KR102561213B1 - Biodegradable sheet and manufacturing method for the same - Google Patents

Abstract

Disclosed is a biodegradable sheet containing a biodegradable masterbatch that is easily decomposed in a natural environment with light and air and a decomposition rate controllable and a method for manufacturing the same.
Such a biodegradable sheet includes 70 to 95% by weight of at least one resin selected from polyethylene, polypropylene, polymethylpentene, polybutene and polystyrene and 5 to 30% by weight of a biodegradable masterbatch.

Description

Biodegradable sheet and its manufacturing method {BIODEGRADABLE SHEET AND MANUFACTURING METHOD FOR THE SAME}

The disclosure herein relates to a biodegradable sheet and a manufacturing method thereof.

Unless otherwise indicated herein, material described in this section is not prior art to the claims in this application, and inclusion in this section is not an admission that it is prior art.

Recently, as the proportion of double-income households and single-person households increases, the consumption of retort-type home meals or delivery food increases, and along with this, the amount of plastic waste due to disposable containers is also increasing. Moreover, concerns about plastic waste are growing as the use of delivered food has increased rapidly from 33% to 52% after the outbreak of Corona 19.

Therefore, in order to reduce the use of a vast amount of disposable containers used in food packaging and delivery, manufacturers of the product are striving to research and develop eco-friendly containers that are biodegradable in nature.

As an example of a technology related to this, Patent Document 1 contains 79.0 to 89.0% by weight of polylactic acid, 1.0 to 5.0% by weight of PBAT, a biodegradable polymer, 0.1 to 1.0% by weight of a resin polymer composed of metablen, 7.5 to 14.5% by weight of talc, and a dispersant. 0.2 to 0.6% by weight, 0.1 to 0.3% by weight of primary antioxidants, 0.1 to 0.3% by weight of secondary antioxidants, based on the total weight of the sheet body and the functional coating layer, polylactic acid 79.0 to 79.0% by weight 89.6% by weight, 1.0 to 5.0% by weight of PBAT, a biodegradable polymer, 0.1 to 1.0% by weight of a resin polymer composed of metablen, 7.5 to 14.5% by weight of talc, 0.2 to 0.6% by weight of a dispersant, 0.1 to 0.3% by weight of a primary antioxidant, A biodegradable sheet container with high heat resistance composed of a functional coating layer coated on the inner bottom surface of the sheet body composed of 0.1 to 0.3% by weight of a secondary antioxidant and 0.05 to 0.5% by weight of basalt as a far-infrared active material is disclosed. , In Patent Document 2, biodegradation achieved by heating and pressurizing a composition composed of 50 to 60 parts by weight of rice husk, 12 to 18 parts by weight of melamine resin, 3 to 7 parts by weight of titanium dioxide, 3 to 7 parts by weight of starch, and 20 to 30 parts by weight of water. A container of castle starch and a method for making the same are disclosed.

However, Patent Documents 1 and 2 both use starch-extracted raw materials or starch as raw materials, so they are environmentally friendly, but decompose only under composting environmental conditions, have limitations in that the decomposition rate cannot be adjusted, and have problems in difficult molding.

Republic of Korea Patent No. 10-2264102 (2021.06.07) Republic of Korea Patent No. 10-0824687 (2008.04.17)

It is an object of the present invention to provide a biodegradable sheet that decomposes under natural conditions of light and air, and that can adjust the decomposition rate and is relatively free to form, and a method for manufacturing the same.

In addition, it is not limited to the technical problems as described above, and it is obvious that other technical problems may be derived from the following description.

According to one embodiment of the disclosed contents, the biodegradable sheet includes 70 to 95% by weight of one or more resins selected from polyethylene, polypropylene, polymethylpentene, polybutene and polystyrene and 5 to 30% by weight of a biodegradable masterbatch, , The biodegradable masterbatch contains unsaturated fatty acids extracted from at least one selected from corn, tapioca, rice, potato, wheat, cassava and olive.

According to another embodiment of the disclosed subject matter, the biodegradable sheet is a core composed of 70 to 95% by weight of at least one resin selected from polyethylene, polypropylene, polymethylpentene, polybutene and polystyrene and 5 to 30% by weight of a biodegradable masterbatch. 70 to 90% by weight of one or more resins selected from polyethylene, polypropylene, polymethylpentene, polybutene and polystyrene, and 10 to 30% by weight of a biodegradable masterbatch. It includes first and second outer layers configured, wherein the biodegradable masterbatch includes unsaturated fatty acids extracted from at least one selected from corn, tapioca, rice, potato, wheat, cassava, and olive.

According to another embodiment of the disclosed subject matter, the biodegradable sheet comprises 85 to 95% by weight of at least one resin selected from polyethylene, polypropylene, polymethylpentene, polybutene and polystyrene, 4 to 15% by weight of a biodegradable masterbatch, A core foam layer composed of 0.1 to 0.5% by weight of a nucleating agent and 70 to 90% by weight of at least one resin selected from polyethylene, polypropylene, polymethylpentene, polybutene and polystyrene, provided on the upper and lower surfaces of the core foam layer, respectively; , Including first and second outer layers composed of 10 to 30% by weight of a biodegradable masterbatch, wherein the biodegradable masterbatch is unsaturated extracted from at least one selected from corn, tapioca, rice, potato, wheat, cassava and olive contains fatty acids;

According to another embodiment of the disclosed subject matter, a method for manufacturing a biodegradable sheet includes (a) preparing a raw material, (b) co-extruding and rolling the raw material into a sheet, and (c) co-extruding and rolling the raw material. A step of cooling the sheet, wherein steps (a) to (c) are performed by a T-die sheet extruder, wherein the T-die sheet extruder is coupled to a supply unit for supplying the raw material and the supply unit to form a sheet An extrusion die for extruding into a shape, a plurality of calender rolls connected to the extrusion die to roll the sheet extruded from the extrusion die, and a cooling unit located behind the plurality of calender rolls to cool the moving sheet.

According to one embodiment disclosed herein, the biodegradable sheet and its manufacturing method include a biodegradable masterbatch, so that it is easily degraded in a natural environment with light and air, and the decomposition rate can be adjusted.

In addition, by adding only a biodegradable masterbatch to a commonly used resin, the process is relatively simple and the molding is free.

In addition, there is an eco-friendly effect by recovering the waste scrap discarded in the manufacturing process of the biodegradable sheet and reusing it to manufacture the biodegradable sheet.

1 is an exploded perspective view showing a biodegradable sheet according to an embodiment of the disclosure disclosed herein.
Figure 2 is an exploded perspective view showing a biodegradable sheet according to another embodiment of the disclosure disclosed herein.
Figure 3 is a cross-sectional view of Figure 2;
FIG. 4 is an optical micrograph of FIG. 3 .
Figure 5 is a process chart for explaining a method of manufacturing a biodegradable sheet according to another embodiment of the information disclosed herein.
6 and 7 are schematic diagrams showing a T-die sheet extruder.

Hereinafter, with reference to the accompanying drawings, look at the configuration and operation effects of preferred embodiments of the disclosure. For reference, in the drawings below, each component is omitted or schematically illustrated for convenience and clarity, and the size of each component does not reflect the actual size. In addition, like reference numerals refer to like components throughout the specification, and reference numerals for like components in individual drawings will be omitted.

The biodegradable sheet disclosed herein applies an oxidative decomposition method that is decomposed in a natural environment with light and air, unlike the conventional hydrolysis method in which a hydrolysis method is applied only in a compost environment. Therefore, the biodegradable sheet may be degraded by being reduced in molecular weight with water and carbon dioxide, and the biodegradable sheet may collapse and become fine particles.

In this embodiment, the biodegradable sheet may be composed of a resin and a biodegradable masterbatch, may have a thickness in the range of 1.0 to 1.5 mm, and may be formed by co-extrusion with a T-die sheet extruder. These biodegradable sheets can be widely used by applying them to various applications such as fruit and vegetable packaging materials, agricultural multi-films, various trays, food containers, and plastic bags. On the other hand, waste scrap discarded in the manufacturing process of the biodegradable sheet can be recovered and reused to manufacture the biodegradable sheet, and specifically, it is preferable to reuse it by adding it to a core layer and a core foam layer to be described later.

The resin is at least one selected from polyethylene (PE), polypropylene (PP), polymethylpentene (PMP), polybutene (PB) and polystyrene (PS), preferably polymethylpentene (PS). It may be propylene (Polypropylene, PP). For example, the resin may have a melt index of 0.5 to 1.0 g/10 min, a heat deflection temperature of 105 to 120° C., and a flexural modulus of 1300 to 1500 MPa, but is not limited thereto.

The biodegradable masterbatch is a material added to microbially degrade the resin by oxidative degradation, and may include unsaturated fatty acids extracted from at least one selected from corn, tapioca, rice, potato, wheat, cassava, and olive.

1 is an exploded perspective view showing a biodegradable sheet according to one embodiment of the disclosure disclosed herein, Figure 2 is an exploded perspective view showing a biodegradable sheet according to another embodiment, Figure 3 is a cross-sectional view of FIG. 4 is an optical micrograph of FIG. 3 .

In this embodiment, the biodegradable sheet may be formed of a single layer as shown in FIG. 1, but may also be formed of three layers as shown in FIG. 2. Since the composition of the resin and the biodegradable masterbatch has been described in detail above, duplicate descriptions will be omitted below.

Referring to Figure 1, the biodegradable sheet 100 may be formed of a single layer, and may be composed of 70 to 95% by weight of the resin and 5 to 30% by weight of the biodegradable masterbatch. If the content of the biodegradable masterbatch is less than 5% by weight, the biodegradable sheet 100 may be difficult to biodegrade due to ultraviolet rays, heat, and oxygen, and if it exceeds 30% by weight, texture and flexibility may be adversely affected. so it is not desirable

Meanwhile, in this embodiment, one or more additives selected from an antioxidant, a slip agent, a weathering stabilizer, an antistatic agent, and a pigment may be further added in addition to the resin and the biodegradable masterbatch. For example, the additive may be added in a certain amount within a range that does not impair the physical properties of the biodegradable sheet 100, and may be added in an amount of 0.01 to 5 parts by weight based on 100 parts by weight of the mixture of the resin and the biodegradable masterbatch.

Referring to Figures 2 to 4, the biodegradable sheet 200 may be formed of three layers, specifically composed of a core layer 210 and first and second outer layers 220 and 230 or core foam It may be composed of a layer 211 and first and second outer layers 220' and 230'.

In another embodiment, the biodegradable sheet 200 may be composed of a core layer 210 and first and second outer layers 220 and 230 . The core layer 210 may be composed of 70 to 95% by weight of one or more resins selected from polyethylene, polypropylene, polymethylpentene, polybutene and polystyrene and 5 to 30% by weight of a biodegradable masterbatch, and the first and second 2 The outer layers 220 and 230 are provided on the upper and lower surfaces of the core layer 210, respectively, and contain 70 to 90% by weight of at least one resin selected from polyethylene, polypropylene, polymethylpentene, polybutene and polystyrene, and biodegradable It may consist of 10 to 30% by weight of the castle masterbatch. The first and second outer layers 220 and 230 will be described in detail below.

In another embodiment, the biodegradable sheet 200 may include a core foam layer 211 and first and second outer layers 220' and 230'.

The core foam layer 211 is a layer positioned in the middle, and may be formed to a thickness of 0.5 to 0.7 mm, preferably 0.6 mm, and has a foaming ratio of 5 to 25% by using one or more gases selected from carbon dioxide gas and nitrogen gas. It is possible to form a foamed cell having flexibility, and at this time, the average cell diameter may satisfy a range of 10 to 110 μm. If the expansion ratio is less than 5%, the raw material cost reduction effect may be insignificant, and if it exceeds 25%, the thickness of the sheet may become thicker than necessary. When the above-mentioned range is satisfied, it is possible to maintain excellent quality during post-processing while reducing raw material costs.

For example, the core foam layer 211 may be composed of 85 to 95% by weight of the resin, 4 to 15% by weight of the biodegradable masterbatch, and 0.1 to 0.5% by weight of the nucleating agent. At this time, the content of the biodegradable masterbatch is 4% by weight. If it is less than %, it may be difficult for the biodegradable sheet 200 to be biodegraded due to ultraviolet rays, heat, and oxygen, and if it exceeds 15% by weight, it is difficult to achieve the target foaming rate as well as adversely affecting texture and flexibility. This is not desirable because it can

On the other hand, the nucleating agent is a material added to improve productivity by increasing the crystallization rate of the resin and shortening the cycle time in the extrusion molding of the resin. Sorbitol (1,3:2,4-Bis(3,4-dimethyldibenzylidene)Sorbitol), Bis(p-methyldibenzylidene)Sorbitol and Substituted Dibenzylidene Sorbitol), preferably 1,3:2,4-bis(3,4-dimethyldibenzylidene) sorbitol (1,3:2,4-Bis(3,4-dimethyldibenzylidene)Sorbitol) and bis(p-methyldibenzylidene)sorbitol in a weight ratio of 1:1 to 2.

The first and second outer layers 220' and 230' are provided on the upper and lower surfaces of the core foam layer 211, respectively, and may be formed to a thickness of 0.1 to 0.5 mm, preferably 0.2 to 0.4 mm, and resin. It may be composed of 70 to 90% by weight and 10 to 30% by weight of the biodegradable masterbatch. If the content of the biodegradable masterbatch is less than 10% by weight, it may be difficult for the biodegradable sheet 200 to be biodegraded due to ultraviolet rays, heat, and oxygen, and if it exceeds 30% by weight, it adversely affects texture and flexibility. However, it is undesirable because quality problems may occur during vacuum forming.

Meanwhile, in the present embodiment, in the core foam layer 211 and the first and second outer layers 220' and 230', at least one selected from an antioxidant, a slip agent, a weathering stabilizer, an antistatic agent, and a pigment, in addition to the above-mentioned composition. Additives may be further added. For example, additives may be added in a certain amount within a range that does not impair the physical properties of the biodegradable sheet 200, and in the case of the core foam layer 211, 0.01 parts by weight based on 100 parts by weight of the mixture of the resin, the biodegradable master batch, and the nucleating agent. ~ 5 parts by weight, and in the case of the first and second outer layers 220 and 230, 0.01 to 5 parts by weight based on 100 parts by weight of the mixture of the resin and the biodegradable masterbatch.

Hereinafter, a method for manufacturing a biodegradable sheet disclosed herein will be described in detail with reference to the drawings.

Figure 5 is a process chart for explaining the manufacturing method of the biodegradable sheet disclosed herein. Hereinafter, a method for manufacturing a biodegradable sheet according to this embodiment will be described with reference to this.

Referring to Figure 5, first prepare a raw material (S10).

In the case of manufacturing a single-layer sheet, a resin and a biodegradable masterbatch are prepared as raw materials, and in the case of manufacturing a three-layer sheet, a core foam layer composition and a first and second outer layer composition may be prepared as raw materials, respectively, using an agitator It is preferable to prepare by mixing each raw material using. The core foam layer composition may include a resin, a biodegradable masterbatch, and a nucleating agent, and the first and second outer layer compositions may include a resin and a biodegradable masterbatch.

Then, the raw material is co-extruded and rolled to form a sheet (S20)

The raw material prepared in step S10 may be co-extruded at a temperature of 190 to 230 ° C and rolled at a temperature of 60 to 70 ° C to form a sheet. In addition, in the case of forming a three-layer sheet, gas is not mixed in the case of forming the core layer, but in the case of forming the core foam layer, at least one gas selected from carbon dioxide gas and nitrogen gas is added to the composition of the core foam layer during co-extrusion. It can be mixed and foamed.

If the co-extrusion temperature is less than 190 ° C, it may be difficult to mold into a desired shape, and if it exceeds 230 ° C, physical properties may change, which is not preferable.

If the rolling temperature is less than 60°C, the sheet may be rapidly cooled, and if it exceeds 70°C, it may be remelted.

Finally, it is cooled (S30).

The coextruded and rolled sheet in step S20 may be cooled using cooling water.

On the other hand, the biodegradable sheets 100 and 200 according to this embodiment may be implemented by the T-die sheet extruder 1 shown in FIGS. 4 and 5, the T-die sheet extruder 1, A supply unit 10 for supplying raw materials, extrusion dies 20 and 20' coupled to the supply unit 10 and extruded in a sheet shape, and connected to the extrusion dies 20 and 20' to extrude the extrusion dies 20 and 20 A plurality of calender rolls 30 for rolling the sheets 100 and 200 extruded from '), and a cooling unit positioned at the rear of the plurality of calender rolls 30 to cool the moving sheets 100 and 200 ( 40) may be included.

As shown in FIG. 4, the supply unit 10 may include only one supply unit 10, but as shown in FIG. 5, the first supply unit 11 for supplying the composition of the core foam layer, and the first and second supply units 10. It may also be composed of second and third supply units 12 and 13 supplying the composition of the two outer layers. The first supply unit 11 is connected to the first flow path 21 to be described later to melt and supply the composition of the core foam layer, and the second and third supply units 12 and 13 are connected to the second and third supply units 12 and 13 to be described later. It is connected to the three flow paths 22 and 23 so that the first and second outer layer compositions can be melted and supplied, respectively.

The extrusion dies 20 and 20' may have only one flow path as shown in FIG. 6, but as shown in FIG. 7, the first flow path 21 and the upper and lower portions of the first flow path 21 It consists of second and third flow passages 22 and 23 spaced apart from each other, the composition of the core foam layer is supplied to the first flow passage 21, and the second and third flow passages 22 and 23 are Compositions of the first and second outer layers may be supplied respectively.

The plurality of calender rolls 30 may roll the sheets 100 and 200 extruded from the extrusion dies 20 and 20' at a temperature of 60 to 70°C.

The cooling unit 40 sprays first cooling water in a vertical direction to the top and bottom of the coextruded and rolled biodegradable sheets 100 and 200 transported by the roller table to cool them, and then sprays second cooling water in an oblique direction. It is possible to remove moisture present in the upper and lower portions of the biodegradable sheets 100 and 200.

<Examples 1 to 4>

A biodegradable sheet composed of a single layer having a thickness of 1.2 mm was prepared by co-extruding and rolling with the ingredients and contents shown in Table 1 using a T-die sheet extruder.

The content in Table 1 is % by weight.

division Example 1 Example 2 Example 3 Example 4 polypropylene 88 82 76 70 Biodegradable Masterbatch 12 18 24 30

<Examples 5 to 7>

By co-extruding and rolling with the components and contents of each layer shown in Table 2 using a T-die sheet extruder, a biodegradable sheet composed of three layers having a core foam layer of 0.6 mm and a thickness of 0.3 mm each of the first and second outer layers was obtained. manufactured.

During co-extrusion, a nitrogen/carbon dioxide mixed gas was mixed into the core foam layer to form foam cells with an expansion ratio of 20%, and 1,3:2,4-bis(3,4-dimethyldibenzylidine ) Sorbitol and bis(p-methyldibenzylidine)sorbitol were mixed at a weight ratio of 1:2 and used.

The content of waste scrap is based on 100 parts by weight of the core foam layer.

In Table 2, the contents of the core foam layer and the first and second outer layers are % by weight, and the contents of the waste scrap are parts by weight.

division Example 5 Example 6 Example 7 core foam layer polypropylene 89.7 89.7 89.7 Biodegradable Masterbatch 10 10 10 nucleating agent 0.3 0.3 0.3 waste scrap 2 2 2 First and second outer layers polypropylene 90 80 70 Biodegradable Masterbatch 10 20 30

<Comparative Example 1>

Biodegradable sheets were prepared in the same manner as in Examples 1 to 4, except that 100% by weight of polylactic acid (PLA) was used instead of polypropylene and the biodegradable masterbatch.

<Comparative Example 2>

100% by weight of PLA (Poly lactic acid) is used instead of polypropylene, biodegradable masterbatch and nucleating agent as the core foam layer, and PLA (Poly lactic acid) is used instead of polypropylene and biodegradable masterbatch as the first and second outer layers Biodegradable sheets were prepared in the same manner as in Examples 5 to 7, except that 100% by weight was used.

Experimental Example 1. Evaluation of physical properties and biodegradability

The physical properties and biodegradability of Examples 1 to 7 and Comparative Examples 1 and 2 were evaluated by the following method, and the results are shown in Table 3.

<Evaluation method>

(1) Evaluation of thickness uniformity

The thickness deviation in the width direction was measured using an optical microscope (BX53M, Olympus), and was evaluated as excellent, average, or poor.

(2) Formability evaluation

The appearance of the sheet was visually checked and evaluated as excellent, average, or poor.

(3) Container quality evaluation

The sheets of Examples 1 to 7 and Comparative Examples 1 and 2 were vacuum thermoformed into the shapes shown in Figs.

(4) Evaluation of biodegradability

The sheets of Examples 1 to 7 and Comparative Examples 1 and 2 were prepared in a size of 10 cm wide × 10 cm long and buried in crop soil, and after 6 months, if the shape completely collapsed, it was excellent, if the shape partially collapsed, it was normal, and if there was no change It was evaluated as poor.

division thickness uniformity sheet formability container quality biodegradable Example 1 ◎ ◎ ◎ commonly Example 2 ◎ ◎ ◎ commonly Example 3 ○ ○ ○ Great Example 4 ○ ○ ○ Great Example 5 ◎ ◎ ◎ Great Example 6 ◎ ○ ○ Great Example 7 ○ ○ △ Great Comparative Example 1 ○ ◎ ○ error Comparative Example 2 ○ ○ △ error ◎: Excellent, ○: Normal, △: Insufficient

Referring to Table 3, it was found that Examples 1 to 4 were superior to Comparative Example 1 in terms of thickness uniformity, moldability and container quality. 4 was superior in biodegradability evaluation compared to Examples 1 and 2. Therefore, it was confirmed that the content of the biodegradable masterbatch affects the biodegradation rate. In addition, Examples 5 to 7 were found to be superior to Comparative Example 2 in evaluation of biodegradability as well as evaluation of thickness uniformity and sheet formability. In addition, it was confirmed that the presence or absence of foaming affects the biodegradation period as the biodegradability was better in the configuration provided with the core foam layer under the same conditions of the content of the biodegradable masterbatch.

The disclosed content is only an example, and can be variously modified and implemented by those skilled in the art without departing from the subject matter of the claim claimed in the claims, so the protection scope of the disclosed content is limited to the specific It is not limited to the examples.

1: T-die sheet extruder 10: feed section
11: first supply unit 12, 13: second and third supply unit
20, 20': extrusion die 21: first flow path
22, 23: second and third passages 30: plurality of calender rolls
40: cooling unit 100, 200: biodegradable sheet
210: core layer 211: core foam layer
220, 220', 230, 230': first and second outer layers

Claims (10)

delete delete A core foam layer composed of 85 to 95% by weight of at least one resin selected from polyethylene, polypropylene, polymethylpentene, polybutene and polystyrene, 4 to 15% by weight of a biodegradable masterbatch, and 0.1 to 0.5% by weight of a nucleating agent; and
It is provided on the upper and lower surfaces of the core foam layer, respectively, and is composed of 70 to 90% by weight of at least one resin selected from polyethylene, polypropylene, polymethylpentene, polybutene and polystyrene, and 10 to 30% by weight of a biodegradable masterbatch. Including; first and second outer layers,
The biodegradable masterbatch is a biodegradable sheet, characterized in that it comprises an unsaturated fatty acid extracted from at least one selected from corn, tapioca, rice, potato, wheat, cassava and olive.
According to claim 3,
The biodegradable sheet, characterized in that the resin has a melt index of 0.5 ~ 1.0g / 10min, a heat distortion temperature of 105 ~ 120 ℃, and a flexural modulus of 1300 ~ 1500MPa.
According to claim 3,
The nucleating agent includes at least one selected from 1,3:2,4-bis(3,4-dimethyldibenzylidine) sorbitol, bis(p-methyldibenzylidine) sorbitol, and substituted dibenzylidine sorbitol. Characterized by a biodegradable sheet.
According to claim 3,
The core foam layer has a thickness of 0.5 to 0.7 mm, and the first and second outer layers have a thickness of 0.1 to 0.5 mm.
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