Biodegradable film and biodegradable molded product having properties of flexibility and low noise

Abstract

An embodiment relates to a biodegradable film having flexibility and low noise, a method for manufacturing the same, and a biodegradable molded article, comprising a biodegradable resin composition including a first resin comprising a polylactic acid-based resin and a second resin comprising a polylactic acid-based resin comprising a polyol repeating unit.

Description

Technology Field

[0001] The present invention relates to a biodegradable film having flexibility and low noise, a biodegradable molded article, and a method for manufacturing the same. Background Technology

[0002] While non-biodegradable plastic films or molded products have been widely used as packaging materials, various biodegradable films or molded products, including polylactic acid films—aliphatic polyesters with high biodegradability of the resin itself—have recently been introduced to compensate for the disadvantages of non-biodegradable plastic films. Although polylactic acid films exhibit good mechanical and optical properties, as a semicrystalline polymer, they lack flexibility and are prone to brittleness due to their inherent crystalline structure. Furthermore, their productivity is poor because the slow crystallization rate results in long molding times, and their applications are limited due to high noise generation.

[0003] Therefore, to manufacture polylactic acid films, it is important to ensure that they possess crystallinity, crystal grain size, penetration barrier properties, mechanical properties, transparency, and heat shrinkage suitable for their intended use.

[0004] To address these issues, Japanese Patent Publication No. 2006-272712 discloses a method for manufacturing a film using a biodegradable aliphatic polyester other than polylactic acid alone; however, in this case, the glass transition temperature is too low, making it difficult to manufacture the film by the biaxial stretching method. Furthermore, the final film has low mechanical strength and a high thermal shrinkage rate, resulting in many problems during the processing stage.

[0005] In addition, Korean Patent Publication No. 2014-0120771 attempted to improve the flexibility of a polylactic acid film by introducing soft segments into a polylactic acid resin; however, the optical properties of the manufactured polylactic acid resin film, such as transparency and haze, were significantly degraded, resulting in a lack of suitability for application and usability. Prior art literature

[0006] Japanese Patent Publication No. 2006-272712, Korean Patent Publication No. 2014-0120771 The problem to be solved

[0007] In order to solve the problems of the aforementioned prior art, one embodiment aims to provide a biodegradable film having flexibility and low noise, and a method for manufacturing the same, comprising a biodegradable resin composition including a first resin comprising a polylactic acid-based resin; and a second resin comprising a polylactic acid-based resin comprising a polyol repeating unit.

[0008] Another embodiment aims to provide a biodegradable molded article comprising the above-mentioned biodegradable resin composition. means of solving the problem

[0009] To achieve the above objective, one embodiment provides a biodegradable film having a noise level of 89.5 dB or less, comprising a biodegradable resin composition including a first resin comprising a polylactic acid-based resin; and a second resin comprising a polylactic acid-based resin comprising a polyol repeating unit.

[0010] The above noise level is the average value measured by placing a biodegradable film cut to A4 size (210 mm x 297 mm) inside a 650(W) mm × 450(D) mm × 500(H) mm polycarbonate box 15 cm away from a digital noise analyzer, and repeatedly rotating the film 180 degrees and twisting it back and forth at a speed of 800 rpm with both ends held by a jig to generate noise for more than 30 seconds.

[0011] Another embodiment provides a biodegradable molded article comprising a biodegradable resin composition having an intrinsic viscosity of 1.38 dL / g to 2.04 dL / g, comprising: a first resin comprising a polylactic acid-based resin; and a second resin comprising a polylactic acid-based resin comprising a polyol repeating unit. Effects of the invention

[0012] A biodegradable film comprising a biodegradable resin composition according to an embodiment is capable of biaxial stretching and can simultaneously improve the flexibility, transparency, and noise level of the biodegradable film.

[0013] The biodegradable film according to the above embodiment can be utilized in various fields as a packaging film as well as a packaging material, thereby providing high-quality eco-friendly packaging materials.

[0014] In addition, the method for manufacturing a biodegradable film according to the embodiment is a simple, economical, and efficient method for manufacturing, and can provide a biodegradable film that is biodegradable and has excellent flexibility, transparency, and noise reduction.

[0015] Furthermore, a biodegradable molded article comprising a biodegradable resin composition according to an embodiment can improve flexibility, transparency, and noise levels, thereby diversifying the applications of the biodegradable molded article. Brief explanation of the drawing

[0017] Figure 1 is the result of differential scanning calorimetry analysis of a second resin according to one embodiment of the present invention. Figures 2 and 3 show the noise level measurement results of the biodegradable films of the embodiments and comparative examples of the present invention. Figures 4 and 5 show the noise reduction rate (%) of the biodegradable films of the embodiments and comparative examples of the present invention. Specific details for implementing the invention

[0018] The invention is described in detail below through embodiments. The embodiments are not limited to those disclosed below and may be modified in various forms as long as the essence of the invention is not altered.

[0019] In this specification, when a part is described as "comprising" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0020] In addition, all numerical ranges representing physical property values, dimensions, reaction conditions, etc. of the components described in this specification should be understood to be modified by the term "approximately" in all cases unless otherwise specified.

[0021] In this specification, terms such as first, second, third, fourth, etc. are used to describe various components, and said components are not limited by said terms. These terms are used solely for the purpose of distinguishing one component from another.

[0022] In this specification, the weight-average molecular weight of a polymer resin refers to the weight-average molecular weight (Mw) measured by gel permeation chromatography (GPC, using tetrahydrofuran as the elution solvent), and although the unit is not typically specified, it is acceptable to understand that it has units of g / mol or Da.

[0024] Biodegradable resin composition

[0025] A biodegradable resin composition according to one embodiment of the present invention comprises: a first resin comprising a polylactic acid-based resin; and a second resin comprising a polylactic acid-based resin comprising polyol repeating units.

[0026] The first resin above includes a polylactic acid-based resin.

[0027] The above polylactic acid (PLA)-based resin may have a weight-average molecular weight (Mw) of 100,000 to 1,000,000, 100,000 to 800,000, 100,000 to 500,000, or 100,000 to 300,000. The weight-average molecular weight (Mw) may be measured by gel permeation chromatography (GPC). When the weight-average molecular weight (Mw) of the above polylactic acid-based resin is within the range described above, the mechanical and optical properties of a biodegradable film or biodegradable molded article comprising the above biodegradable resin composition may be further improved.

[0028] The above polylactic acid-based resin may include L-lactic acid, D-lactic acid, D, L-lactic acid, or a combination thereof. Specifically, the above polylactic acid-based resin may be a random copolymer of L-lactic acid and D-lactic acid. Meanwhile, the polylactic acid-based resin of the first resin may not include polyol repeating units.

[0029] At this time, the content of the D-lactic acid may be, for example, 0.1% to 5% by weight based on the total weight of the polylactic acid-based resin, and specifically, 0.1% to 2% by weight, 1% to 5% by weight, 2% to 4% by weight, 1% to 2% by weight, or 2% to 3% by weight. When the content of the D-lactic acid is within the range described above, it may be advantageous in terms of improving the stretchability of the film.

[0030] The content of the L-lactic acid may be, for example, 80% to 99.9% by weight based on the total weight of the polylactic acid-based resin, and specifically, 98% to 99.9% by weight, 80% to 99% by weight, 85% to 99% by weight, 95% to 99% by weight, 96% to 98% by weight, or 96% to 97% by weight. When the content of the L-lactic acid is within the range described above, it may be advantageous in terms of improving the heat resistance properties of the film.

[0031] The above polylactic acid-based resin may have a melting temperature (Tm) of 100°C to 250°C, 110°C to 220°C, 120°C to 200°C, or 140°C to 180°C.

[0032] The above polylactic acid-based resin may have a glass transition temperature (Tg) of 30°C to 80°C, 40°C to 80°C, 40°C to 70°C, or 45°C to 65°C.

[0033] The above polylactic acid-based resin has a melt viscosity (V) at 210℃. PLA) may be 5,000 to 12,000 poise, 6,500 to 12,000 poise, 6,500 to 11,000 poise, 7,000 to 12,000 poise, 7,500 to 11,000 poise, or 8,000 to 10,000 poise.

[0034] The above polylactic acid-based resin has a melt viscosity (V) at 200℃. PLA ) may be 5,000 to 20,000 poise, 6,500 to 18,000 poise, 8,000 to 16,000 poise, 9,000 to 14,000 poise, or 10,000 to 12,000 poise. In this case, the melt viscosity can be measured using a rheometer (RDS) under conditions of 1 to 400 rad / s, for example, under conditions of about 100 rad / s.

[0035] According to an embodiment of the present invention, the content of the first resin may be 35% to 97% by weight, 35% to 95% by weight, 37% to 95% by weight, or 40% to 90% by weight, based on the total weight of the biodegradable resin composition.

[0036] When the content of the first resin is within the range described above, the mechanical properties and optical properties such as haze of the biodegradable resin composition and the biodegradable film or molded article containing it can be improved, brittleness can be reduced and flexibility can be increased to prevent breakage or cracking, and noise levels can be reduced.

[0037] The second resin above includes a polylactic acid-based resin containing polyol repeating units. When such a flexible polylactic acid-based resin is used, the bubble stability, durability, flexibility, and tensile strength can be further improved.

[0038] The polylactic acid-based resin containing the above-mentioned polyol repeating unit comprises a hard segment containing the polylactic acid repeating unit and a soft segment containing the above-mentioned polyol repeating unit.

[0039] The polylactic acid-based resin containing the above-mentioned polyol repeating unit can exhibit biodegradability and eco-friendly characteristics unique to biomass-based resins by including the polylactic acid repeating unit as a hard segment. Furthermore, flexibility is significantly improved by including the above-mentioned polyolefin-based polyol repeating unit as a soft segment, and the possibility of the soft segment leaching is reduced as the soft segment is introduced into the polylactic acid resin itself in a combined form with the hard segment.

[0040] The above soft segment may include one or more repeating units selected from the group consisting of polyurethane-based polyol repeating units, polyolefin-based polyol repeating units, aliphatic polyether-based repeating units, and aliphatic polyester-based repeating units.

[0041] The above polyolefin-based polyol repeating unit may have a structure in which polyolefin-based polyol constituent units are connected linearly or in a branched manner via urethane bonds (-C(=O)-NH-) or ester bonds (-C(=O)-O-), and the polyolefin-based polyol constituent units may be connected linearly or in a branched manner via urethane bonds or ester bonds to form the polyolefin-based polyol repeating unit.

[0042] The polylactic acid-based resin containing the above polyol repeating unit may include a block copolymer in which the terminal carboxyl group of the polylactic acid repeating unit included in the hard segment is connected to the terminal hydroxyl group of the polyolefin-based polyol constituent unit included in the soft segment by an ester bond, or a block copolymer in which the block copolymer is connected in a linear or branched manner via a urethane bond.

[0043] The polylactic acid-based resin containing the above-mentioned polyol repeating unit includes a block copolymer in which the polylactic acid repeating unit and the polyolefin-based polyol repeating unit are combined, thereby suppressing the leaching of soft segments, etc., while imparting excellent properties such as moisture resistance, transparency, mechanical properties, heat resistance, or anti-blocking properties to the biodegradable film. Furthermore, when at least a portion of the polylactic acid constituent unit or repeating unit and the polyolefin-based polyol repeating unit are in the form of a block copolymer, the molecular weight distribution, glass transition temperature (Tg), and melting temperature (Tm) of the polylactic acid resin are optimized, thereby further improving the mechanical properties, flexibility, and heat resistance of the film.

[0044] However, not all of the polylactic acid repeating units included in the polylactic acid-based resin containing the polyol repeating unit are in the form of a block copolymer bonded to the polyolefin-based polyol constituent unit or repeating unit, and at least some of the polylactic acid repeating units may be in the form of a polylactic acid homopolymer not bonded to the polyolefin-based polyol constituent unit or repeating unit. For example, it may be in the form of a mixture further comprising a polylactic acid homopolymer in the block copolymer.

[0045] The above polyolefin-based polyol repeating unit may be polypropylene glycol (PPG), polyethylene glycol (PEG), or polybutadiene (poly(1,2-butadiene) or poly(1,3-butadiene)).

[0046] The polylactic acid-based resin containing the above polyol repeating unit has a melt viscosity (V) at 160°C. PLA ) may be 10,000 to 50,000 poise, 15,000 to 40,000 poise, 20,000 to 35,000 poise, 23,000 to 30,000 poise, 25,000 to 28,000 poise, or 26,000 to 27,000 poise.

[0047] The polylactic acid-based resin containing the above polyol repeating unit has a melt viscosity (V) at 170°C. PLA ) may be 1,500 poise to 10,000 poise, 2,000 poise to 8,000 poise, 2,500 poise to 6,000 poise, 2,800 poise to 5,000 poise, or 3,000 poise to 4,000 poise. In this case, the melt viscosity can be measured using a rheometer (RDS).

[0048] The melt index of the polylactic acid-based resin containing the above polyol repeating unit may be 1 g / 10 min to 50 g / 10 min, 5 g / 10 min to 45 g / 10 min, 10 g / 10 min to 40 g / 10 min, 15 g / 10 min to 37 g / 10 min, and 20 g / 10 min to 35 g / 10 min. Within the above preferred melt index range, the processability of pyrolysis or sheet forming can be further improved while reducing the extrusion process load.

[0049] In addition, the polylactic acid-based resin containing the polyol repeating unit may have a melting temperature (Tm) of 145°C to 195°C, 150°C to 190°C, 155°C to 180°C, 160°C to 178°C, or 160°C to 165°C. When the melting temperature is within the ranges described above, the heat resistance of the biodegradable film can be improved, and excessive viscosity increase can be prevented during melt processing by methods such as extrusion.

[0050] The glass transition temperature (Tg) of the polylactic acid-based resin containing the above-mentioned polyol repeating unit may be 20°C to 55°C, 25°C to 50°C, 30°C to 50°C, 35°C to 50°C, or 40°C to 50°C. When the glass transition temperature is within the ranges described above, the flexibility or stiffness of the biodegradable film is appropriately maintained, so it can be preferably used as a packaging film.

[0051] The cold crystallization temperature (Tcc) of the polylactic acid-based resin containing the above polyol repeating unit may be 55°C to 100°C, 60°C to 90°C, 63°C to 87°C, 65°C to 85°C, 70°C to 85°C, or 75°C to 85°C. Within the above preferred cold crystallization temperature range, the process range of stretching may be further extended.

[0052] According to an embodiment of the present invention, the content of the second resin may be 3% to 65% by weight, 5% to 65% by weight, 8% to 63% by weight, or 10% to 60% by weight, based on the total weight of the biodegradable resin composition.

[0053] When the content of the second resin is within the range described above, the optical properties of transparency and haze of the biodegradable resin composition and the biodegradable film or molded article containing it can be maintained, and the flexibility can be increased to reduce noise.

[0054] According to a specific example, the biodegradable film may comprise 35% to 97% by weight of the first resin and 3% to 65% by weight of the second resin, based on the total weight of the biodegradable resin composition.

[0055] Additionally, the biodegradable film may contain the first resin and the second resin in a weight ratio of 1:0.1 to 1:1.7, or in a weight ratio of 1:0.5 to 1:1.7. As an example, the biodegradable film may contain the first resin and the second resin in a weight ratio of 1:0.67 to 1:1.5. As a specific example, the biodegradable film may contain the first resin and the second resin in a weight ratio of 1:0.67 to 1:1.3, 1:0.67 to 1:1.1, 1:0.67 to 1:0.9, 1:0.9 to 1:1.5, 1:0.9 to 1:1.5, 1:1.1 to 1:1.5, or 1:0.8 to 1:1.3.

[0056] Meanwhile, the biodegradable resin composition may further include, in addition to the first resin and the second resin, a third resin comprising a polyhydroxyalkanoate-based resin, and / or a fourth resin comprising an aliphatic polyester-based resin or an aliphatic-aromatic copolymer polyester-based resin different from that used in the first resin.

[0057] According to one embodiment, the biodegradable resin composition further comprises a third resin comprising a polyhydroxyalkanoate-based resin.

[0058] The above polyhydroxyalkanoate (PHA)-based resin may be a homopolymer or a copolymer. According to one embodiment, the polyhydroxyalkanoate-based resin may be a homopolymer or a copolymer containing 4-hydroxybutyrate (4-HB) repeating units, and if the polyhydroxyalkanoate-based resin is a copolymer, specifically, it may be a copolymer containing two or more different repeating units in which different repeating units are randomly distributed in the polymer chain.

[0059] The above polyhydroxyalkanoate-based resin comprises one or more selected from the group consisting of lactic acid, glycolic acid, 2-hydroxybutyrate (2-HB), 3-hydroxybutyrate (3-HB), 3-hydroxyhexanoate (3-HH), 3-hydroxypropionate (3-HP), 3-hydroxyvalerate (3-HV), 3-hydroxyheptanoate (3-HHep), 3-hydroxyoctanoate (3-HO), 3-hydroxynonanoate (3-HN), 3-hydroxydecanoate (3-HD), 3-hydroxydodecanoate (3-HDd), 4-hydroxyvalerate (4-HV), 5-hydroxyvalerate (5-HV), and 6-hydroxyhexanoate (6-HH). Includes a repeating unit.

[0060] For example, the polyhydroxyalkanoate resin may be one or more selected from poly(4-hydroxybutyrate) (P4HB) and poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P(3HB4HB)).

[0061] As an example, the above polyhydroxyalkanoate-based resin may include 4-HB repeating units, and accordingly, biodegradability is improved and additional noise reduction is possible.

[0062] As a specific example, the polyhydroxyalkanoate-based resin may contain 4-hydroxybutyrate (4-HB) repeating units in an amount of 10 mol% to 65 mol%. More specifically, the content of 4-HB repeating units in the polyhydroxyalkanoate-based resin may be 20 mol% to 65 mol%, 25 mol% to 65 mol%, 30 mol% to 60 mol%, 35 mol% to 55 mol%, or 40 mol% to 50 mol%. When the content of 4-HB repeating units is within the ranges described above, the crystallinity of the polyhydroxyalkanoate-based resin can be appropriately controlled.

[0063] The above-mentioned polyhydroxyalkanoate-based resin is formed by chemical synthesis or by polymerizing one or more monomer repeating units present in microorganisms using an enzyme catalyst, and may be crystalline, semicrystalline, or amorphous depending on the molecular structure, and preferably amorphous. When such an amorphous polyhydroxyalkanoate-based resin is used, film-forming processability and biodegradability can be further enhanced.

[0064] In addition, the polyhydroxyalkanoate-based resin may include structural isomers, enantiomers, or geometric isomers.

[0065] In addition, the weight-average molecular weight (Mw) of the polyhydroxyalkanoate-based resin may be 50,000 to 1,000,000, 100,000 to 800,000, 100,000 to 500,000, or 100,000 to 300,000.

[0066] The above polyhydroxyalkanoate-based resin may not have a melting temperature (Tm).

[0067] The above polyhydroxyalkanoate-based resin may have a glass transition temperature (Tg) of -70°C to 30°C, -50°C to 10°C, or -30°C to -10°C.

[0068] The above polyhydroxyalkanoate-based resin may have a melt index of 0.1 g / 10 min to 5 g / 10 min, 0.3 g / 10 min to 3 g / 10 min, 0.5 g / 10 min to 5 g / 10 min, or 0.7 g / 10 min to 2 g / 10 min. In this specification, the melt index may be measured, for example, under conditions of 190°C and 2.16 kg.

[0069] According to one embodiment, the content of the third resin may be 1% to 25% by weight based on the total weight of the biodegradable resin composition. Specifically, the content of the third resin may be 1% to 18% by weight, 1% to 15% by weight, 5% to 15% by weight, or 8% to 13% by weight based on the total weight of the biodegradable resin composition.

[0070] When the content of the third resin is within the range described above, the flexibility of the biodegradable resin composition and the biodegradable film or molded article containing it is increased, which can further reduce the noise level.

[0071] The fourth resin may include an aliphatic polyester resin or an aliphatic-aromatic copolymer polyester resin different from that used in the first resin.

[0072] According to one embodiment, the aliphatic polyester resin or the aliphatic-aromatic copolymer polyester resin may comprise, for example, one or more selected from the group consisting of polybutylene adipate terephthalate (PBAT) resin, polybutylene succinate (PBS) resin, polybutylene adipate (PBA) resin, polybutylene succinate-adipate (PBSA) resin, polybutylene succinate-terephthalate (PBST) resin, polyhydroxybutylate-valerate (PHBV) resin, polycaprolactone (PCL) resin, and polybutylene succinate adipate terephthalate (PBSAT) resin.

[0073] The above-mentioned fourth resin may be included in an amount of, for example, greater than 0 weight% to 20 weight% or less, for example, 1 weight% or more to 15 weight% or less, or for example, 1 weight% or more to 10 weight% or less, based on the total weight of the above-mentioned biodegradable resin composition.

[0074] In addition, according to one embodiment, the biodegradable resin composition may further include one or more additives selected from the group consisting of conventional thickeners, electrostatic agents, antistatic agents, antioxidants, heat stabilizers, UV blockers, anti-blocking agents, impact-resistant reinforcing agents, and other inorganic lubricants. The additives may be added within a range that does not impair the effects of the invention.

[0075] The above-mentioned thickener may be an aromatic diisocyanate, an aliphatic diisocyanate, an isocyanurate, bisoxazolin, a carboxylic acid anhydride, or an epoxide, and for example, ADR-4468 may be used, but is not limited thereto.

[0076] The content of the above-mentioned thickener may be 0.01% to 5% by weight, 0.1% to 3% by weight, 0.1% to 1% by weight, 0.2% to 0.7% by weight, or 0.3% to 0.5% by weight based on the total weight of the biodegradable resin composition. When the content of the above-mentioned thickener is within the range described above, the intrinsic viscosity of the biodegradable resin can be increased to improve processability, and at the same time, the tensile strength of the biodegradable film containing it can be increased to improve mechanical strength.

[0077] The above antioxidant may be selected from the group consisting of phosphorus-based antioxidants, phenolic-based antioxidants, or pentaerythritol-based antioxidants, and for example, Irganox 1010 or Irgafos 168 may be used, but are not limited thereto.

[0078] The content of the above antioxidant may be 0 to 5 weight%, 0.01 to 4 weight%, 0.1 to 3 weight%, 1 to 3 weight%, 1 to 2 weight%, 0.01 to 0.3 weight%, or 0.05 to 0.3 weight% based on the total weight of the biodegradable resin composition.

[0079] According to one embodiment, the intrinsic viscosity (IV) of the biodegradable resin composition is 1.38 dL / g to 2.04 dL / g. Specifically, the intrinsic viscosity of the biodegradable resin composition may be 1.39 to 1.99 dL / g, 1.4 to 1.97 dL / g, 1.5 to 1.968 dL / g, or 1.56 to 1.968 dL / g. When the intrinsic viscosity is within the range described above, processability can be improved when manufacturing biodegradable films and biodegradable molded articles.

[0081] biodegradable film

[0082] A biodegradable film according to one embodiment comprises a biodegradable resin composition comprising: a first resin comprising a polylactic acid-based resin; and a second resin comprising a polylactic acid-based resin comprising a polyol repeating unit.

[0083] The thickness of the above biodegradable film may be 5 μm to 100 μm, 10 μm to 80 μm, 15 μm to 70 μm, 20 μm to 60 μm, 25 μm to 55 μm, or 30 μm to 50 μm.

[0084] The thickness variation in the transverse direction (TD) or longitudinal direction (MD) of the above biodegradable film may have a lower limit value of 0 μm or more or 0.1 μm or more, and an upper limit value of 15 μm or less, 12 μm or less, 10 μm or less, 9 μm or less, 8 μm or less, 6 μm or less, 4 μm or less, or 2 μm or less. As one embodiment, the thickness variation in the transverse direction (TD) or longitudinal direction (MD) of the above biodegradable film may be 9 μm or less. When the thickness variation in the transverse direction (TD) or longitudinal direction (MD) is within the range described above, it is possible to produce a film of uniform thickness, thereby improving the quality of the manufactured film.

[0085] According to one embodiment, the biodegradable film has a transmittance of 90% or more. Specifically, the biodegradable film may have a transmittance of 92% or more, 93% or more, 94% or more, or 94.3% or more. The transmittance may be a value measured according to ASTM D1003.

[0086] In addition, the biodegradable film may have a haze of 10% or less, 7% or less, 4% or less, 2% or less, or 1.3% or less. The haze can be measured using NIPPON DENSHOKU's Hazemeter (model name: NDH 8000).

[0087] When the transmittance or haze is within the aforementioned range, excellent transparency and visual uniformity can be achieved, and due to the excellent optical characteristics, it can be utilized in products for various applications, and is particularly advantageous for application as a packaging material.

[0088] According to one embodiment, the biodegradable film has a noise level of 89.5 dB or less. Specifically, the biodegradable film may have a noise level of 89 dB or less, 86 dB or less, 85 dB or less, 83 dB or less, or 79.5 dB or less.

[0089] The above noise level is the average value measured by placing a biodegradable film cut to A4 size (210 mm x 297 mm) inside a 650(W) mm × 450(D) mm × 500(H) mm polycarbonate box 15 cm away from a digital noise analyzer, and repeatedly rotating the film 180 degrees and twisting it back and forth at a speed of 800 rpm with both ends held by a jig to generate noise for more than 30 seconds.

[0090] In particular, when the noise level of the above-mentioned biodegradable film is within the aforementioned range, there is an advantage in being able to provide high-quality packaging materials due to the low noise level.

[0091] According to one embodiment, the biodegradable film may have a longitudinal (MD) Young's modulus of 350 kgf / mm² or less, 330 kgf / mm² or less, 325 kgf / mm² or less, or 200 kgf / mm² or less. The biodegradable film may have a transverse (TD) Young's modulus of 470 kgf / mm² or less, 460 kgf / mm² or less, 445 kgf / mm² or less, or 220 kgf / mm² or less.

[0092] The above Young's modulus was determined by cutting a biodegradable film specimen to a width of 15 mm in accordance with ASTM D882, mounting it with a chuck spacing of 50 mm, and then testing the specimen using a tensile testing machine (Instron, 5566A) at a tensile speed of 200 mm / min, and measuring the slope of the straight line from the starting point of measurement to the point where the elongation reached 3% as Young's modulus (kgf / mm²).

[0093] The above biodegradable film may have an average Young's modulus of 395 kgf / mm² or less. For example, the above biodegradable film may have an average Young's modulus of 390 kgf / mm² or less, 380 kgf / mm² or less, 300 kgf / mm² or less, or 210 kgf / mm² or less. Specifically, the average Young's modulus of the above biodegradable film may be 150 kgf / mm² to 395 kgf / mm², 180 kgf / mm² to 380 kgf / mm², 210 kgf / mm² to 380 kgf / mm², 170 kgf / mm² to 230 kgf / mm², or 180 kgf / mm² to 210 kgf / mm².

[0094] The above average Young's modulus is the average value of the longitudinal (MD) Young's modulus and the transverse (TD) Young's modulus.

[0095] Generally, in the case of a biodegradable film containing only the first resin and not the second resin, the average Young's modulus exceeds 395 kgf / mm², which significantly reduces flexibility and may limit the application of the film. When the average Young's modulus of the biodegradable film satisfies the aforementioned range, it has excellent flexibility, allowing for the expansion of various applications, and furthermore, processability, moldability, and productivity can be further improved.

[0096] The above biodegradable film may have a longitudinal tensile strength of 8 to 12.3 kgf / mm², 8.5 to 12 kgf / mm², 8.6 to 11.9 kgf / mm², or 8.8 to 11.7 kgf / mm², and a transverse tensile strength of 8 to 18.8 kgf / mm², 8.5 to 18.5 kgf / mm², 9 to 18 kgf / mm², or 10.1 to 15 kgf / mm².

[0097] The above biodegradable film may have a longitudinal elongation of 50 to 200%, 60 to 180%, or 70 to 175%, and a transverse elongation of 35 to 150%, 40 to 140%, 45 to 120%, or 50 to 110%.

[0098] The above tensile strength and elongation are measured by cutting a biodegradable film specimen to a width of 15 mm in accordance with ASTM D882, and then measuring the specimen using a tensile testing machine (Instron, 5566A) at a tensile speed of 200 mm / min.

[0100] Method for manufacturing biodegradable film

[0101] The method for manufacturing a biodegradable film according to an embodiment of the present invention involves melt-extruding the biodegradable resin composition to produce a sheet, and then stretching and heat-setting it, thereby further improving moldability, processability, and productivity, and enabling the production of a biodegradable film that meets the purpose of the present invention in an economical and efficient manner.

[0102] In particular, the method for manufacturing the biodegradable film can simultaneously improve the flexibility and noise level of the biodegradable film while maintaining excellent mechanical and optical properties by controlling the content of the first resin, the second resin, and / or the third resin to a specific range.

[0103] The description regarding the polylactic acid-based resin, the polylactic acid-based resin containing polyol repeating units, and the polyhydroxyalkanoate-based resin included in the first to third resins above is as described above.

[0104] In addition, depending on the intended use and physical property design, a fourth resin and additives may be added in addition to the first resin, the second resin, and the third resin, and the fourth resin and additives are as described above.

[0105] According to one embodiment, a sheet can be formed by mixing a first resin and a second resin, or a first to third resin, and melt-extruding. Additionally, a biodegradable pellet (blended chip) can be obtained by mixing and extruding a first resin and a second resin, or a first to third resin, and a biodegradable sheet and film can be obtained using the same.

[0106] In addition, the melt extrusion temperature may be, for example, 170°C to 230°C, 170°C to 210°C, 180°C to 210°C, or 190°C to 210°C. The extrusion may utilize a single-screw extruder, a twin-screw extruder, or a T-die.

[0107] Additionally, according to an embodiment, the method may further include a step of drying the first resin, the second resin, or the third resin before the melt extrusion. The drying step may be performed, for example, at 40°C to 130°C or at 80°C to 90°C for 4 to 24 hours.

[0108] Meanwhile, the melt-extruded sheet can be formed through casting such as electrostatic casting using a casting roll, band casting, or drum casting. The casting temperature may be, for example, 5°C to 35°C, 10°C to 30°C, or 15°C to 25°C.

[0109] The method for manufacturing the above biodegradable film may include a step of manufacturing a film by stretching the melt-extruded sheet. Specifically, the melt-extruded sheet may be cut and then biaxially stretched, and the biaxial stretching step may include a step of stretching the longitudinal direction (MD) by 2 to 4 times, 2.5 to 3.5 times, or 2.7 to 3.3 times after preheating, and a step of stretching the transverse direction (TD) by 3 to 6 times, 3.2 to 5.5 times, or 3.5 to 5 times.

[0110] By performing biaxial stretching in both directions on the above-mentioned melt-extruded sheet, the physical properties and moldability of the biodegradable film can be further improved, thereby enabling the realization of high-quality packaging materials.

[0111] If uniaxial stretching is performed in only one direction, either the longitudinal or transverse direction, the thickness variation of the biodegradable film may be severe, the strength of the side that was not stretched may decrease, and thermal properties may also deteriorate.

[0112] The method for manufacturing the above biodegradable film may include a step of heat-setting the stretched film (heat-setting step), a step of cooling (cooling step), and / or a step of winding (winding step), etc.

[0113] In addition, the heat setting step may be performed at 90°C to 180°C, 110°C to 170°C, 130°C to 160°C, or 140°C to 150°C, and may be performed for 5 to 30 seconds or 5 to 15 seconds.

[0114] The above cooling step may be performed at 50°C or lower, 40°C or lower, 30°C or lower, 25°C or lower, 5 to 50°C, 10 to 30°C, 15 to 25°C, or 20 to 25°C.

[0115] When the biodegradable film is manufactured according to the manufacturing method of the embodiment, it is economical and efficient, and may be more effective in manufacturing a biodegradable film having the desired composition and physical properties.

[0117] Biodegradable molded products

[0118] Another embodiment may provide a biodegradable molded article manufactured from the above biodegradable resin composition. Specifically, the biodegradable molded article comprises a first resin comprising a polylactic acid-based resin; and a second resin comprising a polylactic acid-based resin comprising a polyol repeating unit; and comprises a biodegradable resin composition having an intrinsic viscosity of 1.38 dL / g to 2.04 dL / g.

[0119] Specifically, the biodegradable molded article may be manufactured by molding the biodegradable resin composition by methods known in the art, such as extrusion or injection molding, and the biodegradable molded article may be an injection molded article, an extrusion molded article, a thin film molded article, or a blown molded article, but is not limited thereto.

[0120] Specifically, when manufacturing a biodegradable molded article by injection molding, the mold temperature may be set to approximately 130°C or higher. If the biodegradable molded article is in the form of a film or sheet, it may be manufactured into various films or sheets by methods such as unoriented, uniaxial stretching, or biaxial stretching. If the biodegradable molded article is a fiber, it may be various fibers such as unoriented yarn, oriented yarn, or super-oriented yarn, and may be used as a woven fabric, knitted fabric, nonwoven fabric (spunbond, meltblown, staple), rope, or net. Such biodegradable molded articles may be used as electrical components such as computer accessories, electronic components, building materials, automotive parts, machine parts, daily necessities, coatings for parts in contact with chemicals, industrial chemical-resistant fibers, etc.

[0121] In addition, the above-mentioned biodegradable molded product may be in the form of a film or sheet that can be used as an agricultural mulching film, disposable gloves, food packaging material, etc., may be in the form of a fiber that can be used as a fabric, knitted fabric, non-woven fabric, rope, etc., or may be in the form of a container that can be used as a food packaging container such as a lunch box.

[0122] The above biodegradable molded article may be an automotive and industrial headlamp bezel. Additionally, the above biodegradable molded article may be an electrical component or an electronic component.

[0123] In particular, the above-mentioned biodegradable molded article has excellent barrier properties and low noise levels, and can provide excellent physical properties and quality that satisfy the mechanical or thermal properties required depending on the application. In addition, the above-mentioned biodegradable molded article can be 60% to 100% biodegraded within 45 to 180 days in natural conditions and can be composted under conditions of a constant temperature of 20 to 60°C and a constant humidity of 30 to 90%.

[0124]

[0125] [Example]

[0126] The above contents are explained in more detail by the following examples, but are not limited thereto.

[0128] Example 1: Preparation of biodegradable film

[0129] As the first resin, a polylactic acid resin (Nature Works LLC, 4032D) with a D-lactide content of about 1.4% and a melt viscosity of about 8,770 poise under conditions of about 210°C and 100 rad / s was prepared. As the second resin, a polylactic acid resin (SK Chemical, ECOPLAN FLEX 820) containing polyol repeating units having the properties shown in Table 1 was mixed according to Table 2 to prepare a biodegradable resin composition.

[0130] Physical properties (units) Measurement method (condition) value Melt index (g / 10 min) ASTM D1238 (2160 g, 180℃) 20 ~ 35 Melting temperature (°C) ASTM D3418 (10℃ / min) 160 ~ 165 Glass transition temperature (°C) ASTM D3418 (10℃ / min) 33~50 Cold crystallization temperature (°C) ASTM D3418 (10℃ / min) 70~85

[0132] The above biodegradable resin composition was melt-extruded through a single-screw extruder and a T-die extruder at a temperature of 190 to 200°C, and then electrostatically cast onto a casting roll cooled to 15 to 25°C to obtain a biodegradable sheet according to Table 3.

[0133] The manufactured biodegradable sheet was cut into 90 mm x 90 mm pieces and stretched 3.0 times in the longitudinal direction (MD) and 4.0 times in the transverse direction (TD). The stretched sheet was then heat-set at 150°C for 10 seconds in the heat treatment section of a tenter and cooled to produce a biodegradable film with the thickness according to Table 4.

[0135] Examples 2 to 6

[0136] As shown in Table 2 below, a biodegradable film was prepared by performing the same procedure as in Example 1, except that the manufacturing conditions, such as the weight ratio of the first resin and the second resin contained in the final biodegradable film, were changed. In Example 5, ADR-4468 (BASF, Joncryl) was further added as a thickener.

[0138] Examples 7 and 8

[0139] As shown in Table 2 below, a biodegradable film was prepared in the same manner as in Example 1, except that the third resin included an amorphous polyhydroxyalkanoate (a-PHA) resin (CJ CheilJedang, PHACT) in which 3-hydroxybutyrate (3-HB) and 4-hydroxybutyrate (4-HB) were copolymerized, and the copolymerization ratio of 4-hydroxybutyrate (4-HB) was 30 to 60 mol%.

[0141] Comparative Examples 1 to 3

[0142] As shown in Table 2 below, a biodegradable film was prepared by performing the same procedure as Example 1 above, except that the manufacturing conditions were different, such as using only the first resin or the second resin, which is a polylactic acid-based resin.

[0144] The compositions of the biodegradable films prepared according to Examples 1 to 8 and Comparative Examples 1 to 3 are summarized in Table 2 below.

[0145] (Unit: weight%) 1st resin 2nd Suji Third Suji Thickener Example 1 90 10 - - Example 2 80 20 - - Example 3 60 40 - - Example 4 50 50 - - Example 5 49.7 50 - 0.3 Example 6 40 60 - - Example 7 40 50 10 - Example 8 50 40 10 - Comparative Example 1 100 - - - Comparative Example 2 100 - - - Comparative Example 3 - 100 - -

[0147] Test example

[0148] Physical property measurements and performance evaluations of the biodegradable sheets or biodegradable films prepared according to the above examples and comparative examples were carried out in the following manner.

[0150] Test Example 1: Intrinsic Viscosity (IV)

[0151] The viscosity of the sample was measured by dissolving the sample in orthochlorophenol (O-Chlorophenol) and determining the drop time of the sample using a BS-type NO2 Ostwald viscometer.

[0153] Test Example 2: Thickness and Variation

[0154] The thickness of a biodegradable film sample was measured in the longitudinal (MD) or transverse (TD) direction using a thickness gauge from TOYOSEKI. Specifically, the thickness was measured at multiple points along each direction (MD, TD) of the film sample, and the average thickness for each direction was calculated. In addition, the difference values ​​at the measurement points for the average thickness for each direction (MD, TD) were calculated, and the largest difference value among them was taken as the thickness deviation (R-difference).

[0156] Test Example 3: Haze and Transmittance

[0157] The transmittance (%) and haze (%) of the biodegradable films prepared in the examples and comparative examples were measured according to ASTM D1003 using a NIPPON DENSHOKU Hazemeter (model name: NDH 8000).

[0159] Test Example 4: Noise level

[0160] The biodegradable film prepared in the examples and comparative examples was cut to an A4 size of 210 mm x 297 mm inside a 650 (W) mm × 450 (D) mm × 500 (H) mm box made of polycarbonate, the biodegradable film was placed 15 cm away from a digital noise analyzer (Cirrus Research PlC, model name: CR-162C), and the ends of the film were held with a jig and rotated 180 degrees and twisted back and forth at a speed of 800 rpm repeatedly to produce noise for more than 30 seconds, and the average value of the measured value (dB) was calculated.

[0162] Test Example 5: Young's Modulus

[0163] In accordance with ASTM D882, a biodegradable film specimen was cut to a width of 15 mm and mounted with a chuck spacing of 50 mm. The specimen was then tested using a tensile testing machine (Instron, 5566A) at a tensile speed of 200 mm / min, and the slope of the line from the starting point to the point where the elongation reached 3% was measured as Young's modulus (kgf / mm²). The average Young's modulus is the average value of the longitudinal (MD) Young's modulus and the transverse (TD) Young's modulus.

[0165] Test Example 6: Tensile Strength and Elongation

[0166] According to ASTM D882, a biodegradable film specimen was cut to a width of 15 mm and mounted with a clamping distance of 50 mm. The specimen was then tested using a tensile testing machine (Instron, 5566A) at a tensile speed of 200 mm / min to measure the tensile strength (kgf / mm²) and elongation (%).

[0168] The physical properties measured for the biodegradable sheets prepared according to Examples 1 to 8 and Comparative Examples 1 to 3 are summarized in Table 3 below.

[0169] division Intrinsic viscosity (dL / g) Tensile strength (MD, kgf / mm²) Young's modulus (MD, kgf / mm²) New Rate (MD, %) Example 1 1.967 6.7 250 7 Example 2 1.895 6.38 238 8 Example 3 1.755 5.76 212 13 Example 4 1.697 4.29 171 69 Example 5 1.782 4.48 174 52 Example 6 1.639 3.48 152 175 Example 7 1.562 3.03 141 398 Example 8 1.629 3.71 163 310 Comparative Example 1 1.969 6.94 270 6 Comparative Example 2 2.047 7.15 247 5 Comparative Example 3 1.373 2.3 59 413

[0171] When comparing Comparative Examples 1 and 2, which contain only the first resin, with Examples 1 to 8, the biodegradable sheet containing the biodegradable resin composition according to the embodiment can maintain the mechanical properties of a conventional polylactic acid resin sheet at the same level or higher than the level required by the product. Examples 7 and 8, which contain the third resin, have a higher elongation compared to Comparative Examples 1 and 2, but a lower elongation compared to Comparative Example 3, which contains only the second resin, and an increase in tensile strength and Young's modulus.

[0173] The physical properties measured for the biodegradable films prepared according to Examples 1 to 8 and Comparative Examples 1 to 3 are summarized in Table 4 below. In addition, Figures 2 and 3 show the noise level measurement results of the biodegradable films of the Examples and Comparative Examples, and Figures 4 and 5 show the noise reduction rate (%) of the biodegradable films of the Examples and Comparative Examples.

[0174] division Thickness (㎛) Transmittance (%) Haze (%) Noise level (dB) Tensile strength (kgf / mm²) Young's modulus (kgf / mm²) Growth Rate (%) MD (R car) TD(R-cha) MD TD MD TD MD TD Example 1 33.5(4.5) 40.7(1.2) 94.3 0.49 88.8 9.31 18.03 325 441 93 80 Example 2 32.0(4.0) 34.5(4.0) 94.3 0.6 89.2 9.6 11.58 303 408 74 52 Example 3 33.7(2.1) 33.7(2.1) 94.3 1.22 85.6 9.93 11.55 267 353 113 65 Example 4 45.5(4.7) 47.8(4.6) 94.4 0.5 86.0 8.85 13.27 247 314 121 95 Example 5 41.8(5.7) 42.0(0.8) 94.4 0.69 82.4 10.61 14.76 240 305 142 99 Example 6 41.0(3.7) 45.0(0) 94.3 0.64 81.9 11.7 15.3 285 174 174 110 Example 7 44.7(0.6) 45.3(1.3) 93.8 7.46 77.9 9.19 10.16 174 186 150 109 Example 8 40.3(1.0) 40.0(1.8) 93.8 9.2 78.4 9.48 12.08 196 217 137 108 Comparative Example 1 34.0(9.2) 34.5(1.3) 94.4 0.5 89.8 12.39 18.89 322 473 114 78 Comparative Example 2 43.3(12.1) 44.3(4.0) 94.3 0.7 91.8 8.43 17.03 328 490 107 68 Comparative Example 3 Unstretchable (high contraction)

[0176] As a result of the test, Comparative Example 3, which contains only the second resin, could not be manufactured into a film due to high shrinkage. When comparing Comparative Examples 1 and 2, which contain only the first resin, with Examples 1 to 8, the biodegradable film containing the biodegradable resin composition according to the embodiment exhibits optical properties (transmittance and haze) that are the same as or at the same level as conventional polylactic acid resin films, and can maintain the mechanical properties (tensile strength and elongation) of the film at the same level as or higher than that required by the product as conventional polylactic acid resin films.

[0177] Examples 1 to 8 exhibit excellent flexibility with an average Young's modulus, which is the average value of the longitudinal and transverse Young's modulus, of 383 kgf / mm² or less.

[0178] When Examples 1 to 6 are compared with Comparative Example 1 or 2, the noise level was reduced by up to 10.8%, and it can be seen that the noise reduction rate increases with increasing content of the second resin (Fig. 4). Examples 7 and 8 containing the third resin showed a noise level reduction of 15.1% and 14.6%, respectively, compared with Comparative Example 2, and when comparing Examples 3 and 8 with the same content of the second resin, the noise level of Example 8 was further reduced by 9.9%, and when comparing Examples 4 and 7, the noise level of Example 7 was further reduced by 8.8% (Fig. 5).

Claims

Claim 1 A first resin comprising a polylactic acid-based resin; A biodegradable resin composition comprising a second resin comprising a polylactic acid-based resin containing polyol repeating units and a polyol repeating unit in a weight ratio of 1:0.1 to 1:1.7, wherein the biodegradable resin composition has an intrinsic viscosity (IV) of 1.38 dL / g to 2.04 dL / g, and the polylactic acid-based resin containing polyol repeating units has a melt index of 20 g / 10 min to 35 g / 10 min, a melting temperature (Tm) of 160 ℃ to 165 ℃, a glass transition temperature (Tg) of 33 ℃ to 50 ℃, a cold crystallization temperature (Tcc) of 70 ℃ to 85 ℃, and a noise level of 89.5 dB or less; wherein the noise level is 650(W) mm × 450(D) mm × 500(H) made of polycarbonate This is the average value of the measured values ​​obtained by placing a biodegradable film cut to A4 size (210 mm x 297 mm) inside a box of mm at a distance of 15 cm from a digital noise analyzer, and holding both ends of the film with a jig, rotating it 180 degrees, and twisting it back and forth at a speed of 800 rpm for more than 30 seconds to generate noise. Claim 2 A biodegradable film according to claim 1, wherein the biodegradable resin composition further comprises a third resin comprising a polyhydroxyalkanoate-based resin, and the content of the third resin is 1% to 25% by weight based on the total weight of the biodegradable resin composition. Claim 3 In claim 2, the polyhydroxyalkanoate-based resin comprises a 4-hydroxybutyrate (4-HB) repeating unit in an amount of 10 mol% to 65 mol%, forming a biodegradable film. Claim 4 A biodegradable film according to claim 1, comprising 35% to 97% by weight of the first resin and 3% to 65% by weight of the second resin, based on the total weight of the biodegradable resin composition. Claim 5 A biodegradable film according to claim 1, comprising the first resin and the second resin in a weight ratio of 1:0.67 to 1:1.

5. Claim 6 delete Claim 7 A biodegradable film according to claim 1, having a transmittance of 90% or more as measured according to ASTM D1003. Claim 8 A biodegradable film according to claim 1, having an average Young's modulus of 395 kgf / mm² or less. Claim 9 A biodegradable film according to claim 1, wherein the thickness variation in the longitudinal direction (MD) of the biodegradable film is 9 μm or less. Claim 10 delete

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