Heatable package of food

Claim 2

A HEATABLE PACKAGE OF FOOD COMPRISING A FOOD PRODUCT ENCASED IN A PACKAGING CONTAINER, SAID PACKAGING CONTAINER BEING COMPOSED OF AT LEAST ONE SHEET MATERIAL COMPRISING A METAL SHEET HAVING A THICKNESS OF 5 TO 500 MICRONS AND A PROTECTING COATING LAYER OF HEAT RESISTANT RESIN FORMED ON AT LEAST THE INNER FOOD CONTACTING SURFACE OF SAID METAL SHEET, SAID PROTECTING LAYER BEING COMPOSED OF A POLYIMIDE IMIDAZOPYRROLONEIMIDE HAVING A THICKNESS OF 1 TO 10 MICRONS.

Claim 3

A heatable package of food set forth in claim 1, wherein said polyimide imidazopyrrolone-imide consists essentially of (A) recurring units of polyimide and (B) recurring units of polyimidazopyrrolone-imide, the molar ratio of (A) units/(B) units being within a range of from 1/9 to 9/1.

Claim 4

A heatable package of food set forth in claim 1, wherein said polyimide imidazopyrrolone-imide consists essentially of the recurring unit having the following formula:

Claim 5

A heatable package of food set forth in claim 1, wherein said polyimide imidazopyrrolone-imide has a ring closure ratio of from 50 to 95 percent, defined by the following formula: ring closure ratio (%) 100 X A/B wherein A stands for the value expressed by the formula (logI/Io) 1776 cm /(logI/Io) 1550 cm 411 obtained with respect to the sample to be tested, and B stands for the value expressed by the formula (logI/Io) 1776 cm /(logI/Io) 1500 cm obtained with respect to the sample obtained by heating the sample to be tested until increase of the imide ring was not detected any more, and I stands for the percent transmission Of the resin at the indicated wavelength and Io stands for the percent transmission of the background at the same wavelength.

Claim 6

A heatable package of food comprising a food product encased in a packaging container, said packaging container being composed of at least one sheet material comprising a metal sheet having a thickness of 5 to 500 microns and a protecting coating layer of heat resistant resin formed on at least the inner food contacting surface of said metal sheet, said protecting coating layer having a thickness of 1 to 10 microns and being composed of a blend composition of (A) a polyimide imidazopyrrolone- imide and (B) a polyamideimide or polyamideimide ester at a mixing weight ratio of (A) : (B) ranging from 1 : 0.06 to 1 : 25.

Claim 7

A heatable package of food comprising a food product encased in a packaging container, said packaging container being composed of at least one sheet material comprising a metal sheet having a thickness of 5 to 500 microns and a protecting coating layer of heat resistant resin formed on at least the inner food contacting surface of said metal sheet, said protecting coating layer having a thickness of 1 to 10 microns and being composed of a blend composition of (A) a polyimide imidazopyrrolone- imide and (B) a polyamideimide or polyamideimide ester at a mixing weight ratio of (A) : (B) ranging from 1 : 0.06 to 1 : 25.

Claim 8

A heatable package of food which comprises a food product encased in a sealed bag composed of two flexible sheet materials, said bag being sealed at all end portions thereof, each flexible sheet material comprising a metal sheet having a thickness of 5 to 100 microns and protecting coating layers of heat resistant resin having a thickness of 1 to 10 microns formed on the inner food contacting surface and the outer surface of said metal sheet, said heat resistant resin being selected from the group consisting of (1) a polyimide imidazopyrroloneimide consisting essentially of (A) recurring units of polyimide and (B) recurring units of polyimidazopyrroloneimide, the molar ratio of (A) units/ (B) units being within a range of from 1/9 to 9/1, and (2) a blend composition of (a) a polyimide imidazopyrrolone-imide and (b) a polyamideimide or polyamideimide ester at mixing weight ratio of (a) : (b) ranging from 1 : 0.06 to 1 : 25, each of the said sealed end portions of the bag being formed by a heat seal thermoplastic resin selected from the group consisting of polyamides and polyester, said heat seal thermoplastic resin layer being disposed in contact with said protective coating layers.

Claim 9

A heatable package of food which comprises a food product encased in a sealed bag composed of two flexible sheet materials, said bag being sealed at all end portions thereof, each flexible sheet material comprising a metal sheet having a thickness of 5 to 100 microns and protecting coating layers of heat resistant resin having a thickness of 1 to 10 microns formed on the inner food contacting surface and the outer surface of said metal sheet, said heat resistant resin being selected from the group consisting of (1) a polyimide imidazopyrroloneimide consisting essentially of (A) recurring units of polyimide and (B) recurring units of polyimidazopyrroloneimide, the molar ratio of (A) units/ (B) units being within a range of from 1/9 to 9/1, and (2) a blend composition of (a) a polyimide imidazopyrrolone-imide and (b) a polyamideimide or polyamideimide ester at mixing weight ratio of (a) : (b) ranging from 1 : 0.06 to 1 : 25, each of the said sealed end portions of the bag being formed by a heat seal thermoplastic resin selected from the group consisting of polyamides and polyester, said heat seal thermoplastic resin layer being disposed in contact with said protective coating layers.

Claim 10

A heatable package of food which comprises a food product encased in a sealed bag composed of two flexible sheet materials, said bag being sealed at all end portions thereof, each flexible sheet material comprising a metal sheet having a thickness of 5 to 100 microns and protecting coating layers of heat resistant resin having a thickness of 1 to 10 microns formed on the inner food contacting surface and the outer surface of said metal sheet, said heat resistant resin being selected from the group consisting of (1) a polyimide imidazopyrroloneimide consisting essentially of (A) recurring units of polyimide and (B) recurring units of polyimidazopyrroloneimide, the molar ratio of (A) units/(B) units being within a range of from 1/9 to 9/1, and (2) a blend composition of (a) a polyimide imidazopyrrolone-imide and (b) a polyamideimide or poylamideimide ester at mixing weight ratio of (a) : (b) ranging from 1 : 0.06 to 1 : 25, each of the said sealed end portions of the bag being formed by an adhesive which is disposed in contact with said protective coating layers, the said adhesive being composed of a thermosetting resin selected from the group consisting of epoxy resins and polyurethane resins, one of the said flexible sheet materials being provided with an opening for packing a food product at the upper part thereof, a sealing flexible sheet consisting of a metal foil having on one surface a protective coating layer and having on the other surface a heat-sealable resin layer being applied so as to cover completely said opening, said heat-sealable resin layer of said sealing flexible sheet being melt-bonded to the said protecting coating layer of the heat resistant resin of said flexible sheet material.

Claim 11

A heatable package of food which comprises a food product encased in a sealed bag composed of two flexible sheet materials, said bag being sealed at all end portions thereof, each flexible sheet material comprising a metal sheet having a thickness of 5 to 100 microns and protecting coating layers of heat resistant resin having a thickness of 1 to 10 microns formed on the inner food contacting surface and the outer surface of said metal sheet, said heat resistant resin being selected from the group consisting of (1) a polyimide imidazopyrroloneimide consisting essentially of (A) recurring units of polyimide and (B) recurring units of polyimidazopyrroloneimide, the molar ratio of (A) units/(B) units being within a range of from 1/9 to 9/1, and (2) a blend composition of (a) a polyimide imidazopyrrolone-imide and (b) a polyamideimide or poylamideimide ester at mixing weight ratio of (a) : (b) ranging from 1 : 0.06 to 1 : 25, each of the said sealed end portions of the bag being formed by an adhesive which is disposed in contact with said protective coating layers, the said adhesive being composed of a thermosetting resin selected from the group consisting of epoxy resins and polyurethane resins, one of the said flexible sheet materials being provided with an opening for packing a food product at the upper part thereof, a sealing flexible sheet consisting of a metal foil having on one surface a protective coating layer and having on the other surface a heat-sealable resin layer being applied so as to cover completely said opening, said heat-sealable resin layer of said sealing flexible sheet being melt-bonded to the said protecting coating layer of the heat resistant resin of said flexible sheet material.

Claim 12

A heatable package of food set forth in claim 7, wherein the metal sheet is an aluminum sheet.

Claim 13

A heatable sealed package of food comprising a precoOked food product encased in a packaging container, said packaging container consisting of a can comprising a tube-like can shell provided with flange members at the opposite ends thereof, can end members, and seamed portions formed between each flange member of the can shell and the respective end member, said can shell being formed by lapping both side edges of a plate-like metal blank and lap-bonding them by heat fusion of a thermoplastic resin interposed between the confronting surfaces of both side edges of the metal blank, said plate-like metal blank having at least on the inner food contacting surface of the can shell a protective coating layer of heat resistant resin having a thickness of 1 to 10 microns, and said confronting surfaces of the side edges of the plate-like metal blank being lap-seamed by heat fusion of a layer of a thermoplastic resin selected from the group consisting of polyamides and polyesters, which is disposed in contact with said protective coating layer said heat resistant resin being selected from the group consisting of (1) a polyimide imidazopyrrolone-imide consisting essentially of (A) recurring units of polyimide and (B) recurring units of polyimidazopyrrolone-imide, the molar ratio of (A) units/(B) units being within a range of from 1/9 to 9/1, and (2) a blend composition of (a) a polyimide imidazopyrrolone-imide and (b) a polyamideimide or polyamideimide ester at mixing weight ratio of (a) : (b) ranging from 1 : 0.06 to 1 : 25.

Claim 14

A heatable sealed package of food comprising a precoOked food product encased in a packaging container, said packaging container consisting of a can comprising a tube-like can shell provided with flange members at the opposite ends thereof, can end members, and seamed portions formed between each flange member of the can shell and the respective end member, said can shell being formed by lapping both side edges of a plate-like metal blank and lap-bonding them by heat fusion of a thermoplastic resin interposed between the confronting surfaces of both side edges of the metal blank, said plate-like metal blank having at least on the inner food contacting surface of the can shell a protective coating layer of heat resistant resin having a thickness of 1 to 10 microns, and said confronting surfaces of the side edges of the plate-like metal blank being lap-seamed by heat fusion of a layer of a thermoplastic resin selected from the group consisting of polyamides and polyesters, which is disposed in contact with said protective coating layer said heat resistant resin being selected from the group consisting of (1) a polyimide imidazopyrrolone-imide consisting essentially of (A) recurring units of polyimide and (B) recurring units of polyimidazopyrrolone-imide, the molar ratio of (A) units/(B) units being within a range of from 1/9 to 9/1, and (2) a blend composition of (a) a polyimide imidazopyrrolone-imide and (b) a polyamideimide or polyamideimide ester at mixing weight ratio of (a) : (b) ranging from 1 : 0.06 to 1 : 25.

Claim 15

A heatable package of food which comprises a food product encased in a container said packaging container consisting of an open container member provided with a food-encasing portion and a flange member formed along the periphery of the food-encasing portion, and a lid member composed of a sheet material closing said container members, said container member consisting of a metal sheet having a thickness of 50 Mu to 500 Mu and a protective coating layer, formed at least on the inner food contacting surface of the metal sheet, of a heat resistant resin having a thickness of 1 Mu to 10 Mu , and a sealed portion is formed between the flange member of said container member and said lid member by heat sealing of a layer of a thermo-plastic resin selected from the group consisting of polyamides and polyesters which is disposed in contact with the protective coating layer of said container member, said heat resistant resin being selected from the group consisting of (1) a polyimide imidazopyrroloneimide consisting essentially of (A) recurring units of polyimide and (B) recurring units of polyimidazopyrroloneimide, the molar ratio of (A) units/(B) units being within a range of from 1/9 to 9/1, and (2) a blend composition of (a) a polyimide imidazopyrrolone-imide and (b) a polyamideimide or polyamideimide ester at mixing weight ratio of (a) : (b) ranging from 1 : 0.06 to 1 : 25.

Claim 16

A heatable package of food which comprises a food product encased in a container said packaging container consisting of an open container member provided with a food-encasing portion and a flange member formed along the periphery of the food-encasing portion, and a lid member composed of a sheet material closing said container members, said container member consisting of a metal sheet having a thickness of 50 Mu to 500 Mu and a protective coating layer, formed at least on the inner food contacting surface of the metal sheet, of a heat resistant resin having a thickness of 1 Mu to 10 Mu , and a sealed portion is formed between the flange member of said container member and said lid member by heat sealing of a layer of a thermo-plastic resin selected from the group consisting of polyamides and polyesters which is disposed in contact with the protective coating layer of said container member, said heat resistant resin being selected from the group consisting of (1) a polyimide imidazopyrroloneimide consisting essentially of (A) recurring units of polyimide and (B) recurring units of polyimidazopyrroloneimide, the molar ratio of (A) units/(B) units being within a range of from 1/9 to 9/1, and (2) a blend composition of (a) a polyimide imidazopyrrolone-imide and (b) a polyamideimide or polyamideimide ester at mixing weight ratio of (a) : (b) ranging from 1 : 0.06 to 1 : 25.

Claim 17

A heatable package of food set forth in claim 10, wherein the metal sheet is a steel plate.

Claim 18

A heatable package of food set forth in claim 10, wherein the metal sheet is a steel plate having a chromium oxide film in an amount, reckoned as metallic chromium, of 50 to 1,500 Mu g/dm2.