TWI579205B - Heat-resistant food container and its manufacturing method - Google Patents

Description

Heat resistant food container and method of manufacturing same

The present invention relates to a heat-resistant food container, and more particularly to a heat-resistant food container which is also subjected to a conditioning temperature of a temperature of 180 to 250 ° C which is heated and regulated by a microwave oven.

In food stores such as convenience stores, department stores, and supermarkets, various foods such as side dishes, fried foods, noodles, and salads are placed in food containers such as trays, cups, and bowls for sale. The heat resistance of the food containers is required to reach a temperature (90 ° C) at which the microwave oven receives a food having a small oil content, and a microwave oven heated at a temperature (150 ° C) for receiving a food having a large oil content, and the milk is roasted. (gratin), heat resistance of the coking temperature (180 to 250 ° C) such as cheese. A food container having heat resistance of up to 90 to 150 ° C has been proposed to be composed of four layers of A, B, C, and D from the inside, and a thickness of 20 to 60 in the outer layer of the D layer. A container in which a PP layer of an inorganic filler is added to heat resistance (see Patent Document 1), or a mixture of 10% by weight or more of a PP resin and a PE resin, 40 to 80% by weight, and talc 20 to 60% by weight. tree A technique for forming a fat composition (see Patent Document 2). However, the container formed by these techniques uses a PP resin as a main component, and the melting point of the PP resin is about 160 ° C. Therefore, it is not possible to use a container having heat resistance to 250 ° C corresponding to milk roast.

In the case of a container having heat resistance of up to 180 to 250 ° C, a shaped container using a C-PET resin (addition of a crystal promoter) is generally used.

In addition, a repeating unit has been proposed:

The mixture is formed by mixing a mixture of 25 to 500 parts by weight of an inorganic compound with respect to 100 parts by weight of the wholly aromatic polyester forming the optically anisotropic melt phase, and is compatible with an oven up to -40 to 250 ° C. Container (refer to Patent Document 3).

In addition, a method of producing a sheet for a food container using an undried recycled PET sheet (polyethylene terephthalate sheet) or the like has been proposed (see Patent Document 4), but the sheet for the food container is not heat resistant. Sex.

Prior technical literature Patent literature

Patent Document 1: Japanese Patent Publication No. 9-11419

Patent Document 2: Japanese Patent Laid-Open No. 2-68015

Patent Document 3: Japanese Patent Laid-Open No. Hei 1-171515

Patent Document 4: Japanese Laid-Open Patent Publication No. 11-184580

However, the container formed by using the aforementioned C-PET resin is expensive because the C-PET resin itself is expensive. Further, the above-described container formed using a wholly aromatic polyester is required to re-synthesize a wholly aromatic polyester resin and become expensive. As described above, conventionally, it has a heat resistance of up to 250 ° C, and it is only expensive to withstand the food container which is heated and conditioned by the microwave oven.

The present invention has been made to solve the above problems, and an object thereof is to provide a food product which can be inexpensively produced by using a general PET resin which is inexpensive to use, or a PET resin which is less expensive, or a recycled PET sheet, and which has high heat resistance up to 250 °C. container.

As a result of intensive research, the present inventors have found that a chain extender, a talc, a phase solvent of a PET resin and a talc, which are bonded to the end of the PET resin chain, are mixed with a general PET resin, a PET resin for fibers, a recycled PET sheet, and the like. The mixed resin is put into an extruder having a vent hole, and the vent hole is -99.99 kPa or more in a state of being heated and melted. After vacuuming and degassing, the PET resin of the raw material is not required to be dried, and after being subjected to high molecular weight by a chain extender, the extruded sheet is formed by a thermoforming machine and kept in the forming mold at 100~. The PET resin is crystallized at 220 ° C. When the content of the crystalline portion of the PET resin and the talc is 25% by weight or more, heat resistance of 180 to 250 ° C in the microwave oven can be imparted, so that the present invention can be completed.

In other words, the heat-resistant food container of the present invention is characterized in that a chain extender, a phase solvent, and talc are added to the PET resin, and the main extruder is placed in a vent hole of 2 or more, and the PET resin is heated and melted. After suction and degassing under a high vacuum of -99.99 kPa or more, the vent is formed by extrusion molding, and the sheet is formed into a vacuum/pressure air by a thermoforming machine, and is kept in the forming mold at 100~. The container was formed at 220 ° C, and the total amount of the crystal portion shown by the following formula and the content of the talc in the container was 25% or more.

One aspect of the heat-resistant food container of the present invention is characterized in that the chain extender is one having three or more epoxy groups, and the phase solvent is ethylene/acrylic acid/glycidyl methacrylate copolymer, and the amount of the talc added is It is 2~15%.

Another aspect of the heat-resistant food container of the present invention is characterized in that an inner layer made of a PET resin layer is formed by a co-extrusion method.

Another aspect of the heat-resistant food container of the present invention is characterized in that printing by gravure printing is performed by A-PET film or film stretching 1.5 to 2.5 times in the MD direction by heat bonding. The film is formed into an outer layer.

One aspect of the invention The method for producing a heat-resistant food container is characterized in that a chain extender having three or more epoxy groups, a phase solvent of an ethylene/acrylic acid/glycidyl methacrylate copolymer, and talc 2 are added to a PET resin serving as a main layer. ～15% by weight, and the PET resin which is an inner layer is put into a sub-extrusion machine having a vent hole of 1 or more, and the respective PET resin is heated and melted, After suction and degassing under a high vacuum of -99.99 kPa or more, the main layer and the inner layer are formed by a co-extrusion method, in which the A-PET film or the A-PET film is formed The film in which the MD direction is extended 1.5 to 2.5 times is applied to the outer layer of the gravure printed film, and the laminated layer formed by the inner layer, the main layer and the outer layer is vacuum-pressured by a thermoforming machine by laminating by heat bonding. Air is formed and maintained at 100 to 220 ° C in the forming mold.

The heat-resistant food container of the present invention is formed of a resin composition in which a chain extender, a phase solvent, and talc are added to the PET resin. By adding a chain extender to the PET resin and bonding the ends of the low molecular weight PET molecules, the high molecular weight PET resin having a three-dimensional structure can be modified, and as a result, the melt tension of the PET resin or the recycled PET sheet is used. The resin which is low and cannot be extruded can also increase the melt tension and can be extruded. Further, by adding talc, the heat resistance of the container can be improved, and by adding a phase solvent, the talc can be uniformly dispersed and mixed in the PET resin.

The resin composition of the PET resin is placed in an extruder having a vent hole of 2 or more, and the PET resin is suctioned and degassed under a high vacuum of -99.99 kPa or more by a vent hole in a state of being heated and melted. Since the sheet is formed by extrusion molding, the PET resin can be used without being dried, and the production cost can be reduced. In particular, even if the PET sheet or the like is recovered, it can be used without drying, so that it can be produced at low cost.

Further, the sheet formed by extrusion molding is subjected to vacuum/pressure air forming by a thermoforming machine, and is maintained at 100 to 220 ° C in the molding die, so that the degree of crystallization can be improved. Then, since the total amount of the crystal portion and the talc is 25% by weight or more, the heat resistance is up to 250 ° C, and heating by additional coking such as milk roasting in a microwave oven can be performed.

In one aspect of the heat-resistant food container of the present invention, since the chain extender has three or more epoxy groups, the terminal of the PET molecule can be combined with the epoxy group, and the three-dimensional structure can be efficiently modified. High molecular weight PET resin. Further, since the phase solvent is an ethylene/acrylic acid/glycidyl methacrylate copolymer, it can be dissolved in both the PET resin and the talc, and is extremely uniformly dispersed and mixed, and the talc agglomerate can be substantially completely prevented. In addition, since the amount of talc added is 2 to 15% by weight, the heat resistance itself can be improved, and the knot can be formed into PET. The crystal nucleating agent promotes crystallization and can promote crystallization to the low temperature side more than pure PET.

In another aspect of the heat-resistant food container of the present invention, the inner layer formed of the PET resin layer is formed by the co-extrusion method, and therefore, even in the case where recycled PET sheets or the like are used in the raw material of the main layer, The original PET resin forms an inner layer, which ensures high safety and hygiene and can be used as a food container without any problem.

In other aspects of the heat-resistant food container of the present invention, printing by gravure printing by an A-PET film or a film extending 1.5 to 2.5 times in the MD direction by the A-PET film by heat bonding is formed. The film is formed into an outer layer, so that the appearance of the container can be aesthetically pleasing.

In the method for producing a heat-resistant food container according to an aspect of the present invention, a chain extender having three or more epoxy groups and an ethylene/acrylic acid/glycidyl methacrylate copolymer are added to the PET resin serving as the main layer. 2 to 15% by weight of the phase solvent and talc, and the main extruder is placed in a ventilator having a vent hole of 2 or more, and the PET resin which is an inner layer is placed in a sub-extrusion machine having a vent hole of 1 or more, and the respective PET resins are subjected to In the state of heating and melting, the main layer and the inner layer are formed by a co-extrusion method by suction and degassing under a high vacuum of -99.99 kPa or more, and the main layer is made of A-PET film or The film in which the A-PET film is extended 1.5 to 2.5 times in the MD direction is applied to the outer layer of the gravure printed film, and laminated by heat bonding, and the laminated sheet formed by the inner layer, the main layer and the outer layer is heated. The forming machine performs vacuum/pressure air formation and is maintained at 100 to 220 ° C in the forming mold, so that the above heat resistance can be easily manufactured. As a result of the food container, it is possible to inexpensively produce a heat-resistant food container which is excellent in heat resistance, safety and hygiene, and aesthetics up to 250 °C.

10‧‧‧Quantitative feeder

11‧‧‧Feeder for PET resin

12‧‧‧Chain for chain extender

13‧‧‧phase solvent feeder

14‧‧‧Turquoise feeder

15‧‧‧Pig Feeder

20‧‧‧Mixer

21‧‧‧ body

22‧‧‧turn valve

30‧‧‧Main Extrusion Machine

31‧‧‧ cylinder

32‧‧‧Spiral axis

33, 34‧‧‧ vents

35‧‧‧Pressure compression department

36‧‧‧ Sealing Department

37‧‧‧Exit

40‧‧‧Subjector

41‧‧‧ cylinder

42‧‧‧Spiral axis

43, 44‧‧‧ vents

45‧‧‧Exit

50‧‧‧Feed block

60‧‧‧T-die

70‧‧‧Cooling roller

80‧‧‧Printed film conveying roller

90‧‧‧Winding roller

100‧‧‧heater

111‧‧‧Female model

112‧‧‧Male model

113‧‧‧heater

A‧‧‧ laminated sheets

b‧‧‧Printed film

c‧‧‧Laminated sheets

Fig. 1 is a schematic view showing a manufacturing apparatus for a sheet for a heat-resistant food container.

Fig. 2 is a schematic view showing a cylinder portion of an extruder used in a manufacturing apparatus for a sheet for a heat-resistant food container.

Fig. 3 is a schematic view showing a heating portion of a laminated sheet.

Figure 4 is a schematic view of a thermoforming machine.

Fig. 5 is a graph showing the effect of talc against the crystallization rate of PET.

Fig. 6 is a view showing a curve measured by a differential scanning calorimeter in a mode.

In the heat-resistant food container of the present invention, first, a PET resin material in which a chain extender, talc, and a phase solvent are added and mixed with a PET resin is prepared. In the case of the PET resin, the raw PET resin, the PET resin for fibers, and the recycled PET sheet are not particularly limited. However, it is preferred to use a PET resin for fibers, a recycled PET sheet, or the like because it can be produced at a lower cost.

Chain extenders are used to bind the ends of low molecular weight PET molecules to those of high molecular weight PET resins of the 3-dimensional structure. In the chain extender, it is necessary to have three or more epoxy groups in one molecule, and as the number of epoxy groups increases, the reactivity also increases. "ADR4368S" (BASF Japan) having a highly reactive styrene acrylic acid oligomer (Mn = 3,000) having 9 to 10 epoxy groups in one molecule, as described above. ))Wait.

The amount of the chain extender to be added may be determined according to the performance of the chain extender to be sold, in accordance with the amount of addition specified by each company. The above-mentioned "ADR4368S" is 0.5% by weight based on the PET resin. The recycled PET sheet having a PET resin having an intrinsic viscosity of less than 0.6 is added in an amount of more than 0.5% by weight, and when it is higher than 0.6, the amount of addition is less than 0.5% by weight. When the amount of addition is small as described above, a masterbatch (hereinafter referred to as "MB") is added to the PET resin in an amount of 20 to 40% by weight, and added as MB.

The talc system improves the heat resistance and forms a nucleating agent for crystallization to accelerate the crystallization rate, together with the crystallization portion of the PET resin, the heat resistance is raised to 250 °C.

Fig. 5 shows the crystallization rate of PET when 0.5% by weight of talc (relative to PET) is added, and the crystallization temperature is used for the horizontal axis and the semi-crystallization time is used for the vertical axis. From this figure, adding 0.5% PET of talc, compared with pure PET, the crystallization rate is increased by about 1.5 times even in the range of 150 to 160 ° C, and the difference is 150 ° C or lower. A more substantial increase, it can promote crystallization to the low temperature side more than pure PET.

In general, report on the mechanism of action of nucleating agents added There are few examples, such as the adsorption of PET on the nucleating agent, the increase in the Trans-Conformation of the molecular chain, or the chemical Nucleation by the reaction of the nucleating agent with PET.

In addition to its role as a nucleating agent, talc is also responsible for the task of heat resistance or rigidity enhancement. In other words, PET is made of an amorphous portion and a crystalline portion, and at a temperature higher than the glass transition point (about 70 ° C), the amorphous portion rises at the same temperature as the glass and gradually becomes soft, and the retention force against deformation becomes weak. . On the other hand, the crystal portion is solid until it is melted at a melting point temperature (PET is 260 ° C), and there is no possibility that the holding force for deformation is weak. Talc is also an inorganic material and is also solid at 260 °C. Therefore, in the same action as the crystal of PET, both of them interact to improve heat resistance. The improvement in heat resistance is in the sea of the amorphous portion of PET. The crystalline portion of PET as a solid and the island of talc rise above the glass transition point of PET, even if the amorphous portion is softened and deformed, if the crystal portion There is a large amount of solid portion with talc, and the distance between the solids becomes close. Therefore, even if the amorphous portion is to be softened and deformed, since the solid does not deform, it is considered to be a deformable person.

The amount of the talc added is preferably 2 to 15% by weight, preferably 3 to 10% by weight, based on the PET.

Next, the total amount of the crystal portion represented by the following formula and the content of the talc is finally made 25% by weight or more based on the total weight of the container. By making the total amount 25% by weight or more, heat resistance up to 250 ° C can be secured.

Each of the heats is obtained, for example, from the curve shown in the mode of Fig. 6, and is obtained therefrom.

The average particle diameter of the talc is preferably 20 μm or less, more preferably 10 μm or less. When the average particle diameter exceeds 20 μm, the dispersion is deteriorated, and even if the amount is the same, the amount of the nucleating agent is also small. The lower limit is not particularly limited, but it is usually practical to be 0.5 μm.

Since talc is in the form of a powder, handling is troublesome, and it is formed into agglomerates in the PET resin and is not easily uniformly dispersed, it is preferable to add MB which is a polyethylene (PE) resin. In the case of MB of talc, it is preferred to use a high concentration of 50 to 80% by weight of talc. Since the PE resin is a foreign matter with respect to the PET resin, the amount of the PE resin can be reduced by forming it at a high concentration, and the physical properties of the PET resin can be prevented as much as possible.

The phase solvent is used to uniformly disperse the talc in the PET resin. That is, the talc is preferably added by the MB of the PE resin, and the phase solvent can dissolve the PET resin and the PE resin. As a result, the PET resin and the talc can be dissolved and uniformly dispersed in the PET resin. Therefore, in terms of a phase solvent, an ethylene/acrylic acid/glycidyl methacrylate copolymer belonging to a phase solvent of a polyester and an olefin is preferred.

The amount of the phase solvent to be added is determined by the amount of the amount specified by each company. For example, if it is "LOTADER (registered trademark) AX8840" sold by the company ARKEMA, it may be 4% by weight or less based on the total weight. The lower limit is not particularly limited and is usually up to 1% by weight.

The PET resin material which was uniformly dispersed and mixed as described above was placed in an extruder having a vent hole of 2 or more, and the vent hole was at -99.99 kPa (gauge pressure) or more in a state where the PET resin was heated and melted. After suction and degassing under high vacuum, the sheet is formed by extrusion molding.

After the degassing is performed in the extruder as described above, the extrusion molding is performed, whereby the sheet can be formed without a drying process, so that the cost can be reduced. In other words, when the PET resin is extruded by an extruder, when the PET resin contains water, it is hydrolyzed and deteriorated. Therefore, it is usually necessary to dry it to 50 ppm or less. The drying is carried out at a temperature of 120 to 140 ° C. Although it depends on the amount of water, there are a few hours from the case of the original PET resin to 10 hours in the case of recovering the PET sheet, which is expensive. Energy costs and costs increase. Therefore, the dry-free PET resin or the recycled PET sheet can be directly used as it is without the need of drying, so that the cost required for the drying process can be reduced.

Next, the sheet was formed into a vacuum/pressure air by a thermoforming machine, and held at 100 to 220 ° C in a molding die to form a container. That is, the temperature of the sheet is heated to 80 to 130 ° C, and formed into a container by a vacuum forming machine by vacuum or vacuum/pressure air forming, and kept in the same forming mold for 3 to 10 seconds as 100 to 220. °C, preferably 120 to 200 ° C, is taken out by the mold. The forming mold may be a mold formed by plug assist with a general master mold, or a mold of a so-called male mold in which the master mold and the male mold are similarly shaped. Yin and Yang mode When the mold of the master mold or the male mold is used as a heating mold and the other mold is used as a cooling mold, the crystallization of PET can be promoted by heating the mold at the beginning, and then cooling can be shortened by cooling the mold. The time until the container is removed.

For example, when the male mold is formed to heat the mold, the vacuum port of the male mold is formed into a vacuum, and the pressurized air is blown from the master mold of the cooling mold to form the container. Next, the formed container is brought into close contact with the male mold and heated to 100 to 220 ° C for a predetermined period of time to be held to promote crystallization. Next, the pressurized air is blown from the vacuum port of the male mold, and the vacuum port of the master mold is formed into a vacuum to press the container against the master mold for cooling.

When the master mold is used as a heating mold, the vacuum port of the master mold is formed into a vacuum, and the pressure air is blown from the vacuum port of the male mold to form the container. Next, the formed container is brought into close contact with each other and heated to 100 to 220 ° C for a predetermined period of time to be held to promote crystallization. Next, the vacuum port of the male mold was formed into a vacuum, and the pressurized air was blown from the vacuum port of the master mold to press the container against the male mold for cooling.

As described above, it is maintained at 100 to 220 ° C in the molding die, whereby the total amount of the crystal portion of the container and the talc is 25% by weight or more, preferably 25 to 40% by weight.

Further, the container may be formed only by a PET resin layer in which a chain extender, a phase solvent, and talc are added to the PET resin. However, the PET resin layer may be a main layer and the inside thereof (the side in contact with the food) A layer of a native PET resin is formed as an inner layer. By forming the inner layer, even if the PET resin used for the main layer is a recycled sheet, it can be ensured to be extremely high. Hygienic. When the inner layer is formed, it can be formed at the same time as the main layer by the co-extrusion method. Further, in the inner layer, the sub-extrusion machine having one or more vent holes is used, and the undried PET resin is pushed out while being sucked and degassed by the vent holes, whereby the drying process can be omitted and the production can be performed inexpensively. The thickness of the inner layer is preferably 25 μm to 50 μm. In terms of the ratio to the main layer, it is preferably about 2.5 to 10% of the thickness of the main layer + the inner layer.

Further, a PET resin layer having a chain extender, a phase solvent, and talc may be added to the PET resin, and the A-PET film or the film in which the A-PET film is extended 1.5 to 2.5 times in the MD direction is subjected to gravure printing. The printed film is formed as an outer layer. By forming the outer layer, the appearance of the container surface can be improved. When the outer layer is formed, when the PET resin layer is subjected to extrusion molding, it can be formed by laminating by heat bonding at the same time.

Next, an apparatus for manufacturing a sheet for a heat-resistant food container will be described by the present invention.

1 is a schematic view of a sheet for manufacturing a heat-resistant food container, and FIG. 2 is a schematic view showing a cylinder portion of an extruder used in a manufacturing apparatus for a sheet for a heat-resistant food container, and FIG. 3 is a schematic view showing a heating portion of the laminated sheet. Figure 4 is a schematic view of a thermoforming machine.

In Fig. 1, 10 series quantitative feeder, 20 series mixer, 30 series main extruder, 40 series sub-extruder, 50 series feeding block, 60 series T-die, 70-series cooling roller, 80-series printing Film transport roller, 90-winding roller. The quantitative feeder 10 is composed of a PET resin feeder 11, a chain extender feeder 12, a phase solvent feeder 13, a talc feeder 14, and a pigment feeder 15. , respectively, put the predetermined amount into the mix Machine 20. The mixer 20 is composed of a main body 21 and a rotary valve 22 provided at the lower end, and the materials to be fed by the quantitative feeders 11, 12, 13, 14, 15 are uniformly mixed in the main body 21 to adjust the PET resin material, and The rotary valve 22 is supplied to the main extruder 30 by a predetermined amount. In the main extruder 30, the PET resin material to be charged is heated and melted, and the vent hole is suctioned and degassed under a high vacuum of -99.99 kPa or more, and then pushed out.

A schematic diagram of the cylinder portion of the main extruder 30 is shown in FIG. In FIG. 2, reference numeral 31 denotes a cylinder, and a screw shaft 32 is provided inside the cylinder 31, and a first vent hole 33 and a second vent hole 34 are formed from the base end side (resin input side). The pressurizing and compressing portion 35 and the sealing portion 36 are alternately arranged on the screw shaft 32. The sealing portion 36 narrows the channel width of the screw shaft, and the molten PET resin is filled therebetween to pressurize the back pressure 100 in the pressurizing and compressing portion 35. The high pressure of ~200 kg/cm ² and the high vacuum pressure difference of -99.99 kPa with the vent holes 33 and 34 are sealed, and the resin is propelled only when the screw shaft 32 rotates to prevent the molten PET resin from being sprayed by the vent holes 33, 34. Start.

The vent holes 33 and 34 are connected to an oil rotary vacuum pump through a condenser, and the condensing machine is used to maintain the degree of vacuum and maintain the quality of the oil of the oil rotary vacuum pump. If the coagulation machine is not provided, for example, if the PET resin having a water content of 3,000 ppm is operated at a discharge rate of 500 kg/hr, water vapor of 500,000 g × 0.3/100 = 1,500 g/hr may occur and the high vacuum may not be maintained, and the oil may be rotated. The oil of the vacuum pump will also be mixed with water and deteriorated.

In the extruder shown in the above, when the PET resin is melted and extruded, the PET resin is supplied to the cylinder 31, and the extrusion temperature is about 280 ° C, the back pressure is 100 to 200 kg/cm ² , and the vent holes 33 and 34 are used. The suction and degassing are carried out under a high vacuum of -99.99 kPa or more.

The PET resin to be charged is first blended with the MB of the chain extender which is added by heating and melting, the phase solvent, and the MB of the talc in the first region. The molten PET is depolymerized by hydrolysis or thermal decomposition by water and heat to produce a low molecular weight PET chain, ethylene glycol or acetaldehyde. However, since the addition of the chain extender is carried out, a low molecular weight PET chain is combined, and a polymerization reaction such as high molecular weight of three-dimensional or capture of ethylene glycol or acetaldehyde is started. That is, the epoxy group:

Splitting, in combination with a functional group such as a carboxyl group (-COOH), an aldehyde group (-CHO), or a hydroxyl group (-OH), the PET molecular chain is formed into a three-dimensional network structure of a polymer, and will also be produced by depolymerization. Ethylene glycol, acetaldehyde generated by ethylene glycol is captured as part of the polymer. Further, since the water content contained in the water is 65 kg/cm ² at a saturated water vapor pressure of 280 ° C, it is in a liquid state at a back pressure of 100 kg/cm ² or more.

Then, when the molten PET resin containing ethylene glycol, acetaldehyde or water reaches the first vent hole 33, it is formed to a height of -99.99 kPa or more. Under vacuum, ethylene glycol (boiling point: 198 ° C), acetaldehyde (boiling point: 20 ° C), and water (boiling point: 100 ° C) were formed into a gas, and the first vent hole 3 was sucked and degassed. Next, ethylene glycol, acetaldehyde, and water which have not been completely deaerated by the first vent hole 33 are sucked and degassed by the second vent hole 34. In the second region, it is considered that a part of the depolymerization also occurs, but it is considered that most of the polymerization reaction due to the chain extender occurs.

In the third region, since almost no polymerization reaction due to the chain extender occurs, acetaldehyde does not reoccur, and the molten PET resin is extruded without leaving acetaldehyde.

As described above, since it can be modified to a high molecular weight of 3 dimensions by a polymerization reaction, not only PET resins used in ordinary bottles or containers, but also PET resins or recycled PET sheets which are inexpensive, can be modified. Usefully utilized.

The extruder 40 is also provided with a cylinder 41, a screw shaft 42, a first vent hole 43, a second vent hole 44, a pressurizing and compressing portion (not shown), and a sealing portion (in the same manner as the main ejector 30). Not shown in the figure, the PET resin to be charged also removes water in substantially the same process.

The outlets 37 and 45 of the main extruder 30 and the sub-extruder 40 are connected to the T-die 60 through the feeding block 50, and the PET resin supplied from the main extruder 30 is supplied by the T-die 60. The virgin PET resin supplied from the sub-extruder 40 is formed by co-extruding the laminated sheet a formed of the main layer and the inner layer. Further, at this time, the printing film b is fed out by the printing film conveying roller 80, and the cooling film 70 is superposed on the main layer of the laminated sheet a, and is thermally bonded as an outer layer. Connect The laminated sheet c formed of the inner layer, the main layer, and the outer layer is wound around the winding roller 90.

Next, when the laminated sheet formed as described above is molded into a container, as shown in FIG. 3, after the laminated sheet c is heated by the heater 100, it is molded into a container by a thermoforming machine shown in FIG. In FIG. 4, 111 is a master mold, 112 is a male mold, and heaters 113 are embedded in the master mold 111 and the male mold 112. Further, a plurality of vacuum ports (not shown) are formed in the master mold 111, and a plurality of vacuum/pressure air ports (not shown) are formed in the male mold 112.

When the heat-resistant transparent container is produced by the thermoforming machine as described above, the laminated sheet c is introduced into the thermoforming machine, and the vacuum/pressure air port of the male mold 112 is sucked to adsorb the laminated sheet c to the male mold 112 to form Container shape. After being temporarily held in this state and thermally fixed, the pressurized air is blown from the vacuum/pressure air port to press the container against the master mold 111, and the outside of the container is cooled.

Example 1 [Modulation of PET resin material]

83 parts by weight of PET resin ("MA-2101M" manufactured by Unitika Co., Ltd.: intrinsic viscosity: 0.62 dl/g, water content: 2,900 ppm), talc MB ("PEX1470" manufactured by Tokyo Ink Co., Ltd.: L PDE 30% by weight + talc) 70% by weight, 10 parts by weight, chain extender MB (Ming Cai Chemical Co., Ltd.: PETG 70% by weight + ADR4368S 30% by weight of BASF Japan) 1 part by weight, White pigment MB ("L-9583" manufactured by Dainippon Ink Co., Ltd.: 50% by weight of PET + 50% by weight of white pigment) 4 parts by weight, and 2 parts by weight of phase solvent ("LOTADER AX8840" manufactured by Arkema Co., Ltd.), using a weight type Quantitative feeders, each metered and uniformly mixed in a mixer.

[Production of laminated sheets]

The PET resin material (for the main layer) was placed in a main extruder ("TEX105 α" manufactured by Nippon Steel Works Co., Ltd.:) / D = 31.5, 2 axes, 2 vent holes), and the extrusion temperature was 280 ° C. The vent hole was pushed out while being degassed under a high vacuum of -101 kPa, and PET resin (inner layer: "MA-2101M" manufactured by Unitika Co., Ltd.: intrinsic viscosity: 0.62 dl/g, moisture: 2,900 ppm) was put in. To the sub-extrusion machine ("TEX65 α" manufactured by Nippon Steel Works Co., Ltd.: L/D = 31.5, 2-axis, 2 vent holes), and the venting temperature is 280 ° C, and the two vent holes are operated under a high vacuum of -101 kPa. The suction and degassing are carried out, and a laminated sheet formed of the main layer and the inner layer is formed by a T-die.

In addition, at the same time, the A-PET film having a thickness of 30 μm is printed with the printed pattern of the processed milk roast and the printed film (outer layer) of the text, and the co-extruded resin layer from the T-die is attached. On the outer side of the main layer of the layer/inner layer, lamination was carried out by thermal bonding, and a laminate sheet having an outer layer (30 μm)/main layer (300 μm)/inner layer (30 μm) and a total thickness of 360 μm was produced.

<Action of water>

The screw shaft and the vacuum suction in the continuous extrusion were temporarily stopped, and the resin at the positions of the first and second vent holes of the main extruder and the sub-extruder was sampled, and the moisture content was measured. The moisture measurement system uses a water vaporization device for plastics ("ADP-351" manufactured by Kyoto Electronics Co., Ltd.) and a Karl Fischer moisture meter (MKC-210 manufactured by Kyoto Electronics Co., Ltd.). "). The results are shown in Table 1.

Regardless of the resin of the main extruder or the resin of the sub-extruder, the amount of water contained in the first vent hole before the input is 10 μm or less, and 50 ppm or less required for the general PET resin to be extruded. The position of the second vent hole was 0 ppm, and it was found that suction and degassing were performed by the vent hole, and thus it was not necessary to perform drying beforehand.

<Evaluation of residual acetaldehyde>

The laminated sheet was cut into a size of 1 cm × 2 cm to prepare a cutting piece for a food tray, and then a plurality of cutting pieces having a surface area equivalent to a total surface area of 250 m ² were placed in a 500 ml ground stopper. Glass conical flask. Next, the air in the Erlenmeyer flask (N ₂ gas 2 ml / surface area 1 cm ² ) was replaced with N ₂ gas at 40 ° C in a chamber at 40 ° C, and then sealed with a stopper and left at 40 ° C for 24 hours.

The acetaldehyde in the gas phase of the Erlenmeyer flask treated as described above was measured by a gas chromatograph ("GC-6A type" FID detector manufactured by Shimadzu Corporation). The results are shown in Table 2.

No acetaldehyde was detected by gas chromatography. Therefore, it was confirmed that acetaldehyde did not remain.

[Formation of heat-resistant food containers]

A vacuum/pressure air forming machine ("FVS-5000P" manufactured by Wakisaka Engineering Co., Ltd.) was used to form a molding die in a similar shape so that the die spacing between the master die and the male die was 1.0 mm. Both of the male molds form a vacuum/pressure air port of 0.7 mm, and the vacuum and the pressurized air are switched to perform suction and pressure air blowing. The shape of the mold is formed as a master mold to have an upper diameter of 128 mm. Lower diameter 95mm The depth is 35 mm, and the lower corner 隅 is formed to take a circular R shape.

The laminated sheet produced as described above was heated and softened so that the surface temperature became 130 ° C by the heater, and then the master mold was set to 170 ° C and the male mold was set to 70 ° C. In this state, the vacuum/pressure air port of the master mold is formed into a vacuum, and the vacuum/pressure air port of the male mold is formed as The pressurized air was blown into the pressure air of 0.5 MPa, and the laminated sheet and the master mold were adhered to each other to form a container in 5.0 seconds. Then, the vacuum/pressure air port of the master mold was formed into pressurized air and a pressure of 0.5 MPa was blown. Air, and the vacuum/pressure air port of the male mold was formed into a vacuum, and the container was cooled in close contact with the male mold for 5.0 seconds to take out the container. The molded product is excellent in mold release from the mold, and there is no wrinkles or deformation, and the shape of the mold is completely reproduced. In addition, the appearance does not have the fading or discoloration of the printing ink, and is an appearance excellent in appearance.

<The degree of crystallization of the molded article>

A part of the bottom of the molded article was cut out, and 10.0 mg of the molded product was used as a sample, and each heat amount was determined by a differential scanning calorimeter (Seico Electronics "DSC220"), and the calculation was performed according to the following formula. The measurement conditions were measured by circulating nitrogen at a concentration of 10 ml/min on a measurement sample (10.0 mg) while raising the temperature to 20 to 300 °C.

The degree of crystallization was 21.9%.

<solid content contributing to heat resistance>

As described above, in the soft sea of the amorphous portion of PET, the total amount of the crystalline portion of PET as a solid and talc contributes to heat resistance, and The amount present will affect the heat resistance.

Therefore, the solid content = the degree of crystallization of PET + talc content = 21.9 + 7 = 28.9%

The degree of crystallization of PET is the total amount of the molded article, and the talc content is only the content of the main layer. However, the heat resistance of the main layer is mainly contributed to the heat resistance, and it can be judged by the total amount. Heat resistance.

<The heat resistance of the molded article>

The molded product was placed in a constant temperature drier at 200 ° C for 20 minutes. After observing the appearance, there were no wrinkles or wrinkles, and no deformation, and the shape before the test was maintained. As a result of measuring the degree of crystallization by DSC, 21.9% before the test became 25.8% after the test, and it was considered that the crystallization progressed, and the measurement was caused by the time of 0 minutes, 10 minutes, 20 minutes, and 30 minutes at 200 ° C. Degree of crystallization. The results are shown in Table 3.

The crystallization progresses with the passage of time, and the heat resistance is improved.

<heat conditioning>

The commercially available frozen milk sauce was placed in a shaped container and heated in an oven at 250 ° C for 15 minutes. The milk-baked vegetables were well conditioned, the contents were taken out, and the appearance of the container after the washing was observed, and the appearance of the inner PET resin layer was observed, but there was no deformation such as wrinkles or twists, and the inner PET resin layer did not have any Variety.

After the contents were taken out and washed, the degree of crystallization of the container was measured by DSC to be 25.3% (degree of crystallization + amount of talc = 32.3%). When heated at 250 ° C, the container does not rise to this temperature due to contact with the contents, and the crystallization progresses in the time elapsed from 100 ° C to 220 ° C of the optimum crystallization temperature shown in FIG. 5 .

Example 2 [Production of laminated sheets]

For the main extruder, 84 parts by weight of PET resin ("MA-2101M" manufactured by Unitika Co., Ltd.) and 1 part by weight of chain extender MB (Ming Cai Chemical Co., Ltd.) and talc MB (Tokyo) were used. 10 parts by weight of ink (PEX1470), phase solvent (2 parts by weight of "LOTADER AX8840" manufactured by Arkema Co., Ltd., black pigment MB (Big-Japan ink (share)" "BK-250DCT": PET 70% + black pigment 30% 3 parts by weight of the PET resin material, in addition to the use of PET resin (Unitika) In the same manner as in Example 1, except for "MA-2101M", a laminate sheet having a total thickness of 300 μm in the main layer (300 μm)/inner layer (30 μm) was produced. Among them, the printed film is not attached.

[Formation of heat-resistant food containers]

Using a vacuum/pressure air forming machine and a mold which were completely the same as in Example 1, the male mold was used as a heating mold, and the master mold was used as a cooling mold. That is, after the laminated sheet was heated and softened so that the surface temperature became 130 ° C, the vacuum/pressure air port of the male mold set to 170 ° C was formed into a vacuum, and the master mold set to 70 ° C was set. The vacuum/pressure air port is formed into pressurized air and blows 0.5 MPa of pressurized air, and the laminated sheet is adhered to the male mold in 5.0 seconds to form a container, and then the vacuum/pressure air port of the master mold is formed into a vacuum, and The vacuum/pressure air port of the male mold was formed into pressurized air, and 0.5 MPa of pressurized air was blown, and the container was cooled in close contact with the mother mold, and the container was taken out. The molded product is preferably released from the mold, and is free from wrinkles, deformation, and completely reproduces the shape of the mold.

<The degree of crystallization of the molded article>

In the same manner as in Example 1, a part of the bottom portion was cut out, and the degree of crystallization was measured by DSC. The result was 23.0%. With the content of talc of 7%, it becomes: [Number 4] Crystallinity (%) of PET + talc amount (%) = 30.0% , has sufficient heat resistance.

(industrial availability)

Since the food container of the present invention is subjected to a conditioning temperature of 180 to 250 ° C, a food container or the like in the case of being heated and conditioned can be widely used.

31‧‧‧ cylinder

32‧‧‧Spiral axis

33, 34‧‧‧ vents

35‧‧‧Pressure compression department

36‧‧‧ Sealing Department

Claims (3)

A heat-resistant food container characterized in that a chain extender, a phase solvent, and talc of 3 to 10% by weight based on the PET resin are added to a PET resin serving as a main layer, and the main extruder is placed in a vent hole of 2 or more. And the PET resin which is an inner layer is put into the sub-extrusion machine with a vent hole of 1 or more, and the vent hole is pumped by the high vacuum of -99.99 kPa or more in the state which heat-melted each PET resin. After the gas is formed, the sheet formed by the main layer and the inner layer is formed by a co-extrusion method, and the sheet is formed into a vacuum/pressure air by a thermoforming machine, and is kept at 100 to 220 ° C in the forming mold to form a container. The thickness of the layer is 25 μm to 50 μm, and the thickness of the main layer + the inner layer is 2.5 to 10%, and the total amount of the crystalline portion and the content of the talc shown in the following formula of the container is 25 to 40% by weight, the chain The extender is one having three or more epoxy groups, and the phase solvent is an ethylene/acrylic acid/glycidyl methacrylate copolymer. The heat-resistant food container according to claim 1, wherein the printing is performed by heat-bonding, and the printing is performed by an A-PET film or a film in which the A-PET film is extended 1.5 to 2.5 times in the MD direction. The film is formed into an outer layer. A method for manufacturing a heat-resistant food container, characterized in that: A chain extender having three or more epoxy groups, a phase solvent of an ethylene/acrylic acid/glycidyl methacrylate copolymer, and talc 3 to 10% by weight are added to the PET resin to be the main layer, and the vent hole is added to the vent hole. 2 or more of the main extruders, and the PET resin which is an inner layer is put into a sub-extrusion machine having a vent hole of 1 or more, and the vent hole is high at -99.99 kPa or more in a state where the respective PET resins are heated and melted. After suction and degassing under vacuum, the main layer and the inner layer are formed by a co-extrusion method, and the main layer is subjected to an A-PET film or a film in which the A-PET film is extended 1.5 to 2.5 times in the MD direction. The outer layer of the gravure printed film is laminated by thermal bonding, and the laminated sheet formed of the inner layer, the main layer and the outer layer is formed into a vacuum/pressure air by a thermoforming machine, and is maintained at 100 in the forming mold. The thickness of the inner layer obtained at ~220 ° C is 25 μm to 50 μm, which is 2.5 to 10% of the thickness of the main layer + inner layer.