Biodegradable foaming composition, biodegradable foam using same, and foamed molded body

Abstract

The present invention relates to a biodegradable foaming composition, a biodegradable foam comprising the composition, and a foamed molded body. The biodegradable foam of the present invention has excellent properties, improved biodegradability, and enhanced fusion properties, and is thus suitable for moldability and appearance quality of a product. In addition, the biodegradable foam has excellent compressive strength and flexural strength and low thermal conductivity, thereby exhibiting high insulation properties.

Description

Biodegradable foam composition, biodegradable foam and foam molded article thereof

[0001] The present invention relates to a biodegradable foam composition, a biodegradable foam manufactured by including the composition, and a foam molded article thereof.

[0002] Foam acts as a cushioning agent for electronic devices, fresh produce like fruits and fish, and as an insulating packaging material for refrigerated and frozen foods. Polystyrene is the primary material used, though polypropylene has also been used recently. However, due to serious environmental pollution issues and regulations, interest in alternative materials to conventional foams is growing.

[0003] Among these alternatives, recycled paper and bio-derived resins are being used, but when they are damaged, the residual material flows into the soil or ocean, making recovery difficult and generating microplastics, making it difficult to fundamentally solve the problem.

[0004] Accordingly, numerous studies are being conducted to reduce environmental pollution, such as by using biodegradable materials instead of conventional non-degradable ones to reduce CO2 emissions. However, biodegradable materials have the disadvantages of being weaker and more expensive than non-degradable resins, and thus, not many commercially viable examples have been developed.

[0005] Polylactic acid (PLA) is a widely commercialized biodegradable resin. While it possesses excellent physical properties and processability, its brittleness limits its application. Research is underway to improve brittleness by adjusting the D-lactic acid content in PLA, but this approach has limitations, such as reduced physical properties. Furthermore, PLA is slow to biodegrade and decomposes only under certain composting conditions. Korean Patent Publication No. 10-2014-0017508 discloses a PLA-based foam, but its foaming rate is relatively low and its manufacturing process is complex. Therefore, there is a need to improve the physical properties and performance of the foam through modifications of PLA or blending of resins. In addition, Korean Patent Publication No. 10-2023-0032981 discloses a foaming composition that mixes PLA and polyhydroxyalkanoate (PHA), but there is a problem that physical properties are deteriorated due to the use of mainly amorphous polyhydroxyalkanoate (amorphous PHA), and therefore, research and development to solve this problem is urgently needed.

[0006] The present invention aims to solve the above-mentioned problems and other problems related thereto.

[0007] An exemplary object of the present invention is to provide a biodegradable foam composition having excellent physical properties and processability, and a biodegradable foam manufactured by including the composition.

[0008] Another exemplary object of the present invention is to provide a foamed molded article manufactured from the biodegradable foam.

[0009] The technical problem to be achieved according to the technical idea of ​​the invention disclosed in this specification is not limited to the problem to solve the above-mentioned problem, and other problems not mentioned will be clearly understood by those skilled in the art from the description below.

[0010] As one aspect for achieving the above purpose, one example of the present invention includes polylactic acid (PLA) and polyhydroxyalkanoate (PHA),

[0011] The above polyhydroxyalkanoate provides a biodegradable foaming composition comprising semi-crystalline polyhydroxyalkanoate (semi-crystalline PHA, scPHA) and amorphous polyhydroxyalkanoate (aPHA).

[0012] Another example of the present invention provides a biodegradable foam manufactured by including the biodegradable foam composition.

[0013] Another example of the present invention provides a foamed molded article manufactured by molding the biodegradable foam.

[0014] The biodegradable foam of the present invention possesses excellent physical properties and enhanced biodegradability. Its improved fusion properties make it suitable for product moldability and appearance quality. Furthermore, it possesses excellent compressive and flexural strengths and low thermal conductivity, resulting in high thermal insulation properties.

[0015] Meanwhile, the scope of the present invention is not limited by the effects described above.

[0016] Figure 1 is a scanning electron microscope image of a cross-section of a biodegradable foam according to an example of the present invention.

[0017] Figure 2 shows the flexural strength of a biodegradable foam according to an example of the present invention.

[0018] Figure 3 shows the compressive strength of a biodegradable foam according to an example of the present invention.

[0019] The present invention is specifically described as follows.

[0020] Meanwhile, each description and embodiment disclosed in this application can also be applied to each other description and embodiment. In other words, all combinations of the various elements disclosed in this application fall within the scope of this application. Furthermore, the scope of this application is not limited by the specific descriptions described below.

[0021] As one aspect for achieving the above purpose, the present invention includes polylactic acid (PLA) and polyhydroxyalkanoate (PHA),

[0022] The above polyhydroxyalkanoate (PHA) provides a biodegradable foaming composition comprising semi-crystalline polyhydroxyalkanoate (semi-crystalline PHA, scPHA) and amorphous polyhydroxyalkanoate (aPHA).

[0023] The above "polylactic acid (PLA)" is a widely commercialized biodegradable resin, but its application is limited due to its brittle nature, and it is known to have a slow biodegradation rate and to be decomposed only under certain composting conditions.

[0024] In one example of the present invention, the lactic acid, which is a monomer of the PLA, may be L-lactic acid, D-lactic acid, DL-lactic acid, a cyclic dimer (lactide), or a mixture of two or more thereof.

[0025] Preferably, the lactic acid monomer of the PLA may include 80 wt% or more of L-lactic acid and 20 wt% or less of D-lactic acid.

[0026] In one example of the present invention, when the PLA comprises L-lactic acid, D-lactic acid, DL-lactic acid, a cyclic dimer (lactide), or a mixture of two or more thereof as a monomer, the weight average molecular weight (Mw) of such PLA may be 10,000 g / mol or more, preferably 100,000 to 800,000 g / mol. The PLA comprising the monomer(s) may have a linear, branched, or other form, and the terminal hydroxyl group and carboxyl group may be substituted or modified with other functional groups, alkyl groups, or cyclic forms.

[0027] The above "polyhydroxyalkanoate (PHA)" is a thermoplastic natural polyester polymer that accumulates within microbial cells. It is a material that can be biodegraded in soil or marine conditions and has the advantage of a fast biodegradation rate, but may have problems with reduced mechanical properties and processability.

[0028] In one example of the present invention, the PHA may have one or more repeating units selected from the group consisting of 3-hydroxybutyrate (3-HB), 4-hydroxybutyrate (4-HB), 3-hydroxyvalerate (3-HV), and 3-hydroxyhexanoate (3-HHx).

[0029] For example, a polyhydroxyalkanoate (PHA) may comprise 3-hydroxybutyrate repeat units and 4-hydroxybutyrate repeat units.

[0030] The weight average molecular weight (Mw) of such PHA may be 10,000 g / mol or more, preferably 100,000 to 800,000 g / mol.

[0031] In the present invention, the semi-crystalline polyhydroxyalkanoate (semi-crystalline PHA, scPHA) exhibits a semi-crystalline characteristic by containing 4-HB repeating units in an amount of about 5 wt% or more and less than 15 wt%. In addition to the 4-HB repeating unit, the scPHA may additionally contain at least one selected from the group consisting of 3-HB repeating units, 3-HV repeating units, and 3-HHx repeating units in an amount of about 85 wt% or more and less than 95 wt%. For example, in addition to the 4-HB repeating unit, the scPHA may additionally contain 3-HB repeating units in an amount of about 85 wt% or more and less than 95 wt%.

[0032] In the present invention, the amorphous polyhydroxyalkanoate (aPHA) exhibits an amorphous characteristic by containing 15 wt% or more and 100 wt% or less, or 15 wt% or more and 50 wt% or less, of a 4-HB repeating unit. Such aPHA may additionally contain, in addition to the 4-HB repeating unit, at least one selected from the group consisting of a 3-HB repeating unit, a 3-HV repeating unit, and a 3-HHx repeating unit, in an amount of about 0 to 85 wt%. For example, in addition to the 4-HB repeating unit, the aPHA may additionally contain, in addition to the 4-HB repeating unit, a 3-HB repeating unit in an amount of about 0 to 85 wt%.

[0033] The composition of the present invention, which comprises scPHA and aPHA, each containing 4-HB repeating units, together with PLA in the aforementioned amounts, can improve physical properties such as mechanical strength of a foam and a foaming rate. In addition, a foam manufactured from such a composition can exhibit excellent mechanical properties such as inter-bead fusion properties, thermal conductivity, compressive strength, and flexural strength after molding.

[0034] It is preferable that the biodegradable foam composition according to the present invention comprises the above-described PLA, scPHA and aPHA.

[0035] In one embodiment of the present invention, the scPHA may be included in an amount of about 5 to 250 parts by weight, preferably about 10 to 110 parts by weight, and more preferably about 20 to 80 parts by weight, based on 100 parts by weight of PLA.

[0036] In one embodiment of the present invention, the aPHA may be included in an amount of about 5 to 250 parts by weight, preferably about 5 to 80 parts by weight, and more preferably about 10 to 50 parts by weight, based on 100 parts by weight of PLA.

[0037] In one embodiment of the present invention, the total content of the scPHA and aPHA may be about 10 to 500 parts by weight, preferably about 15 to 190 parts by weight, and more preferably about 30 to 130 parts by weight, based on 100 parts by weight of PLA.

[0038] In one embodiment of the present invention, the usage ratio (mixing ratio) of the PLA, scPHA, and aPHA may be 1:0.05 to 2.5:0.05 to 2.5 by weight, preferably 1:0.1 to 1.1:0.05 to 0.8 by weight, and more preferably 1:0.2 to 0.8:0.1 to 0.5 by weight.

[0039] The present invention can overcome the problems of reduced biodegradability, physical properties, and processability and brittleness of existing PLA and PHA by introducing a three-component composition containing the above-described scPHA, aPHA, and PLA in a specific content, and specifically, when the weight ratio content range of the three-component composition is satisfied, excellent effects of biodegradability, physical properties, and processability can be obtained. In particular, when the content of PLA is 100 parts by weight, when the content of scPHA is less than 5 parts by weight, there is a problem of reduced mechanical properties due to low crystallinity, and on the other hand, when the content of scPHA exceeds 250 parts by weight, there is a problem of low brittleness due to high crystallinity. In addition, when the amorphous material is above the glass transition temperature, it has flexibility and increases formability and fusion properties. However, when the content of aPHA is less than 5 parts by weight, there is a problem in that it does not have sufficient flexibility and thus cannot increase fusion properties. On the other hand, when the content of aPHA exceeds 250 parts by weight, there is a problem in that the amorphous region that increases flexibility in the material increases excessively, thereby lowering the mechanical properties.

[0040] In the present invention, the composition may further include an additive.

[0041] The above additive may be at least one selected from the group consisting of a chain extender, a nucleating agent, and an antistatic agent.

[0042] In the present invention, the chain extender may be an isocyanate-based, epoxy-based or anhydride-based agent.

[0043] As an example of the present invention, the isocyanate system may be methylene diphenyl diisocyanate or hexamethylene diisocyanate.

[0044] As an example of the present invention, the epoxy system may be a multifunctional epoxy-based styrene-acrylic oligomer.

[0045] As an example of the present invention, the anhydride system may be a pyromellitic dianhydride.

[0046] In the present invention, it is preferable to use the chain extender in an amount of 0.1 to 10.0 wt% based on the total content of the composition. If the content of the chain extender is less than 0.1 wt%, the chain extension reaction may not occur sufficiently, and on the other hand, if the content of the chain extender exceeds 10.0 wt%, an overreaction may occur.

[0047] In the present invention, the nucleating agent may be at least one selected from the group consisting of inorganic materials such as mica, talc, silica, calcium carbonate, and clay.

[0048] In the present invention, the nucleating agent may be at least one selected from the group consisting of organic materials such as cellulose fiber (including wood powder), zinc citrate, n-methylenedicarboxylic dibenzoylhydrazide, phenylphosphonic acid, zinc phenylphosphonate, orotic acid, uracil, potassium dimethyl sulfoisophthalate (potassium salt of 3,5-bis(methoxycarbonyl)benzenesulfonate, LAK-301), 4-tert-butylcalix, and calcium phenylmalonate.

[0049] The content of the above nucleating agent is not particularly limited, and may be, for example, about 0.1 to 10 wt% based on the total amount of the composition.

[0050] In the present invention, the antistatic agent may be anionic, nonionic or cationic.

[0051] As an example of the present invention, the anionic system may be a carboxylate system, a sulfonate system, a phosphophosphate system, or a phosphate system, and may be at least one selected from the group consisting of alkyl sulfonate, alkylbenzene sulfonate, α-olefin sulfonate, alkyl sulfate, and alkyl ether sulfate.

[0052] As an example of the present invention, the nonionic system may be a phenoloxyethylene ether or polyhydric alcohol fatty acid ester system, an alkynol amide system, a hydrophilic polymer system, and may be at least one selected from the group consisting of glycerol ester, ethoxylated sorbitan ester, alkoxylated fatty acid ester, ethoxylated amine, and stearyl diethanol amine.

[0053] As an example of the present invention, the cationic system may be a quaternary ammonium system, an alkyl amine sulfate series, and may be at least one selected from the group consisting of Di-(palm carboxyethyl) hydroxyethyl methyl ammonium methosulfate, Di-allyl di-methyl ammonium chloride, benzalkonium chloride, tri-ethanolamine alkyl sulfate, and oxyethylene alkyl amine sulfate.

[0054] The content of the antistatic agent is not particularly limited, and may be, for example, about 0.1 to 10 wt% based on the total amount of the composition.

[0055] In the present invention, the composition may further include other additives, and the other additives may be at least one selected from the group consisting of a reactive modifier, an antioxidant, an activator, a UV stabilizer, and a reinforcing agent, but are not limited thereto.

[0056] As an example of the present invention, the reactive modifier may be a radical-generating reactive modifier such as lauryl peroxide or dicumyl peroxide, or a graft reactive modifier such as maleic anhydride (MAH) or glycidyl methacrylate.

[0057] As an example of the present invention, the antioxidant may be a phenol-based antioxidant, a phosphorus-based antioxidant, a benzimidazole-based antioxidant, or an amine-based antioxidant.

[0058] In the present invention, the active agent is used to reduce the viscosity of the mixture and increase processability, and may be, for example, at least one selected from the group consisting of PE wax, paraffin wax, magnesium stearate, and calcium stearate.

[0059] In the present invention, any UV stabilizer commonly used in the art can be used without limitation as the UV stabilizer.

[0060] In the present invention, the reinforcing material may be at least one selected from the group consisting of cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cellulose fiber, rayon fiber, flax fiber, carbon fiber, glass fiber, nanoclay, lignin, graphen, calcium carbonate, barium sulfate, and mica.

[0061] In the present invention, the other additives may be included in an amount of 0.1 to 5.0 wt% based on the total content of the composition. If the content of the other additives is less than 0.1 wt%, the additive effect may be insufficient, and on the other hand, if the content of the other additives exceeds 5.0 wt%, overreacted or unreacted products may occur.

[0062] As another aspect for achieving the above object, the present invention provides a biodegradable foam comprising the biodegradable foam composition. Here, the biodegradable foam means a foamed product of the biodegradable foam composition.

[0063] In the present invention, the independent cell ratio of the biodegradable foam may be 80% or more, 85% or more, 90% or more, or 95% or more. If the independent cell ratio of the biodegradable foam is low, such as less than 80%, the mechanical properties of the foam may deteriorate, and problems such as shrinkage in the appearance may occur due to insufficient air retention inside the foam.

[0064] As another aspect for achieving the above object, the present invention provides a foamed molded article manufactured by molding the biodegradable foam.

[0065] In one embodiment of the present invention, the forming may be heat forming, pressure forming or steam forming, and preferably steam forming.

[0066] In the present invention, the density of the foamed molded body is about 0.05 g / cm 3 Less than or about 0.04 g / cm 3 It may be less than or equal to about 0.01 g / cm 3 or more than or about 0.02 g / cm 3 It can be ideal. The density of the molded body is about 0.04 g / cm 3 If it is lower than this, it has the advantage of being light and is economical because less raw materials are used to manufacture the molded body.

[0067] In the present invention, the thermal conductivity of the foamed molded body may be about 0.04 W / mk or less, specifically about 0.035 W / mk or less, more specifically about 0.03 W / mk or less, and the lower limit is meaningless in terms of the purpose of lowering the numerical value of the thermal conductivity, but may be about 0.01 W / mk or more.

[0068] If the thermal conductivity of the foam molded body exceeds approximately 0.04 W / mk, the insulation may not be properly provided when used as a food packaging material, which may result in a reduction in the cooling function.

[0069] In the present invention, the flexural strength of the foam molded body may be about 0.2 MPa or more, about 0.3 MPa or more, or about 0.4 MPa or more, and may be about 1.5 MPa or less. If the flexural strength of the foam molded body is high, there is an advantage in that the foam molded body manufactured as a packaging material can withstand a high load. In particular, when the flexural strength of the foam molded body is about 0.2 MPa or more, it can withstand a load similar to that of existing non-degradable packaging materials.

[0070] In the present invention, the compressive strength of the foam molded body may be about 0.1 MPa or more, about 0.2 MPa or more, or about 0.3 MPa or more, and may be about 1.5 MPa or less. If the compressive strength of the foam molded body is high, it may affect the mechanical properties, similar to the flexural strength, and may also help improve the insulation properties by making the space between the foams denser. In particular, if the compressive strength of the foam molded body is about 0.1 MPa or more, it may have properties similar to those of existing non-degradable packaging materials.

[0071] As another aspect for achieving the above object, the present invention provides a method for producing a biodegradable foam, comprising the step of mixing PLA, scPHA and aPHA to obtain a foaming composition.

[0072] The above PLA, PHA, foaming composition and biodegradable foam are as described above.

[0073] In one embodiment of the present invention, in the manufacturing method, the scPHA may be mixed in an amount of about 5 to 250 parts by weight, preferably about 10 to 110 parts by weight, and more preferably about 20 to 80 parts by weight, based on 100 parts by weight of PLA.

[0074] In one embodiment of the present invention, in the manufacturing method, the aPHA may be mixed in an amount of about 5 to 250 parts by weight, preferably about 5 to 80 parts by weight, and more preferably about 10 to 50 parts by weight, based on 100 parts by weight of PLA.

[0075] In one embodiment of the present invention, the total content of the scPHA and aPHA may be about 10 to 500 parts by weight, preferably about 15 to 190 parts by weight, and more preferably about 30 to 130 parts by weight, based on 100 parts by weight of PLA.

[0076] In one embodiment of the present invention, the usage ratio (mixing ratio) of the PLA, scPHA, and aPHA may be 1:0.05 to 2.5:0.05 to 2.5 by weight, preferably 1:0.1 to 1.1:0.05 to 0.8 by weight, and more preferably 1:0.2 to 0.8:0.1 to 0.5 by weight.

[0077] In the present invention, the manufacturing method may further include a step of adding an additive. The additive is as described above.

[0078] In the present invention, the manufacturing method may further include a step of adding other additives. The other additives are as described above.

[0079] In the present invention, after obtaining the foaming composition as described above, the process of foaming the foaming composition can be performed by autoclave foaming, steam foaming, or extrusion foaming according to any purpose.

[0080] Conventional foam manufacturing methods utilize chemical foaming agents. This process generates a gas that foams polymers using a chemical method. The chemical foaming agent added to the plastic is heated to foam, decomposing the gas and causing foaming. Furthermore, chemical interactions between polymer components can be utilized, with the gas released by the reaction being utilized to generate foam. Typically, chemical foaming involves a crosslinking process simultaneously, resulting in small, uniform cells and excellent physical properties. However, the crosslinking process results in irreversible properties, making recycling impossible. Furthermore, the foaming process using chemical foaming agents generates byproducts, creating hazardous substances and requiring equipment to remove them.

[0081] On the other hand, the physical foaming method to be performed in the present invention is a process in which gases such as CO2 and N2 and supercritical fluids are dissolved and dispersed in a polymer, bubble nuclei are formed, and bubbles grow and stabilize, and has the advantage of being able to use harmless gases and evenly distribute bubbles.

[0082] The extrusion foaming method, which is one of the foaming methods that can be performed in the present invention, is composed of a step of mixing a biodegradable resin and a step of foaming as one continuous step, so that productivity is improved, deviations occur less each time it is manufactured, and the size of the foam can be controlled according to the shape design of the substrate (die).

[0083] As another aspect for achieving the above object, the present invention provides a method for producing a foamed molded article, comprising a step of molding a biodegradable foam manufactured according to the above manufacturing method.

[0084] The molding process of the above foam may be thermoforming, pressure molding or steam molding, and steam molding is preferred because it is easy to mold.

[0085] In the present invention, the steam forming can be performed by applying pressure to the biodegradable foam.

[0086]

[0087] Hereinafter, the present invention will be described in more detail through the following examples. However, these examples are intended to exemplify the present invention and the scope of the present invention is not limited to these examples.

[0088] Examples 1 to 8 and Comparative Examples 1 to 8

[0089] Polylactic acid (PLA, PLA2003D, NatureWorks), semi-crystalline polyhydroxyalkanoate (semi-crystalline PHA, scPHA) poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (containing 5 to 15 wt% of 4-hydroxybutyrate, CJ CheilJedang), amorphous polyhydroxyalkanoate (aPHA) poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (containing 15 to 50 wt% of 4-hydroxybutyrate, CJ CheilJedang), epoxy chain extender (Joncryl TM ADR 4368), inorganic talc as a nucleating agent and alkyl sulfonate as a static adhesive were prepared.

[0090] The raw materials prepared with the compositions and composition ratios shown in Tables 1 and 2 below were loaded into an extrusion foaming device, melted, mixed, and compounded, and high-pressure gas was injected into the mixing area, mixed, and passed through a die to manufacture foams of Examples 1 to 8 and Comparative Examples 1 to 8. In Tables 1 and 2 below, the content unit of each component is part by weight, based on 100 parts by weight of PLA.

[0091] Classification Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Composition PLA 100 100 100 100 100 100 100 100 sc PHA 20 20 20 50 60 80 80 80 a PHA 13.31 3.31 3.35 0 40 20 20 20 Chain extender 1.31 31 34 6666 Nucleating agent 01.31 3000 22 Antistatic agent 00 1.30000 2

[0092] ClassificationComparison Example 1Comparison Example 2Comparison Example 3Comparison Example 4Comparison Example 5Comparison Example 6Comparison Example 7Comparison Example 8CompositionPLA100100100100100100100100100scPHA000033.301000aPHA0000033.30100Chain Extender01111.31.366Nucleating Agent00110000Antistatic Agent00010000

[0093]

[0094] Experimental Example 1: Analysis of Foam Properties

[0095] The physical properties of the foams (bead foams) of Examples 1 to 8 and Comparative Examples 1 to 8 were analyzed.

[0096] Specifically, the density of each foam was measured using a hydrometer, the diameter was measured using a vernier caliper, and the independent cell percentage was measured using a gas pycnometer (Ultrapyc 5000 Foam, Anton Paar).

[0097] As a result, as shown in Tables 3 and 4, the independent bubble ratio was found to be significantly higher in the case where all of PLA, scPHA, and aPHA were contained (Examples 1 to 8), compared to the case where neither scPHA nor aPHA was contained (Comparative Examples 1 to 4), or when only one of the two was contained (Comparative Examples 5 to 8).

[0098] Classification Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Bead foam density (g / cm) 3 )0.0350.0350.0350.060.050.040.040.04Diameter (mm)444444444Independent cell ratio (%)8090908080859090

[0099] Comparison Example 1 Comparison Example 2 Comparison Example 3 Comparison Example 4 Comparison Example 5 Comparison Example 6 Comparison Example 7 Comparison Example 8 Bead Foam Density (g / cm) 3 )0.060.040.0350.0350.0350.060.040.08Diameter (mm)444444443Independent bubble ratio (%)7080909085709050

[0100] Figure 1 shows the results of observing the cross-section of the foam of Example 3 using a scanning electron microscope, and as shown in Figure 1, the foam had a high independent cell ratio.

[0101] In this way, when the foam has a high independent cell ratio, sufficient air is contained inside the foam, so that the appearance is tight and good, and the mechanical strength can be increased when molded.

[0102]

[0103] Experimental Example 2: Analysis of Molded Foam Properties

[0104] To evaluate the formability and mechanical properties of the bead foam foams of Examples 1 to 8 and Comparative Examples 1 to 8, they were steam-molded into hexahedrons and then analyzed for their properties. The results of each analysis are shown in Tables 5 and 6 below.

[0105] (1) Density

[0106] The density of the molded foam was calculated by measuring the volume and weight of the cube.

[0107] (2) Thermal conductivity

[0108] Thermal conductivity was measured according to KS L 9016, the method for measuring thermal conductivity of insulating materials.

[0109] (3) Bead fusion

[0110] Bead fusion was evaluated by visually observing the interface between bead forms on the surface as follows.

[0111] - Good (○): The boundary between the bead foams on the surface of the molding foam is hardly observed and the surface condition is good.

[0112] - Insufficient (△): The boundary between the bead forms is observed on the surface of the molded form, but is not noticeable.

[0113] - Defective (X): The boundary between the bead forms on the surface of the molded form is significantly observed and the surface condition is poor.

[0114] (4) Flexural strength

[0115] Flexural strength was tested according to KS M ISO 1209, Method for measuring flexural properties of rigid foam plastics.

[0116] (5) Compressive strength

[0117] Compressive strength was calculated by compressing a test specimen of 100 mm in length, 100 mm in width, and 50 mm in thickness according to ASTM D1621 until the specimen was deformed by 13% of its original thickness, and dividing the load at 10% deformation by the initial horizontal cross-sectional area of ​​the test specimen.

[0118] Classification Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Molding foam density (g / cm) 3 )0.040.040.040.080.050.050.050.05Thermal Conductivity (W / mk)0.0350.0320.0230.0400.0380.0330.0300.025Bead Fusion ○○○○○○○○Flexural Strength (Mpa)0.240.330.320.260.340.380.420.44Compressive Strength (Mpa)0.140.190.190.150.170.190.220.22

[0119] Comparison Example 1 Comparison Example 2 Comparison Example 3 Comparison Example 4 Comparison Example 5 Comparison Example 6 Comparison Example 7 Comparison Example 8 Molding Foam Density (g / cm) 3 )0.080.050.040.040.040.080.050.10Thermal Conductivity (W / mk)0.0360.0360.0350.0260.0330.0410.0310.046Bead Adhesion XX△△△○△○Flexural Strength (Mpa)0.200.250.320.300.420.190.480.16Compressive Strength (Mpa)0.120.160.180.190.220.110.250.09

[0120] For reference, the results comparing the flexural strengths of Comparative Example 1, Example 3, and Example 8 are shown in Fig. 2, and the results comparing the compressive strengths of Comparative Example 1, Example 3, and Example 8 are shown in Fig. 3.

[0121] As can be seen in Table 3 and Fig. 2, when both scPHA and aPHA were included (Examples 1 to 8), the bead fusion properties were superior compared to when neither scPHA nor aPHA was included (Comparative Examples 1 to 4) or when only one of the two was included (Comparative Examples 5 and 7). In addition, when both scPHA and aPHA were included (Examples 1 to 8), the flexural strength and compressive strength were significantly higher compared to Comparative Examples 6 and 8, in which the bead fusion properties were relatively good.

[0122] In the case of Examples 1 to 8, the bead fusion properties were all good, and the flexural strength was 0.2 MPa or more and the compressive strength was 0.1 MPa or more, confirming that the foam had excellent properties.

[0123]

[0124] From the above description, those skilled in the art will understand that the present invention can be implemented in other specific forms without altering its technical spirit or essential characteristics. In this regard, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. The scope of the present invention should be interpreted as encompassing all changes or modifications derived from the meaning and scope of the following claims and their equivalent concepts, rather than the detailed description above.

Claims

1. Contains polylactic acid (PLA) and polyhydroxyalkanoate (PHA). A biodegradable foaming composition, wherein the polyhydroxyalkanoate comprises a semi-crystalline polyhydroxyalkanoate (semi-crystalline PHA) and an amorphous polyhydroxyalkanoate (amorphous PHA).

2. In paragraph 1, A biodegradable foam composition, wherein the semi-crystalline polyhydroxyalkanoate is contained in an amount of 5 to 250 parts by weight based on 100 parts by weight of polylactic acid.

3. In paragraph 1, A biodegradable foam composition, wherein the amorphous polyhydroxyalkanoate is contained in an amount of 5 to 250 parts by weight based on 100 parts by weight of polylactic acid.

4. In paragraph 1, A biodegradable foam composition, wherein the total content of the semi-crystalline polyhydroxyalkanoate and the amorphous polyhydroxyalkanoate is in the range of 50 to 500 parts by weight based on 100 parts by weight of polylactic acid.

5. In paragraph 1, The above semi-crystalline polyhydroxyalkanoate contains 4-hydroxybutyrate (4-HB) repeating units in an amount of 5 wt% or more and less than 15 wt% based on the total amount of all repeating units, A biodegradable foam composition, wherein the amorphous polyhydroxyalkanoate comprises 15 wt% or more and 100 wt% or less of 4-hydroxybutyrate (4-HB) repeating units based on the total amount of all repeating units.

6. In paragraph 1, The above composition further comprises an additive, A biodegradable foam composition, wherein the additive is at least one selected from the group consisting of a chain extender, a nucleating agent, an antistatic agent, a reactive modifier, an antioxidant, a lubricant, a UV stabilizer, and a reinforcing agent.

7. A biodegradable foam of a biodegradable foam composition according to any one of claims 1 to 6.

8. In paragraph 7, A biodegradable foam having an independent cell ratio of 80% or more.

9. A foam molded article manufactured by molding the biodegradable foam of Article 7.

10. In paragraph 9, The density of the above foam molded body is 0.05 g / cm 3 Below, foam molded body.

11. In paragraph 9, The above foam molded body is a foam molded body having a thermal conductivity of 0.04 W / mk or less.

12. In paragraph 9, A foam molded body having a flexural strength of 0.2 MPa or more and a compressive strength of 0.1 MPa or more.

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