Biodegradable plastic resin composition, molded article using same, and molded article manufacturing method

Abstract

The present invention relates to a biodegradable plastic resin composition, a molded article using the same, and a molded article manufacturing method. The biodegradable plastic resin composition according to an embodiment of the present invention comprises a biodegradable plastic; and a nanocellulose additive, which can provide a biodegradable plastic molded article that improves low crystallinity and low durability of the biodegradable plastic and improves moldability.

Description

Technical Field

[0001] The present invention relates to a biodegradable plastic resin composition, a molded product using the same, and a method for producing the molded product. Background Art

[0002] Plastics have replaced existing materials such as glass, metal, wood and paper, and are widely used and greatly facilitate daily life. Plastics have a significant impact on modern people's daily life and industrial development, but they have the disadvantage of not being able to decompose naturally, and it takes hundreds of years to completely decompose. This characteristic causes environmental pollution, making plastic waste management a major problem worldwide. Currently, there are methods such as landfill and incineration, but these methods cannot cause decay and will produce harmful gases, causing secondary pollution.

[0003] In order to overcome the above problems, biodegradable plastics are a solution to environmental pollution that people are concerned about because they can be decomposed quickly and naturally without any impact on the environment. The main principle of biodegradable plastics is that plastic materials are decomposed into low molecules under the action of enzymes secreted by microorganisms, and the microorganisms absorb these low molecules and metabolize them, and finally return to nature.

[0004] Biodegradable plastics are commercially replacing plastics due to environmental concerns, however biodegradable plastics have poor formability in molding processes such as extrusion and injection molding for producing plastic products, and their usability as a single polymer is limited.

[0005] The content of the above background technology is what the inventor mastered or learned in the process of developing the present invention, and should not be understood as necessarily being the general known technology disclosed before applying for the present invention. Summary of the invention

[0006] Technical issues to be solved

[0007] The present invention aims to provide a biodegradable plastic resin composition having improved moldability to solve the above problems.

[0008] Specifically, the present invention aims to provide a biodegradable plastic molded product which improves moldability by adding nanocellulose to compensate for the low crystallinity and low durability of the biodegradable plastic without any other additives.

[0009] The technical problems to be solved by this embodiment are not limited to the above-mentioned topics, and other topics not mentioned will be clearly understood by ordinary technicians in this field through the following description.

[0010] Technical methods to solve problems

[0011] A biodegradable plastic resin composition according to an embodiment of the present invention includes biodegradable plastic; and a nanocellulose additive.

[0012] According to one embodiment, the biodegradable plastic includes at least one selected from the group consisting of polylactic acid (PLA), polybutyleneadipate terephthalate (PBAT), polybutylene succinate (PBS), polycaprolactone (PCL), polyglycolic acid (PGA), poly-3-hydroxybutyrate (P3HB) and polyhydroxyalkanoate (PHA).

[0013] According to one embodiment, the biodegradable plastic accounts for more than 90 wt % of the biodegradable plastic resin composition.

[0014] According to one embodiment, the nanocellulose additive includes cellulose nanocrystals (CNC), cellulose nanofibers (CNF), or both.

[0015] According to one embodiment, the length of the cellulose nanocrystal is 1 nm to 900 nm, and the diameter of the cellulose nanofiber is 1 nm to 90 nm.

[0016] According to one embodiment, the weight ratio of the cellulose nanocrystals to the cellulose nanofibers is 1:0.5 to 1:0.1.

[0017] According to one embodiment, the nanocellulose additive is 0.1 wt % to 10 wt % in the biodegradable plastic resin composition.

[0018] According to one embodiment, the nanocellulose additive is less than 1000 ppm in the biodegradable plastic resin composition.

[0019] According to one embodiment, the nanocellulose additive is in powder form or water-dispersible gel form.

[0020] According to one embodiment, the water-dispersible gel nanocellulose additive is 0.1 wt % to 5 wt % in the biodegradable plastic resin composition.

[0021] According to one embodiment, the biodegradability of the biodegradable plastic resin composition is more than 90% based on 180 days, and the formability of the biodegradable plastic resin composition is that the stretching ratio in the MD or TD direction is 3.1 to 3.5 times, or the difference between the stretching ratios in the MD and TD directions is less than 0.2 times.

[0022] The biodegradable plastic molded article according to an embodiment of the present invention is formed by the biodegradable plastic resin composition according to the present invention alone, or by adding the composition as a master batch.

[0023] According to an embodiment of the present invention, a method for manufacturing a biodegradable plastic molded product comprises the following steps: preparing a nanocellulose additive; adding the nanocellulose additive to a biodegradable plastic to form a biodegradable plastic resin composition; and using the composition to manufacture a molded product.

[0024] According to one embodiment, the step of forming the biodegradable plastic resin composition is to mix the nanocellulose additive with the biodegradable plastic by solvent mixing or melt mixing.

[0025] According to one embodiment, the nanocellulose additive is used to prepare a high-content masterbatch by a primary dispersion in the biodegradable plastic, and then the masterbatch is dispersed again with the polymer.

[0026] According to one embodiment, the step of forming the molded product is performed by injection molding, extrusion molding, blow molding or casting molding.

[0027] Effects of the Invention

[0028] The present invention can provide a biodegradable plastic resin composition having improved moldability.

[0029] Specifically, the present invention can provide a biodegradable plastic molded product which improves moldability by adding nanocellulose to compensate for the low crystallinity and low durability of the biodegradable plastic without any other additives. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a photograph of a film prepared according to a comparative example of the present invention.

[0031] Figure 2 is a photograph of a thin film prepared according to an embodiment of the present invention. DETAILED DESCRIPTION

[0032] Below, the exemplary embodiments will be described in detail with reference to the accompanying drawings. However, various changes can be made to the exemplary embodiments. In this article, the present disclosure is not limited to the exemplary embodiments. The exemplary embodiments should be understood to include all changes made within the concept and technical scope of the present disclosure, and their equivalents and even their substitutes.

[0033] The terms used in the embodiments are only used to illustrate specific embodiments and are not used to limit the scope. In the absence of special instructions in the content, a single expression includes multiple meanings. In this specification, the terms "including" or "having" are used to express the existence of features, numbers, steps, operations, constituent elements, accessories or combinations thereof recorded in the specification, and do not exclude the possibility of the existence or additional addition of one or more other features, numbers, steps, operations, constituent elements, accessories or combinations thereof.

[0034] In the absence of other definitions, all terms, including technical or scientific terms used herein, have the common meanings understood by ordinary technicians in the field to which the examples belong. Commonly used terms as defined in dictionaries should be understood as the meanings in the relevant technical content, and should not be interpreted as idealized or overly formalized meanings if they are not clearly defined in this specification.

[0035] In the process of describing the examples with reference to the accompanying drawings, the same parts use the same figure numbers, and repeated descriptions are omitted. In the process of describing the example embodiments, when it is judged that the specific description of the relevant known structure or function will cause unnecessary confusion to the present disclosure, its specific description is omitted. In addition, when describing the parts of the example embodiments, the terms such as first, second, A, B, (a), (b) can be used. These terms are only used to distinguish a part from other parts, and are not used to limit the nature, order or sequence of the corresponding parts. When describing that a part is "connected", "coupled" or "attached" to another part, it should be understood that a part can be directly connected or attached to another part, and an intermediate part can also be "connected", "coupled" or "attached" to the part.

[0036] When a constituent element has a common function with a constituent element of a certain embodiment, the same name is used to describe it in other embodiments. The description of a certain embodiment can be applied to other embodiments without mentioning a counterexample, and the specific description of the repeated content can be omitted.

[0037] A biodegradable plastic resin composition according to an embodiment of the present invention includes biodegradable plastic and a nanocellulose additive.

[0038] The biodegradable plastic resin composition according to the present invention can solve the environmental problems caused by existing plastics by using biodegradable plastics, and can improve the low moldability problem of biodegradable plastics due to their low crystallinity and low durability by adding nanocellulose additives.

[0039] According to one embodiment, the biodegradable plastic includes at least one selected from the group consisting of polylactic acid (PLA), polybutyleneadipate terephthalate (PBAT), polybutylene succinate (PBS), polycaprolactone (PCL), polyglycolic acid (PGA), poly-3-hydroxybutyrate (P3HB) and polyhydroxyalkanoate (PHA).

[0040] According to one embodiment, biodegradable plastic is an environmentally friendly resin that can be decomposed by bacteria or organisms. Polylactic acid is the most common biodegradable material made from plant materials such as corn or starch, and is used for food containers because of its low production cost and does not contain harmful substances such as environmental hormones or heavy metals. The polylactic acid can be at least one of the groups selected from L-isomers, D-isomers and L, D-isomers. According to one embodiment, polybutylene adipate terephthalate and polybutylene succinate are made by materials such as butanediol naturally occurring in synthetic petroleum raw materials, although more expensive than polylactic acid, but more heat-resistant and flexible, and do not require special conditions to obtain biodegradation in soil.

[0041] According to one embodiment, the biodegradable plastic accounts for more than 90 wt % of the biodegradable plastic resin composition.

[0042] According to one embodiment, when the content of the biodegradable plastic is less than 90% by weight, the content of the nanocellulose is 10% by weight or more, which may cause agglomeration and reduce injection moldability. When the content of the biodegradable plastic is within the above range, a biodegradable plastic resin composition with stable biodegradability and excellent moldability can be formed, and its content can be appropriately adjusted according to different molding methods such as spinning, injection, and extrusion.

[0043] According to one embodiment, the nanocellulose additive includes cellulose nanocrystals (CNC), cellulose nanofibers (CNF), or both.

[0044] According to one embodiment, nanocellulose is a biodegradable reinforcing agent that can enhance the physical properties that are insufficient in biodegradable plastics, and can also solve the problems existing in reinforcing agents made of existing inorganic materials. In addition, nanocellulose can be biodegraded and thermally decomposed, especially when compounded with biodegradable plastics such as PLA, PBAT, PBS and PHA, it can be well decomposed, and the composite material containing the above materials can be decomposed by microorganisms together with the matrix when landfilled.

[0045] According to an embodiment, nanocellulose is divided into cellulose nanocrystals and cellulose nanofibers. Nanocrystals are obtained by chemical treatment such as acid hydrolysis, cellulolytic enzymes and ionic liquids, while nanofibers are usually prepared by mechanical treatment. Nanocrystals have a simpler production process than nanofibers and have lower energy costs, but have the disadvantage of low yield, which can be solved by using nanocrystals and nanofibers at the same time.

[0046] According to one embodiment, the length of the cellulose nanocrystal is 1 nm to 900 nm, and the diameter of the cellulose nanofiber is 1 nm to 90 nm.

[0047] According to one embodiment, the length of the cellulose nanocrystal in any direction may be 1 nm to 900 nm, i.e., several nm to several hundred nm. If it is not within the above range, the dispersibility will be reduced and the problem of improving the formability will not be achieved. If the nanocrystal is spherical, the size of the nanocrystal may be the diameter, and if it is not spherical, it may be the longest length.

[0048] According to an embodiment, the diameter of the cellulose nanofibers may be 1 nm to 90 nm, that is, several nm to tens of nm. If the diameter of the nanofibers exceeds tens of nm, they cannot be fully nanofiberized, and the cohesion and dispersion between the fibers are reduced, and the formability cannot be improved.

[0049] According to one embodiment, the weight ratio of the cellulose nanocrystals to the cellulose nanofibers is 1:0.5 to 1:0.1.

[0050] According to one embodiment, when the weight ratio of cellulose nanocrystals to cellulose nanofibers is within the above range, by combining spherical and fibrous cellulose particles, a biodegradable plastic resin composition with stable biodegradability and excellent moldability can be formed with the advantage of improving moldability with a small amount of addition.

[0051] According to one embodiment, the nanocellulose additive is 0.1 wt % to 10 wt % in the biodegradable plastic resin composition.

[0052] According to one embodiment, the nanocellulose additive is preferably 0.1 wt% to 5 wt%, more preferably 1 wt% to 5 wt%. If the content of the nanocellulose additive exceeds 10 wt%, the mechanical properties or transparency may be deteriorated.

[0053] According to one embodiment, the nanocellulose additive is less than 1000 ppm in the biodegradable plastic resin composition.

[0054] According to one embodiment, the nanocellulose additive is preferably 10 ppm to 1000 ppm, more preferably 10 ppm to 500 ppm.

[0055] According to one embodiment, when the content of the added nanocellulose additive is within the above range, low crystallinity and low durability of the plastic resin composition can be improved, ensuring moldability.

[0056] According to one embodiment, the nanocellulose additive may be in powder form or water-dispersible gel form.

[0057] According to one embodiment, the nanocellulose additive may be a suspension of nanocellulose that has become fine in a water-dispersed state and used in the form of a water-dispersed gel, or may be used in the form of a powder by drying fine fibers.

[0058] According to one embodiment, the water-dispersible gel nanocellulose additive is 0.1 wt % to 5 wt % in the biodegradable plastic resin composition.

[0059] According to one embodiment, preferably, the water-dispersible gel nanocellulose additive is prepared into a masterbatch for use.

[0060] According to one embodiment, the content of the water-dispersible gel nanocellulose additive is preferably 0.1 wt% to 2.5 wt%. If the content of the water-dispersible gel nanocellulose additive exceeds 5 wt%, the miscibility with the hydrophobic polymer will be reduced due to the high water content, or the water cannot be effectively removed during the mixing process with the polymer, thereby reducing the physical properties and formability.

[0061] According to one embodiment, the biodegradability of the biodegradable plastic resin composition is more than 90% based on 180 days, and the formability of the biodegradable plastic resin composition is that the stretching ratio in the MD or TD direction is 3.1 to 3.5 times, or the difference between the stretching ratios in the MD and TD directions is less than 0.2 times.

[0062] According to international standards, plastics are considered biodegradable only when they eventually decompose. There are many ways to measure biodegradability, the most widely used of which is the ISO 14855 test method. The ISO 14855 test method measures the amount of carbon dioxide produced by measuring the aerobic biodegradability and disintegration of plastic materials under controlled composting conditions.

[0063] According to one embodiment, the biodegradable plastic resin composition exhibits biodegradability with more than 90% of organic carbon converted into inorganic carbon within 180 days. If the above biodegradability is not exhibited, it is difficult to be considered as biodegradable.

[0064] According to one embodiment, the formability can be confirmed by stretching the biodegradable plastic resin composition into a film. Generally, when the film is pulled out from a machine (roller), the direction of pulling out from the machine (roller) is the machine direction (MD), and the direction perpendicular to it is the vertical direction (TD). The formability can be confirmed by the extension multiples in the MD direction and the TD direction and their difference.

[0065] The biodegradable plastic molded product according to an embodiment of the present invention may be formed by the biodegradable plastic resin composition according to the present invention alone, or by adding the composition as a master batch.

[0066] According to one embodiment, the masterbatch is a granular raw material obtained by concentrating a plastic resin and an additive at a high concentration and then dispersing them. The biodegradable plastic resin composition can be masterbatched to form a molded product.

[0067] According to an embodiment of the present invention, a method for manufacturing a biodegradable plastic molded product comprises the following steps: preparing a nanocellulose additive; adding the nanocellulose additive to a biodegradable plastic to form a biodegradable plastic resin composition; and using the composition to manufacture a molded product.

[0068] According to one embodiment, the nanocellulose additive can be prepared in a powder form or a water-dispersible gel form.

[0069] According to one embodiment, the step of forming the biodegradable plastic resin composition is to mix the nanocellulose additive with the biodegradable plastic by solvent mixing or melt mixing.

[0070] According to one embodiment, the solvent mixing of the nanocellulose additive and the biodegradable plastic is performed using an organic solvent to achieve solvent mixing. In this case, powdered or water-dispersible gel nanocellulose can be mixed, but the water-dispersible gel nanocellulose is water-based and therefore may have poor dispersibility in organic solvents.

[0071] According to one embodiment, the nanocellulose additive and the biodegradable plastic can be melt-mixed. This method is an environmentally friendly mixing method that does not use organic solvents. Powdered or water-dispersible gel nanocellulose can be mixed. However, high-concentration water-dispersible gel nanocellulose must be used, and for cellulose nanofibers with low crystallinity, if the melt mixing is heated for too long, the nanocellulose may be thermally damaged.

[0072] According to one embodiment, the nanocellulose additive is used to be dispersed once in the biodegradable plastic to prepare a high-content masterbatch, and then the masterbatch is dispersed again with the polymer.

[0073] According to one embodiment, the polymer may be mixed with polybutylene adipate terephthalate (PBAT), polylactic acid (PLA), polyvinyl alcohol (PVA), etc. to prepare a masterbatch.

[0074] According to one embodiment, in order to improve the dispersibility of the nanocellulose additive in the polymer, it may be necessary to prepare it into a masterbatch and disperse the masterbatch again to form a molded product.

[0075] According to one embodiment, the step of forming the molded product is performed by injection molding, extrusion molding, blow molding or casting molding.

[0076] According to one embodiment, the molded article may have the form of a hard or soft plastic product.

[0077] Hereinafter, the present invention will be described in more detail by way of Examples and Comparative Examples.

[0078] However, the following examples are only used to illustrate the present invention and are not intended to limit the present invention.

[0079] Example

[0080] The biodegradable plastic resin composition was prepared by adding 1 wt % of cellulose nanocrystals (CNC) to 99 wt % of polybutylene adipate terephthalate (PBAT) and melt mixing at 150° C. by a twin-screw extruder.

[0081] Comparative Example

[0082] A biodegradable plastic composition prepared from 100 wt % polybutylene adipate terephthalate without any treatment was prepared.

[0083] Experimental example: Confirming formability

[0084] In order to confirm the moldability, the examples and comparative examples were extruded into films at 165° C. and a screw speed of 50 rpm using a T-die and the obtained products were confirmed.

[0085] Figure 1 is a photo of a film prepared according to a comparative example of the present invention, Figure 2 is a photo of a film prepared according to an embodiment of the present invention. Figure 1 as well as Figure 2 The comparative example used biodegradable plastic alone, and its formability was low, and the film shape could not be maintained at the extrusion port. On the contrary, the example added cellulose nanocrystals, and it can be confirmed that the film shape is intact, which shows that the example has excellent formability.

[0086] Although the present disclosure includes specific examples, it will be apparent to those skilled in the art that various changes in form and detail may be made in these examples without departing from the spirit and scope of the claims and their equivalents. Appropriate results may be obtained if the described techniques are performed in a different order, and / or if the constituent elements in the described systems, architectures, devices, or circuits are combined or combined in different forms, or replaced or substituted by other constituent elements or equivalents.

[0087] Therefore, the scope of the present invention is defined not by the specific contents of the specification but by the claims and their equivalents, and all variations within the scope of the claims and their equivalents should be construed as being included in the present disclosure.

Claims

1. A biodegradable plastic resin composition, characterized in that: include: biodegradable plastics; as well as Nanocellulose additives.

2. The biodegradable plastic resin composition according to claim 1, characterized in that: The biodegradable plastic includes at least one selected from the group consisting of polylactic acid (PLA), polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS), polycaprolactone (PCL), polyglycolic acid (PGA), poly-3-hydroxybutyrate (P3HB) and polyhydroxyalkanoate (PHA).

3. The biodegradable plastic resin composition according to claim 1, characterized in that: The biodegradable plastic accounts for 90% by weight or more of the biodegradable plastic resin composition.

4. The biodegradable plastic resin composition according to claim 1, characterized in that: The nanocellulose additive includes cellulose nanocrystals (CNC), cellulose nanofibers (CNF), or both.

5. The biodegradable plastic resin composition according to claim 4, characterized in that: The length of the cellulose nanocrystal is 1 nm to 900 nm, The diameter of the cellulose nanofibers is 1 nm to 90 nm.

6. The biodegradable plastic resin composition according to claim 4, characterized in that: The weight ratio of the cellulose nanocrystals to the cellulose nanofibers is 1:0.5 to 1:0.

1.

7. The biodegradable plastic resin composition according to claim 1, characterized in that: The nanocellulose additive is 0.1 wt% to 10 wt% in the biodegradable plastic resin composition.

8. The biodegradable plastic resin composition according to claim 1, characterized in that: The nanocellulose additive is less than 1000 ppm in the biodegradable plastic resin composition.

9. The biodegradable plastic resin composition according to claim 1, characterized in that: The nanocellulose additive is in powder form or water-dispersible gel form.

10. The biodegradable plastic resin composition according to claim 9, characterized in that: The water-dispersible gel nanocellulose additive is 0.1 wt % to 5 wt % in the biodegradable plastic resin composition.

11. The biodegradable plastic resin composition according to claim 1, characterized in that: The biodegradability of the biodegradable plastic resin composition is 90% or more based on 180 days. The biodegradable plastic resin composition has moldability such that the stretching ratio in the MD or TD direction is 3.1 to 3.5 times, or the difference between the stretching ratios in the MD and TD directions is 0.2 times or less.

12. A biodegradable plastic molded product, characterized in that: The biodegradable plastic resin composition according to claim 1 is formed alone, or the composition is added as a master batch.

13. A method for producing a biodegradable plastic molded product, characterized in that: The following steps are involved: preparing nanocellulose additives; adding the nanocellulose additive to a biodegradable plastic to form a biodegradable plastic resin composition; and The composition is used to produce a molded article.

14. The method for producing a biodegradable plastic molded product according to claim 13, characterized in that: The step of forming the biodegradable plastic resin composition is to mix the nanocellulose additive with the biodegradable plastic by solvent mixing or melt mixing.

15. The method for producing a biodegradable plastic molded product according to claim 13, characterized in that: The nanocellulose additive is used to prepare a high-content masterbatch by a primary dispersion in the biodegradable plastic, and then the masterbatch is dispersed again with the polymer.

16. The method for producing a biodegradable plastic molded product according to claim 13, characterized in that: The step of manufacturing the molded product is to manufacture it by injection molding, extrusion molding, blow molding or casting molding.

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