KR102609633B1 - Biodegradable polymeric composition comprising thermoplastic starch for flexible film products - Google Patents

Abstract

The present invention relates to a biodegradable polymer composition for producing a soft film containing thermoplastic starch, and specifically, as a biodegradable polymer, polybutylene adipate terephthalate (PBAT); Thermoplastic starch (TPS) as a biodegradable natural polymer material; It relates to a biodegradable polymer composition for manufacturing a soft film containing 2,3-epoxypropyl methacrylate as a binder and EBS (Ethylene bis-stearamide) as a dispersant. The biodegradable polymer composition for manufacturing the soft film of the present invention uses biodegradable polymers, can be biodegraded even in general soil, and has excellent physical properties.

Description

Biodegradable polymer composition for producing a flexible film containing thermoplastic starch {BIODEGRADABLE POLYMERIC COMPOSITION COMPRISING THERMOPLASTIC STARCH FOR FLEXIBLE FILM PRODUCTS}

The present invention relates to a biodegradable polymer composition for producing a soft film containing thermoplastic starch, and specifically, as a biodegradable polymer, polybutylene adipate terephthalate (PBAT); Thermoplastic starch (TPS) as a biodegradable natural polymer material; It relates to a biodegradable polymer composition for manufacturing a soft film containing 2,3-epoxypropyl methacrylate as a binder and EBS (Ethylene bis-stearamide) as a dispersant.

In response to recent changes in the government's environmental regulation policies, interest in the use of eco-friendly materials is rapidly increasing in the packaging-related distribution industry. Demand for reducing the proportion of plastic packaging containers, which are considered the main cause of environmental pollution, producing containers that are easy to recycle, and packaging paper using paper continues to increase.

Meanwhile, the use of biodegradable materials has maintained rapid growth over the past few years due to their environmental friendliness. The use of these substances is widespread and is being applied to various types of products.

Plastics are divided into thermoplastic resins and thermosetting resins. Thermoplastic resins become flexible when a certain temperature is applied, making them easy to mold and process and suitable for mass production. However, it is soluble in solvents, and its heat resistance, chemical resistance, and mechanical strength are inferior to thermosetting. These include vinyl (PVC), ABS, PP, PE, PS, PC, etc. Once thermosetting resin is hardened, it becomes hard when heat is applied, is insoluble in any solvent, and its chemical structure changes. These include epoxy, polyurethane, and meramine.

Vinyl (PVC) is a thermoplastic resin that has had a great impact on the screen printing industry in the past. It has excellent acid resistance, alkali resistance, and water resistance, is transparent, can be freely colored, and has good processability. There are two types: hard and soft. Hard PVC is made of PVC in its original state or by adding about 5% of plasticizer and is hard. Uses include water pipes, plumbing, industrial materials, building materials, signboards, and food containers. Soft PVC has a flexible feel because 30-50% of plasticizer is added. Although the properties of PVC in its original state are deteriorated, flexible thin films or sheets can be freely manufactured, so it is used in large quantities for artificial leather and greenhouses. It occupies such an important place in our lives that its uses are so extensive that it is impossible to list them all.

Republic of Korea Patent Publication No. 10-2023-0052808

The present invention was prepared in consideration of the above points, and aims to provide a biodegradable soft film composition that can be biodegraded even in general soil using biodegradable polymers and has excellent physical properties.

In order to solve the above-described problem, according to one embodiment of the present invention, polybutylene adipate terephthalate (PBAT) as a biodegradable polymer; Thermoplastic starch (TPS) as a biodegradable natural polymer material; A biodegradable polymer composition for manufacturing a soft film containing 2,3-epoxypropyl methacrylate as a binder and EBS (Ethylene bis-stearamide) as a dispersant is provided.

The polybutylene adipate terephthalate (PBAT) and thermoplastic starch (TPS) are mixed at a ratio of 70 to 90% by weight and 10 to 30% by weight, and are preferably mixed at a weight ratio of 8:2. You can.

The binder and dispersant are mixed at 0.1 to 5% by weight based on the total weight of the PBAT and TPS mixture, and are preferably mixed at 1% by weight based on the total weight of the PBAT and TPS mixture.

In the case of the thermoplastic starch (TPS), the moisture content is less than 600 ppm (less than 0.06%), and may preferably be 100 to 600 ppm.

The composition is characterized in that it further contains calcium carbonate or talc as a filler.

The filler is mixed in an amount of 5 to 15% by weight based on the total weight of the PBAT and TPS mixture, and is preferably mixed in an amount of 10% by weight based on the total weight of the PBAT and TPS mixture.

The composition may further include dioctyl sebacate or polydiethyl hexyl glycol adipate as a plasticizer.

The plasticizer is mixed in an amount of 1 to 10% by weight based on the total weight of the PBAT and TPS mixture, and is preferably mixed in an amount of 5% by weight based on the total weight of the PBAT and TPS mixture.

The biodegradable polymer composition for producing a soft film containing thermoplastic starch of the present invention is biodegradable even in general soil by using a biodegradable polymer, and has excellent physical properties.

Figure 1 is a diagram showing changes in film color depending on filler content and type.
Figure 2 is an SEM image showing the results of PLA morphology analysis according to compatibilizer content.

Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings. In describing embodiments of the present invention, if it is determined that a detailed description of a related known function or configuration may obscure the gist of the present invention, the detailed description will be omitted. In addition, the terms described below are terms defined in consideration of functions in the present invention, and may vary depending on the intention or custom of the user or operator. Therefore, the definition should be made based on the contents throughout this specification.

<Example 1>

1. Compounding using competitive thermoplastic starch products, manufacturing soft film and documenting physical properties

The compound was manufactured according to the mixing ratio of thermoplastic starch and PBAT. Compounds were manufactured according to TPS content (20, 30, 40, 50, 60%) and films were produced using a 500L BOBBIN WINDER film extruder, and specimens were tested using hot press QM900A, universal material testing machine QM100S, and tear strength tester LM- The physical properties were evaluated using 137 equipment.

No. TPS(%) Tensile strength (MPa) Elongation (%) Tear strength (N/mm) note One 20 >35 500-550 > 100 2 30 >35 550-600 > 100 3 40 >25 500-550 > 100 4 50 > 10 150-200 >80 5 60 N/D N/D N/D Fabric molding

It was confirmed that as the TPS content increases, the tensile strength and tear strength decrease, and the elongation improves up to 40% of TPS and then drops from 50%. When applying high TPS content up to 60%, film processability was significantly reduced.

2. Evaluation and selection of starch-based soft film color control filler applicability

(1) Evaluation of applicability of calcium carbonate (CaCO ₃ ) and talc filler

1t (size 1micron) CaCO ₃ from Chungmu Chemical and Talc (KC2000, 5micron) from Coats Co., Ltd. were selected as fillers, and the compound was manufactured by adjusting the content of PBAT according to the filler content.

While fixing the TPS content at 30% and changing the calcium carbonate and talc content, specimens were produced for each test item using compound manufacturing and a 500L BOBBIN WINDER film extruder, and film physical property analysis was conducted.

No. CaCO ₃ (%) Talc(%) Tensile strength (MPa) Elongation (%) Tear strength (N/mm) One 5 - >35 550-600 > 100 2 10 - >35 500-550 > 100 3 20 - >25 350-400 >80 4 30 - > 10 100-150 >60 5 - 10 >35 400-450 >80 6 - 20 >30 300-350 >70

In the case of calcium carbonate, it was confirmed that the tensile strength and elongation decreased when the content was over 30%, and in the case of talc, it was confirmed that the tensile strength and elongation decreased when the content was over 20%.

In conclusion, it is desirable to use filler at a content of 10%, and if the mixing ratio of TPS and PBAT does not maintain a certain level, tensile strength and elongation may decrease. It was confirmed that mechanical properties such as tear strength decreased.

(2) Cellulose filler applicability evaluation

In the case of cellulose filler, the physical properties were evaluated in advance by applying it to PLA, a biodegradable resin with excellent rigidity, to evaluate its influence as a reinforcing material in terms of mechanical strength and heat resistance.

Applicability evaluation by content was conducted using cellulose powder (D50 7㎛, self-produced) as a filler in PLA.

A 45mm twin-screw extruder (L/D=30/1) was used to manufacture the compound, and the processing conditions were discharge speed of 800rpm, feeding speed of 30rpm, temperature condition of 170~200℃, water cooling, and pelletizing with vibrator at 0.4rpm. . In order to test the basic properties of the produced compound, specimens for each test item were produced using an injection molding machine 110MMC and a film extruder 500L BOBBIN WINDER. For each test, hot press QM900A, universal material testing machine QM100S, and tear strength tester LM-137 equipment were used. It was utilized.

PLA cellulose Tear strength
(N/mm) impact strength
(kgf·cm/cm) heat resistance
(℃) tensile strength
(MPa) 100% 0% 63 5.0 55 450 95% 5% 62 5.5 56 440 90% 10% 62 5.8 57 432 80% 20% 61 6.2 57 430 70% 30% 59 6.3 58 420

It was confirmed that the surface of the strand was smooth during compound extrusion, resulting in less surface moisture due to water cooling, and the degree of dispersion of cellulose added by applying a certain pressure and temperature to the raw material using a hot press was confirmed. It was confirmed that as the added cellulose content increased, the degree of dispersion in the raw material decreased.

The tear strength and tear strength analyzed using injection and film specimens were the most improved when adding 5% of cellulose, but the impact strength slightly improved as the content increased. In addition, the heat resistance temperature increased with the addition of cellulose, and the heat resistance increased when cellulose was added as a reinforcing material.

In general, when checking the change in physical properties according to the amount of cellulose added, it was confirmed that the optimal condition for strength improvement was when less than 5% of cellulose was added as a reinforcing material. However, in the case of cellulose powder, the price is 5 to 10 times higher than fillers such as CaCO ₃ and Talc, so it is necessary to consider the cost when applying.

(3) Film color evaluation by filler type

After fixing the thermoplastic starch at 20%, color evaluation was performed by changing the ratios of cellulose, calcium carbonate, and talc as shown in the table below.

The compound used a 45mm twin-screw extruder (L/D=30/1), and the processing conditions were discharge speed of 800rpm, feeding speed of 30rpm, temperature condition of 150~160℃, water cooling, and pelletizing with vibrator at 0.4rpm. Film specimens were produced from the produced compounds using a 500L BOBBIN WINDER film extruder, and the colors of each film were compared.

No. cellulose CaCO ₃ Talc TPS PBAT One - - - 20% 80% 2 5% - - 75% 3 10% - - 70% 4 - 5% - 75% 5 - 15% - 65% 6 - - 5% 75% 7 - - 15% 65%

Referring to Figure 1, the color of the film became darker brown as the cellulose content increased, and the difference in color due to changes in the content of calcium carbonate and talc was minimal.

The factor affecting film color appears to be more largely due to low-molecular-weight organic fillers such as cellulose than to inorganic fillers such as calcium carbonate and talc, which means that heat damage caused by extrusion and film processing affects organic fillers more than inorganic fillers. It appears that

3. Evaluation and selection of applicability of starch-based soft film property improvement additives

Prior to applying additives to improve the physical properties of starch-based biodegradable composite materials, the effect of improving physical properties was confirmed by applying additives to biodegradable resins based on the evaluation results for each type of biodegradable plastic resin.

(1) Evaluation of applicability of nucleating agent

Compound manufacturing and applicability evaluation were conducted by varying the content of nucleating agent (DuPont LAK-301) in PLA, a biodegradable plastic resin.

A 45mm twin-screw extruder (L/D=30/1) was used to manufacture the compound, and the processing conditions were discharge speed of 800rpm, feeding speed of 30rpm, temperature condition of 200~210℃, water cooling, and pelletizing with vibrator at 0.4rpm. . In order to test the basic properties of the produced compound, specimens for each test item were produced using an injection molding machine 110MMC and a film extruder 500L BOBBIN WINDER. For each test, hot press QM900A, universal material testing machine QM100S, and tear strength tester LM-137 equipment were used. It was utilized.

PLA Nucleus Tear strength
(N/mm) impact strength
(kgf·cm/cm) heat resistance
(℃) tensile strength
(MPa) 100% 0% 63 5.0 55 450 99% One% 63 5.0 60 450 98% 2% 63 5.2 63 445 97% 3% 62 5.4 65 440 96% 4% 62 5.4 65 440 95% 5% 61 6.5 65 420

There was no significant difference in the surface of the strand depending on the nucleating agent content, but the surface condition was somewhat rough when 5% was added. When an external force was applied to the strand, it was destroyed when continuous force was applied until 4% of the nucleating agent was added, and when 5% was added, it was confirmed that it was destroyed more easily than before. In addition, when the strand was immersed in water at approximately 70°C, it was confirmed that the degree of bending and time required decreased as the nucleating agent content increased.

The tear strength and tensile strength analyzed using injection and film specimens were confirmed to decrease as the nucleating agent content increased, and the decrease was not wide at 20N/cm and 30MPa. In addition, during a simple physical property check, the phenomenon of the strand bending easily when immersed in water at about 70℃ can be related to heat resistance. The heat resistance temperature according to the content of 1-5% of the nucleating agent is shown to be below 65℃, and it bends at water temperatures above that. Changes were observed.

Therefore, considering the improvement in heat resistance and changes in physical properties of biodegradable plastic, it was confirmed that the optimal condition was when 3% or less of nucleating agent was used.

(2) Evaluation of applicability of compatibilizer

Compound production and applicability evaluation were conducted by varying the content of compatibilizer (BASF's ADR-4468) in PLA, a biodegradable plastic resin.

A 45mm twin-screw extruder (L/D=30/1) was used to manufacture the compound, and the processing conditions were discharge speed of 800rpm, feeding speed of 30rpm, temperature condition of 170~200℃, water cooling, and pelletizing with vibrator at 0.4rpm. . In order to test the basic properties of the produced compound, specimens for each test item were produced using an injection molding machine 110MMC and a film extruder 500L BOBBIN WINDER. For each test, hot press QM900A, universal material testing machine QM100S, and tear strength tester LM-137 equipment were used. It was utilized.

PLA compatibilizer Tear strength
(N/mm) impact strength
(kgf·cm/cm) heat resistance
(℃) tensile strength
(MPa) 100% 0% 63 5.0 55 450 99.9% 0.2% 68 5.4 55 480 99.6% 0.4% 72 5.8 55 490 99.4% 0.6% 72 5.8 55 494 99.0% 1.0% 72 6.0 55 498 98.0% 2.0% 72 6.0 55 495

The tear strength, impact strength, and tensile strength analyzed using injection and film specimens increased with the increase in compatibilizer content, and it was confirmed that there was no change in heat resistance. Through this, it was confirmed that the overall physical properties were strengthened when adding a compatibilizer without affecting heat resistance.

The degree of compatibilization according to the addition of the compatibilizer was confirmed through SEM measurement. Based on the physical property measurement data, the morphology of PLA with 0%, 0.2%, and 1% of compatibilizer was measured using SEM at the Korea University of Technology and Technology Common Equipment Support Center.

Referring to Figure 2, when considering the reinforcement of physical properties and unit cost according to compatibility, it was confirmed that the optimal condition was to add at least 1% of a compatibilizer.

4. Conditions for processing soft films using starch-based biodegradable composite materials

In addition to an overseas thermoplastic starch product (BiologiQ's NuplastiQ), Agrana's TPS was additionally obtained, a compound was manufactured using thermoplastic starch (TPS) and PBAT at a mixing ratio of 2:8, and film processing and physical property evaluation were performed.

division NuplastiQ Agrana TPS Tensile strength (MPa) 27 / 22 28 / 19 Elongation (%) 758 / 763 654 / 643 Tear strength (N/mm) 86 / 79 102 / 104

In the case of overseas thermoplastic starch products, it was confirmed that Agrana's TPS had higher tensile strength and tear strength than BiologiQ's TPS.

In addition to the biodegradable composite material mix, 1% each of the binder 2,3-epoxypropyl methacrylate and the dispersant Ethylene bis-stearamide (EBS) were added relative to the total weight of the TPS and PBAT mixture, and compound manufacturing, film processing, and physical property evaluation were performed.

division NuplastiQ 20% NuplastiQ 20% + additives Tensile strength (MPa) 27 / 22 38 / 33 Elongation (%) 758 / 763 599 / 644 Tear strength (N/mm) 86 / 79 140 / 117

As a result of adding binder and dispersant to the biodegradable composite material, it was confirmed that the tensile strength and tear strength increased significantly. However, it was confirmed that the elongation decreased.

5. Comparison of physical properties according to moisture content of thermoplastic starch

To control the moisture contained in the thermoplastic starch, dehumidifying and drying was performed for more than 4 hours, and the compound was composed of 1% binder and 1% dispersant based on the total weight of TPS and PBAT 2:8 mixed and compounding extrusion was performed. The moisture content of TPS before dehumidification is 1,300 to 1,500 ppm (0.13 to 0.15%), and the moisture content after dehumidification is less than 600 ppm (less than 0.06%).

Film processing and physical property evaluation were performed using a film extruder using a compound. Changes in physical properties before and after dehumidification were evaluated using a dehumidifying dryer.

division TPS 20% (before dehumidification) TPS 20% (before dehumidification) Tensile strength (MPa) 28 / 20 33 / 31 Elongation (%) 468 / 697 511 / 778 Tear strength (N/mm) 84 / 82 108 / 96 Moisture content (ppm) 3,620 1,560

As a result of evaluating starch-based composite materials, it was confirmed that when the moisture content of TPS is reduced, mechanical properties such as tensile strength, elongation, and tear strength all increase, and the moisture content decreases by more than half with dehumidification and drying. there is.

6. Physical property evaluation according to filler and plasticizer mixing

Thermoplastic starch (TPS) and PBAT were added to a mixing ratio of 2:8, and the binder 2,3-epoxypropyl methacrylate and the dispersant Ethylene bis-stearamide (EBS) were added at 1% each based on the TPS and PBAT mixture, resulting in an increase in elongation. showed a decreasing trend.

Accordingly, in order to find an additive that can improve elongation, the present inventor prepared a compound by mixing filler and plasticizer, and proceeded with film processing and physical property evaluation.

For each additive, 10% of filler and 5% of plasticizer were added based on the total weight of thermoplastic starch (TPS) and PBAT mixture.

No. filler plasticizer Elongation (%) Tensile strength (MPa) One CaCO ₃ Di-2-ethylhexyl sebacate 748 / 752 37 / 34 2 CaCO ₃ (Polydi(2-ethylhexyl)glycoladipate 784 / 796 42 / 40 3 Talc Di-2-ethylhexyl sebacate 738 / 748 37 / 35 4 Talc (Polydi(2-ethylhexyl)glycoladipate 764 / 778 40 / 39

It was confirmed that the highest elongation and tensile strength were achieved when calcium carbonate was used as a filler and polydiethylhexyl glycol adipate (PDGAP) was used as a plasticizer.

In the case of filler, higher elongation and tensile strength were shown when calcium carbonate was used rather than talc, and in the case of plasticizer, PDGAP was added compared to when dioctyl sebacate [dioctyl sebacate = di(2-ethylhexyl sebacate)] was used. It was confirmed that high elongation and tensile strength were observed.

As such, a person skilled in the art will understand that the technical configuration of the present invention described above can be implemented in other specific forms without changing the technical idea or essential features of the present invention.

Therefore, the embodiments described above should be understood in all respects as illustrative and not restrictive, and the scope of the present invention is indicated by the claims described later rather than the detailed description above, and the meaning and scope of the claims and their All changes or modified forms derived from the equivalent concept should be construed as falling within the scope of the present invention.

Claims (8)

Polybutylene adipate terephthalate (PBAT) as a biodegradable polymer;
Thermoplastic starch (TPS) as a biodegradable natural polymer material;
2,3-epoxypropyl methacrylate as a binder;
EBS (Ethylene bis-stearamide) as a dispersant;
Contains calcium carbonate as a filler and polydiethylhexylglycol adipate as a plasticizer,
The moisture content of the TPS is less than 600 ppm,
A biodegradable polymer composition for manufacturing a soft film, characterized in that the PBAT and TPS are mixed at a ratio of 80% by weight and 20% by weight.
delete According to paragraph 1,
A biodegradable polymer composition for manufacturing a soft film, characterized in that the binder and dispersant are mixed at 0.1 to 5% by weight based on the total weight of the PBAT and TPS mixture.
delete delete According to paragraph 1,
A biodegradable polymer composition for manufacturing a soft film, characterized in that the filler is mixed in an amount of 5 to 15% by weight based on the total weight of the PBAT and TPS mixture.
delete According to paragraph 1,
A biodegradable polymer composition for manufacturing a soft film, characterized in that the plasticizer is mixed in an amount of 1 to 10% by weight based on the total weight of the PBAT and TPS mixture.