, have become widely used. It's starting to look like this.

Conventionally, the packaging of such prepared foods has been either boil-in-bags for reheating the cooked foods such as curries, stews, ha/vada, etc., or for freezing these foods and then removing them from the packaging container when needed. Packaged products that can be taken out and cooked are commercially available.

On the other hand, recently, crystallized polyethylene terephthalate sheets with good heat resistance, mixed resin sheets of polyethylene terephthalate and polyetherimide (for example,
37161), polyetherimide sheets (e.g. Japanese Patent Laid-Open No. 59-51819), packaging materials that can be completely molded and used for open cooking have been developed. It is attracting attention as a heat-resistant packaging container material for cooked foods that require all cooking temperatures.

Problems to be Solved by the Invention However, all of the heat-resistant containers using these materials are thin C-H molded with a thickness of about 0.3 to 0.5 nm, and cannot be used as containers at room temperature or frozen storage temperature. Although it has sufficient rigidity, it softens and loses its rigidity at cooking temperatures of around 200°C, and when the container is taken out and transported after cooking, there are disadvantages such as deformed or sometimes damaged soot. are doing.

If an attempt is made to increase the wall thickness of the sheet in order to overcome all of these drawbacks, although the above-mentioned thermal deformation can be prevented, the molding cycle during container manufacturing will become longer, and the back-end cost will inevitably increase. The problem arises that it is difficult to adopt industrially. In addition, since these sheet-molded containers are made of thin resin sheets, they easily cool down after cooking, and although they are good as cooking containers, they are not necessarily sufficient as tableware. To provide an oven/microwave container that improves the drawbacks of plastic containers, maintains all the rigidity of the container in the temperature range from room temperature to around 200°C, has excellent heat retention for cooked foods, and can be supplied at a low price. It is something that is done for all purposes.

Means for Solving the Problems The inventors of the present invention determined to develop an oven/microwave container with the above-mentioned excellent characteristics, and as a result of intensive research, they developed a container with a specific expansion ratio as a base material for the container. By using a foamed sheeter mainly composed of polyetherimide having a thickness and thickness, the object was achieved and the scales and gold were formed. Based on this knowledge, the present invention was completed.

That is, the present invention provides a container formed by forming a foamed sheet containing polyetherimide as a main component, in which the foaming ratio of the base material is within the range of 2 to 25 times, and the thickness is within the range of the foaming ratio overall horizontal axis, All oven/microwave containers characterized by being located in an area greater than or equal to a straight line connecting one point (zs, 0.as) and point (2,0,2) in orthogonal coordinates with thickness as the vertical axis. This is what we provide.

The present invention will be explained in detail below.

The polyetherimide used in the container of the present invention includes:
(general formula is a group or an alkoxy group), -2- is O, or -
s-, q are 0 or l, y is an integer of 1 to 5); -R- is an aromatic hydrocarbon group having 6 to 20 carbon atoms or a halogenated derivative thereof; , carbon number 2
~20 alkylene group or cycloalkylene group, polydiorganosiloxy group terminal-terminated with an alkylene group having 2 to 8 carbon atoms, where X is an integer of 1 to 5];
n is larger than 1 and has a value such that the intrinsic viscosity of the polyetherimide is 0.1 or more, preferably 35 or more.

This polyetherimide can be prepared by a known method (U.S. Pat.
, No. 803.085, No. 3,838,097, No. 3.
No. 847.867, No. 3, No. 983, No. 093, No. 3
, No. 989,670, No. 3,991,004, No. 4,
No. 293,683, etc.).

Among the above-mentioned polyetherimides, those having a glass transition temperature of 190° C. or higher are particularly preferable because they have excellent rigidity and heat retention properties at high temperatures and are less susceptible to thermal deformation.

The polyetherimide used in the present invention may contain other resins such as polysulfone, polyethersulfone, polyamideimide, polyphenylene oxide, It is also possible to blend all materials such as polycarbonate and polyester.

The container of the present invention is obtained by completely molding a foamed sheet made entirely of the polyetherimide. The foam sheet can be prepared by a known method (for example, JP-A-61-12614).
6)).

In particular, it has a uniform expansion ratio, thickness, cell diameter, and cell size distribution obtained by supplying a foaming composition containing a blowing agent to an extruder and extruding it into a low pressure region from a slit-shaped mouthpiece to foam it. Foamed sheets are preferably used.

Well, when extruding and foaming, it foams from the first cap and immediately after foaming.

A foamed sheet with a skin may also be used, in which the surface of the foamed sheet is brought into full contact with the mold, and a thin resin layer or a low foaming layer with an expansion ratio of less than 2 times is formed on the surface layer of the foamed sheet.

The foaming ratio and thickness of the foamed sheet used for molding the container may be selected so that the foaming ratio and thickness after thermoforming into the container are within the range of the present invention, and the foaming ratio and thickness of the desired container base material may be selected. , is appropriately selected depending on the molding conditions. Normally,
Foaming ratio and thickness.

The foam sheet used is 20 to 30 times larger than that of the container base material.

In the container of the present invention, the foaming ratio of the base material constituting the entire container is within the range of 2 to 25 times, and the thickness is expressed in orthogonal coordinates where the horizontal axis is the foaming ratio and the vertical axis is the thickness Cm)'fr.
It must be in the area above the straight line connecting the point (25,0,35) and the point (2°0.2).A container made of a base material with an expansion ratio of more than 25 times has a high rigidity at high temperatures. The drawback is that it is small, easily deformed by heat, and easily damaged during handling, while those less than twice the size have poor heat retention.

Further, if the thickness is in the region below the straight line in the coordinates, not only is the heat retention property inferior, but also the rigidity at high temperatures is inferior, and it is likely to be thermally deformed. In particular, the thickness is at one point (25,0,358 (25,5), (2,0
, 2) and (2, 2) are preferable because they have a short molding cycle, have excellent deep drawability, and are suitable for industrial production.

The container of the present invention is produced by shallow drawing or deep drawing by using a vacuum forming machine, a pressure forming machine, or a forming machine using a combination of vacuum and compressed air to form a foamed sort made entirely of polyetherimide with a desired expansion ratio and thickness. It can be manufactured by forming into a drawer. There is no particular restriction on the shape of the container, and it may be tray-shaped or three-dimensional.

'1. If desired, paper, resin film, resin sheet, etc. may be laminated and molded at the same time when molding into the foamed metal container, or these may be pasted onto the foamed material with adhesive in advance. The combined laminated sheet kumquat may be molded.

The molding conditions are selected depending on the expansion ratio, thickness, drawing ratio, shape, etc. of the foam sheet, but in general,
The foam sheet is heated at a temperature ranging from room temperature to 330°C, preferably from 80 to 270°C, for about 1 to 180 seconds, fixed in a mold, and then heated in a vacuum or at a temperature of 1 to 15 KP/mold.
A method is used in which the material is molded in close contact with a mold using an air pressure of approximately 200 m.

Effects of the Invention The oven/microwave container of the present invention is made of a base material mainly composed of polyetherimide having a specific expansion ratio and thickness, and the container can be used in a temperature range from room temperature to around 200°C. It maintains its rigidity and has excellent heat retention properties for cooked foods, making it suitable for use in cookers such as microwave ovens, microwave ovens/ranges, and gas ranges.Furthermore, it has low manufacturing costs, making it a practical product. It is of excellent value.

EXAMPLES Next, the invention will be explained in more detail with reference to examples, but the present invention is not limited to these examples in any way.

In addition, each physical property was calculated|required by the following method.

(1) Glass transition temperature The endothermic onset temperature of the endothermic curve measured using a PerkinElmer differential scanning calorimeter DsC-2 model at a sample temperature of 10H12 and a heating rate of 20°C/min in accordance with the method described in ASTM D3418. was determined by extrapolation, and this temperature was taken as the gold glass transition temperature.

(2) Thickness of Container Base Material The thickness was determined to the nearest μm by using a dial gauge type minute thickness measuring device manufactured by Toyo Seiki Nosaku Shin, and rounded to the nearest 10 μm. Measure the bottom and side walls of the container at three points each and use the average value.

(3) Expansion ratio of container base material Samples were cut out from three locations on the bottom and side walls of the foamed container, their weight i- was measured up to the cape, their volume was measured using the water immersion method, and the density ( f/ctIl) was calculated using the following formula from the separately determined density of the base resin, and the average value was shown.

(4) Heating deformation of the container A tray of length 13cP, width 18cm, depth 3F is formed using a full vacuum forming machine, the macaroni gratin is filled on this tray to the depth of the whole tray, and placed in a household gas oven at 230℃.
After cooking for 20 minutes, the tray was immediately removed from the oven, the shape of the tray was observed, measured, and evaluated using the following criteria.

◎The dimensions of Nidorei do not change much.

○There is a slight change in the dimensions of Nidorei, but the shape is the same as the original.

Significant dimensional changes in ΔNidrei were observed, and the shape was also distorted.

×The size of the Nidrei has changed significantly, some of the contents have overflowed, or the shape has changed so much that the original shape cannot be secured.

(5) Rigidity of Container After cooking using the method described in (4) above, the container was immediately taken out of the oven and evaluated using the following criteria.

01 Can be taken out with a cantilever.

02 Cantilever is deformed and 9 can be removed by holding both ends of the tray with one hand.

X: It deforms even if you hold both ends with both hands (6) Heat retention Place the tray cooked using method (4) above on a wooden stake in a room controlled at 20 degrees Celsius, and after 30 minutes All temperatures of the contents were measured and evaluated based on the following criteria.

O: The temperature of the contents is the same at the center and bottom. Δ: Temperature at the bottom of the contents decreases slightly.

X: The temperature at the bottom of the contents is close to the ambient temperature, and the temperature at the center is significantly lower.

Example 1 Polyetherimide obtained from 2.2-bis[:4-(3,4-dicarboxyphenoxy]phenyl]propanedianhydride and m-phenylenediamine (
Made by General Electric Company, Ultem 1020% (glass transition temperature: 216°C), approximately 1 m in diameter.

A pellet having a length of about 1.511 mm was placed in a pressure-resistant container, and acetone was added thereto and heated at 70° C. for 72 hours to impregnate 100 parts by weight of polyetherimide with 13 parts by weight of acetone. The obtained foamable resin composition was supplied to an extruder having a total diameter of 40 nm, heated to 190° C., and extruded into the atmosphere through a slit-shaped mouthpiece provided at the exit of the extruder to cause foaming. At this time, a plate-shaped mold for pressing the foam sheet from above and below was attached to the tip of the slit-shaped mouthpiece, and a uniform foam sheet with a thickness of 2.2 fi was obtained in contact with the surface of the foam sheet. The obtained foam sheet has a magnification of 20 times, a thickness of 2.2, and a cell diameter of 0.3.
0. The closed cell ratio was 95%.

When using this foam sheeter vacuum forming machine, the temperature is 260℃.
After preheating for 15 seconds with
A tray with a depth of 1 and 3 crn was molded. The performance of this tray was completely evaluated, and as shown in the attached table, it was found to have excellent rigidity with no heat deformation, and excellent heat retention. Also,
Trays molded from foam sheets with a thickness of 1.3 mm obtained by changing the opening degree of the mouthpiece also showed excellent performance.

Example 2 The foamable resin composition obtained in Example 1 was left in the air,
A composition with an acetone impregnation amount of 8 parts by weight was supplied to an extruder, heated to 190°C, and extruded and foamed. The shape of the die at the tip of the extruder and the foam sheet mold were completely changed to produce different thicknesses. Four types of foam sheeters were obtained. All of the foamed notebooks obtained were uniform sheets with a cell diameter of about 0.31 tx and a closed cell ratio of 95% or more. These sheets were molded into tray metals in the same manner as in Example 1, and their performance was fully evaluated.

All showed excellent performance. The results are shown in the attached table.

Example 3 Polyetherimide (Ultem 1020, manufactured by General Electric Co., Ltd.) with a diameter of 0.5 mm and a length of 2 mm was placed in a pressure-resistant container, and dichlorotetrafluoroethane/acetone (10/90 TLl) was poured into a pressure-resistant container. Ratio) a) Combined blowing agent gold was heated to 80°C and immersed.

The resulting foamable resin composition contained 5 parts by weight of a blowing agent per 100N parts of resin. This is all example 1
The mixture was fed to an extruder similar to the above and foamed at 190°C to obtain a whole foamed sheet. Foamed notebooks of various thicknesses were made with different opening and sound quality of the orifice, and these were completely vacuum formed and the performance of the companion containers was evaluated.

The results are shown in the attached table. All showed excellent performance〇Comparative Example 1 In Example 1, except for the foaming temperature of 200°C,
A foamed sheet was obtained under the same conditions as in Example 1.

The obtained foam sheet has a thickness of 2.3 xx and a magnification of 28.
The cell diameter was approximately 0.3 tx, and the closed cell ratio was 95%. The performance of the tray vacuum-formed using the same method as in Example 1 was as shown in the attached table, with deformation due to heating and poor rigidity.

Comparative Examples 2 to 4 Polyetherimide (General Electric Co., Ltd., Ultem 1020) 50 Dissolved in Pi dichlororum 200- to explode the dope, and uniformly coated on a polyester film using a 600μ doctor knife.
Dry to a thickness of 80 mm while suppressing the evaporation of chloroform.
A full film of μ was obtained.

The amount of chloroform in the obtained film was 21 parts per 100 parts of resin. This film was heated in a hot air circulation dryer at 200°C for 10 minutes to achieve a foaming ratio of 18.
A foamed sheet 1 with a thickness of 0.22111 times was obtained.

After further drying, films containing 5 parts by weight and 3 parts by weight of chloroform were prepared.
Heat to 00°C and foam to 0°C. For the triple-layered Coroform film, approximately 22 sheets are stacked and pressed and heated in advance with a press, then cooled while being pressed to yield approximately 1.6
The fl sheet was completely heated and foamed. The resulting foamed sheet was vacuum formed into a tray, and its performance was fully evaluated. Each is shown in the separate table.

As is clear from the table, the oven/range container of the present invention does not undergo heat deformation, can be taken out as is after cooking, has excellent rigidity, and has excellent heat retention.

Example 4 In Example 2, the temperature of the mold attached to the outlet of the orifice mouthpiece was set to 130° C., and the surface of the foamed sheet was cooled to perform extrusion foaming. The obtained foam sheet has a magnification of 10 times,
A magnification of 1 is applied to both surface layers of a foam sheet with a thickness of approximately 5H.
．． It was a composite foam sheet having a skin layer with a thickness of 4 times and a thickness of 0.05111. The tray formed by this foam sheet full vacuum forming machine has a skin layer with a magnification of 1.4 times and a thickness of 0.05M on both surface layers of a foam sheet with a magnification of 10 times and a thickness of 4 mm, and a container. In terms of performance, there was no dimensional change in the tray, no deformation due to heating, excellent rigidity that allowed handling after cooking with a cantilever structure, and excellent heat retention.

Example 5 In Example 1, the temperature of the mold was set to 130° C., and 7 layers were formed on the surface of the foam sheet, and the foam sheet was formed at a foam magnification of 20 times and a thickness of 1.3 mm on both surface layers. A composite foam sheet with a foaming ratio of 1.7 times and a skin layer of 0.05 rug thickness? Obtained. The tray formed by this sheet full-vacuum forming machine has skin layers with a magnification of 1.7 times and a thickness of 0.051H on both surface layers of a foamed sheet with a magnification of 20 times and a thickness of 1.2 inches, respectively. Almost no heating deformation was observed.
It had excellent rigidity, could be handled on a cantilever, and had excellent heat retention.

[Brief explanation of the drawing]

The meat side is a graph showing the range of foamed 7-t used in the present invention.

Claims (1)

[Claims] 1. A container formed from a foamed sheet containing polyetherimide as a main component, wherein the base material has an expansion ratio of 2 to 2.
5 times, and the thickness is at the point (25,0
, 35) and the point (2, 0, 2). 2 The foaming ratio and thickness (mm) of the container base material are expressed at the point (25, 0
, 35), point (25, 5), point (2, 0, 2) and point (
2. The oven range container according to claim 1, which is located in the area surrounded by 2). 3. The oven/microwave container according to claim 1 or 2, wherein the foam sheet is made of a resin whose main component is polyetherimide having a glass transition temperature of 190° C. or higher.