KR102261130B1 - Polyethylene Multi-film for super-impact resistant eco-friendly packaing of ice packs and ice packs containing the same - Google Patents

Abstract

The present invention relates to a polyethylene multi-layer film for a super-impact resistant eco-friendly ice pack packaging material using ice filled with water and frozen in the packaging material as a refrigerant, and an ice pack including the same. The ice pack has excellent low-temperature retention by ice, which is a refrigerant, and excellent impact resistance, low-temperature impact resistance, puncture resistance properties, drop breakage resistance, toughness and bag formability of packaging materials. At the same time, the ice pack has excellent recyclability after use by a uni material and at the same time and can be usefully used as an eco-friendly ice pack that is oxidized and biodegraded if it is buried in a landfill.

Description

Polyethylene Multi-film for super-impact resistant eco-friendly packaing of ice packs and ice packs containing the same}

The present invention relates to a polyethylene multilayer film for ultra-impact resistant eco-friendly ice pack packaging material and an ice pack comprising the same. More specifically, it has excellent low-temperature retention by ice, which is a refrigerant, excellent impact resistance, puncture resistance, toughness and bag formability of packaging materials, and excellent recyclability after use by Uni-Materials. It relates to a polyethylene multi-layer film for packaging materials that are oxidative and biodegradable when buried in a landfill, and an ice pack containing the same.

Recently, the online shopping market is rapidly increasing instead of the offline shopping market due to excellent convenience and the impact of COVID-19. As a result of the rapid growth of the fresh food delivery market, the use of essential ice packs is increasing rapidly. In the case of Korea, consumption of about 300 million units is expected this year.

The most widely used ice pack is a product that uses a mixture of water and a superabsorbent polymer having a gel-like cross-linked structure in a plastic packaging material and used as a refrigerant. During the disposal process, the molten gel-type refrigerant is simply thrown away, clogging the drain. It causes serious water pollution. In addition, in the case of plastic packaging materials for ice packs, since they are made of two or more multi-materials, they cannot be recycled, so the entire amount must be incinerated or landfilled, which causes serious environmental pollution. Recognizing the seriousness of the situation, the government is implementing strong regulations such as a significant increase in waste charges.

As an alternative to this, an ice pack product, which is filled with water in plastic packaging and frozen, that is, using ice as a refrigerant, has been launched. However, in the case of ice pack products in which ice is used as a refrigerant, if an ice pack product accidentally falls from about 1.2 m, which is the height of a consumer's shoulder, or about 2 m, which is a height of about 2 m when unloading a car, the ice pack in the box will be impacted and the plastic packaging material will be damaged. . In addition, many problems may occur, such as when the refrigerant ice is broken into a sharp and pointed shape, and the ice cubes pierce the packaging material and cause perforation. Therefore, the packaging material for ice packs using ice as a refrigerant is strongly required to have excellent impact resistance and puncture resistance.

In order to meet these requirements, a packaging material made of a composite film in which a stretched nylon film having excellent impact resistance, puncture resistance and toughness is laminated with a polyethylene film having excellent bag formability is widely used. Since ice is a refrigerant, this product becomes water after use and can be easily disposed of. Compared to a product that uses a frozen mixture of water and a superabsorbent polymer having a gel-type cross-linked structure as a refrigerant, the eco-friendliness is clearly improved. can be said to have been However, the plastic packaging material used is not a recyclable uni-material, but a multi-material composite film in which a stretched nylon film and a polyethylene film are laminated, so recycling is impossible. Therefore, plastic packaging materials are not biodegradable after being completely incinerated or disposed of in landfills, causing serious environmental pollution. A solution to these problems is urgent and urgent.

Therefore, during use, it has excellent low-temperature retention by ice, a refrigerant, and excellent impact resistance, puncture resistance, toughness and bag formability of packaging materials, excellent recyclability after use by uni material, and at the same time, it is oxidized if buried in landfill. There is an urgent need for the advent of biodegradable eco-friendly packaging materials for ice packs and ice packs containing the same.

In order to solve the above problems, the inventors of the present invention have come to the present invention as a result of repeated studies. That is, the present invention is to provide a polyethylene multilayer film for ultra-impact resistant eco-friendly ice pack packaging material that has excellent low-temperature retention by ice, which is a refrigerant, and has excellent impact resistance, puncture resistance, toughness and bag formability of the packaging material.

In addition, it is intended to provide a polyethylene multilayer film for eco-friendly ice pack packaging material that has excellent recyclability after use by uni-materials and is oxidatively biodegradable when buried in landfills.

The polyethylene multilayer film for ultra-impact-resistant eco-friendly ice pack packaging material of the present invention is characterized in that it comprises a uniaxially or biaxially stretched polyethylene film and a polyethylene unstretched film having an area stretch ratio of 2.0 or more.

The density of the stretched polyethylene film may be 0.920 g/cm 3 or more and 0.970 g/cm 3 or less.

The melting point of the polyethylene stretched film may be 115°C or more and 140°C or less.

The polyethylene multilayer film for the ultra-impact resistant eco-friendly ice pack packaging material may have the polyethylene stretched film as an outer layer and a polyethylene unstretched film as an inner layer.

The polyethylene unstretched film may be made of polyethylene alone or a mixture of polyethylene and polyethylene elastomer.

The polyethylene unstretched film may have a single-layer or multi-layer structure.

The polyethylene multilayer film for the eco-friendly ice pack packaging material may have a melting point (t1) of the stretched polyethylene film of the outer layer and a melting point (t2) of the polyethylene unstretched film of the inner layer satisfying the following formula (1).

Equation (1) t1 - t2 ≥ 10 °C

The polyethylene unstretched film melting point (t2) of the inner layer may be 60 ℃ or more and 125 ℃ or less.

The polyethylene used in the stretched polyethylene film and the polyethylene unstretched film may be any one or a mixture of two or more selected from the group consisting of ultra-low-density polyethylene, low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, and high-density polyethylene.

Any one or more selected from the polyethylene stretched film and the polyethylene unstretched film may further include an oxidative biodegradation accelerator.

The oxidative biodegradation accelerator may be a fatty acid metal salt, an acetyl-based organic metal salt, or a mixture thereof.

The method of manufacturing a polyethylene multilayer film for ultra-impact-resistant eco-friendly ice pack packaging material according to the present invention is

a) preparing a uniaxially or biaxially stretched polyethylene film having an area stretching ratio of 2.0 or more; and

b) preparing a polyethylene multilayer film by laminating, thermally laminating, cooling and winding a polyethylene melt melted in one or more extruders and coming out through a T-die on the stretched polyethylene film to be separately supplied;

It may be a method of manufacturing a polyethylene multilayer film for ultra-impact-resistant eco-friendly ice pack packaging material comprising a.

The present invention may provide an ice pack comprising the polyethylene multilayer film for the ultra-impact resistant eco-friendly ice pack packaging material.

The ice pack according to the present invention has excellent low temperature retention by ice, which is a refrigerant, and has excellent impact resistance, puncture resistance, toughness and bag formability of the packaging material.

In addition, the ice pack of the present invention is expected to be usefully used as an eco-friendly ice pack excellent in recyclability after use and oxidative biodegradability during landfill by uni-material.

Hereinafter, the present invention will be described in more detail. However, the following specific examples or examples are only a reference for describing the present invention in detail, and the present invention is not limited thereto, and may be implemented in various forms.

Also, unless defined otherwise, all technical and scientific terms have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description herein is for the purpose of effectively describing particular embodiments only and is not intended to limit the invention.

Also, the singular forms used in the specification and appended claims may also be intended to include the plural forms unless the context specifically dictates otherwise.

In addition, when a part "includes" a certain component, this means that other components may be further included rather than excluding other components unless otherwise stated.

In the present invention, the term “area stretch ratio” means the product of the lengthwise stretch ratio and the width direction stretch ratio.

In the present invention, “oxidative biodegradation” is a concept that includes decomposition of plastics due to complex actions such as heat, light, microorganisms, enzymes, and chemical reactions by adding an oxidative biodegradation accelerator to plastics.

The present invention is a polyethylene multilayer film for eco-friendly ice pack packaging with excellent low temperature retention by ice, which is a refrigerant, and excellent impact resistance, puncture resistance, toughness and bag formability of packaging materials, and excellent recyclability after use by uni material. And it relates to an ice pack comprising the same.

An object of the present invention is to develop an ice pack made of a recyclable film made of a uni material, which is excellent in impact resistance, puncture resistance, toughness, and bag formability, in an ice pack using ice that is filled with water and frozen in the packaging material as a refrigerant. to be introduced for use. Looking back on the problems in the prior art, the desired properties were secured by introducing a composite film obtained by laminating a stretched nylon film with excellent impact resistance, puncture resistance and toughness and a polyethylene film with excellent bag formability as a packaging material by dry lamination. It is impossible to recycle as it is made of two or more types of multi-material.

The present inventors found that, unlike a polyethylene unstretched film, in the case of a uniaxially or biaxially stretched polyethylene film, crystallization and orientation of polymer chains are greatly increased, so that excellent impact resistance, puncture resistance and toughness like a stretched nylon film are expressed. In the course of research and development focusing on the fact that it can be, a polyethylene multilayer film including a uniaxially or biaxially stretched polyethylene film and a polyethylene unstretched film having an area stretch ratio of 2.0 or more, more specifically, the polyethylene stretched film When a polyethylene multilayer film with an outer layer and a polyethylene unstretched film as an inner layer is used as a packaging material, all desired properties such as recyclability, impact resistance, low temperature impact resistance, puncture resistance, toughness, and bag formability are achieved by uni material. The present invention was completed by finding surprisingly excellent expression.

The polyethylene multilayer film for ultra-impact-resistant eco-friendly ice pack packaging material of the present invention is characterized in that it comprises a uniaxially or biaxially stretched polyethylene film and a polyethylene unstretched film having an area stretch ratio of 2.0 or more.

The polyethylene stretched film may be a uniaxially stretched polyethylene film stretched in the machine (length) direction by a speed difference between the driven rolls, and the uniaxially stretched film is maintained at a specific temperature above the glass transition temperature and below the melting point in a tenter. It may be a biaxial polyethylene oriented film that is stretched in the width direction and subjected to heat setting. Examples of the commercially available stretched polyethylene film may be, for example, a uniaxially oriented polyethylene film (trade name: calayan) manufactured by Japan Electrochemical Industry Co., or a biaxially oriented polyethylene film manufactured by Nova Chemicals, Canada.

The polyethylene stretched film has an area stretching ratio of 2.0 or more and 100 or less, preferably 5.0 or more. As the area stretching ratio is large, the crystallization and orientation of the polymer chains are greatly increased, so that excellent impact resistance, low temperature impact resistance, puncture resistance characteristics and toughness like a stretched nylon film can be expressed, and the upper limit is not limited thereto.

The density of the stretched polyethylene film is preferably 0.920 g/cm 3 or more and 0.970 g/cm 3 or less, preferably 0.935 g/cm 3 or more and 0.970 g/cm 3 or less. When a polyethylene stretched film having a density in the above range is used, the impact resistance, low temperature impact resistance and puncture resistance characteristics are very excellent, and at the same time, it is advantageous in terms of cost, so that economic efficiency can be secured.

The melting point of the stretched polyethylene film is preferably 115°C or more and 140°C or less, preferably 120°C or more and 138°C or less. When a polyethylene stretched film having a melting point in the above range is used, not only the envelope formability by heat is very excellent, but also the physical properties described in the present invention can be satisfied without using an extremely high areal stretch ratio, so it can be advantageous in terms of cost. have.

The polyethylene multilayer film for the ultra-impact resistant eco-friendly ice pack packaging material may have the polyethylene stretched film as an outer layer and a polyethylene unstretched film as an inner layer. By introducing the polyethylene unstretched film into the inner layer, it is possible to improve the envelope formability by heat.

The polyethylene unstretched film may be used alone, but may be made of a mixture of polyethylene and polyethylene elastomer. When the polyethylene elastomer is included, impact resistance, low temperature impact resistance, and puncture resistance properties can be further improved.

In the present invention, the polyethylene elastomer may be an ethylene-α-olefin copolymer elastomer, etc., for example, Engage by Dow Chemical, Tafmer by Mitsui Chemical, etc., and the Showa hardness of the polyethylene elastomer is 30A to 100A is preferred, but it is not particularly limited as long as it does not impair the purpose of the present invention.

The polyethylene unstretched film may have a single layer, but may have a multilayer structure. For example, by using polyethylene with a low melting point as one layer and a mixture of polyethylene and polyethylene elastomer as another layer, it is possible to improve the envelope formability by heat and at the same time improve the impact resistance, low temperature impact resistance and puncture resistance characteristics.

The polyethylene multilayer film for the eco-friendly ice pack packaging material has the melting point (t1) of the polyethylene stretched film of the outer layer and the melting point (t2) of the polyethylene unstretched film of the inner layer in order to improve bag formability by heat, which satisfies the following formula (1) it could be

Equation (1) t1 - t2 ≥ 10 °C

Specifically, in Formula (1), t1 - t2 may be 10°C or more, 15°C or more, and 20°C or more, and more specifically, for example, 10°C or more and 80°C or less, preferably 15°C or more, more preferably It may be 20° C. or higher, and the upper limit is not particularly limited.

The melting point (t2) of the polyethylene unstretched film of the inner layer is preferably 60°C or more and 125°C or less, preferably 80°C or more and 120°C or less. When a polyethylene unstretched film within the above range is used, bag formability and drop impact resistance are simultaneously excellent, and anti-blocking properties between inner layers of the film are prevented.

In the present invention, the polyethylene used in the stretched polyethylene film and the polyethylene unstretched film may be any one or a mixture of two or more selected from the group consisting of ultra-low-density polyethylene, low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, and high-density polyethylene. Also, it is possible to use a catalyst prepared by any catalyst such as a Ziegler catalyst, a chromium catalyst, or a metallocene catalyst.

In the present invention, any one or more selected from the polyethylene stretched film and the polyethylene unstretched film may further include a commonly used additive. The additive may be a slip agent, an anti-blocking agent, an antioxidant, a UV stabilizer, and the like, but the type or content of the additive is not particularly limited as long as the object of the present invention is not impaired. In particular, it is good to add slip agents and anti-blocking agents because they improve workability and opening properties, and it is also good to prescribe antioxidants and UV stabilizers in terms of durability.

In the present invention, when the oxidative biodegradation promoter is further included in any one or more selected from the polyethylene stretched film and the polyethylene non-stretched film, the polyethylene multilayer film for the ultra-impact resistant eco-friendly ice pack packaging material is buried in a landfill after disposal and is oxidatively biodegraded to be eco-friendly can exert

As the oxidative biodegradation accelerator, a fatty acid metal salt, an acetyl-based organic metal salt, or a mixture thereof may be used.

The metal of the fatty acid metal salt and the acetyl-based organic metal salt may include any one or a mixture of two or more selected from the group consisting of metals selected from the group consisting of alkaline earth metals, transition metals, and rare earth metals.

The fatty acids of the fatty acid metal salt include propionic acid, butyric acid, valeric acid, caproic acid, enantic acid, caprylic acid, pelargonic acid, capric acid, undecylic acid, lauric acid, tridecylic acid, myristic acid, pentadecylic acid, Palmitic acid, margaric acid, stearic acid, nonadecylic acid, arachidic acid, heneicosylic acid, behenic acid, tricosylic acid, lignoceric acid, pentacosylic acid, cerotic acid, heptacosyl acid, montanic acid, nonacosylic acid, melisic acid henatriacntyl acid, oleic acid, linoleic acid, linoleic acid, gamma-linoleic acid, and palmitoleic acid. Among them, lauric acid, myristic acid, palmitic acid and stearic acid. Saturated fatty acids such as oleic acid, linoleic acid and linoleic acid are more preferable, and in the case of unsaturated fatty acids, the contained unsaturated group is easily decomposed by heat or light, so it can be very effective in promoting oxidative decomposition.

By the action of the oxidative biodegradation accelerator, the ultra-impact resistant eco-friendly polyethylene multilayer film for packaging material is reduced to hydrophilic low molecular weight by oxidative decomposition through thermal oxidation, photo-oxidation, etc., and returns to the natural world in a non-toxic state by a mechanism in which biodegradation occurs in two steps. This is the first-stage thermal oxidation (20 to 70°C), oxidative-degradability evaluation (mechanical property measurement, molecular weight measurement) through photooxidation, etc., the second-stage biodegradability evaluation (carbon dioxide emission, biodegradation residue measurement), and the third-stage biodegradation residue The presence or absence of oxidative biodegradability can be determined by evaluating according to ASTM D6954, which consists of a water toxicity test.

The amount of the oxidative biodegradation accelerator to be added is preferably 0.1 to 5 parts by weight, preferably 0.2 to 3 parts by weight, based on 100 parts by weight of the polyethylene or the composition of polyethylene and polyethylene elastoma. When the oxidative biodegradation accelerator is used in the above range, economical and sufficient oxidative biodegradability can be obtained. In particular, since the amount of the oxidative biodegradation accelerator according to the present invention is very small, it has a great advantage of excellent economic efficiency without impairing the mechanical properties of the polyethylene multilayer film for the ultra-impact resistant eco-friendly ice pack packaging material of the present invention.

Examples of commercially available oxidative biodegradation accelerators include P-Life Japan's trade name P-Life (a masterbatch in which a mixture of fatty acid metal salts and lubricants are dispersed in polyolefin resin), Biomaterials' trade name TGR (fatty acid metal salts, fatty acids, and plasticization) Masterbatch in which a mixture such as cellulose is dispersed in polyolefin resin), Grade TGR-001, TGR-00A, TGR-G03, etc., Symphony Environmental PLC’s trade name d2w (masterbatch in which a mixture of fatty acid metal salts is dispersed in polyolefin resin), Grade 95200, 93190, etc. are mentioned.

The method of manufacturing a polyethylene multilayer film for ultra-impact-resistant eco-friendly ice pack packaging material according to the present invention is

a) preparing a uniaxially or biaxially stretched polyethylene film having an area stretching ratio of 2.0 or more; and

b) preparing a polyethylene multilayer film by laminating, thermally laminating, cooling and winding a polyethylene melt melted in one or more extruders and coming out through a T-die on the stretched polyethylene film to be separately supplied;

may include.

Another aspect of the present invention may provide an ice pack manufactured by including the polyethylene multilayer film for the ultra-impact resistant eco-friendly ice pack packaging material. Specifically, the ice pack of the present invention is manufactured by including ice used as a refrigerant and the polyethylene multilayer film for the ice pack packaging material of the present invention, and has excellent toughness and bag formability, as well as excellent impact resistance and puncture resistance. In addition, while having the same physical properties as described above, it is excellent in recyclability and at the same time excellent in oxidative biodegradability.

The refrigerant of the ice pack may basically be ice frozen water, but it may be more effective to use a frozen product in which a non-crosslinked water-soluble polymer is further added to water in order to improve low-temperature retention properties. As the non-crosslinked water-soluble polymer, any one selected from the group consisting of starch, cellulose, chitosan, dextran, hyaluronic acid, pectin, alginic acid, agar, xanthan, beta-cyclodextrin, amylose, salts thereof, derivatives thereof, etc. or a mixture of two or more.

Hereinafter, an example will be given for a detailed description of the present invention, but the present invention is not limited to the following examples, and processing in each of the following examples and comparative examples is the same as in Example 1 unless otherwise specified. was carried out.

Impact resistance, puncture resistance, drop breakage resistance, toughness, bag formability, recyclability and oxidative biodegradability of polyethylene multilayer films and film samples for ice pack packaging prepared according to the following Examples and Comparative Examples were evaluated as follows. .

[Method for evaluating physical properties]

1. Impact resistance

Based on ASTM D1709, the non-breaking maximum dart weight (g) of the sample film was measured using a dart drop impact strength measuring instrument (Toyoseki), and the impact resistance was evaluated in 4 grades as shown in Table 1.

Table 1 below is the impact resistance evaluation criteria.

division ◎ (excellent) ○ (good) △ (normal) X (bad) Maximum non-breaking dart weight (g) 1,000 or more over 500
less than 1,000 300 or more
less than 500 less than 300

2. Puncture resistance characteristics

Based on ASTM D5748, the energy (J) at break of the sample film was measured using a puncture resistance measuring instrument (Ubique, model UPR-digital), and the puncture resistance characteristics were evaluated in 4 grades as shown in Table 2.

Table 2 below is a standard for evaluation of puncture resistance properties.

division ◎ (excellent) ○ (good) △ (normal) X (bad) Energy at break (J) 20 or more 15 or more
less than 20 over 10
less than 15 less than 10

3. Drop breakage resistance

The impact resistance and puncture resistance properties were evaluated at the same time, and the drop breakage resistance was evaluated. Heat-seal two samples of 150mm x 240mm in width and length on three sides, fill with water, heat-seal the other side, and freeze it to make ice pack samples. Five samples of ice packs filled with ice were placed in a box to evaluate the breakage rate that occurs when falling from 1.2 m in consideration of the consumer's shoulder height. The breakage rate was taken as the average of the result values repeated 5 times. In the same way, when falling from the delivery vehicle, the fall breakage rate was evaluated at 2.0m considering the height, and as shown in Table 3, the drop breakage resistance was evaluated as 4 grades. Comprehensive evaluation of drop breakage resistance was determined to be the lowest among the evaluation values of the breakage rate at 2.0m drop and the breakage rate at 1.2m drop. For example, if the 1.2 m drop breakage rate is ○ (good) and 2.0 m drop breakage rate △ (normal), the result of the comprehensive evaluation of fall breakage resistance is △ (normal).

Table 3 below is the evaluation criteria for fall breakage resistance.

division ◎ (excellent) ○ (good) △ (normal) X (bad) Breakage rate at 2.0m drop (%) 0 1 or more
less than 20 20 or more
less than 50 50 or more 1.2m drop
Breakage rate (%) 0 0 1 or more
less than 20 20 or more

4. Toughness

According to ASTM D882, the tensile strength (MPa) and elongation (%) at break of the sample were measured using a universal testing machine (UTM, Tinius Olsen) at a tensile speed of 200 mm/min and a measurement temperature of 23 ° C. As shown, the toughness was evaluated in 4 grades, and the comprehensive evaluation of toughness was judged to be the lowest among the results of tensile strength and elongation. For example, if the tensile strength is ◎ (excellent) and the elongation is X (poor), the overall toughness evaluation result is X (poor).

Table 4 below is the toughness evaluation criteria.

division ◎ (excellent) ○ (good) △ (normal) X (bad) Tensile strength (MPa) over 40 35 or more
less than 40 30 or more
under 35 less than 30 Elongation (%) over 500 over 450
less than 500 over 400
less than 450 less than 400

5. Envelope Formability

Based on ASTM F88, the heat sealing strength (N/15mm) measured using a universal testing machine (UTM, Tinius Olsen) was used as a standard, and as shown in Table 5, the envelope formability by heat was evaluated in 4 grades.

Table 5 below is the evaluation criteria for bag formability.

division ◎ (excellent) ○ (good) △ (normal) X (bad) Heat sealing strength (N/15mm) 6 or more 3 or more
less than 6 2 or more
less than 3 less than 2

6. Recyclability

According to KS M0024 (infrared spectroscopic analysis method general rule) according to the packaging material material and structure of the 「Packaging Material Recycling Ease Rating Evaluation Criteria」 (notified by the Ministry of Environment), excellent recyclability in the case of a single polyethylene material (uni-material) ( ◎), and if several other components other than polyethylene appear due to multi-material, it was judged as poor recyclability (X).

7. Oxidative biodegradability

1st step thermal oxidation (20 ~ 70℃), oxidative degradability evaluation through photooxidation (mechanical property measurement, molecular weight measurement), 2nd step biodegradability evaluation (carbon dioxide emission, biodegradation residue measurement), and 3rd step biodegradation residue It was evaluated according to ASTM D6954, which consists of a water toxicity test, and if it passed all the oxidative biodegradability evaluation criteria, it was judged as 'acceptable' or 'unsuitable' if any one failed.

[Example 1]

First, prepare a uniaxial polyethylene stretched film (trade name: calalyan Grade YA5, OPE-A) with a stretch ratio or area stretch ratio of 5.5, a density of 0.957 g/cm3, a melting point of 133 ° C, and a thickness of 50 μm from Japan Electrochemical Industry Company as a uniaxial polyethylene oriented film. did. Linear low-density polyethylene (SK Global Chemical, grade smart121, PE-A) with a density of 0.912 g/cm 3 , a melting point of 111° C., and a melt index of 1.0 g/min (2.16 kg, 190° C.) was prepared.

While feeding the polyethylene stretched film OPE-A in the unwinder, PE-A is injected into the extruder hopper, extruded under 160-180°C conditions, and the polyethylene melt coming out through the T-die is laminated on the polyethylene stretched film OPE-A, After thermal lamination, cooling, and winding, a polyethylene two-layer film having a final thickness of 150 μm was prepared, and the results are shown in Table 6 by evaluating impact resistance, puncture resistance, drop breakage resistance, toughness, bag formability and recyclability. shown in

[Example 2]

PE-A of Example 1 was prepared as a raw material for the inner layer. In addition, a polyethylene elastomer (SK Global Chemical, grade solumer 871, PEE-A) having a density of 0.868 g/cm 3 , a melting point of 62° C., and a melt index of 1.0 g/min (2.16 kg, 190° C.) was prepared. A PE-A/PEE-A (=70/30, weight ratio) composition was prepared as a raw material for the middle layer.

PE-A/PEE-A (= 70/30) in T-die casting equipment equipped with two extruders while feeding the polyethylene stretched film OPE-A of Example 1 for the outer layer to the unwinder for the outer layer , weight ratio) The composition is injected, PE-A is injected into the inner layer extruder hopper, and the polyethylene melt coming out through the T-die is co-extruded under the conditions of 160 ~ 180 ℃, laminated and thermally laminated on the polyethylene stretched film OPE-A After cooling and winding, a polyethylene three-layer film with a final thickness of 150 μm was prepared, and the results are shown in Table 6 by evaluating impact resistance, puncture resistance, drop breakage resistance, toughness, bag formability and recyclability. .

[Example 3]

First, as a biaxial polyethylene stretched film, a biaxial polyethylene stretched film (OPE-B) having an area stretch ratio of 45 (lengthwise stretch ratio 5.0, transverse direction stretch ratio 9.0), a density of 0.965 g/cm 3 , a melting point of 136 ° C., and a thickness of 45 μm from Nova Chemicals of Canada ) was prepared.

A polyethylene two-layer film having a thickness of 150 μm was prepared in the same manner as in Example 1 except that the biaxially stretched polyethylene film (OPE-B) was used for the outer layer. Impact resistance, puncture resistance, and drop breakage resistance were prepared. , toughness, bag formability and recyclability were evaluated, and the results are shown in Table 6.

[Example 4]

A polyethylene three-layer film having a thickness of 150 μm was prepared in the same manner as in Example 2 except that the biaxially stretched polyethylene film (OPE-B) of Example 3 was used for the outer layer, and impact resistance, puncture resistance, and drop Breakage resistance, toughness, bag formability and recyclability were evaluated, and the results are shown in Table 6.

[Example 5]

As an oxidative biodegradation accelerator, using polyethylene containing 1.2 parts by weight of d2w (polyolefin masterbatch containing fatty acid metal salt mixture) Grade 95200 of Symphony Environmental PLC in an amount of 1.2 parts by weight based on 100 parts by weight of polyethylene, area stretch ratio 63 (lengthwise stretch ratio 7.0, width direction stretch ratio) 9.0), a density of 0.967 g/cm 3 , a melting point of 137° C. and a thickness of 40 μm, a biaxially stretched polyethylene film (Nova Chemicals, Canada, OPE-C) was prepared.

A polyethylene two-layer film having a thickness of 150 μm was prepared in the same manner as in Example 1 except that the biaxially stretched polyethylene film (OPE-C) was used for the outer layer. Impact resistance, puncture resistance, and drop breakage resistance were prepared. , toughness, bag formability, recyclability and oxidative biodegradability were evaluated, and the results are shown in Table 6.

[Comparative Example 1]

An unstretched polyethylene single-layer film having a thickness of 150 μm was prepared in the same manner as in Example 1 except that no polyethylene oriented film was used and only PE-A of Example 1 was used. Breakability, toughness, bag formability and recyclability were evaluated, and the results are shown in Table 6.

[Comparative Example 2]

In the T-die casting equipment equipped with three extruders, the PE-A/PEE-A (= 70/30, weight ratio) composition was injected into the extruder hopper for the middle layer, and PE-A was injected into the extruder hoppers for the outer and inner layers. An unstretched polyethylene three-layer film having a thickness of 150 μm was prepared by co-extrusion under the conditions of 160 to 180° C. and molded to a thickness ratio of the outer layer/middle layer/inner layer (=25/50/25), and the impact resistance, puncture resistance characteristics, Drop breakage resistance, toughness, bag formability and recyclability were evaluated, and the results are shown in Table 6.

[Comparative Example 3]

A uniaxially stretched polyethylene monolayer film having a thickness of 150 μm was prepared in the same manner as in Example 1 except that only the OPE-A of Example 1 was used without using a polyethylene unstretched film. Impact resistance, puncture resistance characteristics, Drop breakage resistance, toughness, bag formability and recyclability were evaluated, and the results are shown in Table 6.

[Comparative Example 4]

First, a 25 μm-thick biaxially stretched nylon film (Kolon Industries, trade name AMIDROLL grade CRB01, NY-A) was prepared. A nylon film (outer layer)/polyethylene film (inner layer) two-layer film having a thickness of 150 μm was prepared in the same manner as in Example 1 except that the biaxially stretched nylon film (NY-A) was used for the outer layer, and Impact properties, puncture resistance characteristics, drop breakage resistance, toughness, bag formability and recyclability were evaluated, and the results are shown in Table 6.

division impact resistance puncture resistance
characteristic fall
breakage resistance toughness envelope
formability recyclability Oxidative biodegradability Example 1 ○ ○ ○ ○ ○ ◎ - Example 2 ◎ ◎ ◎ ◎ ◎ ◎ - Example 3 ◎ ◎ ◎ ◎ ◎ ◎ - Example 4 ◎ ◎ ◎ ◎ ◎ ◎ - Example 5 ◎ ◎ ◎ ◎ ◎ ◎ fitness Comparative Example 1 X X X X X ◎ - Comparative Example 2 △ △ △ △ X ◎ - Comparative Example 3 ○ ○ ○ ○ X ◎ - Comparative Example 4 ○ ○ ○ ◎ ◎ X -

Examples 1 to 4 in the case of a polyethylene multi-layer film comprising the polyethylene stretched film according to the present invention as an outer layer and a polyethylene unstretched film as an inner layer, and a composition of polyethylene or polyethylene and a polyethylene elastomer according to the prior art When comparing Comparative Examples 1 and 2, which are single-layer or multi-layer films used, in the case of the polyethylene multi-layer film including the stretched polyethylene film according to the present invention, the recyclability of the packaging material is excellent as well as impact resistance, puncture resistance, and drop resistance. It can be seen that breakage, toughness and envelope formability are all excellent. In addition, in the case of the uniaxially stretched polyethylene monolayer film of Comparative Example 3, it can be seen that the impact resistance, drop impact resistance, toughness and puncture resistance properties are good, but the envelope formability is remarkably insufficient, and the stretched nylon film of Comparative Example 4 In the case of a polyethylene multilayer film containing a, it can be seen that impact resistance, puncture resistance, drop breakage resistance, toughness, bag formability, etc. are good, but recyclability is extremely poor.

In addition, in the case of the polyethylene multilayer film comprising the polyethylene film containing the oxidative biodegradation accelerator of Example 5, the packaging material has excellent recyclability, impact resistance, puncture resistance, drop breakage resistance, toughness and bag formability as well as excellent oxidation resistance. It can be seen that the biodegradability is also excellent.

As can be seen from the above examples, the ice pack according to the present invention has excellent low-temperature retention by ice, which is the refrigerant, and excellent impact resistance, puncture resistance, drop breakage resistance, toughness and bag formability of the packaging material. It has excellent recyclability after use and can be usefully used as an eco-friendly ice pack that is oxidized and biodegraded if buried in a landfill.

Claims (13)

Polyethylene multilayer film for ice pack packaging material, which is manufactured by thermally laminating a polyethylene unstretched film that is melt-extruded on a uniaxially or biaxially stretched polyethylene film having an area stretching ratio of 2.0 or more, and has an elongation of 450% or more. According to claim 1,
A polyethylene multilayer film for ice pack packaging material having a density of the polyethylene stretched film of 0.920 g/cm 3 or more and 0.970 g/cm 3 or less. According to claim 1,
A polyethylene multilayer film for an ice pack packaging material having a melting point of 115°C or more and 140°C or less of the stretched polyethylene film. According to claim 1,
The polyethylene multi-layer film for the ice pack packaging material includes the polyethylene oriented film as an outer layer and a polyethylene unstretched film as an inner layer. 5. The method of claim 4,
The polyethylene non-stretched film is a polyethylene multilayer film for ice pack packaging material consisting of polyethylene alone or a mixture of polyethylene and polyethylene elastomer. 5. The method of claim 4,
The polyethylene multi-layer film for the ice pack packaging material that the polyethylene unstretched film has a single-layer or multi-layer structure. 5. The method of claim 4,
The polyethylene multilayer film for the ice pack packaging material has the melting point (t1) of the polyethylene stretched film of the outer layer and the melting point (t2) of the polyethylene unstretched film of the inner layer satisfying the following formula (1). A polyethylene multilayer film for an ice pack packaging material.
Equation (1) t1 - t2 ≥ 10 °C 8. The method of claim 7,
Polyethylene multilayer film for ice pack packaging material having a melting point (t2) of the polyethylene unstretched film of the inner layer of 60°C or higher and 125°C or lower. According to claim 1,
The polyethylene used in the polyethylene stretched film and the polyethylene unstretched film is any one or a mixture of two or more selected from the group consisting of ultra low density polyethylene, low density polyethylene, linear low density polyethylene, medium density polyethylene and high density polyethylene. Polyethylene multilayer film for ice pack packaging . According to claim 1,
Any one or more selected from the polyethylene stretched film and the polyethylene unstretched film further comprises an oxidative biodegradation accelerator, a polyethylene multilayer film for ice pack packaging. 11. The method of claim 10,
The oxidative biodegradation accelerator is a fatty acid metal salt, an acetyl-based organic metal salt, or a mixture thereof. A polyethylene multilayer film for an ice pack packaging material. a) preparing a uniaxially or biaxially stretched polyethylene film having an area stretching ratio of 2.0 or more; and
b) melting in one or more extruders and producing a polyethylene multilayer film by laminating, thermally laminating, cooling and winding on the polyethylene stretched film to which a polyethylene melt coming out through a T-die is separately supplied
A method for manufacturing a polyethylene multilayer film for ice pack packaging material having an elongation of 450% or more. An ice pack comprising the polyethylene multilayer film for the ice pack packaging material of any one of claims 1 to 11.