Recycled raw material-based biodegradable adhesive obtained from waste plastic and manufacturing method therefor

Abstract

The present invention relates to a biodegradable adhesive, a manufacturing method therefor, and an adhesive sheet comprising same, the biodegradable adhesive comprising: epoxidized soybean oil; and two or more kinds of aliphatic dicarboxylic acid compounds obtained by oxidizing waste plastic, wherein the biodegradable adhesive not only exhibits improved adhesive properties and high biodegradability, but also has excellent eco-friendliness due to the preparation thereof using raw materials obtained by recycling waste.

Description

Biodegradable adhesive based on recycled raw materials obtained from waste plastic and method for producing the same

[0001] The present invention relates to a biodegradable adhesive based on a recycled raw material obtained from waste plastic and a method for producing the same.

[0002] Adhesives utilize the principle of easily bonding to surfaces even under low pressure, finding wide application in a wide range of fields, including electronics, medicine, and automobiles. However, most commercially available adhesives are composed of petroleum-based chemicals and are applied to synthetic resin substrates, making recycling and waste disposal difficult. To overcome this, eco-friendly water-soluble adhesives or biodegradable adhesives or adhesive tapes using biomass-derived adhesive resins on eco-friendly substrates like paper have been developed. However, these products face challenges in achieving the desired adhesive properties.

[0003] Meanwhile, global plastic production and consumption continue to increase. However, the processing and recycling efficiency of waste plastic is extremely low, resulting in severe environmental problems such as plastic waste-related pollution and climate change due to carbon emissions. Research has been conducted to recycle waste plastic, but controlling the composition and properties of the recycled raw materials obtained through waste plastic recycling is extremely difficult, limiting their effectiveness.

[0004] Accordingly, there is a need to develop an adhesive that is not only environmentally friendly by manufacturing the adhesive using recycled raw materials obtained from waste plastic, but also has excellent adhesive properties and biodegradability by controlling the composition of the recycled raw materials obtained from waste plastic.

[0005] The purpose of the present invention is to solve the problems of the above-mentioned prior art, and to provide a biodegradable adhesive having excellent adhesive properties and biodegradability and a method for producing the same by controlling the composition of raw materials obtained from waste plastic.

[0006] Another object of the present invention is to provide a biodegradable adhesive having an environmentally friendly advantage through recycling of waste materials and a method for producing the same.

[0007] The biodegradable adhesive according to the present invention comprises epoxidized soybean oil; and two or more kinds of aliphatic dicarboxylic acid compounds obtained by oxidizing waste plastic.

[0008] In one example, the aliphatic dicarboxylic acid compounds may include aliphatic dicarboxylic acid compounds having 2 to 10 carbon atoms.

[0009] In one example, the aliphatic dicarboxylic acid compounds may contain 5 wt% or less of an aliphatic dicarboxylic acid compound having 3 or fewer carbon atoms.

[0010] In one example, the aliphatic dicarboxylic acid compounds may contain 50 to 100 wt% of aliphatic dicarboxylic acid compounds having 4 or more carbon atoms.

[0011] In one example, the average carbon number of the aliphatic dicarboxylic acid compounds may be 4 to 10.

[0012] In one example, the aliphatic dicarboxylic acid compounds may be a mixture of two or more selected from the group consisting of oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid.

[0013] In one example, the epoxidized soybean oil may have 10 to 30% of the double bonds of unsaturated fatty acids replaced with epoxide.

[0014] In one example, the molar ratio of the aliphatic dicarboxylic acid compounds and the epoxide may be 1:1 to 5.

[0015] In one example, the aliphatic dicarboxylic acid compounds may be obtained by oxidizing waste plastic by immersing it in an acidic solution.

[0016] In one example, the epoxidized soybean oil and aliphatic dicarboxylic acid compounds may be cross-linked.

[0017] In one example, the biodegradable adhesive may further include a tackifier.

[0018] In one example, the tackifier may comprise a natural polymer.

[0019] In one example, the tackifier may be included in an amount of 20 to 60 wt% relative to the total weight of the biodegradable adhesive.

[0020] The present invention includes a biodegradable adhesive sheet comprising the biodegradable adhesive described above.

[0021] A biodegradable adhesive sheet according to the present invention comprises a substrate; and an adhesive layer positioned on the substrate and containing the biodegradable adhesive described above.

[0022] In one example, the thickness of the adhesive layer may be 50 to 500 μm.

[0023] In one example, the substrate may include a polymer film.

[0024] The present invention includes a method for producing the biodegradable adhesive described above.

[0025] Another method for manufacturing a biodegradable adhesive according to the present invention comprises the steps of (S1) immersing waste plastic in an acidic solution to oxidize it; (S2) separating two or more types of aliphatic dicarboxylic acid compounds from a solution containing the oxidized waste plastic; (S3) mixing the aliphatic dicarboxylic acid compounds with epoxidized soybean oil to polymerize them; and (S4) curing the polymer.

[0026] In one example, in the step (S3), a tackifier may be further added during mixing.

[0027] In one example, the two or more types of aliphatic dicarboxylic acid compounds obtained in the step (S2) may include aliphatic dicarboxylic acid compounds having 2 to 10 carbon atoms.

[0028] In one example, the aliphatic dicarboxylic acid compounds obtained in the step (S2) may contain 5 wt% or less of an aliphatic dicarboxylic acid compound having 3 or fewer carbon atoms, and 50 to 100 wt% of an aliphatic dicarboxylic acid compound having 4 or more carbon atoms.

[0029] The biodegradable adhesive and its manufacturing method according to the present invention can simultaneously achieve excellent adhesive properties and biodegradability by controlling the composition of raw materials obtained from waste plastic.

[0030] Additionally, it has environmentally friendly advantages as it is made by recycling waste plastic to produce biodegradable adhesive.

[0031] Figure 1 is a graph analyzing the composition of two or more types of dicarboxylic acid compounds obtained from waste plastics according to Examples 1 to 6.

[0032] Figure 2 is a schematic diagram illustrating a method for measuring the peel strength of a biodegradable adhesive sheet according to one embodiment.

[0033] Figure 3 is a graph showing the measurement of biochemical oxygen demand of biodegradable adhesives according to Example 2 and Comparative Example 1.

[0034] Figure 4 is a graph measuring the biodegradability of biodegradable adhesives according to Example 2 and Comparative Example 1 compared to cellulose.

[0035] The present invention provides a detailed description of a biodegradable adhesive based on recycled raw materials obtained from waste plastic and a method for manufacturing the same. The terminology used in this specification has been selected from widely used terms, taking into account the functions of the present invention. However, this may vary depending on the intentions of engineers working in the relevant fields, precedents, the emergence of new technologies, etc. Unless otherwise defined, the technical and scientific terms used shall have the meaning commonly understood by those skilled in the art to which this invention pertains.

[0036] In this specification and the appended claims, the terms “include” or “have” mean that a feature or component described in the specification is present, and unless specifically limited, does not preclude the possibility that one or more other features or components may be added.

[0037] In this specification and the appended claims, the terms first, second, etc. are not used in a limiting sense but are used for the purpose of distinguishing one component from another.

[0038] As used herein and in the appended claims, the singular expression "singular" includes the plural expression unless the context clearly dictates otherwise. Furthermore, the plural expression "singular" includes the singular expression unless the context clearly dictates otherwise.

[0039] Additionally, the numerical ranges used herein include lower and upper limits and all values ​​within that range, increments logically derived from the shape and width of the defined range, all doubly defined values, and all possible combinations of upper and lower limits of numerical ranges defined in different shapes. Unless otherwise specifically defined in the specification of the present invention, values ​​outside the numerical range that may arise due to experimental error or rounding of values ​​are also included in the defined numerical range.

[0040] The term "about" or the like used in this specification and the appended claims is used to encompass the tolerance when an tolerance exists.

[0041] Adhesives adhere easily to surfaces even under low pressure, making them widely useful in fields such as electronics, medicine, and automotive applications. However, most commercially available adhesives are made of petroleum-based chemicals and are applied to synthetic resin substrates, making recycling and waste disposal difficult. To overcome this, eco-friendly water-soluble adhesives or biodegradable adhesives or adhesive tapes using biomass-derived adhesive resins have been developed. However, these biodegradable adhesives suffer from inferior adhesive properties compared to conventional adhesives.

[0042] Meanwhile, global plastic production and consumption continue to increase. However, the processing and recycling efficiency of waste plastic is extremely low, resulting in severe environmental problems such as plastic waste-related pollution and climate change due to carbon emissions. Research has been conducted to recycle waste plastic, but controlling the composition and properties of the recycled raw materials obtained through waste plastic recycling is extremely difficult, limiting their effectiveness.

[0043] Accordingly, after in-depth research, the applicant has developed a biodegradable adhesive that not only has excellent eco-friendliness but also has improved adhesive properties and biodegradability by controlling the composition of raw materials obtained by recycling waste plastic.

[0044] The biodegradable adhesive of the present invention comprises epoxidized soybean oil; and two or more kinds of aliphatic dicarboxylic acid compounds obtained by oxidizing waste plastic.

[0045] The adhesive of the present invention not only has biodegradable properties, but also has high environmental friendliness by reducing the amount of waste plastic discharged, since the adhesive is manufactured using dicarboxylic acid compounds obtained from waste plastic.

[0046] In addition, by controlling the composition of two or more types of aliphatic dicarboxylic acid compounds manufactured by oxidizing waste plastic, an eco-friendly biodegradable adhesive with excellent adhesive properties can be realized.

[0047] Specifically, the biodegradable adhesive has improved adhesive strength and cohesiveness, resulting in no residue remaining on the substrate when removed. Furthermore, its excellent flexibility and anchoring strength enable it to adhere with high adhesive strength even to curved and uneven substrates.

[0048] The two or more types of aliphatic dicarboxylic acid compounds obtained by oxidizing the above waste plastic may include aliphatic dicarboxylic acid compounds having 2 to 20, 2 to 15, or 2 to 10 carbon atoms. Here, the carbon number refers to the total number of carbon atoms including carbon atoms of the carboxyl group in the dicarboxylic acid compound.

[0049] More specifically, the two or more kinds of aliphatic dicarboxylic acid compounds include aliphatic saturated dicarboxylic acids, and more specifically, may include two or more selected from the group consisting of oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid. A biodegradable adhesive comprising aliphatic dicarboxylic acid compounds having a carbon number in the above range and epoxidized soybean oil may have improved adhesive properties and thus high adhesive properties.

[0050] In one example, the aliphatic dicarboxylic acid compounds may contain 5 wt% or less, 3 wt% or less, or 1 wt% or less of an aliphatic dicarboxylic acid compound having 3 or fewer carbon atoms, specifically oxalic acid and malonic acid, and may contain, but is not limited to, 0.01 wt% or more.

[0051] Additionally, the aliphatic dicarboxylic acid compounds may contain 50 to 100 wt%, 60 to 98 wt%, or 70 to 97 wt% of aliphatic dicarboxylic acid compounds having 4 or more carbon atoms. Specifically, the aliphatic dicarboxylic acid compounds having 4 to 20, 4 to 15, 4 to 10, or 4 to 7 carbon atoms may contain 50 to 100 wt%, 60 to 98 wt%, or 70 to 97 wt%.

[0052] A biodegradable adhesive comprising dicarboxylic acid compounds of the above composition can have improved adhesive properties due to excellent viscoelastic properties, and at the same time, excellent biodegradability.

[0053] In one specific example, aliphatic dicarboxylic acid compounds having the above composition can be obtained by oxidizing waste plastic by immersing it in an acidic solution. By oxidizing waste plastic by immersing it in an acidic solution, the composition of aliphatic dicarboxylic acids can be adjusted within the above range.

[0054] The number average molecular weight of the above aliphatic dicarboxylic acid compounds may be 80 to 2000, 90 to 1000, or 100 to 500. In addition, the average carbon number of the above aliphatic dicarboxylic acid compounds may be 4 to 10, 4.2 to 8, or 4.4 to 6. A biodegradable adhesive comprising aliphatic dicarboxylic acid compounds having the above molecular weight and average carbon number ranges can improve adhesive properties and biodegradability.

[0055] The aliphatic dicarboxylic acid compounds obtained from the above waste plastic and epoxidized soybean oil can form crosslinks. Crosslinking can be formed through an epoxy ring-opening reaction between the hydroxyl groups (-OH) present at the terminals of the dicarboxylic acid compounds and the epoxide of the epoxidized soybean oil, thereby improving the cohesiveness of the adhesive.

[0056] In one example, the molar ratio of the aliphatic dicarboxylic acid compound: epoxide may be 1:1 to 5, 1:1.3 to 4, or 1:1.5 to 3. In the above range, the effect of improving cohesion through cross-linking between the aliphatic dicarboxylic acid compound and the epoxide may be enhanced.

[0057] Epoxidized soybean oil is a plant-derived ingredient that not only has excellent biodegradability and economic advantages, but can also improve the flexibility and transparency of pressure-sensitive adhesives. The epoxidized soybean oil may have 10 to 30%, 13 to 25%, or 15 to 20% of the double bonds of unsaturated fatty acids substituted with epoxides. By substituting the double bonds of unsaturated fatty acids with epoxides within the above ranges, the crosslinking density of the pressure-sensitive adhesive is controlled, thereby improving the flexibility and cohesiveness of the pressure-sensitive adhesive.

[0058] For example, the biodegradable adhesive may further include a tackifier to enhance adhesive strength. The tackifier may include a natural polymer with biodegradable properties, and more specifically, a rosin-based tackifier may be included considering compatibility with epoxidized soybean oil and aliphatic dicarboxylic acid compounds. However, the present invention is not limited to the specific type of the adhesive.

[0059] In one example, the tackifier may be included in an amount of 20 to 60 wt%, 25 to 55 wt%, or 30 to 50 wt% relative to the total weight of the biodegradable adhesive. By including the tackifier in the above range, the adhesive strength can be improved while maintaining good viscosity.

[0060] The present invention includes an adhesive sheet comprising the biodegradable adhesive described above and a method for producing the biodegradable adhesive described above. In describing the adhesive sheet and the method for producing the biodegradable adhesive, the materials, structures, shapes, sizes, etc. of the epoxidized soybean oil and dicarboxylic acid compounds contained in the biodegradable adhesive are identical or similar to those of the biodegradable adhesive described above, and therefore, all of the contents described above are included.

[0061] The adhesive sheet of the present invention comprises a substrate; and an adhesive layer positioned on the substrate and including the biodegradable adhesive described above.

[0062] As described above, when the biodegradable adhesive of the present invention is incorporated, adhesive properties can be enhanced with excellent cohesiveness, transparency, flexibility, and adhesive strength. Furthermore, it can exhibit excellent environmental friendliness due to biodegradability and waste recycling. Therefore, it has the advantage of being widely applicable to a wide range of fields, including flexible displays, electronic components, medical devices, and automobiles.

[0063] The biodegradable adhesive of the present invention can be applied to a substrate at a uniform thickness and effectively adhere to an adherend. In one specific example, the thickness of the adhesive layer may be 50 to 500 μm, 70 to 300 μm, or 90 to 200 μm.

[0064] In one example, the substrate may be selected from various materials appropriately by a person skilled in the art depending on the field in which the biodegradable adhesive is used, and may include, for example, a metal foil, a non-woven fabric, glass, paper, rayon, cotton, or a fabric such as polyethylene terephthalate (PET), polyvinyl chloride (PVC), polyvinyl alcohol (PVA), polyimide (PI), polybutylene terephthalate, oriented polypropylene (OPP), polypropylene (PP), polycarbonate (PC), and polyethylene (PE) and one or more polymer films selected from the group consisting of polyethylene terephthalate (PET), polyvinyl chloride (PVC), polyvinyl alcohol (PVA), polyimide (PI), polybutylene terephthalate, oriented polypropylene (OPP), polypropylene (PP), polycarbonate (PC), and polyethylene (PE).

[0065] The method for manufacturing a biodegradable adhesive of the present invention comprises the steps of (S1) immersing waste plastic in an acidic solution to oxidize it; (S2) separating two or more types of aliphatic dicarboxylic acid compounds from a solution containing the oxidized waste plastic; (S3) mixing the aliphatic dicarboxylic acid compounds with epoxidized soybean oil to polymerize them; and (S4) curing the polymer.

[0066] Dicarboxylic acid compounds having the above-described composition can be formed through the step (S1) of oxidizing waste plastic by immersing it in an acidic solution. In particular, as described above, by producing a large amount of low-molecular-weight dicarboxylic acid compounds having carbon atoms of C4 to C7, the viscoelastic properties of the biodegradable adhesive ultimately produced can be realized.

[0067] The acidic solution of the above step (S1) may include an inorganic acid. Specifically, the inorganic acid may include one or more selected from the group consisting of hydrochloric acid (HCl), nitric acid (HNO3), phosphoric acid (H3PO4), sulfuric acid (H2SO4), boric acid (H3BO3), hydrofluoric acid (HF), hydrogen bromide (HBr), and carbonic acid (H2CO3), but the present invention is not limited by the specific type of the inorganic acid.

[0068] In order to produce dicarboxylic acid compounds having the above composition from waste plastic, step (S1) can be performed under conditions of a temperature of 70 to 300°C, 100 to 250°C, or 150 to 200°C and a pressure of 10 to 120 bar, 20 to 100 bar, or 30 to 80 bar, and the waste plastic can be oxidized under the above conditions for 0.1 to 5 hours, 0.3 to 4 hours, or 0.5 to 3 hours.

[0069] (S2) Step can separate two or more types of aliphatic dicarboxylic acid compounds from a solution containing oxidized waste plastic, and remove high molecular weight dicarboxylic acid compounds having 10 or more carbon atoms, salts, and byproducts contained in the solution to obtain high-purity low molecular weight aliphatic dicarboxylic acid compounds.

[0070] (S2) The step may adopt a separation process commonly used in the industry, and may be performed specifically through a distillation process, more specifically through a reduced pressure distillation process.

[0071] Step (S3) is a process of mixing and polymerizing aliphatic dicarboxylic acid compounds obtained from waste plastic through steps (S1) and (S2) with epoxidized soybean oil, and the viscosity of the polymer prepared through step (S3) may be 3000 to 50000 cP, 4000 to 40000 cP, or 5000 to 20000 cP. In the above viscosity range, the coating workability is improved, so that the polymer can be uniformly applied to a desired thickness, and the polymer can maintain its shape without flowing during application.

[0072] The above steps (S1) and (S3) can be performed using a microwave. By shortening the process time using a microwave and thus reducing the time of exposure to heat, the stability of the adhesive can be improved and the process efficiency can be increased.

[0073] In the above step (S3), a tackifier may be further added when mixing aliphatic dicarboxylic acid compounds and epoxidized soybean oil. It is preferable to use the tackifier in a liquid form to prevent the mixed solution from gelling and the viscosity of the polymer from excessively increasing beyond the above range.

[0074] Step (S4) is a step for producing an adhesive by curing a polymer, which can form cross-linking between epoxidized soybean oil and an aliphatic dicarboxylic acid compound to improve the cohesiveness of the adhesive. In one specific example, curing can be performed by heat curing at 50 to 300°C, 100 to 250°C, or 150 to 200°C for 0.5 to 10 hours, 0.8 to 8 hours, or 1 to 6 hours.

[0075] For example, a polymer may be applied to a substrate and then cured to simultaneously produce an adhesive and an adhesive sheet. Application may be accomplished using any known application method, and examples thereof include spin coating, roll coating, dip coating, bar coating, gravure coating, and spray coating.

[0076] Hereinafter, the present invention will be described in more detail through examples.

[0077] (Example 1)

[0078] 0.375 g of commercial HDPE (High Density Polyethylene) cut into strips measuring 5 cm x 5 mm was added to 15 ml of a nitric acid solution having a concentration of 0.25 g / ml, and oxidized in a microwave reactor (Anton-Paar, Multiwave pro) at 180°C and 60 bar for 30 minutes. Subsequently, reduced pressure distillation was repeated twice to obtain powders of aliphatic dicarboxylic acid compounds.

[0079] The above dicarboxylic acid compounds and epoxidized soybean oil containing 17.6% of epoxy groups were placed in a Teflon vessel, and then 16.32 g of a liquid rosin-based tackifier was added and mixed. At this time, the liquid tackifier was prepared by stirring acetone: solid rosin-based tackifier at a weight ratio of 4:1 for 8 hours or more, and was placed in the Teflon vessel.

[0080] A Teflon vessel containing the above-described mixed solution was placed in a microwave heated to 55°C, polymerized for 7 minutes at an output of 1000 W, and cooled to 70°C to produce a polymer. Thereafter, the polymer was applied to one side of a PET film at a coating speed of 25 mm / sec to a thickness of 100 μm. During the polymer application, the other side of the PET film was heated to 60°C. The PET film coated with the polymer was placed in a thermal circulation oven and cured at 150°C for 6 hours to produce a biodegradable adhesive and an adhesive sheet including the same.

[0081] (Example 2)

[0082] A biodegradable adhesive and an adhesive sheet including the same were manufactured in the same manner as in Example 1, except that HDPE was immersed in a nitric acid solution and oxidized for 1 hour.

[0083] (Example 3)

[0084] A biodegradable adhesive and an adhesive sheet including the same were manufactured in the same manner as in Example 1, except that HDPE was immersed in a nitric acid solution having a concentration of 0.15 g / ml and oxidized for 1 hour.

[0085] (Example 4)

[0086] A biodegradable adhesive and an adhesive sheet containing the same were prepared in the same manner as in Example 3, except that HDPE was oxidized for 2 hours.

[0087] (Example 5)

[0088] A biodegradable adhesive and an adhesive sheet including the same were manufactured in the same manner as in Example 1, except that a solution containing 0.375 g of LDPE (Low Density Polyethylene) added to 15 ml of a 0.25 g / ml nitric acid solution was oxidized at 180°C and 60 bar for 1 hour.

[0089] (Example 6)

[0090] A biodegradable adhesive and an adhesive sheet including the same were manufactured in the same manner as in Example 5, except that LDPE was oxidized for 2 hours.

[0091] (Example 7)

[0092] A biodegradable adhesive and an adhesive sheet including the same were manufactured in the same manner as in Example 2, except that curing was performed in a heat circulation oven at 170°C for 3 hours during curing.

[0093] (Example 8)

[0094] A biodegradable adhesive and an adhesive sheet including the same were manufactured in the same manner as in Example 2, except that curing was performed in a heat circulation oven at 190°C for 2 hours during curing.

[0095] (Comparative Example 1)

[0096] A commercial double-sided adhesive tape containing an acrylic adhesive (3M scotch, paper double-sided tape) was used.

[0097] (Experimental Example 1) Composition analysis of dicarboxylic acid compounds

[0098] When manufacturing a biodegradable adhesive using the methods of Examples 1 to 6, the powders of two or more types of dicarboxylic acid compounds obtained from waste plastic were analyzed for composition using high-performance liquid chromatography, and the results are shown in Table 1 and Figure 1 below.

[0099] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Waste plastic HDPE LDPE Nitric acid concentration (g / ml) 0.25 0.15 0.25 Oxidation time 30 minutes 1 hour 1 hour 2 hours 1 hour 2 hours Acetic acid (C2) 85.57% - 83.83% 23.59% 48.67% 77.57% Propionic acid (C3) - 0.57% 9.75% 2.99% 19.81% - Malonic acid (C3) - 1.33% 0.79% --- Succinic acid (C4) - 63.26% 0.25% 9. 97% 4.25% 22.43% Glutaric acid (C5) 14.43% 20.54% 2.34% 18.01% 10.79% Adipic acid (C6) 13.18% 31.24% 16.48% Pimelic acid (C7) 1.12% 3.05% 14.2% Total 100% 100% 100% 100% 100%

[0100] Referring to Fig. 1 and Table 1, in the case of Example 2, acetic acid and propionic acid, which are monocarboxylic acids, were contained in very small amounts of 0.57%, whereas the contents of succinic acid, glutaric acid, adipic acid, and pimelic acid of C4 or higher were very high at 96.98%. In Example 4, the content of dicarboxylic acid compounds of C4 or higher was 73.42%, and dicarboxylic acid compounds having 4 or more carbon atoms were dominantly contained. Therefore, the biodegradable adhesives manufactured by the methods of Examples 2 and 4 were able to implement viscoelastic properties suitable for adhesives.

[0101] On the other hand, in the case of Example 1, it can be confirmed that it contains a large amount of acetic acid, which is a monocarboxylic acid, at 85.57%, and a small amount of dicarboxylic acid at 14.43%. Examples 3 and 6 also contained acetic acid dominantly like Example 1, and the content of dicarboxylic acid was very low at 30% or less. In Example 5, the content of dicarboxylic acid compounds of C4 or higher was 31.52%, which was a slight increase compared to Examples 1, 3, and 6, but the content of acetic acid and propionic acid was 68.48%, which was a higher content of monocarboxylic acid compounds than dicarboxylic acid compounds. Therefore, the biodegradable adhesives manufactured by the methods of Examples 1, 3, 5, and 6 had a problem in that it was difficult to implement viscoelastic properties suitable for the adhesive.

[0102] (Experimental Example 2) Adhesive property evaluation

[0103] The adhesive sheets manufactured by the methods of Examples 1 to 8 were cut to a width of 25 mm. The adhesive sheets were attached so that the adhesive surface of the adhesive sheets was in contact with a stainless steel (SUS) plate, and the stainless steel surface was rolled with a 2 kg hand roller to bond the stainless steel plate to the adhesive sheets. The rolling was repeated 5 times, and the adhesive sheets were then aged at room temperature for 3 hours. Thereafter, the 180° peel strength of the adhesive sheets was measured at a speed of 10 cm / min using a universal testing machine (UTM), as shown in Fig. 2. The measurement results are shown in Table 2 below.

[0104] Peel strength (N / 25mm) Destruction form Coated thickness (㎛) Example 12.71-110.1 Example 219.80 Interface 129.0 Example 33.53-104.3 Example 417.45 Interface 124.2 Example 57.16-107.6 Example 65.94-107.9 Example 716.59-129 Example 819.80 Interface 108.7

[0105] As shown in Table 2, the biodegradable adhesives of Examples 2 and 4 contained dicarboxylic acid compounds obtained from waste plastics predominantly containing succinic acid, glutaric acid, adipic acid, and pimelic acid having 4 or more carbon atoms, and thus had excellent rheological properties. As a result, the peel strength, i.e., the adhesive strength, was measured to be high at 19.8 N / 25mm and 17.45 N / 25mm, respectively. In addition, looking at the failure patterns, the adhesives of Examples 2 and 4 experienced interfacial failure, where failure occurred at the interface between the adhesive and the adherend (stainless steel), and no residue was left on the adherend. Examples 7 and 8, which used dicarboxylic acid compounds having the same composition as Example 2, also exhibited peel strengths of 16.59 N / 25mm and 19.80 N / 25mm, respectively, and exhibited excellent adhesive properties due to interfacial failure.

[0106] However, in the case of the adhesive sheets of Examples 1, 3, 5, and 6, in which the dicarboxylic acid compounds contained a small amount of dicarboxylic acid compounds having a thickness of C4 or greater, the peel strengths were 2.71 N / 25 mm, 3.53 N / 25 mm, 7.16 N / 25 mm, and 5.94 N / 25 mm, respectively, which were significantly lower than those of Examples 2, 4, 7, and 8. In addition, since the viscoelastic properties were very low, no interface destruction occurred upon destruction, and residue remained on the stainless steel even after the adhesive sheet was peeled from the stainless steel.

[0107] (Experimental Example 3) Biodegradability Evaluation

[0108] The biodegradability of the biodegradable adhesives according to Example 2 and Comparative Example 1 was evaluated using a BOD measurement system (WTW, OxiTop®). To simulate biodegradability in a natural environment, the oxygen consumption in a closed respiratory system was measured for 60 days according to the ISO 14851 standard, and the biodegradability was compared with that of cellulose, a standard material. The measurement results are shown in Figures 3 and 4 and Table 3 below, and the biodegradability was calculated using the following Equation 1.

[0109] Biochemical oxygen demand (mg / g for 60 days) Biodegradability (%) compared to cellulose Cellulose powder 50 mg 73.45 mg / g - Example 2 20 mg 16.2 mg / g 25.04 % Comparative example 1 20 mg 4.1 mg / g 6.82 %

[0110] [Formula 1]

[0111]

[0112] Referring to FIGS. 3, 4, and Table 4, in the case of the commercial adhesive tape containing the acrylic adhesive of Comparative Example 1, the biochemical oxygen demand was 4.1%, and the biodegradability was also very low at 6.82% compared to cellulose. However, in the case of Example 2, the biochemical oxygen demand was 16.2%, and the biodegradability was high at 25.04% compared to cellulose, indicating excellent biodegradability compared to the commercial adhesive tape containing the acrylic adhesive, and thus, it can be seen that the eco-friendliness was improved.

[0113] As described above, the present invention has been described with specific details and limited examples and drawings, but these are provided only to help a more general understanding of the present invention, and the present invention is not limited to the above examples, and those skilled in the art to which the present invention pertains can make various modifications and variations based on this description.

[0114] Therefore, the idea of ​​the present invention should not be limited to the described embodiments, and all things that are equivalent or equivalent to the claims described below as well as the claims are considered to fall within the scope of the idea of ​​the present invention.

Claims

1. Epoxidized soybean oil; and A biodegradable adhesive comprising two or more kinds of aliphatic dicarboxylic acid compounds obtained by oxidizing waste plastic.

2. In paragraph 1, A biodegradable adhesive comprising the above aliphatic dicarboxylic acid compounds having 2 to 10 carbon atoms.

3. In paragraph 1, A biodegradable adhesive, wherein the above aliphatic dicarboxylic acid compounds contain 5 wt% or less of aliphatic dicarboxylic acid compounds having 3 or fewer carbon atoms.

4. In paragraph 1, A biodegradable adhesive, wherein the above aliphatic dicarboxylic acid compounds contain 50 to 100 wt% of aliphatic dicarboxylic acid compounds having 4 or more carbon atoms.

5. In paragraph 1, A biodegradable adhesive, wherein the average carbon number of the above aliphatic dicarboxylic acid compounds is 4 to 10.

6. In paragraph 1, A biodegradable adhesive, wherein the above aliphatic dicarboxylic acid compounds are a mixture of two or more selected from the group consisting of oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid and sebacic acid.

7. In paragraph 1, The above epoxidized soybean oil is a biodegradable adhesive in which 10 to 30% of the double bonds of unsaturated fatty acids are replaced with epoxide.

8. In paragraph 1, A biodegradable adhesive, wherein the molar ratio of the above-mentioned aliphatic dicarboxylic acid compounds and epoxide is 1:1 to 5.

9. In paragraph 1, The above aliphatic dicarboxylic acid compounds are biodegradable adhesives obtained by oxidizing waste plastic by immersing it in an acidic solution.

10. In paragraph 1, A biodegradable adhesive wherein the epoxidized soybean oil and the aliphatic dicarboxylic acid compounds are cross-linked.

11. In paragraph 1, A biodegradable adhesive, wherein the biodegradable adhesive further comprises a tackifier.

12. In paragraph 11, The above-mentioned adhesive is a biodegradable adhesive containing a natural polymer.

13. In paragraph 11, A biodegradable adhesive, wherein the tackifier is contained in an amount of 20 to 60 wt% based on the total weight of the biodegradable adhesive.

14. Description; and A biodegradable adhesive sheet comprising an adhesive layer positioned on the above-mentioned substrate and comprising a biodegradable adhesive according to any one of claims 1 to 13.

15. In paragraph 14, A biodegradable adhesive sheet, wherein the thickness of the adhesive layer is 50 to 500 ㎛.

16. In paragraph 14, The above description relates to a biodegradable adhesive sheet comprising a polymer film. 17.(S1) Step of oxidizing waste plastic by immersing it in an acid solution; (S2) A step of separating two or more types of aliphatic dicarboxylic acid compounds from a solution containing the oxidized waste plastic; (S3) a step of polymerizing by mixing the above aliphatic dicarboxylic acid compounds and epoxidized soybean oil; and (S4) A method for producing a biodegradable adhesive, comprising the step of curing the above polymer.

18. In paragraph 17, A method for manufacturing a biodegradable adhesive, wherein, in the step (S3), an adhesive agent is further added during mixing.

19. In Article 17, A method for producing a biodegradable adhesive, wherein two or more kinds of aliphatic dicarboxylic acid compounds obtained in the above step (S2) include aliphatic dicarboxylic acid compounds having 2 to 10 carbon atoms.

20. In paragraph 17, A method for producing a biodegradable adhesive, wherein the aliphatic dicarboxylic acid compounds obtained in the step (S2) contain 5 wt% or less of an aliphatic dicarboxylic acid compound having 3 or fewer carbon atoms and 50 to 100 wt% of an aliphatic dicarboxylic acid compound having 4 or more carbon atoms.

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