Polypropylene resin composition for foam injection molding and foam-molded article prepared therefrom

Abstract

The polypropylene resin composition for foam injection molding according to the present invention is characterized by comprising: about 100 parts by weight of a base resin comprising about 15-65% by weight of a high-melt-strength polypropylene resin and about 35-85% by weight of a block polypropylene resin; about 1.5-4.5 parts by weight of zinc oxide; and about 0.1-1.5 parts by weight of a zinc organic compound. The polypropylene resin composition for foam injection molding has excellent thermal insulation, antibacterial properties, surface durability, and lightweight properties, and an excellent balance of said properties.

Description

Polypropylene resin composition for foam injection molding and foam molded body produced therefrom

[0001] The present invention relates to a polypropylene resin composition for foam injection molding and a foamed molded article manufactured therefrom. More specifically, the present invention relates to a polypropylene resin composition for foam injection molding having excellent thermal insulation, antibacterial properties, surface durability, lightweight properties, and a balance of these physical properties, and a foamed molded article manufactured therefrom.

[0002]

[0003] Typically, since thermoplastic resins lack thermal insulation properties, when thermoplastic resin compositions are applied to internal parts (injection molded products) of appliances such as refrigerators and air conditioners that require thermodynamic cycles, insulating materials such as expanded polystyrene (EPS) and expanded polypropylene (EPP) are attached for use.

[0004] However, when insulating materials are added to existing thermoplastic resin composition products, product production costs increase due to additional material costs and increased manufacturing time associated with the processing steps, and recycling is not easy due to the use of different materials.

[0005] Furthermore, although insulation material manufacturing technologies involving the foaming of thermoplastic resins such as EPS and EPP using chemical foaming agents are widely used commercially, they suffer from low productivity due to the need for compression molding, limitations on manufacturing only plate-shaped products, and difficulties in application to injection molding technology. Moreover, since these materials have a uniform foam structure both internally and on the surface and possess low specific gravity, their surface durability is very poor, making them difficult to apply in various fields and requiring separate surface coatings and protective films.

[0006] In addition, the importance and interest in antibacterial properties are emerging regarding internal components of refrigerators and air conditioners.

[0007] Therefore, there is a need to develop polypropylene resin compositions with excellent thermal insulation, antibacterial properties, surface durability, lightweight properties, and a balance of these physical properties.

[0008] The background technology of the present invention is disclosed in Korean Patent Publication No. 10-2014-0009470, etc.

[0009]

[0010] The objective of the present invention is to provide a polypropylene resin composition for foam injection molding that has excellent thermal insulation, antibacterial properties, surface durability, lightweight properties, and a balance of these physical properties.

[0011] Another objective of the present invention is to provide a foamed molded article formed from the above-described polypropylene resin composition for foam injection molding.

[0012] Another objective of the present invention is to provide a method for manufacturing the foamed molded body.

[0013] The above and other objectives of the present invention can all be achieved by the present invention described below.

[0014]

[0015] 1. One aspect of the present invention relates to a polypropylene resin composition for foam injection. The polypropylene resin composition for foam injection comprises about 100 parts by weight of a base resin comprising about 15 to about 65 parts by weight of a high melt strength polypropylene resin and about 35 to about 85 parts by weight of a block polypropylene resin; about 1.5 to about 4.5 parts by weight of zinc oxide; and about 0.1 to about 1.5 parts by weight of a zinc organic compound.

[0016] 2. In the above 1 embodiment, the high melt strength polypropylene resin may have a melt strength of about 25 to about 45 cN as measured by Rheotens equipment.

[0017] 3. In the above 1 or 2 embodiments, the high melt strength polypropylene resin may have a melt-flow index of about 0.1 to about 10 g / 10 min, measured at 230°C and a 2.16 kg load according to ASTM D1238.

[0018] 4. In the above 1 to 3 embodiments, the block polypropylene resin may be a block polypropylene resin composed of one or more of a homopolypropylene block, an ethylene-propylene copolymer block, and a homopolyethylene block.

[0019] 5. In the above 1 to 4 embodiments, the block polypropylene resin may have a melt-flow index of about 0.1 to about 5 g / 10 min measured at 230°C and a 2.16 kg load according to ASTM D1238.

[0020] 6. In the above 1 to 5 embodiments, the zinc organic compound may include one or more of zinc acetylacetonate and zinc acetate.

[0021] 7. In the above 1 to 6 embodiments, the weight ratio of the zinc oxide and the zinc organic compound may be about 1:0.04 to about 1:0.5.

[0022] 8. In the above 1 to 7 embodiments, the polypropylene resin composition for foam injection molding may have a thermal conductivity of about 0.04 to about 0.06 W / m·K of a foam injection molded specimen measuring 24.6 cm × 24.6 cm × 2 cm as measured according to KS M 3809.

[0023] 9. In the above 1 to 8 embodiments, the polypropylene resin composition for foam injection molding may have an antibacterial activity value of approximately 2 to approximately 7, measured after inoculating a 5 cm × 5 cm specimen with Staphylococcus aureus and Escherichia coli according to the JIS Z 2801 antibacterial evaluation method and culturing for 24 hours at 35°C and RH 90%.

[0024] 10. In the above 1 to 9 embodiments, the polypropylene resin composition for foam injection molding may have a total surface impact energy of about 3 to about 10 J for a foam injection molded specimen of size 10 cm × 10 cm × 2 cm measured under 5 kg, 1 m conditions according to ASTM D1709.

[0025] 11. In the above 1 to 10 embodiments, the polypropylene resin composition for foam injection molding may have a specific gravity of about 0.05 to about 0.5 calculated according to Formula 1 below:

[0026] [Equation 1]

[0027] Specific gravity = Weight of specimen / Weight of specimen submerged in water

[0028] In the above Equation 1, the specimen weight is the weight of a foam injection molded specimen with dimensions of 3 cm × 3 cm × 2 cm, and the submerged specimen weight is the weight measured when the foam injection molded specimen is completely submerged in water.

[0029] 12. Another aspect of the present invention relates to a foamed molded article. The foamed molded article is formed by physically foaming a polypropylene resin composition for foam injection according to any one of 1 to 11 using a core-back method, and is characterized by comprising a first non-foamed surface layer, an internal foamed layer, and a second non-foamed surface layer.

[0030] 13. In the above 12 embodiments, the first surface layer and the second surface layer may each have a thickness of about 0.3 to about 0.7 mm.

[0031] 14. In the above 12 or 13 embodiments, the internal foam layer may have a thickness of about 9 to about 40 mm.

[0032] 15. Another aspect of the present invention relates to a method for manufacturing a foamed molded article. The manufacturing method comprises the step of: placing a polypropylene resin composition for foam injection according to any one of 1 to 11 into a mold of a physical foam injection machine; and injecting nitrogen as a foaming gas into the mold, and, under conditions of a foaming gas pressure of about 80 to about 240 bar, a cylinder temperature of about 200 to about 230°C, and a mold temperature of about 60 to about 90°C, applying a holding pressure of 300 bar for about 2 to about 10 seconds, and then proceeding the core back about 9 to about 40 mm.

[0033]

[0034] The present invention has the effect of providing a polypropylene resin composition for foam injection molding that has excellent thermal insulation, antibacterial properties, surface durability, lightweight properties, and a balance of these physical properties, a foamed molded article produced therefrom, and a method for producing said foamed molded article.

[0035]

[0036] FIG. 1 is a schematic diagram schematically illustrating a cross-section of a foamed molded body according to one embodiment of the present invention.

[0037]

[0038] The present invention will be described in detail below.

[0039] The polypropylene resin composition for foam injection according to the present invention is formed from a thermoplastic resin composition comprising (A) a high melt strength polypropylene resin; (B) a block polypropylene resin; (C) zinc oxide; and (D) a zinc organic compound.

[0040] In this specification, "a to b" indicating a numerical range is defined as "≥a and ≤b".

[0041]

[0042] (A) High melt strength polypropylene resin

[0043] A high melt strength (HMS) polypropylene resin according to one embodiment of the present invention can be applied together with block polypropylene resin, zinc oxide, zinc organic compounds, etc., to improve the thermal insulation, antibacterial properties, surface durability, lightness, and balance of physical properties of a polypropylene resin composition for foam injection and a foam molded article, and can use a high melt strength polypropylene resin used in a conventional polypropylene resin composition for foam injection.

[0044] In a specific example, the high melt strength polypropylene resin is a polypropylene modified by introducing a long chain branch structure to the polypropylene backbone, and is a polypropylene resin in which the melt strength is increased due to the long chain structure and the tensile strength, flexural strength, and flexural modulus are improved.

[0045] In a specific example, the high melt tension polypropylene resin may have a melt tension of about 25 to about 45 cN, for example, about 30 to about 40 cN, as measured by a Rheotens device (a Rheotens 71.97 device from Geppert, Germany). Within this range, the foaming characteristics and foam cell stability of the polypropylene resin composition for foam injection molding may be excellent. Here, the melt tension can be measured by feeding the resin into a Brabender uniaxial extruder from Brabender, Germany, extruding it at 200°C and 50 rpm, and mounting the Rheotens device below the die. The Rheotens device is equipped with four wheels for stretching the resin, and the stretching speed is equal (0.1 s⁻¹). -1 It is accelerated uniformly by ).

[0046] In a specific example, the high melt strength polypropylene resin may have a melt-flow index of about 0.1 to about 10 g / 10 min, for example, about 0.5 to about 5 g / 10 min, measured according to ASTM D1238 under conditions of 230°C and a 2.16 kg load. Within this range, the moldability and foaming characteristics of the polypropylene resin composition for foam injection molding may be excellent.

[0047] In a specific example, the high melt strength polypropylene resin may be included in an amount of about 15 to about 65 weight%, for example, about 20 to about 60 weight%, of a base resin comprising a high melt strength polypropylene resin and a block polypropylene resin, in 100 weight% of the base resin. If the content of the high melt strength polypropylene resin is less than about 15 weight% of the 100 weight% of the base resin, there is a risk that the thermal insulation, foaming characteristics, foam cell stability, etc. of the polypropylene resin composition for foam injection and the foam molded article will be reduced, and if it exceeds about 65 weight%, there is a risk that the surface durability, impact resistance, etc. of the polypropylene resin composition for foam injection and the foam molded article will be reduced.

[0048]

[0049] (B) Block polypropylene resin

[0050] A block polypropylene resin according to one embodiment of the present invention can be applied together with a high melt strength polypropylene resin, zinc oxide, and a zinc organic compound, etc., to improve the thermal insulation, antibacterial properties, surface durability, lightness, and balance of physical properties of a polypropylene resin composition for foam injection and a foam molded article, and a block polypropylene resin applied to a conventional thermoplastic resin composition can be used.

[0051] In a specific example, the block polypropylene resin may be a block polypropylene resin composed of a homopolypropylene block, an ethylene-propylene copolymer block, and / or a homopolyethylene block.

[0052] In a specific example, the polypropylene resin may have a melt-flow index of about 0.1 to about 5 g / 10 min, for example, about 0.2 to about 3 g / 10 min, measured according to ASTM D1238 under conditions of 230°C and a 2.16 kg load. Within this range, the mechanical strength, moldability, foaming characteristics, etc. of the polypropylene resin composition for foam injection can be excellent.

[0053] In a specific example, the block polypropylene resin may be included in an amount of about 35 to about 85 weight%, for example, about 40 to about 80 weight%, of a base resin comprising a high melt strength polypropylene resin and a block polypropylene resin, in 100 weight% of the base resin. If the content of the block polypropylene resin is less than about 35 weight% of the base resin, there is a risk that the surface durability, impact resistance, etc. of the polypropylene resin composition for foam injection and the foam molded article will be reduced, and if it exceeds about 85 weight%, there is a risk that the thermal insulation, foaming characteristics, foam cell stability, etc. of the polypropylene resin composition for foam injection and the foam molded article will be reduced.

[0054]

[0055] (C) Zinc oxide

[0056] Zinc oxide according to one embodiment of the present invention can be applied together with high melt strength polypropylene resin, block polypropylene resin, zinc organic compound, etc., to improve the thermal insulation, antibacterial properties, surface durability, lightness, and balance of physical properties of the foam injection polypropylene resin composition and foam molded article, and zinc oxide applied to conventional thermoplastic resin compositions can be used.

[0057] In a specific example, the zinc oxide may have an average particle size (D50) of about 0.1 to about 10 μm, for example, about 0.1 to about 5 μm, measured using a particle size analyzer (Beckman Coulter, Laser Diffraction Particle Size Analyzer LS I3 320). Additionally, the zinc oxide may have a specific surface area BET of about 1 to about 15 m², measured using a BET analysis instrument (Micromeritics, Surface Area and Porosity Analyzer ASAP 2020) by the nitrogen gas adsorption method. 2 / g, for example, about 1 to about 12 m 2 It may be / g, and the purity may be 99% or higher. Within the above range, the antibacterial properties, foamability, foam moldability, etc. of the polypropylene resin composition for foam injection and the foam molded article may be excellent.

[0058] In a specific example, the zinc oxide may be included in an amount of about 1.5 to about 4.5 parts by weight, for example, about 1.9 to about 3.8 parts by weight, with respect to about 100 parts by weight of the base resin. If the content of the zinc oxide is less than about 1.5 parts by weight with respect to about 100 parts by weight of the base resin, there is a risk that the antibacterial properties of the polypropylene resin composition for foam injection and the foam molded article will be reduced, and if it exceeds about 4.5 parts by weight, there is a risk that the thermal insulation properties of the polypropylene resin composition for foam injection and the foam molded article will be reduced.

[0059]

[0060] (D) Zinc organic compounds

[0061] A zinc organic compound according to one embodiment of the present invention can be applied together with high melt strength polypropylene resin, block polypropylene resin, zinc oxide, etc., to improve the thermal insulation, antibacterial properties, surface durability, lightness, and balance of physical properties of a polypropylene resin composition for foam injection and a foam molded article, and a zinc organic compound used in a conventional thermoplastic resin composition can be used.

[0062] In a specific example, the zinc organic compound may include one or more of zinc acetylacetonate and zinc acetate. For example, it may include zinc acetylacetonate or zinc acetate.

[0063] In a specific example, the zinc organic compound may be included in an amount of about 0.1 to about 1.5 parts by weight, for example, about 0.3 to about 1.2 parts by weight, with respect to about 100 parts by weight of the base resin. If the content of the zinc organic compound is less than about 0.1 parts by weight with respect to about 100 parts by weight of the base resin, there is a risk that the thermal insulation, foaming characteristics, foam cell stability, etc. of the polypropylene resin composition for foam injection and the foam molded article will be reduced, and if it exceeds about 1.5 parts by weight, there is a risk that the surface durability, injection moldability, appearance characteristics, etc. of the polypropylene resin composition for foam injection and the foam molded article will be reduced.

[0064] In a specific example, the weight ratio of the zinc oxide and the zinc organic compound may be about 1:0.04 to about 1:0.5, for example, about 1:0.05 to about 1:0.4, for example, about 1:0.07 to about 1:0.33. Within the above range, the thermal insulation, surface durability, and balance of physical properties of the polypropylene resin composition for foam injection and the foam molded article may be superior.

[0065]

[0066] A polypropylene resin composition for foam injection molding according to one embodiment of the present invention may further include additives used in conventional polypropylene resin compositions to a extent that does not impede the purpose and effects of the present invention. Examples of said additives include, but are not limited to, compatibilizers, antioxidants, impact modifiers, flame retardants, anti-dripping agents, release agents, nucleating agents, UV stabilizers, pigments, dyes, and mixtures thereof.

[0067] In a specific example, the above-mentioned compatibilizer may be a modified polyolefin, but is not limited thereto.

[0068] In a specific example, when using the above additive, the content may be about 0.001 to about 40 parts by weight, for example about 0.1 to about 10 parts by weight, with respect to about 100 parts by weight of the base resin, but is not limited thereto.

[0069]

[0070] A polypropylene resin composition for foam injection according to one embodiment of the present invention may be in the form of pellets produced by mixing the above components and melt-extruding them using a conventional twin-screw extruder at about 180 to about 250°C, for example, about 200 to about 230°C.

[0071] In a specific example, the above-described polypropylene resin composition for foam injection molding may have a thermal conductivity of about 0.04 to about 0.06 W / m·K, for example, about 0.045 to about 0.055 W / m·K, of a foam injection molded specimen (foam molded specimen) measuring 24.6 cm × 24.6 cm × 2 cm as measured according to KS M 3809.

[0072] In a specific example, the above-described polypropylene resin composition for foam injection molding may have an antibacterial activity value of approximately 2 to approximately 7 days, measured after inoculating a 5 cm × 5 cm specimen with Staphylococcus aureus and Escherichia coli according to the JIS Z 2801 antibacterial evaluation method and culturing for 24 hours at 35°C and RH 90%.

[0073] In a specific example, the polypropylene resin composition for foam injection molding may have a total face impact energy of about 3 to about 10 J, for example, about 4 to about 9 J, of a foam injection molded specimen measuring 10 cm × 10 cm × 2 cm under conditions of 5 kg, 1 m in accordance with ASTM D1709.

[0074] In a specific example, the polypropylene resin composition for foam injection molding may have a specific gravity calculated according to Formula 1 below of about 0.05 to about 0.5, for example, about 0.08 to about 0.4.

[0075] [Equation 1]

[0076] Specific gravity = Weight of specimen / Weight of specimen submerged in water

[0077] In the above Equation 1, the specimen weight is the weight of a foam injection specimen (foam molded specimen) with dimensions of 3 cm × 3 cm × 2 cm, and the submerged specimen weight is the weight measured when the foam injection specimen is completely submerged in water.

[0078]

[0079] The foamed molded article according to the present invention can be formed by physically foaming the above-described polypropylene resin composition for foam injection using a core-back method, and can be easily manufactured by a person with ordinary knowledge in the field to which the present invention belongs. Since the foamed molded article has excellent thermal insulation, antibacterial properties, surface durability, lightness, and a balance of these physical properties, it can be used for purposes such as injection-molded parts to prevent condensation in air circulation components of home appliances such as refrigerators and air conditioners, sound-absorbing and sound-insulating materials for reducing noise in dishwashers, and antibacterial materials.

[0080] FIG. 1 is a schematic diagram illustrating a cross-section of a foamed molded body according to one embodiment of the present invention. In the drawings, the sizes of the components constituting the invention are exaggerated for clarity of the specification and are not limited thereto. In addition, the shape of each component is not limited to the drawings and may have various shapes. As shown in FIG. 1, the foamed molded body (100) formed by physical foaming injection of the polypropylene resin composition for foaming injection using a core-back method is formed of the same material and may include an upper non-foamed first surface layer (112), an internal foamed layer (120) that foams inside, and a lower non-foamed second surface layer (114).

[0081] In a specific example, the first surface layer (112) and the second surface layer (114) are upper and lower surface portions that are not foamed during the core-bag type physical foam injection molding, and each may have a thickness of about 0.3 to about 0.7 mm. Within this range, the surface durability and antibacterial properties of the foamed molded body may be excellent.

[0082] In a specific example, the inner foam layer (120) is a part that forms a foam cell by foaming inside (between the first surface layer (112) and the second surface layer (114)) when the polypropylene resin composition for foam injection is physically foamed in a core-back manner. The thickness of the inner foam layer (120) can be adjusted according to the physical foam injection conditions and the core-back conditions, and the thickness of the inner foam layer (120) may be about 9 to about 40 mm. Within this range, the thermal insulation, lightness, sound absorption, etc. of the foamed molded body may be excellent.

[0083] In a specific example, the internal foam layer (120) may have an average size of foam cells ranging from about 20 to about 400 μm. Within this range, the thermal insulation, lightness, sound absorption, etc., of the foam molded body may be excellent. Here, the average size of the foam cells is a value obtained by cutting a cross-section, measuring the cell diameter (size) of the internal foam layer (120) at least 50 times using a Scanning Electron Microscope (SEM), and then calculating the average value.

[0084]

[0085] A foamed molded body according to one embodiment of the present invention can be manufactured by a manufacturing method comprising the step of: placing the polypropylene resin composition for foam injection into the mold of a physical foam injection machine; and injecting nitrogen as a foaming gas into the mold, and, under conditions of a foaming gas pressure of about 80 to about 240 bar, a cylinder temperature of about 200 to about 230°C, and a mold temperature of about 60 to about 90°C, applying a holding pressure of 300 bar for about 2 to about 10 seconds, and then advancing the core bag by about 9 to about 40 mm.

[0086]

[0087] The present invention is to be explained more specifically through the following examples, but these examples are for illustrative purposes only and should not be interpreted as limiting the invention.

[0088]

[0089] Examples

[0090] The specifications of each component used in the examples and comparative examples below are as follows.

[0091] (A) High melt strength polypropylene resin

[0092] High melt tensile strength polypropylene resin (Manufacturer: Lotte Chemical, Product Name: HMS-130) was used.

[0093] (B) Block polypropylene resin

[0094] Block polypropylene resin (Manufacturer: Lotte Chemical, Product Name: B-310) was used.

[0095] (C) Zinc oxide

[0096] Zinc oxide (Manufacturer: Hanil Chemical, Product Name: KS-1) was used.

[0097] (D) Zinc organic compounds

[0098] (D1) Zinc acetylacetonate (Zn(Acac)2, Manufacturer: Sigma-Aldrich) was used.

[0099] (D2) Zinc acetate (Zn(Ac)2, Manufacturer: Deoksan Science) was used.

[0100]

[0101] Examples 1 to 8 and Comparative Examples 1 to 6

[0102] After adding each of the above components in amounts as listed in Tables 1, 2, and 3 below, a polypropylene resin composition for foam injection molding (in pellet form) was prepared by extruding at approximately 220°C. A single-screw extruder with L / D=40 and a diameter of 39.8 mm (screw rotation speed: 250 rpm, feed speed: 40 kg / hr) was used for extrusion.

[0103] Next, using a Super-Foam foam injection molding machine (manufacturer: Woojin Plaim, 360 tons), the above-mentioned polypropylene resin composition for foam injection was placed into a square mold measuring 24.6 cm × 24.6 cm × 2 cm, and a core bag was applied while performing physical foam injection to produce a foamed molded body. Here, nitrogen (N2) was used as the foaming gas for the physical foam injection, and the process was performed under conditions of a foaming gas pressure of 90 bar, a cylinder temperature of 220°C, and a mold temperature of 80°C, and after applying a holding pressure of 300 bar for about 2 to about 10 seconds, a core bag of 20 mm was performed.

[0104] The physical properties of the manufactured foamed molded articles were evaluated by the following method, and the results are shown in Tables 1 and 2 below.

[0105]

[0106] Methods for measuring physical properties

[0107] (1) Thermal conductivity (unit: W / m·K): According to KS M 3809, a foam injection molded specimen measuring 24.6 cm × 24.6 cm × 2 cm was placed in a thermal conductivity analysis device (manufacturer: NETZSCH, device name: HFM 436) and the thermal conductivity was measured.

[0108] (2) Antimicrobial activity value: According to the JIS Z 2801 antimicrobial evaluation method, Staphylococcus aureus and Escherichia coli were inoculated into injection-molded specimens measuring 5 cm × 5 cm, cultured for 24 hours at 35°C and RH 90%, and then the antimicrobial activity value was measured.

[0109] (3) Falling dart impact total energy (unit: J): According to ASTM D1709, the falling dart impact total energy of a foam injection molded specimen measuring 10 cm × 10 cm × 2 cm was measured under conditions of 5 kg, 1 m.

[0110] (4) Specific gravity: The specific gravity of the foam injection molded specimen was calculated according to the following Equation 1.

[0111] [Equation 1]

[0112] Specific gravity = Weight of specimen / Weight of specimen submerged in water

[0113] In the above Equation 1, the specimen weight is the weight of a foam injection molded specimen with dimensions of 3 cm × 3 cm × 2 cm, and the submerged specimen weight is the weight measured when the foam injection molded specimen is completely submerged in water.

[0114]

[0115] Example 1 234(A) (Weight%) 20 40 60 40(B) (Weight%) 80 60 40 60(C) (Parts by weight) 3.8 3.8 3.8 1.9(D1) (Parts by weight) 0.3 0.3 0.3 0.3(D2) (Parts by weight) --- Thermal conductivity 0.05 40.05 40.05 10.05 2 Antibacterial activity Staphylococcus aureus 3.6 3.5 3.3 3.4 Escherichia coli 4.0 4.0 3.9 4.0 Total impact energy 7.7 6.0 4.1 6.3 Specific gravity 0.2 0.2 0.1 9 0.19

[0116] * Parts by weight: Parts by weight relative to 100 parts by weight of base resin (A+B)

[0117]

[0118] Example 5678(A) (Weight%) 40 40 40 40(B) (Weight%) 60 60 60 60 (C) (Parts by weight) 2.9 3.8 3.8 3.8 (D1) (Parts by weight) 0.3 0.6 1.2 - (D2) (Parts by weight) --- 0.3 Thermal conductivity 0.05 40.05 10.05 10.05 2 Antimicrobial activity Staphylococcus aureus 3.5 3.3 3.7 3.4 Escherichia coli 4.1 4.0 3.9 4.2 Total surface impact energy 6.1 6.2 6.0 6.1 Specific gravity 0.2 0.2 0.2 0.2 0.2 0

[0119] * Parts by weight: Parts by weight relative to 100 parts by weight of base resin (A+B)

[0120]

[0121] Comparative Example 123456(A) (Weight%) 107040404040(B) (Weight%) 903060606060(C) (Parts by weight) 3.83.80.55.73.83.8(D1) (Parts by weight) 0.30.30.30.30.012(D2) (Parts by weight)------Thermal conductivity 0.0810.0500.0550.0720.0710.054 Antibacterial activity Staphylococcus aureus 3.43.31.23.93.63.5 Escherichia coli 3.94.11.44.83.93.9 Total impact energy 15.52.76.36.06.52.8 Specific gravity 0.390.200.200.320.310.20

[0122] * Parts by weight: Parts by weight relative to 100 parts by weight of base resin (A+B)

[0123]

[0124] From the above results, it can be seen that the polypropylene resin composition for foam injection molding of the present invention has excellent thermal insulation (thermal conductivity), antibacterial properties (antibacterial activity), surface durability (total surface impact energy), and a balance of these physical properties, and has excellent lightness (specific gravity).

[0125] On the other hand, in Comparative Example 1, in which high melt strength polypropylene resin is used in an amount less than the content range of the present invention and block polypropylene resin is used in an amount greater than the content range of the present invention, it can be seen that thermal insulation properties, etc. are reduced, and in Comparative Example 2, in which high melt strength polypropylene resin is used in an amount greater than the content range of the present invention and block polypropylene resin is used in an amount less than the content range of the present invention, it can be seen that surface durability properties, etc. are reduced.

[0126] In addition, in Comparative Example 3, in which zinc oxide was used at a content range below that of the present invention, it can be seen that antibacterial properties, etc. were reduced; in Comparative Example 4, in which zinc oxide was used at a content range above that of the present invention, it can be seen that thermal insulation properties, etc. were reduced; in Comparative Example 5, in which zinc organic compound was used at a content range below that of the present invention, it can be seen that thermal insulation properties, etc. were reduced; and in Comparative Example 6, in which zinc organic compound was used at a content range above that of the present invention, it can be seen that surface durability, etc. was reduced.

[0127]

[0128] The present invention has been described above with reference to embodiments. Those skilled in the art will understand that the present invention may be embodied in modified forms without departing from the essential characteristics of the invention. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the invention is defined by the claims, not by the foregoing description, and all variations within the scope of equivalents should be interpreted as being included in the invention.

Claims

1. 100 parts by weight of a base resin comprising 15 to 65 weight% of high melt tension polypropylene resin and 35 to 85 weight% of block polypropylene resin; 1.5 to 4.5 parts by weight of zinc oxide; and A polypropylene resin composition for foam injection molding characterized by comprising 0.1 to 1.5 parts by weight of a zinc organic compound.

2. A polypropylene resin composition for foam injection molding according to claim 1, characterized in that the high melt tension polypropylene resin has a melt tension of 25 to 45 cN as measured by a réthense device.

3. A polypropylene resin composition for foam injection molding according to claim 1, characterized in that the high melt strength polypropylene resin has a melt-flow index of 0.1 to 10 g / 10 min measured under conditions of 230°C and a 2.16 kg load in accordance with ASTM D1238.

4. A polypropylene resin composition for foam injection molding according to claim 1, characterized in that the block polypropylene resin is a block polypropylene resin composed of one or more of a homopolypropylene block, an ethylene-propylene copolymer block, and a homopolyethylene block.

5. A polypropylene resin composition for foam injection molding according to claim 1, characterized in that the block polypropylene resin has a melt-flow index of 0.1 to 5 g / 10 min measured at 230°C and a 2.16 kg load condition in accordance with ASTM D1238.

6. A polypropylene resin composition for foam injection molding according to claim 1, characterized in that the zinc organic compound comprises one or more of zinc acetylacetonate and zinc acetate.

7. A polypropylene resin composition for foam injection molding according to claim 1, characterized in that the weight ratio of the zinc oxide and the zinc organic compound is 1:0.04 to 1:0.

5.

8. The polypropylene resin composition for foam injection according to claim 1, characterized in that the thermal conductivity of a foam injection specimen measuring 24.6 cm × 24.6 cm × 2 cm, measured in accordance with KS M 3809, is 0.04 to 0.06 W / m·K.

9. The polypropylene resin composition for foam injection molding according to claim 1, characterized in that the antibacterial activity value measured after inoculating a 5 cm × 5 cm specimen with Staphylococcus aureus and Escherichia coli according to the JIS Z 2801 antibacterial evaluation method and culturing for 24 hours under conditions of 35°C and RH 90% is 2 to 7, respectively.

10. The polypropylene resin composition for foam injection molding according to claim 1, characterized in that the total surface impact energy of a foam injection molding specimen measuring 10 cm × 10 cm × 2 cm is 3 to 10 J, measured under conditions of 5 kg and 1 m in accordance with ASTM D1709.

11. The polypropylene resin composition for foam injection molding according to claim 1, characterized in that the specific gravity calculated according to Formula 1 below is 0.05 to 0.5: [Equation 1] Specific gravity = Weight of specimen / Weight of specimen submerged in water In the above Equation 1, the specimen weight is the weight of a foam injection molded specimen with dimensions of 3 cm × 3 cm × 2 cm, and the submerged specimen weight is the weight measured when the foam injection molded specimen is completely submerged in water.

12. A polypropylene resin composition for foam injection according to any one of claims 1 to 11 is formed by physical foam injection using a core-back method, and A foamed molded body characterized by comprising a first non-foamed surface layer, an internal foamed layer, and a second non-foamed surface layer.

13. A foamed molded article according to claim 12, wherein the first surface layer and the second surface layer each have a thickness of 0.3 to 0.7 mm.

14. A foamed molded article according to claim 12, characterized in that the internal foam layer has a thickness of 9 to 40 mm.

15. A method for manufacturing a foamed molded article characterized by comprising the step of: placing a polypropylene resin composition for foam injection according to any one of claims 1 to 11 into a mold of a physical foam injection machine; and injecting nitrogen as a foaming gas into the mold, and, under conditions of a foaming gas pressure of 80 to 240 bar, a cylinder temperature of 200 to 230°C, and a mold temperature of 60 to 90°C, applying a holding pressure of 300 bar for 2 to 10 seconds, and then advancing the core bag by 9 to 40 mm.

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