KR102473886B1 - Eco-friendly foaming multi-layer sheet, ice pack using same, and manufacturing method thereof - Google Patents

Abstract

The present invention relates to an eco-friendly foam multi-layer sheet, an ice pack using the same, and a manufacturing method thereof. More specifically, the present invention relates to a non-stretched polyethylene foam multi-layer sheet including a top layer sheet (110) and an inner layer sheet (120), wherein the top layer sheet is in a form in which outer layer A (111) and inner layer A (112) are stacked, and the inner layer sheet is in a stacked form in which a foam layer (121) and inner layer B (122) are thermally laminated, an ice pack using the same and a manufacturing method thereof.

Description

Eco-friendly foaming multi-layer sheet, ice pack using the same, and manufacturing method thereof {Eco-friendly foaming multi-layer sheet, ice pack using same, and manufacturing method thereof}

The present invention relates to an eco-friendly foam multilayer sheet, an ice pack using the same, and a manufacturing method thereof. More specifically, in an unstretched polyethylene foam multilayer sheet composed of a top layer sheet 110 and an inner layer sheet 120, the top layer sheet has an outer layer A 111 and an inner layer A 112 laminated, and the inner layer sheet The layer sheet is characterized in that the foam layer 121 and the inner layer B 122 are thermally laminated in a laminated form, and relates to an ice pack using the same and a manufacturing method thereof.

Recently, as the transportation industry has become more active due to the influence of Corona 19, the demand for food that requires fast delivery has increased. Moreover, as sales in the online food market increased, competition among the distribution industries that deliver fresh food early in the morning has intensified.

Food can spoil quickly, so it must be stored at low temperatures to maintain freshness. In general, dry ice or ice packs are used as a means of freezing or refrigerating storage during transportation.

An ice pack can be used by mixing a refrigerant with a high specific heat and water and then freezing it to keep the surroundings at a low temperature through the heat absorbing action of the ice pack. Unlike the dry ice, such an ice pack is widely used because it is easy to handle and store.

Existing ice packs are mostly composed of petrochemical products, and materials such as nylon/polyethylene or non-woven fabric (PP, PE)/polyethylene are mainly used.

In the case of the nylon/polyethylene material, since it is composed of two or more types of multi-materials in which a stretched nylon film with excellent impact resistance and toughness and a polyethylene film with excellent bag formability are laminated, it is impossible to recycle, so the entire amount is incinerated or landfilled. It is inevitable, and this causes serious environmental pollution.

In addition, in the case of polyethylene/polyethylene material, since both the outer and inner layers are polyethylene, it is excellent in terms of recycling, but in order to maintain impact resistance and toughness, the outer layer of the sheet is uniaxially or biaxially stretched It was necessary to laminate using a polyethylene stretched film (see Patent Documents 1 and 2). Polyethylene stretched film processing is only possible with specific machines, so the equipment investment cost is excessive and the production cost is very high. In addition, it is difficult to manufacture a uniform stretched film because physical properties vary greatly depending on equipment characteristics or stretching ratio.

Accordingly, ice packs made of paper have been developed, but considering the functions and effects of cold packs and their future reuse, they have not yet been actively applied. That is, the ice pack made of the above material has a problem in that the buffering effect against external shock is low and the durability against moisture is very weak (see Patent Document 3).

In addition, the inside of the ice pack is filled with a mixture of superabsorbent polymer with a gel-type crosslinked structure and water, and the frozen product is sometimes used as a refrigerant. It also causes serious water pollution.

As an alternative to this, an ice pack product using water filled in a plastic packaging and frozen ice as a refrigerant has recently been mainly used. However, when the packing material is damaged due to impact, since ice, which is a refrigerant, is broken into a sharp and pointed shape, many problems may occur, such as perforation due to ice fragments when falling. Therefore, packaging materials for ice packs using ice as a refrigerant require excellent impact resistance or drop breakage resistance.

Therefore, it is necessary to develop an eco-friendly multi-layer sheet with good low-temperature cold retention by ice, a packaging material with excellent impact resistance, drop breakage resistance, and bag moldability, and which can be recycled after use by a single material, and an ice pack using the same. do.

Domestic Patent Registration No. 10-2261130 (Registration date 2021.05.31.) Domestic Patent No. 10-2240271 (Registration date 2021.04.08.) Domestic Patent Publication No. 2021-0122924 (published date 2021.10.13.)

The present invention is to provide a multi-layer foam sheet for ice packs composed of only unstretched polyethylene film for the impact resistance and cold retention of a packaging material using ice as a refrigerant.

In addition, it is intended to provide an eco-friendly ice pack packaging material that is composed of only polyethylene single material and does not cause any problems in recycling after use.

The present invention is an unstretched polyethylene foam multi-layer sheet composed of a surface layer sheet 110 and an inner layer sheet 120, wherein the surface layer sheet has an outer layer A 111 and an inner layer A 112 laminated, and the inner layer The foam layer 121 and the inner layer B 122 are laminated and thermally laminated to provide a foam multilayer sheet for an ice pack packaging material.

The two laminated sheets 110 and 120 are characterized in that they are manufactured by a blown extruder.

For the outer layer A (111) of the surface layer sheet, a single high-density polyethylene resin having a density in the range of 0.950 to 0.970 g/cm3 is used, or a high-density polyethylene resin having a density in the range of 0.950 to 0.970 g/cm3 and a density of 0.920 to 0.920 g/cm3 is used. It is characterized in that other resins in the range of 0.940 g / cm3 are mixed within the weight ratio range of 20:80 to 99:1.

For the foam layer 121 of the inner layer sheet, low density polyethylene resin to which a foaming agent is added is used alone or 90 to 50 parts by weight of low density polyethylene resin is mixed with 10 to 50 parts by weight of linear low density polyethylene or vinyl acetate, Their melt index is characterized in that the range of 0.2 ~ 8 g / 10min.

The foaming agent is characterized in that any one selected from organic or inorganic thermal decomposition foaming agents, nitrogen, carbon dioxide, propane, and butane is used.

The inner layer sheet is composed of at least two or more multi-layer sheets including the foam layer 121, and if necessary, the outer layer B 123 is additionally laminated on the foam layer 121.

For the inner layer B 122 of the inner layer sheet, a resin having a heat-sealing temperature of less than 125° C. is selected, and a polyolefin elastomer having a density of 0.860 to 0.900 g/cm3, an ultra-low density polyethylene of 0.880 to 0.910 g/cm3, and a resin having a density of 0.915 to 0.925 It is characterized in that it is one or a mixture of two or more selected from the group consisting of g/cm3 of low-density polyethylene and 0.915 to 0.925 g/cm3 of linear low-density polyethylene.

The two laminated sheets are characterized in that they are laminated through dry lamination or T-die.

The surface layer sheet has a thickness of 20 to 60 μm and the inner layer sheet has a thickness of 60 to 170 μm.

Provided is an ice pack including the foam multilayer sheet for the ice pack packaging material.

A method for manufacturing a foamed multi-layer sheet for an ice pack packaging material according to the present invention includes the steps of: 1) preparing a surface layer sheet in which two or more layers are laminated with an outer layer A and an inner layer A in which a non-stretched high-density polyethylene resin is mixed; 2) preparing an inner layer sheet in which two or more layers of a foam layer mixed with an unstretched low density polyethylene resin and an inner layer B are laminated; and 3) laminating the two laminated sheets 110 and 120 through dry lamination or T-die.

The laminated sheets of steps 1) and 2) are characterized in that they are produced by a blown extruder.

An ice pack manufactured by the above manufacturing method is provided.

In the present invention, due to the use of the foamed multi-layer sheet including the foam layer 121, the ice pack packaging material showed excellent characteristics in both breakage resistance from falling and cooling effect.

In addition, since the material composition of the packaging material is a uni-material made entirely of polyethylene, there is no problem of changing the shrinkage rate during the multi-layer laminating process, and it can be usefully used as an eco-friendly ice pack with excellent recyclability after use.

In particular, since a non-stretching polyethylene resin is used, a special stretching device is not required, so there is an effect of reducing production costs in the process.

1 is an enlarged view of one cross section of a foam multilayer sheet according to an embodiment of the present invention.
2 is an enlarged view of one cross section of a foam multilayer sheet according to another embodiment of the present invention.

Hereinafter, the present invention will be described in more detail. However, the following examples are only one reference for explaining the present invention in detail, but the present invention is not limited thereto, and may be implemented in various different forms.

Conventional ice packs are manufactured by processing a film (or sheet) made of synthetic resin into a bag, injecting water into the bag, and sealing the film.

In general, polyethylene resins are inexpensive, have excellent mechanical properties, sanitary compatibility, water vapor permeability, and have good appearance of molded products, so they are widely used as various packaging materials or blown moldings. However, when used as a product by containing contents such as water or ice, it may be destroyed due to insufficient drop impact strength at low temperatures, so its improvement is required, so the material is changed or the structure is designed as a multi-layer sheet.

Even if the outer inner layer is a packaging material made of a single polyethylene material, in the case of using a polyethylene stretched film uniaxially or biaxially stretched for the outer layer for ultra-impact resistance, dry lamination with the inner unstretched polyethylene film During the process, the shrinkage rate of the film is greatly changed, and the film may be twisted or curled.

Accordingly, the present inventors selected unstretched polyethylene as the resin used in the multi-layer sheet, and manufactured a sheet in which two or more layers were laminated with a blown extruder for low-temperature impact resistance and used as a surface layer sheet, and a foam layer for a cooling effect. The present invention has been completed with a multi-layer sheet method including (121) as an inner layer sheet.

The eco-friendly ice pack 10 of the present invention is characterized in that it is composed of a non-stretched polyethylene foam multilayer sheet. 1 is an enlarged view of one cross section of a foam multilayer sheet according to an embodiment of the present invention. The layer structure of the foamed multi-layer sheet is composed of the surface layer sheet 110 and the inner layer sheet 120 of the ice pack.

The surface layer sheet 110 is a two-layer form (outer layer A + inner layer A) of high-density unstretched polyethylene having high thermal stability, and the inner layer sheet 120 is a foamed foam containing a low-density unstretched polyolefin-based elastomer capable of low-temperature heat-sealing. Layer 121 is introduced and laminated in two layers (foam layer + inner layer B).

The surface layer sheet and the inner layer sheet of the ice pack may be laminated by dry lamination separately or laminated with polyethylene molten material coming out through a T-die. At this time, it is important to manufacture the thickness of the surface layer sheet within the range of 20 to 60 μm, and in particular, 40 μm is most preferable. In addition, the thickness of the inner layer sheet is appropriately 60 to 170 μm, and particularly preferably 140 μm.

At this time, since both the multi-layer surface layer sheet and the inner layer sheet are characterized by using unstretched films, there is no need to undergo an additional film stretching process, and thus the present invention was manufactured through a blown film multi-layer extruder. In this method, after melting several different raw materials in an extruder, the melted raw materials are combined in a die to pull out several layers of films at the same time to make a multi-layer film (sheet).

Surface layer sheet (110)

The surface layer sheet of the ice pack is composed of outer layer A (111) and inner layer A, and since it is used as a non-stretched film instead of a polyethylene stretched film that requires stretching equipment, the processing method is simplified, and the coextrusion method for producing a blown film is used. layered using it. That is, it can be manufactured in a general commercial LDPE or LLDPE blown extruder.

High-density polyethylene with high thermal stability was selected as the resin used as the non-stretched film, so that the film was not twisted or melted during heat-sealing so that high-speed sealing (adhesion) could be performed during heat-sealing.

In addition, in order to increase low-temperature impact resistance, a multilayer (two to five layer) film is preferred rather than a single-layer film.

The unstretched polyethylene resin used in the outer layer A (111) has a density in the range of 0.950 to 0.970 g/cm3 alone, or a high-density polyethylene resin with a density in the range of 0.950 to 0.970 g/cm3 with a density of 0.920 to 0.940. It can be used by mixing in the range of g / cm3 at a certain content ratio. Preferably, the mixing weight ratio of the two resins may be selected within the range of 20:80 to 99:1.

Meanwhile, when polyethylene having a density within the above range is used, heat resistance is sufficiently improved, but low-temperature impact resistance may not be so high. Therefore, a two- to three-layer film is preferable rather than a single layer. For example, in the case of a three-layer film, the outer layer A (111) is polyethylene having a density of 0.950 to 0.970 g / cm3, the middle layer is polyethylene with a density of 0.950 to 0.970 g / cm3, and the inner layer is When polyethylene having a density of 0.950 g/cm 3 or less is mixed with A (112), the low-temperature impact resistance can be further improved.

Inner layer sheet (120)

The inner layer sheet of the ice pack is composed of a foam layer 121 and an inner layer B 122, all of which are characterized by a polyethylene non-stretched foam film, and the main purpose is to improve the cooling effect and heat sealability of ice.

For the above characteristics, it is composed of a multi-layer sheet of at least two layers. If necessary, a three-layer sheet can be manufactured, which laminates the outer layer B 123 on the foam layer 121 as shown in FIG. 2 (see Examples 2 and 4). 2 is an enlarged view of one cross section of a foam multilayer sheet according to another embodiment of the present invention.

First, the foam layer 121 of the inner layer sheet is made with a blown film extruder using a low-density polyethylene resin to which a foaming agent is added. you need to consider In general, when a foaming process is performed, empty spaces are generated due to foamed cells and their distribution has a great effect on mechanical strength, so flowability among physical properties of the resin needs to be considered as a major factor. Therefore, the melt index (MI) of the resin used is preferably in the range of 0.2 to 8 g/10 min.

The resin used is preferably low-density polyethylene alone, but if necessary, 10-50 parts by weight of linear low-density polyethylene or ethylene vinyl acetate may be mixed with 90-50 parts by weight of low-density polyethylene resin.

In order to improve blow moldability, heat stabilizers, weathering stabilizers, ultraviolet absorbers, radiation resistance agents, crystal nucleating agents, inorganic fillers, lubricants, plasticizers, organic peroxides, neutralizers, crosslinking agents, pigments, Various additives such as dyes and additives such as elastomers to improve mechanical properties may be added.

The foaming rate of the foam layer 121 has a ratio of 20% to 200%, and the foaming rate can be adjusted using an inorganic or organic foaming agent or gas foaming agent. Examples of specific foaming agents include organic or inorganic thermal decomposition foaming agents, gases such as nitrogen, carbon dioxide, propane, and butane. The foaming agent may be added to the resin used as it is, but it may be added as a master batch added to the resin component in advance to improve dispersibility.

As a foaming aid, talc, silica, titanium oxide, stearic acid, phthalic acid, zinc stearate, lead stearate, magnesium stearate, calcium stearate, ethylene glycol, glycerin, ethanolamine, urea, urea derivatives, melamine, lead 2 alkali phosphite, lead 3 alkali sulphate , zinc oxide, etc. can be compounded.

In particular, in order to manufacture a multi-layer sheet including the foam layer 121, the above component ratios as well as manufacturing conditions are very important, but are not particularly limited here.

In addition, it is necessary to manufacture the inner layer sheet by blow-extruding the inner layer B 122 together with the foam layer 121. The foam layer 121 serves for an excellent cooling effect, but because of this, there is some difficulty in filling a refrigerant such as ice and bonding it into a bag, so the inner layer B 122 was laminated together as a way to compensate for this. . At this time, it is preferable that the heat-sealing temperature of the resin used for the inner layer B 122 is less than 125°C. Preferably, it is best to select a resin that is 90 to 100 ° C.

Polyethylene resins for the above properties include polyolefin elastomers with densities of 0.860 to 0.900 g/cm3, ultra-low density polyethylene with 0.880 to 0.910 g/cm3, low density polyethylene with 0.915 to 0.925 g/cm3, and linear 0.915 to 0.925 g/cm3. It may be one or a mixture of two or more selected from the group consisting of low-density polyethylene.

The reason why such a resin is additionally laminated and used is that the low-temperature impact resistance of the packaging material is improved and at the same time, when a refrigerant such as ice is packaged and sealed, it is possible to seal at a relatively low temperature and at a high speed.

Hereinafter, the present invention will be described focusing on the following Examples and Comparative Examples.

[Example 1]

The surface layer sheet of the ice pack was a polyethylene unstretched film and a two-layer blown extruder was used. In the surface layer sheet, the resin of the outer layer A (111) is Hanwha Total's C440A (MI: 2.1, density: 0.968 g / cm3) and Lotte's UL912A (MI: 1.2, density: 0.920 g / cm3) 50: 50 content, respectively The resin of inner layer A was mixed with C440A of Hanwha Total and UL912A of Lotte in a content (weight) ratio of 20:80, respectively. At this time, the total thickness of the surface layer sheet was set to 40 μm.

The inner layer sheet of the ice pack was a polyethylene non-stretched foam film using a two-layer blown extruder. The resin used for the foam layer 121 of the inner layer sheet was Hanwha Solutions' LDPE 5302 (MI: 0.3, density 0.922 g/cm3), and the foaming agent was a mixture of sodium bicarbonate and azodicarbonamide at a ratio of 1:1. A 30% concentrated masterbatch was prepared in advance with Hanwha Solutions' LDPE 5321, and then mixed with 3% of the foam layer 121. At this time, the thickness of the non-stretched foam layer 121 was 100 μm before foaming, but was adjusted to 140 μm after foaming. In particular, since the inner layer B (122) of the inner layer sheet must be heat-sealable at a relatively low temperature, SK's Supreme 891 (MI: 1.0, density 0.885 g/cm3) and Hanwha Solutions' 4200D (MI: 1.6, density 0.920 g/cm3) were used. cm3) was used in a 50:50 content ratio.

A multi-layer sheet was prepared by T-die coating and laminating the unstretched films of the two sheets prepared, that is, the ice pack surface layer sheet and the inner layer sheet. The resin used for T-die coating was laminated while extruding under conditions of 160 to 180 ° C using Hanwha Solutions' LDPE 950 (MI: 7.5, density 0.919 g / cm3).

The drop breakage resistance and cooling effect of the ice pack manufactured by sealing with the foamed multilayer sheet were measured, and the results are shown in Table 3.

[Example 2]

For the inner layer sheet of the ice pack, the polyethylene non-stretched foam film was gas-blown using a three-layer blown extruder (see FIG. 2). The foam layer 121 of the inner layer sheet was located in the middle layer, and the gas blowing agent used was nitrogen. The outer layer B (123) of the three-layer inner layer sheet was the same as in Example 1 except that Hanwha Solutions' LLDPE 4200D (MI: 1.6, density 0.920 g/cm3) was used.

[Example 3]

In the surface layer sheet of the ice pack, the resin of the outer layer A (111) was Hanwha Total's F920A (MI: 1.0, density: 0.954g/cm3) and Lotte's UL912A (MI: 1.2, density: 0.920g/cm3) at a ratio of 60: 40, respectively. The mixture was used in a weight ratio. The resin of the inner layer A was the same as in Example 1 except that Hanwha Total Petrochemical's F920A and Lotte's UL912A were mixed at a weight ratio of 30:70.

[Example 4]

The surface layer sheet of the ice pack was prepared in the same manner as in Example 3, and the inner layer sheet was prepared in the same manner as in Example 2. Other than that, it was the same as in Example 1.

[Comparative Example 1]

The surface layer sheet of the ice pack was a polyethylene unstretched film and used a two-layer blown extruder. The outer layer A (111) resin was a mixture of Hanwha Total Petrochemical's F920A (MI: 1.0, density: 0.954 g/cm3) and Lotte's UL912A (MI: 1.2, density: 0.920 g/cm3) at a weight ratio of 20:80, respectively. For the inner layer A resin, 100% of Lotte's UL912A was used alone. The thickness of the film was 40 µm.

Unlike Example 1, the inner layer sheet of the ice pack did not use the foam layer 121, but used a general polyethylene unstretched film. That is, Hanwha Solutions' 4200D (MI: 1.6, density 0.920g/cm3) as the non-foamed outer layer B (123) resin and LG SP311 (MI: 1.0, density 0.918g/cm3) as metallocene LLDPE at a 50:50 content ratio. The mixture was mixed in a ratio, and the same resin as in Example 1 was used as the inner layer B (122) resin.

The two sheets manufactured, that is, the unstretched film of the ice pack surface layer sheet and the inner layer sheet, were laminated by T-die coating in the same manner as in Example 1, and then the physical properties were measured in the same manner as in Example 1, and the results are shown in the table 3.

[Comparative Example 2]

A product currently on the market as an ice pack packaging film (sheet) was selected as Comparative Example 2. It is not clear how it was manufactured, but it was visually confirmed that it was not a packaging material including the foam layer 121. After obtaining an ice pack made of a single PE material used by “Coupang,” a delivery company, and leaving the ice pack at room temperature for a long time to completely melt the water, the breakage resistance and cooling effect were measured in the same way as in Example 1, and the results is shown in Table 3.

Evaluation 1. Drop breakage resistance

Drop breakage resistance can simultaneously exhibit low-temperature impact resistance and puncture resistance. The surface layer sheet and the inner layer sheet of the ice pack are dry laminated and laminated, and then an envelope having a size of 150 mm in width and 200 mm in length is made, filled with 300 g of water, heat-sealed, and sufficiently frozen to prepare an ice pack sample. Thereafter, the free fall from a height of 2 m was measured for damage rate in 4 grades. Ten samples were prepared and dropped to measure the average breakage rate.

2m drop Great Good usually error Breakage rate (%) less than 10% less than 20% 20% to 50% more than 50%

Evaluation 2. Cooling effect

For the cold insulation effect, make an ice pack in the same way as when evaluating drop breakage resistance, fill it with 300 g of water, and heat-seal it. When the water was sufficiently frozen, the ice pack was left indoors at room temperature of 25° C. for 2 hours and 4 hours, and then opened and the weight of water produced was measured and compared.

cold storage Great Good usually error Amount of water dissolved after 2 hours 50 g or less 70 g or less 100g or less 100g or more Amount of water dissolved after 4 hours 140g or less 170g or less 200g or less 200g or more

Based on the above evaluation method, when comparing Examples 1 to 4 and Comparative Examples 1 to 2, it can be seen that there is a significant difference in drop breakage resistance and cooling effect.

First, it was confirmed that the cooling effect varied depending on the presence or absence of the foam layer 121 . That is, Examples 1 to 4 all include a foam layer on the inner layer sheet, and Comparative Examples 1 and 2 do not have a foam layer, so when comparing the two, there is a significant difference, especially when the amount of water dissolved after 4 hours is measured. show that there is For reference, Examples 2 and 4 include an additional outer layer B 123 other than the foam layer 121, and it was confirmed that they are somewhat superior to Examples 1 and 3 without the additional outer layer B 123.

In addition, even in the results of drop breakage resistance, which can be compared with impact resistance, the case of using a mixture of high-density non-stretched polyethylene resin in a specific ratio in which two layers are laminated shows relatively excellent results. In Comparative Example 1, the resin of the outer layer A (111) of the surface layer sheet is mixed at a content ratio of 20:80, and Examples 1 and 2 mixed at a content ratio of 50:50 or Example 3 mixed at a content ratio of 60:40, Compared to case 4, it can be seen that the breakage rate is about 20% to 30% higher.

test drop breakage resistance Cooling effect Breakage rate (%) result Amount of water dissolved after 2 hours Amount of water dissolved after 4 hours result Example 1 0 Great 40 130 Great Example 2 0 Great 35 100 Great Example 3 10% Great 45 140 Great Example 4 0 Great 35 110 Great Comparative Example 1 30% usually 65 210 error Comparative Example 2 20% Good 60 180 usually

The foamed multi-layer sheet of the present invention is a combination of the surface layer sheet 110 and the inner layer sheet 120, and even if unstretched polyethylene is used, high-density resin is laminated on the outer layer A to improve low-temperature impact resistance (drop breakage resistance). In addition, since it shows an excellent cooling effect due to the introduction of the foam layer 121, it is very suitable for use as a packaging material such as an ice pack.

10 : ice pack
110: surface layer sheet, 111: outer layer A, 112: inner layer A
120: inner layer sheet, 121: foam layer, 122: inner layer B, 123: outer layer B

Claims (13)

In the non-stretched polyethylene foam multilayer sheet composed of the surface layer sheet 110 and the inner layer sheet 120,
The surface layer sheet is a laminated form of an outer layer A (111) and an inner layer A (112), and the inner layer sheet is thermally laminated in a laminated form with a foam layer (121) and an inner layer B (122),
For the outer layer A (111) of the surface layer sheet, a single high-density polyethylene resin having a density in the range of 0.950 to 0.970 g/cm3 is used, or a high-density polyethylene resin having a density in the range of 0.950 to 0.970 g/cm3 and a density of 0.920 to 0.920 g/cm3 is used. It is characterized by mixing other resins in the range of 0.940 g / cm3 within the weight ratio range of 20:80 to 99:1,
The inner layer A (112) of the surface layer sheet uses polyethylene having a density of 0.950 g/cm3 or less,
For the foam layer 121 of the inner layer sheet, low density polyethylene resin with a foaming agent added alone is used, or 90 to 50 parts by weight of low density polyethylene resin is mixed with 10 to 50 parts by weight of linear low density polyethylene or vinyl acetate, Their melt index is characterized in that the range of 0.2 ~ 8 g / 10min,
For the inner layer B 122 of the inner layer sheet, a resin having a heat-sealing temperature of less than 125°C is selected, and a polyolefin elastomer having a density of 0.860 to 0.900 g/cm3, an ultra-low density polyethylene of 0.880 to 0.910 g/cm3, and a resin having a density of 0.915 to 0.925 Characterized in that it is one or a mixture of two or more selected from the group consisting of g/cm3 low-density polyethylene and 0.915 to 0.925 g/cm3 linear low-density polyethylene.
Foam multilayer sheet for ice pack packaging The method according to claim 1, wherein the two laminated sheets (110, 120) are manufactured by a blown extruder, characterized in that the foam multi-layer sheet for ice pack packaging delete delete The method according to claim 1, wherein the foaming agent is one selected from organic or inorganic thermal decomposition type foaming agents, nitrogen, carbon dioxide, propane, and butane. The method according to claim 1, wherein the inner layer sheet is composed of at least two or more multi-layer sheets including the foam layer 121, and if necessary, the outer layer B 123 is additionally laminated on the foam layer 121. Foamed multilayer sheet for ice pack packaging delete The method according to claim 1, wherein the two laminated sheets (110, 120) are laminated through dry lamination or T-die. The method according to claim 1, wherein the surface layer sheet has a thickness of 20 to 60 μm and the inner layer sheet has a thickness of 60 to 170 μm. An ice pack comprising the foamed multilayer sheet for an ice pack packaging material according to any one of claims 1, 2, 5, 8, or 9 1) manufacturing a surface layer sheet 110 in which two or more layers are laminated with an outer layer A (111) and an inner layer A (112) mixed with unstretched high-density polyethylene resin;
2) manufacturing an inner layer sheet in which two or more layers of a foam layer 121 mixed with an unstretched low density polyethylene resin and an inner layer B 122 are laminated; and
3) a step of laminating the two laminated sheets (110, 120) through dry lamination or T-die; The method of manufacturing a foamed multilayer sheet for ice pack packaging according to claim 11, wherein the laminated sheets in steps 1) and 2) are manufactured with a blown extruder. delete

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