Multilayer interior material with unpainted color reproducibility and self-healing property and method for manufacturing the same

Abstract

The present invention relates to a multilayer interior material comprising: a core layer comprising a first resin composition containing recycled raw materials derived from a gimbaljang; and a skin layer comprising a second resin composition having scratch concealment and self-restoration performance, and a method for manufacturing the same. According to the present invention, by forming a multilayer structure of a core layer formed using a gimbaljang as a raw material and a skin layer made using a resin having scratch concealment and self-restoration characteristics, paintless color reproducibility, appearance uniformity, physical property stabilization, and scratch restoration performance can be secured, and the degree of design freedom can be increased.

Description

Technology Field

[0001] The present invention relates to a multilayer interior material having unpainted color reproducibility and self-restoring properties and a method for manufacturing the same. More specifically, by forming a multilayer structure of a core layer formed using discarded seaweed drying racks as a raw material and a skin layer made using a resin having scratch concealing and self-restoring properties, the invention secures unpainted color reproducibility, appearance uniformity, physical property stabilization, and scratch restoration, and increases design freedom. Background Technology

[0003] Global efforts are underway to reduce carbon dioxide emissions associated with global warming, and as part of this initiative, Asian and European Union countries have announced plans to significantly reduce or halt the production of internal combustion engine vehicles after 2025. Domestically, efforts to reduce greenhouse gases are also being carried out at the national level, and significant efforts are being devoted to the development of eco-friendly plastic materials.

[0004] As interest in the eco-friendly automotive industry increases, research and development is being conducted to enhance environmental sustainability not only in fuel but also in terms of vehicle interiors, parts, and materials. Major domestic and international automakers are strengthening technological development in various areas, such as materials and processing techniques, and there is a growing volume of diverse research and development aimed at practicing resource circularity by utilizing eco-friendly materials, including natural raw materials and recycled materials.

[0005] Representative examples of eco-friendly recycled materials are those derived from various plastics. In particular, polyolefins such as polyethylene or polypropylene are widely applied in diverse fields including food, textiles, automotive parts, and packaging for various goods, and multifaceted development is underway to consider environmental impacts regarding disposal, collection, and recycling.

[0006] However, compared to virgin materials, recycled polyolefins exhibit lower stiffness, impact strength, and mechanical properties, as well as poor performance in terms of odor or appearance contamination. Consequently, they fail to meet the physical property requirements for applications in automotive parts or household goods, leading to limitations in material selection. Furthermore, recycled polyolefin materials can typically be cross-contaminated by non-polyolefin materials such as polyethylene terephthalate, polyamide, and polystyrene, or by non-polymeric materials such as wood, paper, glass, or aluminum. These additional impurities act as factors that impair the compatibility of recycled polyolefins. Therefore, to improve the characteristics of recycled polyolefin materials, research is being conducted on combining them with virgin polyolefin materials or applying additives such as various compatibilizers and coupling agents.

[0007] Automotive interior materials often feature a multilayer structure consisting of a skin layer and a core layer, and such materials can be manufactured using conventional multilayer molding processes. Furthermore, there is growing interest in paintless automotive interior materials, which are used in their molded state without forming a paint layer, in terms of cost reduction and enhanced eco-friendliness.

[0008] In multilayer molding, the characteristics of the core layer significantly influence the color of the skin layer. Particularly when paintless or multi-color specifications are required, the color of the skin layer is greatly affected by the material of the core layer; therefore, there is a need to develop core layers that enable the realization of a stable appearance and the reproducibility of paintless colors.

[0009] Generally used recycled polypropylene has inconsistent physical properties, purity, and color tone from lot to lot, so when applied as a core layer in a multilayer structure, it is difficult to ensure color reproducibility and surface uniformity of the skin layer.

[0010] Furthermore, thermoplastic resins are commonly used as skin layers due to their advantages, such as excellent moldability, low production costs, ease of recycling, and compatibility with various molding processes (injection, extrusion, blow molding, etc.). However, despite the expanded use of these thermoplastic resins, there is a problem in that their surface durability is lower than that of metals or glass, making them susceptible to scratches caused by external forces and consequently degrading appearance quality. In particular, for unpainted thermoplastic surfaces such as those used in automotive interior and exterior materials, a so-called "visual scratch" phenomenon occurs when a scratch causes an immediate excessive increase in brightness, making the scratched area appear brighter than the surrounding area. Additionally, even after time has passed since the scratch occurred, the difference in brightness often does not decrease sufficiently, resulting in a lack of visual concealment.

[0011] To address this, conventional technologies have been proposed to improve scratch resistance and appearance quality by forming a coating or paint layer on the resin surface. However, these coating and painting processes have limitations, such as increased process complexity, higher costs, and environmental issues arising from the generation of volatile organic compounds (VOCs) and volatile condensed gases (FOGs). Furthermore, problems arise regarding reduced recyclability due to the multilayer structure and incompatibility with molding processes. Meanwhile, self-healing technologies utilizing encapsulated healing agents or crosslinking reaction systems are also being studied; however, it is difficult to ensure uniform healing and repeated durability, and side effects such as additive migration (blooming) or reduced moldability are prone to occur.

[0012] Patent Document 1 relates to a self-healing microcapsule having a core-shell structure and a method for manufacturing the same, and discloses a self-healing microcapsule having a core-shell structure comprising linseed oil as a self-healing material and a composite film comprising a polymer matrix in which the capsule is dispersed.

[0013] Patent Document 2 relates to a recycling processing device for seaweed drying racks, and discloses a processing device that provides the advantage of improving the separation efficiency of foreign substances from seaweed drying racks as well as improving the separation efficiency of drying tubes and supports.

[0014] Conventional technology refers to technical information that the inventor possessed for the derivation of the present invention or acquired during the process of deriving the present invention, and it cannot necessarily be considered publicly known technology disclosed to the general public prior to the filing of the present invention. Prior art literature

[0016] Republic of Korea Published Patent No. 10-2023-0169025 (Published Dec. 15, 2023) Republic of Korea Registered Patent No. 10-2746627 (Registered Dec. 20, 2024) The problem to be solved

[0017] In resolving the aforementioned problems, the objective of the present invention is to provide a multilayer interior material having paint-free color reproducibility and self-restoring properties, capable of increasing the purity of the seaweed sheet used as a raw material for the core layer, reducing variations in physical properties, foreign substances, and odors to improve surface uniformity, securing rigidity and heat resistance, and configuring a background tone similar to the color of the skin layer, as well as a method for manufacturing the same.

[0018] In addition, the objective of the present invention is to provide a multilayer interior material having unpainted color reproducibility and self-healing properties that visually conceal scratches and efficiently self-heal, allowing for visual return to the skin layer color when scratches occur, and a method for manufacturing the same.

[0019] Furthermore, the objective of the present invention is to provide a multilayer interior material having paint-free color reproducibility and self-restoring properties, and a method for manufacturing the same, which can be efficiently manufactured by a conventional multilayer molding process without separate additional processes or increased costs, and which can increase the design freedom of structure and rigidity.

[0020] The problems that the present invention aims to solve are not limited to those mentioned above, and other problems not mentioned will be clearly understood by a person skilled in the art to which the present invention belongs from the description below. means of solving the problem

[0022] A multilayer interior material according to an embodiment of the present invention comprises: a core layer comprising a first resin composition comprising recycled raw materials derived from a seaweed drying rack; and a skin layer comprising a second resin composition having scratch concealment and self-restoration performance.

[0023] In one embodiment, the recycled raw material may include HCPP (High Crystalline Polypropylene) resin and a filler.

[0024] In one embodiment, the filler may be selected from the group consisting of talc, carbon black, calcium oxide, magnesium oxide, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium carbonate, magnesium carbonate, calcium silicate, magnesium silicate, calcium sulfate, barium sulfate, calcium sulfite, mica, clay, dolomite, glass beads, glass fibers, and combinations thereof.

[0025] In one embodiment, the recycled raw material may be included in a range of 30 to 70 weight percent based on the total weight of the core layer.

[0026] In one embodiment, the first resin composition may include a recycled raw material derived from the seaweed drying rack and a first thermoplastic resin.

[0027] In one embodiment, the first thermoplastic resin may be selected from the group consisting of PP (Polypropylene), PE (Polyethylene), ABS (Acrylonitrile Butadiene Styrene), PC (Polycarbonate), PA (Polyamide), PET (Poly(ethylene terephthalate)), PVC (Polyvinyl chloride), TPO (Thermoplastic olefin) and combinations thereof.

[0028] In one embodiment, the core layer may have a color that matches the color of the skin layer to satisfy a preset ΔE value.

[0029] In one embodiment, the color of the core layer can be controlled using the color of recycled raw material derived from the seaweed drying rack.

[0030] In one embodiment, the second resin composition comprises a second thermoplastic resin and an additive, wherein the second thermoplastic resin comprises a urethane resin comprising a hard segment derived from a diisocyanate and a soft segment derived from a polyol, and the additive may each comprise at least one hydrogen bond donor functional group and an acceptor functional group.

[0031] In one embodiment, the hydrogen bond donating functional group comprises at least one selected from the group consisting of an amino group (-NH2), an imino group (-NH-), and a hydroxyl group (-OH), and the hydrogen bond accepting functional group may be at least one selected from the group consisting of a carbonyl group (C=O), a thiocarbonyl group (C=S), an ether group (-O-), an amide group (-CONH-), and an isocyanurate group (-NCO-).

[0032] In one embodiment, the diisocyanate comprises at least one selected from the group consisting of aliphatic, alicyclic, aliphatic-aliphatic, and aromatic diisocyanate compounds, and the polyol may be at least one selected from the group consisting of polyether polyol, polyester polyol, and polycarbonate polyol.

[0033] In one embodiment, the diisocyanate comprises at least one selected from the group consisting of methylenebis(phenylisocyanate) (MDI), hexamethylene diisocyanate (HDI), and isophorone diisocyanate (IPDI), and the polyol may be at least one selected from the group consisting of polytetramethylene glycol (PTMG), polycaprolactone diol (PCL), and polycarbonate diol (PCD).

[0034] In one embodiment, the weight ratio of the hard segment to the soft segment in the second thermoplastic resin may be in the range of 30:70 to 60:40.

[0035] In one embodiment, the additive may be included in an amount of 0.1 to 10 weight% based on the total weight of the second resin composition.

[0036] In one embodiment, the additive may be at least one selected from the group consisting of urea-based compounds, carbamate-based compounds, isocyanurate-based compounds and amide-based compounds.

[0037] In one embodiment, the urea-based compound may be at least one selected from the group consisting of thiourea, 1,3-bis(3-aminopropyl)urea, N,N'-diphenylurea, and bis(4-aminophenyl)urea.

[0038] In one embodiment, the additive may have a weight-average molecular weight in the range of 200 to 5,000 g / mol.

[0039] In one embodiment, the skin layer may exhibit self-healing properties in a temperature range of 20 to 80°C.

[0040] A method for manufacturing a multilayer interior material according to an embodiment of the present invention comprises: a raw material manufacturing step of processing discarded seaweed drying racks to form recycled raw materials; a first resin composition forming step of forming a first resin composition containing the recycled raw materials; a second resin composition forming step of forming a second resin composition having scratch concealment and self-restoration performance; and a multilayer structure forming step of forming a core layer containing the first resin composition and a skin layer containing the second resin composition by a multilayer molding process.

[0041] In one embodiment, the raw material manufacturing step may be carried out by a method comprising: a crushing and separation step; a washing and screening step; a dehydration step; and an extrusion step.

[0042] In one embodiment, the step of forming a multilayer structure may be performed by a method selected from the group consisting of multilayer injection molding, multilayer extrusion molding, lamination, and combinations thereof. Effects of the invention

[0044] As described above, according to an embodiment of the present invention, a multilayer interior material having unpainted color reproducibility and self-restoring properties and a method for manufacturing the same provide a method for manufacturing the same that increases the purity of the seaweed sheet used as a raw material for the core layer, reduces variations in physical properties, foreign substances, and odor to improve surface uniformity, secures rigidity and heat resistance, and can form a background tone similar to the color of the skin layer.

[0045] In addition, according to the multilayer interior material having unpainted color reproducibility and self-restoring properties and the method for manufacturing the same according to an embodiment of the present invention, scratches can be visually concealed and self-restored efficiently so that visual return to the skin layer color can be achieved when scratches occur.

[0046] In addition, according to the multilayer interior material having paint-free color reproducibility and self-restoring properties and the method for manufacturing the same according to an embodiment of the present invention, it can be efficiently manufactured by a conventional multilayer molding process without separate additional processes or increased costs, and the design freedom of structure and rigidity can be increased.

[0047] The effects of the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by a person skilled in the art to which the present invention pertains from the description below. Brief explanation of the drawing

[0049] FIG. 1 is a schematic diagram showing a multilayer interior material according to an embodiment of the present invention. FIG. 2 is a schematic diagram showing a gimbal used in the core layer of a multilayer interior material according to an embodiment of the present invention. FIGS. 3 and 4 are schematic diagrams illustrating the self-healing process that occurs when a crack occurs in the skin layer of a multilayer interior material according to an embodiment of the present invention. FIG. 5 is a schematic diagram illustrating the dispersion of additives and the formation of a hydrogen bond network in the skin layer of a multilayer interior material according to an embodiment of the present invention. FIG. 6 is a flowchart illustrating a method for manufacturing a multilayer interior material according to an embodiment of the present invention. FIG. 7 is a flowchart showing a processing method of a seaweed sheet used as a raw material for the core layer among the manufacturing methods of a multilayer interior material according to an embodiment of the present invention. Specific details for implementing the invention

[0050] In the present invention, the attached drawings may be illustrated with exaggerated expressions to distinguish it from the prior art, ensure clarity, and facilitate the understanding of the technology. Furthermore, the terms described below are defined considering their functions in the present invention; since these terms may vary depending on the intentions or conventions of the user or operator, their definitions should be based on the technical content throughout this specification. Meanwhile, the embodiments are merely exemplary details of the components presented in the claims of the present invention and do not limit the scope of the rights of the present invention; the scope of rights should be interpreted based on the technical concept throughout the specification of the present invention.

[0051] Throughout the specification, when a configuration is described as "including" a configuration, this means that, unless specifically stated otherwise, it does not exclude other configurations but may include additional configurations.

[0052] Furthermore, when it is said that one configuration is "connected," "connected," or "combined" with another configuration, this means that it is not only "directly connected," "directly connected," or "directly combined," but also that there may be cases where it is "connected with another configuration interposed," "connected with another configuration interposed," or "combined with another configuration interposed." On the other hand, when it is said that one configuration is "directly connected," "directly connected," or "directly combined" with another configuration, it should be understood that there is no other configuration in between.

[0053] In addition, when directional terms such as "front," "back," "up," "down," "left," "right," "first end," "other end," and "both ends" are used, they are used exemplarily in relation to the orientation of the disclosed drawings and should not be interpreted restrictively, and when terms such as "first" and "second" are used, they are terms used to distinguish each configuration and should not be interpreted restrictively.

[0054] In order to more clearly explain the features of the embodiments of the present invention, detailed descriptions of matters widely known to those skilled in the art to which the following embodiments pertain are omitted. Additionally, detailed descriptions of parts in the drawings that are unrelated to the description of the embodiments are omitted.

[0055] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings.

[0057] FIG. 1 is a schematic diagram showing a multilayer interior material according to an embodiment of the present invention, FIG. 2 is a schematic diagram showing a seaweed sheet used in the core layer of a multilayer interior material according to an embodiment of the present invention, FIG. 3 and FIG. 4 are schematic diagrams showing a self-restoration process that occurs when a crack occurs in the skin layer of a multilayer interior material according to an embodiment of the present invention, FIG. 5 is a schematic diagram showing the dispersion of an additive and the formation of a hydrogen bond network in the skin layer of a multilayer interior material according to an embodiment of the present invention, FIG. 6 is a flowchart showing a method for manufacturing a multilayer interior material according to an embodiment of the present invention, and FIG. 7 is a flowchart showing a method for processing a seaweed sheet used as a raw material for the core layer in the method for manufacturing a multilayer interior material according to an embodiment of the present invention.

[0059] Referring to FIG. 1, a multilayer interior material (1) according to an embodiment of the present invention includes a core layer (10) and a skin layer (20).

[0060] The core layer (10) is placed inside the multilayer interior material (1), and the skin layer (20) is placed outside the core layer (10).

[0061] According to FIG. 1, the multilayer interior material (1) is formed as a sandwich structure. However, in another embodiment, the multilayer interior material (1) may be formed as a two-layer structure of a core layer (10) and a skin layer (20).

[0062] The above core layer (10) can serve to enable the multilayer interior material (1) to exhibit unpainted color reproducibility and surface uniformity.

[0063] The core layer (10) comprises a first resin composition, and the first resin composition comprises recycled raw materials derived from a seaweed drying rack.

[0064] A gimbaljang is a tool used to dry seaweed harvested from a seaweed farm. Traditionally, gimbaljangs were made by splitting bamboo into pieces of a certain size and weaving them with thread, but currently, they are made using synthetic resin.

[0065] Seaweed drying racks are used in approximately 300 seaweed manufacturing plants nationwide. Due to adverse conditions during use, such as being submerged in seawater and exposed to sunlight, their lifespan is short, resulting in a replacement cycle of only about 30 days. Discarded seaweed drying racks are subject to mandatory recycling, and manufacturers are required to take responsibility for their collection and recycling.

[0066] The seaweed drying rack has a short replacement cycle, so the physical properties of the recycled raw materials derived from it are excellent, there are no problems with foreign substances or odor generation, and in particular, it has the characteristic of not generating volatile organic compounds (VOCs). In addition, by recycling and utilizing materials that would otherwise be discarded as waste, it can enhance eco-friendliness, and since the processing is not as complex as other recycled materials, it is advantageous in terms of cost competitiveness. Furthermore, the recycled raw materials derived from the seaweed drying rack have high purity, exhibit excellent physical property stability, and can improve surface uniformity. Also, since the seaweed drying rack is operated in a multi-color lot, this can be utilized to control the core layer (10) to have a background tone similar to the color of the skin layer (20).

[0067] Referring to FIG. 2, the above-described seaweed rack (100) may include a first part (101) that occupies most of the interior, a second part (102) that is positioned on both sides of the first part (101), and a connecting part (103) that connects the seaweed racks constituting the first part (101) and the second part (102) to each other.

[0068] The first part (101) may include HCPP (High Crystalline Polypropylene) resin and a filler. The HCPP resin and filler may be included in an amount of 80 to 90 weight%, preferably 85 to 90 weight%, based on the total weight of the gimbal (100).

[0069] The second part (102) may include an ABS (Acrylonitrile Butadiene Styrene) resin. The ABS resin may be included in an amount of 5 to 15 weight percent, preferably 7 to 12 weight percent, based on the total weight of the seaweed rack (100).

[0070] The third part (103) may include PET (Poly(ethylene terephthalate)) fibers. The PET fibers may be included in an amount of 1 to 10 weight percent, preferably 1 to 5 weight percent, based on the total weight of the seaweed rack (100).

[0071] Since the above-mentioned seaweed drying rack (100) is operated in a multi-color lot, the recycled raw materials derived therefrom can have various colors.

[0072] In one embodiment, the first part (101) may be yellow, the second part (102) may be red, and the third part (103) may be white.

[0073] The recycled raw material derived from the above-mentioned seaweed drying rack (100) can be formed into flakes of each material by performing a process of crushing / separating, washing / sorting, dehydrating, and extruding the discarded seaweed drying rack (100).

[0074] In an embodiment of the present invention, recycled raw materials derived from the above-mentioned seaweed drying rack (100) are used as the material for the core layer (10).

[0075] The above recycled raw material may include HCPP resin and filler. That is, in an embodiment of the present invention, the recycled raw material used as the material of the core layer (10) may include HCPP resin and filler derived from the first part (101) separated / selected by performing a processing process on the discarded seaweed rack (100).

[0076] The above HCPP resin is a high-performance plastic material that has higher rigidity, heat resistance, and scratch resistance than general polypropylene. The above HCPP resin can exhibit excellent dimensional stability due to its high crystallinity.

[0077] The above HCPP resin can be applied in various ways, such as injection-molded products, extruded and heat-processed products, and wire width materials requiring high rigidity and impact resistance, including electrical and electronic components, automotive parts, and home appliance housings.

[0078] In one embodiment, the HCPP resin may include a chain-type polymer made by crosslinking PE to isotactic PP, which is a copolymer of PP and PE.

[0079] The above filler may be selected from the group consisting of talc, carbon black, calcium oxide, magnesium oxide, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium carbonate, magnesium carbonate, calcium silicate, magnesium silicate, calcium sulfate, barium sulfate, calcium sulfite, mica, clay, dolomite, glass beads, glass fibers, and combinations thereof.

[0080] In one embodiment, the recycled material may be included up to 70% by weight based on the total weight of the core layer (10). Thus, even if the core layer (10) contains a high amount of the recycled material, the variation in physical properties and purity of the seaweed sheet (100) is small, which increases the design freedom of the structure and rigidity of the core layer (10).

[0081] In one embodiment, the recycled material may be included in a range of 30 to 70 weight percent based on the total weight of the core layer (10). If the content of the recycled material is less than the above range, the effect of improving unpainted color reproducibility and surface uniformity may be insufficient, and if it exceeds the above range, the variation in physical properties may increase, causing problems in securing uniform characteristics.

[0082] In one embodiment, the recycled material may be included in a range of 50 to 70 weight percent based on the total weight of the core layer.

[0083] The first resin composition included in the core layer (10) may include the recycled raw material and the first thermoplastic resin.

[0084] The first thermoplastic resin can be appropriately selected according to the application field to which the multilayer interior material (1) is applied.

[0085] In one embodiment, the first thermoplastic resin may be selected from the group consisting of PP (Polypropylene), PE (Polyethylene), ABS (Acrylonitrile Butadiene Styrene), PC (Polycarbonate), PA (Polyamide), PET (Poly(ethylene terephthalate)), PVC (Polyvinyl chloride), TPO (Thermoplastic olefin) and combinations thereof.

[0086] In one embodiment, the first thermoplastic resin may include PP.

[0087] In one embodiment, the first thermoplastic resin may include one selected from the group consisting of homopolymer PP, random copolymer PP, impact copolymer PP, and combinations thereof.

[0088] In one embodiment, the first thermoplastic resin may be PP that does not contain HCPP.

[0089] In one embodiment, the core layer (10) may have a color that matches the color of the skin layer (20). That is, the color of the core layer (10) may be controlled to have a background tone similar to the color of the skin layer (20).

[0090] In this way, by controlling the color of the core layer (10) to match the skin layer (20), the exposure of color fluctuations or fine stains can be minimized, thereby increasing the unpainted color reproduction.

[0091] The color control of the core layer (10) can be achieved by using the color of the recycled material derived from the raw material, the gimbaljang (100). The gimbaljang (100) is operated in a multi-color lot, so the first part (101) can have various colors. Accordingly, the color of the core layer (10) can be controlled as desired by selecting a recycled material among the recycled materials derived from the gimbaljang (100) that has a color matching the color of the skin layer (20) to form the core layer (10).

[0092] In one embodiment, the color of the core layer (10) can be set by evaluating ΔE, which is an indicator that numerically expresses the difference between two colors.

[0093] ΔE is primarily calculated in the CIELAB color space, and a larger ΔE value indicates a greater color difference. In the CIELAB color space, the ΔE value between two colors is calculated using the Euclidean distance, which allows for a numerical comparison of the difference between the two colors.

[0094] An example of a rough guideline for the ΔE value is as follows.

[0095] ΔE = 0: The two colors are identical

[0096] ΔE < 0.4: Almost indistinguishable to the human eye

[0097] 0.4 < ΔE < 0.6: Tight management standards in large corporations

[0098] 0.6 < ΔE < 0.8: Color management range of adjacent parts

[0099] 0.8 < ΔE < 1.5: General Product Color Management

[0100] 1.5 < ΔE < 3.0: Managing the same color over a wide range

[0101] ΔE > 3.0: Range where claims may arise due to color differences

[0102] ΔE > 12: Range perceived as a completely different color

[0103] In an embodiment of the present invention, the color of the core layer (10) can be matched with the color of the skin layer (20) by setting the color of the core layer (10) to satisfy a preset ΔE value.

[0104] The skin layer (20) comprises a second resin composition. The second resin composition may have scratch concealment and self-healing performance.

[0105] The second resin composition may include a second thermoplastic resin and an additive.

[0106] The second resin composition according to an embodiment of the present invention has a thermoplastic resin as a matrix and contains an additive having a multi-point hydrogen bonding functional group, so that even if hydrogen bonds near the surface are temporarily broken when scratches or cracks occur, the hydrogen bonding network between the additive and the resin is reformed under room temperature or low temperature heat treatment conditions, thereby rearranging the molecular chains.

[0107] According to one embodiment, the second resin composition may exhibit self-healing properties in a temperature range of 20 to 80°C. This temperature range is sufficient to promote the reformation of hydrogen bond networks in an ambient temperature environment without an external heat source or under low-temperature heat treatment conditions, enabling rapid and stable surface recovery without a separate high-temperature process. Accordingly, visual concealment and self-healing effects can be exhibited, in which surface continuity is restored, light scattering is reduced, and the difference in brightness (ΔL) is rapidly reduced. The second thermoplastic resin provides the basic mechanical strength and moldability of the composition, and the additive induces reversible rearrangement of the surface structure by forming a non-covalent network with the molecular chains of the resin through the interaction between hydrogen bond donors and acceptors. Through this interaction, the resin and the additive form a single integrated physical network, which can maximize self-healing performance by improving responsiveness to external forces or thermal stimuli.

[0108] The second thermoplastic resin mentioned above refers to a resin having the physical properties of melting upon heating to enable molding and solidifying again upon cooling. Since this second thermoplastic resin enables repetitive molding through reversible physical changes, it can be applied to general processing processes such as injection molding, extrusion, and compression molding. In particular, unlike thermosetting resins, chemical crosslinking does not occur during the heating and cooling processes; therefore, in the embodiments of the present invention, non-covalent hydrogen bonding interactions with additives can be effectively expressed. Accordingly, the second thermoplastic resin provides a basis for simultaneously securing excellent processability as well as surface recovery after scratching.

[0109] The second thermoplastic resin comprises a urethane-based resin comprising a hard segment derived from a diisocyanate and a soft segment derived from a polyol. Preferably, the thermoplastic resin may be the urethane-based resin.

[0110] In one embodiment, the second thermoplastic resin may have a block copolymer structure comprising hard segments and soft segments. Preferably, the second thermoplastic resin may be a thermoplastic polyurethane (TPU) having a block copolymer structure. The second thermoplastic resin exists stably as a solid at room temperature but melts upon heating to enable remolding. The hard segments serve to impart mechanical strength, thermal stability, elastic recovery, and scratch resistance to the resin, and may mainly comprise reaction products of diisocyanates and chain extenders. The soft segments serve to control the flexibility, shock absorption, low-temperature properties, and self-restoring properties of the resin, and are derived from polyol components. In this block-structured thermoplastic urethane resin, the hard segments and soft segments form a microphase-separated structure, allowing for partial rearrangement of the hydrogen bond network through non-covalent interactions with additives in the present invention, thereby effectively inducing a self-restoring reaction.

[0111] The second thermoplastic resin may additionally include a chain extender as needed. The chain extender controls the chain length of the intermediate in the reaction between the diisocyanate and the polyol, and increases the bonding density of the hard segments to improve mechanical strength and thermal stability. Generally, low molecular weight (molecular weight about 60 to 300) diols or diamines may be used as chain extenders, and specific examples include 1,4-butanediol, ethylene glycol, diethylene glycol, or ethylene diamine. Such chain extenders can contribute to simultaneously improving the self-healing stability and scratch resistance of the second resin composition by strengthening the hydrogen bonding network between the hard segments.

[0112] In one embodiment, the diisocyanate may be at least one selected from the group consisting of aliphatic, alicyclic, aliphatic-alicyclic, and aromatic diisocyanate compounds. Here, an aliphatic-alicyclic diisocyanate compound refers to a diisocyanate in which both an aliphatic chain and an alicyclic ring structure exist within one molecule.

[0113] In one embodiment, the diisocyanate may be at least one selected from the group consisting of methylenebis(phenylisocyanate) (MDI), hexamethylene diisocyanate (HDI), and isophorone diisocyanate (IPDI). Since aromatic compounds are advantageous for increasing hardness and stiffness, aliphatic compounds have excellent resistance to yellowing and transparency, and alicyclic compounds have excellent heat resistance and light resistance, the balance of physical properties can be precisely controlled by selecting the diisocyanate compound or adjusting the mixing ratio.

[0114] In one embodiment, the polyol may be at least one selected from the group consisting of polyether polyol, polyester polyol, and polycarbonate polyol. The polyol can optimize the balance between thermal stability and self-restoring properties.

[0115] In one embodiment, the polyol may be at least one selected from the group consisting of polytetramethylene glycol (PTMG), polycaprolactone diol (PCL), and polycarbonate diol (PCD).

[0116] In one embodiment, the weight ratio of the hard segment and the soft segment of the second thermoplastic resin may be in the range of 30:70 to 60:40. When the above range is satisfied, structural rigidity and self-restoring properties can be secured in balance, and the effect of improving the surface brightness recovery rate can be obtained.

[0117] In one embodiment, the second thermoplastic resin may be included in an amount of 90 to 99.9 weight percent of the total composition. Within this range, the interaction between the second thermoplastic resin and the additive is stably formed, thereby ensuring mechanical properties and optimizing the balance between recovery speed, scratch resistance, and optical opacity.

[0118] The weight-average molecular weight (Mw) of the second thermoplastic resin may be in the range of 30,000 to 500,000 g / mol, preferably 50,000 to 300,000 g / mol. When the above range is satisfied, the reformation of the hydrogen bond network and the reversible movement of the molecular chain are balanced, thereby ensuring excellent self-restoring properties and moldability simultaneously. The weight-average molecular weight (Mw) can be measured using gel permeation chromatography (GPC) and can be calculated by using tetrahydrofuran (THF) as a solvent and correcting based on polystyrene standards.

[0119] The above additive serves to restore severed bonds and recover surface continuity upon scratching by forming and reforming a non-covalent multifunctional hydrogen-bonding network at the surface or interface region of the second thermoplastic resin. Through this interaction, molecular chains are realigned, and light scattering is reduced, resulting in a rapid reduction of the brightness difference (ΔL).

[0120] The additive used in the present invention may be a compound having a multi-point hydrogen bonding functional group. Specifically, the additive used in the present invention may be a compound comprising at least one hydrogen bond donor functional group and at least one hydrogen bond accepting functional group. The hydrogen bond donor functional group may form a bonding network by providing a hydrogen atom within the molecule and interacting with an electronegative atom in an adjacent molecule or within the same molecule, while the hydrogen bond accepting functional group plays a role in accepting a bond by interacting with hydrogen from the donor through an atom possessing an electron pair (e.g., oxygen, nitrogen, sulfur, etc.). By including a multi-point hydrogen bonding functional group capable of multiple interactions, the additive can increase bonding stability and recovery speed compared to a single hydrogen bond, and provide the effect of rapidly reducing surface brightness differences.

[0121] The hydrogen bond donor functional group may be at least one selected from the group consisting of an amino group (-NH₂), an imino group (-NH-), and a hydroxyl group (-OH), and the hydrogen bond acceptor functional group may be at least one selected from the group consisting of a carbonyl group (C=O), a thiocarbonyl group (C=S), an ether group (-O-), an amide group (-CONH-), and an isocyanurate group (-NCO-).

[0122] In one embodiment, the additive may be at least one selected from the group consisting of urea-based compounds, carbamate-based compounds, isocyanurate-based compounds, and amide-based compounds.

[0123] In one embodiment, the urea-based compound may be at least one selected from the group consisting of thiourea, 1,3-bis(3-aminopropyl)urea, N,N'-diphenylurea, and bis(4-aminophenyl)urea, and the compound may include both a hydrogen bond donor and a acceptor, enabling multi-point interaction with the resin.

[0124] The above additive is chemically stable at a mixing temperature, preferably in the temperature range of 150 to 230°C, and can stably maintain its hydrogen bonding function even during repeated heating processes without decomposition or discoloration.

[0125] In one embodiment, the content of the additive may be in the range of 0.1 to 10 weight% or 0.1 to 5 weight% based on the total weight of the second resin composition. When the above range is satisfied, the additive is uniformly dispersed within the resin to provide sufficient bonding sites while suppressing phase separation or viscosity increase, thereby ensuring excellent molding stability and self-restoring effects simultaneously.

[0126] In one embodiment, the weight-average molecular weight of the additive may be in the range of 200 to 5,000 g / mol. When this range is satisfied, a balance between molecular mobility and bond retention force is secured, allowing for a stable dispersion state to be maintained within the resin matrix. Additionally, since the crack site can be rapidly sealed by the reversible movement of the additive, stable and rapid self-healing behavior can be exhibited in a temperature range of 20 to 80°C after a scratch.

[0127] The additive in the present invention may be directly incorporated into the resin, or it may be partially or entirely introduced in the form of a masterbatch. Here, a masterbatch refers to a formulation in which the additive is prepared in a composition form by dispersing it at a high concentration in a thermoplastic resin beforehand, and then a small amount is added during the preparation of the final composition to dilute it to a target concentration. This method is advantageous in that it ensures uniform dispersion of the additive and prevents metering errors or aggregation problems that may occur when adding trace amounts. In particular, stable mixing within the resin is possible even when the additive has adhesive or binding functional groups, thereby improving processability.

[0128] When only a portion of the above additive is introduced in the form of a masterbatch, the ratio may be in the range of 20 to 80 weight%, preferably 30 to 60 weight%, based on the total weight of the additive. When the above range is satisfied, the effect of improved dispersibility by the masterbatch and the cost reduction effect by direct mixing are balanced, thereby ensuring both the productivity of the entire process and the uniformity of self-restoring characteristics.

[0129] With reference to FIGS. 3 to 5, the processes of additive dispersion, hydrogen bond network formation, and self-restoration in a skin layer (20) according to an embodiment of the present invention will be explained.

[0130] First, when a scratch or crack occurs, hydrogen bonds around the cut surface are temporarily broken, forming microcracks; consequently, the continuity of the surface is reduced, leading to increased light scattering.

[0131] However, when the skin layer (20) prepared with the second resin composition according to the embodiment of the present invention is left at room temperature or subjected to low-temperature heat treatment, multi-point hydrogen bonds between the additive and the resin are reformed, causing the molecular chains to be rearranged, and self-healing occurs due to this reformed hydrogen bond network.

[0132] At this time, in the amorphous region (soft segment), reversible hydrogen bonds are rapidly restored, making the surface smooth, and the crystalline region (Crystallite, hard segment) acts as a fixed point of the network to stabilize the structure, thereby closing cracks and reducing light scattering.

[0134] Referring to FIG. 6, the method for manufacturing a multilayer interior material according to an embodiment of the present invention includes a raw material manufacturing step (S100), a first resin composition forming step (S200), a second resin composition forming step (S300), and a multilayer structure forming step (S400). The method for manufacturing the multilayer interior material is a method for manufacturing the multilayer interior material (1) according to the above-described embodiment. Accordingly, in this embodiment, the detailed description of the multilayer interior material (1) described in the above-described embodiment is omitted to avoid repetition.

[0135] The above raw material manufacturing step (S100) is a step of processing discarded seaweed drying racks to form recycled raw materials.

[0136] Referring to FIG. 7, the formation of the recycled raw material can be achieved by a method including a crushing and separation step (S10), a washing and sorting step (S20), a dehydration step (S30), and an extrusion step (S40).

[0137] The crushing and separation step (S10) is a step of crushing the discarded seaweed rack (100) into particles of a predetermined size and then separating them by each part and each material.

[0138] By the above crushing and separation step (S10), the gimbal (100) can be separated into HCPP resin and filler, ABS resin and PET fiber.

[0139] In one embodiment, the HCPP resin and filler may be included in an amount of 80 to 90 weight%, preferably 85 to 90 weight%, based on the total weight of the gimbal (100). The ABS resin may be included in an amount of 5 to 15 weight%, preferably 7 to 12 weight%, based on the total weight of the gimbal (100). The PET fiber may be included in an amount of 1 to 10 weight%, preferably 1 to 5 weight%, based on the total weight of the gimbal (100).

[0140] The washing and sorting step (S20) above is a step for removing foreign substances or debris from the particles that have passed through the crushing and separation step (S10), and can be performed by washing multiple times using water.

[0141] The above dehydration step (S30) is a step for removing residual water.

[0142] The extrusion step (S40) is a step of extruding the crushed particles to form them into pellets or flakes.

[0143] In this way, recycled raw materials derived from the discarded seaweed drying rack (100) can be formed.

[0144] The first resin composition forming step (S200) above is a step of forming a first resin composition containing the recycled raw material.

[0145] The above recycled raw material may include HCPP resin and filler derived from the first part (101) separated / selected by performing a processing process on the discarded seaweed rack (100).

[0146] The first resin composition may further include a first thermoplastic resin.

[0147] In one embodiment, the recycled raw material may be included in a range of 30 to 70 weight percent based on the total weight of the first resin composition. If the content of the recycled raw material is less than the above range, the effect of improving paintless color reproducibility and surface uniformity may be insufficient, and if it exceeds the above range, the variation in physical properties may increase, causing problems in securing uniform characteristics.

[0148] In one embodiment, the recycled raw material may be included in a range of 50 to 70 weight percent based on the total weight of the first resin composition.

[0149] The above second resin composition forming step (S300) is a step of forming a second resin composition having scratch concealment and self-healing performance.

[0150] The second resin composition may include a second thermoplastic resin and an additive.

[0151] The second thermoplastic resin above may include a urethane-based resin comprising a hard segment derived from diisocyanate and a soft segment derived from polyol.

[0152] The above additive may be a compound having a multi-point hydrogen bonding functional group. Specifically, the additive used in the present invention may be a compound comprising at least one hydrogen bond donor functional group and at least one hydrogen bond acceptor functional group.

[0153] The above additive may be in the range of 0.1 to 10 weight% or 0.1 to 5 weight% based on the total weight of the second resin composition. When the above range is satisfied, the additive is uniformly dispersed within the resin to provide sufficient bonding sites while suppressing phase separation or viscosity increase, thereby ensuring excellent molding stability and self-restoring effects simultaneously.

[0154] The above multilayer structure forming step (S400) is a step of forming a core layer containing the first resin composition and a skin layer containing the second resin composition.

[0155] The above multilayer structure formation step (S400) can be performed by a multilayer molding process.

[0156] In one embodiment, the multilayer structure forming step (S400) may be performed by a method selected from the group consisting of multilayer injection molding, multilayer extrusion molding, lamination, and combinations thereof.

[0158] Accordingly, the multilayer interior material having unpainted color reproducibility and self-restoring properties and the method for manufacturing the same according to an embodiment of the present invention provide a multilayer interior material having unpainted color reproducibility and self-restoring properties and a method for manufacturing the same that can increase the purity of the seaweed sheet used as a raw material for the core layer, reduce variations in physical properties, foreign substances, and odors to improve surface uniformity, secure rigidity and heat resistance, and configure a background tone similar to the color of the skin layer. Furthermore, according to the multilayer interior material having unpainted color reproducibility and self-restoring properties and the method for manufacturing the same according to an embodiment of the present invention, scratches can be visually concealed and efficiently self-restored so that a visual return to the color of the skin layer can be achieved when a scratch occurs. In addition, according to the multilayer interior material having unpainted color reproducibility and self-restoring properties and the method for manufacturing the same according to an embodiment of the present invention, it can be efficiently manufactured by a conventional multilayer molding process without separate additional processes or increased costs, and the design freedom of structure and rigidity can be increased.

[0160] As described above, the present invention has been explained with reference to the embodiments illustrated in the drawings, but this is merely illustrative, and it should be understood that various modifications and equivalent alternative embodiments are possible based on the ordinary knowledge of the art to which the art belongs. Accordingly, the true technical scope of protection of the present invention is defined by the claims described below and should be determined based on the specific details of the invention described above. Industrial applicability

[0162] The present invention relates to a multilayer interior material having paintless color reproducibility and self-restoring properties, and a method for manufacturing the same, and is applicable to industrial fields related to automotive interior materials.

[0163] No content Explanation of the symbols

[0164] 1: Multilayer interior material 10: Core layer 20: Skin layer 100: Seaweed sheet 101: Part 1 102: Part 2 103: Part 3

Claims

Claim 1 A multilayer interior material comprising: a core layer comprising a first resin composition containing recycled raw materials derived from a seaweed drying rack; and a skin layer comprising a second resin composition having scratch concealment and self-restoration performance; wherein the second resin composition comprises a second thermoplastic resin and an additive, the second thermoplastic resin comprises a urethane resin comprising a hard segment derived from a diisocyanate and a soft segment derived from a polyol, and the additive comprises at least one hydrogen bond donor functional group and at least one receiving functional group. Claim 2 A multilayer interior material according to claim 1, characterized in that the recycled raw material comprises HCPP (High Crystalline Polypropylene) resin and a filler. Claim 3 A multilayer interior material according to claim 2, wherein the filler is selected from the group consisting of talc, carbon black, calcium oxide, magnesium oxide, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium carbonate, magnesium carbonate, calcium silicate, magnesium silicate, calcium sulfate, barium sulfate, calcium sulfite, mica, clay, dolomite, glass beads, glass fibers, and combinations thereof. Claim 4 A multilayer interior material according to claim 1, characterized in that the recycled raw material is included in a range of 30 to 70 weight percent based on the total weight of the core layer. Claim 5 A multilayer interior material according to claim 1, wherein the first resin composition comprises a recycled raw material derived from the above-mentioned seaweed drying rack and a first thermoplastic resin. Claim 6 A multilayer interior material according to claim 5, wherein the first thermoplastic resin is selected from the group consisting of PP (Polypropylene), PE (Polyethylene), ABS (Acrylonitrile Butadiene Styrene), PC (Polycarbonate), PA (Polyamide), PET (Poly(ethylene terephthalate)), PVC (Polyvinyl chloride), TPO (Thermoplastic olefin), and combinations thereof. Claim 7 A multilayer interior material according to claim 1, wherein the core layer has a color that matches the color of the skin layer to satisfy a preset ΔE value. Claim 8 A multilayer interior material according to claim 7, characterized in that the color of the core layer is controlled using the color of recycled raw material derived from the above-mentioned seaweed drying rack. Claim 9 delete Claim 10 A multilayer interior material according to claim 1, wherein the hydrogen bond donating functional group comprises at least one selected from the group consisting of an amino group (-NH2), an imino group (-NH-), and a hydroxyl group (-OH), and the hydrogen bond accepting functional group comprises at least one selected from the group consisting of a carbonyl group (C=O), a thiocarbonyl group (C=S), an ether group (-O-), an amide group (-CONH-), and an isocyanurate group (-NCO-). Claim 11 A multilayer interior material according to claim 1, wherein the diisocyanate comprises at least one selected from the group consisting of aliphatic, alicyclic, aliphatic-alicyclic, and aromatic diisocyanate compounds, and the polyol comprises at least one selected from the group consisting of polyether polyol, polyester polyol, and polycarbonate polyol. Claim 12 A multilayer interior material according to claim 1, wherein the diisocyanate comprises at least one selected from the group consisting of methylenebis(phenylisocyanate) (MDI), hexamethylene diisocyanate (HDI), and isophorone diisocyanate (IPDI), and the polyol comprises at least one selected from the group consisting of polytetramethylene glycol (PTMG), polycaprolactone diol (PCL), and polycarbonate diol (PCD). Claim 13 A multilayer interior material according to claim 1, characterized in that the weight ratio of the hard segment to the soft segment in the second thermoplastic resin is in the range of 30:70 to 60:

40. Claim 14 A multilayer interior material according to claim 1, characterized in that the additive is included in an amount of 0.1 to 10 weight% based on the total weight of the second resin composition. Claim 15 A multilayer interior material according to claim 1, characterized in that the additive comprises at least one selected from the group consisting of urea-based compounds, carbamate-based compounds, isocyanurate-based compounds, and amide-based compounds. Claim 16 A multilayer interior material according to claim 15, characterized in that the urea-based compound comprises at least one selected from the group consisting of thiourea, 1,3-bis(3-aminopropyl)urea, N,N'-diphenylurea, and bis(4-aminophenyl)urea. Claim 17 A multilayer interior material according to claim 1, characterized in that the additive has a weight-average molecular weight in the range of 200 to 5,000 g / mol. Claim 18 A multilayer interior material according to claim 1, characterized in that the skin layer can exhibit self-restoring properties in a temperature range of 20 to 80°C. Claim 19 A method for manufacturing a multilayer interior material according to any one of claims 1 to 8 or claims 10 to 18, comprising: a raw material manufacturing step of processing discarded seaweed drying racks to form recycled raw materials; a first resin composition forming step of forming a first resin composition comprising said recycled raw materials; a second resin composition forming step of forming a second resin composition having scratch concealment and self-restoration performance; and a multilayer structure forming step of forming a core layer comprising said first resin composition and a skin layer comprising said second resin composition by a multilayer molding process; wherein the second resin composition comprises a second thermoplastic resin and an additive, said second thermoplastic resin comprises a urethane resin comprising a hard segment derived from diisocyanate and a soft segment derived from polyol, and said additive comprises at least one hydrogen bond donor functional group and at least one receiving functional group. Claim 20 A method for manufacturing a multilayer interior material according to claim 19, wherein the raw material manufacturing step is carried out by a method comprising a crushing and separation step; a washing and screening step; a dehydration step; and an extrusion step. Claim 21 A method for manufacturing a multilayer interior material according to claim 19, wherein the step of forming the multilayer structure is performed by a method selected from the group consisting of multilayer injection molding, multilayer extrusion molding, lamination, and combinations thereof.

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