Plate for ship hull having recycled hdpe and uhmwpe composite and method for preparing the same

Abstract

The plate material for a ship hull comprising the recycled high-density polyethylene resin and the ultra-high molecular weight polyethylene composite of the present invention comprises high-density polyethylene; and ultra-high molecular weight polyethylene; and comprises a composite formed by mechanical blending of the high-density polyethylene and the ultra-high molecular weight polyethylene, wherein the weight ratio of the ultra-high molecular weight polyethylene to the recycled high-density polyethylene is 10 to 30: 90 to 70.

Description

Technology Field

[0001] The present invention relates to a plate for a ship hull comprising recycled high-density polyethylene resin and an ultra-high molecular weight polyethylene composite, and a method for manufacturing the same. More specifically, the present invention relates to an environmentally friendly plate for a ship hull comprising recycled high-density polyethylene resin and an ultra-high molecular weight polyethylene composite, and a method for manufacturing the same. Background Technology

[0003] Conventionally, most small vessels have been manufactured primarily from FRP (Fiber Reinforced Plastic) material. However, FRP materials have the disadvantage of being difficult to recycle and incurring disposal costs of over 1 million won per ton. Consequently, used FRP vessels are often left in nature instead of being recycled or disposed of, causing environmental pollution. Furthermore, FRP vessels generate glass dust during the manufacturing process, and the paint used on the ships significantly pollutes shipyard workers and the surrounding environment. In particular, microplastics and glass fibers are released from older FRP vessels, entering the food chain and disrupting the ecosystem.

[0004] In order to solve these problems, research on alternative materials to FRP is actively underway, and although attempts were made to manufacture ships using aluminum, they failed to gain traction in the market due to high costs and difficulties in repair. To date, there is no suitable alternative, and the proportion of FRP ships among Korean fishing vessels has reached approximately 97%.

[0005] Recently, high-density polyethylene (HDPE) has been attracting attention as a material for eco-friendly ship hulls. It has already been commercialized overseas and is being manufactured and operated as leisure boats, while demonstration projects to verify the material are currently underway in Korea.

[0006] However, when manufacturing hulls using sheets made of virgin HDPE, there is a problem in that not only does the environmental burden associated with HDPE production increase, but raw material costs also rise significantly.

[0007] Therefore, there is an urgent need to develop eco-friendly ship hull plates that can be used more efficiently by reducing environmental burden and manufacturing costs. The problem to be solved

[0009] The objective of the present invention is to provide a plate material for a ship hull using recycled high-density polyethylene resin and ultra-high molecular weight polyethylene.

[0010] The ship hull plate can reduce environmental pollution and increase resource recycling by utilizing recycled high-density polyethylene resin, and by securing lightweightness, flame resistance, impact resistance, and rigidity using recycled high-density polyethylene resin, it can provide a plate that can be used as the hull of various ships by replacing conventional pure high-density polyethylene resin.

[0011] The invention provides an eco-friendly ship hull plate that can prevent environmental pollution by limiting harmful components of the above-mentioned recycled high-density polyethylene resin.

[0012] Another objective of the present invention is to provide a method for manufacturing the above-mentioned eco-friendly ship hull.

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

[0015] 1. One aspect of the present invention relates to a plate for a ship hull comprising a recycled high-density polyethylene resin and an ultra-high molecular weight polyethylene composite. The plate for the ship comprises a composite comprising high-density polyethylene and ultra-high molecular weight polyethylene, and

[0016] The above high-density polyethylene includes recycled high-density polyethylene, and

[0017] The weight ratio of the above ultra-high molecular weight polyethylene and high-density polyethylene is 10 to 30: 90 to 70.

[0018] 2. In the above 1 embodiment, the high-density polyethylene may be recycled high-density polyethylene alone.

[0019] 3. In the above 1 or 2 embodiments, the high-density polyethylene may be a mixture of recycled high-density polyethylene and virgin high-density polyethylene.

[0020] 4. In the above 1 to 4 embodiments, the recycled high-density polyethylene may be derived from one or more of an engine oil container, a detergent container, and a milk container.

[0021] 5. In the above embodiments 1 to 4, the recycled high-density polyethylene has a melt index (MFR) of 0.26 g / 10 min or less as measured according to ISO 1133, and a density of 0.949 g / cm³ as measured according to ASTM D792. 3 It could be more than that.

[0022] 6. In the above 1 to 5 embodiments, the recycled high-density polyethylene may have a yield stress of 25.2 MPa or more as measured according to ASTM D638, a breaking strength of 16.3 MPa or more as measured according to ASTM D638, a flexural strength of 24.6 MPa or more as measured according to ASTM D790, and a flexural modulus of 953.2 MPa or more as measured according to ASTM D790.

[0023] 7. In the above 1 to 6 embodiments, the recycled high-density polyethylene may have a notched Izod impact strength (0°C) of 350 J / m or more and a notched Izod impact strength (-10°C) of 245 J / m or more as measured according to ASTM D256.

[0024] 8. In the above 1 to 6 embodiments, the recycled high-density polyethylene may contain 230 to 250 ppm of oxide of a phosphite-based antioxidant as a result of analysis by high-performance liquid chromatography (HPLC).

[0025] 9. In the above 1 to 8 embodiments, the weight ratio of the phosphite-based antioxidant to the oxide of the phosphite-based antioxidant in the recycled high-density polyethylene may be 2.5 to 3:1 as a result of analysis by high-performance liquid chromatography (HPLC).

[0026] 10. In the above 9 embodiments, the phosphite-based antioxidant may be further added in an amount equal to the weight ratio of the oxide of the phosphite-based antioxidant.

[0027] 11. In the above 1 to 10 embodiments, the eco-friendly ship hull plate may contain polybrominated biphenyl (PBB) and polybrominated diphenyl ether (PBDE) compounds in an amount of 0.1 wt% or less.

[0028] 12. In the above 1 to 11 embodiments, with respect to 100 parts by weight of the composite,

[0029] 0.01 to 5 parts by weight of light stabilizer;

[0030] 0.01 to 4 parts by weight of carbon material;

[0031] It may further include 0.01 to 2 parts by weight of an antioxidant.

[0032] 13. Another aspect of the present invention relates to a method for manufacturing a plate for a ship hull.

[0033] The above method for manufacturing a plate for a ship hull comprises the step of manufacturing a pellet containing high-density polyethylene and ultra-high molecular weight polyethylene;

[0034] A step of forming the above pellets into a sheet shape; and

[0035] The method includes the step of cutting the above sheet into the shape of a ship hull part; and

[0036] The above high-density polyethylene includes recycled high-density polyethylene, and

[0037] The weight ratio of the above ultra-high molecular weight polyethylene and recycled high-density polyethylene is 10 to 30: 90 to 70.

[0038] 14. In the above 13 embodiments, the step of manufacturing the pellets can be performed by extrusion molding at a temperature of 170 to 240°C using a twin-screw extruder.

[0039] 15. In the above 13 or 14 embodiments, the pellet may not contain polybrominated biphenyl (PBBs) and polybrominated diphenyl ether (PBDEs) compounds.

[0040] 16. In the above 13 to 15 embodiments, the weight ratio of the phosphite-based antioxidant to the oxide of the phosphite-based antioxidant may be 2.5 to 3:1 as a result of analysis by chromatography (HPLC) of the pellet.

[0041] 17. In the above 16 embodiments, the phosphite-based antioxidant may be further added in an amount equal to the weight ratio of the phosphite-based antioxidant oxide. Effects of the invention

[0043] The present invention provides a ship hull plate utilizing recycled high-density polypropylene, which is highly environmentally friendly. Furthermore, the ship hull plate ensures lightweightness, flame resistance, impact resistance, and rigidity, making it suitable for use as the hull of various types of ships.

[0044] By utilizing recycled plastics as a resource, the resource recycling rate can be increased, carbon emissions can be reduced, and raw material costs can be significantly lowered.

[0045] Due to its high rigidity, it is possible to secure the mechanical strength and durability of the ship structure, improve fuel efficiency compared to existing FRP ships, and reduce ship maintenance costs by exhibiting weather resistance.

[0046] A method for manufacturing a ship hull plate according to another aspect of the present invention utilizes recycled high-density polyethylene to reduce environmental burden and lower manufacturing costs, thereby significantly improving the efficiency of manufacturing ship hull plates. Brief explanation of the drawing

[0048] FIG. 1 is a cross-sectional view of a plate for a ship hull having a single-layer structure according to one embodiment of the present invention. FIG. 2 is a cross-sectional view of a plate for a ship hull having a multilayer structure according to one embodiment of the present invention. FIG. 3 is a nesting drawing for manufacturing a plate for a ship hull according to one embodiment of the present invention. Figure 4 is a graph showing the results of high-performance liquid chromatography (HPLC) analysis of recycled high-density polyethylene included in a ship hull plate according to one embodiment of the present invention. FIG. 5 is a table showing the results of an analysis of the restriction of hazardous substances in recycled high-density polyethylene included in a ship hull plate according to one embodiment of the present invention. Specific details for implementing the invention

[0049] The present invention will be described in detail below.

[0050] In this specification, "a to b" indicating a numerical range is defined as "≥a and ≤b".

[0051] In this specification, unless otherwise noted, molecular weight is the weight-average molecular weight (Mw) measured by gel permeation chromatography (GPC) at 160°C under TCB (1,2,4-trichlorobenzene) conditions.

[0052] A plate material for a ship hull comprising a recycled high-density polyethylene resin and an ultra-high molecular weight polyethylene composite according to the present invention comprises high-density polyethylene and a composite comprising ultra-high molecular weight polyethylene.

[0054] High-density polyethylene

[0055] The above high-density polyethylene refers to a material that is a polymer or copolymer of ethylene, which may include an ethylene homopolymer or a copolymer with an α-olefin (e.g., 1-butene, 1-hexene, 1-octene), has a density in the range of 0.940-0.970 g / cm³ as measured at 23°C according to ISO 1183-1, and is in a non-crosslinked thermoplastic state.

[0056] In one embodiment, the high-density polyethylene may include recycled high-density polyethylene.

[0057] In one embodiment, the high-density polyethylene may comprise recycled high-density polyethylene alone.

[0058] The above-mentioned recycled high-density polyethylene (recycled HDPE; hereinafter 'rHDPE') refers to high-density polyethylene recovered and reprocessed, having a weight-average molecular weight lower than that of ultra-high molecular weight polyethylene.

[0059] The above rHDPE may originate from household waste such as plastic containers and cases discarded after use, and industrial waste such as plastic pipes and pellets generated from industrial processes, and may be in the form of a powder obtained by selecting high-density polyethylene from plastic waste, washing it, and then crushing and grinding it.

[0060] For example, it may be derived from one or more of engine oil containers, detergent containers and milk containers, and preferably, rHDPE may be derived from discarded engine oil containers.

[0061] The above-mentioned engine oil container is a general-purpose and non-food grade recyclable that can be recovered through the reprocessing process described above, and the engine oil container exhibits high molecular weight and high Environmental Stress Crack Resistance (ESCR). In particular, it is highly suitable for securing physical properties suitable for marine environments, as it is designed to be excellent against chemical cracking and creep when exposed to hydrocarbons such as lubricating oil for a long period.

[0062] The above-mentioned engine oil container is predominantly black or dark in color, and it is easy to obtain one that already contains carbon materials such as carbon black; this is desirable because it not only reduces the content of carbon black added to ensure UV durability during the manufacture of hull plates but also ensures weldability.

[0063] Since the above-mentioned engine oil container already contains light stabilizers and antioxidants, it is easy to secure excellent chemical resistance, durability, and weather resistance compared to other uses or general plastic waste, so the effects of the present invention can be realized when utilized as recycled high-density polyethylene.

[0064] The above engine oil container may have a melt index (MFR, 190℃ / 2.16 kg) according to ISO 1133 of 0.03 to 10.0 g / 10 min, may contain 1.5 to 3.0 weight% of carbon black, and may exhibit ESCR to implement the present invention.

[0065] The rHDPE derived from the above-mentioned engine oil container has a melt index (MFR) of 0.26 g / 10 min or less as measured according to ISO 1133, for example, 0.2 to 0.26 g / 10 min, and a density of 0.949 g / cm³ as measured according to ASTM D792. 3 Above, for example, 0.949 g / cm³ 3 Up to 0.96 g / cm³ 3 It could be.

[0066] The above rHDPE exhibits a melt index and density within the above range, thereby ensuring processability, weldability, and rigidity of the above eco-friendly ship hull plate, enabling resistance to impact and chemical resistance, and establishing a standard for thickness design to manufacture the plate within the target thickness.

[0067] The above rHDPE may have a yield stress of 25.2 MPa or more, for example, 25.2 to 30 MPa, measured according to ASTM D638, a breaking strength of 16.3 MPa or more, for example, 16.3 to 20 MPa, measured according to ASTM D638, a flexural strength of 24.6 MPa or more, for example, 24.6 to 30 MPa, measured according to ASTM D790, and a flexural modulus of 953.2 MPa or more, for example, 953.2 to 960 MPa, measured according to ASTM D790.

[0068] Within the above range, the yield stress of the rHDPE can establish standard values ​​for the allowable stress and plate thickness calculation when designing plates, the plate thickness can be designed within the target range, and plates for ship hulls can be manufactured according to the standard values ​​presented by the Korean Register of Shipping.

[0069] Within the range of the above-mentioned breaking strength, the ductility and safety margin of the plate can be secured, and within the range of the above-mentioned bending strength and bending modulus, the plate can resist bending or impact caused by local forces and have resistance to buckling or deformation.

[0070] The above rHDPE may have a notched Izod impact strength (0°C) of 350 J / m or more, for example, 350 to 400 J / m, measured according to ASTM D256, and a notched Izod impact strength (-10°C) of 245 J / m or more, for example, 245 to 260 J / m.

[0071] Within the above range, the risk of brittle fracture from impact and drift impact at low temperatures can be reduced, and warping due to machinability and shrinkage can be prevented.

[0072] If the above rHDPE exhibits low-temperature impact strength within the above range, it can satisfy the standard values ​​presented by the Korean Register of Shipping.

[0073] A plate material for a ship hull according to one embodiment of the present invention is derived from the rHDPE used in discarded engine containers, and can secure the target impact resistance and rigidity when satisfying the physical property conditions, and can replace virgin HDPE (virgin HPDE) used as a conventional plate material for ship hulls.

[0074] Meanwhile, the rHDPE may contain 230 to 250 ppm of oxides of phosphite-based antioxidants as a result of analysis by high-performance liquid chromatography (HPLC).

[0075] Virgin HDPE may include primary antioxidants and secondary antioxidants. Virgin HDPE refers to pure HDPE that has not been recycled. The primary antioxidant performs the function of a radical scavenger by reacting with radicals generated within the resin to stabilize the synthetic resin, and may include, typically, phenolic (I-1010, I-1076) and amine-based antioxidants.

[0076] The above secondary antioxidant is a peroxide decomposer that decomposes peroxides generated by radicals into stable molecules, and may include, typically, phosphite and thioester oxidizers.

[0077] The rHDPE derived from the above engine oil container contains a phosphite-based antioxidant (I-168) as a secondary antioxidant, and the phosphite-based antioxidant may be detected as an oxidized state in an inactive state after peroxide decomposition following heat reprocessing when detected by HPLC.

[0078] The above phosphite-based antioxidant acts as a peroxide decomposer and can be converted into an oxide of the phosphite-based antioxidant in an inactive state when treating peroxides already formed in HDPE, and the rHDPE may contain 230 to 250 ppm of the oxide of the phosphite-based antioxidant.

[0079] The oxide of the above-mentioned phosphite-based antioxidant is included within the above range, and the rHDPE has a history of stress due to heat and oxygen, and there is a need to supplement the peroxide decomposition ability.

[0080] The above rHDPE may have a weight ratio of a phosphite-based antioxidant to an oxide of the phosphite-based antioxidant of 2.5 to 3:1 as a result of analysis by high-performance liquid chromatography (HPLC), and within the above weight ratio range, the phosphite-based antioxidant is included so that radical scavenging ability remains, and the resin can be stabilized by scavenging radicals during the production of hull plates.

[0081] In one embodiment, the phosphite-based antioxidant may be further added in an amount equal to the weight ratio of the oxide of the phosphite-based antioxidant. When manufacturing the eco-friendly ship hull plate, the oxidation induction time (OIT) may decrease in high-temperature processes such as twin-screw compressors, which may cause problems with the dispersion and stabilization of the resin; however, the process can be stabilized during the pelletizing and sheet-forming process by compensating for the oxidized and deactivated phosphite-based antioxidant oxide by adding the phosphite-based antioxidant in an amount equal to the weight ratio of the phosphite-based antioxidant oxide.

[0082] Since the above rHDPE is sensitive to additional oxidation triggers, metal residues caused by contamination during catalyst or recycling, high temperature retention, acidic impurities, etc., promote additional consumption and hydrolysis of the above phosphite-based antioxidant (I-168), the above rHDPE may have metal components such as Ti, Mg, Al, and Ca removed according to ash residue elemental analysis.

[0083] The above rHDPE may contain polybrominated biphenyls (PBBs) and polybrominated diphenyl ethers (PBDEs) compounds in an amount of 0.1 wt% or less.

[0084] The above polybrominated biphenyls (PBBs) may be one or more of Bromobiphenyl, Dibromobiphenyl, Tribromobiphenyl, Tetrabromobiphenyl, Pentabromobiphenyl, Hexabromobiphenyl, Heptabromobiphenyl, Octabromobiphenyl, Nonabromobiphenyl, and Decabromobiphenyl, and the above polybrominated diphenyl ethers (PBDEs) may be one or more of Bromodiphenyl ether, Dibromodiphenyl ether, Tribromodiphenyl ether, Tetrabromodiphenyl ether, Pentabromodiphenyl ether, Hexabromodiphenyl ether, Heptabromodiphenyl ether, Octabromodiphenyl ether, Nonabromodiphenyl ether, and Decabromodiphenyl ether.

[0085] The above-mentioned polybrominated biphenyls (PBBs) and polybrominated diphenyl ethers (PBDEs) compounds are used as flame retardants and are mixed into recycled HDPE, but the eco-friendly ship hull plate containing the above-mentioned rHDPE must satisfy the Restriction of Hazardous Substances (RoHS) directive, and the above-mentioned rHDPE can satisfy RoHS by including 0.1 wt% of the above-mentioned flame retardants, for example, 0 to 0.1 wt%.

[0086] The above rHDPE may contain 20 wt% or less of virgin HDPE. For example, it may contain 5 to 20 wt%. It is also possible to further improve weather resistance by including virgin HDPE within the above range in the above rHDPE.

[0087] The above rHDPE may have a weight-average molecular weight (Mw) of 120,000 g / mol or more and less than 600,000 g / mol, preferably 150,000 to 450,000 g / mol, and a molecular weight distribution (MWD) of 6 to 20 and 8 to 15. The weight-average molecular weight of the above rHDPE may be reduced compared to virgin HDPE during the reprocessing process for collection and recycling, for example, due to chain breakage caused by thermal oxidative decomposition by heat, oxygen, mixed transition metals, and acidic residues, but it may exhibit the target stiffness and impact resistance when used as a plate material for ship hulls.

[0088] In addition, the density of the above high-density polyethylene is 0.94 to 0.97 g / cm³ 3 It may be possible. Within the above range, the eco-friendly ship hull plate can secure the target lightweight properties and may have excellent rigidity, impact resistance, etc.

[0090] ultra-high molecular weight polyethylene

[0091] The above ultra-high molecular weight polyethylene (UHMWPE) may have a weight-average molecular weight of 1,000,000 g / mol or more, for example, 1,000,000 to 7,000,000 g / mol, in one embodiment 1,500,000 to 6,500,000 g / mol, preferably 2,500,000 to 6,000,000 g / mol. Within this range, superior tensile strength can be imparted to the above-mentioned eco-friendly ship hull plate.

[0092] The above ultra-high molecular weight polyethylene (UHMWPE) may have a density of 0.920 to 0.939 g / cm³.

[0093] Within the above range, the plate material for eco-friendly ship hulls can exhibit the desired rigidity and impact resistance.

[0095] complex

[0096] The above composite includes high-density polyethylene and ultra-high molecular weight polyethylene.

[0097] The above high-density polyethylene (HDPE) and ultra-high molecular weight polyethylene (UHMWPE) can form a composite by mechanical blending, for example, by compounding through a twin-screw extruder in which the ultra-high molecular weight polyethylene is dispersed in phase within the recycled high-density polyethylene or may be a compound.

[0098] The weight ratio of the ultra-high molecular weight polyethylene to the high-density polyethylene is characterized by being 10 to 30: 90 to 70. In a specific example, the ultra-high molecular weight polyethylene may be 10 to 30 weight%, preferably 7 to 25 weight%, and 10 to 20 weight% in a specific example, out of 100 weight% of the total composite. By including ultra-high molecular weight polyethylene within the above range, the target melt index is achieved, which facilitates dispersion during compounding, thereby reducing the load on the equipment and preventing warping of the sheet metal during the manufacturing process. Additionally, a target yield stress of 25 MPa or higher can be achieved.

[0099] The above composite comprises the recycled high-density polyethylene alone, or a mixture of pure virgin high-density polyethylene that is not recycled.

[0101] light stabilizer

[0102] A light stabilizer according to one embodiment of the present invention may include one or more of an ultraviolet absorber, a hindered amine-based light stabilizer, and an ultraviolet stabilizer.

[0103] In a specific example, the ultraviolet absorber may include a benzophenone-based ultraviolet absorber, a benzotriazole-based ultraviolet absorber, a salicylic acid-based ultraviolet absorber, a cyanoacrylate-based ultraviolet absorber, a combination thereof, etc.

[0104] Examples of the above-mentioned benzophenone-based ultraviolet absorbers include, but are not limited to, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2,2'-dihydroxy-4-dimethoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, bis(2-methoxy-4-hydroxy-5-benzoylphenyl)methane, and combinations thereof.

[0105] The above-mentioned benzotriazole-based ultraviolet absorbers include, for example, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-5'-tert-butylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)benzotriazole, 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)5-chlorobenzotriazole, 2-(2'-hydroxy-3',5'-di-tert-amylphenyl)benzotriazole, 2-(2'-hydroxy-4'-octoxyphenyl)benzotriazole, Examples include 2-[2'-hydroxy-3'-(3",4",5",6",-tetrahydrophthalimidemethyl)-5'-methylphenyl]benzotriazole, 2,2'methylenebis[4-(1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazole-2-yl)phenol], [2(2'-hydroxy-5'-methacryloxyphenyl)-2H-benzotriazole, combinations thereof, etc., but are not limited thereto.

[0106] Examples of the above salicylic acid-based ultraviolet absorbers include, for instance, phenyl salicylate, p-tert-butylphenyl salicylate, p-octylphenyl salicylate, and combinations thereof, but are not limited thereto.

[0107] Examples of the above-mentioned cyanoacrylate-based ultraviolet absorbers include, for instance, 2-ethylhexyl-2-cyano-3,3'-diphenylacrylate, ethyl-2-cyano-3,3'-diphenylacrylate, and combinations thereof, but are not limited thereto.

[0108] Examples of the hindered amine-based light stabilizers mentioned above include, for instance, [bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate], bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate, methyl 1,2,2,6,6-pentamethyl-4-piperidylsebacate, and combinations thereof, but are not limited thereto.

[0109] Examples of the above-mentioned UV stabilizers include, but are not limited to, nickel bis(octylphenyl)sulfide, [2,2'-thiobis(4-tert-octylphenolate)]-n-butylamine nickel, nickel complex-3,5-di-tert-butyl-4-hydroxybenzyl-phosphate monoethylate, nickel-dibutyldithiocarbamate, benzoate-type quencher, nickel-dibutyldithiocarbamate, and combinations thereof.

[0110] In a specific example, the light stabilizer may be included in an amount of 0.01 to 5 parts by weight, for example, 0.05 to 1 part by weight, per 100 parts by weight of the composite. Within this range, the weather resistance (maintaining yellow index, etc.) and impact resistance of the eco-friendly ship hull may be excellent.

[0112] carbon material

[0113] In the present invention, the carbon material is dispersed in the composite to form a dispersed phase.

[0114] In a specific example, the carbon material may include one or more of carbon black, carbon fiber, carbon nanotube, graphite, and graphene.

[0115] The carbon material may have an average particle size (D50) of 5 to 50 nm, for example, 10 to 45 nm, as measured by a transmission electron microscope (TEM). Within this range, the surface area increases and the UV absorption rate increases, so the weather resistance (maintenance of long-term properties) of the eco-friendly ship hull can be excellent.

[0116] In a specific example, the carbon material may be included in an amount of 0.01 to 4 parts by weight, for example, 1 to 3 parts by weight, per 100 parts by weight of the composite. Within this range, the flexural modulus and flexural strength of the eco-friendly ship hull plate can be improved, and the thickness of the plate can be reduced while maintaining the same stiffness target. In addition, the color change of the rHDPE can be suppressed, and weather resistance can be ensured by exhibiting a uniform black color, and the initiation of surface cracks can be prevented through inherent scattering and absorption effects.

[0118] antioxidants

[0119] An antioxidant according to one embodiment of the present invention is applied to high-density polyethylene together with a carbon material and a light stabilizer, and can improve the eco-friendliness, durability, impact resistance, and balance of the physical properties thereof of an eco-friendly ship hull.

[0120] In a specific example, the antioxidant may include one or more of hindered phenol compounds, aromatic amine compounds, phosphite compounds, phosphonite compounds, organic sulfur-containing compounds, and dithiophosphonate compounds.

[0121] In a specific example, the antioxidant may be a commercially available product, such as Irganox 1010, Irgafos 168, or a mixture thereof, but is not limited thereto.

[0122] In a specific example, the antioxidant may be included in an amount of 0.01 to 5 parts by weight, for example, 0.05 to 1 part by weight, per 100 parts by weight of the high-density polyethylene. Within this range, oxidation heat reactions, etc., can be suppressed during the manufacture of pellets and sheets for producing eco-friendly ship hull plates, and processing stability can be excellent.

[0124] additives

[0125] An eco-friendly ship hull plate according to one embodiment of the present invention may further include additives included in a conventional thermoplastic resin composition. Examples of said additives include, but are not limited to, flame retardants, anti-scratching agents, antibacterial agents, heat stabilizers, lubricants, release agents, nucleating agents, antistatic agents, dispersants, processing aids, compatibilizers, pigments, and mixtures thereof.

[0126] In a specific example, the pigment may be used as a pigment alone or in the form of a pigment masterbatch (MB (Master Batch)).

[0127] In a specific example, the pigment may include monoazo pigments, diazo pigments, anthraquinone pigments, benzimidazole pigments, quinacridone pigments, quinophthalone pigments, diketopyrrolopyrrole pigments, dioxazine pigments, indantron pigments, isoindolin pigments, isoandolinone pigments, metal complex pigments, perinone pigments, perylene pigments, phthalocyanine pigments, non-neutral pigments, mixtures thereof, etc.

[0128] In a specific example, when the above pigment is applied, various colors can be applied to the ship without the environmental pollution problems associated with the use of paint in conventional ship manufacturing.

[0129] In a specific example, when using the above additive, the content may be 0.001 to 40 parts by weight, for example 0.01 to 10 parts by weight, with respect to 100 parts by weight of the above complex, but is not limited thereto.

[0131] Sheet metal

[0132] FIG. 1 is a cross-sectional view of a plate for a ship hull having a single-layer structure according to one embodiment of the present invention, and FIG. 2 is a cross-sectional view of a plate for a ship hull having a multi-layer structure according to one embodiment of the present invention.

[0133] Referring to Figures 1 and 2, the above-described eco-friendly ship hull plate is formed by mixing the rHDPE and ultra-high molecular weight polyethylene, pelletizing them, remelting them, and then compression molding them into a sheet shape using a twin-screw extruder, and each component can be formed into a sheet shape.

[0134] The above-mentioned eco-friendly ship hull plate may have a multilayer structure, for example, by using a multilayer twin-screw extruder to form a first surface layer (110), a core (100), and a second surface layer (120), and the first surface layer (110) and the second surface layer (120) may contain 30 wt% of ultra-high molecular weight polyethylene and additionally add carbon material to further increase the impact resistance and weather resistance of the surface layer, and the core (100) may contain 10 wt% of ultra-high molecular weight polyethylene to exhibit weldability and rigidity, thereby reducing manufacturing costs.

[0135] The above-mentioned eco-friendly ship hull plates can be utilized in ships, floating structures, marine equipment, etc.

[0137] Method for manufacturing eco-friendly ship hull plates

[0138] An eco-friendly ship hull plate according to one embodiment of the present invention can be manufactured by a manufacturing method comprising the steps of: manufacturing a pellet comprising recycled high-density polyethylene and ultra-high molecular weight polyethylene; forming the pellet into a sheet; and cutting the sheet into a ship hull part.

[0139] The step of manufacturing the above pellets can be performed by extrusion molding using a twin-screw extruder at a temperature of 170 to 240°C, for example, 190 to 230°C.

[0140] The step of forming the above pellets into a sheet shape can be manufactured using a multilayer twin-screw extruder under extrusion molding temperature conditions of 170 to 240°C, for example, 190 to 230°C. At this time, multiple extruders can be used as melting sources to change the composition of the surface layer and the core, and a multilayer sheet can be formed by controlling the layer thickness by the flow rate using a feed block method.

[0141] The above pellet contains rHDPE but does not contain polybrominated biphenyls (PBBs) and polybrominated diphenyl ethers (PBDEs) compounds, and the weight ratio of the phosphite-based antioxidant to the oxide of the phosphite-based antioxidant may be 2.5 to 3:1 according to the analysis results by chromatography (HPLC).

[0142] In a specific example, in the step of manufacturing the pellet, the phosphite-based antioxidant may be further added in an amount equal to the weight ratio of the phosphite-based antioxidant oxide, and when the phosphite-based antioxidant is compensated for and pelletized, the subsequent process of forming into a sheet shape can be stabilized.

[0143] The above sheet can be cut into the shape of a ship hull part.

[0144] FIG. 3 is a nesting drawing for manufacturing a plate for a ship hull according to one embodiment of the present invention.

[0145] Referring to FIG. 3, the above-described eco-friendly ship hull plate can be manufactured by cutting the plate into the shape of a ship hull component according to a design (e.g., nesting drawing shown in FIG. 1) and then assembling (welding) the ship hull component. Such cutting and assembly (welding) methods are well known to those skilled in the art to which the present invention belongs. For example, the cutting method may be exemplified by a CNC method, a waterjet method, etc., but is not limited thereto.

[0146] In a specific example, the plate may have a thickness of 5 mm or more, for example, 5 to 100 mm, and a width of 500 mm or more, for example, 500 to 2,000 mm. Within the above range, depending on the application location on the hull, the design and fabrication of an eco-friendly ship hull may be facilitated.

[0147] The ship hull plate comprising the recycled high-density polyethylene resin and the ultra-high molecular weight polyethylene composite according to the present invention can replace virgin HDPE with rHDPE, thereby demonstrating environmental conservation effects such as resource recycling, reduction of plastic waste, and carbon reduction. Furthermore, it enables a practical approach to HDPE ship manufacturing by reducing raw material costs compared to virgin HDPE. In particular, the physical properties of rHDPE derived from engine oil containers among recycled HDPEs ensure mechanical strength and durability at the level required by ship structures, and the manufacturing efficiency is also high due to the stabilization of the process during the sheet forming process.

[0148] The composite of the above-mentioned rHDPE and UHMWPE has significantly improved tensile strength compared to conventional HDPE, which can enhance the structural strength of small vessels, and can improve the degree of freedom in designing the dimensions of major members by satisfying classification society standards with thinner plates.

[0149] The above-mentioned eco-friendly ship hull plate mixed with UHMWPE ensures heat resistance, thereby preventing problems such as fatigue or thermal deformation even when the size of the HDPE ship increases.

[0150] Since the above rHDPE does not contain brominated flame retardants (PBBs / PBDEs), there is no risk of toxic substances or equipment corrosion during welding, and it is possible to design thicker sheets; furthermore, because no pollutants are emitted when exposed to the outside air, the impact on the marine environment can be minimized.

[0152] 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.

[0154] Examples

[0155] The specifications of each component used in the examples and comparative examples below are as follows.

[0156] (A) complex

[0157] (A1) Ultra-high molecular weight polyethylene

[0158] Ultra-high molecular weight polyethylene (UHMWPE, Manufacturer: Daehan Petrochemical, Product Name: VH150U / U010PE500), density 0.94 g / cm³, weight-average molecular weight: 7,000,000 g / mol) was used.

[0159] (A2) Recycled high-density polyethylene

[0160] Recycled high-density polyethylene (HDPE) engine oil containers (Dongkwang Industries) were used. The HDPE bodies were sorted, labels and caps were removed, and the materials were washed with alkali, dried, and then crushed and pulverized. Subsequently, they were fed into a screw extruder and processed into pellets.

[0161] (A2-1)

[0162] General recycled HDPE was prepared using recycled high-density polyethylene.

[0163] Household and industrial HDPE mixed with detergents, lubricants, and food containers was collected by optical or manual sorting, crushed, alkali-washed, and dried, then processed into pellet form using a screw extruder.

[0165] (A3) High-density polyethylene

[0166] High-density polyethylene (HDPE, manufacturer: Lotte Chemical, product name: 5200B), density 0.963 g / cm³, weight-average molecular weight: approximately 250,000 g / mol) was used.

[0168] (B) Carbon material

[0169] Carbon black (Manufacturer: Burra Carbon, Product Name: Raven UV Ultra) was used.

[0171] (C) Light stabilizer

[0172] A light stabilizer (1,6-Hexanediamine, N,N'-Bis(2,2,6,6-tetramethyl-4-4piperidinyl)-,Polymers with 2,4-Dichloro-6-(4-morpholinyl)-1,3,5-triazine, Manufacturer: Scienceco, Product Name: UV3346) was used.

[0174] (D) Antioxidant

[0175] Pentaerythritol tetrakis [3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate] (Manufacturer: Ciba Specialty Chemicals, Product Name: Irganox 1010) and tris(2,4-di-t-butylphenyl)phosphite (Manufacturer: Ciba Specialty Chemicals, Product Name: Irgafos 168) were mixed (mixing ratio (Irganox 101:Irgafos 1680) = 1:1.5) and used.

[0177] Examples 1~6 and Comparative example 1~3

[0178] After adding each of the above components in the amounts listed in Table 1 below, pellets were manufactured by extrusion at approximately 220°C. A twin-screw extruder with L / D=36 and a diameter of 45 mm was used for extrusion. The manufactured pellets were dried at 80°C for at least 2 hours, and then specimens were manufactured by injection molding using a 220-ton injection molding machine (molding temperature: 220°C, mold temperature: 40°C). The physical properties of the manufactured specimens were evaluated using the following method, and the results are shown in Table 1 below.

[0180] Methods for measuring physical properties

[0181] (1) Density (unit: g / cm³)3 The density of the sheet was measured by the underwater displacement method (after 24 hours) in accordance with ASTM D792.

[0182] (2) Melt-flow Index (Unit: g / 10 min): According to ISO 1133, the Melt-flow Index (MFR) was measured at 190°C and 2.16 kgf.

[0183] (3) Tensile strength (unit: MPa): The tensile strength of a 3.2 mm thick specimen was measured according to ASTM D638.

[0184] (4) Flexural strength (unit: MPa): The flexural strength of a 3.2 mm thick specimen was measured according to ASTM D790.

[0185] (5) Flexural modulus (unit: MPa): The flexural modulus of a 3.2 mm thick specimen was measured according to ASTM D790.

[0186] (6) Notched Izod impact strength (unit: J / m): According to ASTM D256, the notched Izod impact strength (0℃, -10℃) of a 3.2 mm thick specimen was measured at -20℃.

[0187] (7) Heat deformation temperature (unit: ℃): The heat deformation temperature was measured when a deformation of 0.254 mm occurred on the surface of the specimen according to ASTM D640.

[0188] (9) Heavy metals in the specimens were detected using ICP-OES in accordance with IEC 62321-5:2013 and hazardous components PBBs / PBDEs were detected using GC / MS in accordance with IEC 62321-6:2015 (RoSH test).

[0190] Examples Comparative example 1 2 3 4 5 6 1 2 3 (A1) 10.6 15.9 20 30 - - - - - (A2) 89.4 84.1 80 70 70 80 100 - - (A2-1) - - - - - - 100 - (A3) - - - 30 20 - - 100 (B) 2.12 2.12 2.12 2.12 2.12 2.12 2.12 2.12 2.12 (C) 0.21 0.21 0.21 0.21 0.21 0.21 0.21 0.21 0.21 (D) 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 density 0.948 0.949 0.951 0.953 0.950 0.951 0.949 0.954 0.959 Melt index 0.21 0.18 0.15 0.13 0.22 0.23 0.26 0.45 0.23 tensile strength 28 29 31 33 27.3 26.1 23.5 22 27.3 Flexural strength 27.3 28.1 30.7 32.4 26.1 25.3 22 21.2 26.1 Flexural modulus 1,568 1,621 1,689 1,791 1,516 1,460 1,381 1,251 1,423 Notched Izod impact strength (0℃) 412 423 453 461 271 261 245 179 389 harmful ingredients N / A N / A N / A N / A N / A N / A N / A ○ N / A Plasticity ○ ○ ○ ○ ○ ○ ○ ○ ○ Weather resistance ○ ○ ○ ○ ○ ○ × × × weldability ○ ○ ○ ○ ○ ○ × × ○

[0191] In Table 1 above, the content unit is parts by weight.

[0192] From the results of Table 1 above, the hull plate material for a ship according to the embodiment of the present invention uses ultra-high molecular weight polyethylene and recycled high-density polyethylene in a specific ratio instead of the FRP material used in conventional small ships, and has excellent tensile strength and flexural strength, satisfying the standards presented by the Korean Register of Shipping (tensile strength 24 MPa or more, flexural strength 25 MPa or more).

[0193] It exhibits excellent flexural modulus and low-temperature notched Izod impact strength (0℃), demonstrating not only low-temperature rigidity but also heat resistance, satisfying all criteria set by the Korean Register of Shipping.

[0194] The examples confirmed that there is no environmental burden even when using recycled HDPE, as no hazardous components (RoSH) were detected, and confirmed that weldability is very high depending on density and melt index.

[0195] On the other hand, in Comparative Example 1, which did not use ultra-high molecular weight polyethylene, it was confirmed that mechanical properties such as tensile strength and impact strength were lower than those of the example. In Comparative Example 2, which used general recycled HDPE rather than recycled HDPE derived from engine oil, it was confirmed that the environmental burden increased due to the inclusion of trace amounts of catalyst components such as Ti and Mg, as well as flame retardant components of PBBs / PBDEs. In Comparative Example 3, when only virgin HDPE was used, the target weather resistance could not be achieved.

[0197] Origin of engine oil Recycling HDPE analyze

[0198] division Test method unit Korean Classification Society's proposed standards Recycled HDPE measurements Melt Index (MFR) ISO 1133 g / 10min 0.030 to 10(190℃ / 2.16kg) 0.26 density ASTM D792 g / cm3 0.946 to 0.972 0.949 tensile strength ASTM D638 MPa min.24 25.2 Yield elongation ASTM D638 MPa 1.0 to 27 10.1 Elongation at break ASTM D638 % 10 to 1,500 40.8 Flexural strength ASTM D790 MPa min.24 24.6 Flexural modulus ASTM D790 MPa min.750 953.2 Izod impact strength (0℃) ASTM D256 J / m min.196J / m(0℃) 247

[0199] As a result of verifying the physical properties of rHDPE according to the example, it was confirmed that they satisfy all the standards presented by the Korean Register of Shipping, and it was confirmed that eco-friendly ship hull plates can be manufactured using rHDPE.

[0200] Figure 4 is a graph showing the results of high-performance liquid chromatography (HPLC) analysis of recycled high-density polyethylene included in a ship hull plate according to one embodiment of the present invention.

[0201] division I-1010 I-1076 I-168 Inactive I-168 (oxidized) ppm 873.2 148.9 690.1 240.8

[0202] As a result of analyzing the recycled high-density polyethylene (A2) of the example, phenolic primary antioxidants I-1010 and I-1076 and phosphite secondary antioxidant I-168 were identified in Figure 4 and Table 3. In particular, oxidized and deactivated I-168 was present at 240.8 ppm, confirming that the rHDPE used a peroxide decomposition agent and had a history of heat or oxygen stress. This indicates that the rHDPE according to the example is distinguished from HDPE and recycled HDPE that are typically used for ship hulls.

[0203] It was confirmed that rHDPE according to the example has a reduced content of secondary oxidizing agent capable of removing peroxides generated during the subsequent high-temperature injection process, and thus problems such as viscosity reduction, yellowing, or oxidation being accelerated by residual metallic components may occur during processing, so it is desirable to supplement the secondary oxidizing agent.

[0204] FIG. 5 is a table showing the results of an analysis of the restriction of hazardous substances in recycled high-density polyethylene included in a ship hull plate according to one embodiment of the present invention.

[0205] Referring to FIG. 5, the rHDPE according to the embodiment was analyzed by ICP-OES in accordance with IEC 62321-5:2013 and by UV / VIS in accordance with IEC 62321-7-2:2017, and the results showed Pb, Cd, Hg, and Cr 2+ Heavy metals such as [unclear] were not detected. In addition, according to IEC 62321-6:2015, GC / MS analysis results showed that brominated flame retardants (PBBs / PBDEs) were not present and no harmful substances were detected, confirming that it can be used for eco-friendly ship hulls.

[0206] 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. Explanation of the symbols

[0208] 100 : Center 110: First surface layer 120 : Second surface layer

Claims

Claim 1 A plate for a ship hull comprising a composite including high-density polyethylene and ultra-high molecular weight polyethylene, wherein the high-density polyethylene includes recycled high-density polyethylene, the weight ratio of the ultra-high molecular weight polyethylene to the high-density polyethylene is 10 to 30: 90 to 70, and the recycled high-density polyethylene has a yield stress of 25.2 MPa or more as measured according to ASTM D638, a breaking strength of 16.3 MPa or more as measured according to ASTM D638, a flexural strength of 24.6 MPa or more as measured according to ASTM D790, and a flexural modulus of 953.2 MPa or more as measured according to ASTM D790. Claim 2 A plate for a ship hull according to claim 1, wherein the high-density polyethylene is recycled high-density polyethylene alone. Claim 3 A plate for a ship hull according to claim 1, wherein the high-density polyethylene is a mixture of recycled high-density polyethylene and virgin high-density polyethylene. Claim 4 In claim 1, the recycled high-density polyethylene is derived from one or more of engine oil containers, detergent containers, and milk containers, and is a plate for a ship hull. Claim 5 In claim 1, the recycled high-density polyethylene has a melt index (MI) of 0.26 g / 10 min or less as measured according to ISO 1133, and a density of 0.949 g / cm³ as measured according to ASTM D792. 3 A plate for a ship hull that is the above. Claim 6 delete Claim 7 A plate for a ship hull according to claim 1, wherein the recycled high-density polyethylene has a notched Izod impact strength (0°C) of 350 J / m or more and a notched Izod impact strength (-10°C) of 245 J / m or more as measured according to ASTM D256. Claim 8 A plate for a ship hull according to claim 1, wherein the recycled high-density polyethylene contains 230 to 250 ppm of oxide of a phosphite-based antioxidant as a result of analysis by high-performance liquid chromatography (HPLC). Claim 9 A plate for a ship hull according to claim 1, wherein the recycled high-density polyethylene has a weight ratio of a phosphite-based antioxidant to an oxide of the phosphite-based antioxidant of 2.5 to 3:1 as a result of analysis by high-performance liquid chromatography (HPLC). Claim 10 A plate for a ship hull according to claim 9, wherein the phosphite-based antioxidant is further added in an amount equal to the weight ratio of the oxide of the phosphite-based antioxidant. Claim 11 A ship hull plate according to claim 1, wherein the ship hull plate comprises 0.1 wt% or less of polybrominated biphenyl (PBBs) and polybrominated diphenyl ether (PBDEs) compounds. Claim 12 A plate for a ship hull according to claim 1, further comprising, with respect to 100 parts by weight of the composite, 0.01 to 5 parts by weight of a light stabilizer; 0.01 to 4 parts by weight of a carbon material; and 0.01 to 2 parts by weight of an antioxidant. Claim 13 A method for manufacturing a plate for a ship hull, comprising the steps of: manufacturing a pellet including high-density polyethylene and ultra-high molecular weight polyethylene; forming the pellet into a sheet; and cutting the sheet into a ship hull part; wherein the high-density polyethylene includes recycled high-density polyethylene, and the weight ratio of the ultra-high molecular weight polyethylene to the recycled high-density polyethylene is 10 to 30: 90 to 70. Claim 14 A method for manufacturing a plate for a ship hull according to claim 13, wherein the step of manufacturing the pellets is to extrude them at a temperature of 170 to 240°C using a twin-screw extruder. Claim 15 A method for manufacturing a plate for a ship hull according to claim 13, wherein the pellet does not contain polybrominated biphenyls (PBBs) and polybrominated diphenyl ethers (PBDEs) compounds. Claim 16 A method for manufacturing a plate for a ship hull according to claim 13, wherein the pellet has a weight ratio of a phosphite-based antioxidant to an oxide of the phosphite-based antioxidant of 2.5 to 3:1 as a result of analysis by chromatography (HPLC). Claim 17 A method for manufacturing a plate for a ship hull according to claim 16, wherein the phosphite-based antioxidant is further added in an amount equal to the weight ratio of the phosphite-based antioxidant oxide.

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