TW202206542A - Composition, biodegradable shaped article made therefrom, and method of manufacturing the biodegradable shaped article - Google Patents

Abstract

A composition of biodegradable shaped article comprising a polylactic acid, an organic nucleating agent and a cellulose nanofiber, wherein the organic nucleating agent accounts for more than or equal to 0.0 3 wt% of the total weight of the composition, and the cellulose nanofiber accounts for more than or equal to 0.1 wt% of the total weight of the composition. A biodegradable shaped article made from the aforementioned composition, wherein the composition is fluxed and made into pellets, these pellets are then heated and shaped into the shaped article. A method of manufacturing a biodegradable shaped article comprising steps of mixing a polylactic acid, an organic nucleating agent and a cellulose nanofiber and preparing a composition, wherein the organic nucleating agent accounts for 0.03 to 9 wt% of the total weight of the composition, and the cellulose nanofiber accounts for 0.1 to 15 wt%; fluxing the composition and making the same into pellets; heating the pellets to form into the shaped article.

Description

Composition, biodegradable molded body produced therefrom, and method for producing a biodegradable molded body

The present invention relates to a composition that can be used to prepare biodegradable shaped bodies, especially a composition comprising polylactic acid.

Traditional plastic products can be mass-produced quickly and are convenient and hygienic, so they are widely used in various products in daily life. However, they also cause environmental pollution problems due to one-time use and difficulty in decomposition. Recently, biodegradable materials have been developed, which are expected to replace traditional plastics and alleviate environmental pollution.

Polylactic acid is one such biodegradable material. However, the molded body obtained from polylactic acid is usually amorphous, has poor heat resistance, and is not suitable for use at a slightly higher temperature, so its use is greatly limited. In order to improve the heat resistance of a polylactic acid molded body, it is known to add a nucleating agent to polylactic acid to crystallize it during molding. However, while improving the crystallinity, the polylactic acid molded body also loses its original transparency, so the use is still limited. In addition, when some nucleating agents are used, the migration of nucleating agent molecules occurs, resulting in unstable product quality.

In view of the above, the present invention provides a composition which can be used as a heat-resistant and transparent biodegradable molded body.

The composition provided by the present invention comprises polylactic acid, an organic nucleating agent and cellulose nanofibers, wherein the organic nucleating agent accounts for more than 0.03 wt % of the total weight of the composition, and the cellulose nanofibers account for 0.1% of the total weight of the composition. wt % or more.

In an embodiment of the present invention, the above-mentioned organic nucleating agent accounts for 0.03-9 wt % of the total weight of the composition, and the cellulose nanofibers account for 0.1-15 wt % of the total weight of the composition.

In an embodiment of the present invention, the above-mentioned organic nucleating agent accounts for 0.05-3 wt % of the total weight of the composition, and the cellulose nanofibers account for 0.1-5 wt % of the total weight of the composition.

In an embodiment of the present invention, the above-mentioned cellulose nanofibers are modified cellulose nanofibers.

In an embodiment of the present invention, the above-mentioned cellulose nanofibers include a plurality of glucose monomers; the modified cellulose nanofibers are oxidized cellulose nanofibers, and at least part of the glucose monomers have carboxylic acids or carboxylate functional group.

In an embodiment of the present invention, the oxidized cellulose nanofibers are TEMPO oxidized cellulose nanofibers, and at least part of the glucose monomers have functional groups of sodium carboxylate or lithium carboxylate at C6 position.

In an embodiment of the present invention, the above-mentioned modified cellulose nanofibers include lactide, polylactic acid oligomer, or grafting of lactide and polylactic acid oligomer.

In an embodiment of the present invention, the above-mentioned organic nucleating agent is aliphatic carboxylic acid amides, aliphatic carboxylates, aliphatic alcohols, aliphatic carboxylate nucleating agents or a combination thereof .

The present invention also provides a biodegradable shaped body made from the aforementioned composition, wherein the composition is kneaded into a plurality of granules which are then heated and shaped into a shaped body.

In an embodiment of the present invention, the above-mentioned plurality of particles are further heated to form a sheet, and the sheet is heated to form a shaped body.

The present invention also provides a method for manufacturing a biodegradable shaped body, comprising the steps of: mixing polylactic acid, an organic nucleating agent and cellulose nanofibers and preparing a composition, wherein the organic nucleating agent accounts for 0.03-9% of the total weight of the composition. wt %, the cellulose nanofibers account for 0.1-15 wt % of the total weight of the composition; the composition is kneaded and formed into a plurality of particles; the particles are heated and formed into a shaped body.

In an embodiment of the present invention, the above-mentioned step of heating the particles and forming the shaped body further comprises heating the particles and forming the sheet, and heating the sheet and forming the shaped body.

In an embodiment of the present invention, the above-mentioned step of heating the particles to form a formed body further includes performing an injection molding process, a blister molding process, an injection blow molding process, a blown film molding process, and a casting method film forming process. A shaped body is formed.

Because the present invention adopts organic nucleating agent and cellulose nanofibers, in addition to assisting the crystallization of the formed body, the crystallization efficiency is improved and the crystallization time is shortened, thus helping to improve the crystallinity and heat resistance.

In order to make the above-mentioned and other objects, features and advantages of the present invention more obvious and easy to understand, the following specific embodiments are given and described in detail in conjunction with the accompanying drawings.

The present invention provides a composition which can be used to prepare a biodegradable shaped body which is heat-resistant and transparent.

The composition of the present invention includes a biodegradable polymer, a nucleating agent, and Cellulose Nanofiber (CNF). Suitable biodegradable polymers are, for example, aliphatic polyesters, aliphatic-aromatic polyester copolymers, polylactic acid-aliphatic polyester copolymers (CPLA, Polylactide aliphatic polyester copolymers). ). Suitable nucleating agents are organic nucleating agents.

In an embodiment of the present invention, the composition includes polylactic acid of aliphatic polyester, an organic nucleating agent, and cellulose nanofibers. The polylactic acid can be, for example, a polylactic acid product of NatureWorks. For example, the organic nucleating agent can be aliphatic carboxylic acid amide, aliphatic carboxylic acid salt, aliphatic alcohol, aliphatic carboxylic acid acid ester) and other nucleating agents. The amount of the organic nucleating agent in the embodiment of the present invention accounts for more than 0.03 wt % of the total weight of the composition, but preferably not more than 9 wt %, and may include one or more of the aforementioned types. The amount of the organic nucleating agent is preferably 0.05-3 wt % of the total weight of the composition.

The cellulose nanofibers of the embodiments of the present invention are modified cellulose nanofibers, and account for more than 0.1 wt % of the total weight of the composition, and preferably not more than 15 wt %. More preferably, the amount of cellulose nanofibers accounts for 0.1-5 wt% of the total weight of the composition. The modified cellulose nanofibers include oxidized cellulose nanofibers, and at least part of the glucose monomers of the cellulose have functional groups of carboxylic acid or carboxylate. Preferably, the oxidized cellulose nanofibers in the embodiment of the present invention are TEMPO oxidized cellulose nanofibers obtained by TEMPO oxidation, and at least part of the glucose monomers in the cellulose has sodium carboxylate or lithium carboxylate. functional group. In addition to oxidation, cellulose nanofibers can be modified by other modifications, such as introducing hydrophobicity and/or grafting on TEMPO oxidized cellulose nanofibers to improve their compatibility with polylactic acid. The sites of sex and/or grafting are, for example, functional groups such as carboxyl, carboxylate, and hydroxyl. For example, cellulose nanofibers can be treated with maleic anhydride grafted polyethylene, maleic anhydride grafted polylactic acid, and polystyrene as modifiers to improve their hydrophobicity; and/or with L-lactide, TEMPO cellulose nanofibers are treated with polylactic acid oligomers, etc.

Furthermore, depending on the needs of the manufacturing process or the scope of application, the composition of the embodiments of the present invention may further include other components such as heat stabilizers, colorants, antistatic agents, flame retardants, foaming agents, anti-UV stabilizers, anti-slip agents, etc. agents, plasticizers, inorganic fillers, antioxidants, lubricants, etc. After deducting the weight of organic nucleating agent, cellulose nanofibers and other components, the remaining weight is the weight of polylactic acid.

The composition of the present invention includes cellulose nanofibers, and the hydroxyl functional groups of the cellulose nanofibers and the organic nucleating agent are easy to form hydrogen bonds, so the cellulose nanofibers can grasp the molecules of the organic nucleating agent, and the cellulose nanofibers can easily form hydrogen bonds. Because the rice fiber is uniformly dispersed in the polylactic acid matrix, it forms a barrier, which helps to inhibit the migration of organic nucleating agents, helps crystallization, improves the crystallization efficiency, and shortens the crystallization time. Therefore, on the one hand, the degree of crystallinity can be improved and the heat resistance of the formed body can be improved, and on the other hand, the crystal particles that are too large and their adverse effects on transparency can be avoided.

The present invention also provides a biodegradable shaped body made from the aforementioned composition. The biodegradable shaped body is heat-resistant and transparent. In an embodiment of the present invention, as shown in FIG. 1 , manufacturing a biodegradable shaped body may include step S100 : mixing polylactic acid, an organic nucleating agent and cellulose nanofibers to prepare a composition, wherein the organic nucleating agent accounts for 0.03-9 wt % of the total weight of the composition, cellulose nanofibers account for 0.1-15 wt % of the total weight of the composition; and step S200: kneading the composition and forming a plurality of particles. These granules can be semi-finished products. After step S200, the semi-finished pellets can be further processed and formed into shaped bodies and/or final products.

The embodiment of the present invention further includes step S300: heating a plurality of particles to form a shaped body. The shaped body herein can be the final product, or it can be further processed to produce the final product. The processing can be injection molding, thermoforming, injection blown, film by blown, and film by casting, etc. But not limited to this. For example, a plurality of particles can be formed into a shaped body of a sheet, and then the sheet is heated and moulded to produce the final product.

Step S300 may further include procedures such as injection molding, blister molding, injection blow molding, film blowing, and casting film forming, and the particles in step S200 are formed into a molded body through the procedures.

The present invention also tests the crystallization rate, crystallinity, heat resistance, haze, etc. of the particles or formed bodies during or at the end of step S200 or S300.

The following examples illustrate the manufacturing method and testing method of the biodegradable shaped body according to the embodiment of the present invention.

Example:

1. Materials and Equipment (1) Polylactic acid (PLA): from Nature Works or Total Corbion. (2) Organic nucleating agent: selected from aliphatic carboxylic acid amides of ethylene bislauramide (Mitsubishi Chemical), aliphatic carboxylic acid salts of zinc stearate (Dainichi Chemical Industry), stearyl alcohol (Kao Japan) and pentanol (Tokyo Chemical Industry) of fatty alcohols. (3) Cellulose nanofibers: (3-1) TEMPO oxidized cellulose nanofibers, which can be purchased directly or prepared as follows: Using 2,2,6,6-tetramethylpiperidine-1-oxyl (2,2,6,6-tetramethylpiperidine-1-oxyl; TEMPO) as catalyst, sodium hypochlorite (NaOCl) as main oxidant, sodium chlorate (NaBr) is an activator that oxidizes hydroxyl groups of cellulose (from pulp (Chinese pulp) to carboxyl groups in an aqueous solution (deionized water) to prepare TEMPO oxidized cellulose nanofibers (TOCNs), and at least part of these The glucose monomer has a functional group of sodium carboxylate at the C6 position. Further, sodium carboxylate can be substituted into lithium carboxylate. (3-2) TOCN-g-PLA, which can be purchased directly or prepared as follows: (3-1) TEMPO oxidized cellulose nanofibers and L-lactide were dissolved in tetrahydrofuran (Tetrahydrofuran; THF), and L-lactide was ring-opened and then polymerized and grafted on TEMPO. The carboxyl groups of oxidized cellulose nanofibers were then polymerized with polylactic acid oligomers to increase the molecular weight and steric barriers of polylactic acid grafted on TEMPO oxidized cellulose nanofibers. (4) Other ingredients: L-lactide: Puralact® L (Total Corbion) for lactide grafting of TEMPO oxidized cellulose nanofibers. PLA oligomer: Futerro, PLA oligomer grafting for TEMPO oxidized cellulose nanofibers. (5) Twin Screw Mixer: LabTech Twin Screw Extruder, used in step S200. (6) Single-screw casting machine (Film casting): used in step S300. (7) Blister machine: used in step S300. (8) Thermal Differential Scanning Calorimeter: TA Instruments DSC 250, used to measure the crystallization rate and crystallinity. (9) Heat Deflection Temperature Instrument: Instron CEAST HV500 (ASTM D648), used to measure heat resistance (ie Heat Deflection Temperature (HDT)). (10) Haze meter: BYK Haze guard i (ASTM D1003), for measuring transparency.

2. Steps

Steps S100-S200: mixing 92-99.85% by weight of polylactic acid, 0.05-3% organic nucleating agent and 0.1-5% TOCN-g-PLA, and supplying them to a twin-screw chain mixer. The twin-screw chain mixer uniformly disperses the cellulose nanofibers in the polylactic acid polymer, melts and kneads them at a temperature of 160°C to 220°C, extrudes them into bundles, and then cuts them into multiple pellets. Examples are as follows (Examples 1 to 3).

Example 1: Polylactic acid (Ingeo 2003D (Nature Works)), TOCN-g-PLA and nucleating agent (stearyl alcohol (Kao Japan)) were mixed in the proportions of 96.5 wt%, 3 wt% and 0.5 wt%, using The twin-screw chain mixer uniformly disperses TOCN-g-PLA in the PLA polymer matrix, and the temperature is set between 160°C and 220°C. The resulting pellets were dewatered in an oven, the temperature was set to 70°C, and the water content was controlled to be 250 ppm or less.

Example 2: Polylactic acid (Ingeo 2003D (Nature Works)), TOCN-g-PLA and a nucleating agent (stearyl alcohol (Kao Japan)) were mixed at a ratio of 96 wt%, 3 wt% and 1 wt%. The subsequent steps are the same as those in the first embodiment.

Example 3: Polylactic acid (Ingeo 2003D (Nature Works)), TOCN-g-PLA and a nucleating agent (stearyl alcohol (Kao Japan)) were mixed at a ratio of 94 wt%, 3 wt% and 3 wt%. The subsequent steps are the same as those in the first embodiment.

Step S300: Heating a plurality of particles and forming a shaped body. Step S300 may further include a process of blister molding, which is exemplified as follows (Embodiment 4).

Embodiment four: get the particles after embodiment one, two or three drying, use single screw casting machine to prepare sheet (sheet). The sheet thickness is 0.5 mm. A labscale blister machine with upper and lower platen heaters was used, the temperature was set to 100°C, and the plates were heated for 30 seconds. Next, the plate was molded into the shape of the mold by air pressure and vacuum, and the mold temperature was set to 40°C.

3. Test method (A) Crystallinity and crystallization rate: Take the formed body in step S300 for testing, and measure its crystallinity and crystallization rate with a thermal differential scanning calorimeter. Crystallinity (%) = ΔH _m +ΔH _c /ΔH _f , where ΔH _m is the measured enthalpy of fusion (positive value), ΔH _c is the measured enthalpy of crystallization (negative value), and ΔH _f is Enthalpy of complete crystallization of polylactic acid (ΔH _f = 93 J/g). Crystallization rate refers to the crystallization half-life, ie the time required to reach 50% crystallinity. The crystallinity of the formed body in the embodiment of the present invention is preferably 25% to 50%, and the crystallization half-life is not more than 30 seconds. (B) Heat resistance (HDT): Tested with the molded body of step S300. The heat resistance of the molded body of the embodiment of the present invention is higher than 100°C. (C) Haze: the test was carried out with the molded body of step S300. The haze of the formed body of the embodiment of the present invention is less than 80%, and preferably less than 10%.

The measured crystallinity, heat resistance and haze of the molded body of Example 4 are shown in Table 1. Table I PLA (wt%) TOCN-g-PLA (wt%) Nucleating agent (wt%) Heat resistance (℃) Haze(%) Crystallinity (%) Example 1 96.5 3 0.5 110 2 39 Embodiment 2 96 3 1 112 3 41 Embodiment 3 94 3 3 115 5 43

The above embodiments are only examples, and the present invention does not limit the equipment used for manufacturing the formed body and the equipment used for testing.

Due to the mixed use of cellulose nanofibers in the embodiment of the present invention, it not only functions as a nucleating aid, but also forms hydrogen bonds with the organic nucleating agent, so the molecules of the organic nucleating agent are seized and the nucleation of the organic nucleating agent is inhibited. migration, thereby helping crystallization and improving crystallization efficiency and shortening crystallization time. Therefore, on the one hand, the degree of crystallinity can be increased and the heat resistance of the molded body can be improved, and on the other hand, the crystal particles are too large and their adverse effects on transparency can be avoided, so that the biodegradable molded body has both heat resistance and transparency. , suitable for food containers such as heat-resistant transparent drink cups.

Although the present invention has been disclosed as above with examples, it is not intended to limit the present invention. Those with ordinary knowledge in the technical field to which the present invention pertains can make some changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be determined by the scope of the appended patent application.

S100: mix polylactic acid, organic nucleating agent and cellulose nanofibers and prepare a composition, wherein the organic nucleating agent accounts for 0.03-9 wt % of the total weight of the composition, and the cellulose nanofibers account for 0.1% of the total weight of the composition ~15 wt % S200: Compounding the composition and forming a plurality of granules S300: Heating the particles and forming shaped bodies

FIG. 1 is a schematic flowchart of a method for manufacturing a biodegradable molded body according to an embodiment of the present invention.

Claims (12)

A composition of biodegradable shaped bodies, comprising: a polylactic acid; An organic nucleating agent, the organic nucleating agent accounts for more than 0.03 wt % of the total weight of the composition; and A cellulose nanofiber, the cellulose nanofiber accounts for more than 0.1wt% of the total weight of the composition. The composition of claim 1, wherein the organic nucleating agent accounts for 0.03-9 wt% of the total weight of the composition, and the cellulose nanofibers account for 0.1-15 wt% of the total weight of the composition. The composition of claim 2, wherein the organic nucleating agent accounts for 0.05-3 wt% of the total weight of the composition, and the cellulose nanofibers account for 0.1-5 wt% of the total weight of the composition. The composition of claim 1, wherein the cellulose nanofibers are modified cellulose nanofibers. The composition of claim 4, wherein the cellulose nanofibers comprise a plurality of glucose monomers; the modified cellulose nanofibers are cellulose monoxide nanofibers, and at least part of the glucose monomers The body has a functional group selected from the group consisting of carboxylic acids and carboxylate salts. The composition of claim 5, wherein the oxidized cellulose nanofiber is a TEMPO oxidized cellulose nanofiber, and at least part of the glucose monomers have the function of sodium carboxylate or lithium carboxylate at the C6 position base. The composition of claim 4, wherein the modified cellulose nanofibers have lactide, polylactic acid oligomer, or a graft of lactide and polylactic acid oligomer. The composition according to claim 1, wherein the organic nucleating agent is aliphatic carboxylic acid amides, aliphatic carboxylates, aliphatic alcohols, aliphatic carboxylate nucleating agents or selected from them combination. A biodegradable shaped body is made from the composition of any one of claims 1 to 6, wherein the composition is kneaded into a plurality of particles, and the particles are heated and shaped into the shaped body. The biodegradable shaped body of claim 9, wherein the particles are further heated and formed into a sheet, and the sheet is heated to form the shaped body. A method for manufacturing a biodegradable shaped body, comprising the steps of: Mixing a polylactic acid, an organic nucleating agent and a cellulose nanofiber to prepare a composition, wherein the organic nucleating agent accounts for 0.03-9 wt % of the total weight of the composition, and the cellulose nanofiber accounts for 0.03-9 wt% of the total weight of the composition. 0.1-15 wt % of the total weight of the composition; kneading the composition and forming a plurality of particles; and The particles are heated and the shaped body is formed. The manufacturing method of claim 11, wherein the step of heating the particles and forming the shaped body further comprises performing an injection molding process, a blister molding process, an injection blow molding process, a film blow molding process, a flow The formed body is formed by an extension film forming procedure.

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